Active energy ray-curable peelable adhesive composition and adhesive sheet

Abstract

Provided is an active energy ray-curable peelable adhesive composition which has good adhesive force before irradiation with active energy rays, has reduced adhesive force after irradiation with active energy rays even when exposed to high temperatures, does not have adhesive residues, and has excellent peelability. An active energy ray-curable peelable adhesive composition containing an acrylic resin (A) and a nitroso compound (B), the content of the nitroso compound (B) being 0.01-1 parts by mass per 100 parts by mass of the acrylic resin (A).

Description

Technical Field

[0001] The present invention relates to an active energy ray-curable release-type adhesive composition and an adhesive sheet, and more particularly to an adhesive composition used in an adhesive for a release-type adhesive sheet for temporary surface protection during processing of workpieces such as semiconductor wafers, printed circuit boards, glass processed products, metal plates, and plastic plates. In particular, the present invention relates to an active energy ray-curable release-type adhesive composition and an adhesive sheet. Background Art

[0002] Conventionally, in processing steps such as fabricating integrated circuits and making openings using semiconductor wafers, a surface protection adhesive sheet is used for the purpose of preventing contamination and damage of the workpiece to temporarily protect the surface of the workpiece. In recent years, due to reasons such as miniaturization of processing technology and thinning of workpieces, an appropriate adhesive force for the workpiece is required. On the other hand, after the surface protection function is completed, the surface protection adhesive sheet needs to be peeled off, and it is required to be peeled off with a small force without residual adhesive. In addition, in recent years, the surface protection adhesive sheet is used not only for semiconductor wafers but also in the processing of various components.

[0003] As such an adhesive sheet, an active energy ray-curable adhesive composition that cures by irradiation with active energy rays and can reduce the adhesive force is effective. For example, it exhibits active energy ray curability by (1) blending a monomer and / or oligomer having an ethylenically unsaturated group and an acrylic resin, or (2) using an acrylic resin containing an ethylenically unsaturated group in the acrylic resin itself.

[0004] In recent years, in the manufacturing process of electronic components, there are few cases where components with an adhesive tape attached are exposed to high temperatures. Therefore, for adhesive tapes used in the manufacturing process of electronic components, heat resistance that can withstand high temperature conditions is also required. For example, Patent Document 1 discloses an adhesive sheet coated with an active energy ray-curable adhesive having a glass transition temperature of -50°C or higher and 10°C or lower, and it is described that even after heat treatment and after irradiation with active energy rays, the adhesive force between the wafer chip and the adhesive sheet is reduced, and the wafer chip can be easily picked up.

[0005] In addition, Patent Document 2 describes an adhesive that is excellent in re-peelability even after being exposed to high temperature and humid conditions by incorporating a phosphorus-based antioxidant into an acrylic resin.

[0006] Furthermore, Patent Document 3 describes an adhesive which, by incorporating a hindered phenol antioxidant into an energy ray-curable adhesive, exhibits excellent peelability even after being exposed to high temperature and humid conditions.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: International Publication No. 2020 / 100491

[0010] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2020-158691

[0011] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2019-145575 Summary of the Invention

[0012] Problems to be Solved by the Invention

[0013] However, in the disclosed technology of the aforementioned Patent Document 1, after heat treatment at 150°C, the adhesive force decreases upon irradiation with active energy rays, showing peelability. However, under higher temperature conditions, such as heat treatment conditions of 175 to 200°C, there is a problem that sufficient peelability cannot be obtained, and it is not yet satisfactory.

[0014] In addition, in the disclosed technologies of the aforementioned Patent Document 2 and Patent Document 3, there is also a problem that the adhesive force increases under higher temperature conditions and sufficient peelability cannot be obtained, and it is not yet satisfactory.

[0015] Therefore, in the present invention, in this background, there is provided an energy ray-curable peelable adhesive composition capable of obtaining an adhesive, which has good adhesive force before irradiation with active energy rays, can suppress an excessive increase and decrease in adhesive force even when exposed to high temperature, reduces contamination of the adherend, has reduced adhesive force after irradiation with active energy rays, has no residual adhesive, and has excellent peelability.

[0016] Solutions to the Problems

[0017] However, in view of this situation, the present inventors repeatedly conducted in-depth research and found that: by incorporating a specific amount of nitroso compound into an energy ray-curable peelable adhesive composition containing an acrylic resin, the following adhesive can be obtained, which has good adhesive force before irradiation with active energy rays, can suppress an excessive increase and decrease in adhesive force even when exposed to high temperature, reduces contamination of the adherend, has reduced adhesive force after irradiation with active energy rays, has no residual adhesive, and has excellent peelability.

[0018] That is, the present invention provides the following [1] to

[17] .

[0019] [1]A radiation curable release type adhesive composition containing an acrylic resin (A) and a nitroso compound (B), wherein the content of the nitroso compound (B) is 0.01 to 1 part by mass with respect to 100 parts by mass of the acrylic resin (A).

[0020] [2]The radiation curable release type adhesive composition according to [1], wherein the acrylic resin (A) has a structural unit derived from an alkyl (meth)acrylate (a1).

[0021] [3]The radiation curable release type adhesive composition according to [1] or [2], wherein the acrylic resin (A) has a structural unit derived from a functional group-containing monomer (a2).

[0022] [4]The radiation curable release type adhesive composition according to any one of [1] to [3], wherein the acrylic resin (A) has a structural unit derived from a hydroxyl group-containing monomer (a2-1).

[0023] [5]The radiation curable release type adhesive composition according to [4], wherein the content of the structural unit derived from the hydroxyl group-containing monomer (a2-1) is 0.1 to 10% by mass of all the structural units of the acrylic resin (A).

[0024] [6]The radiation curable release type adhesive composition according to any one of [1] to [5], wherein the acrylic resin (A) has a structural unit derived from a carboxyl group-containing monomer (a2-2).

[0025] [7]The radiation curable release type adhesive composition according to [6], wherein the content of the structural unit derived from the carboxyl group-containing monomer (a2-2) is 0.01 to 10% by mass of all the structural units of the acrylic resin (A).

[0026] [8]The radiation curable release type adhesive composition according to any one of [1] to [7], wherein the acrylic resin (A) is an acrylic resin (A1) having an ethylenically unsaturated group.

[0027] [9]The radiation curable release type adhesive composition according to [8], wherein the content of the ethylenically unsaturated group in the acrylic resin (A1) having an ethylenically unsaturated group is 5 to 250 mmol / 100 g.

[0028]

[10] The active energy ray-curable pressure-sensitive adhesive composition according to any one of [1] to [9] further contains a urethane (meth)acrylate compound (C).

[0029]

[11] The active energy ray-curable pressure-sensitive adhesive composition according to

[10] , wherein the urethane (meth)acrylate compound (C) has an ethylenically unsaturated group, and the number of the ethylenically unsaturated groups is 5 to 20.

[0030]

[12] The active energy ray-curable pressure-sensitive adhesive composition according to

[10] or

[11] , wherein the urethane (meth)acrylate compound (C) is a reaction product of a hydroxy group-containing (meth)acrylate compound and a polyisocyanate compound (b2), and the hydroxy group-containing (meth)acrylate compound has 3 or more ethylenically unsaturated groups in the molecule.

[0031]

[13] The active energy ray-curable pressure-sensitive adhesive composition according to any one of [1] to

[12] , wherein the nitroso compound (B) is an ammonium salt of N-nitrosophenylhydroxylamine and / or an aluminum salt of N-nitrosophenylhydroxylamine.

[0032]

[14] The active energy ray-curable pressure-sensitive adhesive composition according to any one of [1] to

[13] further contains a crosslinking agent (D).

[0033]

[15] The active energy ray-curable pressure-sensitive adhesive composition according to any one of [1] to

[14] further contains a photopolymerization initiator (E).

[0034]

[16] An adhesive sheet having an adhesive layer obtained by crosslinking the adhesive composition according to any one of [1] to

[15] .

[0035]

[17] The adhesive sheet according to

[16] , wherein the adhesive layer is cured by irradiation with active energy rays and can be peeled off.

[0036] Effects of the Invention

[0037] The active energy ray-curable pressure-sensitive adhesive composition of the present invention can be made into the following pressure-sensitive adhesive, which has good adhesiveness before irradiation with active energy rays, can suppress an excessive increase and decrease in adhesiveness even when exposed to high temperatures, reduces contamination of the adherend, and after irradiation with active energy rays, the adhesiveness is reduced, there is no residual adhesive, and it has excellent peelability. Detailed Description of the Invention

[0038] Hereinafter, the embodiments for carrying out the present invention will be specifically described, but the present invention is not limited thereto.

[0039] In the present invention, “(meth)acrylic” means acrylic or methacrylic, “(meth)acryloyl” means acryloyl or methacryloyl, and “(meth)acrylate” means acrylate or methacrylate.

[0040] It should be noted that in the present invention, “sheet” is not particularly distinguished from “film” and “tape”, and is described in a sense that includes them as well.

[0041] In the present invention, when expressed as “X to Y” (X and Y are arbitrary numbers), unless otherwise specified, it means “X or more and Y or less”.

[0042] In the present invention, “x and / or y (x and y are arbitrary components)” means at least one of x and y, and means any one of only x, only y, and x and y.

[0043] Hereinafter, when the present invention is described in detail, the copolymerization ratio of (meth)acrylate monomers and other compounds constituting the acrylic resin, etc., and the blending amount of other compounds may sometimes be denoted as “mass %” and “parts by mass”, which means a mass basis. For example, the mass % in the acrylic resin is the ratio when all copolymerization components are set to 100%.

[0044] The adhesive composition according to one embodiment of the present invention (hereinafter referred to as “the present adhesive composition”) is generally mainly used for the adhesive layer of an adhesive sheet on the premise of being peeled off after being pasted to a workpiece such as a metal plate, a plastic plate, or a semiconductor wafer. The aforementioned adhesive sheet is formed by coating the present adhesive composition on a substrate sheet to form an adhesive layer. After being pasted to the workpiece, by irradiating active energy rays, the adhesive layer is cured and the adhesive force is reduced, and it can be easily peeled off from the workpiece.

[0045] The present adhesive composition contains an acrylic resin (A) and a nitroso compound (B). Hereinafter, each component of the present adhesive composition will be described.

[0046] 〔Acrylic resin (A)〕

[0047] The aforementioned acrylic resin (A) is a resin obtained by polymerizing a polymerization component containing at least one (meth)acrylate monomer.

[0048] In addition, the aforementioned acrylic resin (A) may be an acrylic resin (A1) having an ethylenically unsaturated group described later.

[0049] The aforementioned acrylic resin (A) preferably has a structural unit derived from the (meth)acrylic acid alkyl ester (a1), a structural unit derived from the functional group-containing monomer (a2), and, if necessary, a structural unit derived from other copolymerizable monomers (a3).

[0050] This acrylic resin (A) is preferably obtained by copolymerizing a copolymerizable component containing the (meth)acrylic acid alkyl ester (a1), the functional group-containing monomer (a2), and other copolymerizable monomers (a3) as needed.

[0051] It should be noted that the content of each monomer relative to the entire copolymerizable component can be regarded as the content of the structural unit derived from that monomer in the acrylic resin (A) as a copolymer. For example, the content of the acrylic (meth)acrylate (a1) relative to the entire copolymerizable component can be regarded as the content of the structural unit derived from the acrylic (meth)acrylate (a1) in the acrylic resin (A).

[0052] [(meth)acrylic acid alkyl ester (a1)]

[0053] In the aforementioned (meth)acrylic acid alkyl ester (a1), the number of carbon atoms in the alkyl group is usually 1 to 20, preferably 1 to 12, and more preferably 1 to 8. If the number of carbon atoms is too large, there is a tendency for residual glue to easily form on the workpiece to be processed.

[0054] Examples of the aforementioned (meth)acrylic acid alkyl ester (a1) include (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-propyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, etc. (meth)acrylic acid aliphatic alkyl esters; (meth)acrylic acid cyclohexyl ester, isobornyl (meth)acrylate, etc. (meth)acrylic acid alicyclic alkyl esters. They can be used alone or in combination of two or more. Among the aforementioned (meth)acrylic acid alkyl esters (a1), from the viewpoints of copolymerizability, adhesive properties, ease of processing, and ease of obtaining raw materials, (meth)acrylic acid aliphatic alkyl esters are preferred, and methyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are more preferred.

[0055] The content of the structural unit derived from the (meth)acrylic acid alkyl ester (a1) in the aforementioned acrylic resin (A) is usually 30 to 99.9% by mass, preferably 40 to 99% by mass, and particularly preferably 50 to 97% by mass of all the structural units of the acrylic resin (A).

[0056] In addition, when the acrylic resin (A) is an acrylic resin (A1) having an ethylenically unsaturated group, the content of the structural unit derived from the (meth)acrylic acid alkyl ester (a1) is particularly preferably 50 to 80% by mass.

[0057] If the content is within the above range, there is a tendency for the adhesive strength before the active energy ray irradiation to be further improved. In addition, if the content is too small, there is a tendency for the adhesive strength before the active energy ray irradiation to be easily reduced, and if it is too large, there is a tendency for the adhesive strength after the active energy ray irradiation to become too high.

[0058] [Functional group-containing monomer (a2)]

[0059] The aforementioned functional group-containing monomer (a2) does not include the (meth)acrylic acid alkyl ester (a1), and examples thereof include a hydroxyl group-containing monomer (a2-1), a carboxyl group-containing monomer (a2-2), an amino group-containing monomer (a2-3), an amide group-containing monomer (a2-4), a glycidyl group-containing monomer, a sulfonic acid group-containing monomer, an acetoacetyl group-containing monomer, etc. These functional group-containing monomers (a2) can be used alone or in combination of two or more.

[0060] Among them, a hydroxyl group-containing monomer (a2-1), a carboxyl group-containing monomer (a2-2), and an amino group-containing monomer (a2-3) are preferred.

[0061] In addition, when the acrylic resin (A) is an acrylic resin (A1) having an ethylenically unsaturated group described later, a hydroxyl group-containing monomer (a2-1), a carboxyl group-containing monomer (a2-2), and an amide group-containing monomer (a2-4) are preferred.

[0062] The content of the structural unit derived from the functional group-containing monomer (a2) in the acrylic resin (A) is usually 50% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, based on all the structural units of the acrylic resin (A). If the content is within the above range, there is a tendency for the storage stability to be improved, a tendency to be able to suppress crosslinking before the drying process, and excellent coatability. In addition, if the content is too large, there is a tendency for the storage stability to be reduced or crosslinking to occur before the drying process, and problems with coatability are likely to occur. In addition, if the content is too small, there is a tendency for the amount of introduction of the ethylenically unsaturated group to decrease and the peelability after the active energy ray irradiation to decrease.

[0063] In addition, when the aforementioned acrylic resin (A) is an acrylic resin (A1) having an ethylenically unsaturated group described later, the content of the structural unit derived from the functional group-containing monomer (a2) in the acrylic resin (A) before the introduction of the ethylenically unsaturated group is usually 0.1 to 60% by mass, preferably 1 to 50% by mass, more preferably 3 to 40% by mass, of all the structural units of the acrylic resin (A). If this content is too high, there is a tendency for the storage stability to decrease or for crosslinking to occur before the drying step, and problems are likely to arise in coatability. On the other hand, if this content is too low, there is a tendency for the amount of the introduced ethylenically unsaturated group to decrease and for the peelability after active energy ray irradiation to decrease.

[0064] The aforementioned acrylic resin (A) preferably has a structural unit derived from a hydroxyl group-containing monomer (a2-1). By using the aforementioned hydroxyl group-containing monomer (a2-1) as a copolymerization component of the acrylic resin (A), the acrylic resin (A) has a structural part derived from the hydroxyl group-containing monomer (a2), that is, a hydroxyl group. This hydroxyl group becomes a reaction site when introducing the ethylenically unsaturated group described later, and also becomes a reaction site with the crosslinking agent (D) described later.

[0065] As the aforementioned hydroxyl group-containing monomer (a2-1), a (meth)acrylate monomer containing a hydroxyl group is preferred. Specifically, examples thereof include (meth)acrylic acid 2-hydroxyethyl ester, (meth)acrylic acid 4-hydroxybutyl ester, (meth)acrylic acid 5-hydroxypentyl ester, (meth)acrylic acid 6-hydroxyhexyl ester, (meth)acrylic acid 8-hydroxyoctyl ester, etc. (meth)acrylic acid hydroxyalkyl esters; caprolactone-modified monomers such as caprolactone-modified (meth)acrylic acid 2-hydroxyethyl ester; oxyalkylene-modified monomers such as diethylene glycol (meth)acrylate and polyethylene glycol (meth)acrylate; primary hydroxyl group-containing monomers such as 2-acryloyloxyethyl-2-hydroxyethyl phthalate; secondary hydroxyl group-containing monomers such as (meth)acrylic acid 2-hydroxypropyl ester, (meth)acrylic acid 2-hydroxybutyl ester, and (meth)acrylic acid 3-chloro-2-hydroxypropyl ester; and tertiary hydroxyl group-containing monomers such as (meth)acrylic acid 2,2-dimethyl-2-hydroxyethyl ester. They can be used alone or in combination of two or more.

[0066] Among the aforementioned hydroxyl group-containing monomers, from the viewpoint of excellent reactivity with the ethylenically unsaturated compound and the crosslinking agent (D) described later, primary hydroxyl group-containing monomers are preferred, particularly preferably (meth)acrylic acid 2-hydroxyethyl ester and (meth)acrylic acid 4-hydroxybutyl ester, and more preferably (meth)acrylic acid 2-hydroxyethyl ester.

[0067] When the aforementioned acrylic resin (A) has a structural unit derived from the hydroxyl group-containing monomer (a2-1), its content is preferably 0.1 to 10% by mass, more preferably 0.2 to 8% by mass, still more preferably 0.4 to 6% by mass, and particularly preferably 0.6 to 5% by mass of all the structural units of the acrylic resin (A). If the content is within the aforementioned range, there is a tendency to easily obtain good coatability and adhesiveness.

[0068] In addition, when the aforementioned acrylic resin (A) is the acrylic resin (A1) containing an ethylenically unsaturated group described later, the content of the structural unit derived from the hydroxyl group-containing monomer (a2-1) in the acrylic resin (A) before introducing the ethylenically unsaturated group is usually 0.1 to 60% by mass, preferably 1 to 50% by mass, more preferably 3 to 40% by mass, and particularly preferably 7 to 30% by mass of all the structural units of the acrylic resin (A). If the content is too large, there is a tendency to crosslink before the drying step and problems with coatability are likely to occur. If the content is too small, the ethylenically unsaturated groups described later also become less, and therefore, there is a tendency for the decrease in adhesiveness to be insufficient and the contamination of the workpiece to be easily increased.

[0069] Examples of the aforementioned carboxyl group-containing monomer (a2-2) include (meth)acrylic acid, (meth)acrylic acid dimer, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, acrylamide N-glycolic acid, cinnamic acid, etc. Among them, from the viewpoint of copolymerizability, (meth)acrylic acid is preferred.

[0070] When the aforementioned acrylic resin (A) has a structural unit derived from the carboxyl group-containing monomer (a2-2), its content is usually 30% by mass or less, preferably 10% by mass or less, and more preferably 5% by mass or less of all the structural units of the acrylic resin (A). If the content is too large, there is a tendency to easily deteriorate the workpiece, a tendency for the storage stability to decrease, and a tendency to crosslink before the drying step and problems with coatability are likely to occur. In addition, the lower limit is usually 0.01% by mass.

[0071] Examples of the aforementioned amino group-containing monomer (a2-3) include (meth)acrylic acid aminoethyl ester, (meth)acrylic acid N,N-dimethylaminoethyl ester, (meth)acrylic acid N,N-dimethylaminopropyl ester, etc. Among them, (meth)acrylic acid N,N-dimethylaminoethyl ester is preferred.

[0072] The above-mentioned acrylic resin (A) has a structural unit derived from the amino group-containing monomer (a2-3), and its content is preferably 0.01 to 10% by mass, more preferably 0.05 to 8% by mass, and further preferably 0.1 to 5% by mass, based on all the structural units of the acrylic resin (A). When the content is within the above range, there is a tendency to easily obtain good coatability and adhesiveness.

[0073] Examples of the amide group-containing monomer (a2-4) include (meth)acrylamide-based monomers such as methoxydimethylpropanamide, ethoxymethyl(meth)acrylamide, n-butoxymethyl(meth)acrylamide, (meth)acryloylmorpholine, dimethyl(meth)acrylamide, diethyl(meth)acrylamide, dimethylaminopropyl(meth)acrylamide, (meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and the like. Among them, from the viewpoint of reducing the adhesiveness after exposure to high temperature and then irradiation with active energy rays, (meth)acryloylmorpholine is particularly preferred.

[0074] When the above-mentioned acrylic resin (A) has a structural unit derived from the amide group-containing monomer (a2-4), its content is usually 1 to 30% by mass, preferably 3 to 22% by mass, and more preferably 6 to 20% by mass, based on all the structural units of the acrylic resin (A). If the content is too small, there is a tendency that the reduction in adhesiveness after exposure to high temperature and then irradiation with active energy rays becomes insufficient. In addition, the glass transition temperature of the amide group-containing monomer (a2-4) is often high. If the content is too large, the glass transition temperature of the polymer will increase, and thus, there is a tendency that the reduction in adhesiveness after exposure to high temperature and then irradiation with active energy rays becomes insufficient.

[0075] Examples of the glycidyl group-containing monomer include glycidyl methacrylate, allyl glycidyl methacrylate, and the like.

[0076] When the above-mentioned acrylic resin (A) has a structural unit derived from the glycidyl group-containing monomer, its content is usually 20% by mass or less, preferably 10% by mass or less, and more preferably 5% by mass or less, based on all the structural units of the acrylic resin (A). If the content is too large, there is a tendency to crosslink before the drying process and problems with coatability are likely to occur.

[0077] Examples of the sulfonic acid group-containing monomer include olefin sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid, and methallyl sulfonic acid; 2-acrylamide-2-hydroxymethylpropanesulfonic acid, styrene sulfonic acid or its salts, and the like.

[0078] When the aforementioned acrylic resin (A) has a structural unit derived from a sulfonic acid group-containing monomer, its content is usually 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less, of all the structural units of the acrylic resin (A). If the content is too large, there is a tendency that crosslinking occurs before the drying step and coating properties are likely to have problems.

[0079] Examples of the aforementioned acetoacetyl group-containing monomer include 2-(acetoacetoxy)ethyl (meth)acrylate, allyl acetoacetate, and the like.

[0080] When the aforementioned acrylic resin (A) has a structural unit derived from an acetoacetyl group-containing monomer, its content is usually 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less, of all the structural units of the acrylic resin (A). If the content is too large, there is a tendency that crosslinking occurs before the drying step and coating properties are likely to have problems.

[0081] [Other copolymerizable monomer (a3)]

[0082] The aforementioned other copolymerizable monomer (a3) does not include (meth)acrylic acid alkyl ester (a1) and functional group-containing monomer (a2), and examples thereof include carboxylic acid vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl stearate, and vinyl benzoate; monomers containing an aromatic ring such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenyl diglycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, styrene, and α-methylstyrene; (meth)acrylate monomers containing a biphenoxy structure such as biphenoxyethyl (meth)acrylate; monomers containing an alkoxy group or an oxyalkylene group such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxy diglycol (meth)acrylate, ethoxy diglycol (meth)acrylate, methoxy polyethylene glycol (meth)acrylate, and polypropylene glycol mono(meth)acrylate; acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, dialkyl itaconate, dialkyl fumarate, allyl alcohol, acryloyl chloride, methyl vinyl ketone, allyl trimethyl ammonium chloride, dimethyl allyl vinyl ketone, and the like. They can be used alone or in combination of two or more.

[0083] When the aforementioned acrylic resin (A) has a structural unit derived from other copolymerizable monomer (a3), its content is usually 40% by mass or less, preferably 30% by mass or less, more preferably 25% by mass or less, of all the structural units of the acrylic resin (A). If the structural unit derived from other copolymerizable monomer (a3) is too large, there is a tendency that the adhesion characteristics are likely to decrease.

[0084] The aforementioned acrylic polymer (A) is obtained by polymerizing a copolymerization component containing an alkyl (meth)acrylate (a1), a functional group-containing monomer (a2), and, if necessary, other copolymerizable monomers (a3). As this polymerization method, generally known methods such as solution radical polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization are appropriately carried out. Among them, from the viewpoint of being able to safely and stably manufacture the acrylic resin (A) with an arbitrary monomer composition, solution radical polymerization is preferably used for manufacturing.

[0085] In the aforementioned solution radical polymerization, for example, copolymerization components such as an alkyl (meth)acrylate (a1), a functional group-containing monomer (a2), and, if necessary, other copolymerizable monomers (a3), and a polymerization initiator are mixed or dropped into an organic solvent, and polymerization is carried out under reflux conditions or usually at 50 to 98 °C for about 0.1 to 20 hours.

[0086] Examples of the organic solvent used in the aforementioned polymerization reaction include aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as hexane; esters such as ethyl acetate and butyl acetate; aliphatic alcohols such as n-propanol and isopropanol; and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

[0087] In addition, the amount of the aforementioned organic solvent is usually 10 to 900 parts by mass relative to 100 parts by mass of the copolymerization component.

[0088] As the aforementioned polymerization initiator, ordinary radical polymerization initiators can be used. Specifically, examples include azo-based polymerization initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile; peroxide-based polymerization initiators such as benzoyl peroxide, lauroyl peroxide, di-tert-butyl peroxide, and cumene hydroperoxide. They can be used alone or in combination of two or more.

[0089] In addition, the method for producing the aforementioned acrylic resin (A) can be free radical polymerization or living radical polymerization.

[0090] Examples of the aforementioned living radical polymerization method include the nitroxide method (TEMPO), atom transfer radical polymerization (ATRP) method, reversible addition-fragmentation chain transfer polymerization (RAFT) method, etc. Among these, from the viewpoints of monomer selectivity and ease of control, the ATRP method and the RAFT method are preferred. In the present invention, the RAFT method using a RAFT agent that does not employ a transition metal is particularly preferred.

[0091] The aforementioned RAFT method is a method of carrying out ordinary free radical polymerization in the presence of a RAFT agent. For example, a polymerization component, a RAFT agent, and a polymerization initiator are mixed in a reaction solvent and polymerized.

[0092] Furthermore, the acrylic resin (A) produced by living radical polymerization may be a random polymer or a triblock polymer.

[0093] Compared with free radical polymerization, the random polymer produced by the aforementioned living radical polymerization can obtain a random polymer with a narrow molecular weight distribution in high yield.

[0094] Specifically, the aforementioned triblock polymer is preferably manufactured through the following steps, for example:

[0095] (1) A step of mixing copolymerization component [I] containing a functional group monomer [such as functional group monomer (a2), etc.] and a monomer without a functional group [such as (meth)acrylic acid alkyl ester (a1), etc.] and a RAFT agent into a reaction solvent, adding a radical polymerization initiator, and polymerizing the polymerization component [I] to obtain a polymer segment (Y)-(Y) having a functional group;

[0096] (2) A step of using the polymer segment (Y)-(Y) obtained through the aforementioned step as a polymerization initiator, polymerizing the remaining polymerization component [II] in the presence of a RAFT agent, connecting with the polymer segment (Y) to manufacture a polymer segment (Z), and manufacturing an acrylic resin (A) having a structure of (Y)-(Z)-(Y).

[0097] In addition, when the acrylic resin (A) is an acrylic resin (A1) having an ethylenically unsaturated group, after the aforementioned step (2), it is preferably manufactured through the following step:

[0098] (3) A step of reacting the functional group of the polymer segment (Y) of (Y)-(Z)-(Y) obtained through the aforementioned step with an ethylenically unsaturated compound having a functional group that reacts with the functional group to obtain an acrylic resin (A1) having an ethylenically unsaturated group.

[0099] [[RAFT agent (chain transfer agent)]]

[0100] As the RAFT agent used in the aforementioned living radical polymerization, known compounds can be used, and for example, thiocarbonylthio compounds such as trithiocarbonyl-based, dithiocarbonyl-based, dithioester-based, and xanthate can be used.

[0101] Among the aforementioned RAFT agents, for the random polymer, for example, 3-((((1-carboxyethyl)thio)thioxocarbonyl)thio)propionic acid, bis[4-(methoxycarbonyl)benzyl]trithiocarbonate, bis[[4-[[ethyl-(2-acetoxyethyl)amino]carbonyl]phenyl]methyl] trithiocarbonate, and bis[[4-[[ethyl-(2-hydroxyethyl)amino]carbonyl]phenyl]methyl] trithiocarbonate of the trithiocarbonyl-based are preferably used.

[0102] In addition, among the aforementioned RAFT agents, for triblock polymers, from the viewpoints of being able to manufacture the polymer segments (Y)-(Y) at both ends of the acrylic resin through one process, having a low possibility of polymerization delay, being less prone to hydrolysis, and excellent manufacturing efficiency, a trithiocarbonyl-based RAFT agent is preferred, and bis[4-(methoxycarbonyl)benzyl] trithiocarbonate, bis[[4-[[ethyl-(2-acetoxyethyl)amino]carbonyl]phenyl]methyl] trithiocarbonate, and bis[[4-[[ethyl-(2-hydroxyethyl)amino]carbonyl]phenyl]methyl] trithiocarbonate are particularly preferred.

[0103] The glass transition temperature (Tg) of the aforementioned acrylic resin (A) obtained by such operation is preferably -60 to 0 °C, more preferably -55 to -10 °C, and further preferably -52 to -30 °C. If the glass transition temperature is too high, there is a tendency for the adhesiveness to decrease, and if it is too low, there is a tendency for the contamination to the processed member to increase.

[0104] It should be noted that the aforementioned glass transition temperature (Tg) refers to the value calculated by substituting the glass transition temperature and mass fraction of each monomer constituting the acrylic resin (A) into the following Fox formula when making it into a homopolymer.

[0105] [Mathematical formula 1]

[0106]

[0107] Tg: Glass transition temperature of acrylic resin (A) (K)

[0108] Tga: Glass transition temperature of homopolymer of monomer A (K)

[0109] Wa: Mass fraction of monomer A

[0110] Tgb: Glass transition temperature of homopolymer of monomer B (K)

[0111] Wb: Mass fraction of monomer B

[0112] Tgn: Glass transition temperature of homopolymer of monomer N (K)

[0113] Wn: Mass fraction of monomer N

[0114] (Wa + Wb +... + Wn = 1)

[0115] Here, when making a homopolymer of the monomer constituting the acrylic resin (A), the glass transition temperature is usually measured using a differential scanning calorimeter (DSC), and the measurement can be carried out according to the methods of JIS K 7121-1987 and JIS K 6240.

[0116] In addition, the weight average molecular weight of the acrylic resin (A) is usually 100,000 to 2,500,000, preferably 150,000 to 2,000,000, particularly preferably 200,000 to 1,500,000, and especially preferably 300,000 to 1,000,000. If the weight average molecular weight is too small, there is a tendency for the contamination of the processed member to be high. If it is too large, there is a tendency for the coating property to be easily reduced or it becomes disadvantageous in terms of cost.

[0117] Furthermore, the dispersity (weight average molecular weight / number average molecular weight) of the acrylic resin (A) is preferably 20 or less, particularly preferably 10 or less, more preferably 7 or less, and especially preferably 6 or less. If the dispersity is too high, there is a tendency for the contamination of the processed member to increase. It should be noted that from the viewpoint of the manufacturing limit, the lower limit of the dispersity is usually 1.1.

[0118] The weight average molecular weight of the aforementioned acrylic resin (A) is the weight average molecular weight based on the conversion of the standard polystyrene molecular weight, which is measured by serially using 3 columns in a high performance liquid chromatograph (manufactured by Waters Corporation, Japan, "Waters 2695 (main body)" and "Waters 2414 (detector)"): Shodex GPC KF-806L (exclusion limit molecular weight: 2×10 7 , separation range: 100 to 2×10 7 , theoretical plate number: 10,000 plates / root, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm), and the number average molecular weight can also be obtained by the same method.

[0119] In addition, the viscosity of the 30 mass% solution of the aforementioned acrylic resin (A) at 25 °C is preferably 5 to 20,000 mPa·s, more preferably 100 to 10,000 mPa·s. If the viscosity is outside the aforementioned range, there is a tendency for the coating property to decrease. It should be noted that the measurement method of the aforementioned viscosity is based on a B-type viscometer (rotor M3, rotation speed 6 rpm).

[0120] The aforementioned acrylic resin (A) can be used directly, or an ethylenically unsaturated group can be introduced into the acrylic resin (A) to produce an acrylic resin (A1) having an ethylenically unsaturated group. By using the acrylic resin (A) as the acrylic resin (A1) having an ethylenically unsaturated group, when irradiated with active energy rays, the ethylenically unsaturated group polymerizes and cures, resulting in a decrease in adhesive strength. Therefore, when this adhesive composition contains the acrylic resin (A1) having an ethylenically unsaturated group, even without the urethane (meth)acrylate compound (B) described later, when this adhesive composition is made into an adhesive sheet, peelability can be imparted.

[0121] As a method for introducing an ethylenically unsaturated group into the aforementioned acrylic resin (A), it is only necessary to react the acrylic resin (A) with a compound containing an ethylenically unsaturated group. Examples thereof include:

[0122] (i) A method of reacting the hydroxyl group of the acrylic resin (A) with an ethylenically unsaturated compound containing an isocyanate group;

[0123] (ii) A method of reacting the hydroxyl group of the acrylic resin (A) with (meth)acrylic anhydride;

[0124] (iii) A method of reacting the hydroxyl group of the acrylic resin (A) with a carboxylic acid containing an ethylenically unsaturated group;

[0125] (iv) A method of reacting the carboxyl group of the acrylic resin (A) with a (meth)acrylate containing a vinyl ether group, etc.

[0126] Among them, from the viewpoint of reactivity, method (i) is preferred.

[0127] Hereinafter, (i) which is a preferred method will be described.

[0128] In the aforementioned method (i), the hydroxyl group derived from the hydroxyl-containing monomer (a2-1) of the acrylic resin (A) reacts with the isocyanate group of the aforementioned ethylenically unsaturated compound containing an isocyanate group, and an ethylenically unsaturated group containing an ethylenically unsaturated bond and a urethane bond is introduced into the acrylic resin (A), and an acrylic resin (A1) having an ethylenically unsaturated group can be obtained.

[0129] [Ethylenically unsaturated compound containing an isocyanate group]

[0130] The aforementioned ethylenically unsaturated compound containing an isocyanate group is a monomer having an isocyanate group and an ethylenically unsaturated group capable of polymerization.

[0131] Examples of the above-mentioned ethylenically unsaturated compound containing an isocyanate group include 2-(meth)acryloyloxyethyl isocyanate, 3-(meth)acryloyloxypropyl isocyanate, 2-(meth)acryloyloxyisopropyl isocyanate, 4-(meth)acryloyloxybutyl isocyanate, 2-(meth)acryloyloxytert-butyl isocyanate, 2-(meth)acryloyloxybutyl-4-isocyanate, 2-(meth)acryloyloxybutyl-3-isocyanate, 2-(meth)acryloyloxybutyl-2-isocyanate, 2-(meth)acryloyloxybutyl-1-isocyanate, 5-(meth)acryloyloxypentyl isocyanate, 6-(meth)acryloyloxyhexyl isocyanate, 7-(meth)acryloyloxyheptyl isocyanate, 2-(isocyanatoethoxy)ethyl (meth)acrylate, 3-(meth)acryloyloxy phenyl isocyanate, 4-(meth)acryloyloxy phenyl isocyanate, 1,1-bis((meth)acryloxymethyl)methyl isocyanate, 1,1-bis((meth)acryloxymethyl)ethyl isocyanate, 2'-pentenoyl-4-oxy phenyl isocyanate, etc. They may be used alone or in combination of two or more.

[0132] Among these compounds, especially from the viewpoints of ease of synthesis and ease of obtaining raw materials, (meth)acrylate monomers are preferred, and 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, 2-(isocyanatoethoxy)ethyl methacrylate, 2-(isocyanatoethoxy)ethyl acrylate, and 1,1-bis(acryloxymethyl)ethyl isocyanate are more preferred.

[0133] The use ratio of the acrylic resin (A) and the ethylenically unsaturated compound containing an isocyanate group in the reaction between them can be appropriately set in consideration of the ratio of hydroxyl group to isocyanate group, and it varies depending on the types of the two compounds. Usually, relative to 100 mol% of the structural unit derived from the hydroxyl group-containing monomer (a2-1) in the acrylic resin (A), the ethylenically unsaturated compound containing an isocyanate group is 10 to 100 mol%, preferably 20 to 97 mol%, and particularly preferably 30 to 95 mol%.

[0134] In addition, the reaction between the two compounds can be carried out in the presence of a reaction catalyst, and the reaction rate can be adjusted by the addition amount of the reaction catalyst.

[0135] As the aforementioned reaction catalyst, known reaction catalysts can be used. Specific examples of the reaction catalyst include, for example, dibutyltin dilaurate, copper naphthenate, cobalt naphthenate, zinc naphthenate, triethylamine, 1,4-diazabicyclo[2.2.2]octane, zirconium acetylacetonate, diisopropoxybis(ethylacetoacetato)titanium, a mixture of bismuth tris(2-ethylhexanoate) and 2-ethylhexanoic acid, etc. One kind selected from these reaction catalysts can be used alone, or two or more kinds can be used in combination.

[0136] When reacting two compounds, the reaction temperature is preferably 25 to 100 °C, more preferably 30 to 60 °C. The reaction time is preferably 30 minutes to 50 hours, more preferably 3 hours to 20 hours.

[0137] When reacting two compounds, a polymerization inhibitor and an antioxidant can be added to the reaction system as needed. As the polymerization inhibitor, commonly used polymerization inhibitors can be used. Specific examples of the polymerization inhibitor include hydroquinone, 4-methoxyphenol, etc. As the antioxidant, hindered phenol antioxidants and phenolic antioxidants can be used. Specifically, 2,6-di-tert-butyl-4-methylphenol (BHT), etc. can be cited.

[0138] In addition, when reacting two compounds, known additives can be added according to the purpose.

[0139] The addition reaction rate of the hydroxyl group derived from the hydroxyl group-containing monomer (a2-1) in the aforementioned acrylic resin (A) and the isocyanate group of the ethylenically unsaturated compound containing an isocyanate group, that is, the urethanization rate is preferably 5 to 99%, more preferably 10 to 90%. If the urethanization rate is too low, there is a tendency that the adhesive strength after irradiation with active energy rays such as ultraviolet rays is difficult to sufficiently decrease. If the urethanization rate is too high, there is a tendency that the urethane reaction will not be completed and the ethylenically unsaturated compound containing an unreacted isocyanate group will remain.

[0140] As a method for calculating the urethanization rate, it can be calculated according to, for example, the ratio of the amount (mol) of the isocyanate group of the ethylenically unsaturated compound containing an isocyanate group to the amount (mol) of the hydroxyl group of the acrylic resin (A). It should be noted that by confirming the disappearance of the peak of the isocyanate group by IR measurement, it is determined that 100% of the introduced isocyanate group has reacted.

[0141] In addition, as another method for calculating the urethanization rate, there is a method of calculating based on the ratio of the integral values of the structural units derived from the hydroxyl group-containing monomer (a2-1) before and after the urethanization reaction by 1 1H-NMR measurement.

[0142] Among the above, the preferred method for introducing an ethylenically unsaturated group into the acrylic resin (A), that is, method (i), has been described. However, by following the conventional method also in the above methods (ii) to (iv), it is possible to introduce an ethylenically unsaturated group into the acrylic resin (A).

[0143] The content of the ethylenically unsaturated group in the above acrylic resin (A1) having an ethylenically unsaturated group is usually 5 to 250 mmol / 100 g, preferably 30 to 200 mmol / 100 g, and more preferably 50 to 160 mmol / 100 g. If the content of the ethylenically unsaturated group is too small, there is a tendency for the peelability achieved by active energy ray irradiation to decrease. If the content of the ethylenically unsaturated group is too large, there is a tendency for the adhesiveness before active energy ray irradiation to decrease.

[0144] The content of the above ethylenically unsaturated group can be determined by the following formula.

[0145] Content of ethylenically unsaturated group (mmol / 100 g)

[0146] = mmol of hydroxyl groups contained in 100 g of the acrylic resin (A) before addition of the ethylenically unsaturated group × addition reaction rate (%) / mass (g) of 100 g of the acrylic resin (A1) having an ethylenically unsaturated group × 100

[0147] The glass transition temperature (Tg) of the above acrylic resin (A1) having an ethylenically unsaturated group is preferably -65 to 0 °C, particularly preferably -60 to -10 °C, further preferably -55 to -20 °C, and especially preferably -52 to -30 °C. If the glass transition temperature is too high, there is a tendency for the adhesiveness to decrease. If it is too low, there is a tendency for the contamination of the processed member to increase. It should be noted that the above glass transition temperature (Tg) can be calculated by the above method.

[0148] In addition, the weight average molecular weight of the above acrylic resin (A1) having an ethylenically unsaturated group is usually 100,000 to 2,500,000, preferably 150,000 to 2,000,000, particularly preferably 200,000 to 1,500,000, and especially preferably 300,000 to 1,000,000. If the weight average molecular weight is too small, there is a tendency for the contamination of the processed member to become high. If it is too large, there is a tendency for the coatability to be easily reduced or for it to be disadvantageous in terms of cost.

[0149] Furthermore, the dispersity (weight average molecular weight / number average molecular weight) of the acrylic resin (A1) having an ethylenically unsaturated group is preferably 20 or less, particularly preferably 15 or less, more preferably 10 or less, and especially preferably 7 or less. If the dispersity is too high, there is a tendency for the contamination of the workpiece to increase. It should be noted that from the perspective of manufacturing limitations, the lower limit of the dispersity is usually 1.1.

[0150] It should be noted that the weight average molecular weight and dispersity of the acrylic resin (A1) having an ethylenically unsaturated group can be measured by the aforementioned method.

[0151] The viscosity of the acrylic resin (A1) having an ethylenically unsaturated group at 25°C is preferably 5 to 20,000 mPa·s, more preferably 500 to 10,000 mPa·s. If the viscosity is outside the aforementioned range, there is a tendency for the coatability to decrease. It should be noted that the measurement method of the aforementioned viscosity is based on a B-type viscometer (rotor M3, rotation speed 6 rpm).

[0152] In addition, from the perspective of the reactivity with the crosslinking agent (D) described later, the acrylic resin (A1) having an ethylenically unsaturated group preferably has a structural unit derived from a hydroxyl group-containing monomer (a2-1), that is, it preferably has a hydroxyl group.

[0153] The hydroxyl group content of the acrylic resin (A1) having an ethylenically unsaturated group is usually 0.01 to 40% by mass, preferably 1 to 30% by mass, and more preferably 10 to 25% by mass. If it is within the above range, the effects of the present invention become more excellent. On the contrary, if the hydroxyl group content is too small, there is a tendency for the cohesion of the adhesive to decrease, resulting in residual glue. If the hydroxyl group content is too large, there is a tendency for the softness and adhesiveness of the adhesive to decrease, and floating occurs between the workpieces.

[0154] 〔Nitroso compound (B)〕

[0155] This adhesive composition contains a nitroso compound (B). In addition, the aforementioned nitroso compound (B) is usually used as a polymerization inhibitor.

[0156] It is speculated that if the aforementioned acrylic resin (A) is exposed to high temperature, an alkyl radical is generated, and then, it reacts with oxygen to generate a peroxy radical. This peroxy radical abstracts hydrogen from the acrylic resin (A) to generate an alkyl radical, and itself becomes a hydroperoxide. Furthermore, the aforementioned hydroperoxide decomposes, and new radicals are generated due to its decomposition. Therefore, the deterioration of the acrylic resin (A) accelerates.

[0157] In addition, an adhesive composition that cures by actinic energy rays usually cures due to free radicals. Therefore, there is also a problem of curing due to heat before curing by actinic energy rays.

[0158] In the present invention, by using the nitroso compound (B), the alkyl radicals are stabilized, the deterioration of the acrylic resin (A) is suppressed, and further, the curing achieved by the alkyl radicals is suppressed. Therefore, the effects of the present invention can be obtained.

[0159] Examples of the nitroso compound (B) include aromatic nitroso compounds such as nitrobenzene, 2-nitrosotoluene, 1,2,4,5-tetramethyl-3-nitroso benzene, 4-nitrosophenol, 1-nitroso-2-naphthol, 2-nitroso-1-naphthol, 4-nitrosodiphenylamine, 3,5-dibromo-4-nitrobenzenesulfonic acid, N-tert-butyl-N-nitrosoaniline, ammonium N-nitrosophenylhydroxylamine, and aluminum N-nitrosophenylhydroxylamine; heterocyclic nitroso compounds such as N-nitrosopyrrolidine, 1-nitrosopiperidine, and 4-nitrosomorpholine; and aliphatic nitroso compounds such as N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitroso-N-methylbutylamine, N-nitroso-N-ethylurea, and N-nitrosohexamethyleneimine. They can be used alone or in combination of two or more. Among them, from the viewpoint of compatibility, aromatic nitroso compounds are preferred, ammonium N-nitrosophenylhydroxylamine and / or aluminum N-nitrosophenylhydroxylamine are more preferred, and aluminum N-nitrosophenylhydroxylamine is particularly preferred.

[0160] The content of the nitroso compound (B) is usually 0.01 to 1 part by mass, preferably 0.05 to 0.8 part by mass, and particularly preferably 0.1 to 0.5 part by mass with respect to 100 parts by mass of the acrylic resin (A).

[0161] In addition, the content of the nitroso compound (B) is usually 0.01 to 10 parts by mass, preferably 0.1 to 5 parts by mass, and more preferably 0.2 to 1 part by mass with respect to 100 parts by mass of the urethane (meth)acrylate compound (C).

[0162] Furthermore, the mass ratio of the nitroso compound (B) to the photopolymerization initiator (E) described later [nitroso compound (B) / photopolymerization initiator (E)] is usually 1 / 50 to 1 / 1, preferably 1 / 20 to 1 / 2.

[0163] By setting the content of the nitroso compound (B) within the aforementioned range, the heat resistance becomes excellent. In addition, if the content of the nitroso compound (B) is too small, there is a tendency that the decrease in adhesion after irradiation with active energy rays after heating becomes insufficient, and if it is too large, there is a tendency that the radicals generated by the photoinitiator (E) are trapped during irradiation with active energy rays and the decrease in adhesion after irradiation with active energy rays becomes insufficient.

[0164] 〔Urethane (meth) acrylate compound (C)〕

[0165] This adhesive composition exhibits active energy ray curability when irradiated with active energy rays. Therefore, it preferably contains a urethane (meth) acrylate compound (C). In particular, when this adhesive composition does not contain an acrylic resin (A1) having an ethylenically unsaturated group, it preferably contains a urethane (meth) acrylate compound (C).

[0166] The aforementioned urethane (meth) acrylate compound (C) refers to a compound having a urethane bond and a (meth) acryloyl group.

[0167] The aforementioned urethane (meth) acrylate compound (C) may be a urethane (meth) acrylate compound (C1), which is a reaction product of a (meth) acrylate compound (c1) containing a hydroxyl group and a polyisocyanate compound (c2), or a urethane (meth) acrylate compound (C2), which is a reaction product of a (meth) acrylate compound (c1) containing a hydroxyl group, a polyisocyanate compound (c2), and a polyol compound (c3).

[0168] It should be noted that the aforementioned urethane (meth) acrylate compound (C) may be used alone or in combination of two or more.

[0169] As the aforementioned hydroxy group-containing (meth)acrylate compound (c1), it preferably has one hydroxy group, and examples thereof include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate; 2-hydroxyethyl acryloyl phosphate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, dipropylene glycol (meth)acrylate, fatty acid-modified glycidyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate and other hydroxy group-containing (meth)acrylate compounds having one ethylenically unsaturated group; glycerol di(meth)acrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate and other hydroxy group-containing (meth)acrylate compounds having two ethylenically unsaturated groups; pentaerythritol tri(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, ethylene oxide-modified dipentaerythritol penta(meth)acrylate and other hydroxy group-containing (meth)acrylate compounds having three or more ethylenically unsaturated groups, etc.

[0170] The aforementioned hydroxy group-containing (meth)acrylate compound (c1) can be used alone or in combination of two or more.

[0171] Among these, from the viewpoint of excellent curability after irradiation with active energy rays, a hydroxy group-containing (meth)acrylate compound having three or more ethylenically unsaturated groups is preferred, and pentaerythritol tri(meth)acrylate and dipentaerythritol penta(meth)acrylate are particularly preferred.

[0172] As the aforementioned polyisocyanate compound (C2), for example, aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, naphthalene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, lysine triisocyanate; alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate; or isocyanurate bodies or polymer compounds of these polyisocyanates, urethane group polyisocyanates, biuret type polyisocyanates, water-dispersible polyisocyanates, etc. can be cited. They can be used alone or in combination of two or more.

[0173] Among these, from the viewpoint of excellent reactivity and versatility, aromatic polyisocyanates such as tolylene diisocyanate are preferred; aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate; alicyclic diisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate are particularly preferred, and tolylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate are more preferred, and tolylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate are further preferred.

[0174] As the aforementioned polyol compound (C3), as long as it is a compound containing two or more hydroxyl groups, for example, aliphatic polyols, alicyclic polyols, polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, polybutadiene polyols, polyisoprene polyols, (meth)acrylic polyols, polysiloxane polyols, etc. can be cited. They can be used singly or in combination of two or more.

[0175] Examples of the aforementioned aliphatic polyols include aliphatic alcohols having two hydroxyl groups such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, dimethylolpropane, neopentyl glycol, 2,2 - diethyl - 1,3 - propanediol, 2 - butyl - 2 - ethyl - 1,3 - propanediol, 1,4 - tetramethylene glycol, 1,3 - tetramethylene glycol, 2 - methyl - 1,3 - trimethylene glycol, 1,5 - pentamethylene glycol, 1,6 - hexamethylene glycol, 3 - methyl - 1,5 - pentamethylene glycol, 2,4 - diethyl - 1,5 - pentamethylene glycol, pentaerythritol diacrylate, 1,9 - nonanediol, 2 - methyl - 1,8 - octanediol, etc.; sugar alcohols such as xylitol and sorbitol; aliphatic polyols having three or more hydroxyl groups such as glycerol, trimethylolpropane, and trimethylolethane, etc.

[0176] Examples of the aforementioned alicyclic polyols include cyclohexanediols such as 1,4 - cyclohexanediol and cyclohexanedimethanol; hydrogenated bisphenols such as hydrogenated bisphenol A; tricyclodecane dimethanol, etc.

[0177] Examples of the aforementioned polyether - type polyols include polyether - type polyols having an alkylene structure such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, polypentamethylene glycol, and polyhexamethylene glycol; random copolymers or block copolymers of these polyalkylene glycols, etc.

[0178] Examples of the aforementioned polyester - type polyols include condensation polymers of polyols and polycarboxylic acids; ring - opening polymers of cyclic esters (lactones); reaction products based on three components of polyols, polycarboxylic acids, and cyclic esters, etc.

[0179] Examples of the aforementioned polyols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4 - tetramethylene glycol, 1,3 - tetramethylene glycol, 2 - methyl - 1,3 - trimethylene glycol, 1,5 - pentamethylene glycol, neopentyl glycol, 1,6 - hexamethylene glycol, 3 - methyl - 1,5 - pentamethylene glycol, 2,4 - diethyl - 1,5 - pentamethylene glycol, glycerol, trimethylolpropane, trimethylolethane, cyclohexanediols (such as 1,4 - cyclohexanediol), bisphenols (such as bisphenol A), sugar alcohols (such as xylitol and sorbitol), etc.

[0180] Examples of the aforementioned polycarboxylic acids include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid; alicyclic dicarboxylic acids such as 1,4 - cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 2,6 - naphthalenedicarboxylic acid, terephthalic acid, trimellitic acid, etc.

[0181] Examples of the aforementioned cyclic esters include, for example, propiolactone, β-methyl-δ-valerolactone, ε-caprolactone, etc.

[0182] Examples of the aforementioned polycarbonate polyols include, for example, the reaction product of a polyol and phosgene; the ring-opening polymer of a cyclic carbonate (such as an alkylene carbonate, etc.). Examples of the aforementioned polyol include the polyols exemplified in the description of the aforementioned polyester polyols, etc. Examples of the aforementioned alkylene carbonate include, for example, ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, hexamethylene carbonate, etc.

[0183] It should be noted that the polycarbonate polyol only needs to be a compound having a carbonate bond in the molecule and a hydroxyl group at the end, and may have a carbonate bond and an ester bond together.

[0184] Examples of the aforementioned polyolefin polyols include polyolefin polyols having a homopolymer or copolymer of ethylene, propylene, butene, etc. as a saturated hydrocarbon skeleton and having a hydroxyl group at the molecular end.

[0185] Examples of the aforementioned polybutadiene polyols include polybutadiene polyols having a copolymer of butadiene as a hydrocarbon skeleton and having a hydroxyl group at the molecular end.

[0186] The polybutadiene polyol may be a hydrogenated polybutadiene polyol obtained by hydrogenating all or part of the ethylenically unsaturated groups contained in its structure.

[0187] Examples of the aforementioned polyisoprene polyols include polyisoprene polyols having a copolymer of isoprene as a hydrocarbon skeleton and having a hydroxyl group at the molecular end.

[0188] The polyisoprene polyol may be a hydrogenated polyisoprene polyol obtained by hydrogenating all or part of the ethylenically unsaturated groups contained in its structure.

[0189] Examples of the aforementioned (meth)acrylic polyols include (meth)acrylic polyols having at least 2 hydroxyl groups in the molecule of a polymer or copolymer of a (meth)acrylate. Examples of the (meth)acrylate include, for example, (meth)acrylic acid alkyl esters such as (meth)methyl acrylate, (meth)ethyl acrylate, (meth)propyl acrylate, (meth)butyl acrylate, (meth)hexyl acrylate, (meth)octyl acrylate, 2-ethylhexyl (meth)acrylate, (meth)decyl acrylate, (meth)dodecyl acrylate, (meth)octadecyl acrylate, etc.

[0190] Examples of the aforementioned polysiloxane polyols include, for example, dimethyl polysiloxane polyols, methylphenyl polysiloxane polyols, etc.

[0191] Among these, aliphatic polyols and alicyclic polyols are preferably used. From the perspective of versatility, polyester polyols, polyether polyols, and polycarbonate polyols are preferably used.

[0192] The weight-average molecular weight of the aforementioned polyol compound (c3) is preferably 60 to 5000, particularly preferably 100 to 3000, and further preferably 150 to 2000. If the weight-average molecular weight of the polyol compound (c3) is too large, there is a tendency that the resulting urethane (meth)acrylate compound (C2) and the acrylic resin (A) are not easily mixed uniformly, and residual glue is likely to be generated on the processed member. On the other hand, if the weight-average molecular weight of the polyol compound (c3) is too small, there is a tendency that cracks are likely to occur in the adhesive layer after irradiation with active energy rays.

[0193] The aforementioned urethane (meth)acrylate compound (C) is preferably a reaction product of a (meth)acrylate compound containing a hydroxyl group and a polyisocyanate compound (c2), and the (meth)acrylate compound containing a hydroxyl group contains 3 or more ethylenically unsaturated groups in the molecule.

[0194] The aforementioned urethane (meth)acrylate compound (C) can be produced by reacting the aforementioned components using known reaction means.

[0195] Generally, in the case of the urethane (meth)acrylate compound (C1), the aforementioned (meth)acrylate compound containing a hydroxyl group (c1) and the polyisocyanate compound (c2) are charged into the reactor together or separately. In the case of the urethane (meth)acrylate compound (C2), the polyol compound (c3) is further charged into the reactor together or separately, and a urethanization reaction is caused to occur using known reaction means, thereby enabling production. In addition, in the case of producing the urethane (meth)acrylate compound (C2), from the viewpoints of the stability of the urethanization reaction and reduction of by-products, a method in which the (meth)acrylate compound containing a hydroxyl group (c1) is reacted with a reaction product obtained by previously reacting the polyol compound (c3) and the polyisocyanate compound (c2) is useful.

[0196] In the reaction between the aforementioned (meth)acrylate compound containing a hydroxyl group (c1) and the polyisocyanate compound (c2), a reaction catalyst is preferably used for the purpose of promoting the reaction.

[0197] Examples of the reaction catalyst described above include organometallic compounds such as dibutyltin dilaurate, trimethyltin hydroxide, and tetra-n-butyltin; metal salts such as zinc octenoate, tin octenoate, tin octoate, cobalt naphthenate, stannous chloride, and tin chloride; amine-based catalysts such as triethylamine, benzyldiethylamine, 1,4-diazabicyclo[2,2,2]octane, 1,8-diazabicyclo[5,4,0]undecene, N,N,N',N'-tetramethyl-1,3-butanediamine, and N-ethylmorpholine; bismuth nitrate, bismuth bromide, bismuth iodide, bismuth sulfide; and organobismuth compounds such as dibutylbismuth dilaurate and dioctylbismuth dilaurate; bismuth-based catalysts such as bismuth salts of organic acids like bismuth 2-ethylhexanoate, bismuth naphthenate, bismuth isodecanoate, bismuth neodecanoate, bismuth laurate, bismuth maleate, bismuth stearate, bismuth oleate, bismuth linoleate, bismuth acetate, bisneodecanoate bismuth, dibismuth salicylate, and dibismuth gallate; zirconium-based catalysts such as inorganic zirconium, organic zirconium, and zirconium element; reaction catalysts obtained by using two or more catalysts in combination such as zinc 2-ethylhexanoate / zirconium tetraacetylacetonate. Among them, dibutyltin dilaurate and 1,8-diazabicyclo[5,4,0]undecene are suitable. It should be noted that these catalysts can be used alone or in combination of two or more. Among them, dibutyltin dilaurate and 1,8-diazabicyclo[5,4,0]undecene are preferred.

[0198] In the aforementioned carbamate esterification reaction, organic solvents that do not have functional groups that react with isocyanate groups can be used, such as esters like ethyl acetate and butyl acetate; ketones like methyl ethyl ketone and methyl isobutyl ketone; and aromatic compounds like toluene and xylene.

[0199] In addition, the reaction temperature is generally 30 to 90 °C, preferably 40 to 80 °C, and the reaction time is generally 2 to 10 hours, preferably 3 to 8 hours.

[0200] The aforementioned carbamate esterification reaction is terminated at the time when the content of residual isocyanate groups in the reaction system becomes 0.5% by mass or less, whereby a urethane (meth)acrylate-based compound (C) can be obtained.

[0201] From the viewpoint of the peelability after irradiation with active energy rays, the urethane (meth)acrylate-based compound (C) obtained by such operation preferably has 5 to 20 ethylenically unsaturated groups, more preferably 5 to 18, and particularly preferably 6 to 15.

[0202] If the number of the ethylenically unsaturated groups is too large, the crosslinking density after irradiation with active energy rays becomes too large, and cracks are likely to occur in the adhesive layer. If it is too small, a sufficient crosslinking density cannot be obtained, and thus there is a tendency that it is difficult to peel after irradiation with active energy rays.

[0203] The weight-average molecular weight of the aforementioned urethane (meth)acrylate compound (C) is generally 500 to 10,000, preferably 750 to 5,000, and more preferably 1,000 to 4,000. If the weight-average molecular weight is too large, there is a tendency for the viscosity of the urethane (meth)acrylate compound (C) to increase, the compatibility with the acrylic resin (A) to decrease, and for residual glue to easily occur on the workpiece to be processed. If the weight-average molecular weight is too small, there is a tendency for the urethane (meth)acrylate compound (C) to ooze out from the adhesive sheet and for residual glue to easily occur.

[0204] It should be noted that the weight-average molecular weight of the aforementioned urethane (meth)acrylate compound (C) is the weight-average molecular weight converted based on the standard polystyrene molecular weight, and is measured by serially using four columns: ACQUITY APC XT 450×1 piece, ACQUITY APC XT 200×1 piece, and ACQUITY APC XT 45×2 pieces in a high-performance liquid chromatograph (manufactured by Waters Corporation, "ACQUITY APC system").

[0205] The viscosity of the urethane (meth)acrylate compound (C) used in the present invention at 60°C is preferably 500 to 100,000 mPa·s, and particularly preferably 1,000 to 50,000 mPa·s. When the viscosity is outside the aforementioned range, there is a tendency for the coatability to decrease. It should be noted that the viscosity can be measured using an E-type viscometer.

[0206] The content of the aforementioned urethane (meth)acrylate compound (C) is generally 20 to 200 parts by mass, preferably 25 to 150 parts by mass, and particularly preferably 30 to 100 parts by mass with respect to 100 parts by mass of the acrylic resin (A). If the content of the urethane (meth)acrylate compound (C) is too small, there is a tendency for the peelability after active energy ray irradiation to easily decrease. If it is too large, there is a tendency for cracks to easily occur in the adhesive layer after active energy ray irradiation.

[0207] 〔Crosslinking agent (D)〕

[0208] In this adhesive composition, in order to improve the adhesive strength before active energy ray irradiation, it is preferably further contained a crosslinking agent (D).

[0209] As described above, the crosslinking agent (D) is a crosslinking agent that reacts with the functional groups in the acrylic resin (A) to form a crosslinked structure. Examples thereof include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, aldehyde-based crosslinking agents, amine-based crosslinking agents, and metal chelate-based crosslinking agents. Among these, from the viewpoints of improving the adhesiveness to the adherend and the reactivity with the acrylic resin (A), an isocyanate-based crosslinking agent is preferred.

[0210] The aforementioned isocyanate-based crosslinking agent contains at least two or more isocyanate groups. Examples thereof include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and their biuret bodies, isocyanurate bodies, and adducts, where the adducts are reaction products formed with compounds containing low molecular active hydrogen such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, from the viewpoints of chemical resistance and reactivity with functional groups, aromatic polyisocyanates and adducts of aromatic polyisocyanates and trimethylolpropane are preferred, and an adduct of toluene diisocyanate and trimethylolpropane is particularly preferred.

[0211] Examples of the aforementioned epoxy-based crosslinking agent include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, and diglycidylamine.

[0212] Examples of the aforementioned aziridine-based crosslinking agent include diphenylmethane-4,4'-bis(1-aziridinecarboxamide), trimethylolpropane tris-β-aziridinylpropionate, tetramethylolmethane tris-β-aziridinylpropionate, toluene-2,4-bis(1-aziridinecarboxamide), triethylenetrismelamine, bisisophthaloyl-1-(2-methylaziridine), tris-1-(2-methylaziridine)phosphine, and trimethylolpropane tris-β-(2-methylaziridine)propionate.

[0213] As the aforementioned melamine-based crosslinking agent, examples thereof include melamine, amino group-containing hydroxymethyl melamine obtained by condensing melamine and formaldehyde, imino group-containing hydroxymethyl melamine, hydroxymethyl melamine derivatives such as hexahydroxymethyl melamine; partially or completely alkylated hydroxymethyl melamine obtained by reacting a hydroxymethyl melamine derivative with a lower alcohol such as methanol or butanol for partial or complete etherification, alkylated hydroxymethyl melamine such as imino group-containing partially or completely alkylated hydroxymethyl melamine, and the like.

[0214] Examples of the aforementioned aldehyde-based crosslinking agent include aldehyde-based compounds that liberate aldehydes in an aqueous solution, such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, glyoxal, glutaraldehyde, dialdehyde starch, hexamethylenetetramine, 1,4-dioxane-2,3-diol, 1,3-bis(hydroxymethyl)-2-imidazolidone, dimethylolurea, N-hydroxymethylacrylamide, urea-formaldehyde resin, melamine formaldehyde resin, etc.; or aromatic aldehyde-based compounds such as benzaldehyde, 2-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, etc.

[0215] Examples of the aforementioned amine-based crosslinking agent include 4,4'-methylenebis(2-chloroaniline), modified-4,4'-methylenebis(2-chloroaniline), diethyltoluenediamine.

[0216] Examples of the aforementioned metal chelate-based crosslinking agent include chelate compounds in which the metal atom is aluminum, zirconium, titanium, zinc, iron, tin, etc. From the viewpoint of performance, an aluminum chelate compound is preferably used. Examples of the aluminum chelate compound include diisopropoxyaluminum monooleylacetoacetate, monoisopropoxyaluminum dioleylacetoacetate, monoisopropoxyaluminum monooleate monoethylacetoacetate, diisopropoxyaluminum monolaurylacetoacetate, diisopropoxyaluminum monostearylacetoacetate, diisopropoxyaluminum monoisostearylacetoacetate, etc.

[0217] The aforementioned crosslinking agent (D) can be used alone or in combination of two or more kinds.

[0218] The content of the aforementioned crosslinking agent (D) is usually preferably 0.01 to 20 parts by mass, particularly preferably 0.2 to 10 parts by mass, and further preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the acrylic resin (A). If the crosslinking agent (D) is too little, there is a tendency for the cohesion of the adhesive to decrease, resulting in residual glue. If it is too much, there is a tendency for the flexibility and adhesiveness of the adhesive to decrease, and for lifting to occur between the reprocessed members.

[0219] [Photopolymerization initiator (E)]

[0220] This adhesive composition preferably contains a photopolymerization initiator (E).

[0221] The aforementioned photopolymerization initiator (E) may be any substance that generates free radicals under the action of light, and examples thereof include acetophenone compounds such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzil dimethyl ketal, 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl phenyl ketone, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-methyl-2-morpholinyl(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)butanone, 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone, 2-hydroxy-2-methyl-1-[4-(1-methylethenyl)phenyl]acetone oligomer, etc.;

[0222] benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, etc.;

[0223] benzophenone compounds such as benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyloxy)ethyl]benzylammonium bromide, (4-benzoylbenzyl)trimethylammonium chloride, etc.;

[0224] thioxanthone compounds such as 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one meso-chloride, etc.;

[0225] acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, etc. Among them, acylphosphine oxide compounds are preferred, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide is particularly preferred. It should be noted that these photopolymerization initiators (E) can be used alone or in combination of two or more.

[0226] In addition, as an auxiliary agent for these photoinitiators (E), for example, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler's ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethyl benzoate, ethyl 4-dimethylaminobenzoate, (n-butoxy)ethyl 4-dimethylaminobenzoate, isopentyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, etc. can be used in combination. These auxiliary agents can also be used alone or in combination of two or more kinds.

[0227] With respect to 100 parts by mass of the total of the acrylic resin (A) and the urethane (meth)acrylate-based compound (C) (when using an ethylenically unsaturated compound described later, it also includes the ethylenically unsaturated compound), the content of the aforementioned photoinitiator (E) is preferably 0.1 to 20 parts by mass, particularly preferably 0.5 to 15 parts by mass, and especially preferably 1 to 10 parts by mass. If the content of the photoinitiator (E) is too small, there is a tendency that the peelability after irradiation with active energy rays is likely to decrease, and if it is too large, there is a tendency that the contamination to the workpiece after irradiation with active energy rays becomes high.

[0228] 〔Antioxidant (F)〕

[0229] This adhesive composition preferably contains an antioxidant (F).

[0230] As the aforementioned antioxidant (F), for example, a primary antioxidant (F1) and a secondary antioxidant (F2) (excluding the antioxidant (F1)) can be cited, and it is preferable to use the primary antioxidant (F1) and the secondary antioxidant (F2) in combination. In addition, the antioxidant (F) can be in a solid state or in a liquid state.

[0231] As the aforementioned primary antioxidant (F1), for example, hindered phenol-based antioxidants and phenol-based antioxidants can be cited.

[0232] Specifically, as the aforementioned hindered phenol-based antioxidants, ADEKASTAB AO-20, ADEKASTAB AO-50, ADEKASTAB AO-60, ADEKASTAB AO-330 (all manufactured by ADEKA Corporation), etc. can be cited. In addition, IONOL, IONOL K98, IONOL 220 (manufactured by JAPAN CHEMTEC Corporation), etc. can be cited.

[0233] In addition, IRGANOX 1010, IRGANOX 1035, IRGANOX 1076, IRGANOX 1098, IRGANOX 1135, IRGANOX 1330, IRGANOX 1726, IRGANOX 1425WL, IRGANOX 1520L, IRGANOX 245, IRGANOX 259, IRGANOX 3114, IRGANOX 565 (manufactured by BASF JAPAN Co., Ltd.) and the like can be cited.

[0234] As the aforementioned phenolic antioxidant, specifically, Yoshinox BB, Yoshinox 425 (manufactured by Mitsubishi Chemical Corporation); ANTAGE DAH, ANTAGE DBH, ANTAGE W-300, ANTAGE W-400, ANTAGE W-500, ANTAGESP (manufactured by Kawaguchi Chemical Industry Co., Ltd.) and the like can be cited. In addition, ADEKASTAB AO-30, ADEKASTAB AO-40, ADEKASTAB AO-80 (all manufactured by ADEKA Corporation) and the like can be cited.

[0235] The content of the aforementioned primary antioxidant (F1) is usually 0.01 to 10 parts by mass, preferably 0.05 to 8 parts by mass, and more preferably 1 to 3 parts by mass with respect to 100 parts by mass of the acrylic resin (A). If the content of the primary antioxidant (F1) is too small, there is a tendency that the decrease in adhesion after irradiation with active energy rays after heating becomes insufficient. If the content of the primary antioxidant (F1) is too large, there is a tendency that it exudes to the adherend interface and the substrate interface, the adhesion to the adherend decreases, and the adhesion to the substrate interface deteriorates.

[0236] As the aforementioned secondary antioxidant (F2), sulfur-based antioxidants and phosphorus-based antioxidants can be cited.

[0237] As the aforementioned sulfur-based antioxidant, specifically, ADEKASTAB AO-412S, ADEKASTAB AO-513 (manufactured by ADEKA Corporation), Irganox PS 802FL (manufactured by BASF Corporation), Sumilizer MB (manufactured by Sumika Chemtex Corporation), DLTP “Yoshitomi” (dilauryl thiodipropionate), DSTP “Yoshitomi” (distearyl thiodipropionate), DMTP “Yoshitomi” (dimyristyl thiodipropionate) (manufactured by API Corporation) and the like can be cited.

[0238] Examples of the above-mentioned phosphorus-based antioxidants include phosphite-based antioxidants. Specifically, examples include IrgafoS 38, IrgafoS 126, IrgafoS 168 (all manufactured by BASF), SUMILIZER GP (manufactured by Sumitomo Chemical), ADEKASTAB PEP-8, ADEKASTAB PEP-36, ADEKASTAB HP-10, ADEKASTAB 2112, ADEKASTAB 1178, ADEKASTAB 1500, ADEKASTAB 135A, ADEKASTAB 3010, ADEKASTAB C, ADEKASTAB TPP (all manufactured by ADEKA), and the like.

[0239] The content of the secondary antioxidant (F2) is usually 0.1 to 2.0 parts by mass, preferably 0.2 to 1.5 parts by mass, and more preferably 0.5 to 1.25 parts by mass with respect to 100 parts by mass of the acrylic copolymer (A). If the content of the secondary antioxidant (F2) is too small, there is a tendency that the decrease in adhesion after irradiation with active energy rays after heating becomes insufficient. If the content of the secondary antioxidant is too large, there is a tendency to exude to the adherend interface or the substrate interface, resulting in a decrease in adhesion to the adherend and deterioration of the adhesion to the substrate interface.

[0240] When the above-mentioned primary antioxidant (F1) and secondary antioxidant (F2) are used in combination, the mass ratio [(F1) / (F2)] is usually 99 / 1 to 1 / 99, preferably 80 / 20 to 20 / 80, and more preferably 60 / 40 to 40 / 60.

[0241] Examples of other antioxidants include amine-based antioxidants and hindered amine-based antioxidants. They can be used alone or in combination of two or more.

[0242] 〔Other Components〕

[0243] From the viewpoint of peelability after irradiation with active energy rays, this adhesive composition also preferably further contains, within the range not impairing the effects of the present invention, for example, an ethylenically unsaturated compound. In addition, it may further contain additives such as antistatic agents, polymerization inhibitors, plasticizers, fillers, pigments, diluents, anti-aging agents, ultraviolet absorbers, ultraviolet stabilizers, and tackifying resins. These additives can be used alone or in combination of two or more. It should be noted that, in addition to the additives, impurities contained in the manufacturing raw materials of the components constituting this adhesive composition may be contained in a small amount.

[0244] As the aforementioned polymerization inhibitor, excluding nitroso compounds (B), examples thereof include dihydric phenols such as hydroquinone, catechol, and resorcinol; benzoquinones such as 1,4-benzoquinone; phenothiazine, copper dimethyldithiocarbamate, and the like. They can be used alone or in combination of two or more.

[0245] The content when compounding the aforementioned polymerization inhibitor is not particularly limited, and is preferably 0.01 to 5% by mass of this resin composition.

[0246] 〔Activation energy ray curable peelable adhesive composition〕

[0247] Thus, by mixing the acrylic resin (A), nitroso compound (B), preferably the urethane (meth)acrylate compound (C), crosslinking agent (D), photopolymerization initiator (E), antioxidant (F), and other components as needed, this adhesive composition is obtained.

[0248] The content of the acrylic resin (A) relative to the whole of this adhesive composition is usually 30% by mass or more, preferably 35% by mass or more, and particularly preferably 40% by mass or more.

[0249] In addition, when the aforementioned acrylic resin (A) is an acrylic resin (A1) having an ethylenically unsaturated group, the content of the acrylic resin (A) relative to the whole of this adhesive composition is usually 50% by mass or more, preferably 60% by mass or more, and particularly preferably 70% by mass or more. If the content of this acrylic resin (A) or the acrylic resin (A1) having an ethylenically unsaturated group is within the above range, the effects of the present invention are easily obtained.

[0250] This adhesive composition is usually preferably used as an adhesive sheet for temporarily protecting the surface of a workpiece such as an electronic substrate, semiconductor wafer, glass processed product, metal plate, or plastic plate during processing of the workpiece. The adhesive sheet has an adhesive layer obtained by crosslinking the aforementioned adhesive composition.

[0251] Hereinafter, the aforementioned adhesive sheet will be described.

[0252] 〔Adhesive sheet〕

[0253] The adhesive sheet according to an embodiment of the present invention (hereinafter sometimes referred to as "the present adhesive sheet") generally has a base sheet, an adhesive layer formed from the present adhesive composition, and a release film. As a method for producing the present adhesive sheet, first, the present adhesive composition is directly applied as it is onto the release film or the base sheet, or the concentration is adjusted using an appropriate organic solvent and then directly applied onto the release film or the base sheet. Thereafter, it is dried by, for example, heat treatment at 80 to 105 °C for 0.5 to 10 minutes, and adhered to the base sheet or the release film, thereby obtaining the present adhesive sheet. In addition, in order to present a balance in adhesive properties, it may be further cured after drying.

[0254] Examples of the aforementioned base sheet include a sheet formed from at least one synthetic resin selected from the group consisting of polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalic acid ethylene glycol copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyvinyl fluoride resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyvinyl fluoride; polyamides such as nylon 6 and nylon 6,6; vinyl polymers such as polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, and vinylon; cellulose resins such as triacetate cellulose and cellophane; acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, ethyl acrylate, and butyl acrylate; polystyrene; polycarbonate; polyarylate; and polyimide; metal foils of aluminum, copper, and iron; papers such as high-quality paper and cellophane; and fabrics and nonwoven fabrics formed from glass fibers, natural fibers, synthetic fibers, etc. These base sheets can be used in the form of a single layer or a multilayer in which two or more layers are laminated. Among these, from the viewpoint of weight reduction, etc., a sheet formed from a synthetic resin is preferred.

[0255] Furthermore, as the aforementioned release film, a release film obtained by subjecting various synthetic resin sheets, papers, fabrics, nonwoven fabrics, etc. exemplified in the aforementioned base sheet to a release treatment can be used.

[0256] In addition, as a method for applying the present adhesive composition, there is no particular limitation as long as it is a general application method, and examples thereof include methods such as roll coating, die coating, gravure coating, comma coating, and screen printing.

[0257] The thickness of the adhesive layer of the present adhesive sheet is generally preferably 3 to 200 μm, and more preferably 5 to 100 μm.

[0258] As the conditions for the aforementioned aging, the temperature is usually room temperature (23°C) to 70°C, and the time is usually 1 to 30 days. Specifically, for example, it can be carried out under conditions such as 1 to 20 days at 23°C, 3 to 10 days at 23°C, 1 to 7 days at 40°C, etc.

[0259] From the viewpoint of adhesiveness, the gel fraction of the adhesive layer of this adhesive sheet is preferably 10 to 99%, particularly preferably 20 to 97%, and further preferably 40 to 95%. If the gel fraction is too low, there is a tendency for the adhesive force to the processed member to decrease, and if it is too high, there is also a tendency for the adhesive force to the processed member to decrease.

[0260] The aforementioned gel fraction serves as a reference for the degree of crosslinking (degree of curing). For example, it is calculated by the following method. The adhesive sheet is pasted on a SUS mesh (200 mesh), wrapped, and immersed in a sealed container filled with ethyl acetate for 24 hours. Based on the mass change of the adhesive layer before and after the ethyl acetate immersion at this time, the gel fraction is obtained using the following formula.

[0261] Gel fraction (%) = mass of the adhesive layer after ethyl acetate immersion (g) / mass of the adhesive layer before ethyl acetate immersion (g) × 100

[0262] It should be noted that when adjusting the gel fraction of the adhesive layer to the aforementioned range, it is achieved by adjusting the type and amount of the crosslinking agent (D), etc.

[0263] By irradiating the adhesive layer of this adhesive sheet with active energy rays, the ethylenically unsaturated groups contained in the adhesive layer polymerize, the adhesive layer cures, and the adhesive force decreases, thereby enabling peeling.

[0264] As the active energy rays, usually in addition to using light such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, etc., electromagnetic waves such as X-rays and γ-rays, electron rays, proton rays, neutron rays, etc. can also be used, but from the viewpoints of curing speed, ease of obtaining an irradiation device, price, etc., ultraviolet rays are preferred.

[0265] The cumulative irradiation dose when irradiating the aforementioned ultraviolet rays is usually 50 to 3000 mJ / cm 2 and preferably 100 to 1000 mJ / cm 2 . In addition, the irradiation time also varies depending on the type of light source, the distance between the light source and the adhesive layer, the thickness of the adhesive layer, and other conditions. Usually, it can be several seconds, and in some cases, it can be a fraction of a second.

[0266] The adhesive force of this adhesive sheet also varies depending on the type of the base material sheet, the type of the member to be processed, etc. Before the irradiation with active energy rays, it is preferably 3.0 N / 25 mm or more, more preferably 4.0 N / 25 mm or more. It should be noted that the upper limit of the adhesive force before the irradiation with active energy rays is usually 100 N / 25 mm.

[0267] In addition, the adhesive force after the irradiation with active energy rays is preferably 0.5 N / 25 mm or less, more preferably 0.1 N / 25 mm or less.

[0268] In addition, when this adhesive sheet is heated at 175 °C for 1 hour and then irradiated with ultraviolet rays (cumulative irradiation dose: 250 mJ / cm 2 ), the adhesive force is preferably 1 N / 25 mm or less, more preferably 0.3 N / 25 mm or less.

[0269] Moreover, this adhesive sheet can be peeled off from the interface of the adherend without residue and paste residue after being heated at 180 °C for 1 hour. The adhesive force is preferably 3.0 N / 25 mm or more, more preferably 4.0 N / 25 mm or more. Further, when ultraviolet rays are irradiated thereafter (cumulative irradiation dose: 180 mJ / cm 2 ), the adhesive force is preferably less than 1.5 N / 25 mm, more preferably less than 1.0 N / 25 mm.

[0270] Furthermore, when this adhesive sheet is heated at 200 °C for 1 hour and then irradiated with ultraviolet rays (cumulative irradiation dose: 250 mJ / cm 2 ), the adhesive force is preferably 1 N / 25 mm or less, more preferably 0.4 N / 25 mm or less.

[0271] Regarding this adhesive composition, for example, after pasting the adhesive sheet obtained by using it as an adhesive layer to the member to be processed and temporarily protecting the surface of the member to be processed, active energy rays are irradiated. As a result, the adhesive layer is cured, the adhesive force is reduced, and it can be easily peeled off from the member to be processed, which is useful as a peelable adhesive sheet. In addition, the adhesive sheet of the present invention has excellent heat resistance. Therefore, after being pasted on the surface of the member to be processed, even when it is, for example, subjected to a heating process at 175 °C or higher, especially 200 °C or higher, the adhesive force is reduced by subsequent irradiation with active energy rays, and there is no residue of the adhesive, and excellent peelability is exhibited.

[0272] Examples

[0273] Hereinafter, examples are given to more specifically illustrate the present invention, but the present invention is not limited to the following examples as long as it does not exceed its gist.

[0274] It should be noted that hereinafter, “%” and “parts” mean mass basis.

[0275] [Manufacture of acrylic resin (A-1)]

[0276] 118 parts of ethyl acetate was charged into a four-necked round-bottom flask equipped with a reflux condenser, a stirrer, a nitrogen inlet, and a thermometer. The internal temperature was raised to the boiling point, and a mixed solution containing 54.8 parts of n-butyl acrylate (BA), 40 parts of methyl acrylate (MA), 5 parts of 2-hydroxyethyl acrylate (HEA), 0.2 parts of acrylic acid (Aac), and 0.056 parts of azobisisobutyronitrile (AIBN) as a polymerization initiator was added dropwise over 2 hours to cause a reaction. Then, after further reacting for 1 hour from the end of the dropwise addition, 4 parts of an ethyl acetate solution containing 0.037 parts of AIBN was added, and the reaction was carried out at the reflux temperature for 2 hours. After adding 4 parts of an ethyl acetate solution containing 0.026 parts of AIBN again and reacting at the reflux temperature for 2 hours, the reaction was stopped, and 40 parts of ethyl acetate was added for dilution to obtain an acrylic resin (A-1) solution. The copolymerization components, physical properties, etc. of the obtained acrylic resin (A-1) are shown in Table 1 described later.

[0277] [Manufacture of acrylic resin (A-2)]

[0278] 118 parts of ethyl acetate was charged into a four-necked round-bottom flask equipped with a reflux condenser, a stirrer, a nitrogen inlet, and a thermometer. The internal temperature was raised to the boiling point, and a mixed solution containing 58.8 parts of n-butyl acrylate (BA), 40 parts of methyl acrylate (MA), 1 part of 2-hydroxyethyl acrylate (HEA), 0.2 parts of N,N-dimethylaminoethyl acrylate (DMAEA), and 0.056 parts of azobisisobutyronitrile (AIBN) as a polymerization initiator was added dropwise over 2 hours to cause a reaction. Then, after further reacting for 1 hour from the end of the dropwise addition, 4 parts of an ethyl acetate solution containing 0.037 parts of AIBN was added, and the reaction was carried out at the reflux temperature for 2 hours. After adding 4 parts of an ethyl acetate solution containing 0.026 parts of AIBN again and reacting at the reflux temperature for 2 hours, the reaction was stopped, and 40 parts of ethyl acetate was added for dilution to obtain an acrylic resin (A-2) solution. The copolymerization components, physical properties, etc. of the obtained acrylic resin (A-2) are shown in Table 1 described later.

[0279] [Table 1]

[0280]

[0281] [Manufacture of acrylic resin (A1-1)]

[0282] Into a four-necked round-bottom flask equipped with a reflux condenser, a stirrer, a nitrogen inlet, and a thermometer, 65 parts of ethyl acetate was charged, and the internal temperature was raised to the boiling point. It took 2 hours to dropwise add a solution containing 70 parts of 2-ethylhexyl acrylate (2EHA), 10 parts of acryloylmorpholine (ACMO), 20 parts of 2-hydroxyethyl acrylate (HEA), and 0.045 parts of azobisisobutyronitrile (AIBN) as a polymerization initiator to cause a reaction. Then, 1 hour after the completion of the dropwise addition, 3 parts of 2-hydroxyethyl acrylate (HEA) and 7.5 parts of an ethyl acetate solution were added, and the reaction was carried out at the reflux temperature for 0.5 hour. Further, after adding 7.5 parts of an ethyl acetate solution containing 1% of AIBN, the reaction was carried out at the reflux temperature for 2 hours. Then, after adding 30 parts of an ethyl acetate solution containing 0.3% of AIBN again, the reaction was carried out at the reflux temperature for 2 hours, and then the reaction was stopped and diluted with ethyl acetate to obtain a solution of an acrylic resin (A3).

[0283] To the obtained solution of the acrylic resin (A3), 2-methacryloyloxyethyl isocyanate (MOI) and dibutyltin dilaurate as a urethanization catalyst were appropriately added, and the reaction was carried out at 50 °C for 18 hours. Then, 0.02 part of 4-methoxyphenol (MEHQ) was added to obtain a solution of an acrylic resin (A1-1) having an ethylenically unsaturated group (solid content: 45.9%, viscosity: 4900 mPa·s / 25 °C, acrylic resin (A1-1) having an ethylenically unsaturated group: weight average molecular weight (Mw) was 780,000, dispersity (Mw / Mn) was 5.5). The urethanization rate of HEA based on MOI was 90 mol%, and the content of the ethylenically unsaturated group was 125 mmol / 100 g. The copolymerization composition, physical properties, etc. of the obtained acrylic resin (A1-1) having an ethylenically unsaturated group are shown in Table 2 below.

[0284] 〔Production of acrylic resin (A1-2)〕

[0285] Into a four-necked round-bottom flask equipped with a reflux condenser, a stirrer, a nitrogen inlet, and a thermometer, 8 parts of ethyl acetate, 23 parts of acetone, 40 parts of 2-ethylhexyl acrylate (2EHA), 20 parts of 2-hydroxyethyl acrylate (HEA), and 0.1 part of bis[4-(methoxycarbonyl)benzyl] trithiocarbonate were charged. After raising the internal temperature to the boiling point, 8 parts of an ethyl acetate solution containing 0.14% of azobisisobutyronitrile (AIBN) as a polymerization initiator were added dropwise over 30 minutes. Then, after reacting at the reflux temperature for 2 hours, 5 parts of an ethyl acetate solution containing 0.2% of AIBN were added, and the reaction was carried out at the reflux temperature for 3 hours. Further, after adding 5 parts of an ethyl acetate solution containing 0.2% of AIBN, the reaction was carried out at the reflux temperature for 2 hours, and then the reaction was stopped and diluted with ethyl acetate to obtain an acrylic resin solution having a polymer segment (Y)-(Y).

[0286] The acrylic resin having a polymer segment (Y)-(Y) obtained in the previous step and 30 parts of 2-ethylhexyl acrylate (2EHA) and 10 parts of acryloylmorpholine (ACMO) were charged. After raising the internal temperature to the boiling point, 8 parts of an ethyl acetate solution containing 0.14% of azobisisobutyronitrile (AIBN) as a polymerization initiator were added dropwise over 30 minutes. Then, after reacting at the reflux temperature for 2 hours, 5 parts of an ethyl acetate solution containing 0.2% of AIBN were added, and the reaction was carried out at the reflux temperature for 3 hours. Further, after adding 5 parts of an ethyl acetate solution containing 1% of AIBN, the reaction was carried out at the reflux temperature for 2 hours, and then the reaction was stopped and diluted with ethyl acetate to obtain an acrylic resin (A4) solution having a polymer segment (Y)-(Z)-(Y).

[0287] To the acrylic resin (A4) solution obtained above, 2-methacryloyloxyethyl isocyanate (hereinafter referred to as "MOI") (manufactured by Showa Denko K.K.) and dibutyltin dilaurate as a urethanization catalyst were appropriately added, and the reaction was carried out at 50 °C for 18 hours. Then, 0.02 part of MEHQ was added to obtain an acrylic resin (A1-2) solution containing an ethylenically unsaturated group (solid content: 47.5%, viscosity: 1000 mPa·s / 25 °C, acrylic resin (A1-2): weight average molecular weight (Mw) = 380,000, dispersity (Mw / Mn) = 2.9). The urethanization rate of HEA based on MOI was 90 mol%, and the content of the ethylenically unsaturated group was 125 mmol / 100 g. The copolymerization composition, physical properties, etc. of the obtained acrylic resin (A1-2) having an ethylenically unsaturated group are shown in Table 2 below.

[0288] [Manufacture of acrylic resin (A1-3)]

[0289] Into a four-necked round-bottomed flask equipped with a reflux condenser, a stirrer, a nitrogen inlet, and a thermometer, 30 parts of ethyl acetate, 23 parts of acetone, 70 parts of 2-ethylhexyl acrylate (2EHA), 10 parts of acryloylmorpholine (ACMO), 20 parts of 2-hydroxyethyl acrylate (HEA), and 0.05 part of 3-((((1-carboxyethyl)thio)thiocarbonyl)thio)propionic acid were charged. After raising the internal temperature to the boiling point, 10 parts of an ethyl acetate solution containing 0.1% of azobisisobutyronitrile (AIBN) as a polymerization initiator was added dropwise over 30 minutes. Then, after reacting at the reflux temperature for 2 hours, 10 parts of an ethyl acetate solution containing 0.1% of AIBN was added, and the reaction was carried out at the reflux temperature for 3 hours. Further, after adding 10 parts of an ethyl acetate solution containing 0.1% of AIBN, the reaction was carried out at the reflux temperature for 2 hours, and then the reaction was stopped and diluted with ethyl acetate to obtain a solution of an acrylic resin (A5).

[0290] To the solution of the acrylic resin (A5) obtained above, 2-methacryloyloxyethyl isocyanate (hereinafter referred to as "MOI") (manufactured by Showa Denko K.K.) and dibutyltin dilaurate as a urethanization catalyst were appropriately added, and after reacting at 50 °C for 18 hours, 0.02 part of MEHQ was added to obtain a solution of an acrylic resin (A1-3) containing an ethylenically unsaturated group (solid content: 50.4%, viscosity: 3900 mPa·s / 25 °C, acrylic resin (A1-3): weight average molecular weight (Mw) of 840,000, dispersity (Mw / Mn) of 3.2). The urethanization rate of HEA based on MOI was 90 mol%, and the content of the ethylenically unsaturated group was 125 mmol / 100 g. The copolymerization composition, physical properties, etc. of the obtained acrylic resin (A1-3) having an ethylenically unsaturated group are shown in Table 2 below.

[0291] [Table 2]

[0292]

[0293] 〔Nitroso compound (B)〕

[0294] As the nitroso compound (B), the following compounds were prepared.

[0295] ·Q1301 (B-1): Aluminum N-nitrosophenylhydroxylamine salt, manufactured by Fujifilm Wako Pure Chemical Corporation

[0296] 〔Polymerization inhibitor other than nitroso compound〕

[0297] ·MEHQ (B'-1): 4-Methoxyphenol, manufactured by Kishida Chemical Co., Ltd.

[0298] ·BHT (B'-2): Dibutylhydroxytoluene, manufactured by Kishida Chemical Co., Ltd.

[0299] Manufacture of urethane (meth) acrylate compound (C-1)

[0300] Into a four-necked flask equipped with a temperature regulator, thermometer, stirrer, water condenser, and nitrogen inlet, 6.6 g of isophorone diisocyanate (isocyanate group content: 37.8%), 93.4 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (hydroxyl value: 48 mgKOH / g), 0.06 g of 2,6-di-tert-butyl-p-cresol as a polymerization inhibitor, and 0.02 g of dibutyltin dilaurate as a reaction catalyst were charged, and the reaction was carried out at 60 °C. The reaction was terminated when the residual isocyanate group became 0.3% or less, and a urethane acrylate compound (C-1) (number of ethylenically unsaturated groups: 10, weight-average molecular weight: 2000, acryloyl concentration: 5.0 mmol / g) was obtained.

[0301] Manufacture of urethane (meth) acrylate compound (C-2)

[0302] Into a four-necked flask equipped with a temperature regulator, thermometer, stirrer, water condenser, and nitrogen inlet, 18.3 parts of isophorone diisocyanate (isocyanate group content: 37.8%), 81.7 parts of a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (hydroxyl value: 119.1 mgKOH / g), 0.04 part of 2,6-di-tert-butyl-p-cresol as a polymerization inhibitor, and 0.02 part of dibutyltin dilaurate as a reaction catalyst and belonging to tin compounds were charged, and the reaction was carried out at 60 °C. The reaction was terminated when the residual isocyanate group became 0.3% or less, and a urethane acrylate compound (C-2) (number of ethylenically unsaturated groups: 6, weight-average molecular weight: 1300, acryloyl concentration: 25.4 mmol / g) was obtained.

[0303] Crosslinking agent (D)

[0304] As the crosslinking agent (D), the following crosslinking agent was prepared.

[0305] · Crosslinking agent (D-1): TAKENATE D101E (adduct of tolylene diisocyanate and trimethylolpropane, manufactured by Mitsui Chemicals, Inc.)

[0306] Photoinitiator (E)

[0307] As the photoinitiator (E), the following photoinitiator was prepared.

[0308] · Photoinitiator (E-1): Omnirad 819 (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, manufactured by IGM Resins B.V.)

[0309] · Photoinitiator (E-2): Omnirad 127 (2-hydroxy-1-(4-(2-hydroxy-2-methylpropanoyl)benzyl)phenyl)-2-methylpropan-1-one, manufactured by IGM Resins B.V.)

[0310] [Antioxidant (F)]

[0311] As the primary antioxidant (F1), the following primary antioxidants were prepared.

[0312] · Primary antioxidant (F1-1): Irganox 1010 (pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), manufactured by BASF JAPAN)

[0313] · Primary antioxidant (F1-2): Yoshinox BB ((2,2'-methylenebis-6-tert-butyl-4-ethylphenol), manufactured by Mitsubishi Chemical Corporation)

[0314] As the secondary antioxidant (F2), the following secondary antioxidants were prepared.

[0315] · Secondary antioxidant (F2-1): Irgafos 168 (tris(2,4-di-tert-butylphenyl)phosphite, manufactured by BASF JAPAN)

[0316] · Secondary antioxidant (F2-2): DLTP "Yoshitomi" (dilauryl thiodipropionate, manufactured by API Corporation)

[0317] [Examples 1 to 10, Comparative Examples 1 to 6]

[0318] With respect to 100 parts of the acrylic resin (A) prepared and prepared as described above, the following were added and mixed as shown in Table 3 below: nitroso compound (B), urethane (meth)acrylate-based compound (C), crosslinking agent (D), photoinitiator (E), and the solid content concentration (resin component) was adjusted to 30% by mass with ethyl acetate to obtain the active energy ray-curable pressure-sensitive adhesive composition solutions of Examples 1 to 10 and Comparative Examples 1 to 6.

[0319] [Table 3]

[0320]

[0321] [Manufacture of Adhesive Sheet (S1)]

[0322] The active energy ray-curable peelable adhesive composition solutions of Examples 1 to 10 and Comparative Examples 1 to 6 obtained above were coated on a polyester film (film thickness: 50 μm) [manufactured by Toray Industries, Inc.: Lumirror (registered trademark) X10S] so that the dried thickness became 25 μm. After drying at 100°C for 5 minutes, it was pasted onto a lightly peeling 38-μm polyester release film (manufactured by Mitsui Chemicals Tohcello, Inc.: Separator SP-PET (registered trademark) SP01-38BU), and cured in an environment at 40°C for 3 days to obtain an adhesive sheet (S1).

[0323] Using the obtained adhesive sheet (S1), the gel fraction and adhesive strength were measured and evaluated by the methods shown below. The evaluation results are shown in Table 4.

[0324] [Gel fraction]

[0325] After cutting the above-mentioned adhesive sheet (S1) into 40 mm × 40 mm, the lightly peeling 38-μm polyester release film was peeled off, and the adhesive layer side was pasted onto a 50 mm × 100 mm SUS mesh sheet (200 mesh). With respect to the length direction of the SUS mesh sheet, the sample was folded back from the central part to wrap it. It was immersed in a sealed container containing 250 g of ethyl acetate for 24 hours, and the gel fraction was calculated using the following formula based on the mass change of the adhesive layer before and after the ethyl acetate immersion.

[0326] Gel fraction (%) = (mass of the adhesive sheet after ethyl acetate immersion (g) - X

[0327] / mass of the adhesive sheet before ethyl acetate immersion (g) - X) × 100

[0328] X = average value (g) of the mass of 7 pieces of 40 mm × 40 mm cut from the polyester film (film thickness: 50 μm) [manufactured by Toray Industries, Inc.: Lumirror (registered trademark) X10S]

[0329] [Adhesive strength at 23°C before active energy ray irradiation]

[0330] A test piece of 25 mm × 100 mm was prepared from the above-mentioned adhesive sheet (S1), the lightly peeling 38-μm polyester release film was peeled off, and it was pressure-bonded to a sodium glass plate (manufactured by JAPAN TEST PANEL) by reciprocating a 2-kg rubber roller twice in an atmosphere at 23°C and 50% RH. After standing in the same atmosphere for 30 minutes, the 180-degree peel strength (N / 25 mm) was measured at a peel speed of 300 mm / min, and the evaluation was carried out according to the following criteria.

[0331] [Evaluation criteria]

[0332] ○(Very good): 10 N / 25 mm or more

[0333] ×(Poor): Less than 10 N / 25 mm

[0334] [Adhesive strength after heating at 180 °C and irradiation with active energy rays]

[0335] A test piece of 25 mm × 100 mm is made from the aforementioned adhesive sheet (S1), the lightly peeled 38-μm polyester release sheet is peeled off, and it is pressure-bonded to a sodium glass plate (manufactured by JAPAN TEST PANEL CO., LTD.) by reciprocating a 2-kg rubber roller twice in an atmosphere of 23 °C and 50% RH. Thereafter, heat treatment is performed at 180 °C for 1 hour. After allowing the sodium glass plate with the heat-treated adhesive sheet pasted thereon to stand for 1 hour in an atmosphere of 23 °C and a relative humidity of 50%, ultraviolet irradiation is performed from the polyester sheet side using one 80-W high-pressure mercury lamp (cumulative irradiation dose is 180 mJ / cm 2 ), and after allowing it to stand for 30 minutes in an atmosphere of 23 °C and 50% RH, the 180-degree peel strength (N / 25 mm) is measured at a peel speed of 300 mm / min. In addition, the peel state is visually observed and evaluated according to the following criteria respectively.

[0336] [Evaluation criteria]

[0337] (Adhesive strength)

[0338] ◎(Perfect): Less than 1 N / 25 mm

[0339] ○(Very good): 1 N / 25 mm or more and less than 1.5 N / 25 mm

[0340] ×(Poor): 1.5 N / 25 mm or more

[0341] (Peel state)

[0342] 〇(Very good): No residual adhesive

[0343] △(Good): Residual adhesive remains

[0344] ×(Poor): Residual adhesive remains, material damage occurs, and interfacial peeling on the substrate side occurs

[0345] [Table 4]

[0346]

[0347] Based on the results of Table 4 above, the adhesive sheets manufactured using the active energy ray-curable peelable adhesive compositions of Examples 1 to 10 had good adhesive force before active energy ray irradiation. Further, when heated at 180°C and then irradiated with active energy rays, the adhesive force decreased, and the peeling state also showed peeling at the interface on the adherend side with little residual adhesive.

[0348] On the other hand, the adhesive sheets manufactured using the active energy ray-curable peelable adhesive compositions of Comparative Examples 1 to 6 without nitroso compound (B) did not satisfy the adhesive properties before and after active energy ray irradiation at all.

[0349] <Examples 11 to 21, Comparative Examples 7 to 17>

[0350] To 100 parts of the acrylic resin (A1) prepared and prepared as above, the following were added and mixed as shown in Tables 5 and 6 below: nitroso compound (B), crosslinking agent (D), photopolymerization initiator (E), antioxidant (F), and the solid content concentration (resin component) was adjusted to 30% by mass using ethyl acetate to obtain an adhesive composition solution.

[0351] [Table 5]

[0352]

[0353] [Table 6]

[0354]

[0355] Using the active energy ray-curable peelable adhesive composition solutions of Examples 11 to 21 and Comparative Examples 7 to 15 obtained above, adhesive sheets were produced as follows.

[0356] <Manufacture of Adhesive Sheet (S2)>

[0357] The active energy ray-curable peelable adhesive composition solutions of Examples 11 to 21 and Comparative Examples 7 to 15 obtained above were coated on a 38-μm heavy-release polyester release sheet (manufactured by Mitsui Chemicals Tohcello, Inc.: Lumirror (registered trademark) SP03-38BU) so that the dried thickness became 25 μm, dried at 100°C for 5 minutes, and then pasted on a 38-μm light-release polyester release sheet (manufactured by Mitsui Chemicals Tohcello, Inc.: Lumirror (registered trademark) SP01-38BU), and cured for 3 days in an environment at 40°C to obtain an adhesive sheet (S2).

[0358] <Manufacture of Adhesive Sheet (S3)>

[0359] The radiation-curable release pressure-sensitive adhesive composition solutions of Examples 11 to 21 and Comparative Examples 7 to 17 obtained above were applied to a polyimide film (film thickness: 50 μm) (manufactured by Toray DuPont Co., Ltd.: KAPTON 200H) so that the dried thickness became 25 μm. After drying at 100°C for 5 minutes, it was adhered to a lightly releasable 38-μm polyester release sheet (manufactured by Mitsui Chemicals Tohcello, Inc.: Lumirror (registered trademark) SP01-38BU), and cured at 40°C for 3 days to obtain an adhesive sheet (S3).

[0360] Using the obtained adhesive sheets (S2) and (S3), the gel fraction and adhesive strength were measured and evaluated by the methods shown below. The evaluation results are shown in Tables 7 to 10.

[0361] [Gel fraction]

[0362] After cutting the above-mentioned adhesive sheet (S2) into 40 mm × 40 mm, the 38-μm polyester release sheet with light release was peeled off, and the adhesive layer side was adhered to a 50 mm × 100 mm SUS mesh sheet (200 mesh). Then, the 38-μm polyester release sheet with heavy release was peeled off, and the sample was folded back and wrapped from the central part with respect to the length direction of the SUS mesh sheet. It was immersed in a sealed container containing 250 g of ethyl acetate for 24 hours, and the gel fraction was calculated using the following formula based on the mass change of the adhesive layer before and after the ethyl acetate immersion.

[0363] Gel fraction (%) = (mass of the adhesive layer after ethyl acetate immersion (g)

[0364] / mass of the adhesive layer before ethyl acetate immersion (g)) × 100

[0365] [Adhesive strength at 23°C before active energy ray irradiation]

[0366] A 25 mm × 100 mm test piece was prepared from the above-mentioned adhesive sheet (S3), the 38-μm polyester release sheet with light release was peeled off, and it was pressure-bonded to an alkali-free glass plate (manufactured by Corning, Inc., EAGLE XG) by reciprocating a rubber roller with a mass of 2 kg twice at 23°C and 50% RH. After standing for 30 minutes in the same atmosphere, the 180-degree peel strength (N / 25 mm) was measured at a peel speed of 300 mm / min.

[0367] [Adhesive strength at 23°C after active energy ray irradiation]

[0368] A test piece of 25 mm × 100 mm was made from the aforementioned adhesive sheet (S3). The lightly peeled 38-μm polyester release sheet was peeled off, and a rubber roller with a mass of 2 kg was reciprocated twice under an atmosphere of 23°C and 50% RH to be pressure-bonded to an alkali-free glass plate (manufactured by Corning Inc., EAGLE XG), and then left standing for 30 minutes under the same atmosphere. Thereafter, ultraviolet irradiation was performed from the side of the alkali-free glass plate using one 80-W high-pressure mercury lamp (the cumulative irradiation dose was 250 mJ / cm 2 ), and after leaving standing for 30 minutes under an atmosphere of 23°C and 50% RH, the 180-degree peel strength (N / 25 mm) was measured at a peel speed of 300 mm / min.

[0369] [Adhesion force after heating at 175°C and before active energy ray irradiation]

[0370] A test piece of 25 mm × 100 mm was made from the aforementioned adhesive sheet (S3). The lightly peeled 38-μm polyester release sheet was peeled off, and a rubber roller with a mass of 2 kg was reciprocated twice under an atmosphere of 23°C and 50% RH to be pressure-bonded to an alkali-free glass plate (manufactured by Corning Inc., EAGLE XG). Thereafter, heat treatment was performed at 175°C for 1 hour. After leaving the stainless steel plate with the adhesive sheet after the heat treatment standing for 1 hour under an atmosphere of 23°C and a relative humidity of 50%, the 180-degree peel strength (N / 25 mm) was measured at a peel speed of 300 mm / min and evaluated according to the following criteria.

[0371] [Evaluation criteria]

[0372] 〇(Very good) ··· 4 N / 25 mm or more

[0373] ×(Poor) ··· Less than 4 N / 25 mm

[0374] [Adhesion force after heating at 175°C and after active energy ray irradiation]

[0375] A test piece of 25 mm × 100 mm was made from the aforementioned adhesive sheet (S3). The lightly peeled 38-μm polyester release sheet was peeled off, and a rubber roller with a mass of 2 kg was reciprocated twice under an atmosphere of 23°C and 50% RH to be pressure-bonded to an alkali-free glass plate (manufactured by Corning Inc., EAGLE XG). Thereafter, heat treatment was performed at 175°C for 1 hour. After leaving the stainless steel plate with the adhesive sheet after the heat treatment standing for 1 hour under an atmosphere of 23°C and a relative humidity of 50%, ultraviolet irradiation was performed from the side of the alkali-free glass plate using one 80-W high-pressure mercury lamp (the cumulative irradiation dose was 250 mJ / cm 2 ), and after leaving standing for 30 minutes under an atmosphere of 23°C and 50% RH, the 180-degree peel strength (N / 25 mm) was measured at a peel speed of 300 mm / min and evaluated according to the following criteria.

[0376] [Evaluation Criteria]

[0377] 〇(Very Good) ··· Below 0.3 N / 25 mm

[0378] ×(Poor) ··· Greater than 0.3 N / 25 mm

[0379] [Table 7]

[0380]

[0381] [Table 8]

[0382]

[0383] [Adhesion after Heating at 200°C and before Active Energy Ray Irradiation]

[0384] Prepare a test piece of 25 mm × 100 mm from the aforementioned adhesive sheet (S2), peel off the lightly peeled 38-μm polyester release sheet, and press and paste it onto an alkali-free glass plate (manufactured by Corning Inc., EAGLE XG) by reciprocating a 2-kg rubber roller twice in an atmosphere of 23°C and 50% RH. Then, perform a heat treatment at 200°C for 1 hour. After leaving the stainless steel plate with the heat-treated adhesive sheet pasted thereon to stand in an atmosphere of 23°C and a relative humidity of 50% for 1 hour, measure the 180-degree peel strength (N / 25 mm) at a peel speed of 300 mm / min and evaluate it according to the following criteria.

[0385] [Evaluation Criteria]

[0386] 〇(Very Good) ··· 3 N / 25 mm or more

[0387] ×(Poor) ··· Less than 3 N / 25 mm

[0388] [Adhesion after Heating at 200°C and after Active Energy Ray Irradiation]

[0389] Prepare a test piece of 25 mm × 100 mm from the aforementioned adhesive sheet (S2), peel off the lightly peeled 38-μm polyester release sheet, and press and paste it onto an alkali-free glass plate (manufactured by Corning Inc., EAGLE XG) by reciprocating a 2-kg rubber roller twice in an atmosphere of 23°C and 50% RH. Then, perform a heat treatment at 200°C for 1 hour. After leaving the stainless steel plate with the heat-treated adhesive sheet pasted thereon to stand in an atmosphere of 23°C and a relative humidity of 50% for 1 hour, use one 80-W high-pressure mercury lamp to perform ultraviolet irradiation from the side of the alkali-free glass plate (the cumulative irradiation dose is 250 mJ / cm 2) After standing still for 30 minutes in an atmosphere of 23°C and 50% RH, the 180-degree peel strength (N / 25 mm) was measured at a peel rate of 300 mm / min. In addition, the peel state was observed visually and evaluated according to the following criteria respectively.

[0390] [Evaluation Criteria]

[0391] (Adhesion)

[0392] ◎(Perfect) ·· Less than 0.4 N / 25 mm

[0393] 〇(Very Good) ·· 0.4 N / 25 mm or more and less than 0.6 N / 25 mm

[0394] ×(Poor) ·· 0.6 N / 25 mm or more

[0395] (Peel State)

[0396] 〇(Very Good) ·· No residual adhesive

[0397] △(Good) ·· There is residual adhesive

[0398] ×(Poor) ·· There is residual adhesive, material damage occurs, and interfacial peeling on the substrate side

[0399] [Table 9]

[0400]

[0401] [Table 10]

[0402]

[0403] According to the results of the aforementioned Tables 7 to 10, the adhesive sheets manufactured using the active energy ray-curable peelable adhesive compositions of Examples 11 to 21 have sufficient adhesion before active energy ray irradiation, excellent heat resistance, and even when exposed to high temperatures, after active energy ray irradiation, the adhesion decreases, there is no residual adhesive, and it has the excellent effect of peelability.

[0404] In contrast, the decrease in adhesion after active energy ray irradiation of the adhesive sheets manufactured using the active energy ray-curable peelable adhesive compositions of Comparative Examples 7 to 17 is insufficient after exposure to high temperatures.

[0405] From this, it can be known that in order to have sufficient adhesion before active energy ray irradiation and also cause the adhesion after active energy ray irradiation to decrease after exposure to high temperatures, it is important to contain a specific amount of nitroso compound.

[0406] In the foregoing embodiments, specific modes in the present invention are shown, but the foregoing embodiments are merely illustrative examples and are not to be construed in a limiting sense. It should be considered that various modifications obvious to those skilled in the art fall within the scope of the present invention.

[0407] Industrial Applicability

[0408] The adhesive composition of the present invention can be suitably used for an adhesive sheet for temporary surface protection when processing an electronic substrate, a semiconductor wafer, a glass processed product, a metal plate, a plastic plate, etc.

Claims

1. A curable energy ray-curable release-type adhesive composition containing an acrylic resin (A) and a nitroso compound (B), wherein the content of the nitroso compound (B) is 0.01 to 1 part by mass with respect to 100 parts by mass of the acrylic resin (A).

2. The active energy ray-curable release type adhesive composition according to claim 1, wherein, The acrylic resin (A) has a structural unit derived from an alkyl (meth)acrylate (a1).

3. The active energy ray-curable peelable adhesive composition according to claim 1, wherein, The acrylic resin (A) has a structural unit derived from a functional group-containing monomer (a2).

4. The active energy ray-curable release type adhesive composition according to claim 1, wherein, The acrylic resin (A) has a structural unit derived from a hydroxyl group-containing monomer (a2-1).

5. The curable energy ray-curable pressure-sensitive adhesive composition according to claim 4, wherein, The content of the structural unit derived from the hydroxyl group-containing monomer (a2-1) is 0.1 to 10% by mass of all the structural units of the acrylic resin (A).

6. The active energy ray-curable peelable adhesive composition according to claim 1, wherein, The acrylic resin (A) has a structural unit derived from a carboxyl group-containing monomer (a2-2).

7. The active energy ray-curable peelable adhesive composition according to claim 6, wherein, The content of the structural unit derived from the carboxyl group-containing monomer (a2-2) is 0.01 to 10% by mass of all the structural units of the acrylic resin (A).

8. The active energy ray-curable peelable adhesive composition according to claim 1, wherein, The acrylic resin (A) is an acrylic resin (A1) having an ethylenically unsaturated group.

9. The active energy ray-curable peelable adhesive composition according to claim 8, wherein, The content of the ethylenically unsaturated group in the acrylic resin (A1) having an ethylenically unsaturated group is 5 to 250 mmol / 100 g.

10. The curable energy ray-curable release-type adhesive composition according to claim 1, further containing a urethane (meth)acrylate compound (C).

11. The active energy ray-curable peelable adhesive composition according to claim 10, wherein, The urethane (meth)acrylate compound (C) has an ethylenically unsaturated group, and the number of the ethylenically unsaturated groups is 5 to 20.

12. The active energy ray-curable peelable adhesive composition according to claim 10, wherein, The urethane (meth)acrylate compound (C) is a reaction product of a hydroxyl group-containing (meth)acrylate compound and a polyisocyanate compound (c2), and the hydroxyl group-containing (meth)acrylate compound contains 3 or more ethylenically unsaturated groups in the molecule.

13. The active energy ray-curable peelable adhesive composition according to claim 1, wherein, The nitroso compound (B) is ammonium N-nitrosophenylhydroxylamine and / or aluminum N-nitrosophenylhydroxylamine.

14. The curable energy ray-curable release-type adhesive composition according to claim 1, further containing a crosslinking agent (D).

15. The curable energy ray-curable release-type adhesive composition according to claim 1, further containing a photopolymerization initiator (E).

16. An adhesive sheet having an adhesive layer obtained by crosslinking the adhesive composition according to any one of claims 1 to 15.

17. The adhesive sheet according to claim 16, wherein, By irradiation with curable energy rays, the adhesive layer is cured and can be peeled off.

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