Adhesive composition, adhesive layer, optical film with adhesive layer, and display device

Abstract

The present invention addresses the problem of providing an adhesive that exhibits excellent heat-resistant durability and easy reworkability. [Solution] This adhesive composition contains a (meth) acrylic resin (A), a crosslinking agent (B), and a silane compound (C), wherein the (meth) acrylic resin (A) contains a structural unit derived from an alkyl methacrylate (a) having a homopolymer glass transition temperature of 30 DEG C or higher, a structural unit derived from a hydroxyl group-containing (meth) acrylate (b), and a structural unit derived from a carboxyl group-containing monomer (c), and the silane compound (C) contains a compound represented by formula (i).

Description

Technical Field

[0001] The present invention relates to an adhesive composition, an adhesive layer comprising the adhesive composition, and an optical film with an adhesive layer. Background Art

[0002] Optical films such as polarizing plates used in image display devices such as liquid crystal displays (LCDs) and organic electroluminescent (OLED) displays are often bonded to other components (e.g., image display elements such as liquid crystal cells in LCDs) through an adhesive layer. If any defects are detected after bonding an optical film to another component through an adhesive layer, it may be necessary to remove the bonded optical film with the adhesive layer and then reattach a new optical film in order to reuse the component.

[0003] Patent Document 1 proposes an adhesive composition containing a (meth)acrylic resin and a specific silane compound as an adhesive composition having both durability and heavy-duty properties.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2016-65156 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] In recent years, adhesives used in optical films for automotive applications, for example, have been required to exhibit improved heat resistance and durability in harsher environments, as well as excellent reworkability. Reworkability refers to the ability to peel the optical film together with the adhesive layer during rework. Reworkability is considered excellent if the adhesive-coated optical film can be easily peeled from other components and the same or another adhesive-coated optical film can be easily reattached to the surface of the other component after peeling. However, achieving both heat resistance and reworkability is difficult with adhesives.

[0009] An object of the present invention is to provide an adhesive exhibiting excellent heat-resistant durability and easy reworkability.

[0010] Means for solving problems

[0011] The present invention provides the following adhesive composition, adhesive layer, adhesive layer-attached optical film, and display device.

[0012] [1] An adhesive composition comprising a (meth)acrylic resin (A), a crosslinking agent (B), and a silane compound (C), wherein:

[0013] The (meth)acrylic resin (A) comprises a structural unit derived from an alkyl methacrylate (a) having a homopolymer glass transition temperature of 30° C. or higher, a structural unit derived from a hydroxyl group-containing (meth)acrylate (b), and a structural unit derived from a carboxyl group-containing monomer (c).

[0014] The aforementioned silane compound (C) includes a compound represented by the following formula (i),

[0015] [Chemical Formula 1]

[0016]

[0017] [In formula (i),

[0018] A 1 represents an alkyl group having 1 to 5 carbon atoms,

[0019] A 2 and A 3 each independently represents an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms,

[0020] L represents an alkylene group having 8 to 20 carbon atoms or a group in which at least one methylene group constituting the alkylene group is replaced by a group selected from -NH- and -O-,

[0021] X represents an epoxy group or an alicyclic epoxy group].

[0022] [2] The adhesive composition according to [1], comprising 0.01 parts by mass or more and 2.0 parts by mass or less of the silane compound (C) relative to 100 parts by mass of the (meth)acrylic resin (A).

[0023] [3] The adhesive composition according to [1] or [2], which contains 1 part by mass or more and 15 parts by mass or less of structural units derived from the alkyl methacrylate (a) having a homopolymer glass transition temperature of 30°C or more, and 0.3 parts by mass or more and 5.5 parts by mass or less of structural units derived from the hydroxyl group-containing (meth)acrylate (b), relative to 100 parts by mass of all structural units constituting the (meth)acrylic resin (A).

[0024] [4] The adhesive composition according to any one of [1] to [3], wherein the mass ratio (c) / (b) of the structural unit derived from the carboxyl group-containing monomer (c) to the structural unit derived from the hydroxyl group-containing (meth)acrylate (b) is 0.06 or more and 1.0 or less.

[0025] [5] The adhesive composition according to any one of [1] to [4], wherein the glass transition temperature of the homopolymer of the alkyl methacrylate (a) is 30°C or higher and the glass transition temperature of the homopolymer is 80°C or higher.

[0026] [6] The adhesive composition according to any one of [1] to [5], wherein the alkyl methacrylate (a) having a homopolymer glass transition temperature of 30°C or higher comprises at least one selected from methyl methacrylate, t-butyl methacrylate, isobornyl methacrylate, and cyclohexyl methacrylate.

[0027] [7] The adhesive composition according to any one of [1] to [6], wherein the weight average molecular weight of the (meth)acrylic resin (A) is 1,000,000 to 3,200,000.

[0028] [8] The adhesive composition according to any one of [1] to [7], wherein in the formula (i), L represents an alkylene group having 8 to 12 carbon atoms or a group in which at least one methylene group constituting the alkylene group is replaced by a group selected from -NH- and -O-.

[0029] [9] The adhesive composition according to any one of [1] to [8], wherein the crosslinking agent (B) comprises an aromatic isocyanate compound, and the adhesive composition contains 0.2 parts by mass or more and 5.0 parts by mass or less of the crosslinking agent (B) per 100 parts by mass of the (meth)acrylic resin (A).

[0030]

[10] An adhesive layer comprising the adhesive composition according to any one of [1] to [9].

[0031]

[11] An optical film with a pressure-sensitive adhesive layer, comprising an optical film and the pressure-sensitive adhesive layer according to

[10] laminated on the optical film.

[0032]

[12] The optical film with a pressure-sensitive adhesive layer according to

[11] , wherein the optical film includes a polarizer.

[0033]

[13] A display device comprising the optical film with an adhesive layer according to

[11] or

[12] .

[0034] Effects of the Invention

[0035] According to the present invention, an adhesive exhibiting excellent heat resistance and durability and easy reworkability can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic cross-sectional view showing an example of the pressure-sensitive adhesive layer-attached optical film according to the present invention.

[0037] Figure 2 This is a schematic cross-sectional view showing another example of the optical film with a pressure-sensitive adhesive layer according to the present invention.

[0038] Figure 3 This is a schematic cross-sectional view showing an example of a display device according to the present invention. DETAILED DESCRIPTION

[0039] Below, with reference to the attached Figure 1 While the embodiments of the present invention are described below, the present invention is not limited to the following embodiments. In all the following drawings, the scales of the components are appropriately adjusted for ease of understanding, and the scales of the components shown in the drawings are not necessarily consistent with the scales of the actual components.

[0040] <Adhesive Composition>

[0041] (1) (Meth)acrylic resin (A)

[0042] The (meth)acrylic resin (A) contained in the adhesive composition of the present invention comprises structural units derived from an alkyl methacrylate (a) (hereinafter also referred to as alkyl methacrylate (a)) having a homopolymer glass transition temperature of 30°C or higher, structural units derived from a hydroxyl group-containing (meth)acrylate (b), and structural units derived from a carboxyl group-containing monomer (c). In this specification, (meth)acrylic acid may refer to either acrylic acid or methacrylic acid. (Meth)acrylate may refer to either acrylic acid or methacrylic acid.

[0043] The alkyl methacrylate (a) is an alkyl methacrylate having a homopolymer glass transition temperature (Tg) of 30°C or higher. The Tg of the homopolymer of the alkyl methacrylate can be determined, for example, using values ​​from literature such as POLYMER HANDBOOK (Wiley-Interscience). From the perspective of heat resistance and durability, the Tg of the homopolymer of the alkyl methacrylate (a) is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 80°C or higher. The upper limit of the Tg of the homopolymer of the alkyl methacrylate (a) is not particularly limited, but is generally 250°C or lower.

[0044] Specific examples of the alkyl methacrylate (a) include methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, propyl methacrylate, isopropyl methacrylate, 3,3-dimethylbutyl methacrylate, 3,3-dimethyl-2-butyl methacrylate, and other alkyl methacrylates having a linear or branched alkyl group with 1 to 6 carbon atoms, as well as n-stearyl methacrylate. The alkyl methacrylate (a) may be an alkyl methacrylate having an alicyclic structure (cycloalkyl methacrylate). The alicyclic structure may be a cycloalkane structure having a carbon number of generally 5 or more, preferably 5 to 7. Specific examples of the alkyl methacrylate having an alicyclic structure include isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentyl methacrylate, trimethylcyclohexyl methacrylate, tert-butylcyclohexyl methacrylate, and 1-adamantyl methacrylate. The alkyl methacrylate (a) may be used alone or in combination of two or more.

[0045] The alkyl methacrylate (a) is preferably an alkyl methacrylate having a linear or branched alkyl group having 1 to 4 carbon atoms, or an alkyl methacrylate having an alicyclic structure, and particularly preferably methyl methacrylate, t-butyl methacrylate, isobornyl methacrylate, or cyclohexyl methacrylate.

[0046] From the perspectives of ease of reworkability and heat resistance and durability, the content of the structural units derived from the alkyl methacrylate (a) is preferably from 1 to 15 parts by mass, more preferably from 3 to 13 parts by mass, even more preferably from 4 to 12 parts by mass, and particularly preferably from 5 to 11 parts by mass, relative to 100 parts by mass of all structural units constituting the (meth)acrylic resin (A). Within this range, the mechanical strength of the adhesive is enhanced by improving its cohesiveness, while maintaining the adhesive's flexibility and adhesiveness, thereby contributing to improved heat resistance and durability.

[0047] The hydroxyl group-containing (meth)acrylate (b) may be a (meth)acrylate containing one or more hydroxyl groups in the molecular chain. Specific examples of the hydroxyl group-containing (meth)acrylate (b) include compounds represented by the following formula (1):

[0048] [Chemical Formula 2]

[0049]

[0050] [In formula (1),

[0051] n represents an integer from 1 to 5,

[0052] A 1 represents a hydrogen atom or an alkyl group,

[0053] X 1 represents a methylene group which may have a substituent.

[0054] When n is 2 or more, the aforementioned X 1 Optional same or different].

[0055] In formula (1), A 1 Examples of the alkyl group include alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, and hexyl. Among them, methyl is preferred.

[0056] In formula (1), X 1 The substituents that the methylene group may have include, for example, a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), an alkyl group (for example, an alkyl group having 1 to 10 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, etc., preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms), a cycloalkyl group (cyclopentyl, cyclohexyl, etc.), an aryl group (phenyl, alkylphenyl (tolyl, xylyl, etc.)), an aralkyl group (benzyl, etc.), an alkoxy group (for example, a methoxy, ethoxy, etc., etc., having 1 to 4 carbon atoms), an alkyl group (for example, a cyclopentyl, cyclohexyl, etc.), an aryl group (phenyl, alkylphenyl (tolyl, xylyl, etc.)), an aralkyl group (benzyl, etc.), an alkoxy group (for example, a methoxy, ethoxy, etc., etc.), an alkyl group (for example, a cyclopentyl, cyclohexyl, etc.), an alkyl group (phenyl, alkylphenyl (tolyl, xylyl, etc.)), an aralkyl group (benzyl, etc.), an alkoxy group (for example, a cyclopentyl, cyclohexyl ... Examples of the present invention include alkylthio groups (e.g., alkylthio groups having 5 to 10 carbon atoms, such as cyclohexyloxy), polyoxyalkylene groups (e.g., ethylene dioxide), cycloalkyloxy groups (e.g., cyclohexyloxy), aralkyloxy groups (e.g., benzyloxy), alkylthio groups (e.g., alkylthio groups having 1 to 4 carbon atoms, such as methylthio and ethylthio), cycloalkylthio groups (e.g., cyclohexylthio), arylthio groups (e.g., thiophenoxy), aralkylthio groups (e.g., benzylthio), acyl groups (e.g., acetyl), nitro, and cyano groups. Among these, halogen atoms, alkyl groups, alkoxy groups, and aryloxy groups are preferred, and alkyl groups (e.g., methyl and ethyl) are particularly preferred.

[0057] In formula (1), n ​​can be, for example, an integer of 1 to 4, preferably an integer of 1 to 3, and more preferably 2. When n is 2 or more, X 1 That is, when n is 2 or more, X 1 It may be composed of an unsubstituted methylene group, an unsubstituted methylene group and a methylene group having a substituent, or a methylene group having a substituent. In addition, when there are two or more substituents in formula (1), the substituents may be the same or different.

[0058] Specific examples of the hydroxyl group-containing (meth)acrylate (b) include: 1-hydroxy C1 to C8 alkyl (meth)acrylates such as 1-hydroxymethyl (meth)acrylate, 1-hydroxyethyl (meth)acrylate, 1-hydroxyheptyl (meth)acrylate, 1-hydroxybutyl (meth)acrylate, and 1-hydroxypentyl (meth)acrylate; 2-hydroxy C2 to C9 alkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxypentyl (meth)acrylate, and 2-hydroxyhexyl (meth)acrylate; 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 3-hydroxypentyl (meth)acrylate, and 3-hydroxyhexyl (meth)acrylate. 3-Hydroxy C3-C10 alkyl (meth)acrylates such as 3-hydroxybutyl (meth)acrylate, 3-hydroxypentyl (meth)acrylate, 3-hydroxyhexyl (meth)acrylate, and 3-hydroxyheptyl (meth)acrylate; 4-hydroxy C4-C11 alkyl (meth)acrylates such as 4-hydroxybutyl (meth)acrylate, 4-hydroxypentyl (meth)acrylate, 4-hydroxyhexyl (meth)acrylate, 4-hydroxyheptyl (meth)acrylate, and 4-hydroxyoctyl (meth)acrylate; 2-chloro-2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate.

[0059] Among these, from the viewpoints of ease of reworkability and heat resistance and durability, preferred are hydroxyl group-containing (meth)acrylates in which n is 2, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate; and hydroxyl group-containing (meth)acrylates in which n is 3, such as 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 3-hydroxypentyl (meth)acrylate. Particularly preferred are hydroxyl group-containing (meth)acrylates in which n is 2, and among these, 2-hydroxyethyl (meth)acrylate is preferred.

[0060] The hydroxyl group-containing (meth)acrylate (b) may be used alone or in combination of two or more. 2-Hydroxyethyl (meth)acrylate is advantageous in forming a uniform crosslinked structure and can improve heat resistance and durability.

[0061] From the viewpoint of easy reworkability and heat resistance and durability, the content of the structural unit derived from the hydroxyl group-containing (meth)acrylate (b) is preferably from 0.3 parts by mass to 5.5 parts by mass, more preferably from 0.3 parts by mass to 4.0 parts by mass, even more preferably from 0.4 parts by mass to 3.0 parts by mass, and particularly preferably from 0.5 parts by mass to 2.5 parts by mass, relative to 100 parts by mass of all structural units constituting the (meth)acrylic resin (A).

[0062] From the viewpoint of easy reworkability and heat resistance and durability, the (meth)acrylic resin (A) is preferably a (meth)acrylic resin containing 1 part by mass or more and 15 parts by mass or less of a structural unit derived from an alkyl methacrylate (a) and 0.3 parts by mass or more and 5.5 parts by mass or less of a structural unit derived from a hydroxyl group-containing (meth)acrylate (b), relative to 100 parts by mass of all structural units constituting the (meth)acrylic resin (A).

[0063] Specific examples of the carboxyl group-containing monomer (c) include: (meth)acrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, carboxylalkyl (meth)acrylates (e.g., carboxylethyl (meth)acrylate, carboxylpentyl (meth)acrylate), etc. Among them, acrylic acid is preferred. Acrylic acid can promote the reaction between the hydroxyl group-containing (meth)acrylate (b) and the crosslinking agent, which is conducive to the formation of a uniform crosslinked structure and can improve heat resistance and durability. The carboxyl group-containing monomer (c) can be used alone or in combination of two or more.

[0064] The content of the structural unit derived from the carboxyl group-containing monomer (c) can be from 0.01 parts by mass to 5.5 parts by mass relative to 100 parts by mass of all structural units constituting the (meth)acrylic resin (A). From the viewpoint of ease of reworkability and heat resistance and durability, it is preferably from 0.05 parts by mass to 3 parts by mass, and more preferably from 0.1 parts by mass to 2 parts by mass.

[0065] From the viewpoint of easy reworkability and heat resistance and durability, the mass ratio (c) / (b) [hereinafter also referred to as mass ratio (c) / (b)] of the structural units derived from the carboxyl group-containing monomer (c) to the structural units derived from the hydroxyl group-containing (meth)acrylate (b) is preferably 0.06 or more and 1.0 or less, more preferably 0.06 or more and 0.9 or less, further preferably 0.08 or more and 0.8 or less, and particularly preferably 0.1 or more and 0.7 or less.

[0066] The (meth)acrylic resin (A) may further contain a structural unit derived from an alkyl acrylate, a structural unit derived from an alkyl methacrylate having a homopolymer glass transition temperature (Tg) of less than 30°C, a structural unit derived from an alkyl (meth)acrylate containing a substituent, a structural unit derived from a (meth)acrylamide-based monomer, a structural unit derived from a styrene-based monomer, a structural unit derived from a vinyl-based monomer, a structural unit derived from a monomer having a plurality of (meth)acryloyl groups in the molecule, and the like.

[0067] The (meth)acrylic resin (A) preferably contains an alkyl acrylate having a homopolymer Tg of less than 0°C. Examples of alkyl acrylates having a homopolymer Tg of less than 0°C include linear or branched alkyl acrylates having an alkyl group having approximately 2 to 12 carbon atoms, such as ethyl acrylate, n-propyl and isopropyl acrylate, n-butyl and isobutyl acrylate, n-pentyl acrylate, n-hexyl and isohexyl acrylate, n-heptyl acrylate, n-octyl and isooctyl acrylate, 2-ethylhexyl acrylate, n-nonyl and isononyl acrylate, n-decyl and isodecyl acrylate, and n-dodecyl acrylate. The alkyl acrylate having a homopolymer Tg of less than 0°C may be an alkyl acrylate having an alicyclic structure (cycloalkyl acrylate). However, from the perspective of conformability to optical films (or flexibility and adhesiveness), an alkyl acrylate having 2 to 10 carbon atoms is preferred, preferably an alkyl acrylate having 3 to 8 carbon atoms, and more preferably an alkyl acrylate having 4 to 6 carbon atoms. Use of these alkyl acrylates can improve followability, and contribute to, for example, peeling resistance, etc. These alkyl acrylates can be used alone or in combination of two or more.

[0068] The (meth)acrylic resin (A) preferably contains an alkyl acrylate whose homopolymer Tg is 0°C or higher. Examples of the alkyl acrylate whose homopolymer Tg is 0°C or higher include methyl acrylate, stearyl acrylate, tert-butyl acrylate, and the like. The alkyl acrylate whose homopolymer Tg is 0°C or higher may be an alkyl acrylate having an alicyclic structure (cycloalkyl acrylate). Only one of these alkyl acrylates may be used, or two or more may be used in combination. The alicyclic structure may be a cycloalkane structure having a carbon number of generally 5 or more, preferably about 5 to 7. Specific examples of the alkyl acrylate whose homopolymer Tg is 0°C or higher include isobornyl acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, cyclododecyl acrylate, methylcyclohexyl acrylate, trimethylcyclohexyl acrylate, tert-butylcyclohexyl acrylate, α-ethoxycyclohexyl acrylate, and the like.

[0069] Examples of the alkyl methacrylate having a homopolymer Tg of less than 30°C include linear or branched alkyl methacrylates having an alkyl group with approximately 4 to 12 carbon atoms, such as n-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, isohexyl methacrylate, n-heptyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, n-nonyl methacrylate, isononyl methacrylate, n-decyl methacrylate, and n-dodecyl methacrylate. These alkyl methacrylates may be used alone or in combination of two or more.

[0070] As the alkyl (meth)acrylate having a substituent, for example, there can be mentioned: an alkyl (meth)acrylate in which a substituent (a hydrogen atom of the alkyl group is substituted by a substituent) is introduced into the alkyl group in the alkyl (meth)acrylate. As such a substituent, for example, it can be an aryl group (such as a phenyl group), an aryloxy group (a phenoxy group), an alkoxy group (for example, a methoxy group, an ethoxy group, etc.), etc. As the alkyl acrylate having a substituent, for example, there can be mentioned: an alkoxyalkyl acrylate (for example, 2-methoxyethyl acrylate, ethoxymethyl acrylate, etc.), an aryloxyalkyl acrylate (for example, phenoxyethyl acrylate, etc.), an aryloxypolyalkylene glycol monoacrylate, a polyalkylene glycol monoacrylate, etc. These alkyl acrylates can be used alone or in combination of two or more. By including an alkyl acrylate containing an aromatic ring such as an aryl group or an aryloxy group, the white defect (Japanese original text: 白抜け) of the polarizing plate during the durability test can be improved. In addition, the alkylene group of the aryloxypolyalkylene glycol monoacrylate and the polyalkylene glycol monoacrylate can be, for example, a C1-C6 alkylene group such as a methylene group, an ethylene group, a propylene group (preferably an ethylene group, etc.), etc. From the viewpoint of the durability of the adhesive layer formed from the adhesive composition, the repeating unit of the oxyalkylene group can be, for example, 2 to 7, preferably 2 to 5 (especially 2). Specifically, for example, there can be mentioned: phenoxydiethylene glycol acrylate and other phenoxydi- to hepta-C1-C3 alkylene glycol monacrylates, diethylene glycol monacrylate and other di- to hepta-C1-C3 alkylene glycol monacrylates, etc.

[0071] As the monomer having a polar functional group other than a hydroxyl group, there can be mentioned (meth)acrylates having a substituent such as a heterocyclic group having a substituted or unsubstituted amino group, an epoxy group, etc. Specifically, there can be mentioned monomers having a heterocyclic group such as acryloylmorpholine, vinylcaprolactam, N-vinyl-2-pyrrolidone, vinylpyridine, (meth)acrylic acid tetrahydrofurfuryl ester, caprolactone-modified (meth)acrylic acid tetrahydrofurfuryl ester, (meth)acrylic acid 3,4-epoxycyclohexylmethyl ester, (meth)acrylic acid glycidyl ester, 2,5-dihydrofuran, etc.; monomers having a substituted or unsubstituted amino group such as (meth)acrylic acid aminoethyl ester, (meth)acrylic acid N,N-dimethylaminoethyl ester, (meth)acrylic acid dimethylaminopropyl ester, etc. These monomers can be used alone or in combination of two or more. It should be noted that, from the viewpoint of preventing the decrease in the peelability of the separator that can be laminated on the adhesive layer, it is preferably substantially free of a structural unit derived from a monomer having an amino group. It should be noted that substantially free means less than 1.0 part by mass relative to 100 parts by mass of all the structural units constituting the (meth)acrylic resin (A).

[0072] Examples of the (meth)acrylamide monomer include N-methylol (meth)acrylamide, N-(2-hydroxyethyl) (meth)acrylamide, N-(3-hydroxypropyl) (meth)acrylamide, N-(4-hydroxybutyl) (meth)acrylamide, N-(5-hydroxypentyl) (meth)acrylamide, N-(6-hydroxyhexyl) (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-isopropyl ...2-hydroxypropyl) (meth)acrylamide, N-(3-hydroxypropyl) (meth)acrylamide, N-(4-hydroxybutyl) (meth)acrylamide, N-(5-hydroxypentyl) (meth)acrylamide, N-(6-hydroxyhexyl) (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-(2-hydroxyethyl) (meth)acrylamide, N-isopropyl (meth)acrylamide, N-(2-hydroxyethyl) (meth)acrylamide, N-isopropyl (meth)acrylamide, N-isopropyl ) acrylamide, N-(3-dimethylaminopropyl)(meth)acrylamide, N-(1,1-dimethyl-3-oxobutyl)(meth)acrylamide, N-[2-(2-oxo-1-imidazolidinyl)ethyl](meth)acrylamide, 2-(meth)acryloylamino-2-methyl-1-propanesulfonic acid, N-(methoxymethyl)(meth)acrylamide, N-(ethoxymethyl)(meth)acrylamide, N-(propyloxymethyl)(meth)acrylamide, N-(1- Methylethoxymethyl)(meth)acrylamide, N-(1-methylpropoxymethyl)(meth)acrylamide, N-(2-methylpropoxymethyl)(meth)acrylamide [Also known as N-(isobutoxymethyl)(meth)acrylamide], N-(butoxymethyl)(meth)acrylamide, N-(1,1-dimethylethoxymethyl)(meth)acrylamide, N-(2-methoxyethyl)(meth)acrylamide, N-(2-ethoxyethyl)(meth)acrylamide, N-(2-propoxyethyl)(meth)acrylamide, N-[2-(1-methylethoxy)ethyl](meth)acrylamide, N-[2-(1-methylpropoxy)ethyl](meth)acrylamide, N-[2-(2-methylpropoxy)ethyl](meth)acrylamide [Also known as N-(2-isobutoxyethyl)acrylamide], N-(2-butoxyethyl)(meth)acrylamide, N-[2-(1,1-dimethylethoxy)ethyl](meth)acrylamide, etc. The structural unit derived from the (meth)acrylamide monomer may be used alone or in combination of two or more.

[0073] Examples of the styrene-based monomer include styrene; alkyl styrenes such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, and octylstyrene; halostyrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene; nitrostyrene; acetylstyrene; methoxystyrene; and divinylbenzene.

[0074] Examples of the vinyl monomer include: fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, and vinyl laurate; vinyl halides such as vinyl chloride and vinyl bromide; vinylidene halides such as vinylidene chloride; nitrogen-containing aromatic vinyls such as vinyl pyridine, vinyl pyrrolidone, and vinyl carbazole; and conjugated diene monomers such as butadiene, isoprene, and chloroprene.

[0075] Examples of monomers having multiple (meth)acryloyl groups in the molecule include: monomers having two (meth)acryloyl groups in the molecule, such as 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate; and monomers having three (meth)acryloyl groups in the molecule, such as trimethylolpropane tri(meth)acrylate.

[0076] From the viewpoint of easy reworkability and heat resistance and durability, the weight average molecular weight (Mw) of the (meth) acrylic resin (A) is preferably 1,000,000 or more and 3,200,000 or less, more preferably 1,100,000 to 3,100,000, further preferably 1,200,000 to 3,000,000, and particularly preferably 1,300,000 to 2,900,000. In addition, the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is usually 1.5 or more and 10 or less, preferably 2 or more and 5 or less, more preferably 2.5 or more and 4 or less. The weight average molecular weight can be analyzed by gel permeation chromatography and is a value converted to standard polystyrene.

[0077] From the viewpoint of mechanical strength and heat resistance durability, the glass transition temperature (Tg) of the (meth)acrylic resin (A) is preferably -45°C to -10°C, more preferably -40°C to -15°C, and even more preferably -38°C to -20°C.

[0078] A solution of the (meth)acrylic resin (A) (or a mixture thereof when two or more types are used) dissolved in ethyl acetate and adjusted to a concentration of 20% by mass preferably exhibits a viscosity of 20 Pa·s or less, more preferably 0.1 Pa·s to 7 Pa·s or less, at 25°C. The viscosity can be measured using a Brookfield viscometer.

[0079] (Meth)acrylic resin (A) can be produced by known methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. A polymerization initiator is generally used in the production of (meth)acrylic resin (A). The polymerization initiator is used in an amount of about 0.001 to 5 parts by mass relative to 100 parts by mass of all monomers used in the production of (meth)acrylic resin (A). Alternatively, (meth)acrylic resin (A) can be produced by a method in which polymerization is promoted using active energy rays such as ultraviolet rays.

[0080] As the polymerization initiator, a thermal polymerization initiator, a photopolymerization initiator, etc. can be used. Examples of the photopolymerization initiator include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone. Examples of the thermal polymerization initiator include: azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), and 2,2'-azobis(2-hydroxymethylpropionitrile); organic peroxides such as lauryl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, and (3,5,5-trimethylhexanoyl)peroxide; and inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide. Furthermore, a redox initiator using a peroxide and a reducing agent in combination can also be used as the polymerization initiator.

[0081] As a method for producing (meth)acrylic resin (A), among the methods shown above, solution polymerization is preferred. An example of a solution polymerization method is to mix a monomer and an organic solvent, add a thermal polymerization initiator under a nitrogen environment, and stir at about 40 to 90°C, preferably about 60 to 80°C for about 3 to 10 hours. In order to control the reaction, the monomer and the thermal polymerization initiator can be added continuously or intermittently during the polymerization, or added in a state dissolved in an organic solvent. As an organic solvent, for example, aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; aliphatic alcohols such as propanol and isopropanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone can be used.

[0082] (2) Cross-linking agent (B)

[0083] The adhesive composition further contains a crosslinking agent (B). The crosslinking agent (B) can be a compound that reacts with the structural unit of the (meth) acrylic resin (A), especially the monomer containing a polar functional group, and crosslinks the (meth) acrylic resin (A). Specifically, isocyanate compounds, epoxy compounds, aziridine compounds, metal chelate compounds, etc. can be exemplified. Among these, isocyanate compounds, epoxy compounds and aziridine compounds have at least two functional groups in the molecule that can react with the polar functional groups in the (meth) acrylic resin. The crosslinking agent (B) can be used alone or in combination of two or more.

[0084] The isocyanate compound is preferably a compound having at least two isocyanate groups (-NCO) in the molecule, and examples thereof include aliphatic isocyanate compounds (e.g., hexamethylene diisocyanate), alicyclic isocyanate compounds (e.g., isophorone diisocyanate), and aromatic isocyanate compounds (e.g., toluene diisocyanate, xylylenediisocyanate, hydrogenated xylylenediisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate). Furthermore, the crosslinking agent (B) may be an adduct of an isocyanate compound with a polyol compound (e.g., an adduct with glycerol, trimethylolpropane, etc.), or a derivative of a urethane prepolymer-type isocyanate compound obtained by an addition reaction with an isocyanurate, a biuret-type compound, a polyether polyol, a polyester polyol, an acrylic polyol, a polybutadiene polyol, or a polyisoprene polyol. The crosslinking agent (B) can be used alone or in combination of two or more. Representative examples of these include aromatic isocyanate compounds (e.g., toluene diisocyanate, xylylenediisocyanate), aliphatic isocyanate compounds (e.g., hexamethylene diisocyanate), or adducts thereof based on polyol compounds (glycerol, trimethylolpropane). When the crosslinking agent (B) contains an aromatic isocyanate compound and / or an adduct thereof based on a polyol compound, there is a tendency to improve reworkability and heat resistance and durability.

[0085] Epoxy compounds are compounds having at least two epoxy groups in the molecule. Specific examples include bisphenol A-type epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, N,N-diglycidyl aniline, N,N,N',N'-tetraglycidyl-m-xylenediamine, and 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane. Two or more epoxy compounds may be mixed and used.

[0086] Aziridine compounds, also known as ethyleneimines, are compounds containing at least two three-membered rings consisting of one nitrogen atom and two carbon atoms within the molecule. Specific examples include diphenylmethane-4,4'-bis(1-aziridinecarboxamide), toluene-2,4-bis(1-aziridinecarboxamide), triethylenemelamine, isophthaloylbis-1-(2-methylaziridine), tris-1-aziridinylphosphine oxide, hexamethylene-1,6-bis(1-aziridinecarboxamide), trimethylolpropane-tris-β-aziridinylpropionate, and tetramethylolmethane-tris-β-aziridinylpropionate.

[0087] Examples of the metal chelate compound include compounds in which acetylacetone or ethyl acetoacetate is coordinated to a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, or zirconium.

[0088] Among them, isocyanate compounds are preferred, and aromatic isocyanate compounds are more preferred, such as toluene diisocyanate, xylylenediisocyanate, hydrogenated xylylenediisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, and the like, and adducts thereof based on polyol compounds (e.g., glycerol, trimethylolpropane, etc.).

[0089] From the viewpoint of easy reworkability and heat resistance and durability, the content of the crosslinking agent (B) is preferably from 0.2 parts by mass to 5.0 parts by mass, and more preferably from 0.3 parts by mass to 2.0 parts by mass, relative to 100 parts by mass of the solid content of the (meth)acrylic resin (A) (or the total of the solid content when two or more types are used).

[0090] (3) Silane compound (C)

[0091] The silane compound (C) includes a silane compound represented by the following formula (i),

[0092] [Chemical Formula 3]

[0093]

[0094] [In formula (i),

[0095] A 1 represents an alkyl group having 1 to 5 carbon atoms,

[0096] A 2 and A 3 each independently represents an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms,

[0097] L represents an alkylene group having 8 to 20 carbon atoms or a group in which at least one methylene group constituting the alkylene group is replaced by a group selected from -NH- and -O-,

[0098] X represents an epoxy group or an alicyclic epoxy group. By containing the silane compound (C), the initial adhesive strength and the adhesive strength over time are reduced, and good adhesion to metals, transparent electrodes, glass substrates, etc. is exhibited in a high-temperature environment, thereby achieving both easy reworkability and heat resistance and durability.

[0099] In formula (i), as the compound that can constitute A 1 、A 2 and A 3 Examples of the alkyl group having 1 to 5 carbon atoms include methyl, ethyl, n- and isopropyl, n-, iso- and tert-butyl, and pentyl groups such as n-, iso- and tert-pentyl.

[0100] In formula (i), as the compound that can constitute A 2 and A 3 Examples of the alkoxy group having 1 to 5 carbon atoms include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, and various pentoxy groups such as n-, iso-, and tert-pentoxy.

[0101] In formula (i), examples of the alkylene group having 8 to 20 carbon atoms that can constitute L include: -(CH2) n -(wherein n represents an integer of 8 to 20).

[0102] When L is a group in which at least one methylene group constituting an alkylene group having 8 to 20 carbon atoms is replaced by a group selected from -NH- and -O-, only one methylene group may be replaced by -NH- or -O-, or two or more methylene groups may each be replaced by -NH- or -O-. When two or more methylene groups are replaced, typically, the two or more replaced -NH- and / or -O- groups are bonded via an alkylene group having 2 or more carbon atoms.

[0103] In formula (i), the epoxy group that can constitute X may be a group represented by the following formula.

[0104] [Chemical Formula 4]

[0105]

[0106] In formula (i), examples of the alicyclic epoxy group that can constitute X include monovalent groups obtained by removing one hydrogen atom from the structure represented by the following formula.

[0107] [Chemical Formula 5]

[0108]

[0109] (In the formula, n represents an integer from 1 to 5.)

[0110] Among them, from the viewpoint of improving the adhesion under high temperature environment, the silane compound (C) is preferably A 1 Methyl or ethyl, A 2 and A 3 Each of them is independently a methoxy group or an ethoxy group, X is an epoxy group, and more preferably contains or consists of a silane compound (C-1) represented by formula (C-1).

[0111] [Chemical Formula 6]

[0112]

[0113] In the above formula (C-1), m represents an integer of 6 to 18.

[0114] Specific examples of the silane compound (C-1) include:

[0115] 6-glycidoxyhexyltrimethoxysilane,

[0116] 7-glycidoxyheptyltrimethoxysilane,

[0117] 8-glycidoxyoctyltrimethoxysilane,

[0118] 9-glycidoxynonyltrimethoxysilane,

[0119] 10-glycidoxydecyltrimethoxysilane,

[0120] 11-glycidoxyundecyltrimethoxysilane,

[0121] 12-glycidoxydodecyltrimethoxysilane,

[0122] 13-glycidoxytridecyltrimethoxysilane,

[0123] 14-glycidoxytetradecyltrimethoxysilane,

[0124] 15-glycidoxypentadecyltrimethoxysilane,

[0125] 16-glycidoxyhexadecyltrimethoxysilane,

[0126] 17-glycidoxyheptadecyltrimethoxysilane,

[0127] 18-Glycidoxyoctadecyltrimethoxysilane. The silane compound (C-1) is often a liquid. A commercially available product or a silane compound produced by a known method may be used as the silane compound (C-1).

[0128] From the viewpoint of easy reworkability and heat resistance and durability, the content of the silane compound (C) in the adhesive composition is preferably from 0.01 to 2 parts by mass, more preferably from 0.1 to 1.8 parts by mass, relative to 100 parts by mass of the solid content of the (meth)acrylic resin (A) (if two or more are used, the total of these). If the content is below the upper limit, it is beneficial to suppress the exudation of the silane compound (C) from the adhesive layer. If it is above the lower limit, it is easy to improve the adhesion (or bonding) between the adhesive layer and the metal layer, glass substrate, etc., which is beneficial to improve the peeling resistance.

[0129] (4) Ionic compounds

[0130] The adhesive composition may further contain an ionic compound. The ionic compound can function as an antistatic agent for imparting antistatic properties to the adhesive layer. An ionic compound is a compound having an inorganic cation or an organic cation and an inorganic anion or an organic anion.

[0131] Examples of inorganic cations include lithium cations [Li + ]、Sodium cation [Na + ]、potassium cation [K + ] and other alkali metal ions; beryllium cations [Be 2+ ]、Mg cation [Mg 2+ ]、Calcium cation [Ca 2+ ] and other alkaline earth metal ions, etc.

[0132] Examples of the organic cation include an imidazolium cation, a pyridinium cation, a pyrrolidinium cation, an ammonium cation, a sulfonium cation, and a phosphonium cation.

[0133] Among the above cationic components, organic cationic components are preferably used due to their excellent compatibility with the adhesive composition. Among organic cationic components, pyridinium cations and imidazolium cations are particularly preferred because they are less likely to be charged when a release film provided on the adhesive layer is peeled off.

[0134] Examples of inorganic anions include chloride anions [Cl - ]、bromine anion [Br - ]、iodide anion [I - ]、tetrachloroaluminate anion [AlCl4 - ]、heptachlorodialuminate anion [Al2Cl7 - ], tetrafluoroborate anion [BF4 - ], hexafluorophosphate anion [PF6 - ]、perchlorate anion [ClO4 - ]、nitrate anion [NO3- ], hexafluoroarsenate anion [AsF6 - ], hexafluoroantimonate anion [SbF6 - ], hexafluoroniobate anion [NbF6 - ]、hexafluorotantalate anion [TaF6 - ], dicyanimide anion [(CN)2N - ]wait.

[0135] Examples of organic anions include acetate anions [CH3COO - ], trifluoroacetate anion [CF3COO - ], methanesulfonate anion [CH3SO3 - ], trifluoromethanesulfonate anion [CF3SO3 - ], p-toluenesulfonate anion [p-CH3C6H4SO3 - ]、bis(fluorosulfonyl)imide anion [(FSO2)2N - ]、bis(trifluoromethanesulfonyl)imide anion [(CF3SO2)2N - ], tris(trifluoromethanesulfonyl)methanide anion [(CF3SO2)3C - ], dimethylphosphonate anion [(CH3)2POO - ]、(Poly)hydrogen fluoride anion [F(HF) n - ] (n is about 1 to 3), thiocyanate anion [SCN - ]、perfluorobutanesulfonate anion [C4F9SO3 - ]、bis(pentafluoroethanesulfonyl)imide anion [(C2F5SO2)2N - ]、perfluorobutyrate anion [C3F7COO - ]、(trifluoromethanesulfonyl)(trifluoromethanecarbonyl)imide anion [(CF3SO2)(CF3CO)N - ]、perfluoropropane-1,3-disulfonate anion[ - O3S(CF2)3SO3 - ]、carbonate anion [CO3 2- ]wait.

[0136] Among the above-mentioned anionic components, particularly those containing fluorine atoms can form ionic compounds with excellent antistatic properties and are therefore preferably used. Examples of the anionic components containing fluorine atoms include bis(fluorosulfonyl)imide anions, hexafluorophosphate anions, and bis(trifluoromethanesulfonyl)imide anions.

[0137] Specific examples of the ionic compound can be appropriately selected from the above-mentioned combinations of cationic components and anionic components. Examples of ionic compounds having organic cations, when classified and disclosed according to the structure of the organic cation, include the following compounds.

[0138] Pyridinium salts:

[0139] N-hexylpyridinium hexafluorophosphate,

[0140] N-octylpyridinium hexafluorophosphate,

[0141] N-octyl-4-methylpyridinium hexafluorophosphate,

[0142] N-butyl-4-methylpyridinium hexafluorophosphate,

[0143] Tetrabutylammonium hexafluorophosphate,

[0144] N-decylpyridinium bis(fluorosulfonyl)imide,

[0145] N-dodecylpyridinium bis(fluorosulfonyl)imide,

[0146] N-tetradecylpyridinium bis(fluorosulfonyl)imide,

[0147] N-hexadecylpyridinium bis(fluorosulfonyl)imide,

[0148] N-dodecyl-4-methylpyridinium bis(fluorosulfonyl)imide,

[0149] N-tetradecyl-4-methylpyridinium bis(fluorosulfonyl)imide,

[0150] N-hexadecyl-4-methylpyridinium bis(fluorosulfonyl)imide,

[0151] N-benzyl-2-methylpyridinium bis(fluorosulfonyl)imide,

[0152] N-benzyl-4-methylpyridinium bis(fluorosulfonyl)imide,

[0153] N-hexylpyridinium bis(trifluoromethanesulfonyl)imide,

[0154] N-octylpyridinium bis(trifluoromethanesulfonyl)imide,

[0155] N-octyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide,

[0156] N-Butyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide.

[0157] Imidazolium salts:

[0158] 1-ethyl-3-methylimidazolium hexafluorophosphate,

[0159] 1-ethyl-3-methylimidazolium p-toluenesulfonate,

[0160] 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide,

[0161] 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide,

[0162] 1-Butyl-3-methylimidazolium methanesulfonate,

[0163] 1-Butyl-3-methylimidazolium bis(fluorosulfonyl)imide.

[0164] Pyrrolidinium salts:

[0165] N-butyl-N-methylpyrrolidinium hexafluorophosphate,

[0166] N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide,

[0167] N-Butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide.

[0168] Quaternary ammonium salts:

[0169] Tetrabutylammonium p-toluenesulfonate,

[0170] (2-Hydroxyethyl)trimethylammonium bis(trifluoromethanesulfonyl)imide,

[0171] (2-Hydroxyethyl)trimethylammonium dimethylphosphinate,

[0172] Tributylmethylammonium bis(trifluoromethanesulfonyl)imide,

[0173] Trimethylpropylammonium bis(trifluoromethanesulfonyl)imide,

[0174] Methyltri-n-octylammonium bis(trifluoromethanesulfonyl)imide.

[0175] Furthermore, examples of ionic compounds having inorganic cations include the following compounds.

[0176] lithium bromide,

[0177] lithium iodide,

[0178] lithium tetrafluoroborate,

[0179] Lithium hexafluorophosphate,

[0180] lithium thiocyanate,

[0181] lithium perchlorate,

[0182] Lithium trifluoromethanesulfonate,

[0183] Lithium bis(fluorosulfonyl)imide,

[0184] Lithium bis(trifluoromethanesulfonyl)imide,

[0185] Lithium bis(pentafluoroethanesulfonyl)imide,

[0186] lithium tris(trifluoromethanesulfonyl)methanide,

[0187] Lithium p-toluenesulfonate,

[0188] Sodium hexafluorophosphate,

[0189] Sodium bis(fluorosulfonyl)imide,

[0190] Sodium bis(trifluoromethanesulfonyl)imide,

[0191] Sodium p-toluenesulfonate,

[0192] Potassium hexafluorophosphate,

[0193] Potassium bis(fluorosulfonyl)imide,

[0194] Potassium bis(trifluoromethanesulfonyl)imide,

[0195] Potassium p-toluenesulfonate.

[0196] The ionic compound is preferably solid at room temperature. Compared to the case of using an ionic compound that is liquid at room temperature, the antistatic performance can be maintained for a long time. From the perspective of long-term stability of such antistatic properties, the ionic compound preferably has a melting point of 25°C or higher. On the other hand, if its melting point is too high, the compatibility with the (meth)acrylic resin (A) will deteriorate. Therefore, the melting point is preferably 90°C or lower, more preferably 70°C or lower, and even more preferably less than 50°C.

[0197] The content of the ionic compound in the adhesive composition is generally 0.2 to 10 parts by mass relative to 100 parts by mass of the solid content of the (meth)acrylic resin (A) (or the total of these when two or more types are used). From the perspectives of reworkability and heat resistance and durability, it is preferably 0.3 to 9 parts by mass, and more preferably 0.5 to 8 parts by mass. Within this range, the ionic compound is less likely to aggregate in the adhesive, thereby improving heat resistance and durability.

[0198] (5) Other ingredients

[0199] The adhesive composition may contain additives such as a solvent, a crosslinking catalyst, an ultraviolet light absorber, a weathering stabilizer, a tackifier, a plasticizer, a softener, a dye, a pigment, an inorganic filler, light scattering particles, a rust preventer, a stripping agent, and resins other than the (meth) acrylic resin (A). In addition, it is also useful to coordinate an ultraviolet curable compound in the adhesive composition, form an adhesive layer, and then irradiate it with ultraviolet light to cure it, thereby making a harder adhesive layer. As a crosslinking catalyst, for example, amine compounds such as hexamethylenediamine, ethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, trimethylenediamine, polyamino resins, and melamine resins can be mentioned.

[0200] When the adhesive composition contains a crosslinking agent (B) and also contains a crosslinking catalyst, the adhesive layer can be prepared by aging in a short time. In addition, if a crosslinking catalyst is contained, the bulging, peeling, and foaming of the adhesive layer at the interface of the adhesive layer and the parts adjacent thereto can be more effectively suppressed, and reworkability (reworkability) is also improved. As a crosslinking catalyst, for example, amine compounds such as hexamethylenediamine, ethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, trimethylenediamine, polyamino resins and melamine resins can be mentioned. When the adhesive composition is combined with an amine compound as a crosslinking catalyst, an isocyanate compound is suitable as a crosslinking agent (B).

[0201] The adhesive composition can be prepared by mixing the above components. The gel fraction of the adhesive composition can be, for example, 50% to 98%, preferably 60% to 95%. The gel fraction can be measured according to the measurement method described in the Examples section below.

[0202] The adhesive composition may exhibit little or no changes in appearance, such as swelling, peeling, cracking, or foaming, during a heat resistance durability test, preferably no such changes. Furthermore, the adhesive composition may exhibit excellent reworkability. The heat resistance durability test and reworkability evaluation may be performed according to the methods described in the Examples section below.

[0203] <Adhesive Layer>

[0204] The adhesive layer of the present invention comprises, and typically consists of, the adhesive composition of the present invention. The adhesive layer can be formed by dissolving or dispersing the components of the adhesive composition in a solvent to form a solvent-containing adhesive composition, then applying the solvent-containing adhesive composition onto a substrate film and drying the resulting composition. The adhesive layer exhibits excellent reworkability, heat resistance, and durability.

[0205] The substrate film is generally a plastic film, and as a typical example, a release film (separator) having been subjected to a demoulding process can be cited. The release film can be, for example, a film having been subjected to a demoulding process such as silicone treatment on the adhesive layer-forming surface of a film formed from various resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, and polyarylate. In addition, an adhesive layer can be formed by directly applying an adhesive composition to the surface of an optical component, and a release film can be laminated on the outer surface of the adhesive layer as needed to form an optical component with an adhesive layer. When the adhesive layer is provided on the surface of the optical component, surface activation treatment can be implemented on the bonding surface of the optical component and / or the bonding surface of the adhesive layer, such as plasma treatment, corona treatment, etc., as needed.

[0206] The thickness of the adhesive layer can be, for example, 10 μm to 50 μm, and is preferably 15 μm to 40 μm, and more preferably 18 μm to 35 μm, from the viewpoint of reworkability and heat resistance and durability.

[0207] The initial adhesion of the adhesive layer can be, for example, 5.0 N / 25 mm or less, preferably 4.0 N / 25 mm or less, more preferably 3.0 N / 25 mm or less, and usually 0.5 N / 25 mm or more. The initial adhesion can be measured by the method described in the Examples section below.

[0208] From the perspective of ease of reworkability, the adhesive strength of the adhesive layer over time is preferably 9.9 N / 25 mm or less, more preferably 7.0 N / 25 mm or less, further preferably 5.0 N / 25 mm or less, and usually 0.5 N / 25 mm or more. The adhesive strength over time can be measured according to the method described in the Examples section below.

[0209] From the viewpoint of reworkability, the difference between the initial adhesion and the adhesion over time of the adhesive layer is preferably 3.9 N / 25 mm or less, more preferably 3.0 N / 25 mm or less, and even more preferably 2.0 N / 25 mm or less.

[0210] <Optical Film with Adhesive Layer>

[0211] The pressure-sensitive adhesive layer-carrying optical film of the present invention may include, for example, an optical film and the pressure-sensitive adhesive layer laminated thereon.

[0212] Examples of the optical film include: a polarizer; a protective film provided to protect the surface of a polarizer, etc.; a polarizing plate having a protective film laminated on one or both sides of a polarizer; a phase difference film; an optical compensation film other than a phase difference film; a film having an anti-glare function with a concave-convex surface, a film having an anti-reflection function on the surface; a reflective film having a reflective function on the surface; a semi-transmissive reflective film having both a reflective function and a transmissive function; a light diffusion film; a hard coating film, etc. The optical film with an adhesive layer may include one or more optical films, or may include two or more optical films of the same type. When two or more optical films are included, a bonding layer described below may be used to laminate two or more optical films. In this case, the bonding layer may also become part of the optical film. The thickness of the optical film is not particularly limited, and for example, it may be set to be greater than 5 μm and less than 300 μm. In this specification, a polarizing plate having a protective film laminated on one or both sides of a polarizer is also referred to as a linear polarizing plate.

[0213] Examples of the polarizing plate include a polarizing plate in which iodine is oriented in a polyvinyl alcohol-based resin layer and a polarizing plate in which a liquid crystal compound and a dichroic dye are oriented.

[0214] The protective film is not particularly limited, but is preferably a light-transmitting (preferably optically transparent) thermoplastic resin film. Examples of thermoplastic resins constituting such a film include: polyolefin resins such as chain polyolefin resins (polyethylene resins, polypropylene resins, etc.) and cyclic polyolefin resins (norbornene resins, etc.); cellulose ester resins such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polycarbonate resins; (meth)acrylic acid resins such as (meth)acrylic acid and polymethyl (meth)acrylate; vinyl alcohol resins such as polyvinyl alcohol and polyvinyl acetate; polystyrene resins; and mixtures and copolymers thereof. It should be noted that, in this specification, "(meth)acrylic acid" means "at least one of acrylic acid and methacrylic acid." These resins may contain one or more of the following additives: lubricants, plasticizers, dispersants, heat stabilizers, ultraviolet absorbers, infrared absorbers, antistatic agents, antioxidants, light diffusing agents such as fine particles.

[0215] Examples of the chain polyolefin-based resin include homopolymers of chain olefins such as polyethylene resin and polypropylene resin, and copolymers composed of two or more chain olefins.

[0216] Cyclic polyolefin resins are a general term for resins polymerized using cyclic olefins as polymerized units. Specific examples of cyclic polyolefin resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers (typically random copolymers) of cyclic olefins with chain olefins such as ethylene and propylene, graft polymers of these modified with unsaturated carboxylic acids or their derivatives, and hydrogenated forms thereof. Of these, norbornene resins using norbornene monomers such as norbornene and polycyclic norbornene monomers as cyclic olefins are preferred.

[0217] The cellulose resin is a partially or completely esterified product of cellulose, and examples thereof include cellulose acetate, propionate, butyrate, and mixed esters thereof. Among them, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate are preferably used.

[0218] Polyester resins are resins other than the above-mentioned cellulose resins that have ester bonds and are generally formed from condensation products of polycarboxylic acids or their derivatives with polyols. Examples of polycarboxylic acids or their derivatives include dicarboxylic acids or their derivatives, such as terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalate. Examples of polyols include diols, such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, and cyclohexanedimethanol.

[0219] Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexane dimethyl terephthalate, and polycyclohexane dimethyl naphthalate.

[0220] Polycarbonate resins include polymers in which monomer units are bonded via carbonate groups. Polycarbonate resins may be resins called modified polycarbonates in which the polymer skeleton is modified, or copolymerized polycarbonates.

[0221] The (meth)acrylic resin may be a polymer containing methacrylate as a main monomer, preferably a copolymer containing a small amount of other comonomers. The (meth)acrylic resin is more preferably a copolymer of methyl methacrylate and methyl acrylate, and may further contain a third monofunctional monomer.

[0222] Examples of the third monofunctional monomer include: methacrylic acid esters other than methyl methacrylate, such as ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl methacrylate; acrylic acid esters, such as ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate; hydroxyalkyl acrylates, such as methyl 2-(hydroxymethyl)acrylate, methyl 2-(1-hydroxyethyl)acrylate, ethyl 2-(hydroxymethyl)acrylate, and butyl 2-(hydroxymethyl)acrylate; unsaturated acids, such as methacrylic acid and acrylic acid; halostyrenes, such as chlorostyrene and bromostyrene; substituted styrenes, such as vinyltoluene and α-methylstyrene; unsaturated nitriles, such as acrylonitrile and methacrylonitrile; unsaturated acid anhydrides, such as maleic anhydride and citraconic anhydride; and unsaturated imides, such as phenylmaleimide and cyclohexylmaleimide. The third monofunctional monomer may be used alone or in combination of two or more.

[0223] In the (meth)acrylic resin, a multifunctional monomer may be further copolymerized. Examples of the multifunctional monomer include: monomers obtained by esterifying the terminal hydroxyl groups of ethylene glycol or its oligomers with acrylic acid or methacrylic acid, such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, and tetradecaethylene glycol di(meth)acrylate; monomers obtained by esterifying the terminal hydroxyl groups of propylene glycol or its oligomers with acrylic acid or methacrylic acid; monomers obtained by esterifying the hydroxyl groups of diols with acrylic acid or methacrylic acid, such as neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate, and butanediol di(meth)acrylate; and bisphenol A. A monomer obtained by esterifying both terminal hydroxyl groups of bisphenol A and alkylene oxide adducts of bisphenol A, or esterifying both terminal hydroxyl groups of these halogen-substituted products with acrylic acid or methacrylic acid; a monomer obtained by esterifying a polyol such as trimethylolpropane or pentaerythritol with acrylic acid or methacrylic acid, and a monomer obtained by ring-opening addition of the epoxy group of glycidyl acrylate or glycidyl methacrylate to these terminal hydroxyl groups; a monomer obtained by ring-opening addition of the epoxy group of glycidyl acrylate or glycidyl methacrylate to dibasic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, or their halogen-substituted products, or alkylene oxide adducts thereof; aryl (meth)acrylates; aromatic divinyl compounds such as divinylbenzene, etc. Among these, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferably used.

[0224] The (meth)acrylic resin may be modified by further reacting the functional groups of the copolymer. Examples of such reactions include intramolecular decarbinolation condensation between the methyl ester group of methyl acrylate and the hydroxyl group of methyl 2-(hydroxymethyl)acrylate, and intramolecular dehydration condensation between the carboxyl group of acrylic acid and the hydroxyl group of methyl 2-(hydroxymethyl)acrylate. Furthermore, the (meth)acrylic resin may optionally have a glutarimide derivative, a glutaric anhydride derivative, or a lactone ring structure.

[0225] The glass transition temperature of the (meth)acrylic resin is preferably 90 to 160°C, more preferably 110 to 160°C, and even more preferably 120 to 150°C.

[0226] The (meth)acrylic resin may contain additives as needed. Examples of the additives include lubricants, antiblocking agents, heat stabilizers, antioxidants, antistatic agents, light stabilizers, impact resistance improvers, and surfactants.

[0227] From the viewpoint of film-forming properties and impact resistance of the film, the (meth)acrylic resin may contain acrylic rubber particles as an impact modifier. Acrylic rubber particles refer to particles having an elastic polymer mainly composed of acrylic ester as an essential component. Examples include particles having a single-layer structure consisting essentially of the elastic polymer and particles having a multilayer structure in which the elastic polymer is a single layer. Examples of such elastic polymers include cross-linked elastic copolymers obtained by copolymerizing an alkyl acrylate as a main component and the alkyl acrylate with other vinyl monomers copolymerizable therewith and a cross-linking monomer. Examples of the alkyl acrylate that is the main component of the elastic polymer include alkyl acrylates having an alkyl group carbon number of about 1 to 8, such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. In particular, acrylic acid having an alkyl group carbon number of 4 or more is preferably used. Examples of other vinyl monomers copolymerizable with the alkyl acrylate include compounds having one polymerizable carbon-carbon double bond in the molecule, more specifically methacrylates such as methyl methacrylate, aromatic vinyl compounds such as styrene, and vinyl cyanide compounds such as acrylonitrile. Examples of crosslinking monomers include crosslinking compounds having at least two polymerizable carbon-carbon double bonds in the molecule, more specifically (meth)acrylates of polyols such as ethylene glycol di(meth)acrylate and butanediol di(meth)acrylate; alkenes of (meth)acrylic acid such as allyl (meth)acrylate; and divinylbenzene.

[0228] A laminate of a film formed of an acrylic resin not containing rubber particles and a film formed of an acrylic resin containing rubber particles can be used as the protective film.

[0229] Phase difference film is an optical film showing optical anisotropy, which can be: a stretched film obtained by stretching a resin film formed by a resin that can be used for the above-mentioned protective film, such as a polyvinyl alcohol resin, a polyarylate resin, a polyimide resin, a polyethersulfone resin, a polyvinylidene fluoride / polymethyl methacrylate resin, a liquid crystal polyester resin, an ethylene-vinyl acetate copolymer saponified product, a polyvinyl chloride resin, etc. to about 1.01 to 6 times. Among them, it is preferred to stretch a polycarbonate resin film, a cycloolefin resin film, a (meth) acrylic resin film or a cellulose resin film by uniaxial stretching or biaxial stretching. In addition, in this specification, a zero delay film is also included in the phase difference film (however, it can also be used as a protective film). In addition, films such as uniaxial phase difference film, wide viewing angle phase difference film, low photoelastic modulus phase difference film, etc. can also be used as phase difference film.

[0230] The retardation film may be a film having an optically anisotropic layer formed of a polymer polymerized in an aligned state of a polymerizable liquid crystal compound on a substrate. The substrate may be the thermoplastic resin film used for the protective film.

[0231] The retardation film may be, for example, a quarter-wave retardation layer with reverse wavelength dispersion, a positive C plate, a half-wave retardation layer with positive wavelength dispersion, or a quarter-wave retardation layer with positive wavelength dispersion. The retardation film may be composed of two or more retardation layers, for example, a structure combining a quarter-wave retardation layer with reverse wavelength dispersion and a positive C plate, or a structure combining a half-wave retardation layer with positive wavelength dispersion and a quarter-wave retardation layer with positive wavelength dispersion.

[0232] The moisture permeability of the retardation film and the protective film measured by the cup method specified in JIS Z 0208 at a temperature of 40°C and a relative humidity of 90% can be 500g / (m 2 ·24hr) or less.

[0233] A surface protective film is a film used to protect the surface of an optical film or the like from damage or contamination. For example, various optical films such as polarizers, protective films, phase difference films, light diffusers, and reflective sheets used in liquid crystal displays are typically distributed with the surface protective film attached to their surface (if one side has an adhesive layer, the surface opposite to the adhesive layer). The surface protective film is typically removed by peeling after the optical film is attached to a liquid crystal cell or the like.

[0234] Examples of the substrate of the surface protective film include: polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; fluorinated polyolefin resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyethylene fluoride; polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate / isophthalate copolymer; polyamides such as nylon 6 and nylon 6,6; vinyl polymers such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, and vinylon; cellulose resins such as triacetyl cellulose, diacetyl cellulose, and cellophane; (meth)acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate; and polystyrene, polycarbonate, polyarylate, and polyimide.

[0235] The laminating layer can be an adhesive layer or an adhesive layer. When the laminating layer is an adhesive layer, the laminating layer can use an adhesive layer other than the above-mentioned adhesive layer. When the laminating layer is an adhesive layer, the adhesive layer can be composed of an adhesive composition with resins such as (methyl) acrylic resin, rubber resin, urethane resin, ester resin, silicone resin, polyvinyl ether resin as main components. Wherein, an adhesive composition with an excellent (methyl) acrylic resin such as transparency, weather resistance, heat resistance as matrix polymer is suitable. The adhesive composition can be active energy ray curing type or thermosetting type.

[0236] As the (meth)acrylic resin (base polymer) used in the adhesive composition, a polymer or copolymer containing one or more (meth)acrylates such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate as monomers is preferably used. The base polymer is preferably a copolymer of a polar monomer. Examples of polar monomers include monomers having carboxyl groups, hydroxyl groups, amide groups, amino groups, and epoxy groups, such as (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate.

[0237] The adhesive composition may consist solely of the aforementioned base polymer, but typically further contains a crosslinking agent. Examples of crosslinking agents include: divalent or higher-valent metal ions, which form metal carboxylates with carboxyl groups; polyamine compounds, which form amide bonds with carboxyl groups; polyepoxides and polyols, which form ester bonds with carboxyl groups; and polyisocyanate compounds, which form amide bonds with carboxyl groups. Polyisocyanate compounds are preferred.

[0238] When the bonding layer is an adhesive layer, the thickness of the bonding layer is preferably 1 μm to 200 μm, more preferably 2 μm to 100 μm, further preferably 2 μm to 80 μm, and particularly preferably 3 μm to 50 μm.

[0239] When the lamination layer is an adhesive layer, any appropriate adhesive can be used as the adhesive, and examples of the adhesive that can be used include water-based adhesives and active energy ray-curable adhesives.

[0240] The thickness of the adhesive during application can be set to any appropriate value. For example, it can be set so that an adhesive layer having a desired thickness can be obtained after curing or heating (drying). The thickness of the adhesive layer is preferably 0.01 μm or more and 7 μm or less, more preferably 0.01 μm or more and 5 μm or less, further preferably 0.01 μm or more and 2 μm or less, and most preferably 0.01 μm or more and 1 μm or less.

[0241] Examples of the water-based adhesive include a polyvinyl alcohol-based resin aqueous solution and a water-based two-component urethane emulsion adhesive.

[0242] The active energy ray-curable adhesive is an adhesive containing a curable compound that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays, and is preferably an ultraviolet-curable adhesive.

[0243] The above-mentioned curable compound may be a cationically polymerizable curable compound or a radically polymerizable curable compound. Examples of cationically polymerizable curable compounds include epoxy compounds (compounds having one or more epoxy groups in the molecule), oxetane compounds (compounds having one or more oxetane rings in the molecule), or combinations thereof. Examples of radically polymerizable curable compounds include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule), other vinyl compounds having radically polymerizable double bonds, or combinations thereof. A cationically polymerizable curable compound and a radically polymerizable curable compound may also be used in combination. The active energy ray-curable adhesive generally further comprises: at least one of a cationic polymerization initiator and a radical polymerization initiator for initiating the curing reaction of the above-mentioned curable compound.

[0244] In order to improve the adhesion, a surface activation treatment may be implemented on the bonding surface of at least one of the bonding layer and the optical film. Examples of surface activation treatments include dry treatments such as corona treatment, plasma treatment, discharge treatment (glow discharge treatment, etc.), ozone treatment, UV ozone treatment, ionizing active ray treatment (ultraviolet treatment, electron beam treatment, etc.). These surface activation treatments may be performed alone or in combination of two or more. Corona treatment is preferred. Corona treatment may be performed at a rate of, for example, 1 kJ / m 2 Above and 50kJ / m 2 The following output is performed. The time for performing the corona treatment can be, for example, 1 second or longer and 1 minute or shorter.

[0245] In the optical film with an adhesive layer of this embodiment, the release film is preferably attached to the surface of the adhesive layer to protect it before use. The optical film with an adhesive layer of this embodiment with a release film attached can be produced by the following methods: a method of coating an adhesive composition on a release film to form an adhesive layer, and further laminating a resin film on the resulting adhesive layer; or a method of coating an adhesive composition on a resin film to form an adhesive layer, and laminating a release film on the adhesive surface.

[0246] The optical film with a pressure-sensitive adhesive layer can be used in display devices such as organic electroluminescent (organic EL) display devices and liquid crystal display devices, and can be bonded to the viewing side of the image display element of the display device.

[0247] The optical film with a pressure-sensitive adhesive layer has no particular limitation on its laminated structure as long as it includes an optical film and a pressure-sensitive adhesive layer laminated on the optical film.

[0248] Figure 1 The illustrated optical film with a pressure-sensitive adhesive layer 10 includes a linear polarizing plate 11 and a pressure-sensitive adhesive layer 12. The linear polarizing plate 11 includes, in this order, a first protective film 13, an adhesive layer 14, a polarizer 15, an adhesive layer 16, and a second protective film 17. The pressure-sensitive adhesive layer 12 can be bonded to a liquid crystal cell, which serves as an image display element, in a liquid crystal display device. A separator (release film) (not shown) may be provided on the surface of the pressure-sensitive adhesive layer 12 opposite the linear polarizing plate 11.

[0249] Figure 2 The illustrated optical film 20 with an adhesive layer includes, in order, an adhesive layer 21, a retardation film 22, a laminating layer 23, and a linear polarizing plate 24. The linear polarizing plate 24 includes, in order, a first protective film 25, an adhesive layer 26, a polarizer 27, an adhesive layer 28, and a second protective film 29. The adhesive layer 21 can be laminated to a liquid crystal cell, which serves as an image display element of a liquid crystal display device. A separator (release film) (not shown) may be provided on the surface of the adhesive layer 21 opposite the retardation film 22.

[0250] Figure 1and Figure 2 The optical films 10 and 20 with adhesive layers shown are merely examples, and may also have a laminated structure other than the above. For example, the protective film may have another layer such as a hard coat film, a film with an anti-glare function, or a film with an anti-surface reflection function.

[0251] <Display device>

[0252] The display device of the present invention comprises the above-mentioned optical film with an adhesive layer. The above-mentioned optical film with an adhesive layer can be applied to display devices such as organic EL display devices, liquid crystal display devices, inorganic electroluminescent (inorganic EL) display devices, and electron emission display devices.

[0253] Figure 3 The display device 30 shown includes Figure 1 The optical film 10 with a pressure-sensitive adhesive layer and a liquid crystal display device with a liquid crystal display element 31 are shown. The optical film 10 with a pressure-sensitive adhesive layer can be disposed on the viewing side and / or the back side of the liquid crystal display element 31 via the pressure-sensitive adhesive layer 12.

[0254] Example

[0255] The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Hereinafter, "parts" and "%" indicating the amount or content are by mass unless otherwise specified.

[0256] <Manufacturing Example 1: Manufacture of (meth)acrylic resin for adhesive layer>

[0257] A mixed solution of 86.4 parts ethyl acetate, 68.7 parts butyl acrylate, 20.0 parts methyl acrylate, 10.0 parts methyl methacrylate, 1.0 part 2-hydroxyethyl acrylate, and 0.3 parts acrylic acid was added to a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer. While replacing the air in the vessel with nitrogen to create an oxygen-free state, the internal temperature was raised to 60°C. A solution of 0.15 parts azobisisobutyronitrile (polymerization initiator) dissolved in 13.7 parts ethyl acetate was then added to the entire mixture. After adding the initiator, this concentration was maintained for 4 hours. Finally, ethyl acetate was added to adjust the concentration of the (meth)acrylic resin to 20% by mass, thereby preparing an ethyl acetate solution of the (meth)acrylic resin.

[0258] The glass transition temperature (Tg) of the obtained (meth)acrylic resin was measured.

[0259] Tg was measured using a differential scanning calorimeter (DSC) "EXSTARDSC6000" manufactured by SII NanoTechnology Co., Ltd. under a nitrogen atmosphere at a measurement temperature range of -80 to 50°C and a heating rate of 10°C / min.

[0260] The weight average molecular weight (Mw) and number average molecular weight (Mn) of the obtained (meth)acrylic resin were measured.

[0261] Mw and Mn were measured by converting to standard polystyrene using tetrahydrofuran as the eluent, using one "TSKgel guardcolumn HHR-H(S)" and two "TSKgel GMHHR-H" manufactured by Tosoh Corporation as columns, which were connected in series in a GPC apparatus. The conditions were sample concentration of 2 mg / mL, sample introduction volume of 100 μL, temperature of 40°C, and flow rate of 1 mL / min.

[0262] Table 1 summarizes the monomer composition of the monomer mixture used, and Tg, Mw, and molecular weight distribution (Mw / Mn) of the obtained (meth)acrylic resin.

[0263] <Production Examples 2 to 8>

[0264] Except having made the monomer composition into what is shown in Table 1, it carried out similarly to Production Example 1, and prepared the ethyl acetate solution of (meth)acrylic-type resin.

[0265] [Table 1]

[0266]

[0267] The abbreviations in the "Monomer composition" column of Table 1 mean the following monomers.

[0268] BA: Butyl acrylate (homopolymer Tg: -54°C)

[0269] OA: Octyl methacrylate (homopolymer Tg: -65°C)

[0270] MA: Methyl acrylate (homopolymer Tg: 10°C)

[0271] MMA: Methyl methacrylate (homopolymer Tg: 105°C)

[0272] IBMA: Isobornyl methacrylate (homopolymer Tg: 110°C)

[0273] TBMA: tert-butyl methacrylate (homopolymer Tg: 118°C)

[0274] CHMA: Cyclohexyl methacrylate (homopolymer Tg: 83°C)

[0275] HEA: 2-Hydroxyethyl Acrylate

[0276] 4HBA: 4-Hydroxybutyl acrylate

[0277] AA: Acrylic acid

[0278] <Examples 1 to 9, and Comparative Examples 1 and 2>

[0279] (1) Preparation of adhesive composition

[0280] The ethyl acetate solution of the (meth)acrylic resin obtained in the above production example (resin concentration: 20%) was mixed with the crosslinking agent, silane compound, and ionic compound in the amounts (parts by mass) shown in Table 2 relative to 100 parts by mass of the solid content of the solution. Ethyl acetate was then added to achieve a solid content concentration of 14% to prepare a solution of the adhesive composition. In Table 2, the amounts (parts by mass) of the (meth)acrylic resin, crosslinking agent, silane compound, and antistatic agent are expressed in terms of solid content.

[0281] [Table 2]

[0282]

[0283] The details of the ingredients indicated by the abbreviations in Table 2 are as follows.

[0284] [Crosslinking agent]

[0285] B: D-103 (ethyl acetate solution of trimethylolpropane adduct of toluene diisocyanate: solid content concentration 75% by mass, manufactured by Mitsui Chemicals, Inc.)

[0286] [Silane compound]

[0287] C-1: 8-glycidoxyoctyltrimethoxysilane "KBM-4803", manufactured by Shin-Etsu Chemical Co., Ltd.

[0288] C-2: 3-Glycidoxypropyltrimethoxysilane "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.

[0289] [Ionic compounds]

[0290] D: Methyltributylammonium = bis(trifluoromethylsulfonyl)imide

[0291] (2) Preparation of adhesive layer

[0292] Each adhesive composition prepared in the above (1) was applied to the release-treated surface of a separator made of a polyethylene terephthalate film ["Diafoil MRV38 (V04)" manufactured by Mitsubishi Chemical Corporation] using an applicator so that the thickness after drying was 25 μm, and dried at 100° C. for 1 minute to prepare an adhesive layer (adhesive sheet).

[0293] (3) Measurement of gel fraction of adhesive layer

[0294] The adhesive layer (adhesive sheet) prepared in (2) was stored at 23°C and 60% humidity for 7 days. The gel fraction of the adhesive layer (adhesive sheet) after storage [gel fraction at 23°C (G23)] was measured. The gel fraction can be measured according to the following [a] to [d]. The results are shown in Table 3.

[0295] [a] An adhesive layer having an area of ​​approximately 8 cm × 8 cm and a metal mesh made of SUS304 having an area of ​​approximately 10 cm × 10 cm (the mass thereof is denoted as Wm) are bonded together.

[0296] [b] The laminate obtained in [a] is weighed and its mass is set as Ws. It is then folded in half four times so as to cover the adhesive layer and secured with a stapler, and then weighed and its mass is set as Wb.

[0297] [c] The mesh fixed with staples in [b] was placed in a glass container, 60 mL of ethyl acetate was added and immersed, and the glass container was stored at room temperature for 3 days.

[0298] [d] The sieve was removed from the glass container, dried at 120°C for 4 hours, and weighed. The mass was designated as Wa, and the gel fraction was calculated according to the following formula:

[0299] Gel fraction (mass %)=[{Wa-(Wb-Ws)-Wm} / (Ws-Wm)]×100.

[0300] (4) Preparation of polarizing plate

[0301] A polarizing plate was prepared by laminating 40 μm thick protective films made of saponified triacetyl cellulose resin to both surfaces of a 12 μm thick polarizer prepared by adsorption and orientation of iodine on a uniaxially stretched polyvinyl alcohol film via an aqueous adhesive.

[0302] (5) Preparation of polarizing plate with adhesive layer

[0303] The surface of the adhesive layer produced in the above (2) that is opposite to the diaphragm (adhesive layer surface) is bonded to the outer surface of the protective film on one side of the polarizing plate produced in the above (4) by a laminating machine, and then maintained at a temperature of 23°C and a relative humidity of 60% for 7 days to obtain a polarizing plate with an adhesive layer.

[0304] (6) Evaluation of the Adhesion (Ease of Rework) of Laminated Optical Films

[0305] The polarizing plate with an adhesive layer obtained in step (5) was cut into a size of 150 mm × 25 mm so that the absorption axis of the polarizer became the long side. The separator was peeled off from the cut polarizing plate with an adhesive layer, and the exposed adhesive layer was attached to the center of an alkali-free glass substrate ("Eagle XG" manufactured by Corning Incorporated) with a height of 160 mm, a width of 50 mm, and a thickness of 0.7 mm. The substrate was then heated in an autoclave at a temperature of 50°C and a pressure of 5 kgf / cm 2 The obtained glass substrate-attached test piece (a polarizing plate with an adhesive layer attached to a glass substrate) was pressurized for 20 minutes at 490.3 kPa to prepare a sample, and then stored at 23°C and 55% relative humidity for 30 minutes.

[0306] Next, a knife blade was placed between the glass substrate and the adhesive layer, and the strip was peeled 30 mm from the end in the longitudinal direction. The peeled portion was then gripped by the clamps of a universal tensile testing machine (Shimadzu Corporation, trade name "AGS-50NX"). The test piece in this state was subjected to a 180-degree peel test at a clamp speed of 300 mm / minute in an environment at 23°C and 55% relative humidity, in accordance with JIS K 6854-2:1999, "Adhesives - Peel Adhesion Strength Test Methods - Part 2: 180-degree Peel." The average peel force over a length of 120 mm, after removing the 30 mm grip, was determined as the initial adhesion force at 23°C.

[0307] The adhesion strength was measured in the same manner as above except that the sample was stored in an environment of a temperature of 23° C. and a relative humidity of 55% for 4 weeks. The result is shown in Table 3.

[0308] When the adhesion force after lamination is 9.9 N / 25 mm or less and the difference between the initial adhesion force and the adhesion force after lamination is 3.9 N / 25 mm or less, the ease of rework is good.

[0309] (7) Evaluation of heat resistance and durability of laminated optical films

[0310] After peeling the separator from the polarizing plate with adhesive layer prepared in the above (5), the adhesive layer was attached to both sides of the alkali-free glass substrate ["Eagle XG" manufactured by Corning] in a manner of orthogonal Nicols. 2 The obtained glass substrate-attached test piece (polarizing plate with an adhesive layer attached to a glass substrate) was pressed at 490.3 kPa for 20 minutes to prepare an evaluation sample. The following heat resistance durability test was carried out using this sample.

[0311] [Heat resistance durability test]

[0312] The prepared sample was kept in a dry condition at a temperature of 110° C. for 750 hours.

[0313] The samples after each test were visually observed for swelling and peeling at the interface between the adhesive layer and the glass substrate, as well as for foaming of the adhesive layer, and heat resistance and durability were evaluated according to the following evaluation criteria.

[0314] A: Slight changes in appearance such as swelling, peeling, cracking, and foaming were observed.

[0315] B: Changes in appearance such as large swelling, peeling, cracking, and foaming were observed.

[0316] C: Changes in appearance such as significant swelling, peeling, cracking, and foaming were observed.

[0317] [Table 3]

[0318]

[0319] Explanation of symbols

[0320] 10, 20: Optical film with adhesive layer; 11, 24: Linear polarizing plate; 12: Adhesive layer; 13, 25: First protective film; 14, 16, 26, 28: Adhesive layer; 15, 27: Polarizer; 17, 29: Second protective film; 21: Adhesive layer; 22: Phase difference film; 23: Laminating layer; 30: Display device; 31: Liquid crystal display element.

Claims

1. An adhesive composition comprising a (meth)acrylic resin (A), a crosslinking agent (B), and a silane compound (C). The (meth)acrylic resin (A) comprises a structural unit derived from an alkyl methacrylate (a) having a homopolymer glass transition temperature of 30° C. or higher, a structural unit derived from a hydroxyl group-containing (meth)acrylate (b), and a structural unit derived from a carboxyl group-containing monomer (c). The silane compound (C) includes a compound represented by the following formula (i), In formula (i), A 1 represents an alkyl group having 1 to 5 carbon atoms, A 2 and A 3 each independently represents an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms, L represents an alkylene group having 8 to 20 carbon atoms or a group in which at least one methylene group constituting the alkylene group is replaced by a group selected from -NH- and -O-, X represents an epoxy group or an alicyclic epoxy group.

2. The adhesive composition according to claim 1, wherein The silane compound (C) is contained in an amount of 0.01 parts by mass or more and 2.0 parts by mass or less relative to 100 parts by mass of the (meth)acrylic resin (A).

3. The adhesive composition according to claim 1, wherein The (meth)acrylic resin (A) contains, relative to 100 parts by mass of all structural units constituting the (meth)acrylic resin (A), 1 part by mass or more and 15 parts by mass or less of structural units derived from the alkyl methacrylate (a) having a homopolymer glass transition temperature of 30° C. or higher, and 0.3 parts by mass or more and 5.5 parts by mass or less of structural units derived from the hydroxyl group-containing (meth)acrylate (b).

4. The adhesive composition according to claim 1, wherein The mass ratio (c) / (b) of the structural unit derived from the carboxyl group-containing monomer (c) to the structural unit derived from the hydroxyl group-containing (meth)acrylate (b) is 0.06 or more and 1.0 or less.

5. The adhesive composition according to claim 1, wherein The glass transition temperature of the homopolymer is 30° C. or higher. The glass transition temperature of the homopolymer of the alkyl methacrylate (a) is 80° C. or higher.

6. The adhesive composition according to any one of claims 1 to 5, wherein The alkyl methacrylate (a) having a glass transition temperature of 30° C. or higher of the homopolymer contains at least one selected from the group consisting of methyl methacrylate, t-butyl methacrylate, isobornyl methacrylate, and cyclohexyl methacrylate.

7. The adhesive composition according to any one of claims 1 to 5, wherein The weight average molecular weight of the (meth)acrylic resin (A) is 1,000,000 or more and 3,200,000 or less.

8. The adhesive composition according to any one of claims 1 to 5, wherein In the above formula (i), L represents an alkylene group having 8 to 12 carbon atoms or a group in which at least one methylene group constituting the above alkylene group is replaced by a group selected from -NH- and -O-.

9. The adhesive composition according to any one of claims 1 to 5, wherein The crosslinking agent (B) includes an aromatic isocyanate compound, and the adhesive composition contains 0.2 parts by mass or more and 5.0 parts by mass or less of the crosslinking agent (B) based on 100 parts by mass of the (meth)acrylic resin (A). 10 . An adhesive layer comprising the adhesive composition according to claim 1 . 11 . An optical film with a pressure-sensitive adhesive layer, comprising an optical film and the pressure-sensitive adhesive layer according to claim 10 laminated on the optical film.

12. The optical film with an adhesive layer according to claim 11, wherein The optical film includes a polarizer. 13 . A display device comprising the optical film with an adhesive layer according to claim 12 .

Images