WO2021020457A1

WO2021020457A1 - Optical layer, solar cell module, outer wall material for construction, and building

Info

Publication number: WO2021020457A1
Application number: PCT/JP2020/029100
Authority: WO
Inventors: 酒井　智弘; 賢枝金; 康夫菅原; 祐小野崎; 雄一 ▲桑▼原
Original assignee: Ａｇｃ株式会社; エージーシーグラスユーロップ
Priority date: 2019-07-31
Filing date: 2020-07-29
Publication date: 2021-02-04
Also published as: JPWO2021020457A1

Abstract

Provided are: an optical layer which has excellent concealing properties of solar battery cells, has a white external appearance, and is capable of forming a solar cell module which has excellent power generation efficiency; a solar cell module; an outer wall material for construction; and a building.　This optical layer is used arranged on a solar battery cell on a surface on which sunlight is incident, wherein the optical layer includes a functional layer comprising zirconia particles in which a portion of the constituent elements may be substituted with an element other than Zr, the zirconia particles having an average primary particle size of 40 to 500 nm, or hollow particles of an inorganic oxide having an average primary particle size of 120 to 30,000 nm and containing Si atoms, the functional layer having a thickness of 1 to 1,000 μm.

Description

Optical layers, solar cell modules, building exterior walls and structures

The present invention relates to an optical layer, a solar cell module, a building exterior wall material, and a building.

Installation of solar cell modules is being considered from the viewpoint of cost reduction in power supply and effective use of energy. In general, the solar cell module secures power generation efficiency by using a member having high sunlight transmission. However, in this case, it is often difficult to visually recognize the solar cell and to harmonize with the surroundings in appearance.
In response to this problem, attempts have been made to improve the design by partially coloring the members of the solar cell module.
In Patent Document 1, in order to impart designability to the solar cell module and maintain this designability for a long period of time, a weather-resistant transparent resin layer and a colored ethylene-vinyl acetate resin are laminated and integrated. The invention relating to the weather resistant toning film is disclosed.

Japanese Unexamined Patent Publication No. 2001-04758

In recent years, a solar cell module is required to be able to express various designs. For example, a solar cell module having an excellent concealing property of a solar cell and having a white appearance is required. As one of the methods for obtaining such a solar cell module, there is a method of installing a member colored with a white pigment (for example, titanium oxide) in the solar cell module. However, depending on the type of the white pigment, there may be problems such as exhibiting a bluish white color or insufficient concealment of the solar cell.
On the other hand, even when a solar cell module having excellent concealing properties of a solar cell and exhibiting an excellent white appearance can be obtained, depending on the type of white pigment, light having a wavelength required for power generation is obtained. May not reach the solar cell, causing problems such as insufficient power generation efficiency of the photovoltaic power generation module.

The present invention has been made in view of the above problems, and is an optical layer, a solar cell module, and a building outer wall material capable of forming a solar cell module having excellent concealment property of a solar cell, exhibiting a white appearance, and excellent power generation efficiency. And the provision of buildings is an issue.

As a result of diligent studies on the above problems, the present inventors have included zirconia particles having a predetermined average primary particle diameter or hollow particles of an inorganic oxide containing Si atoms having a predetermined average primary particle diameter, and have a predetermined thickness. We have found that a desired effect can be obtained by using an optical layer having the above functional layer, and have reached the present invention.

That is, the present inventors have found that the above problems can be solved by the following configuration.
[1] An optical layer used by being arranged on the incident surface side of sunlight with respect to a solar cell.
The optical layer has an average primary particle size of 40 to 500 nm, zirconia particles in which some of the constituent elements may be substituted with elements other than Zr, or an average primary particle size of 120 to 30,000 nm. Has a functional layer containing hollow particles of an inorganic oxide containing Si atoms,
[2] The optical layer according to [1], wherein the cumulative 50% diameter of the zirconia particles based on the volume is 0.1 to 5 μm.
[3] The optical layer according to [1] or [2], wherein the specific surface area of the zirconia particles is 0.5 to 100 m ² / g.
[4] The optical layer according to any one of [1] to [3], wherein the content of the zirconia particles is 1 to 80% by mass with respect to the total mass of the functional layer.
[5] The optical layer according to any one of [1] to [4], wherein some of the constituent elements in the zirconia are substituted with Y.
[6] The item according to any one of [1] to [5], wherein the hollow particles are at least one of hollow particles whose shell layer is made of silica and hollow particles whose shell layer is made of glass. Optical layer.
[7] The optical layer according to [1], wherein the volume-based cumulative 50% diameter of the hollow particles is 0.2 to 100 μm.
[8] The optical layer according to [1] or [7], wherein the specific surface area of the hollow particles is 0.1 to 1,000 m ² / g.
[9] The item according to any one of [1], [7] and [8], wherein the content of the hollow particles is 0.1 to 30% by mass with respect to the total mass of the functional layer. Optical layer.
[10] Any of [1] and [7] to [9], wherein the ratio of the average thickness of the shell layer of the hollow particles to the average primary particle diameter of the hollow particles is 0.01 to 0.3. The optical layer according to item 1.
[11] Any of [1] to [10], wherein the optical layer further has a base material made of a glass plate, and the base material is arranged on the incident surface side of sunlight with respect to the functional layer. The optical layer according to item 1.
[12] The optical layer according to any one of [1] to [11], wherein the functional layer further contains a fluororesin.
[13] A solar cell and an optical layer according to any one of [1] to [12] are provided, and the optical layer is located on the incident surface side of sunlight with respect to the solar cell. The solar cell module that is placed.
[14] The solar cell module further has a back surface protective layer arranged on the side opposite to the incident surface side of sunlight in the solar cell.
The solar cell module according to [13], wherein the back surface protective layer is black.
[15] A building exterior wall material having the solar cell module according to [13] or [14].
[16] A building having the building exterior wall material according to [15].

According to the present invention, there are provided an optical layer, a solar cell module, a building exterior wall material, and a building capable of forming a solar cell module having excellent concealment of a solar cell, exhibiting a white appearance, and excellent power generation efficiency. it can.

It is the schematic sectional drawing which shows an example of the optical layer of this invention. It is the schematic sectional drawing which shows one aspect of the solar cell module of this invention. It is a graph which shows the solar spectrum on the ground, and the spectral sensitivity curve of the solar cell of single crystal silicon. It is the schematic sectional drawing which shows one aspect of the solar cell module of this invention. It is the schematic sectional drawing which shows one aspect of the solar cell module of this invention. It is a schematic plan view which shows an example of the solar cell array constructed by the solar cell module of this invention.

The meanings of the terms in the present invention are as follows.
The primary particles of zirconia particles and hollow particles are particles observed using a scanning electron microscope.
The average primary particle size of the zirconia particles and hollow particles is obtained by taking an SEM photograph of the particles using a scanning electron microscope, measuring 100 major axis diameters of the primary particles in the image, and performing an arithmetic average. Value. In the examples, S-4800 (manufactured by Hitachi High-Technologies Corporation) was used as the scanning electron microscope. The major axis diameter of the primary particles in the image means the longest line segment of the primary particles in the image when a straight line is drawn from one end to the other.
The cumulative 50% diameter of the zirconia particles and the hollow particles based on the volume is obtained by performing ultrasonic treatment on the zirconia particles or the dispersion containing the hollow particles and then measuring using a particle size distribution measuring device. Cumulative 50% diameter (D50), and detailed measurement conditions are as described in Examples. In the examples, MT3300EXII (manufactured by Microtrac Bell) was used as the particle size distribution measuring device.
The specific surface area of the zirconia particles and the hollow particles is a value obtained by the nitrogen adsorption BET method under degassing conditions at 200 ° C. for 20 minutes using a specific surface area measuring device. In the examples, HM model-1208 (manufactured by Mountech) was used as the specific surface area measuring device.
The density of zirconia particles and hollow particles is a value obtained by measuring with a pycnometer. In the examples, ULTRAPYC 1200e (manufactured by Kantachrome) was used.

The thickness of each layer of the optical layer can be obtained by appropriately using a thickness meter, an eddy current film thickness meter, or the like. In the present invention, the thickness of the functional layer is obtained by using an eddy current type film thickness meter (trade name "EDY-5000", manufactured by Sanko Denshi Co., Ltd.).
The visible light average transmittance, visible light average scattering transmittance, near-infrared light average transmittance, and near-infrared light average diffusion transmittance of the optical layer are optical so that light is incident from the normal direction of the surface of the optical layer. It is calculated based on the value measured using a spectrophotometer with a layer installed, and the detailed measurement conditions are as described in the examples. In the examples, V-670 (manufactured by JASCO Corporation) was used.
The L ^* , a ^* , b ^* and stimulus purity of the optical layer are values obtained by measuring with a spectrocolorimeter. In the examples, SD6000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.) was used.

(Meta) acrylate is a general term for acrylate and methacrylate, and (meth) acrylic is a general term for acrylic and methacrylic.
The hydrolyzable silyl group is a group that becomes a silanol group by hydrolysis.
The acid value and the hydroxyl value are values measured according to the description of JIS K 0070-3 (1992), respectively.
The mass of the solid content of the composition or the like is the mass obtained by removing the solvent from the composition when the composition contains a solvent. The mass of the solid content of the composition is determined as the mass remaining after heating 1 g of the composition at 140 ° C. for 20 minutes.

The optical layer of the present invention is an optical layer used by being arranged on the incident surface side of sunlight with respect to a solar cell, and the optical layer is one of the constituent elements having an average primary particle diameter of 40 to 500 nm. It has a functional layer containing zirconia particles whose portions may be substituted with elements other than Zr, or hollow particles of an inorganic oxide containing Si atoms having an average primary particle diameter of 120 to 30,000 nm. The thickness of the functional layer is 1 to 1,000 μm.
In the present specification, "the zirconia particles having an average primary particle diameter of 40 to 500 nm and in which some of the constituent elements may be replaced with elements other than Zr" are also referred to as "specific zirconia particles". Further, "hollow particles of an inorganic oxide containing a Si atom having an average primary particle diameter of 120 to 30,000 nm" are also referred to as "specific hollow particles". In addition, the specific zirconia particles and the specific hollow particles are collectively referred to as "specific particles".

By using the optical layer of the present invention, it is possible to form a solar cell module which is excellent in concealment of a solar cell, has a white appearance, and is excellent in power generation efficiency. This is presumed to be due to the following reasons.
When the reflectance of the optical layer is measured, if the reflectance in the visible light region having a wavelength of 400 to 780 nm is constant, it can be said that the optical layer exhibits an excellent white appearance. Here, when the present inventors evaluated a functional layer formed by using nanoparticles of titanium oxide often used as a white pigment, the reflectance near a wavelength of 400 nm became high (specifically, the wavelength). (A peak reflectance is observed near 400 nm), and it was found that the appearance of the optical layer is bluish white.
In response to this problem, when a functional layer was formed using specific zirconia particles or specific hollow particles, it was found that the appearance of the optical layer including the functional layer was excellent white. It is presumed that the reason for this is that the reflectance in the visible light region having a wavelength of 400 to 780 nm is constant as compared with the case where the nanoparticles of titanium oxide are used.
Further, by using the specific zirconia particles or the specific hollow particles whose average primary particle diameter is within the predetermined value range, and when the thickness of the functional layer is within the predetermined range, the excellent concealment property of the solar cell and the excellent concealment property of the solar cell are obtained. It is presumed that the excellent power generation efficiency of the solar cell module was compatible with each other.

FIG. 1 is a schematic cross-sectional view showing an example of the optical layer of the present invention. As shown in FIG. 1, the optical layer 10 has a base material 110 and a functional layer 120.

Hereinafter, the optical layer of the present invention will be described for each embodiment. The first embodiment is an embodiment in which the functional layer contains specific zirconia particles, and the second embodiment is an embodiment in which the functional layer contains specific hollow particles.
The optical layer of the present invention may include both specific zirconia particles and specific hollow particles.

<First Embodiment>
The optical layer of the first embodiment is an optical layer used by being arranged on the incident surface side of sunlight with respect to the solar cell, has a functional layer containing specific zirconia particles, and has a thickness of the functional layer. Is 1 to 1,000 μm. In the present specification, the optical layer of the first embodiment is also referred to as "optical layer A".

The optical layer A is arranged and used on the incident surface side of sunlight with respect to the solar cell. Usually, the solar cells are not used alone, but a plurality of solar cells are arranged so as to be adjacent to each other, and each is electrically connected in series or in parallel. Therefore, typically, the optical layer A is arranged as a continuous surface with respect to these plurality of solar cells, and is present on the incident surface side of sunlight with respect to the solar cells.

The optical layer A typically does not include a sealing layer that seals the solar cell. The optical layer A is preferably laminated on the sealing layer (on the side irradiated with sunlight rather than the sealing layer) from the viewpoint of being superior to the effect of the present invention.

The optical layer A may have irregularities on the surface on the air side to the extent that the effects of the present invention are not impaired. Examples of the mode in which the optical layer A has irregularities on the surface on the air side include a mode in which the optical layer A has a functional layer as the outermost layer on the air side and the functional layer contains a matting agent, and an optical layer A. There is an embodiment in which the base material (described later) is provided as the outermost layer on the air side, and the base material is appropriately surface-treated by polishing or the like.

The thickness of the optical layer A is preferably 0.7 to 9.7 mm, more preferably 1 to 8 mm, and particularly preferably 2 to 6 mm from the viewpoint of ease of handling of the solar cell module.

In the optical layer A, the L ^* value, a ^* value, and b ^* value in the L ^* a ^* b ^* color system are 30 to 100, -10 to 10, and -15 to 10 in this order. It is preferably 50 to 100, -3 to 3, and -10 to 5 in particular. When the L ^* value, a ^* value, and b ^* value of the optical layer A are a combination of the above ranges, the optical layer A becomes close to achromatic color, and thus exhibits a more excellent white color.
The optical layer A preferably has a stimulus purity of 0 to 20, more preferably 0 to 15, and particularly preferably 0 to 12 in the XYZ color system. When the stimulation purity of the optical layer A is within the above range, the optical layer A exhibits a more excellent white color.
In the optical layer A, when the L ^* value, the a ^* value, and the b ^* value are a combination of the above ranges and the stimulation purity is in the above range, the optical layer A exhibits a particularly excellent white color.

The visible light average transmittance (V1) of the optical layer A is preferably 90% or less, more preferably 85% or less, and particularly preferably 80% or less from the viewpoint of hiding property of the solar cell.
The V1 of the optical layer A is preferably 5% or more, more preferably 15% or more, and particularly preferably 24% or more from the viewpoint of power generation efficiency of the solar cell module.
Here, the visible light average transmittance (V1) means a value obtained by arithmetically averaging the total light transmittance in increments of 5 nm in the visible light region having a wavelength of 400 to 780 nm.
The visible light average scattering transmittance (V2) of the optical layer A is preferably 5% or more, more preferably 10% or more, and more preferably 24% or more from the viewpoint of power generation efficiency of the solar cell module and whiteness of the optical layer A. Is particularly preferable. The upper limit of V2 is usually 100%.
Here, the visible light average scattering transmittance (V2) is a value obtained by subtracting the value obtained by subtracting the value obtained by arithmetically averaging the linear transmittance in increments of 5 nm in the visible light region having a wavelength of 400 to 780 nm from the visible light average transmittance (V1). means.
The visible light scattering rate (V3) of the optical layer A is preferably 30% or more, more preferably 45% or more, particularly 60% or more, from the viewpoint of power generation efficiency of the solar cell module and whiteness of the optical layer A. preferable. The upper limit of V3 is usually 100%.
Here, the visible light scattering rate (V3) means a value [(V2 / V1) × 100] calculated by dividing the visible light average scattering transmittance (V2) by the visible light average transmittance (V1). ..

The near-infrared light average transmittance (N1) of the optical layer A is preferably 20% or more, more preferably 30% or more, and particularly preferably 35% or more from the viewpoint of power generation efficiency of the solar cell module. The upper limit of N1 is usually 100%.
Here, the near-infrared light average transmittance (N1) means a value obtained by arithmetically averaging the total light transmittance in increments of 5 nm in the near-infrared light region having a wavelength of 780 to 1,200 nm.
The near-infrared light average scattering transmittance (N2) of the optical layer A is preferably 10% or more, more preferably 24% or more, and particularly preferably 35% or more from the viewpoint of power generation efficiency of the solar cell module. The upper limit of N2 is usually 100%.
Here, the near-infrared light average scattered transmittance (N2) is calculated from the near-infrared light average transmittance (N1) in a near-infrared light region having a wavelength of 780 to 1,200 nm in increments of 5 nm. It means the value obtained by subtracting the average value.
The near-infrared light scattering rate (N3) of the optical layer A is preferably 10% or more, more preferably 20% or more, and particularly preferably 45% or more from the viewpoint of power generation efficiency of the solar cell module. The upper limit of N3 is usually 100%.
Here, the near-infrared light scattering rate (N3) is a value calculated by dividing the near-infrared light average scattering transmittance (N2) by the near-infrared light average transmittance (N1) [(N2 / N1). × 100].

The values of V1 to V3 and N1 to N3 in the optical layer A can be adjusted by, for example, the particle size or the amount of the specific zirconia particles added, or the thickness of the optical layer A.

The thickness of the functional layer of the optical layer A is 1 to 1,000 μm, preferably 5 to 200 μm, more preferably 10 to 100 μm, and particularly preferably 20 to 60 μm.
When the thickness of the functional layer is 1,000 μm or less, the power generation efficiency of the solar cell module is excellent and the cost is low. When the thickness of the functional layer is 1 μm or more, the concealing property of the solar cell is excellent.
The thickness of the functional layer is obtained by arithmetically averaging a value obtained by subtracting the thickness of the base material from the total thickness of the functional layer and the base material measured by a micrometer at any 10 points.

The refractive index of the functional layer of the optical layer A is 1.4 to 2.6 because the difference in refractive index from the sealing layer becomes small, the total light transmittance increases, and the power generation efficiency of the solar cell module tends to increase. Is preferable, and 1.4 to 2.0 is particularly preferable.
The refractive index of the functional layer is a value measured by a commercially available refractive index measuring device, an ellipsometer, or the like.

The functional layer included in the optical layer A contains specific zirconia particles.
The shape of the specific zirconia particles is any of spherical, elliptical, needle-shaped, plate-shaped, rod-shaped, cone-shaped, columnar, cubic, rectangular parallelepiped, diamond-shaped, star-shaped, scaly, amorphous, etc. However, a spherical shape is preferable in terms of dispersibility.
The specific zirconia particles are solid particles.

The average primary particle diameter of the specific zirconia particles is 40 to 500 nm, preferably 45 to 400 nm, more preferably 50 to 300 nm, and particularly preferably 55 to 200 nm. When the average primary particle size is 40 nm or more, the concealing property of the solar cell is more excellent. When the average primary particle size is 500 nm or less, it is possible to satisfy at least one of the fact that the optical layer A exhibiting a more excellent white appearance can be obtained and that the solar cell module having more excellent power generation efficiency can be obtained. ..

The cumulative 50% diameter of the specific zirconia particles based on the volume is preferably 0.1 to 5.0 μm, more preferably 0.1 to 2.0 μm, and particularly preferably 0.1 to 1.0 μm. When the cumulative 50% diameter is 0.1 μm or more, the concealing property of the solar cell is more excellent. When the cumulative 50% diameter is 6.0 μm or less, at least one of the fact that the optical layer A exhibiting a more excellent white appearance can be obtained and that the solar cell module having more excellent power generation efficiency can be obtained is satisfied. Can be done.

The specific surface area of specific zirconia particles is preferably 0.5 ~ 100m ² / g, more preferably from 1 ~ ^50m 2 / g, particularly preferably 3 ~ ^30m 2 / g. Within the above range, scattering of near-infrared light by the specific zirconia particles is preferable, and the power generation efficiency of the solar cell module is more excellent.

Density of specific zirconia particles, in terms of dispersibility, preferably 4.5 ~ 7.0g / cm ^3, particularly preferably 5.0 ~ 6.5g / cm ^3.
The refractive index of the specific zirconia particles is preferably 1.9 to 2.3, particularly preferably 2.0 to 2.2.
The refractive index of the specific zirconia particles means the refractive index of the material constituting the specific zirconia particles (for example, when the material is obtained by pulverization or the like, the material before pulverization), and is usually a literature value of the above-mentioned material. Alternatively, the refractive index of the powder can be directly measured by the JIS K 7142: 2014 B method.

The zirconia (zirconium oxide) constituting the specific zirconia particles may have at least a part of the constituent elements substituted with an element other than Zr (hereinafter, also referred to as a specific element), or may not be substituted with the specific element. However, it is preferably substituted with a specific element in that the crystal phase transition can be suppressed and the effect of using the specific zirconia particles is more exerted.
Examples of the specific element as the substitution element include Y, Al, and Ce, and Y is preferable in that the crystal phase transition can be further suppressed and the effect of using the specific zirconia particles is more exhibited.
The content of the specific element is preferably 1 to 30 mol% with respect to Zr in the specific zirconia particles in that the crystal phase transition can be suppressed and the effect of using the specific zirconia particles is more exerted. -8 mol% is particularly preferred.

As the specific zirconia particles, a commercially available product may be used, and examples of the commercially available product include the "TZ" series (manufactured by Tosoh Corporation).

The content of the specific zirconia particles is preferably 1 to 80% by mass, more preferably 5 to 65% by mass, and particularly preferably 10 to 50% by mass with respect to the total mass of the functional layer. When it is 1% by mass or more, the concealing property of the solar cell is more excellent. If it is 80% by mass or less, a solar cell module excellent in power generation efficiency can be obtained.

The functional layer included in the optical layer A may include a matrix. The matrix plays a role of fixing the specific particles contained in the functional layer in a dispersed state.
Specific examples of the matrix include resin, glass obtained by sintering a glass frit composition, silica, and the like. The matrix may be composed of two or more of the above components. Of these, resin is preferable as the matrix.

Examples of the glass obtained by sintering the glass frit composition and the silica include the glass obtained by sintering the glass frit composition described in International Publication No. 2019/116859 and silica.

When the matrix contains a resin, the resin consists of a cured product of a thermoplastic resin or a curable resin. Crosslinked products of polymers having a crosslinkable group, polycondensated polymers of compounds having a polypolymerizable group, addition polymers of compounds having an addition polymerizable group, etc. are also included in the category of cured products of thermoplastic resins and curable resins. It shall be. Further, the thermoplastic resin having a reactive group such as a hydroxy group may form a matrix without the reactive group reacting.

When the matrix contains a resin, specific examples of the resin include alkyd resin, aminoalkyd resin, polyester resin, epoxy resin, urethane resin, epoxy-polyester resin, vinyl acetate resin, acrylic resin, vinyl chloride resin, phenol resin, and modification. Examples thereof include polyester resin, fluororesin, acrylic silicone resin, silicone resin, ethylene-vinyl acetate resin, and polyvinyl butyral resin. Of these, as for the resin that becomes a matrix by curing or cross-linking, the cured product or the cross-linked product becomes a matrix. As the resin contained in the matrix, a fluororesin composed of a fluoropolymer or a crosslinked product of a crosslinkable fluoropolymer is preferable from the viewpoint of weather resistance.
The matrix may contain two or more of the resins.

The fluorine-containing polymer preferably contains a unit based on a fluoroolefin (hereinafter, also referred to as a unit F).
The unit is a general term for an atomic group based on one molecule of the monomer, which is directly formed by polymerizing a monomer, and an atomic group obtained by chemically converting a part of the atomic group. The content (mol%) of each unit with respect to all the units contained in the polymer is determined by analyzing the polymer by a nuclear magnetic resonance spectrum (NMR) method.

A fluoroolefin is an olefin in which one or more H atoms are substituted with F atoms. In the fluoroolefin, one or more H atoms which are not substituted with F atoms may be substituted with chlorine atoms.
Specific examples of fluoroolefins include CF ₂ = CF ₂ , CF ₂ = CFCl, CF ₂ = CHF, CH ₂ = CF ₂ , CF ₂ = CFCF ₃ , CF ₂ = CHCF ₃ , CF ₃ CH = CHF, CF ₃ CF = CH ₂ , CH ₂ = CX ⁰ (CF ₂ ) _n0 Y ⁰ (in the formula, X ⁰ and Y ⁰ are independently H or F atoms, and n0 is an integer of 2 to 10). CF ₂ = CF ₂ , CH ₂ = CF ₂ , CF ₂ = CFCl, CF ₃ CH = CHF, CF ₃ CF = CH ₂ from the viewpoints of the represented monomers and the excellent weather resistance of the functional layer. Preferably, CF ₂ = CFCl is particularly preferred. Two or more kinds of fluoroolefins may be used in combination.

The fluorine-containing polymer may contain only the unit F, may contain a unit based on a monomer containing an F atom other than the unit F and the fluoroolefin, and may contain a unit amount free of the unit F and the F atom. It may include body-based units.

Examples of the fluoropolymer containing only the unit F include a fluoroolefin homopolymer, two or more copolymers of fluoroolefin, and specific examples thereof include polytetrafluoroethylene and polychlorotrifluoroethylene. Examples thereof include tetrafluoroethylene-hexafluoropropylene copolymer and polyvinylidene fluoride.

Examples of the fluorine-containing polymer containing a unit based on a monomer containing an F atom other than the unit F and a fluoroolefin include a fluoroolefin-perfluoro (alkyl vinyl ether) copolymer, and specific examples thereof include tetrafluoroethylene. -Perfluoro (alkyl vinyl ether) copolymers can be mentioned.

The fluorine-containing polymer preferably contains units F and units based on a monomer containing no F atom from the viewpoint of dispersibility of specific particles in the matrix.

Specific examples of the fluoropolymer containing the unit F and a unit based on a monomer containing no F atom include a chlorotrifluoroethylene-vinyl ether copolymer and a chlorotrifluoroethylene-vinyl ether-vinyl ester copolymer. , Chlorotrifluoroethylene-vinyl ester-allyl ether copolymer, tetrafluoroethylene-vinyl ester copolymer, tetrafluoroethylene-vinyl ester-allyl ether copolymer, ethylene-tetrafluoroethylene copolymer. A chlorotrifluoroethylene-vinyl ether copolymer is preferable from the viewpoint of excellent design of the solar cell module.

The content of the unit F is preferably 20 to 100 mol%, more preferably 30 to 70 mol%, and more preferably 40 to 60 mol% with respect to all the units contained in the fluorine-containing polymer from the viewpoint of weather resistance of the functional layer. Is particularly preferable.

From the viewpoint of durability of the functional layer, the fluorine-containing polymer contains a crosslinkable fluorine-containing weight containing a unit having a crosslinkable group (hereinafter, also referred to as unit C) as a unit based on a monomer containing no F atom. It is preferably coalesced. The unit C may be a unit based on a monomer having a crosslinkable group (hereinafter, also referred to as a monomer C), and the crosslinkable group of the fluoropolymer containing the unit C may be a different crosslinkable group. It may be a unit obtained by converting to. Such a unit is obtained by reacting a fluorine-containing polymer containing a unit having a hydroxy group with a polycarboxylic acid, an acid anhydride thereof, or the like to convert a part or all of the hydroxy group into a carboxy group. The unit is mentioned. Specific examples of the crosslinkable group include a hydroxy group, a carboxy group, an amino group, an epoxy group and a hydrolyzable silyl group, and a hydroxy group and a carboxy group are preferable from the viewpoint of the strength of the functional layer.
The crosslinkable group of the unit C may be crosslinked with a curing agent described later in the matrix, may remain without being crosslinked, and is preferably crosslinked with the curing agent. When the crosslinkable group of the unit C is crosslinked by a curing agent, the durability of the functional layer is more excellent. When the crosslinkable group of the unit C remains without crosslinking, the dispersibility of the specific particles in the matrix is more excellent.

Examples of the monomer having a hydroxy group include vinyl ether, vinyl ester, allyl ether, allyl ester, (meth) acrylate, allyl alcohol and the like having a hydroxy group.
Specific examples of the monomer having a hydroxy group include CH ₂ = CHO-CH _2- cycloC ₆ H _10- CH ₂ OH, CH ₂ = CHCH ₂ O-CH _2- cycloC ₆ H _10- CH ₂ OH, CH. _{_{_{_{2 = CHOCH 2 -cycloC 6 H 10}}}} -CH 2 - (OCH 2 CH 2) 15 OH, CH 2 = CHOCH 2 CH 2 OH, CH 2 = CHCH 2 OCH 2 CH 2 OH, CH 2 = CHOCH 2 CH ₂ CH ₂ CH ₂ OH, and _{_{_{_{CH 2 = CHCH 2 OCH 2 CH}}}} 2 CH 2 CH 2 OH and the like, from the viewpoint of copolymerizability with the _{_{_{fluoroolefin, CH 2 = CHCH 2 OCH 2}}} CH 2 OH or CH ₂ = CHOCH ₂ CH ₂ CH ₂ CH ₂ OH is preferable.
In addition, "-cycloC ₆ H _10- " represents a cyclohexylene group, and the binding site of "-cycloC ₆ H _10- " is usually 1,4-.

Examples of the monomer having a carboxy group include unsaturated carboxylic acid, (meth) acrylic acid, and a monomer obtained by reacting a hydroxy group of the above-mentioned monomer having a hydroxy group with a carboxylic acid anhydride. ..
Specific examples of the monomer having a carboxy group include CH ₂ = CHCOOH, CH (CH ₃ ) = CHCOOH, CH ₂ = C (CH ₃ ) COOH, HOOCCH = CHCOOH, CH ₂ = CH (CH ₂ ) _n11 COOH. Monomer represented by (where n11 represents an integer of 1 to 10), CH ₂ = CHO (CH ₂ ) _n12 OC (O) CH ₂ CH ₂ Monomer represented by COOH (however, where n12 represents an integer of 1 to 10), and from the viewpoint of copolymerizability with a fluoroolefin, a monomer represented by CH ₂ = CH (CH ₂ ) _n11 COOH or CH ₂ = CHO (CH). ₂ ) A monomer represented by _n12 OC (O) CH ₂ CH ₂ COOH is preferable.

Two or more types of monomer C may be used in combination.
The content of the unit C is preferably 0.5 to 35 mol%, more preferably 3 to 25 mol%, still more preferably 5 to 25 mol%, and 5 to 20 with respect to all the units contained in the fluorine-containing polymer. Mol% is particularly preferred.

The fluorine-containing polymer may further contain a unit based on a monomer having no crosslinkable group as a unit based on a monomer containing no F atom. As a unit based on a monomer having no crosslinkable group, one or more monomers selected from the group consisting of alkene, vinyl ether, vinyl ester, allyl ether, allyl ester, and (meth) acrylate (hereinafter,). , Also referred to as monomer D) (hereinafter, also referred to as unit D).

Specific examples of the monomer D include ethylene, propylene, 1-butene, ethyl vinyl ether, tert-butyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, vinyl acetate, vinyl pivalate, and vinyl neononanonate (manufactured by HEXION). Name "Beova 9" etc.), Vinyl neodecanoate (manufactured by HEXION, trade name "Beova 10" etc.), Vinyl benzoate, tert-butyl Vinyl benzoate, tert-butyl (meth) acrylate, benzyl (meth) acrylate Can be mentioned.
Two or more types of monomer D may be used in combination.
When the fluorine-containing polymer contains the unit D, the content of the unit D is preferably 5 to 60 mol%, particularly preferably 10 to 50 mol%, based on all the units contained in the fluorine-containing polymer.

The fluorine-containing polymer may contain 30 to 70 mol% of the unit F, 0.5 to 35 mol% of the unit C, and 5 to 60 mol% of the unit D with respect to all the units contained in the fluorine-containing polymer. preferable.

As the fluorine-containing polymer, a commercially available product may be used. Specific examples of commercially available products include the "Lumiflon" series (AGC product name), the "Kynar" series (Arkema product name), the "Zeffle" series (Daikin Industries product name), and the "Eterflon" series (Eternal product). Name), "Zendura" series (Honeywell product name).

The fluorine-containing polymer is produced by a known method. Specific examples of the method for producing a fluorine-containing polymer include solution polymerization and emulsion polymerization using a radical initiator and the like. A polymerization stabilizer, a polymerization inhibitor, a surfactant and the like may be used during or after the production of the fluorine-containing polymer.

When the matrix in the present invention contains a fluororesin, the content of the fluororesin in the functional layer is preferably 5 to 95% by mass, preferably 10 to 90% by mass, based on the total mass of the functional layer from the viewpoint of weather resistance of the functional layer. Mass% is particularly preferred.

When the matrix in the present invention contains a fluororesin, the F atom content of the functional layer is preferably 65% by mass or less, more preferably 50% by mass or less, and more preferably 40% by mass, from the viewpoint of dispersibility of specific particles in the matrix. The following is more preferable, 25% by mass or less is particularly preferable, and 20% or less is most preferable. The F atom content of the functional layer is preferably 0.1% by mass or more, more preferably 3% by mass or more, and 5% by mass or more, based on the total mass of the functional layer, from the viewpoint of weather resistance of the functional layer. Is more preferable, and 10% by mass or more is particularly preferable.
In this case, if the F atom content of the functional layer is preferably 0.1 to 25% by mass, particularly preferably 5 to 20% by mass, the specific particles are dispersed particularly well in the functional layer, so that the solar cell module Excellent in design and power generation efficiency.

The F atom content in the functional layer means the content (mass%) of F atoms with respect to all the atoms constituting the functional layer. The F atom content in the functional layer is obtained by measuring with the following conditions by an automatic sample combustion device-ion chromatography method (AQF-IC method).
<Analysis conditions>
-Automatic sample combustion device: Automatic sample combustion device AQF-100 manufactured by Mitsubishi Chemical Analytech Co., Ltd.
Combustion conditions: Solid sample mode Sample amount: 2 to 20 mg
-Ion chromatograph device: Thermo Fisher SCIENTIFIC column: IonpacAG11HC + IonpacAS11HC
Eluent: KOH 10mN (0-9min), 10-16mN (9-11min), 16mN (11-15min), 16-61mN (15-20min), 60mN (20-25min)
Flow velocity: 1.0 mL / min Suppressor: ASRS
Detector: Conductivity detector Injection volume: 5 μL

From the viewpoint of hardness and durability of the functional layer, the matrix preferably contains a resin having a crosslinked structure formed by reacting a crosslinkable group of the crosslinkable resin with a curing agent.
Further, a crosslinked structure may be formed between the resin constituting the matrix and a layer other than the functional layer. In this case, the crosslinkable group of the crosslinkable resin and the reactive group of the layer other than the functional layer may be crosslinked with a curing agent or the like.
As the reactive group possessed by the layer other than the functional layer, the silanol group when the layer other than the functional layer is a base material made of a glass plate, and the layer other than the functional layer are surface-treated with a silane coupling agent or the like. Examples thereof include a hydrolyzable silyl group in the case of a layer.
For example, when a functional layer is formed on a base material made of a glass plate from a resin containing a curing agent having at least one selected from a hydrolyzable silyl group and a silanol group, the hydrolyzable silyl group of the curing agent and the like (Specifically, the silanol group generated by hydrolysis) reacts with the silanol group existing on the surface of the glass plate to form a crosslinked structure. Therefore, the adhesion of the functional layer to the base material is more excellent. Further, in this case, when the base material is a layer made of a glass plate surface-treated with a silane coupling agent or the like, the silanol group existing on the surface of the glass plate and the hydrolyzable silyl of the silane coupling agent The groups and the like react with the hydrolyzable silyl groups and the like of the curing agent to form a crosslinked structure. Therefore, the adhesion between the base material and the functional layer is improved, and the durability of the optical layer A is excellent.

The functional layer of the optical layer A may contain components other than the above. Examples of such a component include additives described later.

As one form of the functional layer in the first embodiment, it is formed by using a composition containing at least a polymer (particularly, a fluorine-containing polymer) and specific zirconia particles (hereinafter, referred to as composition (1)). It is a layer to be. The composition (1) may contain two or more kinds of polymers. Further, the composition (1) may contain two or more kinds of specific zirconia particles.
Examples of the polymer include polymers contained in the resin constituting the above-mentioned matrix, and a fluorine-containing polymer is preferable.

When the composition (1) is a composition containing a fluorine-containing polymer as a polymer (hereinafter referred to as composition (1F)), the fluorine-containing polymer in the composition (1F) has the following physical characteristics. It is preferable to have.
The acid value of the fluorine-containing polymer is preferably 1 to 200 mgKOH / g, more preferably 1 to 150 mgKOH / g, further preferably 3 to 100 mgKOH / g, and particularly preferably 5 to 50 mgKOH / g from the viewpoint of the strength of the functional layer. preferable.
The hydroxyl value of the fluorine-containing polymer is preferably 1 to 200 mgKOH / g, more preferably 1 to 150 mgKOH / g, further preferably 3 to 100 mgKOH / g, and particularly preferably 10 to 60 mgKOH / g from the viewpoint of the strength of the functional layer. preferable.
The fluorine-containing polymer may have either an acid value or a hydroxyl value, or may have both.

The F atom content of the fluorine-containing polymer is preferably 70% by mass or less, more preferably 50% by mass or less, further preferably 30% by mass or less, and 28% by mass or less from the viewpoint of dispersibility of specific particles in the matrix. Is particularly preferable. The F atom content of the fluorine-containing polymer is preferably 10% by mass or more, particularly preferably 15% by mass or more, from the viewpoint of weather resistance of the functional layer.
In particular, when the F atom content of the fluorine-containing polymer is preferably 15 to 30% by mass, particularly preferably 15 to 28% by mass, the specific particles are well dispersed in the functional layer, so that the design of the solar cell module Excellent in properties and power generation efficiency.
The F atom content of the fluorine-containing polymer means the ratio (mass%) of F atoms to all the atoms constituting the fluorine-containing polymer. The F atom content is determined by analyzing the fluorine-containing polymer by a nuclear magnetic resonance spectroscopy (NMR) method.

Other than the above, the details are omitted because they are the same as the fluorine-containing polymer in the above-mentioned matrix.

The content of the fluorine-containing polymer in the composition (1F) is 10 to 90% by mass with respect to the total mass of the composition (1F) from the viewpoint of the dispersibility of specific particles in the composition (1F). It is preferable, and 20 to 40% by mass is particularly preferable.
The content of the fluorine-containing polymer in the solid content of the composition (1F) is 10 with respect to the total solid content mass of the composition (1F) from the viewpoint of the dispersibility of specific particles in the composition (1F). It is preferably from 90% by mass, particularly preferably 40 to 70% by mass.
The content of the specific particles in the solid content of the composition (1F) is 5 to 80 with respect to the total solid content mass of the composition (1F) from the viewpoint of the dispersibility of the specific particles in the composition (1F). It is preferably by mass, particularly preferably 20 to 50% by mass.

The composition (1) may contain components other than the specific zirconia particles and the polymer (hereinafter, also referred to as additives). Examples of such additives include hardeners, catalysts, fillers (organic fillers such as resin beads), light stabilizers, ultraviolet absorbers, matting agents, dispersants, defoamers, leveling agents, degassing agents, and fillings. Examples thereof include agents, heat stabilizers, thickeners, surfactants, antistatic agents, rust preventives, silane coupling agents, antifouling agents, decontamination treatment agents, plasticizers, adhesives and the like.
The composition (1) may contain components not included in the functional layer, if necessary. Specific examples of such components include liquid media. Liquid media such as water and organic solvents are components that are removed by evaporation and removal during matrix formation, and are included in the composition (1) when the functional layer is formed by means such as coating.
The solid content concentration of the composition (1F) is preferably adjusted to 10 to 90% by mass, preferably 40 to 70% by mass, based on the total mass of the composition (1F) by the above liquid medium. It is especially preferable to have.

When the composition (1) contains a curable resin or a crosslinkable polymer, it is particularly preferable to include a curing agent that constitutes a crosslinked structure in the above-mentioned functional layer among the additives.
When the polymer in the composition (1) is a crosslinkable polymer, the functional layer can be cured by crosslinking with a curing agent. In this case, the functional layer has a crosslinked structure of a polymer and a curing agent.
When the curing agent in the composition (1) has one or more selected from a hydrolyzable silyl group and a silanol group, a curing agent, a glass plate containing silicon oxide as a base material, and depending on the case. It is considered that the polymer reacts with each other to form a functional layer having a crosslinked structure of the curing agent, the glass plate, and optionally the polymer.
When the composition (1) contains a curing agent, the content of the curing agent is preferably 5 to 200 parts by mass and particularly 10 to 150 parts by mass with respect to 100 parts by mass of the polymer in the composition (1). preferable.

When the polymer has a hydroxy group, the curing agent is preferably a compound having two or more isocyanate groups or blocked isocyanate groups in one molecule.
When the polymer has a carboxy group, the curing agent is preferably a compound having two or more epoxy groups, carbodiimide groups, oxazoline groups or β-hydroxyalkylamide groups in one molecule.
When the polymer has both a hydroxy group and a carboxy group, a compound having two or more isocyanate groups or blocked isocyanate groups in one molecule and one epoxy group, carbodiimide group, oxazoline group or β-hydroxyalkylamide group. It is preferably used in combination with a compound having two or more in the molecule.
When the optical layer A has a base material made of a glass plate, the curing agent is selected from at least a hydrolyzable silyl group and a silanol group from the viewpoint of further improving the adhesion between the functional layer and the base material. A curing agent having one kind is preferable.

The composition (1) preferably contains a dispersant from the viewpoint of dispersibility of specific particles. Specific examples of the dispersant include fatty acid amides, ester salts of acidic polyamides, acrylic resins, polyolefin oxides, and other polymers having an affinity for specific particles. A commercially available product may be used as the dispersant, and specific examples of the commercially available product include the "Disparon" series (trade name of Kusumoto Kasei Co., Ltd.) and the "DISPERBYK" series (trade name of Big Chemie Co., Ltd.).

When the functional layer is a layer formed by using the composition (1), the functional layer may be produced by molding the composition (1), and the composition (1) may be produced by the optical layer A. It may be produced by coating it on a layer other than the functional layer having it (for example, a base material) and heating and drying it. The functional layer is preferably produced by coating the composition (1) on a layer other than the functional layer of the optical layer A from the viewpoint of the dispersibility of specific particles in the matrix. That is, the composition (1) is preferably a coating material containing a fluorine-containing polymer.
When manufacturing a solar cell module, the above paint is preferably applied on a base material to manufacture an optical layer A, and the obtained optical layer A is pressure-bonded to a sealing layer described later. Therefore, if the functional layer in the optical layer A is a layer formed by coating a paint, the functional layer does not protrude from the end face at the time of pressure bonding with the sealing layer, as compared with the case where the functional layer is a film. But it is preferable.

When the functional layer is produced by molding the composition (1), examples of the molding method include extrusion molding, injection molding, blow molding and the like. In this case, it may be laminated on a layer other than the functional layer of the optical layer A.

When the composition (1) contains a liquid medium and the solid content of the composition (1) is dispersed or dissolved in the medium (water-based paint, solvent-based paint, etc.), specific examples of the coating method include , Spray coating method, squeegee coating method, flow coating method, bar coating method, spin coating method, dip coating method, screen printing method, gravure printing method, die coating method, inkjet method, curtain coating method, method using brush or spatula. Can be mentioned. The composition (1) is preferably a solvent-based coating material in which the polymer is dissolved or dispersed in a solvent from the viewpoint that a functional layer having good dispersibility in the matrix can be formed.
When the composition (1) is a paint (powder paint or the like) that does not contain a liquid medium, specific examples of the coating method include an electrostatic coating method, an electrostatic spraying method, an electrostatic dipping method, a spraying method, and a fluidized dipping method. Examples include the method, spraying method, spraying method, thermal spraying method, and plasma thermal spraying method.
When the composition (1) is coated on a layer other than the functional layer of the optical layer A to produce a functional layer, after coating, the coating layer formed by coating the composition (1) is heated and dried. It is preferable to form. The heating and drying temperature of the coating layer is usually 0 ° C. to 300 ° C., and the heating and drying time is usually 1 minute to 2 weeks.

When the functional layer is a layer formed by using the composition (1), the optical layer A has a base material and a functional layer directly laminated on at least one surface of the base material, and is a group. The material is preferably a layer made of a surface-treated glass plate. That is, in the above case, at least one surface of the glass plate is surface-treated by a known surface treatment method to obtain a base material, and the composition (1) is placed on at least one surface of the obtained base material. It is preferable to directly paint to form a functional layer to obtain an optical layer A. In particular, when the surface treatment is the application of a silane coupling agent or the like, the —Si—OH groups of the glass plate and the —Si—OH groups of the silane coupling agent on the base material interact with each other and the surface. Since the treated base material and the functional layer are in close contact with each other, the durability of the optical layer A is excellent.

The optical layer A may be composed of only the functional layer. Further, the optical layer A may have a layer other than the functional layer as long as the effect of the present invention is not impaired. Specific examples of layers other than the functional layer include a base material, an adhesive layer, and an air layer.
Further, the optical layer A may have a plurality of functional layers, or may have a plurality of layers other than the functional layers. Since the optical layer A only needs to have a functional layer, the arrangement order of each layer of the optical layer A can be appropriately selected.
The adhesive layer is, for example, a layer for adhering two or more layers of the optical layer A.
The air layer is, for example, a layer that maintains the optical layer A in a cushioned state when the optical layer A is a bag-shaped film. At this time, the solar cell may be installed inside the optical layer A.

When the optical layer A has a base material, the strength of the optical layer A can be improved.
The base material is preferably arranged on the incident surface side of sunlight rather than the functional layer.

The average thickness of the base material can be arbitrarily set from the design wind pressure of the building and the like. The average thickness of the base material is preferably 0.7 mm or more, more preferably 1.0 mm or more, and particularly preferably 2.0 mm or more. The average thickness of the base material is preferably 9.7 mm or less, more preferably 8.0 mm or less, and particularly preferably 6.0 mm or less. When the average thickness is 0.7 mm or more, the durability is high and the optical layer A is less likely to crack. When the average thickness is 9.7 mm or less, the optical layer A becomes lightweight, so that the solar cell module is preferably used for the wall surface and the window of the building.
The average thickness of the base material is an arithmetic mean value of the thickness measured using a thickness gauge.

The base material is preferably made of a material that does not reduce the near-infrared light transmittance of the optical layer A. Specifically, the base material was defined as the near-infrared light average transmittance calculated by simply averaging the near-infrared light transmittance in increments of 5 nm in the near-infrared light region having a wavelength of 780 to 1,500 nm. Occasionally, the near-infrared light average transmittance is preferably 50% or more, more preferably 85% or more, and particularly preferably 100%.
Examples of the material constituting the base material include an organic material and an inorganic material. The base material is preferably a glass plate or a resin molded product from the viewpoint of near-infrared light transmittance, and a glass plate is particularly preferable.

Specific examples of the glass plate include at least one selected from the group consisting of soda lime silicate glass, quartz glass, crystal glass, non-alkali glass, aluminosilicate glass, borosilicate glass, and barium borosilicate glass. Soda lime silicate glass is preferable because of its high infrared light transmittance.
Specific examples of soda lime silicate glass include 60 to 75% by mass of SiO ₂ , 0 to 3% by mass of Al ₂ O ₃ , 0 to 15% by mass or less of CaO, and 0 to 12% by mass in terms of oxide. MgO, and include glass having a composition of Na ₂ O 5-20% by weight. Here, SiO ₂ is the main component of the soda lime silicate glass.
Soda-lime silicate glass, in addition to the above _{_{materials, K 2 O, TiO 2,}} ZrO 2 and at least one material may further contain a selected from the group consisting of LiO _2.
In addition, the soda lime silicate glass may further contain a fining agent (for example, SO ₃ , SnO ₂ , Sb ₂ O ₃ ).

The glass plate may be a tempered glass plate that has been subjected to a strengthening treatment. A tempered glass plate is preferable because it is less likely to break than a glass plate that has not been subjected to the tempering treatment. The tempered glass plate includes, for example, a surface layer having a residual compressive stress, a back surface layer having a residual compressive stress, and an intermediate layer formed between the front surface layer and the back surface layer and having a residual tensile stress. Is used.
Specific examples of the strengthening treatment include a chemical strengthening treatment performed by a known ion exchange method and the like, and a physical strengthening treatment performed by a known air cooling strengthening method and the like. The chemically strengthened glass plate has sufficient strength because the value of the residual compressive stress of the front surface layer or the back surface layer can be increased even when the plate thickness is thin.

The resin molded product is a resin molded into a plate shape, a film shape, or the like. Specific examples of the resin include fluororesin, alkyd resin, aminoalkyd resin, polyester resin, epoxy resin, urethane resin, epoxy polyester resin, vinyl acetate resin, (meth) acrylic resin, vinyl chloride resin, phenol resin, and modified polyester resin. , Acrylic silicone resin, silicone resin and the like. As the resin molded product, a fluororesin film is preferable from the viewpoint of weather resistance and near-infrared light transmittance.

The base material may be a layer obtained by surface-treating the above material from the viewpoint of adhesion to a layer other than the base material. As a surface treatment method, a known method can be used. Specifically, activation treatment (plasma method, vapor deposition method, acid treatment, base treatment, etc.), chemical conversion treatment, material surface polishing, sander treatment, pore treatment, etc. Examples include blast treatment and primer treatment.
The base material is particularly preferably a layer made of a surface-treated glass plate. In this case, the surface treatment method is preferably primer treatment (particularly, application of a primer agent).
Specific examples of the primer agent include a silane coupling agent (particularly, alkoxysilane, etc.), a titanium coupling agent, an epoxy resin, a (meth) acrylic resin, and a polyester resin, and when the surface treatment material is a glass plate. , Silane coupling agent or titanium coupling agent is preferable.

<Second embodiment>
The optical layer of the second embodiment is an optical layer used by being arranged on the incident surface side of sunlight with respect to the solar cell, has a functional layer containing specific hollow particles, and has a thickness of the functional layer. Is 1 to 1,000 μm. In the present specification, the optical layer of the second embodiment is also referred to as "optical layer B".
The optical layer B is the same as the optical layer A except that it has a functional layer containing specific hollow particles instead of the functional layer containing specific zirconia particles. In the following, the differences from the optical layer A will be mainly described.

Physical properties of optical layer B (L ^* value, a ^* value, b ^* value, stimulus purity, visible light average transmittance (V1), visible light average scattering transmittance (V2), visible light scattering rate (V3), near red The definitions and suitable values of the external light average transmittance (N1), the near-infrared light average scattering transmittance (N2), the near-infrared light scattering rate (N3) and the refractive light) are the same as the physical properties of the optical layer A, respectively. Is.

The value of each physical property in the optical layer B can be adjusted by, for example, the particle size or the amount of the specific hollow particles added, or the thickness of the optical layer B.

The thickness of the optical layer B and the thickness of the functional layer of the optical layer B are the same as the thickness of the optical layer A and the thickness of the functional layer of the optical layer A, and are measured by the same method as that of the optical layer A. The optics.

The functional layer included in the optical layer B contains specific hollow particles.
The specific hollow particles are particles having a shell layer composed of an inorganic oxide containing a Si atom and having voids inside the shell layer.
It can be confirmed, for example, by observation with a transmission electron microscope (TEM) that the specific hollow particles have voids inside the shell layer.
The shape of the hollow particles is preferably spherical, preferably true spherical.

The average primary particle diameter of the specific hollow particles is 120 to 30,000 nm, preferably 150 to 20,000 nm, more preferably 200 to 15,000 nm, and particularly preferably 200 to 1,000 nm and 300 to 1,000 nm. When the average primary particle size is 120 nm or more, the concealing property of the solar cell is more excellent. When the average primary particle size is 30,000 nm or less, at least one of an optical layer B having a better white appearance and a solar cell module having a higher power generation efficiency can be obtained is satisfied. , There is less risk of particles breaking when forming the functional layer.

The cumulative 50% diameter of the specific hollow particles based on the volume is preferably 0.2 to 100 μm, more preferably 0.2 to 20 μm, and particularly preferably 0.2 to 8 μm. When it is 0.2 μm or more, the concealing property of the solar cell is more excellent. If it is 100 μm or less, it is possible to satisfy at least one of the fact that the optical layer B exhibiting a more excellent white appearance can be obtained and that the solar cell module having more excellent power generation efficiency can be obtained.

The specific surface area of the specific hollow particles is preferably 0.1 ~ 1,000m ² / g, more preferably 1.0 ~ 300m ² / g, particularly preferably 10 ~ 100m ² / g. If it is within the above range, the shell becomes dense, and there is little possibility that resin or the like invades the inside and the hollow structure is lost.

The density of the specific hollow particles is preferably 0.2 to 1.5 g / cm ³ and particularly preferably 0.4 to 1.0 g / cm ³ in terms of dispersibility.

The ratio of the average thickness of the shell of the specific hollow particles to the average primary particle diameter of the specific hollow particles is preferably 0.01 to 0.3, more preferably 0.02 to 0.2, and 0.03 to 0. 1 is particularly preferable. If it is 0.01 or more, the strength of the specific hollow particles is excellent. If it is 0.3 or less, the volume of the voids inside the shell layer can be sufficiently secured, so that the characteristics as hollow particles can be exhibited well.
The average thickness of the shells is the same as the measurement of the average primary particle size. SEM photographs of the particles are taken using a scanning electron microscope, and the measured values of the thickness of the shells of 100 individual particles are arithmetically averaged. Can be obtained.

As the specific hollow particles, hollow particles whose shell layer is made of silica (hereinafter, also referred to as “hollow silica particles”) and hollow particles whose shell layer is made of glass (hereinafter, also referred to as “hollow glass particles”). ) Is preferable, and hollow silica particles are preferable because it is easy to adjust the primary particle size to an appropriate level.

The shell layer of the hollow silica particles is mainly composed of silica, but may contain metal elements such as alkali metal (preferably Na), Ti, and Zr. Among them, the shell layer of hollow silica particles preferably contains an alkali metal because the shell layer becomes dense and hollow silica particles having excellent strength can be obtained.
When the shell layer of the hollow silica particles contains a metal element, the content of the metal element is preferably 500 mass ppm or more, particularly preferably 1,000 mass ppm or more, based on the total mass of the hollow silica particles.

Specific examples of the method for producing the specific hollow silica particles include the method described in International Publication No. 2019/131658.

Hollow glass particles may also be referred to as glass balloons.
Specific examples of the glass constituting the hollow glass particles include borosilicate glass, aluminosilicate glass, sodalime glass, and zinc phosphate glass, and borosilicate glass is preferable.
As the hollow glass particles, commercially available products may be used, and examples thereof include "Sphericel (registered trademark)" series (manufactured by Potters Barotini) and Glass Bubbles (manufactured by 3M).

The content of the specific hollow particles is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, and particularly preferably 1 to 15% by mass with respect to the total mass of the functional layer. When it is 0.1% by mass or more, the concealing property of the solar cell is more excellent. If it is 30% by mass or less, a solar cell module excellent in power generation efficiency can be obtained.

The functional layer of the optical layer B may include a matrix. The matrix is as described with respect to the optical layer A, and the preferred embodiment is also the same, and thus the description thereof will be omitted.

The functional layer of the optical layer B may contain components other than the above. Examples of such a component include the additives described in the optical layer A.

One form of the functional layer in the second embodiment is a layer formed by using a composition containing at least a polymer (particularly, a fluorine-containing polymer) and specific hollow particles.
The composition in the second embodiment is the same as the composition (1) in the first embodiment except that the specific hollow particles are contained instead of the specific zirconia particles, and the preferred embodiments thereof are also the same. Omit.
The composition in the second embodiment may contain two or more kinds of polymers, and may contain two or more kinds of specific hollow particles.
The method for producing the functional layer using the composition in the second embodiment is the same as the method for producing the functional layer using the composition (1) in the first embodiment, and the preferred embodiment thereof is also the same, and thus the description thereof is omitted. To do.

The optical layer B may be composed of only the functional layer. Further, the optical layer B may have a layer other than the functional layer as long as the effect of the present invention is not impaired. Specific examples of layers other than the functional layer include a base material, an adhesive layer, and an air layer. The base material, the adhesive layer, and the air layer are as described in the optical layer A, and the preferred embodiments thereof are also the same, and thus the description thereof will be omitted.
Further, the optical layer B may have a plurality of functional layers, or may have a plurality of layers other than the functional layers. Since the optical layer B only needs to have a functional layer, the arrangement order of each layer of the optical layer B can be appropriately selected.

The optical layer B has a base material and a functional layer directly laminated on at least one surface of the base material for the same reason as the optical layer A, and is a layer made of a glass plate on which the base material is surface-treated. Is preferable.

The solar cell module of the present invention (hereinafter, also referred to as the present solar cell module) has a solar cell and an optical layer, and the optical layer is located on the incident surface side of sunlight with respect to the solar cell. It is arranged. The optical layer included in the solar cell module is the above-mentioned optical layer A or optical layer B.

FIG. 2 is a cross-sectional view of one aspect of the solar cell module (hereinafter, also referred to as aspect 1).
As shown in FIG. 2, the solar cell module 20 has an optical layer 10 having a base material 110 and a functional layer 120, a plurality of solar cell cells 14, a sealing layer 16, and a back surface protective layer 18. The optical layer 10 is laminated on the sealing layer 16 and is arranged on the incident surface side of the sunlight 40 with respect to the solar cell 14. Each of the plurality of solar cells 14 is sealed by a sealing layer 16.
In the solar cell module 20, since the base material 110 included in the optical layer 10 is the outermost layer, the texture of the base material 110 can be utilized, and the action of the functional layer 120 included in the optical layer 10 makes the solar cell The cell 14 has a white appearance while being excellent in concealment.

The optical layer 10 is used as an optical layer for a solar cell module, and has a design property (specifically, an excellent white appearance and an excellent concealing property of a solar cell) in the solar cell module 20. And weather resistance can be imparted.
In the first aspect, the matrix contained in the functional layer is particularly preferably a fluororesin.
In the first aspect, the base material is preferably a glass plate from the viewpoint of durability of the optical layer.

The solar cell 14 has a first light receiving surface 14A and a second light receiving surface 14B facing the first light receiving surface 14A. The solar cell 14 has a function of converting the light energy received by the first light receiving surface 14A and the second light receiving surface 14B into electrical energy. The solar cell may have the function only on the first light receiving surface, or may have the function on the first light receiving surface and the second light receiving surface.
The solar cell in the present invention is preferably a material having spectral sensitivity in the near infrared region. Specifically, a silicon-based solar cell composed of single crystal silicon or polycrystalline silicon, a compound solar cell composed of GaAs, CIS, CIGS, CdTe, InP, Zn ₃ P ₂ or Cu ₂ S. Can be mentioned. As a solar cell, the CIS solar cell and CIGS are excellent in terms of design of this solar cell module because there is no wiring, can be suitably used as an outer wall material, and are excellent in power generation in the near infrared light region. System solar cells are particularly preferred. When the solar cell has wiring, the wiring is preferably colored, and particularly preferably black, from the viewpoint of the design of the solar cell module.

The peak of the spectral sensitivity of the solar cell in the present invention preferably exists in the wavelength range of 780 to 1,200 nm, and particularly preferably exists in the wavelength range of 780 to 1,000 nm.

Here, FIG. 3 is a graph showing the solar spectrum (solar energy) on the ground and the spectral sensitivity curve of the single crystal silicon-based solar cell.
As shown in FIG. 3, the single crystal silicon solar cell has a high spectral sensitivity even in a wavelength region longer than the wavelength of 780 nm. That is, by using an optical layer (optical layer A or optical layer B) that exhibits high transmittance in a long wavelength region, the design (specifically, an excellent white appearance can be exhibited, and the solar cell can be used. This means that a solar cell module capable of providing excellent concealment) and power generation efficiency can be obtained.

The sealing layer 16 serves to seal the solar cell 14.
Specific examples of the material constituting the sealing layer in the present invention include ethylene-vinyl acetate resin, olefin resin, polyvinyl butyral resin, ionomer resin, and silicone resin. Since the sealing layer is required to have adhesion and protective effect to the solar cell, it typically does not contain the specific zirconia particles and the specific hollow particles in the present invention, or if it contains, it is less than 1% by mass with respect to the resin. It is preferable to have.

The back surface protective layer 18 is a surface side of the solar cell module 20 facing the incident surface side of the sunlight 40 with respect to the solar cell 14 (that is, a surface opposite to the incident surface side of the sunlight 40 in the solar cell 14). It is arranged on the side).
The back surface protective layer in the present invention is preferably a layer that improves the strength and light resistance of the solar cell module. Specific examples of the material constituting the back surface protective layer include the same materials as those constituting the base material described above.
The back surface protective layer is preferably black from the viewpoint of the design of the solar cell module. Specifically, the back surface protective layer is preferably a black glass plate or a glass plate having a black coating.
The black color of the back surface protective layer means that the L ^* value of the back surface protective layer is 0 to 40, preferably 0 to 20, particularly preferably 0 to 10.

FIG. 4 is a cross-sectional view of one aspect of the solar cell module (hereinafter, also referred to as aspect 2). Aspect 2 is the same as the aspect 1 except that the optical layer 10 is arranged so that the functional layer 120 is the outermost layer. That is, the functional layer 120 is arranged on the incident surface side of the sunlight 40 with respect to the base material 110.
Since the details of each layer in the second aspect are the same as those in the first aspect, the description thereof will be omitted.

FIG. 5 is a cross-sectional view of one aspect of the solar cell module (hereinafter, also referred to as aspect 3).
As shown in FIG. 5, the solar cell module 20 includes a first optical layer 10A, a plurality of solar cell cells 14, a first sealing layer 16A, a second sealing layer 16B, and a second optical layer 10B. Have. In the following description, the first optical layer 10A and the second optical layer 10B may be collectively referred to as the optical layer 10. Further, the first sealing layer 16A and the second sealing layer 16B may be collectively referred to as a sealing layer 16. The optical layer 10 is laminated on the sealing layer 16 and is arranged on the incident surface side of the

sunlight

40A and 40B with respect to the solar cell 14. Each of the plurality of solar cells 14 is sealed by the sealing layers 16A and 16B.
The first optical layer 10A has a first base material 110A and a first functional layer 120A arranged on the first base material 110A.
The first optical layer 10A is arranged on the first light receiving surface 14A side of the solar cell 14 and on the incident surface side of sunlight 40A, and is attached on the sealing layer 16A. Further, the second optical layer 10B is arranged on the second light receiving surface 14B side of the solar cell 14, and is attached on the sealing layer 16B.
The second optical layer 10B has a second base material 110B and a second functional layer 120B arranged on the second base material 110B. Since the second base material 110B and the second functional layer 120B are the same as the above-mentioned first base material 110A and the first functional layer 120A, respectively, the description thereof will be omitted.
Aspect 3 is preferably used when sunlight is incident from any surface such as a fence.
Since the details of each layer in the third aspect are the same as those in the first aspect, the description thereof will be omitted.

The solar cell module has been described above with reference to FIGS. 2, 4 and 5. The solar cell module is not limited to the above-described embodiment. That is, the present solar cell module may have at least one kind of arbitrary layer (for example, an adhesive layer, an air layer) within a range which does not impair the effect of the present invention. Further, in the present solar cell module, the optical layer may be arranged on the incident surface side of sunlight with respect to the solar cell, and the stacking order other than that is not limited.
For example, the solar cell module may have an arbitrary layer between the optical layer and the sealing layer. Further, in the present solar cell module, the solar cell may not be sealed by the sealing layer.
When a glass plate is used as the base material, the design of the solar cell module (specifically, it exhibits an excellent white appearance and excellent concealment of the solar cell) and sealing. Aspect 1 is particularly preferable from the viewpoint of adhesiveness between the layer and the optical layer.

FIG. 6 is a schematic plan view showing an example of a solar cell array configured by the present solar cell module.
As shown in FIG. 6, the solar cell array 30 is configured by arranging a plurality of rectangular solar cell modules 20 in a plane and connecting them in series and parallel.
Specific examples of the installation location of the solar cell array of the present invention include the rooftop, roof, and outer wall (for example, wall surface, window) of a building.
The solar cell array of the present invention is excellent in design (specifically, exhibiting an excellent white appearance and excellent concealing property of a solar cell) and power generation efficiency. As described above, it is preferable to use it as a building outer wall material (for example, a wall surface of a building, a window) because of its excellent design.
FIG. 6 shows an aspect in which the solar cell array of the present invention has a rectangular shape, but the shape of the solar cell array of the present invention is not particularly limited.

The building exterior wall material of the present invention has the above-mentioned solar cell module. Therefore, the building exterior wall material of the present invention is excellent in designability (specifically, it exhibits an excellent white appearance and is excellent in concealing the solar cell) and power generation efficiency. Specific examples of exterior wall materials for buildings include curtain walls, wall materials, and windows.

The building of the present invention has the above-mentioned building exterior wall material. Therefore, the building of the present invention is excellent in design (specifically, exhibiting an excellent white appearance and excellent concealing property of the solar cell) and power generation efficiency.

The building of the present invention may have the optical layer of the present invention on the incident surface side of the sunlight of the building outer wall material having the solar cell module, via an intermediate air layer or the like arbitrarily existing. That is, the building of the present invention is a building having a double skin system, and the optical layer of the present invention may be used as the outer skin.

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to the following examples. Examples 1 to 12 are examples, and examples 13 to 16 are comparative examples. The blending amount of each component in the table described later indicates a mass standard.

[Example 1]
Polymer solution F (ethyl 3-ethoxypropionate solution of chlorotrifluoroethylene-vinyl ether copolymer, AGC product LF-9716, solid content concentration: 66.8% by mass) (65.3 g), and Table 1. The particles (39.1 g) described in Example 1 of the above were added, and 30 g of zirconia beads having a diameter of 5 mm were further added, and the mixture was stirred at 2,000 rpm for 20 minutes using a kneader (Sinky's product Awatori Kentarou). Then, a curing agent (Asahi Kasei TPA-B80E, solid content concentration: 80% by mass) (39.6 g) is added, and the mixture is further stirred at 2,000 rpm for 1 minute to remove zirconia beads to form a functional layer. The composition for was obtained.
The obtained composition was used as a base material on one surface of a soda lime silicate glass plate (AGC product JFL, length 150 mm x width 75 mm, average plate thickness: 3.2 mm) on a screen printing machine (Microtech Co., Ltd.). It was painted using MTVC-320) manufactured by Japan. Then, it is dried by heating in a thermostatic chamber at 160 ° C. for 30 minutes and cured to form a glass plate as a base material, a functional layer (average thickness: 28 μm, matrix: fluororesin) arranged on the base material. An optical layer composed of was obtained.

[Examples 2 to 16]
The optical layer in each example was obtained in the same manner as in Example 1 except that the type of particles, the concentration in the functional layer, and the thickness of the functional layer were changed as shown in Tables 1 and 2.

[Details of particles used]
Example 1, Example 2, Example 6: Zirconia particle 1 (Tosoh product TZ-3Y-E, density: 6.05 g / cm ³ , part of Zr is replaced with Y, 3 mol% with respect to Zr. Zirconia particles containing Y)
Examples 3 to 5, Example 7: Zirconia particle 2 (Tosoh product TZ-3YS-E, density: 6.05 g / cm ³ , part of Zr is replaced with Y, and 3 mol% with respect to Zr. Zirconia particles containing Y)
Examples 8-11: Hollow silica particles 1 (hollow silica produced by the method described in Example 10 of WO 2019/131658, density: 0.6 g / cm ³ , shell average thickness: 20 nm).
Example 12: Hollow glass particles 1 (Potters Barotini product 110P8, density: 1.1 g / cm ³ )
Example 13: Alumina particles 1 (Aldrich reagent, density: 3.95 g / cm ³ )
Example 14: Titania particles 1 (Sakai Chemical Co., Ltd. product STR-100A-LP, density: 4.23 g / cm ³ )
Example 15: Zirconia particles 3 (Aldrich reagent 544760-25G, density: 5.68 g / cm ³ )
Example 16: Hollow silica particles 2 (Nittetsu Mining Co., Ltd. product Sirinax SP-PN (b), density: 0.6 g / cm ³ )

[Evaluation method]
The method for measuring each physical property is as described above. Hereinafter, more detailed measurement methods and conditions will be described.

(particle)
<Average primary particle size>
Using a scanning electron microscope (S-4800 manufactured by Hitachi High-Technologies Corporation), SEM photographs of the particles were taken, and 100 major axis diameters of the primary particles in the image were measured. The arithmetic mean value was adopted as the average primary particle size.

<D50>
Cumulative volume-based accumulation using a laser diffraction / scattering particle size distribution measuring device (MT3300EXII manufactured by Microtrac Bell) using a dispersion containing particles dispersed in ion-exchanged water so that the scattering intensity falls within the measurement range. The 50% diameter was measured. The average of the cumulative 50% diameters of the three obtained points was adopted as D50.

<Specific surface area>
The specific surface area was measured by the nitrogen adsorption BET method under degassing conditions at 200 ° C. for 20 minutes using a specific surface area measuring device (HM model-1208 manufactured by Mountech).

(Optical characteristics of optical layer)
The total light transmittance of the optical layer was measured using a spectrophotometer (V-670 manufactured by JASCO Corporation) in a wavelength range of 200 to 1,200 nm in 5 nm increments at a scanning speed of 1,000 nm / min. The optical layer was installed so as to be in contact with the light receiving portion of the integrating sphere, and was set so that light was incident from the glass substrate side. The light source switching was automatic, the switching wavelength was 340.0 nm, and the diffraction grating switching was 850 nm.
For the linear transmittance of the optical layer, a spectrophotometer (V-670 manufactured by JASCO Corporation) is used, and an integrating sphere is used at a scanning speed of 1,000 nm / min in a wavelength range of 200 to 1,500 nm in 5 nm increments. Measured without.

V1 (Visible light average transmittance): Of the total light transmittance obtained by the above measurement, the total light transmittance in increments of 5 nm was calculated and averaged in the visible light region having a wavelength of 400 to 780 nm.
V2 (Visible light average scattering transmittance): From the above visible light average transmittance, among the linear transmittances obtained by the above measurement, the linear transmittance in increments of 5 nm is arithmetically averaged in the visible light region having a wavelength of 400 to 780 nm. The visible light average scattering transmittance was calculated by subtracting the obtained value.
V3 (Visible light scattering rate): The ratio of the visible light average diffusion transmittance divided by the visible light average transmittance was calculated.
N1 (Near Infrared Light Average Transmittance): Of the total light transmittance obtained by the above measurement, the total light transmittance in increments of 5 nm is calculated by arithmetically averaging in the near infrared light region having a wavelength of 780 to 1,200 nm. It was.
N2 (Near Infrared Light Average Diffuse Transmittance): From the near infrared light average transmittance, among the linear transmittances obtained by the above measurement, the linear transmittance in increments of 5 nm in the near infrared region having a wavelength of 780 to 1200 nm. The near-infrared light average diffuse transmittance was calculated by subtracting the value obtained by arithmetically averaging.
N3 (Near-infrared light scattering rate): The ratio of the near-infrared light average diffusion transmittance divided by the near-infrared light average transmittance was calculated.

(Spectroscopic color)
L ^* , a ^* , b ^* and stimulus purity were measured using a spectrocolorimeter (SD6000 manufactured by Nippon Denshoku Kogyo Co., Ltd.). At the time of measurement, a black plate was placed on the back surface of the sample, and water was filled between the black plate and the sample. The measurement light was incident from the glass substrate side.

(Concealment)
Among the optical characteristics of the optical layer, the concealing property of the optical layer was evaluated based on the following criteria for the average visible light transmittance. The lower the average visible light transmittance, the better the concealment property. Therefore, it is possible to manufacture a solar cell module having a high design because the solar cell is hard to see.
S: Less than 30% A: 30% or more and less than 60% B: 60% or more and less than 80% C: 80% or more

(Color tone)
Among the optical characteristics of the optical layer, the color tone of the optical layer was evaluated based on the following criteria for stimulation purity. The lower the stimulation purity, the closer the color tone of the optical layer is to white, so that a solar cell module having a white appearance can be manufactured.
S: Less than 4.0 A: 4.0 or more and less than 6.0 B: 6.0 or more and less than 12.0 C: 12.0 or more

(Power generation efficiency)
Visible light (400 to 780 nm) and near infrared light (780 to 1,200 nm) have a power generation contribution of 30% and 70%, respectively, and the visible light average transmittance and the near infrared light average. Multiplying the transmittances was added up to calculate the expected power generation efficiency for a single crystal silicon cell using an uncoated soda lime silicate glass plate (AGC product JFL, average plate thickness: 3.2 mm).

Details are shown in Tables 1 and 2.

As shown in Tables 1 and 2, if an optical layer containing zirconia particles having a predetermined average primary particle size or hollow particles of silica or glass having a predetermined average primary particle size and having a functional layer having a predetermined thickness is used. It has been found that a solar cell module having excellent concealing property of a solar cell, exhibiting a white appearance, and excellent power generation efficiency can be obtained (Examples 1 to 12).
On the other hand, when it contains alumina particles or titania particles, or when it contains zirconia particles or hollow silica particles whose average primary particle size is outside the range of the present invention, the solar cell has excellent hiding power and exhibits a white appearance. Moreover, a solar cell module having excellent power generation efficiency could not be obtained (Examples 12 to 16).

10 Optical layer 10A 1st optical layer 10B 2nd optical layer 110 base material 110A 1st base material 110B 2nd base material 120 functional layer 120A 1st functional layer 120B 2nd functional layer 14 solar cell 14A 1st light receiving surface 14B second 2 Light receiving surface 16 Sealing layer 18 Back surface protective layer 20 Solar cell module 30

Solar cell array

40, 40A, 40B Sunlight

The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2019-141081, filed on July 31, 2019, are cited here as disclosure of the specification of the present invention. It is something to incorporate.

Claims

An optical layer used by being arranged on the incident surface side of sunlight with respect to a solar cell.
The optical layer has an average primary particle size of 40 to 500 nm, zirconia particles in which some of the constituent elements may be replaced with elements other than Zr, or an average primary particle size of 120 to 30,000 nm. Has a functional layer containing hollow particles of an inorganic oxide containing Si atoms,
An optical layer, characterized in that the thickness of the functional layer is 1 to 1,000 μm.
The optical layer according to claim 1, wherein the cumulative 50% diameter of the zirconia particles based on the volume is 0.1 to 5 μm.
The optical layer according to claim 1 or 2, wherein the specific surface area of the zirconia particles is 0.5 to 100 m 2 / g.
The optical layer according to any one of claims 1 to 3, wherein the content of the zirconia particles is 1 to 80% by mass with respect to the total mass of the functional layer.
The optical layer according to any one of claims 1 to 4, wherein a part of the constituent elements in the zirconia is substituted with Y.
The optical layer according to any one of claims 1 to 5, wherein the hollow particles are at least one of hollow particles whose shell layer is made of silica and hollow particles whose shell layer is made of glass.
The optical layer according to claim 1, wherein the volume-based cumulative 50% diameter of the hollow particles is 0.2 to 100 μm.
The optical layer according to claim 1 or 7, wherein the specific surface area of the hollow particles is 0.1 to 1,000 m 2 / g.
The optical layer according to any one of claims 1, 7 and 8, wherein the content of the hollow particles is 0.1 to 30% by mass with respect to the total mass of the functional layer.
The optics according to any one of claims 1 and 7 to 9, wherein the ratio of the average thickness of the shell layer of the hollow particles to the average primary particle diameter of the hollow particles is 0.01 to 0.3. layer.
The invention according to any one of claims 1 to 10, wherein the optical layer further has a base material made of a glass plate, and the base material is arranged on the incident surface side of sunlight with respect to the functional layer. Optical layer.
The optical layer according to any one of claims 1 to 11, wherein the functional layer further contains a fluororesin.
It has a solar cell and an optical layer according to any one of claims 1 to 12, and the optical layer is arranged on the incident surface side of sunlight with respect to the solar cell. Solar cell module.
The solar cell module further has a back surface protective layer arranged on the side opposite to the incident surface side of sunlight in the solar cell.
The solar cell module according to claim 13, wherein the back surface protective layer is black.
A building exterior wall material having the solar cell module according to claim 13 or 14.
A building having the building exterior wall material according to claim 15.