JP2018058914A - Composition for porous film formation, method for producing composition for porous film formation, method for producing porous film, laminate, and solar cell module - Google Patents

Abstract

[PROBLEMS] To provide a porous film-forming composition and a porous film-forming composition capable of forming a film excellent in antireflection, antifouling property against fingerprints, etc., and antifouling property against adhesive components and excellent removability. A method, a method for producing a porous film, a laminate, and a solar cell module are provided. SOLUTION: Polymer particles, a silica component derived from a silicate compound, metal oxide particles having a surface area average particle diameter of 1 nm to 30 nm, and a dispersion medium, and the content of the polymer particles in the composition It is 28 mass% to 37 mass% with respect to the total solid content, the content of the silica component derived from the silicate compound is 33 mass% to 67 mass% with respect to the total solid content in the composition, and metal oxidation Formation of porous film in which content of product particles is 5% by mass to 30% by mass with respect to the total solid content in the composition, and at least a part of the surface of the polymer particle is coated with a silica component made of a silicate compound Composition and its application. [Selection figure] None

Description

  The present disclosure relates to a composition for forming a porous film, a method for producing a composition for forming a porous film, a method for producing a porous film, a laminate, and a solar cell module.

  The aqueous coating solution containing silica fine particles uses a solvent containing water, and is used for various applications because the formed film has low surface energy and excellent transparency. Examples of the application include an antireflection film, an optical lens, an optical filter, a flattening film for a thin film transistor (TFT) of various displays, a dew condensation prevention film, an antifouling film, and a surface protective film. Among these, the antireflection film and the antifouling film are useful because they can be used for protective films for solar cell modules, surveillance cameras, lighting equipment, signs, and the like.

Various proposals have been made to improve light transmittance in optical films such as antireflection films.
For example, a coating composition suitable for optical film formability including core-shell type nanoparticles including a core material including a polymer and a shell material including a metal oxide has been proposed (see, for example, Patent Document 1). . It is described that the optical film obtained by baking this coating composition has voids inside and has good light transmittance.
Further, as a film having an excellent antifouling effect formed on a hard surface, a specific ratio of metal oxide particles having a particle diameter of 1 nm to 400 nm and a polymer emulsion containing a hydrolyzed silicon compound having a particle diameter of 10 nm to 800 nm. An organic-inorganic composite coating film having a low refractive index has been proposed (see, for example, Patent Document 2).
Furthermore, a water-dispersed composition for forming a porous film that includes synthetic resin particles, water, and colloidal silica and can form a porous film having excellent transparency by firing has been proposed (see, for example, Patent Document 3). .

Japanese Patent No. 2010-138358 Japanese Patent Laid-Open No. 2002-3820 Japanese Examined Patent Publication No. 7-110906

By the way, for the antireflection film used for the windshield of the solar cell module, in addition to the antireflection property and the antifouling property due to the hydrophilization of the surface, the adhesive component is difficult to adhere, and the adhesive component is Even when it adheres, good removability is required. This maintains the transparency of the antireflection film, the antifouling property of the surface, etc., when the adhesive component used when manufacturing the solar cell module adheres to the antireflection film. By being important for.
However, although the coating film formed using the coating composition described in Patent Document 1 has good light transmittance, the surface hydrophilicity is low, and oily dirt such as fingerprints easily adheres. Removability was not sufficient. In addition, the organic-inorganic composite coating described in Patent Document 2 has a high content ratio of metal oxide particles, good surface hydrophilicity, hardly adheres to fingerprints, etc., and has good antifouling properties, but antireflection It was inferior in removability when an adhesive component adhered due to unevenness on the surface.
The water-dispersed composition for forming a porous film described in Patent Document 3 is a composition for the purpose of forming a porous film having large voids and good antireflection properties but good moisture permeability and absorbability. In addition, since it has many communicating holes, it was inferior in removability when an adhesive component adhered.

An object of one embodiment of the present invention is to provide a composition for forming a porous film capable of forming a film excellent in antireflection, antifouling against fingerprints, etc., antifouling against adhesive components, and excellent removability. That is.
Another object of another embodiment of the present invention is to provide a composition for forming a porous film capable of forming a film excellent in antireflection, antifouling against fingerprints, antifouling against adhesive components, and removability. It is to provide a manufacturing method.
Another object of the present invention is to provide a method for producing a porous film excellent in antireflection, antifouling against fingerprints, antifouling against adhesive components, and excellent removability, a laminate, and a solar The object is to provide a battery module.

Means for solving the problems include the following embodiments.
[1] A polymer particle, a silica component derived from a silicate compound, a metal oxide particle having a surface area average particle diameter of 1 nm to 30 nm, and a dispersion medium, and the content of the polymer particle is all in the composition. It is 28 mass%-37 mass% with respect to solid content, Content of the silica component derived from a silicate compound is 33 mass%-67 mass% with respect to the total solid content in a composition, and is a metal oxide. The composition for forming a porous film, wherein the content of the particles is 5% by mass to 30% by mass with respect to the total solid content in the composition, and at least a part of the surface of the polymer particles is coated with a silica component derived from a silicate compound. object.

[2] The composition for forming a porous film as described in [1], wherein the surface area average particle diameter of the metal oxide particles is ½ or less of the particle diameter of the polymer particles.
[3] The composition for forming a porous film according to [1] or [2], wherein the metal oxide particles are silica particles.
[4] The composition for forming a porous film according to any one of [1] to [3], wherein the polymer particles are cationic particles.
[5] The composition for forming a porous film according to any one of [1] to [4], wherein the polymer particles are cationic (meth) acrylic particles.

[6] A step of preparing a mixture by mixing polymer particles and metal oxide particles having a surface area average particle diameter of 1 nm to 30 nm, and adding a silicate compound to the obtained mixture, The process for producing a porous film-forming composition according to any one of [1] to [5], comprising a step of obtaining polymer particles partially coated with silica.
[7] A step of forming a porous film-forming composition layer by applying the porous film-forming composition according to any one of [1] to [5] on a substrate; A step of firing the formed composition layer for forming a porous film.
[8] A laminate having a fired product of the composition for forming a porous film according to any one of [1] to [5] on a substrate.
[9] A solar cell module comprising the laminate according to [8].

According to one embodiment of the present invention, there is provided a composition for forming a porous film capable of forming a film excellent in antireflection, antifouling against fingerprints, etc., antifouling against adhesive components, and excellent removability. be able to.
According to another embodiment of the present invention, the production of a composition for forming a porous film capable of forming a film excellent in antireflection, antifouling against fingerprints, etc., antifouling against adhesive components and excellent removability A method can be provided.
According to another embodiment of the present invention, a method for producing a porous film excellent in antireflection, antifouling against fingerprints, etc., antifouling against adhesive components and removability, laminate, and solar A battery module can be provided.

  Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be appropriately modified within the scope of the object of the present invention. be able to.

In the present specification, a numerical range indicated using “to” means a range including the numerical values described before and after “to” as a minimum value and a maximum value, respectively.
In this specification, the amount of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific indication when there are a plurality of substances corresponding to each component in the composition. Means.
In this specification, one or both of acrylic and methacryl may be referred to as “(meth) acryl”, and one or both of acrylate and methacrylate may be referred to as “(meth) acrylate”, respectively.
In this specification, the term “process” is not limited to an independent process, and is included in this term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. It is.

[Porous film forming composition]
The composition for forming a porous film in the present disclosure (hereinafter sometimes simply referred to as “composition”) is a metal oxide having a polymer particle, a silica component derived from a silicate compound, and a surface area average particle diameter of 1 nm to 30 nm. Product particles and a dispersion medium, the content of the polymer particles is 28% to 37% by mass with respect to the total solid content in the composition, and the content of the silica component derived from the silicate compound is the composition The polymer particles are 33% by mass to 67% by mass with respect to the total solid content in the polymer, and the content of the metal oxide particles is 5% by mass to 30% by mass with respect to the total solid content in the composition. A composition for forming a porous film, wherein at least a part of the surface of the coating is coated with a silica component derived from a silicate compound.
Hereinafter, polymer particles in which at least a part of the surface of the polymer particles is coated with a silica component derived from a silicate compound may be referred to as “specific particles”.

The mechanism of action of the composition for forming a porous film in the present disclosure is not clear, but is estimated as follows.
In the composition for forming a porous film, the polymer particles are 28% by mass to 37% by mass relative to the total solid content in the composition, and the silica component derived from the silicate compound is based on the total solid content in the composition. Including 33% by mass to 67% by mass. Therefore, the film obtained by firing the composition becomes a porous film having a low refractive index due to the silica component matrix derived from the silicate compound and the pores formed by burning the polymer particles.
Furthermore, by forming specific particles in which at least a part of the surface of the polymer particles is coated with a silica component derived from a silicate compound, dense silica is formed on the outermost surface of the porous film obtained by firing the composition. A layer can be formed, and adhesion of an adhesive component can be suppressed.
Further, by containing 5% by mass or more of metal oxide particles having a surface area average particle diameter of 1 nm to 30 nm with respect to the total solid content of the composition, fine irregularities are formed on the surface of the film formed using the composition. Is formed, the water contact angle is lowered, and the antifouling property against fingerprints is improved.
On the other hand, when the content of the metal oxide particles with respect to the total solid content of the composition is 30% by mass or less, formation of aggregates of metal oxide particles to which adhesive components easily adhere can be suppressed.

Here, when the pores derived from the polymer particles are exposed on the surface of the porous membrane, the adhesive component attached to the membrane surface enters the pores and is difficult to remove, and is formed by the composition of the present disclosure. The porous membrane is excellent in removability even when an adhesive component adheres to the surface because the exposure of the pores to the surface is suppressed and the membrane has a good hydrophilicity and antifouling property. it is conceivable that.
According to a preferred embodiment of the present disclosure, in preparing the composition, a silicate compound that coats the polymer particles is added to the mixture of the polymer particles and the metal oxide particles, and the specific coating covered with the silica component is performed. Get particles. As a result, when specific particles formed by coating the polymer particles with the silica component are formed, a uniform coating layer that further contains the metal oxide particles in the silica component is easily formed, and the effects described above are more remarkable. It is estimated that
Note that the present disclosure is not limited to the estimation mechanism.

(Polymer particles whose surface is at least partially coated with a silica component: specific particles)
The composition in the present disclosure includes polymer particles, ie, specific particles, in which at least a part of the surface is coated with a silica component.
The specific particle is a core-shell type particle including a core portion including a polymer material and a shell portion including a silica component, and the shell portion is formed on at least a part of the surface of the polymer particle including the polymer material as the core portion. It only has to exist.

The polymer particles that are the core part preferably contain a polymer that can be removed when forming a porous film using the composition to form pores. As an aspect removed at the time of film formation, thermal decomposition, photodecomposition, solvent washing, decomposition by irradiation with active radiation such as an electron beam, and the like are mentioned, and thermal decomposition is preferable from the viewpoint that the process is simple.
In a preferred embodiment, the polymer particles contained in the core portion comprise a thermally decomposable polymer or a thermally labile polymer. Hereinafter, “thermal decomposition or thermal destabilization” may be collectively referred to as “thermal decomposition”.
As the thermally decomposable polymer, a polymer that thermally decomposes at 600 ° C. or lower is preferable, a polymer that thermally decomposes at 450 ° C. or lower is more preferable, and a polymer that thermally decomposes at 350 ° C. or lower is more preferable. A polymer that thermally decomposes at room temperature or higher is preferable, a polymer that thermally decomposes at 150 ° C. or higher is more preferable, and a polymer that thermally decomposes at 250 ° C. or higher is more preferable.
The thermally decomposable polymer may be, for example, a homopolymer, a copolymer containing a thermally decomposable monomer, or a mixture thereof.

  Thermally decomposable polymers include polymers selected from polyesters, polyamides, polycarbonates, polyurethanes, polystyrenes, poly (meth) acrylates, and combinations thereof.

Especially, it is preferable that poly (meth) acrylate is included as a thermally decomposable polymer. As used herein, poly (meth) acrylate refers to a homopolymer or copolymer comprising one or more vinyl monomers.
Examples of suitable monomers included in the thermally decomposable polymer include styrene, alpha-methylstyrene, o-, m-, and p-methylstyrene, o-, m-, and p-ethylstyrene, p-chlorostyrene. , Styrene monomers such as p-bromostyrene, C1-C12 alkanols, C5-C12 cycloalkanol linear and branched acrylic and methacrylic esters, vinyl esters, vinyl halides, vinylidene halides, dienes Etc.

The monomer contained in the thermally decomposable polymer may include a monomer having a functional group such as a crosslinkable group. Examples of the crosslinkable group include a hydroxy group and an epoxy group.
Specific examples of the monomer having a functional group include, for example, a (meth) acrylic acid hydroxyalkyl ester containing an alkyl group having 1 to 12 carbon atoms, a monomer having a keto and aldehyde group, and a (meth) acrylic acid hydroxyalkyl ester. Acetoacetoxy ester, keto or aldehyde-containing amide. Examples of the monomer having a tertiary amino group include vinyl monomers having a nonionic amino group. Cyclic ureido or thiourea-containing unsaturated monomers, mixtures of vinyl monomers having amino groups, and the like can also be used.

These monomers having amino groups may be converted into cationic monomers by neutralization, if desired.
As the cationic monomer, a vinyl monomer having a quaternary ammonium group, specifically, for example, methacrylamidopropyltrimethylammonium chloride (MAPTAC), diallyldimethylammonium chloride (DADMAC), 2-trimethylammonium ethyl methacrylate (TMAEMC) is used. ), (Meth) acrylic acid and quaternary ammonium salts of (meth) acrylamide monomers. In the case of a vinyl monomer having an amino group that is already cationic, such as the vinyl monomer having a quaternary ammonium group described above, cationization by neutralization is not necessary.

The polymer material contained in the polymer particles is preferably cationic. That is, it is preferable that the polymer particles are cationic particles.
When the polymer particles are cationic, the affinity with the shell portion containing the silica component is further improved, and the adhesion of the metal oxide particles described later is further improved.
As described above, the polymer material is preferably an acrylic material, and the polymer particles are more preferably cationic (meth) acrylic particles.
More specifically, for example, polymer particles containing (meth) acrylate containing a tertiary aminoalkyl group and the like can be mentioned.

As the polymer particles constituting the core portion, it is preferable to use polymer particles in a latex state, more preferably an ionically stabilized polymer latex. As used herein, “latex” refers to a stabilized suspension or dispersion of polymer particles. The suspension or dispersion is preferably cationic.
1-9 are preferable and, as for pH of latex, 3-7 are more preferable.
In addition to containing cationic polymer particles, the latex can also be made cationic by containing a cationic surfactant, such as a quaternary ammonium salt surfactant.
The shape of the polymer particles is not particularly limited, and may be any shape such as a spherical shape or an elliptical shape, but is preferably a spherical shape.

  The pH of the composition in this specification is a value measured at 25 ° C. using a pH meter (model number: HM-31, manufactured by Toa DKK Co., Ltd.).

The number average particle diameter of the polymer particles is preferably in the range of 10 nm to 80 nm, more preferably 20 nm to 70 nm, and further preferably in the range of 30 nm to 60 nm.
In addition, the value measured by the dynamic light scattering method is employ | adopted for the number average particle diameter of the polymer particle in this specification.
The number average particle diameter of the polymer particles can be measured using a nanotrack particle size distribution analyzer UPA-EX150 (manufactured by Nikkiso Co., Ltd.).

As the polymer particles that are the core portion of the specific particles, a synthetic product obtained by suspension polymerization or the like may be used, or a commercially available product may be used. Examples of commercially available polymer particles that can be used in the composition include Neokrill (registered trademark) XK-30 (number average particle size (Mn) 49 nm) manufactured by DMS Neoresins Co., Ltd. Neocryl® XK-30 is an acrylic copolymer latex particle that is stabilized with a cationic surfactant. For example, use this particle. By using tetramethoxysilane (TMOS) as a silicate compound, specific particles can be easily obtained in a neutral aqueous environment at room temperature.
Examples of other commercially available cationic polymer particles include Nippon Synthetic Chemical Industry Co., Ltd., Acrylic Polymer Cationic Movinyl (registered trademark) 7800, Movinyl 7810, Movinyl 7820, Nippon Shokubai Co., Ltd., Eposter (registered trademark) SS, Eposter S Melamine / formaldehyde condensate, manufactured by Nissin Chemical Industry Co., Ltd., Viniblanc (registered trademark) 2678, manufactured by Unitika, Arrow Base (registered trademark) CB-1200, Arrow Base CD-1200, modified polyolefin resin aqueous dispersion Arrow Base, etc. Can be mentioned.

The specific particles described above include a silica component as a shell portion on at least a part of the surface.
As a material for the shell portion, it is preferable to include at least one silica component derived from a silicate compound attached on the surface of the polymer particle which is the material for the core portion described above.
The silicate compound may include an inorganic silicate, for example, an alkali metal silicate such as sodium silicate.
Moreover, an organic silicate compound is mentioned as a preferable silicate compound. Examples of organosilicate compounds include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetramethoxysilane partial hydrolysis condensate (methyl silicate oligomer), and tetraethoxysilane partial hydrolysis condensate (ethyl silicate). Oligomers), methyltrimethoxysilane, methyltriethoxysilane, glycidoxypropyltrimethoxysilane, glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and the like.
Commercially available products may be used as the silicate compound. Examples of commercially available products include methyl silicate oligomer, MKC silicate MS51 (SiO ₂ min 52 mass%, manufactured by Mitsubishi Chemical Corporation), MKC silicate MS56 (SiO ₂ min 56 mass). %, Manufactured by Mitsubishi Chemical Corporation), MKC silicate MS57 (SiO ₂ min 58 mass%, manufactured by Mitsubishi Chemical Corporation), ethyl silicate 28 (SiO ₂ min 28 mass%, manufactured by Colcoat Co., Ltd.), ethyl silicate 40 (SiO ₂ min. 40 mass%, manufactured by Colcoat Co., Ltd.), ethyl silicate 48 (SiO ₂ min. 48 mass%, manufactured by Colcoat Corp.), KBE-13 (manufactured by Shin-Etsu Chemical Co., Ltd.), KBE-403 ( Shin-Etsu Chemical Co., Ltd.), KBE-903 (Shin-Etsu Chemical Co., Ltd.) and the like.

  By treating the polymer particles with the silicate compound described above, the uncrosslinked copolymer chains contained in the polymer particles can be effectively crosslinked. For this reason, dissociation of the copolymer chain from the polymer particles is suppressed, the adsorptivity of the silica component on the surface of the polymer particles becomes better, and specific particles having better stability can be obtained.

The coating of the polymer particles with the silica component can be performed by treating the polymer particles with a suitable silicate compound under mild conditions. For example, specific particles can be obtained by bringing polymer particles into contact with the silicate compound described above in a latex state and stirring for 10 minutes to 300 minutes under conditions of a temperature of 5 ° C. to 60 ° C. and a pH of 2 to 9. .
Taking PDPA-PDMA copolymer as an example, specific particles can be obtained by contacting a dispersion of PDPA-PDMA copolymer with tetramethoxysilane and treating at 20 ° C. and pH 7.2 for 20 minutes.
Thus, it is one of the advantages in the present disclosure that specific particles in which at least a part of the surface is coated with a silica component can be obtained under mild conditions.
Details of the method for producing the specific particles will be described later.
The presence of the silica component on at least a part of the polymer particle surface can be confirmed by observing the particle with a transmission electron microscope.

  The content of the silica component derived from the silicate compound is preferably 33% by mass to 67% by mass, more preferably 40% by mass to 65% by mass, and 45% by mass with respect to the total solid content in the composition. It is more preferable that it is% -60 mass%.

The composition for forming a porous film may contain only one type of polymer particle or two or more types of polymer particles.
The content of the polymer particles in the composition for forming a porous film is 28% to 37% by mass, preferably 30% to 36% by mass, and preferably 32% to 35% with respect to the total solid content in the composition. The mass% is more preferable.
When the content of the polymer particles is within the above range, the content ratio between the polymer particles and the silica component derived from the silicate compound is in a suitable range, and the film formed of the composition becomes a porous film having a low refractive index.

(Metal oxide particles having a surface area average particle diameter of 1 nm to 30 nm)
The composition for forming a porous film in the present disclosure contains 5% by mass to 30% by mass of metal oxide particles having a surface area average particle diameter of 1 nm to 30 nm with respect to the total solid content in the composition.

The value measured by the BET method or the Sears method is used for the surface area average particle diameter of the metal oxide particles in this specification. When measuring the particle size of small metal oxide particles having an average particle size of 10 nm or less, the Sears method is preferred.
For example, according to the BET method which is an example of the surface area average particle diameter, the surface area average particle diameter of the metal oxide particles can be obtained by a nitrogen adsorption method using the BET equation (Brunauer, Emmett, Teller's equation). . The Sears method, which is an example of the surface area average particle diameter, W. Sears, Jr. "Analytical Chemistry" Vol. 28, p1981 to 1983 (1956), which is a method for determining the equivalent diameter of irregularly shaped particles, which is required for titrating colloidal silica corresponding to 1.5 g of SiO ₂ from pH 4 to pH 9. The specific surface area of colloidal silica obtained from the amount of .1N-NaOH and the equivalent diameter calculated therefrom.
The surface area average particle diameter of the metal oxide particles may be measured by a known method, or the catalog value of the metal oxide particle manufacturer can be referred to.
From the viewpoint of the effect, the particle size of the metal oxide particles contained in the composition is preferably smaller than the particle size of the specific particles described above. More preferably, it is 1/2 or less.
Specifically, the surface area average particle diameter of the metal oxide particles is 1 nm to 30 nm, preferably 1 nm to 20 nm, and more preferably 1 nm to 15 nm.

The metal oxide particles are preferably highly transparent and light transmissive particles.
Note that the metal of the metal oxide particles in this specification includes semimetals such as B, Si, Ge, As, Sb, and Te.
Examples of the metal oxide particles having good light transmittance include Be, Mg, Ca, Sr, Ba, Sc, Y, La, Ce, Gd, Tb, Dy, Yb, Lu, Ti, Zr, Hf, Nb, and Mo. , Oxide particles containing atoms such as W, Zn, B, Al, Si, Ge, Sn, Pb, Sb, Bi, and Te.

  As metal oxide particles, silicon oxide (silica) particles, aluminum oxide (alumina) particles, titanium oxide particles, titanium composite oxide particles, zinc oxide particles, zirconium oxide particles, indium / tin oxide particles, antimony / tin oxide Product particles are preferred, silica particles and alumina particles are more preferred, and silica particles are more preferred.

The kind of silica particle which is a preferable metal oxide particle is not particularly limited. Examples of the silica particles include hollow silica particles, porous silica particles, and nonporous silica particles.
The shape of the silica particles is not particularly limited, and may be any shape such as a spherical shape, an elliptical shape, or a chain shape.
The silica particles may be silica particles whose surfaces are treated with an aluminum compound or the like.

The silica particles contained in the composition for forming a porous film are preferably nonporous silica particles among the silica particles described above.
“Nonporous silica particles” mean silica particles having no voids inside the particles, and are distinguished from silica particles having voids inside the particles such as hollow silica particles and porous silica particles. The “non-porous silica particles” have a core such as a polymer inside the particles, and the outer shell (shell) of the core is silica or a precursor of silica (for example, a material that changes to silica by firing). The core-shell structured silica particles are not included.

In the production of a porous membrane, the state of particles present in the membrane may change before and after firing in the production of the porous membrane. Specifically, each nonporous silica particle is present as a single particle in the film before firing, that is, in the composition film for forming a porous film. The nonporous silica particles may take a state of being aggregated by van der Waals force or the like in the composition. Even if the aggregate is formed in this way, each particle exists independently of each other, and therefore, the particles in the aggregate state are also included in the single particle.
After firing the composition layer prepared by applying the aforementioned porous film-forming composition, at least some of the plurality of nonporous silica particles are connected to each other in the formed porous film. May form an aggregate of particles. When the silica particles contained in the composition for forming a porous film are non-porous silica particles, a plurality of non-porous silica particles are connected by firing to form a particle-linked body. This has the advantage that the hardness of the porous film is increased and the scratch resistance is further improved.

  The average primary particle size of the particles, which are particles connected by firing, is the arithmetic average of the diameters when only one of the connected particles is assumed to be a sphere without considering the connecting portion (for example, the neck portion). The value obtained by doing is adopted.

  Commercially available products may be used as the metal oxide particles. Commercial products may take the form of dispersions. Examples of commercially available products that can be used in the composition include SNOWTEX (registered trademark) OXS (pH 2.0 to 4.0, spherical, particle size 4 nm to 6 nm, solid content 10% by mass), SNOWTEX as silica particles. OS (pH 2.0 to 4.0, spherical, particle size 8 nm to 11 nm, solid content 20% by mass), Snowtex O-40 (pH 2.0 to 4.0, spherical, particle size 20 nm to 25 nm, solid content 40) Mass%), Snowtex OL (pH 2.0 to 4.0, spherical, particle size 40 nm to 50 nm, solid content 20 mass%), Snowtex OYL (pH 2.0 to 4.0, spherical, particle size 50 nm to 80 nm) , Solid content 20% by mass), Snowtex OUP (pH 2.0 to 4.0, chain, primary particle size 10 nm to 20 nm, secondary particle size 40 nm to 100 nm, solid content 15% by mass), Snowtex C pH 8.5 to 9.0, spherical, particle size 10 nm to 15 nm, solid content 20% by mass), Snowtex AK (pH 4.0 to 6.0, spherical, particle size 10 nm to 15 nm, solid content 18% by mass), Organosilica sol IPA-ST (isopropanol dispersion, particle size 10 nm to 15 nm, solid content 30% by mass, above, manufactured by Nissan Chemical Industries, Ltd.), NALCO (registered trademark) 8699 (aqueous dispersion of nonporous silica particles, Average primary particle size: 3 nm, solid content: 15% by mass, manufactured by NALCO, NALCO (registered trademark) 1130 (aqueous dispersion of nonporous silica particles, average primary particle size: 8 nm, solid content: 30% by mass, NALCO). Examples of the alumina particles include alumina sol AS-520 (pH 3 to 5, particle size 15 nm to 30 nm, solid content 20% by mass, manufactured by Nissan Chemical Industries, Ltd.).

The composition may contain only one kind of metal oxide particles or two or more kinds. When two or more types are included, particles having different compositions may be used, or particles having different particle sizes may be used.
The content of the metal oxide particles in the composition is 5% by mass to 30% by mass with respect to the total solid content of the composition, preferably 5% by mass to 20% by mass, and more preferably 5% by mass to 15% by mass. preferable. When the content of the metal oxide particles is in the above range, in the relation with the specific particles, the exposure of the pores in the porous film formed after firing to the film surface is suppressed, and the formed film Good hydrophilicity and antifouling properties.

(Dispersion medium)
The composition for forming a porous film includes a dispersion medium.
Examples of the dispersion medium include water and hydrophilic organic solvents.
The composition may include water as a dispersion medium. It is preferable to include water as the dispersion medium because the burden on the environment is reduced as compared with the case where a large amount of a volatile organic solvent is used.
The water is preferably ion-exchanged water, pure water or the like that does not contain impurities or has its content reduced as much as possible.

As the dispersion medium, a hydrophilic organic solvent may be included.
By including a hydrophilic organic solvent as a dispersion medium, the surface tension of the composition becomes lower and a more uniform coating film can be formed. In addition, for example, by including a low-boiling organic solvent having a boiling point of 120 ° C. or less as the hydrophilic organic solvent, there are advantages such as easy drying of the coating film of the formed composition.

  The hydrophilic organic solvent is not particularly limited. Examples of the hydrophilic organic solvent that can be contained in the composition include methanol, ethanol, isopropanol, butanol, acetone, ethylene glycol, and ethyl cellosolve. From the viewpoint of easy availability and reduction of environmental burden, the hydrophilic organic solvent is preferably alcohol, and more preferably ethanol, isopropanol, or the like.

  When the composition contains a hydrophilic organic solvent in addition to water as a dispersion medium, the content of water as the dispersion medium is preferably 30% by mass or more, and 40% by mass with respect to the total mass of the composition. More preferably.

  The solid content in the composition is preferably 0.1% by mass to 30% by mass, more preferably 0.2% by mass to 20% by mass with respect to the total mass of the composition. More preferably, it is 5 mass%-10 mass%. The amount of solid content contained in the composition can be adjusted by the content of the dispersion medium, particularly water.

The composition for forming a porous film may contain other components in addition to the above-described polymer particles, silica components, metal oxide particles, and dispersion medium as necessary, as long as the effects of the present disclosure are not impaired. Good.
Examples of other components include surfactants, water-soluble polymers, preservatives, chelating agents, and pH adjusters.

(Method for producing composition for forming porous film)
The composition for forming a porous film in the present disclosure can be adjusted by mixing the components described above.
The specific particles can be formed in the composition by dispersing polymer particles as a raw material in a dispersion medium and then adding a silicate compound which is a silica precursor.
In the preparation of the composition, the metal oxide particles may be added after the silicate compound is added to the polymer particles and the specific particles are prepared, or the metal oxide particles are added before the silicate compound is added. The silicate compound may be added after thoroughly mixing.

Among them, the method for producing a composition for forming a porous film includes a step of preparing a mixture by mixing polymer particles and metal oxide particles, and adding a silicate compound to the resulting mixture to form a surface. It is preferable to include a step of obtaining polymer particles in which at least a part of is coated with a silica component. The dispersion medium may be added at any step.
The polymer particles and the metal oxide particles before being coated with the silica component are mixed to prepare a mixture, whereby the polymer particles and the metal oxide particles are uniformly mixed. Thereafter, when a silica component coating layer is formed on the surface of the polymer particles by adding a silicate compound as a silica precursor, a part of the fine metal oxide particles is taken into the coating layer, or the coating layer Metal oxide particles may adhere to the surface of the surface. Therefore, the region covered with the silica component formed on at least a part of the polymer particle surface contains the metal oxide particles, and the silica component coating layer is formed on the periphery of the pores formed during firing at the time of film formation. In addition, the metal oxide particles are present alone or in a state of being bonded to each other, and a dense coating layer is formed on the peripheral edge of the pore, so that the exposure of the pore to the film surface is more effective. Since the metal oxide particles are more uniformly present on the film surface, the hydrophilicity, antifouling property and the like are improved.

[Method for producing porous membrane]
A manufacturing method for forming a porous film using the above-described composition for forming a porous film will be described.
A method for producing a porous film in the present disclosure includes a step of forming a porous film-forming composition layer by applying the porous film-forming composition in the present disclosure described above on a substrate. And baking the composition layer for forming a porous film.

[Step of forming a composition layer for forming a porous film]
In this step, on the substrate, the aforementioned porous film-forming composition is applied to form a porous film-forming composition layer.
There is no restriction | limiting in particular in the provision method of the composition on a base material, You may take any methods, such as a coating method and an immersion method. From the viewpoint that a composition layer having a uniform thickness can be easily formed, a coating method is preferable.
As the coating method, any known coating method such as spray coating, brush coating, roller coating, bar coating, dip coating, etc. can be applied.

The application amount of the composition is not particularly limited, and can be appropriately set according to the solid content concentration, desired film thickness, and the like in the composition.
As a measure of the film thickness of the composition layer, from the viewpoint of transparency, antifouling properties and film strength, the film thickness after drying of the composition ability is the number average particle diameter of the polymer particles contained in the composition. It is mentioned that it is 2 times or more.
In general, the thickness of the composition layer after drying is preferably 50 nm to 350 nm, more preferably 100 nm to 250 nm, and even more preferably 100 nm to 200 nm.
When the film thickness of the composition layer after drying is within the above-described range, a porous film having better antireflection properties can be formed.

  In addition, you may implement the process of drying the formed composition layer prior to the process of baking the composition layer mentioned later.

The composition layer may be dried at room temperature (25 ° C.) or using a heating device. The heating device is not particularly limited as long as it can be heated to a target temperature, and any known heating device can be used.
As the heating device, an oven, an electric furnace, or the like, or a heating device uniquely manufactured according to the production line can be used.
In the case of drying the composition layer, for example, the composition layer may be heated at an atmospheric temperature of 40 ° C. to 400 ° C. using the above heating device. In the case of performing heat drying, for example, the heating time can be about 1 minute to 30 minutes.
As a condition for drying the composition layer, a drying condition of heating at an atmospheric temperature of 40 ° C. to 200 ° C. for 1 minute to 10 minutes is preferable, and heating is performed at an atmospheric temperature of 100 ° C. to 180 ° C. for 1 minute to 5 minutes. Drying conditions are more preferred.
The thickness of the composition layer after drying is preferably 50 nm to 350 nm as described above.

[Step of firing the formed porous membrane-forming composition layer]
In this step, the formed composition layer is fired. By firing, pores are formed by the disappearance of the polymer particle portion in the specific particles contained in the composition layer, and the antireflection property is remarkably improved.
In addition, since the pores are covered with a silica coating layer, which is an inorganic component, and a combination of metal oxide particles, the periphery of the pores is effective to expose the surface of the porous film formed after firing. Is suppressed.
Moreover, by baking the composition layer, the hardness of the film of the composition layer is further increased, and the scratch resistance is further improved.

Firing of the composition layer can be performed using a heating device. The heating device is not particularly limited as long as it can be heated to a target temperature, and any known heating device can be used. As the heating device, in addition to an electric furnace or the like, it is possible to use a firing device uniquely produced in accordance with a production line.
The firing temperature of the composition layer can be appropriately determined according to the type and size of the polymer particles.
For example, the firing temperature (atmosphere temperature) can be 450 ° C. or higher and 800 ° C. or lower, preferably 500 ° C. or higher and 800 ° C. or lower, and more preferably 600 ° C. or higher and 800 ° C. or lower. The firing time is preferably 1 minute to 10 minutes, and more preferably 1 minute to 5 minutes.

The porous film formed after firing preferably has a film thickness of 50 nm or more. When the film thickness is 50 nm or more, the fired porous film is more excellent in antireflection properties.
The porous film after firing preferably has a thickness of 50 nm to 350 nm, more preferably 100 nm to 250 nm, and particularly preferably 100 nm to 200 nm.

[Other processes]
In the production method of the porous membrane, as long as the effect is not impaired, the step of applying the above-described composition, the step of firing the composition layer, the step of drying the composition layer that is preferably performed, as necessary In addition, other steps may be included.
Examples of other processes include a cleaning process, a surface treatment process, and a cooling process.

<Base material>
In the method for producing a porous membrane, the base material to which the composition layer is applied is not particularly limited, and is appropriately selected according to the use of the porous membrane.
Examples of the substrate include substrates such as glass, resin, metal, ceramic, and composite materials thereof, and any of these substrates can be suitably used. Among these, a glass substrate is preferable as the substrate. When a glass substrate is used as the substrate, the condensation of hydroxyl groups is not limited to the hydroxyl groups of the silica contained in the composition layer or the silica particles preferably contained, but also the hydroxyl groups of the silica and the glass surface hydroxyl groups. Since it also occurs between the base and the base, it is possible to form a porous film that is more excellent in adhesion to the substrate.

(Preferable physical properties of porous membrane)
The porous film in the present disclosure is preferably obtained by the method for producing a porous film described above using the composition produced by the method for producing a composition described above. The porous film manufactured by the above-described manufacturing method is excellent in antireflection, scratch resistance, and antifouling properties, and further, since the exposure of pores to the film surface is suppressed, the adhesive component is Excellent removability when attached.
Below, the preferable physical property of the porous membrane manufactured by the manufacturing method as stated above is shown.

<Antireflection>
The antireflection property of the porous film is evaluated by the following method.
Using a UV-visible-infrared spectrophotometer (model number: UV3100PC, manufactured by Shimadzu Corporation), the transmission spectrum at a wavelength of 400 nm to 1100 nm of the glass on which the porous film is formed is measured.
The difference (ΔT) between the average transmittance (Tav) at a wavelength of 400 nm to 1100 nm of the obtained transmission spectrum and the average transmittance (T ₀ av) of the glass substrate not forming the porous film is expressed by the following formula (1 ).
In the formula (1), ΔT indicates that the higher the numerical value, the better the antireflection property.

ΔT = Tav−T ₀ av equation (1)

  The absolute value of the average reflectance change ΔT in the porous film obtained at least after drying and baking is required to be 2.0% or more and 2.5% or more from the viewpoint of antireflection properties. More preferred.

<Film thickness>
The porous film preferably has a film thickness of 50 nm to 350 nm, more preferably 100 nm to 250 nm, and still more preferably 100 nm to 200 nm, from the viewpoint of antireflection properties.

<Water contact angle>
Using a contact angle meter (Dropmaster 500, manufactured by Kyowa Interface Science Co., Ltd.), 1 μL of water droplet is dropped on the surface of the porous membrane, and the static contact angle of the water droplet is measured.
Since the antifouling property becomes better due to the hydrophilic property, the water contact angle needs to be 20 ° or less, preferably 15 ° or less, and more preferably 10 ° or less.

<Fingerprint wiping>
After the fingerprint is attached to the porous film, it can be evaluated by observing the remaining fingerprint visually after wiping it with Bencot (registered trademark: non-woven wiper manufactured by Asahi Kasei Co., Ltd.) moistened with water. Fingerprint wiping is an indicator of how hard oily dirt adheres.

<Tape peelability>
In the present specification, tape peelability is used as an index of removability when an adhesive component adheres to the porous membrane. When a tape having an adhesive layer on a substrate is affixed to a porous membrane, it is a good indication that the tape has good removability, so that the adhesive component attached to the porous membrane is easily removed. It becomes.
Nichiban cello tape (registered trademark) CT-24 (width 25 mm) is attached to the porous membrane, and a 180 ° peel test is performed using a tensile tester (Tensilon RTF-1310, product name: A & D Co., Ltd.). The peel force (N) when measured is measured. It shows that tape peelability is so favorable that peeling force is small. The tape peelability is required to be 7 N / 25 mm or less, and preferably 5 N / 25 mm or less.

[Laminate]
The laminate in the present disclosure is a laminate having a fired product of the porous film forming composition in the present disclosure described above on a base material.
The laminate having a porous film that is a fired product of the composition on a substrate is preferably obtained by the method for producing a porous film described above.
Since the laminate has the porous film described above, it has excellent anti-reflection properties, scratch resistance, anti-stain properties, and removability when adhesive components are attached.
The base material in a laminated body is not specifically limited. Examples of the substrate include substrates such as glass, resin, metal, ceramic, and composite materials thereof, and any of these substrates can be suitably used.
As described above, a glass substrate is preferable as the substrate from the viewpoint of better adhesion between the porous membrane and the substrate.

<Refractive index>
The refractive index of the laminate when the porous film is provided on the glass substrate is preferably 1.3 or less.
The refractive index can be obtained by measuring the glass substrate on which the porous film is formed with an ellipsometer, and obtaining the refractive index at a wavelength of 633 nm.

  A laminate having a porous film manufactured by the above-described manufacturing method on a glass substrate is excellent in antireflection, scratch resistance, and antifouling properties. For example, a solar cell module, a monitoring camera, and a lighting device And can be suitably used for applications such as a protective film for a label.

[Solar cell module]
The solar cell module in this indication is provided with the above-mentioned layered product.
When a solar cell module is attached to a solar cell element that converts light energy of sunlight into electrical energy, antireflection, scratch resistance, antifouling, and adhesive components provided on the side where sunlight enters It can be configured by being disposed between a laminate having a porous film having excellent removability and a solar cell backsheet represented by a polyester film. Between the laminated body in this indication, and back sheets for solar cells, such as a polyester film, it seals with sealing materials represented by resin, such as ethylene-vinyl acetate copolymer, for example.
Even when the sealing material used when incorporating the laminated body into the solar cell module adheres to the porous film in the laminated body, for example, the surface is smooth and the exposure of the opening due to the pores is suppressed. Therefore, the sealing material does not adhere firmly to the surface, and the attached sealing material can be easily removed. For this reason, the yield in the assembly of the solar cell module is significantly improved by using the laminate in the present disclosure.

  Regarding members other than the laminate and the back sheet, such as a solar battery module and a solar battery cell, for example, see “Solar power generation system constituent materials” (supervised by Eiichi Sugimoto, Industrial Research Co., Ltd., issued in 2008). Have been described. The solar cell module preferably includes the above-described laminated body in the present disclosure on the side on which sunlight enters, and other configurations other than having the laminated body are not limited.

  As a base material provided in the side which sunlight injects, transparent resins, such as a glass base material and an acrylic resin, etc. can be mentioned, for example, Preferably it is a glass base material.

There is no restriction | limiting in particular as a solar cell element used for a solar cell module. The solar cell module in the present disclosure includes silicon-based solar cell elements such as single crystal silicon, polycrystalline silicon, and amorphous silicon, copper-indium-gallium-selenium, copper-indium-selenium, cadmium-tellurium, gallium-arsenide, etc. Any of various known solar cell elements such as III-V or II-VI compound semiconductor solar cell elements can be applied.
The solar cell module has a porous film on a base material (preferably a glass base material) having a good antireflection property, scratch resistance, antifouling property, and good removability when an adhesive component is attached. Therefore, even if it is used for a long period of time, the porous film on the surface is prevented from being damaged or the light transmittance due to the adhering contaminants is prevented from being reduced. In addition, since the adhesive component is difficult to adhere and can be easily removed even if it adheres, good power generation efficiency is maintained over a long period of time.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to the following examples as long as the gist thereof is not exceeded. In Examples, “%” represents “mass%” unless otherwise specified.

[Example 1]
[Preparation of Composition 1 for Forming Porous Film]
After mixing 9.7 g of water and 0.8 g of 10% aqueous acetic acid, polymer particles Neoacryl (registered trademark) XK-30 (cationic acrylic particles, particle size 63 nm, solid content 45.5%, DSM Neo Resins Co., Ltd.) 2.35 g)) was added and stirred at room temperature, and 3.15 g of MKC silicate MS51 (SiO ₂ min 52%, Mitsubishi Chemical Co., Ltd.), a silicate compound, was added dropwise over 2 hours. After dropping, stirring was continued for 6 hours, and then diluted with 34 g of isopropanol (abbreviated as “IPA” in the following table) to obtain a dispersion of specific particles.
From an image obtained by observing the dispersion with a scanning electron microscope (TEM), it was confirmed that core-shell particles (specific particles) composed of a polymer core and a shell of a silica component could be formed.
1.5 g of SNOWTEX (registered trademark) OS (pH 2.0 to 4.0, spherical, particle size 8 nm to 11 nm, solid content 20%, manufactured by Nissan Chemical Industries, Ltd.) which is a dispersion of metal oxide particles 48.5 g of isopropanol was added and stirred at room temperature (25 ° C.), and then mixed with 50 g of an isopropanol dispersion of the obtained specific particles to prepare the porous membrane composition 1 of Example 1.

The detail of each component shown below is as showing below. Each component may be abbreviated in Tables 1 to 3. In addition, the particle size of the following metal oxide particle shows a surface area average particle diameter.
(Polymer particles)
Neokrill (registered trademark) XK-30 (cationic acrylic particles, number average particle size 49 nm, solid content 45.5%, manufactured by DSM Neo Resins Co., Ltd.)
(Silicate compound: methyl silicate oligomer)
MKC silicate MS51 (SiO ₂ min 52%, Mitsubishi Chemical Co., Ltd.)
(Metal oxide particles: silica particles)
Snowtex (registered trademark) OXS (pH 2.0 to 4.0, spherical, particle size 4 nm to 6 nm, solid content 10%, Nissan Chemical Industries, Ltd.)
Snowtex (registered trademark) OS (pH 2.0 to 4.0, spherical, particle size 8 nm to 11 nm, solid content 20%, Nissan Chemical Industries, Ltd.)
Snowtex (registered trademark) O-40 (pH 2.0 to 4.0, spherical, particle size 20 nm to 25 nm, solid content 40%, Nissan Chemical Industries, Ltd.)
Snowtex (registered trademark) OL (pH 2.0 to 4.0, spherical, particle size 40 nm to 50 nm, solid content 20%, Nissan Chemical Industries, Ltd.)
Snowtex (registered trademark) OYL (pH 2.0 to 4.0, spherical, particle size 50 nm to 80 nm, solid content 20%, Nissan Chemical Industries, Ltd.)
Snowtex (registered trademark) OUP (pH 2.0 to 4.0, chain, primary particle size 10 nm to 20 nm, secondary particle size 40 nm to 100 nm, solid content 15%, Nissan Chemical Industries, Ltd.)
Organosilica sol IPA-ST (isopropanol dispersion, particle size 10-15 nm, solid content 30%, Nissan Chemical Industries, Ltd.)
(Metal oxide particles: Alumina particles)
Alumina sol AS-520 (pH 3-5, particle size 15 nm-30 nm, solid content 20%, Nissan Chemical Industries, Ltd.)

[Example 2]
[Preparation of Composition 2 for Forming Porous Film]
After mixing 9.7 g of water and 0.8 g of 10% acetic acid aqueous solution, 2.35 g of Neokryl XK-30 and 1.5 g of Snowtex OS were added and stirred at room temperature to obtain a mixture. To the obtained mixture, 3.15 g of MKC silicate MS51 was added dropwise over 2 hours. After dripping, stirring was continued for 6 hours, and then diluted with 82.5 g of isopropanol to prepare a porous membrane composition 2 of Example 2 as a dispersion of specific particles.

[Examples 3 to 8, Comparative Example 1, Comparative Example 2, Comparative Example 4, Comparative Example 5]
(Preparation of porous film forming composition)
Except that the content of silica particles and the content of isopropanol used in the preparation of the composition were changed as described in Tables 1 and 2 below, Examples 3 to 8 and Comparative Examples were made in the same manner as Example 2. The composition for forming a porous film of 1, Comparative Example 2, Comparative Example 4 and Comparative Example 5 was prepared.

[Comparative Example 3]
In Example 1, a porous film of Comparative Example 3 was prepared by mixing a composition containing Snowtex OS, isopropanol and the like according to the description in Table 2 without using MKC silicate MS51 which is a silicate compound. A composition for use was prepared.

[Examples 9 to 13, Comparative Example 7, Comparative Example 8]
Example 9 to Example 13, Comparative Example, except that the type and amount of metal oxide particles used in the preparation of the composition and the amount of isopropanol added were changed as shown in Table 3 below. 7 and the composition for forming a porous film of Comparative Example 8 were prepared.

[Preparation of porous membrane]
After apply | coating each obtained composition for porous membranes to alkali free glass OA-10G (Nippon Electric Glass Co., Ltd., thickness 7mm) using a spin coater at rotation speed 1000rpm (times / min), The composition layer was formed by heating in a 100 ° C. oven for 2 minutes. The obtained glass substrate having the composition layer was fired at 700 ° C. for 2 minutes in a muffle furnace to form a porous film on the glass substrate.

[Evaluation of porous membrane]
The obtained porous membrane was evaluated according to the following criteria. The results are shown in Tables 1 to 3 below.

<Refractive index>
The laminate in which the porous film was formed on the glass substrate was measured with an ellipsometer, and the refractive index at a wavelength of 633 nm was determined.

<Water contact angle>
Using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.), 1 μL of a water droplet was dropped on the surface of the porous membrane, and the static contact angle of the water droplet was measured.

<Antireflection>
Using a UV-visible infrared spectrophotometer (model number: UV3100PC, manufactured by Shimadzu Corporation), the transmission spectrum of the glass substrate having the porous film formed thereon was measured at a wavelength of 400 nm to 1100 nm.
The difference (ΔT) between the average transmittance (Tav) at a wavelength of 400 nm to 1100 nm of the obtained transmission spectrum and the average transmittance (T ₀ av) of the glass substrate not forming the porous film is expressed by the following formula (1 ). In addition, (DELTA) T shows that it is excellent in antireflection (AR) property, so that a numerical value is high. The evaluation item in the table is described as “AR property”.

ΔT = Tav−T ₀ av equation (1)

<Fingerprint wiping>
After attaching a fingerprint to the antireflection film, it was wiped five times with Bencot (registered trademark: non-woven wiper manufactured by Asahi Kasei Co., Ltd.) moistened with water, and the remaining fingerprint was visually observed.
A: Fingerprints disappeared B: Fingerprints remained slightly C: Fingerprints remained clearly, causing problems in practical use

<Tape peelability>
Nichiban cello tape (registered trademark) CT-24 (width 25 mm) was attached to the antireflection film, and the peel force (N) when peeled 180 ° using Tensilon was measured. It shows that tape peelability is so good that peeling force is small.
In addition, the content ratio of the “silica component” in the following Tables 1 to 3 represents the content ratio of the “silica component derived from the silicate compound contained in the composition”.

As shown in Tables 1 to 3, the porous membranes of the examples were excellent in all of antireflection properties, antifouling properties, and tape peelability. Further, from the comparison between Example 1 and Example 2, after preparing a mixture of polymer particles and metal oxide particles, a composition for forming a porous film obtained by adding a silicate compound to prepare specific particles It can be seen that the porous film, which is a fired product, has better antifouling properties and tape peelability.
On the other hand, Comparative Example 1 containing no metal oxide particles was inferior in antifouling properties. In Comparative Examples 2, 4, and 5, in which the content is outside the range defined by the composition in the present disclosure even though the polymer particles, the silica component derived from the silicate compound, and the metal oxide particles are included It was inferior to either prevention property or tape peelability. Moreover, the comparative example 3 using the polymer particle which does not have a silica coating layer was inferior to tape peelability. Further, Comparative Examples 7 and 8 in which the particle size of the silica particles, which are metal oxide particles, was too large, were insufficient in antifouling properties.

Claims (9)

Polymer particles;
A silica component derived from a silicate compound;
Metal oxide particles having a surface area average particle size of 1 nm to 30 nm;
A dispersion medium,
The content of the polymer particles is 28% by mass to 37% by mass with respect to the total solid content in the composition, and the content of the silica component derived from the silicate compound is 33% by mass with respect to the total solid content in the composition. ˜67% by mass, the content of the metal oxide particles is 5% by mass to 30% by mass with respect to the total solid content in the composition, and at least a part of the surface of the polymer particles is a silicate compound. A composition for forming a porous film coated with a silica component derived therefrom.   2. The composition for forming a porous film according to claim 1, wherein a surface area average particle diameter of the metal oxide particles is not more than one half of an average particle diameter of the polymer particles.   The composition for forming a porous film according to claim 1, wherein the metal oxide particles are silica particles.   The composition for forming a porous film according to any one of claims 1 to 3, wherein the polymer particles are cationic particles.   The composition for forming a porous film according to any one of claims 1 to 4, wherein the polymer particles are cationic (meth) acrylic particles. Mixing polymer particles and metal oxide particles having a surface area average particle diameter of 1 nm to 30 nm to prepare a mixture; and
Adding a silicate compound to the resulting mixture to obtain polymer particles having at least a portion of the surface coated with silica,
The manufacturing method of the composition for porous film formation of any one of Claims 1-5. A step of providing a porous film-forming composition layer by applying the porous film-forming composition according to any one of claims 1 to 5 on a substrate;
Firing the formed porous membrane-forming composition layer; and
The manufacturing method of the porous membrane containing this.   The laminated body which has the baked material of the composition for porous film formation of any one of Claims 1-5 on a base material.   A solar cell module provided with the laminated body of Claim 8.