JP2017110126A - Polyol composition for polyisocyanate-curable adhesive coating agent, adhesive coating agent, cured material thereof, adhesive sheet, and solar battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an adhesive coating agent that, when bonding an encapsulation material for solar battery cell with a substrate sheet, manifests excellent adhesive strength; a polyol composition for the coating agent; a cured material of the adhesive coating agent; an adhesive sheet obtained by applying the adhesive coating agent; and a solar battery module using the sheet.SOLUTION: Provided is a coating for a solar battery back sheet, represented by b in Figure 1, where, as a polyol composition for a two liquid-type urethane-based easy adhesive coating agent, there is used a composition containing as essential components a hydroxyl group-containing (meth)acryl resin (I) and a polyester polyol (II) having an unsaturated double bond and a carbodiimide group in a molecular structure.SELECTED DRAWING: Figure 1

Description

  The present invention is excellent in an adhesive coating agent excellent in adhesiveness between a solar cell sealing material and a substrate sheet, a polyol composition for the coating agent, a cured product of the adhesive coating agent, adhesive strength and heat-and-moisture resistance. The present invention relates to an adhesive sheet and a solar cell module using the sheet.

  In recent years, the depletion of fossil fuels such as oil and coal has been threatened, and there is an urgent need to develop alternative energy that can be obtained from these fossil fuels. Among such fossil fuel alternative energy, solar power generation capable of directly converting solar energy into electric energy is being put into practical use as a new energy source that is semi-permanent and non-polluting, and is actually used. The improvement in price / performance ratio is remarkable, and it is highly expected as a clean energy source.

  The solar cell used for photovoltaic power generation is the heart of a photovoltaic power generation system that directly converts sunlight energy into electrical energy, and is composed of semiconductors such as silicon, and its structure is a photovoltaic cell. Are connected in series and in parallel, and various packaging is applied to form a unit to protect the cells. A unit incorporated in such a package is called a solar cell module. In general, a light-receiving surface that is exposed to sunlight is covered with a surface protection member such as a glass plate, and a gap between the solar cell and the surface protection member is made of a thermoplastic resin. It has the structure which sealed and also arrange | positioned the back surface protection sheet.

  Since such a solar cell module is normally used outdoors for a long period of about 30 years, the material for sealing the solar cell and the surface protection member is highly transparent and moisture resistant. An excellent ethylene-vinyl acetate copolymer resin is often used, and the back protective sheet (back sheet) is made of a polyester sheet such as polyethylene terephthalate resin, and an adhesive is applied to both sides thereof. And then laminating a laminated sheet of fluorine resin sheets with excellent weather resistance, such as polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, polychlorotrifluoroethylene, and metal foil such as aluminum foil. Those having water vapor barrier performance are widely used.

  Thus, the laminated sheet provided with the fluororesin sheet is a back sheet having excellent weather resistance, but is expensive. In addition, although the back sheet has sufficient practical adhesive strength, a phenomenon in which the adhesive strength with time at the interface between the fluororesin sheet and the base sheet decreases due to long-term use in a humid heat environment is inevitable. However, it has not been able to sufficiently cope with higher long-term reliability and durability required in recent years. In addition, since an adhesive application process and a fluorine resin sheet lamination process are required, productivity and manufacturing cost have to be increased.

  Therefore, in recent years, instead of laminating the above-mentioned fluorine-based resin sheet on the surface of the back sheet that contacts the solar cell sealing material, means for applying an adhesive coating agent to the surface of the base material sheet on the sealing material side is Widely adopted.

  The back sheet using such an adhesive coating agent is unable to protect the solar cell from moisture and external factors when the base sheet of the back sheet is peeled off, and the output of the solar cell is deteriorated. Therefore, the adhesive coating agent layer is required to have high adhesion and adhesion durability. Therefore, the adhesive coating agent needs to ensure adhesion with a solar battery cell sealing material and at the same time, ensure adhesion with a substrate sheet such as a PET sheet.

  Therefore, conventionally, as an adhesive coating agent having excellent adhesion durability, for example, an acrylic polymer having an acryloyl group and a hydroxyl group obtained by reacting acrylic acid with a hydroxy group-containing acrylic oligomer and a polyisocyanate component are essential. A technique using a two-component adhesive coating agent as a component is known (see Patent Document 1 below).

  However, although the adhesive coating agent described in Patent Document 1 exhibits good adhesiveness, the shrinkage increases when the acryloyl group is crosslinked, and sufficient adhesion to a substrate sheet such as PET cannot be ensured. It was.

JP2013-136665A

  Therefore, the problem to be solved by the present invention is an adhesive coating agent that exhibits excellent adhesive strength when the solar cell sealing material and the substrate sheet are bonded, the polyol composition for the coating agent, An object of the present invention is to provide a cured product of an adhesive coating agent, an adhesive sheet obtained by applying the adhesive coating agent, and a solar cell module using the sheet.

  As a result of intensive studies to solve the above problems, the inventors of the present invention are mainly composed of a hydroxyl group-containing (meth) acrylic resin blended with a polyester polyol having an unsaturated double bond and a carbodiimide group in the molecular structure. A two-component curable adhesive coating agent using a polyisocyanate compound as a curing agent, while maintaining good adhesion to a substrate sheet such as a PET sheet, and sealing solar cells The present inventors have found that excellent adhesiveness with the material is expressed, and have completed the present invention.

  That is, the present invention comprises a polyisocyanate comprising, as essential components, a hydroxyl group-containing (meth) acrylic resin (I) and a polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure. The present invention relates to a polyol composition for a curable adhesive coating agent.

  The present invention further relates to an adhesive coating agent comprising the polyol composition (α) and the polyisocyanate compound (β) as essential components.

  The present invention further relates to a cured product obtained by curing the adhesive coating agent.

  The present invention further relates to an adhesive sheet in which an adhesive layer is formed by applying and curing the adhesive coating agent on a polyester base sheet.

  In the present invention, the solar cell (A), the surface protective substrate (B), the solar cell sealing material (D), and the back sheet (E) are essential components, and the back sheet (E ) Has an essential layer configuration of the base sheet (a) and the adhesive layer (b) that is a cured product of the adhesive coating agent formed on the base sheet (a), and The back sheet (E) is disposed such that the adhesive layer (b) is in contact with the solar cell sealing material (D).

  According to the present invention, an adhesive coating agent that exhibits excellent adhesive strength when the solar cell sealing material and the base sheet are adhered, the polyol composition for the coating agent, and curing of the adhesive coating agent Product, an adhesive sheet obtained by applying the adhesive coating agent, and a solar cell module using the sheet.

FIG. 1 is a cross-sectional view of an example of the solar cell module of the present invention.

  The polyol composition for a polyisocyanate curable adhesive coating agent of the present invention (hereinafter simply abbreviated as “polyol composition”) is used as a main component of an adhesive coating agent constituting a back sheet of a solar cell module. is there. In addition, the polyisocyanate compound mentioned later can be used as the hardening | curing agent. In addition, the adhesive coating agent is used not only for the back sheet of the solar cell module, but also as an adhesive coating agent when using a resin sheet as an alternative material for the surface protection glass of the solar cell module. it can.

  Here, the hydroxyl group-containing (meth) acrylic resin (I) constituting the polyol composition of the present invention essentially comprises a hydroxyl group-containing (meth) acrylate (a) and another (meth) acrylic monomer (b). Examples of the component include those obtained by copolymerization.

  Here, examples of the hydroxyl group-containing (meth) acrylate (a) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and polyethylene glycol mono (meth) ) Acrylate, polypropylene glycol mono (meth) acrylate, and the like.

  Moreover, as said other (meth) acryl monomer (b), C1-C3 alkyl groups, such as methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, etc. (Meth) acrylate (b-1) esterified with n-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meta ) Acrylate, isoamyl (meth) acrylate, neopentyl (meth) acrylate, n-hexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) ) Acrylate, n-nonyl (meth) acryl , Isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) ) Acrylate, hexadecyl (meth) acrylate, cyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate (meth) acrylate esterified with an alkyl group having 4 to 16 carbon atoms (b-2) And (meth) acrylic acid (b-3).

  In the present invention, as the other (meth) acrylic monomer (b), (meth) acrylate (b-2) esterified with an alkyl group having 4 to 16 carbon atoms is used as an essential monomer component. It is preferable from the viewpoint that adhesion to a substrate sheet such as PET is drastically improved, and adhesive strength and heat-and-moisture resistance are improved. Among such (meth) acrylates (b-2), cyclohexyl (meth) acrylate, isobutyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, among others And, (meth) acrylate selected from the group consisting of lauryl (meth) acrylate is preferable from the point that the effect of improving the adhesiveness with the base material sheet becomes remarkable.

  In the present invention, when producing the hydroxyl group-containing (meth) acrylic resin (I), the polarity of the adhesive coating agent itself is excellent in the adhesiveness to the base sheet depending on the composition ratio of each monomer component. It can be adjusted to the optimum range. From such a viewpoint, the hydroxyl group-containing (meth) acrylate (a), the (meth) acrylate (b-1) esterified with an alkyl group having 1 to 3 carbon atoms, and the alkyl having 4 to 16 carbon atoms (Meth) acrylate (b-2) esterified with a group as an essential monomer component, and the hydroxyl group-containing (meth) acrylate among the monomer components constituting the hydroxyl group-containing (meth) acrylic resin (I) The (meth) acrylate (b-1) esterified with an alkyl group having 3 to 20% by mass and 1 to 3 carbon atoms in (a) is 15 to 50% by mass and alkyl having 4 to 16 carbon atoms. It is preferable to use (meth) acrylate (b-2) esterified with a group in a proportion of 30 to 76% by mass. Moreover, when using (meth) acrylic acid (b-3), it is preferable to use in the ratio used as 0.1-5 mass% in a monomer component.

  Further, the hydroxyl group-containing acrylic resin (I) is an aromatic vinyl compound such as styrene and methylstyrene within a range not impairing the effects of the present invention in addition to the various monomers described above, for example, within a range of 3% by mass or less. May be used in combination as a raw material monomer.

  Examples of the hydroxyl group-containing acrylic resin (I) used in the present invention include the hydroxyl group-containing (meth) acrylate (a) and other (meth) acrylic monomers (b), benzoyl peroxide, azobisisobutyronitrile. 2,2′-azobis (2-methylbutyronitrile), t-butylperoxy-2-ethylhexanoate, 1,1-di (t-butylperoxy) cyclohexane, t-amylperoxy-2- It can be produced by a radical polymerization reaction using a radical polymerization initiator such as ethyl hexanoate, t-butyl peroctoate, di-t-butyl peroxide or t-butyl perbenzoate. In this case, these radical polymerization initiators may be used alone or in combination of two or more. Such radical polymerization reaction is usually carried out in the range of 60 to 150 ° C. in hydrocarbon solvents such as toluene, xylene, cyclohexane, n-hexane, and octane; methyl acetate, ethyl acetate, n-butyl acetate, isobutyl acetate. Ester solvents such as n-propyl acetate, amyl acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethoxyethyl propionate; ether solvents such as diethylene glycol dimethyl ether; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc. It is preferable to carry out in an organic solvent such as a ketone solvent, or in a mixed solvent of two or more thereof.

  The hydroxyl group-containing acrylic resin (I) thus obtained is preferably in the range of a hydroxyl value of 1 to 200 mgKOH / g from the viewpoint of adhesive strength and heat and humidity resistance, and its number average molecular weight (Mn) is 5 In the range of 1,000,000 to 500,000, the adhesive strength and the heat-and-moisture resistance are also favorable.

  Next, the polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure used in the polyol composition of the present invention is obtained by introducing an unsaturated double bond into the resin structure. High adhesiveness with a battery cell sealing material can be expressed. In addition, by introducing a carbodiimide group into the resin structure, the polyester polyol (II) can be firmly bonded to a substrate sheet such as a polyester sheet, and as a result, excellent initial adhesive strength can be expressed. it can. Therefore, conventionally, when a polyester sheet and a solar cell encapsulant (EVA) are adhered, peeling often occurs between the polyester sheet and the adhesive layer when a peel test is performed. For example, since the adhesive strength between the polyester sheet and the adhesive layer is dramatically increased, so-called cohesive failure in which peeling occurs inside the adhesive layer, or peeling occurs at the interface between the adhesive layer and the solar cell sealant (EVA). It becomes.

  Here, the polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure is, specifically, a polyol component (II-1), a dicarboxylic acid component (II-2), and, if necessary, mono Examples thereof include those obtained by reacting the carboxylic acid component (II-3) to produce an intermediate polyester polyol (ii) and then reacting it with an isocyanate group-containing carbodiimide compound (II-4). Under the present circumstances, by using what contains an unsaturated double bond in any of a polyol component (II-1), a dicarboxylic acid component (II-2), and a monocarboxylic acid component (II-3), the said polyester polyol Unsaturated double bonds can be introduced into the resin structure (II). Moreover, a carbodiimide group can be introduce | transduced in the resin structure of the said polyester polyol (II) by using the said isocyanate group containing carbodiimide compound (II-4) as a raw material.

  The reaction rate of the isocyanate group-containing carbodiimide compound (II-4) is as follows: the polyol component (II-1), the dicarboxylic acid component (II-2), and if necessary, the monocarboxylic acid component (II-3). The ratio of 0.5 to 15 parts by mass with respect to 100 parts by mass of polyester (ii), which is the reaction product, is excellent in adhesion to a base sheet such as a polyester sheet. It is preferable from the point.

  Polyester polyol (ii), which is an intermediate of polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure, has a hydroxyl value in the range of 10 to 500 mgKOH / g. From the point that an adhesive coating agent having excellent initial adhesive performance can be obtained.

If such unsaturated double bond-containing polyester resin (II) is classified from the combination of raw material components, for example,
(II-1-a) a polyhydric aliphatic alcohol having 2 to 9 carbon atoms,
(II-2-a) polyester polyols (ii-a) and (II-) which are reaction products of saturated aliphatic dicarboxylic acids, aromatic dicarboxylic acids, or acid anhydrides thereof, and (II-3) vegetable oil fatty acids. 4) Polyester polyol (A) obtained by reacting with an isocyanate group-containing carbodiimide compound;

(II-1-a) a polyhydric aliphatic alcohol having 2 to 9 carbon atoms, and (II-2-b) an unsaturated dicarboxylic acid or an anhydride thereof,
Polyester polyol (B) obtained by reacting polyester polyol (ii-b) which is a reaction product of (II-4) with an isocyanate group-containing carbodiimide compound;

(II-1-a) a polyhydric aliphatic alcohol having 2 to 9 carbon atoms,
(II-2-b) unsaturated dicarboxylic acid or anhydride thereof, and (II-3) vegetable oil fatty acid,
Polyester polyol (C) obtained by reacting polyester polyol (ii-c) which is a reaction product of (II-4) with an isocyanate group-containing carbodiimide compound;

(II-1-a) a polyhydric aliphatic alcohol having 2 to 9 carbon atoms,
(II-1-b) castor oil, and (II-2-a) polyester polyols (ii-d) and (II) which are reaction products of saturated aliphatic dicarboxylic acids, aromatic dicarboxylic acids, or acid anhydrides thereof. -4) Polyester polyol (D) obtained by reacting an isocyanate group-containing carbodiimide compound
Is mentioned.

  Here, as the polyhydric aliphatic alcohol having 2 to 9 carbon atoms (II-1-a), ethylene glycol, neopentyl glycol, diethylene glycol, tetramethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 2 3,4-trimethyl-1,3-pentanediol, 3-methylpentene-1,5-diol, 1,4-cyclohexanedimethanol and the like. Of these, dipropylene glycol is particularly preferred from the viewpoint that appropriate flexibility can be imparted to the coated film and the adhesive layer after coating.

  Examples of saturated aliphatic dicarboxylic acids, aromatic dicarboxylic acids, or acid anhydrides (II-2-a) thereof include benzoic acid, p-tert-butylbenzoic acid, isophthalic acid, phthalic anhydride, terephthalic acid, and orthophthalic acid. 2,6-naphthalenedicarboxylic acid, azelaic acid, sebacic acid, isosebacic acid, oxalic acid, trimellitic acid, (anhydrous) succinic acid, (anhydrous) maleic acid, fumaric acid, (anhydrous) itaconic acid, tetrahydro (anhydrous) Examples include phthalic acid, hexahydro (anhydride) phthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, glutaric acid, adipic acid, pimelic acid, 1,4-cyclohexanedicarboxylic acid and the like. Among these, phthalic anhydride is particularly preferable from the viewpoint of heat and heat resistance.

  Examples of the unsaturated dicarboxylic acid or anhydride (II-2-b) include fumaric acid, maleic acid, and acid anhydrides thereof.

  Examples of the vegetable oil fatty acid (II-3) include coconut oil fatty acid, sesame oil fatty acid, olive oil fatty acid, rapeseed oil fatty acid, soybean oil fatty acid, cacao oil fatty acid, coconut oil fatty acid and the like.

  Examples of the isocyanate group-containing carbodiimide compound (II-4) include a carbodiimide compound having an isocyanate group at both ends of a molecular chain, obtained by a condensation reaction involving decarbonization of an organic diisocyanate compound.

  Examples of organic diisocyanate compounds that can be used here include aromatic diisocyanates, araliphatic diisocyanates, aliphatic diisocyanates, and mixtures of two or more thereof. Specifically, as the aromatic diisocyanate, 1,5-naphthylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate. Examples of the araliphatic diisocyanate include m-xylylene diisocyanate and 1,3-bis1,3-bis (2-isocyanato-2-propyl) benzene. Examples of the aliphatic diisocyanate include hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, methylcyclohexane diisocyanate, 2,5 (2,6) -bis (isocyanato). Methyl) bicyclo [2.2.1] heptane and the like.

  The condensation reaction accompanied by decarbonation of the organic diisocyanate compound can be performed in the presence of a carbodiimidization catalyst. Examples of such catalysts include 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, and 3-methyl-1- Examples thereof include phospholene oxides such as phenyl-2-phospholene-1-oxide and these 3-phospholene isomers, and the reaction temperature is usually preferably in the range of 80 to 200 ° C.

  Among these, the condensation reaction product of araliphatic diisocyanate is particularly excellent in light resistance, non-coloring property and good reactivity of the polyol composition and the adhesive coating agent using the polyol composition. Of these, m-xylylene diisocyanate and 1,3-bis1,3-bis (2-isocyanato-2-propyl) benzene are particularly preferable.

  The isocyanate group-containing carbodiimide compound (II-4) described in detail above has a carbodiimide structure in an average range of 1 to 10 per molecule and becomes a coating agent having excellent adhesion to a base sheet such as a polyester sheet. It is preferable from the point. Moreover, as a carbodiimide equivalent of isocyanate group containing carbodiimide compound (II-4), it is 150-600 g / eq. In particular, 200 to 300 g / eq. It is preferable from the point which is excellent in the adhesiveness to base material sheets, such as a polyester sheet, similarly. In addition, in this invention, carbodiimide equivalent represents the chemical formula amount per mol of carbodiimide groups.

  Among these, (II-1-a) a polyhydric aliphatic alcohol having 2 to 9 carbon atoms, (II-2-b) an unsaturated dicarboxylic acid or an anhydride thereof, (II-3) vegetable oil fatty acid, ( II-4) Polyester polyol (II) obtained by reacting a carbodiimide compound, which is a condensation reaction product of an araliphatic diisocyanate, is preferable from the viewpoint of better adhesion to a solar cell sealing material.

  The unsaturated double bond-containing polyester resin (II) detailed above has a double bond equivalent of 100 to 1000 g / eq. In the range of 200 to 800 g / eq. Those in the range are preferable from the viewpoint of good adhesion to the sealing material in the adhesive coating agent.

  The polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure has a carbodiimide equivalent of 1,500 to 60,000 g / eq. It is preferable that it is the range of the point from which the adhesive performance with respect to a polyester sheet base material becomes favorable.

  In addition, the polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure has a hydroxyl value in the range of 5 to 350 mgKOH / g. Is preferable from the point that becomes even better. Further, the weight average molecular weight (Mw) is preferably in the range of 1,000 to 20,000 from the viewpoint of adhesive strength and wet heat resistance.

  Here, the number average molecular weight (Mn) of the hydroxyl group-containing acrylic resin (I) in the present invention and the weight average molecular weight (Mw) of the polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure. ) Is a value measured by gel permeation chromatography (GPC) under the following conditions.

Measuring device: HLC-8220GPC manufactured by Tosoh
Column: TSK-GUARDCOLUMN SuperHZ-L manufactured by Tosoh Corporation
+ Tosoh Corporation TSK-GEL SuperHZM-M x 4
Detector: RI (differential refractometer)
Data processing: Multi-station GPC-8020 model II manufactured by Tosoh Corporation
Measurement conditions: Column temperature 40 ° C
Solvent tetrahydrofuran
Flow rate: 0.35 ml / min Standard: Monodispersed polystyrene Sample: Filtered 0.2% by mass tetrahydrofuran solution in terms of resin solids with a microfilter (100 μl)

  The blending ratio of the hydroxyl group-containing (meth) acrylic resin (I) detailed above and the polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure is, for example, a mass ratio [(I) / (II)] is in a ratio of 95/5 to 50/50, the adhesion to the sealing material when the adhesive coating agent is used, the strength of the cured coating film, and the heat and humidity resistance are good. To preferred.

  The polyol composition of the present invention comprises a polyfunctional epoxy, in addition to the hydroxyl group-containing (meth) acrylic resin (I) and the polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure. By using Compound (III) together, when the adhesive layer absorbs moisture, the carboxy group generated by hydrolysis of the polyester polyol (A) can be captured by the epoxy group in the polyfunctional epoxy compound (III). It is possible to impart excellent moisture and heat resistance to the adhesive layer.

  Such polyfunctional epoxy compound (III) is preferably a hydroxyl group-containing epoxy compound having a molecular weight in the range of 200 to 1,000. That is, when the molecular weight is 200 or more, in addition to the heat and moisture resistance, the adhesion strength to the substrate is further improved, and when it is 1,000 or less, the compatibility with the polyester polyol (II) is high. It will be good.

  The polyfunctional epoxy compound (III) is, for example, acyclic aliphatic poly (polyethyleneglycol) such as 1,6-hexanediol diglycidyl luter, 1,4-butanediol diglycidyl ether, trimethylolpropane triglycidyl ether, and diethylene glycol diglycidyl ether. Glycidyl ether; cyclohexanedimethanol diglycidyl ether, 3 ′, 4′-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, ε-caprolactone modified 3 ′, 4′-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxy Cyclic aliphatic skeleton-containing epoxy compounds such as hydrogenated products of bisphenol A type epoxy resins; bisphenols such as bisphenol A type epoxy resins and bisphenol F type epoxy resins Type epoxy resins; biphenyl type epoxy resins such as tetramethyl biphenyl type epoxy resin; dicyclopentadiene - phenol addition reaction type epoxy resins. These may be used alone or in combination of two or more. Among these, trimethylolpropane triglycidyl ether and bisphenol type epoxy resin are preferable in that a resin composition excellent in base material adhesion under wet heat conditions and initial adhesive strength can be obtained.

  The polyfunctional epoxy compound (III) includes a hydroxyl group-containing (meth) acrylic resin (I) constituting the polyol composition of the present invention, and a polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure. ) Is preferably blended at a ratio of 4.0 to 30.0 parts by mass from the viewpoint of moisture and heat resistance and blocking resistance.

  In addition, the polyol composition of the present invention includes the hydroxyl group-containing (meth) acrylic resin (I) and the polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure, and further a hydroxyl group content. By using polycarbonate (IV) in combination, the crosslink density of the cured product can be drastically improved, and the adhesive strength and wet heat resistance can be further improved.

  The hydroxyl group-containing polycarbonate (IV) used here has a number average molecular weight (Mn) in the range of 500 to 3,000. The hydroxyl group concentration is moderately high, the crosslinking density during curing is improved, and the heat and moisture resistance is improved. The number average molecular weight (Mn) is more preferably in the range of 800 to 2,000. Here, the method for measuring the number average molecular weight (Mn) is measured under the same conditions as the GPC measurement conditions in the polyester polyol (II) having the unsaturated double bond and the carbodiimide group in the molecular structure. Value.

  The hydroxyl group-containing polycarbonate (IV) has a hydroxyl value in the range of 20 to 300 mgKOH / g, more preferably in the range of 40 to 250 mgKOH / g, from the viewpoint of becoming a resin composition with more excellent curability. . Moreover, it is preferable that it is polycarbonate diol at the point which is excellent in the base-material adhesiveness on wet heat conditions.

  Here, the hydroxyl group-containing polycarbonate (IV) can be produced, for example, by a polycondensation reaction of a polyhydric alcohol and a carbonylating agent.

  Examples of the polyhydric alcohol used in the production of the hydroxyl group-containing polycarbonate (IV) include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, , 8-nonanediol, linear alkanediols such as diethylene glycol; 1,2-propylene glycol, 1,3-butylene glycol, 2-methyl-1,3-propanediol, neopentyl glycol, 3-methyl-1, 5-pentanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2, 4-diethyl-1,5-pentanediol, 1,2-hexane glycol, 1,2-octyl Branched alkanediol call like; 1,4-cyclohexane alicyclic diols dimethanol and the like; trimethylol propane, trifunctional or more branched alkane structure-containing polyfunctional alcohols such as pentaerythritol

  Examples of the carbonylating agent used in the production of the hydroxyl group-containing polycarbonate (IV) include phosgene, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, and diphenyl carbonate. These may be used alone or in combination of two or more.

  Among these, diols selected from 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,4-cyclohexanedimethanol and the carbonylating agent are particularly preferable from the viewpoint of compatibility. What is obtained by reaction with is preferable.

  When the hydroxyl group-containing polycarbonate (IV) is used, the blending ratio thereof includes the hydroxyl group-containing (meth) acrylic resin (I) and unsaturated double bond and carbodiimide group in the molecular structure in the polyol composition of the present invention. Resinous coating agent capable of maintaining high substrate adhesiveness even under wet heat conditions, with respect to a total of 100 parts by mass of polyester polyol (II) being 2.0 to 30.0 parts by mass It is preferable from the point which becomes.

  The polyol composition of the present invention comprises the hydroxyl group-containing (meth) acrylic resin (I), the polyester polyol (II) having the unsaturated double bond and carbodiimide group in the molecular structure, and further the unsaturated double bond and carbodiimide. By using together polyester polyol (V) which does not have a structure, the heat-and-moisture resistance of a contact bonding layer can be improved greatly.

  The polyester polyol (V) that can be used here is preferably a polyester polyol obtained by reacting an aliphatic polyhydric alcohol and a polyvalent carboxylic acid from the viewpoint of adhesive strength. Examples of the aliphatic polyhydric alcohol that can be used here include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 3-methyl-1,5-pentane. Diol, 1,6-hexanediol, neopentyl glycol, methylpentanediol, dimethylbutanediol, butylethylpropanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, etc. Chain aliphatic glycols; Alicyclic glycols such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol; Trifunctionals such as glycerin, trimethylolpropane and pentaerythritol Tetrafunctional aliphatic alcohols; hydrogenated bisphenol A, hydrogenated bisphenol such as hydrogenated bisphenol F.

  On the other hand, examples of the polyvalent carboxylic acid include acyclic aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, and fumaric acid; 1,3-cyclopentanedicarboxylic acid Alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalate Aromatic dicarboxylic acids such as acids, biphenyldicarboxylic acids, 1,2-bis (phenoxy) ethane-p, p'-dicarboxylic acids; anhydrides or ester-forming derivatives of these aliphatic or aromatic dicarboxylic acids; p- Hydroxybenzoic acid, p- (2-hydroxyethoxy) benzoic acid and their dihydroxy Ester-forming derivatives of carboxylic acids include polybasic acids such as dimer acid.

  In the present invention, among these, polyester polyol (V-α), which is a reaction product of aliphatic glycol and aromatic dicarboxylic acid, is particularly preferred from the viewpoint of excellent initial adhesive strength and wet heat resistance. Further, the polyester polyol (V-α) has a molecular weight in the range of 500 to 2000, and a hydroxyl value in the range of 10 to 500 mgKOH / g increases the cross-linking density of the cured product and is moisture resistant. This is preferable from the viewpoint of further improving thermal properties.

  Moreover, the compounding quantity of polyester polyol (V) is the polyester polyol (II) which has the hydroxyl group containing (meth) acrylic resin (I) in the polyol composition of this invention, and an unsaturated double bond and a carbodiimide group in molecular structure. ) Is preferably in a ratio of 2.0 to 30.0 parts by mass with respect to a total of 100 parts by mass from the viewpoint of excellent initial adhesive strength and wet heat resistance.

  The polyol composition of the present invention comprises the polyfunctional epoxy compound (III) together with the hydroxyl group-containing (meth) acrylic resin (I) and the polyester polyol (II) having the unsaturated double bond and carbodiimide group in the molecular structure. ), By adding the hydroxyl group-containing polycarbonate (IV) and the polyester polyol (V), it is possible to adjust the adhesive coating agent to have extremely good adhesive strength in a moist heat environment and excellent in durability. It becomes possible. At this time, the mixing ratio of each component is such that the mixing ratio [(I) / (II) / (III) / (IV) / (V)] based on mass is [(50-80) / (5-25). / (5-15) / (5-15) / (5-15)] It is preferable from the point that the effect of improving the heat and humidity resistance by the combined use of these components becomes remarkable.

  The polyol composition of the present invention may contain other hydroxyl group-containing compounds as necessary in addition to the components (I) to (V) described above. Such hydroxyl group-containing compounds include, for example, polyester polyurethane polyols obtained by reacting polybasic acids, polyhydric alcohols and polyisocyanates, and linear polyester polyurethane polyols obtained by reacting dibasic acids, diols and diisocyanates. , Ether glycols such as polyoxyethylene glycol and polyoxypropylene glycol, bisphenols such as bisphenol A and bisphenol F, and alkylene oxide adducts of bisphenol obtained by adding ethylene oxide, propylene oxide and the like to the bisphenol. . These may be used alone or in combination of two or more.

  The other hydroxyl group-containing compound described above is an effect in the adhesive coating agent of the present invention, the range that does not impair the adhesiveness to the base sheet and wet heat conditions, specifically, in the polyol composition of the present invention, 20 It can be used in the range of not more than mass%.

  The polyol composition described above may further contain various organic solvents. The organic solvent may be contained in such a form that the solvent used in the synthesis of each resin component constituting the polyol composition remains as it is in the polyol composition. Examples of such organic solvents include ketone compounds such as acetone, methyl ethyl ketone (MEK) and methyl isobutyl ketone, cyclic ether compounds such as tetrahydrofuran (THF) and dioxolane, methyl acetate, ethyl acetate, and n-butyl acetate. Examples include ester compounds, aromatic compounds such as toluene and xylene. These may be used alone or in combination of two or more.

  Here, by using the organic solvent, the solid content concentration of the polyol composition and the solid content concentration of the adhesive coating agent can be appropriately adjusted. The amount of the organic solvent is not particularly limited. For example, in the polyol composition which is the main component, the hydroxyl group-containing (meth) acrylic resin (I), the unsaturated double bond and the carbodiimide group have a molecular structure. From the point that the workability of the adjustment of the adhesive coating agent and the subsequent coating is good that the solid content concentration of the polyol component such as polyester polyol (II) in the composition is 40 to 70% by mass preferable.

  The polyol composition of the present invention described in detail above can be used as a polyol component of the adhesive coating agent of the present invention (hereinafter, the polyol composition of the present invention is referred to as “polyol composition (α)”). ). Here, a polyisocyanate compound (β) can be used as a curing agent for the adhesive coating agent.

  Examples of the polyisocyanate compound (β) used here include aliphatic polyisocyanates and aromatic polyisocyanates.

  Examples of the aliphatic polyisocyanate include aliphatic diisocyanates such as 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,8-octamethylene diisocyanate, and L-lysine diisocyanate, or alicyclic systems. A polyisocyanate is mentioned.

  Examples of the alicyclic polyisocyanate include alicyclic diisocyanates such as hydrogenated 4,4'-diphenylmethane diisocyanate (hydrogenated MDI), isophorone diisocyanate, norbornene diisocyanate, and the like.

  Examples of the aromatic polyisocyanate include 4,4′-diphenylmethane diisocyanate (MDI), 4,4′-biphenyl diisocyanate tridenic diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylene diisocyanate, p- Aromatic diisocyanates such as tetramethylxylene diisocyanate, m-tetramethylxylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate Etc.

  In addition, triisocyanate or higher polyisocyanate is also exemplified. Specifically, for example, triphenylmethane triisocyanate, 1,6,11-undecane triisocyanate, 4,4 ′, 4 ″ -triphenylmethane triisocyanate, 2,4,4′-biphenyl triisocyanate, 2,4,4′-diphenylmethane triisocyanate, polymethylene phenyl isocyanate and the like can be mentioned.

  Furthermore, the isocyanurate type polyisocyanate, adduct type polyisocyanate, burette type polyisocyanate, and uretdione type polyisocyanate obtained using the said polyisocyanate compound are mentioned.

  Among these, in particular, non-yellowing polyisocyanates such as aliphatic diisocyanates and alicyclic diisocyanates, and the nurate polyisocyanates, burette polyisocyanates, and uretdione polyisocyanates can provide a coating film with excellent appearance. In view of excellent yellowing resistance, aliphatic diisocyanate nurate type polyisocyanate, aliphatic diisocyanate burette type polyisocyanate, and aliphatic diisocyanate uretdione type polyisocyanate are particularly preferable.

  The blending ratio of the polyol composition (α) and the polyisocyanate compound (β) detailed above is equivalent to the isocyanate group in the polyisocyanate compound (β) with respect to the hydroxyl group in the polyol composition (α). The ratio [NCO / OH] is preferably from 0.25 to 3.00 from the viewpoints of adhesion to the sealing material, strength of the cured coating film, and heat and humidity resistance.

  Here, the hydroxyl group in the polyol composition (α) means the hydroxyl group in the polyester polyol (II) having the hydroxyl group-containing (meth) acrylic resin (I), the unsaturated double bond and the carbodiimide group in the molecular structure. In addition, when the polyfunctional epoxy compound (III) described later has a hydroxyl group, the hydroxyl group, the hydroxyl group in the hydroxyl group-containing polycarbonate (IV), and the other hydroxyl group-containing compound (V) are contained in the compound. It also means a hydroxyl group.

  The adhesive coating agent of the present invention may further contain various organic solvents. Examples of the solvent include ketone compounds such as acetone, methyl ethyl ketone (MEK) and methyl isobutyl ketone, cyclic ether compounds such as tetrahydrofuran (THF) and dioxolane, and esters such as methyl acetate, ethyl acetate and n-butyl acetate. And aromatic compounds such as toluene and xylene. These may be used alone or in combination of two or more.

  In the present invention, after blending the polyol composition (α) as the main agent and the polyisocyanate compound (β) as the curing agent, the fluidity of the adhesive coating agent is appropriately optimized according to the requirements of the coating apparatus. For the purpose of adjusting the level, the organic solvent is preferably blended.

  When the adhesive coating agent of the present invention is used as an adhesive coating agent for solar battery backsheets, various inorganic pigments, organic pigments, or carbon black, fillers, ultraviolet absorbers, antioxidants and / or A light stabilizer or the like can be contained. These various blending materials preferably form a premix previously blended with the polyol composition (α) or the polyisocyanate compound (β), but from the viewpoint of workability, the polyol composition (α). It is preferable to blend in.

  Among the above compounded materials, it is particularly preferable to use titanium dioxide as the inorganic pigment from the viewpoint that the surface of the solar battery cell back sheet is white, and sunlight is reflected to increase the power generation efficiency of the solar battery cell. Further, when emphasizing the design property, it is preferable to blend carbon black.

  For example, titanium dioxide having a mean particle size in the range of 0.1 to 1.5 μm is preferable. Titanium dioxide having an average particle size of 1.5 μm or less is preferable because the surface smoothness of the cured coating film is good.

  Titanium dioxide with an average particle size of 0.1 to 1.5 μm takes into account the toughness of the cured coating film itself and the adhesion that can follow the flexibility of the substrate to be coated, depending on the desired level of weather resistance In addition, it may be added to the main agent and / or the curing agent, but is preferably 25 to 900 parts by weight per 100 parts by weight in total in terms of non-volatile content of all curable components in terms of excellent weather resistance. However, it is more preferable to use 60 to 400 parts by weight in that the whiteness can be as high as when a fluororesin is used.

  Moreover, the said filler can be used as an antiblocking agent, and specifically, a silica with a mean particle diameter of 1-20 micrometers, a resin bead, etc. are mentioned. The amount of the filler used is in the range of 0.1 to 10.0 parts by weight per 100 parts by weight in terms of the nonvolatile content of all curable components, and can impart blocking resistance without deteriorating the adhesive performance. It is preferable from the point.

  As described above, the adhesive coating agent of the present invention is applied to the base material for the back sheet that protects the solar battery cells of the solar battery module, thereby expressing good easy-adhesion performance and excellent adhesive strength. And resistance to moist heat. In addition, the adhesive coating composition of the present invention is applied not only to the back sheet, but also to the base sheet of the sheet when using a transparent resin sheet that replaces the solar cell surface protecting glass plate, It is also possible to develop easy adhesion performance to the solar cell sealing material.

Here, the coating amount of the adhesive coating agent of the present invention on the base sheet is not particularly limited, but is, for example, in the range of 1 to ²⁰ g / m ² , especially 3 to 10 g / m ^2. However, it is preferable at the point which can provide the outstanding weather resistance with a small quantity. 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.

  The adhesive coating agent of the present invention expresses good adhesion performance to the base sheet, but if necessary, for the purpose of imparting further adhesive strength, the base sheet such as a polyester resin sheet is used. Surface treatment may be performed on the surface on which the cured coating film is formed. Examples of the surface treatment include corona treatment, plasma treatment, ozone treatment, flame treatment, and radiation treatment.

The base sheet for the solar battery back sheet used here is a polyester resin sheet such as a polyethylene terephthalate sheet, a polybutylene terephthalate sheet or a polynaphthalene terephthalate; a polyolefin sheet such as a polyethylene sheet, a polypropylene sheet or a polycyclopentadiene sheet; Vinylidene sheet, polyvinylidene fluoride sheet, polytetrafluoroethylene sheet, tetrafluoroethylene-6 fluoropropylene copolymer (FEP) sheet, ethylene-tetrafluoroethylene copolymer (ETFE) sheet ethylene-tetrafluoroethylene Fluorine resin sheets such as copolymer sheets; Acrylic resin sheets such as polyacrylonitrile and polymethyl methacrylate; Polyester resin sheets from the viewpoint of sheet rigidity and cost It is preferably bets, particularly preferably polyethylene terephthalate sheet.

  The thickness of the above-described base sheet for backsheet is not particularly limited, and is preferably in the range of 10 to 400 μm, for example. It is preferable that the thickness is in the range of 80 to 300 μm because it can provide excellent adhesion without giving any influences such as warping and settling on the substrate by drying over time, and can provide excellent weather resistance.

  Such a base sheet for a solar battery back sheet may be composed of only one layer, or may have a multilayer structure of two or more layers. Furthermore, a vapor deposition sheet or the like on which a metal oxide or a nonmetal inorganic oxide is vapor-deposited may be laminated.

  Here, as the metal oxide or non-metal inorganic oxide to be deposited, for example, oxides such as silicon, aluminum, magnesium, calcium, potassium, tin, sodium, boron, titanium, lead, zirconium, yttrium can be used. . Alkali metal and alkaline earth metal fluorides can also be used, and these can be used alone or in combination, such as physical vapor deposition methods such as vacuum vapor deposition and ion plating, and chemical vapor deposition methods such as plasma CVD. The thing vapor-deposited using is mentioned.

  Further, the solar cell backsheet of the present invention may have a barrier property in which a film layer or a coating layer such as a metal foil or a weather resistant resin layer is disposed between a plurality of base material sheets. Good.

  Here, examples of the metal foil include thin films such as aluminum, aluminum oxide, silicon oxide, tin oxide, and magnesium oxide. Among these, aluminum foil is preferable from the viewpoint of corrosion resistance. The thickness is preferably 10 μm to 100 μm, more preferably 20 μm to 50 μm. Various conventionally known adhesive coating agents can be used for laminating the metal foil.

  The weather-resistant resin layer may be a laminate of polyester resin films such as polyvinylidene fluoride film, polyethylene terephthalate, polybutylene terephthalate, polynaphthalene terephthalate, etc., using various known adhesives, or Lumiflon from Asahi Glass Co., Ltd. Examples thereof include a coating layer formed by applying a highly weather-resistant paint such as

  As described above, the base sheet is laminated with a deposited film in which a metal oxide or a non-metallic inorganic oxide is deposited, or a film layer such as a metal foil or a weather-resistant resin layer between a plurality of base sheets. Although the coating layer may be provided, the present invention can exhibit excellent adhesive strength and heat-and-moisture resistance only by applying an adhesive coating agent to the base sheet. It is preferable to use a base sheet composed of only layers. By using such a base sheet composed of only one layer, a sheet can be produced with high productivity while ensuring sufficient performance as a back sheet.

  Next, when the adhesive coating agent of the present invention is applied to the solar cell surface protecting resin sheet, the surface protecting resin sheet that can be used is a polyethylene terephthalate sheet, polybutylene as in the case of the back sheet. Polyester resin sheets such as terephthalate sheet and polynaphthalene terephthalate; polyolefin sheets such as polyethylene sheet, polypropylene sheet and polycyclopentadiene sheet, polyvinyl fluoride sheet, polyvinylidene fluoride sheet, polytetrafluoroethylene sheet, tetrafluoroethylene-6 Fluorine resin sheets such as fluorinated propylene copolymer (FEP) sheet, ethylene-4 fluorinated ethylene copolymer (ETFE) sheet, and ethylene-tetrafluoroethylene copolymer sheet; polyacrylito Le, acrylic resin sheet such as polymethyl methacrylate; and polycarbonate. Among these, a fluororesin sheet, a polyester resin sheet, an acrylic resin sheet, and polycarbonate are preferable from the viewpoint of transparency. Among these, a fluororesin sheet, an acrylic resin sheet, and a polycarbonate are preferable from the viewpoint of weather resistance, and a polyester resin sheet is preferable because it is an inexpensive material and is advantageous in terms of cost.

  The adhesive sheet of the present invention can be obtained by applying the above-described adhesive coating agent of the present invention on the back sheet base sheet or the surface protecting base sheet detailed above and curing it. .

  Here, the curing reaction can be performed, for example, under conditions of 25 ° C. to 60 ° C. for 1 day to 5 days.

  The solar cell module using the adhesive sheet of the present invention described above will be described based on FIG. 1 which is a cross-sectional view of the module. For example, the solar cell (A), the surface protection base material (B), the solar cell The battery cell encapsulant (D) and the back sheet (E) are essential components, and the back sheet (E) is formed on the base sheet (a) and the base sheet (a). The adhesive layer (b), which is a cured product of the adhesive coating agent of the present invention, has an essential layer structure, and the adhesive layer (b) is in contact with the solar cell sealing material (D). Similarly, the one in which the back sheet (E) is disposed can be mentioned. Here, as described above, the surface protective substrate (B) is formed of a resin sheet and a cured layer of the adhesive coating agent of the present invention formed on the resin sheet. The composite sheet arrange | positioned so that a stop material (D) may be sufficient may be sufficient.

  Here, examples of the battery surface protective material (B) include a glass plate, a plastic plate of polycarbonate or polyacrylate, and the like as described above. When polycarbonate or polyacrylate is used, good adhesiveness can be expressed by applying the adhesive coating agent of the present invention to the surface in contact with the sealant, but transparency, weather resistance, toughness, etc. From this point, a glass plate is preferable. Furthermore, white glass with high transparency is preferable among the glass plates.

  Moreover, ethylene vinyl acetate resin (EVA) can be used for the sealing agent (D) used for the solar cell module of this invention. Such a sealing material (D) preferably contains an organic peroxide in the sealing agent (D) because the crosslinking reaction of the adhesive coating agent is promoted.

  Further, as the solar cell (A), for example, a single crystal silicon solar cell element, a polycrystalline silicon solar cell element, a single junction type, an amorphous silicon type solar cell element constituted by a tandem structure type, gallium, etc. III-V compound semiconductor solar cell elements such as arsenic (GaAs) and indium phosphorus (InP), II-VI compound semiconductor solar cell elements such as cadmium tellurium (CdTe), copper / indium / selenium system (CIS system), Copper / indium / gallium / selenium-based (CIGS-based), copper / indium / gallium / selenium / sulfur-based (CIGS-based) I-III-VI group compound semiconductor solar cell elements, dye-sensitized solar cell elements, organic A solar cell element etc. are mentioned.

  The method for producing such a solar cell module is, for example, an ethylene vinyl acetate resin (EVA) sheet serving as a sealing material, a plurality of solar cells (A), an ethylene vinyl acetate resin on the battery surface protective material (B). (EVA) sheet, the back sheet (E) of the present invention is disposed, heated while evacuating, and the two EVA sheets are dissolved to seal the solar cell element. At this time, the plurality of solar cell elements are joined in series by the interconnector (C).

  Hereinafter, the present invention will be described more specifically with reference to examples. Unless otherwise specified, “part” is “part by weight” and “%” is “% by weight”.

  In Examples of the present application, the number average molecular weight (Mn) and the weight average molecular weight (Mw) were measured by gel permeation chromatography (GPC) under the following conditions.

Measuring device: HLC-8220GPC manufactured by Tosoh
Column: TSK-GUARDCOLUMN SuperHZ-L manufactured by Tosoh Corporation
+ Tosoh Corporation TSK-GEL SuperHZM-M x 4
Detector: RI (differential refractometer)
Data processing: Multi-station GPC-8020 model II manufactured by Tosoh Corporation
Measurement conditions: Column temperature 40 ° C
Solvent tetrahydrofuran
Flow rate: 0.35 ml / min Standard: Monodispersed polystyrene Sample: Filtered 0.2% by mass tetrahydrofuran solution in terms of resin solids with a microfilter (100 μl)

Production Example 1 <Synthesis of Acrylic Resin (1)>
Into a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen gas introduction tube, 46 parts by mass of toluene was charged, and stirring was started, and the temperature was raised to 105 ° C. in a nitrogen atmosphere. At the same temperature, 20.0 parts by weight of methyl methacrylate, 5.0 parts by weight of isobutyl acrylate, 69.5 parts by weight of cyclohexyl methacrylate, 5.0 parts by weight of 2-hydroxyethyl methacrylate, 0.5 parts by weight of methacrylic acid And 0.5 parts by mass of perbutyl O (manufactured by NOF Corporation, t-butylperoxy-2-ethylhexanoate) and perbutyl Z (manufactured by NOF Corporation, t-butylperoxybenzoate) What diluted 0.5 mass part in 20 mass parts toluene was dripped simultaneously over 4 hours.
After completion of the dropping, the reaction was continued for 5 hours at the same temperature. Then, toluene and ethyl acetate were added, and it cooled to room temperature, and obtained the organic solvent solution of the acrylic resin (1) of 50% of non volatile matters. Table 1 shows the property values of the resulting acrylic resin (1).

Production Example 2 <Synthesis of Acrylic Resin (2)>
In a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas inlet tube, 18.0 parts by mass of methyl methacrylate, 78.0 parts by mass of n-butyl methacrylate, 2.0 parts by mass of 2-hydroxyethyl methacrylate Then, 2.0 parts by mass of glycidyl methacrylate and 100 parts by mass of toluene were charged, the temperature was raised to 100 ° C. with stirring, 0.15 parts by mass of azobisisobutyronitrile was added, and polymerization was performed for 2 hours. Further, azobisisobutyro 0.07 part by mass of nitrile was added and polymerized for 2 hours, and 0.07 part by mass of azobisisobutyronitrile was further added and reacted for 2 hours.

  Next, 0.03 part by weight of hydroquinone, 0.8 part by weight of dimethylbenzylamine, and 1.0 part by weight of acrylic acid are added and reacted at 100 ° C. for 15 hours to be an organic solvent of acrylic resin (3) having a nonvolatile content of 50%. A solution was obtained. Table 1 shows property values of the obtained acrylic resin (2).

Production Example 4 <Synthesis of Acrylic Resin (3)>
In a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas inlet tube, 18.0 parts by mass of methyl methacrylate, 80.0 parts by mass of n-butyl methacrylate, 2.0 parts by mass of 2-hydroxyethyl methacrylate Then, 100 parts by mass of toluene was charged, the temperature was raised to 100 ° C. while stirring, 0.15 parts by mass of azobisisobutyronitrile was added and polymerization was performed for 2 hours, and 0.07 parts by mass of azobisisobutyronitrile was further added. Polymerization was performed for 2 hours, and 0.07 parts by mass of azobisisobutyronitrile was further added to react for 2 hours. Then, it cooled to room temperature and obtained the organic solvent solution of the acrylic resin (3) of 50 mass% of non volatile matters. Table 1 shows property values of the obtained acrylic resin (3).

Production Example 5 <Synthesis of Polyester Polyol Resin (1)>
In a flask having a stir bar, a temperature sensor, and a rectifying tube, 170 parts by mass of coconut oil fatty acid (“Lunac L-50” manufactured by Kao Corporation), 1100 parts by mass of dipyropyrene glycol, 460 parts by mass of trimethylolpropane, and 540 fumaric acid. Mass parts, 300 parts by mass of phthalic anhydride, and 130 parts by mass of p-tert-butylbenzoic acid were charged, and the esterification reaction was carried out by heating to 180 to 220 ° C. while allowing dry nitrogen to flow into the flask and stirring. When the acid value became 15.0 mgKOH / g or less, the pressure in the flask was reduced to 4000 Pa to promote dehydration condensation, and when the acid value became 10.0 mgKOH / g or less, the reaction was stopped and nonvolatileed with ethyl acetate. A polyester polyol solution (a) having an acid value of 9.8 mgKOH / g and a hydroxyl value of 200 mgKOH / g was obtained by diluting to 80% by mass. Next, 750 parts by mass of the polyester polyol solution (a) (600 parts by mass in terms of non-volatile content), 1,3-bis (2-isocyanato) while allowing dry nitrogen to flow into a flask equipped with a stirring bar, a temperature sensor, and a cooling tube. 2-propyl) benzene condensation reaction product, isocyanate group-containing carbodiimide compound (carbodiimide bond content 4.9 per molecule, carbodiimide equivalent 262 g / eq.) 20 parts by weight, ethyl acetate 115 parts by weight, 70 The urethanization reaction was carried out by heating to ~ 80 ° C. When there is no change in the acid value within 1 hour and the isocyanate content is less than 0.05% by mass, the reaction is terminated. The nonvolatile content is 70% by mass, the acid value is 4.5 mgKOH / g, and the hydroxyl value is 170 mgKOH / g, carbodiimide equivalent 8200 g / eq. A polyester polyol resin (1) was obtained.

Examples 1-9 and Comparative Examples 1-5
The main ingredient component was adjusted according to the formulation shown in Tables 2 to 4 below. Then, the hardening | curing agent was mix | blended with the main ingredient (in Comparative Examples 5-8, a catalyst was further mix | blended), and solid content concentration was adjusted to 30 mass% with ethyl acetate, and the adhesive coating agent was obtained. (The blending amounts in Tables 2 to 4 are solid content conversion values.)

Abbreviations in each table are as follows.
N-3300: Isocyanurate of 1,6-hexamethylene diisocyanate (“Sumidur N-3300” isocyanate group (NCO) content 21.8% by mass, viscosity 2500 mPa · s / 25 ° C., manufactured by Sumika Bayer Urethane Co., Ltd.) )
UM-90: Polycarbonate diol ("Ethanacol" manufactured by Ube Industries, Ltd.), number average molecular weight: about 900, polycarbonate diol obtained by reacting 1,6-hexanediol and carbonate, and 1,4-cyclohexane (Mixture ratio of polycarbonate diol obtained by reacting dimethanol with carbonate ester is 1: 3)
EX-321: a mixture of diglycidyl ether and triglycidyl ether of trimethylolpropane (“Denacol EX-321” epoxy equivalent 140 g / eq. Manufactured by Nagase ChemteX Corporation)
860-80SE: bisphenol A type epoxy resin (DIC Corporation "Epiclon 860-80SE" epoxy equivalent 250 g / eq. Ethyl acetate cut product, solid content 80 mass%)
JER828: bisphenol A type epoxy resin (“JER828” epoxy equivalent 190 g / eq. Manufactured by Mitsubishi Chemical Corporation)
JR-403: Titanium oxide (Taika "JR-403")
M-215: EO-modified diacrylate of isocyanuric acid (“Aronix M-215” manufactured by Toa Gosei Co., Ltd.)
P-1020: Polyester polyol resin obtained from 3-methyl-1,5-pentanediol and terephthalic acid (“Kuraray Polyol P-1020” hydroxyl value 106.0-118.0 mg KOH / g, weight average molecular weight (manufactured by Kuraray) Mw): 1000)
Polyisocyanate compound ^{* 1} : Isocyanurate of hexamethylene diisocyanate blocked with 3,5-dimethylpyrazole (solid content 75% by mass ethyl acetate solution)

Next, the adhesive coating agent obtained in each Example and Comparative Example was applied to a polyethylene terephthalate sheet (“DS-10” manufactured by Toho Sichuan) so that the coating amount after drying was 3 to 4 g / m ^2. After drying at 120 ° C. for 30 seconds to form an easy-adhesion layer, aging was performed at 40 ° C. for 3 days to obtain an adhesive laminate sheet having an easy-adhesion layer.

  The obtained adhesive laminated sheet was cut into a width of 70 mm and a length of 150 mm to obtain an evaluation adhesive laminated sheet.

  Prepare one sheet of EVA sheet cut to a width of 80 mm and a length of 50 mm, a glass sheet (thickness of 2 mm) of 100 mm width and 100 mm length, and in the order of glass sheet, EVA, and adhesive laminated sheet for evaluation Laminate the adhesive layer in contact with the EVA sheet, then evacuate to about 133 Pa at 150 ° C. for 5 minutes using a vacuum laminator, and then press at 150 ° C. for 15 minutes and pressure of 0.1 MPa. Thus, a laminate for evaluation was obtained.

  The adhesive strength and heat-and-moisture resistance were evaluated using a sample obtained by cutting a 10 mm wide cut into the adhesive laminate sheet of the obtained laminate for evaluation. The results are shown in Tables 2-4.

[Adhesion strength evaluation method]
The laminate for evaluation was subjected to a 180 ° peel test at a crosshead speed of 100 mm / min with the unadhered portion sandwiched between upper and lower clips of a tensile tester (manufactured by A & D Co., Ltd.). The obtained measurement values were evaluated as follows.

◎◎◎: 80 N / 10 mm or more ◎◎: 70 N / 10 mm or more to less than 80 N / 10 mm ◎: 60 N / 10 mm or more to less than 70 N / 10 mm ○: 50 N / 10 mm or more to less than 60 N / 10 mm Δ: 30 N / 10 mm or more to 50 N / 10 mm or less X: 10 N / 10 mm or more to less than 30 N / 10 mm XX: less than 10 N / 10 mm [Heat and heat resistance evaluation method]
The laminate for adhesive strength evaluation was subjected to a pressure cooker test (PCT) for 24 to 48 hours (test conditions: 121 ° C. and relative humidity 100%), and the peel strength after the wet heat resistance test was measured under the same conditions as described above. did.

A: Solar cell B: Surface protection base material C: Interconnector D: Sealing material E: Back sheet F: Terminal a: Base material sheet b: Adhesive layer which is a cured product of adhesive coating agent

Claims (18)

  A polyisocyanate-curable adhesive coating agent comprising, as essential components, a hydroxyl group-containing (meth) acrylic resin (I) and a polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure Polyol composition.   The hydroxyl group-containing (meth) acrylic resin (I) is obtained by copolymerizing a hydroxyl group-containing (meth) acrylate (a) and another (meth) acrylic monomer (b) as essential components. The polyol composition for polyisocyanate curable adhesive coating agent according to claim 1.   The hydroxyl group-containing (meth) acrylic resin (I) is a hydroxyl group-containing (meth) acrylate (a), the (meth) acrylate (b-1) esterified with an alkyl group having 1 to 3 carbon atoms, Monomer component constituting hydroxyl group-containing (meth) acrylic resin (I) using (meth) acrylate (b-2) esterified with an alkyl group having 4 to 16 carbon atoms as an essential monomer component Among them, the hydroxyl group-containing (meth) acrylate (a) is 3 to 20% by mass, the (meth) acrylate (b-1) esterified with an alkyl group having 1 to 3 carbon atoms is 15 to 50% by mass, The polyisocyanate curing according to claim 2, wherein the (meth) acrylate (b-2) esterified with an alkyl group having 4 to 16 carbon atoms is copolymerized at a ratio of 30 to 76% by mass. Type contact Sex coating agent for a polyol composition.   The polyol composition for a polyisocyanate-curable adhesive coating agent according to claim 3, wherein the hydroxyl group-containing (meth) acrylic resin (I) is in the range of a hydroxyl value of 1 to 200 mgKOH / g.   The polyester polyol (II) having the unsaturated double bond and carbodiimide group in the molecular structure has a double bond equivalent of 100 to 1,000 g / eq. The polyol composition for a polyisocyanate-curable adhesive coating agent according to claim 1.   The polyester polyol (II) having the unsaturated double bond and carbodiimide group in the molecular structure has a carbodiimide group equivalent of 1500 to 60,000 g / eq. The polyol composition for a polyisocyanate-curable adhesive coating agent according to claim 5, which is in the range of   The polyisocyanate curable adhesive coating agent according to claim 6, wherein the polyester polyol (II) having a unsaturated double bond and a carbodiimide group in the molecular structure is in the range of a hydroxyl value of 10 to 350 mgKOH / g. Polyol composition.   Hydroxyl group-containing (meth) acrylic resin (I), polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure, and a mass ratio [(I) / (II)] of 95/5 to 50 The polyol composition for a polyisocyanate-curable adhesive coating agent according to claim 1, wherein the ratio is / 50. The polyisocyanate according to claim 1, further comprising an epoxy resin (III) in addition to the hydroxyl group-containing (meth) acrylic resin (I) and the polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure. Polyol composition for curable adhesive coating agent.   The compounding ratio of the epoxy resin (III) is a hydroxyl group-containing (meth) acrylic resin (I) which is an essential component of the polyol composition, and a polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure. The polyol composition for a polyisocyanate-curable adhesive coating agent according to claim 9, which is blended at a ratio of 4.0 to 30.0 parts by mass with respect to 100 parts by mass in total.   The polyisocyanate curable type according to claim 1, further comprising a hydroxyl group-containing (meth) acrylic resin (I), a polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure, and further a hydroxyl group-containing polycarbonate (IV). Polyol composition for adhesive coating agent.   The proportion of the hydroxyl group-containing polycarbonate (IV) is a hydroxyl group-containing (meth) acrylic resin (I) which is an essential component of the polyol composition, and a polyester polyol having an unsaturated double bond and a carbodiimide group in the molecular structure ( The polyol composition for polyisocyanate-curable adhesive coating agents according to claim 10, which is blended at a ratio of 2.0 to 30.0 parts by mass with respect to a total of 100 parts by mass of II).   The polyisocyanate according to claim 1, wherein the polyisocyanate further comprises titanium dioxide in addition to the hydroxyl group-containing (meth) acrylic resin (I) and the polyester polyol (II) having an unsaturated double bond and a carbodiimide group in the molecular structure. Polyol composition for curable adhesive coating agent. An adhesive coating agent comprising the polyol composition (α) according to any one of claims 1 to 13 and a polyisocyanate compound (β) as essential components. The blend ratio of the polyol composition (α) and the polyisocyanate compound (β) is equivalent to the equivalent ratio of the isocyanate group in the polyisocyanate compound (β) to the hydroxyl group in the polyol composition (α) [NCO / The adhesive coating agent according to claim 12, wherein OH] is a ratio of 0.25 to 3.00.   A cured product obtained by curing the adhesive coating agent according to claim 14.   The adhesive sheet which apply | coated and hardened the adhesive coating agent of Claim 13 on the polyester base material sheet, and formed the contact bonding layer.   The solar cell (A), the surface protective base material (B), the solar cell sealing material (D), and the back sheet (E) are essential components, and the back sheet (E) is a base sheet. The adhesive layer (b) which is a cured product of the adhesive coating agent according to claim 13 formed on (a) and the substrate sheet (a) has an essential layer structure, and The solar cell module, wherein the back sheet (E) is disposed so that the adhesive layer (b) is in contact with the solar cell sealing material (D).

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