Adhesive composition and adhesive member

Abstract

This crosslinkable (meth)acrylic polymer has: a structural unit (A) derived from a (meth)acrylic acid alkyl ester compound; a structural unit (B) derived from a compound having an acidic functional group; and a structural unit (C) derived from a photobase generator which is decomposed due to light irradiation, and generates a base as well as a gas. With respect to the total amount of structural units in the crosslinkable (meth)acrylic polymer, the content of the structural unit (A) is at least 60.0 mass%, the content of the structural unit (B) is at least 1.0 mass%, the content of the structural unit (C) is at least 6.0 mass%, and the total content of (A), (B), and (C) is at most 100 mass%.

Description

[Technical Field]

[0001] The present invention relates to a crosslinkable (meth)acrylic polymer, a pressure-sensitive adhesive composition, and a pressure-sensitive adhesive member. [Background technology]

[0002] BACKGROUND ART Pressure-sensitive adhesive tapes are widely used in the manufacturing processes of electronic components, semiconductor components, and the like for purposes such as temporary fixing of members or components, fixing during transportation, reinforcement, protection, and masking.

[0003] For example, in the manufacturing process of semiconductor chips, when the backside of a wafer is ground to a predetermined thickness, adhesive tape is attached to the front side of the wafer to protect the front side of the wafer. After the wafer is diced into individual chips, it is transferred to the mounting process. During this process, the wafer undergoes dicing, cleaning, drying, expanding, picking up, mounting, and other processes with the backside still attached to the adhesive tape.

[0004] The adhesive composition used in such adhesive tapes is required to have high enough adhesiveness to firmly fix adherends such as wafers and semiconductor chips during the processing step, and to be able to be peeled off without damaging the adherend after the processing step is completed.

[0005] As an adhesive composition that achieves such properties, Patent Document 1 discloses an easily dismantlable acrylic adhesive that contains a copolymer of a (meth)acrylic monomer having a tertiary alkoxycarbonyloxy group at its terminal and a vinyl monomer that does not have a tertiary alkoxycarbonyloxy group at its terminal, and that can separate components by heating at 200°C or higher for 10 minutes or more to decompose the tertiary alkoxycarbonyloxy group.

[0006] Patent Document 2 discloses a heat-peelable pressure-sensitive adhesive sheet having a substrate and a heat-expandable pressure-sensitive adhesive layer containing heat-expandable microspheres. The heat-peelable pressure-sensitive adhesive sheet is said to be easily peelable from an adherend by foaming or expanding a foaming agent or the like by heating during peeling.

[0007] Furthermore, Patent Document 3 discloses a pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive containing a polymer bonded with a polyfunctional monomer or oligomer having a radiation-polymerizable functional group. The pressure-sensitive adhesive sheet is said to be easily peelable from an adherend by irradiating the sheet with ultraviolet light to cure the polymer during peeling.

[0008] Patent Document 4 discloses an adhesive tape used in a process for processing a semiconductor wafer in a state where the semiconductor wafer is bonded to a support plate, the adhesive tape comprising a substrate and an adhesive layer made of an adhesive composition containing a specific tetrazole compound. The adhesive tape is said to be easily peeled from an adherend by irradiating the tape with light during peeling to generate gas from the tetrazole compound. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2019-210405 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-131507 [Patent Document 3] Japanese Patent Application Publication No. 5-32946 [Patent Document 4] Japanese Patent Application Laid-Open No. 2003-231872 Summary of the Invention [Problem to be solved by the invention]

[0010] Incidentally, semiconductor chips used in MEMS and the like are susceptible to heat damage, and therefore it is desirable that adhesive tapes used in the manufacturing process of semiconductor chips be peelable at low temperatures, for example, below 100°C. Furthermore, thin glass films and semiconductor chips with a thickness of about 50 μm are easily damaged when adhesive tape is peeled off, and therefore it is desirable that adhesive tapes used to temporarily fix these materials be peelable without leaving any adhesive residue, even with a low peeling force.

[0011] However, the adhesive of Patent Document 1 and the adhesive sheet of Patent Document 2 require heating to high temperatures when peeling. Furthermore, the adhesive sheet of Patent Document 3 shrinks significantly when cured, requiring a high peeling force when peeling, which could damage thin adherends. Furthermore, the adhesive tape of Patent Document 4 contains low-molecular-weight components such as tetrazole compounds, which can easily bleed out and contaminate the adherend. Thus, there is a problem in that the adherend is susceptible to damage, breakage, and contamination caused by heat when peeling.

[0012] The present invention has been made in view of the above circumstances, and aims to provide a crosslinkable (meth)acrylic polymer, an adhesive composition, and an adhesive member that have good adhesive properties and can be easily peeled even at low temperatures while reducing damage to an adherend. [Means for solving the problem]

[0013] [1] A crosslinkable (meth)acrylic polymer having a structural unit (A) derived from a (meth)acrylic acid alkyl ester compound, a structural unit (B) derived from a compound having an acidic functional group, and a structural unit (C) derived from a photobase generator that decomposes upon light irradiation to produce a base and generate a gas, wherein the content of the structural unit (A) is 60.0% by mass or more, the content of the structural unit (B) is 1.0% by mass or more, and the content of the structural unit (C) is 6.0% by mass or more, relative to the total amount of structural units in the crosslinkable (meth)acrylic polymer, and the total content of the structural units (A), (B) and (C) is 100% by mass or less. [2] A crosslinkable (meth)acrylic polymer having a structural unit (A) derived from a (meth)acrylic acid alkyl ester compound, a structural unit (B) derived from a compound having an acidic functional group, and a structural unit (C) derived from a photobase generator that is decomposed by light irradiation to generate a base and generate a gas, wherein the thickness of the crosslinkable (meth)acrylic polymer is adjusted to be in the range of 1 to 45 μm, and a cumulative irradiation dose of 7488 mJ / cm is applied to a layer made of the crosslinkable (meth)acrylic polymer. 2 A crosslinkable (meth)acrylic polymer that exhibits a mass loss rate of 1.0% or more when irradiated with ultraviolet light, as expressed by the following formula: Mass reduction rate (%) = mass difference (g) of the layer before and after irradiation / mass (g) of the layer before irradiation × 100 [3] The crosslinkable (meth)acrylic polymer according to [1] or [2], wherein the photobase generator contains a group derived from an oxime ester or a carbamate. [4] The crosslinkable (meth)acrylic polymer according to any one of [1] to [3], wherein the structural unit (C) is derived from a compound represented by the following formula: [ka] (In formula (2-1), X 1 and X 2 are independently —O— or —NH—, R 1 is H or a methyl group, R 12 is H or a substituted or unsubstituted C1-C4 alkyl group, R 13 is a substituted or unsubstituted polyvalent alkyl group, a substituted or unsubstituted cycloalkylene group, or a substituted or unsubstituted arylene group, and R 12 and R 13 may be bonded to each other to form a ring, R 14 is a substituted or unsubstituted alkylene group, R 15 is a nitro group or an alkoxy group, n is an integer from 0 to 2, y is an integer from 1 to 3. [5] The crosslinkable (meth)acrylic polymer according to any one of [1] to [4], wherein the ratio (B+C) / A of the total content of the structural unit (B) and the structural unit (C) to the content of the structural unit (A) is 10 / 90 to 30 / 70 (mass ratio). [6] The crosslinkable (meth)acrylic polymer according to any one of [1] to [5], wherein the content ratio C / B of the structural unit (B) to the structural unit (C) is 0.4 to 2.5 (molar ratio). [7] The crosslinkable (meth)acrylic polymer according to any one of [1] to [6], wherein the alkyl chain of the (meth)acrylic acid alkyl ester compound has 2 to 20 carbon atoms. [8] The crosslinkable (meth)acrylic polymer according to any one of [1] to [7], which has a weight average molecular weight of 200,000 or more. [9] The crosslinkable (meth)acrylic polymer according to any one of [1] to [8], which has a polydispersity (Mw / Mn) of 2.0 to 8.0.

[0014]

[10] A pressure-sensitive adhesive composition comprising the crosslinkable (meth)acrylic polymer according to any one of [1] to [9] and a crosslinking agent.

[11] The pressure-sensitive adhesive composition according to

[10] , wherein the content of the crosslinking agent is 0.00 to 2.00 parts by mass per 100 parts by mass of the crosslinkable (meth)acrylic polymer.

[0015]

[12] An adhesive member having an adhesive layer containing the adhesive composition according to

[10] or

[11] .

[0016]

[13] An adhesive composition comprising a polymer α having a structural unit (A) derived from a (meth)acrylic acid alkyl ester compound and a polymer β having a structural unit (B) derived from a compound having an acidic functional group, wherein at least one of the polymer α and the polymer β further comprises a structural unit (C) derived from a photobase generator that decomposes upon light irradiation to generate a base and generate a gas, and the content of the structural unit (A) is 60.0 mass% or more, the content of the structural unit (B) is 1.0 mass% or more, and the content of the structural unit (C) is 6.0 mass% or more, and the total content of the structural units (A), (B) and (C) is 100 mass% or less, relative to the total amount of the structural units of the polymer α and the polymer β.

[14] A pressure-sensitive adhesive composition comprising a polymer α having a structural unit (A) derived from a (meth)acrylic acid alkyl ester compound and a polymer β having a structural unit (B) derived from a compound having an acidic functional group, at least one of the polymer α and the polymer β further contains a structural unit (C) derived from a photobase generator that is decomposed by light irradiation to generate a base and generate a gas; The thickness of the pressure-sensitive adhesive composition molded article was adjusted to be in the range of 1 to 45 μm, and the cumulative irradiation dose was 7488 mJ / cm 2 When irradiated with ultraviolet light, the mass loss rate of the molded body, as represented by the following formula, is 1.0% or more. Adhesive composition. Mass reduction rate (%) = mass difference (g) of the molded body before and after irradiation / mass (g) of the molded body before irradiation × 100 [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a crosslinkable (meth)acrylic polymer, an adhesive composition, and an adhesive member that have good adhesive properties and can be easily peeled even at low temperatures while reducing damage to an adherend. [Brief explanation of the drawings]

[0018] [Figure 1]FIG. 1 is a graph showing the peel strength before and after light irradiation when the total ratio of the structural unit (B) and the structural unit (C), (B+C) / A, is changed. [Figure 2] 2A and 2B are schematic cross-sectional views showing examples of use of the adhesive member. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present inventors have found that by containing, in one polymer or in a combination of multiple polymers, a structural unit (A) derived from a (meth)acrylic acid alkyl ester compound, a structural unit (B) derived from a compound having an acidic functional group, and a structural unit (C) derived from a photobase generator that generates a base and a gas upon irradiation with light, and by setting the content of the structural unit (C) to a predetermined level or more, a sufficient adhesive strength is exerted during use while high releasability is exhibited during peeling.

[0020] The following is a presumed scheme for peeling in an example of a crosslinkable (meth)acrylic polymer. [ka]

[0021] As described above, upon irradiation with light, the protecting group in the structural unit (C) is eliminated, generating a base (e.g., an amine) and a by-product gas (e.g., carbon dioxide). The gas generation reduces the adhesive area at the interface between the adhesive composition containing the polymer and the adherend (interfacial breakdown). Furthermore, the base generated from the structural unit (C) of one polymer molecule and the acidic functional group possessed by the structural unit (B) of the other polymer molecule undergo an acid-base reaction to form an ionic crosslink, thereby increasing the elastic modulus of the adhesive composition containing the polymer (viscoelastic change). These two actions facilitate peeling without heating. Furthermore, the ionic crosslinking increases the elastic modulus of the adhesive composition, thereby suppressing re-adhesion after peeling. The structure of the crosslinkable (meth)acrylic polymer of the present invention will be described in detail below.

[0022] 1. Crosslinkable (meth)acrylic polymer A crosslinkable (meth)acrylic polymer according to one embodiment of the present invention comprises a structural unit (A) derived from a (meth)acrylic acid alkyl ester compound, a structural unit (B) derived from a compound having an acidic functional group, and a structural unit (C) derived from a photobase generator. In this specification, "(meth)acrylic" refers to acrylic, methacrylic, or both.

[0023] The crosslinkable (meth)acrylic polymer contains 60.0% by mass or more of the structural unit (A), 1.0% by mass or more of the structural unit (B), and 6.0% by mass or more of the structural unit (C), with the proviso that the total content of the structural units (A), (B), and (C) is 100% by mass or less.

[0024] Thus, when the content of the structural unit (C) is 6.0% by mass or more, upon irradiation with light, the protecting group is eliminated from the structural unit (C), generating a sufficient amount of base and a sufficient amount of gas. The gas generation can reduce the contact area between the adhesive composition containing the polymer and the adherend. Furthermore, the base generated from the structural unit (C) forms an ionic crosslink with the acidic functional group of the structural unit (B), thereby increasing the elastic modulus of the adhesive composition. As a result, the adhesive composition can be easily peeled off without heating to a high temperature.

[0025] From the same viewpoint, the content of the structural unit (A) is preferably 60.0 to 93.0 mass%, more preferably 70.0 to 90.0 mass%, based on the total amount of structural units in the crosslinkable (meth)acrylic polymer. When the content of the structural unit (A) is equal to or greater than the lower limit, the adhesiveness of the pressure-sensitive adhesive composition is likely to be further increased, and when it is equal to or less than the upper limit, the releasability during peeling is less likely to be impaired.

[0026] The content of the structural unit (B) is preferably 1.0 to 15.0 mass%, more preferably 1.5 to 10.0 mass%, based on the total amount of structural units in the crosslinkable (meth)acrylic polymer. When the content of the structural unit (B) is equal to or greater than the lower limit, ionic crosslinking between the base generated from the structural unit (C) upon light irradiation and the acidic functional group of the structural unit (B) is more likely to be formed, and the elastic modulus of the pressure-sensitive adhesive composition is more likely to be increased. As a result, the releasability is more likely to be improved. When the content of the structural unit (B) is equal to or less than the upper limit, the adhesiveness is less likely to be impaired.

[0027] The content of the structural unit (C) is preferably 6.0 to 30.0 mass%, more preferably 8.0 to 25.0 mass%, and even more preferably more than 15.0 mass% but not more than 25.0 mass%, based on the total amount of structural units in the crosslinkable (meth)acrylic polymer. When the content of the structural unit (C) is equal to or greater than the lower limit, more gas and base are likely to be generated from the structural unit (C) upon light irradiation. This further reduces the contact area between the pressure-sensitive adhesive composition and the adherend, and the elastic modulus is further increased by ionic crosslinking, making it easier to further improve releasability. When the content of the structural unit (C) is equal to or less than the upper limit, adhesiveness is less likely to be impaired.

[0028] The ratio (B+C) / A (mass ratio) of the total content of the structural units (B) and (C) to the content of the structural unit (A) (hereinafter also referred to as the "total ratio of the structural units (B) and (C)") is not particularly limited, but from the viewpoint of the balance between adhesiveness and releasability, it is preferably 8 / 92 to 40 / 60, and more preferably 10 / 90 to 30 / 70. When (B+C) / A is equal to or greater than the lower limit, adhesiveness before light irradiation can be improved while releasability after light irradiation can also be improved. When (B+C) / A is equal to or less than the upper limit, adhesiveness is less likely to be impaired. This is also shown below.

[0029] FIG. 1 is a graph showing the peel strength before and after light irradiation when the total ratio of the structural unit (B) and the structural unit (C), (B+C) / A, is changed.

[0030] Generally, the peel strength of a pressure-sensitive adhesive composition increases with increasing modulus of elasticity until the modulus reaches a certain level; after that, the peel strength decreases with increasing modulus of elasticity. Here, increasing the total ratio (B+C) / A of the structural units (B) and (C) tends to increase the modulus of elasticity and the peel strength before light irradiation due to hydrogen bonding and other factors. On the other hand, after light irradiation, the modulus of elasticity tends to increase due to acid-base reactions (ionic crosslinking), and the peel strength tends to decrease. In other words, increasing the total ratio (B+C) / A results in good adhesiveness before light irradiation and good releasability after light irradiation (see Figure 1).

[0031] The content ratio C / B (molar ratio) of the structural unit (B) to the structural unit (C) is not particularly limited, but from the viewpoint of a balance between adhesiveness and releasability, it is preferably 0.3 to 3, and more preferably 0.4 to 2.5. When C / B is equal to or greater than the lower limit, the ratio of the amount of base generated from the structural unit (C) to the amount of acidic functional group derived from the structural unit (B) is more balanced, making it easier to increase the elastic modulus by ionic crosslinking. When C / B is equal to or less than the upper limit, the polarity is not too high, so that releasability after light irradiation is less likely to be impaired.

[0032] The monomer composition of the crosslinkable (meth)acrylic polymer (the content of the structural units (A), (B), and (C)) can be determined by pyrolysis GC / MS and NMR. For example, the type of monomer can be determined by pyrolysis GC / MS, 1 The ratio of the monomers can be determined from the integral value of the peak corresponding to each monomer in H-NMR.

[0033] Each structural unit will be explained below.

[0034] Structural unit (A) The structural unit (A) is derived from a (meth)acrylic acid alkyl ester compound and has the function of adjusting the Tg of the polymer and imparting adhesiveness, for example.

[0035] From the viewpoint of exhibiting amorphous properties and easily increasing adhesiveness, the (meth)acrylic acid alkyl ester compound is preferably a (meth)acrylic acid alkyl ester compound having an alkyl chain containing 2 to 20 carbon atoms. The alkyl chain containing 2 to 20 carbon atoms may be a linear alkyl chain containing 2 to 20 carbon atoms, preferably 2 to 9 carbon atoms, and more preferably 2 to 7 carbon atoms, or may be a branched alkyl chain containing 3 to 20 carbon atoms, preferably 3 to 10 carbon atoms. As the number of carbon atoms in the alkyl chain increases appropriately, the Tg of the polymer tends to decrease, and adhesiveness tends to be increased.

[0036] Examples of (meth)acrylic acid alkyl ester compounds having a linear alkyl chain include ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, and n-nonyl (meth)acrylate. Examples of acrylic acid alkyl ester compounds having a branched alkyl chain include isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Among these, the (meth)acrylic acid alkyl ester compound is preferably an acrylic acid alkyl ester compound.

[0037] Structural unit (B) The structural unit (B) is derived from a compound having an acidic functional group. When the structural unit (B) is irradiated with light, the acidic functional group reacts with the base generated from the structural unit (C) upon irradiation to form an ionic crosslink.

[0038] The compound having an acidic functional group may be an ethylenically unsaturated compound having an acidic functional group. Examples of the acidic functional group include a carboxylic acid group (carboxyl group), a phenolic hydroxyl group, a boronic acid group, a sulfonic acid group, a phosphoric acid group, or a salt thereof.

[0039] Examples of ethylenically unsaturated compounds having a carboxylic acid group include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and 2-acryloyloxyethyl succinic acid. The carboxyl group may be dissociated or may form a complex salt. When forming a complex salt, it may form a complex salt with an alkali metal.

[0040] Examples of the ethylenically unsaturated compound having a phenolic hydroxyl group include ethylenically unsaturated carboxylic acid esters having a phenolic hydroxyl group, such as 4-hydroxyphenyl methacrylate, 4-vinylphenol, 4-isopropenylphenol, and N-(4-hydroxyphenyl)methacrylamide.

[0041] Examples of the ethylenically unsaturated compound having a boronic acid group include 4-methacrylamidophenylboronic acid.

[0042] Examples of ethylenically unsaturated compounds having a sulfonic acid group include allyl sulfonic acid, methallyl sulfonic acid, p-styrene sulfonic acid, 4-methallyloxybenzene sulfonic acid, 2-(methacryloyloxy)ethane sulfonic acid, vinyl sulfonic acid, vinylbenzene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and t-butylacrylamido sulfonic acid. The sulfonic acid group may be dissociated or may form a complex salt. When a complex salt is formed, it may form a complex salt with an alkali metal or ammonium ion.

[0043] Examples of ethylenically unsaturated compounds having a phosphoric acid group include vinylphosphonic acid and acid phosphoxy(meth)acrylate (e.g., 2-((meth)acryloyloxy)ethyl phosphate). The phosphoric acid group may be dissociated or may form a complex salt. When forming a complex salt, it may form a complex salt with an ammonium ion or alkanolamine residue having, for example, an alkyl group, an allyl group, an aralkyl group, or the like.

[0044] Among these, ethylenically unsaturated compounds having a carboxylic acid group are preferred, acrylic acid and methacrylic acid are more preferred, and acrylic acid is even more preferred. From the viewpoint of further increasing the elastic modulus of the polymer and thereby further improving the peelability after light irradiation, compounds having a rigid structure (e.g., aromatic ring) are preferred, and ethylenically unsaturated carboxylic acid esters having a phenolic hydroxyl group are more preferred.

[0045] Structural unit (C) The structural unit (C) is derived from a photobase generator. The structural unit (C) decomposes (cleaves bonds) upon irradiation with light to generate a base and also generates a by-product gas, thereby improving strippability.

[0046] The photobase generator is an ethylenically unsaturated compound that decomposes upon irradiation with light to generate a base and also generate a by-product gas. The ethylenically unsaturated compound is preferably a (meth)acrylic acid ester compound, more preferably an acrylic acid ester compound. The base generated by decomposition of the photobase generator is preferably a base that undergoes an acid-base reaction (ionically crosslinks) with the acidic functional group of the structural unit (B), more preferably an amine. The amine may be any of primary amine, secondary amine, and tertiary amine, but is preferably a secondary amine or tertiary amine from the viewpoint of basicity. The by-product gas generated by decomposition of the photobase generator is carbon dioxide gas, sulfur dioxide gas, nitrogen gas, NH3 gas, etc., and is preferably carbon dioxide gas.

[0047] Such a photobase generator may be a nonionic type or an ionic type. From the viewpoints of storage stability and heat resistance, a nonionic type photobase generator is preferred, and from the viewpoint of reactivity, an ionic type photobase generator is preferred.

[0048] (Non-ionic photobase generator) The non-ionic photobase generator preferably has a group derived from an oxime ester or a carbamate.

[0049] Examples of the ethylenically unsaturated compound having a group derived from an oxime ester include compounds represented by formula (1). [ka]

[0050] In formula (1), R 1 is H or a methyl group. R 2 and R 3 are each a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group. The substituted or unsubstituted alkyl group is preferably a substituted or unsubstituted C1 to C30 alkyl group. The substituted or unsubstituted aryl group is preferably a substituted or unsubstituted C6 to C30 aryl group.

[0051] Examples of compounds represented by formula (1) include the following: [ka]

[0052] Examples of the ethylenically unsaturated compound having a group derived from carbamate include compounds represented by formula (2).

[0053] [ka]

[0054] In formula (2), R 1 is the R in equation (1). 1 is synonymous with. X 1 is —O— or —NH—, preferably —O—. R 11 is —C(═O)—OR (R is an aromatic ring-containing alkyl group). R 12 is H or a substituted or unsubstituted C1 to C4 alkyl group. R 13is a substituted or unsubstituted polyvalent alkyl group, a substituted or unsubstituted cycloalkylene group, or a substituted or unsubstituted arylene group. The polyvalent alkyl group is preferably a divalent or trivalent substituted or unsubstituted C1 to C8 alkyl group, and the substituted or unsubstituted cycloalkylene group is preferably a substituted or unsubstituted cyclohexylene group. R 12 and R 13 may be bonded to each other to form a ring. 12 and R 13 The ring formed by bonding is preferably an aliphatic ring such as a cyclohexane ring. In other words, -R in equation (2) 13 NR 11 R 12 is a photolabile group that dissociates upon irradiation with light, specifically a group derived from a carbamate. Examples of carbamates include benzyl carbamate, benzoin carbamate, and carbamates having a coumarin structure.

[0055] Examples of benzyl carbamates include ortho-nitrobenzyl carbamates such as: 12 and R 13 are the R in equation (2), respectively. 12 and R 13 Corresponds to. [ka]

[0056] R 16 is H, methyl, methoxy, 2-nitrobenzyl or 2,6-dinitrobenzyl, R 17 and R 18 are H, a methoxy group, or a nitro group, R 16 and R 17 may be bonded to each other to form a ring (e.g., an ethylenedioxy ring), R 19 is H, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

[0057] Other examples of benzyl carbamates include (α,α-dimethyl-3,5-dimethoxybenzyloxy)carbonyl compounds such as: [ka]

[0058] Examples of benzoin carbamates include the following compounds: [ka]

[0059] R 20 is H, 4-methoxy group, -SMe, 3,5-methoxy group, 3,4-C4H4(2-Naphth); R 21 is H or a 3,5-methoxy group; R 22 is H or 3,5-DiOMePh.

[0060] Examples of carbamates having a coumarin structure include the following compounds: [ka]

[0061] Among these, the nonionic photobase generator is preferably a compound represented by formula (2). The carbamate-derived group in the compound represented by formula (2) is preferably a group derived from benzyl carbamate or benzoin carbamate, more preferably a group derived from benzyl carbamate. That is, the compound represented by formula (2) is particularly preferably a compound represented by formula (2-1). [ka]

[0062] X in formula (2-1) 1 , R 1 , R12 and R 13 is X in equation (2). 1 , R 1 , R 12 and R 13 are synonymous with each other. X 2 is —O— or —NH—, preferably —O—. R 14 is a substituted or unsubstituted alkylene group, R 15 is a nitro group or an alkoxy group, n is an integer from 0 to 2, y is an integer of 1 to 3, and is preferably 1.

[0063] The compound represented by formula (2) can be prepared, for example, by reacting an ethylenically unsaturated compound having a reactive isocyanate functional group (e.g., an isocyanatoalkyl(meth)acrylate) with a photolabile compound having a hydroxyl functional group (e.g., benzyl alcohol).

[0064] (Ionic photobase generator) The ionic photobase generator is, for example, a compound represented by the following general formula (3). [ka]

[0065] In formula (3), R 4 represents hydrogen, halogen, a hydroxyl group, a mercapto group, a sulfide group, a silyl group, a silanol group, a cyano group, a nitro group, a nitroso group, a sulfino group, a sulfo group, a sulfonato group, a phosphino group, a phosphinyl group, a phosphono group, a phosphonato group, an amino group, an alkoxy group, an amido group, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, an aryl group having 6 to 14 carbon atoms, an arylalkyl group having 7 to 15 carbon atoms, a saturated aliphatic ring, an unsaturated aliphatic ring, an aromatic ring, or an organic group. 4 When has a cyclic structure, it may contain a heteroatom.

[0066] In formula (3), HB+ represents a protonated base, and is a basic compound such as an amine, a compound containing a pyridyl group, a hydrazine compound, an amide compound, a quaternary ammonium hydroxide salt, a mercapto compound, a sulfide compound, or a phosphine compound. + is preferably a compound derived from aminoethylated acrylic acid, N-[3-(dimethylamino)propyl]acrylamide, 2,2,6,6-tetramethyl-4-piperidyl methacrylate or 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate that has been protonated.

[0067] Among them, the ionic photobase generator is preferably one obtained by reacting the above-mentioned base with an ionic additive such as ketoprofen, an N-acetoxyphthalimide derivative, or cyanoacrylic acid dithiophene. That is, the ionic photobase generator preferably has a group derived from ketoprofen, an N-acetoxyphthalimide derivative, or cyanoacrylic acid dithiophene. Specific examples of the ionic photobase generator include compounds having a structure represented by the following formula: In the following formula, HB + is the HB of Eq. (3). + is similar to R 23 is H or a nitro group. [ka]

[0068] A crosslinkable (meth)acrylic polymer having such a structural unit (C) can be obtained, for example, by reacting a (meth)acrylic polymer having a primary, secondary, or tertiary amine in a side chain with the above-mentioned ketoprofen, N-acetoxyphthalimide derivative, or cyanoacrylate dithiophene.

[0069] Other building blocks The crosslinkable (meth)acrylic polymer may further contain structural units other than those described above, if necessary. Examples of such structural units include acrylamide, hydroxyethyl acrylate, functional group-containing acrylates such as hydroxyethyl acrylate and 4-hydroxybutyl acrylate, styrenes, and (meth)acrylic acid alkyl esters other than those described above. However, the content of such structural units may be 15% by mass or less based on the total amount of structural units in the crosslinkable (meth)acrylic polymer.

[0070] Physical properties The weight-average molecular weight Mw of the crosslinkable (meth)acrylic polymer is not particularly limited, but is preferably high from the viewpoint of further enhancing releasability. Specifically, the Mw of the crosslinkable (meth)acrylic polymer is preferably 200,000 or more, and more preferably 300,000 to 1,200,000.

[0071] The dispersity (Mw / Mn) of the crosslinkable (meth)acrylic polymer is not particularly limited, but is preferably low from the viewpoint of further enhancing releasability. Specifically, the Mw / Mn of the crosslinkable (meth)acrylic polymer is preferably 2.0 to 8.0, more preferably 2.0 to 6.5, and even more preferably 2.5 to 6.0.

[0072] The Mw and Mw / Mn of the crosslinkable (meth)acrylic polymer can be measured in terms of standard polystyrene using gel permeation chromatography (GPC). The GPC analysis conditions are as follows: Automatic injection device: 717plus, manufactured by Japan Waters Pump: Nippon Waters 515 HPLC pump Column: Showa Denko PLgel 10μ MIXED-B, 7.5 x 300 mm (3 columns) Refractive index detector: Showa Denko, Shodex R-101 Column calibration: Agilent Technologies, EasiCal PS-1 polystyrene Eluent: tetrahydrofuran for HPLC, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Column temperature: 40℃ Flow rate: 1.0ml / min

[0073] The glass transition temperature Tg of the crosslinkable (meth)acrylic polymer is not particularly limited, but is preferably low from the viewpoint of obtaining sufficient adhesiveness, and can be, for example, −80° C. to 10° C. The Tg of the crosslinkable (meth)acrylic polymer can be determined by measuring the viscoelasticity in a shear mode at a temperature range of −70° C. to 150° C. and a heating rate of 5° C. / min using a viscoelasticity tester while applying a shear strain at a frequency of 1 Hz, and the peak top temperature of tan δ (loss tangent) can be taken as the Tg of the homopolymer.

[0074] A cumulative irradiation dose of 7488 mJ / cm was applied to a layer made of a crosslinkable (meth)acrylic polymer adjusted to a thickness within the range of 1 to 45 μm. 2 When irradiated with ultraviolet light, the mass loss rate of the layer, expressed by the following formula, is 1.0% or more, preferably 1.5% or more, more preferably 2.0% or more, and even more preferably 2.5% or more. The upper limit of the mass loss rate is not particularly limited, but can be, for example, less than 100%. Mass reduction rate (%) = mass difference of the above layer before and after irradiation (g) / mass of the above layer before irradiation (g) × 100

[0075] When the mass loss rate is within the above range, interfacial breakdown and the above-mentioned ionic crosslinking occur between the layer made of the crosslinkable (meth)acrylic polymer and the adherend, thereby achieving the effects of easy peeling without heating and suppressing re-adhesion after peeling. The mass loss rate can be controlled by the types and contents of the structural units (A) to (C).

[0076] About the synthesis method The crosslinkable (meth)acrylic polymer according to this embodiment can be obtained, for example, by polymerizing the monomers constituting the structural units (A), (B), and (C) in the presence of an initiator. The polymerization can be carried out in the presence of, or preferably in the absence of, a suitable solvent that does not react with the functional groups of the crosslinkable (meth)acrylic polymer, such as ethyl acetate, toluene, or tetrahydrofuran.

[0077] The initiator may be any radical initiator that does not photodecompose the photobase generator, and is preferably a thermal initiator. Examples of the thermal initiator include peroxides such as benzoyl peroxide, dibenzoyl peroxide, dilauryl peroxide, cyclohexane peroxide, methyl ethyl ketone peroxide, hydroperoxides, dicyclohexyl peroxydicarbonate, 2,2-azo-bis(isobutyronitrile), and 2,2'-azobis(2,4-dimethylvaleronitrile).

[0078] 2.Adhesive composition The adhesive composition according to one embodiment of the present invention may be a composition containing the above-mentioned crosslinkable (meth)acrylic polymer (first embodiment); or may be a composition containing a polymer α containing some of the above-mentioned structural units (A), (B), and (C), and a polymer β containing the remainder (second embodiment).

[0079] 2-1.Polymers When the adhesive composition contains polymer α and polymer β, it preferably contains, for example, polymer α containing structural unit (A) and polymer β containing structural unit (B), at least one of which further contains structural unit (C); it is more preferable that the adhesive composition contains polymer α containing structural unit (A) and structural unit (C) and polymer β containing structural unit (A) and structural unit (B).

[0080] In a pressure-sensitive adhesive composition containing polymer α and polymer β, the contents of the structural unit (A), the structural unit (B), and the structural unit (C) relative to the total amount of structural units of polymer α and polymer β can be the same as the contents of the structural unit (A), the structural unit (B), and the structural unit (C) relative to the total amount of structural units of the crosslinkable (meth)acrylic polymer. The contents of the structural unit (A), the structural unit (B), and the structural unit (C) relative to the total amount of structural units of polymer α and polymer β can be adjusted by the monomer composition of polymer α and polymer β and the amounts thereof blended in the composition.

[0081] Furthermore, the content ratio C / B (molar ratio) of the structural unit (B) to the structural unit (C) in the pressure-sensitive adhesive composition containing polymer α and polymer β can be the same as the content ratio (molar ratio) of the structural unit (B) to the structural unit (C) in the above-mentioned crosslinkable (meth)acrylic polymer. In addition, the ratio (B+C) / A (mass ratio) of the total content of the structural unit (B) and the structural unit (C) to the content of the structural unit (A) in the pressure-sensitive adhesive composition containing polymer α and polymer β can be the same as the total ratio (B+C) / A (mass ratio) of the structural unit (B) and the structural unit (C) in the above-mentioned acrylic polymer.

[0082] The content of the crosslinkable (meth)acrylic polymer or the total content of polymers α and β in the pressure-sensitive adhesive composition is not particularly limited as long as it exhibits the desired adhesiveness and releasability, but is, for example, 10 to 100 mass %, preferably 30 to 100 mass %, and more preferably 50 to 100 mass % relative to the non-volatile components of the pressure-sensitive adhesive composition.

[0083] 2-2.Other ingredients The pressure-sensitive adhesive composition according to one embodiment of the present invention may further contain other components in addition to those described above, as necessary. Examples of the other components include a crosslinking agent, an organic solvent, a tackifier, a plasticizer, an antioxidant, an ultraviolet absorber, an anti-aging agent, a flame retardant, an anti-fungal agent, a silane coupling agent, a filler, a colorant, etc., and preferably includes a crosslinking agent or an organic solvent.

[0084] (Crosslinking agent) The crosslinking agent has a function of pre-crosslinking the crosslinkable (meth)acrylic polymer or the polymers α and β, which can further increase the modulus of elasticity of the pressure-sensitive adhesive composition containing the polymer, thereby further increasing the adhesiveness before light irradiation and further improving the releasability after light irradiation.

[0085] The crosslinking agent may be any agent that reacts with the acidic functional group (preferably a carboxylic acid group) of the structural unit (B). Examples of such crosslinking agents include organometallic complexes and compounds having two or more crosslinkable groups selected from a glycidyl group, an isocyanate group, a carbodiimide group, an aziridinyl group, and an oxazolyl group. Among these, organometallic complexes, compounds having two or more glycidyl groups, and compounds having two or more isocyanate groups are preferred from the viewpoint of facilitating the crosslinking reaction.

[0086] Examples of organometallic complexes include titanium-based complexes, zirconium-based complexes, and aluminum-based complexes, with titanium-based complexes being preferred. Titanium-based complexes contain a Ti-O-C bond in each molecule, and the presence of this alkoxy group strengthens the inter- or intramolecular cross-linking of the resin. Examples of titanium-based complexes include titanium alkoxides and titanium acylates. Examples of titanium alkoxides include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, and tetramethyl titanate, as well as triethanolamine titanate, titanium acetylacetate, titanium ethylacetoacetate, titanium lactate, octylene glycol titanate, titanium tetraacetylacetate, and titanium phosphate compounds, with titanium acetylacetate being preferred.

[0087] Examples of compounds having two or more isocyanate groups include aliphatic isocyanates such as hexamethylene diisocyanate (HDI), alicyclic isocyanates such as isophorone diisocyanate, cyclohexyl diisocyanate, and hydrogenated xylene diisocyanate (XDI), and aromatic isocyanates such as diphenylmethane diisocyanate (MDI), tolylene diisocyanate, p-phenylene diisocyanate, and xylene diisocyanate (XDI). Among these, aliphatic isocyanates are preferably used as crosslinking agents.

[0088] Examples of compounds having two or more glycidyl groups include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, diglycidylamine, etc. Among these, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane is preferred from the viewpoint of reactivity with carboxyl groups.

[0089] The content of the crosslinking agent is preferably 0.00 to 2.00 parts by mass, more preferably 0.00 to 1.0 part by mass, and even more preferably 0.00 to 0.030 parts by mass, per 100 parts by mass of the content of the crosslinkable (meth)acrylic polymer or the total content of polymers α and β. When the content of the crosslinking agent is equal to or greater than the lower limit, the polymer can be appropriately crosslinked before light irradiation, which makes it easier to further increase the adhesive strength before light irradiation and to further improve the releasability after light irradiation. When the content of the crosslinking agent is equal to or less than the upper limit, the acidic functional groups of the structural unit (B) are not excessively consumed by reaction with the crosslinking agent, and therefore the formation of ionic crosslinks by light irradiation is less likely to be inhibited.

[0090] (organic solvent) The organic solvent may be a solvent used in synthesizing the polymer. Examples of the organic solvent include aromatic hydrocarbon solvents such as toluene and xylene, ester solvents such as methyl acetate, ethyl acetate, isopropyl acetate, normal propyl acetate and butyl acetate, and ether solvents such as tetrahydrofuran.

[0091] The adhesive composition may be in a liquid form or in a film form (for example, a film supported on a substrate).

[0092] 2-3.Physical properties A molded product of the adhesive composition (for example, an adhesive layer containing the adhesive composition) adjusted to a thickness within the range of 1 to 45 μm was exposed to an accumulated irradiation dose of 7488 mJ / cm 2 When irradiated with ultraviolet light, the mass loss rate of the molded product, expressed by the following formula, is 1.0% or more, preferably 1.5% or more, more preferably 2.0% or more, and even more preferably 2.5% or more. The upper limit of the mass loss rate is not particularly limited, but can be, for example, less than 100%. Mass reduction rate (%) = mass difference (g) of the molded body before and after irradiation / mass (g) of the molded body before irradiation × 100

[0093] When the mass loss rate of the molded body of the adhesive composition is within the above range, the above-mentioned interfacial breakdown and the above-mentioned ionic crosslinking occur between the adhesive composition and the adherend, resulting in the effects of easy peeling without heating and suppressing re-adhesion after peeling. As described above, the mass loss rate can be controlled by the content of the crosslinkable (meth)acrylic polymer in the pressure-sensitive adhesive composition and the types and contents of the structural units (A) to (C) in the crosslinkable (meth)acrylic polymer.

[0094] 3. Adhesive materials An adhesive member according to one embodiment of the present invention has an adhesive layer containing the adhesive composition. For example, the adhesive member may be an adhesive film containing a substrate and an adhesive layer containing the adhesive composition. Alternatively, the adhesive member may be an adhesive tape containing a substrate and an adhesive layer containing the adhesive composition. The adhesive film or adhesive tape may be used for semiconductor components.

[0095] Examples of the substrate include paper, film, cloth, nonwoven fabric, metal foil, etc. The film is preferably a resin film, and examples of its material include polyolefins such as polyethylene and polypropylene, polystyrene, polyester, polyvinyl alcohol, poly(ethylene terephthalate), poly(ethylene naphthalate), poly(butylene terephthalate), poly(caprolactam), poly(vinylidene fluoride), polylactide, cellulose acetate, and ethyl cellulose. The cloth and nonwoven fabric may be woven or nonwoven fabric made of synthetic or natural fibers such as cotton, nylon, rayon, polyethylene, and polypropylene, glass, ceramic materials, etc. Furthermore, when light is irradiated from the substrate side, the substrate is preferably light-transmitting or transparent.

[0096] The adhesive layer can be disposed on at least one surface of the substrate. The thickness of the adhesive layer varies depending on the application, but is, for example, 1 to 300 μm, and preferably 1 to 30 μm.

[0097] If necessary, a release paper or release film may be laminated on the adhesive layer.

[0098] The adhesive film may be formed by applying an adhesive composition to a substrate and then drying the applied composition, or by transferring an adhesive layer containing the adhesive composition formed on a release sheet to a substrate. Drying is preferably carried out at a temperature at which volatile components such as solvents in the adhesive composition can be removed, for example, at 80 to 160°C.

[0099] When the pressure-sensitive adhesive composition contains a crosslinking agent, the polymer may be pre-crosslinked with the crosslinking agent. That is, the polymer may be crosslinked by reacting a part of the acidic functional groups of the structural unit (B) of the polymer with the crosslinking agent. The crosslinking with the crosslinking agent is usually thermal crosslinking. The heating temperature may be a temperature at which thermal crosslinking can occur, for example, 80 to 160°C.

[0100] 4.Applications The pressure-sensitive adhesive composition can be used, for example, for temporary adhesion to an adherend. That is, a method for using the pressure-sensitive adhesive composition includes the steps of 1) applying an adhesive layer containing the pressure-sensitive adhesive composition to an adherend, and 2) irradiating the adhesive layer with light to weaken the adhesive strength of the adhesive layer, and then peeling the adhesive layer from the adherend.

[0101] 2A and 2B are schematic cross-sectional views showing examples of use of an adhesive film. In these figures, an adhesive film 10 has a substrate 11 and an adhesive layer 12. A device 20 may be placed and fixed on the adhesive layer 12 of the adhesive film 10 (see FIG. 2A), or the adhesive layer 12 of the adhesive film 10 may be adhered to a supporting substrate 30, and the device 20 may be placed and fixed on the substrate 11 via another adhesive 40 (see FIG. 2B). In FIG. 2A, light may be irradiated from the substrate 11 side, and in FIG. 2B, light may be irradiated from the supporting substrate 30 side.

[0102] The type of adherend is not particularly limited, but may be, for example, a wafer, a chip, glass, or the like.

[0103] 2A can be used as a process film in the manufacturing process of semiconductor products, specifically as a back-grinding film or dicing film. A method for dicing a wafer using the above-mentioned adhesive film will be described below.

[0104] First, a wafer is attached to the adhesive layer of the adhesive film. In this attached state, the wafer undergoes processes such as dicing, cleaning, and drying. During this process, the individual chips are sufficiently adhered and held in place by the adhesive layer, so they do not fall off during each of the above processes.

[0105] Next, each chip is picked up from the adhesive film and mounted on a predetermined base. At this time, prior to or during the pick-up, light is irradiated onto the adhesive layer through the substrate. This reduces the adhesive strength of the adhesive layer to a level that allows pick-up.

[0106] The light to be irradiated may have a wavelength that can photodecompose the photobase generator, for example, light with a wavelength of 200 to 400 nm, preferably ultraviolet (UV) or electron beam (EB). The irradiation amount (cumulative light amount) of the irradiated light may be sufficient to allow peeling, for example, 10 to 9000 mW / cm. 2 It is possible.

[0107] After the expanding process, the chip to be picked up is pushed up from the underside of the substrate by a push-up pin, and then picked up by, for example, a suction collet and mounted on a predetermined base. At this point, the adhesive force has sufficiently decreased, so that good quality chips can be obtained with little damage due to heat. [Example]

[0108] The present disclosure will be described in more detail below with reference to examples and comparative examples, but the present disclosure is not limited thereto. Note that the number of parts in the examples and comparative examples is by mass unless otherwise specified.

[0109] 1. Monomer materials (Structural unit (A)) Butyl acrylate 2-Ethylhexyl Acrylate

[0110] (Structural unit (B)) Acrylic acid 2-Acryloyloxyethyl succinate (HOA-MS(N) manufactured by Kyoeisha Chemical Co., Ltd.) 4-Hydroxyphenyl methacrylate (HQMA-H manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0111] (Structural unit (C)) 4-(Methacryloyloxy)piperidine-1-carboxylate (2-nitrophenyl)methyl (Fujifilm Wako Pure Chemical Industries, Ltd., WPBG-165, see formula below) [ka]

[0112] 2. Preparation of Polymer Solutions <Preparation of polymer solution 1> 8.0 g of butyl acrylate, 0.20 g of acrylic acid, and 21 g of ethyl acetate were mixed, and then 1.0 g of 4-(methacryloyloxy)piperidine-1-carboxylate (2-nitrophenyl)methyl (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., WPBG-165) was dissolved therein to obtain a monomer solution. On the other hand, 0.18 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (V-65, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 10 g of ethyl acetate to obtain an initiator solution. Then, 565 μL of the initiator solution was added to the monomer solution heated to 50°C under a nitrogen atmosphere. This was heated under a nitrogen atmosphere with stirring for 1 hour, and then 565 μL of the initiator solution was added again and heated for an additional 7 hours. This was allowed to cool to room temperature and left to stand for 14 hours or more, and then heated again under a nitrogen atmosphere at 50°C for 9 hours with stirring to obtain polymer solution 1 containing a crosslinkable acrylic polymer.

[0113] <Preparation of polymer solution 2> Polymer solution 2 containing a crosslinkable acrylic polymer was obtained in the same manner as polymer solution 1, except that the amount of acrylic acid was changed to 0.33 g, the amount of ethyl acetate in the monomer solution was changed to 23 g, and the amount of 4-(methacryloyloxy)piperidine-1-carboxylate (2-nitrophenyl)methyl was changed to 1.6 g.

[0114] <Preparation of polymer solution 3> Polymer solution 3 containing a crosslinkable acrylic polymer was obtained in the same manner as in Example 1, except that the amount of acrylic acid was changed to 0.45 g, the amount of ethyl acetate in the monomer solution was changed to 23 g, and the amount of 4-(methacryloyloxy)piperidine-1-carboxylate (2-nitrophenyl)methyl was changed to 2.0 g.

[0115] <Preparation of polymer solution 4> 8.0 g of butyl acrylate, 0.61 g of 2-acryloyloxyethyl succinic acid (HOA-MS(N) manufactured by Kyoeisha Chemical Co., Ltd.), and 23 g of ethyl acetate were mixed, and then 1.0 g of 4-(methacryloyloxy)piperidine-1-carboxylate (2-nitrophenyl)methyl (WPBG-165 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved to obtain a monomer solution. On the other hand, 0.18 g of 2,2'-azobis(isobutyronitrile) was dissolved in 10 g of ethyl acetate to obtain an initiator solution. Then, 565 μL of the initiator solution was added to the monomer solution heated to 65° C. under a nitrogen atmosphere. This was heated under a nitrogen atmosphere with stirring for 1 hour, and then 565 μL of the initiator solution was added again and heated for an additional 7 hours. This was allowed to cool to room temperature and left to stand for 14 hours or more, and then heated again under a nitrogen atmosphere at 65° C. with stirring for 9 hours to obtain polymer solution 4 containing a crosslinkable acrylic polymer.

[0116] <Preparation of Polymer Solution 5> Polymer solution 5 containing a crosslinkable acrylic polymer was obtained in the same manner as polymer solution 1, except that 0.20 g of acrylic acid was changed to 0.50 g of 4-hydroxyphenyl methacrylate (HQMA-H manufactured by Osaka Organic Chemical Industry Co., Ltd.) and the amount of ethyl acetate in the monomer solution was changed to 23 g.

[0117] <Preparation of Polymer Solution 6> Polymer solution 6 containing a crosslinkable acrylic polymer was obtained in the same manner as polymer solution 1, except that butyl acrylate was changed to 8.0 g of 2-ethylhexyl acrylate.

[0118] <Preparation of Polymer Solution 7> Polymer solution 7 containing a crosslinkable acrylic polymer was obtained in the same manner as polymer solution 3, except that butyl acrylate was changed to 8.0 g of 2-ethylhexyl acrylate and 0.46 g of acrylic acid.

[0119] <Preparation of Polymer Solution 8> Polymer solution 8 containing a crosslinkable acrylic polymer was obtained in the same manner as polymer solution 1, except that acrylic acid was not added.

[0120] <Preparation of Polymer Solution 9> Polymer solution 9 containing a crosslinkable acrylic polymer was obtained in the same manner as polymer solution 1, except that the amount of ethyl acetate in the monomer solution was changed to 20 g and 4-(methacryloyloxy)piperidine-1-carboxylate (2-nitrophenyl)methyl was not added.

[0121] <Preparation of Polymer Solution 10> Polymer solution 10 containing a crosslinkable acrylic polymer was obtained in the same manner as polymer solution 1, except that the amount of acrylic acid was changed to 0.05 g and the amount of (2-nitrophenyl)methyl 4-(methacryloyloxy)piperidine-1-carboxylate was changed to 0.25 g.

[0122] <Preparation of Polymer Solution 11> Polymer solution 11 containing an acrylic polymer was obtained in the same manner as polymer solution 1, except that 0.20 g of acrylic acid was changed to 1.1 g of 4-hydroxyphenyl methacrylate (HQMA-H manufactured by Osaka Organic Chemical Industry Co., Ltd.), 1.0 g of 4-(methacryloyloxy)piperidine-1-carboxylate (2-nitrophenyl)methyl (WPBG-165 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was changed to 1.0 g of N-[3-(dimethylamino)propyl]acrylamide, and the amount of ethyl acetate in the monomer solution was changed to 22 g.

[0123] <Preparation of Polymer Solution 12> Polymer solution 12 containing an acrylic polymer was obtained in the same manner as polymer solution 1, except that 0.20 g of acrylic acid was changed to 1.1 g of 4-hydroxyphenyl methacrylate (HQMA-H manufactured by Osaka Organic Chemical Industry Co., Ltd.), 1.0 g of 4-(methacryloyloxy)piperidine-1-carboxylate (2-nitrophenyl)methyl (WPBG-165 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was changed to 1.0 g of 2,2,6,6-tetramethyl-4-piperidyl methacrylate, and the amount of ethyl acetate in the monomer solution was changed to 22 g.

[0124] <Preparation of polymer solution α> 8.0 g of butyl acrylate, 2.0 g of 4-(methacryloyloxy)piperidine-1-carboxylate (2-nitrophenyl)methyl (WPBG-165, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 23 g of ethyl acetate were mixed to obtain a monomer solution. Also, 0.18 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (V-65, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 10 g of ethyl acetate to obtain an initiator solution. Furthermore, 565 μL of the initiator solution was added to the monomer solution heated to 50°C under a nitrogen atmosphere. After heating these for 1 hour under a nitrogen atmosphere with stirring, 565 μL of the initiator solution was added again and heated for another 7 hours. After cooling to room temperature and leaving to stand for 14 hours or more, it was again heated at 50°C under a nitrogen atmosphere with stirring for 9 hours to obtain polymer solution α containing a crosslinkable acrylic polymer.

[0125] <Preparation of polymer solution β> A monomer solution was obtained by mixing 8.0 g of butyl acrylate, 0.47 g of acrylic acid, and 20 g of ethyl acetate. Also, 0.18 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (V-65, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 10 g of ethyl acetate to obtain an initiator solution. Furthermore, 565 μL of the initiator solution was added to the monomer solution heated to 50°C under a nitrogen atmosphere. After heating these for 1 hour under a nitrogen atmosphere with stirring, 565 μL of the initiator solution was added again and heated for another 7 hours. After allowing to cool to room temperature and leaving to stand for 14 hours or more, it was again heated at 50°C under a nitrogen atmosphere with stirring for 9 hours to obtain a polymer solution β containing an acrylic polymer.

[0126] <Evaluation> The weight average molecular weight (Mw) and dispersity (Mw / Mn) of the obtained polymer solutions 1 to 12, α, and β were measured by the following methods.

[0127] (molecular weight measurement) The Mw and Mw / Mn of the resulting polymer were measured using gel permeation chromatography (GPC) in terms of standard polystyrene. The GPC analysis conditions are as follows:

[0128] [Polymer solutions 1 to 10, α and β] Automatic injection device: 717plus, manufactured by Japan Waters Pump: Nippon Waters 515 HPLC pump Column: Showa Denko PLgel 10μ MIXED-B, 7.5 x 300 mm (3 columns) Refractive index detector: Showa Denko, Shodex R-101 Column calibration: Agilent Technologies, EasiCal PS-1 polystyrene Eluent: tetrahydrofuran for HPLC, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Column temperature: 40℃ Flow rate: 1.0ml / min

[0129] [Polymer solutions 11 and 12] Automatic injection device: 717plus, manufactured by Japan Waters Pump: Fromm KP-22-13 dual pump Column: Tosoh TSKgel 9μ SuperAWM-H, 6.0 x 150 mm (2 columns) Refractive index detector: Showa Denko, Shodex RI-101 Column calibration: Agilent Technologies, EasiVial PS-H polystyrene Eluent: Fujifilm Wako Pure Chemical Industries, GPC grade dimethylformamide, 10 mM LiBr added Column temperature: 40℃ Flow rate: 0.6ml / min

[0130] Table 1 shows the polymer compositions and physical properties of polymer solutions 1 to 12, α and β.

[0131] [Table 1]

[0132] 3. Preparation and evaluation of adhesive film (Examples 1, 3, 4, 6, 7, 9, 10 and Comparative Examples 1 to 3) The polymer solution shown in Table 2 was applied to a substrate (PEN (polyethylene naphthalate) film, Teonex Q83C manufactured by Toyobo Co., Ltd., thickness 50 μm) and dried in an oven at 120° C. for 5 minutes. As a result, an adhesive film having an adhesive layer with the thickness shown in Table 2 was obtained.

[0133] Example 2 A crosslinker solution was prepared by mixing 0.1 g of a crosslinker (Orgatix TC-401, manufactured by Matsumoto Fine Chemical Co., Ltd., titanium tetraacetylacetonate, component concentration 65% by mass) with 9.9 g of ethyl acetate. 0.033 g of this crosslinker solution was added to 5.0 g of polymer solution 1 and mixed thoroughly to obtain an adhesive composition containing a crosslinkable acrylic polymer and a crosslinker. The content of the crosslinker was 0.015 parts by mass per 100 parts by mass of the crosslinkable acrylic polymer. An adhesive film was then obtained in the same manner as in Example 1, except that the obtained adhesive composition was used.

[0134] Example 5 Polymer solution 3 was applied to a substrate (PET (polyethylene terephthalate) film, Toray Industries, Inc., Lumirror #100-U34, thickness 100 μm) and dried in an oven at 120° C. for 5 minutes, thereby obtaining an adhesive film having an adhesive layer with a thickness of 7 μm.

[0135] Example 8 A pressure-sensitive adhesive composition was obtained by mixing 3.0 g of the obtained polymer solution α and 2.4 g of the polymer solution β. A pressure-sensitive adhesive film having a 7 μm-thick pressure-sensitive adhesive layer was obtained in the same manner as in Example 1, except that the obtained pressure-sensitive adhesive composition was used.

[0136] Example 11 A pressure-sensitive adhesive composition was obtained by mixing 2.3 g of the obtained polymer solution α and 2.7 g of the polymer solution β. A pressure-sensitive adhesive film having a pressure-sensitive adhesive layer with a thickness of 8 μm was obtained in the same manner as in Example 1, except that the obtained pressure-sensitive adhesive composition was used.

[0137] Example 12 A pressure-sensitive adhesive composition was obtained by mixing 4.1 g of the obtained polymer solution α and 1.2 g of the polymer solution β. A pressure-sensitive adhesive film having a 6 μm-thick pressure-sensitive adhesive layer was obtained in the same manner as in Example 1, except that the obtained pressure-sensitive adhesive composition was used.

[0138] Example 13 A solution was prepared by mixing 0.38 g of 2-(9-oxoxanthen-2-yl)propionic acid, an ionic additive, with 3.0 g of ethyl acetate. This solution was added to 7.0 g of polymer solution 11 and mixed thoroughly to react the acrylic polymer N-[3-(dimethylamino)propyl]acrylamide with 2-(9-oxoxanthen-2-yl)propionic acid, thereby obtaining a pressure-sensitive adhesive composition containing a crosslinkable acrylic polymer. The amount of 2-(9-oxoxanthen-2-yl)propionic acid added was 17 parts by mass relative to 100 parts by mass of the acrylic polymer. An adhesive film was then obtained in the same manner as in Example 1, except that the obtained pressure-sensitive adhesive composition was used.

[0139] Example 14 A solution was prepared by mixing 0.37 g of ketoprofen, an ionic additive, with 3.2 g of ethyl acetate. This solution was added to 2.5 g of polymer solution 12 and mixed thoroughly to react the ketoprofen with the acrylic polymer 2,2,6,6-tetramethyl-4-piperidyl methacrylate, thereby obtaining a pressure-sensitive adhesive composition containing a crosslinkable acrylic polymer. The amount of ketoprofen added was 43 parts by mass per 100 parts by mass of the acrylic polymer. An adhesive film was then obtained in the same manner as in Example 1, except that the obtained pressure-sensitive adhesive composition was used.

[0140] (evaluation) The peel strength of the pressure-sensitive adhesive films of Examples 1 to 14 and Comparative Examples 1 to 3 was measured by the following method.

[0141] (peel force test) A 25 mm wide adhesive film was placed on a water slide (S7213, manufactured by Matsunami Glass Industry Co., Ltd.) to prepare a sample. When light irradiation was used, the film was irradiated according to the light irradiation method described below, and then a peel test was conducted using a peel tester (Strograph ES, manufactured by Toyo Seiki Seisakusho Co., Ltd.) to peel the adhesive film from the glass at a peel angle of 180° at a speed of 300 mm / min. Three samples per sample (n=3) were measured, and the average value was calculated.

[0142] Light irradiation method An LED lighting device (HLKK60, manufactured by Pi Photonics) was used for light irradiation. The LED lighting device was placed 8.5 cm away from the sample so that the diameter of the light spot irradiated on the sample was 1 cm. The sample was moved while maintaining the distance between the LED lighting device and the sample, and the entire sample was sufficiently irradiated. The light irradiation direction (i.e., whether the light was irradiated from the glass side or the adhesive film substrate side) is listed in Table 2. The intensity of the light irradiated onto the sample was measured using an illuminance meter (UV PowerPuck II, manufactured by EIT Co., Ltd.). The UVA intensity was 1926 mW / cm when the illuminance meter was placed 8.5 cm away from the LED lighting device. 2 , the diameter of the light spot was 1 cm and the diameter of the illuminance meter detector was 2 cm, so the value was 7705 mW / cm 2It was converted as follows.

[0143] The evaluation results of the PSA films of Examples 1 to 14 and Comparative Examples 1 to 3 are shown in Table 2. In Table 2, for Examples 8, 11, and 12, the content of each structural unit indicates the ratio (parts by mass) to the total amount of the structural units of polymers α and β.

[0144] [Table 2]

[0145] As shown in Table 2, the adhesive films of Examples 1 to 14, which use crosslinkable acrylic polymers or adhesive compositions containing structural units (A), (B), and (C) in a predetermined ratio, exhibit high adhesiveness before light irradiation, but show reduced adhesiveness and good peelability after light irradiation.

[0146] In particular, it was found that a blend of polymer α containing structural units (A) and (B) and polymer β containing structural units (A) and (C) also exhibited good releasability, similar to the case where a crosslinkable acrylic polymer containing structural units (A), (B), and (C) was used (Comparison of Example 1 with Examples 8, 10, and 11).

[0147] It is also clear that the peelability after light irradiation is further improved by further increasing the content of the structural unit (C) (comparison of Examples 1, 3 and 4).

[0148] Furthermore, it can be seen that by setting the total ratio of the structural unit (B) and the structural unit (C) (B+C) / A to 10 / 90 to 30 / 70 (mass ratio), the adhesiveness before light irradiation and the releasability after light irradiation are further improved (comparison between Examples 1, 3, and 4).

[0149] Furthermore, it is clear that by adjusting the molar ratio C / B of the structural unit (B) to the structural unit (C) to 0.4 to 2.5, the peelability after light irradiation is further improved (comparison of Examples 8, 11, and 12).

[0150] It is also clear that the inclusion of a crosslinking agent further improves the adhesion before light irradiation and the releasability after light irradiation (comparison between Examples 1 and 2).

[0151] In contrast, the adhesive film of Comparative Example 1, which uses a crosslinkable acrylic polymer not containing the structural unit (B), the adhesive film of Comparative Example 2, which uses an acrylic polymer not containing the structural unit (C), and the adhesive film of Comparative Example 3, which uses a crosslinkable acrylic polymer with a small amount of the structural unit (C), all show almost no decrease in adhesion after light irradiation and have low peelability. In particular, the adhesive film of Comparative Example 3 (unlike Examples 1, 3, and 4) shows that its adhesion actually increases after light irradiation compared to before light irradiation, making it more difficult to peel. This is presumably because the elastic modulus before light irradiation is too low, so that the peel force also increases with the increase in elastic modulus even after light irradiation (see Figure 1).

[0152] 4. Evaluation of mass change rate of adhesive film before and after light irradiation (Examples 15 to 19, 21, and 22 and Comparative Examples 4 to 6) The polymer solution shown in Table 3 was applied to a polyethylene terephthalate film that had been treated with a silicone release agent, and then dried in an oven at 120°C for 5 minutes. This formed an adhesive layer with the thickness shown in Table 3. The thickness of the adhesive layer was adjusted to fall within the range of 1 to 45 μm. The resulting adhesive layer was transferred onto aluminum foil (substrate) to obtain an adhesive film.

[0153] Example 20 A pressure-sensitive adhesive composition was obtained by mixing 3.0 g of the obtained polymer solution α and 2.4 g of the polymer solution β. A pressure-sensitive adhesive film was obtained in the same manner as in Example 15, except that the obtained pressure-sensitive adhesive composition was used.

[0154] Example 23 A pressure-sensitive adhesive composition was obtained by mixing 2.0 g of polymer solution α and 2.4 g of polymer solution β so that the mass ratio of the obtained polymer solutions α and β was the same as in Example 11. A pressure-sensitive adhesive film was obtained in the same manner as in Example 15, except that the obtained pressure-sensitive adhesive composition was used.

[0155] Example 24 A pressure-sensitive adhesive composition was obtained by mixing 4.1 g of the obtained polymer solution α and 1.2 g of the polymer solution β. A pressure-sensitive adhesive film was obtained in the same manner as in Example 15, except that the obtained pressure-sensitive adhesive composition was used.

[0156] Example 25 A solution was prepared by mixing 0.38 g of 2-(9-oxoxanthen-2-yl)propionic acid, an ionic additive, with 3.0 g of ethyl acetate. This solution was added to 7.0 g of polymer solution 11 and mixed thoroughly to react the acrylic polymer N-[3-(dimethylamino)propyl]acrylamide with 2-(9-oxoxanthen-2-yl)propionic acid, thereby obtaining a pressure-sensitive adhesive composition containing a crosslinkable acrylic polymer. The amount of 2-(9-oxoxanthen-2-yl)propionic acid added was 17 parts by mass per 100 parts by mass of the acrylic polymer. An adhesive film was then obtained in the same manner as in Example 15, except that the obtained pressure-sensitive adhesive composition was used.

[0157] Example 26 A solution was prepared by mixing 0.37 g of ketoprofen with 3.2 g of ethyl acetate. This solution was added to 2.5 g of polymer solution 12 and mixed thoroughly, thereby reacting ketoprofen with the acrylic polymer 2,2,6,6-tetramethyl-4-piperidyl methacrylate, thereby obtaining a pressure-sensitive adhesive composition containing a crosslinkable acrylic polymer. The ketoprofen content was 43 parts by mass relative to 100 parts by mass of the acrylic polymer. An adhesive film was then obtained in the same manner as in Example 15, except that the obtained pressure-sensitive adhesive composition was used.

[0158] The mass loss due to light irradiation of the pressure-sensitive adhesive films of Examples 15 to 26 and Comparative Examples 4 to 6 was measured by the following method.

[0159] (Evaluation of mass loss) The adhesive layer of the adhesive film was irradiated with light by the light irradiation method described below, and the mass of the adhesive layer was measured before and after the light irradiation. The mass loss rate (%) was defined and calculated according to the following formula. Mass reduction rate (%) = difference in mass of adhesive layer before and after light irradiation (g) / mass of adhesive layer before light irradiation (g) × 100 The greater the mass loss, the more likely interfacial peeling occurs, meaning that peeling is high.

[0160] Light irradiation method A conveyor-type electrodeless UV lighting device (Heraeus, CV-110Q-G) was used for light irradiation. Using an illuminance meter (EIT, UV PowerPuck II), the cumulative UVA irradiation was measured at 7488 mJ / cm. 2 It was.

[0161] The evaluation results of the pressure-sensitive adhesive films of Examples 15 to 26 and Comparative Examples 4 to 6 are shown in Table 3.

[0162] [Table 3]

[0163] As shown in Table 3, the adhesive films of Examples 15 to 22, which use a crosslinkable acrylic polymer or adhesive composition containing structural units (A), (B), and (C) in a specified ratio, have a mass change rate due to light irradiation of more than 1.0%.

[0164] In contrast, the comparative example using a crosslinkable acrylic polymer with a small amount of structural unit (C) 6 It can be seen that the mass change rate of the adhesive film due to light irradiation is less than 1.0%. Furthermore, in Comparative Example 4 (corresponding to Comparative Example 1 in Table 2), which does not contain structural unit (B), the mass change rate was 1.0% or more, which is thought to be due to the elimination of the protecting group in the structural unit (C) and the generation of by-product gases. However, as described above, the adhesiveness after light irradiation hardly decreased, and the peelability was poor. This indicates that, in order to obtain the effects of the present invention, it is important not only to prevent the generation of by-product gases, but also to ensure that the base generated from the structural unit (C) and the acidic functional group of the structural unit (B) undergo an acid-base reaction to form ionic crosslinks.

[0165] This application claims priority from Japanese Patent Application No. 2022-90893, filed June 3, 2022. The contents of the specification and drawings of that application are incorporated herein by reference in their entirety. [Industrial Applicability]

[0166] According to the present invention, a crosslinkable (meth)acrylic polymer can be provided that has good adhesive properties and can be easily peeled off even at low temperatures while reducing damage to adherends, and is therefore suitable for use as a processing film used in the manufacturing process of various products, particularly a processing film that must be peeled off at low temperatures. [Explanation of symbols]

[0167] 10 adhesive film 11 Base material 12 Adhesive layer 20 devices 30 Supporting base material 40 Other adhesives

Claims

1. An adhesive composition for a process film used in the manufacturing process of semiconductor parts or electronic parts, comprising: The present invention relates to a crosslinkable (meth)acrylic polymer having a structural unit (A) derived from a (meth)acrylic acid alkyl ester compound, a structural unit (B) derived from a compound having an acidic functional group, and a structural unit (C) derived from a photobase generator that is decomposed by light irradiation to generate a base and generate a gas, relative to the total amount of structural units in the crosslinkable (meth)acrylic polymer The content of the structural unit (A) is 60.0% by mass or more, The content of the structural unit (B) is 1.0% by mass or more, The content of the structural unit (C) is 6.0% by mass or more, and The total content of the structural units (A), (B), and (C) is 100% by mass or less, and a ratio (B+C) / A of the total content of the structural unit (B) and the structural unit (C) to the content of the structural unit (A) is 13 / 87 to 40 / 60 (mass ratio); When peeling, the adhesive strength is reduced by light irradiation, and the film is peeled off. Adhesive composition.

2. An adhesive composition for a process film used in the manufacturing process of semiconductor parts or electronic parts, comprising: The present invention relates to a crosslinkable (meth)acrylic polymer having a structural unit (A) derived from a (meth)acrylic acid alkyl ester compound, a structural unit (B) derived from a compound having an acidic functional group, and a structural unit (C) derived from a photobase generator that is decomposed by light irradiation to generate a base and generate a gas, The pressure-sensitive adhesive composition was formed into a molded article having a thickness in the range of 1 to 45 μm, and the cumulative irradiation dose was 7488 mJ / cm ２ When irradiated with ultraviolet light, the mass loss rate represented by the following formula is 2.5% or more, When peeling, the adhesive strength is reduced by light irradiation, and the film is peeled off. Adhesive composition. Mass reduction rate (%) = mass difference (g) of the molded body before and after irradiation / mass (g) of the molded body before irradiation × 100

3. The photobase generator contains a group derived from an oxime ester or a carbamate. The adhesive composition according to claim 1 or 2.

4. The structural unit (C) is derived from a compound represented by the following formula: The adhesive composition according to claim 1 or 2. 【Chemistry 1】 (In formula (2-1), X １ and X ２ are independently —O— or —NH—, R １ is H or a methyl group, R １２ is H or a substituted or unsubstituted C1-C4 alkyl group, R １３ is a substituted or unsubstituted polyvalent alkyl group, a substituted or unsubstituted cycloalkylene group, or a substituted or unsubstituted arylene group, and R １２ and R １３ may be bonded to each other to form a ring, R １４ is a substituted or unsubstituted alkylene group, R １５ is a nitro group or an alkoxy group, n is an integer from 0 to 2, y is an integer from 1 to 3.

5. a ratio (B+C) / A of the total content of the structural unit (B) and the structural unit (C) to the content of the structural unit (A) is 13 / 87 to 30 / 70 (mass ratio); The adhesive composition according to claim 1 or 2.

6. the content ratio C / B of the structural unit (B) to the structural unit (C) is 0.4 to 2.5 (molar ratio); The adhesive composition according to claim 1 or 2.

7. the number of carbon atoms in the alkyl chain of the (meth)acrylic acid alkyl ester compound is 2 to 20; The adhesive composition according to claim 1 or 2.

8. The weight average molecular weight of the crosslinkable (meth)acrylic polymer is 200,000 or more. The adhesive composition according to claim 1 or 2.

9. The dispersity (Mw / Mn) of the crosslinkable (meth)acrylic polymer is 2.0 to 8.

0. The adhesive composition according to claim 1 or 2.

10. further comprising a cross-linking agent, The adhesive composition according to claim 1 or 2.

11. the content of the crosslinking agent is 0.00 to 2.00 parts by mass relative to 100 parts by mass of the crosslinkable (meth)acrylic polymer; The adhesive composition according to claim 10.

12. An adhesive composition for a process film used in the manufacturing process of semiconductor parts or electronic parts, comprising: a polymer α having a structural unit (A) derived from a (meth)acrylic acid alkyl ester compound; a polymer β having a structural unit (B) derived from a compound having an acidic functional group; An adhesive composition comprising: at least one of the polymer α and the polymer β further contains a structural unit (C) derived from a photobase generator that is decomposed by light irradiation to generate a base and generate a gas, relative to the total amount of structural units of the polymer α and the polymer β, The content of the structural unit (A) is 60.0% by mass or more, The content of the structural unit (B) is 1.0% by mass or more, The content of the structural unit (C) is 6.0% by mass or more, and The total content of the structural units (A), (B), and (C) is 100% by mass or less, and a ratio (B+C) / A of the total content of the structural unit (B) and the structural unit (C) to the content of the structural unit (A) is 13 / 87 to 40 / 60 (mass ratio); When peeling, the adhesive strength is reduced by light irradiation, and the film is peeled off. Adhesive composition.

13. An adhesive composition for a process film used in the manufacturing process of semiconductor parts or electronic parts, comprising: a polymer α having a structural unit (A) derived from a (meth)acrylic acid alkyl ester compound; a polymer β having a structural unit (B) derived from a compound having an acidic functional group; An adhesive composition comprising: at least one of the polymer α and the polymer β further contains a structural unit (C) derived from a photobase generator that is decomposed by light irradiation to generate a base and generate a gas, The pressure-sensitive adhesive composition molded article adjusted to have a thickness in the range of 1 to 45 μm was exposed to an accumulated irradiation dose of 7488 mJ / cm ２ When irradiated with ultraviolet light, the mass loss rate of the molded body, as represented by the following formula, is 2.5% or more, When peeling, the adhesive strength is reduced by light irradiation, and the film is peeled off. Adhesive composition. Mass reduction rate (%) = mass difference (g) of the molded body before and after irradiation / mass (g) of the molded body before irradiation × 100

14. An adhesive layer comprising the adhesive composition according to any one of claims 1, 2, 12 and 13. Adhesive material.

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