JP2016100505A - Sealant for solar battery, and solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealant for a solar battery, which is superior in workability, corrosion resistance, heat resistance, low water absorbency, strength and toughness, and which makes possible to appropriately maintain the effect of the increase in power generation efficiency even in the case of using a solar battery over a long period of time.SOLUTION: A sealant for a solar battery comprises: a resin composition including a polyvinyl acetal resin (A), a plasticizer (B) and an amorphous polymer (C); and a wavelength conversion material. In the resin composition, the mass ratio of the polyvinyl acetal resin (A) vs. the amorphous polymer (C) is 70:30 to 35:65. The wavelength conversion material comprises particles including an inorganic fluorescent material expressed by BaMgAlO:Eu,Mn(where "a" is 0.05-0.25, and "b" is 0.10-0.40), and a transparent material. The content of the inorganic fluorescent material is 0.0001-0.005 pt.mass to 100 pts.mass of the resin composition.SELECTED DRAWING: None

Description

  The present invention relates to a solar cell sealing material and a solar cell module.

  In recent years, solar cells that directly convert sunlight into electric energy have been widely used in terms of effective use of resources and prevention of environmental pollution, and further development of solar cells is being promoted.

  A solar cell module usually has a photoelectric semiconductor layer (hereinafter sometimes referred to as a solar cell element) having a transparent cover for protecting the influence from the outside. This solar cell element is usually installed between a glass plate and a hard cover plate such as glass or a back sheet, and is fixed by a sealing material having adhesiveness.

  Generally, since a solar cell element is extremely fragile, it has been proposed to use an ethylene-vinyl acetate copolymer (EVA) containing an organic peroxide as a raw material for a sealing material (for example, Patent Document 1). And 2). In the uncured state, the EVA can be adjusted to have a low viscosity so as to be able to surround the solar cell element without including bubbles, and after the crosslinking reaction with the subsequent curing agent or crosslinking agent, it is at a certain level. In order to show the above mechanical strength, it is suitable as a raw material of a sealing material. A problem of a solar cell module using EVA is corrosion of metal components by acetic acid generated by hydrolysis or thermal decomposition of EVA. Another problem in the case of using EVA is that it is not suitable for manufacturing a solar cell module by a roll-to-roll process because it is necessary to laminate while proceeding with a crosslinking reaction. The curable casting resin is difficult to control the embedding and curing of the solar cell element, and is hardly employed in the actual production of the solar cell module. Furthermore, some curable casting resins generate bubbles or peel off after several years from production.

  Therefore, it has been proposed to use a polyvinyl acetal resin such as polyvinyl butyral (PVB) which is a thermoplastic resin as a sealing material (see, for example, Patent Document 3). The polyvinyl acetal resin has an advantage that the content of acetic acid units capable of generating an acid component is smaller than that of EVA, so that the metal component is hardly corroded. Further, since it is a thermoplastic resin, it has a high viscosity at the flow start temperature, and there is little concern that the resin will flow out from the glass edge when laminating, and the device and the glass edge will be soiled. And also from a mechanical viewpoint, the sealing material using polyvinyl acetal resin is excellent in the adhesiveness with respect to glass, and penetration resistance. Furthermore, since a crosslinking step is not required, it is possible to manufacture a solar cell module by a roll-to-roll process.

  It is a polyvinyl acetal resin that has such excellent mechanical properties and excellent processability, but it is known that its heat resistance is inadequate (the mechanical properties are greatly deteriorated in a high-temperature environment) and its water absorption is large. ing. In general, it has been found that when the glass transition temperature Tg or higher is reached, the film softens, and in particular, in the vicinity of 100 ° C., sufficient performance cannot be exhibited. In polyvinyl acetal resin, it is conceivable to reduce the amount of plasticizer, increase the degree of polymerization of the resin, introduce a cross-linked structure, etc. in order to impart heat resistance. Due to gelation problems, this is not expected to be an effective means. Similar studies have been conducted on the above-mentioned EVA-based encapsulants, including studies on crosslinking by electron beam irradiation, combined use of organic peroxides, silane coupling agents, etc., and addition of mechanical properties by crystalline polyolefin composites. It has been. However, when cross-linking with an electron beam, when using an organic peroxide, a silane coupling agent, etc., it is difficult to control the reaction (adjustment of temperature, time, amount of addition, etc.), so it takes time and effort to manufacture. This is one of the factors that increase the manufacturing cost. In the case of performing the crystalline polyolefin composite, by combining the crystalline component with the amorphous matrix, the transparency is deteriorated and the total light transmittance important for the solar cell sealing material is deteriorated. Absent.

  By the way, in general, any type of solar cell element such as a silicon crystal power generation element has a problem that the spectral sensitivity is low with respect to light in the ultraviolet region and solar energy cannot be effectively utilized. It has been. In order to solve this problem, a technology to improve the power generation efficiency of solar cells by using a material (wavelength conversion material) that converts light in the ultraviolet region into light in the visible region or near infrared region is proposed. Has been. Specifically, by providing a layer containing a fluorescent material on the light-receiving surface side of the solar cell element, the wavelength of ultraviolet light in the solar spectrum is converted to a wavelength that greatly contributes to power generation of the solar cell element. A method (for example, refer to Patent Document 4) or the like in which a method of emitting light (for example, a rare earth complex emitting fluorescence of 500 nm to 1000 nm) is included in a sealing material (sealing material) of a solar cell module has been proposed.

  However, the organic fluorescent material described in Patent Document 4 is greatly deteriorated by ultraviolet rays and heat, and when used for a solar cell that is used outdoors for a long time, the effect of wavelength conversion is reduced, and the power generation efficiency is reduced. There has been a problem that the improving effect tends to decrease.

JP 58-23870 A Japanese Patent Laid-Open No. 6-177412 JP 2006-13505 A JP 2008-195664 A

  The object of the present invention is to provide excellent processing characteristics, corrosion resistance, heat resistance, low water absorption, strength and toughness, and to improve the power generation efficiency by the wavelength conversion material even when the solar cell is used over a long period of time. It is providing the sealing material for solar cells which can fully be maintained.

Specific means for solving the above-described problems are as follows.
<1> A polyvinyl acetal resin (A) in the resin composition comprising a resin composition containing a polyvinyl acetal resin (A), a plasticizer (B) and an amorphous polymer (C), and a wavelength conversion material. Inorganic fluorescent substance and transparent whose mass ratio ((A) :( C)) with an amorphous polymer (C) is 70: 30-35: 65, and whose said wavelength conversion material is represented by following formula (I) A sealing material for solar cells, which is a particle containing a material, and the content of the inorganic fluorescent material is 0.0001 parts by mass to 0.005 parts by mass with respect to 100 parts by mass of the resin composition.
_{Ba 1-a Mg 1-b} Al 10 O 17: Eu a, Mn b (I)
(In the formula, a is 0.05 to 0.25, and b is 0.10 to 0.40.)

<2> The solar cell sealing material according to <1>, wherein the glass transition temperature (Tgc) of the amorphous polymer (C) is 5 ° C. or more higher than the glass transition temperature (Tga) of the polyvinyl acetal resin (A). .

<3> In a state where a 0.7 mm thick test piece is sandwiched between two 1.3 mm thick glass plates, the total light transmittance measured in accordance with JIS K7105 is 85% or more. The sealing material for solar cells as described in 1> or <2>.

<4> The ratio (E '@ 25 ° C / E' @ 100 ° C) of the storage elastic modulus at 25 ° C (E '@ 25 ° C) and the storage elastic modulus at 100 ° C (E' @ 100 ° C) is 75 or less. The sealing material for solar cells according to any one of <1> to <3>.

<5> The solar cell according to any one of <1> to <4>, wherein the amorphous polymer (C) is a polymer obtained by polymerizing a monomer containing an alkyl (meth) acrylate. Sealing material.

<6> The solar cell encapsulant according to any one of <1> to <5>, wherein the transparent material is a (meth) acrylic resin.

<7> The solar cell sealing material according to any one of <1> to <6>, wherein the wavelength conversion material has an average particle diameter of 2 μm to 150 μm.

<8> The solar cell encapsulant according to any one of <1> to <7>, wherein the inorganic fluorescent substance is surface-treated with a silane coupling agent.

<9> The content of the inorganic fluorescent substance in the wavelength conversion material is 0.5% by mass to 1.5% by mass with respect to the mass of the wavelength conversion material, and any one of <1> to <8>. The solar cell sealing material according to Item.

<10> The sealing material for solar cells according to any one of <1> to <9>, wherein the inorganic fluorescent substance has a volume average particle diameter of 0.1 μm to 10 μm.

<11> The solar cell sealing material according to any one of <1> to <10>, wherein a refractive index of the inorganic fluorescent material is 1.5 to 2.2.

The solar cell module which has a <12> solar cell element and the sealing material for solar cells of any one of <1>-<11> provided in the light-receiving surface side of the said solar cell element.

  According to the present invention, the processing characteristics, corrosion resistance, heat resistance, low water absorption, strength and toughness are excellent, and even when the solar cell is used over a long period of time, the effect of improving the power generation efficiency by the wavelength conversion material is sufficiently obtained. A solar cell encapsulant that can be maintained, and a solar cell module using the same can be provided.

  In the present specification, a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. The content of a certain component means the total amount of the plurality of substances when there are a plurality of substances corresponding to the component, unless otherwise specified. The term “layer” includes not only the configuration of the shape formed on the entire surface when observed as a plan view, but also the configuration of the shape formed in part. The term “stacked” indicates that the layers are stacked, and two or more layers may be bonded, or two or more layers may be detachable. In this specification, (meth) acryl means acryl, methacryl or a mixture thereof, (meth) acrylic resin means an acrylic resin, methacrylic resin or a mixture thereof, and (meth) acrylic monomer is , Acrylic monomer, methacrylic monomer or a mixture thereof.

<Sealant for solar cell>
The solar cell encapsulant (hereinafter also referred to as encapsulant) of the present invention includes a resin composition containing a polyvinyl acetal resin (A), a plasticizer (B) and an amorphous polymer (C), and wavelength conversion. The mass ratio ((A) :( C)) of the polyvinyl acetal resin (A) and the amorphous polymer (C) in the resin composition is 70:30 to 35:65, and the wavelength The conversion material is a particle containing an inorganic fluorescent material represented by the following formula (I) and a transparent material, and the content of the inorganic fluorescent material is 0.0001 to 0.005 with respect to 100 parts by mass of the resin composition. Part by mass.

_{Ba 1-a Mg 1-b} Al 10 O 17: Eu a, Mn b (I)
(In the formula, a is 0.05 to 0.25, and b is 0.10 to 0.40.)

The sealing material of the present invention includes a polyvinyl acetal resin and an amorphous polymer. By using a polyvinyl acetal resin as the sealing material, it is possible to provide a sealing material that is superior in processing characteristics and corrosion resistance as compared with a sealing material that uses EVA. Moreover, the sealing material which is excellent in heat resistance can be provided compared with the sealing material using only a polyvinyl acetal resin by including a polyvinyl acetal resin and an amorphous polymer. Moreover, when the mass ratio of the polyvinyl acetal resin and the amorphous polymer is 70:30 to 35:65, it is possible to provide a sealing material excellent in low water absorption and excellent in strength and toughness.
Furthermore, the sealing material of this invention contains the particle | grains containing an inorganic fluorescent material and a transparent material in a specific quantity as a wavelength conversion material. Thereby, the improvement effect of the power generation efficiency of a solar cell can fully be maintained over a long period of time.

[Polyvinyl acetal resin (A)]
The sealing material of the present invention contains a polyvinyl acetal resin. The polyvinyl acetal resin is a resin obtained by acetalizing polyvinyl alcohol with an aldehyde compound, and is produced by a known method.

  Polyvinyl alcohol used as a raw material for the polyvinyl acetal resin can be obtained, for example, by polymerizing a vinyl ester monomer and saponifying the obtained polymer.

  Examples of vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatate, vinyl caproate, vinyl caprylate, vinyl laurate, vinyl palmitate, Examples include vinyl stearate, vinyl oleate, and vinyl benzoate. Of these, vinyl acetate is preferred. A vinyl ester monomer may be used individually by 1 type, or may use 2 or more types together.

  When the polyvinyl acetal resin is obtained by polymerizing a vinyl ester monomer, it can be copolymerized with other monomers within a range not impairing the gist of the present invention. Other monomers include α-olefins such as ethylene, propylene, n-butene and isobutylene; acrylic acid or salts thereof; methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, acrylic Acrylic acid ester monomers such as n-butyl acid, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate; methacrylic acid and salts thereof; methyl methacrylate, methacryl Methacrylic acid such as ethyl acetate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate Ester monomer; Luamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid and its salt, acrylamidopropyldimethylamine and its salt or its quaternary salt, N-methylolacrylamide and its Acrylamide and acrylamide derivatives such as derivatives; methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and salts thereof, methacrylamidepropyldimethylamine and salts thereof or quaternary salts thereof, N-methylol Methacrylamide and methacrylamide derivatives such as methacrylamide or derivatives thereof; methyl vinyl ether, ethyl vinyl ether, n-propylene Vinyl ether monomers such as ruvinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether; nitrile monomers such as acrylonitrile and methacrylonitrile; vinyl chloride, Vinyl halide monomers such as vinyl fluoride; vinylidene halides such as vinylidene chloride and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; maleic acid and its salts, maleate esters and maleic anhydride; vinyl Examples thereof include vinylsilyl compounds such as trimethoxysilane; isopropenyl acetate and the like. When these monomers are used in combination with a vinyl ester monomer, the proportion is usually less than 20 mol% relative to 100 mol% of the vinyl ester monomer, and more preferably less than 10 mol%. .

  As a method for polymerizing the above-mentioned monomers, conventionally known methods such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method can be applied. The polymerization initiator is appropriately selected from azo initiators, peroxide initiators, redox initiators and the like according to the polymerization method. At this time, the polymerization may be performed in the presence of a thiol compound such as thiol acetic acid or mercaptopropionic acid, or the polymerization may be performed in the presence of another chain transfer agent.

  As a method for the saponification reaction, alcoholysis or hydrolysis using a conventionally known alkali catalyst or acid catalyst can be applied. Among these, a saponification reaction using a caustic soda catalyst with methanol as a solvent is simple and most preferable.

  The aldehyde compound used for the acetalization of the polyvinyl alcohol is not particularly limited. Preferably, a C1-C12 aldehyde compound is mentioned. Examples of the aldehyde compound having 1 to 12 carbon atoms include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, hexylaldehyde, benzaldehyde and the like. Among these, a C1-C6 saturated alkyl aldehyde compound is more preferable, and a C1-C4 saturated alkyl aldehyde compound is more preferable. Specifically, butyraldehyde and acetaldehyde are particularly preferable from the viewpoint of the mechanical properties of the film when used as a sealing material. An aldehyde compound may be used individually by 1 type, or may use 2 or more types together. Furthermore, you may use together the polyfunctional aldehyde compound which has a 2 or more aldehyde group, the aldehyde compound which has functional groups other than an aldehyde group, etc. in the range used as 20 mass% or less of all the aldehyde compounds.

  The method for producing the polyvinyl acetal resin is not particularly limited. For example, a method of reacting an aldehyde compound in the presence of a catalyst in a polyvinyl alcohol solution can be mentioned.

  When producing a polyvinyl acetal resin in a polyvinyl alcohol solution by a method of reacting an aldehyde compound under acidic conditions, the solvent used in the polyvinyl alcohol solution is not particularly limited. From the viewpoint of industrially producing a large amount of polyvinyl acetal resin, it is preferable to use water as a solvent. In this case, it is preferable that polyvinyl alcohol is sufficiently dissolved in water at a high temperature in advance, for example, at a temperature of 90 ° C. or higher before the reaction. Moreover, 5 mass%-40 mass% are preferable, as for the density | concentration of the polyvinyl alcohol in aqueous solution, 5 mass%-20 mass% are more preferable, and 8 mass%-15 mass% are more preferable. Good productivity is easily maintained when the concentration of the polyvinyl alcohol is 5% by mass or more. When the concentration of the polyvinyl alcohol is 40% by mass or less, stirring during the reaction is easy, gelation due to intermolecular hydrogen bonding of the polyvinyl alcohol hardly occurs, and unevenness in the reaction is difficult to occur.

  An acidic compound is mentioned as a catalyst for making an aldehyde compound react in the polyvinyl alcohol aqueous solution. The kind of acidic compound is not particularly limited, and any of organic acids and inorganic acids can be used. Examples of the organic acid include acetic acid and p-toluenesulfonic acid, and examples of the inorganic acid include nitric acid, sulfuric acid, hydrochloric acid, and carbonic acid. Of these, inorganic acids are preferred, and hydrochloric acid, sulfuric acid and nitric acid are more preferred because sufficient reaction rates can be obtained and washing after the reaction is easy. The concentration of the catalyst used in the reaction depends on the type of catalyst used, but when the catalyst is hydrochloric acid, sulfuric acid or nitric acid, 0.01 mol / L to 5 mol / L is preferable, and 0.1 mol / L to 2 mol. / L is more preferable. When the acid concentration is 0.01 mol / L or more, a good reaction rate can be maintained, and it can be avoided that it takes time to obtain a polyvinyl acetal resin having the desired degree of acetalization and physical properties. On the other hand, when the concentration of the acid is 5 mol / L or less, the reaction is easily controlled and dimers and trimers of the aldehyde compound are hardly generated.

  As a procedure for reacting an aldehyde compound with an aqueous polyvinyl alcohol solution, a known method may be mentioned. For example, the method of adding an aldehyde compound after adding a catalyst to polyvinyl alcohol aqueous solution, the method of adding a catalyst after adding an aldehyde compound previously, etc. are mentioned. Further, a method of adding or sequentially adding aldehyde compounds or catalysts, a method of adding them in portions, a method of adding a mixed solution of an aqueous polyvinyl alcohol solution and an aldehyde compound or a catalyst to a solution containing the catalyst or the aldehyde compound, and the like are also included.

  The reaction temperature is not particularly limited but is preferably 0 ° C to 80 ° C. In order to obtain a polyvinyl acetal resin which is a porous particle easy to wash after the reaction, it is relatively low temperature (for example, 0 ° C. to 40 ° C., preferably 5 ° C. to 20 ° C.) until the polyvinyl acetal resin is precipitated during the reaction. (C). After the polyvinyl acetal resin is deposited, the reaction temperature is preferably increased (for example, 50 ° C. to 80 ° C.) in order to drive the reaction, and more preferably 65 ° C. to 75 ° C. from the viewpoint of productivity.

  The polyvinyl acetal resin deposited by the reaction is preferably porous particles in order to efficiently remove the remaining catalyst, aldehyde compound, and the like. Polyvinyl acetal resin, which is a porous particle, is obtained by adjusting the viscosity of the reaction liquid, the stirring speed, the shape of the stirring blade, the shape of the reaction vessel, the reaction temperature, the reaction speed, the method of adding the catalyst and the aldehyde compound, etc. Can do. For example, when the reaction temperature is within the above range, the polyvinyl acetal resin is difficult to be fused and easily becomes porous.

  The degree of acetalization of the polyvinyl acetal resin is preferably 35 mol% to 95 mol%, and more preferably 40 mol% to 90 mol%. When the degree of acetalization is 35 mol% or more, transparency is good and sufficient flexibility is easily obtained. When the degree of acetalization is less than 95 mol%, the production process is easy to pass and the cost increase is easily suppressed.

  In the polyvinyl acetal resin, the amount of vinyl alcohol units measured based on the provisions of JIS K6728: 1977 is preferably 5 mol% to 34 mol%, more preferably 7 mol% to 32 mol%, more preferably 10 mol. It is more preferable that it is% -30 mol%. When the amount of the vinyl alcohol unit is 34 mol% or less, the hygroscopicity is kept low, and in the solar cell module described later, metal corrosion due to absorbed water, deterioration of insulation, peeling of the polyvinyl acetal resin from the base material, etc. It is easy to suppress the occurrence of On the other hand, when the amount of the vinyl alcohol unit is 5 mol% or more, it is easy to suppress the occurrence of problems such as a decrease in mechanical strength of the polyvinyl acetal resin and poor adhesion to the substrate.

  In the polyvinyl acetal resin, the amount of vinyl ester units measured according to JIS K6728: 1977 is preferably 10 mol% or less, more preferably 9 mol% or less, and further preferably 8 mol% or less. In particular, when the vinyl ester unit is a vinyl acetate unit, if the amount is 10 mol% or less, it is possible to effectively suppress the generation of acetic acid, which is a corrosive substance, due to decomposition by heat, hydrolysis by moisture, etc. Further, it is possible to effectively suppress coloring due to olefin generated by the elimination of acetic acid.

  The total amount of chloride ions, sulfate ions and nitrate ions derived from the acetalization catalyst contained in the polyvinyl acetal resin is preferably 100 ppm or less, more preferably 50 ppm or less, and 20 ppm or less. More preferably. Since these strong acid ions can cause corrosion of metal components used in solar cell modules and the like to be described later, when the amount is 100 ppm or less, corrosion of metal components can be effectively suppressed.

[Plasticizer (B)]
The sealing material of the present invention contains a plasticizer. The plasticizer used in the present invention is not particularly limited. For example, di (2-butoxyethyl) adipate (DBEA), di (2-butoxyethyl) sebacate (DBES), di (2-butoxyethyl) azelate, di (2-butoxyethyl) glutarate, adipic acid Di (2-butoxyethoxyethyl) (DBEEA), di (2-butoxyethoxyethyl) sebacate (DBEES), di (2-butoxyethoxyethyl) azelate, di (2-butoxyethoxyethyl) glutarate, adipic acid Di (2-hexoxyethyl), di (2-hexoxyethyl) sebacate, azelaine di (2-hexoxyethyl), di (2-hexoxyethyl) glutarate, di (2-hexoxyethoxyethyl) adipate, di (2- Hexoxyethoxyethyl), azelaic acid di (2-hexoxyethoxy) Chill), di (2-hexoxyethoxyethyl) glutarate, di (2-butoxyethyl) phthalate, di (2-butoxyethoxyethyl) phthalate, triethylene glycol di (2-ethylhexanoate) (3GO) ), Tetraethylene glycol di (2-ethylhexanoate) (4GO), 1,2-cyclohexanedicarboxylic acid diisononyl (DINCH), and the like. Among these, it is preferable to use a high-boiling point plasticizer in consideration of the case where the high-temperature laminating step is performed. As high-boiling plasticizers, triethylene glycol di (2-ethylhexanoate) (3GO), tetraethylene glycol di (2-ethylhexanoate) (4GO), di (2-butoxyethoxyethyl) adipate (DBEEA), di (2-butoxyethoxyethyl) sebacate (DBEES), diisononyl 1,2-cyclohexanedicarboxylate (DINCH) and the like. The addition amount of the plasticizer is preferably 3 parts by mass to 85 parts by mass, and preferably 5 parts by mass to 80 parts by mass with respect to 100 parts by mass of the total amount of the polyvinyl acetal resin and the amorphous polymer described later. Is more preferable. A plasticizer may be used individually by 1 type, or may use 2 or more types together.

[Amorphous polymer (C)]
The sealing material of the present invention includes an amorphous polymer. In this specification, an amorphous polymer means a polymer having no melting point measurable in differential scanning calorimetry (DSC), and specifically obtained by polymerizing a monomer containing an alkyl (meth) acrylate. And polymers that can be used. The amorphous polymer may be any of a homopolymer, a random copolymer, a block copolymer, and a graft polymer.

  The amorphous polymer has a glass transition temperature (Tgc) of preferably 5 ° C. or more, more preferably 7 ° C. or more higher than the glass transition temperature (Tga) of the polyvinyl acetal resin. When the glass transition temperature satisfies the above conditions, mechanical properties and heat resistance in a high temperature environment become more sufficient, and the effects of the present invention tend to be sufficiently achieved. In the present specification, the glass transition temperature (Tg) is a sinusoidal frequency of 10 Hz, a measurement temperature of −50 ° C. to 200 ° C., and a temperature increase rate of 3 using a test piece of length 20 mm × width 3 mm × thickness 0.7 mm. This is the peak temperature (Tα) of the loss tangent (tan δ) of the main dispersion when dynamic viscoelasticity measurement is performed under the condition of ° C / min.

  The amorphous polymer preferably has an average degree of polymerization of 100 or more, more preferably from 200 to 5,000, and even more preferably from 200 to 4,000, from the viewpoint of strength characteristics and meltability.

  When the solar cell module of the present invention is required to have high transparency, the refractive index value of the amorphous polymer is preferably close to the refractive index value of the polyvinyl acetal resin serving as the matrix. The method for making the refractive index value of the amorphous polymer close to the refractive index value of the polyvinyl acetal resin as a matrix is not particularly limited. For example, the amorphous polymer to be blended is coated with an outer layer of core-shell type fine particles ( Shell) and the method of controlling the refractive index by selecting the type of component of the inner layer (core) and the like. By setting the refractive index value of the amorphous polymer to a value close to the refractive index value of the polyvinyl acetal resin, high transparency can be exhibited by the sealing material.

The amorphous polymer is preferably a polymer obtained by polymerizing a monomer containing an alkyl (meth) acrylate.
The alkyl methacrylate is preferably an alkyl methacrylate having 1 to 4 carbon atoms in the alkyl group, and specific examples include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, and n-butyl methacrylate. From the viewpoints of physical properties, cost, etc., methyl methacrylate is more preferable.

  The alkyl acrylate is preferably an alkyl acrylate having 1 to 8 carbon atoms in the alkyl group, and specific examples include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, and phenyl acrylate. From the viewpoint of physical properties, cost, etc., methyl acrylate is more preferable.

  An alkyl (meth) acrylate may be used individually by 1 type, and may use 2 or more types together. When using two or more alkyl (meth) acrylates together, when using two or more alkyl methacrylates together, when using two or more alkyl acrylates together, and one or more alkyl methacrylates and one or more alkyl acrylates And when used together.

  The amorphous polymer may be a copolymer obtained by polymerizing alkyl (meth) acrylate and a monomer other than alkyl (meth) acrylate. Examples of monomers other than alkyl (meth) acrylate include ethylenically unsaturated monomers copolymerizable with alkyl (meth) acrylate. Examples of such ethylenically unsaturated monomers include diene compounds such as 1,3-butadiene and isoprene, styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, and styrene nucleus-substituted with halogen. , 1-vinylnaphthalene, 4-methylstyrene, 4-propylstyrene, 4-cyclohexylstyrene, vinyl aromatic compounds such as 4-dodecylstyrene, ethylenically unsaturated nitrile compounds such as acrylonitrile methacrylonitrile, acrylic acid, methacrylic acid Acrylamide, methacrylamide, maleic anhydride, maleic imide, monomethyl maleate, dimethyl maleate and the like. Monomers other than alkyl (meth) acrylate may be used alone or in combination of two or more.

  The mass ratio of the polyvinyl acetal resin and the amorphous polymer is 70:30 to 35:65, preferably 65:35 to 40:60, and more preferably 60:40 to 45:55. When the blending amount of the amorphous polymer is less than 30 parts by weight with respect to 70 parts by weight of the polyvinyl acetal resin, the blending amount of the polyvinyl acetal resin is relatively large, and the physical properties of the resulting sealing material in a high temperature environment In addition, the effect of suppressing water absorption is insufficient. Moreover, when the compounding quantity of an amorphous polymer exceeds 65 mass parts with respect to 35 mass parts of polyvinyl acetal resin, the compounding quantity of polyvinyl acetal resin is relatively too small, and the intensity | strength and toughness of the sealing material obtained are It becomes insufficient.

[Wavelength conversion material]
The wavelength conversion material contained in the sealing material of the present invention is a particle containing an inorganic fluorescent material represented by the formula (I) (hereinafter also simply referred to as an inorganic fluorescent material) and a transparent material. The wavelength converting material may be a particle having a structure in which an inorganic fluorescent substance is included in a transparent material or a particle having a structure in which an inorganic fluorescent substance is supported on a transparent material. The shape of the particles is not particularly limited, but is preferably spherical from the viewpoint of dispersibility in the sealing material. The transparent material is preferably a (meth) acrylic resin. In the present invention, “transparent” means that the transmittance of light having a wavelength of 400 nm to 800 nm at an optical path length of 1 cm is 90% or more.

  When the wavelength conversion material is a particle having a structure in which an inorganic fluorescent material is included in a transparent material, the method for including the inorganic fluorescent material in the transparent fine particles is not particularly limited. For example, there is a method of preparing a mixture by dispersing an inorganic fluorescent substance in a starting material of a transparent material and subjecting the mixture to suspension polymerization. More specifically, by preparing a mixture of an inorganic fluorescent material and a vinyl compound that is a starting material of the transparent material, and polymerizing the starting material using a radical polymerization initiator, the inorganic fluorescent material is contained in the transparent material. Can be made to have a structure in which is included. The inorganic fluorescent substance may be subjected to a surface treatment using a surface treatment agent described later before being dispersed in the starting material of the transparent material. Alternatively, a surface treatment agent may be added to the mixture of the inorganic fluorescent material and the transparent material starting material, and the surface treatment of the inorganic fluorescent material may be performed during suspension polymerization.

  When the wavelength conversion material is a particle having a structure in which an inorganic fluorescent material is supported in a transparent material, the method for supporting the inorganic fluorescent material on the transparent fine particles is not particularly limited. For example, an inorganic fluorescent substance and particles made of a transparent material are mixed with a binder resin and dried.

  The content of the inorganic fluorescent substance in the wavelength conversion material is preferably 0.5% by mass to 1.5% by mass with respect to the mass of the wavelength conversion material, and is 0.7% by mass to 1.2% by mass. It is more preferable. When the content of the inorganic fluorescent material is within this range, the wavelength conversion effect can be ensured at a high level without reducing the transparency of the sealing material.

  The content of the wavelength conversion material in the sealing material is preferably 0.01 parts by mass to 0.5 parts by mass with respect to 100 parts by mass of the resin composition, and 0.05 parts by mass to 0.3 parts by mass. More preferably, it is 0.1 to 0.2 parts by mass.

  The particle diameter of the wavelength conversion material is not particularly limited, but from the viewpoint of improving light utilization efficiency, the volume average particle diameter is preferably 2 μm to 150 μm, more preferably 10 μm to 120 μm, and 50 μm to 120 μm. Is more preferable. In the present invention, the volume average particle diameter of the wavelength conversion material is measured using a laser diffraction method, and corresponds to the particle diameter when the volume integration is 50% in the volume distribution obtained from the particle size distribution curve. The particle size distribution measurement using the laser diffraction method can be performed using a laser diffraction scattering particle size distribution measuring apparatus (for example, product name: LS13320, manufactured by Beckman Coulter).

(Inorganic fluorescent material)
The inorganic fluorescent material used in the present invention is represented by the following formula (I). The inorganic fluorescent material represented by the formula (I) is a green light emitting phosphor having an excitation wavelength band of 300 nm to 450 nm, a fluorescence wavelength of 515 nm, and a sufficiently high emission quantum efficiency of 86%. When this inorganic fluorescent material is irradiated with light from near ultraviolet light to blue light, it is excited to emit light, and wavelength conversion is performed.

_{Ba 1-a Mg 1-b} Al 10 O 17: Eu a, Mn b (I)
(In the formula, a is 0.05 to 0.25, and b is 0.10 to 0.40.)

  The inorganic fluorescent material represented by the formula (I) is more excellent by making the amounts of Eu and Mn (values of a and b) within a specific range among BaMgAlO: Eu and Mn inorganic fluorescent materials. Fluorescence characteristics can be shown. From the viewpoint of emission luminance, excitation wavelength, quantum efficiency, etc., a in formula (I) is more preferably 0.10 to 0.20, and b is more preferably 0.30 to 0.40. When the value of a or b is not less than the above lower limit value, the effect on the emission luminance and the excitation wavelength can be obtained more sufficiently, and when the value of a or b is not more than the above upper limit value, the reduction of the emission luminance is effective. Can be suppressed.

  In the inorganic fluorescent material represented by the formula (I), even if a part of the Ba site of BaMgAlO: Eu, Mn is replaced by any one or two elements selected from the group consisting of Sr and Ca Good.

  An inorganic fluorescent substance can be manufactured with the normal manufacturing method used for manufacture of an inorganic compound. For example, an inorganic fluorescent material having a desired configuration can be manufactured by mixing compounds each containing an element constituting the inorganic fluorescent material at a predetermined ratio, followed by baking treatment. Examples of the compound containing each element include oxides, carbonates, and nitrates.

In the production of the inorganic fluorescent material, a flux may be used as necessary. Examples of the flux include AlF ₃ and BaCl ₂ . When flux is used in the production of the inorganic fluorescent material, one or more halogen elements such as F, Cl, Br, and I may be mixed in a small amount in the inorganic fluorescent material.

  In the production of the inorganic fluorescent material, the content ratio of each atom contained in the inorganic fluorescent material is preferably in the range of −10 mol% to +10 mol% from the desired constituent ratio. When this condition is satisfied, sufficient light emission luminance can be obtained.

  There are no particular restrictions on the conditions for the firing treatment in producing the inorganic fluorescent material, but for example, the temperature can be 1200 ° C. to 1600 ° C., and the time can be 1 hour to 10 hours. Moreover, it is preferable to perform the baking treatment in a reducing atmosphere (for example, a nitrogen-hydrogen reducing atmosphere). The hydrogen concentration in the nitrogen-hydrogen reducing atmosphere is not particularly limited, but can be, for example, 0.5 mass% to 4 mass%.

  The particle diameter of the inorganic fluorescent material is not particularly limited, but the volume average particle diameter is preferably 0.1 μm to 10 μm, preferably 0.2 μm to 5 μm from the viewpoints of light emission luminance, power generation efficiency, incident light scattering, and the like. It is more preferable. In the present invention, the volume average particle diameter of the inorganic fluorescent substance is measured using a laser diffraction method, and corresponds to the particle diameter when the volume integration is 50% in the volume distribution obtained from the particle size distribution curve. The particle size distribution measurement using the laser diffraction method can be performed using a laser diffraction scattering particle size distribution measuring apparatus (for example, product name: LS13320, manufactured by Beckman Coulter). The particle diameter of the inorganic fluorescent material can be adjusted by pulverizing by a conventional method using a pulverizer such as a ball mill, a bead mill, or a jet mill.

  Although the refractive index of the inorganic fluorescent material represented by the formula (I) is not particularly limited, in order to efficiently introduce into the solar cell while suppressing reflection loss of external light entering from any angle to the solar cell. The refractive index of the solar cell element is preferably lower than the refractive index of the SiNx: H layer (also referred to as “cell antireflection film”) and the Si layer. That is, the refractive index of the inorganic fluorescent material represented by the formula (I) is preferably 1.5 to 2.2. Moreover, in order to diffuse the light reflected by the solar cell element out of the incident sunlight and efficiently enter the solar cell element, the refractive index is preferably higher than the refractive index of the transparent material of the wavelength conversion material. That is, the refractive index of the inorganic fluorescent material represented by the formula (I) is preferably 1.6 to 2.1.

  The amount of the inorganic fluorescent material is preferably 0.0001 parts by mass to 0.005 parts by mass, more preferably 0.0005 parts by mass to 0.003 parts by mass with respect to 100 parts by mass of the resin composition. 0.001 part by mass to 0.002 part by mass is more preferable. If the amount of the inorganic fluorescent material is less than 0.0001 parts by mass with respect to the resin composition, a sufficient wavelength conversion effect may not be obtained, and if it exceeds 0.005 parts by mass, sunlight is sufficient for the power generation element. It may be difficult to ensure the transparency required to make the light incident on the light source, and it tends to be disadvantageous in terms of cost.

(Transparent material)
The transparent material used in the present invention is not particularly limited as long as it satisfies the condition that the transmittance of light having a wavelength of 400 to 800 nm at an optical path length of 1 cm is 90% or more. From the viewpoint of light resistance, a (meth) acrylic resin is preferable.

  When the transparent material is a (meth) acrylic resin, the starting material is not particularly limited, and may be selected from vinyl compounds that can be polymerized into a (meth) acrylic resin according to desired characteristics of the wavelength conversion material. it can. Examples of the vinyl compound include (meth) acrylic monomers, vinyl monomers other than (meth) acrylic monomers, (meth) acrylic oligomers, vinyl oligomers other than (meth) acrylic oligomers, and the like. These vinyl compounds may be monofunctional or bifunctional or more. Moreover, these vinyl compounds may be used individually by 1 type, or may use 2 or more types together.

  Examples of (meth) acrylic monomers include (meth) acrylic acid and alkyl esters of (meth) acrylic acid. As (meth) acrylic acid alkyl ester, (meth) acrylic acid unsubstituted alkyl ester such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. , Dicyclopentenyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, urethane (meth) acrylate (for example, reaction product of tolylene diisocyanate and 2-hydroxyethyl (meth) acrylate, A reaction product of trimethylhexamethylene diisocyanate, cyclohexanedimethanol and 2-hydroxyethyl (meth) acrylic acid ester), and a (meth) acrylic acid-substituted alkyl group in which a hydroxyl group, an epoxy group, a halogen group or the like is substituted on these alkyl groups. Tel and the like.

  Examples of vinyl monomers other than (meth) acrylic monomers include (meth) acrylamide, (meth) acrylonitrile, diacetone (meth) acrylamide, styrene, styrene derivatives, vinyl toluene, vinyl toluene derivatives, and the like.

  Examples of vinyl oligomers other than (meth) acrylic oligomers and (meth) acrylic oligomers include oligomers derived from the above-described (meth) acrylic monomers and vinyl monomers other than (meth) acrylic monomers.

  The vinyl compound preferably contains a monofunctional vinyl compound and a bifunctional or higher vinyl compound, and the proportion of the bifunctional or higher vinyl compound is 0.1% by mass to 50% by mass with respect to the total mass of the vinyl compound. %, Preferably 0.5% by mass to 10% by mass.

  Examples of the bifunctional or higher vinyl compound include compounds obtained by reacting a polyhydric alcohol with an α, β-unsaturated carboxylic acid. Specifically, polyethylene glycol di (meth) acrylate (having 2 to 14 ethylene groups), ethylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate , Trimethylolpropane ethoxytri (meth) acrylate, trimethylolpropane propoxytri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, polypropylene glycol di (meth) acrylate (propylene group 2 to 14), dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, bisphenol A polyoxyethylene di (meth) Acrylate, bisphenol A dioxyethylene di (meth) acrylate, bisphenol A trioxyethylene di (meth) acrylate, and bisphenol A deca oxyethylene di (meth) acrylate.

  Other examples of the bifunctional or higher vinyl compound include compounds obtained by adding an α, β-unsaturated carboxylic acid to a polyvalent glycidyl group-containing compound (trimethylolpropane triglycidyl ether triacrylate, bisphenol A diglycidyl ether). Diacrylate and the like), and esterified products of polyvalent carboxylic acids (phthalic anhydride and the like) and substances having a hydroxyl group and an ethylenically unsaturated group (such as β-hydroxyethyl (meth) acrylate).

  The kind of vinyl compound can be selected according to the use, characteristics, etc. of the wavelength conversion material to be formed, and preferably contains at least one selected from the group consisting of alkyl acrylates and alkyl methacrylates.

  The vinyl compound preferably contains at least one vinyl compound having a viscosity at 25 ° C. of 5 mPa · s to 30 mPa · s, preferably 8 mPa · s to 20 mPa · s. Furthermore, the proportion of the vinyl compound having a viscosity at 25 ° C. of 5 mPa · s to 30 mPa · s, preferably 8 mPa · s to 20 mPa · s, is preferably 10% by mass or more based on the mass of the entire vinyl compound, More preferably, it is 20 mass%-50 mass%. Thereby, the dispersibility of the inorganic fluorescent substance in the wavelength conversion material becomes better, and a more excellent wavelength conversion effect is exhibited.

  The vinyl compound as a whole has a viscosity at 25 ° C. of 5 to 30 mPa · s, preferably 8 to 20 mPa · s. When the viscosity is 5 mPa · s or more, even when the density difference between the vinyl compound and the inorganic fluorescent material is large, it is easy to maintain the state in which the inorganic fluorescent material is dispersed in the suspension. As a result, it is contained in the particles. It becomes easy to increase the amount of inorganic fluorescent material to be produced and to control the amount. Conversely, when the viscosity is 30 mPa · s or less, the particle diameter can be easily controlled during suspension polymerization.

  Examples of the vinyl compound having a viscosity at 25 ° C. of 5 mPa · s to 30 mPa · s include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, cyclohexyl methacrylate, dicyclopentenyl methacrylate, Examples include dicyclopentenyloxyethyl methacrylate, pentamethylpiperidyl methacrylate, ethylene glycol dimethacrylate, and dicyclopentenyl acrylate.

  When a plurality of vinyl compounds are used, a plurality of vinyl compounds having a viscosity at 25 ° C. of 5 mPa · s to 30 mPa · s may be used, and a vinyl compound having a viscosity at 25 ° C. of 5 mPa · s to 30 mPa · s; A vinyl compound having a viscosity at 5 ° C. of less than 5 mPa · s may be used in combination.

  As a method for measuring the viscosity of a vinyl compound, a rotational viscometer (single cylindrical rotational viscometer, conical plate rotational viscometer, coaxial double cylindrical rotational viscometer, etc.), capillary viscometer, falling ball viscometer And a cup viscometer. The value of the viscosity used in the present invention is a value measured using a single cylindrical rotational viscometer or a conical plate rotational viscometer as a rotational viscometer, and since it can be measured in a small amount, a conical plate rotational viscometer ( It is preferable to measure using a cone plate type.

(Radical polymerization initiator)
When a vinyl compound is used as a starting material for the transparent material, it is preferable to use a radical polymerization initiator to polymerize the vinyl compound. The radical polymerization initiator is not particularly limited, and a commonly used radical polymerization initiator can be used. For example, a peroxide etc. are mentioned preferably. Specifically, organic peroxides that generate free radicals by heat, azo radical initiators, and the like are preferable.

  Examples of organic peroxides include isobutyl peroxide, α, α′bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, di-n-propylperoxydicarbonate, di-s-butylperoxide. Oxydicarbonate, 1,1,3,3-tetramethylbutyl neodecanoate, bis (4-t-butylcyclohexyl) peroxydicarbonate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, di 2-ethoxyethyl peroxydicarbonate, di (ethylhexyl) peroxydicarbonate, t-hexyl neodecanoate, dimethoxybutyl peroxydicarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, t-Butylperoxyneodecane , T-hexylperoxypivalate, 3,5,5-trimethylhexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2- Ethyl hexanoate, succinic peroxide, 2,5-dimethyl-2,5-di (2-ethylhexanoyl) hexane, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t- Hexylperoxy-2-ethylhexanoate, 4-methylbenzoyl peroxide, t-butylperoxy-2-ethylhexanoate, m-toluoylbenzoyl peroxide, benzoyl peroxide, t-butylperoxyisobuty Rate, 1,1-bis (t-butyl) Peroxy) 2-methylcyclohexane, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t -Butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexanone, 2,2-bis (4,4-dibutylperoxycyclohexyl) propane, 1,1- Bis (t-butylperoxy) cyclododecane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy Laurate, 2,5-dimethyl-2,5-di (m-toluoylperoxy) hexane, t-butyl Tilperoxyisopropyl monocarbonate, t-butylperoxy-2-ethylhexyl monocarbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyacetate 2,2-bis (t-butylperoxy) butane, t-butylperoxybenzoate, n-butyl-4,4-bis (t-butylperoxy) valerate, di-t-butylperoxyisophthalate, α, α′bis (t-butylperoxy) diisopropylbenzene, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, t-butylcumyl peroxide, di-t -Butyl peroxide, p-menthane hydroperoxide, 2,5-dimethyl -2,5-di (t-butylperoxy) hexyne, diisopropylbenzene hydroperoxide, t-butyltrimethylsilyl peroxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, t- Hexyl hydroperoxide, t-butyl hydroperoxide, 2,3-dimethyl-2,3-diphenylbutane and the like can be used.

  Examples of the azo radical initiator include azobisisobutyronitrile (AIBN, also known as V-60), 2,2′-azobis (2-methylisobutyronitrile) (also known as V-59), and 2,2 ′. -Azobis (2,4-dimethylvaleronitrile) (alias V-65), dimethyl-2,2'-azobis (isobutyrate) (alias: V-601), 2,2'-azobis (4-methoxy-2, 4-dimethylvaleronitrile) (alias: V-70).

  The amount of radical polymerization initiator used can be appropriately selected according to the type of vinyl compound, the refractive index of the particles to be formed, and the like. For example, it can be used in an amount of 0.01% by mass to 2% by mass with respect to the total amount of the vinyl compound, and is preferably used in an amount of 0.1% by mass to 1% by mass.

(Surface treatment agent)
The inorganic fluorescent material is preferably surface-modified with a surface treatment agent in order to improve the dispersibility of the transparent material in the starting material. The surface modification treatment can be performed by treating (or coating) the inorganic fluorescent material with a surface treatment agent or the like. The surface treatment agent is not particularly limited as long as it can improve the dispersibility of the transparent material of the inorganic phosphor material in the starting material. For example, silica, a coupling agent (titanium coupling agent, silane coupling agent, etc.), polyorganosiloxane, etc. are mentioned. These surface treatment agents may be used alone or in combination of two or more. The surface treatment in the case of using silica as the surface treatment agent includes a surface treatment by a sol-gel method using tetraalkoxysilane (tetra C1-4-alkoxysilane or oligomer thereof such as tetramethoxysilane).

  Examples of silane coupling agents include halogen-containing silane coupling agents (such as 3-chloropropyltrimethoxysilane), epoxy group-containing silane coupling agents (such as 3-glycidyloxypropyltrimethoxysilane), and amino group-containing silane coupling agents. (2-aminoethyltrimethoxysilane, etc.), mercapto group-containing silane coupling agent (3-mercaptopropyltrimethoxysilane, etc.), vinyl group-containing silane coupling agent (vinyltrimethoxysilane, etc.), (meth) acryloyl group-containing Examples thereof include silane coupling agents (2- (meth) acryloxyethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, etc.).

  Examples of the polyorganosiloxane include polydialkylsiloxanes (for example, polydiC1-10-alkylsiloxanes such as polydimethylsiloxane (dimethicone), preferably polydiC1-4-alkylsiloxanes), polyalkylalkenylsiloxanes (for example, polymethylvinylsiloxane). Poly C1-10-alkyl C2-10-alkenyl siloxane), polyalkylaryl siloxane (eg poly C1-10-alkyl C6-20-aryl siloxane such as polymethylphenylsiloxane, preferably poly C1-4 alkyl C6 -10-aryl siloxane), polydiaryl siloxanes (for example, polydiC6-20-aryl siloxanes such as polydiphenyl siloxane), polyalkyl hydrogen siloxanes (for example, polydiphenylsiloxane). Poly (C1-10-alkylhydrogensiloxane) such as limethylhydrogensiloxane), organosiloxane copolymers (for example, dimethylsiloxane-methylvinylsiloxane copolymer, dimethylsiloxane-methylphenylsiloxane copolymer, dimethylsiloxane-methyl) Examples thereof include vinylsiloxane-methylphenylsiloxane copolymer, dimethylsiloxane-methylhydrogensiloxane copolymer (dimethicone / methicone copolymer), and modified polyorganosiloxanes corresponding to these polyorganosiloxanes. Examples of the modified polyorganosiloxane include hydroxyl-modified polyorganosiloxane (eg, terminal silanol polydimethylsiloxane, terminal silanol polymethylphenylsiloxane, terminal hydroxypropyl polydimethylsiloxane, polydimethylhydroxyalkylene oxide methylsiloxane), amino-modified polyorganosiloxane. (For example, terminal dimethylamino polydimethylsiloxane, terminal aminopropyl polydimethylsiloxane, etc.), carboxy-modified polyorganosiloxane (for example, terminal carboxypropyl polydimethylsiloxane, etc.), etc. are mentioned.

  The surface treatment agent is preferably a silane coupling agent, and more preferably a (meth) acryloyl group-containing silane coupling agent such as 3-methacryloxypropyltrimethoxysilane. The proportion of the surface treatment agent is preferably 0.01% by mass to 70% by mass, and preferably 0.1% by mass to 50% by mass with respect to the entire inorganic fluorescent material (surface-treated inorganic fluorescent material). It is more preferable that it is 0.5 mass%-30 mass%.

[Other ingredients]
The sealing material of the present invention may contain additives such as an antioxidant, an ultraviolet absorber, an adhesion improver, an antiblocking agent, a pigment, a dye, and a functional inorganic compound as necessary. Moreover, the sealing material of this invention may contain resin components other than polyvinyl acetal resin (A), a plasticizer (B), and an amorphous polymer (C) in a resin composition. However, from the viewpoint of reliably achieving the effects of the present invention, the total content of the polyvinyl acetal resin (A), the plasticizer (B), and the amorphous polymer (C) in the resin composition is 97% by mass or more. Preferably, it is 98% by mass or more, more preferably 99% by mass or more.

(Antioxidant)
Examples of the antioxidant include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like. Among these, a phenolic antioxidant is preferable, and an alkyl-substituted phenolic antioxidant is more preferable.

  Examples of phenolic antioxidants include 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate and 2,4-di-t-amyl-6. Acrylate compounds such as-(1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl) phenyl acrylate; 2,6-di-t-butyl-4-methylphenol, 2,6-di- t-butyl-4-ethylphenol, octadecyl-3- (3,5-) di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylene-bis (4-methyl-6-t-butylphenol) ), 4,4′-butylidene-bis (4-methyl-6-tert-butylphenol), 4,4′-butylidene-bis (6-tert-butyl-m-cresol), 4,4′-thiobi (3-methyl-6-tert-butylphenol), bis (3-cyclohexyl-2-hydroxy-5-methylphenyl) methane, 3,9-bis (2- (3- (3-tert-butyl-4-hydroxy) -5-methylphenyl) propionyloxy) -1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, 1,1,3-tris (2-methyl-4- Hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate) methane, triethylene glycol bis (3- (3-t-butyl-4-hydroxy-5-methylphenol) ) Alkyl-substituted phenolic compounds such as propionate); 6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bis-octylthio-1,3,5-triazine, 6- (4- Hydroxy-3,5-dimethylanilino) -2,4-bis-octylthio-1,3,5-triazine, 6- (4-hydroxy-3-methyl-5-t-butylanilino) -2,4-bis -Triazine group-containing phenols such as octylthio-1,3,5-triazine, 2-octylthio-4,6-bis- (3,5-di-t-butyl-4-oxyanilino) -1,3,5-triazine Compound etc. are mentioned.

  Examples of phosphorus antioxidants include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2-t-butyl-4) -Methylphenyl) phosphite, tris (cyclohexylphenyl) phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite, 9,10-dihydro-9-oxa-10-phosphat Phenanthrene-10-oxide, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9 , 10-Dihydro-9-oxa-10-phosphafena Monophosphite compounds such as Tren; 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecylphosphite), 4,4′-isopropylidene-bis (phenyl-di-) Alkyl (C12-C15) phosphite), 4,4′-isopropylidene-bis (diphenylmonoalkyl (C12-C15) phosphite), 1,1,3-tris (2-methyl-4-di-tridecyl) And diphosphite compounds such as phosphite-5-tert-butylphenyl) butane and tetrakis (2,4-di-tert-butylphenyl) -4,4′-biphenylene phosphite. Among these, a monophosphite compound is preferable.

  Sulfur antioxidants include dilauryl 3,3′-thiodipropionate, distearyl 3,3′-thiodipropionate, lauryl stearyl 3,3′-thiodipropionate, pentaerythritol-tetrakis- (β -Lauryl-thiopropionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane and the like.

  An antioxidant may be used individually by 1 type, or may use 2 or more types together. When the antioxidant is used, the blending amount is preferably 0.001 to 5 parts by mass, more preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the polyvinyl acetal resin. .

  When adding an antioxidant to the encapsulant, the timing of addition is not particularly limited, but it is preferably added before the step of extruding the encapsulant, and in the production of the polyvinyl acetal resin as a raw material It is more preferable to add an antioxidant. Furthermore, it is preferable to add an antioxidant to the plasticizer as a raw material.

(UV absorber)
Examples of ultraviolet absorbers include 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α′dimethylbenzyl) phenyl] -2H-benzotriazole, 2 -(3,5-di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3 5-di-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- (2 ′ -Hydroxy-5′-t-octylphenyl) benzotriazole UV absorbers such as benzotriazole; 2,2,6,6-tetramethyl-4-piperidyl Benzoate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) -2- (3,5-di-t -Butyl-4-hydroxybenzyl) -2-n-butylmalonate, 4- (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy) -1- (2- (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy) ethyl) hindered amine ultraviolet absorbers such as 2,2,6,6-tetramethylpiperidine; 2,4-di-t-butyl Examples thereof include benzoate ultraviolet absorbers such as phenyl-3,5-di-t-butyl-4-hydroxybenzoate and hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate.

  When adding an ultraviolet absorber to a sealing material, it is preferable to add in the sealing material located in the reverse side (between a solar cell element and a back sheet) of the light-receiving surface of a solar cell element. The addition amount of the ultraviolet absorber is preferably 10 ppm to 50000 ppm, more preferably 100 ppm to 10000 ppm, based on the mass with respect to the polyvinyl acetal resin. An ultraviolet absorber may be used individually by 1 type, or may use 2 or more types together.

(Adhesion improver)
As the adhesion improver, for example, those disclosed in WO03 / 033583A1 can be used. Among these, at least one selected from the group consisting of alkali metal salts and alkaline earth metal salts of organic acids is preferable, and at least one selected from the group consisting of potassium acetate and magnesium acetate is more preferable. The addition amount of the adhesion improver is preferably 1 ppm to 10000 ppm, more preferably 5 ppm to 1000 ppm, and still more preferably 10 ppm to 300 ppm based on the mass with respect to the polyvinyl acetal resin. The optimum addition amount of the adhesion improver varies depending on the kind of the adhesion improver, the place where the solar cell module is used, and the like, but the adhesion of the obtained film to the glass is determined by the Pummel Test (WO03 / 03583A1 etc.), it is generally preferable to adjust to 3-10. When high penetration resistance is required, it is preferably adjusted to be 3 to 6, and when high glass scattering prevention property is required, it is preferably adjusted to be 7 to 10. When high glass scattering prevention property is required, it is also a useful method not to add an adhesion improver.

(Functional inorganic compounds)
Examples of functional inorganic compounds (excluding inorganic fluorescent substances contained in wavelength conversion materials) include light reflecting materials, thermal conductivity improving materials, electrical property improving materials, gas barrier property improving materials, mechanical properties improving materials, and the like. .

(Method for producing sealing material)
The method for producing the sealing material of the present invention is not particularly limited, and a known method is used, but a method for producing using an extruder is suitably used. The temperature during extrusion of the sealing material is preferably 150 ° C to 250 ° C, and more preferably 180 ° C to 230 ° C. When the temperature of the material of the sealing material is 150 ° C. or lower, the decomposition of the polyvinyl acetal resin is suppressed, and the content of the volatile substance can be suppressed low. If the temperature of the sealing material is 250 ° C. or lower, the content of volatile substances can be kept low. In order to efficiently remove volatile substances, it is preferable to reduce the pressure from the vent port of the extruder.

  The sealing material of the present invention is preferably provided with irregularities on the surface in order to improve the deaeration property in the laminating process. A conventionally known method can be used as a method for providing the unevenness. For example, a method of providing a melt fracture structure by adjusting extrusion conditions, a method of imparting an embossed structure to an extruded film, and the like can be mentioned.

  The thickness of the sealing material of the present invention is not particularly limited, but is preferably 0.38 mm to 2.28 mm. When the thickness is greater than 0.38 mm, the space around the solar cell element and the functional unit can be sufficiently filled, and when it is less than 2.28 mm, an increase in the manufacturing cost of the sealing material can be suppressed, Also, the cycle time of the laminating process can be shortened.

  The sealing material of the present invention has a total light transmittance of 85% measured in accordance with JIS K7105 in a state where a 0.7 mm thick test piece is sandwiched between two 1.3 mm thick glass plates. The above is preferable. When the total light transmittance is 85% or more, the conversion efficiency of the solar cell is sufficiently ensured.

  The sealing material of the present invention has a ratio of storage elastic modulus at 25 ° C. (E ′ @ 25 ° C.) to storage elastic modulus at 100 ° C. (E ′ @ 100 ° C.) (E ′ @ 25 ° C./E′@100° C.) Is preferably 75 or less, and more preferably 60 or less. When the said ratio is 75 or less, the fall of the mechanical physical property of the sealing material in a high temperature environment is suppressed more. Here, the storage elastic modulus is a condition of a sinusoidal frequency of 10 Hz, a measurement temperature of −50 ° C. to 200 ° C., and a temperature increase rate of 3 ° C./min, using a test piece of length 20 mm × width 3 mm × thickness 0.7 mm. It is a value when dynamic viscoelasticity measurement is performed.

[Solar cell module]
The solar cell module of this invention has a solar cell element and the sealing material for solar cells of this invention provided in the light-receiving surface side of the said solar cell element. The solar cell module of the present invention only needs to be provided with the sealing material of the present invention at least on the light receiving surface side of the solar cell element, and the present invention even if the sealing material of the present invention is provided on the back surface side. A sealing material different from the sealing material may be provided. The manufacturing method in particular of the solar cell module of this invention is not restrict | limited, It can manufacture by a well-known method.

  The types of solar cell elements used in solar cell modules include not only single crystal or polycrystalline silicon crystal types, but also compound semiconductors using thin film silicon types, thin film amorphous silicon types, CIS, CIGS, CdTe, GaAs, etc. Examples include molds.

  Examples of the structure of the solar cell module when the solar cell element is a crystal type include, for example, between the surface transparent substrate such as glass and the solar cell element, and between the solar cell element and the back glass or the back sheet. Examples include a structure in which a sealing material is inserted and laminated.

  As the structure of the solar cell module when the solar cell element is a thin film type, for example, (1) a chemical vapor deposition method on the surface of a surface-side transparent protective member such as a glass substrate, a polyimide substrate, or a fluororesin-based transparent substrate A structure in which the sealing material of the present invention and the back surface side protective member are laminated and bonded and integrated on the thin film solar cell element layer formed by, etc., (2) formed on the surface of the back surface side protective member A structure in which the sealing material of the present invention and the surface side transparent protective member are laminated and bonded and integrated on the solar cell element; (3) surface side transparent protective member, surface side sealing material, thin film solar cell Examples include a structure in which an element, a back-side sealing film, and a back-side protective member are laminated in this order and bonded and integrated.

  The solar cell module of the present invention may have a transparent conductive film. Examples of the transparent conductive film include ITO (indium-doped tin oxide), ATO (antimony-doped tin oxide), FTO (fluorine-doped tin oxide), tin oxide (SnO2), and zinc oxide (ZnO). These films can be produced by using various known film forming methods.

  The solar cell module of the present invention may have glass. Although there is no restriction | limiting in particular as glass, Float glass, tempered glass, meshed glass, organic glass, etc. can be used. The thickness of the glass is not particularly limited, but is preferably 1 mm to 10 mm, and more preferably 2 mm to 6 mm.

  The solar cell module of the present invention may have a back sheet. Although there is no restriction | limiting in particular as a back seat | sheet, The thing excellent in a weather resistance and low moisture permeability is used preferably. Examples thereof include polyester films, fluororesin films, laminates thereof, and those in which an inorganic compound is laminated.

  In addition, the solar cell module of the present invention can be combined with a known frame, junction box, sealing agent, mounting jig and mount, antireflection film, various facilities using solar heat, rain gutter structure, and the like.

  As a laminating method for obtaining the solar cell module of the present invention, a known method can be adopted. For example, a method using a vacuum laminator device, a method using a vacuum bag, a method using a vacuum ring, a method using a nip roll, and the like can be mentioned. In addition, a method of adding to the autoclave process after provisional pressure bonding can be additionally performed.

  As a laminating method in the case of using a vacuum laminator apparatus, a known apparatus used for manufacturing a solar cell is used, and laminating is performed at a temperature of 100 ° C. to 200 ° C., preferably 130 ° C. to 160 ° C. under a reduced pressure of 1 Pa to 30000 Pa. The method of doing is mentioned. Examples of the laminating method in the case of using a vacuum bag or a vacuum ring include a method of laminating at 130 ° C. to 145 ° C. under a reduced pressure of about 20000 Pa, for example, according to the method described in European Patent No. 1235683.

  As a laminating method in the case of using a nip roll, there is a method in which after the first temporary press-bonding at a temperature not higher than the flow start temperature of the resin composition, the temporary press-bond is performed under a condition close to the flow start temperature. Specifically, for example, the resin composition is heated to 30 ° C. to 70 ° C. with an infrared heater or the like, degassed with a roll, further heated to 50 ° C. to 120 ° C., and then pressure-bonded with the roll to be bonded or temporarily bonded. The method of letting it be mentioned.

  The autoclave process that is additionally performed after the temporary pressure bonding is performed, for example, at a temperature of 130 ° C. to 145 ° C. for about 2 hours under a pressure of about 1 MPa to 1.5 MPa, depending on the thickness and configuration of the solar cell module. Is done.

  The solar cell module of the present invention can be used as a member for windows, walls, roofs, solariums, soundproof walls, show windows, balconies, handrail walls, or as partition glass members for meeting rooms, etc. You can also Since the sealing material of the present invention has excellent heat resistance, high total light transmittance, and other physical properties that maintain excellent physical properties, the sealing material can be used even when the environmental temperature of the solar cell module rises. It is possible to avoid troubles such as fluidization and deformation, and the appearance of the solar cell is hardly impaired. Therefore, the solar cell module which has the outstanding performance using the sealing material of this invention can be provided.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. In the following examples, “%” and “part” mean “% by mass” and “part by mass”, respectively, unless otherwise specified.

<Production Example 1>
A 2 m ³ reactor equipped with a stirrer was charged with 1700 kg of a 7.5% by weight aqueous solution of polyvinyl alcohol (PVA, polymerization degree 1700, saponification degree 99 mol%) and 74.6 kg of butyraldehyde. Cooled down. To this, 160.1 L of hydrochloric acid having a concentration of 20% by mass was added, and butyralization of PVA was started. After 10 minutes from the end of the addition, the temperature was started to rise, the temperature was raised to 65 ° C. over 90 minutes, and the reaction was further carried out for 120 minutes. Then, the resin which precipitated by cooling to room temperature (25 degreeC) was filtered, and it wash | cleaned 10 times with 10 times the amount of ion-exchange water with respect to resin. Thereafter, it was sufficiently neutralized with a 0.3% by mass sodium hydroxide solution, further washed 10 times with 10 times the amount of ion-exchanged water, and dehydrated. Then, it dried and obtained polyvinyl butyral resin (PVB-1).
The degree of acetalization of the obtained PVB-1 was 70 mol%, the vinyl alcohol unit amount was 29.1 mol%, and the vinyl acetate unit amount was 0.9 mol%. The chloride ion concentration was 50 ppm.

  The obtained PVB-1 was hot-pressed at 140 ° C. for 5 minutes to obtain a test piece having a length of 20 mm × width of 3 mm × thickness of 0.7 mm. About this test piece, using a dynamic viscoelasticity measuring apparatus (Rheology Co., Ltd., trade name: FT Rheospectra DVE-V4), a sine frequency of 10 Hz, a measurement temperature of −50 ° C. to 200 ° C., and a rate of temperature increase of 3 ° C. / When the dynamic viscoelasticity measurement was performed at min and the peak temperature (Tga) of the loss tangent (tan δ) of the main dispersion was determined, it was 92 ° C.

<Production Example 2>
In Production Example 1, polyvinyl butyral resin (PVB-2) was obtained in the same manner as in Production Example 1 except that the amount of butyraldehyde was changed to 85.3 kg. The degree of acetalization of PVB-2 was 78 mol%, the amount of vinyl alcohol units was 21.1 mol%, and the amount of vinyl acetate units was 0.9 mol%. The chloride ion concentration was 50 ppm.
When the peak temperature of the loss tangent (tan δ) of the main dispersion was determined in the same manner as in Production Example 1, it was 88 ° C.

  As the amorphous polymer, PMMA-1 (polymethyl methacrylate, manufactured by Kuraray Co., Ltd., trade name: Parapet EH) and PMMA-2 (polymethyl methacrylate, manufactured by Kuraray Co., Ltd., trade name: Parapet HR-L) were used. . PMMA-1 was hot-pressed at 140 ° C. for 5 minutes to obtain a test piece having a length of 20 mm × width of 3 mm × thickness of 0.7 mm. For this test piece, the peak temperature (Tgc) of the loss tangent (tan δ) of the main dispersion was determined in the same manner as in Production Example 1, and found to be 135 ° C. The peak temperature (Tgc) of the loss tangent (tan δ) of the main dispersion was similarly determined for PMMA-2 and found to be 141 ° C.

[Synthesis of inorganic fluorescent materials]
BaCO ₃ , MgCO ₃ , Al ₂ O ₃ , Eu ₂ O ₃ , and MnCO ₃ were used as raw materials for the inorganic fluorescent material. In addition, using the AlF ₃ as a flux. The raw materials were weighed so that the Eu content was 15 mol% and the Mn content was 35 mol%, and dry-mixed in a mortar to obtain a mixture. Next, the mixture was filled in an alumina crucible, and calcination was performed in a tube furnace at 1450 ° C. in an N ₂ —H ₂ reducing atmosphere (H ₂ concentration 2%) for 3 hours. The obtained fired product was loosened to obtain a target green light-emitting fluorescent substance (Ba _0.85 Mg _0.65 Al ₁₀ O ₁₇ : Eu _0.15 , Mn _0.35 ). The obtained inorganic fluorescent material had a volume average diameter of 1.4 μm and a refractive index of 1.77.

[Surface treatment of inorganic fluorescent materials]
5 g of the obtained inorganic fluorescent material was dispersed in 50 g of toluene, and 0.05 g of a silane coupling agent (3-methacryloxypropyltrimethoxysilane, manufactured by Toray Dow Corning Co., Ltd., trade name: SZ6030) was added while stirring. . After stirring at room temperature (25 ° C.) for 1 hour, it was filtered off, and the obtained solid content was heat-treated in an explosion-proof oven set at 110 ° C. for 1 hour, so that 5.05 g of the surface-treated inorganic fluorescent material was obtained. Obtained.

[Production of wavelength conversion material]
1. Production of Wavelength Conversion Material (1) 1 g of surface-treated inorganic fluorescent substance, 65 g of methyl methacrylate (viscosity at 25 ° C .: 0.44 mPa · s), ethylene glycol dimethacrylate (viscosity at 25 ° C .: 2.98 mPa · s) s) 5 g, dicyclopentenyl methacrylate (viscosity at 25 ° C .: 30 g) 30 g, thermal radical initiator 2,2′-azobis (2,4-dimethylvaleronitrile) 0.5 g, Each was weighed and placed in a 200 ml screw tube, and mixed for 1 hour at a rotation speed of 100 min ⁻¹ using a mix rotor to prepare a mixed solution. To a separable flask equipped with a condenser, 500 g of ion exchange water and 59.1 g of a 1.69% by weight polyvinyl alcohol solution as a surfactant were added and stirred. To this, the previously prepared mixed liquid of methyl methacrylate, ethylene glycol dimethacrylate and dicyclopentenyl methacrylate was added and heated to 50 ° C. with stirring blades at a rotation speed of 350 min ⁻¹ for 4 hours. Reaction was performed to obtain a suspension. This suspension was subjected to a laser diffraction / scattering particle size distribution measuring apparatus (Beckman Coulter, trade name: LS13320) using a pump speed of 50%, an inorganic phosphor-containing particle refractive index of 1.5, and a water refractive index of 1.33. As a result, the volume average particle diameter was measured to be 104 μm. The precipitate was separated by filtration, washed with ion-exchanged water, and dried at 60 ° C. to obtain a wavelength conversion material (1). The wavelength conversion material (1) is a particle in which an inorganic fluorescent material is included in a transparent material made of (meth) acrylic resin, and the content of the inorganic fluorescent material is 1 with respect to the mass of the wavelength conversion material (1). % By mass.

2. Production of Wavelength Conversion Material (2) In the above (1), the wavelength conversion material (1) except that 1 g of europium complex Eu (TTA) ₃ Phen, which is an organic fluorescent material, was used instead of 1 g of the surface-treated inorganic fluorescent material. In the same manner as in 1), a solar cell wavelength conversion material was obtained. TTA means 4,4,4-trifluoro-1-thienyl-1,3-butanedione, and Phen means 1,10-phenanthroline.

<Example 1>
PVB-1: 40 parts by mass, triethylene glycol-di (2-ethylhexanoate) (3GO) as plasticizer: 27.5 parts by mass, PMMA-1: 32.5 parts by mass, wavelength conversion material (1) : 0.01 parts by mass of a resin temperature of 200 ° C. using a kneading / extrusion molding evaluation test apparatus (manufactured by Toyo Seiki Co., Ltd., trade name: Labo Plast Mill) and a roller mixer (manufactured by Toyo Seiki Co., Ltd., R60 type) It was melt-kneaded at a rotation speed of 100 min ⁻¹ to obtain a composition for sealing material. Using the obtained composition for encapsulant, hot pressing was performed at 140 ° C. for 5 minutes to prepare a test piece of encapsulant having a length of 200 mm × width of 200 mm × thickness of 0.7 mm. Using this test piece, the total light transmittance, stress at 50% strain and breaking strain, heat resistance, water absorption, creep characteristics, and MFR120 were evaluated by the following methods. The results are shown in Table 1.

[Stress at 50% strain and fracture strain]
Using a precision universal testing machine (manufactured by Shimadzu Corporation, trade name: Autograph AG-5000B), a No. 2 dumbbell (thickness 0.7 mm) described in JIS K7113 is measured at a tensile speed of 5 mm / min according to JIS K7162. did.

[Heat-resistant]
Using a dynamic viscoelasticity measuring apparatus (trade name: FT Rheospectrer DVE-V4, manufactured by Rheology), a test piece having a length of 20 mm, a width of 3 mm, and a thickness of 0.7 mm was measured with a sinusoidal frequency of 10 Hz and a measurement temperature. The storage elastic modulus E ′ was measured under the measurement conditions of 50 ° C. to 200 ° C. and a temperature increase rate of 3 ° C./min. The ratio of the storage elastic modulus at 25 ° C. (E ′ @ 25 ° C.) to the storage elastic modulus at 100 ° C. (E ′ @ 100 ° C.) (E ′ @ 25 ° C./E′@100° C.) (Temperature dependence of film strength).

[Water absorption rate]
Using a test piece having a length of 50 mm, a width of 50 mm, and a thickness of 0.7 mm, which was previously vacuum-dried at 25 ° C. for 1 week and completely removed of water, 23 ° C., 80% RH (desiccator humidity control) and The water absorption rate of the film was measured under conditions of 23 ° C. and water immersion.

[Creep characteristics]
A sample was placed in an oven set at 110 ° C using a test piece of length 30mm x width 10mm x thickness 0.7mm that had been previously vacuum-dried at 25 ° C for 1 week and completely removed water. With a load of 3.14 g applied, the elongation (mm) of the sample after 17 minutes was measured.

[MFR120]
According to DIN 53735, the amount of resin eluted in 10 minutes was measured under the condition of applying a 10 kg load at 120 ° C.

[Total light transmittance]
A laminated glass sample obtained by sandwiching a test piece having a length of 200 mm, a width of 200 mm, and a thickness of 0.7 mm with two glass plates having a thickness of 1.3 mm and holding at 140 ° C. for 90 minutes under reduced pressure. Was prepared. This sample was measured using a haze meter (trade name: NDH5000 type, manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K 7105, and the total light transmittance TL was calculated.

[Measurement of emission intensity]
Measurement of emission intensity for evaluation of deterioration due to ultraviolet rays and deterioration due to heat was performed as follows. Luminescence intensity measurement by holding a test piece of length 50 mm x width 50 mm x thickness 0.7 mm using two glass plates with a thickness of 1.3 mm for 90 minutes at 140 ° C under reduced pressure. Samples were prepared. About this sample, the emission intensity was measured using a spectrophotometer (trade name: F-2700, manufactured by Hitachi High-Technologies Corporation) (measurement conditions were photovoltage: 400 V, excitation side slit: 20 nm, fluorescence side slit: 10 nm, Scan speed: 240 nm / min). The irradiation wavelength was 325 nm for the wavelength conversion material (1) and 365 nm for the wavelength conversion material (2). The function f (x) with the wavelength on the X-axis and the light emission amount on the Y-axis represents a curve from the start wavelength to the end wavelength of the emission peak and a straight line connecting two points X = X0 and X1 on the function f (x) The area of the enclosed region was calculated and used as the emission intensity.

[Deterioration by ultraviolet rays]
About the laminated glass sample produced above, an ultraviolet lamp (Iwasaki Electric Co., Ltd., trade name: Super UV) for irradiating 1000 W / cm ² of ultraviolet light is used as a light source, and the black panel temperature is 63 ° C. The glass samples were placed facing each other at a position of 235 mm and irradiated with ultraviolet rays. The time required until the area of the emission intensity of the laminated glass sample was 30% with respect to the area of the emission intensity of the laminated glass sample before the ultraviolet irradiation was measured.

[Deterioration due to heat]
About the laminated glass sample produced above, it left still in the oven of 120 degreeC environment. The time required for the area of the emission intensity of the laminated glass sample to reach 30% with respect to the area of the emission intensity of the laminated glass sample before the start of the test was measured.

[Production of solar cell module]
On the tempered glass (manufactured by Asahi Glass Co., Ltd.) as a protective glass, the sealing material produced above is placed, and the photovoltaic cell element on which the electromotive force can be taken out is placed on the light receiving surface. Furthermore, a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., trade name: A-4300) was placed as a back surface solar cell sealing material (sealing material prepared above) and a back film. This was laminated using a vacuum laminator under the conditions of a hot plate 140 ° C., a vacuum of 5 minutes, and a pressure of 40 minutes to produce a solar cell module.

<Evaluation of solar cell characteristics>
The solar cell output was measured under the conditions of 1000 W / m ² and 25 ° C. using a solar simulator (manufactured by Mitsunaga Electric Mfg. Co., Ltd.). For the solar cell output, a solar cell module using the sealing material of Reference Example 1 was produced under the same conditions, and the short-circuit current value of this module was set to 100, and the solar cell output was evaluated as an effect of improving the solar cell output of the examples and comparative examples.

<Example 2>
Except having used 0.05 mass part of wavelength conversion materials (1), the composition for sealing materials was prepared like Example 1, the sealing material was produced, and various physical properties were evaluated. The results are shown in Table 1.

<Example 3>
Except having used 0.1 mass part of wavelength conversion materials (1), the composition for sealing materials was prepared like Example 1, the sealing material was produced, and various physical properties were evaluated. The results are shown in Table 1.

<Example 4>
Except having used 0.2 mass part of wavelength conversion materials (1), the composition for sealing materials was prepared like Example 1, the sealing material was produced, and various physical properties were evaluated. The results are shown in Table 1.

<Example 5>
Except having used 0.3 mass part of wavelength conversion materials (1), the composition for sealing materials was prepared like Example 1, the sealing material was produced, and various physical properties were evaluated. The results are shown in Table 1.

<Example 6>
Except having used 0.4 mass part of wavelength conversion materials (1), the composition for sealing materials was prepared like Example 1, the sealing material was produced, and various physical properties were evaluated. The results are shown in Table 1.

<Example 7>
Except having used 0.5 mass part of wavelength conversion materials (1), the composition for sealing materials was prepared like Example 1, the sealing material was produced, and various physical properties were evaluated. The results are shown in Table 1.

<Example 8>
Except having used 0.8 mass part of wavelength conversion materials (1), the composition for sealing materials was prepared like Example 1, the sealing material was produced, and various physical properties were evaluated. The results are shown in Table 1.

<Example 9>
A composition for a sealing material was prepared in the same manner as in Example 1 except that PVB-2 was used instead of PVB-1, and a sealing material was prepared to evaluate various physical properties. The results are shown in Table 1.

<Example 10>
A composition for a sealing material was prepared in the same manner as in Example 1 except that PMMA-2 was used instead of PMMA-1, and a sealing material was prepared to evaluate various physical properties. The results are shown in Table 1.

<Example 11>
A composition for a sealing material was prepared in the same manner as in Example 9 except that PMMA-2 was used instead of PMMA-1, and a sealing material was prepared to evaluate various physical properties. The results are shown in Table 1.

<Reference Example 1>
Except not adding wavelength conversion material (1), it carried out similarly to Example 1, the resin composition was used for sealing materials, the sealing material was produced, and various physical properties were evaluated. The results are shown in Table 1.

<Comparative Example 1>
Except having used 0.001 mass part of wavelength conversion materials (1), the composition for sealing materials was prepared like Example 1, the sealing material was produced, and various physical properties were evaluated. The results are shown in Table 1.

<Comparative Example 2>
Except having used 1.0 mass part of wavelength conversion materials (1), the composition for sealing materials was prepared like Example 1, the sealing material was produced, and various physical properties were evaluated. The results are shown in Table 1.

<Comparative Example 3>
Except that the wavelength converting material (2) was used instead of the wavelength converting material (1), a sealing material composition was prepared in the same manner as in Example 1, and the sealing material was prepared to evaluate various physical properties. . The results are shown in Table 1.

<Comparative example 4>
Except that the wavelength converting material (2) was used instead of the wavelength converting material (1), a sealing material composition was prepared in the same manner as in Example 4, and the sealing material was prepared to evaluate various physical properties. . The results are shown in Table 1.

<Comparative Example 5>
PVB-1: 72.5 parts by mass, 3GO: 27.5 parts by mass as a plasticizer, and the same as Example 1 except that the amorphous polymer (C) and the wavelength conversion material (1) were not used The composition for sealing materials was prepared, the sealing material was produced, and various physical properties were evaluated. The results are shown in Table 1.

<Comparative Example 6>
A composition for a sealing material was prepared in the same manner as in Comparative Example 5 except that PVB-2 was used instead of PVB-1, and various physical properties were evaluated by preparing a sealing material. The results are shown in Table 1.

<Comparative Example 7>
Sealed in the same manner as in Example 1 except that PVB-1: 60 parts by mass, 3GO: 40 parts by mass as a plasticizer were used, and the amorphous polymer (C) and the wavelength conversion material (1) were not used. A material composition was prepared, a sealing material was prepared, and various physical properties were evaluated. The results are shown in Table 1.

<Comparative Example 8>

  PVB-2: Sealed in the same manner as in Example 1 except that 85 parts by mass, 3GO: 15 parts by mass as a plasticizer were used, and the amorphous polymer (C) and the wavelength conversion material (1) were not used. A material composition was prepared, a sealing material was prepared, and various physical properties were evaluated. The results are shown in Table 1.

<Comparative Example 9>
PVB-1: 54 parts by mass, 3GO: 27.5 parts by mass as a plasticizer, PMMA-1: 18.5 parts by mass, except that the wavelength conversion material (1) was not used, as in Example 1. The composition for sealing materials was prepared, the sealing material was produced, and various physical properties were evaluated. The results are shown in Table 1.

<Comparative Example 10>
PVB-1: 10 parts by mass, 3GO: 27.5 parts by mass as a plasticizer, PMMA-1: 62.5 parts by mass, and the wavelength conversion material (1) was not used. The composition for sealing materials was prepared, the sealing material was produced, and various physical properties were evaluated. The results are shown in Table 1.

<Comparative Example 11>
A composition for a sealing material was prepared in the same manner as in Comparative Example 9 except that PVB-2 was used instead of PVB-1, and a sealing material was prepared to evaluate various physical properties. The results are shown in Table 1.

<Comparative Example 12>
A sealing material composition was prepared in the same manner as in Comparative Example 10 except that PVB-2 was used instead of PVB-1, and various physical properties were evaluated by preparing a sealing material. The results are shown in Table 1.

  In Table 1, “-” in “UV degradation time” and “heat resistance degradation time” in Reference Example 1 and Comparative Examples 5 to 12 means that the wavelength conversion material is not blended and thus evaluation is not performed.

  As shown in the results of Table 1, the sealing material of the present invention does not contain an amorphous polymer with respect to the polyvinyl acetal resin, or the amount of the amorphous polymer added is 30 with respect to 70 parts by mass of the polyvinyl acetal resin. Compared to the case of less than part by mass, the ratio of the storage elastic modulus at 25 ° C. to the storage elastic modulus at 100 ° C. and the value of water absorption were small, and the mechanical properties in a high temperature environment and the water absorption suppression effect were excellent.

  Further, the sealing material of the present invention is a ratio of the storage elastic modulus at 25 ° C. and the storage elastic modulus at 100 ° C. compared with the case where the blending amount of the amorphous polymer exceeds 65 parts by mass with respect to 35 parts by mass of the polyvinyl acetal resin. Even when the solar cell module rises to a high temperature region, it is possible to avoid the trouble that the sealing material flows or deforms.

  Furthermore, the sealing material of the present invention has a longer UV degradation time than the case where the wavelength conversion material contains an organic fluorescent material, and the effect of improving the power generation efficiency is maintained at a high level for a long time. The solar cell output value was high and the transparency was excellent as compared with the case where it was out of the range of 0.0001 parts by mass to 0.005 parts by mass with respect to 100 parts by mass of the resin composition.

Claims (12)

A resin composition containing a polyvinyl acetal resin (A), a plasticizer (B) and an amorphous polymer (C), and a wavelength conversion material,
The mass ratio ((A) :( C)) of the polyvinyl acetal resin (A) and the amorphous polymer (C) in the resin composition is 70:30 to 35:65,
The wavelength conversion material is a particle containing an inorganic fluorescent material represented by the following formula (I) and a transparent material,
The sealing material for solar cells whose content of the said inorganic fluorescent material is 0.0001 mass part-0.005 mass part with respect to 100 mass parts of said resin compositions.
_{Ba 1-a Mg 1-b} Al 10 O 17: Eu a, Mn b (I)
(In the formula, a is 0.05 to 0.25, and b is 0.10 to 0.40.)   The sealing material for solar cells of Claim 1 whose glass transition temperature (Tgc) of an amorphous polymer (C) is 5 degreeC or more higher than the glass transition temperature (Tga) of polyvinyl acetal resin (A).   The total light transmittance measured according to JIS K7105 in a state in which a test piece having a thickness of 0.7 mm is sandwiched between two glass plates having a thickness of 1.3 mm, is 85% or more. The sealing material for solar cells of Claim 2.   The ratio of the storage elastic modulus at 25 ° C. (E ′ @ 25 ° C.) to the storage elastic modulus at 100 ° C. (E ′ @ 100 ° C.) (E ′ @ 25 ° C./E′@100° C.) is 75 or less. The sealing material for solar cells of any one of Claims 1-3.   The solar cell encapsulation according to any one of claims 1 to 4, wherein the amorphous polymer (C) is a polymer obtained by polymerizing a monomer containing an alkyl (meth) acrylate. Wood.   The solar cell sealing material according to any one of claims 1 to 5, wherein the transparent material is a (meth) acrylic resin.   The average particle diameter of the said wavelength conversion material is a sealing material for solar cells of any one of Claims 1-6 which are 2 micrometers-150 micrometers.   The solar cell sealing material according to any one of claims 1 to 7, wherein the inorganic fluorescent material is surface-treated with a silane coupling agent.   The content of the inorganic fluorescent substance in the wavelength conversion material is 0.5% by mass to 1.5% by mass with respect to the mass of the wavelength conversion material, according to any one of claims 1 to 8. Solar cell encapsulant.   The solar cell sealing material according to any one of claims 1 to 9, wherein the inorganic fluorescent substance has a volume average particle diameter of 0.1 to 10 µm.   The solar cell sealing material according to any one of claims 1 to 10, wherein the inorganic fluorescent material has a refractive index of 1.5 to 2.2. A solar cell element;
The solar cell encapsulant according to any one of claims 1 to 11, provided on the light-receiving surface side of the solar cell element,
A solar cell module.