JP2015076505A - Backside protective sheet for solar battery modules, method for manufacturing the same, and method for manufacturing solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a backside protective sheet for solar battery modules which is small in the drop in adhesion strength between film layers even after being used under a high-temperature and high-humidity environment for a long period of time, and small in curl after being cut; a method for manufacturing such a backside protective sheet; and a method for manufacturing a module for solar batteries arranged by use thereof.SOLUTION: A backside protective sheet for solar battery modules comprises: a plastic film 16; a thermally adhesive resin film 11; and an adhesive agent 15 by which the plastic film and the thermally adhesive resin film are glued to each other. In the backside protective sheet, the adhesion strength between the film layers is 2 N/15 mm or more, and the curl is 10 mm or less. The adhesive agent 15 includes (a) polyester polyol, and to 100 pts.wt. of the polyester polyol, (b)5-30 pts.wt. of an epoxy resin, (c)5-30 pts.wt. of polycarbonate polyol, (d)1-10 pts.wt. of a carbodiimide compound, (e)10-30 pts.wt. of a polyisocyanate compound, and (f)0.002-1 pts.wt. of a curing-accelerating catalyst.

Description

  The present invention relates to a back surface protection sheet for a solar cell module and a method for producing the same, and more specifically, in a back surface protection sheet in which a plastic film and a heat adhesive resin film are bonded together, an adhesive having excellent weather resistance is used. Even when used in a high temperature and high humidity environment, it is possible to suppress a decrease in adhesion strength between films, and by adding a curing accelerating catalyst to the adhesive, aging curing at low temperature is possible, and the film during aging curing The present invention relates to a back surface protection sheet for a solar cell module capable of suppressing curling due to heat shrinkage and a method for producing the same.

  In recent years, solar power generation as a clean energy source has attracted attention due to increasing awareness of environmental problems, and solar cell modules having various forms have been developed and proposed. Generally, a solar cell module uses a crystalline silicon solar cell element or an amorphous silicon solar cell element, and is filled with a surface protection sheet, an ethylene / vinyl acetate copolymer resin (hereinafter sometimes abbreviated as EVA), and the like. It is manufactured by a method in which a material sheet, a solar cell element, a filler sheet, and a back surface protective sheet are laminated in this order, and are integrated by thermocompression bonding with vacuum suction. As the back protective sheet, a plastic base material that is lightweight and excellent in electrical characteristics and strength has been generally used.

  The solar cell module is required to maintain its performance for a long period of 20 years or longer. The back protection sheet is excellent in strength, weather resistance, heat resistance, water resistance, light resistance, chemical resistance, light reflectivity, light diffusibility, moisture resistance, antifouling property, design, etc., and these change over time It is necessary to prevent this, and a back surface protection sheet in which a polyester film such as polyethylene terephthalate having excellent weather resistance and electrical insulation and another film material are bonded together with an adhesive is widely used.

  The back surface protection sheet for a solar cell module is produced by pasting a plurality of long film substrates with an adhesive and then aging curing to obtain a film laminate, which is cut to a required width. However, the film may shrink due to the heat load at the time of aging curing, and the back protective sheet after cutting may be curled. In the process of manufacturing a solar cell module, when the members constituting the solar cell module are handled by a machine, it cannot be handled well if the back surface protection sheet is curled, so the back surface protection sheet after cutting may be flat. It is desired.

  As a countermeasure against the above curl, when film bases with different heat shrinkability are bonded together with an adhesive, the film base with high heat shrinkability is wound on the outside of the roll, and the back surface reduces curling by aging curing. A method for manufacturing a protective sheet has been proposed (see, for example, Patent Document 1). According to this production method, when a film material having a glass transition temperature lower than room temperature, such as a polyethylene film, a polypropylene film, or an EVA film, is used as a film substrate, the shrinkage due to the heat load during aging curing is still large. The back surface protection sheet after cutting has a large curl, and there is a problem that the back surface protection sheet is poorly handled when the solar cell module is manufactured.

  Here, for the adhesive for bonding, in order to maintain the adhesion strength between the film layers in a long-term high temperature and high humidity environment required for the back surface protection sheet, in addition to the selection of the adhesive, Curing by aging at a high temperature and for a long time was indispensable, and the occurrence of curling was inevitable.

JP 2012-151170 A

  The subject of this invention is providing the back surface protection sheet for solar cell modules with the fall of the adhesion strength between film layers being small also in the use in a long-term high-temperature, high-humidity environment, and the curl after cutting is small. .

  1st invention is the back surface protection sheet for solar cell modules by which a plastic film and a thermoadhesive resin film are bonded together by an adhesive agent, Comprising: Adhesion strength between film layers is 2 N / 15mm or more, and curl is 10 mm or less It is the back surface protection sheet for solar cell modules characterized by being.

  In the second invention, the adhesive is 5 to 30 parts by weight of the epoxy resin (b), 5 to 30 parts by weight of the polycarbonate polyol (c), carbodiimide compound (d) 1 with respect to 100 parts by weight of the polyester polyol (a). 10 to 30 parts by weight, 10 to 30 parts by weight of a polyisocyanate compound (e), and 0.002 to 1 part by weight of a curing accelerating catalyst (f).

  The third invention is characterized in that the curing accelerating catalyst (f) is zinc stearate.

  The fourth invention is characterized in that the curing rate of the adhesive is 70% or more.

  The fifth invention is characterized in that the adhesion strength between the film layers is maintained at 2 N / 15 mm after storage for 1000 hours under the condition of 85 ° C. × 85% RH.

  6th invention, a plastic film and a heat-adhesive resin film are 5-30 weight part of epoxy resin (b), 5-30 weight part of polycarbonate polyol (c) with respect to 100 weight part of polyester polyol (a), After bonding, 1 to 10 parts by weight of the carbodiimide compound (d), 10 to 30 parts by weight of the polyisocyanate compound (e), and 0.002 to 1 part by weight of the curing accelerating catalyst (f) It is a manufacturing method of the back surface protection sheet for solar cell modules aging for 48 hours or more at the temperature of 20 degreeC or more and less than 40 degreeC.

  7th invention is a manufacturing method of the solar cell module using the back surface protection sheet for solar cell modules of one of the said inventions, Comprising: As the direction in which this thermoadhesive resin film surface faces an EVA sheet layer, a solar cell module A photovoltaic power generation element / EVA sheet layer / glass plate as a photovoltaic element provided with a back surface protection sheet / EVA sheet layer / wiring is laminated in this order, and these layers are thermocompression-molded as an integral molded body. This is a method for manufacturing a solar cell module to which a frame is attached.

  According to the present invention, it has sufficient adhesion strength at the time of processing, has good handling properties due to small curl after cutting, can improve the yield when producing solar cell modules, even in a high temperature and high humidity environment, The back surface protection sheet for solar cell modules with a small fall of the adhesive strength between film layers is obtained.

It is the schematic sectional drawing which showed an example of the back surface protection sheet for solar cell modules of this invention. It is the schematic sectional drawing which showed an example of the solar cell module using the back surface protection sheet for solar cell modules of this invention.

  Hereinafter, the back surface protection sheet for solar cell modules according to the present invention and the solar cell module using the same will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an example of the layer structure of the back surface protective sheet for a solar cell module of the present invention.

  The back surface protection sheet for solar cell modules in this invention is a back surface protection sheet for solar cell modules (10) in which a plastic film (16) and a heat-adhesive resin film (11) are laminated by an adhesive layer (15). It is.

  Examples of the plastic film include polyester films such as polyethylene terephthalate (hereinafter sometimes abbreviated as PET) and polyethylene naphthalate (hereinafter sometimes abbreviated as PEN), polyolefin films such as polyethylene and polypropylene, and polystyrene films. Examples thereof include polyamide film, polyvinyl chloride film, polycarbonate film, polyacrylonitrile film, polyimide film, and fluorine resin film. Among these, from the viewpoint of mechanical strength, heat resistance, and economy, a PET film is more preferably used, and is a hydrolysis-resistant polyester film, particularly a hydrolysis-resistant PET film because long-term property maintenance is required. Even more preferred. Similarly, it is more preferable that it is a PEN film because high hydrolysis resistance is obtained.

  The hydrolysis resistant polyester film is a polyester film in which the breaking elongation after treating at 120 ° C. and 100% RH for 60 hours retains 50% or more of the initial breaking elongation. A hydrolysis-resistant polyester film having a breaking elongation of 50% or more of the initial breaking elongation after treatment at 120 ° C. and 100% RH for 60 hours is used as a plastic film constituting the back protective sheet for solar cell modules By doing so, the weather resistance of the back surface protection sheet for solar cell modules can be greatly improved, which can contribute to performance guarantee for 10 years or more as a solar cell module, which is preferable.

  The thermal adhesive resin film in the present invention refers to a film having thermal adhesiveness with a sealing material sheet such as an EVA sheet which is a constituent material of the solar cell module. Polyolefin is preferably used as the resin for the heat-adhesive resin film. Polyolefin is a single or copolymerized olefin monomer such as ethylene, propylene, 1-butene, 1-pentene, and is preferably a polyethylene resin and a polypropylene resin in terms of heat resistance, and polypropylene is more preferable than polyethylene. The main resin (polypropylene resin) is more excellent in heat resistance, is less susceptible to deformation under high temperature and high pressure when molding a solar cell module, and is more preferably used when the processing temperature is high.

  The melting point of the polypropylene resin is preferably in the range of 140 ° C. to 170 ° C. from the viewpoints of heat resistance, slipperiness, film handling properties, curl resistance, and thermal adhesiveness with the adhesive resin layer. When the melting point is 140 ° C. or higher, the heat resistance is excellent, and when the back protection sheet member film for a solar cell module is heat-sealed with a sealing material sheet, the thickness is reduced or the insulation resistance is reduced. It is preferable because defects can be suppressed. By setting the melting point to 170 ° C. or lower, it is possible to ensure excellent adhesion strength with the sealing material sheet.

  As the heat adhesive resin film in the present invention, an EVA resin film having a vinyl acetate content of 2 to 20% by weight can also be used. When the vinyl acetate content is 2% by weight or more, the adhesiveness with the sealing material sheet can be made good, and when it is 20% by weight or less, the handling property can be made good without blocking.

  In the plastic film or the heat-adhesive resin film in the present invention, an appropriate whitening agent or blackening agent can be added as needed in an amount that does not impair the effects of the present invention. Calcium carbonate, silica, alumina, magnesium hydroxide, zinc oxide, talc, kaolin clay, titanium oxide, barium sulfate, carbon black, carbon nanotubes, aniline black, black iron oxide, etc. can be added as a blackening agent. Of these, titanium oxide is preferable for the whitening agent, and carbon black is preferable for the blackening agent.

  In the present invention, the adhesive used for laminating the plastic film and the heat-adhesive resin film is 5 to 30 parts by weight of the epoxy resin (b) and 100 parts by weight of the polycarbonate polyol (100 parts by weight of the polyester polyol (a). c) containing 5 to 30 parts by weight, 1 to 10 parts by weight of carbodiimide compound (d), 10 to 30 parts by weight of polyisocyanate compound (e) as a curing agent, and curing even at low temperature aging It is preferable that 0.002 to 1 part by weight of a curing accelerating catalyst (f) for enhancing the properties is blended. By using such an adhesive, it is possible to provide a back surface protection sheet for a solar cell module that has sufficient adhesion strength and curl characteristics for processing and has a small decrease in adhesion strength over time.

  The polyester polyol (a), which is the main component of the adhesive, is obtained by condensation polymerization of dicarboxylic acid and polyhydric alcohol, and polyester diol obtained by condensation polymerization of dicarboxylic acid and diol is representative. Dicarboxylic acids include malonic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid and other aliphatic dicarboxylic acids, fumaric acid, maleic anhydride and other unsaturated dicarboxylic acids, phthalic acid, dimethyl Aromatic dicarboxylic acids such as phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid and dimethyl terephthalic acid.

  Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, neopentyl glycol, 1,5 -Pentanediol, 1,6-hexanediol, 3-methyl 1,5-pentanediol, 2-ethyl 1,3-hexanediol, 2,2,4-trimethyl 1,3-pentanediol, 1,8-octane Diols, aliphatic glycols such as 1,10-decanediol, cyclohexanediol, cyclohexanedimethanol, alicyclic glycols such as hydrogenated bisphenol A, xylene glycol, bishydroxyethoxybenzene, bishydroxyethyl terephthalate, etc. Family glycol, trimethylol propane, and aliphatic triols such as glycerin can be exemplified. Various known polyester polyols based on these combinations can be used, but those having a number average molecular weight in the range of 1000 to 40000 are preferred, and those having a hydroxyl value of 1 to 30 mgKOH / g can be used. If the number average molecular weight is less than 1000, the adhesive strength is insufficient, and if it exceeds 40000, the workability, the coating film appearance, and the solubility may be inferior.

  As the epoxy resin (b) used for the adhesive in the present invention, a bisphenol type epoxy resin which is a copolymer of bisphenol A or bisphenol F and epichlorohydrin can be used, and the number average molecular weight is 500 to 1500. Is preferred. When the number average molecular weight is 500 or more, the heat-and-moisture resistance as an adhesive can be improved, and when the number-average molecular weight is 1500 or less, the solubility in the coating agent can be improved. As the epoxy resin (b), for example, a bisphenol A type epoxy resin having a number average molecular weight of about 1000 is used.

  The addition amount of the epoxy resin (b) used in the adhesive in the present invention is not sufficient moisture and heat resistance if the blending amount is small, and if the blending amount is large, poor coating due to wetting and repelling of the adhesive occurs. It is preferable to blend 5 to 30 parts by weight with respect to 100 parts by weight of the polyester polyol (a).

  The polycarbonate polyol (c) used for the adhesive in the present invention is generally a polycarbonate diol composed of a diol and a carbonate, and has a number average molecular weight of 500 to 3000 and a hydroxyl value of 20 to 200 mgKOH / g in order to maintain weather resistance and adhesive strength. Is selected. Examples of the diol for producing the polycarbonate diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1 Diols having no side chain, such as 1,8-octanediol, 1,9-nanodiol, 1,10-dodecanediol, 1,11-undecanediol, 1,12-dodecanediol, 2-methyl-1,8-octane Diol, 2-ethyl-1,6-hexanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 2, 4-diethyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,2- Diols having a side chain, such as methyl-1,3-propanediol, 1,4-cyclohexanedimethanol, 2-bis (4-hydroxycyclohexyl) - are selected from cyclic diols such as propane.

  Further, as carbonates, dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, and dibutyl carbonate, diaryl carbonates such as diphenyl carbonate, ethylene carbonate, trimethylene carbonate, 1,2-propylene carbonate, 1,2-butylene carbonate, It is selected from alkylene carbonates such as 1,3-butylene carbonate and 1,2-pentylene carbonate.

  Of these, polycarbonate diols composed of aliphatic diols (1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, etc.) and ethylene carbonate are preferably used. .

  The addition amount of the polycarbonate polyol resin (c) used for the adhesive in the present invention is not sufficient moisture and heat resistance when the blending amount is small, and when the blending amount is large, the heat and moisture resistance is obtained, but the adhesion strength is reduced. It is preferable to mix 5 to 30 parts by weight with respect to 100 parts by weight of the polyester polyol (a).

  A carbodiimide compound (d) is added to the adhesive in the present invention in order to seal a carboxyl group remaining in the adhesive composition or generated by hydrolysis and promoting hydrolysis.

  Examples of the carbodiimide compound include dicyclohexylcarbodiimide, diisopropylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, octyldecylcarbodiimide, di-t-butylcarbodiimide, dibenzylcarbodiimide, diphenylcarbodiimide, N-octadecyl-N′-phenylcarbodiimide, and N-benzylcarbodiimide. -N'-phenylcarbodiimide, N-benzyl-N'-tolylcarbodiimide, di-o-toluylcarbodiimide, di-p-toluylcarbodiimide, bis (p-aminophenyl) carbodiimide, bis (p-chlorophenyl) carbodiimide, bis ( o-chlorophenyl) carbodiimide, bis (o-ethylphenyl) carbodiimide, bis (p-ethylphenyl) carbodi Midobis (o-isopropylphenyl) carbodiimide, bis (p-isopropylphenyl) carbodiimide, bis (o-isobutylphenyl) carbodiimide, bis (p-isobutylphenyl) carbodiimide, bis (2,5-dichlorophenyl) carbodiimide, bis (2, 6-dimethylphenyl) carbodiimide, bis (2,6-diethylphenyl) carbodiimide, bis (2-ethyl-6-isopropylphenyl) carbodiimide, bis (2-butyl-6-isopropylphenyl) carbodiimide, bis (2,6- Diisopropylphenyl) carbodiimide, bis (2,6-di-t-butylphenyl) carbodiimide, bis (2,4,6-trimethylphenyl) carbodiimide, bis (2,4,6-triisopropylphenyl) carboxy Bodiimide, bis (2,4,6-tributylphenyl) carbodiimide, di-β-naphthylcarbosiimide, N-tolyl-N′-cyclohexylcarbosiimide, N-tolyl-N′-phenylcarbosiimide, p- Phenylenebis (o-toluylcarbodiimide), p-phenylenebis (cyclohexylcarbodiimide), p-phenylenenebis (p-chlorophenylcarbodiimide), 2,6,2 ', 6'-tetraisopropyldiphenylcarbodiimide, hexamethylenebis (cyclohexylcarbodiimide) ), Ethylene bis (phenylcarbodiimide), ethylene bis (cyclohexylcarbodiimide), and other mono- or polycarbodiimide compounds.

  Of these, bis (2,6-diisopropylphenyl) carbodiimide and 2,6,2 ', 6'-tetraisopropyldiphenylcarbodiimide are preferred from the viewpoints of reactivity and stability. Furthermore, a commercially available polycarbodiimide compound as the polycarbodiimide compound can be suitably used without the need for synthesis. As such a commercially available polycarbodiimide compound, for example, various grades sold under the trade name “Carbodilite” (registered trademark) marketed by Nisshinbo Chemical Co., Ltd. can be used.

  The carbodiimide compound (d) has a carbodiimide equivalent (molecular weight / number of carbodiimide groups contained in the molecule) of 100 to 1000, and preferably 1 to 10 parts by weight per 100 parts by weight of the polyester polyol (a). If it is less than 1 part by weight, the hydrolysis resistance is insufficient, and if it exceeds 10 parts by weight, the hue becomes yellowish, which may cause problems in appearance.

  The polyisocyanate compound (e) which is a curing agent component of the adhesive in the present invention is one or more selected from aliphatic, alicyclic, araliphatic and aromatic, such as hexamethylene diisocyanate, Aliphatic isocyanates such as pentamethylene diisocyanate, propylene diisocyanate, aliphatic isocyanates such as butylene diisocyanate, cyclohexane diisocyanate, methylene bis (cyclohexyl isocyanate), isophorone diisocyanate, aromatic aliphatic isocyanates such as xylylene diisocyanate, tetramethylxylylene diisocyanate, Examples include aromatic isocyanates such as tolylene diisocyanate and diphenylmethane diisocyanate. In addition, adducts, dimers, trimers, carbodiimide-modified products, allophanate-modified products, burette-modified products, nurate-modified products, and the like of these diisocyanates can also be used.

  Among the above-mentioned isocyanate-based curing agents, hexamethylene diisocyanate, isophorone diisocyanate, and xylylene diisocyanate, which are excellent in weather resistance and coating film performance, are preferable. Easy and preferred.

  In the polyisocyanate compound (e) in the present invention, if the blending amount is small, the adhesive is not sufficiently cured, and if the blending amount is large, the adhesion strength is lowered. Therefore, the polyester polyol (a) constituting the main component is added to 100 parts by weight. On the other hand, it is preferable to mix 10 to 30 parts by weight.

  The solvent used for the adhesive in the present invention is preferably a solvent having no active hydrogen such as esters, ketones, aliphatics, and aromatics. Examples of the esters include ethyl acetate, propyl acetate, and butyl acetate. Examples of ketones include methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of the aliphatic group include n-heptane, n-hexane, cyclohexane and the like. Examples of aromatics include toluene and xylene. Of these, ethyl acetate, propyl acetate, and methyl ethyl ketone are particularly preferable from the viewpoints of solubility and coating suitability.

  The curing accelerating catalyst (f) in the present invention is an adhesive curing reaction, that is, a hydroxyl group (—OH) contained in the polyester polyol (a) and the polycarbonate polyol (c), and an isocyanate group in the polyisocyanate compound (e). It promotes the formation reaction of urethane bonds by the reaction of (—N═C═O), and is used to increase the reaction rate and increase the productivity. As the curing accelerating catalyst, zinc-based organometallic catalysts such as zinc stearate and zinc naphthenate, tin-based organometallic catalysts such as tin octylate, dibutyltin diacetate, dibutyltin dilaurate, and dioctyltin dilaurate are used, and DBU (1 , 8-diazabicyclo [5,4,0] undecan-7-ene), amines such as triethylamine and triethylenediamine, imidazole, and the like can be used.

  Among them, zinc stearate is preferable because it has excellent viscosity stability at room temperature of the adhesive resin composition and can secure a sufficient pot life. The curing accelerating catalyst (f) is preferably 0.002 to 1 part by weight, particularly preferably 0.005 to 0.1 part by weight, based on 100 parts by weight of the polyester polyol (a). When the blending amount exceeds 0.002 parts by weight, the effect of accelerating curing is remarkable, and by making it less than 1 part by weight, gelation due to the reaction between the polyol and the polyisocyanate compound at room temperature is suppressed, and a sufficient pot life is achieved. It is preferable because it can be secured.

  In the present invention, the adhesive strength between the film layers of the plastic film and the thermoplastic resin film is preferably 2 N / 15 mm or more, more preferably 3 N / 15 mm or more, and the curl is 10 mm or less, more preferably 9 mm or less.

  If the adhesion strength between the film layers is less than 2 N / 15 mm, it is inconvenient because the films are peeled off or shifted when processed into a solar cell module. The adhesion strength is preferably 5 N / 15 mm or more.

  The curl needs to be 10 mm or less. If it exceeds 10 mm, the handling property when processing into a solar cell module is poor, and the yield is deteriorated due to problems such as the entire back surface protection sheet being displaced from the specified position.

  The curing rate of the adhesive in the back surface protective sheet for solar cell module of the present invention is preferably 70% or more, and more preferably 80% or more. By making it 70% or more, it becomes easy to obtain an adhesion strength of 2 N / 15 mm or more.

  In addition, it is preferable that the equivalent ratio (isocyanate group / hydroxyl group) of an isocyanate group and a hydroxyl group is 1.0 or more, More preferably, it is 1.2 or more, More preferably, it is 1.5 or more. The adhesive curing rate is calculated based on the degree of consumption of isocyanate groups. If the equivalent ratio of isocyanate groups to hydroxyl groups is less than 1.0, unreacted hydroxyl groups will remain even if the isocyanate groups have reacted completely. In some cases, a decrease in adhesion strength under high temperature and high humidity may be a problem.

The coating amount of the adhesive layer in the back protective sheet and manufacturing method thereof for a solar cell module of the present invention, 3 g / m ² or more, and preferably more than 4-6 g / m ² from the viewpoint of cost and adhesion .

  In order for the solar cell back surface protective sheet of the present invention to prevent film delamination in the use environment, it is 2 N / 15 mm or more, more preferably 2.5 N / 15 mm or more after storage for 1000 hours under the condition of 85 ° C. × 85% RH. It is preferable to maintain the adhesion strength.

  As a manufacturing method of the back surface protection sheet for solar cell modules in the present invention, for example, a known coating method such as a gravure / roll coating method on a plastic film, or a method such as dry lamination in which an adhesive is applied using a printing method or the like A heat-adhesive resin film can be bonded together. At this time, the plastic film can be subjected to a surface treatment for improving adhesiveness such as corona treatment or plasma treatment, if necessary. Next, the adhesive coating surface of the plastic film and the heat-adhesive resin film are bonded together.

  In the production of the back surface protective sheet for a solar cell module of the present invention, it is important to age at a temperature of 20 ° C. or higher and lower than 40 ° C. for 48 hours or longer after the bonding. If it is less than 20 ° C., curing is insufficient even if it takes time, and if it exceeds 40 ° C., the curl becomes large. If the aging time is less than 48 hours, curing is still insufficient.

Below, the method to manufacture a solar cell module using the back surface protection sheet for solar cell modules of this invention is demonstrated. FIG. 2 shows a schematic sectional side view of an example in which a solar cell module is produced. The back surface protective sheet for solar cell module (10) / EVA sheet layer of the present invention in the direction in which the heat-adhesive resin film (11) surface of the back surface protective sheet for solar cell module (10) faces the EVA sheet layer 2 (23) 2 (23) / photovoltaic power generation element (25) / EVA sheet layer 1 (22) / glass plate (24) as a photovoltaic element provided with wirings are laminated in this order. Other materials are arbitrarily laminated to each other, and then these layers are integrated by vacuum suction or the like, and a normal molding method such as a thermocompression method is used. A method of manufacturing a solar cell module by mounting is preferably exemplified.
By using the back surface protection sheet for a solar cell module with a small curl of the present invention, the back surface protection sheet is excellent in handling properties when laminating the back surface protection sheet, and when the solar cell module is formed, the back surface protection sheet is displaced or wrinkles are generated. This is preferable because it can be suppressed.

Hereinafter, the present invention will be described in detail by way of examples. Each characteristic was measured and evaluated by the following methods.
[Evaluation method]
(Back side protection sheet configuration for solar cell module)
Table 1 shows the back surface protective sheet member for the solar cell module and the adhesive constituent components.

(Adhesive curing rate)
A test sample before and after the plastic film and the heat-adhesive resin film are bonded together with an adhesive and subjected to an aging treatment at a predetermined temperature and a predetermined time, and a correction sample that is completely cured (110 ° C. × 2 hours heat treatment). Two types were prepared, and the absorbance peak height of the IR spectrum (2260 cm ⁻¹ ) before and after curing of the isocyanate group was measured by a transmission method using FT-IR (Fourier transform infrared spectrophotometer), and obtained from the following formula. .

Adhesive curing rate (%) = [(absorbance peak height before aging) − (absorbance peak height after aging)] ÷ [(absorbance peak height before aging) − (absorbance peak height after complete curing)] × 100
<Measurement conditions>
Apparatus: FTS-55A (FT-IR manufactured by Bio-Rad DIGILAB)
Light source: Special ceramic detector: MCT
Purge: Nitrogen gas resolution: 2 cm ⁻¹
Integration number: 512 times Measurement method: Transmission method Measurement wavelength range: 2500 to 2000 cm ⁻¹ .

(curl)
The plastic film and the heat-adhesive resin film were bonded together with an adhesive, and after aging treatment at a predetermined temperature and a predetermined time, the laminate was cut to obtain a 20 cm × 20 cm size sheet. This sheet is stored for 24 hours in an environment of 23 ± 5 ° C. and 50 ± 10% RH, and then placed on a flat surface with the heat-adhesive resin film face up, and the warp height from the flat surface to the four apexes is vernier. The average value was taken as the curl value.

(Adhesion strength between film layers)
The back protective sheet for solar cell module is cut into a width of 15 mm, peeled between the film layers, and peel strength is measured at a peel angle of 180 ° and a peel speed of 100 mm / min using ORIENTEC's Tensilon PTM-50. This value was used as the initial adhesion strength between the film layers.

  Next, the back surface protection sheet for solar cell modules is cut into a width of 15 mm and stored for 1000 hours in an environment of temperature 85 ° C. and humidity 85% RH using a constant temperature and humidity chamber PR-2KPH manufactured by ESPEC Co., Ltd. The adhesion strength between the film layers was measured by the method.

(Example 1)
Biaxially stretched polyethylene terephthalate film with hydrolysis resistance ("Lumirror" (registered trademark) X10S, 125 μm, manufactured by Toray Industries, Inc.) with a dry laminator (Dry Laminator OG / DL-130TA-AF with one-color printing manufactured by Okazaki Machinery Co., Ltd.) In addition, 100 parts by weight of “Dick Dry” (registered trademark) LX-71A (manufactured by DIC) having a polyester polyol, a number average molecular weight of 5000, and a hydroxyl value of 11 mgKOH / g as an epoxy resin is used as an epoxy resin. "1050 parts by weight (manufactured by DIC)" and 15 parts by weight of "Placcel" (registered trademark) CD210 (manufactured by Daicel Chemical Industries) having a number average molecular weight of 1000 and a hydroxyl value of 110 mgKOH / g as a polycarbonate polyol, Hardness of isocyanate compounds 17 parts by weight of “Desmodur” (registered trademark) N3300 (manufactured by Sumitomo Bayer Urethane Co., Ltd.), which is a nurate modified hexamethylene diisocyanate as an agent, and “Carbodilite” (registered trademark) V— having a carbodiimide group equivalent of 200 as a carbodiimide compound. 2 parts by weight of 07 (manufactured by Nisshinbo Chemical Co., Ltd.) and 0.05 parts by weight of zinc stearate (“Nissan Electol” (registered trademark) MZ-2, manufactured by Nissho Co., Ltd.) as a curing accelerating catalyst were mixed. The coating was applied to a coating amount of 5 g / m ² , dried, and laminated with a white polypropylene film (manufactured by Toray Film Processing Co., Ltd., type name B011W, 150 μm) and a nip pressure of 60 N / cm.

This white polypropylene film B011W is a film having a three-layer structure of A layer / B layer / C layer. As a resin used for the A layer, 1-butene is copolymerized, and has a melting point of 127 ° C. and a density of 0.94 g / a cm ³ to a melt flow rate 5 g / 10 min linear low density polyethylene 85 parts by weight, melting point 112 ° C., 15 parts by weight of low density polyethylene having a density of 0.91 g / cm ^3, and a propylene resin A resin mixture obtained by mixing 80 parts by weight of an ethylene / propylene random copolymer having a melting point of 150 ° C. and a density of 0.900 g / cm ³ was used. The resin used for layer B is 12 parts by weight of a titanium oxide master batch (homopolypropylene base, concentration 60% by weight) with respect to 100 parts by weight of homopolypropylene having a melting point of 160 ° C. and a density of 0.90 g / cm ^3. A mixed resin mixture was used. The amount of titanium oxide added is 6.4% by weight. As the resin used for the C layer, an ethylene / propylene block copolymer resin having a melting point of 160 ° C. and a density of 0.900 g / cm ³ was used. Using these resin compositions, the ratio of the thickness of the A / B / C layer is 20/70/10 and the total thickness is 150 μm, which is molded by a known coextrusion method. The bonding was performed on the C layer side.
The pasted back protective sheet was aged at a temperature of 25 ° C. for 72 hours to cause the adhesive layer to undergo a curing reaction, thereby producing a back protective sheet for a solar cell module.

(Example 2)
The resin component of the adhesive is polyester polyol, “Eritel” (registered trademark) XO-0276 (manufactured by Unitika) having a number average molecular weight of 20000 and a hydroxyl value of 4 mg KOH / g, and “Epiclon” (registered trademark) 1050 as an epoxy resin. Was changed to 7 parts by weight and “carbodilite” (registered trademark) V-07 was changed to 4 parts by weight as a carbodiimide compound, to prepare a back protective sheet for a solar cell module in the same manner as in Example 1.

(Example 3)
The resin component of the adhesive is polyester polyol, “Beckolite” (registered trademark) M-6180-50 (manufactured by DIC) having a number average molecular weight of 6000 and a hydroxyl value of 21 mg KOH / g, and “Epiclon” (registered) as an epoxy resin. (Trademark) 1050 is 25 parts by weight, “Plexel” (registered trademark) CD210 is 10 parts by weight as polycarbonate polyol, “Desmodur” (registered trademark) N3300 is 25 parts by weight as polyisocyanate compound, and “carbodilite” is as carbodiimide compound. A back protective sheet for a solar cell module was prepared in the same manner as in Example 1 except that 7 parts by weight of “(registered trademark) V-07” was used.

Example 4
The resin component of the adhesive is “Aronmelt” (registered trademark) PES-375SE50 (manufactured by Toagosei Co., Ltd.) having a number average molecular weight of 13,000 and a hydroxyl value of 11 mgKOH / g as polyester polyol, and “Placcel” (registered trademark) as polycarbonate polyol. Except for mixing 25 parts by weight of CD210 with 13 parts by weight of “Desmodur” (registered trademark) N3300 as a polyisocyanate compound and 4 parts by weight of “carbodilite” (registered trademark) V-07 as a carbodiimide compound. A back protective sheet for a solar cell module was produced in the same manner as in Example 1.

(Example 5)
The resin component of the adhesive is a polyisocyanate compound, “Desmodur” (registered trademark) N3200 (manufactured by Sumitomo Bayer Urethane Co., Ltd.), which is a burette modified product of hexamethylene diisocyanate, and aged at a temperature of 25 ° C. for 72 hours. The back surface protection sheet for solar cell modules was produced like Example 1 except having implemented and carrying out hardening reaction of the adhesive bond layer.

(Example 6)
In Example 2, the back surface protection sheet for solar cell modules was produced similarly to Example 2 except having set epoxy resin "Epiclon" 1050 to 3 weight part. Although the adhesion strength after 85 hours at 85 ° C. and 85% RH was slightly lowered due to the small amount of the epoxy resin added, there was no practical problem.

(Example 7)
The resin component of the adhesive is "Beccolite" (registered trademark) M-6180-50 as the polyester polyol, 10 parts by weight of "Epiclon" 1050 as the epoxy resin, and 3 weights of "Placcel" (registered trademark) CD210 as the polycarbonate polyol A back surface protective sheet for a solar cell module was produced in the same manner as in Example 2 except that the part was used. Although the adhesion strength after 1000 hours at 85 ° C. × 85% RH was slightly reduced due to the small amount of polycarbonate polyol added, there was no practical problem.

(Example 8)
A back protective sheet for a solar cell module was prepared in the same manner as in Example 1 except that the resin component of the adhesive was 7 parts by weight of “Desmodule” (registered trademark) N3300 as a polyisocyanate compound. Since the addition amount of the polyisocyanate compound was small, the initial adhesion strength, 85 ° C. × 85% RH, and adhesion strength after 1000 hours were both low, but there was no problem in practical use.

Example 9
In Example 8, a back protective sheet for a solar cell module was produced in the same manner as in Example 2 except that 35 parts by weight of “Desmodule” (registered trademark) N3300 was used.

  Due to the large amount of polyisocyanate compound added, the curing rate of the adhesive was as low as 52%, and the initial adhesive strength, 85 ° C. × 85% RH, and the adhesive strength after 1000 hours were both low, It was a level that could be used somehow in practice.

(Example 10)
Example 1 except that the resin component of the adhesive was "Beccolite" (registered trademark) M-6180-50 as the polyester polyol and 0.5 parts by weight of "Carbodilite" (registered trademark) V-07 as the carbodiimide compound. The back surface protection sheet for solar cell modules was produced similarly to. Although the addition amount of the carbodiimide compound was small and the initial adhesion strength was high, the adhesion strength after 1000 hours at 85 ° C. × 85% RH was low.

(Comparative Example 1)
In Example 1, the back surface protection sheet for solar cell modules was produced by not adding a hardening acceleration | stimulation catalyst and making all other conditions the same as Example 1. FIG.
Without the addition of a curing accelerating catalyst, the curing rate of the adhesive was as low as 23% when aging at 25 ° C. for 72 hours, and the initial adhesion strength, 85 ° C. × 85% RH, and adhesion strength after 1000 hours were both insufficient. there were.

(Comparative Example 2)
In Comparative Example 1, the aging conditions were 45 ° C. and 72 hours. Curing progressed and the curing rate of the adhesive was 84%, and the adhesion strength was sufficient, but the curl was as large as 18 mm, and it could not be used.

(Comparative Example 3)
In Example 1, the aging conditions were 18 ° C. and 96 hours. Curing was insufficient and the adhesion strength was also insufficient.

(Comparative Example 4)
In Example 1, the aging conditions were 25 ° C. and 36 hours. Curing was insufficient and the adhesion strength was also insufficient.

(Comparative Example 5)
In Example 1, the aging conditions were 45 ° C. and 36 hours. The curl was as large as 16 mm and was not practical.

10: Back surface protection sheet for solar cell module 11: Thermal adhesive resin film 12: A layer of thermal adhesive resin film 13: B layer of thermal adhesive resin film 14: C layer of thermal adhesive resin film 15: Adhesive 16: Plastic film 22: EVA sheet layer 1
23: EVA sheet layer 2
24: Glass plate 25: Photovoltaic power generation element as a photovoltaic element provided with wiring

Claims (7)

A back protective sheet for a solar cell module, in which a plastic film and a heat-adhesive resin film are bonded together with an adhesive, wherein adhesion strength between film layers is 2 N / 15 mm or more, and curl is 10 mm or less. Back protection sheet for solar cell modules. The adhesive is 5 to 30 parts by weight of the epoxy resin (b), 5 to 30 parts by weight of the polycarbonate polyol (c), 1 to 10 parts by weight of the carbodiimide compound (d), and 100 parts by weight of the polyester polyol (a). The back protective sheet for a solar cell module according to claim 1, wherein 10 to 30 parts by weight of an isocyanate compound (e) and 0.002 to 1 part by weight of a curing accelerating catalyst (f) are blended. . The back surface protective sheet for a solar cell module according to claim 2, wherein the curing accelerating catalyst (f) is zinc stearate. The back surface protection sheet for solar cell modules according to any one of claims 1 to 3, wherein the curing rate of the adhesive is 70% or more. The back surface protective sheet for a solar cell module according to any one of claims 1 to 4, wherein the adhesion strength between the film layers is maintained at 2 N / 15 mm after being stored for 1000 hours under the condition of 85 ° C x 85% RH.   It is a manufacturing method of the back surface protection sheet for solar cell modules in any one of Claims 1-5, Comprising: A plastic film and a thermoadhesive resin film are epoxy resins with respect to 100 weight part of polyester polyols (a). (B) 5-30 parts by weight, polycarbonate polyol (c) 5-30 parts by weight, carbodiimide compound (d) 1-10 parts by weight, polyisocyanate compound (e) 10-30 parts by weight, and curing accelerating catalyst (f) A method for producing a back surface protective sheet for a solar cell module, comprising: bonding with an adhesive containing 0.002 to 1 part by weight; and aging at a temperature of 20 ° C. or more and less than 40 ° C. for 48 hours or more after bonding. It is a manufacturing method of the solar cell module using the back surface protection sheet for solar cell modules in any one of Claims 1-5, Comprising: As a direction in which this thermoadhesive resin film surface faces an EVA sheet layer, for solar cell modules A photovoltaic element / EVA sheet layer / glass plate as a photovoltaic element provided with a back surface protective sheet / EVA sheet layer / wiring is laminated in this order, and these layers are thermocompression-molded as an integrally formed body, A method for manufacturing a solar cell module, comprising mounting a frame.

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