KR102750099B1 - Chemically stable alkyl aluminum solution, alkyl aluminum hydrolysate composition solution, composition for aluminum oxide film coating formation, article having aluminum oxide film, method for producing same, method for producing aluminum oxide thin-film, method for producing passivation film, passivation film, and solar cell element using same - Google Patents

Abstract

Disclosed are methods for producing an aluminum oxide thin film. (1) A solution containing an alkyl aluminum compound or a partial hydrolyzate thereof and a cyclic amide compound of the general formula (4). (2) A method for applying a composition containing a partial hydrolyzate of an organoaluminum compound represented by the general formula (6) to a surface of a substrate under an inert gas atmosphere, and heating the composition. (3) A method for forming an aluminum oxide film by spraying an organic solvent solution of the organoaluminum compound represented by the general formula (6) or a partial hydrolyzate thereof to form a coating film, and heating the same. (4) A method for obtaining an aluminum oxide thin film by applying a solution containing an alkyl aluminum compound and an organic solvent having electron donating properties and not containing active hydrogen atoms to a substrate, and heating the formed coating film. (5) A method for producing a silicon substrate having a passivation film using a passivation film forming agent composed of the above solution. A silicon substrate and a solar cell element having a passivation film.

Description

Chemically stable alkyl aluminum solution, alkyl aluminum hydrolyzed composition solution, composition for aluminum oxide film coating and forming, article having aluminum oxide film, method for producing same, method for producing aluminum oxide thin film, method for producing passivation film, passivation film, and solar cell element using same {CHEMICALLY STABLE ALKYL ALUMINUM SOLUTION, ALKYL ALUMINUM HYDROLYSATE COMPOSITION SOLUTION, COMPOSITION FOR ALUMINUM OXIDE FILM COATING FORMATION, ARTICLE HAVING ALUMINUM OXIDE FILM, METHOD FOR PRODUCING SAME, METHOD FOR PRODUCING ALUMINUM OXIDE THIN-FILM, METHOD FOR PRODUCING PASSIVATION FILM, PASSIVATION FILM, AND SOLAR CELL ELEMENT USING SAME}

The first aspect of the present invention (hereinafter sometimes referred to as “the present invention 1”) relates to an alkyl aluminum solution and an alkyl aluminum hydrolyzed composition having high chemical stability against air. The alkyl aluminum solution of the present invention 1 is a solution and composition usable as a stable alkylating agent and reactant that do not undergo chemical change even when handled in the air. By using the solution containing the alkyl aluminum partial hydrolyzate of the present invention 1, an aluminum oxide thin film can be formed even in the air.

The second aspect of the present invention (hereinafter sometimes referred to as “the present invention 2”) relates to a composition for forming an aluminum oxide film, a method for producing an article having an aluminum oxide film, and an article having an aluminum oxide film. The composition for forming an aluminum oxide film of the present invention 2 is a composition capable of forming an aluminum oxide film having excellent adhesion to a substrate.

The third aspect of the present invention (hereinafter sometimes referred to as “the present invention 3”) relates to a composition for forming an aluminum oxide film, a method for producing an article having an aluminum oxide film, and an article having an aluminum oxide film. The composition for forming an aluminum oxide film of the present invention 3 is a composition capable of forming an aluminum oxide film having excellent adhesion to a substrate.

The fourth aspect of the present invention (hereinafter, sometimes referred to as “the present invention 4”) relates to a simple method for producing an aluminum oxide thin film. Using the manufacturing method of the present invention 4, an aluminum oxide thin film can be formed simply.

The fifth aspect of the present invention (hereinafter sometimes referred to as “the present invention 5”) relates to a method for producing a passive film, a passive film, and a solar cell element using the same. By using the production method of the present invention 5, a passive film having a long carrier lifetime can be formed.

Cross-reference to related applications

This application claims the benefit of Japanese Patent Application No. 2014-168541, filed August 21, 2014, Japanese Patent Application No. 2014-168549, filed August 21, 2014, Japanese Patent Application No. 2014-238778, filed November 26, 2014, Japanese Patent Application No. 2015-031567, filed February 20, 2015, and Japanese Patent Application No. 2015-046592, filed March 10, 2015, the entire contents of which are specifically incorporated herein by reference.

<First aspect of the present invention>

Alkyl aluminum is widely used in various applications, such as a polymerization catalyst, a raw material for the synthesis of higher α-olefins and higher alcohols, a raw material for the synthesis of organometallic compounds, a raw material for the synthesis of ceramics, a raw material for compound semiconductors, and a reactant in the field of organic synthesis, due to its high reactivity (Non-patent Document 1-1).

Many alkyl aluminums, such as trimethylaluminum, triethylaluminum, and triisobutylaluminum, spontaneously combust when exposed to air, producing white alumina. Therefore, they are not easily handled in air.

Therefore, alkyl aluminum solutions diluted with organic solvents such as hexane, heptane, and toluene are often used. However, for example, when trimethyl aluminum is diluted with toluene, if the concentration exceeds 12 mass%, triethyl aluminum exceeds 12 mass%, and triisobutyl aluminum exceeds 26 mass%, each still exhibits residual spontaneous ignition. Therefore, in order to handle safely, it was necessary to use alkyl aluminum solutions diluted to a concentration lower than that (Non-patent Document 1-2). However, relatively low-concentration alkyl aluminum solutions diluted with organic solvents have a large volume, making transportation and other movements economically disadvantageous.

In addition, even if an alkyl aluminum solution is diluted to the point where it no longer has spontaneous combustion properties, it still retains its reactivity with air, and when it comes into contact with air, it reacts with the oxygen in the air to precipitate a white solid, which may block syringe needles, pipes, etc.

Meanwhile, a method of forming an aluminum oxide film using an alkyl aluminum solution or an alkyl aluminum hydrolysis composition solution obtained by reacting an alkyl aluminum solution with water is known (Patent Document 1-1).

Patent Document 1-1: WO2012/053433 A1

Non-patent literature 1-1: "Alkyl aluminum" Organic Synthetic Chemistry Vol. 43 No. 5 (1985) P475

Non-patent literature 1-2: "Pyrophoricity of Metal Alkyls", AkzoNobel Technical Bulletin August (2008) P1

However, the alkyl aluminum solution and the aluminum aluminum hydrolysis composition solution described in Patent Document 1-1 are reactive with water, and therefore, it is necessary to form an aluminum oxide film in an inert gas such as nitrogen or argon. Operation in an inert gas requires an inert gas, an inert gas supply facility, an inert gas holding facility such as a glove box, and there has been a problem that the cost of forming an aluminum oxide film increases.

The purpose of the present invention 1 is to provide an alkyl aluminum solution which has high stability in air, is substantially free of spontaneous combustion, can be handled in air, has a relatively small volume and can be made into a relatively high concentration which is economically advantageous for transportation, etc., and further, to provide a solution containing an alkyl aluminum partial hydrolyzate which is capable of forming an aluminum oxide thin film in the air. In addition, the present invention 1 provides a method for producing an aluminum oxide thin film in the air.

<Second aspect of the present invention>

Aluminum oxide has excellent properties such as strength, high heat resistance, high thermal conductivity, low thermal expansion coefficient, insulation, and density, so it is widely used in various industrial products.

Aluminum oxide has the shape of nanoparticles, powder, filler, plate shape, rod shape, etc., and is provided as an abrasive material, a refractory material, a heat-resistant material, an insulator, and a heat-radiating material. In addition, it is also used as a film having the above-mentioned characteristics, and is provided for the purposes of producing an alumina sheet for electronic materials, an aluminum oxide film, creating a catalyst carrier, imparting heat resistance, imparting barrier properties against air and moisture, imparting an antireflection effect, imparting an antistatic effect, imparting an antifogging effect, imparting wear resistance, etc., and as a binder for manufacturing ceramics. Specifically, there are applications such as protective films for machine parts or cutting tools, insulating films for semiconductors, magnetic materials, solar cells, etc., dielectric films, antireflection films, surface devices, magnetic heads, sensor elements such as infrared rays, barrier films against air and moisture in packaging materials for foods, drugs, medical devices, etc., coating films for substrates such as various powders, films, films or molded bodies made of glass or plastic, and heat-resistant materials, high-hardness films, and optical elements using these.

Various methods are known as methods for producing aluminum oxide. For example, the so-called Bayer method using bauxite as a starting material, and a method for producing aluminum alkoxide through hydrolysis are known. In addition, as methods for producing general aluminum oxide films, for example, the sputtering method, the MOCVD method, and the physical vapor deposition (PVD) method, such as deposition, which are film forming methods using a vacuum device, are well known.

In the formation of an aluminum oxide film, film formation by a coating method is known. This coating method has the advantages of high productivity and low manufacturing cost because the device is simple and the film formation speed is fast, and since there is no need to use a vacuum device and there is no restriction by a vacuum vessel, it is possible to create a large oxide film. As a coating method for forming an aluminum oxide film, an immersion coating method (Patent Documents 2-1 and 2-2), a spray pyrolysis method (Patent Document 2-3), a mist CVD method (Non-patent Document 2-1), a spin coating method (Patent Documents 2-4 to 2-6), etc. are known.

The spray pyrolysis method described in Patent Document 2-3 is a method of obtaining an aluminum oxide film by using a solution of an aluminum acetylacetonato complex as a raw material, spray-coating it, simultaneously drying the solvent, and then heating the substrate to a temperature of 500°C or higher.

The mist CVD method described in Non-Patent Document 2-1 is a method of obtaining an aluminum oxide film by using a solution of an aluminum acetylacetonato complex as a raw material, applying it in the form of mist, drying the solvent at the same time, and then heating the substrate to a temperature of 300°C or higher.

Various compositions have been proposed as compositions for forming an aluminum oxide film by a coating method. For example, Patent Documents 2-4 to 2-6 describe compositions for forming an aluminum oxide film using a complex of an amine compound and a hydrogenated aluminum compound. Patent Documents 2-5 to 2-7 describe using an organic solvent solution of alkyl aluminum as an organic aluminum compound.

These complexes of amine compounds and hydrogenated aluminum compounds or organic solvent solutions of alkyl aluminum are usually used for film coating by spin coating and immersion coating. After spin coating or immersion coating, the solvent is dried and then treated while contacting with moisture, which is an oxygen source, to form aluminum oxide.

Additionally, it is also known to use a partial hydrolyzate of an organic aluminum compound as a composition for forming an aluminum oxide film (Patent Documents 2-1, 2-2, 2-5, 2-6).

Partial hydrolyzates of organic aluminum compounds can also be used for film coating by spin coating and immersion coating methods. In a general formulation, after spin coating or immersion coating, the solvent is dried, and then the substrate temperature is heated to 450°C or higher to obtain an aluminum oxide film (Patent Documents 2-1, 2-2).

Patent Document 2-1: Japanese Patent Publication No. 58-95611

Patent Document 2-2: Japanese Patent Publication No. 58-91030

Patent Document 2-3: Japanese Publication No. 2007-270335

Patent Document 2-4: Japanese Publication No. 2007-287821

Patent Document 2-5: WO2012/053433A 1

Patent Document 2-6: WO2012/053436A 1

Patent Document 2-7: Japanese Patent Publication No. H4-139005

Non-patent Document 2-1: “Growth and electrical properties of AlOx grown by mist chemical vapor deposition”, Toshiyuki Kawaharamura, Takayuki Uchida, Masaru Sanada, Mamoru Furuta, AIP Advances, Vol. 3 (2013) 032135.

There are cases where an aluminum oxide film is applied by spin coating, dip coating, or the like using an organic aluminum compound, particularly, a complex of an amine compound and a hydrogenated aluminum compound, or an organic solvent solution of alkyl aluminum. For example, when using the complex of an amine compound and a hydrogenated aluminum compound described in Patent Document 2-4, in the case of forming an aluminum oxide film with a thin film thickness (about 150 nm), it is described that an aluminum oxide film is formed by treatment under an atmospheric pressure gas atmosphere using a mixture of oxygen and nitrogen. On the other hand, according to the examples described in Patent Documents 2-5 and 2-6, in order to obtain an aluminum oxide film with a thick film thickness (about 200 nm or more), it is necessary to dry the solvent after spin coating or dip coating, and then treat at 140°C for 3 hours while contacting it with moisture as an oxygen source under a pressure of 5 MPa or more. In this method, it is described that heat treatment under pressure for a long period of time is required, and that in treatment at 250°C in an atmospheric pressure gas atmosphere using a mixture of oxygen and nitrogen, metallic aluminum is formed.

In addition, in Patent Document 2-5, it is described that even in the case where an organic solvent solution of tridodecyl alkyl aluminum having an alkyl group of 12 carbon atoms is used as an organoaluminum compound, metallic aluminum is formed in a treatment under an atmospheric pressure gas atmosphere using a mixture of oxygen/nitrogen, etc.

In this way, when using a composition for forming an aluminum oxide film using a complex of an amine compound and a hydrogenated aluminum compound or an organic solvent solution of alkyl aluminum as an organoaluminum compound, there is a problem that an aluminum oxide film cannot be obtained under atmospheric pressure at 250°C or lower.

However, recently, a technology for forming oxide films on resin substrates such as films has been demanded. At that time, 1) lowering the film formation temperature, 2) adhesion to the substrate, and 3) the formation state of the oxide (e.g., transparency or homogeneity of the oxide film) are important factors. Therefore, the film formation of aluminum oxide films on resin substrates is usually performed by a vacuum-based deposition method or the like.

In particular, in the case of film formation on resins with low surface energy such as polyethylene and polypropylene, 2) adhesion to the substrate is a challenge. In order to improve the adhesion of the oxide film to the substrate, undercoat treatment, primer treatment, corona treatment, UV irradiation, chlorination, etc. are performed on the resin surface.

Until now, a composition having the performances 1) to 3) above has not been known for the coating of an aluminum oxide film using a composition for forming an aluminum oxide film.

Meanwhile, there has been little study on the application of an aluminum oxide film using a composition for forming an aluminum oxide film obtained by partially hydrolyzing an organoaluminum compound such as alkyl aluminum, and there are many problems with respect to the contents that have been studied. For example, Patent Document 2-1 discloses the application of an aluminum oxide film at 450°C using an organoaluminum compound having an isopropoxy group as a substituent bonded to Al. However, it is described that in this film formation, cracks appear in the thin film unless an additive such as butyl isocyanate having a large molecular weight is added. In addition, Patent Document 2-2 discloses the application of an aluminum oxide film using an organoaluminum compound having an ethoxy group or an isopropoxy group as a substituent bonded to Al. However, in the film formation at 500°C, there were problems such as the occurrence of cracks or the aluminum oxide film not adhering to the substrate.

In this way, in the case of coating an aluminum oxide film by directly applying a coating liquid to the surface of a substrate using a coating method such as a spin coating method or an immersion coating method, there are problems such as poor adhesion of the aluminum oxide film to the substrate or the formation of an aluminum oxide film (not forming a film shape) during film formation, which makes it difficult to form an aluminum oxide film.

Therefore, the purpose of the present invention 2 is to solve the problem of a coating film using a composition containing a partial hydrolyzate of an organoaluminum compound having an alkyl group having 1 to 4 carbon atoms such as triethylaluminum as a substituent, particularly, a coating film in which a coating liquid is directly applied to a substrate surface, and to provide a composition for forming an aluminum oxide film which, in film formation at a relatively low temperature, has excellent adhesion to a substrate including a resin substrate and a good oxide formation state (for example, transparency or homogeneity of the oxide film), and a method for forming an aluminum oxide film using the composition, and a method for manufacturing an article having an aluminum oxide film.

In addition, the present invention 2 provides an aluminum oxide film having a good oxide formation state (for example, transparency or homogeneity of the oxide film, etc.) manufactured using the manufacturing method of the present invention 2, and an article having the aluminum oxide film in a good adhesive state on a substrate.

<Third aspect of the present invention>

Aluminum oxide has excellent properties such as strength, high heat resistance, high thermal conductivity, low thermal expansion coefficient, insulation, and density, so it is widely used in various industrial products.

The background technology of aluminum oxide and its production method has been described in the background technology of the second aspect of the present invention.

In the formation of an aluminum oxide film, film formation by a coating method is known. This coating method has the advantages of high productivity and low manufacturing cost because the device is simple and the film formation speed is fast, and since there is no need to use a vacuum device, there is no restriction by a vacuum container, and thus creation of a large oxide film is possible. As a coating method for forming an aluminum oxide film, an immersion coating method (Patent Documents 3-1 and 3-2), a spray pyrolysis method (Patent Documents 3-3 to 3-7), a mist CVD method (Non-patent Document 3-1), a spin coating method (Patent Documents 3-8 to 3-10), etc. are known. Among these, various studies have been conducted on the formation of an aluminum oxide film using a film formation method by spray coating such as a spray pyrolysis method in particular (Patent Documents 3-3 to 3-7).

In addition, various compositions have been proposed as compositions for forming an aluminum oxide film, which are used in forming an aluminum oxide film by film deposition in a coating method. For example, in a method for forming an alumina film, which is aluminum oxide, a composition for forming an aluminum oxide film, using a complex of an amine compound and a hydrogenated aluminum compound, is described (Patent Documents 3-8 to 3-10). In addition, a composition for forming an organic solvent solution of alkyl aluminum is described as an organic aluminum compound (Patent Documents 3-9 to 3-11).

Patent Document 3-1: Japanese Patent Publication No. 58-95611

Patent Document 3-2: Japanese Patent Publication No. 58-91030

Patent Document 3-3: Japanese Publication No. 2006-161157

Patent Document 3-4: Japanese Publication No. 2007-270335

Patent Document 3-5: Japanese Publication No. 2007-238393

Patent Document 3-6: Japanese Publication No. 2009-120873

Patent Document 3-7: Japanese Publication No. 2010-209363

Patent Document 3-8: Japanese Publication No. 2007-287821

Patent Document 3-9: WO2012/053433A 1

Patent Document 3-10: WO2012/053436A 1

Patent Document 3-11: Japanese Patent Publication No. 4-139005

Non-patent Document 3-1: “Growth and electrical properties of AlOx grown by mist chemical vapor deposition” Toshiyuki Kawaharamura, Takayuki Uchida, Masaru Sanada, Mamoru Furuta AIP Advances, Vol.3(2013)032135.

Recently, oxide film formation on resin substrates such as films has been demanded, and 1) lowering the film formation temperature, 2) adhesion to the substrate, and 3) the formation state of the oxide are important factors. Therefore, aluminum oxide film formation on resin substrates is also usually performed by a vacuum-based deposition method, etc.

In the investigations using the spray coating method known so far, inorganic salts such as aluminum chloride, or organic aluminum complexes such as aluminum acetate, aluminum isopropoxide, or aluminum tris acetylacetonate have been used as the aluminum source. However, the film formation temperature when these are used is usually high, such as 500°C or higher, and furthermore, organic aluminum complexes such as aluminum tris acetylacetonate have low solubility in organic solvents, and it is difficult to increase the concentration of the aluminum source, so that it is difficult to increase the productivity of the aluminum oxide film in the spray film formation using these. Thus, in the aluminum oxide film formation compositions composed of aluminum compounds that have been investigated so far, it has been difficult to form an aluminum oxide film at a temperature of 250°C or lower, which is capable of forming a film on a resin substrate.

Meanwhile, as a composition for forming an aluminum oxide film that can be used as an aluminum source in a coating film, there is an organic solvent solution of alkyl aluminum as an organic aluminum compound, but alkyl aluminum is flammable in the air, so it is a compound that requires extreme care during storage and use. Therefore, it is extremely difficult to spray-apply alkyl aluminum and perform spray pyrolysis.

In addition, it is known that the lower the carbon number of alkyl aluminum, the higher the reactivity with oxygen or water. Therefore, in patent documents 3-9 and 3-10, in examples regarding spin coating film formation using alkyl aluminum, alkyl aluminum having 4 or more carbon atoms, such as diisobutyl aluminum hydride (4 carbon atoms in the alkyl group) or trioctyl aluminum (8 carbon atoms in the alkyl group), is used. In addition, spin coating film formation is used as these film formation methods, but film formation by spray pyrolysis has not been performed, and is still unclear.

In addition, in the case of hydrides such as diisobutyl aluminum hydride, when an ether solvent such as anisole is used as a solvent, there is a risk of reaction between the hydride and the ether solvent, and there is a risk of decomposition due to a reaction of the chemical liquid when the temperature becomes high.

In this way, in the case of forming an aluminum oxide film by spraying a composition in which alkyl aluminum is dissolved in an organic solvent onto a substrate and thermally decomposing it, it cannot be said that sufficient research has been done, and there are still many challenges.

In addition, as for the partial hydrolyzate of alkyl aluminum, in the case of forming an aluminum oxide film by spraying it onto a substrate and thermally decomposing it, as in the case of a composition in which alkyl aluminum is dissolved in an organic solvent, it cannot be said that it has been studied, and there are still many tasks to be done.

The purpose of the present invention 3 is to provide a method for producing an aluminum oxide film, which comprises spraying a composition in which alkyl aluminum or a partial hydrolyzate of alkyl aluminum is dissolved in an organic solvent, and thermally decomposing the composition to form an aluminum oxide film, thereby obtaining an aluminum oxide film with excellent adhesion, and a film-forming composition that can be used in the method.

In addition, the purpose of the present invention 3 is to provide an aluminum oxide film manufactured using the above-mentioned manufacturing method, and further to provide an aluminum oxide functional film including the aluminum oxide film and an article which is a substrate having the film or functional film.

<Fourth aspect of the present invention>

Aluminum oxide has excellent properties such as high strength, high heat resistance, high thermal conductivity, low thermal expansion rate, and insulation, so it is widely used in various applications.

As an aluminum oxide thin film, it is provided for the purposes of producing an aluminum oxide sheet for electronic materials, an aluminum oxide film, producing a catalyst carrier, imparting heat resistance, imparting barrier properties to air and moisture, imparting an antireflection effect, imparting an antistatic effect, imparting an antifogging effect, imparting wear resistance, etc., and as a binder for ceramic manufacturing, and such an aluminum oxide thin film is required to have high purity (Non-patent Document 4-1).

Specifically, applications include protective films for cutting tools, insulating films for semiconductors, magnetic materials, solar cells, etc., surface devices, magnetic heads, infrared sensors, packaging materials for foods, drugs, medical devices, etc., and optical elements.

The method for manufacturing an aluminum oxide thin film includes sputtering, chemical vapor deposition (CVD), and atomic layer deposition (ALD).

However, since sputtering, CVD, ALD, etc. require the use of large sealed containers, there were problems such as high manufacturing costs of aluminum oxide thin films and low material usage efficiency.

Coating methods such as spin coating, immersion coating, screen printing, die coating, and spray coating have the advantages of not requiring a sealed container, requiring simple equipment, producing a film at a fast film formation speed, and producing an aluminum oxide film at a low manufacturing cost compared to the above methods.

Various studies have been conducted on the formation of aluminum oxide thin films using a film-forming method by spray application, such as a spray pyrolysis method, as a coating method (Patent Documents 4-1 to 4-2).

Patent Document 4-1: Japanese Publication No. 2007-238393

Patent Document 4-2: Japanese Publication No. 2010-209363

Non-patent literature 4-1: Yasaka JETI., 10 (2005) P134 to 140

However, in the methods described in the above patent documents 4-1 to 4-2, when manufacturing a passive film by heat treatment (firing) together, it is necessary to degrease (remove) residual organic components such as binder resin and ligand by firing, so there was a problem that a long time was required for firing, or heat treatment at a high temperature of about 400 to 1000°C was required.

In addition, there was a challenge that it was difficult to obtain a transparent zinc oxide thin film (with a transmittance of 80% or more at 550 nm of visible light) by heat treatment at low temperatures.

In particular, there was the challenge that it could not be applied to non-heat-resistant materials such as plastics because it required firing at 300℃ or higher.

Trialkyl aluminum compounds such as triethyl aluminum are flammable in the air, and therefore must be stored and used with extreme care. Therefore, it is practically difficult to use trialkyl aluminum compounds in spray application methods, which are usually performed in an atmosphere containing water, without diluting them. Trialkyl compounds can reduce the risk of flammability and the like when diluted in an organic solvent, but there have been no cases of examining spray application of trialkyl compounds diluted in an organic solvent.

In addition, the application operation in an inert gas requires inert gas, inert gas supply equipment, and inert gas holding equipment such as a glove box, which increases the manufacturing cost of aluminum oxide, and there was a challenge that further simplification was required.

The purpose of the present invention 4 is to provide a simple method for producing an aluminum oxide thin film. Using the production method of the present invention 4, a transparent aluminum oxide thin film with little residual organic matter can be easily formed.

<Fifth aspect of the present invention>

In order to improve the efficiency of crystalline silicon solar cells, it is important to passivate the back surface of the solar cell and suppress back-side recombination of carriers. For this reason, a passivation film may be formed on the back surface of the silicon substrate.

As this passive film, a technology utilizing silicon oxide, silicon nitride, aluminum oxide, zinc oxide, etc. has been proposed (Patent Document 5-1). In particular, with regard to p-type silicon substrates, silicon nitride, etc., which have a positive fixed charge, are not suitable because leakage current is likely to occur, and aluminum oxide, which has a negative fixed charge, is suitable (Patent Document 5-2).

The method for manufacturing the aluminum oxide thin film as a passive film is formed by methods such as sputtering, chemical vapor deposition (CVD), and atomic layer deposition (ALD).

However, since sputtering, CVD, and ALD methods require the use of large sealed containers, there are problems such as increased manufacturing costs for aluminum oxide thin films and decreased material usage efficiency.

Coating methods such as spin coating, immersion coating, screen printing, die coating, and spray coating have the advantages of not requiring a sealed container and having simple equipment, allowing for a fast film formation speed and low manufacturing cost in comparison with the above methods, allowing for the production of aluminum oxide thin films.

As a coating method, a manufacturing method using a spin coating method (Non-patent Document 5-1) and a manufacturing method using a screen printing method (Patent Document 5-3) are proposed.

Patent Document 5-1: Japanese Publication No. 2009-164544

Patent Document 5-2: Japanese Patent No. 4767110

Patent Document 5-3: Japanese Publication No. 2014-167961

Non-patent literature 5-1: Thin Solid Films, 517(2009), 6327-6330

However, in the methods described in the above-mentioned non-patent documents 5-1 and patent documents 5-3, when manufacturing a passive film by heat treatment (firing) together, it is necessary to degrease (remove) residual organic components such as binder resin and ligand by firing, so there was a problem that a long time was required for firing, or heat treatment at a high temperature of 650 to 1000°C was required.

In addition, the carrier lifetime of the passive film manufactured by the method described in the above-mentioned non-patent literature 5-1 and patent literature 5-3 is shorter than that of the passive film manufactured by the ALD method, which is 100 to 500 μs when the substrate wafer thickness is about 700 μm, and therefore, further improvement in the carrier lifetime has been demanded.

The purpose of the present invention 5 is to provide a simple method for manufacturing a passive film, a passive film, and a solar cell element using the same. Using the manufacturing method of the present invention 5, a passive film having a long carrier lifetime can be formed.

The above patent documents 1-1 to 5-3 and non-patent documents 1-1 to 5-1 are specifically incorporated herein by reference in their entirety.

The present invention 1 is as follows.

[1-1] A solution containing an alkyl aluminum compound comprising dialkyl aluminum, trialkyl aluminum or a mixture thereof (wherein the alkyl group has 1 to 6 carbon atoms and may be the same or different) and a solvent,

The above solvent is an organic compound having a boiling point of 160°C or higher, an amide structure represented by the following general formula (4), and a cyclic structure (hereinafter referred to as a “cyclic amide compound”).

A solution containing the cyclic amide compound in an amount exceeding 2.6 in molar ratio with respect to the alkyl aluminum compound:

.

[1-2] The solution described in [1-1], wherein the above-mentioned cyclic amide compound is N-methyl-2-pyrrolidone, or 1,3-dimethyl-imidazolidinone, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, or a mixture thereof.

[1-3] A solution according to any one of [1-1] or [1-2], wherein the content of the alkyl aluminum compound is 15 mass% or more.

[1-4] A solution according to any one of [1-1] to [1-3], wherein the dialkyl aluminum and/or trialkyl aluminum is an alkyl aluminum compound represented by the following general formula (1) or (2):

(In the formula, R ¹ represents a methyl group or an ethyl group, and R ² represents a halogen, a methyl group, or an ethyl group.)

(In the formula, R ³ represents an isobutyl group and R ⁴ represents a halogen or an isobutyl group.)

[1-5] A solution described in [1-4], wherein the alkyl aluminum compound represented by the general formula (1) is triethyl aluminum or trimethyl aluminum.

[1-6] A solution described in [1-4], wherein the alkyl aluminum compound represented by the general formula (2) is triisobutyl aluminum.

[1-7] A solution described in [1-6] containing 30 mass% or more of an alkyl aluminum compound represented by the general formula (2).

[1-8] A solution according to any one of [1-1] to [1-7], further comprising a solvent other than the above-mentioned cyclic amide compound.

[1-9] A solution containing a partial hydrolyzate of an alkyl aluminum compound composed of dialkyl aluminum, trialkyl aluminum or a mixture thereof (provided that the alkyl group has 1 to 6 carbon atoms and may be the same or different) and a solvent,

The above solvent is an organic compound having a boiling point of 160°C or higher, an amide structure represented by the following general formula (4), and a cyclic structure (hereinafter referred to as a “cyclic amide compound”).

The above partial hydrolyzate is a solution in which the aluminum in the alkyl aluminum compound is hydrolyzed with water in a molar ratio ranging from 0.5 to 1.3:

.

[1-10] A solution as described in [1-9], containing at least 1 of the above cyclic amide compounds in a molar ratio with respect to aluminum among the above alkyl aluminum compounds.

[1-11] The solution described in [1-9] or [1-10], wherein the above-mentioned cyclic amide compound is N-methyl-2-pyrrolidone, or 1,3-dimethyl-imidazolidinone, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, or a mixture thereof.

[1-12] A solution according to any one of [1-9] to [1-11], wherein the dialkyl aluminum and/or trialkyl aluminum is an alkyl aluminum compound represented by the following general formula (1) or (2):

(In the formula, R ¹ represents a methyl group or an ethyl group, and R ² represents hydrogen, halogen, a methyl group or an ethyl group.)

(In the formula, R ³ represents an isobutyl group, and R ⁴ represents hydrogen, halogen, or an isobutyl group.)

[1-13] A solution according to any one of [1-9] to [1-11], wherein the trialkyl aluminum is an alkyl aluminum compound represented by the following general formula (3):

(In the formula, R ⁵ represents a methyl group, an ethyl group, or an isobutyl group.)

[1-14] A solution according to any one of [1-9] to [1-13], further comprising a solvent other than the above-mentioned cyclic amide compound.

[1-15] A method for producing an aluminum oxide thin film, comprising applying a solution containing an alkyl aluminum partial hydrolyzate as described in any one of [1-9] to [1-14] to a substrate to obtain an aluminum oxide thin film.

The present invention 2 is as follows.

[2-1] (A) A process for obtaining a composition containing a partial hydrolyzate of an organoaluminum compound represented by the general formula (6) below by partially hydrolyzing the organoaluminum compound in an organic solvent, wherein the partial hydrolysis is performed using water having a molar ratio of 0.4 to 1.3 with respect to the organoaluminum compound.

(B) a process of forming a coating film by applying the composition containing the above-mentioned partial hydrolyzate to at least a portion of the surface of a substrate under an inert gas atmosphere;

(C) A method for manufacturing an article having an aluminum oxide film, comprising a step of forming an aluminum oxide film by heating a substrate having the above coating film formed at a temperature of 400°C or lower in an inert gas atmosphere:

(In the formula, R ¹ represents hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, and R ² and R ³ independently represent hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, a straight-chain or branched alkoxyl group having 1 to 7 carbon atoms, an acyloxy group, or an acetylacetonate group.)

[2-2] The manufacturing method described in [2-1], wherein the inert gas atmosphere used in the above processes (B) and (C) substantially does not contain moisture.

[2-3] A manufacturing method described in [2-1] or [2-2], wherein application of the partially hydrolyzed product-containing composition in the above process (B) is performed at a temperature in the range of 20 to 350°C.

[2-4] A manufacturing method according to any one of [2-1] to [2-3], wherein the heating temperature in the above process (C) is in the range of 40 to 400°C.

[2-5] A manufacturing method according to any one of [2-1] to [2-4], wherein the coating base material obtained in the above process (B) is heated at a temperature of 20 to 200°C under an inert gas atmosphere, at least a portion of the organic solvent in the coating film is removed, and then provided to process (C) to form an aluminum oxide film.

[2-6] A manufacturing method according to any one of [2-1] to [2-5], wherein in the above process (A), after mixing the organic aluminum compound and water, the mixture is heated to a temperature of 30 to 80°C to obtain a composition containing a partial hydrolyzate.

[2-7] A manufacturing method according to any one of [2-1] to [2-6], wherein the composition containing the partial hydrolyzate prepared in the above process (A) is filtered to remove insoluble matter and then used in the process (B).

[2-8] A manufacturing method according to any one of [2-1] to [2-7], wherein the composition is applied to a substrate by a spray coating method, an immersion coating method, a spin coating method, a slit coating method, a slot coating method, a bar coating method, a roll coating method, a curtain coating method, an electrostatic coating method, an inkjet method, or a screen printing method.

[2-9] A manufacturing method according to any one of [2-1] to [2-8], wherein the organic solvent used in preparing the above partial hydrolyzate is an organic solvent containing a hydrocarbon compound and/or an electron-donating solvent.

[2-10] A manufacturing method according to any one of [2-1] to [2-9], wherein the concentration of the partial hydrolyzate in the composition containing the partial hydrolyzate prepared in the above process (A) is in the range of 0.1 to 30 mass%.

[2-11] The organic aluminum compound represented by the general formula (6) used in the above process (A) is a manufacturing method according to any one of [2-1] to [2-10], wherein R ¹ in the formula is a methyl group or an ethyl group.

[2-12] A manufacturing method according to any one of [2-1] to [2-11], wherein the organoaluminum compound represented by the general formula (6) used in the above process (A) is triethylaluminum or a mixture of organoaluminum compounds containing triethylaluminum.

[2-13] A manufacturing method according to any one of [2-1] to [2-12], wherein the substrate used in the above process (B) is a glass substrate or a resin substrate.

[2-14] A composition containing a partial hydrolyzate of an organoaluminum compound obtained by partially hydrolyzing the organoaluminum compound represented by the following general formula (6) in an organic solvent,

(A) The partial hydrolysis is performed using water having a molar ratio of 0.4 to 1.3 to the organoaluminum compound, and

(b) The composition is a material for use in the formation of an aluminum oxide film, the film formation being performed under an inert gas atmosphere:

(In the formula, R ¹ represents hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, and R ² and R ³ independently represent hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, a straight-chain or branched alkoxyl group having 1 to 7 carbon atoms, an acyloxy group, or an acetylacetonate group.)

[2-15] The film-coating process performed under the above inert gas atmosphere comprises: (b1) a process of forming a film by applying the partially hydrolyzed product-containing composition to at least a portion of the surface of a substrate under an inert gas atmosphere, and

(b2) A composition as described in [2-14], including a process of forming an aluminum oxide film by heating the substrate on which the coating film has been formed at a temperature of 400° C. or lower in an inert gas atmosphere.

[2-16] A composition described in [2-14] or [2-15], which is substantially free of insoluble matter and is filtered using a filter having a pore diameter of 3 ㎛ or less.

[2-17] A composition according to any one of [2-14] to [2-16] for forming a transparent aluminum oxide film in close contact with a substrate.

[2-18] An article having an aluminum oxide film, manufactured under an inert gas atmosphere using a method described in any one of [2-1] to [2-13], or a composition described in any one of [2-14] to [2-17].

[2-19] An article having an aluminum oxide film as described in [2-18], wherein the article is a composite in which an aluminum oxide film is attached to a substrate or a composite film having a layer other than an aluminum oxide film and an aluminum oxide film is attached to a substrate.

The present invention 3 is as follows.

[3-1] (A) A process for forming a coating film by spraying an organic solvent solution of an organoaluminum compound represented by the following general formula (6) or a partial hydrolyzate thereof onto at least a portion of the surface of a substrate (provided that the partial hydrolyzate is a substance obtained by partially hydrolyzing the organoaluminum compound in an organic solvent using water in a molar ratio of 0.7 or less to the organoaluminum compound, and the spraying is performed under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture);

(B) A method for manufacturing an article having an aluminum oxide film, comprising the step of heating a substrate having the coating film formed thereon at a temperature of 400° C. or lower under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture, and forming an aluminum oxide film from the coating film:

(In the formula, R ¹ represents hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, and R ² and R ³ independently represent hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, a straight-chain or branched alkoxyl group having 1 to 7 carbon atoms, an acyloxy group, or an acetylacetonate group.)

[3-2] In the above process (A), an organic solvent solution of an organic aluminum compound is used,

A manufacturing method described in [3-1], wherein in general formula (6), R ¹ represents a straight-chain or branched alkyl group having 1 to 3 carbon atoms, and R ² and R ³ independently represent a straight-chain or branched alkyl group having 1 to 3 carbon atoms, a straight-chain or branched alkoxyl group having 1 to 7 carbon atoms, an acyloxy group, or an acetylacetonate group.

[3-3] The organic solvent contains an organic solvent having electron donating properties, and

A manufacturing method described in [3-2], wherein the concentration of the organic aluminum compound in the solution is 0.1 to 35 wt%.

[3-4] A manufacturing method described in [3-3], characterized in that the mole number of molecules constituting the organic solvent having the electron-donating property is equal to or greater than the mole number of the organic aluminum compound.

[3-5] A manufacturing method according to any one of [3-2] to [3-4], wherein the temperature of the surface of the substrate is 20 to 300°C in the spray application of the above process (A).

[3-6] In the above process (A), an organic solvent solution of a partial hydrolyzate of an organoaluminum compound is used,

The manufacturing method described in [3-1], wherein the organic solvent used in the above process (A) is an organic solvent containing a hydrocarbon compound and/or an organic solvent having electron-donating properties.

[3-7] A manufacturing method described in [3-6], wherein the concentration of partial hydrolyzate in the organic solvent solution is in the range of 0.1 to 35 mass%.

[3-8] A manufacturing method described in [3-6] or [3-7], wherein the above process (A) is performed under heating at a temperature of 400°C or lower, and heating in the process (B) is performed simultaneously with or continuously from the above process (A).

[3-9] The above spray application is a manufacturing method according to any one of [3-1] to [3-8], wherein the spray application is performed by a spray application method, a spray pyrolysis method, an electrostatic application method, or an inkjet method.

[3-10] A manufacturing method according to any one of [3-1] to [3-9], wherein R ¹ in the general formula (6) is a methyl group or an ethyl group.

[3-11] A film-forming composition comprising an organic solvent solution of an organoaluminum compound represented by the following general formula (6),

The composition is a material for use in the formation of an aluminum oxide film, wherein the film coating and formation is performed under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture.

(In the formula, R ¹ represents hydrogen, a straight-chain or branched alkyl group having 1 to 3 carbon atoms, and R ² and R ³ independently represent hydrogen, a straight-chain or branched alkyl group having 1 to 3 carbon atoms, a straight-chain or branched alkoxyl group having 1 to 7 carbon atoms, an acyloxy group, or an acetylacetonate group.)

[3-12] A film-forming composition containing a partial hydrolyzate of an organoaluminum compound obtained by partially hydrolyzing the organoaluminum compound represented by the following general formula (6) in an organic solvent,

(A) The partial hydrolysis is performed using water having a molar ratio of 0.7 or less to the organoaluminum compound, and

(b) The composition is a material for use in the formation of an aluminum oxide film, wherein the film-forming process is performed under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture.

(In the formula, R ¹ represents hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, and R ² and R ³ independently represent hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, a straight-chain or branched alkoxyl group having 1 to 7 carbon atoms, an acyloxy group, or an acetylacetonate group.)

[3-13] The film formation performed under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture is

(c1) a process of forming a coating film by spraying the composition onto at least a portion of the surface of a substrate under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture, and

(c2) A composition as described in [3-11] or [3-12], comprising a process of forming an aluminum oxide film by heating the substrate on which the coating film has been formed at a temperature of 400° C. or lower under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture.

[3-14] A composition according to any one of [3-11] to [3-13] for forming a transparent aluminum oxide film in close contact with a substrate.

[3-15] An article having an aluminum oxide film, manufactured under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture using the method described in any one of [3-1] to [3-10], or the composition described in any one of [3-11] to [3-14].

[3-16] An article having an aluminum oxide film as described in [3-15], wherein the article is a composite in which an aluminum oxide film is attached to a substrate or a composite film having a layer other than an aluminum oxide film and an aluminum oxide film is attached to a substrate.

The present invention 4 is as follows.

[4-1] A method for producing an aluminum oxide thin film, characterized by forming a coating film by applying a solution containing an alkyl aluminum compound, which contains an alkyl aluminum compound composed of dialkyl aluminum, trialkyl aluminum or a mixture thereof (provided that the alkyl groups of the dialkyl aluminum and trialkyl aluminum have 1 to 6 carbon atoms and may be the same or different), and an organic solvent having electron donating properties and not containing active hydrogen atoms, in the form of droplets having an average particle diameter of 1 to 100 µm in the air to a substrate, and then heating the formed coating film to form aluminum oxide after drying the organic solvent or in parallel with drying the organic solvent.

[4-2] The manufacturing method described in [4-1], characterized in that the above droplets have an average particle diameter in the range of 3 to 30 ㎛.

[4-3] The manufacturing method described in [4-1] or [4-2], characterized in that the application to the substrate is performed on the substrate heated to a temperature of 300°C or lower.

[4-4] A manufacturing method according to any one of [4-1] to [4-3], wherein the atmospheric temperature in the air is 50°C or lower and the relative humidity converted to 25°C is 20 to 90%.

[4-5] A manufacturing method according to any one of [4-1] to [4-4], wherein the above application is performed by spray application, mist CVD, or inkjet method.

[4-6] A manufacturing method according to any one of [4-1] to [4-5], wherein the dialkyl aluminum and/or trialkyl aluminum is an alkyl aluminum compound represented by the following general formula (8) or (9):

(In the formula, R ¹ represents a methyl group or an ethyl group.)

(In the formula, R ² represents an isobutyl group, and R ³ represents hydrogen or an isobutyl group.)

[4-7] A manufacturing method described in [4-6], wherein the alkyl aluminum compound represented by the general formula (8) is triethyl aluminum.

[4-8] A manufacturing method described in [4-7], wherein the content of the alkyl aluminum compound in the solution containing the triethyl aluminum is 1 mass% or more and 10 mass% or less.

[4-9] A manufacturing method according to any one of [4-1] to [4-8], wherein the vertical transmittance of the aluminum oxide thin film at visible light 550 nm is 80% or more.

The present invention 5 is as follows.

[5-1] A passive film forming agent comprising an alkyl aluminum compound comprising dialkyl aluminum, trialkyl aluminum or a mixture thereof (provided that the alkyl groups of the dialkyl aluminum and trialkyl aluminum have 1 to 6 carbon atoms and may be the same or different), and a solution containing an alkyl aluminum compound containing an organic solvent having electron donating properties and not containing active hydrogen atoms.

[5-2] The passive film forming agent described in [5-1], wherein the dialkyl aluminum and/or trialkyl aluminum is an alkyl aluminum compound represented by the following general formula (8) or (9):

(In the formula, R ¹ represents a methyl group or an ethyl group.)

(In the formula, R ² represents an isobutyl group, and R ³ represents hydrogen or an isobutyl group.)

[5-3] A passive film forming agent as described in [5-2], wherein the alkyl aluminum compound represented by the general formula (8) is triethyl aluminum.

[5-4] A passive film forming agent as described in [5-3], wherein the content of the alkyl aluminum compound of triethyl aluminum in the solution is 1 mass% or more and 10 mass% or less.

[5-5] A method for manufacturing a silicon substrate having a passive film, characterized by forming a film by applying a passive film forming agent described in [5-1] to [5-4] in the form of droplets having an average particle diameter of 1 to 100 ㎛ to at least a portion of the back surface of a silicon substrate, and then heating the formed film to form aluminum oxide after drying an organic solvent, or in parallel with drying the organic solvent.

[5-6] The manufacturing method described in [5-5], characterized in that the droplets have an average particle diameter in the range of 3 to 30 ㎛.

[5-7] A manufacturing method described in [5-5] or [5-6], wherein the above application is performed by a spray application method.

[5-8] A manufacturing method described in [5-7], wherein the substrate temperature at the time of spray application is in the range of 300 to 550°C, and/or the temperature at the time of heating after spray application is in the range of 300 to 550°C.

[5-9] A silicon substrate having a passivation film, characterized in that it is manufactured by the method described in any one of [5-5] to [5-8].

[5-10] A solar cell device using a silicon substrate having a passive film as described in [5-9].

[Effect of the invention]

According to the present invention 1, a high-concentration alkyl aluminum solution can be provided that is non-flammable and stable in air, thus being easy to handle, and has a small volume, thereby being economically advantageous for transportation, etc. In addition, according to the present invention 1, a solution containing an alkyl aluminum partial hydrolyzate that is stable in air, thus being easy to handle, and capable of forming an aluminum oxide film in the air can be provided.

According to the present invention 2, in film formation at a relatively low temperature, an aluminum oxide film coating-forming composition can be provided which can provide an aluminum oxide film by a coating film having excellent adhesion to a substrate including a resin substrate and a good oxide formation state (for example, transparency or homogeneity of the oxide film). By using this composition, by directly applying a coating liquid which is the composition of the present invention 2 to a surface of a substrate, and even in a film formation by heating at a relatively low temperature, an aluminum oxide film having excellent adhesion to a substrate including a resin substrate and a good oxide formation state (for example, transparency or homogeneity of the oxide film) can be directly formed on the surface of the substrate. In addition, according to the present invention 2, a method for forming an aluminum oxide film using the composition of the present invention 2 and a method for manufacturing an article comprising a substrate having an aluminum oxide film on its surface can be provided.

By using the manufacturing method of the present invention 3 and the composition for manufacturing an aluminum oxide film, an aluminum oxide film having excellent adhesion to a substrate and a good oxide formation state can be formed even at a low film formation temperature by simply performing coating and heating.

More specifically, according to the present invention 3, by using a coating solution in which an organoaluminum compound having an alkyl group having 1 to 3 carbon atoms, such as triethylaluminum (2 carbon atoms), or a partial hydrolyzate thereof, is dissolved in an organic solvent containing an electron-donating organic solvent, etc., handling in the film-forming operation of a reactive compound such as alkylaluminum is facilitated, and the reaction in the spray film-forming becomes easy to control, so that even at a low temperature of 400°C or lower, an aluminum oxide film having excellent adhesion to a substrate and a good oxide formation state can be formed simply by performing coating and heating.

In addition, since the aluminum oxide film manufactured by the method of the present invention 3 has excellent adhesion to a substrate and a good oxide formation state, it is provided for uses such as manufacturing an alumina sheet for electronic materials, an aluminum oxide film, manufacturing a catalyst carrier, imparting heat resistance, imparting barrier properties against air and moisture, imparting an antireflection effect, imparting an antistatic effect, imparting an antifogging effect, imparting wear resistance, etc., and as a binder for ceramic manufacturing, and specifically, it can be applied as an aluminum oxide functional film such as an aluminum oxide film used for uses such as a protective film for machine parts or cutting tools, an insulating film for semiconductors, magnetic bodies, solar cells, etc., a dielectric film, an antireflection film, a surface device, a magnetic head, an infrared ray sensor element, a barrier film against air, moisture, etc. in packaging materials for foods, drugs, medical devices, etc., a coating film for substrates such as various powders, films, films or molded bodies made of glass or plastic, and heat-resistant materials, high-hardness films, optical elements, and binders for ceramic manufacturing using these.

In addition, the substrates having these aluminum oxide films or aluminum oxide functional films can be used as heat-resistant materials such as heat-resistant films, insulating materials, materials such as barrier films against moisture or oxygen, anti-reflection materials such as anti-reflection films and glass, and high-hardness films or materials.

According to the present invention 4, an aluminum oxide thin film can be easily manufactured at a low temperature, and a transparent aluminum oxide thin film with little residual organic matter can be easily formed.

According to the present invention 5, an aluminum oxide thin film with less residual organic matter can be easily manufactured at a low temperature, and a passive film with a long carrier life time can be formed.

Figure 1a is a ¹ H-NMR spectrum of a triethylaluminum hydrolyzed composition NMP solution.
Figure 1b is an IR spectrum of a dried NMP solution of triethylaluminum hydrolyzed composition by transmission method.
Figure 1c is an external photograph of an aluminum oxide thin film.
Figure 1d is an IR spectrum of an aluminum oxide thin film obtained by the ATR method.
Figure 1e is an IR spectrum of a glass substrate (EagleXG, Corning Corporation) by the ATR method.
Figure 2a is a drawing showing a spray film forming device.
Figure 2b is a ^1H -NMR spectrum of composition A obtained in Example 2-1 after vacuum drying.
Figure 2c is an ATR-IR spectrum of an aluminum oxide film obtained on a glass substrate by film formation by heating at 130°C in Example 2-1.
Figure 2d is an ATR-IR spectrum of a glass substrate used in the film formation by heating at 130°C in Example 2-1.
Figure 2e is ^{a 1H} -NMR spectrum of composition B obtained in Example 2-3 after vacuum drying.
Figure 2f is ^{a 1H} -NMR spectrum of the composition C obtained in Example 2-5 after vacuum drying.
Figure 2g is a ^1H -NMR spectrum of the composition K obtained in Example 2-15 after vacuum drying.
Figure 2h is the ²⁷ Al-NMR spectrum of the composition K obtained in Example 2-15 after vacuum drying.
Figure 2i is a ^1H -NMR spectrum of the composition N obtained in Example 2-20 after vacuum drying.
Figure 2j is a ^1H -NMR spectrum of the composition O obtained in Example 2-21 after vacuum drying.
Figure 2k is the ²⁷ Al-NMR spectrum of the composition O obtained in Example 2-21 after vacuum drying.
Figure 2l is an ATR-IR spectrum of an aluminum oxide film obtained on a porous polypropylene (PP) film by heating at 50°C in a nitrogen atmosphere in Example 2-23.
Figure 2m is an ATR-IR spectrum of an aluminum oxide film obtained on a porous polypropylene (PP) film by heating at 50°C in an air atmosphere in Example 2-23.
Figure 2n is an ATR-IR spectrum of a porous polypropylene (PP) film used in the film formation by heating at 50°C in an air or nitrogen atmosphere in Example 2-23.
Figure 2o is a scanning electron microscope photograph (thin film cross-section) of an aluminum oxide film obtained on a glass substrate by heating at 50°C in a nitrogen atmosphere in Example 2-24.
Figure 2p is a scanning electron microscope photograph (thin film surface) of an aluminum oxide film obtained on a glass substrate by film formation by heating at 50°C in a nitrogen atmosphere in Example 2-24.
Figure 2q is an ATR-IR spectrum (before peeling test) of an aluminum oxide film obtained on a polypropylene (PP) film by heating at 100° C. in a nitrogen atmosphere using composition H in Example 2-38.
Figure 2r is an ATR-IR spectrum after a peeling test of an aluminum oxide film obtained on a polypropylene (PP) film by heating at 100° C. in a nitrogen atmosphere using composition H in Example 2-38.
Figure 2s is an ATR-IR spectrum (before peeling test) of an aluminum oxide film obtained on a polypropylene (PP) film by heating at 100°C in a nitrogen atmosphere using composition 3 in Comparative Example 2-6.
Figure 2t is an ATR-IR spectrum of an aluminum oxide film obtained on a polypropylene (PP) film by heating at 100°C in a nitrogen atmosphere using composition 3 in Comparative Example 2-6 after a peeling test.
Figure 2u is a scanning electron microscope photograph (thin film surface) of an aluminum oxide film formed on paper obtained in Example 2-40.
Figure 3a is a drawing showing a spray film forming device.
Figure 3b is a scanning electron microscope image (thin film surface) of the aluminum oxide film obtained in Example 3-1-1.
Figure 3c is a scanning electron microscope photograph (thin film cross-section) of the aluminum oxide film obtained in Example 3-1-1.
Figure 3d is a scanning electron microscope image (thin film surface) of the aluminum oxide film obtained in Example 3-1-10.
Figure 3e is a scanning electron microscope image (thin film surface) of the aluminum oxide film obtained in Example 3-1-17.
Figure 3f is a ^1H -NMR spectrum of composition F obtained in Example 3-2-4 after vacuum drying.
Figure 3g is a scanning electron microscope photograph (thin film surface) of an aluminum oxide film obtained on a glass substrate by film formation by heating at 200°C in a nitrogen atmosphere in Example 3-2-1.
Figure 3h is a scanning electron microscope photograph (thin film cross-section) of an aluminum oxide film obtained on a glass substrate by film formation by heating at 200°C in a nitrogen atmosphere in Example 3-2-1.
Figure 3i is a scanning electron microscope photograph (thin film surface) of an aluminum oxide film obtained on a glass substrate by film formation by heating at 200°C in a nitrogen atmosphere in Example 3-2-2.
Figure 3j is a scanning electron microscope photograph (thin film cross-section) of an aluminum oxide film obtained on a glass substrate by film formation by heating at 200°C in a nitrogen atmosphere in Example 3-2-2.
Figure 4a is an IR spectrum of the alkali-free glass by the ATR method.
Figure 4b is an IR spectrum of an aluminum oxide thin film by the ATR method.
Figure 4c is an IR spectrum of an aluminum oxide thin film by the ATR method.
Figure 4d is an IR spectrum of an aluminum oxide thin film obtained by the ATR method.
Figure 5a is a drawing illustrating a spray film forming device.
FIG. 5b is a drawing illustrating an example of an embodiment of a solar cell device of the present invention 5.

<First aspect of the present invention>

[Solution containing alkyl aluminum]

The first aspect of the first aspect of the present invention is an alkyl aluminum-containing solution containing an alkyl aluminum compound composed of dialkyl aluminum, trialkyl aluminum or a mixture thereof (provided that the alkyl group has 1 to 6 carbon atoms and may be the same or different) and a solvent. The solvent is an organic compound (cyclic amide compound) having a boiling point of 160° C. or higher, an amide structure represented by the following general formula (4), and a cyclic structure:

.

The solution containing an alkyl aluminum compound of the present invention can chemically stabilize an alkyl aluminum compound that is a dialkyl aluminum, a trialkyl aluminum or a mixture thereof by containing the cyclic amide compound as a solvent. The reason why the cyclic amide compound is preferable as the solvent is not clear, but it is presumed that the stability to air is greatly improved by the coordination bond of the unshared electron pair of oxygen and nitrogen in the amide structure, which is difficult to volatilize at a high boiling point, to aluminum, the reduction in volume increase due to the cyclic structure, and the increase in rigidity due to the cyclic structure. Usually, a compound having an amide structure reacts with an alkyl aluminum compound. Therefore, in prior predictions, it was presumed that the alkyl aluminum compound would undergo a chemical change by mixing with the cyclic amide compound. However, it was found that, contrary to expectations, the alkyl aluminum compound and the cyclic amide compound did not react, and that the state of the alkyl aluminum compound was maintained.

Regarding the ratio of the alkyl aluminum compound and the cyclic amide compound in the solution of the present invention, it is preferable to contain 1 or more cyclic amide compounds in molar ratio with respect to the alkyl aluminum compound, from the viewpoint of keeping the alkyl aluminum compound chemically stable. By containing an amount of the cyclic amide compound exceeding 2.6 in molar ratio with respect to the alkyl aluminum compound, chemical changes such as spontaneous ignition of the solution can be suppressed.

The cyclic amide compound can be, for example, N-methyl-2-pyrrolidone, or 1,3-dimethyl-imidazolidinone, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, or a mixture thereof, with N-methyl-2-pyrrolidone being particularly preferred since it is inexpensively available.

The above dialkylaluminum and/or trialkylaluminum may be, for example, an alkyl aluminum compound represented by the following general formula (1) or (2):

(In the formula, R ¹ represents a methyl group or an ethyl group, and R ² represents a halogen, a methyl group, or an ethyl group.)

(In the formula, R ³ represents an isobutyl group and R ⁴ represents a halogen or an isobutyl group.)

Examples of compounds represented by the general formula (1) include, for example, trimethylaluminum, dimethylaluminum chloride, triethylaluminum, diethylaluminum chloride, etc. The alkylaluminum compound represented by the general formula (1) may be, in particular, triethylaluminum or trimethylaluminum.

Examples of compounds represented by general formula (2) include, for example, triisobutylaluminum, diisobutylaluminum chloride, etc. The alkyl aluminum compound represented by general formula (2) may be, in particular, triisobutylaluminum.

The content of the alkyl aluminum compound in the alkyl aluminum containing solution of the present invention is not particularly limited, but the higher the content of the alkyl aluminum compound in the alkyl aluminum containing solution, the higher the transport efficiency, and therefore, from the viewpoint of transport efficiency, it may be, for example, 15 mass% or more. However, as long as it is a mixture with a predetermined amount of a cyclic amide compound and maintains a chemically stable state, it is not intended to be limited to 15 mass% or more.

The concentration of the above alkyl aluminum compound is preferably 15 mass% or more from the viewpoint of providing a high-concentration solution when R ¹ of the general formula (1) is an ethyl group, and is preferably 21 mass% or less from the viewpoint of stability against air. When R ¹ is a methyl group, the concentration is preferably 15 mass% or more from the viewpoint of providing a high-concentration solution, and is preferably 21 mass% or less from the viewpoint of stability against air.

The concentration of the alkyl aluminum compound represented by the general formula (2) is preferably 30 mass% or more from the viewpoint of transport efficiency (provision of a high-concentration solution). On the other hand, considering stability to air, it is preferably 40 mass% or less.

The alkyl aluminum-containing solution of the present invention may further include a solvent other than the cyclic amide compound. By adding a solvent other than the cyclic amide compound, the polarity, viscosity, boiling point, economy, etc. can be adjusted. Examples of the solvent other than the cyclic amide compound include aliphatic hydrocarbons such as n-hexane, octane, and n-decane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, and ethyl cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, and cumene; hydrocarbon solvents such as mineral spirits, solvent naphtha, kerosene, and petroleum ether; ether solvents such as diethyl ether, tetrahydrofuran, diisopropyl ether, dioxane, di-n-butyl ether, dialkyl ethylene glycol, dialkyl diethylene glycol, and dialkyl triethylene glycol; glyme, diglyme, and triglyme solvents. The amount of a solvent other than the cyclic amide compound to be added is not limited as long as it does not interfere with the effect of the cyclic amide compound, and for example, it can be 100 parts by mass or less with respect to 100 parts by mass of the cyclic amide compound. However, the range that can be added varies depending on the type of the alkyl aluminum compound, the type of the cyclic amide compound, and the type of the solvent other than the cyclic amide compound.

The above-mentioned cyclic amide compound, and optionally, a solvent other than the cyclic amide compound, and the alkyl aluminum compound can be mixed in a reaction vessel under an inert gas atmosphere, and each can be introduced according to any conventional method. The alkyl aluminum compound can also be introduced into the reaction vessel as a mixture with an organic solvent other than the cyclic amide compound.

The order of introduction into the mixing vessel may be any of the following: the alkyl aluminum compound, the cyclic amide compound, and, if necessary, a solvent other than the cyclic amide compound, or the cyclic amide compound, and, if necessary, a solvent other than the cyclic amide compound, the alkyl aluminum, or all introduced simultaneously.

The introduction time into the mixing vessel can be appropriately set depending on the type or capacity of the raw material to be mixed, but can be performed for, for example, between 1 minute and 10 hours. The temperature at the time of introduction can be selected at any temperature between -15 and 150°C. However, considering safety such as the elimination of the risk of ignition at the time of introduction, the range is preferably between -15 and 80°C.

When introducing raw materials into a mixing vessel, the stirring process after introduction may be either a batch operation, a semi-batch operation, or a continuous operation.

The alkyl aluminum containing solution of the present invention is useful as a material that can be used in air, for example, in the following applications.

·Alkylating agents such as methylation and ethylation in organic synthesis,

·Catalysts, semi-catalysts of special polymers,

·Reducing agent using diisobutyl aluminum hydride in organic synthesis

[Solution containing alkyl aluminum partial hydrolyzate]

The second aspect of the first aspect of the present invention is a solution containing an alkyl aluminum partial hydrolyzate, which contains a partial hydrolyzate of an alkyl aluminum compound composed of dialkyl aluminum, trialkyl aluminum or a mixture thereof (provided that the alkyl group has 1 to 6 carbon atoms and may be the same or different), and a solvent. The solvent is an organic compound (cyclic amide compound) having a boiling point of 160°C or higher, an amide structure represented by the following general formula (4), and a cyclic structure. In addition, the partial hydrolyzate is one obtained by hydrolyzing water in a molar ratio of 0.5 to 1.3 with respect to aluminum in the alkyl aluminum compound.

The cyclic amide compound is similar to the compound described in the first aspect of the first aspect of the present invention and may be N-methyl-2-pyrrolidone, or 1,3-dimethyl-imidazolidinone, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, or a mixture thereof.

The above dialkyl aluminum and/or trialkyl aluminum may be an alkyl aluminum compound represented by the general formula (1) or (2). The alkyl aluminum compound represented by the general formula (1) or (2) is also similar to the compound described in the first aspect of the first aspect of the present invention.

It is preferable that the above trialkyl aluminum is an alkyl aluminum compound represented by the following general formula (3):

(In the formula, R ⁵ represents a methyl group, an ethyl group, or an isobutyl group.)

Examples of compounds represented by general formula (3) include trimethylaluminum, triethylaluminum, triisobutylaluminum, etc. From the viewpoint of low price per unit mass of aluminum, triethylaluminum is preferable.

The above-mentioned cyclic amide compound is preferably used in a molar ratio of 1 or more to aluminum in the above-mentioned alkyl aluminum compound, from the viewpoint of obtaining a chemically stable solution containing a partial hydrolyzate. In addition, by making the alkyl aluminum compound a partial hydrolyzate, the chemical stability against air is improved, but since the stability is still lacking, from the viewpoint of obtaining a chemically stable solution containing a partial hydrolyzate, it is preferable to use it as a mixture with a predetermined amount of the cyclic amide compound.

The solution containing the partial hydrolyzate of the present invention may further contain a solvent other than the cyclic amide compound. The type and amount of the solvent other than the cyclic amide compound are the same as those described in the first aspect of the first aspect of the present invention.

Partial hydrolysis of the alkyl aluminum compound is performed using water or a solution containing water, at a molar ratio of 0.5 to 1.3 to the alkyl aluminum compound. If the molar ratio of water to the alkyl aluminum compound is less than 0.5, the solution remains in a liquid state even after drying the solvent, making it difficult to easily form a uniform aluminum oxide film. From the viewpoint of forming a uniform aluminum oxide film, it is more preferable that the molar ratio of water to the alkyl aluminum compound is 0.8 or more. On the other hand, if the molar ratio of water to the alkyl aluminum compound exceeds 1.3, a gel or solid insoluble in the solvent is precipitated, making it difficult to form a uniform aluminum oxide film by the gel or solid. The precipitated gel or solid can be removed by filtration, but this is not preferable because it leads to a loss of aluminum content.

The above partial hydrolysis reaction is carried out by adding water or a solution containing water to a solution of the alkyl aluminum compound dissolved in the cyclic amide compound, and optionally, a solvent other than the cyclic amide compound, under an inert gas atmosphere. Water itself may be added, but it is preferable to carry out the reaction by adding a solution containing water in terms of controlling the heat generation during the reaction of the alkyl aluminum compound and water.

The concentration of the alkyl aluminum compound in the above alkyl aluminum compound solution to which water or a solution containing water is added can be 0.1 to 50 mass%, and is preferably in the range of 0.1 to 30 mass%.

The addition of water or a solution containing water to the above alkyl aluminum compound solution can be appropriately set according to the type or capacity of the raw material to be mixed, and can be, for example, in the range of 1 minute to 10 hours. The temperature at the time of addition can be selected from any temperature between -15 and 150°C. However, considering safety, etc., the range is preferably -15 to 80°C.

After addition of water or a solution containing water, a maturing reaction may be performed for 0.1 to 50 hours to further promote partial hydrolysis of the alkyl aluminum compound and water. The maturing reaction temperature may be selected at any temperature between -15 and 150°C. However, considering shortening of the maturing reaction time, etc., the temperature is preferably in the range of 25 to 150°C.

The above-mentioned cyclic amide compound, and optionally, a solvent other than the cyclic amide compound, an alkyl aluminum compound, water, or a solution containing water, can be introduced into the reaction vessel according to any conventional method. The pressure of the reaction vessel is not limited. The hydrolysis reaction process may be any of a batch operation, a semi-batch operation, and a continuous operation, and there is no particular limitation, but a batch operation is preferred.

By the above partial hydrolysis reaction, a solution containing the above alkyl aluminum partial hydrolyzate is obtained. When the alkyl aluminum compound is trimethyl aluminum, triethyl aluminum, or triisobutyl aluminum, analysis on the partial hydrolysis composition has been performed for a long time, but the composition results of the product differ depending on the report, and the composition of the product is not clearly specified. In addition, the composition of the product also changes depending on the solvent, concentration, molar ratio of water added, addition temperature, reaction temperature, reaction time, etc.

The alkyl aluminum partial hydrolysate in the method of the present invention is presumed to be a mixture of compounds including a structural unit represented by the following general formula (5):

(In the formula, R ⁵ is the same as R ⁵ in general formula (3), and m is an integer from 1 to 80.)

After the above partial hydrolysis reaction is completed, if a trace amount of solids, etc. are precipitated, the solids, etc. can be removed by purification using a method such as filtration or chromatography.

The above solution containing the alkyl aluminum partial hydrolyzate can have its solid concentration adjusted by concentration (solvent removal). In addition, the solid concentration, polarity, viscosity, boiling point, economy, etc. can be appropriately adjusted by adding a solvent used in the reaction or a solvent different from the one used in the reaction.

Examples of solvents other than those used in the reaction include aliphatic hydrocarbons such as n-hexane, octane, and n-decane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, and cumene; hydrocarbon solvents such as mineral spirits, solvent naphtha, kerosene, and petroleum ether; ethers such as diethyl ether, tetrahydrofuran, diisopropyl ether, dioxane, di-n-butyl ether, dialkyl ethylene glycol, dialkyl diethylene glycol, and dialkyl triethylene glycol; glyme, diglyme, and triglyme solvents, etc.

The content of the alkyl aluminum partial hydrolysate in the solution containing the alkyl aluminum partial hydrolysate of the present invention can be appropriately determined depending on the intended use. The content can be adjusted by adjusting the amount of the cyclic amide compound and/or the amount of a solvent other than the cyclic amide compound. The content of the alkyl aluminum partial hydrolysate can be appropriately adjusted within a range of, for example, 0.1 to 50 mass%. However, it is not intended to be limited to this range.

[Method for producing aluminum oxide thin film]

The method for producing an aluminum oxide thin film of the present invention is a method of obtaining an aluminum oxide thin film by applying a solution containing the alkyl aluminum partial hydrolyzate of the present invention to a substrate.

The coating on the above-mentioned substrate can be performed by a conventional method such as spin coating, immersion coating, screen printing, bar coating, slit coating, die coating, gravure coating, roll coating, curtain coating, spray pyrolysis, electrostatic spray pyrolysis, inkjet, or mist CVD.

The application to the above-mentioned substrate can be carried out in either an inert atmosphere or an air atmosphere, but from the standpoint of economy, it is preferable to carry out the application in an air atmosphere because the equipment is also simpler.

The application to the above-mentioned material can be carried out under either pressurized or reduced pressure, but from the standpoint of economy, it is preferable to carry out the application under atmospheric pressure because the apparatus is also simpler.

The above-described glass includes glass such as lead glass, soda glass, borosilicate glass, and non-alkali glass; oxides such as silica (SilicA), alumina, titania, zirconia, and complex oxides; Polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), polycarbonate (PC), polyphenylene sulfide (PPS), polystyrene (PS), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polyvinylidene chloride, cyclic polyolefin (COP), ethylene-vinyl acetate copolymer (EVA), polyimide, polyamide, polyether sulfone (PES), polyurethane, triacetate, triacetyl cellulose (TAC), cellophane, polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), perfluoroalkoxy fluorine resin (PFA), ethylene tetrafluoride and propylene hexafluoride copolymer (ETFE), Examples include polymers such as ethylene-chlorotrifluoroethylene copolymer (ECTFE).

The shape of the above-described material may include a powder, a film, a plate, or a three-dimensional structure having a three-dimensional shape.

After applying the solution containing the above-mentioned alkyl aluminum partial hydrolyzate, the substrate is brought to a predetermined temperature, and the solvent is dried, or the drying is performed simultaneously with firing at a predetermined temperature, thereby forming an aluminum oxide film. In addition, when the coating is performed by a spray pyrolysis method, an electrostatic spray pyrolysis method, an inkjet method, or a mist CVD method, since the substrate can be heated to a predetermined temperature before the coating, it is possible to dry the solvent simultaneously with the coating, or to fire simultaneously with the drying.

The temperature for drying the solvent may be any temperature selected from, for example, 20 to 250° C. The solvent may be dried for, for example, 0.5 to 60 minutes. However, the present invention is not intended to be limited to these ranges.

The predetermined temperature for sintering to form the above aluminum oxide can be selected at any temperature, for example, from 50 to 550°C. However, considering the type of the substrate, it is appropriate to set it to a temperature at which the substrate is not damaged. When the predetermined temperature for sintering is the same as the predetermined temperature for drying the solvent, drying of the solvent and sintering can be performed simultaneously. It is possible to sinter the solvent-dried precursor film for, for example, 0.5 to 300 minutes.

The film thickness of the aluminum oxide film obtained as described above can be, for example, 0.005 to 3 ㎛. The film thickness of the aluminum oxide film can be increased, if necessary, by repeating the above-described coating, drying, and baking processes multiple times.

If necessary, the aluminum oxide film obtained as described above can be heated at a predetermined temperature in an oxidizing gas atmosphere such as oxygen, a reducing gas atmosphere such as hydrogen, a steam atmosphere containing a large amount of moisture, or a plasma atmosphere such as argon, nitrogen, or oxygen, thereby improving the crystallinity and density of the aluminum oxide film. Residual organic substances, etc. in the obtained aluminum oxide film can be removed by light irradiation such as ultraviolet rays or microwave treatment.

<Second aspect of the present invention>

A method for manufacturing an article having an aluminum oxide film of the present invention comprises the following processes (A), (B) and (C).

(A) A process for obtaining a composition containing a partial hydrolyzate of an organoaluminum compound represented by the following general formula (6) by partially hydrolyzing the organoaluminum compound in an organic solvent (provided that the partial hydrolysis is performed using water having a molar ratio of 0.4 to 1.3 with respect to the organoaluminum compound).

(B) a process of forming a coating film by applying the composition containing the above-mentioned partial hydrolyzate to at least a portion of the surface of a substrate under an inert gas atmosphere;

(C) A process of forming an aluminum oxide film by heating the substrate on which the above coating film has been formed at a temperature of 400°C or lower under an inert gas atmosphere:

(In the formula, R ¹ represents hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, and R ² and R ³ independently represent hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, a straight-chain or branched alkoxyl group having 1 to 7 carbon atoms, an acyloxy group, or an acetylacetonate group.)

Process (A)

In process (A), an organoaluminum compound represented by general formula (6) is partially hydrolyzed in an organic solvent to obtain a composition containing a partial hydrolyzate of the organoaluminum compound.

Specific examples of the straight-chain or branched alkyl group having 1 to 4 carbon atoms represented as R ¹ in the organoaluminum compound represented by the general formula (6) include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. In the compound represented by the general formula (6), it is preferable that R ¹ is a compound having 1, 2, 3, or 4 carbon atoms. In the compound represented by the general formula (6), it is particularly preferable that R ¹ is an ethyl group having 2 carbon atoms. The straight-chain or branched alkyl group having 1 to 4 carbon atoms represented as R ² and R ³ is the same as the R ¹ above.

Specific examples of the straight-chain or branched alkoxyl group having 1 to 7 carbon atoms represented by R ² and R ³ in the organoaluminum compound represented by general formula (6) include a methoxy group, an ethoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a t-butoxy group, a phenoxy group, a methoxyethoxy group, and the like. Specific examples of the acyloxy group include an acetoxy group, a propionyloxy group, a butyryloxy group, an isobutyryloxy group, and the like.

Among the compounds represented by the general formula (6), trimethylaluminum, triethylaluminum, diethylaluminum ethoxide, triisobutylaluminum, and tri-n-butylaluminum are preferable because they are inexpensive and easily available, and in particular, trimethylaluminum, triethylaluminum, diethylaluminum ethoxide, and triisobutylaluminum are preferable because they are inexpensive, are used in large quantities as a polymerization promoter, and are easy to obtain, and among these, triethylaluminum is preferable because it is inexpensive, is used in the largest quantity as a polymerization promoter, and is easy to obtain.

These compounds are generally available as commercial products, and it is known that they contain traces or small amounts of alkyl groups having a different number of carbon atoms than R ¹ , R ^{2 ,} and R ³ , or hydrogen in the organoaluminum compound. For example, triethylaluminum suitable for the present invention contains an n-butyl group, hydrogen, etc. in addition to an ethyl group, which is the majority of the alkyl groups in R ¹ , R ^{2 ,} and R ³ , and these can be used without problems in the present invention.

The above partial hydrolysis is performed using water having a molar ratio of 0.4 to 1.3 to the organoaluminum compound. When the molar ratio of water to the organoaluminum compound is less than 0.4, it is difficult to form an aluminum oxide film having good quality (transparent and having good adhesion to the substrate) in the coating step (B) and the heating step (C) which are performed in an inert gas atmosphere that substantially does not contain an oxygen source such as moisture or oxygen. When the molar ratio of water to the organoaluminum compound exceeds 1.3, a gel-like substance insoluble in an organic solvent is precipitated, which hinders the formation of a homogeneous aluminum oxide film.

The molar ratio of water to the organoaluminum compound is preferably in the range of 0.4 to 1.25. The composition for forming an aluminum oxide film obtained by hydrolyzing the organoaluminum compound in the range of the amount of water added can form an aluminum oxide film of good quality (transparent and having good adhesion to a substrate) by coating and heating in an inert gas atmosphere. Here, the inert gas atmosphere is an atmosphere composed of an inert gas that substantially does not contain an oxygen source such as moisture or oxygen, and for example, represents an atmosphere in which moisture and oxygen are each 1000 ppm or less, preferably 400 ppm or less. The moisture content in the inert gas atmosphere can be controlled by the dew point temperature, and when it is 400 ppm or less, it can be controlled in the range of, for example, 5 ppm (dew point temperature -66°C) to 375 ppm (dew point temperature -30°C). In addition, considering the ease of operation, it can be controlled to be in the range of 100 ppm (dew point temperature -42℃) to 375 ppm (dew point temperature -30℃). There is no particular limitation on the type of inert gas, but examples include helium, argon, and nitrogen. Among these, nitrogen is particularly preferable in terms of cost.

The organic solvent used in the preparation of the above partial hydrolyzate may be any solvent that is soluble in the organoaluminum compound represented by the general formula (6), and examples thereof include an electron-donating organic solvent or a hydrocarbon compound. In addition, the organic solvent may be one that is soluble in water, or an organic solvent that is soluble in water and one that is low in solubility in water may be used in combination. The organic solvent may be an electron-donating organic solvent, a hydrocarbon compound, or a mixture thereof.

Examples of electron-donating organic solvents include ether solvents such as 1,2-diethoxyethane, 1,2-dibutoxyethane, diethyl ether, di-n-propyl ether, diisopropyl ether, dibutyl ether, cyclopentyl methyl ether, tetrahydrofuran, dioxane, glyme, diglyme, triglyme, anisole, and methoxytoluene; and amine solvents such as trimethylamine, triethylamine, and triphenylamine. Preferred organic solvents having electron-donating properties are 1,2-diethoxyethane, tetrahydrofuran, and dioxane.

As the hydrocarbon compound, examples thereof include straight-chain, branched hydrocarbon compounds or cyclic hydrocarbon compounds having 5 to 20 carbon atoms, more preferably 6 to 12 carbon atoms, aromatic hydrocarbon compounds having 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms, and mixtures thereof.

Specific examples of these hydrocarbon compounds include aliphatic hydrocarbons such as pentane, n-hexane, heptane, isohexane, methylpentane, octane, 2,2,4-trimethylpentane (isooctane), n-nonane, n-decane, n-hexadecane, octadecane, eicosane, methylheptane, 2,2-dimethylhexane, and 2-methyloctane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, and ethyl cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, cumene, and trimethylbenzene; and hydrocarbon solvents such as mineral spirits, solvent naphtha, kerosene, and petroleum ether.

In the composition containing the partial hydrolyzate obtained in process (A), when R ¹ , R ² , and R ³ remaining in the composition after partial hydrolysis by water do not contain hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, an alcohol such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, isobutyl alcohol, n-butyl alcohol, and diethylene glycol can be used as a solvent that can coexist in the composition.

The above partial hydrolysis is performed by adding water to a solution of a compound represented by the general formula (6) dissolved in the organic solvent, or by mixing water with an organic solvent solution of a compound represented by the general formula (6). The concentration of the compound represented by the general formula (6) in the solution is appropriately determined in consideration of the solubility in the organic solvent and the concentration of the partial hydrolyzate in the obtained partial hydrolyzate composition, but is suitably set to a range of, for example, 0.1 to 50 mass%, and preferably 0.1 to 35 mass%.

The addition or mixing of water can be carried out without mixing the water with another solvent, or after mixing the water with another solvent. The addition or mixing of water can be carried out for, for example, 60 seconds to 10 hours, depending on the scale of the reaction. From the viewpoint of a good yield of the partial hydrolyzate, it is preferable to add water by dropping it into the organoaluminum compound of the general formula (6), which is the raw material. The addition of water can be carried out, for example, without stirring the solution of the compound represented by the general formula (6) and the electron-donating organic solvent (in a stationary state) or while stirring. The temperature at the time of addition can be selected at any temperature between -90 and 150°C. From the viewpoint of the reactivity of water and the organoaluminum compound, -15 to 30°C is preferable.

After the addition of water, in order to further progress the hydrolysis reaction between water and the compound represented by the general formula (6), the mixture can be left without stirring (in a stationary state) for, for example, 1 minute to 48 hours, or can be stirred. With regard to the reaction temperature, the reaction can be carried out at any temperature between -90 and 150°C. A temperature of -15 to 80°C is preferable from the viewpoint of obtaining a high yield of a partial hydrolyzate. The pressure in the hydrolysis reaction is not limited. Usually, it can be carried out at normal pressure (atmospheric pressure). The progress of the hydrolysis reaction between water and the compound represented by the general formula (6) can be monitored by sampling the reaction mixture, analyzing the sample by NMR or IR, etc., or sampling the generated gas, as necessary.

The above organic solvent, the organic aluminum compound of the general formula (6) as a raw material, and water can be introduced into the reaction vessel according to any conventional method, and the organic aluminum compound and water can also be introduced as a mixture with the organic solvent, respectively. The hydrolysis reaction process may be any of a batch operation type, a semi-batch operation type, and a continuous operation type, and there is no particular limitation, but a batch operation type is preferred.

By the above hydrolysis reaction, the organoaluminum compound of the general formula (6) is partially hydrolyzed by water, and a product including a partial hydrolyzate is obtained. When the organoaluminum compound of the general formula (6) is trimethylaluminum or triethylaluminum, analysis on the hydrolyzate has been performed for a long time. However, the results differ depending on the report, and the composition of the product is not clearly specified. In addition, the composition of the product can change depending on the molar ratio of water added, the reaction time, etc. The main component of the product in the method of the present invention is a partial hydrolyzate, and the partial hydrolyzate is presumed to be a mixture of compounds including a structural unit represented by the following general formula (7):

(In the formula, Q is the same as any one of R ¹ , R ² , and R ³ in general formula (6), and m is an integer from 1 to 200.)

After completion of the hydrolysis reaction, part or all of the product can be recovered and/or purified by a general method such as filtration, concentration, extraction, or column chromatography. In conditions where the molar ratio of water to the organoaluminum compound of the general formula (6) is relatively high, insoluble matters may be generated, and in this case, it is preferable to obtain a composition containing a partial hydrolyzate that is substantially free of insoluble matters by filtering using a filter having a pore diameter of, for example, 3 µm or less.

The partial hydrolysate (solid content) recovered by separation from the organic solvent by the above method can be dissolved in an organic solvent for film-forming, which is different from the organic solvent used in the reaction, to prepare a composition for application. However, the composition containing the partial hydrolysate, which is a reaction product mixture, can be prepared as is or by appropriately adjusting the concentration to prepare a composition for application without separation from the organic solvent.

Examples of organic solvents that can be used as the organic solvent for film coating formation include straight-chain, branched hydrocarbon compounds or cyclic hydrocarbon compounds having 5 to 20 carbon atoms, more preferably 6 to 12 carbon atoms, aromatic hydrocarbon compounds having 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms, and mixtures thereof.

Specific examples of these hydrocarbon compounds include aliphatic hydrocarbons such as pentane, n-hexane, heptane, isohexane, methylpentane, octane, 2,2,4-trimethylpentane (isooctane), n-nonane, n-decane, n-hexadecane, octadecane, eicosane, methylheptane, 2,2-dimethylhexane, and 2-methyloctane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, and ethyl cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, cumene, and trimethylbenzene; and hydrocarbon solvents such as mineral spirits, solvent naphtha, kerosene, and petroleum ether.

Other examples of organic solvents that can be used as organic solvents for film coating formation include ether solvents such as 1,2-diethoxyethane, 1,2-dibutoxyethane, diethyl ether, di-n-propyl ether, diisopropyl ether, dibutyl ether, cyclopentyl methyl ether, tetrahydrofuran, dioxane, glyme, diglyme, triglyme, anisole, and methoxytoluene; and amine solvents such as trimethylamine, triethylamine, and triphenylamine.

In addition, these organic solvents can be used alone or in combination of two or more types.

In addition, in the composition for forming an aluminum oxide film, when R ¹ , R ² , and R ³ remaining in the composition after hydrolysis are alkoxide groups, alcohols that can coexist in the composition, such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, isobutyl alcohol, n-butyl alcohol, and diethylene glycol, can also be used as organic solvents for forming a film.

The solid content concentration of the partial hydrolyzate of the composition containing the partial hydrolyzate obtained in process (A) may be, for example, in the range of 0.1 to 30 mass%. The higher the concentration, the fewer the number of coatings can be applied to produce a film. However, considering the solubility of the reaction product containing the partial hydrolyzate of the organoaluminum compound, for example, the ease of forming an aluminum oxide film, the solid content concentration may preferably be 0.1 to 25 mass%, more preferably 0.1 to 15 mass%.

The composition containing the partial hydrolyzate obtained in the above process (A) corresponds to the composition for forming an aluminum oxide film of the present invention. The composition for forming an aluminum oxide film of the present invention can form an aluminum oxide film of good quality (transparent and having good adhesion to a substrate) on a substrate by performing film coating formation in an inert gas atmosphere. This manufacturing method includes steps (B) and (C). Steps (B) and (C) are described below.

Process (B)

A composition containing a partial hydrolyzate obtained in process (A) is applied to at least a portion of the surface of a substrate under an inert gas atmosphere to form a coating film.

There is no particular limitation on the method of applying the composition to the surface of the substrate, and for example, conventional methods such as spray coating, immersion coating, spin coating, slit coating, slot coating, bar coating, roll coating, curtain coating, spray pyrolysis, electrostatic coating, inkjet, and screen printing can be used.

Spray pyrolysis or electrostatic coating is a method that can perform coating and film formation simultaneously while heating the substrate. Therefore, the solvent can be dried in parallel with the coating, and depending on the conditions, heating for solvent drying may not be necessary. Furthermore, depending on the conditions, in addition to drying, the reaction of the partial hydrolyzate with aluminum oxide may also proceed at least partially. Therefore, in some cases, the formation of an aluminum oxide film by heating in the post-process (C) may be performed more easily. The heating temperature of the substrate during coating and film formation in the spray pyrolysis method may be, for example, in the range of 20 to 400°C, preferably 50 to 400°C. In particular, when a substrate with low heat resistance such as a resin is used, the heating may be performed in the range of 20 to 350°C, and when the heat resistance is further low, in the range of 20 to 250°C.

The application of the composition to the substrate surface is carried out under an inert gas atmosphere such as nitrogen. In the present invention, the application of the partially hydrolyzed product-containing composition is carried out under an inert gas atmosphere, whereby it becomes possible to form an aluminum oxide film that satisfies all of the following requirements: 1) low temperature deposition temperature, 2) adhesion to the substrate, and 3) oxide formation state (for example, transparency or homogeneity of the oxide film). The inert gas atmosphere is an atmosphere composed of an inert gas that substantially does not contain an oxygen source such as moisture or oxygen, and for example, represents an atmosphere in which moisture and oxygen are each 1000 ppm or less, preferably 400 ppm or less. The moisture content in the inert gas atmosphere can be controlled by the dew point temperature, and when it is 400 ppm or less, it can be controlled in the range of, for example, 5 ppm (dew point temperature -66°C) to 375 ppm (dew point temperature -30°C). In addition, considering the ease of operation, it can be controlled to be in the range of 100 ppm (dew point temperature -42℃) to 375 ppm (dew point temperature -30℃).

Meanwhile, in the case where there is no moisture or oxygen at all, in the structure of the partial hydrolyzate represented by the general formula (7), the Al-Q site may remain unreacted and in the film, so the coexistence of moisture and oxygen is permitted within a range where the desired physical properties, such as the homogeneity of the obtained film, are not impaired. Specifically, the moisture and oxygen in the inert gas atmosphere can be each 1000 ppm or less, preferably 400 ppm or less.

When the moisture or oxygen in the inert gas atmosphere is greater than the aforementioned value during this application or subsequent solvent drying, especially in a situation where the solvent remains, the reaction between the partial hydrolyzate and the moisture and oxygen proceeds excessively, causing the attachment to become powdery before film formation, or the transparency of the film to be impaired, thereby deteriorating the homogeneity and adhesion of the obtained aluminum oxide film, which is not preferable.

There is no particular limitation on the inert gas, but examples include helium, argon, and nitrogen. Among these, nitrogen is particularly preferable in terms of cost. In addition, regarding the pressure at the time of application, it can be carried out under any of atmospheric pressure, pressurized pressure, and reduced pressure, but it is usually preferable to carry out the application under atmospheric pressure because it is simple in terms of equipment and does not incur costs.

In Fig. 2a, a spray film-forming device is shown as an example of a spray film-forming device that can be used in the present invention. In the drawing, (1) represents a spray bottle filled with a coating liquid, (2) represents a substrate holder, (3) represents a spray nozzle, (4) represents a compressor, and (5) represents a substrate. In spray coating, the substrate is installed in the substrate holder (2), and, if necessary, is heated to a predetermined temperature using a heater, and then, in an inert gas atmosphere, compressed inert gas and the coating liquid are simultaneously supplied from a spray nozzle (3) arranged above the substrate to atomize and spray the coating liquid, thereby applying a partially hydrolyzed product-containing composition of the present invention onto the substrate (step (B)).

Considering the adhesion to the substrate, the ease of evaporation of the solvent, etc., it is preferable that the spray application of the coating solution be ejected from the spray nozzle so that the droplet size is in the range of 30 ㎛ or less. In addition, considering that the solvent evaporates to some extent before reaching the substrate, thereby reducing the size of the droplet, it is preferable that the distance between the spray nozzle and the substrate be within 50 cm from the viewpoint of being able to form a coating film of the partially hydrolyzed product-containing composition.

In addition, without heating the substrate and the ambient temperature, a coating film of a partially hydrolyzed product-containing composition can be formed on the substrate simply by simultaneously supplying a compressed inert gas and a coating liquid from a spray nozzle (3) arranged above the substrate and atomizing and spraying the coating liquid. In addition, although either of the coatings in the method of the present invention can be performed under pressurized or reduced pressure, performing it under atmospheric pressure is preferable because it is simple in terms of equipment and does not incur costs.

In the above manufacturing method, there are no restrictions on the material, shape, size, etc. of the substrate for forming the aluminum oxide film. Examples of the material include inorganic materials such as glass, metal, and ceramics, resinous substrates such as plastic, organic materials such as paper and wood, and composites thereof.

These materials are not particularly limited as long as they do not interfere with the formation of the aluminum oxide film. For example, examples of glasses include quartz glass, borosilicate glass, soda glass, non-alkali glass, lead glass, etc., and oxides such as sapphire. In addition, examples of metals include stainless steel such as SUS304 and SUS316, aluminum, iron, copper, titanium, silicon, nickel, gold, silver, and alloys containing these. Examples of ceramics include oxides such as alumina, silica, zirconia, and titania, nitrides such as boron nitride, aluminum nitride, silicon nitride, titanium nitride, and gallium nitride, carbon compounds such as silicon carbide, and composites containing these. In addition, polymers forming plastics include polyester (e.g., polyethylene terephthalate (PET), polyethylene naphthalate (PEN), poly(meth)acrylic (e.g., polymethyl methacrylate (PMMA)), polycarbonate (PC), polyphenylene sulfide (PPS), polystyrene, polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polyvinylidene chloride, polyethylene (PE), polypropylene (PP), cyclic polyolefin (COP), ethylene-vinyl acetate copolymer (EVA), polyimide, polyamide, polyaramid, polyether sulfone (PES), polyurethane, triacetate, triacetyl cellulose (TAC), cellophane fluororesin (e.g., polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), Examples of the resins include perfluoroalkoxyfluorine resin (PFA), ethylene tetrafluoride/propylene hexafluoride copolymer (FEP), ethylene tetrafluoride ethylene copolymer (ETFE), ethylene chlorotrifluoroethylene copolymer (ECTFE), etc., and composite resins containing these. Among these, EVA, COP, PP, PE, PET, PPS, PEN, PC, PMMA, PES, polyimide, polyamide, aramid, PVC, and PVA are preferable.

In addition, as the shape of these materials, for example, a film shape, a plate shape, a three-dimensional structure having an arbitrary shape, and a composite thereof can be used.

Additionally, these materials may be transparent, translucent, or opaque.

For example, as a transparent substrate in the form of a film, an inorganic material such as sheet glass or an organic material such as a plastic film as a polymer substrate can be exemplified. When the substrate is a plastic film, it can be either a non-stretched film or a stretched film depending on the type of polymer. For example, a polyester film, such as a PET film, is usually a biaxially stretched film, and a PC film, a triacetate film, a cellophane film, etc. are usually non-stretched films.

As an opaque substrate, a wafer or sheet of metal or metal oxide, nitride, carbon compound, or a polymer substrate such as polyimide, polyamide, aramid, carbon fiber, PP, PE, PET sheet, or non-woven fabric can be used.

In addition to these materials, a coating film can also be formed on functional materials such as electronic device films, such as electrodes, semiconductors, and insulators, which are formed from inorganic substances such as metals, oxides, nitrides, and carbon compounds, organic substances such as low molecules and polymers, and composites of the aforementioned inorganic and organic substances.

Process (C)

In process (C), the substrate on which the coating film has been formed is heated at a temperature of 400°C or lower in an inert gas atmosphere to form an aluminum oxide film.

After applying the coating liquid to the surface of the substrate, the substrate is dried at a predetermined temperature and the solvent is then heated to a predetermined temperature simultaneously with the drying, thereby forming an aluminum oxide film. However, the drying of the solvent has actually already partially progressed in step (B). In particular, when the coating in step (B) is performed at a relatively high temperature, there are cases where the drying of the solvent in step (B) is almost complete.

The conditions for drying the solvent can be set appropriately according to the type or boiling point (vapor pressure) of the coexisting organic solvent. The temperature for drying the solvent can be, for example, in the range of 20 to 350°C, and when the boiling point of the solvent is 200°C or lower, it can be 20 to 250°C, and when the boiling point of the solvent is 150°C or lower, it can be 20 to 200°C, and the drying time can be usually 0.2 to 300 minutes, and preferably 0.5 to 120 minutes. These conditions can also be considered when drying the solvent is performed at least partially in the step (B). It is also possible to perform solvent drying and aluminum oxide film formation simultaneously by making the solvent drying temperature and the subsequent heating temperature for forming an aluminum oxide film the same, and the temperature at that time is usually set to the heating temperature for forming an aluminum oxide film.

In the present invention, the heating temperature for forming an aluminum oxide film after solvent drying is, for example, in the range of 20 to 400°C, more preferably 20 to 350°C, and the treatment at this temperature can be performed at least once. The heating time at this heating temperature is usually in the range of 0.2 to 300 minutes, preferably 0.5 to 120 minutes. The heating time can be appropriately determined in consideration of the state of formation of the aluminum oxide film by heating.

In particular, in the present invention, since it is possible to use heat treatment at a low temperature of 350°C or lower in drying the solvent or the subsequent heat treatment, and since treatment is possible in a short period of time, film formation is possible when a substrate with low heat resistance such as a resin is used as the substrate, or when there is a problem in the treatment of applying heat or high energy to a functional material such as an electronic device film such as an electrode, a semiconductor, an insulator, etc. formed from an inorganic substance such as a metal, oxide, nitride, or carbon compound, or an organic substance such as a low molecule or polymer, or a composite of the above-mentioned inorganic and organic substances.

This process (C) is also performed under an inert gas atmosphere. By performing the heating in the process (C) under an inert gas atmosphere, it becomes possible to form an aluminum oxide film that satisfies all of 1) low temperature of the film formation temperature, 2) adhesion to the substrate, and 3) formation state of the oxide (for example, transparency or homogeneity of the oxide film). The inert gas atmosphere is an atmosphere composed of an inert gas that does not substantially contain an oxygen source such as moisture or oxygen, and for example, represents an atmosphere in which moisture and oxygen are each 1000 ppm or less, preferably 400 ppm or less. The moisture content in the inert gas atmosphere can be controlled by the dew point temperature, and when it is 400 ppm or less, it can be controlled in the range of, for example, 5 ppm (dew point temperature -66°C) to 375 ppm (dew point temperature -30°C). In addition, considering the ease of operation, it can be controlled to be in the range of 100 ppm (dew point temperature -42℃) to 375 ppm (dew point temperature -30℃).

As in process (B), in process (C), in the case where there is no moisture or oxygen at all, in the structure of the partial hydrolyzate represented by general formula (7), there is a case where the Al-Q site remains unreacted and remains in the film, so the coexistence of moisture and oxygen is permitted within a range where the desired physical properties, such as the homogeneity of the obtained film, are not impaired. Specifically, the moisture and oxygen in the inert gas atmosphere can be each 1000 ppm or less, preferably 400 ppm or less.

In process (C), in a situation where a solvent remains during heating, if the moisture or oxygen in the inert gas atmosphere is greater than the aforementioned value, the reaction between the partial hydrolyzate and the moisture and oxygen proceeds excessively, so that the attachment becomes powdery before film formation, or the transparency of the film is impaired, and the homogeneity or adhesion of the obtained aluminum oxide film deteriorates, which is not preferable.

In the process (C), an aluminum oxide film adhered to the surface of the substrate is formed by heating at 400°C or lower. There is no particular limitation on the film thickness of the aluminum oxide film, but in practice, it can be in the range of 0.001 to 5 μm, typically 0.01 to 5 μm. According to the manufacturing method of the present invention, a film having a film thickness in the above range can be appropriately manufactured by repeating the above-described coating (drying) heating one or more times. In addition, in principle, by repeating the number of coatings and/or increasing the coating time, it is also possible to form a film having a thickness of 5 μm or more.

In addition, solvent drying or heating in all methods that can be used in the present invention can be performed under pressurized or reduced pressure, but it is preferable to perform the process at atmospheric pressure because it is simple in terms of equipment and does not incur costs.

The "aluminum oxide" obtained by the manufacturing method of the present invention is a compound containing aluminum elements and oxygen elements, and refers to one in which the proportion of these two elements in the aluminum oxide is 90% or more. In addition to aluminum and oxygen, it may contain hydrogen or carbon. In addition, the "aluminum oxide film" manufactured by heating at a temperature of 400°C or lower in the process (C) of the present invention is usually in an amorphous state, as no clear peak is observed in X-ray diffraction analysis.

The amorphous aluminum oxide film formed in the process (C) can have its crystallinity improved by heating separately or continuously at a temperature exceeding 400°C. For example, crystallization can be performed by heat treatment at a heating temperature and treatment atmosphere similar to that at which aluminum oxide generally known to crystallize into crystalline alumina or the like at 1000°C or higher.

In addition, the aluminum oxide film obtained in process (C) can further improve crystallinity, if necessary, under an oxidizing gas atmosphere such as moisture, oxygen, or ozone, under a reducing gas atmosphere such as hydrogen, or under a plasma atmosphere such as hydrogen, argon, or oxygen.

The partially hydrolyzed product-containing composition obtained in step (A) of the manufacturing method of the present invention is (a) a composition in which partial hydrolysis is performed using water having a molar ratio of 0.4 to 1.3 with respect to the organoaluminum compound, and (b) this composition can be used to form an aluminum oxide film in which film coating and formation are performed under an inert gas atmosphere. When film formation by coating and heating under an inert gas atmosphere (equivalent to steps (B) and (C)) is performed, an aluminum oxide film having excellent adhesion to a substrate and a good oxide formation state can be formed even at a low film formation temperature by only performing coating and heating. The aluminum oxide film itself obtained by using the composition for coating and forming an aluminum oxide film of the present invention has high adhesion to a substrate, and good adhesion can be obtained even on a substrate on which direct film formation of an oxide is usually difficult. However, if necessary, it is also possible to apply the film using a method that increases the adhesion of oxides formed on a generally known substrate, such as undercoat treatment, primer treatment, corona treatment, UV irradiation, and chlorination.

[Aluminum oxide film]

By using the composition for forming an aluminum oxide film of the present invention, an aluminum oxide film having excellent adhesion to a substrate and a good oxide formation state can be formed even at a low film formation temperature simply by performing coating and heating in the above-described inert gas atmosphere.

The manufactured aluminum oxide film, "aluminum oxide" in the present invention refers to a compound containing aluminum element and oxygen element, and the proportion of these two elements in the aluminum oxide is 90% or more. In addition, the "aluminum oxide film" manufactured at 400°C or lower in the present invention usually does not have a clear peak observed in X-ray diffraction analysis and is in an amorphous state.

These aluminum oxide films can also be crystallized by post-treatment after film formation, such as heating at a high temperature of 1000°C or higher, if the heat-resistant temperature of the substrate or the like allows it.

In addition, if necessary, after the aluminum oxide film is formed, it is possible to promote the formation of aluminum oxide or improve crystallinity by further performing the heating under an oxidizing gas atmosphere such as oxygen or a plasma atmosphere such as argon or oxygen. In addition, for the purpose of removing carbon components such as residual organic substances in the aluminum oxide film obtained in the present invention or improving the film quality of the aluminum oxide film, treatment using light irradiation such as ultraviolet rays or microwaves, which are generally used, may be performed.

This aluminum oxide film has different properties depending on the molar ratio of water added so as to obtain a partial hydrolyzate with respect to the organoaluminum compound in the partial hydrolyzate of the organoalkyl aluminum compound contained in the composition for producing the aluminum oxide film, the concentration of the partial hydrolyzate, the coexisting organic solvent, the film-forming conditions and method, etc., but in the coating film-forming method used in the present invention, a film can be obtained ranging from transparent with high transmittance to translucent and opaque, and the film thickness of the aluminum oxide film is not particularly limited, but is practically in the range of 0.001 to 10 µm, and in the range of 0.01 to 5 µm, and a film having high adhesion to a substrate such as glass or resin can be obtained.

The manufacturing method of the present invention includes performing the step (B) of applying the composition to the surface of a substrate under an inert gas atmosphere and the step (C) of heating the obtained coating once or twice or more. The operations of applying and heating the obtained coating can be performed as many times as necessary to obtain desired properties such as insulation or heat resistance, but can be performed appropriately in a range such as preferably 1 to 50 times, more preferably 1 to 30 times, and even more preferably 1 to 10 times.

[Functional film containing aluminum oxide]

The manufactured aluminum oxide film has excellent adhesion to a substrate, and the oxide formation state is good. Therefore, a composite (article) in which an aluminum oxide film is attached to a substrate, or a composite film having layers other than an aluminum oxide film and an aluminum oxide film can be attached to a substrate. The composite film can be used as a functional film containing aluminum oxide. For example, it can be provided for uses such as production of an alumina sheet for electronic materials, an aluminum oxide film, production of a catalyst carrier, imparting heat resistance, imparting barrier properties against air and moisture, imparting an antireflection effect, imparting an antistatic effect, imparting an antifogging effect, imparting wear resistance, etc., and as a binder for ceramic production. Specifically, it can be applied as a part or all of a functional film that can impart various functionalities to a substrate, such as a protective film for machine parts or cutting tools, an insulating film for semiconductors, magnetic substances, solar cells, etc., a dielectric film, an antireflection film, a surface device, a magnetic head, an infrared sensor element, etc., a barrier film against air, moisture, etc. in packaging materials for foods, drugs, medical devices, etc., a coating film for a substrate such as various powders, films, films or molded articles made of glass or plastic, and an aluminum oxide film used for purposes such as a binder for manufacturing heat-resistant materials, high-hardness films, optical elements, and ceramics using these.

[Substrate having an aluminum oxide film and substrate having a functional film containing aluminum oxide]

In addition, the substrate having these aluminum oxide films or functional films containing aluminum oxide can be used as heat-resistant materials such as heat-resistant films, insulating materials, materials such as barrier films against moisture or oxygen, anti-reflection films, anti-reflection materials such as glass, and high-hardness films or materials.

<Third aspect of the present invention>

<Method for manufacturing an article having an aluminum oxide film>

A method for manufacturing an article having an aluminum oxide film of the present invention comprises the following steps (A) and (B).

Process (A) A process of forming a coating film by spraying an organic solvent solution of an organoaluminum compound or a partial hydrolyzate thereof represented by the general formula (6) below onto at least a portion of the surface of a substrate.

(In the formula, R ¹ represents hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, and R ² and R ³ independently represent hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, a straight-chain or branched alkoxyl group having 1 to 7 carbon atoms, an acyloxy group, or an acetylacetonate group.)

(B) A process of heating a substrate having the above coating film formed thereon at a temperature of 400°C or lower under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture, and forming an aluminum oxide film from the coating film.

Process (A)

Process (A) is a process of forming a coating film by spraying an organic solvent solution of an organoaluminum compound represented by general formula (6) onto at least a portion of the surface of a substrate (hereinafter referred to as process (A1)), or a process of forming a coating film by spraying an organic solvent solution of a partial hydrolyzate of an organoaluminum compound represented by general formula (6) onto at least a portion of the surface of a substrate (hereinafter referred to as process (A2)).

The organoaluminum compound represented by the general formula (6) is the same as the organoaluminum compound represented by the general formula (6) in the second aspect of the present invention, and reference is made to the description in the second aspect of the present invention.

In addition, aluminum compounds such as alkyl aluminum such as triisobutyl aluminum, tri-n-butyl aluminum, trihexyl aluminum, and trioctyl aluminum, alkoxides such as aluminum triisopropoxide, aluminum sec-butoxide, and aluminum tert-butoxide, β-diketonate complexes such as aluminum acetylacetonate, and inorganic salts such as aluminum acetate and aluminum hydroxide may be coexisted in the solution used in the present invention, within a range that does not interfere with the invention.

Spray application solution used in process (A1)

The spray application solution used in process (A1) is a solution in which an organoaluminum compound represented by general formula (6) is dissolved in an organic solvent. Since the organoaluminum compound represented by general formula (6) is used in process (A1) without being hydrolyzed, it is appropriate for R ¹ to be a straight-chain or branched alkyl group having 1 to 3 carbon atoms.

From the viewpoint of having solubility for the organoaluminum compound represented by the general formula (6), it is appropriate for the organic solvent to be an electron-donating organic solvent. The organic solvent having electron-donating property may be any solvent that has solubility for the organoaluminum compound represented by the general formula (6).

Examples of electron-donating organic solvents include ether solvents such as 1,2-diethoxyethane, 1,2-dibutoxyethane, diethyl ether, di-n-propyl ether, diisopropyl ether, dibutyl ether, cyclopentyl methyl ether, tetrahydrofuran, dioxane, glyme, diglyme, triglyme, anisole, and methoxytoluene; and amine solvents such as trimethylamine, triethylamine, and triphenylamine. Preferred solvents having electron-donating properties are 1,2-diethoxyethane, tetrahydrofuran, and dioxane.

In process (A1), as a solvent that can coexist with an electron-donating organic solvent, a hydrocarbon compound can be exemplified, and in process (A1), a mixture of an electron-donating organic solvent and a hydrocarbon compound can also be used as an organic solvent. As the hydrocarbon compound, examples thereof include linear or branched hydrocarbon compounds or cyclic hydrocarbon compounds having 5 to 20 carbon atoms, more preferably 6 to 12 carbon atoms, aromatic hydrocarbon compounds having 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms, and mixtures thereof. Specific examples of hydrocarbon compounds include aliphatic hydrocarbons such as pentane, n-hexane, heptane, isohexane, methylpentane, octane, 2,2,4-trimethylpentane (isooctane), n-nonane, n-decane, n-hexadecane, octadecane, eicosane, methylheptane, 2,2-dimethylhexane, and 2-methyloctane; alicyclic hydrocarbons such as cyclopentane, cyclohexanemethylcyclohexane, and ethylcyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, cumene, and trimethylbenzene; and hydrocarbon solvents such as mineral spirits, solvent naphtha, kerosene, and petroleum ether.

In the spray-coating solution used in process (A1), the concentration of the organoaluminum compound represented by the general formula (6) is suitably in the range of 0.1 to 35 mass% from the viewpoint of easy control of the reactivity. The higher the concentration, the fewer the number of coatings a film can be produced, but the reactivity of the organoaluminum compound having an alkyl group having 1 to 3 carbon atoms increases, making handling other than during film formation difficult. Therefore, the upper limit of the concentration is usually a problem, and the concentration of the compound is preferably 0.1 to 25 mass%, more preferably 0.1 to 15 mass%, and even more preferably 0.1 to 12 mass%.

Spray application solution used in process (A2)

The spray-coating solution used in process (A2) is an organic solvent solution of a partial hydrolyzate of an organoaluminum compound represented by general formula (6). The organoaluminum compound represented by general formula (6) is as described above. As the organic solvent, any organic solvent among hydrocarbon compounds, electron-donating organic solvents and mixtures thereof can be used. The hydrocarbon compounds and electron-donating organic solvents are the same as those described in process (A1).

A partial hydrolyzate is a substance obtained by partially hydrolyzing an organoaluminum compound represented by the general formula (6) in an organic solvent using water in a molar ratio of 0.7 or less. If it is a partial hydrolyzate using water in a molar ratio of 0.7 or less, the target aluminum oxide film can be manufactured by spraying the solution for spray application (organoaluminum compound that has not been partially hydrolyzed) used in step (A1) and performing step (B). The partial hydrolysis is performed by adding water to a solution in which the compound represented by the general formula (6) is dissolved in an organic solvent, or by mixing the organic solvent solution of the compound represented by the general formula (6) and water. The amount of water added is preferably in a range of 0.6 or less in terms of the molar ratio with respect to the organoaluminum compound, because spray application is possible in the same manner as the solution for spray application (organoaluminum compound that has not been partially hydrolyzed) used in step (A1). There is no lower limit to the amount of water to be added, but since the process of partial hydrolysis is imparted, the addition of a small amount of water only makes the operation complicated, so it can be, for example, 0.05 or more, preferably 0.1 or more.

The concentration of the compound represented by the general formula (6) in the above solution is appropriately determined by considering the solubility in an organic solvent and the concentration of the partial hydrolyzate in the obtained partial hydrolyzate, but is suitably set to a range of 0.1 to 50 mass%, and is preferably set to a range of 0.1 to 35 mass%.

The addition or mixing of water may be carried out without mixing the water with another solvent, or may be carried out after mixing the water with another solvent. The addition or mixing of water may be carried out for, for example, 60 seconds to 10 hours, depending on the scale of the reaction. From the viewpoint of a good yield of the partial hydrolyzate, it is preferable to add water by dropping it into the organoaluminum compound of the general formula (6), which is the raw material. The addition of water may be carried out, for example, without stirring (in a stationary state) or with stirring) a solution of the compound represented by the general formula (6) and an organic solvent, for example, an electron-donating organic solvent. The temperature at the time of addition may be any temperature selected from -90 to 150°C. From the viewpoint of the reactivity of water and the organoaluminum compound, a temperature of -15 to 30°C is preferable.

After the addition of water, in order to further progress the hydrolysis reaction between the water and the compound represented by the general formula (6), the reaction may be left without stirring (in a still state) for, for example, 1 minute to 48 hours, or may be stirred. As for the reaction temperature, the reaction may be carried out at any temperature between -90 and 150°C. A temperature of -15 to 80°C is preferable from the viewpoint of obtaining a partially hydrolyzed product in a high yield. The pressure in the hydrolysis reaction is not limited. Usually, it can be carried out at normal pressure (atmospheric pressure).

The progress of the hydrolysis reaction between water and the compound represented by the general formula (6) can be monitored, as needed, by sampling the reaction mixture and analyzing the sample using NMR or IR, or by sampling the gas generated.

The organic solvent, the organic aluminum compound of the general formula (6) as a raw material, and water can be introduced into the reaction vessel by any conventional method, and the organic aluminum compound and water can also be introduced as a mixture with the organic solvent, respectively. The hydrolysis reaction process may be any of a batch operation type, a semi-batch operation type, and a continuous operation type, and there is no particular limitation, but a batch operation type is preferred.

By the above hydrolysis reaction, the organoaluminum compound of the general formula (6) can be partially hydrolyzed by water, thereby obtaining a product including a partial hydrolyzate. When the organoaluminum compound of the general formula (6) is trimethylaluminum or triethylaluminum, analysis on the hydrolyzate has been performed for a long time. However, the results differ depending on the report, and the composition of the product is not clearly specified. In addition, the composition of the product can change depending on the molar ratio of water added, the reaction time, etc. The main component of the product in the method of the present invention is a partial hydrolyzate, and the partial hydrolyzate is presumed to be a mixture of compounds including a structural unit represented by the following general formula (7), as in the second aspect of the present invention:

(In the formula, Q is the same as any one of R ¹ , R ² , and R ³ in general formula (6), and m is an integer from 1 to 200.)

After completion of the hydrolysis reaction, part or all of the product can be recovered and/or purified by a general method such as filtration, concentration, extraction, or column chromatography. In conditions where the molar ratio of water to the organoaluminum compound of the general formula (6) is relatively high, insoluble matters may be generated, and in this case, it is preferable to filter using a filter having a pore diameter of, for example, 3 µm or less, to obtain a composition containing a partial hydrolyzate that is substantially free of insoluble matters.

The partial hydrolysate (solid content) recovered by separation from the organic solvent by the above method can be dissolved in an organic solvent for spray application that is different from the organic solvent used in the reaction to prepare a composition for spray application. However, the partial hydrolysate content, which is a reaction product mixture, can be prepared as is or by adjusting the concentration appropriately to prepare a solution for spray application without separation from the organic solvent.

Examples of organic solvents that can be used as organic solvents for spray application include straight-chain, branched hydrocarbon compounds or cyclic hydrocarbon compounds having 5 to 20 carbon atoms, more preferably 6 to 12 carbon atoms, aromatic hydrocarbon compounds having 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms, and mixtures thereof.

Specific examples of these hydrocarbon compounds include aliphatic hydrocarbons such as pentane, n-hexane, heptane, isohexane, methylpentane, octane, 2,2,4-trimethylpentane (isooctane), n-nonane, n-decane, n-hexadecane, octadecane, eicosane, methylheptane, 2,2-dimethylhexane, and 2-methyloctane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, and ethyl cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, cumene, and trimethylbenzene; and hydrocarbon solvents such as mineral spirits, solvent naphtha, kerosene, and petroleum ether.

Other examples of organic solvents that can be used as organic solvents for spray application include ether solvents such as 1,2-diethoxyethane, 1,2-dibutoxyethane, diethyl ether, di-n-propyl ether, diisopropyl ether, dibutyl ether, cyclopentyl methyl ether, tetrahydrofuran, dioxane, glyme, diglyme, triglyme, anisole, and methoxytoluene; and amine solvents such as trimethylamine, triethylamine, and triphenylamine.

In addition, these organic solvents can be used alone or in combination of two or more types.

In addition, in the spray application solution, when R ¹ , R ² , and R ³ remaining in the solution after hydrolysis are alkoxide groups, alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, isobutyl alcohol, n-butyl alcohol, and diethylene glycol, which can coexist in the composition, can also be used as organic solvents for spray application.

The solid content concentration of the partial hydrolyzate of the composition containing the partial hydrolyzate used in process (A2) may be, for example, in the range of 0.1 to 30 mass%. The higher the concentration, the fewer the number of coatings a film can be produced, but considering the solubility of the reaction product containing the partial hydrolyzate of the organoaluminum compound, for example, the ease of forming an aluminum oxide film, the solid content concentration may preferably be 0.1 to 25 mass%, more preferably 0.1 to 15 mass%.

The spray-coating solution containing a partial hydrolyzate used in the above process (A2) corresponds to the composition for forming an aluminum oxide film of the present invention.

<About spray application>

Spray application is common to both process (A1) and process (A2).

Spray application is performed by spraying a solution for spray application onto at least a portion of the surface of a substrate. By spraying, a film of the solution for spray application is formed. Spray application can be performed at room temperature, but can also be performed under heating, as described below. In addition, spray application is performed under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture.

The reason why spray application is performed under an inert gas atmosphere is that the organoaluminum compound and/or the partial hydrolyzate included in the spray application solution reacts with moisture in the atmosphere and gradually decomposes, or it is easy to control the film formation under conditions in which water coexists with the spray application solution in order to form an aluminum oxide film, or it is possible to handle flammable solvents, etc. There is no particular limitation on the inert gas, but examples thereof include helium, argon, and nitrogen. Among these, nitrogen is particularly preferable in terms of cost. In addition, with respect to the pressure at the time of application, it can be performed under any of atmospheric pressure, pressurized pressure, and reduced pressure, but it is usually preferable to perform the application under atmospheric pressure because it is simple in terms of equipment and does not incur costs.

In addition, an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture is used for the inert gas atmosphere. For spray application, a spray application method in which aluminum oxide is easily formed by a reaction with an oxygen source such as water existing in the space until the spray application solution reaches the substrate by spraying, such as a spray application method, a spray pyrolysis method, an electrostatic application method, or an inkjet method, is used. At that time, since the inert gas atmosphere contains 0.5 mol% to 30 mol% of moisture, a hydrolysis reaction progresses in the space until the spray reaches the substrate, and the subsequent formation of an aluminum oxide thin film becomes smooth. From the viewpoint of making the formation of the aluminum oxide thin film smoother, the moisture content of the inert gas atmosphere is preferably 1 mol% to 25 mol%. As examples of the inert gas containing this specific moisture, for example, an inert gas containing 0.5 mol% of moisture, a dew point of -2°C and a relative humidity of 21% at 21°C can be exemplified, an inert gas containing 1 mol% of moisture, a dew point of 8°C and a relative humidity of 43% at 21°C can be exemplified, and further, an inert gas containing 25 mol% of moisture can be exemplified as one containing saturated water vapor at 65°C.

There is no particular limitation on the inert gas, but examples thereof include helium, argon, and nitrogen. Among these, nitrogen is particularly preferable in terms of cost. Spraying onto the substrate surface can be performed under either pressurized or reduced pressure, but it is preferable to perform it under atmospheric pressure because it is simpler in terms of equipment.

As a spray coating method, for example, spray coating, spray pyrolysis, electrostatic coating, inkjet coating, etc. can be used. Spray pyrolysis and electrostatic coating are methods that can perform coating and film formation simultaneously while heating the substrate, and therefore, the solvent can be dried in parallel with the coating, and depending on the conditions, heating for solvent drying may be unnecessary. Furthermore, depending on the conditions, in addition to drying, at least part of the reaction of the partial hydrolyzate of the organoaluminum compound with aluminum oxide may also proceed. Therefore, in some cases, the formation of an aluminum oxide film by heating at a predetermined temperature, which is a post-process, can be performed more easily.

Process (B)

In process (B), the substrate on which the coating film has been formed is heated at a temperature of 400°C or lower in an inert gas atmosphere containing 0.5 to 30 mol% of moisture, thereby forming an aluminum oxide film from the coating film. The inert gas atmosphere containing 0.5 to 30 mol% of moisture is the same as that described in process (A).

The heating temperature can be appropriately selected depending on the composition of the coating solution, the spray application method, and the type of the substrate. However, it is performed at a temperature of 400°C or lower. Depending on the type of the substrate, it is also possible to form an aluminum oxide film by heating at a temperature exceeding 400°C, but in the present invention, an aluminum oxide film having sufficiently good physical properties can be formed by heating at a temperature of 4400°C or lower.

In addition, depending on the type of spray coating method, the atmosphere and/or the substrate may be heated even during the coating process (A). In this case, it is preferable that the temperatures of coating and heating be the same because the operation is easier. The temperature of the atmosphere and/or the heating of the substrate during coating and film formation in spray coating may be, for example, in the range of 50 to 400°C, preferably 100 to 400°C. In particular, in the present invention, film formation is possible when a substrate having low heat resistance such as a resin is used, or when there is a problem in the treatment of providing heat or high energy to a functional material such as an electronic device film such as an electrode, a semiconductor, an insulator, etc. formed from an inorganic substance such as a metal, oxide, nitride, or carbon compound, or an organic substance such as a low molecule or polymer, and a composite of the above-mentioned inorganic and organic substances, and the temperature is preferably in the range of 50 to 350°C, and more preferably in the range of 100 to 300°C.

In Fig. 3a, as an example of a film-forming device by spray coating used in the present invention, a spray film-forming device is shown. In the drawing, (1) represents a spray bottle filled with a coating liquid, (2) represents a substrate holder, (3) represents a spray nozzle, (4) represents a compressor, (5) represents a substrate, and (6) represents a tube for introducing water vapor. In spray coating, a substrate is installed in a substrate holder (2), and, if necessary, a heater is used to heat the substrate to a predetermined temperature, and then, in an inert gas atmosphere (under atmospheric pressure), compressed inert gas and the coating liquid are simultaneously supplied from a spray nozzle (3) arranged above the substrate, so as to atomize and spray the coating liquid, and water is introduced from a tube for introducing water vapor (6) so as to coexist in the film-forming atmosphere, whereby an aluminum oxide film thin film can be formed on the substrate. When spray coating is performed under heating, an aluminum oxide film can also be formed without additional heating, etc.

Considering the adhesion to the substrate, the ease of evaporation of the solvent, etc., it is preferable that the spray application of the coating solution be ejected from the spray nozzle so that the droplet size is within a range of 30 ㎛. In addition, considering that the organic solvent evaporates to some extent before reaching the substrate, thereby reducing the size of the droplet, it is preferable that the spray nozzle be performed at a distance of 50 cm or less from the viewpoint of being able to produce an aluminum oxide film.

The film formation method by spray coating such as spray pyrolysis or electrostatic coating is a method that can perform coating and film formation simultaneously while heating the substrate, and therefore the organic solvent can be dried in parallel with the coating, and depending on the conditions, there are cases where heating for solvent drying is unnecessary. Furthermore, depending on the conditions, in addition to drying, the reaction of the partial hydrolyzate of the organic aluminum compound with aluminum oxide may also proceed at least partially. Therefore, there are cases where the formation of an aluminum oxide film by heating at a predetermined temperature, which is a post-process, can be performed more easily. The heating temperature of the substrate at the time of coating and film formation in the spray pyrolysis method can be, for example, in the range of 50 to 400°C, preferably 100 to 400°C. In particular, when a substrate having low heat resistance such as a resin is used as the substrate, it can be performed in the range of 50 to 350°C, preferably 50 to 350°C.

In addition, in process (A), after spraying the solution for spray application onto the surface of the substrate, if necessary, the substrate is dried at a predetermined temperature, and then, in process (B), the aluminum oxide film can be formed by heating the substrate at a predetermined temperature.

The drying temperature of the organic solvent in process (A) can be, for example, in the range of 20 to 200°C, and can be appropriately set depending on the type of coexisting organic solvent. The heating temperature for forming an aluminum oxide film after drying the solvent is as described above.

In the film formation by spray application of the present invention, it is possible to perform solvent drying and aluminum oxide film formation simultaneously by making the solvent drying temperature and the subsequent heating temperature for aluminum oxide film formation the same, and the temperature at that time is set to the heating temperature within the above-mentioned range in step (B).

Meanwhile, spraying and heating in the present invention can be performed under either pressurized or reduced pressure, but it is preferable to perform them at atmospheric pressure because it is simpler in terms of equipment and does not incur costs.

As a substrate for forming an aluminum oxide film in the above manufacturing method, there are inorganic materials such as glass, metal, and ceramics, polymeric substrates such as plastic, organic materials such as paper and wood, and composites thereof.

Specific examples of these descriptions are the same as those described in the second aspect of the present invention.

When the solution for producing an aluminum oxide film of the present invention is used to form a film by spray coating, even at a low film forming temperature, an aluminum oxide film having excellent adhesion to a substrate and a good oxide formation state can be formed by only performing coating and heating. The aluminum oxide film itself obtained using the solution for producing an aluminum oxide of the present invention has high adhesion to a substrate, and good adhesion is obtained even on a substrate on which direct oxide film formation is usually difficult. However, if necessary, it is also possible to form a film by coating using a method for increasing the adhesion of oxide formed on a substrate, such as undercoat treatment, primer treatment, corona treatment, UV irradiation, or chlorination.

[Aluminum oxide and aluminum oxide film]

When film formation is performed by spray coating using the solution for producing an aluminum oxide film of the present invention, an aluminum oxide film having excellent adhesion to a substrate and a good oxide formation state can be formed simply by performing coating and heating, even at a low film formation temperature.

The manufactured aluminum oxide film, "aluminum oxide" in the present invention refers to a compound containing aluminum element and oxygen element, and the proportion of these two elements in the aluminum oxide is 90% or more. In addition to aluminum and oxygen, it may contain hydrogen or carbon. In addition, the "aluminum oxide film" manufactured at 500°C or lower in the present invention usually does not have a clear peak observed in X-ray diffraction analysis, and is in an amorphous state.

These aluminum oxide films can also be crystallized by a generally known method, such as heating at a high temperature of 1000°C or higher, as a post-treatment after film formation, if the heat-resistant temperature of the substrate, etc. allows. That is, if necessary, after the aluminum oxide film is formed in step (B), the heating can be further performed in an oxidizing gas atmosphere such as oxygen, or in a plasma atmosphere such as argon or oxygen, thereby promoting the formation of aluminum oxide or improving crystallinity. In addition, in order to remove carbon components such as residual organic substances in the aluminum oxide film obtained in the present invention, or to improve the film quality of the aluminum oxide film, treatment using light irradiation such as ultraviolet rays or microwaves, which are generally used, may be performed. The film thickness of the aluminum oxide film is not particularly limited, but may be, for example, in the range of 0.005 to 5 μm, and more practically, in the range of 0.001 to 5 μm. According to the manufacturing method of the present invention, a film having a film thickness in the above range can be appropriately manufactured by repeating the coating (drying) heating once or more. Also, in principle, it is also possible to form a film of 5 μm or more by repeating the number of coatings or extending the coating time. The manufacturing method of the present invention includes performing the step (A) of applying the spray coating solution to the surface of a substrate under an inert gas atmosphere and the step (B) of heating the obtained coating once or twice or more. The operations of applying and heating the obtained coating can be performed as many times as necessary to obtain desired properties such as insulation or heat resistance, but can be performed appropriately in a range such as preferably 1 to 50 times, more preferably 1 to 30 times, and even more preferably 1 to 10 times. In the spray coating method used in the present invention, a film having a high transmittance, from transparent to translucent and opaque, can be obtained. A film having high adhesion to a substrate such as glass or resin can be obtained.

[Functional film containing aluminum oxide]

The manufactured aluminum oxide film has excellent adhesion to a substrate, and the oxide formation state is good. Therefore, a composite (article) in which an aluminum oxide film is attached to a substrate, or a composite film having layers other than an aluminum oxide film and an aluminum oxide film can be attached to a substrate. The composite film can be used as a functional film containing aluminum oxide. For example, it can be provided for uses such as production of an alumina sheet for electronic materials, an aluminum oxide film, production of a catalyst carrier, imparting heat resistance, imparting barrier properties against air and moisture, imparting an antireflection effect, imparting an antistatic effect, imparting an antifogging effect, imparting wear resistance, etc., and as a binder for ceramic manufacturing. Specifically, it can be applied as a part or all of a functional film that can impart various functionalities to a substrate, such as a protective film for machine parts or cutting tools, an insulating film for semiconductors, magnetic substances, solar cells, etc., a dielectric film, an antireflection film, a surface device, a magnetic head, an infrared sensor element, etc., a barrier film against air, moisture, etc. in packaging materials for foods, drugs, medical devices, etc., a coating film for a substrate such as various powders, films, films or molded articles made of glass or plastic, and an aluminum oxide film used for purposes such as a binder for manufacturing heat-resistant materials, high-hardness films, optical elements, and ceramics using these.

[Substrate having an aluminum oxide film and substrate having a functional film containing aluminum oxide]

In addition, the substrate having the aluminum oxide film or the functional film containing the aluminum oxide can be used as a heat-resistant material such as a heat-resistant film, an insulating material, a material such as a barrier film against moisture or oxygen, an anti-reflection film, an anti-reflection material such as glass, and a high-hardness film or material.

[Composition for manufacturing aluminum oxide film]

The present invention includes a composition for forming an aluminum oxide film.

The first aspect of the composition is a film-forming composition comprising an organic solvent solution of an organoaluminum compound represented by the general formula (6), wherein the composition is for use in forming an aluminum oxide film, in which the coating formation of the film is performed under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture.

The second aspect of the composition is a film-forming composition containing a partial hydrolyzate of the organoaluminum compound represented by the general formula (6) obtained by partially hydrolyzing the organoaluminum compound in an organic solvent,

(a) The partial hydrolysis is carried out using water having a molar ratio of 0.7 or less to the organoaluminum compound, and

(b) The composition is for use in the formation of an aluminum oxide film, in which film coating is performed under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture.

The composition of the first aspect is described as a solution for spray application in process (A1). The composition of the second aspect is described as a solution for spray application in process (A2).

The film coating formation performed under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture is

(c1) a process of forming a coating film by spraying the composition onto at least a portion of the surface of a substrate under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture, and

(c2) A process of forming an aluminum oxide film by heating the substrate having the above coating film formed thereon at a temperature of 400° C. or lower under an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture. These processes are as described above as process (A) and process (B).

The composition of the present invention is a composition used to form a transparent aluminum oxide film adhered to a substrate.

<Fourth aspect of the present invention>

[Solution containing alkyl aluminum]

The first aspect of the fourth aspect of the present invention is a method for producing an aluminum oxide thin film, characterized in that a solution containing an alkyl aluminum compound, which comprises dialkyl aluminum, trialkyl aluminum or a mixture thereof (provided that the alkyl groups of the dialkyl aluminum and trialkyl aluminum have 1 to 6 carbon atoms and may be the same or different), and an organic solvent having electron donating properties and not containing active hydrogen atoms, is applied to a substrate in the form of droplets having an average particle diameter of 3 to 30 μm in the air to form a coating film, and the formed coating film is heated after drying the organic solvent, or in parallel with drying the organic solvent, to form aluminum oxide.

The alkyl aluminum compound-containing solution of the present invention can chemically stabilize an alkyl aluminum compound, which is dialkyl aluminum, trialkyl aluminum or a mixture thereof, by containing an organic solvent that has electron donating properties and does not contain active hydrogen atoms as an organic solvent. The reason why an organic solvent that has electron donating properties and does not contain active hydrogen atoms is preferred is not clear, but it is presumed that the reactivity toward water is appropriately enhanced by coordination bonding of the unshared electron pair of oxygen in the structure to aluminum.

Regarding the ratio of the alkyl aluminum compound and the organic solvent having electron donating property and not containing active hydrogen atoms in the solution of the present invention, from the viewpoint of keeping the alkyl aluminum compound chemically stable, it is preferable to contain an organic solvent having electron donating property and not containing active hydrogen atoms in a molar ratio of 1 or more with respect to the alkyl aluminum compound. By containing an organic solvent having electron donating property and not containing active hydrogen atoms in a molar ratio of 1 or more with respect to the alkyl aluminum compound, chemical changes such as spontaneous ignition of the solution can be suppressed, and the reactivity toward water can be made appropriate.

The above active hydrogen atom refers to a highly reactive hydrogen atom bonded to an atom of an element other than a carbon atom, such as a nitrogen atom, an oxygen atom, or a sulfur atom, among the hydrogen atoms in the molecule of an organic compound.

Examples of organic solvents having electron donating properties and not containing active hydrogen atoms include ether compounds such as diethyl ether, tetrahydrofuran, t-butyl methyl ether, di-n-propyl ether, diisopropyl ether, 1,4-dioxane, 1,3-dioxalan, dibutyl ether, cyclopentyl methyl ether, and anisole; ethylene glycol dialkyl ether compounds such as 1,2-dimethoxyethane, 1,2-diethoxyethane, and 1,2-dibutoxyethane; diethylene glycol dialkyl ether compounds such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol dibutyl ether; triethylene glycol dialkyl ether compounds such as triethylene glycol dimethyl ether and triethylene glycol diethyl ether; Propylene glycol dialkyl compounds such as propylene glycol dimethyl ether; dipropylene glycol dialkyl compounds such as dipropylene glycol dimethyl; tripropylene glycol dialkyl compounds such as tripropylene glycol dimethyl; ester compounds such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, pentyl acetate, methoxybutyl acetate, amyl acetate, and cellosolve acetate; amide compounds such as N,N-dimethylformamide; cyclic amide compounds such as N-methyl-2-pyrrolidone, 1,3-dimethyl-imidazolidinone, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone; Examples of carbonate compounds include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and the like, or mixtures thereof.

Alcohol solvents such as ethanol, isopropanol, and butanol, and carboxylic acid solvents such as formic acid, acetic acid, and propionic acid all have active hydrogen atoms, and therefore are not organic solvents that have the electron-donating property and do not contain active hydrogen atoms.

Conjugated diketones such as acetylacetone are not organic solvents that have the electron-donating property and do not contain active hydrogen atoms because they become enolate compounds and generate active hydrogen atoms.

The above dialkyl aluminum and/or trialkyl aluminum has an alkyl group having 1 to 6 carbon atoms, and the multiple alkyl groups of one dialkyl aluminum or one trialkyl aluminum may be the same or different.

The above dialkylaluminum refers to a trivalent aluminum compound in which two ligands are alkyl groups and one ligand is not an alkyl group, and the above trialkylaluminum refers to a trivalent aluminum compound in which all three ligands are alkyl groups.

The dialkylaluminum and/or trialkylaluminum may be, for example, an alkylaluminum compound represented by the following general formula (8) or (9):

(In the formula, R ¹ represents a methyl group or an ethyl group.)

(In the formula, R ² represents an isobutyl group, and R ³ represents hydrogen or an isobutyl group.)

Examples of compounds represented by general formula (8) include trimethylaluminum, triethylaluminum, etc.

Examples of compounds represented by general formula (9) include triisobutylaluminum, diisobutylaluminum hydride, etc.

The above dialkyl aluminum and/or trialkyl aluminum is preferably triethyl aluminum or triisobutyl aluminum from the viewpoint of low price per unit mass of aluminum.

The concentration of the alkyl aluminum compound in the alkyl aluminum containing solution used in the manufacturing method of the present invention may be, for example, 1 mass% or more and 20 mass% or less. In the case of the alkyl aluminum compound represented by the general formula (8), it is preferably 1 mass% or more and 10 mass% or less, and in the case of the alkyl aluminum compound represented by the general formula (9), it is preferably 1 mass% or more and 20 mass% or less. If it is less than 1 mass%, the productivity of the film decreases, so it is preferably 1 mass% or more. The concentration of the alkyl aluminum compound in the alkyl aluminum containing solution affects the risk of ignition, etc., especially when manufacturing aluminum oxide by applying in the air, but by setting it within the above concentration range, there is an advantage in that an aluminum oxide thin film can be safely manufactured without having to pay special attention.

The alkyl aluminum-containing solution used in the manufacturing method of the present invention may further include an organic solvent other than an organic solvent having electron donating property and not containing active hydrogen atoms, which is not an organic solvent having electron donating property and not containing active hydrogen atoms. By adding an organic solvent having neither electron donating property nor containing active hydrogen atoms, the polarity, viscosity, boiling point, economy, etc. can be adjusted. Examples of the organic solvent having neither electron donating property nor containing active hydrogen atoms include aliphatic hydrocarbons such as n-hexane, octane, and n-decane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, and cumene; and hydrocarbon solvents such as mineral spirits, solvent naphtha, kerosene, and petroleum ether. The amount of the organic solvent which does not have electron-donating property and does not contain active hydrogen atoms to be added is not limited as long as it does not interfere with the effect of the organic solvent which has electron-donating property and does not contain active hydrogen atoms, and for example, it can be 100 parts by mass or less with respect to 100 parts by mass of the organic solvent which has electron-donating property and does not contain active hydrogen atoms. However, the range which can be added varies depending on the type of the alkyl aluminum compound, the organic solvent which has electron-donating property and does not contain active hydrogen atoms, and the type of the organic solvent which does not have electron-donating property and does not contain active hydrogen atoms. In addition, in the solution containing the alkyl aluminum compound, if the organic solvent which has electron-donating property and does not contain active hydrogen atoms is contained at a molar ratio of 1 or more with respect to the alkyl aluminum compound, the alkyl aluminum compound in the solution containing the alkyl aluminum compound can be chemically stabilized. Therefore, when using an organic solvent which does not have electron-donating property and does not contain active hydrogen atoms together, it is preferable to determine the combined amount by taking this point into consideration.

The above-mentioned organic solvent having electron-donating properties and not containing active hydrogen atoms, and optionally, the mixing of the organic solvent having electron-donating properties and not containing active hydrogen atoms with the alkyl aluminum compound can be carried out in a reaction vessel under an inert gas atmosphere, and each can be introduced according to any conventional method. The alkyl aluminum compound can also be introduced into the reaction vessel as a mixture with the organic solvent having electron-donating properties and not containing active hydrogen atoms.

The order of introduction into the mixing vessel may be any of the following: the alkyl aluminum compound, the organic solvent having electron donating properties and not containing active hydrogen atoms, and optionally the organic compound having no electron donating properties and not containing active hydrogen atoms, or the organic solvent having electron donating properties and not containing active hydrogen atoms, and optionally the organic solvent having no electron donating properties and not containing active hydrogen atoms, and the alkyl aluminum, or all of them may be introduced simultaneously.

The introduction time into the mixing vessel can be appropriately set according to the type and capacity of the raw material to be mixed, but can be performed for, for example, between 1 minute and 10 hours. The temperature at the time of introduction can be selected from any temperature between -15 and 150°C. However, considering safety such as excluding the risk of ignition at the time of introduction, it is preferable that the temperature be in the range of -15 to 80°C.

When introducing raw materials into a mixing vessel, the stirring process after introduction may be any of batch operation, semi-batch operation, or continuous operation.

[Method for producing aluminum oxide thin film]

The method for producing an aluminum oxide thin film of the present invention comprises applying a solution containing the alkyl aluminum compound to a substrate to form a coating film, and heating the formed coating film to form aluminum oxide after drying an organic solvent, or in parallel with drying the organic solvent, thereby obtaining an aluminum oxide thin film.

The application of the solution containing the alkyl aluminum compound to the above-mentioned description is preferably performed by a method such as a spray application method, an electrostatic spray application method, an inkjet method, or a mist CVD method, and the spray application method is more preferable because the apparatus is simpler.

The application of the solution containing the alkyl aluminum compound for the above-mentioned description is performed in an air atmosphere from the viewpoint of economy. By performing the application in an air atmosphere, the device becomes simpler, which is preferable.

The application of the solution containing the alkyl aluminum compound for the above-mentioned description can be carried out under either pressurized or reduced pressure, but from the standpoint of economy, it is preferable to carry out the application under atmospheric pressure because the apparatus is also simpler.

The application of the solution containing an alkyl aluminum compound to the above-described substrate is carried out by applying the solution containing an alkyl aluminum compound to the substrate in the form of droplets having an average particle size of 1 to 100 μm. If droplets having an average particle size of less than 1 μm of the solution containing an alkyl aluminum compound are used, the material usage efficiency (attachment efficiency to the substrate) decreases, and if droplets having an average particle size of more than 100 μm are used, the properties of the film formed by the application (particularly density) decrease, and therefore the average particle size of the solution containing an alkyl aluminum compound is limited to the above-described range. It is preferable to apply the solution containing an alkyl aluminum compound to the substrate in the form of droplets having an average particle size of 3 to 30 μm from the viewpoints that the material usage efficiency (attachment efficiency to the substrate) is high and the properties of the film formed by the application (particularly density) are good. For example, the solution containing an alkyl aluminum compound can be made into droplets having a particle size of 1 to 100 μm by passing the solution through a precision spray nozzle. It is preferable that the spray nozzle is a two-fluid nozzle, and the droplets are preferably 3 to 30 ㎛. When the droplets are 3 ㎛ or more, the attachment efficiency of the droplets to the substrate is improved, and when the droplets are 30 ㎛ or less, the film properties (transparency, uniformity within the surface, density) are improved.

When applying, it is preferable to carry out the application with the distance between the spray nozzle and the substrate within 50 cm, and more preferably within 20 cm. If it is more than 50 cm, the solvent in the droplet dries before reaching the substrate, reducing the size of the droplet and reducing the attachment efficiency of the droplet to the substrate.

It is desirable that the ambient temperature when applying be below 50℃.

The humidity of the air may be, for example, an air atmosphere containing water at a relative humidity of 20 to 90% converted to 25°C. The relative humidity converted to 25°C is more preferably 30 to 70% from the viewpoint of smooth formation of an aluminum oxide film.

The above-mentioned description is not particularly limited as long as it is a description of a substrate on which it is desired to form an aluminum oxide thin film. Specific examples of the above-mentioned description are the same as those described in the first aspect of the present invention.

The shape of the above description may include a powder, a film, a plate, or a three-dimensional structure having a three-dimensional shape, but is not intended to be limited thereto.

The above-mentioned alkyl aluminum compound containing solution is applied to form a coating film, and then the formed coating film is fired by drying the organic solvent while the substrate is at a predetermined temperature, or by heating at a predetermined temperature simultaneously with the drying, to form an aluminum oxide thin film. The film thickness of the coating film formed by applying the alkyl aluminum compound containing solution can be appropriately determined in consideration of the desired film of the aluminum oxide thin film. Meanwhile, the substrate can be heated to a predetermined temperature before the coating, or the solvent can be dried simultaneously with the coating by applying to a substrate heated to a predetermined temperature, or the coating can be fired simultaneously with the drying. The above-mentioned predetermined temperature is, for example, 300°C or lower. If the heating is at a temperature of 300°C or lower, the coating can be applied even to a substrate that does not have heat resistance, such as plastic.

The temperature for drying the solvent may be any temperature selected from, for example, 20 to 250° C. The solvent may be dried for, for example, 0.5 to 60 minutes. However, the present invention is not intended to be limited to these ranges.

The predetermined temperature for sintering to form the above aluminum oxide can be selected from any temperature between 50 and 600°C, for example. However, considering the type of the substrate, it is appropriate to set it to a temperature at which the substrate is not damaged. From the viewpoint of being applicable to substrates without heat resistance such as plastics, it is preferable that it is 300°C or lower. When the predetermined temperature for sintering is the same as the predetermined temperature for drying the solvent, the drying of the solvent and the sintering can be performed simultaneously. The solvent-dried precursor film can be sintered for, for example, 0.5 to 300 minutes.

The film thickness of the aluminum oxide thin film obtained as described above may be, for example, in the range of 0.005 ㎛ to 3 ㎛. However, it is not intended to be limited to this range, and the film thickness may be appropriately determined depending on the intention of forming the aluminum oxide thin film.

If necessary, the aluminum oxide film obtained as described above can be heated at a predetermined temperature in an oxidizing gas atmosphere such as oxygen, a reducing gas atmosphere such as hydrogen, a water vapor atmosphere containing a large amount of moisture, or a plasma atmosphere such as argon, nitrogen, or oxygen, thereby improving the crystallinity and density of the aluminum oxide film. Residual organic substances, etc. in the obtained aluminum oxide film can be removed by light irradiation such as ultraviolet rays or microwave treatment.

According to the manufacturing method of the present invention, a substrate having an aluminum oxide thin film attached thereto, which has an aluminum oxide thin film having a vertical transmittance of 80% or more at 550 nm of visible light, can be obtained. The higher the vertical transmittance of the aluminum oxide thin film at 550 nm of visible light, the higher the transparency in the visible light range, which is preferable. For example, it is more preferable that it is 90% or more, and it is still more preferable that it is 95% or more.

<Fifth aspect of the present invention>

[Film forming agent]

The present invention relates to a passive film forming agent. The passive film means "a film formed on at least a part of the back surface of a silicon substrate and suppressing back surface recombination of carriers in the silicon substrate." There is no particular limitation on the silicon substrate on which the passive film is formed. However, from the viewpoint of the high necessity of suppressing back surface recombination of carriers in the silicon substrate, it may be a silicon substrate such as crystalline silicon.

The passive film forming agent of the present invention comprises an alkyl aluminum compound composed of dialkyl aluminum, trialkyl aluminum or a mixture thereof (provided that the alkyl groups of the dialkyl aluminum and trialkyl aluminum have 1 to 6 carbon atoms and may be the same or different), and a solution containing the alkyl aluminum compound, which contains an organic solvent having electron donating properties and not containing active hydrogen atoms.

The alkyl aluminum compound-containing solution of the present invention can chemically stabilize an alkyl aluminum compound, which is dialkyl aluminum, trialkyl aluminum or a mixture thereof, by containing an organic solvent that has electron donating properties and does not contain active hydrogen atoms as an organic solvent. The reason why an organic solvent that has electron donating properties and does not contain active hydrogen atoms is preferred is not clear, but it is presumed that the reactivity toward water is appropriately enhanced by coordination bonding of the unshared electron pair of oxygen in the structure to aluminum.

Regarding the ratio of the alkyl aluminum compound and the organic solvent having electron donating property and not containing active hydrogen atoms in the solution of the present invention, from the viewpoint of keeping the alkyl aluminum compound chemically stable, it is preferable to contain an organic compound having electron donating property of 1 or more and not containing active hydrogen atoms in a molar ratio with respect to the alkyl aluminum compound. By containing an organic solvent having electron donating property of 1 or more and not containing active hydrogen atoms in a molar ratio with respect to the alkyl aluminum compound, it is possible to suppress chemical changes such as spontaneous ignition of the solution and to make the reactivity toward water appropriate.

The above active hydrogen atom refers to a highly reactive hydrogen atom bonded to an atom of an element other than a carbon atom, such as a nitrogen atom, an oxygen atom, or a sulfur atom, among the hydrogen atoms in the molecule of an organic compound.

An example of an organic solvent having electron donating properties and not containing active hydrogen atoms is the same as the organic solvent having electron donating properties and not containing active hydrogen atoms in the fourth aspect of the present invention.

Alcohol solvents such as ethanol, isopropanol, and butanol, and carboxylic acid solvents such as formic acid, acetic acid, and propionic acid all have active hydrogen atoms, and therefore are not organic solvents that have the electron-donating property and do not contain active hydrogen atoms.

Conjugated diketones such as acetylacetone are not organic solvents that have the electron-donating property and do not contain active hydrogen atoms because they become enolate compounds and generate active hydrogen atoms.

The above dialkyl aluminum and/or trialkyl aluminum has an alkyl group having 1 to 6 carbon atoms, and the multiple alkyl groups possessed by one dialkyl aluminum or one trialkyl aluminum may be the same or different.

The above dialkylaluminum refers to a trivalent aluminum compound in which two ligands are alkyl groups and one is not an alkyl group, and the above trialkylaluminum refers to a trivalent aluminum compound in which all three ligands are alkyl groups.

The dialkylaluminum and/or trialkylaluminum may be, for example, an alkylaluminum compound represented by the general formula (8) or (9), and reference may be made to the description in the fourth aspect of the present invention.

The above dialkyl aluminum and/or trialkyl aluminum is preferably triethyl aluminum or triisobutyl aluminum from the viewpoint of low price per unit mass of aluminum.

The concentration of the alkyl aluminum compound in the alkyl aluminum containing solution of the present invention may be, for example, 1 mass% or more and 20 mass% or less. In the case of the alkyl aluminum compound represented by the general formula (8), it is preferably 1 mass% or more and 10 mass% or less, and in the case of the alkyl aluminum compound represented by the general formula (9), it is preferably 1 mass% or more and 20 mass% or less. If it is less than 1 mass%, the productivity of the passive film decreases, and therefore it is preferably 1 mass% or more. The concentration of the alkyl aluminum compound in the alkyl aluminum containing solution affects the risk of ignition, etc., particularly when producing aluminum oxide by application in the air, but by setting it within the above concentration range, there is an advantage in that a passive film made of aluminum oxide can be safely produced without paying special attention.

The alkyl aluminum-containing solution of the present invention may further include an organic solvent other than an organic solvent having electron donating property and not containing active hydrogen, which is not an organic solvent having electron donating property and not containing active hydrogen atoms. By adding an organic solvent having neither electron donating property nor containing active hydrogen atoms, the polarity, viscosity, boiling point, economy, etc. can be adjusted. Examples of the organic solvent having neither electron donating property nor containing active hydrogen atoms include aliphatic hydrocarbons such as n-hexane, octane, and n-decane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, and cumene; and hydrocarbon solvents such as mineral spirits, solvent naphtha, kerosene, and petroleum ether. The amount of the organic solvent which does not have electron-donating property and does not contain active hydrogen atoms to be added is not limited as long as it does not interfere with the effect of the organic solvent which has electron-donating property and does not contain active hydrogen atoms, and for example, it can be 100 parts by mass or less with respect to 100 parts by mass of the cyclic amide compound. However, the range which can be added varies depending on the type of the alkyl aluminum compound, the organic solvent which has electron-donating property and does not contain active hydrogen atoms, and the type of the organic solvent which does not have electron-donating property and does not contain active hydrogen atoms. On the other hand, in the solution containing the alkyl aluminum compound, if the organic solvent which has electron-donating property and does not contain active hydrogen atoms is contained at a molar ratio of 1 or more with respect to the alkyl aluminum compound, the alkyl aluminum compound in the solution containing the alkyl aluminum compound can be chemically stabilized. Therefore, when using an organic solvent which does not have electron-donating property and does not contain active hydrogen atoms together, it is preferable to determine the combined amount by taking this point into consideration.

The above-mentioned organic solvent having electron donating property and not containing active hydrogen atoms, and optionally, the mixing of the organic solvent having electron donating property and not containing active hydrogen atoms with the alkyl aluminum compound can be carried out in a reaction vessel under an inert gas atmosphere, and each can be introduced according to any conventional method. The alkyl aluminum compound can also be introduced into the reaction vessel as a mixture with the organic solvent having electron donating property and not containing active hydrogen atoms.

The order of introduction into the mixing vessel may be any of the following: the alkyl aluminum compound, the organic solvent having electron-donating properties and not containing active hydrogen atoms, and optionally the organic solvent having no electron-donating properties and not containing active hydrogen atoms, or the organic solvent having electron-donating properties and not containing active hydrogen atoms, and optionally the organic solvent having no electron-donating properties and not containing active hydrogen atoms, and the alkyl aluminum, or all of them may be introduced simultaneously.

The introduction time into the mixing vessel can be appropriately set according to the type and capacity of the raw material to be mixed, but can be performed for, for example, between 1 minute and 10 hours. The temperature at the time of introduction can be selected at any temperature between -15 and 150°C. However, considering safety such as the elimination of the risk of ignition at the time of introduction, the range is preferably between -15 and 80°C.

When introducing raw materials into a mixing vessel, the stirring process after introduction may be any of batch operation, semi-batch operation, or continuous operation.

[Method for manufacturing a silicon substrate having a passive film]

The method for manufacturing a silicon substrate having a passivation film of the present invention is a method for obtaining a silicon substrate having a passivation film made of aluminum oxide, which comprises forming a film by applying a solution containing an alkyl aluminum compound, described as the passivation film forming agent of the present invention, to at least a portion of the back surface of a silicon substrate, and then heating the formed film to form aluminum oxide after drying an organic solvent, or in parallel with drying the organic solvent, thereby forming a passivation film.

The application to the above silicone substrate is preferably carried out by a method such as a spray application method, an electrostatic spray application method, an inkjet method, or a mist CVD method, and the spray application method is more preferable because the device is simpler.

The application of the above-mentioned composition can be carried out either in an inert atmosphere or in an air atmosphere. In the case of an inert atmosphere, it can be carried out using an entire device such as that shown in Fig. 5a.

The application of the above-mentioned composition can be carried out under either pressurized or reduced pressure, but from the standpoint of economy, it is preferable to carry out the application under atmospheric pressure because the apparatus is also simpler.

The coating to the above substrate is performed by coating the alkyl aluminum-containing solution in the form of droplets having an average particle size of 1 to 100 μm on the silicone substrate. If droplets having an average particle size of less than 1 μm of the alkyl aluminum compound-containing solution are used, the material usage efficiency (attachment efficiency to the substrate) decreases, and if droplets having an average particle size of more than 100 μm are used, the properties (particularly density) of the film formed by the coating decrease, and therefore the average particle size of the alkyl aluminum-containing solution is limited to the above range. It is preferable to apply the alkyl aluminum-containing solution to the substrate in the form of droplets having an average particle size of 3 to 30 μm from the viewpoints that the material usage efficiency (attachment efficiency to the substrate) is high and the properties (particularly density) of the film formed by the coating are good. For example, the alkyl aluminum-containing solution can be made into droplets having a particle size of 1 to 100 μm by passing it through a precision-forming spray nozzle. The spray nozzle is preferably a two-fluid nozzle, and the droplets are preferably 3 to 30 ㎛. When the droplets are 3 ㎛ or more, the attachment efficiency of the droplets to the substrate is improved, and when the droplets are 30 ㎛ or less, the film properties (transparency, uniformity within the surface, density) are improved.

When applying, it is preferable to carry out the application with the distance between the spray nozzle and the substrate within 50 cm, and more preferably within 20 cm. If it is more than 50 cm, the solvent in the droplet dries before reaching the substrate, reducing the size of the droplet and reducing the attachment efficiency of the droplet to the substrate.

When applying, it is desirable that the ambient temperature be 50℃ or lower.

When spraying in the air, for example, the air atmosphere may contain water at a relative humidity of 20 to 90% when converted to 25°C. The relative humidity when converted to 25°C is more preferably 30 to 70% from the viewpoint of smooth formation of an aluminum oxide film.

When spraying under an inert atmosphere, moisture is introduced in the form of water vapor or the like from the moisture introduction port (6) of the device of Fig. 5a, thereby making the atmosphere near the substrate into an inert gas atmosphere containing 0.5 mol% to 30 mol% of moisture.

Examples of the above silicon substrate include amorphous silicon, crystalline silicon, single crystal silicon, and polycrystalline silicon.

The shape of the above silicone substrate may be a film, a plate, or a three-dimensional structure having a three-dimensional shape, for example, a spherical shape.

The above silicon substrate is preferably a crystalline silicon substrate from the viewpoint of effective passivation effect.

The above-mentioned alkyl aluminum compound containing solution is applied to form a coating film, and then the formed coating film is fired by drying the organic solvent while the substrate is at a predetermined temperature, or by heating the coating film to a predetermined temperature simultaneously with the drying, to form an aluminum oxide thin film. The film thickness of the coating film formed by applying the alkyl aluminum compound containing solution can be appropriately determined in consideration of the characteristics required as a passive film. Meanwhile, the substrate can be heated to a predetermined temperature before the coating, or the solvent can be dried simultaneously with the coating by applying the coating film to a substrate heated to a predetermined temperature, or the coating film can be fired simultaneously with the drying.

The temperature for drying the solvent may be any temperature selected from, for example, 20 to 250° C. The solvent may be dried for, for example, 0.5 to 60 minutes. However, the present invention is not intended to be limited to these ranges.

The predetermined temperature for sintering to form the above aluminum oxide can be selected at any temperature, for example, from 300 to 600°C. However, considering the type of the substrate, it is appropriate to set it to a temperature at which the substrate is not damaged. When the predetermined temperature for sintering is the same as the predetermined temperature for drying the solvent, the drying of the solvent and the sintering can be performed simultaneously. The solvent-dried precursor film can be sintered for, for example, 0.5 to 300 minutes.

In particular, it is estimated that by setting the sintering temperature to 350 to 500°C, more negative fixed charges can be generated.

The film thickness of the passivation film made of aluminum oxide obtained as described above can be, for example, in the range of 0.005 µm to 3 µm, and preferably in the range of 0.01 µm to 0.3 µm. By setting it to 0.01 µm or more, the continuity of the film is improved, which reduces the possibility of occurrence of a portion where the film is not attached, and by setting it to 0.3 µm or less, there is an advantage in that the possibility of occurrence of peeling due to blistering during a firing treatment in the manufacture of a solar cell element is reduced.

If necessary, the aluminum oxide film obtained as described above can be heated at a predetermined temperature in an oxidizing gas atmosphere such as oxygen, a reducing gas atmosphere such as hydrogen, a water vapor atmosphere containing a large amount of moisture, or a plasma atmosphere such as argon, nitrogen, or oxygen, thereby improving the crystallinity and density of the aluminum oxide film. Residual organic substances, etc. in the obtained aluminum oxide film can be removed by light irradiation such as ultraviolet rays or microwave treatment.

According to the manufacturing method of the present invention, a passive film having an effective lifetime of, for example, 150 to 2000 μs and a recombination speed of, for example, 7 to 100 cm/s when a silicon substrate having a thickness of 300 μm is used can be formed on a silicon substrate. The aluminum oxide film formed by heating and firing can further have a longer effective lifetime and a faster recombination speed by processing in a forming gas atmosphere. Examples of the forming gas include non-oxidizing gases (hydrogen-containing gas, nitrogen-containing gas, etc.).

[Solar cell device]

The present invention includes a solar cell device using a silicon substrate having the passive film of the present invention.

Fig. 5b shows an example of an embodiment of a solar cell element of the present invention. A p-type solar cell element (100) is composed of a p-type silicon semiconductor substrate (11) having a thickness of 180 to 300 μm. On the surface of the light-receiving surface side of (11), an n ⁺ layer (12) which is an n-type impurity layer having a thickness of 0.3 to 1.0 μm, an antireflection and passivation thin film (13) made of a silicon nitride thin film thereon, and a grid electrode (15) made of silver are each formed by a plasma CVD method using SiH ₃ and NH ₃ , a screen printing method using a paste composition containing silver powder, or the like.

On the back surface opposite to the light-receiving side of the silicon semiconductor substrate (11), a passive film (14) made of the aluminum oxide film of the present invention is formed, and an aluminum electrode (16) having a predetermined pattern shape is formed to penetrate (14).

The aluminum electrode (16) is usually formed by applying a paste composition containing aluminum powder by screen printing or the like, drying it, and then firing it for a short time of 1 to 10 seconds at a temperature higher than 660°C, which is the melting point of aluminum. During this firing (fire through), aluminum diffuses into the interior of the silicon semiconductor substrate (11), thereby forming an Al-Si alloy layer (17) between the aluminum electrode (16) and the silicon semiconductor substrate (11), and at the same time, a P ⁺ layer (Back Surface Field (BSF) layer) (18) is formed as an impurity layer due to the diffusion of aluminum atoms.

[Example]

Hereinafter, the present invention will be described in more detail based on examples. However, the examples are merely illustrative of the present invention, and the present invention is not intended to be limited to the examples.

<First aspect of the present invention>

The preparation of the solution containing the alkyl aluminum compound and the solution containing the alkyl aluminum partial hydrolyzate of the present invention was carried out under a nitrogen gas atmosphere, and all solvents were used after being dehydrated and degassed.

<Number of moles of trialkyl aluminum>

The mole number of trialkyl aluminum was calculated from the following formula.

[Number of moles of trialkyl aluminum]

= [Mass of introduced trialkyl aluminum (g)] / [Molecular weight of trialkyl aluminum (114.16 in the case of triethyl aluminum)]

<Measurement of physical properties>

The solvent of the solution containing the alkyl aluminum compound of the present invention, the solution containing the alkyl aluminum partial hydrolyzate, and the solution containing the alkyl aluminum partial hydrolyzate was dried by an evaporator, dissolved in C ₆ D ₆ , and then 1H-NMR measurement was performed using an NMR device (JEOL RESONANCE product "JNM-ECA500").

The solvent of the solution containing the alkyl aluminum partial hydrolyzate of the present invention was dried by an evaporator, and IR measurement was performed by the transmission method using an FT-IR spectrometer (“FT/IR-4100” manufactured by Nippon Bunko Co., Ltd.).

The stability of the solution containing the alkyl aluminum compound of the present invention and the solution containing the alkyl aluminum partial hydrolyzate to air was tested in accordance with Section 3, “Class 3 Test Method,” Section 2, “Spontaneous Combustion Test” of the “Dangerous Goods Identification Test Manual” (Fire Department Dangerous Goods Regulation and Supervision, Shin Nippon Hokyo Publishing Co., Ltd., 1989). A substance that spontaneously combusted on a magnetic cup was classified as Rank 1, a substance that did not spontaneously combust on a magnetic cup but burned the filter paper was classified as Rank 2, and a substance that did not spontaneously combust and did not burn the filter paper was classified as “No Hazard.”

The aluminum oxide thin film produced by the manufacturing method of the present invention was subjected to relative IR measurement using an ATR (Attenuated Total Reflection) method using a ZnSe prism in an FT-IR spectrometer ("FT/IR-4100" manufactured by Nippon Bunko Co., Ltd.) without ATR correction.

Originally, when using a ZnSe prism, it was difficult to measure a thin film having a refractive index exceeding 1.7, and considering that the refractive index of general aluminum oxide is 1.77, it was assumed that measurement would be difficult. However, surprisingly, measurement was possible. It was estimated that the refractive index of the aluminum oxide thin film according to the present invention is 1.7 or less.

The aluminum oxide thin film produced by the manufacturing method of the present invention was cut out of a portion of the film with a knife, and the film thickness was measured using a stylus-type surface shape measuring device (DektakXT-S, manufactured by Vulcano).

[Example 1-1]

Triethylaluminum (Toso Finechem Co., Ltd.) 5.31 g was added to 20.0 g of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) at 25°C and stirred sufficiently to obtain a 21 mass% triethylaluminum NMP solution. When the NMR spectrum was re-measured after 24 hours, the same spectrum as the initially obtained spectrum was obtained.

The 21 mass% triethylaluminum NMP solution obtained in this way was tested for spontaneous ignition and classified as “non-hazardous.”

[Example 1-2]

Trimethylaluminum (manufactured by Tosoh Finechem) 1.32 g was added to 5.00 g of NMP at 25°C and stirred sufficiently to obtain a 21 mass% trimethylaluminum NMP solution. The 21 mass% trimethylaluminum NMP solution thus obtained was tested for spontaneous ignition and classified as “non-hazardous.”

[Example 1-3]

3.48 g of triisobutyl aluminum (manufactured by Tosoh Finechem) was added to 5.00 g of NMP at 25°C and stirred sufficiently to obtain a 41 mass% triisobutyl aluminum NMP solution. The 41 mass% triisobutyl aluminum NMP solution thus obtained was tested for spontaneous ignition and classified as “non-hazardous.”

The results of the spontaneous ignition test up to the above are summarized in Table 1-1.

[Table 1-1]

[Example 1-4]

To 8.01 g of NMP, 0.90 g of mixed xylene and 2.10 g of triethylaluminum were added at 25°C and stirred sufficiently to obtain a 19 mass% triethylaluminum NMP xylene mixed solution. The 19 mass% triethylaluminum NMP xylene mixed solution thus obtained was tested for spontaneous ignition and classified as “non-hazardous.”

[Example 1-5]

To 8.01 g of NMP, 0.90 g of mixed xylene and 2.11 g of trimethylaluminum (manufactured by Tosoh Finechem) were added at 25°C and stirred sufficiently to obtain a 19 mass% trimethylaluminum NMP xylene mixed solution. The 19 mass% trimethylaluminum NMP xylene mixed solution thus obtained was tested for spontaneous ignition and classified as “non-hazardous.”

[Example 1-6]

Triethylaluminum (manufactured by Tosoh Finechem) 8.59 g was added to 20.0 g of NMP at 25°C, and the mixture was stirred sufficiently. Thereafter, 6.77 g of a 20 mass% water NMP solution ([water]/[triethylaluminum] = 1.0) was added dropwise over 50 minutes at 25°C. By continuing stirring at 25°C for 5 hours, a maturation reaction was performed, and a triethylaluminum hydrolyzed composition NMP solution was obtained. When NMR was measured, a spectrum such as Fig. 1a was obtained, and disappearance of the peak corresponding to triethylaluminum was confirmed.

The obtained triethylaluminum hydrolyzed composition NMP solution was solvent-dried using an evaporator at 70°C for 90 minutes, and the IR spectrum was measured by a transmission method, as shown in Fig. 1b. A broad Al-O-Al vibration peak was confirmed in the vicinity of 400 to 1500 cm ^-1 , confirming the formation of Al-O-Al bonds by hydrolysis.

[Example 1-7]

To 18.0 g of NMP, 2.00 g of mixed xylene and 8.59 g of triethylaluminum (manufactured by Tosoh Finechem) were added at 25°C, and the mixture was stirred sufficiently. Thereafter, 6.77 g of a 20 mass% water NMP solution ([water]/[triethylaluminum] = 1.0) was added dropwise over 50 minutes at 25°C. By continuing stirring at 25°C for 5 hours, a maturation reaction was performed, and a triethylaluminum hydrolyzed composition NMP solution was obtained. As a result of NMR measurement, disappearance of the peak corresponding to triethylaluminum was confirmed, similarly to Example 1-6.

[Example 1-8]

The triethylaluminum hydrolysis composition NMP solution obtained in Example 1-6 was dropped 50 μl on a glass substrate (EagleXG, Corning Corporation) measuring 18 mm on each side in an air atmosphere, and applied by spinning at 2000 rpm for 20 seconds using a spin coater. After drying at 25°C for 1 minute, a thin film was formed by heating at 90°C for 5 minutes.

A transparent thin film such as Fig. 1c was obtained, and when the IR was measured by the ATR method, the spectrum as in Fig. 1d was obtained. A broad vibration peak of Al-O-Al was confirmed from 550 to around 1500 cm ^-1 , and a broad vibration peak of Al-OH was confirmed from 2500 to around 4000 cm ^-1 , confirming the formation of Al-O-Al and Al-OH bonds. Therefore, the formation of an aluminum oxide thin film was confirmed. Since there was no vibration peak of an organic substance around 3000 cm ^-1 , it was confirmed that there was no residual organic substance. The IR spectrum of the glass substrate itself by the ATR method is Fig. 1e and is clearly different from Fig. 1d. The film thickness was 638 nm.

<Second aspect of the present invention>

The preparation of solutions containing all organic aluminum compounds and the film formation using them were performed under a nitrogen gas atmosphere, and all solvents were dehydrated and degassed before use.

<Number of moles of trialkyl aluminum>

It is the same as the first aspect of the present invention.

When forming a film on an aluminum oxide film, water was supplied to the film forming atmosphere in a state where water was saturated in nitrogen by bubbling nitrogen into heated water as needed.

The formation of aluminum oxide and its film on the substrate in each film in the examples and comparative examples was confirmed by analysis using infrared spectroscopy using the attenuated total reflection (ATR) method, EPMA (Electron Probe Micro Analyzer), and XRD (X-ray diffraction).

-The transmittance of visible light, etc., was measured using a spectrophotometer.

-The film thickness of the aluminum oxide film was measured using a stylus-type surface profile measuring device or by SEM measurement of the cross-section of the film.

- The adhesion of the formed aluminum oxide film to the substrate was confirmed by a peeling test using adhesive tape such as Scotch tape (registered trademark) (3M product) or cellophane tape to the aluminum oxide film applied to the substrate in accordance with JIS K 5600-5-6 “General testing methods for paints - Part 5: Mechanical properties of coatings - Section 6: Adhesion (crosscut method)”.

-The reactivity of the drug solution was confirmed by dropping the drug solution on a filter paper in a still atmosphere with constant temperature (20℃) and humidity (50%), and visually checking the reactivity on the filter paper.

- The moisture value in the nitrogen atmosphere was converted to volume % by measuring the dew point.

- The nitrogen atmosphere during coating and solvent drying or heating during the film formation was controlled so that the moisture content in the nitrogen gas was in the range of 100 ppm (dew point temperature -42°C) to 375 ppm (dew point temperature -30°C) unless otherwise specifically stated. In addition, by adjusting the settings, it is also possible to adjust it within the range of 5 ppm (dew point temperature -66°C) to 375 ppm (dew point temperature -30°C).

[Example 2-1]

To 73.2 g of tetrahydrofuran (THF) was added 11.35 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) at room temperature. To the TEAL/THF solution obtained by sufficient stirring, while cooling the exotherm caused by the reaction to around 20°C, 36.6 g of a THF solution containing 1.08 g of water was added dropwise while stirring so that the molar ratio of water to TEAL (water/TEAL) became 0.6. Thereafter, the solution was heated to 65°C and reacted at 65°C for 2.5 hours. After completion of the reaction, the solution was allowed to cool and the reaction product was recovered. The product after the reaction was a colorless transparent solution. A trace amount of gel-like insoluble matter contained in the product was filtered through a filter (pore size: 3 μm or less) to recover a colorless transparent solution. Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

In this way, a composition for producing an aluminum oxide film (composition A) containing a product obtained by partially hydrolyzing triethylaluminum was obtained. In addition, with respect to the residue mainly comprising a product obtained by partially hydrolyzing triethylaluminum after removing the solvent, etc. from a part of composition A by vacuum drying, ¹ H-NMR (THF-d ₈ , ppm) was measured to obtain the spectrum of Fig. 2b.

This composition A was applied onto the surface of a glass substrate (Corning Corporation, EagleXG (registered trademark)) measuring 18 mm on each side (thickness 0.7 mm) by spin coating. In a nitrogen atmosphere at room temperature, 50 μl of the solution was dropped onto the glass substrate, and the substrate was rotated at a rotation speed of 1000 rpm for 20 seconds to apply the solution to the entire glass substrate, and after drying at room temperature, the substrate was heated at each predetermined temperature for 2 minutes to dry the solvent and form a film at the same time.

The substrate to which this film was attached was taken out into the air, and the obtained film was analyzed by ATR-IR. It was confirmed that no peaks derived from organic substances such as ethyl groups contained in the solvent or the partial hydrolyzate of triethylaluminum contained in the composition A were observed in the film obtained by heating at any temperature, and that an aluminum oxide film was formed. Fig. 2c shows the results of ATR-IR analysis of a film obtained by heating at 130°C, and Fig. 2d shows the results of only the glass substrate, respectively. All of the obtained films were high in transmittance and transparent, and the vertical transmittance at 550 nm of the films obtained by heating at each temperature obtained the values in Table 2-1.

[Table 2-1]

[Example 2-2]

In Example 2-1, the operation of the coating film was repeated three times, and a film was obtained in the same manner at 300°C. The vertical transmittance at 550 nm of the aluminum oxide film obtained by heating at 300°C was 94%.

[Example 2-3]

To 74.18 g of tetrahydrofuran (THF) was added 27.94 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) at room temperature. To the TEAL/THF solution obtained by sufficient stirring, 38.04 g of a THF solution containing 4.41 g of water was added dropwise while stirring so that the temperature became around 20°C while removing the exotherm caused by the reaction so that the molar ratio of water to TEAL (water/TEAL) became 1.0. Thereafter, the solution was heated to 65°C and reacted at 65°C for 2.5 hours. After completion of the reaction, the solution was allowed to cool and the reaction product was recovered. The product after the reaction was a colorless and transparent solution. A trace amount of gel-like insoluble matter contained in the product was filtered through a filter (pore size: 3 μm or less) to recover a colorless and transparent solution. Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

In this way, a composition for producing an aluminum oxide film (composition B) containing a product obtained by partially hydrolyzing triethylaluminum was obtained. In addition, after removing the solvent, etc. from a part of composition B by vacuum drying, ¹ H-NMR (THF-d ₈ , ppm) was measured for the residue mainly containing the product obtained by partially hydrolyzing triethylaluminum, to obtain the spectrum in Fig. 2e.

Using this composition B, a film was applied to a glass substrate using the same method as in Example 2-1. The heating after application and drying of the solvent was performed for 2 minutes at each temperature of 50, 100, 130, 200, 250, 300, 350, and 400°C. The substrate to which the film obtained at each temperature was attached was taken out into the air, and the film obtained was analyzed by ATR-IR to confirm that no peaks derived from organic substances such as ethyl groups contained in the solvent or partial hydrolyzate of triethylaluminum contained in composition B were confirmed, and that an aluminum oxide film was formed. All of the obtained films were high in transmittance and transparent, and the vertical transmittance at 550 nm of the films obtained by heating at each temperature obtained the values shown in Table 2-2.

[Table 2-2]

[Comparative Example 2-1]

In Example 2-1, the vertical transmittance at 550 nm of the aluminum oxide film obtained by performing the heating temperature after coating at 450°C or 500°C was 79 and 78%, respectively. It was revealed that the heating temperature of the coating film is preferably 400°C or lower.

[Example 2-4]

In Example 2-3, the operation of the coating film was repeated three times, and a film was obtained in the same manner at 350°C. The vertical transmittance at 550 nm of the aluminum oxide film obtained by heating at 350°C was 84%.

[Comparative Example 2-2]

To 150 g of tetrahydrofuran (THF), 15.0 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) was added at room temperature. The mixture was stirred sufficiently to obtain a TEAL/THF solution (composition 1).

As a substrate for forming an aluminum oxide film, a polypropylene (PP) film (30 mm square (0.2 mm thick)) was used, a TEAL/THF solution (composition 1) was used, the amount of composition 1 was 200 μl, the rotation speed was 500 rpm, and the same coating operation as in Example 2-1 was performed, and after drying, the film was heated at 130°C for 2 minutes, and an aluminum oxide film was formed by spin coating. The same analysis of the film formed on the substrate was performed, but there was almost no adhesion of the oxide to the substrate, and the formation of an aluminum oxide film on the polypropylene (PP) film at the low temperature of 130°C could not be confirmed by the film forming method using this solution. In addition, the same operation was performed by changing the substrate from a polypropylene (PP) film to a glass substrate (EagleXG (registered trademark) manufactured by Corning Inc.) measuring 18 mm on each side (thickness 0.7 mm), but the formation of an aluminum oxide film was not confirmed.

The film formation method was changed to an immersion coating method, and under a nitrogen atmosphere, a polypropylene (PP) film (15 mm on each side (30 μm thick)) was immersed in the composition X for 1 second, the film was pulled up, and the resulting liquid was dropped on the film. After the solvent was dried at room temperature, the film was further left at room temperature for 10 minutes or heated at 50°C for 10 minutes, and a film was formed on the polypropylene (PP) film. A similar analysis was performed on the film formed on the substrate, but there was almost no adhesion of the oxide to the substrate, and the formation of an aluminum oxide film on the polypropylene (PP) film at a low temperature of 50°C could not be confirmed by the film formation method using this solution.

[Comparative Example 2-3]

In Example 2-3, except that 4.41 g of water was not added, the same procedure as in Example 2-3 was performed to obtain a TEAL/THF solution (Composition 2) in which TEAL was not partially hydrolyzed. Regarding the reactivity of the chemical solution, when the reactivity on a filter paper was visually confirmed, a pressing effect was observed on the filter paper, and it was found that the TEAL/THF solution in which partial hydrolysis was not performed was difficult to handle as a solution with a high Al concentration.

[Comparative Example 2-4]

In Example 2-2, the amount of tetrahydrofuran (THF) used was 70.0 g, and instead of 27.94 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.), 32.9 g of aluminum triisopropoxide and 4.41 g of water were replaced with 11.6 g of a THF solution containing 2.9 g of water, and the molar ratio of water to Al contained in the aluminum triisopropoxide (water/Al) was added dropwise so that 1 was the molar ratio of water to Al contained in the aluminum triisopropoxide. However, a large amount of white insoluble matter was precipitated, and it was not possible to obtain a uniform coating solution containing a sufficient Al concentration.

[Comparative Example 2-5]

In Example 2-2, 70.0 g of toluene was used instead of 74.18 g of tetrahydrofuran (THF), 32.3 g of aluminum triisopropoxide was used instead of 27.94 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.), and 11.4 g of a THF solution containing 2.84 g of water was used instead of 38.04 g of a THF solution containing 4.41 g of water, so that the molar ratio of water to aluminum triisopropoxide was 1. An attempt was made to obtain a solution in which aluminum triisopropoxide was partially hydrolyzed using the same method as in Example 2-2. In the obtained reaction product, a large amount of white insoluble matter was precipitated, and it was not possible to obtain a uniform coating solution containing a sufficient Al concentration.

[Example 2-5]

To 73.21 g of tetrahydrofuran (THF) was added 11.35 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) at room temperature. To the TEAL/THF solution obtained by sufficient stirring, 36.60 g of a THF solution containing 2.09 g of water was added dropwise while stirring in a temperature range of 20 to 26°C while removing the exotherm caused by the reaction so that the molar ratio of water to TEAL (water/TEAL) became 1.17. Thereafter, the mixture was heated to 65°C and reacted at 65°C for 2.5 hours. After completion of the reaction, the mixture was allowed to cool and the reaction product was recovered. The product after the reaction was a colorless and transparent solution. A trace amount of gel-like insoluble matter contained in the product was filtered through a filter (pore size: 3 μm or less) to recover a colorless and transparent solution. Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

In this way, a composition for producing an aluminum oxide film (composition C) containing a product obtained by partially hydrolyzing triethylaluminum was obtained. In addition, a residue mainly containing a product obtained by partially hydrolyzing triethylaluminum obtained by removing a solvent, etc., from a part of composition C by vacuum drying was subjected to ¹ H-NMR (THF-d ₈ , ppm) measurement, and the spectrum in Fig. 2f was obtained.

Using this composition C, a film was applied to a glass substrate by the same method as in Example 2-1, and the substrate with the film obtained at each temperature attached was taken out into the air, and the obtained film was analyzed by ATR-IR, and it was confirmed that no peaks derived from organic substances such as ethyl groups contained in the solvent or partial hydrolyzate of triethylaluminum contained in the composition C were confirmed, and that an aluminum oxide film was formed. All of the obtained films were high in transmittance and transparent, and the vertical transmittance at 550 nm of the films obtained by heating at each temperature obtained the values shown in Table 2-3.

[Table 2-3]

[Example 2-6]

In Example 2-5, the operation of the coating film was repeated three times, and a film was obtained in the same manner at 300°C. The vertical transmittance at 550 nm of the aluminum oxide film obtained by heating at 300°C was 98%.

[Example 2-7]

To 166.7 g of toluene, 23.5 g of triethyl aluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) was added at room temperature. To the TEAL/THF solution obtained by sufficient stirring, 19.54 g of a THF solution containing 3.92 g of water was added dropwise while stirring to control the exotherm by heat removal at 16 to 27°C so that the molar ratio of water to TEAL (water/TEAL) became 1.06. Then, the solution was heated to 65°C and reacted at 65°C for 2.5 hours. After completion of the reaction, it was allowed to cool and the reaction product was recovered. The product after the reaction was a colorless and transparent solution. A trace amount of gel-shaped insoluble matter contained in the product was filtered through a filter (pore size: 3 μm or less), and the colorless and transparent solution was recovered. Regarding the reactivity of the chemical solution, the reactivity on filter paper was visually confirmed, and no pressing of the filter paper, etc., was observed.

In this way, a composition for producing an aluminum oxide film (composition D) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

Using this composition D, application was performed on a polypropylene (PP) plate (50 mm on each side (3 mm thick)) by the immersion coating method. Under a nitrogen atmosphere, the polypropylene plate was immersed in the composition D for 1 second, the film was pulled up, and the liquid attached to the film was dropped. After drying the solvent at room temperature, it was heated at 50 or 100°C for 10 minutes, and a film was formed on the polypropylene (PP) plate.

The substrates with films attached at each temperature were taken out into the air, and the films obtained were analyzed by ATR-IR. It was confirmed that no peaks derived from organic substances such as the solvent contained in composition D or the ethyl group contained in the partial hydrolyzate of triethylaluminum were observed, and that an aluminum oxide film was formed. All of the films obtained were transparent.

Regarding the adhesion of the obtained film, an adhesion test was conducted in accordance with JIS K 5600-5-6 "General testing methods for paints - Part 5: Mechanical properties of coatings - Section 6: Adhesion (crosscut method)". When Scotch tape (registered trademark) 2364 (product of 3M Corporation) attached to the film was removed, a visual inspection revealed that "Classification 1: There was small peeling of the coating at the intersection of the cuts. The amount affected by the crosscut portion was clearly not less than 5%", confirming that the adhesion of the film to the substrate was good. In addition, when the state of the film was confirmed by ATR-IR and SEM measurements, no strong peeling of the film was confirmed, confirming that the adhesion of the film formed using this composition was high.

[Example 2-8]

In Example 2-7, instead of a polypropylene (PP) film plate, an acrylic plate was used, and a film was formed on the acrylic plate by the same method as in Example 2-3 at a heating temperature of 50°C. The obtained film was analyzed by ATR-IR, and it was confirmed that no peaks derived from organic substances such as the solvent contained in the composition D or the ethyl group contained in the partial hydrolyzate of triethylaluminum were confirmed, and that an aluminum oxide film was formed. Regarding the adhesion of the obtained film, when it was confirmed by the same test as in Example 2-7, it was "classification 1" from the test by the cross-cut method, and strong peeling of the film was not confirmed, confirming that the film formed using this composition had high adhesion.

[Example 2-9]

In Example 2-1, the amount of tetrahydrofuran (THF) used was 108.45 g, the amount of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) used was 15.13 g, and 48.8 g of a THF solution containing 0.95 g of water was added dropwise so that the molar ratio of water to TEAL (water/TEAL) was 0.4. A colorless transparent solution was obtained when the reactivity of the chemical solution was visually confirmed on a filter paper, and no pressing of the filter paper, etc., was observed.

Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper, etc. was observed. In this way, a composition for producing an aluminum oxide film (composition E) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

[Example 2-10]

In Example 2-9, 1.44 g of water was used instead of 0.95 g of water, and the solution was added dropwise so that the molar ratio of water to TEAL (water/TEAL) became 0.6, and a colorless transparent solution was obtained using the same method as Example 2-9. Regarding the reactivity of the chemical solution, the reactivity on a filter paper was visually confirmed, and no pressing of the filter paper, etc. was observed. In this way, a composition for producing an aluminum oxide film (composition F) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

[Example 2-11]

In Example 2-9, 1.91 g of water was used instead of 0.95 g of water, and the solution was added dropwise so that the molar ratio of water to TEAL (water/TEAL) became 0.8, and a colorless transparent solution was obtained using the same method as in Example 2-9. Regarding the reactivity of the chemical solution, the reactivity on a filter paper was visually confirmed, and no pressing of the filter paper, etc. was observed. In this way, a composition for producing an aluminum oxide film (composition G) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

[Example 2-12]

In Example 2-9, 2.79 g of water was used instead of 0.95 g of water, and the solution was added dropwise so that the molar ratio of water to TEAL (water/TEAL) became 1.17, and a colorless transparent solution was obtained using the same method as in Example 2-9. Regarding the reactivity of the chemical solution, the reactivity on a filter paper was visually confirmed, and no pressing of the filter paper, etc. was observed. In this way, a composition for producing an aluminum oxide film (composition H) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

[Example 2-13]

In Example 2-9, 2.98 g of water was used instead of 0.95 g of water, and the solution was added dropwise so that the molar ratio of water to TEAL (water/TEAL) became 1.25, and a colorless transparent solution was obtained using the same method as in Example 2-9. Regarding the reactivity of the chemical solution, the reactivity on a filter paper was visually confirmed, and no pressing of the filter paper, etc. was observed. In this way, a composition for producing an aluminum oxide film (composition I) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

The water/TEAL molar ratio, reaction product appearance, gel formation status, and reactivity of the composition for each composition prepared in Examples 2-9, 10, 11, 12, and 13 are shown in Table 2-4.

[Table 2-4]

[Example 2-14]

To 79.92 g of tetrahydrofuran (THF) was added 11.35 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) at room temperature. To the TEAL/THF solution obtained by sufficient stirring, while reducing the exotherm caused by the reaction to around 20°C, 36.60 g of a THF solution containing 1.79 g of water was added dropwise while stirring so that the molar ratio of water to TEAL (water/TEAL) became 1.0. Thereafter, the solution was heated to 65°C and reacted at 65°C for 2.5 hours. After completion of the reaction, the solution was allowed to cool and the reaction product was recovered. The product after the reaction was a colorless transparent solution. A trace amount of gel-like insoluble matter contained in the product was filtered through a filter (pore size: 3 μm or less) to recover a colorless transparent solution. Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper, etc. was observed. In this way, a composition for producing an aluminum oxide film (composition J) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

[Example 2-15]

To 67.5 g of tetrahydrofuran (THF) was added 24.07 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) at room temperature. To the TEAL/THF solution obtained by sufficient stirring, 12.67 g of isopropanol was added dropwise with stirring while removing the exotherm caused by the reaction at 20 to 27°C. Then, the solution was heated to 65°C and reacted at 65°C for 2.5 hours. After completion of the reaction, the solution was cooled to 18°C, and while removing the exotherm caused by the reaction so that the temperature became around 20°C, 30.05 g of a THF solution containing 3.8 g of water was added dropwise with stirring so that the molar ratio of water to TEAL (water/TEAL) became 1.0. Then, the solution was heated to 65°C and reacted at 65°C for 2.5 hours. The product after the reaction was a colorless transparent solution. A trace amount of gel-shaped insoluble matter contained in this product was filtered through a filter (pore size: 3 μm or less), and a colorless transparent solution was recovered. Regarding the reactivity of the drug solution, the reactivity on filter paper was visually confirmed, and no pressing of the filter paper, etc. was observed. In addition, a portion of the obtained solution was subjected to vacuum drying to remove the solvent, etc., and the residue was analyzed by ^1H -NMR (Fig. 2g) and ^27Al -NMR (Fig. 2h) (all benzene-d ₆ , ppm), confirming that an isopropoxy group exists in the structure of the product.

In this way, a composition for producing an aluminum oxide film (composition K) containing a product obtained by partially hydrolyzing triethylaluminum having an isopropoxy group in the structure was obtained.

Using this composition K, a film was applied to a glass substrate using the same method as in Example 2-1. After application and drying of the solvent, heating was performed at each temperature of 250, 300, 350, and 400°C for 2 minutes. The substrate to which the film obtained at each temperature was attached was taken out into the air, and the film obtained was analyzed by ATR-IR, and it was confirmed that no peaks derived from organic substances such as ethyl groups or isopropoxy groups contained in the solvent contained in composition B or the partial hydrolyzate of triethylaluminum having an isopropoxy group in its structure were confirmed, and that an aluminum oxide film was formed. All of the obtained films were high in transmittance and transparent, and the vertical transmittance at 550 nm of the films obtained by heating at each temperature obtained the values shown in Table 2-5.

[Table 2-5]

[Example 2-16]

A 5 g portion of a composition for producing an aluminum oxide film (composition K) containing a product obtained by partially hydrolyzing triethylaluminum having an isopropoxy group was added to the composition and thoroughly mixed with 5 g of isopropanol, but the mixture remained as a homogeneous solution. The composition for producing an aluminum oxide film (composition K) containing a product obtained by partially hydrolyzing triethylaluminum having an isopropoxy group in its structure can use an alcohol such as isopropanol as a solvent.

[Example 2-17]

In Example 2-15, a composition for producing an aluminum oxide film (composition K) containing a product obtained by partially hydrolyzing triethylaluminum having an isopropoxy group among the structures obtained was collected in an amount of 2.14 g, from which THF was removed, and the solution was concentrated to 0.943 g. The obtained concentrate was a transparent gel-like solid. When 0.25 g of toluene was added to this concentrate and mixed, the solid dissolved to form a homogeneous solution. Thus, the product obtained by partially hydrolyzing triethylaluminum having an isopropoxy group included in the composition for producing an aluminum oxide film (composition K) does not contain inorganic substances such as aluminum oxide or hydroxide that are insoluble in organic solvents.

[Example 2-18]

A 5 g portion of a composition for producing an aluminum oxide film (composition B) containing a product obtained by partially hydrolyzing triethylaluminum obtained in Example 2-2 was added, 5 g of isopropanol was added thereto while stirring at room temperature (20°C), and the reaction was performed until no ethane was generated in the reaction. The obtained solution was uniform, and further, after removing the solvent, etc. by vacuum drying a portion of the obtained solution, ¹ H-NMR (benzene-d ₆ , ppm) was analyzed to confirm that an isopropoxy group was present in the structure of the product.

In this way, a composition for producing an aluminum oxide film (composition L), which is a product obtained by the reaction of a product obtained by partially hydrolyzing triethylaluminum with isopropanol and which has an isopropoxy group in its structure, can be obtained, and this product remains a homogeneous solution even if isopropanol coexists. The solution for producing an aluminum oxide film (composition L) which has an isopropoxy group in its structure, which is obtained by passing through a product obtained by partially hydrolyzing triethylaluminum, can use an alcohol such as isopropanol as a solvent.

[Example 2-19]

To 74.1 g of 1,2-diethoxyethane, 27.91 g of triethyl aluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) was added at room temperature. To the obtained TEAL/THF solution, which was stirred sufficiently, 38 g of a THF solution containing 4.41 g of water was added dropwise while stirring so that the temperature became around 20°C while the exotherm caused by the reaction was reduced so that the molar ratio of water to TEAL (water/TEAL) became 1.0. Thereafter, the solution was heated to 65°C and reacted at 65°C for 2.5 hours. After completion of the reaction, the solution was allowed to cool and the reaction product was recovered. The product after the reaction was a pale yellow transparent solution. A trace amount of gel-like insoluble matter contained in the product was filtered through a filter (pore size: 3 μm or less) to recover a colorless transparent solution. Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

In this way, a composition for producing an aluminum oxide film (composition M) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

[Example 2-20]

To 74.1 g of tetrahydrofuran (THF) was added 27.91 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) at room temperature. To the TEAL/THF solution obtained by sufficient stirring, 38 g of a THF solution containing 4.41 g of water was added dropwise while stirring so that the molar ratio of water to TEAL (water/TEAL) became 1.0 while removing the heat generated by the reaction at 20 to 27°C. Then, the mixture was heated to 65°C and reacted at 65°C for 2.5 hours. After completion of the reaction, the reaction mixture was cooled to 18°C, and 14.69 g of isopropanol was added dropwise while stirring while removing the heat generated by the reaction at 18 to 20°C. Then, the mixture was heated to 65°C and reacted at 65°C for 2.5 hours. The product after the reaction was a colorless transparent solution. A trace amount of gel-shaped insoluble matter contained in this product was filtered through a filter (pore size: 3 ㎛ or less) to recover a colorless transparent solution. Regarding the reactivity of the drug solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

In this way, a composition for producing an aluminum oxide film (composition N) containing a product obtained by partially hydrolyzing triethylaluminum having an isopropoxy group in its structure was obtained. In addition, ^1H -NMR (benzene- _d6 , ppm) measurement was performed on the residue after removing the solvent, etc., from a part of composition N by vacuum drying, to obtain the spectrum of Fig. 2i. This composition N gives almost the same peak pattern as composition K, which is a composition for producing an aluminum oxide film containing a product obtained by partially hydrolyzing triethylaluminum having an isopropoxy group in its structure, and thus, like composition K, can be used for the coating film of an aluminum oxide film.

[Example 2-21]

To 10.0 g of toluene, 1.31 g of triethyl aluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) was added at room temperature (25°C). To the TEAL/THF solution obtained by sufficient stirring, 1.03 g of a THF solution containing 0.21 g of water was added dropwise while stirring while being careful of heat generation so that the molar ratio of water to TEAL (water/TEAL) became 1.0. Then, the mixture was reacted at 25°C for 18 hours. After completion of the reaction, the mixture was cooled and the reaction product was recovered. The product after the reaction was a colorless and transparent solution. A trace amount of gel-shaped insoluble matter contained in the product was filtered through a filter (pore size: 3 μm or less), and the colorless and transparent solution was recovered. Regarding the reactivity of the chemical solution, the reactivity on filter paper was visually confirmed, and no pressing of the filter paper, etc., was observed. A portion of the obtained solution was dried under vacuum to remove the solvent, etc., and the residue mainly composed of a product obtained by partially hydrolyzing triethylaluminum was analyzed by ¹ H-NMR and ²⁷ Al-NMR (both benzene-d ₆ , ppm), and the respective spectra of Fig. 2j ( ¹ H-NMR) and Fig. 2k ( ²⁷ Al-NMR) were obtained. In this way, a composition for producing an aluminum oxide film (composition O) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

Using this composition O, application was performed on a polypropylene (PP) film (15 mm square (30 μm thick)) by the immersion coating method. In a nitrogen atmosphere, a polypropylene (PP) film (15 mm square (30 μm thick)) was immersed in the composition O for 1 second at room temperature, the film was pulled up, and the liquid collected on the film was dropped. After drying the solvent at room temperature, the film was left at room temperature for 10 minutes or heated at 50°C for 10 minutes, and a film was formed on the polypropylene (PP) film.

The substrates with films attached at each temperature were taken out into the air, and the films obtained were analyzed by ATR-IR. It was confirmed that no peaks derived from organic substances such as solvents contained in composition O or ethyl groups contained in the partial hydrolyzate of triethylaluminum were observed, and that an aluminum oxide film was formed. All of the films obtained were transparent.

Regarding the adhesion of the obtained film, a peeling test was performed using a 12 mm wide cellophane tape. The cellophane tape was firmly pressed and attached to the film-forming surface of the polypropylene (PP) film on which the aluminum oxide film was formed, and was peeled off at an incline of 45°. After peeling, the film was visually checked by ATR-IR and SEM measurements, and no strong peeling of the film was observed, confirming that the film formed by the present composition had high adhesion.

[Example 2-22]

In Example 2-21, a film was formed on a polypropylene (PP) film using the same method as in Example 2-22, except that the heating was performed in air at 50°C for 10 minutes in a nitrogen atmosphere.

The obtained film was analyzed by ATR-IR, and it was confirmed that no peaks derived from organic substances such as the solvent contained in the composition O or the ethyl group contained in the partial hydrolyzate of triethylaluminum were observed, and that an aluminum oxide film was formed. The obtained film was transparent.

Regarding the adhesion of the obtained film, the same test as in Example 2-21 was performed, and no strong peeling of the film was observed, confirming that the adhesion of the film formed using this composition was high.

[Example 2-23]

In Example 2-21, instead of the polypropylene (PP) film (15 mm square (30 µm thick), a porous polypropylene (PP) film (for secondary battery separator: 15 mm square (20 µm thick)) was used, and a film was formed on the porous polypropylene (PP) film by the same method as in Examples 2-21 and 2-22. The obtained film was analyzed by ATR-IR, and it was confirmed that no peaks derived from organic substances such as the solvent contained in the composition O or the ethyl group contained in the partial hydrolyzate of triethylaluminum were confirmed, and that an aluminum oxide film was formed. The results of the ATR-IR analysis of a film obtained by heating at 50°C in a nitrogen atmosphere in Fig. 2l, a film obtained by heating at 50°C in an air atmosphere in Fig. 2m, and a porous polypropylene (PP) film on which no film was formed in Fig. 2n are shown, respectively. When the surface was analyzed by EPMA, Al and The presence of O(oxygen) was confirmed.

Regarding the adhesion of the obtained film, the same test as in Example 2-21 was performed, and no strong peeling of the film was observed, confirming that the adhesion of the film formed using this composition was high.

[Example 2-24]

In Example 2-21, instead of a polypropylene (PP) film (15 mm square (30 µm thick), a glass substrate (Corning Corporation, EagleXG (registered trademark)) having a square size of 18 mm (thickness of 0.7 mm) was used, and a film was formed on the glass substrate by the same method as in Examples 2-21 and 2-22. The heating temperature after coating was room temperature (no heating), 50, 100, 200, 300, 400, and 500°C, respectively.

The obtained film was analyzed by ATR-IR, and it was confirmed that no peaks derived from organic substances such as the solvent contained in the composition O or the ethyl group contained in the partial hydrolyzate of triethylaluminum were confirmed, and that an aluminum oxide film was formed. In addition, the film heated at 50° C. under a nitrogen atmosphere was taken out into the air, and the film thickness was measured by SEM analysis, as shown in Fig. 2o, and the film thickness calculated therefrom was 470 nm. In addition, SEM analysis was performed on the surface of the film, and the result of Fig. 2p was obtained.

Regarding the adhesion of the obtained film, the same test as in Example 2-21 was performed, and no strong peeling of the film was observed, confirming that the adhesion of the film formed using this composition was high.

[Example 2-25]

In Example 2-21, instead of a polypropylene (PP) film (15 mm square (30 μm thick), a polyethylene terephthalate (PET) film (15 mm square (25 μm thick) and 30 mm square (188 μm)) was used, and a film was formed on the PET film using the same method as in Examples 2-21 and 2-22. Heating after coating and drying was performed at room temperature (no heating), 50, 100, and 130°C for 2 minutes each.

The obtained film was analyzed by ATR-IR, and it was confirmed that no peaks derived from organic substances, such as the solvent contained in the composition O or the ethyl group contained in the partial hydrolyzate of triethylaluminum, were observed, and that an aluminum oxide film was formed.

Regarding the adhesion of the film obtained at 100°C and 130°C, the same test as in Example 2-21 was performed, and no strong peeling of the film was observed, confirming that the adhesion of the film formed using this composition was high.

[Example 2-26]

In Example 2-21, 3.43 g of the composition O prepared was weighed under a nitrogen atmosphere, 2.29 g of toluene was added, and the mixture was stirred to obtain a uniform solution. This uniform solution was used as a composition for producing an aluminum oxide film containing a product obtained by partially hydrolyzing triethylaluminum (composition P). Regarding the reactivity of the chemical solution, the reactivity on a filter paper was visually confirmed, and no pressing of the filter paper, etc., was observed.

[Example 2-27]

To 10.0 g of toluene, 3.13 g of triethyl aluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) was added at room temperature (25°C). To the TEAL/THF solution obtained by sufficient stirring, 2.46 g of a THF solution containing 0.49 g of water was added dropwise while stirring while being careful of heat generation so that the molar ratio of water to TEAL (water/TEAL) became 1.0. Then, the mixture was reacted at 25°C for 18 hours. After completion of the reaction, the mixture was cooled and the reaction product was recovered. The product after the reaction was a colorless and transparent solution. A trace amount of gel-shaped insoluble matter contained in the product was filtered through a filter (pore size: 3 μm or less), and the colorless and transparent solution was recovered. Regarding the reactivity of the chemical solution, the reactivity on filter paper was visually confirmed, and no pressing of the filter paper, etc., was observed.

In this way, a composition for producing an aluminum oxide film (composition Q) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

[Example 2-28]

To 10.0 g of toluene, 5.83 g of triethyl aluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) was added at room temperature (25°C). To the TEAL/THF solution obtained by sufficient stirring, 4.55 g of a THF solution containing 0.91 g of water was added dropwise while stirring while being careful of heat generation so that the molar ratio of water to TEAL (water/TEAL) became 1.0. Then, the mixture was reacted at 25°C for 18 hours. After completion of the reaction, the mixture was cooled and the reaction product was recovered. The product after the reaction was a colorless and transparent solution containing white insoluble matters. The white insoluble matters contained in the product were filtered through a filter (pore size: 3 μm or less), and the colorless and transparent solution was recovered. Regarding the reactivity of the chemical solution, the reactivity on filter paper was visually confirmed, and no pressing of the filter paper, etc., was observed.

In this way, a composition for producing an aluminum oxide film (composition R) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

[Example 2-29]

To 10.0 g of toluene, 12.3 g of triethyl aluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) was added at room temperature (25°C). To the TEAL/THF solution obtained by sufficient stirring, 8.13 g of a THF solution containing 1.63 g of water was added dropwise while stirring while being careful of heat generation so that the molar ratio of water to TEAL (water/TEAL) became 1.0. Then, the mixture was reacted at 25°C for 18 hours. After completion of the reaction, the mixture was cooled and the reaction product was recovered. The product after the reaction was a colorless and transparent solution containing white insoluble matters. The white insoluble matters contained in the product were filtered through a filter (pore size: 3 μm or less), and the colorless and transparent solution was recovered. Regarding the reactivity of the chemical solution, the reactivity on filter paper was visually confirmed, and no pressing of the filter paper, etc., was observed.

In this way, a composition for producing an aluminum oxide film (composition S) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

[Example 2-30]

To 10.0 g of tetrahydrofuran (THF) was added 1.31 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) at room temperature (25°C). To the TEAL/THF solution obtained by sufficient stirring, 1.03 g of a THF solution containing 0.21 g of water was added dropwise while stirring while being careful of heat generation so that the molar ratio of water to TEAL (water/TEAL) became 1.0. Then, the mixture was reacted at 25°C for 18 hours. After completion of the reaction, the mixture was cooled and the reaction product was recovered. The product after the reaction was a colorless and transparent solution containing white insoluble matters. The white insoluble matters contained in the product were filtered through a filter (pore size: 3 μm or less), and the colorless and transparent solution was recovered. Regarding the reactivity of the chemical solution, the reactivity on filter paper was visually confirmed, and no pressing of the filter paper, etc., was observed.

In this way, a composition for producing an aluminum oxide film (composition T) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

[Example 2-31]

To 10.0 g of tetrahydrofuran (THF) was added 5.83 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) at room temperature (25°C). To the TEAL/THF solution obtained by sufficient stirring, 4.58 g of a THF solution containing 0.92 g of water was added dropwise while stirring while being careful of heat generation so that the molar ratio of water to TEAL (water/TEAL) became 1.0. Then, the mixture was reacted at 25°C for 18 hours. After completion of the reaction, the mixture was cooled and the reaction product was recovered. The product after the reaction was a colorless and transparent solution containing white insoluble matters. The white insoluble matters contained in the product were filtered through a filter (pore size: 3 μm or less), and the colorless and transparent solution was recovered. Regarding the reactivity of the chemical solution, the reactivity on filter paper was visually confirmed, and no pressing of the filter paper, etc., was observed.

In this way, a composition for producing an aluminum oxide film (composition U) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

[Example 2-32]

To 20.0 g of tetrahydrofuran (THF) was added 2.22 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) at room temperature (25°C). To the TEAL/THF solution obtained by sufficient stirring, 3.50 g of a THF solution containing 0.42 g of water was added dropwise while stirring while being careful of heat generation so that the molar ratio of water to TEAL (water/TEAL) became 1.2. Thereafter, the temperature was increased to 65°C, and the mixture was reacted at 65°C for 2.5 hours. After completion of the reaction, the mixture was cooled and the reaction product was recovered. The product after the reaction was a colorless transparent solution containing a trace amount of gel-like insoluble matter. The trace amount of gel-like insoluble matter contained in the product was filtered through a filter (pore size: 3 μm or less) to recover the colorless transparent solution. Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

In this way, a composition for producing an aluminum oxide film (composition V) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

This composition V was applied onto the surface of a glass substrate (Corning Corporation, EagleXG (registered trademark)) measuring 18 mm on each side (thickness 0.7 mm) by spin coating. In a nitrogen atmosphere at room temperature, 50 μl of the solution was dropped onto the glass substrate, and the substrate was rotated at a rotation speed of 1000 rpm for 20 seconds to apply the solution to the entire glass substrate, and after drying at room temperature, the substrate was heated at each predetermined temperature for 2 minutes to dry the solvent and form a film at the same time.

The substrate with this film attached was taken out into the air, and the obtained film was analyzed by ATR-IR to confirm the formation of an aluminum oxide film. All the obtained films were highly transmittance and transparent, and the vertical transmittance at 550 nm of the films obtained by heating at each temperature obtained the values in Table 2-6. In addition, the film thickness of the film heated at 130°C was measured by a stylus-type surface profile measuring instrument, and it was 178 nm.

[Table 2-6]

[Example 2-33]

In Example 2-32, the operation of forming a film was repeated three times, and a film was obtained in the same manner at 300°C. The vertical transmittance at 550 nm of the aluminum oxide film obtained by heating at 300°C was 85%.

[Example 2-34]

To 20.0 g of tetrahydrofuran (THF) was added 1.05 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) at room temperature (25°C). To the TEAL/THF solution obtained by sufficient stirring, 1.66 g of a THF solution containing 0.20 g of water was added dropwise while stirring while being careful of heat generation so that the molar ratio of water to TEAL (water/TEAL) became 1.2. Thereafter, the temperature was increased to 65°C and the mixture was reacted at 65°C for 2.5 hours. After completion of the reaction, the mixture was cooled and the reaction product was recovered. The product after the reaction was a colorless transparent solution containing a trace amount of gel-like insoluble matter. The trace amount of gel-like insoluble matter contained in the product was filtered through a filter (pore size: 3 μm or less) to recover the colorless transparent solution. Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper, etc. was observed. In this way, a composition for producing an aluminum oxide film (composition W) containing a product obtained by partially hydrolyzing triethylaluminum was obtained. Using this composition W, a film was applied to a glass substrate by the same method as in Example 2-33, and the results shown in Table 2-7 were obtained. In addition, the film thickness of the film heated at 130°C was measured with a stylus-type surface profile measuring device, and was 146 nm.

[Table 2-7]

[Example 2-35]

In Example 2-34, the operation of forming a film was repeated three times, and a film was obtained in the same manner at 300°C. The vertical transmittance at 550 nm of the aluminum oxide film obtained by heating at 300°C was 92%.

[Example 2-36]

In Example 2-7, a composition for producing an aluminum oxide film (Composition D) containing a product obtained by partially hydrolyzing triethylaluminum so that the molar ratio of water to TEAL (water/TEAL) is 1.06 was used, and a polypropylene (PP) film (30 mm square (0.2 mm thick)) was used as a substrate for forming an aluminum oxide film. In a nitrogen atmosphere, at room temperature, 200 μl of the solution was dropped onto the film, the substrate was rotated at a rotation speed of 500 rpm for 20 seconds to apply the solution to the entire film, and after drying the solvent, the substrate was heated at each of 50, 100, and 130°C for 2 minutes to dry the solvent and form a film at the same time.

The substrates to which these films were attached were taken out into the air, and the obtained films were analyzed by ATR-IR. It was confirmed that no peaks derived from organic substances, such as the solvent contained in the composition D or the ethyl group contained in the partial hydrolyzate of triethylaluminum, were observed, and that an aluminum oxide film was formed. All the obtained films were transparent at each temperature.

The adhesion of the film obtained by heating at each temperature was confirmed by a peeling test using a 12 mm wide cellophane tape. The cellophane tape was firmly pressed and attached to the film-forming surface of the polypropylene (PP) film on which an aluminum oxide film was formed, and was peeled off at an incline of 45°. After peeling, visual, ATR-IR, and SEM measurements were performed to confirm that no strong peeling of the film was confirmed, and it was confirmed that the adhesion of the film formed by the present composition was high even in heat treatment at a low temperature of 130°C or lower. Among these, the adhesion of the film was particularly good even when formed at 130°C.

[Example 2-37]

Using each of the compositions for producing an aluminum oxide film containing a product obtained by partially hydrolyzing triethylaluminum, each of the compositions O obtained in Example 2-21, P obtained in Example 2-26, Q obtained in Example 2-27, R obtained in Example 2-28, T obtained in Example 2-30, and U obtained in Example 2-31 (compositions O, P, Q, R, T, and U all have a molar ratio of water to TEAL (water/TEAL) of 1.0), a film was applied by spin coating in the same manner as in Example 2-36, and after drying the solvent, the film was formed on a polypropylene (PP) film (30 mm on each side (0.2 mm thick)) by heating at each temperature of 50, 100, and 130°C for 2 minutes. The substrates to which these films were attached were taken out into the air, and the obtained films were analyzed by ATR-IR. It was confirmed that no peaks derived from organic substances, such as ethyl groups contained in the solvent or partial hydrolyzate of triethylaluminum contained in each composition, were observed, and that an aluminum oxide film was formed.

[Example 2-38]

Using the compositions for producing an aluminum oxide film containing a product partially hydrolyzed of triethylaluminum, each of the compositions D obtained in Example 2-7 (the molar ratio of water to TEAL (water/TEAL) was 1.06), E obtained in Example 2-9 (the molar ratio of water to TEAL (water/TEAL) was 0.4), F obtained in Example 2-10 (the molar ratio of water to TEAL (water/TEAL) was 0.6), G obtained in Example 2-11 (the molar ratio of water to TEAL (water/TEAL) was 0.8), H obtained in Example 2-12 (the molar ratio of water to TEAL (water/TEAL) was 1.17), and I obtained in Example 2-13 (the molar ratio of water to TEAL (water/TEAL) was 1.25), a film was applied by spin coating in the same manner as in Example 2-36, and after drying the solvent, 50, It was heated at each temperature of 100 and 130℃ for 2 minutes, and a film was formed on a polypropylene (PP) film (30 mm square (0.2 mm thick)).

The polypropylene (PP) films to which these films were attached were taken out into the air, and the obtained films were analyzed by ATR-IR. It was confirmed that no peaks derived from organic substances such as ethyl groups contained in the solvent or partial hydrolyzate of triethylaluminum contained in each composition were observed, and that an aluminum oxide film was formed. All the obtained films at each temperature were transparent.

In addition, the adhesion of the obtained film was confirmed by a peeling test using Scotch tape (registered trademark) 2364 (3M product) used in the cross-cut test of Example 2-7. The tape was firmly pressed and attached to the film-forming surface of the polypropylene (PP) film on which an aluminum oxide film was formed, and then peeled off at an angle of 45°. After peeling, the film was confirmed with the naked eye, ATR-IR, and SEM measurements, and no strong peeling of the film was confirmed, confirming that the film formed by the present composition had high adhesion. In these obtained films, coating was performed using Composition D (the molar ratio of water to TEAL (water/TEAL) was 1.06), Composition G (the molar ratio of water to TEAL (water/TEAL) was 0.8), Composition H (the molar ratio of water to TEAL (water/TEAL) was 1.17), and Composition I (the molar ratio of water to TEAL (water/TEAL) was 1.25), and the films obtained by heating at 100°C or higher had good adhesion to a polypropylene (PP) film. The ATR-IR spectra of the aluminum oxide film before and after a peeling test was performed on the aluminum oxide film formed on the PP film at 100°C using Composition H (the molar ratio of water to TEAL (water/TEAL) was 1.17) are shown in FIGS. 2q and 2r ( FIG. 2q : before the peeling test, FIG. 2r : after the peeling test).

[Comparative Example 2-6]

In Example 2-1, the amount of tetrahydrofuran (THF) used was 108.45 g, the amount of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) used was 15.13 g, and 48.8 g of a THF solution containing 0.48 g of water was added dropwise instead of 36.6 g of a THF solution containing 1.08 g of water, so that the molar ratio of water to TEAL (water/TEAL) was 0.2, and a colorless transparent solution was obtained. Regarding the reactivity of the chemical solution, the reactivity on a filter paper was visually confirmed, and no pressing of the filter paper, etc. was observed.

In this way, a composition for producing an aluminum oxide film (composition 3) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

A composition for producing an aluminum oxide film (Composition 3) containing a product obtained by partially hydrolyzing triethylaluminum so that the molar ratio of water to TEAL (water/TEAL) is 0.2 was used, and a polypropylene (PP) film (30 mm square (0.2 mm thick)) was used as a substrate for forming an aluminum oxide film, and the same operation as in Example 2-1 was performed to form an aluminum oxide film by spin coating. At this time, after applying Composition 3 and drying the solvent, the film was heated at each temperature of 130°C for 2 minutes. The substrate to which the film obtained by heating to each of these temperatures was attached was taken out into the air, and the obtained film was analyzed by ATR-IR to obtain the spectrum of Fig. 2s. As is clear from FIG. 2s, compared to FIG. 2q of Example 2-38, the peak derived from the PP substrate is larger than the peak of the aluminum oxide, and the molar ratio of water to TEAL (water/TEAL) is 0.2, and it was confirmed that the aluminum oxide film obtained by the film formation using the composition for producing an aluminum oxide film (Composition 3) containing a product obtained by partially hydrolyzing triethylaluminum was thinner than the film obtained by the film formation using the composition of the present invention.

In addition, regarding the adhesion of the obtained film, a peeling test was performed using Scotch tape (registered trademark) 2364 (product of 3M) used in the crosscut test of Example 2-7, and the peeling test was analyzed by ATR-IR and SEM measurements. The ATR-IR spectrum of the aluminum oxide film after the peeling test was performed on the aluminum oxide film formed on a PP film at 100°C using composition 3 is shown in Fig. 2t. In the spectrum of Fig. 2t, it was confirmed that not only was the adhesion of the oxide small during the film formation, but also the film was easy to peel off, since the peak of the aluminum oxide is decreasing.

Thus, it was confirmed that the product in which triethylaluminum was partially hydrolyzed so that the molar ratio of water to TEAL (water/TEAL) used in this comparative example was 0.2 had inferior film-forming properties and adhesiveness compared to the composition obtained when the molar ratio of water to TEAL (water/TEAL) used in Example 2-38 was 0.4 to 1.25.

[Comparative Example 2-7]

To 18.38 g of aluminum triisopropoxide, 90 ml of isopropanol was added, and 1.62 g of water was added dropwise at room temperature with stirring so that the molar ratio to aluminum triisopropoxide became 1. Then, the temperature was increased to 80°C, and the reaction was performed at 80°C for 3 hours. After completion of the reaction, the mixture was cooled and the contents were recovered, but most of the aluminum triisopropoxide was recovered as unreacted material.

[Comparative Example 2-8]

109.25 g of water was heated to 72°C, and 41.8 g of aluminum triisopropoxide was added with stirring. The mixture was heated at 85°C for 4 hours and then cooled to room temperature. The solution was in a gel form and stirring was difficult. Furthermore, 1.89 g of 60 wt% nitric acid was added to obtain a gel-like substance that appeared white. This solution was heated at 91°C for 3 hours. It was then cooled to room temperature to obtain a gel-like substance. Since the dispersion of this gel-like substance in the liquid was poor, 200 g of water was added to dilute it, and it became a milky white cloudy translucent liquid, which was recovered (Composition 4).

As a substrate for forming an aluminum oxide film, a polypropylene (PP) film (30 mm square (0.2 mm thick)) was used, and the composition 4 was used, and the same operation as in Example 2-1 was performed to form an aluminum oxide film by spin coating. At this time, after applying the composition 4 and drying the solvent, the film was heated at 130°C for 2 minutes. Almost no composition 4 remained on the film surface, so that a film could not be formed. Film formation by immersion coating was also attempted, but, as with spin coating, a film could not be formed. In addition, after the composition 4 was spread as much as possible on the polypropylene (PP) film and then heated at 60°C, an attempt was made to form an aluminum oxide film, but a transparent film-like material was formed in fragments, but it was all peeled off from the film.

The results of evaluating the adhesion of films obtained by spin coating on PP films using each composition obtained in Example 2-38 and Comparative Examples 2-2 and 2-6 are shown in Tables 2-8 and 2-9.

[Table 2-8]

[Table 2-9]

[Example 2-39]

In Example 2-13, when the water/THF solution was additionally added dropwise so that the molar ratio of water to TEAL (water/TEAL) became 1.27 or 1.29, a white insoluble substance was generated (10% or less in terms of the volume of solid matter in the solution). When the appearance of the composition was observed after the solution was left at room temperature (20 to 25°C) for 3 days, there was almost no increase in the white insoluble matter that occurred when the water/THF solution was additionally added, and by removing these insoluble matters, it was possible to obtain a composition for producing an aluminum oxide film as a uniform solution containing a product obtained by partially hydrolyzing triethylaluminum (Composition X (water/TEAL = 1.27) and Composition Y (water/TEAL = 1.29). These compositions were applied to a substrate such as glass or resin by the spin coating film formation or immersion coating film formation described in Example 2 of the present invention, and further heated to form an aluminum oxide film. Regarding the compositions for producing an aluminum oxide film containing a product obtained by partially hydrolyzing triethylaluminum, each having a molar ratio of water to TEAL (water/TEAL) of 0.4 to 1.25 obtained in Examples 2-9 to 2-13, the solution was also left at room temperature (20 to 25°C) for 3 days. The appearance of the composition after standing was observed with the naked eye, and no changes were observed in the solution.

[Comparative Example 2-9]

In Example 2-13, when the water/THF solution was additionally added dropwise so that the molar ratio of water to TEAL (water/TEAL) was 1.31, 1.33, or 1.35, a large amount of white insoluble matter was generated (15% or more in terms of volume in the solution). When the appearance of the composition was observed after leaving the solution for 3 days, the entire solution had formed a gel, there was almost no uniform solution portion, and the fluidity as a solution was almost lost. When the molar ratio of water to TEAL (water/TEAL) was this high, it became difficult to obtain the composition as a uniform solution, making it difficult to use it as a coating agent.

The appearance of the reaction products obtained by partial hydrolysis of TEAL at each water/TEAL (molar ratio) in Example 2-39 and Comparative Example 2-9 and the occurrence of insoluble gels (immediately after preparation and after 3 days of standing) are shown in Tables 2-10 and 2-11.

[Table 2-10]

[Table 2-11]

[Example 2-40]

In Example 2-7, a composition for producing an aluminum oxide film (composition D) containing a product obtained by partially hydrolyzing triethylaluminum so that the molar ratio of water to TEAL (water/TEAL) is 1.06 was used, and paper (about a bag: (square 20 mm (thickness 31 μm)) was used as a substrate for forming an aluminum oxide film, and application was performed by the dipping coating method. Under a nitrogen atmosphere, the paper was dipped in composition D for 1 second, the paper was pulled up, and the liquid accumulated on the paper was dropped. After the solvent was dried at room temperature, it was heated at 200° C. for 2 minutes, and a film was formed on the paper. The paper with the obtained film attached was taken out into the air, and the obtained film was analyzed by ATR-IR, and it was confirmed that no peaks derived from organic substances such as ethyl groups contained in the solvent or the partially hydrolyzed product of triethylaluminum contained in composition D were confirmed, and the formation of an aluminum oxide film was confirmed. The obtained film was analyzed by SEM, and as shown in FIG. 2u was obtained, and it was confirmed that the surface of the paper fibers was coated with aluminum oxide.

[Example 2-41]

In Example 2-40, instead of paper (bag: (20 mm square (31 ㎛ thick)) as a substrate for forming an aluminum oxide film, a glass substrate (Corning Corporation, EagleXG (registered trademark)) having a square size of 18 mm (thickness of 0.7 mm) was used, and coating was performed by the dipping coating method. Under a nitrogen atmosphere, the glass substrate was dipped in Composition D for 1 second, the glass substrate was lifted, and the liquid accumulated on the substrate was dropped. After the solvent was dried at room temperature, it was heated at 130°C for 2 minutes, and a film was formed on the substrate. During this series of film-forming operations of coating, solvent drying, and heating, the moisture content was 246 to 304 ppm (dew point temperature of -32 to 34°C) in the nitrogen gas atmosphere.

The substrate with the obtained film attached was taken out into the air, and the obtained film was analyzed by ATR-IR. It was confirmed that no peaks derived from organic substances such as the solvent contained in the composition D or the ethyl group contained in the partial hydrolyzate of triethylaluminum were observed, and that an aluminum oxide film was formed. The appearance of the obtained aluminum oxide film was transparent and homogeneous.

[Comparative Example 2-10]

In Example 42-1, a film was formed on a glass substrate in the same manner as in Example 2-41, except that during the series of film-forming operations of coating, solvent drying, and heating, the moisture content was set to 9312 mol ppm to 9778 ppm (approximately 1%) (dew point temperature -6 to -7°C) in a nitrogen gas atmosphere.

The substrate with the obtained film attached was taken out into the air, and the obtained film was analyzed by ATR-IR. It was confirmed that no peaks derived from organic substances such as the solvent contained in the composition D or the ethyl group contained in the partial hydrolyzate of triethylaluminum were confirmed, and that an aluminum oxide film was formed. However, a part of the obtained aluminum oxide film was in the form of powder, and it could not be obtained as a homogeneous film.

[Example 2-42]

Any of the substrates to which the aluminum oxide films obtained in Examples 2-1, 2-2, 2-3, 2-4, 2-5, 2-15, 2-32, 2-33, and 2-34 were attached had a vertical transmittance of 80% or higher at 550 nm, and thus could be used as an optical material. In addition, the aluminum oxide film formed on a glass substrate showed no deterioration even when heated at 500°C after the film formation, and thus could be used as a heat-resistant material. When the surface resistance of these films was measured, no resistance value was obtained, indicating that there was no conductivity, and thus it could be used as an insulating material. The substrate to which the aluminum oxide film of Example 2-24 was attached was confirmed to have fine unevenness on the surface of the film obtained by the film formation, and thus it could be used for an antireflection effect and as a catalyst carrier. In Examples 2-7, 8, 21, 22, 23, 24, 25, 36, 37, 38, and 40, the aluminum oxide film formed from the composition of the present invention has high adhesion to substrates such as glass, resin, and paper, and therefore can be used as a protective film for various substrates, a base for a coating or a laminated film, an undercoat film, a film for electronic devices that can be laminated on a substrate, and the like. In this way, the substrate to which the aluminum oxide film of the present invention is attached can be used as an aluminum oxide functional film.

[Example 2-43]

The glass substrates having the aluminum oxide films described in Examples 2-1, 2, 3, 4, 5, 6, 15, 24, 32, 33, 34, 35 and 39, or the plates and films or papers made of resins such as polypropylene (PP), polyethylene terephthalate (PET) and acrylic having the aluminum oxide films obtained in Examples 2-7, 8, 21, 22, 23, 25, 36, 37, 38, 39 and 40 can all be used as substrates having the aluminum oxide functional films having the functions described in Example 42.

<Third aspect of the present invention>

The preparation of solutions containing all organic aluminum compounds and the film formation using them were performed under a nitrogen gas atmosphere, and all solvents were dehydrated and degassed before use.

<Number of Triethyl Aluminum Moles>

It is the same as the first aspect of the present invention.

When forming a film on an aluminum oxide film, water was supplied to the film formation atmosphere in a state where water was saturated in nitrogen (25 mol% as moisture in an inert gas) by bubbling nitrogen into water heated to 65°C as needed. The moisture content in the inert gas in the film formation atmosphere could be determined by dew point measurement (humidity). In addition, when performing operations such as solution preparation or film formation at room temperature, the operations were performed in an environment where the room temperature was 18 to 27°C.

The formation of aluminum oxide and its film on the substrate in each film in the examples and comparative examples was confirmed by analysis using infrared spectroscopy using the attenuated total reflection (ATR) method, EPMA (Electron Probe Micro Analyzer), and XRD (X-ray diffraction).

The transmittance of visible light, etc. was measured using a spectrophotometer.

The film thickness of the aluminum oxide film was measured using a stylus-type surface profile measuring instrument or by SEM measurement of the cross-section of the film.

The adhesion of the formed aluminum oxide film to the substrate was confirmed by a peeling test in which the aluminum oxide film applied to the substrate using an adhesive tape was pasted and peeled off.

The reactivity of the drug solution was confirmed by dropping the drug solution on a filter paper in a still atmosphere with constant temperature (20°C) and humidity (50%), and visually checking the reactivity on the filter paper.

[Example 3-1-1]

To 74.8 g of tetrahydrofuran (THF), 8.3 g of triethylaluminum (manufactured by Tosoh Finechem Co., Ltd.) was added at room temperature. After sufficient stirring, the mixture was filtered to obtain a solution (solution A) for producing an aluminum oxide film containing triethylaluminum for use in spray coating.

Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

Using the obtained solution for producing an aluminum oxide film (solution A), an aluminum oxide film was formed by spray deposition. As a substrate for forming an aluminum oxide film, a glass substrate (EagleXG (registered trademark) manufactured by Corning Inc.) with a side size of 18 mm (thickness of 0.7 mm) was used. The glass substrate was heated to 200°C, and in a nitrogen atmosphere containing 2.3 mol% of water (90% relative humidity at 21°C) in an inert gas at atmospheric pressure, solution A was sprayed from a spray nozzle at 2 mL/min for 8 minutes onto the substrate heated with a heater. The size of the droplets discharged from the spray nozzle was in the range of 3 to 20 μm, and the distance between the spray nozzle and the substrate was set to 20 cm. After completion of spraying, the substrate on which the film was formed was continuously heated for 5 minutes.

The film formed on the glass substrate was taken out into the air after cooling, and analyzed by SEM and EPMA to confirm that the adhesion of the film and the elements constituting the film were oxygen and aluminum elements, and further, when analyzed by ATR-IR, it was confirmed that an increase in the peak overlapping with the peak derived from the glass substrate around 550 to 1000 cm ^-1 and a peak attributed to CH which the organoaluminum compound or solvent has in its structure, which appeared between 2800 and 3100 ^cm -1, were not observed. From the above analysis, it was confirmed that an aluminum oxide film was formed at a low temperature of 200°C by the film-forming method using this solution. In addition, the aluminum oxide film obtained in this example was confirmed to be in an amorphous state because no peak was confirmed by XRD. The film thickness of the aluminum oxide film was 329 nm as measured by a stylus-type surface profile measuring device. In addition, the transmittance in visible light (550 nm) was 97.9%, and a transparent aluminum oxide film with a transmittance of 80% or more was obtained.

Using a solution having the same composition as the solution for producing an aluminum oxide film containing triethylaluminum (solution A) of Example 3-1-1, the film formation described in Example 3-1-1 was performed once more, thereby obtaining an aluminum oxide film having a film thickness of 332 nm. This film was analyzed using SEM, and it was confirmed that the surface structure of the film had the shape of Fig. 3b, and the cross-sectional structure of the film had the shape of Fig. 3c, respectively.

[Example 3-1-2]

In Example 3-1-1, 76.5 g of tetrahydrofuran (THF) and 4.0 g of triethylaluminum (manufactured by Tosoh Finechem Co., Ltd.) were used, and the same operation as in Example 3-1-1 was performed to obtain a solution for producing an aluminum oxide film containing triethylaluminum for use in spray coating (solution B).

Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

Using the obtained solution for producing an aluminum oxide film (solution B), the same operation as in Example 3-1-1 was performed to form an aluminum oxide film by spray deposition. By the same analysis of the film formed on the substrate, the formation of an aluminum oxide film at a low temperature of 200°C was confirmed by the film deposition method using this solution. The film thickness of the aluminum oxide film formed on the glass substrate was 279 nm. The transmittance of the obtained film in visible light (550 nm) was 94.8%, and a transparent aluminum oxide film having a transmittance of 80% or more was obtained.

[Example 3-1-3]

In Example 3-1-1, 79.2 g of 1,2-diethoxyethane was used instead of tetrahydrofuran (THF), and 8.8 g of triethylaluminum (manufactured by Tosoh Finechem Co., Ltd.) was used, and the same operation as in Example 3-1-1 was performed to obtain a solution for producing an aluminum oxide film containing triethylaluminum for use in spray application (solution C).

Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

Using the obtained solution for producing an aluminum oxide film (solution C), the same operation as in Example 3-1-1 was performed to form an aluminum oxide film by spray deposition. By the same analysis of the film formed on the substrate, the formation of an aluminum oxide film at a low temperature of 200°C was confirmed by the film deposition method using this solution. The film thickness of the aluminum oxide film formed on the glass substrate was 358 nm. In addition, the transmittance in visible light (550 nm) was 95.3%, and a transparent aluminum oxide film having a transmittance of 80% or more was obtained.

[Example 3-1-4]

In Example 3-1-1, instead of tetrahydrofuran (THF), 82.7 g of diisopropyl ether was used, and 9.2 g of triethylaluminum (manufactured by Tosoh Finechem Co., Ltd.) was used, and the same operation as in Example 3-1-1 was performed to obtain a solution (solution D) for producing an aluminum oxide film containing triethylaluminum for use in spray application.

Using the obtained solution for producing an aluminum oxide film (solution D), the same operation as in Example 3-1-1 was performed to form an aluminum oxide film by spray deposition. By the same analysis of the film formed on the substrate, the formation of an aluminum oxide film at a low temperature of 200°C was confirmed by the film deposition method using this solution. The film thickness of the aluminum oxide film formed on the glass substrate was 307 nm. In addition, the transmittance in visible light (550 nm) was 97.6%, and a transparent aluminum oxide film having a transmittance of 80% or more was obtained.

[Example 3-1-5]

In Example 3-1-1, instead of tetrahydrofuran (THF), a mixed solvent of 41.3 g of tetrahydrofuran (THF) and 41.3 g of hexane was used, and triethylaluminum (manufactured by Tosoh Finechem Co., Ltd.) was changed to 9.2 g, and the same operation as in Example 3-1-1 was performed to obtain a solution for producing an aluminum oxide film containing triethylaluminum for use in spray application (solution E).

Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

Using the obtained solution for producing an aluminum oxide film (solution E), the same operation as in Example 3-1-1 was performed to form an aluminum oxide film by spray deposition. By the same analysis of the film formed on the substrate, the formation of an aluminum oxide film at a low temperature of 200°C was confirmed by the film deposition method using this solution. The film thickness of the aluminum oxide film formed on the glass substrate was 211 nm. In addition, the transmittance in visible light (550 nm) was 97.6%, and a transparent aluminum oxide film having a transmittance of 80% or more was obtained.

[Example 3-1-6]

In Example 3-1-1, instead of tetrahydrofuran (THF), a mixed solvent of 21.9 g of tetrahydrofuran (THF) and 51.0 g of toluene was used, and 8.1 g of triethylaluminum (manufactured by Tosoh Finechem Co., Ltd.) was used, and the same operation as in Example 3-1-1 was performed to obtain a solution for producing an aluminum oxide film containing triethylaluminum for use in spray application (solution F).

Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

Using the obtained solution for producing an aluminum oxide film (solution F), the same operation as in Example 3-1-1 was performed to form an aluminum oxide film by spray deposition. By the same analysis of the film formed on the substrate, the formation of an aluminum oxide film at a low temperature of 200°C was confirmed by the film deposition method using this solution. The film thickness of the aluminum oxide film formed on the glass substrate was 271 nm. In addition, the transmittance in visible light (550 nm) was 95.5%, and a transparent aluminum oxide film having a transmittance of 80% or more was obtained.

[Example 3-1-7]

In Example 3-1-4, instead of diisopropyl ether, a mixed solvent of 41.2 g of diisopropyl ether and 41.2 g of mixed xylene was used, and triethyl aluminum (manufactured by Tosoh Finechem Co., Ltd.) was changed to 9.1 g, and the same operation as Example 3-1-4 was performed to obtain a solution (solution G) for producing an aluminum oxide film containing triethyl aluminum for use in spray application.

Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

Using the obtained solution for producing an aluminum oxide film (solution G), the same operation as in Example 3-1-1 was performed to form an aluminum oxide film by spray deposition. By the same analysis of the film formed on the substrate, the formation of an aluminum oxide film at a low temperature of 200°C was confirmed by the film deposition method using this solution. The film thickness of the aluminum oxide film formed on the glass substrate was 330 nm. In addition, the transmittance in visible light (550 nm) was 93.9%, and a transparent aluminum oxide film having a transmittance of 80% or more was obtained.

[Example 3-1-8]

In Example 3-1-3, instead of 1,2-diethoxyethane, a mixed solvent of 62.3 g of 1,2-diethoxyethane and 15.6 g of mixed xylene was used, and triethylaluminum (manufactured by Tosoh Finechem Co., Ltd.) was changed to 8.7 g, and the same operation as Example 3-1-3 was performed to obtain a solution (solution H) for producing an aluminum oxide film containing triethylaluminum for use in spray application.

Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

Using the obtained solution for producing an aluminum oxide film (solution H), the same operation as in Example 3-1-1 was performed to form an aluminum oxide film by spray deposition. By the same analysis of the film formed on the substrate, the formation of an aluminum oxide film at a low temperature of 200°C was confirmed by the film deposition method using this solution. The film thickness of the aluminum oxide film formed on the glass substrate was 281 nm. In addition, the transmittance in visible light (550 nm) was 94.4%, and a transparent aluminum oxide film having a transmittance of 80% or more was obtained.

[Example 3-1-9]

In Example 3-1-8, instead of the mixed solvent of 1,2-diethoxyethane and mixed xylene, a mixed solvent of 39.5 g of 1,2-diethoxyethane and 39.5 g of toluene was used, and triethylaluminum (manufactured by Tosoh Finechem Co., Ltd.) was changed to 8.9 g, and the same operation as in Example 3-1-8 was performed to obtain a solution for producing an aluminum oxide film containing triethylaluminum for use in spray application (solution I).

Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

Using the obtained solution for producing an aluminum oxide film (solution I), the same operation as in Example 3-1-1 was performed to form an aluminum oxide film by spray film formation. By the same analysis of the film formed on the substrate, the formation of an aluminum oxide film at a low temperature of 200°C was confirmed by the film formation method using this solution. The film thickness of the aluminum oxide film formed on the glass substrate was 310 nm. In addition, the transmittance in visible light (550 nm) was 94.3%, and a transparent aluminum oxide film having a transmittance of 80% or more was obtained.

[Example 3-1-10]

In Example 3-1-1, instead of a glass substrate (EagleXG (registered trademark) manufactured by Corning Inc., 18 mm square) (thickness 0.7 mm), a polyethylene terephthalate (PET) film (60 mm square (thickness 75 μm)) was used as the substrate for forming an aluminum oxide film. The heating temperature of the substrate was changed from 200°C to 130°C, and the same operation as in Example 3-1-1 was performed. Using a solution having the same composition as the solution for producing an aluminum oxide film (solution A), an aluminum oxide film was formed on the polyethylene terephthalate (PET) film heated to 130°C by spray formation. By the same analysis of the film formed on the substrate, it was confirmed that an aluminum oxide film was formed on the polyethylene terephthalate (PET) film at a low temperature of 130°C by the film formation method using this solution. The results of SEM measurement on the surface structure of the obtained film are shown in Fig. 3d. The transmittance of this aluminum oxide film in visible light (550 nm) is 86%, and a transparent aluminum oxide film with a transmittance of 80% or more was obtained.

[Example 3-1-11]

In Example 3-1-10, instead of a polyethylene terephthalate (PET) film (60 mm square (25 μm thick)) as a substrate for forming an aluminum oxide film, a porous polypropylene (PP) film (for secondary battery separator: 60 mm square (20 μm thick)) was used, the film was heated to 130°C, and using a solution having the same composition as the solution for producing an aluminum oxide film (solution A), the same operation as in Example 3-1-10 was performed to form an aluminum oxide film by spray formation. By a similar analysis of the film formed on the substrate, it was confirmed that an aluminum oxide film was formed on the polypropylene (PP) porous film at a low temperature of 130°C by the film formation method using this solution.

[Example 3-1-12]

In Example 3-1-10, instead of a polyethylene terephthalate (PET) film (60 mm square (75 μm thick)) as a substrate for forming an aluminum oxide film, an aramid nonwoven fabric (secondary battery separator specification: 60 mm square (57 μm thick)) was used, the film was heated to 130°C, and a solution having the same composition as the solution for producing an aluminum oxide film (solution A) was used, and the same operation as in Example 3-1-10 was performed to form an aluminum oxide film by spraying.

By a similar analysis of the film formed on the substrate, it was confirmed that an aluminum oxide film was formed on an aramid porous film at a low temperature of 130°C by a film-forming method using the present solution.

[Example 3-1-13]

To 150.0 g of tetrahydrofuran (THF), 15.0 g of triethylaluminum (manufactured by Tosoh Finechem Co., Ltd.) was added at room temperature. After sufficient stirring, the solution was filtered through a filter (pore size: 3 μm or less), thereby obtaining a solution (solution J) for producing an aluminum oxide film containing triethylaluminum for use in spray coating.

Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

As a substrate for forming an aluminum oxide film, a polypropylene (PP) film (30 mm square (0.2 mm thick)) was used, the film was heated to 130°C, and an aluminum oxide film was formed by spray deposition in the same manner as in Example 3-1-1 using a solution for producing an aluminum oxide film (solution J). By a similar analysis of the film formed on the substrate, it was confirmed that an aluminum oxide film was formed on the polypropylene (PP) film at a low temperature of 130°C by the film deposition method using this solution.

[Example 3-1-14]

A solution for producing an aluminum oxide film (solution K) consisting of 69.7 g of tetrahydrofuran (THF) and 2.16 g of triethylaluminum (manufactured by Tosoh Finechem Co., Ltd.) with a reduced triethylaluminum content and a solution for producing an aluminum oxide film (solution L) consisting of 69.7 g of tetrahydrofuran (THF) and 0.70 g of triethylaluminum (manufactured by Tosoh Finechem Co., Ltd.) with a reduced triethylaluminum content were prepared by the same method as in Example 3-1-1, and film formation was performed under the conditions described in Example 3-1-1 at a heating temperature of a glass substrate of 200°C. The formation of an aluminum oxide film at 200°C was confirmed.

In addition, the aluminum oxide film obtained in this example was confirmed to be in an amorphous state because no peak was confirmed by XRD. The transmittance and film thickness in visible light (550 nm) of the aluminum oxide film obtained by spray film formation using each of solution K and solution L were 99% and 75 nm (solution K) and 99% and 30 nm (solution L), respectively.

[Example 3-1-15]

In Examples 3-1-1 and 3-1-2, the heating temperature of the glass substrate was changed to 300°C using the aluminum oxide film manufacturing solution obtained in each example (Solution A: Example 3-1-1, Solution B: Example 3-1-2), the same operation was performed, and the formation of an aluminum oxide film at 300°C was confirmed by the same analysis using the film forming method using the present solution. The aluminum oxide film obtained in this example was confirmed to be in an amorphous state since no peak was confirmed by XRD.

[Example 3-1-16]

The adhesion of the films obtained in Examples 3-1-1 to 10 was confirmed by a peeling test using Scotch Tape (registered trademark) 2364 (3M product). The tape was firmly pressed and attached to the film-forming surface of the polypropylene (PP) film on which an aluminum oxide film was formed, and then peeled off at an angle of 45°. After peeling, the film was visually checked by ATR-IR and SEM measurements, and no strong peeling of the film was confirmed, confirming that the film formed using the present composition had high adhesion.

[Example 3-1-17]

As a substrate for forming an aluminum oxide film, paper (about a bag (square 20 mm (thickness 31 µm)) was used, the paper was heated to 142°C, and an aluminum oxide film-making solution (solution D) prepared in Example 3-1-4 was used, and the same operation as in Example 3-1-1 was performed to form an aluminum oxide film by spray formation. By the same analysis of the film formed on the paper, it was confirmed that an aluminum oxide film was formed on the paper at a low temperature of 142°C by the film-forming method using this solution.

The obtained film was analyzed by SEM, and Fig. 3e was obtained, confirming that the surface of the paper fibers was coated with aluminum oxide in the form of particles.

[Example 3-1-18]

Any of the substrates to which the aluminum oxide films obtained in Examples 3-1-1 to 10 and 14 were attached had a high vertical transmittance of 80% or higher at 550 nm, and thus could be used as optical materials. In addition, the aluminum oxide films formed on glass substrates showed no deterioration even when heated at 500°C, and thus could be used as heat-resistant materials. When the surface resistances of the films obtained in Examples 3-1-1 to 15 and 17 were measured, no resistance values were obtained, indicating that they had no conductivity, and thus could be used as insulating materials. It was confirmed that the substrates to which the aluminum oxide films of Examples 3-1-1, 10 and 17 were attached had fine unevenness on the surface of the films obtained by the deposition, and thus could have an antireflection effect and could be used as catalyst carriers. In Examples 3-1-1 to 10 and 17, the aluminum oxide film formed using the composition of the present invention has high adhesion to substrates such as glass or resin, and therefore can be used as a protective film for various substrates, a base for a coating or a laminated film, an undercoat film, a film for electronic devices that can be laminated onto a substrate, and the like. In this way, the substrate to which the aluminum oxide film of the present invention is attached can be used as an aluminum oxide functional film.

[Example 3-1-19]

The glass substrate having the aluminum oxide film described in Examples 3-1-1 to 9, 14 and 15, the plate and film of a resin such as polypropylene (PP), polyethylene terephthalate (PET) or acrylic having the aluminum oxide film obtained in Examples 10 to 13, and the paper having the aluminum oxide film obtained in Example 3-1-17 can all be used as a substrate having an aluminum oxide functional film having the function described in Example 3-1-18.

[Comparative Example 3-1-1]

In Example 3-1-2, hexane was used instead of tetrahydrofuran (THF), and the same operation as in Example 3-1-2 was performed to obtain a solution (solution X) for producing an aluminum oxide film containing triethylaluminum for use in spray application.

Using a solution (solution K) that does not contain this electron-donating solvent, the same operation as in Example 3-1-1 was performed to form an aluminum oxide film by spray deposition, but only a powdery substance was attached to the substrate. In addition, almost no powdery substance was attached and was peeled off from the substrate, so that an aluminum oxide film was not formed.

[Comparative Example 3-1-2]

In Example 3-1-1, in a nitrogen atmosphere containing 0.003 mol% of moisture (0.1% relative humidity at 21°C) in an inert gas at atmospheric pressure and substantially mostly free of moisture, solution A was sprayed from a spray nozzle at 2 mL/min for 8 minutes onto a substrate heated with a heater. The same operation as in Example 3-1-1 was performed to form an aluminum oxide film by spray film formation, but almost no matter adhered to the substrate, and after completion of film formation, the obtained film was heated at 200°C in a nitrogen atmosphere containing moisture at a relative humidity of 90%, but almost no matter adhered to the substrate, and therefore, likewise, the formation of an aluminum oxide film could not be confirmed.

[Comparative Example 3-1-3]

To 86.41 g of toluene, 4.32 g of aluminum trisacetylacetonate (Al(acac) ₃ ) was added at room temperature. After sufficient stirring, the solution was filtered through a filter (pore size: 3 μm or less), thereby obtaining a solution (solution L) for producing an aluminum oxide film containing aluminum trisacetylacetonate (Al(acac) ₃ ) for use in spray coating.

Using a solution (solution Y) containing an organoaluminum compound that does not include a straight-chain or branched alkyl group having 1 to 3 carbon atoms in its structure, an aluminum oxide film was formed by spray film formation in the same manner as in Example 3-1-1.

Using a solution (solution L) that does not contain this electron-donating solvent, the same operation as in Example 3-1-1 was performed, and a film was formed by spray deposition at a substrate heating temperature of 200°C. However, almost no attachment to the substrate occurred, and an aluminum oxide film was not formed.

[Comparative Example 3-1-4]

To 90.19 g of toluene, 4.51 g of aluminum triisopropoxide (Al(O ⁱ Pr) ₃ ) was added at room temperature. After sufficient stirring, the solution was filtered through a filter (pore size: 3 μm or less), thereby obtaining a solution (solution Z) for producing an aluminum oxide film containing aluminum triisopropoxide (Al(O ⁱ Pr) ₃ ) for use in spray coating.

Using a solution (solution M) containing an organoaluminum compound that does not include a straight-chain or branched alkyl group having 1 to 3 carbon atoms in its structure, the same operation as in Example 3-1-1 was performed, and a film was formed by spray deposition at a substrate heating temperature of 200°C. However, almost no attachment to the substrate occurred, and an aluminum oxide film was not formed.

[Example 3-2-1]

To 108.45 g of tetrahydrofuran (THF) was added 15.13 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) at room temperature. To the TEAL/THF solution obtained by sufficient stirring, 48.8 g of a THF solution containing 0.48 g of water was added dropwise while stirring so that the temperature became around 20°C while removing the exotherm caused by the reaction so that the molar ratio of water to TEAL (water/TEAL) became 0.2. Thereafter, the solution was heated to 65°C and reacted at 65°C for 2.5 hours. After completion of the reaction, the solution was allowed to cool and the reaction product was recovered. The product after the reaction was a colorless transparent solution. Regarding the reactivity of the chemical solution, when the reactivity on a filter paper was visually confirmed, no pressing of the filter paper, etc., was observed.

In this way, a composition for producing an aluminum oxide film (composition A) containing a product obtained by partially hydrolyzing triethylaluminum was obtained.

Using this composition A, an aluminum oxide film was formed by the spray pyrolysis method. As a substrate for forming an aluminum oxide film, a glass substrate (Corning Corporation, EagleXG (registered trademark)) measuring 18 mm on each side (thickness 0.7 mm) was used. The glass substrate was heated to 200°C, and in a nitrogen atmosphere containing 2.3 mol% of water (90% relative humidity at 21°C) in an inert gas at atmospheric pressure, solution A was sprayed from a spray nozzle at 2 mL/min for 8 minutes onto the substrate heated with a heater. The molar ratio of water, which was the oxygen source supplied during this film formation, to the molar number of Al in the composition A was 90. The size of the droplets discharged from the spray nozzle was in the range of 3 to 20 μm, and the distance between the spray nozzle and the substrate was set to 20 cm. After completion of spraying, the substrate on which the film was formed was continuously heated for 5 minutes.

The film formed on the glass substrate was taken out into the air after cooling, and analyzed by SEM and EPMA, and it was confirmed that the adhesion of the film and the elements constituting the film were oxygen and aluminum elements. Fig. 3g shows the results of SEM analysis of the surface of the film obtained in this example, and Fig. 3h shows the results of SEM analysis of the cross-section of the film, respectively. In addition, when analyzed by ATR-IR, it was confirmed that an increase in the peak overlapping with the peak derived from the glass substrate in the vicinity of 550 to 1000 cm ^-1 and a peak attributed to CH which the organic aluminum compound or solvent has in its structure, which appears between 2800 and 3100 cm ^-1 , were not observed. From the above analysis, it was confirmed that an aluminum oxide film was formed at a low temperature of 200°C by the film-forming method using this solution. In addition, the aluminum oxide film obtained in this example had no peak confirmed by XRD, confirming that it was in an amorphous state. The film thickness of the aluminum oxide film was 146 nm as measured by a stylus-type surface profile measuring instrument. In addition, the transmittance in visible light (550 nm) was 91.0%, and a transparent aluminum oxide film with a transmittance of 80% or more was obtained.

Regarding the adhesion of the obtained film, a cross-cut test and a peeling test using Scotch tape (registered trademark) 2364 (3M product) used in the cross-cut test were performed, and it was confirmed by visual inspection and ATR-IR and SEM measurements that there was no peeling of the film.

[Example 3-2-2]

In Example 3-2-1, 0.95 g of water was used instead of 0.48 g of water, and the molar ratio of water to TEAL (water/TEAL) was 0.4, so that the solution was added dropwise, and a colorless transparent solution was obtained using the same method as Example 3-2-1. Regarding the reactivity of the drug solution, the reactivity on a filter paper was visually confirmed, and no pressing of the filter paper, etc., was observed.

In this way, a composition for producing an aluminum oxide film (composition B) containing a product obtained by partially hydrolyzing triethylaluminum was obtained. Using this composition B, an aluminum oxide film was formed by a spray pyrolysis method in the same manner as in Example 3-2-1. Through the same analysis as in Example 3-2-1, it was confirmed that an aluminum oxide film was formed at a low temperature of 200°C by a film-forming method using composition B. In addition, the aluminum oxide film obtained in this example was confirmed to be in an amorphous state since no peak was confirmed by XRD. The film thickness of the aluminum oxide film was measured by a stylus-type surface profile measuring device and was 119 nm. In addition, the transmittance in visible light (550 nm) was 84.3%, and a transparent aluminum oxide film having a transmittance of 80% or more was obtained.

Regarding the adhesion of the obtained film, a crosscut test and a peeling test using Scotch tape (registered trademark) 2364 (3M product) used in the crosscut test were performed in the same manner as in Example 3-2-1, and it was confirmed by visual inspection, ATR-IR, and SEM measurements that there was no peeling of the film. Fig. 3i shows the results of SEM analysis of the surface of the film obtained in this example, and Fig. 3j shows the results of SEM analysis of a cross-section of the same film.

[Example 3-2-3]

In Example 3-2-1, 1.44 g of water was used instead of 0.48 g of water, and the molar ratio of water to TEAL (water/TEAL) was added dropwise so that 0.6 was obtained, using the same method as Example 3-2-1, to obtain a colorless transparent solution. A trace amount of gel-shaped insoluble matter contained in the product was filtered through a filter (pore size: 3 ㎛ or less), and the colorless transparent solution was recovered. Regarding the reactivity of the chemical solution, the reactivity on filter paper was visually confirmed, and no pressing of the filter paper, etc. was observed.

In this way, a composition for producing an aluminum oxide film (composition C) containing a product obtained by partially hydrolyzing triethylaluminum was obtained. Using this composition C, an aluminum oxide film was formed by a spray pyrolysis method in the same manner as in Example 3-2-1. Through the same analysis as in Example 3-2-1, it was confirmed that an aluminum oxide film was formed at a low temperature of 200°C by a film-forming method using composition C. In addition, the aluminum oxide film obtained in this example was confirmed to be in an amorphous state since no peak was confirmed by XRD. The film thickness of the aluminum oxide film was 76 nm as measured by a stylus-type surface profile measuring device. In addition, the transmittance in visible light (550 nm) was 83.3%, and a transparent aluminum oxide film having a transmittance of 80% or more was obtained.

Regarding the adhesion of the obtained film, a cross-cut test and a peeling test using Scotch tape (registered trademark) 2364 (3M product) used in the cross-cut test were performed in the same manner as in Example 3-2-1, and it was confirmed by visual inspection and ATR-IR and SEM measurements that there was no peeling of the film.

[Comparative Example 3-2-1]

In Example 3-2-1, 1.91 g of water was used instead of 0.48 g of water, and the molar ratio of water to TEAL (water/TEAL) was set to 0.8. A colorless transparent solution was obtained using the same method as in Example 3-2-1. A trace amount of gel-like insoluble matter contained in the product was filtered through a filter (pore size: 3 ㎛ or less), and the colorless transparent solution was recovered. Regarding the reactivity of the chemical solution, the reactivity on filter paper was visually confirmed, and no pressing of the filter paper, etc., was observed.

In this way, a composition for producing an aluminum oxide film (composition D) containing a product obtained by partially hydrolyzing triethylaluminum was obtained. Using this composition D, an aluminum oxide film was formed by a spray pyrolysis method in the same manner as in Example 3-2-1, but almost no attachment to the substrate was observed, and it was not possible to form a film.

[Comparative Example 3-2-2]

In Example 3-2-1, except that the amount of water added during hydrolysis was changed so that the molar ratio of water to TEAL (water/TEAL) became 1.0, the same method as for preparing Composition A in Example 3-2-1 was used to prepare a composition for producing an aluminum oxide film (Composition E) containing a product obtained by partially hydrolyzing triethylaluminum. Using this Composition E, an aluminum oxide film was formed at 200°C by a spray pyrolysis method in the same manner as in Example 3-2-1, but a white powder attached to the substrate surface, and a film having good adhesion could not be obtained.

Regarding the adhesion of the obtained film, a crosscut test and a peeling test using Scotch tape (registered trademark) 2364 (3M product) used in the crosscut test were performed in the same manner as in Example 3-2-1, and it was confirmed by visual and ATR-IR and SEM measurements that the white powder attached to the substrate surface was peeled off. The results of spray film formation using each composition prepared in Examples 3-2-1, 2, 3, and 4 and Comparative Example 3-2-1 are shown in Table 3-1.

[Example 3-2-4]

To 73.2 g of tetrahydrofuran (THF) was added 11.35 g of triethylaluminum (TEAL: manufactured by Tosoh Finechem Co., Ltd.) at room temperature. To the TEAL/THF solution obtained by sufficient stirring, while cooling the exotherm caused by the reaction to around 20°C, 36.6 g of a THF solution containing 1.08 g of water was added dropwise while stirring so that the molar ratio of water to TEAL (water/TEAL) became 0.6. Thereafter, the solution was heated to 65°C and reacted at 65°C for 2.5 hours. After completion of the reaction, the solution was allowed to cool and the reaction product was recovered. The product after the reaction was a colorless transparent solution. A trace amount of gel-like insoluble matter contained in the product was filtered through a filter (pore size: 3 μm or less) to recover a colorless transparent solution. Regarding the reactivity of the solution, the reactivity on the filter paper was visually confirmed, and no pressing of the filter paper was observed.

In this way, a composition for producing an aluminum oxide film (composition F) containing a product obtained by partially hydrolyzing triethylaluminum was obtained. For a part of this composition F, after removing the solvent, etc. by vacuum drying, the residue mainly containing the product obtained by partially hydrolyzing triethylaluminum was subjected to ¹ H-NMR (THF-d ₈ , ppm) measurement, and the spectrum of Fig. 3f was obtained. Using this composition F, an aluminum oxide film was formed by a spray pyrolysis method in the same manner as in Example 3-2-1. By the same analysis as in Example 3-2-1, the formation of an aluminum oxide film at a low temperature of 200°C was confirmed by the film-forming method using composition F.

[Example 3-2-5]

Using the composition A prepared in Example 3-2-1, a polypropylene (PP) film (30 mm square (0.2 mm thick)) and a polyethylene terephthalate (PET) film (60 mm square (75 μm thick)) were used as substrates for forming an aluminum oxide film, and an aluminum oxide film was formed on each substrate by a spray pyrolysis method using the same method as in Example 3-2-1 at a heating temperature of 130°C. Through the same analysis as in Example 3-2-1, it was confirmed that an aluminum oxide film was formed at a low temperature of 130°C by the film-forming method using composition F.

[Comparative Example 3-2-3]

In Example 3-2-1, an aluminum oxide film was formed by spray pyrolysis using the same method as in Example 3-2-1, except that a nitrogen atmosphere containing 0.25 mol% of water (1% relative humidity at 21°C) of water in the inert gas was created using a composition for producing an aluminum oxide film (composition A) containing a product obtained by partially hydrolyzing triethylaluminum. In this film formation, almost no attachment to the glass substrate occurred, and thus an aluminum oxide film could not be obtained.

[Example 3-2-6]

Any of the substrates to which the aluminum oxide films obtained in Examples 3-2-1, 2, and 3 are attached have a vertical transmittance of 80% or higher at 550 nm, and can be used as optical materials. In addition, the aluminum oxide films formed on glass substrates show no change even when heated at 500°C after film formation, and can be used as heat-resistant materials. When the surface resistance of these films was measured, no resistance was obtained, and thus there was no conductivity, and thus they can be used as insulating materials. In addition, the aluminum oxide films formed using the composition of the present invention have high adhesion to substrates such as glass or resin, and therefore can be used as protective films for various substrates, as bases for coatings or laminated films, as undercoat films, and as films for electronic devices that can be laminated on substrates. It was confirmed that these substrates to which the aluminum oxide films are attached have minute unevenness on the surface of the film obtained by film formation, and thus they can be used as antireflection effects and catalyst carriers. In this way, the substrates to which the aluminum oxide films of the present invention are attached can be used as aluminum oxide functional films.

[Example 3-2-8]

The glass substrate having the aluminum oxide film described in Examples 3-2-1, 2, 3 and 4, or the resin film such as polypropylene (PP) or polyethylene terephthalate (PET) having the aluminum oxide film obtained in Example 3-2-6 can all be used as a substrate having the aluminum oxide functional film having the function described in Example 3-2-7.

<Fourth aspect of the present invention>

The preparation of the solution containing the alkyl aluminum compound of the present invention was carried out under a nitrogen gas atmosphere, and all solvents were used after being dehydrated and degassed.

<Number of moles of trialkyl aluminum>

It is the same as the first aspect of the present invention.

<Measurement of physical properties>

The average particle diameter (50% volume diameter) of droplets formed using the spray nozzle of the present invention was measured at a distance of 20 cm from the spray nozzle using a laser light scattering type particle size distribution measuring device (“Spray particle diameter distribution measuring device CT Aerotruck LDSA-3500A” manufactured by Nikkiso Co., Ltd.).

The aluminum oxide thin film produced by the manufacturing method of the present invention was subjected to relative IR measurement by the ATR (Attenuated Total Reflection) method using a ZnSe prism in an FT-IR spectrometer ("FT/IR-4100" manufactured by Nippon Bunko Co., Ltd.) without ATR correction.

Originally, when using a ZnSe prism, it was difficult to measure a thin film having a refractive index exceeding 1.7, and considering that the refractive index of general aluminum oxide is 1.77, it was assumed that measurement would be difficult. However, surprisingly, measurement was possible. It was estimated that the refractive index of the aluminum oxide thin film according to the present invention is 1.7 or less.

The aluminum oxide thin film produced by the manufacturing method of the present invention was cut out of a portion of the film with a knife, and the film thickness was measured using a stylus-type surface shape measuring device (DektakXT-S, manufactured by Bulganano Corporation).

The aluminum oxide thin film produced by the manufacturing method of the present invention was subjected to vertical visible light transmittance measurement using a light source (DH-2000-BAL, manufactured by Ocean Photonics) and a spectrometer (USB-4000, manufactured by Ocean Photonics).

[Example 4-1]

2.01 g of triethylaluminum (product of Tosoh Finechem) was added to 18.0 g of tetrahydrofuran (hereinafter referred to as THF) at 25°C and stirred sufficiently to obtain a 10 mass% triethylaluminum THF solution (hereinafter referred to as Solution A).

Spray application was performed using the obtained solution A. The application was performed in air at room temperature 25°C and a relative humidity of 43%, using a two-fluid spray nozzle (ultra-small vortex precision spray nozzle, manufactured by Atomax, AM4S-OSV-0.4, nozzle diameter 0.4 mm). The distance between the spray nozzle and the substrate (alkali-free glass, manufactured by Corning, EagleXG, 18 mm×18 mm×0.7 mmt) was 20 cm. Droplets of 3 to 30 μm were formed by mixing 2 ml/min of solution A and 8 NL/min of nitrogen gas at the spray nozzle. The average particle diameter (50% volume diameter) of the formed droplets was 8.5 μm as measured by a laser light scattering type particle size distribution measuring device. The formed droplets were sprayed on a substrate heated to 200°C for 8 minutes.

When the thin film formed on the substrate was subjected to IR measurement by the ATR method, a spectrum as in Fig. 4b was obtained. A broad Al-O-Al vibration peak was confirmed around 550 to 1500 cm ^-1 , confirming the formation of an Al-O-Al bond. Therefore, the formation of an aluminum oxide thin film was confirmed. Since there was no vibration peak of an organic substance around 3000 cm ^-1 , it was confirmed that there was no residual organic substance. The IR spectrum of the alkali-free glass itself by the ATR method is Fig. 4a, which is clearly different from Fig. 4b. The vertical transmittance at visible light 550 nm was 97.5%, indicating transparency, and the film thickness was 293 nm according to a stylus-type surface shape measuring device.

[Example 4-2]

Triethyl aluminum (manufactured by Tosoh Finechem) (2.00 g) was added to 18.01 g of diisopropyl ether at 25°C and stirred sufficiently to obtain a 10 mass% triethyl aluminum diisopropyl ether solution (hereinafter referred to as Solution B).

Except for using solution B, the same method and conditions as in Example 4-1 were applied by spraying to the same substrate as in Example 4-1. The average particle diameter (50% volume diameter) of the formed droplets was measured using a laser light scattering type particle size distribution measuring device, and was 8.0 μm.

When the thin film formed on the substrate was subjected to IR measurement by the ATR method, a spectrum as in Fig. 4c was obtained. As in Example 4-1, the formation of Al-O-Al bonds was confirmed. Therefore, the formation of an aluminum oxide thin film was confirmed. Since there was no vibration peak of organic substances near 3000 cm ^-1 , it was confirmed that there was no residual organic substance. The vertical transmittance at visible light 550 nm was 98.0%, which was transparent, and the film thickness was 277 nm according to a stylus-type surface shape measuring device.

[Example 4-3]

At 25°C, 10.01 g of hexane and 2.01 g of triethylaluminum (manufactured by Tosoh Finechem) were added to 8.00 g of THF, and stirred sufficiently to obtain a 10 mass% triethylaluminum diisopropyl ether solution (hereinafter referred to as Solution C).

Except for using solution C, the same method and conditions as in Example 4-1 were applied by spraying to the same substrate as in Example 4-1. The average particle diameter (50% volume diameter) of the formed droplets was measured using a laser light scattering type particle size distribution measuring device and was 7.5 μm.

When the thin film formed on the substrate was measured by IR using the ATR method, the formation of Al-O-Al bonds was confirmed, as in Example 4-1. Therefore, the formation of an aluminum oxide thin film was confirmed.

[Example 4-4]

2.01 g of triisobutyl aluminum (product of Tosoh Finechem) was added to 17.9 g of tetrahydrofuran (hereinafter referred to as THF) at 25°C and stirred sufficiently to obtain a 10 mass% triisobutyl aluminum THF solution (hereinafter referred to as Solution D).

Except for using solution D, the same method and conditions as in Example 4-1 were applied by spraying to the same substrate as in Example 4-1. The average particle diameter (50% volume diameter) of the formed droplets was measured using a laser light scattering type particle size distribution measuring device, and was 8.0 μm.

When the thin film formed on the substrate was subjected to IR measurement by the ATR method, a spectrum as in Fig. 4d was obtained. As in Example 4-1, the formation of Al-O-Al bonds was confirmed. Therefore, the formation of an aluminum oxide thin film was confirmed. Since there was no vibration peak of organic substances near 3000 cm ^-1 , it was confirmed that there were no residual organic substances. The vertical transmittance at visible light 550 nm was 99.3%, which was transparent, and the film thickness was 130 nm according to a stylus-type surface shape measuring device.

[Comparative Example 4-1]

2.00 g of triethyl aluminum (manufactured by Tosoh Finechem) was added to 18.00 g of hexane at 25°C and stirred sufficiently to obtain a 10 mass% triethyl aluminum hexane solution (hereinafter referred to as Solution E).

Except for using solution E, the same method and conditions as in Example 4-1 were used to spray-coat the same substrate as in Example 4-1. From the IR measurement by the ATR method, the vertical transmittance measurement, and the stylus surface shape measurement, it was found that no thin film was formed and thus the thin film was not attached.

[Comparative Example 4-2]

1.01 g of aluminum isopropoxide (Aldrich product) was added to 19.1 g of toluene at 25°C and stirred sufficiently to obtain a 5 mass% aluminum isopropoxide toluene solution (hereinafter referred to as solution F).

Except for using solution F, the same method and conditions as in Example 4-1 were used to spray-coat the same substrate as in Example 4-1. From the IR measurement by the ATR method, the vertical transmittance measurement, and the stylus surface shape measurement, it was found that no thin film was formed and thus the thin film was not attached.

[Comparative Example 4-3]

1.00 g of aluminum acetylacetonate (Aldrich product) was added to 19.0 g of toluene at 25°C and stirred sufficiently to obtain a 5 mass% aluminum acetylacetonate toluene solution (hereinafter referred to as Solution G).

Except for using solution G, the same method and conditions as in Example 4-1 were used to spray-coat the same substrate as in Example 4-1. From the IR measurement by the ATR method, the vertical transmittance measurement, and the stylus surface shape measurement, no thin film was formed, and thus, the thin film was not attached.

<Fifth aspect of the present invention>

The preparation of the solution containing the alkyl aluminum compound of the present invention was carried out under a nitrogen gas atmosphere, and all solvents were used after being dehydrated and degassed.

<Number of moles of trialkyl aluminum>

It is the same as the first aspect of the present invention.

<Measurement of physical properties>

The average particle diameter (50% volume diameter) of droplets formed using the spray nozzle of the present invention was measured at a distance of 20 cm from the spray nozzle using a laser light scattering type particle size distribution measuring device ("Spray particle diameter distribution measuring device CT Aerotrack LDSA-3500A" manufactured by Nikkiso Co., Ltd.).

The film thickness and refractive index of the aluminum oxide thin film produced by the manufacturing method of the present invention were measured using a high-speed spectroscopic ellipsometer (M-2000, manufactured by J.A.Uram Japan).

The effective carrier lifetime was measured using a lime time measuring device (WCT-120, Sinton) by the pseudo-steady-state photoconductivity method (QSSPC method). In addition, the effective carrier lifetime in the examples is the value when the excess carrier density is 10 ¹⁵ cm ^-3 .

Using the effective carrier lifetime value measured as above, the surface recombination velocity S was obtained according to the following equation (1). In equation (1), W represents the wafer thickness, τ _eff represents the effective lifetime, and τ _bulk represents the bulk lifetime. W was calculated as 300 μm, and τ _bulk was calculated as ∞.

[Example 5-1]

2.01 g of triethylaluminum (product of Tosoh Finechem) was added to 18.1 g of tetrahydrofuran (hereinafter referred to as THF) at 25°C and stirred sufficiently to obtain a 10 mass% triethylaluminum THF solution (hereinafter referred to as Solution A).

Spray application was performed using the obtained solution A. In a nitrogen gas atmosphere, the application was performed using a two-fluid spray nozzle (ultra-small vortex precision spray nozzle, manufactured by Atomax, AM4S-OSV-0.4, nozzle diameter: 0.4 mm). The distance between the spray nozzle and the substrate (p-type silicon substrate, manufactured by Topsil, PV-FZ (wafer thickness 255 to 305 ㎛, orientation <100>, volume resistivity 1 to 5 Ωcm), 4-inch disc divided into four equal parts, used after cleaning with 5 wt% hydrofluoric acid) was 20 cm. By mixing 2 mL/min of solution A and 8 NL/min of nitrogen gas in the spray nozzle, droplets having an average particle diameter of 3 to 30 ㎛ were formed. The average particle diameter (50% volume diameter) of the formed droplets was measured by a laser light scattering type particle size distribution measuring device, and it was 8.5 ㎛. At the same time, nitrogen gas containing moisture formed by introducing 10 NL/min of nitrogen gas into water heated to 65°C was introduced near the substrate. The formed droplets were sprayed on the substrate heated to 200°C for 2 minutes in the presence of the moisture. Thereafter, the substrate was completely changed to a nitrogen gas atmosphere and then fired at 400°C for 5 minutes. The same treatment was performed on the reverse side.

The film thickness and refractive index of the thin film formed on the substrate were measured using a high-speed spectroscopic ellipsometer and were 69 nm and 1.50, respectively. The effective lifetime was 606 μs and the recombination velocity was 24.8 cm/s.

[Example 5-2]

The film obtained in Example 5-1 was further fired at 400°C for 5 minutes in a forming gas atmosphere consisting of 5 vol% hydrogen and 95 vol% nitrogen. The effective lifetime of the obtained film increased to 698 μs, and the recombination velocity became 21.5 cm/s.

[Example 5-3]

2.00 g of triethyl aluminum (manufactured by Tosoh Finechem) was added to 18.1 g of diisopropyl ether at 25°C and stirred sufficiently to obtain a 10 mass% triethyl aluminum diisopropyl ether solution (hereinafter referred to as Solution B).

Except for using solution B, the same method and conditions as in Example 5-1 were used, spraying and firing the same material as in Example 5-1. The average particle diameter (50% volume diameter) of the formed droplets was measured using a laser light scattering type particle size distribution measuring device, and was 8.0 ㎛.

The effective lifetime of the thin film formed on the substrate was 506 μs, and the recombination velocity was 29.6 cm/s.

[Example 5-4]

The film obtained in Example 5-3 was further fired at 400°C for 5 minutes in a forming gas atmosphere consisting of 5 vol% hydrogen and 95 vol% nitrogen. The effective lifetime of the obtained film increased to 821 μs, and the recombination velocity became 18.3 cm/s.

The results up to this point are summarized in Table 5-1.

[Table 5-1]

The present inventions 1 to 5 are useful in the field of manufacturing aluminum oxide films. In particular, the present invention 1 is useful in the field of alkylating agents and reagents for organic synthesis, etc., and in the field of manufacturing aluminum oxide films. The aluminum oxide films can provide heat dissipation properties, heat resistance, barrier properties against air and moisture, antireflection effects, antistatic effects, antifogging effects, wear resistance, etc.

The aluminum oxide thin film of the present invention 4 can provide heat dissipation properties, heat resistance, barrier properties against air and moisture, anti-reflection effects, anti-static effects, anti-fogging effects, wear resistance, and a passive film.

The aluminum oxide thin film of the present invention 5 can be provided as a passivation film, a solar cell element using the same, etc.

Figures 2a and 3a
1: Spray bottle 2: Base holder (with heater attached)
3: Spray nozzle 4: Compressor
5: Description 6: Tube for introducing steam
Figures 5a and 5b
1: Spray bottle 2: Base holder (with heater attached)
3: Spray nozzle 4: High pressure nitrogen cylinder
5: Description 6: Water inlet
7: Inert gas inlet 8: Exhaust port
9: Fence 11: Silicon semiconductor substrate
12: n+ layer 13: anti-reflection and passive thin film
14: Passive thin film 15: Grid electrode
16: Aluminum electrode 17: Al-Si alloy layer
18: P ⁺ layer 100: Solar cell element

Claims (35)

A method for manufacturing an article having an aluminum oxide film, comprising the following processes:
(A) A process for obtaining a composition containing a partial hydrolyzate of an organoaluminum compound represented by the following general formula (6) by partially hydrolyzing the organoaluminum compound in an organic solvent, wherein the organic solvent includes an ether solvent, an amine solvent, a linear or branched hydrocarbon compound or a cyclic hydrocarbon compound having 5 to 20 carbon atoms, an aromatic hydrocarbon compound having 6 to 20 carbon atoms, or a mixture thereof, and the partial hydrolysis is performed using water having a molar ratio of 0.4 to 1.3 with respect to the organoaluminum compound,
(B) a process of forming a coating film by applying the composition containing the above-mentioned partial hydrolyzate to at least a portion of the surface of a substrate under an inert gas atmosphere;
(C) A method for manufacturing an article having an aluminum oxide film, including a step of forming an aluminum oxide film by heating a substrate having the above coating film formed at a temperature of 40 to 400°C under an inert gas atmosphere [provided that, in the case where the composition in step (A) includes a compound represented by the following general formula,


(In the formula, R ₁ , R ₂ and R ₃ represent an alkyl group or an alkenyl group, R ₄ represents an alkyl group, an alkenyl group or hydrogen, and n represents an integer from 2 to 18.) and excluding cases where the structural unit is included as indicated below,
or
(In the formula, M is a trivalent or tetravalent metal atom, Y is an organic moiety, nitro group, or halogen, m is an integer from 0 to 5, and X ₁ is
represents an organic residue, hydrogen atom, nitro group or halogen identical or different from:

(In the formula, R ¹ represents hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, and R ² and R ³ independently represent hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, a straight-chain or branched alkoxyl group having 1 to 7 carbon atoms, an acyloxy group, or an acetylacetonate group.) In the first paragraph, the inert gas atmosphere used in the processes (B) and (C) is a method for manufacturing a product having an aluminum oxide film that does not contain moisture. A method for manufacturing an article having an aluminum oxide film, wherein in the first paragraph, the application of the partially hydrolyzed product-containing composition in the step (B) is performed at a temperature in the range of 20 to 350°C.
delete A method for manufacturing an article having an aluminum oxide film, wherein the coating base material obtained in the step (B) is heated at a temperature of 20 to 200°C under an inert gas atmosphere, at least a portion of the organic solvent in the coating film is removed, and then provided to the step (C) to form an aluminum oxide film. A method for producing an article having an aluminum oxide film, wherein in the first paragraph, in the process (A), after mixing the organic aluminum compound and water, the mixture is heated to a temperature of 30 to 80°C to obtain a composition containing a partial hydrolyzate. A method for manufacturing an article having an aluminum oxide film, wherein the composition containing a partial hydrolyzate prepared in the step (A) is filtered to remove insoluble matters and then used in the step (B). In the first paragraph, the film formation in the process (B) is a method for manufacturing an article having an aluminum oxide film, which is performed by a spray coating method, an immersion coating method, a spin coating method, a slit coating method, a slot coating method, a bar coating method, a roll coating method, a curtain coating method, an electrostatic coating method, an inkjet method, or a screen printing method. A method for producing an article having an aluminum oxide film, wherein in the first paragraph, the organic solvent used for preparing a partial hydrolyzate in the step (A) is an organic solvent containing a hydrocarbon compound and/or an electron-donating solvent. A method for manufacturing an article having an aluminum oxide film, wherein the concentration of the partial hydrolyzate in the composition containing the partial hydrolyzate prepared in the process (A) in the first paragraph is in a range of 0.1 to 30 mass%. A method for producing an article having an aluminum oxide film, wherein in the first paragraph, the organic aluminum compound represented by the general formula (6) used in the process (A) is a product having an aluminum oxide film, wherein R ¹ in the formula is a methyl group or an ethyl group. A method for producing an article having an aluminum oxide film, wherein the organoaluminum compound represented by the general formula (6) used in the process (A) in claim 1 is triethylaluminum or a mixture of organoaluminum compounds containing triethylaluminum. A method for manufacturing an article having an aluminum oxide film, wherein the substrate used in the process (B) in the first paragraph is a glass substrate or a resin substrate. A composition containing a partial hydrolyzate of an organoaluminum compound obtained by partially hydrolyzing the organoaluminum compound represented by the following general formula (6) in an organic solvent, wherein the organic solvent includes an ether solvent, an amine solvent, a straight-chain, branched hydrocarbon compound or a cyclic hydrocarbon compound having 5 to 20 carbon atoms, an aromatic hydrocarbon compound having 6 to 20 carbon atoms, or a mixture thereof.
(A) The partial hydrolysis is performed using water having a molar ratio of 0.4 to 1.3 to the organoaluminum compound, and
(b) The composition is a composition containing a partial hydrolyzate of an organic aluminum compound, which is used for forming an aluminum oxide film, the film-forming process being performed under an inert gas atmosphere [provided that, in the case of containing a compound represented by the following general formula,


(In the formula, R ₁ , R ₂ and R ₃ represent an alkyl group or an alkenyl group, R ₄ represents an alkyl group, an alkenyl group or hydrogen, and n represents an integer from 2 to 18.) and excluding cases where the structural unit is included as indicated below,
or
(In the formula, M is a trivalent or tetravalent metal atom, Y is an organic moiety, nitro group, or halogen, m is an integer from 0 to 5, and X ₁ is
represents an organic residue, hydrogen atom, nitro group or halogen identical or different from:

(In the formula, R ¹ represents hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, and R ² and R ³ independently represent hydrogen, a straight-chain or branched alkyl group having 1 to 4 carbon atoms, a straight-chain or branched alkoxyl group having 1 to 7 carbon atoms, an acyloxy group, or an acetylacetonate group.) In the 14th paragraph, the film formation performed under the inert gas atmosphere is
(b1) a process of forming a coating film by applying the composition containing the above-mentioned partial hydrolyzate to at least a portion of the surface of a substrate under an inert gas atmosphere, and
(b2) A composition containing a partial hydrolyzate of an organic aluminum compound, comprising a process of forming an aluminum oxide film by heating a substrate having the above coating film formed at a temperature of 40 to 400°C under an inert gas atmosphere. A composition containing a partially hydrolyzed product of an organoaluminum compound that does not contain insoluble matter, filtered using a filter having a pore diameter of 3 ㎛ or less in claim 14. A composition containing a partial hydrolyzate of the organoaluminum compound described in claim 14, for forming a transparent aluminum oxide film in close contact with a substrate. A method as described in any one of claims 1 to 3 and claims 5 to 13,
Or an article having an aluminum oxide film, manufactured under an inert gas atmosphere using the composition described in any one of claims 14 to 17. An article having an aluminum oxide film, wherein the article is a composite in which an aluminum oxide film is attached to a substrate or a composite film having layers other than an aluminum oxide film and an aluminum oxide film is attached to a substrate. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete