JP5965210B2 - Tempered glass substrate and solar cell module - Google Patents

Description

  The present invention relates to a tempered glass substrate and a solar cell module.

The protective member on the light-receiving surface side of the solar cell module is required to have both high transparency and mechanical strength, and conventionally, a tempered glass substrate has been widely proposed (for example, see Patent Document 1).
In general, as a method for strengthening a glass substrate, there is a quench strengthening method in which a glass plate is once heated to a high temperature and then rapidly cooled. When the glass is rapidly cooled, the temperature of the glass surface is suddenly lowered and becomes a glass state before thermal contraction, and a compressive stress layer is formed. On the other hand, since the heat dissipation is slow in the glass core layer, the temperature gradually decreases while shrinking to become a glass state. As a result, a stress strain is formed between the compressive stress layer and the core layer, resulting in a tempered glass.
The quenching strengthening method as described above is an excellent method with high productivity. However, when the glass substrate is thin, a large difference in cooling rate cannot be obtained in the cross-sectional direction, so that effective stress strain can be formed. It is known that it is difficult and tempered glass cannot be obtained (for example, refer to Patent Document 2). Therefore, glass with a thickness of 3 mm or more is usually used for the tempered glass substrate used in the solar cell module, which is a major cause of the large mass of the solar cell module.

The solar cell module is mainly transported by manpower at the time of installation, to reduce the cost of the mounting base for installing the solar power module, or to install the solar cell module on a low-strength roof, etc. For this reason, weight reduction is required.
In view of such a demand for weight reduction, for example, as a technique for producing a thin sheet tempered glass having a thickness of 2 mm or less, there is a chemical strengthening method, which is put into practical use as a technique for producing a cover glass for a display device such as a liquid crystal panel. (For example, see Patent Document 2 and Patent Document 3).
The chemical strengthening method of the glass is that the temperature of the glass does not generate distortion or less, and the antkari metal ion (typically lithium ion or sodium ion) having a small ionic radius on the glass plate surface is exchanged by ion exchange. In this method, a compressive stress layer is formed by exchanging ions (typically potassium ions).

On the other hand, the tempered glass substrate used in the solar cell module is required to have a property of preventing reflection of sunlight on the surface and transmitting more light in the solar cell module. Attempts are usually made to form an antireflection layer on the surface of a tempered glass substrate used in a solar cell module.
In order to suppress the reflection of sunlight on the surface of the tempered glass substrate, it is only necessary to reduce the difference in refractive index between air and the glass surface. Therefore, a layer having a lower refractive index (antireflection layer) is provided on the surface of the tempered glass substrate. A forming technique is disclosed (for example, see Patent Document 4 and Patent Document 5).

Japanese Patent Laid-Open No. 01-103882 JP 2011-84456 A JP 2011-190174 A JP 2002-182006 A JP 2011-111533 A

  However, when an antireflection layer is formed on the surface of a thin tempered glass substrate, in particular, a thin tempered glass substrate reinforced by the above-described chemical strengthening method, an effect of improving strength and an antireflection function on the surface can be obtained. However, satisfactory characteristics have not yet been obtained in practice, and improvements are required. That is, when exposed in a harsh environment for a long period of time, an increase in the haze value estimated to be caused by microcracks in the antireflection layer caused by the strain between the compression stress layer and the antireflection layer described above occurs. In order to reduce the light transmission and reduce the function of the solar cell module, improvement is required.

  Therefore, an object of the present invention is to provide a lightweight tempered glass substrate that effectively suppresses a decrease in light transmission due to the occurrence of microcracks, has excellent antireflection properties, and is suitable for solar cell module applications.

As a result of intensive studies to solve the above-mentioned problems, the present inventors are a tempered glass substrate in which an antireflection layer having a specific thickness is formed on a glass substrate having a specific thickness. The inventors have found that the above-described problems of the prior art can be solved by setting the ratio of the thickness and the thickness of the antireflection layer within a specific range, and the present invention has been completed.
That is, the present invention is as follows.

[1]
An inner layer, and a compressive stress layer formed on both outer sides of the inner layer;
An antireflection layer on the surface of at least one of the compression pressure layers on both outer sides of the inner layer; and
A tempered glass substrate comprising:
The antireflection layer is formed by forming a coating composition containing metal oxide fine particles, a binder, and polymer emulsion particles,
The tempered glass substrate has a thickness of 0.15 mm to 2 mm,
The thickness of the antireflection layer is 0.05 μm or more and 1 μm or less,
The ratio of the thickness of the antireflection layer to the thickness of the compressive stress layer (thickness / thickness compression stress layer of the antireflection layer) state, and are 0.001 to 0.1,
The haze after an environmental exposure test (exposure test using a sunshine weather meter (manufactured by Suga Test Instruments) (condition: black panel temperature 63 ° C., 18 minutes every 2 hours of rainfall) for 4000 hours) is 1.2 or less Tempered glass substrate.
[2]
The tempered glass substrate according to [1], wherein the compressive stress layer is formed by exchanging alkali metal ions on the glass surface.
[3]
[1] or [1], wherein a difference between a refractive index of the antireflection layer and a refractive index of the compressive stress layer (refractive index of the compressive stress layer−refractive index of the antireflection layer) is 0.05 or more and 0.4 or less. The tempered glass substrate according to [2].
[4]
The tempered glass substrate according to any one of [1] to [3], wherein a refractive index of the antireflection layer is 1.25 or more and 1.45 or less.
[5]
The compressive stress of the compressive stress layer is 250 MPa or more,
The tempered glass substrate according to any one of [1] to [4], wherein the inner layer has a tensile stress of 200 MPa or less.
[6]
A solar cell module comprising the tempered glass substrate according to any one of [1] to [5] .

  According to the present invention, there is provided a lightweight tempered glass substrate that effectively suppresses a decrease in light transmission due to the occurrence of microcracks, has excellent antireflection properties, and is suitable for solar cell module applications.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

[Tempered glass substrate]
The tempered glass substrate of this embodiment is
The inner layer,
A compressive stress layer formed on both outer sides of the inner layer;
An antireflection layer on the surface of at least one of the compression pressure layers on both outer sides of the inner layer; and
A tempered glass substrate comprising:
The tempered glass substrate has a thickness of 0.15 mm to 2 mm,
The thickness of the antireflection layer is 0.05 μm or more and 1 μm or less,
A tempered glass substrate, wherein the ratio of the thickness of the antireflection layer to the thickness of the compression stress layer (the thickness of the antireflection layer / the thickness of the compression stress layer) is 0.001 or more and 0.1 or less.

(Glass substrate)
The tempered glass substrate of this embodiment has a configuration in which a compressive stress layer is formed outside the inner layer by strengthening a predetermined glass substrate.
Although the glass substrate used as the material of the tempered glass substrate of this embodiment is not limited to the following, a glass substrate made of soda-lime glass is excellent in productivity and preferable. Among them, in the near-infrared wavelength region from the visible light region where the solar cell has high energy conversion sensitivity, a glass substrate with high light transmittance is more preferable, and the iron oxide content is less than that of ordinary soda-lime-based glass, So-called white plate glass is more preferable.

Glass substrate which is a material of the tempered glass preferably contains _{SiO 2, Al 2 O 3,} Na 2 O, K 2 O, MgO, and CaO as a component.
SiO ₂ is a main component that forms a skeleton of glass, and the content is preferably 50% by mass or more and 80% by mass or less from the balance of melting temperature that greatly affects the durability and productivity of glass, and 65% by mass. % To 75% by mass is more preferable.
Al ₂ O ₃ is a component that promotes ion exchange necessary for forming the compressive stress layer, and the content is preferably 1% by mass or more and 25% by mass or less from the balance of ion exchange performance and devitrification, More preferably, it is 3 mass% or more and 20 mass% or less.
Na ₂ O is a component that is a main component of ion exchange necessary for forming the compressive stress layer, and is a component that lowers the melt viscosity of the glass to improve the moldability of the glass and further improves the devitrification resistance. From the balance between the above performance and the thermal shock resistance resulting from the increase in thermal expansion coefficient, the content is preferably 5% by mass or more and 20% by mass or less, more preferably 8% by mass or more and 16% by mass or less. .
K ₂ O has the effect of promoting ion exchange, further lowers the melt viscosity of the glass, improves the moldability of the glass, and improves the devitrification resistance, and increases the above performance and thermal expansion coefficient. The content is preferably 10% by mass or less, more preferably 1% by mass or more and 5% by mass or less, from the balance with the thermal shock resistance due to.
MgO has the effect of improving the durability of the glass and improving the moldability by reducing the melt viscosity of the glass. The content is preferably 10% by mass or less, preferably 1% by mass or more and 7% by mass or less from the balance between the expression of these effects and the thermal shock resistance and devitrification caused by the increase in the coefficient of thermal expansion. More preferred.
CaO has the effect of improving the durability of the glass and improving the moldability by reducing the melt viscosity of the glass. The content is preferably 20% by mass or less, preferably 1% by mass or more and 15% by mass or less from the balance between the expression of these effects and the thermal shock resistance and devitrification caused by the increase of the thermal expansion coefficient. More preferred.

The glass substrate that is the material of the tempered glass substrate may contain iron oxide, which is mainly a raw material impurity, such as Fe ₂ O ₃ or FeO. In order to increase the light transmittance, the total iron oxide content is preferably 0.1% by mass or less in terms of Fe ₂ O ₃ . 0.05 mass% or less is more preferable, and 0.02 mass% or less is further more preferable. Further, the content of FeO is preferably 20 mol% or less with respect to the total iron oxide.
On the glass substrate, other metal oxides such as Li ₂ O, SrO, BaO, ZnO, Sn ₂ O, ZrO ₂ , B ₂ O ₃ , TiO ₂ , SO ₃ , and P ₂ O ₅ are allowed to transmit light. May be contained within a range that does not adversely affect performance such as property.
The glass substrate as a material of the tempered glass substrate of the present embodiment is not particularly limited, but can be manufactured by a method such as an overflow down-draw method, a down-draw method, a float method, a roll-out method, a press method, or a cast method. .

The thickness of the glass substrate used as the material of the tempered glass substrate of this embodiment is 0.1 mm or more and 2 mm or less. Preferably they are 0.2 mm or more and 1.5 mm or less, More preferably, they are 0.5 mm or more and 1.2 mm or less. By setting the thickness to 0.1 mm or more, the strength required as a glass substrate is obtained, and by setting the thickness to 2 mm or less, a lightweight glass substrate is obtained.
In addition, the thickness of the tempered glass substrate of this embodiment is 0.15 mm or more and 2 mm or less. Preferably it is 0.2 mm or more and 1.5 mm or less, more preferably 0.5 mm or more and 1,2 mm or less, and it is excellent in mechanical strength by being 0.15 mm or more, and 2.0 mm or less. A lightweight tempered glass substrate is obtained.

The tensile stress of the inner layer of the tempered glass substrate of this embodiment is preferably 200 MPa or less. 150 MPa or less is more preferable, and 100 MPa or less is more preferable. By setting the tensile stress to 200 MPa or less, it is preferable from the viewpoint of safety because no cracks are caused when a crack due to impact or the like develops inside the glass substrate.
The “inner layer of the tempered glass substrate” means a glass layer inside the compressive stress layer of the tempered glass substrate.

The refractive index of the glass substrate is preferably from 1.48 to 1.55, more preferably from 1.49 to 1.53, and still more preferably from 1.50 to 1.52.
By setting the refractive index to 1.48 or more and 1.55 or less, a tempered glass substrate with high productivity and light weight can be obtained.

(Compressive stress layer)
The compression pressure layer is formed as both outer layers of the inner layer, and exhibits a function of improving mechanical strength in the tempered glass substrate of the present embodiment.
Methods for forming the compressive stress layer include a physical strengthening method and a chemical strengthening method.
The tempered glass substrate of this embodiment preferably forms a compressive stress layer by a chemical tempering method.
The chemical strengthening method is a method in which alkali ions having a large ion radius are introduced into the surface of a glass substrate by ion exchange at a temperature at which the glass is not distorted.
For example, there is a method in which Na on the surface of the glass substrate, which is a material of the tempered glass substrate of the present embodiment, is ion exchanged with K.
If the compressive stress layer is formed by a chemical strengthening method, even if the thickness of the glass substrate as a material is thin, the strengthening treatment can be performed satisfactorily and a desired mechanical strength can be obtained.
The chemical strengthening method is not particularly limited as long as Na on the surface of the glass substrate and K in the molten salt can be ion-exchanged. For example, a method of immersing a glass plate in a heated potassium nitrate (KNO ₃ ) molten salt is exemplified. It is done.

As a method for forming a compressive stress layer having a desired compressive stress, although depending on the thickness of the glass substrate, there is a method of immersing the glass substrate in KNO ₃ molten salt at 400 to 550 ° C. for 2 to 20 hours. It is done.
The compressive stress of the compressive stress layer is preferably 250 MPa or more and 1500 MPa or less, more preferably 400 MPa or more and 1200 MPa or less, and further preferably 600 MPa or more and 1000 MPa or less. Practical mechanical strength can be obtained by setting the compressive stress to 250 MPa or more. On the other hand, by setting the compressive stress to 1500 MPa or less, the tensile stress of the inner layer of the tempered glass substrate can be suppressed to be small, and it is preferable from the viewpoint of safety without causing explosive destruction when a crack due to impact or the like propagates inside the glass substrate.
To increase the compressive stress in the compressive stress layer, a method of increasing the content of Al ₂ O ₃ , TiO ₂ , ZrO ₂ , MgO, ZnO, SnO ₂ , a method of reducing the content of SrO, BaO, ion exchange For example, a method for shortening the time required for reducing the temperature of the molten salt, and the like.

The thickness of the compressive stress layer is preferably 5 μm or more and 100 μm or less. 10 μm or more and 70 μm or less is more preferable, and 15 μm or more and 50 μm or less is more preferable.
Practical mechanical strength can be obtained by setting the thickness of the compressive stress layer to 5 μm or more.
By setting the thickness of the compressive stress layer to 100 μm or less, the tensile stress of the inner layer of the tempered glass substrate can be suppressed to be small, and when a crack due to impact or the like propagates inside the glass substrate, it is preferable for safety.

In order to thicken the compressive stress layer, a method of increasing the content of K ₂ O, P ₂ O ₅ , TiO ₂ , ZrO _{2 in} the glass substrate that is the material of the tempered glass substrate of the present embodiment, SrO in the glass substrate, Examples thereof include a method for reducing the content of BaO, a method for increasing the time required for ion exchange, and a method for increasing the temperature of the molten salt used for ion exchange.

  The refractive index of the compressive stress layer has a high mechanical strength in the tempered glass substrate of the present embodiment by setting the difference between the refractive index of the glass substrate that is the material of the tempered glass substrate of the present embodiment and substantially zero. It can be expressed. The refractive index of the compressive stress layer is preferably from 1.48 to 1.55, more preferably from 1.49 to 1.53, and still more preferably from 1.50 to 1.52.

(Antireflection layer)
The antireflection layer is formed on the surface of at least one of the compression pressure layers formed on both outer sides of the inner layer as described above, and reflects light on the surface of the tempered glass substrate of this embodiment. It has the function to reduce.
The antireflection layer may be formed on both surfaces of the tempered glass substrate, or may be formed only on one surface (light receiving surface side). If importance is attached to the economy, it should be formed on one side, and if it is important to improve the antireflection property even a little, it may be formed on both sides.
The antireflection layer can be formed by depositing a fluorine or other low refractive index material on the surface of the compression pressure layer described above.
Alternatively, the antireflection layer can be formed by using a material close to the composition of the glass substrate that is the material of the tempered glass substrate of the present embodiment and making the inside porous.
From the viewpoint of obtaining high adhesion between the antireflection layer and the compressive stress layer, and from the viewpoint of difficulty in attaching dirt after being placed in a harsh environment, the antireflection layer uses a material close to the composition of the glass substrate, and It is preferable to make the inside porous.
As a method of using a material close to the composition of the glass substrate and making the inside porous, for example, a coating composition containing a hydrolyzable metal compound is applied to a glass substrate having a compressive stress layer by a sol-gel method or the like. A hydrolyzable metal compound undergoes a hydrolysis reaction to form an amorphous metal oxide, forms a chemical bond with a glass substrate having a compressive stress layer, and then remains hydrolysable in the layer. A method of making the inside of the layer porous by dispersing groups, hydrolysis products, or residual solvent by heating or the like, or a coating composition containing metal oxide fine particles and a binder, between metal oxide fine particles And forming a film on a glass substrate having a compressive stress layer, leaving a void formed in the glass substrate, and a binder comprising metal oxide fine particles and metal oxide fine particles and a glass substrate having a compressive stress layer. And How to be bound to a solid, and a method of combining the two methods.

Examples of the metal in the hydrolyzable metal compound used in the coating composition include, but are not limited to, silicon, aluminum, titanium, zirconium, and tantalum. Silicon is preferable because of its low refractive index.
The hydrolyzable metal compound is a metal compound having a hydrolyzable group, and the hydrolyzable group is a functional group that generates a hydroxyl group by hydrolysis, and is not limited to the following, but a halogen atom, an alkoxy group , An acyloxy group, an amino group, a phenoxy group, an oxime group, and the like. From the viewpoint of availability and economy, an alkoxy group is preferable from the viewpoint of difficulty in coloring, an alkoxysilane is more preferable, and an alkoxy group in one molecule. Are more preferable, and alkoxysilanes having 4 or more alkoxy groups in one molecule are even more preferable.

  Examples of the alkoxysilanes include, but are not limited to, tetramethoxysilane, tetraethoxysilane, tetra (n-propoxy) silane, tetra (i-propoxy) silane, and tra (n-butoxy) silane. Tetraalkoxysilanes such as tetra (i-butoxy) silane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, trialkoxysilanes such as trimethoxysilane and triethoxysilane, methyltrimethoxysilane, methyltrimethoxysilane Ethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, isobutyltriethoxysilane, cyclohexyltrimethoxysilane, phenyltrimethoxysilane, phenyltriet Alkyl or aryltrialkoxysilanes such as silane, dialkoxysilanes such as dimethoxysilane and diethoxysilane, alkyldialkoxysilanes such as methyldimethoxysilane and methyldiethoxysilane, dimethyldimethoxysilane and dimethyldiethoxysilane Dialkyl dialkoxysilanes, bis (trimethoxysilyl) methane, bis (triethoxysilyl) methane, bis (trimethoxysilyl) ethane, bis (triethoxysilyl) ethane, 1,3-bis (trimethoxysilyl) propane, Bis (trialkoxysilyl) alkanes such as 1,3-bis (triethoxysilyl) propane, hydroxyalkyltrialkoxy such as 3-hydroxypropyltrimethoxysilane and 3-hydroxypropyltriethoxysilane Silanes are exemplified. Among these, tetraalkoxysilanes are preferable from the viewpoint of mechanical strength of the antireflection layer and availability.

Further, as the hydrolyzable metal compound, a partial hydrolysis condensate of tetraalkoxysilanes can also be preferably used. The partially hydrolyzed condensate of tetraalkoxysilanes is not limited to the following, but specifically, a partially hydrolyzed condensate of tetramethoxysilane (trade name “M silicate 51” Tama Chemical Co., Ltd. ), Trade name “MSI51” manufactured by Colcoat Co., Ltd.), trade names “MS51”, “MS56” manufactured by Mitsubishi Chemical Corporation), partially hydrolyzed condensate of tetoethoxysilane (trade name “Silicate 35”, “ Silicate 45 ”manufactured by Tama Chemical Industry Co., Ltd., trade names“ ESI40 ”,“ ESI48 ”manufactured by Colcoat Co., Ltd.), and a co-hydrolyzed condensate of tetramethoxysilane and tetraethoxysilane (trade name“ FR-3 ”) "Tama Chemical Industry Co., Ltd., trade name" EMSi48 "Colcoat Co., Ltd.) etc. can be used.
A hydrolysable metal compound can be used individually or in mixture of 2 or more types.

First, a method for forming a coating composition containing the hydrolyzable metal compound will be described as one method for forming the antireflection layer.
As the film forming method, a hydrolyzable metal compound, water, a solvent, and, if necessary, a catalyst are mixed, and a coating composition obtained by partially hydrolyzing and condensing the hydrolyzable metal compound is used for compression. A method of forming a thin film on a glass substrate having a stress layer and heating the glass substrate together can be mentioned.

As the solvent contained in the coating composition containing the hydrolyzable metal compound, an alcohol solvent is preferable. The alcohol-based solvent has a function of controlling the hydrolysis rate in the coating composition and improving the stability of the coating composition in addition to the function as a solvent.
Examples of alcohol solvents include, but are not limited to, monoalcohols such as methanol, ethanol, n-propanol, and i-propanol; diglycols such as ethyl cellosolve, butyl cellosolve, propyl cellosolve, and ethyl carbitol. Monoethers; and glycols such as ethylene glycol and propylene glycol.
Among these, monoalcohols are preferable because the effect of improving the stability of the coating composition is high.
Examples of solvents other than alcohols include ketone solvents such as acetone, ester solvents such as ethyl acetate, ether solvents such as tetrahydrofuran, ether ester solvents such as propylene glycol monoethyl ether acetate, and the like.
These solvents may be used alone or as a mixture of two or more.
The amount of the solvent varies depending on the coating method, the type of solvent, the amount of water, etc., but 0.1 part by mass or more is preferable for improving the stability of the coating composition with respect to 1 part by mass of the hydrolyzable metal compound. . 0.5 mass part or more and 500 mass parts or less are more preferable. 1 part by mass or more and 100 parts by mass or less is more preferable because it can improve the stability of the coating composition and can control the film thickness with little variation.

The water contained in the coating composition containing the hydrolyzable metal compound has a function of accelerating hydrolysis in the coating composition and after film formation in addition to the function as a solvent. It works to improve mechanical strength.
The amount of water varies depending on the coating method, the amount of the solvent, and the like, but it is preferably 0.1 parts by mass or more with respect to 1 part by mass of the hydrolyzable metal compound because the mechanical strength of the antireflection layer is improved. 0.5 mass part or more and 500 mass parts or less are more preferable. The amount is more preferably 1 part by mass or more and 100 parts by mass or less.

The catalyst contained in the coating composition containing the hydrolyzable metal compound has a function of accelerating the hydrolysis reaction of the hydrolyzable metal compound, and the metal hydroxide and hydrolyzable metal produced by hydrolysis. It has a function of promoting a condensation reaction with a compound.
Since the acid catalyst further promotes the hydrolysis reaction, the balance between the stability of the coating composition and the mechanical strength of the antireflection layer after film formation is preferable. More preferred are mineral acids such as hydrochloric acid and nitric acid, or acetic acid.
Since the basic catalyst further accelerates the condensation reaction, the stability of the coating composition may be impaired. When a basic catalyst is used, the environment in which the glass substrate is heated is, for example, a basic catalyst environment such as ammonia. It is preferable to heat with.
As for the compounding quantity of the catalyst in the coating composition containing a hydrolysable metal compound, 0.01 mass part or more is preferable with respect to 100 mass parts of hydrolyzable metal compounds. 0.05 parts by mass or more and 200 parts by mass or less is more preferable because the balance between the stability of the coating composition and the mechanical strength of the antireflection layer after film formation is good.

The method of forming a coating composition containing the hydrolyzable metal compound on a glass substrate having a compressive stress layer and finally forming a layer that will become an antireflection layer is limited to the following. However, for example, a method using a coater such as a spin coater, roll coater, spray coater, slit coater, curtain flow coater, dip coating method, etc., various methods such as flexographic printing, screen printing, gravure printing or curved surface printing. A printing method can be exemplified.
Depending on the surface state of the glass substrate having the compressive stress layer, the application of the coating solution may be poor, resulting in repelling or non-uniform film thickness. In such a case, it is preferable to wash or modify the substrate surface. Cleaning and modification methods include degreasing cleaning with alcohols such as ethanol or isopropanol, organic solvents such as acetone or hexane, cleaning with alkali or acid, surface polishing with an abrasive, ultrasonic cleaning, ultraviolet irradiation treatment, ultraviolet irradiation Examples of the method include ozone treatment and plasma treatment.

Next, the glass substrate having the compressive stress layer on which the coating composition containing the hydrolyzable metal compound is formed as described above is heated together with the glass substrate. As a result, the hydrolyzable metal compound undergoes a hydrolysis reaction and a condensation reaction to form an amorphous metal oxide, and a chemical bond is formed with the glass substrate having the compressive stress layer, and at the same time, it remains in the antireflection layer. Hydrolyzable groups, hydrolysis products, residual solvents, etc. that scatter out of the layer can make the antireflection layer porous.
When heated at a higher temperature, the organic component remaining in the antireflection layer burns, voids increase, and the refractive index can be further lowered.
The heating temperature is preferably 200 ° C. or higher and 700 ° C. or lower, more preferably 300 ° C. or higher and 600 ° C. or lower in order to obtain a porous structure without deformation of the glass substrate. In order not to relieve the stress of the compressive stress layer, 400 ° C. or higher and 500 ° C. or lower is more preferable.
The heating time of the glass substrate is preferably 10 seconds or more and 2 hours or less because both productivity and mechanical strength can be achieved.
When heating in a basic catalyst environment such as ammonia to control the hydrolysis / condensation reaction rate of the hydrolyzable metal compound and the scattering rate of the solvent and hydrolyzable organisms in the antireflection layer, Even at low temperatures, a porous structure can be formed. In this case, the heating temperature is preferably 40 ° C. or higher and 200 ° C. or lower. The heating time is preferably from 1 minute to 2 hours.

Next, as another method for forming the antireflection layer, a coating composition containing metal oxide fine particles and a binder is applied to the compression stress layer, leaving voids formed between the metal oxide fine particles. A method for forming a film on a glass substrate having the same will be described.
Examples of the metal oxide fine particles include, but are not limited to, silicon dioxide, aluminum oxide, antimony oxide, titanium oxide, indium oxide, tin oxide, zirconium oxide, lead oxide, iron oxide, magnesium oxide, Examples thereof include fine particles of metal oxides such as niobium oxide and cerium oxide.
Among them, silicon dioxide, aluminum oxide (alumina), antimony oxide, and complex oxides thereof having a large surface hydroxyl group are firmly bonded to a glass substrate having metal oxide fine particles or a binder or a compressive stress layer. Can be preferable. As the metal oxide fine particles, two or more kinds of metal oxide fine particles can be used in combination.

Examples of the form when using the metal oxide fine particles include powders, dispersions, and sols.
The dispersion or sol as used herein means that the metal oxide fine particle component has a concentration of 0.01 to 80% by mass, preferably 0.1 to 50% by mass in water and / or a hydrophilic organic solvent. It means a state of being dispersed as particles and / or secondary particles.
Examples of the hydrophilic organic solvent include, but are not limited to, alcohols such as ethylene glycol, butyl cellosolve, n-propanol, isopropanol, n-butanol, ethanol, and methanol, acetone, methyl ethyl ketone, and methyl isobutyl ketone. And ketones such as tetrahydrofuran, ethers such as dioxane, amides such as dimethylacetamide and dimethylformamide, dimethyl sulfoxide, nitrobenzene, and a mixture of two or more of these.
The particle diameter of the metal oxide fine particles is preferably 1 nm to 400 nm from the balance between productivity and light transmittance of the antireflection layer. In order to further improve the adhesion between the antireflection layer and the compressive stress layer and further reduce the refractive index of the antireflection layer, the particle diameter of the metal oxide fine particles is more preferably 1 nm to 100 nm. More preferably, it is 2 nm-80 nm, More preferably, it is 3 nm-50 nm.
Here, the particle diameter of the metal oxide fine particles is a number average particle diameter. When the particles are present in the form of primary particles, the primary particle diameter is obtained. When the particles are present in the form of aggregated particles, the particles are aggregated. This refers to the particle diameter (secondary particle diameter), and the particle diameter of the corresponding particle present in a transmission microscope (TEM) photograph taken by adjusting 100 to 200 metal oxide particles. It can be determined by obtaining an average value of (biaxial average diameter, that is, the average value of the minor axis and the major axis).

The metal oxide fine particles are preferably colloidal silica from the viewpoint of handleability.
Colloidal silica can be prepared and used by a sol-gel method, and a commercially available product can also be used.
For preparation by the sol-gel method, WernerStober et al; Colloidand Interface Sci. , 26, 62-69 (1968), Rickey D. et al. Badley et al; Lang muir 6, 792-801 (1990), Color Material Association Journal, 61 [9] 488-493 (1988). As commercial products, Snowtex (trademark) -O, Snowtex -OS, Snowtex -OL, Snowtex -OUP, Snowtex -UP, Snowtex -PS -SO, manufactured by Nissan Chemical Industries, Ltd., Asahi Denka Kogyo Co., Ltd. ) Acidite colloidal silica using water as a dispersion medium such as Adelite (trademark) AT-20Q manufactured by Adelite (trademark), Clevosol (trademark) 20H12 manufactured by Clariant Japan Co., Ltd., and Snowtex-20 manufactured by Nissan Chemical Industries, Ltd. SNOWTEX-30, SNOWTEX-C, SNOWTEX-C30, SNOWTEX-CM40, SNOWTEX-N, SNOWTEX-N30, SNOWTEX-K, SNOWTEX-XL, SNOWTEX-YL, SNOWTEX-ZL, Snowtex PS-M, Snowtex S-L, Snowtex-PS-S, etc., Adelite AT-20, Adelite AT-30, Adelite AT-20N, Adelite AT-30N, Adelite AT-20A, Adelite AT-30A, Adelite manufactured by Asahi Denka Kogyo Co., Ltd. AT-40, Adelite AT-50 etc., Clariant Japan Co., Ltd. clebosol 30R9, clebosol 30R50, clevosol 50R50 etc., DuPont Ludox (trademark) HS-40, Ludox HS-30, Ludox LS, Ludox SM-30 etc. And basic colloidal silica stabilized by the addition of alkali metal ions, ammonium ions, amines and the like using water as a dispersion medium.
Colloidal silica using a water-soluble solvent as a dispersion medium includes MA-ST-M (methanol dispersion type having a particle size of 20 to 25 nm) and IPAST (isopropyl having a particle size of 10 to 15 nm) manufactured by Nissan Chemical Industries, Ltd. Alcohol dispersion type), EG-ST (ethylene glycol dispersion type with particle diameter of 10 to 15 nm), EG-ST-ZL (ethylene glycol dispersion type with particle diameter of 70 to 100 nm), NPC-ST (particle diameter of 10 to 10 nm) And 15 nm ethylene glycol monopropyl ether dispersion type).
These colloidal silicas may be used alone or in combination.
As a minor component, alumina, sodium aluminate or the like may be included.
Colloidal silica may contain an inorganic base (such as sodium hydroxide, potassium hydroxide, lithium hydroxide, or ammonia) or an organic base (such as tetramethylammonium) as a stabilizer.

The binder is not limited to the following, but a metal compound having a hydrolyzable group, that is, a hydrolyzable metal compound is preferable, and hydrolysis using silicon, aluminum, titanium, zirconium, or tantalum as a metal. A metal compound having a functional group is more preferable, and a silicon compound having a hydrolyzable group is more preferable from the viewpoints of availability and economical efficiency and a low refractive index.
The term “hydrolyzable group” as used herein refers to a functional group that generates a hydroxyl group upon hydrolysis, and includes, for example, a halogen group, an alkoxy group, an acyloxy group, an amino group, a phenoxy group, an oxime group, and the like. From the viewpoints of economic efficiency and difficulty in coloring, alkoxy groups are preferred, alkoxysilanes are more preferred, alkoxysilanes having 3 or more alkoxy groups in one molecule are more preferred, and alkoxy groups are 4 in one molecule. Even more preferred are alkoxysilanes having at least one.

  Examples of the alkoxysilanes include, but are not limited to, tetramethoxysilane, tetraethoxysilane, tetra (n-propoxy) silane, tetra (i-propoxy) silane, and tra (n-butoxy) silane. Tetraalkoxysilanes such as tetra (i-butoxy) silane, tetra-sec-butoxysilane and tetra-tert-butoxysilane; trialkoxysilanes such as trimethoxysilane and triethoxysilane; methyltrimethoxysilane, methyltri Ethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, isobutyltriethoxysilane, cyclohexyltrimethoxysilane, phenyltrimethoxysilane, phenyltriet Alkyl or aryltrialkoxysilanes such as silane; dialkoxysilanes such as dimethoxysilane and diethoxysilane; alkyldialkoxysilanes such as methyldimethoxysilane and methyldiethoxysilane; dimethyldimethoxysilane and dimethyldiethoxysilane Dialkyl dialkoxysilanes; bis (trimethoxysilyl) methane, bis (triethoxysilyl) methane, bis (trimethoxysilyl) ethane, bis (triethoxysilyl) ethane, 1,3-bis (trimethoxysilyl) propane, Bis (trialkoxysilyl) alkanes such as 1,3-bis (triethoxysilyl) propane; Hydroxyalkyltrialkoxy such as 3-hydroxypropyltrimethoxysilane and 3-hydroxypropyltriethoxysilane Silanes and the like. In particular, tetraalkoxysilanes are preferable from the viewpoint of mechanical strength of the antireflection layer and availability.

Moreover, the partial hydrolysis-condensation product of the said tetraalkoxysilane can also be used preferably.
The partial hydrolysis-condensation product of the tetraalkoxysilanes is not limited to the following. For example, a partial hydrolysis-condensation product of tetramethoxysilane (trade name “M silicate 51” manufactured by Tama Chemical Industries, Ltd. , Trade name “MSI51” manufactured by Colcoat Co., Ltd.), trade names “MS51”, “MS56” manufactured by Mitsubishi Chemical Corporation), partially hydrolyzed condensates of tetoethoxysilane (trade names “silicate 35”, “silicate 45”) “Tama Chemical Industry Co., Ltd., trade names“ ESI40 ”,“ ESI48 ”manufactured by Colcoat Co., Ltd.) and co-hydrolyzed condensate of tetramethoxysilane and tetraethoxysilane (trade name“ FR-3 ”Tama) Chemical Industry Co., Ltd. product name "EMSi48" Colcoat Co., Ltd.) etc. are mentioned.
The various binders described above may be used alone or as a mixture of two or more.

  When the coating composition containing the metal oxide fine particles and the binder used for forming the antireflection layer described above contains polymer emulsion particles, it can relieve stress such as temperature change in the use environment. This is preferable because the occurrence of cracks in the antireflection layer can be suppressed.

  The compounding ratio of each component of the coating composition containing the metal oxide fine particles and the binder described above for forming the antireflection layer is based on 100 parts by mass of the metal oxide fine particles. The blending amount of the adhering material is preferably 1 part by mass or more and 200 parts by mass or less because it is possible to achieve both good mechanical strength and a low refractive index of the antireflection layer. Moreover, it is more preferable to set it as 5 mass parts or more and 100 mass parts or less because stronger adhesive force of an antireflection layer and a compressive stress layer can be expressed. More preferably, it is 20 parts by mass or more and 80 parts by mass or less.

Examples of the polymer emulsion particles include, but are not limited to, for example, a functional group-containing vinyl monomer, a vinyl group-containing hydrolyzable silicon compound, and other vinyl monomers. Examples include polymer emulsion particles obtained by polymerization in the presence.
Examples of the functional group-containing vinyl monomer include, but are not limited to, a hydroxyl group-containing vinyl monomer, a carboxyl group-containing vinyl monomer, an amide group-containing vinyl monomer, and an amino group-containing vinyl monomer. Examples thereof include monomers and ether group-containing vinyl monomers.
Examples of the hydroxyl group-containing vinyl monomer include, but are not limited to, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like. Hydroxyalkyl (meth) acrylates; Hydroxyl-containing vinyl ethers such as 2-hydroxyethyl vinyl ether and 4-hydroxybutyl vinyl ether; Hydroxyl-containing allyl ethers such as 2-hydroxyethyl allyl ether; Polyoxyls such as diethylene glycol mono (meth) acrylate Examples include alkylene glycol mono (meth) acrylates; adducts of the above-mentioned various hydroxyl group-containing vinyl monomers and lactones such as ε-caprolactone.

  Examples of the carboxyl group-containing vinyl monomer include, but are not limited to, for example, (meth) acrylic acid, 2-carboxyethyl (meth) acrylate, crotonic acid, itaconic acid, maleic acid, or fumaric acid. Unsaturated carboxylic acids such as monomethyl itaconate, mono-n-butyl itaconate, monomethyl maleate, mono-n-butyl maleate, monomethyl fumarate, mono-n-butyl fumarate and the like 1 Monoesters with monohydric alcohols; monovinyl esters of saturated dicarboxylic acids such as monovinyl adipate and monovinyl succinate; anhydrides of saturated polycarboxylic acids such as succinic anhydride, glutaric anhydride, phthalic anhydride and trimellitic anhydride Products of addition reaction of various hydroxyl group-containing vinyl monomers listed above; Monomer and the like obtained by addition reaction of a carboxyl group-containing monomers and the lactones of ε- caprolactone.

  Examples of the amide group-containing vinyl monomer include, but are not limited to, N-methylacrylamide, N-methylmethacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, N, N- Dimethylmethacrylamide, N, N-diethylacrylamide, N-ethylmethacrylamide, N-methyl-N-ethylacrylamide, N-methyl-N-ethylmethacrylamide, N-isopropylacrylamide, Nn-propylacrylamide, N- Isopropylmethacrylamide, Nn-propylmethacrylamide, N-methyl-Nn-propylacrylamide, N-methyl-N-isopropylacrylamide, N-acryloylpyrrolidine, N-methacryloylpyrrolidine, N-acryloyl Piperidine, N-methacryloylpiperidine, N-acryloylhexahydroazepine, N-acryloylmorpholine, N-methacryloylmorpholine, N-vinylpyrrolidone, N-vinylcaprolactam, N, N'-methylenebisacrylamide, N, N'-methylenebis Examples include methacrylamide, N-vinylacetamide, diacetone acrylamide, diacetone methacrylamide, N-methylol acrylamide, N-methylol methacrylamide and the like.

  Examples of the amino group-containing vinyl monomer include, but are not limited to, 2-dimethylaminoethyl (meth) acrylate, 2-diethylaminoethyl (meth) acrylate, 2-di-n-propylamino. Tertiary amino group-containing (meth) acryl such as ethyl (meth) acrylate, 3-dimethylaminopropyl (meth) acrylate, 4-dimethylaminobutyl (meth) acrylate or N- [2- (meth) acryloyloxy] ethylmorpholine Acid esters; tertiary amino group-containing aromatic vinyl monomers such as vinylpyridine and N-vinylcarbazole N-vinylquinoline; N- (2-dimethylamino) ethyl (meth) acrylamide, N- (2- Diethylamino) ethyl (meth) acrylamide, N- (2-di-n-propylamino) 3) such as ethyl (meth) acrylamide, N- (3-dimethylamino) propyl (meth) acrylamide, N- (4-dimethylamino) butyl (meth) acrylamide or N- [2- (meth) acrylamide] ethylmorpholine Secondary amino group-containing (meth) acrylamides; N- (2-dimethylamino) ethylcrotonic acid amide, N- (2-diethylamino) ethylcrotonic acid amide, N- (2-di-n-propylamino) ethylcrotonic acid Tertiary amino group-containing crotonic acid amides such as amide, N- (3-dimethylamino) propylcrotonic acid amide or N- (4-dimethylamino) butylcrotonic acid amide; 2-dimethylaminoethyl vinyl ether, 2-diethylaminoethyl Vinyl ether, 3-dimethylaminopropyl vinyl ether The like tertiary amino group-containing vinyl ethers such as 4-dimethylamino-butyl vinyl ether.

Examples of the ether group-containing vinyl monomer include, but are not limited to, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene higher fatty acid ester, polyoxyethylene / polyoxypropylene Examples include vinyl ethers having various polyether chains such as block copolymers in the side chain; vinyl monomers such as allyl ethers or (meth) acrylic acid esters.
As specific examples, Bremer PE-90, PE-200, PE-350, PME-100, PME-200, PME-400, AE-350 [above, manufactured by NOF Corporation], MA-30, MA- 50, MA-100, MA-150, RA-1120, RA-2614, RMA-564, RMA-568, RMA-1114, MPG130-MA [above, manufactured by Nippon Emulsifier Co., Ltd.].

The various functional group-containing vinyl monomers described above may be used alone or in combination of two or more.
By having the above-mentioned various functional group-containing vinyl monomers, the polymer emulsion particles form chemical bonds or hydrogen bonds with the metal oxide fine particles and the binder, and the mechanical strength and low refractive index of the antireflection layer are high. It is preferable to contribute to the coexistence of the above. From this viewpoint, it is preferable to use an amide group-containing vinyl monomer as the functional group-containing vinyl monomer.
The above-described various functional group-containing vinyl monomers form a chemical bond or a hydrogen bond with the metal oxide fine particles and the binder by making the amount to 5% by mass or more with respect to 100% by mass of the polymer emulsion particles, thereby reflecting This can contribute to both the strong mechanical strength of the prevention layer and the low refractive index, which is preferable. 10 mass% or more and 80 mass% or less are more preferable, and 15 mass% or more and 60 mass% or less are still more preferable from a viewpoint of polymerization stability.

Examples of the vinyl group-containing hydrolyzable silicon compound used for polymerizing the polymer emulsion particles include, but are not limited to, 3- (meth) acryloxypropyltrimethoxysilane, 3- ( Meth) acryloxypropyltriethoxysilane, 3- (meth) acryloyloxypropylmethyldimethoxysilane, 3- (meth) acryloyloxypropyltri-n-propoxysilane, 3- (meth) acryloyloxypropyltriisopropoxysilane, vinyl Examples thereof include silane coupling agents having a vinyl polymerizable group such as trimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, and 2-trimethoxysilylethyl vinyl ether.
These vinyl group-containing hydrolyzable silicon compounds may be used alone or in combination of two or more.
By having the vinyl group-containing hydrolyzable silicon compound, the polymer emulsion particles form a chemical bond with the metal oxide fine particles and the binder, contributing to both strong mechanical strength and low refractive index of the antireflection layer. It is preferable.
The vinyl group-containing hydrolyzable silicon compound is preferably 50% by mass or less with respect to 100% by mass of the polymer emulsion particles from the viewpoint of polymerization stability. By setting the content to 0.1% by mass or more and 20% by mass or less, the polymer emulsion particles form a chemical bond with the metal oxide fine particles and the binder, thereby achieving both the strong mechanical strength of the antireflection layer and a low refractive index. More preferably, 0.5 mass% or more and 10 mass% or less are still more preferable.

Examples of the other vinyl monomer used for polymerizing the polymer emulsion particles include, but are not limited to, methyl acrylate, ethyl acrylate, isopropyl acrylate, acrylic acid-n- Acrylic acid esters such as butyl and 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, methacrylic acid-n-butyl, methacrylic acid isobutyl, methacrylic acid-n-hexyl, methacrylic acid cyclohexyl, methacrylic acid Methacrylic acid esters such as lauryl acid; aromatic vinyl monomers such as styrene and vinyltoluene.
These other vinyl monomers may be used alone or in combination of two or more.
The other vinyl monomer is preferably from 1% by mass to 80% by mass with respect to 100% by mass of the polymer emulsion particles from the viewpoint of polymerization stability. 5 mass% or more and 50 mass% or less are more preferable, and 10 mass% or more and 30 mass% or less are more preferable.

Examples of the emulsifier used for polymerizing the polymer emulsion particles include, but are not limited to, alkylbenzene sulfonic acid, alkyl sulfonic acid, alkyl sulfosuccinic acid, polyoxyethylene alkyl sulfuric acid, and polyoxyethylene alkyl. Acidic emulsifiers such as arylsulfuric acid and polyoxyethylene distyrylphenyl ether sulfonic acid; alkali metal (Li, Na, K etc.) salts of acidic emulsifiers, ammonium salts of acidic emulsifiers, anionic surfactants such as fatty acid soaps; alkyltrimethyl Cationic surfactants such as quaternary ammonium salts such as ammonium bromide, alkylpyridinium bromide, imidazolinium laurate, pyridinium salt, imidazolinium salt type, etc .; polyoxyethylene alkylaryl ether, polyo Shi sorbitan fatty acid esters, polyoxyethylene polyoxypropylene block copolymer, nonionic surfactants such as polyoxyethylene distyryl phenyl ether.
These may be used alone or in combination of two or more.

As the emulsifier, it is preferable to use a reactive emulsifier having radical polymerizability from the viewpoint of improving the water dispersion stability of the polymer emulsion particles and improving the stain resistance of the antireflection layer.
Examples of the reactive emulsifier include, but are not limited to, for example, vinyl monomers having a sulfonic acid group or a sulfonate group, vinyl monomers having a sulfate ester group, and alkali metal salts or ammonium salts thereof. And vinyl monomers having a nonionic group such as polyoxyethylene, and vinyl monomers having a quaternary ammonium salt.

  Examples of the vinyl monomer having a sulfonic acid group or a sulfonate group include, but are not limited to, for example, a radical polymerizable double bond, and an ammonium salt, a sodium salt, or a sulfonic acid group. Alkyl group having 1 to 20 carbon atoms, alkyl ether group having 2 to 4 carbon atoms, polyalkyl ether group having 2 to 4 carbon atoms, phenyl group, naphthyl group partially substituted with a substituent such as potassium salt And a compound having a substituent selected from the group consisting of a succinic acid group, a vinyl sulfonate compound having a vinyl group to which a substituent is bonded, such as an ammonium salt, sodium salt or potassium salt of a sulfonic acid group. .

  Examples of the vinyl monomer having a sulfate group include, but are not limited to, for example, a radical polymerizable double bond, and an ammonium salt, sodium salt, or potassium salt of a sulfate group. The alkyl group having 1 to 20 carbon atoms, the alkyl ether group having 2 to 4 carbon atoms, the polyalkyl ether group having 2 to 4 carbon atoms, the phenyl group, and the naphthyl group, which are partially substituted by such substituents Examples thereof include compounds having a substituent selected from the group.

The succinic acid group having a radical polymerizable double bond and partially substituted with a substituent such as an ammonium salt, sodium salt or potassium salt of a sulfonic acid group is not limited to the following. For example, allylsulfosuccinate can be mentioned.
More specifically, for example, Eleminol JS-2 (trade name) (manufactured by Sanyo Chemical Co., Ltd.), Latemuru S-120, S-180A or S-180 (trade name) (manufactured by Kao Corporation), etc. Can do.
In addition, the alkyl ether group having 2 to 4 carbon atoms or carbon having the radical polymerizable double bond and partially substituted with a group which is an ammonium salt, sodium salt or potassium salt of a sulfonic acid group Specific examples of the compound having a polyalkyl ether group of 2 to 4 include, for example, Aqualon HS-10 or KH-1025 (trade name) (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adekari Soap SE-1025N or SR. -1025 (trade name) (manufactured by Asahi Denka Kogyo Co., Ltd.).

  The vinyl monomer having a nonionic group is not limited to the following, and examples thereof include α- [1-[(allyloxy) methyl] -2- (nonylphenoxy) ethyl] -ω-hydroxy. Polyoxyethylene (trade names: Adeka Soap NE-20, NE-30, NE-40, etc., manufactured by Asahi Denka Kogyo Co., Ltd.), polyoxyethylene alkylpropenyl phenyl ether (trade names: Aqualon RN-10, RN- 20, RN-30, RN-50, etc., manufactured by Dai-ichi Pharmaceutical Co., Ltd.).

  The emulsifier used for polymerizing the polymer emulsion particles is preferably 10% by mass or less with respect to 100% by mass of the polymer emulsion particles from the viewpoint of difficulty in staining the antireflection layer. 0.001 mass% or more and 7 mass% or less are more preferable from a viewpoint of superposition | polymerization stability, and 0.01 mass% or more and 5 mass% or less are still more preferable.

The polymer emulsion particles can be polymerized in the presence of a hydrolyzable silicon compound containing no vinyl group.
The hydrolyzable silicon compound containing no vinyl group forms a chemical bond by a condensation reaction with the reaction residue of the vinyl group-containing hydrolyzable silicon compound in the polymer emulsion particles during the polymerization reaction of the polymer emulsion, It forms a hydrogen bond with the reaction residue of the group-containing vinyl monomer, increases the degree of crosslinking in the polymer emulsion particles, and further increases the amount of inorganic substances in the polymer emulsion particles, resulting in high mechanical strength. Since an antireflection layer excellent in heat resistance can be formed, it is preferable to polymerize the polymer emulsion particles in the presence of a hydrolyzable silicon compound not containing a vinyl group.

  The hydrolyzable silicon compound containing no vinyl group used here is not limited to the following, but examples include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetra Tetraalkoxysilanes such as n-butoxysilane; methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane , Isopropyltriethoxysilane, n-butyltrimethoxysilane, n-butyltriethoxysilane, n-pentyltrimethoxysilane, n-hexyltrimethoxysilane, n-heptyltrimethoxysilane, n-octyl Limethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloro Propyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-hydroxy Ethyltrimethoxysilane, 2-hydroxyethyltriethoxysilane, 2-hydroxypropyltrimethoxysilane, 2-hydroxypropyltriethoxysilane, 3-hydroxypropyltrimethyl Xysilane, 3-hydroxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-glycidoxypropyl Trimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 3- (meth) acrylic Oxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloyloxypropyltri-n-propoxysilane, 3- (meth) acryloyloxypropyltrii Trialkoxysilanes such as sopropoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane; dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, di-n-propyldimethoxy Silane, di-n-propyldiethoxysilane, diisopropyldimethoxysilane, diisopropyldiethoxysilane, di-n-butyldimethoxysilane, di-n-butyldiethoxysilane, di-n-pentyldimethoxysilane, di-n-pentyl Diethoxysilane, di-n-hexyldimethoxysilane, di-n-hexyldiethoxysilane, di-n-heptyldimethoxysilane, di-n-heptyldiethoxysilane, di-n-octyldimethoxysilane, di Dialkoxysilanes such as n-octyldiethoxysilane, di-n-cyclohexyldimethoxysilane, di-n-cyclohexyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, 3- (meth) acryloyloxypropylmethyldimethoxysilane And monoalkoxysilanes such as trimethylmethoxysilane and trimethylethoxysilane.

As the hydrolyzable silicon compound not containing a vinyl group, a silicon alkoxide having a phenyl group (for example, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, etc.) can be used. When a silicon alkoxide having a phenyl group is used, the polymerization stability in the presence of water and an emulsifier is good, which is preferable.
Furthermore, as the hydrolyzable silicon compound containing no vinyl group, a silane coupling agent having a thiol group can be used. Examples of the silane coupling agent having a thiol group include 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane.
Moreover, the hydrolyzable silicon compound not containing the vinyl group may be a hydrolysis / condensation reaction product of the hydrolyzable silicon compound described above.
The hydrolyzable silicon compound containing no vinyl group may be used alone or in combination of two or more.
The hydrolyzable silicon compound containing no vinyl group is preferably 80 parts by mass or less with respect to 100 parts by mass of the polymer emulsion particles from the viewpoint of polymerization stability. By making the amount between 0.01 parts by weight and 60 parts by weight, a combination of strong mechanical strength and low refractive index of the antireflection layer can be achieved by forming a chemical bond between the polymer emulsion particles and the metal oxide fine particles and the binder. More preferably, 0.05 parts by weight or more and 40 parts by weight or less.

The polymer emulsion particles can be obtained by polymerization in the presence of water as described above.
That is, the polymer emulsion particles can be obtained by polymerizing the above-described components using water as a dispersion medium. The amount of water at the time of polymerization is preferably 0.5 parts by mass or more and 500 parts by mass or less with respect to 1 part by mass of the polymer emulsion particles.

The polymer emulsion particles are preferably polymerized in the presence of a catalyst such as a hydrolysis reaction catalyst or a radical polymerization catalyst.
Examples of the hydrolysis catalyst include, but are not limited to, hydrogen halides such as hydrochloric acid and hydrofluoric acid; carboxylic acids such as acetic acid, trichloroacetic acid, trifluoroacetic acid, and lactic acid; sulfuric acid and p-toluene. Sulfonic acids such as sulfonic acid; acidic emulsifiers such as alkylbenzenesulfonic acid, alkylsulfonic acid, alkylsulfosuccinic acid, polyoxyethylene alkylsulfuric acid, polyoxyethylene alkylarylsulfuric acid, polyoxyethylene distyrylphenyl ether sulfonic acid; acidic or weak Acidic inorganic salts, acidic compounds such as phthalic acid, phosphoric acid, nitric acid; sodium hydroxide, potassium hydroxide, sodium methylate, sodium acetate, tetramethylammonium chloride, tetramethylammonium hydroxide, tributylamine, diazabicycl Basic compounds such as undecene, ethylenediamine, diethylenetriamine, ethanolamines, γ-aminopropyltrimethoxysilane, γ- (2-aminoethyl) -aminopropyltrimethoxysilane; such as dibutyltin octylate, dibutyltin dilaurate A tin compound etc. can be mentioned.
As the hydrolysis catalyst, acidic emulsifiers are preferable from the viewpoint of dispersion stability of the polymer emulsion particles in water, alkylbenzenesulfonic acid having 5 to 30 carbon atoms is more preferable, and dodecylbenzenesulfonic acid is further preferable.

The radical polymerization catalyst is not limited to the following, but for example, water-soluble or oil-soluble persulfates, peroxides, azobis compounds and the like are preferably used. Specifically, for example, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, t-butyl hydroperoxide, t-butyl peroxybenzoate, 2,2-azobisisobutyronitrile, 2,2 -Azobis (2-diaminopropane) hydrochloride, 2,2-azobis (2,4-dimethylvaleronitrile) and the like.
When acceleration of the polymerization rate and polymerization at a low temperature of 70 ° C. or lower are desired, it is advantageous to use a reducing agent such as sodium bisulfite, ferrous chloride, ascorbate, or longalite in combination with the radical polymerization catalyst. is there.
A catalyst may be used independently and may use 2 or more types together.
It is preferable to use at least one radical polymerization catalyst.
The amount of the catalyst used is preferably 0.001 to 5 parts by mass with respect to 100 parts by mass of the polymer emulsion particles.

The polymer emulsion particles can be polymerized in the presence of a chain transfer agent such as alkyl mercaptan and a water-soluble polymer such as polyvinyl alcohol.
Thereby, the effect of reducing the unreacted vinyl monomer and the effect of improving the dispersion stability of the polymer emulsion particles in water are obtained.

As a method for obtaining the polymer emulsion particles, so-called emulsion polymerization in which the emulsifier is polymerized in the presence of a sufficient amount of water to form micelles is suitable.
Examples of the emulsion polymerization method include the functional group-containing vinyl monomer, the vinyl group-containing hydrolyzable silicon compound, the other vinyl monomer, and, if necessary, the hydrolyzable silicon compound. The reaction raw materials are added as they are or in an emulsified state, all at once, divided or continuously into a reaction vessel, and in the presence of the catalyst, under atmospheric pressure, or preferably under a pressure of 10 MPa or less, 30 The method of superposing | polymerizing at the reaction temperature of 150 degreeC-150 degreeC is mentioned.
Furthermore, when performing the emulsion polymerization, it is preferable to use a seed polymerization method from the viewpoint of appropriately growing or controlling the particle diameter.
The seed polymerization method is a method in which emulsion particles (seed particles) are previously present in an aqueous phase for polymerization. The pH in the polymerization system when performing the seed polymerization method is preferably 1.0 to 10.0, more preferably 1.0 to 6.0. The pH can be adjusted using a disodium phosphate, borax, or a pH buffer such as sodium bicarbonate or ammonia.

  The polymer emulsion particles preferably have a core / shell structure. As a method for forming the core / shell structure, multistage emulsion polymerization in which the emulsion polymerization is performed in multiple stages is very useful.

  As the multistage emulsion polymerization, for example, as a first step, in the presence of an emulsifier and water, a functional group-containing vinyl monomer, a vinyl group-containing hydrolyzable silicon compound, other vinyl monomers, and other as required At least one selected from reaction raw materials such as hydrolyzable silicon compounds is polymerized to form seed particles, and in the second stage, in the presence of the seed particles, functional group-containing vinyl monomer, vinyl group-containing A preferred method is a two-stage polymerization method in which at least one selected from reaction raw materials such as a hydrolyzable silicon compound, other vinyl monomers, and hydrolyzable silicon compounds is added and polymerized. Such a multistage emulsion polymerization method is also suitable from the viewpoint of polymerization stability.

  In the two-stage polymerization method, the ratio of the mass of the reaction raw material used in the first stage (M1) and the mass of the reaction raw material added in the second stage (M2) is from the viewpoint of polymerization stability. Preferably (M1) / (M2) = 9/1 to 1/9, more preferably 8/2 to 2/8.

The particle diameter of the polymer emulsion particles is preferably 10 nm to 800 nm from the balance between productivity and light transmittance of the antireflection layer. In order to further improve the adhesion between the antireflection layer and the compressive stress layer and further reduce the refractive index of the antireflection layer, the particle diameter of the polymer emulsion particles is more preferably 10 nm to 100 nm, and even more preferably 20 nm to 80 nm.
Here, the particle diameter is a number average particle diameter. When the particles are present in the form of primary particles, the primary particle diameter is used. When the particles are present in the form of aggregated particles, the aggregate particle diameter (secondary particles is used). Diameter), and the particle diameter of the corresponding particle (biaxial average diameter, present in a transmission microscope (TEM) photograph taken by adjusting so that 100 to 200 particles of the polymer emulsion are captured). That is, it can be determined by obtaining an average value of the average value of the minor axis and the major axis.

  The blending amount of the polymer emulsion particles is preferably 100 parts by mass or less with respect to 100 parts by mass of the metal oxide fine particles constituting the coating composition because it is possible to form an antireflection layer that is difficult to stain. By making it 10 parts by mass or more and 70 parts by mass or less, there is an effect of reducing the strain between the compressive stress layer and the antireflection layer and suppressing the occurrence of microcracks, which can suppress the haze value. More preferred. 25 parts by mass or more and 50 parts by mass or less are more preferable.

The coating composition containing the metal oxide fine particles and the binder may contain other additives depending on the application and usage method.
Other additives include, but are not limited to, for example, thickeners, leveling agents, thixotropic agents, antifoaming agents, freeze stabilizers, matting agents, crosslinking reaction catalysts, pigments, curing catalysts. , Crosslinking agent, filler, anti-skinning agent, dispersant, wetting agent, light stabilizer, antioxidant, UV absorber, rheology control agent, antifoaming agent, film-forming aid, rust inhibitor, dye, plastic An agent, a lubricant, a reducing agent, an antiseptic, an antifungal agent, a deodorant, an anti-yellowing agent, an antistatic agent, a charge control agent, or the like can be blended.

  As a method of forming the antireflection layer using the coating composition containing the metal oxide fine particles and the binder described above, each component constituting the above-mentioned coating composition, water, a solvent, and further if necessary A coating composition obtained by mixing a catalyst and partially hydrolyzing and condensing a hydrolyzable group contained in a binder or the like is formed into a thin film on a glass substrate having a compressive stress layer, and then at room temperature. Or the method of making it harden | cure by heating the whole glass substrate is mentioned.

The solvent mixed with the coating composition containing the metal oxide fine particles and the binder is preferably an alcohol solvent.
The alcohol solvent has a function of controlling the hydrolysis rate in the coating composition and improving the stability of the coating composition in addition to the function as a solvent.
Examples of alcohol solvents include, but are not limited to, monoalcohols such as methanol, ethanol, n-propanol, and i-propanol; diglycols such as ethyl cellosolve, butyl cellosolve, propyl cellosolve, and ethyl carbitol. Monoethers; and glycols such as ethylene glycol and propylene glycol. Among these, monoalcohols are preferable because the effect of improving the stability of the coating composition is high.
Examples of solvents other than alcohols include, but are not limited to, ketone solvents such as acetone, ester solvents such as ethyl acetate, ether solvents such as tetrahydrofuran, propylene glycol monoethyl ether acetate, and the like. Examples include ether ester solvents.
These solvents may be used alone or as a mixture of two or more.
The amount of the solvent varies depending on the coating method, the type of solvent, the amount of water, and the like, but it is preferably 0.1 parts by mass or more with respect to 1 part by mass of the metal oxide fine particles because the stability of the coating composition is improved. 0.5 parts by mass or more and 800 parts by mass or less are more preferable. It is more preferable that the content is 1 part by mass or more and 200 parts by mass or less because the stability of the coating composition is improved and the film thickness can be controlled with little variation.

The water mixed in the coating composition containing the metal oxide fine particles and the binder has not only a function as a solvent but also a function of promoting hydrolysis in the coating composition and after film formation, thereby preventing reflection. It works to improve the mechanical strength of the layer.
The amount of water varies depending on the coating method, the amount of solvent, etc., but from the viewpoint of improving the mechanical strength of the antireflection layer, it is 0.1 parts by mass or more with respect to 1 part by mass of the metal oxide fine particles. preferable. 0.5 mass parts or more and 800 mass parts or less are more preferable, and 1 mass part or more and 200 mass parts or less are further more preferable.

The catalyst mixed in the coating composition containing the metal oxide fine particles and the binder has a function of promoting the hydrolysis reaction of the hydrolyzable group contained in the binder and the like, and the metal produced by hydrolysis. It has a function of promoting a condensation reaction between a hydroxide and a hydrolyzable group.
In particular, an acid catalyst is preferable from the viewpoint of improving the balance between the stability of the coating composition and the mechanical strength of the antireflection layer after film formation because it promotes the hydrolysis reaction. As the acid catalyst, mineral acids such as hydrochloric acid and nitric acid or acetic acid is more preferable.
Since the basic catalyst further accelerates the condensation reaction, it may impair the stability of the coating composition. When using a basic catalyst, it is preferable that the environment for heating the glass substrate is, for example, a basic catalyst environment such as ammonia.
The compounding amount of the catalyst mixed in the coating composition containing the metal oxide fine particles and the binder is preferably 0.01 parts by mass or more with respect to 100 parts by mass of the metal oxide fine particles. 0.05 parts by mass or more and 200 parts by mass or less is more preferable because the balance between the stability of the coating composition and the mechanical strength of the antireflection layer after film formation is good.

A method for forming a coating composition containing metal oxide fine particles and a binder on a glass substrate having a compressive stress layer is not limited to the following. For example, a spin coater or a roll coater , A method using a coater such as a spray coater, a slit coater or a curtain flow coater, a method such as a dip coating method, or various printing methods such as flexographic printing, screen printing, gravure printing or curved surface printing.
Depending on the surface state of the glass substrate having the compressive stress layer, the coating liquid of the coating composition may be unfamiliar and may repel or have a non-uniform film thickness. In such a case, it is preferable to previously wash or modify the coated surface. Cleaning and modification methods include degreasing cleaning with alcohols such as ethanol or isopropanol, organic solvents such as acetone or hexane, cleaning with alkali or acid, surface polishing with an abrasive, ultrasonic cleaning, ultraviolet irradiation treatment, ultraviolet irradiation Examples of the method include ozone treatment and plasma treatment.

After forming the coating liquid containing the coating composition containing the metal oxide fine particles and the binder as described above, the solution is allowed to stand at room temperature, and the solvent is removed by heating the glass substrate as necessary. Scatter and cure the coating composition.
When the solvent or the like is scattered, voids are formed between particles such as metal oxide fine particles, and the antireflection layer becomes porous. On the other hand, the binder causes a condensation reaction with particles such as metal oxide fine particles, with each other, or with the compressive stress layer to form a strong crosslink. In addition, the hydrolyzable groups of the metal oxide fine particles and the polymer emulsion particles may be hydrolyzed in the same manner as the hydrolyzable groups in the binder, and may undergo a condensation reaction between the particles or the compressive stress layer.

When the solvent of the coating solution containing the coating composition is scattered and the coating composition is cured at room temperature, it can be left for 10 minutes to 10 days at room temperature to improve productivity and the antireflection layer. It is preferable because it can achieve both suppression of damage. The standing time is more preferably 1 hour or more and 4 days or less, and further preferably 4 hours or more and 2 days or less. The room temperature is not particularly limited, but is usually 0 ° C. or higher and 40 ° C. or lower.
When the dispersion of the solvent of the coating solution containing the coating composition and the curing of the coating composition are performed by heating the entire glass substrate, the heating temperature is preferably 400 ° C. or lower in order to suppress the relaxation of the stress of the compressive stress layer. 40 ° C. or more and 200 ° C. or less is more preferable from the viewpoint of productivity and energy reduction, and 50 ° C. or more and 100 ° C. or less is more preferable from the viewpoint that the high surface property of the antireflection layer can be expressed. The heating time is preferably 10 seconds or more and 2 hours or less because both productivity and mechanical strength can be achieved.

The antireflection layer constituting the tempered glass substrate of the present embodiment has a thickness of 0.05 μm or more and 1 μm or less.
By setting the thickness of the antireflection layer within the above range, problems such as generation of cracks hardly occur even under severe use environments, and an excellent antireflection effect can be exhibited over a long period of time. The thickness of the antireflection layer is preferably from 0.07 μm to 0.7 μm, more preferably from 0.08 μm to 0.5 μm.

The ratio of the thickness of the antireflection layer to the thickness of the compressive stress layer (thickness of the antireflection layer / thickness of the compressive stress layer) constituting the tempered glass substrate of this embodiment is 0.001 or more and 0.1 or less. .
Since the tempered glass substrate of the present embodiment is a thin film, it has a strong strength, while vibrations with a frequency different from that of a thick glass substrate occur due to an external pressure such as wind pressure in a use environment. By setting the ratio of the thickness of the antireflection layer to the thickness of the compressive stress layer in the above range, an increase in haze value that is thought to be caused by microcracks of the antireflection layer caused by vibration due to the external pressure is suppressed, and the antireflection layer This function can be expressed over a long period of time. The ratio of the thickness of the antireflection layer to the thickness of the compressive stress layer is preferably 0.0012 times or more and 0.02 times or less, and more preferably 0.0015 times or more and 0.01 times or less.
Although it is not clear what principle the ratio between the thickness of the compressive stress layer and the antireflection layer affects the occurrence of microcracks, the residual strain on the surface of the compressive stress layer is inversely related to the thickness of the compressive stress layer. It is assumed that the occurrence of microcracks correlates with the residual strain on the surface of the compressive stress layer and the thickness of the antireflection layer.

  The refractive index of the antireflection layer is preferably from 1.25 to 1.45 from the viewpoint that both the mechanical strength of the antireflection layer and the substantial antireflection function can be achieved. More preferably, it is 1.28 or more and 1.42 or less, More preferably, it is 1.3 or more and 1.4 or less.

The difference between the refractive index of the antireflection layer and the refractive index of the compressive stress layer (refractive index of the compressive stress layer−refractive index of the antireflection layer) is preferably 0.05 or more and 0.4 or less.
By setting the difference between the refractive index of the antireflection layer and the refractive index of the compressive stress layer within the above range, when subjected to a stress of temperature change under severe use environment, it is between the compressive stress layer and the antireflection layer. This is preferable because distortion can be suppressed to a small level, an increase in haze value that is considered to be caused by microcracks in the antireflection layer can be suppressed, and a substantial antireflection function can be exhibited over a long period of time. More preferably, it is 0.07 or more and 0.35 or less, More preferably, it is 0.05 or more and 0.3 or less.
In addition, the refractive index of an antireflection layer and a compressive-stress layer shall be a value measured by Otsuka Electronics FE-3000 with a measurement wavelength of 633 nm.

The surface of the antireflection layer is preferably hydrophilic from the viewpoint of antifouling properties.
Specifically, the contact angle of water (23 ° C.) is preferably 60 ° or less, more preferably 30 ° or less, and still more preferably 20 ° or less.

[Solar cell module]
The tempered glass substrate of this embodiment is used as a cover glass for solar cell modules.
The solar cell is not particularly limited, and a crystalline semiconductor solar cell, an amorphous silicon solar cell, a compound semiconductor solar cell such as a cadmium-tellurium solar cell or a CIGS solar cell, or an organic thin film solar cell is applicable. it can.
The solar cell module is a matrix solar cell in which solar cells (cells) are connected by wiring, and the upper and lower sides thereof are sandwiched between transparent resins such as ethylene vinyl acetate resin, and further above and below the tempered glass of this embodiment. It is preferable that the substrate is covered (a reflection preventing layer is formed at least on the light receiving surface side).
Alternatively, for example, a back sheet formed of a polyethylene terephthalate layer and an inorganic barrier layer can be used instead of the tempered glass substrate on the lower side (opposite to the light receiving surface).
Alternatively, like a compound semiconductor solar cell, a solar cell (photoelectric conversion layer) is formed on a glass substrate by a vapor deposition method, and a transparent resin such as an ethylene-vinyl acetate copolymer is further formed thereon. It can also be set as the structure covered with the tempered glass substrate of this embodiment.
Alternatively, like an amorphous silicon solar cell, a transparent conductive film is formed on the side opposite to the light receiving surface of the tempered glass substrate of this embodiment by chemical vapor deposition or the like, and a solar cell (photoelectric conversion layer) is formed thereunder Is formed by a vapor deposition method or the like, a transparent resin such as an ethylene-vinyl acetate copolymer is provided below it, and a reinforced glass substrate of this embodiment (or a back sheet formed from a polyethylene terephthalate layer and an aluminum layer is provided below the transparent resin. Etc.).
The solar cell module having such a configuration is light in weight, hardly deteriorates in light transmittance, has excellent antireflection characteristics, and can exhibit high efficiency as a solar cell module over a long period of time.

  Hereinafter, although a specific Example and a comparative example are given and demonstrated, this embodiment is not limited only to these Examples.

Measurement methods for various physical properties and dimensions in the following production examples, examples and comparative examples are shown below.
((1) Compressive stress / thickness of compressive stress layer)
The compressive stress and thickness of the compressive stress layer were calculated from the number of interference fringes observed using a surface stress meter FSM-6000LE (manufactured by Orihara Seisakusho) and the distance between the interference fringes.
In the calculation, the refractive index of the sample was 1.53, and the optical male constant was 28 nm / cm / MPa.

((2) Inner layer tensile stress)
It computed using the following formula from the compressive stress and thickness of the compressive-stress layer calculated | required by said (1).
Inner layer tensile stress = (compression stress of compressive stress layer × thickness of compressive stress layer) ÷ (plate thickness of glass substrate−thickness of compressive stress layer × 2)

((3) Particle diameter of metal oxide fine particles or polymer emulsion particles)
A transmission microscope photograph was taken by adjusting the magnification to 50,000 to 100,000 times with a transmission microscope and adjusting 100 to 200 metal oxide fine particles or polymer emulsion particles.
Subsequently, the particle diameter (average value of the major axis and the minor axis) of each photographed particle was measured, and the average value was obtained and used as the particle diameter.

((4) reflectance, refractive index, film thickness)
The refractive index and film thickness were measured at a wavelength of 633 nm using a reflective spectral film thickness meter FE-3000 (manufactured by Otsuka Electronics Co., Ltd.). Moreover, the reflectance in the wavelength range of 450 to 650 nm was measured, and the average value was taken as the reflectance.

((5) Haze)
It measured by the method prescribed | regulated to JIS-K7361-1 using Nippon Denshoku Industries Co., Ltd. turbidimeter NDH2000.

((6) Total light transmittance)
Using a turbidimeter (Nippon Denshoku Industries NDH2000), the total light transmittance was measured according to JIS-K7105.

((7) Pencil hardness)
Using a test pencil specified by JIS-S6006, the pencil hardness at 1 kg load was evaluated according to the method specified in JIS-K5400.

((8) Water contact angle)
A drop of deionized water (1.0 μL) was placed on the surface of the test object and allowed to stand at 23 ° C. for 10 seconds, and then the water contact angle was measured using a CA-X150 contact angle meter manufactured by Kyowa Interface Science.

((9) Withstand load)
A 5cm square tempered glass substrate is placed on a base with a 4cm square hole and the center of the hole is aligned with the center of the tempered glass substrate, and the center of the tempered glass substrate is weighted with 10N using a cylinder with a diameter of 1cm, It was tested whether the tempered glass substrate was broken.
When 5 sheets were tested and 1 sheet was not broken, the evaluation was ○, when 1 to 2 sheets were broken, Δ, and when 3 sheets or more were broken, the evaluation was x.

(9) Environmental Exposure Test An exposure test (condition: black panel temperature 63 ° C., 18 minutes every 2 hours of rainfall) was conducted for 4000 hours using a sunshine weather meter (manufactured by Suga Test Instruments).

The manufacturing method of the glass substrate used in a following example and a comparative example is shown below.
[Production Examples 1 to 11]
The raw material batch was prepared so as to have the glass composition shown in Table 1 below.
The raw materials used were those used for normal glass production.
The prepared raw material batch was melted and clarified in a platinum crucible. Specifically, the crucible containing the raw material was put into a resistance heating electric furnace heated to 1600 ° C., melted for 4 hours, defoamed and homogenized. Then, after pouring into a mold material, it was gradually cooled from 700 ° C. to obtain a glass block. The glass block was cut and polished so as to have a predetermined thickness shown in Table 2 below at a 50 mm square, and a mirror surface was processed to obtain a glass substrate.
Next, each of the obtained glass substrates was immersed in KNO ₃ molten salt under the temperature and time conditions shown in Table 2 below, dried after washing with pure water, and a tempered glass substrate having a compressive stress layer on the surface layer was obtained.
Table 2 shows the properties of the obtained tempered glass substrate.

A method for synthesizing the polymer emulsion particles used in the following Examples and Comparative Examples is shown below.
[Production Example 12]
Into a reactor having a reflux condenser, a dropping tank, a thermometer and a stirring device, 1600 g of ion-exchanged water and 7 g of dodecylbenzenesulfonic acid were added, and then the temperature was heated to 80 ° C. with stirring. To this, a mixture of 185 g of dimethyldimethoxysilane and 117 g of phenyltrimethoxysilane was dropped over about 2 hours while maintaining the temperature in the reaction vessel at 80 ° C., and then the temperature in the reaction vessel was 80 ° C. And stirring was continued for about 1 hour.
Next, 150 g of butyl acrylate, 30 g of tetraethoxysilane, 145 g of phenyltrimethoxysilane, 1.3 g of 3-methacryloxypropyltrimethoxysilane, 165 g of diethylacrylamide, 3 g of acrylic acid, a reactive emulsifier (trade name “ADEKA” Rear soap SR-1025 ", manufactured by Asahi Denka Co., Ltd., solid content 25% by weight aqueous solution) 13g, ammonium persulfate 2% by weight aqueous solution 40g, ion-exchanged water 1900g, and the temperature in the reaction vessel to 80 ° C It was dripped simultaneously over about 2 hours in the state kept.
Further, as heat curing, stirring was continued for about 2 hours while the temperature in the reaction vessel was 80 ° C.
Thereafter, the mixture was cooled to room temperature, the solid content was adjusted to 10% by mass with ion-exchanged water, and a polymer emulsion particle aqueous dispersion (LTX1) having a particle size of 70 nm was obtained.

[Example 1]
83 g of 60% by mass ethanol solution, 1 g of 35% by mass hydrochloric acid, 0.8 g of tetraethoxylane oligomer (average chain length = 5) as hydrolyzable metal compound, and water-dispersed colloidal silica as metal oxide fine particles (Product name “Snowtech OS”, manufactured by Nissan Chemical Industries, Ltd., solid content 10 mass%, number average particle diameter 8 nm) 10 g, polymer emulsion particle water produced in the above [Production Example 12] as polymer emulsion particles 5 g of dispersion (LTX1, solid content 10% by mass) was mixed and stirred to obtain a coating composition.
The above coating composition was applied to the upper surface (one side) of the tempered glass A produced in [Production Example 1] using a spin coater so as to have a film thickness of 100 nm, then dried at 70 ° C. for 30 minutes, and reflected. The tempered glass which formed the prevention layer and has an antireflection layer was obtained.
The tempered glass substrate having the obtained antireflection layer was used for evaluation.
The obtained evaluation results are shown in Table 3 below.

[Examples 2 to 14]
According to the composition and film forming conditions shown in Table 3 or 4 below, the other conditions were the same as in Example 1 to obtain a coating composition. On the tempered glass substrate shown in Table 3 or Table 4, Table 3 or With the film thicknesses shown in Table 4, the coating composition was applied and dried in the same manner as in Example 1 to obtain tempered glass having an antireflection layer.
Evaluation was performed in the same manner as in Example 1 using the tempered glass having the obtained antireflection layer.
The obtained evaluation results are shown in Tables 3 and 4.

Example 15
A solar cell module was manufactured using the tempered glass having the antireflection layer manufactured in Example 1.
Specifically, it is 1. with respect to 100 parts by mass of an ethylene-vinyl acetate copolymer polymerized by 72% by mass of ethylene and 28% by mass of vinyl acetate on a tempered glass substrate arranged with the antireflection layer side down. A 600 μm-thick sealing material containing 5 parts by mass of 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane is overlaid, and a 250 μm-thick polycrystalline silicon cell (E-TON) Product: Cut to 3cm x 3cm so that the busbar wiring is in the center, and pull the wiring from the upper and lower busbar wiring) with the back side up, and then the above sealing material, then backsheet (Tedlar (40 [mu] m) / PET (250 [mu] m) / Tedlar (40 [mu] m) manufactured by MAP) and heated in a vacuum at 150 [deg.] C. for 5 minutes using an LM50 type vacuum laminator (NPC), then 15 Lamination was performed at 0 ° C. for 30 minutes at 1 atmosphere to obtain a solar cell module.
It was confirmed that power was generated when sunlight was applied to the obtained solar cell module.

[Comparative Example 1]
Evaluation was conducted in the same manner as in Example 1 using the tempered glass substrate having no antireflection layer obtained in Production Example 1 as it was.
The results obtained are shown in Table 4 below.

[Comparative Examples 2 to 5]
According to the composition and film forming conditions shown in Table 4 below, other conditions were obtained in the same manner as in Example 1 to obtain a coating composition. On the tempered glass substrate shown in Table 4 below, the film thickness shown in Table 4 below was given. The coating composition was applied and dried in the same manner as in No. 1 to obtain a tempered glass having an antireflection layer. Evaluation was performed in the same manner as in Example 1 using the tempered glass having the obtained antireflection layer.
The results obtained are shown in Table 4 below.

The symbols shown in Table 3 are as follows.
OS: “Snow Tech OS”, manufactured by Nissan Chemical Industries, solid content 10% by mass, number average particle diameter 8 nm
TES5: oligomer of tetraethoxysilane (average chain length = 5)
LTX-1: Polymer emulsion particles produced in Production Example 10, solid content 10% by mass, number average particle diameter 70 nm

The symbols shown in Table 4 are as follows.
OS: “Snow Tech OS”, manufactured by Nissan Chemical Industries, adjusted to a solid content of 10% by mass, number average particle size 8 nm
OUP: “Snow Tech OUP”, manufactured by Nissan Chemical Industries, adjusted to a solid content of 10% by mass, number average particle size 12 nm
O40: “Snow Tech O40”, manufactured by Nissan Chemical Industries, adjusted to a solid content of 10% by mass, number average particle size 25 nm
TES: tetraethoxysilane TES5: tetraethoxysilane oligomer (average chain length = 5)
LTX-1: Polymer emulsion particles produced in Production Example 10, solid content 10% by mass, number average particle diameter 70 nm

  In Table 4, “70 → 200” and “0.5 → 0.1” mean that two-stage heating was performed. After heating at 70 ° C. for 0.5 hour, 200 This means that heating was performed at 0 ° C. for 0.1 hour.

  In Examples 1 to 14, a light-weight tempered glass substrate that can effectively suppress a decrease in light transmission due to the occurrence of microcracks, has low haze after exposure to the environment, has excellent antireflection characteristics, and is suitable for solar cell module applications was gotten.

  The tempered glass substrate of the present invention has industrial applicability as a constituent material and building material of a solar cell module.

Claims (6)

An inner layer, and a compressive stress layer formed on both outer sides of the inner layer;
An antireflection layer on the surface of at least one of the compression pressure layers on both outer sides of the inner layer; and
A tempered glass substrate comprising:
The antireflection layer is formed by forming a coating composition containing metal oxide fine particles, a binder, and polymer emulsion particles,
The tempered glass substrate has a thickness of 0.15 mm to 2 mm,
The thickness of the antireflection layer is 0.05 μm or more and 1 μm or less,
The ratio of the thickness of the antireflection layer to the thickness of the compressive stress layer (thickness / thickness compression stress layer of the antireflection layer) state, and are 0.001 to 0.1,
The haze after an environmental exposure test (exposure test using a sunshine weather meter (manufactured by Suga Test Instruments) (condition: black panel temperature 63 ° C., 18 minutes every 2 hours of rainfall) for 4000 hours) is 1.2 or less Tempered glass substrate.   The tempered glass substrate according to claim 1, wherein the compressive stress layer is formed by exchanging alkali metal ions on a glass surface.   The difference between the refractive index of the antireflection layer and the refractive index of the compressive stress layer (refractive index of the compressive stress layer−refractive index of the antireflection layer) is 0.05 or more and 0.4 or less. The tempered glass substrate as described in 1.   The tempered glass substrate according to any one of claims 1 to 3, wherein a refractive index of the antireflection layer is 1.25 or more and 1.45 or less. The compressive stress of the compressive stress layer is 250 MPa or more,
The tempered glass substrate according to any one of claims 1 to 4, wherein a tensile stress of the inner layer is 200 MPa or less. The solar cell module which comprises the tempered glass substrate as described in any one of Claims 1 thru | or 5 .