Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P54/00—Cutting or separating of wafers, substrates or parts of devices
  • H10P54/90—Auxiliary processes or arrangements
  • H10P54/92—Auxiliary processes or arrangements for protecting or reinforcing the surface of wafers or substrates during cutting or separating, e.g. using adhesive tapes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
  • C09J133/04—Homopolymers or copolymers of esters
  • C09J133/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
  • C09J133/062—Copolymers with monomers not covered by C09J133/06
  • C09J133/066—Copolymers with monomers not covered by C09J133/06 containing -OH groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/04—Acids; Metal salts or ammonium salts thereof
  • C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/10—Esters
  • C08F220/12—Esters of monohydric alcohols or phenols
  • C08F220/16—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms
  • C08F220/18—Esters of monohydric alcohols or phenols of phenols or of alcohols containing two or more carbon atoms with acrylic or methacrylic acids
  • C08F220/1807—C7-(meth)acrylate, e.g. heptyl (meth)acrylate or benzyl (meth)acrylate
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/10—Esters
  • C08F220/20—Esters of polyhydric alcohols or phenols, e.g. 2-hydroxyethyl (meth)acrylate or glycerol mono-(meth)acrylate
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
  • C09J11/02—Non-macromolecular additives
  • C09J11/06—Non-macromolecular additives organic
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
  • C09J133/04—Homopolymers or copolymers of esters
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/10—Adhesives in the form of films or foils without carriers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/38—Pressure-sensitive adhesives [PSA]
  • C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
  • C09J7/385—Acrylic polymers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P72/00—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof
  • H10P72/70—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping
  • H10P72/74—Handling or holding of wafers, substrates or devices during manufacture or treatment thereof for supporting or gripping using temporarily an auxiliary support
  • H10P72/7402—Wafer tapes, e.g. grinding or dicing support tapes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
  • C09J2203/326—Applications of adhesives in processes or use of adhesives in the form of films or foils for bonding electronic components such as wafers, chips or semiconductors
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2301/00—Additional features of adhesives in the form of films or foils
  • C09J2301/30—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier
  • C09J2301/312—Additional features of adhesives in the form of films or foils characterized by the chemical, physicochemical or physical properties of the adhesive or the carrier parameters being the characterizing feature
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2301/00—Additional features of adhesives in the form of films or foils
  • C09J2301/50—Additional features of adhesives in the form of films or foils characterized by process specific features
  • C09J2301/502—Additional features of adhesives in the form of films or foils characterized by process specific features process for debonding adherents
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2433/00—Presence of (meth)acrylic polymer

Definitions

• the present invention relates to an adhesive composition.
• the present invention also relates to an adhesive tape having an adhesive layer containing the adhesive composition. Furthermore, the present invention also relates to a method for treating a semiconductor wafer and a method for manufacturing a semiconductor device using the adhesive tape.
• Adhesive tapes having an adhesive layer containing an adhesive composition have been widely used to fasten components in electronic components, vehicles, houses, and building materials (e.g., Patent Documents 1 to 3). Specifically, 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.
• acrylic adhesives containing (meth)acrylic copolymers have been widely used as adhesive compositions with excellent adhesive strength.
• acrylic monomers that constitute the (meth)acrylic copolymers include (meth)acrylic acid alkyl esters such as butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate.
• Pressure-sensitive adhesive compositions and pressure-sensitive adhesive tapes used for temporarily fixing electronic components such as semiconductors are required to have excellent embedding properties for the uneven surfaces of bump wafers and the like to be temporarily fixed, since the surfaces of the bump wafers and the like to be temporarily fixed are uneven. At the same time, there is a need to be able to peel the electronic components to be temporarily fixed while suppressing the generation of adhesive residue, and therefore excellent peeling performance is also required.
• an acrylic pressure-sensitive adhesive containing a (meth)acrylic copolymer using butyl (meth)acrylate as the main raw material component is used, the adhesive has insufficient ability to fill unevenness.
• the adhesive when an acrylic pressure-sensitive adhesive containing a (meth)acrylic copolymer using 2-ethylhexyl (meth)acrylate as the main raw material component is used, the adhesive has excellent ability to fill unevenness, but there is a problem that the adhesive is easily torn when peeled off, and adhesive residue is likely to be left on the electronic components to be temporarily fixed.
• the present invention aims to provide an adhesive composition that can achieve both excellent embedding properties for unevenness and excellent peeling performance.
• the present invention aims to provide an adhesive tape having an adhesive layer containing the adhesive composition.
• the present invention aims to provide a method for treating semiconductor wafers and a method for manufacturing semiconductor devices that use the adhesive tape.
• the present disclosure 1 is a pressure-sensitive adhesive composition containing a (meth)acrylic copolymer, the (meth)acrylic copolymer containing a structural unit derived from n-heptyl (meth)acrylate, and the (meth)acrylic copolymer having a carbon-carbon double bond in a side chain.
• the present disclosure 2 is the pressure-sensitive adhesive composition of the present disclosure 1, in which the content of the structural units derived from the n-heptyl (meth)acrylate in the (meth)acrylic copolymer is 15 mass % or more.
• the present disclosure 3 is the pressure-sensitive adhesive composition according to the present disclosure 1 or 2, wherein the (meth)acrylic copolymer has a carbon-carbon double bond equivalent of 0.05 meq/g or more.
• the present disclosure 4 is the pressure-sensitive adhesive composition according to the present disclosure 1, 2, or 3, wherein the (meth)acrylic copolymer contains a constituent unit derived from a polar functional group-containing monomer.
• the present disclosure 5 is the pressure-sensitive adhesive composition of the present disclosure 4, wherein the total content of structural 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.
• the present disclosure 6 is the pressure-sensitive adhesive composition according to the present disclosure 4 or 5, wherein the (meth)acrylic copolymer has an acid value of 10 mgKOH/g or less.
• the present disclosure 7 is the pressure-sensitive adhesive composition according to the present disclosure 4, 5, or 6, wherein the (meth)acrylic copolymer has a hydroxyl value of 5 mgKOH/g or more and 100 mgKOH/g or less.
• the present disclosure 8 is the pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, 5, 6, or 7, wherein the (meth)acrylic copolymer has a weight average molecular weight of 200,000 or more and 2,000,000 or less.
• the present disclosure 9 is the pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, 5, 6, 7, or 8, further comprising a photopolymerization initiator.
• the present disclosure 10 is the pressure-sensitive adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, or 9, further comprising an inorganic filler.
• the present disclosure 11 is the pressure-sensitive adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, further comprising a polyfunctional oligomer or a polyfunctional monomer.
• the present disclosure 12 is a pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11, further comprising a gas generating agent.
• the present disclosure 13 is a pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, further comprising a tackifier.
• the present disclosure 14 is an adhesive tape having an adhesive layer containing the adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13.
• the present disclosure 15 is the pressure-sensitive adhesive tape of the present disclosure 14, wherein the pressure-sensitive adhesive layer has a content of biological carbon of 10% or more.
• the present disclosure 16 is a pressure-sensitive adhesive tape according to the present disclosure 14 or 15, in which the pressure-sensitive adhesive layer has a gel fraction of 10 mass% or more and 90 mass% or less, and the pressure-sensitive adhesive layer has a gel fraction of 90 mass% or more after heating at 150°C for 1 hour or after being irradiated with light having a wavelength within a range of 280 nm or more and 405 nm or less so that the integrated light amount is 1000 mJ/cm2 or more.
• Disclosure 17 is a pressure-sensitive adhesive tape according to Disclosure 14, 15, or 16, in which the pressure-sensitive adhesive layer has a shear storage modulus of 1.2 x 10 5 Pa or less at 23°C, and a tensile storage modulus of the pressure-sensitive adhesive layer at 23°C of 1.0 x 10 6 Pa or more after heating at 150°C for 1 hour or after irradiating the pressure-sensitive adhesive layer with light of any wavelength within the range of 280 nm or more and 405 nm or less so that the accumulated light amount is 1000 mJ/cm 2 or more.
• Disclosure 18 is a pressure-sensitive adhesive tape according to Disclosure 14, 15, 16, or 17, in which the 180° peel force from SUS is 0.3 N/25 mm or more, and the 180° peel force from SUS is 0.3 N/25 mm or less after heating at 150°C for 1 hour or after irradiation with light having any wavelength within the range of 280 nm or more and 405 nm or less so that the integrated light amount is 1000 mJ/ cm2 or more.
• the present disclosure 19 is an adhesive tape according to the present disclosure 14, 15, 16, 17, or 18, which is used for temporarily fixing a semiconductor wafer.
• the present disclosure 20 is a method for treating a semiconductor wafer, comprising the steps of temporarily fixing a semiconductor wafer to a support using the adhesive tape of the present disclosure 19, and peeling off the adhesive tape after the adhesive layer is cured by light or heat.
• the present disclosure 21 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 the present disclosure 19, and peeling off the adhesive tape after the adhesive layer is cured by light or heat. The present invention will be described in detail below.
• the present inventors have found that in a pressure-sensitive adhesive composition containing a (meth)acrylic copolymer, the embedding ability into unevenness and the peeling performance of the pressure-sensitive adhesive composition can be improved by using a (meth)acrylic copolymer containing a structural unit derived from n-heptyl (meth)acrylate as the (meth)acrylic copolymer.
• the present inventors have focused on the fact that the adhesive strength of the pressure-sensitive adhesive composition is significantly reduced and the peeling performance is improved by curing the (meth)acrylic copolymer, and have investigated how to further improve the peeling performance of the pressure-sensitive adhesive composition by introducing a carbon-carbon double bond into the side chain of the (meth)acrylic copolymer containing a structural unit derived from n-heptyl (meth)acrylate, thereby giving the (meth)acrylic copolymer a structure that can be cured by irradiation with light, heating, or the like.
• a pressure-sensitive adhesive composition can be obtained that is capable of achieving both excellent embedding properties into unevenness and excellent peeling performance, and thus completed the present invention.
• the pressure-sensitive adhesive composition of the present invention contains a (meth)acrylic copolymer.
• the (meth)acrylic copolymer contains structural units derived from n-heptyl (meth)acrylate.
• n-Heptyl (meth)acrylate can lower the glass transition temperature (Tg) of the polymer to increase its flexibility. Therefore, by including a structural unit derived from n-heptyl (meth)acrylate in the (meth)acrylic copolymer, the pressure-sensitive adhesive composition of the present invention has excellent embedding ability for unevenness, and can be easily peeled off from uneven surfaces while suppressing the occurrence of adhesive residue, resulting in excellent peeling performance.
• "(meth)acrylic” means acrylic or methacrylic
• (meth)acrylate” means acrylate or methacrylate.
• the n-heptyl(meth)acrylate preferably contains bio-derived carbon.
• the content of bio-derived carbon in the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition of the present invention described below increases, and the environmental load caused by a pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer can be further reduced.
• "containing carbon derived from a living organism” means that the bio-based carbon content of the compound is 1% or more as measured by ASTM D6866-22.
• the n-heptyl(meth)acrylate in the constitutional unit derived from the n-heptyl(meth)acrylate contains carbon derived from a living organism
• the n-heptyl(meth)acrylate is preferably synthesized by esterification of n-heptyl alcohol, which is a living organism material, with (meth)acrylic acid. It is also preferably synthesized by transesterification of n-heptyl alcohol, which is a living organism material, with a (meth)acrylic acid ester.
• the biologically derived n-heptyl alcohol can be obtained inexpensively and easily, for example, by cracking a material extracted from an animal or plant (such as ricinoleic acid derived from castor oil).
• the preferred lower limit of the content of the structural unit derived from the n-heptyl (meth)acrylate in the (meth)acrylic copolymer is 15% by mass.
• the adhesive composition of the present invention has increased flexibility, and therefore has excellent embedding properties for uneven surfaces, and can be more easily peeled off while suppressing the occurrence of adhesive residue from uneven surfaces.
• the content of the structural unit derived from the n-heptyl (meth)acrylate containing bio-derived carbon is 15% by mass or more, the content of bio-derived carbon in the adhesive layer of the adhesive tape described below can be further increased.
• a more preferred lower limit of the content of the structural unit derived from the n-heptyl (meth)acrylate is 35% by mass, and an even more preferred lower limit is 50% by mass.
• the (meth)acrylic copolymer preferably contains structural units derived from a polar functional group-containing monomer described below and structural units derived from a functional group-containing unsaturated compound described below, and therefore the upper limit is preferably 98% by mass.
• the upper limit of the content of the structural units derived from the n-heptyl (meth)acrylate is more preferably 95% by mass, and even more preferably 90% by mass.
• the (meth)acrylic copolymer has a carbon-carbon double bond in the side chain. Since the (meth)acrylic copolymer has a carbon-carbon double bond in the side chain, the adhesive strength of the pressure-sensitive adhesive composition of the present invention can be significantly reduced by curing through heating, irradiation with light, or the like, and the pressure-sensitive adhesive composition of the present invention can be easily peeled off when peeled off, so that the pressure-sensitive adhesive composition of the present invention has excellent peeling performance.
• the term “side chain” refers to a branched structural portion extending from the main chain when the longest chain in the (meth)acrylic copolymer is regarded as the main chain.
• carbon-carbon double bond does not include carbon-carbon double bonds that constitute aromatic rings.
• Examples of methods for introducing carbon-carbon double bonds into the side chains of the (meth)acrylic copolymer include reacting a (meth)acrylic polymer without carbon-carbon double bonds obtained by copolymerizing the n-heptyl (meth)acrylate, a polar functional group-containing monomer described below, or other monomers described below with a compound having a carbon-carbon double bond and a functional group capable of reacting with a carboxy group, hydroxyl group, or the like in the polymer (hereinafter also referred to as a "functional group-containing unsaturated compound").
• Examples of the functional group-containing unsaturated compound include the same as the polar functional group-containing monomer described below, depending on the functional group in the (meth)acrylic polymer to which no carbon-carbon double bond has been introduced.
• the functional group in the (meth)acrylic polymer to which no carbon-carbon double bond has been introduced is a carboxy group, for example, an epoxy group-containing monomer or an isocyanate group-containing monomer is used.
• the functional group in the (meth)acrylic polymer to which no carbon-carbon double bond has been introduced is a hydroxyl group, for example, an isocyanate group-containing monomer is used.
• the functional group in the (meth)acrylic polymer to which no carbon-carbon double bond has been introduced is an epoxy group, for example, a carboxy group-containing monomer or an amide group-containing monomer such as acrylamide is used.
• the functional group in the (meth)acrylic polymer to which no carbon-carbon double bond has been introduced is an amino group, for example, an epoxy group-containing monomer is used.
• the functional group-containing unsaturated compound include 2-methacryloyloxyethyl isocyanate (MOI), 2-acryloyloxyethyl isocyanate (AOI), and 1,1-(bisacryloyloxymethyl)ethyl isocyanate (BEI).
• the preferred lower limit of the content of the structural unit derived from the functional group-containing unsaturated compound in the (meth)acrylic copolymer is 0.1% by mass, and the preferred upper limit is 25% by mass.
• the adhesive composition of the present invention can be sufficiently cured when cured, and the adhesive composition of the present invention has better peeling performance.
• the adhesive composition of the present invention can maintain a suitable flexibility even after curing, and can be more easily peeled off from uneven surfaces while suppressing the occurrence of adhesive residue.
• the more preferred lower limit of the content of the structural unit derived from the functional group-containing unsaturated compound is 0.5% by mass, and the more preferred upper limit is 20% by mass.
• the (meth)acrylic copolymer preferably further contains a constituent unit derived from a polar functional group-containing monomer.
• a constituent unit derived from a polar functional group-containing monomer in the (meth)acrylic copolymer, the cohesive force of the pressure-sensitive adhesive composition of the present invention is increased, and the adhesive composition can be more easily peeled off from an uneven surface while suppressing the occurrence of adhesive residue.
• the adhesive force of the pressure-sensitive adhesive composition of the present invention can be reduced by reacting the functional group derived from the constituent unit derived from the polar functional group-containing monomer with the crosslinking agent by irradiation with light, heating, or the like during peeling, and the pressure-sensitive adhesive composition of the present invention has superior peeling performance.
• constituent units derived from the polar functional group-containing monomer include constituent units derived from carboxy 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.
• the (meth)acrylic copolymer contains at least one selected from the group consisting of constituent units derived from carboxy group-containing monomers and constituent units derived from hydroxyl group-containing monomers.
• Examples of the carboxy group-containing monomer include acrylic acid and methacrylic acid.
• Examples of the hydroxyl group-containing monomer include hydroxyethyl acrylate and hydroxyethyl methacrylate.
• Examples of the epoxy group-containing monomer include glycidyl acrylate and glycidyl methacrylate.
• Examples of the isocyanate group-containing monomer include isocyanate ethyl acrylate and isocyanate ethyl methacrylate.
• Examples of the amino group-containing monomer include aminoethyl acrylate and aminoethyl methacrylate.
• the preferred lower limit of the total content ratio of the constituent units derived from the polar functional group-containing monomer in the (meth)acrylic copolymer is 0.01% by mass, and the preferred upper limit is 30% by mass.
• the cohesive force of the pressure-sensitive adhesive composition of the present invention is greater, and the adhesive composition can be more easily peeled off from the uneven surface while suppressing the occurrence of adhesive residue.
• the adhesive force of the pressure-sensitive adhesive composition of the present invention can be reduced by reacting the functional group derived from the constituent units derived from the polar functional group-containing monomer with the crosslinking agent by irradiation with light or heating, etc., during peeling, and the pressure-sensitive adhesive composition of the present invention has better peeling performance.
• the total content ratio of the constituent units derived from the polar functional group-containing monomer is 30% by mass or less, the pressure-sensitive adhesive composition of the present invention does not become too hard, has better embedding properties for unevenness, and has sufficient initial adhesive strength.
• a more preferred lower limit for the total content of the structural units derived from the polar functional group-containing monomer is 0.1% by mass, a more preferred upper limit is 28% by mass, a still more preferred lower limit is 1% by mass, and a still more preferred upper limit is 25% by mass.
• the polar functional group-containing monomers may be used alone or in combination of two or more kinds.
• the (meth)acrylic copolymer may contain a constituent unit derived from another monomer other than the constituent unit derived from the n-heptyl (meth)acrylate and the constituent unit derived from the polar functional group-containing monomer.
• the other monomers include alkyl (meth)acrylates other than the n-heptyl (meth)acrylate.
• alkyl (meth)acrylate examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, and the like.
• acrylates examples include uryl (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 and (meth)acrylic acid, esters of alcohols having a total of 18 carbon atoms and one or two methyl groups in the linear main chain and (meth)acrylic acid, behenyl (meth)acrylate, and arachidyl (meth)acrylate.
• alkyl (meth)acrylates may be used alone or in combination of two or more kinds.
• Examples of the other monomers include cyclohexyl (meth)acrylate, benzyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, polypropylene glycol mono(meth)acrylate, etc.
• examples of the other monomers that can be used include various monomers used in general acrylic polymers, such as vinyl carboxylates such as vinyl acetate, and styrene. These other monomers may be used alone or in combination of two or more.
• Examples of a method for producing the (meth)acrylic copolymer include a method in which a monomer mixture containing the n-heptyl (meth)acrylate and the polar functional group-containing monomer or the like is copolymerized by radical reaction in the presence of a polymerization initiator, and then the obtained (meth)acrylic polymer having no carbon-carbon double bond introduced therein is reacted with a functional group-containing unsaturated compound.
• a method for subjecting the monomer mixture to a radical reaction i.e., a polymerization method
• a conventionally known method is used, and examples thereof include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization, and the like.
• Examples of the polymerization initiator used for producing the (meth)acrylic copolymer include organic peroxides and azo compounds.
• Examples of the 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.
• the azo compound examples include azobisisobutyronitrile and azobiscyclohexanecarbonitrile. These polymerization initiators may be used alone or in combination of two or more.
• the polymerization initiator may be, for example, an organic tellurium polymerization initiator.
• the organic tellurium polymerization initiator is not particularly limited as long as it is one that is generally used in living radical polymerization, and may be, for example, an organic tellurium compound, an organic telluride compound, etc.
• the azo compound may also be used as a polymerization initiator used to produce the (meth)acrylic copolymer in living radical polymerization in order to accelerate the polymerization rate.
• the lower limit of the carbon-carbon double bond equivalent of the (meth)acrylic copolymer is preferably 0.05 meq/g.
• the pressure-sensitive adhesive composition of the present invention has better release performance.
• the lower limit of the carbon-carbon double bond equivalent of the (meth)acrylic copolymer is more preferably 0.06 meq/g, and even more preferably 0.075 meq/g.
• the preferred upper limit of the carbon-carbon double bond equivalent of the (meth)acrylic copolymer is 3.5 meq/g.
• the pressure-sensitive adhesive composition of the present invention can maintain a suitable flexibility even after curing, and can be more easily peeled off from uneven surfaces while suppressing the occurrence of adhesive residue.
• the more preferred upper limit of the carbon-carbon double bond equivalent of the (meth)acrylic copolymer is 2.0 meq/g.
• carbon-carbon double bond equivalent of the (meth)acrylic copolymer refers to the milliequivalent of carbon-carbon double bonds per gram of the (meth)acrylic copolymer (meq/g).
• the upper limit of the acid value of the (meth)acrylic copolymer is preferably 10 mgKOH/g. By making the acid value of the (meth)acrylic copolymer 10 mgKOH/g or less, the pressure-sensitive adhesive composition of the present invention does not become too hard, has excellent embedding properties for unevenness, and has sufficient initial adhesive strength.
• the upper limit of the acid value of the (meth)acrylic copolymer is more preferably 9 mgKOH/g, and even more preferably 8 mgKOH/g.
• the lower limit of the acid value of the (meth)acrylic copolymer is not particularly limited, and may be 0 mgKOH/g.
• the acid value is an index representing the content of carboxyl groups in a certain amount of sample.
• the hydroxyl value of the (meth)acrylic copolymer is the number of milligrams of potassium hydroxide required to neutralize the acid contained in 1 g of the (meth)acrylic copolymer, and can be calculated by measuring based on the potentiometric titration method specified in JIS K 0070:1992.
• the preferred lower limit of the hydroxyl value of the (meth)acrylic copolymer is 5 mgKOH/g, and the preferred upper limit is 100 mgKOH/g.
• the hydroxyl value of the (meth)acrylic copolymer is 5 mgKOH/g or more, the cohesive strength of the pressure-sensitive adhesive composition of the present invention is greater, so that the pressure-sensitive adhesive composition of the present invention can be easily peeled off while suppressing the occurrence of adhesive residue from the uneven surface.
• the adhesive strength of the pressure-sensitive adhesive composition of the present invention can be reduced by reacting the functional group derived from the structural unit derived from the polar functional group-containing monomer with the crosslinking agent by irradiation with light or heating during peeling, so that the pressure-sensitive adhesive composition of the present invention has better peeling performance.
• the hydroxyl value of the (meth)acrylic copolymer is 100 mgKOH/g or less, the pressure-sensitive adhesive composition of the present invention does not become too hard, has better embedding properties for unevenness, and has sufficient initial adhesive strength.
• the hydroxyl value of the (meth)acrylic copolymer is more preferably 7 mgKOH/g at its lower limit, more preferably 95 mgKOH/g at its upper limit, still more preferably 9 mgKOH/g at its lower limit, and even more preferably 90 mgKOH/g at its upper limit.
• the hydroxyl value is an index representing the content of hydroxyl groups (hydroxyl groups) in a certain 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 by neutralization titration after acetylating 1 g of the (meth)acrylic copolymer, and can be calculated by measuring based on the potentiometric titration method specified in JIS K 0070:1992.
• the weight average molecular weight (Mw) of the (meth)acrylic copolymer is preferably 200,000 in lower limit and 2,000,000 in upper limit.
• the weight average molecular weight (Mw) of the (meth)acrylic copolymer is 200,000 or more, so that the pressure-sensitive adhesive composition of the present invention has sufficient initial adhesive strength.
• the weight average molecular weight (Mw) of the (meth)acrylic copolymer is 2,000,000 or less, so that the pressure-sensitive adhesive composition of the present invention does not become too hard, has excellent embedding properties for unevenness, and has sufficient initial adhesive strength.
• the weight average molecular weight (Mw) of the (meth)acrylic copolymer is more preferably 250,000 in lower limit, 1,800,000 in upper limit, 300,000 in lower limit, and 1,500,000 in upper limit.
• the weight average molecular weight of the (meth)acrylic copolymer can be determined, for example, by gel permeation chromatography (GPC) in terms of standard polystyrene. More specifically, the weight average molecular weight can be measured using, for example, a Waters 2690 Separations Module as a measuring instrument, a Showa Denko GPC KF-806L column, ethyl acetate as a solvent, at a sample flow rate of 1 mL/min and a column temperature of 40° C.
• the glass transition temperature (Tg) of the (meth)acrylic copolymer is not particularly limited, but a preferred upper limit is ⁇ 20° C.
• a preferred upper limit is ⁇ 20° C.
• the adhesive layer containing the adhesive composition of the present invention has improved conformability to unevenness, and therefore the adhesive strength, particularly to rough surfaces, is higher.
• a more preferred upper limit of 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.
• the lower limit of the glass transition temperature (Tg) of the 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 (meth)acrylic copolymer can be determined, for example, by differential scanning calorimetry.
• the pressure-sensitive adhesive composition of the present invention preferably further contains a polymerization initiator.
• the polymerization initiator reacts with the carbon-carbon double bond in the side chain of the (meth)acrylic copolymer, whereby the pressure-sensitive adhesive composition of the present invention is cured and the adhesive strength is reduced, resulting in more excellent peeling performance.
• the polymerization initiator may be a photopolymerization initiator or a thermal polymerization initiator.
• the pressure-sensitive adhesive composition of the present invention contains a photopolymerization initiator.
• photopolymerization initiator examples include those that are activated by irradiation with light having a wavelength of 250 to 800 nm.
• 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 benzyl dimethyl ketal and acetophenone diethyl ketal, phosphine oxide derivative compounds such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis( ⁇ 5-cyclopentadienyl)titanocene derivative compounds, benzophenone, Michler's ketone, chlorothioxanthone, todecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, ⁇ -hydroxycyclohexyl
• thermal polymerization initiator examples include those which decompose by heat to generate active radicals that initiate polymerization curing, such as dicumyl peroxide, di-t-butyl peroxide, t-butyl peroxybenzoyl, t-butyl hydroperoxide, benzoyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide, di-t-butyl peroxide, and t-butylperoxy-2-ethylhexanoate.
• active radicals such as dicumyl peroxide, di-t-butyl peroxide, t-butyl peroxybenzoyl, t-butyl hydroperoxide, benzoyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide, di-t-butyl peroxide, and t-butylperoxy
• the preferable lower limit of the content of the polymerization initiator relative to 100 parts by mass of the (meth)acrylic copolymer is 0.1 parts by mass.
• the content of the polymerization initiator is 0.1 parts by mass or more, the pressure-sensitive adhesive composition of the present invention can be sufficiently cured when cured, so that the pressure-sensitive adhesive composition of the present invention has better peeling performance.
• the more preferable lower limit of the content of the polymerization initiator is 0.5 parts by mass, and the even more preferable lower limit is 1 part by mass.
• the upper limit of the content of the polymerization initiator is not particularly limited, but from the viewpoint of poor appearance caused by precipitation of the polymerization initiator, the upper limit of the content of the polymerization initiator relative to 100 parts by mass of the (meth)acrylic copolymer is preferably 20 parts by mass, more preferably 15 parts by mass, and even more preferably 10 parts by mass.
• the pressure-sensitive adhesive composition of the present invention preferably further contains an inorganic filler.
• an inorganic filler in the pressure-sensitive adhesive composition of the present invention, the cohesive strength of the pressure-sensitive adhesive composition of the present invention becomes greater. Therefore, even if additives having 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.
• the tensile strength of the pressure-sensitive adhesive composition of the present invention is significantly improved, even after chemical treatment or high-temperature treatment, the pressure-sensitive adhesive composition does not break due to stress during peeling, and can be peeled more easily while suppressing the occurrence of adhesive residue. Furthermore, it can be peeled more easily from uneven surfaces while suppressing the occurrence of adhesive residue, and the peeling performance is superior.
• the inorganic filler examples include silica nanofillers such as fumed silica, fused silica, and colloidal silica, alumina nanofillers, zirconia fillers, carbon nanofillers, glass fillers, titania fillers, and zinc oxide fillers.
• silica nanofillers such as fumed silica, fused silica, and colloidal silica
• alumina nanofillers such as fumed silica, fused silica, and colloidal silica
• alumina nanofillers such as fumed silica, fused silica, and colloidal silica
• alumina nanofillers such as fumed silica, fused silica, and colloidal silica
• zirconia fillers such as fused silica
• carbon nanofillers such as fumed silica, fused silica, and colloidal silica
• alumina nanofillers such as fumed silica, fused silica, and colloidal silica
• the inorganic filler has a preferred lower limit of 0.05 ⁇ m and a preferred upper limit of 3 ⁇ m for the average particle size.
• the inorganic filler is finely dispersed in the pressure-sensitive 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 particles of any inorganic filler using an electron microscope or an optical microscope and calculating the average particle size of each inorganic filler, or by performing laser diffraction particle size distribution measurement.
• the preferred lower limit of the content of the inorganic filler relative to 100 parts by mass of the (meth)acrylic copolymer is 1 part by mass, and the preferred upper limit is 40 parts by mass.
• the pressure-sensitive adhesive composition of the present invention preferably further contains a polyfunctional oligomer or a polyfunctional monomer.
• a polyfunctional oligomer or a polyfunctional monomer When the pressure-sensitive adhesive composition of the present invention contains the polyfunctional oligomer or the polyfunctional monomer, three-dimensional reticulation of the pressure-sensitive adhesive composition by light irradiation or heat load occurs efficiently, and the pressure-sensitive adhesive composition of the present invention has better peelability.
• the term "polyfunctional oligomer or polyfunctional monomer” refers to a compound having two or more functional groups having a carbon-carbon unsaturated bond in the molecule and having a weight average molecular weight of 50,000 or less.
• the carbon-carbon unsaturated bond of the "functional group having a carbon-carbon unsaturated bond" possessed by the polyfunctional oligomer or polyfunctional monomer does not include a carbon-carbon double bond constituting an aromatic ring.
• the weight average molecular weight of the polyfunctional oligomer or polyfunctional monomer can be determined by GPC measurement in the same manner as the weight average molecular weight of the acrylic copolymer described above.
• Examples of the functional group having a carbon-carbon unsaturated bond include a vinyl group, a (meth)acryloyl group, an allyl group, and a maleimide group.
• a vinyl group is preferred from the viewpoint of a fast reaction rate with light or heat.
• polyfunctional oligomer or polyfunctional monomer examples include (meth)acrylates having a functional group with a carbon-carbon unsaturated bond, (meth)acrylic copolymers obtained by copolymerizing (meth)acrylates having a functional group with a carbon-carbon unsaturated bond (excluding those having a structural unit derived from n-heptyl (meth)acrylate and containing a carbon-carbon double bond in the side chain), silicone compounds having a functional group with a carbon-carbon unsaturated bond, and fluorine compounds having a functional group with a carbon-carbon unsaturated bond.
• the pressure-sensitive adhesive composition of the present invention contains the above-mentioned (meth)acrylate having a functional group with a carbon-carbon unsaturated bond and a (meth)acrylic copolymer obtained by copolymerizing the above-mentioned (meth)acrylate having a functional group with a carbon-carbon unsaturated bond, so that the pressure-sensitive adhesive composition of the present invention has improved photocurability and heat curability, and the pressure-sensitive adhesive composition of the present invention has superior peeling performance.
• the preferable lower limit of the number of functional groups having the carbon-carbon unsaturated bond is 2 and the preferable upper limit is 20, from the viewpoint of more efficient three-dimensional reticulation of the pressure-sensitive adhesive layer by heating or light irradiation.
• Examples of the (meth)acrylate having a functional group having a carbon-carbon unsaturated bond and the (meth)acrylic copolymer obtained by copolymerizing the (meth)acrylate 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, dipentaerythritol hexa(meth)acrylate 1,4-butyl acrylate, and the like.
• Examples of the (meth)acrylate include ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol diacrylate, oligoester acrylates such as EBECRYL524 and EBECRYL436 (all manufactured by Daicel-Allnex Corporation), urethane acrylates such as UN-5500, UN-5590 (all manufactured by Negami Chemical Industrial Co., Ltd.) and UA-160TM and UA-122P (all manufactured by Shin-Nakamura Chemical Co., Ltd.), and (meth)acrylic copolymers obtained by copolymerizing these (meth)acrylates.
• oligoester acrylates such as EBECRYL524 and EBECRYL436 (all manufactured by Daicel-Allnex Corporation)
• urethane acrylates such as UN-5500, UN-5590 (all manufactured by Negami Chemical Industrial
• these (meth)acrylates having a carbon-carbon unsaturated bond and (meth)acrylic copolymers obtained by copolymerizing (meth)acrylates having a carbon-carbon unsaturated bond may be used alone or in combination of two or more kinds.
• the pressure-sensitive adhesive composition of the present invention contains a silicone compound having a functional group with a carbon-carbon unsaturated bond and a fluorine compound having a functional group with a carbon-carbon unsaturated bond, and the silicone compound or fluorine compound bleeds out to the adherend interface, making it easier to peel while suppressing the occurrence of adhesive residue.
• the pressure-sensitive adhesive composition of the present invention may contain both a silicone compound having a functional group with a carbon-carbon unsaturated bond and a fluorine compound having a functional group with a carbon-carbon unsaturated bond.
• the silicone compound having a carbon-carbon unsaturated bond or the fluorine compound having a carbon-carbon unsaturated bond preferably further has a functional group capable of crosslinking with the (meth)acrylic copolymer.
• the silicone compound having a functional group having a carbon-carbon unsaturated bond or the fluorine compound having a functional group having a carbon-carbon unsaturated bond has a functional group capable of crosslinking with the (meth)acrylic copolymer, and thus reacts more efficiently with the (meth)acrylic copolymer by using a crosslinking agent or by irradiating with light. This makes it easier to be incorporated into the (meth)acrylic copolymer, and contamination caused by the silicone compound or fluorine compound adhering to the adherend is further suppressed.
• the functional group capable of crosslinking with the (meth)acrylic copolymer is appropriately selected depending on the functional group contained in the (meth)acrylic copolymer, and examples thereof include a carboxy group, a hydroxyl group, an amide group, an isocyanate group, and an epoxy group.
• the preferred lower limit of the total number of the functional group having the carbon-carbon unsaturated bond and the functional group capable of crosslinking with the (meth)acrylic copolymer in the silicone compound having a functional group having a carbon-carbon unsaturated bond or in the fluorine compound having a functional group having a carbon-carbon unsaturated bond is 2, and the preferred upper limit is 12.
• the three-dimensional reticulation of the pressure-sensitive adhesive composition of the present invention by light irradiation or heating is more efficiently performed.
• the more preferred upper limit of the total number of the functional group having the carbon-carbon unsaturated bond and the functional group capable of crosslinking with the (meth)acrylic copolymer is 4, and the most preferred total number of the functional group having the carbon-carbon unsaturated bond and the functional group capable of crosslinking with the (meth)acrylic copolymer is 2.
• silicone compound having a functional group having a carbon-carbon unsaturated bond examples include silicone (meth)acrylate, silicone di(meth)acrylate, and (meth)acrylic copolymers obtained by copolymerizing these (excluding those having n-heptyl (meth)acrylate as a constituent unit and containing a carbon-carbon double bond in the side chain).
• silicone compounds having a functional group having a carbon-carbon unsaturated bond commercially available ones 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.), EBECRYL350, EBECRYL1360 (all manufactured by Daicel Allnex Corporation), AC-SQ TA-100, AC-SQ SI-20 (both manufactured by Toagosei Co., Ltd.) and other silicone compounds having an acryloyl group.
• silicone compounds having a methacryloyl group such as X-22-164, X-22-164
• fluorine compound having a carbon-carbon unsaturated bond examples include a (meth)acrylic copolymer having a structural unit derived from a fluoro(meth)acrylate (excluding those having n-heptyl(meth)acrylate as a structural unit and containing a carbon-carbon double bond in a side chain).
• fluoro(meth)acrylate examples include methyl-2-fluoroacrylate, 2-(perfluorobutyl)ethyl acrylate, and the like.
• the preferred lower limit of the content of the polyfunctional oligomer or polyfunctional monomer relative to 100 parts by mass of the (meth)acrylic copolymer is 1 part by mass, and the preferred upper limit is 50 parts by mass.
• the pressure-sensitive adhesive composition of the present invention has better peeling performance.
• the more preferred lower limit of the content of the polyfunctional oligomer or polyfunctional monomer is 2 parts by mass, and the more preferred upper limit is 40 parts by mass.
• the pressure-sensitive adhesive composition of the present invention preferably further contains a gas generating agent.
• gas can be generated on the adhesive surface by light irradiation or heating, and the pressure-sensitive adhesive composition of the present invention has superior peeling performance.
• the gas generating agent is not particularly limited, and a gas generating agent that generates gas by light (e.g., ultraviolet light, laser light, etc.), heat, electromagnetic waves, electron beams, etc. is preferred. Among them, from the viewpoint of enhancing adhesion of the pressure-sensitive adhesive composition of the present invention at high temperatures and suppressing outgassing, a gas generating agent that generates gas by light is preferred.
• the gas generating agent is not particularly limited, and for example, an azo compound, an azide compound, a carboxylic acid compound, a tetrazole compound, etc. are preferably used.
• the above azo compounds include, for example, 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], 2-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2'-azobis(N-butyl-2-methylpropionamide), 2,2'-azobis(N-cyclohexyl-2-methylpropionamide), 2,2'-azobis[2-(5-methyl-2-imidazoline-2-yl)propane]dihydrochloride, 2,2'-azobis[2-(2-imidazoline-2-yl)propane]dihydrochloride, 2,2'-azobis[2-(2-imidazo
• azide compound examples include polymers having an azide group, such as 3-azidomethyl-3-methyloxetane, terephthalazide, p-tert-butylbenzazide, and glycidyl azide polymer obtained by ring-opening polymerization of 3-azidomethyl-3-methyloxetane.
• azide group such as 3-azidomethyl-3-methyloxetane, terephthalazide, p-tert-butylbenzazide, and glycidyl azide polymer obtained by ring-opening polymerization of 3-azidomethyl-3-methyloxetane.
• carboxylic acid compound examples include phenylacetic acid, diphenylacetic acid, triphenylacetic acid, and salts thereof.
• tetrazole compound examples include 1H-tetrazole, 5-phenyl-1H-tetrazole, 5,5-azobis-1H-tetrazole, or salts thereof.
• the preferred lower limit of the content of the gas generating agent relative to 100 parts by mass of the (meth)acrylic copolymer is 5 parts by mass, and the preferred upper limit is 50 parts by mass.
• the content of the gas generating agent is 5 parts by mass or more, a gas capable of sufficiently peeling off the pressure-sensitive adhesive composition of the present invention can be generated from the gas generating agent.
• the content of the gas generating agent is 50 parts by mass or less, the compatibility between the gas generating agent and other components in the pressure-sensitive adhesive composition of the present invention is excellent, and the pressure-sensitive adhesive composition of the present invention has sufficient initial adhesive strength.
• a more preferred lower limit of the content of the gas generating agent is 10 parts by mass, and a more preferred upper limit is 30 parts by mass.
• the adhesive composition of the present invention preferably further contains a tackifier.
• a tackifier By containing a tackifier, the adhesive composition of the present invention has sufficient initial adhesive strength.
• tackifiers examples 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 alone or in combination of two or more kinds.
• the preferred lower limit of the content of the tackifier relative to 100 parts by mass of the (meth)acrylic copolymer is 5 parts by mass, and the preferred upper limit is 60 parts by mass.
• the adhesive composition of the present invention has sufficient initial adhesive strength.
• the adhesive composition of the present invention does not have too high adhesive strength, and has excellent peeling performance.
• the pressure-sensitive adhesive composition of the present invention preferably contains a crosslinking agent.
• the pressure-sensitive adhesive composition of the present invention contains a crosslinking agent, the polar functional group derived from the constituent unit derived from the polar functional group-containing monomer reacts with the crosslinking agent, resulting in a significant decrease in adhesive strength. As a result, the pressure-sensitive adhesive composition of the present invention has superior peeling performance.
• crosslinking agent examples include isocyanate-based crosslinking agents, aziridine-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-type crosslinking agents, etc.
• isocyanate-based crosslinking agents are preferred because they have a fast reaction rate and further increase the cohesive strength of the pressure-sensitive adhesive composition of the present invention.
• the preferred lower limit of the content of the crosslinking agent relative to 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.
• the pressure-sensitive adhesive composition of the present invention may further contain known additives such as plasticizers, surfactants, and waxes. These additives may be used alone or in combination of two or more kinds.
• the method for producing the pressure-sensitive adhesive composition of the present invention includes, for example, a method of 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.
• the present invention also includes an adhesive tape having an adhesive layer containing the adhesive composition of the present invention.
• the pressure-sensitive adhesive tape of the present invention can achieve both excellent embedding properties for unevenness and excellent peeling performance.
• the thickness of the adhesive layer is not particularly limited, but a preferred lower limit is 5 ⁇ m and a preferred upper limit is 300 ⁇ m. When the thickness of the adhesive layer is within the above range, the adhesive layer has better flexibility, and the adhesive tape of the present invention can achieve both better embedding properties for unevenness and better peeling performance.
• a more preferred lower limit of the thickness of the adhesive layer is 20 ⁇ m, a more preferred upper limit is 200 ⁇ m, an even more preferred lower limit is 35 ⁇ m, and an even more preferred upper limit is 150 ⁇ m.
• the preferred lower limit of the content of bio-derived carbon in the pressure-sensitive adhesive layer is 10%.
• the pressure-sensitive adhesive tape of the present invention is excellent in terms of saving petroleum resources and reducing carbon dioxide emissions, and can further reduce the environmental load.
• the more preferred lower limit of the content of bio-derived carbon in the pressure-sensitive adhesive layer is 25%, and the even more preferred lower limit is 40%.
• the upper limit of the content of biological carbon in the pressure-sensitive adhesive layer is not particularly limited, and may be 100%. Note that while carbon derived from living organisms contains a certain percentage of radioactive isotope (C-14), petroleum-derived carbon contains almost no C-14. Therefore, the content of carbon derived from living organisms can be calculated by measuring the concentration of C-14 contained in the pressure-sensitive adhesive layer. Specifically, it can be measured in accordance with ASTM D6866-22, a standard used in many bioplastic industries.
• the preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer is 10% by mass, and the preferred upper limit is 90% by mass.
• the gel fraction of the pressure-sensitive adhesive layer is 10% by mass or more, the embedding ability of the pressure-sensitive adhesive tape of the present invention into the unevenness is further improved.
• the pressure-sensitive adhesive composition of the present invention has sufficient initial adhesive strength.
• the more preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer is 20% by mass, and the more preferred upper limit is 80% by mass, and the even more preferred lower limit is 30% by mass, and the even more preferred upper limit is 70% by mass.
• the gel fraction of the pressure-sensitive adhesive layer can be measured by the following method.
• the preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer after heating at 150° C. for 1 hour or after irradiating light having a wavelength in the range of 280 nm to 405 nm with an integrated light amount of 1000 mJ/cm 2 or more (hereinafter, also referred to as the “gel fraction of the pressure-sensitive adhesive layer after curing”) is 90% by mass.
• the pressure-sensitive adhesive tape of the present invention has superior peeling performance.
• the more preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer after curing is 92% by mass, and the even more preferred lower limit is 95% by mass.
• the gel fraction of the pressure-sensitive adhesive layer after curing can be measured by heating at 150° C. for 1 hour or by irradiating the pressure-sensitive adhesive layer with light having a wavelength in the range of 280 nm or more and 405 nm or less so that the integrated light amount is 1000 mJ/ cm2 or more, and then measuring the gel fraction in the same manner as the gel fraction of the pressure-sensitive adhesive layer described above.
• the upper limit of the shear storage modulus of the pressure-sensitive adhesive layer at 23° C. is preferably 1.2 ⁇ 10 5 Pa.
• the upper limit of the shear storage modulus of the pressure-sensitive adhesive layer at 23° C. is more preferably 1.1 ⁇ 10 5 Pa, and even more preferably 1.0 ⁇ 10 5 Pa.
• the shear storage modulus of the pressure-sensitive adhesive layer at 23°C can be measured, for example, by performing dynamic viscoelasticity measurement using a viscoelasticity spectrometer (manufactured by IT Measurement & Control Co., Ltd., "DVA-200") under conditions of a shear direction, a frequency of 10 Hz, a heating rate of 10°C/min, and a temperature range of -50°C to 300°C.
• a viscoelasticity spectrometer manufactured by IT Measurement & Control Co., Ltd., "DVA-200
• the pressure-sensitive adhesive layers are laminated to form a pressure-sensitive adhesive layer for measurement having a thickness of 200 ⁇ m or more.
• the shear storage modulus of the obtained pressure-sensitive adhesive layer for measurement is measured as described above.
• the preferred lower limit of the tensile storage modulus at 23°C of the pressure-sensitive adhesive layer after heating at 150°C for 1 hour or after irradiating light having a wavelength in the range of 280 nm to 405 nm with an integrated light amount of 1000 mJ/cm2 or more (hereinafter also referred to as "tensile storage modulus at 23°C after curing of the pressure-sensitive adhesive layer”) is 1.0 x 106 Pa.
• the pressure-sensitive adhesive tape of the present invention has better peeling performance.
• the more preferred lower limit of the tensile storage modulus at 23°C of the pressure-sensitive adhesive layer after curing is 5.0 x 106 Pa, and the even more preferred lower limit is 1.0 x 107 Pa.
• the preferred upper limit of the tensile storage modulus at 23° C. after curing of the pressure-sensitive adhesive layer is not particularly limited, but is preferably about 4.0 ⁇ 10 7 Pa.
• the tensile storage modulus at 23°C after curing of the pressure-sensitive adhesive layer is measured by heating at 150°C for 1 hour or irradiating light having a wavelength in the range of 280 nm to 405 nm so that the integrated light amount is 1000 mJ/ cm2 or more to cure the pressure-sensitive adhesive layer, and then measuring the dynamic viscoelasticity using a viscoelasticity spectrometer (manufactured by IT Measurement & Control Co., Ltd., "DVA-200”) under conditions of a tensile direction, a frequency of 10 Hz, a heating rate of 10°C/min, and a temperature range of -5°C to 300°C.
• a viscoelasticity spectrometer manufactured by IT Measurement & Control Co., Ltd., "DVA-200
• the pressure-sensitive adhesive layers are laminated to form a pressure-sensitive adhesive layer for measurement having a thickness of 400 ⁇ m or more.
• the tensile storage modulus of the obtained pressure-sensitive adhesive layer for measurement is measured as described above.
• the adhesive layer for measuring the shear storage modulus at 23°C of the adhesive layer and the tensile storage modulus at 23°C after the adhesive layer is cured is prepared by removing the substrate from the adhesive tape and preparing an adhesive layer for measurement using the adhesive layer from which only the adhesive layer is separated, and then performing the measurement.
• the method for removing the substrate is not particularly limited as long as it avoids treatment using a solvent, treatment involving a chemical reaction, treatment at a high temperature, etc., in order to avoid denaturation of the adhesive layer.
• the adhesive layer for measurement may be prepared using a sheet consisting of only the adhesive layer prepared separately.
• the method for adjusting the gel fraction of the pressure-sensitive adhesive layer, the gel fraction after curing of the pressure-sensitive adhesive layer, the shear storage modulus of the pressure-sensitive adhesive layer at 23°C, and the tensile storage modulus of the pressure-sensitive adhesive layer at 23°C after curing to the above ranges is not particularly limited, and examples include methods for 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, etc.
• the adhesive tape of the present invention may be a non-support tape that does not have a substrate, or a support tape that has a substrate.
• the adhesive tape of the present invention is a support tape having a substrate
• it may be a single-sided adhesive tape having the above-mentioned adhesive layer on one side of the substrate, or a double-sided adhesive tape having the above-mentioned adhesive layers on both sides of the substrate.
• the substrate is not particularly limited, but is preferably one that transmits or passes light
• examples of the substrate 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 polyether ether ketone, sheets with a mesh structure, and sheets with holes.
• the biological substrate examples include films and nonwoven fabrics containing polyesters (PES) such as plant-derived polyethylene terephthalate (PET), polyethylene furanoate (PEF), polylactic acid (PLA), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).
• PET plant-derived polyethylene terephthalate
• PAF polyethylene furanoate
• PLA polylactic acid
• PTT polytrimethylene terephthalate
• PBT polybutylene terephthalate
• PBS polybutylene succinate
• Other examples include films and nonwoven fabrics containing plant-derived polyethylene (PE), polypropylene (PP), polyurethane (PU), triacetyl cellulose (TAC), cellulose, and polyamide (PA).
• a substrate made from recycled resources may be used.
• methods for recycling resources include collecting 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 cleaning, decontamination, or decomposition by heating or fermentation.
• substrates using recycled resources include films and nonwoven fabrics made of PET, PBT, PE, PP, PA, etc., using raw materials made from recycled plastics that have been re-resinized.
• the collected waste may be burned and used as thermal energy for the production of substrates and their raw materials, or the oils and fats contained in the collected waste may be mixed with petroleum, fractionated, and refined, and used as raw materials.
• the thickness of the substrate is not particularly limited, but a preferred lower limit is 12 ⁇ m and a preferred upper limit is 200 ⁇ m. By having the thickness of the substrate within the above range, it is possible to obtain an adhesive tape that has high flexibility that allows it to be adhered closely to the shape of the adherend while also having appropriate stiffness and excellent handleability. A more preferred lower limit of the thickness of the substrate is 25 ⁇ m and a more preferred upper limit is 125 ⁇ m.
• the method for producing the pressure-sensitive adhesive tape of the present invention is not particularly limited, and the tape can be produced by a conventionally known production method.
• a solution of adhesive A is prepared by adding a solvent to the (meth)acrylic copolymer and, if necessary, a crosslinking agent, etc., and this solution of adhesive A is applied to the surface of a substrate, and the solvent in the solution is completely dried and removed to form an adhesive layer A.
• a release film is superimposed on the formed adhesive layer A with its release-treated surface facing the adhesive layer A.
• a solution of adhesive B prepared in the same manner as above is applied to the release-treated surface of a release film other than the release film, and the solvent in the solution is completely dried and removed to produce a laminate film in which adhesive layer B is formed on the surface of the release film.
• the obtained laminate film is superimposed on the back surface of the substrate on which adhesive layer A is formed, with adhesive layer B facing the back surface of the substrate to produce a laminate.
• a double-sided adhesive tape having adhesive layers on both sides of the substrate and the surfaces of the adhesive layers covered with release films can be obtained.
• two sets of laminate films may be prepared in a similar manner, and these laminate films may be superimposed on both sides of a substrate with the adhesive layer of the laminate film facing the substrate to produce a laminate.
• a double-sided adhesive tape having adhesive layers on both sides of the substrate and the surface of the adhesive layer covered with a release film may be obtained.
• the preferred lower limit of the 180° peel strength of the pressure-sensitive adhesive tape of the present invention against SUS is 0.3 N/25 mm.
• the pressure-sensitive adhesive tape of the present invention has a 180° peel strength against SUS of 0.3 N/25 mm or more, the pressure-sensitive adhesive tape of the present invention has sufficient initial adhesive strength.
• the more preferred lower limit of the 180° peel strength of the pressure-sensitive adhesive tape of the present invention against SUS is 0.5 N/25 mm, and the even more preferred lower limit is 1.0 N/25 mm.
• the upper limit of the 180° peel strength of the pressure-sensitive adhesive tape of the present invention against SUS is not particularly limited, but from the viewpoint of the handleability of the pressure-sensitive adhesive tape, a preferable upper limit is about 20 N/25 mm.
• the 180° peel strength of the pressure-sensitive adhesive tape of the present invention against SUS can be measured, for example, by a method in accordance with JIS Z0237, in which a tensile test is carried out under conditions of 23° C., a peel speed of 300 mm/min and a peel angle of 180°.
• the preferred upper limit of the 180° peel strength of the adhesive tape against SUS after heating at 150° C. for 1 hour or after irradiating light having a wavelength in the range of 280 nm to 405 nm with an integrated light amount of 1000 mJ/cm 2 or more (hereinafter also referred to as the “180° peel strength of the adhesive tape against SUS after curing”) is 0.3 N/25 mm.
• the 180° peel strength of the adhesive tape against SUS after curing is 0.3 N/25 mm or less, the adhesive tape has superior peeling performance.
• the more preferred upper limit of the 180° peel strength of the adhesive tape against SUS after curing is 0.25 N/25 mm, and the even more preferred upper limit is 0.20 N/25 mm.
• the 180° peel strength from SUS after curing of the above-mentioned adhesive tape can be measured by heating the adhesive tape of the present invention at 150°C for 1 hour before conducting a tensile test, or by irradiating the adhesive tape of the present invention with light of any wavelength within the range of 280 nm or more and 405 nm or less so that the integrated light amount is 1000 mJ/ cm2 or more, thereby curing the adhesive tape of the present invention and then conducting a tensile test.
• the method for adjusting the 180° peel strength of the adhesive tape of the present invention against SUS and the 180° peel strength of the adhesive tape after curing against SUS to the above range is not particularly limited, and examples include methods for 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.
• the adhesive tape of the present invention has excellent embedding properties and peeling performance, and is therefore preferably used for the temporary fixing of objects having uneven surfaces.
• it is more preferably used for the temporary fixing of semiconductor wafers in the manufacture of electronic components, and even more preferably for the temporary fixing of bump wafers having uneven surfaces.
• the present invention also includes a method for treating a semiconductor wafer, comprising the steps of temporarily fixing a semiconductor wafer to a support using the pressure-sensitive adhesive tape of the present invention, and peeling off the pressure-sensitive adhesive tape after the pressure-sensitive adhesive layer has been cured by light or heat.
• the support examples include glass, quartz, sapphire, copper plate, organic substrate, FR4 substrate, silicon substrate, etc. Among them, those with excellent UV transmittance are preferred, and glass, quartz, and sapphire are preferred.
• the adhesive tape of the present invention can be more easily peeled off in the semiconductor wafer processing method of the present invention by irradiating the adhesive tape of the present invention after curing from the support side with laser light or UV light before peeling the adhesive tape of the present invention from the semiconductor wafer, thereby peeling off the support.
• examples of a method for curing the pressure-sensitive adhesive layer with light include a method in which light having a wavelength of 280 nm or more and 405 nm or less is irradiated so that the integrated light amount is 1000 mJ/cm 2 or more.
• methods for curing the pressure-sensitive adhesive tape of the present invention by heat include a method of heating at a temperature of 100° C. or higher and 200° C. or lower for 10 minutes to 2 hours.
• 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 for ordinary electronic components. Even in the case of a semiconductor wafer having an uneven surface on which electrodes, circuits, etc. are formed, the semiconductor wafer processing method of the present invention suppresses peeling of the adhesive tape during cleaning processes, thinning processes, dicing processes, etc., and allows the adhesive tape to be easily peeled off from the semiconductor wafer surface after hardening while suppressing the occurrence of adhesive residue.
• the present invention also includes a method for producing a semiconductor device, which comprises the steps of temporarily fixing a semiconductor wafer to a support using the pressure-sensitive adhesive tape of the present invention, and peeling off the pressure-sensitive adhesive tape after the pressure-sensitive adhesive layer has been cured by light or heat.
• the semiconductor device manufacturing method of the present invention the processing quality of the manufactured semiconductor devices can be improved even in the case of semiconductor devices having uneven surfaces, and the production yield can be improved, thereby further improving the manufacturing efficiency of semiconductor devices.
• the semiconductor device manufacturing method of the present invention can be used in semiconductor device manufacturing processes such as film formation, etching, cleaning, thinning, cutting, bumping, reflow, annealing, and ashing.
• an adhesive composition that can achieve both excellent embedding properties for unevenness and excellent peeling performance.
• an adhesive tape having an adhesive layer containing the adhesive composition.
• a method for treating a semiconductor wafer and a method for manufacturing a semiconductor device that use the adhesive tape it is possible to provide a method for treating a semiconductor wafer and a method for manufacturing a semiconductor device that use the adhesive tape.
• 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. The mixture was then separated from the undecylenic acid by distillation to obtain n-heptyl alcohol containing bio-derived carbon. n-heptyl alcohol containing bio-derived carbon was esterified with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) to prepare n-heptyl acrylate containing bio-derived carbon.
• Example 1 Preparation of (meth)acrylic copolymer A reactor equipped with a thermometer, a stirrer, and a cooling tube was prepared, and 78.2 parts by mass of n-heptyl acrylate containing carbon derived from a living organism prepared as a (meth)acrylic acid alkyl ester by the above-mentioned method, 19.8 parts by mass of 2-hydroxyethyl acrylate as a functional group-containing monomer, 1.0 parts by mass of acrylic acid, and 80 parts by mass of ethyl acetate were added into the reactor, and the reactor was heated to start reflux.
• the hydroxyl value and acid value of the (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 a measuring instrument, a Showa Denko “GPC KF-806L” as a column, and ethyl acetate as a solvent under conditions of a sample flow rate of 1 mL/min and a column temperature of 40° C., and the weight average molecular weight was 900,000.
• the obtained ethyl acetate solution of the pressure-sensitive adhesive composition was applied with a doctor knife onto a release-treated surface of a 50 ⁇ m-thick polyethylene terephthalate (PET) film that had been subjected to a release treatment so that the thickness of the pressure-sensitive adhesive layer after drying would be 30 ⁇ m, and then the applied adhesive layer was formed by drying for 5 minutes at 110° C. Thereafter, the obtained pressure-sensitive adhesive layer was attached to a 25 ⁇ m-thick polyethylene naphthalate (PEN) film substrate, and left to stand at 40° C. for 5 days for curing, to obtain a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on one side of the substrate.
• PET polyethylene terephthalate
• PEN polyethylene naphthalate
• the adhesive layer of the obtained adhesive tape for measuring shear storage modulus was stacked to a thickness of 400 ⁇ m or more to prepare an evaluation sample.
• the dynamic viscoelasticity spectrum of the evaluation sample was measured using a viscoelasticity spectrometer (manufactured by IT Measurement & Control Co., Ltd., "DVA-200") under conditions of a simple heating mode with a heating rate of 10°C/min, a shear direction, a frequency of 10 Hz, and a temperature range of -50°C to 300. From this, the shear storage modulus (Pa) of the pressure-sensitive adhesive layer at 23°C was determined. The results are shown in Table 2.
• the prepared evaluation samples were subjected to dynamic viscoelasticity spectrum measurement using a viscoelasticity spectrometer (manufactured by IT Measurement & Control Co., Ltd., "DVA-200") under conditions of a temperature rise rate of 10°C/min, tensile direction, frequency of 10 Hz, and temperature range of -50°C to 300°C in a simple temperature rise mode. From this, the tensile storage modulus (Pa) at 23°C after curing of the pressure-sensitive adhesive layer was determined. The results are shown in Table 2.
• the obtained test sample was subjected to a tensile test in accordance with JIS Z0237 under conditions of 23°C, 50% RH, a tensile speed of 300 mm/min, and a peel angle of 180°, and the 180° peeling force (N/25 mm) of the adhesive tape against SUS was measured.
• the results are shown in Table 2.
• the obtained adhesive tape was cut into a circle with a diameter of 20 cm, and attached in a vacuum to the stepped side of a silicon wafer with a diameter of 20 cm, a thickness of about 750 ⁇ m, and a step of about 10 ⁇ m, and then left to stand for 1 hour under conditions of 23° C. and 50% RH to prepare a measurement sample.
• the stepped silicon wafer was prepared by making a cut of about 10 ⁇ m in the surface of a wafer ( ⁇ 8 inches, thickness 725 ⁇ m) using a dicing device (DISCO Corporation, “DFD6360”).
• the wafer surface of the measurement sample was observed with an optical microscope (Keyence Corporation, "VHX-970F", magnification 10x), and the embedding ability of the adhesive tape into the irregularities (embedding ability of the irregularities) was evaluated according to the following criteria.
• ⁇ No gap was found between the wafer and the adhesive tape.
• ⁇ The size of the gap between the wafer and the adhesive tape was less than 5% of the total area of the adhesive surface.
• ⁇ The size of the gap between the wafer and the adhesive tape was 5% or more of the total area of the adhesive surface.
• the obtained adhesive tape was cut into a circle having a diameter of 20 cm, and attached in a vacuum to the stepped surface of a stepped silicon wafer having a circuit (unevenness) with a diameter of 20 cm, a thickness of about 750 ⁇ m, and a step of about 10 ⁇ m, which was prepared in the same manner as in the above-mentioned "(Unevenness embedding ability)". Furthermore, the non-stepped surface of the stepped silicon wafer to which the adhesive tape was attached was subjected to grinding and polishing, and the thickness of the stepped silicon wafer was ground to 50 ⁇ m, to prepare a measurement sample.
• the adhesive tape of the measurement sample was cured by irradiating it with light of 405 nm wavelength so that the cumulative light amount was 2500 mJ/ cm2 , and the cured adhesive tape was peeled off with a peeling tape, and the wafer crack of the stepped silicon wafer from which the adhesive tape was peeled off was visually observed.
• the same operation was performed for five measurement samples, and the peeling performance of the adhesive tape was evaluated according to the following criteria. ⁇ : 0 out of 5 silicon wafers had a cracked step. ⁇ : 1 out of 5 silicon wafers had a cracked step. ⁇ : 2 or more out of 5 silicon wafers had a cracked step.
• Examples 2 to 12 and 14 to 17, Comparative Examples 1 to 5 Except for changing the composition as shown in Table 1 in the above-mentioned "(1) Preparation of (meth)acrylic copolymer", and changing the composition of the adhesive composition as shown in Tables 2 to 4 in the above-mentioned "(2) Production of adhesive composition and adhesive tape", the preparation of the (meth)acrylic copolymer, the production of the adhesive composition and the adhesive tape were performed in the same manner as in Example 1, and the (meth)acrylic copolymer, the adhesive layer and the adhesive tape were measured and evaluated in the same manner as in Example 1. The results are shown in Tables 1 to 4.
• Example 13 Except for the fact that in the above-mentioned "(1) Preparation of (meth)acrylic copolymer", the composition was changed as shown in Table 1, and in the above-mentioned "(2) Production of adhesive composition and adhesive tape", the composition of the adhesive composition was changed as shown in Table 3 and the substrate was changed from a 25 ⁇ m-thick PEN film to a 25 ⁇ m-thick PET film, the (meth)acrylic copolymer was prepared, and the adhesive composition and adhesive tape were produced 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.
• an adhesive composition that can achieve both excellent embedding properties for unevenness and excellent peeling performance.
• an adhesive tape having an adhesive layer containing the adhesive composition.
• a method for treating a semiconductor wafer and a method for manufacturing a semiconductor device that use the adhesive tape it is possible to provide a method for treating a semiconductor wafer and a method for manufacturing a semiconductor device that use the adhesive tape.

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