JP6925487B2 - Adhesive layer and antistatic surface protective film - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive composition containing an antistatic agent and an antistatic surface protective film. More particularly, the present invention is, as an antistatic agent, a pressure-sensitive adhesive composition containing a borate anion compound having a pentafluorophenyl group (C ₆ F ₅ group), have a superior adhesive properties and antistatic performance Further, the present invention relates to a pressure-sensitive adhesive composition capable of obtaining a pressure-sensitive adhesive layer having excellent low-staining property, and an antistatic surface protective film using the pressure-sensitive adhesive composition. Further, the present invention has excellent adhesion to the low refractive index layer formed by using the composition for forming a low refractive index layer containing a fluorine compound, in which the adherend is laminated on the surface of the optical film. It is an object of the present invention to provide an adhesive composition capable of obtaining an adhesive layer having performance and antistatic performance and also excellent in low stain resistance, and an antistatic surface protective film using the adhesive composition.

When manufacturing and transporting optical films such as polarizing plates, retardation plates, lens films for displays, antireflection films, hard coat films, transparent conductive films for touch panels, and optical products such as displays using them. A surface protective film is attached to the surface of the optical film to prevent the surface from being soiled or scratched in a subsequent step. The appearance inspection of the optical film, which is an optical product, may be performed with the surface protective film attached to the optical film in order to save the trouble of peeling off the surface protective film and reattaching the optical film to improve work efficiency.

Conventionally, a surface protective film having an adhesive layer provided on one side of a base film has been generally used in the manufacturing process of an optical product in order to prevent the adhesion of scratches and stains. The surface protective film is attached to the optical film via an adhesive layer having a slight adhesive strength. The reason why the adhesive layer has a slight adhesive strength is that when the used surface protective film is peeled off from the surface of the optical film and removed, the adhesive layer can be easily peeled off, and the adhesive is the optics of the product as an adherend. This is to prevent the film from adhering to the film and remaining (so-called adhesive residue is prevented).

In recent years, in the production process of a display panel, a driver IC or the like for controlling the display screen of the display panel by a peeling band voltage generated when the surface protective film bonded on the optical film is peeled off and removed. Although the number of occurrences is small, the phenomenon that the circuit parts of the above are destroyed and the phenomenon that the orientation of the liquid crystal molecule is damaged are occurring.
Further, in order to reduce the power consumption of the display panel, the drive voltage is getting lower, and the breaking voltage of the driver IC is also getting lower accordingly. Therefore, when the surface protective film is peeled from the optical film which is the adherend, in order to prevent a problem due to a high peeling band voltage, an adhesive layer containing an antistatic agent for suppressing the peeling band voltage is provided. The surface protective film used has been proposed.

Further, in recent years, in order to prevent adhesion of stains, fingerprints, etc. on display panels and touch panels, a layer containing a fluorine compound has been provided on the surface.
For example, in Patent Documents 1 and 2, the low refractive index layer provided on the outermost surface of the antireflection film has hollow inorganic particles for imparting low refractive index and curable fluorine for imparting antifouling property. An antireflection film and a polarizing plate in which a resin is blended are described.
Further, Patent Document 3 includes a reflection having a low refractive index layer composed of perfluoroalkyl (meth) acrylate, modified polydimethylsiloxane having an acrylic group, a fluorine-containing compound having a polymerizable double bond, and hollow silica particles. A protective film is described.

Further, in Patent Document 4, a functional layer formed by a treatment using a fluorine-containing compound or a silicon-containing compound is used as an adherend, and fluorine or silicon is used in a surface protective film attached to the adherend. As the compound contained, a surface protective film including a polyether-modified polyorganosiloxane, a fluorine-based surfactant containing a fluorine-containing alkyl group, and an acrylic pressure-sensitive adhesive layer externally provided with an acrylic polymer containing fluorine or silicon is described. Has been done.

JP-A-2010-277059 Japanese Unexamined Patent Publication No. 2008-262187 JP-A-2015-55659 Japanese Unexamined Patent Publication No. 2011-63712

In an antistatic surface protective film in which the surface protective film has antistatic performance, it is essential to add an antistatic agent to the pressure-sensitive adhesive layer. Therefore, when the content of the antistatic agent contained in the pressure-sensitive adhesive layer is increased in order to enhance the antistatic performance of the pressure-sensitive adhesive layer, an antistatic surface protective film is attached to the adherend via the pressure-sensitive adhesive layer. When this happens, the amount of antistatic agent adhering to the adherend increases, which causes the adherend to become contaminated. Therefore, there is a trade-off between the antistatic performance and the low pollution property to the adherend. That is, it was difficult to improve the low pollution property while maintaining the antistatic function. However, in recent years, the image quality and quality of display panels have been improved, and the evaluation criteria for low pollution have become more stringent. An excellent antistatic surface protective film is required.

The present invention has been made in view of the above circumstances, and is a pressure-sensitive adhesive composition capable of obtaining a pressure-sensitive adhesive layer having excellent adhesive performance and antistatic performance, and also having excellent low-staining property. An object of the present invention is to provide an antistatic surface protective film using the same.

The inventors of the present application limit the number of carbon atoms of the alkyl group of the alkyl (meth) acrylate constituting the main component of the acrylic polymer of the pressure-sensitive adhesive composition to a specific range, and two or more kinds of alkyl (meth) of a specific combination. ) It is a technical idea of the present invention to use an antioxidant containing a borate anion having a pentafluorophenyl group in combination with a copolymer obtained by copolymerizing an acrylate. The pressure-sensitive adhesive composition based on this technical idea has excellent pressure-sensitive and antistatic performance as compared with the conventional pressure-sensitive adhesive composition for surface protective film, and further has excellent low-staining property. The present invention was completed by finding that the pressure-sensitive adhesive composition obtained the above.
That is, in the antistatic surface protective film formed by using the pressure-sensitive adhesive composition according to the present invention, the adherend is an antifouling layer containing a fluorine compound or a fluorine compound laminated on the surface of the optical film. It has excellent adhesive performance and antistatic performance with respect to the low refractive index layer formed by using the composition for forming a low refractive index layer containing the above, and is also excellent in low stain resistance. Achieves both antistatic performance and low pollution.

That is, the present invention is a pressure-sensitive adhesive composition containing an acrylic polymer, an antioxidant, and a cross-linking agent, wherein the acrylic polymer has (A) an alkyl group having C1 to C18 carbon atoms. With respect to a total of 100 parts by weight of the meta) acrylic acid ester monomer, 1 to 50 parts by weight of at least one (meth) acrylic acid ester monomer having (a1) alkyl groups having C1 to C4 carbon atoms and (a2). At least one of the (meth) acrylic acid ester monomers having an alkyl group having C5 to C18 is in a proportion of 50 to 99 parts by weight, and among the above (a2), isooctyl (meth) acrylate and isononyl (meth). ) At least one selected from the group consisting of acrylate and 2-ethylhexyl (meth) acrylate is contained in a proportion of 50 parts by weight or more, and further, as a copolymerizable monomer group, (B) hydroxyl group and / or carboxyl It is an acrylic polymer of a copolymer obtained by copolymerizing at least one kind of copolymerizable vinyl monomer containing a group and at least one kind of (C) polyalkylene glycol mono (meth) acrylic acid ester monomer. the (D) an antistatic agent, a borate anion having a pentafluorophenyl group (C ₆ F ₅ group), a compound that consists of cations, melting point be ionic compound which is solid at a temperature 25 ° C. above 25 ° C. The ionic compound is contained as an essential component in a ratio of 0.1 to 10 parts by weight with respect to 100 parts by weight of the acrylic polymer, and the pressure-sensitive adhesive composition further comprises (E) a cross-linking accelerator. F) Provided is a pressure-sensitive adhesive composition comprising a ketoenol copolymer compound.

It is preferable that the cation of the ionic compound is one selected from the cation group consisting of pyridinium, imidazolium, sulfonium, phosphonium, pyrrolidinium, guanidinium, ammonium, isouronium, thiouronium, piperidinium, pyrazolium, methylium, lithium and ammonium. ..

The copolymerizable monomer containing the (B) hydroxyl group is 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, or 2-hydroxyethyl (meth) acrylate. , N-Hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, at least one selected from the group of compounds, and the (B) carboxyl group. The copolymerizable monomers containing the above are (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, and 2- (meth) acrylic. Loyloxypropyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid, carboxypolycaprolactone mono (meth) ) At least one selected from the group of compounds consisting of acrylate and 2- (meth) acryloyloxyethyl tetrahydrophthalic acid is preferable.

As the (C) polyalkylene glycol mono (meth) acrylic acid ester monomer, the average number of repetitions of the alkylene oxide constituting the polyalkylene glycol chain is 3 to 14, and the diester content in the monomer is 0.2% or less. , At least one selected from polyalkylene glycol mono (meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, and ethoxypolyalkylene glycol (meth) acrylate, based on 100 parts by weight of the acrylic polymer. Therefore, it is preferably contained in a proportion of 1 to 50 parts by weight.

The (E) cross-linking accelerator is at least one selected from the group consisting of an aluminum chelate compound, a titanium chelate compound, and an iron chelate compound, and the above (E) is based on 100 parts by weight of the acrylic polymer. E) The cross-linking accelerator was contained in an amount of 0.001 to 0.5 parts by weight and the (F) ketoenol tether compound was contained in an amount of 0.1 to 300 parts by weight. The weight-to-weight ratio of (E) is preferably 70 to 1000.

The present invention also provides a pressure-sensitive adhesive film in which a pressure-sensitive adhesive layer obtained by cross-linking the above-mentioned pressure-sensitive adhesive composition is laminated.

Peeling of the pressure-sensitive adhesive layer from a low-refractive index layer formed by using a composition for forming a low-refractive index layer having ^{a surface resistivity of 1.0 × 10 + 12 Ω / □ or less and containing a fluorine compound.} The band voltage is preferably ± 0.3 kV or less.

The present invention also provides an antistatic surface protective film using the above-mentioned adhesive film.

The present invention also provides an antistatic surface protective film for a polarizing plate using the above-mentioned adhesive film.

The present invention also provides an optical film with an adhesive in which an adhesive layer made of the above-mentioned adhesive composition is laminated on at least one surface of the optical film.

In the above-mentioned pressure-sensitive adhesive film, it is preferable that one side of the resin film is subjected to antistatic treatment and antifouling treatment on the side opposite to the side on which the pressure-sensitive adhesive layer is formed.

According to the present invention, there is provided an adhesive composition capable of obtaining an adhesive layer having excellent adhesive performance and antistatic performance and also excellent in low contamination property, and an antistatic surface protective film using the same. can do.

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

The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition containing an acrylic polymer, an antistatic agent, and a cross-linking agent. With respect to a total of 100 parts by weight of the (meth) acrylic acid ester monomer of C18, at least one kind of (meth) acrylic acid ester monomer having (a1) alkyl groups having C1 to C4 has 1 to 50 parts by weight. (A2) At least one of the (meth) acrylic acid ester monomers having an alkyl group having C5 to C18 in a proportion of 50 to 99 parts by weight, and the isooctyl (meth) acrylate among the above (a2). At least one selected from the group consisting of isononyl (meth) acrylate and 2-ethylhexyl (meth) acrylate is contained in a proportion of 50 parts by weight or more, and further, as a copolymerizable monomer group, (B) hydroxyl group and / Or an acrylic copolymer of a copolymer obtained by copolymerizing at least one copolymerizable vinyl monomer containing a carboxyl group and at least one (C) polyalkylene glycol mono (meth) acrylic acid ester monomer. a polymer, wherein (D) an antistatic agent, a borate anion having a pentafluorophenyl group (C ₆ F ₅ group), a compound that consists of cations, the ionic melting point of the solid at a temperature 25 ° C. above 25 ° C. It is a compound, and the ionic compound is contained as an essential component in a ratio of 0.1 to 10 parts by weight with respect to 100 parts by weight of the acrylic polymer, and the pressure-sensitive adhesive composition further comprises (E) a cross-linking accelerator. And (F) ketoenol copolymer compound.

Among the (meth) acrylic acid ester monomers having (A) alkyl groups having C1 to C18 carbon atoms, at least one of the (a1) alkyl group carbon atoms (meth) acrylic acid ester monomers having C1 to C4 carbon atoms is selected as one. Examples thereof include butyl (meth) acrylate, isobutyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and isopropyl (meth) acrylate.
Further, examples of the (meth) acrylic acid ester monomer having (a2) alkyl groups having C5 to C18 carbon atoms include pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, and isooctyl. (Meta) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (Meta) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, myristyl (meth) acrylate, isomyristyl (meth) acrylate, cetyl ( Examples thereof include meta) acrylate, isosetyl (meth) acrylate, stearyl (meth) acrylate, and isostearyl (meth) acrylate.

In the acrylic polymer, the (a1) alkyl group has a carbon number of C1 to C4 (meth) with respect to a total of 100 parts by weight of the (meth) acrylic acid ester monomer having an alkyl group having a carbon number of C1 to C18. ) At least one kind of acrylic acid ester monomer is 1 to 50 parts by weight, and (a2) at least one kind of (meth) acrylic acid ester monomer having C5 to C18 carbon atoms is 50 to 99 parts by weight. It is more preferable that at least one of the above (a1) is contained in an amount of 3 to 45 parts by weight and at least one of the above (a2) is contained in a proportion of 55 to 97 parts by weight. It is particularly preferable that at least one of the above (a1) is contained in an amount of 5 to 45 parts by weight and at least one of the above (a2) is contained in an amount of 55 to 95 parts by weight, and at least one of the above (a1) is contained. It is most preferable that one type is contained in an amount of 8 to 40 parts by weight and at least one type of (a2) is contained in an amount of 60 to 92 parts by weight.

In the acrylic polymer, among the above (a2), isooctyl (meth) acrylate and isononyl (a2) with respect to a total of 100 parts by weight of the (meth) acrylic acid ester monomer having (A) alkyl groups having C1 to C18 carbon atoms. It is preferable that at least one selected from the group consisting of meta) acrylate and 2-ethylhexyl (meth) acrylate is contained in a proportion of 50 parts by weight or more, more preferably 50 to 99 parts by weight, and 55 to 97 parts by weight. Is more preferable, 55 to 95 parts by weight is particularly preferable, and 60 to 92 parts by weight is most preferable.

(B) As at least one kind of copolymerizable vinyl monomer containing a hydroxyl group and / or a carboxyl group, at least one kind of copolymerizable vinyl monomer containing a hydroxyl group may be used, and the copolymerizable vinyl monomer containing a carboxyl group may be used. It may be at least one of. Alternatively, at least one kind of copolymerizable vinyl monomer containing a hydroxyl group and at least one kind of copolymerizable vinyl monomer containing a carboxyl group may be used in combination. Further, at least one kind of copolymerizable vinyl monomer containing a hydroxyl group and a carboxyl group may be used.

Examples of the copolymerizable monomer (B) containing a hydroxyl group include hydroxyalkyl (meth) acrylates and hydroxyl group-containing (meth) acrylamides. Specific examples of these include 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, and N-hydroxy (meth) acrylamide. , N-Hydroxymethyl (meth) acrylamide, preferably at least one selected from the compound group consisting of N-hydroxyethyl (meth) acrylamide. These (B) hydroxyl group-containing copolymerizable monomers do not have a polyalkylene glycol chain, unlike the (C) polyalkylene glycol mono (meth) acrylic acid ester monomer described later.
It is preferable that the total of at least one or more copolymerizable monomers containing (B) a hydroxyl group is contained in a ratio of 0.1 to 20 parts by weight with respect to 100 parts by weight of the acrylic polymer. The proportion of 5 to 15 parts by weight is more preferable, the proportion of 2.0 to 14.0 parts by weight is particularly preferable, and the proportion of 2.5 to 12.0 parts by weight is most preferable.

Examples of the copolymerizable monomer containing the (B) carboxyl group include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, and the like. 2- (Meta) acryloyloxypropyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid, It is preferably at least one selected from the group of compounds consisting of carboxypolycaprolactone mono (meth) acrylate and 2- (meth) acryloyloxyethyl tetrahydrophthalic acid.
It is preferable that the total of at least one or more copolymerizable monomers containing the (B) carboxyl group is contained in a proportion of 0.0 to 1.0 parts by weight with respect to 100 parts by weight of the acrylic polymer. , 0.0 to 0.8 parts by weight is more preferable, 0.0 to 0.5 parts by weight is particularly preferable, and 0.0 to 0.3 parts by weight is most preferable.
The acrylic polymer may not contain a copolymerizable monomer containing a carboxyl group (ratio is 0.0 parts by weight) as the (B) copolymerizable vinyl monomer containing a hydroxyl group and / or a carboxyl group. The ratio of a copolymerizable monomer containing a carboxyl group is preferably 0.01 to 1.0 parts by weight, preferably 0.05 to 0.8 parts by weight, based on 100 parts by weight of the acrylic polymer. By weight is more preferable, 0.05 to 0.5 parts by weight is particularly preferable, and 0.05 to 0.3 parts by weight is most preferable.

The (C) polyalkylene glycol mono (meth) acrylic acid ester monomer may be a compound in which one of the plurality of hydroxyl groups of the polyalkylene glycol is esterified as a (meth) acrylic acid ester. Since the (meth) acrylic acid ester group becomes a polymerizable group, it can be copolymerized with the acrylic polymer. The other hydroxyl group may be OH as it is, or may be an alkyl ether such as methyl ether or ethyl ether, a saturated carboxylic acid ester such as an acetate ester, or the like.
Examples of the alkylene group contained in the polyalkylene glycol include, but are not limited to, an ethylene group, a propylene group, and a butylene group. The polyalkylene glycol may be a copolymer of two or more kinds of polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol. Examples of the copolymer of polyalkylene glycol include polyethylene glycol-polypropylene glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, polyethylene glycol-polypropylene glycol-polybutylene glycol, and the like. It may be a block copolymer or a random copolymer.
The polyalkylene glycol mono (meth) acrylic acid ester monomer (C) preferably has an average number of repetitions of alkylene oxides constituting the polyalkylene glycol chain of 3 to 14. The "average number of repetitions of alkylene oxide" is the average number of repetitions of the alkylene oxide unit in the portion of the "polyalkylene glycol chain" contained in the molecular structure of the (C) polyalkylene glycol mono (meth) acrylic acid ester monomer. be.
In the (C) polyalkylene glycol mono (meth) acrylic acid ester monomer, the diester content in the monomer is preferably 0.2% or less. The "diester content in the monomer" is the content (% by weight) of the polyalkylene glycol di (meth) acrylic acid ester contained in the (C) polyalkylene glycol mono (meth) acrylic acid ester monomer.

The polyalkylene glycol mono (meth) acrylic acid ester monomer (C) was selected from polyalkylene glycol mono (meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, and ethoxypolyalkylene glycol (meth) acrylate. It is preferably at least one kind.
More specifically, polyethylene glycol-mono (meth) acrylate, polypropylene glycol-mono (meth) acrylate, polybutylene glycol-mono (meth) acrylate, polyethylene glycol-polypropylene glycol-mono (meth) acrylate, polyethylene glycol-poly. Butylene glycol-mono (meth) acrylate, polypropylene glycol-polybutylene glycol-mono (meth) acrylate, polyethylene glycol-polyethylene glycol-polybutylene glycol-mono (meth) acrylate; methoxypolyethylene glycol- (meth) acrylate, methoxypolyethylene glycol -(Meta) acrylate, methoxypolyethylene glycol- (meth) acrylate, methoxy-polyethylene glycol-polypropylene glycol- (meth) acrylate, methoxy-polyethylene glycol-polybutylene glycol- (meth) acrylate, methoxy-polyethylene glycol-polybutylene Glycol- (meth) acrylate, methoxy-polyethylene glycol-polypropylene glycol-polybutylene glycol- (meth) acrylate; ethoxypolyethylene glycol- (meth) acrylate, ethoxypolyethylene glycol- (meth) acrylate, ethoxypolybutylene glycol- (meth) Acrylate, ethoxy-polyethylene glycol-polyethylene glycol- (meth) acrylate, ethoxy-polyethylene glycol-polybutylene glycol- (meth) acrylate, ethoxy-polyethylene glycol-polybutylene glycol- (meth) acrylate, ethoxy-polyethylene glycol-polypropylene glycol -Polybutylene glycol- (meth) acrylate and the like.
It is preferable that the total of at least one or more of the (C) polyalkylene glycol mono (meth) acrylic acid ester monomers is contained in a ratio of 1 to 50 parts by weight with respect to 100 parts by weight of the acrylic polymer. It is more preferably contained in a proportion of about 40 parts by weight, particularly preferably in a proportion of 1 to 30 parts by weight, and most preferably in a proportion of 2 to 25 parts by weight.

(D) As an antistatic agent _{, an ionic compound consisting of a borate anion having a pentafluorophenyl group (C 6} F ₅ groups) and a cation and having a melting point of 25 ° C. or higher and a solid at a temperature of 25 ° C. is an essential component. Include as. Borate anions having a pentafluorophenyl group (C ₆ F _{5 ) include (C 6} F ₅ ) ₄ B ⁻ , (C ₆ F ₅ ) ₃ (C ₆ H ₅ ) B ⁻ , (C ₆ F ₅ ). ₂ (C ₆ H ₅ ) ₂ B ⁻ , (C ₆ F ₅ ) (C ₆ H ₅ ) ₃ B ⁻ , and the like can be mentioned.

Examples of the cation of the ionic compound include nitrogen-containing onium cations such as pyridinium, imidazolium, pyrimidinium, pyrazolium, pyrrolidinium and ammonium, onium cations such as phosphonium cation and sulfonium cation, carbocation such as methylium, and alkali metal cations such as lithium. Can be mentioned. Among them, one selected from the cation group consisting of pyridinium, imidazolium, sulfonium, phosphonium, pyrrolidinium, guanidinium, ammonium, isouronium, thiouronium, piperidinium, pyrazolium, methylium, lithium, ammonium and the like is preferable. When these cations are organic cations, the organic cations can have one or more substituents. Examples of the substituent of the organic cation include an aliphatic group such as an alkyl group and an aromatic group such as a phenyl group.
(D) As the antistatic agent, it is preferable to contain the ionic compound in a ratio of 0.1 to 10 parts by weight with respect to 100 parts by weight of the acrylic polymer.

(D) Specific examples of the ionic compound that can be used as an antistatic agent include triphenylmethylium tetrakis (pentafluorophenyl) borate salt, 1-nonylpyridinium tetrakis (pentafluorophenyl) borate salt, and 1-octylpyridinium tetrakis. (Pentafluorophenyl) borate salt, 1-dodecylpyridinium tetrakis (pentafluorophenyl) borate salt, lithium tetrakis (pentafluorophenyl) borate salt, 2-methyl-1-dodecylpyridinium tetrakis (pentafluorophenyl) borate salt, etc. Can be mentioned.

The (E) cross-linking accelerator may be a substance that functions as a catalyst for the reaction (cross-linking reaction) between the acrylic polymer and the cross-linking agent when the polyisocyanate compound is used as the cross-linking agent, and is a tertiary amine. Examples thereof include amine compounds such as, metal chelate compounds, organotin compounds, organolead compounds, and organometallic compounds such as organozinc compounds. In the present invention, a metal chelate compound or an organic tin compound is preferable as the cross-linking accelerator.

The metal chelate compound is a compound in which one or more polydentate ligands L are bonded to the central metal atom M. The metal chelate compound may or may not have one or more bidentate ligands X that bind to the metal atom M. For example, when the general formula of a metal chelate compound having one metal atom M is _{represented by M (L) m} (X) _n , m ≧ 1 and n ≧ 0. When m is 2 or more, m L may be the same ligand or may be different ligands. When n is 2 or more, n Xs may be the same ligand or different ligands.

Examples of the metal atom M include Fe, Ni, Mn, Cr, V, Ti, Ru, Zn, Al, Zr, Sn and the like.
Examples of the polydentate ligand L include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetic acid, lauryl acetoacetic acid, and stearyl acetoacetic acid, and acetylacetone (also known as 2,4-pentandione). Examples thereof include β-diketones such as 2,4-hexanedione and benzoylacetone. These are keto-enol tautomeric compounds and may be enol-deprotonated enolates (eg, acetylacetonate) in the polydentate ligand L.
The monodentate ligand X includes halogen atoms such as chlorine atom and bromine atom, pentanoyl group, hexanoyl group, 2-ethylhexanoyl group, octanoyl group, nonanoyl group, decanoyyl group, dodecanoyl group, octadecanoyl group and other acyloxy. Examples thereof include an alkoxy group such as a group, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group and a butoxy group.

Specific examples of the metal chelate compound include tris (2,4-pentandionato) iron (III), iron trisacetylacetonate, titaniumtrisacetylacetonate, rutheniumtrisacetylacetonate, zinc bisacetylacetonate, and aluminum tris. Acetylacetonate, Zirconite Tetrakis Acetylacetonate, Tris (2,4-Hexanedionate) Iron (III), Bis (2,4-Hexane Zionato) Zinc, Tris (2,4-Hexane Zionato) Titanium, Tris Examples thereof include (2,4-hexane dionat) aluminum and tetrakis (2,4-hexane dionate) zirconium.

Examples of the organic tin compound include dialkyltin oxide, a fatty acid salt of dialkyltin, and a fatty acid salt of first tin. Conventionally, dibutyltin compounds have been widely used, but in recent years, the problem of toxicity of organotin compounds has been pointed out, and in particular, tributyltin (TBT) contained in dibutyltin compounds is also a concern as an endocrine disruptor. From the viewpoint of safety, a long-chain alkyl tin compound such as a dioctyl tin compound is preferable. Specific examples of the organic tin compound include dioctyl tin oxide and dioctyl tin dilaurate. Sn compounds can be used provisionally, but in the future, in view of the trend that the use of safer substances is required, Al, Ti, Fe, etc., which are safer than Sn, etc. It is preferable to use a metal chelate compound.
The (E) cross-linking accelerator in the pressure-sensitive adhesive composition according to the present invention is preferably at least one selected from the group consisting of an aluminum chelate compound, a titanium chelate compound, and an iron chelate compound.
The cross-linking accelerator (E) is preferably contained in a proportion of 0.001 to 0.5 parts by weight with respect to 100 parts by weight of the acrylic polymer.

(F) Examples of the ketoenol tether compound include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetic acid, lauryl acetoacetic acid, and stearyl acetoacetic acid, and acetylacetone and 2,4-hexanedione. , Β-diketone such as benzoylacetone. In a pressure-sensitive adhesive composition using a polyisocyanate compound as a cross-linking agent, these prevent excessive increase in viscosity and gelation of the pressure-sensitive adhesive composition after blending the cross-linking agent by blocking the isocyanate group contained in the cross-linking agent. , The pot life of the adhesive composition can be extended.
The keto-enol tautomer compound is preferably contained in a ratio of 0.1 to 300 parts by weight with respect to 100 parts by weight of the acrylic polymer.

Since the (F) keto-enol tautomer compound has an effect of suppressing cross-linking as opposed to the (E) cross-linking accelerator, the ratio of the (F) keto-enol tautomer compound to the (E) cross-linking accelerator Is preferably set appropriately. In order to prolong the pot life of the pressure-sensitive adhesive composition and improve the storage stability, the weight ratio of (F) / (E) is preferably 70 to 1000, more preferably 70 to 700. It is preferably 80 to 600, and particularly preferably 80 to 600.

In the pressure-sensitive adhesive composition of the present invention, the pressure-sensitive adhesive polymer is cross-linked when the pressure-sensitive adhesive layer is formed. As a method for causing the cross-linking reaction, cross-linking may be performed by photo-cross-linking such as ultraviolet rays (UV), but it is preferable that the pressure-sensitive adhesive composition contains a cross-linking agent.
Examples of the cross-linking agent include a bifunctional or trifunctional or higher functional isocyanate compound, a bifunctional or trifunctional or higher functional epoxy compound, a bifunctional or trifunctional or higher acrylate compound, and a metal chelate compound. Of these, polyisocyanate compounds (bifunctional or trifunctional or higher functional isocyanate compounds) are preferable.
The cross-linking agent is preferably contained in a ratio of 0.1 to 5 parts by weight with respect to 100 parts by weight of the acrylic polymer.

The bifunctional or higher functional isocyanate compound may be at least one or more selected from polyisocyanate compounds having at least two or more isocyanate (NCO) groups in one molecule. Polyisocyanate compounds are classified into aliphatic isocyanates, aromatic isocyanates, acyclic isocyanates, alicyclic isocyanates, and the like, but any of them may be used. Specific examples of the polyisocyanate compound include aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and trimethylhexamethylene diisocyanate (TMDI), diphenylmethane diisocyanate (MDI), and xylylene diisocyanate (XDI). , Aromatic isocyanate compounds such as hydrogenated xylylene diisocyanate (H6XDI), dimethyldiphenylenediocyanate (TOID), and tolylene diisocyanate (TDI).

Examples of the trifunctional or higher functional isocyanate compound include a bullet-modified compound of a bifunctional isocyanate compound (a compound having two NCO groups in one molecule), an isocyanurate-modified compound, and trivalent or higher valents such as trimethylolpropane (TMP) and glycerin. Adduct (modified polyol) with the polyol (compound having at least 3 or more OH groups in one molecule) and the like.
As the bifunctional or higher functional isocyanate compound, it is also possible to use only the trifunctional isocyanate compound or only the bifunctional isocyanate compound. It is also possible to use a trifunctional isocyanate compound and a bifunctional isocyanate compound in combination.

As the bifunctional isocyanate compound, an acyclic aliphatic isocyanate compound, which is produced by reacting a diisocyanate compound with a diol compound, can also be used. For example, a diisocyanate compound has a general formula "O = C = N-X-N = C = O" (where X is a divalent group), and a general formula "HO-Y-OH" (where Y is a divalent group). ) Represents a diol compound, and examples of the compound produced by reacting the diisocyanate compound with the diol compound include a compound represented by the following general formula Z.

[General formula Z]
O = C = N-X- (NH-CO-O-YO-O-CO-NH-X) _n- N = C = O

Here, n is an integer of 0 or more. When n is 0, the general formula Z represents "O = C = N-X-N = C = O". The bifunctional acyclic aliphatic isocyanate compound may contain a compound in which n is 0 in the general formula Z (diisocyanate compound which has not reacted with the diol compound), but a compound in which n is an integer of 1 or more is an essential component. It is preferable to include as. The bifunctional acyclic aliphatic isocyanate compound may be a mixture composed of a plurality of compounds having different n in the general formula Z.

The diisocyanate compound represented by the general formula "O = C = N-X-N = C = O" is an aliphatic diisocyanate. X is preferably an acyclic and aliphatic divalent group. The aliphatic diisocyanate preferably comprises one or more selected from the compound group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate.

The diol compound represented by the general formula "HO-Y-OH" is an aliphatic diol. Y is preferably an acyclic and aliphatic divalent group. Examples of the diol compound include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, and 2-ethyl-2. -From a group of compounds consisting of butyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxypivalate, polyethylene glycol, and polypropylene glycol. It preferably consists of one or more selected species.

Further, as other components, the pressure-sensitive adhesive composition according to the present invention includes a surfactant, a curing accelerator, a plasticizer, a filler, a curing retarder, a processing aid, an antioxidant, an antioxidant, and a polyether modification. A known additive such as a siloxane compound can be appropriately blended. These can be used alone or in combination of two or more.

The acrylic polymer used in the pressure-sensitive adhesive composition of the present invention comprises (A) an (meth) acrylic acid ester monomer having an alkyl group having C1 to C18 carbon atoms, and (a1) having an alkyl group having C1 to C4 carbon atoms. As a group of monomers copolymerizable with at least one (meth) acrylic acid ester monomer and at least one (meth) acrylic acid ester monomer having (a2) alkyl groups having C5 to C18 carbon atoms, B) By copolymerizing at least one kind of copolymerizable vinyl monomer containing a hydroxyl group and / or a carboxyl group with at least one kind of (C) polyalkylene glycol mono (meth) acrylic acid ester monomer. Can be synthesized. The polymerization method of the acrylic polymer is not particularly limited, and an appropriate polymerization method such as solution polymerization or emulsion polymerization can be used.

When producing an acrylic polymer, it is preferable to carry out the polymerization reaction under anhydrous conditions such as solution polymerization using an anhydrous organic solvent in order to reduce the mixing of water into the pressure-sensitive adhesive composition. In particular, since the (C) polyalkylene glycol mono (meth) acrylic acid ester monomer has high hydrophilicity, it is preferable to use one having a low water content.
Each monomer used in the production of the acrylic polymer reduces the amount of polyfunctional (more than bifunctional) monomer that can function as a cross-linking agent as much as possible in order to avoid an increase in viscosity of the pressure-sensitive adhesive composition. Is preferable. In particular, as the (C) polyalkylene glycol mono (meth) acrylic acid ester monomer, since the corresponding diester content is a di (meth) acrylic acid ester of a bifunctional monomer, it is preferable to use one having a low diester content.

The pressure-sensitive adhesive composition of the present invention comprises the above-mentioned acrylic polymer, a cross-linking agent, (D) an antistatic agent, (E) a cross-linking accelerator, (F) a keto-enol tautomer compound, and optionally any of them. It can be prepared by blending an additive.

The adhesive layer formed by cross-linking the pressure-sensitive adhesive composition has an adhesive force of 0.05 to 0.1 N / 25 mm at a low peeling speed of 0.3 m / min and a high peeling speed of 30 m / min. The adhesive strength is preferably 1.0 N / 25 mm or less. As a result, it is possible to obtain a performance in which the adhesive strength does not change much depending on the peeling speed, and it is possible to quickly peel even by high-speed peeling. Further, since it is reattached, even when the antistatic surface protective film is once peeled off, it does not require an excessive force and can be easily peeled off from the adherend.

The gel fraction of the pressure-sensitive adhesive layer (the pressure-sensitive adhesive after cross-linking) formed by cross-linking the pressure-sensitive adhesive composition of the present invention is preferably 95 to 100%. Due to such a high gel fraction, the adhesive strength does not become excessive at a low peeling speed, the elution of unpolymerized monomers or oligomers from the acrylic polymer is reduced, and low pollution and high temperature / high temperature are achieved. Durability in humidity is improved, and contamination of the adherend can be suppressed.

Since the pressure-sensitive adhesive composition of the present invention contains the above-mentioned components (A) to (F) in a well-balanced manner, it has excellent antistatic performance, and has a low peeling speed and a high peeling speed. It has an excellent balance of adhesive strength and is also excellent in low pollution. Therefore, it can be suitably used as an antistatic surface protective film for an optical film such as a polarizing plate, an optical film with an adhesive, and the like, and thus has high industrial utility value.

The pressure-sensitive adhesive film of the present invention is formed by laminating a pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition of the present invention on at least one side of a resin film. The antistatic surface protective film of the present invention is made of the adhesive film of the present invention, and can be suitably used as an antistatic surface protective film for an optical film such as a polarizing plate or an optical member. In the optical film with an adhesive of the present invention, an adhesive layer made of the adhesive composition of the present invention is laminated on at least one surface of the optical film.

As the polarizing plate that is the adherend of the pressure-sensitive adhesive layer, a polarizing plate (LR polarizing plate) having a low reflectance surface treatment of 2% or less, and a low-reflection surface treatment having a reflectance of 2% or less are applied. Moreover, a polarizing plate (AG-LR polarizing plate) which has been subjected to antiglare treatment can be mentioned. Further, the optical film such as a polarizing plate and the optical member have a low refractive index layer and fluorine formed by using a composition for forming a low refractive index layer containing a fluorine compound on the outermost surface to which the pressure-sensitive adhesive layer is bonded. It can have a surface layer such as an antifouling layer containing a compound.
Examples of the composition for forming a low refractive index layer (surface layer) containing a fluorine compound include a fluororesin composition. In order to reduce the refractive index of the low refractive index layer, the composition for forming the low refractive index layer may contain hollow particles such as hollow silica particles. Examples of the refractive index of the low refractive index layer include 1.2 to 1.4. The low-refractive-index surface treatment may have a high-refractive index layer having a higher refractive index than the low-refractive index layer on the surface under the low-refractive index layer. Examples of the refractive index of the high refractive index layer include 1.5 to 1.9. A medium refractive index layer having a refractive index intermediate between the low refractive index layer and the high refractive index layer may be laminated.

The surface resistivity of the pressure-sensitive adhesive layer formed by cross-linking the pressure-sensitive adhesive composition ^{is preferably 1.0 × 10 + 12} Ω / □ or less. Further, the pressure-sensitive adhesive layer is peeled off after being bonded to a low-refractive index layer (antifouling layer) formed by using a composition for forming a low-refractive index layer containing a fluorine compound via the pressure-sensitive adhesive layer. It is preferable that the peeling band voltage at the time of this is "± 0.3 kV or less". In the present invention, "± 0.3 kV or less" means 0 to −0.3 kV and 0 to + 0.3 kV, that is, −0.3 to + 0.3 kV. If the surface resistivity is large, the performance of releasing static electricity generated by charging when the adhesive layer is peeled from the adherend is inferior. Therefore, by sufficiently reducing the surface resistivity, the peeling band voltage generated by the static electricity generated when the adherend peels off the adhesive layer is reduced, which affects the electric control circuit of the adherend. Can be suppressed.

As the base film of the pressure-sensitive adhesive layer and the release film (separator) for protecting the pressure-sensitive adhesive surface, a resin film such as a polyester film can be used. The release film is 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 that is combined with the adhesive surface.
The resin film to be the base film may be subjected to antistatic treatment and antifouling treatment on the surface opposite to the side on which the pressure-sensitive adhesive layer is formed. Examples of the antistatic treatment of the resin film include antistatic treatment by applying or kneading an antistatic agent. Examples of the antifouling treatment of the resin film include antifouling treatment with a silicone-based or fluorine-based mold release agent, a coating agent, silica fine particles, or the like.

Next, the present invention will be further described with reference to Examples.

<Manufacturing of adhesive composition>
[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, 15 parts by weight of methyl acrylate, 85 parts by weight of 2-ethylhexyl acrylate, 15.0 parts by weight of 8-hydroxyoctyl acrylate, 0.1 part by weight of acrylic acid, and 20 parts by weight of polypropylene glycol monoacrylate (n = 12) were added to the reaction apparatus. 60 parts by weight of a solvent (ethyl acetate) was added together with the parts. 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 an acrylic polymer solution having a weight average molecular weight of 500,000 and used in Example 1. Obtained. To this acrylic polymer solution, 9.0 parts by weight of acetylacetone was added and stirred, and then 2.0 parts by weight of coronate HX (isocyanurate compound of hexamethylene diisocyanate compound) and 0.1 parts by weight of titanium trisacetylacetonate were added. , 0.9 part by weight of triphenylmethylium tetrakis (pentafluorophenyl) borate salt was added, and the mixture was stirred and mixed to obtain the pressure-sensitive adhesive composition of Example 1.

[Examples 2 to 6 and Comparative Examples 1 to 3]
The pressure-sensitive adhesive compositions of Examples 2 to 6 and Comparative Examples 1 to 3 are the same as those of Example 1 except that the composition of the pressure-sensitive adhesive composition of Example 1 is as shown in Tables 1 and 2, respectively. I got something.

In both Table 1 and Table 2, the numerical values of the parts by weight obtained by assuming that the total of the group (a1) and the group (a2) is 100 parts by weight are shown in parentheses. The compound names of the abbreviations of the respective components used in Tables 1 and 2 are shown in Tables 3 and 4. Coronate (registered trademark) HX, HL and L are trade names of Tosoh Corporation, and Takenate (registered trademark) D-140N, D-127N and D-110N are trade names of Mitsui Chemicals, Inc. ..

Regarding the (C) polyalkylene glycol mono (meth) acrylic acid ester monomer in Table 3, the numerical value of "n" is the average number of repetitions of the alkylene oxide constituting the polyalkylene glycol chain. In C-1 to C-5 used in Examples 1 to 6, the average number of repetitions of the alkylene oxide constituting the polyalkylene glycol chain was 3 to 14, and the diester content in the monomer was 0.2% or less. be. The diester content in the monomer of C-6 is 0.8%.

Regarding the (D) antistatic agent in Table 4, D-1 to D-5 used in Examples 1 to 6 are ionic compounds having a melting point of 25 ° C. or higher and a solid at a temperature of 25 ° C. D-6 is an ionic compound having a melting point of 15 ° C. and a liquid at a temperature of 25 ° C.

<Synthesis of bifunctional isocyanate compound>
The bifunctional isocyanate compounds of Synthesis Examples 1 and 2 were synthesized by the following methods. As shown in Tables 5 and 6, the diisocyanate and the diol compound were mixed at a molar ratio of NCO / OH = 16, reacted at 120 ° C. for 3 hours, and then under reduced pressure using a thin film evaporator. The unreacted diisocyanate was removed to obtain the desired bifunctional isocyanate compound.

<Manufacturing of antistatic surface protective film>
[Example 1]
The pressure-sensitive adhesive composition of Example 1 produced as described above is applied onto a release film made of a polyethylene terephthalate (PET) film coated with a silicone resin, and then dried at 90 ° C. to remove the solvent to remove the pressure-sensitive adhesive. An adhesive sheet having a layer thickness of 25 μm was obtained. After that, the adhesive sheet is transferred to the surface opposite to the antistatic and antifouling treated polyethylene terephthalate (PET) film on one surface, and "antistatic and antifouling treated". An antistatic surface protective film of Example 1 having a laminated structure of "PET film / adhesive layer / release film (PET film coated with silicone resin)" was obtained.
[Examples 2 to 6 and Comparative Examples 1 to 3]
The antistatic surface protective films of Examples 2 to 6 and Comparative Examples 1 to 3 were obtained in the same manner as the antistatic surface protective film of Example 1 described above.

<Test method and evaluation>
The antistatic surface protective films of Examples 1 to 6 and Comparative Examples 1 to 3 were aged at 23 ° C. and 50% RH for 7 days, and then the release film (silicone resin coated PET film) was peeled off. The surface resistivity measurement sample was obtained by exposing the pressure-sensitive adhesive layer.
Further, the antistatic surface protective film on which the pressure-sensitive adhesive layer was exposed was attached to the surface of the polarizing plate via the pressure-sensitive adhesive layer, left for 1 day, and then autoclaved at 50 ° C., 5 atm, and 20 minutes. Those left at room temperature for an additional 12 hours were used as measurement samples for adhesive strength, peeling zone voltage, and low contamination. The polarizing plate of the adherend is an LR polarizing plate or an AG-LR polarizing plate, and is formed by using a composition for forming a low refractive index layer, which is subjected to a low reflection surface treatment and contains a fluorine compound on the surface. It has a low refractive index layer.

<Adhesive strength>
The measurement sample obtained above (a 25 mm wide antistatic surface protective film adhered to the surface of the polarizing plate of the adherend) was peeled at a low peeling speed (a low speed) in the 180 ° direction using a tensile tester. Peeling was performed at 0.3 m / min) and a high peeling speed (30 m / min), and the measured peel strength was defined as the adhesive strength (N / 25 mm).

<Surface resistivity>
After aging, before affixing to the polarizing plate of the adherend, the release film (PET film coated with silicone resin) is peeled off to expose the adhesive layer, and the resistance meter Hiresta UP-HT450 (Mitsubishi Chemical Analytech) The surface resistance (Ω / □) of the pressure-sensitive adhesive layer was measured using (manufactured by).

<Peeling band voltage>
When the measurement sample obtained above is peeled 180 ° at a tensile speed of 30 m / min, the voltage (voltage band) generated by charging the polarizing plate of the adherend is measured by the high-precision electrostatic sensor SK-035. , SK-200 (manufactured by Keyence Co., Ltd.), and the maximum value of the measured value was defined as the peeling band voltage (kV).

<Low pollution>
The polarizing plate of the adherend was bonded onto one side of the glass plate using a bonding machine via an adhesive layer such as a double-sided adhesive tape. Then, the pressure-sensitive adhesive layer of the antistatic surface protective film was bonded to the surface of the polarizing plate of the adherend using a bonding machine. After storage for a period of 3 days and 30 days in an environment of 23 ° C. and 50% RH, the antistatic surface protective film is peeled off, and the contaminated state of the surface of the polarizing plate of the adherend is visually observed. bottom.
The low-staining property is "○" when the surface of the polarizing plate of the adherend is not contaminated in both the 3-day storage and the 30-day storage, and is slight in either the 3-day storage or the 30-day storage. The case of contamination was evaluated as "Δ", and the case of contamination was evaluated as "x".

Table 7 shows the evaluation results. The surface resistivity is expressed by a method in which "m × 10 ^{+ n} " is set to "mE + n" (where m is an arbitrary real number and n is a positive integer). "Surface treatment of polarizing plate" indicates the type of polarizing plate of the adherend (LR treatment or AG-LR treatment).

The antistatic surface protective film of Examples 1 to 6 is subjected to LR treatment or AG-LR treatment, and has a low refractive index layer containing a fluorine compound on the surface, and is applied to an adherend of the polarizing plate of the adherend. On the other hand, the adhesive strength at a low speed peeling speed of 0.3 m / min is 0.05 to 0.1 N / 25 mm, and the adhesive strength at a high speed peeling speed of 30 m / min is 1.0 N / 25 mm or less. The surface resistivity was 1.0 × 10 ⁺¹² Ω / □ or less, the peeling band voltage was ± 0.3 kV or less, and it was excellent in low pollution during storage for 3 days and 30 days.
That is, the antistatic surface protective film of the present invention has excellent adhesive performance and antistatic performance on the adherend, and is also excellent in low pollution. Achieved both.

Further, the acrylic polymer does not contain (a1) a (meth) acrylic acid ester monomer having an alkyl group having C1 to C4 carbon atoms, and (D) an antistatic agent has a melting point of 15 ° C. and a temperature of 25 ° C. The antistatic surface protective film of Comparative Example 1, which is a liquid ionic compound, had a high peeling zone voltage and was slightly inferior in low pollution.
Further, in the acrylic polymer, the (a1) alkyl group has a carbon number of C1 to C4 (a1) with respect to a total of 100 parts by weight of the (meth) acrylic acid ester monomer having an alkyl group having a carbon number of C1 to C18. It contains 80 parts by weight of a meta) acrylic acid ester monomer, contains more than 20 parts by weight of a (meth) acrylic acid ester monomer having (a2) alkyl groups having C5 to C18 carbon atoms, and (D) antistatic. The antistatic surface protective film of Comparative Example 2 in which the agent is an ionic compound having a melting point of 15 ° C. and a liquid at a temperature of 25 ° C. has excessive adhesive strength, high surface resistance, and high peeling zone voltage. Moreover, the low pollution property was inferior.
Further, the antistatic surface protective film of Comparative Example 3 in which the acrylic polymer does not contain (C) a polyalkylene glycol mono (meth) acrylic acid ester monomer and the pressure-sensitive adhesive composition does not contain (D) an antistatic agent. The surface resistivity was high, the peeling band voltage was high, and the low pollution property was inferior.
As described above, the antistatic surface protective films of Comparative Examples 1 to 3 could not achieve both excellent low contamination property on the adherend and excellent antistatic performance.

Claims (4)

A pressure-sensitive adhesive layer obtained by cross-linking a pressure-sensitive adhesive composition containing an acrylic polymer, an antistatic agent, and a cross-linking agent.
The acrylic polymer
(A) With respect to a total of 100 parts by weight of the (meth) acrylic acid ester monomer having an alkyl group having C1 to C18 carbon atoms.
(A1) At least one kind of (meth) acrylic acid ester monomer having C1 to C4 carbon atoms of the alkyl group is added to 1 to 50 parts by weight.
(A2) At least one of the (meth) acrylic acid ester monomers having an alkyl group having C5 to C18 and a ratio of 50 to 99 parts by weight.
Furthermore, as a group of copolymerizable monomers,
(B) At least one copolymerizable vinyl monomer containing a hydroxyl group and / or a copolymerizable vinyl monomer containing a carboxyl group.
(C) At least one or more polyalkylene glycol mono (meth) acrylic acid ester monomers and
It is an acrylic polymer of a copolymer obtained by copolymerizing the above.
The copolymerizable vinyl monomer containing the (B) hydroxyl group is 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, or 2-hydroxyethyl (meth) acrylate. , N-Hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, at least one selected from the group of compounds.
The (D) antistatic agent is _{an ionic compound composed of a borate anion having a pentafluorophenyl group (C 6} F ₅ groups) and a cation, and having a melting point of 25 ° C. or higher and a solid at a temperature of 25 ° C.
The pressure-sensitive adhesive composition contains 0.1 to 5 parts by weight of a bifunctional or trifunctional or higher functional isocyanate compound and 0.1 to 5 parts by weight of the ionic compound as the cross-linking agent with respect to 100 parts by weight of the acrylic polymer. It is contained in a proportion of 10 parts by weight,
A pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive composition further contains (E) a cross-linking accelerator and (F) a keto-enol tautomer compound. The cation of the ionic compound is one selected from the cation group consisting of pyridinium, imidazolium, sulfonium, phosphonium, pyrrolidinium, guanidinium, ammonium, isouronium, thiouronium, piperidinium, pyrazolium, methylium, lithium and ammonium. The pressure-sensitive adhesive layer according to claim 1. An antistatic surface protective film, characterized in that the pressure-sensitive adhesive layer according to claim 1 or 2 is laminated on one side of the resin film. An antistatic surface protective film for a polarizing plate using the antistatic surface protective film according to claim 3.