JP6847243B2 - Coating composition, laminate and solar cell module, and method for manufacturing the laminate - Google Patents

Description

The present disclosure relates to a coating composition, a laminate and a solar cell module, and a method for producing the laminate.

In recent years, a coating composition for coating a thin layer having a thickness of several μm to several tens of nm by a coating method has been widely used in applications such as optical films, printing, and photolithography. Among the coating compositions, the aqueous coating composition uses a solvent containing water as a main component, so that the surface energy of the film formed by coating is low and the film is excellent in transparency. On the other hand, the coating composition containing an organic solvent as a main component has advantages such as low viscosity of the coating composition and low surface tension of the coating composition. Therefore, coating compositions using either water or an organic solvent as the solvent have been applied to various uses.

Specific applications of the coating composition include, for example, antireflection film, optical lens, optical filter, flattening film for thin film transistor (TFT) of various displays, dew condensation prevention film, antifouling film, surface protective film and the like. Can be applied to functional membranes. Among them, the antireflection film can be applied to, for example, a protective film for a solar cell module, a surveillance camera, a lighting device, a sign, etc., and in recent years, the usefulness of the antireflection film has attracted attention.

Since the windshield of the solar cell module is arranged on the outermost surface of the module, not only antireflection but also scratch resistance is required to be improved. In addition, in the process of assembling the solar cell module, a resin such as an ethylene-vinyl acetate copolymer (hereinafter abbreviated as "EVA") may be used as a sealing material when arranging the windshield. is there. In such a case, even if a substance such as a sealing material comes into contact with an undesired area of a hard surface such as a windshield surface, it also has antifouling property that enables easy removal (for example, peeling, wiping, etc.). Desired.

As a technique related to the above coating composition, for example, Japanese Patent Application Laid-Open No. 2016-1199 _{has a silica matrix precursor represented by highly hydrolyzable SiX 4} (X is a hydrolyzable group). , A coating composition that provides good scratch resistance is disclosed. Further, the antireflection property is improved by specifying the refractive index and the diameter of the pores of the coating composition.

Further, the coating composition described in Japanese Patent No. 4512250 discloses an example in which hydrogen silsesquioxane (hydrogenated trifunctional silane compound) is contained as a silica matrix precursor having high reactivity and low surface energy. It is said to have excellent scratch resistance and stain resistance.

However, in the coating composition described in JP-A-2016-1199, when the above silica matrix precursor is used, the surface energy thereof is high, so that the density of the matrix formed on the film surface is not sufficient. Therefore, when a resin such as EVA adheres to the surface of the coating film, the resin penetrates into the film and cannot be easily removed, resulting in deterioration of antifouling property.

Further, in Japanese Patent No. 4512250, when the coating liquid is coated so as to obtain a coating film having a film thickness suitable for obtaining good antireflection properties (for example, an average film thickness of 80 nm to 200 nm), hydrogen sill is used. Since sesquioxanes are likely to aggregate with each other and have poor wettability with respect to glass, uneven film thickness is likely to occur. Therefore, it is difficult to uniformly form an appropriate film thickness for antireflection, and good antireflection property cannot be obtained.

An object to be solved by one embodiment of the present invention is to provide a coating composition capable of obtaining a film having excellent antireflection, scratch resistance and antifouling property.
An object to be solved by another embodiment of the present invention is to provide a laminate having excellent antireflection, scratch resistance and antifouling property, and a method for producing the same.
An object to be solved by another embodiment of the present invention is to provide a solar cell module that exhibits excellent power generation performance.

Specific means for solving the problem include the following aspects.
<1> The polymer particles, the silane compound selected from the hydrolyzable silane compound represented by the following formula (1) and the partially hydrolyzed condensate of the above hydrolyzable silane compound, and the hydrogen bond term of the solubility parameter are 16 MPa ^{1. A coating composition containing / 2} or more of an organic solvent.
H-Si (OR ¹ ) ₃ formula (1)
In the formula (1), R ¹ independently represents an alkyl group having 1 to 3 carbon atoms.
<2> The coating composition according to <1>, further comprising a hydrolyzable silane compound represented by the following formula (2) and a partially hydrolyzed condensate of the hydrolyzable silane compound.
R ^3- Si (OR ² ) ₃ formula (2)
In the formula (2), R ² independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ³ is an alkyl group having 1 to 8 carbon atoms and an alkyl fluoride having 1 to 8 carbon atoms. Represents a group, an aryl group having 6 to 12 carbon atoms.

<3> The coating composition according to <1> or <2>, wherein the boiling point of the organic solvent is 50 ° C. or higher and lower than 200 ° C.
<4> The coating composition according to any one of <1> to <3>, wherein the hydrogen bond term of the solubility parameter is 16 ^{MPa 1/2} or more and ^{less than 22 MPa 1/2.}
<5> A silane compound selected from the hydrolyzable silane compound represented by the above formula (1) and the partially hydrolyzed condensate of the above hydrolyzable silane compound is contained in an amount of 50% by mass or more based on the total amount of the silane compound. The coating composition according to any one of 1> to <4>.
<6> The coating composition according to any one of <1> to <5>, which contains water and has a content of the organic solvent in an amount of 50% by mass or more based on the total mass of the solvent.
<7> The coating composition according to any one of <1> to <6>, wherein the solid content concentration is 1% by mass or more and 20% by mass or less with respect to the total mass of the coating composition.

<8> A laminate having a cured product of the coating composition according to any one of <1> to <7> on a base material.
<9> The laminate according to <8>, wherein the base material is a glass base material.
<10> The laminate according to <9>, wherein the glass base material has an uneven structure on the surface.
<11> A solar cell module including the laminate according to any one of <8> to <10>.
<12> A step of applying the coating composition according to any one of <1> to <7> onto a substrate with a roll coater to form a coating film, and drying the coating film formed by the coating. This is a method for producing a laminate, which comprises a step of firing a coating film after drying and a step of firing the coating film after drying.

According to one embodiment of the present invention, there is provided a coating composition capable of obtaining a film having excellent antireflection, scratch resistance and antifouling property.
According to another embodiment of the present invention, there is provided a laminate having excellent antireflection, scratch resistance and antifouling property, and a method for producing the same.
According to another embodiment of the present invention, there is provided a solar cell module that exhibits excellent power generation performance.

Hereinafter, the coating composition, the laminate and the method for producing the same, and the solar cell module of the present disclosure will be described in detail.

In the present specification, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value. In the numerical range described stepwise in the present specification, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. Further, in the numerical range described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the examples.
Further, in the present specification, the amount of each component in the composition is the sum of the plurality of substances present in the composition unless otherwise specified, when a plurality of substances corresponding to each component are present in the composition. Means quantity.

In addition, the term "process" in the present specification is not limited to an independent process, and even if it cannot be clearly distinguished from other processes, the term "process" will be used as long as the intended purpose of the process is achieved. included.

In the present disclosure, the "silica matrix" refers to a continuous phase of a cured product obtained by condensing a hydrolyzable silane compound or a partially hydrolyzed condensate of a hydrolyzable silane compound.

<Coating composition>
The coating composition of the present disclosure includes polymer particles, a hydrolyzable silane compound represented by the following formula (1), and a silane compound selected from a partially hydrolyzed condensate of the above hydrolyzable silane compound (hereinafter, "hydrogen" as a whole. (Also referred to as "hydrolyzed trifunctional silane compound" or "hydrolyzed trifunctional alkoxysilane compound"), and an organic solvent having a ^{solubility parameter hydrogen bond term (δH) of 16 MPa 1/2 or more.}

H-Si (OR ¹ ) ₃ formula (1)
In the formula (1), R ¹ independently represents an alkyl group having 1 to 3 carbon atoms.

Conventionally, the following studies have been made as techniques related to the above-mentioned coating composition.
For example, Japanese Patent Application Laid-Open No. 2016-1199 uses a tetrafunctional silane compound having high hydrolysis and condensation reactivity, so that the film to be formed has high hardness and excellent scratch resistance. On the other hand, since the tetrafunctional silane compound has a high polarity (dielectric constant), when it is used together with a pore-forming agent such as polymer particles, the surface uneven distribution in the coating film is insufficient and the surface is dense. Difficult to form a film. Therefore, when a resin such as EVA comes into contact with the film surface, the resin permeates into the inside of the film, and as a result, there is a problem that the antifouling property is deteriorated.

Japanese Patent No. 4512250 is expected to form a film using hydrogen silsesquioxane (hydrogenated trifunctional silane compound), and the formed film is expected to be excellent in scratch resistance and antifouling property. However, since a solvent having a low SP value hydrogen bond term (δH) is used as the solvent, highly polar hydrogen silsesquioxane cannot be sufficiently stabilized by solvation. Therefore, hydrogen silsesquioxanes are likely to aggregate with each other during drying of the coating film, and uneven film thickness is likely to occur. In addition, since the wettability to the hydrophilic glass substrate is poor, uneven film thickness is likely to occur. Therefore, the non-uniform film thickness reduces the antireflection property.

In the coating composition of the present disclosure, good film thickness uniformity can be obtained by using an organic solvent having a solubility parameter hydrogen bond term of 16 MPa ^1/2 or more and a hydrogenated trifunctional silane compound in combination, and antireflection property is improved. To do. That is, when the coating composition contains polymer particles and a hydrogenated trifunctional silane compound and ^{an organic solvent having a solubility parameter hydrogen bond term of 16 MPa 1/2} or more is used, the dispersion stability of the polymer particles and hydrogenation Both the solubility uniformity of the trifunctional silane compound can be improved. The reason for this is that the hydrogenated trifunctional silane compound and its hydrolyzate have higher polarity than the conventionally used alkylated trifunctional silane compound, so that the hydrogen bond term of the solubility parameter is 16 MPa ^1/2 or more. By using an organic solvent, it is stabilized by hydrogen bonding with the solvent, and it becomes easier to dissolve than the conventional alkylated trifunctional silane compound. As a result, aggregation of the silane compound is suppressed, the hydrogenated trifunctional silane compound and the polymer particles are uniformly dispersed in the film, and a coating film having a high uniform film thickness is formed. Similarly, an organic solvent having a solubility parameter hydrogen bond term of 16 MPa ^1/2 or more has good wettability to a hydrophilic glass substrate and does not cause uneven film thickness during coating.
The antireflection film has an appropriate film thickness for improving the antireflection property. Therefore, by improving the film thickness uniformity, the entire coating film has a target appropriate film thickness, and the antireflection property is improved.

Since the conventional tetrafunctional silane compound has a higher surface energy than the trifunctional silane compound, it is unlikely to be unevenly distributed on the surface of the coating film. Therefore, a dense layer of silica matrix cannot be formed on the surface, pores due to polymer particles are formed on the film surface, and the antifouling property is deteriorated.
However, low-polarity trifunctional silane compounds such as hydrogenated trifunctional silane compounds have lower surface energy than polymer particles and tend to be unevenly distributed on the film surface. As a result, a dense layer of silica matrix is formed on the film surface, and the antifouling property is improved.

The hydrogenated trifunctional silane compound exhibits the properties of the trifunctional silane compound before firing and tends to be unevenly distributed on the film surface. On the other hand, after firing, hydrogen in the molecule is desorbed to form the same Si- (OH) ₄ structure as the tetrafunctional silane compound, so that the hardness of the formed film is improved, which in turn improves the scratch resistance. be able to.

The trifunctional silane compound has a lower condensation reactivity than the tetrafunctional silane compound, the thickening of the coating composition over time is suppressed, and the stability over time in the liquid is improved. On the other hand, the tetrafunctional silane compound is superior to the trifunctional silane compound in terms of condensation reactivity, although the stability of the coating composition over time is slightly reduced.
Although the hydrogenated trifunctional silane compound of the present disclosure has lower reactivity than the tetrafunctional silane compound, it has an advantage that the stability over time is improved, and after firing, it is the same as when the tetrafunctional silane compound is used. Since the structure can be obtained, it also has an advantage that a high film hardness can be obtained.

Hereinafter, each component contained in the coating composition of the present disclosure will be described in detail.

(Polymer particles)
The coating composition of the present disclosure contains at least one of polymer particles as a pore-forming agent.
The polymer particles are particles that can be removed from the coating film formed by the coating composition, and are preferably particles that can be removed from the coating film by heat treatment. By removing the polymer particles from the coating film, pores are formed in the coating film after the heat treatment.
Examples of the particles that can be removed from the coating film by the heat treatment include particles that are removed by at least one of thermal decomposition and volatilization when the heat treatment is performed.

The thermal decomposition temperature of the polymer particles is preferably 300 ° C. to 800 ° C., more preferably 400 ° C. to 700 ° C.
The pyrolysis temperature means the temperature at the time when the mass reduction rate reaches 50% by mass in the thermogravimetric / differential thermal (TG / TDA) measurement.

The glass transition temperature (Tg) of the polymer particles is preferably 0 ° C. to 150 ° C., more preferably 30 ° C. to 100 ° C.
By setting the Tg to 150 ° C. or lower, the antifouling property of the obtained film is further improved. It is considered that this is because the hydrolyzable silane compound becomes more easily unevenly distributed on the film surface due to the increased fluidity of the coating composition.
By setting Tg to 0 ° C. or higher, the scratch resistance of the obtained film is further improved. It is considered that this is because the thermal decomposition temperature of the polymer particles can be set to 300 ° C. or higher, and pores having a uniform size can be obtained while maintaining high mechanical strength of the film.
The glass transition temperature is obtained from the DSC curve obtained by differential scanning calorimetry (DSC), and more specifically, it is described in "Supplementary" described in JIS K7121-1987 "Method for measuring transition temperature of plastics". It is determined by the outer glass transition start temperature.

In the present specification, "antifouling property" is evaluated by the tape adhesive residue property when cellophane tape (registered trademark) is attached. For example, in the field of a solar cell module, in an assembly process. When arranging the windshield, even if a resin such as ethylene-vinyl acetate copolymer (EVA) comes into contact with and adheres to an undesired region such as the windshield, it can be easily removed (for example, peeling, wiping, etc.). The properties can also be improved.

The polymer contained in the polymer particles is not particularly limited as long as polymer particles having a desired particle size can be obtained. As the polymer, a single monomer selected from the group consisting of (meth) acrylic acid ester-based monomer, styrene-based monomer, diene-based monomer, imide-based monomer, and amide-based monomer (hereinafter, also referred to as “specific monomer group”). Polymers or copolymers are preferred.
Further, from the viewpoint of the stability of the coating composition over time, it is preferable that the polymer constituting the polymer particles does not contain a functional group that reacts with a silanol group and condenses, such as a hydroxy group and a carboxy group.

Examples of the (meth) acrylic acid ester-based monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic. Isobutyl acid, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, nonyl (meth) acrylate, (meth) Decyl acrylate, dodecyl (meth) acrylate, phenyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, (Meta) Acrylic acid ethoxypropyl, diethylaminoethyl (meth) acrylate, dialkylaminoalkyl (meth) acrylate, glycidyl (meth) acrylate, ethylene glycol diacrylic acid ester, diethyl glycol diacrylic acid ester, triethylene glycol diacrylic acid ester , Polyacrylic acid ester of polyethylene glycol, Diacrylic acid ester of dipropylene glycol, Diacrylic acid ester of tripropylene glycol, Dimethacrylic acid ester of ethylene glycol, Dimethacrylic acid ester of diethylene glycol, Dimethacrylic acid ester of triethylene glycol, Polyethylene glycol Diacrylic acid ester of propylene glycol, dimethacrylic acid ester of propylene glycol, dimethacrylic acid ester of dipropylene glycol, dimethacrylic acid ester of tripropylene glycol and the like.

Styrene-based monomers include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, octylstyrene, fluorostyrene, chlorostyrene, bromostyrene, Examples thereof include dibromostyrene, chloromethylstyrene, nitrostyrene, acetylstyrene, methoxystyrene, α-methylstyrene, vinyltoluene, sodium p-styrenesulfonate and the like.

Examples of the diene-based monomer include butadiene, isoprene, cyclopentadiene, 1,3-pentadiene, dicyclopentadiene and the like.

Examples of the imide-based monomer include maleimide, N-methylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide, 6-aminohexyl succinate imide, 2-aminoethyl succinate imide and the like.

Examples of the amide-based monomer include acrylamide-based derivatives such as acrylamide and N-methylacrylamide, allylamine-based derivatives such as N, N-dimethylacrylamide, N, and N-dimethylaminopropylacrylamide, and aminostyrenes such as N-aminostyrene. Can be mentioned.

The polymer contained in the polymer particles is preferably a polymer having a crosslinked structure in order to obtain dispersibility in a solvent.
Polymer particles having a crosslinked structure can be obtained by polymerizing a crosslinkable monomer with an emulsifier described later. The cross-linking reactive monomer that can be used is not particularly limited, and for example, those having an unsaturated double bond in the molecule, those having a radically polymerizable double bond, and those having a reactive functional group in the molecule. (Specifically, carboxy group, hydroxy group, epoxy group, amino group, amide group, maleimide group, sulfonic acid group, phosphoric acid group, isocyanate group, alkoxy group, alkoxysilyl group and the like) can be mentioned. It is selected from one type or a combination thereof.

Among these, as the crosslink-reactive monomer, a monomer having a radically polymerizable double bond is preferable, and a (meth) acrylic acid ester-based monomer having a plurality of radically polymerizable double bonds in the molecule or a styrene type monomer is used. Monomers are more preferred.
Examples of the cross-linking reactive monomer include trimethyl propantriacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, decaethylene glycol dimethacrylate, pentadecaethylene glycol dimethacrylate, and 1,3-butylenedylated methacrylate. , Polyfunctional (meth) acrylates such as allyl methacrylate, trimethylolpropantrimethacrylate, pentaerythritol tetraacrylate; aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and derivatives thereof; N, N-divinylaniline; divinyl ether; Examples thereof include divinyl sulfide; divinyl sulfonic acid; polybutadiene; polyisoprene unsaturated polyester and the like.

The polymer particles are preferably nonionic polymer particles from the viewpoint of further improving scratch resistance and antifouling property. When the coating composition contains the nonionic polymer particles, the compatibility between the hydrolyzable silane compound and the nonionic polymer particles is improved, and the nonionic polymer particles are easily uniformly dispersed in the coating composition. As a result, when the film is formed by the coating composition, the distribution of pores existing in the film becomes uniform, and the hydrolyzable silane compound is unevenly distributed on the film surface, resulting in scratch resistance. And the antifouling property can be further improved.

The "nonionic polymer particles" are polymer particles synthesized by emulsion polymerization using a nonionic emulsifier and containing a structure derived from the nonionic emulsifier in the structure.
Here, the nonionic polymer particles are polymer particles that contain a structure derived from a nonionic emulsifier in their structure and substantially do not contain a structure derived from an anionic emulsifier or a structure derived from a cationic emulsifier. The term "substantially free" means that the ratio of the structure derived from the nonionic emulsifier to the total amount of the structure derived from the emulsifier is 99% by mass or more.
The proportion of the structure derived from the nonionic emulsifier can be calculated by analyzing the fragment of the polymer particle by a known method using pyrolysis GC-MS (gas chromatograph mass spectrometry).

The nonionic polymer particles are preferably self-dispersing particles. The self-dispersible particles refer to particles made of water and an alcohol-insoluble polymer that can be dispersed in an aqueous medium containing water and alcohol due to the hydrophilic portion of the polymer particles themselves. The dispersed state is an emulsified state (emulsion) in which water and an alcohol-insoluble polymer are dispersed in a liquid state in an aqueous medium, and a dispersed state (suspension) in which a water-insoluble polymer is dispersed in a solid state in an aqueous medium. It includes both states of.

Further, "water insoluble" means that the amount dissolved in 100 parts by mass (25 ° C.) of water is 5.0 parts by mass or less.

Since the nonionic polymer particles are self-dispersible particles, the nonionic polymer particles are likely to be uniformly dispersed in the obtained film, and for example, the coating composition does not contain an emulsifier or the content of the emulsifier is applied. Since it can be 1% by mass or less based on the total mass of the composition, it is excellent in scratch resistance and antifouling property.

As the nonionic emulsifier for synthesizing the nonionic polymer particles, various nonionic emulsifiers can be preferably used. The nonionic emulsifier is preferably a nonionic emulsifier having an ethylene oxide chain, and more preferably a nonionic reactive emulsifier having an ethylene oxide chain having a radically polymerizable double bond in the molecule. Thereby, a film having good pencil hardness can be obtained. The reason is not clear, but the good emulsion stability during polymerization makes the dispersion state of the polymer particles in the film uniform, and the distribution of pores becomes uniform, so that the distribution of pores is non-uniform. It is considered that the occurrence of local capillary force and cracks due to the above-mentioned condition is suppressed, and the scratch resistance of the obtained film is improved.

Specific examples of the nonionic emulsifier having an ethylene oxide chain include emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethyloxypropylene block copolymer, polyethylene glycol fatty acid ester, and polyoxyethylene sorbitan fatty acid ester. Be done.
Specifically, as the reactive emulsifier, polyethylene glycol mono (meth) acrylate, polyoxyethylene alkylphenol ether (meth) acrylate having various molecular weights (different number of moles of ethylene oxide added), monomaleic acid ester of polyoxyethylene glycol, and the like thereof. Derivatives, 2,3-dihydroxypropyl methacrylate, 2-hydroxyethyl acrylamide, and the like can be mentioned, and reactive emulsifiers having an ethylene oxide chain are preferable.
As the reactive emulsifier having an ethylene oxide chain, any emulsifier can be used as long as the number of chains is 1 or more as long as the ethylene oxide chain is present, but the most preferable is that the number of chains of the ethylene oxide chain is 2 or more and 30. Hereinafter, particularly preferable is an emulsifier of 3 or more and 15 or less. As the nonionic emulsifier having an ethylene oxide chain, at least one selected from these groups can be used.

As the nonionic emulsifier, a commercially available product may be used.
Examples of commercially available nonionic emulsifiers include "Neugen" series, "Aqualon" series (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), "Latemuru PD-420", "Latemuru PD-430", and "Latemuru PD". -450 ”and“ Emulsifier ”series (all manufactured by Kao Corporation) can be mentioned. Among them, reactions having ethylene oxide chains such as "Aqualon" series, "Latemuru PD-420", "Latemuru PD-430", "Latemuru PD-450" and having a radically polymerizable double bond in the molecule. Sexual emulsifiers are most preferably used.
Further, in the coating composition of the present disclosure, it is preferable not to use ionic polymer particles as the polymer particles, but ionic polymer particles can also be used in combination. When ionic polymer particles are mixed, the mixing amount is usually 30 parts by mass or less, preferably 10 parts by mass or less, and most preferably 3 parts by mass or less with respect to 100 parts by mass of the total amount of the polymer particles. Is.

The number average primary particle size of the polymer particles is preferably 60 nm or more and 200 nm or less. When the number average primary particle size of the polymer particles is within the above range, the antireflection property and the scratch resistance of the coating film become better. The scratch resistance can be evaluated by measuring the pencil hardness, and a film having a high pencil hardness is excellent in scratch resistance.
Specifically, when the number average primary particle diameter of the polymer particles is 60 nm or more, the matrix thickness between the pores in the film is secured, and the film strength is easily maintained. Therefore, deterioration of antireflection and scratch resistance due to insufficient vacancy caused by crushing of vacancy in the film is suppressed.
On the other hand, when the number average primary particle diameter of the polymer particles is 200 nm or less, for example, when the thickness of the film is 130 nm, the pore size does not become too large compared to the thickness of the film, so that the holes are opened on the film surface. It is difficult to form open pores that connect to the air layer. Therefore, a smooth surface having no pores on the film surface can be obtained, and the scratch resistance is improved.
Of the above, the number average primary particle diameter of the polymer particles is preferably 150 nm or less, more preferably 120 nm or less, from the viewpoint of stable pore formation. Further, the number average primary particle diameter of the polymer particles is more preferably 80 nm or more from the viewpoint of stable pore formation.
Further, the number average primary particle size of the polymer particles is preferably smaller than the film thickness of the target cured film.

The number average primary particle size of the polymer particles is a value measured by a dynamic light scattering method. Specifically, it was measured using Microtrac (Version 10.1.2-111BH) manufactured by Nikkiso Co., Ltd., and the value obtained as the cumulative 50% value (d50) of the number-equivalent particle size was the average number of polymer particles. The primary particle size.

The content of the polymer particles in the coating composition is preferably 1.0% by mass to 10% by mass, more preferably 1.5% by mass to 5.5% by mass, based on the total mass of the coating composition. More preferably, it is 3.0% by mass to 5.0% by mass.
When the content of the polymer particles is within the above range, it is suitable for further improving the antireflection property when the coating composition is used for forming the antireflection film.

The mass ratio of the content of the polymer particles in the coating composition to the total of the content of the silica particles and the silicon dioxide-equivalent content of the silane compound described later is 0.2 or more and 0.95 or less. It is preferably 0.2 or more and 0.6 or less, more preferably.
The mass ratio of the content of the polymer particles contributes to the improvement of the antireflection property.
When the mass ratio of the content of the polymer particles to the total of the content of the silica particles and the content of the silane compound in terms of silicon dioxide is 0.2 or more, pores in an amount suitable for antireflection are likely to be formed. , The porosity is increased and the antireflection property is improved. On the other hand, the mass ratio of the content of the polymer particles to the total of the content of the silica particles and the content of the silane compound in terms of silicon dioxide is preferably not too large from the viewpoint of antireflection. Specifically, the mass ratio of the content of the polymer particles to the total of the content of the silica particles and the content of the silane compound in terms of silicon dioxide is the content of the silica particles and the content of the silane compound in terms of silicon dioxide. It is preferably 0.95 or less with respect to the total of. When the mass ratio of the content of the polymer particles is 0.95 or less, it is difficult to form open pores that open on the film surface and connect with the air layer, so that a smooth surface having no pores on the film surface can be easily obtained. As a result, deterioration of antireflection property is suppressed.
Further, from the viewpoint of obtaining good scratch resistance in addition to antireflection property, the mass ratio of the preferable content of the polymer particles to the sum of the content of the silica particles and the content of the silane compound in terms of silicon dioxide is 0. It is 6 or less. When the number of pores in the film is small, the film strength increases, but when the mass ratio of the content of the polymer particles is 0.6 or less, the required film strength is maintained even if there are pores, and the film is scratch resistant. Deterioration is suppressed. That is, when the mass ratio of the content of the polymer particles is 0.6 or less, the antireflection property and the scratch resistance become better.
The scratch resistance can be evaluated by measuring the pencil hardness, and a film having a high pencil hardness is excellent in scratch resistance.

The mass ratio of the content of the polymer particles to the total of the content of the silica particles and the content of the silane compound in terms of silicon dioxide is (mass of polymer particles) / {(content of silica particles) + ( It is a value obtained by _{SiO 2} reduced mass of the silane compound)}.
The SiO ₂ reduced mass of the silane compound is a value calculated from the molecular weight of the silane compound by analyzing the structure of the target silane compound.

Of the above, the mass ratio of the content of the polymer particles to the total of the content of the silica particles and the content of the silane compound in terms of silicon dioxide improves the antireflection property when the antireflection film is formed. From the viewpoint, 0.4 to 0.6 is more preferable, and 0.5 to 0.6 is further preferable.
Furthermore, the content of the polymer particles is 3.0% by mass to 5.0% by mass with respect to the total mass of the coating composition, and the content of the silica particles and the silicon dioxide-equivalent content of the silane compound described later It is particularly preferable that the mass ratio of the content of the polymer particles to the sum of the above is 0.4 to 0.6.

(Silane compound)
The coating composition of the present disclosure is at least one of silane compounds selected from a hydrolyzable silane compound represented by the following formula (1) and a partially hydrolyzed condensate of a hydrolyzable silane compound represented by the formula (1). Contains.

H-Si (OR ¹ ) ₃ formula (1)
In the formula (1), R ¹ independently represents an alkyl group having 1 to 3 carbon atoms.

Examples of the alkyl group having 1 to 3 carbon atoms in R ¹ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group and the like.

In the present disclosure, a hydrogenated trifunctional silane compound and ^{an organic solvent having a hydrogen bond term (δH) of 16 MPa 1/2} or more as a solubility parameter are contained to improve the film thickness uniformity of the coating film.
That is, the hydrogenated trifunctional silane compound and its hydrolyzate have higher polarity than the conventionally used alkylated trifunctional silane compound. However, by using a solvent having a solubility parameter hydrogen bond term (δH) of 16 MPa ^1/2 or more, the hydrogenated trifunctional silane compound is stabilized by hydrogen bonding with the solvent, as compared with the conventional alkylated trifunctional silane compound. Also becomes easier to dissolve.
As a result, agglutination of the silane compound is suppressed, and the hydrogenated trifunctional silane compound that uniformly forms the film is dispersed in the film, so that a coating film having a uniform film thickness can be formed.

Further, by improving the film thickness uniformity, the entire coating film has an appropriate film thickness, and the antireflection property is improved.
Further, the hydrogenated trifunctional silane compound is excellent in uneven distribution in the coating process. In addition, hydrogen is desorbed during high-temperature firing and has the same Si- (OH) ₄ structure as the tetrafunctional silane compound, so it is also excellent in curing reactivity. As a result, both uneven distribution during coating and curing reactivity (scratch resistance) during firing can be achieved.

Examples of the hydride trifunctional silane compound include trimethoxysilane, triethoxysilane, trin-propoxysilane, trin-butoxysilane, trin-pentyloxysilane, trin-hexyloxysilane, and trin-heptyloxysilane. Examples thereof include silane and tri-n-octyloxysilane.

Among the hydrogenated trifunctional silane compounds, a compound in which R ¹ is an alkyl group having 1 to 2 carbon atoms is preferable. Specific examples thereof include trimethoxysilane and triethoxysilane.

As the hydrolyzable silane compound represented by the formula (1), a commercially available product on the market may be used. Examples of commercially available products include trimethoxysilane (hydrogenated trifunctional silane compound, manufactured by Tokyo Chemical Industry Co., Ltd.), triethoxysilane (hydrogenated trifunctional silane compound, manufactured by Tokyo Chemical Industry Co., Ltd.), and the like.

The coating composition of the present disclosure may contain water as a solvent, and a part of the hydrolyzable silane compound may be hydrolyzed and condensed. Therefore, the coating composition of the present disclosure contains a hydrolyzable silane compound represented by the formula (1) and a partially hydrolyzable condensate of the hydrolyzable silane compound represented by the formula (1). May be good.

Examples of the partially hydrolyzed condensate of the hydrolyzable silane compound represented by the formula (1) include hydrogen silsesquioxane oligomer. From the viewpoint of scratch resistance, hydrogen silsesquioxane oligomer is particularly preferable.

The hydrogen silsesquioxane oligomer may be obtained in the following synthetic example.
For example, 50.5 g of p-toluenesulfonic acid monohydrate, 151.5 g of 90% by mass sulfuric acid and 429.5 g of chlorobenzene are mixed in a flask, stirred and mixed at 250 rpm (round per minute), and the aqueous phase. A two-phase mixture consisting of and an organic phase is prepared. Further, 50.0 _{g of HSiCl 3} dissolved in 70.0 g of chlorobenzene is added over 50 minutes. After addition, the reaction mixture is stirred for 2 hours. The mixture was then placed in a separatory funnel and the aqueous phase was drained. The resulting organic phase is washed twice with 100 mL of 47% sulfuric acid and then twice with 100 mL of deionized water. _{About 20 g of calcium carbonate (CaCO 3} ) is added to this organic phase, and the mixture is stirred for 10 minutes to neutralize. Then, about 20 g of magnesium sulfate (sulfonyl ₄ ) is added, and the mixture is stirred for 10 minutes to dehydrate. The resulting solution is filtered and the solvent stripped. From the above, 17.9 g of soluble hydrogen silsesquioxane resin can be obtained. In this example, a yield of 91% is obtained.

In the present disclosure, a silane compound other than the above may be contained, and further, a trifunctional hydrolyzable silane compound represented by the following formula (2) and a partially hydrolyzed hydrolyzable silane compound represented by the formula (2) are partially hydrolyzed. It is preferable to contain a silane compound selected from the decomposition condensates (hereinafter, also generally referred to as "trifunctional silane compound" or "trifunctional alkoxysilane compound").
By adding the trifunctional silane compound that easily moves to the film surface and is unevenly distributed to the hydrogenated trifunctional silane compound, a more dense silica matrix is easily formed on the film surface, and the antifouling property can be further improved.
Further, by adding the trifunctional silane compound having a relatively low condensation reactivity to the hydrogenated trifunctional silane compound, the liquid time stability of the coating composition can be further improved. It is preferable that the content of the trifunctional silane compound does not exceed the content of the hydrogenated trifunctional silane from the viewpoint of scratch resistance.

R ^3- Si (OR ² ) ₃ formula (2)

In the formula (2), R ² independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ³ is an alkyl group having 1 to 8 carbon atoms and an alkyl fluoride having 1 to 8 carbon atoms. Represents a group, an aryl group having 6 to 12 carbon atoms.

When both R ² and R ³ represent an alkyl group having 1 to 8 carbon atoms, R ² and R ³ may be the same or different.

Examples of the alkyl group having 1 to 8 carbon atoms for R ^2, for example, a methyl group, an ethyl group, n- propyl, etc. i- propyl group.
Examples of the alkyl group having 1 to 8 carbon atoms in R ³ include a methyl group, an ethyl group, an n-propyl group, a butyl group and the like, and an alkyl group having 1 to 4 carbon atoms is preferable, and an alkyl group having 1 to 4 carbon atoms is preferable. Alkyl group is more preferable. The alkyl group in R ³ may be unsubstituted or substituted with a substituent. Examples of the substituent when the alkyl group is substituted include a halogen atom, an amino group, a hydroxy group, a mercapto group, an isocyanato group, a glycidoxy group, a (meth) acryloyloxy group, a ureido group and the like.
Examples of the alkyl fluoride group having 1 to 8 carbon atoms in R ³ include a fluoromethyl group, a fluoroethyl group, a trifluoropropyl group and the like.
Examples of the aryl group having 6 to 12 carbon atoms in R ³ include a phenyl group, a benzyl group, a tolyl group and the like.

Examples of the trifunctional alkoxysilane represented by "R ^3- Si (OR ² ) ₃ " include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, and n-propyltrimethoxysilane. , N-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, n-butyltrimethoxysilane, n-butyltriethoxysilane, n-pentyltrimethoxysilane, n-hexyltrimethoxysilane, n-hexyltri Ethoxysilane, n-heptyltrimethoxysilane, n-octyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxy Silane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, 3-aminopropyltrimethoxy Silane, 3-aminopropyltriethoxysilane, 2-hydroxyethyltrimethoxysilane, 2-hydroxyethyltriethoxysilane, 2-hydroxypropyltrimethoxysilane, 2-hydroxypropyltriethoxysilane, 3-hydroxypropyltrimethoxysilane, 3-Hydroxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-glycidoxypropyltrimethoxy Silane, 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 3- (meth) acrylicoxypropyl Trimethoxysilane, 3- (meth) acrylicoxypropyltriethoxysilane, 3- (meth) acryloyloxypropyltri n-propoxysilane, 3- (meth) acryloyloxypropyltriisopropoxysilane, 3-ureidopropyltrimethoxysilane , 3-ureidpropyltriethoxysilane and other trialkoxysilanes.

Among the trifunctional alkoxysilane compounds represented by the formula (2), a compound in which R ² is an alkyl group having 1 to 3 carbon atoms is preferable. Specifically, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, etc. It is a preferred compound.

The silane compound is also preferably an oligomer having a weight average molecular weight of 600 to 6000. When the weight average molecular weight is in the above range, it is easy to achieve both scratch resistance and antifouling property of the film.
Specifically, when the weight average molecular weight of the silane compound is 600 or more, the film obtained by the coating composition is more excellent in scratch resistance. It is considered that this is because the degree of condensation does not become too small when the film is formed by the coating composition. Further, when the weight average molecular weight of the silane compound is 6000 or less, the silane compound becomes more excellent in scratch resistance and antifouling property. It is considered that this is because the motility of the silane compound is easily maintained, and when the film is formed by the coating composition, the segregation amount of the silane compound on the film surface is maintained and the surface hardened layer is formed.

The weight average molecular weight of the silane compound is preferably 1600 to 6000, more preferably 1600 to 3000, in terms of achieving both scratch resistance and antifouling property and further improving the silane compound.

Weight average molecular weight refers to a value measured by gel permeation chromatography (GPC).
For the measurement by GPC, HLC (registered trademark) -8020GPC (Tosoh Corporation) was used as the measuring device, and TSKgel (registered trademark) Super Multipore HZ-H (4.6 mm ID x 15 cm, Tosoh Corporation) was used as the column. 3 bottles are used, and dimethylformamide is used as the eluent. The measurement conditions are a sample concentration of 0.45% by mass, a flow rate of 0.35 mL / min, a sample injection amount of 10 μL, and a measurement temperature of 40 ° C., using a differential refractive index (RI) detector. ..
The calibration curve is "Standard sample TSK standard, polystyrene": "F-40", "F-20", "F-4", "F-1", "A-5000", "A" of Tosoh Corporation. It is made from 8 samples of "-2500", "A-1000", and "n-propylbenzene".

In the present disclosure, the content of the hydrogenated trifunctional silane compound is preferably 50% by mass or more, more preferably 75% by mass or more, and particularly preferably 90% by mass or more, based on the total amount of the silane compound.

As the silane compound, a commercially available product on the market may be used.
Examples of commercially available products include KC-89S (R ² : methyl group, R ³ : methyl group, weight average molecular weight 770, manufactured by Shin-Etsu Chemical ^{Industry Co., Ltd.), KR-515 (R 2} : methyl group, R ³ : Methyl group, weight average molecular weight 1100, manufactured by Shin-Etsu Chemical Industry Co., Ltd., KR-500 (R ² : methyl group, R ³ : methyl group, weight average molecular weight 1200, manufactured by Shin-Etsu Chemical Industry Co., Ltd.), KBM-13 (R ² : Methyl group, R ³ : Methyl group, molecular weight 136.2, manufactured by Shin-Etsu Chemical Industry Co., Ltd.), KBM-103 (R ² : Methyl group, R ³ : phenyl group, molecular weight 198.3, Shin-Etsu Chemical Co., Ltd.) Industrial Co., Ltd.), KBM-3103C (R ² : Methyl group, R ³ : Decyl group, molecular weight 262.5, manufactured by Shin-Etsu Chemical Industry Co., Ltd.), KBE-04 (R ² : Ethyl group, R ³ : Ethoxy group, molecular weight 208.3, manufactured by Shin-Etsu Chemical Industry Co., Ltd.), X-40-9225 (R ² : methyl group, R ³ : methyl group, weight average molecular weight 5200, manufactured by Shin-Etsu Chemical Industry Co., Ltd.), X -40-9246 (R ² : Methyl group, R ³ : Methyl group, weight average molecular weight 3000, manufactured by Shin-Etsu Chemical Co., Ltd.), X-40-9250 (R ² : Methyl group, R ³ : Methyl group, weight average molecular weight 6300, Shin-Etsu Chemical Industry Co., Ltd.), Triethoxy (1H, 1H, 2H, 2H-nonafluorohexyl) Silane (R ² : Ethyl group, R ³ : Alkyl fluoride group, molecular weight 410.4, Tokyo Kasei Kogyo Co., Ltd. Made), etc.

The content of the silane compound in the present disclosure is more preferably 1% by mass to 10% by mass, further preferably 2% by mass to 8% by mass, and 3% by mass to 6% by mass with respect to the total mass of the coating composition. Is particularly preferable.
When the content of the silane compound is within the above range, the silica matrix is satisfactorily formed after firing, which is advantageous for the formation of a porous film having high hardness.

(solvent)
The coating composition of the present disclosure contains an organic solvent having a solubility parameter hydrogen bond term (δH) of 16 MPa ^{1/2 or more.} As a result, the above-mentioned hydrogenated trifunctional silane compound and the solvent form hydrogen bonds, the hydrogenated trifunctional silane compound is stabilized, the thickness unevenness of the film can be suppressed to a small value, and the film thickness uniformity can be further improved. ..

The hydrogen bond term (δH) of the above solubility parameter refers to the hydrogen bond term (δH) of the Hansen solubility parameter (SP value).

Examples of organic solvents having a hydrogen bond term (δH) with a solubility parameter of 16 MPa ^{1/2 or more include methanol (δH = 21.4 MPa 1/2} ), ethanol (δH = 18.3 MPa ^1/2 ), 1-. Alcohol-based solvents such as propanol (δH = 16.2 MPa ^1/2 ) and 2-propanol (δH = 16.2 MPa ^1/2 ); ethylene glycol (δH = 27.7 MPa ^1/2 ), diethylene glycol (δH = 22. 1 MPa ^1/2), triethylene glycol (δH = 19.2MPa ^1/2), glycol-based solvents such as ethylene glycol monomethyl ether (δH = 17.0MPa ^1/2); hydroxyacetone (δH = 17.7MPa ^{1 / 2} ), a ketone solvent such as acetoin (3-hydroxy-2-butanone; δH = 16.0 MPa ^1/2 ); and the like.

The hydrogen bond term (δH) of the Hansen solubility parameter indicates the solubility parameter calculated by Hansen, and is the Industrial Solvents Handbook (by Wesley L. Archer) and Hansen Solubility Parameters: A User's Handbook, Second Edition ( The value of the solubility parameter described in Charles M. Hansen) or the value determined by the calculation method is applied.
The hydrogen bond of the Hansen solubility parameter (delta] H), ^{16 MPa 1/2} or more ^22MPa less than ^1/2 are preferred.

The organic solvent in the present disclosure is not limited to the boiling point, but an organic solvent having a boiling point of 50 ° C. or higher and lower than 300 ° C. under normal temperature and pressure is preferable.
When the boiling point of the organic solvent is 50 ° C. or higher, excessive evaporation of the solvent from the coating film is suppressed, temperature uniformity in the surface of the substrate is improved, and film thickness uniformity is further improved. Further, when the boiling point of the organic solvent is less than 300 ° C., the residue of the organic solvent inside the film can be suppressed in the drying step, a more dense film is formed, and the scratch resistance is further improved.
Examples of organic solvents having a boiling point within the above range are methanol (boiling point 64.5 ° C.), ethanol (boiling point 78.3 ° C.), 2-propanol (boiling point 82.2 ° C.), hydroxyacetone (boiling point 145 ° C.). , 1-propanol (boiling point 97.0 ° C.), ethylene glycol (boiling point 197.3 ° C.), ethylene glycol monomethyl ether (boiling point 124 ° C.), acetoin (boiling point 144 ° C.).
Among the above, an organic solvent having a boiling point of 50 ° C. or higher and lower than 200 ° C. is more preferable.

Among the organic solvents, an alcohol solvent is preferable, monohydric alcohol is more preferable, methanol, ethanol and 2-propanol are more preferable, and 2-propanol is particularly preferable, from the viewpoint of dispersibility of the polymer particles.

The coating composition of the present disclosure preferably contains both water and an organic solvent, and more preferably contains water and 2-propanol from the viewpoint of solubility of the components used in the preparation of the coating composition.

The solvent preferably contains water. By containing water, it is suitable for dispersing polymer particles and hydrolyzing and dissolving the above-mentioned silane compound.

The water is preferably water that does not contain impurities or has a reduced content of impurities, and for example, deionized water is preferable.

When the coating composition contains water, the content of water in the coating composition is 0.5% by mass to the total mass of the coating composition from the viewpoint of further improving the scratch resistance of the obtained film. 20% by mass is preferable, 2% by mass to 15% by mass is more preferable, and 4% by mass to 10% by mass is further preferable.
When the water content is within the above range, it is considered that the silica matrix can be efficiently formed in the film obtained by the coating composition.

When the antireflection film is formed, it is preferable to contain water and an organic solvent as the solvent from the viewpoint of further improving the antireflection property of the film.

When water and an organic solvent are included as the solvent, the content of the organic solvent with respect to the total mass of the solvent is preferably 50% by mass or more.
When the content of the organic solvent is 50% by mass or more, the thickness unevenness of the film is suppressed to be smaller, and a film with higher uniformity can be easily obtained. This is because the amount of water present in the coating film is relatively small during the drying process during film formation, so that aggregation of silane compounds, which are not relatively high in water solubility, is suppressed, and segregation of the silica matrix and emptying are suppressed. This is thought to be because the uneven distribution of holes is suppressed.
As a result, the entire film has a thickness suitable for antireflection, and the antireflection property is effectively improved.
Of the above, the content of the organic solvent with respect to the total mass of the solvent is more preferably 60% by mass or more, further preferably 70% by mass or more, and particularly preferably 80% by mass or more. Further, since it is preferable to contain water from the viewpoint of maintaining the hydrolyzability of the silane compound, the content of the organic solvent is preferably 95% by mass or less, more preferably 90% by mass or less.

The organic solvent is an organic solvent in which polymer particles are dispersed, a hydrolyzable silane compound is dissolved, and the hydrogen bond term (δH) of the solubility parameter is 16 MPa ^1/2 or more.
In this case, the total content of water and the organic solvent with respect to the total mass of the coating composition is preferably 80% by mass to 99% by mass, more preferably 10% by mass to 98% by mass, and 92% by mass to 97% by mass. % Is more preferable.

(Other ingredients)
The coating composition of the present disclosure may contain other components in addition to the above-mentioned components, if necessary. Other components include silica particles, electrolytes, surfactants, thickeners, alkali metal silicates and the like.

-Silica particles-
The coating composition of the present disclosure preferably contains at least one of silica particles having a number average primary particle diameter of 2 nm or more and 15 nm or less. By containing the silica particles, the film hardness is increased and scratch resistance that is less likely to cause cracks can be obtained.

The coating composition of the present disclosure selectively contains silica particles having a small particle size having a number average primary particle size in a specific range. Since the coating composition contains silica particles having a small particle size with a number average primary particle diameter of 15 nm or less, the shrinkage stress generated by dehydration condensation of the silane compound is alleviated by the fine movement of the small size silica particles. Will be done. As a result, it is presumed that the generation of cracks that are likely to occur in large-sized particles can be suppressed, and the scratch resistance of the film can be improved. That is, when the number average primary particle diameter is 15 nm or less, the large movement of silica particles due to shrinkage stress is reduced, so that cracks are less likely to occur and the scratch resistance that is not improved even if the originally hard silica particles are used is effectively improved. Can be enhanced. It is considered that this is because the firing of the coating film causes a plurality of silica particles to be linked to form a particle linkage, and the hardness of the film is increased.
When the number average primary particle size is 2 nm or more, it can be easily obtained.

The number average primary particle size of the silica particles can be obtained from an image of a photograph taken by observing the dispersed silica particles with a transmission electron microscope.
Specifically, the projected area of 200 silica particles randomly extracted from the image of a photograph is measured, the equivalent circle diameter is obtained from the measured projected area, and the value of the obtained equivalent circle diameter is arithmetically averaged. The value obtained as a result is taken as the number average primary particle diameter of the silica particles.

As the silica particles, non-porous silica particles are preferable.
The "non-porous 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). It does not contain silica particles with a core-shell structure composed of.

When the coating film is fired, the non-porous silica particles are considered to change the state of the particles existing in the coating film before and after firing. Specifically, in the coating film before firing, a state in which each non-porous silica particle is aggregated such as a single particle (a state of being aggregated by Van der Waals force) is referred to as a single particle here. ), And it is considered that at least a part of the plurality of non-porous silica particles exists as a particle conjugate connected to each other in the coating film after firing.

As the silica particles, particles having any shape of sphere, chain, or beads may be used, or commercially available products on the market may be used.
Specific examples of commercially available spherical silica particles include "Snowtex (registered trademark) ST-OXS" manufactured by Nissan Chemical Industry Co., Ltd. (number average primary particle size: 4 nm to 6 nm, solid content: 10% by mass). "Snowtex (registered trademark) ST-O" (number average primary particle size: 10-15 nm, solid content: 20% by mass), "Fine Cataloid (registered trademark) F-120" manufactured by Japan Catalytic Chemical Industry Co., Ltd. (Number average primary particle size: 4-8 nm, solid content: 20% by mass), NALCO "NALCO (registered trademark) 8649" (number average primary particle size: 2 nm, solid content: 15% by mass), NALCO "NALCO (registered trademark) 1130" (number average primary particle size: 8 nm, solid content: 30% by mass) manufactured by NALCO, "NALCO (registered trademark) 1030" (number average primary particle size: 12 nm, solid) manufactured by NALCO. Minutes: 30% by mass), etc.

As a specific example of a commercially available chain silica particle, "Snowtex (registered trademark) ST-OUP" manufactured by Nissan Chemical Industry Co., Ltd. (number average primary particle size: 9-15 nm, solid content: 15% by mass) , "Snowtex (registered trademark) ST-UP" (number average primary particle size: 9-15 nm, solid content: 20% by mass), and the like.

As a specific example of a commercially available beaded silica particle, "Snowtex (registered trademark) PS-S" manufactured by Nissan Chemical Industry Co., Ltd. (number average primary particle size: 10-15 nm, solid content: 15% by mass) , "Snowtex (registered trademark) PS-SO" (number average primary particle size: 10-15 nm, solid content: 15% by mass), and the like.

The content of the silica particles in the coating composition is preferably 0.2% by mass to 40% by mass, more preferably 0.5% by mass to 30% by mass, and 1% by mass with respect to the total mass of the coating composition. % To 20% by mass is more preferable.
When the content of the silica particles is 0.2% by mass or more, a film quality having excellent scratch resistance can be easily obtained. Further, when the content of the silica particles is 40% by mass or less, the unevenness of the film surface is small, which is advantageous for forming a smooth planar film, and the antifouling property is more excellent.

-Electrolyte-
The coating composition of the present disclosure may contain an electrolyte. Examples of the electrolyte include compounds selected from acids, bases and salts. An electrolyte is a compound that dissociates into cations and anions when dissolved in water, which is a solvent.
Further, in the present disclosure, "acid" ^{refers to a substance that gives H +} , and "base" refers to a substance that receives ^{H +.} Among the acids, the acid satisfying pKa <0 is a strong acid.

As the acid, either a weak acid or a strong acid may be used as long as the pH can be maintained as described above. As the acid, for example, a weak acid such as acetic acid (pKa: 4.8); nitric acid (pKa: -1.4), phosphoric acid (pKa: 2.1), hydrochloric acid (pKa: -8.0), sulfuric acid ( Strong acids such as pKa: -3.0) can be mentioned.
Examples of the base include sodium hydroxide (pKa of conjugate acid: 15.7), potassium hydroxide (pKa of conjugate acid: 15.7), ammonia (pKa of conjugate acid: 9.3) and the like.
Examples of the salt include ammonium acetate, sodium acetate, potassium acetate, ammonium nitrate, sodium nitrate, potassium nitrate, ammonium sulfate, sodium sulfate, potassium sulfate, ammonium phosphate, sodium phosphate, potassium phosphate, ammonium chloride, sodium chloride and the like.
Further, instead of the salt, an acid and a base may be added. In this case, when the acid and the base are added, it is preferable that the pKa of the acid is 5.5 or less and the pKa of the conjugate acid which is the base is 8.5 or more.

As the salt, an ammonium salt and a metal salt are preferable, and the metal salt includes a salt of an alkali metal (for example, sodium, potassium, etc.) and a salt of an alkaline earth metal (for example, magnesium, calcium, etc.). Of these, in the metal salt, when the metal remains in the film after the coating film is formed and, for example, an antireflection layer is formed as a functional layer, the metal in the film affects the refractive index to improve the antireflection property. Ammonium salts are preferred in that they may be reduced.
Therefore, as the salt, an ammonium salt of an acid selected from a weak acid and a strong acid is more preferable, and ammonium acetate, ammonium nitrate, ammonium sulfate, ammonium phosphate, ammonium chloride and the like are further preferable.

The content of the electrolyte selected from the acid, base and salt is preferably 0.001 mol / L to 0.5 mol / L, preferably 0.005 mol / L to 0.4 mol / L, as the molar concentration in the coating composition. More preferably, 0.01 mol / L to 0.3 mol / L is further preferable.

-Surfactant-
The coating composition can contain a surfactant. By containing a surfactant, it is effective in improving the wettability of the coating composition to the substrate.
Examples of the surfactant include an acetylene-based nonionic surfactant, a polyol-based nonionic surfactant, and the like. Further, as the surfactant, a commercially available product on the market may be used, for example, Orfin series manufactured by Nissin Chemical Industry Co., Ltd. (for example, Orfin EXP.4200, Orfin EXP.4123, etc.), Dow Chemical Co., Ltd. TRITON BG-10 manufactured by Kao Corporation, My Doll series manufactured by Kao Corporation (for example, My Doll 10, My Doll 12, etc.) and the like can be used.

-Thickener-
The coating composition can contain a thickener. By including a thickener, the viscosity of the coating composition can be adjusted.
Examples of the thickener include polyether, urethane-modified polyether, polyacrylic acid, polyacrylic sulfonate, polyvinyl alcohol, polysaccharide and the like. Of these, polyethers, modified polyacrylic sulfonates, and polyvinyl alcohols are preferable. Commercially available products marketed as thickeners may be used, and examples of the commercially available products include SN thickener 601 (polyether), SN thickener 615 (modified polyacrylic sulfonate), and Jun Wako. Examples thereof include polyvinyl alcohol manufactured by Yakuhin Kogyo Co., Ltd. (degree of polymerization: about 1,000 to 2,000).
The content of the thickener is preferably about 0.01% by mass to 5.0% by mass with respect to the total mass of the coating composition.

-Alkali metal silicate-
The coating composition may contain an alkali metal silicate.
By containing the alkali metal silicate, both antireflection property and scratch resistance can be improved. The alkali metal silicate refers to an alkali metal salt of silicic acid, and an alkali metal silicate represented by the following formula A is preferable.
M ₂ O · nSiO ₂ ... Formula A

In formula A, M represents an alkali metal. Examples of the alkali metal include lithium (Li), sodium (Na), potassium (K), cesium (Cs) and the like. As the alkali metal represented by M, Li or K is preferable. By selecting Li or K as the alkali metal, the scratch resistance is further improved as compared with Na.
In formula A, n represents the molar ratio of alkali metal silicates. From the viewpoint of crosslinkability, n is preferably a compound of 5.0 or less.
If the molar ratio n of the alkali metal silicate is an appropriate value, it is considered that cross-linking is likely to occur. Therefore, when M is Li, it is considered that by selecting a compound satisfying n ≦ 5.0, the alkali metal silicate is easily crosslinked with the silica particles, and the scratch resistance is further improved. When the alkali metal represented by M is Li, n is more preferably 3.0 or more.

Other components can be contained within a range that does not significantly impair the effects of the embodiments of the present disclosure.

~ Solid content concentration ~
The coating composition of the present disclosure can be suitably used, for example, for forming an antireflection film having excellent antireflection properties.
For the formation of the antireflection film, the solid content concentration is preferably 1% by mass or more and 20% by mass or less with respect to the total mass of the coating composition from the viewpoint of further improving the antireflection property of the film.
When the solid content concentration is 1% by mass or more, the coating composition does not flow too easily and does not easily accumulate in the recesses on the base material, so that uneven thickness of the film is unlikely to occur. Further, when the solid content concentration is 20% by mass or less, the film is less likely to have uneven thickness because it is satisfactorily wetted and spread on the coating roll at the time of roll coating, for example. Therefore, when the solid content concentration of the coating composition is within the above range, the coating film of the coating composition easily follows the coating surface of the base material, and a film having small thickness unevenness and high uniformity can be easily obtained. As a result, the entire film has a thickness suitable for antireflection, and the antireflection property is effectively improved.
Of the above, the solid content concentration is more preferably 2% by mass to 10% by mass, further preferably 2% by mass to 6% by mass.
The solid content concentration in the coating composition can be adjusted by the content of the solvent.
The solid content concentration in the present disclosure refers to the ratio of the mass of the coating composition excluding the solvent (for example, water and an organic solvent) to the total mass of the coating composition.

The coating composition of the present disclosure contains small-sized silica particles and a trifunctional silane compound as described above, and is suitable for forming, for example, an antireflection film which is a cured product of the coating composition. Can be used. In the antireflection film using the coating composition of the present disclosure, a film having an appropriate refractive index is formed with a highly uniform thickness in which the occurrence of thickness unevenness is suppressed, and the surface is smooth and has high hardness. Therefore, it has excellent antireflection properties, and also has excellent scratch resistance and antifouling properties.

An antireflection film will be described as an example as a cured product of the coating composition of the present disclosure.
The coating composition of the present disclosure can be suitably used for coating formation of a cured film of a laminate having a base material having an uneven structure on the surface and a cured film. For example, the windshield mounted on the solar cell module has an antireflection film on the glass base material for reducing the reflection of sunlight, and the surface of the glass base material is provided with antiglare property. An uneven structure is provided for the purpose.

The antireflection property of the antireflection film is indicated by the following change in average reflectance (ΔR).
In the antireflection film according to the present disclosure, the numerical value of ΔR is a positive value.
Specifically, the reflectance of a laminate in which an antireflection film is formed on a substrate by an ultraviolet visible infrared spectrophotometer (model number: UV3100PC, manufactured by Shimadzu Corporation) in light having a wavelength of 400 nm to 1,100 nm. (%) Is measured using an integrating sphere. When measuring the reflectance, a black tape (model number: SPV-202) is applied to the front surface of the base material, which is the back surface, in order to suppress reflection on the back surface of the laminate (the surface on the side where the antireflection film of the base material is not formed). , Made by Nitto Denko). Then, the reflectance of each wavelength at the measured wavelength 400Nm～1,100nm, the average reflectance of the stack; calculating the ^{(R AV} units%). Similarly, the reflectance (%) of the base material on which the antireflection film is not formed is measured in light having a wavelength of 400 nm to 1,100 nm. ^{Then, the average reflectance (R 0AV} ; unit%) of the base material is calculated from the measured reflectance of each wavelength in the measured wavelengths of 400 nm to 1,100 nm.
Then, the average reflectance R ^AV, from R ^0AV average reflectivity change to the substrate on which the antireflection film is not formed ([Delta] R; unit:%) is calculated according to the following formula (a).
ΔR = R ^0AV − R ^AV equation (a)
ΔR indicates that the positive value and the larger the value, the better the antireflection (AR) property.

The reflectance can be measured by using a spectrophotometer with an integrating sphere. In the present disclosure, an ultraviolet-visible-infrared spectrophotometer (model number: UV3100PC, manufactured by Shimadzu Corporation) is used as a measuring device, and the reflectance in light having a wavelength of 400 nm to 1,100 nm is measured using an integrating sphere, and each of them is measured. The value obtained by arithmetically averaging the reflectance values at the wavelengths of is adopted as the average reflectance.

The ΔR of the antireflection film is preferably 2.3% or more, more preferably 2.6% or more, from the viewpoint of antireflection.

The average film thickness of the antireflection film can be in the range of 50 nm to 250 nm from the viewpoint of antireflection. Of these, 80 nm to 200 nm is preferable from the viewpoint of antireflection.
For the average film thickness, the antireflection film is cut in parallel with the film surface, the cut surface is observed at 10 points with a scanning electron microscope (SEM), and the film at each observation point is observed from 10 SEM images. It is obtained by measuring the thickness and averaging the 10 measured values (thicknesses) obtained. When the antireflection film is formed on the base material, the antireflection film is cut together with the base material in a direction orthogonal to the surface of the base material to perform the above observation. As the base material, a base material used for producing a laminate described later can be used.

<Laminate and its manufacturing method>
The laminate of the present disclosure has a cured product of the above-mentioned coating composition of the present disclosure on a base material.
Since the above-mentioned coating composition of the present disclosure is used, the side of the base material having a cured product has a plurality of pores inside the film, has high film thickness uniformity and smoothness, and has high hardness. have. As a result, it exhibits good antireflection properties and is excellent in antifouling property and scratch resistance. The laminate of the present disclosure is suitable as an antireflection material.

Examples of the base material include a base material such as glass, resin, metal, ceramic, or a composite material in which at least one selected from glass, resin, metal, and ceramic is composited. A preferred substrate is a glass substrate.
The thickness of the base material is not particularly limited and may be appropriately selected depending on the purpose, application and the like.

Among the base materials (preferably glass base materials) in the present disclosure, the surface is uneven from the viewpoint of more effectively exhibiting the effects of the present disclosure, particularly antireflection and antifouling properties, and imparting antiglare properties. It is preferably a base material having a structure.
The base material having an uneven structure refers to a base material having an arithmetic average roughness Ra of the surface of 0.1 μm to 1.0 μm. By laminating the coating film on the base material in which Ra is in this range, a laminated body having antiglare properties and functions such as antireflection is formed. Ra is more preferably 0.2 μm to 0.7 μm in order to impart functions such as antiglare and antireflection.
The arithmetic average roughness Ra is a value measured in accordance with JIS-B0601 using a surface roughness meter (model number: Handy Surf E-35B, manufactured by Tokyo Seimitsu Co., Ltd.).

The thickness of the cured product in the laminate can be in the range of 50 nm to 800 nm. For example, when used for antireflection applications, 50 nm to 250 nm is preferable, 80 nm to 200 nm is more preferable, and 120 nm to 140 nm is particularly preferable. preferable.
When the thickness of the cured product is 50 nm or more, the uniformity of the thickness of the coating film is excellent. Further, when the thickness of the cured product is 800 nm or less, the crack resistance becomes good, and the coatability can be kept good even when the solid content is high (for example, 20% by mass or more).
Further, by setting the thickness of the cured product in the range of 120 nm to 140 nm, the maximum antireflection effect can be obtained particularly in the vicinity of 600 nm where the solar spectrum intensity peaks.

~ Manufacturing method of laminated body ~
Next, a method for producing the laminate of the present disclosure will be described.
The method for producing a laminate of the present disclosure is also referred to as a step of applying the above-described coating composition of the present disclosure on a base material with a roll coater to form a coating film (hereinafter, also referred to as a “coating film forming step”. ), A step of drying the coating film (hereinafter, also referred to as a “drying step”), and a step of firing the dried coating film (hereinafter, also referred to as a “burning step”). In addition to the above steps, the method for producing a laminate of the present disclosure may further include other steps such as a cleaning step, a surface treatment step, and a cooling step, if necessary.

Since the above-mentioned coating composition is used in the method for producing a laminate of the present disclosure, a laminate having excellent antireflection properties, scratch resistance and antifouling properties can be obtained regardless of the surface condition of the base material. Be done.

-Coating film forming process-
In the coating film forming step, the coating composition of the present disclosure described above is applied onto a substrate by a roll coater to form a coating film.

In the coating film forming step, as described above, the present disclosure includes a specific electrolyte, polymer particles, and a hydrolyzable silane compound so as to suppress charging during coating and suppress the occurrence of uneven thickness of the coating film. Since the coating composition of the above is used, at least the film formed through the drying step and the firing step described later is suppressed from causing bright spot-like failure, and when it is an antireflection film, it has excellent antireflection property. It becomes. In addition, the film is also excellent in scratch resistance and antifouling property.

The coating amount of the coating composition is not particularly limited, and can be appropriately set in consideration of operability and the like according to the concentration of the solid content in the coating composition, the desired film thickness, and the like. The coating amount of the coating composition ^is preferably ^{0.01mL / m 2 ~30mL / m 2} , more preferably ^{0.1mL / m 2 ~20mL / m 2} , 1mL / m 2 ~15mL / It is more preferably m ^2. When the coating amount of the coating composition is within the above range, the coating accuracy is good and a film having more excellent antireflection property can be formed.

In the method for producing a laminate of the present disclosure, a roll coater is used for coating in the coating film forming step. When a film is formed using a roll coater, non-uniformity of the coating film tends to occur on the surface of the base material. However, in the present disclosure, by using the above-mentioned coating composition, a uniform coating film can be obtained. It is easy to form and the thickness variation can be suppressed to a small extent.
In particular, when the surface material of the roll for applying the coating composition to the surface of the base material (that is, the coating roll) is rubber, non-uniformity of the coating film tends to occur.
The rubber is, for example, ethylene propylene diene rubber (EPDM).

As the base material, any base material such as glass, resin, metal, ceramic, or a composite material obtained by combining at least one selected from glass, resin, metal, and ceramic can be selected.
Regardless of which base material is used, the effect of the method for producing the laminate of the present disclosure is expected, but since the coating roll on which the coating composition is applied is most likely to interact with the base material, the base material can be used. A glass base material is preferable because the effect is further exhibited.

When a glass substrate is used, the condensation of hydroxy groups occurs not only between the hydroxy groups of the hydrolyzable silane compound but also between the hydroxyl groups of the hydrolyzable silane compound and the hydroxyl groups on the glass surface. It is possible to form a coating film having excellent adhesion to the base material.

Among the base materials, when a base material having an uneven structure on the surface is used, the effect of the method for producing a laminate of the present disclosure is further exhibited. The base material having an uneven structure is as described above.

-Drying process-
In the drying step, the coating film formed in the coating film forming step is dried.
In the drying step, it is preferable that the coating film is fixed on the substrate by removing the solvent in the coating composition.
By removing the solvent in the coating composition, a dense film is formed. When the coating composition contains inorganic particles such as silica particles, the inorganic particles are densely arranged in the film to form a denser film. It is considered that excellent scratch resistance can be obtained by making the film dense and increasing the hardness. Further, it is considered that the film becomes dense and the film surface becomes smooth, so that dirt is less likely to adhere and the film surface is excellent in antifouling property.

The coating film may be dried at room temperature (25 ° C.) or by using a heating device.
As the heating device, any known heating device can be used without particular limitation as long as it can be heated to a target temperature. As the heating device, in addition to an oven, an electric furnace, etc., a heating device originally manufactured according to the production line can be used.

The coating film may be dried by heating the coating film at an atmospheric temperature of 40 ° C. to 200 ° C. using, for example, the above-mentioned heating device. When the coating film is dried by heating, the heating time can be, for example, about 1 minute to 30 minutes.
As the drying conditions for the coating film, it is preferable to heat the coating film at an atmospheric temperature of 40 ° C. to 200 ° C. for 1 minute to 10 minutes, and to heat the coating film at an atmospheric temperature of 100 ° C. to 180 ° C. for 1 minute to 5 minutes. The conditions are more preferred.

The average film thickness of the coating film after drying can be in the range of 50 nm or more, preferably in the range of 80 nm to 200 nm. When the average film thickness is 50 nm or more, the antireflection property of the film is excellent, and when the average film thickness is 80 nm to 200 nm, the antireflection property is excellent. The method for measuring the average film thickness is as described above.

-Baking process-
In the firing step, the coating film that has undergone the drying step is fired to obtain a cured film.
In the firing step, it is preferable to fire at an atmospheric temperature of 400 ° C. to 800 ° C. By firing the dried coating film at an atmospheric temperature of 400 ° C. to 800 ° C., the hardness of the dense film formed in the drying step is further increased, and the scratch resistance is further improved. Further, since at least a part of the organic components in the coating film, particularly the polymer particles, are thermally decomposed and disappeared by firing, voids of an arbitrary size are partially formed in the coating film after firing, and the antireflection property is obtained. Can be effectively improved.

Further, the hydrogenated trifunctional silane compound described above has the same Si− (OH) ₄ structure as the tetrafunctional silane compound due to desorption of hydrogen during high temperature firing. As a result, it is excellent in uneven distribution as a hydrogenated trifunctional silane compound at the time of coating and excellent in scratch resistance as a tetrafunctional silane compound at the time of firing, and both can be compatible.

The coating film can be fired using a heating device. As the heating device, any known heating device can be used without particular limitation as long as it can be heated to a target temperature. As the heating device, in addition to an electric furnace or the like, a firing device originally manufactured according to the production line can be used.
The firing temperature (atmospheric temperature) of the coating film is more preferably 450 ° C. or higher and 800 ° C. or lower, further preferably 500 ° C. or higher and 800 ° C. or lower, and particularly preferably 600 ° C. or higher and 800 ° C. or lower. The firing time is preferably 1 minute to 10 minutes, more preferably 1 minute to 5 minutes.

-Other processes-
If necessary, the method for producing a laminate of the present disclosure may include steps other than the above steps. Examples of other steps include a cleaning step, a surface treatment step, a cooling step, and the like.

By using the above-mentioned coating composition of the present disclosure, it is possible to form a porous film which is a cured product of the above-mentioned coating composition of the present disclosure. Further, in the above-mentioned laminate of the present disclosure and the method for producing the same, a laminate having a porous film which is a cured product of the above-mentioned coating composition of the present disclosure can be produced.
The porous film of the present disclosure is a silane compound selected from a trifunctional hydrolyzable silane compound represented by the following formula (1) and a partially hydrolyzed condensate of the hydrolyzable silane compound represented by the formula (1). It is a film containing a silica matrix which is a cured product of the above and, if necessary, silica particles, and has isolated pores inside the film excluding the surface.
H-Si (OR ¹ ) ₃ formula (1)
In the formula (1), R ¹ independently represents an alkyl group having 1 to 3 carbon atoms.
The details of the formula (1) are as described above, and the preferred embodiment is also the same. The details of the silica particles and the silane compound are as described above, and the preferred embodiments are also the same.

In the coating composition of the present disclosure, by using the hydrogenated trifunctional silane compound, hydrogen in the molecule is desorbed after firing, while it easily moves to the film surface as a trifunctional silane compound and is unevenly distributed before firing. Since it has the same Si- (OH) ₄ structure as the tetrafunctional silane compound, the formed porous film has high hardness and excellent scratch resistance.

"Having isolated pores inside the membrane excluding the surface" means that the inside of the membrane of the porous membrane has a plurality of isolated pores (isolated pores) that are not connected to each other, and the surface of the membrane is formed by the surface of the membrane. It means that there are no open pores having a diameter of 5 nm or more. That is, it is shown that the pores formed by firing are opened on the membrane surface because the polymer particles are present on the membrane surface, and there is no region in which the inside of the opened pores and the air layer are connected. ..
It should be noted that "there is no open pores to open on the surface of the film" can be confirmed by observing the surface of the film with a scanning electron microscope.

That is, the silica matrix is a cured product (calcined product) obtained by calcining the silane compound contained in the above-mentioned coating composition. After firing, the polymer particles contained in the coating composition disappear to form pores, and the plurality of pores are partitioned by a silica matrix. The silica matrix contains silica particles as needed.
As a result, the porous membrane has a porous structure having a plurality of pores, but as described above, the hydrogenated trifunctional silane compound has the same curing action as when the tetrafunctional silane compound is used, which is good. Has a high hardness and improves scratch resistance. Further, when silica particles are contained, the hardness is further increased, and the scratch resistance becomes more excellent.
Since the hydrogenated trifunctional silane compound contained in the film before firing is a trifunctional compound, a dense silica matrix layer is provided on the film surface by firing. As a result, it is also excellent in antireflection and antifouling properties.

When the porous film has silica particles, the mass ratio of the silica matrix to the silica particles is preferably 2.0 or more.

The thickness of the porous membrane is not particularly limited and can be in the range of 50 nm to 800 nm. When the porous film is used as, for example, an antireflection film, 50 nm to 250 nm is preferable, 80 nm to 200 nm is more preferable, and 120 nm to 140 nm is particularly preferable.
When the thickness of the porous membrane is 50 nm or more, the uniformity of the thickness of the membrane is excellent. Further, when the thickness of the porous film is 800 nm or less, the crack resistance becomes good.

<Solar cell module>
The solar cell module of the present disclosure includes the above-mentioned laminate of the present disclosure.
The laminate in the present disclosure may be a windshield or the like mounted on a solar cell module. In this case, the solar cell module includes a laminate according to the present disclosure, that is, a laminate having a base material and an antireflection film according to the present disclosure.

In the solar cell module, the solar cell element that converts the light energy of sunlight into electric energy is arranged on the side where sunlight is incident, and the laminate according to the present disclosure and the back sheet for solar cells represented by a polyester film. It may be configured by arranging it between and. The laminate according to the present disclosure and the back sheet for a solar cell such as a polyester film are sealed with a sealing material typified by a resin such as an ethylene-vinyl acetate copolymer.
Since the solar cell module includes the above-mentioned laminate having the antireflection film, it is excellent in antireflection property, antifouling property and scratch resistance, so that the film surface is soiled and scratched when used for a long period of time. It is considered that the decrease in light transmittance due to this is suppressed and the power generation efficiency is excellent.
The solar cell module according to the present disclosure preferably includes the laminate according to the present disclosure in the outermost layer of the solar cell module. That is, it is preferable that the outermost layer of the solar cell module according to the present disclosure is an antireflection film. In the solar cell module of the present disclosure, even if the outermost layer is an antireflection film, the antireflection film according to the present disclosure has antifouling property that can easily remove a resin such as a sealing material, and thus is used in an assembly process. Excellent manufacturing efficiency can be obtained.

Members other than the laminate and the back sheet in the solar cell module are described in detail in, for example, "Solar power generation system constituent materials" (supervised by Eiichi Sugimoto, published by Kogyo Chosakai Co., Ltd. in 2008). The solar cell module preferably has a laminate according to the present disclosure on the side where sunlight is incident, and there is no limitation on the configuration other than the laminate according to the present disclosure.

The base material of the solar cell module arranged on the side where sunlight is incident is preferably a laminated body according to the present disclosure.

The solar cell element used in the solar cell module is not particularly limited. Solar cell modules include silicon-based solar cell elements such as single crystal silicon, polycrystalline silicon, and amorphous silicon, and III-V such as copper-indium-gallium-selenium, copper-indium-selenium, cadmium-tellu, and gallium-arsenic. Any known solar cell element such as a group or II-VI compound semiconductor-based solar cell element can be applied.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist of the present invention is not exceeded.

-Synthesis of polymer particles 1-
The mixed solution having the following composition was emulsified by stirring at 10,000 rpm for 5 minutes using a homogenizer while cooling to obtain 64.8 parts by mass of the emulsified solution.
<Composition of mixed solution>
Ion-exchanged water: 35 parts by mass Methyl methacrylate: 13.8 parts by mass n-butyl acrylate: 13.8 parts by mass methoxypolyethylene glycol methacrylate (n = 9): 0.6 parts by mass Diethylene glycol dimethacrylate: 0.6 parts by mass Ethylene oxide Nonionic reactive emulsifier having a chain: 0.4 parts by mass (trade name: Latemul PD-450 (main component: polyoxyalkylene alkenyl ether), manufactured by Kao Co., Ltd.)
Polymerization initiator (trade name: V-65, manufactured by Wako Pure Chemical Industries, Ltd.): 0.6 parts by mass

On the other hand, a reactor equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen gas blowing tube, a nonionic reactive emulsifier having 35 parts by mass of ion-exchanged water and an ethylene oxide chain (trade name: Latemul PD-450 (main component)). : Polyoxyalkylene alkenyl ether), manufactured by Kao Co., Ltd.) 0.2 parts by mass was added and the temperature was raised to 65 ° C., followed by nitrogen substitution. The emulsion was uniformly dropleted over 3 hours while maintaining 65 ° C. under a nitrogen atmosphere, and further reacted at 65 ° C. for 2 hours.
After completion of the reaction, the mixture was cooled to obtain an aqueous emulsion of polymer particles 1.
The aqueous emulsion had a solid content concentration of 30% by mass and an average primary particle size of the polymer particles 1 of 100 nm.

(Example 1)
-Preparation of coating composition-
2.5 parts by mass of the above aqueous emulsion (polymer particles 1), 4.0 parts by mass of trimethoxysilane (hydrotrifunctional silane compound, active ingredient concentration 100% by mass, manufactured by Tokyo Kasei Kogyo Co., Ltd.), and an acetic acid aqueous solution. (Made by Wako Pure Chemical Industries, Ltd., diluted to 10% by mass with water) 0.5 parts by mass, 4.7 parts by mass of water, and Tokuso IPA (2-propanol, manufactured by Tokuyama Co., Ltd.) 90 A coating composition was prepared by mixing with 7. parts by mass and stirring.

-Preparation of membrane samples and laminates-
The prepared coating composition is coated (coating amount) on a template glass base material having a thickness of 3 mm (arithmetic mean roughness Ra of the coated surface = 0.4 μm) using a roll coater (material: EPDM (ethylene propylene diene rubber)). ^{:. 0.2mL / m 2 ~3mL /} m 2) , thereby forming a coating film was then formed by coating film, an oven and heated for 1 minute at ambient temperature 100 ° C. using a dried.
Next, the dried coating film was fired at an atmospheric temperature of 700 ° C. for 3 minutes using an electric furnace to prepare a film sample (antireflection film).
As described above, a laminate having a film sample as an antireflection film on a glass substrate was obtained. The film sample was formed so that the final average film thickness of the film sample formed on the glass substrate was 130 nm.
Ra was measured using a surface roughness meter (model number: Handy Surf E-35B, manufactured by Tokyo Seimitsu Co., Ltd.) in accordance with JIS-B0601.

For the average film thickness, a laminate having a film sample (antireflection film) after firing on a glass substrate is cut in parallel in a direction orthogonal to the substrate surface of the substrate, and the cut surface is cut by a scanning electron microscope (SEM). ), The film thickness of each observation point was measured from 10 SEM images, and the obtained 10 measurement values (film thickness) were averaged for confirmation.

-Evaluation-
The following evaluation was carried out using the coating composition, the film sample or the laminate obtained above. The evaluation results are shown in Table 1. In addition, in Table 1, the description of "-" in the addition amount of each component indicates that the corresponding component is not contained.

(1) Antireflection (AR) property A wavelength of 380 nm of a laminate in which a film sample (antireflection film) is formed on a glass substrate by an ultraviolet visible infrared spectrophotometer (model number: UV3100PC, manufactured by Shimadzu Corporation). The reflectance (%) in light of ~ 1,100 nm was measured using an integrating sphere. The reflectance was measured by attaching a black tape to the front surface of the glass substrate, which is the back surface, in order to suppress the reflection on the back surface of the laminate (the surface on the side where the film sample of the glass substrate is not formed). .. Then, the reflectance of each wavelength at the measured wavelength 380Nm～1,100nm, the average reflectance of the laminate; was calculated ^{(R AV} units%).
In the same manner as described above, the reflectance (%) of the glass substrate on which the film sample was not formed was measured in light having a wavelength of 380 nm to 1,100 nm. ^{Then, the average reflectance (R 0AV} ; unit%) of the glass substrate was calculated from the measured reflectance of each wavelength in the measured wavelengths of 380 nm to 1,100 nm.
The above average reflectance R ^AV, from R ^0AV, the average reflectivity change for the glass base material not film sample is formed ([Delta] R; unit:%) was calculated according to the following formula (a).
ΔR indicates that the larger the value, the better the antireflection (AR) property.
ΔR = R ^0AV −R ^AV equation (a)
The permissible range of antireflection is 2.1% or more, preferably 2.5% or more.

(2) Scratch resistance (pencil hardness)
UNI (registered trademark) manufactured by Mitsubishi Pencil Co., Ltd. was used as the pencil, and the pencil hardness of the film surface (antireflection layer surface) of the film sample was adjusted to the method described in JIS K-5600-5-4 (1999). Therefore, it was measured.
The permissible range of pencil hardness is B or more, and preferably H or more. In the present specification, for example, "pencil hardness is B or more" means that the pencil hardness is B or harder than that (for example, HB, F, H, etc.).
The measured pencil hardness was ranked according to the evaluation criteria shown below. Ranks 3 to 5 are the allowable range of pencil hardness. The results are shown in Tables 1 and 2.
<Evaluation criteria>
A: Pencil hardness is 6H or more.
B: The pencil hardness is 4H to 5H.
C: Pencil hardness is B to 3H.
D: Pencil hardness is 2B or less.

(3) Antifouling property (tape adhesive residue)
Cellotape (registered trademark) (manufactured by Nichiban Co., Ltd., width 18 mm, length 56 mm) was attached to the film surface of the film sample and rubbed with an eraser to attach the tape to the sample film. One minute after the tape was applied, the end of the tape was held at right angles to the sample film surface, and the tape was instantly peeled off.
After that, the area where the tape of the sample film was attached was divided into 100 continuous sections of 1.8 mm × 5.6 mm size in 10 rows × 10 columns = 100, and the tape was adhered out of the 100 sections. The number (x) of the compartments where the agent was peeled off from the tape and remained was measured. The smaller the value of x, the better the antifouling property (tape adhesive residue).
The permissible range of tape adhesive residue is that the number of compartments (x) is 9 or less. The number of measured sections (x) was ranked according to the evaluation criteria shown below. Rank A or B is an acceptable range.
<Evaluation criteria>
A: x ≤ 3 B: 4 ≤ x ≤ 9 C: 10 ≤ x ≤ 50 D: x> 50

(4) Liquid Time Stability The viscosity of the coating composition at 25 ° C. was measured using a vibration viscometer (manufactured by SEKONIC Corporation, model VISCOMATE VM-100A). The viscosity of the coating composition measured immediately after the preparation of the coating composition was set to η ⁰ day, the viscosity of the coating composition after being left at 40 ° C. for 10 days was set to η ¹⁰ day, and the viscosity change value η was calculated from the following formula (a). did.
η = η ¹⁰ day / η ⁰ day equation (a)
The closer the calculated value of η is to 1, the smaller the change in viscosity of the liquid with time, and the better the stability of the coating composition with time. The permissible range of viscosity change is 1.40 or less, preferably 1.20 or less, and more preferably 1.10 or less.
<Evaluation criteria>
A: 1 ≤ η <1.2
B: 1.2 ≤ η ≤ 1.5
C: η> 1.5

(Examples 2 to 10, Comparative Examples 1 to 5)
In Example 1, the coating composition was prepared and evaluated in the same manner as in Example 1 except that the components used in the coating composition were changed as shown in Table 1 below. The evaluation results are shown in Table 1.

(Examples 11 to 17)
In Example 1, the formula (1) with respect to the total mass of the hydrolyzable silane compound by containing two or more kinds of the hydrolyzable silane compound used in the coating composition and the partially hydrolyzed condensate of the hydrolyzable silane compound. ), The coating composition was prepared and evaluated in the same manner as in Example 1 except that the mass ratio of the content of the compound was changed. The evaluation results are shown in Table 2.
Further, in Example 15, the mass ratio of the content of the polymer particles to the sum of the content of the silica particles and the content of the silane compound in terms of silicon dioxide is 0.37.
In Table 2, the description of "-" in the addition amount of each component indicates that the corresponding component is not contained.

(Examples 18 to 26)
In Example 1, by changing the content of isopropanol and water used in the coating composition, the content of the organic solvent in which the ^{hydrogen bond term (δH) of the solubility parameter is 16 MPa 1/2 or more with respect to the total mass of the solvent can be adjusted.} A coating composition was prepared and evaluated in the same manner as in Example 1 except that it was changed. The evaluation results are shown in Table 3.
In Table 3, the description of "-" in the addition amount of each component indicates that the corresponding component is not contained.

Details of the components shown in Tables 1 to 3 are shown below.
Trimethoxysilane: (hydrogenated trifunctional silane compound), manufactured by Tokyo Kasei Kogyo Co., Ltd. Triethoxysilane: (hydrogenated trifunctional silane compound), manufactured by Tokyo Kasei Kogyo Co., Ltd. Hydrogen silsesquioxane oligomer: synthesized by the following method (Hydrogenated trifunctional silane compound)
Methyltrimethoxysilane: KBM-13 (trifunctional silane compound), manufactured by Shinetsu Chemical Industries, Ltd. Triethoxy (1H, 1H, 2H, 2H-nonafluorohexyl) silane: (trifunctional silane compound), manufactured by Tokyo Kasei Kogyo Co., Ltd. Phenyltrimethoxysilane: KBM-103 (trifunctional silane compound), manufactured by Shin-Etsu Chemical Industries, Ltd. Tetraethoxysilane: KBE-04 (trifunctional silane compound), manufactured by Shin-Etsu Chemical Industries, Ltd. Acetic acid: Acetic acid aqueous solution (pKa: 4. 76, 10 mass% acetic acid aqueous solution prepared by diluting Wako Pure Chemical Industries, Ltd. with deionized water Nitrate: Nitrate aqueous solution (d.1.38, pKa: -1.4, manufactured by Wako Pure Chemical Industries, Ltd.) ) Was diluted with deionized water to prepare a 40 mass% nitrate aqueous solution. Ammonium acetate: ammonium acetate (pKa: 4.8, manufactured by Wako Pure Chemical Industries, Ltd.) was diluted with deionized water to prepare 50 mass% acetate. Ammonium aqueous solution Snowtex (registered trademark) ST-OXS: Spherical silica particles (number average primary particle diameter: 4 nm to 6 nm, solid content: 10 mass% aqueous solution), manufactured by Nissan Chemical Industries, Ltd. Water: Deionized water 2-propanol : Tokuso IPA (boiling point = 82.2 ° C, δH = 16.2MPa ^1/2 ), manufactured by Tokuyama Co., Ltd. Ethanol: boiling point = 78.3 ° C, δH = 18.3MPa ^1/2 , manufactured by Wako Pure Chemical Industries, Ltd. Methanol: boiling point = 64.5 ° C, δH = 21.4 MPa ^1/2 , manufactured by Wako Pure Chemical Industries, Ltd. Ethanol glycol: boiling point = 197.3 ° C, δH = 27.7 MPa ^1/2 , Wako Pure Chemical Industries, Ltd. Hydroxyacelane: Boiling = 145 ° C, δH = 17.7MPa ^1/2 , Wako Pure Chemical Industries, Ltd. Butanol: Boiling = 99 ° C, δH = 14.7MPa ^1/2 , Wako Pure Chemical Industries, Ltd. Ethanol: Boiling point = 56 ° C., δH = 5.1 MPa ^1/2 , manufactured by Wako Pure Chemical Industries, Ltd.

The synthesis of the hydrogen silsesquioxane oligomer was carried out as follows. That is, 50.5 g of p-toluenesulfonic acid monohydrate, 151.5 g of 90% by mass sulfuric acid and 429.5 g of chlorobenzene were mixed in a flask, stirred and mixed at 250 rpm, and separated from the aqueous phase and the organic phase. A two-phase mixture was prepared. Further, 50.0 _{g of HSiCl 3} dissolved in 70.0 g of chlorobenzene was added over 50 minutes. After the addition, the reaction mixture was stirred for 2 hours. The mixture was then placed in a separatory funnel and the aqueous phase was drained. The obtained organic phase was washed twice with 100 mL of 47% sulfuric acid and further twice with 100 mL of deionized water. _{About 20 g of CaCO 3} was added to this organic phase, and the mixture was stirred for 10 minutes to neutralize, then about 20 g of sulfonyl ₄ was added, and the mixture was stirred for 10 minutes to dehydrate. The solution was filtered and then the solvent was stripped. 17.9 g of a soluble resin (hydrogen silsesquioxane resin) was obtained, and the yield was 91%.

In the coating compositions of Examples 1 to 26, each of the coating compositions has a plurality of isolated pores that are not connected to each other inside the film, and the film surface has open pores having a diameter of 5 nm or more. A non-porous porous membrane was obtained.
As shown in Table 1, in the coating compositions of Examples 1 to 10, good results were obtained in all of the antireflection property, the antifouling property and the scratch resistance as compared with the Comparative Example. In particular, delta] H of the organic solvent is ^{16 MPa 1/2} or more ^{22 MPa 1/2} or less is applied compositions of Examples 1-5 and 7-10, the organic solvent delta] H is larger in Example 6 than ^{22 MPa 1/2} Better antireflection properties were obtained as compared with the coating composition.

On the other hand, in Comparative Example 1 which does not contain a hydrogenated trifunctional silane compound and contains a tetrafunctional silane compound having an alkoxy group, the silane compound cannot be unevenly distributed on the film surface, and a dense silica matrix is not formed on the film surface. As a result, the antifouling property deteriorated and the scratch resistance was inferior.
Further, in Comparative Examples 2 and 3 containing no organic solvent having δH of 16 MPa ^{1/2 or more, the antireflection property was inferior.}

Further, as shown in Table 2, the coating compositions of Examples 11 to 17 in which the hydrogenated trifunctional silane compound and the trifunctional silane compound were combined were excellent in all of antireflection, antifouling property and scratch resistance. there were.
Among them, the coating compositions of Examples 11 to 15 in which the content of the hydrogenated trifunctional silane compound exceeds 50% by mass with respect to the total mass of the entire silane compound are described in Examples 16 and 17 in which the content is less than 50% by mass. In comparison, it can be seen that it is superior in scratch resistance.
Further, it can be seen that the coating composition of Example 11 containing two types of hydrogenated trifunctional silane compounds and having the above content of 100% by mass is more excellent in scratch resistance.

Table 3 shows the effect of the content of the organic solvent in which ^{δH is 16 MPa 1/2} or more on the total mass of the solvent.
Examples 19 and 20 in which the content is 50% by mass or more and less than 75% by mass are more excellent. Further, the coating compositions of Examples 18 and 22 to 26 having the above content of 75% by mass or more were remarkably excellent in antireflection.

The disclosure of Japanese Patent Application No. 2017-1972, filed September 29, 2017, is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards described herein are to the same extent as if the individual documents, patent applications, and technical standards were specifically and individually stated to be incorporated by reference. Incorporated herein by reference.

The coating composition of the present disclosure is suitable for a wide range of technical fields in which image defects typified by bright spot defects are suppressed and high quality in appearance is required. For example, an optical lens, an optical filter, a surveillance camera, and a label are suitable. Or, a protective film, an antireflection film, and a thin film transistor of various displays provided on a member on the light incident side (front glass, lens, etc.) of a solar cell module, etc. It is preferably used as a flattening film for (TFT).

Claims (10)

With polymer particles
A silane compound selected from a hydrolyzable silane compound represented by the following formula (1) and a partially hydrolyzed condensate of the hydrolyzable silane compound, and
An organic solvent having a solubility parameter hydrogen bond term of 16.2 MPa ^1/2 or more and 27.7 MPa ^1/2 or less,
Only including,
The content of the organic solvent with respect to the total mass of the solvent is 31.2% by mass or more and 100% by mass or less.
The content of the silane compound selected from the hydrolyzable silane compound represented by the formula (1) and the partially hydrolyzed condensate of the hydrolyzable silane compound is 50% by mass or more and 100% with respect to the total amount of the silane compound. A coating composition that is less than or equal to mass%.
H-Si (OR ¹ ) ₃ formula (1)
In formula (1), R ¹ independently represents an alkyl group having 1 to 3 carbon atoms. The coating composition according to claim 1, further comprising a hydrolyzable silane compound represented by the following formula (2) and a partially hydrolyzed condensate of the hydrolyzable silane compound.
R ^3- Si (OR ² ) ₃ formula (2)
In the formula (2), R ² independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ³ is an alkyl group having 1 to 8 carbon atoms and an alkyl fluoride having 1 to 8 carbon atoms. Represents a group or an aryl group having 6 to 12 carbon atoms. The coating composition according to claim 1 or 2, wherein the organic solvent has a boiling point of 50 ° C. or higher and lower than 200 ° C. The coating composition according to any one of claims 1 to 3 , wherein the coating composition contains water and the content of the organic solvent with respect to the total mass of the solvent is 50% by mass or more. The coating composition according to any one of claims 1 to 4 , wherein the solid content concentration is 1% by mass or more and 20% by mass or less with respect to the total mass of the coating composition. A laminate having a cured product of the coating composition according to any one of claims 1 to 5 on a base material. The laminate according to claim 6 , wherein the base material is a glass base material. The laminate according to claim 7 , wherein the glass base material has an uneven structure on the surface. A solar cell module comprising the laminate according to any one of claims 6 to 8. A step of applying the coating composition according to any one of claims 1 to 5 on a substrate with a roll coater to form a coating film.
The step of drying the coating film and
A method for producing a laminate, comprising a step of firing the coating film after drying.