JP2017025334A - Sealing material composition for solar cell, sealing material layer for solar cell using the same, and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing material composition for a solar cell capable of shortening the time for a lamination process and improving light resistance and moist heat resistance, a sealing material layer for a solar cell using the same, and a solar cell module.SOLUTION: The sealing material composition for a solar cell comprises an ethylenic copolymer, an organic peroxide having a peroxy ester structure represented by general formula (1), and an ultraviolet absorbing compound. The ultraviolet absorbing compound has a wavelength conversion function. (In the formula, each of Rand Rindependently represents an optionally substituted 1-18C alkyl group or an optionally substituted 5-18C aryl group.)SELECTED DRAWING: None

Description

  The present invention relates to a sealing material composition particularly suitable for solar cell applications, a solar cell sealing material layer using the same, and a solar cell module using the sealing material layer.

  In the solar cell module, the power generation cell is enclosed and protected in a sealing sheet made of a resin material. In the laminating step of the solar cell module, the crosslinking reaction proceeds by radicals generated by thermal decomposition of the added organic peroxide while the sealing sheet is melted and pressed by heating. Various blends of organic peroxides and other stabilizers have been studied for the purpose of shortening the laminating time, suppressing bubble generation, and suppressing yellowing during outdoor use.

  For example, Patent Document 1 proposes an organic peroxide having a peroxyketal structure for the purpose of shortening the lamination time and suppressing the generation of bubbles. However, the thermal decomposition temperature for generating the radicals of the organic peroxide is low, and there is a problem in that gelation occurs because radicals are generated in the film forming process at about 110 ° C. If it is going to avoid this gelation problem, since it is necessary to form into a film by heating for a short time at sufficient low temperature, it has a big influence on productivity as a sealing sheet. In particular, according to the examination by the applicants, it has been found that the one-minute half-life temperature is desirably higher than 155 ° C., and when it is performed at a temperature lower than that, the degree of yellowing of the formed sealing sheet Was also found to be high.

  Also, for example, Patent Document 2 proposes mixing a compound having a dialkyl peroxyether structure with a compound having a peroxycarbonate structure and thermocompression bonding for about 15 minutes. However, according to the study by the applicants, under the proposed conditions, the organic peroxide added still remains after the thermocompression bonding in the solar cell modules, and these modules are low in light stability, and yellow due to wet heat. It turned out to be strange. In order to consume these organic peroxides, it is necessary to heat at a high temperature for a sufficient time, and it is difficult to shorten the laminating process.

JP 2011-252127 A Japanese Patent No. 4616388

  In light of such circumstances, an object of the present invention is to provide a solar cell encapsulant composition that can shorten the laminating process in terms of time and can improve light resistance and heat-and-moisture resistance.

  Moreover, this invention aims at providing the sealing material layer for solar cells formed with the said sealing material composition for solar cells, and a solar cell module using the same.

  As a result of intensive studies to solve the above-described problems, the present inventors have found that the above-described object is achieved by a solar cell encapsulant composition shown below, a solar cell encapsulant layer using the same, and a solar cell module. As a result, the present invention has been completed.

（式中、Ｒ_１、Ｒ_２、Ｒ_３およびＲ_４は、それぞれ独立して、置換基を有してもよい炭素数１〜１８のアルキル基、または、置換基を有してもよい炭素数５〜１８のアリール基を示す。） The sealing material composition for solar cells of the present invention comprises an ethylene copolymer and an organic peroxide having a peroxyester structure represented by the following general formula (1) or (2). And

(Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently an alkyl group having 1 to 18 carbon atoms which may have a substituent, or an optionally substituted carbon. Represents an aryl group of formula 5-18.)

  By using the solar cell encapsulant composition of the present invention, it is possible to obtain a solar cell encapsulant layer in which the laminating process is shortened in time and the light resistance and heat-and-moisture resistance are improved. In general, organic peroxides tend to oxidize and degrade surrounding organic substances because they are in a highly oxidized state. For this reason, in the solar cell module, the organic peroxide remaining after the lamination becomes one of the causes of defects such as yellowing. As a result of intensive studies, the present inventors need to select an organic peroxide having a sufficiently low oxidizing power while efficiently thermally decomposing in order to function as a crosslinking agent for an ethylene-based copolymer. I found out. On the other hand, the inventors have a 1 minute half-life temperature of 155 ° C. or higher in order to prevent cross-linking during film formation, and 170 ° C. or lower in order that organic peroxide is sufficiently consumed during thermocompression bonding in the laminating process. It was found that it is desirable. In addition, the inventors have clarified that, in particular, organic peroxides having a peroxyester structure of an alkyl group have a low oxidizing power, and these organic peroxides are used. It turned out that it becomes what was excellent in characteristics, such as yellowing, by using the sealing sheet which was used. Furthermore, by designing and controlling the structure of the alkyl group in a more molecular manner, it was possible to find a one-minute half-life temperature within a desired temperature range.

Further, in the solar cell encapsulant composition of the present invention, R ₁ and R ₃ in the general formula (1) and (2), with an optionally substituted alkyl group having 1 to 18 carbon atoms Preferably there is. By using the organic peroxide, it is possible to obtain a solar cell encapsulant layer that can more easily shorten the laminating process in terms of time and improve light resistance and heat and moisture resistance.

Further, in the solar cell encapsulant composition of the present invention, R ₂ in the general formula (1) is preferably a t- butyl or t- hexyl. By using the organic peroxide, it is possible to obtain a solar cell encapsulant layer that can more easily shorten the laminating process in terms of time and improve light resistance and heat and moisture resistance.

Further, in the solar cell encapsulant composition of the present invention, the R ₄ in the general formula (2) preferably have a substituent group which is an alkyl group having 1 to 18 carbon atoms which may. By using the organic peroxide, it is possible to obtain a solar cell encapsulant layer in which the laminating process is shortened in time and the light resistance and heat and moisture resistance are improved.

  Moreover, in the sealing material composition for solar cells of this invention, it is preferable that 0.01-3 weight part of said organic peroxide is included with respect to 100 weight part of ethylene-type copolymers. By setting it as the said structure, the lamination process can be shortened more reliably in time, and the solar cell sealing material layer which improved light resistance and wet heat resistance can be obtained.

  Moreover, in the solar cell sealing material composition of this invention, it is preferable to contain 0.001-0.5 weight part of antioxidant with respect to 100 weight part of ethylene-type copolymers. By setting it as the said structure, the lamination process can be shortened more reliably in time, and the solar cell sealing material layer which improved light resistance and wet heat resistance can be obtained.

  Moreover, the solar cell sealing material composition of this invention WHEREIN: It is preferable that the said antioxidant has the hydroxy toluene frame | skeleton which may have a substituent. By setting it as the said structure, the lamination process can be shortened more effectively in time, and the solar cell sealing material layer which improved light resistance and wet heat resistance can be obtained.

  Moreover, the sealing material composition for solar cells of this invention may contain an ultraviolet-absorbing compound. By using the ultraviolet absorbing compound, it becomes possible to further suppress ultraviolet ray degradation and impart a wavelength conversion function to the sealing material composition, and the solar cell sealing material layer formed from the composition is more multifunctional. Can be.

  On the other hand, the solar cell encapsulant layer of the present invention is formed using the above encapsulant composition. By forming using the said sealing material composition, it can become the sealing material layer for solar cells which shortened the lamination process temporally compared with the past, and improved light resistance and wet heat resistance.

  Moreover, the solar cell module of this invention is characterized by including the solar cell sealing material layer formed using the said solar cell sealing material composition. Since the said solar cell module has the said solar cell sealing material layer, it becomes a solar cell module which shortened the lamination process temporally compared with the past, and improved light resistance and wet heat resistance.

  In the solar cell module of the present invention, the solar cell is a crystalline silicon solar cell, an amorphous silicon solar cell, a microcrystalline silicon solar cell, a thin film silicon solar cell, a heterojunction solar cell, a multijunction solar cell, a sulfide. It is a cadmium / cadmium telluride solar cell, a CIS thin film solar cell, a CIGS thin film solar cell, a CZTS thin film solar cell, a III-V group solar cell, a dye-sensitized solar cell, or an organic semiconductor solar cell. preferable.

The example of the solar cell module using the sealing material layer for solar cells of this invention is shown. The example of the solar cell module using the sealing material layer for solar cells of this invention is shown. The example of the solar cell module using the sealing material layer for solar cells of this invention is shown.

  Embodiments of the present invention will be described below.

（式中、Ｒ_１、Ｒ_２、Ｒ_３およびＲ_４は、それぞれ独立して、置換基を有してもよい炭素数１〜１８のアルキル基、または、置換基を有してもよい炭素数５〜１８のアリール基を示す。） The sealing material composition for solar cells of the present invention comprises an ethylene copolymer and an organic peroxide having a peroxyester structure represented by the following general formula (1) or (2). And

(Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently an alkyl group having 1 to 18 carbon atoms which may have a substituent, or an optionally substituted carbon. Represents an aryl group of formula 5-18.)

（式中、Ｒ_１、Ｒ_２、Ｒ_３およびＲ_４は、それぞれ独立して、置換基を有してもよい炭素数１〜１８のアルキル基、または、置換基を有してもよい炭素数５〜１８のアリール基を示す。） (Encapsulant composition for solar cell)
The sealing material composition for solar cells of the present invention comprises an ethylene copolymer and an organic peroxide having a peroxyester structure represented by the following general formula (1) or (2). And

(Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently an alkyl group having 1 to 18 carbon atoms which may have a substituent, or an optionally substituted carbon. Represents an aryl group of formula 5-18.)

  As the ethylene copolymer in the present invention, a known ethylene copolymer can be appropriately used. The ethylene-based copolymer in the present invention refers to a polymer containing a monomer having an ethylene structure (carbon-carbon double bond), and a polymer containing only the monomer or a copolymer containing the monomer and a main component. Etc. are included. In the present invention, the ethylene copolymer includes a homopolymer of the monomer. Moreover, the said main component shall mean the case where it contains 50 weight% or more by weight ratio in the said copolymer.

  When synthesizing the ethylene copolymer by a copolymerization reaction, a known polymer synthesis method can be appropriately used. Examples thereof include a method of random copolymerization, graft polymerization, cross polymerization, or block copolymerization of one or more types of monomers (monomers). Examples of the copolymerization reaction include radical polymerization (cation, anion, living, etc.), ionic polymerization, addition polymerization (polyaddition), condensation polymerization (polycondensation), cyclopolymerization, ring-opening polymerization, and the like. . In the copolymerization reaction, synthetic methods such as an organic solvent system, an aqueous solution system, an emulsified state, and a suspended state can be appropriately used.

  Examples of the monomer include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate ( (Meth) acrylic acid alkyl ester, cyclohexyl acrylate, cyclohexyl methacrylate, phenyl acrylate, phenyl methacrylate, benzyl acrylate, benzyl methacrylate, styrene, α-methyl styrene, vinyl toluene, acrylamide, diacetone acrylamide, acrylonitrile, methacrylate Examples include nitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide, and the like. Furthermore, (meth) acrylic acid alkyl ester in which the alkyl group is substituted with a hydroxyl group, an epoxy group, a halogen group, or the like can be given. Moreover, alpha-olefin monomers, such as vinyl acetate, 1-hexene, 1-octene, etc. can be mention | raise | lifted. Moreover, in the said (meth) acrylic acid ester, it is preferable that carbon number of the alkyl group of an ester site | part is 1-18, and it is more preferable that it is C1-C8. Of these, the vinyl acetate and α-olefin monomers are often included as monomer components. These compounds may be used alone or in combination of two or more.

  Moreover, when performing a copolymerization reaction, in the said ethylene-type copolymer, a fluorescent pigment compound can be copolymerized and the function of a ultraviolet-ray absorption effect | action or a wavelength conversion effect | action can be provided to a sealing material layer. In this case, the copolymer composition of the fluorescent dye compound can be 0.01 to 20% by weight, 0.02 to 15 parts by weight, 0.05 to 10 parts by weight, or 0 .08 to 6 parts by weight or 0.1 to 4 parts by weight may be used. By setting it as the said range, the wavelength conversion function by a fluorescent pigment compound, shortening of process time, shaping | molding, processing, and durability after shaping | molding can be made to coexist in good balance.

In the ethylene copolymer, the number average molecular weight (Mn) of the ethylene copolymer may be 3 × 10 ^{3 to} 3 × 10 ^6, and is 1 × 10 ⁴ to 1 × 10 ⁶ . There may be 2 * 10 < ⁴ > -5 * 10 < ⁵ >, and 4 * 10 < ⁴ > -2 * 10 < ⁵ > may be sufficient. In addition, the said number average molecular weight uses what was measured by GPC as a reference | standard (polystyrene conversion). By setting it as the above range, molding and processing are easy, and it is preferable for durability after molding.

Moreover, the said ethylene-type copolymer WHEREIN: The weight average molecular weight of the said ethylene-type copolymer can be made into 1 * 10 < ⁴ > -9 * 10 < ⁶ >, Even if it is 2 * 10 < ⁴ > -2 * 10 < ⁶ >. It may be 5 × 10 ⁴ to 1 × 10 ⁶ or 1 × 10 ⁵ to 8 × 10 ⁵ . In addition, the said weight average molecular weight is based on what was measured by GPC (polystyrene conversion). By setting it as the above range, molding and processing are easy, and it is preferable for durability after molding.

  In the ethylene copolymer, the melting temperature (Tm) of the ethylene copolymer is preferably 50 ° C to 130 ° C, may be 55 ° C to 120 ° C, and may be 60 ° C to 110 ° C. ° C may be sufficient and 65 ° C-100 ° C may be sufficient. In addition, the said melting temperature (Tm) (degreeC) shall be measured with the differential scanning calorimeter (DSC). By setting it as the above range, molding and processing are easy, and it is preferable for durability after molding.

  Moreover, when performing a copolymerization reaction, it can superpose | polymerize by adding a thermal polymerization initiator or a photoinitiator to a monomer component (monomer component), for example, and heating or light irradiation.

  A known peroxide can be appropriately used as the thermal polymerization initiator. Examples of the polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane-3, and di-t. -Butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, dicumyl peroxide, α, α'-bis (t-butylperoxyisopropyl) benzene N-butyl-4,4-bis (t-butylperoxy) butane, 2,2-bis (t-butylperoxy) butane, 1,1-bis (t-butylperoxy) cyclohexane, 1,1 -Bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, t-butylperoxybenzate, benzoyl peroxide, etc. . These compounds may be used alone or in combination of two or more.

  The blending amount of the thermal polymerization initiator can be 0.1 to 5 parts by weight with respect to 100 parts by weight of the monomer component, for example.

  As said photoinitiator, the well-known photoinitiator which produces | generates a free radical by an ultraviolet-ray or visible light can be used suitably. Examples of the photopolymerization initiator include benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, and benzoin phenyl ether, benzophenone, N, N′-tetramethyl-4,4′-diamino, and the like. Benzophenones (Michler ketone), benzophenones such as N, N′-tetraethyl-4,4′-diaminobenzophenone, benzyl ketals such as benzyldimethyl ketal (manufactured by Ciba Japan Chemicals, Irgacure 651), benzyl diethyl ketal, 2 , 2-dimethoxy-2-phenylacetophenone, p-tert-butyldichloroacetophenone, acetophenones such as p-dimethylaminoacetophenone, 2,4-dimethylthio Xanthones such as xanthone and 2,4-diisopropylthioxanthone, or hydroxycyclohexyl phenyl ketone (manufactured by Ciba Specialty Chemicals, Irgacure 184), 1- (4-isopropylphenyl) -2-vitoxy-2-methylpropane-1 -On (Ciba Japan Chemicals, Darocur 1116), 2-hydroxy-2-methyl-1-phenylpropan-1-one (Merck, Darocur 1173) and the like can be mentioned. These may be used singly or in combination of two or more.

  Further, as the photopolymerization initiator, for example, a combination of 2,4,5-triallylimidazole dimer and 2-mercaptobenzoxazole, leucocrystal violet, tris (4-diethylamino-2-methylphenyl) methane, etc. Etc. Further, for example, known additives may be used as appropriate, such as tertiary amines such as triethanolamine for benzophenone.

  The blending amount of the photopolymerization initiator can be 0.1 to 5 parts by weight with respect to 100 parts by weight of the monomer component, for example.

  Examples of the ethylene copolymer in the present invention include ethylene copolymer containing vinyl acetate and α-olefin, polyethylene terephthalate, poly (meth) acrylate, polyvinyl acetate, polyethylene tetrafluoroethylene, and the like. Moreover, the said ethylene-type copolymer may further copolymerize other components suitably. These ethylene copolymers may be used alone or in combination of two or more.

  Examples of the poly (meth) acrylate include polyacrylate and polymethacrylate, and examples thereof include (meth) acrylic acid ester resins. Examples of the polyolefin resin include polyethylene, polypropylene, and polybutadiene. Examples of the polyvinyl acetate include polyvinyl formal, polyvinyl butyral (PVB resin), and modified PVB.

  As a constituent monomer of the (meth) acrylic ester resin, for example, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate (Meth) acrylic acid alkyl esters such as cyclohexyl acrylate, cyclohexyl methacrylate, phenyl acrylate, phenyl methacrylate, benzyl acrylate, and benzyl methacrylate. Furthermore, (meth) acrylic acid alkyl ester in which the alkyl group is substituted with a hydroxyl group, an epoxy group, a halogen group, or the like can be given. These compounds may be used alone or in combination of two or more.

  In the (meth) acrylic acid ester, the alkyl group in the ester moiety preferably has 1 to 18 carbon atoms, and more preferably 1 to 8 carbon atoms.

  As said (meth) acrylic acid ester resin, it is good also as a copolymer using the unsaturated monomer copolymerizable with these besides (meth) acrylic acid ester.

  Examples of the unsaturated monomer include unsaturated organic acids such as methacrylic acid and acrylic acid, styrene, α-methylstyrene, acrylamide, diacetone acrylamide, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, and cyclohexylmaleimide. I can give you. These unsaturated monomers may be used alone or in admixture of two or more.

  Among the above (meth) acrylic acid esters, among them, methyl acrylate, ethyl acrylate, isobutyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, It is preferable to use 2-ethylhexyl methacrylate and its functional group-substituted (meth) acrylic acid alkyl ester. From the viewpoint of durability and versatility, methyl methacrylate is a more preferred example.

  The copolymer preferably contains at least one of α-olefin such as 1-hexene and 1-octene or vinyl acetate as a monomer component. It is also preferable to use both α-olefin and vinyl acetate as monomer components. By having the said structure, it becomes what was excellent in workability, light transmittance, and long-term reliability more reliably.

  Examples of the ethylene copolymer include (meth) acrylic acid ester-styrene copolymer, ethylene-vinyl acetate copolymer, and the like. Of these, ethylene-vinyl acetate copolymer is preferable from the viewpoint of moisture resistance, versatility, and cost, and (meth) acrylic acid ester is preferable from the viewpoint of durability and surface hardness. Further, the combined use of an ethylene-vinyl acetate copolymer and a (meth) acrylic acid ester is preferable from the above viewpoints.

  The ethylene-vinyl acetate copolymer preferably has a vinyl acetate monomer unit content of 10 to 35 parts by weight with respect to 100 parts by weight of the ethylene-vinyl acetate copolymer. More preferably, the above-mentioned content is also preferable from the viewpoint of uniform dispersibility in a matrix resin such as a rare earth complex.

  Moreover, when using the said ethylene-vinyl acetate copolymer, the said ethylene-alpha olefin copolymer, etc. as an optically transparent ethylene-type copolymer, a commercial item can be used suitably. Examples of commercially available ethylene-vinyl acetate copolymers include Ultrasen (manufactured by Tosoh Corporation), Everflex (manufactured by Mitsui DuPont Polychemical Co., Ltd.), Suntec EVA (manufactured by Asahi Kasei Chemicals Corporation), UBE EVA copolymer ( Ube Maruzen Polyethylene Co., Ltd.), Evertate (Sumitomo Chemical Co., Ltd.), Novatec EVA (Nihon Polyethylene Co., Ltd.), Smitate (Sumitomo Chemical Co., Ltd.), Nipoflex (Tosoh Corp.), and the like. Examples of commercially available ethylene-α-olefin copolymers include Engage, Affinity, Infuse (above, manufactured by Dow Chemical Co., Ltd.), Tuffmer (produced by Mitsui Chemicals), Kernel (manufactured by Nippon Polyethylene Co., Ltd.), and the like. be able to.

  In the ethylene copolymer, a crosslinkable monomer may be added to form a resin having a crosslinked structure.

  Examples of the crosslinkable monomer include compounds obtained by reacting α, β-unsaturated carboxylic acid with dicyclopentenyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, and polyhydric alcohol ( For example, polyethylene glycol di (meth) acrylate (having 2 to 14 ethylene groups), trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, Trimethylolpropane propoxytri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, polypropylene glycol di (meth) acrylate (propiol Having 2 to 14 ren groups), 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, bisphenol A decaoxyethylene di (meth) acrylate, etc.), a compound obtained by adding an α, β-unsaturated carboxylic acid to a glycidyl group-containing compound (for example, tri Methylolpropane triglycidyl ether triacrylate, bisphenol A diglycidyl ether diacrylate, etc.), polyvalent carboxylic acid (for example, phthalic anhydride), a substance having a hydroxyl group and an ethylenically unsaturated group (for example, β-hydroxy Roxyethyl (meth) acrylate) esterified product, alkyl ester of acrylic acid or methacrylic acid (for example, (meth) acrylic acid methyl ester, (meth) acrylic acid ethyl ester, (meth) acrylic acid butyl ester, (meth) acrylic Acid 2-ethylhexyl ester), urethane (meth) acrylate (for example, reaction product of tolylene diisocyanate and 2-hydroxyethyl (meth) acrylic acid ester, trimethylhexamethylene diisocyanate, cyclohexanedimethanol and 2-hydroxyethyl (meth) A reaction product with an acrylate ester, etc.). These crosslinkable monomers may be used alone or in admixture of two or more. Of these, trimethylolpropane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and bisphenol A polyoxyethylene dimethacrylate are preferred as the crosslinkable monomer.

  When using an ethylene-based copolymer containing the crosslinkable monomer, for example, a thermal polymerization initiator or a photopolymerization initiator may be added to the crosslinkable monomer, and polymerization or crosslinking may be performed by heating or light irradiation to form a crosslinked structure. it can.

  A known peroxide can be appropriately used as the thermal polymerization initiator. Examples of the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane-3, di- t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, dicumyl peroxide, α, α'-bis (t-butylperoxyisopropyl) Benzene, n-butyl-4,4-bis (t-butylperoxy) butane, 2,2-bis (t-butylperoxy) butane, 1,1-bis (t-butylperoxy) cyclohexane, 1, 1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, t-butylperoxybenzate, benzoyl peroxide, etc. The These compounds may be used alone or in combination of two or more.

  The blending amount of the thermal polymerization initiator can be 0.1 to 5 parts by weight with respect to 100 parts by weight of the ethylene copolymer, for example.

  As said photoinitiator, the well-known photoinitiator which produces | generates a free radical by an ultraviolet-ray or visible light can be used suitably. Examples of the photopolymerization initiator include benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isobutyl ether, and benzoin phenyl ether, benzophenone, N, N′-tetramethyl-4,4′-diamino, and the like. Benzophenones (Michler ketone), benzophenones such as N, N′-tetraethyl-4,4′-diaminobenzophenone, benzyl ketals such as benzyldimethyl ketal (manufactured by Ciba Japan Chemicals, Irgacure 651), benzyl diethyl ketal, 2 , 2-dimethoxy-2-phenylacetophenone, p-tert-butyldichloroacetophenone, acetophenones such as p-dimethylaminoacetophenone, 2,4-dimethylthio Xanthones such as xanthone and 2,4-diisopropylthioxanthone, or hydroxycyclohexyl phenyl ketone (manufactured by Ciba Specialty Chemicals, Irgacure 184), 1- (4-isopropylphenyl) -2-vitoxy-2-methylpropane-1 -On (Ciba Japan Chemicals, Darocur 1116), 2-hydroxy-2-methyl-1-phenylpropan-1-one (Merck, Darocur 1173) and the like can be mentioned. These may be used singly or in combination of two or more.

  Further, as the photopolymerization initiator, for example, a combination of 2,4,5-triallylimidazole dimer and 2-mercaptobenzoxazole, leucocrystal violet, tris (4-diethylamino-2-methylphenyl) methane, etc. Etc. Further, for example, known additives may be used as appropriate, such as tertiary amines such as triethanolamine for benzophenone.

  The compounding quantity of the said photoinitiator can use 0.1-5 weight part with respect to 100 weight part of said ethylene-type copolymers, for example.

  Moreover, the said ethylene-type copolymer can also give the function of an ultraviolet-ray absorption effect | action or a wavelength conversion effect | action to a sealing material layer by copolymerizing a fluorescent pigment compound as a monomer in the said ethylene-type copolymer. In this case, the ethylene copolymer can be a light-emitting ethylene copolymer, and can have a function of converting the wavelength of incident light to a longer wavelength.

  Further, when the fluorescent dye compound is copolymerized, the maximum absorption wavelength of the ethylene copolymer is preferably 300 to 410 nm, 330 to 370 nm, or 340 to 360 nm.

  Moreover, when a fluorescent pigment compound is copolymerized, the maximum fluorescence wavelength of the ethylene copolymer is preferably 400 to 560 nm, may be 405 to 490 nm, and may be 410 to 470 nm.

  Further, when the fluorescent dye compound is copolymerized, the absorbance of the ethylene copolymer is, for example, preferably from 0.5 to 6, more preferably from 0.8 to 4, and from 1 to 3 More preferably. The absorbance is a value calculated according to Lambert-Beer law.

  Moreover, as a refractive index of the said ethylene-type copolymer, it is the range of 1.4-1.7, the range of 1.45-1.65, or the range of 1.45-1.55, for example. In some embodiments, the ethylene-based copolymer has a refractive index of 1.5.

  The encapsulant composition for solar cells of the present invention contains the ethylene copolymer, but the ethylene copolymer may be used as a main component, and other matrix resins may be used as a main component. You may use together so that it may become.

  As the other matrix resin, an optically transparent resin is preferably used. Examples of the matrix resin include polyimide, amorphous polycarbonate, siloxane sol-gel, polyurethane, polystyrene, polyethersulfone, polyarylate, epoxy resin, and silicone resin. These matrix resins may be used alone, or two or more kinds of them may be mixed and used with the ethylene copolymer.

  The sealing material composition can be formed, for example, by mixing or dispersing the ethylene copolymer and the other matrix resin. As the above method, for example, a method of removing the solvent after melt kneading or mixing in a solution (or after further casting) may be used. Moreover, you may use only the said ethylene-type copolymer as a matrix raw material.

  In the solar cell encapsulant composition of the present invention, the ethylene copolymer may be used as a main component, or may be used in combination so that another matrix resin is a main component. For example, when the ethylene-based copolymer is used as a main component, the ethylene-based copolymer may be contained at 50 to 100% by weight, and may be 55 to 95% by weight, It may be 60 to 90% by weight, 75 to 85% by weight, or 70 to 80% by weight. Moreover, when using together so that another matrix resin may become a main component, the said ethylene-type copolymer shall be contained by 0.01-49.9 weight%, for example, 0.1% -45 wt%, 1-40 wt%, 2-35 wt%, 3-30 wt%, 5-25 wt% It may be 8 to 20% by weight or 10 to 15% by weight.

（式中、Ｒ_１、Ｒ_２、Ｒ_３およびＲ_４は、それぞれ独立して、置換基を有してもよい炭素数１〜１８のアルキル基、または、置換基を有してもよい炭素数５〜１８のアリール基を示す。） The organic peroxide in the present invention has a peroxyester structure represented by the following general formula (1) or (2).

(Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently an alkyl group having 1 to 18 carbon atoms which may have a substituent, or an optionally substituted carbon. Represents an aryl group of formula 5-18.)

In the organic peroxide, R ₁ , R ₂ , R ₃ and R ₄ each independently have an alkyl group having 1 to 18 carbon atoms which may have a substituent, or have a substituent. Or an aryl group having 5 to 18 carbon atoms. . Although the carbon number of the said alkyl group is 1-18, 2-8 may be sufficient, 3-6 may be sufficient, and 4-5 may be sufficient. The aryl group has 5 to 18 carbon atoms, but may have 6 to 12 or 8 to 10 carbon atoms.

R ₁ , R ₂ , R ₃ and R ₄ are each independently, for example, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, pentyl, hexyl, t-hexyl, heptyl, 2-ethylhexyl, octyl, phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, tetramethylphenyl, ethylphenyl, diethylphenyl, n-propylphenyl, di-n-propylphenyl, isopropylphenyl, diisopropylphenyl, n-butylphenyl, di n-butylphenyl, isopropylphenyl, sec-butylphenyl, disec-butylphenyl, t-butylphenyl, dit-butylphenyl, diisopropylphenyl, naphthyl, biphenyl, phenanthryl, pyrrolyl group, fura Group, thiophenyl group, imidazolyl group, pyrazolyl group, oxazolyl group, thiazolyl group, pyrazinyl group, ethenyl, propenyl, isopropenyl, butenyl, isobutenyl, pentenyl, hexenyl, heptenyl, 2-ethylhexenyl, octenyl, and 3-allyloxy Examples include, but are not limited to, 2-hydroxypropyl and 3-allyloxy-2-acetoxypropyl. R ₁ and R ₂ , R ₃ and R ₄ may be the same or different.

In the above organic peroxide, the general formula (1) and R ₁ and R ₃ (2), it is preferable to have a substituent group which is an alkyl group having 1 to 18 carbon atoms which may.

In the organic peroxide, R _{2 in the} general formula (1) is preferably a t-butyl group or a t-hexyl group.

In the above organic peroxide, wherein R ₄ in the general formula (2) preferably have a substituent group which is an alkyl group having 1 to 18 carbon atoms which may.

  Examples of the organic peroxide having a peroxyester structure represented by the general formula (1) include t-butyl peroxy-acetate, t-hexyl peroxy-acetate, and t-butyl peroxy-n-propion. Acid ester, t-hexyl peroxy-n-propionic acid ester, t-butyl peroxy-2-methylbutanoic acid ester, t-hexyl peroxy-2-methylbutanoic acid ester, t-butyl peroxy-2-methylpentanoic acid ester, t-hexyl peroxy-2-methylpentanoic acid ester, t-butyl peroxy-n-hexanoic acid ester, t-hexyl peroxy-n-hexanoic acid ester, t-butyl peroxy-2-ethylhexanoic acid ester, t-hexyl peroxy-2-ethylhe Sanic acid ester, t-butyl peroxy-3,5,5-trimethylhexanoic acid ester, t-hexyl peroxy-3,5,5-trimethylhexanoic acid ester, t-butyl peroxy-octanoic acid ester, t-hexyl Examples thereof include peroxy-octanoic acid ester, t-butyl peroxy-lauric acid ester, t-hexyl peroxy-lauric acid ester, t-butyl peroxy-stearic acid ester, t-hexyl peroxy-stearic acid ester and the like. These may be used singly or in combination of two or more.

  Examples of the organic peroxide having a peroxyester structure represented by the general formula (2) include 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane, 2,5 -Dimethyl-2,5-di (3,5,5-trimethylhexanoylperoxy) hexane, 2,5-dimethyl-2,5-di (n-octanoylperoxy) hexane, 2,5-dimethyl- Examples thereof include 2,5-di (n-dodecanoylperoxy) hexane, 2,5-dimethyl-2,5-di (n-octadecanoylperoxy) hexane, and the like. These may be used singly or in combination of two or more.

  Further, an organic peroxide having a peroxyester structure represented by the above general formula (2) and an organic peroxide having a peroxyester structure represented by the above general formula (1) are appropriately mixed. May be used.

  Moreover, in the said solar cell sealing material composition, it is preferable that 0.01-3 weight part of the said organic peroxide is included with respect to 100 weight part of ethylene-type copolymers, and 0.03-2 weight part. May be sufficient, 0.05-1.5 weight part may be sufficient and 0.1-1 weight part may be sufficient.

  In the solar cell encapsulant composition, the organic peroxide preferably has a one-minute half-life temperature of 155 ° C. or higher, preferably 158 ° C. or higher, and 160 ° C. or higher. it can. Use of the organic peroxide makes it easy and / or reliable to prevent crosslinking during film formation. Further, the one minute half-life temperature of the organic peroxide is desirably 175 ° C. or lower, can be 172 ° C. or lower, and can be 170 ° C. or lower. By using the organic peroxide, the organic peroxide can be sufficiently consumed at the time of thermocompression bonding in the laminating step. In addition, by using the above organic peroxide, a yellow which is likely to occur in the case of a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a triazine ultraviolet absorber, a salicylic acid ultraviolet absorber, a cyanoacrylate ultraviolet absorber or the like. Changes can be particularly suppressed.

  Moreover, in the solar cell encapsulant composition of the present invention, for example, the encapsulant composition is kneaded at 80 ° C. to 110 ° C. and sheeted at 80 ° C. to 100 ° C. with a hot press or the like, and then the encapsulant is sealed. In the production process of crosslinking the sheet at 155 ° C. to 165 ° C. with a crosslinking time of 15 minutes or less, the use of the organic peroxide particularly effectively shortens the laminating process in terms of time, and improves light resistance and moisture and heat resistance. It becomes possible to improve. The kneading temperature may be 80 ° C to 130 ° C, 90 ° C to 100 ° C, or 110 ° C to 120 ° C. The sheeting temperature may be 80 ° C to 130 ° C, 90 ° C to 100 ° C, or 110 ° C to 120 ° C. Moreover, 160 to 180 degreeC may be sufficient as the said crosslinking temperature, 145 to 155 degreeC may be sufficient, and 160 to 170 degreeC may be sufficient. Moreover, it is preferable that the said crosslinking time is 15 minutes or less, 10-15 minutes may be sufficient, 15-20 minutes may be sufficient, and 20-30 minutes may be sufficient.

  Moreover, as said manufacturing process, a sealing material composition is knead | mixed at 90 to 110 degreeC, for example, is formed into a sheet at 70 to 90 degreeC by calendering, and the said sealing sheet is bridge | crosslinked at 150 to 160 degreeC after that. It may be a production process that crosslinks in 18 minutes or less. Further, for example, the encapsulant composition is kneaded at 70 ° C. to 100 ° C. and sheeted at 70 ° C. to 90 ° C. with a hot press or the like, and then the encapsulated sheet is crosslinked at 140 ° C. to 150 ° C. for 15 minutes or less. It may be a production process in which crosslinking is performed. Further, for example, the encapsulant composition is kneaded at 90 ° C. to 110 ° C., formed into a sheet at 70 ° C. to 110 ° C. by T die casting, and then the encapsulating sheet is 160 ° C. to 180 ° C. with a crosslinking time of 15 minutes or less The manufacturing process which bridge | crosslinks may be sufficient.

  The electronic state of the peroxide bond and the surrounding structure in the organic peroxide affects not only the activation energy for the cleavage of the peroxy structure for radical generation, but also its oxidizing power. In the peroxide bond, it can be said that a peroxide structure or a peroxyester bond having a low electron density has a relatively low oxidizing power. On the other hand, in the film formation of an ethylene copolymer and the crosslinking of a resin composition comprising the same, there is an appropriate temperature range in consideration of its processability. In the present invention, in consideration of the film formation and laminating process of the solar cell encapsulating sheet, the peroxyester bond to which the alkyl group is linked is controlled, and it can be used industrially and is less likely to cause oxidative degradation. A new oxide was discovered and designed.

  Moreover, in the solar cell sealing material composition of this invention, it is preferable that 0.001-0.5 weight part of antioxidant is included with respect to 100 weight part of ethylene-type copolymers, and 0.1-1 Part by weight, 0.01 to 0.05 part by weight, or 0.005 to 0.01 part by weight may be used.

  Moreover, a well-known thing can be used suitably for the said antioxidant. Examples of the antioxidant include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, amine antioxidants, lactone antioxidants, vitamin E antioxidants, and the like. . These compounds may be used alone or in combination of two or more.

  Moreover, the solar cell sealing material composition of this invention WHEREIN: It is preferable that the said antioxidant has the hydroxy toluene frame | skeleton which may have a substituent. Examples of the antioxidant having a hydroxytoluene skeleton that may have the above substituent include a dibutylhydroxytoluene (BHT) derivative.

  Examples of the dibutylhydroxytoluene (BHT) derivative include compounds obtained by chemically modifying a part or a part of the dibutylhydroxytoluene (BHT) in addition to dibutylhydroxytoluene (BHT). Examples of the dibutylhydroxytoluene (BHT) derivative include neutral salts such as sodium salt and potassium salt of dibutylhydroxytoluene, derivatives on the benzene ring or partially substituted alkyl groups, and the like. Of these, dibutylhydroxytoluene (BHT) is preferably used. These may be used singly or in combination of two or more.

  The molecular weight of the dibutylhydroxytoluene (BHT) is 220, but when the dibutylhydroxytoluene (BHT) derivative is used, the molecular weight of the derivative is preferably 220 to 500, and preferably 220 to 400. More preferably, it is 220-300. In addition, molecular weight measurement shall be based on MS spectrum.

  Moreover, the sealing material composition for solar cells of this invention may contain an ultraviolet-absorbing compound. As long as the UV-absorbing compound does not impair the cross-linkability, UV-cutting property, and anti-discoloration function of the solar cell encapsulant layer, the UV-absorbing compound that suppresses the suppression of UV degradation, as well as a wavelength conversion function is provided. An ultraviolet absorbing compound that can be used can be used.

  As the ultraviolet absorbing compound, known compounds can be appropriately used. Examples of the ultraviolet absorbing compound include benzophenone, benzotriazole, triazine, salicylic acid, and cyanoacrylate. These compounds may be used alone or in combination of two or more.

  Examples of the benzophenone-based ultraviolet absorbing compound include 2,2′-dihydroxy-4,4′-di (hydroxymethyl) benzophenone and 2,2′-dihydroxy-4,4′-di (2-hydroxyethyl) benzophenone. 2,2′-dihydroxy-3,3′-dimethoxy-5,5′-di (hydroxymethyl) benzophenone, 2,2′-dihydroxy-3,3′-dimethoxy-5,5′-di (2- Hydroxyethyl) benzophenone, 2,2′-dihydroxy-3,3′-di (hydroxymethyl) -5,5′-dimethoxybenzophenone, 2,2′-dihydroxy-3,3′-di (2-hydroxyethyl) -5,5'-dimethoxybenzophenone, 2,2-dihydroxy-4,4-dimethoxybenzophenone and the like can be mentioned.

  Examples of the benzotriazole ultraviolet absorbing compound include 2- [2′-hydroxy-5 ′-(hydroxymethyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(2-hydroxy). Ethyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-5 ′-(3-hydroxypropyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-3′-methyl-5 ′ -(Hydroxymethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-3'-methyl-5 '-(2-hydroxyethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy -3'-methyl-5 '-(3-hydroxypropyl) phenyl] -2H-benzotriazole, 2- [2'-hydride Xy-3'-t-butyl-5 '-(hydroxymethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-3'-t-butyl-5'-(2-hydroxyethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-3'-t-butyl-5 '-(2-hydroxyethyl) phenyl] -5-chloro-2H-benzotriazole, 2- [2'-hydroxy- 3′-t-butyl-5 ′-(3-hydroxypropyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-3′-t-octyl-5 ′-(hydroxymethyl) phenyl] -2H -Benzotriazole, 2- [2'-hydroxy-3'-t-octyl-5 '-(2-hydroxyethyl) phenyl] -2H-benzotriazole, 2- [2'- Droxy-3′-t-octyl-5 ′-(3-hydroxypropyl) phenyl] -2H-benzotriazole or the like, or 2,2′-methylenebis [6- (2H-benzotriazoly-2-yl) -4- ( Hydroxymethyl) phenol], 2,2'-methylenebis [6- (2H-benzotriazoly-2-yl) -4- (2-hydroxyethyl) phenol], 2,2'-methylenebis [6- (5-chloro- 2H-benzotriazoly-2-yl) -4- (2-hydroxyethyl) phenol], 2,2′-methylenebis [6- (5-bromo-2H-benzotriazoly-2-yl) -4- (2-hydroxyethyl) ) Phenol], 2,2'-methylenebis [6- (2H-benzotriazoly-2-yl) -4- (3-hydroxypropyl) pheno 2,2′-methylenebis [6- (5-chloro-2H-benzotriazoly-2-yl) -4- (3-hydroxypropyl) phenol], 2,2′-methylenebis [6- (5-bromo) -2H-benzotriazoly-2-yl) -4- (3-hydroxypropyl) phenol], 2,2'-methylenebis [6- (2H-benzotriazoly-2-yl) -4- (4-hydroxybutyl) phenol] 2,2′-methylenebis [6- (5-chloro-2H-benzotriazoly-2-yl) -4- (4-hydroxybutyl) phenol], 2,2′-methylenebis [6- (5-bromo-2H -Benzotriazoly-2-yl) -4- (4-hydroxybutyl) phenol], 3,3- {2,2'-bis [6- (2H-benzotriazoly-2-yl)- -Hydroxy-4- (2-hydroxyethyl) phenyl]} propane, 2,2- {2,2'-bis [6- (2H-benzotriazoli-2-yl) -1-hydroxy-4- (2-hydroxy) Ethyl) phenyl]} butane, 2,2′-oxybis [6- (2H-benzotriazoly-2-yl) -4- (2-hydroxyethyl) phenol], 2,2′-bis [6- (2H-benzotriazolyl) -2-yl) -4- (2-hydroxyethyl) phenol] sulfide, 2,2′-bis [6- (2H-benzotriazoly-2-yl) -4- (2-hydroxyethyl) phenol] sulfoxide, 2 2,2'-bis [6- (2H-benzotriazoly-2-yl) -4- (2-hydroxyethyl) phenol] sulfone, 2,2'-bis [6- (2H-ben Toriazori 2-yl), etc. -4- (2-hydroxyethyl) phenol] amine can be exemplified.

  Examples of the triazine-based ultraviolet absorbing compound include 2- (2-hydroxy-4-hydroxymethylphenyl) -4,6-diphenyl-s-triazine and 2- (2-hydroxy-4-hydroxymethylphenyl) -4. , 6-Bis (2,4-dimethylphenyl) -s-triazine, 2- [2-hydroxy-4- (2-hydroxyethyl) phenyl] -4,6-diphenyl-s-triazine, 2- [2- Hydroxy-4- (2-hydroxyethyl) phenyl] -4,6-bis (2,4-dimethylphenyl) -s-triazine, 2- [2-hydroxy-4- (2-hydroxyethoxy) phenyl] -4 , 6-Diphenyl-s-triazine, 2- [2-hydroxy-4- (2-hydroxyethoxy) phenyl] -4,6-bis (2,4-dimethyl) Enyl) -s-triazine, 2- [2-hydroxy-4- (3-hydroxypropyl) phenyl] -4,6-diphenyl-s-triazine, 2- [2-hydroxy-4- (3-hydroxypropyl) Phenyl] -4,6-bis (2,4-dimethylphenyl) -s-triazine, 2- [2-hydroxy-4- (3-hydroxypropoxy) phenyl] -4,6-diphenyl-s-triazine, 2 -[2-hydroxy-4- (3-hydroxypropoxy) phenyl] -4,6-bis (2,4-dimethylphenyl) -s-triazine, 2- [2-hydroxy-4- (4-hydroxybutyl) Phenyl] -4,6-diphenyl-s-triazine, 2- [2-hydroxy-4- (4-hydroxybutyl) phenyl] -4,6-bis (2,4-dimethyl) Enyl) -s-triazine, 2- [2-hydroxy-4- (4-hydroxybutoxy) phenyl] -4,6-diphenyl-s-triazine, 2- [2-hydroxy-4- (4-hydroxybutoxy) Phenyl] -4,6-bis (2,4-dimethylphenyl) -s-triazine, 2- (2-hydroxy-4-hydroxymethylphenyl) -4,6-bis (2-hydroxy-4-methylphenyl) -S-triazine, 2- [2-hydroxy-4- (2-hydroxyethyl) phenyl] -4,6-bis (2-hydroxy-4-methylphenyl) -s-triazine, 2- [2-hydroxy- 4- (2-hydroxyethoxy) phenyl] -4,6-bis (2-hydroxy-4-methylphenyl) -s-triazine, 2- [2-hydroxy-4- (3-H Droxypropyl) phenyl] -4,6-bis (2-hydroxy-4-methylphenyl) -s-triazine, 2- [2-hydroxy-4- (3-hydroxypropoxy) phenyl] -4,6-bis (2-hydroxy-4-methylphenyl) -s-triazine, 2- [4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl] -5- (octyloxy) Examples thereof include phenol and 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol.

  Examples of the salicylic acid-based ultraviolet absorbing compound include phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, and the like.

  Examples of the cyanoacrylate-based ultraviolet absorbing compound include 2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate, ethyl-2-cyano-3,3'-diphenyl acrylate, and the like.

  Moreover, when using what has a wavelength conversion function to the said ultraviolet absorption compound, the fluorescent compound which absorbs more light of the wavelength range 350-400 nm than the light of the wavelength range exceeding 400 nm as the said ultraviolet absorption compound is mention | raise | lifted, for example. be able to. Examples of the fluorescent compound include organic fluorescent compounds and inorganic fluorescent compounds.

  As the organic fluorescent compound, a known organic coloring compound (such as an organic fluorescent dye) can be used. Examples of the organic fluorescent compound include naphthalimide, perylene, anthraquinone, coumarin, benzocoumarin, xanthene, phenoxazine, benzo [a] phenoxazine, benzo [b] phenoxazine, benzo [c] phenoxazine, and naphthalimide. , Naphtholactam, azlactone, methine, oxazine, thiazine, diketopyrrolopyrrole, quinacridone, benzoxanthene, thioepiindrin, lactamimide, diphenylmaleimide, acetoacetamide, imidazothiazine, benzanthrone, perylenemonoimide, phthalimide, benzotriazole Benzothiadiazole, benzoxazole, pyrimidine, pyrazine, triazole, dibenzofuran, triazine, harbituric acid derivatives, etc. It can be. These compounds may be used alone or in combination of two or more.

  Examples of the inorganic fluorescent compound include complex compounds having europium or samarium as the emission center. These compounds may be used alone or in combination of two or more.

  The absorbance of the fluorescent compound is, for example, preferably from 0.1 to 6, more preferably from 0.5 to 4, and even more preferably from 0.8 to 3.

  The ultraviolet absorbing compound preferably has a maximum absorption wavelength in the range of 200 to 400 nm, particularly 280 to 380 nm. Among the ultraviolet rays contained in the irradiated light, particularly ultraviolet rays that may cause photodegradation of ethylene-based copolymers such as ethylene-vinyl acetate copolymer and organic materials such as backsheets by using the above-described ultraviolet absorbing compound. Can be absorbed more effectively. In addition, the maximum absorption wavelength of the said ultraviolet absorption compound can be measured using a commercially available ultraviolet ray measuring apparatus etc. using a well-known method.

  Among the above UV absorbing compounds, for example, from the viewpoint of preventing photodegradation of organic materials such as ethylene copolymers and backsheets, it is preferable to use benzophenone UV absorbing compounds. It is particularly preferable to use a benzophenone-based ultraviolet absorbing compound containing two or less. Examples of the ultraviolet absorbing compound include 2-hydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, and 2-hydroxy-4-n-octoxy-benzophenone. The said compound has the maximum absorption wavelength in the range of 320-350 nm, and can suppress the photodegradation of an ethylene-vinyl acetate copolymer more effectively.

  The content of the ultraviolet absorbing compound is preferably 0.01 to 2 parts by weight, preferably 0.05 to 1 part by weight, based on 100 parts by weight of the ethylene copolymer. It can be -0.5 weight part.

  In addition, as the ultraviolet absorbing compound, for example, a fluorescent dye compound in which a carbon-carbon double bond group is provided in the ultraviolet absorbing compound is used as a monomer during polymerization of an ethylene copolymer or after polymerization. A polymerized light-emitting ethylene copolymer resin may be used.

  Moreover, in the said solar cell sealing material composition, a well-known additive can be suitably contained in the range which does not impair desired performance. Examples of the additive include thermoplastic polymers, light stabilizers, organic peroxides, fillers, plasticizers, silane coupling agents, acid acceptors, and clays. These may be used singly or in combination of two or more.

  As the light stabilizer, known compounds can be appropriately used, and examples thereof include compounds having a function of capturing radical species harmful to the polymer and preventing generation of new radicals. Examples of the light stabilizer include hindered amine light stabilizers (HALS). Examples of the hindered amine light stabilizer include those having a low molecular weight, a high molecular weight, an N-alkyl type, and an NH type. These compounds may be used alone or in combination of two or more. By including the light stabilizer, it is possible to suppress degradation of the matrix resin due to the influence of irradiated light and the like, and yellowing of the solar cell sealing film.

  Examples of the low molecular weight hindered amine light stabilizer include decanedioic acid bis (2,2,6,6-tetramethyl-1 (octyloxy) -4-piperidinyl) ester, 1,1-dimethylethyl hydroper 70% by weight of a reaction product of oxide and octane (molecular weight 737) and 30% by weight of polypropylene; bis (1,2,2,6,6-pentamethyl-4-piperidyl) [[3,5-bis (1 , 1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl malonate (molecular weight 685); bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl-1,2,2, 6,6-pentamethyl-4-piperidyl sebacate mixture (molecular weight 509); bis (2,2,6,6-tetramethyl-4-piperidi ) Sebacate (molecular weight 481); tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate (molecular weight 791); tetrakis (1,2,2, 6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate (molecular weight 847); 2,2,6,6-tetramethyl-4-piperidyl-1,2,3,4 A mixture of butanetetracarboxylate and tridecyl-1,2,3,4-butanetetracarboxylate (molecular weight 900); 1,2,2,6,6-pentamethyl-4-piperidyl-1,2,3,4 Examples thereof include a mixture (molecular weight 900) of butanetetracarboxylate and tridecyl-1,2,3,4-butanetetracarboxylate.

  Examples of the high molecular weight hindered amine light stabilizer include poly [{6- (1,1,3,3-tetramethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2, 2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}] (molecular weight 2,000-3,100); succinic acid Polymer of dimethyl and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (molecular weight 3,100 to 4,000); N, N ′, N ″, N ″ ′-tetrakis- ( 4,6-bis- (butyl- (N-methyl-2,2,6,6-tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10- Diamine (molecular weight 2,286) and A mixture of a polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol; dibutylamine, 1,3,5-triazine, N, N′-bis (2, Polycondensate of 2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine (molecular weight 2,600- 3,400).

  Moreover, as a commercial item of the said hindered amine light stabilizer, for example, LA-52, LA-57, LA-62, LA-63, LA-63p, LA-67, LA-68 (all manufactured by ADEKA), Examples include Tinuvin 744, Tinuvin 770, Tinuvin 765, Tinuvin 123, Tinuvin 144, Tinuvin 622LD, CHIMASSORB 944LD (all manufactured by BASF), and UV-3034 (manufactured by BF Goodrich).

  What is necessary is just to perform according to a well-known method in order to manufacture the said sealing material composition for solar cells. For example, a method of mixing the above materials by a known method using heat kneading, a super mixer (high-speed fluidized mixer), a roll mill, a plast mill, or the like can be given. Moreover, you may perform continuously to manufacture of the said sealing material layer.

(Sealant layer for solar cells)
On the other hand, the solar cell encapsulant layer of the present invention is formed using the above solar cell encapsulant composition. The sealing material layer may have a wavelength conversion function (wavelength conversion type sealing material layer).

  What is necessary is just to perform according to a well-known method in order to manufacture the said sealing material layer. For example, a composition obtained by mixing each of the above materials by a known method using heat kneading, a super mixer (high-speed fluid mixing machine), a roll mill, a plast mill, etc., is subjected to ordinary extrusion molding, calendar molding (calendering), vacuum heat It can be suitably produced by a method of forming a sheet-like material by molding under pressure or the like. Moreover, after forming the said layer on PET film etc., it can manufacture by the method of transcribe | transferring to a surface protective layer. Further, a method of simultaneously kneading and melting and applying with a hot melt applicator can be used.

  More specifically, for example, the sealing material composition containing the ethylene copolymer may be applied as it is to a surface protective layer or a separator, or the material may be applied as a mixed composition with other materials. May be. Moreover, you may form the said sealing material composition by vapor deposition, sputtering, the aerosol deposition method, etc.

  When apply | coating as said mixed composition, it is preferable that melting | fusing point is 50-250 degreeC in consideration of workability, and, as for the said sealing material composition, it is more preferable that it is 50-200 degreeC, and 50-180. More preferably, the temperature is C. For example, when the melting point of the sealing material composition is 50 to 250 ° C., the kneading and melting and application temperature of the composition are preferably performed at a temperature obtained by adding 30 to 100 ° C. to the melting point.

  In some embodiments, the encapsulant layer is produced into a thin film structure by the following steps: (i) The ethylene copolymer (and other matrix resin) powder is in a predetermined ratio. Preparing a polymer solution dissolved in a solvent (for example, tetrachloroethylene (TCE), cyclopentanone, dioxane, etc.); (ii) pouring the polymer solution directly onto a glass substrate; Heat treating from room temperature up to 100 ° C. and completely removing the residual solvent by further vacuum heating at 130 ° C. overnight; and (iii) prior to use, the polymer film in water Peeling and then completely drying the free-standing polymer film; (iv) film thickness, polymer solution concentration and evaporation rate It can be controlled by changing the.

  The thickness of the sealing material layer is preferably 20 to 2000 μm, more preferably 50 to 1000 μm, and still more preferably 100 to 800 μm. When it becomes thinner than 5 μm, the power generation cell may be broken in the laminating process. On the other hand, when it becomes thicker than 700 μm, it is disadvantageous in terms of cost.

  In particular, when providing a wavelength conversion function, the maximum absorption wavelength of the sealing material layer is preferably 300 to 410 nm, 330 to 370 nm, or 340 to 360 nm.

  In particular, when providing a wavelength conversion function, the maximum fluorescence wavelength of the sealing material layer is preferably 400 to 560 nm, may be 405 to 490 nm, and may be 410 to 470 nm.

  Moreover, as a light absorbency of the said sealing material layer, it is preferable that it is 0.5-6, for example, it is more preferable that it is 0.8-4, and it is further more preferable that it is 1-3.

  Moreover, as a refractive index of the said sealing material layer, it is the range of 1.4-1.7, the range of 1.45-1.65, or the range of 1.45-1.55, for example. In some embodiments, the refractive index of the encapsulant composition is 1.5.

(Solar cell module)
The solar cell module 1 according to the present invention includes the sealing material layer 20 and the solar cells 30. 1 and 2 show simple schematic diagrams as an example, but the present invention is not limited to these. Moreover, the sealing material layer 40 and the back sheet | seat 50 can also be suitably provided in the back surface side of the surface protective layer 10 and a photovoltaic cell. Moreover, as long as the said function of the said solar cell sealing material layer is not impaired between these each layers, you may interpose other layers, such as an adhesive material layer and an adhesive layer, suitably. Moreover, you may use the wavelength conversion type sealing material layer containing the said ultraviolet absorption compound suitably as each said sealing material layer.

  Since the said solar cell module is provided with the said sealing material layer, it becomes possible to shorten a lamination process temporally and to improve light resistance and heat-and-moisture resistance. Moreover, when a wavelength conversion type sealing material layer is used, the wavelength which does not normally contribute to photoelectric conversion can be converted into the wavelength which can contribute to photoelectric conversion. Specifically, a certain wavelength can be converted into a longer wavelength, for example, a wavelength shorter than 370 nm can be converted into a wavelength of 370 nm or more. In particular, the wavelength in the ultraviolet region (10 nm to 365 nm) is converted to the wavelength in the visible light region (370 to 800 nm). Moreover, the range of the wavelength which contributes to photoelectric conversion changes with the kind of solar cell, for example, even if it is a silicon-type solar cell, it changes with the crystal | crystallization forms of the silicon used. For example, in the case of an amorphous silicon solar cell, it is considered to be about 400 nm to 700 nm, and in the case of a polycrystalline silicon solar cell, about 600 nm to 1100 nm. For this reason, the wavelength contributing to photoelectric conversion is not necessarily limited to the wavelength in the visible light region.

  Examples of the solar battery cell include a crystalline silicon solar battery, an amorphous silicon solar battery, a microcrystalline silicon solar battery, a thin film silicon solar battery, a heterojunction solar battery, a multijunction solar battery, a cadmium sulfide / cadmium telluride solar battery, A CIS thin film solar cell, a CIGS thin film solar cell, a CZTS thin film solar cell, a III-V group solar cell, a dye-sensitized solar cell, or an organic semiconductor solar cell can be used. The solar battery cell is preferably a crystalline silicon solar battery.

  In the production of the solar cell module, the solar cell encapsulant layer may be transferred to the solar cell or the like, or may be directly coated on the solar cell. Moreover, you may form the said sealing material layer for solar cells, and another layer simultaneously.

  Further, when the wavelength conversion type sealing material layer is used, the solar cell module of the present invention is arranged so that incident light passes through the wavelength conversion type sealing material layer prior to reaching the solar battery cell. It is preferable. By setting it as the said structure, it becomes possible to more reliably convert the spectrum of the wider range of solar energy into electricity, and can improve photoelectric conversion efficiency effectively.

  As the surface protective layer, a known layer used as a surface protective layer for solar cells can be used. Examples of the surface protective layer include a front sheet and glass. As said glass, various things, such as a white board and the presence or absence of embossing, can be used suitably, for example.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below.

(Method for producing sealing sheet)
[Examples 1-6, Comparative Examples 1-3]
0.3 parts by weight of organic peroxide as a crosslinking agent, 0.3 part by weight of silane coupling agent (γ-methacryloxypropyltrimethoxysilane) as a crosslinking agent, and a crosslinking aid (triallyl isocyan) 1 part by weight of nurate), 0.04 part by weight of antioxidant (BHT, dibutylhydroxytoluene), 0.2 part by weight of SS130 or PA680 as an ultraviolet absorber, and 0 of TN765 or TN144 as a hindered amine light stabilizer. .04 parts by weight were blended, kneaded at 110 ° C., and formed into a sheet at 100 ° C. with a hot press to prepare a solar cell encapsulating sheet.

[Comparative Example 4]
0.15 parts by weight of PB-E and 1.5 parts by weight of PH-25B as a crosslinking agent, and 0.3 parts by weight of a silane coupling agent (γ-methacryloxypropyltrimethoxysilane) as a crosslinking agent with respect to a commercially available EVA resin Parts, 1 part by weight of a crosslinking aid (triallyl isocyanurate), 0.04 parts by weight of an antioxidant (BHT, dibutylhydroxytoluene), 0.2 parts by weight of SS130 as a UV absorber, hindered amine light stabilization 0.04 parts by weight of TN144 was blended as an agent, kneaded at 110 ° C., and formed into a sheet at 100 ° C. with a hot press machine to prepare a solar cell encapsulating sheet.

(Evaluation sample preparation method)
The obtained sealing sheet (thickness: 500 um) was sandwiched between two glasses, or between glass and a back sheet, and bonded at 80 ° C. and 100 kN, and then dried in a drying oven at 160 ° C. for 15 minutes. Stored. Thereafter, the photostability and the degree of yellowing were evaluated.

(Evaluation method of light stability)
The double-sided glass sample was irradiated with 1 W / cm ² of UV light (365 nm) for a predetermined time (120 minutes) using a UV irradiator (manufactured by Panasonic, UJ35) and a lens. The absorption spectrum of the sample after UV light irradiation was measured with a spectrophotometer (manufactured by JASCO Corporation, V560). From the obtained spectrum information, the change of the absorption peak top of the organic compound was evaluated.

(Evaluation method of yellowing)
The sample laminated with the glass and the back sheet was stored for 1000 hours in an environmental evaluation tester set at a temperature of 85 ° C. and a relative humidity of 85%. The reflection spectrum of the sample before and after storage was measured by MCPD (manufactured by Otsuka Electronics Co., Ltd.). From the obtained reflection spectrum information, the yellowing degree (YI: Yellow Index, ASTM D1925) was calculated from the difference between before and after storage.

〔Example〕
(Organic peroxide having peroxyester structure)
T-butyl peroxy-3,5,5-trimethylhexylate (manufactured by NOF Corporation, perbutyl 355 (PB-355))
T-butyl peroxy-lauric acid ester (manufactured by NOF Corporation, perbutyl L (PB-L))
T-hexyl peroxy-acetate (manufactured by NOF Corporation, perhexyl A (PH-A))

[Comparative Example]
(Organic peroxides with other structures)
2,5-dimethyl-2,5-di (t-butylperoxy) hexane (manufactured by NOF Corporation, Perhexa 25B (PH-25B))
T-butyl peroxy-2-ethylhexyl-monocarbonate (manufactured by NOF Corporation, perbutyl E (PB-E))
1,1-di (t-hexylperoxy) cyclohexane (manufactured by NOF Corporation, Perhexa HC (PH-HC))

(UV absorber)
2-Hydroxy-4-n-octoxy-benzophenone (Sumitomo Chemical Industries, Sumisorb 130 (SS130))
4,7-bis (4-t-butyl-phenyl) -2-isobutyl-2H-benzotriazole (manufactured by Nitto Denko Corporation, PA680)

(Hindered amine light stabilizer)
-Bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate (tinuvin 765 (TN765))
2-[[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] -2-butylpropanedioic acid bis [1,2,2,6,6-pentamethyl-4-piperidinyl ] (Tinubin 144 (TN144))

DESCRIPTION OF SYMBOLS 1 Solar cell module 10 Surface protective layer 20 Solar cell sealing material layer 30 Solar cell 40 Back surface sealing material layer 50 Back sheet

Claims (11)

It contains an ethylene copolymer, an organic peroxide having a peroxyester structure represented by the following general formula (1), and an ultraviolet absorbing compound, wherein the ultraviolet absorbing compound has a wavelength conversion function. A solar cell encapsulant composition.

(Wherein, R _1, and R ₂ are each independently an alkyl group having 1 to 18 carbon atoms which may have a substituent, or, even better carbon atoms 5 to 18 have substituent Represents an aryl group.) The solar cell encapsulant composition according to claim 1, wherein R _{1 in the} general formula (1) is an alkyl group having 1 to 18 carbon atoms which may have a substituent. The solar cell encapsulant composition according to claim 1, wherein R _{2 in the} general formula (1) is a t-butyl group or a t-hexyl group.   4. The solar cell encapsulant composition according to claim 1, comprising 0.01 to 3 parts by weight of the organic peroxide with respect to 100 parts by weight of the ethylene-based copolymer. .   The solar cell encapsulant composition according to any one of claims 1 to 4, wherein the crosslinking aid is triallyl isocyanurate.   6. The solar cell encapsulant composition according to claim 1, comprising 0.001 to 0.5 parts by weight of an antioxidant with respect to 100 parts by weight of the ethylene-based copolymer. .   The solar cell encapsulant composition according to claim 6, wherein the antioxidant has a hydroxytoluene skeleton which may have a substituent.   The sealing material composition for solar cells in any one of Claims 1-7 containing a hindered amine light stabilizer (HALS).   The solar cell sealing material layer formed with the solar cell sealing material composition in any one of Claims 1-8.   The solar cell module containing the sealing material layer for solar cells of Claim 9, and a photovoltaic cell. The solar cell is a crystalline silicon solar cell, an amorphous silicon solar cell, a microcrystalline silicon solar cell, a thin film silicon solar cell, a heterojunction solar cell, a multijunction solar cell, a cadmium sulfide / cadmium telluride solar cell, or a CIS system. The solar cell module according to claim 10, which is a thin film solar cell, a CIGS thin film solar cell, a CZTS thin film solar cell, a III-V group solar cell, a dye-sensitized solar cell, or an organic semiconductor solar cell.

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