WO2025028650A1 - アクリル系粘着剤組成物、粘着剤、粘着テープ、粘着テープの製造方法、及び、アクリル系共重合体の製造方法 - Google Patents

アクリル系粘着剤組成物、粘着剤、粘着テープ、粘着テープの製造方法、及び、アクリル系共重合体の製造方法 Download PDF

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WO2025028650A1
WO2025028650A1 PCT/JP2024/027694 JP2024027694W WO2025028650A1 WO 2025028650 A1 WO2025028650 A1 WO 2025028650A1 JP 2024027694 W JP2024027694 W JP 2024027694W WO 2025028650 A1 WO2025028650 A1 WO 2025028650A1
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Prior art keywords
acrylic
sensitive adhesive
solvent
adhesive composition
mass
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English (en)
French (fr)
Japanese (ja)
Inventor
雄大 緒方
渚 緒方
知浩 肥田
大三 伊井
智基 戸田
大輔 濱▲崎▼
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Sekisui Chemical Co Ltd
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Sekisui Chemical Co Ltd
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Priority to KR1020257035233A priority Critical patent/KR20260047177A/ko
Priority to JP2024556009A priority patent/JPWO2025028650A1/ja
Priority to CN202480022605.2A priority patent/CN120897972A/zh
Publication of WO2025028650A1 publication Critical patent/WO2025028650A1/ja
Anticipated expiration legal-status Critical
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • 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
    • 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
    • C09J11/08—Macromolecular additives
    • 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
    • C09J123/00—Adhesives based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Adhesives based on derivatives of such polymers
    • 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
    • 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
    • C09J133/02—Homopolymers or copolymers of acids; Metal or ammonium salts thereof
    • 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
    • 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
    • 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
    • C09J133/14—Homopolymers or copolymers of esters of esters containing halogen, nitrogen, sulfur or oxygen atoms in addition to the carboxy oxygen
    • 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
    • C09J151/00—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
    • 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
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • 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
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C09J7/24—Plastics; Metallised plastics based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
    • 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]

Definitions

  • Adhesive tapes having an adhesive layer containing an adhesive have been widely used to fasten components in electronic components, vehicles, houses, and building materials (e.g., 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.
  • Acrylic adhesives containing acrylic copolymers are widely used as adhesives with excellent adhesive strength.
  • monomers other than acrylate may be copolymerized as constituent monomers of the acrylic copolymer.
  • an acrylic adhesive containing an acrylic copolymer copolymerized with such a monomer other than acrylate it is difficult to apply uniformly, and it may be difficult to manufacture an adhesive tape having an adhesive layer or to attach an adherend using a liquid adhesive.
  • an adhesive tape having an adhesive layer manufactured by applying an acrylic adhesive composition may have lines or streaks in the adhesive layer, resulting in poor appearance. Therefore, it is an issue to obtain an acrylic pressure-sensitive adhesive composition that has excellent coatability and is capable of exerting high adhesive strength.
  • the present invention aims to provide an acrylic adhesive composition that has excellent coatability, can be applied without lines or streaks, and can exert high adhesive strength.
  • the present invention also aims to provide an adhesive and an adhesive tape formed from the acrylic adhesive composition.
  • the present invention aims to provide an adhesive tape that is free from lines or streaks and has a good appearance.
  • the present invention also aims to provide a method for producing an adhesive tape formed from the acrylic adhesive composition.
  • the present invention also aims to provide a method for producing an acrylic copolymer that can be used for an acrylic adhesive composition that has excellent coatability, can be applied without lines or streaks, and can exert high adhesive strength.
  • Disclosure 1 relates to an acrylic pressure-sensitive adhesive composition containing an acrylic copolymer and a solvent, wherein the acrylic copolymer has a constituent unit derived from an alkyl (meth)acrylate ester and a constituent unit derived from an olefin polymer having a terminal polymerizable unsaturated double bond, the solvent contains at least one solvent selected from the group consisting of hydrocarbon solvents and solvents having an SP value of 7.2 (J/cm 3 ) 1/2 or more and 8.6 (J/cm 3 ) 1/2 or less, and the acrylic pressure-sensitive adhesive composition has a solid content of 15 mass % or more and 50 mass % or less.
  • the acrylic copolymer has a constituent unit derived from an alkyl (meth)acrylate ester and a constituent unit derived from an olefin polymer having a terminal polymerizable unsaturated double bond
  • the solvent contains at least one solvent selected from the group consisting of hydrocarbon solvents and solvents having an SP value of 7.2 (J
  • the present disclosure 2 is the acrylic pressure-sensitive adhesive composition of the present disclosure 1, wherein the solvent comprises a hydrocarbon-based solvent, and the hydrocarbon-based solvent comprises an aliphatic hydrocarbon-based solvent.
  • the present disclosure 3 is the acrylic pressure-sensitive adhesive composition according to the present disclosure 2, wherein the aliphatic hydrocarbon solvent contains an aliphatic hydrocarbon compound having 6 to 9 carbon atoms.
  • the present disclosure 4 relates to the acrylic pressure-sensitive adhesive composition of the present disclosure 3, wherein the aliphatic hydrocarbon compound having 6 to 9 carbon atoms comprises at least one selected from the group consisting of normal hexane, cyclohexane, and methylcyclohexane.
  • the present disclosure 5 is the acrylic pressure-sensitive adhesive composition of the present disclosure 1 , 2, 3 , or 4 , wherein the solvent further comprises at least one solvent selected from the group consisting of ester solvents and solvents having an SP value of more than 8.6 (J/cm 3 ) 1/2 and not more than 9.0 (J/cm 3 ) 1/2.
  • the present disclosure 6 relates to the acrylic pressure-sensitive adhesive composition of the present disclosure 5, wherein the solvent includes an ester-based solvent, the ester-based solvent includes an ester compound represented by the following formula (1), and a content ratio of the hydrocarbon-based solvent in a total content of the hydrocarbon-based solvent and the ester-based solvent is 5.0 mass% or more and less than 100 mass%:
  • the present disclosure 7 is the acrylic pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, 5, or 6, wherein the hydrocarbon solvent does not contain an aromatic hydrocarbon solvent, or the hydrocarbon solvent contains an aromatic hydrocarbon solvent and a content of the aromatic hydrocarbon solvent in the solvent is 1000 ppm or less.
  • the present disclosure 8 is the acrylic pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, 5, 6, or 7, wherein the structural unit derived from the (meth)acrylic acid alkyl ester contains a structural unit derived from a (meth)acrylic acid alkyl ester having an alkyl group derived from an alcohol having 1 or more and 4 or less carbon atoms.
  • the present disclosure 9 is the acrylic pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, 5, 6, 7, or 8, wherein the content of the structural units derived from the (meth)acrylic acid alkyl ester in the acrylic copolymer is 50% by mass or more and 99% by mass or less.
  • the present disclosure 10 is the acrylic pressure-sensitive adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, or 9, wherein the content of the structural unit derived from the olefin polymer having a terminal polymerizable unsaturated double bond in the acrylic copolymer is 5.0 mass% or more.
  • the present disclosure 11 is the acrylic pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein the acrylic copolymer has a constituent unit derived from a polar functional group-containing monomer.
  • the present disclosure 12 is the acrylic pressure-sensitive adhesive composition of the present disclosure 11, wherein the constituent unit derived from the polar functional group-containing monomer includes at least one selected from the group consisting of a constituent unit derived from a carboxy group-containing monomer and a constituent unit derived from a hydroxyl group-containing monomer.
  • the present disclosure 13 is the acrylic pressure-sensitive adhesive composition according to the present disclosure 11 or 12, wherein the total content of constituent units derived from polar functional group-containing monomers in the acrylic copolymer is 0.1 mass% or more and 20 mass% or less.
  • the present disclosure 14 is the acrylic pressure-sensitive adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13, which contains a tackifier resin.
  • the present disclosure 15 is the acrylic pressure-sensitive adhesive composition of the present disclosure 14, wherein the tackifier resin comprises a high hydroxyl value tackifier resin having a hydroxyl value of 15 mgKOH/g or more.
  • the present disclosure 16 is the acrylic pressure-sensitive adhesive composition according to the present disclosure 14 or 15, wherein the content of the tackifier resin is 40 parts by mass or less relative to 100 parts by mass of the acrylic copolymer.
  • the present disclosure 17 is an acrylic pressure-sensitive adhesive composition according to the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16, which contains a crosslinking agent.
  • the present disclosure 18 is a pressure-sensitive adhesive formed from the acrylic pressure-sensitive adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17.
  • the present disclosure 19 is a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17.
  • Disclosure 20 is a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer formed using an acrylic pressure-sensitive adhesive composition, the acrylic pressure-sensitive adhesive composition containing an acrylic copolymer, the acrylic copolymer having a constituent unit derived from an alkyl (meth)acrylate ester and a constituent unit derived from an olefin polymer having a terminal polymerizable unsaturated double bond, the pressure-sensitive adhesive layer containing a solvent, the solvent including an aliphatic hydrocarbon solvent.
  • Disclosure 21 is the pressure-sensitive adhesive tape of Disclosure 20, wherein the acrylic copolymer has a constituent unit derived from a polar functional group-containing monomer.
  • the present disclosure 22 is the pressure-sensitive adhesive tape of the present disclosure 19, 20, or 21, wherein the pressure-sensitive adhesive layer does not contain an aromatic hydrocarbon-based solvent, or the pressure-sensitive adhesive layer contains an aromatic hydrocarbon-based solvent and the content of the aromatic hydrocarbon-based solvent in the pressure-sensitive adhesive layer is 300 ppm or less.
  • the present disclosure 23 is the pressure-sensitive adhesive tape of the present disclosure 19, 20, 21, or 22, wherein the pressure-sensitive adhesive layer has a gel fraction of 10 mass % or more and 70 mass % or less.
  • Disclosure 24 is a pressure-sensitive adhesive tape according to Disclosure 19, 20, 21, 22, or 23 having a substrate.
  • the present disclosure 25 is a pressure-sensitive adhesive tape according to the present disclosure 19, 20, 21, 22, 23, or 24, which is used for fixing an electronic device component or an in-vehicle component.
  • the present disclosure 26 is a method for producing a pressure-sensitive adhesive tape, comprising a step of applying the acrylic pressure-sensitive adhesive composition of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17.
  • the present disclosure 27 relates to a method for producing an acrylic copolymer, comprising: a step (i) of polymerizing a monomer mixture containing an alkyl (meth)acrylate and an olefin polymer having a terminal polymerizable unsaturated double bond in a solvent in the presence of a polymerization initiator, wherein the solvent contains a hydrocarbon solvent.
  • Disclosure 28 is the method for producing an acrylic copolymer according to Disclosure 27, wherein the hydrocarbon solvent includes an aliphatic hydrocarbon solvent.
  • Disclosure 29 is the method for producing an acrylic copolymer according to Disclosure 28, wherein the aliphatic hydrocarbon solvent contains an aliphatic hydrocarbon compound having 6 to 9 carbon atoms.
  • Disclosure 30 is the method for producing an acrylic copolymer according to Disclosure 29, wherein the aliphatic hydrocarbon compound having 6 to 9 carbon atoms includes at least one selected from the group consisting of normal hexane, cyclohexane, and methylcyclohexane.
  • the present disclosure 31 is the method for producing an acrylic copolymer according to the present disclosure 27, 28, 29, or 30, wherein the solvent further includes an ester-based solvent, and the ester-based solvent includes an ester compound represented by the following formula (1), and a blending ratio of the hydrocarbon-based solvent in a total blending amount of the hydrocarbon-based solvent and the ester-based solvent is 5.0 mass% or more and less than 100 mass%.
  • the present disclosure 32 is the method for producing an acrylic copolymer according to the present disclosure 27, 28, 29, 30, or 31, wherein the polymerization initiator contains at least one selected from the group consisting of organic peroxides and azo compounds.
  • the present disclosure 33 is the method for producing an acrylic copolymer according to the present disclosure 27, 28, 29, 30, 31 or 32, wherein the amount of the polymerization initiator is 0.01 parts by mass or more and 3.0 parts by mass or less relative to 100 parts by mass of the monomer mixture.
  • the present disclosure 34 is the method for producing an acrylic copolymer according to the present disclosure 27, 28, 29, 30, 31, 32, or 33, wherein in the step (i), the monomer mixture is polymerized in a solvent in the presence of a polymerization initiator at a temperature of 50° C. or higher and 100° C. or lower.
  • R 1 and R 2 each independently represent an aliphatic hydrocarbon group having 1 to 5 carbon atoms.
  • the adhesive tape of Disclosure 19 is also referred to as the "adhesive tape of Invention 19," and the adhesive tape of Disclosure 20 is also referred to as the “adhesive tape of Invention 20.” Furthermore, matters common to the adhesive tape of Invention 19 and the adhesive tape of Invention 20 are not particularly specified or are described as the "adhesive tape of the present invention.”
  • the present inventors have studied the acrylic copolymer contained in the acrylic pressure-sensitive adhesive composition and found that high adhesive strength can be achieved by using a copolymer having a structural unit derived from an alkyl (meth)acrylate ester and a structural unit derived from an olefin polymer having a polymerizable unsaturated double bond at the end.
  • the present inventors have also studied the solvent contained in the acrylic pressure-sensitive adhesive composition and found that the application properties of the acrylic copolymer containing an acrylic copolymer copolymerized with a low-polarity monomer other than acrylate are excellent by using a solvent having low polarity (e.g., a hydrocarbon solvent, etc.) instead of ethyl acetate, etc., which is normally used in acrylic pressure-sensitive adhesive compositions.
  • a solvent having low polarity e.g., a hydrocarbon solvent, etc.
  • an acrylic pressure-sensitive adhesive composition that has excellent application properties, can be applied without lines or streaks, and can exhibit high adhesive strength can be obtained by preparing an acrylic pressure-sensitive adhesive composition containing an acrylic copolymer capable of exhibiting high adhesive strength and a solvent having low polarity, as described above, and has completed the present invention.
  • the acrylic pressure-sensitive adhesive composition of the present invention contains an acrylic copolymer.
  • the acrylic copolymer has structural units derived from an alkyl (meth)acrylate ester.
  • (meth)acrylic means acrylic or methacrylic.
  • the structural unit derived from the (meth)acrylic acid alkyl ester preferably contains a structural unit derived from a (meth)acrylic acid alkyl ester in which the carbon number of the alkyl group derived from an alcohol is from 1 to 4.
  • a structural unit derived from a (meth)acrylic acid alkyl ester in which the carbon number of the alkyl group derived from an alcohol is from 1 to 4 the acrylic pressure-sensitive adhesive composition of the present invention can exhibit more excellent retention performance at high temperatures.
  • the term "alkyl group derived from an alcohol” refers to an alkyl group bonded to an oxygen atom of an ester bond in an alkyl (meth)acrylate.
  • Examples of the (meth)acrylic acid alkyl ester having 1 to 4 carbon atoms in the alkyl group derived from the alcohol include (meth)acrylic acid alkyl esters obtained by dehydration condensation of (meth)acrylic acid and an alcohol having a linear or branched alkyl group having 1 to 4 carbon atoms. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, etc. Among these, n-butyl (meth)acrylate is preferred.
  • These (meth)acrylic acid alkyl esters may be used alone or in combination of two or more kinds.
  • the preferred lower limit of the content of the structural units derived from the (meth)acrylic acid alkyl ester having 1 to 4 carbon atoms in the alkyl group derived from the alcohol is 50% by mass.
  • the acrylic adhesive composition of the present invention can exhibit higher adhesive strength and better retention performance.
  • a more preferred lower limit of the content of the structural units derived from the (meth)acrylic acid alkyl ester having 1 to 4 carbon atoms in the alkyl group derived from the alcohol is 60% by mass, and an even more preferred lower limit is 70% by mass.
  • the content of the structural units derived from the (meth)acrylic acid alkyl ester having 1 to 4 carbon atoms in the alkyl group derived from the alcohol is 100% by mass, that is, the structural units derived from the (meth)acrylic alkyl ester are only structural units derived from the (meth)acrylic acid alkyl ester having 1 to 4 carbon atoms in the alkyl group derived from the alcohol.
  • the structural unit derived from the (meth)acrylic acid alkyl ester may have a structural unit derived from another (meth)acrylic acid alkyl ester other than the structural unit derived from the (meth)acrylic acid alkyl ester having 1 to 4 carbon atoms in the alkyl group derived from the alcohol.
  • Examples of the other (meth)acrylic acid alkyl esters include n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, n-heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 1-methylheptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate
  • n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-heptyl (meth)acrylate, and 1-methylheptyl (meth)acrylate are preferred, and 2-ethylhexyl (meth)acrylate and n-heptyl (meth)acrylate are more preferred.
  • These (meth)acrylic acid alkyl esters may be used alone or in combination of two or more kinds.
  • the content ratio of the structural unit derived from the (meth)acrylic acid alkyl ester in the acrylic copolymer is preferably 50% by mass at the lower limit and 99% by mass at the upper limit.
  • the content ratio of the structural unit derived from the (meth)acrylic acid alkyl ester is 50% by mass or more, the performance as an adhesive is easily maintained, and the polymerization reaction during production can be efficiently promoted.
  • the content ratio of the structural unit derived from the (meth)acrylic acid alkyl ester is 99% by mass or less, the acrylic adhesive composition of the present invention is easily able to maintain the performance as an adhesive.
  • the more preferred lower limit of the content ratio of the structural unit derived from the (meth)acrylic acid alkyl ester is 60% by mass, the more preferred upper limit is 95% by mass, the even more preferred lower limit is 70% by mass, and the even more preferred upper limit is 90% by mass.
  • the acrylic copolymer has a structural unit derived from an olefin polymer having a polymerizable unsaturated double bond at the end.
  • the acrylic copolymer has a structural unit derived from an olefin polymer having a polymerizable unsaturated double bond at the end
  • the acrylic adhesive composition of the present invention forms an adhesive or adhesive layer
  • the structural units derived from the olefin polymer having a polymerizable unsaturated double bond at the end of the side chain of the acrylic copolymer aggregate by interaction with each other to form a structure in which a pseudo intermolecular crosslinking point is formed.
  • the adhesive or adhesive layer formed from the acrylic adhesive composition of the present invention exhibits hard properties like a crosslinked adhesive or adhesive layer when the strain applied to the adhesive or adhesive layer is small, and the holding power is further improved.
  • the adhesive or adhesive layer is subjected to peeling stress and the strain becomes large, the pseudo crosslinking is broken and the molecules of the acrylic copolymer are stretched, so that the adhesive or adhesive layer formed from the acrylic adhesive composition of the present invention exhibits high flexibility properties and improves adhesion.
  • the acrylic copolymer has structural units derived from an olefin polymer having a polymerizable unsaturated double bond at the end, the acrylic pressure-sensitive adhesive composition of the present invention can exhibit high adhesive strength and higher retention performance.
  • the olefin polymer having a polymerizable unsaturated double bond at the terminal may have a polymerizable unsaturated double bond at one terminal, or may have polymerizable unsaturated double bonds at both terminals.
  • an olefin polymer having a polymerizable unsaturated double bond at one terminal is preferred from the viewpoint of facilitating the formation of an appropriate number of pseudo crosslinks.
  • Examples of the olefin polymer having a polymerizable unsaturated double bond at one end include ethylene-butylene copolymers, ethylene-propylene copolymers, ethylene polymers, propylene polymers, butylene polymers, etc., each of which has a group having a polymerizable unsaturated double bond at one end or both ends.
  • These olefin polymers having a polymerizable unsaturated double bond at the terminal may be used alone or in combination of two or more kinds.
  • Examples of the group having a polymerizable unsaturated double bond include a (meth)acryloyl group, a vinyl ether group, a styryl group, etc.
  • a (meth)acryloyl group is preferred because of its excellent copolymerizability with the (meth)acrylic acid alkyl ester.
  • (meth)acryloyl means acryloyl or methacryloyl.
  • Examples of the olefin polymer having a (meth)acryloyl group at its terminal include an ethylene macromonomer having a (meth)acryloyl group at one terminal, a propylene macromonomer having a (meth)acryloyl group at one terminal, an ethylene-butylene macromonomer having a (meth)acryloyl group at one terminal, an ethylene-propylene macromonomer having a (meth)acryloyl group at one terminal, etc.
  • an ethylene-butylene macromonomer having a (meth)acryloyl group at one terminal and an ethylene-propylene macromonomer having a (meth)acryloyl group at one terminal are preferred, since the glass transition temperature of the acrylic copolymer described below is more likely to fall within an appropriate range, and the acrylic pressure-sensitive adhesive composition of the present invention is able to exhibit superior adhesive strength.
  • the term "macromonomer” refers to a monomer having a polymerizable functional group and a weight average molecular weight of about 1,000 to 100,000.
  • the content ratio of the structural unit derived from the olefin polymer having a polymerizable unsaturated double bond at the end in the acrylic copolymer is preferably 5.0% by mass at the lower limit.
  • the acrylic copolymer forms a moderate number of pseudo crosslinks, and the acrylic pressure-sensitive adhesive composition of the present invention can exhibit higher adhesive strength.
  • the content ratio of the structural unit derived from the olefin polymer having a polymerizable unsaturated double bond at the end is more preferably 10% by mass at the lower limit, and even more preferably 20% by mass at the lower limit.
  • the preferred upper limit of the content of the structural unit derived from the olefin polymer having a terminal polymerizable unsaturated double bond is 40% by mass. By making the content of the structural unit derived from the olefin polymer having a terminal polymerizable unsaturated double bond 40% by mass or less, the cohesive failure of the acrylic pressure-sensitive adhesive composition of the present invention can be further suppressed.
  • the preferred upper limit of the content of the structural unit derived from the olefin polymer having a terminal polymerizable unsaturated double bond is 35% by mass, and more preferably 30% by mass.
  • the acrylic copolymer preferably has a structural unit derived from a polar functional group-containing monomer.
  • the acrylic copolymer has a structural unit derived from a polar functional group-containing monomer, so that the polarity of the acrylic copolymer increases, so that the cohesive force of the acrylic pressure-sensitive adhesive composition of the present invention is increased and the acrylic pressure-sensitive adhesive composition of the present invention can exhibit better retention performance at high temperatures.
  • the acrylic pressure-sensitive adhesive composition of the present invention contains a crosslinking agent described below, the acrylic copolymer has a structure crosslinked via the crosslinking agent, and the acrylic pressure-sensitive adhesive composition of the present invention can exhibit better adhesion and better retention performance.
  • the polar functional group-containing monomer examples include a carboxy group-containing monomer, a hydroxyl group-containing monomer, an amide group-containing monomer, and an amino group-containing monomer.
  • the polar functional group-containing monomer preferably includes at least one selected from the group consisting of a carboxy group-containing monomer and a hydroxyl group-containing monomer. That is, the constitutional unit derived from the polar functional group-containing monomer preferably includes at least one selected from the group consisting of a constitutional unit derived from a carboxy group-containing monomer and a constitutional unit derived from a hydroxyl group-containing monomer.
  • These polar functional group-containing monomers may be used alone or in combination of two or more kinds.
  • carboxy group-containing monomer examples include unsaturated carboxylic acids such as (meth)acrylic acid, (meth)acryloyl acetic acid, (meth)acryloyl propionic acid, (meth)acryloyl butyric acid, (meth)acryloyl pentanoic acid, crotonic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, and 2-carboxyethyl (meth)acrylate.
  • unsaturated carboxylic acids such as (meth)acrylic acid, (meth)acryloyl acetic acid, (meth)acryloyl propionic acid, (meth)acryloyl butyric acid, (meth)acryloyl pentanoic acid, crotonic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, and 2-carboxyethyl (meth)acrylate.
  • hydroxyl group-containing monomer examples include 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate.
  • amide group-containing monomer examples include N-vinyl-2-pyrrolidone, N-vinylcaprolactam, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, and N-isopropyl(meth)acrylamide.
  • amino group-containing monomer examples include (meth)acryloylmorpholine, 2-dimethylaminoethyl (meth)acrylate, and 2-diethylaminoethyl (meth)acrylate.
  • the total content ratio of the constituent units derived from the polar functional group-containing monomer in the acrylic copolymer is preferably 0.1% by mass at the lower limit and 20% by mass at the upper limit.
  • the polarity of the acrylic copolymer is increased, so that the cohesive force of the acrylic pressure-sensitive adhesive composition of the present invention is increased and it is possible to exhibit better retention performance at high temperatures. In addition, the reaction during polymerization is more likely to proceed smoothly.
  • the acrylic pressure-sensitive adhesive composition of the present invention does not become too hard and can exhibit sufficient initial adhesive strength.
  • a more preferable lower limit of the total content ratio of the constituent units derived from the polar functional group-containing monomer is 1.0% by mass, a more preferable upper limit is 8.0% by mass, and an even more preferable lower limit is 3.0% by mass.
  • the acrylic copolymer may have a constituent unit derived from the alkyl (meth)acrylate ester, a constituent unit derived from the olefin polymer having a terminal polymerizable unsaturated double bond, and a constituent unit derived from the polar functional group-containing monomer, but may also have a constituent unit derived from another monomer in addition to these constituent units.
  • the weight average molecular weight (Mw) of the acrylic copolymer is preferably 500,000 at the lower limit and 2,000,000 at the upper limit.
  • Mw weight average molecular weight
  • the more preferred lower limit of the weight average molecular weight of the acrylic copolymer is 600,000, the more preferred upper limit is 1,500,000, the even more preferred lower limit is 800,000, and the even more preferred upper limit is 1,350,000.
  • the preferred lower limit of the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the acrylic copolymer is 1.0, and the preferred upper limit is 10.0.
  • the acrylic pressure-sensitive adhesive composition of the present invention can exhibit better adhesive strength and better retention performance.
  • a more preferred lower limit of the polydispersity of the acrylic copolymer is 1.5, a more preferred upper limit is 9.0, an even more preferred lower limit is 2.0, and an even more preferred upper limit is 8.0.
  • the weight average molecular weight (Mw) and number average molecular weight (Mn) refer to the weight average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC). Specifically, the acrylic copolymer is diluted to 0.1% by mass with tetrahydrofuran (THF), and the diluted solution is filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 ⁇ m).
  • GPC gel permeation chromatography
  • the obtained filtrate is supplied to a gel permeation chromatograph (Waters, "2690 Separations Module", etc.), and GPC measurement is performed under conditions of a sample flow rate of 1 mL/min and a column temperature of 40°C, and the polystyrene-equivalent molecular weight of the acrylic copolymer is measured to obtain the weight average molecular weight (Mw) and number average molecular weight (Mn).
  • Mw weight average molecular weight
  • Mn number average molecular weight
  • a GPC KF-806L (Showa Denko KK) or the like is used as the column, and for example, a differential refractometer or the like can be used as the detector.
  • the polydispersity (Mw/Mn) can be obtained by using the obtained weight average molecular weight (Mw) and number average molecular weight (Mn).
  • Methods for adjusting the weight-average molecular weight of the acrylic copolymer include, for example, changing the polymerization initiator or monomer concentration during the polymerization reaction, adding a small amount of a chain transfer agent such as dodecyl mercaptan, and changing the type of polymerization reaction solvent to control chain transfer to the solvent.
  • a chain transfer agent such as dodecyl mercaptan
  • the glass transition temperature (Tg) of the acrylic copolymer is preferably in the range of -100°C or more and 200°C or less, and more preferably -20°C or less.
  • Tg glass transition temperature
  • a more preferable upper limit of the glass transition temperature of the acrylic copolymer is -25°C, and an even more preferable upper limit is -30°C.
  • the acrylic copolymer has a plurality of glass transition temperatures, it is more preferable that all of the glass transition temperatures are -20°C or less.
  • the acrylic pressure-sensitive adhesive composition of the present invention contains a plurality of the acrylic copolymers, it is more preferable that all of the acrylic copolymers have glass transition temperatures of -20°C or less.
  • the glass transition temperature can be measured by differential scanning calorimetry. More specifically, the glass transition temperature can be measured in a nitrogen atmosphere (nitrogen flow, flow rate 50 mL/min) using a differential scanning calorimeter (manufactured by Seiko Instruments Inc., "220C” or the like) according to a method in accordance with JIS K6240:2011 under conditions of a measurement temperature of -100°C to 200°C and a temperature rise rate of 10°C/min.
  • the glass transition temperature of the acrylic copolymer can be adjusted by changing the type and content of the monomers that are the raw materials for the acrylic copolymer.
  • the content of the acrylic copolymer in the acrylic pressure-sensitive adhesive composition of the present invention is preferably 40% by mass at the lower limit.
  • the acrylic pressure-sensitive adhesive composition of the present invention can exhibit better adhesive strength.
  • the content of the acrylic copolymer is more preferably 50% by mass at the lower limit, and even more preferably 55% by mass at the lower limit.
  • the upper limit of the content of the acrylic copolymer is preferably 99.5% by mass.
  • a conventionally known method can be used in which a raw material monomer mixture is subjected to a radical reaction in the presence of a polymerization initiator, and examples of such methods include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, and bulk polymerization. Among these, solution polymerization is preferred because of its ease of synthesis.
  • reaction solvent examples include ethyl acetate, toluene, methyl ethyl ketone, methyl sulfoxide, ethanol, acetone, diethyl ether, cyclohexane, etc. These reaction solvents may be used alone or in combination of two or more.
  • Examples of the polymerization initiator 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.
  • Examples of the azo compound include azobisisobutyronitrile and azobiscyclohexanecarbonitrile. These polymerization initiators may be used alone or in combination of two or more kinds
  • the acrylic pressure-sensitive adhesive composition of the present invention contains a solvent.
  • the solvent contains at least one solvent selected from the group consisting of hydrocarbon solvents and solvents having an SP value of 7.2 (J/ cm3 ) 1/2 or more and 8.6 (J/ cm3 ) 1/2 or less.
  • the solvent contains at least one solvent selected from the group consisting of hydrocarbon solvents and solvents having an SP value of 7.2 (J/ cm3 ) 1/2 or more and 8.6 (J/ cm3 ) 1/2 or less, the coatability of the acrylic pressure-sensitive adhesive composition of the present invention is improved.
  • the "SP value” is also called the solubility parameter, and is an index capable of expressing the affinity between substances, calculated using the Fedors method (R.F. Fedors, Polym. Eng. Sci., 14(2), 147-154 (1974)).
  • the hydrocarbon solvent contains an aliphatic hydrocarbon solvent.
  • the content of volatile organic compounds (VOCs) in the solvent can be reduced, and the amount of volatile organic compounds (VOCs) remaining in the pressure-sensitive adhesive or pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition of the present invention is reduced, thereby reducing the impact on the human body.
  • the aliphatic hydrocarbon solvent preferably contains an aliphatic hydrocarbon compound having 6 to 9 carbon atoms.
  • the acrylic pressure-sensitive adhesive composition of the present invention can exhibit higher adhesive strength and better retention performance.
  • Examples of the aliphatic hydrocarbon compound having 6 to 9 carbon atoms include normal hexane, cyclohexane, methylcyclohexane, normal heptane, cycloheptane, methylcycloheptane, normal octane, cyclooctane, methylcyclooctane, normal nonane, and cyclononane.
  • the SP value of the solvent when the solvent contains a solvent having an SP value of 7.2 (J/ cm3 ) 1/2 or more and 8.6 (J/ cm3 ) 1/2 or less, the SP value of the solvent preferably has a lower limit of 7.4 (J/ cm3 ) 1/2 and a higher limit of 8.4 (J/ cm3 ) 1/2 .
  • the acrylic pressure-sensitive adhesive composition of the present invention has better coatability.
  • the lower limit of the SP value of the solvent is more preferably 7.6 (J/ cm3 ) 1/2 and the higher limit is more preferably 8.2 (J/ cm3 ) 1/2 .
  • solvents having an SP value of 7.2 (J/cm 3 ) 1/2 or more and 8.6 (J/cm 3 ) 1/2 or less include hydrocarbon solvents and ether solvents, and specific examples thereof include normal hexane (SP value: 7.28 (J/cm 3 ) 1/2 ), cyclohexane (SP value: 8.06 (J/cm 3 ) 1/2 ), methylcyclohexane (SP value: 7.92 (J/cm 3 ) 1/2 ), decahydronaphthalene (SP value: 8.53 (J/cm 3 ) 1/2 ), diethyl ether (SP value: 7.25 (J/cm 3 ) 1/2 ), etc.
  • hydrocarbon solvents and ether solvents and specific examples thereof include normal hexane (SP value: 7.28 (J/cm 3 ) 1/2 ), cyclohexane (SP value: 8.06 (J/cm 3 ) 1/2 ), methylcyclohexane (SP value: 7.92 (J/cm
  • the hydrocarbon solvent does not contain an aromatic hydrocarbon solvent, or the hydrocarbon solvent contains an aromatic hydrocarbon solvent, and the content of the aromatic hydrocarbon solvent in the solvent is 1000 ppm or less.
  • the content of the aromatic hydrocarbon solvent 1000 ppm or less the content of volatile organic compounds (VOCs) in the solvent can be reduced, and the effect on the human body can be reduced.
  • a more preferable upper limit of the content of the aromatic hydrocarbon solvent is 700 ppm, and an even more preferable upper limit is 200 ppm, and it is most preferable that the hydrocarbon solvent does not contain the aromatic hydrocarbon solvent.
  • the solvent may further comprise at least one solvent selected from the group consisting of ester solvents and solvents having an SP value of more than 8.6 (J/ cm3 ) 1/2 and not more than 9.0 (J/ cm3 ) 1/2 .
  • the solvent comprises an ester solvent and a solvent having an SP value of more than 8.6 (J/ cm3 ) 1/2 and not more than 9.0 (J/ cm3 ) 1/2 .
  • the ester solvent when the solvent contains an ester solvent, the ester solvent preferably contains an ester compound represented by the above formula (1).
  • the coatability of the acrylic pressure-sensitive adhesive composition of the present invention is further improved.
  • the aliphatic hydrocarbon groups represented by R 1 and R 2 may be saturated or unsaturated.
  • the aliphatic hydrocarbon groups represented by R 1 and R 2 may be linear, branched, or cyclic. When cyclic, the aliphatic hydrocarbon groups may be unsubstituted or may have specific hydrogen atoms substituted with alkyl groups.
  • the content of the hydrocarbon solvent in the total content of the hydrocarbon solvent and the ester solvent is preferably 5.0% by mass or more and less than 100% by mass.
  • the acrylic pressure-sensitive adhesive composition of the present invention can exhibit higher adhesive strength.
  • the coatability of the acrylic pressure-sensitive adhesive composition of the present invention is further improved.
  • the more preferred lower limit of the content of the hydrocarbon solvent is 10% by mass, the more preferred upper limit is 90% by mass, the even more preferred lower limit is 20% by mass, and the even more preferred upper limit is 80% by mass.
  • the SP value of the solvent when the solvent contains a solvent having an SP value of more than 8.6 (J/cm 3 ) 1/2 and not more than 9.0 (J/cm 3 ) 1/2 , the SP value of the solvent preferably has a lower limit of 8.7 (J/cm 3 ) 1/2 and an upper limit of 8.8 (J/cm 3 ) 1/2 .
  • the SP value of the solvent is within the above range, the coatability of the acrylic pressure-sensitive adhesive composition of the present invention is further improved.
  • solvents having an SP value of more than 8.6 (J/cm 3 ) 1/2 and not more than 9.0 (J/cm 3 ) 1/2 include ester-based solvents and ketone-based solvents, and specific examples thereof include ethyl acetate (SP value: 8.74 (J/cm 3 ) 1/2 ), methyl acetate (SP value: 8.77 (J/cm 3 ) 1/2 ), methyl ethyl ketone (SP value: 8.98 (J/cm 3 ) 1/2 ), etc.
  • the acrylic pressure-sensitive adhesive composition of the present invention may further contain a tackifier resin.
  • a tackifier resin By containing a tackifier resin, the acrylic pressure-sensitive adhesive composition of the present invention can exhibit superior adhesive strength.
  • the tackifier resin preferably contains a high hydroxyl value tackifier resin having a hydroxyl value of 15 mgKOH/g or more.
  • the high hydroxyl value tackifier resin has high polarity and is therefore difficult to dissolve in the structural unit derived from the olefin polymer having a polymerizable unsaturated double bond at the terminal having low polarity.
  • rosin resin examples include Pencel D-135, Superester A-125, Pine Crystal KE359 (all manufactured by Arakawa Chemical Industries, Ltd.), Pentalyn C (manufactured by Eastman Chemical Co.), and SYLVALITE 2115 (manufactured by Kraton Corporation).
  • terpene phenol resin examples include YS Polystar G150, YS Polystar T160, YS Polystar T145, YS Polystar TH130, YS Polystar UH115, YS Polystar K125, YS Polystar U130 (all manufactured by Yasuhara Chemical Co., Ltd.), SYLVARES 1150, SYLVARES TP7042 (all manufactured by Kraton Corporation), and the like.
  • the tackifier resin may include a low hydroxyl value tackifier resin having a hydroxyl value of less than 15 mgKOH/g.
  • Examples of the low hydroxyl value tackifier resin include terpene resins, aromatic modified terpene resins, petroleum resins, and styrene resins. These low hydroxyl value tackifier resins may be used alone or in combination of two or more kinds.
  • Examples of the petroleum resin include Arcon P125, Arcon P140 (both manufactured by Arakawa Chemical Industries, Ltd.), Quintone RX110 (manufactured by Zeon Corporation), Petokol 130 (manufactured by Tosoh Corporation), and Petrotac 100V (manufactured by Tosoh Corporation).
  • An example of the styrene resin is YS Resin SX100 (manufactured by Yasuhara Chemical Co., Ltd.).
  • the hydroxyl value of the low hydroxyl value tackifier resin may be less than 15 mgKOH/g, but from the viewpoint of the adhesion of the acrylic pressure-sensitive adhesive composition of the present invention to a low-polarity adherend, the upper limit is preferably 10 mgKOH/g, more preferably 5 mgKOH/g, and most preferably 0 mgKOH/g.
  • the content of the tackifier resin relative to 100 parts by mass of the acrylic copolymer is preferably 40.0 parts by mass or less.
  • the acrylic pressure-sensitive adhesive composition of the present invention is more likely to maintain its adhesiveness.
  • the more preferred upper limit of the content of the tackifier resin is 30.0 parts by mass.
  • the lower limit of the content of the tackifier resin is preferably 5.0 parts by mass.
  • the acrylic pressure-sensitive adhesive composition of the present invention can exhibit higher adhesive strength.
  • the lower limit of the content of the tackifier resin is more preferably 10.0 parts by mass.
  • the acrylic pressure-sensitive adhesive composition of the present invention preferably further contains a crosslinking agent.
  • the acrylic pressure-sensitive adhesive composition of the present invention contains a crosslinking agent, the acrylic copolymer is crosslinked via the crosslinking agent to form a crosslinked structure, which increases the gel fraction of the pressure-sensitive adhesive layer described below. This makes it easier to adjust the gel fraction to the above-mentioned range, and further improves the retention performance at high temperatures.
  • the crosslinking agent may be blended into the acrylic pressure-sensitive adhesive composition of the present invention immediately before forming the pressure-sensitive adhesive layer.
  • the preferred lower limit of the content of the crosslinking agent relative to 100 parts by mass of the acrylic copolymer is 0.01 parts by mass, and the preferred upper limit is 10 parts by mass.
  • the acrylic adhesive composition of the present invention may contain conventionally known fine particles and additives, such as inorganic fine particles, conductive fine particles, antioxidants, foaming agents, organic fillers, and inorganic fillers, as necessary.
  • the method for producing the acrylic pressure-sensitive adhesive composition of the present invention is not particularly limited, and a conventionally known method can be used. For example, first, the (meth)acrylic acid alkyl ester, the olefin polymer having a polymerizable unsaturated double bond at the terminal, the polar functional group-containing monomer, and other monomers as necessary are copolymerized in a conventional manner to obtain the acrylic copolymer. Next, the acrylic pressure-sensitive adhesive composition can be obtained by adding the obtained acrylic copolymer and a solvent, and, as necessary, a tackifier resin, a crosslinking agent, and other additives.
  • the solid content of the acrylic pressure-sensitive adhesive composition of the present invention has a lower limit of 15% by mass and an upper limit of 50% by mass.
  • the acrylic pressure-sensitive adhesive composition of the present invention has excellent coatability.
  • the acrylic pressure-sensitive adhesive composition of the present invention can exhibit high adhesive strength.
  • the solid content of the acrylic pressure-sensitive adhesive composition of the present invention has a preferred lower limit of 20% by mass, a preferred upper limit of 45% by mass, a more preferred lower limit of 25% by mass, and a more preferred upper limit of 40% by mass.
  • the "solid content of the acrylic pressure-sensitive adhesive composition” means the components excluding the solvent in the acrylic pressure-sensitive adhesive composition.
  • the acrylic pressure-sensitive adhesive composition of the present invention is used for a pressure-sensitive adhesive layer or pressure-sensitive adhesive that constitutes a pressure-sensitive adhesive tape.
  • the present invention also includes a pressure-sensitive adhesive formed from the acrylic pressure-sensitive adhesive composition of the present invention, and a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition of the present invention.
  • the adhesive of the present invention may be, for example, a liquid adhesive or a paste adhesive.
  • the adhesive of the present invention is preferably a liquid adhesive because it has excellent application properties.
  • the adhesive of the present invention can be produced, for example, by heating and drying the solution of the acrylic adhesive composition obtained by the above-mentioned method.
  • the adhesive of the present invention can also be produced by thoroughly mixing the solution of the acrylic adhesive composition obtained by the above-mentioned method, and then irradiating it with ultraviolet light or an electron beam.
  • the present invention also provides a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer formed using an acrylic pressure-sensitive adhesive composition, the acrylic pressure-sensitive adhesive composition containing an acrylic copolymer, the acrylic copolymer having a constituent unit derived from an alkyl (meth)acrylate ester and a constituent unit derived from an olefin polymer having a terminal polymerizable unsaturated double bond, the pressure-sensitive adhesive layer containing a solvent, and the solvent including an aliphatic hydrocarbon solvent.
  • the pressure-sensitive adhesive tape of the present invention 20 has no lines or streaks and has a good appearance.
  • the acrylic adhesive composition in the adhesive tape of the present invention 20 is not particularly limited as long as it contains an acrylic copolymer having a structural unit derived from an alkyl (meth)acrylate ester and a structural unit derived from an olefin polymer having a polymerizable unsaturated double bond at the end, but examples thereof include the acrylic adhesive composition of the present invention described above.
  • the acrylic copolymer in the pressure-sensitive adhesive tape of invention 20 examples include the acrylic copolymer in the acrylic pressure-sensitive adhesive composition of the invention described above.
  • the acrylic copolymer in the pressure-sensitive adhesive tape of invention 20 has a constituent unit derived from a polar functional group-containing monomer.
  • the constituent units derived from the polar functional group-containing monomer in the pressure-sensitive adhesive tape of the present invention 20 include constituent units derived from the polar functional group-containing monomer in the acrylic copolymer in the acrylic pressure-sensitive adhesive composition of the present invention described above.
  • the adhesive layer in the adhesive tape of the 20th aspect of the present invention contains a solvent.
  • the solvent in the pressure-sensitive adhesive tape of invention 20 contains an aliphatic hydrocarbon solvent.
  • the pressure-sensitive adhesive layer is free of lines and streaks, resulting in a good appearance.
  • the content of the solvent in the pressure-sensitive adhesive layer is not particularly limited as long as the pressure-sensitive adhesive layer is formed, and may be a trace amount.
  • the specific range of the content of the solvent in the pressure-sensitive adhesive layer is preferably 1.0 ppm or more and 1000 ppm or less.
  • Examples of the aliphatic hydrocarbon solvent in the pressure-sensitive adhesive tape of the 20th invention include the aliphatic hydrocarbon solvents in the acrylic pressure-sensitive adhesive composition of the invention described above.
  • the gel fraction of the pressure-sensitive adhesive layer is preferably 10% by mass at the lower limit and 70% by mass at the upper limit.
  • the pressure-sensitive adhesive layer has excellent cohesive strength, and the pressure-sensitive adhesive tape of the present invention has improved retention performance at high temperatures.
  • the gel fraction of the pressure-sensitive adhesive layer is 70% by mass or less, the pressure-sensitive adhesive layer does not become too hard, and the pressure-sensitive adhesive tape 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, the more preferred upper limit is 60% by mass, the even more preferred lower limit is 25% by mass, and the even more preferred upper limit is 50% by mass.
  • the gel fraction is measured by the following method.
  • Methods for adjusting the gel fraction of the pressure-sensitive adhesive layer to the above-mentioned range include, for example, a method for changing the type or content of a crosslinking agent contained in the acrylic pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer, and a method for adjusting the illuminance or irradiation time of the electron beam or ultraviolet light used when irradiating with an electron beam or ultraviolet light to form the pressure-sensitive adhesive layer, but are not limited to these methods.
  • the content of the aliphatic hydrocarbon solvent in the adhesive layer is preferably 1.0 ppm at the lower limit and 1000 ppm at the upper limit. If the content of the aliphatic hydrocarbon solvent is 1.0 ppm or more, the flexibility of the adhesive tape of the present invention is further improved. If the content of the aliphatic hydrocarbon solvent is 1000 ppm or less, the adhesive strength and retention performance of the adhesive tape of the present invention are further improved. A more preferred lower limit of the content of the aliphatic hydrocarbon solvent is 10 ppm, a more preferred upper limit is 800 ppm, an even more preferred lower limit is 50 ppm, and an even more preferred upper limit is 500 ppm.
  • the adhesive layer does not contain an aromatic hydrocarbon solvent, or the adhesive layer contains an aromatic hydrocarbon solvent, and the content of the aromatic hydrocarbon solvent in the adhesive layer is preferably 300 ppm or less. If the content of the aromatic hydrocarbon solvent is 300 ppm or less, the content of volatile organic compounds (VOCs) in the adhesive layer is low, and the effect of the adhesive tape of the present invention on the human body can be further suppressed.
  • a more preferred upper limit of the content of the aromatic hydrocarbon solvent in the adhesive layer is 200 ppm, and an even more preferred upper limit is 100 ppm, and it is most preferred that the adhesive layer does not contain an aromatic hydrocarbon solvent.
  • the content of the aliphatic hydrocarbon solvent or aromatic hydrocarbon solvent in the pressure-sensitive adhesive layer can be measured by gas chromatography mass spectrometry (GC/MS), and can be calculated from the spectrum obtained by measuring a measurement sample obtained by diluting the sol component of the pressure-sensitive adhesive layer using a gas chromatograph mass spectrometer.
  • GC/MS gas chromatography mass spectrometry
  • a pure substance of the identified aliphatic hydrocarbon solvent or aromatic hydrocarbon solvent is used as a known standard substance, and a measurement sample obtained by diluting the sol component of the pressure-sensitive adhesive layer with chloroform is subjected to gas chromatography mass spectrometry (GC-MS), a calibration curve is created from the measured peak areas, and the content of the aliphatic hydrocarbon solvent or aromatic hydrocarbon solvent is calculated using the created calibration curve, thereby making it possible to measure the content.
  • the "sol component” refers to the component remaining after removing the gel component from the pressure-sensitive adhesive layer.
  • the sol component of the pressure-sensitive adhesive layer can be obtained, for example, by immersing the pressure-sensitive adhesive layer in tetrahydrofuran (THF) at 23°C for 24 hours, filtering the insoluble matter through a 200-mesh wire screen, and removing the gel component.
  • THF tetrahydrofuran
  • the gas chromatography mass spectrometry is performed under the following measurement conditions, for example.
  • the thickness of the pressure-sensitive adhesive layer is preferably 5 ⁇ m at the lower limit and 500 ⁇ m at the upper limit.
  • the thickness of the pressure-sensitive adhesive layer is 5 ⁇ m or more, the pressure-sensitive adhesive tape of the present invention is likely to have good adhesion to the adherend.
  • the thickness of the pressure-sensitive adhesive layer is 500 ⁇ m or less, high productivity is likely to be obtained during the production of the pressure-sensitive adhesive tape.
  • the more preferred lower limit of the thickness of the pressure-sensitive adhesive layer is 10 ⁇ m, the more preferred upper limit is 300 ⁇ m, the even more preferred lower limit is 20 ⁇ m, and the even more preferred upper limit is 200 ⁇ m.
  • the thickness can be measured using a dial thickness meter (such as "ABS Digimatic Indicator" manufactured by Mitutoyo Corporation).
  • the adhesive tape of the present invention may be a non-support type that does not have a substrate, or a support type that has a substrate.
  • the adhesive tape of the present invention it is preferable that the adhesive tape of the present invention has a substrate.
  • the adhesive tape of the present invention may be a single-sided adhesive tape having an adhesive layer on one side of the substrate, or a double-sided adhesive tape having adhesive layers on both sides of the substrate.
  • the preferred lower limit of the thickness of the substrate is 1.0 ⁇ m, and the preferred upper limit is 1000 ⁇ m.
  • the adhesive tape has good processability.
  • the thickness of the substrate is 1000 ⁇ m or less, the flexibility of the adhesive tape is improved.
  • a more preferred lower limit of the thickness of the substrate is 5.0 ⁇ m, a more preferred upper limit is 500 ⁇ m, an even more preferred lower limit is 10 ⁇ m, and an even more preferred upper limit is 300 ⁇ m.
  • the adhesive tape of the present invention may further have other layers as long as the effects of the present invention are not impaired.
  • the pressure-sensitive adhesive tape of the present invention can be produced, for example, by applying a solution of the acrylic pressure-sensitive adhesive composition obtained by the above-mentioned method onto a release-treated surface of a release film that has been subjected to a release treatment, followed by drying to form a pressure-sensitive adhesive layer, etc.
  • the pressure-sensitive adhesive tape produced by the above-mentioned method can also be laminated as a pressure-sensitive adhesive layer to a substrate to produce a pressure-sensitive adhesive tape having a substrate.
  • the pressure-sensitive adhesive tape of the present invention can also be produced by thoroughly mixing the solution of the acrylic pressure-sensitive adhesive composition obtained by the method described above, applying the mixture to a release-treated surface of a release film that has been subjected to a release treatment, and then heating or irradiating with ultraviolet rays or an electron beam, etc., followed by drying to form a pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition.
  • the present invention also provides a method for producing a pressure-sensitive adhesive tape, which comprises a step of applying the acrylic pressure-sensitive adhesive composition.
  • the preferred lower limit of the overall thickness of the adhesive tape of the present invention is 10 ⁇ m, and the preferred upper limit is 2000 ⁇ m.
  • the overall thickness of the adhesive tape of the present invention is 10 ⁇ m or more, the application of the adhesive tape of the present invention becomes easier.
  • a more preferred lower limit of the overall thickness of the adhesive tape of the present invention is 20 ⁇ m, a more preferred upper limit is 1000 ⁇ m, an even more preferred lower limit is 30 ⁇ m, and an even more preferred upper limit is 800 ⁇ m.
  • the applications of the adhesive of the present invention and the adhesive tape of the present invention are not particularly limited, but can be used, for example, to fasten parts in electronic devices, vehicles, housing, building materials, etc.
  • the present invention also includes a method for producing an acrylic copolymer, which comprises a step of polymerizing a monomer mixture containing an alkyl (meth)acrylate ester and an olefin polymer having a terminal polymerizable unsaturated double bond in a solvent in the presence of a polymerization initiator (hereinafter, sometimes simply referred to as "step (i)"), wherein the solvent contains a hydrocarbon solvent.
  • step (i) a polymerization initiator
  • the solution containing the acrylic copolymer obtained by the method for producing an acrylic copolymer of the present invention has excellent coatability and adhesive strength, and can be used as it is as an acrylic pressure-sensitive adhesive composition.
  • the (meth)acrylic acid alkyl ester and the olefin polymer having a terminal polymerizable unsaturated double bond can be the same as those that can be used in the acrylic pressure-sensitive adhesive composition of the present invention described above.
  • the solvent contains a hydrocarbon solvent.
  • a hydrocarbon solvent By containing a hydrocarbon solvent, the olefin polymer having a polymerizable unsaturated double bond at the terminal can be uniformly introduced into the acrylic copolymer.
  • the above-mentioned hydrocarbon solvent preferably contains an aliphatic hydrocarbon solvent.
  • an aliphatic hydrocarbon solvent By containing an aliphatic hydrocarbon solvent in the above-mentioned hydrocarbon solvent, the amount of volatile organic compounds (VOCs) used in the production of the acrylic copolymer can be reduced, and the impact on the human body can be reduced.
  • the aliphatic hydrocarbon solvent preferably contains an aliphatic hydrocarbon compound having 6 to 9 carbon atoms.
  • an aliphatic hydrocarbon compound having 6 to 9 carbon atoms in the aliphatic hydrocarbon solvent, the olefin polymer having a polymerizable unsaturated double bond at the terminal can be introduced more uniformly into the acrylic copolymer.
  • examples of the aliphatic hydrocarbon compound having 6 to 9 carbon atoms include normal hexane, cyclohexane, methylcyclohexane, normal heptane, cycloheptane, methylcycloheptane, normal octane, cyclooctane, methylcyclooctane, normal nonane, and cyclononane.
  • the content of the aromatic hydrocarbon solvent in the solvent is preferably 300 ppm at the upper limit.
  • the amount of volatile organic compounds (VOCs) used in the production of the acrylic copolymer can be reduced, and the impact on the human body can be reduced.
  • a more preferred upper limit of the content of the aromatic hydrocarbon solvent is 200 ppm, and an even more preferred upper limit is 100 ppm, and it is most preferred that the solvent does not contain the aromatic hydrocarbon solvent.
  • the solvent may contain an ester-based solvent.
  • the solvent contains an ester-based solvent, the coatability of the solution containing the acrylic copolymer obtained by the method for producing an acrylic copolymer of the present invention is further improved, and the solution can be more suitably used as an acrylic pressure-sensitive adhesive composition.
  • the ester solvent preferably contains an ester compound represented by the above formula (1).
  • the ester solvent contains an ester compound represented by the above formula (1), the coatability of the solution containing the acrylic copolymer obtained by the method for producing an acrylic copolymer of the present invention is further improved, and the solution can be more suitably used as an acrylic pressure-sensitive adhesive composition.
  • the content of the hydrocarbon solvent in the total content of the hydrocarbon solvent and the ester solvent is preferably 5.0% by mass or more and less than 100% by mass.
  • the coatability of the solution containing the acrylic copolymer obtained by the method for producing an acrylic copolymer of the present invention is further improved, and the solution can be more suitably used as an acrylic pressure-sensitive adhesive composition.
  • a more preferred lower limit of the content of the hydrocarbon solvent is 10% by mass, a more preferred upper limit is 90% by mass, an even more preferred lower limit is 20% by mass, and an even more preferred upper limit is 80% by mass.
  • examples of the polymerization initiator 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.
  • examples of the azo compound include azobisisobutyronitrile and azobiscyclohexanecarbonitrile.
  • the preferred lower limit of the amount of the polymerization initiator relative to 100 parts by mass of the monomer mixture is 0.01 parts by mass, and the preferred upper limit is 3.0 parts by mass.
  • a more preferred lower limit of the amount of the polymerization initiator is 0.03 parts by mass, a more preferred upper limit is 2.0 parts by mass, an even more preferred lower limit is 0.05 parts by mass, and an even more preferred upper limit is 1.0 parts by mass.
  • the temperature at which the monomer mixture is polymerized in a solvent in the presence of a polymerization initiator has a preferred lower limit of 50°C and a preferred upper limit of 100°C.
  • a polymerization reaction temperature has a preferred lower limit of 50°C and a preferred upper limit of 100°C.
  • a more preferred lower limit of the polymerization reaction temperature is 55°C, a more preferred upper limit is 95°C, an even more preferred lower limit is 60°C, and an even more preferred upper limit is 90°C.
  • an acrylic adhesive composition that has excellent coatability, can be applied without lines or streaks, and can exert high adhesive strength.
  • FIG. 2 is a diagram showing a schematic diagram of a method for evaluating retention performance at high temperatures.
  • the weight average molecular weight (Mw) of the obtained acrylic copolymer A was measured using gel permeation chromatography (GPC) (manufactured by Waters, "2690 Separations Module”) under the following conditions, and the polydispersity of the acrylic copolymer A was calculated.
  • GPC gel permeation chromatography
  • Solvent Tetrahydrofuran Sample flow rate: 1 mL/min Detector: Differential refractometer RI Column: GPC KF-806L (Showa Denko) Column temperature (measurement temperature): 40°C Injection volume: 20 ⁇ L
  • the weight-average molecular weights of the acrylic copolymers O to P were adjusted by adjusting the concentration of the monomer mixture in the polymerization reaction.
  • the concentration of the monomer mixture was 30% by mass
  • the concentration of the monomer mixture was 40% by mass, thereby adjusting the weight-average molecular weights of the acrylic copolymers.
  • Example 1 (Preparation of Acrylic Pressure-Sensitive Adhesive Composition) Relative to 100 parts by mass of the solid content of the solution containing acrylic copolymer A, 20.0 parts by mass of YS Polystar G150 (manufactured by Yasuhara Chemical Co., Ltd.) as a tackifier resin and 1.0 part by mass of Desmodur L-75 (manufactured by Covestro) as a crosslinking agent were added, and the solution containing acrylic copolymer A was diluted so that the amount of cyclohexane and the amount of ethyl acetate were 150 parts by mass and 150 parts by mass, respectively, relative to 100 parts by mass of acrylic copolymer A, thereby obtaining an acrylic pressure-sensitive adhesive composition.
  • YS Polystar G150 manufactured by Yasuhara Chemical Co., Ltd.
  • Desmodur L-75 manufactured by Covestro
  • the adhesive layer of the obtained adhesive tape was collected in an amount of W 0 (g), immersed in 50 mL of tetrahydrofuran (THF), and shaken in a shaker at 23° C. and 200 rpm for 24 hours. After shaking, the THF and the adhesive absorbing and swollen with THF were filtered out using a metal mesh (opening #200 mesh, mass: W 1 (g)), and the adhesive absorbing and swollen with THF was dried for 1 hour under conditions of 110° C., after which the mass W 2 (g) of the adhesive including the metal mesh was measured, and the gel fraction was calculated using the following formula (I).
  • Example 42 to 44 An acrylic pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that the composition was as shown in Table 7, by the same method as in "(Preparation of acrylic pressure-sensitive adhesive composition)" described above. After thoroughly stirring the obtained solution of the acrylic pressure-sensitive adhesive composition, the solution was coated with a doctor knife on a release-treated surface of a 50 ⁇ m-thick release polyethylene terephthalate (PET) film with one side subjected to release treatment, and the coating solution was dried by heating at 110° C. for 10 minutes to form a 50 ⁇ m-thick pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition. Then, the pressure-sensitive adhesive layer formed on one side of the substrate shown in Table 7 was bonded.
  • PET polyethylene terephthalate
  • the pressure-sensitive adhesive layer formed in the above-mentioned "(Preparation of Pressure-sensitive Adhesive Tape)" was visually observed, and the coatability and appearance were evaluated according to the following criteria.
  • the release PET film on one side of the obtained adhesive tape was peeled off, and the exposed adhesive layer was attached to a polyethylene terephthalate (PET) film having a thickness of 23 ⁇ m so that air would not enter, and then the film was cut to a width of 25 mm x length of 100 mm to prepare a test piece.
  • PET polyethylene terephthalate
  • the obtained test piece was attached to a SUS plate (SUS304 plate washed with ethanol and then wiped dry) by moving a 2 kg rubber roller back and forth at a speed of 300 mm/min to prepare a measurement sample.
  • the obtained measurement sample was subjected to a 180° peel test in accordance with JIS Z0237 using a tensile tester (manufactured by A&D Co., Ltd., "RTI-1310") under conditions of 23°C, 50% RH, and a peel speed of 300 mm/min, and the 180° peel force (N/25 mm) was measured by peeling the adhesive tape from the SUS plate.
  • the adhesive strength was evaluated using the obtained 180° peel strength according to the following criteria. ⁇ : The 180° peel strength was 35 N/25 mm or more.
  • the 180° peel force was 30 N/25 mm or more and less than 35 N/25 mm.
  • the 180° peel force was 25 N/25 mm or more and less than 30 N/25 mm.
  • the 180° peel strength was less than 25 N/25 mm.
  • the release PET film on one side of the obtained adhesive tape was peeled off, and the tape was attached to a polyethylene terephthalate (PET) film having a thickness of 23 ⁇ m without allowing air to enter, and then cut into strips having a width of 25 mm.
  • PET polyethylene terephthalate
  • the tape was then attached to a SUS plate (a SUS304 plate washed with ethanol and then wiped dry) by moving a 2 kg rubber roller back and forth at a speed of 300 mm/min.
  • the adhesive tape was cut so that the adhesive area was 25 mm x 25 mm, and the tape was left to stand at 23 ° C for 20 minutes to prepare a test sample.
  • the prepared test sample was placed in an oven at 80 ° C and heated for another 20 minutes, and then a 500 g weight was hung as shown in FIG. 1 under the conditions of 80 ° C and 50% RH, and a load was applied in the shear direction.
  • the amount of displacement (movement) (mm) from the cut position 1 hour after the load was applied was measured with a scale magnifying glass.
  • the retention performance at high temperatures was evaluated according to the following criteria.
  • ⁇ The amount of deviation was 0.5 mm or more and less than 25 mm.
  • x The amount of deviation was 25 mm or more, and the adhesive tape fell off. Even if the evaluation is "x", the pressure-sensitive adhesive tape of the present invention can be used without any problem depending on the application.
  • the odor level was evaluated in accordance with VDA270. Specifically, an adhesive tape cut to a size of 5 cm wide x 10 cm long (size: 50 cm2 ) was placed in a glass bottle with a capacity of 1.0 L, and the glass bottle containing the adhesive tape was left to stand in an environment of 40°C for 24 hours.The adhesive tape was then removed from the glass bottle, and the level of odor immediately after removal was judged using the following 6-point method. 1: No odor was perceptible. 2: A slight odor was noticeable, but not unpleasant. 3: The odor was clearly noticeable, but not unpleasant. 4: The odor was clearly noticeable and unpleasant. 5: The odor was clearly noticeable and very unpleasant. 6: The odor was clearly noticeable and unbearably unpleasant.
  • the calculated average was evaluated as follows: if it was less than 3.0, it was marked “good”, if it was less than 4.0 and 3.0 or more, it was marked “good”, and if it was 4.0 or more, it was marked “bad”. Even if the evaluation is "x", the pressure-sensitive adhesive tape of the present invention can be used without any problem depending on the application.
  • an acrylic adhesive composition that has excellent coatability, can be applied without lines or streaks, and can exert high adhesive strength.

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