JP5781282B2 - Solar cell sealing film, solar cell module, and manufacturing method thereof - Google Patents

Description

  The present invention relates to a sealing film for a solar cell, a solar cell module, and a manufacturing method thereof.

  The solar cell module is usually formed by laminating solar cells formed of polycrystalline silicon or the like between two solar cell sealing films made of ethylene / vinyl acetate copolymer (EVA), and the like. It has a structure in which both front and back surfaces are covered with a protective sheet (protective member) for a solar cell module. Such a solar cell module is obtained by laminating a surface side transparent protective member, a solar cell sealing film, a solar battery cell, a solar cell sealing film, and a back surface side protective member in this order, and the obtained laminate. Manufactured by heating and pressurizing to cure EVA by cross-linking and sealing.

  In order to cure and cure EVA by heating and pressurizing, a crosslinking agent such as an organic peroxide, and various additives for imparting adhesiveness and long-term durability to solar cells and the like are used as a sealing film for solar cells. It is proposed to add to (for example, refer to Patent Document 1).

  In many crystalline silicon solar cells, a p-type region is formed on either surface of the single-crystal silicon substrate, and an n-type region is formed on the other surface. On the front and back surfaces, collector electrodes (bus bar electrodes, finger electrodes, etc.) for collecting current generated on the light receiving surface (or back surface) are formed. In addition, since the collector electrode arrange | positioned at the light-receiving surface side shields incident light, there existed a case where power generation efficiency was reduced.

  As one solution to increase the effective light receiving area, p-doped regions and n-doped regions are alternately provided on the back side opposite to the light receiving surface of the solar cell, and the charge extraction structure is entirely formed on the back side. (For example, refer to Patent Document 2). The solar cell having such a structure is referred to as a back contact type solar cell.

  In addition, a p / n junction is formed on a substrate provided with a through hole (through hole), and a doped layer on the front surface (light receiving surface) side is formed up to the through hole inner wall and the through hole peripheral portion on the back surface side. A back contact type solar cell that takes out the current of the light receiving surface has also been proposed (see Patent Document 3).

JP 2007-281135 A JP 2006-523025 A Japanese Patent Laid-Open No. 2-51282

  The solar cell sealing film is required to have a high volume resistivity of the cured product in order to prevent a decrease in power generation efficiency due to ion migration and a decrease in power generation efficiency of the solar cell module due to charging. However, the volume specific resistance of the cured product of the solar cell sealing film varies depending on various factors. For example, a light stabilizer or the like is often added to a general solar cell sealing film in order to improve long-term stability. However, by adding a light stabilizer or the like, the volume specific resistance of the cured product of the solar cell sealing film obtained tends to decrease. For this reason, it has been difficult to achieve both improvement in the stability of the solar cell sealing film with respect to light and improvement in power generation efficiency of the solar cell module.

  This invention is made | formed in view of the problem which such a prior art has, and the place made into the subject is that the volume specific resistance of the hardened | cured material which can manufacture a solar cell module with high electric power generation efficiency is high. It is providing the sealing film for solar cells. Moreover, the place made into the subject of this invention is providing the solar cell module with high electric power generation efficiency, and its manufacturing method.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that an ethylene polymer having a water vapor permeability within a predetermined numerical range and a hindered amine-based light stabilizer represented by a specific structural formula ( Coexistence with HALS) has found that the above-mentioned problems can be achieved, and the present invention has been completed.

  That is, according to this invention, the manufacturing method of the sealing film for solar cells, a solar cell module, and a solar cell module shown below is provided.

[1] An ethylene polymer having a water vapor permeability of 0.1 to 1 g · mm / (m ² · 24 h) at 23 ° C. and 90% RH, and a light stabilizer represented by the following general formula (1): And a melt flow rate (MFR) measured at 190 ° C. and a load of 2.16 kg is 0.1 to 100 g / 10 min in accordance with JIS K-7210.

  In the general formula (1), X represents an alkyl group, alkenyl group, alkyloxy group, alkenyloxy group, alkyloxycarbonyl group, alkenyloxycarbonyl group, aryloxycarbonyl group, acyl group, acyloxy group, alkyloxycarbonyloxy. Group, alkenyloxycarbonyloxy group, aryloxycarbonyloxy group, alkylsulfonyl group, alkenylsulfonyl group, arylsulfonyl group, alkylsulfinyl group, alkenylsulfinyl group, arylsulfinyl group, sulfamoyl group, or carbamoyl group, R is A monovalent substituent is shown.

  [2] The solar cell sealing film according to [1], wherein the ethylene polymer is at least one of an ethylene / α-olefin / diene copolymer and an ethylene / α-olefin copolymer.

  [3] The solar cell sealing film according to [1] or [2], wherein the content of the light stabilizer is 0.05 to 1 part by weight with respect to 100 parts by weight of the ethylene polymer.

  [4] The solar cell sealing film according to [1], further including at least one of a crosslinking agent and an adhesion auxiliary agent.

  [5] A front surface side transparent protective member, a back surface side protective member, a plurality of solar cells sandwiched between the front surface side transparent protective member and the back surface side protective member, the front surface side transparent protective member and the back surface side A sealing member that seals the solar battery cell between the protective member, and the sealing member is a cured solar cell sealing film according to any one of [1] to [4]. Solar cell module that is a thing.

  [6] A surface-side transparent protective member, the first solar cell sealing film according to any one of [1] to [4], a solar cell, and any of [1] to [4] A step (i) of forming a laminate by laminating the second solar cell sealing film according to claim 1 and a back surface side protective member in this order; and the laminate obtained in the step (i). And a step (ii) of integrating by heating and pressurizing to produce a solar cell module.

  The sealing film for solar cells of the present invention contains an ethylene polymer having a water vapor transmission rate in a predetermined numerical range and a hindered amine light stabilizer (HALS) represented by a specific structural formula. To do. For this reason, the sealing film for solar cells of the present invention has high volume resistivity of the cured product while having high light stability. Therefore, if the solar cell sealing film of the present invention is used, a solar cell module with high power generation efficiency can be manufactured.

  Hereinafter, the solar cell sealing film, the solar cell module, and the manufacturing method thereof of the present invention will be described in detail. In the following description, a numerical range is defined using “to”, but “to” in this specification includes a boundary value. For example, “10 to 100” means 10 or more and 100 or less.

1. Solar cell sealing film The solar cell sealing film of the present invention has an ethylene polymer having a water vapor transmission rate of 0.1 to 1 g · mm / (m ² · 24 h) at 23 ° C. and 90% RH, And a hindered amine light stabilizer (HALS) represented by a specific structural formula.

(Ethylene polymer)
It is presumed that a water-filled path through which cluster-like water molecules can pass is formed in the ethylene-based polymer (in the resin) whose water vapor permeability is too high. In this case, it is estimated that HALS having a relatively high basicity easily forms hydrogen bonds with water molecules, making it difficult to move through the resin. On the other hand, a resin having a water vapor permeability that is too low forms a fine microstructure, and it is presumed that the above-mentioned path through which cluster-like water molecules can pass is not formed in the resin. In this case, HALS, which has few groups capable of forming hydrogen bonds, has a large molecular weight, and easily forms a bulky conformation, is presumed to be difficult to move freely in a dense microstructure.

The water vapor permeability at 23 ° C. and 90% RH of the ethylene polymer contained in the solar cell sealing film of the present invention is 0.1 to 1 g · mm / (m ² · 24 h), preferably 0. 1 to 0.7 g · mm / (m ² · 24 h). Although the sealing film for solar cells of the present invention contains a light stabilizer, the volume resistivity of the cured product is unlikely to decrease. For this reason, the solar cell sealing film of the present invention has high light stability, and has a property that the cured product has high volume resistivity and is difficult to be charged. In this way, the volume resistivity of the cured product is increased because the water vapor transmission rate of the ethylene polymer as the main material (main polymer component) is in the above numerical range, so that a specific HALS is sealed for solar cells. This is thought to be because it becomes difficult to polarize in the cured product of the stop film, making it difficult to move appropriately.

The water vapor transmission rate of an ethylene polymer at 23 ° C. and 90% RH can be measured according to the “moisture permeable cup method” based on JIS K0208-1976. Further, the water vapor permeability of the ethylene polymer at 40 ° C. and 90% RH is usually 0.1 to 10 g · mm / (m ² · 24 h), preferably 0.1 to 0.7 g · mm / ( m ² · 24h). The water vapor permeability of an ethylene / vinyl acetate copolymer (EVA) conventionally used as a material for a sealing film for solar cells is usually 5 to 7 g · mm / (m ^{2 at} 23 ° C. and 90% RH. It is about 24 h), and is usually about 10 to ²⁰ g · mm / (m ² · 24 h) at 40 ° C. and 90% RH.

  The ethylene-based polymer is a copolymer including a structural unit derived from ethylene and a structural unit derived from a monomer copolymerizable with ethylene. Specific examples of the ethylene polymer include (i) an ethylene / α-olefin / diene copolymer, (ii) an ethylene / α-olefin copolymer, and (iii) an ethylene / cyclic olefin copolymer. Can do. Of these, (i) an ethylene / α-olefin / diene copolymer and (ii) an ethylene / α-olefin copolymer are preferable. These ethylene-based polymers may be random copolymers or block copolymers. Moreover, these ethylene-type polymers can be used individually by 1 type or in combination of 2 or more types.

  (I) Examples of the ethylene / α-olefin / diene copolymer include an ethylene / propylene / diene copolymer (EPDM). Examples of the diene component constituting the ethylene / α-olefin / diene copolymer include 5-ethylidene-2-norbornene, 5-propylidene-5-norbornene, dicyclopentadiene, 5-vinyl-2-norbornene, 5- Cyclic dienes such as methylene-2-norbornene, 5-isopropylidene-2-norbornene, norbornadiene; 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 5-methyl Chain-like non-conjugated dienes such as -1,5-heptadiene, 6-methyl-1,5-heptadiene, 6-methyl-1,7-octadiene, 7-methyl-1,6-octadiene are included. A part of the diene component may be a triene such as 2,3-diisopropylidene-5-norbornene and 4-ethylidene-8-methyl-1,7-nonadiene. Among these, 5-ethylidene-2-norbornene, dicyclopentadiene, and 5-vinyl-2-norbornene are preferable as the diene component from the viewpoint of moldability of the solar cell sealing film.

  The melt flow rate (MFR) of an ethylene / α-olefin / diene copolymer (typically EPDM) at 190 ° C. and a load of 2.16 kg is preferably 0.1 to 50 g / min. More preferably, it is -30 g / min. When the MFR is within the above numerical range, the flexibility of the solar cell sealing film is increased and the workability is enhanced. For this reason, the embedding property of the solar cell element in the solar cell sealing film is improved.

  The diene content of the ethylene / α-olefin / diene copolymer (typically EPDM) is such that the iodine value of the ethylene / α-olefin / diene copolymer is, for example, 0.5 to 50 g / 100 g, preferably It is set to be 10 to 30 g / 100 g. When the diene content is within the above numerical range, the heat resistance and weather resistance of the solar cell sealing film are improved.

  The ethylene content of the ethylene / α-olefin / diene copolymer (typically EPDM) is, for example, 50 to 75% by weight, preferably 50 to 55% by weight. When the ethylene content is within the above numerical range, there is an advantage that the compression set at a low temperature of the solar cell sealing film is reduced.

  (Ii) Specific examples of the ethylene / α-olefin copolymer include a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. The ethylene / α-olefin copolymer may be a copolymer of ethylene and two or more types of α-olefins. The ethylene / α-olefin copolymer may be a modified polymer of an ethylene polymer.

  Specific examples of the α-olefin constituting the ethylene / α-olefin copolymer include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, Examples thereof include 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene and the like. Of these, α-olefins having 4 to 10 carbon atoms are preferable.

(Iii) Specific examples of the cyclic olefin constituting the ethylene / cyclic olefin copolymer include a norbornene derivative, a tricyclo-3-decene derivative, a tricyclo-3-undecene derivative, a tetracyclo-3-dodecene derivative, and a pentacyclo-4-pentadecene. Derivatives, pentacyclopentadecadiene derivatives, pentacyclo-3-pentadecene derivatives, pentacyclo-4-hexadecene derivatives, pentacyclo-3-hexadecene derivatives, hexacyclo-4-heptadecene derivatives, heptacyclo-5-eicosene derivatives, heptacyclo-4-eicosene derivatives Heptacyclo-5-heneicosene derivative, octacyclo-5-docosene derivative, nonacyclo-5-pentacocene derivative, nonacyclo-6-hexacocene derivative, cyclopentadiene- Senafylene adduct, 1,4-methano-1,4,4a, 9a-tetrahydrofluorene derivative, 1,4-methano-1,4,4a, 5,10,10a-hexahydroanthracene derivative, C3-20 And the like. Especially, as a cyclic olefin, tetracyclo [4.4.0. ^{12, 5} . 1 ^7,10 ] -3-dodecene derivative, hexacyclo [6.6.1.1 ^3,6 . 1 ^10,13 . 0 ^2,7 . ^09,14 ] -4-heptadecene derivative, and tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene is more preferred. The ethylene / cyclic olefin copolymer may be a copolymer of ethylene and two or more kinds of cyclic olefins.

  The water vapor permeability of the ethylene polymer can be adjusted, for example, by adjusting the density of the ethylene polymer. Generally, when the density of the ethylene polymer is lowered, the water vapor transmission rate tends to increase. In order to reduce the density of the ethylene polymer, for example, (i) an ethylene polymer is prepared using a copolymer component (comonomer) having a bulky branched chain, and (ii) a polymerization reaction is performed under high pressure conditions. To increase the number of branches.

  The ethylene-based polymer may be a copolymer of ethylene, a monomer copolymerizable with ethylene, and an adhesion auxiliary component. The adhesion auxiliary component is a radically polymerizable unsaturated compound having a polar group such as a hydrogen bonding functional group. Such a copolymer can be obtained by copolymerizing ethylene, an α-olefin or a cyclic olefin, and an adhesion auxiliary component by a method such as graft copolymerization. The ethylene-based polymer obtained by copolymerizing such an adhesive strength auxiliary component can improve the adhesive strength to the surfaces to be joined.

  Examples of adhesive strength auxiliary components include hydroxyl group-containing ethylenically unsaturated compounds, amino group-containing ethylenically unsaturated compounds, epoxy group ethylenically unsaturated compounds, aromatic vinyl compounds, unsaturated carboxylic acids or their derivatives, vinyl ester compounds , Vinyl chloride, carbodiimide compounds and the like. Of these, unsaturated carboxylic acids or derivatives thereof are preferred.

  Specific examples of the adhesive strength auxiliary component include acrylic acid, methacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, Nadic acid (trademark) (endocis-bicyclo [2. 2.1] unsaturated carboxylic acids such as hept-5-ene-2,3-dicarboxylic acid).

  The adhesion assisting component may be a derivative of the aforementioned unsaturated carboxylic acid. Examples of unsaturated carboxylic acid derivatives include acid halides, amides, imides, anhydrides, and esters. Specific examples of unsaturated carboxylic acid derivatives include maleenyl chloride, maleimide, maleic anhydride, citraconic anhydride, 2-methylmaleic anhydride, 2-chloromaleic anhydride, and 2,3-dimethylmaleic anhydride. 4-methyl-4-cyclohexene-1,2-dicarboxylic anhydride monomethyl maleate, dimethyl maleate, glycidyl malate, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, methacryl Examples include butyl acid.

  An adhesive force auxiliary | assistant component can be used individually by 1 type or in combination of 2 or more types. As the adhesion auxiliary component, unsaturated dicarboxylic acid or anhydride thereof is suitable, and maleic acid, nadic acid, or acid anhydrides thereof are particularly suitable.

  The amount of the structural unit derived from the adhesive force auxiliary component contained in the ethylene polymer is usually 0.1 to 5 parts by weight, preferably 100 parts by weight of the structural unit other than the structural unit derived from the adhesive force auxiliary component. Is 0.1 to 4 parts by weight. If the content of the structural unit derived from the adhesive strength auxiliary component is within the above numerical range, the adhesive strength of the solar cell sealing film is sufficiently improved, and the transparency and flexibility are not adversely affected. preferable.

  The ethylene polymer is also preferably a silane-modified product modified with a polymerizable silane compound. Such a silane modified body can be obtained by graft copolymerizing ethylene, a monomer copolymerizable with ethylene, and a polymerizable silane compound using, for example, an organic peroxide.

  By graft copolymerizing the polymerizable silane compound, the functional group (silyloxy group or the like) of the polymerizable silane compound can be used as a side chain of the copolymer. Since the functional group of the polymerizable silane compound improves the adhesive strength of the copolymer, if the degree of freedom of the functional group of the polymerizable silane compound is increased, the adhesive strength is further improved.

  As the polymerizable silane compound for silane modification, a conventionally known compound can be used without any particular limitation. Of these, ethylenically unsaturated silane compounds are preferred. Specific examples of the ethylenically unsaturated silane compound include vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxy-ethoxysilane), γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane and the like are included.

  The amount of the structural unit derived from the polymerizable silane compound contained in the modified silane is usually 0.1 to 5 parts by weight, preferably 100 parts by weight of the structural unit other than the structural unit derived from the polymerizable silane compound. 0.1 to 4 parts by weight. When the content of the structural unit derived from the polymerizable silane compound is within the above numerical range, the adhesiveness of the solar cell sealing film is sufficiently improved and the transparency and flexibility are not adversely affected. Is preferable.

  The ethylene polymer can be produced by a known polymerization method. The method for producing the ethylene polymer is not particularly limited. The ethylene-based polymer is preferably produced by, for example, a gas phase polymerization method or a slurry polymerization method that requires a small amount of polymerization catalyst. If a large amount of a polymerization catalyst containing a metal element remains in an ethylene polymer, it cannot be generally said, but the insulating property of a solar cell sealing film containing the ethylene polymer as a main material tends to be lowered. For this reason, when a solar cell module is produced using such a sealing film for solar cells, it may cause ion migration or power generation efficiency may be lowered depending on the cell structure.

(Light stabilizer)
The light stabilizer contained in the solar cell sealing film of the present invention has a structure represented by the following general formula (1).

  In the general formula (1), X represents an alkyl group, alkenyl group, alkyloxy group, alkenyloxy group, alkyloxycarbonyl group, alkenyloxycarbonyl group, aryloxycarbonyl group, acyl group, acyloxy group, alkyloxycarbonyloxy group. Alkenyloxycarbonyloxy group, aryloxycarbonyloxy group, alkylsulfonyl group, alkenylsulfonyl group, arylsulfonyl group, alkylsulfinyl group, alkenylsulfinyl group, arylsulfinyl group, sulfamoyl group, or carbamoyl group.

  Examples of the alkyl group include a methyl group and an ethyl group. Examples of the alkenyl group include an allyl group. Examples of the alkyloxy group include a methoxy group, an octyloxy group, and a cyclohexyloxy group. Examples of the alkenyloxy group include an allyloxy group. Examples of the alkyloxycarbonyl group include a methoxycarbonyl group and a hexadecyloxycarbonyl group. Examples of the alkenyloxycarbonyl group include an allyloxycarbonyl group. Examples of the aryloxycarbonyl group include a phenoxycarbonyl group and a p-chlorophenoxycarbonyl group. Examples of the acyl group include an acetyl group, a pivaloyl group, and a methacryloyl group. Examples of the acyloxy group include an acetoxy group and a benzoyloxy group. Examples of the alkyloxycarbonyloxy group include a methoxycarbonyloxy group and an octyloxycarbonyloxy group. Examples of the alkenyloxycarbonyloxy group include an allyloxycarbonyloxy group. Examples of the aryloxycarbonyloxy group include a phenoxycarbonyloxy group.

  Examples of the alkylsulfonyl group include a methanesulfonyl group and a butanesulfonyl group. Examples of the alkenylsulfonyl group include an allylsulfonyl group. Examples of the arylsulfonyl group include a benzenesulfonyl group and a p-toluenesulfonyl group. Examples of the alkylsulfinyl group include a methanesulfinyl group and an octanesulfinyl group. Examples of the alkenylsulfinyl group include an allylsulfinyl group. Examples of the arylsulfinyl group include a benzenesulfinyl group and a p-toluenesulfinyl group. Examples of the sulfamoyl group include a dimethylsulfamoyl group. Examples of the carbamoyl group include a dimethylcarbamoyl group and a diethylcarbamoyl group. X in the general formula (1) is preferably an alkyl group or an alkyloxy group.

  In the general formula (1), R represents a monovalent substituent. Specific examples of the “monovalent substituent” include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom; alkyl groups such as methyl group and ethyl group; aryl groups such as phenyl group and naphthyl group; A carboxyl group; an alkoxycarbonyl group such as a methoxycarbonyl group; an aryloxycarbonyl group such as a phenoxycarbonyl group; a substituted or unsubstituted carbamoyl group such as a carbamoyl group, an N-phenylcarbamoyl group, an N, N-dimethylcarbamoyl group; Alkylcarbonyl groups such as acetyl groups; arylcarbonyl groups such as benzoyl groups; nitro groups; substituted or unsubstituted amino groups such as amino groups, dimethylamino groups and anilino groups; acylamino groups such as acetamide groups and ethoxycarbonylamino groups; Sulfonamide groups such as methanesulfonamide groups; Imide groups such as imide groups and phthalimide groups; imino groups such as benzylideneamino groups; hydroxy groups; alkoxy groups such as methoxy groups; aryloxy groups such as phenoxy groups; acyloxy groups such as acetoxy groups; alkyls such as methanesulfonyloxy groups Sulfonyloxy group; arylsulfonyloxy group such as benzenesulfonyloxy group; sulfo group; substituted or unsubstituted sulfamoyl group such as sulfamoyl group and N-phenylsulfamoyl group; alkylthio group such as methylthio group; arylthio such as phenylthio group Groups; alkylsulfonyl groups such as methanesulfonyl group; arylsulfonyl groups such as benzenesulfonyl group; heterocyclic groups such as pyridyl group and morpholino group. These monovalent substituents may be further substituted. Moreover, when there are a plurality of substituents, they may be the same or different. Furthermore, it may combine with substituents and may form the ring.

  Specific examples of the light stabilizer represented by the general formula (1) include compounds represented by the following formulas (1-1) to (1-3). In addition, the compound etc. which are represented with the said General formula (1) can be mentioned.

  The amount of the light stabilizer represented by the general formula (1) contained in the solar cell sealing film is preferably 0.05 to 1 part by weight with respect to 100 parts by weight of the ethylene polymer, Particularly preferred is 0.05 to 0.3 parts by weight. When the content of the light stabilizer is less than 0.05 parts by weight, the light stability of the solar cell sealing film tends to decrease. On the other hand, if the content of the light stabilizer is more than 1 part by weight, the volume specific resistance of the cured product of the solar cell sealing film may decrease.

(Seal film for solar cell)
The melt flow rate (MFR) of the sealing film for solar cell of the present invention is 0.1 to 100 g / 10 min, preferably 0.5 to 50 g / 10 min, more preferably 0.5 to 20 g / 10 min. is there. In addition, MFR of the sealing film for solar cells is measured by 190 degreeC and a 2.16kg load based on JISK-7210.

  When the MFR of the solar cell sealing film is less than 0.1 g / 10 min, the fluidity is lowered, and the productivity at the time of extrusion molding is lowered. On the other hand, when the MFR of the solar cell sealing film is more than 100 g / 10 min, the fluidity is too high and sheet molding becomes difficult, and mechanical properties such as tensile strength decrease.

The MFR of the solar cell sealing film depends on the molecular weight of the ethylene polymer contained as the main material. Specifically, the larger the molecular weight of the ethylene polymer, the smaller the MFR value of the solar cell sealing film. Further, the smaller the molecular weight of the ethylene polymer, the larger the MFR value of the solar cell sealing film. It is known that the molecular weight of an ethylene-based polymer depends on the composition ratio of hydrogen and ethylene (hydrogen (H ₂ ) / ethylene) in the polymerization system (for example, Kazuo Soga, KODASHA, “CATALYTIC OLEFIN POLYMERISATION”). 376 (1990)). For this reason, an ethylene polymer having a desired molecular weight can be produced by appropriately increasing or decreasing the value of the ratio of “hydrogen (H ₂ ) / ethylene” in the polymerization system.

  The metal residue in the solar cell sealing film of the present invention is preferably 0.1 to 50 ppm by weight, more preferably 0.1 to 45 ppm by weight, and 0.1 to 40 ppm by weight. It is particularly preferred. If the metal residue is less than 0.1 ppm by weight, it may be necessary to deash the polymerization catalyst used during the synthesis of the ethylene polymer. For this reason, plant fixed cost, utility cost, etc. become high, and it exists in the tendency for product cost to become high. Furthermore, since the amount of acid or alkali used for the decalcification treatment increases, the possibility that the acid or alkali remains in the ethylene polymer increases. For this reason, an electrode etc. may corrode by the influence of the remaining acid and alkali. On the other hand, if the metal residue is more than 50 ppm by weight, it cannot be generally said, but the volume resistivity and dielectric breakdown resistance of the cured product may be reduced due to the influence of the metal residue.

  The metal residue in the solar cell sealing film depends on the polymerization activity of the polymerization catalyst (for example, metallocene compound) used during the synthesis of the ethylene polymer contained as the main material. When a polymerization catalyst having a high polymerization activity is used, the amount of the polymerization catalyst relative to the monomer can be reduced, so that metal residues in the resulting ethylene polymer can be reduced. For this reason, it can be said that using a polymerization catalyst having a high polymerization activity is one of suitable methods for obtaining an ethylene polymer and a solar cell sealing film with little metal residue. In addition, by polymerizing at the optimum polymerization temperature of the polymerization catalyst, increasing the polymerization pressure as much as possible, or increasing the monomer concentration per polymerization catalyst, etc., increase the polymerization activity of the polymerization catalyst and obtain an ethylene polymer This is a suitable technique for reducing metal residues in the sealing film for solar cells and solar cells.

  Moreover, when using as a polymerization catalyst the compound which reacts with an organoaluminum oxy compound, a metallocene compound, or forms an ion pair, or an organoaluminum compound, it is also possible to reduce the addition amount of these polymerization catalysts as much as possible. This is a suitable technique for reducing metal residues in the ethylene-based polymer and the solar cell sealing film. In addition, improving the polymerization activity using various techniques can also be a suitable technique for reducing metal residues. In addition, there is also a technique for reducing metal residues by decalcifying using a chelating agent such as acid, alkali, or methyl acetoacetate. However, when an acid, an alkali, or a chelating agent remains in the ethylene polymer, corrosion of the thin film electrode may be accelerated. For this reason, it cannot be said that the method of reducing a metal residue by such a decalcification process is suitable.

  The solar cell sealing film of the present invention has a high gel fraction while containing an additive such as a light stabilizer. That is, it is considered that a cured product having high volume resistance can be obtained because the HALS is entangled and the crosslinking proceeds rapidly, resulting in difficulty in polarization.

(Additive)
The solar cell sealing film of the present invention contains components (additives) other than the above-described ethylene-based polymers and light stabilizers as necessary, as long as the effects of the present invention are not impaired. Also good. Specific examples of the additive include a cross-linking agent, an adhesion auxiliary agent, a cross-linking auxiliary agent and the like.

  The crosslinking agent is a component that can cause the polymer component contained in the solar cell sealing film to undergo a cross-linking reaction and improve the heat resistance and weather resistance of the solar cell sealing film. In general, the crosslinking agent is preferably an organic peroxide that generates radicals at 100 ° C. or higher. In particular, in consideration of the stability at the time of blending, an organic peroxide having a decomposition temperature of 70 hours or higher with a half-life of 10 hours is further increased. preferable.

  Examples of organic peroxides include 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 3-di-t-butyl peroxide, t-dicumyl peroxide, 2,5- Dimethyl-2,5-di (t-butylperoxy) hexyne, dicumyl peroxide, α, α'-bis (t-butylperoxyisopropyl) benzene, n-butyl-4,4-bis (t-butyl Peroxy) butane, 2,2-bis (t-butylperoxy) butane, 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) 3, 3,5 -Trimethylcyclohexane, t-butylperoxybenzoate, benzoyl peroxide and the like.

  The amount of the crosslinking agent contained in the solar cell sealing film is preferably 0.1 to 3.0 parts by weight with respect to 100 parts by weight of the polymer component including the ethylene polymer, and 0.2 to More preferably, it is 2.0 parts by weight.

  The adhesive force auxiliary agent is a component added to improve the adhesive force of the solar cell sealing film. As the adhesion auxiliary agent, a silane compound is preferable, and a silane coupling agent is more preferable. Specific examples of the silane coupling agent include γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris- (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-ethoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and N-β- ( Aminoethyl) -γ-aminopropyltrimethoxysilane and the like. The silane compound used as an adhesion aid may be a silane-modified resin.

  From the viewpoint of the stability of the adhesion aid, alkoxysilanes are preferably used among the silane compounds. This is because alkoxysilanes exist relatively stably in a neutral pH range at room temperature. However, since alkoxysilanes have high stability, the adhesive force of the solar cell sealing film may be difficult to develop when a solar cell module is manufactured.

  The amount of the adhesion aid contained in the solar cell sealing film is preferably 0.1 to 3.0 parts by weight with respect to 100 parts by weight of the polymer component including the ethylene polymer. More preferably, it is 2 to 1.5 parts by weight.

  It is preferable that the silane compound used as an adhesion aid and the above-described polymerizable silane compound have a reactive group (such as an alkoxy group or a halogen group) bonded to a silicon (Si) atom. The reactive group bonded to the silicon atom reacts with a member that is in contact with the solar cell sealing film in the solar cell module (that is, a solar cell formed of silicon or the like, or a surface protection member formed of an inorganic substance such as glass). This is because a physical bond such as a chemical bond or a hydrogen bond can be formed. Such physical bonding is considered to greatly improve the adhesion between the solar cell sealing film and the protective member.

  The higher the activity and the greater the number of reactive groups of the reactive group bonded to the silicon atom, the higher the adhesion of the solar cell sealing film. On the other hand, if the activity of the reactive group is too high, the adhesive force auxiliary agent tends to react when the solar cell sealing film is stored, and it may be difficult to impart adhesiveness when manufacturing the solar cell module.

  The crosslinking aid can increase the crosslinking reactivity of the polymer component contained in the solar cell sealing film and improve the durability of the solar cell sealing film. Examples of the crosslinking aid include polyfunctional polymerizable compounds. More specifically, the crosslinking aid includes trifunctional crosslinking aids such as triallyl isocyanurate, triallyl isocyanate, trimethylolpropane triacrylate, N, N′-m-phenylenebismaleimide, ethylene glycol diester. A methacrylate etc. can be mentioned.

  The amount of the crosslinking aid contained in the solar cell sealing film is preferably 0 to 1 part by weight, and 0 to 0.5 part by weight with respect to 100 parts by weight of the polymer component including the ethylene polymer. More preferably. By setting the content of the crosslinking aid within the above numerical range, it is possible to suppress a decrease and fluctuation in the output of the solar cell module due to a temperature change during power generation.

(Other additives)
The sealing film for solar cells of the present invention may contain “other additives” other than the above additives as long as the effects of the present invention are not impaired. Examples of “other additives” include colorants, ultraviolet absorbers, anti-aging agents, anti-discoloring agents, heat stabilizers, antioxidants, and the like.

  Examples of the colorant include inorganic pigments such as metal oxides and metal powders; and organic pigments such as azo-based, phthalocyanine-based, azo-based, acidic or basic dye-based lakes.

  Examples of UV absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 4- Benzophenone series such as dodecyloxy-2-hydroxybenzophenone; 2- (2′-hydroxy-5-methylphenyl) benzotriazole, 2- (3-tert-butyl-2-hydroxy-5-methylphenyl) -5-chlorobenzo Benzotriazole type such as triazole; Salicylate type such as phenyl salicylate, pt-butylphenyl salicylate; 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- Triazines such as [2- (2-ethylhexanoyloxy) ethoxy] phenol It is included.

(Method for producing sealing film for solar cell)
The solar cell sealing film of the present invention is obtained by, for example, melting and kneading a resin composition containing the above-described components (at least an ethylene polymer and a light stabilizer) using a T-die extrusion molding machine. After being extruded as a sheet, it can be produced by cooling and solidifying. The thickness of the solar cell sealing film is, for example, about 100 to 2000 μm. The sealing film for solar cells may be embossed on the surface in terms of improving cushioning properties and deaeration properties in the heat curing step.

2. Solar cell module The solar cell module of the present invention includes a front surface side transparent protective member, a back surface side protective member, a plurality of solar cells, and a sealing member. The plurality of solar cells are sandwiched between the front surface side transparent protective member and the back surface side protective member. Moreover, the sealing member has sealed the several photovoltaic cell between the surface side transparent protection member and the back surface side protection member. The sealing member is comprised by the hardened | cured material of the above-mentioned sealing film for solar cells. Moreover, a sealing member can be formed by arrange | positioning the above-mentioned sealing film for solar cells to the surface side and back surface side of a photovoltaic cell, and pressure-bonding sealing. Therefore, the basic structure of the solar cell module of the present invention is the front surface side transparent protective member / sealing member / solar cell / sealing member / back surface side protective member.

(Front side transparent protective member)
There is no restriction | limiting in particular in the kind of surface side transparent protection member, The surface side protection member generally used in the conventional solar cell module can be used. Since the surface-side transparent protective member is located on the outermost layer of the solar cell module, it ensures long-term reliability in outdoor exposure of the solar cell module, including weather resistance, water repellency, contamination resistance, and mechanical strength. It is preferable to have the following performance. Moreover, in order to utilize sunlight effectively, it is preferable that it is a highly transparent sheet | seat with a small optical loss.

  Examples of the material constituting the surface side transparent protective member include polyester resin, fluorine resin, acrylic resin, resin film made of ethylene / vinyl acetate copolymer, cyclic olefin (co) polymer, glass, etc. included.

  A resin film suitable as the surface-side transparent protective member is a fluorine-based resin film that is excellent in terms of weather resistance and the like. Specifically, tetrafluoroethylene / ethylene / copolymer (ETFE), polyvinyl fluoride resin (PVF), polyvinylidene fluoride resin (PVDF), polytetrafluoroethylene / resin (TFE), tetrafluoroethylene -Preferred are hexafluoropropylene copolymer (FEP), poly (trifluoroethylene fluoride) resin (CTFE), and the like. From the viewpoint of weather resistance, polyvinylidene fluoride resin is excellent. On the other hand, from the viewpoint of achieving both weather resistance and mechanical strength, ethylene tetrafluoride / ethylene / copolymer is excellent.

  Glass suitable as the surface-side transparent protective member is a glass substrate having a total light transmittance of 80% or more, preferably 90% or more, of light having a wavelength of 350 to 1400 nm. Among them, white plate glass with little absorption in the infrared region is preferable.

  Moreover, although the glass used as a surface side transparent protection member may be the tempered glass heat-processed in order to raise mechanical strength, the float plate glass which is not heat-processed may be sufficient. Moreover, since it is necessary to endure wind pressure, the glass used as a surface side transparent protection member is the thickness of about 3 mm. The glass is preferably reinforced with an aluminum frame.

  In order to improve the adhesion between the surface-side transparent protective member and other members such as a sealing member, the surface-side transparent protective member is preferably subjected to corona treatment or plasma treatment. Further, the light-receiving surface side of the front surface side transparent protective member is usually subjected to antireflection coating or embossing in order to suppress light reflection.

(Back side protection member)
There is no restriction | limiting in particular in the kind of back surface side protection member, The back surface side protection member generally used in the conventional solar cell module can be used. In addition, you may comprise a back surface side protection member with the material similar to the above-mentioned surface side transparent protection member.

  The back surface side protection member needs to have a function of preventing moisture from entering the solar cell module. Since the sealing member may have water absorption and moisture permeability, the function of preventing the moisture intrusion of the back surface side protection member is important. However, since the sealing member constituting the solar cell module of the present invention is a cured product of the above-described sealing film for solar cells, it absorbs water and transmits water more than the cured product of the conventional sealing film for solar cells. Low wetness.

  It is desirable that the back surface side protection member has light resistance against reflected light from the ground or the like and heat resistance that can withstand a temperature of 60 to 100 ° C. On the other hand, since the back surface side protection member does not assume the passage of sunlight, the transparency required for the front surface side protection member is not necessarily required.

  Specific examples of the back surface side protective member include (i) a white or black flame retardant PET film bonded to a PET film on which a moisture-proof film made of silicon oxide or aluminum oxide is deposited, (ii) one side or The thing which bonded the fluorine fluoride resin film on both surfaces further, etc. can be mentioned.

  You may provide the back surface side protection member with the reflection function or scattering function of light. By providing the back surface side protection member with a light reflection function or a light scattering function, the light use efficiency can be improved. There is no particular limitation on the method for imparting the light reflecting function or the scattering function to the back surface side protective member. For example, a metal layer may be provided in order to provide a reflection function. Further, in order to impart a scattering function, light scattering fine particles may be added.

(Solar cell)
The solar battery cell is not particularly limited as long as it can generate power using the photovoltaic effect of the semiconductor. Examples of solar cells include silicon (single crystal, polycrystalline, amorphous) solar cells, compound semiconductors (Groups 3-5, 2-6, etc.) solar cells, wet solar cells, Organic semiconductor solar cells and the like are included. Among these, a polycrystalline silicon solar cell is preferable from the viewpoint of balance between power generation performance and cost.

  Both silicon solar cells and compound semiconductor solar cells have excellent characteristics as solar cells, but are easily damaged by external stress or impact. However, the sealing member which is the cured product of the solar cell sealing film of the present invention is excellent in flexibility and can absorb stress and impact on the solar battery cell. For this reason, if the sealing film for solar cells of this invention is used, the damage of a photovoltaic cell can be suppressed effectively. Therefore, in the suitable aspect of a solar cell module, the sealing member which is the hardened | cured material of the sealing film for solar cells has joined directly to the photovoltaic cell.

  The solar cell is usually provided with a collecting electrode for taking out the generated electricity. Examples of current collecting electrodes include bus bar electrodes, finger electrodes, and the like. You may arrange | position a collector electrode on both surfaces of the surface of a photovoltaic cell, and a back surface. However, if the collecting electrode is disposed on the light receiving surface, the collecting electrode may block light, which may cause a problem that power generation efficiency decreases.

  In order to improve the power generation efficiency, it is conceivable to use a back-contact solar cell that does not require a collecting electrode on the light receiving surface. In one aspect of the back contact solar cell, p-doped regions and n-doped regions are alternately provided on the back surface side provided on the opposite side of the light receiving surface of the solar cell. In another aspect of the back contact type solar cell, a p / n junction is formed on a substrate provided with a through hole (through hole), and the surface (light receiving surface) side of the through hole inner wall and the through hole peripheral portion on the back surface side is formed. A doped layer is formed, and the current on the light receiving surface is taken out on the back side.

  In a back contact solar cell (particularly, a solar cell that extracts charges only on the back surface of the light receiving surface), the charge extraction site is biased toward and close to the back surface. Therefore, compared to a solar cell in which a collecting electrode is also arranged on the light receiving surface, the generated charge is less likely to flow in the back contact type solar cell, and moreover, a bias of charge is likely to occur in the sealing film on the light receiving surface side. it is conceivable that. Therefore, it is considered that the back contact solar cell is easily affected by the surrounding environment, for example, the electrical properties of the sealing member that seals the solar cell.

  Therefore, the solar cell sealing film of the back contact solar cell is more required to have less influence on the extraction of the generated charge of the solar cell. In order to make it difficult to influence the extraction of the generated charge, it is preferable that the volume specific resistance of the cured product of the solar cell sealing film is high. As described above, since the volume resistivity of the cured product of the solar cell sealing film of the present invention is high, it is suitably used as a material for constituting a back contact solar cell.

  Arbitrary members may be appropriately disposed in the solar cell module of the present invention as long as the object of the present invention is not impaired. Examples of the optional member include, but are not limited to, an adhesive layer, a shock absorbing layer, a coating layer, an antireflection layer, a back surface rereflection layer, a light diffusion layer, and the like. There are no particular limitations on the positions at which these layers are disposed, and it is preferable to dispose them at appropriate positions in consideration of the purpose of providing these layers and the characteristics of these layers.

3. Manufacturing method of solar cell module The manufacturing method of the solar cell module of this invention is a surface side transparent protective member, the 1st sealing film for solar cells, a photovoltaic cell, and the 2nd sealing film for solar cells, And a step (i) of forming a laminate by laminating the back surface side protective member in this order, and a step (ii) of integrating the obtained laminate by heating and pressing. The first sealing film for solar cell and the second sealing film for solar cell used in the step (i) are the above-described sealing film for solar cell of the present invention.

  When the uneven shape (embossed shape) is formed on the surface of the solar cell sealing film, in step (i), the surface on which the embossed shape is formed is arranged on the solar cell side. It is preferable to laminate | stack the sealing film for solar cells.

  In addition, in the manufacturing method of a solar cell module, it replaces with said process (i), the surface side transparent protection member, the sealing film for solar cells, and the back surface side protection member in which the photovoltaic cell was provided in the surface, In this order, the solar cell sealing film and the solar battery cell provided on the surface of the back surface side protective member may be laminated to form a laminate (i ′). Similarly, instead of the above step (i), a front surface side transparent protective member provided with solar cells on the surface, a solar cell sealing film, and a back surface side protective member are arranged in this order and the solar cell. It can also be set as the process (i '') which laminates | stacks so that the sealing film for solar cells and the photovoltaic cell provided in the surface of the surface side protection member may contact, and forms a laminated body. Thus, process (i) When the step (i ′) or the step (i ″) is employed instead, the method for producing a thin-film solar cell module is particularly suitable.

  In the step (ii), the laminate obtained in the step (i) may be integrated (sealed) by heating and pressurizing using a vacuum laminator according to a conventional method. Since the sealing film for solar cells of the present invention has high cushioning properties, cell damage due to pressurization during sealing can be prevented. Moreover, since the deaeration property is good, high-quality solar cell modules can be manufactured with high yield without involving air.

  At the time of manufacturing the solar cell module, a resin composition containing an ethylene polymer contained in the solar cell sealing film is crosslinked and cured. This crosslinking step may be performed simultaneously with step (ii) or after step (ii).

  When the crosslinking step is performed after step (ii), first, in step (ii), vacuum heating is performed for 3 to 6 minutes under the conditions of a temperature of 125 to 155 ° C. and a vacuum pressure of 10 Torr or less. Subsequently, pressurization by atmospheric pressure is performed for about 1 to 5 minutes to integrate the laminate. The crosslinking step performed after step (ii) can be performed by a general method. For example, a tunnel-type continuous crosslinking furnace may be used, or a shelf-type batch-type crosslinking furnace may be used. Moreover, crosslinking conditions are 140-155 degreeC normally for about 30-40 minutes.

  On the other hand, when the crosslinking step is performed simultaneously with the step (ii), the crosslinking step is performed except that the heating temperature in the step (ii) is 145 to 155 ° C. and the pressurizing time by atmospheric pressure is 6 to 15 minutes. It can be performed in the same manner as in the case after step (ii).

  In any case, in the method for producing a solar cell module of the present invention, the solar cells are solar-treated at a temperature at which the crosslinking agent is not substantially decomposed and the solar cell sealing film of the present invention melts. The battery sealing film may be temporarily bonded, and then the temperature may be raised to sufficiently bond and cross-link the solar battery sealing film. An additive formulation that satisfies various conditions may be selected. For example, it is preferable to appropriately select the type and content of a crosslinking agent, a crosslinking aid, and the like.

  EXAMPLES Next, although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples.

1. Measurement method of physical properties [water vapor permeability]
The water vapor transmission rate (%) of the polymer component at 23 ° C. and 90% RH was measured according to the “moisture permeable cup method” based on JIS K0208-1976.

[MFR]
Based on JIS K-7210, MFR (g / 10min) of the sealing film for solar cells was measured at 190 degreeC and the load of 2.16kg.

[Metal residue]
After the solar cell sealing film is wet-decomposed, the volume is adjusted with pure water, and using an ICP emission analyzer (trade name “ICPS-8100”, manufactured by Shimadzu Corporation), aluminum, zirconium, titanium, hafnium, And magnesium were quantified. The total amount of these metal elements was defined as “metal residue (weight ppm)”.

[Gel fraction]
The gel fraction (% by weight) of the solar cell sealing film was measured and calculated according to the method described in JP-A-2008-91772.

[Volume resistivity]
The solar cell sealing film was cut into a size of 10 cm × 10 cm × about 0.4 mm, and then laminated at 150 ° C., a vacuum of 3 minutes, and a pressure of 10 minutes to prepare a measurement sheet. The volume resistivity (Ω · cm) of the produced sheet was measured at an applied voltage of 500 V in accordance with ASTM-D257-93. The measurement environment was a temperature of 23 ± 2 ° C. and a humidity of 50 ± 5% RH. In addition, the trade name “R8340A” (manufactured by Advanced) was used as the measuring machine.

2. Components used <Ethylene polymer>
Ethylene / propylene / 5-ethylidene-2-norbornene copolymer (EPDM) (trade name “Mitsui EPT X-3012P”, manufactured by Mitsui Chemicals, ethylene content: 73 wt%, propylene content: 22.9 wt%, 5 -Ethylidene-2-norbornene (ENB) content: 4.1 wt%, water vapor transmission rate: 0.6 g · mm / (m ² · 24 h))

<Crosslinking agent>
2,5-Dimethyl-2,5-bis (t-butylperoxy) hexane

<Silane coupling agent>
γ-methacryloxypropyltrimethoxysilane

<Crosslinking aid>
Triallyl isocyanurate (TAIC)

<Light stabilizer>
Light stabilizer (1): Compound represented by the formula (1-1) Light stabilizer (2): Compound represented by the formula (1-2) Light stabilizer (3): The formula Compound represented by (1-3) Light stabilizer (4): Compound represented by the following formula (2)

3. Production of solar cell sealing film (Example 1)
100 parts by weight of an ethylene polymer, 0.1 part by weight of a light stabilizer (1), 0.1 part by weight of a light stabilizer (2), 1 part by weight of a crosslinking agent, 1.2 parts by weight of a crosslinking aid, and A resin composition containing 0.1 part by weight of a silane coupling agent was prepared. The sheet-shaped molten web of the prepared resin composition was extruded to obtain a solar cell sealing film having a thickness of 0.45 mm. The obtained solar cell sealing film (resin composition) had an MFR of 4 g / 10 min, a metal residue of 5 ppm by weight or less, and a gel fraction of 64.9% by weight. In addition, the volume resistivity of the cured product of the solar cell sealing film was 6.61 × 10 ¹⁷ Ω · cm.

(Example 2, Comparative Examples 1 and 2)
A solar cell sealing film was obtained in the same manner as in Example 1 except that the formulation shown in Table 1 was used (for Comparative Example 1, various additives were added to the polymer component (resin). A solar cell sealing film was used as it was without blending). Table 1 shows the measurement results of various physical property values of the obtained solar cell sealing film (resin composition) and its cured product.

4). Evaluation From the results shown in Table 1, the cured product of the solar cell sealing film of Examples 1 and 2 has a higher volume resistivity than the cured product of the solar cell sealing film of Comparative Examples 1 and 2. Is clear. For this reason, if the sealing film for solar cells of Example 1 and 2 is used, it is suggested that it is excellent in light stability and can provide a solar cell module with high electric power generation efficiency.

  Further, when Comparative Example 2 is compared with Examples 1 and 2, when HALS represented by a specific structural formula is added to an ethylene polymer having a water vapor transmission rate within a predetermined numerical range, it is obtained. It can be seen that the volume resistivity of the cured product of the solar cell sealing film is significantly increased.

  The sealing film for solar cells of the present invention has a property that the cured product has a high volume resistivity and is difficult to be charged. For this reason, when the sealing film for solar cells of the present invention is used as a material for the sealing member, it is possible to manufacture a solar cell module that hardly causes ion migration and has high power generation efficiency.

Claims (5)

An ethylene polymer having a water vapor permeability of 0.1 to 1 g · mm / (m ² · 24 h) at 23 ° C. and 90% RH;
And 0.05 to 1 part by weight of the light stabilizer represented by any one of the following general formulas (1-1) to (1-3) with respect to 100 parts by weight of the ethylene polymer ,
The sealing film for solar cells whose melt flow rate (MFR) measured by 190 degreeC and a 2.16kg load is 0.1-100 g / 10min based on JISK-7210.

  The solar cell sealing film according to claim 1, wherein the ethylene polymer is at least one of an ethylene / α-olefin / diene copolymer and an ethylene / α-olefin copolymer.   The solar cell sealing film according to claim 1, further comprising at least one of a crosslinking agent and an adhesion auxiliary agent. A surface-side transparent protective member, a back-side protective member, a plurality of solar cells sandwiched between the surface-side transparent protective member and the back-side protective member, the surface-side transparent protective member, and the back-side protective member; A sealing member for sealing the solar battery cell between,
The solar cell module whose said sealing member is the hardened | cured material of the sealing film for solar cells as described in any one of Claims 1-3 . And the surface-side transparent protective member, and the claims 1-3 for any one in the first solar cell sealing film according, the solar cell according to any one of claims 1 to 3 CHAPTER A step (i) of forming a laminate by laminating the second solar cell sealing film and the back surface side protective member in this order;
A step (ii) of heating and pressurizing and integrating the laminate obtained in the step (i);
A method for manufacturing a solar cell module, comprising: