JP2017101201A - Adhesive composition, solar cell back sheet and solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition for solar cell back sheet having high adhesive force and wet heat resistance as well as high electrical resistance for preventing a short circuit as a solar cell and ultraviolet shielding performance for enhancing durability as a solar cell back sheet.SOLUTION: The problem is solved by an adhesive composition containing (A) a resin having a hydroxyl group, (B) a pigment, (C) a pigment dispersant and (D) a polyisocyanate compound, wherein the pigment (B) is carbon black and the pigment (B) is contained at 15 to 21 mass% in a component of total solid component of the resin (A), the pigment (B), the pigment dispersant (C) and the polyisocyanate compound (D).SELECTED DRAWING: None

Description

  The present invention relates to an adhesive composition used for a solar battery backsheet.

In recent years, from the viewpoint of effective use of resources and prevention of environmental pollution, solar cells that convert sunlight into electric energy have attracted attention and are being actively developed.
Generally, a solar cell is a solar cell such as a silicon power generation element using an EVA (ethylene-vinyl acetate copolymer) film between a glass substrate as a light-receiving surface side transparent protective member and a back surface side protective member (back surface protective sheet). The cell is sealed. These constituent materials are laminated in the order of a light-receiving side transparent protective member, a sheet-shaped sealing material disposed on the front surface side, a solar cell, a sheet-shaped sealing material disposed on the back surface side, and a back surface side protective member. Then, it is heated and laminated to form a solar cell.

  In addition, since solar cells are used outdoors, the members used are required to have high durability, weather resistance, light resistance, and the like. In particular, the back surface protection sheet withstands long-term exposure to sunlight, temperature fluctuations during the day and night, wind pressure and mechanical deformation during construction, and pollutants such as moisture, oxygen, nitrogen oxides and sulfur oxides. It is required to prevent the intrusion of water and protect the power generating element. Such materials include polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polychlorotrifluoroethylene, ethylene tetrafluoride / hexafluoropropylene copolymer, ethylene / tetrafluoroethylene copolymer, etc. In many cases, fluorine resin sheets, metal foils, and the like are used in combination.

  However, the fluorine-based resin sheet is expensive and at the same time is not sufficient from the viewpoint of durability of the power generation module in the long-term high-voltage application, and various structures have been proposed as improved techniques.

  In recent years, therefore, studies have been made to use general-purpose plastic sheets such as polypropylene resin (hereinafter abbreviated as PP resin) and polyethylene terephthalate resin (hereinafter referred to as PET resin) as the back surface protection sheet (see, for example, Patent Documents 1 and 2). ). Since general-purpose plastic sheets have problems with light resistance or adhesion with EVA as a sealing material, inorganic particles may be added to the plastic sheet itself to improve light resistance (see Patent Document 1). Studies have been made to improve adhesion by providing an easy-adhesion coat layer with EVA (see Patent Document 2).

  However, the method described in Patent Document 1 has a problem that the adhesion with EVA cannot be improved and a general-purpose plastic sheet cannot be used. Moreover, in the method described in Patent Document 2, a resin in which a resin skeleton such as an acrylic, epoxy, phenol, polyester, urethane, or styrene resin is modified with a silane compound is used as a resin for the adhesive coat layer. However, it cannot withstand the light resistance test.

JP 2011-18872 A JP 2006-320991 A

In the technology known so far, there is a problem in adhesiveness as described above, or there are problems in durability and light resistance, and an adhesive used for a solar cell backsheet having excellent performance at low cost is used. The current situation is not known.
Therefore, in the present invention, in view of such a conventional technique, it has high adhesive strength and moisture and heat resistance, and has a high electric resistance value for preventing a short circuit as a solar cell and durability as a solar cell back sheet. It is an object of the present invention to provide an adhesive composition for a solar battery backsheet having an ultraviolet shielding ability.

  As a result of intensive studies for solving the problems, the present inventors have found that an adhesive composition containing a hydroxyl group-containing resin (A), pigment (B), pigment dispersant (C) and polyisocyanate compound (D). The pigment (B) is carbon black, and the pigment (B) is added to the component obtained by adding the solid contents of the resin (A), the pigment (B), the pigment dispersant (C), and the polyisocyanate compound (D). The adhesive composition containing ˜21% by mass led to the solution of the problem.

  ADVANTAGE OF THE INVENTION According to this invention, while having high adhesive force and heat-and-moisture resistance, the adhesive composition for solar cell backsheets provided with the high electrical resistance value and ultraviolet-ray shielding ability can be provided.

In order to solve the above problems, the present invention includes the following items.
1. In the adhesive composition containing the resin (A) having a hydroxyl group, the pigment (B), the pigment dispersant (C) and the polyisocyanate compound (D),
The pigment (B) is carbon black,
An adhesive composition containing 15 to 21% by mass of the pigment (B) in a component in which the solid contents of the resin (A), the pigment (B), the pigment dispersant (C) and the polyisocyanate compound (D) are combined;
2. The pigment dispersant (C) is contained in an amount of 0.9 to 3.3% by mass in the total component of the resin (A), pigment (B), pigment dispersant (C) and polyisocyanate compound (D). 1. The adhesive composition according to
3. 1. The hydroxyl value of the resin (A) having a hydroxyl group is 1 to 200 mgKOH / g. Or 2. The adhesive composition according to
4). 1. The hydroxyl group-containing resin (A) is at least one selected from the group consisting of an acrylic resin, a polyester resin, a urethane resin, and a fluororesin. ~ 3. The adhesive composition according to any one of
5). 1. Number average molecular weight of resin (A) having a hydroxyl group is 5,000 to 50,000, and glass transition temperature is 20 to 110 ° C. ~ 4. The adhesive composition according to any one of
6). Further, it contains an epoxy resin. ~ 5. The adhesive composition according to any one of
7.1. ~ 6. A laminated polyester film in which a cured film of the adhesive composition according to any of the above is laminated on a polyester resin film,
8.7. A solar battery back sheet having a layer composed of the laminated polyester film according to claim 1,
9.8. A solar cell obtained by laminating the solar cell backsheet described in 1 and a sealing material constituting the solar cell module.

<Resin having hydroxyl group (A)>
The resin (A) having a hydroxyl group used in the present invention is not particularly limited as long as the hydroxyl value of the resin is 1 to 200 mgKOH / g. For example, an acrylic resin, a polyester resin, a urethane resin, or a fluorine resin each having a hydroxyl group. These may be used alone or in combination of two or more.

  The resin (A) having a hydroxyl group used in the present invention has a hydroxyl value satisfying 1 to 200 mgKOH / g, in particular, having a hydroxyl value in the range of 4 to 100 mgKOH / g, adhesion to EVA, durability and It is preferable from the viewpoint of hydrolysis resistance. When the hydroxyl value is less than 1, curing of the coating film hardly progresses, and adhesion and durability with EVA are inferior. On the other hand, when the hydroxyl value is larger than 200, the curing shrinkage is too large, so that the adhesion with EVA is deteriorated.

  The acrylic resin having a hydroxyl group used in the present invention refers to a linear resin having a hydroxyl group, obtained by polymerizing an acrylic ester or a methacrylic ester as an essential component. Hereinafter, acrylic and methacryl are collectively referred to as (meth) acryl.

  Such an acrylic resin can be easily obtained, for example, by copolymerizing a carboxylic acid group-containing monomer such as (meth) acrylic acid, itaconic acid, maleic anhydride, etc. as necessary with (meth) acrylic acid ester as an essential component. Can be manufactured. Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and tert-butyl. (Meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate Etc.

  In carrying out copolymerization using (meth) acrylic acid ester as an essential component, for example, hydroxyl-containing (meth) acrylic acid ester such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, etc. By using together, the hydroxyl-containing (meth) acrylic resin by which the hydroxyl group was introduce | transduced into the side chain of the acrylic resin frame | skeleton can be obtained.

  Such a hydroxyl group-containing acrylic resin has an ethylene glycol di (methacrylate) content as long as it does not significantly impair the characteristics such as low viscosity and excellent flexibility of the cured film due to being linear. ) Acrylic resin polymerized using a small amount of 2-6 (meth) acryloyl group-containing polymerizable monomers such as acrylate, trimethylolpropane tri (meth) acrylate and hexa (meth) acrylate. May be.

  Examples of such an acrylic resin having a hydroxyl group include “Acridic” series manufactured by DIC Corporation and “Aclit” series manufactured by Taisei Fine Chemical Co., Ltd. For example, as a commercial item of an acrylic resin, DIC Corporation make, brand name: ACRYDIC A-808-T, 57-451 can be mentioned.

  The polyester resin having a hydroxyl group used in the present invention refers to a linear resin having an excess hydroxyl group obtained by reacting glycol with dibasic acid or a derivative thereof as essential components. Of course, in place of the dibasic acid, an ester-forming derivative such as a dibasic acid anhydride or a dibasic acid lower alkyl ester is used, and not only in a polycondensation reaction, but also in an addition reaction or a transesterification reaction, a polyester resin Can also be obtained.

  Examples of the polyester resin include aliphatic glycols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, decanediol, and cyclohexanedimethanol, and succinic acid, adipic acid, sebacic acid, and suberin fumarate. Aliphatic polyester resins obtained by reacting acid, azelaic acid, aliphatic dibasic acid such as 1,10-decamethylenedicarboxylic acid and cyclohexanedicarboxylic acid as essential raw material components, and fats such as ethylene glycol, propylene glycol and butanediol An aromatic polyester resin obtained by reacting an aromatic glycol with an aromatic dibasic acid such as terephthalic acid, isophthalic acid or naphthalenedicarboxylic acid as an essential raw material component.

  The polyester resin having such a hydroxyl group is not limited to the above-mentioned glycol or dibasic acid, but trimellitic acid, as long as the characteristics such as low viscosity and excellent flexibility of the cured film are not greatly impaired. Polyester resin obtained by using a small amount of a compound containing 3 to 4 active hydrogen groups such as a hydroxyl group or a carboxy group, such as pyromellitic acid, tromethylolpropane, pentaerythritol, etc. .

  The polyester resin tends to have a higher Tg by containing more benzene rings and naphthalene rings in the main chain. For example, the target substrate to be coated is PET, PBT (polybutylene terephthalate), Since affinity with PEN (polyethylene naphthalate) increases, it is preferable to use an aromatic polyester resin rather than an aliphatic polyester resin in the present invention. However, since more benzene rings and naphthalene rings are contained in the main chain, crystallinity, melting point, etc. tend to increase, and fluidity and applicability tend to be lowered.

  Therefore, the polyester resin is preferably a polyester resin having a glass transition temperature (Tg) of 20 to 110 ° C. according to differential scanning calorimetry (DSC method). In the present invention, Tg of 40 to 100 obtained by using 25 mol% or more of aliphatic glycol having 2 to 4 carbon atoms in all alcohols and 30 mol% or more of aromatic dibasic acid in all polybasic acids. It is more preferable to use an aromatic polyester resin at ° C.

  Examples of the polyester resin having a hydroxyl group include “Byron” series manufactured by Toyobo Co., Ltd., “Eritel” series manufactured by Unitika Ltd., and more specifically, for example, manufactured by Unitika Ltd., trade name: Elitel UE-3210, XA-0611.

  The polyurethane resin having a hydroxyl group used in the present invention is obtained by, for example, reacting a polyisocyanate compound and a compound having at least two hydroxyl groups in one molecule at a ratio such that the hydroxyl group is excessive with respect to the isocyanate group. can get. Examples of the polyisocyanate compound used at that time include hexamethylene diisocyanate, toluene diisocyanate, m-xylylene diisocyanate, and isophorone diisocyanate. Examples of the compound having at least two hydroxyl groups in one molecule include the polyhydric alcohols, polyester diol, polyethylene glycol, polypropylene glycol, and polycarbonate diol.

  The fluororesin having a hydroxyl group used in the present invention refers to a linear resin having a hydroxyl group obtained by polymerizing a fluorovinyl monomer as an essential component.

  Examples of the fluorine vinyl monomer include vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, 1,1,3,3,3-pentafluoropropylene, 2,2,3,3- Including pure fluoroolefins such as tetrafluoropropylene, 1,1,2-trifluoropropylene or 3,3,3-trifluoropropylene, chlorotrifluoroethylene, bromotrifluoroethylene, 1 -So-called fluoroolefins in a broad sense including compounds having a halogen atom other than a fluorine atom such as chloro-1,2-difluoroethylene or 1,1-dichloro-2,2-difluoroethylene Can be mentioned.

Furthermore, as an essential component of the fluororesin, for copolymerization, for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxyl-containing (meth) acrylate such as hydroxybutyl (meth) acrylate, or By using a hydroxyl group-containing vinyl ether such as 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether in combination, a fluororesin having a hydroxyl group in which a hydroxyl group is introduced into the side chain of the fluororesin skeleton can be obtained. Examples of the fluororesin having a hydroxyl group include “Fluonate” series manufactured by DIC Corporation.
In the present invention, a known and commonly used polyolefin resin having a hydroxyl group can also be used, and examples thereof include the Unistor series.

  The resin (A) having a hydroxyl group used in the present invention satisfies the number average molecular weight of 5,000 to 50,000, preferably the number average molecular weight is 10,000 to 30,000. It is more preferable at the point which is excellent in hydrolysis resistance. The above-described resin having a hydroxyl group having a molecular weight dissolves in an organic solvent, and exhibits outstanding adhesion to EVA and hydrolysis resistance without greatly impairing the fluidity of the solution.

  The resin (A) having a hydroxyl group used in the present invention satisfies a glass transition temperature of 20 to 110 ° C. in order to form a coating film having excellent adhesion on a flexible substrate such as a plastic film. The glass transition temperature is more preferably 40 to 100 ° C. The above-described resin having a hydroxyl group having a glass transition temperature can satisfy the adhesion with EVA, the blocking resistance, and the hydrolysis resistance in a well-balanced manner.

<Pigment (B)>
Examples of the pigment that can be preferably used in the present invention include carbon black. The carbon black used in the present invention may be a commonly used one, but carbon black produced by the furnace method or the channel method is particularly preferred because it can provide a high electric resistance value and blackness.

  In addition, if necessary, the following pigments may be used in combination as long as the effects of the present invention are not impaired. In this case, usable pigments are not particularly limited. For example, extender pigments, white pigments, black pigments, gray pigments, red pigments described in the Paint Material Handbook 1970 edition (edited by the Japan Paint Industry Association) Examples thereof include organic pigments and inorganic pigments such as pigments, brown pigments, green pigments, blue pigments, metal powder pigments, luminescent pigments, and pearl pigments, and plastic pigments. Specific examples of these colorants include various types, and examples of organic pigments include various insoluble azo pigments such as Bench Gin Yellow, Hansa Yellow, Raked 4R, etc .; Soluble properties such as Raked C, Carmine 6B, Bordeaux 10 and the like. Azo pigments;

  Various (copper) phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; various chlorine dyeing lakes such as rhodamine lake and methyl violet lake; various mordant dye pigments such as quinoline lake and fast sky blue; anthraquinone pigment; Various vat dyes such as thioindigo pigments and perinone pigments; various quinacridone pigments such as Cincacia Red B; various dioxazine pigments such as dioxazine violet; various condensed azo pigments such as chromoftal; aniline Black etc. are mentioned.

  Examples of inorganic pigments include various chromates such as chrome lead, zinc chromate, and molybdate orange; various ferrocyan compounds such as bitumen; titanium oxide, zinc white, mapico yellow, iron oxide, bengara, chrome oxide Various metal oxides such as green and zirconium oxide; various sulfides or selenides such as cadmium yellow, cadmium red and mercury sulfide;

  Various sulfates such as barium sulfate and lead sulfate; Various silicates such as calcium silicate and ultramarine blue; Various carbonates such as calcium carbonate and magnesium carbonate; Various phosphates such as cobalt violet and manganese purple; Aluminum Various metal powder pigments such as powder, gold powder, silver powder, copper powder, bronze powder and brass powder; flake pigments of these metals, mica flake pigments; mica flake pigments coated with metal oxides, mica-like iron oxide Examples thereof include metallic pigments such as pigments and pearl pigments; graphite and carbon black.

  Examples of extender pigments include precipitated barium sulfate, powder, precipitated calcium carbonate, calcium bicarbonate, cryolite, alumina white, silica, hydrous finely divided silica (white carbon), ultrafine anhydrous silica (Aerosil), and silica sand (silica). Sand), talc, precipitated magnesium carbonate, bentonite, clay, kaolin, ocher and the like.

  Furthermore, examples of the plastic pigment include DIC Corporation Grandol PP-1000, PP-2000S, and the like.

In the present invention, the pigment (B) that is carbon black is 15 to 21 mass in the total component of resin (A), pigment (B), pigment dispersant (C) and polyisocyanate compound (D). % Content.
This range is particularly preferable for solving the problems of the present invention because it is excellent in adhesion to EVA, weather resistance, storage stability, and the like.

<Pigment dispersant (C)>
In the present invention, the pigment dispersant (C) is added in an amount of 0.9 to 3 in a component in which the solid contents of the resin (A), the pigment (B), the pigment dispersant (C) and the polyisocyanate compound (D) are combined. It is characterized by containing 3 mass%. Here, when it is less than 0.9% by mass, the electric resistance value or the ultraviolet shielding ability is unfavorably deteriorated.
Examples of the pigment dispersant (C) that can be used in the present invention include those known and commonly used, and examples thereof include polyester-based, acrylic-based, urethane-based, phosphate ester-based, synergist, and aminoalkyd. Since it is a combination with carbon black, a synergist or a polyester is particularly preferable and can be used alone or in combination.

<Polyisocyanate compound (D)>
Examples of the polyisocyanate compound (D) used in the present invention include organic compounds having at least two isocyanate groups in the molecule. Examples of the organic polyisocyanate compound include tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), lysine diisocyanate, trimethylhexamethylene diisocyanate, Polyisocyanates such as 1,3- (isocyanatomethyl) cyclohexane, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate; adducts of these polyisocyanates, burettes of these polyisocyanates, or of these polyisocyanates Derivatives (modified products) of polyisocyanates such as isocyanurates are exemplified.

The polyisocyanate compound (D) used in the present invention may be appropriately selected depending on the application to be used. However, an aromatic system such as tolylene diisocyanate may turn yellow and requires better weather resistance. Is preferably an aliphatic or alicyclic non-yellowing polyisocyanate. It is not preferable that the cured coating film is colored on a transparent substrate such as a polyester resin film and the transparency is lowered in view of deterioration of visibility. Therefore, it is preferable to use non-yellowing polyisocyanates such as aliphatic or alicyclic non-yellowing polyisocyanates such as hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI).
The curing agent exhibits a certain level of performance only with the polyisocyanate compound (D), but imparts a high degree of hydrolysis resistance to the cured coating by actively using the polyisocyanate compound and the epoxy resin described later. I can do it.

  The blending ratio of the hydroxyl group-containing resin (A) and the polyisocyanate compound (D) is determined based on the solid content hydroxyl equivalent (a) of the hydroxyl group-containing resin (A) and the solid content isocyanate equivalent (b) of the polyisocyanate compound (D). ) Equivalent ratio [(a) / (b)] is 0.5 to 5, preferably 0.6 to 2.0.

<Epoxy resin>
An epoxy resin may be used in combination with the composition of the present invention for the purpose of imparting higher hydrolysis resistance. Examples of the epoxy resin include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, and bisphenol AD type epoxy resin; orthocresol novolac type epoxy resin, phenol novolac type epoxy Resin, naphthol novolac epoxy resin, bisphenol A novolac epoxy resin, brominated phenol novolac epoxy resin, alkylphenol novolac epoxy resin, bisphenol S novolac epoxy resin, alkoxy group-containing novolac epoxy resin, brominated phenol novolac epoxy Novolac type epoxy resins such as resins; other phenol aralkyl type epoxy resins (commonly known as epoxies of XILOCK resin) ), Diglycidyl ether of resorcin, diglycidyl ether of hydroquinone, diglycidyl ether of catechol, biphenyl type epoxy resin, tetramethylbiphenyl type epoxy resin, sulfur-containing epoxy resin, stilbene type epoxy resin, etc., Alicyclic epoxy resin such as hydrogenated bisphenol A type epoxy resin, triglycidyl isocyanurate, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadiene-phenol addition reaction type epoxy resin, biphenyl modified novolak type Epoxy resins (epoxidized products of polyphenol resins in which phenol nuclei are linked by bismethylene groups), alkoxy group-containing novolac type epoxy resins, tetrabromobisphenol A type epoxy resins Such as resin and the like. Moreover, the said epoxy resin may be used independently and may mix 2 or more types.

Among these, it is preferable to use an aromatic epoxy resin such as a bisphenol A type epoxy resin because of good adhesion and corrosion resistance.
Specific examples of the bisphenol A type epoxy resin include “EPICLON 850, 860, 1050, 1055, 2055” manufactured by DIC Corporation, “jER828, 834, 1001, 1002, 1004, 1007” manufactured by Mitsubishi Chemical Corporation, and the like. Is mentioned.
Moreover, the epoxy resin which has 2 or more of epoxy groups in 1 molecule, 1 or more of hydroxyl groups in 1 molecule, and an epoxy compound whose weight average molecular weight is 3000 or less is an essential component may be sufficient. .

The case where the said epoxy compound is mix | blended in the ratio of 0.01-30 mass parts with respect to 100 mass parts of resin (A) which has the said hydroxyl group is preferable.
When the amount is less than 0.01 parts by mass, the adhesive force to the substrate is lowered, which is not preferable.
Moreover, when more than 30 mass parts, the cohesive force of a coating film becomes low and is unpreferable.

  From the viewpoint of viscosity adjustment, the adhesive composition of the present invention, particularly the above-mentioned main agent, does not have reactivity with the raw materials included therein, and can contain an organic solvent that dissolves the raw materials. Specifically, for example, hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate and butyl acetate, ether solvents such as dioxane and ethylene glycol diethyl ether , Aliphatic hydrocarbons such as pentane, hexane and heptane.

  If necessary, the adhesive composition of the present invention may contain other additives other than those described above. Examples of the additive include additives generally used in resin compositions that form films and coating films. Examples of additives include leveling agents; inorganic fine particles such as colloidal silica and alumina sol; organic fine particles based on polymethyl methacrylate; antifoaming agents; anti-sagging agents; silane coupling agents; viscosity modifiers; Metal deactivator; Peroxide decomposing agent; Flame retardant; Reinforcing agent; Plasticizer; Lubricant; Rust preventive agent; Fluorescent whitening agent; Inorganic heat absorber; Flameproof agent; And so on.

  The adhesive composition of the present invention can be usually prepared by preparing a main component premix in which components other than the polyisocyanate compound, which is a curing agent, are blended in advance, and mixing this with a polyisocyanate compound. .

The adhesive composition of the present invention can be applied to various substrates and dried to laminate a cured coating film having adhesiveness on the substrate. The amount of application to the substrate is not particularly limited, but for example, it is selected from the range of 0.5 to 20 g / m ² , especially 1 to 10 g / m ^2. It is preferable at the point which can provide. For this coating, for example, a gravure coater, a micro gravure coater, a reverse coater, a bar coater, a roll coater, a die coater or the like can be used.

  Moreover, it is preferable that the laminated body which apply | coated the adhesive composition of this invention performs aging after preparation. The aging conditions are from room temperature to 100 ° C. and for 12 to 240 hours, during which the curing reaction proceeds.

  Examples of the base material in this case include paper, olefin resin, acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride resin, fluorine resin, poly (meth) acrylic resin, and carbonate resin. And polyamide resin, polyimide resin, polyphenylene ether resin, synthetic resin film obtained from polyphenylene sulfide resin and polyester resin, copper foil, metal foil such as aluminum foil, and the like. The thickness of the substrate is not particularly limited, and can be selected from, for example, 10 to 400 μm. However, the easy-adhesive composition of the present invention can be applied to a substrate with a small amount of application and low-temperature and short-time drying. Since it exhibits excellent adhesion without giving any influence such as sag and can provide excellent weather resistance, it is most suitable to be applied to a substrate having a softening temperature of 180 ° C. or less at 30 to 80 μm.

  Low-temperature and short-time drying eliminates the inconvenience of warping the substrate and peeling the coating film, and provides excellent adhesion to the substrate, preventing deterioration of the laminate more effectively. It is preferable to use a polyester resin film as the base material because it can be used. The laminated polyester resin film in which the cured coating film of the easy-adhesive composition of the present invention is laminated on the polyester resin film has the above-described excellent properties.

  In particular, from the drying at a relatively low temperature of 160 ° C. or less for a short time of 1 minute or less, the above-mentioned inconvenience is not caused to the thin film base material, and excellent adhesion to the base material is obtained, and the moisture resistance of the laminated body is obtained. As a base material, it is more preferable to use a PET film in that deterioration based on heat resistance and hydrolysis resistance can be more effectively prevented. The laminated polyester resin film in which the cured coating film of the easy-adhesive composition of the present invention is laminated on a PET film has the above-described excellent properties. In particular, it is suitable as a laminated polyester resin film for a solar battery backsheet.

  In order to improve the adhesion between the polyester resin film and the cured coating film, a surface treatment may be performed on the surface on which the cured coating film of the polyester resin film is formed. Examples of the surface treatment include corona treatment, plasma treatment, ozone treatment, flame treatment, and radiation treatment.

  In the solar cell module of the present invention, the configuration of the transparent protective member, the solar cell, the sealing resin that covers the entire surface of the solar cell, and the back sheet is the same as that of a conventionally known solar cell module. This is not a configuration specific to the present invention.

  That is, as a cell for solar cells, a transparent electrode layer, an optical semiconductor layer, and a back electrode layer are laminated on a substrate and separated by separation grooves so as to form a plurality of photoelectric conversion cells, and these photoelectric conversion cells are An integrated solar cell element electrically connected in series is generally used, and silicon, thin-film polycrystalline silicon, or the like can be used as the photoelectric conversion layer in the optical semiconductor layer. Furthermore, an electrical output can be taken out of the module from the solar cell.

  As the resin used as the sealing resin, EVA is mainly used, but PVB (polyvinyl butyral), PIB (polyisobutylene), olefin resin (especially graft-modified polyethylene resin), ionomer resin, silicon resin, etc. may be used. it can. Usually, EVA used as a sealing resin for a solar cell module has a vinyl acetate content of 10 to 40% by weight, and heat or light is used to ensure the heat resistance and physical strength of the solar cell module. EVA is cross-linked by the above.

  In the case of performing thermal crosslinking, an organic peroxide is usually used, and one that decomposes at a temperature of 70 ° C. or higher to generate radicals is used. Usually, those having a decomposition temperature of 50 ° C. or more with a half-life of 10 hours are used, and 2,5-dimethylhexane-2,5-dihydroxyperoxide, 2,5-dimethyl-2,5-di (t-butyl) Peroxy) hexyne-3, di-t-butyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, dicumyl peroxide, α, α '-Bis (t-butylperoxyisopropyl) benzene, n-butyl-4,4-bis- (t-butylperoxy) valerate, t-butylperoxybenzoate, benzoyl peroxide and the like are used.

  In the case of photocuring, a photosensitizer is used, and hydrogen abstraction type (bimolecular reaction type) such as benzophenone, methyl orthobenzoylbenzoate, 4-benzoyl-4'-methyldiphenyl sulfide, isopropylthioxanthone, etc. As the internal cleavage type initiator, α-hydroxyalkylphenone type such as benzoin ether, benzyldimethyl ketal, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl, etc. Phenyl ketone, alkylphenyl glyoxylate, diethoxyacetophenone and the like can be used. Further, as α-aminoalkylphenone type, 2-methyl-1- [4 (methylthio) phenyl] -2-morpholinopropane-1, 2-benzyl-2-dimethylamino-1- (4-morpholino) Phenyl) -butanone-1 and the like, and acylphosphine oxide and the like are also used.

  A silane coupling agent is also blended in consideration of adhesion to the glass plate constituting the solar cell module, and vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, Vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane , Γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, and the like.

  Furthermore, an epoxy group-containing compound may be blended for the purpose of promoting adhesion and curing. Examples of the epoxy group-containing compound include triglycidyl tris (2-hydroxyethyl) isocyanurate, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, acrylic glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, phenol glycidyl ether, pt-butylphenyl glycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester , Glycidyl methacrylate, butyl glycidyl ether and other compounds, oligomers containing an epoxy group with a molecular weight of several hundred to several thousand, and polymers with a weight average molecular weight of several thousand to several hundred thousand. Some cases are there.

Further, an acryloxy group, methacryloxy group or allyl group-containing compound is added for the purpose of improving the crosslinking resin, adhesion, mechanical strength, heat resistance, heat and humidity resistance, weather resistance, etc. Acrylic acid derivatives such as their alkyl esters and amides are most common. In this case, as the alkyl group, in addition to an alkyl group such as methyl, ethyl, dodecyl, stearyl, lauryl, cyclohexyl group, tetrahydrofurfuryl group, aminoethyl group, 2-hydroxyethyl group, 3-hydroxypropyl group, A 3-chloro-2-hydroxypropyl group and the like can be mentioned. Further, esters of (meth) acrylic acid and polyfunctional alcohols such as ethylene glycol, triethylene glycol, polyethylene glycol, glycerin, trimethylolpropane, pentaerythritol and the like are also used. A typical amide is acrylamide. Further, as the allyl group-containing compound, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl isophthalate, diallyl maleate and the like are blended.

  Furthermore, an inorganic compound for imparting flame retardancy, an ultraviolet absorber for imparting weather resistance, and an antioxidant for preventing oxidative degradation are variously blended. That is, EVA which comprises a solar cell module is a resin composition which mix | blended various additives in order to satisfy | fill the function requested | required as a solar cell module.

As an example of a method for integrating as a solar cell module, a vacuum laminating method can be given. This method is, for example, a solar cell in which a transparent protective member, a sealing resin on the transparent protective member side, and a wiring are provided on a dummy glass or a metal plate on a heating plate of a vacuum laminating apparatus heated to 100 to 150 ° C. The cell, the back sheet side sealing resin, and the back sheet are laminated in this order and allowed to stand. Thereafter, the vacuum laminating apparatus is closed and pressure reduction is started. After this pressure reduction state is maintained for 3 to 10 minutes, air is introduced from the air supply / exhaust pipe, and the rubber diaphragm is pressed against the laminated body by pressure difference to pressurize. . Although depending on the type of sealing resin, the heated vacuum laminating step is completed by holding this state for 10 to 40 minutes.
The vacuum laminating method is only an example, and various laminating methods can be applied.

<Other additives>
In the present invention, known and commonly used thermoplastic elastomers, tackifiers, catalysts, phosphoric acid compounds, melamine resins, silane coupling agents, or reactive elastomers can be used as other additives. The content of these additives can be appropriately adjusted and used as long as the function of the adhesive of the present invention is not impaired.

<Laminated body>
In the laminate of the present invention, the adhesive composition of the present invention is bonded to a metal layer such as an aluminum foil and one or several plastic layers such as a polyolefin sheet such as polyethylene or polypropylene, or a polyester such as polyethylene terephthalate. It is obtained.

  The adhesive composition of the present invention can be used in an appropriate ratio, for example, in an appropriate solvent or dispersant such as an ester solvent, a ketone solvent, an aromatic hydrocarbon, an aliphatic hydrocarbon, and an alicyclic hydrocarbon. The adhesive layer can be formed by dissolving / dispersing and applying to a metal foil and drying using a known coating method such as a roll coating method, a gravure coating method, a bar coating method or the like.

The dry coating weight of the adhesive composition of the present invention is preferably in the range of 0.5 to 20.0 g / m ² . If it is less than 0.5 g / m ² , there will be a difficulty in continuous uniform application, while if it exceeds 20.0 g / m ² , the solvent detachability after application will be reduced, workability will be significantly reduced, and the residual solvent Problems arise.

After the adhesive composition of the present invention is applied to one of the metal foils, the plastic layer is overlaid and bonded by dry lamination (dry lamination method) to obtain the laminate of the present invention. The temperature of the laminate roll is preferably about room temperature to about 120 ° C., and the pressure is preferably about 3 to 300 kg / cm ² .
Moreover, it is preferable that the laminated body of this invention performs aging after preparation. Aging conditions are preferably a temperature of 25 to 80 ° C. and a time of 12 to 240 hours, during which adhesive strength is generated.

  Hereinafter, the present invention will be specifically described by way of examples. The notation “parts” indicates parts by mass.

(Example 1) to (Example 6) and (Comparative Example 1) to (Comparative Example 4)
As shown in Table 1 and Table 2 below, using a resin (A) having a hydroxyl group, a pigment (B), a fatty acid derivative (C), a polyisocyanate compound (D), and an epoxy resin, a main component and a curing agent component The present invention and the conventional easy-adhesive composition were prepared.

The easy-adhesive composition was applied to “E5001” (PET film manufactured by Toyobo Co., Ltd.) so that the coating amount after drying was ² to 4 g / m ² , dried at 120 ° C. for 30 seconds, and easily adhered. After forming the layer, it was aged at 40 ° C. for 3 days.

(Production method of adhesive evaluation sample with EVA)
Two sheets of the coated product provided with the easy-adhesion layer were cut into a width of 50 mm and a length of 100 mm, and one sheet of an EVA sheet (manufactured by Sanvic Co., Ltd.) cut into a width of 50 mm and a length of 100 mm was prepared. .

  Laminate so that the easy-adhesion layer is in contact with the EVA side, and then use a vacuum laminator to evacuate the resulting laminate at 150 ° C. for 5 minutes and hold it for 15 minutes to allow the crosslinking reaction to proceed. It was.

(Evaluation method for adhesion to EVA)
For adhesion to EVA, the sample for evaluation of easy adhesion is sandwiched between the upper and lower clips of a tensile tester (A & D Tensilon Tester Co., Ltd.) and the backsheet of the non-adhesive part is sandwiched between autographs. Using a T-type peeling method with a crosshead speed of 200 mm and a width of 200 m
The peel strength at m / min was measured. Here, the unit of Table 1 and Table 2 is “N / 10 mm”.

  Furthermore, the sample for evaluation of easy adhesion was subjected to a pressure cooker test (PCT) for 24 hours (test conditions: 121 ° C., relative humidity was 100%), and the peel strength after the wet heat resistance test was evaluated under the same conditions as described above. . Similarly, the unit described in Table 1 and Table 2 is “N / 10 mm”.

(Evaluation method of light transmittance)
In order to evaluate the ultraviolet shielding ability, the light transmittance was measured as follows.
The easy-adhesive composition was applied to “E5001” (PET film manufactured by Toyobo Co., Ltd.) so that the coating amount after drying was ² to 4 g / m ² , dried at 120 ° C. for 30 seconds, and easily adhered. After forming the layer, aging was performed at 40 ° C. for 3 days to prepare a coated product.
In the measurement wavelength region of 290 to 400 nm, the transmittance (%) for each wavelength of ultraviolet rays irradiated on the coated material was measured using an ultraviolet / visible spectrophotometer (UV-3600, manufactured by Shimadzu Corporation).

(Insulation evaluation method)
The easy-adhesive composition was applied to “E5001” (PET film manufactured by Toyobo Co., Ltd.) so that the coating amount after drying was ² to 4 g / m ² , dried at 120 ° C. for 30 seconds, and easily adhered. After forming the layer, aging was performed at 40 ° C. for 3 days to prepare a coated product.
The surface resistivity (Ω / □) of the coated surface was measured using a resistivity meter (Hiresta-UP MCP-HT450 manufactured by Mitsubishi Chemical Corporation) in a constant temperature and humidity environment of 25 ° C. and 50%.

<Resin (A)>
Acrydic 57-451 (manufactured by DIC Corporation): hydroxyl group-containing acrylic resin, solid content 55%
Unistar P-901 (manufactured by Mitsui Chemicals): hydroxyl group-containing polyolefin resin, hydroxyl value 50 mgKOH / g, solid content 22%
<Pigment (B)>
Special 100 (powder) (manufactured by Orion Engineered Carbons): carbon black <dispersant (C)>
Solsols 24000GR (manufactured by Nippon Lubrizol Co., Ltd.): polyester-based dispersant, solid content 100%
Solsols 5000 (manufactured by Nippon Lubrizol Co., Ltd.): Phthalocyanine ammonium salt-based dispersant, solid content 100%
<Polyisocyanate (D)>
-N3300 (manufactured by Sumika Bayer Urethane Co., Ltd.): Non-yellowing polyisocyanate, NCO% 21.8, solid content 100%
<Epoxy resin>
-Epicron 860-80SE (manufactured by DIC Corporation): BPA type epoxy resin, epoxy equivalent 240, solid content 80%
Denacol EX-321 (manufactured by Nagase ChemteX Corporation): polyfunctional glycidyl ether compound, epoxy equivalent 140

From the above, it is clear that in the examples within the technical scope of the present invention, it is possible to provide an adhesive composition excellent in adhesive strength, light transmittance, and conductivity.
On the other hand, in Comparative Examples 1 to 3 outside the technical scope of the present invention (the contents of the pigment and the dispersant are low), both the light transmittance and the conductivity were inferior. In Comparative Example 4 (the pigment content is within the range, but the dispersant content is large), the conductivity was inferior.

  The laminated polyester film in which the cured film of the adhesive composition of the present invention is laminated on a polyester resin film can be used as a back sheet for a solar cell, and the back sheet is used as a solar cell by bonding with a sealing material. Can be used.

Claims (9)

In the adhesive composition containing the resin (A) having a hydroxyl group, the pigment (B), the pigment dispersant (C) and the polyisocyanate compound (D),
The pigment (B) is carbon black,
The adhesive composition which contains 15-21 mass% of pigments (B) in the component which totaled solid content of resin (A), pigment (B), pigment dispersant (C), and polyisocyanate compound (D). The pigment dispersant (C) is contained in an amount of 0.9 to 3.3% by mass in the total component of the resin (A), pigment (B), pigment dispersant (C) and polyisocyanate compound (D). The adhesive composition according to claim 1. The adhesive composition according to claim 1 or 2, wherein the hydroxyl value of the hydroxyl group-containing resin (A) is 1 to 200 mgKOH / g. The adhesive composition according to any one of claims 1 to 3, wherein the resin (A) having a hydroxyl group is at least one selected from the group consisting of an acrylic resin, a polyester resin, a urethane resin, and a fluororesin. The adhesive composition according to any one of claims 1 to 4, wherein the resin (A) having a hydroxyl group has a number average molecular weight of 5,000 to 50,000 and a glass transition temperature of 20 to 110 ° C. Furthermore, the adhesive composition in any one of Claims 1-5 containing an epoxy resin. A laminated polyester film in which a cured film of the adhesive composition according to claim 1 is laminated on a polyester resin film. The solar cell backsheet which has a layer comprised with the lamination | stacking polyester film of Claim 7. The solar cell formed by bonding the solar cell backsheet of Claim 8, and the sealing material which comprises a solar cell module.