Adhesive composition, adhesive, and adhesive sheet

Abstract

To provide an adhesive composition that is solvent-free while being low in viscosity, thus ensuring favorable coating properties and kneading properties and superior adhesiveness, and an adhesive sheet using the adhesive composition.SOLUTION: The present invention provides an adhesive composition (X) containing a precursor of a block (A) of a polymer of a (meth)acrylate compound and a precursor of a block (B) of a urethane compound, an adhesive composition (X) containing an acrylic-urethane composite resin (C) in which a precursor of a block (A) of a copolymer of a (meth)acrylate compound and a precursor of a block (B) of a urethane compound are linked by a chain transfer agent residue obtained by removing a hydrogen atom from a hydroxyl group of a chain transfer agent, and an adhesive sheet.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet. [Background technology]

[0002] Pressure-sensitive adhesive sheets are made by laminating a pressure-sensitive adhesive onto a substrate (such as polyester, polyethylene, polypropylene, or glass), and are used in a wide range of fields, including optical components, automotive components, building materials, and medical applications.

[0003] These pressure-sensitive adhesive sheets mainly use acrylic pressure-sensitive adhesives containing polymers of (meth)acrylic compounds. Among acrylic pressure-sensitive adhesives, solvent-free acrylic pressure-sensitive adhesives have been proposed from the viewpoint of eliminating the need for a drying step for volatilizing the solvent after coating and efficiently forming a pressure-sensitive adhesive layer (for example, Patent Document 1). However, solvent-free acrylic adhesives have high viscosity, which makes them difficult to knead and difficult to handle, and also causes problems such as crosslinking between the hydroxyl and carboxyl groups that make up the acrylic adhesive when heated, resulting in poor coatability and failure to achieve the desired adhesiveness. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-76097 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a pressure-sensitive adhesive composition which is solvent-free and has low viscosity, and therefore has good coatability and kneadability, and excellent adhesiveness, and a pressure-sensitive adhesive sheet using the pressure-sensitive adhesive composition. [Means for solving the problem]

[0006] The present inventors conducted extensive research to solve the above-mentioned problems and arrived at the present invention. Specifically, the present invention provides a pressure-sensitive adhesive composition (X) containing a precursor of a (meth)acrylate compound polymer block (A) and a precursor of a urethane compound block (B), wherein the precursor of the (meth)acrylate compound polymer block (A) has a chain transfer agent residue having a hydroxyl group; a pressure-sensitive adhesive containing an acrylic-urethane hybrid resin (C) in which the (meth)acrylate compound polymer block (A) and the urethane compound block (B) are linked by a chain transfer agent residue formed by removing a hydrogen atom from the hydroxyl group of the chain transfer agent; and a pressure-sensitive adhesive sheet using the pressure-sensitive adhesive. [Effects of the Invention]

[0007] The pressure-sensitive adhesive composition (X) of the present invention has good coating properties and kneading properties, and when used as a pressure-sensitive adhesive, it exhibits excellent adhesive properties. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments of the present invention will be described in detail below. Unless otherwise specified, the expression "A to B" for numerical values ​​A and B means "A or more and B or less." In such expressions, when a unit is assigned only to numerical value B, the unit also applies to numerical value A. In the present invention, the term "(meth)acrylic" means acrylic and / or methacrylic, the term "(meth)acrylate" means acrylate and / or methacrylate, the term "(meth)acryloyl" means acryloyl and / or methacryloyl, and the term "(meth)acryloyloxy" means acryloyloxy and / or methacryloyloxy.

[0009] In the present invention, the pressure-sensitive adhesive composition (X) is a pressure-sensitive adhesive composition (X) containing a precursor of a block (A) of a polymer of a (meth)acrylate compound and a precursor of a block (B) of a urethane compound, and the precursor of the block (A) of the polymer of a (meth)acrylate compound has a chain transfer agent residue having a hydroxyl group.

[0010] <Precursor of Block (A) of Polymer of (Meth)acrylate Compound> The precursor of the block (A) of the polymer of the (meth)acrylate compound is a structure obtained by polymerizing a chain transfer agent having a hydroxyl group and a (meth)acrylate compound in the presence of a polymerization initiator.

[0011] <Chain transfer agent> The chain transfer agent is not particularly limited as long as it has a hydroxyl group and a functional group for chain transfer, but one having a sulfanyl group (-SH) as the functional group for chain transfer is preferred. When the chain transfer agent and a (meth)acrylate compound are polymerized in the presence of a polymerization initiator, a poly(meth)acrylate having a hydroxyl group derived from the chain transfer agent {a precursor of block (A) of the polymer of the (meth)acrylate compound} is obtained. The chain transfer agent can be selected from known chain transfer agents and used alone or in combination of two or more.

[0012] Preferred examples of compounds having a hydroxyl group and a sulfanyl group in the molecule include those having 2 to 6 carbon atoms, such as mercaptoethanol, mercaptobutanol, mercaptobutanediol, hydroxybenzenethiol, and 3-mercapto-1,2-propanediol. Among these, from the viewpoint of adhesive strength, compounds having two or more hydroxyl groups and sulfanyl groups in the molecule are preferred, and 3-mercapto-1,2-propanediol is more preferred.

[0013] The amount of the chain transfer agent used is preferably 0.1 to 4.0 parts by mass, and more preferably 1.0 to 2.0 parts by mass, based on 100 parts by mass of the monomer constituting the precursor of block (A) of the polymer of the (meth)acrylate compound, from the viewpoint of adhesive strength.

[0014] <(Meth)acrylate compounds> The (meth)acrylate compound may be a monofunctional (meth)acrylic monomer or a polyfunctional (meth)acrylic monomer, which may be used alone or in combination of two or more.

[0015] (Monofunctional (meth)acrylic monomer) Examples of the monofunctional (meth)acrylic monomer include (meth)acrylic acid, a monoester of (meth)acrylic acid with an alcohol having 1 to 20 carbon atoms, a monoester of (meth)acrylic acid with an alkylene oxide adduct of an alcohol having 1 to 20 carbon atoms, a reaction product of a (meth)acrylic acid ester having a hydroxyl group and an acid anhydride, an alkoxysilane having a (meth)acryloyl group, and a lactone adduct of (meth)acrylic acid. The monofunctional (meth)acrylic monomer may also be a compound in which the hydrogen atoms of the above compounds are substituted with halogen atoms, carboxy groups, cyano groups, amino groups, and / or alkylamino groups (dimethylamino groups, diethylamino groups, etc.).

[0016] Examples of the alcohol having 1 to 20 carbon atoms include chain aliphatic alcohols having 1 to 20 carbon atoms, alicyclic alcohols having 3 to 20 carbon atoms, and aromatic alcohols having 6 to 15 carbon atoms.

[0017] Examples of the chain aliphatic alcohol having 1 to 20 carbon atoms include chain aliphatic monohydric alcohols having 1 to 20 carbon atoms [methanol, ethanol, 1-propanol, 1-butanol, t-butyl alcohol, 1-pentanol, isoamyl alcohol, 1-hexanol, 2-ethylhexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, stearyl alcohol, and butoxymethanol]; chain aliphatic dihydric alcohols having 2 to 20 carbon atoms [ethylene glycol, 1,2- or 1,3-propylene glycol, 1,2-butanediol, 1,4-butanediol, 1,6 ... hexanediol, 1,8-octanediol, 1,10-decanediol, dodecanediol, tetradecanediol, neopentyl glycol, 2,2-diethyl-1,3-propanediol, etc.); chain aliphatic trihydric alcohols having 3 to 20 carbon atoms [glycerin, trimethylolethane, trimethylolpropane, 1,3,5-triazine-2,4,6-triol, etc.]; and chain aliphatic tetrahydric to octahydric alcohols having 5 to 20 carbon atoms [pentaerythritol, ditrimethylolpropane, sorbitol, mannitol, sorbitan, diglycerin, dipentaerythritol, etc.].

[0018] Examples of the alicyclic alcohol having 3 to 20 carbon atoms include hydroxycyclohexane, 4-n-butylcyclohexyl, bornyl alcohol, isobornyl alcohol, 1,3-cyclopentanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-cycloheptanediol, 2,2-bis(4-hydroxycyclohexyl)propane, 1,3,5-cyclohexanetriol, and glycidol.

[0019] Examples of the aromatic alcohol having 6 to 15 carbon atoms include phenol, 4-butylphenol, cresol, pyrogallol, catechol, resorcinol, hydroquinone, dihydroxynaphthalene, bisphenol A, bisphenol F, bisphenol S, phenoxymethanol, and benzyl alcohol.

[0020] Specific examples of the monoesters of chain aliphatic alcohols having 1 to 20 carbon atoms with (meth)acrylic acid include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, tert-octyl (meth)acrylate, 2,3-dimethylhexyl (meth)acrylate, isoamyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and butoxymethyl (meth)acrylate. Furthermore, examples of the monoesters of the chain aliphatic alcohols having 1 to 20 carbon atoms and (meth)acrylic acid in which the hydrogen atoms have been substituted with halogen atoms, carboxy groups, cyano groups, amino groups, and / or alkylamino groups (dimethylamino groups, diethylamino groups, etc.) include 2-chloroethyl (meth)acrylate, 4-bromobutyl (meth)acrylate, 2,2,2-tetrafluoroethyl (meth)acrylate, 1H,1H,2H,2H-perfluorodecyl (meth)acrylate, trifluoroethyl (meth)acrylate, perfluorooctylethyl (meth)acrylate, cyanoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, diethylaminopropyl (meth)acrylate, and β-carboxyethyl (meth)acrylate.

[0021] Specific examples of the monoesters of the alicyclic alcohols having 3 to 20 carbon atoms and (meth)acrylic acid include glycidyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-n-butylcyclohexyl (meth)acrylate, bornyl (meth)acrylate, and isobornyl (meth)acrylate.

[0022] Specific examples of the monoesters of aromatic alcohols having 6 to 15 carbon atoms with (meth)acrylic acid include benzyl (meth)acrylate, 4-butylphenyl (meth)acrylate, phenyl (meth)acrylate, 2,4,5-tetramethylphenyl (meth)acrylate, and phenoxymethyl (meth)acrylate. Furthermore, examples of the monoesters of the above-mentioned aromatic alcohols having 6 to 15 carbon atoms and (meth)acrylic acid in which hydrogen atoms have been substituted with halogen atoms, carboxy groups, cyano groups, amino groups, and / or alkylamino groups (dimethylamino groups, diethylamino groups, etc.) include 4-chlorophenyl (meth)acrylate.

[0023] The alkylene oxide used as a raw material for the monoesterification product of an alkylene oxide adduct of an alcohol having 1 to 20 carbon atoms and (meth)acrylic acid includes alkylene oxides having 2 to 4 carbon atoms, and specific examples thereof include ethylene oxide, 1,2- or 1,3-propylene oxide, and 1,2-, 1,3-, 1,4-, or 2,3-butylene oxide. The number of moles of alkylene oxide added to the alcohol having 1 to 20 carbon atoms is preferably 1 to 40 moles. Examples of the monoesters of alkylene oxide adducts of alcohols having 1 to 20 carbon atoms and (meth)acrylic acid include 2-ethylhexyl dipropylene glycol (meth)acrylate, butoxyethyl (meth)acrylate, methoxypropylene mono(meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-ethylhexyl carbitol (meth)acrylate, 2-(2-methoxyethoxy)ethyl (meth)acrylate, 2-(2-butoxyethoxy)ethyl (meth)acrylate, polyethylene oxide monomethyl ether (meth)acrylate, oligoethylene oxide monomethyl ether (meth)acrylate, polyethylene oxide monomethyl ether (meth)acrylate, oligoethylene oxide monomethyl ether (meth)acrylate, dipropylene glycol monomethyl ether (meth)acrylate, and polypropylene oxide monomethyl ether (meth)acrylate. Examples of the nonylphenol (meth)acrylate include ethylene oxide (hereinafter sometimes abbreviated as EO)-modified phenol (meth)acrylate, EO-modified cresol (meth)acrylate, EO-modified nonylphenol (meth)acrylate, propylene oxide (hereinafter sometimes abbreviated as PO)-modified nonylphenol (meth)acrylate, EO-modified 2-ethylhexyl (meth)acrylate, 2-(2-vinyloxyethoxy)ethyl (meth)acrylate, glycidyloxybutyl (meth)acrylate, glycidyloxypropyl (meth)acrylate, and glycidyloxyethyl (meth)acrylate.

[0024] Examples of the (meth)acrylic acid ester having a hydroxyl group that serves as a raw material for the reaction product of the (meth)acrylic acid ester having a hydroxyl group and an acid anhydride include compounds in which the alcohol having 1 to 20 carbon atoms is a dihydric or higher alcohol, out of the monoesters of the alcohol having 1 to 20 carbon atoms and (meth)acrylic acid and the monoesters of the alkylene oxide adducts of the alcohol having 1 to 20 carbon atoms and (meth)acrylic acid. The acid anhydride may be an acid anhydride having 4 to 10 carbon atoms, and specific examples thereof include succinic anhydride, maleic anhydride, phthalic anhydride, and hexahydrophthalic anhydride. Examples of the reaction product of the (meth)acrylic acid ester having a hydroxyl group with an acid anhydride include 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 4-hydroxybutyl (meth)acrylate succinic acid adduct, 1,4-cyclohexanedimethanol mono(meth)acrylate succinic acid adduct, 1,4-benzenedimethanol mono(meth)acrylate succinic acid adduct, 2-(meth)acryloyloxyethyl phthalic acid, and polyol (divalent to hexavalent, preferably divalent, having 2 to 10 carbon atoms, preferably having 2 to 6 carbon atoms) alkylene oxide (having 2 to 4 carbon atoms) adduct (having 1 to 30 carbon atoms) mono(meth)acrylate succinic acid ester.

[0025] Examples of the alkoxysilane having a (meth)acryloyl group include trimethoxysilylpropyl (meth)acrylate, trimethoxysilylpropyl (meth)acrylate, and trimethylsilylpropyl (meth)acrylate.

[0026] Examples of lactones that can be used as raw materials for the lactone adducts of (meth)acrylic acid include lactones having 2 to 12 carbon atoms, and specific examples thereof include acetolactone, propiolactone, butyrolactone, valerolactone, caprolactone, and laurolactone. The number of moles of lactone added to the alcohol having 1 to 20 carbon atoms is preferably 1 to 15 moles. Examples of the lactone adducts of (meth)acrylic acid include ω-carboxy-caprolactone mono(meth)acrylate and ω-carboxy-di-(caprolactone) mono(meth)acrylate.

[0027] Among the above-mentioned monofunctional (meth)acrylic monomers, from the viewpoint of adhesiveness, a monoester of an alcohol having 1 to 20 carbon atoms with (meth)acrylic acid is preferred, butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are more preferred, and butyl (meth)acrylate is particularly preferred. The monofunctional (meth)acrylic monomers may be used alone or in combination of two or more.

[0028] (Polyfunctional (meth)acrylic monomer) Examples of the polyfunctional (meth)acrylic monomer include difunctional (meth)acrylic monomers, trifunctional (meth)acrylic monomers, and tetrafunctional or higher functional (meth)acrylic monomers.

[0029] [Bifunctional (meth)acrylic monomer] Examples of the bifunctional (meth)acrylic monomer include an ester of 1 mol of a dihydric or higher alcohol selected from the above alcohols having 1 to 20 carbon atoms with 2 mol of (meth)acrylic acid; an ester of 1 mol of an alkylene oxide adduct of a dihydric or higher alcohol selected from the above alcohols having 1 to 20 carbon atoms with 2 mol of (meth)acrylic acid; and an ester of 1 mol of a lactone adduct of a dihydric or higher alcohol selected from the above alcohols having 1 to 20 carbon atoms with 2 mol of (meth)acrylic acid. The bifunctional (meth)acrylic monomer may also be a compound obtained by reacting the hydroxyl group of the above esterified product that has not reacted with (meth)acrylic acid with a carboxylic acid having 2 to 10 carbon atoms (such as propionic acid). Specific examples of the bifunctional (meth)acrylic monomer include 1,6-hexanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 2,4-dimethyl-1,5-pentanediol di(meth)acrylate, butylethylpropanediol di(meth)acrylate, ethoxylated cyclohexanemethanol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, oligoethylene glycol di(meth)acrylate, ethylene Examples of the di(meth)acrylate include glycol di(meth)acrylate, 2-ethyl-2-butyl-butanediol di(meth)acrylate, EO-modified bisphenol A di(meth)acrylate, EO-modified bisphenol F di(meth)acrylate, polypropylene glycol di(meth)acrylate, oligopropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 2-ethyl-2-butyl-propanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and PO-modified and EO-modified bisphenol A di(meth)acrylate.

[0030] [Trifunctional (meth)acrylic monomer] Examples of the trifunctional (meth)acrylic monomer include an ester of 1 mol of a trivalent or higher alcohol selected from the above-mentioned alcohols having 1 to 20 carbon atoms with 3 mol of (meth)acrylic acid; an ester of 1 mol of an alkylene oxide adduct of a trivalent or higher alcohol selected from the above-mentioned alcohols having 1 to 20 carbon atoms with 3 mol of (meth)acrylic acid; and an ester of 1 mol of a lactone adduct of a trivalent or higher alcohol selected from the above-mentioned alcohols having 1 to 20 carbon atoms with 3 mol of (meth)acrylic acid. The trifunctional (meth)acrylic monomer may also be a compound obtained by reacting the hydroxyl group of the above esterified product that has not reacted with (meth)acrylic acid with a carboxylic acid having 2 to 10 carbon atoms (such as propionic acid). Specific examples of trifunctional (meth)acrylic monomers include trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, alkylene oxide-modified tri(meth)acrylate of trimethylolpropane, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, trimethylolpropane tri[(meth)acryloyloxypropyl]ether, sorbitol tri(meth)acrylate, tri(meth)acrylate of an adduct of pentaerythritol with 1 to 30 moles of alkylene oxide having 2 to 3 carbon atoms, ethoxylated glycerin tri(meth)acrylate, dipentaerythritol propionate tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, and ethoxylated isocyanuric acid tri(meth)acrylate.

[0031] [Trifunctional or higher (meth)acrylic monomers] The tetrafunctional or higher (meth)acrylic monomer includes a tetrafunctional or higher (meth)acrylic monomer other than a tetrafunctional or higher urethane (meth)acrylic monomer.

[0032] Examples of the tetrafunctional or higher (meth)acrylic monomer include an ester of 1 mol of a tetrahydric or higher alcohol selected from the above-mentioned alcohols having 1 to 20 carbon atoms with 4 mols or more of (meth)acrylic acid; an ester of 1 mol of an alkylene oxide adduct to a tetrahydric or higher alcohol selected from the above-mentioned alcohols having 1 to 20 carbon atoms with 4 mols or more of (meth)acrylic acid; and an ester of 1 mol of a lactone adduct to a tetrahydric or higher alcohol selected from the above-mentioned alcohols having 1 to 20 carbon atoms with 4 mols or more of (meth)acrylic acid. The tetrafunctional or higher (meth)acrylic monomer may be a compound obtained by reacting the hydroxyl groups of the above esterified product that have not reacted with (meth)acrylic acid with a carboxylic acid having 2 to 10 carbon atoms (such as propionic acid). Specific examples of the tetrafunctional or higher (meth)acrylic monomer include pentaerythritol tetra(meth)acrylate, sorbitol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol propionate tetra(meth)acrylate, tetra(meth)acrylate of an adduct of pentaerythritol with 1 to 11 moles of alkylene oxide having 2 to 3 carbon atoms, sorbitol penta(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, sorbitol hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate.

[0033] Among the polyfunctional (meth)acrylic monomers, trifunctional (meth)acrylic monomers and tetrafunctional or higher functional (meth)acrylic monomers are preferred from the viewpoint of curability, and tetrafunctional or higher functional (meth)acrylic monomers are more preferred. The polyfunctional (meth)acrylic monomers may be used alone or in combination of two or more.

[0034] <Polymerization initiator> As the polymerization initiator, known azo compounds and organic peroxides can be used, and these may be used alone or in combination of two or more. The azo compound is not particularly limited, and examples thereof include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), dimethyl 1,1'-azobis(1-cyclohexanecarboxylate), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), and 2,2'-azobis[2-(2-imidazolin-2-yl)propane]. The organic peroxide is not particularly limited, and examples thereof include benzoyl peroxide, t-butyl peroxy 2-ethylhexaate, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl)peroxydicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxypivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionyl peroxide, and diacetyl peroxide.

[0035] As the polymerization initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) is preferred from the viewpoint of molecular weight control.

[0036] The amount of the polymerization initiator used is preferably 0.001 to 15 parts by mass, more preferably 0.001 to 0.1 part by mass, relative to 100 parts by mass of the monomer constituting the precursor of block (A) of the (meth)acrylate compound polymer. A range of 0.001 to 15 parts by mass is preferred because chain transfer polymerization proceeds effectively.

[0037] The weight average molecular weight (Mw) of the precursor of the block (A) of the polymer of the (meth)acrylate compound is preferably 4,000 to 15,000, more preferably 5,000 to 10,000, from the viewpoint of adhesive strength.

[0038] The molecular weight distribution {weight average molecular weight (Mw) / number average molecular weight (Mn)} of the precursor of the polymer block (A) of the (meth)acrylate compound is preferably 1.5 to 2.5, more preferably 1.7 to 2.2, from the viewpoint of adhesive strength.

[0039] In the present invention, Mw and Mn can be measured by gel permeation chromatography under the following conditions, for example. Equipment: "HLC-8120GPC" [Tosoh Corporation] Columns: "Guardcolumn HXL-H" (1 tube) and "TSKgel GMHXL" (2 tubes) [both manufactured by Tosoh Corporation] Sample solution: 0.25% by weight tetrahydrofuran solution Solution injection volume: 100μl Flow rate: 1ml / min Measurement temperature: 40℃ Detector: Refractive index detector Reference material: Standard polystyrene

[0040] The glass transition temperature (Tg) of the precursor of the block (A) of the polymer of the (meth)acrylate compound is preferably from -50 to 0°C, more preferably from -40 to -10°C, from the viewpoint of adhesiveness. The glass transition temperature (Tg) is the temperature at which the loss factor (tan δ) of the polymer (A) peaks when measured under the following conditions using a viscoelasticity measuring device (e.g., model MCR-302, manufactured by Anton Paar). - Jig: φ8mm parallel plate. -Sample thickness: 1mm. -Distortion: 1% -Frequency: 1Hz -Heating rate: 10℃ / min. -Temperature range: -100℃ to 180℃.

[0041] The viscosity at 25° C. of the precursor of the block (A) of the polymer of the (meth)acrylate compound is preferably 5000 to 20000 mPa·s, more preferably 5000 to 15000 mPa·s, from the viewpoint of kneadability. The viscosity at 25° C. of the precursor of the block (A) of the polymer of the (meth)acrylate compound can be measured using a B-type viscometer in accordance with JIS-K7117-1.

[0042] The hydroxyl value of the precursor of the block (A) of the polymer of the (meth)acrylate compound is preferably from 10 to 50 mgKOH / g, more preferably from 15 to 45 mgKOH / g, from the viewpoint of adhesiveness. The hydroxyl value is a value measured in accordance with JIS K0070.

[0043] <Precursor of urethane compound block (B)> The precursor of the block (B) of the urethane compound can be formed by reacting a polyol with a polyisocyanate. From the viewpoint of adhesiveness, the precursor of the block (B) of the urethane compound preferably has an isocyanate group.

[0044] <Polyol> Examples of polyols constituting the block (B) of the urethane compound include polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, vegetable oil-based polyols, and other polyols, which may be used singly or in combination of two or more.

[0045] (Polyether polyol) Examples of polyether polyols include polymers of methylene oxide, ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, and the like; and glycols such as polyethylene glycol, polypropylene glycol, poly(ethylene / propylene) glycol, and polytetramethylene glycol as polymers; condensates of hexanediol, methylhexanediol, heptanediol, octanediol, or mixtures thereof; and polyols obtained by adding alkylene oxides such as methylene oxide, ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, or polyoxytetramethylene oxide to a compound having two or more active hydrogen groups.

[0046] Examples of the compound having two or more active hydrogen groups include low molecular weight polyols, aliphatic amine compounds, aromatic amine compounds, alkanolamines, and bisphenols.

[0047] The low molecular weight polyols include those having a molecular weight of 500 or less, such as difunctional low molecular weight polyols and trifunctional or higher functional low molecular weight polyols.

[0048] The bifunctional low molecular weight polyol is not particularly limited, and examples thereof include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, hexanediol, octanediol, nonanediol, dipropylene glycol, diethylene glycol, triethylene glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,5-pentane ... Examples of suitable hydroxybenzoates include methyl-1,8-octanediol, polyoxyethylene glycol, polyoxypropylene glycol, cyclohexanediol, cyclohexanedimethanol, tricyclodecane dimethanol, cyclopentadiene dimethanol, dimer diol, bisphenol A, N,N-bis(2-hydroxypropyl)aniline, dimethylolacetic acid, dimethylolpropionic acid, dimethylolbutanoic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid, dihydroxysuccinic acid, dihydroxypropionic acid, and dihydroxybenzoic acid.

[0049] The tri- or higher functional low molecular weight polyol is not particularly limited, and examples thereof include trimethylolethane, trimethylolpropane, 1,1,1-trimethylolbutane, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,6-butanetriol, trimethylolbutene, trimethylolpentene, trimethylolhexene, trimethylolheptene, trimethyloloctene, trimethylolnonene, trimethyloldecene, trimethylolundecene, trimethyloldodecene, trimethyloltridecene, trimethylolpentadecene, Trimethylolhexadecene, trimetrolheptadecene, trimethyloloctadecene, 1,1,1-trimethylol-2-methyl-hexane, 1,1,1-trimethylol-3-methyl-hexane, 1,1,1-trimethylol-2-ethyl-hexane, 1,1,1-trimethylol-3-ethyl-hexane, trimethylolhexene, 1,2,3-octanetriol, 1,3,7-octanetriol, 3,7-dimethyl-1,2,3-octanetriol, 1,1,1-, 1,1,1-trimethyloldecane, 1,2,10-decanetriol 1,1,1-trimethylolisoheptadecane, 1,1,1-trimethylol-sec-butane, 1,1,1-trimethylol-tert-pentane, 1,1,1-trimethylol-tert-nonane, 1,1,1-trimethylol-tert-tridecane, 1,1,1-trimethylol-tert-heptadecane, 1,1,1-trimethylol-2-methyl-hexane, 1,1,1-trimethylol-3-methyl-hexane, 1,1,1-trimethylol-2-ethyl-hexane, 1,1,1-trimethylol-3-ethyl-hexane, 1,1,1 -trimethylol isoheptadecane, 1,2,3,4-butanetetraol, pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, diglycerin, triglycerin, ditrimethylolethane, ditrimethylolpropane, tris(2-hydroxyethyl)isocyanurate, benzene-1,3,5-triol, benzene-1,2,3-triol, stilbene-3,4',5-triol, sucrose, inositol, sorbitan, sorbitol, mannitol, sucrose, and xylitol.

[0050] Examples of aliphatic amine compounds include ethylenediamine, triethylenetetramine, diethylenetriamine, and triaminopropane. Examples of aromatic amine compounds include toluenediamine and diphenylmethane-4,4-diamine. Examples of alkanolamines include ethanolamine and diethanolamine.

[0051] (polyester polyol) Examples of polyester polyols include polyester polyols obtained by condensation reaction of the above-mentioned low molecular weight polyols with dibasic acid components. Examples of the dibasic acid component include aliphatic or aromatic dibasic acids such as terephthalic acid, adipic acid, azelaic acid, sebacic acid, dimer acid, hydrogenated dimer acid, phthalic anhydride, isophthalic acid, trimellitic acid, glutaric acid, pimelic acid, suberic acid, and sebacic acid, and anhydrides thereof.

[0052] Furthermore, as the polyester polyol, polyester polyols obtained by ring-opening polymerization of cyclic ester compounds of lactones such as ε-caprolactone, poly(β-methyl-γ-valerolactone), polyvalerolactone, etc. may be used.

[0053] (Polycarbonate polyol) Examples of polycarbonate polyols include those obtained by reacting the above-mentioned low molecular weight polyols with carbonate compounds such as dialkyl carbonates, alkylene carbonates, diaryl carbonates, and the like. As the dialkyl carbonate, dimethyl carbonate or diethyl carbonate can be used, as the alkylene carbonate, ethylene carbonate can be used, and as the diaryl carbonate, diphenyl carbonate can be used.

[0054] (Polyolefin polyol) Examples of polyolefin polyols include hydroxyl group-containing polybutadiene, hydrogenated hydroxyl group-containing polybutadiene, hydroxyl group-containing polyisoprene, hydrogenated hydroxyl group-containing polyisoprene, hydroxyl group-containing chlorinated polypropylene, and hydroxyl group-containing chlorinated polyethylene.

[0055] (Vegetable oil-based polyol) Examples of vegetable oil-based polyols include polyols made from plant-derived castor oil, dimer acid, or soybean oil.

[0056] The polyol is preferably a polyether polyol, a polyester polyol, a polyolefin polyol or a polycarbonate polyol, and more preferably a polyether polyol.

[0057] The number average molecular weight of the polyol is preferably 150 to 5,000, and more preferably 200 to 3,500.

[0058] The polyol may contain other polyols than those mentioned above, and the above-mentioned low molecular weight polyols can be used in combination for the purpose of adjusting the urethane bond concentration and introducing various functional groups.

[0059] <Polyisocyanate> Examples of polyisocyanates constituting the precursor of the urethane compound block (B) include aromatic, aliphatic, and alicyclic diisocyanates, which may be used alone or in combination of two or more.

[0060] Examples of aromatic diisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, xylylene diisocyanate, m-tetramethylxylene diisocyanate, p-tetramethylxylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, and 1,5-tetrahydronaphthalene diisocyanate.

[0061] Examples of aliphatic diisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, lysine ester triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate tetramethylene diisocyanate, pentamethylene diisocyanate, and trimethylhexamethylene diisocyanate.

[0062] Examples of alicyclic diisocyanates include isophorone diisocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanatomethyl)cyclohexane, hydrogenated xylylene diisocyanate, dimer acid diisocyanate, and norbornene diisocyanate.

[0063] The polyisocyanate is preferably an aromatic diisocyanate, and more preferably 4,4'-diphenylmethane diisocyanate or 2,4-diphenylmethane diisocyanate.

[0064] The reaction between polyol and polyisocyanate can be carried out preferably in the absence of a solvent using a known urethane reaction, and by using an excess of polyisocyanate, a urethane compound having isocyanate groups at both ends can be obtained. From the viewpoint of reactivity, the molar ratio of isocyanate groups to hydroxyl groups during the reaction (NCO moles / OH moles) is preferably 1.05 to 6.00, more preferably 2.0 to 5.0. In the urethanization reaction, a catalyst may be used to adjust the reactivity.

[0065] (catalyst) Known metal catalysts, amine catalysts, etc. can be used as the catalyst. Examples of metal catalysts include dibutyltin dilaurate, tin octoate, dibutyltin di(2-ethylhexoate), lead 2-ethylhexoate, 2-ethylhexyl titanate, titanium ethyl acetate, iron 2-ethylhexoate, cobalt 2-ethylhexoate, bismuth 2-ethylhexoate, zinc naphthenate, cobalt naphthenate, and tetra-n-butyltin. Examples of amine catalysts include tertiary amines such as tetramethylbutanediamine. The amount of catalyst used is preferably in the range of 0.05 to 1.00 parts by mass relative to the polyol.

[0066] The isocyanate content of the precursor of the block (B) of the urethane compound is preferably 5 to 30% by mass, more preferably 7.5 to 25% by mass, from the viewpoint of adhesiveness.

[0067] The viscosity of the precursor of the urethane compound block (B) at 25° C. is preferably 500 to 10,000 mPa·s, more preferably 500 to 7,000 mPa·s, from the viewpoint of kneadability. The viscosity of the precursor of the urethane compound block (A) at 25° C. can be measured using a B-type viscometer in accordance with JIS-K7117-1.

[0068] <Adhesive composition (X)> The pressure-sensitive adhesive composition (X) of the present invention contains a precursor of the block (A) of the polymer of the (meth)acrylate compound and a precursor of the block (B) of the urethane compound.

[0069] The pressure-sensitive adhesive composition (X) of the present invention may contain, in addition to the precursor of the polymer block (A) of the (meth)acrylate compound and the precursor of the block (B) of the urethane compound, other components such as antioxidants, cure retarders, ultraviolet absorbers, plasticizers, tackifiers, fillers, and pigments, within limits that do not impair the effects of the present invention. The other components may be added to either the precursor of the block (A) of the polymer of the (meth)acrylate compound or the precursor of the block (B) of the urethane compound, or may be added when the precursor of the block (A) of the polymer of the (meth)acrylate compound and the precursor of the block (B) of the urethane compound are blended together. However, it is preferable to add the other components in advance to the precursor of the block (A) of the polymer of the (meth)acrylate compound.

[0070] Examples of antioxidants include hindered phenol compounds such as triethylene glycol bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], and 2,2-thiodiethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], and phosphite compounds such as tris(2,4-di-t-butylphenyl)phosphite, 2,2-methylenebis(4,6-di-t-butylphenyl)octylphosphite, bis(2,6-di-t-butylphenyl)pentaerythritol diphosphite, and tetrakis(2,4-di-t-butylphenyl)4,4'-biphenylene diphosphonite. These antioxidants may be used alone or in combination. The amount of antioxidant used is preferably 5 parts by mass or less, more preferably 0.05 to 1 part by mass, per 100 parts by mass of the adhesive composition (X) from the viewpoint of antioxidant effect and adhesive strength.

[0071] Examples of cure retarders include 2,4-pentanedione (acetylacetone), 3-methyl-2,4-pentanedione, 2,4-hexanedione, 2,2-dimethyl-3,5-hexanedione, 2,4-heptanedione, 3,5-heptanedione, 2,2,6,6-tetramethyl-3,5-heptanedione, 2,4-octanedione, 2,2,7-trimethyl-3,5-octanedione, 2,4-nonanedione, 3-methyl-2,4-nonanedione, 2-methyl-4,6-nonanedione, 1-phenyl-1,3-butanedione (benzoylacetone), β-diketones such as dibenzoylmethane and 2-furoylbenzoylmethane; methyl acetoacetate; and acetoacetic acid. Examples of curing retarders include β-ketoesters such as ethyl, propyl acetoacetate, butyl acetoacetate, methyl propionylacetate, ethyl propionylacetate, propyl propionylacetate, isopropyl propionylacetate, butyl propionylacetate, methyl butyrylacetate, ethyl butyrylacetate, propyl butyrylacetate, methyl caproylacetate, ethyl caproylacetate, propyl caproylacetate, and butyl caproylacetate; dialkyl malonates such as dimethyl malonate, diethyl malonate, methyl ethyl malonate, diisopropyl malonate, and dibutyl malonate; and acetoacetamides such as N,N-dimethylacetoacetamide and N-ethylacetoacetamide. These curing retarders may be used alone or in combination of two or more. The amount of the curing retarder used is preferably 5 parts by mass or less, more preferably 0.01 to 3 parts by mass, per 100 parts by mass of the adhesive composition (X), from the viewpoint of the curing retardation effect and adhesive strength.

[0072] UV absorbers include salicylic acid derivatives (phenyl salicylate, p-octylphenyl salicylate, p-tert-butylphenyl salicylate, etc.), benzophenone compounds (2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxy-5-sulfobenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, , 2-hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2-hydroxy-4-(2-hydroxy-3-methacryloxy)propoxybenzophenone and bis(2-methoxy-4-hydroxy-5-benzoylphenyl)methane, etc.], benzotriazole compounds {2-(2'-hydroxy-5 '-methyl-phenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butyl-phenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methyl-phenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-t-butyl-phenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-4'-n-octoxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-butylphenyl)benzotriazole, 2-(2'-hydroxy 2-[2'-hydroxy-3'-(3",4",5",6"-tetrahydrophthalimidomethyl)-5'-methylphenyl]benzotriazole, 2,2-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol], etc.; cyanoacrylate compounds (2-ethylhexyl-2-cyano-3,3'-diphenylacrylate, ethyl-2-cyano-3,3'-diphenylacrylate, etc.). One type of ultraviolet absorber may be used alone, or two or more types may be used in combination.The amount of the ultraviolet absorber used is preferably 5 parts by mass or less, more preferably 0.1 to 1 part by mass, based on 100 parts by mass of the adhesive composition (X) from the viewpoint of ultraviolet absorption effect and adhesive strength.

[0073] Examples of plasticizers include hydrocarbons [process oil, liquid polybutadiene, liquid polyisobutylene, liquid polyisoprene, liquid paraffin, chlorinated paraffin, paraffin wax, copolymers of ethylene and α-olefins (carbon number 3 to 20) (weight ratio 0.1 / 99.9 to 99.9 / 0.1) oligomers (weight average molecular weight 5,000 to 100,000) and copolymers of propylene and α-olefins (carbon number 4 to 20) (weight ratio 0.1 / 99.9 to 99.9 / 0 1) Oligomers (weight average molecular weight 5,000 to 100,000); chlorinated paraffins; esters (phthalate esters [diethyl phthalate (DEP), dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DOP), didecyl phthalate, dilauryl phthalate, distearyl phthalate, and diisononyl phthalate, etc.], adipate esters [di(2-ethylhexyl) adipate (DOA), dioctyl adipate, etc.] and sebacic acid esters (dioctyl sebacate, etc.), fatty acid esters (butyl stearate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, behenic acid monoglyceride, cetyl 2-ethylhexanoate, isopropyl palmitate, cholesteryl isostearate, methyl coconut fatty acid, methyl laurate, methyl oleate, methyl stearate, isopropyl myristate, octyldodecyl myristate, myristyl myristate, stearyl stearate, 2-ethylhexyl stearate, isotridecyl stearate, 2-ethylhexanoic acid triglyceride, butyl laurate, octyl oleate, etc.), poly(meth)acrylic acid esters (polybutyl acrylate, poly2-ethylhexyl acrylate, etc.); animal and vegetable oils and fats (linoleic acid, linolenic acid, etc.); and hydrogenated products of those containing hydrogenatable unsaturated double bonds. The plasticizer may be used alone or in combination of two or more. The amount of plasticizer used is preferably 100 parts by mass or less, more preferably 1 to 50 parts by mass, particularly preferably 3 to 40 parts by mass, particularly preferably 5 to 35 parts by mass, and most preferably 10 to 30 parts by mass, per 100 parts by mass of the adhesive composition (X), from the viewpoint of the cohesive strength of the adhesive.

[0074] Examples of tackifiers include terpene resins, terpene phenol resins, phenol resins, aromatic hydrocarbon-modified terpene resins, rosin resins, modified rosin resins, synthetic petroleum resins (aliphatic, aromatic, or alicyclic synthetic petroleum resins, etc.), coumarone-indene resins, xylene resins, styrene-based resins, dicyclopentadiene resins, and hydrogenated products of those having hydrogenatable unsaturated double bonds among these. One tackifier may be used alone, or two or more may be used in combination. Of these, polar ones are preferred from the viewpoint of adhesive strength, with rosin resins, phenol resins, terpene phenol resins, xylene resins and their hydrogenated products being more preferred, and terpene phenol resins and their hydrogenated products being particularly preferred. The amount of tackifier used is preferably 100 parts by mass or less, more preferably 1 to 50 parts by mass, particularly preferably 3 to 40 parts by mass, particularly preferably 5 to 35 parts by mass, and most preferably 10 to 30 parts by mass, per 100 parts by mass of the adhesive composition (X), from the viewpoint of adhesive strength and heat resistance.

[0075] Examples of fillers include carbonates (such as magnesium carbonate and calcium carbonate), sulfates (such as aluminum sulfate, calcium sulfate and barium sulfate), sulfites (such as calcium sulfite), molybdenum disulfide, silicates (such as aluminum silicate and calcium silicate), diatomaceous earth, silica powder, talc, silica and zeolite. The fillers are preferably fine particles having a volume average particle size of about 0.01 to 5 μm, and may be used alone or in combination of two or more. The amount of filler used is preferably 250 parts by mass or less, more preferably 0.5 to 100 parts by mass, per 100 parts by mass of the adhesive composition (X), from the viewpoint of the cohesive strength of the adhesive.

[0076] Examples of pigments include inorganic pigments (such as alumina white, graphite, titanium oxide, ultrafine titanium oxide, zinc oxide, black iron oxide, micaceous iron oxide, white lead, white carbon, molybdenum white, carbon black, litharge, lithopone, baryte, cadmium red, cadmium mercury red, red iron oxide, molybdenum red, red lead, yellow lead, cadmium yellow, barium yellow, strontium yellow, titanium yellow, titanium black, chromium oxide green, cobalt oxide, cobalt green, cobalt-chromium green, ultramarine, Prussian blue, cobalt blue, cerulean blue, manganese purple, and cobalt purple) and organic pigments (such as shellac, insoluble azo pigments, soluble azo pigments, condensed azo pigments, phthalocyanine blue, and dye lake). The pigments are preferably fine particles with a volume average particle size of about 0.01 to 5 μm, and may be used alone or in combination of two or more. The amount of pigment used is preferably 250 parts by mass or less, more preferably 0.1 to 50 parts by mass, based on 100 parts by mass of the adhesive composition (X), from the viewpoint of the cohesive strength of the adhesive.

[0077] Examples of reaction accelerators include metal catalysts such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin dimaleate; tertiary amines such as 1,8-diaza-bicyclo(5,4,0)undecene-7 and 1,5-diazabicyclo(4,3,0)nonene-5,6-dibutylamino-1,8-diazabicyclo(5,4,0)undecene-7; and reactive tertiary amines such as triethanolamine. These may be used alone or in combination of two or more.

[0078] <Adhesive> The pressure-sensitive adhesive of the present invention comprises an acrylic-urethane composite resin (C) in which a block (A) of a copolymer of the (meth)acrylate compound and a block (B) of a urethane compound are linked by a chain transfer agent residue formed by removing a hydrogen atom from the hydroxyl group of a chain transfer agent having a hydroxyl group. The weight proportion of the acrylic-urethane composite resin (C) in the adhesive is preferably 75 to 100 mass %, more preferably 80 to 100 mass %, and particularly preferably 85 to 100 mass %, based on the weight of the adhesive.

[0079] <Acrylic-urethane composite resin (C)> In the present invention, the acrylic-urethane composite resin (C) may have a structure in which a polymer block (A) of a (meth)acrylate compound and a block (B) of a urethane compound are linked by a chain transfer agent residue formed by removing a hydrogen atom from the hydroxyl group of a chain transfer agent having a hydroxyl group, and the method for producing the acrylic-urethane composite resin (C) is not limited. However, from the viewpoint of adhesiveness, the acrylic-urethane composite resin (C) is preferably a resin obtained by a urethanization reaction between a precursor of the polymer block (A) of the (meth)acrylate compound having a chain transfer agent residue having a hydroxyl group and a precursor of the urethane compound block (B) having an isocyanate group. More preferably, it can be produced by the following method. First, a urethane prepolymer (a precursor of the urethane compound block (B)) containing an isocyanate group is synthesized by reacting a polyol with a polyisocyanate. Next, a (meth)acrylate compound and a chain transfer agent are chain-transfer polymerized in the presence of a polymerization initiator to synthesize a poly(meth)acrylate (a precursor of the (meth)acrylate compound polymer block (A)) containing a hydroxyl group derived from the chain transfer agent. The resulting urethane prepolymer (a precursor of the urethane compound block (B)) and poly(meth)acrylate (a precursor of the (meth)acrylate compound polymer block (A)) are then mixed with a catalyst, if necessary, to adjust the reactivity, to obtain an acrylic-urethane composite resin (C). Although all of these reactions may be carried out using a solvent, it is preferable to carry out the production without using a solvent from the viewpoint of odor and workability. When a solvent is used, it is preferable to remove the solvent under reduced pressure or normal pressure during the reaction or after completion of the reaction.

[0080] The temperature during synthesis of the urethane prepolymer having an isocyanate group {the precursor of the urethane compound block (B)} is preferably 40 to 90°C, more preferably 50 to 75°C, and the reaction time is preferably 1 to 5 hours, more preferably 1 to 3 hours.

[0081] The temperature during synthesis of the hydroxyl-containing poly(meth)acrylate {precursor of block (A) of the (meth)acrylate compound polymer} is preferably 70 to 90°C, more preferably 75 to 85°C, and the reaction time is preferably 1 to 15 hours, more preferably 3 to 10 hours.

[0082] The temperature when synthesizing the acrylic-urethane composite resin (C) by mixing a urethane prepolymer having an isocyanate group (a precursor of the block (B) of the urethane compound) with a poly(meth)acrylate having a hydroxyl group (a precursor of the block (A) of the polymer of the (meth)acrylate compound) is preferably 50 to 150°C, more preferably 50 to 130°C, and the reaction time is preferably 1 to 5 minutes, more preferably 1 to 3 minutes.

[0083] When a poly(meth)acrylate having a hydroxyl group {a precursor of block (A) of a polymer of a (meth)acrylate compound} is reacted with a urethane prepolymer having an isocyanate group {a precursor of block (B) of a urethane compound}, the ratio of the number of moles of isocyanate groups of the precursor of block (B) of a urethane compound to the number of moles of active hydrogen-containing groups of the precursor of block (A) of a polymer of a (meth)acrylate compound (number of moles of isocyanate groups / number of moles of active hydrogen-containing groups) is 0.1 to 3.0, preferably 0.5 to 2.5, and more preferably 1.0 to 2.0, from the viewpoint of reactivity.

[0084] In the present invention, the content of the chain transfer agent residue as a constituent unit of the acrylic-urethane hybrid resin (C) is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, and even more preferably 1 to 3 parts by mass, based on 100 parts by mass of the acrylic-urethane hybrid resin (C), from the viewpoint of adhesiveness.

[0085] In the present invention, the content of the urethane compound block (B) as a constituent unit of the acrylic-urethane hybrid resin (C) is preferably 0.5 to 25 parts by mass, more preferably 5 to 20 parts by mass, and even more preferably 10 to 20 parts by mass, from the viewpoint of reactivity, relative to 100 parts by mass of the acrylic-urethane hybrid resin (C).

[0086] In the present invention, the content of the (meth)acrylate compound polymer block (A) as a constituent unit of the acrylic-urethane hybrid resin (C) is preferably 70 to 99 parts by mass, more preferably 75 to 95 parts by mass, and even more preferably 80 to 90 parts by mass, based on 100 parts by mass of the acrylic-urethane hybrid resin (C), from the viewpoint of adhesiveness.

[0087] <Other ingredients> In addition to the acrylic-urethane composite resin (C), the adhesive of the present invention may contain other components such as antioxidants, cure retarders, UV absorbers, plasticizers, tackifiers, fillers, and pigments, provided that the effects of the present invention are not impaired. Examples of other components include the same components as those listed as other components in the pressure-sensitive adhesive composition (X).

[0088] <Adhesive sheet> The uses of the pressure-sensitive adhesive composition (X) and pressure-sensitive adhesive of the present invention are not particularly limited. For example, the pressure-sensitive adhesive composition (X) can be applied to a substrate film such as a polyester film or a polyolefin film, and in the case of the pressure-sensitive adhesive composition (X), cured (urethane reaction) to obtain a pressure-sensitive adhesive sheet, which can be used for medical pressure-sensitive adhesive tapes such as surgical tapes, taping tapes, and adhesive plasters, surface protection films for optical components, etc. The present invention also encompasses a pressure-sensitive adhesive sheet obtained using the pressure-sensitive adhesive composition (X) of the present invention.

[0089] Specific examples of methods for forming the pressure-sensitive adhesive sheet include the following methods. For coating the substrate film with the pressure-sensitive adhesive composition (X), a slot die coater, gravure coater, reverse roll coater, comma coater, spin coater, curtain coater, slot coater, bar coater, comma coater, die coater, knife coater, etc. may be used. The amount of pressure-sensitive adhesive composition (X) applied during coating (solid content) is preferably 0.5 to 300 g / m 2 , more preferably 1 to 200 g / m 2 , particularly preferably 10 to 100 g / m 2 is.

[0090] The coating temperature of the pressure-sensitive adhesive composition (X) when it is applied to the substrate film is preferably 10 to 160°C, more preferably 25 to 130°C, from the viewpoints of coatability and suppression of thermal degradation, and the viscosity of the pressure-sensitive adhesive composition (X) at the coating temperature at 25°C is preferably 100,000 mPa·s or less, more preferably 30,000 mPa·s or less, particularly preferably 20,000 mPa·s or less, from the viewpoints of formability (ability to apply thick coatings and absence of appearance defects such as warping and sink marks after curing) and coatability. The viscosity in the present invention can be measured using a B-type viscometer in accordance with JIS-K7117-1. After coating, the pressure-sensitive adhesive composition (X) is cured at 10 to 50° C. for 20 to 150 hours, whereby the pressure-sensitive adhesive composition (X) is completely cured (urethane reaction). [Example]

[0091] The present invention will be described in more detail below with reference to examples, but the scope of the invention is not limited by these examples. Unless otherwise specified, "parts" and "%" in the examples represent "parts by mass" and "% by mass", respectively.

[0092] [Production of precursor of block (A) of polymer of (meth)acrylate compound] <Production Example 1> A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel and a nitrogen gas inlet tube was charged with 50 parts of ethyl acetate as a solvent and heated to 77°C. Next, under solvent reflux, while blowing nitrogen into the reaction vessel, a monomer blend solution (100 parts of n-butyl acrylate), initiator solution 1 (a solution prepared by dissolving 0.05 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) [hereinafter sometimes abbreviated as V-65] in 10 parts of ethyl acetate), and a chain transfer agent (4 parts of 3-mercapto-1,2-propanediol) were continuously added dropwise using a dropping funnel over a period of 3 hours to carry out radical polymerization. After the dropwise addition, initiator solution 2 (a solution of 0.1 parts of V-65 in 10 parts of ethyl acetate) was continuously added over 1 hour using a dropping funnel while stirring the system at the same temperature. After further polymerization was continued for 1 hour under solvent reflux, the mixture was heated to 130°C under reduced pressure to distill off the ethyl acetate, yielding a precursor of block (A-1) of the (meth)acrylate compound polymer. The weight-average molecular weight (Mw) of the precursor of the (meth)acrylate compound polymer block (A-1) was 5,000, the hydroxyl value was 41 mgKOH / g, the glass transition temperature (Tg) was -38°C, and the viscosity at 25°C was 3,000 mPa·s.

[0093] <Production Examples 2 to 6 and Comparative Production Examples 1 and 2> Precursors of blocks (A-2) to (A-6) and precursors of blocks (A'-1) to (A'-2) of the polymer of each (meth)acrylate compound were obtained in the same manner as in Production Example 1, except for following Table 1. The results are shown in Table 1.

[0094] [Table 1]

[0095] [Production of precursor of urethane compound block (B)] <Production Example 7> A four-neck flask equipped with a reflux condenser, stirrer, and thermometer was charged with 12 parts of polyoxypropylene triol, 40 parts of 4,4'-MDI, and 28 parts of a 50 / 50 mixture of 2,4'-MDI and 4,4'-MDI, and the mixture was allowed to react at 75°C for 3 hours. Then, 20 parts of carbodiimide-modified 4,4'-MDI was added to obtain a precursor of urethane compound block (B-1). The precursor of urethane compound block (B-1) had an isocyanate group content of 22.5% and a viscosity of 5,500 mPa·s.

[0096] <Production Examples 8-11> Precursors of urethane compound blocks (B-2) to (B-5) were obtained in the same manner as in Production Example 7, except for following Table 2. The results are shown in Table 2.

[0097] [Table 2]

[0098] <Examples 1 to 10 and Comparative Examples 1 and 2> The adhesive base consisted of precursors of (meth)acrylate polymer blocks (A-1) to (A-6) and (A'-1) to (A'-2), a curing agent consisting of precursors of urethane compound blocks (B-1) to (B-5), a catalyst (D-1) consisting of Neostan U-600, and a cure retarder (E-1) consisting of 2,4-pentanedione. The components were mixed in the amounts shown in Table 3 and kneaded at 23°C for 0.2 hours to obtain adhesive composition (X). The resulting adhesive composition (X) was applied to a 25 μm-thick polyethylene terephthalate film using a slot die coater to a film thickness of 35 μm (solids equivalent), and then dried at 130°C for 3 minutes to obtain an adhesive containing an acrylic-urethane composite resin (C). The resulting adhesive was then cured at 50°C for 4 days to obtain an adhesive sheet.

[0099] [Table 3]

[0100] The contents of each main ingredient listed in Tables 1 to 3 are as follows: [(Meth)acrylate compounds] Methyl acrylate: Mitsubishi Chemical Corporation n-Butyl acrylate: Nippon Shokubai Co., Ltd. 2-Ethylhexyl acrylate: Nippon Shokubai Co., Ltd. Cyclohexyl acrylate: "Viscoat #155" manufactured by Osaka Organic Chemical Industry Co., Ltd. Benzyl acrylate: "Viscoat #160" manufactured by Osaka Organic Chemical Industry Co., Ltd. 2-Hydroxyethyl acrylate: Osaka Organic Chemical Industry Co., Ltd. [Chain transfer agent] 3-Mercapto-1,2-propanediol: manufactured by Tokyo Chemical Industry Co., Ltd. 2-Aminoethanethiol: manufactured by Tokyo Chemical Industry Co., Ltd. [Polyol] Polyoxypropylenetriol-1: Sannix GP-250 (hydroxyl value 670 mg KOH / g) manufactured by Sanyo Chemical Industries, Ltd. Polyoxypropylenetriol-2: Sannix GP-3000 (hydroxyl value 56 mg KOH / g) manufactured by Sanyo Chemical Industries, Ltd. Polypropylene glycol: Sannix PP-1000 (hydroxyl value 112 mg KOH / g) manufactured by Sanyo Chemical Industries, Ltd. Castor oil-based polyester polyol: Toyokuni Oil Mills "HS2P-080" (hydroxyl value 95 mg KOH / g) [Polyisocyanate] 4,4'-MDI: "Millionate MT" manufactured by Tosoh Corporation 2,4'-MDI / 4,4'-MDI = 50 / 50 mixture: "Lupranate MI" manufactured by BASF INOAC Polyurethanes Ltd. Carbodiimide-modified 4,4'-MDI: "Lupranate MM103" manufactured by BASF INOAC Polyurethanes Co., Ltd. Hexamethylene diisocyanate: Tosoh Corporation [catalyst] Neostan U-600: manufactured by Nitto Kasei Co., Ltd. [Cure retarder] 2,4-Pentanedione: Fujifilm Wako Pure Chemical Industries, Ltd.

[0101] <Method for evaluating kneadability> The viscosity (25°C) of the pressure-sensitive adhesive composition (X) was measured immediately after preparation (within 10 minutes after kneading for 0.2 hours at 23°C) using a Brookfield viscometer and evaluated according to the following criteria. A smaller value indicates better kneadability. <Evaluation criteria> ◎:20,000mPa·s or less ○: Over 20,000 mPa·s and less than 30,000 mPa·s △:30,000mPa·s or more

[0102] <How to evaluate coatability> The appearance of the coating film immediately after the pressure-sensitive adhesive composition (X) was applied using a slot die coater was evaluated according to the following criteria. ◎: The coating surface is uniform and free of streaks, and the coating does not contain any air bubbles. ◯: The coating surface is uniform and free of streaks, but air bubbles are visible in the coating △: The coating surface is uneven or has streaks, and bubbles are visible in the coating.

[0103] <Method for evaluating adhesive strength> A pressure-sensitive adhesive sheet test piece measuring 100 mm x 25 mm in plan view was cut out from the pressure-sensitive adhesive sheet. In an atmosphere of 23°C, the 180° peel strength of the pressure-sensitive adhesive film test piece against a SUS plate was measured under conditions of a width of 25 mm and a pulling speed of 300 mm / min, based on the "Test method for adhesive tapes and adhesive sheets" specified in JIS Z0237-2009.

[0104] <Method for evaluating holding power> A pressure-sensitive adhesive sheet test piece measuring 100 mm × 12 mm in plan view was cut from the pressure-sensitive adhesive sheet. A stainless steel plate measuring 100 mm × 100 mm in plan view was also prepared. The pressure-sensitive adhesive sheet and the stainless steel plate were stacked so that the adhesive surface of the pressure-sensitive adhesive sheet was in contact with the stainless steel plate, and the contact area was 12 mm × 12 mm in plan view. Next, a roller was applied with a load of 2 kg to the polyethylene terephthalate film, and the roller was moved back and forth over the polyethylene terephthalate film once. This resulted in the pressure-sensitive adhesive sheet and the stainless steel plate being bonded together to obtain a laminate. This laminate was left standing in an atmosphere at 40°C for 30 minutes. Next, in a 40°C atmosphere, the stainless steel plate was stood upright so that the part in contact with the adhesive sheet was facing downward, and in this state, a downward load of 1 kg was applied to the upper end of the adhesive sheet at the lower end of the 88 mm x 12 mm part of the stainless steel plate where the adhesive sheet was not overlapping, for 24 hours. Next, the downward positional deviation (unit: mm) of the adhesive sheet relative to the stainless steel plate was measured and evaluated according to the following criteria. Note that a smaller value indicates a higher holding power. <Evaluation criteria> A: 0.5mm or less B: Over 0.5mm and 2.0mm or less C: Over 2.0 mm [Industrial Applicability]

[0105] The pressure-sensitive adhesive composition of the present invention is solvent-free and has low viscosity, and therefore has good coatability and kneadability, and is also excellent in adhesiveness, making it extremely useful and usable in a wide range of applications, such as optical components, automotive components, building materials, and medical applications.

Claims

1. A pressure-sensitive adhesive composition (X) containing a precursor of a block (A) of a polymer of a (meth)acrylate compound and a precursor of a block (B) of a urethane compound, A pressure-sensitive adhesive composition (X), wherein the precursor of the block (A) of the polymer of the (meth)acrylate compound has a chain transfer agent residue having a hydroxyl group.

2. The pressure-sensitive adhesive composition (X) according to claim 1, wherein a precursor of the block (A) of the polymer of the (meth)acrylate compound has a hydroxyl group, and the precursor of the block (A) of the copolymer of the (meth)acrylate compound has a hydroxyl value of 10 to 50 mgKOH / g.

3. The pressure-sensitive adhesive composition (X) according to claim 1, wherein the precursor of the block (A) of the polymer of the (meth)acrylate compound has a weight average molecular weight (Mw) of 4,000 to 15,000 and a molecular weight distribution {weight average molecular weight (Mw) / number average molecular weight (Mn)} of 1.5 to 2.

5.

4. The pressure-sensitive adhesive contains an acrylic-urethane composite resin (C) in which a block (A) of a copolymer of the (meth)acrylate compound and a block (B) of the urethane compound are linked by a chain transfer agent residue formed by removing a hydrogen atom from the hydroxyl group of a chain transfer agent having a hydroxyl group.

5. The content of the block (A) of a polymer of a (meth)acrylate compound as a structural unit in 100 parts by mass of the acrylic-urethane composite resin (C) is 70 to 99 parts by mass. The adhesive according to claim 4.

6. A pressure-sensitive adhesive sheet using the pressure-sensitive adhesive according to claim 4 or 5.

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