CN110093122B - Adhesive composition, adhesive sheet, and method for producing adhesive - Google Patents

Adhesive composition, adhesive sheet, and method for producing adhesive Download PDF

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Publication number
CN110093122B
CN110093122B CN201811319076.5A CN201811319076A CN110093122B CN 110093122 B CN110093122 B CN 110093122B CN 201811319076 A CN201811319076 A CN 201811319076A CN 110093122 B CN110093122 B CN 110093122B
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group
adhesive
acrylic polymer
adhesive composition
active hydrogen
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CN110093122A (en
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后藤航也
武藤圭介
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Saiden Chemical Industry Co Ltd
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Saiden Chemical Industry Co Ltd
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    • 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
    • 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
    • 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
    • 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
    • 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
    • C09J7/25—Plastics; Metallised plastics based on macromolecular compounds obtained otherwise than by reactions involving only carbon-to-carbon unsaturated bonds
    • C09J7/255—Polyesters
    • 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
    • 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
    • C08F220/14—Methyl esters, e.g. methyl (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
    • C08F220/12—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
    • 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
    • C08F220/1804—C4-(meth)acrylate, e.g. butyl (meth)acrylate, isobutyl (meth)acrylate or tert-butyl (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
    • 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
    • C09J2301/302—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 the adhesive being pressure-sensitive, i.e. tacky at temperatures inferior to 30°C
    • 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
    • C09J2433/00—Presence of (meth)acrylic polymer
    • 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
    • C09J2467/00—Presence of polyester
    • C09J2467/006—Presence of polyester in the substrate

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Adhesive Tapes (AREA)
  • Adhesives Or Adhesive Processes (AREA)
  • Dicing (AREA)

Abstract

The invention relates to an adhesive composition, an adhesive sheet and a method for producing the adhesive. Provided is an adhesive composition for forming an adhesive having reduced adhesive force by irradiation with active energy rays, comprising: an acrylic polymer (a) having an active hydrogen group; a compound (B) having a functional group that reacts with the active hydrogen group and a carbon-carbon double bond, wherein the acrylic polymer (A) that contributes to the formation of the pressure-sensitive adhesive is provided with the carbon-carbon double bond, and the rate of change in mass when heated at 90 ℃ for 5 minutes is 5% or less; and a crosslinking agent (C) having 2 or more functional groups reactive with the active hydrogen groups. The equivalent weight of the carbon-carbon double bond of the compound (B) is 1.9meq/g or more relative to the acrylic polymer (A), or the content of the compound (B) is 30-150 parts by mass relative to 100 parts by mass of the acrylic polymer (A).

Description

Adhesive composition, adhesive sheet, and method for producing adhesive
Technical Field
The invention relates to an adhesive composition, an adhesive sheet and a method for producing the adhesive.
Background
Adhesive sheets are used for various purposes such as fixing, bonding, protecting, decorating, and transporting articles. A typical example of the pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet including a pressure-sensitive adhesive (pressure-sensitive adhesive layer) formed from a pressure-sensitive adhesive composition containing an acrylic polymer as a base polymer. Among pressure-sensitive adhesive sheets having a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing an acrylic polymer, there is also known a pressure-sensitive adhesive sheet in which the adhesive strength of the pressure-sensitive adhesive layer is reduced by irradiation with active energy rays such as ultraviolet rays and electron beams.
Pressure-sensitive adhesive sheets in which the adhesive strength of the pressure-sensitive adhesive layer is reduced by irradiation with active energy rays are used, for example, as dicing tapes and UV tapes in the field of IC chip production. In the case of manufacturing IC chips, when a semiconductor wafer which is adhered and fixed in advance to an adhesive sheet is diced along the chip shape, the adhesive layer is required to have sufficient adhesive force for fixing the semiconductor wafer and the divided chips. Meanwhile, when the divided chips are peeled from the adhesive sheet and mounted on a substrate or the like, the adhesive layer is required to have a property that the adhesive force is reduced by irradiation with active energy rays, and the chips can be easily peeled.
For example, patent document 1 discloses a photosensitive adhesive tape obtained by applying a photosensitive adhesive composition containing an acrylic high molecular weight material having a photoactive functional group in an amount of 0.01 to 1.0meq/g, a thermal crosslinking agent, and a photopolymerization initiator on one surface of a substrate having transparency to ultraviolet rays. In addition, for example, patent document 2 discloses the following: in the adhesive sheet for processing semiconductor wafers, which is provided with an adhesive layer having a reduced adhesive strength by curing with radiation, the adhesive composition for forming the adhesive layer contains, as a main component, a polymer having a carbon-carbon double bond in a side chain.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open No. 2001-139905
Patent document 2: japanese patent laid-open publication No. 2001-200215
Disclosure of Invention
Problems to be solved by the invention
In the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer of the photosensitive pressure-sensitive adhesive tape disclosed in patent document 1, a polymer in which a photoactive functional group (a group having a carbon-carbon double bond) is previously introduced into an acrylic high-molecular weight material is used. In addition, in the adhesive composition for forming the adhesive layer of the adhesive sheet disclosed in patent document 2, a polymer in which a carbon-carbon double bond is introduced into the intramolecular chain by an addition reaction of 2-methacryloyloxyethyl isocyanate and an acrylic copolymer in advance is used.
As described above, conventionally, in order to reduce the adhesive force of an adhesive by irradiation with active energy rays, the following operations have been performed in advance for an acrylic polymer used in an adhesive composition for forming an adhesive: carbon-carbon double bonds that undergo a curing reaction upon irradiation with active energy rays are introduced in advance. In the above case, in order to sufficiently reduce the adhesive strength of the pressure-sensitive adhesive after irradiation with active energy rays, if a large amount of carbon-carbon double bonds are introduced into the acrylic polymer in advance, gelation occurs and coating becomes difficult, and therefore, it becomes difficult to use the pressure-sensitive adhesive composition. Therefore, it is considered that the amount of carbon-carbon double bonds introduced in advance in the acrylic polymer must be set to such an amount that gelation does not occur.
On the other hand, there are practical cases: depending on the use of the pressure-sensitive adhesive in which the adhesive strength is reduced by irradiation with active energy rays, a pressure-sensitive adhesive in which the adhesive strength is further reduced after irradiation with active energy rays and which can be easily peeled off is desired.
In view of the above circumstances, the present invention is intended to provide: an adhesive composition capable of forming an adhesive having more effectively reduced adhesive force by irradiation with active energy rays.
Means for solving the problems
According to the present invention, there is provided an adhesive composition for forming an adhesive having reduced adhesive force by irradiation with active energy rays, the adhesive composition comprising: an acrylic polymer (a) having an active hydrogen group; a compound (B) having a functional group that reacts with the active hydrogen group and a carbon-carbon double bond, wherein the acrylic polymer (A) that contributes to the formation of the pressure-sensitive adhesive is provided with the carbon-carbon double bond, and the rate of change in mass when heated at 90 ℃ for 5 minutes is 5% or less; and a crosslinking agent (C) having 2 or more functional groups reactive with the active hydrogen groups, wherein the equivalent weight of the carbon-carbon double bond of the compound (B) is 1.9meq/g or more based on the acrylic polymer (A).
Further, according to the present invention, there is provided an adhesive composition for forming an adhesive having reduced adhesive force by irradiation with active energy rays, the adhesive composition comprising: an acrylic polymer (a) having an active hydrogen group; a compound (B) having a functional group that reacts with the active hydrogen group and a carbon-carbon double bond, wherein the acrylic polymer (A) that contributes to the formation of the pressure-sensitive adhesive is provided with the carbon-carbon double bond, and the rate of change in mass when heated at 90 ℃ for 5 minutes is 5% or less; and a crosslinking agent (C) having 2 or more functional groups reactive with the active hydrogen group, wherein the content of the compound (B) is 30 to 150 parts by mass per 100 parts by mass of the acrylic polymer (A).
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, there can be provided: an adhesive composition capable of forming an adhesive having more effectively reduced adhesive force by irradiation with active energy rays.
Detailed Description
Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the embodiments below. In the present disclosure, the term "(meth) acrylic acid" includes both terms of "acrylic acid" and "methacrylic acid". In addition, the term "(meth) acrylate" also includes both the terms "acrylate" and "methacrylate".
< adhesive composition >
The adhesive composition according to an embodiment of the present invention is used for forming an adhesive having reduced adhesive force by irradiation with active energy rays. The pressure-sensitive adhesive composition can form a pressure-sensitive adhesive having an appropriate adhesive force to an adherend before irradiation with an active energy ray, and can form a pressure-sensitive adhesive which has a reduced adhesive force and is easily peeled from the adherend after irradiation with an active energy ray. Specific examples of the active energy ray include α -ray, β -ray, γ -ray, electron beam, neutron beam, X-ray, near infrared ray, visible ray, ultraviolet ray, and the like. 1 or 2 or more of them may be used. As the active energy ray, ultraviolet rays are more suitable.
An adhesive composition according to an embodiment of the present invention includes: an acrylic polymer (a) having an active hydrogen group; a compound (B) having a carbon-carbon double bond and a functional group reactive with the active hydrogen group; and a crosslinking agent (C) having 2 or more functional groups reactive with the active hydrogen groups. The compound (B) used in the adhesive composition has a mass change rate of 5% or less when heated at 90 ℃ for 5 minutes. In addition, the compound (B) imparts a carbon-carbon double bond to the acrylic polymer (a) which contributes to the formation of the adhesive. In the adhesive composition, the equivalent weight of the carbon-carbon double bond of the compound (B) is 1.9meq/g or more relative to the acrylic polymer (A), or the content of the compound (B) is 30-150 parts by mass relative to 100 parts by mass of the acrylic polymer (A).
With the above-described configuration, when the pressure-sensitive adhesive composition is applied and dried or cured, the compound (B) can be efficiently reacted with the acrylic polymer (a) which is advantageous for forming the pressure-sensitive adhesive, and carbon-carbon double bonds can be efficiently introduced. Therefore, the binder composition having the above-described structure can form a binder containing a polymer in which the amount of carbon-carbon double bonds is further increased. When the adhesive is peeled off, the adhesive may be irradiated with active energy rays. By irradiating the adhesive with active energy rays, a curing reaction can be caused by the carbon-carbon double bond, and as a result, the adhesive strength of the adhesive can be effectively reduced, and the adhesive can be easily peeled. Hereinafter, each component constituting the adhesive composition will be described.
[ acrylic Polymer (A) ]
The acrylic polymer (a) is a component to be a base polymer of the adhesive composition. The acrylic polymer (a) is used in a manner that the acrylic polymer (a) itself contributes to the formation of the adhesive, unlike the manner in which the acrylic polymer (a) is reacted with the compound (B) described later in advance before the formation of the adhesive, to form the adhesive.
The active hydrogen group in the acrylic polymer (a) is an active hydrogen-containing group. Active hydrogen is a highly reactive hydrogen atom among hydrogen atoms contained in a molecule. Examples of the active hydrogen include hydrogen atoms bonded to atoms other than carbon atoms (for example, oxygen atoms, nitrogen atoms, sulfur atoms, and the like). The acrylic polymer (a) has an active hydrogen group, and is therefore reactive with a compound (B) (a functional group of the compound (B)) or a crosslinking agent (C) (a functional group of the crosslinking agent (C)) described later. Examples of the active hydrogen group of the acrylic polymer (a) include a hydroxyl group, a carboxyl group, an amino group, an amide group, a mercapto group, a sulfonic acid group, and a phosphoric acid group. The acrylic polymer (a) preferably has 1 or 2 or more of these active hydrogen groups.
The acrylic polymer (a) having an active hydrogen group is a polymer ((meth) acrylate-based polymer) containing a structural unit derived from a (meth) acrylate ester, and a (meth) acrylate-based copolymer is preferable. In the present specification, when simply referred to as "polymer", the polymer includes a homopolymer of 1 kind of monomer and a copolymer of 2 or more kinds of monomers. In the present specification, the term "structural unit" refers to a monomer unit constituting a polymer. Examples of the structural unit derived from a monomer include: and a structural unit in which a polymerizable double bond (C ═ C) in the monomer is cleaved to form a single bond (-C — C-).
Examples of the acrylic polymer (a) include: a polymer of a monomer component containing a (meth) acrylate having an active hydrogen group; a copolymer of a monomer having an active hydrogen group and a monomer component containing a (meth) acrylate having no active hydrogen group, and the like. That is, examples of the acrylic polymer (a) include: a polymer containing a structural unit derived from a (meth) acrylate having an active hydrogen group; a copolymer containing a structural unit derived from a monomer having an active hydrogen group and a structural unit derived from a (meth) acrylate ester having no active hydrogen group, and the like.
The acrylic polymer (a) preferably comprises: a structural unit derived from a (meth) acrylate (a1) (hereinafter, sometimes simply referred to as "(meth) acrylate (a 1)") other than the (meth) acrylate having an active hydrogen group, and a structural unit derived from a monomer (a2) having an active hydrogen group. Further, the acrylic polymer (a) may contain a structural unit derived from a monomer other than these monomers. The acrylic polymer (a) is preferably obtained by polymerizing (copolymerizing) a monomer component (monomer mixture) containing a (meth) acrylic acid ester (a1) as a main component (50% by mass or more of the monomer components) of the monomers constituting the acrylic polymer (a) and a monomer (a2) having an active hydrogen group.
((meth) acrylate (a1))
Examples of the (meth) acrylate (a1) other than the (meth) acrylate having an active hydrogen group include CH2＝CR1-COO-R2(R1Represents a hydrogen atom or a methyl group, R2Representing an organic group containing no active hydrogen). R2The number of carbon atoms (C) is preferably 1 to 18, more preferably 1 to 16, and still more preferably 1 to 12. As R2Examples thereof include alkyl groups, cycloalkyl groups, alkoxyalkyl groups, aryl groups, aralkyl groups, and alkoxypolyalkylene glycol groups.
As the (meth) acrylic acid ester (a1), an alkyl (meth) acrylate is preferable. Examples of the alkyl (meth) acrylate include: methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, and octadecyl (meth) acrylate, and the like. Specific examples of the alkyl (meth) acrylate may include 1 kind or 2 or more kinds of the alkyl (meth) acrylate. The number of carbon atoms of the alkyl group in the alkyl (meth) acrylate is preferably 1 to 18, more preferably 1 to 16, and still more preferably 1 to 12.
Examples of the (meth) acrylic acid ester (a1) include, in addition to the alkyl (meth) acrylate: cycloalkyl (meth) acrylates such as cyclopentyl (meth) acrylate and cyclohexyl (meth) acrylate; alkoxyalkyl (meth) acrylates such as 2-methoxyethyl (meth) acrylate and 2-ethoxyethyl (meth) acrylate; aryl (meth) acrylates such as phenyl (meth) acrylate; aralkyl (meth) acrylates such as benzyl (meth) acrylate and 2-phenylethyl (meth) acrylate; and alkoxy polyalkylene glycol mono (meth) acrylates such as methoxy diethylene glycol mono (meth) acrylate, methoxy polyethylene glycol mono (meth) acrylate, methoxy dipropylene glycol mono (meth) acrylate, and ethoxy diethylene glycol mono (meth) acrylate; and the like. Specific examples of the (meth) acrylic acid ester (a1) listed above may be used alone or in combination of 1 or more.
The proportion of the (meth) acrylic acid ester (a1) in the acrylic polymer (a) is preferably 50 to 99% by mass based on the total mass of the monomer components constituting the acrylic polymer (a). The proportion of the (meth) acrylic acid ester (a1) is more preferably 60% by mass or more, still more preferably 70% by mass or more, and still more preferably 95% by mass or less, still more preferably 90% by mass or less, based on the total mass of the monomer components constituting the acrylic polymer (a).
(monomer (a2) having an active hydrogen group)
As the monomer (a2) having an active hydrogen group, a monomer having an active hydrogen group in the molecule and copolymerizable with the (meth) acrylate (a1) can be used. Examples of such a monomer (a2) include monomers having a polymerizable double bond and the active hydrogen group. Examples of such a monomer (a2) include: a monomer having a hydroxyl group as an active hydrogen group; a monomer having a carboxyl group as an active hydrogen group; a monomer having an amino group as an active hydrogen group; a monomer having an amide group as an active hydrogen group; and a monomer having a sulfonic acid group as an active hydrogen group; and the like. One or more of them may be used alone or in combination of 2 or more.
Examples of the monomer having a hydroxyl group include (meth) acrylates having a hydroxyl group. Specific examples thereof include: hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 8-hydroxyoctyl (meth) acrylate; hydroxyl-terminated polyalkylene glycol mono (meth) acrylates such as polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and polyethylene-polypropylene glycol mono (meth) acrylate; and glycerol mono (meth) acrylate. The number of carbon atoms of the hydroxyalkyl group in the hydroxyalkyl (meth) acrylate is preferably 2 to 8, more preferably 2 to 6.
Examples of the monomer having a carboxyl group include: ethylenically unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, fumaric acid, and citraconic acid; and carboxyl group-containing (meth) acrylates such as β -carboxyethyl (meth) acrylate.
Examples of the monomer having an amino group include (meth) acrylate monomers having an amino group (a primary amino group or a secondary amino group). Specific examples thereof include: monoalkylaminoalkyl (meth) acrylates such as monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, and isopropylaminoethyl (meth) acrylate. The number of carbon atoms of the monoalkylaminoalkyl group in the monoalkylaminoalkyl (meth) acrylate is preferably 2 to 10, more preferably 2 to 8, and still more preferably 2 to 6.
Examples of the monomer having an amide group include: (meth) acrylamide; and N-monoalkyl-substituted acrylamides such as N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methylol (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, N-propyl (meth) acrylamide, N- (butoxymethyl) (meth) acrylamide, and N-hexyl (meth) acrylamide. The number of carbon atoms in the alkyl group of the N-monoalkyl-substituted acrylamide is preferably 1 to 8, more preferably 1 to 6.
Examples of the monomer having a sulfonic acid group include: styrene sulfonic acid, allyl sulfonic acid, 2-sulfoethyl (meth) acrylate, 3-sulfopropyl (meth) acrylate, and 2- (meth) acrylamide-2-methylpropane sulfonic acid, and salts thereof and hydrates thereof, and the like.
In the specific example of the monomer having an active hydrogen group (a2), 1 or more may be used alone. As the monomer (a2) having an active hydrogen group, at least one of a monomer having a hydroxyl group and a monomer having a carboxyl group is preferably used. Among these, at least one of hydroxyalkyl (meth) acrylate and ethylenically unsaturated carboxylic acid is more preferably used, and at least one of 2-hydroxyethyl (meth) acrylate and (meth) acrylic acid is further preferably used.
The proportion of the monomer (a2) having an active hydrogen group in the acrylic polymer (a) is preferably 1 to 50% by mass based on the total mass of the monomer components constituting the acrylic polymer (a). The ratio of the monomer having an active hydrogen group (a2) is more preferably 2% by mass or more, still more preferably 5% by mass or more, and still more preferably 40% by mass or less, still more preferably 30% by mass or less, based on the total mass of the monomer components constituting the acrylic polymer (a).
As the other monomer (a3) that can be used for the acrylic polymer (a) in addition to the above (meth) acrylate (a1) and the monomer (a2) having an active hydrogen group, a monomer copolymerizable with the (meth) acrylate (a1) and the monomer (a2) can be mentioned. Examples of such a monomer (a3) include: styrene, α -methylstyrene, vinyltoluene, divinylbenzene, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl decanoate, glycidyl (meth) acrylate, acrylonitrile, methacrylonitrile, and the like. 1 or 2 or more of them may be used.
The acrylic polymer (a) more preferably has either or both of a hydroxyl group and a carboxyl group as an active hydrogen group, and further preferably has at least a hydroxyl group as an active hydrogen group. The equivalent weight of the hydroxyl group of the acrylic polymer (A) having a hydroxyl group is preferably 0.5meq/g or more and 2.0meq/g or less, more preferably 0.6meq/g or more and 1.8meq/g or less, and still more preferably 0.8meq/g or more and 1.5meq/g or less.
In the present specification, the equivalent of the hydroxyl group of the acrylic polymer (a) is the milliequivalent (meq/g) of the hydroxyl group in 1g of the acrylic polymer (a), and is a calculated value calculated from the charged amount of the raw material. Specifically, the equivalent E of hydroxyl group of the acrylic polymer (A)OH(meq/g) may be derived from the acrylic polymer (A) contained in the adhesive compositionMass WA(g) And mass n of the monomer having a hydroxyl group used in the acrylic polymer (A)OH(mol) and number N of hydroxyl groupsOH(ii) is calculated by the following formula (1).
EOH＝nOH×NOH×1000/WA···(1)
The acrylic polymer (a) can be obtained by polymerizing the monomer components (preferably, the monomer components containing the (meth) acrylate (a1) and the monomer having an active hydrogen group (a2) as main components). As a polymerization method of the acrylic polymer (a), for example, solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, or the like can be employed. Among them, solution polymerization is preferable from the viewpoint of obtaining the acrylic polymer (a) in the form of a solution and facilitating use as a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition can be obtained by blending at least the compound (B) described later and the crosslinking agent (C) in a solution containing the acrylic polymer (a).
As the organic solvent used in the solution polymerization, an organic solvent generally used in the synthesis of an acrylic polymer can be used. Examples of such an organic solvent include ester solvents, ketone solvents, alcohol solvents, ether solvents, aromatic hydrocarbon solvents, and aliphatic hydrocarbon solvents. Specific examples of the organic solvent include ethyl acetate, acetone, methyl ethyl ketone, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, toluene, benzene, n-hexane, and the like.
As the polymerization initiator used for the polymerization of the acrylic polymer (a), a polymerization initiator generally used for the synthesis of acrylic polymers can be used. Examples of such a polymerization initiator include azo initiators such as azobisisobutyronitrile and 2, 2' -azobis (2, 4-dimethylvaleronitrile), peroxide initiators such as t-butyl hydroperoxide and benzoyl peroxide, and the like. The polymerization initiator may be used alone in 1 kind, or may be used in combination of 2 or more kinds. In the polymerization of the acrylic polymer (a), if necessary, the acrylic polymer (a) having a desired molecular weight can be obtained by using a catalyst or a polymerization inhibitor in combination, adjusting the polymerization temperature and the polymerization time, and the like.
From the viewpoint of the function as a component of the base polymer of the pressure-sensitive adhesive composition, the weight average molecular weight (Mw) of the acrylic polymer (a) is preferably 10 to 150 ten thousand, more preferably 10 to 120 ten thousand, and further preferably 10 to 100 ten thousand. The weight average molecular weight (Mw) is a standard polystyrene conversion value measured by Gel Permeation Chromatography (GPC).
The glass transition point (Tg) of the acrylic polymer (A) is preferably-70 to 0 ℃, more preferably-60 to 0 ℃, and still more preferably-50 to-10 ℃. In the present specification, when the acrylic polymer (a) is a homopolymer, the Tg of the acrylic polymer (a) is a value measured by DSC. When the acrylic polymer (a) is a copolymer, the Tg of the acrylic polymer (a) is a theoretical value determined from the following FOX formula (2) using the Tg of the homopolymer.
1/Tg＝W1/Tg1+W2/Tg2+···Wn/Tgn···(2)
In the above formula (2), Tg represents the glass transition point (K) of a copolymer of n monomer components (monomers 1 to n), W1、W2、···WnDenotes the mass fraction of the monomers (1, 2,. cndot. cndot.) relative to the total amount of the n monomer components, Tg1、Tg2、···TgnThe glass transition point (K) of the homopolymer of each monomer (1, 2,. cndot. cndot. For example, if the monomers used in the examples described later are cited as examples, the glass transition points of homopolymers of the monomers are as follows, and these values are used to calculate the Tg of the acrylic polymer produced in the examples described later.
Butyl Acrylate (BA): -52 deg.C
Ethyl Acrylate (EA): -22 deg.C
Methyl Acrylate (MA): 8 deg.C
Hydroxyethyl acrylate (HEA): -15 deg.C
Acrylic acid (AAc): 106 deg.C
The content of the acrylic polymer (a) in the pressure-sensitive adhesive composition is preferably 30 to 80% by mass, more preferably 40 to 70% by mass, based on the mass of the solid content of the pressure-sensitive adhesive composition.
[ Compound (B) ]
An adhesive composition according to an embodiment of the present invention contains a compound (B): the acrylic polymer (A) has a functional group which reacts with the active hydrogen group in the acrylic polymer (A) and has a carbon-carbon double bond, and the rate of change in mass when heated at 90 ℃ for 5 minutes is 5% or less.
The mass change rate of the compound (B) when heated at 90 ℃ for 5 minutes can be determined as follows: the compound (B) was heated at 90 ℃ for 5 minutes in a thermostatic bath, and the mass of the compound (B) before and after the test was measured, and the mass was determined from the following formula (3).
[ Pre-test quality-post-test quality ]/Pre-test quality X100 (%). The (3)
The compound (B) is a substance which imparts a carbon-carbon double bond to the acrylic polymer (A) which contributes to the formation of the adhesive. If a reactant obtained by reacting the acrylic polymer (a) and the compound (B) in advance is used for the adhesive composition and applied to form the adhesive, the reactant is advantageous for forming the adhesive. The compound (B) used in this manner is not a substance which imparts a carbon-carbon double bond to the acrylic polymer (A) which contributes to the formation of the adhesive. The fact that the compound (B) is "a compound which imparts a carbon-carbon double bond to the acrylic polymer (a) which contributes to the formation of the adhesive" means that, when the adhesive composition is applied to form the adhesive, the acrylic polymer (a) is used in a stage before the reaction with the compound (B) proceeds, and the compound (B) reacts to bond the acrylic polymer (a) and imparts a carbon-carbon double bond to the acrylic polymer (a) in a stage after the adhesive composition is applied and a stage in which the adhesive is formed (for example, a stage of drying, aging, or the like).
Here, the case where a reaction product obtained by previously reacting the acrylic polymer (a) with a compound having a carbon-carbon double bond and a functional group, such as the compound (B), is used in the adhesive composition to form the adhesive will be further described. The reaction between the acrylic polymer (A) and a compound having a carbon-carbon double bond and a functional group such as the compound (B) can be carried out at a temperature of, for example, about 40 to 60 ℃. In the above case, it is considered that, in order to sufficiently reduce the adhesive force of the pressure-sensitive adhesive after the irradiation with the active energy ray, the acrylic polymer (a) is previously reacted with a compound having a carbon-carbon double bond and a functional group, and a large number of carbon-carbon double bonds are introduced in advance. However, when a large number of carbon-carbon double bonds are introduced into the acrylic polymer (a) in advance, gelation is likely to occur. When the acrylic polymer (a) is gelled, the coating cannot be performed, and the use as a pressure-sensitive adhesive composition becomes difficult, and therefore gelation must be avoided. Therefore, the amount of the compound for introducing a carbon-carbon double bond into the acrylic polymer (a) must be suppressed, and the amount of the carbon-carbon double bond that can be introduced into the acrylic polymer (a) is limited.
Then, the present inventors have studied to prepare an adhesive composition by compounding the acrylic polymer (a), the compound having a carbon-carbon double bond and a functional group, and a crosslinking agent and the like, and then coat and dry the composition to form an adhesive when forming an adhesive. It is known that, according to this means, carbon-carbon double bonds can be introduced into the acrylic polymer (a) which contributes to the formation of the pressure-sensitive adhesive when the pressure-sensitive adhesive composition is dried, cured or the like after being applied, and the above-mentioned gelation can be avoided. However, it is known that the adhesive prepared in this manner may have insufficient adhesive strength after irradiation with active energy rays. This is considered to be because the above-mentioned compound evaporates when the pressure-sensitive adhesive composition is dried after being coated, and carbon-carbon double bonds cannot be efficiently introduced into the acrylic polymer (a).
Therefore, as a result of studies by the present inventors, in the pressure-sensitive adhesive composition according to one embodiment of the present invention, the compound (B) having a carbon-carbon double bond and a functional group reactive with an active hydrogen group is used, and the mass change rate when heated at 90 ℃ for 5 minutes is 5% or less. Since the above-mentioned mass change rate of the compound (B) is 5% or less, the adhesive composition is less likely to evaporate when dried after application, and therefore, carbon-carbon double bonds can be efficiently introduced into the acrylic polymer (a). Even in the case of a compound having a carbon-carbon double bond and a functional group reactive with an active hydrogen group, if the above-mentioned mass change rate of the compound exceeds 5%, the compound may evaporate during application and drying of the pressure-sensitive adhesive composition, and the carbon-carbon double bond may not be efficiently introduced into the acrylic polymer (a).
In order to effectively reduce the adhesive force of an adhesive formed of an adhesive composition by irradiating an active energy ray to the adhesive, it is necessary to use a specific amount of the compound (B) to the acrylic polymer (a). Specifically, the equivalent weight of the carbon-carbon double bond of the compound (B) must be 1.9meq/g or more relative to the acrylic polymer (A), or the content of the compound (B) must be 30 to 150 parts by mass relative to 100 parts by mass of the acrylic polymer (A), or both of them may be satisfied.
From the viewpoint of more effectively exhibiting the above-mentioned effects, the equivalent of the carbon-carbon double bond of the compound (B) is preferably 1.9meq/g or more and 4.0meq/g or less, and the lower limit thereof is more preferably 2.0meq/g or more, relative to the acrylic polymer (A). In the present specification, the equivalent of the carbon-carbon double bond of the compound (B) to the acrylic polymer (a) is a milliequivalent (meq/g) of the carbon-carbon double bond of the compound (B) per 1g of the acrylic polymer (a) in the pressure-sensitive adhesive composition, and is a calculated value calculated from the charged amount of the raw material. Specifically, the equivalent E (meq/g) of the carbon-carbon double bond can be calculated as follows: from the mass W of the acrylic polymer (A) contained in the adhesive compositionA(g) And mass n of compound (B) contained in the binder compositionBThe number N (mol) of carbon-carbon double bonds and (C-C) are calculated by the following formula (4).
E＝nB×N×1000/WA···(4)
From the viewpoint of more effectively exhibiting the above-described effects, the content of the compound (B) in the adhesive composition is preferably 30 to 130 parts by mass, more preferably 40 to 120 parts by mass, and still more preferably 50 to 100 parts by mass, based on 100 parts by mass (solid content) of the acrylic polymer (a).
Examples of the carbon-carbon double bond of the compound (B) include a carbon-carbon double bond in a (meth) acryloyl group, a vinyl group, and the like. The compound (B) preferably has a (meth) acryloyl group as a group containing a carbon-carbon double bond, and more preferably has a (meth) acryloyl group at a single terminal. The compound (B) can impart a carbon-carbon double bond by imparting a (meth) acryloyl group to the acrylic polymer (a) which contributes to the formation of an adhesive.
Examples of the functional group in the compound (B) which reacts with the active hydrogen group of the acrylic polymer (a) include an isocyanate group, an epoxy group, and a carbodiimide group. The compound (B) preferably has an isocyanate group as a functional group reactive with an active hydrogen group, and more preferably has an isocyanate group at a single terminal. The compound (B) further preferably has a (meth) acryloyl group at one single end and an isocyanate group at the other single end.
As described above, the compound (B) is preferably a reaction product of the monomer (B1) having a (meth) acryloyl group and a hydroxyl group and the polyfunctional isocyanate (B2), from the viewpoint that the mass change rate when the compound (B) is heated at 90 ℃ for 5 minutes is 5% or less.
As the monomer (b1), a (meth) acrylate having a hydroxyl group can be used, and 1 or 2 or more thereof can be used. Specific examples of the "monomer having a hydroxyl group" in the description of the acrylic polymer (a) are (meth) acrylates having a hydroxyl group. Among the monomers having a hydroxyl group as the monomer (b1), the hydroxyalkyl (meth) acrylate is preferable, 2-hydroxyethyl (meth) acrylate is more preferable, and 2-hydroxyethyl (meth) acrylate is even more preferable.
The polyfunctional isocyanate (b2) used in the above reaction product is a polyisocyanate compound having 2 or more isocyanate groups in 1 molecule. Among the above-mentioned reactants, 1 or 2 or more species of the polyfunctional isocyanate (b2) may be used. Examples of the polyfunctional isocyanate (b2) include: hexamethylene Diisocyanate (HDI), Xylene Diisocyanate (XDI), Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), and (1, 4-cyclohexanediyl) diisocyanate (H)6XDI), etc.; trimethylolpropane (TMP) adduct of a diisocyanate compound; process for producing diisocyanate compoundAn isocyanurate body; a biuret body of HDI; and allophanate of HDI. Among these, diisocyanate compounds are preferable, and HDI is more preferable.
As described above, as the compound (B), a reactant of hydroxyalkyl (meth) acrylate and a diisocyanate compound is more preferable, and a reactant of 2-hydroxyethyl acrylate and hexamethylene diisocyanate is particularly preferable. The reactant may be a polymer.
[ crosslinking agent (C) ]
The pressure-sensitive adhesive composition of one embodiment of the present invention contains a crosslinking agent (C) having 2 or more functional groups reactive with the active hydrogen groups of the acrylic polymer (a). When the pressure-sensitive adhesive composition is applied to form a pressure-sensitive adhesive, the active hydrogen group of the acrylic polymer (a) and the functional group of the crosslinking agent (C) may be subjected to a crosslinking reaction during drying, curing or the like after the pressure-sensitive adhesive composition is applied. This makes it possible to impart an appropriate adhesive force to the adhesive formed of the adhesive composition before the irradiation with the active energy ray.
Examples of the 2 or more functional groups of the crosslinking agent (C) include isocyanate groups and epoxy groups. Examples of the crosslinking agent (C) include polyisocyanate-based crosslinking agents and epoxy-based crosslinking agents, and 1 or 2 or more of these crosslinking agents can be used. As the crosslinking agent (C), a polyisocyanate compound (polyisocyanate-based crosslinking agent) having 2 or more isocyanate groups in 1 molecule is more preferably used.
As the polyisocyanate-based crosslinking agent, the same specific examples as those of the polyfunctional isocyanate (B2) listed in the description of the compound (B) can be used. Examples thereof include HDI, XDI, TDI, MDI, IPDI and H6Diisocyanate compounds such as XDI; an adduct of a diisocyanate compound; an isocyanurate body of a diisocyanate compound; a biuret body of HDI; and allophanate of HDI. Among them, 1 or 2 or more polyisocyanate-based crosslinking agents are preferably used. Among them, as the crosslinking agent (C), 1 or 2 or more selected from the group consisting of an adduct of a diisocyanate compound and an isocyanurate body, and a biuret body of HDI are more preferableThe above.
The equivalent weight of the isocyanate group of the crosslinking agent (C) is preferably 0.1 to 1.5meq/g, more preferably 0.1 to 1.2meq/g, and still more preferably 0.2 to 1.0meq/g, based on the acrylic polymer (A). In the present specification, the equivalent of the isocyanate group of the crosslinking agent (C) to the acrylic polymer (a) is a milliequivalent (meq/g) of the isocyanate group of the crosslinking agent (C) per 1g of the acrylic polymer (a) in the pressure-sensitive adhesive composition, and is a calculated value calculated from the charged amount of the raw material. Specifically, the equivalent E of the isocyanate group of the crosslinking agent (C)NCO(meq/g) can be calculated as follows: from the mass W of the acrylic polymer (A) contained in the adhesive compositionA(g) And mass n of crosslinking agent (C) (polyisocyanate compound)C(mol) and the number of isocyanate groups NNCO(ii) is calculated by the following formula (5).
ENCO＝nC×NNCO×1000/WA···(5)
The content of the crosslinking agent (C) in the adhesive composition is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 25 parts by mass, and still more preferably 1 to 20 parts by mass, based on 100 parts by mass (solid content) of the acrylic polymer (a). By applying, drying, curing, or the like to the pressure-sensitive adhesive composition in which the content of the crosslinking agent (C) in the pressure-sensitive adhesive composition is within the above range, a pressure-sensitive adhesive having appropriate adhesive force and cohesive force before irradiation with active energy rays can be formed.
The pressure-sensitive adhesive composition according to an embodiment of the present invention may contain a crosslinking agent other than the crosslinking agent (C) (hereinafter, sometimes referred to as "other crosslinking agent"). Examples of the other crosslinking agent include: aziridine-based crosslinking agents, melamine resin-based crosslinking agents, urea resin-based crosslinking agents, acid anhydride-based crosslinking agents, polyamine-based crosslinking agents, metal chelate-based crosslinking agents, carbodiimide-based crosslinking agents, and the like. 1 or 2 or more of the other crosslinking agents may be used. Among the other crosslinking agents, a metal chelate crosslinking agent is preferable.
Examples of the metal chelate-based crosslinking agent include metal chelate compounds such as aluminum chelate compounds, zirconium chelate compounds, and titanium chelate compounds. Among them, aluminum chelate compounds are more preferable.
The content of the other crosslinking agent in the adhesive composition is preferably 1 part by mass or less (0 to 1 part by mass), preferably 0.1 part by mass or less (0 to 0.1 part by mass), and more preferably 0.05 part by mass or less (0 to 0.05 part by mass) with respect to 100 parts by mass of the acrylic polymer (a).
The adhesive composition according to an embodiment of the present invention preferably further contains a polyfunctional monomer (D) having 2 or more carbon-carbon double bonds. When an active energy ray is irradiated to a pressure-sensitive adhesive formed from a pressure-sensitive adhesive composition containing the components (a) to (C) and further containing a polyfunctional monomer (D), the adhesive strength of the pressure-sensitive adhesive can be more effectively reduced by 2 or more carbon-carbon double bonds of the polyfunctional monomer (D).
The number of carbon-carbon double bonds in the polyfunctional monomer (D) is preferably 2 to 6. Examples of the carbon-carbon double bond include a carbon-carbon double bond in a (meth) acryloyl group, a vinyl group and the like. The polyfunctional monomer (D) preferably has 2 or more (meth) acryloyl groups as a group containing a carbon-carbon double bond, and more preferably has 2 or more acryloyl groups.
Examples of the polyfunctional monomer (D) include: di (meth) acrylate compounds such as 1, 3-butanediol di (meth) acrylate, 1, 4-butanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and ethoxylated bisphenol a di (meth) acrylate; and compounds having at least 3 (meth) acryloyl groups such as trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, ethylene oxide-modified trimethylolpropane tri (meth) acrylate, propylene oxide-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and glycerol tri (meth) acrylate. They may be used alone or in combination of 2 or more. Among these, it is preferable to use either or both of dipentaerythritol penta (meth) acrylate and dipentaerythritol hexa (meth) acrylate, and it is more preferable to use either or both of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate.
When the polyfunctional monomer (D) is contained in the adhesive composition, the content of the polyfunctional monomer (D) in the adhesive composition is preferably 20 to 90 parts by mass, more preferably 30 to 80 parts by mass, and still more preferably 40 to 80 parts by mass, based on 100 parts by mass of the acrylic polymer (a).
[ photoinitiator (E) ]
The adhesive composition according to an embodiment of the present invention preferably contains a photoinitiator (E). Thus, the photoinitiator may be present in advance in the adhesive formed by coating, drying, curing, or the like of the adhesive composition. When the pressure-sensitive adhesive is irradiated with light such as ultraviolet light, a curing reaction can be efficiently caused in the carbon-carbon double bond of the compound (B) bonded to the acrylic polymer (a) in the pressure-sensitive adhesive, and the adhesive strength of the pressure-sensitive adhesive can be effectively reduced.
For example, if an electron beam or the like is used as the active energy ray, the curing reaction can be caused even if the adhesive composition does not contain a photoinitiator in advance, and the adhesive force of the adhesive can be reduced. On the other hand, if a photoinitiator is contained in the pressure-sensitive adhesive composition in advance, the pressure-sensitive adhesive composition can be used as a pressure-sensitive adhesive for a wide range of applications from the viewpoints of facilities for use, restrictions, and the like, as described above, as long as light such as ultraviolet light and visible light can be used as an active energy ray.
The photoinitiator (E) is not particularly limited as long as it is a compound that generates a radical that is advantageous for initiating radical polymerization by irradiation with light such as near infrared light, visible light, and ultraviolet light. Examples of the photoinitiator (E) include: benzoin alkyl ether initiators such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; aromatic ketal initiators such as benzil dimethyl ketal; benzophenone-based initiators such as benzophenone, benzoylbenzoic acid, and 3, 3' -dimethyl-4-methoxybenzophenone; aromatic ketone initiators such as α -hydroxycyclohexyl phenyl ketone, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α -hydroxy- α, α' -dimethylacetophenone, methoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 2-diethoxyacetophenone, and 2-methyl-1- [4- (methylthio) -phenyl ] -2-morpholinyl-1-propanone; thioxanthone-based initiators such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2-dodecylthioxanthone, 2, 4-dichlorothioxanthone, 2, 4-dimethylthioxanthone, 2, 4-diethylthioxanthone, and 2, 4-diisopropylthioxanthone; benzil initiators such as benzil; benzoin-based initiators such as benzoin; α -ketol compounds such as 2-methyl-2-hydroxypropiophenone; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; optically active oxime compounds such as 1-phenyl-1, 1-propanedione-2- (o-ethoxycarbonyl) oxime; acylphosphine oxide-based initiators such as 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide, and 2,4, 6-trimethylbenzoyl methoxyphenylphosphine oxide; and the like. They may be used alone or in combination of 2 or more.
The content of the photoinitiator (E) in the adhesive composition is preferably 0.01 to 10 parts by mass, and more preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the acrylic polymer (a).
The pressure-sensitive adhesive composition may contain various additives in addition to the above-mentioned components (A) to (E) according to the characteristics required for the purpose of adjusting the adhesive strength and the like. Examples of the additives include terpene-based, terpene-phenol-based, coumarone-indene-based, styrene-based, rosin-based, xylene-based, phenol-based, or petroleum-based tackifying resins, antioxidants, ultraviolet absorbers, fillers, pigments, and the like.
As described above in detail, the pressure-sensitive adhesive composition according to an embodiment of the present invention contains the acrylic polymer (a), the compound (B), and the crosslinking agent (C). Applying the adhesive compositionIn the case of forming the adhesive agent from cloth, the active hydrogen group of the acrylic polymer (a) may react with the functional group of the compound (B) and the functional group of the crosslinking agent (C) when the adhesive agent composition is dried and cured after being applied. Therefore, the adhesive composition can form an adhesive having an appropriate adhesive force and an appropriate cohesive force before the irradiation with the active energy ray. Specifically, based on the above adhesive composition, 180 ° peel adhesion force F to a stainless steel test plate can be formed1(adhesive force F before irradiation with active energy ray1) Preferably 50gf/25mm or more, more preferably 60gf/25mm or more.
In the adhesive composition, the equivalent weight of the carbon-carbon double bond of the compound (B) is 1.9meq/g or more relative to the acrylic polymer (A), or the content of the compound (B) is 30-150 parts by mass relative to 100 parts by mass of the acrylic polymer (A). Even if carbon-carbon double bonds are introduced into the acrylic polymer (a) in such an amount, the compound (B) imparts carbon-carbon double bonds to the acrylic polymer (a) which contributes to the formation of the binder, and thus the gelation of the acrylic polymer (a) can be suppressed. That is, since the reaction between the acrylic polymer (a) and the compound (B) can occur when the pressure-sensitive adhesive composition is dried and cured after being applied, the gelation of the acrylic polymer (a) can be suppressed. Further, since the compound (B) has a mass change rate of 5% or less when heated at 90 ℃ for 5 minutes and is hard to evaporate even when the adhesive composition is applied and dried, almost all of the compound (B) can be used for the reaction with the acrylic polymer (a) which is advantageous for forming the adhesive. Therefore, a carbon-carbon double bond can be efficiently introduced into the acrylic polymer (A).
Therefore, the adhesive formed from the adhesive composition is irradiated with active energy rays to cause a curing reaction with carbon-carbon double bonds, thereby more effectively reducing the adhesive force of the adhesive. Specifically, the adhesive composition can form a 180 DEG peel adhesion F to a stainless steel test plate after irradiation with an active energy ray2Preferably less than 50gf/25mm and is the aforementioned adhesive force F1Less than 0.2 times of the amount of the binder. The above adhesive force F2More preferably less than 30gf/mm, still more preferably less than 20gf/25mm, and still more preferably the adhesive force F10.15 times or less, and more preferably 0.1 times or less. The peel adhesion force (F) is1And F2) Can be prepared according to JIS Z0237: 2009 by the test method specified in 2009.
The adhesive composition of an embodiment of the present invention can be used, for example, as follows: an adherend to be coated with the adhesive; a release sheet for transferring the adhesive to an adherend; to a sheet-like substrate or the like used in a pressure-sensitive adhesive sheet to be attached to an adherend. Among them, the adhesive composition is more preferably used for an adhesive layer of a sheet-like substrate provided in an adhesive sheet. Examples of suitable adhesive sheets include adhesive sheets for semiconductor wafer processing, adhesive sheets for surface protection, and adhesive tapes.
< adhesive sheet >
An adhesive sheet according to an embodiment of the present invention includes: a sheet-like substrate; and a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition and provided on the sheet-like substrate. The form of the pressure-sensitive adhesive sheet includes a sheet form, a tape form, a film form, and the like, and the pressure-sensitive adhesive sheet in these forms can be formed by winding the sheet into a roll form. Further, the sheet may be cut or punched into an appropriate shape depending on the purpose of use.
The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet may be provided on one side (one side) of the sheet-like substrate or on both sides. The thickness of the adhesive layer provided on one surface of the sheet-like substrate is preferably 5 to 100 μm, more preferably 5 to 80 μm, and further preferably 5 to 50 μm.
Examples of the form of the sheet-like substrate include a sheet, a film, a foil, and a tape. As the sheet-like substrate, a substance that transmits active energy rays used for reducing the adhesive force of the adhesive layer in the adhesive sheet is preferably used. Examples of the material of the sheet-like substrate include: paper such as japanese paper, kraft paper, and crepe paper; fabrics such as woven and nonwoven fabrics; plastics such as polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyurethane, and ethylene-vinyl acetate copolymer; and the like. The thickness of the sheet-like substrate is not particularly limited, but is preferably 20 to 300. mu.m, more preferably 30 to 200. mu.m.
< method for producing adhesive >
The method for producing an adhesive according to an embodiment of the present invention is a method for producing an adhesive having reduced adhesive force by irradiation with active energy rays. The manufacturing method comprises the following steps: the pressure-sensitive adhesive composition is prepared by blending the acrylic polymer (A), the compound (B) and the crosslinking agent (C) in such an amount that the equivalent of the carbon-carbon double bond in the compound (B) is not less than 1.9meq/g relative to the acrylic polymer (A), or the content of the compound (B) is 30 to 150 parts by mass relative to 100 parts by mass of the acrylic polymer (A). The manufacturing method further includes the steps of: after the foregoing adhesive composition is prepared, the reaction of the active hydrogen groups is advanced after the adhesive composition is applied to a substrate before the reaction of the active hydrogen groups proceeds.
By the production method having the above-mentioned configuration, the crosslinking reaction between the active hydrogen groups of the acrylic polymer (a) and the functional groups of the crosslinking agent (C) can be carried out at the stage after the application of the pressure-sensitive adhesive composition or at the stage of forming the pressure-sensitive adhesive (for example, at the stage of drying, aging, or the like). Thus, an adhesive having an appropriate adhesive force and an appropriate aggregating force before irradiation with an active energy ray can be formed.
In the production method having the above-described configuration, the acrylic polymer (a) and the compound (B) can be reacted with each other in the stage after the application of the adhesive composition or in the stage of forming the adhesive (for example, in the stage of drying, aging, or the like) to impart a carbon-carbon double bond. Thus, even when the equivalent of the carbon-carbon double bond of the compound (B) is 1.9meq/g or more relative to the acrylic polymer (A), and the compound (B) is added in an amount of 30 to 150 parts by mass relative to 100 parts by mass of the acrylic polymer (A), gelation of the acrylic polymer (A) can be avoided. Further, since the compound (B) is hard to evaporate even when the adhesive composition is applied and dried, almost all of the compound (B) used in the adhesive composition can be used for the reaction with the acrylic polymer (a) after the adhesive composition is applied. Therefore, carbon-carbon double bonds can be efficiently introduced into the acrylic polymer (a) forming the binder, and as a result, a binder having an increased amount of carbon-carbon double bonds in the polymer forming the binder can be formed. By irradiating the adhesive with active energy rays, a curing reaction can be generated from the carbon-carbon double bond, and therefore, the adhesive force of the adhesive can be effectively reduced, so that the adhesive can be easily peeled.
Examples of the method for applying the adhesive composition to the substrate include roll coating, bar coating, screen coating, die coating, spin coating, blade coating, gravure coating, and spray coating.
The substrate to be coated with the adhesive composition is not particularly limited. Examples of the substrate include, in addition to an adherend to be provided with a pressure-sensitive adhesive, the following: a release sheet for transferring the pressure-sensitive adhesive to an adherend, and a sheet-like substrate used for the pressure-sensitive adhesive sheet. The adhesive sheet can be produced by using the sheet-like substrate as a substrate to be coated with an adhesive composition.
The method for producing a pressure-sensitive adhesive according to an embodiment of the present invention preferably includes the following steps (drying step): the pressure-sensitive adhesive composition is applied to a substrate before the reaction of the active hydrogen groups in the acrylic polymer (a) proceeds, and then the coated product of the pressure-sensitive adhesive composition is dried. In the drying step, the active hydrogen group of the acrylic polymer (a) can react with the functional groups of the compound (B) and the crosslinking agent (C). The drying temperature in the drying step is preferably 50 to 150 ℃, more preferably 50 to 130 ℃, and further preferably 60 to 120 ℃. The drying time in the drying step is preferably 10 seconds to 60 minutes, more preferably 10 seconds to 30 minutes, and still more preferably 10 seconds to 10 minutes.
Further, after the drying step, it is preferable to further include the following step (aging step): the coating of the adhesive composition is cured. In the aging step, the active hydrogen group of the acrylic polymer (a) can react with the functional groups of the compound (B) and the crosslinking agent (C). The temperature in the curing step is preferably 5 to 60 ℃, more preferably 10 to 50 ℃, and still more preferably 20 to 40 ℃. The humidity in the aging step is preferably 30 to 70% RH, more preferably 40 to 60% RH. The aging period is preferably 1 day or more, more preferably 2 days or more, and still more preferably 3 days or more.
As described above, the adhesive according to an embodiment of the present invention may have the following configuration.
[1] An adhesive composition for forming an adhesive having reduced adhesive force by irradiation with active energy rays, comprising: an acrylic polymer (a) having an active hydrogen group; a compound (B) having a functional group that reacts with the active hydrogen group and a carbon-carbon double bond, wherein the acrylic polymer (A) that contributes to the formation of the pressure-sensitive adhesive is provided with the carbon-carbon double bond, and the rate of change in mass when heated at 90 ℃ for 5 minutes is 5% or less; and a crosslinking agent (C) having 2 or more functional groups reactive with the active hydrogen groups, wherein the equivalent weight of the carbon-carbon double bond of the compound (B) is 1.9meq/g or more based on the acrylic polymer (A).
[2] An adhesive composition for forming an adhesive having reduced adhesive force by irradiation with active energy rays, comprising: an acrylic polymer (a) having an active hydrogen group; a compound (B) having a functional group that reacts with the active hydrogen group and a carbon-carbon double bond, wherein the acrylic polymer (A) that contributes to the formation of the pressure-sensitive adhesive is provided with the carbon-carbon double bond, and the rate of change in mass when heated at 90 ℃ for 5 minutes is 5% or less; and a crosslinking agent (C) having 2 or more functional groups reactive with the active hydrogen group, wherein the content of the compound (B) is 30 to 150 parts by mass per 100 parts by mass of the acrylic polymer (A).
[3] The adhesive composition according to the above [1] or [2], wherein the acrylic polymer (A) has either or both of a hydroxyl group and a carboxyl group as the active hydrogen group, and the compound (B) and the crosslinking agent (C) have an isocyanate group as a functional group reactive with the active hydrogen group.
[4] The pressure-sensitive adhesive composition according to any one of the above [1] to [3], wherein the acrylic polymer (A) has a hydroxyl group as the active hydrogen group, and the equivalent weight of the hydroxyl group of the acrylic polymer (A) is 0.5meq/g or more and 2.0meq/g or less.
[5] The adhesive composition according to any one of the above [1] to [4], wherein the content of the crosslinking agent (C) is 0.1 to 30 parts by mass with respect to 100 parts by mass of the acrylic polymer (A).
[6] The adhesive composition according to any one of the above [1] to [5], wherein the crosslinking agent (C) has an isocyanate group as the functional group, and the equivalent weight of the isocyanate group of the crosslinking agent (C) is 0.1meq/g or more and 1.5meq/g or less with respect to the acrylic polymer (A).
[7] The adhesive composition according to any one of the above [1] to [6], wherein the compound (B) is a reaction product of a hydroxyalkyl (meth) acrylate and a diisocyanate compound.
[8] The adhesive composition according to any one of the above [1] to [7], further comprising a polyfunctional monomer (D) having 2 or more carbon-carbon double bonds.
[9] The adhesive composition according to any one of the above [1] to [8], further comprising a photoinitiator (E).
[10]According to the above [1]]～[9]The adhesive composition as claimed in any one of the preceding claims, wherein the 180 ° peel adhesion force F of the adhesive to a stainless steel test plate150gf/25mm or more, and a 180 DEG peel adhesion F to the stainless steel test plate after the irradiation with the active energy ray2Less than 50gf/25mm and is the aforementioned adhesive force F1Less than 0.2 times of the total amount of the active ingredient.
The pressure-sensitive adhesive sheet according to an embodiment of the present invention may have the following configuration.
[11] An adhesive sheet comprising: a sheet-like substrate; and a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition according to any one of the above [1] to [10] and provided on the sheet-like substrate.
Further, the method for producing the adhesive according to the embodiment of the present invention may employ the following configuration.
[12] A method for producing an adhesive having reduced adhesive force by irradiation with active energy rays, comprising: a step of preparing an adhesive composition by blending an acrylic polymer (A) having an active hydrogen group, a compound (B) having a carbon-carbon double bond and a functional group reactive with the active hydrogen group and having a mass change rate of 5% or less when heated at 90 ℃ for 5 minutes, and a crosslinking agent (C) having 2 or more functional groups reactive with the active hydrogen group, in such an amount that the equivalent of the carbon-carbon double bond in the compound (B) is 1.9meq/g or more relative to the acrylic polymer (A), or in such an amount that the content of the compound (B) is 30 to 150 parts by mass relative to 100 parts by mass of the acrylic polymer (A); and a step of applying the pressure-sensitive adhesive composition to a substrate after the pressure-sensitive adhesive composition is prepared and before the reaction of the active hydrogen groups proceeds, and then proceeding with the reaction of the active hydrogen groups.
Examples
Further specific examples of the above-described embodiment of the present invention will be described below by referring to production examples, and comparative examples, but the present invention is not limited thereto. In the following description, "part" and "%" are based on mass (referred to as "part by mass" and "% by mass", respectively) unless otherwise specified.
< production of acrylic Polymer (A) >
Production example 1
The acrylic polymer a1 was produced using a reaction apparatus equipped with a reaction tank, a stirrer, a reflux condenser, a nitrogen gas inlet tube, a thermometer, and a dropping liquid tube. Specifically, 80 parts of ethyl acetate and 15 parts of methyl ethyl ketone as solvents and 0.15 part of azobisisobutyronitrile as an initiator were charged into a reaction tank in a reaction apparatus. In this reaction vessel, 41.5 parts of butyl acrylate (hereinafter, sometimes referred to as "BA"), 35.2 parts of ethyl acrylate (hereinafter, sometimes referred to as "EA"), 10 parts of methyl acrylate (hereinafter, sometimes referred to as "MA"), 12.5 parts of 2-hydroxyethyl acrylate (hereinafter, sometimes referred to as "HEA"), and 0.8 part of acrylic acid (hereinafter, sometimes referred to as "AAc") were added dropwise from a dropping tube over about 2 hours, and polymerized at about 80 ℃ for 7 hours under a nitrogen atmosphere. After completion of the reaction, the reaction mixture was cooled and diluted with ethyl acetate to obtain a solution of an acrylic polymer A1 (weight-average molecular weight 331000) having a solid content of 44.0%.
Production examples 2 to 6
In production examples 2 to 6, solutions (solid content 44.0%) of acrylic polymers a2 to a6 were obtained in the same manner as in production example 1 except that the amount (unit: part) of the monomer components (BA, EA, MA, HEA, and AAc) used in production example 1 was changed as shown in table 1. The amount of each monomer (unit: mol) shown in table 1 is calculated from the amount of each monomer (unit: part) such that BA is 128.17, EA is 100.12, MA is 86.09, HEA is 116.12, and AAc is 72.06 with respect to the molecular weight of each monomer. In addition, Table 1 shows the theoretical value of Tg (. degree. C.) of each acrylic polymer (A).
TABLE 1 monomer components and amounts thereof used in the production of acrylic polymers
Figure BDA0001857069130000241
< preparation of adhesive composition >
In the following examples and comparative examples, the following acrylic polymer (a), compound (B), crosslinking agent (C), aluminum chelate compound, polyfunctional monomer (D), and photoinitiator (E) were used, respectively.
Acrylic polymer (a): acrylic polymers A1 to A6 produced in production examples 1 to 6
Compound (B): compound having acryloyl group and isocyanate group and having a mass change rate of 0% when heated at 90 ℃ for 5 minutes (Polymer of 2-hydroxyethyl acrylate (HEA) and 1, 6-diisocyanatohexane (HDI); product name "Laromer PR 9000" manufactured by BASF corporation)
Crosslinking agent (C): 1 polyisocyanate-based crosslinking agent having 3 isocyanate groups in the molecule (biuret of Hexamethylene Diisocyanate (HDI); product name "Duranate 24A-100" manufactured by Asahi Kasei Co., Ltd.)
Aluminum chelate complexes: aluminum triacetylacetone (Kawaken Fine Chemicals Co., Ltd., product name "aluminum chelate A" manufactured by Ltd.)
Polyfunctional monomer (D): dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (dipentaerythritol pentaacrylate content: 40 to 50%, product name "Aronix M-400" manufactured by east Asia synthetic Co., Ltd.)
Photoinitiator (E): 2,4, 6-Trimethylbenzoyldiphenylphosphine oxide (product name "Speedcure TPO" manufactured by Lambson)
(examples 1 to 13 and comparative examples 1 to 10)
The adhesive compositions of examples 1 to 13 and comparative examples 1 to 10 were prepared by mixing the components (unit: part) shown in the upper stage of tables 2-1 to 2-4. In comparative examples 7 and 8, 2-acryloyloxyethyl isocyanate (hereinafter, sometimes referred to as "AOI"; product name "Karenz AOI" manufactured by Showa Denko K.K.) was used in place of compound (B). The AOI was heated at 90 ℃ for 5 minutes, and the mass change rate was 33.7%.
The amounts (100.0 parts) of the acrylic polymers A1 to A6 shown in tables 2-1 to 2-4 were used as solid components. The amount (unit: mol) of the compound (B) shown in the table was determined by assuming that the compound (B) used was HEA and HDI in a ratio of 1: 1 (molar ratio) of the monomer obtained by the reaction, and a molecular weight (284.32). The amount (unit: mol) of the crosslinking agent (C) used is a value calculated from the molecular weight (478.59) calculated assuming that the crosslinking agent (C) used is a biuret product (monomer) of HDI. The amount (unit: mol) of the polyfunctional monomer (D) is a value calculated from the molecular weight (554.29) calculated assuming that the content of dipentaerythritol pentaacrylate in the polyfunctional monomer (D) used is 45% and the content of dipentaerythritol hexaacrylate is 55%. Further, the amount (unit: mol) of AOI used was calculated from the molecular weight of AOI of 141.12.
The middle stage of tables 2-1 to 2-4 shows the milliequivalents of carbon-carbon double bonds (in the same table, "equivalents of double bonds") per 1g of the compound (B) (AOI in the case of comparative examples 7 and 8) of the acrylic polymer in the pressure-sensitive adhesive composition, the milliequivalents of hydroxyl groups of the acrylic polymer (in the same table, "equivalents of hydroxyl groups"), and the milliequivalents of isocyanate groups per 1g of the crosslinking agent (C) (in the same table, "equivalents of isocyanate groups").
< production of adhesive and adhesive sheet >
The adhesive compositions of the examples and comparative examples were applied to a PET film as a substrate. Subsequently, the PET film coated with the adhesive composition was put into a drier at 100 ℃ and dried for 1 minute, thereby removing the solvent in the adhesive composition to form an adhesive layer having a thickness of 20 μm. A releasable PET film (hereinafter referred to as a release film) having a thickness of 38 μm was stuck to the surface on which the pressure-sensitive adhesive layer was formed, and then the film was cured at 23 ℃ and 50% RH in the dark for 4 days. In this manner, the adhesive composition was applied to a substrate, and then dried and cured, thereby reacting the active hydrogen group of the acrylic polymer (a) with the isocyanate group of the compound (B) (AOI in the case of comparative examples 7 and 8) and the crosslinking agent (C), to prepare a sample for evaluation (adhesive sheet). Then, using the evaluation sample, the measurement of gel fraction and the measurement of adhesive force described below were performed. These results are shown in the lower stages of tables 2-1 to 2-4.
< determination of gel fraction >
The pressure-sensitive adhesive layer (pressure-sensitive adhesive coating) in the evaluation sample was weighed to 0.2g (the mass thereof was denoted as W)1) This was immersed in 50mL of ethyl acetate for 1 day. Thereafter, a 200-mesh wire gauze was weighed (its mass was W)2) Then, filtration is performed to extract soluble substances. Then, the insoluble fraction was dried to determine the mass (W) of the insoluble fraction3). From these measurement values, the gel fraction (%) was calculated by the following formula (6). The gel fraction (%) of the pressure-sensitive adhesive layer after the pressure-sensitive adhesive layer was irradiated with Ultraviolet (UV) and left to stand in an atmosphere of 23 ℃ and 50% RH for 1 hour was also measured in the same manner. The UV irradiation conditions in this case were set to be adhesive force F2The same applies to the measurement of (1).
Gel fraction (%) ═ W3-W2)/W1)×100···(6)
< determination of adhesion >
A test piece (adhesive sheet) having an adhesive layer on a PET film was produced by peeling a release film from a prepared sample for evaluation, cutting the film into a size of 80mm × 25mm, and adhering the test piece to one surface of a stainless steel (SUS) test plate, and the test piece was stretched at a rate of 300 mm/min in a 180 DEG direction under an environment of 23 ℃ and 50% RH by the test method specified in JIS Z0237: 2009 to measure the initial (before irradiation with active energy rays) peel adhesion force F to the stainless steel test plate1(gf/25mm)。
The surface of the test piece prepared in the same manner as described above on which the pressure-sensitive adhesive layer was formed was irradiated with Ultraviolet (UV) light from the PET film side, and after standing in an atmosphere of 23 ℃ and 50% RH for 1 hour, the peel adhesion force F to the surface was measured1Measurement of (2) peel adhesion F to a stainless test plate was measured in the same manner as2(gf/25 mm). For the ultraviolet irradiation, an electrodeless lamp D valve manufactured by fusion corporation was used, and the irradiation condition was set to a light amount of 800mJ/cm2。
TABLE 2-1 composition, Properties of the adhesive composition
Figure BDA0001857069130000281
TABLE 2-2 composition, Properties of the adhesive composition
Figure BDA0001857069130000291
TABLE 2-3 composition, Properties of the adhesive compositions
Figure BDA0001857069130000301
Tables 2-4 composition, Properties of adhesive compositions
Figure BDA0001857069130000311
As shown in tables 2-1 to 2-4, it was confirmed that: the adhesive compositions of the examples were all capable of forming an adhesive having a moderate adhesive force before ultraviolet irradiation. Further, the adhesive force F after the ultraviolet irradiation of the adhesive formed from the adhesive composition of this example2All of them are less than 50gf/25mm, and are adhesive force F before ultraviolet irradiation1Less than 0.2 times of the total amount of the active ingredient. From these results, it was confirmed that: the adhesive compositions of the examples can each form an adhesive that can effectively reduce adhesive force by irradiating ultraviolet rays.

Claims (12)

1. An adhesive composition for forming an adhesive having reduced adhesive force by irradiation with active energy rays,
the adhesive composition contains:
an acrylic polymer (a) having an active hydrogen group;
a compound (B) having a carbon-carbon double bond and a functional group reactive with the active hydrogen group, the carbon-carbon double bond being imparted to the acrylic polymer (A) that contributes to the formation of the adhesive, and the rate of change in mass when heated at 90 ℃ for 5 minutes being 5% or less, wherein the functional group reactive with the active hydrogen group is at least one selected from the group consisting of an isocyanate group, an epoxy group, and a carbodiimide group; and the combination of (a) and (b),
a crosslinking agent (C) having 2 or more functional groups reactive with the active hydrogen groups,
the equivalent of the carbon-carbon double bond of the compound (B) is 1.9meq/g or more based on the acrylic polymer (A).
2. An adhesive composition for forming an adhesive having reduced adhesive force by irradiation with active energy rays,
the adhesive composition contains:
an acrylic polymer (a) having an active hydrogen group;
a compound (B) having a carbon-carbon double bond and a functional group reactive with the active hydrogen group, the carbon-carbon double bond being imparted to the acrylic polymer (A) that contributes to the formation of the adhesive, and the rate of change in mass when heated at 90 ℃ for 5 minutes being 5% or less, wherein the functional group reactive with the active hydrogen group is at least one selected from the group consisting of an isocyanate group, an epoxy group, and a carbodiimide group; and the combination of (a) and (b),
a crosslinking agent (C) having 2 or more functional groups reactive with the active hydrogen groups,
the content of the compound (B) is 30 to 150 parts by mass per 100 parts by mass of the acrylic polymer (A).
3. The adhesive composition according to claim 1 or 2, wherein the acrylic polymer (A) has either or both of a hydroxyl group and a carboxyl group as the active hydrogen group,
the compound (B) and the crosslinking agent (C) have an isocyanate group as a functional group reactive with the active hydrogen group.
4. The adhesive composition according to claim 1 or 2, wherein the acrylic polymer (A) has a hydroxyl group as the active hydrogen group,
the acrylic polymer (A) has a hydroxyl group equivalent of 0.5meq/g or more and 2.0meq/g or less.
5. The adhesive composition according to claim 1 or 2, wherein the content of the crosslinking agent (C) is 0.1 to 30 parts by mass with respect to 100 parts by mass of the acrylic polymer (a).
6. The adhesive composition according to claim 1 or 2, wherein the crosslinking agent (C) has an isocyanate group as the functional group,
the equivalent weight of the isocyanate group of the crosslinking agent (C) is 0.1meq/g or more and 1.5meq/g or less based on the acrylic polymer (A).
7. The adhesive composition according to claim 1 or 2, wherein the compound (B) is a reactant of a hydroxyalkyl (meth) acrylate and a diisocyanate compound.
8. The adhesive composition according to claim 1 or 2, further comprising a polyfunctional monomer (D) having 2 or more carbon-carbon double bonds.
9. The adhesive composition according to claim 1 or 2, further comprising a photoinitiator (E).
10. The adhesive composition of claim 1 or 2, wherein the adhesive has a 180 ° peel adhesion F to a stainless steel test plate1Is 50gf/25mm or more, and
180 DEG peel adhesion force F to the stainless steel test plate after the irradiation of the active energy ray2Less than 50gf/25mm and is the adhesive force F1Less than 0.2 times of the total amount of the active ingredient.
11. An adhesive sheet comprising: a sheet-like substrate; and an adhesive layer formed of the adhesive composition according to any one of claims 1 to 10 provided on the sheet-like substrate.
12. A method for producing an adhesive having reduced adhesive force by irradiation with active energy rays, comprising:
a step of preparing an adhesive composition by compounding an acrylic polymer (A) having an active hydrogen group, a compound (B) having a carbon-carbon double bond and a functional group reactive with the active hydrogen group and having a mass change rate of 5% or less when heated at 90 ℃ for 5 minutes, and a crosslinking agent (C) having 2 or more functional groups reactive with the active hydrogen group, in such an amount that the equivalent of the carbon-carbon double bond in the compound (B) is 1.9meq/g or more relative to the acrylic polymer (A), or in such an amount that the content of the compound (B) is 30 to 150 parts by mass relative to 100 parts by mass of the acrylic polymer (A), in the compound (B), the functional group reactive with the active hydrogen group is at least one selected from the group consisting of an isocyanate group, an epoxy group and a carbodiimide group; and the combination of (a) and (b),
a step of applying the adhesive composition to a substrate after the preparation of the adhesive composition and before the reaction of the active hydrogen groups proceeds, and then proceeding with the reaction of the active hydrogen groups.
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