JP2022023819A - Active energy ray-curable peelable adhesive composition, active energy ray-curable peelable adhesive sheet and active energy ray-curable peelable adhesive - Google Patents

Abstract

To provide an adhesive composition that has favorable peelability (light adhesion) after active energy ray irradiation and can form an adhesive layer having high elongation at break.SOLUTION: An active energy ray-curable peelable adhesive composition contains an ethylenically unsaturated group-containing acrylic resin (A) having an ethylenically unsaturated group-containing structural site (α) with a number average molecular weight of 1000-300,000 in a side chain.SELECTED DRAWING: None

Description

The present invention is an active energy ray-curable release type pressure-sensitive adhesive composition containing an ethylenically unsaturated group-containing acrylic resin having an ethylenically unsaturated group-containing structural portion in a side chain, and an active energy ray-curable adhesive composition using the same. Regarding peelable adhesive sheets and active energy ray-curable peelable adhesives, in particular, dying and backgrinding processes for temporary surface protection adhesive sheets for substrates such as metal plates and plastic plates, and semiconductor devices such as semiconductor wafers. The present invention relates to an active energy ray-curable release type pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, and a pressure-sensitive adhesive, which are useful as pressure-sensitive adhesive sheets for fixing semiconductors used in semiconductor manufacturing processes such as.

The active energy ray-curable resin composition, which is cured by irradiating with active energy rays such as ultraviolet rays and electron beams, is used for applications such as adhesives, adhesives, paints, inks, coating materials, and optical molding materials. ..

Further, the active energy ray-curable resin composition temporarily forms the surface of the material to be processed for the purpose of preventing stains and damage to the material to be processed in processing such as drilling holes in a substrate such as a metal plate or a plastic plate. Also used as an adhesive layer in a surface-protecting adhesive sheet for protecting Be done. In the following, the member to be processed including the substrate and the semiconductor device is also referred to as a "processed member", and is collectively referred to as an "adhesive sheet" including the surface protection adhesive sheet and the semiconductor fixing adhesive sheet.

The above-mentioned adhesive sheet is required to have an appropriate adhesive force with respect to the member to be processed due to the recent miniaturization of processing technology and the thinning of the member to be processed. Since it is necessary to peel off the adhesive sheet after that, it is required that the adhesive sheet can be peeled off without adhesive residue with a light force after irradiation with active energy rays.

In such an active energy ray-curable resin composition, for example, at least one of a monomer and an oligomer having an ethylenically unsaturated group and an acrylic resin may be blended, or the acrylic resin itself may contain an ethylenically unsaturated group. By doing so, the active energy ray curability is exhibited. Among them, the ethylenically unsaturated group-containing acrylic resin in which the acrylic resin itself contains an ethylenically unsaturated group has a small amount of low molecular weight components even after being cured by irradiation with active energy rays, and therefore, the adhesive residue after peeling. It is advantageous for reduction.

As a pressure-sensitive adhesive sheet used in the dicing process of a semiconductor wafer, for example, Patent Document 1 describes a pressure-sensitive adhesive composed of a pressure-sensitive adhesive and a radiation-polymerizable compound which is a urethane acrylate-based oligomer having a molecular weight of 3000 to 10,000 on the substrate surface. A pressure-sensitive adhesive sheet coated with a layer is disclosed, and it is described that the adhesive strength between the wafer chip and the pressure-sensitive adhesive sheet is reduced after irradiation, and the wafer chip can be easily picked up.

Further, in Patent Document 2, for example, 2-hydroxyethyl acrylate is copolymerized as a pressure-sensitive adhesive composition using an ethylenically unsaturated group-containing acrylic resin in which the acrylic resin itself contains an ethylenically unsaturated group. Described is a re-peelable pressure-sensitive adhesive using an acrylic resin containing an ethylenically unsaturated group by subjecting 2-methacryloyloxyethyl isocyanate to a urethanization reaction with the acrylic polymer.

Japanese Unexamined Patent Publication No. 62-153376 Japanese Unexamined Patent Publication No. 2010-53346

However, in the technique disclosed in Patent Document 1, although the adhesive strength of the peelable adhesive after curing is reduced, the adhesive remains on the wafer chip during peeling, the wafer chip scatters during dicing, and the wafer is expanded. There is a problem that the chip peels off and falls off, and further improvement is required.

Further, the technique disclosed in Patent Document 2 has good peelability after curing by ultraviolet irradiation, but the adhesive after curing tends to be hard, so that the elongation of the adhesive layer is reduced and expansion is difficult. become.

In recent years, there has been a growing demand for stain resistance such as not leaving adhesive residue on the member to be processed in peeling after curing by ultraviolet irradiation, and in order to improve such stain resistance, a pressure-sensitive adhesive after curing has been required. The elongation of the layer is important, and it is desired that the adhesive layer has a high breaking elongation.

Therefore, in the present invention, under such a background, a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having excellent peelability (slight adhesiveness) after irradiation with active energy rays and having a high elongation at break is provided. The purpose is to provide.

However, in the active energy ray-curable release type pressure-sensitive adhesive composition containing an ethylenically unsaturated group-containing acrylic resin, the present inventor has a relatively high molecular weight ethylenically unsaturated on the side chain of the acrylic resin. The present invention has been completed by finding that a pressure-sensitive adhesive layer having excellent peelability (slight adhesiveness) after irradiation with active energy rays and having high breaking elongation can be formed by containing a group-containing structural portion.

That is, the present invention contains an ethylenically unsaturated group-containing acrylic resin (A) having an ethylenically unsaturated group-containing structural site (α) having a number average molecular weight of 1,000 to 300,000 in the side chain. The first gist is a release-type pressure-sensitive adhesive composition.

The second gist of the present invention is an active energy ray-curable release type pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on which the active energy ray-curable release type pressure-sensitive adhesive composition of the first gist is crosslinked.

Further, the present invention is a pressure-sensitive adhesive in which an active energy ray-curable release type pressure-sensitive adhesive composition containing an ethylenically unsaturated group-containing acrylic resin, a cross-linking agent (B) and a photopolymerization initiator (C) is cross-linked. Therefore, the active energy ray-curable release type adhesive that satisfies the following requirement [I] is the third gist.
[I] The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet having a cross-linked pressure-sensitive adhesive layer having a thickness of 300 μm was irradiated with ultraviolet rays having a cumulative irradiation amount of 1000 mJ / cm ² using one 80 W high-pressure mercury lamp. After allowing to stand for 30 minutes in an atmosphere of ° C. and 50% RH, the elongation at break measured by a tensile tester at a tensile speed of 300 mm / min is 90 to 300%.

According to the active energy ray-curable release type pressure-sensitive adhesive composition of the present invention, it is possible to form a pressure-sensitive adhesive layer having excellent peelability (slight adhesiveness) after irradiation with active energy rays and further having high breaking elongation. can. In the active energy ray-curable peelable pressure-sensitive adhesive sheet of the present invention having such a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer after irradiation with the active energy rays has a high breaking elongation, so that the irradiation amount of the active energy rays is tentatively insufficient. Even when the pressure-sensitive adhesive layer is not sufficiently cured, the pressure-sensitive adhesive residue is less likely to adhere to a member to be processed such as a wafer when the pressure-sensitive adhesive sheet is peeled off, and the generation of adhesive residue can be suppressed. can.

Hereinafter, embodiments for carrying out the present invention will be specifically described, but the present invention is not limited thereto.
Some terms herein will be described.
"(Meta) acrylic" means acrylic or methacrylic, "(meth) acryloyl" means acryloyl or methacrylic, and "(meth) acrylate" means acrylate or methacrylate.
The "acrylic resin" is a resin obtained by polymerizing a polymerization component containing at least one (meth) acrylate-based monomer.
The term "sheet" is not particularly distinguished from "film" or "tape", and is described as a meaning including these.

"Number average molecular weight (Mn)" is a number average molecular weight converted to standard polystyrene molecular weight, and is a high-speed liquid chromatograph ("ACQUITY APC system" manufactured by Waters) with a column: ACQUITY APC XT 450, ACQUITY APC. It is measured by using one XT 200 and two ACQUITY APC XT 45 in series for a total of four.
"Weight average molecular weight (Mw)" is a weight average molecular weight converted to standard polystyrene molecular weight, and is shown in a high performance liquid chromatograph ("Waters 2695 (main body)" and "Waters 2414 (detector)" manufactured by Waters Japan, Inc.). Column: Chromatography GPC KF-806L (exclusion limit molecular weight: 2 × 10 ⁷ , separation range: 100 to 2 × 10 ⁷ , theoretical number of stages: 10,000 stages / piece, filler material: styrene-divinylbenzene copolymer, filling It is measured by using three series of agent particle size (10 μm).
The "dispersity" is determined by weight average molecular weight (Mw) / number average molecular weight (Mn).

The "glass transition temperature" can be obtained from the following Fox formula from the type and mass fraction of the monomer units constituting the copolymer. In the present specification, the glass transition temperature obtained from the Fox equation is also referred to as "calculated glass transition temperature".
1 / (273 + Tg) = Σ {Wi / (273 + Tgi)}
In the formula, Tg is the glass transition temperature (° C.) of the copolymer, Wi is the weight fraction of the monomer unit derived from the monomer i constituting the copolymer, and Tgi is the homopolymer of the monomer i. Indicates the glass transition temperature (° C). Tgi is usually measured by a differential scanning calorimeter (DSC), and can be measured by a method compliant with JIS K7121-1987 or JIS K6240. In addition, the value of Tgi is described in the Polymer Handbook [Polymer HandBook, J. Mol. It can also be obtained using this value when described in Brandrup, Interscience, 1989].

<Active energy ray-curable release type pressure-sensitive adhesive composition>
The active energy ray-curable release type pressure-sensitive adhesive composition of the present invention (hereinafter, may be simply abbreviated as "pressure-sensitive adhesive composition") is used for forming a pressure-sensitive adhesive layer on one side of a base sheet. It is preferably used. The pressure-sensitive adhesive layer is formed, for example, by applying a pressure-sensitive adhesive composition on a base material sheet and cross-linking the pressure-sensitive adhesive composition, whereby a pressure-sensitive adhesive sheet is obtained. The pressure-sensitive adhesive sheet is, for example, attached to a member to be processed such as a metal plate, a plastic plate, or a semiconductor wafer, and then the pressure-sensitive adhesive layer is cured by irradiation with active energy rays to reduce the adhesive strength of the pressure-sensitive adhesive layer. It can be easily peeled off from the member to be machined.

The pressure-sensitive adhesive composition of the present invention contains an ethylenically unsaturated group-containing acrylic resin (A). The ethylenically unsaturated group-containing acrylic resin (A) has an ethylenically unsaturated group-containing structural moiety (α) having a number average molecular weight of 1,000 to 300,000 on the side chain of the acrylic resin.
Hereinafter, the ethylenically unsaturated group-containing acrylic resin (A), which is a constituent component of the pressure-sensitive adhesive composition of the present invention, will be described.

[Acrylic resin containing ethylenically unsaturated group (A)]
The ethylenically unsaturated group-containing acrylic resin (A) used in the present invention may have an ethylenically unsaturated group-containing structural moiety (α) having a number average molecular weight of 1,000 to 300,000 on the side chain of the acrylic resin. There is no particular limitation.

Examples of the ethylenically unsaturated group-containing structural site (α) include the following structural sites (1) to (3), and the structural site (1) is particularly preferable from the viewpoint of ease of reaction.
(1) Ethylene which is a structural moiety derived from a hydroxyl group-containing macromonomer (α1) and is formed by a reaction between a hydroxyl group derived from a hydroxyl group-containing macromonomer (α1) and an isocyanate group of an isocyanate group-containing ethylenically unsaturated compound (α2). Sexual unsaturated group-containing structural site.
(2) A structural moiety derived from an acid-containing macromonomer, which is an ethylenically unsaturated group-containing structural moiety obtained by reacting a carboxy group derived from an acid-containing macromonomer with a vinyl ether group of a vinyl ether group-containing ethylenically unsaturated compound.
(3) A structural moiety derived from an acid-containing macromonomer, which is an ethylenically unsaturated group-containing structural moiety obtained by reacting a carboxy group derived from an acid-containing macromonomer with a glycidyl ether group of an ethylenically unsaturated compound containing a glycidyl ether group. ..

The method for preparing the structural portion of (1) above is not particularly limited, and for example, after forming a graft copolymer of an acrylic resin using a hydroxyl group-containing macromonomer (α1) having a predetermined number average molecular weight as a polymerization component at least. , The ethylenically unsaturated group-containing structural moiety (α) is introduced by reacting the hydroxyl group derived from the hydroxyl group-containing macromonomer (α1) with the isocyanate group of the isocyanate group-containing ethylenically unsaturated compound (α2). An unsaturated group-containing acrylic resin (A) can be obtained.
The polymerization component for forming the graft copolymer may contain other monomers in addition to the above-mentioned hydroxyl group-containing macromonomer (α1). Examples of other monomers include (meth) acrylic acid alkyl ester (α3), hydroxyl group-containing monomer (α4) (excluding the hydroxyl group-containing macromonomer (α1)), and other copolymerizable monomers (α5). Among these, it is preferable to contain a hydroxyl group-containing monomer (α4).
Hereinafter, the ethylenically unsaturated group-containing acrylic resin (A) having the structural portion (α) of the above (1) will be described in more detail. First, the hydroxyl group-containing macromonomer (α1) will be described.

[Hydroxy group-containing macromonomer (α1)]
The hydroxyl group-containing macromonomer (α1) is a high-molecular-weight monomer having a hydroxyl group in the side chain and having a polymerizable functional group, and it is particularly preferable to have a polymerizable unsaturated group at the end of the polymer chain.

The polymer chain (main chain) portion constituting the hydroxyl group-containing macromonomer (α1) is not particularly limited as long as it is a hydroxyl group-containing monomer having a hydroxyl group in the side chain, but is a polymer chain linked by a carbon-carbon bond. The macromonomer containing a hydroxyl group-containing (meth) acrylate-based monomer as a constituent unit is preferable in terms of compatibility with other copolymerization components (α3) to (α5) and polymerizability.

Examples of the hydroxyl group-containing (meth) acrylate-based monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate. (Meta) acrylic acid hydroxyalkyl ester such as 8-hydroxyoctyl (meth) acrylate: Caprolactone-modified 2-hydroxyethyl (meth) acrylate and other caprolactone-modified monomers: Diethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate and other oxy Alkylene-modified monomer: Primary hydroxyl group-containing monomer such as 2-acryloyloxyethyl-2-hydroxyethylphthalic acid; 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxy Secondary hydroxyl group-containing monomers such as propyl (meth) acrylate; tertiary hydroxyl group-containing monomers such as 2,2-dimethyl2-hydroxyethyl (meth) acrylate can be mentioned.
Among these, a primary hydroxyl group-containing monomer is preferable, and 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are more preferable, because they are excellent in reactivity with the cross-linking agent (B) described later.

The content of the structural moiety derived from the hydroxyl group-containing monomer such as the hydroxyl group-containing (meth) acrylate-based monomer in the hydroxyl group-containing macromonomer (α1) is preferably 1 to 100% by weight, more preferably 10 to 90% by weight, and 15 ~ 70% by weight is particularly preferable. Within the above range, it is preferable because it is excellent in curability by active energy rays such as ultraviolet rays and the elongation at break is good.

The number average molecular weight (Mn) of the hydroxyl group-containing macromonomer (α1) is preferably 1,000 to 300,000, more preferably 2,000 to 100,000, and particularly preferably 4,000 to 20,000. When Mn is at least the lower limit value, improvement in elongation at break is likely to occur, which is preferable. On the other hand, when Mn is not more than the upper limit value, copolymerization with the monomer is easy to proceed, and stable production is easy, which is preferable.

The glass transition temperature (Tg) of the hydroxyl group-containing macromonomer (α1) is preferably −100 to 150 ° C., more preferably −70 to 130 ° C., and particularly preferably −50 to 120 ° C. from the viewpoint of durability. ..

Examples of the raw material monomer other than the hydroxyl group-containing monomer for obtaining the hydroxyl group-containing macromonomer (α1) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and i-propyl (meth). ) Acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-lauryl (meth) acrylate, n-stearyl (meth) acrylate Alkyl (meth) acrylates such as (meth) acrylic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid. , 2- (meth) acryloyloxypropylphthalic acid, 2- (meth) acryloyloxyethyl maleic acid, 2- (meth) acryloyloxypropylmaleic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) Acryloyloxypropyl Succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, monomethyl itaconate and other carboxy group-containing vinyl monomers; Vinyl-based monomer; Epoxy group-containing vinyl-based monomer such as glycisyl (meth) acrylate, glycisyl α-ethyl acrylate, 3,4-epoxybutyl (meth) acrylate; dimethylaminoethyl (meth) acrylate, diethylaminoethyl ( Amino group-containing (meth) acrylate-based vinyl monomer such as meta) acrylate; (meth) acrylamide, Nt-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) Vinyl-based monomers containing amide groups such as acrylamide, N-butoxymethyl (meth) acrylamide, diacetone acrylamide, maleic acid amide, maleimide, etc .; styrene, α-methylstyrene, vinyltoluene, (meth) acrylonitrile, vinyl chloride. , Vinyl acetate, vinyl propionate and other vinyl-based monomers; divinylbenzene, ethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, Triethylene glycol di (meth) acrylate, tetraethylene glycol Examples thereof include di (meth) acrylate, tripropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and allyl (meth) acrylate.
As the raw material monomer other than the hydroxyl group-containing monomer, one selected from the above raw material monomers may be used alone, or two or more thereof may be used in combination.

As the raw material monomer other than the hydroxyl group-containing monomer, an alkyl (meth) acrylate is preferable, a (meth) alkyl acrylate having an alkyl having 1 to 8 carbon atoms is preferable, and further, a methyl (meth) acrylate and a butyl (meth) acrylate are preferable. Acrylate is preferable in terms of compatibility with other copolymerization components (α3) to (α5) and copolymerizability.

Further, as the raw material monomer, a carboxy group-containing vinyl-based monomer, an acid anhydride group-containing vinyl-based monomer, an amino group-containing (meth) acrylate-based vinyl-based monomer, and an amide group-containing vinyl-based single amount. One of the monomers selected from the group consisting of bodies can be used alone, or two or more thereof can be used in combination.

As the hydroxyl group-containing macromonomer (α1), one produced by a known method may be used, or a commercially available one may be used.
Known production methods include, for example, a method of producing using a cobalt chain transfer agent, a method of using an α-substituted unsaturated compound such as α-methylstyrene dimer as a chain transfer agent, and a method of chemically bonding a polymerizable group. , Method by thermal decomposition, etc.

Among these, as a method for producing the hydroxyl group-containing macromonomer (α1), a method using a cobalt chain transfer agent is preferable in that there are few production steps and a catalyst having a high chain transfer constant is used.

Examples of the method for producing the hydroxyl group-containing macromonomer (α1) using the cobalt chain transfer agent include a massive polymerization method, a solution polymerization method and an aqueous dispersion polymerization method. Examples of the aqueous dispersion polymerization method include a suspension polymerization method and an emulsification polymerization method. Of these polymerization methods, the aqueous dispersion polymerization method is preferable because the recovery step is simple.

The content of the hydroxyl group-containing macromonomer (α1) is preferably 0.1 to 50% by weight, more preferably 0.1 to 50% by weight, based on the polymerization component constituting the ethylenically unsaturated group-containing acrylic resin (A). It is 1 to 30% by weight, particularly preferably 5 to 25% by weight. Within such a content range, the characteristics of the hydroxyl group-containing macromonomer (α1) can be exhibited, and copolymerization with the monomer is easy to proceed, which is preferable in that stable production is easy.

[(Meta) Acrylic Acid Alkyl Ester (α3)]
The (meth) acrylic acid alkyl ester (α3) refers to a monomer having an alkyl group and having a polymerizable functional group, and the (meth) acrylic acid alkyl ester (α3) has, for example, the number of carbon atoms of the alkyl group. , Usually 1 to 20 (preferably 1 to 18, more preferably 1 to 12, particularly preferably 1 to 8), preferably an aliphatic (meth) acrylic acid alkyl ester. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, n-propyl (meth) acrylate, n. -Hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate and the like can be mentioned. .. One of the monomers selected from these can be used alone, or two or more thereof can be used in combination.

Among these (meth) acrylic acid alkyl esters (α3), methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2 -Ethylhexyl (meth) acrylate is preferable, and n-butyl (meth) acrylate is particularly preferable.

The content of the (meth) acrylic acid alkyl ester (α3) is preferably 10% by weight or more, more preferably 30% by weight, based on the polymerization component constituting the ethylenically unsaturated group-containing acrylic resin (A). % Or more, particularly preferably 50 to 95% by weight, still more preferably 60 to 90% by weight. If the content is too small, the sticky physical properties and durability tend to decrease.

[Hydroxy group-containing monomer (α4)]
The hydroxyl group-containing monomer (α4) refers to a monomer having a hydroxyl group and having a polymerizable functional group, and a (meth) acrylate-based monomer is preferable. Examples of the (meth) acrylate-based hydroxyl group-containing monomer (α4) include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, and 6-hydroxyhexyl (meth). ) Acrylate hydroxyalkyl esters such as acrylates and 8-hydroxyoctyl (meth) acrylates: caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth) acrylates, oxy such as diethylene glycol (meth) acrylates and polyethylene glycol (meth) acrylates. Alkylene-modified monomer: Primary hydroxyl group-containing monomer such as 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, N-methylol (meth) acrylamide, hydroxyethylacrylamide; 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl Secondary hydroxyl group-containing monomers such as (meth) acrylate and 3-chloro2-hydroxypropyl (meth) acrylate; hydroxyl group-containing monomers such as 2,2-dimethyl2-hydroxyethyl (meth) acrylate can be mentioned.

Among the above hydroxyl group-containing monomers (α4), a primary hydroxyl group-containing monomer is preferable in terms of excellent reactivity with a cross-linking agent, and 2-hydroxyethyl (meth) acrylate is preferable in terms of stability during polymerization. It is preferable to use 4-hydroxybutyl (meth) acrylate because of its high reactivity and short aging. Further, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable because they have few impurities such as di (meth) acrylate and are easy to produce.

As the hydroxyl group-containing monomer (α4), it is preferable to use one having a content ratio of di (meth) acrylate as an impurity of 0.5% by weight or less, more preferably 0.2% by weight or less, particularly. It is preferably 0.15% by weight or less, and specifically, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxypropyl (meth) acrylate having such an impurity amount are particularly preferable. ..

The number average molecular weight of the hydroxyl group-containing monomer (α4) is preferably less than 1000, more preferably 200 or less, from the viewpoint of easy availability and ease of copolymerization. The lower limit of the number average molecular weight is usually 50.

The hydroxyl group-containing monomer (α4) is preferably contained in a range of 30% by weight or less, preferably 0.01 to 30% by weight, based on the polymerization component constituting the ethylenically unsaturated group-containing acrylic resin (A). Is more preferable, particularly 0.1 to 20% by weight, more preferably 1 to 15% by weight, and particularly preferably 3 to 10% by weight.

[Other copolymerizable monomers (α5)]
The other copolymerizable monomer (α5) is a copolymerizable ethylenically unsaturated monomer, and a (meth) acrylate-based monomer is preferable. Examples of the (meth) acrylate-based other copolymerizable monomer (α5) include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, orthophenylphenoxyethyl (meth) acrylate and the like. Aromatic ring-containing monomer; alicyclic such as cyclohexyl (meth) acrylate, cyclohexyloxyalkyl (meth) acrylate, t-butylcyclohexyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, etc. Monomer contained; 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, 2-butoxydiethylene glycol (meth) acrylate, methoxydiethylene glycol (Meta) acrylate, methoxytriethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, octoxypolyethylene glycol-polypropylene glycol-mono (meth) Examples thereof include ether chain-containing monomers such as acrylate, lauroxypolyethylene glycol mono (meth) acrylate, and stearoxypolyethylene glycol mono (meth) acrylate.

Moreover, a copolymerizable monomer having a polar group other than a hydroxyl group, for example, a carboxy group-containing monomer, a nitrogen atom-containing monomer and the like can also be mentioned.
Examples of the carboxy group-containing monomer include (meth) acrylic acid and dimer acid of acrylic acid such as β-carboxyethyl acrylate. Among them, (meth) in terms of moisture resistance and stability during polymerization. Acrylic acid is preferred.

Examples of the nitrogen atom-containing monomer include an amino group-containing monomer, an amide group-containing monomer, and other nitrogen atom-containing monomers.

Examples of the amino group-containing monomer include a primary amino group-containing monomer such as aminomethyl (meth) acrylate and aminoethyl (meth) acrylate; and a secondary amino group-containing monomer such as t-butylaminoethyl (meth) acrylate; Examples thereof include a tertiary amino group-containing monomer such as ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and diethylaminoethyl (meth) acrylate.
Among the amino group-containing monomers, the tertiary amino group-containing monomer is preferable in terms of high cross-linking promoting effect and high storage stability of the resin.

Examples of the amide group-containing monomer include (meth) acrylamide; methoxymethyl (meth) acrylamide, ethoxymethyl (meth) acrylamide, propoxymethyl (meth) acrylamide, isopropoxymethyl (meth) acrylamide, and n-butoxymethyl (meth). ) Acrylamide (meth) acrylamide-based monomers such as acrylamide and isobutoxymethyl (meth) acrylamide; Dialkyl (meth) acrylamide-based monomers such as dimethyl (meth) acrylamide and diethyl (meth) acrylamide; N- (hydroxymethyl) acrylamide and the like. The hydroxyl group-containing amide monomer of the above; a heterocyclic amide monomer such as (meth) acrylamide and the like; and the like.
Among the amide group-containing monomers, (meth) acryloylmorpholine, alkoxyalkyl (meth) acrylamide-based monomers, and dialkyl (meth) acrylamide-based monomers are preferable in terms of the stability of the resin solution.

One kind selected from the above-mentioned other copolymerizable monomers (α5) can be used alone, or two or more kinds can be used in combination.
The content of the other copolymerizable monomer (α5) is preferably 25% by weight or less with respect to the polymerization component so as not to impair the effect of the present invention.

When forming a graft copolymer of an acrylic resin using a hydroxyl group-containing macromonomer (α1) as a polymerization component at least, a polymerization component containing at least a hydroxyl group-containing macromonomer (α1) is used, for example, in an organic solvent. Polymerization is carried out by mixing or dropping the polymerization component and the polymerization initiator. The polymerization component may appropriately contain a (meth) acrylic acid alkyl ester (α3), a hydroxyl group-containing monomer (α4), and another copolymerizable monomer (α5). Of these monomers, the (meth) acrylic acid alkyl ester (α3) is preferable in terms of ease of polymerization and adjustment of adhesive characteristics, and the hydroxyl group-containing monomer (α1) is compatible with the hydroxyl group-containing macromonomer (α1). α4) is preferable.

The above polymerization reaction can be carried out by a known polymerization method such as a solution radical polymerization method, a suspension polymerization method, a bulk polymerization method, and an emulsion polymerization method. Among these, the solution radical polymerization method and the massive polymerization method are preferable, and the solution radical polymerization method is more preferable.

In the solution radical polymerization method, for example, the above-mentioned polymerization component and the polymerization initiator are mixed or dropped in an organic solvent, and the polymerization is carried out in a reflux state or usually at 50 to 98 ° C. for about 0.1 to 20 hours.

Examples of the organic solvent used in the polymerization reaction include aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as hexane; esters such as ethyl acetate and butyl acetate; n-propyl alcohol and isopropyl alcohol. And other aliphatic alcohols; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; and the like.

Among these organic solvents, ethyl acetate, acetone, methyl ethyl ketone, butyl acetate, toluene, methyl Isobutyl ketone is preferably used, and more preferably ethyl acetate, acetone, or methyl ethyl ketone.
One kind selected from these organic solvents can be used alone, or two or more kinds can be used in combination.
The amount of these organic solvents used is usually 10 to 900 parts by weight with respect to 100 parts by weight of the polymerization component.

Examples of the polymerization initiator used in such a solution radical polymerization method include 2,2'-azobis (isobutyronitrile) and 2,2'-azobis (2,4-), which are ordinary radical polymerization initiators. Azo-based polymerization of dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (methylpropionic acid), etc. Initiators include organic peroxides such as benzoyl peroxide, laurolyl peroxide, dit-butyl peroxide, and cumene hydroperoxide, which can be appropriately selected and used according to the monomer to be used. One of these polymerization initiators can be used alone or in combination of two or more.
The amount of these polymerization initiators used is usually 0.01 to 5% by weight based on the polymerization component.

The weight average molecular weight of the graft copolymer obtained by the above polymerization method is usually 100,000 to 2,000,000, preferably 150,000 to 1,500,000, more preferably 200,000 to 1,200,000, and particularly preferably 300,000 to 1,000,000. be. If the weight average molecular weight is too small, the contamination property with respect to the workpiece tends to be high, and if it is too large, the coatability tends to be deteriorated, and it tends to be disadvantageous in terms of cost.

The dispersity (weight average molecular weight / number average molecular weight) of the graft copolymer is preferably 20 or less, more preferably 10 or less, particularly preferably 7 or less, and even more preferably 5 or less. If the degree of dispersion is too high, the contamination with the workpiece tends to increase. The lower limit of the dispersity is usually 1.1 from the point of view of the manufacturing limit.

The viscosity of the graft copolymer at 25 ° C. is preferably 5 to 50,000 mPa · s, more preferably 10 to 10,000 mPa · s. If the viscosity is out of the above range, the coatability tends to decrease. The viscosity is measured by an E-type viscometer.

The glass transition temperature (Tg) of the graft copolymer is usually 40 ° C. or lower, preferably −60 to 20 ° C., more preferably −50 to −5 ° C., and particularly preferably −40 to −10 ° C. .. If the glass transition temperature is too high, the adhesiveness tends to decrease, and if it is too low, the contamination with the workpiece tends to increase.

[Isocyanate group-containing ethylenically unsaturated compound (α2)]
The isocyanate group-containing ethylenically unsaturated compound (α2) is reacted with the graft copolymer of the acrylic resin obtained through the above polymerization step to carry out urethanization.
The isocyanate group-containing ethylenically unsaturated compound (α2) refers to a monomer having an isocyanate group and having a polymerizable functional group. Examples of the isocyanate group-containing ethylenically unsaturated compound (α2) include 2- (meth) acryloyloxyethyl isocyanate, 3- (meth) acryloyloxy-n-propyl isocyanate, and 2- (meth) acryloyloxyisopropyl isocyanate, 4 -(Meta) acryloyloxy-n-butylisocyanate, 2- (meth) acryloyloxy-tert-butylisocyanate, 2- (meth) acryloyloxybutyl-4-isocyanate, 2- (meth) acryloyloxybutyl-3-isocyanate , 2- (meth) acryloyloxybutyl-2-isocyanate, 2- (meth) acryloyloxybutyl-1-isocyanate, 5- (meth) acryloyloxy-n-pentylisocyanate, 6- (meth) acryloyloxy-n- Hexyl isocyanate, 7- (meth) acryloyloxy-n-heptyl isocyanate, 2- (isocyanatoethyloxy) ethyl (meth) acrylate, 3- (meth) acryloyloxyphenyl isocyanate, 4- (meth) acryloyloxyphenyl isocyanate, Examples thereof include 1,1-bis ((meth) acryloyloxymethyl) methyl isocyanate, 1,1-bis ((meth) acryloyloxymethyl) ethyl isocyanate, and 2'-pentenoyl-4-oxyphenyl isocyanate. One selected from these compounds may be used alone, or two or more thereof may be used in combination.
Among these compounds, (meth) acrylate-based monomers are preferable because of their ease of synthesis and availability of raw materials, and further, 2- (meth) acryloyloxyethyl isocyanate and 2- (meth) acryloyloxy are preferable. Ethyl isocyanate, 2- (isocyanatoethyloxy) ethyl (meth) acrylate, 2- (isocyanatoethyloxy) ethyl (meth) acrylate, and 1,1-bis ((meth) acryloyloxymethyl) ethyl isocyanate are preferred.

When the graft copolymer is reacted with the isocyanate group-containing ethylenically unsaturated compound (α2), the hydroxyl group derived from the hydroxyl group-containing macromonomer (α1) contained in the graft copolymer and the ethylenically unsaturated compound (α2) Reacts with the isocyanate group of the above to form an ethylenically unsaturated group-containing structural site containing an ethylenically unsaturated bond and a urethane bond in the molecule.

The ratio of both compounds used in the reaction is appropriately set in consideration of the ratio of the hydroxyl group to the isocyanate group, and differs depending on the type of both compounds.

The reaction of both compounds may be carried out in the presence of a reaction catalyst, and the reaction rate can be adjusted by the amount of the reaction catalyst added.
As the reaction catalyst, a known reaction catalyst 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, and titanium diiso. Examples thereof include propoxybis (ethylacetacetate), bismastris (2-ethylhexanoate) and a mixture of 2-ethylhexanoic acid. One selected from these reaction catalysts can be used alone or in combination of two or more.

The reaction temperature when reacting both compounds is preferably −10 to 100 ° C., more preferably 0 to 80 ° C. The reaction time is preferably 30 minutes to 50 hours, more preferably 1 hour to 20 hours.

When the two compounds are reacted, a polymerization inhibitor may be added to the reaction system, if necessary.
As the polymerization inhibitor, a commonly used agent can be used, and for example, a phenol-based compound, a hydroquinone-based compound, or the like can be used. Specific examples of the polymerization inhibitor include hydroquinone, methoxyhydroquinone, catechol, p-tert-butylcatechol, cresol, 2,6-di-tert-butyl-4-methylphenol (BHT) and the like.
In addition, known additives may be added in the reaction of both compounds depending on the purpose.

The ethylenically unsaturated group-containing acrylic resin (A) in the present invention has an ethylenically unsaturated group-containing structural moiety (α) having a number average molecular weight of 1,000 to 300,000 in its side chain.
For example, the ethylenically disabled body formed by the reaction between the structural site of (1) above, specifically, the hydroxyl group derived from the hydroxyl group-containing macromonomer (α1) and the isocyanate group of the isocyanate group-containing ethylenically unsaturated compound (α2). If it is a saturated group-containing structural moiety, the number average molecular weight of the structural moiety in (1) above is the sum of the number average molecular weights of the hydroxyl group-containing macromonomer (α1) and the isocyanate group-containing ethylenically unsaturated compound (α2). be.
The number average molecular weight of the ethylenically unsaturated group-containing structural moiety (α) is preferably 2000 to 250,000, more preferably 3000 to 100,000, particularly preferably 4000 to 50,000, and even more preferably 5000 to 30,000. If the number average molecular weight of the ethylenically unsaturated group-containing structural site (α) is too low, it tends to be difficult to improve the elongation at break, and if the number average molecular weight is too high, copolymerizability with other monomers tends to occur. It tends to be difficult to manufacture stably.
If the number average molecular weight of the ethylenically unsaturated group-containing structural moiety (α) is the structural moiety of (1) above, the hydroxyl group-containing macromonomer (α1) or the isocyanate group-containing ethylenically unsaturated compound (α2) can be used. The setting can be appropriately made by adjusting the number average molecular weight.

The addition reaction rate between the hydroxyl group derived from the hydroxyl group-containing macromonomer (α1) contained in the graft copolymer and the isocyanate group of the isocyanate group-containing ethylenically unsaturated compound (α2), that is, the urethanization rate is 5 to 99 mol%. Is preferable, and 10 to 90 mol% is more preferable. If the urethanization rate is too low, the adhesive strength after irradiation with active energy rays such as ultraviolet rays tends to be difficult to sufficiently decrease, and if the urethanization rate is too high, the urethane reaction is not completed and unreacted isocyanate. The group-containing ethylenically unsaturated compound (α2) tends to remain.

The ethylenically unsaturated group-containing acrylic resin (A) has an ethylenically unsaturated group content of usually 5 to 250 mmol / 100 g, preferably 10 to 200 mmol / 100 g, and more preferably 15 to 100 mmol. / 100g. If the content of the ethylenically unsaturated group is too low, the peelability due to irradiation with active energy rays tends to decrease, and if the content of the ethylenically unsaturated group is too high, the stain resistance to the workpiece after peeling tends to decrease. Tends to decline.

The content of the ethylenically unsaturated group of the ethylenically unsaturated group-containing acrylic resin (A) can be obtained from the following formula.
Ethylene unsaturated group content (mmol / 100g)
= Amount of hydroxyl group (mmоl%) contained in 100 g of acrylic resin (A) containing ethylenically unsaturated group x urethanization rate (%) / 100

The ethylenically unsaturated group-containing acrylic resin (A) used in the present invention preferably contains a hydroxyl group that reacts with the cross-linking agent (B) described later, and a cross-linked structure is formed thereby forming an active energy ray. Adhesive strength before irradiation is improved.
The content of the hydroxyl group in the ethylenically unsaturated group-containing acrylic resin (A) is usually 0.01 to 20% by weight, preferably 0.05 to 10% by weight, and more preferably 0.1 to 5% by weight. .. If the content of hydroxyl groups is too low, the cohesive force of the adhesive will decrease, which tends to cause adhesive residue. If the content of hydroxyl groups is too high, the flexibility and adhesive strength of the adhesive will decrease, and the adhesive will be covered. There is a tendency for floating to occur with the machined member.

[Crosslinking agent (B)]
The pressure-sensitive adhesive composition of the present invention preferably further contains a cross-linking agent (B) in order to improve the pressure-sensitive adhesive force before irradiation with active energy rays.
The cross-linking agent (B) reacts with the functional groups in the ethylenically unsaturated group-containing acrylic resin (A) to form a cross-linked structure. Examples thereof include a cross-linking agent, a melamine-based cross-linking agent, an aldehyde-based cross-linking agent, an amine-based cross-linking agent, and a metal chelate-based cross-linking agent. Among these, it is preferable to use an isocyanate-based cross-linking agent from the viewpoint of reactivity with the ethylenically unsaturated group-containing acrylic resin (A).

The isocyanate-based cross-linking agent contains at least two isocyanate groups, and is, for example, a tolylene diisocyanate-based cross-linking agent such as 2,4-tolylene diisocyanate or 2,6-tolylene diisocyanate: 1,3-xylylene. Xylylene diisocyanate-based cross-linking agent such as isocyanate: Diphenylmethane-Diphenylmethane-based cross-linking agent such as 4,4-diisocyanate: 1,5-Aromatic isocyanate-based cross-linking agent such as naphthalenediocyanate-based cross-linking agent such as naphthalenedi isocyanate; Isophoron diisocyanate, Alicyclic isocyanates such as 1,4-cyclohexanediisocyanate, 4,4'-dicyclohexylmethanediisocyanate, methylcyclohexanediisocyanate, isopropyridendicyclohexyl-4,4'-diisocyanate, 1,3-diisocyanatomethylcyclohexane, norbornandiisocyanate. Examples thereof include aliphatic isocyanate-based cross-linking agents such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate; and adducts, bullets, and isocyanurates of the isocyanate-based compounds.

Among these isocyanate-based cross-linking agents, the tolylene diisocyanate-based cross-linking agent is preferable in terms of pot life and durability, and the xylylene diisocyanate-based cross-linking agent or the isocyanurate skeleton-containing isocyanate-based cross-linking agent is preferable in terms of shortening the aging time, and is aromatic. Group-free isocyanate-based cross-linking agents are preferable in terms of resistance to yellowing. Specifically, among these, an adduct form of trimethylolpropane and an isocyanate of any one of tolylene diisocyanate, xylylene diisocyanate and hexamethylene diisocyanate, and a nurate form have a balance of durability, pot life and cross-linking rate. It is preferable in that it is excellent in.

Examples of the epoxy-based cross-linking agent include bisphenol A / epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, and 1,6-hexanediol diglycidyl ether. , Trimethylol propanetriglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether and the like.

Examples of the aziridine-based cross-linking agent include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, and N, N'-diphenylmethane-4,4. '-Bis (1-aziridinecarboxyamide), N, N'-hexamethylene-1,6-bis (1-aziridinecarboxyamide) and the like can be mentioned.

Examples of the melamine-based cross-linking agent include hexamethoxymethyl melamine, hexaethoxymethyl melamine, hexapropoxymethyl melamine, hexabutoxymethyl melamine, hexapentyloxymethyl melamine, hexahexyl oxymethyl melamine, and melamine resin.

Examples of the aldehyde-based cross-linking agent include glyoxal, malondialdehyde, succindialdehyde, maleindialdehyde, glutardaldehyde, formaldehyde, acetaldehyde, and benzaldehyde.

Examples of the amine-based cross-linking agent include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetraamine, diethylenetriamine, triethyltetraamine, isophoronediamine, amino resin, polyamide and the like.

Examples of the metal chelate-based cross-linking agent include acetylacetone and acetoacetyl ester coordination compounds of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, panadium, chromium and zirconium. Can be mentioned.

One selected from these cross-linking agents may be used alone or in combination of two or more.

The content of the cross-linking agent (B) is usually preferably 0.005 to 30 parts by weight, more preferably 0, with respect to 100 parts by weight of the ethylenically unsaturated group-containing acrylic resin (A). It is 01 to 10 parts by weight, particularly preferably 0.03 to 5 parts by weight, and more preferably 0.05 to 3 parts by weight. If the amount of the cross-linking agent (B) is too small, the cohesive force of the adhesive is reduced and tends to cause adhesive residue, and if the amount of the cross-linking agent (B) is too large, the softness and adhesive strength of the adhesive are reduced. , There is a tendency for floating to occur between the member to be machined and the member to be machined.

[Photopolymerization Initiator (C)]
The pressure-sensitive adhesive composition of the present invention preferably further contains a photopolymerization initiator (C) from the viewpoint of improving the curability in activation energy ray irradiation and improving the peelability after activation energy ray irradiation.
As the photopolymerization initiator (C), one that generates radicals by the action of active energy rays can be used, and examples thereof include the following photopolymerization initiators.
Diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl Phenyl Ketone, 1- [4- (2-Hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propane-1-one, 2-methyl-2-morpholino (4-thiomethylphenyl) propane- 1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone, 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4- (4- (4-) Alkylphenones such as morpholinyl) phenyl] -1-butanone, 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone oligomer;
Benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether;
Benzophenone, o-Methyl benzoyl benzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenylsulfide, 3,3', 4,4'-tetra (tert-butylperoxycarbonyl) benzophenone, 2,4 , 6-trimethylbenzophenone, 4-benzoyl-N, N-dimethyl-N- [2- (1-oxo-2-propenyloxy) ethyl] benzenemethnaminium bromide, (4-benzoylbenzyl) trimethylammonium chloride, etc. Benzophenones;
2-Isopropylthioxanthone, 4-Isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2- (3-dimethylamino-2-hydroxy) -3,4- Thioxanthons such as dimethyl-9H-thioxanthone-9-onemesochloride;
2,4,6-trimethylbenzoyl-diphenylphosphinoxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphinoxide, bis (2,4,6-trimethylbenzoyl) -phenyl Acylphosphon oxides such as phosphinoxide.
Of these, alkylphenones, particularly 1-hydroxycyclohexylphenylketones and acylphosphon oxides, particularly 2,4,6-trimethylbenzoyl-diphenylphosphinoxide.
One selected from these photopolymerization initiators can be used alone, or two or more thereof can be used in combination.

The content of the photopolymerization initiator (C) is usually preferably 0.1 to 20 parts by weight, more preferably 0.1 to 20 parts by weight, based on 100 parts by weight of the ethylenically unsaturated group-containing acrylic resin (A). It is 0.5 to 15 parts by weight, particularly preferably 0.5 to 10 parts by weight.
If the content of the photopolymerization initiator (C) is too small, the peelability after irradiation with active energy rays tends to decrease, and if it is too large, the contamination property to the workpiece tends to increase.

Further, as an auxiliary agent for these photopolymerization initiators (C), for example, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Mihiler ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethyl. Benzoic acid, ethyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoic acid (n-butoxy), isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanson , 2,4-Diisopropylthioxanson and the like can also be used in combination. One selected from these auxiliaries may be used alone or in combination of two or more.

[Other ingredients]
The pressure-sensitive adhesive composition of the present invention may contain other components as long as the effects of the present invention are not impaired. For example, an ethylenically unsaturated compound is used for the purpose of improving the peelability after irradiation with active energy rays. Can be further contained. Further, the pressure-sensitive adhesive composition of the present invention contains additives such as antistatic agents, antioxidants, plasticizers, fillers, pigments, diluents, antioxidants, UV absorbers, UV stabilizers, and tackifier resins. It may be further contained. One selected from these additives can be used alone, or two or more thereof can be used in combination. In particular, antioxidants are effective in maintaining the stability of the pressure-sensitive adhesive layer. The content of the antioxidant when it is contained is not particularly limited, but is preferably 0.01 to 5% by weight in the pressure-sensitive adhesive composition. In addition to the additives, a small amount of impurities and the like contained in the raw materials for producing the constituent components of the pressure-sensitive adhesive composition may be contained.

Thus, it contains at least an ethylenically unsaturated group-containing acrylic resin (A), preferably a cross-linking agent (B) and / or a photopolymerizable initiator (C), and optionally other components. By doing so, the pressure-sensitive adhesive composition of the present invention can be obtained.

The pressure-sensitive adhesive composition of the present invention does not contain the above-mentioned cross-linking agent (B) as an essential component, but by containing the cross-linking agent (B), cross-linking becomes easy and the performance as a pressure-sensitive adhesive can be more easily exhibited. .. Further, the pressure-sensitive adhesive composition of the present invention does not contain the above-mentioned photopolymerizable initiator (C) as an essential component, but by containing the photopolymerizable initiator (C), it is not ethylenic due to irradiation with active energy rays. The polymerization of the ethylenically unsaturated group contained in the saturated group-containing acrylic resin (A) is facilitated, the pressure-sensitive adhesive is easily cured, and the adhesive strength is lowered, so that the peelability can be more easily exhibited.

The pressure-sensitive adhesive composition of the present invention is usually used for dicing a substrate such as a metal plate or a plastic plate, a temporary surface-protecting pressure-sensitive adhesive sheet for a member such as a processed glass product, or a semiconductor device such as a semiconductor wafer or an electronic substrate. It is preferably used as a pressure-sensitive adhesive layer in a pressure-sensitive adhesive sheet for fixing a semiconductor, which is used in a semiconductor manufacturing process such as.
Hereinafter, the active energy ray-curable peelable adhesive sheet (hereinafter, may be simply abbreviated as “adhesive sheet”), which is the second gist of the present invention, will be described.

<Active energy ray-curable peelable adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention usually has a base material sheet, a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition of the present invention, and a release film. As a method for producing such a pressure-sensitive adhesive sheet, first, the pressure-sensitive adhesive composition of the present invention is directly applied or dissolved in an appropriate organic solvent to adjust the concentration, and then directly applied onto a release film or a base sheet. Then, for example, it is dried by heat treatment at 80 to 105 ° C. for 0.5 to 10 minutes, and this is attached to a base sheet or a release film to obtain an adhesive sheet. Further, in order to balance the sticky physical characteristics, further aging may be performed after drying.

Examples of the base material sheet include synthetic resin sheets; metal foils made of aluminum, copper, iron and the like; papers such as high-quality paper and glassin paper; textiles and non-woven fabrics made of glass fibers, natural fibers, synthetic fibers and the like. .. Examples of the material of the synthetic resin sheet include polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymers; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyfluoride. Polyfluorinated ethylene resin such as vinyl, polyvinylidene fluoride, polyethylene fluoride; polyamide such as nylon 6, nylon 6,6; polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene -Vinyl alcohol copolymers, vinyl polymers such as polyvinyl alcohol and vinylon; cellulose-based resins such as cellulose triacetate and cellophane; acrylics such as methyl polymethacrylate, ethyl polymethacrylate, ethyl polyacrylate and butyl polyacrylate. Examples thereof include based resins; polystyrene; polycarbonate; polyarylate; polyimide.
These base material sheets can be used as a single layer or as a multi-layer in which two or more kinds are laminated. Among these, the synthetic resin sheet is preferable from the viewpoint of weight reduction and the like.

Further, as the release film, for example, various synthetic resin sheets, papers, woven fabrics, non-woven fabrics and the like exemplified for the base material sheet can be released.

Further, the coating method of the pressure-sensitive adhesive composition is not particularly limited, and a general coating method can be adopted, for example, roll coating, die coating, gravure coating, comma coating, screen printing and the like. The method can be mentioned.

The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is usually preferably 10 to 200 μm, more preferably 15 to 100 μm.

As the aging conditions, the temperature is usually normal temperature (23 ° C.) to 70 ° C., and the time is usually 1 to 30 days. Specifically, for example, 23 ° C. for 1 to 20 days and 23 ° C. for 3 to 3 to 30 days. It can be carried out for 10 days at 40 ° C. for 1 to 7 days.

The gel fraction of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is preferably 10 to 99% by weight, more preferably 20 to 97% by weight, and particularly preferably 50 to 90% by weight from the viewpoint of adhesiveness. .. If the gel fraction is too low, the adhesive force to the workpiece tends to decrease, and if it is too high, the adhesive force to the workpiece tends to decrease.

The gel fraction is a measure of the degree of cross-linking (curing degree), and is calculated by, for example, the following method. The adhesive sheet is attached to a SUS mesh sheet (200 mesh), wrapped in the adhesive sheet, and then immersed in a sealed container containing ethyl acetate for 24 hours. The gel fraction is calculated by the following formula.
Gel fraction (%) = (weight (g) of adhesive layer after immersion in ethyl acetate
/ Weight of adhesive layer before immersion in ethyl acetate (g)) x 100

The gel fraction of the pressure-sensitive adhesive layer is adjusted to the above range by adjusting the type and amount of the cross-linking agent.

The pressure-sensitive adhesive sheet of the present invention can be peeled off by irradiating it with active energy rays to cure the pressure-sensitive adhesive layer and reduce the adhesive strength.
As the active energy ray, usually, far ultraviolet rays, ultraviolet rays, near ultraviolet rays, rays such as infrared rays, electromagnetic waves such as X-rays and γ-rays, as well as electron beams, proton rays, neutron rays and the like can be used. Among them, ultraviolet rays are preferable in terms of curing speed, availability of irradiation equipment, price, and the like.

The integrated irradiation amount when irradiating the above ultraviolet rays is usually 50 to 3,000 mJ / cm ² , preferably 100 to 1,000 mJ / cm ² . The irradiation time varies depending on the type of light source, the distance between the light source and the pressure-sensitive adhesive layer, the thickness of the pressure-sensitive adhesive layer, and other conditions, but may be usually several seconds, and in some cases a fraction of a second.

The adhesive strength of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet varies depending on the type of the base material sheet, the type of the member to be processed, etc. 20N / 25mm is more preferable.

The fact that the adhesive sheet of the present invention can be peeled off means that the adhesive layer becomes adhesive enough to be peeled off from the member to be processed together with the base sheet by irradiation with active energy rays, and is bonded to an uneven surface. Even when the contact area between the adhesive sheet and the adherend is different between the uneven portion and the other portion, the difference in the adhesive force applied at the time of peeling between the uneven portion and the other portion is small. For example, the coefficient of variation described in the examples is preferably less than 20, more preferably 14 or less.

The pressure-sensitive adhesive sheet of the present invention is useful as a temporary surface-protecting pressure-sensitive adhesive sheet for a substrate and a semiconductor-fixing pressure-sensitive adhesive sheet used when a semiconductor device is attached to a semiconductor manufacturing process. By irradiating with active energy rays, the adhesive layer is hardened and the adhesive strength is reduced, so that the adhesive layer can be easily peeled off from the member to be processed.

Next, an active energy ray-curable release type adhesive (hereinafter, may be simply abbreviated as “adhesive”), which is the third gist of the present invention, will be described.

<Active energy ray-curable release type adhesive>
The pressure-sensitive adhesive of the present invention contains an ethylenically unsaturated group-containing acrylic resin, a cross-linking agent (B) and a photopolymerization initiator (C).
The ethylenically unsaturated group-containing acrylic resin is not particularly limited as long as it is an acrylic resin containing an ethylenically unsaturated group in its side chain, and is contained in the pressure-sensitive adhesive composition which is the first gist of the present invention. Not only the ethylenically unsaturated group-containing acrylic resin (A), but also the ethylenically unsaturated group-containing acrylic having an ethylenically unsaturated group-containing structural portion in the side chain having a number average molecular weight outside the range of 1,000 to 300,000. It may be a based resin, and the ethylenically unsaturated group-containing structural moiety may be not only the structural moiety of (1) to (3) below but also another structural moiety.
(1) Ethylene which is a structural moiety derived from a hydroxyl group-containing macromonomer (α1) and is formed by a reaction between a hydroxyl group derived from a hydroxyl group-containing macromonomer (α1) and an isocyanate group of an isocyanate group-containing ethylenically unsaturated compound (α2). Sexual unsaturated group-containing structural site.
(2) A structural moiety derived from an acid-containing macromonomer, which is an ethylenically unsaturated group-containing structural moiety obtained by reacting a carboxy group derived from an acid-containing macromonomer with a vinyl ether group of a vinyl ether group-containing ethylenically unsaturated compound.
(3) A structural moiety derived from an acid-containing macromonomer, which is an ethylenically unsaturated group-containing structural moiety obtained by reacting a carboxy group derived from an acid-containing macromonomer with a glycidyl ether group of an ethylenically unsaturated compound containing a glycidyl ether group. ..
In the present invention, among the above, the ethylenically unsaturated group-containing acrylic resin (A) is preferable because the reaction temperature is low and the production is easy.

Further, as the cross-linking agent (B) and the photopolymerization initiator (C), the same or similar ones as described for the pressure-sensitive adhesive composition which is the first gist of the present invention can be used.
The content of the cross-linking agent (B) and the photopolymerization initiator (C) in the pressure-sensitive adhesive of the present invention is the same as or similar to each content described for the pressure-sensitive adhesive composition which is the first gist of the present invention. ..

By satisfying the following requirement [I], the pressure-sensitive adhesive of the present invention can form a pressure-sensitive adhesive layer having excellent peelability (slight adhesiveness) after irradiation with active energy rays and further having high breaking elongation. can.
[I] The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet having a cross-linked pressure-sensitive adhesive layer having a thickness of 300 μm was irradiated with ultraviolet rays having a cumulative irradiation amount of 1000 mJ / cm ² using one 80 W high-pressure mercury lamp. After allowing to stand for 30 minutes in an atmosphere of ° C. and 50% RH, the elongation at break measured by a tensile tester at a tensile speed of 300 mm / min is 90 to 300%.
The elongation at break is preferably 100 to 280%, more preferably 110 to 270%, and particularly preferably 130 to 250%.
If the breaking elongation is too high, the adhesive does not separate from the adherend indefinitely, so that the adhesive strength tends to be too high, and if it is too low, adhesive residue tends to occur.
The elongation at break can be adjusted by the degree of cross-linking of the pressure-sensitive adhesive layer. The method for measuring the elongation at break will be described in detail in Examples described later.

The pressure-sensitive adhesive of the present invention is suitably used for producing a pressure-sensitive adhesive layer in a pressure-sensitive adhesive sheet, which is the second aspect of the present invention, similarly to the pressure-sensitive adhesive composition which is the first aspect of the present invention. However, the pressure-sensitive adhesive of the present invention is not limited to the pressure-sensitive adhesive sheet, and can be applied to various other uses.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. In the following, the term "part" means a weight standard.
First, the following raw material monomers were prepared, and various ethylenically unsaturated group-containing acrylic resins were prepared as described below.

The following macromonomers were prepared as raw materials for preparing acrylic resins.

(Macromonomer 1)
Acrylic macromonomer (MMA: HEMA (weight ratio) = 75.5: manufactured by Mitsubishi Chemical Co., Ltd., which is a polymer of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) and contains a hydroxyl group in the side chain. 24.5, number average molecular weight 10400, dispersion 1.73, calculated glass transition temperature 66.3 ° C)

(Macromonomer 2)
Acrylic macromonomer (MMA: HEMA (weight ratio) = 75.5: manufactured by Mitsubishi Chemical Co., Ltd., which is a polymer of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) and contains a hydroxyl group in the side chain. 24.5, number average molecular weight 4200, dispersion 1.5, calculated glass transition temperature 66.3 ° C)

(Macromonomer 3)
Acrylic macromonomer (MMA: HEMA (weight ratio) = 75.5: manufactured by Mitsubishi Chemical Co., Ltd., which is a polymer of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) and contains a hydroxyl group in the side chain. 24.5, number average molecular weight 22600, dispersion 1.75, calculated glass transition temperature 66.3 ° C)

(Macromonomer 4)
Acrylic macromonomer which is a polymer of methyl methacrylate (MMA) and does not contain a hydroxyl group in the side chain (manufactured by Mitsubishi Chemical Corporation, number average molecular weight 10300, dispersion degree 1.91, calculated glass transition temperature 105 ° C.)

[Manufacturing of acrylic resin [I] containing ethylenically unsaturated group]
In a 4-necked round-bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, 20 parts of the macromonomer 1 (α1) prepared above, 79 parts of n-butyl acrylate (BA), 2 -Add 1 part of hydroxyethyl methacrylate (HEMA), 56 parts of ethyl acetate, 21 parts of acetone, and 0.075 part of azobisisobutyronitrile (AIBN) as a polymerization initiator, and raise the internal temperature to the boiling point to start the reaction. It was allowed to heat and heated for 2 hours. Then, 10 parts of an ethyl acetate solution containing 0.6% of 2,2'-azobis (2,4-dimethylvaleronitrile) (ADVN) was added, and the mixture was reacted at reflux temperature for 2.5 hours. After adding 10 parts of ethyl acetate solution containing 0.6% of ADVN again, the reaction was stopped at the reflux temperature for 2.5 hours, then the reaction was stopped, diluted with ethyl acetate, and the acrylic resin [I'] (cograft). Polymer: The same applies hereinafter) A solution (calculated glass transition temperature −36 ° C.) was obtained.
To the acrylic resin [I'] solution obtained above, 2-methacryloyloxyethyl isocyanate (hereinafter referred to as "MOI") (manufactured by Showa Denko Co., Ltd.) and dibutyltin dilaurate as a urethanization catalyst are appropriately added. Then, the reaction was carried out at 50 ° C. for 18 hours to obtain an ethylenically unsaturated group-containing acrylic resin [I] solution (solid content 35.5%, viscosity 1700 mPa · s / 25 ° C., acrylic resin [I]: weight. Average molecular weight (Mw) 520,000, dispersity (Mw / Mn) 4.95). The urethanization rate by MOI was 50 mol%, and the content of ethylenically unsaturated groups was 21.8 mmol / 100 g.

[Manufacturing of acrylic resins [II] to [VII] containing ethylenically unsaturated groups]
After obtaining the acrylic resins [II'] to [VII'], the same procedure was carried out according to the above-mentioned method for producing the acrylic resin [I'] except that the copolymer composition was as shown in Table 1. Further, according to the method for producing the acrylic resin [I], the MOI was reacted to obtain ethylenically unsaturated group-containing acrylic resins [II] to [VII].
The results of each measurement are shown in Table 1.
The ethylenically unsaturated group-containing acrylic resins [I] to [V] are acrylic resins used in the examples, and the ethylenically unsaturated group-containing acrylic resins [VI] and [VII] are comparative examples. It is an acrylic resin used for.

[Crosslinking agent (B)]
The following were prepared as the cross-linking agent (B-1).
-Coronate (registered trademark) L-55E (Adduct body of tolylene diisocyanate and trimethylolpropane, manufactured by Tosoh Corporation)

[Photopolymerization Initiator (C)]
The following photopolymerization initiators (C-1) were prepared.
Omnirad® 184 (1-hydroxycyclohexylphenylketone, manufactured by IGM RESINS)

<Examples 1 to 9, Comparative Examples 1 to 4>
An isocyanate-based cross-linking agent ("Coronate (registered trademark) L-55E" manufactured by Toso Co., Ltd. is applied to 100 parts of the ethylenically unsaturated group-containing acrylic resin ([I] to [VII]) prepared and prepared as described above. ”) Is added as shown in Table 2 below, and a part of a photopolymerization initiator (“Omnirad (registered trademark) 184” manufactured by IGM RESINS) is mixed, and this is mixed with ethyl acetate to obtain a solid content concentration (resin). Minutes) was adjusted to 30% by weight to obtain an active energy ray-curable release type pressure-sensitive adhesive composition solution.
The following pressure-sensitive adhesive sheet was prepared using the obtained active energy ray-curable release type pressure-sensitive adhesive composition solution, and the following evaluation was performed. The evaluation results are shown in Table 2 below.

<Adhesive sheet (S1) (for gel fraction measurement)>
The pressure-sensitive adhesive composition solution obtained above was applied to a heavy-release 38 μm polyester-based mold release sheet (Mitsui Chemicals Tocello Co., Ltd .: Lumirer (registered trademark) SP03-38BU) so that the thickness after drying was 25 μm. After drying at 100 ° C for 5 minutes, it is attached to a lightly peeled 38 μm polyester-based mold release sheet (Mitsui Chemicals Tosero Co., Ltd .: Lumirror (registered trademark) SP01-38BU) and aged in an environment of 40 ° C for 4 days. An adhesive sheet (S1) for measuring the gel fraction was obtained.

<Adhesive sheet (S2) (for measuring adhesive strength)>
The pressure-sensitive adhesive composition solution obtained above was applied to an untreated 38 μm polyester sheet (Mitsui Chemicals Tosero Co., Ltd .: Lumirer (registered trademark) T60) so that the thickness after drying was 25 μm, and 5 at 100 ° C. After drying for a minute, it is attached to a lightly peeled 38 μm polyester-based mold release sheet (Mitsui Chemicals Tocello Co., Ltd .: Lumirror (registered trademark) SP01-38BU) and aged for 4 days in an environment of 40 ° C. for adhesive strength measurement. Adhesive sheet (S2) was obtained.

[Gel fraction]
After cutting the adhesive sheet (S1) to 40 mm × 40 mm, the lightly peeled 38 μm polyester-based mold release sheet was peeled off, and the adhesive layer side was attached to a 50 mm × 100 mm SUS mesh sheet (200 mesh). Next, the heavy-release 38 μm polyester-based release sheet was peeled off and folded back from the center in the longitudinal direction of the SUS mesh sheet to wrap the sample. The gel was immersed in a sealed container containing 250 g of ethyl acetate for 24 hours, and the gel fraction was determined by the following formula from the weight change of the pressure-sensitive adhesive layer before and after the immersion in ethyl acetate.
Gel fraction (% by weight) = (weight (g) of pressure-sensitive adhesive layer after immersion in ethyl acetate
/ Weight of adhesive layer before immersion in ethyl acetate (g)) x 100

[Adhesive strength before irradiation with active energy rays]
A 25 mm × 100 mm test piece was prepared from the above adhesive sheet (S2), a lightly peeled 38 μm polyester release sheet was peeled off, and a stainless steel plate (SUS304BA plate) was placed on a stainless steel plate (SUS304BA plate) at 23 ° C. and a rubber weight of 2 kg under an atmosphere of 50% RH. The roller was reciprocated twice to apply pressure, and the mixture was left in the same atmosphere for 30 minutes, and then the peel strength (N / 25 mm) was measured at a peeling speed of 300 mm / min at 180 degrees.

[Adhesive strength after irradiation with active energy rays]
A 25 mm × 100 mm test piece was prepared from the above adhesive sheet (S2), a lightly peeled 38 μm polyester release sheet was peeled off, and a stainless steel plate (SUS304BA plate) was placed on a stainless steel plate (SUS304BA plate) at 23 ° C. and a rubber weight of 2 kg under an atmosphere of 50% RH. The roller was reciprocated twice to apply pressure, and the mixture was left in the same atmosphere for 30 minutes. Using one 80 W high-pressure mercury lamp, ultraviolet irradiation (cumulative irradiation amount 250 mJ / cm ² ) was applied from the untreated 38 μm polyester sheet side, and the mixture was allowed to stand for 30 minutes in an atmosphere of 23 ° C. and 50% RH, and then peeled off. 180 degree peel strength (N / 25 mm) was measured at a speed of 300 mm / min.

[Breaking elongation of the adhesive layer]
After laminating the pressure-sensitive adhesive layers until the thickness of the pressure-sensitive adhesive layer reaches 300 μm using the plurality of the above-mentioned pressure-sensitive adhesive sheets (S1), the adhesive layer is cut into 10 mm × 50 mm, and the integrated irradiation amount is 1000 mJ / cm using one 80 W high-pressure mercury lamp. After irradiating with the ultraviolet rays of No. ² and allowing it to stand for 30 minutes in an atmosphere of 23 ° C. and 50% RH, a heavy peeling 38 μm polyester-based mold release sheet was peeled off to obtain a test piece. For the test piece, measure the elongation at break at 23 ° C using a tensile tester (manufactured by Shimadzu Corporation, product name "Autograph AG-X") in accordance with JIS K71 61: 2014 by the following procedure. did.
Grasp both ends of the test piece in the length direction with a grip so that the length between the grips is 20 mm, and pull the test piece at a speed of 300 mm / min until the test piece breaks. The length (L mm) was measured and calculated from the following formula. The evaluation criteria are as follows.
Elongation at break (%) = [(length L of test piece when broken) / 20] × 100
(Evaluation criteria)
◎ ・ ・ ・ 150% or more ○ ・ ・ ・ 90% or more and less than 150% × ・ ・ ・ less than 90%

[Coefficient of variation]
First, an acrylic plate in which holes having a diameter of 1 mm and a depth of 24 ± 2 μm were patterned at intervals of 2.5 mm was used as an adherend. Next, a 25 mm × 120 mm test piece was prepared from the adhesive sheet (S2), a lightly peeled 38 μm polyester release sheet was peeled off, and a rubber having a weight of 2 kg was placed on the acrylic plate at 23 ° C. and 50% RH. The roller was reciprocated twice to apply pressure, and the mixture was left in the same atmosphere for 30 minutes. Ultraviolet irradiation (cumulative irradiation amount 250 mJ / cm ² ) was applied from the acrylic plate side using one 80 W high-pressure mercury lamp, and the mixture was allowed to stand for 30 minutes in an atmosphere of 23 ° C. and 50% RH. After that, in the measurement of the adhesive strength, the peeling strength (N / 25 mm) was 180 degrees at a peeling speed of 300 mm / min at 700 points at 0.05 mm intervals between the positions of 60 mm and 95 mm from the peeling start point. ) Was measured. The coefficient of variation was calculated from the following formula using the obtained 700 numerical values and evaluated as follows.
Coefficient of variation = (standard deviation of 700 points) / mean value of 700 points (evaluation standard)
○ ・ ・ ・ Less than 20 × ・ ・ ・ 20 or more

The pressure-sensitive adhesives of Examples 1 to 9 containing the ethylenically unsaturated group-containing acrylic resin (A) having an ethylenically unsaturated group-containing structural portion (α) in the side chain of the acrylic resin were before irradiation with active energy rays. The adhesive force after irradiation was lower than the adhesive force of the above, and the peelability (slight adhesiveness) was excellent. In addition, the pressure-sensitive adhesive after irradiation with active energy rays was flexible, had good elongation, and had a high elongation at break. Further, the coefficient of variation was small, and it had good peelability even for an adherend having irregularities.

On the other hand, the adhesives of Comparative Examples 1 to 4 having an ethylenically unsaturated group-containing structural portion on the side chain of the acrylic resin but having a small molecular weight of the ethylenically unsaturated group-containing structural moiety were peeled off after irradiation with active energy rays. The property (slight adhesiveness) was good, but the adhesive after irradiation with active energy rays had a low elongation at break. This does not satisfy the object of the present invention because there is a concern that adhesive residue may be generated at the time of peeling.
Further, in Comparative Example 1, the coefficient of variation is not satisfactory, and the peelability is not good.

The active energy ray-curable release type pressure-sensitive adhesive composition of the present invention is used for a temporary surface protection pressure-sensitive adhesive sheet for a substrate such as a metal plate or a plastic plate, or a semiconductor device such as a semiconductor wafer for a semiconductor manufacturing process such as a dicing process. It can be suitably used as an adhesive in a semiconductor fixing pressure-sensitive adhesive sheet used for attaching.

Claims (11)

Active energy ray curable characterized by containing an ethylenically unsaturated group-containing acrylic resin (A) having an ethylenically unsaturated group-containing structural site (α) having a number average molecular weight of 1,000 to 300,000 in the side chain. Peelable pressure-sensitive adhesive composition. The ethylenically unsaturated group-containing structural moiety (α) is a structural moiety derived from the hydroxyl group-containing macromonomer (α1), and the hydroxyl group derived from the hydroxyl group-containing macromonomer (α1) and the isocyanate group-containing ethylenically unsaturated compound (α2). ), The active energy ray-curable release type pressure-sensitive adhesive composition according to claim 1, wherein it is an ethylenically unsaturated group-containing structural moiety formed by a reaction with an isocyanate group. The active energy ray-curable release type pressure-sensitive adhesive composition according to claim 2, wherein the hydroxyl group-containing macromonomer (α1) has a weight average molecular weight of 1,000 to 300,000. The hydroxyl group-containing macromonomer (α1) has a structural moiety derived from the hydroxyl group-containing monomer, and the content of the structural moiety derived from the hydroxyl group-containing monomer in the hydroxyl group-containing macromonomer (α1) is 1 to 100% by weight. The active energy ray-curable release type pressure-sensitive adhesive composition according to claim 2 or 3. The active energy ray-curable peelable adhesive according to any one of claims 1 to 4, wherein the ethylenically unsaturated group-containing acrylic resin (A) has a structural portion derived from a hydroxyl group-containing monomer. Agent composition. The active energy according to any one of claims 1 to 5, wherein the content of the ethylenically unsaturated group in the ethylenically unsaturated group-containing acrylic resin (A) is 5 to 250 mmol / 100 g. A linearly curable release type pressure-sensitive adhesive composition. The active energy ray-curable release type pressure-sensitive adhesive composition according to any one of claims 1 to 6, further comprising a cross-linking agent (B). The active energy ray-curable release type pressure-sensitive adhesive composition according to any one of claims 1 to 7, further comprising a photopolymerization initiator (C). An active energy ray-curable release type pressure-sensitive adhesive sheet according to any one of claims 1 to 8, wherein the active energy ray-curable release type pressure-sensitive adhesive composition has a pressure-sensitive adhesive layer formed by cross-linking. .. The active energy ray-curable peelable pressure-sensitive adhesive sheet according to claim 9, wherein the pressure-sensitive adhesive layer is cured by irradiation with active energy rays and can be peeled off. An active energy ray-curable release type pressure-sensitive adhesive composition containing an ethylenically unsaturated group-containing acrylic resin, a cross-linking agent (B) and a photopolymerization initiator (C) is a pressure-sensitive adhesive having the following requirements [ An active energy ray-curable release type adhesive characterized by satisfying I].
[I] The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet having a cross-linked pressure-sensitive adhesive layer having a thickness of 300 μm was irradiated with ultraviolet rays having a cumulative irradiation amount of 1000 mJ / cm2 using one 80 W high-pressure mercury lamp, and the temperature was 23 ° C. After standing for 30 minutes in an atmosphere of 50% RH, the elongation at break measured by a tensile tester at a tensile speed of 300 mm / min is 90 to 300%.