Classifications

• • 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
  • C09J133/08—Homopolymers or copolymers of acrylic acid esters
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
• • 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
  • C09J143/00—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 containing boron, silicon, phosphorus, selenium, tellurium, or a metal; Adhesives based on derivatives of such polymers
  • C09J143/04—Homopolymers or copolymers of monomers containing silicon
• • 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
  • C09J183/00—Adhesives based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Adhesives based on derivatives of such polymers
  • C09J183/10—Block or graft copolymers containing polysiloxane sequences
• • 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
  • C09J201/00—Adhesives based on unspecified macromolecular compounds
• • 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
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
  • C09J2203/318—Applications of adhesives in processes or use of adhesives in the form of films or foils for the production of liquid crystal displays
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
  • C09J2203/326—Applications of adhesives in processes or use of adhesives in the form of films or foils for bonding electronic components such as wafers, chips or semiconductors
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J2433/00—Presence of (meth)acrylic polymer

Definitions

• the present invention relates to a pressure-sensitive adhesive composition, and a pressure-sensitive adhesive layer and a pressure-sensitive adhesive sheet that have the pressure-sensitive adhesive composition.
• a pressure-sensitive adhesive sheet is used for adhering adherends to each other or for fixing an article to an adherend by being firmly adhered to the adherend.
• a pressure-sensitive adhesive tape having the following characteristics is required: the pressure-sensitive adhesive force of which, occurring at the beginning of attachment, is small, because it is difficult to reattach the tape if the tape has large pressure-sensitive adhesive force from the beginning of attachment; while the pressure-sensitive adhesive force of which is increased over time such that large pressure-sensitive adhesive force can be obtained, in terms of fixing members in home electrical appliances and mobile devices, etc.
• Patent Documents 1 to 3 In order to meet such a change in pressure-sensitive adhesive force, methods for changing the pressure-sensitive adhesive force of pressure-sensitive adhesive sheets by heating or ultraviolet irradiation have traditionally been used (see Patent Documents 1 to 3).
• a pressure-sensitive adhesive sheet having the following properties is also required: when a pressure-sensitive adhesive sheet is peeled from an adherend, the adherend is hard to be contaminated or there is little adhesive deposit remaining on the adherend.
• Patent Document 1 Japanese Patent Application Publication No. 1999-302610
• Patent Document 2 Japanese Patent Application Publication No. 1999-302614
• Patent Document 3 Japanese Patent Application Publication No. 2011-127054
• the present invention has been made in view of these problems, and a purpose of the invention is to provide a pressure-sensitive adhesive in which reworkability to an adherend, an improvement in adhesiveness occurring over time, and a low contamination property can be entirely achieved.
• An aspect of the present invention is a pressure-sensitive adhesive composition.
• the pressure-sensitive adhesive composition comprises: 100 parts by mass of a polymer (A) having a glass transition temperature lower than 0° C.; and 0.1 to 20 parts by mass of a polymer (B) that contains, as monomer units, both a monomer having a functional group equivalent (Fge) of 1000 g/mol ⁇ Fge ⁇ 15000 g/mol and having a polyorganosiloxane skeleton and a monomer whose homopolymer has a glass transition temperature of 40° C. or higher, and that has a weight average molecular weight (MwB) of 10000 ⁇ MwB ⁇ 100000.
• Fge functional group equivalent
• MwB weight average molecular weight
• the polymer (A) may be an acrylic polymer.
• the polymer (B) may be a polymer containing, as a monomer unit, 10% by mass to 80% by mass of a monomer whose homopolymer has a glass transition temperature of 40° C. or higher.
• the monomer having a polyorganosiloxane skeleton may be one or more monomers selected from the group consisting of the monomers represented by the following general formula (1) or (2):
• R 3 is hydrogen or methyl
• R 4 is methyl or a monovalent organic group
• each of m and n is an integer of 0 or more.
• the pressure-sensitive adhesive layer is made of the pressure-sensitive adhesive composition according to any one of the aforementioned aspects.
• Still another aspect of the present invention is a pressure-sensitive adhesive sheet.
• the pressure-sensitive adhesive sheet is made by forming a pressure-sensitive adhesive layer of the aforementioned aspect on at least one surface of a supporting body.
• a pressure-sensitive adhesive composition according to an embodiment comprises a polymer (A) and a polymer (B).
• the polymer (A) is a polymer having a glass transition temperature lower than 0° C.
• the polymer (A) is not particularly limited as far as the glass transition temperature of which is lower than 0° C., and various polymers to be generally used as a pressure-sensitive adhesive, such as an acrylic polymer, rubber polymer, silicone polymer, polyurethane polymer, and polyester polymer, can be used.
• the polymer (B) is a (meth)acrylic polymer, an acrylic polymer, which is easily compatible with the (meth)acrylic polymer and has high transparency, is preferable.
• the glass transition temperature (Tg) of the polymer (A) is lower than 0° C., preferably lower than ⁇ 10° C., and more preferably lower than ⁇ 40° C. and usually ⁇ 80° C. or higher. If the glass transition temperature (Tg) of the polymer (A) is 0° C. or higher, it becomes difficult for the polymer to flow, and hence an increase in pressure-sensitive adhesive force occurring over time may be inferior.
• the glass transition temperature is a nominal value described in documents or catalogs, etc., or a value calculated based on the following equation (X) (Fox Equation).
• 1/ Tg W 1 /Tg 1 +W 2 /Tg 2 + . . . +W n /Tg n (X)
• Tg represents the glass transition temperature (unit: K) of the polymer (A)
• n represents the mass fraction of the monomer i based on the total monomer components.
• the “glass transition temperature when a homopolymer is formed” means the “glass transition temperature of a homopolymer of the monomer”, which means the glass transition temperature (Tg) of a polymer formed only by a monomer (sometimes referred to as a “monomer X”) as a monomer component. Specifically, those values are described in “Polymer Handbook” (Third Edition, John Wiley & Sons, Inc, 1989).
• the glass transition temperatures (Tg) of homopolymers which are not described in the above document, means the values obtained, for example, by the following measuring method.
• this homopolymer solution is caused to flow on a release liner to be coated thereon, and the solution is then dried to make a test sample (sheet-shaped homopolymer) having a thickness of approximately 2 mm.
• a test sample sheet-shaped homopolymer having a thickness of approximately 2 mm.
• 1 to 2 mg of this test sample is weighed and placed in an aluminum open cell, so that Reversing Heat Flow (specific heat component) behaviors of the homopolymer are obtained by using a temperature-modulated DSC (product name: “Q-2000” made by TA Instruments Inc.) at a heating rate of 5° C./min under 50 ml/min of a nitrogen flow rate atmosphere.
• a temperature-modulated DSC product name: “Q-2000” made by TA Instruments Inc.
• the temperature at the point where a straight line, located at the same distance in the vertical axis direction from a straight line obtained by extending the base line on the low-temperature side of the obtained Reversing Heat Flow and from a straight line obtained by extending the base line on the high-temperature side thereof, and a curved line, located at the portion where the glass transition temperature is changed in a stepwise shape, intersect with each other is determined to be the glass transition temperature (Tg) of the homopolymer.
• the weight average molecular weight (MwA) of the polymer (A) is, for example, approximately 30,000 to 5,000,000. If the weight average molecular weight (MwA) is less than 30,000, the cohesive force of a pressure-sensitive adhesive becomes insufficient, and hence adhesion reliability may be inferior. On the other hand, if the weight average molecular weight (MwA) is more than 5,000,000, the flow property of a pressure-sensitive adhesive becomes poor, and hence an increase in pressure-sensitive adhesive force occurring over time may be inferior.
• the acrylic polymer is a polymer containing, as a monomer unit, a (meth)acrylic acid alkyl ester having, for example, a C 1-20 linear or branched alkyl group in an amount of 50% by mass or more. Additionally, the acrylic polymer may have a structure formed by only a (meth)acrylic acid alkyl ester having a C 1-20 alkyl group or by a combination of two or more thereof.
• a method of obtaining the acrylic polymer is not particularly limited, but the polymer can be obtained by applying various polymerization methods that are generally used as a method of synthesizing an acrylic polymer, such as solution polymerization, emulsion polymerization, block polymerization, suspension polymerization, and radiation curing polymerization.
• the ratio of the (meth)acrylic acid alkyl ester having a C 1-20 linear or branched alkyl group to the total mass of the monomer components for preparing the acrylic polymer is 50% by mass to 99.9% by mass, preferably 60% by mass to 98% by mass, and more preferably 70% by mass to 95% by mass.
• Examples of the (meth)acrylic acid alkyl ester having a C 1-20 linear or branched alkyl group include (meth)acrylic acid C 1-20 alkyl esters (preferably (meth)acrylic acid C 2-14 alkyl esters, and more preferably (meth)acrylic acid C 2-10 alkyl esters), such as, for example, (meth)acrylic acid methyl, (meth)acrylic acid ethyl, (meth)acrylic acid propyl, (meth)acrylic acid isopropyl, (meth)acrylic acid butyl, (meth)acrylic acid isobutyl, (meth)acrylic acid s-butyl, (meth)acrylic acid t-butyl, (meth)acrylic acid pentyl, (meth)acrylic acid isopentyl, (meth)acrylic acid hexyl, (meth)acrylic acid heptyl, (meth)acrylic acid octyl,
• the (meth)acrylic acid alkyl ester means an acrylic acid alkyl ester and/or a methacrylic acid alkyl ester, and all of the “(meth) . . . ” expressions have the same meaning.
• the acrylic polymer may contain another monomer component (copolymerizable monomer) that is copolymerizable with the (meth)acrylic acid alkyl ester, if necessary, in order to improve cohesive force, heat resistance, and a bridging characteristic, etc. Accordingly, the acrylic polymer may contain a copolymerizable monomer along with the (meth)acrylic acid alkyl ester as a major component.
• a monomer having a polar group can be preferably used as the copolymerizable monomer.
• the copolymerizable monomer include: carboxyl group-containing monomers, such as acrylate, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid; hydroxyl group-containing monomers, such as (meth)acrylic acid hydroxyalkyls including (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 2-hydroxypropyl, (meth)acrylic acid 2-hydroxybutyl, (meth)acrylic acid 3-hydroxypropyl, (meth)acrylic acid 4-hydroxybutyl, (meth)acrylic acid 6-hydroxyhexyl, (meth)acrylic acid 8-hydroxyoctyl, (meth)acrylic acid 10-hydroxydecyl, (meth)acrylic acid 12-hydroxy lauryl, and (4-hydroxymethyl cyclohexyl)methyl methacrylate, etc.; acid
• the acrylic polymer contains, as a monomer unit, at least one monomer selected from the group consisting of N-vinyl cyclic amides represented by the following general formula (M1) and hydroxyl group-containing monomers. It is particularly preferable to use a monomer selected from the group consisting of the N-vinyl cyclic amides.
• N-vinyl cyclic amides include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazine-2-one, and N-vinyl-3,5-morpholinedione, etc. Among them, N-vinyl-2-pyrrolidone and N-vinyl-2-caprolactam are particularly preferred.
• the use amount of a monomer selected from the group consisting of N-vinyl cyclic amides is not particularly limited, but a copolymerizable monomer can be contained in an amount of usually 0.01% by mass to 40% by mass, preferably 0.1% by mass to 30% by mass, and more preferably 0.5% by mass to 20% by mass, based on the total mass of the monomer components for preparing the acrylic polymer.
• hydroxyl group-containing monomers As specific examples of the hydroxyl group-containing monomers, (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 4-hydroxybutyl, and (meth)acrylic acid 6-hydroxyhexyl, etc., can be preferably used.
• the use amount of the hydroxy group-containing monomer is not particularly limited, but a copolymerizable monomer can be used in an amount of usually 40% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass, based on the total mass of the monomer components for preparing the acrylic polymer.
• the copolymerizable monomer By containing 0.01% by mass or more of the copolymerizable monomer, it can be prevented that the cohesive force of the pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed by the acrylic pressure-sensitive adhesive composition may be decreased. Further, by containing 40% by mass or less of the copolymerizable monomer, it can be prevented that the cohesive force thereof may become too large, and the tackiness at normal temperature (25° C.) can be improved.
• the pressure-sensitive adhesive sheet when used in a metal adherend or an adherend on which a metal film is formed (e.g., a touch panel, etc., on which a conductive film (ITO) is formed), it is desirable that a carboxyl group is not contained in the acrylic polymer. Also, from the viewpoint of corrosiveness, it is desirable that acidic functional groups, other than a carboxyl group, are not substantially contained therein. Accordingly, the monomer units that form the acrylic polymer of the present embodiment may not substantially contain a monomer having a carboxyl group or an acidic functional group other than a carboxyl group.
• the acidic functional group means a functional group having active hydrogen.
• the acidic functional group include, for example, a carboxyl group, sulfonate group, phosphate group, etc.
• the expression that acidic functional groups “are not substantially contained” means that they are not actively combined, except the case where they are inevitably mixed. Specifically, it is meant that the ratio (% by mass) of a monomer having an acidic functional group to the total mass of units for forming the acrylic polymer is less than 1% by mass, and preferably less than 0.5% by mass.
• the acrylic polymer may contain, if necessary, a polyfunctional monomer for adjusting the cohesive force of the pressure-sensitive adhesive composition to be formed.
• polyfunctional polymer examples include, for example: (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylol methane tri(meth)acrylate, allyl(meth)acrylate, vinyl(meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyldiol(meth)acrylate
• trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate can be preferably used.
• the polyfunctional monomers can be used alone or in combination of two or more thereof.
• the use amount of the polyfunctional monomer is changed depending on the molecular weight or the number of functional groups thereof, but the polyfunctional monomer is added in an amount of 0.01% by mass to 3.0% by mass, preferably 0.02% by mass to 2.0% by mass, and more preferably 0.03% by mass to 1.0% by mass, based on the total mass of the monomer components for preparing the acrylic polymer.
• the use amount of the polyfunctional monomer is more than 3.0% by mass based on the total mass of the monomer components for preparing the acrylic polymer, for example, the cohesive force of a pressure-sensitive adhesive composition becomes too large, and hence the effect of suppressing the pressure-sensitive adhesive force in the early stage may be decreased.
• the use amount is less than 0.01% by mass, for example, the cohesive force of a pressure-sensitive adhesive composition is decreased, and hence an increase in pressure-sensitive adhesive force occurring over time may be insufficient.
• the acrylic polymer can be easily formed by a curing reaction using heat or ultraviolet rays with the use of a polymerization initiator, such as a thermal polymerization initiator, photo-polymerization initiator (photo-initiator), or the like.
• a polymerization initiator such as a thermal polymerization initiator, photo-polymerization initiator (photo-initiator), or the like.
• photo-polymerization can be preferably used from the advantage that a pressure-sensitive adhesive property is improved, etc.
• the polymerization initiators can be used alone or in combination of two or more thereof.
• thermal polymerization initiator examples include, for example: azo polymerization initiators (e.g., 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis(2-methylpropionic acid)dimethyl, 4,4′-azobis-4-cyanovalerianic acid, azobis isovaleronitrile, 2,2′-azobis(2-amidinopropane)dihydrochloride, 2,2′-azobis[2-(5-methyl-2-imidazoline-2-yl) propane]dihydrochloride, 2,2′-azobis(2-methylpropionamidine)disulfate, and 2,2′-azobis(N,N′-dimethyleneisobutylamidine)dihydrochloride, etc.); peroxide polymerization initiators (e.g., dibenzoyl peroxide, t-butyl permaleate, and lauroyl peroxide, etc.); redox
• the use amount of the thermal polymerization initiator is not particularly limited, but the thermal polymerization initiator is combined, for example, in an amount of 0.01 parts by mass to 5 parts by mass, and preferably 0.05 parts by mass to 3 parts by mass, based on 100 parts by mass of the monomer components for preparing the acrylic polymer.
• the photo-polymerization initiator is not particularly limited, but, for example, a benzoin ether photo-polymerization initiator, acetophenone photo-polymerization initiator, ⁇ -ketol photo-polymerization initiator, aromatic sulfonyl chloride photo-polymerization initiator, photoactive oxime photo-polymerization initiator, benzoin photo-polymerization initiator, benzyl photo-polymerization initiator, benzophenone photo-polymerization initiator, ketal photo-polymerization initiator, thioxanthone photo-polymerization initiator, acylphosphine oxide photo-polymerization initiator, or the like, can be used.
• a benzoin ether photo-polymerization initiator acetophenone photo-polymerization initiator, ⁇ -ketol photo-polymerization initiator, aromatic sulfonyl chloride photo-polymerization initiator, photo
• benzoin ether photo-polymerization initiator examples include, for example, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one [product name: IRGACURE 651 made by BASF], and Anisoin, etc.
• acetophenone photo-polymerization initiator examples include, for example, 1-hydroxycyclohexyl phenyl ketone [product name: IRGACURE 184, made by BASF], 4-phenoxy dichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one [product name: IRGACURE 2959, made by BASF], 2-hydroxy-2-methyl-1-phenyl-propane-1-one [product name: DAROCUR 1173, made by BASF], and methoxy acetophenone, etc.
• 1-hydroxycyclohexyl phenyl ketone product name: IRGACURE 184, made by BASF
• 4-phenoxy dichloroacetophenone 4-t-butyl-dichloroacetophenone
• ⁇ -ketol photo-polymerization initiator examples include, for example, 2-methyl-2-hydroxy propiophenone and 1-[4-(2-hydroxyethyl)-phenyl]-2-hydroxy-2-methylpropane-1-one, etc.
• aromatic sulfonyl chloride photo-polymerization initiator examples include, for example, 2-naphthalene sulfonyl chloride, etc.
• photoactive oxime photo-polymerization initiator include, for example, 1-phenyl-1,2-propanedione-2-(0-ethoxycarbonyl)-oxime, etc.
• benzoin photo-polymerization initiator examples include, for example, benzoin, etc.
• benzyl photo-polymerization initiator examples include, for example, benzyl, etc.
• benzophenone photo-polymerization initiators include, for example, benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinyl benzophenone, and ⁇ -hydroxy cyclohexyl phenyl ketone, etc.
• ketal photo-polymerization initiator examples include, for example, benzyl dimethyl ketal, etc.
• thioxanthone photo-polymerization initiator examples include, for example, thioxanthone, 2-chlorothioxanthone, 2-methyl thioxanthone, 2,4-dimethyl thioxanthone, isopropyl thioxanthone, 2,4-dichloro thioxanthone, 2,4-diethyl thioxanthone, isopropyl thioxanthone, 2,4-diisopropyl thioxanthone, and dodecyl thioxanthone, etc.
• acylphosphine photo-polymerization initiator include, for example, bis(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)(2,4,4-trimethylpentyl)phosphine oxide, bis(2,6-dimethoxybenzoyl)-n-butyl phosphine oxide, bis(2,6-dimethoxybenzoyl)-(2-methylpropane-1-yl)phosphine oxide, bis(2,6-dimethoxybenzoyl)-(1-methylpropane-1-yl)phosphine oxide, bis(2,6-dimethoxybenzoyl)-t-butylphosphine oxide, bis(2,6-dimethoxybenzoyl)cyclohexylphosphine oxide, bis(2,6-dimethoxybenzoyl)octylphosphine oxide, bis(2-methoxybenz
• the use amount of the photo-polymerization initiator is not particularly limited, but the photo-polymerization initiator is combined, for example, in an amount of 0.01 parts by mass to 5 parts by mass, and preferably 0.05 parts by mass to 3 parts by mass, based on 100 parts by mass of the monomer components for preparing the acrylic polymer.
• the use amount of the photo-polymerization initiator is less than 0.01 parts by mass, a polymerization reaction may become insufficient. If the use amount thereof is more than 5 parts by mass, an ultraviolet ray may not reach the inside of a pressure-sensitive adhesive layer, because the photo-polymerization initiator absorbs an ultraviolet ray. In this case, a rate of polymerization is decreased, or the molecular weight of the generated polymer becomes small. Thereby, the cohesive force of the pressure-sensitive adhesive layer formed becomes small, and hence an increase in pressure-sensitive adhesive force occurring over time may be insufficient.
• the photo-polymerization initiators can be used alone or in combination of two or more thereof.
• the polymer (A) can also be prepared as a partial polymer (acrylic polymer syrup) whose monomer components are partially polymerized by irradiating a mixture, in which the monomer components and the polymerization initiator have been blended, with ultraviolet (UV) rays.
• the polymerization of the acrylic polymer syrup can be completed by blending the later-described polymer (B) into the syrup to prepare a pressure-sensitive adhesive composition and then by coating the pressure-sensitive adhesive composition onto a predetermined object to be coated followed by irradiation of ultraviolet rays.
• the acrylic polymer syrup is a precursor of the polymer (A), and accordingly a composition, in which the polymer (B) has been blended into the acrylic polymer syrup, also corresponds to the pressure-sensitive adhesive composition of the present embodiment.
• the polymer (B) contains, as monomer units, both a monomer (B1) having a functional group equivalent (Fge) of 1000 g/mol ⁇ Fge ⁇ 15000 g/mol and having a polyorganosiloxane skeleton, and a monomer (B2) whose homopolymer has a glass transition temperature of 40° C. or higher.
• the monomer (B1) having a polyorganosiloxane skeleton that forms the polymer (B) is not particularly limited, but any polyorganosiloxane skeleton-containing monomer can be used. Uneven distribution of the polymer (B) to the surface of an adherend is actively promoted by the low polarity of the polyorganosiloxane skeleton-containing monomer, the low polarity being derived from the structure of the monomer, thereby allowing easy peelability to be demonstrated at the beginning of attachment.
• the polyorganosiloxane skeleton-containing monomer for example, the polyorganosiloxane skeleton-containing monomers represented by the following general formula (1) or (2) can be used. More specifically, one-terminal reactive silicone oil made by Shin-Etsu Chemical Co., Ltd., such as X-22-174ASX, X-22-174DX, X-22-2426, and X-22-2475, can be cited, which can be used alone or in combination of two or more thereof.
• R 3 is hydrogen or methyl
• R 4 is methyl or a monovalent organic group
• each of m and n is an integer of 0 or more.
• the functional group equivalent (Fge) of the monomer (B1) having a polyorganosiloxane skeleton that forms the polymer (B) is 1000 g/mol ⁇ Fge ⁇ 15000 g/mol. If the functional group equivalent (Fge) of the monomer (B1) having a polyorganosiloxane skeleton is Fge ⁇ 1000 g/mol, easy peelability is not be demonstrated, and pressure-sensitive adhesive force may not be reduced at the beginning of attachment.
• the functional group equivalent (Fge) of the monomer having a polyorganosiloxane skeleton is 15000 g/mol ⁇ Fge, the compatibility with the polymer (A) is remarkably deteriorated, and pressure-sensitive adhesive force may not be reduced at the beginning of attachment to an adherend or a property of increasing pressure-sensitive adhesive force occurring over time may be inferior.
• the “functional group equivalent” means the mass of a main skeleton (e.g., polydimethylsiloxane) bound to per functional group.
• the indicated unit of g/mol is obtained by converting into 1 mol of functional groups.
• the functional group equivalent of a monomer having a polyorganosiloxane skeleton is calculated from spectral intensities in 1 H-NMR (proton NMR) obtained, for example, by a nuclear magnetic resonance (NMR) apparatus.
• the ratio of the spectral intensity of H bound to Si of a siloxane structure via C (e.g., H in Si—(CH 3 ) 2 ) to the spectral intensity of H in a functional group of C—CH 3 , SH, or C ⁇ CH 2 is determined in 1 H-NMR obtained.
• the ratio of the spectral intensity of H in a siloxane structure of Si—(CH 3 ) 2 to that of H in a functional group of C ⁇ CH 2 can be determined from the ratio of the spectral intensities.
• the ratio (A/B) of the number A of the siloxane structures each having an Si—(CH 3 ) 2 bond to the number B of the functional groups, the siloxane structures and the functional groups being contained in the measurement sample can be determined from the ratio of the number of the siloxane structures of Si—(CH 3 ) 2 to the number of the functional groups of C ⁇ CH 2 .
• the content of the monomer (B1), having a functional group equivalent (Fge) of 1000 g/mol ⁇ Fge ⁇ 15000 g/mol and having a polyorganosiloxane skeleton, is 5% by mass or more but 50% by mass or less, preferably 10% by mass or more but 40% by mass or less, and more preferably 15% by mass or more but 30% by mass or less, based on the mass of the total monomer components of the polymer (B). If the content thereof is less than 5% by mass, adhesive force may not be reduced at the beginning of attachment. On the other hand, if the content is more than 50% by mass, pressure-sensitive adhesive force may not be reduced at the beginning of attachment or a property of increasing pressure-sensitive adhesive force over time may be inferior.
• Fge functional group equivalent
• Examples of the monomer (B2) whose homopolymer has a glass transition temperature of 40° C. or higher that forms the polymer (B) include (meth)acrylic monomers, such as, for example, dicyclopentanyl methacrylate (Tg: 175° C.), dicyclopentanyl acrylate (Tg: 120° C.), isobornyl methacrylate (Tg: 173° C.), isobornyl acrylate (Tg: 97° C.), methyl methacrylate (Tg: 105° C.), 1-adamantyl methacrylate (Tg: 250° C.), and 1-adamantyl acrylate (Tg: 153° C.). It is preferable that the homopolymer of the monomer (B-2) has a glass transition temperature of 80° C. or higher, and more preferably that the homopolymer has a glass transition temperature of 100° C. or higher.
• the polymer (B) may be a copolymer of the aforementioned(meth)acrylic monomer and the following monomer (however, the glass transition temperature of the homopolymer thereof is 40° C. or higher).
• the monomer copolymerizable with the aforementioned (meth)acrylic monomer include: amide group-containing vinyl monomers, such as acryloyl morpholine (Tg: 145° C.), dimethylacrylamide (Tg: 119° C.), diethylacrylamide (Tg: 81° C.), dimethylaminopropylacrylamide (Tg: 134° C.), isopropylacrylamide (Tg: 134° C.), and hydroxyethyl acrylamide (Tg: 98° C.); and lactam monomers, such as N-vinyl caprolactams including N-vinyl-2-caprolactam, etc.
• the content of the monomer (B2) whose homopolymer has a glass transition temperature of 40° C. or higher is preferably 10% by mass or more but 80% by mass or less, more preferably 20% by mass or more but 60% by mass or less, and still more preferably 30% by mass or more but 50% by mass or less, based on the mass of the total monomer components of the polymer (B). If the content is less than 10% by mass, pressure-sensitive adhesive force may not be reduced at the beginning of attachment. On the other hand, if the content is more than 80% by mass, a property of increasing pressure-sensitive adhesive force over time may be inferior.
• Pressure-sensitive adhesive force occurring at the beginning of attachment, can be controlled and pressure-sensitive adhesive force can be increased over time with a (meth)acrylic monomer whose homopolymer has a glass transition temperature of 40° C. or higher being contained in the polymer (B).
• the polymer (B) may contain a (meth)acrylic monomer whose homopolymer has a glass transition temperature lower than 80° C.
• the (meth)acrylic monomer whose homopolymer has a glass transition temperature lower than 80° C. include, for example, butyl methacrylate (Tg: 20° C.) and 2-ethylhexyl methacrylate (Tg: ⁇ 10° C.), etc.
• the polymer (B) may be a copolymer containing the monomer having a polyorganosiloxane skeleton, the (meth)acrylic monomer whose homopolymer has a glass transition temperature of 40° C. or higher, and one or more monomers selected from the group consisting of a (meth)acrylic monomer having an alicyclic structure, a monomer having a polyoxyalkylene skelton, a (meth)acrylic acid ester monomer, and a copolymerizable monomer.
• Examples of such a (meth)acrylic acid ester monomer include: (meth)acrylic acid alkyl esters, such as (meth)acrylic acid methyl, (meth)acrylic acid ethyl, (meth)acrylic acid propyl, (meth)acrylic acid isopropyl, (meth)acrylic acid butyl, (meth)acrylic acid isobutyl, (meth)acrylic acid s-butyl, (meth)acrylic acid t-butyl, (meth)acrylic acid pentyl, (meth)acrylic acid isopentyl, (meth)acrylic acid hexyl, (meth)acrylic acid-2-ethylhexyl, (meth)acrylic acid heptyl, (meth)acrylic acid octyl, (meth)acrylic acid isooctyl, (meth)acrylic acid nonyl, (meth)acrylic acid isononyl,
• the polymer (B) can also be obtained by copolymerizing, other than the (meth)acrylic acid ester component unit, another monomer component (copolymerizable monomer) copolymerizable with the (meth)acrylic acid ester.
• a functional group that is reactive with an epoxy group or an isocyanate group may be introduced into the polymer (B).
• examples of such a functional group include a hydroxyl group, carboxyl group, amino group, amide group, and mercapt group, and a monomer having such a functional group may be used (copolymerized) in producing the polymer (B).
• Examples of the another monomer that is copolymerizable with the (meth)acrylic acid ester include: carboxyl group-containing monomers, such as acrylic acid, methacrylic acid, carboxy ethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid; (meth)acrylic acid alkoxy alkyl monomers, such as (meth)acrylic acid methoxyethyl, (meth)acrylic acid ethoxyethyl, (meth)acrylic acid propoxyethyl, (meth)acrylic acid butoxyethyl, and (meth)acrylic acid ethoxypropyl; salts, such as (meth)acrylic acid alkali metal salt; di(meth)acrylic acid ester monomers of (poly)oxyalkylene, such as di(meth)acrylic acid ester of ethylene glycol, di(meth)acryl
• the content of other monomer components, other than the monomer (B1) having a polyorganosiloxane skeleton and the (meth)acrylic monomer (B2) whose homopolymer has a glass transition temperature of 40° C. or higher is preferably 0% by mass or more but 85% by mass or less, more preferably 0% by mass or more but 70% by mass or less, and still more preferably 20% by mass or more but 55% by mass or less, based on the mass of the total monomer components of the polymer (B).
• the weight average molecular weight (MwB) of the polymer (B) is 10000 ⁇ MwB ⁇ 100000, preferably 12000 ⁇ MwB ⁇ 50000, and more preferably 15000 ⁇ MwB ⁇ 30000. If the weight average molecular weight (MwB) of the polymer (B) is 100000 ⁇ MwB, pressure-sensitive adhesive force occurring at the beginning of attachment is not reduced. If the weight average molecular weight (MwB) is MwB ⁇ 10000, which is too low, the pressure-sensitive adhesive force of a pressure-sensitive adhesive sheet may not be increased over time.
• the weight average molecular weights of the polymer (A) and the polymer (B) can be determined by a gel permeation chromatography (GPC) method and by polystyrene conversion. Specifically, the measurement is performed in accordance with the method and conditions described in the later-described Examples.
• GPC gel permeation chromatography
• the polymer (B) can be produced by polymerizing the aforementioned monomers with, for example, a solution polymerization method, bulk polymerization method, emulsion polymerization method, suspension polymerization, block polymerization, or the like.
• a chain transfer agent can be used during the polymerization.
• the chain transfer agent to be used include: compounds having a mercapt group, such as octylmercaptan, laurylmercaptan, t-nonyl mercaptan, t-dodecyl mercaptan, mercaptoethanol, and ⁇ -thioglycerol; thioglycolic acid, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate
• the use amount of the chain transfer agent is not particularly limited, but is contained in an amount of usually 0.05 parts by mass to 20 parts by mass, preferably 0.1 parts by mass to 15 parts by mass, and more preferably 0.2 parts by mass to 10 parts by mass, based on 100 parts by mass of the monomer.
• the (meth)acrylic polymer (B) having a preferred molecular weight can be obtained.
• the chain transfer agents can be used alone or in combination of two or more thereof.
• the pressure-sensitive adhesive composition includes the aforementioned polymer (A) and the polymer (B) as essential components.
• the content of the polymer (B) is 0.1 parts by mass or more but 20 parts by mass or less, preferably 0.3 parts by mass part to 17 parts by mass, more preferably 0.4 parts by mass to 15 parts by mass, and still more preferably 0.5 parts by mass to 12 parts by mass, based on 100 parts by mass of the polymer (A). If the polymer (B) is added in an amount more than 20 parts by mass, the pressure-sensitive adhesive force of a pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition according to the present embodiment is decreased over time. Conversely, if the polymer (B) is added in an amount less than 0.1 parts by mass, the effect of suppressing pressure-sensitive adhesive force, occurring when an adherend is attached, is small, and a failure in which rework cannot be performed may be generated.
• the pressure-sensitive adhesive composition may contain, other than the aforementioned polymer (A) and polymer (B), various types of additives that are common in the field of pressure-sensitive adhesive compositions, as optional components.
• additives that are common in the field of pressure-sensitive adhesive compositions, as optional components.
• Such optional components are exemplified by a tackifying resin, cross-linking agent, catalyst, plasticizer, softener, filler, colorant (pigment, dye, or the like), antioxidant, leveling agent, stabilizer, antiseptic, and antistatic agent, etc.
• additives that are conventionally and publicly known can be used by ordinary methods.
• a cross-linking agent can also be used other than the aforementioned various monomers.
• Commonly-used cross-linking agents can be used as the cross-linking agent.
• the cross-linking agents include, for example, an epoxy cross-linking agent, isocyanate cross-linking agent, silicone cross-linking agent, oxazoline cross-linking agent, aziridine cross-linking agent, silane cross-linking gent, alkyl-etherified melamine cross-linking agent, and metal chelate cross-linking agent, etc.
• an isocyanate cross-linking agent, epoxy cross-linking agent, and metal chelate cross-linking agent can be preferably used. These compounds may be used alone or in combination of two or more thereof.
• isocyanate cross-linking agent examples include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethyl xylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, and adducts of these compounds with polyols such as trimethylolpropane.
• a compound having, in one molecule, at least one isocyanate group and one or more unsaturated bonds specifically 2-isocyanate ethyl(meth)acrylate, etc.
• These compounds may be used alone or in combination of two or more thereof.
• epoxy cross-linking agent examples include, bisphenol A, epichlorohydrin type epoxy resin, ethyleneglycidylether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N,N,N′,N′-tetraglycidyl-m-xylylenediamine, and 1,3-bis(N,N-diglycidyl aminomethyl)cyclohexane, etc. These compounds may be used alone or in combination of two or more thereof.
• metal chelate compound examples include: as metal components, aluminum, iron, tin, titanium, and nickel; and as chelate components, acetylene, methyl acetoacetate, and ethyl lactate, etc. These compounds may be used alone or in combination of two or more thereof.
• the cross-linking agent is preferably contained in an amount of 0.01 parts by mass to 15 parts by mass, and more preferably contained in an amount of 0.5 parts by mass to 10 parts by mass, based on 100 parts by mass of the polymer (A). If the content thereof is less than 0.01 parts by mass, the cohesive force of a pressure-sensitive adhesive composition becomes small, and hence adhesion reliability may be inferior. On the other hand, if the content is more than 15 parts by mass, the cohesive force of a pressure-sensitive adhesive composition becomes large and the flow property thereof becomes poor, and hence an increase in pressure-sensitive adhesive force occurring over time may be inferior.
• the pressure-sensitive adhesive composition disclosed herein may further include a cross-linking catalyst for further effectively promoting any one of the aforementioned cross-linking reactions.
• a cross-linking catalyst for example, a tin catalyst (in particular, dioctyl tin dilaurate) can be preferably used.
• the use amount of the cross-linking catalyst is not particularly limited, but the use amount may be, for example, approximately 0.0001 parts by mass to 1 part by mass, based on 100 parts by mass of the polymer (A).
• the tackifying resin is not particularly limited. Examples thereof include, for example, a rosin tackifying resin, terpene tackifying resin, phenol tackifying resin, hydrocarbon tackifying resin, ketone tackifying resin, polyamide tackifying resin, epoxy tackifying resin, and elastomer tackifying resin, etc.
• rosin tackifying resin examples include, for example, unmodified rosin (raw rosin), such as gum rosin, wood rosin, and tall oil rosin; modified rosins obtained by modifying these unmodified rosin with polymerization, disproportionation, and hydrogenation, etc. (polymerized rosin, stabilized rosin, disproportionated rosin, completely hydrogenated rosin, partially hydrogenated rosin, and chemically modified other rosin, etc.); and various rosin derivatives.
• unmodified rosin raw rosin
• modified rosins obtained by modifying these unmodified rosin with polymerization, disproportionation, and hydrogenation, etc.
• polymerized rosin, stabilized rosin, disproportionated rosin, completely hydrogenated rosin, partially hydrogenated rosin, and chemically modified other rosin, etc. polymerized rosin, stabilized rosin, disproportionated rosin, completely hydrogenated rosin, partially
• rosin derivatives include, for example: rosin phenol resins obtained by adding phenol to rosins (unmodified rosin, modified rosin, and various rosin derivatives, etc.) with an acid catalyst followed by being subjected to thermal polymerization; rosin ester resins, such as rosin ester compounds (unmodified rosin esters) obtained by esterifying unmodified rosin with alcohols, and modified rosin ester compounds (such as polymerized rosin ester, stabilized rosin ester, disproportionated rosin ester, completely hydrogenated rosin ester, and partially hydrogenated rosin ester) obtained by esterifying modified rosin (such as polymerized rosin, stabilized rosin, disproportionated rosin, completely hydrogenated rosin, and partially hydrogenated rosin) with alcohols; unsaturated fatty acid-modified rosin resins obtained by modifying unmodified rosin or modified rosin (polymerized rosin) with
• terpene tackifying resin examples include, for example: terpene resins, such as an ⁇ -pinene polymer, ⁇ -pinene polymer, and dipentene polymer; modified terpene resins obtained by modifying (phenol modification, aromatic modification, hydrogenation modification, and hydrocarbon modification, etc.) these terpene resins (e.g., a terpene phenol resin, styrene modified terpene resin, aromatic modified terpene resin, and hydrogenated terpene resin, etc.); and the like.
• terpene resins such as an ⁇ -pinene polymer, ⁇ -pinene polymer, and dipentene polymer
• modified terpene resins obtained by modifying (phenol modification, aromatic modification, hydrogenation modification, and hydrocarbon modification, etc.) these terpene resins (e.g., a terpene phenol resin, styrene modified terpene resin, aromatic modified terpene resin, and
• phenol tackifying resin examples include, for example: condensates of various phenols (e.g., phenol, m-cresol, 3,5-xylenol, p-alkylphenol, and resorcinol, etc.) and formaldehydes (e.g., an alkylphenol resin and xyleneformaldehyde resin, etc.); resols obtained by subjecting the phenols and the formaldehydes to an addition reaction with an alkali catalyst; novolacs obtained by subjecting the phenols and the formaldehydes to a condensation reaction with an acid catalyst; and the like.
• phenols e.g., phenol, m-cresol, 3,5-xylenol, p-alkylphenol, and resorcinol, etc.
• formaldehydes e.g., an alkylphenol resin and xyleneformaldehyde resin, etc.
• hydrocarbon tackifying resin examples include, for example: aliphatic hydrocarbon resins [polymers of aliphatic hydrocarbons, such as C 4-5 olefins and dienes (olefins such as butene-1, isobutylene, and pentene-1; and dienes such as butadiene, 1,3-pentadiene, and isoprene)]; hydrocarbon resins [alicyclic hydrocarbon resins obtained by subjecting a so-called “C 4 petroleum fraction” or “C 5 petroleum fraction” to cyclization/dimerization followed by being subjected to polymerization; polymers of cyclic diene compounds (cyclopentadiene, dicyclopentadiene, ethylidene norbornene, and dipentene, etc.) or hydrogenated compounds thereof; and alicyclic hydrocarbon resins obtained by hydrogenating the aromatic ring of the following aromatic hydrocarbon resins and aliphatic and aromatic petroleum resin
• PENSEL D-125 Commercially available products of the polymerized rosin ester that can be preferably used are exemplified by the products with the names of “PENSEL D-125”, “PENSEL D-135”, “PENSEL D-160”, “PENSEL KK”, and “PENSEL C”, etc., which are all made by ARAKAWA CHEMICAL INDUSTRIES, LTD., but are not limited thereto.
• the pressure-sensitive adhesive layer can be a layer in which a pressure-sensitive adhesive composition has been cured. That is, the pressure-sensitive adhesive layer can be formed by providing the pressure-sensitive adhesive composition to an appropriate supporting body (e.g., application, coating) and then by appropriately subjecting it to a curing treatment. When two or more types of curing treatments (drying, cross-link formation, polymerization, etc.) are performed, these treatments can be performed simultaneously or in multiple stages. In the case of the pressure-sensitive adhesive composition using a partial polymer (acrylic polymer syrup), a final copolymerization reaction is typically performed as the curing treatment (the partial polymer is subjected to a further copolymerization reaction to form a complete polymer).
• a partial polymer acrylic polymer syrup
• a photo-curing pressure-sensitive adhesive composition For example, in the case of a photo-curing pressure-sensitive adhesive composition, light irradiation is performed. A curing treatment, such as cross-link formation, drying, or the like, may be performed, if necessary. For example, when a photo-curing pressure-sensitive adhesive composition needs to be dried, photo-curing may be performed after the drying of the composition. In the case of a pressure-sensitive adhesive composition using a complete polymer, a treatment, such as drying (drying by heating), cross-link formation, or the like, is typically performed as the curing treatment, if necessary.
• the application/coating of the pressure-sensitive adhesive composition can be performed by using a commonly-used coater, such as, for example, a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, or the like.
• a commonly-used coater such as, for example, a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, or the like.
• the pressure-sensitive adhesive layer may be formed by directly providing the pressure-sensitive adhesive composition to a supporting body, or the pressure-sensitive adhesive layer formed on a release liner may be transferred to a supporting body.
• the ratio of a solvent-insoluble component in the pressure-sensitive adhesive layer is within a range of 55.0% by mass to 99.0% by mass, and preferably within a range of 60.0% by mass to 95.0% by mass. If the ratio of a solvent-insoluble component is less than 55.0% by mass, cohesive force becomes insufficient, and hence adhesion reliability may be inferior; conversely if the ratio thereof is more than 99.0% by mass, cohesive force becomes too large, and hence an increase in pressure-sensitive adhesive force occurring over time may be insufficient. A method of evaluating the ratio of a solvent-insoluble component will be described later.
• the thickness of the pressure-sensitive adhesive layer is not particularly limited, but is usually within a range of 3 ⁇ m to 200 ⁇ m, and preferably within a range of 5 ⁇ m to 150 ⁇ m. By setting the thickness to be within such a range, good adhesiveness can be achieved. If the thickness thereof is smaller than 3 ⁇ m, an increase in pressure-sensitive adhesive force occurring over time may be inferior; conversely if the thickness thereof is larger than 200 ⁇ m, the effect of suppressing the pressure-sensitive adhesive force, occurring immediately after attachment, may be insufficient.
• the pressure-sensitive adhesive sheet according to the present embodiment comprises a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition.
• a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition.
• such a pressure-sensitive adhesive layer is provided on at least one surface of a supporting body in a fixed manner, i.e., without an intention of separating the pressure-sensitive adhesive layer from the supporting body.
• the concept of the pressure-sensitive adhesive sheet described herein can involve objects referred to as a pressure-sensitive adhesive tape, a pressure-sensitive adhesive film, and a pressure-sensitive adhesive label, etc.
• the pressure-sensitive adhesive sheet may be one cut or punched into an appropriate shape in accordance with its purpose of use.
• the pressure-sensitive adhesive layer is not limited to one continuously formed, but may be one formed into a regular pattern, such as, for example, a dot shape and a stripe shape, or formed into a random pattern.
• the aforementioned supporting body can be formed of a material appropriately selected, in accordance with the application of the pressure-sensitive adhesive tape, from the group consisting of, for example: plastic films, such as polyolefin films including polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene propylene copolymer, ethylene 1-butene copolymer, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, and ethylene vinyl alcohol copolymer, polyester films including polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, polyacrylate film, polystyrene film, polyamide films including nylon 6, nylon 6,6, and partially aromatic polyamide, polyvinylchloride film, polyvinylidene chloride film, and polycarbonate film; foam substrates, such as a polyurethane foam, and polyethylene foam; paper, such as craft paper, crepe paper, and Japanese paper; cloth, such
• the supporting body can also be subjected to, if necessary: a mold-release and antifouling treatment using a release agent, such as a silicone release agent, fluorine release agent, long-chain alkyl release agent, or fatty acid amide release agent, and a silica powder; and an easy-adhesion treatment, such as an acid treatment, alkali treatment, primer treatment, corona treatment, plasma treatment, ultraviolet treatment, or the like.
• the thickness of the supporting body can be appropriately selected in accordance with its purpose, but is generally within a range of approximately 5 ⁇ m to 200 ⁇ m (typically within a range of 10 ⁇ m to 100 ⁇ m).
• the supporting body can also be subjected to, if necessary: a mold-release and antifouling treatment using a release agent, such as a silicone release agent, fluorine release agent, long-chain alkyl release agent, or fatty acid amide release agent, and a silica powder; an easy-adhesion treatment, such as an acid treatment, alkali treatment, primer treatment, corona treatment, plasma treatment, ultraviolet treatment, or the like; and an antistatic treatment, such as a coating type, kneading type, vapor deposition type, or the like.
• a release agent such as a silicone release agent, fluorine release agent, long-chain alkyl release agent, or fatty acid amide release agent, and a silica powder
• an easy-adhesion treatment such as an acid treatment, alkali treatment, primer treatment, corona treatment, plasma treatment, ultraviolet treatment, or the like
• an antistatic treatment such as a coating type, kneading type, vapor deposition type, or
• a release liner can be attached, if necessary, to the surface of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet of the present embodiment.
• Paper or a plastic film can be used as a material for forming the release liner, but a plastic film is preferably used because it is excellent in surface smoothness.
• the film is not particularly limited, as far as it can protect the pressure-sensitive adhesive layer.
• the film include, for example, a polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinylchloride film, vinylchloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, and ethylene-vinylacetate copolymer film, etc.
• the thickness of the release liner is usually within a range of 5 ⁇ m to 200 ⁇ m, and preferably within a range of approximately 10 ⁇ m to 100 ⁇ m. When the thickness is within the aforementioned range, the release liner is excellent in the workability for attaching to the pressure-sensitive adhesive layer and the workability for releasing therefrom, and hence the release liner is preferred.
• the release liner can also be subjected to, if necessary: a mold-release and antifouling treatment using a release agent, such as a silicone release agent, fluorine release agent, long-chain alkyl release agent, or fatty acid amide release agent, and a silica powder; and an antistatic treatment, such as an coating type, kneading type, vapor deposition type, or the like.
• a release agent such as a silicone release agent, fluorine release agent, long-chain alkyl release agent, or fatty acid amide release agent, and a silica powder
• an antistatic treatment such as an coating type, kneading type, vapor deposition type, or the like.
• the pressure-sensitive adhesive sheet has the characteristics that: the pressure-sensitive adhesive force thereof is small immediately after being attached to an adherend, and hence rework can be performed; the pressure-sensitive adhesive force is increased over time; and the adhesion reliability is high.
• the pressure-sensitive adhesive force, occurring immediately after the pressure-sensitive adhesive sheet is attached (after 30 minutes at room temperature), can be evaluated by a 180°-peeling pressure-sensitive adhesive force test performed under the conditions in which a tensile speed is 300 mm/min and a peeling angle is 180°.
• the 180°-peeling pressure-sensitive adhesive force test is performed in accordance with the method and conditions described in the later-described Examples.
• the pressure-sensitive adhesive force of the pressure-sensitive adhesive sheet, occurring over time can be evaluated by a 180°-peeling pressure-sensitive adhesive force test performed under the conditions in which a tensile speed is 300 mm/min and a peeling angle is 180°.
• the 180°-peeling pressure-sensitive adhesive force test is performed in accordance with the method and conditions described in the later-described Examples.
• the pressure-sensitive adhesive sheet has a characteristic that contamination occurring when the sheet is peeled (hereinafter, referred to as a contamination property) is little.
• contamination property of the pressure-sensitive adhesive sheet is evaluated in accordance with the method and conditions described in the later-described Examples.
• the pressure-sensitive adhesive sheet of the present embodiment has characteristics that: the pressure-sensitive adhesive force, occurring at the beginning of attachment, is as low as rework can be performed; thereafter the sheet is firmly adhered to an adherend; and further contamination is little when the sheet is peeled. Accordingly, the pressure-sensitive adhesive sheet can be preferably used: in optical applications in which optical films to be used in image display apparatuses, such as a liquid crystal display, plasma display, and organic EL display, are adhered, etc.; and also as materials for joining members in mobile devices and other electrical and electronic equipment, etc., or as materials for joining various members in automobiles and home electronic appliances, etc.
• MMA methyl methacrylates
• BMA butyl methacrylate
• 2-EHMA 2-ethylhexyl methacrylate
• 3 parts by mass of a methacrylate monomer having a functional group equivalent of 4600 g/mol and containing a polyorganosiloxane skeleton product name: X-22-174DX, made by Shin-Etsu Chemical Co., Ltd.
• 0.51 parts by mass of methyl thioglycolate as a chain transfer agent were placed into a 4-neck flask provided with a stirring blade, thermometer, nitrogen gas inlet pipe, cooler, and
• Each of (Meth)acrylic Polymers 2 to 11 was produced in the same way as (Meth)acrylic Polymer 1, except that a monomer composition, the type of a solvent, and the parts by mass of a chain transfer agent were added in the way described in Table 1.
• MMA methyl methacrylate Tg 105° C.
• BMA BUTYL METHACRYLATE Tg 20° C.
• 2EHMA 2-ethylhexyl methacrylate Tg ⁇ 10° C.
• X-22-174ASX methacrylate monomer containing a polyorganosiloxane skeleton and having a functional group equivalent of 900 g/mol, made by Shin-Etsu Chemical Co., Ltd.
• X-22-174DX methacrylate monomer containing a polyorganosiloxane skeleton and having a functional group equivalent of 4600 g/mol, made by Shin-Etsu Chemical Co., Ltd.
• KF-96-100cs silicone oil (linear silicone) having a polydimethylsiloxane structure, kinematic viscosity 100 mm 2 /s (25° C.), made by Shin-Etsu Chemical Co., Ltd.
• KF-96-100,000cs silicone oil (linear silicone) having a polydimethylsiloxane structure, kinematic viscosity 100,000 mm 2 /s (25° C.), made by Shin-Etsu Chemical Co., Ltd. ⁇ Measurement of Molecular Weight>
• the weight average molecular weight of a polymer was measured by using a GPC apparatus (product name: HLG-8220GPC, made by TOSOH CORP.). Measurement conditions were as follows and the molecular weight was determined by standard polystyrene conversion.
• TMPTA trimethylolpropane triacrylate
• a coated layer having a final thickness of 50 ⁇ m was formed by coating the aforementioned pressure-sensitive adhesive composition on one surface of a polyester film having a thickness of 38 ⁇ m (product name: Diafoil MRF, made by Mitsubishi Plastics Inc.), the one surface having been subjected to a release treatment with silicone. Subsequently, the surface of the coated pressure-sensitive adhesive composition was covered with one surface of a polyester film having a thickness of 38 ⁇ m (product name: Diafoil MRE, made by Mitsubishi Plastics Inc.), the one surface having been subjected to a release treatment with silicone, so that the one surface of the film was located near to the coated layer. Thereby, oxygen was blocked from the coated layer of the pressure-sensitive adhesive composition (pressure-sensitive adhesive composition layer).
• a pressure-sensitive adhesive layer sheet was obtained by irradiating, for 360 seconds, the coated layer thus obtained with ultraviolet rays having an illuminance of 5 mW/cm 2 (measured by TOPCONUVR-T1 having a maximum sensitivity at approximately 350 nm) with the use of a chemical light lamp (made by TOSHIBA CORPORATION) in order to polymerize the composition.
• the polyester films provided on both the surfaces of the pressure-sensitive adhesive layer sheet function as a release liner.
• Each of the pressure-sensitive adhesive layer sheets of Examples 2 to 20 and Comparative Examples 1 to 17 was prepared in the same way as that of Example 1 by preparing a pressure-sensitive adhesive composition in the same way as Example 1, except that the polymer (B) and the use amount thereof listed in Table 2 were used based on 100 parts by mass of the polymer (A) listed in Table 1.
• a pressure-sensitive adhesive composition (1) was prepared: by adding, to 500 parts by mass of a solution (100 parts by mass of the acrylic polymer (A)) in which the aforementioned acrylic polymer (A) solution (35% by mass) was diluted with ethyl acetate to 20% by mass, 3 parts by mass of the (meth)acrylic polymer 2, 1 part by mass of CORONATE L (an adduct of trimethylolpropane/tolylene diisocyanate trimer, made by NIPPON POLYURETHANE INDUSTRY CO., LTD.) as a cross-linking agent, and 3 parts by mass of an ethyl acetate solution (1% by mass) of dioctyl tin dilaurate as a cross-linking catalyst; and then by mixing and stirring them at 25° C. for approximately 5 minutes.
• a pressure-sensitive adhesive layer having a thickness of 50 ⁇ m was formed: by coating the aforementioned pressure-sensitive adhesive composition (1) on one surface of a polyester film having a thickness of 38 ⁇ m (product name: Diafoil MRF, made by Mitsubishi Plastics Inc.), the one surface having been subjected to a release treatment with silicone; and then by heating the composition (1) at 130° C. for approximately 2 minutes.
• Example 21 Each of the pressure-sensitive adhesive layer sheets of Examples 22, 23, 29 to 32 and Comparative Example 18 was prepared in the same way as that of Example 21 by preparing a pressure-sensitive adhesive composition in the same way as Example 21, except that the polymer (B) and the use amount thereof listed in Table 3 were used based on 100 parts by mass of the polymer (A) listed in Table 1.
• Example 29 20 parts by mass of a tackifying resin with the product name of “SUMILITE RESIN PR-12603N” (made by SUMITOMO BAKELITE CO., LTD.) were used.
• Example 30 20 parts by mass of a tackifying resin with the product name of “PENSEL D-125” (made by ARAKAWA CHEMICAL INDUSTRIES, LTD.) were used.
• Example 31 20 parts by mass of a tackifying resin with the product name of “TAMANOL 803L” (made by ARAKAWA CHEMICAL INDUSTRIES, LTD.) were used.
• Example 32 20 parts by mass of a tackifying resin with the product name of “YS Polystar N125” (made by YASUHARA CHEMICAL CO., LTD.) were used.
• the pressure-sensitive adhesive composition (1) was prepared by using the acrylic polymer 2 in the same way as the aforementioned Example 21, and then a pressure-sensitive adhesive sheet was produced.
• the pressure-sensitive adhesive surface of the sheet was attached to the stainless plate (430BA plate), the ABS plate, and a glass plate, respectively, by reciprocating a 2-kg roller.
• PROPERTY OVER TIME EXAMPLE 21 0.17 8.2 0.41 9.9 0.80 7.5 ⁇ ⁇ EXAMPLE 22 0.12 8.2 0.13 10.0 0.28 7.2 ⁇ ⁇ EXAMPLE 23 0.14 5.1 0.28 7.9 0.37 5.7 ⁇ ⁇ EXAMPLE 24 0.89 7.6 0.98 9.9 2.50 9.2 ⁇ ⁇ EXAMPLE 25 0.72 8.2 0.76 10.1 4.80 10.6 ⁇ ⁇ EXAMPLE 26 0.12 5.5 0.14 7.0 0.32 5.8 ⁇ ⁇ EXAMPLE 27 0.84 8.6 1.52 10.1 4.30 10.4 ⁇ ⁇ EXAMPLE 28 0.26 7.9 0.23 9.4 2.40 4.9 ⁇ ⁇ EXAMPLE 29 0.16 2.6 0.15 4.9 0.30 5.3 ⁇ ⁇ EXAMPLE 30 0.35 5.0 2.90 8.2 1.40 5.0 ⁇ ⁇ EXAMPLE 31 0.14 4.6 1.35 7.2 0.20 5.5 ⁇ ⁇ EXAMPLE 32 0.38 4.5 1.80 6.6 0.45
• the present invention can be used, for example, in metal adherends and adherends on which a metal film is formed.

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