JP6299149B2 - COATING COMPOSITION, SOLAR CELL MODULE BACK SHEET, AND SOLAR CELL MODULE - Google Patents

Description

The present invention relates to a coating composition, a solar cell module backsheet, and a solar cell module.

A solar battery module is usually composed of a solar battery cell, a sealing material for sealing the solar battery cell, a surface layer and a back sheet provided on the light receiving surface side (front surface side) and the back surface side of the sealing material. Composed.

The solar cell module is used outdoors. For this reason, the back sheet of the solar cell module is required to have high weather resistance, moisture resistance, heat resistance, and insulation, as with the surface layer on the light receiving surface side. Moreover, the performance which resists ultraviolet degradation by reflected light is also required.

As a back sheet of a solar cell module, one in which a fluororesin layer is formed on a base material is known (Patent Document 1). Such a fluororesin layer is also formed by applying a coating composition containing a fluorine-containing polymer, a pigment, an organic solvent, etc. on a substrate and curing it (Patent Document 2).

In addition, in the coating composition for forming such a back sheet, it is desired that the pigment is added from the viewpoint of beautifying the appearance of the solar cell module. Calcium, composite metal such as carbon black as a black pigment, Cu—Cr—Mn alloy, etc. are usually blended (Patent Document 3).

JP 2008-227203 A JP 2010-238760 A International Publication No. 2007/010706 Pamphlet

However, when carbon black is used as a pigment, there is a problem in that carbon black settles when the coating composition is stored for a long period of time.

An object of this invention is to provide the coating composition which can form the coating film excellent in the pigment dispersibility and coating-liquid stability, and excellent in ultraviolet-ray shielding property in view of the said present condition.

As a result of examining these requirements, the present inventors have used a compound having a base number and an acid number within a specific range as a dispersant in a coating composition containing a curable functional group-containing fluorine-containing polymer and carbon black. As a result, it was found that the pigment dispersibility and the coating liquid stability of the coating composition can be surprisingly improved, and the present invention has been completed. It has also been found that the use of a specific dispersant improves the ultraviolet shielding properties of the resulting coating film.

That is, the present invention includes a curable functional group-containing fluorine-containing polymer, carbon black, a dispersant, and an organic solvent, and the dispersant has a base number of 12 mgKOH / g or more and an acid value of 12 mgKOH / g. It is a coating composition characterized by being g or less.
The dispersant preferably has a base number of 12 to 40 mg KOH / g and an acid value of 12 mg KOH / g or less.
The dispersant preferably has a base number of 12 to 40 mg KOH / g and an acid value of substantially 0 mg KOH / g.
The dispersant is preferably made of a polyurethane compound.
The polyurethane compound is preferably a polyurethane compound having an ethylene oxide chain and / or a propylene oxide chain in the main chain and having an amino group quaternized by a quaternizing agent.
The curable functional group-containing fluorine-containing polymer includes a polymer unit based on a fluorine-containing monomer, a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an acid anhydride monomer, an amino group-containing monomer, and And a polymerized unit based on at least one curable functional group-containing monomer selected from the group consisting of silicone-based vinyl monomers.
The fluorine-containing monomer is preferably at least one selected from the group consisting of tetrafluoroethylene, chlorotrifluoroethylene, and vinylidene fluoride.
The fluorine-containing monomer is preferably tetrafluoroethylene.
The present invention also includes a base material and a fluororesin layer on at least one surface of the base material, and the fluororesin layer is a cured coating film formed using the above-described coating composition. It is also the back sheet of the solar cell module that is characterized.
The present invention is also a solar cell module comprising the back sheet of the solar cell module described above.
The present invention is described in detail below.

The coating composition of the present invention is capable of forming a coating film that is excellent in pigment dispersibility and coating liquid stability and excellent in ultraviolet shielding properties.

FIG. 1 is a schematic diagram of an example of the solar cell module of the present invention. FIG. 2 is a schematic diagram of an example of the solar cell module of the present invention.

The present invention includes a curable functional group-containing fluorine-containing polymer, carbon black, a dispersant, and an organic solvent, and the dispersant has a base number of 12 mgKOH / g or more and an acid value of 12 mgKOH / g or less. It is the coating composition characterized by being.
For this reason, the coating composition of the present invention is excellent in pigment dispersibility and coating liquid stability. Moreover, the cured coating film obtained using the coating composition of this invention is excellent in ultraviolet-shielding property.

The dispersant contained in the coating composition of the present invention has a base number of 12 mgKOH / g or more.
When the base number is less than 12 mgKOH / g, the dispersion stability of carbon black is lowered.
The base number is preferably 14 mgKOH / g or more.
The base number is preferably 40 mgKOH / g or less, more preferably 35 mgKOH / g or less.
The base number can be measured by an acid-base titration method using an acidic substance.

The dispersant contained in the coating composition of the present invention has an acid value of 12 mgKOH / g or less.
When the acid value exceeds 12 mgKOH / g, liquid separation of the coating composition occurs.
The acid value is preferably 10 mgKOH / g or less, and more preferably substantially 0 mgKOH / g. The acid value substantially 0 mgKOH / g means specifically less than 0.1 mgKOH / g.
The acid value can be measured by an acid-base titration method using a basic substance.

The dispersant contained in the coating composition of the present invention preferably has a base.
As said base, an amino group etc. are mentioned, for example.
Examples of the amino group include —NH ₂ , —NHR, and —NRR ′. Also included are quaternized ones.

Although the said dispersing agent will not be specifically limited if it has the said base number and acid value, It is preferable to consist of a polyurethane compound which has the said base number and acid value. The polyurethane compound is a polymer having a urethane bond (—CONH—).

The polyurethane compound is preferably a polyurethane compound having an ethylene oxide chain and / or a propylene oxide chain in the main chain and having an amino group quaternized by a quaternizing agent.

Examples of the quaternizing agent include organic acids, inorganic acids, and organic halides that form salts with tertiary amino groups. Examples of the organic acid include formic acid, acetic acid, propionic acid, butyric acid, lactic acid, malic acid, malonic acid, adipic acid, and benzenesulfonic acid. Examples of the inorganic acid include hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid. In addition, as the organic halide, alkyl halides such as benzyl chloride and methyl chloride can be used. Furthermore, sulfate esters such as dimethyl sulfate and diethyl sulfate can also be used. Among them, a quaternizing agent using a sulfate ester as a tertiary amino group and a quaternary ammonium salt as a quaternary ammonium salt is preferable, and a dimethyl sulfate as a tertiary amino group as a quaternary ammonium salt is more preferable.

The quaternized amino group (quaternized amino group) is — [NRR′R ″] ⁺ X ⁻ (wherein R, R ′ and R ″ are hydrocarbon groups and may be the same And X ⁻ is a counter ion such as a halogen group).

In the above dispersant, the ethylene oxide chain and the propylene oxide chain are preferably in a mass ratio, and the ethylene oxide chain: propylene oxide chain is preferably 0.1: 99.9 to 15:85.

As the polyurethane compound, a polyurethane compound in which a polyol having an ethylene oxide chain and a propylene oxide chain, a polyisocyanate, and an amine compound capable of reacting with an isocyanate group are reacted, and an amino group is quaternized using the quaternizing agent. Etc. Specifically, for example, a polyol having an ethylene oxide chain and a propylene oxide chain is reacted with a polyisocyanate, then an amine compound capable of reacting with an isocyanate group is reacted, and an amino group (tertiary amino group) of the obtained compound is further reacted. And the like (quaternary ammonium salts) and the like which are quaternized with the above quaternizing agent.

The polyol having an ethylene oxide (EO) chain and a propylene oxide (PO) chain is not particularly limited as long as it is a polyol having an EO chain and a PO chain. For example, OH— (CH ₂ CH ₂ O) ₁ — ( A block copolymer represented by CH (CH ₃ ) —CH ₂ O) _m — (CH ₂ CH ₂ O) _n —H (l, m, and n are integers of 1 or more), and the like. .

As said polyisocyanate, diisocyanate is preferable. Examples of the diisocyanate include aliphatic diisocyanates such as ethylene diisocyanate, propylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; cycloaliphatic such as isophorone diisocyanate, 4-4'-dicyclohexylmethane diisocyanate, and norbornane diisocyanate. Examples thereof include aromatic diisocyanates such as diisocyanate, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, xylene diisocyanate, and 1,5-naphthalene diisocyanate.

Examples of the amine compound capable of reacting with the isocyanate group include butyldiethanolamine, ethyldiethanolamine, methyldiethanolamine, 2-dimethylaminoethanol, 2-diethylaminoethanol, 3-dimethylaminopropanol, Examples thereof include dimethylaminoethylamine, diethylaminoethylamine, dimethylaminopropylamine, diethylaminopropylamine, dibutylaminopropylamine and the like.

The dispersant is preferably a branched polymer, and more preferably a comb polymer.

The dispersant preferably has a weight average molecular weight of 10,000 to 100,000. If it is less than 10,000, there is a risk of poor dispersion stability or bleeding out. If it exceeds 100,000, there is a risk of poor dispersibility.
The weight average molecular weight is more preferably 20000 or more, further preferably 40000 or more, more preferably 70000 or less, and still more preferably 60000 or less.
The weight average molecular weight can be measured by gel permeation chromatography (GPC) (polystyrene conversion).

A commercially available product may be used as the dispersant. As a commercial item applicable to the coating composition of the present invention, for example, SOLPERSE 76500 (manufactured by Nippon Lubrizol Co., Ltd.) and the like can be mentioned.

It is preferable that content of the said dispersing agent in the coating composition of this invention is 2.5-40 mass parts with respect to 100 mass parts of carbon black.
If the amount is less than 2.5 parts by mass, the dispersion stability of carbon black may not be obtained. If it exceeds 40 parts by mass, the physical properties of the coating film may be reduced.
As for content of the said dispersing agent, 5 mass parts or more are more preferable, 9 mass parts or more are further more preferable, 35 mass parts or less are more preferable, and 30 mass parts or less are still more preferable.

The coating composition of the present invention contains a curable functional group-containing fluorine-containing polymer. By including the curable functional group-containing fluorine-containing polymer, a coating film excellent in weather resistance, moisture resistance, heat resistance and insulation can be formed.

As said curable functional group containing fluorine-containing polymer, the polymer which introduce | transduced the curable functional group into the fluorine-containing polymer is mentioned. The fluorine-containing polymer includes a resinous polymer having a clear melting point, an elastomeric polymer exhibiting rubber elasticity, and an intermediate thermoplastic elastomeric polymer.

Examples of the functional group that imparts curability to the fluorine-containing polymer include, for example, a hydroxyl group (excluding a hydroxyl group contained in a carboxyl group; the same shall apply hereinafter), a carboxyl group, a group represented by —COOCO—, an amino group, and glycidyl. Group, silyl group, silanate group, isocyanate group, and the like, and are appropriately selected in accordance with the ease of production of the polymer and the curing system. Among these, a hydroxyl group, a carboxyl group, a group represented by —COOCO—, an amino group, and a silyl group are preferable from the viewpoint of good curing reactivity, and particularly a hydroxyl group from the viewpoint of easy availability of the polymer and good reactivity. Is preferred. These curable functional groups are usually introduced into the fluorinated polymer by copolymerizing a fluorinated monomer and a curable functional group-containing monomer.

Examples of the curable functional group-containing monomer include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an acid anhydride monomer, an amino group-containing monomer, and a silicone vinyl monomer. 1 type, or 2 or more types of these can be used.
The curable functional group-containing fluorine-containing polymer includes a polymer unit based on a fluorine-containing monomer, a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an acid anhydride monomer, an amino group-containing monomer, and And a polymer unit based on at least one curable functional group-containing monomer selected from the group consisting of silicone vinyl monomers.

Examples of the curable functional group-containing monomer include, but are not limited to, the following. In addition, these 1 type (s) or 2 or more types can be used.

(1-1) Hydroxyl group-containing monomer:
Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxy-2- Hydroxyl-containing vinyl ethers such as methylbutyl vinyl ether, 5-hydroxypentyl vinyl ether and 6-hydroxyhexyl vinyl ether; hydroxyl-containing allyl ethers such as 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether and glycerol monoallyl ether It is done. Among these, hydroxyl group-containing vinyl ethers, particularly 4-hydroxybutyl vinyl ether and 2-hydroxyethyl vinyl ether, are preferable in that they have excellent polymerization reactivity and functional group curability.

Examples of other hydroxyl group-containing monomers include hydroxyalkyl esters of (meth) acrylic acid such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate.
In addition, the carboxyl group-containing monomer described later is not included in the hydroxyl group-containing monomer.

(1-2) Carboxyl group-containing monomer:
Examples of the carboxyl group-containing monomer include the general formula (1):

(Wherein R ¹ , R ² and R ³ are the same or different and all are hydrogen atoms, alkyl groups, aryl groups, carboxyl groups or alkoxycarbonyl groups; n is 0 or 1) Unsaturated carboxylic acids such as carboxylic acids, unsaturated dicarboxylic acids, monoesters thereof; or general formula (2):

(Wherein R ⁴ and R ⁵ are the same or different and both are saturated or unsaturated linear or cyclic alkyl groups; n is 0 or 1; m is 0 or 1) And monomers.

Specific examples of the unsaturated carboxylic acids represented by the general formula (1) include, for example, acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid, cinnamic acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid A monoester, fumaric acid, a fumaric acid monoester, etc. are mentioned. Among them, crotonic acid, itaconic acid, maleic acid, maleic acid monoester, fumaric acid, and fumaric acid monoester having low homopolymerization are preferable because homopolymers are low and it is difficult to form a homopolymer.

Specific examples of the carboxyl group-containing vinyl ether monomer represented by the general formula (2) include 3-allyloxypropionic acid, 3- (2-allyloxyethoxycarbonyl) propionic acid, 3- (2- Examples thereof include one or more of aryloxybutoxycarbonyl) propionic acid, 3- (2-vinyloxyethoxycarbonyl) propionic acid, 3- (2-vinyloxybutoxycarbonyl) propionic acid and the like. Among these, 3- (2-allyloxyethoxycarbonyl) propionic acid and the like are advantageous and preferable in terms of good monomer stability and polymerization reactivity.

As the carboxyl group-containing monomer, in addition to those represented by the general formula (1) or (2), for example, alkenyl esters of polybasic carboxylic acids such as vinyl phthalate and vinyl pyromellitic acid Can be used.

(1-3) Acid anhydride monomer:
Examples of the acid anhydride monomer include unsaturated dicarboxylic acid anhydrides such as maleic acid anhydride.

(1-4) Amino group-containing monomer:
Examples of the amino group-containing monomer include amino vinyl ethers represented by CH ₂ ═CH—O— (CH ₂ ) _x —NH ₂ (x = 0 to 10); CH ₂ ═CH—O—CO (CH ₂ ) amines represented by _{x -NH 2 (x = 1~10)} ; other aminomethylstyrene, vinylamine, acrylamide, vinylacetamide, vinylformamide or the like.

(1-5) Silicone vinyl monomer:
Examples of the silicone-based vinyl monomer include CH ₂ ═CHCO ₂ (CH ₂ ) ₃ Si (OCH ₃ ) ₃ , CH ₂ ═CHCO ₂ (CH ₂ ) ₃ Si (OC ₂ H ₅ ) ₃ , and CH ₂ ═C. _{(CH 3) CO 2 (CH} 2) 3 Si (OCH 3) 3, CH 2 = C (CH 3) CO 2 (CH 2) 3 Si (OC 2 H 5) 3, CH 2 = CHCO 2 (CH 2 _{) 3 SiCH 3 (OC 2 H} 5) 2, CH 2 = C (CH 3) CO 2 (CH 2) 3 SiC 2 H 5 (OCH 3) 2, CH 2 = C (CH 3) CO 2 (CH 2 ) ₃ Si (CH ₃ ) ₂ (OC ₂ H ₅ ), CH ₂ ═C (CH ₃ ) CO ₂ (CH ₂ ) ₃ Si (CH ₃ ) ₂ OH, CH ₂ ═CH (CH ₂ ) ₃ Si (OCOCH) _{3) 3, CH 2 = C} (C _{3) CO 2 (CH 2)} 3 SiC 2 H 5 (OCOCH 3) 2, CH 2 = C (CH 3) CO 2 (CH 2) 3 SiCH 3 (N (CH 3) COCH 3) 2, CH 2 = _{CHCO 2 (CH 2) 3 SiCH} 3 _{[ON (CH 3) C 2 H} 5 ] _{2, CH 2 = C (CH} 3) CO 2 (CH 2) 3 SiC 6 H 5 _[ON (CH _{3) C} 2 H _{5] 2,} etc. (meth) acrylic acid _{esters; CH 2 = CHSi [ON =} C (CH 3) (C 2 H 5)] 3, CH 2 = CHSi (OCH 3) 3, CH 2 = CHSi (OC ₂ H ₅ ) ₃ , CH ₂ = CHSiCH ₃ (OCH ₃ ) ₂ , CH ₂ = CHSi (OCOCH ₃ ) ₃ , CH ₂ = CHSi (CH ₃ ) ₂ (OC ₂ H ₅ ), CH ₂ = CHSi (CH ₃ ) _{2 iCH 3 (OCH 3) 2,} CH 2 = CHSiC 2 H 5 (OCOCH 3) 2, CH 2 = CHSiCH 3 _{[ON (CH 3) C 2 H} 5 ] _2, vinyl trichlorosilane or their partial hydrolysates And vinyl silanes such as trimethoxysilylethyl vinyl ether, triethoxysilylethyl vinyl ether, trimethoxysilylbutyl vinyl ether, methyldimethoxysilylethyl vinyl ether, trimethoxysilylpropyl vinyl ether, and triethoxysilylpropyl vinyl ether.

As the fluorine-containing monomer, that is, a monomer for forming a fluorine-containing polymer into which a curable functional group is introduced, for example, tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride, vinyl fluoride, and , Fluorovinyl ether can be mentioned, and one or more of these can be used.
Among these, at least one selected from the group consisting of tetrafluoroethylene, chlorotrifluoroethylene, and vinylidene fluoride is preferable, and tetrafluoroethylene is more preferable.

Examples of the fluorine-containing polymer into which the curable functional group is introduced may include the following, depending on the polymer units constituting the polymer.

(1) Perfluoroolefin polymer mainly composed of perfluoroolefin units:
Specific examples include a homopolymer of tetrafluoroethylene (TFE), a copolymer of TFE and hexafluoropropylene (HFP), perfluoro (alkyl vinyl ether) (PAVE), and the like, and further copolymerizable therewith. And copolymers with other monomers.

Examples of the other copolymerizable monomers include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl versatate, vinyl laurate, vinyl stearate, cyclohexyl carboxyl. Carboxylic acid vinyl esters such as vinyl acid vinyl, vinyl benzoate, para-t-butyl vinyl benzoate; alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether; ethylene, propylene, n-butene, isobutene, etc. Non-fluorinated olefins; fluorinated monomers such as vinylidene fluoride (VdF), chlorotrifluoroethylene (CTFE), vinyl fluoride (VF), fluorovinyl ether, etc. The present invention is not limited only to.

Among these, TFE-based polymers mainly composed of TFE are preferable in terms of excellent pigment dispersibility, weather resistance, copolymerization, and chemical resistance.

Specific examples of the curable functional group-containing perfluoroolefin-based polymer include, for example, a copolymer of TFE / isobutylene / hydroxybutyl vinyl ether / other monomers, TFE / vinyl versatate / hydroxybutyl vinyl ether / other monomers. Copolymer, TFE / VdF / hydroxybutyl vinyl ether / other monomer copolymer, etc., especially TFE / isobutylene / hydroxybutyl vinyl ether / other monomer copolymer, TFE / versaic acid Vinyl / hydroxybutyl vinyl ether / copolymers of other monomers are preferred.

Examples of the TFE-based curable polymer composition for paint include Zeffle GK series manufactured by Daikin Industries, Ltd.

(2) CTFE polymer mainly composed of chlorotrifluoroethylene (CTFE) unit:
Specific examples include a copolymer of CTFE / hydroxybutyl vinyl ether / other monomers.

Examples of the CTFE-based curable polymer composition for paint include Lumiflon manufactured by Asahi Glass Co., Ltd., Fluoronate manufactured by DIC Co., Ltd., Cefral Coat manufactured by Central Glass Co., Ltd., and ZAFLON manufactured by Toa Gosei Co., Ltd. it can.

(3) VdF polymers mainly composed of vinylidene fluoride (VdF) units:
Specific examples include VdF / TFE / hydroxybutyl vinyl ether / a copolymer of other monomers.

(4) Fluoroalkyl group-containing polymer mainly composed of fluoroalkyl units:
Specific examples include CF ₃ CF ₂ (CF ₂ CF ₂ ) _n CH ₂ CH ₂ OCOCH═CH ₂ (mixture of n = 3 and 4) / 2-hydroxyethyl methacrylate / stearyl acrylate copolymer. .

Examples of the fluoroalkyl group-containing polymer include Unidyne and Ftone manufactured by Daikin Industries, Ltd., and Zonyl manufactured by DuPont.

Among these, in consideration of weather resistance and moisture resistance, perfluoroolefin-based polymers are preferable.

The said curable functional group containing fluorine-containing polymer can be manufactured by the method disclosed by Unexamined-Japanese-Patent No. 2004-204205, for example.

It is preferable that content of the said curable functional group containing fluorine-containing polymer in the coating composition of this invention is 20-90 mass% with respect to 100 mass% of total amounts of the non volatile matter in a coating composition.

The coating composition of the present invention contains carbon black.
The carbon black is not particularly limited and includes generally known ones.
The carbon black preferably has an average particle diameter of 10 to 150 nm, more preferably 20 to 100 nm, from the viewpoint of the ultraviolet shielding effect.
The average particle diameter is a value obtained by observation with an electron microscope.

The average particle size of the carbon black after the dispersion step in the coating composition is preferably 50 to 1000 nm, more preferably 100 to 700 nm, and even more preferably 100 to 500 nm in view of the ultraviolet shielding effect.
The average particle diameter is a value obtained by measurement with a laser diffraction / scattering particle size distribution analyzer.

The content of carbon black is preferably 0.5 to 80 parts by mass with respect to 100 parts by mass of the curable functional group-containing fluorine-containing polymer in the coating composition. When the content of carbon black is within the above range, it can be well dispersed in the paint.
The content of carbon black is more preferably 3 parts by mass or more, more preferably 10 parts by mass or more, more preferably 60 parts by mass or less, and more preferably 50 parts by mass or less with respect to 100 parts by mass of the curable functional group-containing fluoropolymer. Further preferred.

The coating composition of the present invention contains an organic solvent.
Examples of the organic solvent include esters such as ethyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, cellosolve acetate, and propylene glycol methyl ether acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; tetrahydrofuran, dioxane Cyclic ethers such as N; N-dimethylformamide, amides such as N, N-dimethylacetamide; aromatic hydrocarbons such as xylene, toluene and solvent naphtha; glycol ethers such as propylene glycol methyl ether and ethyl cellosolve Diethylene glycol esters such as carbitol acetate; n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-do Kang, aliphatic hydrocarbons such as mineral spirits; these mixtures, and the like.
These may be used alone or in combination of two or more.
Of these, esters are preferable, and butyl acetate is preferable.

The coating composition of the present invention preferably further contains a curing agent. By containing a curing agent, a cured coating film can be formed using the coating composition of the present invention.
The curing agent is selected according to the functional group of the curable polymer. For example, for a hydroxyl group-containing fluoropolymer, an isocyanate curing agent, a melamine resin, a silicate compound, an isocyanate group-containing silane compound can be preferably exemplified. . In addition, amino-based curing agents and epoxy-based curing agents are used for carboxyl group-containing fluorine-containing polymers, and carbonyl-group-containing curing agents, epoxy-based curing agents, acid anhydride-based curing agents are used for amino group-containing fluorine-containing polymers. Is usually adopted.

As the curing agent, among them, a polyisocyanate compound derived from at least one isocyanate selected from the group consisting of xylylene diisocyanate (XDI) and bis (isocyanate methyl) cyclohexane (hydrogenated XDI, H6XDI), hexamethylene At least one compound selected from the group consisting of blocked isocyanate compounds based on diisocyanate (HDI), polyisocyanate compounds derived from hexamethylene diisocyanate (HDI), and polyisocyanate compounds derived from isophorone diisocyanate (IPDI) Is preferred.

The curing agent is derived from at least one isocyanate selected from the group consisting of xylylene diisocyanate (XDI) and bis (isocyanatomethyl) cyclohexane (hydrogenated XDI, H6XDI) (hereinafter also referred to as isocyanate (i)). When the polyisocyanate compound (hereinafter also referred to as polyisocyanate compound (I)) is used, the adhesion between the cured coating film obtained from the coating composition of the present invention and the encapsulant of the solar cell module is more excellent. It becomes a thing. Furthermore, the back sheet of the solar cell module having the cured coating film is more excellent in blocking resistance to the surface with which the cured coating film comes into contact in a winding process or the like.
Examples of the polyisocyanate compound (I) include an adduct obtained by addition polymerization of the isocyanate (i) and a trihydric or higher aliphatic polyhydric alcohol, and an isocyanurate structure (nurate) comprising the isocyanate (i). And a biuret composed of the above-mentioned isocyanate (i).

As the adduct, for example, the following general formula (3):

(In the formula, R ⁶ represents an aliphatic hydrocarbon group having 3 to 20 carbon atoms. R ⁷ represents a phenylene group or a cyclohexylene group. K is an integer of 3 to 20). Those having the following structure are preferred.
R ⁶ in the general formula (3) is a hydrocarbon group based on the trivalent or higher aliphatic polyhydric alcohol, more preferably an aliphatic hydrocarbon group having 3 to 10 carbon atoms, and 3 to 6 carbon atoms. The aliphatic hydrocarbon group is more preferable.
When R ⁷ is a phenylene group, a 1,2-phenylene group (o-phenylene group), a 1,3-phenylene group (m-phenylene group), and a 1,4-phenylene group (p-phenylene group) Any of these may be used. Of these, a 1,3-phenylene group (m-phenylene group) is preferable. Moreover, all R < ⁷ > in the said General formula (3) may be the same phenylene group, and 2 or more types may be mixed.
When R ⁷ is a cyclohexylene group, it may be any of 1,2-cyclohexylene group, 1,3-cyclohexylene group, and 1,4-cyclohexylene group. Of these, a 1,3-cyclohexylene group is preferable. Moreover, all R < ⁷ > in the said General formula (3) may be the same cyclohexylene group, and 2 or more types may be mixed.
The k is a number corresponding to the valence of a trihydric or higher aliphatic polyhydric alcohol. As said k, More preferably, it is an integer of 3-10, More preferably, it is an integer of 3-6.

The isocyanurate structure has the following general formula (4) in the molecule:

It has 1 or 2 or more isocyanurate rings.
Examples of the isocyanurate structure include a trimer obtained by the trimerization reaction of the isocyanate, a pentamer obtained by the pentamerization reaction, and a heptamer obtained by the heptamization reaction.
Among them, the following general formula (5):

(Wherein, R ⁷ is the same as R ⁷ in the general formula (3)). That is, the isocyanurate structure is preferably a trimer of at least one isocyanate selected from the group consisting of xylylene diisocyanate and bis (isocyanatomethyl) cyclohexane.

The biuret is represented by the following general formula (6):

(Wherein, R ⁷ is the formula (3) is the same as R ⁷ in.) Is a compound having a structure represented by, under different conditions than the case of obtaining the isocyanurate structure, It can be obtained by trimerizing the isocyanate.

The polyisocyanate compound (I) includes, among others, at least one isocyanate selected from the group consisting of the above adducts, that is, xylylene diisocyanate and bis (isocyanatomethyl) cyclohexane, and a trihydric or higher aliphatic polyhydric alcohol. Are preferably obtained by addition polymerization.

When the polyisocyanate compound (I) is an adduct of the isocyanate (i) and a trihydric or higher aliphatic polyhydric alcohol, the trihydric or higher aliphatic polyhydric alcohol is specifically glycerol. , Trimethylolpropane (TMP), 1,2,6-hexanetriol, trimethylolethane, 2,4-dihydroxy-3-hydroxymethylpentane, 1,1,1-tris (bishydroxymethyl) propane, 2,2 -Trihydric alcohols such as bis (hydroxymethyl) butanol-3; tetrahydric alcohols such as pentaerythritol and diglycerol; pentahydric alcohols such as arabit, ribitol, and xylitol (pentit); sorbitol, mannitol, galactitol, allozulcit, etc. Such as hexahydric alcohol (hexit) That. Of these, trimethylolpropane and pentaerythritol are particularly preferable.

Moreover, as xylylene diisocyanate (XDI) used as a component of the adduct, 1,3-xylylene diisocyanate (m-xylylene diisocyanate), 1,2-xylylene diisocyanate (o-xylylene diisocyanate), 1 1,4-xylylene diisocyanate (p-xylylene diisocyanate), among which 1,3-xylylene diisocyanate (m-xylylene diisocyanate) is preferable.

The bis (isocyanatemethyl) cyclohexane (hydrogenated XDI, H6XDI) used as a component of the adduct is 1,3-bis (isocyanatemethyl) cyclohexane, 1,2-bis (isocyanatemethyl) cyclohexane, 1, 4-bis (isocyanatomethyl) cyclohexane can be mentioned, among which 1,3-bis (isocyanatemethyl) cyclohexane is preferred.

Suitable in the present invention by addition polymerization of at least one isocyanate selected from the group consisting of xylylene diisocyanate and bis (isocyanatomethyl) cyclohexane and an aliphatic polyhydric alcohol having 3 or more valences as described above. Adducts used in the above are obtained.

As an adduct preferably used in the present invention, specifically, for example, the following general formula (7):

(Wherein R ⁸ represents a phenylene group or a cyclohexylene group), that is, at least one isocyanate selected from the group consisting of xylylene diisocyanate and bis (isocyanatomethyl) cyclohexane; Mention may be made of polyisocyanate compounds obtained by addition polymerization of methylolpropane (TMP).
The phenylene group or cyclohexylene group represented by R ⁸ in the general formula (7) is as described for R ⁷ in the general formula (3).

Commercially available products of the polyisocyanate compound represented by the general formula (7) include Takenate D110N (manufactured by Mitsui Chemicals, XDI and TMP adduct, NCO content 11.8%), Takenate D120N (Mitsui Chemicals) The product made from a company, the adduct of H6XDI and TMP, NCO content 11.0%), etc. are mentioned.

Specific examples of the polyisocyanate compound (I) having an isocyanurate structure include Takenate D121N (Mitsui Chemicals, H6XDI Nurate, NCO content 14.0%), Takenate D127N (Mitsui Chemicals, Inc.) H6XDI nurate, H6XDI trimer, NCO content 13.5%) and the like.

By using a blocked isocyanate based on hexamethylene diisocyanate (HDI) as a curing agent (hereinafter also simply referred to as a blocked isocyanate), the coating composition of the present invention has a sufficient pot life (pot life). .
As the blocked isocyanate, those obtained by reacting a polyisocyanate compound derived from hexamethylene diisocyanate (hereinafter also referred to as polyisocyanate compound (II)) with a blocking agent are preferable.
As the polyisocyanate compound (II), for example, an adduct obtained by addition polymerization of hexamethylene diisocyanate and a trihydric or higher aliphatic polyhydric alcohol, an isocyanurate structure (nurate structure) composed of hexamethylene diisocyanate, And biuret which consists of hexamethylene diisocyanate can be mentioned.

Examples of the adduct include the following general formula (8):

(Wherein R ⁹ represents an aliphatic hydrocarbon group having 3 to 20 carbon atoms. K is an integer of 3 to 20).
R ⁹ in the general formula (8) is a hydrocarbon group based on the above trivalent or higher aliphatic polyhydric alcohol, more preferably an aliphatic hydrocarbon group having 3 to 10 carbon atoms, and 3 to 6 carbon atoms. The aliphatic hydrocarbon group is more preferable.
The k is a number corresponding to the valence of a trihydric or higher aliphatic polyhydric alcohol. As said k, More preferably, it is an integer of 3-10, More preferably, it is an integer of 3-6.

The isocyanurate structure has the following general formula (4) in the molecule:

It has 1 or 2 or more isocyanurate rings.
Examples of the isocyanurate structure include a trimer obtained by the trimerization reaction of the isocyanate, a pentamer obtained by the pentamerization reaction, and a heptamer obtained by the heptamization reaction.
Among them, the following general formula (9):

The trimer represented by these is preferable.

The biuret is represented by the following general formula (10):

And can be obtained by trimerizing hexamethylene diisocyanate under conditions different from those for obtaining the isocyanurate structure.

As the blocking agent, a compound having active hydrogen is preferably used. As the compound having active hydrogen, for example, at least one selected from the group consisting of alcohols, oximes, lactams, active methylene compounds, and pyrazole compounds is preferably used.

Thus, the blocked isocyanate is obtained by reacting a polyisocyanate compound derived from hexamethylene diisocyanate with a blocking agent, and the blocking agent includes alcohols, oximes, lactams, and active methylene compounds. And at least one selected from the group consisting of pyrazole compounds is one of the preferred embodiments of the present invention.

When the polyisocyanate compound (II) for obtaining the blocked isocyanate is an adduct of hexamethylene diisocyanate and a trihydric or higher aliphatic polyhydric alcohol, the trihydric or higher aliphatic polyhydric alcohol is specifically Glycerol, trimethylolpropane (TMP), 1,2,6-hexanetriol, trimethylolethane, 2,4-dihydroxy-3-hydroxymethylpentane, 1,1,1-tris (bishydroxymethyl) propane , Trihydric alcohols such as 2,2-bis (hydroxymethyl) butanol-3; tetrahydric alcohols such as pentaerythritol and diglycerol; pentahydric alcohols such as arabit, ribitol and xylitol (pentit); Lactitol, allozulcit It includes hexavalent alcohols (hexites) or the like is. Of these, trimethylolpropane and pentaerythritol are particularly preferable.
The adduct is obtained by addition polymerization of hexamethylene diisocyanate and the above trivalent or higher aliphatic polyhydric alcohol.

Specific examples of the compound having active hydrogen to be reacted with the polyisocyanate compound (II) include alcohols such as methanol, ethanol, n-propanol, isopropanol, and methoxypropanol; acetone oxime, 2-butanone oxime, and cyclohexanone. Oximes such as oximes; lactams such as ε-caprolactam; active methylene compounds such as methyl acetoacetate and ethyl malonate; pyrazole compounds such as 3-methylpyrazole, 3,5-dimethylpyrazole, and 3,5-diethylpyrazole And one or more of these can be used.
Among these, active methylene compounds and oximes are preferable, and active methylene compounds are more preferable.

Commercially available block isocyanates include Duranate K6000 (manufactured by Asahi Kasei Chemicals Corporation, HDI active methylene compound block isocyanate), Duranate TPA-B80E (manufactured by Asahi Kasei Chemicals Corporation), Duranate MF-B60X (manufactured by Asahi Kasei Chemicals Corporation). , Duranate 17B-60PX (Asahi Kasei Chemicals Corporation), Coronate 2507 (Nippon Polyurethane Co., Ltd.), Coronate 2513 (Nippon Polyurethane Co., Ltd.), Coronate 2515 (Nippon Polyurethane Co., Ltd.), Sumijour BL-3175 (Sumi) Chemical Chemicals, Bayer Urethane Co., Ltd.), Luxate HC1170 (manufactured by Olin Chemicals), Luxate HC2170 (manufactured by Olin Chemicals), and the like.

As the curing agent, a polyisocyanate compound derived from hexamethylene diisocyanate (HDI) (hereinafter also referred to as polyisocyanate compound (III)) can be used. As polyisocyanate compound (III), what was mentioned above as polyisocyanate compound (II) is mentioned.

Specific examples of the polyisocyanate compound (III) include Coronate HX (manufactured by Nippon Polyurethane Co., Ltd., isocyanurate structure of hexamethylene diisocyanate, NCO content 21.1%), Sumijour N3300 (manufactured by Sumika Bayer, Hexamethylene diisocyanate isocyanurate structure), Takenate D170N (Mitsui Chemicals, hexamethylene diisocyanate isocyanurate structure), Sumidur N3800 (Sumika Bayer, hexamethylene diisocyanate isocyanurate structure prepolymer type) ) And the like.

A solar cell having a cured coating film obtained from the coating composition of the present invention by using, as a curing agent, a polyisocyanate compound derived from isophorone diisocyanate (IPDI) (hereinafter also referred to as polyisocyanate compound (IV)). The back sheet of the module has excellent blocking resistance to the surface with which the cured coating film comes into contact in the winding process or the like.

Examples of the polyisocyanate compound (IV) include an adduct obtained by addition polymerization of isophorone diisocyanate and a trihydric or higher aliphatic polyhydric alcohol, an isocyanurate structure (nurate structure) composed of isophorone diisocyanate, and Biuret made of isophorone diisocyanate can be mentioned.

Examples of the adduct include the following general formula (11):

(In the formula, R ¹⁰ represents an aliphatic hydrocarbon group having 3 to 20 carbon atoms. R ¹¹ represents the following general formula (12):

It is group represented by these. k is an integer of 3-20. ) Is preferred.
R ¹⁰ in the general formula (11) is a hydrocarbon group based on the above trivalent or higher aliphatic polyhydric alcohol, more preferably an aliphatic hydrocarbon group having 3 to 10 carbon atoms, and 3 to 6 carbon atoms. The aliphatic hydrocarbon group is more preferable.
The k is a number corresponding to the valence of a trihydric or higher aliphatic polyhydric alcohol. As said k, More preferably, it is an integer of 3-10, More preferably, it is an integer of 3-6.

The isocyanurate structure has the following general formula (4) in the molecule:

It has 1 or 2 or more isocyanurate rings.
Examples of the isocyanurate structure include a trimer obtained by a trimerization reaction of isophorone diisocyanate, a pentamer obtained by a pentamerization reaction, a heptamer obtained by a heptamerization reaction, and the like.
Among them, the following general formula (13):

(Wherein, R ¹¹ is the same as R ¹¹ in the general formula (11)). That is, the isocyanurate structure is preferably a trimer of isophorone diisocyanate.

The biuret is represented by the following general formula (14):

(Wherein, R ¹¹ is the formula (11) is the same as R ¹¹ in.) Is a compound having a structure represented by, under different conditions than the case of obtaining the isocyanurate structure, It can be obtained by trimerizing isophorone diisocyanate.

Above all, the polyisocyanate compound (IV) is preferably at least one selected from the group consisting of the adduct and the isocyanurate structure. That is, the polyisocyanate compound (IV) is selected from the group consisting of an adduct obtained by addition polymerization of isophorone diisocyanate and a trihydric or higher aliphatic polyhydric alcohol, and an isocyanurate structure composed of isophorone diisocyanate. It is preferable that it is at least one kind.

When the polyisocyanate compound (IV) is an adduct of isophorone diisocyanate and a trihydric or higher aliphatic polyhydric alcohol, specific examples of the trihydric or higher aliphatic polyhydric alcohol include glycerol and trimethylol. Propane (TMP), 1,2,6-hexanetriol, trimethylolethane, 2,4-dihydroxy-3-hydroxymethylpentane, 1,1,1-tris (bishydroxymethyl) propane, 2,2-bis ( Trivalent alcohols such as hydroxymethyl) butanol-3; tetravalent alcohols such as pentaerythritol and diglycerol; pentavalent alcohols such as arabit, ribitol and xylitol (pentit); hexavalents such as sorbit, mannitol, galactitol and allozulcit Alcohol (hexit) etc. It is. Of these, trimethylolpropane and pentaerythritol are particularly preferable.

Adducts suitably used in the present invention can be obtained by addition polymerization of isophorone diisocyanate and a trihydric or higher aliphatic polyhydric alcohol as described above.

As an adduct preferably used in the present invention, specifically, for example, the following general formula (15):

(In the formula, R ¹² represents the following general formula (12):

It is group represented by these. ), That is, a polyisocyanate compound obtained by addition polymerization of isophorone diisocyanate and trimethylolpropane (TMP).

As a commercial item of the polyisocyanate compound (TMP adduct of isophorone diisocyanate) represented by the general formula (12), Takenate D140N (manufactured by Mitsui Chemicals, Inc., NCO content 11%) and the like can be mentioned.

Examples of commercially available isocyanurate structures made of isophorone diisocyanate include Desmodur Z4470 (manufactured by Sumika Bayer Urethane Co., Ltd., NCO content 11%).

Among these, Takenate D120N (manufactured by Mitsui Chemicals, NCO content 11%) and Sumijour N3300 (manufactured by Sumika Bayer, isocyanurate structure of hexamethylene diisocyanate) are more preferable as the curing agent.

It is preferable that content of the hardening | curing agent in the coating composition of this invention is 0.1-5 equivalent with respect to 1 equivalent of curable functional groups in a curable functional group containing fluorine-containing polymer, 0.5-1 More preferably, it is 5 equivalents.

The coating composition of the present invention may further contain other components as necessary. Examples of other components include other resins and additives. Examples of the additives include a curing accelerator, an antifoaming agent, a leveling agent, an ultraviolet absorber, a light stabilizer, a thickener, and an adhesion improving agent. , Delustering agents, hydrophilizing agents, and the like.

Examples of the curing accelerator include organic tin compounds, acidic phosphate esters, reaction products of acidic phosphate esters and amines, saturated or unsaturated polycarboxylic acids or acid anhydrides thereof, organic titanate compounds, amine compounds, Examples include lead octylate.

1 type may be used for a hardening accelerator and it may use 2 or more types together. As for the compounding quantity of a hardening accelerator, about 1.0 * 10 ^{< -6} > -1.0 * 10 ^<-2 > mass part is preferable with respect to 100 mass parts of curable functional group containing fluorine-containing polymers, 5.0 * 10 <^-5> -. About 1.0 × 10 ⁻³ parts by mass is more preferable.

As the ultraviolet absorber, both organic and inorganic ultraviolet absorbers can be used. Examples of the organic compound type include salicylic acid ester type, benzotriazole type, benzophenone type, cyanoacrylate type and other ultraviolet absorbers, and inorganic type is preferably a filler type inorganic ultraviolet absorber such as zinc oxide and cerium oxide. .

Examples of the hydrophilizing agent include those that are unevenly distributed on the surface of the cured coating film and can retain a hydroxyl group, and specifically include GH-701 manufactured by Daikin Industries, Ltd. As for the compounding quantity of a hydrophilizing agent, it is desirable that it is 0.01-50 mass% in the ratio with respect to the non volatile matter in a coating composition.

The coating composition of the present invention can be prepared by mixing or dispersing the above-described curable functional group-containing fluorine-containing polymer, carbon black, a dispersant, and, if necessary, other components in an organic solvent. .
The mixing and dispersion are not particularly limited, and can be performed using a known apparatus such as a paint shaker, a bead mill, or a kneader.
The solid content concentration of the coating composition of the present invention is not particularly limited, and may be appropriately adjusted according to the method of use.

The method for forming a cured coating film using the coating composition of the present invention is not particularly limited, but usually, the coating composition of the present invention containing a curing agent is applied onto a substrate and cured. Form a cured coating.
The said coating is not specifically limited, What is necessary is just to use a well-known method, for example, a roll coat, a curtain coat, a spray coat, a die coat, a gravure coat etc. are mentioned.
The curing may be appropriately selected from drying, heating, radiation irradiation, or the like according to the components of the coating composition.

Thus, the coating composition of the present invention contains a specific dispersant. For this reason, it is excellent in pigment dispersibility and coating liquid stability. Moreover, the cured coating film excellent in ultraviolet-ray shielding can be formed using the coating composition of this invention. For this reason, the coating composition of this invention can be applied suitably as a coating agent for back sheets of a solar cell module.

A cured coating film can be formed using the coating composition of the present invention. By forming a cured coating film using the coating composition of the present invention on various resin base materials such as vinyl chloride, polycarbonate and acrylic resin, the flame retardancy and weather resistance of the resin base material can be improved. Further, a hydrophilic surface can be added.

The back sheet | seat of the solar cell module provided with the cured coating film formed using the coating composition of this invention is also one of this invention.
That is, the present invention also includes a base material and a fluororesin layer on at least one surface of the base material, and the fluororesin layer is formed of a cured coating film formed using the coating composition described above. It is also a back sheet of the solar cell module characterized by this.

The back sheet of the solar cell module of the present invention has a base material and a fluororesin layer on at least one surface of the base material.
As said base material, the resin sheet generally used for the back seat | sheet of a solar cell module is mentioned.
Examples of the resin sheet include polyethylene, polypropylene, polystyrene, polymethyl methacrylate, polytetrafluoroethylene, polyamide, polyacrylonitrile, polyvinyl chloride, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate ( PEN), polyoxymethylene, polycarbonate, polyphenylene oxide, polyester urethane, poly m-phenylene isophthalamide, and a sheet made of a polymer such as poly p-phenylene terephthalamide.
Of these, polyethylene terephthalate (PET) is preferable.

The substrate may also be a water impermeable sheet. By using a water-impermeable sheet, it is possible to prevent moisture from permeating through the sealing material and the solar battery cell when the back sheet of the present invention is used to form a solar battery module.
Examples of the water-impermeable sheet include PET sheets, silica-deposited PET sheets, and metal sheets such as aluminum and stainless steel.
Of these, a silica-deposited PET sheet and a PET sheet are preferable in that they are lightweight, inexpensive, and flexible.

Moreover, in order to improve adhesiveness with the fluororesin layer on the said base material or another layer, a sheet | seat, etc., the said base material may be what surface-treated. Examples of the surface treatment include corona discharge treatment, plasma discharge treatment, chemical conversion treatment, and blast treatment in the case of a metal sheet. Any processing may adopt a conventionally known method.
The surface treatment may be formed on one surface of the base material or may be formed on both surfaces.

The substrate preferably has a thickness of 10 to 500 μm, and more preferably 50 to 300 μm.

The back sheet of the solar cell module of the present invention has a fluororesin layer on at least one surface on the substrate. The said fluororesin layer is a cured coating film formed using the coating composition of this invention mentioned above.
The fluororesin layer can be formed in the same manner as the method for forming a cured coating film using the coating composition of the present invention described above.
The coating on the substrate may be performed by directly applying the coating composition to the substrate, or may be performed by applying it through a primer layer or the like.
The primer layer may be formed by a conventional method using a conventionally known primer coating. Examples of the primer coating include epoxy resin, urethane resin, acrylic resin, silicone resin, polyester resin, and the like.

The film thickness of the fluororesin layer is preferably 2 μm or more from the viewpoint of good concealability, weather resistance, chemical resistance, and moisture resistance. More preferably, it is 3 micrometers or more, More preferably, it is 5 micrometers or more. The upper limit is preferably about 1000 μm, and more preferably 100 μm because if the thickness is too thick, the effect of reducing the weight cannot be obtained. As said film thickness, 5-40 micrometers is especially preferable.

The fluororesin layer preferably has a degree of cross-linking calculated from Soxhlet extraction with acetone as a gel fraction of 90 to 100%, more preferably 95 to 100%, and more preferably 98 to 100%. Further preferred.

The back sheet of the solar cell module of the present invention may also have the fluororesin layer on both surfaces of the substrate. In the case of having a fluororesin layer on both surfaces of the base material, these two fluororesin layers may be formed from the components included in the above-described range, and even if the fluororesin layer is composed of the same components, It may be a fluororesin layer made of different components.
Moreover, in order to improve adhesiveness with another layer, you may surface-treat to the said fluororesin layer.
Examples of the surface treatment include corona discharge treatment, plasma discharge treatment, chemical conversion treatment, and coating treatment such as a silane coupling agent.

The back sheet of the solar cell module of the present invention may have other material layers in addition to the base material and the fluororesin layer described above. When the said back sheet has another material layer, it is preferable to laminate | stack in order of another material layer, a base material, and a fluororesin layer.
Examples of the other material layers include an adhesive layer made of an adhesive, a cured coating film of a fluorine-containing polymer paint having no curable functional group, a fluorine-containing polymer sheet, a polyester sheet, or a coating film of a polyester paint (another sheet or Coating film). These layers may be laminated via a primer layer or the like.

Examples of the adhesive layer include known urethane adhesives, polyester adhesives, epoxy adhesives, nylon adhesives, ethylene-vinyl acetate adhesives, acrylic adhesives, rubber adhesives, and the like. Examples include a layer made of an adhesive.

As a cured coating film of the above-mentioned fluorine-containing polymer paint having no curable functional group, for example, a cured coating of a paint in which tetraalkoxysilane or a partial hydrolyzate thereof is blended with PVdF described in JP-A-2004-214342. Film, cured coating film of mixed paint of VdF / TFE / CTFE copolymer and alkoxysilane unit-containing acrylic resin, cured coating film of mixed paint of VdF / TFE / HFP copolymer and hydroxyl group-containing acrylic resin, VdF / Examples thereof include a cured coating film of a paint in which an aminosilane coupling agent is blended with an HFP copolymer. The film thickness is usually preferably 5 to 300 μm from the viewpoint of good concealability, weather resistance, chemical resistance, and moisture resistance. More preferably, it is 10-100 micrometers, More preferably, it is 10-50 micrometers.

Examples of the fluoropolymer sheet include a PVdF sheet, a PVF sheet, a PCTFE sheet, a TFE / HFP / ethylene copolymer sheet, a TFE / HFP copolymer (FEP) sheet, a TFE / PAVE copolymer (PFA) sheet, and ethylene. Examples thereof include fluorine-containing polymer sheets used in current backsheets such as a / TFE copolymer (ETFE) sheet and an ethylene / CTFE copolymer (ECTFE) sheet. The film thickness is usually preferably 5 to 300 μm from the viewpoint of good weather resistance. More preferably, it is 10-100 micrometers, More preferably, it is 10-50 micrometers.

As said polyester sheet, what is used with the conventional back sheet can be used as it is, and the adhesion to the water-impermeable sheet is acrylic adhesive, urethane adhesive, epoxy adhesive, polyester adhesive. Etc. The film thickness is usually preferably 5 to 300 μm from the viewpoint of good weather resistance, cost, and transparency. More preferably, it is 10-100 micrometers, More preferably, it is 10-50 micrometers.

Examples of the polyester paint include those using a saturated polyester resin using polyvalent carboxylic acid and polyhydric alcohol, and those using an unsaturated polyester resin using maleic anhydride, fumaric acid and the like and glycols, etc. A coating film can be formed by a coating method such as roll coating, curtain coating, spray coating, or die coating. The film thickness is preferably 5 to 300 μm from the viewpoint of good concealability, weather resistance, chemical resistance, and moisture resistance. More preferably, it is 10-100 micrometers, More preferably, it is 10-50 micrometers.

When the back sheet of the solar cell module of the present invention forms a fluororesin layer using the coating composition by the above-described method on the base material, forms the other material layer, or stacks the sheets. Good. Moreover, it is good to manufacture so that it may become a desired layer structure by a well-known method.

The present invention is also a solar cell module including the back sheet of the solar cell module described above.
The solar cell module of the present invention preferably has the above-described back sheet and a sealing material layer formed on the back sheet.
The encapsulant layer is a layer for encapsulating the solar battery cell, and is composed of ethylene / vinyl acetate copolymer (EVA), polyvinyl butyral (PVB), silicone resin, epoxy resin, acrylic resin, and the like. Is preferred. Of these, EVA is preferably used.

The schematic schematic diagram of an example of the preferable embodiment of the solar cell module of this invention is shown in FIG.1 and FIG.2.
In the first structure shown in FIG. 1, the solar battery cell 1 is sealed with a sealing material layer 2, and the sealing material layer 2 is sandwiched between a surface layer 3 and a back sheet 4. The back sheet 4 includes a base material 5 and a fluororesin layer 6, and is provided so that the fluororesin layer 6 is the outermost layer.

The surface layer 3 is a layer for protecting the light receiving surface of the solar cell module, and usually a glass plate is used, but a flexible material such as a resin sheet may be used.

In the second structure shown in FIG. 2, the back sheet 4 has a three-layer structure having the other material layer 7 on one surface of the substrate 5 and the fluororesin layer 6 on the other surface. The fluororesin layer 6 is provided as the outermost layer.

The solar cell module of the present invention may further have a junction box. The junction box is connected to electrodes and wiring for extracting output power from the solar cells (electrodes and wiring connected to the solar cells) and cables for extracting output power to the outside of the solar cell module. It is a box for storing terminals.
The junction box is preferably provided on the back sheet side surface of the solar cell module via an adhesive layer. The adhesive layer may be a layer made of a known adhesive.

As mentioned above, according to this invention, the coating composition which can form the cured coating film which has the outstanding ultraviolet-ray shielding can be provided. The cured coating film formed on the base material using the coating composition of the present invention can be suitably applied as a back sheet for a solar cell module.

The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1
92.7 parts by mass of butyl acetate, 13 parts by mass of MA100 (manufactured by Mitsubishi Chemical Corporation) as a pigment, and SOLPERSE 76500 (Nippon Lubrizol Co., Ltd.) as a dispersant with respect to 100 parts by mass of Zeffle GK-570 (manufactured by Daikin Industries) 6.5 parts by mass) was added to prepare a coating composition.

(Examples 2-6, Comparative Examples 1-4)
A coating composition was prepared in the same manner as in Example 1 except that pigment, dispersant, and butyl acetate were added as shown in Table 1 to 100 parts by mass of Zeffle GK-570 (manufactured by Daikin Industries, Ltd.). .

In addition, each component in Table 1 is as follows.
Curable functional group-containing fluorine-containing polymer:
Zeffle GK-570 (in butyl acetate, solid concentration 65% by mass, manufactured by Daikin Industries, Ltd.)
Pigment:
Raven420 (carbon black, average particle size: 86 nm, pH: 8.3, manufactured by COLUMBIAN)
MA100 (carbon black, average particle size: 24 nm, pH: 3.5, manufactured by Mitsubishi Chemical Corporation)
Dispersant:
SOLSPERSE 76500 (polyurethane compound having an amino group quaternized with an ethylene oxide (EO) chain, a propylene oxide (PO) chain and a quaternizing agent, a base number of 15.2 mg KOH / g, an acid value of substantially 0 mg KOH / g, weight average) (Molecular weight 50000, EO is 10% of PO, active mass 50% by mass, manufactured by Nippon Lubrizol)
Disparon DA-7301 (polyester acid amide amine salt, base number 40 mg KOH / g, acid value 15 mg KOH / g, weight average molecular weight 9700, active ingredient 75 mass%, manufactured by Enomoto Kasei Co., Ltd.)
Disparon DA-375 (polyether phosphate compound, base number 0 mg KOH / g, acid value 14 mg KOH / g, weight average molecular weight 2000 to 3000, active ingredient> 95% by mass, manufactured by Enomoto Kasei Co., Ltd.)

The following evaluation was performed about the obtained coating composition. The results are shown in Table 1.
<Pigment dispersibility>
A PCTFE film (manufactured by Daikin Industries, Ltd., NEOFLON PCTFE film, thickness 25 μm) is prepared as a base material for evaluation, and the coating compositions of Examples 1 to 6 and Comparative Examples 1 to 4 are provided on one side of this film. Was coated with a bar coater so that the dry film thickness was 10 μm, and dried at 60 ° C. for 30 minutes to obtain a 10 μm coated film.
Using a variable angle gloss meter (Nippon Denshoku Industries Co., Ltd., VGS-SENSOR), the glossiness of the obtained coating film was measured.

<Coating solution stability>
The coating compositions of Examples 1 to 6 and Comparative Examples 1 to 4 were put in a screw tube container having a volume of 50 ml, sealed, allowed to stand at 50 ° C., and the number of days after which no liquid separation was observed after standing. Evaluated.

<Ultraviolet shielding>
In the same manner as the above-described pigment dispersibility evaluation method, the coating compositions of Examples 1 to 6 and Comparative Examples 1 to 4 were applied to a PCTFE film with a bar coater so that the dry film thickness was 10 μm. The film was dried at 30 ° C. for 30 minutes to obtain a 10 μm coated film.
Using a spectrophotometer (U-4100, manufactured by Hitachi, Ltd.), the transmittance of ultraviolet light having a wavelength of 400 nm of the obtained coating film was measured.

ADVANTAGE OF THE INVENTION According to this invention, the coating composition which has the outstanding pigment dispersibility and coating-liquid stability, and the back sheet | seat of the solar cell module excellent in ultraviolet-ray shielding can be provided.

DESCRIPTION OF SYMBOLS 1 Solar cell 2 Sealing material layer 3 Surface layer 4 Back sheet 5 Base material 6 Fluororesin layer 7 Other material layers

Claims (8)

Including a curable functional group-containing fluorine-containing polymer, carbon black, a dispersant, and an organic solvent,
The dispersant, base number is 14 ~35mgKOH / g, and state, and are acid value 12 mgKOH / g or less,
The dispersant, coating composition characterized Rukoto a polyurethane compound. The coating composition according to claim 1, wherein the dispersant has a base number of 14 to 35 mgKOH / g and an acid value of substantially 0 mgKOH / g. The coating composition according to claim 1 or 2 , wherein the polyurethane compound is a polyurethane compound having an ethylene oxide chain and / or a propylene oxide chain in the main chain and having an amino group quaternized by a quaternizing agent. The curable functional group-containing fluorine-containing polymer is a polymer unit based on a fluorine-containing monomer, a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an acid anhydride monomer, an amino group-containing monomer, and claim 1, 2 or 3 Symbol placement of the coating composition comprising at least one polymerization unit based on curable functional group-containing monomer, a selected from the group consisting of silicone-based vinyl monomer. The coating composition according to claim 4 , wherein the fluorine-containing monomer is at least one selected from the group consisting of tetrafluoroethylene, chlorotrifluoroethylene, and vinylidene fluoride. The coating composition according to claim 4 , wherein the fluorine-containing monomer is tetrafluoroethylene. A base material, and a fluororesin layer on at least one surface of the base material;
The fluororesin layer, claims 1, 2, 3, 4, the backsheet of a solar cell module, which is a cured coating film formed by using a 5 or 6 Symbol mounting of the coating composition. A solar cell module comprising the back sheet of the solar cell module according to claim 7 .