KR20230002182A - Adhesive composition - Google Patents

Abstract

The present invention provides an adhesive composition, an adhesive film using the same, and a surface protective film, which has excellent adhesion performance with adhesive force balanced in terms of a low exfoliation speed and a high exfoliation speed and is capable of promoting compatibility between electrification prevention performance and anti-fouling performance. The adhesive film of the present invention comprises: (F) an electrification prevention agent, or an ionic compound having a melting point of 25 to 80 ℃ and represented by chemical formula (1) K^＋·A^－, wherein K^＋ is a cation and A^－ is an anion selected from a group consisting of a trifluoromethane sulfonate anion not including an imide group and a pentafluoroethane sulfonate anion; and an acryl-based polymer having the glass transition temperature of 0 ℃ or less, wherein 0.01-10 parts by weight of the ionic compound are included based on 100 parts by weight of the acryl-based polymer.

Description

Adhesive composition {ADHESIVE COMPOSITION}

The present invention relates to an adhesive composition containing an antistatic agent, an adhesive film using the same, and a surface protection film. More specifically, at a low peeling speed and a high peeling speed, a pressure-sensitive adhesive composition capable of achieving both antistatic performance and anti-fouling performance as well as excellent adhesive performance, such as having balanced adhesive strength, and an adhesive film using the same, It relates to providing a surface protection film.

Conventionally, in the manufacturing process of optical members, such as a polarizing plate which is a member which comprises a liquid crystal display, the surface protection film for temporarily protecting the surface of an optical member is bonded together. This surface protection film is used only in the process of manufacturing the optical member, and is peeled off and removed from the optical member at the time of mounting the optical member to the liquid crystal display. Since the surface protection film for protecting the surface of such an optical member is used only in the manufacturing process of an optical member, it may be generally called a process film.

In the surface protection film used in the process of manufacturing the optical member in this way, an adhesive layer is formed on one side of an optically transparent polyethylene terephthalate (PET) resin film. In order to protect the pressure-sensitive adhesive layer until the surface protection film is bonded to the optical member, the release film subjected to the release treatment is bonded to the surface of the pressure-sensitive adhesive layer.

Then, optical members such as polarizing plates are subject to product inspections accompanied by optical evaluations such as display ability, color, contrast, contamination of foreign substances, etc. of the liquid crystal display panel in a state where the surface protection film is bonded. For this reason, as a required performance with respect to a surface protection film, it is requested|required that air bubbles, foreign matter, and the low molecular weight component of an adhesive composition do not adhere to an adhesive layer, ie, having antifouling performance.

Further, when peeling the surface protection film from an optical member such as a polarizing plate, there is a concern that peeling electrification caused by static electricity generated when the pressure-sensitive adhesive layer and the adherend are separated may affect the failure of the electric control circuit of the liquid crystal display. For this reason, it is calculated|required that the adhesive layer of a surface protection film has excellent antistatic performance.

Furthermore, in recent years, acrylic resins such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), etc. in addition to triacetyl cellulose (TAC) conventionally used as a polarizer protective layer (sometimes called a protective film) of a polarizing plate. Adoption of materials that easily generate peeling electrification when peeling off the surface protection film of a polarizing plate, such as polyester-based resins, cyclic olefin-based polymers, and polycarbonates, is expanding. For this reason, it is required that the antistatic performance required for the pressure-sensitive adhesive layer for surface protection films of polarizing plates is superior to that of the prior art.

Moreover, when finally peeling a surface protection film from optical members, such as a polarizing plate, what can peel quickly is calculated|required. In order to be able to peel quickly even by so-called high-speed peeling, it is required that the adhesive force has little change depending on the peeling speed.

In this way, in recent years, for the pressure-sensitive adhesive layer constituting the surface protection film, (1) having a balance of adhesive strength at a low peeling rate and a high peeling speed, (2) having a stain resistance performance, (3) excellent charging What has prevention performance etc. is requested|required from the point of ease of use in using a surface protection film.

However, with respect to the required performance of the pressure-sensitive adhesive layer constituting the surface protection film, even if these individual required performances of (1) to (3) can be satisfied, respectively, (1) required for the pressure-sensitive adhesive layer of the surface protection film It has been a very difficult subject to simultaneously satisfy all of the required performances of to (3).

In order to solve these problems, for example, (1) having a balance of adhesive force at a low peeling rate and a high peeling rate, (2) having a stain resistance performance, and (3) having an excellent antistatic performance. For each, the following proposals are known.

(1) Regarding the balance of the adhesive strength at the low peeling rate and the high-speed peeling rate, a copolymer of a (meth)acrylic acid alkyl ester having an alkyl group having 7 or less carbon atoms and a carboxyl group-containing copolymer compound as a main component is used as a crosslinking agent In the acrylic pressure-sensitive adhesive layer formed by crosslinking with , there was a problem that the adhesion of the pressure-sensitive adhesive to the adherend side occurred when adhered for a long period of time, and the adhesive strength to the adherend increased with time. In order to avoid this, it is known that a pressure-sensitive adhesive layer is formed by using a copolymer of a (meth)acrylic acid alkyl ester having an alkyl group having 8 to 10 carbon atoms and a copolymerizable compound having an alcoholic hydroxyl group, and crosslinking the copolymer with a crosslinking agent ( Patent Document 1).

In addition, a pressure-sensitive adhesive layer obtained by mixing a small amount of a copolymer of an alkyl (meth)acrylic acid ester and a copolymerizable compound containing a carboxyl group in the same copolymer as above, and crosslinking the copolymer with a crosslinking agent has been proposed. However, when these are used for surface protection such as a plastic plate having a smooth surface due to their low surface tension, they cause peeling phenomena such as lifting due to heating during processing or storage, or when peeling at high speed in the manual field. There was also a problem that the peelability was poor.

In order to solve these problems, a) 100 parts by weight of (meth)acrylic acid alkyl ester containing a (meth)acrylic acid alkyl ester having an alkyl group having 8 to 10 carbon atoms as a main component, b) 1 to 15 parts by weight of a carboxyl group-containing copolymerizable compound and c) a copolymer of a monomer mixture formed by adding 3 to 100 parts by weight of a vinyl ester of an aliphatic carboxylic acid having 1 to 5 carbon atoms, and a crosslinking agent equivalent or more to the carboxyl group of component b). It has been proposed (Patent Document 2).

The pressure-sensitive adhesive composition described in Patent Literature 2 does not cause peeling phenomena such as lifting during processing or storage, and has excellent re-peelability with a small increase in adhesive strength over time, even when stored for a long period of time, particularly in a high-temperature atmosphere. It is said that it can be re-peeled with a small force, and no adhesive residue is generated on the adherend at that time, and that it can be re-peeled with a small force even when high-speed peeling is performed.

However, in the PSA composition described in Patent Literature 2, since the gel fraction of the PSA layer in Examples 1 to 3 is 90%, unpolymerized monomers or oligomers are easily eluted from the copolymer. In addition, Patent Document 2 does not describe antistatic performance and antifouling performance, and when a material that easily causes peeling electrification is used as an adherend, there is a problem that it is difficult to obtain a pressure-sensitive adhesive layer having excellent antistatic performance and antifouling performance. there was.

In addition, (2) for those having stain resistance, 0 part by mass or more and less than 0.5 part by mass of a carboxyl group-containing monomer, 0.6 to 9 parts by mass of a hydroxyl group-containing (meth)acrylic monomer, and 99.4 to 90.5 parts by mass of a (meth)acrylic acid ester monomer. 100 parts by mass of a (meth)acrylic copolymer having a weight average molecular weight of 100,000 or more and less than 1,000,000; And a pressure-sensitive adhesive composition containing 0.1 to 5 parts by mass of a carbodiimide-based crosslinking agent is disclosed (Patent Document 3).

The pressure-sensitive adhesive composition described in Patent Literature 3 is characterized in that a carbodiimide-based crosslinking agent is used as a crosslinking agent for a (meth)acrylic copolymer having a specific composition. As a result, a cross-linked structure capable of following shrinkage due to pressure and temperature during autoclave treatment can be formed in the pressure-sensitive adhesive layer. For this reason, it is said that the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition described in Patent Document 3 can suppress/prevent foaming even under high-temperature and high-pressure conditions (at the time of autoclave treatment), has excellent stain resistance, and is also excellent in transparency. has been

However, in the adhesive composition described in Patent Literature 3, although stain resistance is improved, it has not been realized to achieve both excellent adhesive performance and antistatic performance, and remains as a problem to be further solved.

Further, (3) Regarding those having excellent antistatic performance, a method of incorporating an antistatic agent into a base film is known as a method for imparting antistatic properties to a surface protection film. As the antistatic agent, for example, (a) various cationic antistatic agents having cationic groups such as quaternary ammonium salts, pyridinium salts, primary to tertiary amino groups, (b) sulfonate groups, sulfate ester base groups, phosphoric acid Anionic antistatic agents having anionic groups such as ester bases and phosphonate groups, (c) amphoteric antistatic agents such as amino acids and aminosulfuric acid esters, (d) amino alcohols, glycerin, and polyethylene glycols. An antistatic agent of warm nature, (e) a high molecular weight antistatic agent obtained by converting the above antistatic agent to a high molecular weight, and the like are disclosed (Patent Document 4).

However, in the surface protection film described in Patent Document 4, although there is a description of imparting antistatic performance related to the adhesion of foreign matter to an adherend, there is no description of a means for achieving both excellent adhesion performance and stain resistance performance. It remains as an issue to be addressed.

In recent years, it has been proposed to incorporate an antistatic agent into a base film, or to directly incorporate an antistatic agent into an adhesive layer without applying it to the surface of a base film. For example, an antistatic pressure-sensitive adhesive composition is disclosed in which a salt having an anion having a fluoro group and a sulfonyl group is dispersed in a dissolved state in a polyether ester plasticizer containing a polyether group in the main chain. (Patent Document 5).

In the pressure-sensitive adhesive composition described in Patent Document 5, an ester formed from a mono- or dicarboxylic acid having a saturated or unsaturated acyclic hydrocarbon group as a plasticizer and an alcohol having an acyclic hydrocarbon group having 1 to 20 carbon atoms, or The use of plasticizers consisting of esters in which the unsaturated groups are epoxidized is disclosed. The mono- or dicarboxylic acid having such a saturated or unsaturated acyclic hydrocarbon group has a carbon number close to that of the acrylic monomer constituting the acrylic copolymer used in the pressure-sensitive adhesive layer, so that the antistatic pressure-sensitive adhesive composition has good compatibility, Plasticizer Since the plasticizer is preferably maintained in the acrylic antistatic pressure-sensitive adhesive composition, it is said that bleed-out is suppressed.

However, in the antistatic pressure-sensitive adhesive composition described in Patent Document 5, there is a disclosure of antistatic performance and improved technology for bleed-out, but description of the point that an excellent adhesive performance such as a balance of adhesive force in a low-speed peeling rate and a high-speed peeling rate can be obtained However, the problem of obtaining a pressure-sensitive adhesive composition having excellent adhesive performance remains.

Japanese Unexamined Patent Publication No. 63-225677 Japanese Unexamined Patent Publication No. 11-256111 Japanese Unexamined Patent Publication No. 2011-122054 Japanese Unexamined Patent Publication No. 11-070629 Japanese Unexamined Patent Publication No. 2014-118469

As described above, with respect to the pressure-sensitive adhesive layer constituting the surface protection film, (1) having a balance of adhesive force at a low peeling rate and a high peeling rate, (2) having a stain resistance performance, (3) excellent antistatic No prior art can be found that simultaneously solves having the performance.

Further, in a pressure-sensitive adhesive layer conventionally formed using a pressure-sensitive adhesive composition having antistatic performance and a surface protection film using the same, the antistatic performance and the stain resistance to an adherend are in a trade-off relationship, and the antistatic performance It was difficult to improve the fouling resistance performance while maintaining it.

Furthermore, in recent years, since the types of adherend materials to which surface protection films are bonded have increased, and the surface treatment of adherends has also been varied, it is more difficult to simultaneously express stain resistance and antistatic performance for all adherends. are losing

The present invention was made in view of the above circumstances, and has excellent adhesive performance, such as having balanced adhesive strength at low peeling rates and high peeling rates, as well as an adhesive composition capable of achieving both antistatic performance and stain resistance performance, and We make it a subject to provide the adhesive film and surface protection film which used it.

The inventors of the present invention, as an antistatic agent, a pressure-sensitive adhesive composition containing an ionic compound that is solid at room temperature and has a trifluoromethanesulfonate anion or pentafluoroethanesulfonate anion with a melting point of 25 to 80 ° C. It was found that antistatic performance and antifouling performance could be simultaneously expressed, and the present invention was completed.

As an antistatic agent of the present invention, an adhesive composition containing an ionic compound solid at room temperature having a trifluoromethanesulfonate anion or a pentafluoroethanesulfonate anion having a melting point of 25 to 80° C., and an adhesive film using the same, and surface protection The film can achieve both excellent adhesion performance, antistatic performance and antifouling performance, and solves the problems of the prior art.

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 (C) a crosslinking agent, wherein the (F) antistatic agent has a melting point of 25 to 80 represented by the following formula (1) It is an ionic compound at ° C,

K ⁺ A ^- (1)

[In Formula (1), K ⁺ is a cation, and A ^- is one type of anion selected from the group consisting of trifluoromethanesulfonate anion and pentafluoroethanesulfonate anion not containing an imide group]

The acrylic polymer is an acrylic polymer having a glass transition point temperature of 0 ° C or less, and the ionic compound is contained as an essential component in a ratio of 0.01 to 10 parts by weight based on 100 parts by weight of the acrylic polymer. to provide.

The acrylic polymer is (A) at least one or more copolymerizable vinyl monomers containing a hydroxyl group (B-1) with respect to a total of 100 parts by weight of at least one or more (meth)acrylic acid ester monomers having C1 to 18 carbon atoms in an alkyl group. 0.01 to 10 parts by weight in total, and/or (B-2) an acrylic polymer of a copolymer obtained by copolymerizing the total of at least one copolymerizable vinyl monomer containing a carboxyl group in a ratio of 0.01 to 0.5 parts by weight, A) Among 100 parts by weight of at least one C1-C18 (meth)acrylic acid ester monomer in an alkyl group in total, isooctyl (meth)acrylate, isononyl (meth)acrylate, 2-ethylhexyl (meth)acryl 50 parts by weight or more of at least one selected from the group consisting of the above-mentioned acrylic polymer, and 0.1 to 10 parts by weight of a trifunctional or higher-functional isocyanate compound as the (C) crosslinking agent with respect to 100 parts by weight of the acrylic polymer. It is preferable that the pressure-sensitive adhesive composition further contains (D) a crosslinking accelerator for a metal chelate compound and (E) a ketoenol tautomer compound.

The surface resistivity of the pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition is 1.0 × 10 ⁺ 12 Ω / □ or less, and the surface of the PMMA substrate or the TAC substrate of the pressure-sensitive adhesive layer is formed using a resin composition for forming a low refractive index layer containing a fluorine compound. The peeling electrification voltage for the low refractive index layer and the peeling electrification voltage for the plane layer on which the surface of the PMMA substrate or the TAC substrate is not treated are both ±0.3 kV or less, and the pressure-sensitive adhesive layer laminates the protective layer on the polarizer After attaching to an adherend, the surface of the protective layer being a polarizing plate treated with a low-reflection surface treatment with a composition containing a fluorine compound, the temperature was 60 ° C., and the humidity was 90% RH. The stain resistance performance is "no contamination" to the surface of the adherend, and the adhesive force of the pressure-sensitive adhesive layer to the low refractive index layer applied to the surface of the PMMA substrate is 0.04 at a low peeling speed of 0.3 m/min. It is -0.2 N/25 mm, and it is preferable that the adhesive force in high-speed peeling speed of 30 m/min is 2.0 N/25 mm or less.

The (B-1) copolymerizable vinyl monomer containing a hydroxyl group is 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2- At least one selected from the group consisting of hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide ego,

The (B-2) copolymerizable vinyl monomer containing a carboxyl group is (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethylphthalic acid, 2-(meth)acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethylmaleic acid , carboxypolycaprolactone mono(meth)acrylate, and 2-(meth)acryloyloxyethyl tetrahydrophthalic acid.

The pressure-sensitive adhesive composition contains 0.001 to 0.5 parts by weight of the crosslinking accelerator of the (D) metal chelate compound and 0.1 to 300 parts by weight of the ketoenol tautomer compound, based on 100 parts by weight of the acrylic polymer. wherein the (D) crosslinking accelerator of the metal chelate compound 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 weight part of (E)/(D) It is preferable that the ratio is 70 to 1000.

In addition, the present invention provides a pressure-sensitive adhesive film characterized in that a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition is laminated on one side of a resin film.

In addition, the present invention provides a surface protection film using the pressure-sensitive adhesive film.

In addition, the present invention provides a surface protection film for a polarizing plate in which the adhesive film is used.

In addition, the present invention provides an optical film having a pressure-sensitive adhesive layer in which a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition is laminated on at least one side of the optical film.

In addition, the present invention provides a pressure-sensitive adhesive film in which antistatic treatment and antifouling treatment are performed on one side of the resin film, on the opposite side to the side on which the pressure-sensitive adhesive layer is formed.

The pressure-sensitive adhesive composition according to the present invention has excellent adhesive performance and excellent anti-peeling antistatic performance without deterioration over time compared to conventional pressure-sensitive adhesive compositions for surface protection films.

In particular, the surface protection film according to the present invention is an antifouling layer containing a fluorine compound, in which an adherend is laminated on the surface of an optical film, or a low refractive index layer formed using a composition for forming a low refractive index layer containing a fluorine compound. , Compared to the surface protection film according to the prior art, it has excellent adhesion performance and excellent peeling antistatic performance without deterioration over time, and has a remarkable effect on coexistence of antistatic performance and stain resistance performance.

That is, the pressure-sensitive adhesive composition according to the present invention and the surface protective film using the same have excellent adhesive performance, do not deteriorate over time, and have excellent anti-peeling antistatic performance, so they have great industrial use value.

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 antistatic agent, and (C) a crosslinking agent, wherein the (F) antistatic agent is an ion having a melting point of 25 to 80°C represented by the following formula (1) is a sex compound,

K ⁺ A ^- (1)

[In Formula (1), K ⁺ is a cation, and A ^- is one type of anion selected from the group consisting of trifluoromethanesulfonate anion and pentafluoroethanesulfonate anion not containing an imide group]

The acrylic polymer is an acrylic polymer having a glass transition point temperature of 0° C. or less, and the ionic compound is contained as an essential component in a proportion of 0.01 to 10 parts by weight based on 100 parts by weight of the acrylic polymer.

The acrylic polymer used in the pressure-sensitive adhesive composition of the present embodiment is a main polymer of the pressure-sensitive adhesive composition and is an acrylic polymer having a glass transition point temperature of 0°C or lower. The acrylic polymer is preferably (A) a copolymer containing, as a main component, a C1-C18 (meth)acrylic acid ester monomer in an alkyl group.

(A) Examples of (meth)acrylic acid ester monomers having C1 to 18 carbon atoms in an alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl ( meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate , nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl ( meth)acrylate, pentadecyl(meth)acrylate, hexadecyl(meth)acrylate, heptadecyl(meth)acrylate, octadecyl(meth)acrylate, cyclopentyl(meth)acrylate, cyclohexyl(meth)acrylate Acrylates etc. are mentioned. The alkyl group of the alkyl (meth)acrylate monomer may be straight-chain, branched or cyclic.

The acrylic polymer used in the pressure-sensitive adhesive composition of the present embodiment is (A) isooctyl (meth) acrylate, isononyl ( At least one selected from the group consisting of meth)acrylate and 2-ethylhexyl (meth)acrylate is preferably contained in an amount of 50 parts by weight or more, more preferably 60 parts by weight or more, and 75 It is especially preferable to contain in a ratio of parts by weight or more.

The acrylic polymer used in the pressure-sensitive adhesive composition of the present embodiment is (B-1) at least one copolymerizable vinyl monomer containing a hydroxyl group, and/or (B-2) at least one copolymerizable vinyl monomer containing a carboxyl group. It is preferable that it is an acryl-type polymer of the copolymer which copolymerized 1 or more types. The acrylic polymer may be copolymerized with at least one of (B-1) a copolymerizable vinyl monomer containing a hydroxyl group and (B-2) a copolymerizable vinyl monomer containing a carboxyl group, or both may be copolymerized.

The acrylic polymer is (A) at least one or more copolymerizable vinyl monomers containing a hydroxyl group (B-1) with respect to a total of 100 parts by weight of at least one or more (meth)acrylic acid ester monomers having C1 to 18 carbon atoms in an alkyl group. It is preferably an acrylic polymer of a copolymer copolymerized at a ratio of 0.01 to 10 parts by weight in total and/or 0.01 to 0.5 parts by weight in the total of at least one copolymerizable vinyl monomer containing a carboxyl group (B-2). .

(B-1) You may copolymerize the monomer which can be copolymerized containing a hydroxyl group to the acrylic polymer used for the adhesive composition of this embodiment. (B-1) As a copolymerizable monomer containing a hydroxyl group, 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2- At least one selected from the group consisting of hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, etc. It is preferable to be more than

(B-1) In the case of copolymerizing a copolymerizable monomer containing a hydroxyl group, (A) with respect to a total of 100 parts by weight of at least one kind of (meth)acrylic acid ester monomer having C1 to 18 carbon atoms in an alkyl group, (B-1) The copolymerizable monomer containing a hydroxyl group is preferably contained in an amount of 0.01 to 10.0 parts by weight, more preferably in an amount of 0.5 to 7.0 parts by weight, particularly preferably in an amount of 1.0 to 6.0 parts by weight. Do.

(B-2) You may copolymerize the monomer which can be copolymerized containing a carboxyl group to the acrylic polymer used for the adhesive composition of this embodiment. (B-2) Examples of copolymerizable monomers containing a carboxyl group include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethylphthalic acid, 2-(meth)acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethylmaleic acid , carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyl tetrahydrophthalic acid, and the like.

(B-2) In the case of copolymerizing a copolymerizable vinyl monomer containing a carboxyl group, (A) 0.01 to 0.5 weight part relative to 100 parts by weight of a total of at least one type of (meth)acrylic acid ester monomer having C1 to 18 carbon atoms in an alkyl group. It is preferably contained in a proportion of parts, more preferably in a proportion of 0.01 to 0.4 parts by weight, and particularly preferably in a proportion of 0.01 to 0.3 parts by weight.

The production method of the acrylic polymer to be contained in the pressure-sensitive adhesive composition according to the present embodiment is not particularly limited, and a known polymerization method such as a solution polymerization method or an emulsion polymerization method can be used as appropriate. As for the weight average molecular weight of the copolymer of an acrylic polymer, 500,000-3 million are mentioned, for example. It is preferable that the acid value of an acryl-type polymer is 0.1-1.0. For this reason, the stain resistance performance can be improved. Here, "acid value" is one of the indexes indicating the content of an acid, and is expressed as the number of milligrams of potassium hydroxide required to neutralize 1 g of a polymer containing a carboxyl group.

The pressure-sensitive adhesive composition according to the present embodiment contains (F) an antistatic agent. The (F) antistatic agent of the present embodiment is an ionic compound having a melting point of 25 to 80°C represented by the following formula (1).

K ⁺ A ^- (1)

[In Formula (1), K ⁺ is a cation, and A ^- is one type of anion selected from the group consisting of trifluoromethanesulfonate anion and pentafluoroethanesulfonate anion not containing an imide group]

The ionic compound is preferably a solid at room temperature. The normal temperature is, for example, a temperature of less than 25°C, and specifically, it is preferably an ionic compound that is solid at 23°C. The pressure-sensitive adhesive composition according to the present embodiment contains the ionic compound as an essential component in a proportion of 0.01 to 10 parts by weight based on 100 parts by weight of the acrylic polymer.

The cation K ⁺ in formula (1) is pyridinium, imidazolium, phosphonium, sulfonium, pyrrolidinium, guanidinium, ammonium, isuronium, thiouronium, piperidinium, pyrazolium, methylium, It is preferably one type of cation selected from the group consisting of morpholinium.

(F) Specific examples of the antistatic agent include, for example, 1-octyl-2-methylpyridinium trifluoromethanesulfonate salt, 1,2,3-trimethylimidazolium pentafluoroethanesulfonate salt, 1-butyl-2,3-dimethylimidazolium trifluoromethanesulfonate salt, 1-hexyl-4-methylpyridinium pentafluoroethanesulfonate salt, 1-octyl-3-methylpyridinium trifluoromethane A sulfonate salt, n-octylpyridinium trifluoromethane sulfonate salt, etc. are mentioned.

The pressure-sensitive adhesive composition according to the present embodiment further contains (C) a trifunctional or higher functional isocyanate compound as a crosslinking agent. Examples of trifunctional or higher functional isocyanate compounds include biuret-modified and isocyanurate-modified diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, and xylylene diisocyanate. A sieve, trimethylolpropane, and an adduct with a trivalent or higher polyol, such as glycerol, etc. are mentioned. (C) The ratio of the trifunctional or higher functional isocyanate compound as a crosslinking agent is, for example, preferably 0.1 to 10 parts by weight, and 0.1 to 6 parts by weight with respect to 100 parts by weight of the acrylic polymer. more preferable

The pressure-sensitive adhesive composition according to the present embodiment may contain (E) a ketoenol tautomer compound. (E) Examples of ketoenol tautomeric compounds include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate, acetylacetone, 2 , β-diketones such as 4-hexanedione and benzoyl acetone. In the pressure-sensitive adhesive composition using a polyisocyanate compound as a crosslinking agent, by blocking the isocyanate group of the crosslinking agent, excessive viscosity increase and gelation of the pressure-sensitive adhesive composition after blending of the crosslinking agent are suppressed, and the pot life of the pressure-sensitive adhesive composition can be extended. (E) The ketoenol tautomeric compound is preferably at least one selected from the group consisting of acetylacetone and ethyl acetoacetate. It is preferable to contain the ketoenol tautomer compound (E) in an amount of 0.1 to 300 parts by weight based on 100 parts by weight of the acrylic polymer.

The pressure-sensitive adhesive composition according to the present embodiment may contain (D) a crosslinking accelerator of a metal chelate compound. (D) The crosslinking accelerator of the metal chelate compound may be a substance that functions as a catalyst for the reaction (crosslinking reaction) of the copolymer and the crosslinking agent when a polyisocyanate compound is used as a crosslinking agent. (D) The crosslinking accelerator of 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 monodentate ligands X bonded to the metal atom M. Specific examples of the metal chelate compound include tris(2,4-pentanedionate)iron(III), iron trisacetylacetonate, titanium trisacetylacetonate, ruthenium trisacetylacetonate, zinc bisacetylacetonate, aluminum tris Acetylacetonate, zirconium tetrakisacetylacetonate, tris(2,4-hexanedionate)iron(III), bis(2,4-hexanedionate)zinc, tris(2,4-hexanedionate)titanium, Tris(2,4-hexanedionate) aluminum, tetrakis(2,4-hexanedionate) zirconium, etc. are mentioned.

(D) The crosslinking accelerator for the metal chelate compound is preferably at least one metal chelate compound selected from the group consisting of an aluminum chelate compound, a titanium chelate compound, and an iron chelate compound. It is preferable to contain 0.001 to 0.5 parts by weight of the crosslinking accelerator of the metal chelate compound (D) with respect to 100 parts by weight of the acrylic polymer.

Since the (E) ketoenol tautomer compound has an effect of inhibiting crosslinking as opposed to the crosslinking accelerator of (D) metal chelate compound, (E) ketoenol tautomer compound and (D) metal chelate compound It is preferable to appropriately set the ratio of the crosslinking accelerator. In order to elongate the pot life of the pressure-sensitive adhesive composition and improve storage stability, the weight part ratio of (E)/(D) is preferably 70 to 1000, more preferably 70 to 700, and 70 to 300 particularly preferred. Here, the weight part ratio of (E)/(D) is the value of the quotient obtained by dividing the weight part of (E) by the weight part of (D).

The pressure-sensitive adhesive composition according to the present embodiment may contain (H) a polyether-modified siloxane compound as an optional component. (H) The polyether-modified siloxane compound is a siloxane compound having a polyether group, and in addition to a normal siloxane unit [-SiR ¹ ₂ -O-], a siloxane unit having a polyether group [-SiR ¹ (R ² O (R ³ O) ) _n R ⁴ )-O-]. Here, R ¹ is one or two or more alkyl or aryl groups, R ² and R ³ are one or two or more alkylene groups, R ⁴ is one or two or more alkyl or acyl groups (terminal groups) indicate Examples of the polyether group include polyoxyalkylene groups such as polyoxyethylene group [(C ₂ H ₄ O) _n ] and polyoxypropylene group [(C ₃ H ₆ O) _n ]. In the siloxane unit having a polyether group, the terminal of the polyether group may be an OH group (R ⁴ =H in the above formula).

(H) The polyether-modified siloxane compound is preferably a polyether-modified siloxane compound having an HLB value of 6 to 12. In addition, with respect to 100 parts by weight of the acrylic polymer, the (H) polyether-modified siloxane compound is preferably contained in an amount of 0.01 to 0.5 parts by weight, more preferably 0.02 to 0.35 parts by weight, and includes 0.02 to 0.25 parts by weight. It is particularly desirable to be The HLB value is a hydrophilic-lipophilic balance (hydrophilic-lipophilic ratio) defined, for example, by JIS K3211 (surfactant term) or the like.

The polyether-modified siloxane compound can be obtained, for example, by grafting an organic compound having an unsaturated bond and a polyoxyalkylene group to a polyorganosiloxane main chain having a silicon hydride group through a hydrosilylation reaction. Specifically, dimethylsiloxane/methyl (polyoxyethylene) siloxane copolymer, dimethylsiloxane/methyl (polyoxyethylene) siloxane/methyl (polyoxypropylene) siloxane copolymer, dimethylsiloxane/methyl (polyoxypropylene) siloxane polymer, etc. can be heard

(H) By blending the polyether-modified siloxane compound into the pressure-sensitive adhesive composition, the adhesive strength and rework performance of the pressure-sensitive adhesive layer can be improved. (H) It is preferable that the weight average molecular weight of a polyether modified siloxane compound is 10000 or less. From the viewpoint of compatibility with acrylic polymers, the lower the HLB value and the lower the molecular weight, the better the compatibility. However, the lower molecular weight polyether-modified siloxane compound has a relatively high HLB value and excellent antistatic properties even if the compatibility with the polymer is slightly low. is obtained

The pressure-sensitive adhesive composition of the present embodiment is not limited to the above-mentioned additives, and known additives such as surfactants, curing accelerators, plasticizers, fillers, curing retardants, processing aids, anti-aging agents, and antioxidants may be suitably blended. These may be used alone or in combination of two or more.

The adhesive composition of this embodiment is suitable as an adhesive composition for surface protection films bonded to the polarizer protective layer of a polarizing plate. Here, one kind selected from the group which the polarizer protective layer of a polarizing plate consists of a TAC-type film, a PMMA-type film, and a PET-type film is mentioned. Here, TAC is an abbreviation for triacetyl cellulose, PMMA for polymethyl methacrylate, and PET for polyethylene terephthalate.

In addition, the surface treatment applied to the surface of the polarizer protective layer of the polarizing plate may be one selected from the group consisting of untreated, AG treatment, LR treatment, AR treatment, AG-LR treatment, and AG-AR treatment. Here, AG is anti-glare, LR is low reflection, and AR is anti-reflection.

The surface resistivity of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition of the present embodiment is preferably 1.0×10 ⁺¹² Ω/□ or less, more preferably 5.0×10 ⁺¹¹ Ω/□ or less, and 1.0×10 ⁺¹¹ Ω/□ or less. It is especially preferable that it is below. When the surface resistivity is large, the ability to escape static electricity generated when peeling the pressure-sensitive adhesive layer from the adherend is poor. For this reason, by making the surface resistivity sufficiently small, the peeling electrification voltage generated accompanying static electricity generated when peeling the pressure-sensitive adhesive layer from the adherend is reduced, and it is possible to suppress the influence on the adherend.

The pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition of the present embodiment has a peeling electrification voltage of ±0.3 kV or less, that is, -0.3 to -0.3 kV, relative to the low-refractive-index layer formed using the resin composition for forming a low-refractive-index layer containing a fluorine compound. It is preferable to be within the range of +0.3 kV. As the fluorine compound used in the composition for forming the low refractive index layer, a fluorine-containing copolymer that is a polymer of one or more kinds of fluorinated olefins, fluorinated vinyl ethers, fluorinated alkyl (meth)acrylates, etc., and silane compounds containing a fluorinated alkyl group. Condensates, such as these, are mentioned. In the fluorinated copolymer, fluorinated monomers as well as non-fluorinated monomers such as olefins, vinyl ethers, and (meth)acrylates may be copolymerized. The low refractive index layer may constitute an antireflection layer in combination with a high refractive index layer or the like.

When measuring the peeling electrification voltage for the low refractive index layer, examples of the substrate for forming the low refractive index layer on the surface include a PMMA substrate and a TAC substrate. In addition, the pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition of the present embodiment has a peeling electrification voltage of ±0.3 kV or less, that is, -0.3 to +0.3 kV, with respect to a plane layer in which the surface of the PMMA substrate or the TAC substrate is not subjected to any treatment. It is preferable that it is within the range of

After the adhesive layer is bonded to the adherend, it is left for 48 hr in an atmosphere of a temperature of 60 ° C. and a humidity of 90% RH, and the contamination resistance performance after 1 day of removal from the atmosphere is "no stain" on the surface of the adherend. desirable. Examples of the adherend include a polarizing plate in which a protective layer is laminated on a polarizer and the surface of the protective layer is treated with a low-reflection surface treatment with a composition containing a fluorine compound. The composition containing the fluorine compound used for the low-reflection surface treatment may be the same as or different from the above-mentioned resin composition for forming a low refractive index layer containing the fluorine compound. Examples of the protective layer include a PMMA substrate and a TAC substrate.

The adhesive strength of the pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition of the present embodiment to the low refractive index layer applied to the surface of the PMMA substrate is 0.04 to 0.2 N/25 mm at a low peeling rate of 0.3 m/min, and a high speed peeling rate of 0.3 m/min. It is preferable that the adhesive force at a peeling rate of 30 m/min is 2.0 N/25 mm or less, and it is more preferable that the adhesive force at a high-speed peeling rate of 30 m/min is 0.2 to 1.6 N/25 mm. For this reason, performance with little change in adhesive force is obtained even with the peeling speed, and it becomes possible to peel rapidly also by high-speed peeling. In addition, even when once peeling off the surface protection film for re-adhesion, excessive force is not required and it is easy to peel from the adherend.

It is preferable that it is 95 to 100%, and, as for the gel fraction of the adhesive layer formed by crosslinking the adhesive composition of this embodiment, it is more preferable that it is 97 to 100%. In this way, the high gel fraction of the pressure-sensitive adhesive layer does not increase the adhesive strength at a low peeling rate, reduces the elution of unpolymerized monomers or oligomers from the copolymer, and improves reworkability and durability at high temperatures and high humidity. and contamination of the adherend can be suppressed.

The adhesive film of this embodiment forms the adhesive layer formed by crosslinking the adhesive composition of this embodiment on one side or both surfaces of a resin film. Moreover, the surface protection film of this embodiment is a surface protection film formed by forming the adhesive layer formed by crosslinking the adhesive composition of this embodiment on one surface of a resin film. The pressure-sensitive adhesive composition of the present embodiment has excellent antistatic performance, excellent balance of adhesive strength at low peeling rates and high-speed peeling rates, and also has stain resistance. For this reason, it can use suitably for the use of the surface protection film of a polarizing plate.

Resin films, such as a polyester film, etc. can be used as the base film of an adhesive layer, or a release film (separator) which protects an adhesive surface.

Antistatic treatment and antifouling treatment may be applied to the surface opposite to the side on which the pressure-sensitive adhesive layer is formed on one side of the resin film. As an antistatic treatment, application|coating or mixing of an antistatic agent, etc. are mentioned. As the antifouling treatment, treatment with a silicone-based or fluorine-based mold release agent or coating agent, silica fine particles, or the like is exemplified. In the release film, a release treatment may be given to the surface on the side aligned with the adhesive surface of the pressure-sensitive adhesive layer with a release agent such as silicone, fluorine, or long-chain alkyl.

Moreover, the optical film with an adhesive layer can be obtained by laminating|stacking the adhesive layer which crosslinked the adhesive composition of this embodiment on at least one surface of an optical film. Examples of the optical film include a polarizing film, a retardation film, an antireflection film, an antiglare (antiglare) film, an ultraviolet absorbing film, an infrared absorbing film, an optical compensation film, and a brightness enhancing film. As a device to which an optical member is applied, a liquid crystal panel, an organic EL panel, a touch panel, etc. are mentioned.

In the case of surface protection films for optics, such as surface protection films for polarizing plates, and adhesive films, it is preferable that the base film and the adhesive layer have sufficient transparency.

Example

Hereinafter, the present invention will be described in detail by way of examples.

<Manufacture of acrylic polymer>

[Example 1]

Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube, and the air in the reaction apparatus was substituted with nitrogen gas. Then, the solvent (ethyl acetate) was added to the reaction apparatus with 100 weight part of 2-ethylhexyl acrylate, 6.0 weight part of 8-hydroxyoctyl acrylate, and 0.1 weight part of acrylic acid. Thereafter, 0.1 part by weight of azobisisobutyronitrile was added dropwise over 2 hours as a polymerization initiator and reacted at 65°C for 6 hours to obtain an acrylic polymer used in Example 1.

[Examples 2 to 6 and Comparative Examples 1 to 3]

Examples 2 to 6 in the same manner as the acrylic polymer solution used in Example 1, except that the composition of the monomers was the same as those described in Table 1 (A), (B-1), and (B-2), respectively. and acrylic polymer solutions used in Comparative Examples 1 to 3 were obtained.

<Manufacture of adhesive composition and surface protection film>

[Example 1]

With respect to the acrylic polymer solution of Example 1 prepared as described above, 2.5 parts by weight of a crosslinking agent (Coronate HX), 1.5 parts by weight of an antistatic agent (1-octyl-2-methylpyridinium trifluoromethanesulfonate salt), crosslinking agent A catalyst (titanium trisacetylacetonate) 0.1 weight part and acetylacetone 8.5 weight part were added and stirred and mixed, and the adhesive composition of Example 1 was obtained. After apply|coating this adhesive composition on a release film (PET film coated with silicone resin), the solvent was removed by drying at 90 degreeC, and the adhesive layer with a thickness of 20 micrometers was obtained. After that, the pressure-sensitive adhesive layer having the release film formed on the surface opposite to the antistatic and antifouling-treated surface of the base film (PET film treated with antistatic and antifouling on one side) is transferred, and "substrate film/adhesive layer/ A surface protection film of Example 1 having a laminated structure of "release film" was obtained.

[Examples 2 to 6 and Comparative Examples 1 to 3]

The surface protection films of Examples 2 to 6 and Comparative Examples 1 to 3 were prepared in the same manner as the surface protection film of Example 1 except that the composition of the additives was set as described in (C) to (F) of Table 1, respectively. got it

In Table 1, the weight part of (B-1) and (B-2) was calculated|required by taking the total of C1-C18 (meth)acrylic acid ester monomers of (A) alkyl group as 100 weight part.

Here, in Table 1, in each column (C) to (F), the acrylic polymer was 100 parts by weight, and the content ratio (parts by weight) of each component was shown in parentheses (　).

In addition, Table 2 shows the compound name of the abbreviation of each component used in Table 1. Here, 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 Corporation.

(F) Among the antistatic agents, F-1 to F-6 and F-9 are ionic compounds that have a melting point of 25°C or more and 80°C or less and are solid at room temperature. F-7 and F-8 are ionic compounds with melting points greater than 80°C and solids at room temperature.

<Test method and evaluation>

After aging the surface protection films in Examples 1 to 6 and Comparative Examples 1 to 3 for 7 days in an atmosphere of a temperature of 23°C and a humidity of 50% RH, respectively, the following test methods were evaluated.

<Method for testing adhesion>

The surface protection film in which the release film was peeled off to expose the pressure-sensitive adhesive layer was bonded to the surface of the polarizing plate through the pressure-sensitive adhesive layer, and left to stand for 1 day, followed by an autoclave treatment at 50 ° C. What was allowed to stand for a period of time was used as a measurement sample for adhesive strength. The peel strength measured by peeling the obtained measurement sample in the 180° direction at a low speed (0.3 m/min) or high speed (30 m/min) using a tensile tester was taken as adhesive strength.

Here, the polarizer protective layer of the polarizing plate is one selected from the group consisting of triacetyl cellulose (TAC), polymethyl methacrylate (PMMA), and polyethylene terephthalate (PET).

In addition, in the LR polarizing plate and the AG-LR polarizing plate, the surface of the polarizer protective layer of the polarizing plate is subjected to low-reflection surface treatment with a composition containing a fluorine compound.

<Test method for surface resistivity>

After aging the surface protection film, before attaching to the polarizing plate, the release film is peeled off to expose the pressure-sensitive adhesive layer, and the surface resistivity of the pressure-sensitive adhesive layer is measured using a resistivity meter Hirestar UP-HT450 (manufactured by Mitsubishi Chemical Analyst) did.

<Test method for peeling electrification voltage>

The surface protection film in which the release film was peeled off to expose the pressure-sensitive adhesive layer was bonded to a polarizing plate having a low refractive index layer formed on the adhered surface using a composition for forming a low refractive index layer containing a fluorine compound. When the surface protective film was peeled at 180° at a tensile speed of 30 m/min, the voltage (electrical voltage) generated by charging the adherend was measured using high-precision electrostatic sensors SK-035 and SK-200 (manufactured by Keyence Corporation). , the maximum value of the measured value was taken as the peeling electrification voltage.

<Test method for antifouling performance>

A polarizing plate subjected to low-reflection (LR) surface treatment on one side of the glass plate was bonded through an adhesive layer (double-sided adhesive tape) using a bonding machine. After that, a surface protection film was bonded to the surface of the polarizing plate using a bonding machine. After bonding to the adherend, it was left to stand for 48 hr in an atmosphere of a temperature of 60°C and a humidity of 90% RH, and the surface protection film was peeled off 1 day after taking out from the atmosphere, and the contamination state on the surface of the polarizing plate was visually observed. The criterion for the stain resistance performance was evaluated as "○" for no stain on the surface of the polarizing plate, "Δ" for slightly stain, and "×" for stain.

In Table 3, the evaluation results about the surface protection films in Examples 1-6 and Comparative Examples 1-3 are shown. "Surface resistivity" was expressed by a method in which "m × 10 ^{+ n} " was expressed as "mE + n" (however, m is an arbitrary real value and n is a positive integer).

The column of "peeling electrification voltage" indicates the material (TAC or PMMA) and surface treatment (Plain or AG-LR) of the polarizer protective layer of the polarizing plate used in the test. Plain of "surface treatment" means untreated. In the same manner as in the column of "stain resistance performance", the material (PMMA) and surface treatment (AG-LR) of the polarizer protective layer of the polarizing plate used in the test were shown.

The surface protection films of Examples 1 to 6 had an adhesive force of 0.04 to 0.2 N/25 mm at a low peel rate of 0.3 m/min to a polarizing plate as an adherend, and an adhesive force of 2.0 N/25 mm at a high peel rate of 30 m/min. Below, the adhesion performance was excellent.

In addition, the surface protection films of Examples 1 to 6 have a surface resistivity of the pressure-sensitive adhesive layer of 1.0 × 10 ⁺ 12 Ω / □ or less, and a low-refractive-index layer formed using a composition for forming a low-refractive-index layer containing a fluorine compound. The peeling electrification voltage of the layer was within the range of -0.3 to +0.3 kV, and the antistatic performance was excellent.

In addition, the surface protection films of Examples 1 to 6 have peeling electrification voltages of the pressure-sensitive adhesive layer in the range of -0.3 to +0.3 kV, even for untreated PMMA substrates and TAC substrates without a low refractive index layer, and antistatic performance this was excellent

Furthermore, after attaching the surface protection films of Examples 1 to 6 to an adherend, they were left for 48 hr in an atmosphere of a temperature of 60 ° C. and a humidity of 90% RH, and a polarizing plate subjected to low-reflection surface treatment as an adherend even after 1 day after being taken out from the atmosphere. There was no contamination, and the contamination resistance performance was also excellent.

That is, the evaluation results shown in Table 3 for the surface protection films of Examples 1 to 6 demonstrated that the problems of the present invention could be solved.

The surface protection film of Comparative Example 1 contains an antistatic agent having a melting point of more than 80°C. For this reason, the surface protection film of Comparative Example 1 had a high adhesive force of the pressure-sensitive adhesive layer, a high peeling electrification voltage, and poor stain resistance.

In addition, the surface protection film of Comparative Example 2 contains an antistatic agent having a melting point of more than 80°C. For this reason, the surface protection film of Comparative Example 2 had a high adhesive force of the pressure-sensitive adhesive layer, a high peeling electrification voltage, and poor stain resistance.

In addition, the surface protection film of Comparative Example 3 has a melting point of 25 to 80°C, but contains an antistatic agent in which an anion has an imide group. For this reason, the surface protection film of Comparative Example 3 had a high peeling electrification voltage with respect to the PMMA substrate, and was also poor in stain resistance.

Thus, the subject of this invention could not be solved with the surface protection films of Comparative Examples 1-3.

Claims (3)

An adhesive film in which an adhesive layer obtained by crosslinking an acrylic polymer and an adhesive composition containing (F) an antistatic agent is laminated on at least one surface of a resin film,
The (F) antistatic agent is an ionic compound that is a solid at a temperature of 23 ° C. and has a melting point of 25 to 80 ° C. represented by the following formula (1):
K ⁺ A ^- (1)
[In Formula (1), K ⁺ is a cation, and A ^- is one type of anion selected from the group consisting of trifluoromethanesulfonate anion and pentafluoroethanesulfonate anion not containing an imide group]. A surface protection film using the adhesive film of claim 1. According to claim 1,
An adhesive film in which the resin film is an optical film.