WO2014013906A1 - Heat sealing agent, laminate using same, and solar cell module - Google Patents

Abstract

The present invention provides a heat sealing agent characterized by containing: a urethane resin (A); a polyolefin resin (B); a cross-linking agent (C) including at least one type selected from a group comprising a melamine compound, an epoxy compound, an oxazoline compound, a carbodiimide compound, and an isocyanate compound; a compound (D) having a molecular weight of 20-3,000 and having a primary amino group or a hydrazide group; and an aqueous medium (E). This heat sealing agent has excellent adhesiveness to a base material, and can form a heat sealing layer comprising a level of heat and moisture resistance at which a reduction in adhesiveness is not caused by the effects of heat, etc.

Description

HEAT SEALING AGENT, LAMINATE USING SAME, AND SOLAR CELL MODULE

The present invention relates to a heat sealant that can be used for adhesion of various members, in particular, a polar member and a nonpolar member, for example, adhesion of a back sheet layer of a solar cell module.

Materials used for manufacturing automobile parts, home appliances, solar power generation devices, etc., have been made of ethylene-vinyl acetate resin, polyolefin resin, etc., which have been excellent in weather resistance, water resistance, etc., and have excellent moldability and recyclability. Members are widely used.

The ethylene-vinyl acetate resin is generally easily deteriorated by exposure to heat, water (humidity) or the like, and is insufficient in terms of heat and moisture resistance. For this reason, usually, by combining a member made of ethylene-vinyl acetate resin with a glass or polyethylene terephthalate base material to form a composite member, the moisture-heat resistance level at which the deterioration can be suppressed is reduced. In many cases, it is given to the material.

However, since a substrate made of ethylene-vinyl acetate resin or the like is generally a substrate having a low surface polarity, for example, an adhesive may be used to bond the ethylene-vinyl acetate resin substrate or the like to the glass or the like. Even if it can be easily peeled off at the interface between the surface of the ethylene-vinyl acetate resin substrate and the adhesive layer or temporarily bonded, the adhesive layer deteriorates due to the influence of heat, water, etc. May cause peeling.

On the other hand, by adjusting the composition of the adhesive, it is possible to improve the adhesion to nonpolar substrates such as the ethylene-vinyl acetate resin. However, when the base material to be bonded is a polar base material such as the glass or polyethylene terephthalate base material, the adhesion between the polar base material and the adhesive layer is lowered, and also causes peeling over time. was there.

As described above, it has been technically difficult to find an adhesive having excellent adhesion to both the nonpolar substrate and the polar substrate.

As an adhesive having excellent adhesion, for example, an adhesive made of an aqueous dispersion containing an acid-modified polyolefin resin, a polyurethane resin, a fatty acid amide, and a terpene tackifier in a specific ratio in an aqueous medium is known. Such an adhesive is known to be excellent in adhesion to a thermoplastic resin substrate (see, for example, Patent Document 1).

However, since the adhesive does not have excellent adhesion to both the nonpolar base material and the polar base material as described above, it does not deteriorate at the interface between any base material and the adhesive layer. Sometimes peeled off.

Further, since the adhesive is easily deteriorated by exposure to heat, water (humidity), etc., the adhesive layer is deteriorated or peeled over time due to the influence of heat, water, etc. In some cases, the material itself may deteriorate.

By the way, when the substrates are bonded using the adhesive as described above, the adhesive is usually applied to the surface of one of the substrates immediately before the bonding, and then the adhesive layer is completely formed. In many cases, the other base material is laminated on the surface of the adhesive layer having a tackiness before being cured, and then bonded together by curing.

However, this method requires the production of the composite member because it is necessary to perform an operation such as applying an adhesive or removing a solvent contained in the adhesive at a work site where the substrates are bonded together. In some cases, the efficiency was significantly reduced.

JP 2009-235289 A

The problem to be solved by the present invention has, for example, excellent adhesion to both the polar substrate and the nonpolar substrate, and due to the influence of heat, water (humidity), etc. It is to provide a heat sealant capable of forming a heat seal layer having a moisture and heat resistance level that does not cause a decrease in adhesion, a laminate using the heat seal agent, and a solar cell module.

In addition, the problem to be solved by the present invention has, for example, excellent adhesion to both the polar substrate and the nonpolar substrate, and due to the influence of heat, water (humidity), etc. A heat-sealed layer having a heat-and-moisture resistance level that does not cause deterioration or lowering of adhesion can be formed, and heat is crosslinked by applying the heat-sealing agent in advance on one substrate surface and drying it. After forming the seal layer, the other base material is placed on the heat seal layer and heated, whereby the heat seal agent capable of adhering the base material, a laminate using the heat sealant, and a solar cell Is to provide modules.

The inventors of the present invention have found that a heat sealant containing a specific compound having a primary amino group or a hydrazide group can solve the above-mentioned problems while studying to solve the above-mentioned problems.

That is, the present invention provides a crosslinking agent (C) containing at least one selected from the group consisting of urethane resin (A), polyolefin resin (B), melamine compound, epoxy compound, oxazoline compound, carbodiimide compound and isocyanate compound. And a heat sealing agent comprising a compound (D) having a primary amino group or a hydrazide group and a molecular weight of 20 to 3,000, and an aqueous medium (E).

The heat sealant of the present invention has excellent adhesion to not only ethylene-vinyl acetate resin and polyolefin resin widely used in industry but also a substrate made of polyethylene terephthalate, etc. It can be used for bonding nonpolar substrates and polar substrates, and surface coating of these substrates.

Also, the heat sealant of the present invention can remarkably improve the production efficiency of a laminate (composite member) obtained by laminating various substrates, particularly a solar cell module.

The heat sealant of the present invention comprises a urethane resin (A), a polyolefin resin (B), and a crosslinking agent containing at least one selected from the group consisting of melamine compounds, epoxy compounds, oxazoline compounds, carbodiimide compounds and isocyanate compounds ( C), a compound (D) having a primary amino group or hydrazide group and a molecular weight of 20 to 3,000, and an aqueous medium (E).

The urethane resin (A) and the polyolefin resin (B) are preferably dispersed or dissolved independently in the aqueous medium (E), but a part of them binds to form resin particles. Alternatively, so-called core-shell type composite resin particles may be formed.

Especially, it is preferable that the said urethane resin (A) and the said polyolefin resin (B) form a resin particle each independently, and can disperse | distribute it in the said aqueous medium (E).

The resin particles preferably have an average particle diameter in the range of about 10 nm to 500 nm in order to improve the smoothness of the coat film that can be formed. The average particle diameter here refers to the average particle diameter on a volume basis measured by a dynamic light scattering method.

The mass ratio of the urethane resin (A) and the polyolefin resin (B) [urethane resin (A) / polyolefin resin (B)] is preferably in the range of 9/1 to 2/8, and 8/2 Is more preferably in the range of ˜3 / 7, and more preferably in the range of 8/2 to 5/5 in order to achieve both more excellent heat and moisture resistance and excellent adhesion to various substrates. .

In addition, the urethane resin (A) and the polyolefin resin (B) may be contained in a range of 5% by mass to 70% by mass with respect to the total amount of the heat sealant of the present invention. It is preferable for maintaining stability and coating workability, and is more preferably contained in the range of 20% by mass to 70% by mass.

In addition, the urethane resin (A) and the polyolefin resin (B) may have a hydrophilic group from the viewpoint of imparting good dispersion stability in the aqueous medium (E). As the hydrophilic group, for example, an anionic group, a cationic group, and a polyoxyethylene structure as a nonionic group can be used, and it is more preferable to use an anionic group.

As the anionic group, for example, a carboxyl group, a carboxylate group, a sulfonic acid group, a sulfonate group, and the like can be used. Among them, a carboxylate group or a sulfonate partially or completely neutralized with a basic compound. It is preferable to use a group for imparting good water dispersibility to the urethane resin (A) and the polyolefin resin (B).

Further, as the cationic group, for example, a tertiary amino group or a neutralized group thereof using an acid compound or a quaternizing agent can be used.

Examples of the nonionic group include polyoxyalkylene groups such as polyoxyethylene group, polyoxypropylene group, polyoxybutylene group, poly (oxyethylene-oxypropylene) group, and polyoxyethylene-polyoxypropylene group. Can be used.
As said urethane resin (A), from the viewpoint of providing the outstanding adhesiveness and durability with respect to polar base material (I) and nonpolar base material (II), it is over 3,000 and 300,000 or less. It is preferable to use one having a weight average molecular weight.
In addition, as the urethane resin (A), when an epoxy compound is used as a cross-linking agent (C) described later, a functional group that can react with a functional group such as an epoxy group or a hydrolyzable silyl group [X It is preferable to use a material having a high heat and heat resistance and excellent adhesion to various substrates.
Examples of the functional group [X] include a carboxyl group, a hydroxyl group, and an amino group. In addition, in order to make the said urethane resin (A) and the said polyolefin resin (B) exist stably in an aqueous medium (E), the urethane resin and polyolefin resin which have hydrophilic groups, such as an anionic group and a cationic group, Is used, the carboxyl group as the hydrophilic group or the carboxylate group neutralized with a basic compound or the like may be used as the functional group [X] during the crosslinking reaction. It can act and react with a part of the crosslinking agent (C). Therefore, the functional group [X] is neutralized by an anionic group such as a carboxylate group or a sulfonate group neutralized by a basic compound or the like which can function as the hydrophilic group, or by an acid group-containing compound. Cationic groups such as amino groups can also be used. Among the above functional groups [X], a carboxyl group or a carboxylate group is preferable.

In particular, when a carboxyl group is used as the functional group [X], the urethane resin (A) preferably has an acid value of 5 to 70, and has an acid value of 5 to 50. It is preferable to use in order to improve adhesion to various substrates. The polyolefin resin (B) is preferably one having an acid value of 5 to 300, more preferably one having an acid value of 10 to 250.

As the urethane resin (A), a urethane resin (A-1) having a urea bond formed by reacting a urethane resin having an isocyanate group with a compound (a3) having a primary amino group or a hydrazide group. Can be used. Thereby, the adhesiveness with respect to various base materials can be improved further. In particular, it exhibits excellent adhesion at each stage with respect to the surface of a substrate such as a polar substrate (I) subjected to corona treatment. This is presumed to be because a carbonyl group is generated on the surface of the substrate by the corona treatment or the like, and the carbonyl group forms a bond with a nitrogen atom that forms the urea bond.
The urethane resin (A-1) includes a urethane resin having an isocyanate group and a compound (a3) having a primary amino group or a hydrazide group, and the compound (a3) with respect to the isocyanate group of the urethane resin. Equivalent ratio of primary amino group and hydrazide group [total of primary amino group and hydrazide group possessed by compound (a3) / isocyanate group possessed by urethane resin] is reacted in the range of 0.8 to 2. It is preferable to use a material obtained by reacting under the conditions of 1 to 2, particularly excellent for any substrate such as a polar substrate and a nonpolar substrate. More preferable for forming a heat seal layer having adhesiveness, more preferably more than 1 and 2 or less, 1.05 to 1. It is particularly preferred is.

As the urethane resin (A), for example, those obtained by reacting polyol (a1) and polyisocyanate (a2) can be used.

As the polyol (a1), for example, polyester polyol, polycarbonate polyol, polyether polyol, polyolefin polyol and the like can be used alone or in combination of two or more.

Among these, it is preferable to use a polyether polyol because the adhesion to the nonpolar substrate (II) can be further improved.

As the polyether polyol that can be used for the polyol (a1), for example, one obtained by addition polymerization of alkylene oxide using one or more compounds having two or more active hydrogen atoms as an initiator is used. Can do.

Examples of the initiator include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, bisphenol A, glycerin, and triglyceride. Methylolethane, trimethylolpropane and the like can be used.

Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, and tetrahydrofuran.
As the polyether polyol that can be used for the polyol (a1), specifically, polyoxytetramethylene glycol formed by ring opening of tetrahydrofuran is preferably used.
As the polyether polyol, it is preferable to use a polyether polyol having a number average molecular weight of 500 to 3,000 in order to further improve the adhesion to the polar substrate (I) and the nonpolar substrate (II).
The polyether polyol is preferably used in the range of 1,000 to 3,000 with respect to the entire polyol (a1) used in producing the urethane resin (A).

Examples of the polyester polyol that can be used for the polyol (a1) include those obtained by esterifying low molecular weight polyols and polycarboxylic acids, and ring-opening polymerization reactions of cyclic ester compounds such as ε-caprolactone. Polyesters obtained by the above, copolymerized polyesters thereof, and the like can be used.

Examples of the low molecular weight polyol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, and 1,3-butane having a molecular weight of about 50 to 300. Aliphatic polyols such as diols, aliphatic cyclic structure-containing polyols such as cyclohexanedimethanol, bisphenol compounds such as bisphenol A and bisphenol F, and aromatic structure-containing polyols such as alkylene oxide adducts thereof can be used. .

Examples of the polycarboxylic acid that can be used in the production of the polyester polyol include aliphatic polycarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, and naphthalene. Aromatic polycarboxylic acids such as dicarboxylic acids, and anhydrides or ester-forming derivatives thereof can be used.

The polyester polyol preferably has a number average molecular weight in the range of 200 to 5,000.

Moreover, as a polycarbonate polyol which can be used for the said polyol (a1), what is obtained by making carbonate ester and a polyol react, for example, what is obtained by making phosgene, bisphenol A, etc. react can be used. .

As the carbonate ester, methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, diphenyl carbonate, or the like can be used.

Examples of the polyol that can react with the carbonate ester include ethylene glycol, diethylene glycol, 1,2-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, and 3-methyl-1,5. -Pentanediol, 1,4-cyclohexanediol, 1,6-hexanediol, cyclohexanedimethanol and other relatively low molecular weight diols having a molecular weight of 50 to 2,000, polyethylene glycol, polypropylene glycol, and polyhexamethylene Polyester polyols such as adipate can be used.

As the polycarbonate polyol, use of a polyol having a number average molecular weight in the range of 500 to 4,000 allows the nonpolar substrate (eg, ethylene-vinyl acetate resin or polypropylene) to be used without impairing excellent heat and heat resistance. It is preferable for providing adhesion to II).

In addition, as the polyolefin polyol that can be used for the polyol (a1), for example, polyethylene polyol, polypropylene polyol, polyisobutene polyol, hydrogenated (hydrogenated) polybutadiene polyol, and hydrogenated (hydrogenated) polyisoprene polyol are used. Can do.

Further, as the polyol (a1), from the viewpoint of imparting good water dispersion stability to the urethane resin (A), a polyol having a hydrophilic group can be used in combination with the above-described one.

As the polyol having a hydrophilic group, for example, a polyol having an anionic group other than the above-described polyol, a polyol having a cationic group, and a polyol having a nonionic group can be used. Among these, it is preferable to use a polyol having an anionic group or a polyol having a cationic group, and it is more preferable to use a polyol having an anionic group.

As the polyol having an anionic group, for example, a polyol having a carboxyl group or a polyol having a sulfonic acid group can be used.

Examples of the polyol having a carboxyl group include 2,2′-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2′-dimethylolbutyric acid, 2,2′-dimethylolvaleric acid, and the like. Among them, it is preferable to use 2,2′-dimethylolpropionic acid. Moreover, the polyester polyol which has a carboxyl group obtained by making the polyol which has the said carboxyl group react with various polycarboxylic acids can also be used.

Examples of the polyol having a sulfonic acid group include dicarboxylic acids such as 5-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfophthalic acid, and 5 [4-sulfophenoxy] isophthalic acid, and salts thereof, and the aromatic structure. A polyester polyol obtained by reacting with a low molecular weight polyol exemplified as being usable for the production of the polyester polyol (a1-1) having a polyester polyol can be used.

The polyol having a carboxyl group or the polyol having a sulfonic acid group is preferably used in the range where the acid value of the urethane resin (A) is from 10 to 70, more preferably from 10 to 50. preferable. In addition, the acid value said by this invention is the theoretical value computed based on the usage-amount of acid group containing compounds, such as a polyol which has a carboxyl group used for manufacture of the said urethane resin (A).

The anionic group is preferably partially or completely neutralized with a basic compound or the like in order to develop good water dispersibility.

Examples of basic compounds that can be used for neutralizing the anionic group include organic amines having a boiling point of 200 ° C. or higher, such as ammonia, triethylamine, morpholine, monoethanolamine, diethylethanolamine, sodium hydroxide, water, and the like. A metal hydroxide containing potassium oxide, lithium hydroxide or the like can be used. The basic compound is preferably used in the range of basic compound / anionic group = 0.5 to 3.0 (molar ratio) from the viewpoint of improving the water dispersion stability of the obtained heat sealant. More preferably, it is used in the range of 0.8 to 2.0 (molar ratio).

Further, as the polyol having a cationic group, for example, a polyol having a tertiary amino group can be used. Specifically, N-methyl-diethanolamine, a compound having two epoxies in one molecule, and 2 A polyol obtained by reacting with a secondary amine can be used.

The cationic group is preferably partially or completely neutralized with an acidic compound such as formic acid, acetic acid, propionic acid, succinic acid, glutaric acid, tartaric acid, and adipic acid.

The tertiary amino group as the cationic group is preferably partly or entirely quaternized. As the quaternizing agent, for example, dimethyl sulfate, diethyl sulfate, methyl chloride, ethyl chloride and the like can be used, and dimethyl sulfate is preferably used.

Also, as the polyol having a nonionic group, a polyol having a polyoxyethylene structure or the like can be used.

The polyol having a hydrophilic group is preferably used in the range of 0.3% by mass to 10% by mass with respect to the total amount of the polyol (a1) used in the production of the urethane resin (A).

Moreover, as the polyol (a1), in addition to the above-described polyol, other polyols can be used as necessary.

Examples of the other polyol include ethylene glycol, diethylene glycol, 1,2-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, Polyol having a relatively low molecular weight such as 1,4-cyclohexanediol, 1,6-hexanediol, cyclohexanedimethanol, etc. can be used.
In the present invention, neopentyl glycol or the like is preferably used in order to further improve the adhesion of the heat sealant to various substrates.

Examples of the polyisocyanate (a2) that can react with the polyol (a1) include 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, tolylene diisocyanate, Aromatic polyisocyanates such as naphthalene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, cycloaliphatic diisocyanate, dicyclohexylmethane diisocyanate, and aliphatic cyclic structures such as isophorone diisocyanate. Having polyisocyanate It is possible to use the door.

The urethane resin (A) can be produced, for example, by reacting the polyol (a1) and the polyisocyanate (a2) in the absence of a solvent or in the presence of an organic solvent.
When the urethane resin (A-1) obtained by reacting the isocyanate group of the urethane resin with the compound (a3) having a primary amino group or hydrazide group is used as the urethane resin (A). For example, a urethane resin having an isocyanate group is produced by reacting the polyol (a1) with the polyisocyanate (a2) in the absence of a solvent or in the presence of an organic solvent, and then in the urethane resin. When there is a hydrophilic group, a part of or all of the hydrophilic group is neutralized as necessary, and mixed with the aqueous medium (E) to make it a primary amino group or hydrazide. It can manufacture by mixing with the compound (a3) which has group, and making it react with the isocyanate group which the said urethane resin has.

The reaction between the polyol (a1) and the polyisocyanate (a2) is, for example, such that the equivalent ratio of the isocyanate group of the polyisocyanate (a2) to the hydroxyl group of the polyol (a1) is 1.05 to 2.5. Preferably, it is carried out in the range of 1.1 to 2, more preferably.

Examples of the organic solvent that can be used for producing the urethane resin (A) include ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; acetate esters such as ethyl acetate and butyl acetate; nitriles such as acetonitrile. Amides such as dimethylformamide and N-methylpyrrolidone can be used alone or in combination of two or more.

Examples of the compound (a3) having a primary amino group or hydrazide group that can be used for producing the urethane resin (A-1) among the urethane resin (A) include hydrazine, dicarboxylic acid dihydrazide, Carbohydrazide, 1,3-bis (hydrazinocarbonoethyl) -5-isopropylhydantoin, ethanolamine, etc. can be used, and hydrazine or dicarboxylic acid dihydrazide or carbohydrazide is preferably used, and hydrazine is used. Is more preferable for further improving the heat and moisture resistance.
Examples of the dicarboxylic acid dihydrazide include hydrazine, malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, glutaric acid dihydrazide, sebacic acid dihydrazide, isophthalic acid dihydrazide; β-semicarbazide propionic acid hydrazide and the like. Can be used. Of these, the use of hydrazine is preferable for imparting excellent adhesion.

The aqueous formation of the urethane resin (A) produced by the above method can be performed, for example, by the following method.

[Method 1] After neutralizing or quaternizing some or all of the hydrophilic groups of the urethane resin (A) obtained by reacting the polyol (a1) with the polyisocyanate (a2), water is added. A method in which the urethane resin (A) is dispersed in water by dispersing in water and extending the chain as necessary.

[Method 2] A urethane resin (A) obtained by reacting the polyol (a1) with the polyisocyanate (a2) and, if necessary, the compound (a3) having the primary amino group or hydrazide group, The urethane resin (A) is produced by batch or divided charging into a reaction vessel and chain extension reaction, and then part or all of the hydrophilic groups in the resulting urethane resin (A) are neutralized or quaternary. The method of adding water to disperse the water after conversion.

In the above [Method 1] to [Method 2], an emulsifier may be used as necessary. In addition, when water is dissolved or dispersed, a machine such as a homogenizer may be used as necessary.

Examples of the emulsifier include nonionic emulsifiers such as polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene styryl phenyl ether, polyoxyethylene sorbitol tetraoleate, and polyoxyethylene / polyoxypropylene copolymer. Fatty acid salts such as sodium oleate, alkyl sulfates, alkylbenzene sulfonates, alkyl sulfosuccinates, naphthalene sulfonates, polyoxyethylene alkyl sulfates, alkane sulfonate sodium salts, sodium alkyl diphenyl ether sulfonates, etc. Anionic emulsifiers; cationic amines such as alkylamine salts, alkyltrimethylammonium salts, alkyldimethylbenzylammonium salts It is below. Among these, from the viewpoint of maintaining the excellent storage stability of the coating agent of the present invention, it is basically preferable to use an anionic or nonionic emulsifier.

The urethane resin (A) aqueous dispersion in which the urethane resin (A) obtained by the above method is dispersed in an aqueous medium (E) is obtained by changing the urethane resin (A) to 10 to 10% relative to the total amount of the aqueous dispersion. In addition to improving the ease of production of the heat sealant of the present invention, the heat sealant having both excellent heat and moisture resistance and excellent adhesion to various substrates is included. Is preferable.

The urethane resin (A) aqueous dispersion may be a mixture of two or more urethane resins having different compositions. Specifically, two or more urethane resins having different compositions of the polyol (a1) used for the production of the urethane resin can be used in combination.

Next, the polyolefin resin (B) used for the production of the heat sealant of the present invention will be described.

Examples of the polyolefin resin (B) used in the present invention include homopolymers and copolymers such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene and 1-nonene. Specifically, polyethylene, polypropylene, polybutadiene, ethylene-propylene copolymer, natural rubber, synthetic isopropylene rubber, ethylene-vinyl acetate copolymer, and the like can be used. When the polyolefin resin (B) is a copolymer, it may be a random copolymer or a block copolymer.

The polyolefin resin (B) is preferably one having a functional group capable of reacting with a cross-linking agent (C), which will be described later, if necessary, particularly when an epoxy compound is used as the cross-linking agent (C). It is more preferable to use those having a functional group [X] that can react with a functional group such as an epoxy group or a hydrolyzable silyl group.
As said functional group [X], a carboxyl group etc. are mentioned similarly to the functional group [X] which the said urethane resin (A) has, and it is preferable that it is a carboxyl group especially. The functional group [X] may be the same functional group as the hydrophilic group of the polyolefin resin (B). Specifically, when a carboxyl group or a carboxylate group which is an anionic group is used as the hydrophilic group, the carboxyl group or the like may act as the functional group [X] during the crosslinking reaction.

The polyolefin resin (B) having a carboxyl group as the functional group [X] is obtained by reacting the above-exemplified polyolefin resin with an unsaturated carboxylic acid, or obtained by reacting with a vinyl monomer. It is preferable to use so-called modified polyolefin resins such as those obtained and chlorinated.

For example, a carboxyl group as the functional group [X] can be introduced into the polyolefin resin (B) by reacting the polyolefin resin with an unsaturated dicarboxylic acid such as (anhydrous) maleic acid.

Examples of the unsaturated dicarboxylic acid include maleic acid, fumaric acid, itaconic acid, citraconic acid, and anhydrides thereof, and unsaturated dicarboxylic acid esters (butyl maleate, dibutyl maleate, butyl itaconate, etc.) One or more of these can be used. Of these, maleic anhydride is preferred.

The polyolefin resin (B) modified with the unsaturated carboxylic acid has an acid value in the range of 5 to 250 to prevent deterioration of the cured resin layer due to the influence of heat, water (humidity) or the like. In order to prevent a decrease in adhesion to various substrates, it is preferable.

The modification of the polyolefin resin can be performed, for example, by reacting the polyolefin resin as described above with an unsaturated dicarboxylic acid such as maleic acid or the like.

The polyolefin resin (B) is 20,000 to 500,000 in order to prevent the cured resin layer from being deteriorated by the influence of heat, water (humidity), etc., and to prevent the adhesion to various substrates from being lowered. It is preferable to use those having a weight average molecular weight of In addition, the said weight average molecular weight points out the value measured using gel permeation chromatography (GPC).

Next, the crosslinking agent (C) used in the present invention will be described.
As said crosslinking agent (C), what contains 1 or more types chosen from the group which consists of a melamine compound, an epoxy compound, an oxazoline compound, a carbodiimide compound, and an isocyanate compound can be used.
Especially, it is preferable to use combining 1 or more types chosen from the group which consists of a melamine compound, an epoxy compound, and an isocyanate compound, and it is more preferable to use combining a melamine compound and an epoxy compound.
As the melamine compound, it is particularly preferable to use an alkylated methylol melamine resin (c1).
The alkylated methylol melamine resin (c1) can form a crosslinked structure by a self-crosslinking reaction. Further, when a functional group such as a hydroxyl group is produced when the functional group [X] of the urethane resin (A) and the polyolefin resin (B) reacts with the epoxy compound, The alkylated methylol melamine resin (c1) reacts to form a crosslinked structure.

As the alkylated methylol melamine resin (c1), for example, a product obtained by reacting a methylolated melamine resin with a lower alcohol (an alcohol having 1 to 6 carbon atoms) such as methyl alcohol or butyl alcohol is used. Can do. Specifically, an imino group-containing alkylated methylol melamine resin, an amino group-containing alkylated methylol melamine resin, or the like can be used.

As the methylolated melamine resin, for example, amino group-containing methylol-type melamine resin obtained by condensing melamine and formaldehyde, imino group-containing methylol-type melamine resin, trimethoxymethylol-type melamine resin, hexamethoxymethylol-type melamine resin, etc. are used. It is preferable to use a trimethoxymethylol type melamine resin or a hexamethoxymethylol type melamine resin.

The alkylated methylol melamine resin (c1) is preferably used in the range of 3% by mass to 50% by mass with respect to the total mass of the urethane resin (A) and the polyolefin resin (B). It is more preferable to use in the range of 30% by mass. This makes it possible to achieve both excellent heat and moisture resistance that does not cause deterioration of the heat-seal layer and decrease in adhesive strength regardless of heat, water (humidity), etc., and excellent adhesion to various substrates. Is possible.

Moreover, the epoxy compound which can be used for the said crosslinking agent (C) reacts with the functional group [X] which any one or both of the said urethane resin (A) and the said polyolefin resin (B) form, and forms a crosslinked structure. As a result, it can be used for imparting excellent moisture and heat resistance and excellent adhesion to various substrates.
In the present invention, the combination use of the alkylated methylolmelamine resin (c1) and the epoxy compound as the crosslinking agent (C) achieves both excellent heat and heat resistance and excellent adhesion to various substrates. Is particularly preferable.

Moreover, when using an epoxy compound as said crosslinking agent (C), urethane resin (A) and said polyolefin resin (B) are functional groups, such as an epoxy group and a hydrolyzable silyl group, which said epoxy compound has. Those having a functional group [X] capable of reacting with. The functional group possessed by the epoxy compound is specifically an epoxy group, a hydrolyzable silyl group such as an alkoxysilyl group or a silanol group.

As the epoxy compound, those having 2 to 5 epoxy groups, more preferably 3 to 4 epoxy groups can be used.

Examples of the epoxy compound include bisphenol A epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether. Diglycidyl aniline, diamine glycidyl amine, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N′-diamine glycidylaminomethyl) cyclohexane, etc. Can do.

Among them, the epoxy compound preferably has an epoxy equivalent of 100 to 300 for imparting durability. Specifically, one or two of trimethylolpropane polyglycidyl ether or glycerin triglycidyl ether is used. It is more preferable to use more than one species, and it is more preferable to use trimethylolpropane triglycidyl ether or glycerin triglycidyl ether.

Further, as the epoxy compound, an epoxy compound having a hydrolyzable silyl group can also be used.

Examples of the epoxy compound having a hydrolyzable silyl group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxy. Propylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, and the like can be used.

Moreover, as said crosslinking agent (C), the said epoxy compound is the said epoxy compound with respect to the total amount (mole number) of the said functional group [X] which the said urethane resin (A) and the said polyolefin resin (B) have. The ratio of the amount of epoxy group substance (number of moles) of [the amount of epoxy group substance (number of moles) / total amount of functional group [X] (number of moles)] is in the range of 5/1 to 1/5. It is preferable to use it. This makes it possible to form a heat-seal layer that has a stronger crosslink density when cured by heating or the like, so that deterioration and adhesion of the heat-seal layer are not affected by heat or water (humidity). It is possible to achieve both excellent heat and moisture resistance without causing deterioration of the film and excellent adhesion to various substrates.

The use ratio [the amount of the epoxy group substance / the total amount of the functional group [X]] is preferably in the range of 2/1 to 1/5. It is preferable in order to achieve both good adhesion.

The alkylated methylol melamine resin (c1) and the epoxy compound have a mass ratio [the alkylated methylol melamine resin ( c1) / epoxy compound] = 7/1 to ¼, preferably 5/1 to ¼.
Examples of the crosslinking agent (C) include those other than those described above, for example, 2,2′-bis- (2-oxazoline), 2,2′-methylene-bis- (2-oxazoline), 2,2 ′. -Ethylene-bis- (2-oxazoline), 2,2'-trimethylene-bis- (2-oxazoline), 2,2'-tetramethylene-bis- (2-oxazoline), 2,2'-hexamethylene- Bis- (2-oxazoline), 2,2′-octamethylene-bis- (2-oxazoline), 2,2′-ethylene-bis- (4,4′-dimethyl-2-oxazoline), 2,2 ′ -P-phenylene-bis- (2-oxazoline), 2,2'-m-phenylene-bis- (2-oxazoline), 2,2'-m-phenylene-bis- (4,4'-dimethyl-2) -Oxazoline), bis- (2-oxazolinyl) Cyclohexane) sulfide, bis- (2-oxazolinyl norbornane) sulfide, commercially available products include oxazoline compounds such as Epocross WS-500, WS-700 (Nippon Shokubai Co., Ltd.), poly [phenylenebis (dimethylmethylene) carbodiimide], Poly (methyl-1,3-phenylenecarbodiimide), commercially available products such as Carbodilite V-02, V-04, E-01, E-02 (manufactured by Nisshinbo Co., Ltd.), UCALINK XL-29SE, XL-29MP Carbodiimide compounds such as (Union Carbide Co., Ltd.), tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, hydrogenated And isocyanate monomers such as diphenyl methane diisocyanate, they can also be used various isocyanate compounds such as those obtained by addition reaction dihydric or higher alcohol compounds such as trimethylol propane.
The crosslinking agent (C) is preferably used in the range of 1% by mass to 50% by mass with respect to the total mass of the urethane resin (A) and the polyolefin resin (B). More preferably, it is used in the range of 3% by mass to 30% by mass.

Next, the compound (D) having a primary amino group or hydrazide group and having a molecular weight of 20 to 3,000 used in the present invention will be described.
The compound (D) having a primary amino group or hydrazide group and having a molecular weight of 20 to 3,000 used in the heat sealant of the present invention is used for imparting excellent adhesion to various substrates.
The compound (D) having a primary amino group or hydrazide group and having a molecular weight of 20 to 3,000 is dispersed in an aqueous medium (E) in a state of being blended with the urethane resin (A), the polyolefin resin (B), or the like. Alternatively, it is preferably dissolved. The compound (D) may act as the compound (a3) having the primary amino group or hydrazide group, and a part of the compound (D) may react with a part of the isocyanate group of the urethane resin (A). .
As the compound (D), it is preferable to use a compound having a relatively low molecular weight of 3,000 or less, and using a compound having a molecular weight of 20 to 1,000 increases the crosslinking density and makes it more durable. It is more preferable in improving the property. In addition, the molecular weight of the said compound (D) is a value based on the sum total of the atomic weight of the atom which comprises it.
Examples of the compound (D) include hydrazine, dicarboxylic acid dihydrazide, carbohydrazide, 1,3-bis (hydrazinocarbonoethyl) -5-isopropylhydantoin, ethanolamine, and the like. Hydrazine or dicarboxylic acid can be used. It is preferable to use acid dihydrazide or carbohydrazide, and it is more preferable to use dicarboxylic acid dihydrazide in order to further improve the heat and humidity resistance.
As the dicarboxylic acid dihydrazide, for example, one or two or more of malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, glutaric acid dihydrazide, sebacic acid dihydrazide, isophthalic acid dihydrazide; β-semicarbazide propionic acid hydrazide are used. be able to. Among them, it is preferable to use adipic acid dihydrazide for imparting excellent adhesion.
The compound (D) having the primary amino group or hydrazide group is 0.1% by mass to 20% with respect to 100 parts by mass of the urethane resin (A) from the viewpoint of imparting excellent adhesion to various substrates. It is preferable to use in the range of mass%.

Next, the aqueous medium (E) used in the present invention will be described.
Examples of the aqueous medium (E) used in the present invention include water, an organic solvent miscible with water, and a mixture thereof. Examples of the organic solvent miscible with water include alcohols such as methanol, ethanol, n- and isopropanol; ketones such as acetone and methyl ethyl ketone; polyalkylene glycols such as ethylene glycol, diethylene glycol and propylene glycol; alkyl ethers of polyalkylene glycol; And lactams such as N-methyl-2-pyrrolidone. In the present invention, only water may be used, a mixture of water and an organic solvent miscible with water may be used, or only an organic solvent miscible with water may be used. From the viewpoint of safety and load on the environment, water alone or a mixture of water and an organic solvent miscible with water is preferable, and only water is particularly preferable.

The aqueous medium (E) is contained in the range of 10% by mass to 80% by mass with respect to the total amount of the heat sealant of the present invention, which improves the workability of the heat sealant of the present invention. , It is preferable for achieving both adhesion and heat-and-moisture resistance.

The heat sealing agent of the present invention is, for example, an aqueous dispersion of the urethane resin (A) obtained by the above method, an aqueous dispersion of the polyolefin resin (B), and the crosslinking agent (C), all at once or divided. Can be supplied and mixed. In the crosslinking agent (C), the alkylated methylol melamine resin (c1) and the epoxy compound may be mixed in advance, and these are separately separated into an aqueous dispersion of the urethane resin (A) or the polyolefin resin (B )) Or an aqueous dispersion.

The heat sealing agent of the present invention obtained by the above method may contain other additives as required in addition to the above-described components.

Examples of the additive include an antioxidant, a light-resistant agent, a plasticizer, a film-forming aid, a leveling agent, a foaming agent, a thickener, a colorant, a flame retardant, other aqueous resins, and various fillers. It can be used within a range that does not impair the effect.

Further, as the additive, for example, a surfactant can be used from the viewpoint of further improving the dispersion stability of the heat sealant of the present invention. However, since the surfactant may reduce the adhesion and water resistance of the resulting coating, it is 20 parts by mass or less with respect to 100 parts by mass in total of the urethane resin (A) and the polyolefin resin (B). It is preferable to use within a range, and it is preferable not to use as much as possible.

The heat sealant of the present invention can form a heat seal layer having excellent adhesion to a substrate and excellent heat and moisture resistance. In particular, the heat sealing agent of the present invention has excellent adhesion to both the polar substrate (I) and the nonpolar substrate (II), so the polar substrate (I) and the nonpolar substrate It can be suitably used for a heat sealant for bonding with (II). Specifically, an ethylene-vinyl acetate copolymer, a polyvinylidene fluoride resin, a polyvinyl fluoride resin, an ethylene-vinyl alcohol copolymer that can constitute the opposite side (surface) to the light receiving surface constituting the solar cell. , A non-polar base material composed of polypropylene resin, polyvinyl butyral, glass or the like and a heat sealant for adhesion between a backsheet layer (polar base material) made of polyethylene terephthalate, polypropylene, or the like. .

As a base material which can form the said heat seal layer, various plastics and its film, a metal, glass, paper, wood, etc. are mentioned, for example. Specifically, a polyethylene terephthalate base material etc. are mentioned as a polar base material. Nonpolar substrates include, for example, substrates composed of ethylene-vinyl acetate copolymer, polyvinylidene fluoride resin, polyvinyl fluoride resin, ethylene-vinyl alcohol copolymer, polypropylene resin, polyvinyl butyral, glass, etc. Is mentioned.
The surface of the substrate may be subjected to surface treatment in advance, and specifically, corona treatment is preferably performed. When a reactive group such as a carbonyl group is formed on the surface of the substrate by corona treatment, it forms a bond with the urea bond of the urethane resin (A) contained in the heat sealant of the present invention. It is presumed that the adhesion can be further improved.

In addition, the heat sealing agent of the present invention can be applied to the surface of one substrate and dried by placing the other substrate on the surface of the resin layer that has been crosslinked to some extent and then heating, thereby causing the crosslinking reaction. It can be used when the generated hydroxyl group reacts with the hydrolyzable silyl group of the epoxy compound and the two substrates are bonded together. Since the surface of the resin layer formed by applying and drying on the surface of one of the substrates has almost no tackiness before the heating, the resin layer is previously provided on the surface of one of the substrates. It is also possible to store the stacked members in a stacked state.

On the other hand, when the other base material is placed on the heat seal layer surface in advance on the base material surface and heated, melting and crosslinking reaction of the heat seal layer proceeds, and both base materials are firmly bonded. Is possible. In addition, since the heat seal layer formed after the crosslinking reaction is also excellent in heat and moisture resistance, it is possible to prevent the heat seal layer from being deteriorated due to the influence of heat, water (humidity) or the like.

Examples of the method for applying the heat sealant of the present invention to the substrate surface include a spray method, a curtain coater method, a flow coater method, a roll coater method, a brush coating method, and a dipping method.

In particular, when the heat sealant or the like is applied to the surface of a plastic film such as a polyethylene terephthalate film, the heat is applied to the film surface in the course of biaxial stretching of the plastic substrate at about 200 ° C. An in-line coating method can be employed in which a heat seal layer is formed by applying and drying a sealant, causing a crosslinking reaction, and then stretching the film in the transverse direction.

In addition, when the heat sealant or the like is applied to the surface of a plastic film such as a polyethylene terephthalate film, the plastic film obtained by the biaxial stretching is once wound around a roll or the like, and then from the roll. An off-line coating method in which a plastic film is drawn and the heat sealant or the like is applied to the surface can be employed.

When applying the heat sealant or the like to the surface of the plastic film by the off-line coating method, it is preferable to perform drying at a temperature of approximately 150 ° C. or lower so as not to impair the dimensional stability of the plastic film.

By the above method, a heat seal layer formed by crosslinking and curing of the heat sealant on the substrate surface can be formed.

In addition, when the heat sealing agent of the present invention is applied to one substrate surface as described above, and the heat sealing layer formed by crosslinking and curing the heat sealing agent on the substrate surface is provided, By placing another base material on the surface of the heat seal layer and then heating to approximately 100 ° C. to 160 ° C. in a reduced pressure or pressurized state, a laminated body thereof can be obtained. it can.

Since the laminate is excellent in heat and humidity resistance, it can be used for various purposes including, for example, the production of solar cell modules (solar power generation devices) and the fixing of automobile interior materials. In particular, ethylene-vinyl acetate copolymer, polyvinylidene fluoride resin, polyvinyl fluoride resin, ethylene-vinyl alcohol copolymer, polypropylene resin, which constitutes the opposite side (surface) to the light-receiving surface constituting the solar cell, It can be suitably used for adhesion between a nonpolar substrate made of polyvinyl butyral, glass or the like and a backsheet layer (nonpolar substrate) made of polyethylene terephthalate or polypropylene or the like.

The solar cell module is generally intended to prevent deterioration on the surface of a base material made of an ethylene-vinyl acetate copolymer or the like constituting the surface opposite to the light receiving surface constituting the solar cell. In many cases, a back sheet layer made of polyethylene terephthalate or polypropylene is provided. They are formed, for example, by curing the heat-sealing agent of the present invention on the substrate surface made of the ethylene-vinyl acetate copolymer constituting the surface opposite to the light receiving surface constituting the solar cell. It can be produced by providing a heat seal layer and then laminating a back sheet layer made of polyethylene terephthalate or polypropylene on the heat seal layer.

More specifically, a laminated sheet having a heat seal layer formed by curing the heat seal agent on a sheet surface made of polyethylene terephthalate or polypropylene or the like that can form the back sheet layer is prepared, and a solar cell. The heat seal layer of the laminated sheet and the substrate surface made of the ethylene-vinyl acetate copolymer are in contact with the substrate surface made of the ethylene-vinyl acetate copolymer on the opposite side to the light receiving surface constituting They can be stacked and stacked by heating.

The solar cell module obtained by such a method is excellent in durability such as moisture and heat resistance even when used outdoors for a long period of time.

Hereinafter, the present invention will be specifically described with reference to examples and comparative examples.

[Preparation Example 1]
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, 1000 parts by mass of polyoxytetramethylene glycol (weight average molecular weight: 2,000), 2.2'-diethyl under a nitrogen stream. After adding 79.4 parts by mass of methylolpropionic acid and 884.3 parts by mass of ethyl acetate and mixing uniformly, add 247.2 parts by mass of tolylene diisocyanate, then add 0.1 parts by mass of dibutyltin dilaurate, and add 80 ° C. For about 4 hours to obtain an ethyl acetate solution of a urethane prepolymer having an isocyanate group at the molecular terminal (mass ratio of isocyanate group to the urethane prepolymer (isocyanate group content); 2.1% by mass). .
Next, the ethyl acetate solution of the urethane prepolymer obtained by the above method was cooled to 40 ° C., 65.9 parts by mass of triethylamine was added to neutralize the carboxyl group in the urethane prepolymer, and then ion-exchanged water 2849. Next, 1 part by mass was added, and then 24.6 parts by mass of 80% by mass hydrated hydrazine (hydrazine monohydrate, 80% by mass hydrazine based on the total) was added and reacted.
After completion of the reaction, ethyl acetate was distilled off under reduced pressure, and ion-exchanged water was added so that the non-volatile content was 35% by mass to obtain composition (I).

[Preparation Example 2]
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, 1000 parts by mass of polyoxytetramethylene glycol (weight average molecular weight: 2,000), 2.2'-diethyl under a nitrogen stream. After adding 79.4 parts by mass of methylolpropionic acid and 668.2 parts by mass of ethyl acetate and mixing uniformly, 247.2 parts by mass of tolylene diisocyanate was added, then 0.1 part by mass of dibutyltin dilaurate was added, and Was allowed to react for about 4 hours to obtain an ethyl acetate solution of a urethane prepolymer having an isocyanate group at the molecular end (isocyanate group content; 2.1% by mass).
Then, the ethyl acetate solution of the urethane prepolymer obtained by the above method was cooled to 40 ° C., 65.4 parts by mass of triethylamine was added to neutralize the carboxyl group in the urethane prepolymer, and then ion-exchanged water 3174. 1 part by mass was added, and then 136.9 parts by mass of adipic acid dihydrazide was added and reacted.
After completion of the reaction, ethyl acetate was distilled off under reduced pressure, and ion-exchanged water was added so that the nonvolatile content was 35% by mass, thereby obtaining a composition (II).

[Preparation Example 3]
While introducing a nitrogen gas into a reactor equipped with a thermometer, a nitrogen gas introduction tube, and a stirrer, Poresta VS-1236 (manufactured by Seiko PMC, aqueous dispersion of maleic anhydride-modified polyolefin, weight average molecular weight 70000) 1000 parts by mass, stirred at 80 ° C. for 3 hours to melt, then cooled to 50 ° C., neutralized by adding 180 parts by mass of triethylamine, and then water-solubilized by adding 2153 parts by mass of water, so that the nonvolatile content is 30 parts by mass. % Composition (III) was obtained.

[Preparation Example 4]
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, 1000 parts by mass of polyoxytetramethylene glycol (weight average molecular weight: 2,000), 2.2'-diethyl under a nitrogen stream. After adding 79.4 parts by mass of methylolpropionic acid and 668.2 parts by mass of ethyl acetate and mixing uniformly, 247.2 parts by mass of tolylene diisocyanate was added, then 0.1 part by mass of dibutyltin dilaurate was added, and Was allowed to react for about 4 hours to obtain an ethyl acetate solution of a urethane prepolymer having an isocyanate group at the molecular end (isocyanate group content; 2.1% by mass).
Next, the ethyl acetate solution of the urethane prepolymer obtained by the above method was cooled to 40 ° C., 65.9 parts by mass of triethylamine was added to neutralize the carboxyl group in the urethane prepolymer, and then ion-exchanged water 3111. 0 parts by mass was added, and then 70.8 parts by mass of carbohydrazide was added and reacted.
After completion of the reaction, ethyl acetate was distilled off under reduced pressure, and ion-exchanged water was added so that the nonvolatile content was 35% by mass, thereby obtaining a composition (IV).

[Preparation Example 5]
In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen blowing tube, 1000 parts by mass of polyoxytetramethylene glycol (weight average molecular weight: 2,000), 2.2'-diethyl under a nitrogen stream. After adding 79.4 parts by mass of methylolpropionic acid and 884.3 parts by mass of ethyl acetate and mixing uniformly, add 247.2 parts by mass of tolylene diisocyanate, then add 0.1 parts by mass of dibutyltin dilaurate, and add 80 ° C. For about 4 hours to obtain an ethyl acetate solution of a urethane prepolymer having an isocyanate group at the molecular terminal (mass ratio of isocyanate group to the urethane prepolymer (isocyanate group content); 2.1% by mass). .
Next, the ethyl acetate solution of the urethane prepolymer obtained by the above method was cooled to 40 ° C., 65.9 parts by mass of triethylamine was added to neutralize the carboxyl group in the urethane prepolymer, and then ion-exchanged water 2849. Next, 1 part by mass was added, and then 18.5 parts by mass of 80% by mass hydrated hydrazine (hydrazine monohydrate, 80% by mass hydrazine based on the total) was added and reacted.
After completion of the reaction, ethyl acetate was distilled off under reduced pressure, and ion-exchanged water was added so that the nonvolatile content was 35% by mass to obtain a composition (V).

[Adjustment Example 6]
While introducing nitrogen gas in a reactor equipped with a thermometer, a nitrogen gas inlet tube, and a stirrer, 830 parts by mass of terephthalic acid, 830 parts by mass of isophthalic acid, 374 parts by mass of ethylene glycol, 604 parts by mass of neopentyl glycol and dibutyltin After 0.5 parts by mass of oxide was charged and esterified at 180 to 230 ° C. for 5 hours, a polycondensation reaction was carried out at 260 ° C. for 6 hours until the acid value was less than 1, whereby an acid value of 0.2 and a hydroxyl value of 74. 5 polyester polyol (a1 ′) was obtained.
After dehydrating 1000 parts by mass of the polyester polyol (a1 ′) at 100 ° C. under reduced pressure, cooling to 80 ° C., adding 690 parts by mass of methyl ethyl ketone, sufficiently stirring and dissolving, 77 parts by mass of 2,2′-dimethylolpropionic acid. Then, 209 parts by mass of hexamethylene diisocyanate was further added and reacted at 75 ° C. for 8 hours.
After confirming that the mass ratio of unreacted isocyanate groups remaining in the reaction mixture became 0.1 mass% or less, the mixture was cooled to 50 ° C., 58 parts by mass of triethylamine and 5100 parts by mass of water were added, and the pressure was reduced. Then, methyl ethyl ketone was removed at a temperature of 40 to 60 ° C., and the concentration was adjusted by adding water to obtain a composition (VI) having a nonvolatile content of 20% by mass in which an aqueous urethane resin was dispersed in water.

[Example 1]
100 parts by mass of the composition (I) obtained in Preparation Example 1 and 78 parts by mass of the composition (III) obtained in Preparation Example 3 were mixed. Next, 5 parts by weight of Becamine M-3 (manufactured by DIC Corporation, trimethoxymethylol type melamine resin, non-volatile content 80% by mass) and Denacol EX-321 (manufactured by Nagase ChemteX Corporation, trimethylolpropane triglycidyl ether, non-volatile content 100 parts by mass) and 4 parts by mass, and 3 parts by weight of adipic acid dihydrazide (molecular weight 174.2) and water were added to the aqueous resin composition (X-1) having a nonvolatile content of 20% by mass. A heat sealant (X-1) was obtained.

[Example 2]
An aqueous resin composition was prepared in the same manner as in Example 1 except that 100 parts by mass of the composition (II) obtained in Preparation Example 2 was used instead of 100 parts by mass of the composition (I) obtained in Preparation Example 1. A heat sealant (X-2) comprising the product (X-2) was obtained.

[Example 3]
Except for changing the amount of Becamine M-3 (trimethoxymethylol type melamine resin manufactured by DIC Corporation, non-volatile content 80% by mass) from 5 parts by mass to 23 parts by mass, the same method as in Example 1 was used. A heat sealant (X-3) comprising the aqueous resin composition (X-3) was obtained.

[Example 4]
The same method as in Example 1 except that the amount of Denacol EX-321 (manufactured by Nagase ChemteX Corporation, trimethylolpropane triglycidyl ether, non-volatile content 100% by mass) was changed from 4 parts by mass to 42 parts by mass To obtain a heat sealant (X-4) comprising the aqueous resin composition (X-4).

[Example 5]
The same method as in Example 1 except that the amount of Denacol EX-321 (manufactured by Nagase ChemteX Corporation, trimethylolpropane triglycidyl ether, non-volatile content: 100% by mass) was changed from 4 parts by mass to 1 part by mass To obtain a heat sealant (X-5) comprising the aqueous resin composition (X-5).

[Example 6]
The amount of the composition (III) described in Preparation Example 3 was changed from 78 parts by mass to 175 parts by mass, and Beccamin M-3 (a trimethoxymethylol melamine resin manufactured by DIC Corporation, nonvolatile content 80% by mass) was used. The usage amount was changed from 5 parts by mass to 7 parts by mass, and the usage amount of Denacol EX-321 (manufactured by Nagase ChemteX Corporation, trimethylolpropane triglycidyl ether, nonvolatile content 100% by mass) was changed from 4 parts by mass. The heat sealant (X-6) comprising the aqueous resin composition (X-6) was prepared in the same manner as in Example 1 except that the amount was changed to 8 parts by mass and the amount of adipic acid dihydrazide (molecular weight 174.2) was changed to 4 parts by weight. -6) was obtained.

[Example 7]
Instead of Becamine M-3 (DIC Corporation, trimethoxymethylol type melamine resin, non-volatile content 80% by mass), Becamine J-101 (DIC Corporation, hexamethoxymethylol type melamine resin, non-volatile content 80% by mass) A heat sealant (X-7) composed of the aqueous resin composition (X-7) was obtained in the same manner as in Example 1 except that 5 parts by mass of was used.

[Example 8]
An aqueous resin composition was prepared in the same manner as in Example 1 except that 100 parts by mass of the composition (IV) obtained in Preparation Example 4 was used instead of 100 parts by mass of the composition (I) obtained in Preparation Example 1. Heat sealant (X-8) consisting of product (X-8) was obtained.

[Example 9]
An aqueous resin composition was prepared in the same manner as in Example 1 except that 100 parts by mass of the composition (V) obtained in Preparation Example 5 was used instead of 100 parts by mass of the composition (I) obtained in Preparation Example 1. Heat sealant (X-9) consisting of product (X-9) was obtained.

[Example 10]
An aqueous resin composition was prepared in the same manner as in Example 1 except that 100 parts by mass of the composition (VI) obtained in Preparation Example 6 was used instead of 100 parts by mass of the composition (I) obtained in Preparation Example 1. Heat sealant (X-10) comprising product (X-10) was obtained.

[Comparative Example 1]
100 parts by mass of the composition (I) obtained in Preparation Example 1 and 78 parts by mass of the composition (III) obtained in Preparation Example 3 were mixed and stirred, and water was added thereto to add an aqueous solution having a nonvolatile content of 20% by mass. A heat sealant (X′-1) comprising the resin composition (X′-1) was obtained.

[Comparative Example 2]
100 parts by mass of the composition (III) obtained in Preparation Example 3, 2 parts by mass of Becamine M-3 (a trimethoxymethylol-type melamine resin manufactured by DIC Corporation, non-volatile content 80% by mass), and Denacol EX-321 (Nagase) 4 parts by mass of Chemtex Co., Ltd., trimethylolpropane triglycidyl ether (non-volatile content: 100% by mass) was added, stirred, and water added to add an aqueous resin composition (X′-2) having a non-volatile content of 20% by mass. A heat sealant (X′-2) consisting of

[Comparative Example 3]
5 parts by weight of becamine M-3 (manufactured by DIC Corporation, trimethoxymethylol type melamine resin, nonvolatile content 80% by mass) and Denacol EX-321 (manufactured by Nagase ChemteX Corporation, trimethylolpropane triglycidyl ether, nonvolatile content 100 masses) %) Aqueous resin composition in the same manner as in Example 1 except that Chemitite PZ-33 (manufactured by Nippon Shokubai Co., Ltd., polyfunctional aziridine, non-volatile content 100% by mass) was used instead of 4 parts by mass. A heat sealant (X′-3) comprising the product (X′-3) was obtained.

[Comparative Example 4]
Instead of 100 parts by mass of the composition (I) obtained in Preparation Example 1, 100 parts by weight of the composition (VI) obtained in Preparation Example 6 was used in the same manner as in Comparative Example 3, except that the aqueous resin composition was used. A heat sealant (X′-4) comprising the product (X′-4) was obtained.

[Method for evaluating adhesion to polar and non-polar substrates]
The surface of the polyethylene terephthalate film, which is a polar substrate, is coated with the heat sealant obtained in the examples and comparative examples so that the dry film thickness is 5 μm, and is dried at 150 ° C. for 5 minutes. A laminate having a cured resin layer (heat seal layer) crosslinked on the film surface was obtained.

On the surface of the cured resin layer (heat seal layer) of the laminate, a film (length: 5 cm × width: 1 cm) made of ethylene-vinyl acetate as a nonpolar base material is placed, and then a vacuum pressure bonding apparatus is used for 150. By crimping them at 15 ° C. for 15 minutes, a laminate in which a polyethylene terephthalate film and a polyolefin film were bonded via the resin cured layer (heat seal layer) was obtained.

[Adhesion test method]
The adhesion of the laminate immediately after being produced by the above method was evaluated by a T-type peel test (1000 N cell) using a tensile tester (manufactured by Shimadzu Corporation). The adhesion was evaluated based on the adhesion between the heat seal layer and the ethylene-vinyl acetate film.

When the peel strength measured by the above method was approximately 30 N / cm or more, the adhesion was evaluated as excellent, and when the peel strength was 35 N / cm or more, the adhesion was evaluated as particularly excellent.

[Evaluation of heat and humidity resistance]
The laminate obtained above was left in a constant temperature and humidity chamber set at 120 ° C. × 100% RH for 72 hours to perform a wet heat test. The adhesion of the laminate after standing was measured and evaluated by the same method as described above.

When the peel strength measured by the above method was approximately 25 N / cm or more, the adhesion was evaluated as excellent, and when the peel strength was 35 N / cm or more, the adhesion was evaluated as particularly excellent.

[Observation of peeled interface (after wet heat test)]
The laminate obtained above was left in a constant temperature and humidity chamber set at 121 ° C. × 100% RH for 72 hours to perform a wet heat test.
The peel interface of the laminate after the wet heat test was visually observed. As a result, the film itself made of ethylene-vinyl acetate was evaluated as “A” when the film was broken by cohesive failure, and the film and the above-mentioned film was evaluated as “B” when the heat sealant layer was broken by cohesive failure. The layer was not broken, and the film where the film made of ethylene-vinyl acetate and the heat sealant layer were peeled off was evaluated as “C”. Both the film and the layer were not broken, and the polyethylene terephthalate film And “D” were evaluated as those where interfacial peeling occurred between the heat sealant layer and the heat sealant layer. Those evaluated as A to C can be used practically, and those evaluated as A to B can be preferably used when higher level characteristics are required.

“Content of alkylated methylol melamine resin (c1) [% by mass]” in Tables 1 to 3 represents a mass ratio of the alkylated methylol melamine resin to the total mass of the urethane resin and the polyolefin resin.
In the table, “M-3” represents Becamine M-3 (trimethoxymethylol type melamine resin manufactured by DIC Corporation, non-volatile content 80% by mass), and “EX-321” represents Denacol EX-321 ( Represents a product of Nagase ChemteX Corporation, trimethylolpropane triglycidyl ether, non-volatile content of 100% by mass. “J-101” represents Becamine J-101 (DIC Corporation, hexamethoxymethylol-type melamine resin, non-volatile content of 80 mass). “PZ-33” represents Chemitite PZ-33 (manufactured by Nippon Shokubai Co., Ltd., polyfunctional aziridine, nonvolatile content 100 mass%).

Claims (9)

1. Cross-linking agent (C) containing at least one selected from the group consisting of urethane resin (A), polyolefin resin (B), melamine compound, epoxy compound, oxazoline compound, carbodiimide compound and isocyanate compound, and primary amino group Alternatively, a heat sealant comprising a compound (D) having a hydrazide group and a molecular weight of 20 to 3,000, and an aqueous medium (E).
2. The heat sealant according to claim 1, wherein the compound (D) is hydrazine, dicarboxylic acid dihydrazide or carbohydrazide.
3. The cross-linking agent (C) contains an alkylated methylol melamine resin (c1) as an melamine compound and an epoxy compound (c2), and one of the urethane resin (A) and the polyolefin resin (B). Or both have the functional group [X] which can react with an epoxy group, The heat seal agent of Claim 1 characterized by the above-mentioned.
4. The alkylated methylol melamine resin (c1) is included in the range of 5% by mass to 50% by mass with respect to the total mass of the urethane resin (A) and the polyolefin resin (B), and the urethane resin (A) and Ratio of the substance amount of the epoxy group of the epoxy compound (c2) to the total substance amount of the functional group [X] possessed by one or both of the polyolefin resin (B) [substance quantity of epoxy group / functional group [X The heat sealing agent according to claim 3, wherein the total amount of the substance] is 5/1 to 1/5.
5. A heat seal layer formed by applying and drying the heat sealant according to any one of claims 1 to 4 is provided on the surface of the polar substrate (I), and the surface of the heat seal layer is non-polar. A laminate obtained by placing the substrate (II) and then heating at 80 ° C. to 180 ° C.
6. The polar substrate (I) is a polyethylene terephthalate substrate, a polypropylene substrate, a polycarbonate substrate or a polyamide substrate, and the nonpolar substrate (II) is a substrate made of an ethylene-vinyl acetate copolymer. The laminate according to claim 5.
7. Either one of the urethane resin (A) and the polyolefin resin (B) is obtained by applying the heat sealant according to any one of claims 1 to 4 to the surface of the polar substrate (I) and drying it. Alternatively, the functional group [X] possessed by both reacts with the epoxy group possessed by the epoxy compound (c2),
   A self-crosslinking reaction of the alkylated methylolmelamine resin (c1),
   And / or
   A heat seal layer is provided by advancing the reaction between the hydroxyl group generated by the reaction between the functional group [X] and the epoxy compound (c2) and the alkylated methylol melamine resin (c1), and then the heat seal layer. Lamination characterized by adhering the polar substrate (I) and the nonpolar substrate (II) by placing the nonpolar substrate (II) on the surface and then heating at 80 ° C. to 180 ° C. Body manufacturing method.
8. The heat sealant according to any one of claims 1 to 4 is formed on the surface of a base material made of an ethylene-vinyl acetate copolymer, on the opposite side to the light receiving surface constituting the solar cell. And a back sheet layer made of a polyethylene terephthalate base material, a polypropylene base material, a polycarbonate base material, or a polyamide base material on the heat seal layer.
9. A heat seal layer formed using the heat seal agent according to any one of claims 1 to 4 is provided on a sheet surface comprising a polyethylene terephthalate base material, a polypropylene base material, a polycarbonate base material, or a polyamide base material. Laminated sheet,
   On the surface of the substrate made of an ethylene-vinyl acetate copolymer constituting the surface opposite to the light receiving surface constituting the solar cell,
   A method for producing a solar cell module, wherein the heat sealing layer of the laminated sheet and the substrate surface made of the ethylene-vinyl acetate copolymer are placed in contact with each other and heated.