Dicing tape

Abstract

To provide an adhesive agent composition and an adhesive agent sheet, that have an enough adhesive force against an adhered body, return a temperature of the adhered body to which the adhesive sheet is adhered to a room temperature after it becomes a high temperature, can obtain an excellent easy peeling property even if it is peeled after an UV irradiation, and can obtain the adhesive sheet in which an adhesive residue is hardly generated.SOLUTION: An adhesive agent component contains a resin and a photoinitiator, expressed by a formula (1-1). In the formula, R1 to R4 are -H or -CH3, R5 is an alkyl group of the number of 1 to 16 of carbons, R6 is an alicyclic hydrocarbon group or an aromatic hydrocarbon group, R7 is -H or -(CH2)j-COOH (j is 1 or 2 in the formula), and R8 is a specific group.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an adhesive composition and an adhesive sheet. This application claims priority based on Japanese Patent Application No. 2018-164843 filed in Japan on September 3, 2018, the content of which is incorporated herein by reference.

Background Art

[0002] Conventionally, various adhesive sheets have been used in semiconductor manufacturing processes and the like. Specifically, there are a protective sheet for protecting a wafer in the back grinding process of a semiconductor wafer, a fixing sheet used in the dicing process of cutting and dividing a semiconductor wafer into element chips, and the like. These adhesive sheets are re-peelable adhesive sheets that are attached to a semiconductor wafer as an adherend and peeled from the adherend after a predetermined processing step is completed. As an adhesive composition used for the adhesive layer of a re-peelable adhesive sheet, those containing a resin having an ethylenically unsaturated group in the molecule and being cured by UV (ultraviolet rays) are known.

[0003] Patent Document 1 discloses a step of reacting a (meth)acrylic polymer having two or more hydroxyl groups in the side chain with a compound having an isocyanato group in the presence of a first catalyst to form a (meth)acrylic polymer having a urethane bond, and a step of reacting the (meth)acrylic polymer having a urethane bond with a compound having two or more isocyanato groups in one molecule in the presence of a second catalyst to form an adhesive layer, wherein the first catalyst is a complex of at least one metal selected from zirconium, titanium, and aluminum, and the second catalyst is an amine-based catalyst. A method for manufacturing an adhesive sheet is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] A re-peelable pressure-sensitive adhesive sheet is required to have sufficient adhesiveness to an adherend when performing a predetermined processing step, to be easily peelable (easy peelability) from the adherend after the predetermined processing step is completed, and not to have the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet transferred (no glue residue) to the adherend after peeling. However, conventional pressure-sensitive adhesive sheets did not satisfy all of the above conditions. In particular, when the pressure-sensitive adhesive sheet is attached to an adherend, the adherend is processed at a high temperature of about 200°C, and then peeled off by UV irradiation, there has been a problem that glue residue is likely to occur.

[0006] 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 adhesiveness to the adherend, and after the adherend to which the pressure-sensitive adhesive sheet is attached is brought to a high temperature state and then returned to room temperature and peeled off after UV irradiation, it is an object to provide a pressure-sensitive adhesive composition that can obtain excellent easy peelability and is less likely to cause glue residue. Another object of the present invention is to provide a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the above pressure-sensitive adhesive composition.

Means for Solving the Problems

[0007] In order to solve the above problems, the present inventor has conducted intensive studies. As a result, a resin (A) obtained by an addition reaction between 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 a photopolymerization initiator (B) It has been found that a pressure-sensitive adhesive composition containing as essential components may be used.

[0008] The pressure-sensitive adhesive composition containing a resin (A) and a 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, when irradiated with ultraviolet rays (UV), unsaturated bonds in the resin (A) form a three-dimensional crosslinked structure and cure, changing the adhesive strength. Specifically, sufficient adhesive strength can be obtained with respect to the adherend before irradiating the pressure-sensitive adhesive composition with UV, and after irradiating with UV, the adhesive strength decreases to obtain excellent peelability, and residue of the adhesive on the adherend after peeling can be sufficiently prevented. Based on such findings, the present inventors arrived at the present invention. That is, the present invention relates to the following matters.

[0009] [1] A pressure-sensitive adhesive composition comprising a resin (A) represented by the following general formula (1-1) and a photoinitiator (B).

[0010] [Chemical formula]

[0011] [Chemical formula] (In formula (1-1), k, l, m, and n represent molar composition ratios 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 from 65 to 95. n is from 5 to 35. R 1 ~R 4 is -H or -CH 3 . R 5 is an alkyl group having 1 to 16 carbon atoms. 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 (j in the formula is 1 or 2). R 8is the above general formula (1-2) or (1-3). In formulas (1-2) and (1-3), p and q are each selected from 0, 1, and 2. s is 0 when p is 0, and s is 1 when p is 1 or 2. R 9 is -H or -CH 3 .)

[0012] [2] The pressure-sensitive adhesive composition according to [1], wherein the weight-average molecular weight of the resin (A) is from 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 from 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 from 45 to 90, l is from 4 to 40, and m is from 1 to 15.

[0013] [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 from -80 to 0°C.

[0014] [7] A pressure-sensitive adhesive sheet having 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 [1] to [6].

Advantages of the Invention

[0015] By using the pressure-sensitive adhesive composition of the present invention as a material for forming the pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet, the pressure-sensitive adhesive sheet has sufficient adhesive force to an adherend. Even when the adherend with the pressure-sensitive adhesive sheet attached is heated to a high temperature and then returned to room temperature and peeled off after UV irradiation, an excellent peelability is obtained, and a pressure-sensitive adhesive sheet with little adhesive residue is obtained.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, the pressure-sensitive adhesive composition and the pressure-sensitive adhesive sheet of the present invention will be described in detail. Note that the present invention is not limited only to the embodiments shown below. "Adhesive Composition" The adhesive composition of this embodiment contains a resin (A) and a photoinitiator (B). (Resin (A)) The resin (A) contained in the adhesive composition of this embodiment is a compound represented by the following general formula (1-1).

[0017]

Chemical formula

[0018]

Chemical formula

[0019] In formula (1-1), k, l, m, and n represent the molar composition ratios 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 from 65 to 95. When the sum of k, l, and m is 65 or more, an adhesive composition can obtain sufficient adhesiveness to the adherend before UV irradiation. The sum of k, l, and m is preferably from 70 to 94, and more preferably from 80 to 90.

[0020] In formula (1-1), the repeating unit (hereinafter referred to as "repeating unit k") shown in the parentheses enclosed by k is an essential repeating unit. Repeating unit k contributes to the adhesive strength of the adhesive composition before UV irradiation. The number of repetitions k of repeating unit k is greater than 0 and less than or equal to 92, preferably from 45 to 90, and more preferably from 60 to 88.

[0021] In formula (1-1), the repeating unit (hereinafter referred to as "repeating unit l") shown in the parentheses enclosed by l may not be present. In other words, the number of repetitions of repeating unit l may be 0. Repeating unit l contributes to the heat resistance of the adhesive composition. The number of repetitions l of repeating unit l is from 0 to 50, preferably from 4 to 40, and more preferably from 5 to 30.

[0022] In formula (1-1), the repeating unit (hereinafter referred to as "repeating unit m") shown in the parentheses enclosed by m is an essential repeating unit. Repeating unit m contributes to the adhesive strength and heat resistance of the adhesive composition before UV irradiation. Also, when the adhesive composition contains a crosslinking agent having a functional group that reacts with a carboxy group, repeating unit m reacts with the crosslinking agent to improve the cohesive strength of the adhesive composition. The number of repetitions m of repeating unit m is greater than 0 and less than or equal to 90, preferably from 1 to 15, and more preferably from 1 to 5.

[0023] In formula (1-1), the repeating unit (hereinafter referred to as "repeating unit n") shown within the parentheses enclosed 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 from 5 to 35, preferably from 10 to 33, and more preferably from 10 to 20. When the repeating unit n is 35 or less, the unsaturated bonds in the resin (A) form a three-dimensional crosslinked structure upon UV irradiation and harden, resulting in a pressure-sensitive adhesive composition in which the adhesive strength decreases to an appropriate range. Further, when n is 5 or more, an effect of improving heat resistance due to the structure derived from the alicyclic compound can be obtained.

[0024] Due to the synergistic effect of the functions contributed by these repeating units, the pressure-sensitive adhesive composition containing the resin (A) has an even better balance between the adhesive strength before UV irradiation and the adhesive strength after UV irradiation. As a result, a sufficient adhesive strength can be obtained for the adherend before UV irradiation, and after UV irradiation, the adhesive strength decreases to obtain a pressure-sensitive adhesive composition with more excellent peelability. Moreover, this pressure-sensitive adhesive composition does not have too high an adhesive strength even when it is heated to a high temperature and then returned to room temperature before UV irradiation, and excellent peelability can be obtained after UV irradiation, and there is little glue residue on the adherend after peeling.

[0025] 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.

[0026] The repeating unit k may be a plurality of different types of repeating units of R 1 , R 5 . 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 is R 1 and / or R 5When it contains different repeating units A and B, 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 the sum of the molar composition ratios of the repeating unit A and the repeating unit B, which is "5".

[0027] In the repeating unit l, R 2 is -H or -CH 3 and preferably -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, and 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 2 a plurality of different types of repeating units of R 6 . When the repeating unit l contains a plurality of types of repeating units, the molar composition ratio l of the repeating unit l indicates the sum of the molar composition ratios of the plurality of types of repeating units.

[0028] In the repeating unit m, R 3 is -H or -CH 3 and preferably -H. R 7 is -H or -(CH 2 ) j -COOH (j in the formula is 1 or 2), and preferably -H. The repeating unit m may be 3 a plurality of different types of repeating units of R 7 . In this case, the molar composition ratio m of the repeating unit m indicates the sum of the molar composition ratios of the plurality of types of repeating units.

[0029] In the repeating unit n, R 4 is -H or -CH 3 and preferably -H. R 8is represented by formula (1-2) or (1-3). The groups represented by formula (1-2) or (1-3) both contain a structure derived from an alicyclic compound and have the function of improving the heat resistance of the pressure-sensitive adhesive composition. In formula (1-2) or (1-3), p and q are each independently selected from 0, 1, and 2. s is 0 when p is 0, and s is 1 when p is 1 or 2. R 9 is -H or -CH 3 . The repeating unit n may be a plurality of different repeating units of R 4 , R 8 . 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 different repeating units.

[0030] The resin (A) represented by formula (1-1) may be any of a random copolymer, a block copolymer, and an alternating copolymer composed of the repeating unit k, the repeating unit l, the repeating unit m, and the repeating unit n. The resin (A) represented by formula (1-1) may not contain the repeating unit l, and may be any of a random copolymer, a block copolymer, and an alternating copolymer composed of the repeating unit k, the repeating unit m, and the repeating unit n.

[0031] The weight average molecular weight of the resin (A) is preferably from 200,000 to 1,000,000, more preferably from 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 a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition is peeled off after being attached to an adherend, the pressure-sensitive adhesive layer is less likely to remain on the adherend. When the weight average molecular weight of the resin (A) is 1,000,000 or less, the viscosity of the resin (A) does not become too high, and the effect of good workability can be obtained. The weight average molecular weight of the resin (A) is the value measured by the method described in the examples.

[0032] The glass transition temperature (Tg) of the resin (A) is preferably from -80 to 0 °C, more preferably from -60 to -10 °C, still more preferably from -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 adhesive composition before UV irradiation becomes good. The Tg of the resin (A) is the value measured by the method described in the examples. The acid value of the resin (A) is preferably more than 0 to 20 mgKOH / g, 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 (adhesive residue) after heating and it is good. Further, when the 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 adhesive composition becomes good. The acid value of the resin (A) is the value measured by the method described in the examples.

[0033] (Method for producing the resin (A)) The resin (A) contained in the adhesive composition of this embodiment can be produced, for example, by the method shown below. First, a raw material monomer containing a carboxy group-containing ethylenically unsaturated monomer (a) and an ethylenically unsaturated monomer (d) is polymerized to produce a carboxy group-containing resin (b). Here, the ethylenically unsaturated monomer (d) may contain a monomer that forms a repeating unit k and a monomer that forms a skeleton of a repeating unit l after polymerization. Next, the resin (A) is produced by an addition reaction between the carboxy group-containing resin (b) and a specific alicyclic epoxy group-containing ethylenically unsaturated compound (c).

[0034] (Carboxy group-containing ethylenically unsaturated monomer (a)) The carboxy group-containing ethylenically unsaturated monomer (a) used for producing the carboxy group-containing resin (b) is a monomer that forms a skeleton of a repeating unit m by polymerization. The carboxy group-containing ethylenically unsaturated monomer (a) has one carboxy group. Examples of the carboxy group-containing ethylenically unsaturated monomer (a) include (meth)acrylic acid, β-carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, and the like. 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.

[0035] In this specification, (meth)acrylic means "acrylic" or "methacrylic". (meth)acrylate means "acrylate" or "methacrylate".

[0036] (Carboxy group-containing resin (b)) The carboxy group-containing resin (b) is obtained by copolymerizing at least a raw material monomer containing a carboxy group-containing ethylenically unsaturated monomer (a) and an ethylenically unsaturated monomer (d) copolymerizable with the carboxy group-containing ethylenically unsaturated monomer (a). The carboxy group-containing resin (b) is a component that forms the skeleton of the resin (A) represented by the 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).

[0037] 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), one or more monomers that form the skeleton of the repeating unit l by polymerization may be used together with the monomer that forms the skeleton of the repeating unit k by polymerization.

[0038] The ethylenically unsaturated monomer (d) that forms the backbone of the repeating unit k by overlapping 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, it preferably contains an alkyl (meth) acrylate having 2 to 16 carbon atoms, and more preferably contains 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, etc. can be mentioned. Among these, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isooctyl (meth) acrylate are preferable.

[0039] Examples of the ethylenically unsaturated monomer (d) that forms the backbone of the repeating unit l by polymerization include (meth) acrylates containing a cyclic alkyl group having 3 to 30 carbon atoms, (meth) acrylates containing an aromatic group having 6 to 20 carbon atoms, and the like.

[0040] Examples of the C3-30 cyclic alkyl group-containing (meth)acrylate used as the ethylenically unsaturated monomer (d) that forms the backbone of the repeating unit l by polymerization include cyclohexyl (meth)acrylate, norbornyl (meth)acrylate, isobornyl (meth)acrylate, norbornanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyl oxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentanyl oxyethyl (meth)acrylate, tricyclodecane dimethylol di(meth)acrylate, and the like. Among these, it is particularly preferable to use isobornyl (meth)acrylate. When the raw material monomer of the carboxy group-containing resin (b) contains a cyclic alkyl (meth)acrylate, the heat resistance of the pressure-sensitive adhesive composition containing the resin (A) produced using the carboxy group-containing resin (b) becomes good.

[0041] Examples of the C6-20 aromatic group-containing (meth)acrylate used as the ethylenically unsaturated monomer (d) that forms the backbone of the repeating unit l by polymerization include benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxy polypropylene glycol (meth)acrylate, and the like. Among these, it is particularly preferable to use benzyl (meth)acrylate. When the raw material monomer of the carboxy group-containing resin (b) contains an aromatic group-containing (meth)acrylate, the heat resistance of the pressure-sensitive adhesive composition containing the resin (A) produced using the carboxy group-containing resin (b) becomes good.

[0042] In the raw material monomer of the carboxy group-containing resin (b), not only the above-mentioned carboxy group-containing ethylenically unsaturated monomer (a) and the above-mentioned ethylenically unsaturated monomer (d), but also monomers copolymerizable with the carboxy group-containing ethylenically unsaturated monomer (a) other than the above-mentioned ethylenically unsaturated monomer (d) may be included.

[0043] Examples of the ethylenically unsaturated monomer copolymerizable with the carboxy group-containing ethylenically unsaturated monomer (a) other than the above-described 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.

[0044] Examples of the alkoxyalkyl (meth)acrylate include ethoxyethyl (meth)acrylate, methoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, 2-methoxyethoxyethyl (meth)acrylate, 2-ethoxyethoxyethyl (meth)acrylate, and the like.

[0045] Examples of the alkoxy(poly)alkylene glycol (meth)acrylate include methoxydiethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, and the like.

[0046] Examples of the hydroxy group-containing (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1,3-butanediol (meth)acrylate, 1,4-butanediol (meth)acrylate, 1,6-hexanediol (meth)acrylate, 3-methylpentanediol (meth)acrylate, and the like.

[0047] Examples of the fluorinated alkyl (meth)acrylate include octafluoropentyl (meth)acrylate and the like. Examples of the dialkylaminoalkyl (meth)acrylate include N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, and the like.

[0048] Examples of the (meth)acrylamide include (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-isopropylacrylamide, N-hexyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, (meth)acryloylmorpholine, diacetoneacrylamide, and the like.

[0049] Specific examples other than those described above of the monomer copolymerizable with the carboxy group-containing ethylenically unsaturated monomer (a) other than the ethylenically unsaturated monomer (d) include acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, N-vinylpyridine, N-vinylpyrrolidone, dialkyl itaconate, dialkyl fumarate, allyl alcohol, hydroxybutyl vinyl ether, hydroxyethyl vinyl ether, 4-hydroxymethylcyclohexylmethyl vinyl ether, triethylene glycol monovinyl ether or diethylene glycol monovinyl ether, methyl vinyl ketone, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, and the like.

[0050] The method for producing the carboxy group-containing resin (b) is not particularly limited. For example, it can be obtained by copolymerizing a raw material monomer containing a carboxy group-containing ethylenically unsaturated monomer (a) and an ethylenically unsaturated monomer (d) which are constituent components 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 between the carboxy group-containing resin (b) obtained after polymerization and the alicyclic epoxy group-containing ethylenically unsaturated compound (c), it is preferable to use the solution polymerization method in terms of ease of reaction.

[0051] When producing the carboxyl group-containing resin (b) by the solution polymerization method, a radical polymerization initiator and / or a solvent is used as necessary. The radical polymerization initiator is not particularly limited and can be appropriately selected from known ones for use. Examples of the radical polymerization initiator include azo-based polymerization initiators such as 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'-azobis(2,4,4-trimethylpentane), dimethyl-2,2'-azobis(2-methylpropionate); peroxide-based polymerization initiators such as benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclododecane, etc., and oil-soluble polymerization initiators are exemplified.

[0052] 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, and even more preferably 0.03 to 3 parts by mass, based on 100 parts by mass in total of the raw material monomers of the carboxyl group-containing resin (b).

[0053] As the polymerization solvent used in the production of the carboxyl group-containing resin (b), various common 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; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; ketones such as methyl ethyl ketone and methyl isobutyl ketone; glycols such as ethylene glycol, propylene glycol, and dipropylene glycol; glycol ethers such as methyl cellosolve, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether; and glycol esters such as ethylene glycol diacetate and propylene glycol monomethyl ether acetate. These solvents may be used alone or in combination of two or more.

[0054] In the production of the carboxyl group-containing resin (b), the content of the carboxyl group-containing ethylenically unsaturated monomer (a) in the raw material monomers containing the carboxyl group-containing ethylenically unsaturated monomer (a), the ethylenically unsaturated monomer (d), and other monomers contained as necessary is preferably 5 to 40% by mass, more preferably 7 to 30% by mass, and even more preferably 10 to 25% by mass. By setting the content of the carboxyl group-containing ethylenically unsaturated monomer (a) in the raw material monomers within the above range, the adhesive force before UV irradiation of the adhesive layer obtained from the adhesive composition containing the resin (A) produced by the addition reaction of the carboxyl group-containing resin (b) and the alicyclic epoxy group-containing ethylenically unsaturated compound (c) becomes good.

[0055] (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 having a structure represented by the general formula (1-2) or the general formula (1-3). The alicyclic epoxy group in the present embodiment refers to an epoxy group formed by bonding one oxygen atom to two adjacent carbon atoms on the ring of an alicyclic hydrocarbon compound. The alicyclic epoxy group-containing ethylenically unsaturated compound (c) is used to add the following partial structural formula (1-2’) or (1-3’) in the repeating unit n of the photosensitive resin (A) represented by the formula (1-1). The partial structural formula (1-2’) or (1-3’) in the repeating unit n in the formula (1-1) is a group derived from the alicyclic epoxy group-containing ethylenically unsaturated compound (c).

[0056] [Chemical formula] (In the formulas (1-2’) and (1-3’), q is any one selected from 0, 1, and 2. R 9 is -H or -CH 3 .)

[0057] Examples of the alicyclic epoxy group-containing ethylenically unsaturated compound (c) include compounds represented by the following formula (1) or (2).

[0058] [Chemical formula] (In the formula (1), R 9 is -H or -CH 3 . q is any one selected from 0, 1, and 2.) (In the formula (2), R 9 is -H or -CH 3 . q is any one selected from 0, 1, and 2.)

[0059] In the formula (1), R 9 is -H or -CH 3It is so. q is any one selected from 0, 1, and 2, and q is preferably 1. In formula (2), R 9 is -H or -CH 3 It is so. q is any one selected from 0, 1, and 2, and q is preferably 1.

[0060] As the alicyclic epoxy group-containing ethylenically unsaturated compound (c), the compound represented by formula (1) is preferable, and in particular, it is 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.

[0061] The resin (A) of the present embodiment can be produced by subjecting the alicyclic epoxy group of the alicyclic epoxy group-containing ethylenically unsaturated monomer (c) to an addition reaction with the carboxy group of the carboxy group-containing resin (b). The resin (A) is preferably produced by subjecting 0.2 to 0.99 mol, more preferably 0.3 to 0.95 mol, and still more preferably 0.6 to 0.95 mol of the alicyclic epoxy group-containing ethylenically unsaturated compound (c) to an addition reaction with respect to 1 mol of the carboxy group of the carboxy group-containing resin (b). The pressure-sensitive adhesive composition containing the resin (A) obtained by using the carboxy group-containing resin (b) and the alicyclic epoxy group-containing ethylenically unsaturated compound (c) in the above ratio has sufficient adhesiveness to the adherend before UV irradiation, and the adhesive strength decreases after UV irradiation to obtain better peelability. Moreover, this pressure-sensitive adhesive composition is less likely to have an increased adhesive strength even when it is heated to a high temperature and then returned to room temperature before UV irradiation, and excellent peelability can be obtained after UV irradiation, and the residue of the adhesive on the adherend after peeling can be more effectively prevented.

[0062] When producing the resin (A), the temperature of the addition reaction is preferably 80 to 130 °C, particularly preferably 90 to 120 °C. When the temperature of the addition reaction is 80 °C or higher, a sufficient reaction rate can be obtained. When the temperature of the addition reaction is 130 °C or lower, crosslinking of the double bond portion due to thermal radical polymerization can be prevented, and the formation of a gelled product can be avoided.

[0063] In the addition reaction for producing the resin (A), a known catalyst can be used as necessary. Examples of the catalyst include tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5-diazabicyclo[4.3.0]nona-5-ene, 1,4-diazabicyclo[2.2.2]octane; quaternary ammonium salts such as tetramethylammonium chloride, tetramethylammonium bromide, tetrabutylammonium bromide; alkylureas such as tetramethylurea; alkylguanidines such as tetramethylguanidine; phosphine compounds such as 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(2,4,6-trimethoxyphenyl)phosphine. Among the above, it is preferable to use a phosphine compound as the catalyst for the addition reaction in terms of reactivity.

[0064] The amount of the catalyst used in the addition reaction is preferably 0.01 to 30 parts by mass, more preferably 0.05 to 5 parts by mass, and most preferably 0.1 to 2 parts by mass with respect to a total of 100 parts by mass of the carboxyl group-containing resin (b) and the alicyclic epoxy group-containing ethylenically unsaturated monomer (c).

[0065] Furthermore, 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. By introducing a gas having a polymerization inhibitory effect into the reaction system or adding a polymerization inhibitor, gelation during the addition reaction can be prevented. Examples of the gas having a polymerization inhibitory effect include gases containing oxygen to such an extent that they do not fall within the explosion range of substances in the system, such as air.

[0066] As the polymerization inhibitor, known ones can be used and there is no particular limitation. For example, 4-methoxyphenol, hydroquinone, methoquinone, 2,6-di-t-butylphenol, 2,2'-methylenebis(4-methyl-6-t-butylphenol), phenothiazine, etc. can be mentioned. These polymerization inhibitors may be used alone or in combination of two or more.

[0067] 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, and most preferably 0.05 to 1.5 parts by mass with respect to a total of 100 parts by mass of the carboxy group-containing resin (b) and the alicyclic epoxy group-containing ethylenically unsaturated monomer (c). 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, the exposure sensitivity of the resin (A) may decrease. Moreover, it is more preferable to use a gas having a polymerization inhibitory effect and a polymerization inhibitor in combination because the amount of the polymerization inhibitor used can be reduced or the polymerization inhibitory effect can be enhanced.

[0068] (Photoinitiator (B)) Examples of the photoinitiator (B) contained in the pressure-sensitive adhesive composition include carbonyl photoinitiators such as benzophenone, benzyl, benzoin, ω-bromoacetophenone, chloroacetone, acetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-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-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, methyl benzoylformate, 2,2-diethoxyacetophenone, 4-N,N'-dimethylacetophenone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, etc.

[0069] Examples of the photoinitiator (B) also include sulfide photoinitiators such as diphenyl disulfide, dibenzyl disulfide, tetraethylthiuram disulfide, and tetramethylammonium monosulfide; acylphosphine oxides such as 2,4,6-trimethylbenzoyl diphenylphosphine oxide and 2,4,6-trimethylbenzoyl phenylethoxyphosphine oxide; quinone photoinitiators such as benzoquinone and anthraquinone; sulfochloride photoinitiators; and thioxanthone photoinitiators such as thioxanthone, 2-chlorothioxanthone, and 2-methylthioxanthone. These may be used.

[0070] Among these photoinitiators (B), from the viewpoint of solubility in the pressure-sensitive adhesive composition, it is preferable to use 1-hydroxycyclohexyl phenyl ketone and / or 2,4,6-trimethylbenzoyl diphenylphosphine oxide. The above photoinitiator (B) may be used alone or in combination of two or more.

[0071] The photoinitiator (B) contained in the pressure-sensitive adhesive composition is preferably 0.1 to 5.0 parts by mass, more preferably 0.5 to 2.0 parts by mass, based on 100 parts by mass of the resin (A). When the content of the photoinitiator (B) is 0.1 part by mass or more based on 100 parts by mass of the resin (A), the pressure-sensitive adhesive composition cures 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, which is preferable. When the content of the photoinitiator (B) is 5.0 parts by mass or less, when the pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition is peeled off after being attached to the adherend, the pressure-sensitive adhesive layer hardly remains on the adherend. Further, even when the content of the photoinitiator (B) exceeds 5.0 parts by mass, no effect commensurate with the content of the photoinitiator (B) is observed.

[0072] (Crosslinking agent (C)) The pressure-sensitive adhesive composition of the present embodiment may contain not only the resin (A) and the photoinitiator (B) but also a crosslinking agent (C). By containing the crosslinking agent (C), the pressure-sensitive adhesive composition having an even better balance between the adhesive strength before UV irradiation and the adhesive strength after UV irradiation is obtained. The crosslinking agent (C) is not particularly limited, but a compound having two or more functional groups reactive with the hydroxyl group of the repeating unit n or the hydroxyl group of the repeating unit n and the carboxyl group of the repeating unit m is preferable.

[0073] Examples of the crosslinking agent (C) include isocyanate compounds such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane, the isocyanurate form of hexamethylene diisocyanate, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, the tolylene diisocyanate adduct of trimethylolpropane, the xylylene diisocyanate adduct of trimethylolpropane, triphenylmethane triisocyanate, and methylenebis(4-phenylmethane)triisocyanate, epoxy resins of the bisphenol A - epichlorohydrin type, 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, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether and other epoxy compounds, aziridine compounds such as tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, N,N′-diphenylmethane-4,4′-bis(1-aziridinecarboxamide), and N,N′-hexamethylene-1,6-bis(1-aziridinecarboxamide), and melamine compounds such as hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, and hexapentyloxymethylmelamine.

[0074] 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 above crosslinking agent (C) may be used alone or in combination of two or more.

[0075] 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 even more preferably 0.1 to 1.0 parts by mass with respect to 100 parts by mass of the resin (A). When the content of the crosslinking agent (C) with respect 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 strength 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 is good.

[0076] (Other components) The pressure-sensitive adhesive composition of the present embodiment may contain other components other than the above-described resin (A), photopolymerization initiator (B), and crosslinking agent (C) as necessary. Examples of other components include tackifiers, solvents, and various additives.

[0077] (Tackifier) As the tackifier, conventionally known ones can be used without particular limitation. Examples of the tackifier include terpene-based tackifying resins, phenol-based tackifying resins, rosin-based tackifying resins, aliphatic petroleum resins, aromatic petroleum resins, copolymerized petroleum resins, alicyclic petroleum resins, xylene resins, epoxy-based tackifying resins, polyamide-based tackifying resins, ketone-based tackifying resins, elastomer-based tackifying resins, and the like. These tackifiers may be used alone or in combination of two or more.

[0078] When the pressure-sensitive adhesive composition of the present embodiment contains a tackifier, its content is preferably 30 parts by mass or less, more preferably 5 to 20 parts by mass, based on 100 parts by mass of the resin (A).

[0079] (Solvent) 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 the solvent, for example, organic solvents such as methyl ethyl ketone, methyl isobutyl ketone, acetone, ethyl acetate, n-propyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene, n-propanol, and isopropanol can be used. These solvents may be used alone or in combination of two or more.

[0080] (Additive) Examples of the additive include plasticizers, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, light stabilizers such as benzotriazole-based ones, phosphate ester-based and other flame retardants, and antistatic agents such as surfactants.

[0081] [Method for producing the pressure-sensitive adhesive composition] The pressure-sensitive adhesive composition of the present embodiment can be produced by a conventionally known method. For example, it can be produced by mixing and stirring the above-described resin (A) and photoinitiator (B), and optionally contained crosslinking agent (C), tackifier, solvent, and various additives using a conventionally known method.

[0082] 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 preferably used as a material for forming the pressure-sensitive adhesive layer of a re-peelable pressure-sensitive adhesive sheet. Since the pressure-sensitive adhesive composition of the present embodiment contains a resin (A) represented by the formula (1-1) and a photoinitiator (B), by using it as a material for forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet having sufficient adhesive force to the adherend can be obtained. Moreover, even when the adherend to which the pressure-sensitive adhesive sheet is attached is heated to a high temperature and then returned to room temperature and peeled off, excellent peelability can be obtained after UV irradiation, and residue of the adhesive is less likely to occur.

[0083] "Pressure-sensitive adhesive sheet" The pressure-sensitive adhesive sheet of the present invention has a sheet-like base material and a pressure-sensitive adhesive layer formed on the base material. 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 until use by the release sheet. Further, when the release sheet is provided on the pressure-sensitive adhesive layer, the operation of peeling off the release sheet to expose the pressure-sensitive adhesive layer and pressing the pressure-sensitive adhesive layer (adhesive surface) against 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 the adherend by a punching method or the like. Further, the pressure-sensitive adhesive sheet of the present embodiment may be used as a pressure-sensitive adhesive tape by winding and cutting.

[0084] As the base material, a known sheet-like material can be appropriately selected and used. As the base material, it is preferable to use a resin sheet made of 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); polytetrafluoroethylene (PTFE). Among these resin materials, since a sheet having appropriate flexibility can be obtained, it is preferable to use PE, PP, or PET. The resin material may be used alone or in combination of two or more.

[0085] When using a resin sheet as the base material, the resin sheet may be a single layer or a multilayer structure of two or more layers (for example, a three-layer structure). In a resin sheet having a multilayer structure, the resin material constituting each layer may be a resin material containing only one type alone or a resin material containing two or more types.

[0086] The thickness of the base material can be appropriately selected according to the use of the adhesive sheet, the material of the base material, etc. When the adhesive sheet is used to protect the wafer during the dicing process of the wafer and a resin sheet is used as the base material, the thickness of the base material is preferably, for example, 10 to 1000 μm, more preferably 50 to 300 μm. When the thickness of the base material is 10 μm or more, the rigidity of the adhesive sheet becomes high (the firmness is strong). Therefore, when the adhesive sheet is attached to an adherend such as a wafer or peeled from the adherend, wrinkles and bulges are less likely to occur in the adhesive sheet. Also, when the thickness of the base material is 10 μm or more, it becomes easier to peel the adhesive sheet attached to the adherend from the adherend, and the workability (handleability, handling) becomes good. When the thickness of the base material is 1000 μm or less, it is possible to prevent the rigidity of the adhesive sheet from becoming too high (the firmness is too strong) and the workability from deteriorating.

[0087] When using a resin sheet as the base material, a conventionally known general sheet forming method (for example, extrusion molding, T-die molding, inflation molding, etc. or uniaxial or biaxial stretching molding, etc.) can be appropriately adopted to manufacture the base material.

[0088] A surface treatment for improving the adhesiveness between the base material and the adhesive layer may be applied to the surface of the base material on the side in contact with the adhesive layer. Examples of the surface treatment include corona discharge treatment, acid treatment, ultraviolet irradiation treatment, plasma treatment, application of an undercoat agent (primer), etc.

[0089] The adhesive layer of the adhesive sheet of the present embodiment contains the above-described adhesive composition. The thickness of the 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 adhesive layer is 1 μm or more, the uniformity of the thickness of the adhesive layer becomes good. On the other hand, when the thickness of the adhesive layer is 100 μm or less, even when the adhesive layer is formed using a solvent, it is preferable because the solvent can be easily removed.

[0090] When a release sheet is provided on the surface of the adhesive layer opposite to the base material, as the release sheet, a known sheet-like material can be appropriately selected and used. As the release sheet, the same material as the above-described resin sheet used as the base material can be used. The thickness of the release sheet can be appropriately selected according to the use of the adhesive sheet, the material of the release sheet, etc. When a resin sheet is used as the release sheet, the thickness of the release sheet is preferably, for example, 5 to 300 μm, more preferably 10 to 200 μm, and even more preferably 25 to 100 μm.

[0091] 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 a silicone-based, long-chain alkyl-based, or fluorine-based release agent as necessary.

[0092] [Method for manufacturing an adhesive sheet] The adhesive sheet of the present embodiment can be manufactured, for example, by the method shown below. First, an adhesive solution in which the above-described adhesive composition is dissolved or dispersed in a solvent is prepared. The above-described adhesive composition may be used as the adhesive solution as it is. Next, the adhesive solution is applied onto the base material and dried by heating to form an adhesive layer. Thereafter, it can be obtained by laminating a release sheet on the adhesive layer as necessary. As another method for manufacturing the adhesive sheet of the present embodiment, the above-described adhesive solution is applied onto the release sheet and dried by heating to form an adhesive layer. Thereafter, a method of placing the release sheet having the adhesive layer on the base material with the surface of the adhesive layer side facing the base material and transferring (adhering) the adhesive layer onto the base material can be mentioned.

[0093] As a method for applying the above adhesive solution onto a substrate (or onto a release sheet), known methods can be used. Specifically, conventional coaters such as 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. can be used for coating.

[0094] [Applications of the Adhesive Sheet] The adhesive sheet of the present embodiment can be used as a re - peelable adhesive sheet. The adhesive sheet of the present embodiment can be used, for example, when manufacturing electronic components. Specifically, in each step of manufacturing electronic components, the adherend is fixed, and after being subjected to various processing steps, ultraviolet rays (UV) are irradiated to peel off and recover the adherend. Therefore, the adhesive sheet of the present embodiment can be used as a back - grinding tape, a dicing tape, etc. when processing semiconductor wafers. Further, the adhesive sheet of the present embodiment can be suitably used as a support tape for fragile members such as ultra - thin glass substrates, plastic films, and easily warped members such as flexible printed circuit boards (FPC boards). In particular, the adhesive sheet of the present embodiment is suitable as a dicing tape for protecting wafers when performing the dicing process of wafers.

[0095] When the adhesive sheet of the present embodiment is used as a dicing tape for wafers, before performing the dicing process, the adhesive sheet is attached to a wafer on which a plurality of components are formed. Next, the wafer is cut and separated (diced) into individual components to obtain element chips (chips). Then, the adhesive sheet attached on each element chip is irradiated with UV. As a result, the adhesive layer is irradiated with UV through the substrate of the adhesive sheet, and the unsaturated bonds in the adhesive form a three - dimensional cross - linked structure and cure. As a result, the adhesive force of the adhesive layer decreases. Then, the adhesive sheet is peeled off from each element chip.

[0096] As a light source used when performing UV irradiation on an adhesive sheet before peeling, which is attached to an adherend, examples include a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a chemical lamp, a black light, and the like. The UV irradiation dose for irradiating the adhesive sheet is preferably 50 to 3000 mJ / cm 2 and more preferably 100 to 600 mJ / cm 2 When the UV irradiation dose for irradiating the adhesive sheet is 50 mJ / cm 2 or more, the adhesive layer cures at a sufficiently fast curing rate by UV irradiation, and the adhesive strength of the adhesive layer after UV irradiation becomes sufficiently small, which is preferable. Even if the UV irradiation dose for irradiating the adhesive sheet is made 3000 mJ / cm 2 or more, an effect commensurate with that cannot be obtained.

Examples

[0097] Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. Note that the present invention is not limited only to the following Examples.

[0098] "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, which is a carboxy group-containing ethylenically unsaturated monomer (a), 71.8 parts by mass of n-butyl acrylate, which is an ethylenically unsaturated monomer (d) copolymerizable with the above (a), and 143.6 parts by mass of 2-ethylhexyl acrylate, and 0.1 part by mass of 2,2'-azobisisobutyronitrile, which is a polymerization initiator, were contained in a first mixed solution prepared with respect to a total of 100 parts by mass of the raw material monomers of the raw material monomer of the carboxy group-containing resin (b).

[0099] [Preparation of the Second Mixed Solution] As shown in Table 1, 59.8 parts by mass of 3,4-epoxycyclohexylmethyl methacrylate, which is an alicyclic epoxy group-containing ethylenically unsaturated compound (c), 0.6 parts by mass of tris(4-methylphenyl)phosphine (TPTP) as a catalyst, 100.0 parts by mass of n-butyl acetate as a solvent, and 91.1 parts by mass of toluene were contained in a second mixed solution prepared with respect to 100 parts by mass in total of the carboxyl group-containing resin (b) and the alicyclic epoxy group-containing ethylenically unsaturated monomer (c).

[0100] 175.6 parts by mass of n-butyl acetate as a solvent was charged into a four-necked flask equipped with a stirrer, a dropping funnel, a condenser tube, and a nitrogen inlet tube, and the temperature was raised to 80°C under a nitrogen gas atmosphere. While maintaining the reaction temperature at 80°C ± 2°C, the first mixed solution was uniformly dropped into the four-necked flask over 4 hours. After completion of the dropping, stirring was continued at a temperature of 80°C ± 2°C for another 6 hours to polymerize the carboxyl group-containing resin (b). Thereafter, 0.15 parts by mass of 4-methoxyphenol as a polymerization inhibitor was added to the reaction system with respect to 100 parts by mass in total of the carboxyl group-containing resin (b) and the alicyclic epoxy group-containing ethylenically unsaturated monomer (c).

[0101] The reaction system to which 4-methoxyphenol was added was heated to 100°C, the second mixed solution was dropped over 0.5 hours, and then stirring was continued at a temperature of 100°C for 8 hours to synthesize resin (A-1), which was then cooled to room temperature (23°C). As a result of identifying resin (A-1) by nuclear magnetic resonance method (NMR method), it was a compound represented by general formula (2-1). The repeating unit k in formula (1-1) in the compound represented by general formula (2-1) is 5 two different repeating units (k-1, k-2) of R

[0102]

Chemical formula

[0103] Regarding the resin (A-1), the weight-average molecular weight and the glass transition temperature were examined by the method shown below. Also, the acid value of the resin (A-1) was measured according to JIS K0070. The results are shown in Table 3.

[0104] <Weight-average molecular weight (Mw)> Using gel permeation chromatography (manufactured by Showa Denko K.K., SHODEX (registered trademark) GPC-101), measurement was carried out at room temperature under the following conditions and calculated in terms of polystyrene conversion. Column: Manufactured by Showa Denko K.K., SHODEX (registered trademark) LF-804 Column temperature: 40 °C Sample: 0.2 mass% tetrahydrofuran solution of resin (A) Flow rate: 1 ml / min Eluent: Tetrahydrofuran Detector: RI detector

[0105] <Glass transition temperature (Tg)> A 10 mg sample was taken from 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 heating rate of 10 °C / min, and the endothermic start temperature due to the observed glass transition was defined as Tg. When two Tgs were observed, the simple average value of the two Tgs was taken.

[0106] (Production Examples 2 to 8, 10 to 12) A first mixed solution was prepared in the same manner as in Production Example 1, except that the carboxy group-containing ethylenically unsaturated monomer (a), the ethylenically unsaturated monomer (d), and a polymerization initiator were used in the contents (parts by mass) shown in Tables 1 and 2. Also, a second mixed solution was prepared in the same manner as in Production Example 1, except that the alicyclic epoxy group-containing ethylenically unsaturated compound (c) (glycidyl methacrylate (GMA) in Production Example 8) and a catalyst were used in the contents (parts by mass) shown in Tables 1 and 2.

[0107] Resins (A-2) to (A-8) and (A-10) to (A-12) were obtained in the same manner as in Production Example 1, except that the above-mentioned first mixed solution and the above-mentioned second mixed solution were used. As a result of identifying resins (A-2) to (A-8) and (A-10) to (A-12) in the same manner as in Production Example 1, they were found to be compounds represented by General Formulas (2-2) to (2-8) and (2-10) to (2-12). In the compounds represented by General Formulas (2-2) to (2-8) and (2-10), the repeating unit k in Formula (1-1) is R 5 or 1 both R 5 and R

[0108] 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 above 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).

[0109]

Chemical Formula

[0110]

Chemical formula

[0111]

Chemical formula

[0112]

Chemical formula

[0113]

Chemical formula

[0114] For Resins (A-2) to (A-8) and (A-10) to (A-12), the weight-average molecular weight, glass transition temperature, and acid value were examined in the same manner as for photosensitive resin (A-1). The results are shown in Table 3.

[0115] (Production Example 9) A first mixed solution was prepared in the same manner as in Production Example 1, except that a carboxyl group-containing ethylenically unsaturated monomer (a), an ethylenically unsaturated monomer (d), and a polymerization initiator were used in the contents (parts by mass) shown in Table 2.

[0116] 261.7 parts by mass of ethyl acetate as a solvent was charged into a four-necked flask equipped with a stirrer, a dropping funnel, a condenser tube, and a nitrogen inlet tube, and heating under reflux was carried out. After heating under reflux, the first mixed solution described in Table 2 was uniformly dropped over 4 hours. After dropping, stirring was continued by heating under reflux for 6 hours. Thereafter, the reaction system was cooled to 60°C, and 286.4 parts by mass of ethyl acetate as a solvent, 0.15 part by mass of 4-methoxyphenol as a polymerization inhibitor with respect to a total of 100 parts by mass of the carboxyl group-containing resin (b) and 2-isocyanatoethyl methacrylate (MOI) described below, and 0.3 part by mass of dioctyltin dilaurate as a catalyst with respect to a total of 100 parts by mass of the carboxyl group-containing resin (b) and 2-isocyanatoethyl methacrylate (MOI) described below were added.

[0117] After 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 resin (A-9), which was then cooled to room temperature (23°C). As a result of identifying resin (A-9) in the same manner as in Production Example 1, it was a compound represented by General Formula (2-9). The repeating unit k in Formula (1-1) in the compound represented by General Formula (2-9) is R5 They are two different repeating units (k-1, k-2).

[0118]

Chemical formula

[0119] For resin (A-9), in the same manner as resin (A-1), the weight-average molecular weight, glass transition temperature, and acid value were examined. The results are shown in Table 3. Also, for resins (A-1) to (A-12), the numerical values of k-1, k-2, k (the sum of k-1 and k-2), l, m, n, n′, and n′′ in Chemical Formulas (2-1) to (2-12) are shown in Table 3.

[0120]

Table 1

[0121]

Table 2

[0122]

Table 3

[0123] Table 1 and Table 2 show the carboxy group-containing ethylenically unsaturated monomer (a) used in the production of resins (A-1) to (A-12), the ethylenically unsaturated monomer (d) copolymerizable with the above (a), the polymerization initiator, the alicyclic epoxy group-containing ethylenically unsaturated compound (c), the catalyst, the types and amounts used (parts by mass) of the polymerization inhibitor and the solvent, and the amounts used (parts by mass) of glycidyl methacrylate (GMA) and 2-isocyanatoethyl methacrylate (MOI), respectively.

[0124] "Examples 1 to 12, Comparative Examples 1 to 2" Ethyl acetate, which is a solvent, was added to the reaction solutions of the resins (A-1) to (A-12) synthesized in Production Examples 1 to 12, and the content of each of the resins (A-1) to (A-12) was adjusted to 30% by mass. Using the resin (A-1) to (A-12) solutions in which the content of the resins (A-1) to (A-12) was 30% by mass, an adhesive composition was obtained by the method shown below.

[0125] In a plastic container in a room shielded from actinic rays, 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, and stirred to obtain the 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 amounts (parts by mass) of the resin (A-1) to (A-12) solutions in which the content of the resins (A-1) to (A-12) is 30% by mass used. The numerical value of the photopolymerization initiator (B) is the amount (parts by mass) of the photopolymerization initiator (B) used 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) used with respect to 100 parts by mass of the resin (A).

[0126] [Table 4]

[0127] [Table 5]

[0128] [Table 6]

[0129] "TETRAD-C", "HX", and "TPO" in Tables 4 to 6, and "TETRAD-X" in Tables 4 and 5 are as shown below. "TETRAD-C" 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name: TETRAD-C) "TETRAD-X" N,N'-[1,3-Phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine] (manufactured by Mitsubishi Gas Chemical Company, Inc., trade name: TETRAD-X) "HX" Isocyanurate of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name: Coronate (registered trademark) HX) "TPO" 2,4,6-Trimethylbenzoyldiphenylphosphine oxide (manufactured by BASF, trade name: L-TPO)

[0130] "Manufacture of Adhesive Sheet" The adhesive compositions of Examples 1 to 12 and Comparative Examples 1 to 2 were directly applied onto a substrate so that the film thickness after drying would be 20 μm, and heat-dried at 100 °C for 2 minutes to form an adhesive layer. Then, a release sheet was laminated onto the adhesive layer to obtain the adhesive sheets of Examples 1 to 12 and Comparative Examples 1 to 2. As the substrate and the release sheet, a 50-μm thick polyethylene terephthalate (PET) film was used.

[0131] For the adhesive sheets of Examples 1 to 12 and Comparative Examples 1 to 2 thus obtained, the following items were evaluated by the following methods. The results are shown in Tables 4 to 6.

[0132] "Peel Strength before UV Irradiation" The adhesive sheet was cut into a size of 25 mm in length and 100 mm in width, and the release sheet was peeled off to expose the adhesive layer. Next, the adhesive sheet was attached to a glass plate such that the exposed adhesive layer (measurement surface) was in contact with the glass plate, and a 2-kg rubber roller (width: about 50 mm) was reciprocated once to obtain a sample for measuring the peel strength before UV irradiation. The obtained measurement sample was left standing for 24 hours in an environment of 23 °C and 50% humidity. Then, in accordance with JIS Z0237, a tensile test in the 180° direction was performed at a peel rate of 300 mm / min to measure the peel strength (N / 25 mm) of the adhesive sheet with respect to the glass plate.

[0133] "Peel Strength after UV Irradiation" Samples identical to those for measuring the peel strength before UV irradiation were prepared, and ultraviolet rays (UV) were irradiated from the surface on the adhesive sheet side under the condition of an irradiation dose of 500 mJ / cm 2 to obtain samples for measuring the peel strength after UV irradiation. For the UV irradiation, a conveyor-type ultraviolet irradiation device (manufactured by Eye Graphics Co., Ltd., 2KW lamp, 80W / cm) was used. For the obtained samples for measurement, the peel strength (N / 25 mm) of the adhesive sheet with respect to the glass plate was measured in the same manner as the "peel strength before UV irradiation".

[0134] "Peel strength after heat-resistant UV irradiation" Samples identical to those for measuring the peel strength before UV irradiation were prepared, heat-treated at 200 °C for 2 hours, cooled to room temperature (23 °C), and then irradiated with UV under the same conditions as the "peel strength after UV irradiation" to obtain samples for measuring the peel strength after heat-resistant UV irradiation. For the obtained samples for measurement, the peel strength (N / 25 mm) of the adhesive sheet with respect to the glass plate was measured in the same manner as the "peel strength after UV irradiation".

[0135] "Adhesive residue" The glass plate after measuring the peel strength after UV irradiation was visually observed and evaluated according to the following criteria. The results are shown in Tables 4 to 6. (Evaluation criteria) ○: No adhesive remains on the glass plate. △: Adhesive remains on a part of the glass plate. ×: Adhesive remains on the entire surface of the glass plate.

[0136] As shown in Tables 4 and 5, for the adhesive sheets of Examples 1 to 12, the "peel strength before UV irradiation" was 1.0 N / 25 mm or more, the "peel strength after heat-resistant UV irradiation" was less than 2.5 N / 25 mm, and the evaluation of adhesive residue was ○ or △. On the other hand, as shown in Table 6, for the adhesive sheets of Comparative Example 1 and Comparative Example 2 in which resin (A) does not contain a structure derived from an alicyclic compound, although the "peel strength after UV irradiation" was sufficiently low, the "peel strength after heat-resistant UV irradiation" was high, and the evaluation of adhesive residue was ×.

Claims

1. A dicing tape having a sheet-like base material and an adhesive layer formed on one side of the base material, wherein the adhesive layer contains 100 parts by mass of a resin (A) represented by the following general formula (1-1), 0.1 to 5.0 parts by mass of a photoinitiator (B), and 0.05 to 10 parts by mass of a crosslinking agent (C). 【Chemical 1】 【Chemical 2】 (In formula (1-1), k, l, m, and n represent the molar composition ratios 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 from 65 to 95. n is from 5 to 35. R １ ~R ４ is -H or -CH ３ is. R ５ is an alkyl group having 1 to 16 carbon atoms. 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 (j in the formula is 1 or 2). R ８ is the above general formula (1-2) or (1-3). In formulas (1-2) and (1-3), p and q are each 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 is.)

2. The dicing tape according to claim 1, wherein the weight average molecular weight of the resin (A) is 200,000 to 1,000,000.

3. The dicing tape according to claim 1 or claim 2, wherein n in the formula (1-1) is 10 to 33.

4. The dicing tape according to claim 1 or claim 2, wherein k in the formula (1-1) is 45 to 90, l is 4 to 40, and m is 1 to 15.

5. The dicing tape according to claim 1 or claim 2, wherein the glass transition temperature of the resin (A) is -80 to 0°C.

6. The resin (A) is an addition reaction product of a carboxyl group-containing resin (b) and an alicyclic epoxy group-containing ethylenically unsaturated compound (c), and the carboxyl group-containing resin (b) is a polymer of an ethylenically unsaturated monomer containing a carboxyl group-containing ethylenically unsaturated monomer (a). The dicing tape according to claim 1 or claim 2.

7. The dicing tape according to claim 6, wherein the carboxyl group-containing ethylenically unsaturated monomer (a) is at least one selected from (meth)acrylic acid and β-carboxyethyl (meth)acrylate.

8. The carboxyl group-containing resin (b) is a copolymer of a raw material monomer containing at least the carboxyl group-containing ethylenically unsaturated monomer (a) and an ethylenically unsaturated monomer (d) copolymerizable with the carboxyl group-containing ethylenically unsaturated monomer (a). The dicing tape according to claim 6 or claim 7.

9. The dicing tape according to claim 8, wherein the ethylenically unsaturated monomer (d) is at least one selected from isobornyl (meth)acrylate and benzyl (meth)acrylate.

10. The dicing tape according to claim 6 or claim 7, wherein the alicyclic epoxy group-containing ethylenically unsaturated compound (c) is 3,4-epoxycyclohexylmethyl methacrylate.

11. The dicing tape according to claim 1 or claim 2, characterized in that the peel strength after UV irradiation is 5% or less of the peel strength before UV irradiation.

12. The dicing tape according to claim 1 or claim 2, characterized in that the peel strength after UV irradiation after heating at 200°C is 15% or less of the peel strength before UV irradiation.

Images