Adhesive composition, adhesive film, polarizing plate with an adhesive layer, and liquid crystal panel

Abstract

To provide an adhesive composition, an adhesive film, a polarizing plate with an adhesive layer, and a liquid crystal panel, which enable excellent antistatic performance with the surface resistivity of the adhesive layer being 9.0×10+10 Ω / sq. or less, without compromising its durability.SOLUTION: An adhesive composition comprises an acrylic polymer derived from the copolymerization of (A) n-butylacrylate, (B) at least one selected from t-butylacrylate, isobutyl acrylate, n-butyl methacrylate, and methyl acrylate, (C) a copolymerizable vinyl monomer with a hydroxy group and / or a carboxyl group, and (D) a copolymerizable vinyl monomer with an aromatic group, (E) an ammonium-based antistatic agent with a fluoro group-bearing anion, (F) a crosslinker selected from isocyanate compounds with three or more functionalities and epoxy compounds with two or more functionalities, and (G) a silane coupling agent with a functional group selected from epoxy groups, mercapto groups, and acid anhydride groups.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an adhesive composition and an adhesive film that can be used, for example, in an application where the adherend is a liquid crystal panel and is bonded to an in-cell panel incorporating a touch panel function. In particular, the present invention relates to an adhesive composition having extremely excellent antistatic performance with a surface resistivity of the adhesive layer of 9.0×10 +10 Ω / □ or less, and an adhesive film using the same.

Background Art

[0002] Various adhesive films have been proposed for bonding optical members such as polarizing plates and retardation plates to an adherend such as a liquid crystal cell via an adhesive layer (see, for example, Patent Documents 1 and 2). Patent Document 1 describes an optical adhesive composition containing an acrylic polymer obtained by copolymerizing a monomer mainly composed of butyl acrylate or the like and an acrylamide compound or the like. Patent Document 2 describes an optical adhesive composition containing an acrylic polymer obtained by copolymerizing a monomer mainly composed of (meth)acrylate having an alkyl group having 4 to 8 carbon atoms, a carboxyl group-containing monomer, and a nitrogen-containing vinyl monomer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the adhesive layer for bonding a polarizing plate and a liquid crystal panel, when the liquid crystal panel is an in-cell panel incorporating the function of a touch panel, it is required that the surface resistivity of the adhesive layer be set to a value lower than the conventional surface resistivity. For this reason, for the adhesive layer used to bond a polarizing plate to a liquid crystal panel, it is desired that the surface resistivity of the adhesive layer be 9.0×10 +10 Ω / □ or less. However, in the prior art, it has been very difficult to achieve such a high level of antistatic performance. Moreover, even when such a high level of antistatic performance could be achieved, it was difficult to maintain the durability of the adhesive layer at the same time.

[0005] An object of the present invention is to provide an adhesive composition having extremely excellent antistatic performance with a surface resistivity of 9.0×10 +10 Ω / □ or less and not impairing durability, and an adhesive film using the same.

Means for Solving the Problems

[0006] As a result of intensive efforts by the present inventors to solve the difficult problem of simultaneously achieving both such a high level of antistatic performance and durability, the number of carbon atoms in the alkyl group of the alkyl (meth) acrylate constituting the acrylic polymer of the adhesive composition is limited to a specific range, and an acrylic polymer composed of a copolymer obtained by copolymerizing two or more kinds of alkyl (meth) acrylates in a specific combination is used. Furthermore, by using an adhesive composition containing a specific antistatic agent, it has become possible to solve this problem.

[0007] The present inventors have found that by containing an ammonium-based antistatic agent having a fluoro group-containing anion in an amount of 2.5 to 15 parts by weight with respect to 100 parts by weight of the acrylic polymer, an adhesive composition having extremely excellent antistatic performance compared to conventional adhesive compositions, and having excellent durability without precipitation of the antistatic agent and without deterioration over time can be obtained, and thus completed the present invention.

[0008] The pressure-sensitive adhesive composition according to the present invention contains, relative to 100 parts by weight of an acrylic polymer, 2.5 to 15 parts by weight of an ammonium-based antistatic agent having a fluorine group-containing anion in order to achieve extremely excellent antistatic performance with a surface resistivity of the pressure-sensitive adhesive layer of 9.0×10 +10 Ω / □ or less. Thus, in the present invention, the content of the antistatic agent is increased in order to obtain extremely excellent antistatic performance. Therefore, after the durability test of the pressure-sensitive adhesive layer under high-temperature and high-humidity environments, the ammonium-based antistatic agent having a fluorine group-containing anion contained in a large amount in the pressure-sensitive adhesive layer does not precipitate on the surface of the pressure-sensitive adhesive layer, and the acrylic polymer contained in the pressure-sensitive adhesive composition is mainly composed of n-butyl acrylate (BA), and the technical idea is to select a monomer having good copolymerizability with BA and copolymerize them to form a pressure-sensitive adhesive layer capable of maintaining durability.

[0009] Also, to solve the above problems, the present invention provides a pressure-sensitive adhesive composition containing an acrylic polymer, an antistatic agent, and a crosslinking agent, wherein the acrylic polymer is a copolymer obtained by copolymerizing (A) n-butyl acrylate, (B) at least one selected from the group consisting of t-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, and methyl acrylate, (C) at least one copolymerizable vinyl monomer containing a hydroxyl group and / or a carboxyl group, and (D) at least one copolymerizable vinyl monomer containing an aromatic group, and the weight average molecular weight of the copolymer is 1,000,000 to 3,000,000; as the (E) antistatic agent, an ammonium-based antistatic agent having a fluorine group-containing anion is contained in a proportion of 2.5 to 15 parts by weight with respect to 100 parts by weight of the acrylic polymer; as the (F) crosslinking agent, at least one crosslinking agent selected from the group consisting of trifunctional or higher isocyanate compounds and bifunctional or higher epoxy compounds is contained; the pressure-sensitive adhesive composition further contains (G) a monomer-type or oligomer-type silane coupling agent containing at least one functional group selected from the group consisting of an epoxy group, a mercapto group, and an acid anhydride group; the surface resistivity of the pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition is 9.0×10 +10 Ω / □ or less, and after subjecting the pressure-sensitive adhesive layer to a durability test in a test environment of 85°C×750 hr or in a test environment of 60°C×90%RH×750 hr, no precipitation of the antistatic agent occurs on the surface of the pressure-sensitive adhesive layer.

[0010] Also, the antistatic agent is an ionic compound having a melting point of 25°C or higher and consisting of a fluorine group-containing anion and an ammonium cation, and the fluorine group-containing anion is preferably one selected from the group consisting of pentafluorobenzenesulfonate, hexafluorophosphate, bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide, and triflate.

[0011] The acrylic polymer contains 40 to 89 parts by weight of the (A) n-butyl acrylate and a total of 5 to 40 parts by weight of at least one selected from the group consisting of the (B) t-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, and methyl acrylate, based on 100 parts by weight of the acrylic polymer, and the ratio (A) / (B) of (A) to (B) is preferably 1.0 to 17.8.

[0012] When a polarizing plate with a total thickness of 80 μm is bonded to non-alkali glass via an adhesive layer with a thickness of 20 μm obtained by crosslinking the adhesive composition, the adhesive force of the adhesive layer to the non-alkali glass is 1.0 to 6.0 N / 25 mm. After a test piece obtained by bonding a 10 cm square polarizing plate with a total thickness of 80 μm to non-alkali glass via an adhesive layer with a thickness of 20 μm obtained by crosslinking the adhesive composition is subjected to a durability test in a test environment of 85°C × 750 hr, or after being subjected to a durability test in a test environment of 60°C × 90% RH × 750 hr, it is preferable that there is no foaming or peeling.

[0013] The copolymerizable vinyl monomer containing the (C) hydroxyl group and / or carboxyl group is at least one selected from the group consisting of copolymerizable monomers containing a hydroxyl group and copolymerizable monomers containing a carboxyl group, and is contained in a proportion of 0.1 to 5 parts by weight based on a total of 100 parts by weight of the (A), the (B), and the (D). The copolymerizable monomer containing a hydroxyl group is at least one selected from the group consisting of compounds such as 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxyethyl (meth)acrylamide. The copolymerizable monomer containing a carboxyl group is preferably at least one selected from the group consisting of compounds such as (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl maleic acid, carboxypolycaprolactone mono (meth)acrylate, and 2-(meth)acryloyloxyethyl tetrahydrophthalic acid.

[0014] It is preferable that both the initial surface resistivity of the pressure-sensitive adhesive layer and the surface resistivity after being subjected to the durability test in a test environment of 85 °C × 750 hr are 9.0×10 +10 Ω / square or less.

[0015] The present invention also provides a pressure-sensitive adhesive film characterized in that a pressure-sensitive adhesive layer obtained by crosslinking the above pressure-sensitive adhesive composition is laminated on one side of a resin film.

[0016] The present invention also provides a pressure-sensitive adhesive film for a polarizing plate, which uses the above pressure-sensitive adhesive film.

[0017] The present invention also provides the above-mentioned pressure-sensitive adhesive film for a polarizing plate, which is used for bonding the polarizing plate and the in-cell panel.

[0018] The present invention also provides a pressure-sensitive adhesive film characterized in that a pressure-sensitive adhesive layer obtained by crosslinking the above-mentioned pressure-sensitive adhesive composition is formed on one side of a release film with a thickness of 1 μm to 25 μm, and has a structure of release film / pressure-sensitive adhesive layer / release film.

[0019] The present invention also provides an optical film with a pressure-sensitive adhesive layer, characterized in that a pressure-sensitive adhesive layer obtained by crosslinking the above-mentioned pressure-sensitive adhesive composition is laminated on at least one surface of the optical film, and has a structure of release film / pressure-sensitive adhesive layer / optical film.

[0020] The present invention also provides a polarizing plate with a pressure-sensitive adhesive layer, characterized in that a pressure-sensitive adhesive layer obtained by crosslinking the above-mentioned pressure-sensitive adhesive composition is laminated on one side of the polarizing plate, and has a structure of release film / pressure-sensitive adhesive layer / polarizing plate.

[0021] The present invention also provides a liquid crystal panel characterized in that the above-mentioned polarizing plate with a pressure-sensitive adhesive layer is used.

[0022] The present invention also provides an in-cell type liquid crystal panel characterized in that the above-mentioned polarizing plate with a pressure-sensitive adhesive layer is used.

Effects of the Invention

[0023] According to the present invention, it is possible to provide a pressure-sensitive adhesive composition having extremely excellent antistatic performance with a surface resistivity of the pressure-sensitive adhesive layer of 9.0×10 +10 Ω / □ or less and not impairing durability, and a pressure-sensitive adhesive film using the same.

Embodiments for Carrying Out the Invention

[0024] Hereinafter, the present invention will be described based on preferred embodiments.

[0025] The pressure-sensitive adhesive composition of this embodiment is a pressure-sensitive adhesive composition containing an acrylic polymer, an antistatic agent, and a crosslinking agent, wherein the acrylic polymer is a copolymer obtained by copolymerizing (A) n-butyl acrylate, (B) at least one selected from the group consisting of t-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, and methyl acrylate, (C) at least one copolymerizable vinyl monomer containing a hydroxyl group and / or a carboxyl group, and (D) at least one copolymerizable vinyl monomer containing an aromatic group, and the acrylic polymer has a weight average molecular weight of 1,000,000 to 3,000,000. As the (E) antistatic agent, an ammonium-based antistatic agent having a fluorine group-containing anion is contained in a proportion of 2.5 to 15 parts by weight based on 100 parts by weight of the acrylic polymer. As the (F) crosslinking agent, the pressure-sensitive adhesive composition contains at least one crosslinking agent selected from the group consisting of trifunctional or higher isocyanate compounds and bifunctional or higher epoxy compounds. The pressure-sensitive adhesive composition further contains (G) a monomer type or oligomer type silane coupling agent containing at least one functional group selected from an epoxy group, a mercapto group, and an acid anhydride group. The surface resistivity of the pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition is 9.0×10 +10 Ω / □ or less, and after subjecting the pressure-sensitive adhesive layer to a durability test in a test environment of 85°C × 750 hr or after subjecting the pressure-sensitive adhesive layer to a durability test in a test environment of 60°C × 90% RH × 750 hr, the antistatic agent does not precipitate on the surface of the pressure-sensitive adhesive layer.

[0026] (A) n-butyl acrylate and (B) at least one selected from the group consisting of t-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, and methyl acrylate all correspond to alkyl (meth)acrylate monomers. In the pressure-sensitive adhesive composition of this embodiment, it is preferable that the monomers of alkyl (meth)acrylate constituting the acrylic polymer are a combination of specific two or more types, namely (A) and (B).

[0027] The acrylic polymer of this embodiment is mainly composed of (A) n-butyl acrylate. For example, it is preferably contained in a proportion of 40 to 89 parts by weight of (A) n-butyl acrylate with respect to 100 parts by weight of the acrylic polymer. Further, as an alkyl (meth) acrylate monomer other than (A) n-butyl acrylate, the acrylic polymer preferably contains at least one selected from the group consisting of (B) t-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, and methyl acrylate in a total proportion of 5 to 40 parts by weight. And the ratio (A) / (B) of (A) to (B) is preferably 1.0 to 17.8 as a weight ratio.

[0028] (C) As the copolymerizable vinyl monomer containing a hydroxyl group and / or a carboxyl group, at least one selected from the group consisting of a copolymerizable monomer containing a hydroxyl group (hydroxyl group-containing monomer) and a copolymerizable monomer containing a carboxyl group (carboxyl group-containing monomer) can be mentioned. That is, only one of the hydroxyl group-containing monomer or the carboxyl group-containing monomer may be selected for copolymerization, or both the hydroxyl group-containing monomer and the carboxyl group-containing monomer may be copolymerized. The proportion of the copolymerizable vinyl monomer (C) containing a hydroxyl group and / or a carboxyl group is preferably 0.1 to 5 parts by weight with respect to 100 parts by weight in total of (A), (B), and (D). Note that (A), (B), and (D) are all vinyl monomers that do not contain a hydroxyl group and a carboxyl group.

[0029] Examples of the hydroxyl group-containing monomer include at least one of hydroxyalkyl (meth) acrylates such as 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, and hydroxyl group-containing (meth) acrylamides such as N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide. In addition, the hydroxyl group-containing monomer to be incorporated into the pressure-sensitive adhesive composition according to the present embodiment can be used as a copolymerizable monomer for reducing the content of the carboxyl group-containing monomer, which is considered to affect the corrosiveness of the resulting pressure-sensitive adhesive layer against a substrate prone to corrosion such as the ITO surface of a transparent conductive film. Therefore, the hydroxyl group-containing monomer can be used to improve the adhesive strength of the pressure-sensitive adhesive layer and reduce the corrosiveness. The proportion of the hydroxyl group-containing monomer to be incorporated into the pressure-sensitive adhesive composition of the present embodiment is preferably 0.1 to 5.0 parts by weight, more preferably 0.1 to 4.4 parts by weight, and particularly preferably 0.1 to 3.8 parts by weight, based on 100 parts by weight in total of (A), (B), and (D).

[0030] Examples of the carboxyl group-containing monomer include at least one or more of (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl maleic acid, carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyl tetrahydrophthalic acid, and the like. In addition, the carboxyl group-containing monomer to be incorporated into the pressure-sensitive adhesive composition according to the present embodiment can impart the necessary cohesive force to the resulting pressure-sensitive adhesive layer. The proportion of the carboxyl group-containing monomer in the pressure-sensitive adhesive composition according to the present embodiment is preferably 0 to 5.0 parts by weight, based on 100 parts by weight in total of (A), (B), and (D). When copolymerizing a hydroxyl group-containing monomer with an acrylic polymer, it is also acceptable not to copolymerize a carboxyl group-containing monomer. When copolymerizing a carboxyl group-containing monomer, the proportion is more preferably 0.01 to 5.0 parts by weight, particularly preferably 0.01 to 3.3 parts by weight, and most preferably 0.01 to 2.8 parts by weight.

[0031] (D) Examples of the copolymerizable vinyl monomer containing an aromatic group include at least one or more of benzyl (meth)acrylate, naphthyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxybutyl (meth)acrylate, 2-(1-naphthyloxy)ethyl (meth)acrylate, 2-(2-naphthyloxy)ethyl (meth)acrylate, 6-(1-naphthyloxy)hexyl (meth)acrylate, 6-(2-naphthyloxy)hexyl (meth)acrylate, 8-(1-naphthyloxy)octyl (meth)acrylate, 8-(2-naphthyloxy)octyl (meth)acrylate, etc. When the copolymerizable vinyl monomer containing an aromatic group contains a (meth)acrylate monomer containing an aromatic group, it is preferable because it has excellent copolymerizability with the alkyl (meth)acrylate monomer composed of the combination of (A) and (B).

[0032] In order to obtain an adhesive layer with a high refractive index, it is preferable to blend at least one or more (meth)acrylate monomers containing an aromatic group in the adhesive composition according to this embodiment. By copolymerizing these (meth)acrylate monomers containing an aromatic group with an acrylic polymer, the refractive index of the obtained adhesive layer can be increased and adjusted, the refractive index difference between optical members can be reduced, and total internal reflection can be reduced to improve the total light transmittance. In the adhesive composition according to this embodiment, the (meth)acrylate monomer containing an aromatic group is preferably contained in a proportion of 5 to 30 parts by weight, more preferably 6 to 28 parts by weight, and particularly preferably 6 to 24 parts by weight based on 100 parts by weight of the acrylic polymer.

[0033] The production method of the acrylic polymer to be contained in the adhesive composition according to this embodiment is not particularly limited, and known polymerization methods such as solution polymerization method and emulsion polymerization method can be appropriately used. The weight average molecular weight of the copolymer of the acrylic polymer is preferably 1 million to 3 million.

[0034] The pressure-sensitive adhesive composition according to this embodiment contains (E) an antistatic agent in order to obtain antistatic performance. As the (E) antistatic agent, it is preferable that an ammonium-based antistatic agent having a fluorine group-containing anion is contained in a proportion of 2.5 to 15 parts by weight, more preferably 3 to 15 parts by weight, and particularly preferably 4 to 15 parts by weight with respect to 100 parts by weight of the acrylic polymer. This antistatic agent is an ionic compound composed of a fluorine group-containing anion and an ammonium cation. This ionic compound is an ionic compound having a melting point of 25°C or higher, and is preferably a solid at room temperature (for example, 25°C). Further, it is more preferable that this ionic compound is an ionic compound having a melting point of 25°C to 80°C and being a solid at a temperature of 25°C.

[0035] Examples of the fluorine group-containing anion contained in the (E) antistatic agent include inorganic or organic fluorine group-containing anions. Here, the fluorine group means a fluorine atom bonded to other atoms constituting the anion. Examples of the inorganic fluorine group-containing anion include PF6 - , AsF6 - , SbF6 - , BF4 - , AlF4 - , (FSO2)2N - , FSO3 - , and the like. Examples of the organic fluorine group-containing anion include fluorine group-containing sulfonate anions (RSO3 - ), fluorine group-containing carboxylate anions (RCOO - ), fluorine group-containing alkoxides or phenoxides anions (RO - ), fluorine group-containing organic imide anions (R2N - ), fluorine group-containing methide (R3C - ) anions, fluorine group-containing organic borates (R4B -)Examples of the anion include an anion having an organic group containing a fluoro group as at least one of R with anions or the like. Examples of the organic group include one or more of an alkyl group, an alkoxy group, an aromatic group (aryl group, aralkyl group, etc.), an alkylcarbonyl group, an aromatic carbonyl group, an alkylsulfonyl group, an aromatic sulfonyl group, and the like. When the anion has two or more Rs, a bond may be formed between the two or more Rs to form a cyclic structure. Among them, it is preferably one selected from the group consisting of pentafluorobenzenesulfonate, hexafluorophosphate, bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide, and triflate.

[0036] (E)Examples of the ammonium cation contained in the antistatic agent include an organic ammonium cation having 1 to 4 organic groups, and particularly a quaternary ammonium cation (R4N + ) is preferable. Examples of R include hydrocarbon groups such as acyclic or cyclic alkyl groups and aromatic groups (aryl groups, aralkyl groups, etc.). When the cation has two or more Rs, a bond may be formed between the two or more Rs to form a cyclic structure.

[0037] The pressure-sensitive adhesive composition according to the present embodiment further contains (F) at least one crosslinking agent selected from the group consisting of a polyfunctional isocyanate compound having three or more functional groups and an epoxy compound having two or more functional groups as a crosslinking agent. Examples of the ratio of the (F) crosslinking agent include a ratio of 0.01 to 5 parts by weight with respect to 100 parts by weight of the acrylic polymer.

[0038] Examples of the polyfunctional isocyanate compound having three or more functional groups include biuret-modified products and isocyanurate-modified products of diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, and xylylene diisocyanate, and adducts with polyols having trivalent or higher valences such as trimethylolpropane and glycerin. Examples of the epoxy compound having two or more functional groups include diglycidyl ethers of glycols, diglycidyl ethers of bisphenols, triglycidyl ethers of triols, diglycidyl esters of dicarboxylic acids, diglycidyl-substituted amines, tetraglycidyl-substituted diamines, and the like.

[0039] The pressure-sensitive adhesive composition according to this embodiment further contains (G) a silane coupling agent. Examples of the (G) silane coupling agent include compounds having at least one organic functional group and at least one hydrolyzable group in one molecule, and the hydrolyzable group is an alkoxy group bonded to a silicon atom. The (G) silane coupling agent contains at least one or more functional groups selected from an epoxy group, a mercapto group, and an acid anhydride group. As the (G) silane coupling agent, one or both of a monomer type and an oligomer type can be used in at least one or more kinds. The ratio of the silane coupling agent is, for example, 0.01 to 0.5 parts by weight with respect to 100 parts by weight of the acrylic polymer.

[0040] Examples of the silane coupling agent having an epoxy group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 5,6-epoxyhexyltrimethoxysilane, 5,6-epoxyhexylmethyldimethoxysilane, 5,6-epoxyhexylmethyldiethoxysilane, 5,6-epoxyhexyltriethoxysilane, and the like. Examples of the silane coupling agent having a mercapto group include 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-mercaptopropyltriethoxysilane, and the like. Examples of the silane coupling agent having an acid anhydride group include 3-trimethoxysilylpropyl succinic anhydride, 3-triethoxysilylpropyl succinic anhydride, and the like. Further, oligomerized alkoxy oligomers (silicone alkoxy oligomers) and the like can also be used as the silane coupling agent.

[0041] As optional components, the pressure-sensitive adhesive composition of the present embodiment can be appropriately blended with known additives such as antioxidants, surfactants, curing accelerators, plasticizers, fillers, crosslinking catalysts, crosslinking retardants, curing retardants, processing aids, anti-aging agents, and the like. These may be used alone or in combination of two or more.

[0042] The surface resistivity of the pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition of the present embodiment is preferably +10 9.0×10 +10 Ω / □ or less, more preferably +10It is particularly preferable that it is 9.0×10 +10 Ω / square or less. It is preferable that both the initial surface resistivity and the surface resistivity after the durability test of this adhesive layer are 9.0×10 +10 Ω / square or less, more preferably 5.0×10 +10 Ω / square or less, and particularly preferably 2.0×10

[0043] The adhesive layer obtained by crosslinking the adhesive composition of the present embodiment does not have (E) antistatic agent precipitated on the surface of the adhesive layer after being subjected to the durability test in a test environment of 85°C×750 hr and the durability test in a test environment of 60°C×90%RH×750 hr. Here, the test environment of 85°C×750 hr may be a dry condition. The precipitation prevention performance of the (E) antistatic agent in the adhesive composition of the present embodiment is such that two or more samples of the adhesive layer obtained by crosslinking the same adhesive composition are prepared, and after one sample is subjected to the durability test in a test environment of 85°C×750 hr, the (E) antistatic agent does not precipitate, and after another sample is subjected to the durability test in a test environment of 60°C×90%RH×750 hr, the (E) antistatic agent may not precipitate.

[0044] When the adhesive layer obtained by crosslinking the adhesive composition of the present embodiment bonds a polarizing plate with a total thickness of 80 μm to non-alkali glass through an adhesive layer with a thickness of 20 μm, it is preferable that the adhesive force of the adhesive layer to the non-alkali glass is 1.0 to 6.0 N / 25 mm. In addition, after a test piece obtained by bonding a polarizing plate with a total thickness of 80 μm and a size of 10 cm square to non-alkali glass through an adhesive layer with a thickness of 20 μm is subjected to the durability test in a test environment of 85°C×750 hr and the durability test in a test environment of 60°C×90%RH×750 hr, it is preferable that there is no foaming or peeling. In the pressure-sensitive adhesive composition of this embodiment, the performance of no foaming and no peeling can be such that after preparing two or more test pieces made using the same pressure-sensitive adhesive composition, and subjecting one test piece to a durability test in a test environment of 85°C × 750 hr, there is no foaming or peeling, and even when another test piece is subjected to a durability test in a test environment of 60°C × 90% RH × 750 hr, there is no foaming or peeling.

[0045] The pressure-sensitive adhesive layer according to this embodiment can be obtained by applying the pressure-sensitive adhesive composition of this embodiment to a base material such as a resin film or a release film, and then crosslinking the pressure-sensitive adhesive composition.

[0046] When the pressure-sensitive adhesive layer according to this embodiment is used for bonding between layers of an optical member, etc., in order to reduce the reflection of light at the interface between the pressure-sensitive adhesive layer and the optical member, it is desirable that the difference in refractive index be as small as possible. For this reason, it is preferable that the refractive index of the pressure-sensitive adhesive layer be 1.47 to 1.50.

[0047] The pressure-sensitive adhesive film according to this embodiment can be manufactured by forming the pressure-sensitive adhesive layer according to this embodiment on one surface of a base material such as a resin film or a release film. As the resin film or release film (separator) serving as the base material, a resin film such as a polyester film can be used. The release film may be subjected to a release treatment on the surface that is joined to the adhesive surface of the pressure-sensitive adhesive layer with a silicone-based or fluorine-based release agent, etc. The resin film serving as the base material can be subjected to an antifouling treatment with a silicone-based or fluorine-based release agent, a coating agent, silica fine particles, etc., and an antistatic treatment by applying or kneading an antistatic agent on the surface opposite to the side where the pressure-sensitive adhesive layer of the resin film is formed. The thickness of the pressure-sensitive adhesive layer can be, for example, a thickness of 1 μm to 25 μm.

[0048] By aligning the surfaces of the release films that have been release-treated on both sides of a single adhesive layer, a structure of "release film / adhesive layer / release film" can also be formed. In this case, by sequentially or simultaneously peeling off the release films on both sides to expose the adhesive surfaces, it becomes possible to bond with optical members such as optical films. Examples of optical films include polarizing films, retardation films, antireflection films, antiglare films, ultraviolet absorption films, infrared absorption films, optical compensation films, brightness enhancement films, and the like. Examples of devices to which optical members are applied include liquid crystal panels, organic EL panels, touch panels, in-cell type liquid crystal panels, and the like.

[0049] The pressure-sensitive adhesive film of the present embodiment is suitable as a pressure-sensitive adhesive film for a polarizing plate. In particular, it may be used for bonding a polarizing plate and an in-cell panel. Further, it can be made into an optical film with an adhesive layer in which the adhesive layer is laminated on at least one surface of the above optical film. By using the above pressure-sensitive adhesive film on one side of a polarizing plate, a polarizing plate with an adhesive layer can be provided. By using the above polarizing plate with an adhesive layer, a liquid crystal panel such as an in-cell type liquid crystal panel can be provided. Specific examples of the laminated structure of the optical film with an adhesive layer include "release film / adhesive layer / optical film", "release film / adhesive layer / optical film / adhesive layer / release film", "optical film / adhesive layer / optical film", "optical film / adhesive layer", "adhesive layer / optical film / adhesive layer", and the like. Specific examples of the laminated structure of the polarizing plate with an adhesive layer include "release film / adhesive layer / polarizing plate", "release film / adhesive layer / polarizing plate / adhesive layer / release film", "polarizing plate / adhesive layer", "adhesive layer / polarizing plate / adhesive layer", and the like. These laminated structures may be included as partial structures of liquid crystal panels and the like.

Examples

[0050] Hereinafter, the present invention will be specifically described with examples.

[0051] <Production of acrylic polymer> [Example 1] Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube to replace the air in the reaction apparatus with nitrogen gas. Thereafter, 70 parts by weight of n-butyl acrylate, 15 parts by weight of n-butyl methacrylate, 2.0 parts by weight of 8-hydroxyoctyl acrylate, 15 parts by weight of benzyl acrylate, and a solvent (ethyl acetate) were added to the reaction apparatus. Thereafter, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise over 2 hours and reacted at 65°C for 6 hours to obtain a solution of the acrylic polymer used in Example 1. [Examples 2 to 7 and Comparative Examples 1 to 3] Acrylic polymer solutions used in Examples 2 to 7 and Comparative Examples 1 to 3 were obtained in the same manner as in Example 1 above, except that the monomer composition was as described in (A) to (D) of Table 1. Although the measurement results are not particularly shown, the weight average molecular weight of the copolymer contained in the acrylic polymer solutions of Examples 1 to 7 and Comparative Examples 1 to 3 is in the range of 1 million to 3 million.

[0052] [Manufacture of Adhesive Film] [Example 1] To the acrylic polymer solution of Example 1 manufactured as described above, 10 parts by weight of cyclohexyltrimethylammonium bis(trifluoromethanesulfonyl)imide, 0.1 part by weight of a crosslinking agent (D-110N), and 0.05 part by weight of a silane coupling agent (X-12-967C) were added and stirred and mixed to obtain the adhesive composition of Example 1. This adhesive composition was applied onto a release film made of a silicone resin-coated polyethylene terephthalate (PET) film so that the thickness of the dried adhesive layer became 20 μm, and then dried at 90°C to remove the solvent. Thereafter, by aging in an atmosphere of 23°C and 50% RH for 7 days, an adhesive film of Example 1 having an adhesive layer obtained by crosslinking the adhesive composition on one side of the release film and having a structure of release film / adhesive layer / release film was obtained. [Examples 2 to 7 and Comparative Examples 1 to 3] The pressure-sensitive adhesive films of Examples 2 to 7 and Comparative Examples 1 to 3 were obtained in the same manner as the pressure-sensitive adhesive film of Example 1 described above, except that the composition of the additive was as described in (E) to (G) of Table 1, respectively.

[0053]

Table 1

[0054] In Table 1, the numerical values attached after the abbreviations of the respective components indicate parts by weight. These parts by weight are determined based on the total of (A), (B), and (D) being 100 parts by weight. Further, the compound names of the abbreviations of the respective components used in Table 1 are shown in Table 2. IOA is included in (B) for convenience. (C) was classified such that a monomer containing a hydroxyl group was designated as "(C)OH" and a monomer containing a carboxyl group was designated as "(C)COOH".

[0055]

Table 2

[0056] In Table 2, Coronate (registered trademark) L is a product name of Tosoh Corporation, D-110N is a product name of Mitsui Chemicals, Inc., and TETRAD (registered trademark)-X is a product name of Mitsubishi Gas Chemical Company, Inc. Further, TDI means tolylene diisocyanate, TMP means trimethylolpropane, and XDI means xylylene diisocyanate. Also, KBM-403, X-12-967C, X-41-1805, and KBM-503 are all product names of Shin-Etsu Chemical Co., Ltd.

[0057] <Test Method and Evaluation> From the pressure-sensitive adhesive films in Examples 1 to 7 and Comparative Examples 1 to 3, a release film (PET film coated with a silicone resin) was peeled off to expose one side of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film. Then, the pressure-sensitive adhesive film was bonded to one side of a polarizing plate (resin film) having a thickness of 80 μm via the pressure-sensitive adhesive layer to obtain a polarizing plate with a pressure-sensitive adhesive layer having a structure of release film / pressure-sensitive adhesive layer / polarizing plate.

[0058] <Method for Measuring Adhesion Strength> The release film of the polarizing plate with an adhesive layer obtained above was peeled off, and the polarizing plate with an adhesive layer was bonded to the surface of the non-alkali glass (Eagle XG (registered trademark) manufactured by Corning Inc.) washed with acetone through the adhesive layer using a pressure roller to prepare a test piece. Then, the test piece was autoclaved under the conditions of 50°C and 0.5 MPa for 20 minutes. After that, it was returned to the atmosphere of 23°C × 50% RH, and after 1 hour, the peel strength of the polarizing plate with an adhesive layer was measured by a tensile tester in accordance with JIS Z0237 "Test Method for Adhesive Tapes and Adhesive Sheets", and the peel strength when peeling at a speed of 0.3 m / min in the 180° direction was defined as the adhesion strength of the adhesive layer to the non-alkali glass.

[0059] <Method for Measuring Surface Resistivity> Regarding the polarizing plate with an adhesive layer obtained above, the surface resistivity (Ω / sq) of the adhesive layer was measured in an atmosphere of 23°C × 50% RH using a resistivity meter Hirester (registered trademark) UP-HT450 (manufactured by Mitsubishi Chemical Analytech) to obtain the initial surface resistivity. After subjecting the same polarizing plate with an adhesive layer to a durability test in a test environment of 85°C × 750 hr, the surface resistivity was measured in the same manner to obtain the surface resistivity after the durability test.

[0060] <Test Method for Durability> In the same manner as the measurement of the adhesion strength, the release film of the 10 cm square polarizing plate with an adhesive layer was peeled off and bonded to the surface of the non-alkali glass washed with acetone to prepare a test piece. Then, after subjecting the test piece to a durability test in a test environment of 85°C × 750 hr and a durability test in a test environment of 60°C × 90% RH × 750 hr, it was taken out into an atmosphere of 23°C × 50% RH, and after 1 hour, the state of the adhesive layer was visually observed to determine the durability. ○·· There is no foaming or peeling of the adhesive layer at all. △·· Foaming and peeling have occurred in a part of the adhesive layer. ×·· Foaming and peeling have occurred throughout the adhesive layer.

[0061] <Method for Evaluating Deposition State of Antistatic Agent> In the same manner as the measurement of adhesive strength, the release film of a polarizing plate with an adhesive layer of 10 cm square was peeled off and bonded to the surface washed with acetone of non-alkali glass to prepare a test piece. Then, for the test piece, after performing a durability test in a test environment of 85 °C × 750 hr and a durability test in a test environment of 60 °C × 90% RH × 750 hr, it was taken out in an atmosphere of 23 °C × 50% RH, and after 1 hour, the state of the adhesive layer was visually observed to judge the deposition state of the antistatic agent on the surface of the adhesive layer. ○ ·· There is no deposition of the antistatic agent on the surface of the adhesive layer. △ ·· Deposition of the antistatic agent has occurred on a part of the surface of the adhesive layer. × ·· Deposition of the antistatic agent has occurred on the entire surface of the adhesive layer.

[0062] Table 3 shows the evaluation results.

[0063]

Table 3

[0064] The adhesive films of Examples 1 to 7 have an adhesive strength to non-alkali glass of 1.0 to 6.0 N / 25 mm, and both the initial surface resistivity of the adhesive layer and the surface resistivity after the durability test in a test environment of 85 °C × 750 hr are 9.0×10 +10 Ω / □ or less, have durability without foaming and peeling after the durability test in a test environment of 85 °C × 750 hr and the durability test in a test environment of 60 °C × 90% RH × 750 hr, and there is no deposition of the antistatic agent on the surface of the adhesive layer. That is, the evaluation results for the adhesive films of Examples 1 to 7 demonstrate that the problems of the present invention can be solved.

[0065] In the pressure-sensitive adhesive film of Comparative Example 1, the alkyl (meth)acrylate monomer copolymerized with the acrylic polymer is not any of TBA, IBA, BMA, and MA, and a copolymerizable vinyl monomer containing an (D) aromatic group is not copolymerized. Therefore, although the adhesive strength of the pressure-sensitive adhesive layer before the durability test of the pressure-sensitive adhesive film of Comparative Example 1 was excessive, its durability was poor. Further, since the content ratio of the (E) antistatic agent in the pressure-sensitive adhesive film of Comparative Example 1 was increased, the surface resistivity of the pressure-sensitive adhesive layer was lowered, but the antistatic agent was entirely deposited on the surface of the pressure-sensitive adhesive layer after the durability test.

[0066] Although the pressure-sensitive adhesive film of Comparative Example 2 contains a (G) silane coupling agent, it does not contain at least one functional group selected from an epoxy group, a mercapto group, and an acid anhydride group. Therefore, the pressure-sensitive adhesive film of Comparative Example 2 was inferior in the durability of the pressure-sensitive adhesive layer, and the antistatic agent was partially deposited on the surface of the pressure-sensitive adhesive layer after the durability test.

[0067] In the pressure-sensitive adhesive film of Comparative Example 3, the alkyl (meth)acrylate monomer copolymerized with the acrylic polymer is not any of TBA, IBA, BMA, and MA, and a copolymerizable vinyl monomer containing an (D) aromatic group is not copolymerized. Therefore, even though the pressure-sensitive adhesive film of Comparative Example 3 does not contain a (G) silane coupling agent, the adhesive strength of the pressure-sensitive adhesive layer before the durability test was excessive, but its durability was poor. Further, since the content ratio of the (E) antistatic agent in the pressure-sensitive adhesive film of Comparative Example 3 was low, there was no deposition of the antistatic agent on the surface of the pressure-sensitive adhesive layer after the durability test, but the surface resistivity of the pressure-sensitive adhesive layer increased.

[0068] Thus, the pressure-sensitive adhesive films of Comparative Examples 1 to 3 could not solve the problems of the present invention.

[0069] According to the present invention, the surface resistivity of the pressure-sensitive adhesive layer is 9.0×10 +10Provided are an adhesive composition having extremely excellent antistatic performance of Ω / □ or less and not impairing durability, and an adhesive film using the same. Therefore, the adhesive composition according to the present invention and the adhesive film using the same are an adhesive composition and an adhesive film for use in bonding a polarizing plate and a liquid crystal panel, and have extremely excellent antistatic performance and durability, and thus have great industrial utility value.

Claims

1. An adhesive composition containing an acrylic polymer, an (E) antistatic agent, and an (F) crosslinking agent, wherein the acrylic polymer is, (A) n-butyl acrylate, at least one selected from the group consisting of (B) t-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, and methyl acrylate, at least one copolymerizable vinyl monomer containing a hydroxyl group and / or a carboxyl group, at least one copolymerizable vinyl monomer containing an aromatic group, and is an acrylic polymer having a weight average molecular weight of 1,000,000 to 3,000,000 obtained by copolymerizing them, the copolymerizable vinyl monomer containing a hydroxyl group and / or a carboxyl group is at least one or more selected from the group consisting of a copolymerizable monomer containing a hydroxyl group and a copolymerizable monomer containing a carboxyl group, and is contained in a proportion of 0.1 to 5 parts by weight with respect to a total of 100 parts by weight of the (A) n-butyl acrylate, at least one selected from the group consisting of the (B) t-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, and methyl acrylate, and at least one of the (D) copolymerizable vinyl monomers containing an aromatic group, the copolymerizable monomer containing a hydroxyl group is at least one or more selected from the group consisting of compounds such as 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxyethyl (meth)acrylamide, The copolymerizable monomer containing a carboxyl group is at least one selected from the group consisting of (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl maleic acid, carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyl tetrahydrophthalic acid, As the (E) antistatic agent, an ionic compound having a melting point of 25°C or higher, which consists of a fluorine group-containing anion and an ammonium cation, is contained in a proportion of 3 to 15 parts by weight with respect to 100 parts by weight of the acrylic polymer. With respect to 100 parts by weight of the acrylic polymer, 40 to 89 parts by weight of the (A) n-butyl acrylate and at least one selected from the group consisting of the (B) t-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, and methyl acrylate in a total amount of 5 to 40 parts by weight are contained, and the ratio (A) / (B) of (A) to (B) is 1.0 to 17.

8. As the (F) crosslinking agent, at least one crosslinking agent selected from the group consisting of a polyfunctional isocyanate compound having three or more functional groups and a polyfunctional epoxy compound having two or more functional groups is contained. The pressure-sensitive adhesive composition further contains a monomer type or oligomer type silane coupling agent containing at least one functional group selected from an epoxy group, a mercapto group, and an acid anhydride group. The pressure-sensitive adhesive composition is characterized by this.

2. A pressure-sensitive adhesive film characterized in that a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition according to claim 1 is laminated on a resin film.

3. A pressure-sensitive adhesive film having a structure of release film / pressure-sensitive adhesive layer / release film, wherein a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition according to claim 1 is formed on one side of the release film with a thickness of 1 μm to 25 μm.

4. A polarizing plate with a pressure-sensitive adhesive layer, characterized in that a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition according to claim 1 is laminated on one side of the polarizing plate, and has a structure of release film / pressure-sensitive adhesive layer / polarizing plate.

5. A liquid crystal panel, characterized in that a polarizing plate with an adhesive layer, in which an adhesive layer obtained by crosslinking the adhesive composition according to Claim 1 is laminated on one side of the polarizing plate, is used.

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