KR20210027424A - Adhesive composition and adhesive sheet - Google Patents

Abstract

It is set as a pressure-sensitive adhesive composition containing a resin represented by formula (1-1) and a photoinitiator. R ¹ to R ⁴ are -H or -CH ₃ . R ⁵ is an alkyl group having 1 to 16 carbon atoms. R ⁶ is an alicyclic hydrocarbon group or an aromatic hydrocarbon group. R ⁷ is -H or -(CH ₂ ) _j -COOH (wherein j is 1 or 2). R ⁸ is a specific group.

Description

Adhesive composition and adhesive sheet

The present invention relates to an adhesive composition and an adhesive sheet.

This application claims priority based on patent application No. 2018-164843 for which it applied to Japan on September 3, 2018, and uses the content here.

Conventionally, various pressure-sensitive adhesive sheets have been used in semiconductor manufacturing processes and the like. Specifically, there are a protective sheet for protecting a wafer in a back-side grinding (backgrinding) process of a semiconductor wafer, and a fixing sheet used in a cutting and dividing (dicing) process from a semiconductor wafer into element pieces. These pressure-sensitive adhesive sheets are re-peelable pressure-sensitive adhesive sheets that are affixed to a semiconductor wafer as an adherend and peeled from the adherend after a predetermined processing step is completed.

As the pressure-sensitive adhesive composition used for the pressure-sensitive adhesive layer of the re-peelable pressure-sensitive adhesive sheet, it is known to contain a resin that has an ethylenic unsaturated group in the molecule and cures with UV (ultraviolet rays).

In Patent Document 1, a (meth)acrylic polymer having two or more hydroxyl groups in the side chain and a compound having an isocyanato group are reacted in the presence of a first catalyst to form a (meth)acrylic polymer having a urethane bond. , And, comprising a step of forming a pressure-sensitive adhesive layer by reacting a (meth)acrylic polymer having the urethane bond and a compound having two or more isocyanato groups in one molecule in the presence of a second catalyst, A method for producing a pressure-sensitive adhesive sheet in which the catalyst is a complex of at least one metal selected from zirconium, titanium, and aluminum, and the second catalyst is an amine catalyst is disclosed.

Japanese Patent No. 5996985

The re-peelable pressure-sensitive adhesive sheet must have sufficient adhesive strength to the adherend when performing a predetermined processing step, be easily peelable from the adherend after the predetermined processing step is completed (ease of peeling), and blood after peeling. It is required that the adhesive layer of the adhesive sheet is not transferred to the complex (no adhesive remains).

However, the conventional pressure-sensitive adhesive sheet did not satisfy all of the above conditions. In particular, when a pressure-sensitive adhesive sheet is affixed to an adherend, processing of the adherend is performed at a high temperature of about 200°C, and then peeled off by UV irradiation, there has been a problem that the residual pressure-sensitive adhesive is liable to occur.

The present invention has been made in view of the above circumstances, and by using it as a material for forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, it has sufficient adhesion to the adherend, and the adherend to which the pressure-sensitive adhesive sheet is attached is brought to a high temperature state, and then returned to room temperature. , Even after peeling after UV irradiation, it is a subject to provide a pressure-sensitive adhesive composition in which a pressure-sensitive adhesive sheet is obtained, while excellent ease of peeling is obtained and the pressure-sensitive adhesive residual is less likely to occur.

In addition, the present invention makes it a subject to provide an adhesive sheet having an adhesive layer containing the adhesive composition.

In order to solve the said subject, the present inventor repeated intensive examination. As a result, resin (A) obtained by addition reaction of a carboxyl group-containing resin (b) obtained by polymerizing a carboxyl group-containing ethylenically unsaturated monomer (a) as an essential monomer component, and an alicyclic epoxy group-containing ethylenically unsaturated compound (c), and , It was found that the pressure-sensitive adhesive composition containing a photopolymerization initiator (B) as an essential component may be used.

The pressure-sensitive adhesive composition containing the resin (A) and the photoinitiator (B) has good heat resistance because the resin (A) has a structure derived from an alicyclic compound. Further, in the pressure-sensitive adhesive composition, the unsaturated bonds in the resin (A) form a three-dimensional crosslinked structure by irradiation with ultraviolet rays (UV) and are cured, thereby changing the adhesive strength. Specifically, sufficient adhesion to the adherend is obtained before UV irradiation on the pressure-sensitive adhesive composition, and after UV irradiation, the adhesion is lowered, resulting in excellent peelability, and sufficient pressure-sensitive adhesive residual to the adherend after peeling. Can be prevented.

The present inventor conceived of the present invention based on such knowledge. That is, the present invention relates to the following matters.

[1] A pressure-sensitive adhesive composition comprising a resin (A) represented by the following general formula (1-1) and a photoinitiator (B).

(In formula (1-1), k, l, m, and n represent the molar composition ratio when k+l+m+n=100. k is more than 0 and not more than 92. l is 0 to 92 50. m is greater than 0 and not more than 90. The sum of k, l and m is 65 to 95. n is 5 to 35. R ¹ to R ⁴ are -H or -CH _3. R ⁵ is a number of carbon atoms It is an alkyl group of 1 to 16. R ⁶ is an alicyclic hydrocarbon group having 3 to 30 carbon atoms or an aromatic hydrocarbon group having 6 to 20 carbon atoms. R ⁷ is -H or -(CH ₂ ) _j -COOH (wherein j is 1 Or 2. R ⁸ is the general formula (1-2) or (1-3). In formulas (1-2) and (1-3), p and q are from 0, 1, 2 Which is selected, s is 0 when p is 0, 1 when p is 1 or 2. R ⁹ is -H or -CH ₃ .)

[2] The pressure-sensitive adhesive composition according to [1], wherein the resin (A) has a weight average molecular weight of 200,000 to 1,000,000.

[3] The pressure-sensitive adhesive composition according to [1] or [2], wherein n in the formula (1-1) is 10 to 33.

[4] The pressure-sensitive adhesive composition according to any one of [1] to [3], wherein k in the formula (1-1) is 45 to 90, l is 4 to 40, and m is 1 to 15. .

[5] The pressure-sensitive adhesive composition according to any one of [1] to [4], further comprising a crosslinking agent (C).

[6] The pressure-sensitive adhesive composition according to any one of [1] to [5], wherein the glass transition temperature of the resin (A) is -80 to 0°C.

[7] A pressure-sensitive adhesive sheet comprising a sheet-like substrate and a pressure-sensitive adhesive layer formed on the substrate, and the pressure-sensitive adhesive layer contains the pressure-sensitive adhesive composition according to any one of [1] to [6].

By using the pressure-sensitive adhesive composition of the present invention as a material for forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, it has sufficient adhesion to the adherend, and the adherend to which the pressure-sensitive adhesive sheet is attached is brought to a high temperature state, then returned to room temperature, and peeled off after UV irradiation. In addition, excellent peelability is obtained, and a pressure-sensitive adhesive sheet in which residual pressure-sensitive adhesive is less likely to occur is obtained.

Hereinafter, the pressure-sensitive adhesive composition and the pressure-sensitive adhesive sheet of the present invention will be described in detail. In addition, this invention is not limited only to the embodiment described below.

"Adhesive composition"

The pressure-sensitive adhesive composition of this embodiment contains a resin (A) and a photoinitiator (B).

(Resin (A))

The resin (A) contained in the pressure-sensitive adhesive composition of the present embodiment is a compound represented by the following general formula (1-1).

(In formula (1-1), k, l, m, and n represent the molar composition ratio when k+l+m+n=100. k is more than 0 and not more than 92. l is 0 to 92 50. m is greater than 0 and not more than 90. The sum of k, l and m is 65 to 95. n is 5 to 35. R ¹ to R ⁴ are -H or -CH _3. R ⁵ is a number of carbon atoms It is an alkyl group of 1 to 16. R ⁶ is an alicyclic hydrocarbon group having 3 to 30 carbon atoms or an aromatic hydrocarbon group having 6 to 20 carbon atoms. R ⁷ is -H or -(CH ₂ ) _j -COOH (wherein j is 1 Or 2. R ⁸ is the general formula (1-2) or (1-3). In formulas (1-2) and (1-3), p and q are from 0, 1, 2 Which is selected, s is 0 when p is 0, 1 when p is 1 or 2. R ⁹ is -H or -CH ₃ .)

In formula (1-1), k, l, m, and n represent the molar composition ratio when k+l+m+n=100. k is greater than 0 and less than or equal to 92. l is from 0 to 50. m is greater than 0 and less than or equal to 90. The sum of k, l and m is 65 to 95. When the total of k, l, and m is 65 or more, it will be a pressure-sensitive adhesive composition in which sufficient adhesion to an adherend is obtained before UV irradiation. It is preferable that it is 70-94, and, as for the total of k, 1, and m, it is more preferable that it is 80-90.

In Formula (1-1), the repeating unit (hereinafter referred to as "repeating unit k") represented in () bound by k is an essential repeating unit. The repeating unit k contributes to the adhesive force of the pressure-sensitive adhesive composition before UV irradiation. The repeating number k of the repeating unit k is more than 0 to 92 or less, preferably 45 to 90, and more preferably 60 to 88.

In formula (1-1), the repeating unit (hereinafter referred to as "repeating unit l") expressed in () bound by l may not be present. In other words, the number of repetitions of the repeating unit l may be zero.

The repeating unit l contributes to the heat resistance of the pressure-sensitive adhesive composition. The repeating number l of the repeating unit l is 0 to 50, preferably 4 to 40, and more preferably 5 to 30.

In Formula (1-1), the repeating unit (hereinafter referred to as "repeating unit m") represented in () bound by m is an essential repeating unit. The repeating unit m contributes to the adhesive force and heat resistance of the pressure-sensitive adhesive composition before UV irradiation. In addition, when the pressure-sensitive adhesive composition contains a crosslinking agent having a functional group reacting with a carboxyl group, the repeating unit m reacts with the crosslinking agent to improve the cohesive strength of the pressure-sensitive adhesive composition. The repeating number m of the repeating unit m is more than 0 to 90 or less, preferably 1 to 15, and more preferably 1 to 5.

In formula (1-1), the repeating unit (hereinafter referred to as "repeating unit n") represented in () bound by n is an essential repeating unit. The repeating unit n contributes to the heat resistance of the pressure-sensitive adhesive composition. The number of repetitions n of the repeating unit n is 5 to 35, preferably 10 to 33, and more preferably 10 to 20. When the repeating unit n is 35 or less, the unsaturated bond in the resin (A) forms a three-dimensional crosslinked structure by UV irradiation and is cured, resulting in a pressure-sensitive adhesive composition in which the adhesive strength is lowered to an appropriate range. In addition, when n is 5 or more, an effect of improving heat resistance due to a structure derived from an alicyclic compound is obtained.

Due to the synergistic effect of the function contributed by each of these repeating units, the pressure-sensitive adhesive composition containing the resin (A) has a better balance of the adhesive force before ultraviolet (UV) irradiation and the adhesive force after UV irradiation. As a result, a sufficient adhesive force is obtained with respect to the adherend before UV irradiation, and after UV irradiation, the adhesive force decreases, resulting in a pressure-sensitive adhesive composition in which more excellent peelability is obtained. In addition, this pressure-sensitive adhesive composition does not have too high adhesive strength even if it is brought to a high temperature state before UV irradiation and then returned to room temperature, and excellent peelability is obtained after UV irradiation, and the adhesive remains on the adherend after peeling. It is difficult.

In the repeating unit k, R ¹ is -H or -CH ₃ and is preferably -H. R ⁵ is an alkyl group having 1 to 16 carbon atoms, preferably an alkyl group having 1 to 8 carbon atoms, and particularly preferably an alkyl group having 2, 4 or 8 carbon atoms.

The repeating unit k may be a plurality of repeating units from which ^{R 1} and R ^{5 are different.} When the repeating unit k contains a plurality of types of repeating units, the molar composition ratio k of the repeating unit k represents the sum of the molar composition ratios of the plurality of types of repeating units. For example, when the repeating unit k contains ^{repeating units A and B with different R 1} and/or R ⁵ , and the molar composition ratio of the repeating unit A is 2 mol% and the molar composition ratio of the repeating unit B is 3 mol% , The molar composition ratio k of the repeating number k is "5" by adding up the molar composition ratio of the repeating unit A and the repeating unit B.

In the repeating unit 1, R ² is -H or -CH ₃ , and it is preferable that it is -H. R ⁶ is an alicyclic hydrocarbon group having 3 to 30 carbon atoms or an aromatic hydrocarbon group having 6 to 20 carbon atoms, preferably an alicyclic hydrocarbon group having 6 to 20 carbon atoms or an aromatic hydrocarbon group having 6 to 10 carbon atoms.

The repeating unit l may be a plurality of repeating units from which ^{R 2} and R ^{6 are different.} When the repeating unit l contains a plurality of types of repeating units, the molar composition ratio l of the repeating unit l represents the sum of the molar composition ratios of the plurality of types of repeating units.

In the repeating unit m, R ³ is -H or -CH ₃ and is preferably -H. R ⁷ is -H or -(CH ₂ ) _j -COOH (wherein j is 1 or 2), and is preferably -H.

The repeating unit m may be a plurality of repeating units from which ^{R 3} and R ^{7 are different.} In this case, the molar composition ratio m of the repeating unit m represents the sum of the molar composition ratios of a plurality of types of repeating units.

In the repeating unit n, R ⁴ is -H or -CH ₃ and is preferably -H. R ⁸ is a formula (1-2) or (1-3). The groups represented by formula (1-2) or (1-3) all contain a structure derived from an alicyclic compound, and have a function of improving the heat resistance of the pressure-sensitive adhesive composition. In formula (1-2) or (1-3), p and q are any one selected from 0, 1, and 2. s is 0 when p is 0, and 1 when p is 1 or 2. R ⁹ is -H or -CH ₃ .

The repeating unit n may be a plurality of repeating units from which ^{R 4} and R ^{8 are different.} In this case, the molar composition ratio n of the repeating unit n represents the sum of the molar composition ratios of the plurality of repeating units.

Resin (A) represented by formula (1-1) is any of a repeating unit k, a repeating unit l, a repeating unit m, and a random copolymer including a repeating unit n, a block copolymer, and an alternating copolymer. You can do it. The resin (A) represented by formula (1-1) does not have to contain a repeating unit l, and a random copolymer, a block copolymer, and an alternating copolymer containing a repeating unit k, a repeating unit m, and a repeating unit n. Any of coalescence may be sufficient.

The weight average molecular weight of the resin (A) is preferably 200,000 to 1 million, and more preferably 300,000 to 800,000. When the weight average molecular weight of the resin (A) is 200,000 or more, when the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition is adhered to the adherend and then peeled, the pressure-sensitive adhesive layer is more difficult to remain on the adherend. . When the weight average molecular weight of the resin (A) is 1 million or less, the viscosity of the resin (A) does not become too high, and an effect of good workability is obtained. The weight average molecular weight of resin (A) is a value measured by the method described in Examples.

The glass transition temperature (Tg) of the resin (A) is preferably -80 to 0°C, more preferably -60 to -10°C, and more preferably -50 to -10°C. When the glass transition temperature of the resin (A) is in the range of -80°C to 0°C, the adhesive strength of the pressure-sensitive adhesive composition before UV irradiation becomes good. Tg of resin (A) is a value measured by the method described in Examples.

The acid value of the resin (A) is preferably more than 0 to 20 mgKOH/g, and more preferably 3 to 10 mgKOH/g. When the acid value of the resin (A) is in the range of more than 0 to 20 mgKOH/g, there is no contamination of the adherend after heating (remaining of an adhesive agent), and it becomes good. Further, when the pressure-sensitive adhesive composition contains a crosslinking agent, when the acid value of the resin (A) is within the above range, the resin (A) and the crosslinking agent react and the cohesive strength of the pressure-sensitive adhesive composition becomes good. The acid value of the resin (A) is a value measured by the method described in Examples.

(Production method of resin (A))

The resin (A) contained in the pressure-sensitive adhesive composition of the present embodiment can be produced, for example, by the method shown below.

First, a carboxyl group-containing ethylenically unsaturated monomer (a) and a raw material monomer including the ethylenically unsaturated monomer (d) are polymerized to prepare a carboxy group-containing resin (b). Here, the ethylenically unsaturated monomer (d) may contain a monomer that forms the repeating unit k after polymerization, and may contain a monomer that forms the skeleton of the repeating unit l.

Next, resin (A) is produced by addition reaction of the carboxy group-containing resin (b) and the specific alicyclic epoxy group-containing ethylenically unsaturated compound (c).

(Ethylenically unsaturated monomer containing carboxyl group (a))

The carboxy group-containing ethylenically unsaturated monomer (a) used when producing the carboxy group-containing resin (b) is a monomer that forms the skeleton of the repeating unit m by polymerization. The carboxyl group-containing ethylenically unsaturated monomer (a) has one carboxyl group.

As a carboxy group-containing ethylenically unsaturated monomer (a), (meth)acrylic acid, β-carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, etc. can be illustrated, for example.

Among these, as the carboxy group-containing ethylenically unsaturated monomer (a), it is preferable to use (meth)acrylic acid and/or β-carboxyethyl (meth)acrylate from the viewpoint of reactivity.

In this specification, (meth)acrylic means "acrylic" or "methacryl." (Meth)acrylate means "acrylate" or "methacrylate".

(Carboxy group-containing resin (b))

The carboxy group-containing resin (b) is a product obtained by copolymerizing a raw material monomer containing at least a carboxy group-containing ethylenically unsaturated monomer (a) and an ethylenically unsaturated monomer (d) copolymerizable with a carboxy group-containing ethylenically unsaturated monomer (a).

The carboxy group-containing resin (b) is a component that serves as the skeleton of the resin (A) represented by formula (1-1). The repeating unit k, the repeating unit l, and the repeating unit m are all repeating units derived from the carboxy group-containing resin (b).

As the ethylenically unsaturated monomer (d), one or more monomers that form the skeleton of the repeating unit k by polymerization are used. As the ethylenically unsaturated monomer (d), together with a monomer that forms a skeleton of the repeating unit k by polymerization, one or more monomers that form a skeleton of the repeating unit l by polymerization may be used.

The ethylenically unsaturated monomer (d) forming the skeleton of the repeating unit k by polymerization is an alkyl (meth)acrylate having 1 to 16 carbon atoms, and from the viewpoint of adjusting the peel strength of the pressure-sensitive adhesive composition, an alkyl having 2 to 16 carbon atoms ( It is preferable to contain a meth)acrylate, and it is more preferable to contain an alkyl (meth)acrylate having 4 to 12 carbon atoms. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) Acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, n-hexyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, and the like. . Among these, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isooctyl (meth) acrylate are preferred.

As an ethylenically unsaturated monomer (d) that forms the skeleton of the repeating unit l by polymerization, for example, a (meth)acrylate containing a cyclic alkyl group having 3 to 30 carbon atoms, a (meth)acrylate containing an aromatic group having 6 to 20 carbon atoms, etc. Can be mentioned.

Examples of the (meth)acrylate containing a cyclic alkyl group having 3 to 30 carbon atoms used as the ethylenically unsaturated monomer (d) forming the skeleton of the repeating unit 1 by polymerization include, for example, cyclohexyl (meth)acrylate, norbornyl ( Meth)acrylate, isobornyl(meth)acrylate, norbornanyl(meth)acrylate, dicyclopentenyl(meth)acrylate, dicyclopentenyloxyethyl(meth)acrylate, dicyclopentanyl(meth)acrylate )Acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclodecanedimethyloldi(meth)acrylate, and the like. Among these, it is particularly preferable to use isobornyl (meth)acrylate. When a cyclic alkyl (meth)acrylate is contained in the raw material monomer of the carboxyl group-containing resin (b), the heat resistance of the pressure-sensitive adhesive composition containing the resin (A) produced using the carboxy group-containing resin (b) becomes good.

Examples of the aromatic group-containing (meth)acrylate having 6 to 20 carbon atoms used as the ethylenically unsaturated monomer (d) forming the skeleton of the repeating unit l by polymerization include benzyl (meth)acrylate and phenoxyethyl (meth)acrylate. , Phenoxy polyethylene glycol (meth) acrylate, phenoxy propyl (meth) acrylate, phenoxy polypropylene glycol (meth) acrylate, and the like. Among these, it is particularly preferable to use benzyl (meth)acrylate. When an aromatic group-containing (meth)acrylate is contained in the raw material monomer of the carboxy group-containing resin (b), the heat resistance of the pressure-sensitive adhesive composition containing the resin (A) produced using the carboxy group-containing resin (b) becomes good.

Among the raw material monomers of the carboxyl group-containing resin (b), not only the carboxy group-containing ethylenically unsaturated monomer (a) and the ethylenically unsaturated monomer (d), but also a carboxyl group-containing ethylenically unsaturated monomer other than the ethylenically unsaturated monomer (d) A monomer copolymerizable with (a) may be contained.

Examples of ethylenically unsaturated monomers copolymerizable with a carboxyl group-containing ethylenically unsaturated monomer (a) other than the ethylenically unsaturated monomer (d) include alkoxyalkyl (meth)acrylate, alkoxy (poly)alkylene glycol (meth)acrylate, Hydroxy group-containing (meth)acrylate, fluorinated alkyl (meth)acrylate, dialkylaminoalkyl (meth)acrylate, (meth)acrylamide, and the like.

Examples of the alkoxyalkyl (meth)acrylate include ethoxyethyl (meth)acrylate, methoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, and 2-methoxyethoxyethyl (meth)acrylic. Rate, 2-ethoxyethoxyethyl (meth)acrylate, and the like.

Examples of the alkoxy (poly) alkylene glycol (meth) acrylate include methoxydiethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, and methoxydipropylene glycol (meth)acrylate. have.

Examples of the hydroxy group-containing (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 1,3-butanediol. (Meth)acrylate, 1,4-butanediol (meth)acrylate, 1,6-hexanediol (meth)acrylate, 3-methylpentanediol (meth)acrylate, and the like.

Examples of the fluorinated alkyl (meth)acrylate include octafluoropentyl (meth)acrylate.

Examples of the dialkylaminoalkyl (meth)acrylate include N,N-dimethylaminoethyl (meth)acrylate and N,N-diethylaminoethyl (meth)acrylate.

As (meth)acrylamide, for example, (meth)acrylamide, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-propyl (meth)acrylamide, N-isopropyl acrylamide, N-hexyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, (meth)acryloylmorpholine, diacetoneacrylamide, etc. are mentioned. .

As specific examples of monomers other than the above of the monomers copolymerizable with the carboxy group-containing ethylenically unsaturated monomer (a) other than the ethylenically unsaturated monomer (d), acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate, Vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, N-vinylpyridine, N-vinylpyrrolidone, itaconic acid dialkyl ester, fumaric acid dialkyl ester, allyl alcohol, hydroxybutyl Vinyl ether, hydroxyethyl vinyl ether, 4-hydroxymethylcyclohexylmethyl vinyl ether, triethylene glycol monovinyl ether or diethylene glycol monovinyl ether, methyl vinyl ketone, allyl trimethyl ammonium chloride, dimethyl allyl vinyl ketone, etc. I can.

It does not specifically limit as a method of manufacturing a carboxy group-containing resin (b).

For example, it is obtained by copolymerizing a raw material monomer containing a carboxy group-containing ethylenically unsaturated monomer (a) and an ethylenically unsaturated monomer (d) which is a constituent component of the carboxy group-containing resin (b) by a known polymerization method.

Specifically, as the polymerization method, a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, an alternating copolymerization method, or the like can be used. Among these polymerization methods, in consideration of the addition reaction of the carboxyl group-containing resin (b) obtained after polymerization and the alicyclic epoxy group-containing ethylenically unsaturated compound (c), it is preferable to use a solution polymerization method from the viewpoint of easiness of the reaction.

When producing a carboxy group-containing resin (b) by a solution polymerization method, a radical polymerization initiator and/or a solvent is used as necessary.

It does not specifically limit as a radical polymerization initiator, It can select and use suitably from known ones.

As a radical polymerization initiator, for example, 2,2'-azobis (isobutyronitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'- Azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2' -Azo polymerization initiators such as azobis (2,4,4-trimethylpentane) and dimethyl-2,2'-azobis (2-methylpropionate); Benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy)3,3,5- Oil-soluble polymerization initiators such as peroxide-based polymerization initiators such as trimethylcyclohexane and 1,1-bis(t-butylperoxy)cyclododecane are illustrated.

These radical polymerization initiators may be used alone or in combination of two or more.

The amount of the radical polymerization initiator used is preferably 0.01 to 5 parts by mass, more preferably 0.02 to 4 parts by mass, furthermore 0.03 to 3 parts by mass, based on 100 parts by mass of the total of the raw material monomers of the carboxy group-containing resin (b). desirable.

As the solvent for polymerization used when producing the carboxy group-containing resin (b), various general solvents can be used. Examples of the solvent include esters such as ethyl acetate, n-propyl acetate, and n-butyl acetate, aromatic hydrocarbons such as toluene, xylene, and benzene, aliphatic hydrocarbons such as n-hexane and n-heptane, cyclohexane, Alicyclic hydrocarbons such as methylcyclohexane, ketones such as methyl ethyl ketone and methyl isobutyl ketone, glycols such as ethylene glycol, propylene glycol, and dipropylene glycol, methyl cellosolve, propylene glycol monomethyl ether, dipropylene glycol And glycol esters such as glycol ethers such as monomethyl ether, ethylene glycol diacetate, and propylene glycol monomethyl ether acetate.

These solvents may be used alone or in combination of two or more.

When preparing the carboxy group-containing resin (b), the carboxyl group-containing ethylene in the raw material monomer containing the carboxy group-containing ethylenically unsaturated monomer (a), the ethylenically unsaturated monomer (d), and other monomers contained as necessary. It is preferable that the content of the unsaturated monomer (a) is 5 to 40 mass%, more preferably 7 to 30 mass%, and still more preferably 10 to 25 mass%. Resin (A) produced by addition reaction of a carboxy group-containing resin (b) and an alicyclic epoxy group-containing ethylenically unsaturated compound (c) by making the content of the carboxy group-containing ethylenically unsaturated monomer (a) in the above range The adhesive strength before UV irradiation of the adhesive layer obtained from the adhesive composition containing) becomes favorable.

(An alicyclic epoxy group-containing ethylenically unsaturated compound (c))

The alicyclic epoxy group-containing ethylenically unsaturated compound (c) is an ethylenically unsaturated group-containing compound having an alicyclic epoxy group, and is a compound giving a structure of the general formula (1-2) or (1-3). The alicyclic epoxy group in this embodiment refers to an epoxy group formed by bonding of one oxygen to two adjacent carbon atoms on the ring of the alicyclic hydrocarbon compound.

The alicyclic epoxy group-containing ethylenically unsaturated compound (c) is the following partial structural formula (1-2') or (1-3') in the repeating unit n of the photosensitive resin (A) represented by formula (1-1). Is used to add. The partial structural formula (1-2') or (1-3') in the repeating unit n in formula (1-1) is a group derived from an alicyclic epoxy group-containing ethylenically unsaturated compound (c).

(In formulas (1-2') and (1-3'), q is any one selected from 0, 1, and 2. R ⁹ is -H or -CH ₃ .)

As an alicyclic epoxy group-containing ethylenically unsaturated compound (c), the compound represented by following formula (1) or (2) is mentioned, for example.

(In formula (1), R ⁹ is -H or -CH _3. q is any one selected from 0, 1, and 2.)

(In formula (2), R ⁹ is -H or -CH _3. q is any one selected from 0, 1, and 2.)

In formula (1), R ⁹ is -H or -CH ₃ . q is any one selected from 0, 1, and 2, and it is preferable that q is 1.

In formula (2), R ⁹ is -H or -CH ₃ . q is any one selected from 0, 1, and 2, and it is preferable that q is 1.

As the alicyclic epoxy group-containing ethylenically unsaturated compound (c), it is preferable that it is a compound represented by formula (1), and it is particularly preferable to use 3,4-epoxycyclohexylmethyl (meth)acrylate.

The alicyclic epoxy group-containing ethylenically unsaturated compound (c) may be used alone or in combination of two or more.

The resin (A) of the present embodiment can be produced by adding an alicyclic epoxy group of the alicyclic epoxy group-containing ethylenically unsaturated monomer (c) to the carboxyl group of the carboxy group-containing resin (b).

Resin (A) is preferably 0.2 to 0.99 mol, more preferably 0.3 to 0.95 mol, still more preferably 0.6 to 0.95 mol of alicyclic epoxy group-containing ethylenically unsaturated with respect to 1 mol of the carboxyl group of the carboxy group-containing resin (b) It is preferably prepared by addition reaction of compound (c). A pressure-sensitive adhesive composition comprising a resin (A) obtained by using a carboxyl group-containing resin (b) and an alicyclic epoxy group-containing ethylenically unsaturated compound (c) in the above ratio, obtains sufficient adhesion to the adherend before UV irradiation, and UV After irradiation, the adhesive force is lowered, and more excellent peelability is obtained. In addition, this pressure-sensitive adhesive composition is difficult to increase the adhesive strength even if it is brought to a high temperature state before UV irradiation and then returned to room temperature, and excellent peelability is obtained after UV irradiation, and it is possible to more effectively prevent the residual pressure-sensitive adhesive on the adherend after peeling. have.

The temperature of the addition reaction in producing the resin (A) is preferably 80 to 130°C, and particularly preferably 90 to 120°C. When the temperature of the addition reaction is 80°C or higher, a sufficient reaction rate is obtained. When the temperature of the addition reaction is 130° C. or lower, the double bond portion is crosslinked by radical polymerization by heat, so that the formation of a gelled product can be prevented.

For the addition reaction in producing the resin (A), if necessary, a known catalyst can be used. As a catalyst, for example, triethylamine, tributylamine, dimethylbenzylamine, 1,8-diazabicyclo[5,4,0]undeca-7-ene, 1,5-diazabicyclo[4,3 Tertiary amines such as ,0]non-5-ene and 1,4-diazabicyclo[2,2,2]octane, quaternary ammonium salts such as tetramethylammonium chloride, tetramethylammonium bromide, and tetrabutylammonium bromide, Alkyl urea such as tetramethyl urea, alkyl guanidine such as tetramethylguanidine, triphenylphosphine, dimethylphenylphosphine, tricyclohexylphosphine, tributylphosphine, tris(4-methylphenyl)phosphine, tris(4- Methoxyphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine, tris(2,6-dimethoxyphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2, Phosphine compounds, such as 4,6-trimethoxyphenyl) phosphine, etc. are mentioned.

As the catalyst for the addition reaction, among the above, it is preferable to use a phosphine compound from the viewpoint of reactivity.

The amount of catalyst used in the addition reaction is preferably 0.01 to 30 parts by mass, more preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the total of the carboxy group-containing resin (b) and the alicyclic epoxy group-containing ethylenically unsaturated monomer (c). It is preferred, and 0.1 to 2 parts by mass is most preferred.

In addition, during the addition reaction, a gas having a polymerization inhibitory effect may be introduced into the reaction system or a polymerization inhibitor may be added. Gelation during the addition reaction can be prevented by introducing a gas having a polymerization inhibitory effect into the reaction system or adding a polymerization inhibitor.

As a gas having a polymerization inhibiting effect, a gas containing oxygen to a degree that does not enter the explosive range of the substance in the system, for example, air, and the like can be mentioned.

As the polymerization inhibitor, a known one can be used, and there is no particular limitation, but for example, 4-methoxyphenol, hydroquinone, metoquinone, 2,6-di-t-butylphenol, 2,2'-methylenebis (4-methyl-6-t-butylphenol), phenothiazine, and the like. These polymerization inhibitors may be used alone or in combination of two or more.

The amount of the polymerization inhibitor used is preferably 0.005 to 5 parts by mass, more preferably 0.03 to 3 parts by mass, based on 100 parts by mass of the total of the carboxy group-containing resin (b) and the alicyclic epoxy group-containing ethylenically unsaturated monomer (c), 0.05 to 1.5 parts by mass is most preferred. If the amount of the polymerization inhibitor is too small, the polymerization inhibitory effect may not be sufficient. On the other hand, if the amount of the polymerization inhibitor is too large, there is a fear that the exposure sensitivity of the resin (A) will decrease.

Further, when a gas having a polymerization inhibitory effect and a polymerization inhibitor are used together, the amount of the polymerization inhibitor to be used can be reduced or the polymerization inhibitory effect can be increased, and thus, it is more preferable.

(Photopolymerization initiator (B))

As the photoinitiator (B) contained in the pressure-sensitive adhesive composition, for example, benzophenone, benzyl, benzoin, ω-bromoacetophenone, chloroacetone, acetophenone, 2,2-diethoxyacetophenone, 2,2-dime Oxy-2-phenylacetophenone, p-dimethylaminoacetophenone, p-dimethylaminopropiophenone, 2-chlorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone, Michler's ketone, benzoin methyl ether, benzoin isobutyl ether, benzoin-n-butyl ether, benzyl methyl ketal, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane 1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, methylbenzoylformate, 2,2-diethoxyacetophenone, 4-N,N'- And carbonyl-based photopolymerization initiators such as dimethylacetophenone and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one.

Examples of the photopolymerization initiator (B) include sulfide-based photopolymerization initiators such as diphenyl disulfide, dibenzyl disulfide, tetraethylthiuram disulfide, and tetramethylammonium monosulfide; Acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide; Quinone photoinitiators such as benzoquinone and anthraquinone; Sulfochloride photopolymerization initiator; Thioxanthone photoinitiators, such as thioxanthone, 2-chloro thioxanthone, and 2-methyl thioxanthone, etc. may be used.

Among these photoinitiators (B), it is preferable to use 1-hydroxycyclohexylphenyl ketone and/or 2,4,6-trimethylbenzoyldiphenylphosphine oxide from the viewpoint of solubility in the pressure-sensitive adhesive composition.

The photopolymerization initiator (B) may be used alone or in combination of two or more.

The photopolymerization initiator (B) contained in the pressure-sensitive adhesive composition is preferably 0.1 to 5.0 parts by mass, and more preferably 0.5 to 2.0 parts by mass, based on 100 parts by mass of the resin (A). If the content of the photopolymerization initiator (B) relative to 100 parts by mass of the resin (A) is 0.1 parts by mass or more, the pressure-sensitive adhesive composition is cured at a sufficiently fast curing rate by UV irradiation, and the adhesive strength of the pressure-sensitive adhesive composition after UV irradiation becomes sufficiently small, desirable. When the content of the photoinitiator (B) is 5.0 parts by mass or less, when the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition is peeled after sticking to the adherend, it becomes difficult for the pressure-sensitive adhesive layer to remain on the adherend. Moreover, even if the content of the photoinitiator (B) exceeds 5.0 parts by mass, no effect corresponding to the content of the photoinitiator (B) is observed.

(Crosslinking agent (C))

The pressure-sensitive adhesive composition of the present embodiment may contain not only the resin (A) and the photopolymerization initiator (B) but also a crosslinking agent (C). By containing the crosslinking agent (C), the balance between the adhesive force before UV irradiation and the adhesive force after UV irradiation becomes a much better pressure-sensitive adhesive composition.

Although it does not specifically limit as a crosslinking agent (C), A compound which has 2 or more functional groups reactive with the hydroxyl group of repeating unit n, or the hydroxyl group of repeating unit n, and the carboxy group of repeating unit m is preferable.

As a crosslinking agent (C), for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenyl Methane-4,4-diisocyanate, isophorone diisocyanate, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane, hexa Isocyanurate of methylene diisocyanate, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, tolylene diisocyanate adduct of trimethylolpropane, xylylene diisocyanate adduct of trimethylolpropane, triphenylmethane tri Isocyanate compounds such as isocyanate and methylenebis(4-phenylmethane)triisocyanate,

Bisphenol A·epichlorohydrin type epoxy resin, N,N'-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine], 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, poly Epoxy compounds such as glycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether,

Tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'-bis(1-aziri Aziridine compounds such as dinecarboxyamide) and N,N'-hexamethylene-1,6-bis(1-aziridinecarboxyamide),

And melamine compounds such as hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, and hexahexyloxymethylmelamine.

Among these, as the crosslinking agent (C), since the reactivity with the resin (A) is good, it is preferable to use an epoxy compound and/or an isocyanate compound.

The crosslinking agent (C) may be used alone or in combination of two or more.

The crosslinking agent (C) contained in the pressure-sensitive adhesive composition is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and still more preferably 0.1 to 1.0 parts by mass, based on 100 parts by mass of the resin (A). When the content of the crosslinking agent (C) relative to 100 parts by mass of the resin (A) is 0.05 parts by mass or more, a three-dimensional crosslinked structure is sufficiently formed in the pressure-sensitive adhesive composition. As a result, the adhesive force of the pressure-sensitive adhesive composition after UV irradiation becomes sufficiently small, which is preferable. When the content of the crosslinking agent (C) with respect to 100 parts by mass of the resin (A) is 10 parts by mass or less, the adhesive strength of the pressure-sensitive adhesive composition before UV irradiation becomes good.

(Other ingredients)

The pressure-sensitive adhesive composition of the present embodiment may contain other components other than the resin (A), the photopolymerization initiator (B), and the crosslinking agent (C) described above, if necessary.

As another component, a tackifier, a solvent, various additives, etc. are mentioned.

(Adhesion imparting agent)

As the tackifier, a conventionally known one can be used without particular limitation. As tackifier, for example, terpene tackifier resin, phenol tackifier resin, rosin tackifier resin, aliphatic petroleum resin, aromatic petroleum resin, copolymerized petroleum resin, alicyclic petroleum resin, xylene resin, epoxy System tackifier resin, polyamide system tackifier resin, ketone system tackifier resin, elastomer system tackifier resin, etc. are mentioned. These tackifiers may be used alone or in combination of two or more.

When the pressure-sensitive adhesive composition of the present embodiment contains a tackifier, the content is preferably 30 parts by mass or less, and more preferably 5 to 20 parts by mass, based on 100 parts by mass of the resin (A).

(menstruum)

The solvent can be used to dilute the pressure-sensitive adhesive composition for the purpose of adjusting the viscosity of the pressure-sensitive adhesive composition when coating the pressure-sensitive adhesive composition.

As a solvent, for example, methyl ethyl ketone, methyl isobutyl ketone, acetone, ethyl acetate, n-propyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene, n-propanol, isopropanol, etc. Organic solvents of can be used. These solvents may be used alone or in combination of two or more.

(additive)

Examples of additives include plasticizers, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, light stabilizers such as benzotriazoles, phosphoric acid esters and other flame retardants, and charging such as surfactants. Inhibitors, etc. are mentioned.

[Method of manufacturing adhesive composition]

The pressure-sensitive adhesive composition of the present embodiment can be produced by a conventionally known method.

For example, by mixing the resin (A) and the photopolymerization initiator (B) described above, and the crosslinking agent (C), tackifier, solvent, and various additives contained as needed, using a conventionally known method, followed by stirring. Can be manufactured.

The pressure-sensitive adhesive composition of the present embodiment is suitable as a material for forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet. In particular, the pressure-sensitive adhesive composition of the present embodiment is preferable as a material for forming the pressure-sensitive adhesive layer of the re-peelable pressure-sensitive adhesive sheet.

Since the pressure-sensitive adhesive composition of the present embodiment contains the resin (A) represented by the formula (1-1) and a photopolymerization initiator (B), by using it as a material for forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, the adherend is A pressure-sensitive adhesive sheet having sufficient adhesive strength is obtained. In addition, even if the adherend to which the pressure-sensitive adhesive sheet is attached is brought back to room temperature to be peeled off, after UV irradiation, excellent peelability is obtained, and residual pressure-sensitive adhesive is less likely to occur.

``Adhesive sheet''

The adhesive sheet of the present invention has a sheet-like substrate and an adhesive layer formed on the substrate.

It is preferable that a release sheet (separator) is provided on the surface of the pressure-sensitive adhesive layer opposite to the base material. When the release sheet is provided on the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer can be protected by the release sheet until use. In addition, when the release sheet is provided on the pressure-sensitive adhesive layer, the release sheet is peeled to expose the pressure-sensitive adhesive layer, and the work of compressing the pressure-sensitive adhesive layer (attached surface) to the adherend can be efficiently performed.

The pressure-sensitive adhesive sheet of the present embodiment may be used as a pressure-sensitive adhesive tape having a shape corresponding to the shape of an adherend by a punching method or the like. Moreover, the adhesive sheet of this embodiment may be used as an adhesive tape by winding up and cutting.

As the substrate, a known sheet-like material can be appropriately selected and used. As the substrate, it is preferable to use a resin sheet containing a transparent resin material.

Examples of the resin material include polyolefins such as polyethylene (PE) and polypropylene (PP); Polyester sheets such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate; Polyvinyl chloride (PVC); Polyimide (PI); Polyphenylene sulfide (PPS); Ethylene vinyl acetate (EVA); And polytetrafluoroethylene (PTFE). Among these resin materials, since a sheet having moderate flexibility can be obtained, it is preferable to use PE, PP, or PET. Resin material may be used individually by 1 type, and may mix and use 2 or more types.

When using a resin sheet as a base material, a single layer may be sufficient as a resin sheet, and a multilayer structure (for example, a three-layer structure) of two or more layers may be sufficient as it. In a resin sheet having a multilayer structure, the resin material constituting each layer may be a resin material containing only one type or may be a resin material containing two or more types.

The thickness of the substrate can be appropriately selected according to the use of the pressure-sensitive adhesive sheet, the material of the substrate, and the like. The pressure-sensitive adhesive sheet protects the wafer when performing the dicing process of the wafer, and when a resin sheet is used as the base material, the thickness of the base material is, for example, preferably 10 to 1000 µm, more preferably 50 to It is 300 μm. When the thickness of the substrate is 10 µm or more, the rigidity of the pressure-sensitive adhesive sheet becomes high (the stiffness becomes strong). Therefore, when the pressure-sensitive adhesive sheet is affixed to an adherend such as a wafer or peeled from the adherend, there is a tendency that wrinkles and lifting are less likely to occur in the pressure-sensitive adhesive sheet. In addition, when the thickness of the substrate is 10 µm or more, the pressure-sensitive adhesive sheet attached to the adherend is easily peeled from the adherend, and workability (handleability, handling) becomes good. When the thickness of the base material is 1000 µm or less, the rigidity of the pressure-sensitive adhesive sheet becomes too high (the stiffness becomes too strong) and the workability can be prevented from deteriorating.

When a resin sheet is used as the substrate, a conventionally known general sheet molding method (e.g., extrusion molding, T-die molding, inflation molding, etc., or uniaxial or biaxial stretching molding, etc.) is appropriately employed to prepare the substrate. I can.

Surface treatment for improving the adhesion between the substrate and the pressure-sensitive adhesive layer may be applied to the surface of the substrate on the side in contact with the pressure-sensitive adhesive layer.

Examples of the surface treatment include corona discharge treatment, acid treatment, ultraviolet irradiation treatment, plasma treatment, and primer (primer) coating.

The pressure-sensitive adhesive layer included in the pressure-sensitive adhesive sheet of the present embodiment contains the pressure-sensitive adhesive composition described above.

The thickness of the pressure-sensitive adhesive layer is preferably 1 to 100 µm, more preferably 2 to 80 µm, and even more preferably 5 to 50 µm. When the thickness of the pressure-sensitive adhesive layer is 1 μm or more, the uniformity of the thickness of the pressure-sensitive adhesive layer becomes good. On the other hand, when the thickness of the pressure-sensitive adhesive layer is 100 μm or less, it is preferable because the solvent can be easily removed even when the pressure-sensitive adhesive layer is formed using a solvent.

When a release sheet is provided on the side opposite to the substrate of the pressure-sensitive adhesive layer, a known sheet-like material can be appropriately selected and used as the release sheet. As the release sheet, the same resin sheet as the above-described resin sheet used as a substrate can be used.

The thickness of the release sheet can be appropriately selected depending on the use of the pressure-sensitive adhesive sheet, the material of the release sheet, and the like. When a resin sheet is used as the release sheet, the thickness of the release sheet is, for example, preferably 5 to 300 µm, more preferably 10 to 200 µm, and still more preferably 25 to 100 µm.

The release surface of the release sheet (the surface disposed in contact with the adhesive layer) may be subjected to a release treatment using a conventionally known release agent such as silicone-based, long-chain alkyl-based, or fluorine-based, if necessary.

[Method of manufacturing adhesive sheet]

The adhesive sheet of this embodiment can be manufactured, for example by the method shown below.

First, a pressure-sensitive adhesive solution obtained by dissolving or dispersing the aforementioned pressure-sensitive adhesive composition in a solvent is prepared. The pressure-sensitive adhesive composition described above may be used as it is as a pressure-sensitive adhesive solution.

Next, the pressure-sensitive adhesive solution is applied on the substrate and dried by heating to form a pressure-sensitive adhesive layer. After that, it is obtained by bonding a release sheet on the pressure-sensitive adhesive layer as necessary.

In addition, as another method of manufacturing the pressure-sensitive adhesive sheet of the present embodiment, the pressure-sensitive adhesive solution is applied onto a release sheet, and then dried by heating to form a pressure-sensitive adhesive layer. Thereafter, a method of installing a release sheet having an adhesive layer on a substrate, with the surface on the side of the adhesive layer facing the substrate, and transferring (depositioning) the adhesive layer onto the substrate may be mentioned.

As a method of applying the pressure-sensitive adhesive solution onto a substrate (or a release sheet), a known method can be used. Specifically, a method of applying using a conventional coater, for example, a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, a direct coater, etc. I can.

[Use of adhesive sheet]

The pressure-sensitive adhesive sheet of the present embodiment can be used as a re-peelable pressure-sensitive adhesive sheet. The adhesive sheet of this embodiment can be used, for example, when manufacturing an electronic component. Specifically, in each step of manufacturing an electronic component, the pressure-sensitive adhesive sheet of the present embodiment fixes the adherend, applies it to various processing steps, and then removes the adherend by irradiation with ultraviolet rays (UV), It is used for recovery purposes. Therefore, the pressure-sensitive adhesive sheet of the present embodiment can be used as a backgrind tape, a dicing tape, or the like when processing a semiconductor wafer. In addition, the pressure-sensitive adhesive sheet of the present embodiment can be suitably used as a support tape for fragile members such as ultrathin glass substrates, plastic films, flexible printed circuit boards (FPC substrates), and the like. In particular, the pressure-sensitive adhesive sheet of the present embodiment is suitable as a dicing tape for protecting a wafer when performing a dicing process for a wafer.

When using the pressure-sensitive adhesive sheet of the present embodiment as a dicing tape for a wafer, before performing the dicing process, the pressure-sensitive adhesive sheet is affixed to the wafer on which a plurality of parts are formed. Next, the wafer is cut, separated into individual parts (diced), and formed into elemental pieces (chips). After that, UV is irradiated to the pressure-sensitive adhesive sheet affixed on each element element piece. Thereby, UV is irradiated to the pressure-sensitive adhesive layer through the base material of the pressure-sensitive adhesive sheet, and the unsaturated bond in the pressure-sensitive adhesive forms a three-dimensional crosslinked structure and is cured. As a result, the adhesive force of the pressure-sensitive adhesive layer is lowered. After that, the adhesive sheet is peeled from the top of each element element.

Examples of light sources used when UV irradiation is applied to the adhesive sheet before peeling attached to the adherend include high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, chemical lamps, black lights, and the like. .

It is preferable that it is 50-3000 mJ/cm<2>, and, as for the UV irradiation amount irradiated to an adhesive sheet, it is more preferable that it is 100-600 mJ/cm<2>. When the amount of UV irradiation irradiated to the pressure-sensitive adhesive sheet is 50 mJ/cm 2 or more, the pressure-sensitive adhesive layer is cured at a sufficiently fast curing speed by UV irradiation, and the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer after UV irradiation is sufficiently small, which is preferable. Even if the amount of UV irradiation irradiated to the pressure-sensitive adhesive sheet is 3000 mJ/cm 2 or more, no corresponding effect is obtained.

Example

Hereinafter, the present invention will be described in more detail by examples and comparative examples. In addition, the present invention is not limited only to the following examples.

"Production of resin (A)"

(Production Example 1)

[Preparation of the first mixed solution]

As shown in Table 1, 23.9 parts by mass of acrylic acid as an ethylenically unsaturated monomer (a) containing a carboxyl group, 71.8 parts by mass of n-butyl acrylate as an ethylenically unsaturated monomer (d) copolymerizable with the above (a) and 2-ethyl The first mixture containing 0.1 parts by mass of 2,2'-azobisisobutyronitrile, which is a polymerization initiator, based on 100 parts by mass of the total of 100 parts by mass of the raw material monomer containing 143.6 parts by mass of hexyl acrylate and the raw material monomer of the carboxy group-containing resin (b). A solution was prepared.

[Preparation of the second mixed solution]

As shown in Table 1, 59.8 parts by mass of 3,4-epoxycyclohexylmethylmethacrylate, which is an alicyclic epoxy group-containing ethylenically unsaturated compound (c), and a carboxy group-containing resin (b), and an alicyclic epoxy group-containing ethylenically unsaturated monomer A second mixed solution containing 0.6 parts by mass of tris(4-methylphenyl)phosphine (TPTP) as a catalyst, 100.0 parts by mass of n-butyl acetate and 91.1 parts by mass of toluene as a solvent was prepared based on 100 parts by mass of the total of (c). I did.

To a four-necked flask equipped with a stirrer, a dropping funnel, a cooling tube, and a nitrogen introduction tube, 175.6 parts by mass of n-butyl acetate was added as a solvent, and the temperature was raised to 80°C in a nitrogen gas atmosphere. And, while maintaining the reaction temperature at 80°C±2°C, the first mixed solution was uniformly added dropwise to the four-necked flask over 4 hours, and after the dropping was completed, the mixture was stirred at a temperature of 80°C±2°C for 6 hours. Subsequently, the carboxyl group-containing resin (b) was polymerized. Thereafter, 0.15 parts by mass of 4-methoxyphenol was added to the reaction system as a polymerization inhibitor with respect to 100 parts by mass in total of the carboxy group-containing resin (b) and the alicyclic epoxy group-containing ethylenically unsaturated monomer (c).

The reaction system to which 4-methoxyphenol was added was heated to 100° C., and the second mixed solution was added dropwise over 0.5 hours, followed by stirring at a temperature of 100° C. for 8 hours to synthesize resin (A-1). And cooled to room temperature (23° C.).

When resin (A-1) was identified by the nuclear magnetic resonance method (NMR method), it was a compound represented by the general formula (2-1). The repeating unit k in the formula (1-1) in the compound represented by the general formula (2-1) is two kinds of repeating units (k-1, k-2) having different ^{R 5.}

(In formula (2-1), k-1 is 34, k-2 is 47, m is 1, and the sum of k-1, k-2 and m is 82. n is 18.)

About resin (A-1), the weight average molecular weight and glass transition temperature were investigated by the method shown below. In addition, the acid value of the resin (A-1) was measured according to JIS K0070. The results are shown in Table 3.

<Weight average molecular weight (Mw)>

Using gel permeation chromatography (Showa Denko Corporation, Shodex (registered trademark) GPC-101), it was measured at room temperature under the following conditions, and calculated in terms of polystyrene.

Column: Showa Denko Corporation, Shodex (registered trademark) LF-804

Column temperature: 40°C

Sample: 0.2 mass% tetrahydrofuran solution of resin (A)

Flow: 1 ml/min

Eluent: tetrahydrofuran

Detector: RI detector

<Glass transition temperature (Tg)>

A 10 mg sample was taken from the resin (A). Using a differential scanning calorimeter (DSC), differential scanning calorimetry was performed by changing the temperature of the sample from -100°C to 200°C at a temperature increase rate of 10°C/min, and the endothermic start temperature due to the observed glass transition as Tg. I did. In addition, when two Tg were observed, it was set as the simple average value of two Tg.

(Production Examples 2 to 8, 10 to 12)

In the content (parts by mass) shown in Tables 1 and 2, except for using a carboxyl group-containing ethylenically unsaturated monomer (a), an ethylenically unsaturated monomer (d), and a polymerization initiator, the first A mixed solution was prepared.

In addition, in the content (parts by mass) shown in Tables 1 and 2, except for using an alicyclic epoxy group-containing ethylenically unsaturated compound (c) (glycidyl methacrylate (GMA) in Production Example 8) and a catalyst. In the same manner as in Production Example 1, a second mixed solution was prepared.

Except having used the said 1st mixed solution and the said 2nd mixed solution, it carried out similarly to Production Example 1, and obtained resins (A-2) to (A-8) (A-10) to (A-12).

Resins (A-2) to (A-8) (A-10) to (A-12) were identified in the same manner as in Preparation Example 1, respectively, and as a result, General Formulas (2-2) to (2-8) (2 It was a compound represented by -10) to (2-12). The repeating unit k in the formula (1-1) in the compound represented by the general formulas (2-2) to (2-8) (2-10) is R ⁵ or both of ^{R 1} and R ⁵ It is the other two kinds of repeating units (k-1, k-2).

Resin (A-2) is a compound represented by the following general formula (2-2).

Resin (A-3) is a compound represented by the following general formula (2-3).

Resin (A-4) is a compound represented by the following general formula (2-4).

Resin (A-5) is a compound represented by the general formula (2-5).

Resin (A-6) is a compound represented by the following general formula (2-6).

Resin (A-7) is a compound represented by the following general formula (2-7).

Resin (A-8) is a compound represented by the following general formula (2-8).

Resin (A-10) is a compound represented by the following general formula (2-10).

Resin (A-11) is a compound represented by the following general formula (2-11).

Resin (A-12) is a compound represented by the following general formula (2-12).

(In formula (2-2), k-1 is 32, k-2 is 48, m is 1, and the sum of k-1, k-2 and m is 81. n is 19.)

(In formula (2-3), k-1 is 70, k-2 is 16, m is 1, and the sum of k-1, k-2 and m is 87. n is 13.)

(In formula (2-4), k-1 is 52, k-2 is 34, m is 3, and the sum of k-1, k-2 and m is 89. n is 11.)

(In formula (2-5), k-1 is 11, k-2 is 52, m is 4, the sum of k-1, k-2 and m is 67, and n is 33.)

(In formula (2-6), k-1 is 56, k-2 is 24, m is 0.2, and the sum of k-1, k-2 and m is 80.2. n is 19.8.)

(In formula (2-7), k-1 is 15, k-2 is 72, m is 1, and the sum of k-1, k-2 and m is 88. n is 12.)

(In formula (2-8), k-1 is 37, k-2 is 44, m is 2, and the sum of k-1, k-2 and m is 83. n'is 17. )

(In formula (2-10), k-1 is 34, k-2 is 47, m is 4, and the sum of k-1, k-2 and m is 85. n is 15.)

(In formula (2-11), k is 66, l is 12, m is 2, and the sum of k, l, and m is 80. n is 20.)

(In formula (2-12), k is 55, l is 23, m is 2, and the sum of k, l, and m is 80. n is 20.)

About resins (A-2) to (A-8) (A-10) to (A-12), the weight average molecular weight, glass transition temperature, and acid value were investigated in the same manner as the photosensitive resin (A-1), respectively. . The results are shown in Table 3.

(Production Example 9)

In the content (parts by mass) shown in Table 2, except for using a carboxyl group-containing ethylenically unsaturated monomer (a), an ethylenically unsaturated monomer (d), and a polymerization initiator, a first mixed solution was prepared in the same manner as in Production Example 1. Prepared.

To a four-neck flask equipped with a stirrer, a dropping funnel, a cooling tube, and a nitrogen introduction tube, 261.7 parts by mass of ethyl acetate was added as a solvent, followed by heating and refluxing. After heating to reflux, the first mixed solution described in Table 2 was uniformly added dropwise over 4 hours, and after the dropwise addition, stirring was continued for 6 hours by heating and refluxing. Thereafter, the reaction system was cooled to 60° C., and polymerization was prohibited with respect to 286.4 parts by mass of ethyl acetate as a solvent, and 100 parts by mass of the total of the carboxy group-containing resin (b) and 2-isocyanatoethyl methacrylate (MOI) described later. 0.15 parts by mass of 4-methoxyphenol as a zero, 0.3 dioctyltin dilaurate as a catalyst based on 100 parts by mass of the total of the resin (b) containing a carboxyl group and 2-isocyanatoethyl methacrylate (MOI) described later. It was added in parts by mass.

After the 4-methoxyphenol was dissolved, 47.8 parts by mass of 2-isocyanatoethyl methacrylate (MOI) was added to the reaction system, and stirring was continued at 60° C. for 8 hours to synthesize a resin (A-9). , Cooled to room temperature (23° C.).

When resin (A-9) was identified in the same manner as in Production Example 1, it was a compound represented by General Formula (2-9). The repeating unit k in the formula (1-1) in the compound represented by the general formula (2-9) is two kinds of repeating units (k-1, k-2) having different ^{R 5.}

(In formula (2-9), k-1 is 48, k-2 is 32, m is 1, and the sum of k-1, k-2 and m is 81. j is 2, and n '' is 17.)

About resin (A-9), it carried out similarly to resin (A-1), and the weight average molecular weight, glass transition temperature, and acid value were investigated. The results are shown in Table 3.

In addition, for resins (A-1) to (A-12), k-1, k-2, k (sum of k-1 and k-2) in formulas (2-1) to (2-12), respectively ), l, m, n, n', n'' are shown in Table 3.

Tables 1 and 2 show a carboxy group-containing ethylenically unsaturated monomer (a) used in the production of resins (A-1) to (A-12), and an ethylenically unsaturated monomer (d) copolymerizable with the above (a), Polymerization initiator, alicyclic epoxy group-containing ethylenically unsaturated compound (c), catalyst, polymerization inhibitor, and type and amount of solvent (parts by mass), glycidyl methacrylate (GMA) and 2-isocyanatoethyl The amount (parts by mass) of methacrylate (MOI) is shown, respectively.

"Examples 1 to 12, Comparative Examples 1 to 2"

To the reaction solution of the resins (A-1) to (A-12) synthesized in Preparation Examples 1 to 12, ethyl acetate as a solvent was added, and the content of the resins (A-1) to (A-12) was 30 It adjusted so that it might become mass %. Using the resin (A-1) to (A-12) solution in which the content of the resins (A-1) to (A-12) is 30% by mass, a pressure-sensitive adhesive composition was obtained by the method shown below.

In a plastic container in a room where active rays are blocked, the resin (A), the photopolymerization initiator (B), and the crosslinking agent (C) shown in Tables 4 to 6 were added in the contents (parts by mass) shown in Tables 4 to 6, respectively. It was added and stirred to obtain the pressure-sensitive adhesive compositions of Examples 1 to 12 and Comparative Examples 1 to 2.

The numerical values of the resins (A-1) to (A-12) in Tables 4 to 6 are the resins (A-1) to (A) in which the content of the resins (A-1) to (A-12) is 30% by mass. -12) It is the amount of solution used (parts by mass). The numerical value of the photoinitiator (B) is the used amount (part by mass) of the photoinitiator (B) with respect to 100 parts by mass of the resin (A). The numerical value of the crosslinking agent (C) is the amount (parts by mass) of the crosslinking agent (C) with respect to 100 parts by mass of the resin (A).

"TETRAD-C" "HX" "TPO" in Tables 4 to 6, and "TETRAD-X" in Tables 4 and 5 are shown below, respectively.

「TETRAD-C」 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., brand name: TETRAD-C)

"TETRAD-X" N,N'-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine] (manufactured by Mitsubishi Gas Chemical Co., Ltd., brand name: TETRAD- X)

"HX" isocyanurate body of hexamethylene diisocyanate (manufactured by Tosoh Corporation, brand name: Coronate (registered trademark) HX)

"TPO" 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by BASF, brand name: L-TPO)

"Production of adhesive sheet"

The pressure-sensitive adhesive compositions of Examples 1 to 12 and Comparative Examples 1 to 2 were coated on a substrate so that the film thickness after drying became 20 μm, and heated and dried at 100° C. for 2 minutes to form a pressure-sensitive adhesive layer. Thereafter, by bonding the release sheet on the pressure-sensitive adhesive layer, the pressure-sensitive adhesive sheets of Examples 1 to 12 and Comparative Examples 1 to 2 were obtained. As the base material and the release sheet, a 50 µm-thick polyethylene terephthalate (PET) film was used.

With respect to the pressure-sensitive adhesive sheets of Examples 1 to 12 and Comparative Examples 1 to 2 thus obtained, the items shown below were evaluated by the method shown below. The results are shown in Tables 4 to 6.

``Peel strength before UV irradiation''

The pressure-sensitive adhesive sheet was cut into a size of 25 mm in length and 100 mm in width, and the release sheet was peeled to expose the pressure-sensitive adhesive layer. Next, the pressure-sensitive adhesive sheet was affixed to the glass plate so that the exposed pressure-sensitive adhesive layer (measurement surface) was in contact with the glass plate, and a 2 kg rubber roller (width: about 50 mm) was repeated once to measure the peel strength before UV irradiation. It was taken as a sample.

The obtained sample for measurement was allowed to stand for 24 hours in an environment at a temperature of 23°C and a humidity of 50%. Then, in accordance with JIS Z0237, a tensile test in the 180° direction was performed at a peel rate of 300 mm/min, and the peel strength (N/25 mm) of the pressure-sensitive adhesive sheet with respect to the glass plate was measured.

"Peel strength after UV irradiation"

The same thing as the sample for measuring peel strength before UV irradiation was prepared, and ultraviolet (UV) irradiation was carried out from the surface of the pressure-sensitive adhesive sheet side under conditions of an irradiation amount of 500 mJ/cm 2 to obtain a sample for measuring peel strength after UV irradiation. For UV irradiation, a conveyor-type ultraviolet irradiation apparatus (manufactured by Eye Graphics, 2KW lamp, 80W/cm) was used.

About the obtained sample for measurement, it carried out similarly to "Peel strength before UV irradiation", and measured the peel strength (N/25 mm) with respect to the glass plate of an adhesive sheet.

``Peel strength after heat-resistant UV irradiation''

Prepare the same sample as the sample for measuring the peel strength before UV irradiation, heat treatment at 200°C for 2 hours, cool to room temperature (23°C), and irradiate UV under the same conditions as “Peel strength after UV irradiation”. , After heat-resistant UV irradiation, it was set as a sample for measuring the peel strength.

About the obtained sample for measurement, it carried out similarly to "Peel strength after UV irradiation", and measured the peel strength (N/25 mm) with respect to the glass plate of an adhesive sheet.

``Remaining adhesive''

After performing the measurement of the peel strength after UV irradiation, the glass plate was visually observed and evaluated according to the following criteria. The results are shown in Tables 4 to 6.

(Evaluation standard)

○: No adhesive remains on the glass plate.

?: The adhesive remained on a part of the glass plate.

X: The adhesive remained on the entire surface of the glass plate.

As shown in Table 4 and Table 5, all of the PSA sheets of Examples 1 to 12 had a "peel strength before UV irradiation" of 1.0 N/25 mm or more, and a "peel strength after heat-resistant UV irradiation" of 2.5 N/25. It was less than mm, and the evaluation of residual adhesive was ○ or △.

On the other hand, as shown in Table 6, the pressure-sensitive adhesive sheets of Comparative Example 1 and Comparative Example 2 in which the resin (A) does not contain a structure derived from an alicyclic compound, even though the ``peel strength after UV irradiation'' was sufficiently low. Nevertheless, "the peeling strength after heat-resistant UV irradiation" was high, and the evaluation of the adhesive residual was ×.

Claims (7)

A pressure-sensitive adhesive composition comprising a resin (A) represented by the following general formula (1-1) and a photoinitiator (B).

(In formula (1-1), k, l, m, and n represent the molar composition ratio when k+l+m+n=100. k is more than 0 and not more than 92. l is 0 to 92 50. m is greater than 0 and not more than 90. The sum of k, l and m is 65 to 95. n is 5 to 35. R ¹ to R ⁴ are -H or -CH _3. R ⁵ is a number of carbon atoms It is an alkyl group of 1 to 16. R ⁶ is an alicyclic hydrocarbon group having 3 to 30 carbon atoms or an aromatic hydrocarbon group having 6 to 20 carbon atoms. R ⁷ is -H or -(CH ₂ ) _j -COOH (wherein j is 1 Or 2. R ⁸ is the general formula (1-2) or (1-3). In formulas (1-2) and (1-3), p and q are from 0, 1, 2 Which is selected, s is 0 when p is 0, 1 when p is 1 or 2. R ⁹ is -H or -CH ₃ .) The method of claim 1,
The pressure-sensitive adhesive composition, characterized in that the weight average molecular weight of the resin (A) is 200,000 to 1 million. The method according to claim 1 or 2,
The pressure-sensitive adhesive composition in which n in the formula (1-1) is 10 to 33. The method according to any one of claims 1 to 3,
The pressure-sensitive adhesive composition, wherein k in the formula (1-1) is 45 to 90, l is 4 to 40, and m is 1 to 15. The method according to any one of claims 1 to 4,
A pressure-sensitive adhesive composition further containing a crosslinking agent (C). The method according to any one of claims 1 to 5,
The pressure-sensitive adhesive composition, characterized in that the glass transition temperature of the resin (A) is -80 to 0 ℃. A pressure-sensitive adhesive sheet comprising a sheet-like substrate and a pressure-sensitive adhesive layer formed on the substrate, wherein the pressure-sensitive adhesive layer contains the pressure-sensitive adhesive composition according to any one of claims 1 to 6.