Adhesive composition, adhesive tape, semiconductor wafer processing method, and semiconductor device manufacturing method

Abstract

The present invention aims to provide an adhesive composition that can achieve both excellent embedding properties for uneven surfaces and excellent peeling performance. Furthermore, it aims to provide an adhesive tape having an adhesive layer formed using the adhesive composition. Moreover, the present invention aims to provide a method for processing semiconductor wafers and a method for manufacturing semiconductor devices using the adhesive tape. [Solution] An adhesive composition containing a (meth)acrylic copolymer, wherein the (meth)acrylic copolymer comprises constituent units derived from alkyl (meth)acrylate having a linear or branched C6 alkyl group, and the (meth)acrylic copolymer has a carbon-carbon double bond in its side chain.

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition. Furthermore, the present invention relates to an adhesive tape having an adhesive layer formed using the adhesive composition. Moreover, the present invention relates to a method for processing semiconductor wafers and a method for manufacturing semiconductor devices using the adhesive tape. [Background technology]

[0002] Conventionally, adhesive tapes having an adhesive layer containing an adhesive composition have been widely used to fix parts in electronic devices, vehicles, houses, and building materials (for example, Patent Documents 1 to 3). Specifically, for example, adhesive tapes are used to adhere a cover panel for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to adhere a touch panel module to a display panel module. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2015-052050 [Patent Document 2] Japanese Patent Publication No. 2015-021067 [Patent Document 3] Japanese Patent Publication No. 2015-120876 [Overview of the project] [Problems that the invention aims to solve]

[0004] Conventionally, acrylic adhesives containing (meth)acrylic copolymers have been widely used as adhesive compositions with excellent adhesive strength. Examples of acrylic monomers that make up the (meth)acrylic copolymer include alkyl (meth)acrylate esters such as n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate.

[0005] Adhesive compositions and adhesive tapes used for temporarily fixing electronic components such as semiconductors require excellent embedding properties with respect to uneven surfaces because uneven surfaces exist on the surface of a bump wafer or the like to be temporarily fixed. In addition, there is a need to be able to peel off while suppressing the generation of adhesive residue (residue) from the electronic components to be temporarily fixed, and excellent peeling performance is also required. However, when an acrylic adhesive containing a (meth)acrylic copolymer using n-butyl (meth)acrylate as the main component of the raw material is used, the embedding property with respect to uneven surfaces is insufficient. On the other hand, when an acrylic adhesive containing a (meth)acrylic copolymer using 2-ethylhexyl (meth)acrylate as the main component of the raw material is used, although it has excellent embedding property with respect to uneven surfaces, there is a problem that it is likely to be torn during peeling and adhesive residue is likely to occur on the electronic components to be temporarily fixed.

[0006] An object of the present invention is to provide an adhesive composition capable of achieving both excellent embedding property with respect to uneven surfaces and excellent peeling performance. Another object of the present invention is to provide an adhesive tape having an adhesive layer formed using the adhesive composition. Furthermore, an object of the present invention is to provide a method for processing a semiconductor wafer and a method for manufacturing a semiconductor device using the adhesive tape.

Means for Solving the Problems

[0007] The present disclosure 1 is an adhesive composition containing a (meth)acrylic copolymer, wherein the (meth)acrylic copolymer contains a structural unit derived from an alkyl (meth)acrylate having a linear or branched alkyl group having 6 carbon atoms, and the (meth)acrylic copolymer has a carbon-carbon double bond in the side chain. The present disclosure 2 is the adhesive composition of the present disclosure 1, wherein the alkyl (meth)acrylate having a linear or branched alkyl group having 6 carbon atoms contains n-hexyl (meth)acrylate. The present disclosure 3 is the adhesive composition of the present disclosure 2, wherein the n-hexyl (meth)acrylate contains a product synthesized from n-hexyl alcohol, which is a bio-derived material, and (meth)acrylic acid. The present disclosure 4 is the adhesive composition of the present disclosure 1, 2, or 3, in which the content ratio of the structural unit derived from the alkyl (meth)acrylate having a linear or branched alkyl group with 6 carbon atoms in the above (meth)acrylic copolymer is 15% by mass or more. The present disclosure 5 is the adhesive composition of the present disclosure 1, 2, 3, or 4, in which the above (meth)acrylic copolymer contains a structural unit derived from a polar functional group-containing monomer. The present disclosure 6 is the adhesive composition of the present disclosure 5, in which the total content ratio of the structural units derived from the above polar functional group-containing monomer in the above (meth)acrylic copolymer is 0.01% by mass or more and 30% by mass or less. The present disclosure 7 is the adhesive composition of the present disclosure 1, 2, 3, 4, 5, or 6, in which the above (meth)acrylic copolymer has a carbon-carbon double bond equivalent of 0.05 meq / g or more. The present disclosure 8 is the adhesive composition of the present disclosure 5, 6, or 7, in which the acid value of the above (meth)acrylic copolymer is 10 mgKOH / g or less. The present disclosure 9 is the adhesive composition of the present disclosure 5, 6, 7, or 8, in which the hydroxyl value of the above (meth)acrylic copolymer is 5.0 mgKOH / g or more and 100 mgKOH / g or less. The present disclosure 10 is the adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, or 9, in which the weight average molecular weight of the above (meth)acrylic copolymer is 200,000 or more and 2,000,000 or less. The present disclosure 11 is the adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, which further contains at least one polymerization initiator selected from the group consisting of a photopolymerization initiator and a thermal polymerization initiator. The present disclosure 12 is the adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11, which further contains an inorganic filler. The present disclosure 13 is the adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, which further contains a polyfunctional oligomer or a polyfunctional monomer. The present disclosure 14 is the adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13, which further contains a gas generating agent. Disclosure 15 further relates to an adhesive composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14, which further contains a tackifier. Disclosure 16 is an adhesive tape having an adhesive layer formed using the adhesive composition of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15. Disclosure 17 is an adhesive tape according to Disclosure 16, wherein the content of bio-derived carbon in the adhesive layer is 10% or more. Disclosure 18 relates to a method in which the gel fraction of the adhesive layer is 10% by mass or more and 90% by mass or less, and after heating at 150°C for 1 hour, or after emitting light of any wavelength within the range of 280 nm to 405 nm with an integrated light intensity of 1000 mJ / cm². 2 The adhesive tape according to disclosure 16 or 17 is characterized in that the gel fraction of the adhesive layer after irradiation to the above-mentioned extent is 90% by mass or more. This disclosure 19 states that the shear storage modulus of the adhesive layer at 23°C is 1.2 × 10⁻⁶. 5 The pressure is less than Pa, and after heating at 150°C for 1 hour, or after emitting light of any wavelength within the range of 280 nm to 405 nm, the integrated light intensity is 1000 mJ / cm². 2 The tensile storage modulus of the adhesive layer at 23°C after irradiation as described above is 1.0 × 10⁻⁶. 6 The adhesive tape according to disclosure 16, 17, or 18, having a Pa of 1 or higher. Disclosure 20 has a 180° peeling force of 0.3 N / 25 mm or more on SUS, and after heating at 150°C for 1 hour, or after emitting light of any wavelength within the range of 280 nm to 405 nm with an integrated light intensity of 1000 mJ / cm² 2 The adhesive tape according to disclosure 16, 17, 18, or 19 is characterized in that the 180° peel force on SUS after irradiation is 0.30 N / 25 mm or less. Disclosure 21 is an adhesive tape of Disclosure 16, 17, 18, 19, or 20 used for temporary fixing of electronic equipment components. Disclosure 22 is a semiconductor wafer processing method comprising the steps of temporarily fixing a semiconductor wafer to a support using the adhesive tape of Disclosure 21, and peeling off the adhesive tape after the adhesive layer has been cured by light or heat. Disclosure 23 is a method for manufacturing a semiconductor device, comprising the steps of temporarily fixing a semiconductor wafer to a support using the adhesive tape of Disclosure 21, and peeling off the adhesive tape after the adhesive layer has been cured by light or heat. The present invention will be described in detail below.

[0008] The inventors have found that in an adhesive composition containing a (meth)acrylic copolymer, using a (meth)acrylic copolymer that includes structural units derived from alkyl (meth)acrylate having linear or branched C6 alkyl groups improves the embedding ability and peeling performance of the adhesive composition. Furthermore, the inventors focused on the fact that curing of the (meth)acrylic copolymer significantly reduces the adhesive strength of the adhesive composition and improves the peeling performance. They investigated how to further enhance the peeling performance of the adhesive composition by introducing carbon-carbon double bonds into the side chains of the (meth)acrylic copolymer containing structural units derived from alkyl (meth)acrylate having linear or branched C6 alkyl groups, thereby creating a structure that can be cured by light irradiation or heating. As a result, we discovered that an adhesive composition can be obtained that achieves both excellent embedding ability for uneven surfaces and excellent peeling performance, thus completing the present invention.

[0009] The adhesive composition of the present invention contains a (meth)acrylic copolymer. The above (meth)acrylic copolymer contains constituent units derived from alkyl (meth)acrylate (hereinafter also referred to as "C6 alkyl (meth)acrylate") having a linear or branched C6 alkyl group. By incorporating the above C6 alkyl (meth)acrylate into the polymer, the glass transition temperature (Tg) of the polymer can be lowered, thereby increasing flexibility and improving the embedding and peeling properties of the adhesive composition against uneven surfaces. Therefore, by having the above (meth)acrylic copolymer contain constituent units derived from the above C6 alkyl (meth)acrylate and having carbon-carbon double bonds in its side chains, the adhesive composition of the present invention can be made to have excellent embedding properties for uneven surfaces, and can be easily peeled off from uneven surfaces while suppressing the generation of adhesive residue, thus having excellent peeling performance. In this specification, "(meth)acrylic" means acrylic or methacrylic, and "(meth)acrylate" means acrylate or methacrylate.

[0010] Examples of the above-mentioned C6 alkyl (meth)acrylate include n-hexyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, 2-methylpentyl (meth)acrylate, and 4-methyl-2-pentyl (meth)acrylate. In particular, it is preferable that the above-mentioned C6 alkyl (meth)acrylate includes n-hexyl (meth)acrylate. By including a constituent unit derived from n-hexyl (meth)acrylate in the above-mentioned (meth)acrylic copolymer, the glass transition temperature (Tg) of the above-mentioned (meth)acrylic copolymer is further reduced, and the storage modulus at room temperature of the adhesive composition of the present invention is further reduced. As a result, the adhesive composition of the present invention exhibits greater flexibility and can conform to rough surfaces more effectively.

[0011] The above-mentioned C6 alkyl (meth)acrylate may consist solely of petroleum-derived materials, but it is preferable that it also contains bio-derived materials. In recent years, the depletion of petroleum resources and the emission of carbon dioxide from the combustion of petroleum-derived products have become serious concerns. Therefore, attempts are being made to conserve petroleum resources by using bio-based materials instead of petroleum-derived materials. By including a bio-derived material in the above-mentioned C6 alkyl (meth)acrylate, the content of bio-derived carbon in the adhesive layer formed using the adhesive composition of the present invention, as described later, is increased, thereby further reducing the environmental impact of the adhesive tape having said adhesive layer. In this specification, "containing bio-derived carbon" means that the bio-based carbon content of the compound, as measured by ASTM D6866-24, is 1% or more.

[0012] When the n-hexyl (meth)acrylate in the constituent unit derived from the above-mentioned n-hexyl (meth)acrylate includes a bio-derived material, it is preferable that the n-hexyl (meth)acrylate includes one synthesized from n-hexyl alcohol, which is a bio-derived material, and (meth)acrylic acid, and it is more preferable that the n-hexyl (meth)acrylate includes one synthesized by esterification of n-hexyl alcohol, which is a bio-derived material, and (meth)acrylic acid. The above-mentioned bio-derived material, n-hexyl alcohol, can be obtained, for example, by using materials extracted from plants and animals (e.g., linoleic acid derived from castor oil) as raw materials, converting them to hexanal using enzymes, and then hydrogenating them.

[0013] The preferred lower limit for the content of the constituent units derived from the C6 alkyl (meth)acrylate in the above (meth)acrylic copolymer is 15% by mass. A content of 15% by mass or more of the constituent units derived from the C6 alkyl (meth)acrylate enhances the flexibility of the adhesive composition of the present invention, resulting in superior embedding properties for uneven surfaces and easier peeling while suppressing the generation of adhesive residue from uneven surfaces. Furthermore, a content of 15% by mass or more of the constituent units derived from the C6 alkyl (meth)acrylate containing bio-derived carbon allows for a higher content of bio-derived carbon in the adhesive layer of the adhesive tape described later. A more preferred lower limit for the content of the constituent units derived from the C6 alkyl (meth)acrylate is 35% by mass, and an even more preferred lower limit is 50% by mass. Furthermore, there is no particular upper limit to the content of the constituent units derived from the above-mentioned C6 alkyl (meth)acrylate, but since the above-mentioned (meth)acrylic copolymer preferably contains constituent units derived from polar functional group-containing monomers described later and constituent units derived from functional group-containing unsaturated compounds described later, a preferred upper limit is 98% by mass. A more preferred upper limit for the content of the constituent units derived from the above-mentioned C6 alkyl (meth)acrylate is 95% by mass, an even more preferred upper limit is 90% by mass, and an even more preferred upper limit is 85% by mass. In this specification, the content ratio of constituent units in the above (meth)acrylic copolymer is determined by mass spectrometry and / or nuclear magnetic resonance spectroscopy of the above (meth)acrylic copolymer. 1 H-NMR measurement, 13 The content can be calculated by performing measurements such as 13C-NMR and determining the integral intensity ratio of the hydrogen peaks originating from the monomers that make up the constituent units to be measured.

[0014] The above (meth)acrylic copolymer has a carbon-carbon double bond in its side chain. Because the above (meth)acrylic copolymer has carbon-carbon double bonds in its side chains, it can be cured by heating, light irradiation, etc., which significantly reduces the adhesive strength of the adhesive composition of the present invention, making it easier to peel off when the adhesive composition of the present invention is peeled off. Therefore, by having the above-mentioned (meth)acrylic copolymer contain constituent units derived from the above-mentioned C6 alkyl (meth)acrylate and have carbon-carbon double bonds in its side chains, the adhesive composition of the present invention can achieve both excellent embedding properties for uneven surfaces and excellent peeling performance. In this specification, "side chain" refers to the branched structural portion extending from the longest chain in the (meth)acrylic copolymer, when the longest chain is considered the main chain. Furthermore, in this specification, the term "carbon-carbon double bond" does not include carbon-carbon double bonds that constitute an aromatic ring.

[0015] As a method for introducing a carbon-carbon double bond into the side chain of the above-mentioned (meth)acrylic copolymer, for example, one method involves copolymerizing the above-mentioned C6 alkyl (meth)acrylate, a polar functional group-containing monomer described later, or other monomers described later to obtain a carbon-carbon double bond-less (meth)acrylic polymer, and reacting it with a compound having a functional group that can react with carboxyl groups, hydroxyl groups, etc. in the polymer, and a carbon-carbon double bond (hereinafter also referred to as a "functional group-containing unsaturated compound"), or a monomer having two or more identical or different carbon-carbon double bonds, with the above-mentioned alkyl (meth)acrylate, a polar functional group-containing monomer described later, or other monomers described later.

[0016] Examples of the functional group-containing unsaturated compounds include those selected according to the functional group in the carbon-carbon double bond-less (meth)acrylic polymer, and are similar to the polar functional group-containing monomers described later. When the functional group in the above carbon-carbon double bond-less (meth)acrylic polymer is a carboxyl group, for example, epoxy group-containing monomers or isocyanate group-containing monomers can be used. When the functional group in the above carbon-carbon double bond-less (meth)acrylic polymer is a hydroxyl group, for example, an isocyanate group-containing monomer can be used. When the functional group in the above carbon-carbon double bond-less (meth)acrylic polymer is an epoxy group, for example, carboxyl group-containing monomers or amide group-containing monomers such as acrylamide can be used. When the functional group in the above carbon-carbon double bond-less (meth)acrylic polymer is an amino group, for example, an epoxy group-containing monomer can be used. Furthermore, specific examples of the functional group-containing unsaturated compounds include 2-methacryloyloxyethyl isocyanate (MOI), 2-acryloyloxyethyl isocyanate (AOI), and 1,1-(bisacryloyloxymethyl)ethyl isocyanate (BEI).

[0017] The preferred lower limit for the content of constituent units derived from the functional group-containing unsaturated compound in the above (meth)acrylic copolymer is 0.1% by mass, and the preferred upper limit is 25% by mass. When the content of constituent units derived from the functional group-containing unsaturated compound is 0.1% by mass or more, the adhesive composition of the present invention can be sufficiently cured, and the adhesive composition of the present invention has superior peeling performance. When the content of constituent units derived from the functional group-containing unsaturated compound is 25% by mass or less, the adhesive composition of the present invention can maintain appropriate flexibility even after curing, and can be peeled more easily from uneven surfaces while suppressing the generation of adhesive residue. The more preferred lower limit for the content of constituent units derived from the functional group-containing unsaturated compound is 0.5% by mass, and the more preferred upper limit is 20% by mass.

[0018] Preferably, the (meth)acrylic copolymer further contains structural units derived from a polar functional group-containing monomer. By including structural units derived from a polar functional group-containing monomer in the (meth)acrylic copolymer, the cohesive force of the adhesive composition of the present invention becomes greater, allowing for easier peeling from uneven surfaces while suppressing the generation of adhesive residue. Furthermore, if the adhesive composition of the present invention contains a crosslinking agent described later, the adhesive strength of the adhesive composition of the present invention can be reduced by reacting the functional groups derived from the structural units derived from the polar functional group-containing monomer with the crosslinking agent during peeling, such as by irradiation with light or heating, resulting in an adhesive composition of the present invention with superior peeling performance. Furthermore, if the adhesive composition of the present invention contains a crosslinking agent described later, the adhesive strength of the adhesive composition of this embodiment is appropriately adjusted by the reaction of the polar functional groups derived from the structural units derived from the monomer having the polar functional group with the crosslinking agent, and as a result, the adhesive composition of this embodiment can be easily peeled from the adherend without leaving any adhesive residue during peeling.

[0019] Examples of constituent units derived from the above polar functional group-containing monomers include constituent units derived from carboxyl group-containing monomers, constituent units derived from hydroxyl group-containing monomers, constituent units derived from epoxy group-containing monomers, constituent units derived from isocyanate group-containing monomers, and constituent units derived from amino group-containing monomers. In particular, from the viewpoint of further improving the cohesive force of the adhesive composition, it is preferable that the (meth)acrylic copolymer contains at least one selected from the group consisting of constituent units derived from carboxyl group-containing monomers and constituent units derived from hydroxyl group-containing monomers. Furthermore, the constituent units derived from the above polar functional group-containing monomers may be included individually or in combination of two or more types.

[0020] Examples of the above-mentioned carboxyl group-containing monomers include acrylic acid and methacrylic acid. Examples of the hydroxyl group-containing monomers mentioned above include hydroxyethyl acrylate and hydroxyethyl methacrylate. Examples of the epoxy group-containing monomers mentioned above include glycidyl acrylate and glycidyl methacrylate. Examples of the above-mentioned isocyanate group-containing monomers include isocyanate ethyl acrylate and isocyanate ethyl methacrylate. Examples of the above-mentioned amino group-containing monomers include aminoethyl acrylate and aminoethyl methacrylate.

[0021] The preferred lower limit for the total content of constituent units derived from the carboxyl group-containing monomer in the (meth)acrylic copolymer is 0.01% by mass, and the preferred upper limit is 3.0% by mass. When the total content of constituent units derived from the carboxyl group-containing monomer is 0.01% by mass or more, the cohesive force of the adhesive composition of the present invention becomes greater, and it can be peeled off more easily from uneven surfaces while suppressing the generation of adhesive residue. Furthermore, when the adhesive composition of the present invention contains a crosslinking agent as described later, the adhesive strength of the adhesive composition of the present invention can be reduced by reacting the functional groups derived from the constituent units derived from the carboxyl group-containing monomer with the crosslinking agent during peeling, such as by irradiation with light or heating, and the adhesive composition of the present invention becomes superior in peeling performance. Furthermore, when the adhesive composition of the present invention contains a crosslinking agent as described later, the adhesive strength of the adhesive composition of this embodiment is appropriately adjusted by the reaction of the polar functional groups derived from the constituent units derived from the carboxyl group-containing monomer with the crosslinking agent, and as a result, the adhesive composition of this embodiment can be easily peeled off from the adherend without leaving any adhesive residue. By having a total content of 30% by mass or less of the constituent units derived from the above-mentioned carboxyl group-containing monomer, the adhesive composition of the present invention does not become too hard, has superior embedding properties for uneven surfaces, and possesses sufficient initial adhesive strength. A more preferable lower limit for the total content of the constituent units derived from the above-mentioned carboxyl group-containing monomer is 0.1% by mass, a more preferable upper limit is 2.0% by mass, an even more preferable lower limit is 0.5% by mass, and an even more preferable upper limit is 1.0% by mass. In the case where a carboxyl group-containing monomer is reacted with the above-mentioned functional group-containing unsaturated compound, the content ratio of the constituent units derived from the carboxyl group-containing monomer shall be the total content ratio of the constituent units derived from the carboxyl group-containing monomer used as the constituent unit monomer of the above-mentioned carbon-carbon double bond-less (meth)acrylic polymer and the constituent units derived from the carboxyl group-containing monomer reacted with the above-mentioned functional group-containing unsaturated compound.

[0022] The preferred lower limit for the total content of constituent units derived from the hydroxyl group-containing monomer in the above (meth)acrylic copolymer is 0.01% by mass, and the preferred upper limit is 30% by mass. When the total content of constituent units derived from the hydroxyl group-containing monomer is 0.01% by mass or more, the cohesive force of the adhesive composition of the present invention becomes greater, and peeling becomes easier while suppressing the generation of adhesive residue from uneven surfaces. Furthermore, when the adhesive composition of the present invention contains a crosslinking agent as described later, the adhesive strength of the adhesive composition of the present invention can be reduced by reacting the functional groups derived from the constituent units derived from the hydroxyl group-containing monomer with the crosslinking agent during peeling, such as by irradiation with light or heating, and the adhesive composition of the present invention becomes superior in peeling performance. Furthermore, when the adhesive composition of the present invention contains a crosslinking agent as described later, the adhesive strength of the adhesive composition of this embodiment is appropriately adjusted by the reaction of the polar functional groups derived from the constituent units derived from the hydroxyl group-containing monomer with the crosslinking agent, and as a result, the adhesive composition of this embodiment can be easily peeled off from the adherend without leaving any adhesive residue during peeling. By having a total content of 30% by mass or less of the constituent units derived from the above-mentioned hydroxyl group-containing monomer, the adhesive composition of the present invention does not become too hard, has superior embedding properties for uneven surfaces, and possesses sufficient initial adhesive strength. A more preferable lower limit for the total content of constituent units derived from the above-mentioned hydroxyl group-containing monomer is 1.0% by mass, a more preferable upper limit is 28% by mass, an even more preferable lower limit is 5.0% by mass, an even more preferable upper limit is 25% by mass, an even more preferable lower limit is 10% by mass, and an even more preferable upper limit is 20% by mass. Furthermore, in the case where a hydroxyl group-containing monomer is reacted with the above-mentioned functional group-containing unsaturated compound, the content ratio of constituent units derived from the above-mentioned hydroxyl group-containing monomer shall be the total content ratio of constituent units derived from the hydroxyl group-containing monomer used as the constituent unit monomer of the above-mentioned carbon-carbon double bond-less (meth)acrylic polymer and constituent units derived from the hydroxyl group-containing monomer reacted with the above-mentioned functional group-containing unsaturated compound.

[0023] The preferred lower limit for the total content of constituent units derived from the polar functional group-containing monomer in the above (meth)acrylic copolymer is 0.01% by mass, and the preferred upper limit is 30% by mass. When the total content of constituent units derived from the polar functional group-containing monomer is 0.01% by mass or more, the cohesive force of the adhesive composition of the present invention becomes greater, and peeling becomes easier while suppressing the generation of adhesive residue from uneven surfaces. Furthermore, when the adhesive composition of the present invention contains a crosslinking agent as described later, the adhesive strength of the adhesive composition of the present invention can be reduced by reacting the functional groups derived from the constituent units derived from the polar functional group-containing monomer with the crosslinking agent during peeling, such as by irradiation with light or heating, and the adhesive composition of the present invention becomes superior in peeling performance. Furthermore, when the adhesive composition of the present invention contains a crosslinking agent as described later, the adhesive strength of the adhesive composition of this embodiment is appropriately adjusted by the reaction of the polar functional groups derived from the constituent units derived from the polar functional group-containing monomer with the crosslinking agent, and as a result, the adhesive composition of this embodiment becomes easier to peel off from the adherend without leaving any adhesive residue during peeling. By having a total content of 30% by mass or less of the constituent units derived from the above polar functional group-containing monomers, the adhesive composition of the present invention does not become too hard, has superior embedding properties for uneven surfaces, and possesses sufficient initial adhesive strength. A more preferable lower limit for the total content of constituent units derived from the above polar functional group-containing monomers is 0.1% by mass, a more preferable upper limit is 28% by mass, an even more preferable lower limit is 1.0% by mass, and an even more preferable upper limit is 25% by mass. In the case where a polar functional group-containing monomer is used as the functional group-containing unsaturated compound, the total content ratio of constituent units derived from the polar functional group-containing monomer shall be the total content ratio of constituent units derived from the polar functional group-containing monomer used as the constituent unit monomer of the carbon-carbon double bond-less (meth)acrylic polymer and constituent units derived from the polar functional group-containing monomer reacted with the functional group-containing unsaturated compound.

[0024] The above (meth)acrylic copolymer may contain structural units derived from monomers other than the above C6 alkyl (meth)acrylate and the above polar functional group-containing monomer.

[0025] Examples of other monomers mentioned above include alkyl (meth)acrylates other than the C6 alkyl (meth)acrylates described above. Examples of alkyl(meth)acrylates other than the C6 alkyl(meth)acrylates listed above include methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, n-butyl(meth)acrylate, tert-butyl(meth)acrylate, n-heptyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, n-nonyl(meth)acrylate, isononyl(meth)acrylate, and decyl(meth)acrylate. Examples include isodecyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, esters of 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)-1-octanol with (meth)acrylic acid, esters of (meth)acrylic acid with an alcohol having 1 or 2 methyl groups in a linear main chain and a total of 18 carbon atoms, behenyl (meth)acrylate, arachidyl (meth)acrylate, and the like. These alkyl (meth)acrylates may be used individually or in combination of two or more types.

[0026] From the viewpoint of achieving both excellent embedding properties for uneven surfaces and excellent peeling performance of the adhesive composition of the present invention, and suppressing odors generated from the adhesive composition of the present invention, it is preferable that the (meth)acrylic copolymer does not have any constituent units derived from alkyl (meth)acrylate other than the C6 alkyl (meth)acrylate.

[0027] Other monomers include, for example, benzyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and polypropylene glycol mono(meth)acrylate. Furthermore, other monomers that can be used include, for example, vinyl carboxylates such as vinyl acetate, and various monomers commonly used in (meth)acrylic polymers such as styrene. These other monomers may be used individually or in combination of two or more.

[0028] Methods for producing the above-mentioned (meth)acrylic copolymer include, for example, a method in which a monomer mixture containing the above-mentioned C6 alkyl (meth)acrylate and the above-mentioned polar functional group-containing monomer is copolymerized by radical reaction in the presence of a polymerization initiator, and then the obtained carbon-carbon double bond-less (meth)acrylic polymer is reacted with a functional group-containing unsaturated compound. Conventional known methods can be used to carry out a radical reaction of the above monomer mixture, i.e., polymerization methods, such as solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, and bulk polymerization.

[0029] Examples of polymerization initiators used to produce the above-mentioned (meth)acrylic copolymer include organic peroxides and azo compounds. Examples of the above-mentioned organic peroxides include 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, and t-butylperoxylaurate. Examples of the above-mentioned azo compounds include azobisisobutyronitrile and azobiscyclohexanecarbonitride. These polymerization initiators may be used individually or in combination of two or more. Furthermore, if the radical reaction method is living radical polymerization, examples of polymerization initiators used to produce the (meth)acrylic copolymer include organic tellurium polymerization initiators. The organic tellurium polymerization initiator is not particularly limited as long as it is commonly used in living radical polymerization, and examples include organic tellurium compounds and organic telluride compounds. In addition to the organic tellurium polymerization initiator, the azo compound may also be used as a polymerization initiator to produce the (meth)acrylic copolymer in order to accelerate the polymerization rate, even in living radical polymerization.

[0030] The preferred lower limit for the carbon-carbon double bond equivalent of the above (meth)acrylic copolymer is 0.05 meq / g. A carbon-carbon double bond equivalent of 0.05 meq / g or higher in the above (meth)acrylic copolymer results in superior peeling performance of the adhesive composition of the present invention. A more preferred lower limit for the carbon-carbon double bond equivalent of the above (meth)acrylic copolymer is 0.06 meq / g, and an even more preferred lower limit is 0.075 meq / g. The preferred upper limit for the carbon-carbon double bond equivalent of the above (meth)acrylic copolymer is 3.5 meq / g. By having a carbon-carbon double bond equivalent of 3.5 meq / g or less, the adhesive composition of the present invention can maintain appropriate flexibility even after curing, and can be peeled off more easily from uneven surfaces while suppressing the generation of adhesive residue. The more preferred upper limit for the carbon-carbon double bond equivalent of the above (meth)acrylic copolymer is 2.0 meq / g. In this specification, "carbon-carbon double bond equivalent of (meth)acrylic copolymer" refers to the milliequivalent (meq / g) of carbon-carbon double bonds per gram of (meth)acrylic copolymer.

[0031] The preferred upper limit of the acid value of the above (meth)acrylic copolymer is 10 mg KOH / g. When the acid value of the above (meth)acrylic copolymer is 10 mg KOH / g or less, the adhesive composition of the present invention does not become too hard, has superior embedding properties for uneven surfaces, and has sufficient initial adhesive strength. A more preferred upper limit of the acid value of the above (meth)acrylic copolymer is 9.0 mg KOH / g, an even more preferred upper limit is 8.0 mg KOH / g, and an even more preferred upper limit is 7.0 mg KOH / g. Furthermore, the lower limit of the acid value of the (meth)acrylic copolymer is not particularly limited and may be 0 mg KOH / g. The acid value is an indicator that represents the content of carboxyl groups in a given amount of sample. The hydroxyl value of the (meth)acrylic copolymer is the number of mg of potassium hydroxide required to neutralize the acid contained in 1 g of the (meth)acrylic copolymer, and can be calculated by measuring it based on the potentiometric titration method specified in JIS K 0070:1992.

[0032] The preferred lower limit of the hydroxyl value of the (meth)acrylic copolymer is 5.0 mgKOH / g, and the preferred upper limit is 100 mgKOH / g. A hydroxyl value of 5.0 mgKOH / g or higher for the (meth)acrylic copolymer increases the cohesive force of the adhesive composition of the present invention, allowing for easy peeling from uneven surfaces while suppressing the generation of adhesive residue. Furthermore, if the adhesive composition of the present invention contains a crosslinking agent described later, the adhesive strength of the adhesive composition can be reduced by reacting the functional groups derived from the constituent units of the polar functional group-containing monomer with the crosslinking agent during peeling, such as by light irradiation or heating, resulting in superior peeling performance. Additionally, if the adhesive composition of the present invention contains a crosslinking agent described later, the adhesive strength of the adhesive composition of this embodiment is appropriately adjusted by the reaction of the polar functional groups derived from the constituent units of the polar functional group-containing monomer with the crosslinking agent, resulting in easier peeling of the adhesive composition from the adherend without leaving any residue. By having a hydroxyl value of 100 mgKOH / g or less for the (meth)acrylic copolymer, the adhesive composition of the present invention does not become too hard, has superior embedding properties for uneven surfaces, and possesses sufficient initial tackiness. A more preferred lower limit for the hydroxyl value of the (meth)acrylic copolymer is 7.0 mgKOH / g, a more preferred upper limit is 95 mgKOH / g, an even more preferred lower limit is 9.0 mgKOH / g, and an even more preferred upper limit is 90 mgKOH / g. The hydroxyl value is an index that represents the amount of hydroxyl groups in a given amount of sample. The hydroxyl value of the (meth)acrylic copolymer is the number of milligrams of potassium hydroxide required to neutralize the acetic acid bonded to the hydroxyl groups after acetylating 1 g of the (meth)acrylic copolymer by neutralization titration. This can be calculated by measuring it based on the potentiometric titration method specified in JIS K 0070:1992.

[0033] The preferred lower limit for the weight-average molecular weight (Mw) of the above (meth)acrylic copolymer is 200,000, and the preferred upper limit is 2,000,000. A weight-average molecular weight (Mw) of 200,000 or more ensures that the adhesive composition of the present invention has sufficient initial tackiness. A weight-average molecular weight (Mw) of 2,000,000 or less ensures that the adhesive composition of the present invention does not become too hard, has superior embedding properties for uneven surfaces, and possesses sufficient initial tackiness. A more preferred lower limit for the weight-average molecular weight (Mw) of the above (meth)acrylic copolymer is 250,000, a more preferred upper limit is 1,850,000, an even more preferred lower limit is 300,000, an even more preferred upper limit is 1,800,000, an even more preferred upper limit is 1,500,000, and a particularly preferred upper limit is 1,000,000. In this specification, the weight-average molecular weight of the (meth)acrylic copolymer is the weight-average molecular weight on a standard polystyrene basis calculated by GPC (Gel Permeation Chromatography). Specifically, for example, it can be measured using a Waters 2690 Separations Module as the measuring instrument, a Showa Denko GPC KF-806L as the column, and ethyl acetate as the solvent, with a sample flow rate of 1 mL / min and a column temperature of 40°C.

[0034] The glass transition temperature (Tg) of the (meth)acrylic copolymer is not particularly limited, but a preferred upper limit is -20°C. A glass transition temperature (Tg) of the (meth)acrylic copolymer of -20°C or lower improves the conformability of the adhesive layer containing the adhesive composition of the present invention to uneven surfaces, resulting in particularly higher adhesion to rough surfaces. A more preferred upper limit for the glass transition temperature (Tg) of the (meth)acrylic copolymer is -30°C, an even more preferred upper limit is -40°C, and an even more preferred upper limit is -50°C. Furthermore, the lower limit of the glass transition temperature (Tg) of the (meth)acrylic copolymer is not particularly limited and is usually -90°C or higher, but from the viewpoint of preventing adhesive residue on uneven surfaces, a preferred lower limit is -80°C. The glass transition temperature (Tg) of the above (meth)acrylic copolymer can be determined, for example, by differential scanning calorimetry.

[0035] The adhesive composition of the present invention preferably further contains at least one polymerization initiator selected from the group consisting of photopolymerization initiators and thermal polymerization initiators. The adhesive composition of the present invention contains at least one polymerization initiator selected from the group consisting of photopolymerization initiators and thermal polymerization initiators. This reaction between the polymerization initiator and the carbon-carbon double bonds in the side chains of the (meth)acrylic copolymer makes the adhesive composition of the present invention more prone to curing, thus reducing its adhesive strength. As a result, the adhesive composition of the present invention exhibits superior peelability. In particular, from the viewpoint of suppressing enhanced adhesion and outgassing at high temperatures, it is preferable that the adhesive composition of the present invention contains a photopolymerization initiator.

[0036] Examples of the above-mentioned photopolymerization initiators include those that are activated by irradiation with light of a wavelength of 250 to 800 nm. Examples of such photopolymerization initiators include acetophenone derivative compounds such as methoxyacetophenone and 2,2-dimethoxy-2-phenylacetophenone, benzoin ether compounds such as benzoin propyl ether and benzoin isobutyl ether, ketal derivative compounds such as benzyldimethyl ketal and acetophenone diethyl ketal, phosphine oxide derivative compounds such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(η5-cyclopentadienyl) titanocene derivative compounds, benzophenone, Michler ketone, chlorothioxanthone, todecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, α-hydroxycyclohexylphenyl ketone, 2-hydroxymethylphenylpropane, and 2-benzyl-2-(dimethylamino)-4'-morpholinobylophenone, which are photoradical polymerization initiators. These photopolymerization initiators may be used individually or in combination of two or more.

[0037] Examples of the above-mentioned thermal polymerization initiators include those that decompose upon heat and generate active radicals that initiate polymerization curing. Examples include dicumyl peroxide, di-t-butyl peroxide, t-butyl peroxybenzoyl, t-butyl hydroperoxide, benzoyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramentane hydroperoxide, di-t-butyl peroxide, and t-butyl peroxy-2-ethylhexanoate. These thermal polymerization initiators may be used individually or in combination of two or more.

[0038] A preferred lower limit for the content of the polymerization initiator per 100 parts by mass of the (meth)acrylic copolymer is 0.1 parts by mass. A content of 0.1 parts by mass or more of the polymerization initiator allows the adhesive composition of the present invention to cure sufficiently, resulting in superior peel performance. A more preferred lower limit for the content of the polymerization initiator is 0.5 parts by mass, an even more preferred lower limit is 0.8 parts by mass, and an even more preferred lower limit is 1.0 part by mass. Furthermore, while there is no particular upper limit to the content of the polymerization initiator, from the viewpoint of appearance defects caused by the precipitation of the polymerization initiator, a preferred upper limit for the content of the polymerization initiator per 100 parts by mass of the (meth)acrylic copolymer is 20 parts by mass. A more preferred upper limit is 15 parts by mass, an even more preferred upper limit is 10 parts by mass, and an even more preferred lower limit is 5.0 parts by mass.

[0039] The adhesive composition of the present invention preferably further contains an inorganic filler. The presence of an inorganic filler in the adhesive composition of the present invention increases its cohesive force. Therefore, even when additives with different polarities are mixed with the (meth)acrylic copolymer, separation does not occur, and the adhesive composition of the present invention can be made more uniform. Furthermore, the tensile strength of the adhesive composition of the present invention is significantly improved, so even after chemical treatment or high-temperature treatment, the adhesive composition does not break due to stress during peeling, and peeling is easier while suppressing the generation of adhesive residue. Moreover, peeling is easier while suppressing the generation of adhesive residue from uneven surfaces, resulting in superior peeling performance.

[0040] Examples of the inorganic fillers mentioned above include silica nanofillers such as fumed silica, fused silica, and colloidal silica, as well as alumina nanofillers, zirconia fillers, carbon nanofillers, glass fillers, titania fillers, and zinc oxide fillers. Among these, fumed silica nanoparticles and fused silica nanoparticles are preferred, and fumed silica nanoparticles are more preferred, because they allow for easy adjustment of the amount of hydroxyl groups on the surface, easy control of the moisture content, and a sufficiently small primary particle size, making it easier to adjust the average particle size of the inorganic fillers described later within an appropriate range.

[0041] The preferred lower limit for the average particle size of the inorganic filler is 0.05 μm, and the preferred upper limit is 3 μm. By having the average particle size of the inorganic filler within the above range, the inorganic filler is finely dispersed in the adhesive composition of the present invention, thereby making the adhesive composition more uniform. The average particle size can be determined, for example, by observing 50 arbitrary inorganic fillers with an electron microscope or optical microscope and calculating the average particle size of each inorganic filler, or by performing a laser diffraction particle size distribution measurement.

[0042] The preferred lower limit for the content of the inorganic filler per 100 parts by mass of the (meth)acrylic copolymer is 1.0 part by mass, and the preferred upper limit is 40 parts by mass. When the inorganic filler content is within the above range, the cohesive force of the adhesive composition of the present invention becomes greater, and it can be peeled off more easily from uneven surfaces while suppressing the generation of adhesive residue. The more preferred lower limit for the inorganic filler content is 5.0 parts by mass, and the more preferred upper limit is 20 parts by mass.

[0043] The adhesive composition of the present invention preferably further contains a polyfunctional oligomer or a polyfunctional monomer. The inclusion of the above-mentioned polyfunctional oligomer or polyfunctional monomer in the adhesive composition of the present invention allows for efficient three-dimensional network formation of the adhesive composition by light irradiation or heat load, resulting in superior release properties of the adhesive composition of the present invention. In this specification, "polyfunctional oligomer or polyfunctional monomer" means a compound having two or more functional groups having carbon-carbon unsaturated bonds in its molecule and having a weight-average molecular weight of 50,000 or less. Furthermore, in this specification, the carbon-carbon unsaturated bonds of the "functional groups having carbon-carbon unsaturated bonds" in the polyfunctional oligomer or polyfunctional monomer do not include carbon-carbon double bonds that constitute an aromatic ring. Furthermore, the weight-average molecular weight of the above-mentioned polyfunctional oligomer or polyfunctional monomer can be determined using the GPC measurement method, similar to the weight-average molecular weight of the (meth)acrylic copolymer described above.

[0044] Examples of functional groups having the above-mentioned carbon-carbon unsaturated bond include vinyl groups, (meth)acryloyl groups, allyl groups, and maleimide groups. Among these, vinyl groups are preferred from the viewpoint of their rapid reaction rate with light and heat.

[0045] Examples of the polyfunctional oligomers or polyfunctional monomers mentioned above include (meth)acrylate monomers having a functional group having a carbon-carbon unsaturated bond, (meth)acrylic oligomers copolymerized with the (meth)acrylate monomer having a functional group having a carbon-carbon unsaturated bond (excluding those having a structural unit derived from n-hexyl (meth)acrylate and containing a carbon-carbon double bond in the side chain), as well as silicone compounds having a functional group having a carbon-carbon unsaturated bond, and fluorine compounds having a functional group having a carbon-carbon unsaturated bond.

[0046] The adhesive composition of the present invention contains a (meth)acrylate monomer having a functional group having a carbon-carbon unsaturated bond, and a (meth)acrylic oligomer copolymerized with the (meth)acrylate monomer having a functional group having a carbon-carbon unsaturated bond. As a result, the adhesive composition of the present invention exhibits improved photocurability and thermocurability, and superior peelability.

[0047] In the (meth)acrylate monomer having the above-mentioned carbon-carbon unsaturated bond functional group, and the (meth)acrylic oligomer copolymerized with the above-mentioned carbon-carbon unsaturated bond functional group, the preferred lower limit of the number of carbon-carbon unsaturated bond functional groups is 2 and the preferred upper limit is 20, from the viewpoint of making the three-dimensional networking of the adhesive layer more efficient by heating or light irradiation.

[0048] Examples of (meth)acrylic oligomers copolymerized with the above-mentioned (meth)acrylate monomers having a functional group having a carbon-carbon unsaturated bond, and (meth)acrylic oligomers copolymerized with the above-mentioned (meth)acrylate monomers having a functional group having a carbon-carbon unsaturated bond, include trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate 1,4-butyl Examples include oligoester acrylates such as ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol diacrylate, EBECRYL524, EBECRYL436 (all manufactured by Daicel Ornex), urethane acrylate monomers such as UN-5500, UN-5590 (both manufactured by Negami Kogyo Co., Ltd.), UA-160TM, UA-122P (both manufactured by Shin Nakamura Chemical Co., Ltd.), and (meth)acrylic oligomers copolymerized with these (meth)acrylate monomers. These (meth)acrylate monomers having carbon-carbon unsaturated bonds, and (meth)acrylic oligomers copolymerized with (meth)acrylates having carbon-carbon unsaturated bonds, may be used individually or in combination of two or more types.

[0049] The adhesive composition of the present invention contains a silicone compound having a functional group having a carbon-carbon unsaturated bond and a fluorine compound having a functional group having a carbon-carbon unsaturated bond. Because the silicone compound or fluorine compound bleeds out at the interface of the adherend, the adhesive can be peeled off more easily while suppressing the generation of adhesive residue. The adhesive composition of the present invention may contain both the silicone compound having a functional group having a carbon-carbon unsaturated bond and the fluorine compound having a functional group having a carbon-carbon unsaturated bond.

[0050] The silicone compound having a carbon-carbon unsaturated bond or the fluorine compound having a carbon-carbon unsaturated bond is preferably further crosslinkable with the (meth)acrylic copolymer. Having a functional group that can crosslink with the (meth)acrylic copolymer allows the silicone compound having a carbon-carbon unsaturated bond or the fluorine compound having a carbon-carbon unsaturated bond to react more efficiently with the (meth)acrylic copolymer through the use of a crosslinking agent or light irradiation. This makes it easier for the compound to be incorporated into the (meth)acrylic copolymer, further suppressing contamination of the adherend by the silicone compound or fluorine compound.

[0051] The functional groups that can be crosslinked with the above (meth)acrylic copolymer are appropriately selected from the functional groups contained in the above (meth)acrylic copolymer, but examples include carboxyl groups, hydroxyl groups, amide groups, isocyanate groups, epoxy groups, etc.

[0052] In the silicone compound having the above-mentioned carbon-carbon unsaturated bond functional group or the fluorine compound having the above-mentioned carbon-carbon unsaturated bond functional group, the preferred lower limit of the total number of the carbon-carbon unsaturated bond functional group and the functional group that can crosslink with the (meth)acrylic copolymer is 2, and the preferred upper limit is 12. When the total number of the carbon-carbon unsaturated bond functional group and the functional group that can crosslink with the (meth)acrylic copolymer is 2 or more, contamination by the adhesion of the silicone compound or fluorine compound to the adherend is further suppressed. When the total number of the carbon-carbon unsaturated bond functional group and the functional group that can crosslink with the (meth)acrylic copolymer is 12 or less, the three-dimensional networking of the adhesive composition of the present invention by light irradiation or heating is made more efficient. A more preferred upper limit of the total number of the carbon-carbon unsaturated bond functional group and the functional group that can crosslink with the (meth)acrylic copolymer is 4, and the most preferred total number of the carbon-carbon unsaturated bond functional group and the functional group that can crosslink with the (meth)acrylic copolymer is 2.

[0053] Examples of silicone compounds having the above-mentioned carbon-carbon unsaturated bond functional group include silicone (meth)acrylate monomers, silicone di(meth)acrylate monomers, and (meth)acrylic oligomers copolymerized therefrom (excluding those having n-hexyl(meth)acrylate as a constituent unit and containing a carbon-carbon double bond in the side chain). Commercially available silicone compounds having the above-mentioned carbon-carbon unsaturated bond functional group include, for example, silicone compounds having a methacryloyl group such as X-22-164, X-22-164AS, X-22-164A, X-22-164B, X-22-164C, X-22-164E, X-22-174DX, X-22-2426, X-22-2475 (all manufactured by Shin-Etsu Chemical Co., Ltd.), MAC-SQ TM-100, MACSQSI-20, MAC-SQ HDM (all manufactured by Toagosei Co., Ltd.), and silicone compounds having an acryloyl group such as EBECRYL350, EBECRYL1360 (both manufactured by Daicel Ornex Co., Ltd.), AC-SQ TA-100, AC-SQ SI-20 (both manufactured by Toagosei Co., Ltd.).

[0054] Examples of fluorine compounds having the carbon-carbon unsaturated bond mentioned above include (meth)acrylic oligomers containing constituent units derived from fluoro(meth)acrylate monomers (excluding those containing n-hexyl(meth)acrylate as a constituent unit and having a carbon-carbon double bond in the side chain). Examples of the above-mentioned fluoro(meth)acrylates include methyl-2-fluoroacrylate and 2-(perfluorobutyl)ethyl acrylate.

[0055] The preferred lower limit for the content of the polyfunctional oligomer or polyfunctional monomer per 100 parts by mass of the (meth)acrylic copolymer is 1.0 part by mass, and the preferred upper limit is 50 parts by mass. By having the content of the polyfunctional oligomer or polyfunctional monomer within the above range, the adhesive composition of the present invention will have superior peeling performance. A more preferred lower limit for the content of the polyfunctional oligomer or polyfunctional monomer is 2.0 parts by mass, a more preferred upper limit is 40 parts by mass, an even more preferred lower limit is 5.0 parts by mass, and an even more preferred upper limit is 20 parts by mass.

[0056] The adhesive composition of the present invention preferably further contains a gas generating agent. Because the adhesive composition of the present invention contains the gas generating agent, gas can be generated on the adhesive surface by light irradiation or heating, thereby improving the peeling performance of the adhesive composition of the present invention.

[0057] The gas generating agent described above is not particularly limited, but gas generating agents that generate gas by light (e.g., ultraviolet light, laser light, etc.), heat, electromagnetic waves, or electron beams are preferred. In particular, from the viewpoint of suppressing enhanced adhesion and outgassing of the adhesive composition of the present invention at high temperatures, gas generating agents that generate gas by light are preferred. The gas generating agent described above is not particularly limited, but for example, azo compounds, azide compounds, carboxylic acid compounds, tetrazole compounds, etc., are suitably used.

[0058] Examples of the azo compounds used as the gas generating agent include 2,2'-azobis-(N-butyl-2-methylpropionamide), 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}, 2,2'-azobis{2-methyl-N-[2-(1-hydroxybutyl)]propionamide}, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], and 2-azobis[N-(2-propenyl)-2-methylpropionamide]. [Propionamide], 2,2'-Azobis(N-butyl-2-methylpropionamide), 2,2'-Azobis(N-cyclohexyl-2-methylpropionamide), 2,2'-Azobis[2-(5-methyl-2-imidazoyl-2-yl)propane]dihydrochloride, 2,2'-Azobis[2-(2-imidazoyl-2-yl)propane]dihydrochloride, 2,2'-Azobis[2-(2-imidazoyl-2-yl)propane]disulfate dihydrolate, 2,2'-Azobis [2-(3,4,5,6-tetrahydropyrimidine-2-yl)propane]dihydrochloride, 2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazoylin-2-yl]propane}dihydrochloride, 2,2'-azobis[2-(2-imidazoylin-2-yl)propane], 2,2'-azobis(2-methylpropionamidin)hydrochloride, 2,2'-azobis(2-aminopropane)dihydrochloride, 2,2'-azobis[N-(2-carboxya Examples include [sil)-2-methyl-propionamidin], 2,2'-azobis{2-[N-(2-carboxyethyl)amidin]propane}, 2,2'-azobis(2-methylpropionamidooxime), dimethyl-2,2'-azobis(2-methylpropionate), dimethyl-2,2'-azobisisobutyrate, 4,4'-azobis(4-cyanic carbonic acid), 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2,4,4-trimethylpentane), etc.

[0059] Examples of azide compounds used as gas generating agents include polymers having an azide group, such as 3-azidomethyl-3-methyloxetane, terephthal azide, p-tert-butylbenz azide, and glycidyl azide polymers obtained by ring-opening polymerization of 3-azidomethyl-3-methyloxetane.

[0060] Examples of the carboxylic acid compounds used as the gas generating agent include phenylacetic acid, diphenylacetic acid, triphenylacetic acid, or their salts.

[0061] Examples of the tetrazole compounds used as gas generating agents include 1H-tetrazole, 5-phenyl-1H-tetrazole, 5,5-azobis-1H-tetrazole, or salts thereof.

[0062] The preferred lower limit for the content of the gas generating agent per 100 parts by mass of the (meth)acrylic copolymer is 5.0 parts by mass, and the preferred upper limit is 50 parts by mass. A content of 5.0 parts by mass or more of the gas generating agent allows for the generation of a gas capable of sufficiently peeling the adhesive composition of the present invention. A content of 50 parts by mass or less of the gas generating agent results in superior compatibility between the gas generating agent and other components in the adhesive composition of the present invention, resulting in the adhesive composition having sufficient initial tackiness. A more preferred lower limit for the content of the gas generating agent is 10 parts by mass, and a more preferred upper limit is 30 parts by mass.

[0063] The adhesive composition of the present invention preferably further contains a tackifier. The inclusion of a tackifier in the adhesive composition of the present invention results in sufficient initial tackiness.

[0064] Examples of the tackifiers mentioned above include rosin resins, rosin ester resins, hydrogenated rosin resins, hydrogenated rosin ester resins, terpene resins, terpene phenol resins, coumarone indene resins, alicyclic saturated hydrocarbon resins, C5 petroleum resins, C9 petroleum resins, and C5-C9 copolymer petroleum resins. These tackifiers may be used individually or in combination of two or more types.

[0065] Preferably, the tackifier described above includes a tackifier containing bio-derived carbon. By including a tackifier containing bio-derived carbon, the content of bio-derived carbon in the adhesive layer described later can be increased, and the environmental impact of the resulting adhesive tape can be further reduced. Examples of tackifiers containing the above-mentioned bio-derived carbon include KE-100, KE-359, KE-604, KR-140, A-75, and 803L (all manufactured by Arakawa Chemical Industries, Ltd.).

[0066] The preferred lower limit for the content of the tackifier per 100 parts by mass of the (meth)acrylic copolymer is 5.0 parts by mass, and the preferred upper limit is 60 parts by mass. A content of 5.0 parts by mass or more of the tackifier results in the adhesive composition of the present invention having sufficient initial tackiness. A content of 60 parts by mass or less of the tackifier results in the adhesive composition of the present invention not having excessively high tackiness, and thus having superior peeling performance. A more preferred lower limit for the content of the tackifier is 7.5 parts by mass, a more preferred upper limit is 30 parts by mass, and an even more preferred upper limit is 20 parts by mass.

[0067] When the (meth)acrylic copolymer contains structural units derived from the polar functional group-containing monomer, the adhesive composition of the present invention preferably contains a crosslinking agent. The presence of a crosslinking agent in the adhesive composition of the present invention causes a significant decrease in adhesive strength due to the reaction between the polar functional groups derived from the structural units of the polar functional group-containing monomer and the crosslinking agent. As a result, the adhesive composition of the present invention exhibits superior peelability. Furthermore, from the viewpoint of storage stability and other factors, the above-mentioned crosslinking agent may be incorporated into the adhesive composition of the present invention immediately before forming the adhesive layer.

[0068] Examples of the crosslinking agents mentioned above include isocyanate-based crosslinking agents, aziridine-based crosslinking agents, epoxy-based crosslinking agents, and metal chelate-based crosslinking agents. Among these, isocyanate-based crosslinking agents are preferred because they have a fast reaction rate and further enhance the cohesive force of the adhesive composition of the present invention.

[0069] The preferred lower limit for the content of the crosslinking agent per 100 parts by mass of the (meth)acrylic copolymer is 0.05 parts by mass, and the preferred upper limit is 10 parts by mass. By having the content of the crosslinking agent within the above range, the gel fraction of the adhesive layer containing the adhesive composition of the present invention is appropriately adjusted in the adhesive tape described later, resulting in sufficient initial adhesive strength. The more preferred lower limit for the content of the crosslinking agent is 0.1 parts by mass, the more preferred upper limit is 5.0 parts by mass, and the still more preferred upper limit is 2.0 parts by mass.

[0070] The adhesive composition of the present invention may further contain known additives such as plasticizers, surfactants, and waxes. These additives may be used individually or in combination of two or more.

[0071] Methods for producing the adhesive composition of the present invention include, for example, mixing the (meth)acrylic copolymer and, if necessary, the polymerization initiator, the inorganic filler, the polyfunctional oligomer or polyfunctional monomer, the gas generating agent, the crosslinking agent, the known additives, etc.

[0072] An adhesive tape having an adhesive layer formed using the adhesive composition of the present invention is also one of the present inventions. The adhesive tape of the present invention can achieve both excellent embedding ability for uneven surfaces and excellent peeling performance. The gel fraction of the adhesive layer and the bio-derived carbon content of the adhesive layer, as described later, can be adjusted to the values ​​described later by adjusting the types and content of each component constituting the adhesive composition of the present invention. A method for forming an adhesive layer using the adhesive composition of the present invention includes, for example, applying the adhesive composition of the present invention to a release film or the like, and then heating and drying the adhesive composition.

[0073] The thickness of the adhesive layer described above is not particularly limited, but a preferred lower limit is 5 μm and a preferred upper limit is 300 μm. By having the thickness of the adhesive layer within the above range, the adhesive layer is more flexible, and the adhesive tape of the present invention can achieve both better embedding ability against uneven surfaces and better peeling performance. A more preferred lower limit for the thickness of the adhesive layer is 20 μm, a more preferred upper limit is 200 μm, an even more preferred lower limit is 35 μm, an even more preferred upper limit is 150 μm, and an even more preferred upper limit is 100 μm.

[0074] The preferred lower limit for the bio-derived carbon content in the adhesive layer is 10%. A bio-derived carbon content of 10% or more in the adhesive layer makes the adhesive tape of the present invention superior in terms of conserving petroleum resources and reducing carbon dioxide emissions, thus further reducing the environmental burden. A more preferred lower limit for the bio-derived carbon content in the adhesive layer is 25%, and an even more preferred lower limit is 40%. Furthermore, there is no particular upper limit to the content of bio-derived carbon in the adhesive layer described above, and it may be 100%. Furthermore, while bio-derived carbon contains a certain percentage of the radioactive isotope C-14, petroleum-derived carbon contains almost no C-14. Therefore, the content of bio-derived carbon can be calculated by measuring the concentration of C-14 contained in the adhesive layer. Specifically, this can be measured in accordance with ASTM D6866-22, a standard widely used in the bioplastics industry.

[0075] The preferred lower limit for the gel fraction of the adhesive layer is 10% by mass, and the preferred upper limit is 90% by mass. A gel fraction of 10% by mass or more in the adhesive layer further improves the embedding ability of the adhesive tape of the present invention into uneven surfaces. A gel fraction of 90% by mass or less in the adhesive layer ensures that the adhesive tape of the present invention has sufficient initial adhesive strength. A more preferred lower limit for the gel fraction of the adhesive layer is 20% by mass, a more preferred upper limit is 80% by mass, an even more preferred lower limit is 30% by mass, an even more preferred upper limit is 70% by mass, and an even more preferred lower limit is 40% by mass. The gel fraction of the adhesive layer can be measured by the following method. From the obtained adhesive tape, W0 (g) of only the adhesive layer is extracted and immersed in 50 mL of ethyl acetate. The mixture is shaken in a shaker at 23°C and 200 rpm for 24 hours. After shaking, the ethyl acetate and the adhesive layer that has absorbed and swollen with ethyl acetate are separated using a metal mesh (mesh size #200, W1 (g)). The separated adhesive layer is dried at 110°C for 1 hour. The mass W2 (g) of the adhesive layer including the metal mesh after drying is measured, and the gel fraction (mass%) of the adhesive layer is measured using the following formula. Gel fraction (mass %) = 100 × (W2 - W1) / W0 (W0: initial mass of the adhesive layer, W1: initial mass of the metal mesh, W2: mass of the adhesive layer including the metal mesh after drying)

[0076] After heating at 150°C for 1 hour, or after emitting light of any wavelength within the range of 280 nm to 405 nm with an integrated light intensity of 1000 mJ / cm² 2 The preferred lower limit for the gel fraction of the adhesive layer after irradiation (hereinafter sometimes referred to as "gel fraction of the adhesive layer after curing") is 90% by mass. A gel fraction of 90% by mass or higher in the adhesive layer after curing results in superior peel performance for the adhesive tape of the present invention. A more preferred lower limit for the gel fraction of the adhesive layer after curing is 92% by mass, and an even more preferred lower limit is 95% by mass. Furthermore, the upper limit of the gel fraction after curing of the adhesive layer is not particularly limited and may be 100% by mass. Incidentally, the gel fraction of the adhesive layer after curing is heated at 150°C for 1 hour or irradiated with light having any wavelength within the range of 280 nm or more and 405 nm or less so that the integrated light amount becomes 1000 mJ / cm 2 or more, and after curing the adhesive layer, it can be measured by the same method as the gel fraction of the adhesive layer described above. Also, as a method of irradiating with light having any wavelength within the range of 280 nm or more and 405 nm or less so that the integrated light amount becomes 1000 mJ / cm 2 or more, for example, light having a wavelength of 405 nm and an illuminance of 100 mW / cm 2 is irradiated for 25 seconds so that the integrated light amount becomes 2500 mJ / cm 2 or the like can be mentioned.

[0077] The preferable upper limit of the shear storage modulus of the adhesive layer at 23°C is 1.2×10 5 Pa. When the shear storage modulus of the adhesive layer at 23°C is 1.2×10 5 Pa or less, the adhesive layer does not become too hard, and the adhesive tape of the present invention has excellent embedding property with respect to unevenness. The more preferable upper limit of the shear storage modulus of the adhesive layer at 23°C is 1.1×10 5 Pa, and the further preferable upper limit is 1.0×10 5 Pa. The lower limit of the shear storage modulus of the adhesive layer at 23°C is not particularly limited, but from the viewpoint that the adhesive tape of the present invention has sufficient initial adhesive force, the preferable lower limit is 0.1×10 5 Pa, and the more preferable lower limit is 0.3×10 5 Pa. Incidentally, the shear storage modulus of the adhesive layer at 23°C can be measured by performing dynamic viscoelasticity measurement under the conditions of a shear direction, a frequency of 10 Hz, a temperature rising rate of 10°C / min, and a temperature range from -50°C to 300°C using, for example, a viscoelastic spectrometer (manufactured by IT Measurement & Control Co., Ltd., "DVA-200") or the like. Furthermore, if the thickness of the adhesive layer is less than 200 μm, the adhesive layers are stacked to form a measuring adhesive layer with a thickness of 400 μm or more and 1 mm or less. The shear storage modulus of the obtained measuring adhesive layer is measured as described above.

[0078] After heating at 150°C for 1 hour, or after emitting light of any wavelength within the range of 280 nm to 405 nm with an integrated light intensity of 1000 mJ / cm² 2 The preferred lower limit of the tensile storage modulus at 23°C of the adhesive layer after irradiation (hereinafter sometimes referred to as "tensile storage modulus at 23°C after curing of the adhesive layer") is 1.0 × 10⁻⁶. 6 The tensile storage modulus at 23°C after curing of the adhesive layer is 1.0 × 10⁻⁶. 6 By having a Pa or higher, the adhesive tape of the present invention exhibits superior peel performance. A more preferable lower limit for the tensile storage modulus at 23°C after curing of the adhesive layer is 5.0 × 10⁻⁶. 6 Pa, a more preferable lower limit is 1.0 × 10⁻⁶ 7 It is Pa. Furthermore, there is no particular upper limit to the preferred tensile storage modulus at 23°C after curing of the adhesive layer, but 4.0 × 10 7 The upper limit is around Pa. The tensile storage modulus at 23°C after curing of the above adhesive layer is determined by heating at 150°C for 1 hour, or by emitting light of any wavelength within the range of 280 nm to 405 nm with an integrated light intensity of 1000 mJ / cm². 2 After curing the adhesive layer by irradiating it in the manner described above, dynamic viscoelasticity measurements can be performed using a viscoelastic spectrometer (IT Measurement Control Co., Ltd., "DVA-200") under the following conditions: tensile direction, frequency of 10 Hz, heating rate of 10°C / min, and temperature range from -5°C to 300°C. Alternatively, light of any wavelength within the range of 280 nm to 405 nm with an integrated light intensity of 1000 mJ / cm² can be used. 2 For example, an irradiation method that achieves the above results would use a wavelength of 405 nm and an illuminance of 100 mW / cm². 2 The integrated light intensity of the light is 2500 mJ / cm². 2Examples include irradiating for 25 seconds to achieve the desired result. Furthermore, if the thickness of the adhesive layer is less than 400 μm, the adhesive layers are stacked to form a measuring adhesive layer with a thickness of 400 μm or more and 1 mm or less. The tensile storage modulus of the obtained measuring adhesive layer is measured as described above.

[0079] When the adhesive tape of the present invention has a base material, the adhesive layer for measuring the shear storage modulus at 23°C and the tensile storage modulus at 23°C after curing of the adhesive layer is prepared by removing the base material from the adhesive tape and using only the adhesive layer to prepare the adhesive layer for measurement. The method for removing the base material is not particularly limited, as long as it avoids treatment with solvents, treatment involving chemical reactions, treatment at high temperatures, etc., in order to avoid deformation of the adhesive layer. Specific methods include separating the base material and adhesive layer by bonding the adhesive layers together, selecting an appropriate temperature and peeling speed, and then peeling them apart to remove the base material, or physically grinding the base material. Alternatively, the adhesive layer for measurement may be prepared using a sheet consisting only of the adhesive layer prepared separately.

[0080] The method for adjusting the gel fraction of the adhesive layer, the gel fraction of the adhesive layer after curing, the shear storage modulus of the adhesive layer at 23°C, and the tensile storage modulus of the adhesive layer at 23°C after curing to the above range is not particularly limited. Examples include adjusting the composition of the monomers constituting the (meth)acrylic copolymer, the weight-average molecular weight (Mw), carbon-carbon double bond equivalent, hydroxyl value, acid value, etc., of the (meth)acrylic copolymer.

[0081] The adhesive tape of the present invention may be a non-support tape without a base material, or it may be a support tape having a base material.

[0082] If the adhesive tape of the present invention is a support tape having a base material, it may be a single-sided adhesive tape having the adhesive layer on one side of the base material, or it may be a double-sided adhesive tape having the adhesive layer on both sides of the base material.

[0083] The above-mentioned substrate is not particularly limited, but it is preferably one that transmits or lets light through. Examples include sheets made of transparent resins such as acrylic, olefin, polycarbonate, vinyl chloride, ABS, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), nylon, urethane, polyamide, polyether, polyketone, and polyetheretherketone; sheets having a mesh structure; and sheets with holes.

[0084] From the viewpoint of increasing the overall bio-derived carbon content of the adhesive tape, it is preferable to use a bio-derived substrate. Examples of the above-mentioned bio-derived substrates include films and nonwoven fabrics containing plant-derived polyesters (PES) such as polyethylene terephthalate (PET), polyethylene furanoate (PEF), polylactic acid (PLA), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polybutylene succinate (PBS). Also included are films and nonwoven fabrics containing plant-derived polyethylene (PE), polypropylene (PP), polyurethane (PU), triacetylcellulose (TAC), cellulose, and polyamide (PA).

[0085] Furthermore, from the perspective of reducing environmental impact by decreasing the use of new petroleum resources and suppressing carbon dioxide emissions, base materials made from recycled resources may be used. Methods for recycling resources include, for example, recovering waste from packaging containers, home appliances, automobiles, construction materials, food, etc., or waste generated in the manufacturing process, and using the extracted materials again as raw materials by washing, decontamination, or decomposition by heating or fermentation. Examples of base materials made from recycled resources include films and nonwoven fabrics made from PET, PBT, PE, PP, PA, etc., using recovered plastics that have been re-resinated as raw materials. Alternatively, recovered waste may be burned and used as thermal energy for the manufacture of base materials and their raw materials, or the oils and fats contained in the recovered waste may be mixed with petroleum, fractionated, and refined to be used as raw materials.

[0086] The thickness of the above-mentioned substrate is not particularly limited, but a preferred lower limit is 12 μm and a preferred upper limit is 200 μm. By having the thickness of the above-mentioned substrate within the above range, it is possible to create an adhesive tape that exhibits high flexibility, allowing it to adhere closely to the shape of the substrate, while also having appropriate stiffness and excellent handling properties. A more preferred lower limit for the thickness of the above-mentioned substrate is 25 μm and a more preferred upper limit is 125 μm.

[0087] The method for manufacturing the adhesive tape of the present invention is not particularly limited and can be manufactured by conventionally known manufacturing methods. For example, in the case of double-sided adhesive tape, the following methods can be used. First, a solution of adhesive composition A is prepared by adding a solvent to a (meth)acrylic copolymer and, if necessary, a tackifier, crosslinking agent, etc. This solution of adhesive composition A is applied to the surface of the substrate, and the solvent in the solution is dried off to form an adhesive layer A. Next, a release film is placed on top of the formed adhesive layer A with its release treated surface facing the adhesive layer A. Next, a solution of adhesive composition B, prepared in the same manner as above, is applied to the release treatment surface of a release film separate from the above-mentioned release film, and the solvent in the solution is dried and removed to create a laminated film in which adhesive layer B is formed on the surface of the release film. The obtained laminated film is then placed on the back surface of a substrate on which adhesive layer A is formed, with adhesive layer B facing the back surface of the substrate, to create a laminate. Then, by pressing the laminate with a rubber roller or the like, a double-sided adhesive tape can be obtained in which adhesive layers formed using the adhesive composition are on both sides of the substrate, and the surface of the adhesive layer is covered with a release film.

[0088] Alternatively, two sets of laminated films may be prepared in the same manner, and these laminated films may be superimposed on each of the two sides of a substrate with the adhesive layer of the laminated film facing the substrate to create a laminate. This laminate may then be pressed with a rubber roller or the like to obtain a double-sided adhesive tape having adhesive layers on both sides of the substrate, with the surface of the adhesive layer covered with a release film.

[0089] A preferred lower limit for the 180° peel force of the adhesive tape of the present invention against SUS is 0.3 N / 25 mm. A 180° peel force of 0.3 N / 25 mm or higher for the adhesive tape of the present invention against SUS ensures sufficient initial adhesion. A more preferred lower limit for the 180° peel force of the adhesive tape of the present invention against SUS is 0.5 N / 25 mm, and an even more preferred lower limit is 1.0 N / 25 mm. Furthermore, while there is no particular upper limit to the 180° peel force of the adhesive tape of the present invention relative to SUS, a preferred upper limit is approximately 20 N / 25 mm from the viewpoint of the handling of the adhesive tape. The 180° peel strength of the adhesive tape of the present invention against SUS can be measured by a tensile test conducted in accordance with JIS Z0237, under the conditions of 23°C, a peeling speed of 300 mm / min, and a peeling angle of 180°.

[0090] After heating at 150°C for 1 hour, or after emitting light of any wavelength within the range of 280 nm to 405 nm with an integrated light intensity of 1000 mJ / cm²2 The preferred upper limit for the 180° peel force of the adhesive tape against SUS after irradiation (hereinafter sometimes referred to as "180° peel force of the adhesive tape against SUS after the adhesive layer has hardened") is 0.30 N / 25 mm. Having a 180° peel force of 0.30 N / 25 mm or less for the adhesive tape against SUS after the adhesive layer has hardened results in superior peel performance. A more preferred upper limit for the 180° peel force of the adhesive tape against SUS after the adhesive layer has hardened is 0.25 N / 25 mm, and an even more preferred upper limit is 0.20 N / 25 mm. Furthermore, while there is no particular limit to the 180° peel force on SUS after the adhesive layer of the above adhesive tape has hardened, it is preferable that it be greater than 0 N / 25 mm. Furthermore, the 180° peel strength of the adhesive tape on SUS after the adhesive layer has hardened is determined by heating the tape at 150°C for 1 hour before performing the tensile test, or by integrating light of any wavelength within the range of 280 nm to 405 nm with an integrated light intensity of 1000 mJ / cm². 2 The adhesive tape of the present invention can be cured by irradiating it in the manner described above, and then measured by performing a tensile test. Light with a wavelength within the range of 280 nm to 405 nm, with an integrated light intensity of 1000 mJ / cm². 2 For example, an irradiation method that achieves the above results would use a wavelength of 405 nm and an illuminance of 100 mW / cm². 2 The integrated light intensity of the light is 2500 mJ / cm². 2 Examples include irradiating for 25 seconds to achieve the desired result.

[0091] The method for adjusting the 180° peel force of the adhesive tape of the present invention to SUS, and the 180° peel force of the adhesive tape to SUS after the adhesive layer has hardened, to the above range is not particularly limited. For example, this could involve adjusting the composition of the monomers constituting the (meth)acrylic copolymer, or adjusting the weight-average molecular weight (Mw), carbon-carbon double bond equivalent, hydroxyl value, acid value, etc., of the (meth)acrylic copolymer.

[0092] The adhesive tape of the present invention has excellent embedding and peeling properties for uneven surfaces, and is therefore preferably used for temporary fixing of objects having uneven surfaces, and more preferably for temporary fixing of electronic equipment components. Specifically, it is even more preferably used for temporary fixing of semiconductor wafers in the manufacturing of electronic equipment components, and even more preferably used for temporary fixing of bump wafers having uneven surfaces.

[0093] Another method for processing a semiconductor wafer, comprising the steps of temporarily fixing the semiconductor wafer to a support using the adhesive tape of the present invention, and peeling off the adhesive tape after the adhesive layer has hardened by light or heat, is also part of the present invention. By using the adhesive tape of the present invention in the semiconductor wafer processing method of the present invention, the processing quality of electronic components manufactured can be further improved even when the semiconductor wafer has an uneven surface.

[0094] Examples of the above-mentioned support include glass, quartz, sapphire, copper plate, organic substrate, FR4 substrate, and silicon substrate. Among these, materials with excellent ultraviolet transmittance are preferred, with glass, quartz, and sapphire being preferred. Because the above-mentioned support has excellent ultraviolet transmittance, in the semiconductor wafer processing method of the present invention, before peeling off the adhesive tape of the present invention from the semiconductor wafer after the adhesive layer has hardened, the adhesive tape of the present invention can be peeled off more easily by irradiating the adhesive tape with laser light or ultraviolet light from the support side and peeling off the support.

[0095] In the processing method of the present invention, the method for curing the adhesive layer with light is, for example, light with a wavelength of 280 nm to 405 nm with an integrated light intensity of 1000 mJ / cm². 2 Methods of irradiation to achieve the above conditions include, for example, a wavelength of 405 nm and an illuminance of 100 mW / cm². 2 The integrated light intensity of the light is 2500 mJ / cm². 2 Examples include irradiating for 25 seconds to achieve the desired result. Examples of methods for curing the adhesive tape of the present invention by heat include heating at a temperature of 100°C to 200°C for 10 minutes to 2 hours.

[0096] The semiconductor wafer used in the semiconductor wafer processing method of the present invention is not particularly limited, and the semiconductor wafer processing method of the present invention can be used for processing all semiconductor wafers used in ordinary electronic components. The semiconductor wafer processing method of the present invention suppresses peeling of adhesive tape during cleaning, thinning, dicing, etc., even in the case of semiconductor wafers with electrodes, circuits, etc., that have irregularities on their surface, and allows for easy peeling of the adhesive tape from the semiconductor wafer surface after the adhesive tape has hardened, while suppressing the generation of adhesive residue.

[0097] A method for manufacturing a semiconductor device, comprising the steps of temporarily fixing a semiconductor wafer to a support using the adhesive tape of the present invention, and peeling off the adhesive tape after the adhesive layer has hardened by light or heat, is also one of the present inventions. According to the semiconductor device manufacturing method of the present invention, even in the case of semiconductor devices having an uneven surface, the processing quality of the manufactured semiconductor device can be further improved, and the yield during production can be improved, thereby further improving the manufacturing efficiency of semiconductor devices.

[0098] The semiconductor device manufacturing method of the present invention can be used, for example, in semiconductor device manufacturing processes such as film deposition, etching, cleaning, thinning, cutting, bumping, reflow, annealing, and ashing. [Effects of the Invention]

[0099] The present invention provides an adhesive composition that can achieve both excellent embedding properties for uneven surfaces and excellent peeling performance. Furthermore, the present invention provides an adhesive tape having an adhesive layer formed using the adhesive composition. Moreover, the present invention provides a method for processing semiconductor wafers and a method for manufacturing semiconductor devices using the adhesive tape. [Modes for carrying out the invention]

[0100] The embodiments of the present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0101] <Preparation of n-hexyl acrylate containing bio-derived carbon> Linoleic acid derived from castor oil was converted to linoleic acid hydroperoxide using lipoxygenase, and then a mixture containing n-hexylaldehyde was obtained using isomerase. By distillation of the obtained mixture, a bio-derived carbon-containing n-hexylaldehyde was obtained. Furthermore, by hydrogenation of the obtained bio-derived carbon-containing n-hexylaldehyde, a bio-derived carbon-containing n-hexyl alcohol was obtained. By esterifying the obtained bio-derived carbon-containing n-hexyl alcohol with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), a bio-derived carbon-containing n-hexyl acrylate was prepared.

[0102] <Preparation of n-heptyl acrylate containing bio-derived carbon> Ricinoleic acid derived from castor oil was cracked to obtain a mixture containing undecylenic acid and heptyl alcohol. Then, by distillation, the undecylenic acid was separated to obtain n-heptyl alcohol containing bio-derived carbon. By esterifying the n-heptyl alcohol containing bio-derived carbon with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), n-heptyl acrylate containing bio-derived carbon was prepared.

[0103] <Preparation of 1-methylheptyl acrylate containing bio-derived carbon> Ricinoleic acid derived from castor oil was dissolved in alkali to obtain a mixture containing sebacic acid and 1-methylheptyl alcohol. Sebacic acid was then separated from the mixture by distillation to obtain 1-methylheptyl alcohol containing bio-derived carbon. The obtained 1-methylheptyl alcohol containing bio-derived carbon was esterified with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) to prepare 1-methylheptyl acrylate containing bio-derived carbon.

[0104] (Example 1) (1) Preparation of (meth)acrylic copolymer A reactor equipped with a thermometer, stirrer, and condenser was prepared. 78.2 parts by mass of n-heptyl acrylate containing bio-derived carbon, prepared by the method described above, 19.8 parts by mass of 2-hydroxyethyl acrylate, 1.0 part by mass of acrylic acid, and 80 parts by mass of ethyl acetate were added to the reactor as alkyl (meth)acrylate. The reactor was then heated and reflux was initiated. Subsequently, 0.01 parts by mass of 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane was added to the reactor as a polymerization initiator, and polymerization was started under reflux. Next, 0.01 parts by mass of 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane was added 1 hour and 2 hours after the start of polymerization, and 0.05 parts by mass of t-hexylperoxypivalate was added 4 hours after the start of polymerization to continue the polymerization reaction. Then, 8 hours after the start of polymerization, ethyl acetate was added to the reactor and cooled while diluting to obtain an ethyl acetate solution containing a carbon-carbon double bond-less (meth)acrylic polymer. To the obtained ethyl acetate solution containing the carbon-carbon double bond-less (meth)acrylic polymer, 1.0 part by mass of 2-isocyanate ethyl methacrylate was added as a functional group-containing unsaturated compound and reacted to obtain a solution of (meth)acrylic copolymer A (hydroxyl value 90 mg KOH / g, acid value 7.0 mg KOH / g, carbon-carbon double bond equivalent 0.075 meq / g). The hydroxyl value and acid value of (meth)acrylic copolymer A were measured in accordance with the potentiometric titration method specified in JIS K 0070:1992. The weight-average molecular weight of the obtained (meth)acrylic copolymer A was measured using a Waters 2690 Separations Module as the measuring instrument, a Showa Denko GPC KF-806L as the column, and ethyl acetate as the solvent, under conditions of a sample flow rate of 1 mL / min and a column temperature of 40°C. The weight-average molecular weight was found to be 950,000.

[0105] (2) Manufacture of adhesive compositions and adhesive tapes To the obtained solution of (meth)acrylic copolymer A, 0.2 parts by mass of isocyanate-based crosslinking agent (Soken Chemical Co., Ltd., "Coronate L-45K") and 1.0 part by mass of photopolymerization initiator (IGM Resins, "Omnirad 369E") were added per 100 parts by mass of (meth)acrylic copolymer, and then mixed to obtain an ethyl acetate solution of the adhesive composition. An ethyl acetate solution of the obtained adhesive composition was applied to the release-treated surface of a 50 μm thick polyethylene terephthalate (PET) film using a doctor knife so that the adhesive layer thickness after drying was 30 μm. The adhesive layer was then dried at 110°C for 5 minutes to form the adhesive layer. Subsequently, the obtained adhesive layer was bonded to a 25 μm thick polyethylene naphthalate (PEN) film substrate and cured at 40°C for 5 days to obtain an adhesive tape with an adhesive layer on one side of the substrate.

[0106] (3) Content of bio-derived carbon in the adhesive layer The bio-derived carbon content of the obtained adhesive layer was measured in accordance with ASTM D6866-24. The results are shown in Table 3.

[0107] (4) Measurement of the gel fraction of the adhesive layer An ethyl acetate solution of the obtained adhesive composition was applied to the release-treated surface of a 50 μm thick polyethylene terephthalate (PET) film using a doctor's knife, so that the adhesive layer thickness after drying was 30 μm. This was then bonded to the release-treated surface of another 50 μm thick polyethylene terephthalate (PET) film, and cured at 40°C for 5 days to obtain an adhesive tape for gel fraction measurement. The obtained adhesive tape for gel fraction measurement was cut into 5 cm x 5 cm pieces, which were used as evaluation samples. From the obtained evaluation samples, only the adhesive layer (W0 g) was extracted and immersed in 50 mL of ethyl acetate. The mixture was shaken for 24 hours at 23°C and 200 rpm using a shaker. After shaking, the ethyl acetate and the adhesive layer that had absorbed and swollen with ethyl acetate were separated using a metal mesh (mesh size #200, W1 g). The separated adhesive layer was dried at 110°C for 1 hour. The mass W2 g of the adhesive layer containing the metal mesh after drying was measured, and the gel fraction (mass %) of the adhesive layer was calculated using the following formula. The results are shown in Table 3. Gel fraction (mass %) = 100 × (W2 - W1) / W0 (W0: initial mass of the adhesive layer, W1: initial mass of the metal mesh, W2: mass of the adhesive layer including the metal mesh after drying)

[0108] (5) Measurement of gel fraction after curing of the adhesive layer After cutting the adhesive tape for gel fraction measurement, obtained in the same manner as described in "(4) Measurement of gel fraction of adhesive layer" above, into a shape of 5 cm vertically and 5 cm horizontally, a high-pressure mercury lamp was used to measure the gel fraction at a wavelength of 405 nm and an illuminance of 100 mW / cm². 2 The integrated light intensity of the light is 2500 mJ / cm². 2 The adhesive layer was cured by irradiating it for 25 seconds to create an evaluation sample. The gel fraction (mass%) of the obtained evaluation samples was measured using the same method as described in "(4) Measurement of Gel Fraction of Adhesive Layer" above, and the gel fraction (mass%) after curing of the adhesive layer was obtained. The results are shown in Table 3.

[0109] (6) Measurement of the shear storage modulus of the adhesive layer at 23°C Multiple adhesive tapes for measuring shear storage modulus were prepared by applying an ethyl acetate solution of the obtained adhesive composition to the release-treated surface of a polyethylene terephthalate (PET) film with a thickness of 50 μm using a doctor knife, so that the adhesive layer thickness was 50 μm after drying, and then bonding it to the release-treated surface of a polyethylene terephthalate (PET) film with a thickness of 50 μm. The tapes were then left to cure at 40°C for 5 days. Evaluation samples were prepared by stacking only the adhesive layers of the multiple adhesive tapes obtained for measuring shear storage modulus so that the thickness was between 400 μm and 1 mm. For the evaluation samples, dynamic viscoelastic spectra were measured using a viscoelastic spectrometer (IT Measurement Control Co., Ltd., "DVA-200") under the conditions of simple heating mode, heating rate of 10°C / min, shear direction, frequency of 10 Hz, and temperature range from -50°C to 300°C. The shear storage modulus (Pa) of the adhesive layer at 23°C was determined from these measurements. The results are shown in Table 3.

[0110] (7) Measurement of the tensile storage modulus at 23°C after the adhesive layer has hardened. Multiple adhesive tapes for measuring tensile storage modulus, prepared in the same manner as the adhesive tape for measuring shear storage modulus described in "(6) Measurement of shear storage modulus of the adhesive layer at 23°C" above, were stacked so that only the adhesive layers of each tape had a thickness of 400 μm to 1 mm. Then, using a high-pressure mercury lamp, the measurements were taken at a wavelength of 405 nm and an illuminance of 100 mW / cm². 2 The integrated light intensity of the light is 2500 mJ / cm². 2 The adhesive layer was cured by irradiating it for 25 seconds to create an evaluation sample. Dynamic viscoelastic spectra were measured for the prepared evaluation samples using a viscoelastic spectrometer (IT Measurement Control Co., Ltd., "DVA-200") under the conditions of simple heating mode, heating rate of 10°C / min, tensile direction, frequency of 10 Hz, and temperature range from -50°C to 300°C. The tensile storage modulus (Pa) at 23°C after curing of the adhesive layer was determined from these measurements. The results are shown in Table 3.

[0111] (8) Measurement of the 180° peel force of adhesive tape on SUS The adhesive tape obtained in "(2) Manufacturing of adhesive composition and adhesive tape" described above was cut into a flat rectangular shape with a width of 25 mm and a length of 100 mm, and was bonded to a SUS plate (SUS304 plate washed with ethanol and then wiped dry) by passing a 2 kg rubber roller back and forth at a speed of 300 mm / min. After that, it was cured at 23°C and 50% RH for 20 minutes to prepare a test sample. The obtained test sample was subjected to a tensile test in accordance with JIS Z0237, under conditions of 23°C, 50% RH, tensile speed of 300 mm / min, and a peel angle of 180°, and the 180° peel force (N / 25 mm) of the adhesive tape to SUS was measured. The results are shown in Table 3.

[0112] (9) Measurement of the 180° peel force of adhesive tape on SUS after the adhesive layer has hardened. Using the same method as described in "(8) Measurement of 180° peel force of adhesive tape on SUS" above, the adhesive tape obtained in "(2) Manufacturing of adhesive composition and adhesive tape" above was bonded to a SUS plate (SUS304 plate washed with ethanol and then wiped dry), and then cured at 23°C and 50% RH for 20 minutes. Furthermore, a high-pressure mercury lamp was used to measure the illuminance at a wavelength of 405 nm and an illuminance of 100 mW / cm². 2 The integrated light intensity of the light is 2500 mJ / cm². 2 A test sample was prepared by curing an adhesive tape, which had been bonded to a SUS plate, by irradiating it for 25 seconds. A tensile test was performed on the obtained test sample in accordance with JIS Z0237, at 23°C, 50%RH, and a tensile speed of 300 mm / min, with a peel angle of 180°. The 180° peel force (N / 25 mm) of the adhesive tape against SUS after the adhesive layer had hardened was measured. The results are shown in Table 3.

[0113] <Rating> The adhesive tapes obtained in "(2) Manufacturing of adhesive compositions and adhesive tapes" described above were evaluated as follows. The results are shown in Table 3.

[0114] (1) Ability to fill in uneven surfaces The obtained adhesive tape was cut into a 20 cm diameter circle and attached in a vacuum to the stepped side of a stepped silicon wafer (20 cm diameter, 725 μm thickness) with a 10 μm step. The sample was then left to stand for 1 hour under conditions of 23°C and 50% RH to prepare the measurement sample. The stepped silicon wafer was prepared by making a 10 μm cut on the surface of a wafer (Φ8 inch, 725 μm thickness) using a dicing device (DISCO Corporation, "DFD6360"). The wafer surface of the measurement sample was observed using an optical microscope (Keyence Corporation, "VHX-970F", 10x magnification), and the embedding ability of the adhesive tape to uneven surfaces (uneven surface embedding ability) was evaluated according to the following criteria. • ◎: No void was found between the wafer and the adhesive tape. • ○: The size of the void between the wafer and the adhesive tape was less than 5% of the total surface area of ​​the adhesive surface. • ×: The size of the gap between the wafer and the adhesive tape was 5% or more of the total surface area of ​​the adhesive surface.

[0115] (2) Peeling performance (2-1)Residue The adhesive tape of the measurement sample used for the evaluation of "(ability to embed uneven surfaces)" described above was measured at a wavelength of 405 nm and an illuminance of 100 mW / cm². 2 The integrated light intensity of the light is 2500 mJ / cm². 2 The adhesive tape was cured by irradiating it for 25 seconds, and the cured adhesive tape was peeled off the stepped silicon wafer using a release tape. The surface of the stepped silicon wafer from which the adhesive tape had been peeled off was observed using an optical microscope (Keyence Corporation, "VHX-970F", 10x magnification), and the residue was evaluated according to the following criteria to determine the peeling performance of the adhesive tape. • ◎: No residue was found on the wafer surface. • ○: Residue on the wafer surface was less than 5% of the total surface area of ​​the adhesive surface. • ×: Residue on the wafer surface covered more than 5% of the total surface area of ​​the adhesive surface.

[0116] (2-2) Wafer cracking The obtained adhesive tape was cut into a circle with a diameter of 20 cm and attached in vacuum to the stepped side of a stepped silicon wafer (20 cm in diameter, 725 μm thick) with a step of 10 μm, which was prepared using the same method as described above for "(embedding properties for uneven surfaces)". Furthermore, grinding and polishing were performed on the non-stepped side of the stepped silicon wafer to which the adhesive tape was attached, and the thickness of the stepped silicon wafer was ground down to 50 μm to prepare a measurement sample. The prepared measurement sample was applied to the adhesive tape at a wavelength of 405 nm and an illuminance of 100 mW / cm². 2 The integrated light intensity of the light is 2500 mJ / cm². 2 The adhesive tape was cured by irradiating it for 25 seconds, and the cured adhesive tape was peeled off with a release tape. The wafer cracks of the stepped silicon wafer from which the adhesive tape had been peeled off were visually observed. The same procedure was performed on five measurement samples, and the peeling performance of the adhesive tape was evaluated according to the following criteria. • ◎: There were 0 broken or uneven silicon wafers out of 10. • ○: One out of ten silicon wafers had a cracked or stepped surface. • ×: Two or more out of ten silicon wafers had cracks or uneven edges.

[0117] (Examples 2-4, 6-12, 14-17, 19-21, 23-24, Comparative Examples 1-5) Except for the fact that the composition of the (meth)acrylic copolymer was set to the one shown in Tables 1-2 in "(1) Preparation of (meth)acrylic copolymer" and the composition of the adhesive composition and adhesive tape was set to the one shown in Tables 3-6 in "(2) Production of adhesive composition and adhesive tape" described above, the (meth)acrylic copolymer was prepared, and the adhesive composition and adhesive tape were produced in the same manner as in Example 1. The (meth)acrylic copolymer, adhesive layer, and adhesive tape were measured and evaluated in the same manner as in Example 1. The results are shown in Tables 1-6.

[0118] (Example 5) Except for the differences in the above-mentioned "(1) Preparation of (meth)acrylic copolymer" being carried out using 300 parts by mass of ethyl acetate with the composition shown in Table 1, and the difference in the above-mentioned "(2) Production of adhesive composition and adhesive tape" being the composition shown in Table 3, the (meth)acrylic copolymer, adhesive composition, and adhesive tape were prepared in the same manner as in Example 1, and the (meth)acrylic copolymer, adhesive layer, and adhesive tape were measured and evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 3.

[0119] (Example 13) Except for the fact that the composition of the (meth)acrylic copolymer was used as shown in Table 1 in "(1) Preparation of (meth)acrylic copolymer" and the composition of the adhesive composition and the type of substrate were used as shown in Table 4 in "(2) Manufacturing of adhesive composition and adhesive tape" described above, the (meth)acrylic copolymer, adhesive composition, and adhesive tape were manufactured in the same manner as in Example 1, and the (meth)acrylic copolymer, adhesive layer, and adhesive tape were measured and evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 4.

[0120] (Example 18) In the above-mentioned "(1) Preparation of (meth)acrylic copolymer," the composition was as shown in Table 1, and in the above-mentioned "(2) Manufacturing of adhesive composition and adhesive tape," the composition of the adhesive composition was as shown in Table 5. Furthermore, in the above-mentioned "(5) Measurement of gel fraction after curing of adhesive layer," "(7) Measurement of tensile storage modulus at 23°C after curing of adhesive layer," "(9) Measurement of 180° peel force of adhesive tape against SUS after curing of adhesive layer," "(2-1) Residue," and "(2-2) Wafer cracking," an ultra-high pressure mercury lamp was used with a wavelength of 405 nm and an illuminance of 100 mW / cm. 2 The integrated light intensity of the light is 2500 mJ / cm². 2Instead of irradiating for 25 seconds, the adhesive layer was cured by heating in a high-temperature oven at 150°C for 10 minutes. Otherwise, the (meth)acrylic copolymer was prepared, and the adhesive composition and adhesive tape were made in the same manner as in Example 1. The (meth)acrylic copolymer, adhesive layer, and adhesive tape were measured and evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 5.

[0121] (Example 22) Except for the differences in the above-mentioned "(1) Preparation of (meth)acrylic copolymer" being carried out using 40 parts by mass of ethyl acetate with the composition shown in Table 2, and the difference in the above-mentioned "(2) Production of adhesive composition and adhesive tape" being the composition shown in Table 5, the (meth)acrylic copolymer, adhesive composition, and adhesive tape were prepared in the same manner as in Example 1, and the (meth)acrylic copolymer, adhesive layer, and adhesive tape were measured and evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 5.

[0122] The abbreviations for each material in Tables 1 and 2 refer to the following compounds. HexA:n-hexylacrylate • HPA: n-heptylacrylate • 2OA:1-Methylheptylacrylate 2-EHA: 2-ethylhexyl acrylate • BA: n-butyl acrylate • HEA: 2-hydroxyethyl acrylate AAc: Acrylic acid • MOI: 2-Isocyanate ethyl methacrylate

[0123] Furthermore, the base materials in Tables 3-6 refer to the following base materials. • PEN (polyethylene naphthalate) containing film: Teonex (manufactured by Toyobo Co., Ltd., thickness: 25 μm) • PET (polyethylene terephthalate) containing film: Lumirror (manufactured by Toray Industries, Ltd., thickness: 25 μm)

[0124] [Table 1]

[0125] [Table 2]

[0126] [Table 3]

[0127] [Table 4]

[0128] [Table 5]

[0129] [Table 6] [Industrial applicability]

[0130] The present invention provides an adhesive composition that can achieve both excellent embedding properties for uneven surfaces and excellent peeling performance. Furthermore, the present invention provides an adhesive tape having an adhesive layer formed using the adhesive composition. Moreover, the present invention provides a method for processing semiconductor wafers and a method for manufacturing semiconductor devices using the adhesive tape.

Claims

1. It contains (meth)acrylic copolymer, The (meth)acrylic copolymer comprises constituent units derived from alkyl (meth)acrylate having a linear or branched C6 alkyl group, The (meth)acrylic copolymer has a carbon-carbon double bond in its side chain. An adhesive composition characterized by the following features.

2. The adhesive composition according to claim 1, wherein the alkyl (meth)acrylate having a linear or branched C6 alkyl group comprises n-hexyl (meth)acrylate.

3. The adhesive composition according to claim 2, wherein the n-hexyl (meth)acrylate is synthesized from n-hexyl alcohol, which is a biological material, and (meth)acrylic acid.

4. The adhesive composition according to claim 1, 2, or 3, wherein the content of constituent units derived from the linear or branched alkyl (meth)acrylate having a C6 alkyl group in the (meth)acrylic copolymer is 15% by mass or more.

5. The adhesive composition according to claim 1, 2, or 3, wherein the (meth)acrylic copolymer comprises structural units derived from a polar functional group-containing monomer.

6. The adhesive composition according to claim 5, wherein the total content of constituent units derived from the polar functional group-containing monomer in the (meth)acrylic copolymer is 0.01% by mass or more and 30% by mass or less.

7. The adhesive composition according to claim 1, 2, or 3, wherein the (meth)acrylic copolymer has a carbon-carbon double bond equivalent of 0.05 meq / g or more.

8. The adhesive composition according to claim 5, wherein the acid value of the (meth)acrylic copolymer is 10 mg KOH / g or less.

9. The adhesive composition according to claim 5, wherein the hydroxyl value of the (meth)acrylic copolymer is 5.0 mg KOH / g or more and 100 mg KOH / g or less.

10. The adhesive composition according to claim 1, 2, or 3, wherein the weight-average molecular weight of the (meth)acrylic copolymer is 200,000 or more and 2,000,000 or less.

11. Furthermore, the adhesive composition according to claim 1, 2, or 3 further contains at least one polymerization initiator selected from the group consisting of photopolymerization initiators and thermal polymerization initiators.

12. Furthermore, the adhesive composition according to claim 1, 2, or 3, further containing an inorganic filler.

13. Furthermore, the adhesive composition according to claim 1, 2, or 3 further contains a polyfunctional oligomer or a polyfunctional monomer.

14. Furthermore, the adhesive composition according to claim 1, 2, or 3 further contains a gas generating agent.

15. Furthermore, the adhesive composition according to claim 1, 2, or 3, further containing a tackifier.

16. An adhesive tape having an adhesive layer formed using the adhesive composition according to claim 1, 2, or 3.

17. The adhesive tape according to claim 16, wherein the content of bio-derived carbon in the adhesive layer is 10% or more.

18. The gel fraction of the adhesive layer is 10% by mass or more and 90% by mass or less. After heating at 150°C for 1 hour, or after emitting light of any wavelength within the range of 280 nm to 405 nm with an integrated light intensity of 1000 mJ / cm² ２ The adhesive tape according to claim 16, wherein the gel fraction of the adhesive layer after irradiation to the above extent is 90% by mass or more.

19. The shear storage modulus of the adhesive layer at 23°C is 1.2 × 10⁻⁶. ５ It is less than or equal to Pa, After heating at 150°C for 1 hour, or after emitting light of any wavelength within the range of 280 nm to 405 nm with an integrated light intensity of 1000 mJ / cm² ２ The tensile storage modulus of the adhesive layer at 23°C after irradiation as described above is 1.0 × 10⁻⁶. ６ It is Pa or higher. The adhesive tape according to claim 16.

20. The 180° peeling force against SUS is 0.3 N / 25 mm or more. After heating at 150°C for 1 hour, or after emitting light of any wavelength within the range of 280 nm to 405 nm with an integrated light intensity of 1000 mJ / cm² ２ The 180° peeling force on the SUS after irradiation is 0.30 N / 25 mm or less. The adhesive tape according to claim 16.

21. The adhesive tape according to claim 16, used for temporarily fixing electronic equipment components.

22. A method for processing a semiconductor wafer, comprising the steps of temporarily fixing a semiconductor wafer to a support using the adhesive tape described in claim 21, and peeling off the adhesive tape after the adhesive layer has been cured by light or heat.

23. A method for manufacturing a semiconductor device, comprising the steps of temporarily fixing a semiconductor wafer to a support using the adhesive tape described in claim 21, and peeling off the adhesive tape after the adhesive layer has been cured by light or heat.

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