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
  • C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
  • C09J4/06—Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09J159/00 - C09J187/00
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/10—Adhesives in the form of films or foils without carriers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
  • C09J7/38—Pressure-sensitive adhesives [PSA]
  • C09J7/381—Pressure-sensitive adhesives [PSA] based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
  • C09J7/387—Block-copolymers
• • 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
  • C08F220/26—Esters containing oxygen in addition to the carboxy oxygen
  • C08F220/30—Esters containing oxygen in addition to the carboxy oxygen containing aromatic rings in the alcohol moiety
• • 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
  • C08F220/34—Esters containing nitrogen, e.g. N,N-dimethylaminoethyl (meth)acrylate
  • C08F220/343—Esters containing nitrogen, e.g. N,N-dimethylaminoethyl (meth)acrylate in the form of urethane links
• • 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
  • C08F265/00—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00
  • C08F265/04—Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00 on to polymers of esters
  • C08F265/06—Polymerisation of acrylate or methacrylate esters on to polymers thereof
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
  • C09J133/04—Homopolymers or copolymers of esters
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J153/00—Adhesives based on block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
• • 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
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
• • G—PHYSICS
  • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
  • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
  • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
  • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
• • 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
  • 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
• • 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
  • C09J2301/00—Additional features of adhesives in the form of films or foils
  • C09J2301/40—Additional features of adhesives in the form of films or foils characterized by the presence of essential components
• • 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
  • C09J2301/40—Additional features of adhesives in the form of films or foils characterized by the presence of essential components
  • C09J2301/416—Additional features of adhesives in the form of films or foils characterized by the presence of essential components use of irradiation
• • 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
  • C09J2453/00—Presence of block copolymer

Definitions

• the present invention relates to a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive sheet with a release film, a pressure-sensitive adhesive sheet for a component of a flexible image display device, a laminate for an image display device, a flexible image display device, a photocurable pressure-sensitive adhesive sheet, and a pressure-sensitive adhesive composition.
• image display devices including curved portions using organic light-emitting diodes (OLEDs) or quantum dots (QDs) and flexible image display devices that can be bent or rolled up have been developed and are becoming widely commercialized.
• OLEDs organic light-emitting diodes
• QDs quantum dots
• a plurality of sheet components such as a cover lens, a circular polarizing plate, a touch film sensor, a color filter, and a light-emitting element are bonded together with a transparent adhesive sheet to form a laminated structure, and when focusing on a certain adhesive sheet, the display device can be regarded as a laminate in which the components and the adhesive sheet are laminated together.
• Patent Document 1 discloses an adhesive and adhesive sheet that can be applied to a repeatedly flexed device by setting the product of the creep compliance variation value and the relaxation elastic modulus variation value in a suitable range for a foldable flexible image display device, as well as a flexed laminate member and a repeatedly flexed device.
• Patent Document 2 discloses a pressure-sensitive adhesive that can be hot-melted and can form a pressure-sensitive adhesive layer with excellent holding power and adhesive power, which contains a (meth)acrylic polymer having a weight-average molecular weight of 50,000 to 1,000,000 obtained by polymerizing a monomer mixture containing a macromonomer and a vinyl monomer having a number-average molecular weight of 500 or more and less than 6,000.
• An object of the present invention is to provide an adhesive sheet having high sensitivity to active energy rays and excellent flexibility and shape stability, and an adhesive sheet with a release film using said adhesive sheet, an adhesive sheet for use as a component of a flexible image display device, a laminate for an image display device, a flexible image display device, a photocurable adhesive sheet, and an adhesive composition.
• the (meth)acrylic copolymer (A) has a structural unit derived from a monomer M that generates an active species that is excited by irradiation with active energy rays, and the pressure-sensitive adhesive sheet satisfies the following requirements (1) and (2).
• the storage shear modulus (G'(-20°C)) at -20°C obtained by dynamic viscoelasticity measurement in a shear mode at a frequency of 1 Hz is 10 kPa or more and 1000 kPa or less; and Requirement (2) The maximum strain value ( ⁇ max ) when a stress of 2 kPa is applied at 60° C. for 600 seconds is less than 80%.
• the pressure-sensitive adhesive sheet according to [1] which has a storage shear modulus at 30° C. (G′(30° C.)) of 1000 kPa or less, as determined by dynamic viscoelasticity measurement in a shear mode at a frequency of 1 Hz.
• a laminate for an image display device in which two components of an image display device are laminated via the pressure-sensitive adhesive sheet according to any one of [1] to [17], and at least one of the components of the image display device has a step having a height difference of 2 ⁇ m or more on a contact surface with the pressure-sensitive adhesive sheet.
• a flexible image display device comprising the laminate for an image display device according to [20].
• the photocurable adhesive sheet has a shear storage modulus (G'(-20°C ) ) at -20°C of 10 kPa or more and 1000 kPa or less, as measured by dynamic viscoelasticity measurement in a shear mode at a frequency of 1 Hz when irradiated with active energy rays having a wavelength of 365 nm at an irradiation dose within a range of 1000 to 5000 mJ/cm2 in an integrated light amount; and Requirement (2') When the photocurable adhesive sheet is irradiated with
• the (meth)acrylic copolymer (A) has a constituent unit derived from a monomer M that generates an active species that is excited by irradiation with active energy rays
• the present invention can provide an adhesive sheet that is highly sensitive to active energy rays and can be cured with high efficiency, and an adhesive sheet with a release film that uses the adhesive sheet, an adhesive sheet for a component of a flexible image display device, a laminate for an image display device, a flexible image display device, a photocurable adhesive sheet, and an adhesive composition.
• (Meth)acrylate is a general term for acrylate and methacrylate. The same applies to "(meth)acryloyl group", “(meth)acrylic acid”, “(meth)acrylonitrile” and “(meth)acrylamide”.
• (meth)acrylic copolymer refers to a copolymer having a structural unit derived from a (meth)acrylic monomer. The (meth)acrylic copolymer may further have a structural unit derived from a monomer other than the (meth)acrylic monomer (e.g., styrene, etc.).
• (meth)acrylic monomer refers to a monomer having a (meth)acryloyl group.
• Vinyl monomer means a compound having an ethylenically unsaturated bond (a polymerizable carbon-carbon double bond).
• a "graft copolymer” is a polymer having one or more types of blocks connected as a side chain polymer structure to a main chain polymer structure. The structures of the main chain polymer and the side chain polymer may be different or the same.
• the method for producing the graft copolymer includes a method in which a macromonomer having a radically polymerizable double bond at the end is produced as a side chain polymer structure, and then radically polymerized with a monomer that will be a constituent unit of the main chain polymer; a method in which a main chain polymer having a reactive site and a macromonomer having a reactive site are produced in advance and then reacted with each other; and a method in which after the production of the main chain polymer, a radical is generated on the main chain polymer using an initiator having a hydrogen abstracting ability, and then a monomer that will be a constituent unit of the side chain polymer is reacted to produce a side chain polymer structure.
• An embodiment of the present invention relates to a pressure-sensitive adhesive sheet.
• the pressure-sensitive adhesive sheet according to the embodiment is a pressure-sensitive adhesive sheet formed from a pressure-sensitive adhesive composition containing a (meth)acrylic copolymer (A).
• the (meth)acrylic copolymer (A) contains a constituent unit derived from a monomer M that is excited by irradiation with active energy rays to generate active species. Therefore, when the (meth)acrylic copolymer (A) is irradiated with active energy rays, the constituent unit derived from the monomer M is excited to generate active species, which act as a photoinitiator.
• the adhesive composition in this embodiment has excellent sensitivity to active energy rays, is easily cured by irradiation with active energy rays, and can give an adhesive sheet with excellent shape stability and restorability, in which the sheet quickly recovers to a flat state when folded.
• the curing reaction proceeds sufficiently without the addition of a separate photoinitiator or by the addition of a very small amount of photoinitiator, bleeding out of the photoinitiator and a decrease in cohesive strength caused by the photoinitiator can be suppressed.
• the (meth)acrylic copolymer (A) contains a structural unit derived from a monomer M (hereinafter also referred to as a "monomer M unit").
• the monomer M is excited by irradiation with active energy rays to generate active species.
• the monomer M can also be said to be a monomer having a structure that is excited by irradiation with active energy rays to generate active species.
• the monomer M typically has a structure that generates active species when excited by irradiation with active energy rays, and a radically polymerizable functional group.
• the radically polymerizable functional group include functional groups having an ethylenically unsaturated bond, such as a (meth)acryloyl group and a vinyl group.
• Examples of active species include radicals, cations, and anions, with radicals being preferred from the standpoint of reactivity.
• structures derived from known photoradical generators can be used, and examples thereof include structures that generate radicals by cleaving and decomposing their own single bonds when excited by irradiation with active energy rays, such as an acylphosphine oxide structure, an ⁇ -aminoacetophenone structure, an ⁇ -hydroxyacetophenone structure, a benzyl ketal structure, etc.; structures that generate radicals by abstracting hydrogen from a hydrogen donor in the pressure-sensitive adhesive composition when excited by irradiation with active energy rays, such as a benzophenone structure, a thioxanthone structure, an anthraquinone structure, a phenylglyoxylate structure, etc.; and an oxi
• Examples of the hydrogen donor in the pressure-sensitive adhesive composition include functional groups contained in the structural units constituting the (meth)acrylic copolymer (A) that have hydrogen directly attached to carbon, such as alkyl groups, and organic functional groups having hydroxyl groups, amino groups, and ether bonds, which are generally used as hydrogen donor groups.
• functional groups having hydroxyl groups, amino groups, and ether bonds are preferred in terms of their ease of donating hydrogen.
• ether bonds tend to easily extract hydrogen from the hydrocarbon structure adjacent to the ether bond, and it is preferable that the hydrogen donor group containing an ether bond has such a structure having hydrogen.
• a compound having the above functional group may be added separately as a hydrogen donor.
• the radical generating group is preferably a structure that generates radicals by abstracting hydrogen from a hydrogen donor in the adhesive composition when excited by irradiation with active energy rays, and among these, from the viewpoint of suppressing coloration, a benzophenone structure or a phenyl glyoxylate structure is preferred, with a benzophenone structure being particularly preferred.
• the radical generating group preferably has a structure that generates radicals by cleaving its own single bond when excited by irradiation with active energy rays, and among these, from the viewpoint of suppressing coloration, an ⁇ -hydroxyacetophenone structure or a benzyl ketal structure is preferred, with an ⁇ -hydroxyacetophenone structure being particularly preferred.
• the monomer M is preferably a monomer represented by the following formula (I):
• R1 represents a hydrogen atom, a methyl group, or an ethyl group.
• a hydrogen atom or a methyl group is preferred, and a methyl group is particularly preferred.
• R2 represents a linear or branched alkylene group having 1 to 5 carbon atoms.
• R2 represents a linear or branched alkylene group having 1 to 5 carbon atoms.
• an ethylene group a propane-1,3-diyl group, a butane-1,3-diyl group, and a butane-1,4-diyl group are preferred, and an ethylene group is more preferred.
• R 3 and R 4 each independently represent a linear or branched alkyl group having 1 to 5 carbon atoms.
• R3 and R4 may be bonded to each other to form a ring.
• the ring formed by R3 and R4 preferably has 5 to 8 carbon atoms, more preferably 6 carbon atoms.
• R3 and R4 are each independently a methyl group or an ethyl group, or that R3 and R4 are bonded to each other to form a cyclohexane ring together with the carbon atom to which R3 and R4 are bonded, it is more preferable that at least one of R3 and R4 is a methyl group, and it is even more preferable that both R3 and R4 are methyl groups.
• monomer represented by formula (I) examples include 2-[4-(2-hydroxy-2-methyl-1-oxopropyl)phenoxy]ethyl methacrylate, 2-[4-(2-hydroxy-2-methyl-1-oxopropyl)phenoxy]ethyl acrylate, and the like.
• the content of the monomer M unit in the (meth)acrylic copolymer (A) is preferably 0.01 to 20% by mass, more preferably 0.03 to 10% by mass, even more preferably 0.05 to 5% by mass, particularly preferably 0.08 to 3% by mass, and most preferably 0.1 to 2% by mass, based on 100% by mass of all the constituent units constituting the (meth)acrylic copolymer (A).
• the content of the monomer M unit is equal to or greater than the lower limit, the sensitivity to active energy rays and shape stability are superior, and when it is equal to or less than the upper limit, the compatibility with other components is superior.
• the (meth)acrylic copolymer (A) preferably contains, in addition to the monomer M units, a structural unit derived from an alkyl (meth)acrylate (a1) having an alkyl group of 4 to 30 carbon atoms (hereinafter also referred to as an "(a1) unit").
• a structural unit derived from any one or more copolymerizable monomers selected from the group consisting of a carboxy group-containing monomer (a2), a hydroxy group-containing monomer (a3), a nitrogen-containing monomer (a4), an epoxy group-containing monomer (a5), a vinyl monomer (a6), an alkyl (meth)acrylate monomer (a7) having an alkyl group of 1 to 3 carbon atoms, an alicyclic monomer (a8), a macromonomer (a9), and other copolymerizable monomers (a10).
• a structural unit derived from any one or more copolymerizable monomers selected from the group consisting of a carboxy group-containing monomer (a2), a hydroxy group-containing monomer (a3), a nitrogen-containing monomer (a4), an epoxy group-containing monomer (a5), a vinyl monomer (a6), an alkyl (meth)acrylate monomer (a7) having an alkyl group
• the composition does not contain a carboxyl group-containing monomer (a2) and contains at least one selected from the group consisting of a hydroxyl group-containing monomer (a3) and a nitrogen-containing monomer (a4).
• a carboxyl group-containing monomer (a2) By not containing a carboxyl group-containing monomer (a2) and containing at least one selected from the group consisting of a hydroxyl group-containing monomer (a3) and a nitrogen-containing monomer (a4), it is possible to provide both corrosion resistance, adhesion, and resistance to wet heat whitening when the adherend contains a corrosive component such as a metal. Furthermore, among these, those containing at least one of the hydroxyl group-containing monomer (a3) and the nitrogen-containing monomer (a4) are preferred in that the hydroxyl group-containing monomer (a3) and the nitrogen-containing monomer (a4) form a non-covalent bond such as a hydrogen bond, thereby enhancing the cohesive strength.
• the alkyl (meth)acrylate (a1) is a linear or branched alkyl (meth)acrylate having an alkyl group of 4 to 30 carbon atoms, and is represented by the following formula (II).
• CH2 CR5 - COOR6 (II) (In the formula, R5 represents a hydrogen atom or a methyl group, and R6 represents a linear or branched alkyl group having 4 to 30 carbon atoms.)
• the alkyl (meth)acrylate represented by formula (II) may, for example, be straight-chain alkyl (meth)acrylates such as n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, icosyl (meth)acrylate, henicosyl (meth)acrylate, and behenyl (meth)acrylate; sec-butyl (meth)acrylate
• branched alkyl (meth)acrylates examples include butyl (meth)acrylate, t-butyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, isostearyl (meth)acrylate, isoicosyl (meth)acrylate, butyloctyl (meth)acrylate, isomyristyl (meth)acrylate, isocetyl (meth)acrylate, hexyldecyl (meth)acrylate, isostearyl (meth)acrylate, octyldecyl (meth)acrylate, octyldodecyl (meth)acrylate, and isobehenyl (me
• linear or branched alkyl (meth)acrylates in which the alkyl group has 4 to 20 carbon atoms, further 5 to 18, particularly 6 to 16, and especially 7 to 14 carbon atoms are preferred, and for example, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, sec-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate,
• the content of the (a1) unit in the (meth)acrylic copolymer (A) is preferably 5 to 95% by mass, more preferably 10 to 90% by mass, even more preferably 15 to 85% by mass, and particularly preferably 20 to 80% by mass, based on 100% by mass of all the constituent units constituting the (meth)acrylic copolymer (A).
• the content of the (a1) unit is equal to or greater than the lower limit, the flexibility tends to be excellent, and even when the adherend has unevenness, the conformability tends to be excellent.
• the content is equal to or less than the upper limit, the effect of the copolymerizable monomer is easily obtained, and the adhesive strength and cohesive strength tend to be excellent.
• the lower limit and upper limit of the content of the (a1) unit can be arbitrarily combined.
• carboxyl group-containing monomer (a2) examples include (meth)acrylic acid, 2-acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxyethyl maleic acid, 2-(meth)acryloyloxypropyl maleic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, and itaconic acid. These may be used alone or in combination of two or more.
• hydroxyl group-containing monomer (a3) examples include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; caprolactone-modified hydroxy (meth)acrylates such as caprolactone-modified 2-hydroxyethyl (meth)acrylate; oxyalkylene-modified (meth)acrylates such as diethylene glycol (meth)acrylate and polyethylene glycol (meth)acrylate; ) acrylate, 2-acryloyloxyethyl-2-hydroxyethyl phthalate, and other primary hydroxyl group-containing (meth)acrylates; 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, and
• hydroxyl group-containing monomers (a3) hydroxyl group-containing monomers having a hydroxyalkyl group with 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, and especially 2 to 4 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutyl vinyl ether, are preferred, and primary hydroxyl group-containing (meth)acrylates, such as 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate, are particularly preferred.
• the content of the structural units derived from the hydroxyl group-containing monomer (a3) in the (meth)acrylic copolymer (A) is preferably 0.1 to 30% by mass, more preferably 0.5 to 25% by mass, even more preferably 1 to 10% by mass, and particularly preferably 2 to 7% by mass, based on 100% by mass of all structural units constituting the (meth)acrylic copolymer (A), from the viewpoint of imparting adhesive strength and resistance to wet heat whitening.
• the nitrogen-containing monomer (a4) may be, for example, an amino group-containing monomer, an amide group-containing monomer, an isocyanate group-containing monomer, or (meth)acrylonitrile.
• the nitrogen-containing monomer (a4) improves the cohesive strength of the adhesive sheet and can suppress whitening due to moist heat. These may be used alone or in combination of two or more.
• the above amino group-containing monomers include, for example, primary amino group-containing (meth)acrylates such as aminomethyl (meth)acrylate and aminoethyl (meth)acrylate; secondary amino group-containing (meth)acrylates such as t-butylaminoethyl (meth)acrylate and t-butylaminopropyl (meth)acrylate; tertiary amino group-containing (meth)acrylates such as ethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, diethylaminopropyl (meth)acrylate, and dimethylaminopropylacrylamide; N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine
• the above-mentioned amide group-containing monomers include, for example, (meth)acrylamide; N-alkyl (meth)acrylamides such as N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-propyl (meth)acrylamide, N-n-butyl (meth)acrylamide, diacetone (meth)acrylamide, and N,N'-methylene bis (meth)acrylamide; N,N-dialkyl (meth)acrylamides such as N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N,N-dipropyl (meth)acrylamide, N,N-ethylmethyl acrylamide, and N,N-diallyl (meth)acrylamide; hydroxyalkyl (meth)acrylamides such as N-hydroxymethyl (meth)acrylamide and N-hydroxyethyl (meth)acrylamide; alkoxyalkyl (meth)acryl
• Examples of the isocyanate group-containing monomer include 2-(meth)acryloyloxyethyl isocyanate and its alkylene oxide adducts.
• the isocyanate group may be protected with a blocking agent such as methyl ethyl ketone oxime, 3,5-dimethylpyrazole, 1,2,4-triazole, or diethyl malonate.
• those having a tertiary nitrogen atom are preferred because they have a sensitizing effect on the hydrogen abstraction reaction described below, and as a result, crosslinks can be formed efficiently.
• tertiary amino group-containing (meth)acrylates, N,N-dialkyl (meth)acrylamides, N-vinylpyrrolidone, acryloylmorpholine, etc. are particularly preferred.
• the content of the constituent units derived from the nitrogen-containing monomer (a4) in the (meth)acrylic copolymer (A) is preferably 0.1 to 15% by mass, more preferably 0.5 to 13% by mass, even more preferably 1 to 10% by mass, and particularly preferably 2 to 7% by mass, based on 100% by mass of all the constituent units constituting the (meth)acrylic copolymer (A), from the viewpoint of imparting cohesive strength and resistance to wet heat whitening.
• Examples of the epoxy group-containing monomer (a5) include glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate glycidyl ether. These may be used alone or in combination of two or more.
• the vinyl monomer (a6) may be a compound having a vinyl group in the molecule.
• examples of such compounds include vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl laurate, and vinyl stearate, as well as aromatic vinyl monomers such as styrene, chlorostyrene, chloromethylstyrene, ⁇ -methylstyrene, and other substituted styrenes. These may be used alone or in combination of two or more.
• alkyl (meth)acrylate monomer (a7) in which the alkyl group has 1 to 3 carbon atoms examples include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, etc. These may be used alone or in combination of two or more.
• the content of the constituent units derived from the alkyl (meth)acrylate monomer (a7) in the (meth)acrylic copolymer (A) is preferably 0.1 to 15 mass%, more preferably 0.5 to 13 mass%, even more preferably 1 to 10 mass%, and particularly preferably 2 to 7 mass%, relative to 100 mass% of all constituent units constituting the (meth)acrylic copolymer (A), from the viewpoint of imparting cohesive strength to the adhesive sheet.
• Examples of the alicyclic monomer (a8) include cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, adamantyl (meth)acrylate, etc. These may be used alone or in combination of two or more.
• the content of the constituent units derived from the alicyclic monomer (a8) in the (meth)acrylic copolymer (A) is preferably 0.1 to 15 mass%, more preferably 0.5 to 13 mass%, even more preferably 1 to 10 mass%, and particularly preferably 2 to 7 mass%, relative to 100 mass% of all constituent units constituting the (meth)acrylic copolymer (A), from the viewpoint of imparting cohesive strength to the adhesive sheet.
• the macromonomer (a9) is a monomer that can easily increase the number of carbon atoms in the side chain, for example, 20 or more, when it becomes the (meth)acrylic copolymer (A) by polymerization.
• the (meth)acrylic copolymer can be made into a graft copolymer having a segment containing a structural unit derived from the macromonomer (a9).
• the cohesive force of the (meth)acrylic copolymer (A) is improved, which is preferable in that the cohesive force of the pressure-sensitive adhesive sheet can be easily increased.
• the properties of the main chain and side chains of the graft copolymer can be changed by selecting the macromonomer (a9) and other monomers and by adjusting the blending ratio.
• the total content of the monomer M units and the (a1) to (a9) units does not exceed 100% by mass.
• the macromonomer (a9) preferably has a skeleton component composed of an acrylic copolymer or a vinyl polymer.
• the skeleton component of the macromonomer include the monomer M, the alkyl(meth)acrylate (a1) having 4 to 30 carbon atoms in the alkyl group, the vinyl monomer (a6), the alkyl(meth)acrylate monomer (a7) having 1 to 3 carbon atoms in the alkyl group, and the alicyclic monomer (a8).
• alkyl (meth)acrylates having an alkyl group with 1 to 8 carbon atoms, alicyclic monomers, and aromatic monomers such as styrene, since this allows the production of a pressure-sensitive adhesive sheet with excellent cohesive strength.
• alkyl (meth)acrylate having 9 to 30 carbon atoms, since this allows the production of a pressure-sensitive adhesive sheet that has an appropriate cohesive strength and excellent flexibility.
• the macromonomer has a radical polymerizable functional group or a functional group such as a hydroxyl group, an isocyanate group, an epoxy group, a carboxyl group, an amino group, an amide group, or a thiol group.
• a radical polymerizable functional group copolymerizable with other monomers is preferable.
• the macromonomer may have one or more radical polymerizable functional groups, and among them, one having one is particularly preferable.
• the functional group may also have one or more functional groups, and among them, one having one is particularly preferable.
• the compound may contain either a radically polymerizable functional group or a functional group, or may contain both.
• the weight average molecular weight of the macromonomer (a9) is preferably from 1,000 to 40,000, more preferably from 1,500 to 20,000, and even more preferably from 2,000 to 15,000.
• the weight average molecular weight of the macromonomer (a9) is a value calculated in terms of standard polystyrene as measured by gel permeation chromatography (GPC).
• the macromonomer (a9) may be one produced by a known method, or a commercially available one (e.g., a macromonomer manufactured by Toagosei Co., Ltd.) may be used.
• the content of the structural unit derived from the macromonomer (a9) in the (meth)acrylic copolymer (A) is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, and even more preferably 5 to 15% by mass, based on 100% by mass of all structural units constituting the (meth)acrylic copolymer (A). If it is equal to or greater than the lower limit, the phase separation force between the segment containing the structural unit derived from the macromonomer (a9) and the segment formed by the other structural units becomes stronger, and the pressure-sensitive adhesive sheet tends to have better shape retention when not laminated. If it is equal to or less than the upper limit, the pressure-sensitive adhesive sheet tends to have better unevenness-following ability when laminated.
• the lower and upper limits of the content can be combined in any combination.
• copolymerizable monomers (a10) include (meth)acrylates having an alkoxyalkylene glycol skeleton such as methoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, butoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, butoxypolypropylene glycol (meth)acrylate, methoxypolytetramethylene glycol (meth)acrylate, butoxypolytetramethylene glycol (meth)acrylate, methoxypolyoxyethylene polyoxypropylene glycol (meth)acrylate, and butoxypolyoxyethylene polyoxypropylene glycol (meth)acrylate, as well as heterocyclic ring-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate. These may be used alone or in combination of two or more.
• the weight average molecular weight (Mw) of the (meth)acrylic copolymer (A) is preferably 50,000 to 2,000,000, more preferably 100,000 to 1,500,000, and even more preferably 300,000 to 1,000,000. If the weight average molecular weight of the (meth)acrylic copolymer (A) is equal to or greater than the lower limit, the durability of the adhesive sheet after lamination tends to be good. If the weight average molecular weight of the (meth)acrylic copolymer (A) is equal to or less than the upper limit, the moldability during the production of the adhesive sheet tends to be good. The lower limit and upper limit of the weight average molecular weight can be combined arbitrarily. The weight average molecular weight of the (meth)acrylic copolymer (A) is a value calculated in terms of standard polystyrene as measured by gel permeation chromatography (GPC).
• the melt viscosity of the (meth)acrylic copolymer (A) at 130°C is preferably 20 Pa ⁇ s or more and 800 Pa ⁇ s or less, more preferably 50 Pa ⁇ s or more and 600 Pa ⁇ s or less, and even more preferably 100 Pa ⁇ s or more and 500 Pa ⁇ s or less. If the melt viscosity of the (meth)acrylic copolymer (A) at 130°C is within the above range, the adhesive composition containing the (meth)acrylic copolymer (A) can be applied by a hot melt method in which the adhesive composition is heated as it is. The lower limit and the upper limit of the melt viscosity can be combined arbitrarily. The melt viscosity can be measured, for example, using a viscoelasticity measuring device Rheosol-G5000 manufactured by UBM Corporation.
• the method for producing the (meth)acrylic copolymer (A) is not particularly limited, and any known polymerization method can be used.
• the polymerization method may be a known polymerization method such as solution polymerization, suspension polymerization, emulsion polymerization, etc. Since the adhesive sheet is to be used as such, the solution polymerization method is preferred.
• the content of the (meth)acrylic copolymer (A) in the adhesive composition forming the adhesive sheet according to the embodiment is preferably 50 to 99.5 mass%, more preferably 75 to 99 mass%, and even more preferably 90 to 98 mass%, relative to 100 mass% of the adhesive composition.
• the lower and upper limits of the content of the (meth)acrylic copolymer (A) can be arbitrarily combined.
• the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive sheet preferably contains a photocurable compound (B) in addition to the (meth)acrylic copolymer (A).
• a photocurable compound (B) By including the photocurable compound (B), the curing efficiency by active energy rays can be increased, and the cohesive force after curing by active energy rays can be improved, and shape stability and recovery can be improved.
• the copolymer (A) may be polymerized by the action of the monomer M unit in the copolymer (A) or the photoinitiator (C) described later. When a sufficient crosslinked structure can be formed at least either intramolecularly or intermolecularly, it is not necessarily required to contain the photocurable compound (B).
• the photocurable compound (B) is a compound having one or more radically polymerizable groups, preferably a (meth)acryloyl group.
• examples of the photocurable compound (B) include monofunctional (meth)acrylates and polyfunctional (meth)acrylates. Polyfunctional (meth)acrylates are preferred because they can efficiently form a crosslinked structure.
• Examples of the monofunctional (meth)acrylates include monofunctional (meth)acrylate monomers and monofunctional (meth)acrylate oligomers.
• Examples of the polyfunctional (meth)acrylates include polyfunctional (meth)acrylate monomers and polyfunctional (meth)acrylate oligomers. These may be used alone or in combination of two or more.
• polyfunctional (meth)acrylate monomer examples include 1,4-butanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerin glycidyl ether di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecane dimethacrylate, tricyclodecane dimethanol di(meth)acrylate, bisphenol A polyethoxy di(meth)acrylate, bisphenol A poly Polypropoxy di(meth)acrylate, bisphenol F polyethoxy di(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane trioxyethyl (meth)acrylate, ⁇ -caprolactone modified tris(2-
• those having an alkylene glycol skeleton such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and polytetramethylene glycol di(meth)acrylate, are more preferred.
• the molecular weight of the polyfunctional (meth)acrylate monomer is preferably 200 or more, more preferably 300 or more, even more preferably 400 or more, and particularly preferably 500 or more, from the viewpoint of imparting appropriate flexibility to the cured product.
• the upper limit of the molecular weight of the polyfunctional (meth)acrylic monomer is usually 3000 or less, and preferably 2000 or less.
• polyfunctional (meth)acrylic oligomer examples include polyester (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, and polyether (meth)acrylate. Of these, urethane (meth)acrylates are preferred from the viewpoint of imparting appropriate toughness to the cured product.
• the polyfunctional urethane (meth)acrylate can be obtained by reacting a polyol, a polyisocyanate, and a hydroxyl group-containing (meth)acrylate.
• the polyol may be any compound having two or more hydroxyl groups, such as aliphatic polyols, alicyclic polyols, polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, polybutadiene polyols, polyisoprene polyols, (meth)acrylic polyols, polysiloxane polyols, etc.
• polyether polyols are preferred, and polyethylene glycol, polypropylene glycol, and polytetramethylene glycol are particularly preferred.
• the above polyol compounds may be used alone or in combination of two or more.
• the polyisocyanate may be any compound having two or more isocyanate groups, such as aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, triisocyanate, and the like.
• aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate,
• polyisocyanates examples include aliphatic polyisocyanates such as methylhexamethylene diisocyanate, lysine diisocyanate, and lysine triisocyanate; alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and norbornene diisocyanate; trimer compounds or polymer compounds of these polyisocyanates; allophanate-type polyisocyanates; biuret-type polyisocyanates; and water-dispersible polyisocyanates.
• aliphatic polyisocyanates such as methylhexamethylene diisocyanate, lysine diisocyanate, and lysine triisocyanate
• alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diiso
• diisocyanates are preferred from the viewpoint of stability during the urethanization reaction, and in particular, aliphatic diisocyanates such as pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate, and alicyclic diisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 1,3-bis(isocyanatemethyl)cyclohexane are preferably used.
• the above isocyanates can be used alone or in combination of two or more.
• the hydroxyl group-containing (meth)acrylate is a compound having a hydroxyl group and a (meth)acryloyl group.
• the number of hydroxyl groups is preferably 1 to 5, and particularly preferably 1.
• hydroxyl group-containing (meth)acrylates examples include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate, 2-hydroxyethyl acryloyl phosphate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, dipropylene glycol mono(meth)acrylate, fatty acid-modified glycidyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, and dimethylol cyclohexane.
• hydroxyl group-containing (meth)acrylate examples include xyl mono(meth)acrylate and hydroxycaprolactone (meth)acrylate, which contain one (meth)acryloyl group; hydroxyl group-containing (meth)acrylate including glycerin di(meth)acrylate and 2-hydroxy-3-acryloyl-oxypropyl methacrylate, which contain two (meth)acryloyl groups; and hydroxyl group-containing (meth)acrylate including pentaerythritol tri(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, and ethylene oxide-modified dipentaerythritol penta(meth
• hydroxyl-containing (meth)acrylates containing two or less (meth)acryloyl groups are preferred, and among these, compounds containing one (meth)acryloyl group such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, dimethylolcyclohexyl mono(meth)acrylate, and hydroxycaprolactone (meth)acrylate are preferred, and among these, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate are preferred.
• the molecular weight of the polyfunctional (meth)acrylic oligomer is preferably 3,000 or more, more preferably 5,000 or more, even more preferably 8,000 or more, and particularly preferably 10,000 or more.
• the upper limit of such molecular weight is usually 100,000 or less, and preferably 50,000 or less.
• Monofunctional (meth)acrylates are compounds that have one (meth)acryloyl group. By including monofunctional (meth)acrylates, the molecular weight between crosslinking points of the cured product can be increased, which is preferable in that it increases the freedom of movement of the molecular chains and makes it easier to obtain a cured product with excellent stress relaxation properties.
• Examples of monofunctional (meth)acrylate monomers include those listed as monomers that form the (meth)acrylic copolymer (A).
• Examples of monofunctional (meth)acrylate oligomers include polyester (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, polyether (meth)acrylate, etc. Among these, (meth)acrylate oligomers having an alkylene glycol skeleton are preferred from the viewpoint of flexibility.
• the (meth)acrylate oligomer having an alkylene glycol skeleton may, for example, be a monofunctional (meth)acrylate oligomer represented by the following formula (III).
• CH 2 CR 7 -COO-R 8 -Y-(R 9 O) k -R 10 ...(III)
• R7 represents a hydrogen atom or a methyl group.
• R 8 represents an alkenyl group having 1 to 20 carbon atoms, which may have an ether bond or a cyclic structure in the chain.
• Y represents a bonding group selected from a urethane bond, an ester bond, an ether bond, a carbonate bond, an amide bond, and a urea bond. In terms of imparting appropriate toughness to the cured product, Y is preferably a urethane bond, an amide bond, or a urea bond, and more preferably a urethane bond.
• R 9 represents an alkylene group, which is an ethylene group or a propylene group.
• (R 9 O) k can be expressed as [(C 2 H 4 O) r (C 3 H 6 O) s ].
• r is an integer of 0 or 1 or more
• s is an integer of 0 or 1 or more
• r + s k.
• [(C 2 H 4 O) r (C 3 H 6 O) s ] when an oxyethylene structure (C 2 H 4 O) and an oxypropylene structure (C 3 H 6 O) coexist, they may be of a random type or a block type.
• k is an integer of 1 to 500, representing the number of repeating units of (R 9 O), that is, r+s, which is the total number of repeating units of (C 2 H 4 O) r and (C 3 H 6 O) s .
• R 10 represents an alkyl group having 1 to 20 carbon atoms, which may have an ether bond or a cyclic structure in the chain.
• the photocurable compound (B) preferably has a glass transition temperature of -20°C or lower when homopolymerized, i.e., a polymer obtained by polymerizing only the photocurable compound (B), more preferably -25°C or lower, even more preferably -30°C or lower, and particularly preferably -40°C or lower.
• the glass transition temperature of the polymer when homopolymerized is preferably -80°C or higher, more preferably -75°C or higher, even more preferably -70°C or higher, and particularly preferably -65°C or higher.
• the glass transition temperature is preferably -80°C or higher and -20°C or lower, more preferably -75°C or higher and -25°C or lower, even more preferably -70°C or higher and -30°C or lower, and particularly preferably -65°C or higher and -40°C.
• the weight average molecular weight (Mw) of the monofunctional (meth)acrylate oligomer is preferably 30,000 or less, more preferably 28,000 or less, and even more preferably 25,000 or less, from the viewpoint of reducing the storage shear modulus at low temperatures while maintaining high recovery when bent.
• the lower limit is preferably 3,000 or more, more preferably 4,000 or more, and even more preferably 5,000 or more, from the viewpoint of preventing a decrease in adhesion.
• the weight average molecular weight of the monofunctional (meth)acrylate oligomer is preferably 3,000 or more and 30,000 or less, more preferably 4,000 or more and 28,000 or less, and even more preferably 5,000 or more and 25,000 or less.
• the weight average molecular weight of the monofunctional (meth)acrylate oligomer is a value calculated in terms of standard polystyrene as measured by gel permeation chromatography (GPC).
• the content of the photocurable compound (B) in the adhesive composition forming the adhesive sheet is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1.0 parts by mass or more, and particularly preferably 1.2 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic copolymer (A).
• the content of the photocurable compound (B) is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 25 parts by mass or less, particularly preferably 10 parts by mass or less, and most preferably 5 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic copolymer (A).
• the lower limit and upper limit of the content of the photocurable compound (B) can be arbitrarily combined.
• the content of the photocurable compound (B) is preferably 0.1 parts by mass or more and 50 parts by mass or less, more preferably 0.5 parts by mass or more and 30 parts by mass or less, even more preferably 1.0 parts by mass or more and 25 parts by mass or less, particularly preferably 1.2 parts by mass or more and 10 parts by mass or less, and most preferably 1.0 parts by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic copolymer (A).
• the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive sheet may contain a photoinitiator (C) other than the (meth)acrylic copolymer (A) as necessary.
• a photoinitiator (C) is a compound that generates active radical species when irradiated with light such as ultraviolet light or visible light, more specifically, with light having a wavelength of 200 nm to 780 nm.
• the photoinitiator (C) can be appropriately selected from known photoinitiators, and examples thereof include cleavage type photoinitiators and hydrogen abstraction type photoinitiators.
• cleavage-type photoinitiators examples include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-[4- ⁇ 4-(2-hydroxy-2-methyl-propionyl)benzyl ⁇ phenyl]-2-methyl-propan-1-one, oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone), 2-benzyl-2-dimethylamino-1-(4-morpholino-1-methylamino)propanone, and 2-benzyl-2-dimethylamino-1-(4-morpholino-1-methylamino)propanone.
• hydrogen abstraction type photoinitiators examples include benzophenone, 4-methyl-benzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4-(meth)acryloyloxybenzophenone, 2-methylbenzoylbenzoate, 4-[(4-methylphenyl)thio]benzophenone, 4-acryloyloxybenzophenone, 4-acryloyloxyethoxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'-methoxybenzophenone, 4-acryloyloxy-4'-bromobenzophenone, 4-acryloyloxyethoxy- Intermolecular hydrogen abstraction type photoinitiators such as 4'-bromobenzophenone, 4-methacryloyloxybenzophenone, 4-methacryloyloxyethoxybenzophenone, 4-methacryloyloxy
• the cleavage type photoinitiator and the hydrogen abstraction type photoinitiator may be used either alone or in combination. Furthermore, the cleavage type photoinitiator and the hydrogen abstraction type photoinitiator may each be used alone or in combination of two or more.
• the photoinitiator (C) preferably contains a hydrogen abstraction type photoinitiator. When the photoinitiator (C) contains a hydrogen abstraction type photoinitiator, a hydrogen abstraction reaction also occurs from the (meth)acrylic copolymer (A), and a crosslinked structure having many crosslinking points can be formed.
• intramolecular hydrogen abstraction type photoinitiators are preferred in that they can be the starting point for radical generation, not only as hydrogen donors in the system, but also themselves.
• the content of the photoinitiator (C) in the adhesive composition forming the adhesive sheet is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 1 part by mass or more, relative to 100 parts by mass of the (meth)acrylic copolymer (A).
• the content of the photoinitiator (C) is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, and particularly preferably 2 parts by mass or less, relative to 100 parts by mass of the copolymer (A).
• the lower limit and upper limit of the content of the photoinitiator (C) can be arbitrarily combined.
• the content of the photoinitiator (C) is preferably 0.1 parts by mass or more and 10 parts by mass or less, more preferably 0.3 parts by mass or more and 5 parts by mass or less, even more preferably 0.5 parts by mass or more and 3 parts by mass or less, and particularly preferably 1 part by mass or more and 2 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic copolymer (A).
• the adhesive composition forming the adhesive sheet may further contain other components other than the (meth)acrylic copolymer (A), the photocurable compound (B) and the photoinitiator (C) as necessary.
• other components include various additives such as silane coupling agents, tackifier resins, plasticizers, antioxidants, light stabilizers, metal deactivators, antiaging agents, moisture absorbents, polymerization inhibitors, ultraviolet absorbers, rust inhibitors, inorganic particles, sensitizers, and pigments.
• the content of the additives is typically set so as not to adversely affect the curing of the adhesive sheet or to adversely affect the physical properties of the adhesive sheet.
• the method for producing the pressure-sensitive adhesive sheet according to the embodiment is not particularly limited.
• the adhesive sheet according to the embodiment can be obtained by mixing the (meth)acrylic copolymer (A) with the photocurable compound (B), photoinitiator (C), and additives, each in a predetermined amount, to prepare an adhesive composition, forming the adhesive composition into a sheet, crosslinking and curing the composition by a radical reaction, and processing the composition appropriately as necessary.
• the adhesive sheet according to the embodiment can be obtained by preparing the adhesive composition as described above, coating the adhesive composition on a component of an image display device, and curing the adhesive composition.
• Examples of the method for mixing the components include methods using a single screw extruder, a twin screw extruder, a planetary mixer, a twin screw mixer, a pressure kneader, and the like.
• Methods for forming the pressure-sensitive adhesive composition into a sheet include, for example, wet lamination, dry lamination, extrusion casting using a T-die, extrusion lamination, calendaring, inflation, injection molding, and liquid injection curing.
• the adhesive sheet according to the embodiment may be formed by dissolving the adhesive composition in an appropriate solvent, coating it using various coating methods, and irradiating it with active energy rays.
• the adhesive composition can be cured by irradiating it with active energy rays.
• an adhesive sheet according to the embodiment can be produced by irradiating a molded product of the adhesive composition, such as a sheet of the adhesive composition, with active energy rays. Note that in addition to irradiating it with active energy rays, the adhesive composition can also be cured by further heating.
• the crosslinked structure can be formed by activating the photoinitiator and generating radicals in the structural units derived from the monomer M.
• Examples of the active energy rays to be irradiated include ionizing radiation such as ⁇ rays, ⁇ rays, ⁇ rays, neutron rays, and electron beams, ultraviolet rays, and visible light.
• ultraviolet rays are preferred from the viewpoints of suppressing damage to components of the image display device and controlling reactions.
• Examples of light sources for irradiating the active energy rays include high-pressure mercury lamps, metal halide lamps, xenon lamps, halogen lamps, LED lamps, and fluorescent lamps.
• the amount of irradiation of active energy rays is preferably 6000 mJ/cm 2 or less, more preferably 5000 mJ/cm 2 or less, even more preferably 4000 mJ/cm 2 or less, and particularly preferably 3000 mJ/cm 2 or less.
• the amount of irradiation of active energy rays is preferably 100 mJ/cm 2 or more, more preferably 250 mJ/cm 2 or more, even more preferably 500 mJ/cm 2 or more, and particularly preferably 1000 mJ/cm 2 or more.
• the lower limit and upper limit of the amount of irradiation of active energy rays can be arbitrarily combined.
• the pressure-sensitive adhesive sheet according to one embodiment satisfies the following requirement (1).
• the storage modulus (G'(-20°C)) at -20°C obtained by dynamic viscoelasticity measurement in a shear mode at a frequency of 1 Hz is 10 kPa or more and 1,000 kPa or less.
• a PSA sheet satisfying the requirement (1) is soft even at low temperatures and has excellent flexibility. For example, even when repeatedly folded at a low temperature of ⁇ 20° C., the member to which the PSA sheet is adhered is unlikely to crack or break.
• G'(-20°C) of requirement (1) is preferably 30 kPa or more, more preferably 50 kPa or more, and even more preferably 100 kPa or more.
• G'(-20°C) of requirement (1) is preferably 800 kPa or less, more preferably 600 kPa or less, even more preferably 400 kPa or less, and particularly preferably 300 kPa or less.
• the lower limit and upper limit of G'(-20°C) of requirement (1) can be arbitrarily combined. Specifically, it is preferably 30 kPa or more and 800 kPa or less, more preferably 50 kPa or more and 600 kPa or less, even more preferably 100 kPa or more and 400 kPa or less, and particularly preferably 100 kPa or more and 300 kPa or less.
• Requirement (1) is a value measured after adjusting the thickness to the range of 0.7 to 1.0 mm, which allows the storage shear modulus G' to be accurately measured without being influenced by the measuring tool.
• the above-mentioned "thickness of 0.7 to 1.0 mm" means that if the thickness of the PSA sheet as the measurement sample does not fall within this range, the thickness of the measurement sample is adjusted to fall within this range by stacking several sheets, etc. The same applies when the thickness of the measurement sample is specified in other tests.
• the measurement of G'(-20°C) in the requirement (1) is carried out, for example, as follows.
• the pressure-sensitive adhesive sheets are repeatedly laminated to adjust the thickness to 0.7 to 1.0 mm (for example, 0.8 mm), and then a circular sample having a diameter of 8 mm is punched out.
• the obtained sample is subjected to dynamic viscoelasticity measurement using a rheometer under the conditions of a measuring tool: 8 mm diameter parallel plate, a frequency: 1 Hz, a measuring temperature: -50 to 150°C, and a heating rate: 5°C/min, and the storage shear modulus G' at -20°C is read.
• Examples of methods for adjusting G' (-20°C) of requirement (1) in the pressure-sensitive adhesive sheet to the above range include methods for adjusting the composition and molecular weight of the (meth)acrylic copolymer (A) and the type and amount of the photocurable compound (B). However, the methods are not limited to these.
• the pressure-sensitive adhesive sheet according to one embodiment further satisfies the following requirement (2).
• the maximum strain value ( ⁇ max ) when a stress of 2 kPa is applied at 60° C. for 600 seconds is less than 80%.
• a PSA sheet satisfying the requirement (2) has excellent shape stability. Flexibility is particularly required for adhesive sheets used in flexible image display devices, but conventional adhesive sheets tend to have poorer shape stability as they become softer. However, an adhesive sheet that satisfies both the requirement (1) and the requirement (2) can be made to be flexible yet have excellent shape stability. From the standpoint of shape stability, the maximum distortion value ( ⁇ max ) of requirement (2) is preferably 75% or less, more preferably 70% or less, even more preferably 60% or less, particularly preferably 50% or less, and most preferably 40% or less.
• the maximum distortion value ( ⁇ max ) is usually 0% or more, but from the viewpoint of excellent conformability to unevenness when the adherend surface has unevenness, the maximum distortion value ( ⁇ max ) of requirement (2) is preferably 1% or more, more preferably 2% or more, and even more preferably 3% or more.
• the upper and lower limits of the maximum distortion value ( ⁇ max ) of the requirement (2) can be combined in any combination.
• the maximum distortion value ( ⁇ max ) of the requirement (2) is preferably 1% to 75%, more preferably 2% to 70%, even more preferably 3% to 60%, particularly preferably 5% to 50%, and most preferably 8% to 40%.
• the measurement of the maximum distortion value ( ⁇ max ) in the requirement (2) is carried out, for example, as follows.
• the pressure-sensitive adhesive sheet is repeatedly laminated to adjust the thickness to 0.7 to 1.0 mm, and then a circular sample having a diameter of 8 mm is punched out.
• the strain value of the obtained sample after applying a pressure of 2 kPa at 60° C. for 600 seconds using a rheometer is read as the maximum strain value ( ⁇ max ).
• Examples of a method for adjusting the maximum distortion value ( ⁇ max ) of requirement (2) to fall within the above range include a method for adjusting the composition or molecular weight of the (meth)acrylic copolymer (A) or the type or amount of the photocurable compound (B) added, and a method for adjusting the amount of active energy ray irradiation, although the method is not limited to these.
• the pressure-sensitive adhesive sheet according to the embodiment further satisfies the following requirement (3).
• the storage shear modulus at 30° C. (G′(30° C.)) obtained by dynamic viscoelastic measurement in a shear mode at a frequency of 1 Hz is 1,000 kPa or less.
• G'(30°C) of requirement (3) is preferably 500 kPa or less, more preferably 200 kPa or less, even more preferably 100 kPa or less, particularly preferably 50 kPa or less, and most preferably 40 kPa or less.
• G'(30°C) of requirement (3) is preferably 1 kPa or more, more preferably 2 kPa or more, even more preferably 5 kPa or more, and particularly preferably 10 kPa or more.
• the upper and lower limits of G'(30°C) of requirement (3) can be combined in any combination.
• 1 kPa or more and 500 kPa or less are preferable, 2 kPa or more and 200 kPa or less are more preferable, 5 kPa or more and 100 kPa or less are even more preferable, 10 kPa or more and 50 kPa or less are particularly preferable, and 15 kPa or more and 40 kPa or less are most preferable.
• the pressure-sensitive adhesive sheet according to the embodiment further satisfies the following requirement (4).
• the storage shear modulus at 80° C. (G′(80° C.)) obtained by dynamic viscoelastic measurement in a shear mode at a frequency of 1 Hz is 10 kPa or more.
• Adhesive sheets that satisfy requirement (4) have excellent shape stability and durability at high temperatures.
• G'(80°C) of requirement (4) is preferably 20 kPa or more, more preferably 30 kPa or more, even more preferably 40 kPa or more, particularly preferably 50 kPa or more, and most preferably 60 kPa or more.
• G'(80°C) of requirement (4) is preferably 500 kPa or less, more preferably 400 kPa or less, even more preferably 300 kPa or less, and particularly preferably 200 kPa or less.
• the lower and upper limits of G'(80°C) of requirement (4) can be combined in any combination.
• G'(80°C) in requirement (4) is preferably 20 kPa or more and 500 kPa or less, more preferably 30 kPa or more and 400 kPa or less, even more preferably 40 kPa or more and 300 kPa or less, particularly preferably 50 kPa or more and 200 kPa or less, and most preferably 60 kPa or more.
• the method for measuring G'(30°C) in requirement (3) and the method for measuring G'(80°C) in requirement (4) are the same as the measurement of G'(-20°C) in requirement (1), except that the storage shear modulus (G') values are read at 30°C and 80°C.
• Methods for adjusting the storage shear modulus G' of the pressure-sensitive adhesive sheet to fall within the above range include, for example, a method for adjusting the composition and molecular weight of the (meth)acrylic copolymer (A), a method for adjusting the type and amount of the photocurable compound (B) and photoinitiator (C), and a method for adjusting the amount of active energy ray irradiation.
• the methods are not limited to these.
• the pressure-sensitive adhesive sheet according to the embodiment further satisfies the following requirement (5).
• the glass transition temperature (Tg) defined as the maximum value of Tan ⁇ obtained by dynamic viscoelasticity measurement in a shear mode at a frequency of 1 Hz is ⁇ 20° C. or lower.
• the Tg of requirement (5) is preferably ⁇ 25° C. or lower, more preferably ⁇ 28° C. or lower, even more preferably ⁇ 30° C. or lower, and particularly preferably ⁇ 35° C. or lower.
• the lower limit is usually ⁇ 80° C.
• the Tg of requirement (5) is preferably ⁇ 80° C. or higher and ⁇ 20° C. or lower, more preferably ⁇ 80° C. or higher and ⁇ 25° C. or lower, even more preferably ⁇ 75° C. or higher and ⁇ 28° C. or lower, particularly preferably ⁇ 70° C. or higher and ⁇ 30° C. or lower, and most preferably ⁇ 65° C. or higher and ⁇ 35° C. or lower.
• the measurement of Tg in the requirement (5) is carried out, for example, as follows.
• the pressure-sensitive adhesive sheet is repeatedly laminated to adjust the thickness to 0.7 to 1.0 mm (for example, 0.8 mm), and then a circular sample having a diameter of 8 mm is punched out.
• the obtained sample is subjected to dynamic viscoelasticity measurement using a rheometer under the conditions of a measuring tool: 8 mm diameter parallel plate, a frequency: 1 Hz, a measuring temperature: -50 to 150°C, and a heating rate: 5°C/min, and the temperature at which the Tan ⁇ value is maximized is read from the obtained dynamic viscoelasticity spectrum.
• Examples of the method for adjusting the Tg of requirement (5) to the above range include a method for adjusting the composition and molecular weight of the (meth)acrylic copolymer (A), a method for adjusting the type and amount of the photocurable compound (B) and the photoinitiator (C), and a method for adjusting the amount of active energy ray irradiation.
• the method is not limited to these methods.
• the pressure-sensitive adhesive sheet according to this embodiment further satisfies the following requirement (6).
• a pressure-sensitive adhesive sheet satisfying the requirement (6) has excellent restoring properties when folded.
• the restoration rate of requirement (6) is preferably 70% or more, more preferably 80% or more, even more preferably 85% or more, particularly preferably 87% or more, and most preferably 90% or more.
• the upper limit is usually 100%, but from the viewpoint of improving adhesive strength, the restoration rate of requirement (6) is preferably 99% or less, more preferably 98% or less.
• the lower limit and the upper limit of the restoration rate of requirement (6) can be arbitrarily combined.
• the restoration rate is preferably 60% or more and 100% or less, more preferably 70% or more and 99% or less, even more preferably 80% or more and 98% or less, even more preferably 85% or more and 98% or less, particularly preferably 87% or more and 98% or less, and most preferably 90% or more and 98% or less.
• the measurement of the restoration rate in accordance with requirement (6) is carried out, for example, as follows.
• the pressure-sensitive adhesive sheet is repeatedly laminated to adjust the thickness to 0.7 to 1.0 mm, and then a circular sample with a diameter of 8 mm is punched out.
• a rheometer is used to measure the strain ( ⁇ max ) after applying a pressure of 2 kPa at 60°C for 600 seconds, and the strain ( ⁇ min ) after 600 seconds have passed since the stress was removed.
• the obtained values are substituted into the following formula to calculate the recovery rate.
• Recovery rate (%) [( ⁇ max ⁇ min )/ ⁇ max ] ⁇ 100
• Examples of methods for adjusting the recovery rate of requirement (6) to fall within the above range include a method of adjusting the composition and molecular weight of the (meth)acrylic copolymer (A), a method of adjusting the type and amount of the photocurable compound (B) and photoinitiator (C), and a method of adjusting the amount of active energy ray irradiation.
• the present invention is not limited to these methods.
• the pressure-sensitive adhesive sheet according to this embodiment further satisfies the following requirement (7).
• the gel fraction is 30% or more.
• a pressure-sensitive adhesive sheet satisfying the requirement (7) has excellent cohesive strength.
• the gel fraction of requirement (7) is preferably 35% or more, more preferably 40% or more, and even more preferably 45% or more.
• the gel fraction of requirement (7) is preferably 98% or less, more preferably 95% or less, and even more preferably 92% or less.
• the lower limit and the upper limit of the gel fraction of requirement (7) can be arbitrarily combined. Specifically, the gel fraction is preferably 30% or more and 98% or less, more preferably 35% or more and 98% or less, even more preferably 40% or more and 95% or less, and particularly preferably 45% or more and 92% or less.
• the gel fraction of the requirement (7) is measured, for example, as follows.
• the pre-weighed adhesive sheet is wrapped in a 150 mesh SUS wire net and immersed in ethyl acetate for 24 hours at 23° C. Then, it is dried at 70° C. for 4.5 hours, and the mass of the adhesive before and after immersion in ethyl acetate is measured, and the difference between the two masses is the mass of the insoluble adhesive remaining in the wire net (mass after immersion).
• the percentage of the mass of the insoluble adhesive remaining in the wire net (mass after immersion) to the mass of the adhesive before immersion in ethyl acetate (mass before immersion) is calculated as the gel fraction (%) of requirement (6).
• Examples of the method of adjusting the gel fraction of requirement (7) to the above range include a method of adjusting the composition or molecular weight of the (meth)acrylic copolymer (A) or the type or amount of the photocurable compound (B) added, and a method of adjusting the amount of active energy radiation irradiation.
• the method is not limited to these methods.
• the pressure-sensitive adhesive sheet according to the embodiment further satisfies the following requirement (8).
• the adhesive strength to the surface of the polyester film is 0.5 N/cm or more at 23° C., 50% RH, a peel angle of 180°, and a peel speed of 300 mm/min.
• a pressure-sensitive adhesive sheet satisfying the requirement (8) has excellent adhesion and is unlikely to undergo delamination even when a laminate attached to an adherend such as a component of an image display device is folded, and therefore has excellent durability.
• the adhesive strength of requirement (8) is preferably 1 N/cm or more, more preferably 2 N/cm or more, even more preferably 3 N/cm or more, and particularly preferably 4 N/cm or more.
• the upper limit of the adhesive strength of requirement (8) is not particularly limited, and may be, for example, 20 N/cm or less.
• the adhesive strength of requirement (8) is preferably 1 N/cm or more and 20 N/cm or less, more preferably 2 N/cm or more and 20 N/cm or less, even more preferably 3 N/cm or more and 18 N/cm or less, and particularly preferably 4 N/cm or more and 18 N/cm or less.
• the measurement of the adhesive strength in accordance with requirement (8) is carried out, for example, as follows.
• a polyester film is attached to one side of the adhesive sheet as a backing film, and the sheet is cut into a strip of 10 mm wide x 150 mm long to obtain a test piece.
• the test piece is attached to a polyester film previously attached to soda lime glass, and autoclaved (60°C, gauge pressure 0.2 MPa, 20 minutes) to obtain an adhesive strength measurement sample.
• the adhesive sheet is peeled off together with the backing film from the polyester film attached to the soda lime glass under the conditions of 23°C, 50% RH, peel angle 180°, and peel speed 300 mm/min, and the tensile strength (N/cm) is measured with a load cell to obtain the adhesive strength.
• the pressure-sensitive adhesive sheet according to the embodiment further satisfies the following requirement (9).
• the adhesive strength to the surface of the polyester film is 0.1 N/cm or more at 60° C., 10% RH, a peel angle of 180°, and a peel speed of 300 mm/min.
• a PSA sheet satisfying the requirement (9) has excellent durability at high temperatures.
• the adhesive strength of requirement (9) is preferably 0.2 N/cm or more, more preferably 0.3 N/cm or more, even more preferably 0.4 N/cm or more, and particularly preferably 0.5 N/cm or more.
• the upper limit of the adhesive strength of requirement (9) is not particularly limited, and may be, for example, 20 N/cm or less.
• the adhesive strength of requirement (9) is preferably 0.2 N/cm or more and 20 N/cm or less, more preferably 0.3 N/cm or more and 20 N/cm or less, even more preferably 0.4 N/cm or more and 18 N/cm or less, and particularly preferably 0.5 N/cm or more and 18 N/cm or less.
• the measurement of adhesive strength under requirement (9) is the same as that under requirement (8), except that the test environment is 60°C and 10% RH.
• Methods for adjusting the adhesive strength include, for example, adjusting the composition and molecular weight of the (meth)acrylic copolymer (A), adjusting the type and amount of the photocurable compound (B) and photoinitiator (C), and adjusting the amount of active energy ray irradiation.
• the methods are not limited to these.
• the pressure-sensitive adhesive sheet according to the embodiment preferably further satisfies the following requirement (10).
• the total light transmittance is 80% or more.
• a PSA sheet satisfying the requirement (10) has excellent transparency and is useful for applications requiring transparency, such as image display devices.
• the total light transmittance of the requirement (10) is preferably 85% or more, and more preferably 90% or more.
• the total light transmittance of the requirement (10) is preferably 85% or more and 100% or less, and more preferably 90% or more and 100% or less.
• the measurement of the total light transmittance in the requirement (10) is carried out in accordance with the standard JIS-K7361-1 (ISO-13468-1).
• the pressure-sensitive adhesive sheet according to the embodiment further satisfies the following requirement (11).
• (11) Haze is 5% or less.
• a PSA sheet satisfying the requirement (11) has excellent transparency and is useful for applications requiring transparency, such as image display devices.
• the haze of requirement (11) is preferably 4% or less, more preferably 2% or less, and even more preferably 1% or less.
• the haze of requirement (11) is preferably 0% or more and 4% or less, more preferably 0% or more and 2% or less, and even more preferably 0% or more and 1% or less.
• the measurement of the haze in the requirement (11) is carried out in accordance with the standard JIS-K7136 (ISO-14782).
• Methods for adjusting the total light transmittance of requirement (10) and the haze of requirement (11) include, for example, adjusting the composition of the (meth)acrylic acid ester copolymer, using a colorless photoinitiator, or not containing a colorant. Also, coloring due to heating or deterioration over time may be suppressed by using an antioxidant. However, the methods are not limited to these.
• the pressure-sensitive adhesive sheet according to the embodiment may have a single layer structure or a multi-layer structure.
• each of the multiple layers is formed from a pressure-sensitive adhesive composition containing the (meth)acrylic copolymer (A).
• the thickness of the adhesive sheet according to the embodiment is preferably 5 ⁇ m or more, more preferably 10 ⁇ m or more, even more preferably 15 ⁇ m or more, and particularly preferably 20 ⁇ m or more, because it is easy to reduce stress during bending or curving and to make a flexible image display device to which the adhesive sheet is applied thin, so the thickness of the adhesive sheet according to the embodiment is preferably 100 ⁇ m or less, more preferably 80 ⁇ m or less, even more preferably 70 ⁇ m or less, and particularly preferably 60 ⁇ m or less.
• the lower limit and upper limit of the thickness of the adhesive sheet can be arbitrarily combined.
• the thickness of the adhesive sheet is preferably 5 ⁇ m or more and 100 ⁇ m or less, more preferably 10 ⁇ m or more and 80 ⁇ m or less, even more preferably 15 ⁇ m or more and 70 ⁇ m or less, and particularly preferably 20 ⁇ m or more and 60 ⁇ m or less.
• the pressure-sensitive adhesive sheet according to the embodiment preferably has a release film laminated on at least one surface thereof, and more preferably has release films laminated on both surfaces thereof, prior to lamination.
• release films are provided on both sides of the adhesive sheet, it is preferable to use a laminate structure in which a light release film with a relatively low release force and a heavy release film with a relatively high release force are laminated.
• one release film (light release film) is peeled off to expose one side of the adhesive sheet, and the image display device component (first member) is bonded to the other side of the adhesive sheet exposed by peeling off the other release film (heavy release film), and the image display device component (second member) is bonded to the other side of the adhesive sheet.
• the release film examples include polyester film, polyolefin film, polycarbonate film, polystyrene film, acrylic film, triacetyl cellulose film, and fluororesin film.
• polyester film and polyolefin film are preferred, and polyester film is more preferred.
• the release film since the release film is easily peeled off from the pressure-sensitive adhesive sheet after irradiation with active energy rays, it is preferable that the release film be a film having a peel strength of 0.1 N/cm or less when measured under conditions of a peel angle of 180° and a peel speed of 300 mm/min.
• the thickness of the release film is preferably 25 ⁇ m or more and 500 ⁇ m or less, more preferably 38 ⁇ m or more and 250 ⁇ m or less, and even more preferably 50 ⁇ m or more and 200 ⁇ m or less.
• the lower limit and upper limit of the thickness of the release film can be arbitrarily combined.
• the laminate for an image display device has two image display device components laminated together via the pressure-sensitive adhesive sheet of the present invention.
• the adhesive sheet of the present invention has excellent flexibility and therefore excellent conformability to uneven surfaces, and can conform and deform even if the surface of a component of an image display device has steps, absorbing the steps and bonding two components of an image display device together.
• Examples of image display device components constituting the present laminate for image display devices include flat panel image display device components and flexible image display device components.
• image display device components include flexible displays such as liquid crystal displays and organic electroluminescence (EL) displays, cover lenses (cover films), polarizing plates, polarizers, retardation films, barrier films, viewing angle compensation films, brightness improvement films, contrast improvement films, diffusion films, semi-transmissive reflective films, electrode films, transparent conductive films, metal mesh films, touch sensor films, light-emitting elements, PSA, color filters, and flexible printed circuit boards. Any one of these or two of them can be used in combination. Examples of combinations include a combination of a flexible display and other image display device components, and a combination of a cover lens and other image display device components.
• the material of the image display device components is not particularly limited, and examples thereof include resin sheets mainly composed of resins such as urethane resin, cycloolefin resin, triacetyl cellulose resin, (meth)acrylate resin, epoxy resin, polyimide resin, and polyester resin, thin film glass, and metal.
• resin sheets mainly composed of resins such as urethane resin, cycloolefin resin, triacetyl cellulose resin, (meth)acrylate resin, epoxy resin, polyimide resin, and polyester resin, thin film glass, and metal.
• the flexible image display device component means a bendable member, such as a member used in an image display device having a curved surface shape or a member that can be repeatedly bent.
• the flexible image display device component is a member that can be fixed to a curved shape with a curvature radius of 25 mm or more, and more preferably, a member that can withstand bending action with a curvature radius of less than 25 mm, more preferably, less than 3 mm.
• the material of such a member is preferably a resin sheet mainly composed of at least one resin selected from the group consisting of urethane resin, cycloolefin resin, triacetyl cellulose resin, (meth)acrylate resin, epoxy resin, polyimide resin, polyester resin, etc.
• the resin is preferably at least one selected from the group consisting of polyimide resin, polyester resin, and cycloolefin resin, and among them, polyester resin, particularly polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polyethylene terephthalate (PET) resin is preferable.
• the term "main component” refers to a component that has the largest mass ratio among the components constituting the resin sheet.
• the main component is preferably 50 mass% or more, more preferably 55 mass% or more, and even more preferably 60 mass% or more, based on the mass of the resin sheet.
• the image display device member may have steps on its surface. For example, various irregularities may be present on the contact surface of the image display device member with the pressure-sensitive adhesive sheet due to wiring, printing, pattern development, surface treatment, embossing, etc.
• the height difference of the step of the image display device component is preferably 2 ⁇ m or more, more preferably 3 ⁇ m or more, and even more preferably 4 ⁇ m or more, while it is preferably 10 ⁇ m or less, more preferably 8 ⁇ m or less, even more preferably 7 ⁇ m or less, and particularly preferably 6 ⁇ m or less.
• the lower limit and upper limit of the height difference of the step can be arbitrarily combined.
• the height difference is preferably 2 ⁇ m or more and 8 ⁇ m or less, more preferably 3 ⁇ m or more and 7 ⁇ m or less, and even more preferably 4 ⁇ m or more and 6 ⁇ m or less.
• the step that the image display device component has on the surface that comes into contact with the adhesive sheet can be, for example, unevenness with a height difference of 2 to 10 ⁇ m and spaced at intervals of 10 mm or less.
• the thickness of the laminate for an image display device according to the embodiment is preferably 0.02 mm or more, more preferably 0.03 mm or more, and even more preferably 0.05 mm or more. Since the laminate can be made thinner, the thickness of the laminate for an image display device according to the embodiment is preferably 1.0 mm or less, more preferably 0.7 mm or less, and even more preferably 0.5 mm or less. The lower and upper thickness limits of the laminate for an image display device can be arbitrarily combined. Specifically, the thickness is preferably 0.02 mm or more and 1.0 mm or less, more preferably 0.03 mm or more and 0.7 mm or less, and even more preferably 0.05 mm or more and 0.5 mm or less.
• the method for producing the laminate for an image display device according to the embodiment is not particularly limited.
• the pressure-sensitive adhesive composition may be applied onto a component of an image display device to form a pressure-sensitive adhesive sheet, or a pressure-sensitive adhesive sheet with a release film may be formed in advance and then attached to the component of an image display device.
• the method of laminating the adhesive sheet to the stepped surface of the image display device component is not particularly limited, and known methods such as roll lamination, press lamination using parallel plates, and diaphragm lamination can be used.
• the lamination environment may be either an atmospheric lamination method in which lamination is performed at normal pressure, or a vacuum lamination method in which lamination is performed under reduced pressure.
• the heating temperature during the heat treatment is preferably from 40°C to 100°C, more preferably from 50°C to 90°C, and even more preferably from 55°C to 85°C.
• a press pressure may be applied to the laminate in addition to the heat treatment.
• pressure treatment using an autoclave may be carried out in addition to the heat treatment.
• ⁇ Flexible image display device Yet another embodiment of the present invention relates to a flexible image display device.
• the term "flexible image display device” refers to an image display device that leaves no traces of bending even when repeatedly bent, curved, or wound, and quickly recovers to its original state when released from the bent, curved, or wound state, and can display images without distortion.
• a flexible image display device includes the laminate for an image display device of the present invention.
• the laminate for an image display device is disposed on the side opposite to the viewing side of the image display panel, i.e., on the light source side.
• other members may be further laminated between the image display panel and the laminate for an image display device of the present invention, or on the opposite side of the laminate for an image display device of the present invention to the image display panel. Examples of the other members include the same image display device constituent members exemplified in the description of the laminate for an image display device of the embodiment.
• the adhesive sheet conforms to and absorbs the step, suppressing the generation of air bubbles, and also suppresses delamination and cracking even when the device is bent, curved, or wound in a low-temperature environment.
• the photocurable pressure-sensitive adhesive sheet according to the embodiment is an adhesive sheet prior to being irradiated with light, and is formed from a pressure-sensitive adhesive composition containing the (meth)acrylic copolymer (A).
• the photocurable adhesive sheet of the present invention is a photocurable adhesive sheet in which the (meth)acrylic copolymer (A) has a constituent unit derived from a monomer M that generates an active species excited by irradiation with active energy rays, and which satisfies the following requirements (1') and (2'): Requirement (1')
• the photocurable adhesive sheet has a shear storage modulus (G'(-20°C)) at -20°C, measured by dynamic viscoelasticity measurement in a shear mode at a frequency of 1 Hz when irradiated with active energy rays having a wavelength of 365 nm at an integrated light dose in the range of 1000 to 5000 mJ/cm2, of 10 kPa or more and 1000 kPa or less; and Requirement (2') When the photocurable adhesive sheet is irradiated with active energy rays having a wavelength of 365 nm at an integrated light amount within a range of 1000 to 5000
• ⁇ Adhesive Composition> Yet another embodiment of the present invention relates to a pressure sensitive adhesive composition.
• the pressure-sensitive adhesive composition according to the embodiment is used for forming a photocurable pressure-sensitive adhesive sheet and a pressure-sensitive adhesive sheet, and contains a (meth)acrylic copolymer (A).
• the adhesive composition is the same as that described for the adhesive sheet.
• Non-volatile content volatile content
• Volatile content (%) 100 - non-volatile content (%)
• the release film on one side was removed from the pressure-sensitive adhesive sheet with release film prepared in each example, and a polyethylene terephthalate (PET) film (thickness 50 ⁇ m) was attached as a backing film with a hand roller. This was cut into a strip of width 10 mm x length 150 mm, and the remaining release film was peeled off to expose the adhesive surface, which was then attached with a hand roller to a PET film (manufactured by Mitsubishi Chemical Corporation, Diafoil S-100, thickness 50 ⁇ m) that had been previously attached to soda-lime glass.
• PET polyethylene terephthalate
• the obtained laminate was subjected to autoclave treatment (60 ° C, gauge pressure 0.2 MPa, 20 minutes) for finish attachment to prepare a sample for measuring adhesive strength.
• the obtained adhesive strength measurement sample was pulled at an angle of 180° at a peeling rate of 300 mm/min in an atmosphere of 23°C, 50% RH or 60°C, 10% RH, while the adhesive sheet together with the backing film was peeled off from the PET film attached to the soda lime glass, and the tensile strength (N/cm) was measured with a load cell to obtain the adhesive strength.
• Glass Transition Temperature From the dynamic viscoelasticity spectrum obtained by measuring the storage shear modulus G', the temperature at which Tan ⁇ becomes maximum was read as the glass transition temperature (Tg).
• the release film was removed from the pressure-sensitive adhesive sheet with release film prepared in each example, and this was used as a sample.
• a pre-weighed sample was wrapped in a 150 mesh SUS wire net and immersed in ethyl acetate at 23° C. for 24 hours. The sample was then dried at 70° C. for 4.5 hours, and the mass of the insoluble sample remaining in the wire net after immersion in ethyl acetate was measured. The mass percentage of the insoluble sample remaining in the wire net relative to the mass of the sample before immersion in ethyl acetate was calculated as the gel fraction (%).
• MBP 4-methacryloyloxybenzophenone (monomer M having a structure that generates a radical by abstracting hydrogen from a hydrogen donor upon excitation).
• HHMPMA 2-[4-(2-hydroxy-2-methyl-1-oxopropyl)phenoxy]ethyl methacrylate (monomer M having a structure that generates radicals by cleaving its own single bond upon excitation).
• 2EHA 2-ethylhexyl acrylate.
• nBA n-butyl acrylate.
• 4HBA 4-hydroxybutyl acrylate.
• SLMA a mixture of an alkyl methacrylate having an alkyl group with 12 carbon atoms and an alkyl methacrylate having an alkyl group with 13 carbon atoms ("Acryester SL" manufactured by Mitsubishi Chemical Corporation).
• AMBN 2,2'-azobis(2-methylbutyronitrile).
• B-1 Bifunctional urethane acrylate ("Shiko UV-3700B” manufactured by Mitsubishi Chemical Corporation, Mw: 38,000).
• B-2 Propoxylated pentaerythritol tri- and tetraacrylate (“ATM-4PL” manufactured by Shin-Nakamura Chemical Co., Ltd.).
• B-3 Monofunctional urethane acrylate having a polypropylene glycol skeleton (but containing a small amount of bifunctionality) (AGC "PEM-X264", Mw: 15,000)
• C-1 A mixture of 4-methylbenzophenone and 2,4,6-trimethylbenzophenone (hydrogen abstraction type) ("Ezacure TZT" manufactured by IGM)
• Example 1 Provide of (meth)acrylic copolymer> A four-neck flask equipped with a stirrer, a thermometer, a cooling tube, and a nitrogen gas inlet was charged with 25 parts of ethyl acetate, 2 parts of isopropyl alcohol (IPA), and 6.8 parts of a macromonomer (SLMA-MM) solution (concentration 50% by mass), and the external temperature was raised to 85 ° C. in a water bath under nitrogen gas aeration.
• IPA isopropyl alcohol
• SLMA-MM macromonomer
• the composition obtained by the production of the (meth)acrylic copolymer was used as the adhesive composition as it is.
• This adhesive composition was spread in a sheet shape on a release film having a thickness of 100 ⁇ m (a PET film treated with silicone release, manufactured by Mitsubishi Chemical Corporation) so that the thickness after drying was 50 ⁇ m.
• the sheet-shaped adhesive composition together with the release film was placed in a dryer heated to 90° C. and held for 10 minutes to dry the adhesive composition (volatilize the solvent contained in the adhesive composition).
• a release film having a thickness of 75 ⁇ m (a PET film treated with silicone release, manufactured by Mitsubishi Chemical Corporation) was laminated on the dried sheet-shaped adhesive composition.
• the pressure-sensitive adhesive composition was irradiated with active energy rays through the release film so that the integrated light amount at a wavelength of 365 nm was 4000 mJ/ cm2, thereby obtaining a pressure-sensitive adhesive sheet with release film in which release films were laminated on both the front and back sides of a 50 ⁇ m-thick pressure-sensitive adhesive sheet.
• Examples 2 to 16, Comparative Example 1 A pressure-sensitive adhesive sheet with a release film was produced in the same manner as in Example 1, except that the copolymerization composition of the (meth)acrylic copolymer (A), the blending amount of the pressure-sensitive adhesive composition, and the amount of active energy ray irradiation were changed as shown in Tables 1 and 2.
• the blending amounts of the photocurable compound (B) and the photoinitiator (C) are the ratios (parts) to 100 parts of the (meth)acrylic copolymer.
• Tables 1 and 2 The results of the measurements and evaluations of the pressure-sensitive adhesive sheets of each example are shown in Tables 1 and 2.
• the pressure-sensitive adhesive sheets of the Examples were pressure-sensitive adhesive sheets having high sensitivity to active energy rays and excellent flexibility and shape stability.
• the adhesive sheets of Examples 9 to 16 in which the monomer M has a structure in which its own single bond is cleaved and decomposed upon excitation to generate radicals, showed a tendency to have improved adhesive strength compared to those using a monomer M having a hydrogen abstraction type radical generating group.
• the pressure-sensitive adhesive sheet of the comparative example had a high maximum distortion value ( ⁇ max ) when a stress of 2 kPa was applied at 60° C. for 600 seconds, and was poor in shape stability.
• the present invention can provide an adhesive sheet that is highly sensitive to active energy rays and can be cured with high efficiency, an adhesive sheet with a release film that uses the adhesive sheet, an adhesive sheet for a component of a flexible image display device, a laminate for an image display device, and a flexible image display device.

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