KR20160150093A - Adhesive composition and surface protection film - Google Patents

Abstract

The present invention provides a pressure-sensitive adhesive composition and a surface protective film which are excellent in antistatic performance, excellent in balance of adhesive force at low speed peeling speed and high-speed peeling speed, and also excellent in endurance performance and rework performance. (A) a (meth) acrylic acid ester monomer having an alkyl group of C4 to C18, (B) a copolymerizable monomer containing a hydroxyl group, (C) a copolymerizable monomer containing a carboxyl group, and (D) a polyalkylene glycol (Meth) acrylate monomer, and (E) a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkyl (meth) acrylate monomer containing an alkoxy group. (F) a trifunctional or higher isocyanate compound, (G) a bifunctional aliphatic isocyanate compound, and (H) an antistatic agent.

Description

ADHESIVE COMPOSITION AND SURFACE PROTECTION FILM < RTI ID = 0.0 >

The present invention relates to a surface protective film used in a manufacturing process of a liquid crystal display. More specifically, the present invention relates to a pressure-sensitive adhesive composition for a surface protective film, which is used for protecting the surface of optical members such as a polarizing plate and a retarder by attaching (sticking) the surface of an optical member such as a polarizing plate, And a surface protective film using the same.

BACKGROUND ART [0002] Conventionally, in a manufacturing process of an optical member such as a polarizing plate and a retarder, which constitute a liquid crystal display, a surface protective film for temporarily protecting the surface of an optical member is attached. Such a surface protective film is used only for the process of manufacturing the optical member, and is peeled off from the optical member at the time of mounting the optical member on the liquid crystal display. Since the surface protective film for protecting the surface of such an optical member is used only in the manufacturing process, it is sometimes called a process film in general.

In the surface protective film used in the step of manufacturing the optical member, the pressure-sensitive adhesive layer is formed on one side of the polyethylene terephthalate (PET) resin film having optical transparency. However, when the adhesive is applied to the optical member , A release film peeled off to protect the pressure-sensitive adhesive layer is bonded onto the pressure-sensitive adhesive layer.

Since optical members such as a polarizing plate and a retardation plate are subjected to a product inspection accompanied by optical evaluation such as display ability, color, contrast, and foreign matter incorporation of the liquid crystal display plate in a state where the surface protective film is stuck, It is required that the pressure-sensitive adhesive layer is free of bubbles or foreign matter.

In recent years, when peeling the surface protective film from optical members such as a polarizing plate and a retardation plate, peeling electrification caused by static electricity generated when the adherend is peeled off affects the failure of the electric control circuit of the liquid crystal display And there is a demand for an excellent antistatic property for the pressure-sensitive adhesive layer.

When the surface protective film is attached to an optical member such as a polarizing plate or a phase difference plate, there is a case where the surface protective film is peeled once and then the surface protective film is attached again for various reasons. At this time, It is required to easily peel off (reworkability).

In addition, when the surface protective film is finally peeled off from optical members such as a polarizing plate and a phase difference plate, it is required to be able to peel quickly. It is required that the adhesive force is small even by the peeling speed so that it can be quickly peeled off by the so-called high-speed peeling.

Thus, in recent years, the required performance of the pressure-sensitive adhesive layer constituting the surface protective film has been improved by (1) balancing the adhesive force at the low-speed peeling speed and the high-speed peeling speed, (2) (3) excellent antistatic performance, and (4) reworkability and the like are demanded from the ease of use in the use of the surface protective film.

(1) to (4) required for the pressure-sensitive adhesive layer constituting the surface-protective film can satisfy the respective required performance, 4) It was a very difficult task to satisfy all required performance simultaneously.

For example, the following proposals are known for (1) balancing the adhesive force at a low speed peeling speed and a high speed peeling speed, and (2) preventing the occurrence of adhesive residue.

In the acrylic pressure-sensitive adhesive layer comprising a copolymer of a (meth) acrylic acid alkyl ester having an alkyl group having 7 or less carbon atoms and a carboxyl group-containing copolymerizable compound as a main component and crosslinking the same with a crosslinking agent, the pressure- And there is also a problem that the adhesiveness to the adherend increases with time.

In order to avoid this, it has been known to use 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 to form a pressure-sensitive adhesive layer crosslinked with a crosslinking agent Patent Document 1).

It has also been proposed that a small amount of a copolymer of a (meth) acrylic acid alkyl ester and a carboxyl group-containing copolymerizable compound is added to the same copolymer as described above, and a pressure-sensitive adhesive layer is formed by crosslinking the copolymer with a crosslinking agent. However, when they are used for protecting the surface of a plastic plate or the like having a low surface tension due to low surface tension, there arises a problem of peeling phenomenon such as lifting due to heating during processing or storage, There was also a problem that the peelability was poor.

In order to solve these problems, it is preferable that (a) 100 parts by weight of (a) a (meth) acrylic acid alkyl ester having a (meth) acrylic acid alkyl ester having an alkyl group having 8 to 10 carbon atoms as a main component, And c) 3 to 100 parts by weight of a vinyl ester of an aliphatic carboxylic acid having 1 to 5 carbon atoms is added to a copolymer of a monomer mixture containing a crosslinking agent in an equivalent amount or more with respect to the carboxyl group of the component b) (Patent Document 2).

In the pressure-sensitive adhesive composition described in Patent Document 2, peeling phenomenon such as peeling is not generated during processing or storage, and the peeling property of the adhesive force is small with time, It is possible to re-peel off with a small force even when stored for a long period of time, and it is possible to re-peel off with a small force even when high-speed peeling is performed without generating adhesive residue on the adherend.

As for the excellent antistatic performance, (3) a method of incorporating an antistatic agent into a base film as a method for imparting antistatic property to the surface protective film is disclosed. Examples of the antistatic agent include (a) various cationic antistatic agents having cationic groups such as quaternary ammonium salts, pyridinium salts and primary to tertiary amino groups, (b) sulfonic acid bases, sulfuric acid ester bases, phosphoric acid An anionic antistatic agent having an anionic group such as an ester base or a phosphonic acid base, (c) a positive antistatic agent such as amino acid or amino sulfate ester, (d) a nonionic antioxidant such as amino alcohol, glycerin or polyethylene glycol (E) a polymer-type antistatic agent obtained by polymerizing an antistatic agent as described above (Patent Document 3).

Further, in recent years, it has been proposed to incorporate such an antistatic agent directly in the pressure-sensitive adhesive layer, either in the base film or not in the surface of the base film.

Regarding the (4) rework performance, for example, a pressure-sensitive adhesive composition in which a curing agent of an isocyanate compound and a specific silicate oligomer are incorporated in an acrylic resin in an amount of 0.0001 to 10 parts by weight based on 100 parts by weight of an acrylic resin (Patent Document 4).

Patent Document 4 discloses a method for producing a polyester resin composition which comprises an acrylic acid alkyl ester having an alkyl group of about 2 to 12 carbon atoms or a methacrylic acid alkyl ester having an alkyl group of about 4 to 12 as a main monomer component, Containing functional monomer component and a functional group-containing monomer component. The content of the monomer component containing a functional group is preferably 0.001 to 50% by weight, more preferably 0.001 to 25% by weight, still more preferably 0.01 to 25% by weight, . The pressure-sensitive adhesive composition described in Patent Document 4 is said to exhibit reworkability because it exhibits a small change in cohesive force and adhesive force over time under high temperature or high temperature and high humidity, and also exhibits an excellent adhesive force against a curved surface.

Generally, if the pressure-sensitive adhesive layer has a soft property, the pressure-sensitive adhesive residue tends to be generated, and the workability tends to decrease. In other words, it is difficult to re-peel off when it is mistakenly bonded, and it is apt to be difficult to re-peel off. Therefore, it is considered that it is necessary to cross-link a monomer having a functional group such as a carboxyl group to a main agent so as to make the pressure-sensitive adhesive layer have a constant hardness, in order to make it work-free.

Japanese Patent Application Laid-Open No. 63-225677 Japanese Laid-Open Patent Publication No. 11-256111 Japanese Laid-Open Patent Publication No. 11-070629 Japanese Unexamined Patent Publication No. 8-199130

In the prior art, there has been a demand for a balance of adhesive force at a low speed peeling speed and a high speed peeling speed, an excellent antistatic performance and a rework performance as required performance of a pressure-sensitive adhesive layer constituting a surface protective film. However, even if each of the required performance can be satisfied, all the required performance required for the pressure-sensitive adhesive layer of the surface protective film could not be satisfied.

The present invention has been made in view of the above circumstances and has an object to provide a pressure-sensitive adhesive composition and surface protection which have an excellent antistatic property and are excellent in balance of adhesive force at a low speed release speed and a high speed release speed, To provide a film.

(A) a monomer copolymerizable with at least one of (meth) acrylic acid ester monomers having an alkyl group having from 4 to 18 carbon atoms, (B) a copolymerizable monomer containing a hydroxyl group, (C) a carboxyl group-containing copolymerizable monomer, (D) a polyalkylene glycol mono (meth) acrylate monomer, and (E) a nitrogen-containing vinyl monomer or alkoxy group-containing alkyl (F) a trifunctional or higher isocyanate compound, (G) a bifunctional aliphatic aliphatic isocyanate compound, (H) a polyfunctional alicyclic isocyanate compound, and Sensitive adhesive composition according to the present invention.

When the total amount of the acrylic polymer of the copolymer is 100 parts by weight,

(A) 50 to 91 parts by weight of a (meth) acrylic acid ester monomer having an alkyl group having 4 to 18 carbon atoms,

0.1 to 10 parts by weight of the copolymerizable monomer containing the hydroxyl group (B)

0 to 1.0 part by weight of the copolymerizable monomer containing the carboxyl group (C)

0 to 50 parts by weight of (D) the polyalkylene glycol mono (meth) acrylate monomer,

It is preferable that the (E) nitrogen-containing vinyl monomer containing no hydroxyl group or the alkyl (meth) acrylate monomer containing an alkoxy group is contained in an amount of 0 to 20 parts by weight.

The weight ratio (F / G) of the (F) trifunctional or higher isocyanate compound to the (G) bifunctional alicyclic isocyanate compound is 1 to 90, It is preferable that the total amount of the isocyanate compound having a higher functional group and the (G) difunctional aliphatic isocyanate compound is 0.1 to 5.0 parts by weight.

The bifunctional aliphatic isocyanate compound (G) is a compound produced by reacting a diisocyanate compound with a diol compound. As the diisocyanate compound, it is preferable that the aliphatic diisocyanate is one selected from the group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate. Examples of the diol compound include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxypivalate, polyethylene glycol and polypropylene glycol And the like.

Further, the copolymerizable monomer (B) containing a hydroxyl group is preferably selected from the group consisting of 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl At least one compound selected from the group consisting of N-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide and N-hydroxyethyl desirable.

The copolymerizable monomer containing (C) a carboxyl group is preferably selected from the group consisting of (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethylhexahydrophthalic acid, (Meth) acryloyloxyethyl methacrylate, 2- (meth) acryloyloxyethyl methacrylate, 2- (meth) acryloyloxyethyl methacrylate, 2- At least one member selected from the group consisting of carboxypolycaprolactone mono (meth) acrylate and 2- (meth) acryloyloxyethyltetrahydrophthalic acid is preferable.

Also, when the polyalkylene glycol mono (meth) acrylate monomer (D) is a polyalkylene glycol mono (meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, ethoxypolyalkylene glycol Acrylate, and the like.

Wherein the isocyanurate compound of the hexamethylene diisocyanate compound, the isocyanurate compound of the isophorone diisocyanate compound, the adduct of the hexamethylene diisocyanate compound, the isocyanurate compound of the isophorone diisocyanate compound, An isocyanurate compound of a xylylene diisocyanate compound, a hydrogenated xylylene diisocyanate compound, an isocyanurate compound of a xylylene diisocyanate compound, an isocyanurate compound of a xylylene diisocyanate compound, a xylylene diisocyanate compound, At least one selected from the group consisting of an isocyanurate of a compound, an adduct of a tolylene diisocyanate compound, an adduct of a xylylene diisocyanate compound, and an adduct of a hydrogenated xylylene diisocyanate compound desirable.

It is preferable that the acryl-based polymer includes at least one or more of nitrogen-containing vinyl monomers or alkoxy group-containing alkyl (meth) acrylate monomers (E) that do not contain a hydroxyl group as the copolymerizable monomer group.

The antistatic agent (H) is contained in an amount of 0.01 to 5.0 parts by weight based on 100 parts by weight of the copolymer and has a melting point of 30 to 50 DEG C, or 0.1 to 5.0% It is preferably an ionic compound containing a copolymerized acryloyl group.

The pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition preferably has an adhesive force of 0.05 to 0.1 N / 25 mm at a low speed peeling rate of 0.3 m / min and an adhesive force of 1.0 N / 25 mm or less at a high peeling rate of 30 m / Do.

It is also preferable that the pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition has a surface resistivity of 5.0 x 10 ⁺ 10? /? Or less and a peeling electrification voltage of 占 0 to 1 kV.

The present invention also provides a surface protective film comprising a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition on one side or both sides of a resin film.

Further, the surface protective film of the present invention can be used as a surface protective film of a polarizing plate.

It is preferable that the surface protective film of the present invention is subjected to antistatic treatment and antifouling treatment on the side of the resin film opposite to the side where the pressure-sensitive adhesive layer is formed.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to satisfy all the performance required for the pressure-sensitive adhesive layer of the surface protective film, which can not be solved by the prior art, and to obtain excellent antistatic performance and to prevent the occurrence of adhesive residue. Specifically, the addition amount of the antistatic agent can be reduced while maintaining an excellent antistatic property, and the performance of preventing the occurrence of adhesive residue can be further improved.

Further, by using the (G) bifunctional aliphatic isocyanate compound (F) in combination with the trifunctional or higher functional isocyanate compound, the crosslinking property is excellent and the stain resistance is improved. Further, Excellent balance.

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 comprising a copolymerizable monomer containing a hydroxyl group (B) as a monomer copolymerizable with at least one of (A) a (meth) acrylic acid ester monomer having an alkyl group of C4- (C) a carboxyl group-containing copolymerizable monomer, (D) a polyalkylene glycol mono (meth) acrylate monomer, and (E) a nitrogen-containing vinyl monomer or alkoxy group-containing alkyl (F) a trifunctional or higher isocyanate compound, (G) a bifunctional aliphatic aliphatic isocyanate compound, (H) a polyfunctional alicyclic isocyanate compound, and And further contains an inhibitor.

(A) from 50 to 91 parts by weight of a (meth) acrylic acid ester monomer having an alkyl group having from 4 to 18 carbon atoms, wherein the total amount of the acrylic polymer in the copolymer is 100 parts by weight, 0.1 to 10 parts by weight of a copolymerizable monomer, 0 to 1.0 part by weight of a copolymerizable monomer containing the carboxyl group (C), 0 to 50 parts by weight of the polyalkylene glycol mono (meth) acrylate monomer (D) It is preferable that the (E) nitrogen-containing vinyl monomer containing no hydroxyl group or the alkyl (meth) acrylate monomer containing an alkoxy group is contained in an amount of 0 to 20 parts by weight.

Examples of the (meth) acrylic acid ester monomer (A) in which the alkyl group has 4 to 18 carbon atoms include butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (Meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (Meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (Meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, myristyl (meth) acrylate, isomyristyl Cetyl (meth) acrylate Sites, and the like can be mentioned stearyl (meth) acrylate, isostearyl (meth) acrylate.

It is preferable that (A) the (meth) acrylic acid ester monomer having an alkyl group of C4 to C18 is contained in an amount of 50 to 91 parts by weight, when the total amount of the acrylic polymer of the copolymer is 100 parts by weight.

Examples of the copolymerizable monomer containing a hydroxyl group (B) include a copolymerizable monomer having a hydroxyl group such as 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) (Meth) acrylate such as ethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (Meth) acrylamides containing hydroxyl groups.

(Meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy ) Acrylamide, N-hydroxymethyl (meth) acrylamide and N-hydroxyethyl (meth) acrylamide.

When the total amount of the acrylic polymer of the copolymer is 100 parts by weight, it is preferable that the copolymerizable monomer containing the hydroxyl group (B) is contained in a proportion of 0.1 to 10 parts by weight.

(Meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethylhexahydrophthalic acid, 2- (Meth) acryloyloxyethylmaleic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxyethylsuccinic acid, 2- Caprolactone mono (meth) acrylate, 2- (meth) acryloyloxyethyltetrahydrophthalic acid, and the like.

When the total amount of the acrylic polymer of the copolymer is 100 parts by weight, it is preferable that the copolymerizable monomer containing the carboxyl group (C) is contained at a ratio of 0 to 1.0 part by weight. In the pressure-sensitive adhesive layer according to the present invention, a copolymerizable monomer containing a carboxyl group (C) may not be contained in the pressure-sensitive adhesive composition.

As the (D) polyalkylene glycol mono (meth) acrylic acid ester monomer, any of the plurality of hydroxyl groups of the polyalkylene glycol may be a compound in which one hydroxyl group is esterified as a (meth) acrylic acid ester. (Meth) acrylic acid ester group becomes a polymerizable group, it can be copolymerized with the subject polymer. The other hydroxyl group may be the same as OH, or may be an alkyl ether such as methyl ether or ethyl ether, or a saturated carboxylic acid ester such as acetic acid ester.

Examples of the alkylene group of the polyalkylene glycol include an ethylene group, a propylene group, and a butylene group, but are not limited thereto. 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, and polyethylene glycol-polypropylene glycol-polybutylene glycol. The copolymer may be a block copolymer or a random copolymer.

(D) the average number of repeats of the alkylene oxide constituting the polyalkylene glycol chain of the polyalkylene glycol mono (meth) acrylic acid ester monomer is preferably 3 to 14. [ The "average number of repeating units of alkylene oxide" refers to the number of repeating units in the "polyalkylene glycol chain" included in the molecular structure of the polyalkylene glycol mono (meth) acrylate monomer (D) It is the average number.

Examples of the polyalkylene glycol mono (meth) acrylate monomer (D) include polyalkylene glycol mono (meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, ethoxypolyalkylene glycol (meth) And at least one selected from the group consisting of:

More specifically, there may be mentioned polyolefin such as polyethylene glycol-mono (meth) acrylate, polypropylene glycol-mono (meth) acrylate, polybutylene glycol- mono (meth) acrylate, polyethylene glycol-polypropylene glycol- Poly (ethylene glycol) -polybutylene glycol-mono (meth) acrylate, polypropylene glycol-polybutylene glycol-mono (meth) acrylate, polyethylene glycol-polypropylene glycol- Rate; Methoxypolyethylene glycol- (meth) acrylate, methoxypolyethylene glycol- (meth) acrylate, methoxypolypropylene glycol- (meth) acrylate, methoxypolybutylene glycol- (meth) acrylate, methoxypolyethylene glycol- (Meth) acrylate, methoxy-polyethylene glycol-polybutylene glycol- (meth) acrylate, methoxypolypropylene glycol-polybutylene glycol- (meth) acrylate, methoxy-polyethylene glycol-polypropylene glycol-polybutylene Glycol - (meth) acrylate; Acrylate, ethoxypolyethylene glycol- (meth) acrylate, ethoxypolyethylene glycol- (meth) acrylate, ethoxypolypropylene glycol- (meth) acrylate, ethoxypolybutylene glycol- (Meth) acrylate, ethoxy-polyethylene glycol-polybutylene glycol- (meth) acrylate, ethoxy-polypropylene glycol-polybutylene glycol- Glycol- (meth) acrylate, and the like.

It is preferable that the polyalkylene glycol mono (meth) acrylate monomer (D) is contained in an amount of 0 to 50 parts by weight, based on 100 parts by weight of the total of the acrylic polymer of the copolymer. In the pressure-sensitive adhesive layer according to the present invention, (D) a polyalkylene glycol mono (meth) acrylic acid ester monomer may not be contained in the pressure-sensitive adhesive composition.

Examples of the nitrogen-containing vinyl monomer (E-1) in the component (E) include a vinyl monomer containing an amide bond, a vinyl monomer containing an amino group, and a vinyl monomer having a nitrogen-containing heterocyclic structure. More specifically, there may be mentioned N-vinyl-2-pyrrolidone, N-vinylpyrrolidone, methylvinylpyrrolidone, N- vinylpyridine, N-vinylpiperidone, N- vinylpyrimidine, Substituted vinyls such as N-vinylpyrroles, N-vinylpyrroles, N-vinylimidazoles, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N- A cyclic nitrogen vinyl compound having a heterocyclic structure; (Meth) acryloyl morpholine, N- (meth) acryloylpiperazine, N- (meth) acryloyl aziridine, N- (meth) acryloyl azetidine, N- (Meta) acryloyl-substituted complexes such as N- (meth) acryloylpiperidine, N- (meth) acryloyl azelane, N- A cyclic nitrogen vinyl compound having a cyclic structure; A cyclic nitrogen vinyl compound having a heterocyclic structure having a nitrogen atom such as N-cyclohexylmaleimide or N-phenylmaleimide and an ethylenically unsaturated bond in the ring; Unsubstituted or monoalkyl-substituted (meth) acrylamides such as N-methyl (meth) acrylamide, N-methyl (meth) acrylamide, N-isopropyl (meth) acrylamide and Nt-butyl (meth) acrylamide; (Meth) acrylamide, N, N-diethyl (meth) acrylamide, N, (Meth) acrylamide, N-methyl-N-methyl (meth) acrylamide, N-methyl- Substituted (meth) acrylamides; N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, (Meth) acrylate, N, N-dimethylaminobutyl (meth) acrylate, N, N-diethylaminomethyl (Meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (Meth) acrylate, t-butylaminoethyl (meth) acrylate and the like; N, N-diethylaminopropyl (meth) acrylamide, N, N-dipropylaminopropyl (meth) acrylamide, N, N-diisopropylaminopropyl (Meth) acrylamide, N-methyl-N-isopropylaminopropyl (meth) acrylamide, N-methyl- N, N-dialkyl-substituted aminopropyl (meth) acrylamides such as amides; N-vinylcarboxylic acid amides such as N-vinyl formamide, N-vinylacetamide and N-vinyl-N-methylacetamide; (Meth) acrylamide, N, N-methylenebis (meth) acrylamide, and the like can be used in combination with one or more of N-methoxymethyl (meth) acrylamide, N-ethoxyethyl (Meth) acrylamides; Unsaturated carboxylic acid nitriles such as (meth) acrylonitrile; And the like.

The nitrogen-containing vinyl monomer (E-1) is preferably a compound containing no hydroxyl group, and more preferably a compound containing no hydroxyl group and no carboxyl group. Examples of such monomers include acrylic monomers containing the above-exemplified monomers, for example, N, N-dialkyl substituted amino groups and N, N-dialkyl substituted amide groups; Vinyl-substituted lactams such as N-vinyl-2-pyrrolidone, N-vinylcaprolactam and N-vinyl-2-piperidone; N- (meth) acryloyl-substituted cyclic amines such as N- (meth) acryloylmorpholine and N- (meth) acryloylpyrrolidine are preferred.

(Meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-propoxyethyl (meth) acrylate and the like can be given as examples of the alkyl (meth) (Meth) acrylate, 2-ethoxypropyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, 2- (Meth) acrylate, 2-propoxypropyl (meth) acrylate, 2-isopropoxypropyl (meth) acrylate, 2-butoxypropyl Propyl (meth) acrylate, 3-butoxypropyl (meth) acrylate, 4-methoxybutyl (meth) acrylate, Acrylate, 4-ethoxybutyl (meth) acrylate, 4-propoxybutyl (meth) acrylate, 4-isopropoxybutyl And the like methacrylate, 4-butoxy-butyl (meth) acrylate.

These alkoxy group-containing alkyl (meth) acrylate monomers have a structure in which the atom of the alkyl group in the alkyl (meth) acrylate is substituted with an alkoxy group.

(E-1) a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkyl (meth) acrylate monomer containing an alkoxyl group (E-2) in an amount of from 0 to 20 parts by weight, based on 100 parts by weight of the total of the acrylic- By weight. (E-1) a nitrogen-containing vinyl monomer containing no hydroxyl group and (E-2) an alkyl (meth) acrylate monomer containing an alkoxy group may be used alone or in combination. In the pressure-sensitive adhesive layer according to the present invention, the pressure-sensitive adhesive composition may not contain a nitrogen-containing vinyl monomer or alkoxy group-containing alkyl (meth) acrylate monomer (E)

(F) The isocyanate compound having three or more functional groups may be at least one selected from polyisocyanate compounds having at least three isocyanate (NCO) groups in one molecule, or two or more. The polyisocyanate compound may be classified into an aliphatic isocyanate, an aromatic isocyanate, a non-glycidic isocyanate, and an alicyclic isocyanate. 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) Aromatic isocyanate compounds such as xylylene diisocyanate (XDI), hydrogenated xylylene diisocyanate (H6XDI), dimethyldiphenylenediisocyanate (TOID), and tolylene diisocyanate (TDI).

Examples of the isocyanate compound having three or more functional groups include biuret-modified or isocyanurate-modified products of diisocyanates (compounds having two NCO groups in one molecule), tri- or higher-valent polyols such as trimethylolpropane (TMP) (A compound having at least three or more OH groups in the molecule). It is preferable that the (F) isocyanate compound having three or more functionalities is contained in an amount of 0.5 to 5.0 parts by weight based on 100 parts by weight of the copolymer.

Examples of the isocyanate compound (F) having three or more functional groups used in the present invention include isocyanurate compounds of hexamethylene diisocyanate compounds, isocyanurate compounds of isophorone diisocyanate compounds, and adducts of hexamethylene diisocyanate compounds At least one selected from the group of the first aliphatic isocyanate compounds (F-1) comprising an adduct of an isophorone diisocyanate compound, a burette of a hexamethylene diisocyanate compound, and a burette of an isophorone diisocyanate compound, An isocyanurate of a tolylene diisocyanate compound, an isocyanurate of a xylylene diisocyanate compound, an isocyanurate of a hydrogenated xylylene diisocyanate compound, an adduct of a tolylene diisocyanate compound, a xylylene diisocyanate compound The duct body , And (F-2) the second aromatic isocyanate compound group which is an adduct of hydrogenated xylylene diisocyanate compound. (F-1) first aliphatic isocyanate compound group and (F-2) second aromatic isocyanate compound group are preferably used in combination. In the present invention, at least one or more (F) at least one isocyanate compound selected from the group of the (F-1) first aliphatic isocyanate compounds and the second aromatic isocyanate compound group It is possible to further improve the balance of the adhesive force between the low-speed peeling area and the high-speed peeling area.

The isocyanate compound (F) having a trifunctional or more functional group is preferably at least one selected from the group consisting of the first aliphatic isocyanate compound group (F-1) and the at least one second aromatic isocyanate compound group selected from the group (F-2) , And preferably 0.5 to 5.0 parts by weight based on 100 parts by weight of the copolymer. The mixing ratio of at least one selected from the group consisting of the first aliphatic isocyanate compound group (F-1) and the second aromatic isocyanate compound group (F-2) is (F-1) :( F-2) is in the range of 10%: 90% to 90%: 10% by weight.

Further, the bifunctional (G) bifunctional aliphatic isocyanate compound used in the present invention is alicyclic and alicyclic among the bifunctional isocyanate compounds. The (G) bifunctional aliphatic isocyanate compound is preferably a compound produced by reacting a diisocyanate compound with a diol compound.

For example, a diisocyanate compound can be obtained by reacting a diisocyanate compound with a compound represented by the formula " O = C = NXN = C = O " (where X is divalent) Examples of the compound formed by reacting a diisocyanate compound with a diol compound include compounds represented by the following formula (Z).

(Z)

O = C = NX- (NH-CO-OYO-CO-NH-X) _n -N = C = O

Here, n is an integer of 0 or more. When n is 0, the formula Z represents " O = C = N-X-N = C = O ". (G) bifunctional aliphatic isocyanate compound may include a compound represented by the general formula (Z) in which n is 0 (a diisocyanate compound which is unreacted with respect to the diol compound), but includes a compound in which n is an integer of 1 or more . (G) The bifunctional aliphatic isocyanate compound may be a mixture of a plurality of compounds in which n in the general formula (Z) is different.

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

The diol compound represented by the formula " HO-Y-OH " is an aliphatic diol. Y is preferably a noncyclic, aliphatic divalent. Examples of the diol compound include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, Methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxy pivalate, polyethylene glycol, and polypropylene glycol. It is preferable that it is composed of one kind or two kinds or more selected.

The weight ratio (F / G) of the (F) trifunctional or higher isocyanate compound to the (G) difunctional alicyclic isocyanate compound is preferably 1 to 90.

It is preferable that the total amount of the (F) trifunctional or higher isocyanate compound and (G) bifunctional aliphatic isocyanate compound is 0.1 to 5.0 parts by weight based on 100 parts by weight of the acryl-based polymer.

(H) The antistatic agent is preferably (H-1) an ionic compound having a melting point of 30 to 50 ° C, or an ionic compound containing an acryloyl group (H-2).

In the present invention, as the antistatic agent (H), (H-1) an ionic compound having a melting point of 30 to 50 ° C is added to the copolymer, or the ionic compound containing the (H-2) acryloyl group is copolymerized in the copolymer . It is presumed that these (H) antistatic agents have a low melting point and also have a long chain alkyl group, so that the affinity with the acrylic copolymer is high.

(H-1) As the ionic compound having a melting point of 30 to 50 캜, an ionic compound having a cation and an anion, wherein the cation is at least one selected from the group consisting of pyridinium cation, imidazolium cation, pyrimidinium cation, (PF ₆ ^- ), thiocyanate salt (SCN ^- ), phosphoric acid salt (SCN ^- ), and the like can be used as the anion, Compounds that are inorganic or organic anions such as alkylbenzenesulfonate (RC ₆ H ₄ SO ₃ ^- ), perchlorate (ClO ₄ ^- ), and tetrafluoroborate (BF ₄ ^- ). It is preferably solid at room temperature (for example, 30 ° C), and a melting point of 30 to 50 ° C can be obtained depending on the choice of the chain length of the alkyl group, the position and number of the substituent group, and the like. The cation is preferably a quaternary nitrogen atom onium cation, a quaternary pyridinium cation or a quaternary pyridinium cation such as 1-alkyl pyridinium (the carbon atom at 2-6 may have a substituent or may be unsubstituted) , Quaternary imidazolium cation such as 3-dialkylimidazolium (the carbon atom at the 2, 4 and 5 positions may have a substituent or may be substituted), quaternary ammonium cation such as tetraalkylammonium And the like.

(H-1) It is preferable that the ionic compound having a melting point of 30 to 50 占 폚 is contained in an amount of 0.01 to 5.0 parts by weight based on 100 parts by weight of the copolymer.

Examples of the (H-2) acryloyl group-containing ionic compound include an ionic compound having a cation and an anion such that the cation is a (meth) acryloyloxyalkyltrialkylammonium [R ₃ N ⁺ -C _n H _2n -OCOCQ = CH _2, stage, Q = H or CH _3, R = alkyl] such as (meth) and group-containing cation with acrylic, anion is hexafluorophosphate phosphate (PF ₆ ^-), thiocyanate (SCN ^-), an organic sulfonic acid And inorganic or organic anions such as salts (RSO ₃ ^- ), perchlorate (ClO ₄ ^- ), tetrafluoroborate (BF ₄ ^- ) and F-containing imide salts (R ^F ₂ N ^- ). F-containing already deuyeom (R ^F ₂ N ^-) roneun of R ^F, can be given as a trifluoromethanesulfonyl group, a pentafluorophenyl perfluoroalkyl ethane sulfonyl group, such as an alkane sulfonyl group or a fluoroalkyl sulfonyl group. F contained in an already deuyeom include bis (sulfonyl fluorophenyl) already deuyeom [(FSO _{2) 2} N ^-], bis (trifluoromethane sulfonyl) already deuyeom _{[(CF 3 SO 2) 2 N} - ], bis (Pentafluoroethanesulfonyl) imide salt [(C ₂ F ₅ SO ₂ ) ₂ N ^- ], and the like.

It is preferable that the (H-2) acryloyl group-containing ionic compound is copolymerized in the copolymer in an amount of 0.1 to 5.0% by weight.

Specific examples of the (H) antistatic agent include, but are not particularly limited to, (H-1) Specific examples of the ionic compound having a melting point of 30 to 50 캜 include 1-octylpyridinium hexafluorophosphate, Dodecylpyridinium dodecylbenzenesulfonate, 1-octylpyridinium dodecylbenzenesulfonate, 1-dodecylpyridinium thiocyanate, 1-dodecylpyridinium dodecylbenzene Sulfonic acid salts, 4-methyl-1-octylpyridinium hexafluorophosphate, and the like. Specific examples of the (H-2) acryloyl group-containing ionic compound include dimethylaminomethyl (meth) acrylate hexafluorophosphate salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ = CH ₂ PF ₆ ^-, with the proviso that, Q = H or CH _3], dimethylaminoethyl (meth) (methanesulfonyl-trifluoromethyl) acrylate bis salt imide methyl ^{_{[(CH 3) 3 N + (}} CH 2) 2 OCOCQ = CH 2 (CF ₃ SO ₂ ) ₂ N ^- , where Q = H or CH ₃ , dimethylaminomethyl methacrylate bis (fluorosulfonyl) imide methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ = CH _2. (FSO ₂ ) ₂ N ^- , with Q = H or CH ₃ ].

The pressure-sensitive adhesive composition may optionally contain a polyether-modified siloxane compound. Polyether-modified siloxane compound is a siloxane compound having a polyether, a typical siloxane unit [-SiR ¹ ₂ -O-] In addition, the polyether siloxane having a unit of ^{[-SiR 1 (R 2 O (R} 3 O) n R ⁴ ) -O-]. (Wherein R ¹ represents one or two or more kinds of alkyl groups or aryl groups, R ² and R ³ represent one or two or more kinds of alkylene groups, and R ⁴ represents one or two or more kinds of alkyl groups or acyl groups . Examples of the polyether group include polyoxyalkylene groups such as a polyoxyethylene group [(C ₂ H ₄ O) _n ] and a polyoxypropylene group [(C ₃ H ₆ O) _n ].

The polyether-modified siloxane compound is preferably a polyether-modified siloxane compound having an HLB value of 7 to 12. Further, it is preferable that 0.01 to 0.5 parts by weight of the polyether-modified siloxane compound is contained relative to 100 parts by weight of the copolymer. More preferably, it is 0.1 to 0.5 parts by weight.

HLB is a hydrophilic lipophilic balance (hydrophilic lipophilic ratio) defined by, for example, JIS K3211 (surfactant term).

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 hydrogenated silicon group by a hydrosilylation reaction. Specific examples thereof include dimethylsiloxane · methyl (polyoxyethylene) siloxane copolymer, dimethylsiloxane · methyl (polyoxyethylene) siloxane · methyl (polyoxypropylene) siloxane copolymer, dimethylsiloxane · methyl (polyoxypropylene) .

By blending the polyether-modified siloxane compound into the pressure-sensitive adhesive composition, the pressure-sensitive adhesive and the pressure-sensitive adhesive can be improved. When the pressure-sensitive adhesive composition does not contain a polyether-modified siloxane compound, it becomes more inexpensive.

Further, it is also possible to use other components such as a copolymerizable (meth) acrylic monomer, a (meth) acrylamide monomer, a dialkyl substituted acrylamide monomer, a surfactant, a curing accelerator, a plasticizer, a filler, , An antioxidant, and an antioxidant may be appropriately added. They may be used alone or in combination of two or more.

The subject copolymer used in the pressure-sensitive adhesive composition of the present invention is a monomer copolymerizable with at least one of (A) a (meth) acrylic acid ester monomer having an alkyl group of C4 to C18 in number, and (B) (D) a polyalkylene glycol mono (meth) acrylate monomer; and (E) a nitrogen-containing vinyl monomer or alkoxy group-containing alkyl (meth) acrylate containing no hydroxyl group. ) Acrylate monomers, which are copolymerizable with each other. The polymerization method of the copolymer is not particularly limited, and suitable polymerization methods such as solution polymerization, emulsion polymerization and the like can be used.

When the (H-2) acryloyl group-containing ionic compound (H) is used as the antistatic agent, the copolymer of the subject used in the pressure-sensitive adhesive composition of the present invention is a copolymer of (A) a (meth) (B) a copolymerizable monomer containing a hydroxyl group, (C) a copolymerizable monomer containing a carboxyl group, (D) at least one monomer selected from the group consisting of polyalkylene glycol mono (meth) acrylic acid (E) at least one member selected from the group of copolymerizable monomers consisting of a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkyl (meth) acrylate monomer containing an alkoxy group, at least one member selected from the group consisting of (H-2) Can be synthesized.

The pressure-sensitive adhesive composition of the present invention can be prepared by blending (F) a trifunctional or higher isocyanate compound, (G) a bifunctional aliphatic isocyanate compound, (H) an antistatic agent and any appropriate additives to the copolymer . When the (H-2) acryloyl group-containing ionic compound is polymerized in the copolymer of the subject, (H) an antistatic agent may be further added to the copolymer or may not be added.

The copolymer is preferably an acrylic polymer, and it is preferable that the copolymer contains 50 to 100% by weight of an acrylic monomer such as (meth) acrylate monomer, (meth) acrylic acid or (meth) acrylamide.

The acid value of the acrylic polymer is preferably 0.01 to 8.0. This makes it possible to improve stain resistance and improve the ability to prevent the occurrence of adhesive residue.

Here, " acid value " is one of indices showing the content of acid, and is represented by the number of mg of potassium hydroxide necessary for neutralizing 1 g of a carboxyl group-containing polymer.

It is preferable that the pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition has an adhesive force of 0.05 to 0.1 N / 25 mm at a low speed peeling rate of 0.3 m / min and an adhesive force of 1.0 N / 25 mm or less at a high peeling speed of 30 m / min. As a result, it is possible to obtain a performance in which the adhesive force does not change even by the peeling speed, and it is possible to peel quickly even by high-speed peeling. Further, even when the surface protective film is peeled off once again, an excessive force is not required, and it is easy to peel off from the adherend.

It is preferable that the pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition has a surface resistivity of 5.0 x 10 ⁺ 10? /? Or less and a peeling electrification voltage of 占 0 to 1 kV. In the present invention, "± 0 to 1 kV" means 0 to -1 kV and 0 to +1 kV, that is, -1 to +1 kV. When the surface resistivity is high, the performance for escaping the static electricity generated by the charging at the time of peeling is lowered. Therefore, by sufficiently reducing the surface resistivity, the peeling electrification voltage caused by the static electricity generated when the adherend is peeled off is reduced Thus, it is possible to suppress the influence on the electric control circuit of the adherend or the like.

The gel fraction of the pressure-sensitive adhesive layer (pressure-sensitive adhesive after crosslinking) obtained by crosslinking the pressure-sensitive adhesive composition of the present invention is preferably 95 to 100%. As described above, the high gel fraction lowers the adhesive force at a low rate of peeling, reduces elution of the unpolymerized monomer or oligomer from the copolymer, and improves the reworkability and durability at high temperature and high humidity, The contamination of the complex can be suppressed.

The pressure-sensitive adhesive film of the present invention is formed by forming a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition of the present invention on one side or both sides of a resin film. The surface protective film of the present invention is a surface protective film comprising a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition of the present invention on one side or both sides of a resin film. The pressure-sensitive adhesive composition of the present invention is excellent in antistatic performance, excellent in balance of adhesive force at a low rate of peeling and at a high rate of peeling, and has excellent antistatic properties because the components (A) to (H) , Durability performance and reworkability (no contamination of the adherend after the surface protective film is overlaid with the ballpoint pen through the pressure-sensitive adhesive layer) is also excellent. Therefore, it can be preferably used as a surface protective film of a polarizing plate.

As the base film of the pressure-sensitive adhesive layer or the release film (separator) for protecting the pressure-sensitive adhesive surface, a resin film such as a polyester film or the like can be used.

Antistatic treatment with an antifouling treatment with a silicon-based or fluorine-based releasing agent, a coating agent, fine silica particles, antistatic treatment by application or incorporation of an antistatic agent, etc. can be performed on the surface of the base film opposite to the side where the pressure-

The release film is subjected to releasing treatment by a silicone-based, fluorine-based releasing agent or the like on the side of the pressure-sensitive adhesive layer to be combined with the adhesive surface.

Example

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

≪ Preparation of acrylic copolymer >

[Example 1]

Nitrogen gas was introduced into a reactor equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube to replace the air in the reactor with nitrogen gas. Thereafter, 100 parts by weight of 2-ethylhexyl acrylate, 3.0 parts by weight of 8-hydroxyoctyl acrylate, polypropylene glycol monoacrylate (average number of repeating units of alkylene oxide constituting the polyalkylene glycol chain n = 12) and 60 parts by weight of a solvent (ethyl acetate). Thereafter, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise over 2 hours and reacted at 65 DEG C for 6 hours to obtain an acrylic copolymer solution (1) of Example 1 having a weight average molecular weight of 500,000 . A part of the acrylic copolymer was sampled and used as a measurement sample of the acid value described later.

[Examples 2 to 9 and Comparative Examples 1 to 4]

The acrylic copolymer solution (1) used in Example 1 was obtained in the same manner as in Example 2 except that the monomers were changed to the compositions shown in Table 1 (A) to (E) and (H-2) To 9 and Comparative Examples 1 to 4 were obtained.

≪ Preparation of pressure-sensitive adhesive composition and surface protective film &

[Example 1]

1.5 parts by weight of 1-octylpyridinium hexafluorophosphate was added to the acrylic copolymer solution (1) of Example 1 prepared as described above, and the mixture was stirred. Coronate HX (isocyanate of hexamethylene diisocyanate compound 2.0 parts by weight of the bifunctional alicyclic isocyanate compound G-1 of Synthesis Example 1 and 0.5 parts by weight of the bifunctional aliphatic isocyanate compound G-1 of Synthesis Example 1 were added and stirred to obtain the pressure-sensitive adhesive composition of Example 1. This pressure-sensitive adhesive composition was coated on a release film made of a polyethylene terephthalate (PET) film coated with a silicone resin and dried at 90 ° C to remove the solvent to obtain a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer thickness of 25 μm.

Thereafter, the pressure-sensitive adhesive sheet was transferred onto the surface opposite to the antistatic and antifouling treated surface of a polyethylene terephthalate (PET) film having antistatic and antifouling treatment on one side, Sensitive adhesive layer / release film (PET film coated with silicone resin) ".

[Examples 2 to 9 and Comparative Examples 1 to 4]

The surface protective films of Examples 2 to 9 and Comparative Examples 1 to 4 were prepared in the same manner as the surface protective film of Example 1 except that the compositions of the additives were changed as shown in Table 2 (F) to (H) ≪ / RTI >

Tables 1 and 2 show one table showing the blending ratios of the respective components, and the values of the parts by weight obtained by taking the total of the total of the (A) groups as 100 parts by weight are enclosed in parentheses. Tables 3 and 4 show the compound names of the weak symbols of the respective components used in Tables 1 and 2. D-140N, D-127N, D-110N and D-120N are trade names of Nippon Polyurethane Industry Co., Ltd .; and Coronate (registered trademark) HX, HL and L are trade names of Nippon Polyurethane Industry Co., to be.

In the antistatic agent (H) in Table 1, the quaternary ammonium salt type ionic compound containing the (H-2) acryloyl group copolymerized in the copolymer is described in a column separate from the antistatic agent (H) added after polymerization .

<Synthesis of difunctional aliphatic isocyanate compound>

The bifunctional aliphatic isocyanate compounds of Synthesis Examples 1 to 3 were synthesized by the following methods. As shown in Table 5 and Table 6, the diisocyanate and the diol compound were mixed at a molar ratio of NCO / OH = 16, and the mixture was reacted at 120 ° C for 3 hours. Thereafter, The diisocyanate was removed to obtain the objective bifunctional alicyclic isocyanate compound.

<Test Method and Evaluation>

The surface protective films of Examples 1 to 9 and Comparative Examples 1 to 4 were aged for 7 days in an atmosphere at 23 DEG C and 50% RH, and then a release film (PET film coated with silicone resin) was peeled off to expose the pressure- Was used as a sample for measuring the surface resistivity.

The surface protective film on which the pressure-sensitive adhesive layer was exposed was adhered to the surface of the polarizing plate attached to the liquid crystal cell via the pressure-sensitive adhesive layer, allowed to stand for one day, autoclaved at 50 DEG C and 5 atm for 20 minutes, The sample was left for 12 hours again and used as a sample for measurement of adhesive force, peeling electrification voltage, reworkability and durability.

<Adhesion>

The test specimen obtained by bonding the surface of the polarizing plate with the surface protective film having a width of 25 mm was stretched in the direction of 180 DEG at a low speed peeling speed (0.3 m / min) and a high speed peeling speed (30 m / min) And the peel strength measured was regarded as an adhesive force.

<Surface resistivity>

After aging, a releasing film (PET resin film coated with a silicone resin) was peeled off to form a pressure-sensitive adhesive layer before being adhered to the polarizing plate, and the pressure-sensitive adhesive layer was exposed using a resistivity meter Hiresta UP-HT450 (manufactured by Mitsubishi Chemical Corporation) The surface resistivity was measured.

<Peeling Voltage>

The voltage (high voltage) generated when the polarizing plate was charged by 180 ° peeling at a tensile speed of 30 m / min was measured using a high-precision electrostatic sensor SK-035, SK-200 (manufactured by Keyes Corporation) , And the maximum value of the measured value was taken as the peeling electrification voltage.

<Workability>

The surface protective film of the measurement specimen obtained above was overlaid with a ballpoint pen (load: 500 g, three round trips), and then the surface protective film was peeled off from the polarizing plate to observe the surface of the polarizing plate. The evaluation target standard was "◯" when no pollution was observed on the polarizer, "Δ" when the pollution was confirmed to be at least partially along the locus padded with the ballpoint pen, the contamination was confirmed along the locus of the ballpoint pen, Quot ;, and the case where the release of the pressure-sensitive adhesive was confirmed also from &quot; X &quot;.

<Durability>

The test sample thus obtained was allowed to stand in an atmosphere at 60 DEG C and 90% RH for 250 hours, taken out at room temperature and left for another 12 hours, and then its adhesive strength was measured to confirm that there was no clear increase compared with the initial adhesive strength. The evaluation target standard was evaluated as &quot;? &Quot; when the adhesion after the test was 1.5 times or less than the initial adhesion, and &quot; x &quot;

Table 7 shows the evaluation results. In addition, the surface resistivity is represented by a method of "m × 10 ^{+ n} " being "mE + n" (where m is an arbitrary real number and n is a positive integer).

The surface protective films of Examples 1 to 9 had an adhesive force of 0.05 to 0.1 N / 25 mm at a low speed peeling rate of 0.3 m / min, an adhesive force of 1.0 N / 25 mm or less at a high peeling rate of 30 m / min, is 5.0 × ^{10 +} 10 Ω / □ or less, the peeling electrification voltage is ± 0~1㎸ and, after deotsseun the surface protection film via the adhesive layer above a ball-point pen without contamination proceeds to the adherend, 60 ℃, 90% RH for 250 hours.

(3) excellent antistatic performance; and (4) all of the rework performance, that is, (1) the balance of the adhesive force at the low speed peeling speed and the high speed peeling speed, Demand performance at the same time.

The surface protective film of Comparative Example 1 does not contain all of the (F) trifunctional or higher isocyanate compound and (G) bifunctional aliphatic isocyanate compound to be the crosslinking agent, or the low-rate peeling rate of 0.3 m / min and the high- / min, the surface resistivity and the peeling electrification voltage were high, and the reworkability and durability were poor.

The surface protective film of Comparative Example 2 contained the (G) bifunctional aliphatic isocyanate compound instead of the bifunctional alicyclic isocyanate compound, and the bifunctional ring-containing diisocyanate compound as the bifunctional cyclic isocyanate compound, or the high-speed peeling speed of 30 m / min The adhesive strength was too large and durability was poor.

In the surface protective film of Comparative Example 3, since the (F) trifunctional or higher isocyanate compound was excessive, (G) the bifunctional alicyclic isocyanate compound was not contained, the port life was too short and the crosslinking proceeded before application , I could not do the pottery.

The surface protective film of Comparative Example 4 had too much (G) bifunctional aliphatic aliphatic isocyanate compound (F) as compared with the trifunctional or higher isocyanate compound, or the adhesive strength at the high-speed peeling rate of 30 m / min was too large and durability was poor.

As described above, in the surface protective films of Comparative Examples 1 to 4, it was found that (1) balance of the adhesive force at a low speed peeling speed and a high speed peeling speed, (2) prevention of occurrence of adhesive residue, Preventing performance and (4) all the required performance of the rework performance.

Claims (5)

(A) at least one kind of (meth) acrylic acid ester monomer having an alkyl group of C4 to C18 in the alkyl group, (B) a copolymerizable monomer containing a hydroxyl group, and (C) a carboxyl group-containing copolymerizable monomer, (D) a polyalkylene glycol mono (meth) acrylate monomer, (E) a nitrogen-containing vinyl monomer containing no hydroxyl group, or an alkoxy (Meth) acrylate monomer and a copolymerizable monomer group selected from the group consisting of an alkyl (meth) acrylate monomer,
Wherein the pressure-sensitive adhesive composition comprises (F) an isocyanate compound having three or more functional groups, (G) a bifunctional alicyclic isocyanate compound, and (H) an ionic compound having a melting point of 30 to 50 DEG C ,
(F) a trifunctional or higher isocyanate compound and (G) a bifunctional aliphatic isocyanate compound in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the total of the acrylic polymer,
The weight ratio (F / G) of the (F) trifunctional or higher isocyanate compound to the (G) bifunctional alicyclic isocyanate compound is from 1 to 90,
(Meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate and 2-hydroxyethyl (Meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide and N-hydroxyethyl (meth) acrylamide. The method according to claim 1,
When the total amount of the acrylic polymer of the copolymer is 100 parts by weight,
(A) 50 to 91 parts by weight of a (meth) acrylic acid ester monomer having an alkyl group having 4 to 18 carbon atoms,
0.1 to 10 parts by weight of the copolymerizable monomer containing the hydroxyl group (B)
0 to 1.0 part by weight of the copolymerizable monomer containing the carboxyl group (C)
0 to 50 parts by weight of (D) the polyalkylene glycol mono (meth) acrylate monomer,
(E) a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkyl (meth) acrylate monomer containing an alkoxy group at a ratio of 0 to 20 parts by weight. 3. The method according to claim 1 or 2,
(Meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethylhexahydrophthalic acid, 2- (Meth) acryloyloxyethylmaleic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxyethylsuccinic acid, 2- Caprolactone mono (meth) acrylate, 2- (meth) acryloyloxyethyltetrahydrophthalic acid, and the like.
Wherein the polyalkylene glycol mono (meth) acrylate monomer (D) is at least one selected from the group consisting of polyalkylene glycol mono (meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, ethoxypolyalkylene glycol At least one kind selected from the group consisting of the following. A surface protective film comprising a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition of claim 1 or 2 on one or both surfaces of a resin film. 5. The method of claim 4,
A surface protective film used as a surface protective film of a polarizing plate.