JP3122082B2 - Manufacturing method of titanium oxide coated material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the removal of harmful substances,
A method for producing a coating material of titanium oxide, which is one of the photocatalysts used as an environmental purification material for deodorant decomposition, antifouling, sterilization, etc. of malodorous substances. When coated with, the photocatalytic function can be maintained for a long period of time, and the adhesion to the coated member can be maintained with high strength for a long period of time. The present invention relates to a method for producing a titanium oxide coated material capable of producing a binder which does not impair the adhesion strength.

[0002]

2. Description of the Related Art Photocatalysts are harmful substances (aldehydes, etc.) removed by radical substances (hydroxyl radicals, superoxide anions) generated when ultraviolet rays are irradiated on the surface, and malodorous substances (regulated by the Odor Control Law). Substances that have functions such as deodorization, decomposition, antifouling, and sterilization. In recent years, the use of the above functions has been attempted by coating this photocatalyst on the substrate surface, and many oxides can be used as photocatalysts, but titanium oxide is used as one of the photocatalysts. In particular, anatase-type titanium oxide is excellent in both functions and safety. That is, titanium oxide includes three types of crystals, anatase type, rutile type, and brookite type, and amorphous type (amorphous type). Titanium oxide having the largest photocatalytic activity is anatase type.

[0003] A conventional technique will be described for a method for producing a liquid containing titanium oxide and a slurry. JP-A-8-9904
As described in JP-A No. 1 (1999), polyethylene glycol or ethylene oxide is added to a titania sol prepared from an alkoxide of titanium and alcohol amines, and coated on a substrate.
By heating to a temperature of about 700 ° C., an anatase-type titanium oxide thin film is obtained. The above publication describes that the firing temperature is preferably from 600 ° C. to 700 ° C. JP-A-8-277147 also proposes a coating material prepared by a sol-gel method.
There is a firing step. JP-A-8-21557 also proposes that a coating material is prepared by diluting a titanium oxide sol obtained by hydrolyzing titanyl sulfate with water,
This also performs a baking treatment in the air at 300 ° C.

The present inventor has also proposed in Japanese Patent Application No. 10-142008 a method for producing anatase type titanium oxide. In the method described in the above-mentioned patent application, titanium isopropoxide is heated by heating a titania sol prepared by adding a small amount of water in isopropyl alcohol as an organic solvent in a closed container to evaporate isopropyl alcohol. The crystallization of anatase-type titanium oxide is promoted by utilizing the vapor pressure together with heat. In Japanese Patent Application Laid-Open No. H10-67516, a titanium hydroxide precipitate is first prepared from a titanium solution and a basic solution such as ammonia, and then hydrogen peroxide solution is added thereto. There is a proposal to crystallize type titanium oxide.

A technique for adding a third component other than titanium oxide and a technique for forming a precoat layer for the purpose of improving adhesion are described below. JP-A-8-131834 describes that a thermoplastic binder such as an acrylic resin or a thermosetting resin such as a fluororesin, an epoxy resin or a siloxane resin is formed on the surface of a base material. Further, a method of using PTFE, which is one of fluororesins, as a binder has been proposed ("The World of Photocatalyst", edited by the Industrial Technology Research Council, published in April 1998). In addition, there has been proposed a method for improving adhesion strength by precoating a base material with silica which is not decomposed by a photocatalyst, and thereafter coating a titanium oxide layer. As described above, as a binder for securing the adhesion strength to the member, silica (SiO
₂ ) and the like and polymers such as polymethyl methacrylate (PMMA) are added.

[0006]

When anatase-type titanium oxide is adhered to the surface of a member with high strength, as described in JP-A-8-99041 and JP-A-8-277147, a 300 It is necessary to treat at a high temperature of not less than ° C., and there is a problem that a titanium oxide coating cannot be applied to a member having low heat resistance. Further, the conventional binder used for improving the adhesion of titanium oxide has the following problems. JP-A-8-1318
As described in Japanese Patent Publication No. 34-34, when an organic substance is mixed, the decomposition of the organic substance by the photocatalyst occurs and the adhesion strength cannot be maintained, so that the long-term maintenance of the photocatalytic function is limited. Similarly, in polymers such as polymethyl methacrylate (PMMA), PMMA is decomposed by the photocatalytic function, and there is a limit in maintaining the adhesion strength. In the case of silica, the adhesion strength can be maintained, but a separate material is required, and the photocatalytic function is reduced. Further, the above-mentioned Japanese Patent Application Laid-Open No.
The technique described in Japanese Patent Application Publication No. H11-163, discloses a method for preparing a titanium hydroxide precipitate from a titanium solution and a basic solution, then adding a hydrogen peroxide solution, and further performing a heat treatment at 80 ° C. or higher.
In the present invention, the use of an organic solvent, the absence of a step of collecting a precipitate, and the ozone treatment performed at about 25 ° C. are completely different from the technology described in the above publication. . Further, in the conventional technique, as described in the above-mentioned publication, the coating step is two steps and is complicated.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to use a titania sol solution, a titania gel or a liquid obtained by treating a titania sol-gel mixture with ozone gas as a coating material for titanium oxide. Thereby, titanium oxide having an excellent photocatalytic function (particularly, anatase type titanium oxide) can be coated at a low temperature, and the adhesion to the coated member can be maintained with high strength for a long period of time. An object of the present invention is to provide a method for producing a titanium oxide coated material that does not impair the surface appearance of the member due to its excellent properties. The object of the present invention is
Titania sol solution, titania gel or titania sol
By mixing a liquid obtained by treating a gel mixture with ozone gas, a titania powder, and a titania slurry, a binder can be maintained over a long period of time for a material having high photocatalytic activity but low adhesion strength. It is an object of the present invention to provide a method for producing a titanium oxide coating material that can be used.

[0008]

Means for Solving the Problems To achieve the above object, a method for producing a titanium oxide coating material of the present invention comprises treating a titania sol solution, a titania gel or a titania sol-gel mixture with ozone gas at a low temperature. On the court
It is configured to obtain a titanium oxide coating material having excellent adhesion and transparency . Further, the method for producing a titanium oxide coating material of the present invention is a method of treating a titania sol solution, a titania gel or a titania sol-gel mixture with an ozone gas to obtain a titania powder, a titania slurry (a titanium oxide powder, a titanium oxide slurry and a mixture of these). At least one of them) to obtain a titanium oxide coating material.

In these cases, as a starting material for producing titania sol or titania gel, for example, titanium alkoxide, titanium oxalate, which is a metal organic compound,
Titanium nitrate and titanium tetrachloride can be used as the metal inorganic compound. Examples of the titanium alkoxide include titanium tetramethoxide, titanium tetraethoxide, titanium isopropoxide, titanium-n-propoxide, titanium tetra-n-butoxide, titanium tetraisobutoxide, titanium methoxypropoxide, and titanium dichloride die. And toxide. In these methods of the present invention, it is preferable that the titania sol solution, the titania gel or the titania sol-gel mixture contains water, an organic solvent or a mixture thereof, preferably an alcohol as a solvent.

As the solvent for dissolving the raw materials, any organic solvent and water may be used as long as they dissolve titania sol and titania gel. Organic solvents include alcohols, hydrocarbons, halogenated hydrocarbons, phenols,
There are ethers, esters and nitrogen compounds. As the organic solvent, specifically, hexane, toluene, benzene,
Xylene, cyclohexane, carbon tetrachloride, phenol,
Cresol, diethyl ether, dioxane, acetone, ethyl acetate, propyl acetate, acetonitrile, tetrahydrofuran, pyridine, etc.
It is desirable to use the _n H _{2n + 1} OH alcohol represented by the structural formula. For example, methanol, ethanol,
1-propanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, te
Examples thereof include r-butyl alcohol, 1-pentanol, 2-pentanol, and 3-pentanol. In the method of the present invention described above, the raw material of the titanium oxide coating material after the ozone treatment can be used after being diluted with an organic solvent, preferably an alcohol. As alcohols used for dilution, alcohols represented by the structural formula of C _n H _{2n + 1} OH, particularly isopropyl alcohol, are desirable. In addition, it is also possible to dilute using a mixed solution of an organic solvent other than alcohols and a plurality of organic solvents. The reason why the ozone-treated coating material is diluted with alcohol or the like is to improve the concentration of the coating material and to suppress gelation.

In the method of the present invention, at least one of an acidic substance, an alkaline substance, a surfactant and a metal alkoxide other than titanium is added to the titania sol solution, the titania gel or the titania sol-gel mixture. preferable. As described above, it is possible to add an acidic substance such as hydrochloric acid, nitric acid, and acetic acid, an alkaline substance such as ammonia and an amine compound, and a surfactant and a metal alkoxide other than titanium to a raw material such as titania sol, as necessary. it can. Other metal alkoxides include Al, Sb, Ba, Bi, B, Ca, Ce, Cs,
Cr, Cu, Ga, Hf, Fe, Li, Lu, Mg, M
o, Nb, Ni, Pd, Pt, Rh, Sm, Si, A
g, W, V, Y, Zn, Zr and the like. Further, a metal alkoxide containing a single metal or a plurality of metals may be contained.

[0012]

Next, an embodiment of the present invention will be described. In the present embodiment, as an example, a case is described in which titania sol is used as a raw material and alcohols represented by the structural formula of C _n H _{2n + 1} OH are used as a solvent for dissolving the titania sol. -It is of course possible to use the gel mixture as a raw material, and it is of course possible to use other organic solvents and water as long as the solvent dissolves titania sol or titania gel. As a starting material for producing a titania sol, for example, titanium alkoxide and titanium oxalate, which are metal organic compounds, and titanium nitrate and titanium tetrachloride as metal inorganic compounds can be used. Examples of the titanium alkoxide include titanium tetramethoxide, titanium tetraethoxide, titanium isopropoxide, titanium-n-
There are propoxide, titanium tetra-n-butoxide, titanium tetraisobutoxide, titanium methoxypropoxide, titanium dichloride diethoxide and the like. Examples of the solvent for dissolving the starting material or the titania sol include methanol, ethanol, 1-propanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutyl alcohol, ter-butyl alcohol, 1-pentanol, and 2-pentene. There are tanol and 3-pentanol.

[0013] Among the above-mentioned raw materials, for example, by using a liquid obtained by treating titanium hydroxide obtained by hydrolyzing a titanium alkoxide with ozone gas as a coating material of anatase type titanium oxide, it can be coated at a low temperature, In addition, a titanium oxide coating material having excellent transparency can be manufactured. As a method for producing ozone gas to be passed through the titania sol, a method of producing by silent discharge of oxygen gas or clean air, a method of electrolyzing dilute sulfuric acid at a low temperature with water, a method of heating liquid oxygen, and applying ultraviolet rays to air Although there are methods and the like, any method may be used. The temperature of the titania sol when flowing the ozone gas may be about 25 ° C., but heating and cooling may be performed. If necessary, an acidic substance such as hydrochloric acid, nitric acid, and acetic acid, an alkaline substance such as ammonia and an amine compound, a surfactant, and a metal alkoxide other than titanium can be added to the titania sol. For other metal alkoxides, it is also possible to hydrolyze the titanium alkoxide simultaneously or separately as if it had been hydrolyzed.

The solution subjected to the ozone treatment can be coated as it is and used as a photocatalyst, and can be mixed with an anatase-type titanium oxide powder or / and a slurry in which anatase-type titanium oxide is dispersed to increase the catalytic activity. It can also be done. As described above, the liquid subjected to the ozone treatment can be used as it is as a photocatalyst, and its activity can be increased by mixing with a powder or slurry of anatase-type titanium oxide prepared in advance. The anatase-type titanium oxide slurry added separately for increasing the activity is, for example, heating a titania sol solution, a titania gel or a titania sol-gel mixture in a closed vessel at a temperature in the range of 80 to 250 ° C. (preferably 240 ° C. or lower). Process and manufacture.
As a specific example, anatase-type oxidation produced by heating a titania sol prepared by adding a small amount of water to titanium isopropoxide in isopropyl alcohol at a temperature in the range of 80 to 250 ° C. in a closed container. Titanium slurry may be mentioned, but the titania powder and the method for producing the titania slurry are not limited at all, and the coating material produced by the method of the present invention may be any mixture of titania powder and slurry. Further, it can be used as a binder for increasing the fixing strength of a photocatalyst other than titanium oxide, for example, ZnO, CdS, or the like.

The titania sol solution, the titania gel or the titania sol-gel mixture is placed in a closed container at 80 to 2 times.
Ozone gas is passed through an anatase-type titanium oxide slurry produced by heat treatment at a temperature in the range of 50 ° C. (preferably 240 ° C. or less), and the anatase-type titanium oxide slurry is ozone-treated, thereby forming a binder in the slurry. It is also possible to manufacture. As a specific example, anatase-type oxidation produced by heating a titania sol prepared by adding a small amount of water to titanium isopropoxide in isopropyl alcohol at a temperature in the range of 80 to 250 ° C. in a closed container. There is a case where a binder for improving adhesion strength is produced by subjecting a titanium slurry to ozone treatment. Further, the liquid after the ozone treatment may be diluted with an organic solvent such as alcohol before use. For example, when diluting with isopropyl alcohol, a titanium oxide coating is possible at low temperatures of 110 ° C. or less. Further, the dilution ratio can control the thickness of the coating layer thereby, and can be adjusted depending on the member to be coated.

The member to be coated with the titanium oxide coating material of the present invention may be any member of an inorganic substance, an organic substance, a metal alone, or a composite of these. Coating is possible below 110 ° C. Examples of the inorganic substance include glass, pottery, cements, ceramics, sand, and the like, and inorganic substances processed into a fiber. Examples of the organic substance include thermoplastic resins such as polyethylene, ABS, polypropylene, polymethyl methacrylate, and fluororesin; thermosetting resins such as epoxy resin and polyurethane; FRP; and rubber. Examples of the metal material include aluminum, iron, copper, and the like, and a metal composite material of these materials without any limitation. The coating method of the coating material produced by the method of the present invention,
Any method such as brushing, spraying, spin coating, and dip coating can be used.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention and comparative examples will be described below. Example 1 Titanium isopropoxide (14.96 g) was dissolved in isopropanol (50 ml) to prepare a titanium isopropoxide solution, which was previously mixed with 2N hydrochloric acid (2.5 ml), water (3 ml), and isopropanol (94.5 ml) to give titanium isopropoxide. The solution was added dropwise at 10 ml per minute for 5 minutes, ie, 50 ml. The molar ratio of titanium isopropoxide, water, and hydrochloric acid in the obtained titania sol solution was 1: 3: 0.05. 250 ml of the obtained transparent titania sol 110 g
At a temperature of 25 ° C., and ozone (ozone generation amount 180 mg / Nl, oxygen flow rate 40 Nml / min) was passed for 60 minutes. 5 g of the liquid after ozone circulation is 35 g of isopropanol
(Weight ratio 1: 7). The solution coated on the surface of a glass substrate and dried at 110 ° C. for 30 minutes had a pencil hardness of 6H or more, and no peeling of the coating layer due to sticking and peeling of the adhesive tape was observed. The transparency of the glass was also very good.

The above-mentioned coating material is coated on the inner surface of a 1-liter separable flask made of glass with a brush.
Dry at 10 ° C. for 30 minutes. The amount of titanium oxide coated on the inner surface of the separable flask was 0.02 g. The separable flask after the titanium oxide coating was irradiated with a low-pressure mercury lamp (10 W) to evaluate the decomposition characteristics of 500 ppm of acetaldehyde. The result is shown in FIG. When the mercury lamp is not irradiated, the acetaldehyde concentration is
When injected into the flask, only about 10% of acetaldehyde was reduced by adsorption on the inner surface of titanium oxide.
Thereafter, the acetaldehyde concentration was maintained (corresponding to -30 minutes to 0 minutes in FIG. 1). By irradiation with a mercury lamp, the concentration of acetaldehyde in the gas atmosphere in the flask decreased, and the entire amount disappeared in about 50 minutes. Furthermore, when the carbon dioxide (decomposition product of acetaldehyde) in the flask was analyzed, the carbon dioxide concentration in the flask increased simultaneously with the irradiation of the mercury lamp. From these facts, it is understood that acetaldehyde was decomposed and removed by the photocatalyst.

Example 2 Transparent titania sol 110 prepared by the method described in Example 1
g in a 250 ml container and ozone at a temperature of 25 ° C. (ozone generation amount 180 mg / Nl, oxygen flow rate 40 Nml / min)
For 60 minutes. 5 g of the liquid after ozone circulation was diluted with 35 g of isopropanol (weight ratio 1: 7), and 0.5 g of anatase-type titanium oxide slurry produced by treating the transparent titania sol in a closed state at 240 ° C. for 3 hours was added. Thus, a titanium oxide coating material was obtained. When the coating material was coated on the surface of a glass substrate and dried at 110 ° C. for 30 minutes, the pencil hardness was 6H or more, and no peeling of the coating layer due to sticking and peeling of the adhesive tape was observed. The transparency of the glass was also very good.

The above-mentioned coating material is coated on the inner surface of a 1-liter separable flask made of glass with a brush.
Dry at 10 ° C. for 30 minutes. The amount of titanium oxide coated on the inner surface of the separable flask was 0.04 g. As in Example 1, the separable flask was irradiated with a low-pressure mercury lamp (10 W) to evaluate the decomposition characteristics of 500 ppm of acetaldehyde. The result is shown in FIG. When irradiation with a mercury lamp was not performed, the acetaldehyde concentration was reduced only by about 20% of acetaldehyde due to adsorption on the inner surface of titanium oxide when injected into the flask, and thereafter the acetaldehyde concentration was maintained (− in FIG. 2). 30 minutes to 0 minutes). The irradiation of the mercury lamp reduced the acetaldehyde concentration in the flask to about 4
At 0 minutes the whole amount was gone. Furthermore, when the carbon dioxide in the flask was analyzed, the carbon dioxide concentration in the flask increased simultaneously with the irradiation of the mercury lamp. From these facts, it can be seen that acetaldehyde was decomposed and removed by the photocatalyst with increased activity.

Example 3 Transparent titania sol 110 prepared by the method described in Example 1
g in a 250 ml container and ozone at a temperature of 25 ° C. (ozone generation amount 180 mg / Nl, oxygen flow rate 40 Nml / min)
For 60 minutes. 5 g of the liquid after ozone circulation was diluted with 35 g of isopropanol (weight ratio 1: 7), and anatase-type titanium oxide powder (P-25, manufactured by Nippon Aerosil Co., Ltd.)
Was added to obtain a titanium oxide coating material. When the coating material was coated on the surface of a glass substrate and dried at 110 ° C. for 30 minutes, the pencil hardness was 6H or more, and no peeling of the coating layer due to sticking and peeling of the adhesive tape was observed. The transparency of the glass was also very good.

The above coating material is coated on the inner surface of a 1-liter separable flask made of glass with a brush.
Dry at 10 ° C. for 30 minutes. The amount of titanium oxide coated on the inner surface of the separable flask was 0.04 g. In the same manner as in Example 1, the separable flask was irradiated with a low-pressure mercury lamp (10 W) and the decomposition characteristics of 500 ppm of acetaldehyde were evaluated.
All the acetaldehyde in the flask was decomposed into carbon dioxide. From these facts, it can be seen that acetaldehyde was decomposed and removed by the photocatalyst with increased activity.

Comparative Example 1 A low-pressure mercury lamp (10 W) was irradiated into a 1-liter glass separable flask to evaluate the decomposition characteristics of 500 ppm of acetaldehyde. The result is shown in FIG. Irradiation with a mercury lamp showed only a decrease in acetaldehyde due to adsorption on the inner surface of the flask, and no generation of carbon dioxide, which was a decomposition product of acetaldehyde.

[0024]

As described above, the present invention has the following effects. (1) Titanium oxide having an excellent photocatalytic function can be adhered to a member to be coated with high strength, and the adhesion strength can be maintained, and the photocatalytic function can be maintained for a long time. (2) The titanium oxide coating material produced by the method of the present invention can be coated at a low temperature, and can be coated on a material surface having low heat resistance. As an example,
When isopropyl alcohol is used as the diluent or the solvent, the titanium oxide coating can be performed at a low temperature of 110 ° C. or less. (3) The raw material after the ozone treatment can be used as it is as a photocatalyst, and when a photocatalyst prepared in advance, for example, an anatase-type titanium oxide powder or an anatase-type titanium oxide slurry is separately added, the catalytic activity is increased. be able to. (4) The titanium oxide coating material produced by the method of the present invention has excellent transparency and does not impair the appearance of the member to be coated. (5) In the step of manufacturing and coating the titanium oxide coating material, there is no step of collecting the precipitate of titanium hydroxide, and only the ozone treatment is performed, so that the step is simple.

[Brief description of the drawings]

FIG. 1 is a graph showing the results of testing the acetaldehyde decomposition characteristics of a coating material obtained in Example 1 of the present invention.

FIG. 2 is a graph showing the results of testing the acetaldehyde decomposition characteristics of a coating material obtained in Example 2 of the present invention.

FIG. 3 is a graph showing the test results of the decomposition characteristics of acetaldehyde in Comparative Example 1.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C09C 1/36 C09C 1/36 C09D 5/00 C09D 5/00 L // B05D 7/24 303 B05D 7/24 303C (58) Field surveyed (Int. Cl. ⁷ , DB name) C09D 1/00 C09D 5/00

Claims (5)

(57) [Claims] 1. A titanium oxide coating material obtained by treating a titania sol solution, a titania gel body or a titania sol-gel mixture with ozone gas to obtain a titanium oxide coating material which can be coated at a low temperature and has excellent adhesion and transparency. Manufacturing method. 2. The method for producing a titanium oxide coating material according to claim 1, wherein the titania sol solution, the titania gel body or the titania sol-gel mixture contains water, an organic solvent or a mixture thereof as a solvent. 3. The method for producing a titanium oxide coating material according to claim 1, wherein the titanium oxide coating material obtained by treating the titania sol solution, the titania gel body or the titania sol-gel mixture with ozone gas is diluted with an organic solvent. 4. Titania sol solution, titania gel or titania sol-gel mixture is treated with ozone gas,
4. The method for producing a titanium oxide coating material according to claim 1, wherein at least one of titanium oxide powder, titanium oxide slurry and a mixture thereof is mixed to obtain a titanium oxide coating material. 5. The titania sol solution, titania gel body or titania sol-gel mixture, wherein at least one of an acidic substance, an alkaline substance, a surfactant and a metal alkoxide other than titanium is added. The method for producing a titanium oxide coated material.