JP2016027153A - Curable adhesive resin composition, and solar cell backside protective sheet prepared therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable adhesive resin composition which can form a cured coating having a low curing strain irrespective of a high crosslinking density.SOLUTION: A curable adhesive resin composition 3 comprises an acrylic copolymer (A) having two or more hydroxy groups in one side chain, and a polyisocyanate compound (B). A ratio between a blocked polyisocyanate compound (b1) and a non-blocked polyisocyanate compound (b2) in the polyisocyanate compound (B) is (b1):(b2)=50 or more to 100:50 or less to 0 (mass ratio).SELECTED DRAWING: Figure 3

Description

The present invention relates to a curable adhesive resin composition capable of forming a cured adhesive layer having excellent long-term durability.
Moreover, this invention relates to the solar cell back surface protection sheet which apply | coated the said curable adhesive resin composition and comprised the curable adhesive resin layer in the outermost surface, and its manufacturing method. Furthermore, this invention distribute | arranges the said curable adhesive resin layer in the said solar cell back surface protection sheet in the position which contact | connects the sealing agent located in the non-light-receiving surface side of a solar cell, The said curable adhesive resin layer is provided. The present invention relates to a cured solar cell module.

In various technical fields such as paints, adhesives, and pressure-sensitive adhesives (pressure-sensitive adhesives), a reaction between an acrylic copolymer that is one of polymers having a hydroxyl group and a polyisocyanate compound that is a crosslinking agent is used. Yes.
For example, in Patent Document 1, the secondary hydroxyl group is bonded to the carbon atom in the alkyl chain at the 8th position or more from the (meth) acryloyloxy group side, and the alkyl chain has 10 to 25 carbon atoms. There is disclosed a coating composition for an automobile body containing an acrylic resin copolymerized with a secondary hydroxyl group-containing (meth) acrylic acid ester having a certain hydroxyalkyl group and a polyisocyanate compound.
Since the secondary hydroxyl group is less reactive than the primary hydroxyl group, the finished appearance and interlayer adhesion of the coating film are improved, but the scratch resistance of the coating film is lowered. In order to make up for such drawbacks, it is disclosed that a decrease in reactivity can be prevented by placing the secondary hydroxyl group of the acrylic resin away from the polymer main chain.
Patent Document 2 also discloses a similar coating composition for automobile bodies.

  Patent Document 3 discloses a water-based floor coating in which two types of acrylic resin and polyisocyanate are dispersed in an aqueous medium, wherein one of the acrylic resins has primary and secondary hydroxyl groups. An aqueous floor coating is disclosed.

  Further, Patent Document 4 discloses a primary hydroxyl group-containing monomer having a primary hydroxyl group in the molecule, a secondary hydroxyl group-containing monomer having a secondary hydroxyl group in the molecule, and / or a tertiary hydroxyl group having a tertiary hydroxyl group. There is disclosed a pressure-sensitive adhesive composition characterized in that it contains a copolymer polymer that is at least copolymerized with a contained monomer and crosslinked with a crosslinking agent.

  Patent Document 5 discloses an example of a back sheet for a solar cell module. A back sheet for a solar cell module in which an acrylic adhesive layer is formed by crosslinking an acrylic polymer obtained by polymerizing a (meth) acryloyl monomer having a specific structure with a curing agent such as a (blocked) polyisocyanate compound. However, as the crosslinkable functional group of the acrylic polymer, a (meth) acryloyl monomer containing one hydroxyl group in one molecule is used.

JP 2009-155371 A JP 2009-144111 A JP 2008-63373 A JP 2009-29948 A JP 2010-263193 A

  The inventions disclosed in Patent Documents 1 to 4 pay attention to the difference in reactivity due to the difference in the type of hydroxyl group (primary, secondary, tertiary) in the acrylic copolymer, and various coating film performances. It is recognized that he was trying to balance. Patent Document 5 describes that by using a (meth) acryloyl monomer having a specific structure, performance can be maintained even in a high-temperature and high-humidity atmosphere when used in a solar cell module.

By the way, generally as shown in FIG. 1, a solar cell module is (I): Surface protection member (II): Light-receiving surface side sealing agent (III): Solar cell (IV): Non-light-receiving surface side sealing agent, And (V): A back surface protective member is provided.
The surface protection member (I) is located on the outermost surface (light receiving surface side) of the solar cell module. In many cases, glass is used.
The sealing agent layers (II) and (IV) are also called filler layers, and are for embedding solar cells. Generally, ethylene-vinyl acetate copolymer resin (EVA) is used. A plurality of solar cells (III) are arranged between two sheet-like EVAs, and are thermocompression-bonded between the front surface protection member (I) and the back surface protection member (V) to form a solar cell module.

Conventionally, the innermost layer (light-receiving surface side) of a back surface protection member for a solar cell module (hereinafter referred to as a back surface protection sheet) has been bonded with an olefin film such as polyethylene with an adhesive or the like. This olefin-based film was melted by heat with the non-light-receiving surface side sealing agent layer (IV) and was firmly bonded.
In recent years, a method of providing a curable adhesive layer on the innermost surface of the back surface protective sheet has been used in place of the olefin film and the adhesive in order to greatly reduce the cost of the solar cell module. In particular, since long-term moist heat resistance is required, acrylics having excellent moist heat resistance have been used.

  Since solar cell modules are mainly used outdoors, their materials and structures are required to have durability and weather resistance. Since the sealing agent layer (II) (IV) in which the solar battery cell is embedded, which is the most important part of the solar battery module, is relatively weak against moisture and humidity, a back surface protection sheet is used for the purpose of protecting this part. Therefore, strong adhesiveness is required at the joint between the sealant layer (IV) and the back surface protective sheet. Moreover, since a solar cell is used over a long period of about 20 years, it is required that the adhesiveness does not deteriorate even if a long-term wet heat resistance test is performed so that it can withstand long-term use.

  An object of the present invention is to provide a curable adhesive resin composition capable of forming a cured coating film having a small curing strain despite a high crosslinking density. In particular, a cured adhesive layer that joins a solar cell back surface protective sheet and a solar cell sealant layer to protect the solar cell from light, heat, rain, snow, dust, etc. from the outside over a long period of time. It aims at provision of the curable adhesive resin composition used suitably for formation.

Since the linear condensation type polyester resin has hydroxyl groups at both ends, when the molecular weight is small, the distance between the hydroxyl groups is short, but the distance increases as the molecular weight increases. On the other hand, in a chain polymerization type hydroxyl group-containing acrylic resin (hydroxyl group-containing acrylic copolymer), the distance between the hydroxyl group-containing monomer and the hydroxyl group-containing monomer is always constant regardless of the molecular weight. That is, when the molecular weight increases, the acrylic main chain becomes longer, but the distance between the side chain having a hydroxyl group and the side chain having a hydroxyl group is constant.
The distance between the hydroxyl group-containing monomer and the hydroxyl group-containing monomer of the acrylic resin is determined by the ratio of the hydroxyl group-containing monomer in the monomer used for copolymerization. When a monomer having one hydroxyl group in one molecule is used, the number (n) of hydroxyl group-containing monomers and the distance (r) between the hydroxyl monomer and the hydroxyl monomer are
r = L / (n + 1) L: Expressed by the length of one unit of copolymerization monomer.
On the other hand, when a monomer having two hydroxyl groups in one molecule is used, the number (n) of hydroxyl group-containing monomers and the distance (r ′) between the hydroxyl monomers and the hydroxyl monomers are r ′ = L ′. / {(N / 2) +1} L ′: Expressed by the length of one unit of copolymerization monomer.

  That is, in the acrylic copolymer having the same hydroxyl value, the use of a monomer having two or more hydroxyl groups in one molecule is more effective than the case of using a monomer having one hydroxyl group in one molecule. Therefore, the distance between the side chain having a hydroxyl group and the side chain having a hydroxyl group becomes long. Even with an acrylic copolymer having the same hydroxyl value, it is possible to obtain a film with less curing strain while using a monomer having two or more hydroxyl groups in one molecule while having a similar crosslinking density. As a result, the present invention has been completed.

That is, the present invention is a curable adhesive resin composition containing an acrylic copolymer (A) having two or more hydroxyl groups in one side chain and a polyisocyanate compound (B), wherein the polyisocyanate Curability in which the ratio of the blocked polyisocyanate compound (b1) to the unblocked polyisocyanate compound (b2) in the compound (B) is (b1) :( b2) = 50 or more and 100: 50 or less to 0 It is an adhesive resin composition.
The acrylic copolymer (A) is
A copolymer (A1) having a (meth) acryloyl monomer having two or more hydroxyl groups in one molecule as a copolymer unit, or a (meth) acryloyl monomer having an epoxy group in one molecule as a copolymer unit In at least one of the copolymer (A2) obtained by reacting an epoxy group in the copolymer with one functional group capable of reacting with the epoxy group and a hydroxyl group-containing compound or water Preferably there is.

The (meth) acryloyl monomer having two or more hydroxyl groups in one molecule is
A functional group capable of reacting with an epoxy group is added to one epoxy molecule in an epoxy group in glycerol 1- (meth) acrylate, glycerol 2- (meth) acrylate, and a (meth) acryloyl monomer having an epoxy group in one molecule. It is preferably at least one selected from the group consisting of (meth) acryloyl monomers obtained by reacting a compound having water and a hydroxyl group or water,
The functional group capable of reacting with the epoxy group is preferably a carboxyl group or an amino group.

It is preferable that at least 50% of the hydroxyl groups in the acrylic copolymer (A) are secondary hydroxyl groups and tertiary hydroxyl groups.
The acrylic copolymer (A) preferably has a hydroxyl value of 2 to 40 (mgKOH / g) and a weight average molecular weight (Mw) of 40,000 to 600,000.
The glass transition temperature is preferably 20 ° C. or higher.

  Moreover, it is preferable that the curable adhesive resin composition of this invention contains 1-20 mass parts of polyisocyanate compounds (B) with respect to said acrylic copolymer (A): 100 mass parts.

Furthermore, the present invention is a solar cell back surface protective sheet having a curable adhesive resin layer (4 ′) as an outermost surface layer on one side of the plastic film (2),
The said curable adhesive resin layer (4 ') is formed from the said curable adhesive resin composition of this invention, and the insoluble content with respect to methyl ethyl ketone is 0 to 50 weight%, The solar cell back surface protection Regarding the sheet.

In addition, the present invention provides a plastic film (2) on one surface,
The curable adhesive resin composition of the present invention is applied, and the solvent is dried to form a curable adhesive resin layer (4 ′) having an insoluble content in methyl ethyl ketone of 0 to 50% by weight. The present invention relates to a method for producing a solar cell back surface protective sheet.

Furthermore, the present invention provides a solar cell surface protection member (I) located on the light-receiving surface side of the solar cell, a sealant layer (II) located on the light-receiving surface side of the solar cell, solar cells (III), solar The solar comprising the sealing agent layer (IV) located on the non-light-receiving surface side of the battery and the solar cell back surface protective sheet of the present invention in contact with the non-light-receiving surface side sealing agent layer (IV). A battery module,
The solar cell module is characterized in that the cured adhesive layer (4) formed from the curable adhesive resin layer (4 ′) is in contact with the non-light-receiving surface side sealing agent layer (IV).

Although the curable adhesive resin composition of the present invention has a high crosslinking density, it can form a cured coating film having a small curing strain. By curing the curable adhesive resin layer (4 ′) formed by applying and drying the curable adhesive resin composition of the present invention in contact with the non-light-receiving surface side sealing agent layer (IV). Forming a solar cell module;
The cured adhesive layer (4) positioned between the plastic film (2) and the non-light-receiving surface side sealant layer (IV) allows the plastic film and the non-light-receiving surface side sealant layer to pass through a long-term wet heat test. Adhesiveness with (IV) is not impaired.

The typical sectional drawing of the conventional or solar cell module of this invention is represented. The typical sectional view of an example of the solar cell back surface protection sheet of the present invention is expressed. The schematic sectional drawing of the other aspect of the solar cell back surface protection sheet of this invention is represented. The schematic sectional drawing of the other aspect of the solar cell back surface protection sheet of this invention is represented.

<Acrylic copolymer (A) having two or more hydroxyl groups in one side chain>
The acrylic copolymer (A) has two or more hydroxyl groups in one side chain derived from the (meth) acryloyl monomer with respect to the main chain formed by copolymerization of the acrylic monomer.
In general, when the crosslinking density is simply increased, a large curing strain is generated and the adhesion is lowered. The crosslinking point between the hydroxyl group and the isocyanate in the acrylic copolymer also serves as an adhesion point with the substrate. When an acrylic copolymer and a polyisocyanate compound are reacted, the curable adhesive resin layer cures between the base film and the cured adhesive layer, starting from the initial adhesion point as the curing proceeds. The distortion which originates in is produced. When the crosslink density is increased, it is considered that the distance between the adhesion points of the base film and the cured adhesive layer is shortened, so that the curing strain caused by the curing cannot be alleviated and the adhesion is lowered.
In addition, as an accelerated durability test, when exposed to a high-temperature and high-humidity atmosphere at 85 ° C. and a relative humidity of 85% for a long period of time, the base film and the cured adhesive layer differ in elongation and shrinkage due to wet heat. Strain is generated at the interface between the film and the cured adhesive layer, and when this strain increases, the adhesion decreases.

In the present invention, by using an acrylic copolymer (A) having two or more hydroxyl groups in one side chain, while obtaining a high crosslinking density in a crosslinking reaction with a polyisocyanate compound (B) described later, The distance between the cross-linking points can be kept long. By increasing the distance between the cross-linking points, the curing strain can be reduced. In addition, the distance between the cross-linking points is increased and stress is relieved due to the difference in elongation and shrinkage between the cured film and the substrate, or the decrease in adhesion due to the strain generated at the interface between the film and the substrate. Can be prevented.
That is, since the acrylic copolymer (A) has two or more hydroxyl groups in one side chain, the number of hydroxyl side chains necessary for obtaining the same hydroxyl value and the same degree of crosslinking is ½ or less. It becomes. As a result, the distance between the cross-linking points becomes longer, and the increase in strain due to the difference in curing strain and elongation / shrinkage can be alleviated.

In the acrylic copolymer (A), as a method for providing two or more hydroxyl group-containing side chains in one side chain, the following two methods may be mentioned.
1. A method of obtaining a copolymer (A1) having a (meth) acryloyl monomer having two or more hydroxyl groups in one molecule as a copolymer unit;
2. A compound having one functional group capable of reacting with an epoxy group and one hydroxyl group in one molecule and a hydroxyl group on an epoxy group in a copolymer having a (meth) acryloyl monomer having an epoxy group in one molecule as a copolymerization unit or This is a method for obtaining a copolymer (A2) obtained by reacting water.
In this document, the term “(meth) acryloyl monomer” is an abbreviation for acryloyl monomer or methacryloyl monomer.

A method for obtaining the copolymer (A1) will be described in detail.
As a (meth) acryloyl-based monomer having two or more hydroxyl groups in one molecule,
Functional group capable of reacting with epoxy group is added to epoxy group in glycerol 1- (meth) acrylate, glycerol 2- (meth) acrylate, or (meth) acryloyl monomer having epoxy group in one molecule in one molecule. Examples thereof include (meth) acryloyl monomers obtained by reacting one compound with a hydroxyl group or water.
Glycerin 1- (meth) acrylate is also called “(meth) acrylic acid-2,3-dihydroxypropyl” and has one primary hydroxyl group and one secondary hydroxyl group. Glycerin 2- (meth) acrylate is also referred to as “(meth) acrylic acid 2-hydroxy-1-hydroxymethylethyl” and has two primary hydroxyl groups.

Examples of the (meth) acryloyl monomer having an epoxy group in one molecule include glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl acrylate, and 3,4-epoxycyclohexylmethyl methacrylate.
A (meth) acryloyl-based monomer having an epoxy group in one molecule is reacted with a functional group capable of reacting with an epoxy group and a compound having one hydroxyl group in one molecule and water, and then secondary by ring opening of the epoxy group. (Meth) acryloyl monomer having two or more hydroxyl groups in one molecule can be obtained. The hydroxyl group in a compound having one functional group capable of reacting with an epoxy group in one molecule and a hydroxyl group may be any of primary, secondary, and tertiary.
As the functional group capable of reacting with the epoxy group, a carboxyl group or an amino group is preferable, and as the amino group, a primary amino group having —NH ₂ , or a secondary amino group in which one of the H is substituted with a substituent. Can be mentioned.

  When a carboxyl group or water is reacted with an epoxy group in a (meth) acryloyl-based monomer having an epoxy group in one molecule, a predetermined amount of a carboxyl group-containing compound or water is added to the monomer, and a basic catalyst is added. In the presence of, the mixture is heated and stirred at a temperature of about 100 ° C to 150 ° C. When the amino group is reacted, the mixture is heated and stirred at a temperature of about 20 ° C to 150 ° C. The reaction end point is determined by observing the disappearance of the absorption peak of the epoxy group by infrared spectroscopy. In these reactions, a polymerization inhibitor can be added or the oxygen concentration in the reaction system can be kept constant in order not to polymerize the (meth) acryloyl group. Moreover, in the case of these reaction, the said monomer can be melt | dissolved in the organic solvent as needed.

  Examples of the compound having a carboxyl group and a hydroxyl group in one molecule include glycolic acid, lactic acid, malic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid. 2-hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid, 12-hydroxystearic acid, ricinoleic acid, 11-hydroxyhexadecanoic acid, 16-hydroxyhexadecanoic acid, 16-hydroxyhexadecenoic acid, Increase 2-hydroxyoctadecanoic acid, 18-hydroxyoctadecanoic acid, 22-hydroxydocosanoic acid, 2-hydroxytetracosanoic acid, dihydroxymyristic acid, dihydroxypaltimic acid, dihydroxystearic acid, dihydroxyarachidic acid, trihydroxypaltimic acid, etc. It can be.

  Examples of the compound having a primary amino group and a hydroxyl group in one molecule include monoethanolamine, 2-amino-2-methyl-1-propanol, 2-amino-1,3-propanediol, and 2-amino-2-hydroxy. Examples thereof include methyl-1,3-propanediol and 2-amino-2-methyl-1,3-propanediol.

Examples of the compound having a secondary amino group and a hydroxyl group in one molecule include N-methylethanolamine, N-ethylethanolamine, Nn-butylethanolamine, Nt-butylethanolamine, and hydroxyethylpiperazine. I can do it.
The compound illustrated above may be used independently and may be used in mixture of 2 or more types.

  Other monomers used in obtaining the copolymer (A1), that is, monomers other than the (meth) acryloyl monomer having two or more hydroxyl groups in one molecule will be described later.

Next, a method for obtaining the copolymer (A2) will be described in detail.
In the copolymer (A2), a functional group capable of reacting with an epoxy group is added to the epoxy group in the copolymer having a (meth) acryloyl monomer having an epoxy group in one molecule as an essential copolymer unit. A compound having one and a hydroxyl group in the molecule or water is reacted to form a secondary hydroxyl group by ring opening of the epoxy group, and two or more hydroxyl groups are introduced into one side chain. That is, while the copolymer (A1) is obtained by copolymerizing a (meth) acryloyl monomer having two or more hydroxyl groups in one molecule as an essential copolymer unit, The union (A2) is different in that a secondary hydroxyl group is formed by ring opening of an epoxy group after copolymerization. (Meth) acryloyl-based monomer having an epoxy group in one molecule used when obtaining the copolymer (A2), a compound having one functional group capable of reacting with an epoxy group and a hydroxyl group in each molecule, The reaction conditions are the same as in the case of obtaining the copolymer (A1).

  As the “other monomer” used in obtaining the acrylic copolymers (A1) and (A2), a hydroxyl group-containing monomer other than a (meth) acryloyl monomer having two or more hydroxyl groups in one molecule (hereinafter referred to as “monomer”) , "Other monomers having a hydroxyl group") can be used in combination.

  Other monomers having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl ( Examples include alkyl (meth) acrylates such as (meth) acrylate.

When other monomers having a hydroxyl group are used in combination, a monomer in which at least 50% of the hydroxyl groups in the resulting acrylic copolymer (A) become a hydroxyl group other than primary (that is, secondary hydroxyl group and tertiary hydroxyl group). Is preferably selected. By setting the hydroxyl group other than the primary in the acrylic copolymer (A) to 50% or more, the curing strain generated in the cured film can be further suppressed, and the adhesion between the film and the substrate after the wet heat resistance test can be reduced. Can be suppressed / prevented.
In addition, the kind and amount of the hydroxyl group in the acrylic copolymer (A1) are the amount (mol) of the monomer having a hydroxyl group provided for the formation of the acrylic copolymer (A1), and 1 in each monomer. It can be determined from the functional group of each hydroxyl group other than grade 1 and grade 1.
In the case of the acrylic copolymer (A2), a monomer having a hydroxyl group and a monomer having an epoxy group that have been used for forming a copolymer before the ring opening of an epoxy group, The amount of each functional group capable of reacting with an epoxy group and a compound having a hydroxyl group (mol), the number of primary, secondary and tertiary hydroxyl groups in the monomer having a hydroxyl group, and the opening of the epoxy group It can be determined from the number of primary, secondary and tertiary hydroxyl groups in the compound obtained and the number of secondary hydroxyl groups produced by ring opening of the epoxy group.

  The acrylic copolymer (A) of the present invention can copolymerize monomers other than the above-mentioned other monomers having a hydroxyl group. Examples of the other monomer include alkyl (meth) acrylate, a monomer having an alicyclic hydrocarbon group, an acidic group-containing monomer, and the like, but the present invention is not limited to such examples.

   Examples of (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and sec-butyl (meth) acrylate. , Tert-butyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, tert -Alkyl (meth) acrylates such as butylhexyl (meth) acrylate, 2-acetoacetoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate and the like.

  As a monomer having an alicyclic hydrocarbon group, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, Examples thereof include dicyclopentenyl (meth) acrylate and dicyclopentanyl (meth) acrylate.

  Examples of the acidic group-containing monomer include (meth) acrylic acid, maleic anhydride, 2- (meth) acryloyloxyethyl-succinic acid, 2- (meth) acryloyloxyethyl-hexahydrophthalic acid, 2- ( And (meth) acryloyloxyethyl-phthalic acid, 2- (meth) acryloyloxyethyl acid phosphate and the like.

The acrylic copolymer (A) can be easily prepared by copolymerizing the monomers.
Examples of the method for polymerizing the monomer include a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method, but the present invention is not limited to such a polymerization method. Among these polymerization methods, the solution polymerization method is preferable because the obtained reaction mixture can be used as it is.

  Hereinafter, one embodiment in the case of preparing an acrylic copolymer by solution polymerization of monomers will be described, but the present invention is not limited to only that embodiment.

  Examples of the solvent used for solution polymerization of the monomer include aromatic solvents such as toluene and xylene; alcohol solvents such as n-butyl alcohol, propylene glycol monomethyl ether, diacetone alcohol, and ethyl cellosolve; ethyl acetate, Examples thereof include ester solvents such as butyl acetate and cellosolve acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; dimethylformamide and the like, but the present invention is not limited to such examples. The amount of the solvent is preferably appropriately determined according to the concentration of the monomer mixture, the molecular weight of the target acrylic polymer, and the like.

  Examples of the polymerization initiator include 2,2′-azobis- (2-methylbutyronitrile), tert-butylperoxy-2-ethylhexanoate, 2,2′-azobisisobutyronitrile, benzoyl Although a peroxide, di-tert-butyl peroxide, etc. are mentioned, this invention is not limited only to this illustration. The amount of the polymerization initiator is usually preferably 0.01 to 30 parts by mass, more preferably 0.05 to 10 parts by mass per 100 parts by mass of the monomer mixture.

  In the polymerization, a chain transfer agent such as n-dodecyl mercaptan may be used to adjust the molecular weight of the resulting acrylic copolymer.

  The polymerization temperature when the monomer is polymerized is usually preferably 40 to 200 ° C, more preferably 40 to 140 ° C.

  Since the polymerization time of the monomer varies depending on the polymerization temperature, the composition of the monomer mixture, the type and amount of the polymerization initiator, and cannot be determined unconditionally, it is preferably determined appropriately according to them.

The hydroxyl value of the acrylic copolymer (A) used in the present invention is preferably 2 to 40 (mgKOH / g). More preferably, it is 4-30 (mgKOH / g).
By using an acrylic copolymer (A) having a hydroxyl value of 2 to 40 (mgKOH / g), the reaction with the polyisocyanate compound (B) essentially comprising the blocked polyisocyanate compound (b1) is sufficient and appropriate. A cured adhesive layer (4) having a sufficient crosslinking density can be formed, and the plastic film (2) and the non-light-receiving surface side sealing agent layer (IV) can be bonded together with sufficient adhesive strength.

The weight average molecular weight (Mw) of the acrylic copolymer (A) used in the present invention is preferably 40,000 to 600,000. More preferably, it is 50,000 to 400,000.
When the acrylic copolymer (A) in the present invention has a weight average molecular weight of 40,000 or more, a curable adhesive resin layer (4 ′) having high film strength can be obtained. As a result, when the solar cell module is formed, the adhesive force between the cured adhesive layer (4) and the sealant layer (IV) does not become weak, and the power generation of the solar cell during long-term use The output does not decrease.
The weight average molecular weight (Mw) of the acrylic copolymer (A) is preferably 600,000 or less from the viewpoint of preventing the formation and mixing of gel-like materials. If the gel-like material is mixed into the cured adhesive layer (4), it may cause defective products when the solar cell module is formed. Further, when the weight average molecular weight (Mw) of the acrylic copolymer (A) is 600,000 or less, a curable adhesive resin composition having an appropriate viscosity and an appropriate solid content can be obtained. When applying to the plastic film (2), it is difficult for problems to occur.
In addition, said weight average molecular weight is the value of polystyrene conversion by the gel permeation chromatography (GPC) of an acrylic copolymer (A). For example, the temperature of a column (KF-805LKF-803L and KF-802 manufactured by Showa Denko KK) is 40 ° C., THF is used as an eluent, the flow rate is 0.2 ml / min, detection is RI, sample concentration 0.02%, and polystyrene was used as a standard sample. The weight average molecular weight of the present invention describes the value measured by the above method.

The glass transition temperature of the acrylic copolymer (A) in the present invention is preferably 20 ° C. or higher. More preferably, it is 25 degreeC or more, and it is more preferable that it is 70 degreeC or less. When the glass transition temperature is set to 20 ° C. or higher, the surface of the curable adhesive resin layer (4 ′) to be formed does not easily become tacky. It becomes difficult to cause.
By setting the glass transition temperature of the acrylic copolymer (A) to 70 ° C. or lower, it is possible to form a strong cured adhesive layer (4) that does not crack during long-term use.
The glass transition temperature referred to here is a glass transition temperature measured by differential scanning calorimetry (DSC) for a resin obtained by drying a solution of the acrylic copolymer (A) to a solid content of 100%. Indicates. For example, for the glass transition temperature, an aluminum pan containing a sample obtained by weighing about 10 mg of a sample and an aluminum pan containing no sample are set in a DSC apparatus, and this is set to −50 using liquid nitrogen in a nitrogen stream. A rapid cooling treatment is performed until the temperature is increased to 150 ° C. at 10 ° C./min, and a DSC curve is plotted. The slope of the DSC curve on the low temperature side (the DSC curve portion in the temperature region where no transition or reaction occurs in the test piece) is extended to the high temperature side, and the slope of the step change portion of the glass transition is maximized. From the intersection with the tangent drawn at such a point, the extrapolated glass transition start temperature (Tig) can be determined, and this can be determined as the glass transition temperature. The glass transition temperature of this invention has described the value measured by said method.

Next, the polyisocyanate compound (B) will be described.
The polyisocyanate compound (B) contains the blocked polyisocyanate compound (b1) as an essential component. The blocked polyisocyanate compound (b1) and the unblocked polyisocyanate compound ( The ratio with b2) is preferably (b1) :( b2) = 50 or more to 100: 50 or less to 0 (mass ratio).

The curable adhesive resin layer (4 ′) in the solar cell back surface protective sheet obtained by applying the curable adhesive resin composition of the present invention to the plastic film (2) is bonded to the sealant layer (IV). Until the solar cell module is manufactured, it is important that it is uncured or semi-cured. Accordingly, it is important to use a polyisocyanate compound (B) that contains the blocked polyisocyanate compound (b1) as an essential component.
That is, when the blocked polyisocyanate compound (b1) forms a solar cell module by stacking the solar cell back surface protective sheet and the sealant layer (IV), the hydroxyl group in the acrylic copolymer (A) It reacts, crosslinks the copolymers, forms the cured adhesive layer (4), and bears the function of bonding the solar cell back surface protective sheet and the sealant layer (IV) together.
On the other hand, the non-blocked polyisocyanate compound (b2) reacts with a part of the hydroxyl groups in the acrylic copolymer (A) when mainly forming the solar cell back surface protective sheet, to crosslink the copolymers, A curable adhesive resin layer (4 ′) is formed. By using the unblocked polyisocyanate compound (b2), the blocking resistance of the curable adhesive resin layer (4 ′) can be improved.

By setting the polyisocyanate compound (B) to 1 part by mass or more with respect to 100 parts by mass of the acrylic copolymer (A), a strong cured adhesive layer (4) can be formed. That is, the cured adhesive layer (4) is not peeled off from the plastic film (2) or the sealant layer (IV), and the performance deterioration of the solar cell can be prevented during long-term use.
On the other hand, by setting the polyisocyanate compound (B) to 20 parts by mass or less with respect to 100 parts by mass of the acrylic copolymer (A), a cured adhesive layer (4) having an appropriate crosslinking density can be formed. High adhesive strength.

It is important that the polyisocyanate compound (B) of the present invention has two or more isocyanate groups in one molecule, and examples thereof include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates. .
One type of polyisocyanate compound (B) may be used, or two or more types of compounds may be used in combination.

  Aromatic polyisocyanates include 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-triisocyanate. Range isocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 ', 4 " -A triphenylmethane triisocyanate etc. can be mentioned.

  Aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate. 2,4,4-trimethylhexamethylene diisocyanate and the like.

  Examples of alicyclic polyisocyanates include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl- Examples include 2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), 1,4-bis (isocyanatomethyl) cyclohexane and the like.

  In addition to the polyisocyanate, an adduct of the polyisocyanate and a polyol compound such as trimethylolpropane, a burette or isocyanurate of the polyisocyanate, and further, the polyisocyanate and a known polyether polyol or polyester polyol, Examples thereof include adducts with acrylic polyol, polybutadiene polyol, polyisoprene polyol and the like.

  Among these polyisocyanate compounds (B), a low-yellowing type aliphatic or alicyclic polyisocyanate is preferable from the viewpoint of design, and an isocyanurate is preferable from the viewpoint of heat-and-moisture resistance. More specifically, an isocyanurate form of hexamethylene diisocyanate (HDI) and an isocyanurate form of 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI) are preferred. Moreover, these mixtures are also used suitably.

  The blocked polyisocyanate compound (b1) can be obtained by reacting almost all of the isocyanate groups of the unblocked polyisocyanate compound (b2) with the blocking agent.

  Examples of the blocking agent include phenols such as phenol, thiophenol, methylthiophenol, xylenol, cresol, resorcinol, nitrophenol, chlorophenol, oximes such as acetone oxime, methyl ethyl ketone oxime, cyclohexanone oxime, methanol, ethanol, n- Alcohols such as propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, t-butyl alcohol, t-pentanol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, benzyl alcohol , Pyrazol such as 3,5-dimethylpyrazole, 1,2-pyrazole, etc. , Triazoles such as 1,2,4-triazole, halogen-substituted alcohols such as ethylene chlorohydrin and 1,3-dichloro-2-propanol, ε-caprolactam, δ-valerolactam, γ-butyrolactam, β- Examples include lactams such as propyl lactam, and active methylene compounds such as methyl acetoacetate, ethyl acetoacetate, acetylacetone, methyl malonate, and ethyl malonate. In addition, amines, imides, mercaptans, imines, ureas, diaryls, and the like are also included. One blocking agent may be used, or two or more blocking agents may be used in combination.

Among these blocking agents, those having a dissociation temperature of 80 to 150 ° C. are preferable. When the dissociation temperature is less than 80 ° C., when the curable adhesive resin composition is applied and the solvent is volatilized, the curing reaction proceeds and the adhesiveness to the sealant layer may be reduced. . When the dissociation temperature exceeds 150 ° C., the curing reaction does not proceed sufficiently in the vacuum laminating step when the solar cell module is constructed, and the adhesiveness with the sealant layer may be lowered.
Examples of the blocking agent having a dissociation temperature of 80 ° C. to 150 ° C. include methyl ethyl ketone oxime (dissociation temperature: 140 ° C., hereinafter the same), 3,5-dimethylpyrazole (120 ° C.), diisopropylamine (120 ° C.) and the like.

Furthermore, the curable adhesive resin composition of the present invention includes a resin for a binder other than the acrylic copolymer (A) and organic or inorganic fine particles within a range that does not impair the object of the present invention. Alternatively, an organic solvent or the like may be included.
Examples of resins other than the acrylic copolymer (A) include polyester resins, urethane resins, epoxy resins, vinyl resins, fluororesins, and silicone resins.

By containing organic or inorganic fine particles in the curable adhesive resin composition of the present invention, the surface of the curable adhesive resin layer (4 ′) is made uneven to give an antiblocking effect, It can be expected to produce an effect of matting due to unevenness, giving the film strength, making it difficult to be damaged, and improving the adhesive strength.
These fine particles are preferably contained in an amount of 0.01 to 30 parts by mass, more preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A). When the content is 0.01 parts by mass or more, the above effect can be expected, and when the content is 30 parts by mass or less, a strong cured adhesive layer (4) having excellent adhesion can be formed.

  Specific examples of the organic fine particles include polymethyl methacrylate resin, polystyrene resin, nylon (registered trademark) resin, melamine resin, guanamine resin, phenol resin, urea resin, silicone resin, methacrylate resin, acrylate resin, or polymer fine particles, or , Cellulose powder, nitrocellulose powder, wood powder, waste paper powder, rice husk powder, starch and the like. One type of organic particles may be used, or two or more types may be used in combination.

  Specific examples of the inorganic fine particles include inorganic oxides such as magnesium, calcium, barium, zinc, zirconium, molybdenum, silicon, antimony, titanium, and other metal oxides, hydroxides, sulfates, carbonates, silicates, and the like. System fine particles are raised. Further specific examples include silica gel, aluminum oxide, calcium hydroxide, calcium carbonate, magnesium oxide, magnesium hydroxide, magnesium carbonate, zinc oxide, lead oxide, diatomaceous earth, zeolite, aluminosilicate, talc, white carbon, mica Glass fiber, glass powder, glass beads, clay, wollastonite, iron oxide, antimony oxide, titanium oxide, lithopone, pumice powder, aluminum sulfate, zirconium silicate, barium carbonate, dolomite, molybdenum disulfide, iron sand, carbon black, etc. Examples thereof include inorganic particles. One kind of inorganic particles may be used, or two or more kinds may be used in combination.

  Moreover, you may add a hardening accelerator to the curable adhesive resin composition of this invention in the range which does not prevent the effect by this invention as needed. The curing accelerator plays a role as a catalyst for promoting the urethane bond reaction between the hydroxyl group of the acrylic copolymer (A) and the polyisocyanate compound (B). Examples of the curing accelerator include tin compounds, metal salts, bases, etc. Specific examples include tin octylate, dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, tin chloride, iron octylate, cobalt octylate, naphthene. Examples include zinc acid, triethylamine, and triethylenediamine. These can be used alone or in combination.

The curable adhesive resin composition of the present invention may contain an organic solvent. Examples of the organic solvent include aromatic solvents such as toluene and xylene; alcohol solvents such as iso-propyl alcohol, n-butyl alcohol and propylene glycol monomethyl ether; ester systems such as ethyl acetate, butyl acetate and cellosolve acetate. Solvent; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone are listed.
It is preferable to use an organic solvent having a boiling point of 50 ° C to 200 ° C. When the boiling point is lower than 50 ° C., the solvent is likely to volatilize when the curable adhesive resin composition is applied to the substrate, and the solid content becomes high, making it difficult to apply with a uniform film thickness. When the boiling point is higher than 200 ° C., it is difficult to dry the solvent. Two or more solvents may be used.

The curable adhesive resin composition of the present invention can be blended with known pigments such as colored pigments and extender pigments as necessary.
Examples of the coloring pigment include titanium oxide, zinc white, carbon black, cadmium red, molybdenum red, chrome yellow, chromium oxide, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline pigment, and selenium pigment. And perelin pigments. Examples of extender pigments include talc, clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, silica, and alumina white.

The curable adhesive resin composition of the present invention is used for forming the outermost layer on the light-receiving surface side of the solar cell back surface protective sheet. And a solar cell back surface protection sheet is provided for formation of a solar cell module. Since the solar cell module is exposed to the external environment for a long period of time, the solar cell module is required to have high moisture and weather resistance.
Since the cured adhesive layer (4) formed from the curable adhesive resin composition of the present invention is also exposed to the external environment for a long period of time, high moisture and heat resistance and weather resistance are required.
For the purpose of imparting weather resistance to the curable adhesive resin composition of the present invention, it may further contain an ultraviolet absorber, an ultraviolet stabilizer and the like.
Examples of UV absorbers include organic UV absorbers such as benzotriazole UV absorbers, benzophenone UV absorbers, triazine UV absorbers, and indole UV absorbers, and inorganic systems such as zinc oxide and titanium oxide. UV absorbers such as UV absorbers are raised.

As the ultraviolet stabilizer, an ultraviolet stabilizer such as a hindered amine compound is preferably used. An ultraviolet absorber or ultraviolet stabilizer may be added to the curable adhesive resin composition as an additive, or an ultraviolet absorber or ultraviolet stabilizer having a functional group is reacted with an acrylic copolymer. It may be used in combination with other resins.
These ultraviolet absorbers and ultraviolet stabilizers are 0.1 to 30 parts by mass, preferably 1 to 20 parts per 100 parts by mass of the solid content of the curable adhesive resin composition excluding the ultraviolet absorbers and ultraviolet stabilizers. It is preferable to use parts by mass.

  In the curable adhesive resin composition in the present invention, if necessary, a filler, a thixotropy imparting agent, an antioxidant, an antioxidant, an antistatic agent, a flame retardant, as long as the effects of the present invention are not hindered. Various additives such as thermal conductivity improvers, plasticizers, anti-sagging agents, antifouling agents, antiseptics, bactericides, antifoaming agents, leveling agents, curing agents, thickeners, pigment dispersants, silane coupling agents An agent may be further added.

Next, the solar cell back surface protection sheet of this invention is demonstrated based on a figure.
The solar cell back surface protection sheet (V) of this invention is located in a non-light-receiving surface in the solar cell module shown in FIG.
In the solar cell back surface protective sheet (V) of the present invention, as shown in FIGS. 2, 3, and 4, the weather resistant protective layer (1) constitutes one surface, and the curable adhesive resin layer (4 ′) is formed. It can be set as the aspect which comprises the other surface.
The curable adhesive resin layer (4 ′) is disposed so as to be in contact with the non-light-receiving surface side sealing agent (IV) shown in FIG. 1 when the solar cell module is formed. Therefore, in the formed solar cell module, the cured adhesive layer (4) is the innermost layer on the non-light-receiving surface side.

Such a solar cell back surface protective sheet can be obtained by the following method.
For example, the composition for forming a weather-resistant protective layer is applied to one surface of the plastic film (2), cured by heating, provided with a weather-resistant protective layer (1), and on the other surface of the plastic film (2), The curable adhesive resin composition of the present invention is applied, and the solvent is volatilized by heating and drying at 50 to 150 ° C. for 30 seconds to 2 minutes, and the solvent insoluble content is 0 to 50% which is uncured or partially cured. The curable adhesive resin layer (4 ') which is can be formed, and the solar cell back surface protection sheet of the aspect of FIG. 2 can be obtained.

  Alternatively, a plurality of plastic films (2) are laminated in advance via an adhesive layer (3), and a weather-resistant protective layer-forming composition is applied to one surface of the laminate, thereby providing a weather-resistant protective layer. (1) is provided, the curable adhesive resin composition of the present invention is applied to the other surface of the laminate, and the solvent is volatilized by heating and drying at 50 to 150 ° C. for 30 seconds to 2 minutes. A curable adhesive resin layer (4 ′) that is cured or partially cured and has a solvent insoluble content of 0 to 50% can be formed, and the solar cell back surface protective sheet of the embodiment of FIG. 2 can be obtained.

Alternatively, an adhesive layer is applied to one surface of the plastic film (2), and the solvent is volatilized by heating and drying at 50 to 150 ° C. for 30 seconds to 2 minutes, thereby uncured adhesive layer (3 ′). Form. After forming the adhesive layer (3 ′), the weather-resistant protective film (1) is stacked, and the adhesive layer is cured by aging.
The aging temperature is preferably 30 to 80 ° C, more preferably 40 to 60 ° C. The aging time is usually 2 to 8 days. If the aging temperature is low, the time until the curing is completed is long, and if the aging temperature is high, the time is short.
A method of accelerating curing by evaporating the solvent and heating it at a temperature of 80 to 150 ° C. for 30 seconds to 10 minutes before aging is also suitable.
Next, the curable adhesive resin composition of the present invention is applied to the other surface of the plastic film (2), and the solvent is volatilized by heating and drying at 50 to 150 ° C. for 30 seconds to 2 minutes. A partially cured curable adhesive resin layer (4 ′) having a solvent insoluble content of 0 to 50% can be formed, and the solar cell back surface protective sheet of the embodiment of FIG. 4 can be obtained.

  Alternatively, the curable adhesive resin composition of the present invention is applied to one surface of the plastic film (2), heat-dried, the solvent is volatilized, and the solvent-insoluble content is 0 to 50%. A resin layer (4 ′) is formed. And the solar cell back surface protection sheet of the aspect of FIG. 4 can be obtained also by laminating | stacking a weather-resistant protective film (1) on the other surface of a plastic film (2) through an adhesive bond layer (3). it can.

Various things can be used as a plastic film (2) which is the object which applies the curable adhesive resin composition of this invention.
For example, polyester, polyethylene, polypropylene, triacetyl cellulose, polystyrene, polycarbonate, polyethersulfone, cellophane, polyamide, polyvinyl alcohol, polyacetal, polyphenylene ether, polyphenylene sulfide, polyimide, polyamideimide, polyetherimide, polyetheretherketone, poly Examples thereof include films made of various resins such as fluorine resins such as tetrafluoroethylene and polyvinylidene fluoride, ABS resins, nonyl resins, acrylic resins, and epoxy resins.
Moreover, the vapor deposition film etc. which vapor-deposited the metal oxide and the nonmetallic inorganic oxide etc. can also be used for these resin films.
Furthermore, what laminated | stacked metal foil, such as copper and aluminum, can also be used for these resin-made films using an adhesive agent.
In addition, it does not ask | require whether the surface which apply | coats the curable adhesive resin composition of this invention is a resin film, a vapor deposition layer, or a metal foil.

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

  A conventionally well-known method can be used as a method of apply | coating the curable adhesive resin composition of this invention to a plastic film (2). Specifically, comma coating, gravure coating, reverse coating, roll coating, lip coating, spray coating, etc. can be raised.

  The thickness of the cured adhesive layer (4) in the solar cell back surface protective sheet (V) of the present invention is preferably 0.1 to 30 μm, and more preferably 1 to 20 μm.

As an adhesive used for forming the solar cell back surface protective sheet (V) of the present invention, various adhesives such as a hot-melt type and a UV-curing property can be used in addition to the thermosetting property.
Examples of the thermosetting adhesive include adhesives formed by blending various polyol components and curing agent components represented by isocyanate components. For example, Toyo Morton Co., Ltd. trade name: Dyna Grand, Shin-Etsu Polymer Co., Ltd. trade name: Polymer Ace. Examples of hot melt adhesives include products manufactured by Toray Dow Corning Co., Ltd.
The adhesive used for the formation of the solar cell back surface protective sheet (V) of the present invention is not limited to such examples.

Next, the solar cell module will be described with reference to FIGS.
The solar cell module is formed by laminating a surface protection member (I) positioned on the light receiving surface side of the solar cell module, a sealant layer (II) positioned on the light receiving surface side, and a solar cell (III). The sealing agent layer (IV) located on the non-light-receiving surface side of the battery module and the solar cell back surface protection sheet (V) are sequentially stacked. The curable adhesive resin layer (4 ′) in the solar cell back surface protective sheet (V) is disposed so as to be in contact with the sealant layer (IV). That is, the solar cell back surface so that the curable adhesive resin layer (4 ′) constituting the solar cell back surface protective sheet (V) shown in FIGS. 2, 3 and 4 is in contact with the sealant layer (IV). Stack the protective sheet (V).
Next, the sealing agent layers (II) and (IV) located on the light receiving surface side and the non-light receiving surface side are melted and softened by thermocompression using a vacuum laminator, and the layers are joined to form a solar cell module.
As shown in FIG. 1, solar cells that are sensitive to water and humidity are sealed in the sealant layers (II) and (IV), and the sealant layers (II) and (IV) are further used as a surface protective material. The solar battery cell is protected from water and humidity by being sandwiched between the back surface protection sheets.

Solar cell modules need to withstand long-term use of 10 or 20 years.
In the solar cell module shown in FIG. 1, when the cured adhesive layer (4) (not shown) deteriorates, the sealing state between the sealant layer (IV) and the solar cell back surface protective sheet (V) is impaired, and water Or water vapor permeates and causes deterioration of solar cells. When the solar cell is deteriorated, the power generation efficiency is lowered or a failure is caused.
Even if the cured adhesive layer (4) itself does not deteriorate, heat and humidity are repeatedly applied when the shrinkage and expansion rates of the plastic film (2) and the cured adhesive layer (4) with respect to heat and humidity are greatly different. If this occurs, distortion may occur at the interface between the plastic film (2) and the cured adhesive layer (4) and at the interface between the cured adhesive layer (4) and the sealant layer (IV), which may eventually peel off. There is.
The curable adhesive resin composition of the present invention can form a cured adhesive layer (4) that does not deteriorate or peel off even under severe conditions over a long period of time.

  The temperature of the vacuum laminator is usually about 130 to 160 ° C, and 150 ° C is common. The above-mentioned module material is placed on a heater in a vacuum laminator in a superposed state, and the inside is vacuumed and laminated for about 10 to 30 minutes. After vacuum laminating for about 15 minutes, it may be further heated for about 15 minutes in an oven at about 130 to 160 ° C. at normal pressure.

As the sealant layer (II) and the sealant layer (IV), an ethylene-vinyl acetate copolymer (EVA) is often used.
When peroxide is added to EVA in advance, sealant layer (II) and sealant layer (IV) are improved in heat resistance by thermally melting and crosslinking EVA by heating during vacuum lamination. Solar cell (III) can be fixed inside.

  Although it does not specifically limit as solar cell surface protection member (I), As a general example, plastic plates, such as a glass plate, a polycarbonate plate, a polyacrylate plate, can be raised. In view of transparency, weather resistance, toughness and the like, a glass plate is preferable. Furthermore, white glass with high transparency is preferable among the glass plates.

  As the solar cell (III), an electrode is provided on a photoelectric conversion layer such as crystalline silicon, amorphous silicon, and a compound semiconductor represented by copper indium selenide, and further, these are laminated on a substrate such as glass. Etc. can be illustrated.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by a following example. In the examples, “parts” represents “parts by mass” and “%” represents “% by mass”.

<Synthesis of (meth) acryloyl monomers having two or more hydroxyl groups in one molecule>
Synthesis Example 1 “Synthesis of a-1”
A four-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen introduction tube is charged with 200 g of toluene, 200 g of glycidyl methacrylate (about 1.4 mol), 0.2 g of triethylamine, and 0.06 g of methylhydroquinone. The temperature was raised to 110 ° C. with stirring in a nitrogen atmosphere. When the temperature in the flask reached 110 ° C., 25.3 g (about 1.4 mol) of ion exchange water was added dropwise over 2 hours. The reaction was further continued for 2 hours after completion of the dropwise addition, and the reaction was terminated after confirming that there was no epoxy group with an infrared spectroscopic analyzer. The solid content, acid value, amine value and hydroxyl value of the obtained monomer (a-1) solution were measured and shown in Table 1.
In addition, the hydroxyl group in the monomer (a-1) was primary hydroxyl group: 50%, non-primary (secondary) hydroxyl group: 50%.

Synthesis Examples 2 to 9 “Synthesis of a-2 to a-9”
By the method similar to the synthesis example 1, it synthesize | combined according to the composition and temperature of Table 1, and the monomer (a-2)-(a-9) solution was obtained. (A-1) The solid content, acid value, amine value, and hydroxyl value were measured in the same manner as the solution, and are shown in Table 1.

<Synthesis of Copolymer A1 having (meth) acryloyl monomer having two or more hydroxyl groups in one molecule as a copolymer unit>
Synthesis Example 101 “Acrylic Copolymer (A1-1)”
A 4-necked flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube was charged with 100 parts of ethyl acetate, and the temperature was raised to 77 ° C. while stirring in a nitrogen atmosphere. When the temperature in the flask reached 77 ° C., 11.0 g of methyl methacrylate, 87.0 g of n-butyl methacrylate, 2.0 g of glycerin 1-methacrylate (about 0.0126 mol), 0.8% of azobisisobutyronitrile. The monomer solution mixed with 25 g was dropped over 2 hours. The reaction was continued by adding 0.02 g of azobisisobutyronitrile every hour from 1 hour after the completion of the monomer dropping, and the reaction was continued until the unreacted monomer in the solution was 1% or less. When the unreacted monomer was 1% or less, the reaction was terminated by cooling to obtain an acrylic copolymer (A1-1) solution having a solid content of about 50%. The solid content, hydroxyl value, weight average molecular weight (Mw), and glass transition temperature of the acrylic copolymer (A1-1) solution were measured and shown in Table 2.
In addition, the hydroxyl group in a copolymer (A1-1) is 50% of primary hydroxyl groups derived from glycerol 1-methacrylate, and 50% of hydroxyl groups other than primary (secondary).

Synthesis Examples 102 to 121 “Acrylic Copolymer (A1-2 to A1-21)”
A copolymer was synthesized according to the composition shown in Table 2 by the same method as in Synthesis Example 101. In addition, the number of parts of the monomers in Synthesis Examples 1 to 9 is the mass of the solid content. The solid content, hydroxyl value, weight average molecular weight (Mw), and glass transition temperature of the obtained copolymer solution were measured and shown in Tables 2 to 4.

Synthesis Example 122 “Acrylic copolymer (A1-22)”
Reaction was performed according to the composition of Table-4, and in the same manner as in Example 1, methyl methacrylate, n-butyl methacrylate, 2-hydroxyethyl methacrylate, and the monomer solution (a-4) obtained in Synthesis Example 4 were used. Copolymerized. Thereafter, 0.06 g of methylhydroquinone was added, and further, 2.39 g of methacrylic acid = 2-isocyanatoethyl was added to react with the hydroxyl group derived from methacrylic acid-2-hydroxyethyl. The reaction was terminated by confirming that the isocyanate group had disappeared with an infrared spectroscopic analyzer, and an acrylic copolymer A1-22 solution into which a methacryloyl group was introduced was obtained.
The solid content, hydroxyl value, weight average molecular weight (Mw), and glass transition temperature of the acrylic copolymer A1-22 solution were measured and shown in Table 4.

Comparative Synthesis Examples 123-127 “Synthesis of Acrylic Copolymers (A1-23 to A1-27)”
A copolymer (A1-23 to A1-27) was synthesized according to the composition shown in Table 4 in the same manner as in Synthesis Example 101. The solid content, hydroxyl value, weight average molecular weight (Mw) and glass transition temperature of the obtained (A1-23 to A1-27) copolymer solution were measured and shown in Table 4.
The solid content, amine value, acid value, hydroxyl value, weight average molecular weight (Mw), and glass transition temperature were measured by the methods described below.

<Copolymer A2 having two or more hydroxyl groups in one side chain formed by ring-opening an epoxy group in a copolymer having a (meth) acryloyl monomer having an epoxy group in one molecule as a copolymer unit Synthesis>

Synthesis Example 201 “Synthesis of acrylic copolymer (A2-1)”
A 4-neck flask equipped with a cooling tube, a stirrer, a thermometer, and a nitrogen inlet tube was charged with 100 g of toluene, and the temperature was raised to 77 ° C. while stirring in a nitrogen atmosphere. When the temperature in the flask reached 77 ° C., 10.0 g of methyl methacrylate, 89.0 g of n-butyl methacrylate, 1.0 g (about 0.007 mol) of glycidyl methacrylate, and 0.25 g of azobisisobutyronitrile were added. The mixed monomer solution was added dropwise over 2 hours. The reaction was continued by adding 0.02 g of azobisisobutyronitrile every hour from 1 hour after the completion of the monomer dropping, and the reaction was continued until the unreacted monomer in the solution was 1% or less. Thereafter, 0.1 g of triethylamine was added and the temperature was raised to 110 ° C.
When the temperature in the flask reaches 110 ° C., 0.13 g (about 0.007 mol) of ion exchange water is added and the reaction is continued for 2 hours. After confirming that there is no epoxy group using an infrared spectrometer, the reaction is performed. Ended. The solid content, hydroxyl value, weight average molecular weight (Mw), and glass transition temperature of the resulting acrylic copolymer (A2-1) solution were measured and shown in Table 4.

The hydroxyl groups in the acrylic copolymer (A2-1) are 50% secondary hydroxyl groups generated by ring opening of epoxy groups derived from glycidyl methacrylate, and 50% primary hydroxyl groups derived from water molecules. .

Synthesis Examples 202 to 209 “Synthesis of acrylic copolymers (A2-2) to (A2-9)”
A copolymer was synthesized according to the composition shown in Table 5 by the same method as in Synthesis Example 201. The solid content, hydroxyl value, weight average molecular weight (Mw), and glass transition temperature of the resulting acrylic copolymers (A2-2) to (A2-9) solutions were measured and shown in Table 5.

<Measurement of solid content>
The weight of an aluminum pan with a lid having a diameter of 55 mm and a depth of 15 mm is measured to 4 digits after the decimal point. About 1.5 g of the resin solution is collected in an aluminum dish, and the lid is immediately covered, and the weight is quickly and accurately measured. With the lid removed, place in an oven at 150 ° C. for 10 minutes to dry. After cooling to room temperature, the weight of the aluminum pan and the lid is measured, and the solid content is calculated by the following formula.
Solid content (%) = (weight after drying−weight of aluminum dish) ÷ (weight before drying−weight of aluminum dish) × 100

<Measurement of acid value (AV)>
About 1 g of the resin solution is accurately weighed in a stoppered Erlenmeyer flask, and dissolved by adding 50 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution. To this is added phenolphthalein reagent as an indicator and held for 30 seconds. Thereafter, the solution is titrated with a 0.1 mol / L alcoholic potassium hydroxide solution until the solution becomes light red.
The acid value was determined by the following formula. The acid value is a numerical value of the dry state of the resin.
Acid value (mgKOH / g) = (a × F × 56.1 × 0.1) / S
S: Amount of sample collected x (solid content of sample / 100) (g)
a: Titration of 0.1 mol / L alcoholic potassium hydroxide solution (ml)
F: Potency of 0.1 mol / L alcoholic potassium hydroxide solution

<Measurement of amine value>
About 1.5 g of the resin solution is accurately weighed into a stoppered Erlenmeyer flask, and 50 ml of methyl ethyl ketone is further added and dissolved. Automatic titration is performed using a potentiometric titrator manufactured by Kyoto Electronics Co., Ltd. using 0.02 mol / L perchloric acid (dioxane solution) as a titration reagent. The maximum inflection point on the titration curve is taken as the equivalent point, and the titration amount of 0.02 mol / L perchloric acid (dioxane solution) at this time is determined.
The amine value is determined by the following formula. The amine value was a numerical value of the dry state of the resin.
Amine value (mgKOH / g) = (a × F × 56.1 × 0.02) / S
S: Amount of sample collected x (solid content of sample / 100) (g)
a: Titration amount (ml) of 0.02 mol / L perchloric acid (dioxane solution)
F: 0.02 mol / L perchloric acid (dioxane solution) titer

<< Measurement of hydroxyl value (OHV) >>
About 1 g of the resin solution is accurately weighed in a stoppered Erlenmeyer flask, and dissolved by adding 50 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution. Further, 5 ml of an acetylating agent (a solution in which 25 g of acetic anhydride is dissolved in pyridine to make a volume of 100 ml) is added accurately, heated to 100 ° C. and stirred for about 1 hour. To this, phenolphthalein reagent is added as an indicator and lasts for 30 seconds. Thereafter, the solution is titrated with a 0.5 mol / L alcoholic potassium hydroxide solution until the solution becomes light red. Separately, as a blank test, a solution obtained by adding an acetylating agent only to a toluene / ethanol mixed solution and heating at 100 ° C. for 1 hour is titrated with a 0.5 mol / L alcoholic potassium hydroxide solution.
The hydroxyl value was determined by the following formula. The hydroxyl value was a numerical value of the dry state of the resin.
Hydroxyl value (mgKOH / g) = {(ba) × F × 56.1 × 0.5} / S + D
S: Amount of sample collected x (solid content of sample / 100) (g)
a: Titration volume of 0.5 mol / L alcoholic potassium hydroxide solution (ml)
b: Titration volume of 0.5 mol / L alcoholic potassium hydroxide solution in the blank experiment (ml)
F: Potency of 0.5 mol / L alcoholic potassium hydroxide solution D: Acid value (mgKOH / g)

<< Weight average molecular weight (Mw) >>
The measurement was performed using a Shodex GPC-104 / 101 system manufactured by Showa Denko.
Column Shodex KF-805L + KF-803L + KF-802
Detector Differential refractometer (RI)
Column temperature 40 ° C
Eluent Tetrahydrofuran (THF)
Flow rate 1.0ml / min
Sample concentration 0.02%
Standard sample for calibration curve TSK standard polystyrene

《Glass transition temperature》
The glass transition temperature here refers to the glass transition temperature measured by differential scanning calorimetry (DSC) for a resin obtained by drying a solution of the acrylic copolymer (A) to a solid content of 100%. . An aluminum pan containing a sample weighed about 10 mg and an aluminum pan without a sample were set in a DSC apparatus, and this was rapidly cooled to −50 ° C. using liquid nitrogen in a nitrogen stream, and then The DSC curve is plotted by raising the temperature to 150 ° C. at 10 ° C./min. The slope of the DSC curve on the low temperature side (the DSC curve portion in the temperature region where no transition or reaction occurs in the test piece) is extended to the high temperature side, and the slope of the step change portion of the glass transition is maximized. From the intersection with the tangent drawn at such a point, the extrapolated glass transition start temperature (Tig) was determined, and this was taken as the glass transition temperature.

<Production of blocked polyisocyanate compound (B)>

“Production of Blocked Polyisocyanate Compound (b1-1)”
The isocyanurate form of hexamethylene diisocyanate (HDI) blocked with 3,5-dimethylpyrazole was diluted with ethyl acetate to obtain a resin solution of a blocked polyisocyanate compound (b1-1) having a solid content of 50%.

"Production of blocked polyisocyanate compound (b1-2)"
A trimethylolpropane (TMP) adduct of isophorone diisocyanate (IPDI) blocked with methylethylketoxime was diluted with ethyl acetate to obtain a resin solution of a blocked polyisocyanate compound (b1-2) having a solid content of 50%.

"Production of blocked polyisocyanate compound (b1-3)"
A mixed isocyanurate of HDI and IPDI blocked with 3,5-dimethylpyrazole (HDI / IPDI = 1/1) was diluted with ethyl acetate to give a blocked polyisocyanate compound (b1-3) having a solid content of 50%. ) Resin solution was obtained.

"Production of unblocked polyisocyanate compound (b2)"
The isocyanurate form of hexamethylene diisocyanate (HDI) was diluted with ethyl acetate to obtain a resin solution of an unblocked polyisocyanate compound (b2) having a solid content of 50%.

"Example 1"
10 parts (solid weight) of the blocked polyisocyanate compound (b1-1) is added to 100 parts (solid weight) of the acrylic copolymer (A1-1) obtained in Synthesis Example 101, and the solid content is 35. % Ethyl acetate was added and stirred to obtain a curable adhesive resin composition.

The obtained curable adhesive resin composition is applied to the base film using a bar coater, dried in an oven at 100 ° C. for 1 minute to volatilize the solvents, and curable on the base film. The laminated body 1 in which the adhesive resin layer was formed was obtained. A polyester film (Tetron S (registered trademark), thickness 188 μm, double-sided corona treatment) manufactured by Teijin DuPont Films was used as the base film. The bar coater was selected so that the film thickness after drying was 5 μm.
The laminate 1 was evaluated for insoluble content (%) with respect to methyl ethyl ketone, initial adhesiveness to EVA, and adhesiveness to EVA wet heat over time.

"Examples 2, 3, 10-15"
In the same manner as in Example 1, a curable adhesive resin composition was obtained according to the composition of Table 6. Using the obtained curable adhesive resin composition, a laminate 1 was obtained in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 6.

"Examples 4 to 9"
In the same manner as in Example 1, a curable adhesive resin composition was obtained according to the composition of Table 6. The obtained curable adhesive resin composition was applied to a base film using a bar coater and dried in an oven at 100 ° C. for 1 minute to volatilize the solvents. Next, the laminate 2 is obtained by allowing it to stand in a thermostatic chamber at 50 ° C. for 4 days to age the reaction between the acrylic copolymer and the polyisocyanate compound to form a curable adhesive resin layer on the base film. It was. Then, it evaluated by the method similar to Example 1, and the result is shown in Table 6.

"Example 16"
To 100 parts (solid weight) of the acrylic copolymer (A1-16) obtained in Synthesis Example 116, 100 parts of a titanium oxide pigment CR-97 manufactured by Ishihara Sangyo Co., Ltd. was added as a white pigment, and the solid content was 45%. Ethyl acetate was added so that. Glass beads were added to the pigment mixture and dispersed with Scandic for 1 hour to obtain a dispersion. 5 parts (solid weight) of the blocked polyisocyanate compound (b1-1) is added to the obtained dispersion, and ethyl acetate is added and stirred so that the solid content is 42%, and a white curable adhesive resin is added. A composition was obtained. Using the obtained white curable adhesive resin composition, a laminate 1 was obtained in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 6.

"Examples 17, 18, and 19"
In the same manner as in Example 16, a white curable adhesive resin composition was obtained according to the composition of Table 6. Using the obtained white curable adhesive resin composition, a laminate 1 was obtained in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 6.

"Examples 20, 21, and 22"
In the same manner as in Example 16, a white curable adhesive resin composition was obtained according to the composition of Table 6. The obtained curable adhesive resin composition was applied to a base film using a bar coater and dried in an oven at 100 ° C. for 1 minute to volatilize the solvents. Next, the laminate 2 is obtained by allowing it to stand in a thermostatic chamber at 50 ° C. for 4 days to age the reaction between the acrylic copolymer and the polyisocyanate compound to form a curable adhesive resin layer on the base film. It was. Then, it evaluated by the method similar to Example 1, and the result is shown in Table 6.

"Example 23"
Using the acrylic copolymer (A1-1) obtained in Synthesis Example 101, pigment dispersion was performed in the same manner as in Example 16 to obtain a white dispersion. 5 parts (solid weight) of blocked polyisocyanate compound (b1-1), 5 parts of non-blocked polyisocyanate compound (b2) and dipentaerythritol hexaacrylate (DPHA) were added to the obtained dispersion, and Ethyl acetate was added and stirred so that the solid content was 42% to obtain a white curable adhesive resin composition. Next, the laminate 2 was obtained in the same manner as in Example 20. Then, it evaluated by the method similar to Example 1, and the result is shown in Table 6.

"Examples 24-32"
In the same manner as in Example 16, a white curable adhesive resin composition was obtained according to the composition of Table 6. The obtained white curable adhesive resin composition was evaluated in the same manner as in Example 16. The results are shown in Table 6.

"Comparative Example 1"
5 parts (solid weight) of the blocked polyisocyanate compound (b1-1) are added to 100 parts (solid weight) of the acrylic copolymer (A1-23) obtained in Synthesis Example 123, and the solid content is 35. % Ethyl acetate was added and stirred to obtain a curable adhesive resin composition. Evaluation was performed in the same manner as in Example 1 using the obtained curable adhesive resin composition. The results are shown in Table 6.

"Comparative Example 2"
To 100 parts (solid weight) of the acrylic copolymer (A2-24) obtained in Synthesis Example 124, 10 parts of the blocked polyisocyanate compound (b1-2) was added according to Table 6, and the solid content was 35%. Then, ethyl acetate was added and stirred to obtain a curable adhesive resin composition. A laminate 1 was obtained using the obtained curable adhesive resin composition, and evaluated in the same manner as in Example 1. The results are shown in Table 6.

“Comparative Example 3”
To 100 parts (solid weight) of the acrylic copolymer (A1-25) obtained in Synthesis Example 125, 100 parts of a titanium oxide pigment CR-97 manufactured by Ishihara Sangyo Co., Ltd. was added as a white pigment, and the solid content was 45%. Ethyl acetate was added so that. Glass beads were added to the pigment mixture and dispersed with Scandic for 1 hour to obtain a dispersion.
According to Table 6, 20 parts (solid weight) of the blocked polyisocyanate compound (b1-3) was added to the obtained dispersion, and ethyl acetate was further added and stirred so that the solid content was 42%. An adhesive resin composition was obtained. It evaluated by the method similar to Example 1 using the obtained white curable adhesive resin composition. The results are shown in 6.

“Comparative Example 4”
A white dispersion was obtained in the same manner as in Comparative Example 3 using 100 parts (solid weight) of the acrylic copolymer (A1-26) obtained in Synthesis Example 126. To the obtained dispersion, 10 parts (solid weight) of the blocked polyisocyanate compound (b1-1) and 5 parts (solid weight) of the non-blocked polyisocyanate compound (b2) are added, so that the solid content becomes 42%. Ethyl acetate was added to and stirred to obtain a white curable adhesive resin composition. Next, the laminate 2 was obtained in the same manner as in Example 20. Then, it evaluated by the method similar to Example 1, and the result is shown in Table 6.

"Comparative Example 5"
Using the acrylic copolymer (A1-27) obtained in Synthesis Example 127, according to the composition of Table 6, the laminate 2 was obtained in the same manner as in Example 4, and evaluated in the same manner. The results are shown in Table 6.

“Comparative Example 6”
According to Table 6, ethyl acetate was added to 100 parts (solid weight) of the acrylic copolymer (A1-1) obtained in Synthesis Example 101 so that the solid content would be 35% without adding the polyisocyanate compound. In addition, the mixture was stirred to obtain a curable adhesive resin composition. Evaluation was performed in the same manner as in Example 1 using the obtained curable adhesive resin composition. The results are shown in Table 6.

“Comparative Example 7”
According to Table 6, 10 parts (solid weight) of the unblocked polyisocyanate compound (b2) was added to 100 parts (solid weight) of the acrylic copolymer (A1-1) obtained in Synthesis Example 101. Subsequently, it evaluated by the method similar to the comparative example 5. The results are shown in Table 6.

<Measurement of methyl ethyl ketone insoluble matter (%)>
The base film is cut into a size of 10 cm × 10 cm in advance, and the weight (X) is obtained. Next, the curable adhesive resin composition obtained in each Example and Comparative Example was applied to the film with a bar coater so that the film thickness after drying was 5 μm, and dried at 100 ° C. for 1 minute. Aged in a thermostatic chamber at 50 ° C. for 4 days to prepare a sample. The weight (Y) of the sample is measured. Thereafter, the sample is put in a container containing 500 ml of methyl ethyl ketone and shaken and stirred at 25 ° C. for 1 hour. After 1 hour, remove from the methyl ethyl ketone, wash the surface with fresh methyl ethyl ketone, and then dry the sample at room temperature. The weight (Z) of the sample is measured after drying. The solvent insoluble content (%) is calculated from the following formula.
Methyl ethyl ketone insoluble matter (%) = {(Z) − (X)} ÷ {(Y) − (X)} × 100

<< Preparation of EVA adhesive strength evaluation sample >>
Laminate 1 and laminate 2 obtained in Examples and Comparative Examples on white plate glass, vinyl acetate-ethylene copolymer film (manufactured by Sanvic Co., Ltd., standard cure type, hereinafter referred to as EVA film), polyester film In a state where the curable adhesive resin layers are sequentially stacked so as to be in contact with the EVA film, they are put in a vacuum laminator, evacuated to about 1 torr, heated at a press pressure of 0.1 MPa at 150 ° C. for 30 minutes, and then at normal pressure. Was further heated at 150 ° C. for 30 minutes to prepare a 10 cm × 10 cm square adhesive force evaluation sample.

<< Initial adhesion to EVA >>
From the polyester film side of the sample for adhesive strength evaluation, a 15 mm width was cut with a cutter knife until the surface of the EVA film was reached, and the adhesive strength between the EVA film and the curable adhesive resin layer was measured. For the measurement, a tensile tester was used, and a 180 degree peel test was performed at a pulling speed of 100 mm / min. The obtained measurement values were evaluated as follows.

<< Adhesion to EVA wet heat over time >>
The adhesive strength evaluation sample is held for 2000 hours under environmental conditions of a temperature of 85 ° C. and a relative humidity of 85% RH, and a heat-resistant heat treatment is performed. It was taken out after 2000 hours, and the adhesiveness to EVA was evaluated by the same method as described above.
A: 50 N / 15 mm or more.
A: 30 N / 15 mm or more to less than 50 N / 15 mm.
(Circle) (triangle | delta): 20N / 15mm or more-less than 30N / 15mm.
(Triangle | delta): 10N / 15mm or more-less than 20N / 15mm.
X: Less than 10N / 15mm.
The results are shown in Table 6.

From the result of Table 6, it is a curable adhesive resin composition of the present invention containing an acrylic copolymer (A) having two or more hydroxyl groups in one side chain and a polyisocyanate compound (B). The curable adhesive resin composition of the present invention, in which the polyisocyanate compound (B) is a polyisocyanate compound essentially comprising the blocked polyisocyanate compound (b1), is excellent in EVA adhesiveness.
On the other hand, Comparative Examples 1, 2, and 3 use an acrylic copolymer obtained by copolymerizing a monomer having one hydroxyl group in one molecule. In any case, the adhesiveness to EVA is inferior.
Comparative Example 4 uses an acrylic copolymer that is not copolymerized with a monomer having a hydroxyl group. The initial adhesion to EVA is relatively good, but the wet heat aging adhesion is poor.
Comparative Example 5 uses an acrylic copolymer obtained by copolymerizing a monomer having a primary hydroxyl group and a monomer having a secondary hydroxyl group. The initial adhesion to EVA is relatively good, but the wet heat aging adhesion is poor.
In Comparative Example 6, no polyisocyanate compound is used. Initial adhesion and wet heat aging are poor.
Comparative Example 7 uses only an unblocked polyisocyanate compound. The methyl ethyl ketone insoluble matter is as high as 98%, and the initial adhesiveness and wet heat aging adhesiveness are very poor.

From the above, the curable adhesive resin composition of the present invention uses a specific polyisocyanate compound with respect to a specific acrylic copolymer, thereby making these curable adhesive resin compositions a base film. The cured adhesive layer applied to and dried on the surface exhibits specific solvent solubility,
It has the characteristics that it is excellent in initial adhesiveness to EVA and adhesiveness over time to EVA wet heat.

  A laminate obtained by applying and curing the curable adhesive resin composition of the present invention to a plastic film, a plastic molding, an aluminum foil, an aluminum plate, a copper foil, a tin plate, a galvanized steel plate, a glass plate, a glass bottle, etc. It can be used for solar cell back surface protection sheet, outdoor display, marking film, glass scattering prevention film, antireflection film, heat ray prevention film, etc.

Furthermore, the curable adhesive resin composition of the present invention also has excellent properties such as, for example, excellent adhesiveness with an adhesive such as a silicone-based adhesive, and the adhesiveness hardly decreases even after a wet heat test.
Accordingly, the curable adhesive resin composition of the present invention includes, for example, various recording materials, IC cards, IC tags, etc., packaging materials for chemicals and foods, back surface protection sheets for solar cells, marking films, photosensitive resins, and the like. Architecture such as plates, adhesive sheets, dye-sensitized solar cells, polarizing plate protecting resin films, antireflection resin films, optical diffusion films such as light diffusion films, glass scattering prevention resin films, decorative sheets, window resin films It can be used for resin films for materials, display materials, resin films for indoor and outdoor overlays such as electric signs, and shrink films.

(I): Surface protective member (II): Light-receiving surface side sealing agent (III): Solar cell (IV): Non-light-receiving surface side sealing agent (V): Back surface protection member or solar cell back surface protection sheet ( 1): cured resin layer (2): plastic film (3): adhesive layer (4 ′): curable adhesive resin layer (5): adhesive film

Claims (11)

A curable adhesive resin composition containing an acrylic copolymer (A) having two or more hydroxyl groups in one side chain, and a polyisocyanate compound (B),
The ratio of the blocked polyisocyanate compound (b1) to the non-blocked polyisocyanate compound (b2) in the polyisocyanate compound (B) is (b1) :( b2) = 50 or more to 100: 50 or less to 0 ( A curable adhesive resin composition having a mass ratio). An acrylic copolymer (A) having two or more hydroxyl groups in one side chain,
A copolymer (A1) having a (meth) acryloyl monomer having two or more hydroxyl groups in one molecule as a copolymer unit, or a (meth) acryloyl monomer having an epoxy group in one molecule as a copolymer unit In at least one of the copolymer (A2) obtained by reacting an epoxy group in the copolymer with one functional group capable of reacting with the epoxy group and a hydroxyl group-containing compound or water The curable adhesive resin composition according to claim 1. A (meth) acryloyl monomer having two or more hydroxyl groups in one molecule is
A functional group capable of reacting with an epoxy group is added to one epoxy molecule in an epoxy group in glycerol 1- (meth) acrylate, glycerol 2- (meth) acrylate, and a (meth) acryloyl monomer having an epoxy group in one molecule. The curable adhesive resin composition according to claim 2, which is at least one selected from the group consisting of a (meth) acryloyl monomer obtained by reacting a compound having water and a hydroxyl group or water.   The curable adhesive resin composition according to claim 2 or 3, wherein the functional group capable of reacting with an epoxy group is a carboxyl group or an amino group.   The curable adhesive resin composition according to any one of claims 1 to 4, wherein at least 50% of the hydroxyl groups in the acrylic copolymer (A) are secondary hydroxyl groups and tertiary hydroxyl groups.   The acrylic copolymer (A) has a hydroxyl value of 2 to 40 (mgKOH / g) and a weight average molecular weight (Mw) of 40,000 to 600,000, according to any one of claims 1 to 5. Curable adhesive resin composition.   The curable adhesive resin composition according to any one of claims 1 to 6, wherein the glass transition temperature of the acrylic copolymer (A) is 20 ° C or higher.   Acrylic copolymer (A): The curable adhesive resin composition of any one of Claims 1-7 which contains 1-20 mass of polyisocyanate compounds (B) with respect to 100 mass parts. A solar cell back surface protective sheet having a curable adhesive resin layer (4 ′) as an outermost surface layer on one side of a plastic film (2),
The said curable adhesive resin layer (4 ') is formed from the curable adhesive resin composition of any one of Claims 1-8, and the insoluble content with respect to methyl ethyl ketone is 0-50 weight. %, Solar cell back surface protection sheet. On one side of the plastic film (2)
Applying the curable adhesive resin composition according to any one of claims 1 to 9 to form a curable adhesive resin layer (4 ') having an insoluble content in methyl ethyl ketone of 0 to 50 mass%. The manufacturing method of the solar cell back surface protection sheet characterized by the above-mentioned. Solar cell surface protection member (I) positioned on the light receiving surface side of the solar cell, sealant layer (II) positioned on the light receiving surface side of the solar cell, solar cell (III), on the non-light receiving surface side of the solar cell The solar cell module comprising the solar cell back surface protective sheet according to claim 9, wherein the solar cell module is provided in contact with the positioned sealant layer (IV) and the non-light-receiving surface side sealant layer (IV).
The solar cell module, wherein the cured adhesive layer (4) formed from the curable adhesive resin layer (4 ') is in contact with the non-light-receiving surface side sealing agent layer (IV).

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