JP2014039040A - Back sheet for solar battery modules - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a back sheet for solar battery modules which is arranged so that the deterioration of the material accompanying the hydrolysis can be prevented not only in an environment of actual use in a solar battery module, but also in an acceleration test in a high-temperature and high-humidity atmosphere to be factored in when making an assessment on the solar battery module, and poor appearance attributed to delamination can be prevented, and which is excellent in weather resistance, especially in hydrolysis resistance, insulation resistance and moisture-barrier property, and which allows an electricity output property to be maintained in the solar battery even after a weathering test, and to provide a solar battery module and a solar battery, each having the back sheet for solar battery modules.SOLUTION: A back sheet for solar battery modules comprises a laminate arranged by gluing together at least two base materials 1 with an acrylic adhesive agent 2. The acrylic adhesive agent includes acrylic polymer produced by polymerization of monomer components including a monomer expressed by the general formula (I): CH=C(R)-CO-OZ (I), where Ris a hydrogen atom or a methyl group, and Z represents a hydrocarbon group having 4-25 carbon atoms.

Description

  The present invention relates to a back sheet for a solar cell module. More specifically, the present invention relates to a solar cell module backsheet excellent in hydrolysis resistance, insulation resistance and moisture barrier properties, a solar cell module having the solar cell module backsheet, and a solar cell having the solar cell module. It relates to batteries. The back sheet for a solar cell module of the present invention is laminated using an adhesive particularly excellent in hydrolysis resistance, insulation resistance and moisture barrier property, prevents deterioration of the material due to hydrolysis, and accompanies delamination. There is no appearance defect, excellent barrier properties as a back sheet, and electrical output characteristics as a solar cell can be maintained even after a weather resistance test. Moreover, since the solar cell module and solar cell of the present invention uses the solar cell module backsheet, it has excellent barrier properties as a backsheet, and has an electrical output characteristic as a solar cell even after a weather resistance test. Can be maintained.

  In recent years, the amount of carbon dioxide emissions has been reduced, while interest from both inside and outside of the global warming issue has increased. Increasing consumption of fossil fuels is said to cause an increase in atmospheric carbon dioxide, and the greenhouse effect increases the temperature of the earth, which is said to have a significant impact on the global environment. Various studies have been conducted to solve this global problem. In particular, photovoltaic power generation is attracting attention from the viewpoint of cleanliness and non-pollution.

  Solar cells used for photovoltaic power generation constitute the heart of a photovoltaic power generation system that directly converts solar light energy into electricity, and consist of single crystal silicon, polycrystalline silicon, or amorphous silicon based semiconductors. Has been. For solar cells, instead of using solar cell elements (cells) as they are, generally several to several tens of solar cell elements are wired in series or in parallel, and the cells are used for a long period of about 20 years. Packaging is applied to protect the unit. The unit incorporated in this package is called a solar cell module. A solar cell module is generally configured by covering a surface exposed to sunlight with a glass surface, filling a gap with a filler made of a thermoplastic resin such as an ethylene-vinyl acetate copolymer, and protecting the back surface with a back sheet. Yes.

  Since the solar cell module is mainly used outdoors, its material and structure are required to have durability and weather resistance. In particular, the backsheet is required to have a weather resistance and a low water vapor transmission rate, that is, excellent moisture barrier properties. These properties are required in order not to adversely affect the output of the module when the filler is peeled off or discolored due to moisture permeation or the wiring is corroded.

  Conventionally, a solar cell backsheet has weather resistance and flame retardancy, and also has good adhesion to an ethylene-vinyl acetate copolymer (hereinafter referred to as EVA) that has been used as a filler for solar cell modules. (For example, refer to Patent Documents 1 and 2). In recent years, a solar battery backsheet using a polyester film such as polyethylene terephthalate with excellent electrical insulation has been developed as a solar battery backsheet, and a solar with an ultraviolet absorber added to improve the weather resistance of the polyester film. Back cover sheet for battery module (for example, see Patent Document 3), solar cell cover material comprising a three-layer laminate of a hydrolysis-resistant resin film, a metal oxide-coated resin film, and a white resin film A back sheet (see, for example, Patent Document 4), a back protective sheet for solar cells (see, for example, Patent Document 5) having a plastic film made of polyester with a cyclic trimer content defined, and a polyethylene terephthalate film were combined. A polyethylene terephthalate comprising a film having a gas barrier layer The molecular weight defined sealing a rear surface of a solar cell film (e.g., see Patent Document 6) have been proposed.

  As described above, since the solar cell needs to maintain its performance for about 20 years, in order to evaluate its durability, for example, it is promoted in a hot and humid atmosphere at 85 ° C. and a relative humidity of 85%. A test is being conducted. In particular, a base material made of a polyester film causes hydrolysis in the atmosphere in this accelerated test, and the strength is remarkably reduced. Therefore, as described in the patent document, in order to suppress the strength reduction Various studies have been conducted.

  However, a new technical problem has been found by improving the weather resistance (hydrolysis resistance) of the film substrate. It is a delamination due to hydrolysis of the adhesive that bonds the film substrate. In general, polyurethane adhesives based on polyester polyols are used as film base materials from the viewpoint of heat resistance and stability. However, since polyester polyol itself has a low molecular weight due to hydrolysis, there is a disadvantage that the adhesive strength is remarkably lowered in the atmosphere of the accelerated test. This defect can also be seen in the fluororesin. When the accelerated test is performed on the fluororesin, floating due to delamination occurs over time, and not only a poor appearance but also a barrier property required for the back sheet is reduced. Therefore, research for sustaining the electrical output characteristics as a solar cell is required.

  Moreover, the resin film which vapor-deposited aluminum foil and the oxide as a gas barrier layer with respect to a water | moisture content or oxygen is used for the back sheet. However, when a resin film on which an aluminum foil or an oxide is deposited is disposed as a back sheet on the back side of the solar cell module, a crack occurs in the resin film covering the aluminum foil or when receiving an impact from the outside. Sometimes, electrical troubles such as short circuit and insulation failure may occur. Moreover, since aluminum foil has the property of being easily corroded even with a small amount of moisture, it cannot be used in an environment with a lot of moisture.

  On the other hand, when an oxide-deposited resin film is disposed as a back sheet on the back side of the solar cell module, the oxide deposition layer is very thin, about 30-120 nm, so there is a slight impact from the outside. Since cracks occur due to friction, sufficient moisture barrier properties cannot be ensured.

  Therefore, in recent years, the development of solar cell module backsheets having excellent weather resistance, particularly hydrolysis resistance, insulation resistance, and moisture barrier properties, and solar cell modules and solar cells having such backsheets for solar cell modules is awaited. It is.

JP-T 8-500214 Japanese translation of PCT publication No. 2002-520820 JP 2001-1111073 A Japanese Patent Laid-Open No. 2002-100788 JP 2002-134771 A JP 2002-26354 A

  The present invention has been made in view of the above-described prior art, and includes not only an environment actually used as a solar cell module but also an accelerated test in a high-temperature and high-humidity atmosphere that is considered when evaluating a solar cell module. In particular, it prevents deterioration of materials due to hydrolysis, prevents appearance defects due to delamination, has excellent weather resistance, especially hydrolysis resistance, insulation resistance and moisture barrier properties, and solar cells even after weather resistance tests An object of the present invention is to provide a back sheet for a solar cell module capable of maintaining the electric output characteristics as, a solar cell module having the back sheet for the solar cell module, and a solar cell.

The present invention
(1) A solar cell module backsheet comprising a laminate in which at least two substrates are bonded together with an acrylic adhesive, wherein the acrylic adhesive is represented by the general formula (I):
^{_{CH 2 = C (R 1)}} -CO-OZ (I)
(In the formula, R ¹ represents a hydrogen atom or a methyl group, and Z represents a hydrocarbon group having 4 to 25 carbon atoms)
A back sheet for a solar cell module comprising an acrylic polymer obtained by polymerizing a monomer component containing a monomer represented by:
(2) The solar cell module backsheet according to (1), wherein the acrylic adhesive forms a crosslinked adhesive layer,
(3) The solar cell module backsheet according to (1) or (2), wherein the acrylic adhesive further contains a curing agent,
(4) The back sheet for a solar cell module according to any one of (1) to (3), wherein the laminate further includes a deposition base material on which an aluminum foil or an oxide is deposited as a gas barrier layer,
(5) A solar cell module comprising the back sheet for a solar cell module according to any one of (1) to (4), and (6) the solar cell module according to (5). The present invention relates to a solar cell.

  The solar cell module backsheet of the present invention is hydrolyzed not only in the environment where it is actually used as a solar cell module, but also in an accelerated test in a high-temperature and high-humidity atmosphere that is considered when evaluating solar cell modules. Prevents deterioration of the materials caused by delamination, prevents appearance defects due to delamination, has excellent weather resistance, especially hydrolysis resistance, insulation resistance, and moisture barrier properties, and has an electrical output characteristic as a solar cell even after a weather resistance test. There is an effect of maintaining. Moreover, since the solar cell module and the solar cell of the present invention have the back sheet for the solar cell module, they have excellent barrier properties as a back sheet and maintain electric output characteristics as a solar cell even after a weather resistance test. Can do.

It is a schematic sectional drawing which shows one embodiment of the solar cell module backsheet of this invention. It is the schematic sectional drawing which interposed the barrier layer as another embodiment of the back seat | sheet for solar cell modules of this invention.

  The solar cell module backsheet of the present invention comprises a laminate in which at least two substrates are bonded together with an acrylic adhesive, and the acrylic adhesive has hydrolysis resistance, insulation resistance and moisture barrier properties. It is characterized by that.

  Here, the hydrolysis resistance is based on the influence of hydrolysis of the adhesive as an index. In the acceleration evaluation using a high pressure cooker (acceleration evaluation apparatus JIS C 60068-2-66 using pressurized steam, etc.), 105 It is mentioned that the initial laminate strength is 80% or more in a state of being stored at 168 hours for 168 hours.

  As the acrylic adhesive, one having hydrolysis resistance, insulation resistance and moisture barrier property is used.

Suitable acrylic adhesives include the general formula (I):
^{_{CH 2 = C (R 1)}} -CO-OZ (I)
(In the formula, R ¹ represents a hydrogen atom or a methyl group, and Z represents a hydrocarbon group having 4 to 25 carbon atoms)
The acrylic adhesive containing the acrylic polymer obtained by polymerizing the monomer component containing the monomer represented by these is mentioned.

  The monomer represented by the general formula (I) may be used alone or in combination of two or more. By using the monomer represented by the general formula (I), a solar cell that forms an adhesive layer excellent in hydrolysis resistance and insulation resistance and maintains electric output characteristics as a solar cell even after a weather resistance test A module backsheet can be provided.

In general formula (I), R < ¹ > is a hydrogen atom or a methyl group. Z is a hydrocarbon group having 4 to 25 carbon atoms. Examples of the hydrocarbon group having 4 to 25 carbon atoms include an alicyclic hydrocarbon group having 4 to 25 carbon atoms such as a cyclohexyl group, a methylcyclohexyl group, and a cyclododecyl group; a butyl group, an isobutyl group, a tert-butyl group, A linear or branched alkyl group having 4 to 25 carbon atoms such as 2-ethylhexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, pentadecyl group, octadecyl group; bornyl group, isobornyl Examples thereof include polycyclic hydrocarbon groups having 7 to 25 carbon atoms such as groups. Among these, an alicyclic hydrocarbon group having 4 to 25 carbon atoms, a branched alkyl group having 4 to 25 carbon atoms, and a straight chain alkyl group having 6 to 25 carbon atoms are preferable, and 6 to 25 carbon atoms are preferable. An alicyclic hydrocarbon group and a branched alkyl group having 4 to 25 carbon atoms are more preferable.

  Examples of the monomer represented by the general formula (I) include cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, tert-butylcyclohexyl (meth) acrylate, isobutyl (meth) acrylate, Examples include tert-butyl (meth) acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate, stearyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. Among these, cyclohexyl (meth) acrylate and tert-butyl (meth) acrylate are preferable from the viewpoint of hydrolysis resistance and insulation resistance.

  In addition, “(meth) acrylate” referred to in the present specification means acrylate and / or methacrylate.

  The content of the monomer represented by the general formula (I) in the monomer component is preferably 10% by mass or more, more preferably 20% by mass or more, from the viewpoint of improving hydrolysis resistance and insulation resistance as an adhesive layer. From the viewpoint of improving the brittleness of the adhesive layer and improving the adhesion, it is preferably 90% by mass or less, more preferably 80% by mass or less, and further preferably 70% by mass or less.

  Examples of other copolymerizable monomers used for the monomer component include, for example, a monomer having a carboxyl group, an acidic phosphate ester monomer, a monomer having a group having active hydrogen, and an ester group having 1 to 3 carbon atoms ( (Meth) acrylic acid ester, monomer having an epoxy group, monomer having a nitrogen atom, monomer having two or more polymerizable double bonds, aromatic monomer, vinyl ester monomer, vinyl ether monomer, etc. The present invention is not limited to such examples. These other copolymerizable monomers may be used alone or in combination of two or more.

  Examples of the monomer having a carboxyl group include (meth) acrylic acid, itaconic acid, maleic anhydride and the like. Examples of the acidic phosphate ester monomers include 2- (meth) acryloyloxyethyl acid phosphate. Examples of the monomer having a group having active hydrogen include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, caprolactone-modified hydroxy (meth) acrylate, and the like. Caprolactone-modified hydroxy (meth) acrylate can be easily obtained commercially, for example, as trade name: Plaxel FM manufactured by Daicel Chemical Industries, Ltd.

  Examples of the (meth) acrylic acid ester having 1 to 3 carbon atoms in the ester group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and isopropyl (meth) acrylate. Examples of the monomer having an epoxy group include glycidyl (meth) acrylate.

  Examples of the monomer having a nitrogen atom include (meth) acrylamide, N, N′-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, imide (meth) acrylate, and the like. Examples of the monomer having two or more polymerizable double bonds include ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, and trimethylolpropane tri (meth). Examples thereof include acrylate and pentaerythritol tetra (meth) acrylate. Examples of the monomer having a halogen atom include vinyl chloride. Examples of the aromatic monomer include styrene and α-methylstyrene. Examples of vinyl ester monomers include vinyl acetate.

  The content of the other copolymerizable monomer in the monomer component is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 30% from the viewpoint of improving the brittleness of the adhesive layer and improving the adhesion. From the viewpoint of improving hydrolysis resistance and insulation resistance as an adhesive layer, it is preferably 90% by mass or less, and more preferably 80% by mass or less.

  The monomer component preferably contains an acrylate having a basic structure of bisarylfluorene from the viewpoint of improving hydrolysis resistance and insulation resistance. An acrylate having a bisarylfluorene as a basic structure is easily commercially available as, for example, Osaka Gas Chemical Co., Ltd., trade names: Ogsol EA-0200, Ogsol EA-0200, Ogsol EA-0500, Ogsol EA-1000, etc. It can be obtained.

Further, cyclohexyl alkyl esters of (meth) acrylic acid, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meta) as disclosed in JP-A-2002-69130. ) Acrylate, tricyclo [5,2,1,0 ^2.6 ] dec-8-yl (meth) acrylate, terpene (meth) acrylate, and the like.

  In addition, the monomer component has a benzotriazole-based, benzophenone-based, or triazine-based UV-absorbing group from the viewpoint of improving the adhesion between the adhesive layer and the deposition substrate on which an aluminum foil or oxide is deposited as a gas barrier layer. Improve adhesion of monomers, monomers with UV-stable groups having sterically hindered piperidine groups, imide (meth) acrylates, morpholino (meth) acrylates, tetrahydrofurfuryl (meth) acrylates, caprolactone-modified hydroxy (meth) acrylates, etc. It is preferable to contain a monomer. These monomers may be used alone or in combination of two or more.

  A monomer having an ultraviolet-absorbing group can be easily obtained commercially as, for example, Otsuka Chemical Co., Ltd., trade name: RUVA93, Osaka Organic Chemical Industry Co., Ltd., trade name: BP-1A. . The monomer which has a UV-stable group can be easily obtained commercially, for example, by Asahi Denka Kogyo Co., Ltd., trade names: ADK STAB LA-82, ADK STAB LA-87 and the like. Caprolactone-modified hydroxy (meth) acrylate can be easily obtained commercially, for example, as trade name: Plaxel FM1D, Plaxel FM2D, Plaxel FM3, Plaxel FA1DM, Plaxel FA2D manufactured by Daicel Chemical Industries, Ltd.

  The monomer component has a UV-absorbing group, a monomer having a sterically hindered piperidine group, a monomer having an UV-stable group, an imide (meth) acrylate, a morpholino (meth) acrylate and a tetrahydrofurfuryl (meth) acrylate. From the viewpoint of sufficiently improving the adhesion with an aluminum foil or a vapor deposition substrate on which an oxide is deposited as a layer, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, and is resistant to hydrolysis and resistance. From the viewpoint of insulation, it is preferably 40% by mass or less, more preferably 30% by mass or less, and still more preferably 20% by mass or less.

  The content of the caprolactone-modified hydroxy (meth) acrylate in the monomer component is preferably 5% by mass or more, more preferably 10%, from the viewpoint of improving the adhesion to a vapor deposition substrate on which an aluminum foil or oxide is vapor-deposited as a gas barrier layer. From the viewpoint of preventing gelation when preparing an acrylic polymer, it is preferably 40% by mass or less, more preferably 30% by mass or less, and still more preferably 20% by mass or less.

  Examples of the method for polymerizing the monomer component include a solution polymerization method, a dispersion polymerization method, a suspension polymerization method, and an emulsion polymerization method, but the present invention is not limited to such examples.

  When the monomer component is polymerized by a solution polymerization method, examples of the solvent include aromatic solvents such as toluene and xylene; alcohol solvents such as isopropyl alcohol and n-butyl alcohol; propylene glycol methyl ether, dipropylene glycol methyl ether, Ether solvents such as ethyl cellosolve and butyl cellosolve; ester solvents such as ethyl acetate, butyl acetate and cellosolve acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diacetone alcohol; amide solvents such as dimethylformamide Although an organic solvent is mentioned, this invention is not limited only to this illustration. These solvents may be used alone or in combination of two or more. The amount of the solvent may be appropriately determined in consideration of the polymerization conditions, the composition of the monomer component, the concentration of the obtained acrylic polymer, and the like.

  When the monomer component is polymerized, a polymerization initiator can be used. Examples of the polymerization initiator include 2,2′-azobis- (2-methylbutyronitrile), tert-butylperoxy-2-ethylhexanoate, 2,2′-azobisisobutyronitrile, benzoyl Although a peroxide, di-tert-butyl peroxide, etc. are mentioned, this invention is not limited only to this illustration. These polymerization initiators may be used alone or in combination of two or more. The amount of the polymerization initiator may be appropriately set according to the desired physical properties of the resulting acrylic polymer, but is usually preferably 0.01 to 50 parts by mass, more preferably 0 per 100 parts by mass of the monomer component. 0.05 to 20 parts by mass.

  The polymerization conditions for polymerizing the monomer components may be set as appropriate according to the polymerization method, and are not particularly limited. The polymerization temperature is preferably room temperature to 200 ° C, more preferably 40 to 140 ° C. What is necessary is just to set reaction time suitably so that the polymerization reaction of a monomer component may be completed.

  An acrylic polymer is obtained by polymerizing the monomer component as described above. The weight average molecular weight of the acrylic polymer is preferably 2,000 to 1,000,000, more preferably 4,000 to 500,000, and still more preferably 5,000 to 300,000. The weight average molecular weight is a value when measured by gel permeation chromatography (GPC) with a polystyrene standard.

  The acrylic adhesive preferably contains an acrylic polymer from the viewpoint of improving the hydrolysis resistance and insulation resistance of the adhesive layer. The acrylic adhesive preferably forms a crosslinked adhesive layer from the viewpoint of improving hydrolysis resistance and insulation resistance.

  The content of the acrylic polymer in the acrylic adhesive (nonvolatile content) is preferably 50% by mass or more from the viewpoint of improving the hydrolysis resistance and adhesion of the adhesive layer, and the hydrolysis resistance of the adhesive layer and From the viewpoint of insulation resistance, it is preferably 100% by mass or less, more preferably 95% by mass or less.

  In addition to the acrylic polymer, the acrylic adhesive can contain other components such as a curing agent and an additive described later.

  The adhesive layer made of an adhesive may be either crosslinked or uncrosslinked, but is preferably crosslinked from the viewpoint of improving hydrolysis resistance and insulation resistance. The adhesive layer is preferably formed by, for example, the adhesive itself being crosslinked by itself, or by being crosslinked by containing a curing agent in the adhesive. When the adhesive layer is formed by containing a curing agent in the adhesive, at least one selected from the group consisting of a polyisocyanate compound and a modified product thereof, an epoxy resin, and an oxazoline group-containing resin is used as the curing agent. Is preferred.

  Examples of the curing agent include (block) polyisocyanate compounds and aminoplast resins, and these may be used alone or in combination of two or more.

  The (block) polyisocyanate compound means a polyisocyanate compound and / or a block polyisocyanate compound.

  Examples of the polyisocyanate compound include compounds having at least two isocyanate groups in the molecule. Examples of the polyisocyanate compound include tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), lysine diisocyanate, trimethylhexamethylene diisocyanate, 1 , 3- (isocyanatomethyl) cyclohexane, 1,5-naphthalene diisocyanate, polyisocyanate such as triphenylmethane triisocyanate; derivatives (modified products) of these polyisocyanates such as adducts, burettes and isocyanurates However, the present invention is not limited to such examples.

  The block polyisocyanate compound is crosslinked when the adhesive is dried by heating, but has a property of improving storage stability at room temperature. The block polyisocyanate compound is usually one in which the isocyanate group of the polyisocyanate compound is blocked with a blocking agent. Examples of the blocking agent include ε-caprolactam, phenol, cresol, oxime, alcohol, and the like, but the present invention is not limited to such examples. Among the block polyisocyanate compounds, a non-yellowing polyisocyanate compound having no isocyanate group directly bonded to an aromatic ring is preferable from the viewpoint of preventing yellowing of the adhesive layer.

  (Block) Polyisocyanate compounds are, for example, manufactured by Sumika Bayer Urethane Co., Ltd., trade names: Death Module N3200, Death Module N3300, Death Module BL3175, Death Module N3400, Death Module N3600, Death Module VPLS2102; Asahi Kasei Corporation ), Trade name: Duranate E-402-90T, etc., and can be easily obtained commercially.

  The amount of the (block) polyisocyanate compound is not particularly limited. For example, the amount of isocyanate groups in the (block) polyisocyanate compound per mole of hydroxyl group in the acrylic polymer is preferably 0.6 moles or more from the viewpoint of improving the hydrolysis resistance and insulation resistance of the adhesive layer. More preferably 0.8 mol or more, from the viewpoint of preventing the unreacted isocyanate group from reacting with moisture in the air to foam or whiten the adhesive layer, preferably 1.4 mol or less, More preferably, it is 1.2 mol or less.

  An aminoplast resin is an addition condensate of a compound having an amino group such as melamine or guanamine with formaldehyde, and is also called an amino resin.

  Examples of aminoplast resins include dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, hexamethylol melamine, fully alkyl methylated melamine, fully alkyl butylated melamine, fully alkyl isobutylated melamine, completely Melamine resins such as alkyl mixed etherified melamine, methylol group methylated melamine, imino group methylated melamine, methylol group mixed etherified melamine, imino group mixed etherified melamine; butylated benzoguanamine, methyl / ethyl mixed alkyl Benzoguanamine, methyl / butyl mixed alkylated benzoguanamine, guanamine resins such as butylated glycoluril, and the like, but the present invention is limited only to such examples. Not to.

  Aminoplast resins are commercially available, for example, as Mitsui Cytec Co., Ltd., trade names: Cymel 1128, Cymel 303, My Coat 506, Cymel 232, Cymel 235, Cymel 771, Cymel 325, Cymel 272, Cymel 254, Cymel 1170, and the like. Can be easily obtained.

  The amount of aminoplast resin is not particularly limited. The mass ratio of the solid content between the acrylic polymer and the aminoplast resin (acrylic polymer / aminoplast resin) is preferably 6/4 or more from the viewpoint of improving the adhesion, and the hydrolysis resistance and adhesion of the adhesive layer From the viewpoint of enhancing the properties, it is preferably 9/1 or less.

  The content of the curing agent in the acrylic adhesive (non-volatile content) varies depending on the type of the curing agent and cannot be determined unconditionally, but usually from the viewpoint of hydrolysis resistance and insulation resistance of the adhesive layer The amount is preferably 5% by mass or more, and preferably 50% by mass or less from the viewpoint of hydrolysis resistance and adhesion of the adhesive layer.

  The acrylic adhesive can be cured under various curing conditions depending on the use of the acrylic adhesive and the type of curing agent used in the acrylic adhesive. Therefore, the acrylic adhesive can be used as a room temperature curable type, a heat curable type, an ultraviolet curable type, or an electron beam curable type. Moreover, there is no limitation in particular in the quantity of a hardening | curing agent, its addition or a dispersion method. For example, when the acrylic polymer has a plurality of hydroxyl groups in one molecule, the amount, addition or dispersion method of the curing agent may be adjusted according to the acrylic polymer.

  The acrylic adhesive may contain a curing catalyst for promoting the crosslinking reaction between the acrylic polymer and the curing agent, if necessary. Although there is no limitation in particular as a curing catalyst, For example, when using a (block) polyisocyanate compound, dibutyltin dilaurate, a tertiary amine, etc. are preferable. Moreover, when using an aminoplast resin, an acidic or basic curing catalyst is preferable.

  The acrylic adhesive may contain, for example, a solvent or an additive. Examples of the solvent include the same organic solvents as described above. Moreover, as an additive, the additive etc. which are generally used for the resin composition which forms a film, a coating film, etc. are mentioned. Examples of additives include leveling agents; inorganic fine particles such as colloidal silica and alumina sol; polymethyl methacrylate organic fine particles; antifoaming agents; sagging inhibitors; silane coupling agents; titanium white, composite oxide pigments, Pigments such as carbon black, organic pigments and pigment intermediates; pigment dispersants; phosphorous and phenolic antioxidants; viscosity modifiers; UV stabilizers; metal deactivators; peroxide decomposing agents; Reinforcing agent; Plasticizer; Lubricant; Rust inhibitor; Fluorescent brightener; Organic and inorganic UV absorbers; Inorganic heat absorber; Organic and inorganic flameproof agent; Organic and inorganic An antistatic agent, such as a dehydrating agent such as methyl orthoformate, and the like. However, the present invention is not limited to such examples.

  In addition, it is preferable to adjust suitably the quantity of a curing catalyst, a solvent, and an additive according to the property requested | required of a contact bonding layer.

  In the present invention, from the viewpoint of improving the adhesion to the base material, the acrylic adhesive includes polyester resin, terpene resin, modified polyolefin resin, EVA, polyvinyl butyral (PVB), silicone resin, vinyl chloride resin, polyurethane. It is preferable to contain a thermoplastic resin such as

  Examples of the polyester resin include Byron [registered trademark, manufactured by Toyobo Co., Ltd.] series (brands: 103, 240, 500, GK110, GK640, etc.), Nichigo Polyester [registered trademark, Nippon Synthetic Chemical Industry Co., Ltd. )] Series (brand: TP-220, TP-235, TP-236, TP-290, etc.). Examples of the terpene-based resin include Clearon [registered trademark, manufactured by Yasuhara Chemical Co., Ltd.] series (brand: M-115, P-115, etc.). Examples of the modified olefinic resin include, for example, Auroren [registered trademark, manufactured by Nippon Paper Chemicals Co., Ltd.] series (brand: 100, 200, 350, S-5189, etc.), Umex [registered trademark, Sanyo Chemical Industries, Ltd.] ] Series (brand: 1001, 1010, 2000, etc.). Examples of EVA include, for example, Mersen [registered trademark, manufactured by Tosoh Corporation] series (brand: H-6051, H-6410, etc.), Smitate [registered trademark, manufactured by Sumitomo Chemical Co., Ltd.] series (brand: KA-31). , KA-42, etc.).

  An acrylic adhesive can be used when bonding the base materials used as a back sheet for solar cell modules.

  Suitable examples of the base material include a polyester base material, a polycarbonate base material, a fluorine base material, and an acrylic base material.

  Examples of the polyester used for the polyester substrate include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polycyclohexanedimethanol terephthalate, etc., and these may be used alone or in combination of two or more. May be.

  Examples of the fluorine-based resin used for the fluorine-based substrate include polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene, polyethylene tetrafluoroethylene, polytetrafluoroethylene, and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. , Tetrafluoroethylene-hexafluoropropylene copolymer, and the like. These may be used alone or in combination of two or more.

  Further, in the present invention, in addition to the above-mentioned base material, a resin such as a polyolefin resin, a polyamide resin, or a polyarylate resin is considered in consideration of heat resistance, strength physical properties, electrical insulation properties, hydrolysis resistance, and the like. The base material which consists of can be used.

  FIG. 1 is a schematic cross-sectional view showing a configuration when the base material is bonded with an acrylic adhesive. FIG. 1 is a schematic cross-sectional view showing one embodiment of a back sheet for a solar cell module of the present invention, and has the simplest structure. The two base materials 1 and 1 are bonded together with an adhesive layer 2 formed of an acrylic adhesive. The base materials 1 and 1 may be base materials made of the same material, or may be base materials made of different materials.

  FIG. 2 is a schematic cross-sectional view with a barrier layer interposed as another embodiment of the solar cell module backsheet of the present invention. In FIG. 2, the adhesive layers 2 and 2 of the acrylic adhesive are formed on one surface of each of the two substrates 1 and 1, and the acrylic adhesive formed on the two substrates 1 and 1 A back sheet for a solar cell module is formed by integrating the two base materials with the gas barrier layer 3 interposed between the adhesive layers 2 and 2.

  Among the back sheet for solar cell module shown in FIG. 1 and the back sheet for solar cell module shown in FIG. 2, the back sheet for solar cell module shown in FIG. It is preferable from the point.

  Examples of the gas barrier layer 3 shown in FIG. 2 include a vapor deposition substrate on which an oxide such as a metal foil, a metal vapor deposition film, and an oxide vapor deposition film is vapor-deposited.

  Examples of the metal foil include an aluminum foil. As a metal vapor deposition film, the aluminum vapor deposition film etc. which vapor-deposited aluminum on the polyester film and the polyolefin-type stretched film are mentioned, for example.

  As the oxide vapor deposition film, for example, a film in which aluminum oxide, silicon dioxide, tin oxide, magnesium oxide, indium oxide, and complex oxides thereof are vapor-deposited on a polyester base material, which is transparent and has oxygen, water vapor, etc. Examples thereof include those having gas barrier properties. In these, the film which vapor-deposited silicon dioxide on the polyester base material and the film which vapor-deposited aluminum oxide on the polyester film are preferable. In the oxide vapor deposition film, the thickness of a suitable oxide vapor deposition layer varies depending on the type and composition of the oxide, but in general, from the viewpoint of forming a uniform oxide vapor deposition layer, preferably 5 nm or more, more preferably Is 10 nm or more, and is preferably 300 nm or less, more preferably 150 nm or less, from the viewpoint of imparting flexibility and preventing cracks from being generated by external stress. Examples of the method for forming an oxide deposition layer include a vacuum deposition method, a thin film formation method such as a sputtering method, an ion plating method, and a plasma vapor deposition method (CVD). However, the present invention is not limited to such examples.

  From the viewpoint of stabilizing and improving the gas barrier property of the back sheet for the solar cell module of the present invention, for example, an undercoat layer made of an acrylic polyol, an isocyanate compound, and a silane compound may be provided on the substrate, and an oxide. An overcoat layer comprising a portion of polyvinyl alcohol or a completely saponified product and a silane compound may be provided on the deposited layer.

  The back sheet for the solar cell module of the present invention is, for example, acrylic based on a method such as gravure coating, roll coating, bar coating, reverse coating on the base material so that the film thickness after drying becomes 0.1 to 20 μm. After the adhesive is applied, it can be produced by bonding another substrate onto the substrate by a method such as dry lamination. At this time, the substrate may be subjected to a surface treatment for improving adhesiveness such as corona treatment, flame treatment, and plasma treatment, if necessary. For example, when a base material made of a fluororesin is used as the base material, it is preferable to perform plasma treatment or the like on the base material. Moreover, not only the said method, For example, you may provide the easily bonding coating layer which consists of a polyester-type resin, a polyurethane-type resin, an acrylic resin, or these mixtures on a base material.

  The acrylic adhesive used in the solar cell module backsheet of the present invention is composed of EVA resin, polyvinyl butyral resin, silicone resin, vinyl chloride resin, polyurethane resin, etc. constituting the solar cell module. It can also be used as an adhesive with the filler layer.

  By using the back sheet for a solar cell module of the present invention, a solar cell module having good hydrolysis resistance, insulation resistance and adhesion, and a good protective effect of the solar cell module can be obtained.

  The solar cell module of the present invention can be easily configured by replacing the back sheet for the solar cell module of the present invention as a back sheet in, for example, a commonly used solar cell module. Moreover, the solar cell of this invention can be easily comprised by replacing a solar cell module with the solar cell module of this invention in the solar cell generally used, for example.

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

The following were used as the substrate or filler.
Base material 1: manufactured by Teijin DuPont Films, trade name: Tetoron U298W [white polyethylene terephthalate (hereinafter referred to as PET) film]
Base material 2: manufactured by Mitsubishi Plastics Co., Ltd., trade name: Tech barrier (silicon dioxide-deposited PET film)
Base material 3: JIS 1N30 soft aluminum foil base material 4: manufactured by Toray Industries, Inc., trade name: Lumirror X10S (heat-resistant oligomer PET film)
Filler: Mitsui Chemicals Fabro Co., Ltd., product number: SC50B (EVA sheet having a thickness of 400 μm)

Synthesis example 1
In a 500 ml flask equipped with a stirrer, a dripping port, a thermometer, a cooling tube and a nitrogen gas inlet, 70 g of ethyl acetate, 70 g of ethyl methacrylate, 10 g of cyclohexyl methacrylate, 10 g of 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate 50 g out of 100 g of 10 g of the monomer mixture was charged and heated to 80 ° C. After reaching 80 ° C., 1 g of 2,2′-azobis- (2-methylbutyronitrile) as a polymerization initiator was put into the flask, heated by self-heating, and refluxed at about 84 ° C. After 5 minutes from the confirmation of the reflux reaction, the remaining 50 g of the monomer mixture, 1 g of 2,2′-azobis- (2-methylbutyronitrile), and 30 g of ethyl acetate were added to the flask over 2 hours. It was dripped continuously. After further heating for 3 hours, a solution in which the nonvolatile content of the acrylic polymer was 50.0% by mass was obtained.

  The weight average molecular weight of the obtained acrylic polymer was 50000. Table 1 shows the composition of the monomer components used for the synthesis of the acrylic polymer and the physical properties of the resulting acrylic polymer.

Synthesis Examples 2-7
In Synthesis Example 1, an acrylic polymer was obtained in the same manner as in Synthesis Example 1, except that the composition of the monomer components used for the synthesis of the acrylic polymer was as shown in Table 1. Table 1 shows the physical properties of the obtained acrylic polymer.

The details of each component shown in Table 1 are as follows.
MMA: methyl methacrylate EMA: ethyl methacrylate CHMA: cyclohexyl methacrylate TBMA: tert-butyl methacrylate 2EHA: 2-ethylhexyl acrylate HEA: 2-hydroxyethyl acrylate HEMA: 2-hydroxyethyl methacrylate FM1: manufactured by Daicel Chemical Industries, Ltd., trade name : Plaxel FM-1
MMA: Methacrylic acid RUVA93: 2- (2′-hydroxy-5′-methacryloyloxyethylphenyl) -2H-benzotriazole [trade name: RUVA93 manufactured by Otsuka Chemical Co., Ltd.]
LA82: Asahi Denka Kogyo Co., Ltd., trade name: ADK STAB LA82
Polymerization initiator: 2,2′-azobis (2-methylbutyronitrile)

Example 1
8 parts by mass of a polyisocyanate curing agent (manufactured by Sumika Bayer Urethane Co., Ltd., trade name: Desmodur N3200) with respect to 100 parts by mass of the acrylic polymer obtained in Synthesis Example 1 is placed in a container, and is further nonvolatiled with toluene. The adhesive 1 was obtained by diluting until it became a 20 mass% solution.

Examples 2-7
In Example 1, adhesives 2 to 7 were obtained in the same manner as in Example 1 except that the composition of the adhesive was changed as shown in Table 2.

Comparative Example 1
As a urethane-based adhesive, Mitsui Takeda Chemical Co., Ltd., trade name: Takelac A511 (main agent) and Mitsui Takeda Chemical Co., Ltd., trade name: A50 (curing agent) are mixed at a mass ratio of 10: 1. An adhesive 8 was obtained.

Comparative Example 2
In Example 1, an adhesive 9 was obtained in the same manner as in Example 1 except that the composition of the adhesive was changed as shown in Table 2.

The details of each component shown in Table 2 are as follows.
Saturated polyester: manufactured by Toyobo Co., Ltd., trade name: Byron 240
Curing agent A: Isocyanate curing agent [manufactured by Sumika Bayer Urethane Co., Ltd., trade name: Desmodur N3200]
Curing agent B: Oxazoline polymer (copolymer comprising 50% by mass of 2-isopropenyl-2-oxazoline, 20% by mass of methyl methacrylate and 30% by mass of butyl acrylate)

Production Example 1 [Preparation of Back Sheet for Solar Cell Module]
Using any one of adhesives 1 to 9, it was applied to base materials 1 to 3 so that the coating amount after drying was 5 g / m ^2, and each base material was laminated by a dry laminating method. After producing the back sheet for aging, it cured at 50 degreeC for 5 days. The specific structure of the obtained back sheet is as the following structures 1 to 3.

Configuration 1: From the filling layer (EVA) side, base material 2 / “adhesive” / base material 1
Configuration 2: From the filling layer (EVA) side, base material 1 / adhesive / base material 2 / “adhesive” / base material 1
Configuration 3: From the filling layer (EVA) side, base material 1 / adhesive / base material 3 / adhesive / base material 1
In configurations 1 and 2, “adhesive” refers to the adhesive on the side in contact with the vapor deposition layer.

  Next, the physical properties of the backsheet having any one of configurations 1 to 3 were examined by the following method. The results are shown in Table 3.

[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.

  Laminate strength was measured using a T-type peeling method with Tensilon, measuring strength at a 15 mm width crosshead speed of 300 mm / min, and the ratio to the laminate strength before accelerated evaluation test using pressurized steam (accelerated using pressurized steam) The laminate strength after the evaluation test was divided by the laminate strength before the test and multiplied by 100), and the laminate strength retention rate (%) was evaluated.

  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)
A: Laminate strength retention of 95% or more (excellent adhesion)
○: 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)

[Insulation resistance]
In the same manner as the hydrolysis resistance, the backsheets of the constitutions 1 to 3 were evaluated by an accelerated evaluation test using pressurized steam. The back sheet was cut to A4 size, set in a high pressure cooker (accelerated evaluation device using pressurized steam), heated in an atmosphere of 105 ° C. for 168 hours or after 192 hours, JIS-C2110: The strength of dielectric breakdown of each backsheet was measured in accordance with the test method of “Dielectric breakdown strength” defined in No. 94 (Test Method for Dielectric Strength of Solid Electrical Insulating Material).

  Ratio to dielectric breakdown strength before accelerated evaluation test using pressurized steam (dielectric breakdown strength after accelerated evaluation test using pressurized steam is divided by dielectric breakdown strength before the test, 100 Value) was evaluated by the retention rate (%) of the strength of dielectric breakdown.

(Evaluation criteria)
A: Retention rate of dielectric breakdown strength is 95% or more (very good)
○: Retention rate of dielectric breakdown strength is 90% or more and less than 95% (excellent)
Δ: Retention rate of dielectric breakdown strength is 80% or more and less than 90% (slightly inferior)
X: Retention rate of dielectric breakdown strength is less than 80% (inferior)

The test conditions are as shown below.
a) Test voltage power supply frequency: 60 Hz
b) Test voltage rise rate: 1 kV / s
c) Test medium: Insulating oil (mineral oil)
d) Test atmosphere: Air temperature is 25 ° C and relative humidity is 62%

The configuration of the electrode is as follows.
A) Upper electrode: sphere with a diameter of 20 mm b) Lower electrode: disk with a diameter of 25 mm c) Electrode load: 500 g

[Moisture barrier properties]
According to JIS Z0208 “moisture-proof packaging material moisture permeability test method (cup method)”, the ratio of the backsheet having the above-described configuration to the water vapor permeability before the accelerated evaluation test using the pressurized steam before and after the accelerated evaluation test ( The water vapor transmission rate after 168 hours of the accelerated evaluation test using pressurized steam was divided by the water vapor transmission rate before the test and multiplied by 100) to evaluate the water vapor transmission rate retention rate (%).

(Evaluation criteria)
A: Retention rate of water vapor transmission rate is 95% or more (very good)
○: Retention rate of water vapor transmission rate is 90% or more and less than 95% (excellent)
Δ: Retention rate of water vapor transmission rate is 80% or more and less than 90% (slightly inferior)
X: Retention rate of water vapor transmission rate is less than 80% (inferior)

  From the results shown in Table 3, the backsheets obtained in Examples 1 to 7 were all resistant to high-humidity and accelerated evaluation as compared with the backsheets obtained in Comparative Examples 1 and 2. It turns out that it is excellent in hydrolyzability, insulation resistance, and moisture barrier property.

Example 8
The adhesive 2 was applied to the substrate 1 so that the coating amount after drying was 3 g / m ² and dried in the air at 100 ° C. for 1 minute to form an easy-adhesion coat layer.

Next, the base material 1, the base material 2, and the base material 4 on which the easy adhesion coat layer is formed are adjusted so that the coating amount after drying is 5 g / m ^2, and the adhesive 1 is used for easy adjustment. Back substrate for solar cell module by laminating each base material by dry laminating method in the structure of base material 1 / adhesive / base material 2 / “adhesive” / base material 4 so that the adhesive coat layer is on the outside After curing, curing was performed at 50 ° C. for 5 days. The “adhesive” refers to an adhesive on the side in contact with the vapor deposition layer.

Production Example 2 [Production of Easy Adhesion Evaluation Sample]
Two sheets of the back sheet having the above-described configuration cut to a width of 60 mm and a length of 150 mm, and an EVA sheet (manufactured by Mitsui Chemicals Fabro Co., Ltd., product number: SC50B, thickness: 400 μm) were cut to a width of 60 mm and a length of 60 mm. I prepared one thing.

  The EVA sheet was placed so as to be positioned at the center of the back sheet cut as described above, and was laminated so that the easy-adhesion coat layer was in contact with the EVA side. Next, the obtained laminate was evacuated at 130 ° C. for 5 minutes and stored in an oven heated to 150 ° C. for 30 minutes to proceed the crosslinking reaction.

Production Example 3 [Production of Sample for Evaluation of Electrical Characteristics of Solar Cell]
A standard cure type EVA sheet was used as a filler for the solar cell module. The solar cell used was polycrystalline silicon. A cell sandwiched between EVA sheets of the same size (manufactured by Mitsui Chemicals Fabro Co., Ltd., product number: SC50B, thickness: 400 μm) is placed on an A4 size tempered glass, and the back obtained in Example 8 is further placed thereon. The sheet was provided such that the easy-adhesion coat layer was in contact with the EVA side. After evacuation at 130 ° C. for 5 minutes, the product was stored in an oven heated to 150 ° C. for 30 minutes to allow the crosslinking reaction to proceed. After that, an aluminum frame was used for the framework.

Next, the physical properties of the backsheet were examined by the following method. The results are shown in Table 4.
[Evaluation of easy adhesion]
For easy adhesion, the unadhered portion of the backsheet is placed on the upper and lower clips of a tensile tester (manufactured by Tester Sangyo Co., Ltd.) in an atmosphere of 23 ° C. and 65% relative humidity. The peeling strength at a crosshead speed of 100 mm / min with a width of 10 mm was measured using a T-type peeling method by sandwiching and autographing, and evaluated based on the following evaluation criteria.
Further, the sample for evaluation of easy adhesion was tested for 1000 hours in an atmosphere at 85 ° C. and a relative humidity of 85%, and peel strength was evaluated under the same conditions as described above.

(Evaluation criteria)
A: 20 N / 10 mm or more (excellent adhesiveness)
A: 10 N / 10 mm or more and less than 20 N / 10 mm (adhesiveness is good)
Δ: 5 N / 10 mm or more and less than 10 N / 10 mm (adhesiveness is slightly good)
X: Less than 5 N / 10 mm (adhesiveness is poor)

〔blocking〕
Two back sheets are stacked in the direction in which the easy-adhesion coat layer faces do not face each other, that is, in the order of easy-adhesion coat layer / base material layer / easy-adhesion coat layer / base material layer, so that the base material layer comes into contact with the metal plate Then, a rectangular parallelepiped metal weight having a bottom surface of 3 cm × 4 cm was placed on two sheets and left in an atmosphere of 50 ° C. for 65 hours. Thereafter, the weight was removed, and each of the two sheets was pulled in the opposing direction along the plane (corresponding to the major axis direction of the bottom surface of the weight), and the shear stress was measured.

  When blocking does not occur, the shear stress is 0, and the greater the blocking, the greater the shear stress. If the shear stress in this measurement method is less than 0.49 N, there is no practical problem. The evaluation criteria are shown below.

(Evaluation criteria)
◯: Shear stress is less than 0.49N ×: Shear stress is 0.49N or more

[Electrical characteristics of solar cells]
The glass surface of the sample for evaluating the electrical characteristics of the solar cell was placed as the light incident side, and an eye super UV tester [manufactured by Iwasaki Electric Co., Ltd., product number: SUV-W151] was used, and the temperature was 60 ° C. at 100 mW / cm ^2. The test was performed for 100 hours, 150 hours, or 200 hours at a humidity of 50%, and the rate of change in the maximum output before and after the test was measured and evaluated based on the following evaluation criteria.
The electrical output characteristics of the solar cell were measured according to JIS C8913. Further, it was visually observed whether or not the appearance of the back sheet after the test was free from floating.

(Evaluation criteria)
○: Change rate of maximum output is 95% or more △: Change rate of maximum output is 90% or more and less than 95% ×: Change rate of maximum output is less than 90%

Example 9
In Example 8, a back sheet for a solar cell module was prepared in the same manner as in Example 8 except that the adhesive 4 was used instead of the adhesive 2, and the physical properties were evaluated in the same manner as in Example 8. . The results are shown in Table 4.

Example 10
In Example 8, except that the adhesive 5 was used instead of the adhesive 2, a solar cell module backsheet was prepared in the same manner as in Example 8, and the physical properties were evaluated in the same manner as in Example 8. . The results are shown in Table 4.

Comparative Example 3
In Example 8, a solar cell module backsheet was prepared in the same manner as in Example 8 except that the adhesive 8 was used instead of the adhesive 2, and the physical properties were evaluated in the same manner as in Example 8. . The results are shown in Table 4.

Comparative Example 4
In Example 8, except that the adhesive 9 was used instead of the adhesive 2, a solar cell module backsheet was prepared in the same manner as in Example 8, and the physical properties were evaluated in the same manner as in Example 8. . The results are shown in Table 4.

  From the results shown in Table 4, the back sheets for solar cell modules obtained in Examples 8 to 10 are all easy to compare with the back sheets for solar cell modules obtained in Comparative Examples 3 to 4. It turns out that it is excellent in all of adhesiveness, blocking property, an electrical property, and the external appearance of a backsheet.

  From the above results, the back sheet for solar cell module obtained in each example is excellent in barrier characteristics as a back sheet, and can maintain electric output characteristics as a solar cell even after a weather resistance test. Since it can do, it turns out that it can be used conveniently for a solar cell module and a solar cell.

  The back sheet for the solar cell module having the configuration of the present invention is hydrolyzed not only in the environment actually used as the solar cell module, but also in the accelerated evaluation under the high temperature and high humidity considered when evaluating the solar cell module. As the solar cell module and the solar cell are maintained, the deterioration of the materials caused by the delamination is maintained, and not only the poor appearance due to the delamination, but also the barrier sheet as the back sheet and the electrical output characteristics as the solar cell are maintained after the weather resistance test. Can be suitably used. Moreover, since the solar cell module and the solar cell of the present invention have the back sheet for the solar cell module, they have excellent barrier properties as a back sheet and maintain electric output characteristics as a solar cell even after a weather resistance test. Can do.

1: Base material 2: Adhesive layer of acrylic adhesive 3: Barrier layer

Claims (6)

A solar cell module backsheet comprising a laminate in which at least two substrates are bonded together with an acrylic adhesive, wherein the acrylic adhesive is represented by the general formula (I):
^{_{CH 2 = C (R 1)}} -CO-OZ (I)
(In the formula, R ¹ represents a hydrogen atom or a methyl group, and Z represents a hydrocarbon group having 4 to 25 carbon atoms)
A back sheet for a solar cell module, comprising an acrylic polymer obtained by polymerizing a monomer component containing a monomer represented by:   The solar cell module backsheet according to claim 1, wherein the acrylic adhesive forms a crosslinked adhesive layer.   The solar cell module backsheet according to claim 1 or 2, wherein the acrylic adhesive further contains a curing agent.   The back sheet for a solar cell module according to any one of claims 1 to 3, wherein the laminate further comprises a vapor deposition substrate on which an aluminum foil or an oxide is vapor-deposited as a gas barrier layer.   It has a solar cell module backsheet in any one of Claims 1-4, The solar cell module characterized by the above-mentioned.   A solar cell comprising the solar cell module according to claim 5.

Images