JP2022040324A - Adhesive agent composition and adhesive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive agent composition that has extremely excellent antistatic performance such that surface resistivity of an adhesive agent layer is 9.0×10⁺¹⁰ Ω/square or smaller, and does not deteriorate the durability, and an adhesive film used therefore.

SOLUTION: An adhesive agent composition is formed by containing an acrylic polymer obtained by copolymerizing (A) n-butyl acrylate; (B) at least one kind selected from t-butyl acrylate, isobutyl acrylate, n-butyl methacrylate and methyl acrylate, (C) a copolymerizable vinyl monomer containing a hydroxy group and/or a carboxyl group, and (D) a copolymerizable vinyl monomer containing an aromatic group, (E) an ammonia-based antistatic agent having a fluoro group-containing anion, (F) a crosslinking agent selected from trifunctional or higher functional isocyanate compounds, and bifunctional or higher functional epoxy compounds, (G) and a silane coupling agent containing a functional group selected from an epoxy group, a mercapto group, and an acid anhydride group.

SELECTED DRAWING: None

COPYRIGHT: (C)2022,JPO&INPIT

Description

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

Various adhesive films have been proposed for attaching 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 pressure-sensitive adhesive composition containing an acrylic polymer obtained by copolymerizing a monomer such as butyl acrylate as a main component and a acrylamide compound or the like.
Patent Document 2 contains an acrylic polymer obtained by copolymerizing a (meth) acrylate having an alkyl group having 4 to 8 carbon atoms as a main component, a carboxyl group-containing monomer, and a nitrogen-containing vinyl monomer. The pressure-sensitive adhesive composition is described.

Japanese Unexamined Patent Publication No. 2012-177022 Japanese Unexamined Patent Publication No. 2012-201734

By the way, in the pressure-sensitive adhesive layer for bonding a polarizing plate and a liquid crystal panel, when the liquid crystal panel becomes an in-cell panel incorporating a touch panel function, the surface resistivity of the pressure-sensitive adhesive layer is conventionally set. It is required to make the value lower than the surface resistivity of.
Therefore, the pressure-sensitive adhesive layer used for bonding the polarizing plate to the liquid crystal panel is required to have the surface resistivity of the pressure-sensitive adhesive layer of 9.0 × 10 ⁺¹⁰ Ω / □ or less. In, it was a very difficult situation to develop such a high degree of antistatic performance.
Further, even if such a high degree of antistatic performance can be exhibited, it is difficult to maintain the durability of the pressure-sensitive adhesive layer at the same time.

The present invention uses a pressure-sensitive adhesive composition having an extremely excellent antistatic performance having 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 composition thereof. An object of the present invention is to provide an adhesive film that has been used.

As a result of the diligent efforts of the present inventors to solve the difficult problem of achieving both high antistatic performance and durability at the same time, the alkyl constituting the acrylic polymer of the pressure-sensitive adhesive composition ( The number of carbon atoms of the alkyl group of the meta) acrylate is limited to a specific range to obtain an acrylic polymer composed of a copolymer obtained by copolymerizing two or more kinds of alkyl (meth) acrylates in a specific combination, and further, a specific combination. By using a pressure-sensitive adhesive composition containing an antistatic agent, it has become possible to solve this problem.

The present inventors have made the acrylic polymer and 100 parts by weight of the acrylic polymer contain 2.5 to 15 parts by weight of an ammonium-based antistatic agent having a fluoro group-containing anion. It has been determined that a pressure-sensitive adhesive composition having extremely excellent antistatic performance as compared with a conventional pressure-sensitive adhesive composition, and having excellent durability without precipitating an antistatic agent and not deteriorating over time can be obtained. I found it and completed the present invention.

The pressure-sensitive adhesive composition according to the present invention has an extremely excellent antistatic performance of 9.0 × 10 ⁺¹⁰ Ω / □ or less on the surface resistivity of the pressure-sensitive adhesive layer with respect to 100 parts by weight of the acrylic polymer. An ammonium-based antistatic agent having a fluorogroup-containing anion is contained in a proportion of 2.5 to 15 parts by weight. As described above, 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 in a high-temperature and high-humidity environment, an ammonium-based antistatic agent having a fluorogroup-containing anion contained in a large amount in the pressure-sensitive adhesive layer precipitates on the surface of the pressure-sensitive adhesive layer. In order to form a pressure-sensitive adhesive layer that can maintain durability without using it, select a monomer whose acrylic polymer contained in the pressure-sensitive adhesive composition is mainly n-butyl acrylate (BA) and has good copolymerizability with BA. The technical idea is to be copolymerized.

Further, in order to solve the above-mentioned problems, the present invention is a pressure-sensitive adhesive composition containing an acrylic polymer, an antioxidant, and a cross-linking agent, wherein the acrylic polymer is (A) n-butyl. A copolymerizable vinyl monomer containing (C) a hydroxyl group and / or a carboxyl group, and at least one selected from the group consisting of acrylate, (B) t-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, and methyl acrylate. (D) An acrylic polymer having a weight average molecular weight of 1 million to 3 million obtained by copolymerizing at least one of (D) and at least one of a copolymerizable vinyl monomer containing an aromatic group. As the (E) antistatic agent, an ammonium-based antistatic agent having a fluorogroup-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) cross-linking agent, at least one cross-linking agent selected from the group consisting of a trifunctional or higher functional isocyanate compound and a bifunctional or higher functional epoxy compound is contained, and the pressure-sensitive adhesive composition further comprises. (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 is contained, and the pressure-sensitive adhesive composition is crosslinked. The surface resistance of the coated pressure-sensitive adhesive layer is 9.0 × 10 ^{+ 10} Ω / □ or less, and the pressure-sensitive adhesive layer is subjected to a durability test in a test environment of 85 ° C. × 750 hr, or after being subjected to a durability test at 60 ° C. Provided is a pressure-sensitive adhesive composition characterized in that the antioxidant is not deposited on the surface of the pressure-sensitive adhesive layer after being subjected to a durability test in a test environment of × 90% RH × 750 hr.

The antistatic agent is an ionic compound composed of a fluorogroup-containing anion and an ammonium cation having a melting point of 25 ° C. or higher, and the fluorogroup-containing anion is pentafluorobenzene sulfonate, hexafluorophosphate, or bis (trifluo). It is preferably one selected from the group consisting of quaternary sulfonyl) imide, bis (fluorosulfonyl) imide, and triflate.

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

When a polarizing plate having a total thickness of 80 μm is attached to non-alkali glass via a 20 μm thick pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition, the adhesive force of the pressure-sensitive adhesive layer against the non-alkali glass is increased. A 10 cm square plate plate having a total thickness of 80 μm, which is 1.0 to 6.0 N / 25 mm and has a thickness of 20 μm cross-linked with the pressure-sensitive adhesive composition, is bonded to non-alkali glass. After the test piece is subjected to a durability test in a test environment of 85 ° C. × 750 hr, or after a durability test in a test environment of 60 ° C. × 90% RH × 750 hr, foaming and peeling are performed. It is preferable that there is no such thing.

(C) The copolymerizable vinyl monomer containing a hydroxyl group and / or a carboxyl group is at least one selected from the group consisting of a copolymerizable monomer containing a hydroxyl group and a copolymerizable monomer containing a carboxyl group. It is a seed or more, and is contained in a ratio of 0.1 to 5 parts by weight with respect to a total of 100 parts by weight of the above (A), the above (B) and the above (D), and contains the hydroxyl group. The polymerizable monomers are 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, The copolymerizable monomer which is at least one selected from the compound group consisting of N-hydroxymethyl (meth) acrylamide and N-hydroxyethyl (meth) acrylamide and contains the carboxyl group is (meth). Acrylate, Carboxyloxy (meth) Acrylate, Carboxypentyl (Meta) Acrylate, 2- (Meta) Acryloyloxyethyl Hexahydrophthalic Acid, 2- (Meta) Acryloyloxypropyl Hexahydrophthalic Acid, 2- (Meta) Acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid, carboxypolycaprolactone mono (meth) acrylate, 2- (meth) acryloyloxyethyl tetrahydro It is preferably at least one selected from the group of compounds consisting of phthalic acid.

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 both 9.0 × 10 ^{+ 10} Ω / □ or less. Is preferable.

The present invention also provides a pressure-sensitive adhesive film, wherein the pressure-sensitive adhesive layer obtained by cross-linking the above-mentioned pressure-sensitive adhesive composition is laminated on one side of the resin film.

The present invention also provides a pressure-sensitive adhesive film for a polarizing plate using the above-mentioned pressure-sensitive adhesive film.

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

Further, according to the present invention, the release film / pressure-sensitive adhesive layer / release film in which the pressure-sensitive adhesive layer obtained by cross-linking the above-mentioned pressure-sensitive adhesive composition on one side of the release film is formed with a thickness of 1 μm to 25 μm. Provided is an adhesive film characterized by being configured.

Further, in the present invention, the pressure-sensitive adhesive layer obtained by cross-linking the above-mentioned pressure-sensitive adhesive composition is laminated on at least one surface of the optical film to form a release film / pressure-sensitive adhesive layer / optical film. Provided is an optical film with a characteristic pressure-sensitive adhesive layer.

Further, the present invention is characterized in that a pressure-sensitive adhesive layer obtained by cross-linking the above-mentioned pressure-sensitive adhesive composition is laminated on one side of a polarizing plate to form a release film / pressure-sensitive adhesive layer / polarizing plate. A polarizing plate with an adhesive layer is provided.

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

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

According to the present invention, a pressure-sensitive adhesive composition having an extremely excellent antistatic performance having 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 composition thereof. It is possible to provide an adhesive film using the above.

Hereinafter, the present invention will be described based on a preferred embodiment.

The pressure-sensitive adhesive composition of the present embodiment is a pressure-sensitive adhesive composition containing an acrylic polymer, an antistatic agent, and a cross-linking agent, and the acrylic polymer is (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, and (C) at least one copolymerizable vinyl monomer containing a hydroxyl group and / or a carboxyl group. (D) An acrylic polymer having a weight average molecular weight of 1 to 3 million, which is a copolymer obtained by copolymerizing at least one of a copolymerizable vinyl monomer containing an aromatic group, described in (E) above. As the antistatic agent, an ammonium-based antistatic agent having a fluorogroup-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, and the (F) cross-linking is carried out. As the agent, at least one cross-linking agent selected from the group consisting of a trifunctional or higher functional isocyanate compound and a bifunctional or higher functional epoxy compound is contained, and the pressure-sensitive adhesive composition further comprises a (G) epoxy group. , A pressure-sensitive adhesive layer containing a monomer-type or oligomer-type silane coupling agent containing at least one functional group selected from a mercapto group and an acid anhydride group, and cross-linking the pressure-sensitive adhesive composition. The surface resistance of the polymer is 9.0 × 10 ^{+ 10} Ω / □ or less, and the pressure-sensitive adhesive layer is subjected to a durability test in a test environment of 85 ° C. × 750 hr, or 60 ° C. × 90% RH ×. It is characterized in that the antioxidant is not deposited on the surface of the pressure-sensitive adhesive layer after being subjected to a durability test in a test environment of 750 hr.

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

The acrylic polymer of the present embodiment is mainly composed of (A) n-butyl acrylate, and for example, contains (A) n-butyl acrylate in a ratio of 40 to 89 parts by weight with respect to 100 parts by weight of the acrylic polymer. It is preferable to do. Further, the acrylic polymer is selected from the group consisting of (B) t-butyl acrylate, isobutyl acrylate, n-butyl methacrylate and methyl acrylate as an alkyl (meth) acrylate monomer other than (A) n-butyl acrylate. It is preferable that the total of one or more kinds is contained in a ratio of 5 to 40 parts by weight. Moreover, it is preferable that the ratio (A) / (B) of (A) and (B) is 1.0 to 17.8 as a weight ratio.

(C) As the copolymerizable vinyl monomer containing a hydroxyl group and / or a carboxyl group, a copolymerizable monomer containing a hydroxyl group (hydroxyl group-containing monomer) and a copolymerizable monomer containing a carboxyl group (carboxyl group). At least one selected from the group consisting of (containing monomers) can be mentioned. That is, only one of the hydroxyl group-containing monomer and the carboxyl group-containing monomer may be selected and copolymerized, or both the hydroxyl group-containing monomer and the carboxyl group-containing monomer may be copolymerized. (C) The ratio of the copolymerizable vinyl monomer containing a hydroxyl group and / or a carboxyl group is 0.1 to 5 parts by weight with respect to 100 parts by weight in total of (A), (B) and (D). It is preferably a ratio. In addition, (A), (B) and (D) are all vinyl monomers which do not contain a hydroxyl group and a carboxyl group.

Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxyethyl (meth) acrylate. ) Acrylate, and at least one of hydroxyl group-containing (meth) acrylamides such as N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide can be mentioned.
Further, the hydroxyl group-containing monomer contained in the pressure-sensitive adhesive composition according to the present embodiment is said to affect the corrosiveness of the obtained pressure-sensitive adhesive layer to a corrosive adherend such as the ITO surface of a transparent conductive film. It can be used as a copolymerizable monomer for reducing the content of the carboxyl group-containing monomer. Therefore, the hydroxyl group-containing monomer can be useful for improving the adhesive strength of the pressure-sensitive adhesive layer and reducing the corrosiveness. The ratio of the hydroxyl group-containing monomer contained in the pressure-sensitive adhesive composition of the present embodiment is 0.1 to 5.0 parts by weight with respect to 100 parts by weight in total of (A), (B) and (D). The ratio is preferably 0.1 to 4.4 parts by weight, more preferably 0.1 to 3.8 parts by weight, and particularly preferably 0.1 to 3.8 parts by weight.

Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, and 2- (meth) acryloy. Loxypropyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid, carboxypolycaprolactone mono (meth) At least one of acrylate, 2- (meth) acryloyloxyethyl tetrahydrophthalic acid and the like can be mentioned.
Further, the carboxyl group-containing monomer contained in the pressure-sensitive adhesive composition according to the present embodiment can impart a necessary cohesive force to the obtained pressure-sensitive adhesive layer. The ratio of the carboxyl group-containing monomer in the pressure-sensitive adhesive composition according to the present embodiment is 0 to 5.0 parts by weight with respect to 100 parts by weight in total of (A), (B) and (D). preferable. When the hydroxyl group-containing monomer is copolymerized with the acrylic polymer, it is permissible not to copolymerize the carboxyl group-containing monomer. Further, when the carboxyl group-containing monomer is copolymerized, the ratio is more preferably 0.01 to 5.0 parts by weight, and particularly preferably 0.01 to 3.3 parts by weight. Most preferably, the ratio is 0.01 to 2.8 parts by weight.

Examples of the copolymerizable vinyl monomer containing the (D) aromatic group include benzyl (meth) acrylate, naphthyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxybutyl (meth) acrylate, and 2- (1-). Naftyloxy) 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 and the like. (D) As the copolymerizable vinyl monomer containing an aromatic group, when a (meth) acrylate monomer containing an aromatic group is contained, an alkyl (meth) acrylate composed of a combination of (A) and (B) is contained. It is preferable because it has excellent copolymerizability with a monomer.

In order to obtain a pressure-sensitive adhesive layer having a high refractive index, it is preferable to add at least one (meth) acrylate monomer containing an aromatic group to the pressure-sensitive adhesive composition according to the present embodiment. By copolymerizing the (meth) acrylate monomer containing these aromatic groups with an acrylic polymer, the refractive index of the obtained pressure-sensitive adhesive layer can be increased and adjusted, and the difference in refractive index between the optical members can be reduced. Therefore, the total light transmittance can be improved by reducing the total reflection. In the pressure-sensitive adhesive composition according to the present embodiment, the (meth) acrylate monomer containing an aromatic group is preferably contained in a proportion of 5 to 30 parts by weight with respect to 100 parts by weight of the acrylic polymer, 6 by weight. It is more preferably contained in a proportion of up to 28 parts by weight, and particularly preferably contained in a proportion of 6 to 24 parts by weight.

The method for producing the acrylic polymer contained in the pressure-sensitive adhesive composition according to the present embodiment is not particularly limited, and known polymerization methods such as a solution polymerization method and an emulsion polymerization method can be used as appropriate. The weight average molecular weight of the acrylic polymer copolymer is preferably 1 to 3 million.

The pressure-sensitive adhesive composition according to the present embodiment contains (E) an antistatic agent in order to obtain antistatic performance. (E) As the antistatic agent, it is preferable to contain an ammonium-based antistatic agent having a fluoro group-containing anion at a ratio of 2.5 to 15 parts by weight with respect to 100 parts by weight of the acrylic polymer. It is more preferably contained in a proportion of 3 to 15 parts by weight, and particularly preferably contained in a proportion of 4 to 15 parts by weight. This antistatic agent is an ionic compound composed of a fluorogroup-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, the ionic compound is more preferably an ionic compound having a melting point of 25 ° C. to 80 ° C., which is solid at a temperature of 25 ° C.

(E) Examples of the fluoro group-containing anion contained in the antistatic agent include an inorganic or organic fluoro group-containing anion. Here, the fluoro group means a fluorine atom bonded to another atom constituting an anion. Examples of the inorganic fluorogroup-containing anion include PF _6- ^, AsF _6- ^, SbF _6- ^, BF _4- ^, AlF _4- ^, (FSO ₂ ) ₂ N- ^, FSO _3- , ^and the like. Examples of the organic fluoro group-containing anion include a fluoro group-containing sulfonate anion (RSO _3- ⁾ , a fluoro group-containing carboxylate anion ( ^RCOO- ), a fluoro group ^- containing alkoxide or phenoxide anion (RO-), and a fluoro group-containing anion. Organic imide anion (R ₂ N-), fluoro group ^- containing methide (R ₃ C- ⁾ anion, fluoro group-containing organic borate (R ₄ B- ⁾ anion, etc., containing at least one of R and containing a fluoro group. Anions having an organic group can be mentioned. 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 2 or more Rs, it may have a bond between the 2 or more Rs to form a ring. Among them, one selected from the group consisting of pentafluorobenzene sulfonate, hexafluorophosphate, bis (trifluoromethanesulfonyl) imide, bis (fluorosulfonyl) imide, and triflate is preferable.

(E) Examples of the ammonium cation contained in the antistatic agent include an organic ammonium cation having 1 to 4 organic groups, and a quaternary ammonium cation ( _R4 N ⁺ ) is particularly 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 2 or more Rs, it may have a bond between the 2 or more Rs to form a ring.

The pressure-sensitive adhesive composition according to the present embodiment further contains (F) at least one cross-linking agent selected from the group consisting of a trifunctional or higher functional isocyanate compound and a bifunctional or higher functional epoxy compound as the (F) cross-linking agent. .. Examples of the ratio of the (F) cross-linking agent include 0.01 to 5 parts by weight with respect to 100 parts by weight of the acrylic polymer.

Examples of the trifunctional or higher functional isocyanate compound include bullet-modified and isocyanurate-modified compounds of diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, and xylylene diisocyanate, trimethylolpropane, and glycerin. Examples thereof include an adduct with a polyol having a valence of 3 or more.
Examples of the bifunctional or higher functional epoxy compound include glycol diglycidyl ether, bisphenol diglycidyl ether, triol triglycidyl ether, dicarboxylic acid diglycidyl ester, diglycidyl substituted amines, and tetraglycidyl substituted diamines. Can be mentioned.

The pressure-sensitive adhesive composition according to the present embodiment further contains (G) a silane coupling agent. The (G) silane coupling agent has 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 or the like. Some compounds are mentioned. (G) The silane coupling agent contains at least one functional group selected from an epoxy group, a mercapto group and an acid anhydride group. As the (G) silane coupling agent, at least one or more of one or both of the monomer type and the oligomer type can be used. 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.

Examples of the silane coupling agent having an epoxy group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropyl. Triethoxysilane, 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- Epoxide hexyltriethoxysilane and the like can be mentioned. Examples of the silane coupling agent having a mercapto group include 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, and 3-mercaptopropyltriethoxysilane. Examples of the silane coupling agent having an acid anhydride group include 3-trimethoxysilylpropyl succinic acid anhydride and 3-triethoxysilylpropyl succinic acid anhydride. Further, an oligomerized alkoxy oligomer (silicone alkoxy oligomer) or the like can also be used as a silane coupling agent.

The pressure-sensitive adhesive composition of the present embodiment has, as any component, an antioxidant, a surfactant, a curing accelerator, a plasticizer, a filler, a cross-linking catalyst, a cross-linking retarder, a curing retarder, a processing aid, and an antiaging agent. Known additives such as agents can be appropriately blended. These may be used alone or in combination of two or more.

The surface resistivity of the pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition of the present embodiment is preferably 9.0 × 10 ⁺¹⁰ Ω / □ or less, and is 5.0 × 10 ⁺¹⁰ Ω / □ or less. Is more preferable, and 2.0 × 10 ⁺¹⁰ Ω / □ or less is particularly preferable. The initial surface resistivity and the surface resistivity after the durability test of this pressure-sensitive adhesive layer are preferably 9.0 × 10 ⁺¹⁰ Ω / □ or less, and 5.0 × 10 ⁺¹⁰ Ω / It is more preferably □ or less, and particularly preferably 2.0 × 10 ⁺¹⁰ Ω / □ or less. Here, the initial surface resistivity is the surface resistivity before the pressure-sensitive adhesive layer is subjected to the durability test. The surface resistivity after the durability test is the surface resistivity after the pressure-sensitive adhesive layer is subjected to the durability test in a test environment of 85 ° C. × 750 hr. Here, the test environment of 85 ° C. × 750 hr may be a dry condition.

The pressure-sensitive adhesive layer crosslinked with the pressure-sensitive adhesive composition of the present embodiment was subjected 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. Later, the (E) antistatic agent is not deposited on the surface of the pressure-sensitive adhesive layer. Here, the test environment of 85 ° C. × 750 hr may be a dry condition.
The antistatic performance of the (E) antistatic agent in the pressure-sensitive adhesive composition of the present embodiment is such that two or more samples of the pressure-sensitive adhesive layer obtained by cross-linking the same pressure-sensitive adhesive composition are prepared, and one sample is produced at 85 ° C. × 750 hr. After being subjected to the durability test under the test environment of (E), the antistatic agent did not precipitate, and another sample was subjected to the durability test under the test environment of 60 ° C. × 90% RH × 750 hr ( E) The antistatic agent may not be deposited.

The pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition of the present embodiment is formed by bonding a polarizing plate having a total thickness of 80 μm to non-alkali glass via a pressure-sensitive adhesive layer having a thickness of 20 μm. The adhesive strength to non-alkali glass is preferably 1.0 to 6.0 N / 25 mm.
Further, a test piece obtained by laminating a 10 cm square polarizing plate having a total thickness of 80 μm on non-alkali glass via an adhesive layer having a thickness of 20 μm was subjected to a durability test in a test environment of 85 ° C. × 750 hr. And 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.
For the performance of the pressure-sensitive adhesive composition of the present embodiment without foaming and peeling, two or more test pieces prepared using the same pressure-sensitive adhesive composition are prepared, and one test piece is prepared in a test environment of 85 ° C. × 750 hr. No foaming or peeling after being subjected to the durability test in the above, and no foaming or peeling after another test piece was subjected to the durability test under the test environment of 60 ° C. × 90% RH × 750 hr. There may be.

The pressure-sensitive adhesive layer according to the present embodiment can be obtained by applying the pressure-sensitive adhesive composition of the present embodiment to a substrate such as a resin film or a release film, and then cross-linking the pressure-sensitive adhesive composition.

When the pressure-sensitive adhesive layer according to the present embodiment is used for bonding layers of optical members, the difference in refractive index should be as small as possible in order to reduce the reflection of light rays at the interface between the pressure-sensitive adhesive layer and the optical member. desirable. Therefore, the refractive index of the pressure-sensitive adhesive layer is preferably 1.47 to 1.50.

The pressure-sensitive adhesive film according to the present embodiment can be produced by forming the pressure-sensitive adhesive layer according to the present embodiment on one side of a base material such as a resin film or a release film. As the resin film or release film (separator) as the base material, a resin film such as a polyester film can be used. The release film may be subjected to a mold release treatment with a silicone-based or fluorine-based mold release agent or the like on the surface of the pressure-sensitive adhesive layer on the side to be combined with the adhesive surface. The resin film used as the base material has a silicone-based or fluorine-based mold release agent or coating agent, an antifouling treatment with silica fine particles, and an antistatic agent on the opposite side of the resin film from the side on which the pressure-sensitive adhesive layer is formed. Antistatic treatment can be applied by coating or kneading. Examples of the thickness of the pressure-sensitive adhesive layer include a thickness of 1 μm to 25 μm.

It is also possible to form a "release film / adhesive layer / release film" by aligning the surfaces of the release film that have been subjected to the release treatment on both sides of one pressure-sensitive adhesive layer. In this case, by peeling off the release films on both sides sequentially or simultaneously to expose the adhesive surface, it becomes possible to bond the release films to an optical member such as an optical film. Examples of the optical film include a polarizing film, a retardation film, an antireflection film, an antiglare film, an ultraviolet absorbing film, an infrared absorbing film, an optical compensation film, and a brightness improving film. Examples of the device to which the optical member is applied include a liquid crystal panel, an organic EL panel, a touch panel, an in-cell type liquid crystal panel and the like.

The pressure-sensitive adhesive film of this embodiment is suitable as a pressure-sensitive adhesive film for a polarizing plate. In particular, it may be used for bonding the polarizing plate and the in-cell panel. Further, an optical film with an adhesive layer obtained by laminating the adhesive layer on at least one surface of the optical film can be obtained. By using the above-mentioned pressure-sensitive adhesive film on one side of the polarizing plate, a polarizing plate with a pressure-sensitive adhesive layer can be provided. A liquid crystal panel such as an in-cell type liquid crystal panel can be provided by using the above-mentioned polarizing plate with an adhesive layer.
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", and "optical". Examples thereof include "film / adhesive layer / optical film", "optical film / adhesive layer", and "adhesive layer / optical film / adhesive layer". Specific examples of the laminated structure of the polarizing plate with the pressure-sensitive adhesive layer include "release film / pressure-sensitive adhesive layer / polarizing plate", "release film / pressure-sensitive adhesive layer / polarizing plate / pressure-sensitive adhesive layer / release film", and "polarized film". Examples thereof include "plate / adhesive layer" and "adhesive layer / polarizing plate / adhesive layer". These laminated configurations may be included as a partial structure of a liquid crystal panel or the like.

Hereinafter, the present invention will be specifically described with reference to Examples.

<Manufacturing of acrylic polymer>
[Example 1]
Nitrogen gas was introduced into a reactor equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen introduction tube, and the air in the reactor was replaced with nitrogen gas. Then, a solvent (ethyl acetate) was added to the reaction apparatus together with 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, and 15 parts by weight of benzyl acrylate. Then, 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]
Acrylics used in Examples 2 to 7 and Comparative Examples 1 to 3 in the same manner as in Example 1 above, except that the composition of each of the monomers is as described in Table 1 (A) to (D). A polymer solution was obtained.
Although the measurement results are not particularly shown, the weight average molecular weight of the copolymers contained in the acrylic polymer solutions of Examples 1 to 7 and Comparative Examples 1 to 3 is in the range of 1 to 3 million.

<Manufacturing of adhesive film>
[Example 1]
10 parts by weight of cyclohexyltrimethylammonium bis (trifluoromethanesulfonyl) imide, 0.1 part by weight of a cross-linking agent (D-110N), and a silane cup with respect to the acrylic polymer solution of Example 1 produced as described above. The ring agent (X-12-967C) was added at a ratio of 0.05 parts by weight and stirred and mixed to obtain the pressure-sensitive adhesive composition of Example 1.
This pressure-sensitive adhesive composition is applied onto a release film made of a polyethylene terephthalate (PET) film coated with a silicone resin so that the thickness of the pressure-sensitive adhesive layer after drying is 20 μm, and then dried at 90 ° C. This removed the solvent. Then, by aging in an atmosphere of 23 ° C. and 50% RH for 7 days, a pressure-sensitive adhesive layer cross-linked with the pressure-sensitive adhesive composition is provided on one side of the release film, and the release film / pressure-sensitive adhesive layer / An adhesive film of Example 1, which is a structure of a release film, was obtained.
[Examples 2 to 7 and Comparative Examples 1 to 3]
Examples 2 to 7 and Comparative Examples 1 to 3 are the same as those of the above-mentioned adhesive film of Example 1 except that the composition of the additive is as described in (E) to (G) of Table 1, respectively. Adhesive film was obtained.

In Table 1, the numerical value added after the abbreviation of each component indicates the part by weight. This part by weight is obtained by taking the total of (A), (B) and (D) as 100 parts by weight. The compound names of the abbreviations of each component used in Table 1 are shown in Table 2. The IOA is included in (B) for convenience. In (C), the monomer containing a hydroxyl group was classified as "(C) OH", and the monomer containing a carboxyl group was classified as "(C) COOH".

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

<Test method and evaluation>
The release film (PET film coated with a silicone resin) was peeled off from the pressure-sensitive adhesive films of Examples 1 to 7 and Comparative Examples 1 to 3 to expose one side of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film. After that, the pressure-sensitive adhesive film is attached to one side of a polarizing plate (resin film) having a thickness of 80 μm via the pressure-sensitive adhesive layer to form a release film / pressure-sensitive adhesive layer / polarizing plate. A layered polarizing plate was obtained.

<Measurement method of adhesive strength>
The release film of the polarizing plate with the pressure-sensitive adhesive layer obtained above was peeled off, and the surface of non-alkali glass (Eagle XG (registered trademark) manufactured by Corning Co., Ltd.) washed with acetone was passed through the pressure-sensitive adhesive layer. A polarizing plate with an adhesive layer was bonded with a pressure-bonding roll to prepare a test piece. Then, the test piece was autoclaved at 50 ° C. for 0.5 MPa × 20 minutes. After that, the temperature is returned to the atmosphere of 23 ° C. × 50% RH, and the peel strength of the polarizing plate with the adhesive layer after 1 hour is measured by a tensile tester in accordance with JIS Z0237 “Adhesive Tape / Adhesive Sheet Test Method”. The peel strength when peeled at a rate of 0.3 m / min in the 180 ° direction was defined as the adhesive strength of the pressure-sensitive adhesive layer against the non-alkali glass.

<Measurement method of surface resistivity>
Regarding the polarizing plate with the pressure-sensitive adhesive layer obtained above, the surface of the pressure-sensitive adhesive layer was used in an atmosphere of 23 ° C. × 50% RH using a resistivity meter Hiresta (registered trademark) UP-HT450 (manufactured by Mitsubishi Chemical Analytec). The resistivity (Ω / □) was measured to determine the initial surface resistivity. The same polarizing plate with an adhesive layer was subjected to a durability test in a test environment of 85 ° C. × 750 hr, and then the surface resistivity was measured in the same manner to determine the surface resistivity after the durability test.

<Durability test method>
A test piece was prepared by peeling off the release film of a 10 cm square polarizing plate with an adhesive layer and pasting it on a surface of non-alkali glass washed with acetone by the same method as for measuring the adhesive strength. Then, the test piece was subjected to a durability test under a test environment of 85 ° C. × 750 hr and a durability test under a test environment of 60 ° C. × 90% RH × 750 hr, and then under a 23 ° C. × 50% RH atmosphere. After 1 hour, the state of the pressure-sensitive adhesive layer was visually observed to determine the durability.
○ ・ ・ There is no foaming or peeling of the adhesive layer.
△ ・ ・ Foaming and peeling occur in a part of the adhesive layer.
× ・ ・ Foaming and peeling occur on the entire adhesive layer.

<Evaluation method of precipitation state of antistatic agent>
A test piece was prepared by peeling off the release film of a 10 cm square polarizing plate with an adhesive layer and pasting it on a surface of non-alkali glass washed with acetone by the same method as for measuring the adhesive strength. Then, the test piece was subjected to a durability test under a test environment of 85 ° C. × 750 hr and a durability test under a test environment of 60 ° C. × 90% RH × 750 hr, and then under a 23 ° C. × 50% RH atmosphere. After 1 hour, the state of the pressure-sensitive adhesive layer was visually observed to determine the state of precipitation of the antistatic agent on the surface of the pressure-sensitive adhesive layer.
○ ・ ・ There is no precipitation of antistatic agent on the surface of the adhesive layer.
Δ ・ ・ Antistatic agent is deposited on a part of the surface of the pressure-sensitive adhesive layer.
× ・ ・ Antistatic agent is deposited on the entire surface of the pressure-sensitive adhesive layer.

Table 3 shows the evaluation results.

The adhesive films of Examples 1 to 7 have an adhesive force with respect to non-alkali glass of 1.0 to 6.0 N / 25 mm, and have an initial surface resistivity of the adhesive layer and a test environment of 85 ° C. × 750 hr. The surface resistivity after the durability test in the above is 9.0 × 10 ^{+ 10} Ω / □ or less, and the durability test under the test environment of 85 ° C. × 750 hr and the test of 60 ° C. × 90% RH × 750 hr. After the durability test in the environment, there was no foaming or peeling, the durability was high, and no antistatic agent was deposited on the surface of the pressure-sensitive adhesive layer. That is, the evaluation results of the pressure-sensitive adhesive films of Examples 1 to 7 demonstrate that the problem of the present invention could be solved.

In the pressure-sensitive adhesive film of Comparative Example 1, the alkyl (meth) acrylate monomer copolymerized with the acrylic polymer was not TBA, IBA, BMA, or MA, and was copolymerizable containing (D) an aromatic group. The vinyl monomer is not copolymerized. Therefore, in the adhesive film of Comparative Example 1, the adhesive strength of the adhesive layer before the durability test was excessive, but the durability was inferior. Further, in the pressure-sensitive adhesive film of Comparative Example 1, since the content ratio of the (E) antistatic agent was high, the surface resistivity of the pressure-sensitive adhesive layer was low, but after the durability test, the antistatic agent was used as the pressure-sensitive adhesive. Precipitated entirely on the surface of the layer.

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.

In the pressure-sensitive adhesive film of Comparative Example 3, the alkyl (meth) acrylate monomer copolymerized with the acrylic polymer was not TBA, IBA, BMA, or MA, and was copolymerizable containing (D) an aromatic group. The vinyl monomer is not copolymerized. Therefore, even if the adhesive film of Comparative Example 3 does not contain the (G) silane coupling agent, the adhesive strength of the adhesive layer before the durability test is excessive, but the durability is inferior. Further, since the pressure-sensitive adhesive film of Comparative Example 3 contained a small amount of the (E) antistatic agent, the antistatic agent did not precipitate on the surface of the pressure-sensitive adhesive layer after the durability test, but the pressure-sensitive adhesive layer was not deposited. The surface resistivity has increased.

As described above, the adhesive films of Comparative Examples 1 to 3 could not solve the problem of the present invention.

According to the present invention, a pressure-sensitive adhesive composition having an extremely excellent antistatic performance having 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 composition thereof. It is possible to provide an adhesive film using the above. Therefore, the pressure-sensitive adhesive composition according to the present invention and the pressure-sensitive adhesive film using the pressure-sensitive adhesive composition are extremely excellent as the pressure-sensitive adhesive composition for bonding the polarizing plate and the liquid crystal panel and the pressure-sensitive adhesive film using the pressure-sensitive adhesive composition. Since it has antistatic performance and durability, it has great industrial utility value.

Claims (5)

A pressure-sensitive adhesive composition containing an acrylic polymer, an antistatic agent, and a cross-linking agent.
The acrylic polymer is
(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, and
(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
It is an acrylic polymer having a weight average molecular weight of 1 million to 3 million.
(C) The copolymerizable vinyl monomer containing a hydroxyl group and / or a carboxyl group is at least one selected from the group consisting of a copolymerizable monomer containing a hydroxyl group and a copolymerizable monomer containing a carboxyl group. It is a seed or more, and is contained in a ratio of 0.1 to 5 parts by weight with respect to a total of 100 parts by weight of the above (A), the above (B) and the above (D).
The copolymerizable monomer containing a hydroxyl group is 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-. At least one selected from the compound group consisting of hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide.
The carboxyl group-containing copolymerizable monomers include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, and 2-(. Meta) acryloyloxypropyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid, carboxypolycaprolactone At least one selected from the compound group consisting of mono (meth) acrylate and 2- (meth) acryloyloxyethyl tetrahydrophthalic acid.
As the (E) antistatic agent, an ammonium-based antistatic agent having a fluorogroup-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) cross-linking agent, at least one cross-linking agent selected from the group consisting of a trifunctional or higher functional isocyanate compound and a bifunctional or higher functional epoxy compound 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 (G) epoxy group, mercapto group, and acid anhydride group. A pressure-sensitive adhesive composition characterized by becoming. A pressure-sensitive adhesive film obtained by laminating a pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition according to claim 1 on a resin film. A release film / pressure-sensitive adhesive layer / release film having a pressure-sensitive adhesive layer having the pressure-sensitive adhesive composition according to claim 1 crosslinked on one side of the release film having a thickness of 1 μm to 25 μm. An adhesive film characterized by being present. A pressure-sensitive adhesive characterized by having a release film / pressure-sensitive adhesive layer / polarizing plate formed by laminating a pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition according to claim 1 on one surface of the polarizing plate. Polarizer with layer. A liquid crystal panel characterized in that a polarizing plate with a pressure-sensitive adhesive layer, in which a pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition according to claim 1 is laminated on one surface of the polarizing plate.