JP2012041466A - Resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition suitable as a sealing material for solar cells excellent in transparency, heat resistance, adhesion, flexibility, moldability, durability and insulating properties.SOLUTION: The resin composition contains an ethylene-based copolymer, a crosslinking agent, and monomethyl diallyl isocyanurate represented by chemical formula (I) as a crosslinking aid.

Description

  The present invention relates to a resin composition suitably used as a sealing material for solar cells.

  A power generation element (hereinafter simply referred to as a power generation element) used in a solar cell is protected from intrusion of foreign matter, moisture, and the like by being sandwiched between sealing materials in order to avoid contact with outside air. This encapsulant has high transparency and excellent light transmission, excellent heat resistance, good adhesion to glass and backsheets that are protective materials, and sunlight. Functions such as not causing significant deterioration and yellowing are required, and various formulations of resin compositions suitable for such requirements have been studied (for example, Patent Document 1).

JP 2007-281135 A

  An object of the present invention is to provide a resin composition suitably used as a sealing material for solar cells, which is excellent in transparency, heat resistance, adhesiveness, flexibility, moldability, durability, and insulating properties. .

  As a result of intensive studies in order to solve the above problems, the present inventors have found that an ethylene copolymer and a crosslinking agent, and a resin containing monomethyldiallyl isocyanurate represented by the chemical formula (I) as a crosslinking aid. By making the composition, it was found that the intended purpose was achieved, and the present invention was completed.

  ADVANTAGE OF THE INVENTION According to this invention, the sealing material for solar cells excellent in transparency, heat resistance, adhesiveness, a softness | flexibility, a moldability, durability, and an insulation characteristic can be obtained.

Hereinafter, the present invention will be described in detail.
The ethylene copolymer used in the practice of the present invention is a copolymer of ethylene and a polar monomer (hereinafter referred to as ethylene / polar monomer copolymer) and an α-olefin copolymer.

Examples of the polar monomer include α, such as acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, itaconic acid, itaconic anhydride, and bicyclo [2.2.1] -5-heptene-2,3-dicarboxylic acid. β-unsaturated carboxylic acids and metal salts thereof such as sodium, potassium, lithium, zinc, magnesium, calcium;
Methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid α, β-unsaturated carboxylic acid esters such as n-propyl, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate;
Unsaturated dicarboxylic acids such as maleic acid and itaconic acid;
Vinyl esters such as vinyl acetate, vinyl propionate, vinyl caproate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl trifluoroacetate;
Unsaturated glycidyl group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, monoglycidyl itaconate, and the like, and units introduced from these polar monomers are used in the ethylene / polar monomer copolymer as one type or You may contain 2 or more types.

  The ethylene / polar monomer copolymer may contain units derived from ethylene in a proportion of 99.5 to 0.5 mol%, preferably 99 to 1 mol%. It may be contained at a ratio of 0.5 to 99.5 mol%, preferably 1 to 99 mol%.

The ethylene / polar monomer copolymer includes, for example, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, in addition to ethylene and the above-mentioned polar monomer. 3-ethyl-1-pentene, 4-methyl-1-pentene, 4,4-dimethyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4-ethyl-1 Α-olefins having 3 to 20 carbon atoms such as -hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene ;
Cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, tetracyclododecene, 2-methyl-1,4,5,8-dimethano-1,2,3,4,4a, 5,8,8a-octa C3-C20 cyclic olefins such as hydronaphthalene;
Aromatic vinyl compounds such as styrene, substituted styrenes, allylbenzene, substituted allylbenzenes, vinylnaphthalenes, substituted vinylnaphthalenes, allylnaphthalenes, substituted allylnaphthalenes;
Alicyclic vinyl compounds such as vinylcyclopentane, substituted vinylcyclopentanes, vinylcyclohexane, substituted vinylcyclohexanes, vinylcycloheptane, substituted vinylcycloheptanes, allyl norbornane;
Silane unsaturated compounds such as allyltrimethylsilane, allyltriethylsilane, 4-trimethylsilyl-1-butene, 6-trimethylsilyl-1-hexene, 8-trimethylsilyl-1-octene, 10-trimethylsilyl-1-decene;
One selected from conjugated or non-conjugated dienes such as butadiene, 1,4-hexadiene, 7-methyl-1,6-octadiene, 1,8-nonadiene, 1,9-decadiene, norbornadiene, dicyclopentadiene, etc. Alternatively, two or more types of monomers may be copolymerized.

As a specific example of such an ethylene / polar monomer copolymer,
Ethylene / acrylic acid copolymer,
Ethylene / methyl acrylate copolymer,
Ethylene / ethyl acrylate copolymer,
Ethylene / isopropyl acrylate copolymer,
Ethylene / n-butyl acrylate copolymer,
Ethylene / isobutyl acrylate copolymer,
Ethylene / ethyl acrylate 2-ethylhexyl copolymer,
Ethylene / methacrylic acid copolymer,
Ethylene / methyl methacrylate copolymer,
Ethylene / ethyl methacrylate copolymer,
Ethylene / isopropyl methacrylate copolymer,
Ethylene / n-butyl methacrylate copolymer,
Ethylene methacrylate isobutyl copolymer,
Ethylene / methacrylic acid 2-ethylhexyl copolymer,
Ethylene / vinyl acetate copolymer,
Ethylene / vinyl propionate copolymer,
Ethylene / ethyl acrylate / maleic anhydride copolymer,
Ethylene / ethyl acrylate / glycidyl methacrylate copolymer,
Ethylene / vinyl acetate / glycidyl methacrylate copolymer,
Examples thereof include ethylene / glucidyl methacrylate copolymers, which can be preferably used.

  The α-olefin copolymer is composed mainly of ethylene or propylene, and one or more of α-olefins having 4 to 10 carbon atoms as subcomponents, and in combination with a diene monomer as necessary. Polymerized.

The copolymer containing ethylene as a main component has an ethylene polymer unit of 50 to 90 mol%, preferably 70 to 85 mol%, and an α-olefin polymer unit other than ethylene of 50 to 10 mol%, preferably 30 to 15 mol%. %, And if necessary, diene monomer polymerization units are contained in a proportion of 2 mol% or less, preferably 1 mol% or less.
As a specific example of such an ethylene copolymer,
Ethylene / propylene copolymer,
Ethylene / 1-butene copolymer,
Ethylene-4-methyl-1-pentene copolymer,
Ethylene / 1-hexene copolymer,
Ethylene / 1-octene copolymer,
Ethylene / propylene / dicyclopentadiene copolymer,
Ethylene / propylene / 5-ethylidene-2-norbornene copolymer,
Examples thereof include ethylene / propylene / 1,6-hexadiene copolymer, which can be preferably used.

The copolymer mainly composed of propylene has a propylene polymerization unit of 70 to 95 mol%, preferably 72 to 90 mol%, and an α-olefin polymerization unit other than propylene of 5 to 30 mol%, preferably 10 to 10 mol%. It is contained at a ratio of 28 mol%.
Specific examples of such a propylene-based copolymer include a propylene / ethylene copolymer and a propylene / 1-butene copolymer, and these can be preferably used.

  As the crosslinking agent used in the practice of the present invention, conventionally known organic peroxides or photopolymerization initiators (photosensitizers) can be used, and the amount is 0 with respect to 100 parts by weight of the ethylene copolymer. It is preferable to mix | blend in the ratio of 1-5 weight part. In addition, you may use it combining an organic peroxide and a photoinitiator.

  Examples of the organic peroxide include 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, , 5-dimethyl-2,5-bis (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-bis (tert-butylperoxy) -3-hexyne, dicumyl peroxide, tert-butyl Cumyl peroxide, α, α′-bis (2-tert-butylperoxyisopropyl) benzene, n-butyl-4,4-bis (tert-butylperoxy) valate, 2,2-bis (tert-butylperoxide) Oxy) butane, 1,1-bis (tert-butylperoxy) cyclohexane, 1,1-bis (tert-butylperoxy) 3, 3,5-trimethylcyclohexane, tert-butyl peroxybenzoate, benzoyl peroxide and the like may be mentioned, and these may be used in combination.

Examples of the photopolymerization initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- {4- (methylthio) phenyl}- Acetophenones such as 2-morpholinopropane-1;
Benzoins such as benzyldimethylketal;
Benzophenones such as benzophenone, 4-phenylbenzophenone, hydroxybenzophenone;
Thioxanthones such as isopropylthioxanthone and 2-4-diethylthioxanthone;
Other special examples include methylphenyl glyoxylate, and these may be used in combination.
These photopolymerization initiators can be used in combination with known photopolymerization accelerators such as benzoic acids such as 4-dimethylaminobenzoic acid and tertiary amines, if necessary.

The crosslinking aid used in the practice of the present invention is monomethyldiallyl isocyanurate, but is preferably blended at a ratio of 0.1 to 5 parts by weight with respect to 100 parts by weight of the ethylene copolymer.
In addition, as other crosslinking aid, an unsaturated compound having an allyl group or a (meth) acryloxy group can be used in combination as long as the effects of the present invention are not impaired.
Such unsaturated compounds include polyallyl compounds such as triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diallyl fumarate, diallyl maleate;
Poly (meth) acryloxy compounds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate;
Examples include divinylbenzene.

In the resin composition of the present invention, a silane coupling agent can be blended in order to increase the adhesive force between the power generation element and the sealing material.
Examples of such silane coupling agents include γ-chloropropylmethoxysilane, vinylethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, and γ-glycidoxypropyl. Trimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N Examples include -β- (aminoethyl) -γ-aminopropyltrimethoxysilane.
These silane coupling agents may be used alone or in combination of two or more, and are preferably blended at a ratio of 1 to 5 parts by weight with respect to 100 parts by weight of the ethylene copolymer.

  In the resin composition of the present invention, an antioxidant, a light stabilizer (ultraviolet absorber), and the like can be blended in order to prevent deterioration of the sealing material due to ultraviolet rays in sunlight.

Phenol-based antioxidants include 2,6-di-tert-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-tert-butyl-p-ethylphenol, stearyl-β- (3, Monophenols such as 5-di-t-butyl-4-hydroxyphenyl) propionate;
2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert) -Butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 3,9-bis [1,1-dimethyl-2- {β- (3-tert-butyl-4-hydroxy-) Bisphenols such as 5-methylphenyl) propionyloxy} ethyl] 2,4,8,10-tetraoxaspiro [5,5] undecane;
1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl -4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis- (4'-Hydroxy-3'-tert-butylphenyl) butyric acid] glycol ester, 1,3,5-tris (3 ', 5'-di-tert-butyl-4'-hydroxybenzyl) -S-triazine-2 Polymeric phenols such as 4,6- (1H, 3H, 5H) trione and tocophenol are exemplified.

Phosphorus antioxidants include triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonylphenyl) phosphite, diisodecylpentaerythritol phosphite, tris (2,4-di-tert-butyl) Phenyl) phosphite, cyclic neopentanetetraylbis (octadecyl) phosphite, cyclic neopentanetetraylbis (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis (2, Phosphors such as 4-di-tert-butyl-4-methylphenyl) phosphite, bis [2-tert-butyl-6-methyl-4- {2- (octadecyloxycarbonyl) ethyl} phenyl] hydrogen phosphite Door like;
9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10- (3,5-di-tert-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10 -Oxaphosphaphenanthrene oxides such as -phosphaphenanthrene-10-oxide, 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

Examples of the light stabilizer include salicylic acids such as phenyl salicylate, p-tert-butylphenyl salicylate, and p-octylphenyl salicylate;
2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2, Benzophenones such as 2′-dihydroxy-4,4′-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone;
2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′- Di-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5 '-Di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3', 5'-ditert-amylphenyl) benzotriazole, 2- {2'-hydroxy-3'- Benzotriazoles such as (3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl} benzotriazole;
Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (1,2,2,6,6) Hindered amines such as -pentamethyl-4-piperidyl) [{3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl} methyl] butyl malonate.

  These antioxidants and light stabilizers are preferably blended at a ratio of 0.1 to 3 parts by weight with respect to 100 parts by weight of the ethylene copolymer.

In addition to these, a fatty acid salt of a metal such as cadmium or barium can be added to the resin composition of the present invention, for example, as a discoloration preventing agent. In addition, since the sealing material used for the surface coating on the side opposite to the light receiving side of the solar cell does not require transparency, pigments, dyes, inorganic fillers, etc. are used for the purpose of coloring and improving power generation efficiency. Can be blended. Examples thereof include white pigments such as titanium oxide and calcium carbonate, blue pigments such as ultramarine, black pigments such as carbon black, glass beads, and light diffusing agents.
These additives are preferably blended in an amount of 0.5 to 50 parts by weight per 100 parts by weight of the ethylene copolymer.

  The resin composition of the present invention is usually heated and rolled into a sheet shape and used as a sealing material. Such a sheet can be formed using a T-die extruder, a calendar forming machine, an inflation forming machine or the like. For example, it can be manufactured by supplying a resin composition prepared beforehand by dry blending from a hopper of an extruder and extruding it into a sheet at a molding temperature of 50 to 90 ° C. The thickness of the sheet is not particularly defined, but is usually about 50 μm to 2 mm.

A solar cell module can be manufactured by using such a sheet for sealing material and fixing the power generation element with upper and lower protective materials. As such a solar cell module, for example, an upper transparent protective material / a sealing material sheet / a power generation element / a sealing material sheet / a lower protection material, which is sandwiched between the front and back surfaces of the power generation element with a sealing material Can be mentioned.
As another type of solar cell module, a structure in which a sealing material sheet and an upper transparent protective material are formed on a power generating element formed on the inner peripheral surface of the lower substrate protective material, the inner peripheral surface of the upper transparent protective material A structure in which a sealing material sheet and a lower protective material are formed on a power generation element formed above, for example, an amorphous power generation element formed on a fluororesin-based sheet by sputtering or the like can be exemplified.

  As power generation elements, various semiconductors of group 3-5 or group 2-6 elements such as silicon such as single crystal silicon, polycrystalline silicon, and amorphous silicon, and gallium-arsenic, copper-indium-selenium, cadmium-tellurium, etc. Can be mentioned.

  Examples of the upper protective material constituting the solar cell module include glass, acrylic resin, polycarbonate, polyester, and fluorine-containing resin. The lower protective material is a single or multi-layer sheet of metal or various thermoplastic resin films, for example, metals such as tin, aluminum, stainless steel, inorganic materials such as glass, polyester, inorganic vapor-deposited polyester, fluorine-containing A single-layer or multilayer sheet of resin, polyolefin, etc. can be mentioned.

The solar cell module is manufactured by using a sealing material for the power generating element and the protective material at a temperature at which the crosslinking agent is not substantially decomposed and the sheet-shaped sealing material molded from the resin composition of the present invention melts. Temporary bonding may be performed, and then the temperature may be further increased to sufficiently bond and crosslink.
The degree of crosslinking of the ethylene-based copolymer is preferably in the range of 70 to 98% in consideration of the insulating properties. The crosslinking reaction can be performed by heating the resin composition of the present invention to about 100 to 200 ° C.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these. In addition, the measuring method of a haze value and a total light transmittance is shown below.

[Measurement of haze value / total light transmittance]
A 0.5 mm thick sheet was sandwiched between two 3 mm thick blue glass sheets, which were laminated at 150 ° C. for 15 minutes with a vacuum laminator, and the haze value and total light transmittance were measured according to JIS K7105.

[Example 1]
100 parts by weight of ethylene / vinyl acetate copolymer (vinyl acetate content: 25%, melt index value: 4) as an ethylene copolymer, 1 part by weight of dicumyl peroxide as a crosslinking agent, and monomethyldiallyliso as a crosslinking aid A resin composition prepared by mixing 5 parts by weight of synurate and 0.3 parts by weight of γ-methacryloxypropyltrimethoxysilane as a silane coupling agent was thickened at a processing temperature of 100 ° C. using a profile extruder. A 0.5 mm sheet was prepared.
The haze value and total light transmittance of this sheet were measured and shown in Table 1.

[Examples 2 to 4, Comparative Examples 1 to 4]
A sheet having the composition shown in Table 1 was prepared in the same manner as in Example 1, and the haze value and total light transmittance were measured and shown in Table 1.

ADVANTAGE OF THE INVENTION According to this invention, the resin composition anticipated for the use as a sealing material for solar cells can be provided.

Claims (1)

A resin composition comprising an ethylene copolymer and a crosslinking agent, and monomethyldiallyl isocyanurate represented by the chemical formula (I) as a crosslinking aid.