JP2010263193A - Back sheet for solar cell module - Google Patents

Abstract

Filling used in solar cells not only in environments actually used as solar cells but also in accelerated tests in high-temperature and high-humidity atmospheres that are considered when evaluating solar cell modules Provided are a back sheet for a solar cell module that has excellent adhesion and weather resistance to materials, maintains electrical output characteristics, and is unlikely to cause poor appearance of the back sheet, a solar cell module having the back sheet for the solar cell module, and a solar cell To do.
On a surface to be bonded to a filler constituting a solar cell module, a general formula (I):
^{_{CH 2 = C (R 1)}} -CO-OZ (I)
(Wherein 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, wherein an adhesive layer made of an acrylic adhesive containing an acrylic polymer obtained by polymerizing a monomer component containing a monomer represented by formula (1) is formed.
[Selection] Figure 1

Description

  The present invention relates to a back sheet for a solar cell module. More specifically, the present invention relates to a back sheet for a solar cell module excellent in adhesiveness, weather resistance, electrical output characteristics and appearance of the back sheet, a solar cell module having the back sheet for the solar cell module, and the solar cell module. It has a solar cell.

  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. Furthermore, since it is necessary to maintain the performance of a solar cell for about 20 years, in order to evaluate its durability, for example, an accelerated test is performed in a high-temperature and high-humidity atmosphere at 85 ° C. and a relative humidity of 85%. It is.

  Conventionally, an ethylene-vinyl acetate copolymer (hereinafter referred to as EVA) is used as a filler because the solar cell backsheet has weather resistance and flame retardancy (see, for example, Patent Documents 1 and 2). ). Moreover, since it is excellent in electrical insulation as a solar cell backsheet, polyester films, such as a polyethylene terephthalate, are used (for example, refer patent documents 3-6).

  However, the polyester film used for the solar battery back sheet and EVA used as a filler are excellent in adhesion at the time of production of the solar cell, but the disadvantage that the adhesion decreases with the passage of time. There is.

  Therefore, in recent years, it is used not only in an environment actually used as a solar cell but also in a solar cell even when an accelerated test is performed in a high-temperature and high-humidity atmosphere studied when evaluating a solar cell module. It is desired to develop a back sheet for a solar cell module that is excellent in adhesion to a filler and weather resistance, maintains electric output characteristics, and does not easily cause an appearance defect of the back sheet.

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 not only an environment actually used as a solar cell, but also an accelerated test in a high-temperature and high-humidity atmosphere that is being considered when evaluating a solar cell module. Back sheet for solar cell module that is excellent in adhesion and weather resistance to fillers used in solar cells, maintains electrical output characteristics, and does not easily cause poor appearance of the back sheet It aims at providing the solar cell module and solar cell which have a back sheet for modules.

The present invention
(1) A back sheet used for a solar cell module, on a surface to be bonded to a filler constituting the solar cell module, the general formula (I):
^{_{CH 2 = C (R 1)}} -CO-OZ (I)
(Wherein 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, wherein an adhesive layer made of an acrylic adhesive containing 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 further contains a curing agent,
(3) The solar cell module backsheet according to (2), wherein the curing agent is at least one selected from the group consisting of (block) polyisocyanate compounds, epoxy resins, and oxazoline group-containing resins,
(4) The solar cell module having the solar cell module backsheet according to any one of (1) to (3), and (5) the solar cell module according to (4). The present invention relates to a solar cell.

  The back sheet for a solar cell module of the present invention is a case where not only the environment actually used as a solar cell but also an accelerated test in a high-temperature and high-humidity atmosphere studied when evaluating the solar cell module. In addition, it has excellent adhesion and weather resistance to the filler used in the solar cell, maintains the electric output characteristics, and has an excellent effect of hardly causing the appearance failure of the back sheet.

  Since the solar cell module and the solar cell of the present invention have the back sheet for the solar cell module, not only the environment actually used as a solar cell but also a high-temperature and high-humidity atmosphere considered when evaluating the solar cell module Even when an accelerated test is performed inside, it has excellent adhesion and weather resistance to fillers used in solar cells, maintains electrical output characteristics, and does not easily cause poor appearance of the backsheet. Play.

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 has a general formula (I) on the surface to be bonded to the filler constituting the solar cell module:
^{_{CH 2 = C (R 1)}} -CO-OZ (I)
(Wherein R ¹ represents a hydrogen atom or a methyl group, and Z represents a hydrocarbon group having 4 to 25 carbon atoms)
The adhesive layer which consists of an acrylic adhesive containing the acrylic polymer formed by polymerizing the monomer component containing the monomer represented by these is characterized by the above-mentioned.

  In the present invention, since the monomer represented by the general formula (I) is contained in the monomer component, not only the environment actually used as a solar cell but also a high temperature studied when evaluating a solar cell module. Even when an accelerated test is performed in a humid atmosphere, it has excellent adhesion and weather resistance to fillers used in solar cells, maintains electrical output characteristics, and is unlikely to cause poor appearance of the backsheet. The effect is played. The monomer represented by the general formula (I) may be used alone or in combination of two or more.

In the 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; an n-butyl group, an isobutyl group, and a tert-butyl group. A linear or branched alkyl group having 4 to 25 carbon atoms such as a group, 2-ethylhexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, pentadecyl group, octadecyl group; Examples thereof include polycyclic hydrocarbon groups having 7 to 25 carbon atoms such as bornyl group and isobornyl group. In these, a C4-C25 alicyclic hydrocarbon group, a C4-C25 branched alkyl group, and a C6-C25 linear alkyl group are preferable, C6-C25 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.

  As used herein, “(meth) acryl” means “acryl” and / or “methacryl”.

  The content of the monomer represented by the general formula (I) in the monomer component is not only an environment actually used as a solar cell, but also an accelerated test in a high-temperature and high-humidity atmosphere studied when evaluating a solar cell module. From the viewpoint of excellent adhesion and weather resistance to fillers used in solar cells, maintaining electrical output characteristics, and reducing the appearance of the back sheet, it is preferably 3% by mass. Above, more preferably 5% by mass or more, further preferably 10% by mass or more, particularly preferably 20% by mass or more, which improves the brittleness of the adhesive layer and improves the adhesiveness to the filler used in the solar cell. From the viewpoint, it is preferably 95% by mass or less, more preferably 90% by mass or less, and still more preferably 85% 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 ester, monomer having epoxy group, monomer having nitrogen atom, monomer having two or more polymerizable double bonds, aromatic monomer, monomer having halogen atom, vinyl ester monomer, vinyl ether monomer However, 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 hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate.

  Examples of the (meth) acrylic acid ester having 1 to 3 carbon atoms in the ester group include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and the like. . 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. Examples of vinyl ether monomers include butyl vinyl ether and cyclohexyl vinyl ether.

  The content of the other copolymerizable monomer in the monomer component is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15%, from the viewpoint of improving the adhesion to the filler used in the solar cell. Even if it is a case where an accelerated test is performed in a high-temperature and high-humidity atmosphere, which is considered when evaluating a solar cell module, not only in an environment actually used as a solar cell. From the standpoint of excellent adhesion and weather resistance to the filler used, maintaining electrical output characteristics, and reducing the appearance of the back sheet, it is preferably 97% by mass or less, more preferably 95% by mass or less, and still more preferably Is 90% by mass or less, particularly 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 commercially easily 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. ) acrylates, may also tricyclo [5,2,1,0 ^2.6] dec-8-yl (meth) acrylate and terpene-based (meth) the use of such acrylate.

  In addition, the monomer component further includes a benzotriazole-based compound such as 2- (2′-hydroxy-5′-methacryloyloxyethylphenyl) -2H-benzotriazole from the viewpoint of improving adhesion to a filler used in solar cells. A monomer having an ultraviolet absorbing group such as a monomer having an ultraviolet absorbing group, a monomer having a benzophenone ultraviolet absorbing group, a monomer having a triazine ultraviolet absorbing group; a monomer having an ultraviolet stable group; It is preferable to contain monomers that improve adhesion such as (meth) acrylate, morpholino (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, and caprolactone-modified hydroxy (meth) acrylate. 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. . Monomers having a UV-stable group can be easily obtained commercially as, for example, Adeka Stables such as ADK STAB LA-82 and ADK STAB LA-87 manufactured by Asahi Denka Kogyo Co., Ltd. Caprolactone-modified hydroxy (meth) acrylate can be easily obtained commercially, for example, as trade name: Plaxel FM1, Plaxel FM1D, Plaxel FM2D, Plaxel FM3, Plaxel FA1DM, Plaxel FA2D, manufactured by Daicel Chemical Industries, Ltd. it can.

  The monomer component has a UV-absorbing group monomer, a UV-stable group monomer, imide (meth) acrylate, morpholino (meth) acrylate, and tetrahydrofurfuryl (meth) acrylate content of filler used in solar cells From the viewpoint of improving the adhesion to the resin, preferably 0.5% by mass or more, more preferably 1% by mass or more, and from the viewpoint of enhancing hydrolysis resistance and insulation resistance, preferably 40% by mass or less, more preferably Is 30% by mass or less, more preferably 20% by mass or less.

  The content of caprolactone-modified hydroxy (meth) acrylate in the monomer component is preferably 5% by mass or more, more preferably 10% by mass or more, from the viewpoint of improving the adhesiveness to the filler used in the solar cell. From the viewpoint of preventing gelation when preparing the 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 (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile), tert-butylperoxy-2-ethylhexano And 2,2′-azobisisobutyronitrile, benzoyl peroxide, di-tert-butyl peroxide, and the like, but the present invention is not limited to such examples. 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 2000 to 1 million, more preferably 4000 to 500,000, and still more preferably 5000 to 300,000. The weight average molecular weight is a value when measured by gel permeation chromatography (GPC) with a polystyrene standard.

  In addition, the hydroxyl value of the acrylic polymer is not only the environment actually used as a solar cell, but also when a accelerated test is performed in a high-temperature and high-humidity atmosphere studied when evaluating a solar cell module. From the viewpoint of improving the adhesiveness to the filler used in the solar cell, it is preferably 5 to 140 mgKOH / g.

  Acrylic adhesives can be applied not only to the environment where solar cells are actually used, but also to solar cells, even when performing accelerated tests in high-temperature and high-humidity atmospheres that are considered when evaluating solar cell modules. The acrylic polymer is contained from the viewpoints of excellent adhesion and weather resistance to the filler used, maintaining electrical output characteristics, and reducing the appearance of the back sheet.

  The content of acrylic polymer in the acrylic adhesive (non-volatile content) is not only the environment where it is actually used as a solar cell, but also an accelerated test in a high-temperature and high-humidity atmosphere that is considered when evaluating solar cell modules. Even if it is carried out, it is preferably 50% by mass or more from the viewpoint of excellent adhesion and weather resistance to the filler used in the solar cell, maintaining electrical output characteristics, and less likely to cause poor appearance of the backsheet. It is. The non-volatile content of the acrylic adhesive may be composed only of an acrylic polymer, but from the viewpoint of improving the hydrolysis resistance and insulation resistance of the adhesive layer, the acrylic polymer in the acrylic adhesive (non-volatile content) The content of is preferably 95% by mass or less.

  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 may be formed, for example, by independently crosslinking the adhesive itself, or may be formed by containing a curing agent in the adhesive and crosslinking the adhesive with the curing agent.

  Examples of the curing agent include (block) polyisocyanate compounds, epoxy resins, oxazoline group-containing resins, aminoplast resins, and the like. These may be used alone or in combination of two or more. Among these, from the viewpoints of curability and weather resistance, at least one selected from the group consisting of (block) polyisocyanate compounds, epoxy resins, and oxazoline group-containing resins is preferred, and (block) polyisocyanate compounds are more preferred. preferable.

  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. Specific 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, Polyisocyanates such as 1,3-bis (isocyanatomethyl) cyclohexane, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate; modified polyisocyanates such as adducts, burettes and isocyanurates of these polyisocyanates (Derivatives) and the like can be mentioned, but the present invention is not limited to such examples.

  The block polyisocyanate compound crosslinks the adhesive by heating, but has properties and adhesiveness that improve storage stability at room temperature. In addition, the block polyisocyanate compound is not only used in an environment actually used as a solar cell, but also in a case where an accelerated test is performed in a high-temperature and high-humidity atmosphere studied when evaluating a solar cell module. It is further excellent in adhesion to the filler used in the battery. 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, Sumidur BL3575MPA / X: manufactured by Asahi Kasei Chemicals Co., Ltd., trade names: Duranate E-402-90T, Duranate TPA-B80E, Duranate MF-B60X, Duranate MF-K60X, etc. 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, and preferably 1.4 mol from the viewpoint of preventing the unreacted isocyanate group from reacting with moisture in the air to cause the adhesive layer to foam or whiten. Below, more preferably 1.2 mol or less.

  Examples of the epoxy resin include Japan Epoxy Resin Co., Ltd., trade names: Epicoat 828, Epicoat 1001X70, Epicoat 815; Asahi Denka Kogyo Co., Ltd., trade name: Adeka Resin EP-4100. Is not limited to such examples.

  Examples of the oxazoline group-containing resin include those manufactured by Nippon Shokubai Co., Ltd., trade names: Epocross K-2000 series, Epocross WS-500, Epocross WS-700, etc., but the present invention is limited to such examples. It is not something.

  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 (acrylic polymer / aminoplast resin) of the solid content of the acrylic polymer and the aminoplast resin is preferably 6/4 or more from the viewpoint of improving the adhesiveness to the filler used in the solar cell, From the viewpoint of improving the hydrolysis resistance and adhesion of the adhesive layer, it is preferably 9/1 or less.

  Since the amount of the curing agent varies depending on the type of the curing agent and the like, it cannot be determined unconditionally. Usually, however, the hydrolysis resistance and insulation resistance of the adhesive layer are based on 100 parts by mass of the acrylic polymer. From the viewpoint of improving the adhesiveness to the filler used in the solar cell, preferably 60 parts by mass or less, more preferably 50 parts by mass or less, preferably 1 part by mass or more, more preferably 3 parts by mass or more. More preferably, it is 30 mass parts or less.

  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. 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 method, a dispersion method, etc. For example, when the acrylic polymer has a plurality of hydroxyl groups in one molecule, the amount of the curing agent may be adjusted according to the acrylic polymer, or an addition method or a dispersion method may be selected.

  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. Further, when an aminoplast resin is used, an acidic or basic curing catalyst is preferable.

  The acrylic adhesive may contain 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. Specific examples of additives include leveling agents; inorganic fine particles such as colloidal silica and alumina sol; organic fine particles based on polymethyl methacrylate; antifoaming agents; anti-sagging agents; silane coupling agents; titanium white, complex oxide pigments Pigment dispersants; Phosphorus antioxidants, antioxidants such as phenolic antioxidants; viscosity modifiers; UV stabilizers; metal deactivators; Flame retardants; Reinforcers; Plasticizers; Lubricants; Rust preventives; Fluorescent brighteners; Organic and inorganic UV absorbers, inorganic heat absorbers; Organic and inorganic barriers Examples include flame retardants; organic and inorganic antistatic agents; and dehydrating agents such as methyl orthoformate, but the present invention is not limited to such examples.

  Note that the amounts of the curing catalyst, the solvent, and the additive vary depending on the type of the curing catalyst, and cannot be determined unconditionally. Therefore, it is preferable to appropriately adjust according to the properties required for the adhesive layer.

  In the present invention, from the viewpoint of improving the adhesiveness to the filler used in the solar cell, the acrylic adhesive includes, for example, polyester resin, modified polyolefin resin, EVA, polyvinyl butyral (PVB), silicone resin, chloride It is preferable to contain a thermoplastic resin such as a vinyl resin, polyurethane, or amino group-containing resin, or a tackifier.

  Examples of the polyester resin include Toyobo Co., Ltd., Byron (registered trademark) 103, 240, 500, GK110, GK640, etc .; Nippon Synthetic Chemical Industry Co., Ltd., Nichigo Polyester (registered trademark) TP- 220, TP-235, TP-236, TP-290, and the like are included, but the present invention is not limited to such examples.

  Examples of the modified olefin resin include Nippon Paper Chemicals Co., Ltd., Aurolen (registered trademark) 100, 200, 350, S-5189, etc .; Sanyo Chemical Industries, Ltd., Umex 1001, 1010, 2000, and the like. Although mentioned, this invention is not limited only to this illustration.

  Examples of the EVA include Tosoh Corporation, Mersen (registered trademark) H-6051, H-6410, and the like; Sumitomo Chemical Co., Ltd., Sumitate (registered trademark) KA-31, KA-42, and the like. However, the present invention is not limited to such examples.

  Examples of the polyvinyl butyral (PVB) include Kuraray Co., Ltd., Mowital (registered trademark) series B30H, B45M, and B60H. However, the present invention is not limited to such examples.

  Examples of the silicone resin include Shin-Etsu Chemical Co., Ltd., product numbers: KE-103 and KE-1013, but the present invention is not limited to such examples.

  Examples of the vinyl chloride resin include Sekisui Chemical Co., Ltd., trade name: Sekisui PVCTS, but the present invention is not limited to such examples.

  Examples of the polyurethane include a product name: Desmopan DP6580A manufactured by DIC Bayer Polymer Co., Ltd., but the present invention is not limited to such examples.

  Examples of the amino group-containing resin include those manufactured by Nippon Shokubai Co., Ltd., trade names: Poliment NK-350, NK-380, etc., but the present invention is not limited to such examples.

  Examples of the tackifier include rosin tackifiers; rosin ester tackifiers, terpene tackifiers, terpene phenol tackifiers, saturated hydrocarbon resins, coumarone tackifiers, Coumarone indene tackifier, styrene resin tackifier, xylene resin tackifier, phenol resin tackifier, petroleum resin tackifier, etc. Each agent may be used alone or in combination of two or more.

  Examples of the rosin-based tackifier include those manufactured by Harima Kasei Co., Ltd. and trade name: Harrier Star DS-90, but the present invention is not limited to such examples.

  Examples of the rosin ester tackifier include Arakawa Chemical Industries, Ltd., trade names: Pine Crystal KE-100, KE-311, and the like, but the present invention is limited to such examples. It is not a thing.

  Examples of the terpene tackifier include Yasuhara Chemical Co., Ltd., Clearon (registered trademark) M-115, P-115, and the like, but the present invention is not limited to such examples.

  Examples of the terpene phenol tackifier include Arakawa Chemical Industries, Ltd., trade name: Tanomaru 803L, and the like, but the present invention is not limited to such examples.

  Examples of the saturated hydrocarbon resin include Arakawa Chemical Industries, Ltd., trade names: Alcon P-90 and P-100, but the present invention is not limited to such examples.

  Examples of the styrene resin-based tackifier include Mitsui Chemicals, Inc., product number: FTR-6000, but the present invention is not limited to such examples.

  The amount of the tackifier may be appropriately adjusted according to the desired tackiness, and is not particularly limited. However, from the viewpoint of improving the tackiness to the adherend per 100 parts by mass of the acrylic polymer, preferably 3 masses. Part or more, more preferably 5 parts by weight or more, and preferably 200 parts by weight or less, more preferably 150 parts by weight or less, from the viewpoint of suppressing a decrease in adhesive strength.

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

  Examples of suitable base materials include polyester base materials, polycarbonate base materials, fluororesin base materials, acrylic base materials, and the like. Among these, a polyester base material and a fluororesin base material are preferable from the viewpoint of weather resistance and cost. Although the thickness of a base material is not specifically limited, Usually, it is preferable that it is about 10-800 micrometers.

  Examples of the polyester used for the polyester substrate include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polycyclohexanedimethanol terephthalate. However, the present invention is not limited to such examples. These polyesters may be used alone or in combination of two or more.

  Examples of the fluororesin used for the fluororesin-based substrate include polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene, polyethylene tetrafluoroethylene, polytetrafluoroethylene, and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. And tetrafluoroethylene-hexafluoropropylene copolymer, and the like, but the present invention is not limited to such examples. These fluororesins 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.

  In addition, as a filler used for a solar cell, EVA, polyvinyl butyral, a silicone resin, a vinyl chloride resin, a polyurethane etc. are mentioned, for example, This invention is not limited only to this illustration. Among these, EVA is preferable from the viewpoint of weather resistance and flame retardancy.

  In the solar cell module backsheet of the present invention, the thickness after drying of the adhesive layer made of an acrylic adhesive containing an acrylic polymer formed on the surface to be bonded to the filler constituting the solar cell module is From the viewpoint of adhesiveness and weather resistance, it is preferably 0.1 μm or more, more preferably 0.3 μm or more, further preferably 1 μm or more, and from the viewpoint of preventing embrittlement, preferably 50 μm or less, more preferably 30 μm or less. More preferably, it is 10 μm or less.

  FIG. 1 is a schematic cross-sectional view showing a configuration when the base material is bonded with an 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 2. The base materials 1 and 1 may be base materials made of the same material, or may be base materials made of different materials.

  Examples of the adhesive 2 include acrylic adhesives, polyester adhesives, polyurethane adhesives, polycarbonate adhesives, and the like, but the present invention is not limited to such examples. The acrylic adhesive is preferably an acrylic adhesive used for the adhesive layer of the solar cell module backsheet of the present invention from the viewpoints of adhesiveness and weather resistance. An adhesive layer 4 containing an acrylic adhesive is formed on one surface of the two substrates 1 and 1.

  In the solar cell module backsheet of the present invention, since the adhesive layer 4 containing an acrylic adhesive is formed, when evaluating the solar cell module as well as the environment actually used as a solar cell. Even when an accelerated test is performed in a high-temperature and high-humidity atmosphere, the adhesion and weather resistance to the filler used in solar cells are excellent, the electrical output characteristics are maintained, and the appearance of the back sheet is poor. An excellent effect that it is difficult to occur is produced.

  FIG. 2 is a schematic cross-sectional view with a barrier layer 3 interposed as another embodiment of the solar cell module backsheet of the present invention. In FIG. 2, adhesives 2 and 2 are applied to one surface of each of the two substrates 1 and 1, and between the layers of the adhesives 2 and 2 formed on the two substrates 1 and 1. An adhesive comprising an acrylic adhesive containing an acrylic polymer on the surface to be bonded to the filler constituting the solar cell module by interposing a barrier layer 3 such as a gas barrier layer on By forming the layer, the back sheet for the solar cell module is formed. Also in the solar cell module backsheet of this embodiment, since the adhesive layer 4 containing an acrylic adhesive is formed, not only the environment actually used as a solar cell but also the solar cell module is evaluated. Even when an accelerated test is performed in a hot and humid atmosphere that is considered in the process, it has excellent adhesion and weather resistance to fillers used in solar cells, maintains electrical output characteristics, and poor appearance of the backsheet An excellent effect is exhibited that it is difficult to produce.

  Among the back sheet for a solar cell module shown in FIG. 1 and the back sheet for a solar cell module shown in FIG. 2, the back sheet for a 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. Examples of the metal vapor deposition film include an aluminum vapor deposition film obtained by vapor-depositing aluminum on a polyester film or a polyolefin-based stretched film.

  Examples of the oxide-deposited film include a film obtained by vapor-depositing aluminum oxide, silicon dioxide, tin oxide, magnesium oxide, indium oxide, and composite oxides thereof on a polyester film, which is transparent and has a gas barrier such as oxygen and water vapor. The thing which has property etc. are mentioned. In these, the film which vapor-deposited silicon dioxide on the polyester film 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 is generally preferably 5 nm or more, more preferably from the viewpoint of forming a uniform oxide vapor deposition layer. 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 the oxide An overcoat layer composed of 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 an adhesive so that the film thickness after drying becomes 0.1 to 20 μm by a method such as gravure coating, roll coating, bar coating, reverse coating on a substrate, for example. An acrylic adhesive containing an acrylic polymer on the surface to be bonded to the filler constituting the solar cell module after the other substrate is bonded to the substrate by a method such as dry lamination It can manufacture by forming the adhesive bond layer which consists of. 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.

  The solar cell module using the back sheet for the solar cell module of the present invention is not only an environment actually used as a solar cell, but also an accelerated test in a high-temperature and high-humidity atmosphere to be considered when evaluating the solar cell module. Even if it is performed, it is excellent in the adhesiveness and weather resistance with respect to the filler used for a solar cell, maintains an electrical output characteristic, and produces the outstanding effect that it is hard to produce the appearance defect of a backsheet.

  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, Inc., trade name: Tetron U298W [white polyethylene terephthalate (hereinafter referred to as PET) film]
Base material 2: manufactured by Mitsubishi Plastics, Inc., trade name: Tech Barrier (silicon dioxide-deposited PET film)
Substrate 3: manufactured by Toray Industries, Inc., trade name: Lumirror X10S (heat-resistant oligomer PET film)
Filler: Mitsui Chemicals Fabro Co., Ltd., trade name: standard cure, product number: SC50B (EVA sheet with a thickness of 400 μm)

Synthesis example 1
In a 500 milliliter flask equipped with a stirrer, a dripping port, a thermometer, a cooling pipe and a nitrogen gas inlet, 60 g of ethyl acetate was charged and refluxed at about 80 ° C. In this flask, 75 g of cyclohexyl methacrylate, 5 g of n-butyl acrylate, 20 g of caprolactone-modified hydroxy methacrylate [manufactured by Daicel Chemical Industries, Ltd., trade name: Plaxel FM1], 2,2′-azobis (2,4 as a polymerization initiator) -Dimethylvaleronitrile) A mixture composed of 0.5 g and ethyl acetate 40 g was continuously dropped into the flask over 2 hours. After further heating for 3 hours, a solution in which the nonvolatile content of the acrylic polymer was 49.9% by mass was obtained.

  The weight average molecular weight of the obtained acrylic polymer was 120,000. Table 1 shows the composition of the monomer components used in the synthesis of the acrylic polymer and the physical properties of the resulting acrylic polymer.

Synthesis Examples 2-12
In Synthesis Example 1, an acrylic polymer was obtained in the same manner as in Synthesis Example 1 except that the composition of 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 CHMA: cyclohexyl methacrylate ST: styrene TBMA: tert-butyl methacrylate BA: n-butyl acrylate HEMA: 2-hydroxyethyl methacrylate FM1: caprolactone-modified hydroxy methacrylate [trade name: Plaxel FM1 manufactured by Daicel Chemical Industries, Ltd. ]
RUVA93: 2- (2′-hydroxy-5′-methacryloyloxyethylphenyl) -2H-benzotriazole [manufactured by Otsuka Chemical Co., Ltd., trade name: RUVA93]
LA82: Monomer having a UV-stable group [Asahi Denka Kogyo Co., Ltd., trade name: ADK STAB LA-82]
Polymerization initiator: 2,2′-azobis (2,4-dimethylvaleronitrile)

Production 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 further nonvolatile with ethyl acetate. The adhesive 1 was obtained by diluting until a part became 10 mass%.

Production Examples 2-9
In Production Example 1, adhesives 2 to 8 were obtained in the same manner as in Production Example 1 except that the composition of the adhesive was changed as shown in Table 2.

Production Example 10
15 parts by mass of a polyisocyanate curing agent [Asahi Kasei Chemicals Co., Ltd., trade name: DURANATE MF-K60X] is added to 100 parts by mass of the acrylic polymer obtained in Synthesis Example 3, and is further nonvolatile with ethyl acetate. Was diluted to 10 mass% to obtain an adhesive 9.

Production Examples 11-13
In Production Example 10, adhesives 11 to 13 were obtained in the same manner as in Production Example 10 except that the composition of the adhesive was changed as shown in Table 2.

Production Example 14
25 parts by mass of a polyisocyanate curing agent [manufactured by Asahi Kasei Chemicals Co., Ltd., trade name: Duranate MF-K60X] and 100% by mass of the acrylic polymer obtained in Synthesis Example 12 and a rosin-based tackifier [Arakawa Chemical Industries, Ltd. Co., Ltd., trade name: Pine Crystal KE-100] 10 parts by mass was put in a container, and further diluted with ethyl acetate until the nonvolatile content became 10% by mass, whereby an adhesive 14 was obtained.

In addition, the hardening | curing agent and tackifier which are shown in Table 2 mean the following.
Curing agent I: polyisocyanate curing agent [manufactured by Sumika Bayer Urethane Co., Ltd., trade name: Desmodur N3200]
Curing agent II: Polyisocyanate curing agent [Asahi Kasei Chemicals Co., Ltd., trade name: Duranate MF-K60X]
Tackifier: Rosin ester tackifier [Arakawa Chemical Industries, trade name: Pine Crystal KE-100]

Examples 1 to 7 [Preparation of back sheet for solar cell module]
As shown in Table 3, any one of the adhesives 1 to 7 was used, and the adhesive was applied to the substrate 1 so that the coating amount after drying was 1 g / m ^2, and then at 100 ° C. for 1 minute. By drying, an adhesive layer was formed. Then, using this base material as the base material 1, the surface on which the adhesive layer of the base material 1 is not formed is the adhesive X in order from the base material 1 to the base material 3 from the filler (EVA sheet described later) side. A laminated body is manufactured by laminating by a dry laminating method so that the base material 1 / adhesive X / base material 2 / adhesive X / base material 3 are laminated. A solar cell module backsheet was prepared by curing at 50 ° C. for 5 days.

As the adhesive X, a main component of a polyester-based adhesive (manufactured by Dainippon Ink and Chemicals, product number: LX703VL) and a polyisocyanate curing agent (manufactured by Dainippon Ink and Chemicals, product number: KE90). Used, and adjusted so that the coating amount after drying of the adhesive X was 10 g / m ² .

Comparative Example 1
A back sheet for a solar cell module was produced in the same manner as in Example 1 except that the adhesive 8 was used instead of the adhesive 1 in Example 1.

Comparative Example 2
A back sheet for a solar cell module was produced in the same manner as in Example 1 except that the adhesive 1 was not used in Example 1.

  Next, the physical properties of the backsheet obtained in each Example or each Comparative Example were examined by the following method. The results are shown in Table 3.

〔Adhesiveness〕
Two back sheets obtained by cutting each example or each comparative example to a width of 60 mm and a length of 150 mm, an EVA sheet (manufactured by Mitsui Chemicals, Inc., product number: SC50B, thickness: 400 μm), a width of 60 mm One piece cut to a length of 60 mm was prepared.

  Place the EVA sheet so that it is positioned at the center of the back sheet cut above, and stack the back sheet / EVA sheet / back sheet in this order so that the surface of the back sheet with the adhesive layer is in contact with the EVA sheet It was.

Next, the obtained laminate was evacuated under a pressure of 5 N / cm ² at a temperature of 130 ° C. for 5 minutes, stored in an oven heated to 150 ° C. for 30 minutes, and allowed to proceed with a crosslinking reaction to obtain a sample. Was made.

  The sample obtained above was sandwiched between the upper and lower clips of a tensile tester (manufactured by Tester Sangyo Co., Ltd.) in an atmosphere at 23 ° C. and a relative humidity of 65%. Using a peeling method, the peeling strength (initial value) at a crosshead speed of 100 mm / min with a width of 10 mm was measured and evaluated based on the following evaluation criteria.

  Further, the sample was left for 1000 hours in an atmosphere of 85 ° C. and a relative humidity of 85%, and then peel strength was measured under the same conditions as described above, and evaluated based on the following evaluation criteria.

(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)

[Weather resistance, electrical output characteristics and appearance of back sheet]
(1) Weather resistance An EVA sheet [manufactured by Mitsui Chemicals Fabro Co., Ltd., product number: SC50B, thickness: 400 μm] was used as a filler for solar cells, and polycrystalline silicon was used as a solar cell. A cell sandwiched between EVA sheets of the same size is placed on A4 size tempered glass, and the back sheet obtained in each Example or Comparative Example 1 is further provided thereon so that the adhesive layer is in contact with the EVA sheet. It was. In addition, since the adhesive layer was not formed in the back sheet obtained in Comparative Example 2, the base material 1 was provided so as to be in direct contact with the EVA sheet.

Thereafter, each laminate obtained above was evacuated for 5 minutes at a temperature of 130 ° C. under a pressure of 5 N / cm ² , and then stored in an oven heated to 150 ° C. for 30 minutes to advance the crosslinking reaction. I let you. After that, the aluminum frame was used to make a sample.

The sample is irradiated with ultraviolet rays for 100 hours or 150 hours at 100 mW / cm ² at a temperature of 60 ° C. and a relative humidity of 50% using an i-super UV tester (manufactured by Iwasaki Electric Co., Ltd., product number: SUV-W151). Thus, a weather resistance acceleration test was conducted.

Next, the peel strength at a crosshead speed of 100 mm / min was measured by a 180 degree peel method using an autograph (manufactured by Shimadzu Corporation), and the formula:
[Retention rate (%)] = [(Peel strength after accelerated test) / (Peel strength before accelerated test)] × 100
Based on the above, the retention rate was determined, and the weather resistance was evaluated based on the following evaluation criteria.

(Evaluation criteria)
Pass: Retention rate is 50% or more Fail: Retention rate is less than 50%

(2) Electrical output characteristics The maximum output of the sample before and after the weather resistance promotion test was measured according to JIS C8913, and the formula:
[Change rate of maximum output (%)]
= [(Maximum output after accelerated test) / (Maximum output before accelerated test)] x 100
The change rate of the maximum output was obtained based on the above, and the electrical output characteristics were evaluated based on the following evaluation criteria.

(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%

(3) Appearance of the back sheet The sample was observed visually for the appearance of the back sheet of the sample after the weather resistance promotion test.

  From the results shown in Table 3, not only the back sheet obtained in each example, but also the environment actually used as a solar cell, in contrast to the back sheet obtained in each comparative example, Even when an accelerated test is performed in a high-temperature and high-humidity atmosphere that is considered when evaluating solar cell modules, it has excellent adhesion and weather resistance to fillers used in solar cells and maintains electrical output characteristics. It can be seen that the appearance of the back sheet is difficult to cause.

Examples 8-13
The base materials 1 to 3 are laminated by the dry laminating method so that the base material 1 / adhesive X / base material 2 / adhesive X / base material 3 are formed in this order from the filler (EVA sheet described later) side. Thus, a laminate was manufactured. In addition, as the adhesive X, a main component of a polyester-based adhesive [Dainippon Ink Chemical Co., Ltd., product number: LX703VL] and a polyisocyanate curing agent [Dainippon Ink Chemical Co., Ltd., product number: KE90] are used. The coating amount after drying of the adhesive X was adjusted to 10 g / m ² .

Next, after the laminate obtained above was cured at 50 ° C. for 5 days, the adhesive shown in Table 4 was used, and the sun was applied so that the coating amount after drying the adhesive was 1 g / m ^2. The solar cell module back sheet was produced by apply | coating on the base material 1 of a battery module back sheet, and making it dry at 100 degreeC for 1 minute, and forming an adhesive bond layer.

Comparative Example 3
A back sheet for a solar cell module was produced in the same manner as in Example 13 except that the adhesive 9 was not used in Example 13.

[Preparation of samples for physical property evaluation]
(1) Sample A
Using one of the back sheets for solar cell modules obtained in Examples 8 to 13 and Comparative Example 3, one sheet obtained by cutting the back sheet for solar cell modules into a width of 60 mm and a length of 200 mm, an EVA sheet [ Mitsui Chemicals Fabro Co., Ltd., product number: RC02B, thickness: 0.4 mm] was cut into a width of 60 mm and a length of 90 mm, and one tempered glass plate having a width of 100 mm and a length of 100 mm was prepared.

  The solar cell module backsheet / EVA sheet / tempered glass plate were laminated in this order so that the surface of the backsheet for solar cell module evaluation was in contact with the EVA sheet.

Next, the laminate obtained above was subjected to a crosslinking reaction under vacuum at a temperature of 150 ° C. under a pressure of 5 N / cm ² for 11 minutes to prepare Sample A.

(2) Sample B
A multi-layer sandwiched between A4 size reinforced glass plates and the same A4 size EVA sheet [manufactured by Mitsui Chemicals Fabro Co., Ltd., product number: RC02B, thickness: 0.4 mm] as a solar cell module filler. After the solar cell made of crystalline silicon is placed, the solar cell module backsheet is further placed thereon so that the adhesive layer of the solar cell module backsheet obtained above is in contact with the EVA sheet. Thus, a laminate was obtained.

The laminate obtained above was subjected to a crosslinking reaction for 11 minutes under a vacuum at a temperature of 150 ° C. under a pressure of 5 N / cm ² , and then framed with an aluminum frame to prepare Sample B. .

  Next, the physical properties of the solar cell module backsheets obtained in Examples 8 to 13 and Comparative Example 3 were examined by the following methods. The results are shown in Table 4.

[Blocking properties]
The solar cell module backsheet obtained above is cut into a width of 5 cm and a length of 20 cm, the surface on which the adhesive layer of the cut sheet is formed, and an untreated PET film (thickness: 188 μm) The laminate obtained was placed in an oven at a temperature of 40 ° C., held for 24 hours while applying a load of 5 kg, then removed from the open, the adhesive layer was observed, and evaluated based on the following evaluation criteria. .

(Evaluation criteria)
◯: The adhesive layer is not transferred to the untreated PET film.
X: The adhesive layer is transferred to an untreated PET film.

〔Adhesiveness〕
Sample A was autographed (manufactured by Shimadzu Corporation) in an atmosphere of 23 ° C., and a tempered glass plate and a solar cell module back sheet were attached to the upper and lower clips, respectively. The peel strength (initial value) at a crosshead speed of 300 mm / min with a width of 25 mm was measured and evaluated based on the following evaluation criteria.

  Further, after leaving Sample A different from that used above in an atmosphere of 85 ° C. and 85% relative humidity for 1000 hours or 2000 hours, the peel strength was measured under the same conditions as above, and the following evaluation criteria were satisfied. Based on the evaluation.

(Evaluation criteria)
A: 40 N / 10 mm or more (excellent adhesiveness)
A: 20 N / 10 mm or more and less than 40 N / 10 mm (adhesiveness is good)
Δ: 5 N / 10 mm or more and less than 20 N / 10 mm (adhesiveness is slightly good)
X: Less than 5 N / 10 mm (adhesiveness is poor)

[Weather resistance, electrical output characteristics and appearance of back sheet]
(1) Weather resistance Sample B was irradiated with ultraviolet rays for 100 hours under the conditions of 100 mW / cm ² at a temperature of 60 ° C. and a relative humidity of 50% using an eye super UV tester (manufactured by Iwasaki Electric Co., Ltd., product number: SUV-W151). Alternatively, a weather resistance promotion test was performed by irradiation for 150 hours.

Next, the peel strength at a crosshead speed of 300 mm / min was measured by a 180 degree peel method using an autograph (manufactured by Shimadzu Corporation), and the formula:
[Retention rate (%)] = [(Peel strength after accelerated test) / (Peel strength before accelerated test)] × 100
Based on the above, the retention rate was determined, and the weather resistance was evaluated based on the following evaluation criteria.

(Evaluation criteria)
Pass: Retention rate is 50% or more Fail: Retention rate is less than 50%

(2) Electrical output characteristics The maximum output of sample B before and after the weather resistance promotion test was measured according to JIS C8913, and the formula:
[Change rate of maximum output (%)]
= [(Maximum output after accelerated test) / (Maximum output before accelerated test)] x 100
The change rate of the maximum output was obtained based on the above, and the electrical output characteristics were evaluated based on the following evaluation criteria.

(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%

(3) Appearance of the back sheet The sample was observed visually for the appearance of the back sheet of the sample after the weather resistance promotion test.

  From the results shown in Table 4, the solar cell module backsheets obtained in each example are actually solar cells in comparison with the solar cell module backsheets obtained in the respective comparative examples. Not only in the environment where it is used, but also when it is subjected to an accelerated test in a high-temperature and high-humidity atmosphere, which is considered when evaluating solar cell modules, the adhesion and weather resistance to fillers used in solar cells It can be seen that the electrical output characteristics are excellent and the appearance of the back sheet is difficult to cause. Moreover, since the block polyisocyanate compound was used for the solar cell module backsheet obtained in Examples 8-12 as a hardening | curing agent, the polyisocyanate compound obtained in Example 13 was used as a hardening | curing agent. Compared with the back sheet for a solar cell module, not only was the environment actually used as a solar cell, but also a case where an accelerated test was performed in a high-temperature and high-humidity atmosphere to be considered when evaluating the solar cell module. However, it turns out that it is further excellent in the adhesiveness with respect to the filler used for a solar cell.

  From the above, it can be seen that any of the solar cell module backsheets obtained in each example can be suitably used for solar cell modules and solar cells.

  The back sheet for the solar cell module of the configuration of the present invention is not only in an environment actually used as a solar cell, but also in a case where an accelerated test is performed in a high-temperature and high-humidity atmosphere studied when evaluating the solar cell module. Even so, it has excellent adhesion and weather resistance to fillers used in solar cells, maintains electrical output characteristics, and does not easily cause poor appearance of the backsheet, so it should be used suitably for solar cell modules and solar cells. Can do.

1: Base material 2: Adhesive 3: Barrier layer 4: Adhesive layer

Claims (5)

A backsheet used for a solar cell module, on a surface to be bonded to a filler constituting the solar cell module, the general formula (I):
^{_{CH 2 = C (R 1)}} -CO-OZ (I)
(Wherein 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, wherein an adhesive layer made of an acrylic adhesive containing an acrylic polymer obtained by polymerizing a monomer component containing a monomer represented by formula (1) is formed.   The back sheet for a solar cell module according to claim 1, wherein the acrylic adhesive further contains a curing agent.   The back sheet for a solar cell module according to claim 2, wherein the curing agent is at least one selected from the group consisting of a (block) polyisocyanate compound, an epoxy resin, and an oxazoline group-containing resin.   It has a solar cell module backsheet in any one of Claims 1-3, The solar cell module characterized by the above-mentioned.   A solar cell comprising the solar cell module according to claim 4.