JP2012174744A - Solar battery backside protective sheet, and solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar battery backside protective sheet which overcomes a problem of the prior art, and which is less expensive and excellent in scratch resistance, solvent resistance, long-term outdoor weathering resistance, long-term moist heat resistance, and steam barrier property, and to provide a solar battery module with the solar battery backside protective sheet used therein.SOLUTION: A solar battery backside protective sheet comprises a weathering-resistant resin layer (1) formed of a weathering-resistant resin composition (1') containing a specific acrylic copolymer (A), a specific polyester or urethane resin (B), a polyisocyanate compound (C), and a pigment (D), a plastic film (2), and an adhesive layer (3), which are stacked in this order.

Description

  The present invention relates to a solar cell back surface protective sheet formed by laminating a weather resistant resin layer, an adhesive layer and a plastic film. Specifically, the present invention relates to a solar cell back surface protective sheet that is inexpensive, has scratch resistance, long-term wet heat resistance, and long-term outdoor weather resistance. Furthermore, this invention relates to the solar cell module which uses the said solar cell back surface protection sheet.

In recent years, solar cells have been attracting attention as a clean energy source free from environmental pollution due to an increase in awareness of environmental problems, and earnestly researched and put into practical use from the viewpoint of using solar energy as a useful energy resource.
There are various types of solar cell elements, and typical examples thereof include a crystalline silicon solar cell element, a polycrystalline silicon solar cell element, an amorphous silicon solar cell element, a copper indium selenide solar cell element, and a compound semiconductor solar. Battery elements and the like are known. Among these, thin-film crystal solar cell elements, amorphous silicon solar cell elements, and compound semiconductor solar cell elements are relatively low cost and can be increased in area, and therefore are actively researched and developed in various fields. ing. Among these solar cell elements, thin film solar cell elements represented by amorphous silicon solar cell elements in which silicon is laminated on a conductive metal substrate and a transparent conductive layer is further formed thereon are lightweight, Since it is rich in impact resistance and flexibility, it is considered promising as a future form of solar cells.

  A simple one of the solar cell modules has a configuration in which a filler and a glass plate are sequentially laminated on both sides of the solar cell element. Since a glass plate is excellent in transparency, weather resistance, and scratch resistance, it is still generally used as a sealing sheet on the solar light receiving surface side. However, on the non-light-receiving surface side that does not require transparency, a solar cell back surface protection sheet (hereinafter referred to as a back surface protection sheet) other than the glass plate has been developed by each company in terms of cost, safety, and workability. It is being replaced.

As the back surface protection sheet, a monolayer film such as a polyester film, a polyester film provided with a metal oxide or non-metal oxide vapor deposition layer, a polyester film, a fluorine-based film, an olefin film, an aluminum foil, etc. The multilayer film which laminated | stacked the film is mentioned.
The back surface protection sheet having a multilayer structure can impart various performances due to the multilayer structure. For example, insulating properties can be imparted by using a polyester film, and water vapor barrier properties can be imparted by using an aluminum foil (see Patent Documents 1 to 3).
What kind of back surface protection sheet is used can be appropriately selected depending on the product and application in which the solar cell module is used.

  However, the polyolefin resin and polyester resin used in these back surface protection sheets do not have sufficient weather resistance outdoors, so the output of the solar cell module may decrease when used for a long period of time, or the solar cell back surface protection There was a problem that the appearance of the sheet was damaged.

  On the other hand, there is known a solar cell back surface protection sheet (Patent Document 4 and Patent Document 5) in which a fluorine film having weather resistance is laminated on the outermost layer of the solar cell back surface protection sheet, that is, the layer farthest from the light receiving surface. It has been.

  However, the fluororesin film has a problem that it is difficult to obtain due to its high price and a small supply amount. Furthermore, the potential problem of dehalogenation is inherent because it contains halogen.

  Therefore, as an alternative to the fluorine film, a solar cell back surface protection sheet (Patent Document 6, Patent Document 7) using a polyester film having a low content of cyclic trimer with excellent heat resistance and moist heat resistance as the outermost layer is proposed. However, the polyester film has insufficient outdoor weather resistance and is very expensive although not as much as the fluororesin film.

  Then, the solar cell back surface protection sheet (patent document 8, patent document 9) which provided the weather resistance by providing the polyester film with a fluorine-type or acrylic coating layer as a weather-resistant layer is proposed. Compared with the film-based solar cell back surface protection sheet, there are advantages in terms of cost and simplicity of the process, but weather resistance, moist heat resistance, scratch resistance, and solvent resistance are still sufficient. It is not the stage to say.

Japanese Patent Laid-Open No. 2004-200322 JP 2004-223925 A JP 2001-119051 A JP 2003-347570 A JP 2004-352966 A JP 2002-134770 A JP 2005-11923 A JP 2006-308692 A JP 2009-550092 A

  An object of the present invention is to overcome the conventional problems, and is inexpensive and has a solar cell back surface protection sheet that is excellent in scratch resistance, solvent resistance, long-term outdoor weather resistance, long-term moisture and heat resistance, and water vapor barrier properties, and the back surface of the solar cell It is providing the solar cell module which uses a protection sheet.

The present invention is a solar cell back surface protective sheet in which a weather resistant resin layer (1) having a film thickness t (μm), a plastic film (2) and an adhesive layer (3) are laminated in this order,
The weather resistant resin composition (1) in which the weather resistant resin layer (1) contains an acrylic copolymer (A), a polyester or urethane resin (B), a polyisocyanate compound (C), and a pigment (D) ( 1 '),
The acrylic copolymer (A) has a glass transition temperature of 0 to 70 ° C., a weight average molecular weight of 30,000 to 150,000, a hydroxyl value of 20 to 150 (mgKOH / g), and an aromatic ring content of maximum. 50% by weight,
The polyester or urethane resin (B) has a glass transition temperature of -30 to 20 ° C, a weight average molecular weight of 5,000 to 30,000, a hydroxyl value of 3 to 30 (mgKOH / g), and an aromatic ring content. Up to 50% by weight,
The isocyanate group in the polyisocyanate compound (B) is 0.1 to 5 times the sum of the hydroxyl groups of the acrylic copolymer (A) and the polyester or urethane resin (B). It is related with the solar cell back surface protection sheet characterized.
The ratio of the acrylic copolymer (A) to the polyester or urethane resin (B) is preferably 90/10 to 30/70 (weight ratio).

It is preferable that the acrylic copolymer (A) does not have a benzotriazole group.
The polyester-based or urethane-based resin (B) is preferably at least one selected from the group consisting of a polyester resin, a polyester urethane resin, a polycarbonate urethane resin, and a polyether urethane resin. It is preferable that the number of OH terminal functional groups contained therein is 2.1 to 5 on average.

  The pigment (D) is preferably at least one selected from the group consisting of carbon black, perylene black, titanium oxide, zinc oxide, lead oxide, zinc sulfide, and lithobon.

The weather-resistant resin composition (1 ′) further contains particles (E) having an average particle diameter of 1 μm to 1.1 × t (μm) having a melting point of 120 ° C. or higher or no melting point. The particles (E) having an average particle diameter of 1 μm to 1.1 × t (μm) are preferably nitrogen-containing resin particles.
Moreover, it is preferable that the film thickness t of a weather-resistant resin layer (1) is 5-30 micrometers.

The plastic film (3) is preferably a polyethylene terephthalate film.
Moreover, the said solar cell back surface protection sheet can have the water vapor | steam barrier layer (2) which consists of aluminum foil or a vapor deposition film between a weather resistant resin layer (1) and a plastic film (2).

The present invention provides a solar cell surface sealing sheet (I) positioned on the light receiving surface side of a solar cell, a sealing material layer (II) positioned on the light receiving surface side of the solar cell, solar cells (III), and solar cell A solar cell module comprising the sealant layer (IV) positioned on the non-light-receiving surface side and the solar cell back surface protection sheet (V) in contact with the non-light-receiving surface side sealant layer (IV) Because
The said adhesive bond layer (3) is in contact with the said non-light-receiving surface side sealing agent layer (IV), It is related with the solar cell module characterized by the above-mentioned.

  According to the present invention, a solar cell back surface protective sheet that overcomes the conventional problems, is inexpensive, has excellent scratch resistance, solvent resistance, long-term outdoor weather resistance, long-term moisture and heat resistance, and water vapor barrier properties, and the solar cell back surface protective sheet A solar cell module is provided.

It is a figure which shows typically the cross section of the module for solar cells of this invention. It is typical sectional drawing of the solar cell back surface protection sheet of this invention.

The weather resistant resin layer (1) constituting the present invention will be described.
The weather-resistant resin layer (1) in the present invention protects the inside of the solar cell back surface protection sheet, and further protects the solar cell module from external factors such as ultraviolet rays and physical impact, and suppresses the output deterioration of the solar cell. Is responsible.

The film thickness t of the weather resistant resin layer (1) is preferably 5 to 30 μm.
When the film thickness t of the weather resistant resin layer (1) is less than 5 μm, the concealability and scratch resistance are not sufficient, and when it exceeds 30 μm, it becomes difficult to form a uniform film.

The acrylic copolymer (A) used for the weather resistant resin composition (1 ′) for forming the weather resistant resin layer (1) will be described.
The acrylic copolymer (A) is used to impart toughness, weather resistance, moist heat resistance and chemical resistance to the weather resistant resin layer (1), and has a glass transition temperature of 0 to 70 ° C. and a weight average molecular weight. Of 30,000 to 150,000, a hydroxyl value of 20 to 150 (mgKOH / g), and an aromatic ring content of up to 50% by weight. The glass transition temperature here refers to the glass transition temperature measured by differential scanning calorimetry (DSC) for a resin obtained by drying the acrylic copolymer (A) to a solid content of 100%.
The acrylic resin has high weather resistance and high strength as a resin, and is therefore suitable for use in forming the weather resistant resin layer (1).

  When higher toughness, weather resistance, and heat and humidity resistance are required, a functional group capable of reacting with an isocyanate group is provided in the main chain of the acrylic copolymer (A) in order to obtain a higher crosslinking density. It is essential to introduce.

  Examples of the acrylic monomer having a functional group capable of reacting with an isocyanate group include acrylic monomers having a hydroxyl group, an amino group, a carboxyl group, an epoxy group, an N-methylol group, an N-alkoxymethyl group, and the like. An acrylic monomer having a hydroxyl group is preferred from the viewpoint of molding processability of the resulting weather resistant resin layer.

  As the (meth) acrylic monomer having a hydroxyl group, 2-hydroxyethyl (meth) acrylate, 1-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, polyethylene glycol Examples include mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and polytetramethylene glycol mono (meth) acrylate.

Other (meth) acrylic monomers include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, and the like. Aliphatic (meth) acrylates, alicyclic (meth) acrylates such as cyclohexyl methacrylate and cyclopentadienyl methacrylate, benzyl (meth) acrylate, and the like.
The (meth) acrylic monomer can be used alone or in combination of two or more depending on the required performance.

  In particular, in order to have high solvent resistance, it is very important that the hydroxyl value of the acrylic copolymer (A) is a value to be described later. Since cross-linking points can exist at a high density, the solvent is less likely to penetrate, and as a result, high solvent resistance can be achieved.

  It is important that the hydroxyl value of the acrylic copolymer (A) is 20 to 150 mgKOH / g in terms of solid content, preferably 20 to 100 mgKOH / g, and more preferably 20 to 85 mgKOH / g. When the hydroxyl value of the copolymer (A) exceeds 150 mgKOH / g, the storage stability of the copolymer (A) decreases, and when it is less than 20 mgKOH / g, sufficient crosslinking cannot be obtained. Sexuality gets worse.

  It is important that the glass transition temperature of the acrylic copolymer (A) is 0 to 70 ° C. When the glass transition temperature of the acrylic copolymer (A) exceeds 70 ° C., the adhesion of the resulting weather resistant resin layer to the base material over time of wet heat cannot be ensured, and When the temperature is lower than 0 ° C., the chemical resistance and surface hardness of the resulting weather-resistant resin layer are lowered, and tackiness is generated on the surface. The glass transition temperature here refers to the glass transition temperature measured by differential scanning calorimetry (DSC) for a resin obtained by drying the acrylic copolymer (A) to a solid content of 100%.

  It is important that the weight average molecular weight in terms of polystyrene by gel permeation chromatography (GPC) of the acrylic copolymer (A) is 30,000 to 150,000, preferably 50,000 to 140,000. is there. When the weight average molecular weight of the copolymer (a) exceeds 150,000, the extensibility of the resulting weather resistant resin layer and the adhesion to the substrate are lowered, and when it is less than 30,000, The toughness, heat-and-moisture resistance, solvent resistance, and chemical resistance of the resulting weather-resistant resin layer are lowered.

  The acrylic copolymer (A) preferably has an acid value of 0.1 mgKOH / g or less. When there is an acid value, it acts as a catalyst for promoting the decomposition of the acrylic copolymer (A), so that the heat resistance and heat-and-moisture resistance are remarkably lowered.

  The aromatic ring content in the acrylic copolymer (A) is at most 50% by weight, preferably 10% by weight or less, and preferably contains no aromatic ring as much as possible. If the content of the aromatic ring in the acrylic copolymer (A) exceeds 50% by weight, it absorbs ultraviolet rays and causes yellowing of the weather resistant resin layer (1) and deterioration of the coating film. It drops significantly.

  The acrylic copolymer (A) preferably has no benzotriazole group. The benzotriazole group plays a role of protecting the resin from ultraviolet rays by selectively converting ultraviolet rays with high solar energy into heat, but in effect, the absorbed ultraviolet rays transfer energy to the resin and degrade the resin. There is. Since the weather resistant resin layer (1) contains the pigment (D), the weather resistance resin layer (1) exhibits concealability and cuts off ultraviolet rays, so that it does not need to contain an ultraviolet absorber.

The acrylic copolymer (A) can be obtained by a known method, for example, solution polymerization. Solvents include alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol methyl ether, diethylene glycol methyl ether,
Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone,
Ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether,
Hydrocarbons such as hexane, heptane, octane,
Aromatics such as benzene, toluene, xylene, cumene,
Esters such as ethyl acetate and butyl acetate can be used.
Two or more solvents may be mixed and used.

The monomer concentration during synthesis is preferably 0 to 80% by weight.
As the polymerization initiator, a peroxide or an azo compound can be used, and examples thereof include benzoyl peroxide, azoisobutylvaleronitrile, azobisisobutyronitrile, di-t-butyl peroxide, t -Butyl perbenzoate, t-butyl peroctoate, cumene hydroxy peroxide and the like can be mentioned.
The polymerization temperature is preferably 50 to 200 ° C, particularly 70 to 140 ° C.

The polyester-based or urethane-based resin (B) used for the weather-resistant resin composition (1 ′) for forming the weather-resistant resin layer (1) will be described.
The polyester-based or urethane-based resin (B) is used for imparting toughness, molding processability, and moist heat resistance to the weather resistant resin layer (1), and has a glass transition temperature of -30 to 20 ° C and a weight average molecular weight. 5,000 to 30,000, a hydroxyl value of 3 to 30 (mgKOH / g), and an aromatic ring content of up to 50% by weight are essential.

  When the acrylic copolymer (A) of the present invention is used, a coating film having a very high crosslink density can be formed, so that high weather resistance and solvent resistance can be expressed, but on the other hand, it tends to be a hard and brittle film. . By using the acrylic copolymer (A) and the polyester or urethane resin (B) in combination for forming the weather resistant resin layer (1), the toughness is maintained while maintaining high weather resistance and solvent resistance. And moldability can be imparted, and as a result, it has high wet heat properties required for solar cell applications.

  Specific examples of the polyester-based or urethane-based resin (B) include polyester resins, polyester urethane resins, polycarbonate urethane resins, and polyether urethane resins. These can be used alone or in combination of two or more. Further, a composite of these resins can be used.

  The polyester resin is a polyester resin obtained by reacting a carboxylic acid component and a hydroxyl component (esterification reaction, transesterification reaction).

  As the carboxylic acid component constituting the polyester resin, benzoic acid, p-tert-butylbenzoic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic anhydride, adipic acid, azelaic acid, tetrehydrophthalic anhydride, hexahydrophthalic anhydride Examples thereof include acid, maleic anhydride, fumaric acid, itaconic acid, tetrachlorophthalic anhydride, 1,4-cyclohexanedicarboxylic acid, trimellitic anhydride, methylcyclocentricarboxylic anhydride, pyromellitic anhydride, ε-caprolactone, and fatty acid. .

Examples of the hydroxyl component constituting the polyester resin include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, 3-methylpentanediol, In addition to diol components such as 1,4-cyclohexanedimethanol, polyfunctional alcohols such as glycerin, trimethylolethane, trimethylolpropane, trishydroxymethylaminomethane, pentaerythritol, and dipentaerythritol can be exemplified.
According to a conventional method, those obtained by polymerizing these carboxylic acid component and hydroxyl group component into a predetermined polyester resin can be used in the present invention.

  The urethane resin is obtained by reacting a hydroxyl group component of a resin having a hydroxyl group with an isocyanate compound. If the resin having a hydroxyl group is a polyester resin, it is a polyester urethane resin, and if it is a polycarbonate resin, a polycarbonate urethane resin or a polyether is used. If it is resin, it becomes polyether urethane resin. The urethane resin also includes a polyurethane urea resin obtained by further reacting the above urethane resin with a diamine component.

  Examples of the polyester resin having a hydroxyl group of the polyester urethane resin include the above polyester resins.

  The isocyanate compound of the polyester urethane resin is not limited to the following, but is 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, 1,5-naphthalene. Examples thereof include diisocyanates such as diisocyanate, hexamethylene diisocyanate, bis (4-isocyanatocyclohexyl) methane, or hydrogenated diphenylmethane diisocyanate. As the diisocyanate (A-2), these may be used alone, or two or more kinds may be arbitrarily combined and used.

Examples of the polycarbonate resin containing a hydroxyl group of the polycarbonate urethane resin include 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, 1,9-nonanediol, and 2-methyl- And polycarbonate polyols based on one or more diols such as 1,8-octanediol. Commercially available products include, for example, Ube Industries' Etanacol UH-100, UH-200, UH-300, UHC50-200, UHC50-100, or UC-100, Kuraray Kuraray Polyol C-2090, C-2090R, Alternatively, C-3090, Placel CD210, CD210PL, CD220, CD220PL manufactured by Daicel, or polycarbonate diol T6002, T6001, T5651, T5650J, T4671, T4672, T4692, or T4691 manufactured by Asahi Kasei Co., Ltd. Isocyanate compound of polycarbonate urethane resin As, the same thing as the isocyanate compound of a polyester urethane resin can be used.

  Examples of the polyether resin containing a hydroxyl group of the polyether urethane resin include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyether polyol added with ethylene oxide and propylene oxide, and the like.

  As an isocyanate compound of polyether urethane resin, the thing similar to the isocyanate compound of polyester urethane resin can be used.

  When obtaining said polyester urethane resin, polycarbonate urethane resin, and polyether urethane resin, in order to adjust a glass transition temperature, you may use together dihydric alcohol. Two or more kinds of these dihydric alcohols can be used in any combination. For example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,9-nonanediol Or 3-methyl-1,5-pentanediol and the like.

  In addition, as the polyester-based or urethane-based resin (B), an olefin-based polyol polymer polyol such as acrylic polyol or polybutadiene-based polyol and an isocyanate compound can be used.

The polyester-based or urethane-based resin (B) is preferably a branched polyester resin, polyester urethane resin, polycarbonate urethane resin, or polyether urethane resin.
When the polyester-based or urethane copolymer (B) has a branch, the weather-resistant resin layer (1) has a higher density of cross-linking, and the weather-resistant resin layer (1) has a higher resistance to resistance. Solvent properties can be imparted.
Specifically, the number of OH terminal functional groups in one molecule of the polyester-based or urethane-based resin (B) is preferably 2.1-5. When the number of OH terminal functional groups is 5 or more, there is a high possibility of gelation during the resin synthesis reaction or during coating.

  In order to give a branch to the polyester-based or urethane-based resin (B), a polyfunctional polyol having three or more hydroxyl groups in addition to the diol component may be used as the hydroxyl component, or three or more in addition to the diisocyanate component. A polyfunctional polyisocyanate having an isocyanate group may be used.

  There are 3 multifunctional polyols such as glycerin, trimethylolpropane, 1,2,4-butanetriol, 1,2,3-propanetriol, 1,2,5-pentanetriol, hexanetriol, pentaerythritol, sorbitol The polyol which has the above hydroxyl group is mentioned.

Multifunctional polyisocyanates include diisocyanate multimers (trimers, pentamers, and 7-mers) and allophanate-modified products (such as allophanate-modified products produced by the reaction of diisocyanates with monools or polyhydric alcohols). , Biuret-modified products (such as biuret-modified products produced by reaction of diisocyanate and water), polyol-modified products (polyol modified product produced by reaction of diisocyanate and polyhydric alcohol, etc.), etc. It may be used in combination, or two or more may be used in any combination.
As diisocyanate used for formation of polyfunctional polyisocyanate, the thing similar to what was illustrated as an isocyanate compound of a polyester urethane resin can be illustrated.

The polyisocyanate compound (C) used for the weather resistant resin composition (1 ′) for forming the weather resistant resin layer (1) will be described.
The polyisocyanate compound (C) crosslinks the acrylic copolymer (A), polyester-based or urethane-based resin (B) to each other, and is tough and stretchable, flexible, moldability, scratch resistance, long-term It is used to form a weather resistant resin layer having weather resistance, long-term wet heat resistance, and chemical resistance.
In order to prevent the resulting weather-resistant resin layer from changing from yellow to brown over time, it is preferable to use only an alicyclic or aliphatic compound.

  Examples of the alicyclic polyisocyanate compound include isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated 4,4′-diphenylmethane diisocyanate, and the like.

  Examples of the aliphatic polyisocyanate compound include trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate.

  Examples of the aromatic polyisocyanate compound include diphenylmethane diisocyanate, toluylene diisocyanate, naphthylene-1,5-diisocyanate, o-xylene diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl. An isocyanate etc. are mentioned.

As the polyisocyanate compound, a double-ended isocyanate adduct, biuret-modified, or isocyanurate-modified, which is a reaction product of the above-mentioned compound and glycols or diamines, may be used.
In particular, when the polyisocyanate compound (C) contains an isocyanurate-modified product, particularly an isocyanurate ring-containing triisocyanate, it is preferable because a weather-resistant resin layer having toughness and extensibility can be obtained. Specific examples of the isocyanurate ring-containing triisocyanate include isocyanurate-modified isophorone diisocyanate (for example, Desmodur Z4470 manufactured by Sumitomo Bayer Urethane Co., Ltd.), isocyanurate-modified hexamethylene diisocyanate (for example, Sumidur manufactured by Sumitomo Bayer Urethane Co., Ltd.) N3300), isocyanurate-modified toluylene diisocyanate (for example, Sumidur FL-2, FL-3, FL-4, HL BA manufactured by Sumitomo Bayer Urethane Co., Ltd.). In addition, the isocyanate group in one molecule may be increased by reacting with a polyester (c) having two or more functional groups capable of further reacting the isocyanurate ring, or the generated urethane bond and one equivalent of isocyanate. A group may be reacted to form allophanate to further increase the isocyanate group in one molecule. As the polyester (c) having two or more functional groups capable of reacting with an isocyanate group, a known polyester resin can be used.

  The isocyanate group of the polyisocyanate compound is, for example, methanol, ethanol, n-pentanol, ethylene chlorohydrin, isopropyl alcohol, phenol, p-nitrophenol, m-cresol, acetylacetone, ethyl acetoacetate, or ε-caprolactam. You may use the block modified body which made it react with blocking agents, such as, and was made into a block.

  Furthermore, as the polyisocyanate compound (C), a polyester (d) having two or more functional groups capable of reacting with an isocyanate group and a diisocyanate compound (e) having an isocyanate group at both ends are reacted. An isocyanate prepolymer may be used. When the polyisocyanate compound (C) contains the above-mentioned both-end isocyanate prepolymer, extensibility is obtained in a small amount, and the toughness of the coating film is not impaired.

  A polyisocyanate compound (C) can be used 1 type or in combination of 2 or more types.

As the polyester (d) having two or more functional groups capable of reacting with an isocyanate group, a known polyester resin can be used.
Examples of the diisocyanate compound (e) having an isocyanate group at both ends include, for example, toluylene diisocyanate, naphthylene-1,5-diisocyanate, o-toluylene diisocyanate, diphenylmethane diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4 ′. -Diphenylmethane diisocyanate, hexamethylene diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, lysine diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate and the like.

  The polyisocyanate compound (C) comprises the acrylic copolymer (A) and the polyester-based or urethane-based resin (B) and the polyester-based or urethane-based resin (B). ) The number of isocyanate groups of the polyisocyanate compound (C) is preferably 0.1 to 5 times, more preferably 1 to 3 times the total number of functional groups capable of reacting with the isocyanate groups. If it is less than 0.1 times, the crosslinking density is too low, and the solvent resistance, scratch resistance and weather resistance are not sufficient, and if it is more than 5 times, the isocyanate is left and reacts with moisture in the air. This is a factor that changes physical properties depending on the season.

The pigment (D) used for the weather resistant resin composition (1 ′) for forming the weather resistant resin layer (1) will be described.
The weather resistant resin layer (I) contains the pigment (D) and is used to form a weather resistant resin layer having design and concealing properties. Moreover, it has a role which protects the inside of a solar cell back surface protection sheet by cutting an ultraviolet-ray.
Conventionally known pigments can be used as the pigment, but black or white is preferred from the viewpoint of design. From the viewpoint of colorability, the black pigment is preferably carbon black, and the white pigment is preferably titanium oxide, zinc oxide, lead oxide, zinc sulfide, or lithobon.

  The weather resistant resin layer (1) further contains particles (E) having an average particle diameter of 1 μm to 1.1 × t (μm) having a melting point of 120 ° C. or higher or no melting point. Is preferred. By containing such particles, the unevenness of the surface of the weather resistant resin layer (1) is increased, and the slipperiness and blocking property of the surface are improved.

As the particles (E), those having a melting point of 120 ° C. or higher or having no melting point are used.
The solar cell module includes a solar cell surface sealing sheet (I), a learning surface side sealing material (II), a solar battery cell (III), a non-learning surface side sealing material (IV), and a solar cell back surface protection sheet (V). ) Are brought into contact in this order under heating and reduced pressure and bonded together (hereinafter also referred to as this vacuum lamination). The temperature at the time of vacuum laminating is usually about 120 to 160 ° C. in terms of the softening temperature and the crosslinking temperature of the attending surface side sealing material (II) and the non-learning surface side sealing material (IV).
If particles having a melting point of less than 120 ° C. are used, the particles melt due to the heat during vacuum lamination when the solar cell module is created, so that the scratch resistance of the weather resistant resin layer (1) may be reduced, It may reduce the adhesion to. Therefore, the weather resistant resin layer (1) has a melting point of 120 ° C. or higher or does not have a melting point.

  Moreover, the average particle diameter of particle | grains (E) is 1 micrometer-1.1xt (micrometer), and it is preferable that they are 3 micrometer-1.0xt (micrometer). If the average particle diameter is less than 1 μm, the surface condition of the weather resistant resin layer (1) cannot be modified because it is too small, and the average particle diameter exceeds 1.1 × t (μm), that is, weather resistance. If the film thickness of the resin layer (1) is greatly exceeded, the concealability is lowered, which causes a decrease in weather resistance.

  The particles (E) may be inorganic fine particles or organic fine particles as long as the melting point and the average particle diameter are the above-mentioned conditions.

  Specific examples of inorganic fine particles include silica, glass fiber, glass powder, glass beads, clay, wollastonite, iron oxide, antimony oxide, lithopone, pumice powder, aluminum sulfate, zirconium silicate, dolomite, iron sand and the like Particles.

  Moreover, the said inorganic type particle | grain may contain the impurity to such an extent that the characteristic is not impaired. Further, the shape of the particles may be any shape such as powder, granule, granule, true sphere, flat plate, and fiber.

Specific examples of the organic fine particles include polyolefin wax, polymethyl methacrylate resin, polystyrene resin, nylon resin, melamine resin, guanamine resin, phenol resin, urea resin, silicon resin, methacrylate resin, acrylate resin and other polymer particles, Alternatively, cellulose powder, nitrocellulose powder, wood powder, waste paper powder, rice husk powder, starch and the like can be mentioned.
From the viewpoint of heat resistance, nitrogen-containing resin particles such as melamine resin, guanamine resin, and urea resin are preferable.

  The organic fine particles can be obtained by a polymerization method such as an emulsion polymerization method, a suspension polymerization method, a dispersion polymerization method, a soap-free polymerization method, a seed polymerization method, or a microsuspension polymerization method. The organic particles may contain impurities to the extent that the characteristics are not impaired. The shape of the particles may be any shape such as powder, granule, granule, flat plate, and fiber.

In addition, in the weather resistant resin layer (1), various thermoplastic resins other than the acrylic copolymer (A) are used in order to increase the strength of the obtained weather resistant resin layer, as long as the effects of the present invention are not hindered. May be included.
Examples of the thermoplastic resin include polypropylene, polyethylene, ethylene-vinyl acetate copolymer, polyisobutylene, polybutadiene, polystyrene, polycarbonate, polymethylpentene, ionomer, acrylonitrile-butadiene-styrene resin, acrylic resin, polyvinyl alcohol, and polyamide. Resins, polyacetals, epoxy resins and the like can be mentioned.

  The amount of the thermoplastic resin added is preferably 50 parts by weight or less, more preferably 30 parts by weight or less, based on 100 parts by weight of the total amount of the acrylic copolymer (A). If it exceeds 50 parts by weight, the compatibility with other components may decrease.

The weather resistant resin composition (1 ′) used in the present invention contains a solvent.
As the solvent, alcohols such as methanol, ethanol, propanol, butanol, ethylene glycol methyl ether, diethylene glycol methyl ether,
Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone,
Ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether,
Hydrocarbons such as hexane, heptane, octane,
Aromatics such as benzene, toluene, xylene, cumene,
Among esters such as ethyl acetate and butyl acetate, an appropriate one is used according to the composition of the resin composition. Two or more solvents may be used.

  Moreover, you may add a crosslinking accelerator to a weather resistant resin composition (1 ') as needed in the range which does not prevent the effect by this invention. The crosslinking accelerator plays a role as a catalyst for accelerating the urethane bonding reaction by the isocyanate group of the polyisocyanate compound (B) and the functional group capable of reacting with the isocyanate group of the acrylic copolymer (A). Examples of the crosslinking accelerator include tin compounds, acids and bases.

  In addition, the weather resistant resin composition (1 ′) may include a filler, a thixotropy imparting agent, an anti-aging agent, an antioxidant, an antistatic agent, a flame retardant as long as the effects of the present invention are not hindered. , Thermal conductivity improvers, plasticizers, anti-sagging agents, antifouling agents, antiseptics, bactericides, antifoaming agents, leveling agents, curing agents, thickeners, pigment dispersants, silane coupling agents, etc. Additives may be added.

  The weather-resistant resin composition (1 ′) used in the present invention is prepared by adding, for example, a polyisocyanate compound (B) and other resins to a solution of the acrylic copolymer (A) and the polyester or urethane resin (B). The components may be mixed and stirred with a stirring blade, a shaker, a rotary stirrer, or the like. Moreover, you may mix using a sand mill, 3 rolls, 2 rolls, etc. In order to improve coatability, a solvent may be added or concentrated.

The pigments (C) and particles (D) were first prepared as pastes (C) to (D) in which (C) to (D), a dispersion resin, and optionally a dispersant and a solvent were mixed. Later, it is preferable to mix with other components.
As the dispersion resin, it is preferable to use an acrylic copolymer (A) or a polyester or urethane resin (B) itself, but there is no particular limitation, and a polar group excellent in pigment dispersibility, such as a hydroxyl group or a carboxyl group. An acrylic resin, a polyurethane resin, a polyurea resin, a polyester resin, or the like having a thiol group, an amino group, an amide group, a ketone group, or the like can be used.
Examples of the dispersant include pigment derivatives, anionic surfactants, amphoteric surfactants, nonionic surfactants, titanium coupling agents, and silane coupling agents. In addition, the pigment surface can be modified by metal chelate, resin coating, or the like.

<Solar cell backside protection sheet>
The solar cell back surface protective sheet of the present invention comprises a weather resistant resin layer (1) formed from the weather resistant resin composition (1 ′), a plastic film (2) and an adhesive layer (3), and is weather resistant. The resin layer (1), the plastic film (2), and the adhesive layer (3) are laminated in this order.

Next, the plastic film (2) used in the present invention will be described.
Examples of the plastic film (2) used in the present invention include polyester resin films such as polyethylene terephthalate, polybutylene terephthalate, and polynaphthalene terephthalate, olefin films such as polyethylene, polypropylene, and polycyclopentadiene, polyvinyl fluoride, and polyvinylidene fluoride. Fluorine films such as films, polytetrafluoroethylene films, and ethylene-tetrafluoroethylene copolymer films, acrylic films, and triacetyl cellulose films can be used. From the viewpoint of film rigidity and cost, a polyester resin film is preferable, and a polyethylene terephthalate film is preferable.
Further, these films may have a single layer or a multilayer structure of two or more layers.

  These plastic film substrates (2) may be colorless or may contain coloring components such as pigments or dyes. Examples of the method of containing the coloring component include a method of kneading the coloring component in advance at the time of film formation, a method of printing the coloring component on a colorless transparent film substrate, and the like. Further, a colored film and a colorless transparent film may be bonded together.

Next, the adhesive layer (3) used in the present invention will be described.
The adhesive layer (3) in the present invention is a resin layer provided in order to improve the adhesion between the plastic film (3) and the non-light-receiving surface side sealing material (IV).
And when forming a solar cell module, non-light-receiving surface side sealing material (IV) and the solar cell back surface protection sheet (V) of this invention are stuck so that an adhesive bond layer (3) may contact | connect. Thereby, a solar cell back surface protection sheet is attached to the solar cell module.

  The adhesive layer (3) used in the present invention may be anything as long as it is generally used as an adhesive. Specific examples include polyester resins, urethane resins, and acrylic resins, and these can be used alone or in combination of two or more. Further, a composite of these resins can be used.

  Polyester resins are polyester resins obtained by reacting a carboxylic acid component and a hydroxyl component (esterification reaction, transesterification reaction), a polyester resin having a hydroxyl group, and a polyester polyurethane resin obtained by further reacting with an isocyanate compound, It also includes a polyester polyurethane polyurea resin obtained by reacting a diamine component.

  The carboxylic acid component constituting the polyester resin includes benzoic acid, p-tert-butylbenzoic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic anhydride, adipic acid, azelaic acid, tetrehydrophthalic anhydride, hexahydro anhydride Examples include phthalic acid, maleic anhydride, fumaric acid, itaconic acid, tetrachlorophthalic anhydride, 1,4-cyclohexanedicarboxylic acid, trimellitic anhydride, methylcyclocentricarboxylic anhydride, pyromellitic anhydride, ε-caprolactone, fatty acid it can.

Examples of the hydroxyl group component constituting the polyester resin include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, and 3-methylpentanediol. In addition to diol components such as 1,4-cyclohexanedimethanol, polyfunctional alcohols such as glycerin, trimethylolethane, trimethylolpropane, trishydroxymethylaminomethane, pentaerythritol and dipentaerythritol can be exemplified.
According to a conventional method, those obtained by polymerizing these carboxylic acid component and hydroxyl group component into a predetermined polyester resin can be used in the present invention.

The urethane-based resin is obtained by reacting a hydroxyl group component other than a polyester resin having a hydroxyl group with an isocyanate compound.
Examples of the hydroxyl component include polyethylene glycol, polypropylene glycol, polymer polyols such as polyether polyols added with ethylene oxide or propylene oxide, acrylic polyols, and polybutadiene polyols.

  As an isocyanate compound, the thing similar to the polyisocyanate compound (C) mentioned later can be illustrated. Trimethylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), methylene bis (4,1-phenylene) = diisocyanate (MDI), 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), xylylene diisocyanate ( XDI), trimethylolpropane adducts of these diisocyanates, isocyanurates that are trimers of these diisocyanates, burette conjugates of these diisocyanates, polymeric diisocyanates, and the like.

As a monomer constituting the acrylic resin, the general formula (a) CH ₂ = CR ₁ —CO—OR ₂ (R ₁ is a hydrogen atom or a methyl group, R ₂ is a hydroxyl group or a substituent having 1 to 20 carbon atoms). Acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-hexyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 4-hydroxybutyl acrylate, Examples include hydroxypropyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl methacrylate, hydroxypropyl methacrylate, etc. it can. Furthermore, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, N-methylol acrylamide, N-alkylol acrylamide, diacetone acrylamide, diacetone methacrylamide, acrolein, methacrolein, glycidyl methacrylate and the like can be exemplified as reactive monomers. Those obtained by copolymerizing these monomers according to a conventional method to obtain a predetermined acrylic resin can be used in the present invention.

  In order to improve the toughness, stretchability, heat resistance, moist heat resistance and weather resistance of the adhesive layer (3), it is preferable to add a crosslinking agent. For this reason, the polyester resins, urethane resins and acrylics exemplified above are preferred. The resin preferably has a reaction point such as a hydroxyl group, a carboxyl group, a sulfonyl group, a phosphonyl group, an isocyanate group, or an epoxy group.

  Examples of the crosslinking agent include polyisocyanate compounds, polyglycidyl compounds, and polyaziridyl compounds.

From the viewpoint of durability and coating liquid stability, an isocyanate compound is preferred as the curing agent having a functional group capable of reacting with a polyester-based or urethane-based resin having a hydroxyl group and an isocyanate hydroxyl group. Furthermore, a polyisocyanate compound is preferable from the viewpoint of improving durability. A blocked polyisocyanate compound may also be used.
As a polyisocyanate compound, the thing similar to what was illustrated by the polyisocyanate compound (C) can be used.

  As the curing agent, in addition to the above polyisocyanate compound, well-known oxazoline compounds such as 2,5-dimethyl-2-oxazoline, 2,2- (1,4-butylene) -bis (2-oxazoline) or hydrazide Compounds such as isophthalic acid dihydrazide, sebacic acid dihydrazide, adipic acid dihydrazide can be included.

  It is preferable that a solar cell back surface protection sheet comprises a water vapor | steam barrier layer (4). Examples of the water vapor barrier layer include a metal foil or a vapor deposition layer of a metal oxide or a non-metal inorganic oxide.

As the metal foil, aluminum foil, iron foil, zinc plywood and the like can be used. Among these, aluminum foil is preferable from the viewpoint of corrosion resistance, and the thickness is preferably 10 μm to 100 μm, and more preferably. Is preferably 20 μm to 50 μm.
Conventionally known various adhesives can be used for the lamination of the two.

  The vapor deposition layer is provided on one surface of the plastic film (2). What laminated | stacked single-sided vapor deposition polyester films via the adhesive bond layer, or what laminated | stacked single-side vapor deposition polyester film and another vapor deposition film via an adhesive bond layer can also be used.

Examples of the metal oxide or non-metal inorganic oxide to be deposited include oxides such as silicon, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, and yttrium. Alkali metal and alkaline earth metal fluorides can also be used, and these can be used alone or in combination.
These metal oxides or non-metal inorganic oxides can be deposited using a conventionally known PVD method such as vacuum deposition, ion plating, sputtering, or the like, or a CVD method such as plasma CVD or microwave CVD.

  The water vapor barrier layer (4) may be a laminate in which two or more of the above barrier layers are laminated in accordance with required electrical insulation properties and water vapor barrier properties.

  As a method of providing the weather resistant resin layer (1) or the adhesive layer (3) on the plastic film (2) or the water vapor barrier layer (4), a roll knife coater, a die coater, a roll coater, a bar coater, a gravure roll coater , Reverse roll coater, dipping, blade coater, gravure coater, micro gravure coater, comma coater, etc., and a method of coating the weather resistant resin composition (1 ′) or the adhesive composition (3 ′) by a conventionally known coating method Alternatively, a film formed from the weather-resistant resin composition (1 ′) or the adhesive composition (3 ′) can be formed from a plastic film (2) or a conventional laminating method such as dry lamination, extrusion lamination, or thermal lamination. Water vapor barrier layer (4) and pasting Like how to adapt it is.

The manufacturing method of the solar cell back surface protection sheet of this invention is demonstrated.
The solar cell back surface protective sheet of the present invention comprises a weather resistant resin layer (1) formed from a weather resistant resin composition (1 ′), a plastic film (2) and an adhesive layer (3), The weather-resistant resin layer (1) constitutes one surface of the battery back surface protection sheet, and the adhesive layer (3) constitutes the other surface of the solar cell back surface protection sheet.
FIG. 2 (a) is a schematic diagram showing still another embodiment of the solar cell back surface protective sheet of the present invention, in which a weather resistant resin layer (1), a plastic film (2), and an adhesive layer (3) are laminated. It is sectional drawing.
The solar cell back surface protective sheet of the present invention can further include a water vapor barrier layer (4), an interlayer adhesive layer (5), and the like.
For example, FIG. 2 (b) is formed by laminating a weather resistant resin layer (1), a water vapor barrier layer (4), an interlayer adhesive layer (5), a plastic film (2), and an adhesive layer (3). It is typical sectional drawing which shows another aspect of the solar cell back surface protection sheet of this invention.
Moreover, FIG.2 (c) is formed by laminating a weather resistant resin layer (1), a plastic film (2), an interlayer adhesive layer (5), a water vapor barrier layer (4), and an adhesive layer (3). It is typical sectional drawing which shows another aspect of the solar cell back surface protection sheet of this invention.

Next, the manufacturing method of the solar cell module of this invention is demonstrated.
The solar cell module of the present invention includes a solar cell surface sealing sheet (I) positioned on the light receiving surface side of the solar cell, a sealing material layer (II) positioned on the light receiving surface side of the solar cell, and a solar cell element (III ), The sealing material layer (IV) positioned on the non-light-receiving surface side of the solar cell, and the solar cell back surface protective sheet of the present invention described in detail, as essential constituent layers, the non-light-receiving surface side sealing material layer ( It can obtain by laminating | stacking a solar cell back surface sealing sheet so that the adhesive bond layer (3) which comprises the solar cell back surface protection sheet of this invention may contact IV). When laminating the non-light-receiving surface side sealing material layer (IV) and the solar cell back surface protective sheet, they can be obtained by bringing them into contact under reduced pressure and then superposing them under heating and pressure. In the case where the adhesive layer (3) is thermosetting, the adhesive layer (3) can be further cured after being returned to normal pressure and then placed under a higher temperature condition.

Hereinafter, the present invention will be described in more detail with reference to examples. In the examples, “part” means “part by weight” and “%” means “% by weight”. Table 1 shows the physical properties of the acrylic copolymer solution, and Table 2 shows the physical properties of the polyester-based or urethane-based resin solution.
<Acrylic copolymer solution A1>
In a four-necked flask equipped with a condenser, a stirrer, a thermometer, and a nitrogen inlet tube, 15 parts of methyl methacrylate, 67 parts of n-butyl methacrylate, 16 parts of 2-hydroxyethyl methacrylate, pentamethylbipiperidinyl methacrylate (Hitachi) Kasei, Fancryl FA-711MM) and 100 parts of toluene were added, the temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere, 0.15 parts of azobisisobutyronitrile was added, and the polymerization reaction was carried out for 2 hours. Next, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours. Average molecular weight 32,000, weight average molecular weight 68,000, hydroxyl value 70.1 (mgKOH / g), acid value 0 (mgKOH / g , Tg was obtained for 35 ° C. of the acrylic copolymer A1 solution (50% solids).

The weight average molecular weight, glass transition temperature, acid value, and hydroxyl value were measured as described below.
<Measurement of number average molecular weight (Mn) and weight average molecular weight (Mw)>
The number average molecular weight (Mn) and the weight average molecular weight (Mw) were measured using GPC (gel permeation chromatography). GPC is liquid chromatography that separates and quantifies substances dissolved in a solvent (THF; tetrahydrofuran) based on the difference in molecular size, and the number average molecular weight (Mn) and the weight average molecular weight (Mw) are determined in terms of polystyrene.

<Measurement of glass transition temperature (Tg)>
The glass transition temperature was measured by differential scanning calorimetry (DSC).
About 10 mg of sample was weighed in an aluminum pan and set in a DSC apparatus (reference: the same type of aluminum pan without sample). After heating at 300 ° C. for 5 minutes, using liquid nitrogen − Rapid cooling was performed to 120 ° C. Thereafter, the temperature was raised at 10 ° C./min, and the glass transition temperature (Tg) was calculated from the obtained DSC chart (unit: ° C.).
In addition, the sample for Tg measurement used what heated said acrylic copolymer solution at 150 degreeC for about 15 minutes, and was made to dry.

<Measurement of acid value (AV)>
About 1 g of a sample (resin solution: about 50%) is accurately weighed in a stoppered Erlenmeyer flask, and 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution is added and dissolved. To this is added phenolphthalein reagent as an indicator and held for 30 seconds. Thereafter, the solution is titrated with a 0.1N alcoholic potassium hydroxide solution until the solution becomes light red.
The acid value was determined by the following formula. The acid value was a numerical value of the dry state of the resin (unit: mgKOH / g).
Acid value (mgKOH / g) = {(5.611 × a × F) / S} / (Nonvolatile content concentration / 100)
Where S: Amount of sample collected (g)
a: Consumption of 0.1N alcoholic potassium hydroxide solution (ml)
F: Potency of 0.1N alcoholic potassium hydroxide solution

<Measurement of hydroxyl value (OHV)>
About 1 g of a sample (resin solution: about 50%) is accurately weighed in a stoppered Erlenmeyer flask, and 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution is added and dissolved. Further, exactly 5 ml of an acetylating agent (a solution in which 25 g of acetic anhydride was dissolved in pyridine to make a volume of 100 ml) was added and stirred for about 1 hour. To this, phenolphthalein reagent is added as an indicator and lasts for 30 seconds. Thereafter, the solution is titrated with a 0.1N alcoholic potassium hydroxide solution until the solution becomes light red.
The hydroxyl value was determined by the following formula. The hydroxyl value was a numerical value in the dry state of the resin (unit: mgKOH / g).

Hydroxyl value (mgKOH / g) = [{(ba) × F × 28.25} / S] / (Nonvolatile content concentration / 100) + D
Where S: Amount of sample collected (g)
a: Consumption of 0.1N alcoholic potassium hydroxide solution (ml)
b: Consumption of 0.1N alcoholic potassium hydroxide solution in the empty experiment (ml)
F: Potency of 0.1N alcoholic potassium hydroxide solution D: Acid value (mgKOH / g)

<Solution of acrylic copolymer A2>
In a four-necked flask equipped with a condenser, a stirrer, a thermometer, and a nitrogen inlet tube, 35 parts of methyl methacrylate, 27 parts of n-butyl methacrylate, 28 parts of 2-ethylhexyl methacrylate, 8 parts of 2-hydroxyethyl methacrylate, pentamethyl Charge 2 parts of bipiperidinyl methacrylate and 100 parts of toluene, raise the temperature to 80 ° C. with stirring in a nitrogen atmosphere, add 0.15 parts of azobisisobutyronitrile and conduct a polymerization reaction for 2 hours. Then, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and the number average molecular weight was 40. , 000, weight average molecular weight 84,000, hydroxyl value 34.5 (mgKOH / g), acid value 0 (mgKOH / g), T There was obtained an acrylic copolymer A2 of 36 ° C. solution (50% solids).

<Solution of acrylic copolymer A3>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 48 parts of isobornyl methacrylate, 40 parts of n-butyl methacrylate, 10 parts of 4-hydroxybutyl acrylate, pentamethylbipiperidinyl methacrylate 2 parts and 100 parts of toluene were added, the temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere, 0.15 part of azobisisobutyronitrile was added and a polymerization reaction was carried out for 2 hours. 0.07 part of nitrile is added and the polymerization reaction is further performed for 2 hours, further 0.07 part of azobisisobutyronitrile is added and the polymerization reaction is further performed for 2 hours, the number average molecular weight is 33,000, and the weight average Acrylic copolymer A3 having a molecular weight of 65,000, a hydroxyl value of 48.3 (mgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of 50 ° C. To obtain a solution (50% solids).

<Solution of acrylic copolymer A4>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 53 parts of cyclohexyl methacrylate, 40 parts of n-butyl methacrylate, 5 parts of 4-hydroxybutyl acrylate, 2 parts of pentamethylbipiperidinyl methacrylate , 100 parts of toluene was added, the temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere, 0.12 part of azobisisobutyronitrile was added and a polymerization reaction was performed for 2 hours, and then azobisisobutyronitrile was added. 0.06 part is added and the polymerization reaction is further performed for 2 hours, and 0.06 part of azobisisobutyronitrile is further added and the polymerization reaction is further performed for 2 hours. The number average molecular weight is 44,000 and the weight average molecular weight is Acrylic copolymer A4 having 91,000, hydroxyl value of 25.2 (mgKOH / g), acid value of 0 (mgKOH / g), and Tg of 15 ° C. It was obtained from solution (50% solids).
<Solution of acrylic copolymer A5>
In a four-necked flask equipped with a condenser, stirrer, thermometer, and nitrogen inlet tube, 53 parts of methyl methacrylate, 35 parts of n-butyl acrylate, 10 parts of 4-hydroxybutyl acrylate, 2 parts of pentamethylbipiperidinyl methacrylate , 100 parts of toluene was added, the temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere, 0.12 part of azobisisobutyronitrile was added and a polymerization reaction was performed for 2 hours, and then azobisisobutyronitrile was added. 0.06 part is added and a polymerization reaction is further performed for 2 hours, and 0.06 part of azobisisobutyronitrile is further added and the polymerization reaction is further performed for 2 hours. The number average molecular weight is 54,000, and the weight average molecular weight is 105. , A hydroxyl value of 47.8 (mgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of 6 ° C. solution of acrylic copolymer A5 (solid Minute to obtain a 50%).

<Acrylic copolymer A6 solution>
In a four-necked flask equipped with a condenser, a stirrer, a thermometer, and a nitrogen inlet tube, 19 parts of methyl methacrylate, 64 parts of n-butyl methacrylate, 15 parts of 2-hydroxyethyl methacrylate, 2 parts of pentamethylbipiperidinyl methacrylate , 100 parts of toluene was added, the temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere, 0.22 part of azobisisobutyronitrile was added and a polymerization reaction was performed for 2 hours, and then azobisisobutyronitrile was added. 0.07 part is added and the polymerization reaction is further performed for 2 hours, and 0.07 part of azobisisobutyronitrile is further added and the polymerization reaction is further performed for 2 hours. The number average molecular weight is 18,000 and the weight average molecular weight is A solution of acrylic copolymer A6 having 39,000, hydroxyl value of 65.2 (mgKOH / g), acid value of 0 (mgKOH / g), and Tg of 35 ° C. Was obtained (50% solids).

<Solution of acrylic copolymer A7>
In a four-necked flask equipped with a condenser, a stirrer, a thermometer, and a nitrogen inlet tube, 53 parts of cyclohexyl methacrylate, 19 parts of n-butyl methacrylate, 20 parts of 2-ethylhexyl acrylate, 6 parts of 2-hydroxyethyl methacrylate, pentamethyl Charge 2 parts of bipiperidinyl methacrylate and 100 parts of toluene, raise the temperature to 80 ° C. with stirring in a nitrogen atmosphere, add 0.10 parts of azobisisobutyronitrile and conduct a polymerization reaction for 2 hours. Then, 0.08 parts of azobisisobutyronitrile was added and the polymerization reaction was further carried out for 2 hours, and further, 0.08 parts of azobisisobutyronitrile was added and the polymerization reaction was carried out for another 2 hours, and the number average molecular weight was 63. , A weight average molecular weight of 136,000, a hydroxyl value of 26.2 (mgKOH / g), an acid value of 0 (mgKOH / ), Tg was obtained for 32 ° C. of the acrylic copolymer A7 solution (50% solids).

<Acrylic copolymer A8 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube, 22 parts of methyl methacrylate, 46 parts of n-butyl methacrylate, 10 parts of 2-ethylhexyl methacrylate, 20 parts of 2-hydroxyethyl methacrylate, pentamethyl Charge 2 parts of bipiperidinyl methacrylate and 100 parts of toluene, raise the temperature to 80 ° C. with stirring in a nitrogen atmosphere, add 0.15 parts of azobisisobutyronitrile and conduct a polymerization reaction for 2 hours. Then, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and the number average molecular weight was 30. , 000, weight average molecular weight 65,000, hydroxyl value 80.2 (mgKOH / g), acid value 0 (mgKOH / g), g was obtained of 33 ° C. of the acrylic copolymer A8 solution (50% solids).

<Acrylic copolymer A9 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube is charged with 70 parts of methyl methacrylate, 30 parts of 4-hydroxybutyl acrylate, and 100 parts of toluene, and is stirred up to 80 ° C. in a nitrogen atmosphere The temperature was raised, 0.12 part of azobisisobutyronitrile was added and the polymerization reaction was carried out for 2 hours, then 0.06 part of azobisisobutyronitrile was added and the polymerization reaction was carried out for another 2 hours. 0.06 part of azobisisobutyronitrile was added, and the polymerization reaction was further carried out for 2 hours. The number average molecular weight was 45,000, the weight average molecular weight was 94,000, the hydroxyl value was 115.2 (mgKOH / g), the acid A solution (solid content 50%) of an acrylic copolymer solution A9 having a value of 0 (mgKOH / g) and Tg of 21 ° C. was obtained.

<Acrylic copolymer A10 solution>
In a four-necked flask equipped with a condenser, a stirrer, a thermometer, and a nitrogen inlet tube, 43 parts of methyl methacrylate, 52 parts of n-butyl acrylate, 3 parts of 4-hydroxybutyl acrylate, 2 parts of pentamethylbipiperidinyl methacrylate , 100 parts of toluene was added, the temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere, 0.15 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours, and then azobisisobutyronitrile was added. 0.07 part is added and the polymerization reaction is further performed for 2 hours, and 0.07 part of azobisisobutyronitrile is further added and the polymerization reaction is further performed for 2 hours. The number average molecular weight is 42,000 and the weight average molecular weight is A solution of an acrylic copolymer A10 having a solid value of 86,000, a hydroxyl value of 13.8 (mgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of 7 ° C. Minute to obtain a 50%).
<Acrylic copolymer A11 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 40 parts of methyl methacrylate, 28 parts of n-butyl methacrylate, 28 parts of 2-ethylhexyl methacrylate, 2 parts of 2-hydroxyethyl methacrylate, pentamethyl Charge 2 parts of bipiperidinyl methacrylate and 100 parts of toluene, raise the temperature to 80 ° C. with stirring in a nitrogen atmosphere, add 0.15 parts of azobisisobutyronitrile and conduct a polymerization reaction for 2 hours. Then, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and the number average molecular weight was 35. , 3,000, weight average molecular weight 73,000, hydroxyl value 9.4 (mg KOH / g), acid value 0 (mg KOH / g), Tg It was obtained in 37 ° C. solution of an acrylic copolymer A11 (solid content: 50%).

<Acrylic copolymer A12 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube, 35 parts of isobornyl methacrylate, 59 parts of n-butyl methacrylate, 4 parts of 4-hydroxybutyl acrylate, pentamethylbipiperidinyl methacrylate 2 parts and 100 parts of toluene were added, the temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere, 0.15 part of azobisisobutyronitrile was added and a polymerization reaction was carried out for 2 hours. 0.07 part of nitrile is added and the polymerization reaction is further performed for 2 hours, further 0.07 part of azobisisobutyronitrile is added and the polymerization reaction is further performed for 2 hours, the number average molecular weight is 32,000, and the weight average Acrylic copolymer A12 having a molecular weight of 67,000, a hydroxyl value of 17.5 (mgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of 45 ° C. To obtain a solution (50% solids).

<Acrylic copolymer A13 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 62 parts of methyl methacrylate, 26 parts of n-butyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 2 parts of pentamethylbipiperidinyl methacrylate , 100 parts of toluene was added, the temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere, 0.15 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours, and then azobisisobutyronitrile was added. 0.07 part is added and the polymerization reaction is further performed for 2 hours, and 0.07 part of azobisisobutyronitrile is further added and the polymerization reaction is further performed for 2 hours. The number average molecular weight is 40,000 and the weight average molecular weight is Acrylic copolymer solution A1 having 79,000, hydroxyl value of 41.5 (mgKOH / g), acid value of 0 (mgKOH / g), and Tg of 73 ° C. It was obtained.

<Acrylic copolymer solution A14>
In a four-necked flask equipped with a condenser, stirrer, thermometer, and nitrogen inlet tube, 80 parts of methyl methacrylate, 8 parts of n-butyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 2 parts of pentamethylbipiperidinyl methacrylate , 100 parts of toluene was added, the temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere, 0.15 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours, and then azobisisobutyronitrile was added. 0.07 part is added and the polymerization reaction is further performed for 2 hours, and 0.07 part of azobisisobutyronitrile is further added and the polymerization reaction is further performed for 2 hours. The number average molecular weight is 43,000 and the weight average molecular weight is Acrylic copolymer with 87,000, hydroxyl value of 40.6 (mgKOH / g), acid value of 0 (mgKOH / g), Tg of 89 ° C. and solid content of 50% To obtain a solution of the body A14 (50% solids).

<Solution of acrylic copolymer A15>
In a four-necked flask equipped with a condenser, stirrer, thermometer, and nitrogen inlet tube, 32 parts of methyl methacrylate, 32 parts of n-butyl acrylate, 26 parts of 2-ethylhexyl methacrylate, 8 parts of 4-hydroxybutyl acrylate, pentamethyl Charge 2 parts of bipiperidinyl methacrylate and 100 parts of toluene, raise the temperature to 80 ° C. with stirring in a nitrogen atmosphere, add 0.15 parts of azobisisobutyronitrile and conduct a polymerization reaction for 2 hours. Then, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and the number average molecular weight was 35. , 000, weight average molecular weight 70,000, hydroxyl value 38.8 (mgKOH / g), acid value 0 (mgKOH / g), Tg 5 ° C. a solution of the acrylic copolymer A15 (solid content 50%) was obtained.

<Acrylic copolymer A16 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube, 30 parts of methyl methacrylate, 30 parts of n-butyl acrylate, 30 parts of 2-ethylhexyl methacrylate, 8 parts of 2-hydroxyethyl methacrylate, pentamethyl Charge 2 parts of bipiperidinyl methacrylate and 100 parts of toluene, raise the temperature to 80 ° C. with stirring in a nitrogen atmosphere, add 0.15 parts of azobisisobutyronitrile and conduct a polymerization reaction for 2 hours. Then, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and further, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further performed for 2 hours, and the number average molecular weight was 40. , 1,000, weight average molecular weight 81,000, hydroxyl value 34.6 (mgKOH / g), acid value 0 (mgKOH / g), Tg Yield of -20 ° C. of the acrylic copolymer A16 solution (50% solids).

<Acrylic copolymer A17 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 40 parts of methyl methacrylate, 30 parts of n-butyl methacrylate, 20 parts of 2-ethylhexyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 100 of toluene The temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere, 0.45 part of azobisisobutyronitrile was added, and the polymerization reaction was carried out for 2 hours. 07 parts are added and the polymerization reaction is further performed for 2 hours, and 0.07 parts of azobisisobutyronitrile is further added and the polymerization reaction is further performed for 2 hours. The number average molecular weight is 10,000, and the weight average molecular weight is 21,000. A solution of an acrylic copolymer A17 having a hydroxyl value of 33.9 (mgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of 24 ° C. ( To obtain a solid content of 50%).

<Acrylic copolymer A18 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 40 parts of methyl methacrylate, 30 parts of n-butyl methacrylate, 20 parts of 2-ethylhexyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, 100 of toluene The temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere, 0.08 part of azobisisobutyronitrile was added, and the polymerization reaction was carried out for 2 hours. 07 parts are added and the polymerization reaction is further performed for 2 hours, and 0.07 parts of azobisisobutyronitrile is further added and the polymerization reaction is further performed for 2 hours. The number average molecular weight is 75,000 and the weight average molecular weight is 165,000. A solution of an acrylic copolymer A18 having a hydroxyl value of 33.5 (mgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of 24 ° C. 50% solids) was obtained.

<Acrylic copolymer A19 solution>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube is charged with 22 parts of methyl methacrylate, 77.5 parts of n-butyl methacrylate, 0.5 part of 4-hydroxybutyl acrylate, and 100 parts of toluene. The temperature was raised to 80 ° C. with stirring in a nitrogen atmosphere, 0.15 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours, and then 0.07 part of azobisisobutyronitrile was added. The polymerization reaction is further carried out for 2 hours, 0.07 parts of azobisisobutyronitrile is further added, and the polymerization reaction is further carried out for 2 hours. The number average molecular weight is 35,000, the weight average molecular weight is 73,000, the hydroxyl value is Was 1.9 (mgKOH / g), the acid value was 0 (mgKOH / g), and the Tg was 35 ° C. A solution of acrylic copolymer A19 (solid content 50%) was obtained.

<Solution of acrylic copolymer A20>
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube was charged with 50 parts of n-butyl methacrylate, 50 parts of 2-hydroxyethyl methacrylate, and 100 parts of toluene, and stirred while stirring in a nitrogen atmosphere. The temperature was raised to 0 ° C., 0.15 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours, then 0.07 part of azobisisobutyronitrile was added to conduct a polymerization reaction for another 2 hours, Further, 0.07 part of azobisisobutyronitrile was added and the polymerization reaction was further carried out for 2 hours. The number average molecular weight was 28,000, the weight average molecular weight was 54,000, and the hydroxyl value was 193.1 (mgKOH / g). An acrylic copolymer A20 solution (solid content 50%) having an acid value of 0 (mg KOH / g) and a Tg of 35 ° C. was obtained.

<Acrylic copolymer A21 solution>
In a four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube, 55 parts of styrene, 35 parts of 2-ethylhexyl methacrylate, 10 parts of 2-hydroxyethyl methacrylate, and 100 parts of toluene were charged, and under a nitrogen atmosphere While stirring, the temperature was raised to 80 ° C., 0.15 part of azobisisobutyronitrile was added to conduct a polymerization reaction for 2 hours, and then 0.07 part of azobisisobutyronitrile was added to conduct polymerization for another 2 hours. Then, 0.07 part of azobisisobutyronitrile was added and polymerization reaction was further performed for 2 hours. The number average molecular weight was 22,000, the weight average molecular weight was 48,000, and the hydroxyl value was 39.9 ( mgKOH / g), an acid value of 0 (mgKOH / g), Tg of 13 ° C., and a solution of acrylic copolymer A21 having a solid content of 50% (solid content of 50%) were obtained.

<Solution of polyester resin B1>
40 parts butylethylpropanediol, 40 parts cyclohexanedimethanol, 20 parts trimethylolpropane, 33 parts adipic acid, 4-methylhexahydrophthalic anhydride and hexahydrophthalic anhydride mixture (manufactured by Shin Nippon Rika Co., Ltd., Ricacid MH- 700) 67 parts were charged into a reaction can and gradually heated to 140 to 160 ° C. with stirring under a nitrogen stream to carry out an esterification reaction. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 5,500, the weight average molecular weight was 12,000, and the hydroxyl value was 13.5. A solution (solid content 50%) of polyester-based resin B1 (mgKOH / g), acid value 0 (mgKOH / g), and Tg 6 ° C. was obtained.

<Solution of polyester resin B2>
40 parts of butylethylpropanediol, 40 parts of cyclohexanedimethanol, 20 parts of trimethylolpropane, 67 parts of adipic acid, 4-methylhexahydrophthalic anhydride and xahydrophthalic anhydride mixture (manufactured by Shin Nippon Rika Co., Ltd., Ricacid MH- 700) 33 parts were charged into a reaction can and gradually heated to 140 to 160 ° C. with stirring under a nitrogen stream to carry out an esterification reaction. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 6,700, the weight average molecular weight was 22,000, and the hydroxyl value was 6.9. (MgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of −14 ° C. polyester resin B2 solution (solid content 50%) was obtained.

<Solution of urethane-based resin B3>
80 parts of polycarbonate diol (manufactured by Kuraray Co., Ltd., C-590, number average molecular weight 500), 20 parts of trimethylolpropane, and 82 parts of isophorone diisocyanate are charged into a reaction can and gradually heated to 140 to 160 ° C. while stirring in a nitrogen stream. The urethanization reaction was carried out. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 5,500, the weight average molecular weight was 12,000, and the hydroxyl value was 14.7. (MgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of 4 ° C. urethane resin B3 solution (solid content 50%) was obtained.

<Solution of urethane resin B4>
80 parts of polycarbonate diol (manufactured by Kuraray Co., Ltd., C-590, number average molecular weight 500), 20 parts of trimethylolpropane, and 86 parts of isophorone diisocyanate are charged into a reaction can and gradually heated to 140 to 160 ° C. while stirring in a nitrogen stream. The urethanization reaction was carried out. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 5,500, the weight average molecular weight was 15,000, and the hydroxyl value was 8.9. A solution (50% solid content) of urethane-based resin B4 (mgKOH / g), acid value 0 (mgKOH / g), and Tg 8 ° C. was obtained.

<Solution of urethane resin B5>
80 parts of polycarbonate diol (manufactured by Kuraray Co., Ltd., C-590, number average molecular weight 500), 20 parts of trimethylolpropane and 90 parts of isophorone diisocyanate are charged into a reaction can and gradually heated to 140 to 160 ° C. while stirring in a nitrogen stream. The urethanization reaction was carried out. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 10,500, the weight average molecular weight was 22,000, and the hydroxyl value was 6.2 ( mgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of 11 ° C. solution of urethane resin B5 (solid content 50%) was obtained.

<Solution of urethane-based resin B6>
80 parts of polycarbonate diol (manufactured by Kuraray Co., Ltd., C-1090, number average molecular weight 1000), 20 parts of trimethylolpropane, and 76 parts of isophorone diisocyanate are charged into a reaction can and gradually heated to 140 to 160 ° C. while stirring in a nitrogen stream. The urethanization reaction was carried out. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 6,000, the weight average molecular weight was 12,000, and the hydroxyl value was 11.6. (MgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of −20 ° C. urethane resin B6 solution (solid content 50%) was obtained.

<Solution of urethane resin B7>
80 parts of polycarbonate diol (manufactured by Kuraray Co., Ltd., C-1090, number average molecular weight 1000), 20 parts of trimethylolpropane, and 86 parts of isophorone diisocyanate are charged into a reaction can and gradually heated to 140 to 160 ° C. while stirring in a nitrogen stream. The urethanization reaction was carried out. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 8,500, the weight average molecular weight was 20,000, and the hydroxyl value was 7.4. (MgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of −18 ° C. A urethane resin B7 solution (solid content 50%) was obtained.

<Solution of urethane-based resin B8>
Polycarbonate diol (manufactured by Kuraray Co., Ltd., C-1090, number average molecular weight 1000) 100 parts, isophorone diisocyanate 82 parts, 4 parts of isophorone diisocyanate nurate compound were charged into a reaction can and stirred at 140 to 160 ° C. under a nitrogen stream. Until the urethanization reaction was carried out. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 9,000, the weight average molecular weight was 23,000, and the hydroxyl value was 6.1. (MgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of −22 ° C. urethane resin B8 solution (solid content 50%) was obtained.

<Solution of urethane-based resin B9>
Polycarbonate diol (manufactured by Kuraray Co., Ltd., C-1090, number average molecular weight 1000) 100 parts, isophorone diisocyanate 77 parts, 9 parts of isophorone diisocyanate nurate compound were charged into a reaction can and stirred at 140 to 160 ° C. under a nitrogen stream. Until the urethanization reaction was carried out. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 9,000, the weight average molecular weight was 25,000, and the hydroxyl value was 5.6. (MgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of −12 ° C. in a urethane resin B9 solution (solid content 50%) was obtained.

<Solution of urethane-based resin B10>
Polycarbonate diol (manufactured by Kuraray Co., Ltd., C-590, number average molecular weight 500) 80 parts, 1,5-pentanediol 20 parts, isophorone diisocyanate 78 parts are charged into a reaction can and stirred under a nitrogen stream 140-160. The urethanization reaction was carried out by gradually heating to ° C. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 6,000, the weight average molecular weight was 10,000, and the hydroxyl value was 11.3. (MgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of −2 ° C. in a urethane resin B10 solution (solid content 50%) were obtained.

<Solution of urethane-based resin B11>
Polycarbonate diol (manufactured by Kuraray Co., Ltd., C-1090, number average molecular weight 1000) 80 parts, 1,5-pentanediol 20 parts, isophorone diisocyanate 80 parts were charged into a reaction can and stirred under a nitrogen stream while being 140- The urethanization reaction was performed by gradually heating to 160 ° C. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 8,500, the weight average molecular weight was 19,000, and the hydroxyl value was 6.1. (MgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of −19 ° C. urethane resin B11 solution (solid content 50%) was obtained.

<Solution of urethane-based resin B12>
70 parts of polycarbonate diol (Kuraray Co., Ltd., C-590, number average molecular weight 500), 30 parts of trimethylolpropane and 86 parts of isophorone diisocyanate were charged into a reaction can and stirred at 140 to 160 ° C. under a nitrogen stream. It was gradually heated to carry out a urethanization reaction. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 7,000, the weight average molecular weight was 21,000, and the hydroxyl value was 9.6. A solution (solid content 50%) of urethane-based resin solution B12 (mgKOH / g), acid value of 0 (mgKOH / g), and Tg of −17 ° C. was obtained.

<Solution of urethane-based resin B13>
80 parts of polycarbonate diol (manufactured by Kuraray Co., Ltd., C-590, number average molecular weight 500), 20 parts of trimethylolpropane, and 70 parts of isophorone diisocyanate were charged into a reaction can and stirred at 140 to 160 ° C. under a nitrogen stream. It was gradually heated to carry out a urethanization reaction. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 2,000, the weight average molecular weight was 4,000, and the hydroxyl value was 34.6. (MgKOH / g), an acid value of 0 (mgKOH / g), and a Tg of −5 ° C. urethane resin B13 solution (solid content 50%) was obtained.

<Solution of urethane-based resin B14>
80 parts of polycarbonate diol (manufactured by Kuraray Co., Ltd., C-590, number average molecular weight 500), 20 parts of trimethylolpropane, and 78 parts of isophorone diisocyanate are charged into a reaction can and stirred at 140 to 160 ° C. under a nitrogen stream. It was gradually heated to carry out a urethanization reaction. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 4,500, the weight average molecular weight was 9,000, and the hydroxyl value was 17.5. A solution (solid content 50%) of urethane-based resin B14 (mgKOH / g), acid value 0 (mgKOH / g), and Tg 0 ° C. was obtained.

<Solution of urethane-based resin B15>
80 parts of polycarbonate diol (manufactured by Kuraray Co., Ltd., C-590, number average molecular weight 500), 20 parts of trimethylolpropane, and 92 parts of isophorone diisocyanate are charged into a reaction can and stirred at 140 to 160 ° C. under a nitrogen stream. It was gradually heated to carry out a urethanization reaction. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, and the number average molecular weight was 15,000, the weight average molecular weight was 32,000, and the hydroxyl value was 4.3. A solution (solid content 50%) of urethane-based resin solution B15 (mgKOH / g), acid value 0 (mgKOH / g), and Tg 13 ° C. was obtained.

<Solution of urethane resin B16>
30 parts butylethylpropanediol, 30 parts cyclohexanedimethanol, 40 parts trimethylolpropane, 1 part isophthalic acid, 4-methylhexahydrophthalic anhydride and hexahydrophthalic anhydride mixture (manufactured by Shin Nippon Rika Co., Ltd., Ricacid MH- 700) 99 parts was charged into a reaction can and gradually heated to 140 to 160 ° C. with stirring under a nitrogen stream to carry out a urethanization reaction. After reacting at 160 ° C. for 3 hours and confirming that there is no NCO peak by IR measurement, ethyl acetate was added, the number average molecular weight was 2,500, the weight average molecular weight was 7,000, and the hydroxyl value was 20.8. A solution (50% solid content) of urethane-based resin B16 (mg KOH / g), acid value 0 (mg KOH / g), and Tg 30 ° C. was obtained.

<Solution of polyisocyanate compound C>
The hexamethylene diisocyanate trimer was diluted with ethyl acetate to obtain a polyisocyanate compound (C) solution as a resin solution having a solid content of 70%.

<Adjustment of coating solution for forming weather resistant resin layer>
Acrylic copolymer (A) solution, polyester-based or urethane-based resin (B) solution, polyisocyanate compound (C) solution, pigment (D), and particles (E) are mixed in the compositions shown in Tables 3-5. Then, coating solutions 1 to 40 for forming a weather resistant resin layer were obtained. In addition, the composition in a table | surface is solid content conversion.
In the table, each symbol is as follows.
Typeke CR-97: Ishihara Sangyo Titanium Oxide for White Pigment Poster MS: Nippon Shokubai Benzoguanamine Particles TEXTURE 5378W: SHAMROCK Crystalline Polyethylene Particles S362N1: SHAMROCK Olefin Wax

<Creation of solar cell back surface protection sheet 1>
Corona treatment was applied to both sides of a polyester film (Teijin Limited, Tetoron S, thickness 188 μm, hereinafter referred to as “transparent substrate A”), and polyester adhesive “Dyna Leo VA-3020 / HD-701” (Toyo) on one side Ink Manufacture Co., Ltd., blending ratio 100/7, the same applies hereinafter) is applied by a gravure coater, the solvent is dried, and an adhesive amount of 10 g / square meter is provided, and the following vapor deposition is applied to the adhesive layer. The vapor deposition surfaces of PET (Mitsubishi Resin Co., Ltd., Tech Barrier LX, thickness 12 micrometers) were piled up. Thereafter, an aging treatment was performed at 50 ° C. for 4 days, the adhesive layer was cured, and a polyester film-deposited PET laminate was prepared.

  Furthermore, the weather resistant resin layer forming coating solution 1 described in Table 3 was applied to the surface of the polyester film-deposited PET laminate, and the solvent was dried to provide a weather resistant resin layer having a thickness of about 15 μm. . Thereafter, aging treatment was performed at 40 ° C. for 3 days to cure the weatherable resin layer, and a weatherable resin layer-polyester film-deposited PET laminate was produced.

  Furthermore, a polyester adhesive “Dyna Leo VA-3020 / HD-701” (manufactured by Toyo Ink Co., Ltd., blending ratio 100/7, hereinafter the same) on the vapor-deposited PET surface of the weather-resistant resin layer-polyester film-deposited PET laminate Was applied with a gravure coater, the solvent was dried, an adhesive amount of 4 g / square meter was provided, and a solar cell back surface protective sheet 1 was prepared.

<Creation of solar cell back surface protection sheets 2-40>
In the same manner as in the solar cell back surface protective sheet 1, a solar cell back surface protective sheet 2-40 was prepared using the coating solution 2-40 for forming a weather resistant resin layer shown in Tables 3 to 5.

<Creation of solar cell back surface protection sheet 41>
The solar cell back surface protective sheet 41 having a layer structure of polyester film-deposited PET-adhesive layer without providing a weather resistant resin layer was prepared by the same production method as the solar cell back surface protective sheet 1.

[Example 1]
Evaluation of cross-cut adhesion, scratch resistance, heat resistance, solvent resistance, moist heat resistance, and weather resistance of the weather resistant resin layer to the plastic film (2) using the solar cell back surface protective sheet 1 by the method described later. went.

<Cross-cut adhesion measurement>
For cross-cut adhesion, the weather-resistant resin layer of the solar cell back surface protective sheet 1 is scratched in a cross shape with a cutter, subjected to a cellophane tape peeling test, and the state of the remaining coating film after the cellophane tape peeling is visually observed. The cross-cut adhesion was evaluated.
○: The part inserted with the cross cut does not peel off.
(Triangle | delta): The tendency of peeling a little is seen in the part put by the crosscut.
X: Clear peeling is seen in the part put by the cross cut.

<Abrasion resistance measurement>
Scratch resistance is evaluated by visually observing whether or not peeling occurs between the weather resistant resin layer and the plastic film by sliding on the surface of the weather resistant resin layer under a load of 750 g at 100 mm / min using a pencil of any hardness. did.
○: No peeling at 2H △: No peeling at HB ×: There is peeling at HB

<Heat resistance measurement>
For heat resistance, the cross-cut adhesion after 60 minutes was measured at a temperature of 150 ° C.

<Solvent resistance measurement>
The solvent resistance is determined by rubbing the coated surface with a cloth sufficiently containing a solvent (ethyl acetate (hereinafter referred to as EAC), methyl ethyl ketone (hereinafter referred to as MEK), and isopropyl alcohol (hereinafter referred to as IPA)). And the waste coloring degree.
○ The waste cloth is not colored, leaving no trace of rubbing with a solvent on the coated surface.
Δ: The trace of rubbing with the solvent does not remain on the coated surface, but the waste is slightly colored. × The trace of rubbing with the solvent remains on the coated surface, and the waste is colored black.

<Moisture and heat resistance test>
For heat and humidity resistance, cross-cut adhesion and yellowing after 1000 hours, 2000 hours, and 3000 hours were measured under environmental conditions of a temperature of 85 ° C. and a relative humidity of 85% RH.
The yellowing degree is measured from the weather-resistant resin layer side of the solar cell back surface protective sheet 1 using a color difference meter CR-300 (manufactured by Konica Minolta) according to the method described in JIS-Z8722, and L ^* a ^* b ^* Evaluation was based on the Δb value when expressed in a color system.
○: Less than Δb value 2 Δ: Δb value 2 or more and less than 4 ×: Δb value 4 or more XX: Δb value 10 or more

<Weather resistance test>
For weather resistance, a super xenon weather meter (manufactured by Suga Test Instruments Co., Ltd.) was used to measure cross-cut adhesion, yellowing degree, and film loss after 500 cy and 1000 cy under the following conditions.
1) 63 ° C 95% 160W / m2 irradiation + rainfall 12min
2) 63 ° C 50% 160W / m2 irradiation 108min
3) Repeat 1) and 2) as 1 cy.
Film reduction was evaluated by measuring the level difference between the part protected with the weatherproof tape and the unprotected part.
○: Film reduction is less than 1 μm △: Film reduction is 1 μm or more and 5 μm or less X: Film reduction is 5 μm or more and 10 μm or less XX: Film reduction is 10 μm or more

[Examples 2 to 16], [Comparative Example 1-25]
In the same manner as in Example 1, using the solar cell back surface protective sheet 2-41, the cross-cut adhesion to the polyester film of the weather-resistant resin layer, scratch resistance, heat resistance, moist heat resistance, solvent resistance, weather resistance Evaluation was performed. The results are shown in Table 6.

表６に示されるように、実施例１〜１６は、初期特性、耐熱性、耐溶剤性、耐湿熱性、耐候性において申し分のない太陽電池用裏面保護シートであるのに対して、比較例１〜３はアクリル共重合体（Ａ）が十分な水酸基を有していないため、耐溶剤性を有していない。また、比較例４〜９はアクリル共重合体（Ａ）の水酸基の数は十分であるが、比較例４、５はＴｇが高すぎて耐湿熱性に劣り、比較例６、７はＴｇが低すぎて耐候性に劣り、比較例８はアクリル共重合体（Ａ）の分子量が低すぎて、耐溶剤性、耐湿熱性や耐候性において十分でなく、比較例９はアクリル共重合体（Ａ）の分子量が高すぎてプラスチックフィルムとの濡れが悪く、初期から密着性に劣る。比較例１０はアクリル共重合体（Ａ）の水酸基が少なすぎて、硬化が十分に進まず、初期特性、耐熱性、耐湿熱性、耐候性全ての物性で劣り、比較例１１はアクリル共重合体（Ａ）の水酸基が多すぎて、硬化収縮が大きく、湿熱径時での密着性に著しく劣る。比較例１２はアクリル共重合体（Ａ）の芳香環含有量が多すぎるため、耐候性に劣る。

As Table 6 shows, Examples 1-16 are the back surface protection sheets for solar cells which are satisfactory in initial characteristics, heat resistance, solvent resistance, moist heat resistance, and weather resistance, whereas Comparative Example 1 Since ~ 3 does not have a sufficient hydroxyl group, the acrylic copolymer (A) does not have solvent resistance. In Comparative Examples 4 to 9, the number of hydroxyl groups in the acrylic copolymer (A) is sufficient, but in Comparative Examples 4 and 5, the Tg is too high and the heat and humidity resistance is poor, and in Comparative Examples 6 and 7, the Tg is low. It is too inferior in weather resistance, Comparative Example 8 is too low in molecular weight of the acrylic copolymer (A), and is insufficient in solvent resistance, moist heat resistance and weather resistance, and Comparative Example 9 is an acrylic copolymer (A). The molecular weight is too high to wet with the plastic film, resulting in poor adhesion from the beginning. Comparative Example 10 has too few hydroxyl groups in the acrylic copolymer (A), curing does not proceed sufficiently, and initial properties, heat resistance, moist heat resistance, and weather resistance are poor, and Comparative Example 11 is an acrylic copolymer. There are too many hydroxyl groups in (A), the curing shrinkage is large, and the adhesiveness at the time of wet heat diameter is remarkably inferior. Since the comparative example 12 has too much aromatic ring content of an acrylic copolymer (A), it is inferior to a weather resistance.

  In Comparative Examples 13 and 14, the molecular weight of the polyester-based or urethane-based resin (B) is too low, and the solvent resistance, heat-and-moisture resistance, and weather resistance are not sufficient. Comparative Example 15 is a polyester-based or urethane-based resin (B). Is too high to be compatible with the acrylic copolymer (A), and therefore two types of resins are separated in the coating film, resulting in insufficient solvent resistance, moist heat resistance and weather resistance. . In Comparative Example 16, the Tg of the polyester-based or urethane-based resin (B) is too high, the coating film is not flexible and the adhesion to the substrate is not sufficient, and peeling occurs.

Since Comparative Examples 17 and 18 do not contain the polyester-based or urethane-based resin (B), the coating film does not have flexibility and the adhesion to the substrate is not sufficient, and peeling occurs.
In Comparative Examples 19 to 21, since the acrylic copolymer (A) is too little or not contained, a sufficient crosslinking system cannot be constructed, and the solvent resistance and weather resistance are remarkably inferior.
Since Comparative Example 22 does not contain the polyisocyanate compound (C), adhesion to the base material is not sufficient from the beginning, and peeling occurs. In Comparative Example 23, the amount of the polyisocyanate compound (C) is too large, the curing shrinkage is large, and the adhesion at the time of wet heat diameter is extremely inferior. In Comparative Example 24, since the pigment (D) is not contained, the concealability is not sufficient and design properties cannot be imparted, and the weather resistance resin layer is deteriorated, so that the weather resistance is insufficient.

Since Example 25 does not have a weather resistant resin layer, the plastic film (2) is exposed on the surface, and the weather resistance is remarkably inferior.
In Examples 10 and 11, since the polyester-based or urethane-based resin (B) does not have a branched chain, the solvent resistance is slightly inferior. In Example 14, the average particle diameter is 1 μm to 1.1 × t ( μm) particles (E) are not contained, so the scratch resistance is slightly inferior. In Example 15, the particles (E) are larger than the film thickness, so the weather resistance is slightly inferior due to poor concealment. Since the melting point of (D) is less than 120 ° C., it melts at a high temperature and causes a decrease in adhesion.

(I): Solar cell surface sealing sheet positioned on the light receiving surface side of the solar cell (II): Sealing material layer positioned on the light receiving surface side of the solar cell (III): Solar cell (IV): Solar cell Sealant layer located on the non-light-receiving surface side (V): Solar cell back surface protective sheet (1): Weather resistant resin layer (2): Plastic film (3): Adhesive layer (4): Water vapor barrier layer (5 ): Interlayer adhesive layer

Claims (12)

A solar cell back surface protective sheet formed by laminating a weather resistant resin layer (1) having a film thickness t (μm), a plastic film (2) and an adhesive layer (3) in this order,
The weather resistant resin composition (1) in which the weather resistant resin layer (1) contains an acrylic copolymer (A), a polyester or urethane resin (B), a polyisocyanate compound (C), and a pigment (D) ( 1 '),
In the acrylic copolymer (A),
Glass transition temperature is 0 to 70 ° C,
A weight average molecular weight (Mw) of 30,000 to 150,000,
A hydroxyl value of 20 to 150 (mg KOH / g),
The aromatic ring content is up to 50% by weight,
In the polyester-based or urethane-based resin (B),
Glass transition temperature is -30 to 20 ° C,
Number average molecular weight (Mn) is 5,000 to 12,000
A hydroxyl value of 3 to 30 (mg KOH / g),
The aromatic ring content is up to 50% by weight,
The isocyanate group in the polyisocyanate compound (C) is 0.1 to 5 times the sum of the hydroxyl groups of the acrylic copolymer (A) and the polyester or urethane resin (B). A solar cell back surface protection sheet.   The solar cell back surface protection according to claim 1, wherein the ratio of the acrylic copolymer (A) and the polyester or urethane resin (B) is 90/10 to 30/70 (weight ratio). Sheet.   3. The solar cell according to claim 1, wherein the polyester-based or urethane-based resin (B) is at least one selected from the group consisting of a polyester resin, a polyester urethane resin, a polycarbonate urethane resin, and a polyether urethane resin. Back protection sheet.   The solar cell back surface protective sheet according to claim 3, wherein the polyester-based or urethane-based resin (B) has an average number of OH terminal functional groups in one molecule of 2.1 to 5.   The weather resistant resin composition (1 ′) further contains particles (E) having an average particle diameter of 1 μm to 1.1 × t (μm) having a melting point of 120 ° C. or higher or no melting point. The solar cell back surface protection sheet according to any one of claims 1 to 4.   An acrylic copolymer (A) does not have a benzotriazole group, The solar cell back surface protection sheet in any one of Claims 1-5 characterized by the above-mentioned.   The sun according to any one of claims 1 to 6, wherein the pigment (D) is at least one selected from the group consisting of carbon black, perylene black, titanium oxide, zinc oxide, lead oxide, zinc sulfide, and lithobon. Battery back protection sheet.   The solar cell back surface protective sheet according to any one of claims 5 to 7, wherein the particles (E) having an average particle diameter of 1 µm to 1.1 x t (µm) are nitrogen-containing resin particles.   The solar cell back surface protective sheet according to any one of claims 1 to 8, wherein the plastic film (3) is a polyethylene terephthalate film.   The solar cell back surface protective sheet according to any one of claims 1 to 9, further comprising a water vapor barrier layer (2) made of an aluminum foil or a vapor-deposited film between the weather resistant resin layer (1) and the plastic film (2). .   The solar cell back surface protection sheet according to any one of claims 1 to 10, wherein the film thickness t of the weather resistant resin layer (1) is 5 to 30 µm. Solar cell surface sealing sheet (I) positioned on the light receiving surface side of the solar cell, sealing material layer (II) positioned on the light receiving surface side of the solar cell, solar cell (III), non-light receiving surface side of the solar cell The solar cell back surface protection sheet (V) according to any one of claims 1 to 11, wherein the solar cell back surface protective sheet (V) is in contact with the sealant layer (IV) positioned at the surface and the non-light receiving surface side sealant layer (IV). A solar cell module comprising:
The solar cell module, wherein the adhesive layer (3) is in contact with the non-light-receiving surface side sealing agent layer (IV).

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