Curable composition for adhesive, adhesive, and adhesive sheet

Abstract

A curable composition (S) for an adhesive according to the present invention contains: a urethane prepolymer (P) that has a hydroxyl group and a (meth)acryloyl group; a crosslinking agent (C); a compound (D) that has a (meth)acryloyl group other than the urethane prepolymer (P); a photopolymerization initiator (E); and a compound (F) that has an active methylene group, wherein the urethane prepolymer (P) that has a hydroxyl group and a (meth)acryloyl group is obtained by reacting a polyisocyanate component (B) and a hydroxyl group-containing component (A) including a hydroxy (meth)acrylate (a1).

Description

Curable composition for pressure-sensitive adhesive, pressure-sensitive adhesive, and pressure-sensitive adhesive sheet

[0001] The present invention relates to a curable composition for a pressure-sensitive adhesive, a pressure-sensitive adhesive, and a pressure-sensitive adhesive sheet.

[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 are required to have good adhesive properties when attached. Adhesion refers to the property of having sufficient adhesive strength to an adherend and not causing defects such as peeling or lifting. On the other hand, if the adhesive strength of a pressure-sensitive adhesive sheet is excessive, the adherend may be damaged, such as cracked or broken, or adhesive residue may remain on the adherend when peeled. Therefore, pressure-sensitive adhesive sheets are required to have appropriate adhesive properties and good reworkability when peeled. Patent Document 1 describes a curable composition for pressure-sensitive adhesives that exhibits adhesive properties upon thermal curing and reduces adhesive properties upon photocuring, thereby enabling re-peeling. However, the curable composition for pressure-sensitive adhesives described in Patent Document 1 has unsatisfactory reworkability. Furthermore, after exhibiting adhesive properties through thermal curing, the composition undergoes photocuring over time, resulting in a decrease in adhesive strength and an inability to maintain good adhesive strength.

[0004] Japanese Patent Application Laid-Open No. 2020-105452

[0005] An object of the present invention is to provide a pressure-sensitive adhesive using a curable composition for pressure-sensitive adhesives, which has excellent reworkability, little adhesive residue on an adherend, and can maintain adhesive strength over a long period of time, and a pressure-sensitive adhesive sheet using the pressure-sensitive adhesive.

[0006] The present inventors have conducted extensive research to solve the above problems and have arrived at the present invention. Specifically, the present invention relates to a curable composition for pressure-sensitive adhesives (S), which contains a urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group, a crosslinking agent (C), a compound (D) other than the urethane prepolymer (P) having a (meth)acryloyl group, a photopolymerization initiator (E), and a compound (F) having an active methylene group, wherein the urethane prepolymer (P) is a urethane prepolymer obtained by reacting a hydroxyl group-containing component (A) containing a hydroxy(meth)acrylate (a1) with a polyisocyanate component (B).

[0007] The adhesive using the pressure-sensitive adhesive curable composition of the present invention and the adhesive sheet using the adhesive have good reworkability, leave little adhesive residue on the adherend, and are less susceptible to deterioration in adhesive strength over time.

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

[0009] <Urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group> The pressure-sensitive adhesive curable composition (S) of the present invention contains a urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group. Hereinafter, the urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group may be referred to as the "urethane prepolymer (P)" or the "urethane prepolymer (P) having a hydroxyl group." The urethane prepolymer (P) can be obtained by reacting a hydroxyl group-containing component (A) containing a hydroxy(meth)acrylate (a1) with a polyisocyanate component (B).

[0010] <Hydroxyl Group-Containing Component (A)> The hydroxyl group-containing component (A) of the present invention contains a hydroxy(meth)acrylate (a1).

[0011] (Hydroxy(meth)acrylate (a1)) Examples of the hydroxy(meth)acrylate (a1) include dipentaerythritol penta(meth)acrylate, pentaerythritol tri(meth)acrylate, glycerin di(meth)acrylate, glycerin mono(meth)acrylate, trimethylolpropane di(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, caprolactone-modified hydroxymono(meth)acrylate, polyethylene glycol- and polypropylene glycol-modified hydroxymono(meth)acrylate, and the like.

[0012] As the hydroxy(meth)acrylate (a1), from the viewpoint of weakening the adhesive strength after irradiation with active energy rays and improving reworkability, a compound having two or more hydroxyl groups and a (meth)acryloyl group is preferred, a compound having two hydroxyl groups and a (meth)acryloyl group is more preferred, and glycerin mono(meth)acrylate is particularly preferred.

[0013] The average number of hydroxyl groups per molecule of the hydroxy(meth)acrylate (a1) is preferably 1.1 to 2.0, and more preferably 1.5 to 2.0, from the viewpoint of the change in adhesive strength before and after irradiation with active energy rays.

[0014] In the present invention, the average number of hydroxyl groups per molecule of the hydroxy(meth)acrylate (a1) can be calculated by the following formula (I): Number of hydroxyl groups per molecule = Mn Ａ ×OHV / 56100 (I) Mn Ａ OHV: number average molecular weight (Mn) of hydroxy(meth)acrylate (a1) OHV: hydroxyl value (mgKOH / g) of hydroxy(meth)acrylate (a1)

[0015] The content of the hydroxy(meth)acrylate (a1) based on the total weight of the hydroxyl group-containing component (A) is preferably 0.2 to 10% by weight, more preferably 2 to 10% by weight, from the viewpoint of the change in adhesive strength before and after irradiation with active energy rays. １ H-NMR and １３ It can be determined by C-NMR.

[0016] Examples of the hydroxyl group-containing component (A) other than the hydroxy(meth)acrylate (a1) include polyether polyols (a2), polyester polyols (a3), polycarbonate polyols (a4), polyolefin polyols (a5), vegetable oil-based polyols (a6), and hydroxyl group-containing amine compounds (a7). These may be used alone or in combination of two or more.

[0017] (Polyether Polyol (a2)) Examples of the polyether polyol (a2) include polymers of methylene oxide, ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, and the like, such as glycols such as polyethylene glycol, polypropylene glycol, poly(ethylene / propylene) glycol, and polytetramethylene glycol; 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.

[0018] Examples of the compound having two or more active hydrogen groups include low molecular weight polyols, aliphatic amine compounds, aromatic amine compounds, and alkanolamines.

[0019] The low molecular weight polyols include those with a molecular formula weight of 500 or less, and examples thereof include difunctional low molecular weight polyols and trifunctional or higher functional low molecular weight polyols.

[0020] 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, 8-octanediol, polyoxyethylene glycol, polyoxypropylene glycol, cyclohexanediol, cyclohexanedimethanol, tricyclodecane dimethanol, cyclopentadiene dimethanol, dimer diol, bisphenol A, bisphenol F, 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.

[0021] 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, polyoxypropylenetriol, trimethylolbutene, trimethylolpentene, trimethylolhexene, trimethylolheptene, trimethyloloctene, trimethylolnonene, trimethyloldecene, trimethylolundecene, and trimethyloldodecanone. hexane, trimethylol tridecene, trimethylol pentadecene, trimethylol hexadecene, trimetrol heptadecene, trimethylol octadecene, 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, trimethylol hexene, 1,2,3-octanetriol, 1,3,7-octanetriol, 3,7-dimethyl-1,2,3-octanol 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-trimethylolisoheptadecane, 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.

[0022] 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. The content of polyether polyol (a2) in the constituent monomers of the urethane prepolymer (P) is preferably 40 to 85% by weight, based on the total weight of the monomers constituting the urethane prepolymer (P).

[0023] (Polyester Polyol (a3)) Examples of the polyester polyol (a3) ​​include polyester polyols obtained by condensation reaction of the above-mentioned low-molecular-weight polyols with a dibasic acid component. Examples of the dibasic acid component include aliphatic and 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.

[0024] Alternatively, the polyester polyol may be a polyester polyol obtained by ring-opening polymerization of a cyclic ester compound of a lactone such as ε-caprolactone, poly(β-methyl-γ-valerolactone), polyvalerolactone, etc. The content of the polyester polyol (a3) ​​in the constituent monomers of the urethane prepolymer (P) is preferably 0 to 35% by weight based on the total weight of the monomers constituting the urethane prepolymer (P).

[0025] (Polycarbonate polyol (a4)) Examples of the polycarbonate polyol (a4) include those obtained by reacting the above-mentioned low-molecular-weight polyol with a carbonate compound such as a dialkyl carbonate, an alkylene carbonate, or a diaryl carbonate. As the dialkyl carbonate, dimethyl carbonate, diethyl carbonate, or the like can be used. As the alkylene carbonate, ethylene carbonate, or the like can be used. As the diaryl carbonate, diphenyl carbonate, or the like can be used.

[0026] (Polyolefin polyol (a5)) Examples of the polyolefin polyol (a5) 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.

[0027] (Vegetable Oil-Based Polyol (a6)) Examples of the vegetable oil-based polyol (a6) include polyols made from vegetable oils (castor oil, soybean oil, etc.) or fatty acids (dimer acids) obtained from vegetable oils.

[0028] (Hydroxyl Group-Containing Amine Compound (a7)) Examples of the hydroxyl group-containing amine compound (a7) include ethanolamine, diethanolamine, 1-amino-2-propanol, 2-amino-2-methylpropanol, 2-(2-aminoethylamino)ethanol, and triethanolamine. The content of the hydroxyl group-containing amine compound (a7) in the constituent monomers of the urethane prepolymer (P) is preferably 0 to 5 wt % based on the total weight of the monomers constituting the urethane prepolymer (P).

[0029] The hydroxyl group-containing component (A) preferably contains a hydroxy(meth)acrylate (a1), a polyether polyol (a2), and a polyester polyol (a3), or a hydroxy(meth)acrylate (a1), a polyether polyol (a2), and a hydroxyl group-containing amine compound (a7). When the hydroxyl group-containing component (A) contains the hydroxyl group-containing amine compound (a7), the adhesive strength of the cured product of the pressure-sensitive adhesive curable composition (S) is increased, which is preferable.

[0030] The number average molecular weight (Mn) of the hydroxyl group-containing component (A) is preferably 50 to 10,000, more preferably 400 to 6,000.

[0031] The number average molecular weight (Mn) of the hydroxyl group-containing component (A) and the weight average molecular weight (Mw) of the urethane prepolymer (P) in the present invention can be measured by gel permeation chromatography, for example, under the following conditions: Apparatus: "HLC-8120GPC" [manufactured by Tosoh Corporation] Column: "Guard column HXL-H" (1 column) and "TSKgel GMHXL" (2 columns) [both manufactured by Tosoh Corporation] Sample solution: 0.25 wt % tetrahydrofuran solution Solution injection amount: 100 μl Flow rate: 1 ml / min Measurement temperature: 40° C. Detector: refractive index detector Reference material: standard polystyrene

[0032] The hydroxyl group-containing component (A) 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 or introducing various functional groups.

[0033] <Polyisocyanate Component (B)> Examples of the polyisocyanate component (B) constituting the urethane prepolymer (P) include aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and modified polyisocyanates. These may be used alone or in combination of two or more.

[0034] Examples of aromatic diisocyanates include 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4-diphenylmethane diisocyanate (2,4'-MDI), 2,2'-diphenylmethane diisocyanate (2,2'-MDI), 1,5-naphthalene diisocyanate, ... Examples of the isocyanate include phthalene 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.

[0035] Examples of aliphatic diisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), 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, pentamethylene diisocyanate, and trimethylhexamethylene diisocyanate.

[0036] 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.

[0037] Examples of modified polyisocyanates include modified products of the aromatic diisocyanates, modified products of the aliphatic diisocyanates, and modified products of the alicyclic diisocyanates (such as modified products containing a urethane group, a carbodiimide group, an allophanate group, a urea group, a biuret group, a uretdione group, a uretoimine group, an isocyanurate group, or an oxazolidone group; those having a free isocyanate group content of preferably 8 to 33% by weight, more preferably 10 to 30% by weight, and particularly preferably 12 to 29% by weight), such as polyfunctionally modified MDI (such as urethane-modified MDI, carbodiimide-modified MDI, and trihydrocarbyl phosphate-modified MDI), polyfunctional urethane-modified TDI, polyfunctional biuret-modified HDI, polyfunctional isocyanurate-modified HDI, and polyfunctional isocyanurate-modified IPDI.

[0038] As the polyisocyanate component (B), from the viewpoint of coloring the pressure-sensitive adhesive curable composition (S), the pressure-sensitive adhesive (U) and the pressure-sensitive adhesive sheet (T), aliphatic diisocyanates and alicyclic diisocyanates are preferred, and hexamethylene diisocyanate and isophorone diisocyanate are more preferred.

[0039] The urethane prepolymer (P) may be used alone or in combination of two or more kinds.

[0040] The reaction between the hydroxyl group-containing component (A) and the polyisocyanate component (B) can be carried out using a known urethane-forming reaction. By making the hydroxyl groups in the hydroxyl group-containing component (A) excess relative to the isocyanate groups in the polyisocyanate component (B), a urethane prepolymer having hydroxyl groups at its terminals can be obtained. From the viewpoint of reactivity, the molar ratio of isocyanate groups to hydroxyl groups during the reaction (number of NCO moles / number of OH moles) is preferably 0.5 to 0.99, more preferably 0.6 to 0.95. The urethane-forming reaction may also use a catalyst, polymerization inhibitor, and solvent, which will be described later.

[0041] (Catalyst) Known metal catalysts, amine catalysts, and the like can be used as the catalyst. Examples of metal catalysts include dibutyltin dilaurate, tin octoate, dibutyltin di(2-ethylhexoate), dibutyltin dibutyllaurate, lead 2-ethylhexoate, 2-ethylhexyl titanate, titanium ethyl acetate, iron 2-ethylhexoate, cobalt 2-ethylhexoate, zinc naphthenate, cobalt naphthenate, and tetra-n-butyltin. In addition to the above, compounds containing bismuth can also be used as the metal catalyst. Examples of compounds containing bismuth include organic bismuth compounds (e.g., bismuth-based catalysts used as urethanization catalysts [e.g., salts of bismuth and monocarboxylic acids having 1 to 12 carbon atoms, bismuth alkoxides, and chelate compounds of bismuth and β-diketones such as acetylacetone]), inorganic bismuth compounds, and the like. Examples of salts of bismuth and monocarboxylic acids having 1 to 12 carbon atoms include bismuth 2-ethylhexoate and bismuth octoate. Examples of amine catalysts include tertiary amines such as tetramethylbutanediamine. Of these catalysts, from the viewpoint of controlling the reaction of the urethane prepolymer (P), organic bismuth compounds are preferred, more preferably salts of bismuth and monocarboxylic acids having 1 to 12 carbon atoms, and even more preferably bismuth octoate. The amount of catalyst used is preferably in the range of 0.001 to 1.00 parts by mass per 100 parts by mass of the hydroxyl group-containing component (A).

[0042] (Polymerization inhibitor) Examples of the polymerization inhibitor include 2,6-di-t-butyl-4-methylphenol, 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid stearate, 2,2'-methylenebis(4-methyl-6-t-butylphenol), tetrakis(methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate)methane, 4,4'-thiobis(3-methyl-6-t-butylphenol), 2,5-di-t-butylhydrogen Examples of antioxidants include hindered phenols such as quinone; sulfur-based antioxidants such as dilauryl thiodipropionate and distearyl thiodipropionate; phosphorus-based antioxidants such as triphenyl phosphite, tris(nonylphenyl)phosphite, distearyl pentaerythritol diphosphite and tetra(tridecyl)-1,1,3-tris(2-methyl-5-t-butyl-4-hydroxyphenyl)butane diphosphite; and hydroquinone.

[0043] (Solvent) Examples of the solvent include ketone solvents (e.g., acetone and methyl ethyl ketone), ester solvents [e.g., ethyl acetate, dibasic acid ester (DBE)], ether solvents (e.g., tetrahydrofuran), amide solvents (e.g., N,N-dimethylformamide and N-methylpyrrolidone), and aromatic hydrocarbon solvents (e.g., toluene). These solvents may be used alone or in combination of two or more.

[0044] The hydroxyl value of the urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group is preferably 3 to 20 mgKOH / g, more preferably 5 to 20 mgKOH / g, and even more preferably 5 to 15 mgKOH / g, from the viewpoint of adhesive strength before irradiation with active energy rays. In the present invention, the hydroxyl value is a value measured in accordance with JIS K0070.

[0045] The weight average molecular weight (Mw) of the urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group is from 50,000 to 300,000, and preferably from 80,000 to 250,000, from the viewpoints of handleability and curability. The content of the urethane prepolymer (P) in the curable pressure-sensitive adhesive composition (S) is preferably from 10 to 70% by weight, and more preferably from 10 to 50% by weight.

[0046] <Crosslinking agent (C)> The pressure-sensitive adhesive curable composition (S) of the present invention contains a crosslinking agent (C). The crosslinking agent (C) has the function of reacting with the urethane prepolymer (P) by heat or the like to crosslink it.

[0047] The crosslinking agent (C) is not particularly limited as long as it is a compound capable of undergoing a crosslinking reaction with the urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group. Examples include isocyanate-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, and peroxides. Here, peroxide refers to a compound having a peroxide structure "-O-O-" within its molecular structure. These crosslinking agents (C) may be used alone or in combination of two or more. When two or more types are used, two or more types of the same type may be combined, or one or more types of different types may be combined.

[0048] As the isocyanate-based crosslinking agent, a compound having an isocyanate group can be used, including the polyisocyanates exemplified above as the polyisocyanate component (B).

[0049] The carbodiimide crosslinking agent is not particularly limited, and any known carbodiimide compound can be used. Examples of the carbodiimide compound include high-molecular-weight polycarbodiimides produced by decarboxylation condensation of diisocyanate in the presence of a carbodiimidization catalyst. Examples of diisocyanates used in the decarboxylation condensation reaction include 4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 4,4'-diphenylether diisocyanate, 3,3'-dimethyl-4,4'-diphenylether diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and tetramethylxylylene diisocyanate. Furthermore, examples of the carbodiimidization catalyst used in the decarboxylation condensation reaction include phospholene oxides such as 1-phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-3-methyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, and 3-phospholene isomers thereof.

[0050] The oxazoline crosslinking agent is not particularly limited, and known oxazoline compounds can be used. Examples of oxazoline compounds include oxazoline group-containing polymers. Specific examples of oxazoline compounds include oxazoline group-containing acrylic polymers and oxazoline group-containing acrylic / styrene polymers. Examples of oxazoline group-containing acrylic polymers include oxazoline group-containing acrylic polymers that have a main chain composed of an acrylic skeleton and have oxazoline groups on side chains of the main chain. Examples of oxazoline group-containing acrylic / styrene polymers include oxazoline group-containing acrylic / styrene polymers that have a main chain composed of an acrylic skeleton and a styrene skeleton and have oxazoline groups on side chains of the main chain. Examples of oxazoline groups include 2-oxazoline groups, 3-oxazoline groups, and 4-oxazoline groups.

[0051] The epoxy crosslinking agent is not particularly limited, and known epoxy compounds can be used. Examples of epoxy compounds include diglycidyl compounds. Examples of diglycidyl compounds include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, and 1,6-hexanediol diglycidyl ether. In addition to diglycidyl compounds, examples of epoxy compounds include trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, and diglycerol polyglycidyl ether. Diglycidyl compounds are preferred because they facilitate mixing operations when producing the pressure-sensitive adhesive curable composition (S).

[0052] The aziridine crosslinking agent is not particularly limited, and known aziridine compounds can be used. Examples of the aziridine compound include polyfunctional aziridine compounds having multiple aziridine rings. Examples of the polyfunctional aziridine compound include compounds disclosed in U.S. Pat. No. 3,225,013, U.S. Pat. No. 4,490,505, U.S. Pat. No. 5,534,391, and JP-A-2003-104970. As the polyfunctional aziridine compound, a trifunctional aziridine compound (a compound having three aziridine rings) can be suitably used. Examples of trifunctional aziridine compounds include trimethylolpropane tris[3-aziridinyl propionate], trimethylolpropane tris[3-(2-methyl-aziridinyl)-propionate], trimethylolpropane tris[2-aziridinyl butyrate], pentaerythritol tris-3-(1-aziridinyl propionate), and pentaerythritol tetrakis-3-(1-aziridinyl propionate).

[0053] The peroxide is not particularly limited, and known peroxides can be used. Examples of peroxides include diisopropyl peroxydicarbonate, bis(2-ethylhexyl)peroxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate (also known as bis(4-t-butylcyclohexyl)peroxydicarbonate), bis-sec-butyl peroxydicarbonate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, bis-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, bis(4-methylbenzoyl)peroxide, dibenzoyl peroxide (benzoyl peroxide), and t-butyl peroxybutyrate.

[0054] Among these, from the viewpoint of adhesive strength before irradiation with active energy rays, isocyanate-based crosslinking agents or peroxides are preferred, and isocyanate-based crosslinking agents are more preferred.

[0055] As the isocyanate-based crosslinking agent, from the viewpoints of adhesive strength before irradiation with active energy rays and releasability after irradiation with active energy rays, polyfunctional isocyanurate-modified isocyanates and polyfunctional biuret-modified isocyanates are preferred, and polyfunctional isocyanurate-modified isocyanates are more preferred. Specific examples include HDI-based isocyanurate-type polyisocyanates and HDI-based biuret-type polyisocyanates. These isocyanate-based crosslinking agents can more efficiently promote the polymerization and crosslinking reaction between the urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group.

[0056] The amount of the crosslinking agent (C) added to the pressure-sensitive adhesive curable composition (S) is not particularly limited as long as it is an amount that can promote the polymerization and crosslinking reaction between the crosslinking agent (C) and the urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group.

[0057] When the crosslinking agent (C) contains an isocyanate-based crosslinking agent, the equivalent ratio (NCO / OH) of the total amount of isocyanate groups of the isocyanate-based crosslinking agent to the total amount of hydroxyl groups of the urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group in the curable composition for pressure-sensitive adhesive (S) is preferably 0.01 to 1.2, and more preferably 0.1 to 1.0, from the viewpoints of adhesive strength and releasability before irradiation with active energy rays.

[0058] <Compound (D) Having a (Meth)acryloyl Group Other Than (P)> The pressure-sensitive adhesive curable composition (S) of the present invention contains a compound (D) having a (meth)acryloyl group other than (P). As the compound (D) having a (meth)acryloyl group other than (P), monofunctional (meth)acrylic monomers and polyfunctional (meth)acrylic monomers can be used. These may be used alone or in combination of two or more.

[0059] (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 with an acid anhydride, an alkoxysilane having a (meth)acryloyl group, and a lactone adduct of (meth)acrylic acid. Furthermore, the monofunctional (meth)acrylic monomer may 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.).

[0060] 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.

[0061] Examples of the chain aliphatic alcohols 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-butanediol, 1,8-butanediol, 1,9-butanediol, 2,10-butanediol, 2,11-butanediol, 2,12-butanediol, 2,13-butanediol, 2,14-butanediol, 2,15-butanediol, 2,16-butanediol, 2,17-butanediol, 2,18-butanediol, 2,19-butanediol, 2,20-butanediol, 2,21-butanediol, 2,22-butanediol, 2,23-butanediol, 2,24-butanediol, 2,25-butanediol, 2,26-butanediol, 2,27-butanediol, 2,28-butanediol, 2,29-butanediol, 2,30-butanediol, 2,31-butanediol, 2,32-butanediol, 2,33-butanediol, 2,34-butanediol, 2,35-butanediol, 2, 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.].

[0062] 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.

[0063] 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, benzyl alcohol, and 2,4,5-trimethylphenol.

[0064] Specific examples of the monoesters of the 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, and isopropyl (meth)acrylate. Examples of the acrylates include sodecyl (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, butoxymethyl (meth)acrylate, and glycerin mono(meth)acrylate. Furthermore, with regard to the monoesters of the chain aliphatic alcohols having 1 to 20 carbon atoms and (meth)acrylic acid, examples of compounds in which the hydrogen atoms of the chain aliphatic alcohols having 1 to 20 carbon 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.

[0065] Specific examples of the monoesters of the alicyclic alcohols having 3 to 20 carbon atoms with (meth)acrylic acid include glycidyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-n-butylcyclohexyl (meth)acrylate, bornyl (meth)acrylate, and isobornyl (meth)acrylate.

[0066] 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-trimethylphenyl (meth)acrylate, and phenoxymethyl (meth)acrylate. Specific examples of the monoesters of aromatic alcohols having 6 to 15 carbon atoms with (meth)acrylic acid, in which hydrogen atoms in the aromatic alcohol having 6 to 15 carbon atoms are substituted with halogen atoms, carboxy groups, cyano groups, amino groups, and / or alkylamino groups (dimethylamino groups, diethylamino groups, etc.), include 4-chlorophenyl (meth)acrylate.

[0067] The alkylene oxide used as a raw material for the monoesterification product of (meth)acrylic acid and an alkylene oxide adduct of an alcohol having 1 to 20 carbon atoms includes alkylene oxides having 2 to 4 carbon atoms, and specific examples thereof include ethylene oxide, 1,2- and 1,3-propylene oxide, and 1,2-, 1,3-, 1,4- and 2,3-butylene oxide, etc. 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 with (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, polypropylene oxide monomethyl ether (meth)acrylate, Examples of the methyl ether (meth)acrylate include methyl ether (meth)acrylate, oligopropylene oxide monomethyl ether (meth)acrylate, butoxydiethylene glycol monomethyl ether (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 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.

[0068] Examples of the (meth)acrylic acid ester having a hydroxyl group, which is a raw material for the reaction product of the (meth)acrylic acid ester having a hydroxyl group and an acid anhydride, include the monoesters of (meth)acrylic acid and alcohols having 1 to 20 carbon atoms and the monoesters of (meth)acrylic acid and alkylene oxide adducts of alcohols having 1 to 20 carbon atoms, in which the alcohol having 1 to 20 carbon atoms is a dihydric or higher alcohol. Examples of the acid anhydrides include acid anhydrides 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)acryloyloxyethylhexahydrophthalic 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, and 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 (addition number 1 to 30) mono(meth)acrylate succinic acid ester.

[0069] Examples of the alkoxysilane having a (meth)acryloyl group include trimethoxysilylpropyl (meth)acrylate and trimethylsilylpropyl (meth)acrylate.

[0070] Examples of lactones that can be used as raw materials for the lactone adducts to (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 an alcohol having 1 to 20 carbon atoms is preferably 1 to 15 moles. Examples of lactone adducts to (meth)acrylic acid include ω-carboxy-caprolactone mono(meth)acrylate and ω-carboxy-di-(caprolactone) mono(meth)acrylate.

[0071] Among the above monofunctional (meth)acrylic monomers, 2-hydroxyethyl (meth)acrylate and glycerin mono(meth)acrylate are preferred from the viewpoint of the change in adhesive strength before and after irradiation with active energy rays and the availability of raw materials, and 2-hydroxyethyl acrylate and glycerin monomethacrylate are more preferred. The above monofunctional (meth)acrylic monomers may be used alone or in combination of two or more.

[0072] (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.

[0073] [Bifunctional (meth)acrylic monomer] Examples of the bifunctional (meth)acrylic monomer include an ester of 1 mol of a divalent 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 divalent 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 divalent or higher alcohol selected from the above alcohols having 1 to 20 carbon atoms with 2 mol of (meth)acrylic acid. Furthermore, the bifunctional (meth)acrylic monomer may be a compound obtained by reacting the hydroxyl group of the above ester that has not reacted with (meth)acrylic acid with a carboxylic acid having 2 to 10 carbon atoms (e.g., 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, ) acrylate, ethylene 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, 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.

[0074] [Trifunctional (meth)acrylic monomer] Examples of the trifunctional (meth)acrylic monomer include an esterification product 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 esterification product of 1 mol of an alkylene oxide adduct to 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 esterification product of 1 mol of a lactone adduct to a trivalent or higher alcohol selected from the above-mentioned alcohols having 1 to 20 carbon atoms with 3 mol of (meth)acrylic acid. Furthermore, the trifunctional (meth)acrylic monomer may be a compound obtained by reacting the hydroxyl group of the above-mentioned esterification product that has not reacted with (meth)acrylic acid with a carboxylic acid having 2 to 10 carbon atoms (e.g., 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.

[0075] [Tetrafunctional or higher (meth)acrylic monomer] 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.

[0076] Examples of the tetrafunctional or higher (meth)acrylic monomer include an ester of 1 mol of a tetravalent or higher alcohol selected from the above 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 of a tetravalent or higher alcohol selected from the above 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 of a tetravalent or higher alcohol selected from the above alcohols having 1 to 20 carbon atoms with 4 mols or more of (meth)acrylic acid. Furthermore, the tetrafunctional or higher (meth)acrylic monomer may 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 (e.g., 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.

[0077] Among the above polyfunctional (meth)acrylic monomers, from the viewpoint of curability, trifunctional (meth)acrylic monomers and tetrafunctional or higher functional (meth)acrylic monomers are preferred, tetrafunctional or higher functional (meth)acrylic monomers are more preferred, hexafunctional (meth)acrylic monomers are particularly preferred, and dipentaerythritol hexa(meth)acrylate is most preferred. The above polyfunctional (meth)acrylic monomers may be used alone or in combination of two or more.

[0078] The content of the compound (D) having a (meth)acryloyl group other than the urethane prepolymer (P) in the curable composition for pressure-sensitive adhesive (S) is preferably 1 to 30 parts by mass, more preferably 2 to 15 parts by mass, per 100 parts by mass of the urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group, from the viewpoint of the adhesive strength after irradiation with active energy rays and the change in adhesive strength before and after irradiation with active energy rays.

[0079] <Photopolymerization initiator (E)> The pressure-sensitive adhesive curable composition (S) of the present invention contains a photopolymerization initiator (E). The photopolymerization initiator (E) is not particularly limited, but a known photoradical polymerization initiator or photocationic polymerization initiator can be used, and it is preferable to use a photoradical polymerization initiator.

[0080] Examples of the photopolymerization initiator (E) include 1-hydroxycyclohexyl phenyl ketone (Omnirad 184), oligo(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenylpropanone]), 2,2-dimethoxy-2-phenylacetophenone (Omnirad 651), 2-hydroxy-2-methyl-1-phenylpropan-1-one, diethoxyacetophenone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1, benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin. benzoin isopropyl ether, benzoin n-butyl ether, benzoin phenyl ether, benzil dimethyl ketal, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3'-dimethyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, methylphenyl glyoxylate, benzyl and camphorquinone. Among these, from the viewpoint of adhesive strength after irradiation with active energy rays and change in adhesive strength before and after irradiation with active energy rays, alkylphenone types and benzyl ketal types are preferred, α-hydroxyacetophenone types and benzyl ketal types are more preferred, and 2,2-dimethoxy-2-phenylacetophenone and 1-hydroxycyclohexyl phenyl ketone are particularly preferred. The photopolymerization initiator (E) may be used alone or in combination of two or more types.

[0081] Commercially available photopolymerization initiators (E) include EsacureOne (oligo(2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenylpropanone]), manufactured by IGM Resins B.V.), Omnirad 651 (2,2-dimethoxy-2-phenylacetophenone), manufactured by IGM Resins B.V.), Omnirad 184 (1-hydroxycyclohexylphenylketone), manufactured by IGM Resins B.V.), Omnirad 1173 (2-hydroxy-2-methyl-1-phenylpropanone), manufactured by IGM Resins B.V.), and Omnirad 819 (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide), manufactured by IGM Resins B.V.). Examples of suitable methyl benzoyl esters include methyl benzoyl diphenyl phosphine oxide (manufactured by IGM RESINS BV) and Omnirad TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide, manufactured by IGM RESINS BV).

[0082] The content of the photopolymerization initiator (E) in the pressure-sensitive adhesive curable composition (S) is preferably 0.1 to 10 parts by mass, and more preferably 0.2 to 5 parts by mass, relative to 100 parts by mass of the pressure-sensitive adhesive curable composition (S), from the viewpoint of the adhesive strength after irradiation with active energy rays and the change in adhesive strength before and after irradiation with active energy rays.

[0083] <Compound (F) Having an Active Methylene Group> The pressure-sensitive adhesive curable composition (S) of the present invention contains a compound (F) having an active methylene group. In the present application, the active methylene group refers to a methylene group (—CH ２-), those which have a carbonyl group at the adjacent position and are reactive to nucleophiles. Examples of compounds (F) having an active methylene group 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), dibenzoylmethane, and 2-furoylbenzoyl Examples of the compound (F) include β-diketones such as acetylmethane; β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, 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; and dialkyl malonates such as dimethyl malonate, diethyl malonate, methyl ethyl malonate, diisopropyl malonate, and dibutyl malonate. Among these, β-diketones are preferred, and acetylacetone is more preferred, from the viewpoint of maintaining adhesive strength until irradiation with active energy rays. The compound (F) having an active methylene group may be used alone or in combination of two or more.

[0084] The content of the compound (F) having an active methylene group in the pressure-sensitive adhesive curable composition (S) is preferably 0.1 to 10 parts by mass, and more preferably 0.2 to 5 parts by mass, per 100 parts by mass of the pressure-sensitive adhesive curable composition (S), from the viewpoint of maintaining adhesive strength until irradiation with active energy rays.

[0085] <Elemental Bismuth> The pressure-sensitive adhesive curable composition (S) of the present invention contains the urethane prepolymer (P) and may also contain elemental bismuth. The elemental bismuth may be contained as a catalyst during the production of the urethane prepolymer (P). From the viewpoints of the properties and reworkability of the pressure-sensitive adhesive curable composition (S), the content of elemental bismuth in the pressure-sensitive adhesive curable composition (S) is preferably 10 to 1,000 ppm, more preferably 50 to 500 ppm, per 100 parts by mass of the pressure-sensitive adhesive curable composition (S).

[0086] In the present invention, the content of bismuth element can be confirmed by atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry (ICP-AES), or inductively coupled plasma mass spectrometry (ICP-MS).

[0087] The pressure-sensitive adhesive curable composition (S) of the present invention may contain, in addition to the above-mentioned urethane prepolymer (P), crosslinking agent (C), compound (D) having a (meth)acryloyl group other than the urethane prepolymer (P), photopolymerization initiator (E), compound (F) having an active methylene group, and bismuth compound having elemental bismuth, by-products produced in the production of each constituent monomer, by-products produced in the production of the urethane prepolymer (P), solvents, antioxidants, ultraviolet absorbers, plasticizers, tackifiers, fillers, pigments, antistatic agents, and antigelling agents (urethanization retarders).

[0088] Examples of the solvent include the same solvents as those exemplified for the urethane prepolymer (P).

[0089] 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 of two or more. 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 pressure-sensitive adhesive curable composition (S), from the viewpoint of the antioxidant effect and adhesive strength of the cured product.

[0090] Examples of ultraviolet 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'-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxy-5-sulfobenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2,4-dihydroxy ... -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, bis(2-methoxy-4-hydroxy-5-benzoylphenyl)methane, etc.], benzotriazole compounds {2-(2'-hydroxy-5'- 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-3' ,5'-di-t-amylphenyl)benzotriazole, 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.}, and cyanoacrylate compounds (2-ethylhexyl-2-cyano-3,3'-diphenylacrylate, ethyl-2-cyano-3,3'-diphenylacrylate, etc.).The amount of the ultraviolet absorber used is preferably 5 parts by mass or less, more preferably 0.1 to 1 part by mass, per 100 parts by mass of the pressure-sensitive adhesive curable composition (S), from the viewpoint of the ultraviolet absorption effect and adhesive strength of the cured product.

[0091] Examples of the plasticizer include hydrocarbons [process oil, liquid polybutadiene, liquid polyisobutylene, liquid polyisoprene, liquid paraffin, chlorinated paraffin, paraffin wax, copolymer of ethylene and α-olefin (having 3 to 20 carbon atoms) (weight ratio 99.9 / 0.1 to 0.1 / 99.9) oligomer (Mw 5,000 to 100,000), copolymer of propylene and two kinds of α-olefin (having 4 to 20 carbon atoms) excluding ethylene (polymerized oligomers (Mw 5,000 to 100,000) in a ratio of 99.9 / 0.1 to 0.1 / 99.9; chlorinated paraffins; esters (phthalates [diethyl phthalate (DEP), dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DOP), didecyl phthalate, dilauryl phthalate, distearyl phthalate, diisononyl phthalate, etc.], adipates [di(2-ethylhexyl) adipate (DOA), dioctyl adipate, etc.] and sebacic acid esters (dioctyl sebacate, etc.); animal and vegetable oils and fats (linoleic acid, linolenic acid, etc.); and hydrogenated products of those having a hydrogenatable unsaturated double bond among these; fatty acid esters (butyl stearate, 2-ethylhexyl palmitate, 2-ethylhexyl stearate, behenic acid monoglyceride, cetyl 2-ethylhexanoate, isopropyl palmitate, cholesteryl isostearate, coconut fatty acid methyl ester, 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). One type of plasticizer may be used alone, or two or more types may be used in combination. 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, relative to 100 parts by mass of the curable composition for pressure-sensitive adhesives (S), from the viewpoint of the cohesive strength of the curable composition for pressure-sensitive adhesives (S).

[0092] Examples of tackifiers include terpene resins, terpene phenolic resins, phenolic 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 versions of those having hydrogenatable unsaturated double bonds. Tackifiers may be used alone or in combination. Of these, polar tackifiers are preferred from the viewpoint of adhesive strength, with rosin resins, phenolic resins, terpene phenolic resins, xylene resins, and hydrogenated versions thereof being more preferred, and terpene phenolic resins and hydrogenated versions thereof 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 curable composition (S), from the viewpoint of adhesive strength and heat resistance of the cured product.

[0093] Examples of fillers include carbonates (magnesium carbonate, calcium carbonate, etc.), sulfates (aluminum sulfate, calcium sulfate, barium sulfate, etc.), sulfites (calcium sulfite, etc.), molybdenum disulfide, silicates (aluminum silicate, calcium silicate, etc.), 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 one type may be used alone, or two or more types may be used in combination. 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 pressure-sensitive adhesive curable composition (S), from the viewpoint of the cohesive strength of the pressure-sensitive adhesive curable composition (S).

[0094] Examples of pigments include inorganic pigments (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, cobalt purple, etc.), and organic pigments (shellac, insoluble azo pigments, soluble azo pigments, condensed azo pigments, phthalocyanine blue, dye lake, etc.). The pigments 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 types. The amount of the pigment used is preferably 250 parts by mass or less, more preferably 0.1 to 50 parts by mass, per 100 parts by mass of the curable composition for pressure-sensitive adhesives (S), from the viewpoint of the cohesive strength of the curable composition for pressure-sensitive adhesives (S).

[0095] Examples of the antistatic agent include polyether polyol, surfactant, metallic conductive filler, carbon black, and quaternary ammonium salts with Mw of less than 5,000.

[0096] <Adhesive (U)> The adhesive (U) of the present invention contains a cured product of the adhesive curable composition (S). The cured product is obtained by irradiation with heat and / or active energy rays, and the adhesive (U) may be the cured product of the adhesive curable composition (S) as is, or an additive may be added to the cured product of the adhesive curable composition (S). Examples of the additive include the same additives as those exemplified for the adhesive curable composition (S).

[0097] The cured product of the pressure-sensitive adhesive curable composition (S) of the present invention exhibits adhesiveness by thermally curing the pressure-sensitive adhesive curable composition (S), and the adhesiveness decreases by irradiating the cured product with active energy rays. Therefore, the cured product is characterized by exhibiting good adhesiveness after thermal curing, and the adhesiveness decreases by irradiation with active energy rays, thereby exhibiting reworkability. From the viewpoint of adhesive strength and good reworkability, the cured product of the pressure-sensitive adhesive curable composition (S) of the present invention is preferably cured by irradiating the pressure-sensitive adhesive curable composition (S) with active energy rays after thermal curing.

[0098] From the viewpoints of handleability and curability, the content of the cured product of the pressure-sensitive adhesive curable composition (S) in the pressure-sensitive adhesive (U) is preferably 20 to 100 parts by mass, and more preferably 30 to 100 parts by mass, per 100 parts by mass of the pressure-sensitive adhesive (U).

[0099] The step of thermally curing the pressure-sensitive adhesive curable composition (S) can be achieved by heat treatment at preferably 90 to 170°C, more preferably 100 to 150°C, for preferably 0.5 to 10 minutes, more preferably 1 to 5 minutes, from the viewpoint of curability.

[0100] The step of irradiating the pressure-sensitive adhesive curable composition (S) with active energy rays can be carried out by irradiating with active energy rays such as electron beams, ultraviolet rays, visible light, and radiation. The photopolymerization initiator (E) is decomposed to polymerize the radical polymerization initiation site of the urethane prepolymer (P), thereby obtaining a cured product.

[0101] The active energy rays are preferably light having a wavelength of 250 to 450 nm, and more preferably light having a wavelength of 350 to 410 nm from the viewpoint of rapid curing.

[0102] Examples of light sources for the light irradiation include low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, ultraviolet electrodeless lamps, LED lamps, xenon arc lamps, carbon arc lamps, sunlight, solid-state lasers such as YAG lasers, semiconductor lasers, and gas lasers such as argon lasers. When using visible to infrared light, which is poorly absorbed by the photopolymerization initiator (E), curing can be carried out by using a sensitizer that absorbs that light.

[0103] The exposure dose of the active energy rays can be appropriately set depending on the wavelength and intensity of the active energy rays and the composition of the pressure-sensitive adhesive curable composition (S). For example, the exposure dose in the UV-A region is 10 to 6,000 mJ / cm. ２ It is preferable that the intensity is 100 to 4,000 mJ / cm ２ It is more preferable that:

[0104] <Adhesive Sheet (T)> The use of the adhesive (U) containing the cured product of the adhesive curable composition (S) of the present invention is not particularly limited, and an adhesive sheet (T) can be produced by disposing a layer of the adhesive (U) on one side of a resin film. The adhesive sheet (T) can be obtained by applying the adhesive curable composition (S) to one side of a resin film such as a polyester film or a polyolefin film and curing it with heat or the like. The adhesive sheet (T) can be used as a surface protection film to be attached to an optical component, etc.

[0105] Optical components to which the pressure-sensitive adhesive (U) and pressure-sensitive adhesive sheet (T) of the present invention are applied include polarizing plates, retardation plates, light diffusion plates, anti-reflection films, electromagnetic wave shielding films, and glass substrates used in liquid crystal displays, organic EL displays, plasma displays, field emission displays, etc.

[0106] Specific examples of methods for forming the pressure-sensitive adhesive sheet (T) include the following methods. A gravure coater, reverse roll coater, comma coater, spin coater, curtain coater, slot coater, bar coater, die coater, knife coater, or the like can be used to coat the substrate film with the pressure-sensitive adhesive (U). The coating amount (solid content) of the pressure-sensitive adhesive (U) during coating 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.

[0107] The coating temperature of the adhesive (U) when applied to the substrate film is preferably 10 to 160°C, more preferably 25 to 120°C, from the viewpoints of coatability and suppression of thermal degradation. The viscosity of the adhesive (U) at the coating temperature is preferably 0.01 to 100 Pa·s, more preferably 0.02 to 50 Pa·s, particularly preferably 0.03 to 10 Pa·s, from the viewpoints of formability (ability to apply thick coating and absence of poor appearance such as warping and sink marks after curing) and coatability. A general dry laminator or extrusion laminator is used for lamination. After lamination, the adhesive (U) is completely cured by aging at 10 to 50°C for 20 to 150 hours.

[0108] The present specification describes the following inventions. Invention (1) is a curable pressure-sensitive adhesive composition containing a urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group, a crosslinking agent (C), a compound (D) other than the urethane prepolymer (P) having a (meth)acryloyl group, a photopolymerization initiator (E), and a compound (F) having an active methylene group, in which the urethane prepolymer (P) is a urethane prepolymer obtained by reacting a hydroxyl group-containing component (A) containing a hydroxy(meth)acrylate (a1) with a polyisocyanate component (B). Invention (2) is a curable pressure-sensitive adhesive composition (S) according to invention (1), in which the content of the hydroxy(meth)acrylate (a1) in the hydroxyl group-containing component (A) is 0.2 to 10 wt % based on the total weight of the hydroxyl group-containing component (A). The present invention (3) is the pressure-sensitive adhesive curable composition (S) according to the present invention (1) or (2), wherein the average number of hydroxyl groups per molecule of the hydroxy(meth)acrylate (a1) in the hydroxyl group-containing component (A) is 1.1 to 2.0. The present invention (4) is the pressure-sensitive adhesive curable composition (S) according to any one of the present inventions (1) to (3), wherein the urethane prepolymer (P) has a hydroxyl value of 5 to 20 mgKOH / g. The present invention (5) is the pressure-sensitive adhesive curable composition (S) according to any one of the present inventions (1) to (4), wherein the urethane prepolymer (P) has a weight-average molecular weight (Mw) of 50,000 to 300,000. The present invention (6) is the pressure-sensitive adhesive curable composition (S) according to any one of the present inventions (1) to (5), which contains elemental bismuth. The present invention (7) is a pressure-sensitive adhesive (U) containing a cured product of the pressure-sensitive adhesive curable composition (S) according to any one of the present inventions (1) to (6). The present invention (8) is a pressure-sensitive adhesive sheet (T) having a resin film and a layer of the pressure-sensitive adhesive (U) according to the present invention (7) disposed on one side of the resin film.

[0109] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following, "parts" means "parts by mass."

[0110] [Production of hydroxyl group-containing urethane prepolymer (P)] <Production Example 1> 0.2 parts of hydroxy(meth)acrylate (a1-1), 19.8 parts of polyether polyol (a2-1), 48 parts of polyether polyol (a2-4), 32 parts of polyester polyol (a3-1), and 0.001 parts of hydroquinone as a polymerization inhibitor were added to a four-neck flask equipped with a stirring rod and a thermometer, and the mixture was stirred under reduced pressure at 80°C to dehydrate. After cooling to 70°C, 70 parts of ethyl acetate as a solvent and 5 parts of polyisocyanate component (B-1) were added in that order. The mixture was stirred to homogenize, and 0.05 parts of a bismuth compound was added as a catalyst. The mixture was heated to 76°C and reacted for 6 hours to obtain a mixture containing hydroxyl group-containing urethane prepolymer (P-1) and elemental bismuth. The hydroxyl value of the urethane prepolymer (P-1) was 10.6 mgKOH / g and the weight average molecular weight (Mw) was 120,000.

[0111] <Production Example 2> 2 parts of hydroxy(meth)acrylate (a1-1), 18 parts of polyether polyol (a2-1), 48 parts of polyether polyol (a2-4), 32 parts of polyester polyol (a3-1), and 0.002 parts of hydroquinone as a polymerization inhibitor were added to a four-neck flask equipped with a stirring rod and a thermometer, and the mixture was stirred under reduced pressure at 80 ° C. to dehydrate. After cooling to 70 ° C., 71 parts of ethyl acetate as a solvent and 7 parts of polyisocyanate component (B-1) were added in that order. The mixture was stirred to homogenize, and 0.06 parts of a bismuth compound was added as a catalyst. The mixture was heated to 76 ° C. and reacted for 6 hours to obtain a mixture containing a hydroxyl-containing urethane prepolymer (P-2) and elemental bismuth. The hydroxyl value of the urethane prepolymer (P-2) was 10.2 mg KOH / g and the weight average molecular weight (Mw) was 90,000.

[0112] <Production Example 3> 4 parts of hydroxy(meth)acrylate (a1-1), 16 parts of polyether polyol (a2-1), 48 parts of polyether polyol (a2-4), 32 parts of polyester polyol (a3-1), and 0.004 parts of hydroquinone as a polymerization inhibitor were added to a four-neck flask equipped with a stirring rod and a thermometer, and the mixture was stirred under reduced pressure at 80 ° C. to dehydrate. After cooling to 70 ° C., 73 parts of ethyl acetate as a solvent and 9 parts of polyisocyanate component (B-1) were added in that order. The mixture was stirred to homogenize, and 0.07 parts of a bismuth compound was added as a catalyst. The mixture was heated to 76 ° C. and reacted for 6 hours to obtain a mixture containing a hydroxyl-containing urethane prepolymer (P-3) and elemental bismuth. The hydroxyl value of the urethane prepolymer (P-3) was 9.4 mg KOH / g and the weight average molecular weight (Mw) was 100,000.

[0113] <Production Example 4> 6 ​​parts of hydroxy(meth)acrylate (a1-1), 14 parts of polyether polyol (a2-1), 48 parts of polyether polyol (a2-4), 32 parts of polyester polyol (a3-1), and 0.006 parts of hydroquinone as a polymerization inhibitor were added to a four-neck flask equipped with a stirring rod and a thermometer, and the mixture was stirred at 80°C under reduced pressure to dehydrate. After cooling to 70°C, 74 parts of ethyl acetate as a solvent and 11 parts of polyisocyanate component (B-1) were added in that order. The mixture was stirred to homogenize, and 0.08 parts of a bismuth compound was added as a catalyst. The mixture was heated to 76°C and reacted for 6 hours to obtain a mixture containing a hydroxyl-containing urethane prepolymer (P-4) and elemental bismuth. The hydroxyl value of the urethane prepolymer (P-4) was 9.1 mgKOH / g and the weight-average molecular weight (Mw) was 120,000.

[0114] <Production Example 5> 10 parts of hydroxy(meth)acrylate (a1-1), 10 parts of polyether polyol (a2-1), 48 parts of polyether polyol (a2-4), 32 parts of polyester polyol (a3-1), and 0.01 parts of hydroquinone as a polymerization inhibitor were added to a four-neck flask equipped with a stirring rod and a thermometer, and the mixture was stirred under reduced pressure at 80 ° C. to dehydrate. After cooling to 70 ° C., 77 parts of ethyl acetate as a solvent and 16 parts of polyisocyanate component (B-1) were added in that order. The mixture was stirred to homogenize, and 0.1 parts of a bismuth compound was added as a catalyst. The mixture was heated to 76 ° C. and reacted for 6 hours to obtain a mixture containing a hydroxyl-containing urethane prepolymer (P-5) and elemental bismuth. The hydroxyl value of the urethane prepolymer (P-5) was 10.8 mg KOH / g and the weight average molecular weight (Mw) was 110,000.

[0115] <Production Example 6> 5 parts of hydroxy(meth)acrylate (a1-1), 5 parts of hydroxy(meth)acrylate (a1-2), 10 parts of polyether polyol (a2-1), 48 parts of polyether polyol (a2-4), 32 parts of polyester polyol (a3-1), and 0.01 parts of hydroquinone as a polymerization inhibitor were added to a four-neck flask equipped with a stirring rod and a thermometer, and the mixture was stirred at 80°C under reduced pressure to dehydrate. After cooling to 70°C, 75 parts of ethyl acetate as a solvent and 13 parts of polyisocyanate component (B-1) were added in that order. The mixture was stirred to homogenize, and 0.07 parts of a bismuth compound was added as a catalyst. The mixture was heated to 76°C and reacted for 6 hours to obtain a mixture containing a hydroxyl-containing urethane prepolymer (P-6) and elemental bismuth. The hydroxyl value of the urethane prepolymer (P-6) was 8.2 mgKOH / g and the weight average molecular weight (Mw) was 80,000.

[0116] <Production Example 7> 1 part of hydroxy(meth)acrylate (a1-1), 9 parts of hydroxy(meth)acrylate (a1-2), 10 parts of polyether polyol (a2-1), 48 parts of polyether polyol (a2-4), 32 parts of polyester polyol (a3-1), and 0.01 parts of hydroquinone as a polymerization inhibitor were added to a four-neck flask equipped with a stirring rod and a thermometer, and the mixture was stirred under reduced pressure at 80 ° C. to dehydrate. After cooling to 70 ° C., 75 parts of ethyl acetate as a solvent and 12 parts of polyisocyanate component (B-1) were added in that order. The mixture was stirred to homogenize, and 0.1 parts of a bismuth compound was added as a catalyst. The temperature was raised to 76 ° C. and the mixture was allowed to react for 6 hours, yielding a mixture containing a urethane prepolymer (P-7) having hydroxyl groups and elemental bismuth. The hydroxyl value of the urethane prepolymer (P-7) was 8.1 mg KOH / g and the weight average molecular weight (Mw) was 100,000.

[0117] <Production Example 8> 4 parts of hydroxy(meth)acrylate (a1-1), 64 parts of polyether polyol (a2-3), 32 parts of polyether polyol (a2-4), and 0.004 parts of hydroquinone as a polymerization inhibitor were added to a four-neck flask equipped with a stirring rod and a thermometer, and the mixture was stirred at 80°C under reduced pressure to dehydrate. After cooling to 70°C, 73 parts of ethyl acetate as a solvent and 10 parts of polyisocyanate component (B-1) were added in that order. The mixture was stirred to homogenize, and 0.1 parts of a bismuth compound was added as a catalyst. The temperature was raised to 76°C and the mixture was allowed to react for 6 hours, yielding a mixture containing a urethane prepolymer (P-8) having hydroxyl groups and elemental bismuth. The hydroxyl value of the urethane prepolymer (P-8) was 5.3 mgKOH / g and the weight average molecular weight (Mw) was 150,000.

[0118] <Production Example 9> 4 parts of hydroxy(meth)acrylate (a1-1), 28 parts of polyether polyol (a2-1), 32 parts of polyether polyol (a2-4), 36 parts of polyester polyol (a3-1), and 0.004 parts of hydroquinone as a polymerization inhibitor were added to a four-neck flask equipped with a stirring rod and a thermometer, and the mixture was stirred under reduced pressure at 80 ° C. to dehydrate. After cooling to 70 ° C., 73 parts of ethyl acetate as a solvent and 9 parts of polyisocyanate component (B-1) were added in that order. The mixture was stirred to homogenize, and 0.07 parts of a bismuth compound was added as a catalyst. The mixture was heated to 76 ° C. and reacted for 6 hours to obtain a mixture containing a urethane prepolymer (P-9) having hydroxyl groups and elemental bismuth. The hydroxyl value of the urethane prepolymer (P-9) was 10.8 mg KOH / g, and the weight average molecular weight (Mw) was 130,000.

[0119] <Production Example 10> 1 part of hydroxy(meth)acrylate (a1-1), 49 parts of polyether polyol (a2-2), 50 parts of polyether polyol (a2-3), and 0.001 parts of hydroquinone as a polymerization inhibitor were added to a four-neck flask equipped with a stirring rod and a thermometer, and the mixture was stirred at 80°C under reduced pressure to dehydrate. After cooling to 70°C, 31 parts of ethyl acetate as a solvent and 23 parts of polyisocyanate component (B-2) were added in that order. The mixture was stirred to homogenize, and 0.02 parts of a bismuth compound as a catalyst was added. The mixture was heated to 76°C and reacted for 2 hours to obtain a solution containing a urethane prepolymer having isocyanate groups. After cooling to 70°C, 240 parts of ethyl acetate was added and stirred to homogenize. Next, 2.35 parts of the hydroxyl-containing amine (a7-1) and 0.15 parts of the hydroxyl-containing amine (a7-2) were stirred with 26.0 parts of tetrahydrofuran to prepare a homogeneous amine solution, and the entire amount was added dropwise over 5 minutes at 25°C, and the reaction was continued for another hour, yielding a mixture containing a hydroxyl-containing urethane prepolymer (P-10) and elemental bismuth. The hydroxyl value of the urethane prepolymer (P-10) was 11.0 mgKOH / g, and the weight-average molecular weight (Mw) was 230,000.

[0120] <Production Example 11> 2 parts of hydroxy(meth)acrylate (a1-1), 98 parts of polyether polyol (a2-3), and 0.002 parts of hydroquinone as a polymerization inhibitor were added to a four-neck flask equipped with a stirring rod and a thermometer, and the mixture was stirred at 80°C under reduced pressure to dehydrate. After cooling to 70°C, 30 parts of ethyl acetate as a solvent and 19 parts of polyisocyanate component (B-2) were added in that order. The mixture was stirred to homogenize, and 0.02 parts of a bismuth compound was added as a catalyst. The mixture was heated to 76°C and reacted for 2 hours to obtain a solution containing a urethane prepolymer having isocyanate groups. After cooling to 70°C, 227 parts of ethyl acetate was added and stirred to homogenize. Next, 2.12 parts of the hydroxyl-containing amine (a7-1) and 0.15 parts of the hydroxyl-containing amine (a7-2) were stirred with 24.7 parts of tetrahydrofuran to prepare a homogeneous amine solution, and the entire amount was added dropwise over 5 minutes at 25°C, and the reaction was continued for another hour, yielding a mixture containing a hydroxyl-containing urethane prepolymer (P-11) and elemental bismuth. The hydroxyl value of the urethane prepolymer (P-11) was 10.3 mgKOH / g, and the weight-average molecular weight (Mw) was 190,000.

[0121] <Production Example 12> 10 parts of hydroxy(meth)acrylate (a1-1), 90 parts of polyether polyol (a2-3), and 0.01 parts of hydroquinone as a polymerization inhibitor were added to a four-neck flask equipped with a stirring rod and a thermometer, and the mixture was stirred at 80°C under reduced pressure to dehydrate. After cooling to 70°C, 32 parts of ethyl acetate as a solvent and 29 parts of polyisocyanate component (B-2) were added in that order. The mixture was stirred to homogenize, and 0.02 parts of a bismuth compound was added as a catalyst. The mixture was heated to 76°C and reacted for 2 hours to obtain a solution containing a urethane prepolymer having isocyanate groups. After cooling to 70°C, 280 parts of ethyl acetate was added and stirred to homogenize. Next, 1.61 parts of the hydroxyl-containing amine (a7-1) and 0.13 parts of the hydroxyl-containing amine (a7-2) were stirred with 26.3 parts of tetrahydrofuran to prepare a homogeneous amine solution, and the entire amount was added dropwise over 5 minutes at 25°C, and the reaction was continued for another hour, yielding a mixture containing a hydroxyl-containing urethane prepolymer (P-12) and elemental bismuth. The hydroxyl value of the urethane prepolymer (P-12) was 9.4 mgKOH / g, and the weight-average molecular weight (Mw) was 180,000.

[0122] Comparative Production Example 1: 20 parts of polyether polyol (a2-1), 48 parts of polyether polyol (a2-4), and 32 parts of polyester polyol (a3-1) were placed in a four-neck flask equipped with a stirring rod and a thermometer, and the mixture was stirred under reduced pressure at 100°C to dehydrate. After cooling to 70°C, 70 parts of ethyl acetate as a solvent and 4.6 parts of polyisocyanate component (B-1) were added in that order. The mixture was stirred to homogenize, and 0.02 parts of a bismuth compound was added as a catalyst. The mixture was heated to 76°C and reacted for 6 hours to obtain a mixture containing a hydroxyl-containing urethane prepolymer (P'-1) and elemental bismuth. The hydroxyl value of the urethane prepolymer (P'-1) was 10.3 mgKOH / g and the weight-average molecular weight (Mw) was 120,000.

[0123] Table 1 shows a list of the raw materials and their amounts used in Production Examples 1 to 12 and Comparative Production Example 1, as well as the properties of the resulting urethane prepolymers.

[0124]

[0125] In Table 1, the components are as follows: Hydroxy(meth)acrylate (a1-1): glycerin monomethacrylate [NOF Corporation's "Blenmar GLM (registered trademark)": the average number of hydroxyl groups per molecule is 2.0] Hydroxy(meth)acrylate (a1-2): hydroxyethyl acrylate [Nippon Shokubai Co., Ltd.'s "2-hydroxyethyl acrylate": the average number of hydroxyl groups per molecule is 1.0] Polyether polyol (a2-1): polytetramethylene ether glycol [Mitsubishi Chemical Corporation's "PTMG3000"] Polyether polyol (a2-2): polyoxypropylene glycol [Sanyo Chemical Industries, Ltd.'s "Sanyx PP-1000 (registered trademark)"] Polyether polyol (a2-3): polyoxypropylene glycol [Sanyo Chemical Industries, Ltd.'s "Sanyx PP-2000 (registered trademark)"] Polyether polyol (a2-4): Polyoxypropylene triol [Sanyo Chemical Industries, Ltd., "Sannyx GA-5000 (registered trademark)"] Polyester polyol (a3-1): Polycondensate of 3-methyl-1,5-pentanediol and adipic acid [Kuraray Co., Ltd., "Kuraray Polyol P-2010"] Hydroxyl group-containing amine (a7-1): 2-(2-aminoethylamino)ethanol Hydroxyl group-containing amine (a7-2): 1-amino-2-propanol Polyisocyanate component (B-1): Hexamethylene diisocyanate [Asahi Kasei Corporation, "Duranate 50M (registered trademark)"] Polyisocyanate component (B-2): Isophorone diisocyanate [Sumika Covestro Urethane Co., Ltd., "Desmodur I (registered trademark)"] Catalyst: Bismuth octylate ["Neostan U-600 (registered trademark)" manufactured by Nitto Kasei Co., Ltd.: bismuth element content is 18.5%]

[0126] [Production of Pressure-Sensitive Adhesive Sheet (T)] <Examples 1 to 15 and Comparative Examples 1 to 4> A mixture containing a urethane prepolymer having a hydroxyl group {(P-1) to (P-12) or (P'-1)} and elemental bismuth, a crosslinking agent {(C-1) or (C-2)}, a compound having a (meth)acryloyl group other than (P) {(D-1) or (D-2)}, a photopolymerization initiator (E-1), a compound having an active methylene group (F-1) as a catalyst, and a solvent were blended in the amounts shown in Tables 2 and 3, and the mixture was centrifuged and degassed to obtain pressure-sensitive adhesive curable compositions {(S-1) to (S-15) and (S'-1) to (S'-4)}. The pressure-sensitive adhesive curable composition (S-1) was applied to a 50 μm thick highly adhesive polyester film using an applicator so that the film thickness after drying would be 50 μm. After drying the film at 120 ° C. for 3 minutes, a release film [Nippa Corporation's "PET25x2-CBD-A3"] was attached to the surface coated with the pressure-sensitive adhesive curable composition (S-1), and the surface was aged at 50 ° C. for 3 days to obtain a pressure-sensitive adhesive sheet (T-1). Pressure-sensitive adhesive sheets (T-2) to (T-15) and (T'-1) to (T'-4) were obtained in the same manner as for the pressure-sensitive adhesive sheet (T-1). The results of evaluation of the obtained pressure-sensitive adhesive sheets (T-1) to (T-15) and (T'-1) to (T'-4) by the following methods are shown in Tables 2 and 3.

[0127]

[0128]

[0129] In Tables 2 and 3, the components are as follows: Crosslinking agent (C-1): HDI-based isocyanurate polyisocyanate [Duranate TKA-100 (registered trademark) manufactured by Asahi Kasei Corporation] Crosslinking agent (C-2): HDI-based biuret polyisocyanate [Duranate 24A-100 (registered trademark) manufactured by Asahi Kasei Corporation] Compound (D-1) having a (meth)acryloyl group other than urethane prepolymer (P): dipentaerythritol hexaacrylate [Neomer DA-600 (registered trademark) manufactured by Sanyo Chemical Industries, Ltd.] Compound (D-2) having a (meth)acryloyl group other than urethane prepolymer (P): glycerin monomethacrylate [Blenmer GLM (registered trademark) manufactured by NOF Corporation] Photopolymerization initiator (E-1): 1-hydroxycyclohexyl phenyl ketone [IGM Resins B.V. "Omnirad 184" manufactured by Fujifilm Corporation] Compound having an active methylene group (F-1): acetylacetone [manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.] Catalyst: dibutyltin dibutyl laurate [manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.]

[0130] [Evaluation of Pressure-Sensitive Adhesive Sheets (T)] (Method for Evaluating Adhesive Strength After Heat Curing) Each pressure-sensitive adhesive sheet (T) was cut into a size of 100 mm x 25 mm, the release film was peeled off, and the sheet was pressed onto a glass plate using a 2 kg roller to obtain a laminate. The laminate was then left to stand in an atmosphere at 23°C for 30 minutes, and the 180° peel strength (adhesive strength) was measured using a tensile tester at 23°C and a pulling rate of 300 mm / min. Measurements were performed on three samples, and the average value was used for evaluation. Furthermore, the state of failure during the adhesive strength measurement was evaluated based on the following criteria. Since adhesives are required to have good adhesive properties after heat curing, it is preferable that the adhesive has an adhesive strength of 1 N / 25 mm or more and does not experience cohesive failure from the perspective of adhesive residue. <Evaluation Criteria for the State of Failure> ○ (Excellent): No cohesive failure occurred in all three samples. Δ (Good): Cohesive failure occurred in one or two samples, and no cohesive failure occurred in the remaining sample. × (Poor): Cohesive failure occurred in all three samples.

[0131] (Method for evaluating adhesive strength after standing at 50°C for 30 days) Each pressure-sensitive adhesive sheet (T) was cut into a size of 100 mm x 25 mm, the release film was peeled off, and the sheet was pressed onto a glass plate using a 2 kg roller to obtain a laminate. The laminate was then left standing at 50°C for 30 days and then left standing in an atmosphere at 23°C for 30 minutes. Thereafter, the 180° peel strength (adhesive strength) was measured using a tensile tester at 23°C and a pulling rate of 300 mm / min. Measurements were performed on three samples, and the average value was used for evaluation. The state of failure during adhesive strength measurement was evaluated from the following perspectives. For the same reasons as after heat curing, the adhesive after standing at 50°C for 30 days preferably has an adhesive strength of 1 N / 25 mm or more, and from the viewpoint of adhesive residue, it is preferable that cohesive failure does not occur. In addition, since it is required to maintain adhesive strength after heat curing, the value obtained by dividing the adhesive strength after standing at 50°C for 30 days by the adhesive strength after heat curing is preferably 0.5 to 1.2. <Evaluation criteria for failure state> ○ (Excellent): No cohesive failure occurred in any of the three samples. △ (Good): Cohesive failure occurred in one or two samples, and no cohesive failure occurred in the remaining sample. × (Poor): Cohesive failure occurred in all three samples.

[0132] (Method for evaluating adhesive strength after UV irradiation) Each pressure-sensitive adhesive sheet (T) was cut into a size of 100 mm x 25 mm, the release film was peeled off, and the sheet was pressed onto a glass plate using a 2 kg roller to obtain a laminate. After standing at 50°C for 30 days, the sheet was irradiated at 150 mW / cm from the highly adhesive polyester film side at 23°C using an ultraviolet irradiation device ["LC6B" manufactured by Heraeus] and an electrodeless ultraviolet lamp ["Light Hammer6 MKII" manufactured by Heraeus, equipped with an H bulb]. ２ , 2000mJ / cm ２The laminate was then left to stand for 30 minutes in an atmosphere at 23°C, and the 180° peel strength (adhesive strength) was measured using a tensile tester at 23°C and a pulling rate of 300 mm / min. Measurements were performed on three samples, and the average value was used for evaluation. The failure state during the adhesive strength measurement was evaluated based on the following criteria. Since the adhesive is required to have good reworkability after UV irradiation, it is preferable that the adhesive strength after UV irradiation divided by the adhesive strength after 30 days at 50°C be less than 0.1 and no cohesive failure occurs. It is even more preferable that the adhesive strength after UV irradiation divided by the adhesive strength after 30 days at 50°C be less than 0.05 and no cohesive failure occurs. <Failure State Evaluation Criteria> ○ (Excellent): No cohesive failure occurred in all three samples. Δ (Good): Cohesive failure occurred in one or two samples, and no cohesive failure occurred in the remaining sample. × (Poor): Cohesive failure occurred in all three samples.

[0133] As can be seen from Tables 2 and 3, in Examples 1 to 15, a pressure-sensitive adhesive curable composition (S) was used that contained a urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group, a crosslinking agent (C), a compound (D) other than the urethane prepolymer (P) having a (meth)acryloyl group, a photopolymerization initiator (E), and a compound (F) having an active methylene group, and therefore a pressure-sensitive adhesive sheet (T) was obtained that had excellent reworkability, left little adhesive residue on the adherend, and was able to maintain adhesive strength for a long period of time.

[0134] In Comparative Example 1, which did not use the compound (F) having an active methylene group, the adhesive strength after standing at 50°C for 30 days divided by the adhesive strength after heat curing was less than 0.5, and the adhesive sheet was unable to maintain its adhesive strength over a long period of time. In Comparative Example 2, in which the urethane prepolymer did not use hydroxy(meth)acrylate (a1), the adhesive sheet had low adhesive strength. In Comparative Example 3, in which the crosslinking agent (C) was not used, cohesive failure of the adhesive occurred after heat curing. In Comparative Example 4, in which the compound (D) having a (meth)acryloyl group other than the urethane prepolymer (P) was not used, the adhesive strength did not decrease after UV irradiation and reworkability was poor.

[0135] The pressure-sensitive adhesive using the curable composition for pressure-sensitive adhesives of the present invention and the pressure-sensitive adhesive sheet using the pressure-sensitive adhesive have excellent reworkability, leave little adhesive residue on the adherend, and can maintain adhesive strength for a long period of time. Therefore, they can be used in a wide range of applications, such as optical components, automotive components, building materials, and medical applications, and are extremely useful.

Claims

1. A curable composition for adhesives (S) comprising a urethane prepolymer (P) having a hydroxyl group and a (meth)acryloyl group, a crosslinking agent (C), a compound (D) having a (meth)acryloyl group other than the urethane prepolymer (P), a photopolymerization initiator (E), and a compound (F) having an active methylene group, wherein the urethane prepolymer (P) is a urethane prepolymer obtained by reacting a hydroxyl group-containing component (A) including a hydroxy(meth)acrylate (a1) with a polyisocyanate component (B).

2. The pressure-sensitive adhesive curable composition (S) according to claim 1, wherein the content of the hydroxy(meth)acrylate (a1) in the hydroxyl group-containing component (A) is 0.2 to 10 wt % based on the total weight of the hydroxyl group-containing component (A).

3. The pressure-sensitive adhesive curable composition (S) according to claim 1, wherein the average number of hydroxyl groups per molecule of the hydroxy(meth)acrylate (a1) in the hydroxyl group-containing component (A) is 1.1 to 2.

0.

4. The pressure-sensitive adhesive curable composition (S) according to claim 1, wherein the hydroxyl value of the urethane prepolymer (P) is 5 to 20 mgKOH / g.

5. The pressure-sensitive adhesive curable composition (S) according to claim 1, wherein the weight-average molecular weight (Mw) of the urethane prepolymer (P) is 50,000 to 300,000.

6. The pressure-sensitive adhesive curable composition (S) according to claim 1, which contains bismuth element.

7. An adhesive (U) containing a cured product of the adhesive curable composition (S) according to claim 1.

8. An adhesive sheet (T) having a resin film and a layer of the adhesive (U) according to claim 7, disposed on one side of the resin film.

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