KR101733957B1 - Surface protection film - Google Patents

Abstract

The present invention provides a pressure-sensitive adhesive composition which has excellent antistatic performance and is excellent in balance of adhesive force at a low speed peeling speed and a high speed peeling speed, and also has excellent durability 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, ) Trifunctional or higher isocyanate compound, (G) a crosslinking retarder, (H) a crosslinking catalyst, and (I) an antistatic agent, wherein the acid value of the acrylic polymer is from 0.01 to 8.0.

Description

Surface Protective Film {SURFACE PROTECTION FILM}

The present invention relates to a surface protective film used in a manufacturing process of a liquid crystal display. More particularly, the present invention relates to a surface protective film for use in protecting the surface of an optical member such as a polarizing plate and a retarder by adhering (sticking) (sticking) the surface of an optical member such as a polarizing plate, Sensitive adhesive composition 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 a low surface tension, there arises a problem of peeling phenomenon such as lifting due to heating during processing or storage, There was a problem that the re-peelability was poor.

(A) 100 parts by weight of 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, (b) , And (c) 3 to 100 parts by weight of a vinyl ester of an aliphatic carboxylic acid having 1 to 5 carbon atoms are added to a copolymer of a monomer mixture containing a crosslinking agent equivalent to the carboxyl group of the component (b) A pressure-sensitive adhesive composition has been proposed (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 An antistatic agent, and (e) a polymeric antistatic agent obtained by polymerizing the above-mentioned antistatic agent in a high molecular weight (Patent Document 3).

Further, in recent years, it has been proposed to incorporate such an antistatic agent in a direct adhesive layer without being contained in the base film or on 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. That is, it is difficult to peel off when it is mistakenly bonded, and it is apt to be difficult to reattach. Therefore, it may be considered 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 obtain the reworkability.

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. The required performance can be satisfied, but all required performance required for the pressure-sensitive adhesive layer of the surface protective film can not be satisfied.

It is an object of the present invention to provide a pressure-sensitive adhesive composition and a surface protective film excellent in balance of adhesive force and excellent in durability and rework performance at low and high speed peeling speeds do. It is another object of the present invention to provide a pressure-sensitive adhesive composition and a surface protective film having excellent antistatic properties in addition to the above performance.

(B) a copolymerizable monomer containing a hydroxyl group; and (C) a copolymerizable (meth) acrylic monomer containing a carboxyl group, wherein the (meth) acrylic acid ester monomer (Meth) acrylic acid ester monomer having a hydroxyl group and (D) a polyalkylene glycol mono (meth) acrylate monomer having at least one nitrogen-containing vinyl monomer or alkoxy group-containing alkyl (F) a trifunctional or higher isocyanate compound, (G) a crosslinking retarder, and (H) a crosslinking catalyst, wherein the acid value of the acrylic polymer is from 0.01 to 8.0, (D) a polyalkylene glycol mono (meth) acrylic acid ester monomer having an average number of repeats of an alkylene oxide constituting a polyalkylene glycol chain of 3 to 14 It provides compositions.

(I) an antistatic agent is contained in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the copolymer; and (B) the antistatic agent is contained in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the copolymer. Or a quaternary ammonium salt type ionic compound having an acryloyl group copolymerized in the copolymer in an amount of from 0.1 to 5.0% by weight.

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 or more compounds selected from the group of compounds consisting of hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide and N- , And 0.1 to 5.0 parts by weight of a copolymerizable monomer containing the hydroxyl group (B), based on 100 parts by weight of the (meth) acrylate monomer having (A) the alkyl group of C4 to C18, (Meth) acrylate, 6-hydroxyhexyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate in the copolymerizable monomer (B) Parts by weight,

Wherein the copolymerizable monomer containing a carboxyl group is at least one selected from the group consisting of (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethylhexahydrophthalic acid, 2- (Meth) acryloyloxyethylmaleic acid, 2- (meth) acryloyloxyethylmaleic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (Meth) acryloyloxyethyltetrahydrophthalic acid, and (A) the (meth) acryloyloxyethyltetrahydrophthalic acid is at least one selected from the group consisting of (meth) acrylic acid, (C) a copolymerizable monomer containing a carboxyl group is contained in an amount of 0.35 to 1.0 part by weight based on 100 parts by weight of the acrylic ester monomer.

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 it is preferable that the (A) alkyl group is contained in an amount of 1 to 50 parts by weight based on 100 parts by weight of the (meth) acrylic acid ester monomer having C4 to C18 alkyl groups.

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 isophorone diisocyanate compound of the hexamethylene 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.

The nitrogen-containing vinyl monomer or alkoxy group-containing alkyl (meth) acrylate monomer (E) containing no hydroxyl group may be used in an amount of 100 parts by weight of the (meth) acrylate monomer having an alkyl group of C4 to C18 By weight based on the total weight of the composition.

It is also preferable that the isocyanate compound (F) having three or more functional groups is contained in an amount of 0.5 to 5.0 parts by weight based on 100 parts by weight of the copolymer.

The crosslinking retarder (G) is a keto-enol tautomeric compound, and 1.0 to 5.0 parts by weight of the crosslinking retarder (G) is contained relative to 100 parts by weight of the copolymer,

It is preferable that the (H) crosslinking catalyst is an organotin compound, and the crosslinking catalyst (H) is contained in an amount of 0.01 to 0.5 parts by weight based on 100 parts by weight of the copolymer.

The pressure-sensitive adhesive layer obtained 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 rate of 30 m / desirable.

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 0.3 kV.

The present invention also provides a pressure-sensitive adhesive 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 present invention relates to a surface protective film comprising a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition on one surface of a resin film, wherein the surface protective film is covered with a ballpoint pen through the pressure- And the surface protective film is characterized by being free of the surface protective 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 opposite to the side where the pressure-sensitive adhesive layer of the resin film 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.

Also, when the average number of repeating units of the alkylene oxide constituting the polyalkylene glycol chain of the polyalkylene glycol mono (meth) acrylic acid ester monomer (D) is 3 to 14, the antistatic function is improved, Workability) can be improved.

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

The pressure-sensitive adhesive composition of the present invention,

(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, (D) a polyalkylene glycol mono (meth) acrylate having an acid value of from 0.01 to 8.0, and (D) an isocyanate compound having at least three functional groups, And the average number of repeats of the alkylene oxide constituting the polyalkylene glycol chain of the acrylic ester monomer is 3 to 14.

The pressure-sensitive adhesive composition of the present invention further comprises (I) an antistatic agent, wherein the antistatic agent (I) is contained in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the copolymer, To 50 ° C, or an acryloyl group-containing quaternary ammonium salt type ionic compound copolymerized in the copolymer in an amount of 0.1 to 5.0% 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.

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.

It is preferable that 0.1 to 5.0 parts by weight of the copolymerizable monomer containing the hydroxyl group (B) is contained relative to 100 parts by weight of the (meth) acrylic ester monomer having (A) the alkyl group of C4 to C18.

The total amount of 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate among the copolymerizable monomer (B) Is preferably less than or equal to 0 parts by weight, and more preferably 0 to 0.9 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.

(C) a copolymerizable monomer containing a carboxyl group in an amount of from 0.35 to 1.0 part by weight, more preferably from 0.35 to 1.0 part by weight, based on 100 parts by weight of (meth) acrylic acid ester monomer having (A) .

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.

(Meth) acrylate monomer (D) is contained in an amount of 1 to 50 parts by weight based on 100 parts by weight of the (meth) acrylic ester monomer having (A) the alkyl group of C4 to C18.

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.

(Meth) acrylate monomer having an alkyl group having a carbon number of C4 to C18 of 100 to 100 (meth) acrylic acid ester monomers having (E) a hydroxyl group-containing nitrogen-containing vinyl monomer or Is preferably contained in an amount of 1 to 20 parts by weight based on 100 parts 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.

(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) the first aliphatic isocyanate compound group and (F-2) the 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.

(G) As the crosslinking retarder, β-keto esters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoate, oleyl acetoacetate, lauryl acetoacetate and stearyl acetoate, acetyl acetone, 2,4- Dione, and benzoyl acetone. These are keto-enol tautomeric compounds, and in the pressure-sensitive adhesive composition using a polyisocyanate compound as a cross-linking agent, by blocking the isocyanate group of the cross-linking agent, excessive viscosity increase or gelation of the pressure- Can extend the life of the port.

The crosslinking retarder (G) is preferably a keto-enol tautomer compound, and is preferably at least one selected from the group consisting of acetylacetone and ethyl acetoacetate.

(G) The crosslinking retarder is preferably contained in an amount of 1.0 to 5.0 parts by weight based on 100 parts by weight of the copolymer.

(H) crosslinking catalyst may be any substance that functions as a catalyst for the reaction (crosslinking reaction) between the copolymer and the crosslinking agent in the case where the polyisocyanate compound is used as a crosslinking agent, and may be an amine compound such as a tertiary amine, , An organic lead compound, an organic zinc compound, and the like.

Examples of tertiary amines include trialkylamines, N, N, N ', N'-tetraalkyldiamines, N, N-dialkylaminoalcohols, triethylenediamine, morpholine derivatives and piperazine derivatives .

Examples of the organotin compounds include dialkyltin oxide, dialkyltin fatty acid salts, and stannous primary fatty acid salts.

(H) The crosslinking catalyst is preferably an organotin compound, and more preferably at least one member selected from the group consisting of dioctyltin oxide and dioctyltin dilaurate.

(H) crosslinking catalyst is preferably contained in an amount of 0.01 to 0.5 parts by weight based on 100 parts by weight of the copolymer.

The antistatic agent (I) is preferably an ionic compound (I-1) having a melting point of 30 to 50 캜 or a quaternary ammonium salt-type ionic compound containing an acryloyl group (I-2).

(I-1) an ionic compound having a melting point of 30 to 50 占 폚 is added to the copolymer, or (I-2) an acryloyl group-containing quaternary ammonium salt type ionic compound is added to the copolymer And copolymerized during coalescence. It is presumed that these (I) antistatic agents have a low melting point and also have a long-chain alkyl group and therefore have high affinity with an acrylic copolymer.

(I-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 a pyridinium cation, an imidazolium cation, a pyrimidinium cation, (PF ₆ ^- ), thiocyanate salt (SCN ^- ), phosphoric acid salt (SCN ^- ), and the like, 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.

(I-1) The ionic compound having a melting point of 30 to 50 占 폚 is preferably contained in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the copolymer.

(I-2) acryloyl group-containing quaternary ammonium salt type ionic compound, an ionic compound having a cation and an anion, wherein the cation is a (meth) acryloyloxyalkyltrialkylammonium [R ₃ N ⁺ -C _n (PF ₆ ^- ), a thiocyanate ((R 2) 2), a quaternary ammonium group containing a (meth) acryloyl group such as H _2n --OCOCQCH ₂ wherein Q is H or CH ₃ , A compound which is an inorganic or organic anion such as SCN ^- , an organic sulfonate (RSO ₃ ^- ), perchlorate (ClO ₄ ^- ), tetrafluoroborate (BF ₄ ^- ) and F ^- containing imide salt (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.

(I-2) acryloyl group-containing quaternary ammonium salt type ionic compound is preferably copolymerized in the copolymer in an amount of from 0.1 to 5.0% by weight.

Specific examples of the (I) antistatic agent include, but are not limited to, (I-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 (IV-2) acryloyl group-containing quaternary ammonium salt type ionic compound include dimethylaminomethyl (meth) acrylate hexafluorophosphate methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ = CH ₂ · PF ₆ ^-, stage, 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 (J) a polyether-modified siloxane compound. (J) a polyether-modified siloxane compound is a siloxane compound having a polyether, a typical siloxane unit [-SiR ¹ ₂ -O-] In addition, the siloxane units having polyether ^{[-SiR 1 (R 2 O (R} 3 O ) _n R ⁴⁾ has a -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 ].

(J) 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 (J) 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) .

(J) The blend of the polyether-modified siloxane compound and the pressure-sensitive adhesive composition can improve the adhesive force and the workability of the pressure-sensitive adhesive. When the pressure-sensitive adhesive composition does not contain the polyether-modified siloxane compound (J), the cost is lower.

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.

(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 carboxyl group-containing , And (D) a polyalkylene glycol mono (meth) acrylic acid ester monomer. 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 quaternary ammonium salt type ionic compound (I-2) containing an acryloyl group is used as the antistatic agent (I) as the antistatic agent, the subject copolymer used in the pressure-sensitive adhesive composition of the present invention preferably has (A) (Meth) acrylate monomer, (B) a copolymerizable monomer containing a hydroxyl group, (C) a copolymerizable monomer containing a carboxyl group, (D) a polyalkylene glycol mono (meth) acrylic acid ester monomer, and I-2) acryloyl group-containing quaternary ammonium salt type ionic compound.

The pressure-sensitive adhesive composition of the present invention is prepared by blending (F) a trifunctional or higher isocyanate compound, (G) a crosslinking retarder, (H) a crosslinking catalyst, (I) an antistatic agent, . When the (I-2) acryloyl group-containing quaternary ammonium salt type ionic compound is polymerized in the copolymer of the subject, the antistatic agent (I) 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 speed of 0.3 m / min and an adhesive force of 1.0 N / 25 mm or less at a high speed peeling speed of 30 m / . 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 0.3 kV. In the present invention, "± 0 to 0.3 kV" means 0 to -0.3 kV and 0 to +0.3 kV, that is, -0.3 to +0.3 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 of a resin film. Since the pressure-sensitive adhesive composition of the present invention has the components (A) to (I) in a well-balanced manner, it has excellent antistatic properties, , 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.

Examples 1 to 9 and Comparative Examples 1 to 4 of a pressure-sensitive adhesive composition and a surface-protective film containing no antistatic agent were shown below.

≪ Preparation of acrylic copolymer (1) >

[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. Then, 100 parts by weight of 2-ethylhexyl acrylate, 0.9 part by weight of 8-hydroxyoctyl acrylate, 0.5 part by weight of acrylic acid, polypropylene glycol monoacrylate (alkylene oxide constituting polyalkylene glycol chain 10 parts by weight of an average number of repeating units of n = 12) and 5 parts by weight of N-vinylpyrrolidone were added 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]

Examples 2 to 9 and Comparative Example 1 were prepared in the same manner as in the acrylic copolymer solution (1) used in Example 1 except that the monomers were changed to the compositions shown in Table 1 (A) to (E) To obtain an acrylic copolymer solution for use in Examples 1-4.

≪ Preparation of pressure-sensitive adhesive composition and surface protective film (1) >

[Example 1]

2.5 parts by weight of acetylacetone was added to the acrylic copolymer solution (1) of Example 1 thus prepared and stirred. Then, 1.0 part by weight of Coronate HX (isocyanurate of hexamethylene diisocyanate compound) , 0.2 part by weight of coronate L (an adduct of trimethylolpropane in the tolylene diisocyanate compound) and 0.02 part by weight of dioctyltin dilaurate were added and stirred to obtain a 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 of the polyethylene terephthalate (PET) film which was antistatic and antifouling-treated on one side of the surface opposite to the antistatic and antifouling treated surface to obtain a PET film / Pressure-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 in 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 dividing the composition ratio of each component into two. The numerical values of parts by weight obtained by taking the total of (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.

<Test Method and Evaluation>

The surface protective films of Examples 1 to 9 and Comparative Examples 1 to 4 were aged for 7 days under an atmosphere of 23 ° C and 50% RH. Thereafter, the release film (PET film coated with silicone resin) was peeled off to expose the pressure-sensitive adhesive layer. 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, And left for another 12 hours was used as a measurement sample for adhesion, reworkability and durability.

<Acid value>

The acid value of the acrylic polymer was dissolved in a solvent (diethyl ether and ethanol mixed at a volume ratio of 2: 1), and the concentration of the acid polymer was measured using a potentiometric automatic titrator (AT-610, Potassium titanate ethanol solution with mol / l was subjected to potentiometric titration to determine the amount of potassium hydroxide ethanol solution needed to neutralize the sample. From the following equation, the acid value was calculated.

Acid value = (B x f x 5.611) / S

B = Amount (ml) of 0.1 mol / l potassium hydroxide ethanol solution used for titration,

f = factor of 0.1 mol / l potassium hydroxide ethanol solution

S = mass of solids in the sample (g)

<Adhesion>

The measurement specimen obtained by bonding the surface protective film having a width of 25 mm to the surface of the polarizing plate obtained above was measured at a low speed peeling speed (0.3 m / min) and a high peeling speed (30 m / min) min, peeling strength measured by peeling was regarded as adhesive force.

<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 criteria of the evaluation target were "◯" when there was no contamination on the polarizer, "△" when the contamination was confirmed at least in part along the locus of the ballpoint pen, and when the contamination was confirmed along the locus, The case where the release of the pressure-sensitive adhesive from the surface was confirmed was evaluated as &quot; X &quot;.

<Durability>

The sample thus obtained was allowed to stand in an atmosphere at 60 DEG C and 90% RH for 250 hours, and then taken out at room temperature. After leaving for 12 hours, the adhesive strength was measured and it was confirmed 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 5 shows the evaluation results.

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 / , The surface of the surface protective film was covered with a ballpoint pen. There was no contamination on the adherend, and durability was excellent when the film was allowed to stand in an atmosphere at 60 DEG C and 90% RH for 250 hours.

That is, (1) balance the adhesive force at the low-speed peeling speed and the high-speed peeling speed, (2) prevent the occurrence of the adhesive residue, and (3) satisfy all the required performance of the rework performance.

The average number of repeats of the alkylene oxide constituting the polyalkylene glycol chain of the polyalkylene glycol mono (meth) acrylic acid ester monomer (D) is 3 to 14, thereby further improving the stain resistance (reworkability) I could.

The surface protective film of Comparative Example 1 contains (D) a polyalkylene glycol mono (meth) acrylate monomer and (E) a nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth) acrylate monomer and (F) an isocyanate compound , The adhesive force at the low speed peeling speed of 0.3 m / min and the high peeling speed of 30 m / min was excessively large, resulting in poor reworkability and durability.

In the surface protective film of Comparative Example 2, the average number of repeating units of the alkylene oxide constituting the polyalkylene glycol chain in the polyalkylene glycol mono (meth) acrylate monomer (D) n) is excessive, and (E) a nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth) acrylate monomer is not contained, the reworkability and durability are poor.

The surface protective film of Comparative Example 3 could not be coated because (F) the isocyanate compound was excessive, (G) the crosslinking retarder was not blended, the pot life was too short, and the crosslinking proceeded before application .

The surface protective film of Comparative Example 4 could not be coated because (F) the isocyanate compound was excessive, (H) the port life was too short even without the crosslinking catalyst, and the crosslinking proceeded before application.

As described above, in the surface protective films of Comparative Examples 1 to 4, (1) balance of adhesive force at a low speed peeling speed and a high speed peeling speed, (2) prevention of occurrence of adhesive residue, and It was not possible to satisfy all the required performance of the performance at the same time.

Examples 11 to 19 and Comparative Examples 11 to 14 of a pressure-sensitive adhesive composition and a surface protective film containing an antistatic agent were shown below.

[Example 11]

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. Then, 100 parts by weight of 2-ethylhexyl acrylate, 0.9 part by weight of 8-hydroxyoctyl acrylate, 0.5 part by weight of acrylic acid, polypropylene glycol monoacrylate (alkylene oxide constituting polyalkylene glycol chain 10 parts by weight of an average number of repeating units of n = 12) and 5 parts by weight of N-vinylpyrrolidone were added 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 12 to 19 and Comparative Examples 11 to 14]

The acrylic copolymer solution (1) used in Example 11 was obtained in the same manner as the acrylic copolymer solution (1) in Example 12 except that the monomers were changed to the compositions of (A) to (E) To 19 and Comparative Examples 11 to 14 were obtained.

&Lt; Preparation of pressure-sensitive adhesive composition and surface protective film (2) &gt;

[Example 11]

1.5 parts by weight of 1-octylpyridinium hexafluorophosphate and 2.5 parts by weight of acetylacetone were added to the acrylic copolymer solution (1) of Example 11 prepared as described above, followed by stirring. Coronate HX (hexamethylene diisocyanate , 0.2 part by weight of coronate L (an adduct of an isocyanate compound with trimethylolpropane in the tolylene diisocyanate compound) and 0.02 part by weight of dioctyltin dilaurate were added, stirred, and mixed. A pressure-sensitive adhesive composition of Example 1 was obtained. 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) &quot;.

[Examples 12 to 19 and Comparative Examples 11 to 14]

The surface protective films of Examples 11 to 19 and Comparative Examples 11 to 14 were prepared in the same manner as in the surface protective film of Example 11 except that the compositions of the additives were changed as shown in Table 6 (F) to (I-1) A surface protective film was obtained.

Tables 6 and 7 show one table showing the compounding ratio of each component, and the values of the parts by weight obtained by taking the total of the group (A) as 100 parts by weight are enclosed in parentheses. In Table 6 and Table 7, the chemical names of the weak symbols of the respective components are the same as those shown in Tables 3 and 4 above. 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 Table 6, (I) the quaternary ammonium salt type ionic compound (I-2) copolymerized in the copolymer among the antistatic agent (I) is the quaternary ammonium salt type ionic compound containing acryloyl group, .

In Table 7, (I) the antistatic agent (I-1) to be added after polymerization of the copolymer is an ionic compound having a melting point of 30 to 50 占 폚, .

&Lt; Test method and evaluation (2) &gt;

After the surface protective films of Examples 11 to 19 and Comparative Examples 11 to 14 were aged for 7 days in an atmosphere of 23 ° C and 50% RH, a release film (PET resin film coated with a silicone resin) was peeled off to form a pressure- The thus-exposed sample 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.

<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 (voltage) generated as a result of charging the polarizing plate when the measurement sample thus obtained was peeled by 180 ° at a tensile rate of 30 m / min was measured with 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.

The test methods for the acid value, the adhesion, the workability and the durability were the same as those of Examples 1 to 9 and Comparative Examples 1 to 9 in the pressure-sensitive adhesive composition and the surface- 4 is the same as the test method.

Table 9 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 11 to 19 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 / is 5.0 × ^{10 +} 10 Ω / □ or less, the peeling electrification voltage is ± 0~0.3㎸ 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 average number of repeats of the alkylene oxide constituting the polyalkylene glycol chain of the polyalkylene glycol mono (meth) acrylic acid ester monomer (D) is 3 to 14, so that the antistatic function is improved. Further, Reworkability) can be improved.

The surface protective film of Comparative Example 11 contains (D) a polyalkylene glycol mono (meth) acrylic acid ester monomer and (E) a nitrogen-containing vinyl monomer or alkoxy group-containing alkyl (meth) acrylate monomer and (F) an isocyanate compound The adhesive force at the low speed peeling speed of 0.3 m / min and the high peeling speed of 30 m / min was excessively large, the surface resistivity and the peeling voltage were high, and the reworkability and durability were poor.

In the surface protective film of Comparative Example 12, the hydroxyl group-containing monomer (B) was under-produced, and the average repeating number of the alkylene oxide constituting the polyalkylene glycol chain in the polyalkylene glycol mono (meth) (n) is too high, and (E) it does not contain a nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth) acrylate monomer, the surface resistivity and the peeling electrification voltage are high and the reworkability and durability are poor.

The surface protective film of Comparative Example 13 could not be coated because (F) the isocyanate compound was excessive, (G) the crosslinking retarder was not blended, the pot life was too short, and the crosslinking proceeded before application .

The surface protective film of Comparative Example 14 could not be coated because (F) the isocyanate compound was excessive, (H) the port life was too short even without the crosslinking catalyst, and the crosslinking proceeded before application.

As described above, in the surface protective films of Comparative Examples 11 to 14, it was found that (1) balance of the adhesive force at a low rate of peeling and a high rate of peeling were achieved, (2) Preventing performance and (4) all the required performance of the rework performance.

Claims (3)

A surface protective film comprising a pressure-sensitive adhesive composition containing an acrylic polymer, an antistatic agent and a crosslinking agent formed on one side of a resin film,
(D) a copolymerizable monomer containing (C) a carboxyl group, (D) a copolymerizable monomer containing a carboxyl group, and (D) a copolymerizable monomer having a carboxyl group, (E) a copolymer obtained by copolymerizing at least one of a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkoxy group-containing alkyl (meth) acrylate monomer containing no hydroxyl group, with a polyalkylene glycol mono (meth) Of an acrylic polymer,
Wherein the pressure-sensitive adhesive composition further comprises an isocyanate compound (F) having three or more functional groups as the crosslinking agent, (G) a crosslinking retarder, and (H) a crosslinking catalyst,
Wherein the pressure-sensitive adhesive layer has an adhesive force of 0.05 to 0.1 N / 25 mm at a low speed peeling speed of 0.3 m / min and an adhesive force of 1.0 N / 25 mm or less at a high speed peeling speed of 30 m / min. The method according to claim 1,
(Meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, At least one compound selected from the group consisting of ethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide and N-hydroxyethyl
Wherein 0.1 to 5.0 parts by weight of a copolymerizable monomer containing the hydroxyl group (B) is contained in 100 parts by weight of the (meth) acrylic ester monomer having (A) the alkyl group of C4 to C18, (Meth) acrylate, 6-hydroxyhexyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate in the copolymerizable monomer containing hydroxyl group is 0 to 0.9 part by weight (Meth) acrylate, 6-hydroxyhexyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate,
Wherein the copolymerizable monomer containing a carboxyl group is at least one selected from the group consisting of (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethylhexahydrophthalic acid, 2- (Meth) acryloyloxyethylmaleic acid, 2- (meth) acryloyloxyethylmaleic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- At least one member selected from the group consisting of polycaprolactone mono (meth) acrylate and 2- (meth) acryloyloxyethyltetrahydrophthalic acid,
The acid value of the acryl-based polymer is 0.01 to 8.0,
Wherein the copolymerizable monomer containing the carboxyl group (C) is contained in an amount of 0.35 to 1.0 part by weight based on 100 parts by weight of the (meth) acrylic acid ester monomer having (A) the alkyl group of C4 to C18. 3. The method according to claim 1 or 2,
Wherein the (D) polyalkylene glycol mono (meth) acrylic acid ester monomer has an average number of repeating alkylene oxides constituting the polyalkylene glycol chain of 3 to 14,
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 And 1 to 50 parts by weight, relative to 100 parts by weight of the (meth) acrylic acid ester monomer in which the alkyl group of the (A) alkyl group has from 4 to 18 carbon atoms,
(Meth) acrylic acid ester monomer (A) having an alkyl group of C4 to C18 in the alkyl group (A), the nitrogen-containing vinyl monomer containing no hydroxyl group or the alkoxy group- 1 to 20 parts by weight with respect to 100 parts by weight,
, 0.5 to 5.0 parts by weight of the (F) trifunctional or higher isocyanate compound is contained per 100 parts by weight of the copolymer,
Wherein the crosslinking retarder (G) is a keto-enol tautomeric compound, 1.0 to 5.0 parts by weight of the crosslinking retarder (G) is added to 100 parts by weight of the copolymer,
Wherein the crosslinking catalyst (H) is an organotin compound and 0.01 to 0.5 parts by weight of the crosslinking catalyst (H) is contained relative to 100 parts by weight of the copolymer,
Wherein the antistatic agent (I) is an ionic compound which is solid at 30 占 폚 and has a melting point of 30 to 50 占 폚, the antistatic agent being contained in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the copolymer, Wherein the surface protective film is an acryloyl group-containing quaternary ammonium salt type ionic compound copolymerized in a proportion of 0.1 to 5.0 wt%.