JP5688323B2 - Adhesive resin composition for solar cell backsheet and solar cell backsheet using the same - Google Patents

Description

  The present invention relates to an adhesive composition used for laminating a base material of a back sheet of a solar cell made of a resin and polycarbodiimide, and a back sheet for a solar cell having an adhesive layer made of the adhesive.

  In recent years, conventional power generation methods such as thermal power generation have been regarded as problems such as depletion and soaring of fossil fuels such as oil and coal, and generation of greenhouse gases such as carbon dioxide. On the other hand, solar cells that directly convert solar energy into electric power have attracted attention, and demand is expanding.

  Until now, the durability of solar cells has been about 10 years, but in recent years, the demand has further increased, and the durability of about 20 to 30 years has been demanded.

  Generally, a solar cell is composed of a solar cell such as a silicon power generation element and a panel material on which the cell is mounted. This panel material is comprised from the surface side transparent protection member which consists of the surface side and back surface side sealing film which seals the cell for solar cells, a glass substrate, etc., a back surface side protection member (back sheet), etc.

  Materials used for back sheets in solar cells include base materials such as polyester films and fluorine resin films and urethane adhesives, amide adhesives, ester adhesives, acrylic adhesives, etc. Consists of adhesive.

  When solar cells are used outdoors for a long time in environments exposed to conditions such as high temperature and high humidity or wind and rain, the ester bond and the like contained in the adhesive component cause hydrolysis, resulting in a decrease in molecular weight and adhesion. It causes a drop in power. This leads to moisture intrusion into the solar cell, resulting in a decrease in the power generation characteristics and poor appearance of the solar cell, and consequently the durability of the solar cell.

  Therefore, in order to further improve the durability of solar cells and the like, it is necessary to suppress a decrease in adhesive force by suppressing hydrolysis of the adhesive component and a decrease in molecular weight due thereto.

  Therefore, for example, a back sheet for a solar cell has been proposed in which a monocarbodiimide compound is blended with a polyurethane-based adhesive to capture carboxylic acid generated when hydrolysis occurs and suppress hydrolysis of the adhesive component. .

  However, the monocarbodiimide compound is added for the purpose of capturing carboxylic acid generated by hydrolysis of the resin constituting the adhesive, and it is difficult to suppress a decrease in molecular weight. The decrease in molecular weight causes a decrease in adhesive strength, and has not yet sufficiently improved the durability of solar cells.

JP 2008-4691 A

  Therefore, in order to solve the above problems, the present invention captures carboxylic acid generated by hydrolysis of the resin constituting the adhesive and suppresses the decrease in molecular weight, thereby reducing the adhesive force even under high temperature and high humidity. An object of the present invention is to provide an adhesive for a solar battery backsheet with a low content and a solar battery backsheet using the same.

That is, the present invention
1. In the adhesive used to bond the substrates constituting the solar cell backsheet, the adhesive consists of a resin and a polycarbodiimide compound, an adhesive composition for solar cell backsheet,
2. 1. Adhesive composition for solar cell backsheet of 1, wherein the polycarbodiimide compound is a polycarbodiimide compound derived from an aliphatic diisocyanate and / or an alicyclic diisocyanate,
3. The adhesive composition for solar battery backsheet according to 2, wherein the aliphatic diisocyanate and the alicyclic diisocyanate are isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, tetramethylxylylene diisocyanate,
4). The adhesive composition for solar cell backsheet of 1-3 whose said resin is at least 1 sort (s) chosen from a polyester resin, a polyurethane resin, a polyamide resin, and an acrylic resin.
5. Provided is a solar battery backsheet using the adhesive for solar battery backsheets 1 to 4 as an adhesive layer.

  The adhesive composition for solar battery backsheet of this invention mix | blends a polycarbodiimide compound. The polycarbodiimide compound has a single molecular chain, and can capture a plurality of carboxylic acids generated by hydrolysis and connect molecules having a reduced molecular weight. Thereby, it is possible to provide an adhesive for a solar battery backsheet with little decrease in adhesive force by suppressing the reduction in molecular weight even under high temperature and high humidity.

  The polycarbodiimide compound can react with a carboxylic acid group, a hydroxyl group, and an amino group in the resin and acts as a crosslinking agent. Thereby, the intensity | strength of an adhesive agent increases and durability can be improved.

  Furthermore, since the solar cell backsheet having an adhesive layer made of this solar cell backsheet adhesive can suppress hydrolysis of the adhesive layer to which the base material is bonded, the solar cell has been used for a long period of time. Intrusion of moisture into the solar cell due to peeling of the adhesive layer at the time can be prevented, and as a result, the durability of the solar cell can be improved.

Hereinafter, the present invention will be described in more detail.
The adhesive composition for a solar battery backsheet of the present invention is a resin composition containing a resin and polycarbodiimide.

Examples of the resin constituting the adhesive composition used in the present invention include polyester resins, polyurethane resins, polyamide resins, acrylic resins, vinyl acetate resins, epoxy resins, polyethylene resins, polypropylene resins and the like, cyanoacrylate resins , Cellulose resins, polyether resins, polyimide resins, urea resins or melamine resins, amino resins, phenol resins, silicone resins, etc., but polyester resins and polyurethane resins for reasons such as adhesive strength, workability, and cost. Polyamide resins and acrylic resins are preferred.
These resins may be used alone or in combination.

The polyester resin can be usually obtained by condensation polymerization of a polyvalent carboxylic acid and a polyvalent hydroxy compound or ring-opening polymerization of a cyclic lactone compound.
Examples of the polyvalent carboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, phthalic acid, 4,4′-diphenyldicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, and 2,6-naphthalene. Dicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2-sodium sulfoterephthalic acid, 2-potassium sulfoterephthalic acid, 4-sodium sulfoisophthalic acid, 4-potassium sulfoisophthalic acid, 5 -Sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, succinic acid, trimellitic acid, trimesic acid, pyromellitic acid, trimellitic anhydride, anhydrous Pyromellitic acid, phthalic anhydride, p-hydroxy Cisbenzoic acid, trimellitic acid monopotassium salt, aliphatic dicarboxylic acids typified by succinic acid, adipic acid, suberic acid, sebacic acid and dodecanedioic acid or their ester-forming derivatives can be used. Polyhydric hydroxy compounds include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, -Methyl-1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, p-xylylene glycol, bisphenol A-ethylene glycol adduct, diethylene glycol, triethylene glycol , Polyethylene glycol, polypropylene glycol, polytetramethyl N-glycol, polytetramethylene oxide glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate, potassium dimethylolethylsulfonate, potassium dimethylolpropionate, etc. can be used. . One or more compounds may be appropriately selected from these compounds, and a polyester resin may be synthesized by a conventional polycondensation reaction.

  Typical examples of the cyclic lactone compound used as a raw material for the polyester obtained by ring-opening condensation include cyclic monomers such as ε-caprolactone, δ-valerolactone, and β-methyl-δ-valerolactone. It can obtain by superposing | polymerizing by selecting 1 type or more from.

  Furthermore, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid, etc. It can also be synthesized by homopolymerization or copolymerization of the hydroxycarboxylic acid.

  It can be obtained by copolymerizing a cyclic acid anhydride and an oxirane, for example, succinic anhydride and ethylene oxide, propion oxide or the like.

  The polyurethane resin is a polymer compound having a urethane bond in the molecule. Polyurethane resins are usually made by the reaction of polyols and isocyanates. Examples of the polyol include polycarbonate polyols, polyester polyols, polyether polyols, polyolefin polyols, and acrylic polyols. These compounds may be used alone or in combination.

  Polycarbonate polyols are obtained from a polyhydric alcohol and a carbonate compound by a dealcoholization reaction. Examples of the polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentane. Diol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decane Diol, neopentyl glycol, 3-methyl-1,5-pentanediol, 3,3-dimethylol heptane and the like can be mentioned. Examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, and ethylene carbonate. Examples of polycarbonate polyols obtained from these reactions include poly (1,6-hexylene) carbonate, poly (3- And methyl-1,5-pentylene) carbonate.

  Polyester polyols include polycarboxylic acids (malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, fumaric acid, maleic acid, terephthalic acid, isophthalic acid, etc.) or their acid anhydrides. Product and polyhydric alcohol (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol 2-methyl-2-propyl-1 3-propanediol, 1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol 1,9-nonanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-butyl-2-hexyl-1,3-propanediol, cyclohexane Diol, bishydroxymethylcyclohexane, dimethanolbenzene, bishydroxyethoxybenzene, alkyl dialkanolamine, lactone diol, etc.).

  Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polyethylene propylene glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, and the like.

  Among the above polyols, polyester polyols are more preferably used in order to improve the adhesiveness with various adhesive layers.

  Examples of the isocyanate component that can be used in the polyurethane resin that can be used in the present invention include aliphatic, alicyclic, aromatic, or mixed polyisocyanate compounds that are generally used in the production of polyurethane. Specifically, for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-phenylene diisocyanate, 4,4-diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate, tolidine So-called aromatic polyisocyanates such as diisocyanate, xylene diisocyanate, transcyclohexane 1,4-diisocyanate, tetramethylxylene diisocyanate; pentamethylene diisocyanate, hexamethylene diisocyanate, Ptamethylene diisocyanate, 4,4′-dicyclohexylbutane diisocyanate, lysine diisocyanate, isophorone diisocyanate, hydrogenated methylene diphenyl diisocyanate, hydrogenated xylylene diisocyanate, lysine ester triisocyanate, 1,6,11-undecatriisocyanate, 1,8- Examples include diisocyanate-4-isocyanate methyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, and trimethylhexamethylene diisocyanate.

  Examples of the above dimers (uretidione), trimers (isocyanurate), carbodiimide modified products, allophanate modified products, biuret modified products, urea modified products, urethane modified products, and blocked isocyanates thereof. These can be used alone or in combination of two or more.

  A chain extender may be used when synthesizing the polyurethane resin, and the chain extender is not particularly limited as long as it has two or more active groups that react with an isocyanate group. Alternatively, a chain extender having two amino groups can be mainly used.

  Examples of the chain extender having two hydroxyl groups include aliphatic glycols such as ethylene glycol, propylene glycol and butanediol, aromatic glycols such as xylylene glycol and bishydroxyethoxybenzene, and esters such as neopentyl glycol hydroxypivalate. And glycols such as glycols. Examples of the chain extender having two amino groups include aromatic diamines such as tolylenediamine, xylylenediamine, and diphenylmethanediamine, ethylenediamine, propylenediamine, hexanediamine, 2,2-dimethyl-1,3- Propanediamine, 2-methyl-1,5-pentanediamine, trimethylhexanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10- Aliphatic diamines such as decane diamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, dicyclohexylmethanediamine, isoprobilitincyclohexyl-4,4′-diamine, 1,4-diaminocyclohexane, 1 , 3-Bisaminomethylcyclohexane Alicyclic diamines, and the like of.

  The polyamide resin can be obtained by polycondensation of a diamine compound and a dicarboxylic acid compound, polycondensation of an aminocarboxylic acid compound, ring-opening polymerization of lactams, and the like. Examples of the diamine compound, dicarboxylic acid compound, aminocarboxylic acid compound, and lactams used when synthesizing the polyamide in the present invention are given, but the present invention is not limited thereto. Examples of diamine compounds include ethylenediamine, 1,3-propanediamine, 1,2-propanediamine, hexamethylenediamine, octamethylenediamine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, piperazine, 2, Examples include 5-dimethylpiperazine, 4,4′-diaminophenyl ether, 3,3′-diaminodiphenyl sulfone, and xylylenediamine. Examples of dicarboxylic acid compounds include oxalic acid, malonic acid, succinic acid, glutaric acid, dimethylmalonic acid, adipic acid, pimelic acid, α, α-dimethylsuccinic acid, acetone dicarboxylic acid, sebacic acid, 1,9-nonane. Dicarboxylic acid, fumaric acid, maleic acid, itaconic acid, citraconic acid, phthalic acid, isophthalic acid, terephthalic acid, 2-butyl terephthalic acid, tetrachloroterephthalic acid, acetylenedicarboxylic acid, poly (ethylene terephthalate) dicarboxylic acid, 1,2 -Cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, ω-poly (ethyleneoxy) dicarboxylic acid, p-xylylene dicarboxylic acid, and the like. These dicarboxylic acid compounds may be used in the form of alkyl esters of carboxylic acids (for example, dimethyl esters) or acid chlorides of dicarboxylic acids, or acid anhydrides such as maleic anhydride, succinic anhydride, and phthalic anhydride. It may be used in the form of a thing. Examples of aminocarboxylic acids include glycine, alanine, phenylalanine, ω-aminohexanoic acid, ω-aminodecanoic acid, ω-aminoundecanoic acid, anthranilic acid and the like. Examples of monomers (lactams) used for ring-opening polymerization include ω-caprolactam, azetidinone, and pyrrolidone.

  The acrylic resin is a polymer composed of a polymerizable monomer having a carbon-carbon double bond, as typified by acrylic and methacrylic monomers. These may be either a homopolymer or a copolymer. Moreover, the copolymer of these polymers and other polymers (for example, polyester, polyurethane, etc.) is also included. For example, a block copolymer or a graft copolymer. Alternatively, a polymer (possibly a mixture of polymers) obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in a polyester solution or a polyester dispersion is also included. Similarly, a polymer (in some cases, a mixture of polymers) obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in a polyurethane solution or polyurethane dispersion is also included. Similarly, a polymer obtained by polymerizing a polymerizable monomer having a carbon-carbon double bond in another polymer solution or dispersion (in some cases, a polymer mixture) is also included.

  The polymerizable monomer having a carbon-carbon double bond is not particularly limited, but particularly representative compounds include, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, citracone. Various carboxyl group-containing monomers such as acids, and salts thereof; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, monobutyl hydroxyl fumarate, Various hydroxyl group-containing monomers such as monobutylhydroxy itaconate; various monomers such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate ( (Meth) acrylic acid esters; Various nitrogen-containing compounds such as meth) acrylamide, diacetone acrylamide, N-methylolacrylamide or (meth) acrylonitrile; various styrene derivatives such as styrene, α-methylstyrene, divinylbenzene, vinyltoluene, vinyl propionate Various vinyl esters such as: Various silicon-containing polymerizable monomers such as γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, etc .; Phosphorus-containing vinyl monomers; Various such as vinyl chloride and biridene chloride And various conjugated dienes such as butadiene.

The polycarbodiimide compound used in the present invention is a carbodiimide compound having two or more carbodiimide groups in the molecule.
As the polycarbodiimide compound, those produced by various methods can be used. Basically, a conventional method for producing polycarbodiimide (for example, US Pat. No. 2,941,956, Japanese Patent Publication No. 47-33279). , J. 0 rg. Chem. 28, 2069-2075 (1963), Chemical Review 981, Vol. 81 No. 4, p 619-621) can be used.

  Examples of the organic diisocyanate that is a synthetic raw material in the production of the polycarbodiimide compound include aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and mixtures thereof. Specifically, 1,5-naphthalene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2, Mixture of 4-tolylene diisocyanate and 2,6-tolylene diisocyanate, hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone Illustrate isocyanate, dicyclohexylmethane-4,4′-diisocyanate, methylcyclohexane diisocyanate, tetramethylxylylene diisocyanate, 2,6-diisopropylphenyl isocyanate, 1,3,5-triisopropylbenzene-2,4-diisocyanate, etc. Can do.

  Moreover, in the case of the said polycarbodiimide compound, a polymerization reaction can be stopped on the way by cooling etc., and it can control to a suitable polymerization degree. In this case, the terminal is isocyanate. Furthermore, in order to control the degree of polymerization to an appropriate degree, there is a method in which all or part of the remaining terminal isocyanate is sealed using a compound that reacts with the terminal isocyanate of the polycarbodiimide compound, such as monoisocyanate. By controlling the degree of polymerization, compatibility with the polymer and storage stability can be increased, which is preferable in terms of quality improvement.

  Examples of the monoisocyanate for sealing the end of such a polycarbodiimide compound and controlling the degree of polymerization thereof include phenyl isocyanate, tolyl isocyanate, dimethylphenyl isocyanate, cyclohexyl isocyanate, butyl isocyanate, naphthyl isocyanate and the like. be able to.

  Further, the end-capping agent that seals the end of the polycarbodiimide compound and controls the degree of polymerization thereof is not limited to the above-mentioned monoisocyanate, and is an active hydrogen compound that can react with isocyanate, for example, (i) An aliphatic, aromatic or alicyclic compound having an —OH group, methanol, ethanol, phenol, cyclohexanol, N-methylethanolamine, polyethylene glycol monomethyl ether, polypropylene glycol monomethyl ether; (ii) = NH group (Iii) butylamine having a -NH2 group, cyclohexylamine; (iv) succinic acid, benzoic acid, cyclohexane acid having a -COOH group; (v) ethyl mercaptan having a -SH group, allyl mercaptan Compounds with (vi) an epoxy group; thiophenol (vii) acetic anhydride, methyl tetrahydrophthalic anhydride, can be exemplified acid anhydrides such as methylhexahydrophthalic anhydride, and the like.

  The decarboxylation condensation reaction of the organic diisocyanate is carried out in the presence of a suitable carbodiimidization catalyst. Examples of the carbodiimidization catalyst that can be used include organophosphorus compounds, organometallic compounds (general formula M- (OR) 4 [M is titanium (Ti), sodium (Na), potassium (K), vanadium (V), tungsten (W), hafnium (Hf), zirconium (Zr), lead (Pb), manganese (Mn), nickel (Ni), calcium (Ca), barium (Ba), etc., wherein R represents an alkyl group or aryl group having 1 to 20 carbon atoms] is preferred, particularly from the standpoint of activity Phosphorene oxides are preferable for organic phosphorus compounds, and alkoxides of titanium, hafnium, and zirconium are preferable for organic metal compounds.

  Specific examples of the phosphorene oxides include 3-methyl-1-phenyl-2-phospholene-1-oxide, 3-methyl-1-ethyl-2-phospholene-1-oxide, 1,3- Dimethyl-2-phospholene-1-oxide, 1-phenyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, 1-methyl-2-phospholene-1-oxide or a double of these Examples of the bond isomer can be exemplified, and 3-methyl-1-phenyl-2-phospholene-1-oxide which is easily available industrially is particularly preferable.

The polycarbodiimide compound acts as a hydrolysis stabilizer for the resin contained in the adhesive composition for solar battery backsheet of the present invention, but from the viewpoint of safety, stability and compatibility, aliphatic or alicyclic A polycarbodiimide compound synthesized from an aliphatic isocyanate is preferable, and a polycarbodiimide compound derived from isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, or tetramethylxylylene diisocyanate is particularly preferable.
Moreover, as a polymerization degree of a polycarbodiimide compound, 2-200 are preferable, More preferably, it is 2-100.

  The blending amount of the polycarbodiimide compound is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the resin contained in the adhesive composition for solar battery backsheet of the present invention. Preferably, 0.1 to 3 parts by weight is particularly preferable.

  You may make the adhesive composition for solar cell backsheets of this invention contain additives other than a polycarbodiimide compound. Examples of additives that can be added include additives generally used in resin compositions that form films and coating films. For example, leveling agent, colloidal silica, inorganic fine particles such as alumina sol, polymethyl methacrylate organic fine particles, antifoaming agent, anti-sagging agent, silane coupling agent, titanium white, complex oxide pigment, carbon black, organic pigment Pigments such as pigment intermediates, pigment dispersants, phosphorus and phenolic antioxidants, viscosity modifiers, UV stabilizers, metal deactivators, peroxide decomposers, flame retardants, reinforcing agents, plasticizers Lubricants, rust inhibitors, fluorescent brighteners, organic and inorganic ultraviolet absorbers, inorganic heat absorbers, organic and inorganic flame retardants, organic and inorganic antistatic agents, Examples include dehydrating agents such as methyl orthoformate, but the present invention is not limited to such examples. Moreover, you may add hydrolysis-resistant stabilizers other than polycarbodiimide compounds, such as an epoxy resin and a monocarbodiimide compound, in the range which does not impair the effect of this invention.

The back sheet for solar cell of the present invention is obtained by bonding a base material with an adhesive made of an adhesive composition.
Examples of the substrate of the present invention include a polyester substrate selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polycyclohexanedimethanol-terephthalate (PCT), a polycarbonate substrate, Polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), polyethylene tetrafluoroethylene (ETFE), polytetrafluoroethylene (PTFE), tetrafluoroethylene perfluoroalkyl vinyl ether copolymer ( PFA), a fluorine-based substrate selected from tetrafluoroethylene-hexafluoropropylene copolymer (FEP), an acrylic substrate, a cyclic olefin (COC), Polyolefin base materials such as polyethylene (high density polyethylene, low density polyethylene, linear low density polyethylene), polypropylene, polybutene, polyvinyl chloride base materials, polystyrene base materials, polyvinylidene chloride base materials, ethylene-vinyl acetate It is selected from copolymer base materials, polyvinyl alcohol base materials, polyvinyl acetate base materials, acetal base materials, polyamide base materials, polyarylate base materials, and these base materials are the same or different. It may be.
In addition, a plurality of base materials and adhesive layers may be present, and a layer having functionality such as a gas barrier layer may be provided on the intermediate layer or the outer layer of the back sheet.

  Next, a method for manufacturing the backsheet will be described. The back sheet of the present invention uses a known method such as a method in which an adhesive resin composition constituting an adhesive layer is applied to a first substrate, the second substrate is bonded, and cured by heating or the like. Can be manufactured.

  EXAMPLES Hereinafter, although a manufacture example, an Example, and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to the following Example.

The following materials were used as the substrate.
Base material 1: manufactured by Toyobo Co., Ltd., trade name: E-5000 [polyethylene terephthalate (hereinafter referred to as PET) film]

(Synthesis of polycarbodiimide compound)
Synthesis example 1
In a 300 mL three-necked flask, 100 g of 1,3-bis (1-isocyanato-1-methylethyl) benzene (manufactured by CYTEC, hereinafter abbreviated as TMXDI) was added, and 1-phenyl-2-phospholene-1- After adding 2.0 g of oxide and stirring at 180 ° C. for 10 hours under nitrogen bubbling, ethyl acetate (manufactured by Kanto Chemical) was added to obtain polycarbodiimide 1 adjusted to a solid content of 30%. The obtained polycarbodiimide compound had an NCO% of 8.0 and a degree of polymerization of 4.

Synthesis example 2
In a 300 mL three-necked flask, 100 g of TMXDI was added, 2.0 g of 1-phenyl-2-phospholene-1-oxide was added as a catalyst, and the mixture was stirred at 180 ° C. for 10 hours under nitrogen bubbling. The obtained product had an NCO% of 8.0 and a degree of polymerization of 4. After cooling this to 100 ° C., 49.2 g of polyethylene glycol monomethyl ether (molecular weight 300) was added dropwise and reacted at 100 ° C. for 5 hours in a nitrogen atmosphere, and then the peak of the isocyanate group of the polycarbodiimide compound was observed in the IR spectrum. After confirming disappearance, the reaction was stopped, and then ethyl acetate (manufactured by Kanto Chemical) was added to obtain polycarbodiimide 2 adjusted to a solid content of 30%.

Synthesis example 3
In a 300 mL three-necked flask, 100 g of TMXDI was added, 2.0 g of 1-phenyl-2-phospholene-1-oxide was added as a catalyst, and the mixture was stirred at 180 ° C. for 40 hours under nitrogen bubbling. Product) to obtain a polycarbodiimide 3 adjusted to a solid content of 30%. The obtained polycarbodiimide compound had an NCO% of 0.55 and a degree of polymerization of 75.

Synthesis example 4
In a 300 mL three-necked flask, 100 g of TMXDI was added, 2.0 g of 1-phenyl-2-phospholene-1-oxide was added as a catalyst, and the mixture was stirred at 180 ° C. for 40 hours under nitrogen bubbling. The obtained product had an NCO% of 0.55 and a degree of polymerization of 75. After cooling this to 100 ° C., 0.82 g of ethylene glycol monomethyl ether was dropped, and after reacting at 100 ° C. for 5 hours in a nitrogen atmosphere, the peak of the isocyanate group of the polycarbodiimide compound disappeared in the IR spectrum. The polycarbodiimide 4 which confirmed and added ethyl acetate (made by Kanto Chemical) and adjusted to 30% of solid content was obtained.

[Manufacture of adhesive composition]
Adhesive production example 1
As a resin, Mitsui Chemicals, Inc., trade name: Takelac A515 (main agent) and Mitsui Chemicals, Inc., trade name: Takenate A50 (curing agent) are mixed at a mass ratio of 10: 1 and diluted with ethyl acetate. A polyurethane resin adjusted to a solid content of 30% was obtained. 3 parts of polycarbodiimide 1 was added to 100 parts of the polyurethane resin and mixed to obtain an adhesive 1.

Adhesive production examples 2 to 4
In Example 1, adhesives 2 to 4 were obtained in the same manner as in Example 1 except that polycarbodiimide was changed as shown in the table.

Adhesive production example 5
As a resin, Mitsui Chemicals, Inc., trade name: Takelac A515 (main agent) and Mitsui Chemicals, Inc., trade name: Takenate A50 (curing agent) are mixed at a mass ratio of 10: 1 and diluted with ethyl acetate. As a result, a polyurethane resin adjusted to a solid content of 30% was obtained, and this was used as the adhesive 5.

[Preparation of solar cell backsheet]
Example 1
After applying the adhesive 1 to the base material 1 and drying the solvent so that the coating amount after drying is 10 g / m ² , another base material 1 is laminated, and the back sheet for solar cells is formed by the dry laminating method. Then, curing was performed at 60 ° C. for 7 days to obtain a solar cell backsheet of Example 1.

Examples 2-4, Comparative Example 1
In the same manner as in Example 1, solar cell back sheets of Examples 2 to 4 and Comparative Example 1 were obtained using adhesives 2 to 5.

The following measurements were performed and the obtained solar cell backsheet was evaluated.
(Initial adhesion)
The interlayer adhesion of the solar cell module backsheet produced using any one of the adhesives 1 to 15 using a T-type peeling method with an Instron 5582 type universal material testing machine, at a 15 mm width crosshead speed of 300 mm / min. The strength was tested.

[Hydrolysis resistance]
The back sheet having the above-described configuration was evaluated for hydrolysis resistance by an accelerated evaluation test using pressurized steam.
The back sheet having the above configuration is cut to A4 size, set in a high pressure cooker (accelerated evaluation apparatus using pressurized steam), heated in an atmosphere of 105 ° C. for 96 hours, 168 hours or 192 hours, The laminate strength and peel behavior of the sheet were evaluated.
The laminate strength was measured by measuring the strength at a 15 mm width crosshead speed of 300 mm / minute using a T-type peeling method with an Instron 5582 type universal material testing machine, and the laminate strength before the accelerated evaluation test using pressurized steam. The ratio (a value obtained by dividing the laminate strength after the accelerated evaluation test using pressurized steam by the laminate strength before the test and multiplying by 100) was evaluated as the laminate strength retention rate (%).
In addition, the solar cell module backsheet normally requires storage for 2000 hours or more in an atmosphere of 85% relative humidity and 85 ° C. as an accelerated evaluation. On the other hand, according to this method, the time required for accelerated evaluation is shortened, and the physical properties in 2000 hours at a temperature of 85 ° C. and a relative humidity of 85% are the properties when stored at a temperature of 105 ° C. for 168 hours. The equivalent has already been confirmed.

[Evaluation criteria for hydrolysis resistance]
The hydrolysis resistance test results were evaluated according to the following criteria.
○: Retention strength retention of 90% or more and less than 95% (excellent adhesion)
Δ: Retention strength of laminate strength is 80% or more and less than 90% (adhesion is slightly inferior)
X: Retention rate of laminate strength is less than 80% (adhesion is inferior)

  From the results shown in Table 2, the backsheets shown in Examples 1 to 4 are all excellent in hydrolysis resistance even under high temperature and high humidity as compared with the backsheet obtained in Comparative Example 1. I understand that.

Claims (5)

In the adhesive used to bond the substrates constituting the solar cell backsheet,
Ri adhesive is Do from the resin and polycarbodiimide compound,
The resin is at least one selected from polyurethane resin, polyamide resin, acrylic resin, vinyl acetate resin, epoxy resin, polyolefin resin, cyanoacrylate resin, cellulose resin, polyether resin, polyimide resin, amino resin, phenol resin, and silicone resin. An adhesive composition for solar battery backsheet, which is a seed .   The adhesive composition for solar cell backsheets of Claim 1 whose polycarbodiimide compound is a polycarbodiimide compound derived from aliphatic diisocyanate and / or alicyclic diisocyanate.   The adhesive composition for a solar battery back sheet according to claim 2, wherein the aliphatic diisocyanate and the alicyclic diisocyanate are isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and tetramethylxylylene diisocyanate. The resin Gapo polyurethane resin is at least one selected from polyamide resins and acrylic resins, claims 1-3 solar battery backsheet adhesive composition.   The solar cell backsheet which uses the adhesive agent for solar cell backsheets of Claims 1-4 as an adhesive bond layer.