JP7047353B2 - Adhesive composition for forming laminated sheets - Google Patents

Description

The present invention relates to an adhesive composition for forming a laminated sheet used for adhering a plastic film, a metal foil, or the like.

In recent years, aluminum has been used as a multi-layer (composite) sheet for outdoor industrial applications, for example, for barrier materials, roofing materials, solar cell panel materials, window materials, outdoor flooring materials, lighting protection materials, automobile parts, signs, stickers, etc. A metal foil such as copper or steel plate, a metal plate, or a metal vapor deposition film and a plastic film such as polypropylene, polyvinyl chloride, polyester, fluororesin, or acrylic resin are laminated to form a laminated film. Things have been used. An epoxy-based adhesive composition or a polyurethane-based adhesive composition is known as an adhesive composition for bonding a metal foil, a metal plate, or a metal vapor-deposited film and a plastic film in these multilayer films. ..

Patent Document 1 describes an adhesive composition for forming a composite laminated film for food packaging materials, which contains a polyester polyurethane polyol, a polyester resin containing a carboxyl group at the molecular terminal, a phosphoric acid-modified epoxy resin, and an isocyanate compound. It is disclosed that after the films are laminated, they are aged at 40 ° C. for 4 days to cure the adhesive composition (claim 1, [0001], [0041]).

Patent Document 2 describes that a polyurethane-based adhesive composition having hydrolysis resistance is used in a sheet for sealing the back surface of a solar cell, and after the films are overlapped with each other, they are aged at 50 ° C. for 5 days. There is.

Patent Document 3 describes aging of a laminate for flexible packaging of foods and the like, which can withstand retort treatment and exhibits sufficient adhesive strength at 40 to 60 ° C. for about 4 to 5 days. Although a period was required until then ([0001], [0007]), an adhesive capable of exhibiting performance comparable to that of the conventional aging time even if the aging time was shortened to about one day was disclosed. ([097], [0106]).

Japanese Unexamined Patent Publication No. 06-116542 Japanese Unexamined Patent Publication No. 2008-4691 International release 2006/118786

When forming a laminate for flexible packaging of foods and the like as described in Patent Document 3, the aging time can be shortened to about one day.
However, unlike the laminate for flexible packaging of foods and the like, in the case of a laminate that is exposed to the outdoors for a long time such as a sheet for sealing the back surface of a solar cell, the adhesive described in Patent Document 3 is resistant to hydrolysis. Due to insufficient properties, there has been a problem that the adhesive strength is significantly reduced depending on the accelerated test environment.
The present invention relates to an adhesive composition capable of maintaining adhesive strength for a long period of time even when the aging time is shortened and even in the case of a laminated body exposed to the outdoors for a long time such as a sheet for sealing the back surface of a solar cell. It is an object of the present invention to provide a laminated body using it.

As a result of diligent studies to solve the above problems, the present inventors have found that the above object can be achieved by the adhesive composition for forming a laminated sheet shown below, and complete the following inventions [1] to [6]. I came to do.

[1] An adhesive composition for forming a laminated sheet, which comprises a polyester-based polyol (A) which is a reaction product of a carboxylic acid component and a hydroxyl group component and a polyisocyanate compound (B).
At least one of the carboxylic acid component and the hydroxyl group component contains a monofunctional component _, and at least one of the carboxylic acid component and the hydroxyl group component contains a trifunctional or higher functional component.
The polyester-based polyol (A) has a hydroxyl value of 15 to 40 mg / KOH, an acid value of at most 0.5 mg / KOH, and a branching degree α measured by GPC-MALS-VISCO of 0.6 or less. An adhesive composition for forming a laminated sheet, which is characterized by being.

[2] In a total of 200 mol% of the carboxylic acid component and the hydroxyl group component,
The adhesive composition for forming a laminated sheet according to the above [1], wherein the monofunctional component is 0.2 to 8 mol%, and the trifunctional or higher component is 0.2 to 8 mol%.

[3] The polyester-based polyol (A) measured by GPC-RI is characterized in that the number average molecular weight (Mn) is 2000 to 20000 and the molecular weight distribution (Mw / Mn) is 2.5 to 10. The adhesive composition for forming a laminated sheet according to the above [1] or [2].

[4] The adhesive composition for forming a laminated sheet according to any one of the above [1] to [3], wherein the glass transition temperature of the polyester-based polyol (A) is −35 to 15 ° C.

[5] The adhesive composition for forming a laminated sheet according to any one of the above [1] to [4], wherein the polyisocyanate compound (B) is an aliphatic polyisocyanate compound (B-1). thing.

[6] A laminated sheet using the adhesive composition for forming a laminated sheet according to any one of the above [1] to [5].

By using the adhesive composition for forming a laminated sheet of the present invention as an adhesive for a laminated sheet, the adhesive strength can be maintained for a long period of time even if the cross-linking reaction between the polyester-based polyol and the polyisocyanate compound is shortened. .. This makes it possible to provide a sheet for sealing the back surface of a solar cell having a short production process.

Hereinafter, preferred embodiments of the present invention will be described.
The adhesive composition for forming a laminated sheet according to the present invention is characterized by containing a polyester-based polyol (A) and a polyisocyanate compound (B). Details will be described below.

≪Polyester-based polyol (A) ≫

It is important that the polyester-based polyol (A) used in the adhesive composition for forming a laminated sheet of the present invention has a hydroxyl value of 15 to 40 mg / KOH, and preferably 25 to 35 mg / KOH. The hydroxyl group is used in a crosslinking reaction with the polyisocyanate compound (B) described later, and as the crosslinking reaction proceeds, the adhesive has a higher molecular weight and hydrolysis resistance can be enhanced. When the hydroxyl value is 15 mg / KOH or more, the reaction with the polyisocyanate compound (B) is likely to proceed, the crosslinking reaction proceeds rapidly, the crosslinking becomes dense, and the hydrolysis resistance is improved. On the other hand, when the hydroxyl value is 40 mg / KOH or less, excessive cross-linking can be suppressed and the adhesiveness to the substrate can be improved.

The hydroxyl value of the polyester-based polyol (A) can be obtained, for example, by the same method as described in International Publication 2006/117886.

It is important that the polyester-based polyol (A) in the present invention has an acid value as low as possible, and specifically, it is important that the acid value is at most 0.5 mgKOH / g. By using the polyester-based polyol (A) having an acid value of 0.5 mgKOH / g or less, the water absorption of the formed adhesive can be suppressed and the hydrolysis can be suppressed. As a result, the durability as a laminated sheet is improved.

The acid value of the polyester-based polyol (A) can be determined by, for example, the neutralization titration method described in JIS K 0070-1992.

Further, it is important that the polyester-based polyol (A) in the present invention has a branching degree α measured by GPC-MALS-VISCO of 0.6 or less. GPC-MALS-VISCO is a GPC (gel permeation chromatography) in which a multi-angle light scattering detector and a viscosity detector are connected, and it is possible to measure the absolute molecular weight and the degree of branching α.
The smaller the degree of branching α, the more the polymer has a branched structure. When the degree of branching α is 0.6 or less, a polymer having a low viscosity can be obtained by introducing the branched structure. By lowering the viscosity of the polymer, the wettability to the substrate is increased and the adhesiveness is improved. By lowering the viscosity of the polymer, the cross-linking reaction can easily proceed, the cross-linking density can be improved, and the hydrolysis resistance can be improved.
The degree of branching α can be calculated from the following Mark-Houwink-Sakurada equation.
[η] = KM ^α
log [η] ＝ log [K] ＋ αlog [M]
In the formula, [η] is the ultimate viscosity, K is a constant, and M is the absolute molecular weight.

The polyester-based polyol (A) in the present invention is a reaction product of a carboxylic acid component and a hydroxyl group component, and the raw materials for forming a main chain are mainly composed of bifunctional components, respectively, and the carboxylic acid component and the above-mentioned It is important that at least one of the hydroxyl group components contains a monofunctional component and a trifunctional or higher functional component. In a total of 200 mol% of the carboxylic acid component and the hydroxyl group component for forming the main chain, 0.2 to 8 mol% of the monofunctional component and 0.2 to 8 mol% of the trifunctional or higher component are contained. Is preferable.
By using a trifunctional or higher component, a branched structure can be introduced and the above-mentioned effects can be obtained. However, on the other hand, if the trifunctional component is used and the monofunctional component is not used, high molecular weight and gelation are likely to occur during the synthesis of the polyester-based polyol, and the difficulty of the synthesis becomes high. Therefore, by using a monofunctional component in combination, it is possible to suppress the increase in molecular weight and gelation.

By the way, Patent Document 3 describes an adhesive containing a partially acid-modified polyester alcohol composition and a polyisocyanate, and as raw materials for the partially acid-modified polyester alcohol composition, monofunctional components, trimellitic anhydride and the like are described. The use of trifunctional or higher functional carboxylic acid components is disclosed.
However, trimellitic anhydride and the like in Patent Document 3 are not raw materials for forming the main chain of the polyester-based polyol as supported by the expression "partially acid modification", but are not the raw materials for forming the main chain of the polyester-based polyol, but the terminal of the formed main chain. This is for modifying a part of the hydroxyl group. As a result of "partial acid denaturation" with trimellitic anhydride or the like, in the case of Patent Document 3, a carboxyl group is introduced with branching at a part of the terminal of the main component of the adhesive.
Therefore, in the case of Patent Document 3, since the branching position is limited to the end of the polymer main chain, the degree of branching α is large unlike the case of the present invention. In addition, the acid value is also higher than that in the case of the present invention. Even if the acid value is not a problem for food packaging laminates, it is possible to maintain adhesive strength for a long period of time in the case of laminates that are exposed to the outdoors for a long time, such as solar cell backside sealing sheets. I can't do it.
In the polyester-based polyol (A) in the present invention, when forming the main chain, in addition to the bifunctional component, a monofunctional component and a trifunctional or higher component are used in combination to reduce the degree of branching α and the acid value. Is different from Patent Document 3 in that is as small as possible.

Among the carboxylic acid components constituting such a polyester-based polyol (A), the bifunctional carboxylic acid components include isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, phthalic anhydride, adipic acid, azelaic acid, and sebacic acid. Examples thereof include compounds such as succinic acid, glutaric acid, tetrahydrophthalic acid anhydride, hexahydrophthalic acid anhydride, maleic acid anhydride, itaconic acid anhydride, dimer acid and ester compounds thereof.

Among the carboxylic acid components constituting the polyester-based polyol (A), the monofunctional acid components include, for example, octyl acid, stearic acid, benzoic acid, t-butyl benzoic acid, myristic acid, palmitic acid, stearic acid, and olein. Acids, linoleic acid, linolenic acid and the like can be mentioned.

Among the carboxylic acid components constituting the polyester-based polyol (A), the trifunctional or higher functional acid components include trimellitic acid, pyromellitic acid, 3,3', 4,4'-biphenylsulfonetetracarboxylic acid, and bis. (Triphenylphthalic acid) -4,4'-diphenylmethane anhydride, 9,9-bis (3,4-dicarboxyphenyl) fluorenic acid, trimeric acid and polybasic acid anhydrides such as these anhydrides can be mentioned. ..

Among the hydroxyl group components constituting the polyester-based polyol (A), the bifunctional hydroxyl group components include, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,6-hexanediol, and neopentyl glycol. , 1,4-Butanediol, 1,4-Cyclohexanedimethanol, 1,9-nonanediol, or divalent alcohols such as 3-methyl-1,5-pentanediol.

Among the hydroxyl group components constituting the polyester-based polyol (A), examples of the monofunctional hydroxyl group component include octyl alcohol, lauryl alcohol, myristyl alcohol, stearyl alcohol and the like.

Among the hydroxyl group components constituting the polyester-based polyol (A), examples of the trifunctional or higher functional hydroxyl group component include three or more alcohols such as glycerin, trimethylolpropane, and pentaerythritol.

As described above, it is important that the acid value of the polyester-based polyol (A) is as small as possible. Therefore, when forming the polyester-based polyol (A), it is appropriate that the hydroxyl group component is excessive with respect to the acidic content. Specifically, the functional group is preferably about 1.1 to 1.2 times.

The polyester-based polyol (A) is a polyester polyurethane obtained by further reacting (urethane-modified) a polyisocyanate compound with the hydroxyl group in the reaction product of the carboxylic acid component and the hydroxyl group component under the condition that the hydroxyl group remains. Polyols can also be used.

The polyisocyanate used for obtaining a polyester polyurethane polyol will be described.
As the polyisocyanate used for urethane modification, an aliphatic diisocyanate, an alicyclic diisocyanate, an aromatic diisocyanate, an aromatic aliphatic diisocyanate, a trifunctional or higher polyisocyanate monomer, and various derivatives derived from the diisocyanate can be used. can.

Examples of the aliphatic diisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-petitylene diisocyanate, 2,3-butylenediocyanate, and 1,3-butylenedi isocyanate, 2 , 4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl caproate and the like.

Examples of the alicyclic diisocyanate include 1,4-cyclohexanediisocyanate, 1,3-cyclohexanediisocyanate, 3-isocyanatemethyl-3,5,5-trimethylcyclohexylisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), and methyl. Examples thereof include -2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 1,4-bis (isocyanatemethyl) cyclohexane, and 1,3-bis (isocyanatemethyl) cyclohexane.

Examples of the aromatic diisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalenedi isocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6- Examples thereof include toluene diisocyanate or a mixture thereof, 4,4'-toluene diisocyanate, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate and the like.

Examples of the aromatic diisocyanate containing an aromatic ring include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω, ω'-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4-. Examples thereof include bis (1-isocyanate-1-methylethyl) benzene or a mixture thereof.

Examples of the trifunctional or higher functional polyisocyanate monomer include triphenylmethane-4,4', 4 "-triisocyanate, 1,3,5-triisocyanatebenzene, 2,4,6-triisocyanate toluene and the like. Triisocyanates; tetraisocyanates such as 4,4'-diphenyldimethylmethane-2,2'-5,5'-tetraisocyanate and the like can be mentioned.

Examples of the various derivatives derived from the diisocyanate include the diisocyanate, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and the like. Additions to low molecular weight polyols with a molecular weight of less than 200, such as 3,3'-dimethylolpropane, cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, and sorbitol, ( Adduct body) An adduct (adduct body) such as with castor oil can also be used.
As various derivatives derived from the diisocyanate, in addition to the trimer (also referred to as trimer or nurate) of the diisocyanate, the biuret or the allophanate, 2,4,6-oxa obtained from carbon dioxide and the diisocyanate. A polyisocyanate having a diazintrion ring or the like can also be used.

The urethane modification for obtaining the polyester polyurethane polyol is preferably carried out in a temperature range of 200 ° C. or lower, preferably 120 to 180 ° C.
At the time of urethane modification, it is preferable that the polyester-based polyol and the polyisocyanate are reacted at a ratio such that the isocyanate group of the polyisocyanate has an equivalent ratio of 0.5 or less with respect to the hydroxyl group in the polyester-based polyol. The reaction is more preferably 0.1 to 0.3, still more preferably 0.15 to 0.2 equivalent ratio.

The number average molecular weight (Mn) of the polyester-based polyol (A) in the present invention is 2,000 or more from the viewpoint of increasing the initial cohesive force of the formed adhesive layer and effectively suppressing the occurrence of tunneling during laminating. It is preferably 8,000 or more, and more preferably 8,000 or more. Further, the number average molecular weight of the polyester-based polyol (A) is preferably 20,000 or less, preferably 15,000 or less, from the viewpoint of improving the solubility in a solvent and improving the coatability of the adhesive. It is more preferable to have.
Further, the molecular weight distribution (Mw / Mn) of the polyester-based polyol (A) is preferably 2.5 to 10 from the viewpoint of adhesiveness. When the molecular weight distribution is 10 or less, the solubility in a solvent is high, the storage stability is improved, and the coating viscosity can be easily controlled.
The number average molecular weight (Mn) and the molecular weight distribution (Mw / Mn) referred to here are obtained by GPC-RI. The GPC-RI is a GPC connected to a differential refractive index detector, and obtains a relative molecular weight or the like with respect to standard polystyrene having a known molecular weight.

Further, the glass transition temperature (Tg) of the polyester-based polyol (A) is preferably −35 to 15 ° C. When the Tg is −35 ° C. or higher, the cohesive force of the formed adhesive layer is improved and the adhesive strength is improved. Further, when the Tg is 15 ° C. or lower, the affinity to the substrate is enhanced even at the time of laminating, and the adhesive strength after aging is also improved.

<Polyisocyanate compound (B)>
Next, the polyisocyanate compound (B) will be described.
The polyisocyanate compound (B) has a role of improving the molecular weight of the adhesive layer and improving the internal cohesive force that develops energy elasticity when forming a laminated sheet by cross-linking with the hydroxyl group in the polyester-based polyol (A). have.
Further, the polyisocyanate compound (B) can also be expected to have an effect of improving the interaction with the surface of the substrate, which will be described later. Furthermore, for a substrate that has undergone physical treatment such as corona discharge treatment or chemical treatment modified with an acid or the like, the reactive functional group in the polyisocyanate compound (B) is chemically reacted with the substrate. Therefore, it is also possible to develop a strong interaction between the polyester-based polyol (A) and the base material.
In this way, by using the polyisocyanate compound (B), it is possible to form a strong adhesive layer, and the adhesive layer suppresses the expansion and contraction movement of the base material due to sudden environmental changes, and the adhesive strength is increased. It will be possible to maintain at a high level.
Further, in the present invention, in addition to the polyisocyanate compound (B), an N-methylol group-containing compound, a polyfunctional aziridine compound, a metal chelate compound and the like can also be used.

As the polyisocyanate compound (B), the polyisocyanate derived from the above-mentioned diisocyanate can be preferably used. That is, a nurate form of the diisocyanate, an adduct body in which trimethylolpropane is added to the diisocyanate, a biuret type, a prepolymer having an isocyanate residue (a low polymer obtained from diisocyanate and a polyol), a uretdione body having an isocyanate residue, and the like. Examples thereof include an allophanate form or a complex thereof, and these can be used alone or in combination of two or more.
Above all, when it is also used for outdoor use, it is preferable to use an aliphatic or alicyclic isocyanate or a derivative thereof for the purpose of reducing yellowing over time. Among them, it is preferable to use an aliphatic polyisocyanate, and it is particularly preferable to use a derivative of hexamethylene diisocyanate.

The isocyanate group concentration in the polyisocyanate compound (B) is preferably 10 to 30% by mass, more preferably 11 to 25% by mass. The isocyanate group concentration in the polyisocyanate compound (B) can be determined by a titration method.

The amount of the polyisocyanate compound (B) used is preferably 5 to 25 parts by mass, more preferably 7 to 20 parts by mass with respect to 100 parts by mass of the polyester-based polyol (A). When the amount is 5 parts by mass or more, it is possible to suppress a decrease in the adhesive force after indoor / outdoor exposure, and when the amount is 25 parts by mass or less, the initial adhesive force can be improved.

<Adhesive composition for forming laminated sheets>
The adhesive composition for forming a laminated sheet of the present invention is a so-called two-component mixed type adhesive in which a polyester-based polyol (A) as a main agent and a polyisocyanate compound (B) as a curing agent are mixed at the time of use. Further, it may be a type in which a plurality of main agents and / or a plurality of polyisocyanate compounds are mixed at the time of use. Usually, when used as a two-component mixed type, the first solution contains a polyester-based polyol (A), an organic solvent and, if necessary, the additives described below, and the second solution is a polyisocyanate compound (B). ), In addition to organic solvents, other additives as needed.

<Additives>
The adhesive composition for forming a laminated sheet of the present invention is an epoxy as a resin that reacts with a carboxyl group generated by hydrolysis of an ester bond in a polyester-based polyol (A) from the viewpoint of adhesiveness and hydrolysis resistance. It is preferable to contain a resin. Epoxy resin has the effect of improving moisture and heat resistance.

The epoxy resin is not limited to the following, but is not limited to the following, but is limited to bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol full orange diglycidyl ether, bisphenol full orange glycidyl. Ether, bisphenoxyethanol full orange glycidyl ether, glycerol triglycidyl ether, glycerol diglycidyl ether, polyglycerol polyglycidyl ether, 1,6-butanediol diglycidyl ether, bisphenol A diglycidyl ether, propylene oxide modified bisphenol A diglycidyl ether, Examples thereof include bisphenol F diglycidyl ether, epichlorohydrin-modified phthalic acid, epichlorohydrin-modified hexahydrophthalic acid, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and the like. , Or two or more types can be used.

Among the epoxy resins, an epoxy resin having a number average molecular weight of 300 to 5,000 is preferable from the viewpoint of adhesive strength and moisture heat resistance, and the blending amount of the epoxy resin is 100 mass of polyol (A) from the viewpoint of adhesive strength and moisture heat resistance. 5 to 50 parts by mass is preferable with respect to the part. More preferably, it is 10 to 20 parts by mass. When the amount is 5 parts by mass or more, the moisture and heat resistance can be effectively improved, and when the amount is 50 parts by mass or less, the hardness of the adhesive layer can be appropriately softened and sufficient adhesiveness can be exhibited.

When the adhesive composition for forming a laminated sheet of the present invention uses a metal foil, a metal plate, a metal vaporized film or the like as a base material, it is preferable to contain a silane coupling agent from the viewpoint of improving the adhesive strength. ..

The silane coupling agent is not limited to the following, and is, for example, vinylsilanes such as vinyltris (β-methoxyethoxy) silane, vinylethoxysilane, and vinyltrimethoxysilane;
(Meta) acryloxysilanes such as γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxipropyltriethoxysilane, and γ- (meth) acryloxipropyldimethoxymethylsilane;
β- (3,4-epylcyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) methyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, β- (3,4-epoxycyclohexyl) 4-Epoxycyclohexyl) Epoxysilanes such as methyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxypropyltriethoxysilane;
N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldiethoxycisilane, γ-amino Aminosilanes such as propyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, and N-phenyl-γ-aminopropyltriethoxysilane;
In addition, thiosilanes such as γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane can be mentioned. These can be used alone or in any combination of two or more. In addition, "(meth) acryloxy" means "acryloxy" or "methacryloxy".

The amount of the silane coupling agent added is preferably 0.1 to 5 parts by mass, more preferably 1 to 3 parts by mass with respect to 100 parts by mass of the polyester-based polyol (A). When the content is 0.1 part by mass or more, the adhesive strength to the metal foil is improved.

Further, in order to improve metal adhesion, phosphoric acid-based compounds such as phosphoric acid, metaphosphoric acid, pyrophosphoric acid, phosphoric acid, and esters thereof can be added.

In addition, a reaction accelerator can be used for the adhesive. Specifically, metal-based catalysts such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin dimarate; 1,8-diaza-bicyclo (5,4,0) undecene-7,1,5-diazabicyclo ( 4,3,0) Nonene-5,6-dibutylamino-1,8-diazabicyclo (5,4,0) Undecene-7 and other tertiary amines;
Reactive tertiary amines such as triethanolamine can be mentioned, and one or more reaction promoters selected from these groups can be used.

A known leveling agent or defoaming agent may be added to the main agent for the purpose of improving the appearance of the laminate.

Examples of the leveling agent include polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyester-modified hydroxyl group-containing polydimethylsiloxane, polyether ester-modified hydroxyl group-containing polydimethylsiloxane, and acrylic copolymer. , Methacrylic copolymers, polyether-modified polymethylalkylsiloxanes, acrylic acid alkyl ester copolymers, methacrylic acid alkyl ester copolymers, lecithin, or mixtures thereof, and the like.

Examples of the defoaming agent include known ones such as a silicone resin, a silicone solution, a copolymer of an alkyl vinyl ether, an acrylic acid alkyl ester and a methacrylic acid alkyl ester, or a mixture thereof.

Further, as a known additive used in the present invention, a known phosphorus-based or phenol-based antioxidant is used for the purpose of suppressing deterioration of the adhesive composition for forming a laminated sheet due to ultraviolet rays such as the sun or heat over time. Agents, UV stabilizers, and metal inactivating agents can be added to the adhesive composition for forming a laminated sheet. These may be used alone or in any combination of two or more.
The amount of the phosphorus-based or phenol-based antioxidant, ultraviolet stabilizer, and metal inactivating agent used in the present invention is the polyester-based polyol (A) from the viewpoint of the balance between the yellowing suppressing effect and the adhesive strength. The range is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 1 part by mass with respect to 100 parts by mass.

Further, the adhesive composition for forming a laminated sheet of the present invention contains a known organic solvent and can be used as an organic solvent solution. The organic solvent is not limited to the following, and examples thereof include an ester solvent such as ethyl acetate or butyl acetate, or a ketone solvent such as methyl ethyl ketone, methyl isobutyl ketone, or cyclohexanone, and these may be used alone or. Two or more kinds can be mixed and used.

<< Laminated sheet >>
The laminated sheet of the present invention is made by using the above-mentioned adhesive composition for forming a laminated sheet according to the present invention, and can be specifically formed as follows.
That is, the adhesive composition for forming a laminated sheet according to the present invention is applied to a sheet-like substrate with a comma coater or the like, and after the solvent is volatilized as necessary, an almost uncured adhesive layer (precursor) is formed. Another sheet-like substrate is superposed on the precursor of the adhesive layer, and the adhesive is aged at room temperature or under heating to promote the curing of the adhesive to form a laminated sheet. The amount of the adhesive applied is preferably about 1 to 50 g / m ² in terms of dryness. As the sheet-like base material, any number of base materials can be selected according to the intended use, and in the case of a multi-layer structure of three or more layers, all or part of the bonding of each layer is performed. The adhesive composition according to the present invention can be used.

Examples of the sheet-like substrate include PET (polyethylene terephthalate) film, PEN (polyethylene naphthalate) film, fluorine-based film, and polyolefin film such as polypropylene.

Hereinafter, the present invention will be described in more detail with reference to Examples. In the examples, the part is the mass part at the time of solid conversion, and% is the mass%.

<Number average molecular weight, molecular weight distribution>
The number average molecular weight and molecular weight distribution of the polyester-based polyol (A) and the like were determined by GPC-RI.
Model: TOSOH HLC-8200GPC Column: TSKGEL SuperHM-M,
Solvent: THF solution, outflow rate: 0.6 ml / min, temperature: 40 ° C,
Detector: Differential refractometer Molecular weight standard: Polystyrene conversion

<Branch degree α>
The degree of branching α of the polyester-based polyol (A) or the like was determined by GPC-MALS-VISCO.
Model: Alliance GPC (manufactured by Waters), Column: TSKgel GMH HR-H (manufactured by Tosoh)
Solvent: THF solution, outflow rate: 1.0 ml / min, temperature: 40 ° C,
Detector: mini DAWN TREOS, ViscoStar-II, Optilab T-rEX (all manufactured by Waitt Technology)

<Glass transition temperature>
The glass transition temperature (Tg) was measured by DSC (Differential Scanning Calorimetry).
Specifically, about 2 mg of the polyester-based polyol (A) or the like is weighed on an aluminum pan, the aluminum pan is set in the DSC measurement holder, and the endothermic peak of the chart obtained under the heating condition of 5 ° C./min. Was read. The peak temperature at this time was defined as the glass transition temperature.

<Acid value (AV)>
About 1 g of the sample was precisely weighed into a stoppered Erlenmeyer flask, and 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution was added and dissolved. Phenolphthalein test solution was added as an indicator, held for 30 seconds, and then titrated with 0.1N alcoholic potassium hydroxide solution until the solution turned pink.
The acid value (mgKOH / g) was calculated as the value of the dried resin by the following formula.
Acid value (mgKOH / g) = {(5.611 × a × F) / S} / (nonvolatile content concentration / 100)
However, S: sample collection amount (g)
a: Consumption of 0.1N alcoholic potassium hydroxide solution (ml)
F: Titer of 0.1N alcoholic potassium hydroxide solution

(Manufacturing Example 1 for Examples)
As carboxylic acid components, phthalic anhydride 90 g (0.61 mol), isophthalic acid 266 g (1.60 mol), terephthalic acid 53 g (0.32 mol), sebacic acid 130 g (0.64 mol), benzoic acid 3.9 g (0. 032mol),
As a hydroxyl group component, 63 g (1.02 mol) of ethylene glycol, 146 g (1.41 mol) of neopentyl glycol, 125 g (1.06 mol) of 1,6-hexanediol, and 4.3 g (0.032 mol) of trimethylolpropane are reacted. Place in a container and gradually heat to 160-240 ° C while stirring under a nitrogen stream, carry out an esterification reaction at 240 ° C until the acid value becomes 15 or less, and then gradually reduce the pressure to 1 to 2 tolls to excess. Distillate off the hydroxyl group component of the above to obtain a polyester-based polyol A-1.
Assuming that the excess hydroxyl group component is distilled off almost evenly and the total of the carboxylic acid component and the hydroxyl group component is 200 mol%, the composition of the obtained polyester-based polyol A-1 is as shown in Table 1. Phthalan anhydride: Isophthalic acid: Terephthalic acid: Sebacic acid: Benzoic acid: Ethylene glycol: Neopentyl glycol: 1,6-hexanediol: Trimethylolpropane = 19:50:10:20: 1:29: 40: 30: It becomes 1 (mol%).
The obtained polyester-based polyol A-1 has a branching degree α of 0.593, a hydroxyl value of 18.3 (mg / KOH), an acid value of 0.2 (mg / KOH), and a number average molecular weight of 9,800. The mass average molecular weight was 19000, and the glass transition temperature (Tg) was 1 ° C.

(Manufacturing Examples 2-9, 11-13 for Examples)
The carboxylic acid component and the hydroxyl group component are reacted in the same manner as in Production Example 1 so that the obtained polyester-based polyol has a composition as shown in Table 1, and the polyester-based polyols A-2 to A-9 and A-11 are reacted. ~ A14 was obtained.

(Manufacturing Example 10 for Examples)
Similar to Synthesis Example 1, as carboxylic acid components, 350 g (2.11 mol) of isophthalic acid, 40 g (0.24 mol) of terephthalic acid, 122 g (0.60 mol) of sebacic acid, 7.3 g (0.060 mol) of benzoin,
As a hydroxyl group component, 56 g (0.90 mol) of ethylene glycol, 144 g (1.39 mol) of neopentyl glycol, 139 g (1.18 mol) of 1,6-hexanediol, and 8.1 g (0.060 mol) of trimethylolpropane are reacted. Let me
As shown in Table 1, isophthalic acid: terephthalic acid: sebacic acid: benzoic acid: ethylene glycol: neopentyl glycol: 1,6-hexanediol: trimethylolpropane = 70: 8: 20: 2: 23: 40: 34. : After obtaining a polyester having a composition of 2 (mol) having a hydroxyl value of about 25 gKOH / g and a number average molecular weight of about 8000, 1 g of isophthalone diisocyanate was added to 100 parts of the polyester, and a part of the hydroxyl groups in the polyester was reacted. The polyester polyurethane polyol A-10 was obtained.
The obtained polyester-based polyol A-10 has a branching degree α of 0.521, a hydroxyl value of 23.0 (mg / KOH), an acid value of 0.2 (mg / KOH), and a number average molecular weight of 9,000. The mass average molecular weight was 34,500, and the glass transition temperature (Tg) was 10 ° C.

(Manufacturing Examples 101 to 104 for Comparative Examples)
The carboxylic acid component and the hydroxyl group component were reacted in the same manner as in Synthesis Example 1 so that the obtained polyester-based polyol had a composition as shown in Table 1 to obtain polyester-based polyols A-101 to 103.
In Production Example 104 for Comparative Example, the polyester-based polyol could not be produced because it gelled due to the increase in molecular weight.

(Manufacturing Example 105 for Comparative Example)
Similar to Synthesis Example 1, isophthalic acid 61.4 g (0.41 mol), terephthalic acid 61.4 g (0.41 mol), sebacic acid 50.5 g (0.25 mol), benzoic acid 1.2 g (0.01 mol). ), And as shown in Table 1, isophthalic acid: terephthalic acid: sebacic acid: benzoic acid: ethylene glycol: neopentyl glycol: 1,6-hexanediol = 37: 37: 25: 1:30: 40: A polyester having a composition of 30: 1 (mol) having a hydroxyl value of about 9 mgKOH / g and a number average molecular weight of about 11000 was obtained.
Next, 300 g of the polyester was heated while stirring under a nitrogen stream, 3 g of isophorone diisocyanate was added in an atmosphere of 150 ° C., and stirring was continued. Stirring was continued until the absorption derived from the unreacted NCO group disappeared by IR analysis to obtain a urethane-modified polyester alcohol (U-1) having a hydroxyl value of about 7.5 mgKOH / g and a number average molecular weight of about 12200.
Further, 300 g of the urethane-modified polyester alcohol (U-1) is charged into a four-mouthed flask, heated to 180 ° C. with stirring in a nitrogen stream, and charged with 4 g of ethylene glycol bisanhydrotritate and 2 g of anhydrous trimellitic acid. , At 180 ° C. for 1 hour, 36% of the hydroxyl groups (calculated from the blending ratio) in the urethane-modified polyester polyol were modified with an acid, the hydroxyl value was about 5.1, and the acid value was about 4.7 mgKOH. A partially acid-modified polyester-based polyol (Comparative A-5) having / g and a number average molecular weight of about 17340 and an average number of hydroxyl groups per molecule of 1.13 was obtained.

The abbreviations in Tables 1 and 2 are as follows.
<Carboxylic acid component>
-Bifunctional PA: phthalic acid anhydride IPA: isophthalic acid TPA: terephthalic acid SeA: sebacic acid AdA: adipic acid Dimeric acid: C18 unsaturated fatty acid dimer (acid value 194)
Monofunctional PhA: benzoic acid unsaturated fatty acid: C18 unsaturated fatty acid (acid value 188)
Trifunctional TMA: Trimellitic anhydride Trimellitic acid: C18 unsaturated fatty acid trimer (acid value 194)

<Hydroxy group component>
・ Bifunctional EG: Ethylene glycol NPG: Neopentyl glycol 1,6-HD: 1,6-Hexanediol ・ Monofunctional LA: Lauryl alcohol ・ Trifunctional TMP: Trimethylolpropane

<Polyisocyanate component>
IPDI: Isophorone diisocyanate

<Ingredients for acid denaturation>
TMEG-S: Ethylene glycol bisanhydrotritate TMA: Anhydrous trimellitic acid

[Example 1]
The polyester-based polyol A-1 obtained in Production Example 1 for Examples was dissolved in ethyl acetate to prepare a solution having a solid content of 60%.
Polyisocyanate compound (B), epoxy resin, and silane coupling with respect to 166.6 parts of the solution (including 100 parts of polyester-based polyol A-1) according to the formulation shown in Table 3 (values in the table are parts by mass). After blending the agent, the solid content was diluted to 30% with ethyl acetate to obtain an adhesive solution.
According to the method described later, the pot life, shortening of aging time, and peel strength (before and after the moisture resistance test) were evaluated. The results are shown in Table 3.

[Examples 2 to 21], [Comparative Examples 1 to 6]
According to the formulation in Table 3 (values in the table are parts by mass), an adhesive solution was obtained in the same manner as in Example 1 and evaluated in the same manner.

The abbreviations in Table 3 are as follows.
<Epoxy resin>
Epoxy-1: Bisphenol A type epoxy resin (JER834, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 250, molecular weight approx. 470)
Epoxy-2: Bisphenol A type epoxy resin (JER1002, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 650, molecular weight approx. 1200)

<Polyisocyanate compound (B)>
Isocyanate-1: Isocyanurate structure of hexamethylene diisocyanate (NCO content 21.8% manufactured by Sumidure N-3300 Sumika Cobestlor Urethane)
Isosia-2: Trimethylolpropane adduct of hexamethylene diisocyanate (Takenate D-160N, manufactured by Mitsui Chemicals, Inc., NCO content 12.6%, non-volatile content 75%)

<Silane coupling agent>
SC-1: Glycydopropyltrimethoxysilane SC-2: Glycidopropyltriethoxysilane

<Evaluation of pot life>
For each adhesive, the viscosity at 25 ° C. after mixing the polyisocyanate compound (B) was measured after 1 hour, 4 hours, 8 hours, and 24 hours using a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd.). , 20 rpm, 2 minutes rotation, and the pot life was evaluated on a 4-point scale.
⊚: Viscosity increase rate after 24 hours is less than double. Very good.
◯: The rate of increase in viscosity after 8 hours is less than double. It is good.
Δ: The rate of increase in viscosity up to 4 hours is more than doubled. There is no problem in practical use.
X: The rate of increase in viscosity up to 1 hour is more than doubled. There is a problem in practical use.
In Example 1, the viscosity increase rate after 8 hours was 1.3 times, and the viscosity increase rate after 24 hours was 1.8 times, which were good.

<Evaluation of shortening of aging time>
Each adhesive solution is applied to a corona-treated polyester film [manufactured by Toray Industries, Inc., Lumirer X-10S, thickness 250 μm] with a dry laminator in an amount such that the dry coating amount is 4 to 5 g / m ² , and the solvent is volatilized. Then, it was laminated on an ETFE (ethylene-tetrafluoroethylene copolymer) -based film (manufactured by Asahi Glass Co., Ltd .: Fluon ETFE Film, thickness 25 μm)] to obtain a pre-laminated product.
The pre-laminates were then aged at 50 ° C. for 24 and 48 hours and at 25 ° C. for 72 and 168 hours.
The ETFE of the pre-laminate was peeled off, IR measurement was performed using Spectrum One manufactured by PerkinElmer, and the absorption spectrum of the reactive functional group (isocyanate group: 2270 to 2250 cm-1) of the adhesive layer and the ester bond C = O. The reaction rate of isocyanate groups before and after aging was evaluated from the peak height ratio of the absorption spectrum of stretching vibration (1750 to 1725 cm-1). The specific formula was obtained as follows.
Reaction rate (%) = 100-[((Peak height of isocyanate group after aging / Peak height of C = O after aging)) / ((Peak height of isocyanate group before aging / C before aging) = Peak height of O)))] × 100

The curing reactivity at 50 ° C. was evaluated in the following four stages.
⊚: No absorption of isocyanate groups was observed after 24 hours. The curing reactivity is very good.
◯: The reaction rate after 24 hours was 90% or more, and no absorption of isocyanate groups was observed after 48 hours. The curing reactivity is good.
Δ: The reaction rate after 24 hours was 70% or more and 90% or less, and the reaction rate after 48 hours was 90% or more, but absorption of isocyanate groups was observed and the curing reactivity was slightly insufficient. There is no problem in practical use.
X: The reaction rate after 48 hours is less than 70%, and the curing reactivity is insufficient. There is a problem in practical use.
In Example 1, the reaction rate after 24 hours was 99%, and the absorption spectrum of the isocyanate group was not observed after 48 hours, so that the curing reactivity was good.

The curing reactivity at 25 ° C. was evaluated in the following four stages.
⊚: No absorption of isocyanate groups was observed after 72 hours. The curing reactivity is very good.
◯: The reaction rate after 72 hours was 90% or more, and no absorption of isocyanate groups was observed after 168 hours. The curing reactivity is good.
Δ: The reaction rate after 72 hours was 70% or more and 90% or less, and the reaction rate after 168 hours was 90% or more, but absorption of isocyanate groups was observed and the curing reactivity was slightly insufficient. There is a problem in practical use.
X: The reaction rate after 168 hours is less than 70%, and the curing reactivity is insufficient. There is a problem in practical use.
In Example 1, the reaction rate after 72 hours was 99%, and the absorption spectrum of the isocyanate group was not observed after 168 hours, so that there was no problem with the curing reactivity.

<Evaluation of peel strength (before and after moisture resistance test)>
The following two types of laminates were prepared, and the peel strength (before and after the moist heat resistance test) was evaluated according to the method described later.
(1) Laminated body 1
Each adhesive solution is applied to a corona-treated polyester film [manufactured by Toray Industries, Inc., Lumirer X-10S, thickness 250 μm] with a dry laminator in an amount such that the dry coating amount is 4 to 5 g / m ² , and the solvent is volatilized. After that, it was laminated on an ETFE (ethylene-tetrafluoroethylene copolymer) -based film (manufactured by Asahi Glass Co., Ltd .: Fluon ETFE Film, thickness 25 μm)] to obtain each pre-laminated product, and each pre-laminated product was used at 50 ° C. for 48 hours. Aging was performed to prepare a laminated body 1.
(2) Production of Laminated Body 2 The laminated body is the same as that of the laminated body 1 except that the treated surfaces of the corona-treated CPP [(unstretched polypropylene) film 70 μm] are laminated with each adhesive solution. 2 was produced.

[Before moisture resistance test]
A test piece having a width of 15 mm was cut out from each of the laminates 1 and 2, and after standing for 6 hours in an environment of 25 ° C. and a humidity of 65%, a tensile tester was used according to the test method of ASTM-D1876-61. A 180 ° peeling test was performed on a test piece having a load speed of 100 mm / min and a width of 15 mm, and evaluation was performed in four stages.
⊚: Peeling strength is 8N or more. Very good adhesion.
◯: Peeling strength 5N or more and less than 8N. Excellent adhesiveness.
Δ: Peeling strength 3N or more and less than 5N. Adhesiveness is slightly insufficient and there is a problem in practical use. ×: Peeling strength is less than 3N. Poor adhesiveness There is a practical problem.

[After moisture resistance test]
Each laminate is set in a high pressure cooker (accelerated evaluation device using pressurized steam) in an environment of 120 ° C and 100% humidity.
For the laminate 1, after 48 hours and 96 hours of accelerated test,
For the laminated body 2, after the acceleration test for 192 hours,
After standing for 6 hours in an environment with a temperature of 25 ° C and a humidity of 65%, a 15 mm wide test piece was cut out.
A 180 ° peeling test was conducted under the same conditions as before the test, and evaluation was performed in the following four stages.
⊚: Peeling strength is 6N or more. Very good adhesion.
◯: Peeling strength 4N or more and less than 6N. Excellent adhesiveness.
Δ: Peeling strength 2N or more and less than 4N. Adhesiveness is a little insufficient, and there is a problem in practical use.
X: Peeling strength is less than 2N. Poor adhesiveness There is a practical problem.

As shown in Table 3, the adhesive composition for forming a laminated sheet of Examples achieves both stable pot life and shortening of aging time, has excellent peel strength before and after the moisture resistance test, and has a long term. It was found that the adhesive strength could be maintained over the years. It is considered that this is an effect of simultaneously improving the high cohesive force of the adhesive composition for forming a laminated sheet and the affinity with the base material at the time of coating by controlling the branching degree α of the polyester-based polyol (A). Be done. Furthermore, since the hydroxyl group involved in cross-linking with the polyisocyanate compound (B) can be easily controlled, the curing reactivity can be easily controlled, the effect of improving the hydrolysis resistance due to the high cross-linking density can be obtained, and the durability of the coating film can be obtained. This is probably because the sex has improved significantly.

Claims (5)

An adhesive composition for forming a laminated sheet, which comprises a polyester-based polyol (A) which is a reaction product of a carboxylic acid component and a hydroxyl group component and a polyisocyanate compound (B).
At least one of the carboxylic acid component and the hydroxyl group component contains a monofunctional component, and at least one of the carboxylic acid component and the hydroxyl group component contains a trifunctional or higher functional component.
The hydroxyl value of the polyester-based polyol (A) is 15 to 40 mg / KOH, the acid value is at most 0.5 mg / KOH, and the degree of branching α measured by GPC-MALS-VISCO is 0.6 or less. And
An adhesive composition for forming a laminated sheet , wherein the polyisocyanate compound (B) is an aliphatic polyisocyanate compound (B-1) . In a total of 200 mol% of the carboxylic acid component and the hydroxyl group component,
The adhesive composition for forming a laminated sheet according to claim 1, wherein the monofunctional component is 0.2 to 8 mol%, and the trifunctional or higher component is 0.2 to 8 mol%. The claim is characterized in that the number average molecular weight (Mn) of the polyester-based polyol (A) measured by GPC-RI is 2000 to 20000, and the molecular weight distribution (Mw / Mn) is 2.5 to 10. The adhesive composition for forming a laminated sheet according to 1 or 2. The adhesive composition for forming a laminated sheet according to any one of claims 1 to 3, wherein the polyester-based polyol (A) has a glass transition temperature of −35 to 15 ° C. A laminated sheet using the adhesive composition for forming a laminated sheet according to any one of claims 1 to 4 .