JP2015138900A - Protective sheet for solar batteries, and solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protective sheet for solar batteries and a solar battery module which are superior in durability and enable the rise in the production efficiency.SOLUTION: A protective sheet 1 for solar batteries comprises: a base 11; a tie layer 12 stacked on one surface of the base; and a sealant adhesion layer 13 stacked thereon. The base 11 is formed from a film of polyester-based material. As to polyester that the polyester-based material includes, the terminal carboxyl group concentration is 40 eq./ton or less. The tie layer 12 is formed from an adhesive composition (α) including a hydroxyl group terminal urethane prepolymer (A) and an isocyanate component (B). The hydroxyl group terminal urethane prepolymer (A) has an ether linkage in a main chain, and a (meth) acryloyl group. The adhesive composition(α) includes one or more terpene phenol components (C) selected from a group consisting of terpene phenol resins and their water additives.

Description

  The present invention relates to a solar cell protective sheet used as a surface protective sheet or a back surface protective sheet of a solar cell module, and a solar cell module including the solar cell protective sheet.

  Solar cell modules that convert solar light energy into electrical energy are attracting attention as a clean energy source that can generate electricity without emitting carbon dioxide in response to environmental problems such as air pollution and global warming.

In general, a solar cell module is generally composed of a glass plate, a photoelectric conversion cell, a sealing material, and a back surface protection sheet (back sheet). When the cell is flexible, a surface protective sheet (front sheet) is used instead of the glass plate.
For example, the solar cell module is obtained by stacking a sealing material, a photoelectric conversion cell, a sealing material, and a back surface protection sheet in this order on a glass plate, removing bubbles under vacuum, and further heating at 120 to 150 ° C. Integrated.

  In order to reduce the possibility that the solar cell protective sheet such as the back surface protective sheet or the surface protective sheet peels off from the encapsulant, the most proximate to the encapsulant when incorporated in the solar cell module in the solar cell protective sheet In some cases, the layer becomes a layer having heat-fusibility to the sealing material. In this specification, the solar cell protective sheet is a layer that is closest to the encapsulant when incorporated in the solar cell module, and has a layer having heat-fusibility to the encapsulant. It is called an adhesive layer.

  As a specific example of such a protective sheet for a solar cell, an adhesive having an isocyanate group-containing polymer as a crosslinking agent on one side of a laminated sheet in which a hydrolysis-resistant resin film, a water vapor blocking resin film and a white resin film are laminated. A layer and a thermoadhesive resin layer (encapsulant adhesive layer) containing an ethylene copolymer resin are disclosed in this order (for example, Patent Document 1).

  Here, the solar cell module is required to have a long-term durability, specifically, that the appearance is not deteriorated and the power generation efficiency is not significantly lowered even when used for a long time. The solar cell protective sheet disposed in the outermost layer of the solar cell module is superior in that the solar cell module is resistant to internal destruction of each layer constituting the sheet and peeling between the laminated layers over a long period of time. It is required as a specific characteristic for achieving durability.

In particular, as disclosed in the above-mentioned Patent Document 1, there is a possibility that the resin film constituting the substrate (a laminated sheet of a plurality of films in the above-mentioned Patent Document 1) and the substrate peel from the sealing material adhesive layer. In the solar cell protective sheet provided with a tie layer (adhesive layer in the above-mentioned Patent Document 1) provided for reduction, the material constituting the tie layer deteriorates with time and the base material peels from the sealing material adhesive layer. The possibility increases, and as a result, the durability of the protective sheet for solar cells may be reduced. For this reason, it is calculated | required that the protection sheet for solar cells provided with said structure respond | corresponds appropriately with the problem of a time-dependent deterioration of the material which comprises this tie layer.
As a technique for solving such a problem of deterioration over time, for example, an adhesive for forming a tie layer, which is disclosed in Patent Document 2, is less likely to cause a decrease in cohesive force over time even under wet heat conditions. It can be considered to be used as a material.

JP 2009-200388 A JP 2012-67278 A

  However, when the adhesive disclosed in Patent Document 2 is applied as it is as a material constituting the tie layer of the solar cell protective sheet, the following problems have been revealed by the inventors' investigation. .

  As described above, the solar cell module is manufactured through a heating process at 120 to 150 ° C. However, when the tie layer has insufficient cohesive force, the tie layer is deformed by heat, and the tie layer is destructed, Interfacial destruction with the base material or the sealing material adhesive layer may occur.

  In order to increase the cohesive strength of the tie layer, it is necessary to sufficiently advance the curing reaction of the adhesive composition, and it is effective to cure the protective sheet for solar cells in a high temperature environment. When performed in a high temperature environment, the solar cell protective sheet is curled during the curing process due to the difference in thermal shrinkage between the base material and the sealing material adhesive layer. Will be formed.

  Therefore, in order to avoid this curling, the most realistic countermeasure is to reduce the environmental temperature in the curing process. However, when the curing process is performed in a low temperature environment of about room temperature, the curing period of the tie layer formed using the adhesive disclosed in Patent Document 2 is particularly long, and the production efficiency is lowered.

  Against this background, the present invention aims to provide a solar cell protective sheet that has excellent durability and can increase production efficiency, and a solar cell module including the solar cell protective sheet. To do.

  The present inventors have studied to achieve the problem of having excellent durability and increasing production efficiency. The material constituting the tie layer has a hydroxyl group terminal having an ether bond and a (meth) acryloyl group in the main chain. The present inventors have obtained new knowledge that the above problems can be solved by using an adhesive composition formed from a urethane prepolymer and an isocyanate component and further containing a terpene phenol component in the adhesive composition. In the present specification, the (meth) acryloyl group means both an acryloyl group and a methacryloyl group. The same applies to similar terms such as (meth) acrylate.

  The present invention completed on the basis of such knowledge, firstly, a base material, a tie layer laminated on one surface of the base material, and a surface opposite to the side of the tie layer facing the base material A protective sheet for a solar cell comprising a sealing material adhesive layer laminated on the substrate, wherein the base material is formed from a film of a polyester material, and the polyester contained in the polyester material has a terminal carboxyl group concentration The tie layer is formed from an adhesive composition containing a hydroxyl group-terminated urethane prepolymer and an isocyanate component, and the hydroxyl group-terminated urethane prepolymer has an ether bond as a main chain. And a (meth) acryloyl group, and the adhesive composition comprises a terpene phenol resin and a hydrogenated compound thereof. A protective sheet for a solar cell, characterized by containing one or two or more terpene phenolic component selected from (invention 1).

  Since the hydroxyl group-terminated urethane prepolymer contained in the adhesive composition according to the invention has an ether bond in the main chain, the resin component containing the hydroxyl group-terminated urethane prepolymer in the tie layer formed from the adhesive composition (Hereinafter abbreviated as “resin component”) is relatively less susceptible to hydrolysis even under wet heat conditions. In addition, the (meth) acryloyl group possessed by the urethane prepolymer supplements radical species that decompose the resin component in the tie layer to lower the molecular weight, or the (meth) acryloyl groups are polymerized with each other. The resin component in the tie layer can be made difficult to lower the molecular weight. Accordingly, the cohesive force of the tie layer is unlikely to decrease due to the low molecular weight of the resin component in the tie layer.

  The terpene phenol component contained in the adhesive composition chemically interacts with the material present on the side of the substrate facing the tie layer, so that the phenolic hydroxyl group is between the tie layer and the substrate. Interfacial peeling can be made difficult to occur. In addition, the terpene phenol component can increase the cohesive strength of the tie layer at the stage of drying the coating film of the adhesive composition (also referred to as “immediately after tie layer formation” in this specification). Since the cohesive force is high even when the curing reaction is not progressing sufficiently, the curing period when producing the tie layer can be shortened.

  In the said invention (invention 1), it is preferable that the said terpene phenol component has a softening point of 80 degreeC or more (invention 2). When the softening point of the terpene phenol component satisfies the above range, the cohesive force of the tie layer immediately after tie layer formation can be more stably increased.

  In the above inventions (Inventions 1 and 2), the total amount of the product of the content of the terpene phenol component with respect to 100 parts by mass of the hydroxyl-terminated urethane prepolymer and the hydroxyl value of the terpene phenol component (this total amount is referred to in this specification) The “hydroxyl amount” is also preferably 50 parts by mass · mg KOH / g or more and 20000 parts by mass · mg KOH / g or less (Invention 3). When the amount of the hydroxyl group satisfies the above range, the chemical interaction between the base material and the tie layer occurs more stably, and the possibility that the base material peels from the tie layer is further reduced.

  In the said invention (invention 1 to 3), it is preferable that the said sealing material contact bonding layer contains polyolefin resin (invention 4). Since polyolefin-based resins are not easily decomposed, particularly hydrolyzed, they are less likely to deteriorate over time such as cohesive failure of the sealing material adhesive layer.

  Second, the present invention is a solar cell module comprising a solar cell, a sealing material that encloses the solar cell, and two protective members stacked on each of the main surfaces of the sealing material, At least one of the protective members is provided with a solar cell protective sheet according to any one of the first to fourth aspects of the invention (invention 5).

  The solar cell protective sheet according to the present invention has high production efficiency because the base material of the sheet is difficult to peel off from the sealing material adhesive layer even under wet heat conditions, and the curing period is short in the production of the sheet. . A solar cell module including the solar cell protective sheet having excellent durability and productivity is excellent in durability and price competitiveness based on the above-described characteristics of the sheet.

  According to this invention, since the resin component in the tie layer with which the protection sheet for solar cells is provided is hard to make low molecular weight, durability is high. Moreover, since the adhesive composition contains a terpene phenol component, interfacial peeling is unlikely to occur between the base material and the tie layer, and the cohesive force is high even if the curing reaction is not sufficiently progressed. A period can be shortened and it can put into the manufacturing process of a solar cell module. Therefore, the solar cell protective sheet according to the present invention has excellent durability and high production efficiency. Moreover, a solar cell module provided with this protective sheet for solar cells is excellent in durability and price competitiveness.

It is a schematic sectional drawing of the protection sheet for solar cells which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the solar cell module which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the solar cell module which the surface protection sheet and back surface protection sheet which concern on other embodiment of this invention consist of the protection sheet for solar cells which concerns on this embodiment.

EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.
1. Protective sheet for solar cell As shown in FIG. 1, a protective sheet 1 for a solar cell according to this embodiment includes a base material 11 and a tie layer laminated on one surface of the base material 11 (upper surface in FIG. 1) 12 and a sealing material adhesive layer 13 laminated on the side opposite to the side of the tie layer 12 facing the substrate 11. In this solar cell protective sheet 1, the sealing material adhesive layer 13 functions as a layer for reducing the possibility of peeling when the solar cell protective sheet 1 is laminated on the sealing material. The battery protection sheet 1 is used as a surface protection sheet (front sheet) or a back surface protection sheet (back sheet) of a solar cell module.

(1) Base material The base material 11 with which the protection sheet 1 for solar cells which concerns on this embodiment is provided is formed from the film of a polyester-type material. Here, the polyester-based material is a material containing, as a main component, polyester which is a polymer having an ester bond in the skeleton portion. Such a polyester can be obtained by copolymerizing a diol and a dicarboxylic acid.

  Specific examples of the diol include ethylene glycol and 1,4-butanediol. Specific examples of the dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid. What is necessary is just to select suitably the combination of these diol and dicarboxylic acid so that the polymer (polyester resin) obtained may have the characteristic mentioned later.

  Typical polyesters include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and the like. Among these polyesters, polyethylene terephthalate is preferable because it is excellent in basic characteristics, inexpensive and excellent in availability.

  The polyester contained in the polyester material according to the present embodiment has a terminal carboxyl group concentration of 40 equivalents / ton or less. When the terminal carboxyl group concentration is 40 equivalents / ton or less, it becomes easy to obtain the substrate 11 having excellent hydrolysis resistance. From the viewpoint of further increasing the hydrolysis resistance of the substrate 11, the above terminal carboxyl group concentration is preferably 30 equivalents / ton or less, and more preferably 25 equivalents / ton or less. The lower limit of the terminal carboxyl group concentration is not particularly limited from the viewpoint of enhancing the hydrolysis resistance of the substrate 11. If it is excessively low, there is a concern that the production efficiency of the polyester is lowered. Therefore, from the viewpoint of avoiding the occurrence of this problem, it is preferably about 5 equivalents / ton or more. In the present specification, a polyester material in which the terminal carboxyl group concentration of the polyester contained is 40 equivalents / ton or less is referred to as “hydrolysis-resistant polyester”.

  As described above, among the polyesters, polyethylene terephthalate is preferable from the viewpoint of availability stability and the like. Therefore, the hydrolysis-resistant polyester constituting the substrate 11 according to this embodiment is a hydrolysis-resistant polyethylene containing polyethylene terephthalate as the polyester. It is preferably terephthalate (hereinafter also referred to as “hydrolysis-resistant PET”).

  In addition, the base material 11 may contain various additives, such as a pigment, an ultraviolet absorber, an ultraviolet stabilizer, a flame retardant, a plasticizer, an antistatic agent, a lubricant, and an antiblocking agent, as necessary. Examples of the pigment include titanium dioxide and carbon black. Examples of the ultraviolet absorber include benzophenone series, benzotriazole series, oxalic acid anilide series, cyanoacrylate series, and triazine series.

  Here, when using the solar cell protective sheet 1 according to the present embodiment as a back surface protective sheet of a solar cell module, the substrate 11 preferably contains a pigment that reflects visible light. Moreover, when using the solar cell protective sheet 1 according to this embodiment as a surface protective sheet of a solar cell module, it is preferable not to contain a pigment that reduces the light transmittance in the visible light region, and the weather resistance is improved. For the purpose, it is more preferable to contain an ultraviolet absorber.

  The thickness of the base material 11 is appropriately set based on electrical insulation required for the solar cell module. The thickness is preferably 10 μm or more and 300 μm or less. More specifically, when the substrate 11 is made of a hydrolysis-resistant PET film, the thickness thereof is 10 μm or more and 300 μm or less from the viewpoint of improving electrical insulation and improving weight reduction. Is more preferably 20 μm or more and 250 μm or less, and particularly preferably 30 μm or more and 200 μm or less.

(2) Tie layer The tie layer 12 provided in the solar cell protective sheet 1 according to the present embodiment is disposed between the base material 11 and the sealing material adhesive layer 13, and the base material 11 is the sealing material adhesive layer. 13 to make it difficult to peel off. The tie layer 12 according to the present embodiment is formed from an adhesive composition (α) containing a hydroxyl group-terminated urethane prepolymer (A) and an isocyanate component (B). The hydroxyl group-terminated urethane prepolymer (A) contained in the adhesive composition (α) has an ether bond in the main chain and a (meth) acryloyl group. Moreover, adhesive composition ((alpha)) contains a terpene phenol component (C).

(2-1) Hydroxyl-terminated urethane prepolymer (A)
The hydroxyl group-terminated urethane prepolymer (A) contained in the adhesive composition (α) is a major type of component that gives the resin component of the tie layer 12 in the adhesive composition (α), and has an ether bond. Has in the main chain. Therefore, the resin component of the tie layer 12 formed from the adhesive composition (α) also has an ether bond in the main chain. Since the ether bond is excellent in hydrolysis resistance, particularly hydrolysis resistance under wet heat conditions, the tie layer 12 formed from the adhesive composition (α) containing the hydroxyl group-terminated urethane prepolymer (A) has high heat resistance. Deterioration with time under conditions is unlikely to occur.

  The hydroxyl group-terminated urethane prepolymer (A) contained in the adhesive composition (α) contains a (meth) acryloyl group. Even if a radical species that decomposes the resin component in the tie layer 12 may be generated in the tie layer 12 due to the wet heat condition of the solar cell protective sheet 1 according to the present embodiment, the hydroxyl-terminated urethane prepolymer (A). The derived (meth) acryloyl group can capture the generated radical species. For this reason, in the tie layer 12 according to the present embodiment, the decomposition reaction of the resin component based on the radical species hardly occurs.

  In addition, even if the resin component is decomposed by the radical species generated in the tie layer 12, the (meth) acryloyl group of the decomposed resin component has an undecomposed resin component in the tie layer 12 (meth). As a result, it is possible to prevent the molecular weight of the resin component from being lowered, for example, by polymerization with an acryloyl group.

  By exhibiting these functions by the (meth) acryloyl group, the resin component in the tie layer 12 is not easily lowered in molecular weight even under wet heat conditions. When the resin component is decomposed and the low molecular weight component is increased, the cohesive force of the tie layer 12 is reduced, and the tie layer 12 is likely to cohesively break. Therefore, the tie layer 12 according to the present embodiment hardly deteriorates with time even under wet heat conditions.

  The hydroxyl group-terminated urethane prepolymer (A) may contain at least one of an acryloyl group and a methacryloyl group as a (meth) acryloyl group. From the viewpoint that the function of the (meth) acryloyl group is appropriately exhibited, The (meth) acryloyl group is preferably a methacryloyl group.

  The hydroxyl group-terminated urethane prepolymer (A) can be obtained by reacting an active hydrogen component comprising a diol (x) having a (meth) acryloyl group and a polyether polyol (a) with an isocyanate component (B).

  Examples of the diol (x) having a (meth) acryloyl group include trivalent groups such as trimethylolpropane, glycerin, 3-hydroxy-1,5-pentanediol and 2-hydroxy-2-ethyl-1,3-propanediol. Mono (meth) acrylate of alcohol or an alkylene oxide thereof (hereinafter abbreviated as “AO”) 1 to 30 mol adduct; pentaerythritol or di (meth) acrylate of 1 to 30 mol adduct of AO; dipentaerythritol Or the tetra (meth) acrylate of the AO1-30 mol adduct, etc. are mentioned.

  Examples of AO include ethylene oxide (hereinafter abbreviated as “EO”), 1,2- or 1,3-propylene oxide (hereinafter abbreviated as “PO”), and 1,2-, 1,3. -, 1,4- or 2,3-butylene oxide (hereinafter abbreviated as “BO”, but 1,4-butylene oxide may be abbreviated as “THF” (tetrahydrofuran)), etc. ˜4 AO and the like.

  Among these, glycerin monomethacrylate, trimethylolpropane monomethacrylate and pentaerythritol dimethacrylate are particularly preferable from the viewpoint of improving the durability of the obtained tie layer 12.

  The diol (x) having a (meth) acryloyl group may be used alone or in combination of two or more.

  Examples of the polyether polyol (a) include polyether diols, trifunctional or higher functional polyether polyols, and those obtained by coupling one or more of these with methylene dichloride. Specific examples of the polyether diol include poly (oxyalkylene) glycols such as poly (oxyethylene) glycol, poly (oxypropylene) glycol and poly (oxytetramethylene) glycol, poly (oxy-3-methyltetramethylene) glycol; EO / PO copolymerized diol, THF / EO copolymerized diol, THF / 3-methyltetrahydrofuran copolymerized diol and the like (weight ratio is, for example, 1/9 to 9/1); poly (oxyalkylene) diol; and bisphenol A And AO adducts of bisphenol compounds such as bisphenol B, bisphenol E, and bisphenol F. Specific examples of the tri- or higher functional polyether polyol include an AO adduct of a trihydric or higher polyhydric alcohol such as an AO adduct of glycerin and an AO adduct of trimethylolpropane.

  Of the polyether polyol (a), an AO adduct of a bisphenol compound, a tri- or higher functional polyether polyol, and a polyether polyol having a chemical formula weight or a number average molecular weight excluding one or more of them coupled with methylene dichloride (Hereinafter abbreviated as “Mn”) is preferably 200 to 3,000. In the present invention, Mn is measured by gel permeation chromatography using THF as a solvent and polyethylene glycol as a standard substance.

  From the viewpoint of increasing the cohesive strength of the tie layer 12, the AO addition mole number in the AO adduct of the bisphenol compound is preferably 2 to 10 mol, more preferably 2 to 6 mol, and 2 to 4 mol. It is particularly preferable that In addition, the number of moles of AO added in the AO adduct of a trihydric or higher polyhydric alcohol is preferably 2 to 100 moles from the viewpoint of making it difficult for delamination between the tie layer 12 and the substrate 11 to occur. More preferably, the molar amount is 2 to 30 mol.

  Polyether polyol (a) may be used individually by 1 type, or may use 2 or more types together.

  Of these, poly (oxytetramethylene) glycol is preferable from the viewpoint of increasing the durability of the tie layer 12, and AO adducts of bisphenol compounds, particularly bisphenol A, are preferable from the viewpoint of increasing the cohesive strength of the tie layer 12. The EO adduct is preferably a combination of poly (oxytetramethylene) glycol and an AO adduct of a bisphenol-based compound from the viewpoint of improving both durability and cohesive strength of the tie layer 12. When poly (oxytetramethylene) glycol and an AO adduct of a bisphenol compound are used in combination, the mass ratio of poly (oxytetramethylene) glycol to an AO adduct of a bisphenol compound is 30:70 to 95: 5 is preferable, 40:60 to 90:10 is more preferable, and 50:50 to 85:15 is particularly preferable.

  The amount of the diol (x) having a (meth) acryloyl group in the above active hydrogen component is selected from the viewpoint of increasing the durability of the tie layer 12 and the storage stability of the adhesive composition (α). The number of moles of the diol (x) having a (meth) acryloyl group with respect to the total mass of the urethane prepolymer (A) and the isocyanate component (B) is preferably 10 to 1,000 mmol / kg, More preferably, the amount is ˜600 mmol / kg, and particularly preferably 30 to 400 mmol / kg.

  The amount of the polyether polyol (a) used in the active hydrogen component is preferably 50 to 99.9% by mass based on the mass of the active hydrogen component from the viewpoint of enhancing the durability of the tie layer 12.

  As an isocyanate component used for the production of the hydroxyl group-terminated urethane prepolymer (A), the aliphatic isocyanate (b1) having 2 to 18 carbon atoms (excluding carbon in the isocyanate group, the same shall apply hereinafter), and having 4 to 15 carbon atoms. Alicyclic isocyanate (b2), araliphatic isocyanate having 8 to 15 carbon atoms (b3), aromatic isocyanate having 6 to 20 carbon atoms (b4) and their isocyanurate groups, uretoimine groups, allophanate groups, biuret groups, Examples thereof include an isocyanate-modified product having a uretoimine group, a carbodiimide group, and a uretdione group, and a reaction product (b5) of the above (b1) to (b4) with a tri- to octavalent polyhydric alcohol.

  Examples of the aliphatic isocyanate (b1) having 2 to 18 carbon atoms include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (hereinafter abbreviated as “HDI”), heptamethylene diisocyanate, octamethylene diisocyanate, decamethylene diisocyanate, and dodeca. Methylene diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcaproate, 2,6-diisocyanatoethylcaproate, bis (2- And isocyanatoethyl) fumarate and bis (2-isocyanatoethyl) carbonate.

  Examples of the alicyclic isocyanate (b2) having 4 to 15 carbon atoms are isophorone diisocyanate (hereinafter abbreviated as “IPDI”), dicyclohexylmethane-4,4′-diisocyanate (hereinafter abbreviated as “hydrogenated MDI”). ), Cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis (2-isocyanatoethyl) -4-cyclohexylene-1,2-dicarboxylate and 2,5- or 2,6-norbornane diisocyanate.

  Examples of the araliphatic isocyanate having 8 to 15 carbon atoms (b3) include m- or p-xylylene diisocyanate (hereinafter abbreviated as “XDI”), diethylbenzene diisocyanate and α, α, α ′, α′-tetra. Methylxylylene diisocyanate (hereinafter abbreviated as “TMXDI”) and the like.

  Examples of the aromatic isocyanate (b4) having 6 to 20 carbon atoms include 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate (hereinafter abbreviated as “TDI”). 4,4′- or 2,4′-diphenylmethane diisocyanate (hereinafter abbreviated as “MDI”), m- or p-isocyanatophenylsulfonyl isocyanate, 4,4′-diisocyanatobiphenyl, 3,3 Examples include '-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane and 1,5-naphthylene diisocyanate.

  Isocyanurate group, uretoimine group, allophanate group, biuret group, uretoimine group, carbodiimide group, reaction product of isocyanate modified product having 3 to 8 valent polyhydric alcohol and (b1) to (b4) (b5) ) Include a modified product having a uretoimine group of MDI, a modified product having a biuret group of HDI, a modified product having an isocyanurate group of HDI, and a reaction product of HDI with trimethylolpropane.

  From the viewpoint of enhancing the curability of the adhesive composition (α), the average number of functional groups of the hydroxyl group of the hydroxyl group-terminated urethane prepolymer (A) is preferably 2-6 or more, more preferably 2-5, It is particularly preferably 2 to 4, and most preferably 2 to 3.

  The weight average molecular weight (hereinafter abbreviated as “Mw”) of the hydroxyl group-terminated urethane prepolymer (A) is preferably 10,000 or more and 50,000 or less. When the Mw of the hydroxyl group-terminated urethane prepolymer (A) is within this range, a tie layer 12 that is difficult to cohesively break even under wet heat conditions and has excellent adhesion to the substrate 11 at room temperature is obtained. It becomes easy. From the viewpoint of further reducing the possibility of causing the above-described cohesive failure, the Mw of the hydroxyl group-terminated urethane prepolymer (A) is particularly preferably 15,000 or more. From the viewpoint of further improving the adhesion at room temperature, it is particularly preferable that Mw of the hydroxyl group-terminated urethane prepolymer (A) is 30,000 or less.

  Mw in the present invention is measured by gel permeation chromatography using THF as a solvent and polystyrene as a standard substance.

  As a method for producing the hydroxyl group-terminated urethane prepolymer (A) contained in the adhesive composition (α), known urethane production methods can be used. For example, a method of reacting an active hydrogen component and an isocyanate component in the presence or absence of a solvent can be mentioned. Solvents include aromatic solvents such as toluene and xylene; ester solvents such as ethyl acetate and butyl acetate; amide solvents such as dimethylformamide; ketone solvents such as acetone and methyl ethyl ketone; ether solvents such as tetrahydrofuran. Illustrated.

  The equivalent ratio of the isocyanate component to the active hydrogen component (NCO / active hydrogen ratio) is usually 0.25 / 1 to 0.99 / 1 from the viewpoint of easily obtaining a urethane prepolymer having a terminal hydroxyl group. It is preferably 5/1 to 0.95 / 1, more preferably 0.6 / 1 to 0.9 / 1, and particularly preferably 0.7 / 1 to 0.85 / 1. .

(2-2) Isocyanate component (B)
The adhesive composition (α) contains an isocyanate component (B). The isocyanate component (B) contained in the adhesive composition (α) is the main component that provides the resin component in the tie layer 12 in the adhesive composition (α) together with the hydroxyl-terminated urethane prepolymer (A). It is a kind. An isocyanate component (B) may be used individually by 1 type, or may use 2 or more types together. Also, the isocyanate component for forming the hydroxyl group-terminated urethane prepolymer (A) and the isocyanate component (B) contained in the adhesive composition (α) for curing the hydroxyl group-terminated urethane prepolymer (A) The composition may be the same or the composition may be different.

  From the viewpoint of enhancing the cohesive strength and durability of the obtained tie layer 12 as the isocyanate component (B), the polyhydric alcohol having 3 to 8 valences and the isocyanate (b1), (b2), (b3) and / or (b4) And a modified product having an isocyanurate group of aliphatic isocyanate (especially HDI) or alicyclic isocyanate (especially IPDI and hydrogenated MDI), and HDI (1 mol) of trimethylolpropane (1 mol). ) An adduct and a modified product having an isocyanurate group of HDI (such as HDI trimer) are more preferable.

  From the viewpoint of enhancing the curability of the adhesive composition (α), the average number of functional groups of the isocyanate component (B) contained in the adhesive composition (α) is preferably 2 to 6 or more. 5 is more preferable, and 3 to 4 is particularly preferable.

  The isocyanate group content of the isocyanate component (B) contained in the adhesive composition (α) is usually 0.5 to 50% by mass, preferably 1 to 35% by mass, and 3 to 30% by mass. More preferably, it is 4 to 25% by weight, particularly preferably 12 to 24% by weight.

  The ratio of the equivalent ratio (NCO / active hydrogen ratio) of the isocyanate component (B) and the hydroxyl group-terminated urethane prepolymer (A) in the adhesive composition (α) is preferably 0.7 / 1 to 2/1. The ratio of 0.8 / 1 to 1.5 / 1 is more preferable, the ratio of 0.9 / 1 to 1.3 / 1 is particularly preferable, and the ratio of 1/1 to 1.2 / 1 is Most preferred.

(2-3) Terpene phenol component (C)
The adhesive composition (α) contains a terpene phenol component (C). In this specification, the terpene phenol component (C) is one or two or more compounds selected from the group consisting of terpene phenol resins obtained by copolymerizing terpene monomers and phenol and hydrogenated products thereof. means.

  When the adhesive composition (α) contains the terpene phenol component (C), the terpene phenol component (C) contained in the tie layer 12 formed from the adhesive composition (α) has a phenolic hydroxyl group. Further, the material that is in contact with the tie layer 12 in the member that is in contact with the tie layer 12 such as the base material 11 chemically interacts with the material and the adhesion of the tie layer 12 to the base material 11 is improved. Therefore, when adhesive composition ((alpha)) contains a terpene phenol component (C), possibility that interface peeling will arise between the tie layer 12 and the base material 11 etc. will be reduced.

  In addition, the terpene phenol component (C) increases the cohesive strength of the tie layer 12, so that the coating film obtained by applying the adhesive composition (α) for forming the tie layer 12 is immediately dried (tie tie layer 12). The cohesive strength of the tie layer 12 immediately after the layer formation) is high. For this reason, the difference between the cohesive force that the tie layer 12 included in the solar cell protective sheet 1 should have and the cohesive force of the tie layer 12 immediately after tie layer formation is relatively small, and the tie layer 12 immediately after tie layer formation is The amount of the curing reaction of the components contained in the tie layer 12 required for increasing the cohesive force is small. This curing reaction includes a curing reaction between the hydroxyl group-terminated urethane prepolymer (A) and the isocyanate component (B). Since the amount of the curing reaction required is small, the temperature condition of the curing process provided to advance the curing reaction in the tie layer 12 can be about room temperature (23 ° C.), and the curing process It is possible to shorten the time required.

From the viewpoint of more stably realizing the above conditions of the curing process and shortening the curing period, the softening point of the terpene phenol component (C) contained in the tie layer 12 is preferably 80 ° C or higher, and 120 ° C or higher. It is more preferable that The upper limit of the softening point of the terpene phenol component (C) is not particularly limited. However, if it is excessively high, the compatibility between the terpene phenol component (C) and the other components contained in the tie layer 12 decreases, and the tie layer There is a concern that the adhesiveness of the 12 to the substrate 11 or the like may be reduced. Therefore, the softening point of the phenolic hydroxyl group-containing resin is preferably 160 ° C. or lower, and more preferably 130 ° C. or lower.
The softening point is a value measured according to the ring and ball method described in ISO 4625: 1980 (JIS K2207: 1996).

  Total amount of product of the content of the terpene phenol component (C) with respect to 100 parts by mass of the hydroxyl-terminated urethane prepolymer (A) and the hydroxyl value of the terpene phenol component (C). Is also preferably 50 parts by mass · mg KOH / g or more and 20000 parts by mass · mg KOH / g or less. When the amount of the hydroxyl group is excessively small, there is a concern that the adhesiveness of the tie layer 12 to the base material 11 and the like is lowered. On the other hand, when the amount of hydroxyl groups is excessively high, the compatibility between the terpene phenol component (C) and other components contained in the tie layer 12 in the tie layer 12 is reduced, and the tie layer 12 has a base 11 or the like. There is a concern that the adhesiveness may decrease. From the viewpoint of more stably increasing the adhesion of the tie layer 12 to the base material 11 and the like, the amount of hydroxyl group is preferably 200 parts by mass / mg KOH / g or more and 8000 parts by mass / mg KOH / g or less, preferably 1500 parts by mass / mg KOH. / G or more and 6000 parts by mass · mgKOH / g or less is more preferable.

  Although the preferable range of the content of the terpene phenol component (C) in the adhesive composition (α) depends on the hydroxyl value of the terpene phenol component (C), it is not clearly defined, but in the adhesive composition (α) When the content of the terpene phenol component (C) is excessively small, it is difficult to obtain the effect of containing the terpene phenol component (C), and excessive content is relatively hydroxyl-terminated urethane prepolymer (A), etc. Since the content of is less, the possibility of cohesive failure of the tie layer 12 is increased. Accordingly, the content of the terpene phenol component (C) in the adhesive composition (α) is preferably about 1 to 100 parts by mass with respect to 100 parts by mass of the hydroxyl group-terminated urethane prepolymer (A).

Although the preferable range of the hydroxyl value of the terpene phenol component (C) depends on the content of the terpene phenol component (C), it is not definitely defined, but when the hydroxyl value of the terpene phenol component (C) is excessively small, The degree of interaction of the terpene phenol component (C) with the base material 11 is reduced, and if it is excessively large, the compatibility of the terpene phenol component (C) with other components in the tie layer 12 is reduced. However, the adhesion of the tie layer 12 to the base material 11 or the like is difficult to increase. Therefore, the hydroxyl value of the terpene phenol component (C) is preferably about 50 to 250 mgKOH / g.
The hydroxyl value of the terpene phenol component (C) is a value measured according to the acetylation method described in ISO 14900: 2001 (JIS K1557-1).

  The Mn of the terpene phenol component (C) is preferably 100 or more and 10,000 or less. When Mn is excessively small, the terpene phenol component (C) tends to volatilize and the composition of the adhesive composition (α) is difficult to stabilize. When Mn is excessively large, the terpene phenol component (C ) And other components in the tie layer 12 are reduced, and the adhesiveness of the tie layer 12 to the base material 11 and the like is hardly increased. From the viewpoint of more stably increasing the adhesion of the tie layer 12 to the base material 11 and the like, Mn is preferably 200 or more and 7000 or less, and more preferably 400 or more and 5000 or less.

(2-4) Other components Adhesive composition ((alpha)) may contain components other than a hydroxyl-terminated urethane prepolymer (A), an isocyanate component (B), and a terpene phenol component (C). Hereinafter, such components will be described.

  The adhesive composition (α) can contain a solvent. When the adhesive composition (α) contains a solvent, handling property and leveling property at the time of application of the adhesive composition (α) are improved. Examples of the solvent that may be contained in the adhesive composition (α) include the same solvents as those exemplified as the solvent that can be used in the production of the hydroxyl group-terminated urethane prepolymer (A).

  From the viewpoint of improving the handling properties of the adhesive composition (α) and the leveling properties of the coating film of the adhesive composition (α), the amount of the solvent used is a hydroxyl-terminated urethane prepolymer (α) in the adhesive composition (α). The total mass of A) and the isocyanate component (B) is preferably 80% by mass or less, and more preferably 10 to 50% by mass.

  Adhesive composition ((alpha)) can contain the hardening accelerator used for normal urethanation reaction as needed for hardening reaction acceleration | stimulation. Examples of the curing accelerator include organic tin compounds such as dibutyltin dilaurate and organic bismuth compounds such as bismuth tris (2-ethylhexanoate). A hardening accelerator may be used individually by 1 type, or may use 2 or more types together.

  Although the usage-amount of a hardening accelerator does not have limitation in particular, 0.0001-with respect to a total of 100 mass parts of the hydroxyl-terminated urethane prepolymer (A) and isocyanate component (B) in adhesive composition ((alpha)). The amount is preferably 0.3 parts by mass, more preferably 0.001 to 0.2 parts by mass, and particularly preferably 0.01 to 0.1 parts by mass.

  The adhesive composition (α) can contain a polymerization inhibitor such as hydroquinone, 4-methoxyphenol, p-benzoquinone for improving storage stability.

  The amount of the polymerization inhibitor used is preferably 1,000 ppm or less, more preferably 1 to 500 ppm, based on the content of the hydroxyl group-terminated urethane prepolymer (A) in the adhesive composition (α). preferable.

  The adhesive composition (α) further contains additives such as antioxidants, ultraviolet absorbers, plasticizers and fillers as long as the desired effects (such as adhesion of the tie layer 12 to the substrate 11) are not impaired. can do. These additives remain in the tie layer 12 as they are or in a modified form, and impart additional properties (such as resistance to ultraviolet rays and block king resistance) to the tie layer 12.

  Antioxidants include triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5-di-t- Hindered phenolic compounds such as butyl-4-hydroxyphenyl) propionate] and 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]; 4-di-t-butylphenyl) phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octylphosphite, bis (2,6-di-t-butylphenyl) pentaerythritol-di -Phosphite and tetrakis (2,4-di-t-butylphenyl) 4,4'-biphenylene-di-phosphonite And phosphoric acid ester compound. An antioxidant may be used individually by 1 type, or may use 2 or more types together.

  The amount of the antioxidant used is a hydroxyl-terminated urethane prepolymer in the adhesive composition (α) from the viewpoint of stably obtaining an antioxidant effect and ensuring adequate adhesion of the tie layer 12 to the substrate 11 and the like. It is preferably 5 parts by mass or less, more preferably 0.05 to 1 part by mass with respect to 100 parts by mass of the total mass of the polymer (A) and the isocyanate component (B).

  Examples of the ultraviolet absorber include salicylic acid derivatives such as phenyl salicylate, salicylic acid-P-octylphenyl and salicylic acid-P-tert-butylphenyl; 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′- Dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxy-5-sulfobenzophenone, 2-hydroxy-4-methoxy-2 '-Carboxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, 2,2', 4 4'-tetrahydride Benzophenone compounds such as xylbenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2-hydroxy-4- (2-hydroxy-3-methacryloxy) propoxybenzophenone and bis (2-methoxy-4-hydroxy-5-benzoylphenyl) methane 2- (2′-hydroxy-5′-methyl-phenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butyl-phenyl) benzotriazole, 2- (2′- Hydroxy-3'-t-butyl-5'-methyl-phenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butyl-phenyl) -5 -Chlorobenzotriazole, 2- (2'-hydroxy-4'-n-octoxyphenyl) benzotriazole, -(2'-hydroxy-5'-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-amylphenyl) benzotriazole, 2- [2'-hydroxy -3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl] benzotriazole and 2,2-methylenebis [4- (1,1,3,3-tetramethyl) Butyl) -6- (2H-benzotriazol-2-yl) phenol]; 2-ethylhexyl-2-cyano-3,3′-diphenyl acrylate and ethyl-2-cyano-3,3′- Examples include cyanoacrylate compounds such as diphenyl acrylate. An ultraviolet absorber may be used individually by 1 type, or may use 2 or more types together.

  The amount of the ultraviolet absorber used is determined from the viewpoint of stably obtaining the ultraviolet absorbing effect and from the viewpoint of appropriately ensuring the adhesion of the tie layer 12 to the base material 11 and the like, in the adhesive composition (α). The amount is preferably 5 parts by mass or less, more preferably 0.1 to 1 part by mass with respect to 100 parts by mass in total of the polymer (A) and the isocyanate component (B).

  Examples of the plasticizer include process oil, liquid polybutadiene, liquid polyisobutylene, liquid polyisoprene, liquid paraffin, chlorinated paraffin, paraffin wax, and copolymerization of ethylene and α-olefin (3 to 20 carbon atoms) (weight ratio: 99. 9 / 0.1 to 0.1 / 99.9) oligomer (weight average molecular weight (hereinafter abbreviated as Mw) 5,000 to 100,000) and α-olefin (carbon number 4 to 20) excluding propylene and ethylene Copolymer (weight ratio 99.9 / 0.1 to 0.1 / 99.9), hydrocarbons such as oligomers (Mw 5,000 to 100,000); chlorinated paraffins; phthalates, adipates, sebatin Esters such as acid esters; animal and vegetable fats and oils such as linoleic acid and linolenic acid; and hydrogenable unsaturated double bonds thereof And hydrogenated substances having a combination of the above. Specific examples of the ester include diethyl phthalate (DEP), dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DOP), didecyl phthalate, dilauryl phthalate, distearyl phthalate and the like. Examples thereof include diisononyl phthalate, and specific examples of adipic acid esters include di (2-ethylhexyl) adipate (DOA) and dioctyl adipate. Specific examples of sebacic acid esters include dioctyl sebacate and the like. A plasticizer may be used individually by 1 type, or may use 2 or more types together.

  The amount of the plasticizer used is a hydroxyl group-terminated urethane prepolymer in the adhesive composition (α) from the viewpoint of appropriately securing the adhesion of the tie layer 12 to the substrate 11 and the like and increasing the cohesive strength of the tie layer 12. It is preferable that it is 100 mass parts or less with respect to a total of 100 mass parts of (A) and an isocyanate component (B), and it is more preferable that it is 0.5-30 mass parts.

  As fillers, carbonates such as magnesium carbonate and calcium carbonate; sulfates such as aluminum sulfate, calcium sulfate and barium sulfate; sulfites such as calcium sulfite; molybdenum disulfide; silicic acids such as aluminum silicate and calcium silicate Salts; diatomaceous earth; quartzite powder; talc; silica and zeolite.

  The filler is preferably fine particles having a volume average particle diameter of about 0.01 to 5 μm, and one kind may be used alone or two or more kinds may be used in combination.

  From the viewpoint of increasing the cohesive strength of the tie layer 12, the amount of filler used is 100 parts by mass in total of the hydroxyl group-terminated urethane prepolymer (A) and the isocyanate component (B) in the adhesive composition (α). The amount is preferably 250 parts by mass or less, and more preferably 0.5 to 100 parts by mass.

(3) Sealing material adhesion layer The sealing material adhesion layer 13 in this embodiment is laminated | stacked on the sealing material in the specific example, and the solar cell protective sheet 1 may peel from a solar cell module. It is for reducing. Since the sealing material adhesive layer 13 is bonded to the sealing material by heat fusion, the material constituting the sealing material adhesive layer 13 has thermoplasticity as a whole, and as an example, the thermoplastic material is a thermoplastic resin. It is brought about by containing.

  The thickness of the sealing material adhesive layer 13 is not particularly limited as long as the sealing material adhesive layer 13 can appropriately have adhesiveness to the sealing material. Specifically, the thickness of the sealing material adhesive layer 13 is preferably 1 μm or more and 200 μm or less, and is 10 μm or more and 180 μm or less from the viewpoint of improving electrical insulation and improving weight reduction. More preferably, it is 50 μm or more and 150 μm or less, and particularly preferably 80 μm or more and 120 μm or less.

(3-1) Thermoplastic Resin The sealing material adhesive layer 13 in the present embodiment may contain a thermoplastic resin, and the sealing material adhesive layer 13 is sealed by thermal fusion based on the thermoplasticity of the thermoplastic resin. It may be fixed to the material. The kind of resin which comprises this thermoplastic resin is not specifically limited. Specific examples of such resins include: polyolefin resins; polyolefin thermoplastic elastomers; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyester thermoplastic elastomers; various thermoplastic elastomers modified by epoxidation; Polyvinyl resin; Polycarbonate resin; Polyamide resin such as nylon 6, nylon 11, nylon 12, nylon 66, nylon 46, aromatic nylon; polyacetal resin; polyarylate resin; polyamideimide resin; Resin; Polyetherketone resin and the like. Organic / inorganic composite resins such as silicone-based thermoplastic elastomers are also exemplified as thermoplastic resins. The thermoplastic resin may be composed of one kind of resin, or may be composed of a plurality of kinds of resins.

  Among these resins, polyolefin resins, that is, homopolymers and copolymers composed of structural units based on olefins, and copolymers containing structural units based on olefins and structural units based on molecules other than olefins. It is preferable that it is a thermoplastic resin containing 1 type or 2 types or more chosen from the group which consists of resin whose mass ratio of the part based on the structural unit based on the olefin in resin after superposition | polymerization is 1.0 mass% or more. The polyolefin resin can further reduce the possibility that the solar cell protective sheet 1 is peeled off from the sealing material due to its excellent heat-sealing action.

Specific examples of the polyolefin resin, high density polyethylene (HDPE, density: 942kg / ^{m 3} or more), medium density polyethylene (MDPE, density: 930 kg / ^{m 3} or more and less than 942kg / ^{m 3),} low density polyethylene (LDPE, density: 910 kg / ^{m 3} or more and less than 930 kg / ^{m 3),} very low density polyethylene (VLDPE, density: 870 kg / ^{m 3} or more and less than 910 kg / ^{m 3),} polyethylene resins such as linear low density polyethylene (PE) , Polypropylene resin (PP), polyethylene-polypropylene polymer, olefin elastomer (TPO), cycloolefin resin, ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl acetate-maleic anhydride copolymer, ethylene- ( (Meth) acrylic acid copolymer, ionomer, Ethylene- (meth) acrylic acid ester copolymer, ethylene- (meth) acrylic acid ester-maleic anhydride copolymer, ethylene- (meth) acrylic acid glycidyl copolymer, ethylene- (meth) acrylic acid ester- ( And a glycidyl acrylate copolymer. Among these, polyethylene resin (PE), polypropylene resin (PP), ethylene-vinyl acetate copolymer (EVA), and ethylene- (meth) acrylic acid copolymer are preferable from the viewpoint of availability.

  Moreover, the thermoplastic resin which concerns on the sealing material contact bonding layer 13 may have a crosslinked structure where a part of polymer which comprises the said resin reacts with a crosslinking agent. The kind of the crosslinking agent that gives this crosslinked structure is arbitrary, and organic peroxides such as dicumyl peroxide, compounds having an epoxy group, and compounds having an isocyanate group are typical. The density of the cross-linked structure, that is, the degree of cross-linking, is arbitrary. However, if this density is excessively high, the sealing material adhesive layer 13 may lose its thermoplasticity, so that such a problem does not occur. It is preferable to make it.

(3-2) Other components The sealing material adhesive layer 13 is formed of a coloring pigment such as titanium dioxide or carbon black, an ultraviolet absorber such as benzophenone, an ultraviolet stabilizer, a flame retardant, a plasticizer, or an antistatic material, as necessary. Various additives such as agents, lubricants and fillers may be included.

  In addition, when the sealing material contact bonding layer 13 contains white pigments, such as a titanium dioxide, the solar cell protective sheet 1 is often used as a back surface protective sheet, and the reflectance of the solar cell protective sheet 1 is then used. Is preferably high.

(4) Other components The solar cell protective sheet 1 according to the present embodiment may include not only the base material 11, the tie layer 12, and the sealing material adhesive layer 13, but also other components. . As an example of such a constituent element, a gas barrier layer can be cited as a means for reducing the transmittance of gas such as water vapor in the protective sheet 1 for solar cells. The gas barrier layer may be laminated on the surface of the base material 11 opposite to the side facing the sealing material adhesive layer 13, or may be laminated between the base material 11 and the sealing material adhesive layer 13. . The specific configuration of the gas barrier layer is not particularly limited. In some cases, silicon oxide, aluminum oxide, or the like may be directly laminated on the base material 11 by vapor deposition or the like. In some cases, it is in the form of a film composed of a laminated body and is laminated on the substrate 11 via an adhesive layer. This adhesive layer may be made of the same material as the tie layer 12.

  A fluororesin layer is mentioned as another example of the other component in the protection sheet 1 for solar cells which concerns on this embodiment. A fluororesin layer is normally laminated | stacked in the position which makes | forms the outermost layer, when it attaches to the solar cell module in the protection sheet 1 for solar cells. The composition is not particularly limited as long as it is a layer containing fluorine, and is composed of, for example, a sheet having a fluorine-containing resin (fluorine-containing resin sheet) or a coating film formed by applying a paint containing a fluorine-containing resin. The

2. The manufacturing method of the protection sheet for solar cells The manufacturing method of the protection sheet 1 for solar cells is not specifically limited. For example, the solar cell protective sheet 1 can be obtained by sequentially laminating the layered body from the layered body that should be closest to the substrate 11.

Hereinafter, a method of laminating the tie layer 12 by applying the adhesive composition (α) to the substrate 11 will be described.
When laminating the tie layer 12 on the substrate 11 by coating, an adhesive composition (α) that is a composition for forming the tie layer is first prepared. The adhesive composition (α) contains a component for forming the tie layer 12 together with a solvent as necessary (for the purpose of adjusting viscosity, for example). The terminal urethane prepolymer (A), the isocyanate component (B) and the terpene phenol component (C) are contained as essential components.

  Next, the prepared adhesive composition (α) is applied to one surface of the substrate 11, and the coating film on the obtained substrate 11 is dried, so that the tie layer 12 is placed on the substrate 11. Can be obtained.

  The method for applying the adhesive composition (α) is arbitrary, and examples include an air doctor coater, a blade coater, a rod coater, a knife coater, a reverse roll coater, a transfer roll coater, a gravure coater, and a kiss roll coater.

  The method of drying the coating film is arbitrary. For example, the coating film may be dried together with the substrate 11 in an oven heated to about 100 ° C., or the solvent contained in the coating film is volatilized by setting the atmosphere as a reduced pressure environment. May be. Or you may leave it in air | atmosphere and dry a coating film.

  The solar cell protective sheet 1 according to the present embodiment can be obtained by laminating the sealing material adhesive layer 13 on the surface of the laminate of the obtained base material 11 and tie layer 12 on the tie layer 12 side. it can. The method for laminating the sealing material adhesive layer 13 is arbitrary. A sealing adhesive layer 13 having a sheet-like shape may be laminated in advance and fixed to the above laminated body by a method such as pressure bonding.

  When the solar cell protective sheet 1 includes components other than the substrate 11, the tie layer 12, and the sealing material adhesive layer 13 (such as the gas barrier layer and the fluororesin layer as described above), Other components may be laminated on the base material 11 before the tie layer 12 is laminated on the base material 11, or a sealing material for the laminate composed of the base material 11 and the tie layer 12. After laminating the adhesive layer 13, other components may be laminated on the base material 11.

  The method for manufacturing the solar cell protective sheet 1 according to the present embodiment is preferably a solar cell protection after the tie layer 12 is laminated so as to be disposed between the base material 11 and the sealing material adhesive layer 13. After all the constituent elements of the sheet 1 are laminated, a curing process for increasing the cohesive force of the tie layer 12 by advancing the curing reaction in the tie layer 12 is provided.

  This curing process is usually performed by placing the laminate including the base material 11, the tie layer 12, and the sealing material adhesive layer 13 in an environment of about room temperature (23 ° C.) for several days. From the viewpoint of increasing productivity, the curing period is preferably short. However, if the curing period is shortened by increasing the curing temperature (for example, about 40 ° C. or more), the base material 11 and the sealing material adhesive layer 13 are used. The laminate including the tie layer 12 curls during the curing period based on the difference in thermal contraction rate. In order to avoid the problem of curling, it is necessary to set the curing temperature to about room temperature as described above. However, the tie layer 12 included in the solar cell protective sheet 1 according to the present embodiment has a terpene phenol component ( Since C) is contained, the cohesive force of the tie layer 12 is high immediately after the tie layer is formed. For this reason, the time required for the tie layer 12 to reach a predetermined cohesive force, that is, the curing period can be shortened. Therefore, the solar cell protective sheet 1 according to this embodiment has a short production period and high production efficiency.

3. Solar Cell Module FIG. 2 is a schematic cross-sectional view of a solar cell module according to an embodiment of the present invention. The solar cell module 10 according to the present embodiment includes a photoelectric conversion cell 2, a sealing material 3 that encloses the photoelectric conversion cell 2, and a glass plate 4 that is laminated on the surface (upper surface in FIG. 2) of the sealing material 3. And the back surface protection sheet (back sheet) 1 laminated | stacked on the back surface (in FIG. 2, lower surface) of the sealing material 3 is provided.

  The material of the sealing material 3 is not particularly limited. From the viewpoint of increasing productivity, ethylene-vinyl acetate copolymer (EVA) is often used as a main material, but in recent years, it has the property of being easily altered by ultraviolet rays, and there is a demand for higher productivity. In some cases, materials other than EVA may be used as a main material because it is not easy to handle. Examples of such materials other than EVA include other polyolefin resins such as ethylene-butyl acrylate copolymer, polyvinyl butyral, urethane resins, ionomer resins, styrene resins, and silicone materials.

  The method for manufacturing the solar cell module 10 is not particularly limited. For example, the glass plate 4, the sealing material 3, the photoelectric conversion cell 2, the sealing material 3, and the back surface protection sheet 1 are laminated in this order, and the entire stack thus obtained is pressed and integrated while heating in a vacuum state. The solar cell module 10 can be manufactured by performing the lamination process.

  In addition, as shown in FIG. 3, you may use the protective sheet 1 for solar cells which concerns on this embodiment instead of the glass plate 4. FIG. At this time, if a flexible substrate is used for the photoelectric conversion cell 2, the solar cell module 10 which has flexibility can be obtained. Thus, by making the solar cell module 10 flexible, it becomes possible to mass-produce by roll-to-roll. In addition, since the flexible solar cell module 10 can be fitted to an object having an arched or parabolic wall surface, it can be installed on a dome-shaped building or a soundproof wall of a highway. Become.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited to these examples. In addition, unless specifically limited below, a part represents a mass part.

[Production Example 1]
In a reaction vessel equipped with a cooling tube, 252 parts by mass of polyoxytetramethylene glycol [trade name “PTMG1000”, manufactured by Mitsubishi Chemical Corporation, Mn: 1,000] as polyether polyol (a) and EO2 of bisphenol A Mole adduct [trade name “New Pole BPE-20T”, manufactured by Sanyo Chemical Industries, Ltd., Mn: 310] was charged in an amount of 108 parts by mass. Subsequently, 500 parts by mass of ethyl acetate, 0.15 parts by mass of hydroquinone monomethyl ether as a polymerization inhibitor and glycerin monomethacrylate as a diol (x) having a (meth) acryloyl group [trade name “Blenmer GLM”, NOF ( Co., Ltd., Mn: 160] 4 parts by mass in a reaction vessel and stirred uniformly, then hydrogenated MDI as an isocyanate component [trade name “Desmodur W”, manufactured by Sumika Bayer Urethane Co., Ltd.] 137 parts by mass Was charged. The liquid in the reaction vessel was mixed with stirring under a nitrogen stream and reacted at 70 to 80 ° C. for 1 hour. Further, 0.2 parts by mass of an organic bismuth compound [trade name “Neostan U-600”, manufactured by Nitto Kasei Co., Ltd.] as a curing accelerator was charged in the reaction vessel, and reacted at 70 to 80 ° C. for 8 hours. A solution (A-1) in which the solid content concentration of the urethane prepolymer having a hydroxyl group at 50% was obtained as a solution containing the hydroxyl group-terminated urethane polymer (A).

[Comparative Production Example 1]
In a reaction vessel equipped with a cooling tube, 304 parts by mass of “PTMG1000” as polyether polyol (a) and 76 parts by mass of “New Pole BPE-20T” were charged, and the mixture was uniformly stirred at 105 ° C. and cooled to 60 ° C. did. Subsequently, 500 parts by mass of ethyl acetate was charged into a reaction vessel and stirred uniformly, and then 120 parts by mass of hydrogenated MDI as an isocyanate component was charged. The liquid in the reaction vessel was mixed with stirring under a nitrogen stream and reacted at 70 to 80 ° C. for 1 hour. Furthermore, 0.2 parts by mass of “Neostan U-600” was charged in a reaction vessel and reacted at 70 to 80 ° C. for 8 hours to have a hydroxyl group at the terminal but not a (meth) acryloyl group. A solution (A-2) having a solid content concentration of 50% was obtained as a solution containing a hydroxyl group-terminated urethane prepolymer (A).

[Adhesive Compositions 1-4 and Comparative Adhesive Compositions 1-3]
A solution containing the number of hydroxyl group-terminated urethane prepolymers (A) shown in Table 1, a terpene phenol resin (C) or an aromatic modified terpene resin (D), an isocyanate component (B), ethyl acetate, and a curing accelerator are blended. Thus, adhesive compositions 1 to 4 and comparative adhesive compositions 1 to 3 of the present invention were obtained.

The details of each component in Table 1 are as follows.
Solution (A-1): a solution containing the hydroxyl group-terminated urethane prepolymer (A) having a solid content concentration of 50% obtained in Production Example 1;
Solution (A-2): a solution containing the hydroxyl group-terminated urethane prepolymer (A) having a solid content concentration of 50% obtained in Comparative Production Example 1;
Terpene phenol resin (C-1): [trade name “YS Polystar K-125”, manufactured by Yasuhara Chemical Co., Ltd., hydroxyl value 200 mg KOH / g, softening point 125 ° C.];
Terpene phenol resin (C-2): [trade name “YS Polystar TH-130”, manufactured by Yasuhara Chemical Co., Ltd., hydroxyl value 60 mg KOH / g, softening point 130 ° C.];
Terpene phenol resin (C-3): [trade name “YS Polystar T-100”, manufactured by Yashara Chemical Co., Ltd., hydroxyl value 60 mg KOH / g, softening point 100 ° C.];
Terpene phenol resin (C-4): [trade name “YS Polystar T-80”, manufactured by Yasuhara Chemical Co., Ltd., hydroxyl value 60 mg KOH / g, softening point 80 ° C.];
Aromatic modified terpene resin (D-1): [trade name “YS Polystar TR-105”, manufactured by Yashara Chemical Co., Ltd., hydroxyl value 0 mg KOH / g, softening point 105 ° C.];
Curing accelerator: Bismuth catalyst [trade name “Neostan U-600” manufactured by Nitto Kasei Co., Ltd.]; and isocyanate component (B-1): Isocyanurate modified product of HDI [trade name “Duranate TKA-100” "Asahi Kasei Chemicals Corporation]].

[Example 1]
The adhesive composition 1 is applied to one surface of a hydrolysis-resistant PET film having a thickness of 125 μm as a base material using a bar coater so that the film thickness after drying is 5 μm. The obtained coating film was dried at 80 ° C. for 1 minute to obtain a laminate composed of a tie layer and a substrate. A film made of a 100 μm thick ethylene-vinyl acetate copolymer (vinyl acetate content 9 mass%) prepared as a sealing material adhesive layer was laminated on the tie layer side surface of the laminate. Thus, a laminate in which the base material, the tie layer, and the sealing material adhesive layer were laminated in this order was obtained.
The laminated body was placed in an environment of 23 ° C. and 50% relative humidity so that the surface on the substrate side faced downward in the vertical direction, and a curing process was performed in which the laminate was allowed to stand for 4 days. The laminated body which the curing process was completed was obtained as a protective sheet for solar cells.

[Example 2]
A solar cell protective sheet was produced in the same manner as in Example 1 except that the adhesive composition 1 was replaced with the adhesive composition 2.

Example 3
A protective sheet for a solar cell was produced in the same manner as in Example 1 except that the adhesive composition 1 was replaced with the adhesive composition 3.

Example 4
A protective sheet for a solar cell was produced in the same manner as in Example 1 except that the adhesive composition 1 was replaced with the adhesive composition 4.

[Comparative Example 1]
A protective sheet for a solar cell was prepared in the same manner as in Example 1 except that the adhesive composition 1 was replaced with the comparative adhesive composition 1.

[Comparative Example 2]
A protective sheet for a solar cell was produced in the same manner as in Example 1 except that the adhesive composition 1 was replaced with the comparative adhesive composition 2.

[Comparative Example 3]
A protective sheet for a solar cell was prepared in the same manner as in Example 1 except that the adhesive composition 1 was replaced with the comparative adhesive composition 3.

[Appearance test]
A test sample of 15 cm × 15 cm was obtained from the obtained solar cell protective sheet. About each test sample, it mounts in a lamination apparatus so that the sealing material adhesive layer side may face upward, and the ethylene-vinyl acetate copolymer (400 micrometers in thickness as a sealing material) on the surface of the sealing material adhesive layer side ( EVA) film [trade name "Ultra Pearl", manufactured by Sanvic Co., Ltd.] is stacked two layers, and further, a 3 mm thick white plate tempered glass [AGC Fabricec Co., Ltd.] as a glass plate for a solar cell. Made]. The stack obtained in this way was subjected to vacuum lamination for 3 minutes in which it was heated to 135 ° C. under vacuum, followed by thermal lamination for 3 minutes under pressure at 135 ° C. for further 3 hours. The pseudo solar cell module was obtained by performing heat treatment for 30 minutes.
About each obtained pseudo solar cell module, the presence or absence of the appearance defect by destruction of a tie layer layer and the interface peeling of a tie layer and a base material or a sealing material adhesion layer was observed with the naked eye. The results are shown in Table 2. In addition, about the comparative examples 1, 2, and 3, the thing which made the curing period 7 days was added and tested.

  The solar cell protective sheet according to the present invention is suitably used, for example, as a surface protective sheet (front sheet) or a back surface protective sheet (back sheet) of a solar cell module.

DESCRIPTION OF SYMBOLS 1 ... Solar cell protective sheet 11 ... Base material 12 ... Tie layer 13 ... Sealing material adhesion layer 2 ... Photoelectric conversion cell 3 ... Sealing material 4 ... Glass plate 10 ... Solar cell module

Claims (5)

A solar cell comprising: a base material; a tie layer laminated on one surface of the base material; and a sealing material adhesive layer laminated on a surface of the tie layer opposite to the side facing the base material Protective sheet for
The base material is formed from a polyester material film, and the polyester contained in the polyester material has a terminal carboxyl group concentration of 40 equivalents / ton or less,
The tie layer is formed from an adhesive composition containing a hydroxyl group-terminated urethane prepolymer and an isocyanate component,
The hydroxyl-terminated urethane prepolymer has an ether bond in the main chain and a (meth) acryloyl group,
The said adhesive composition contains the 1 type, or 2 or more types of terpene phenol component chosen from the group which consists of a terpene phenol resin and those hydrogenated compounds, The protective sheet for solar cells characterized by the above-mentioned.   The solar cell protective sheet according to claim 1, wherein the terpene phenol component has a softening point of 80 ° C. or higher.   The total product of the content of the terpene phenol component with respect to 100 parts by mass of the hydroxyl-terminated urethane prepolymer and the hydroxyl value of the terpene phenol component is 50 parts by mass or more and 20000 parts by mass or less than 20000 parts by mass or mgKOH / g. The solar cell protective sheet according to claim 1 or 2.   The said sealing material contact bonding layer is a protection sheet for solar cells as described in any one of Claim 1 to 3 containing polyolefin resin. A solar cell module, comprising a solar cell, a sealing material enclosing the solar cell, and two protective members stacked on each of the main surfaces of the sealing material,
At least one of the said protection members consists of a protection sheet for solar cells as described in any one of Claim 1 to 4, The solar cell module characterized by the above-mentioned.

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