Adhesive composition and optical film with adhesive layer

Abstract

The present invention provides an adhesive composition for obtaining an optical film with an adhesive layer that exhibits excellent reworkability after being left in a humid, heat-sensitive environment. [Solution] The adhesive composition contains a (meth)acrylic resin (A), a crosslinking agent (B), and a silane compound (C). The silane compound (C) includes a mercapto group-containing silane compound (C1) and an epoxy group-containing silane compound (C2). The content of the mercapto group-containing silane compound (C1) is greater than the content of the epoxy group-containing silane compound (C2).

Description

Technical Field

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

Background Art

[0002] A polarizing plate in which a protective film is laminated on at least one surface of a polarizer is used in a liquid crystal display device, an organic electroluminescent (organic EL) display device, and the like. An optical film such as a polarizing plate is used by being bonded to, for example, a liquid crystal cell of a liquid crystal display device or an organic EL element of an organic EL display device as an optical film with an adhesive layer in which an adhesive layer is laminated on at least one surface thereof (for example, Patent Document 1, etc.).

[0003] Patent Document 1 describes that the silane coupling agent contained in the adhesive includes an epoxy group-containing silane coupling agent and a mercapto group-containing silane coupling agent, and the content of the epoxy group-containing silane coupling agent is the same as or larger than the content of the mercapto group-containing silane coupling agent.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, Patent Document 1 does not describe improving the reworkability after leaving in a humid heat environment in an adhesive containing an epoxy group-containing silane coupling agent and a mercapto group-containing silane coupling agent.

[0006] An object of the present invention is to provide an adhesive composition for obtaining an optical film with an adhesive layer having excellent reworkability after leaving in a humid heat environment. [Means for solving the problem]

[0007] The present invention provides the following adhesive composition, adhesive layer, and optical film with adhesive layer. [1] An adhesive composition containing (meth)acrylic resin (A), a crosslinking agent (B), and a silane compound (C), The silane compound (C) comprises a mercapto group-containing silane compound (C1) and an epoxy group-containing silane compound (C2). An adhesive composition wherein the content of the mercapto group-containing silane compound (C1) is greater than the content of the epoxy group-containing silane compound (C2). [2] The adhesive composition according to [1], wherein the (meth)acrylic resin (A) has a weight-average molecular weight of 1 million or more, a glass transition temperature of -45°C or higher, and contains constituent units derived from (meth)acrylate having hydroxyl groups. [3] The adhesive composition according to [1] or [2], wherein the (meth)acrylic resin (A) further contains a constituent unit derived from an alkyl acrylate (a1) having a homopolymer glass transition temperature of less than 0°C, and a constituent unit derived from an alkyl acrylate (a2) having a homopolymer glass transition temperature of 0°C or higher. [4] The adhesive composition according to any one of [1] to [3], wherein the (meth)acrylic resin (A) further contains a constituent unit derived from an unsaturated monomer having one olefinic double bond and at least one aromatic ring in the molecule. [5] The adhesive composition according to any one of [1] to [4], wherein the (meth)acrylic resin (A) further contains constituent units derived from carboxyl group-containing (meth)acrylate. [6] The crosslinking agent (B) comprises an aromatic isocyanate crosslinking agent (B1), The adhesive composition according to any one of [1] to [5], wherein the content of the aromatic isocyanate crosslinking agent (B1) is 0.1 parts by mass or more and 4.5 parts by mass or less per 100 parts by mass of the (meth)acrylic resin (A). [7] The adhesive composition according to any one of [1] to [6], wherein the content of the mercapto group-containing silane compound (C1) is 0.1 parts by mass or more and 8 parts by mass or less per 100 parts by weight of the (meth)acrylic resin (A). [8] The adhesive composition according to any one of [1] to [7], further comprising an ionic compound (D). [9] An adhesive layer comprising the adhesive composition described in any of [1] to [8].

[10] An optical film with an adhesive layer, comprising an optical film and an adhesive layer according to [9] laminated on at least one surface thereof.

[11] The optical film with an adhesive layer according to

[10] , wherein the optical film comprises a polarizer and a protective film laminated on at least one surface thereof. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an optical film with an adhesive layer that exhibits excellent reworkability after being left in a humid, heat-sensitive environment. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view illustrating an example of the layer structure of an optical film with an adhesive layer according to the present invention. [Figure 2] This is a schematic cross-sectional view illustrating another example of the layer structure of the adhesive layer-equipped optical film according to the present invention. [Figure 3] This is a schematic cross-sectional view illustrating yet another example of the layer structure of the adhesive layer-equipped optical film according to the present invention. [Modes for carrying out the invention]

[0010] <Adhesive composition> The adhesive composition according to the present invention contains a (meth)acrylic resin (A), a crosslinking agent (B), and a silane compound (C). In the adhesive composition, the silane compound (C) includes a mercapto group-containing silane compound (C1) and an epoxy group-containing silane compound (C2), with the content of the mercapto group-containing silane compound (C1) being greater than the content of the epoxy group-containing silane compound (C2). The adhesive composition may further contain an ionic compound (D).

[0011] In this specification, "(meth)acrylic" means acrylic and / or methacrylic, and the same applies to "(meth)" in "(meth)acrylate, etc."

[0012] According to the above, an adhesive composition can be obtained for obtaining an optical film with an adhesive layer that exhibits excellent reworkability after being left in a humid, heat-sensitive environment. Reworkability after exposure to a humid and hot environment refers to the property that, as described in the examples below, for a sample in which an optical film with an adhesive layer is bonded to a glass substrate via the adhesive layer, the value of [ii] below can be suppressed to a certain level or lower, and when the optical film with the adhesive layer is peeled off after storage as described in [ii] below, clouding of the surface of the adherend and residue of the adhesive can be suppressed. It is also preferable that the property can suppress the difference between [i] and [ii] below. [i] Adhesion between the adhesive layer and the substrate after storage for a specified period under normal conditions [ii] The adhesion between the adhesive layer and the adherend after storage for a predetermined period under predetermined humid and heat conditions.

[0013] The following describes each component contained in the adhesive composition. <(Meth)acrylic resin (A)> The adhesive composition contains (meth)acrylic resin (A) from the viewpoint of transparency, tackiness, and reliability. The (meth)acrylic resin (A) contained in the adhesive composition may be one type or two or more types.

[0014] The (meth)acrylic resin (A) preferably has a weight-average molecular weight of 1 million or more, a glass transition temperature of -45°C or higher, and contains constituent units derived from (meth)acrylate having hydroxyl groups. The (meth)acrylic resin (A) preferably contains constituent units derived from (meth)acrylic acid ester, and may also contain constituent units derived from (meth)acrylate having a hydroxyl group, and other constituent units other than those derived from (meth)acrylic acid ester. The inclusion of a (meth)acrylic resin (A) containing the above-described structural units in the adhesive composition may be advantageous in improving the reworkability of the adhesive-coated optical film after being left in a humid, heat-sensitive environment. It may also be advantageous in improving the durability of the adhesive-coated optical film in heat resistance tests and heat shock tests. Durability in heat resistance tests and heat shock tests refers to the property of being able to suppress defects such as lifting or peeling at the interface between the adhesive layer of the optical film and the glass substrate to which it is bonded via the adhesive layer, as well as foaming of the adhesive layer, as described in the examples below.

[0015] The weight-average molecular weight (Mw) of the (meth)acrylic resin (A) is preferably 1 million or more, more preferably 1.2 million or more, even more preferably 1.4 million or more, particularly preferably 1.5 million or more, usually 2 million or less, may be 1.9 million or less, or 1.8 million or less. The molecular weight distribution, expressed as the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw / Mn), is usually 2 or more, preferably 3 or more, more preferably 4 or more, and also usually 10 or less, and may be 8 or less. The weight-average molecular weight (Mw) and number-average molecular weight (Mn) can be measured by gel permeation chromatography (GPC) using standard polystyrene equivalents.

[0016] The glass transition temperature of (meth)acrylic resin (A) is preferably -45°C or higher, more preferably -43°C or higher, even more preferably -42°C or higher, and usually -20°C or lower, but may also be -25°C or lower, or -30°C or lower, from the viewpoint of durability in heat resistance tests and heat shock tests. The glass transition temperature can be measured by differential scanning calorimeter (DSC).

[0017] [Constituent units derived from (meth)acrylate containing hydroxyl groups] From the viewpoint of the reactivity between the (meth)acrylic resin (A) and the crosslinking agent (B), it is preferable that the (meth)acrylic resin (A) contains constituent units derived from (meth)acrylate having hydroxyl groups.

[0018] Examples of (meth)acrylates having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-(2-hydroxyethoxy)ethyl (meth)acrylate, 2- or 3-chloro-2-hydroxypropyl (meth)acrylate, and diethylene glycol mono(meth)acrylate. The (meth)acrylic resin (A) may contain only one or more constituent units derived from (meth)acrylate having a hydroxyl group.

[0019] The content of constituent units derived from (meth)acrylate having hydroxyl groups is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and preferably 5% by mass or less, and more preferably 4% by mass or less, of the total constituent units constituting the (meth)acrylic resin (A), from the viewpoint of processability of the adhesive layer containing the adhesive composition and adhesion between the adhesive layer and the optical film.

[0020] [Constituent units derived from (meth)acrylic acid esters] The (meth)acrylic resin (A) is preferably a polymer containing as its main component a constituent unit derived from (meth)acrylic acid ester represented by the following formula (I). The main component means that its content in the total constituent units of the (meth)acrylic resin is 50% by mass or more. [ka] [In formula (I), R 1 This represents a hydrogen atom or a methyl group. R 2 This represents an alkyl group having 1 to 14 carbon atoms, which may be substituted with an alkoxy group having 1 to 10 carbon atoms, or an aralkyl group having 7 to 21 carbon atoms, which may be substituted with an alkoxy group having 1 to 10 carbon atoms.

[0021] R 2 In this case, when an aralkyl group is substituted with an alkoxy group, the number of carbon atoms in the aralkyl group is the number of carbon atoms excluding the carbon atoms of the alkoxy group. R 2 It is preferably an alkyl group having 1 to 14 carbon atoms, which may be substituted with an alkoxy group having 1 to 10 carbon atoms, and more preferably an alkyl group having 1 to 14 carbon atoms that is not substituted with such alkoxy group.

[0022] Examples of (meth)acrylic acid esters represented by formula (I) include, Alkyl (meth)acrylates having a linear alkyl ester moiety, such as methyl (meth)acrylate, ethyl (meth)acrylate, n- and i-propyl (meth)acrylate, n- and i-butyl (meth)acrylate, n- and i-octyl (meth)acrylate, and lauryl (meth)acrylate; Examples include alkyl(meth)acrylates having branched alkyl ester moieties, such as isobutyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, and isooctyl(meth)acrylate.

[0023] R2 If R is an alkyl group substituted with an alkoxy group, that is, 2 Examples of (meth)acrylic acid esters represented by formula (I) when is an alkoxyalkyl group include 2-methoxyethyl (meth)acrylate and ethoxymethyl (meth)acrylate. R 2 Examples of (meth)acrylic acid esters represented by formula (I) when the group has 7 to 21 carbon atoms include benzyl (meth)acrylate.

[0024] The (meth)acrylic resin (A) may contain only one or more constituent units derived from (meth)acrylic acid esters represented by formula (I). In particular, it is preferable that the constituent units derived from (meth)acrylic acid esters include constituent units derived from alkyl (meth)acrylate esters.

[0025] The (meth)acrylic resin (A) preferably contains, as constituent units derived from alkyl acrylate (a1) whose homopolymer glass transition temperature is less than 0°C, and constituent units derived from alkyl acrylate (a2) whose homopolymer glass transition temperature is 0°C or higher, as constituent units derived from alkyl (meth)acrylate ester. The inclusion of the (meth)acrylic resin (A) containing constituent units derived from alkyl acrylate (a1) and (a2) in the adhesive composition may be advantageous in obtaining an adhesive-coated optical film that improves reworkability after being left in a humid heat environment. It may also be advantageous in improving durability in heat resistance tests and heat shock tests. The Tg of the alkyl acrylate homopolymer can be based on literature values ​​such as those found in the POLYMER HANDBOOK (Wiley-Interscience).

[0026] Examples of alkyl acrylates (a1) include alkyl acrylates with approximately 2 to 12 carbon atoms in the alkyl group, such as ethyl acrylate, n- and i-propyl acrylate, n- and i-butyl acrylate, n-pentyl acrylate, n- and i-hexyl acrylate, n-heptyl acrylate, n- and i-octyl acrylate, 2-ethylhexyl acrylate, n- and i-nonyl acrylate, n- and i-decyl acrylate, and n-dodecyl acrylate. Another specific example of alkyl acrylate (a1) is substituent-containing alkyl acrylate, in which substituents are introduced to the alkyl group in alkyl acrylates with approximately 2 to 12 carbon atoms. The substituents in substituent-containing alkyl acrylate are groups that substitute for hydrogen atoms of the alkyl group, and specific examples include phenyl groups, alkoxy groups, and phenoxy groups. Specific examples of substituent-containing alkyl acrylate include 2-methoxyethyl acrylate, ethoxymethyl acrylate, phenoxyethyl acrylate, and phenoxydiethylene glycol acrylate. The alkyl group of alkyl acrylate (a1) is preferably a linear or branched alkyl group.

[0027] Alkyl acrylate (a1) may be used alone or in combination of two or more types. In particular, alkyl acrylate (a1) preferably contains one or more types selected from ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate. From the viewpoint of reworkability after being left in a humid heat environment, and durability in heat resistance tests and heat shock tests, alkyl acrylate (a1) preferably contains n-butyl acrylate.

[0028] The content of alkyl acrylate (a1)-derived constituent units in (meth)acrylic resin (A) is preferably 50 parts by mass or more, more preferably 55 parts by mass or more, even more preferably 60 parts by mass or more, and also preferably 90 parts by mass or less, more preferably 85 parts by mass or less, and even more preferably 81 parts by mass or less, out of 100 parts by mass of all constituent units constituting (meth)acrylic resin (A), from the viewpoint of reworkability after being left in a humid heat environment and durability in heat resistance tests and heat shock tests.

[0029] Alkyl acrylate (a2) is an alkyl acrylate other than alkyl acrylate (a1). Examples of alkyl acrylate (a2) include methyl acrylate, stearyl acrylate, and t-butyl acrylate.

[0030] Alkyl acrylate (a2) may be used alone or in combination of two or more types. In particular, from the viewpoint of reworkability after being left in a humid heat environment, and durability in heat resistance tests and heat shock tests, it is preferable that alkyl acrylate (a2) contains methyl acrylate.

[0031] The content of alkyl acrylate (a2)-derived constituent units in (meth)acrylic resin (A) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less, out of 100 parts by mass of all constituent units constituting (meth)acrylic resin (A).

[0032] In the (meth)acrylic resin (A), the total content of constituent units derived from alkyl acrylate (a1) and alkyl acrylate (a2) is preferably 60 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 80 parts by mass or more, and also preferably 99.9 parts by mass or less, and may be 99.5 parts by mass or less, or 99 parts by mass or less.

[0033] [Other monomers] The (meth)acrylic resin (A) may contain constituent units derived from (meth)acrylate having a hydroxyl group, as well as constituent units derived from monomers other than alkyl acrylates (a1) and (a2). The (meth)acrylic resin (A) may contain only one type of constituent unit derived from the other monomers, or it may contain two or more types.

[0034] Other monomers include unsaturated monomers having one olefinic double bond and at least one aromatic ring in the molecule (excluding those corresponding to the above-mentioned (meth)acrylates having a hydroxyl group and (meth)acrylic acid esters represented in (I) above), carboxyl group-containing (meth)acrylates, (meth)acrylates containing substituted or unsubstituted amino groups, (meth)acrylates containing heterocyclic groups such as epoxy groups, styrene monomers, vinyl monomers, monomers having multiple (meth)acryloyl groups in the molecule, (meth)acrylamide monomers, and the like.

[0035] The (meth)acrylic resin (A) preferably contains, and more preferably contains, at least one of the following as other monomers: an unsaturated monomer having one olefinic double bond and at least one aromatic ring in its molecule, and a carboxyl group-containing (meth)acrylate. Including one or both of these may be advantageous in improving reworkability after exposure to a humid, heat-sensitive environment. It may also be advantageous in improving durability in heat resistance tests and thermal shock tests.

[0036] Examples of the unsaturated monomer having one olefinic double bond and at least one aromatic ring in the molecule include (meth)acrylic monomers having an aromatic ring. Examples of the (meth)acrylic monomer having an aromatic ring include (meth)acrylic esters having an aryloxyalkyl group such as phenoxyethyl group-containing (meth)acrylic acid ester represented by the following formula (II), neopentyl glycol benzoate (meth)acrylate, and the like. [Chemical formula] [In formula (II), R 3 represents a hydrogen atom or a methyl group, n represents an integer of 1 or more and 8 or less, R 4 represents a hydrogen atom, an alkyl group, an aralkyl group or an aryl group.]

[0037] R 4 When it is an alkyl group, the carbon number thereof can be about 1 or more and 9 or less, when it is an aralkyl group, the carbon number thereof can be about 7 or more and 11 or less, and when it is an aryl group, the carbon number thereof can be about 6 or more and 10 or less.

[0038] Examples of the alkyl group having 1 or more and 9 or less carbon atoms constituting R 4 in formula (II) include a methyl group, a butyl group, a nonyl group, etc., examples of the aralkyl group having 7 or more and 11 or less carbon atoms include a benzyl group, a phenethyl group, a naphthylmethyl group, etc., and examples of the aryl group having 6 or more and 10 or less carbon atoms include a phenyl group, a tolyl group, a naphthyl group, etc., respectively.

[0039] Specific examples of phenoxyethyl group-containing (meth)acrylic acid esters represented by formula (II) include, for example, 2-phenoxyethyl (meth)acrylate, 2-(2-phenoxyethoxy)ethyl (meth)acrylate, (meth)acrylic acid ester of ethylene oxide-modified nonylphenol, and 2-(o-phenylphenoxy)ethyl (meth)acrylate. Phenoxyethyl group-containing (meth)acrylic acid esters may be used individually or in combination of two or more types. In particular, the phenoxyethyl group-containing (meth)acrylic acid ester preferably contains one or more selected from the group consisting of (meth)acrylic acid 2-phenoxyethyl, (meth)acrylic acid 2-(o-phenylphenoxy)ethyl, and (meth)acrylic acid 2-(2-phenoxyethoxy)ethyl, and more preferably contains one or more selected from the group consisting of (meth)acrylic acid 2-(o-phenylphenoxy)ethyl and (meth)acrylic acid 2-(2-phenoxyethoxy)ethyl.

[0040] The content of constituent units derived from unsaturated monomers having one olefinic double bond and at least one aromatic ring in the molecule of (meth)acrylic resin (A) may be 1 part by mass or more, 3 parts by mass or more, 5 parts by mass or more, usually 20 parts by mass or less, preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, out of 100 parts by mass of all constituent units constituting (meth)acrylic resin (A).

[0041] Examples of carboxyl group-containing (meth)acrylates include (meth)acrylic acid and carboxyethyl (meth)acrylate. The content of carboxyl group-containing (meth)acrylate-derived constituent units in (meth)acrylic resin (A) is preferably 2 parts by mass or less, more preferably 1.5 parts by mass or less, even more preferably 1 part by mass or less, usually 0.01 parts by mass or more, and may be 0.05 parts by mass or more, out of 100 parts by mass of all constituent units constituting (meth)acrylic resin (A).

[0042] Examples of (meth)acrylates containing substituted or unsubstituted amino groups include aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and dimethylaminopropyl (meth)acrylate. The content of constituent units derived from (meth)acrylate containing substituted or unsubstituted amino groups is preferably 2 parts by mass or less, more preferably 1.5 parts by mass or less, even more preferably 1 part by mass or less, usually 0.01 parts by mass or more, and may be 0.05 parts by mass or more, out of 100 parts by mass of all constituent units constituting the (meth)acrylic resin (A).

[0043] Examples of (meth)acrylates containing heterocyclic groups include acryloylmorpholine, vinylcaprolactam, N-vinyl-2-pyrrolidone, vinylpyridine, tetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, glycidyl (meth)acrylate, and 2,5-dihydrofuran. The content of constituent units derived from (meth)acrylate containing heterocyclic groups is preferably 2 parts by mass or less, more preferably 1.5 parts by mass or less, even more preferably 1 part by mass or less, and usually 0.01 parts by mass or more, and may be 0.05 parts by mass or more, out of 100 parts by mass of all constituent units constituting the (meth)acrylic resin (A).

[0044] Examples of styrene monomers include styrene; alkylstyrenes such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, and octylstyrene; halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene; and nitrostyrene, acetylstyrene, methoxystyrene, and divinylbenzene.

[0045] Examples of vinyl monomers 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; vinylidenes such as vinylidene chloride; nitrogen-containing aromatic vinyls such as vinylpyridine, vinylpyrrolidone, and vinylcarbazole; conjugated diene monomers such as butadiene, isoprene, and chloroprene; and acrylonitrile and methacrylonitrile.

[0046] Examples of monomers having multiple (meth)acryloyl groups in their molecule include monomers having two (meth)acryloyl groups in their 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 their molecule, such as trimethylolpropane tri(meth)acrylate.

[0047] Examples of (meth)acrylamide monomers 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, and N-isopropyl Pyr(meth)acrylamide, N-(3-dimethylaminopropyl)(meth)acrylamide, N-(1,1-dimethyl-3-oxobutyl)(meth)acrylamide, N-[2-(2-oxo-1-imidazolidinyl)ethyl](meth)acrylamide, 2-acryloylamino-2-methyl-1-propanesulfonic acid, N-(methoxymethyl)acrylamide, N-(ethoxymethyl)(meth)acrylamide, N-(propoxymethyl)(meth)acrylamide, N-(1-methyl 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 Examples include N-(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)(meth)acrylamide), N-(2-butoxyethyl)(meth)acrylamide, and N-[2-(1,1-dimethylethoxy)ethyl](meth)acrylamide. Among these, N-(methoxymethyl)acrylamide, N-(ethoxymethyl)acrylamide, N-(propoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, and N-(2-methylpropoxymethyl)acrylamide are preferred.

[0048] It is preferable that the (meth)acrylic resin (A) is substantially free of constituent units derived from (meth)acrylic acid esters having an alicyclic structure within the molecule. Substantially free of such constituent units means that the content of constituent units derived from (meth)acrylic acid esters having an alicyclic structure within the molecule is 0.5 parts by mass or less per 100 parts by mass of all constituent units constituting the (meth)acrylic resin (A), and the content may be 0.1 parts by mass or less, 0.05 parts by mass or less, or 0.01 parts by mass or less.

[0049] In (meth)acrylic acid esters having an alicyclic structure within the molecule, the alicyclic structure is typically a cycloparaffin structure with 5 or more carbon atoms, for example, 5 to 12 carbon atoms. Examples of (meth)acrylic acid esters having an alicyclic structure include isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, cyclododecyl (meth)acrylate, methylcyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclohexylphenyl (meth)acrylate, and cyclohexyl α-ethoxyacrylate.

[0050] [Manufacturing of (meth)acrylic resin (A)] (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 usually used in the production of (meth)acrylic resin (A). The polymerization initiator can be used in an amount of 0.001 parts by mass to 5 parts by mass per 100 parts by mass of all monomers used in the production of (meth)acrylic resin (A). Alternatively, (meth)acrylic resin (A) may be produced by a method in which polymerization is carried out by active energy rays such as ultraviolet light.

[0051] Polymerization initiators include thermal polymerization initiators and photopolymerization initiators. Examples of photopolymerization initiators include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone. Examples of thermal polymerization initiators include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonnitrile), 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); and lauryl peroxide. Examples include organic peroxides such as hydroxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxybenzoate, 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, redox initiators containing both peroxides and reducing agents can also be used as polymerization initiators.

[0052] As a method for producing (meth)acrylic resin (A), the solution polymerization method is preferred among the methods described above. An example of the solution polymerization method involves mixing the monomer and organic solvent to be used, adding a thermal polymerization initiator under a nitrogen atmosphere, and stirring for 3 to 15 hours at a temperature of approximately 40°C to 90°C, preferably 50°C to 80°C. To control the reaction, the monomer and thermal polymerization initiator may be added continuously or intermittently during polymerization, or added in a dissolved state in the organic solvent. Examples of organic solvents include aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; aliphatic alcohols such as propyl alcohol and isopropyl alcohol; and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone.

[0053] <Crosslinking agent (B)> The adhesive composition contains a crosslinking agent (B). The crosslinking agent (B) is a compound that reacts with polar functional groups (hydroxyl groups, carboxyl groups, amino groups, heterocyclic groups, amide groups, etc.) in the (meth)acrylic resin (A) to crosslink the (meth)acrylic resin (A). By using the crosslinking agent (B), the adhesion and heat resistance between the adhesive layer containing the adhesive composition and the optical film can be improved. The crosslinking agent (B) can be selected from isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, metal chelate-based crosslinking agents, and the like. The crosslinking agent (B) preferably contains an isocyanate-based crosslinking agent, and more preferably contains an aromatic isocyanate crosslinking agent (B1). Crosslinking agent (B) may be used alone or in combination of two or more types.

[0054] Isocyanate crosslinking agents are compounds having at least two isocyanate groups (-NCO) in their molecule. Examples of isocyanate crosslinking agents include hexamethylene diisocyanate, isophorone diisocyanate, and aromatic isocyanate crosslinking agents (B1). Aromatic isocyanate crosslinking agents (B1) are compounds having at least one aromatic ring and at least two isocyanate groups (-NCO) in their molecule. The adhesive composition preferably contains an aromatic isocyanate crosslinking agent (B1).

[0055] Examples of aromatic isocyanate crosslinking agents (B) include tolylene diisocyanate, chlorphenyl diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, polymethylene polyphenyl isocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. The aromatic isocyanate crosslinking agent (B) may be a derivative of these isocyanate compounds, such as polyhydric alcohol compound adducts (e.g., adducts with glycerol, trimethylolpropane, etc.), isocyanurates, biuret-type compounds, or urethane prepolymer-type isocyanate compounds obtained by addition reactions with polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, etc. Aromatic isocyanate crosslinking agents (B) may be used individually or in combination of two or more.

[0056] The content of aromatic isocyanate crosslinking agent (B) is 0.1 parts by mass or more per 100 parts by mass of (meth)acrylic resin (A), may be 0.5 parts by mass or more, or 1 part by mass or more. The content of aromatic isocyanate crosslinking agent (B) is 4.5 parts by mass or less per 100 parts by mass of (meth)acrylic resin (A), may be 4 parts by mass or less, or 3 parts by mass or less. By keeping the content of aromatic isocyanate crosslinking agent (B) within the above range, good durability in heat resistance tests and heat shock tests can be obtained.

[0057] Epoxy crosslinking agents are compounds that have at least two epoxy groups in their molecule. Examples of epoxy crosslinking agents include bisphenol A type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, N,N-diglycidylaniline, N,N,N',N'-tetraglycidyl-m-xylenediamine, and 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane. Epoxy crosslinking agents may be used individually or in combination of two or more types.

[0058] Aziridine crosslinking agents are compounds that have at least two three-membered ring skeletons, also known as ethyleneimines, consisting of one nitrogen atom and two carbon atoms, within their molecule. Examples of aziridine-based crosslinking agents 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. Aziridine crosslinking agents may be used individually or in combination of two or more types.

[0059] Examples of metal chelating crosslinking agents include compounds in which acetylacetone or ethyl acetoethyl is coordinated to polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. It is also possible to use a mixture of two or more metal chelating crosslinking agents.

[0060] The content of the crosslinking agent (B) in the adhesive composition is usually 5 parts by mass or less, preferably 2 parts by mass or less, per 100 parts by mass of the (meth)acrylic resin (A). The content of the crosslinking agent (B) in the adhesive composition is usually 0.05 parts by mass or more, and may be 0.1 parts by mass or more, per 100 parts by mass of the (meth)acrylic resin (A).

[0061] <Silane compound (C)> The adhesive composition contains a silane compound (C), and as silane compound (C), it includes a mercapto group-containing silane compound (C1) and an epoxy group-containing silane compound (C2). In the adhesive composition, the content of the mercapto group-containing silane compound (C1) is greater than the content of the epoxy group-containing silane compound (C2). This improves the reworkability of the adhesive composition containing both the mercapto group-containing silane compound (C1) and the epoxy group-containing silane compound (C2) after being left in a humid, heat-sensitive environment. The adhesive composition may also contain other silane compounds besides the mercapto group-containing silane compound (C1) and the epoxy group-containing silane compound (C2).

[0062] The total content of the mercapto group-containing silane compound (C1) and the epoxy group-containing silane compound (C2) in the adhesive composition is 0.1 parts by mass or more, may be 0.3 parts by mass or more, may be 1 part by mass or more, may be 3 parts by mass or more, or may be 8 parts by mass or less, may be 7.5 parts by mass or less, or may be 6 parts by mass or less, per 100 parts by mass of (meth)acrylic resin (A).

[0063] [Mercapto group-containing silane compound (C1)] A mercapto-containing silane compound (C1) is an organosilicon compound having at least one mercapto group (an organic group containing a mercapto group) and at least one alkoxysilyl group in its molecule.

[0064] Specific examples of mercapto group-containing silane compounds (C1) include: Mercapto group-containing low molecular weight silane compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane; Examples include mercapto group-containing oligomeric silane compounds such as copolymers of mercapto group-containing silane compounds like 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane with alkyl group-containing silane compounds such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. Examples of mercapto group-containing oligomeric silane compounds include, 3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, 3-Mercaptopropyltriethoxysilane-tetraethoxysilane copolymer Copolymers containing mercaptopropyl groups, etc. Mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, Mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, Mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, Mercaptomethyltriethoxysilane-tetraethoxysilane copolymer Examples include copolymers containing mercaptomethyl groups.

[0065] As the mercapto group-containing silane compound (C1), a mercapto group-containing oligomeric silane compound is preferred from the viewpoint of improving reworkability after being left in a humid and hot environment, a cocondensate of a mercapto group-containing silane compound and an alkyl group-containing silane compound is particularly preferred, and a cocondensate of 3-mercaptopropyltrimethoxysilane and methyltriethoxysilane is even more preferred. The molecular weight of the mercapto group-containing silane compound (C1) may be 200 or more, 500 or more, or 1000 or more. The molecular weight of the mercapto group-containing silane compound (C1) may be 30000 or less, 20000 or less, or 10000 or less. By having the molecular weight of the mercapto group-containing silane compound (C1) within the above range, the volatilization of the mercapto group-containing silane compound (C1) can be suppressed when the solvent-containing adhesive composition described later is applied to the film and dried, thereby improving the reworkability after being left in a humid and hot environment. The mercapto equivalent of the mercapto group-containing silane compound (C1) may be 200 g / mol or more, or 300 g / mol or more. The mercapto equivalent of the mercapto group-containing silane compound (C1) may be 1000 g / mol or less, or 850 g / mol or less. By having the mercapto equivalent of the mercapto group-containing silane compound (C1) within the above range, the reworkability after being left in a humid and hot environment can be improved. These may be used individually or in combination of two or more types.

[0066] The content of the mercapto group-containing silane compound (C1) may be 0.1 parts by mass or more, 0.3 parts by mass or more, 1 part by mass or more, or 3 parts by mass or more per 100 parts by mass of the (meth)acrylic resin (A). The content of the mercapto group-containing silane compound (C1) may be 8 parts by mass or less, 7.5 parts by mass or less, or 6 parts by mass or less per 100 parts by mass of the (meth)acrylic resin (A). By having the content of the mercapto group-containing silane compound (C1) within the above range, the reworkability after being left in a humid and hot environment can be improved.

[0067] The content of the mercapto group-containing silane compound (C1) is not particularly limited as long as it is greater than the content of the epoxy group-containing silane compound (C2). The content of the mercapto group-containing silane compound (C1) may be more than 1 times, 1.5 times or more, 2 times or more, preferably 5 times or more, more preferably 7 times or more, usually 20 times or less, and may also be 15 times or less.

[0068] [Epoxy group-containing silane compounds (C2)] Epoxy group-containing silane compounds (C2) are organosilicon compounds having at least one epoxy group (an organic group containing an epoxy group) and at least one alkoxysilyl group in their molecule.

[0069] Specific examples of epoxy group-containing silane compounds (C2) include: 3-glycidoxypropyltrimethoxysilanes such as 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane; 3-glycidoxypropyl alkyldialkoxysilanes such as 3-glycidoxypropylmethyldiethoxysilane and 3-glycidoxypropylmethyldimethoxysilane; Examples include methyltri(glycidyl)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and other 2-(3,4-epoxycyclohexyl)ethyltrialkoxysilanes. The epoxy group-containing silane compound (C2) may be of the silicone oligomer type. Examples of oligomer-type epoxy group-containing silane compounds (C2) include: 3-Glydidoxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-Glyzidoxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-Glyzidoxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-Glyzidoxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-Glydidoxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-Glydidoxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-Glydidoxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, Examples include copolymers containing a 3-glycidoxypropyl group, such as 3-glycidoxypropylmethyldiethoxysilane-tetraethoxysilane copolymer.

[0070] In particular, from the viewpoint of improving reworkability after being left in a humid and hot environment, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane are preferred, and 3-glycidoxypropyltrimethoxysilane is especially preferred. The epoxy group-containing silane compound (C2) may be used alone or in combination of two or more types.

[0071] The content of the epoxy group-containing silane compound (C2) may be 0.01 parts by mass or more, 0.05 parts by mass or more, or 0.1 parts by mass or more per 100 parts by mass of the (meth)acrylic resin (A). The content of the mercapto group-containing silane compound (C1) may be 5 parts by mass or less, 3 parts by mass or less, or 1 part by mass or less per 100 parts by mass of the (meth)acrylic resin (A). By having the content of the epoxy group-containing silane compound (C2) within the above range, the reworkability after being left in a humid and hot environment can be improved.

[0072] The content of the epoxy group-containing silane compound (C2) is not particularly limited as long as it is less than the content of the mercapto group-containing silane compound (C1). The content of the mercapto group-containing silane compound (C1) may be 0.8 times or less, 0.6 times or less, preferably 0.5 times or less, and usually 0.05 times or more, and may also be 0.1 times or more, compared to the content of the epoxy group-containing silane compound (C2).

[0073] [Other silane compounds] The adhesive composition may contain one or more silane compounds other than mercapto group-containing silane compounds (C1) and epoxy group-containing silane compounds (C2). Other silane compounds include acryloyl silane compounds, hydroxyl silane compounds, carboxyl silane compounds, amino silane compounds, amide silane compounds, and isocyanate silane compounds.

[0074] <Ionic compound (D)> The adhesive composition may contain an ionic compound (D). The ionic compound (D) can be used as an antistatic agent to impart antistatic properties to the adhesive layer containing the adhesive composition. The ionic compound (D) is a compound having an inorganic cation or organic cation and an inorganic anion or organic anion. The ionic compound (D) contained in the adhesive composition may be one or more types.

[0075] Examples of inorganic cations include lithium cations [Li + ], sodium cation [Na + ), potassium cation [K + Alkali metal ions such as [Be]; beryllium cations [Be] 2+ ], magnesium cation [Mg 2+ ], calcium cation [Ca 2+ Examples include alkaline earth metal ions such as [ ].

[0076] Examples of organic cations include imidazolium cations, pyridinium cations, pyrrolidinium cations, ammonium cations, sulfonium cations, and phosphonium cations.

[0077] Of the cationic components described above, organic cationic components are preferred because of their excellent compatibility with the adhesive composition. Among the organic cationic components, pyridinium cations and imidazolium cations are particularly preferred because they are less likely to become charged when peeling off the separator film provided on the adhesive layer containing the adhesive composition.

[0078] Examples of inorganic anions include the chloride anion [Cl - ], bromide anion [Br - ], Yodid 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 - ], dicyanamide anion [(CN)2N - ], hexafluorophosphate anion [PF6 - Examples include:

[0079] Examples of organic anions include acetate anions [CH3COO - ], trifluoroacetate anion [CF3COO - ], methanesulfonate anion [CH3SO3 - ], trifluoromethanesulfonate anion [CF3SO3 - ], p-toluenesulfonate anion [p-CH3C6H4SO3 - ], bis(fluorosulfonyl)imido anion [(FSO2)2N - ], bis(trifluoromethanesulfonyl)imido anion [(CF3SO2)2N - ], Tris(trifluoromethanesulfonyl)methanide anion [(CF3SO2)3C - ], dimethyl phosphinate anion [(CH3)2POO - ], (poly)hydrofluorofluoride anion [F(HF) m - ] (m is approximately 1 to 3), thiocyan anion [SCN - ], perfluorobutanesulfonate anion [C4F9SO3 - ], bis(pentafluoroethanesulfonyl)imide anion [(C2F5SO2)2N- ], perfluorobutanoate anion [C3F7COO - ], (trifluoromethanesulfonyl)(trifluoromethanecarbonyl)imido anion [(CF3SO2)(CF3CO)N - ], perfluoropropane-1,3-disulfonate anion [ - O3S(CF2)3SO3 - ], carbonate anion [CO3 2- Examples include:

[0080] Among the anionic components described above, anionic components containing a fluorine atom are particularly preferred because they provide an ionic compound (D) with excellent antistatic properties. Examples of anionic components containing a fluorine atom include hexafluorophosphate anions, bis(fluorosulfonyl)imide anions, hexafluorophosphate anions, or bis(trifluoromethanesulfonyl)imide anions.

[0081] Specific examples of ionic compounds (D) can be selected from the above combinations of cationic and anionic components. Examples of ionic compounds having organic cations are shown below, classified by the structure of the organic cation.

[0082] Pyridinium salts: N-hexylpyridinium hexafluorophosphate, N-hexyl-4-methylpyridinium hexafluorophosphate, N-octylpyridinium hexafluorophosphate, N-octyl-4-methylpyridinium hexafluorophosphate, N-butyl-4-methyllupyridinium hexafluorophosphate, N-decylpyridinium bis(fluorosulfonyl)imide, N-dodecylpyridinium bis(fluorosulfonyl)imide, N-tetradecylpyridinium bis(fluorosulfonyl)imide, N-Hexadecylpyridinium bis(fluorosulfonyl)imide, N-dodecyl-4-methylpyridinium bis(fluorosulfonyl)imide, N-tetradecyl-4-methylpyridinium bis(fluorosulfonyl)imide, N-Hexadecyl-4-methylpyridinium bis(fluorosulfonyl)imide, N-benzyl-2-methylpyridinium bis(fluorosulfonyl)imide, N-benzyl-4-methylpyridinium bis(fluorosulfonyl)imide, N-Hexylpyridinium bis(trifluoromethanesulfonyl)imide N-octylpyridinium bis(trifluoromethanesulfonyl)imide, N-octyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide, N-butyl-4-methyllupyridinium bis(trifluoromethanesulfonyl)imide.

[0083] Imidazolium salt: 1-Ethyl-3-methylimidazolium hexafluorophosphate, 1-Ethyl-3-methylimidazolium p-toluenesulfonate, 1-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide 1-Butyl-3-methylimidazolium methanesulfonate, 1-Butyl-3-methylimidazolium bis(fluorosulfonyl)imide.

[0084] Pyrrolidinium salts: N-butyl-N-methylpyrrolidinium hexafluorophosphate, N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide.

[0085] Quaternary ammonium salts: Tetrabutylammonium hexafluorophosphate, Tetrabutylammonium p-toluenesulfonate, (2-hydroxyethyl)trimethylammonium bis(trifluoromethanesulfonyl)imide (2-hydroxyethyl)trimethylammonium dimethylphosphine.

[0086] Examples of ionic compounds containing inorganic cations are shown below.

[0087] Lithium bromide, Lithium iodide, Lithium tetrafluoroborate, Lithium hexafluorophosphate, Lithium thiocyanate, Lithium perchlorate, Lithium trifluoromethanesulfonate, Lithium bis(fluorosulfonyl)imide, Lithium bis(trifluoromethanesulfonyl)imide, Lithium bis(pentafluoroethanesulfonyl)imide, Lithium tris(trifluoromethanesulfonyl)methanide, Lithium p-toluenesulfonate, Sodium hexafluorophosphate, Sodium bis(fluorosulfonyl)imide, Sodium bis(trifluoromethanesulfonyl)imide, Sodium p-toluenesulfonate, Potassium hexafluorophosphate, Potassium bis(fluorosulfonyl)imide, Potassium bis(trifluoromethanesulfonyl)imide, Potassium p-toluenesulfonate.

[0088] The ionic compound (D) is preferably a solid at room temperature. Using an ionic compound (D) that is a solid at room temperature allows for longer-term maintenance of antistatic performance compared to using an ionic compound (D) that is a liquid at room temperature. From the viewpoint of long-term stability of antistatic properties, the ionic compound is preferably having a melting point of 30°C or higher, and more preferably 35°C or higher. On the other hand, if the melting point is too high, the compatibility with the (meth)acrylic resin (A) deteriorates, so the melting point of the ionic compound (D) is preferably 90°C or lower, more preferably 70°C or lower, and even more preferably less than 50°C.

[0089] The content of the ionic compound (D) in the adhesive composition is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.3 parts by mass or more, particularly preferably 1 part by mass or more, and also preferably 10 parts by mass or less, more preferably 9 parts by mass or less, and even more preferably 8 parts by mass or less, per 100 parts by mass of (meth)acrylic resin (A). Having the content of ionic compound (D) within the above range is advantageous for improving the antistatic performance of the adhesive layer containing the adhesive composition.

[0090] <Other ingredients> The adhesive composition may also contain other components besides the (meth)acrylic resin (A), crosslinking agent (B), silane compound (C), and ionic compound (D) described above. Other components may include additives such as resins other than (meth)acrylic resin (A), crosslinking catalysts, weather stabilizers, tackifiers, plasticizers, softeners, dyes, pigments, inorganic fillers, and light-scattering fine particles. In addition, an adhesive composition can be formulated with an ultraviolet-curable compound, and after forming the adhesive layer, it can be cured by irradiation with ultraviolet light to create a harder adhesive layer.

[0091] <Adhesive layer> The adhesive layer according to the present invention comprises the adhesive composition described above. The adhesive layer can be obtained by dissolving or dispersing each component constituting the adhesive composition in a solvent to form a solvent-containing adhesive composition, then applying it to a base film or optical film and drying it. Examples of solvents include the organic solvents exemplified in the production of the (meth)acrylic resin described above.

[0092] The base film is generally a thermoplastic resin film, and a typical example of this is a release-treated separator film. Examples of separator films include those made of resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, and polyalate, on which a release treatment such as silicone treatment is applied to the surface where the adhesive layer is formed. For example, an adhesive sheet, formed by directly applying an adhesive composition to the release surface of a separator film to create an adhesive layer, may be laminated onto an optical film or the like. The adhesive sheet may also have another separator film laminated on the side opposite to the separator film of the adhesive layer. If the adhesive sheet has separator films on both sides of the adhesive layer, one of the separator films can be peeled off and the exposed adhesive layer can be laminated onto the optical film or the like.

[0093] When providing an adhesive layer on the surface of an optical film, it is preferable to apply a surface activation treatment, such as plasma treatment or corona treatment, to the bonding surface of the optical film and / or the bonding surface of the adhesive layer, and it is more preferable to apply a corona treatment.

[0094] The thickness of the adhesive layer is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and also preferably 45 μm or less, more preferably 30 μm or less, and even more preferably 25 μm or less. Having the adhesive layer thickness within the above range can be advantageous in suppressing the decrease in adhesion over time.

[0095] <Optical film with adhesive layer> Figures 1 to 3 are schematic cross-sectional views illustrating an example of the layer structure of an optical film with an adhesive layer according to the present invention. As shown in Figures 1 to 3, the optical film with an adhesive layer 1 comprises an optical film 10 and an adhesive layer 20 laminated on at least one surface thereof, which contains the adhesive composition described above. The adhesive layer 20 is usually laminated directly onto the surface of the optical film 10. The adhesive layer-coated optical film 1 may have a separator film on the side of the adhesive layer 20 opposite to the optical film 10 side.

[0096] The optical film 1 with an adhesive layer exhibits excellent reworkability after being left in a humid and hot environment, because the adhesive layer 20 is formed of the adhesive composition described above.

[0097] The optical film 10 can be any type of optical film (a film having optical properties) that can be incorporated into a liquid crystal display device or an organic EL display device. The optical film 10 may be a single-layer optical film or a multi-layer optical film.

[0098] Specific examples of single-layer optical films include optical functional films such as polarizers, phase difference films, brightness enhancement films, anti-glare films, anti-reflective films, diffusion films, and light-gathering films.

[0099] Examples of multilayer optical films include polarizers and phase difference plates. In this specification, a polarizer refers to a polarizer 12 (Figures 2 and 3) on which protective films 13, 14 (Figures 2 and 3) or a resin layer are laminated on at least one surface. A phase difference plate refers to a phase difference film on which a protective film or resin layer is laminated to at least one side. When the optical film 1 with an adhesive layer includes a polarizing plate as the optical film 10, the polarizing plate may have a structure in which protective films 13 and 14 are laminated on one or both sides of the polarizer 12, as shown in Figures 2 and 3. When the polarizing plate in the optical film 1 with an adhesive layer has a protective film 13 on only one side, it is preferable that the adhesive layer 20 is provided on the polarizer 12 side of the polarizing plate, as shown in Figure 2.

[0100] The optical film 10 is preferably a polarizing plate, polarizer, phase difference plate, or phase difference film, and more preferably a polarizing plate or polarizer.

[0101] The adhesive layer 20 can be used to bond the adhesive-coated optical film 1 to, for example, an image display element or the like.

[0102] The optical film 1 with an adhesive layer may be formed by directly applying an adhesive composition to the surface of the optical film 10 to form an adhesive layer 20, and if necessary, laminating a separator film onto the outer surface of the adhesive layer 20. Alternatively, an adhesive layer 20 can be formed by directly applying an adhesive composition to the release surface of the separator film, and this adhesive layer with separator film can be laminated onto the optical film 10 to obtain an optical film 1 with an adhesive layer having a separator film.

[0103] [polarizer] The polarizer 12 is a film that absorbs linearly polarized light having a vibration plane parallel to its absorption axis and transmits linearly polarized light having a vibration plane perpendicular to the absorption axis (parallel to the transmission axis). The polarizer 12 may be, for example, a film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film, or it may be a cured film in which a dichroic dye is oriented on a polymerizable liquid crystal compound and the polymerizable liquid crystal compound is polymerized.

[0104] Polyvinyl alcohol-based resins can be obtained by saponifying polyvinyl acetate-based resins. Examples of polyvinyl acetate-based resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate with monomers copolymerizable with vinyl acetate. Examples of monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamide having an ammonium group. Dichroic dyes include iodine and dichroic organic dyes.

[0105] The degree of saponification of polyvinyl alcohol-based resins is typically 85 to 100 mol%, preferably 98 mol% or higher. Polyvinyl alcohol-based resins may be modified; for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can be used. The average degree of polymerization of polyvinyl alcohol-based resins is typically 1000 to 10000, preferably 1500 to 5000. The average degree of polymerization of polyvinyl alcohol-based resins can be determined in accordance with JIS K 6726.

[0106] Typically, a film made from polyvinyl alcohol-based resin is used as the base film for the polarizer 12. The polyvinyl alcohol-based resin can be manufactured by known methods. The thickness of the base film is usually 1 to 150 μm, and preferably 10 μm or more, taking into consideration ease of stretching.

[0107] The polarizer 12, which is a film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film, is manufactured by, for example, subjecting the raw film to a process of uniaxial stretching, dyeing the film with a dichroic dye and adsorbing the dichroic dye, treating the film with an aqueous boric acid solution, washing the film with water, and finally drying it. The thickness of the polarizer 12 is usually 1 to 30 μm, and from the viewpoint of thinning the optical film 1 with the adhesive layer, it is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less.

[0108] A polarizer 12 formed by adsorbing and aligning a dichroic dye onto a polyvinyl alcohol-based resin film can be obtained by: 1) using a single polyvinyl alcohol-based resin film as the base film and subjecting this film to uniaxial stretching and dyeing with a dichroic dye; or 2) applying a coating solution (aqueous solution, etc.) containing polyvinyl alcohol-based resin to a base film, drying it to obtain a base film having a polyvinyl alcohol-based resin layer, then uniaxially stretching the base film together, subjecting the stretched polyvinyl alcohol-based resin layer to dyeing with a dichroic dye, and then peeling off the base film. As the base film, a film made of a thermoplastic resin similar to the thermoplastic resins that can constitute the protective films 13 and 14 described later can be used, and preferably a film made of polyester resins such as polyethylene terephthalate, polycarbonate resins, cellulose resins such as triacetylcellulose, cyclic polyolefin resins such as norbornene resins, polystyrene resins, etc.

[0109] A method for producing a polarizer 12, which is a cured film obtained by oriented a dichroic dye on a polymerizable liquid crystal compound and polymerizing the polymerizable liquid crystal compound, is to apply a polarizing layer-forming composition containing a polymerizable liquid crystal compound and a dichroic dye onto a base film, and polymerize and cure the polymerizable liquid crystal compound while maintaining its liquid crystal state to form the polarizer 12. The polarizer 12 obtained in this way is laminated on the base film, and the polarizer with the base film may be used as a polarizing plate. The above-mentioned base film can be used.

[0110] As dichroic dyes, dyes having different absorbances along the long axis and short axis of the molecule can be used. For example, dyes having an absorption maximum wavelength (λmax) in the range of 300 to 700 nm are preferred. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes, with azo dyes being preferred. Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbenazo dyes, with bisazo dyes and trisazo dyes being more preferred.

[0111] The polarizing layer-forming composition may include a solvent, polymerization initiators such as photopolymerization initiators, photosensitizers, polymerization inhibitors, etc. The polymerizable liquid crystal compounds, dichroic dyes, solvents, polymerization initiators, photosensitizers, polymerization inhibitors, etc., included in the polarizing layer-forming composition may be those of known origin; for example, those exemplified in Japanese Patent Publication No. 2017-102479 and Japanese Patent Publication No. 2017-83843 can be used. The method for forming a linearly polarized layer using the polarizing layer-forming composition may also be the method exemplified in the above publications.

[0112] [Protective film] Each of the protective films 13 and 14 can be independently a film made of a light-transmitting, preferably optically transparent, thermoplastic resin, such as a polyolefin resin like a chain polyolefin resin (polyethylene resin, polypropylene resin, etc.) or a cyclic polyolefin resin (norbornene resin, etc.); a cellulose resin (cellulose ester resin, etc.); a polyester resin (polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc.); a polycarbonate resin; a (meth)acrylic resin; a polystyrene resin; a polyether ether ketone resin; a polysulfone resin; or a mixture or copolymer thereof. In particular, each of the protective films 13 and 14 is preferably composed of a resin selected from the group consisting of cyclic polyolefin resins, polycarbonate resins, cellulose resins, polyester resins, and (meth)acrylic resins, and more preferably composed of a resin selected from the group consisting of cellulose resins, cyclic polyolefin resins, and (meth)acrylic resins.

[0113] Examples of chain-like polyolefin resins include homopolymers of chain-like olefins such as polyethylene resin and polypropylene resin, as well as copolymers composed of two or more chain-like olefins.

[0114] Cyclic polyolefin resins are a general term for resins that contain cyclic olefins as polymerization units, with norbornene, tetracyclododecene (also known as dimethanooctahydronaphthalene), or their derivatives being typical examples. Specific examples of cyclic polyolefin resins include ring-opening (co)polymers of cyclic olefins and their hydrogenated products, addition polymers of cyclic olefins, copolymers of cyclic olefins with chain-like olefins such as ethylene and propylene, or aromatic compounds having vinyl groups, and modified (co)polymers obtained by modifying these with unsaturated carboxylic acids or their derivatives. Among these, norbornene-based resins using norbornene monomers such as norbornene or polycyclic norbornene monomers as the cyclic olefin are preferred.

[0115] Cellulose resins are preferably cellulose ester resins, i.e., partial or complete esterified cellulose, such as cellulose acetate esters, propionic acid esters, butyrate esters, and mixed esters thereof. Among these, triacetylcellulose, diacetylcellulose, cellulose acetate propionate, and cellulose acetate butyrate are preferably used.

[0116] Polyester resins are resins other than the cellulose ester resins mentioned above that have ester bonds, and are generally composed of polycondensates of polycarboxylic acids or their derivatives and polyhydric alcohols. Specific examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethyl terephthalate, and polycyclohexanedimethyl naphthalate.

[0117] Polycarbonate resins are polyesters formed from carbonic acid and glycol or bisphenol. Among these, aromatic polycarbonates having diphenylalkanes in their molecular chains are preferred from the viewpoint of heat resistance, weather resistance, and acid resistance. Examples of polycarbonates include polycarbonates derived from bisphenols such as 2,2-bis(4-hydroxyphenyl)propane (also known as bisphenol A), 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)isobutane, and 1,1-bis(4-hydroxyphenyl)ethane.

[0118] The (meth)acrylic resin that can constitute the protective films 13 and 14 may be a polymer mainly composed of structural units derived from methacrylic acid esters (for example, containing 50% by mass or more of these), and it is preferable that it is a copolymer in which other copolymer components are copolymerized thereto. The (meth)acrylic resin may contain two or more structural units derived from methacrylic acid esters. Examples of methacrylic acid esters include C1-C4 alkyl esters of methacrylic acid such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate.

[0119] Examples of copolymers that can copolymerize with methacrylic acid esters include acrylic acid esters. Preferably, the acrylic acid esters are C1-C8 alkyl esters of acrylic acid, such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Other specific examples of copolymers include unsaturated acids such as (meth)acrylic acid; aromatic vinyl compounds such as styrene, halogenated styrene, α-methylstyrene, and vinyltoluene; vinyl cyanide compounds such as (meth)acrylonitrile; unsaturated anhydrides such as maleic anhydride and citraconic anhydride; and unsaturated imides such as phenylmaleimide and cyclohexylmaleimide. These are compounds other than acrylic acid esters that have one polymerizable carbon-carbon double bond in their molecule. Compounds having two or more polymerizable carbon-carbon double bonds in their molecule may also be used as copolymers. Only one copolymer may be used, or two or more may be used in combination.

[0120] (Meth)acrylic resins may have a ring structure in their polymer main chain, which can enhance the durability of the film. The ring structure is preferably a heterocyclic structure such as a cyclic acid anhydride structure, a cyclic imide structure, or a lactone ring structure. Specific examples of cyclic acid anhydride structures include glutaric acid anhydride and succinic acid anhydride; specific examples of cyclic imide structures include glutarimide and succinimide; and specific examples of lactone ring structures include butyrolactone and valerolactone ring structures.

[0121] (Meth)acrylic resins may contain acrylic rubber particles from the viewpoint of film-forming properties and film impact resistance. Acrylic rubber particles are particles whose essential component is an elastic polymer mainly composed of acrylic acid esters, and include single-layer structures consisting substantially only of this elastic polymer, and multilayer structures with an elastic polymer as one layer. An example of an elastic polymer is a crosslinked elastic copolymer obtained by copolymerizing alkyl acrylate as the main component with other copolymerizable vinyl monomers and crosslinkable monomers. Examples of alkyl acrylates that are the main component of the elastic polymer include C1 to C8 alkyl esters of acrylic acid such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. The number of carbon atoms in the alkyl group is preferably 4 or more.

[0122] Other vinyl monomers copolymerizable with alkyl acrylate include compounds having one polymerizable carbon-carbon double bond in the molecule, more specifically, methacrylic acid esters such as methyl methacrylate, aromatic vinyl compounds such as styrene, and vinyl cyanide compounds such as (meth)acrylonitrile. Crosslinkable monomers include crosslinkable compounds having at least two polymerizable carbon-carbon double bonds in the molecule, more specifically, (meth)acrylates of polyhydric alcohols such as ethylene glycol di(meth)acrylate and butanediol di(meth)acrylate, alkenyl esters of (meth)acrylic acid such as allyl (meth)acrylate, and divinylbenzene.

[0123] The content of acrylic rubber particles is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, per 100 parts by mass of (meth)acrylic resin. If the content of acrylic rubber particles is too high, the surface hardness of the film will decrease, and the solvent resistance to organic solvents in the surface treatment agent may decrease when the film is surface-treated. Therefore, the content of acrylic rubber particles is usually 80 parts by mass or less, preferably 60 parts by mass or less, per 100 parts by mass of (meth)acrylic resin.

[0124] The protective films 13 and 14 may contain additives that are common in the art of the present invention. Specific examples of additives include, for example, ultraviolet absorbers, infrared absorbers, organic dyes, pigments, inorganic dyes, antioxidants, antistatic agents, surfactants, lubricants, dispersants, and heat stabilizers.

[0125] Examples of UV absorbers include salicylate compounds, benzophenone compounds, benzotriazole compounds, triazine compounds, cyano(meth)acrylate compounds, and nickel complex salts.

[0126] The protective films 13 and 14 may each be either an unstretched film or a uniaxially or biaxially stretched film. Biaxial stretching may be simultaneous biaxial stretching, where the film is stretched simultaneously in two stretching directions, or sequential biaxial stretching, where the film is stretched in one direction first and then in another. The protective film 13 and / or protective film 14 may be protective films that serve to protect the polarizer 12, or they may be protective films that also have optical functions, such as a phase difference film, as described later. A phase difference film is an optical film that exhibits optical anisotropy. For example, a phase difference film can be made to which an arbitrary phase difference value is assigned by stretching (uniaxially or biaxially stretching, etc.) a film made of the thermoplastic resin, or by forming a liquid crystal layer, etc., on the thermoplastic resin film.

[0127] The protective films 13 and 14 may be films made of the same thermoplastic resin, or they may be films made of different thermoplastic resins. The protective films 13 and 14 may be the same or different in terms of thickness, presence and type of additives, phase difference characteristics, etc.

[0128] The protective film 13 and / or protective film 14 may have surface treatment layers (coating layers) such as a hard coat layer, an anti-glare layer, an anti-reflective layer, a light-diffusing layer, an anti-static layer, an anti-fouling layer, or a conductive layer on its outer surface (the surface opposite to the polarizer 12).

[0129] The thickness of the protective films 13 and 14 is typically 1 to 150 μm, preferably 5 to 100 μm, and more preferably 5 to 60 μm. The thickness may be 50 μm or less, and even 30 μm or less. Reducing the thickness of the protective films 13 and 14 is advantageous for thinning the adhesive layer-attached optical film 1 and the display device containing it.

[0130] The protective films 13 and 14 can be bonded to the polarizer 12 via an adhesive layer or a tack layer. As the adhesive forming the adhesive layer, a water-based adhesive or an active energy ray-curable adhesive can be used.

[0131] Examples of water-based adhesives include adhesives made from aqueous solutions of polyvinyl alcohol-based resins and water-based two-component urethane emulsion adhesives. Among these, water-based adhesives made from aqueous solutions of polyvinyl alcohol-based resins are preferred. As polyvinyl alcohol-based resins, vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as polyvinyl alcohol copolymers obtained by saponifying a copolymer of vinyl acetate and other monomers copolymerizable thereto, or modified polyvinyl alcohol polymers obtained by partially modifying the hydroxyl groups thereof. Water-based adhesives may contain crosslinking agents such as aldehyde compounds, epoxy compounds, melamine compounds, methylol compounds, isocyanate compounds, amine compounds, and polyvalent metal salts.

[0132] When using a water-based adhesive, it is preferable to perform a drying step to remove the water contained in the water-based adhesive after bonding the polarizer 12 and the protective films 13 and 14. After the drying step, a curing step may be provided in which the adhesive is cured at a temperature of, for example, 20 to 45°C.

[0133] The above-mentioned active energy ray curable adhesive refers to an adhesive that hardens when irradiated with active energy rays such as ultraviolet rays or electron beams. Examples include a curable composition containing a polymerizable compound and a photopolymerization initiator, a curable composition containing a photoreactive resin, a curable composition containing a binder resin and a photoreactive crosslinking agent, etc. Preferably, it is an ultraviolet-curable adhesive. Examples of polymerizable compounds include photopolymerizable monomers such as photocurable epoxy monomers, photocurable (meth)acrylic monomers, and photocurable urethane monomers, and oligomers derived from photopolymerizable monomers. Examples of photopolymerization initiators include substances that generate active species such as neutral radicals, anionic radicals, and cationic radicals when irradiated with active energy rays. As an active energy ray curable adhesive containing a polymerizable compound and a photopolymerization initiator, a curable composition containing a photocurable epoxy monomer and a photocationic polymerization initiator, a curable composition containing a photocurable (meth)acrylic monomer and a photoradical polymerization initiator, or a mixture of these curable compositions can preferably be used.

[0134] When using an active energy ray curable adhesive, after bonding the polarizer 12 and protective films 13 and 14, a drying process is performed as needed, followed by a curing process in which the active energy ray curable adhesive is cured by irradiation with active energy rays. The light source for the active energy rays is not particularly limited, but ultraviolet light having an emission distribution of wavelengths of 400 nm or less is preferred. Specifically, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, etc., can be used.

[0135] When bonding the polarizer 12 to the protective films 13 and 14, surface activation treatments such as saponification, corona treatment, or plasma treatment can be applied to at least one of the bonding surfaces. When protective films 13 and 14 are bonded to both sides of the polarizer 12, the adhesive used to bond these protective films 13 and 14 may be the same type of adhesive or different types of adhesives.

[0136] [Polarizing plate] The polarizing plate may further include other films or layers besides the polarizer 12 and protective films 13 and 14. Other films or layers include, in addition to the phase difference film described later, brightness-enhancing films, anti-glare films, anti-reflective films, diffusion films, light-gathering films, adhesive layers other than the adhesive layer 20, coating layers, protective films, etc. The protective film is a film used to protect the surface of the optical film 10, such as the polarizing plate, from scratches and dirt, and is typically peeled off after the optical film 1 with an adhesive layer is bonded to an object such as an image display element.

[0137] Protective films typically consist of a base film and an adhesive layer laminated on top of it. The base film can be made of thermoplastic resins, such as polyolefin resins like polyethylene resins and polypropylene resins; polyester resins like polyethylene terephthalate and polyethylene naphthalate; polycarbonate resins; (meth)acrylic resins, etc.

[0138] [Phase plate] The phase difference film included in the phase difference plate is an optical film exhibiting optical anisotropy. In addition to the thermoplastic resins exemplified above that can be used for protective films 13 and 14, it can also be a stretched film obtained by stretching a resin film made of, for example, polyvinyl alcohol resin, polyarylate resin, polyimide resin, polyethersulfone resin, polyvinylidene fluoride / polymethyl methacrylate resin, liquid crystal polyester resin, ethylene-vinyl acetate copolymer saponified, polyvinyl chloride resin, etc., to about 1.01 to 6 times its original length. Among these, stretched films obtained by uniaxially or biaxially stretching polycarbonate resin films, cyclic olefin resin films, (meth)acrylic resin films, or cellulose resin films are preferred. In this specification, zero retardation films are also included in the phase difference film (however, they can also be used as protective films). In addition, films referred to as uniaxial phase difference films, wide-viewing-angle phase difference films, low-photomodulus phase difference films, etc., can also be applied as phase difference films.

[0139] A zero-retardation film is defined by the in-plane phase difference value R. e and the phase difference value R in the thickness direction th This refers to a film where both phase differences are between -15 and 15 nm. This phase difference film is suitably used in IPS mode liquid crystal display devices. In-plane phase difference value R e and the phase difference value R in the thickness direction th The in-plane phase difference value R is preferably -10 to 10 nm for both, and more preferably -5 to 5 nm for both. e and the phase difference value R in the thickness direction th This value is at a wavelength of 590 nm.

[0140] In-plane phase difference value R e and the phase difference value R in the thickness direction th These are defined by the following formulas. R e =(n x -n y )×d R th = [(n x +n y) / 2-n z ] × d [where n x is the refractive index in the slow phase axis direction (x-axis direction) within the film plane, and n y n is the refractive index in the phase-advancing axis direction within the film plane (the y-axis direction perpendicular to the x-axis within the plane), and n z is the refractive index in the film thickness direction (the z-axis direction perpendicular to the film surface), and d is the film thickness.

[0141] For the zero retardation film, a resin film made of polyolefin resins such as cellulose resins, chain polyolefin resins, and cyclic polyolefin resins, polyethylene terephthalate resins, or (meth)acrylic resins can be used. Cellulose resins, polyolefin resins, or (meth)acrylic resins are particularly preferred because they allow for easy control of the phase difference value and are readily available.

[0142] Furthermore, films that exhibit optical anisotropy through the coating and orientation of liquid crystalline compounds, and films that exhibit optical anisotropy through the coating of inorganic layered compounds, can also be used as phase difference films. Examples of such phase difference films include temperature-compensated phase difference films, films with tilted orientation of rod-shaped liquid crystals sold by JX Nippon Oil & Energy Corporation under the product name "NH Film", films with tilted orientation of disc-shaped liquid crystals sold by Fujifilm Corporation under the product name "WV Film", fully biaxially oriented films sold by Sumitomo Chemical Co., Ltd. under the product name "VAC Film", and biaxially oriented films also sold by Sumitomo Chemical Co., Ltd. under the product name "new VAC Film".

[0143] The protective film laminated on at least one surface of the phase difference film can be, for example, the protective films 13 and 14 described above.

[0144] [Applications of optical films with adhesive layers] The adhesive-coated optical film 1 described above can be incorporated into display devices such as liquid crystal displays and organic EL displays. In this case, the adhesive-coated optical film 1 can be bonded to the image display element of the display device via the adhesive layer 20. Examples of image display elements include liquid crystal panels and organic EL elements.

[0145] The adhesive-coated optical film 1 also exhibits excellent reworkability after being left in a humid, heat-sensitive environment, thus suppressing the occurrence of clouding, dirt, and other issues on the surface of the image display element during rework. [Examples]

[0146] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Hereinafter, parts and % representing the amount used or content are based on mass unless otherwise specified.

[0147] <Manufacturing Examples 1-5: Manufacturing of (meth)acrylic resins> A reaction vessel equipped with a condenser, a nitrogen inlet, a thermometer, and a stirrer was charged with a monomer mixture prepared by diluting the monomer composition shown in Table 1 (parts by mass, assuming a total monomer volume of 100 parts by mass) with ethyl acetate. The internal temperature was raised to 55°C while replacing the air in the reaction vessel with nitrogen gas to eliminate oxygen. Then, the entire solution of azobisisobutyronitrile (polymerization initiator) dissolved in ethyl acetate was added. After adding the polymerization initiator, the temperature was maintained at this level for 1 hour, and then ethyl acetate was continuously added to the reaction vessel while maintaining the internal temperature at 54-56°C. The addition of ethyl acetate was stopped when the concentration of the (meth)acrylic resin reached 35% by mass, and the temperature was maintained at this level for 12 hours from the start of ethyl acetate addition. Finally, ethyl acetate was added to adjust the concentration of the (meth)acrylic resin to 20% by mass, and an ethyl acetate solution of the (meth)acrylic resin was prepared.

[0148] [Measurement of glass transition temperature (Tg) of (meth)acrylic resins] The glass transition temperature (Tg) of (meth)acrylic resins was measured using a differential scanning calorimeter (DSC) "EXSTAR DSC6000" manufactured by SII Nanotechnology Co., Ltd., under a nitrogen atmosphere, with a measurement temperature range of -80 to 50°C and a heating rate of 10°C / min. The results are shown in Table 1.

[0149] [Measurement of weight-average molecular weight and number-average molecular weight of (meth)acrylic resins] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of (meth)acrylic resins were measured using a GPC apparatus with five columns in series: four "TSKgel XL" columns manufactured by Tosoh Corporation and one "Shodex GPC KF-802" column manufactured by Showa Denko K.K. and sold by Shoko Tsusho Co., Ltd. Tetrahydrofuran was used as the eluent. The measurements were taken in standard polystyrene equivalents under the following conditions: sample concentration of 5 mg / mL, sample introduction volume of 100 μL, temperature of 40°C, and flow rate of 1 mL / min. The results are shown in Table 1.

[0150] [Table 1] The abbreviations in the "Monomer Composition" column of Table 1 refer to the following monomers: BA: Butyl acrylate (butyl acrylate) MA: Methyl acrylate (methyl acrylate) PEA: 2-phenoxyethyl acrylate HEA: 2-Hydroxyethyl acrylate (2-hydroxyethyl acrylate) AA: Acrylic acid

[0151] [Examples 1-11, Comparative Examples 1-3] (1) Preparation of adhesive composition To 100 parts of the solids content of the (meth)acrylic resin obtained in Production Example 1, a crosslinking agent, a silane compound, and an ionic compound were mixed in the amounts [parts by mass] shown in Table 2. Ethyl acetate was then added to achieve a solids content concentration of 14% by mass to prepare a solution of the adhesive composition. In Table 2, the amounts [parts by mass] of the crosslinking agent, silane compound, and ionic compound are expressed on a solids basis.

[0152] [Table 2] Each ingredient in Table 2 refers to the following compound: [Crosslinking agent] Crosslinking agent (B) (equivalent to aromatic isocyanate crosslinking agent (B1)): Coronate L (ethyl acetate solution of trimethylolpropane adduct of tolylene diisocyanate: solid content concentration 75% by mass), manufactured by Tosoh Corporation. [Silane compounds] Silane compound (C1-1) (equivalent to mercapto group-containing silane compound (C1)): Mercapto group-containing silicone oligomer "KR-519" (mercapto equivalent 450 g / mol), manufactured by Shin-Etsu Chemical Co., Ltd. Silane compound (C1-2) (equivalent to mercapto group-containing silane compound (C1)): 3-mercaptopropyltrimethoxysilane "KBM-803" (molecular weight 196.34), manufactured by Shin-Etsu Chemical Co., Ltd. Silane compound (C2-1) (equivalent to epoxy group-containing silane compound (C2)): 3-Glycidoxypropyltrimethoxysilane "KBM-403" (molecular weight 236.34), manufactured by Shin-Etsu Chemical Co., Ltd. Silane compound (C2-2) (equivalent to epoxy group-containing silane compound (C2)): 8-Glycidoxyoctyltrimethoxysilane "KBM-4803" (molecular weight 306.47), manufactured by Shin-Etsu Chemical Co., Ltd. Silane compound (C2-3) (equivalent to epoxy group-containing silane compound (C2)): 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane "KBM-303" (molecular weight 246.38), manufactured by Shin-Etsu Chemical Co., Ltd. Silane compound (C2-4) (equivalent to epoxy group-containing silane compound (C2)): Epoxy group-containing silicone oligomer "KR-517" (epoxy equivalent 830 g / mol), manufactured by Shin-Etsu Chemical Co., Ltd. [Ionic compounds] Ionic compound (D): N-hexyl-4-methylpyridinium hexafluoride phosphorus (60% toluene solution)

[0153] (2) Preparation of the adhesive layer The adhesive composition prepared in (1) above was applied using an applicator to the release-treated surface of a separator film made of polyethylene terephthalate film that had been subjected to a release treatment [PLR-382190 obtained from Lintec Corporation], so that the thickness after drying was 20 μm, and an adhesive layer (adhesive sheet) was prepared by drying at 100°C for 1 minute.

[0154] [Measurement of gel fraction] The gel fraction [gel fraction at 23°C (G23)] was measured for the adhesive layer (adhesive sheet) that was left at 23°C for 5 days immediately after obtaining it. The gel fraction was measured according to the following [a] to [d]. The results are shown in Table 3. [a] A bonding layer with an area of ​​approximately 8 cm x 8 cm is attached to a metal mesh made of SUS304 with an area of ​​approximately 10 cm x 10 cm (its mass is Wm). [b] Weigh the laminate obtained in [a] above, and let its mass be Ws. Then, fold it four times so as to enclose the adhesive layer, fasten it with a stapler, and weigh it again, letting its mass be Wb. [c] Place the mesh stapled in [b] above into a glass container, add 60 mL of ethyl acetate and immerse in it, then store the glass container at room temperature for 3 days. [d] Remove the mesh from the glass container, dry it at 120°C for 4 hours, and then weigh it. Let its mass be Wa. Formulate the following: The gel fraction (mass%) is calculated based on the formula: Gel fraction (mass%) = [{Wa-(Wb-Ws)-Wm} / (Ws-Wm)] × 100.

[0155] (3) Fabrication of polarizing plates A polarizer was fabricated by laminating a 23 μm thick polarizer, on which iodine was adsorbed and oriented on a uniaxially oriented polyvinyl alcohol film, with a 75 μm thick protective film made of (meth)acrylic resin on one side and a 50 μm thick protective film as a phase difference film made of cyclic polyolefin resin on the other side, via an active energy ray curable adhesive.

[0156] (4) Fabrication of polarizing plates with adhesive layer The side of the adhesive layer prepared in (2) above that is opposite to the separator film (the adhesive layer side) was laminated to the outer surface of the polarizing plate, which is made of a cyclic polyolefin resin, using a laminator. After curing at a temperature of 23°C and a relative humidity of 65%RH for 5 days, a polarizing plate with an adhesive layer was obtained.

[0157] (5) Evaluation [Evaluation of the release properties of the separator film] The polarizing plate with adhesive layer obtained in (4) above was cut to a size of 120 mm x 25 mm so that the absorption axis of the polarizer was on the longer side. A 120 mm x 25 mm double-sided tape (Nicetack (product name), manufactured by Nichiban Co., Ltd.) was attached to an alkali-free glass substrate (Eagle XG, manufactured by Corning). Then, this double-sided tape was bonded to the polarizing plate side of the polarizing plate with adhesive layer obtained in (4) above, and a test piece (a polarizing plate with adhesive layer to which a glass substrate is attached) with the separator film on the outermost surface was prepared. In this state, using an Autograph (AGS-50NX, manufactured by Shimadzu Corporation), one end of the separator film in the longitudinal direction (one side with a width of 5 cm) was grasped, and under conditions of a temperature of 23°C and a humidity of 55%RH, it was pulled in the 180° direction at a peeling speed of 300 mm / min to peel it off from the adhesive layer, and the peeling force at that time was recorded. Since the data is unstable immediately after the start and immediately after the end of measurement, 20% of the data after the start and 20% after the end of measurement were cut, and the average value was calculated from only the relatively stable middle 60% range, which was taken as the peeling force [N / 25mm] of the separator film.

[0158] [Evaluation of adhesion] (Sample preparation) The polarizing plate with adhesive layer obtained in (4) above was cut to a size of 150 mm x 25 mm so that the absorption axis of the polarizer was on the longer side. The separator film was peeled off the cut polarizing plate with adhesive layer, and the exposed adhesive layer was bonded to the center of an alkali-free glass substrate [Corning's "Eagle XG"] measuring 160 mm in length, 50 mm in width, and 0.7 mm in thickness. The resulting test piece with the glass substrate attached (polarizing plate with adhesive layer and glass substrate attached) was then autoclaved at a temperature of 50°C and a pressure of 5 kgf / cm². 2 The sample was prepared by pressurizing it at 490.3 kPa for 20 minutes.

[0159] (Measurement of adhesion strength at a temperature of 23°C) The above samples were stored for 24 hours in an environment of 23°C and 55% RH relative humidity. Then, a cutter blade was inserted between the glass substrate and the adhesive layer, and 30 mm was peeled from the edge in the longitudinal direction. This peeled portion was then gripped by the gripping section of a universal tensile testing machine (product name "AGS-50NX" manufactured by Shimadzu Corporation). The test specimen in this state was subjected to a 180-degree peel test in an atmosphere of 23°C and 55% RH relative humidity, according to JIS K 6854-2:1999 "Adhesives - Test methods for peel strength - Part 2: 180-degree peel" at a gripping speed of 300 mm / min. The average peel force over a length of 120 mm excluding the 30 mm gripping section was calculated and defined as the adhesion force at 23°C. The results are shown in Table 3.

[0160] (Measurement of adhesion strength and observation of the glass substrate surface after being left in a humid, heat-sensitive environment) The above samples were stored for 240 hours in a humidified thermal atmosphere at a temperature of 60°C and a relative humidity of 90%RH. Then, a cutter blade was inserted between the glass substrate and the adhesive layer, and 30mm of the sample was peeled from the edge in the longitudinal direction. This peeled portion was then gripped by the gripping section of a universal tensile testing machine (product name "AGS-50NX" manufactured by Shimadzu Corporation). The test specimen in this state was subjected to a 180° peel test in an atmosphere of 23°C and a relative humidity of 55%RH, according to JIS K 6854-2:1999 "Adhesives - Test methods for peel strength - Part 2: 180° peel" at a gripping speed of 300mm / min. The average peel force over a length of 120mm excluding the 30mm gripping section was calculated and defined as the adhesion force after being left in the humidified thermal environment. The results are shown in Table 3.

[0161] From the viewpoint of reworkability, it is preferable that the adhesion strength after being left in a humid, heat-sensitive environment is 20 N / 25 mm or less. Furthermore, it is preferable that the difference between the measured adhesion strength after being left in a humid, heat-sensitive environment and the adhesion strength at 23°C is 18 N / 25 mm or less.

[0162] The glass substrate surface was visually inspected after a 180-degree peel test following exposure to a humidified heat environment, and the glass appearance was evaluated according to the following criteria. From the viewpoint of reworkability, an evaluation result of A to C is preferable. The results are shown in Table 3. A: Almost no clouding or adhesive residue is observed on the surface of the glass substrate. B: There is almost no adhesive residue on the glass substrate surface, but cloudiness is observed. C: Some adhesive residue is observed on the surface of the glass substrate. D: Adhesive residue is observed across the entire surface of the glass substrate.

[0163] [Evaluation of antistatic properties] After peeling the separator film from the polarizing plate with adhesive layer prepared in (4) above, the surface resistance of the adhesive layer was measured using a surface resistivity measuring device [Mitsubishi Chemical Corporation's "Highresta-up MCP-HT450" (product name)]. The measurement conditions were an applied voltage of 100V and an applied time of 30 seconds.

[0164] [Durability evaluation] After peeling the separator film from the polarizing plate with adhesive layer prepared in (4) above, the adhesive layer surface was attached to both sides of an alkali-free glass substrate [Corning's "Eagle XG"] in a cross-nicol configuration to prepare an evaluation sample. Heat resistance tests and thermal shock tests were performed using this evaluation sample.

[0165] (Heat resistance test) A heat resistance test was conducted on the evaluation samples, holding them under dry conditions at a temperature of 80°C for 500 hours.

[0166] (Heat shock (HS) test) A heat shock (HS) test was conducted by holding the evaluation sample at a temperature of 70°C under dry conditions for 30 minutes, followed by holding it at -40°C under dry conditions for 30 minutes. This cycle was repeated 200 times.

[0167] After each heat resistance test and HS test, evaluation samples were visually inspected for lifting and peeling at the interface between the adhesive layer and the glass substrate, as well as for foaming of the adhesive layer. Durability was then evaluated according to the following evaluation criteria. The results are shown in Table 3. A: Some changes in appearance such as lifting, peeling, and foaming are observed. B: Significant changes in appearance such as lifting, peeling, and foaming are observed. C: Significant changes in appearance such as lifting, peeling, and foaming are observed.

[0168] [Table 3] [Explanation of symbols]

[0169] 1 optical film with adhesive layer, 10 optical films, 12 polarizers, 13 protective film, 14 protective film, 20 adhesive layers.

Claims

1. An adhesive composition containing a (meth)acrylic resin (A), a crosslinking agent (B), and a silane compound (C), The silane compound (C) includes a mercapto group-containing silane compound (C1) and an epoxy group-containing silane compound (C2). The content of the mercapto group-containing silane compound (C1) is greater than the content of the epoxy group-containing silane compound (C2), and is between 0.3 parts by mass and 8 parts by mass per 100 parts by mass of the (meth)acrylic resin (A). The content of the epoxy group-containing silane compound (C2) is 0.01 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the (meth)acrylic resin (A), in an adhesive composition.

2. The adhesive composition according to claim 1, wherein the (meth)acrylic resin (A) has a weight-average molecular weight of 1 million or more, a glass transition temperature of -45°C or higher, and contains constituent units derived from (meth)acrylate having hydroxyl groups.

3. The adhesive composition according to claim 1 or 2, wherein the (meth)acrylic resin (A) further contains a constituent unit derived from an alkyl acrylate (a1) whose homopolymer glass transition temperature is less than 0°C, and a constituent unit derived from an alkyl acrylate (a2) whose homopolymer glass transition temperature is 0°C or higher.

4. The adhesive composition according to any one of claims 1 to 3, wherein the (meth)acrylic resin (A) further contains a constituent unit derived from an unsaturated monomer having one olefinic double bond and at least one aromatic ring in its molecule.

5. The adhesive composition according to any one of claims 1 to 4, wherein the (meth)acrylic resin (A) further contains constituent units derived from (meth)acrylic acid.

6. The aforementioned crosslinking agent (B) includes an aromatic isocyanate crosslinking agent (B1), The adhesive composition according to any one of claims 1 to 5, wherein the content of the aromatic isocyanate crosslinking agent (B1) is 0.1 parts by mass or more and 4.5 parts by mass or less per 100 parts by mass of the (meth)acrylic resin (A).

7. Furthermore, the adhesive composition according to any one of claims 1 to 6, further containing an ionic compound (D).

8. An adhesive layer comprising the adhesive composition according to any one of claims 1 to 7.

9. An optical film with an adhesive layer, comprising an optical film and an adhesive layer according to claim 8 laminated on at least one surface thereof.

10. The optical film with an adhesive layer according to claim 9, wherein the optical film comprises a polarizer and a protective film laminated on at least one surface thereof.

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