JP2016087561A - Aqueous coating liquid, film, production method of the same, laminate and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous coating liquid forming a film having excellent antireflection property and scratch resistance, the film having excellent antireflection property and scratch resistance, a production method of the same, a laminate and a solar cell module.SOLUTION: A production method of a film including: a step forming a coating film by coating an aqueous coating liquid containing water, one kind of non-porous silica particles having an average primary particle diameter of 8 nm or less as silica particles and a surfactant and having a pH value of 1.5-3.5 on a base material; and a step drying the coating film coated and formed, and an application of the same are provided.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous coating solution, a film and a method for producing the same, a laminate, and a solar cell module.

The aqueous coating solution containing silica fine particles uses a solvent containing water, and is used for various applications because the formed film has low surface energy and excellent transparency.
As its application, it is suitably used for antireflection film, optical lens, optical filter, flat film for thin film transistor (TFT) of various displays, anti-condensation film, antifouling film, surface protective film and the like.

Among these, the antireflection film is useful because it can be used for, for example, a solar cell module, a monitoring camera, a lighting device, a protective film for a sign, and the like. Various coating compositions and coating methods have been developed for anti-reflective coating applications.
For example, as a coating method for imparting at least one property of antireflection and durability to a substrate, non-spherical nanoparticles, spherical nanoparticles, optionally a surfactant, and water, Applying a coating composition having at least a portion of the spherical nanoparticles having functional groups on the surface to the substrate, and drying the coating composition to form a hydrophilic coating on the substrate. A reforming method has been proposed (see, for example, Patent Document 1).

  In addition, as a coating composition that can be used for optical coating such as antireflection coating, nanoparticles containing a core material containing a cationic polymer and a shell material containing a metal oxide, and having an average specific size of 10 nm to 200 nm A composition containing the same has been proposed (see, for example, Patent Document 2).

  Further, as a coating material for forming a low reflection film, a coating material containing a metal oxide composed of silica fine particles having air layers and / or porous silica fine particles and a resin has been proposed (for example, Patent Document 3). reference).

Special table 2013-527879 gazette Japanese Patent No. 5266549 JP 2009-54352 A

However, although the base material surface modified by the method described in Patent Document 1 has excellent antireflection properties, sufficient scratch resistance has not been obtained.
Moreover, although the layer obtained by the composition or coating material of patent document 2 and patent document 3 is also excellent in anti-reflective property, scratch resistance was not enough.
That is, the actual situation is that a film having excellent antireflection properties and scratch resistance has not been provided.

  The present invention has been made in view of the above circumstances, an aqueous coating liquid on which a film excellent in antireflection and scratch resistance is formed, a film excellent in antireflection and scratch resistance, and the film It aims at providing a manufacturing method, a laminated body, and a solar cell module, and makes it a subject to achieve this objective.

Specific means for achieving the object are as follows.
<1> On the substrate, water, one kind of nonporous silica particles having an average primary particle diameter of 8 nm or less as silica particles, and a surfactant, and having a pH of 1.5 to 3.5 A method for producing a film, comprising: a step of applying a certain aqueous coating solution to form a coating film; and a step of drying the coating film formed by coating.

<2> The method for producing a film according to <1>, wherein the non-porous silica particles have an average primary particle diameter of 6 nm or less.
<3> The method for producing a film according to <1> or <2>, wherein the pH of the aqueous coating solution is 1.8 to 3.0.
<4> The film according to any one of <1> to <3>, further including a step of baking the coated film after drying at a temperature of 400 ° C. or higher and 800 ° C. or lower after the step of drying the coated film. Manufacturing method.
<5> The method for producing a film according to <4>, wherein the baking is performed at a temperature of 500 ° C. or higher and 800 ° C. or lower.
<6> The method for producing a film according to <4> or <5>, wherein the step of baking forms a particle connected body in which a plurality of nonporous silica particles are connected by baking.
<7> The method for producing a film according to any one of <4> to <6>, wherein the coating film after baking has a thickness of 50 nm to 350 nm.
<8> At least the coating film after drying has an absolute value of an average reflectance change ΔR at 2.0 ° of light having a wavelength of 400 nm to 1100 nm defined by the following formula (1) of 2.0% or more. <1>-<7> The manufacturing method of the film | membrane as described in any one.

| Average reflectance change ΔR | = | _{Average reflectance after} R _{film formation−Average reflectance of} R _{base material} | Formula (1)

<9> The method for producing a film according to <8>, wherein the absolute value of the average reflectance change ΔR is 2.5% or more.

<10> An aqueous coating solution having a pH of 1.5 to 3.5, comprising water, one kind of nonporous silica particles having an average primary particle diameter of 8 nm or less as silica particles, and a surfactant.
<11> The aqueous coating solution according to <10>, wherein the average primary particle diameter of the nonporous silica particles is 6 nm or less.
<12> The aqueous coating solution according to <10> or <11>, wherein the pH of the aqueous coating solution is 1.8 to 3.0.
<13> The aqueous coating liquid according to any one of <10> to <12>, wherein the surfactant is a nonionic surfactant.

<14> A film containing one kind of nonporous silica particles having an average primary particle diameter of 8 nm or less as silica particles and a film thickness of 50 nm to 350 nm.
<15> The membrane according to <14>, wherein the non-porous silica particles have an average primary particle size of 6 nm or less.
<16><14> or <15> defined by the following formula (1), wherein the absolute value of the average reflectance change ΔR at the time of 5 ° incidence with light having a wavelength of 400 nm to 1100 nm is 2.0% or more The membrane described.

| Average reflectance change ΔR | = | _{Average reflectance of base material after} R _{film formation−Average reflectance of} R _{base material} | Formula (1)

<17> The film according to <16>, wherein the absolute value of the average reflectance change ΔR is 2.5% or more.

<18> The membrane according to any one of <14> to <17>, wherein the nonporous silica particles are contained as a state of a particle connected body in which a plurality of nonporous silica particles are connected.
<19> The film according to any one of <14> to <17>, further containing a surfactant.
<20> The film according to any one of <14> to <19>, wherein the surface roughness Ra is 20 nm or less.

<21> On the base material, the film produced by the production method according to any one of <1> to <9> or the film according to any one of <14> to <20> is provided. Laminated body.
<22> The laminate according to <21>, wherein the substrate is a glass substrate.

<23> A solar cell module including the laminate according to <21> or <22>.

  ADVANTAGE OF THE INVENTION According to this invention, the aqueous coating liquid in which the film | membrane excellent in antireflection and scratch resistance is formed, the film | membrane excellent in antireflection and scratch resistance, its manufacturing method, a laminated body, and a solar cell module are provided. Provided.

<Method for producing membrane>
The film production method of the present invention comprises, on a substrate, water, one kind of nonporous silica particles having an average primary particle diameter of 8 nm or less as silica particles, and a surfactant, and has a pH of 1. A step of applying an aqueous coating solution of 5 to 3.5 to form a coating film, and a step of drying the coating film formed by coating.
The method for producing a film of the present invention preferably includes a step of baking the dried coating film at a temperature of 400 ° C. or higher and 800 ° C. or lower after the step of drying the coated film.

Although the operation of the present invention is not clear, it is estimated as follows.
The film production method of the present invention includes one kind of nonporous silica particles having an average primary particle size of 8 nm or less as silica particles in an aqueous coating liquid, and controls the pH of the aqueous coating liquid, thereby producing nonporous silica particles. The non-porous silica particles are softly agglomerated by making the surface zeta potential value zero or close to zero (the pH of the aqueous coating solution is close to pH 2.0, which is the isoelectric point of the silica particles). It is considered that a high void amount can be realized to form a state, and a film having excellent antireflection properties can be formed without using beaded (chain) silica particles.
And since the average primary particle diameter of a nonporous silica particle is 8 nm or less, it is thought that the film | membrane formed is dense and it is excellent in the flaw resistance of a film | membrane.
When these are combined, a film excellent in antireflection and scratch resistance that cannot be achieved with an aqueous coating agent containing silica linked in a chain, porous silica, hollow silica, or the like is formed. Conceivable.
Furthermore, since the average primary particle diameter of the nonporous silica particles is 8 nm or less, the surface of the formed film is smooth and the adhesion of dirt to the film is suppressed. Therefore, the film produced by the production method of the present invention is excellent in antifouling properties in addition to the antireflection properties and scratch resistance.

  Hereafter, each process in the manufacturing method of the film | membrane of this invention is demonstrated in detail.

[Process for forming coating film]
The film production method of the present invention comprises, on a substrate, water, one kind of nonporous silica particles having an average primary particle diameter of 8 nm or less as silica particles, and a surfactant, and has a pH of 1. A step of applying an aqueous coating solution of 5 to 3.5 to form a coating film.

(Aqueous coating solution)
The aqueous coating liquid in the present invention contains water, one kind of nonporous silica particles having an average primary particle diameter of 8 nm or less as silica particles, and a surfactant, and has a pH of 1.5 to 3.5. is there.
In the aqueous coating solution of the present invention, it is particularly important in terms of antireflection properties that the silica particles contain only one kind of nonporous silica particles having an average primary particle diameter of 8 nm or less. That is, by using nonporous silica particles having a specific average primary particle diameter without using these silica particles, a membrane that has conventionally used bead-like (chain-like) silica particles or porous silica particles is used. By forming it, it is possible to impart antireflection properties while maintaining good scratch resistance, which is rather unsatisfactory with beaded silica particles. And the improvement effect of antireflection property is heightened in combination with the pH of the aqueous coating solution being 1.5 to 3.5.
Moreover, since very fine silica particles having an average primary particle size of 8 nm or less are used, the formed coating film is dense, has a smooth surface, and is excellent in scratch resistance and antifouling properties.
From the above viewpoint, the aqueous coating liquid in the present invention preferably has an average primary particle diameter of nonporous silica particles of 6 nm or less and a pH of 1.8 to 3.0.

-Nonporous silica particles-
The aqueous coating liquid in the present invention contains one kind of nonporous silica particles having an average primary particle diameter of 8 nm or less as silica particles.
“Non-porous silica particles” means particles having no voids inside silica particles, and are distinguished from hollow silica particles, porous silica particles, and the like particles having voids inside. . In addition, the “nonporous silica particles” have a core such as a polymer inside the particles, and the outer shell (shell) of the core is silica or a precursor of silica (for example, a material that changes to silica by firing). The core-shell structured silica particles are not included.

The average primary particle diameter of the nonporous silica particles in the present invention is 8 nm or less. When the average primary particle diameter exceeds 8 nm, the antireflection property is poor.
The average primary particle size is preferably 6 nm or less, more preferably 2 nm to 4 nm from the above viewpoint.

  The average primary particle diameter of the nonporous silica particles can be determined from the photograph obtained by observing the dispersed particles with a transmission electron microscope. From the image of the photograph, the projected area of the particle is obtained, and the equivalent circle diameter is obtained therefrom, and the average particle size (average primary particle size) is obtained. The average primary particle diameter in this specification is a value obtained by measuring the projected area of 300 or more particles, obtaining the equivalent circle diameter, and arithmetically averaging the values.

  Commercially available nonporous silica particles may be used, and examples thereof include NALCO (registered trademark) 8699, 2326, and 1115 manufactured by NALCO.

The content of the nonporous silica particles in the aqueous coating solution is preferably 5% by mass to 99% by mass and more preferably 10% by mass to 98% by mass with respect to the total solid content of the aqueous coating solution. Preferably, it is 15 mass%-97 mass%.
When the content of the nonporous silica particles is in the above range, the aqueous coating liquid in the present invention has excellent antireflection properties, scratch resistance, and antifouling properties, and can form a hydrophilic film. Become.

-Water-
The aqueous coating solution in the present invention contains water.
By using water as the aqueous medium of the aqueous coating solution, the burden on the environment is greatly reduced as compared with a coating solution using a large amount of a volatile organic solvent.
The aqueous coating solution of the present invention may further contain a hydrophilic organic solvent having excellent affinity with water.
When the aqueous coating solution contains a hydrophilic organic solvent, the surface tension of the aqueous coating solution becomes lower and more uniform coating is possible. Further, when the hydrophilic organic solvent is a low-boiling organic solvent, the ratio of the low-boiling organic solvent in the aqueous medium increases, and therefore there are advantages such as easy drying of the aqueous coating solution.

  The hydrophilic organic solvent is not particularly limited, and examples thereof include methanol, ethanol, isopropanol, butanol, acetone, ethylene glycol, and ethyl cellosolve. Alcohol is preferable from the viewpoint of availability and reduction of environmental burden, and ethanol, isopropanol, and the like are more preferable.

  When the aqueous coating solution contains a hydrophilic organic solvent in addition to water as an aqueous medium, the content of water used in the aqueous coating solution is preferably 30% by mass or more based on the total mass of the aqueous medium. More preferably, it is at least mass%.

  The solid content with respect to the total mass of the aqueous coating liquid in the present invention is preferably in the range of 0.1% by mass to 30% by mass, more preferably in the range of 0.2% by mass to 20% by mass. More preferably, it is in the range of 5% by mass to 10% by mass. The solid content of the aqueous coating solution can be adjusted by adjusting the content of the solvent, particularly water.

-Surfactant-
The aqueous coating liquid in the present invention contains at least one surfactant.
When the aqueous coating solution contains a surfactant, the coating property of the aqueous coating solution is improved, and the surface tension of the aqueous coating solution is lowered. Therefore, the uniform coating property and coating surface property of the formed film are excellent.

Examples of the surfactant include nonionic surfactants, anionic surfactants that are ionic surfactants, cationic surfactants, and amphoteric surfactants, all of which are preferably used in the present invention. be able to.
If the ionic surfactant is used in excess, it is difficult to adjust the pH of the aqueous coating solution within a predetermined range. Therefore, it is preferable to use a nonionic surfactant as the surfactant in terms of a high degree of freedom in the content of the surfactant.

  Examples of the nonionic surfactant include polyalkylene glycol monoalkyl ether, polyalkylene glycol monoalkyl ester, polyalkylene glycol monoalkyl ester / monoalkyl ether, and the like. More specific examples of the nonionic surfactant include polyethylene glycol monolauryl ether, polyethylene glycol monostearyl ether, polyethylene glycol monocetyl ether, polyethylene glycol monolauryl ester, polyethylene glycol monostearyl ester, and the like.

  A nonionic surfactant is not specifically limited, A commercially available thing may be used, for example, TRITON BG10 by Dow Chemical Co., etc. are mentioned.

On the other hand, it is preferable in that the aqueous coating liquid contains an ionic surfactant to improve hydrophilicity.
If the ionic surfactant is contained excessively, silica particles are likely to aggregate, and therefore, generally there are few examples of using an ionic surfactant and silica particles in combination. However, when an ionic surfactant is added to the aqueous coating solution, the antifouling property of the coating film formed by the aqueous coating solution is increased by using it in a content that is less than the amount that causes aggregation of the silica particles. Can do.

  Examples of ionic surfactants include anionic surfactants such as alkyl sulfates, alkylbenzene sulfonates and alkyl phosphates, cationic surfactants such as alkyltrimethylammonium salts and dialkyldimethylammonium salts, alkylcarboxyl Examples include amphoteric surfactants such as betaine.

The content of the surfactant in the aqueous coating solution in the present invention is preferably 0.01% by mass or more, and 0.02% by mass or more with respect to the total mass of the aqueous coating solution, from the viewpoint of antifouling properties of the coating film. It is more preferable that it is 0.03 mass% or more.
By setting the content of the surfactant in the above range, the wettability can be improved, and the coating property of the aqueous coating liquid is improved.

The upper limit of the content of the surfactant is not particularly limited, but depending on the type of surfactant, there is a concern that it may segregate on the surface after application of the aqueous coating liquid and the strength of the coating film may be reduced. Therefore, considering the content of other components, the content of the surfactant is preferably 10% by mass or less, more preferably 8% by mass or less, based on the total mass of the aqueous coating solution. More preferably, it is 5 mass% or less.
Further, when an ionic surfactant is used as the surfactant, the ionic surfactant is used from the viewpoint of further improving the antifouling property and suppressing aggregation of nonporous silica particles due to the influence of the surfactant. The content of is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and 1.0% by mass or less with respect to the total mass of the aqueous coating solution. Further preferred.

-PH of aqueous coating solution-
The pH of the aqueous coating solution in the present invention is 1.5 to 3.5.
When the pH of the aqueous coating solution is less than 1.5, the antireflection property is poor, and when the pH exceeds 3.5, the antireflection property is inferior.
The reason is presumed as follows. That is, when the pH of the aqueous coating solution is in the above range, the non-porous silica particles are soft in the solution because the average primary particle diameter is close to the isoelectric point (pH 2.0) of the non-porous silica particles having a diameter of 8 nm or less. By agglomerating, being coated on the substrate in that state, and drying, the nonporous silica particles are densely arranged to form a film having voids between the particles. Thus, the film is considered to have excellent antireflection properties, scratch resistance, and antifouling properties.

  The pH of the aqueous coating solution is preferably 1.8 to 3.0 from the above viewpoint. The isoelectric point of the nonporous silica particles shows a slight up and down depending on the production method, primary particle diameter, and surface state. In that case, the pH of the aqueous coating solution is adjusted according to the pH of the isoelectric point. May be.

  The pH of the aqueous coating solution is a value measured at 25 ° C. using a pH meter (manufactured by Toa DKK Co., Ltd., HM-31P).

(Base material)
There is no restriction | limiting in particular in the base material which apply | coats an aqueous coating liquid, As a base material, all various base materials, such as glass, resin, a metal, and ceramics, can be used conveniently.
When glass is used as the base material, condensation of hydroxyl groups on silicon also occurs between the hydroxyl groups on the glass surface, thereby forming a coating film having excellent adhesion to the base material.

  The method for applying the aqueous coating solution to the substrate in the present invention is not particularly limited, and any known coating method such as spray coating, brush coating, roller coating, bar coating, dip coating, etc. can be applied. .

[Drying process]
The manufacturing method of the film | membrane of this invention includes the process of drying the coating film formed by application | coating.
By drying the coating film, a film containing nonporous silica particles and a surfactant is formed on the substrate.

The coating film may be dried at room temperature (25 ° C.) or using a heating device. The heating device can be used without particular limitation as long as it can be heated to a target temperature, and examples thereof include an oven, an electric furnace, or a firing device uniquely produced in accordance with a production line. The coating film may be dried by heating the coating film to 40 ° C. to 400 ° C. using these heating devices. When heating is performed, the heating time can be set to about 1 to 30 minutes.
The drying conditions in the step of drying the coating film are preferably 40 ° C to 200 ° C for 1 minute to 10 minutes, more preferably 100 ° C to 180 ° C for 1 minute to 5 minutes.

The coating film after drying in the present invention preferably has a film thickness of 50 nm or more. When the film thickness is 50 nm or more, the coating film after drying is excellent in antireflection properties.
From the above viewpoint, the film thickness is preferably from 50 nm to 350 nm, more preferably from 100 nm to 300 nm, and even more preferably from 100 nm to 250 nm.

[Step of firing]
The method for producing a film of the present invention preferably includes a step of baking the dried coating film at a temperature of 400 ° C. or higher and 800 ° C. or lower after the step of drying the coated film.

The state of the existing nonporous silica particles changes before and after the firing step. Specifically, in the coating film before firing, each nonporous silica particle is a single particle (aggregated state by van der Waals force, etc.) In the coating film after firing, at least a part of the plurality of nonporous silica particles is present as a particle connected body in which the nonporous silica particles are connected to each other.
In this case, the average primary particle diameter of the particles connected by firing is the diameter when only one of the connected particles is assumed to be a sphere without considering the connecting portion (for example, the neck portion). In addition, the average primary particle diameter of the particle | grains connected by baking can be calculated by the method similar to the average primary particle diameter of non-porous silica particle as stated above.

  In the calcination step, it is preferable that a plurality of nonporous silica particles are connected to form a particle connected body by calcination. Thereby, since the bonding force between the nonporous silica particles is improved, the scratch resistance of the film is further improved. In this regard, the same effect cannot be obtained in the case of using an aqueous coating solution using silica particles previously linked in a “beaded” manner.

  As for the firing conditions in the firing step, the firing temperature 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, and more preferably 1 minute to 5 minutes.

  Firing in the firing step can be performed using a heating device. The heating device can be used without any particular limitation as long as it can be heated to a target temperature, and examples thereof include an electric furnace or a firing device uniquely produced in accordance with a production line.

The coating film after firing in the present invention preferably has a thickness of 50 nm or more. When the film thickness is 50 nm or more, the coating film after baking has excellent antireflection properties.
From the above viewpoint, the film thickness is preferably from 50 nm to 350 nm, more preferably from 100 nm to 300 nm, and even more preferably from 100 nm to 250 nm.

The film produced by the production method of the present invention is excellent in antireflection properties, scratch resistance, and antifouling properties.
The preferred physical properties of the film of the present invention are shown below.

(Absolute value of average reflectance change ΔR)
The antireflection property of at least the coating film after drying in the present invention is expressed by the absolute value of the average reflectance change ΔR at 5 ° incidence in the light having a wavelength of 400 nm to 1100 nm, which is defined by the following formula (1). be able to.
Note that “at least the coating film after drying” may be a coating film that has undergone the above-described drying process, and includes a coating film that has undergone the above-described baking process after the drying process.

| Average reflectance change ΔR | = | _{Average reflectance of base material after} R _{film formation−Average reflectance of} R _{base material} | Formula (1)

The average reflectance change ΔR in the formula (1) is the average reflectance of the base material on which the coating film is not formed (the average reflectance of the R _{base material} ) and the average reflection of the base material having the coating film formed with the aqueous coating liquid The ratio ( _{average reflectance of the base material after the} R _{film is formed} ) can be obtained by measuring the barium sulfate white plate as a reference.

The reflectance can be measured by using a spectrophotometer with an integrating sphere. Specifically, it can be measured by, for example, an ultraviolet-visible infrared spectrophotometer (manufactured by JASCO Corporation, V-670). In the present invention, light having a wavelength of 400 nm to 1100 nm is used, and a value obtained by arithmetically averaging the reflectance values at the respective wavelengths measured using V-670 is adopted as the average reflectance.
The higher the absolute value of the average reflectance change ΔR of the film, the better the antireflection property.

  In the present invention, the absolute value of the average reflectance change ΔR of the coating film is preferably 2.0% or more, and more preferably 2.5% or more from the viewpoint of antireflection properties.

(Surface roughness Ra)
The surface roughness Ra can be measured in accordance with JIS B0601: 2001 using an atomic force microscope (AFM) (manufactured by Seiko Instruments Inc., SPA-400) (measurement range: 3 μm square).
The surface roughness Ra in the present invention is preferably 20 nm or less, and more preferably 10 nm or less.

(Water contact angle)
The water contact angle of at least the coating film after drying in the present invention is preferably 40 ° or less, more preferably 30 ° or less, further preferably 25 ° or less, and particularly preferably 15 ° or less. .
The water contact angle can be obtained as an average value obtained by measuring the contact angle with respect to pure water five times using a Drop Master 300 manufactured by Kyowa Interface Chemical Co., Ltd.
By making the water contact angle of a coating film into the said range, since sufficient hydrophilicity can be provided to a coating film, it is excellent in the antifouling property of a coating film.

<Aqueous coating solution>
The aqueous coating liquid of the present invention contains water, one kind of nonporous silica particles having an average primary particle diameter of 8 nm or less as silica particles, and a surfactant, and has a pH of 1.5 to 3.5. is there.
The aqueous coating solution is synonymous with the aqueous coating solution in the production method described above. By using the aqueous coating liquid of the present invention, a film excellent in antireflection property, scratch resistance and antifouling property can be produced.

In the aqueous coating solution of the present invention, the average primary particle diameter of the nonporous silica particles is preferably 6 nm, and the pH is preferably 1.8 to 3.0.
In the aqueous coating solution of the present invention, the surfactant is preferably a nonionic surfactant from the viewpoint of adjusting pH.

<Membrane>
The film of the present invention contains one kind of nonporous silica particles having an average primary particle diameter of 8 nm or less as silica particles, and the film thickness is 50 nm or more and 350 nm or less.
The nonporous silica particles in the membrane of the present invention have the same meaning as the nonporous silica particles in the production method of the present invention described above. The film of the present invention is excellent in antireflection properties, scratch resistance, and antifouling properties.

  When the average primary particle diameter of nonporous silica particles exceeds 8 nm, the film of the present invention is inferior in antireflection properties. The film thickness is preferably 100 nm to 300 nm, and more preferably 100 nm to 250 nm.

The non-porous silica particles in the film of the present invention preferably have an average primary particle diameter of 6 nm or less from the viewpoint of antireflection properties. The average primary particle diameter is more preferably 2 nm to 4 nm.
In the film of the present invention, the absolute value of the average reflectance change ΔR at 5 ° incidence in light having a wavelength of 400 nm to 1100 nm defined by the following formula (1) is preferably 2.0% or more. More preferably, it is 5% or more.

| Average reflectance change ΔR | = | _{Average reflectance of base material after} R _{film formation−Average reflectance of} R _{base material} | Formula (1)

The film of the present invention may be either of the following two aspects, and the first aspect is preferable from the viewpoint of scratch resistance of the film.
As a 1st aspect, the nonporous silica particle in the membrane | film | coat of the above-mentioned this invention is an aspect contained as a state of the particle | grain coupling body which the some nonporous silica particle connected.
When the nonporous silica particles contained in the film are a particle-linked body of a plurality of nonporous silica particles, the scratch resistance of the film is further improved while maintaining good antireflection properties.

  As a second aspect, the above-described film of the present invention further contains a surfactant. That is, the coating film is formed using the aqueous coating liquid of the present invention containing a surfactant, the coating film is dried, and the film is manufactured without the above-described baking process.

<Laminate>
The laminate of the present invention has a film produced by the production method of the present invention described above or the film of the present invention described above on a substrate.
Therefore, the laminate of the present invention is excellent in antireflection properties, scratch resistance, and antifouling properties.
The substrate in the laminate of the present invention is preferably a glass substrate from the viewpoint of adhesion.

  Since the laminate having the film of the present invention formed on a glass substrate is excellent in antireflection, scratch resistance, and antifouling properties, for example, a solar cell module, a monitoring camera, a lighting device, a protective film for a sign, etc. It can use suitably for the use of.

<Solar cell module>
The solar cell module of this invention is equipped with the laminated body which has the film | membrane manufactured by the manufacturing method of the above-mentioned this invention, or the film | membrane of the above-mentioned this invention.
The solar cell module of the present invention is typified by the laminate and polyester film of the present invention, which are provided with solar cell elements that convert sunlight light energy into electrical energy and that have excellent antireflection properties provided on the side on which sunlight enters. It is arranged between the solar cell backsheet. Between a laminated body and a polyester film, it can seal and comprise with sealing materials represented by resin, such as ethylene-vinyl acetate copolymer, for example.

  About members other than a laminated body and a back sheet, such as a solar battery module and a solar battery cell, for example, it describes in detail in "Solar power generation system constituent material" (Eiichi Sugimoto supervision, Kogyo Kenkyukai, 2008 issue) Has been. In the solar cell module of this invention, it is preferable to provide the laminated body of this invention in the sunlight incident side, and any structure may be taken.

  Examples of the base material provided on the side on which sunlight is incident include a glass base material, a transparent resin such as an acrylic resin, and the like. In the solar cell module of the present invention, the surface of the glass base material is reflected. In addition to prevention, a laminate having a film excellent in scratch resistance and antifouling properties is used.

The solar cell element used in the solar cell module of the present invention is not particularly limited, and silicon-based materials such as single crystal silicon, polycrystalline silicon, and amorphous silicon, copper-indium-gallium-selenium, copper-indium-selenium, Various known solar cell elements such as III-V and II-VI compound semiconductor systems such as cadmium-tellurium and gallium-arsenic can be applied.
Since the solar cell module of the present invention includes a laminate having a film with good antireflection, scratch resistance and antifouling properties on a glass substrate, the film on the surface is damaged even when used for a long time. In addition, the decrease in light transmission due to the contamination or the adhering contaminants is suppressed, and the adhering contaminants are easily removed with water such as rain, so that good power generation efficiency is maintained over a long period of time. The

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Example 1
[Preparation of Silica Dispersion 1A]
To 6.00 g of deionized water, 7.02 g of an aqueous dispersion of silica particles NALCO (registered trademark) 8699 (manufactured by NALCO, solid content 15 mass%, nonporous silica particles, average primary particle size = 3 nm) is added. Phosphoric acid was added dropwise to the solution obtained by stirring, and the pH was adjusted to 1.5 to 2.0 to prepare silica dispersion 1A.
The average primary particle size is determined by observing the particles with a transmission electron microscope, obtaining the projected area of 300 particles from the obtained photographic image, obtaining the equivalent circle diameter from each, and calculating the value thereof. The average value was defined as the average primary particle size.

[Preparation of aqueous coating solution 1]
To the silica dispersion 1A, add 23.5 g of deionized water, 1.06 g of ethanol, and 0.56 g of a 10 mass% aqueous solution of TRITON BG10 (manufactured by Dow Chemical Co., Ltd., nonionic surfactant), and add phosphoric acid. The pH of the solution was adjusted to 2.4 using it, and aqueous coating liquid 1 (solid content 2.76 mass%) was prepared.
The pH is a value measured at 25 ° C. using a pH meter (manufactured by Toa DKK Co., Ltd., HM-31P).

[Production of membrane sample]
The obtained aqueous coating solution 1 was coated on a glass substrate using a bar coater to form a coating film. This coating film was dried in an oven at 150 ° C. for 1 minute. Then, it baked on 750 degreeC and the conditions for 3 minutes with the electric furnace, and produced the film | membrane sample. The final film thickness of the coating film on the glass substrate was set to 190 nm. Moreover, when the surface roughness Ra of the film sample was measured by the method described above, the surface roughness Ra was 10 nm or less.

(Example 2)
[Preparation of silica dispersion 1B]
The silica aqueous dispersion NALCO (registered trademark) 8699 used in Example 1 was changed to NALCO (registered trademark) 2326 (manufactured by NALCO, solid content 15% by mass, nonporous silica particles, average primary particle size = 5 nm). Except for the change, a silica dispersion 1B was prepared in the same manner as in Example 1.

[Preparation of aqueous coating solution 2]
An aqueous coating solution 2 was prepared in the same manner as in Example 1, except that the silica dispersion 1A used in Example 1 was changed to the silica dispersion 1B and the pH was adjusted to 2.1 with phosphoric acid.

[Production of membrane sample]
A film sample was prepared in the same manner as in Example 1 except that the aqueous coating solution 1 used in Example 1 was changed to the aqueous coating solution 2. Moreover, when the surface roughness Ra of the film sample was measured by the method described above, the surface roughness Ra was 20 nm or less.

(Comparative Example 1)
[Preparation of silica dispersion 1C]
The silica aqueous dispersion NALCO (registered trademark) 8699 used in Example 1 was changed to NALCO (registered trademark) 1030 (manufactured by NALCO, solid content 15% by mass, nonporous silica particles, average primary particle size = 13 nm). A silica dispersion 1C was prepared in the same manner as Example 1 except for the change.

[Preparation of aqueous coating solution 3]
An aqueous coating solution 3 was prepared in the same manner as in Example 1 except that the silica dispersion 1A used in Example 1 was changed to the silica dispersion 1C and the pH was adjusted to 2.3 with phosphoric acid.

[Production of membrane sample]
A film sample was prepared in the same manner as in Example 1 except that the aqueous coating solution 1 used in Example 1 was changed to the aqueous coating solution 3.

(Comparative Example 2)
[Preparation of silica dispersion 1D and aqueous coating solution 4]
Except for adjusting the silica dispersion 1A in Example 1 except that the pH was adjusted to 1.3, a silica dispersion 1D was prepared in the same manner as in Example 1, and the silica dispersion 1A was changed to the silica dispersion 1D. Prepared an aqueous coating solution 4 in the same manner as in Example 1.

[Production of membrane sample]
A film sample was prepared in the same manner as in Example 1 except that the aqueous coating solution 1 used in Example 1 was changed to the aqueous coating solution 4.

(Comparative Example 3)
[Preparation of silica dispersion 1E and aqueous coating solution 5]
In the preparation of the silica dispersion 1A in Example 1, the silica dispersion 1E was prepared in the same manner as in Example 1 except that the pH was adjusted to 3.9, and the silica dispersion 1A was changed to the silica dispersion 1E. An aqueous coating solution 5 was prepared except that the procedure was the same as in Example 1.

[Production of membrane sample]
A film sample was prepared in the same manner as in Example 1 except that the aqueous coating solution 1 used in Example 1 was changed to the aqueous coating solution 5.

(Example 3)
[Production of membrane sample]
A film sample was produced in the same manner as in Example 1 except that the firing conditions in Example 1 were changed to 600 ° C. for 3 minutes. Moreover, when the surface roughness Ra of the film sample was measured by the method described above, the surface roughness Ra was 20 nm or less.

Example 4
[Production of membrane sample]
A film sample was produced in the same manner as in Example 1 except that the firing conditions in Example 1 were changed to 500 ° C. for 3 minutes. Moreover, when the surface roughness Ra of the film sample was measured by the method described above, the surface roughness Ra was 20 nm or less.

(Example 5)
[Production of membrane sample]
A film sample was produced in the same manner as in Example 1 except that the firing conditions in Example 1 were changed to 450 ° C. for 3 minutes. Moreover, when the surface roughness Ra of the film sample was measured by the method described above, the surface roughness Ra was 20 nm or less.

(Example 6)
[Production of membrane sample]
A film sample was produced in the same manner as in Example 1 except that the firing conditions in Example 1 were changed to 350 ° C. for 3 minutes. Moreover, when the surface roughness Ra of the film sample was measured by the method described above, the surface roughness Ra was 20 nm or less.

(Comparative Example 4)
[Preparation of aqueous coating solution 6]
An aqueous coating solution 6 was prepared in the same manner as in Example 1 except that the TRITON BG10 used in the aqueous coating solution 1 of Example 1 was not added and the pH was adjusted to 2.3.

[Production of membrane sample]
A membrane sample was prepared in the same manner as in Example 1 except that the aqueous coating solution 1 used in Example 1 was changed to the aqueous coating solution 6. The final film thickness of the film sample was 190 nm.

(Comparative Example 5)
[Preparation of silica dispersion 2A (dispersion containing two types of silica)]
To 8.90 g of deionized water, 2.91 g of an aqueous dispersion NALCO (registered trademark) 8699 of silica (manufactured by NALCO, solid content 15% by mass, nonporous silica particles, average primary particle size = 3 nm) was added. Phosphoric acid was added dropwise to the solution obtained by stirring, and the pH was adjusted to 1.5 to 2.0 to prepare a first dispersion.
Next, 3.2 g of SNOWEX (registered trademark) -UP (Nissan Chemical Industries, Ltd., solid content 20 mass%, beaded (chain) silica particles) is added to 9.5 g of deionized water and stirred. 0.1 × 10 ³ mol / L sodium hydroxide was added dropwise to the resulting mixture to adjust the pH to about 12. Thereafter, 0.01 g of aminoethylaminopropyltrimethoxysilane (Z-6020, manufactured by Toray Dow Corning Co., Ltd.) in 0.8 g of ethanol was added dropwise, and this was mixed with a mixture adjusted to a pH of about 12 for 14 hours. Stir to prepare a second dispersion.
The first dispersion and the second dispersion were mixed to obtain a silica dispersion 2A.

[Preparation of aqueous coating solution 7]
To silica dispersion 2A, 12 g of deionized water, 0.26 g of ethanol, and 0.56 g of a 10 mass% aqueous solution of TRITON BG10 were added to prepare aqueous coating liquid 7 (solid content 2.82 mass%). The pH of the aqueous coating solution 7 was 2.6.

[Production of membrane sample]
A film sample was prepared in the same manner as in Example 1 except that the aqueous coating solution 1 used in Example 1 was changed to the aqueous coating solution 7. The final film thickness of the film sample was set to 170 nm.

(Comparative Example 6)
[Preparation of silica dispersion 2B (dispersion containing two types of silica)]
To 3.5 g of deionized water, 0.71 g of silica dispersion NALCO (registered trademark) 8699 (manufactured by NALCO, solid content 15% by mass, nonporous silica particles, average primary particle size = 3 nm) was added and stirred. Then, phosphoric acid was added dropwise to the resulting solution to adjust the pH to 1.5 to 2.0 to prepare a first dispersion.
Next, 5.0 g of SNOWTEX (registered trademark) -UP (Nissan Chemical Industry Co., Ltd., solid content 20 mass%, beaded (chain) silica particles) is added to 15.1 g of deionized water and stirred. 0.1 × 10 ³ mol / L sodium hydroxide was added dropwise to the resulting mixture to adjust the pH to about 12. Thereafter, 0.0015 g of aminoethylaminopropyltrimethoxysilane (manufactured by Toray Dow Corning Co., Ltd., Z-6020) in 1.3 g of ethanol was added dropwise, and this was mixed with a mixture adjusted to a pH of about 12 for 14 hours. Stir to prepare a second dispersion.
The first dispersion and the second dispersion were mixed to obtain silica dispersion 2B.

[Preparation of aqueous coating solution 8]
Aqueous coating solution 8 (solid content 2.90% by mass) was prepared by adding 12 g of deionized water and 0.56 g of a 10% by mass aqueous solution of TRITON BG10 to silica dispersion 2B. The pH of the aqueous coating solution 8 was 8.8.

[Production of membrane sample]
A film sample was prepared in the same manner as in Example 1 except that the aqueous coating solution 1 used in Example 1 was changed to the aqueous coating solution 8. The final film thickness of the film sample was 180 nm.

(Comparative Example 7)
[Preparation of Silica Dispersion 2C (Dispersion containing one kind of silica, beaded silica only)]
It is obtained by adding 5.3 g of SNOWTEX (registered trademark) -UP (Nissan Chemical Industry Co., Ltd., solid content 20 mass%, beaded (chain) silica particles) to 15.9 g of deionized water and stirring. 0.1 × 10 ³ mol / L sodium hydroxide was added dropwise to the mixture to adjust the pH to about 12. Thereafter, 0.0016 g of aminoethylaminopropyltrimethoxysilane (manufactured by Toray Dow Corning Co., Ltd., Z-6020) in 1.3 g of ethanol was added dropwise, and this was mixed with a mixture adjusted to a pH of about 12 for 14 hours. Stir to prepare silica dispersion 2C.

[Preparation of aqueous coating solution 9]
To silica dispersion 2C, 15.1 g of deionized water and 0.56 g of a 10 mass% aqueous solution of TRITON BG10 were added to prepare an aqueous coating liquid 9 (solid content: 2.78 mass%). The pH of the aqueous coating solution 9 was 9.3.

[Production of membrane sample]
A film sample was prepared in the same manner as in Example 1 except that the aqueous coating solution 1 used in Example 1 was changed to the aqueous coating solution 9. The final film thickness of the film sample was 195 nm.

(Comparative Example 8)
[Preparation of silica dispersion 3A (dispersion containing one kind of silica, only beaded silica)]
SNOWEX (registered trademark) -OXS (manufactured by Nissan Chemical Industries, Ltd., solid content 10 mass%, beaded (chain) silica particles) was used as the silica dispersion 3A.

[Preparation of aqueous coating solution 10]
17.8 g of deionized water, 5.15 g of ethanol, 0.60 g of 1% ethanol solution of aluminum bis (ethylacetoacetate) mono (acetylacetonate), polyethylene glycol monolauryl ether (the number of repetitions of ethylene oxide part 15) 0.94 g of 0.5 mass% aqueous solution of sodium, 0.43 g of 0.2 mass% aqueous solution of sodium di (2-ethylhexyl) sulfosuccinate, and SNOWTEX (registered trademark) -OXS (manufactured by Nissan Chemical Industries, Ltd., solid content) Aqueous coating solution 10 (solid content 1.68% by mass) was prepared by adding 5.04 g of 10% by mass, beaded (chain) silica particles) and stirring.

[Production of membrane sample]
A film sample was prepared in the same manner as in Example 1 except that the aqueous coating solution 1 used in Example 1 was changed to the aqueous coating solution 10. The final film thickness of the film sample was set to 200 nm.

-Evaluation of membrane samples-
Each film sample obtained above was evaluated for antireflection (AR), scratch resistance, antifouling property, and surface shape. The evaluation results are shown in Table 1 below.

[Antireflection (AR) properties]
The reflectivity of each film sample with light having a wavelength of 400 nm to 1100 nm was measured using an integrating sphere with an ultraviolet-visible infrared spectrophotometer (manufactured by JASCO Corporation, V-670).
At the time of reflectance measurement, a black tape was attached to the glass substrate surface on the back surface in order to suppress reflection on the back surface of the glass substrate having the film sample (the surface on which the glass substrate film was not formed). . The average reflectance is calculated from the reflectance of each wavelength at wavelengths of 400 to 1100 nm obtained by measurement, and the absolute value (| ΔR |) of the change in average reflectance with respect to the glass substrate on which no film is formed is expressed by the following formula: Calculated according to (1). In addition, | ΔR | is superior in antireflection (AR) property as the numerical value is higher.

| Average reflectance change ΔR | = | _{Average reflectance of base material after} R _{film formation−Average reflectance of} R _{base material} | Formula (1)

[Scratch resistance 1]
Using a rubbing tester under environmental conditions of a temperature of 25 ° C. and a relative humidity of 55%, the membrane surface of the membrane sample was subjected to a load of 50 g on steel wool (# 0000, manufactured by Nippon Steel Wool Co., Ltd.) at a speed of 1000 mm / min. The film surface after 10 reciprocating frictions was visually observed, and scratch resistance was evaluated according to the following evaluation criteria. In addition, as for the scratch resistance 1, AC is a tolerance | permissible_range.

-Evaluation criteria-
A: No scratches are visible on the film surface.
B: Scratches were not confirmed on the film surface, but a slight trace was confirmed.
C: Scratches are confirmed on the film surface, and the number of scratches is 1 to 20.
D: Scratches are confirmed on the film surface, and the number of scratches is 21 or more.

[Anti-fouling]
A natural ocher pigment (manufactured by Holbein Co., Ltd.) was uniformly dispersed on the membrane of the membrane sample and adhered, and then the back surface of the membrane sample was struck to remove the attached natural ocher pigment. This operation was repeated 20 times. Thereafter, the adhesion state of the natural ocher pigment was visually confirmed, and the antifouling property was evaluated according to the following evaluation criteria. In addition, as for antifouling property, AC is an acceptable range.

-Evaluation criteria-
A: The natural ocher pigment does not adhere to the surface of the membrane sample and is colorless and transparent.
B: Natural ocher pigment slightly adhered to the surface of the membrane sample, but is almost colorless and transparent.
C: Natural ocher pigment adheres to the entire surface of the membrane sample, and a decrease in transparency can be confirmed visually.
D: Natural ocher pigment adheres to the entire surface of the membrane sample and is almost opaque.

[Surface shape]
The surface of the film sample was visually observed, and the surface condition was evaluated according to the following evaluation criteria.
-Evaluation criteria-
Good: Interference unevenness is slightly seen and repellency is less than 10 pieces / 100 cm ² .
Defect: Interference unevenness is clearly confirmed, and repellency is 10/100 cm ² or more.

  From Table 1, it can be seen that the film samples of the examples are excellent in antireflection properties, scratch resistance, antifouling properties, and surface properties.

(Example 7)
[Membrane sample preparation]
The aqueous coating solution 1 in Example 1 was coated on a glass substrate using a bar coater to form a coating film. This coating film was dried in an oven at 150 ° C. for 1 minute to obtain a film sample without firing. The final film thickness of the film sample was 190 nm. Moreover, when the surface roughness Ra of the film sample was measured by the method described above, the surface roughness Ra was 20 nm or less.

(Comparative Example 9)
The aqueous coating solution 10 in Comparative Example 8 was coated on a glass substrate using a bar coater to form a coating film. This coating film was dried in an oven at 150 ° C. for 1 minute to obtain a film sample without firing. The final film thickness of the film sample was 175 nm.

About Example 7 and Comparative Example 9, as in Example 1, evaluation of antireflection property, antifouling property, and surface condition was performed. The evaluation results are shown in Table 2 below.
The scratch resistance was evaluated by the following scratch resistance 2 method.

[Scratch resistance 2]
Using a rubbing tester under environmental conditions of a temperature of 25 ° C. and a relative humidity of 55%, the membrane surface of the membrane sample was subjected to a load of 20 g on steel wool (# 0000, manufactured by Nippon Steel Wool Co., Ltd.) at a speed of 1000 mm / min. The film surface after 10 reciprocating frictions was visually observed, and scratch resistance was evaluated according to the following evaluation criteria. In addition, as for the scratch resistance 2, AC is a tolerance | permissible_range.

-Evaluation criteria-
A: No scratches are visible on the film surface.
B: Scratches were not confirmed on the film surface, but a slight trace was confirmed.
C: Scratches are confirmed on the film surface, and the number of scratches is 1 to 20.
D: Scratches are confirmed on the film surface, and the number of scratches is 21 or more.

  From Table 2, it can be seen that in Example 7, a film sample with good antireflection properties was obtained, and in comparison with Comparative Example 9, the film sample of Example 7 was excellent in scratch resistance.

Claims (23)

An aqueous coating having a pH of 1.5 to 3.5, comprising water, one kind of nonporous silica particles having an average primary particle diameter of 8 nm or less as a silica particle, and a surfactant. Applying a liquid to form a coating film;
A step of drying the coating film formed by coating;
The manufacturing method of the film | membrane containing this.   The method for producing a film according to claim 1, wherein the average primary particle diameter is 6 nm or less.   The method for producing a film according to claim 1 or 2, wherein the pH is 1.8 to 3.0.   The film production according to any one of claims 1 to 3, further comprising a step of baking the dried coating film at a temperature of 400 ° C to 800 ° C after the step of drying the coating film. Method.   The method for producing a film according to claim 4, wherein the baking is performed at a temperature of 500 ° C. or higher and 800 ° C. or lower.   The method for producing a film according to claim 4 or 5, wherein in the firing step, a particle connected body in which a plurality of nonporous silica particles are connected is formed by firing.   The method for producing a film according to claim 4, wherein the coating film after baking has a thickness of 50 nm to 350 nm. At least the coating film after drying has an absolute value of an average reflectance change ΔR at the time of 5 ° incidence in light having a wavelength of 400 nm to 1100 nm defined by the following formula (1): 2.0% or more. The manufacturing method of the film | membrane of any one of Claims 1-7.

| Average reflectance change ΔR | = | _{Average reflectance of base material after} R _{film formation−Average reflectance of} R _{base material} | Formula (1)
  The method for producing a film according to claim 8, wherein an absolute value of the average reflectance change ΔR is 2.5% or more.   An aqueous coating solution containing water, one kind of nonporous silica particles having an average primary particle diameter of 8 nm or less as silica particles, and a surfactant, and having a pH of 1.5 to 3.5.   The aqueous coating solution according to claim 10, wherein the average primary particle size is 6 nm or less.   The aqueous coating solution according to claim 10 or 11, wherein the pH is 1.8 to 3.0.   The aqueous coating solution according to any one of claims 10 to 12, wherein the surfactant is a nonionic surfactant.   A film containing one kind of nonporous silica particles having an average primary particle diameter of 8 nm or less as silica particles and a film thickness of 50 nm to 350 nm.   The film according to claim 14, wherein the average primary particle diameter is 6 nm or less. The film according to claim 14 or 15, wherein an absolute value of an average reflectance change ΔR at 5 ° incidence in light having a wavelength of 400 nm to 1100 nm defined by the following formula (1) is 2.0% or more. .

| Average reflectance change ΔR | = | _{Average reflectance of base material after} R _{film formation−Average reflectance of} R _{base material} | Formula (1)
  The film according to claim 16, wherein an absolute value of the average reflectance change ΔR is 2.5% or more.   The film according to any one of claims 14 to 17, wherein the nonporous silica particles are contained as a state of a particle connected body in which a plurality of nonporous silica particles are connected.   Furthermore, the film | membrane of any one of Claims 14-17 containing surfactant.   The film according to any one of claims 14 to 19, wherein the surface roughness Ra is 20 nm or less.   The laminated body which has a film | membrane manufactured by the manufacturing method of any one of Claims 1-9 on a base material, or the film | membrane of any one of Claims 14-20.   The laminate according to claim 21, wherein the substrate is a glass substrate.   The solar cell module provided with the laminated body of Claim 21 or Claim 22.