JP6843041B2 - Adhesive composition and adhesive film - Google Patents

Description

The present invention relates to an adhesive composition and an adhesive film used for bonding optical members.
More specifically, a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having extremely excellent antistatic performance, in which the surface resistivity of the pressure-sensitive adhesive layer is 1.0 × 10 ^{+ 9 Ω / □ or less, which cannot be achieved by the prior art.} , And the adhesive film using it.

Various adhesive films have been proposed for attaching optical members such as polarizing plates and retardation plates to adherends such as liquid crystal cells via an adhesive layer (for example, Patent Documents 1 and 2). reference).
Patent Document 1 describes (A) an acrylic polymer obtained from a (meth) acrylic acid alkyl ester-based monomer, a hydroxyl group-containing monomer and / or a carboxyl group-containing monomer, and an isocyanate-based cross-linking agent, and (B). A pressure-sensitive adhesive composition for a polarizing plate containing an ionic solid which is a solid at 25 ° C. is described. According to the pressure-sensitive adhesive composition of the invention according to Patent Document 1, not only the pressure-sensitive adhesive property is excellent, but also the protrusion of the pressure-sensitive adhesive is reduced when a polarizing plate member such as a polarizing film is attached. It is said that the obtained polarizing plate has excellent antifouling properties. However, the surface resistivity of the pressure-sensitive adhesive layer obtained by the pressure-sensitive adhesive composition according to Patent Document 1 is 2.0 × 10 ^{+ 11} Ω / □ or more, and the antistatic performance of the pressure-sensitive adhesive layer is insufficient. there were.
Further, Patent Document 2 describes an aqueous dispersion type acrylic pressure-sensitive adhesive composition containing 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 monomer. An optical pressure-sensitive adhesive composition containing an acrylic polymer copolymerized with a vinyl monomer is described. According to the pressure-sensitive adhesive composition of the invention according to Patent Document 2, it is used for fixing a polarizing film of an image display device, which is required to have excellent environmental friendliness and high functionality, particularly for a small electronic terminal such as a mobile phone. It is said that it can be suitably applied to polarizing film fixing applications such as liquid crystal display devices and organic EL display devices. However, Patent Document 2 does not describe the antistatic performance of the pressure-sensitive adhesive layer at all, and does not make any suggestion.

Japanese Unexamined Patent Publication No. 2009-251281 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.
For this reason, 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 1.0 × 10 ^{+ 9} Ω / □ or less. In the pressure-sensitive adhesive layer related to the above, it has been a very difficult task to exhibit such extremely excellent antistatic performance.
Further, even when such extremely excellent antistatic performance can be exhibited, it is difficult to maintain the antistatic performance of the pressure-sensitive adhesive layer and at the same time maintain the durability of the pressure-sensitive adhesive layer.

The present invention has a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having an extremely excellent antistatic performance having a surface resistivity of the pressure-sensitive adhesive layer of 1.0 × 10 ^{+ 9 Ω / □ or less and not impairing durability.} An object of the present invention is to provide a product and an adhesive film using the product.

The present inventors have earnestly tackled this problem in order to solve the difficult problem of simultaneously achieving both extremely excellent antistatic performance and durability. As a result, the number of carbon atoms of the alkyl group of the alkyl (meth) acrylate constituting the acrylic polymer of the pressure-sensitive adhesive composition is limited to a specific range, and two or more kinds of alkyl (meth) acrylates in a specific combination are copolymerized. A pressure-sensitive adhesive composition containing at least one selected from an alkoxy group-containing vinyl monomer and a nitrogen-containing vinyl monomer and an antistatic agent having a melting point of 25 ° C. or higher. By making it a thing, it became possible to solve this problem.

The present inventors include the acrylic polymer and an ionic compound having a melting point of 25 ° C. or higher and 90 ° C. or lower at a ratio of 10 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the acrylic polymer. A pressure-sensitive adhesive that has extremely excellent antistatic performance as compared with conventional pressure-sensitive adhesive compositions, and can form a pressure-sensitive adhesive layer having excellent durability without precipitation of antistatic agent and deterioration over time. We found that a composition could be obtained and completed the present invention.

The pressure-sensitive adhesive composition according to the present invention has ^{an extremely excellent antistatic performance of 1.0 × 10 + 9} 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 ionic compound having a melting point of 25 ° C. or higher is contained in a proportion of 10 parts by weight or more. As described above, in the present invention, the content of the antistatic agent is significantly increased as compared with the content in the conventional pressure-sensitive adhesive composition so that extremely excellent antistatic performance that cannot be achieved by the prior art can be obtained. There is.
Therefore, after the durability test of the pressure-sensitive adhesive layer in a high-temperature and high-humidity environment, a large amount of the antistatic agent contained in the pressure-sensitive adhesive layer is deposited on the surface of the pressure-sensitive adhesive layer, and the durability is lowered. For the purpose of avoiding the above, the acrylic polymer contained in the pressure-sensitive adhesive composition is mainly composed of n-butyl acrylate (BA), and a monomer having good copolymerizability with BA is selected and copolymerized, and a specific silane is formed. The technical idea is to include a coupling agent.

Further, in order to solve the above problems, the present invention is a pressure-sensitive adhesive composition containing an acrylic polymer, (F) an antistatic agent, and (G) a cross-linking agent, wherein the acrylic polymer is used. Contains (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, and (C) hydroxyl group and / or carboxyl group. At least one selected from at least one copolymerizable vinyl monomer, (D) at least one copolymerizable vinyl monomer containing an aromatic group, and (E) an alkoxy group-containing vinyl monomer and a nitrogen-containing vinyl monomer. An acrylic polymer having a weight average molecular weight of 1 million to 3 million, which is a copolymer obtained by copolymerizing one of the above, as the (F) antistatic agent, an ionic compound having a melting point of 25 ° C. or higher is used as the acrylic. A group consisting of a trifunctional or higher functional isocyanate compound and a bifunctional or higher functional epoxy compound as the (G) cross-linking agent, which is contained in a proportion of 10 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the copolymer. The pressure-sensitive adhesive composition contains at least one cross-linking agent selected from, and the pressure-sensitive adhesive composition further comprises at least one functional group selected from (H) epoxy group, mercapto group, and acid anhydride group. The surface resistance of the pressure-sensitive adhesive layer containing a monomer-type or oligomer-type silane coupling agent containing the above-mentioned pressure-sensitive adhesive composition and cross-linking the pressure-sensitive adhesive composition is 1.0 × 10 ^{+ 9} Ω / □ or less. After 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 in a test environment of 60 ° C. × 90% RH × 750 hr, the pressure-sensitive adhesive layer is subjected to a durability test. Provided is a pressure-sensitive adhesive composition characterized in that the antioxidant is not deposited on the surface.

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 strength of the pressure-sensitive adhesive layer to the non-alkali glass is increased. A 10 cm square plate having a total thickness of 80 μm is bonded to non-alkali glass via an adhesive layer having a thickness of 1.0 to 6.0 N / 25 mm and having a thickness of 20 μm obtained by cross-linking the pressure-sensitive adhesive composition. After subjecting the test piece to a durability test under a test environment of 85 ° C. × 750 hr, or after subjecting it to a durability test under a test environment of 60 ° C. × 90% RH × 750 hr, foaming and peeling It is preferable that there is no such thing.

Copolymerization containing a hydroxyl group as the copolymerizable vinyl monomer containing the hydroxyl group and / or the carboxyl group of (C) with respect to a total of 100 parts by weight of the (A), the (B) and the (D). At least one selected from the group consisting of a possible monomer and a copolymerizable monomer containing a carboxyl group is contained in a proportion of 0.1 to 5 parts by weight, and the copolymerizable product containing the hydroxyl group. Polymers are 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-. The copolymerizable monomer which is at least one selected from the compound group consisting of hydroxymethyl (meth) acrylamide and N-hydroxyethyl (meth) acrylamide and contains the carboxyl group is (meth) acrylic acid. , Carboxyethyl (meth) acrylate, Carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropyl hexahydrophthalic acid, 2- (meth) acryloy Loxyethyl phthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid, carboxypolycaprolactone mono (meth) acrylate, 2- (meth) acryloyloxyethyl tetrahydrophthalic acid It is preferable that at least one selected from the group of compounds consisting of.

At least one selected from the (E) alkoxy group-containing vinyl monomer and nitrogen-containing vinyl monomer is alkoxyalkyl (meth) acrylate, alkoxypolyalkylene glycol mono (meth) acrylate, N-vinyl-substituted lactams, and dialkyl-substituted amino. At least one selected from alkyl (meth) acrylamide, dialkyl-substituted aminoalkyl (meth) acrylate, and dialkyl-substituted (meth) acrylamide, and the above (A), (B), and (D). It is preferable that at least one selected from the (E) alkoxy group-containing vinyl monomer and nitrogen-containing vinyl monomer is contained in a ratio of 1 to 20 parts by weight with respect to 100 parts by weight in total.

The (F) antistatic agent is preferably an ionic compound other than an alkali metal salt having a melting point of 25 ° C. or higher and 90 ° C. or lower.

The initial surface resistivity of the pressure-sensitive adhesive layer and the surface resistivity of the pressure-sensitive adhesive layer after being subjected to a durability test in a test environment of 85 ° C. × 750 hr are both 1.0 × 10 ^{+ 9} Ω / □ or less. Is preferable.

The present invention also provides a pressure-sensitive adhesive film, wherein a 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 an adhesive film for a polarizing plate using the above-mentioned 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, a release film / pressure-sensitive adhesive layer / release film in which a 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 having a structure.

Further, the present invention has a structure in which a 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 the 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 liquid crystal panel characterized in that the above-mentioned polarizing plate with an adhesive layer is used.

According to the present invention, an adhesive having an extremely excellent antistatic performance with a surface resistivity of the adhesive layer of 1.0 × 10 ^{+ 9} Ω / □ or less, which cannot be achieved by the prior art, and which does not impair durability. A pressure-sensitive adhesive composition capable of forming a layer and a pressure-sensitive adhesive film using the same can be provided.
In the present invention, the content of the antistatic agent is remarkably increased as compared with the content in the conventional pressure-sensitive adhesive composition so that extremely excellent antistatic performance that cannot be achieved by the prior art can be obtained. Therefore, in the present invention, after the durability test of the pressure-sensitive adhesive layer in a high-temperature and high-humidity environment, a large amount of the antistatic agent contained in the pressure-sensitive adhesive layer is deposited on the surface of the pressure-sensitive adhesive layer to ensure durability. For the purpose of avoiding deterioration of the properties, the acrylic polymer contained in the pressure-sensitive adhesive composition is mainly composed of n-butyl acrylate (BA), and a monomer having good copolymerizability with BA is selected and copolymerized. , Contains a specific silane coupling agent.

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

The pressure-sensitive adhesive composition of the present embodiment is a pressure-sensitive adhesive composition containing an acrylic polymer, (F) an antioxidant, and (G) a cross-linking agent, and the acrylic polymer is (A) n. Copolymerism containing (C) a hydroxyl group and / or a carboxyl group with at least one selected from the group consisting of −butyl acrylate, (B) t-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, and methyl acrylate. At least one vinyl monomer, at least one copolymerizable vinyl monomer containing (D) an aromatic group, and at least one selected from (E) an alkoxy group-containing vinyl monomer and a nitrogen-containing vinyl monomer. The copolymer is an acrylic polymer having a weight average molecular weight of 1 million to 3 million. As the (F) antistatic agent, an ionic compound having a melting point of 25 ° C. or higher is used as the 100 of the acrylic polymer. It was contained in a proportion of 10 parts by weight or more and 60 parts by weight or less with respect to parts by weight, and was selected as the (G) cross-linking agent from the group consisting of trifunctional or higher functional isocyanate compounds and bifunctional or higher functional epoxy compounds. A monomer containing at least one cross-linking agent, and the pressure-sensitive adhesive composition further containing at least one functional group selected from (H) epoxy group, mercapto group, and acid anhydride group. The pressure-sensitive adhesive layer containing a type or oligomer-type silane coupling agent and having the pressure-sensitive adhesive composition crosslinked has a surface resistance of 1.0 × 10 ^{+ 9} Ω / □ or less, and the pressure-sensitive adhesive layer. After being 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, the surface of the pressure-sensitive adhesive layer is charged. It is characterized in that no inhibitor is deposited.

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. To do. In the pressure-sensitive adhesive composition of the present embodiment, it is preferable that the alkyl (meth) acrylate monomer 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 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. Is preferable. Further, the acrylic polymer is at least 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, the ratio (A) / (B) of (A) and (B) is preferably 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. It is preferable that (C) is contained in a ratio of 0.1 to 5 parts by weight with respect to a total of 100 parts by weight of (A), (B) and (D).

Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) such as 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxyethyl (meth) acrylate. ) Acrylate, and at least one kind of hydroxyl group-containing (meth) acrylamide 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 preferably 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the acrylic polymer, and is 0.1. The ratio is more preferably ~ 4.4 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 or more 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 of the acrylic polymer (it is acceptable even if the carboxyl group-containing monomer is not copolymerized). In the case of copolymerizing a carboxyl group-containing monomer, the ratio is more preferably 0.01 to 2.3 parts by weight, and the ratio is 0.01 to 1.2 parts by weight. This is particularly preferable, and the ratio is most preferably 0.01 to 0.8 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) It is preferable because it has excellent copolymerizability with a monomer.
In order for (D) to be distinguished from (C) and (E), it is preferable that (D) does not contain a hydroxyl group, a carboxyl group, an alkoxy group and nitrogen.

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. It is more preferably contained in a proportion of ~ 28 parts by weight, and particularly preferably contained in a proportion of 6 to 24 parts by weight.

(E) At least one selected from the alkoxy group-containing vinyl monomer and the nitrogen-containing vinyl monomer includes at least one selected from the group consisting of the alkoxy group-containing vinyl monomer and the nitrogen-containing vinyl monomer. That is, only one of the alkoxy group-containing vinyl monomer and the nitrogen-containing vinyl monomer may be selected and copolymerized, or both the alkoxy group-containing vinyl monomer and the nitrogen-containing vinyl monomer may be copolymerized. It is preferable that (E) is contained in a proportion of 1 to 20 parts by weight, and is contained in a proportion of 1 to 18 parts by weight, based on a total of 100 parts by weight of (A), (B) and (D). It is more preferable that it is contained in a proportion of 2 to 16 parts by weight.

In order for (E) to be distinguished from (C), it is preferable that (E) does not contain a hydroxyl group and a carboxyl group. Further, in order for (E) to be distinguished from (D), it is preferable that (E) does not contain an aromatic group. The alkoxy group-containing vinyl monomer may not contain nitrogen, and the nitrogen-containing vinyl monomer may not contain an alkoxy group. (E) may be a vinyl monomer containing an alkoxy group and nitrogen, such as alkoxyalkyl (meth) acrylamide.

Examples of the alkoxy group-containing vinyl monomer include at least one selected from alkoxyalkyl (meth) acrylate and alkoxypolyalkylene glycol mono (meth) acrylate.
Specific examples of alkoxyalkyl acrylates include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-propoxyethyl (meth) acrylate, 2-isopropoxyethyl (meth) acrylate, and 2-butoxyethyl. (Meta) acrylate, 2-methoxypropyl (meth) acrylate, 2-ethoxypropyl (meth) acrylate, 2-propoxypropyl (meth) acrylate, 2-isopropoxypropyl (meth) acrylate, 2-butoxypropyl (meth) acrylate , 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 3-propoxypropyl (meth) acrylate, 3-isopropoxypropyl (meth) acrylate, 3-butoxypropyl (meth) acrylate, 4-methoxy Examples thereof include butyl (meth) acrylate, 4-ethoxybutyl (meth) acrylate, 4-propoxybutyl (meth) acrylate, 4-isopropoxybutyl (meth) acrylate, 4-butoxybutyl (meth) acrylate and the like.
Specific examples of alkoxypolyalkylene glycol mono (meth) acrylate include methoxypolyethylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, ethoxypolypropylene glycol (meth) acrylate, and methoxypolybutylene. Glycol (meth) acrylate, ethoxypolybutylene glycol (meth) acrylate and the like can be mentioned. The alkoxypolyalkylene glycol mono (meth) acrylate is a monomer in which the hydroxyl group at one end of the polyalkylene glycol is an alkyl ether and the hydroxyl group at the other end is a (meth) acrylate.

Examples of the nitrogen-containing vinyl monomer include at least one selected from N-vinyl-substituted lactams, dialkyl-substituted aminoalkyl (meth) acrylamide, dialkyl-substituted aminoalkyl (meth) acrylate, and dialkyl-substituted (meth) acrylamide. Be done.
Examples of N-vinyl-substituted lactams include N-vinyl-2-pyrrolidone, N-vinylcaprolactam, and N-vinyl-2-piperidone.
Examples of the dialkyl-substituted aminoalkyl (meth) acrylamide include dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, and dipropylaminopropyl (meth) acrylamide. Examples thereof include diisopropylaminopropyl (meth) acrylamide, ethylmethylaminopropyl (meth) acrylamide, methylpropylaminopropyl (meth) acrylamide, methylisopropylaminopropyl (meth) acrylamide and the like.
Examples of the dialkyl-substituted aminoalkyl (meth) acrylate include dimethylaminomethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, dimethylaminoisopropyl (meth) acrylate, and dimethylaminobutyl (meth) acrylate. , Diethylaminomethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, ethylmethylaminoethyl (meth) acrylate, methylpropylaminoethyl (meth) acrylate, methylisopropylaminoethyl (meth) acrylate, dibutylaminoethyl (meth) acrylate, Examples thereof include t-butylaminoethyl (meth) acrylate.
Dialkyl-substituted (meth) acrylamides include dimethyl (meth) acrylamide, diethyl (meth) acrylamide, dipropylacrylamide, diisopropyl (meth) acrylamide, dibutyl (meth) acrylamide, ethylmethyl (meth) acrylamide, and methylpropyl (meth) acrylamide. , Methylisopropyl (meth) acrylamide and the like.

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 million to 3 million.

The pressure-sensitive adhesive composition according to the present embodiment contains (F) an antistatic agent in order to obtain antistatic performance. (F) The antistatic agent preferably contains an ionic compound having a melting point of 25 ° C. or higher and 90 ° C. or lower at a ratio of 10 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the acrylic polymer. , 16 to 40 parts by weight is more preferable, and 16 to 38 parts by weight is particularly preferable. This antistatic agent is an ionic compound composed of an anion and a 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 90 ° C., which is solid at a temperature of 25 ° C., and particularly preferably an ionic compound having a melting point of 25 ° C. to 50 ° C. ..

Examples of the anion contained in the (F) antistatic agent include an inorganic or organic anion. The inorganic _{^{anion, PF 6 -, AsF 6 -}} , SbF 6 -, BF 4 -, AlF 4 -, (FSO 2) 2 N -, FSO 3 -, SCN -, ClO 4 -, and the like. The organic anion, sulfonate anion (RSO ₃ ^-), carboxylate anion (RCOO ^-), alkoxide or phenoxide anion (RO ^-), organic imide anion _(R 2 N ^-), methide _(R 3 C ^-) anions, organic An anion having an organic group can be mentioned as at least one or more of R in a borate (R ₄ B ^{−) anion 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, it may have a bond between the two or more Rs to form a ring. It is preferable that the organic group R contains a fluorine atom (fluoro group). Among them, pentafluorobenzene sulfonate, hexafluorophosphate, bis (trifluoromethanesulfonyl) imide, bis (fluorosulfonyl) imide, triflate, nonaflate butane sulfonate, tetrakispentafluorophenylborate, tris (pentafluorobenzenesulfonyl) methide. It is preferably one selected from the group consisting of.

Examples of the cation contained in the (E) antistatic agent include pyridinium cation, imidazolium cation, pyrimidinium cation, pyrazolium cation, pyrrolidinium cation, ammonium cation, phosphonium cation, sulfonium cation and the like. A cation having an organic group of 1 to 4 is preferable, and a quaternary ammonium cation (R ₄ N ⁺ ) having an organic group R at least in a nitrogen atom, an N-substituted pyridinium cation, an N-substituted imidazolium cation and the like are 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 two or more Rs, it may have a bond between the two or more Rs to form a ring.

The pressure-sensitive adhesive composition according to the present embodiment further contains, as the (G) cross-linking agent, at least one or more cross-linking agents selected from the group consisting of trifunctional or higher functional isocyanate compounds and bifunctional or higher functional epoxy compounds. .. The ratio of the (G) cross-linking agent contained in the pressure-sensitive adhesive composition according to the present embodiment is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the acrylic polymer. The ratio is more preferably 01 to 3 parts by weight, and particularly preferably 0.01 to 0.8 parts by weight.

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 body with a trivalent or higher-valent polyol.
Examples of the bifunctional or higher functional epoxy compound include glycols 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 this embodiment further contains (H) a silane coupling agent. The (H) 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. The (H) silane coupling agent contains at least one functional group selected from an epoxy group, a mercapto group, and an acid anhydride group. As the (H) 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 contained in the pressure-sensitive adhesive composition according to the present embodiment is preferably 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-epylcyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane, 2- (3,4-epylcyclohexyl) ethylmethyldiethoxysilane, 2- (3,4-Epylcyclohexyl) ethyltriethoxysilane, 5,6-epoxyhexyltrimethoxysilane, 5,6-epoxyhexylmethyldimethoxysilane, 5,6-epoxyhexylmethyldiethoxysilane, 5,6- Examples thereof include epoxyhexyltriethoxysilane. 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 anhydride and 3-triethoxysilylpropyl succinic anhydride. Further, an oligomerized alkoxy oligomer (silicone alkoxy oligomer) can also be used as a silane coupling agent.

The pressure-sensitive adhesive composition of the present embodiment contains, as arbitrary components, 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 1.0 × 10 + 9} Ω / □ or less, and is 9.0 × 10 ^{+ 8} Ω / □ or less. Is more preferable, and 6.0 × 10 ^{+ 8} 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 1.0 × 10 + 9} Ω / □ or less, and 9.0 × 10 ^{+ 8} Ω /. It is more preferably □ or less, and particularly preferably ^{6.0 × 10 + 8 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 obtained by cross-linking 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 (F) 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.
Regarding the antistatic performance of the (F) antistatic agent in the pressure-sensitive adhesive composition of the present embodiment, two or more samples of the pressure-sensitive adhesive layer obtained by cross-linking the same pressure-sensitive adhesive composition were prepared, and one sample was prepared at 85 ° C. × 750 hr. After being subjected to the durability test under the test environment of (F), 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 ( F) The antistatic agent may not be precipitated.

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.
The performance of the pressure-sensitive adhesive composition of the present embodiment without foaming and peeling is that 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, and no foaming or peeling after being subjected to the durability test in a 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 base material 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 release treatment with a silicone-based or fluorine-based release agent or the like on the surface of the pressure-sensitive adhesive layer that is 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, or an antistatic agent on the opposite side of the resin film from the side on which the 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 combining 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, the release films on both sides are peeled off sequentially or at the same time to expose the adhesive surface, so that the release films can be bonded 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 polarizing plates. In particular, it may be used for bonding a polarizing plate and an 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 an 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 adhesive layer include "release film / adhesive layer / polarizing plate", "release film / adhesive layer / polarizing plate / adhesive layer / release film", and "polarized film". Examples include "plate / adhesive layer" and "adhesive layer / polarizing plate / adhesive layer". These laminated configurations may be included as a partial structure of the 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 pipe, and the air in the reactor was replaced with nitrogen gas. Then, a solvent (ethyl acetate) was added to the reactor 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, 15 parts by weight of benzyl acrylate, and 15 parts by weight of methoxyethyl acrylate. ) Was added. 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 6 and Comparative Examples 1 to 3]
Acrylics used in Examples 2 to 6 and Comparative Examples 1 to 3 in the same manner as in Example 1 above, except that the composition of the monomers is as shown in (A) to (E) of Table 1. 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 6 and Comparative Examples 1 to 3 is in the range of 1 million to 3 million.

<Manufacturing of adhesive film>
[Example 1]
With respect to the acrylic polymer solution of Example 1 produced as described above, 20 parts by weight of the tetrabutylammonium triflate salt, 0.1 parts by weight of the cross-linking agent (D-110N), and a silane coupling agent (KBM-) were added. 403) was added at a ratio of 0.05 parts by weight, and the mixture was 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. The solvent was removed by this. Then, by aging for 7 days in an atmosphere of 23 ° C. and 50% RH, a pressure-sensitive adhesive layer in which the pressure-sensitive adhesive composition is crosslinked is provided on one side of the release film, and the release film / pressure-sensitive adhesive layer / The adhesive film of Example 1, which is the composition of the release film, was obtained.
[Examples 2 to 6 and Comparative Examples 1 to 3]
Examples 2 to 6 and Comparative Examples 1 to 3 are the same as those of the above-mentioned adhesive film of Example 1 except that the compositions of the additives are as described in (F) to (H) of Table 1. Adhesive film was obtained.

In Table 1, the numerical value added after the abbreviation of each component indicates the part by weight. The total of (A), (B) and (D) is calculated as 100 parts by weight. Table 2 shows the compound names of the abbreviations of each component used in Table 1. 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 (silicone resin coated PET film) was peeled off from the pressure-sensitive adhesive films of Examples 1 to 6 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 Inc.) 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”. Then, the peeling strength when peeled at a speed 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 Analytech). 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 the measurement of adhesive strength. Then, the test piece 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, and then in a 23 ° C. × 50% RH atmosphere. After 1 hour, the state of the pressure-sensitive adhesive layer was visually observed to determine the durability.
The criteria for determining durability are as follows.
○ ・ ・ 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 the measurement of adhesive strength. Then, the test piece 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, and then in 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.
The criteria for determining the state of precipitation of the antistatic agent were as follows.
○ ・ ・ 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 6 had an adhesive force against non-alkali glass of 1.0 to 6.0 N / 25 mm. The initial surface resistivity of the pressure-sensitive adhesive layer and the surface resistivity of the pressure-sensitive adhesive layer after the durability test in a test environment of 85 ° C. × 750 hr were both 1.0 × 10 ^{+ 9} Ω / □ or less. Further, after the durability test in the test environment of 85 ° C. × 750 hr and the durability test in the test environment of 60 ° C. × 90% RH × 750 hr, there is no foaming or peeling, and the durability is maintained. 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 6 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. At least one selected from the vinyl monomer and the (E) alkoxy group-containing vinyl monomer and the nitrogen-containing 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, since the pressure-sensitive adhesive film of Comparative Example 1 had a higher content ratio of the (F) antistatic agent than that of Comparative Example 3, the surface resistivity of the pressure-sensitive adhesive layer became a low value, but after the durability test, , The antistatic agent was deposited on the surface of the pressure-sensitive adhesive layer.

In the pressure-sensitive adhesive film of Comparative Example 2, at least one selected from the (E) alkoxy group-containing vinyl monomer and the nitrogen-containing vinyl monomer was not copolymerized with the acrylic polymer. Although it contains (H) a 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 precipitated 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 (H) 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 (F) 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 The surface resistivity became a high value.

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, an adhesive having an extremely excellent antistatic performance with a surface resistivity of the adhesive layer of 1.0 × 10 ^{+ 9} Ω / □ or less, which cannot be achieved by the prior art, and which does not impair durability. A pressure-sensitive adhesive composition capable of forming a layer and a pressure-sensitive adhesive film using the same can be provided. Therefore, the pressure-sensitive adhesive film using the pressure-sensitive adhesive composition according to the present invention has extremely excellent antistatic performance and durability as a pressure-sensitive adhesive film for bonding a polarizing plate and a liquid crystal panel. Therefore, it has great industrial utility value.

Claims (6)

A pressure-sensitive adhesive composition containing an acrylic polymer, (F) an antistatic agent, and (G) a cross-linking agent.
The acrylic polymer
(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
(E) At least one selected from an alkoxy group-containing vinyl monomer and a nitrogen-containing vinyl monomer, and
Is an acrylic polymer having a weight average molecular weight of 1 to 3 million.
As the (F) antistatic agent, an ionic compound having a melting point of 25 ° C. or higher is contained in a proportion of 10 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the acrylic polymer.
As the (G) 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 (H) epoxy group, mercapto group, and acid anhydride group. Become
The surface resistivity of the pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition is 1.0 × 10 ^{+ 9} Ω / □ or less.
After 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 in a test environment of 60 ° C. × 90% RH × 750 hr, the pressure-sensitive adhesive layer is subjected to a durability test. A pressure-sensitive adhesive composition, wherein the antistatic agent is not deposited on the surface. 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). The pressure-sensitive adhesive composition according to claim 1, wherein () is 1.0 to 17.8. 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 or 2 on one side of the resin film. An adhesive film for a polarizing plate using the adhesive film according to claim 3. 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 or 2 crosslinked on one side of the release film having a thickness of 1 μm to 25 μm. An adhesive film characterized by its composition. A liquid crystal panel characterized in that a polarizing plate with a pressure-sensitive adhesive layer is used in which a pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition according to claim 1 or 2 is laminated on one side of the polarizing plate.