Active energy ray curable release adhesive composition and release adhesive sheet

Abstract

To provide an active energy ray-curable releasable adhesive composition and a releasable adhesive sheet which have adhesive properties that can protect and fix a member to be processed with strong adhesive force during processing, can peel off the member to be processed with extremely low adhesive force and light force by active energy ray irradiation after processing and have stain resistance capable of peeling off the member to be processed without adhesive residue.SOLUTION: There is provided an active energy ray-curable releasable adhesive composition which comprises an acrylic resin (A) and an active energy ray-curable compound (B), wherein the acrylic resin (A) contains a structural unit derived from a carboxyl group-containing monomer (a2) and a structural unit derived from a hydroxyl group-containing monomer (a3), the ratio (a2) / (a3) by wt.% of the structural unit derived from a carboxyl group-containing monomer (a2) and the structural unit derived from a hydroxyl group-containing monomer (a3) is 10 to 150 and the active energy ray-curable compound (B) contains a urethane (meth)acrylate (b).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an active energy ray-curable release-type adhesive composition and a release-type adhesive sheet using the same, and more particularly, to an active energy ray-curable release-type adhesive composition used for an adhesive layer of a release-type adhesive sheet for temporary protection when processing a processed member such as a semiconductor wafer, a printed circuit board, a glass processed product, a metal plate, or a plastic plate, and a release-type adhesive sheet.

Background Art

[0002] Conventionally, a release-type adhesive sheet used in a process of separating various members such as electronic members and glass into individual pieces or a process of grinding to form a thin film is required to have a performance that can protect and fix the processed member from the stress applied during processing and can be easily peeled off after processing so as not to damage the separated or thinned member.

[0003] As such a release-type adhesive sheet, for example, Patent Document 1 discloses that by setting the storage elastic modulus and adhesive force of the adhesive layer before irradiation with energy rays within a specific range and enhancing the flexural resistance of the adhesive layer after irradiation with energy rays, a dicing sheet capable of achieving both low chip scattering during the dicing process and low substance residue in recesses can be obtained. Further, a dicing sheet obtained from an adhesive composition containing an acrylic polymer having a carboxyl group as a main component and an energy ray-polymerizable compound is disclosed. In addition, Patent Document 2 discloses a heat-resistant temporary adhesion sheet having an adhesive layer containing an acrylic polymer in which the mass ratio of a hydroxyl group-containing monomer to a carboxyl group-containing monomer is 51:49 to 100:0, an energy ray-polymerizable oligomer, and a specific polymerization initiator.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] The release-type adhesive sheets used in the above-mentioned electronic components and the like require strong adhesion to the workpiece to protect it from chipping and damage during cutting, due to the miniaturization of processing technology and the thinning of the workpiece. However, when it is time to remove them after their protective function is complete, they must be able to be removed with very little force and without leaving any adhesive residue on the workpiece.

[0006] However, in Patent Document 1, although the adhesive strength before active energy ray curing was excellent, the adhesive strength after active energy ray curing was high, making it difficult to peel the miniaturized and thinned workpiece from the adhesive sheet.

[0007] On the other hand, Patent Document 2 showed that the adhesive strength before energy ray curing was low, making chipping and damage to the material more likely, and therefore it could not be applied to miniaturized and thinned workpieces.

[0008] Against this background, the present invention aims to provide an active energy ray curable release adhesive composition and a release adhesive sheet that have adhesive properties that protect and fix the workpiece with strong adhesive force during processing, and after processing, have extremely low adhesive force due to active energy ray irradiation, can be peeled off with light force, and have stain resistance that can be peeled off from the workpiece without leaving any adhesive residue. [Means for solving the problem]

[0009] Generally, when a carboxyl group-containing acrylic resin is used in an active energy ray-curable release adhesive composition containing an acrylic resin and an active energy ray-curable compound, strong adhesive force is exhibited even before active energy ray irradiation. However, even after active energy ray curing, the adhesive force does not tend to decrease, making it difficult to peel off the processed material from miniaturized and thinned works. Therefore, the inventors have found that by adjusting the ratio of carboxyl groups to hydroxyl groups in the acrylic resin to a predetermined range, an active energy ray-curable release adhesive composition containing a carboxyl group-containing acrylic resin and an active energy ray-curable compound can be obtained that maintains its adhesive strength before active energy irradiation while exhibiting excellent stain resistance to the adhered surface during peeling after active energy irradiation.

[0010] In other words, the present invention An active energy ray curable release adhesive composition containing an acrylic resin (A) and an active energy ray curable compound (B), wherein the acrylic resin (A) is , a structural unit derived from (meth)acrylic monomer (a1), It contains structural units derived from a carboxyl group-containing monomer (a2) and structural units derived from a hydroxyl group-containing monomer (a3), The structural units derived from the (meth)acrylic monomer (a1) include structural units derived from n-butyl acrylate, and the content of structural units derived from the carboxyl group-containing monomer (a2) is 1 to 40% by weight and the content of structural units derived from the hydroxyl group-containing monomer (a3) ​​is 0.01 to 2% by weight relative to the total structural units constituting the acrylic resin (A), Structural units derived from carboxyl group-containing monomer (a2) and The aforementioned The weight percentage ratio of structural units derived from the hydroxyl group-containing monomer (a3) ​​(a2) / (a3) is 30 The gist of this invention is an active energy ray curable release adhesive composition characterized by having a coefficient of ~150, wherein the active energy ray curable compound (B) contains urethane (meth)acrylate (b), and the content of the active energy ray curable compound (B) is 75 to 120 parts by weight per 100 parts by weight of the acrylic resin (A). Furthermore, the present invention also provides a release-type adhesive sheet having an adhesive layer on which the above-mentioned active energy ray-curable release-type adhesive composition is crosslinked. [Effects of the Invention]

[0011] The active energy ray-curable release adhesive composition of the present invention can be used as a release adhesive sheet that exhibits excellent adhesive properties before and after active energy ray irradiation, as well as excellent stain resistance after release. [Modes for carrying out the invention]

[0012] The following describes specific embodiments for carrying out the present invention, but the present invention is not limited to these. In this invention, "(meth)acrylic" means acrylic or methacrylic, "(meth)acryloyl" means acryloyl or methacryloyl, and "(meth)acrylate" means acrylate or methacrylate. Furthermore, acrylic resins are resins obtained by polymerizing a polymerization component that contains at least one (meth)acrylate monomer. In this invention, the term "sheet" is not specifically distinguished from "film" or "tape," but rather encompasses all of these terms.

[0013] The active energy ray-curable release adhesive composition of the present invention is typically used in the adhesive layer of a release adhesive sheet that is intended to be peeled off after being bonded to a workpiece such as a metal plate, plastic plate, or semiconductor wafer. The release adhesive sheet is formed by coating the active energy ray-curable release adhesive composition onto a base sheet to form an adhesive layer, and after being bonded to a workpiece, the adhesive layer hardens and its adhesive strength decreases when irradiated with active energy rays, allowing it to be easily peeled off from the workpiece.

[0014] The active energy ray curable peelable adhesive composition of the present invention is described below. This is an active energy ray-curable release adhesive composition containing an acrylic resin (A) and an active energy ray-curable compound (B), wherein the acrylic resin (A) contains carboxyl groups and hydroxyl groups, the weight percentage ratio (a2) / (a3) of structural units derived from a carboxyl group-containing monomer (a2) to structural units derived from a hydroxyl group-containing monomer (a3) ​​is 10 to 150, and the active energy ray-curable compound (B) contains urethane (meth)acrylate (b). The following will explain things in order.

[0015] [Acrylic resin (A)] The acrylic resin (A) contains structural units derived from at least one (meth)acrylic monomer (a1). It is a resin obtained by polymerizing a polymerization component containing at least one (meth)acrylic monomer (a1). For example, an acrylic resin obtained by polymerizing a polymerization component containing a structural unit derived from the (meth)acrylic monomer (a1) as the main structure and optionally containing various other polymerizable monomers can be mentioned.

[0016] Note that "main component" for the (meth)acrylic monomer (a1) means that the structural unit derived from the (meth)acrylic monomer (a1) is usually contained at 40% by weight or more, preferably 50% by weight or more, more preferably 60% by weight or more based on the total structural units.

[0017] The acrylic resin (A) used in the present invention is obtained by polymerizing a copolymerization component (a) containing at least one (meth)acrylic monomer (a1), a carboxyl group-containing monomer (a2), and a hydroxyl group-containing monomer (a3).

[0018] [(Meth)acrylic monomer (a1)] Examples of the (meth)acrylic monomer (a1) (excluding (a2) and (a3)) used in the present invention include derivatives of (meth)acrylic acid, (meth)acrylamide or its derivatives, and the like.

[0019] Examples of the above-mentioned (meth)acrylic acid derivatives include alkyl group-containing (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, n-octadecyl (meth)acrylate, and the like.

[0020] Furthermore, other examples of derivatives of the above (meth)acrylic acid include, for example, cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; biphenyloxy structure-containing (meth)acrylates such as biphenyloxyethyl (meth)acrylate; 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate. Polycyclic (meth)acrylates such as acrylate and dicyclopentanyl (meth)acrylate; alkoxy group or phenoxy group-containing (meth)acrylates such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, methoxydiethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, alkylphenoxypolyethylene glycol (meth)acrylate; Epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate glycidyl ether; halogen-containing (meth)acrylates such as 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethyl ethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate; alkylaminoalkyl (meth)acrylates such as dimethylaminoethyl (meth)acrylate;Examples include oxetane group-containing (meth)acrylates such as 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, and 3-hexyl-oxetanylmethyl (meth)acrylate; and others.

[0021] Examples of derivatives of the above (meth)acrylamide include N-alkyl group-containing (meth)acrylamide derivatives such as N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, and N-hexyl(meth)acrylamide; N-hydroxyalkyl group-containing (meth)acrylamide derivatives such as N-methylol(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, and N-methylol-N-propane(meth)acrylamide; and aminomethyl(meth)acrylamide. Examples include N-aminoalkyl group-containing (meth)acrylamide derivatives such as amides and aminoethyl (meth)acrylamide; N-alkoxy group-containing (meth)acrylamide derivatives such as N-methoxymethyl (meth)acrylamide and N-ethoxymethyl (meth)acrylamide; N-mercaptoalkyl group-containing (meth)acrylamide derivatives such as mercaptomethyl (meth)acrylamide and mercaptoethyl (meth)acrylamide; and heterocyclic-containing (meth)acrylamide derivatives such as N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine.

[0022] These (meth)acrylic monomers (a1) may be used individually or in combination of two or more. Among these (meth)acrylic monomers, alkyl group-containing (meth)acrylates are preferably used. The number of carbon atoms in the alkyl group in alkyl group-containing (meth)acrylates is usually 1 to 20, preferably 2 to 18, and more preferably 4 to 12. Among these, methyl (meth)acrylate and n-butyl acrylate are preferred in terms of their stable adhesive properties and compatibility with urethane (meth)acrylates, which will be described later.

[0023] The content of structural units derived from (meth)acrylic monomer (a1) is 40% by weight of the total copolymer component (a), preferably 50% by weight or more, and more preferably 60% by weight or more. The upper limit is usually 100% by weight. In particular, when using alkyl group-containing (meth)acrylate, it is preferable that it be contained in an amount of 40% by weight or more, preferably 50% by weight or more, and more preferably 60% by weight or more, relative to the total copolymer component (a) of the acrylic resin (A). The upper limit is usually 100% by weight.

[0024] [Carboxyl group-containing monomer (a2)] Furthermore, examples of carboxyl group-containing monomers (a2) used in the present invention (excluding (meth)acrylic monomers (a1)) include (meth)acrylic acid, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, 2-acryloyloxyethyl phthalic acid, crotonic acid, maleic acid, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, and cinnamic acid. Among these, (meth)acrylic acid is preferred because it is easily copolymerized and its adhesive strength is easily improved before irradiation with active energy rays.

[0025] The content of structural units derived from the carboxyl group-containing monomer (a2) described above is preferably 1 to 40% by weight, more preferably 3 to 30% by weight, and even more preferably 5 to 25% by weight, relative to the total structural units constituting the acrylic resin (A), in order to easily increase the adhesive strength before irradiation with active energy rays.

[0026] If the content of structural units derived from the carboxyl group-containing monomer (a2) is too low, the adhesive strength before irradiation with active energy rays tends to be low, which can easily lead to chipping and breakage. Conversely, if the content is too high, the Tg of the acrylic resin tends to become too high, which tends to reduce adhesion and adhesive properties to the workpiece.

[0027] [Hydroxyl group-containing monomer (a3)] Examples of the hydroxyl group-containing monomer (a3) ​​include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate, as well as hydroxyl group-containing (meth)acrylates such as [4-(hydroxymethyl)cyclohexyl]methyl acrylate, cyclohexanedimethanol mono(meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate. Among these, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred because they are easily copolymerized, have good crosslinking properties with the crosslinking agents described later, and are good at improving stain resistance after irradiation with active energy rays.

[0028] The content of structural units derived from the above-mentioned hydroxyl group-containing monomer (a3) ​​is preferably 0.01 to 2% by weight, more preferably 0.02 to 1% by weight, and even more preferably 0.05 to 0.5% by weight, relative to the total structural units constituting the acrylic resin (A), from the viewpoint of improving adhesion to the substrate and stain resistance when peeling after irradiation with active energy rays. If the content of structural units derived from the hydroxyl group-containing monomer (a3) ​​is too low, adhesion to the substrate tends to decrease, and the cohesive force when forming the adhesive layer tends to decrease. Conversely, if the content is too high, the stability of the acrylic resin tends to decrease, and the pot life tends to be shortened.

[0029] [Other polymerizable monomers (a4)] The acrylic resin (A) used in the present invention may be a copolymer of polymerizable monomers other than (meth)acrylic monomers (a1), carboxyl group-containing monomers (a2), and hydroxyl group-containing monomers (a3) ​​(hereinafter referred to as "other polymerizable monomers (a4)"). Examples of the above-mentioned other polymerizable monomers (a4) include unsaturated carboxylic acids such as maleic anhydride, itaconic anhydride, and acrylamide-N-glycolic acid; vinyl carboxylate monomers such as vinyl acetate, vinyl propionate, vinyl stearate, and vinyl benzoate; monomers containing aromatic rings such as styrene and α-methylstyrene; and acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, alkyl vinyl ethers, vinyltoluene, vinylpyridine, vinylpyrrolidone, dialkyl itaconate, dialkyl fumarate, allyl alcohol, acrylic chloride, methyl vinyl ketone, allyltrimethylammonium chloride, and dimethylallyl vinyl ketone. These may be used individually or in combination of two or more.

[0030] Furthermore, the above-mentioned other polymerizable monomers (a4) may include photocrosslinkable monomers. Such photocrosslinkable monomers are those that generate radicals upon the action of light. As the above photocrosslinkable monomers, for example, (meth)acrylate monomers having a benzophenone structure such as 4-acryloyloxybenzophenone, 4-acryloyloxyethoxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'-methoxybenzophenone, 4-acryloyloxy-4'-bromobenzophenone, 4-acryloyloxyethoxy-4'-bromobenzophenone, 4-methacryloyloxybenzophenone, 4-methacryloyloxyethoxybenzophenone, 4-methacryloyloxy-4'-methoxybenzophenone, 4-methacryloyloxyethoxy-4'-methoxybenzophenone, 4-methacryloyloxy-4'-bromobenzophenone, 4-methacryloyloxyethoxy-4'-bromobenzophenone, and mixtures thereof may be used. By using such photocrosslinkable monomers as copolymer components, photocrosslinkable structural sites can be formed in the acrylic resin (A).

[0031] Furthermore, the content of structural units derived from other polymerizable monomers (a4) is preferably 0 to 30% by weight, more preferably 0 to 20% by weight, relative to the total structural units constituting the acrylic resin (A). Among the structural units derived from other polymerizable monomers (a4), it is preferable that the structural units derived from photocrosslinkable monomers be present in an amount of 0 to 10% by weight, preferably 0 to 5% by weight, relative to the total structural units constituting the acrylic resin (A).

[0032] [Method for producing acrylic resin (A)] Conventional known methods such as solution radical polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization can be used as polymerization methods for the acrylic resin (A) used in the present invention. For example, one method involves mixing or dropping a polymerization component and a thermal polymerization initiator, which are appropriately selected, into an organic solvent and polymerization under predetermined polymerization conditions. Among these, solution radical polymerization and bulk polymerization are preferred, and solution radical polymerization is particularly preferred because it provides a stable acrylic resin. The following is an example of a preferred method for producing the acrylic resin (A) used in the present invention.

[0033] First, the copolymerization components and thermal polymerization initiator are mixed or added dropwise to an organic solvent, and an acrylic resin solution is obtained by solution polymerization.

[0034] (Organic solvents) Examples of organic solvents 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, aliphatic alcohols such as N-propyl alcohol and isopropyl alcohol, and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. These can be used individually or in combination of two or more. Among these solvents, it is preferable to use an organic solvent with a boiling point of 80°C or lower, as this allows for efficient production of a solvent-free acrylic resin by distilling off the solvent from the acrylic resin solution obtained by solution polymerization.

[0035] Examples of organic solvents with a boiling point of 80°C or lower include hydrocarbon solvents such as n-hexane (67°C), alcohol solvents such as methanol (65°C), ester solvents such as ethyl acetate (77°C) and methyl acetate (54°C), ketone solvents such as methyl ethyl ketone (80°C) and acetone (56°C), diethyl ether (35°C), methylene chloride (40°C), and tetrahydrofuran (66°C). Among these, ethyl acetate, acetone, and methyl acetate are preferred in terms of versatility and safety, and ethyl acetate and acetone are particularly preferred. The numbers in parentheses following each organic solvent name indicate the boiling point of that solvent.

[0036] (Thermal polymerization initiator) As thermal polymerization initiators used in the above polymerization reaction, ordinary radical polymerization initiators such as azo polymerization initiators and peroxide polymerization initiators can be used. Examples of azo polymerization initiators include 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, (1-phenylethyl)azodiphenylmethane, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), and 2 Examples of peroxide polymerization initiators include 2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), and peroxide polymerization initiators include, for example, benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, lauroyl peroxide, t-butyl peroxypivalate, t-hexyl peroxypivalate, t-hexyl peroxyneodecanoate, diisopropyl peroxycarbonate, and diisobutyryl peroxide. These can be used individually or in combination of two or more.

[0037] The amount of thermal polymerization initiator used is typically 0.001 to 10% by weight, preferably 0.1 to 8% by weight, particularly preferably 0.5 to 6% by weight, even more preferably 1 to 4% by weight, especially preferably 1.5 to 3% by weight, and most preferably 2 to 2.5% by weight, based on 100% by weight of the polymerization component. If the amount of thermal polymerization initiator used is too small, the polymerization rate of the acrylic resin decreases, the residual monomers increase, and the weight-average molecular weight of the acrylic resin tends to increase. If the amount used is too large, the time required for the final heating described later becomes long and unproductive.

[0038] (Polymerization conditions, etc.) For solution polymerization, polymerization can be carried out according to conventionally known polymerization conditions. For example, polymerization can be carried out by mixing or dropping polymerization components and a thermal polymerization initiator into a solvent and polymerization under predetermined polymerization conditions.

[0039] The polymerization temperature in the above polymerization reaction is usually 40 to 120°C, but in the present invention, 50 to 90°C is preferred, particularly 55 to 75°C, and even more preferably 60 to 70°C, from the viewpoint of stable reaction. If the polymerization temperature is too high, the acrylic resin tends to gel easily, and if it is too low, the activity of the thermal polymerization initiator decreases, so the polymerization rate tends to decrease and the amount of residual monomer increases.

[0040] Furthermore, there are no particular restrictions on the polymerization time in the polymerization reaction (or the time until the start of the final heating, if the final heating described later is performed), but it is preferably 0.5 hours or more from the addition of the last thermal polymerization initiator, particularly preferably 1 hour or more, even more preferably 2 hours or more, and especially preferably 5 hours or more. The upper limit for the polymerization time is usually 72 hours. Furthermore, the polymerization reaction is preferably carried out while refluxing the solvent, as this facilitates heat removal.

[0041] In the production of the above-mentioned acrylic resin, it is preferable to decompose the thermal polymerization initiator by heating in a final heating process in order to reduce the amount of residual thermal radical initiator.

[0042] The final heating temperature is preferably higher than the 10-hour half-life temperature of the thermal polymerization initiator. Specifically, it is usually 40 to 150°C, preferably 55 to 130°C from the viewpoint of suppressing gelation, and particularly preferably 75 to 95°C. If the final heating temperature is too high, the acrylic resin tends to yellow, and if it is too low, polymerization components and thermal polymerization initiators remain, which tends to reduce the temporal stability and thermal stability of the acrylic resin. Thus, an acrylic resin solution can be obtained.

[0043] [Physical properties of acrylic resin (A)] The weight-average molecular weight (Mw) of the acrylic resin (A) obtained as described above is preferably 50,000 or more, more preferably 100,000 to 2,000,000, more preferably 200,000 to 1,500,000, and especially preferably 400,000 to 1,000,000. If the weight-average molecular weight is too low, the cohesive force of the resulting adhesive layer decreases, and the adhesive properties before active energy ray curing and the stain resistance after active energy ray irradiation tend to decrease. On the other hand, if the weight-average molecular weight is too high, the compatibility with urethane (meth)acrylate described later tends to decrease, and the adhesive strength before active energy ray irradiation tends to decrease.

[0044] Furthermore, the degree of dispersion of the acrylic resin (A) [weight-average molecular weight (Mw) / number-average molecular weight (Mn)] is preferably 10 or less, and more preferably 7 or less. If the degree of dispersion is too high, the cohesive force tends to decrease. The lower limit of the degree of dispersion is usually 1.

[0045] The weight-average molecular weight of acrylic resin (A) is the weight-average molecular weight converted to the standard polystyrene molecular weight. This can be measured using a high-performance liquid chromatograph (Waters Japan Co., Ltd., "Waters2695 (main unit)" and "Waters2414 (detector)") with three ShodexGPCKF-806L columns (exclusion limit molecular weight: 2 × 10⁷, separation range: 100 to 2 × 10⁷, theoretical plates: 10,000 stages / column, packing material: styrene-divinylbenzene copolymer, packing particle size: 10 μm) connected in series. The number-average molecular weight can be measured in a similar manner. The degree of dispersion can be determined from the measured weight-average molecular weight and number-average molecular weight.

[0046] The glass transition temperature (Tg) of the acrylic resin (A) is preferably 20°C or lower, more preferably -70°C to 0°C, even more preferably -65°C to -10°C, and particularly preferably -60°C to -20°C. If the glass transition temperature is too low, the cohesive force of the adhesive layer decreases and the adhesive properties before irradiation with active energy rays tend to deteriorate. If it is too high, the adhesion to the workpiece tends to decrease and the adhesive properties tend to deteriorate.

[0047] The glass transition temperature is calculated using Fox's formula, which is shown below. TIFF0007859101000001.tif37150Tg: Glass transition temperature (K) of polymers Tga: Glass transition temperature of the homopolymer of monomer A (K) Wa: Weight fraction of monomer A Tgb: Glass transition temperature (K) of the monomer B homopolymer. Wb: Weight fraction of monomer B. Tgn: Glass transition temperature of monomer N homopolymer (K) Wn: Weight fraction of monomer N (Wa + Wb + ... + Wn = 1)

[0048] In other words, these are values ​​calculated by applying Fox's formula to the glass transition temperature and weight fraction of each monomer constituting the acrylic resin when they are homopolymers. The glass transition temperature of the monomers constituting the acrylic resin, when formed into a homopolymer, is usually measured using a differential scanning calorimeter (DSC), and can be measured according to methods compliant with JIS K7121-1987 or JIS K6240.

[0049] The refractive index of acrylic resin (A) is typically 1.440 to 1.600. A refractive index such that minimizes the refractive index difference with the laminated workpiece is preferable because it reduces light loss at the interface between the workpieces.

[0050] The refractive index mentioned above was measured using a refractive index measuring device (Abe Refractometer 1T, manufactured by Atago Corporation) with NaD radiation at 23°C on a thin film of acrylic resin (A).

[0051] [Activated energy ray-curable compound (B)] The active energy ray curable compound (B) used in the present invention contains a urethane (meth)acrylate compound (b). It may also contain monofunctional (meth)acrylates, polyfunctional (meth)acrylates, etc.

[0052] The above-mentioned urethane (meth)acrylate compound (b) may be urethane (meth)acrylate compound (b-1), which is a reaction product of a hydroxyl group-containing (meth)acrylate compound (b1) and a polyvalent isocyanate compound (b2); urethane (meth)acrylate compound (b-2), which is a reaction product of a hydroxyl group-containing (meth)acrylate compound (b1), a polyvalent isocyanate compound (b2), and a polyol compound (b3); or urethane (meth)acrylate compound (b-3), which is a reaction product of a hydroxyl group-containing (meth)acrylate compound (b1), a polyvalent isocyanate compound (b2), a monofunctional alcohol (b4), and optionally a polyol compound (b3).

[0053] In particular, in the present invention, it is preferable that the urethane (meth)acrylate compound (b-1), which is a reaction product of a hydroxyl group-containing (meth)acrylate compound (b1) and a polyvalent isocyanate compound (b2), or the urethane (meth)acrylate compound (b-2), which is a reaction product of a hydroxyl group-containing (meth)acrylate compound (b1), a polyvalent isocyanate compound (b2), and a polyol compound (b3), be readily compatible with the acrylic resin (A) and have good adhesive properties and stain resistance before and after irradiation with active energy rays. In this invention, only one type of urethane (meth)acrylate compound (b) may be used, or two or more types may be used in combination.

[0054] The above hydroxyl group-containing (meth)acrylate compound (b1) is preferably one having one hydroxyl group, for example, 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)acrylate Examples include hydroxyl group-containing (meth)acrylate compounds containing one ethylenically unsaturated group, such as kryloyloxypropyl (meth)acrylate; hydroxyl group-containing (meth)acrylate compounds containing two ethylenically unsaturated groups, such as glycerin di(meth)acrylate and 2-hydroxy-3-acryloyloxypropyl methacrylate; and hydroxyl group-containing (meth)acrylate compounds containing three or more ethylenically unsaturated groups, such as 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, and ethylene oxide-modified dipentaerythritol penta(meth)acrylate. These hydroxyl group-containing (meth)acrylate compounds (b) can be used individually or in combination of two or more.

[0055] Of the above hydroxyl group-containing (meth)acrylate compounds (b), those containing three or more ethylenically unsaturated groups are preferred due to their excellent reactivity and versatility, pentaerythritol tri(meth)acrylate and dipentaerythritol penta(meth)acrylate are more preferred, and pentaerythritol tri(meth)acrylate is even more preferred.

[0056] Examples of the above polyvalent isocyanate compounds (b2) include aromatic polyvalent isocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate; and aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, and lysine triisocyanate. Examples include cyanates; alicyclic polyvalent isocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate; or isocyanurates or polymer compounds of these polyvalent isocyanates, allophanate-type polyisocyanates, burette-type polyisocyanates, and water-dispersible polyisocyanates (for example, "Aquanate 100", "Aquanate 110", "Aquanate 200", "Aquanate 210", etc. manufactured by Nippon Polyurethane Industries Co., Ltd.).

[0057] Among these, aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate, and alicyclic diisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and norbornene diisocyanate are preferred due to their excellent reactivity and versatility. Particularly preferred are isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, and hexamethylene diisocyanate, and even more preferred are isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate.

[0058] The polyol compound (b3) mentioned above can be any compound containing two or more hydroxyl groups, such as aliphatic polyols, alicyclic polyols, polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, polybutadiene polyols, polyisoprene polyols, (meth)acrylic polyols, and polysiloxane polyols. These can be used individually or in combination of two or more.

[0059] Examples of the above aliphatic polyols include 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-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 1,5-pentamethylenediol, 1, Examples include aliphatic alcohols containing two hydroxyl groups, such as 6-hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, pentaerythritol diacrylate, 1,9-nonanediol, and 2-methyl-1,8-octanediol; sugar alcohols such as xylitol and sorbitol; and aliphatic alcohols containing three or more hydroxyl groups, such as glycerin, trimethylolpropane, and trimethylolethane.

[0060] Examples of the above-mentioned alicyclic polyols include cyclohexanediols such as 1,4-cyclohexanediol and cyclohexyldimethanol, hydrogenated bisphenols such as hydrogenated bisphenol A, and tricyclodecanedimethanol.

[0061] Examples of the polyether-based polyols mentioned above include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, polypentamethylene glycol, and polyhexamethylene glycol, as well as random or block copolymers of these polyalkylene glycols.

[0062] Examples of the above-mentioned polyester polyols include condensation polymers of polyhydric alcohols and polyhydric carboxylic acids; ring-opening polymers of cyclic esters (lactones); and reaction products of three components: polyhydric alcohols, polyhydric carboxylic acids, and cyclic esters.

[0063] Examples of the polyhydric alcohols mentioned above include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 1,5-pentamethylenediol, neopentyl glycol, 1,6-hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, glycerin, trimethylolpropane, trimethylolethane, cyclohexanediols (such as 1,4-cyclohexanediol), bisphenols (such as bisphenol A), and sugar alcohols (such as xylitol and sorbitol). Examples of the polycarboxylic acids mentioned above include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedionic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, and trimellitic acid. Examples of the cyclic esters mentioned above include propiolactone, β-methyl-δ-valerolactone, and ε-caprolactone.

[0064] Examples of the polycarbonate-based polyols mentioned above include reaction products of polyhydric alcohols and phosgene; and ring-opening polymers of cyclic carbonate esters (such as alkylene carbonates). Examples of the polyhydric alcohols mentioned above include the polyhydric alcohols exemplified in the description of polyester-based polyols, and examples of the alkylene carbonates include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, and hexamethylene carbonate. Note that the polycarbonate-based polyols are any compounds having a carbonate bond in the molecule and a hydroxyl group at the end, and may also have an ester bond in addition to the carbonate bond.

[0065] Examples of the above-mentioned polyolefin-based polyols include those having a homopolymer or copolymer of ethylene, propylene, butene, etc. as a saturated hydrocarbon backbone, and having hydroxyl groups at the molecular ends.

[0066] Examples of the polybutadiene-based polyols mentioned above include those having a butadiene copolymer as the hydrocarbon backbone and having hydroxyl groups at the molecular ends. The polybutadiene-based polyol may also be a hydrogenated polybutadiene polyol in which all or some of the ethylenically unsaturated groups contained in its structure are hydrogenated.

[0067] Examples of the above-mentioned polyisoprene polyols include those having an isoprene copolymer as a hydrocarbon backbone and having hydroxyl groups at their molecular ends. The polyisoprene polyol may also be a hydrogenated polyisoprene polyol in which all or some of the ethylenically unsaturated groups contained in its structure are hydrogenated.

[0068] Examples of the above-mentioned (meth)acrylic polyols include polymers or copolymers of (meth)acrylic acid esters that have at least two hydroxyl groups in the molecule. Examples of such (meth)acrylic acid esters include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate.

[0069] Examples of the polysiloxane-based polyols mentioned above include dimethylpolysiloxane polyol and methylphenylpolysiloxane polyol.

[0070] Among these, aliphatic polyols and alicyclic polyols are preferred in terms of cost, while polyester polyols, polyether polyols, and polycarbonate polyols are preferred in terms of versatility.

[0071] The weight-average molecular weight of the polyol compound (b3) is preferably 60 to 10,000, particularly preferably 100 to 5,000, and even more preferably 200 to 4,000. If the weight-average molecular weight of the polyol compound (b3) is too high, the compatibility between the resulting urethane (meth)acrylate compound (b) and the acrylic resin (A) tends to decrease, and the adhesive properties after irradiation with active energy rays tend to decrease.

[0072] The above monofunctional alcohol (b4) is not particularly limited, but examples include alcohols containing linear or branched alkyl groups having 1 to 36 carbon atoms, aromatic rings, alicyclic groups, heterocyclic groups, etc. Preferably, from the viewpoint of versatility, it is an alcohol containing linear or branched alkyl groups having 1 to 36 carbon atoms, and more preferably, it is an alcohol containing linear or branched alkyl groups having 4 to 18 carbon atoms. These can be used individually or in combination of two or more.

[0073] The urethane (meth)acrylate compound (b) can be produced by reacting the above components using known reaction methods. The following is an example. (1) When obtaining a urethane (meth)acrylate compound (b) A method for urethane reaction between the above-mentioned hydroxyl group-containing (meth)acrylate compound (b) and a polyhydric isocyanate compound (b2). (2) When obtaining a urethane (meth)acrylate compound (b-2) A method for urethane formation by reacting the above-mentioned hydroxyl group-containing (meth)acrylate compound (b), a polyvalent isocyanate compound (b2), and a polyol compound (b3). (3) When obtaining a urethane (meth)acrylate compound (b-3) A method for urethane reaction involving the above-mentioned hydroxyl group-containing (meth)acrylate compound (b), a polyhydric isocyanate compound (b2), a polyol compound (b3), and a monofunctional alcohol (b4). The above urethane formation reaction can be carried out by charging the above components into a reactor all at once or separately and performing the urethane formation reaction using known reaction methods. Furthermore, when producing urethane (meth)acrylate compounds (b-2) or urethane (meth)acrylate compounds (b-3), a method in which a hydroxyl group-containing (meth)acrylate compound (b) or monofunctional alcohol (b4) is reacted with a reaction product obtained by first reacting a polyol compound (b3) with a polyvalent isocyanate compound (b2) is useful in terms of the stability of the urethane formation reaction and the reduction of by-products.

[0074] In the reaction between the above-mentioned hydroxyl group-containing (meth)acrylate compound (b) and the polyvalent isocyanate compound (b2), it is preferable to use a reaction catalyst to accelerate the reaction. Examples of such reaction catalysts include organometallic compounds such as dibutyltin dilaurate, trimethyltin hydroxide, and tetra-n-butyltin; metal salts such as zinc octoteate, tin octoteate, tin octoate, cobalt naphthenate, stannous chloride, and stannous chloride; amine 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 other dibutyltin. Examples of catalysts include bismuth-based catalysts such as organic bismuth compounds like dioctyl bismuth dilaurate and dioctyl bismuth dilaurate, and organic acid bismuth salts such as bismuth 2-ethylhexanoate, bismuth naphthenate, bismuth isodecanate, bismuth neodecanoate, bismuth laurate, bismuth maleate, bismuth stearate, bismuth oleate, bismuth linoleate, bismuth acetate, bismuth lybisneodecanoate, bismuth disalicylate, and bismuth digallate; zirconium-based catalysts such as inorganic zirconium, organozirconium, and elemental zirconium; and catalysts used in combination with two or more other catalysts such as zinc 2-ethylhexanoate / zirconium tetraacetylacetonate. Among these, dibutyltin dilaurate and organic bismuth compounds are preferred. These catalysts can be used individually or in combination of two or more.

[0075] In the above urethane 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 aromatics like toluene and xylene.

[0076] Furthermore, the reaction temperature for the above urethane formation reaction is usually 30 to 90°C, preferably 40 to 80°C, and the reaction time is usually 2 to 10 hours, preferably 3 to 8 hours.

[0077] The above urethane formation reaction is terminated when the residual isocyanate group content in the reaction system becomes 0.5% by weight or less, thereby yielding a urethane (meth)acrylate compound (b).

[0078] The concentration of (meth)acryloyl groups in the urethane (meth)acrylate compound (b) obtained in this way is 0.5 mmol / g or more. Preferably it is 1.0 to 35 mmol / g, more preferably 1.5 to 20 mmol / g, and particularly preferably 2.0 to 15 mmol / g. By setting the concentration of (meth)acryloyl groups in the urethane (meth)acrylate compound (b) within the above range, excellent peelability after irradiation with active energy rays can be achieved.

[0079] Furthermore, the urethane (meth)acrylate compound (b) described above preferably has three or more ethylenically unsaturated groups, from the viewpoint of adhesive properties after irradiation with active energy rays. If the number of such ethylenically unsaturated groups is too small, a sufficient crosslinking density cannot be obtained, and the adhesive properties and stain resistance after irradiation with active energy rays tend to decrease.

[0080] The weight-average molecular weight of the above-mentioned urethane (meth)acrylate compound (b) is typically 200 to 10,000, preferably 400 to 5,000, and more preferably 600 to 4,000. If the weight-average molecular weight is too high, the active energy ray curable compound (B) and the acrylic resin (A) become difficult to mix uniformly, and the adhesive properties before and after active energy ray irradiation tend to decrease. If the weight-average molecular weight is too low, the cohesive force of the adhesive layer tends to decrease, and the adhesive properties tend to decrease.

[0081] The weight-average molecular weight mentioned above is the weight-average molecular weight converted to the standard polystyrene molecular weight, and is measured using a high-performance liquid chromatograph (Waters, "ACQUITYAPC system") with four columns in series: one ACQUITYAPCXT450, one ACQUITYAPCXT200, and two ACQUITYAPCXT45.

[0082] The viscosity of the urethane (meth)acrylate compound (b) used in the present invention at 60°C is preferably 50 to 10,000 mPa·s, more preferably 100 to 7,000 mPa·s, and particularly preferably 200 to 4,000 mPa·s. If the viscosity is too low, the cohesive force tends to decrease, and if it is too high, the coating properties tend to decrease. The viscosity can be measured using an E-type viscometer.

[0083] Furthermore, the active energy ray curable compound (B) may also contain monofunctional (meth)acrylates or polyfunctional (meth)acrylates.

[0084] [Monofunctional (meth)acrylate] Examples of such monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, acrylonitrile, 2-methoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-phenoxy-2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, glycerin mono(meth)acrylate, glycidyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyl Oxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)-methyl (meth)acrylate, cyclohexanespiro-2-(1,3-dioxolan-4-yl)-methyl (meth)acrylate, 3-ethyl-3-oxetanylmethyl (meth)acrylate, γ-butyrolactone (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, n-stearyl (meth)acrylate, benzyl (meth)acrylate, phenolethylene oxide modified (n=2) (meth)acrylate, nonylphenol propylene oxide modified (n=2)5) Examples include (meth)acrylate monomers such as (meth)acrylate, 2-(meth)acryloyloxyethyl acid phosphate, 2-(meth)acryloyloxy-2-hydroxypropyl phthalate, half-(meth)acrylate, furfuryl(meth)acrylate, tetrahydrofurfuryl(meth)acrylate, carbitol(meth)acrylate, benzyl(meth)acrylate, butoxyethyl(meth)acrylate, allyl(meth)acrylate, (meth)acryloylmorpholine, polyoxyethylene secondary alkyl ether acrylate, 2-hydroxyethylacrylamide, N-methylol(meth)acrylamide, N-vinylpyrrolidone, 2-vinylpyridine, and vinyl acetate.

[0085] [Multifunctional (meth)acrylate] Examples of polyfunctional (meth)acrylates include difunctional (meth)acrylates and acrylates with three or more functions. Examples of difunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide-modified bisphenol A type di(meth)acrylate, propylene oxide-modified bisphenol A type di(meth)acrylate, and cyclohexanedimethanol di(meth)acrylate. Examples include acrylates, ethoxylated cyclohexanedimethanol di(meth)acrylate, methylol dicyclopentane di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, diglycidyl phthalate di(meth)acrylate, hydroxypivalic acid-modified neopentyl glycol di(meth)acrylate, and isocyanurate-modified ethylene oxide diacrylate.

[0086] Examples of acrylates with three or more functions include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tri(meth)acryloyloxyethoxytrimethylolpropane, glycerin polyglycidyl ether poly(meth)acrylate, isocyanurate ethylene oxide modified triacrylate, caprolactone modified dipentaerythritol penta(meth)acrylate, and cap Examples include loractone-modified dipentaerythritol hexa(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, caprolactone-modified pentaerythritol tetra(meth)acrylate, ethylene oxide-modified dipentaerythritol penta(meth)acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tetra(meth)acrylate, and ethoxylated 15-glycerin triacrylate.

[0087] In addition, Michael adducts of acrylic acid or 2-acryloyloxyethyl dicarboxylic acid monoesters can also be used in combination. Examples of such Michael adducts of acrylic acid include (meth)acrylate dimers, (meth)acrylate trimers, and (meth)acrylate tetramers. The above-mentioned 2-acryloyloxyethyl dicarboxylic acid monoester is a carboxylic acid having a specific substituent, and examples include 2-acryloyloxyethyl succinate monoester, 2-methacryloyloxyethyl succinate monoester, 2-acryloyloxyethyl phthalate monoester, 2-methacryloyloxyethyl phthalate monoester, 2-acryloyloxyethyl hexahydrophthalate monoester, and 2-methacryloyloxyethyl hexahydrophthalate monoester. Furthermore, other examples include oligoester acrylates. These monofunctional (meth)acrylates and polyfunctional (meth)acrylates can be used individually or in combination of two or more types.

[0088] The content of the urethane (meth)acrylate compound (b) in the active energy ray curable compound (B) is 50% by weight or more, preferably 80% by weight or more, with an upper limit of 100% by weight. If the content is too low, the adhesive properties and stain resistance after irradiation with active energy rays tend to decrease.

[0089] The content of monofunctional (meth)acrylates and polyfunctional (meth)acrylates other than the urethane (meth)acrylate compound (b) in the active energy ray curable compound (B) is less than 50% by weight, preferably less than 20% by weight, with a lower limit of 0% by weight. If the content is too high, the adhesive properties and stain resistance tend to decrease after irradiation with active energy rays.

[0090] In the active energy ray curable adhesive composition of the present invention, the content of the active energy ray curable compound (B) is 10 to 200% by weight per 100 parts by weight of the acrylic resin (A). Preferably, it is 30 to 180 parts by weight, more preferably 50 to 150 parts by weight, and even more preferably 75 to 120 parts by weight. If the content of the active energy ray curable compound (B) is too low, the peelability after irradiation with active energy rays tends to decrease, and if it is too high, the cohesive force of the adhesive layer tends to decrease, and the adhesive properties before and after irradiation with active energy rays tend to decrease.

[0091] [Crosslinking agent (C)] The active energy ray-curable release adhesive composition of the present invention may further contain a crosslinking agent (C). Examples of crosslinking agents (C) include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, oxazoline-based crosslinking agents, melamine-based crosslinking agents, aldehyde-based crosslinking agents, and amine-based crosslinking agents. Among these, isocyanate-based crosslinking agents are preferred in terms of improving the adhesion of the release adhesive sheet to the base sheet and their reactivity with the acrylic resin (A). Furthermore, these crosslinking agents (C) may be used alone or in combination of two or more types.

[0092] Examples of the above-mentioned isocyanate-based crosslinking agents include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hexamethylene diisocyanate, diphenylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, and adduct compounds of these polyisocyanate compounds with polyol compounds such as trimethylolpropane, as well as burette and isocyanurate compounds of these polyisocyanate compounds. Among these, isocyanurates of hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, adducts of 2,6-tolylene diisocyanate and trimethylolpropane, isocyanurates of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, and adducts of tetramethylxylylene diisocyanate and trimethylolpropane are preferred in terms of drug resistance and reactivity with functional groups.

[0093] Examples of the epoxy crosslinking agents mentioned above include bisphenol A-epichlorohydrin type epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidylerythritol, diglycerol polyglycidyl ether, 1,3'-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-m-xylenediamine.

[0094] Examples of the above-mentioned aziridine crosslinking agents include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinylcarboxyamide), and N,N'-hexamethylene-1,6-bis(1-aziridinylcarboxyamide).

[0095] Examples of the above oxazoline crosslinking agents include 2,2'-bis(2-oxazoline), 1,2-bis(2-oxazoline-2-yl)ethane, 1,4-bis(2-oxazoline-2-yl)butane, 1,8-bis(2-oxazoline-2-yl)butane, 1,4-bis(2-oxazoline-2-yl)cyclohexane, 1,2-bis(2-oxazoline-2-yl)benzene, and 1,3-bis(2-oxazoline-2-yl). Examples include bisoxazoline compounds containing aliphatic or aromatic compounds such as benzene, and polymers of one or more addition polymerizable oxazolines such as 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, and 2-isopropenyl-5-ethyl-2-oxazoline.

[0096] Examples of the melamine-based crosslinking agents mentioned above include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexapoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, and melamine resin.

[0097] Examples of the aldehyde-based crosslinking agents mentioned above include glyoxal, malondialdehyde, succinidaldehyde, maleidaldehyde, glutardialdehyde, formaldehyde, acetaldehyde, and benzaldehyde.

[0098] Examples of the amine-based crosslinking agents mentioned above include hexamethylenediamine, triethyldiamine, polyethyleneimine, hexamethylenetetraamine, diethylenetriamine, triethyltetraamine, isophoronediamine, amino resins, and polyamides.

[0099] The content of the crosslinking agent (C) is usually preferably 0.1 to 30 parts by weight, particularly preferably 0.2 to 20 parts by weight, and even more preferably 0.3 to 15% by weight, per 100 parts by weight of the acrylic resin (A). If the amount of crosslinking agent (C) is too small, the cohesive force of the adhesive layer decreases, and the adhesive properties tend to deteriorate. If the amount of crosslinking agent (C) is too large, the adhesive properties before irradiation with active energy rays deteriorate, and lifting and peeling tend to occur during processing.

[0100] [Photopolymerization initiator (D)] The photopolymerization initiator (D) used in this invention can be any agent that generates radicals upon the action of light. Note that if the (meth)acrylic resin contains a photocrosslinkable monomer, it is not necessary to include a photopolymerization initiator. Examples of such photopolymerization initiators (D) include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexylphenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, and 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one. Acetophenones such as 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone and 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone oligomer; benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; benzophenone, o-benzoyl methyl benzoate, 4-phenylbenzophenone, and 4-benzoyl-4'-methyl-diphenyl sulfide Benzophenones such as 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyloxy)ethyl]benzenemethanaminonium bromide, (4-benzoylbenzyl)trimethylammonium chloride; 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1 Examples include thioxanthones such as chloro-4-propoxythioxanthone and 2-(3-dimethylamino-2-hydroxy)-3,4-dimethyl-9H-thioxanthone-9-one mesochloride; and acyl phosphonate oxides such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.Among these, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, and 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one are preferred because they do not sublimate when heated and are stable. These photopolymerization initiators (D) can be used alone or in combination of two or more.

[0101] Furthermore, as auxiliary agents for these photopolymerization initiators (D), for example, triethanolamine, triisopropanolamine, and 4,4'-dimethylaminobenzophenone (Michler ketone) are used. It is also possible to use in combination with 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, ethyl 4-dimethylaminobenzoate, (n-butoxy)ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, etc. These auxiliary agents can also be used alone or in combination of two or more.

[0102] The content of the photopolymerization initiator (D) is preferably 0.1 to 20 parts by weight, particularly preferably 0.5 to 15 parts by weight, and especially preferably 1 to 10 parts by weight, per 100 parts by weight of the active energy ray curable compound (B). If the content of the photopolymerization initiator (D) is too low, the peelability after irradiation with active energy rays tends to decrease, and if it is too high, the stain resistance of the workpiece tends to decrease after irradiation with active energy rays.

[0103] [Other ingredients] The active energy ray-curable release adhesive composition of the present invention may further contain small amounts of additives such as monofunctional monomers, antistatic agents, antioxidants, plasticizers, fillers, pigments, diluents, anti-aging agents, UV absorbers, and UV stabilizers, to the extent that they do not impair the effects of the present invention. These additives can be used individually or in combination of two or more. Antioxidants, in particular, are effective in maintaining the stability of the adhesive layer. There are no particular restrictions on the amount of antioxidants that can be added, but it is preferably 0.01 to 5% by weight relative to the active energy ray-curable release adhesive composition. In addition to the above-mentioned additives, the active energy ray-curable release adhesive composition of the present invention may also contain small amounts of impurities contained in the raw materials for the production of the components of the active energy ray-curable release adhesive composition.

[0104] Furthermore, the active energy ray-curable peelable adhesive composition of the present invention preferably does not contain tackifying resins such as terpene resins, rosin resins, chroman resins, phenolic resins, styrene resins, or petroleum resins, as this reduces the stain resistance of the workpiece after irradiation with active energy rays.

[0105] [Active energy ray curable release adhesive composition] Thus, the active energy ray-curable release adhesive composition of the present invention is obtained by mixing an acrylic resin (A), an active energy ray-curable compound (B), and optionally a crosslinking agent (C), a photopolymerization initiator (D), an ethylenically unsaturated compound, and other components.

[0106] The active energy ray-curable release adhesive composition of the present invention is crosslinked with the above-mentioned crosslinking agent (C) and is suitably used as the adhesive layer of a release adhesive sheet. After this release adhesive sheet is bonded to a workpiece, irradiation with active energy rays hardens the adhesive layer, causing a decrease in adhesive strength and thus exhibiting release properties. This property can be utilized to temporarily protect the surface of various workpieces during processing. The following describes release-type adhesive sheets.

[0107] Examples of workpieces protected by the above-mentioned peel-off adhesive sheet include semiconductor wafers, printed circuit boards, glass products, metal plates, and plastic plates.

[0108] The above-mentioned release-type adhesive sheet typically comprises a base sheet, an adhesive layer made of the active energy ray-curable release-type adhesive composition of the present invention, and a release film. As a method for producing such a release-type adhesive sheet, first, the active energy ray-curable release-type adhesive composition of the present invention is applied directly to the release film or base sheet, either as is or with its concentration adjusted using a suitable organic solvent. Then, it is dried, for example, by heat treatment at 80-105°C for 0.5-10 minutes, and this is then attached to the base sheet or release film to obtain the release-type adhesive sheet. Furthermore, aging may be performed after drying to balance the adhesive properties.

[0109] Examples of the above-mentioned base 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; polyfluoroethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyfluoroethylene; 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 cellulose triacetate and cellophane; acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; polystyrene; polycarbonate; polyarylate; polyimide; and sheets made of at least one synthetic resin selected from the group consisting of these; as well as metal foils of aluminum, copper, and iron; paper such as fine paper and glassine paper; and woven or nonwoven fabrics made of glass fibers, natural fibers, synthetic fibers, etc. These base sheets can be used as single layers or as multi-layered structures made by laminating two or more types. Among these, sheets made of synthetic resin are preferred from the viewpoint of weight reduction and other factors.

[0110] Furthermore, as the release film, for example, various synthetic resin sheets, paper, textiles, nonwoven fabrics, etc., as exemplified in the base sheet, can be used, which have been treated with a release agent.

[0111] Furthermore, the coating method for the above-mentioned active energy ray-curable release adhesive composition is not particularly limited as long as it is a general coating method, and examples include roll coating, die coating, gravure coating, comma coating, and screen printing.

[0112] The thickness of the adhesive layer in the above-mentioned peel-type adhesive sheet is usually preferably 1 to 200 μm, and more preferably 10 to 100 μm.

[0113] As active energy rays, various types of light rays can be used, including far-ultraviolet, ultraviolet, near-ultraviolet, and infrared rays, as well as electromagnetic waves such as X-rays and gamma rays, electron beams, proton beams, and neutron beams. However, ultraviolet light is advantageous due to its curing speed, availability of irradiation equipment, and cost.

[0114] The cumulative dose of ultraviolet radiation mentioned above is typically 50-3000 mJ / cm². 2 Preferably 100-1000 mJ / cm² 2 Furthermore, the irradiation time 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, but it is usually only a few seconds, and in some cases even less than one second.

[0115] The adhesive strength of the above-mentioned peel-type adhesive sheet varies depending on the type of base sheet, the type of workpiece, etc., but the 180-degree peel strength before irradiation with active energy rays is usually 1 N / 25 mm or more, and preferably 3 N / 25 mm or more.

[0116] The above-mentioned peel-type adhesive sheet typically exhibits a peel strength after active energy irradiation that is lower than the peel strength before active energy ray irradiation. The 180-degree peel strength of the above-mentioned peelable adhesive sheet after irradiation with active energy rays is usually 1 N / 25 mm or less, and preferably 0.5 N / 25 mm or less.

[0117] A release-type adhesive sheet using the active energy ray-curable release-type adhesive composition of the present invention as the adhesive layer can be bonded to a workpiece, temporarily protecting the surface of the workpiece, and then irradiated with active energy rays. This hardens the adhesive layer and reduces its adhesive strength, allowing it to be easily peeled off the workpiece. [Examples]

[0118] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the invention. Hereinafter, "%" and "parts" refer to weight-based amounts.

[0119] <Preparation of acrylic resin (A) solution>

[0120] [Acrylic resin (A-1)] In a reactor equipped with a temperature controller, thermometer, stirrer, dropping funnel, and reflux condenser, 70 parts of ethyl acetate and 0.04 parts of 2,2'-azobisisobutyronitrile (AIBN (thermal polymerization initiator)) as a polymerization catalyst were charged. The mixture was heated while stirring until reflux was achieved. Once the internal temperature stabilized, a mixture of 91.9 parts of n-butyl acrylate (a1), 0.1 parts of 2-hydroxyethyl methacrylate (a2), and 8.0 parts of acrylic acid was added dropwise over 2 hours and the reaction was carried out under reflux. Subsequently, 13.3 parts of toluene and 0.08 parts of AIBN were added 3 hours after the start of the reaction, and the reaction was terminated 5.5 hours after the start of the reaction to obtain an acrylic resin (A-1) solution with a glass transition temperature of -48.2°C, resin content of 35.0%, viscosity of 7,000 mPa·s (25°C), and weight-average molecular weight Mw 877,000.

[0121] [Acrylic resin (A-2)] In a reactor equipped with a temperature controller, thermometer, stirrer, dropping funnel, and reflux condenser, 75 parts of ethyl acetate were charged, and the temperature was raised while stirring until reflux was achieved. Once the internal temperature stabilized, a mixture of 70.0 parts n-butyl acrylate (a1), 20.0 parts methyl methacrylate, 9.9 parts acrylic acid (a2), 0.1 parts 2-hydroxyethyl methacrylate (a3), 3.75 parts ethyl acetate, and 0.035 parts AIBN was added dropwise over 2 hours and the reaction was carried out under reflux. Next, 22.5 parts of ethyl acetate and 0.04 parts of AIBN were added 3 hours after the start of the reaction, and 7.5 parts of ethyl acetate and 0.04 parts of AIBN were added 5 hours after the start of the reaction, and the reaction was completed 7 hours after the start of the reaction (polymerization rate approximately 99%), yielding an acrylic resin (A-2) solution with a glass transition temperature of -24.2°C, resin content of 38.6%, viscosity of 8,500 mPa·s (25°C), and weight-average molecular weight Mw 456,000.

[0122] [Acrylic resin (A-3)] In a reactor equipped with a temperature controller, thermometer, stirrer, dropping funnel, and reflux condenser, 70 parts of ethyl acetate, 5.1 parts of toluene, and 0.059 parts of 2,2'-azobisisobutyronitrile (AIBN (thermal polymerization initiator)) as a polymerization catalyst were charged. The mixture was heated while stirring until reflux was achieved. Once the internal temperature stabilized, a mixture of n-butyl acrylate (a1), 6.0 parts of acrylic acid (a2), 0.2 parts of 2-hydroxyethyl methacrylate (a3), and 5.0 parts of vinyl acetate was added dropwise over 2 hours and the reaction was carried out under reflux. Next, 9.6 parts of toluene and 0.05 parts of HEMA were added 3 hours after the start of the reaction, and 2.2 parts of toluene and 0.07 parts of AIBN were added 3.5 hours after the start of the reaction. The reaction was terminated 6.5 hours after the start of the reaction (polymerization rate approximately 99%), yielding an acrylic resin (A-3) solution with a glass transition temperature of -46.8°C, a resin content of 35.0%, a viscosity of 3,000 mPa·s (25°C), and a weight-average molecular weight of Mw 540,000.

[0123] [Acrylic resin (A'-1)] In a reactor equipped with a temperature controller, thermometer, stirrer, dropping funnel, and reflux condenser, 41.8 parts of ethyl acetate and 0.023 parts of 2,2'-azobisisobutyronitrile (AIBN (thermal polymerization initiator)) as a polymerization catalyst were charged. The mixture was heated while stirring until reflux was achieved. Once the internal temperature stabilized, a mixture of 64.85 parts of n-butyl acrylate (a1), 0.15 parts of acrylic acid (a2), 5.0 parts of 2-hydroxyethyl methacrylate (a3), and 30.0 parts of methyl methacrylate was added dropwise over 2 hours and the reaction was carried out under reflux. Next, 7.5 parts of ethyl acetate and 0.025 parts of AIBN were added 3 hours after the start of the reaction, and 12.5 parts of ethyl acetate and 0.05 parts of AIBN were added 5 hours after the start of the reaction. The reaction was terminated 7 hours after the start of the reaction (polymerization rate approximately 99%), yielding an acrylic resin (A'-1) solution with a glass transition temperature of -19.1°C, a resin content of 40.0%, a viscosity of 11,500 mPa·s (25°C), and a weight-average molecular weight of Mw507,000.

[0124] [Acrylic resin (A'-2)] In a reactor equipped with a temperature controller, thermometer, stirrer, dropping funnel, and reflux condenser, 67.0 parts of ethyl acetate, 17.0 parts of toluene, and 0.006 parts of 2,2'-azobisisobutyronitrile (AIBN (thermal polymerization initiator)) as a polymerization catalyst were charged. The mixture was heated while stirring until reflux was achieved. Once the internal temperature stabilized, a mixture of 40.0 parts of 2-ethylhexyl acrylate (a1), 10.0 parts of acrylic acid (a2), 50.0 parts of methyl acrylate, 4.0 parts of ethyl acetate, and 0.064 parts of AIBN was added dropwise over 2 hours and the reaction was carried out under reflux. Next, 10.0 parts of toluene and 0.04 parts of AIBN were added 3 hours after the start of the reaction, and another 10.0 parts of toluene and 0.04 parts of AIBN were added 5 hours after the start of the reaction. The reaction was terminated 7 hours after the start of the reaction (polymerization rate approximately 99%), yielding an acrylic resin (A'-2) solution with a glass transition temperature of -23.9°C, resin content of 43.2%, viscosity of 222,000 mPa·s (25°C), and weight-average molecular weight Mw of 650,000.

[0125] Table 1 shows the details of the obtained acrylic resins (A-1) to (A-3) and (A'-1) to (A'-2).

[0126] [Table 1] * 2EHA:2-Ethylhexylacrylate BA: n-butyl acrylate MA: Methyl acrylate MMA: Methyl methacrylate AAc: Acrylic acid HEMA: 2-hydroxyethyl methacrylate VAc: vinyl acetate

[0127] <Preparation of Activated Energy Ray Curable Compound (B)> [Preparation of the active energy ray-curable compound (B-1)] (Urethane (meth)acrylate (b-1)) In a four-necked flask equipped with a temperature controller, thermometer, stirrer, water-cooled condenser, and nitrogen gas inlet, 18.3 parts of isophorone diisocyanate (isocyanate group content: 37.8%) (manufactured by Evonik Japan), 81.7 parts of a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (hydroxyl value: 119.1 mg KOH / g), 0.04 parts of 2,6-di-tert-butylcresol as a polymerization inhibitor, and 0.02 parts of dibutyltin dilaurate, a tin-based compound, as a reaction catalyst were charged. The mixture was reacted at 60°C until the residual isocyanate group content was reduced to 0.3% or less, at which point the reaction was terminated to obtain a mixture of urethane acrylate (b-1) (6 ethylenically unsaturated groups, weight-average molecular weight 1,300, acryloyl group concentration 25.4 mmol / g mmol / g).

[0128] [Preparation of Activated Energy Ray Curable Compound (B-2)] (Urethane (meth)acrylate (b-2)) In a four-necked flask equipped with a thermometer, stirrer, water-cooled condenser, and nitrogen gas inlet, 6.6 g (0.03 mol) of isophorone diisocyanate, 93.4 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (hydroxyl value 48 mg KOH / g), 0.06 g of 2,6-di-tert-butylcresol as a polymerization inhibitor, and 0.02 g of dibutyltin dilaurate as a reaction catalyst were charged. The reaction was carried out at 60°C, and the reaction was stopped when the remaining isocyanate groups were 0.3% or less to obtain urethane acrylate (b-2) (10 ethylenically unsaturated groups, weight-average molecular weight 2,000, acryloyl group concentration 5.0 mmol / g).

[0129] [Preparation of Activated Energy Ray Curable Compound (B-3)] (Urethane (meth)acrylate (b-3)) A four-necked flask equipped with a temperature controller, thermometer, stirrer, water-cooled condenser, and nitrogen gas inlet contains 9.4 parts of isophorone diisocyanate (isocyanate group content: 37.8%) (manufactured by Evonik Japan) and Sannix PP-2000. 43.3 parts (hydroxyl value: 54.9 mg KOH / g) (manufactured by Sanyo Chemical Industries), 47.3 parts of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (hydroxyl value: 51 mg KOH / g), 0.04 parts of 2,6-di-tert-butyl cresol as a polymerization inhibitor, and 0.02 parts of dibutyltin dilaurate, a tin-based compound, as a reaction catalyst were charged and the mixture was carried out at 60°C. The reaction was terminated when the remaining isocyanate groups were 0.3% or less to obtain a mixture of urethane acrylate (b-3) (10 ethylenically unsaturated groups, weight-average molecular weight 7,500, acryloyl group concentration 4.73 mmol / g).

[0130] [Preparation of the active energy ray-curable compound (B'-1)] (Multifunctional (meth)acrylate) A mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (manufactured by Toa Synthetic Chemical Co., Ltd.: Aronics M-405)

[0131] [Preparation of Activated Energy Ray Curable Compound (B'-2)] (Multifunctional (meth)acrylate) Trimethylolpropane triacrylate (manufactured by Toa Synthetic Chemical Co., Ltd.: Aronics M-309)

[0132] <Example 1~ 4, Reference example 1 Comparative Examples 1-3> The acrylic resin (A), active energy ray curable compound (B), and the following components prepared above were blended in the amounts shown in Table 2 to obtain an active energy ray curable release adhesive composition, and a release adhesive sheet was prepared.

[0133] [Crosslinking agent (C)] • Isocyanate-based crosslinking agent (C-1): Trimethylolpropane adduct of tolylene diisocyanate (manufactured by Tosoh Corporation: Coronate L-55E) • Epoxy crosslinking agent (C-2): 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Company: Tetrad C)

[0134] [Photopolymerization initiator (D)] • Photopolymerization initiator (D-1): 1-Hydroxycyclohexylphenyl ketone (IGMresins: OMNIRAD184)

[0135] [Preparation of release-type adhesive sheets] Using the obtained active energy ray-curable release adhesive composition, the components listed in Table 3 were blended and the temperature was adjusted to 100°C. The mixture was then applied to a polyethylene terephthalate film (film thickness 38 μm) (Toray Industries, Ltd., "T60 Lumirror") as a base sheet using an applicator, dried at 100°C for 2 minutes, cooled to room temperature, and then attached to a release film (Mitsui Chemicals Tohcello Co., Ltd., "SP-PET3801-BU"). A release adhesive sheet (adhesive layer thickness 25 μm) was obtained by aging at 40°C for 7 days. The following evaluations were performed using the obtained peel-type adhesive sheets. The results are shown in Table 2.

[0136] (Adhesion before irradiation with active energy rays) A 25mm x 100mm test piece was prepared from the release adhesive sheet obtained above. After removing the release film, it was pressed onto a stainless steel plate (SUS304BA plate) by rolling a 2kg rubber roller back and forth twice in an atmosphere of 23°C and 50% relative humidity. After standing in the same atmosphere for 30 minutes, the 180° peel strength (N / 25mm) was measured at a peeling speed of 300mm / min and evaluated according to the following criteria. ◎:15N / 25mm or more ○: 10N / 25mm or more, less than 15N / 25mm ×: Less than 10N / 25mm

[0137] (Adhesion after irradiation with active energy rays) A 25mm x 100mm test specimen was prepared from the release adhesive sheet obtained above. After removing the release film, it was pressed onto a stainless steel plate (SUS304BA plate) by passing a 2kg rubber roller back and forth twice in an atmosphere of 23°C and 50% relative humidity. After being left in an atmosphere of 23°C and 50% relative humidity for 30 minutes, ultraviolet irradiation (cumulative irradiation dose of 180mJ / cm2) was performed using one 80W high-pressure mercury lamp from a height of 18cm at a conveyor speed of 51.0m / min. After being left to stand for another 30 minutes in an atmosphere of 23°C and 50% relative humidity, the 180-degree peel strength (N / 25mm) was measured at a peeling speed of 300mm / min. ◎: 0.2N / less than 25mm ○: 0.2N / 25mm or more, less than 0.5N / 25mm ×: 0.5N / 25mm or more

[0138] (Stain resistance) In evaluating the adhesive strength after irradiation with the activated energy rays described above, the surface condition of the stainless steel plate after peeling off the release-type adhesive sheet was visually inspected and evaluated as follows. ○: No glue residue ×: Glue residue present

[0139] [Table 2]

[0140] Example 1~ 4 Before irradiation with active energy rays, the material exhibited extremely high adhesion, but after irradiation with active energy rays, its adhesion decreased significantly, resulting in excellent ease of peeling and stain resistance. On the other hand, Comparative Example 1 and 2 Therefore, the adhesion strength before irradiation with active energy rays was poor, which was highly likely to affect chip breakage and misalignment during processing. Furthermore, in Comparative Example 3, which used an acrylic resin in which the ratio (a2) / (a3) of carboxyl group-containing structural units (a2) to hydroxyl group-containing structural units (a3) ​​was 0.03, Comparative Examples 1-2 andSimilarly, the adhesion was inferior to that before irradiation with active energy rays. Furthermore, in Comparative Example 4, which did not contain hydroxyl group-containing structural units (a3) ​​in the acrylic resin, the substrate showed such high adhesive strength that it fractured before active energy ray curing. However, after active energy ray irradiation, the reduction in adhesive strength was insufficient, adhesive residue was left over the entire surface, and the stain resistance was also poor.

[0141] Based on the above results, an active energy ray curable release adhesive composition containing an acrylic resin (A) and an active energy ray curable compound (B) is provided. The acrylic resin (A) contains structural units derived from a carboxyl group-containing monomer (a2) and structural units derived from a hydroxyl group-containing monomer (a3), and the weight percentage ratio (a2) / (a3) of structural units derived from the carboxyl group-containing monomer (a2) to the hydroxyl group-containing monomer (a3) ​​is 10 to 150. The active energy ray curable compound (B) contains urethane (meth)acrylate (b). Furthermore, the content of the active energy ray curable compound (B) is 75 to 120 parts by weight per 100 parts by weight of the acrylic resin. This demonstrates that an adhesive composition can be obtained that exhibits excellent adhesive strength before and after irradiation with active energy rays, as well as excellent stain resistance after peeling, even as a release-type adhesive sheet. [Industrial applicability]

[0142] The active energy ray curable release adhesive composition of the present invention can be suitably used as an adhesive film for temporary surface protection when processing semiconductor wafers, printed circuit boards, glass products, metal plates, plastic plates, etc.

Claims

1. An active energy ray-curable release adhesive composition containing an acrylic resin (A) and an active energy ray-curable compound (B), The acrylic resin (A) contains structural units derived from a (meth)acrylic monomer (a1), structural units derived from a carboxyl group-containing monomer (a2), and structural units derived from a hydroxyl group-containing monomer (a3), wherein the structural units derived from the (meth)acrylic monomer (a1) include structural units derived from n-butyl acrylate. With respect to the entire structural unit constituting the acrylic resin (A), The content of structural units derived from the carboxyl group-containing monomer (a2) is 1 to 40% by weight, and the content of structural units derived from the hydroxyl group-containing monomer (a3) ​​is 0.01 to 2% by weight. The weight percentage ratio (a2) / (a3) of structural units derived from the carboxyl group-containing monomer (a2) to structural units derived from the hydroxyl group-containing monomer (a3) ​​is 30 to 150. An active energy ray-curable release adhesive composition characterized in that the active energy ray-curable compound (B) contains urethane (meth)acrylate (b), and the amount of the active energy ray-curable compound (B) is 75 to 120 parts by weight per 100 parts by weight of the acrylic resin (A).

2. The active energy ray curable release adhesive composition according to claim 1, characterized in that the acrylic resin (A) contains 5 to 40% by weight of structural units derived from the carboxyl group-containing monomer (a2).

3. The active energy ray curable release adhesive composition according to claim 1 or 2, characterized in that the ratio of weight percent of structural units derived from the carboxyl group-containing monomer (a2) to structural units derived from the hydroxyl group-containing monomer (a3) ​​of the above acrylic resin (A) is 30 to 120.

4. The active energy ray curable release adhesive composition according to any one of claims 1 to 3, further characterized by containing a crosslinking agent (C).

5. The active energy ray curable release adhesive composition according to any one of claims 1 to 4, further characterized by containing a photopolymerization initiator (D).

6. A peelable adhesive sheet characterized by having an adhesive layer in which the active energy ray-curable peelable adhesive composition according to any one of claims 1 to 5 is crosslinked.

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