JP7434754B2 - Active energy ray-curable peelable adhesive composition and peelable adhesive sheet - Google Patents

Description

The present invention relates to active energy used in the adhesive layer of a peelable adhesive sheet for temporary surface protection when processing workpieces such as semiconductor wafers, printed circuit boards, glass products, metal plates, and plastic plates. The present invention relates to a line-curable peelable pressure-sensitive adhesive composition and a peelable pressure-sensitive adhesive sheet.

Conventionally, in processing processes such as manufacturing integrated circuits and drilling holes using semiconductor wafers, adhesive sheets have been used to temporarily protect the surface of the workpiece in order to prevent dirt and damage to the workpiece. is used. In recent years, due to the miniaturization of processing technology and the thinning of films on workpieces, appropriate adhesive strength is required for workpieces. It is necessary to peel off the adhesive, and when removing it, it is required to be able to remove it with light force without leaving any adhesive residue. Furthermore, in recent years, adhesive sheets for surface protection have been used not only for semiconductor wafers but also for processing various members.

As an adhesive film or sheet for temporary surface protection, for example, Patent Document 1 describes an adhesive comprising an adhesive and a radiation-polymerizable compound which is a urethane acrylate oligomer having a weight average molecular weight of 3,000 to 10,000 on a base material surface. A pressure-sensitive adhesive sheet formed by applying a layer is disclosed. It is described that when the above-mentioned pressure-sensitive adhesive sheet is irradiated with ultraviolet rays when it is peeled off, the adhesive force with the adherend decreases rapidly.

Furthermore, Patent Document 2 discloses an acrylic adhesive having a weight average molecular weight of 200,000 or more and a glass transition temperature of -60 to -30°C, a hydroxyl group-containing acrylic compound having three or more acryloyl groups in the molecule, and a diisocyanate. A removable adhesive is disclosed that uses a urethane acrylate compound, which is a reaction product with a removable adhesive, so that less adhesive remains upon re-peeling.

Further, Patent Documents 3 and 4 also disclose pressure-sensitive adhesive sheets that are intended to be peeled off by irradiation with active energy rays.

Japanese Unexamined Patent Publication No. 153376/1986 Japanese Patent Application Publication No. 11-293201 Japanese Patent Application Publication No. 2012-039053 Japanese Patent Application Publication No. 11-335655

However, although the technology disclosed in Patent Document 1 describes that the adhesive strength before irradiation with active energy rays is good, with the miniaturization of processing technology in recent years, the adhesive strength before irradiation with active energy rays is lower than before. It is required that the adhesive strength be high and the adhesive strength before active energy ray irradiation be low, and it is considered difficult to obtain a sufficiently satisfactory adhesive strength with the technique disclosed in Patent Document 1.

The technology disclosed in Patent Document 2 described above improves adhesive residue during peeling, but with the recent miniaturization of processing technology, it is possible that the peelability after irradiation with active energy rays may not be sufficient. This is a concern and further improvements are required.

Furthermore, the technique disclosed in Patent Document 3 describes improvement in the pick-up properties of semiconductor chips, but because the acryloyl group concentration of the urethane (meth)acrylate compound is low, the adhesive force after irradiation with ultraviolet rays does not decrease. It is insufficient. In addition, the technology disclosed in Patent Document 4 describes improvement in water washability of the adhesive remaining on the adherend, but this is because the peelability after irradiation is insufficient in the first place. Since adhesive remains, improvement is required in terms of removability after irradiation.

Therefore, in the present invention, against this background, we have developed an adhesive that has good adhesive strength before irradiation with active energy rays and has excellent removability (slight tackiness, stain resistance) after irradiation with active energy rays. The object of the present invention is to provide an active energy ray-curable peelable adhesive composition that can be obtained.

However, as a result of intensive studies in view of the above circumstances, the present inventors have developed an active energy ray-curable peelable adhesive containing an acrylic resin, a urethane (meth)acrylate compound, a crosslinking agent, and a photopolymerization initiator. In the composition, an acrylic resin containing an oxyalkylene structure is used, and a urethane (meth)acrylate compound with a high concentration of (meth)acryloyl groups is used, and the acrylic resin and the urethane (meth)acrylate compound are combined. We have discovered that by containing it in a specific proportion, the adhesive strength before irradiation with active energy rays is good, and the adhesive strength decreases after irradiation with active energy rays, resulting in extremely excellent releasability. Completed the invention.

That is, the present invention provides an active energy ray-curable peelable adhesive containing an acrylic resin (A), a urethane (meth)acrylate compound (B), a crosslinking agent (C), and a photopolymerization initiator (D). A composition,
The acrylic resin (A) is copolymerized with a copolymerization component (a) containing an oxyalkylene structure-containing monomer (a1) and further containing at least one of a hydroxyl group-containing monomer (a2) and a carboxyl group-containing monomer (a3). It is an acrylic resin,
The (meth)acryloyl group concentration of the urethane (meth)acrylate compound (B) is 0.5 mmol/g or more,
An active energy ray-curable peelable adhesive composition characterized in that the content of the urethane (meth)acrylate compound (B) is 10 to 200 parts by weight based on 100 parts by weight of the acrylic resin (A). Make things the first gist.
The second aspect of the present invention is a releasable pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer crosslinked with the active energy ray-curable peelable pressure-sensitive adhesive composition of the first aspect.

The active energy ray-curable peelable adhesive composition of the present invention contains an acrylic resin (A), a urethane (meth)acrylate compound (B), a crosslinking agent (C), and a photopolymerization initiator (D). An active energy ray-curable peelable adhesive composition, wherein the acrylic resin (A) contains an oxyalkylene structure-containing monomer (a1), and further contains a hydroxyl group-containing monomer (a2) and a carboxyl group-containing monomer (a3). ) is an acrylic resin copolymerized with a copolymerization component (a) containing at least one of the above, and the (meth)acryloyl group concentration of the urethane (meth)acrylate compound (B) is 0.5 mmol/g or more. The content of the urethane (meth)acrylate compound (B) is 10 to 200 parts by weight based on 100 parts by weight of the acrylic resin (A). Therefore, when this active energy ray-curable release type adhesive composition is used as an adhesive layer of a release type adhesive sheet, the adhesive strength before active energy ray irradiation is good, and the adhesive strength after active energy ray irradiation is good. It can be made to have excellent removability (slight adhesion, stain resistance).

Hereinafter, embodiments for carrying out the present invention will be specifically described, but the present invention is not limited thereto.
In the present invention, "(meth)acrylic" means acrylic or methacrylic, "(meth)acryloyl" means acryloyl or methacryloyl, and "(meth)acrylate" means acrylate or methacrylate.
Furthermore, the acrylic resin is a resin obtained by polymerizing a polymerization component containing at least one (meth)acrylate monomer.
In the present invention, the term "sheet" is not particularly distinguished from "film" or "tape", but is meant to include these as well.

The active energy ray-curable releasable adhesive composition of the present invention is generally used as an adhesive for releasable adhesive sheets that are intended to be peeled off after being bonded to workpieces such as metal plates, plastic plates, semiconductor wafers, etc. used for the agent layer. The above-mentioned releasable adhesive sheet is formed by coating an active energy ray-curable releasable adhesive composition on a base sheet to form an adhesive layer, and after laminating it to a workpiece, By irradiating the adhesive layer with active energy rays, the adhesive layer is cured, its adhesive strength is reduced, and it can be easily peeled off from the workpiece.

Hereinafter, the acrylic resin (A), the urethane (meth)acrylate compound (B), the crosslinking agent (C), and the photopolymerization initiator ( D) will be explained.

[Acrylic resin (A)]
The acrylic resin (A) used in the present invention is a copolymer component (a) containing an oxyalkylene structure-containing monomer (a1) and further containing at least one of a hydroxyl group-containing monomer (a2) and a carboxyl group-containing monomer (a3). It is an acrylic resin obtained by copolymerizing.

（式中、Ｘは炭素数１～１０、好ましくは１～３のアルキレン基、Ｙはアルキル基、アリール基またはアラルキル基、Ｒ₁は水素原子またはメチル基、ｎは１以上の整数である。）

The oxyalkylene structure-containing monomer (a1) is preferably an oxyalkylene structure-containing (meth)acrylate monomer. Further, the above-mentioned oxyalkylene structure-containing (meth)acrylate monomer is represented by the following general formula (1).

(In the formula, X is an alkylene group having 1 to 10 carbon atoms, preferably 1 to 3 carbon atoms, Y is an alkyl group, aryl group, or aralkyl group, R ₁ is a hydrogen atom or a methyl group, and n is an integer of 1 or more. .)

Specific examples of the oxyalkylene structure-containing (meth)acrylate monomer represented by the above general formula (1) include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and 3-methoxybutyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-butoxydiethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxydipropylene glycol Aliphatic compounds such as (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, octoxypolyethylene glycol-polypropylene glycol-mono(meth)acrylate, lauroxypolyethylene glycol mono(meth)acrylate, stearoxypolyethylene glycol mono(meth)acrylate, etc. Oxyalkylene chain-containing (meth)acrylate, 2-phenoxyethyl (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol-polypropylene glycol-(meth)acrylate, nonylphenol ethylene oxide adduct (meth)acrylate, etc. Examples include aromatic oxyalkylene chain-containing (meth)acrylates. Among these, aliphatic oxyalkylene chain-containing (meth)acrylates are preferred from the viewpoint of releasability after irradiation with active energy rays, particularly aliphatic oxyethylene chain-containing (meth)acrylates, and especially 2-methoxyethyl (meth)acrylates are preferred. ) acrylate, methoxydiethylene glycol (meth)acrylate, and methoxytriethylene glycol (meth)acrylate are preferred.

The content of the oxyalkylene structure-containing monomer (a1) in the copolymerization component (a) of the acrylic resin (A) is preferably 10 to 99% by weight, more preferably 30 to 97% by weight, particularly Preferably it is 55 to 95% by weight. If this content is too small, the adhesive strength before irradiation with active energy rays tends to be too high, and when it is too large, the adhesive strength before irradiated with active energy rays tends to be too low.

The hydroxyl group-containing monomer (a2) is preferably a hydroxyl group-containing (meth)acrylate monomer, and specifically, for example, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxybutyl (meth)acrylate, etc. (meth)acrylic acid hydroxyalkyl esters such as hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; caprolactone-modified monomers such as caprolactone-modified 2-hydroxyethyl (meth)acrylate; , diethylene glycol (meth)acrylate, oxyalkylene modified monomers such as polyethylene glycol (meth)acrylate, primary hydroxyl group-containing monomers such as 2-acryloyloxyethyl-2-hydroxyethylphthalic acid; 2-hydroxypropyl (meth)acrylate, Secondary hydroxyl group-containing monomers such as 2-hydroxybutyl (meth)acrylate and 3-chloro-2-hydroxypropyl (meth)acrylate; Tertiary hydroxyl group-containing monomers such as 2,2-dimethyl 2-hydroxyethyl (meth)acrylate, etc. can be mentioned. These may be used alone or in combination of two or more.
Among the above-mentioned hydroxyl group-containing monomers, primary hydroxyl group-containing monomers are preferred, and more preferably 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, particularly preferably 2-hydroxyethyl (meth)acrylate.

In addition, examples of the carboxy group-containing monomer (a3) include (meth)acrylic acid, (meth)acrylic acid dimer, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, Examples include acrylamide N-glycolic acid and cinnamic acid. These may be used alone or in combination of two or more. Among these, (meth)acrylic acid is preferred because it has excellent reactivity with the crosslinking agent (C) described below and excellent adhesive strength before irradiation with active energy rays.

The content ratio of at least one of the hydroxyl group-containing monomer (a2) and the carboxyl group-containing monomer (a3) in the copolymerization component (a) of the acrylic resin (A) is preferably 0.1 to 50% by weight. , more preferably 1 to 20% by weight, particularly preferably 3 to 10% by weight. If this content is too small, the adhesive strength before irradiation with active energy rays tends to be too low, and when it is too large, the adhesive strength before irradiated with active energy rays tends to be too high.

Further, the content of the hydroxyl group-containing monomer (a2) in the copolymerization component (a) of the acrylic resin (A) is usually 50% by weight or less, preferably 30% by weight or less, particularly preferably 1 ~10% by weight. If this content is too large, coatability tends to decrease. Note that if this content is too small, the adhesive strength before irradiation with active energy rays tends to be too low.

Furthermore, the content of the carboxy group-containing monomer (a3) in the copolymerization component (a) of the acrylic resin (A) is usually 40% by weight or less, preferably 20% by weight or less, particularly preferably It is 1 to 10% by weight. If this content is too large, coatability tends to decrease. Note that if this content is too small, the adhesive strength before irradiation with active energy rays tends to be too low.

In the present invention, from the viewpoint of adhesive strength before irradiation with active energy rays, a hydroxyl group-containing monomer (a2) and a carboxyl group-containing monomer (a3) are used in combination as the copolymerization component (a) of the acrylic resin (A). It is preferable.

When the above-mentioned hydroxyl group-containing monomer (a2) and carboxyl group-containing monomer (a3) are used together, the weight ratio (hydroxyl group-containing monomer (a2)/carboxy group-containing monomer (a3)) is usually 1/99 to 99/1, The ratio is preferably 50/50 to 99/1, particularly preferably 80/20 to 99/1. If the ratio of the hydroxyl group-containing monomer (a2) is too high, the adhesive strength before irradiation with active energy rays tends to decrease, and if the ratio of the carboxy group-containing monomer (a3) is too high, the adhesive strength after irradiation with active energy rays tends to decrease. tends to be higher.

The copolymerization component (a) of the acrylic resin (A) preferably contains a (meth)acrylic acid alkyl ester monomer (a4) in addition to the above monomers, and further contains other copolymerization components as necessary. may also contain a sexual monomer (a5).

The (meth)acrylic acid alkyl ester monomer (a4) has an alkyl group having usually 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and particularly preferably 4 to 8 carbon atoms. can be mentioned. If the number of carbon atoms is too large, releasability tends to decrease, and the workpiece tends to be more likely to be contaminated.

Specifically, the (meth)acrylic acid alkyl ester monomer (a4) is, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert- Butyl (meth)acrylate, n-propyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl acrylate, isodecyl (meth)acrylate, lauryl ( Aliphatic (meth)acrylic acid alkyl esters such as meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, and isostearyl (meth)acrylate; alicyclics such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate Examples include (meth)acrylic acid esters of the above group. These may be used alone or in combination of two or more.
Among the above (meth)acrylic acid alkyl ester monomers (a4), methyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred in terms of copolymerizability, adhesive properties, ease of handling, and ease of obtaining raw materials. is preferred.

The content of the (meth)acrylic acid alkyl ester monomer (a4) in the copolymerization component (a) of the acrylic resin (A) is usually 50% by weight or less, preferably 35% by weight or less. If this content is too large, the adhesive strength before irradiation with active energy rays tends to become too high.

Examples of the other copolymerizable monomers (a5) include:
Acetoacetyl group-containing monomers such as 2-(acetoacetoxy)ethyl (meth)acrylate and allyl acetoacetate;
Glycidyl group-containing monomers such as glycidyl (meth)acrylate and allylglycidyl (meth)acrylate;
Carboxylic acid vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl stearate, vinyl benzoate;
Aromatic rings such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenyldiethylene glycol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, styrene, α-methylstyrene, etc. Containing monomer;
Biphenyloxy structure-containing (meth)acrylic acid ester monomers such as biphenyloxyethyl (meth)acrylate;
Ethoxymethyl (meth)acrylamide, n-butoxymethyl (meth)acrylamide, (meth)acryloylmorpholine, dimethyl (meth)acrylamide, diethyl (meth)acrylamide, dimethylaminopropylacrylamide, (meth)acrylamide N-methylol (meth)acrylamide (meth)acrylamide monomers such as;
Acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, itaconic acid dialkyl ester, fumaric acid dialkyl ester, allyl alcohol, acryl chloride, methyl vinyl ketone, allyl trimethyl ammonium chloride, dimethyl Examples include allyl vinyl ketone. These other copolymerizable monomers (a5) may be used alone or in combination of two or more.

The content of the other copolymerizable monomer (a5) in the copolymerizable component (a) of the acrylic resin (A) is usually 20% by weight or less, preferably 15% by weight or less, more preferably 10% by weight or less. It is. If the other copolymerizable monomer (a5) is too large, the adhesive properties tend to deteriorate.

The acrylic resin (A) used in the present invention is at least one of an oxyalkylene structure-containing monomer (a1), a hydroxyl group-containing monomer (a2), and a carboxyl group-containing monomer (a3), preferably a (meth)acrylic acid alkyl ester monomer. (a4) can be obtained by copolymerizing copolymerization component (a) containing other copolymerizable monomers (a5) as needed.
However, from the viewpoint of stability during polymerization of the acrylic resin (A), it is preferable to select each monomer so that the side chain does not contain a radically polymerizable group.

The polymerization method for obtaining the above-mentioned acrylic resin (A) can be carried out appropriately by conventionally known methods such as solution radical polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization. Among these, solution radical polymerization is preferred because it allows the acrylic resin (A) to be produced safely and stably with any monomer composition.

In the solution radical polymerization, for example, at least one of the oxyalkylene structure-containing monomer (a1), the hydroxyl group-containing monomer (a2), and the carboxyl group-containing monomer (a3), preferably a (meth)acrylic acid alkyl ester-based Monomer (a4), copolymerizable components (a) such as other copolymerizable monomers (a5) if necessary, and a polymerization initiator are mixed or added dropwise, and heated under reflux or at 50 to 98°C for 1 to 20 ℃. It is enough to polymerize for about a period of time.

Examples of the organic solvent used in the above 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 ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

Examples of the above polymerization initiators include azo polymerization initiators such as azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), which are common radical polymerization initiators, benzoyl peroxide, lauroyl Specific examples include peroxide-based polymerization initiators such as peroxide, di-tert-butyl peroxide, and cumene hydroperoxide.

In this way, the acrylic resin (A) used in the present invention can be obtained.

The glass transition temperature (Tg) of the acrylic resin (A) is preferably a relatively low temperature, preferably -30°C or lower, more preferably -30°C or lower, in order to further reduce the adhesive strength after irradiation with active energy rays. is -65 to -30°C, more preferably -50 to -35°C. If the glass transition temperature is too high, the adhesive strength after irradiation with active energy rays tends not to be sufficiently reduced, and if it is too low, the contamination of the workpiece tends to be high.

The above glass transition temperature (Tg) is a value calculated by applying the glass transition temperature and weight fraction when each monomer constituting the acrylic resin (A) is a homopolymer to the Fox formula below. It is.
Here, the glass transition temperature when the monomer constituting the acrylic resin (A) is a homopolymer is usually measured by a differential scanning calorimeter (DSC), and is determined by JIS K 7121-1987 or JIS It can be measured by a method based on K 6240.

The weight average molecular weight of the acrylic resin (A) is usually 10,000 to 2,500,000, preferably 100,000 to 2,000,000, particularly preferably 150,000 to 1,500,000, particularly preferably 200,000 to 1,000,000. If the weight average molecular weight is too small, the stain resistance to the workpiece tends to be low, and if it is too large, the coatability tends to decrease, and it also tends to be disadvantageous in terms of cost.

Further, the degree of dispersion (weight average molecular weight/number average molecular weight) of the acrylic resin (A) is preferably 20 or less, particularly preferably 10 or less, further preferably 7 or less, particularly 5 or less. preferable. If the degree of dispersion is too high, contamination of the workpiece tends to increase. Note that the lower limit of the degree of dispersion is usually 1.1 from the viewpoint of manufacturing limitations.

The above weight average molecular weight is the weight average molecular weight in terms of standard polystyrene molecular weight. GPC KF-806L (exclusion limit molecular weight: 2×10 ⁷ , separation range: 100 to 2×10 ⁷ , theoretical plate number: 10,000 plates/piece, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm ) in series, and the number average molecular weight can also be obtained by the same method.

[Urethane (meth)acrylate compound (B)]
The urethane (meth)acrylate compound (B) used in the present invention is a compound having a carbamate group and a (meth)acryloyl group.

The urethane (meth)acrylate compound (B) is a urethane (meth)acrylate compound (B1) that is a reaction product of a hydroxyl group-containing (meth)acrylate compound (b1) and a polyvalent isocyanate compound (b2). It may be a urethane (meth)acrylate compound (B2) which is a reaction product of a hydroxyl group-containing (meth)acrylate compound (b1), a polyvalent isocyanate compound (b2) and a polyol compound (b3). It's okay. In particular, in the present invention, in terms of releasability after irradiation with active energy rays, the urethane (meth)acrylate compound (B) is a hydroxyl group-containing (meth)acrylate compound (b1) and a polyvalent isocyanate compound. A reaction product with (b2) [urethane (meth)acrylate compound (B1)] is preferable.
In addition, in the present invention, only one type of urethane (meth)acrylate compound (B) may be used, or two or more types may be used in combination.

The hydroxyl group-containing (meth)acrylate compound (b1) preferably has one hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. ) acrylate, hydroxyalkyl (meth)acrylates such as 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-A hydroxyl group-containing (meth)acrylate compound containing one ethylenically unsaturated group such as (meth)acryloyloxypropyl (meth)acrylate;
Hydroxyl group-containing (meth)acrylate compounds containing two ethylenically unsaturated groups such as glycerin di(meth)acrylate and 2-hydroxy-3-acryloyl-oxypropyl methacrylate;
Pentaerythritol tri(meth)acrylate, caprolactone modified pentaerythritol tri(meth)acrylate, ethylene oxide modified pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone modified dipentaerythritol penta(meth)acrylate, ethylene Examples include hydroxyl group-containing (meth)acrylate compounds containing three or more ethylenically unsaturated groups, such as oxide-modified dipentaerythritol penta(meth)acrylate.
These hydroxyl group-containing (meth)acrylate compounds (b1) can be used alone or in combination of two or more.

Among the above hydroxyl group-containing (meth)acrylate compounds (b1), the hydroxyl group-containing (meth)acrylate compounds (b1) containing three or more ethylenically unsaturated groups are particularly good in terms of their reactivity and versatility. Preferably, pentaerythritol tri(meth)acrylate and dipentaerythritol penta(meth)acrylate are particularly preferred, and dipentaerythritol penta(meth)acrylate is particularly preferred.

Examples of the polyvalent isocyanate compound (b2) include aromatic compounds such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate. polyvalent isocyanate;
Aliphatic polyisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, lysine triisocyanate;
Alicyclic polyvalent isocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate;
Or isocyanurates or multimer compounds of these polyvalent isocyanates, allophanate-type polyisocyanates, bullet-type polyisocyanates, water-dispersed polyisocyanates (for example, "Aquanate 100", "Aquanate 110" manufactured by Nippon Polyurethane Industries, Ltd.), "Aquanate 200", "Aquanate 210", etc.).

Among these, aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and norbornene have excellent reactivity and versatility. Alicyclic diisocyanates such as diisocyanates are preferred, particularly preferred are isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, and hexamethylene diisocyanate, and even more preferred is isophorone diisocyanate.

The polyol compound (b3) may be any compound containing two or more hydroxyl groups, such as aliphatic polyols, alicyclic polyols, polyether polyols, polyester polyols, polycarbonate polyols, and polyolefins. Examples include polyols based on polyols, polybutadiene polyols, polyisoprene polyols, (meth)acrylic polyols, and polysiloxane polyols. These can be used alone or in combination of two or more.

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

Examples of the alicyclic polyols include cyclohexanediols such as 1,4-cyclohexanediol and cyclohexyl dimethanol, hydrogenated bisphenols such as hydrogenated bisphenol A, and tricyclodecane dimethanol.

Examples of the polyether polyols include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, polypentamethylene glycol, and polyhexamethylene glycol, and random or block combinations of these polyalkylene glycols. Examples include polymers.

The polyester polyols include, for example, a condensation polymer of a polyhydric alcohol and a polycarboxylic acid; a ring-opening polymer of a cyclic ester (lactone); and three types of components: a polyhydric alcohol, a polycarboxylic acid, and a cyclic ester. and the like.

Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylene diol, 1,3-tetramethylene diol, 2-methyl-1,3-tetramethylene diol, Methylene diol, 1,5-pentamethylene diol, neopentyl glycol, 1,6-hexamethylene diol, 3-methyl-1,5-pentamethylene diol, 2,4-diethyl-1,5-pentamethylene diol, glycerin , trimethylolpropane, trimethylolethane, cyclohexanediols (1,4-cyclohexanediol, etc.), bisphenols (bisphenol A, etc.), sugar alcohols (xylitol, sorbitol, etc.), and the like.
Examples of the polyhydric carboxylic acids include aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid; -Alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid;
Examples include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalene dicarboxylic acid, paraphenylene dicarboxylic acid, and trimellitic acid.
Examples of the cyclic ester include propiolactone, β-methyl-δ-valerolactone, and ε-caprolactone.

Examples of the polycarbonate polyol include a reaction product of a polyhydric alcohol and phosgene; a ring-opening polymer of a cyclic carbonate (alkylene carbonate, etc.), and the like.
Examples of the polyhydric alcohol include the polyhydric alcohols exemplified in the description of the polyester polyol, and examples of the alkylene carbonate include ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, hexamethylene carbonate, etc. It will be done.
Note that the polycarbonate polyol may be a compound having a carbonate bond in the molecule and having a hydroxyl group at the end, and may have an ester bond in addition to the carbonate bond.

Examples of the above-mentioned polyolefin polyols include those having a homopolymer or copolymer of ethylene, propylene, butene, etc. as a saturated hydrocarbon skeleton, and having a hydroxyl group at the end of the molecule.

Examples of the above-mentioned polybutadiene-based polyols include those having a copolymer of butadiene as a hydrocarbon skeleton and a hydroxyl group at the end of the molecule.
The polybutadiene polyol may be a hydrogenated polybutadiene polyol in which all or part of the ethylenically unsaturated groups contained in its structure are hydrogenated.

Examples of the above-mentioned polyisoprene-based polyols include those having an isoprene copolymer as a hydrocarbon skeleton and a hydroxyl group at the end of the molecule.
The polyisoprene polyol may be a hydrogenated polyisoprene polyol in which all or a portion of the ethylenically unsaturated groups contained in its structure are hydrogenated.

Examples of the (meth)acrylic polyol include polymers or copolymers of (meth)acrylic esters having at least two hydroxyl groups in the molecule; For example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, (meth)acrylate Examples include alkyl (meth)acrylates such as 2-ethylhexyl acid, decyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate.

Examples of the polysiloxane polyol include dimethylpolysiloxane polyol and methylphenylpolysiloxane polyol.

Among these, aliphatic polyols and alicyclic polyols are preferably used in terms of cost, and polyester polyols, polyether polyols, and polycarbonate polyols are preferably used in terms of versatility.

The weight average molecular weight of the polyol compound (b3) is preferably 60 to 3,000, particularly preferably 100 to 1,000, and even more preferably 150 to 800. If the weight average molecular weight of the polyol compound (b3) is too large, the resulting urethane (meth)acrylate compound (B) and acrylic resin (A) will be difficult to mix uniformly, resulting in adhesive residue on the workpiece. It tends to be easier. Furthermore, if the weight average molecular weight of the polyol compound (b3) is too small, cracks tend to occur in the adhesive layer after irradiation with active energy rays.

The urethane (meth)acrylate compound (B) can be produced by reacting the above components using a known reaction method.
Usually, when obtaining the urethane (meth)acrylate compound (B1), the hydroxyl group-containing (meth)acrylate compound (b1) and the polyvalent isocyanate compound (b2) are combined to form the urethane (meth)acrylate compound (B2). ), the polyol compound (b3) can be further produced by charging the polyol compound (b3) into a reactor all at once or separately and carrying out a urethanization reaction using a known reaction method. In addition, when producing the urethane (meth)acrylate compound (B2), the reaction product obtained by reacting the polyol compound (b3) and the polyvalent isocyanate compound (b2) in advance has a hydroxyl group-containing ( The method of reacting the meth)acrylate compound (b1) is useful in terms of stability of the urethanization reaction, reduction of by-products, and the like.

In the reaction between the hydroxyl group-containing (meth)acrylate compound (b1) and the polyvalent isocyanate compound (b2), it is preferable to use a reaction catalyst for the purpose of promoting the reaction, such as dibutyl Organometallic compounds such as tin dilaurate, trimethyltin hydroxide, and tetra-n-butyltin; metal salts such as zinc octenoate, tin octenoate, tin octylate, cobalt naphthenate, stannous chloride, and tin chloride; Triethylamine, benzyldiethylamine, 1,4-diazabicyclo[2,2,2]octane, 1,8-diazabicyclo[5,4,0]undecene, N,N,N',N'-tetramethyl-1,3- In addition to amine catalysts such as butanediamine and N-ethylmorpholine, bismuth nitrate, bismuth bromide, bismuth iodide, and bismuth sulfide, organic bismuth compounds such as dibutyl bismuth dilaurate and dioctyl bismuth dilaurate, and bismuth 2-ethylhexanoate. salt, bismuth naphthenate, bismuth isodecanoate, bismuth neodecanoate, bismuth laurate, bismuth maleate, bismuth stearate, bismuth oleate, bismuth linoleate, bismuth acetate, bismuth libis neodeca Bismuth-based catalysts such as organic acid bismuth salts such as noate, bismuth disalicylate, and bismuth disalicylate; zirconium-based catalysts such as inorganic zirconium, organic zirconium, and simple zirconium; zinc 2-ethylhexanoate/zirconium tetraacetylacetate; Among them, organic bismuth compounds are preferred, and bismuth 2-ethylhexanoate is particularly preferred. Note that these catalysts can be used alone or in combination of two or more.

In the above urethanization reaction, organic solvents that do not have functional groups that react with isocyanate groups, such as esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, and aromatic solvents such as toluene and xylene, are used. Organic solvents such as those of the above-mentioned family can be used.

Further, the reaction temperature of the above urethanization 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.

The urethane-forming reaction described above is terminated when the content of residual isocyanate groups in the reaction system becomes 0.5% by weight or less, thereby obtaining the urethane (meth)acrylate compound (B).

The (meth)acryloyl group concentration of the urethane (meth)acrylate compound (B) thus obtained is 0.5 mmol/g or more. It is preferably 1 to 20 mmol/g, more preferably 2 to 10 mmol/g, particularly preferably 3 to 8 mmol/g. By setting the (meth)acryloyl group concentration of the urethane (meth)acrylate compound (B) within the above range, excellent releasability after irradiation with active energy rays can be achieved.

In addition, the urethane (meth)acrylate compound (B) preferably has 6 or more ethylenically unsaturated groups, more preferably 6 to 18, particularly The number is preferably 8 to 15.
If the number of such ethylenically unsaturated groups is too large, the crosslinking density after irradiation with active energy rays becomes too large, making it easy for cracks to occur in the adhesive layer, and if the number is too small, sufficient crosslinking density cannot be obtained, so It tends to become difficult to peel off after radiation irradiation.

The weight average molecular weight of the urethane (meth)acrylate compound (B) is usually 500 to 10,000, preferably 750 to 5,000, more preferably 1,000 to 4,000. If the weight average molecular weight is too large, the viscosity of the urethane (meth)acrylate compound (B) will increase, the compatibility with the acrylic resin (A) will decrease, and adhesive will tend to remain on the workpiece. There is. If the weight average molecular weight is too small, the urethane (meth)acrylate compound (B) tends to bleed from the pressure-sensitive adhesive sheet, resulting in adhesive residue.

The above weight average molecular weight is the weight average molecular weight in terms of standard polystyrene molecular weight, and a high performance liquid chromatograph (manufactured by Waters, "ACQUITY APC System") was equipped with a column: ACQUITY APC XT 450 x 1, ACQUITY APC XT It is measured by using four ACQUITY APC XT 45 x 2 in series, 1 x 200.

The viscosity of the urethane (meth)acrylate compound (B) used in the present invention at 60° C. is preferably from 500 to 100,000 mPa·s, particularly preferably from 1,000 to 50,000 mPa·s. When the viscosity is outside the above range, coating properties tend to decrease. Note that the viscosity can be measured using an E-type viscometer.

In the present invention, the content of the urethane (meth)acrylate compound (B) is 10 to 200 parts by weight based on 100 parts by weight of the acrylic resin (A). The amount is preferably 15 to 100 parts by weight, particularly preferably 20 to 80 parts by weight. If the content of the urethane (meth)acrylate compound (B) is too low, the releasability after irradiation with active energy rays tends to decrease, and if it is too high, cracks may occur in the adhesive layer after irradiation with active energy rays. It tends to be easier.

[Crosslinking agent (C)]
Examples of the crosslinking agent (C) used in the present invention include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, oxazoline crosslinking agents, melamine crosslinking agents, aldehyde crosslinking agents, and amine crosslinking agents. Can be mentioned. Among these, it is preferable to use an isocyanate-based crosslinking agent from the viewpoint of improving the adhesiveness with the base sheet of the peelable pressure-sensitive adhesive sheet and the reactivity with the acrylic resin (A).
Further, these crosslinking agents (C) may be used alone or in combination of two or more.

Examples of the isocyanate-based crosslinking agent include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hexamethylene diisocyanate, diphenylmethane-4,4-diisocyanate, and isophorone. Diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate, and adducts of these polyisocyanate compounds with polyol compounds such as trimethylolpropane. Examples of the polyisocyanate compounds include burette bodies and isocyanurate bodies of these polyisocyanate compounds.
Among these, in terms of drug resistance and reactivity with functional groups, isocyanurates of hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,6-tolylene diisocyanate and trimethylol are preferred. Adducts with propane, isocyanurates of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, and adducts of tetramethylxylylene diisocyanate with trimethylolpropane are preferred.

Examples of the epoxy crosslinking 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. , trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether, 1,3'-bis(N,N-diglycidylaminomethyl)cyclohexane, N , N,N',N'-tetraglycidyl-m-xylene diamine and the like.

Examples of the aziridine-based crosslinking agent include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4 '-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), and the like.

Examples of the oxazoline crosslinking agent include 2,2'-bis(2-oxazoline),
1,2-bis(2-oxazolin-2-yl)ethane, 1,4-bis(2-oxazolin-2-yl)butane, 1,8-bis(2-oxazolin-2-yl)butane, 1, Aliphatic or Aromatic-containing bisoxazoline compounds, 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2 Examples include polymers of one or more addition-polymerizable oxazolines such as -isopropenyl-4-methyl-2-oxazoline and 2-isopropenyl-5-ethyl-2-oxazoline.

Examples of the melamine-based crosslinking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexaptoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, melamine resin, and the like. .

Examples of the aldehyde crosslinking agent include glyoxal, malondialdehyde, succindialdehyde, maleic dialdehyde, glutardialdehyde, formaldehyde, acetaldehyde, benzaldehyde, and the like.

Examples of the amine crosslinking agent include hexamethylene diamine, triethyl diamine, polyethylene imine, hexamethylene tetraamine, diethylene triamine, triethyl tetraamine, isophorone diamine, amino resin, polyamide, and the like.

The content of the crosslinking agent (C) is usually the sum of the acrylic resin (A) and the urethane (meth)acrylate compound (B) (in the case of using the ethylenically unsaturated compound described below, the amount of the ethylenically unsaturated The amount is 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 parts by weight, per 100 parts by weight (including compounds). Too little cross-linking agent (C) tends to reduce the cohesive force of the adhesive and cause adhesive residue, while too much cross-linking agent (C) reduces flexibility and adhesive strength, making it difficult for the workpiece to be processed. There is a tendency for floating to occur between the parts.

[Photopolymerizable initiator (D)]
The photopolymerization initiator (D) used in the present invention may be one that generates radicals by the action of light, for example,
Diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl Phenylketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-methyl-2-morpholino(4-thiomethylphenyl)propane- Acetophenones such as 1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone oligomers Class;
Benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether;
Benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, 3,3',4,4'-tetra(ter
t-Butylperoxycarbonyl)benzophenone, 2,4,6-trimethylbenzophenone, 4-benzoyl-N,N-dimethyl-N-[2-(1-oxo-2-propenyloxy)ethyl]benzenemethanaminium bromide , (4-benzoylbenzyl)trimethylammonium chloride and other benzophenones;
2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2-(3-dimethylamino-2-hydroxy)-3,4- Thioxanthone such as dimethyl-9H-thioxanthone-9-one mesochloride;
2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenyl Acyl phosphophone oxides such as phosphine oxide;
etc. Among them, acetophenones are preferred, and 1-hydroxycyclohexylphenyl ketone is particularly preferred. In addition, these photopolymerization initiators (D) can be used individually or in combination of 2 or more types.

In addition, as an auxiliary agent for these photopolymerization initiators (D), for example, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler ketone)
, 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, 4-
Ethyl dimethylaminobenzoate, (n-butoxy)ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4- It is also possible to use diisopropylthioxanthone or the like in combination. These auxiliaries can also be used alone or in combination of two or more.

The content of the photopolymerization initiator (D) is the sum of the acrylic resin (A) and the urethane (meth)acrylate compound (B) (in the case of using the ethylenically unsaturated compound described below, the amount of the ethylenically unsaturated The amount is preferably 0.1 to 20 parts by weight, particularly preferably 0.5 to 15 parts by weight, particularly preferably 1 to 10 parts by weight, based on 100 parts by weight (including compounds). If the content of the photopolymerization initiator (D) is too small, the peelability after irradiation with active energy rays tends to decrease, and if it is too large, the contamination of the workpiece after irradiation with active energy rays tends to increase. There is.

[Ethylenically unsaturated compound]
It is also preferable that the active energy ray-curable release adhesive composition of the present invention contains an ethylenically unsaturated compound from the viewpoint of release characteristics after irradiation with active energy rays. The above-mentioned ethylenically unsaturated compound can be used without particular limitation as long as it has an ethylenically unsaturated group, and among them, (meth)acrylate is preferred in terms of compatibility with the acrylic resin (A). A type compound is preferable. In addition, the said ethylenically unsaturated compound excludes the said urethane (meth)acrylate type compound (B).

The ethylenically unsaturated compound has excellent peeling properties after irradiation with active energy rays, and the number of ethylenically unsaturated groups per molecule is usually 2 to 10, preferably 3 to 9, particularly preferably There are 4 to 8 pieces. If the number of such ethylenically unsaturated groups is too large, the crosslinking density after irradiation with active energy rays becomes too large, and cracks tend to occur in the adhesive layer, whereas if the number is too small, sufficient crosslinking density cannot be obtained. , tends to be difficult to peel off after irradiation with active energy rays.

Examples of the ethylenically unsaturated compounds 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 di(meth)acrylate, propylene oxide modified bisphenol A di(meth)acrylate, cyclohexane di(meth)acrylate Methanol di(meth)acrylate, ethoxylated cyclohexanedimethanol di(meth)acrylate, dimethyloldicyclopentanedi(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate Acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, phthalic acid diglycidyl ester di(meth)acrylate, hydroxy Compounds having two ethylenically unsaturated groups, such as pivalic acid-modified neopentyl glycol di(meth)acrylate and isocyanuric acid-ethylene oxide-modified diacrylate;
Trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tri(meth)acryloyloxyethoxytrimethylolpropane, isocyanuric acid ethylene oxide modified triacrylate, caprolactone modified pentaerythritol tri(meth)acrylate, ethylene oxide modified penta Compounds having three ethylenically unsaturated groups such as erythritol tri(meth)acrylate and ethoxylated glycerin triacrylate;
Pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, glycerin polyglycidyl ether poly(meth)acrylate, caprolactone modified dipentaerythritol penta(meth)acrylate, caprolactone modified di Pentaerythritol hexa(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 tetra(meth)acrylate ) Compounds having 4 or more ethylenically unsaturated groups such as acrylate;
etc.

In addition, as the ethylenically unsaturated compound, a Michael adduct of (meth)acrylic acid or a 2-(meth)acryloyloxyethyl dicarboxylic acid monoester can also be used in combination, and the Michael adduct of (meth)acrylic acid is , (meth)acrylic acid dimer, (meth)acrylic acid trimer, (meth)acrylic acid tetramer, and the like.
The above-mentioned 2-(meth)acryloyloxyethyldicarboxylic acid monoester is a carboxylic acid having a specific substituent, such as 2-(meth)acryloyloxyethylsuccinic acid monoester, 2-(meth)acryloyloxyethyl phthalic acid Examples include monoester, 2-(meth)acryloyloxyethylhexahydrophthalic acid monoester, and the like. Furthermore, other oligoester acrylates may also be mentioned.

Among these, ethylenically unsaturated compounds having no hydroxyl group are preferred because they have excellent adhesive properties after irradiation with active energy rays, and more preferred are pentaerythritol tetra(meth)acrylate and dipentaerythritol hexa(meth)acrylate. acrylate, caprolactone-modified pentaerythritol tetra(meth)acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, and ethylene oxide-modified pentaerythritol tetra(meth)acrylate, particularly preferably pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, Pentaerythritol hexa(meth)acrylate. The above ethylenically unsaturated compounds may be used alone or in combination of two or more.

In addition, in the present invention, the skeleton of the compound obtained by removing (meth)acrylic acid from the ethylenically unsaturated compound and the hydroxyl group-containing (meth)acrylate compound used in the production of the urethane (meth)acrylate compound (B) It is preferable that the skeletons of the compounds obtained by removing (meth)acrylic acid from (b1) are the same as each other in terms of excellent compatibility and adhesive properties.

The content of the ethylenically unsaturated compound is usually 5 to 100 parts by weight, preferably 10 to 80 parts by weight, particularly preferably 20 to 60 parts by weight, based on 100 parts by weight of the acrylic resin (A). be. If the content of the ethylenically unsaturated compound is too small, it will tend to be difficult to peel off after irradiation with active energy rays, and if it is too large, the stain resistance of the workpiece after peeling will tend to decrease.

[Other ingredients]
The active energy ray-curable peelable adhesive composition of the present invention may contain, for example, a small amount of a monofunctional monomer, an antistatic agent, an antioxidant, a plasticizer, a filler, a pigment, within a range that does not impair the effects of the present invention. It may further contain additives such as diluents, anti-aging agents, ultraviolet absorbers, and ultraviolet stabilizers, and these additives can be used alone or in combination of two or more. In particular, antioxidants are effective in maintaining the stability of the adhesive layer. The content of the antioxidant when blended is not particularly limited, but is preferably 0.01 to 5% by weight based on the active energy ray-curable peelable adhesive composition.
In addition to the above-mentioned additives, the active energy ray-curable peelable adhesive composition of the present invention contains impurities, etc. contained in the manufacturing raw materials of the constituent components of the active energy ray-curable peelable adhesive composition. may be contained in a small amount.

In addition, the active energy ray-curable peelable adhesive composition of the present invention has low contamination resistance on workpieces after irradiation with active energy rays, and therefore it is preferable to use terpene resins, rosin resins, chroman resins, phenol resins, etc. It is preferable that no tackifier resin such as resin, styrene resin, petroleum resin, etc. is included.

Thus, the acrylic resin (A), the urethane (meth)acrylate compound (B), the crosslinking agent (C), the photopolymerization initiator (D), if necessary, the ethylenically unsaturated compound, other components, etc. By mixing optional components, the active energy ray-curable peelable adhesive composition of the present invention can be obtained.

The active energy ray-curable peelable adhesive composition of the present invention is crosslinked with the above-mentioned crosslinking agent (C), and is suitably used as an adhesive layer of a peelable adhesive sheet. After this peelable adhesive sheet is bonded to the workpiece, it is irradiated with active energy rays to form a urethane (meth)acrylate compound (B) [and, if it contains an ethylenically unsaturated compound, Ethylenically unsaturated compound] polymerizes and the adhesive layer hardens, resulting in a decrease in adhesive strength and exhibits removability. Utilizing this property, it is used to temporarily protect the surface of various workpieces when processing them.
The releasable pressure-sensitive adhesive sheet will be explained below.

Examples of the workpieces protected by the peelable adhesive sheet include semiconductor wafers, printed circuit boards, glass products, metal plates, plastic plates, and the like.

The above-mentioned peelable pressure-sensitive adhesive sheet usually has a base sheet, a pressure-sensitive adhesive layer made of the active energy ray-curable peelable pressure-sensitive adhesive composition of the present invention, and a release film. As a method for producing such a removable adhesive sheet, first, the active energy ray-curable releasable adhesive composition of the present invention is applied directly onto a release film or a base sheet, either as is or after adjusting the concentration with an appropriate organic solvent. Coat. Thereafter, a releasable adhesive sheet can be obtained by drying, for example, by heat treatment at 80 to 105° C. for 0.5 to 10 minutes, and attaching this to a base sheet or a release film. Furthermore, in order to balance the adhesive properties, further aging may be performed after drying.

Examples of the 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; polyvinyl fluoride; , polyvinylidene fluoride, polyfluorinated ethylene resins such as polyethylene fluoride; polyamides such as nylon 6, nylon 6,6; polyvinyl chloride, polyvinyl chloride/vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene- Vinyl polymers such as vinyl alcohol copolymers, polyvinyl alcohol, and vinylon; Cellulose resins such as cellulose triacetate and cellophane; Acrylics such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate Resin; Sheet made of at least one synthetic resin selected from the group consisting of polystyrene; polycarbonate; polyarylate; polyimide, etc.; metal foil of aluminum, copper, iron, paper such as high-quality paper and glassine paper, glass fiber, natural fiber , woven fabrics and non-woven fabrics made of synthetic fibers and the like. These base sheets can be used as a single layer or as a multilayer in which two or more types are laminated. Among these, sheets made of synthetic resin are preferred from the viewpoint of weight reduction.

Furthermore, as the above-mentioned release film, for example, various synthetic resin sheets, paper, woven fabrics, non-woven fabrics, etc. exemplified in the above-mentioned base sheet, which have been subjected to release treatment, can be used.

Furthermore, the method for applying the active energy ray-curable peelable adhesive composition is not particularly limited as long as it is a general coating method, and examples include roll coating, die coating, gravure coating, and comma coating. , screen printing, and the like.

The thickness of the adhesive layer in the above-mentioned peelable adhesive sheet is usually preferably 1 to 200 μm, more preferably 10 to 100 μm.

As active energy rays, in addition to far ultraviolet rays, ultraviolet rays, near ultraviolet rays, infrared rays, electromagnetic waves such as X-rays and gamma rays, electron beams, proton rays, and neutron rays can be used. It is advantageous to use ultraviolet rays due to the ease of obtaining equipment, cost, etc.

The cumulative irradiation amount of the ultraviolet rays is usually 50 to 3000 mJ/cm ² , preferably 100 to 1000 mJ/cm ² . In addition, 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 several seconds, and in some cases even a very short time of less than one second. good.

The adhesive strength of the above-mentioned peelable 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 0.3 N/25 mm or more, and is preferably is 1N/25mm or more.

The above-mentioned peelable pressure-sensitive adhesive sheet usually has a peel strength after irradiation with active energy that is lower than the peel strength before irradiation with active energy rays.
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, preferably 0.5 N/25 mm or less.
Further, the 30 degree peel strength of the peelable adhesive sheet after irradiation with active energy rays is 10 N/25 mm or less, preferably 3 N/25 mm or less.

In addition, between 180 degree peel strength and 30 degree peel strength, 30 degree peel strength generally has a larger value (requires greater force) and can more effectively evaluate the superiority or inferiority of adhesive strength. It is.

Further, the rate of change in 180 degree peel strength before and after irradiation with active energy rays (rate of decrease in peel strength) determined by the following formula is preferably 70% or more, more preferably 80% or more.
Rate of change in adhesive strength (%) = [(adhesive strength before active energy ray irradiation - adhesive strength after active energy ray irradiation)/adhesive strength before active energy ray irradiation] x 100

A releasable adhesive sheet using the active energy ray-curable releasable adhesive composition of the present invention as an adhesive layer is bonded to a workpiece, and after temporarily protecting the surface of the workpiece, By irradiating the active energy rays, the adhesive layer is cured and its adhesive strength is reduced, so that it can be easily peeled off from the workpiece.

EXAMPLES 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 unless it exceeds the gist thereof. In addition, hereinafter, "%" and "part" mean a weight basis.

<Preparation of acrylic resin (A) solution>
[Acrylic resin (A-1)]
In a reactor equipped with a temperature controller, a thermometer, a stirrer, a dropping funnel, and a reflux condenser, 95 parts of ethyl acetate, 7.5 parts of methyl ethyl ketone, and 0.025 parts of azobisisobutyronitrile (AIBN) as a polymerization catalyst were placed. of methoxyethyl acrylate (a1), 0.1 part of 2-hydroxyethyl methacrylate (a2), and acrylic acid as copolymerization components. A mixture of 8 parts of (a2), 31.9 parts of methyl acrylate (a3), 0.038 parts of AIBN, and 5.0 parts of ethyl acetate was added dropwise over 2 hours to react under reflux. Next, 3 hours after the start of the reaction, a solution containing 3.8 parts of ethyl acetate and 0.038 parts of AIBN was added, and 5 hours after the start of the reaction, 28.8 parts of ethyl acetate and 2,2'-azobis(2, A solution containing 0.025 parts of 4-dimethylvaleronitrile (ADVN) was added, and 7 hours after the start of the reaction, 17.5 parts of ethyl acetate was added to terminate the reaction, resulting in acrylic resin (A-1). A solution glass transition temperature of -15.3°C, resin content of 37.4%, and viscosity of 30,000 mPa·s (25°C) was obtained.

[Acrylic resins (A-2) to (A-6) and (A'-1)]
With the monomer composition shown in Table 1, polymerization was carried out according to the method for preparing the acrylic resin (A-1) above to obtain an acrylic resin solution. However, the final dilution concentration was adjusted according to the viscosity of the acrylic resin.

Urethane (meth)acrylic compound (B) was prepared as follows.

<Preparation of urethane (meth)acrylate compound (B)>
[Urethane acrylate (B-1)]
In a four-neck flask equipped with a temperature controller, thermometer, stirrer, water-cooled condenser, and nitrogen gas inlet, 6.6 parts of isophorone diisocyanate, a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (hydroxyl value 48 mg KOH /g) 93.4 parts, 0.06 part of 2,6-di-tert-butylcresol as a polymerization inhibitor, and 0.06 parts of bismuth 2-ethylhexanoate bismuth salt (manufactured by Nitto Kasei Co., Ltd.) as a reaction catalyst. 3 parts of urethane acrylate (B-1) (10 ethylenically unsaturated groups, weight average molecular weight 2,000 , acryloyl group concentration 5.0 mmol/g) mixture was obtained.

[Urethane acrylate (B'-1)]
In a four-necked flask equipped with a temperature controller, thermometer, stirrer, water-cooled condenser, and nitrogen gas inlet, 30.05 parts of isophorone diisocyanate, 53.98 parts of polyalkylene carbonate diol, and 15.93 parts of 2-hydroxyethyl acrylate were added. 0.040 part of 4-methoxyphenol as a polymerization inhibitor and 0.001 part of dibutyltin dilaurate as a reaction catalyst were reacted at 55°C to 80°C, and when the residual isocyanate group became 0.3% or less. The reaction was terminated, and a mixture of urethane acrylate (B'-1) (2 ethylenically unsaturated groups, weight average molecular weight 5000, acryloyl group concentration 0.4 mmol/g) was obtained.

In addition, each compounded component shown below was prepared.

[Crosslinking agent (C)]
・Isocyanate crosslinking agent (C-1): Trimethylolpropane adduct of tolylene diisocyanate (manufactured by Tosoh Corporation: Coronate L55E)

[Photopolymerizable initiator (D)]
・Photopolymerization initiator (D-1): 1-hydroxycyclohexylphenyl ketone (manufactured by IGM Resins: OMNIRAD184)

<Examples 1 to 6, Comparative Examples 1 to 3>
[Preparation of adhesive composition]
The components prepared above were blended in the amounts shown in Table 2, and toluene was mixed as a diluting solvent to obtain an active energy ray-curable peelable adhesive composition solution (solid content 20%). .

[Preparation of peelable adhesive sheet]
The obtained active energy ray-curable peelable adhesive composition solution was applied as a base sheet onto an easily adhesive polyethylene terephthalate film (thickness: 38 μm) (manufactured by Toray Industries, Inc., "T60 Lumirror") using an applicator. After that, it was dried at 100°C for 2 minutes, attached to a release film (manufactured by Mitsui Chemicals Tohcello Co., Ltd., "SP-PET 38 01-BU"), and aged at 40°C for 7 days to form a release adhesive sheet ( A pressure-sensitive adhesive layer having a thickness of 25 μm was obtained.
The following evaluation was performed using the obtained peelable pressure-sensitive adhesive sheet.

[180 degree peel strength before active energy ray irradiation]
A 25 mm x 100 mm test piece was prepared from the peelable adhesive sheet obtained above, and after peeling off the release film, it was placed on a stainless steel plate (SUS304BA plate) at 23°C and in an atmosphere of 50% relative humidity, weighing 2 kg. The rubber roller was moved back and forth twice to adhere the film under pressure, and the film was allowed to stand in the same atmosphere for 30 minutes, after which the 180 degree peel strength (N/25 mm) was measured at a peel rate of 300 mm/min.

[180 degree peel strength after irradiation with active energy rays]
A 25 mm x 100 mm test piece was prepared from the peelable adhesive sheet obtained above, and after peeling off the release film, it was placed on a stainless steel plate (SUS304BA plate) at 23°C and in an atmosphere of 50% relative humidity, weighing 2 kg. Pressure was applied by moving a rubber roller back and forth twice, and after leaving it for 30 minutes in an atmosphere of 23°C and 50% relative humidity, using one 80W high-pressure mercury lamp, from a height of 18cm at 5.1m/min. Ultraviolet irradiation (total irradiation amount: 180 mJ/cm ² ) was carried out at a conveyor speed of . After further standing for 30 minutes in an atmosphere of 23° C. and 50% relative humidity, the 180 degree peel strength (N/25 mm) was measured at a peel rate of 300 mm/min.

[30 degree peel strength after irradiation with active energy rays]
A 25 mm x 100 mm test piece was prepared from the peelable adhesive sheet obtained above, and after peeling off the release film, it was placed on a stainless steel plate (SUS304BA plate) at 23°C and in an atmosphere of 50% relative humidity, weighing 2 kg. After applying pressure by moving a rubber roller back and forth twice and leaving it to stand for 30 minutes in an atmosphere of 23°C and 50% relative humidity, it was affixed at a height of 5.1m from a height of 18cm using one 80W high-pressure mercury lamp. Ultraviolet irradiation (total irradiation amount: 180 mJ/cm ² ) was carried out at a conveyor speed of min. After further standing for 30 minutes in an atmosphere of 23° C. and 50% relative humidity, 30 degree peel strength (N/25 mm) was measured at a peel rate of 300 mm/min, and evaluation was performed according to the following evaluation criteria.
[Evaluation criteria]
〇...Less than 3N/25mm △...3N/25mm or more, less than 10N/25mm ×...10N/25mm or more

[Adherent contamination]
After peeling off the peelable adhesive sheet from the stainless steel plate (SUS304BA plate) using the above method, adhesive residue on the surface of the stainless steel plate (SUS304BA plate) was visually confirmed, and evaluation was performed according to the following evaluation criteria.
(Evaluation criteria)
○...No glue residue ×...Glue residue

[Haze]
After peeling off the release film from the peelable adhesive sheet obtained above, the diffused transmittance and total light transmittance were measured using HAZE MATER NDH2000 (manufactured by Nippon Denshoku Kogyo Co., Ltd.). Note that this machine complies with JISK7361-1.
The values of the obtained diffused transmittance and total light transmittance were substituted into the following formula to calculate the haze, and the haze was evaluated based on the following criteria.
Haze (%) = (diffuse transmittance/total light transmittance) x 100

The evaluation results of Examples and Comparative Examples are shown in Table 2 below.

From Table 1 above, in the examples, the adhesive strength before irradiation with active energy rays is excellent, and the adhesive strength after irradiation with active energy rays is excellent, whereas the acrylic resin (A) has an oxyalkylene structure. Comparative Example 1, which did not contain monomer (a1), had poor adhesive strength after irradiation with active energy rays. Furthermore, Comparative Example 2, which had a small content of the urethane (meth)acrylate compound (B), had poor adhesive strength after irradiation with active energy rays. Furthermore, Comparative Example 3 in which the urethane (meth)acrylate compound (B) had a low acryloyl group concentration also had poor adhesive strength after irradiation with active energy rays.
From this, it is clear that the acrylic resin (A) contains the oxyalkylene structure-containing monomer (a1), that the content of the urethane (meth)acrylate compound (B) is within a predetermined range, and that the acrylic resin (A) contains the oxyalkylene structure-containing monomer (a1); ) It can be seen that it is important that the acryloyl group concentration of the acrylate compound (B) is within a predetermined range.

The active energy ray-curable peelable adhesive composition of the present invention can be suitably used as a temporary surface protection adhesive film when processing semiconductor wafers, printed circuit boards, glass products, metal plates, plastic plates, etc. Can be done.

Claims (6)

An active energy ray-curable peelable adhesive composition containing an acrylic resin (A), a urethane (meth)acrylate compound (B), a crosslinking agent (C), and a photopolymerization initiator (D),
The acrylic resin (A) contains an oxyalkylene structure-containing monomer (a1), and further contains a copolymerization component (a) containing at least one of a hydroxyl group-containing monomer (a2) and a carboxyl group-containing monomer (a3). It is an acrylic resin that has been
The oxyalkylene structure-containing monomer (a1) does not contain a hydroxyl group or a carboxyl group,
The content ratio of the oxyalkylene structure-containing monomer (a1) in the copolymerization component (a) is 45.9 to 99% by weight,
The (meth)acryloyl group concentration of the urethane (meth)acrylate compound (B) is 0.5 mmol/g or more,
An active energy ray-curable peelable adhesive composition characterized in that the content of the urethane (meth)acrylate compound (B) is 10 to 200 parts by weight based on 100 parts by weight of the acrylic resin (A). thing. The content of the oxyalkylene structure-containing monomer (a1) in the copolymerization component (a) of the acrylic resin (A) is 45.9 to 99% by weight, and the hydroxyl group-containing monomer (a2) and the carboxyl group-containing monomer ( The active energy ray-curable peelable adhesive composition according to claim 1, wherein the content of at least one of a3) is 0.1 to 50% by weight. The active energy ray-curable peelable adhesive composition according to claim 1 or 2, wherein the acrylic resin (A) has a glass transition temperature of -30°C or lower. Claims 1 to 3, wherein the urethane (meth)acrylate compound (B) is a reaction product of a hydroxyl group-containing (meth)acrylate compound (b1) and a polyvalent isocyanate compound (b2). The active energy ray-curable peelable adhesive composition according to any one of the items. The active energy ray-curable peelable adhesive according to any one of claims 1 to 4, wherein the urethane (meth)acrylate compound (B) has 6 or more (meth)acryloyl groups. Composition. A releasable pressure-sensitive adhesive sheet comprising an adhesive layer in which the active energy ray-curable releasable pressure-sensitive adhesive composition according to any one of claims 1 to 5 is crosslinked.