KR20170110561A - Adhesive composition and surface protection film - Google Patents

Abstract

The present invention provides a pressure-sensitive adhesive composition and a surface protective film having a long pot life and a high crosslinking speed without using an organotin compound. (C) relative to 100 parts by weight of a copolymer of a copolymerizable monomer containing a hydroxyl group (B) as a copolymerizable monomer group with at least one (meth) acrylate monomer having an alkyl group of C4 to C18 in the alkyl group (A) (E) 0.1 to 10 parts by weight of a bifunctional or higher functional isocyanate compound, (D) 0.001 to 0.5 part by weight of a crosslinking catalyst of a metal chelate compound, and (E) / (D) is 70-1000.

Description

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

The present invention relates to a pressure-sensitive adhesive composition and a surface protective film. More specifically, since the use of an organotin compound that adversely affects the environment has been restricted in recent years, the use of a crosslinking catalyst of a metal chelate compound other than an organotin compound results in a long pot life without using an organotin compound, Sensitive adhesive composition and a surface protective film.

As the pressure-sensitive adhesive composition for optical use, an acrylic pressure-sensitive adhesive comprising a copolymer obtained by copolymerizing an alkyl (meth) acrylate as a main component and an acrylic monomer having a hydroxyl group or a carboxyl group as a functional group is preferably used . In addition, it is required that various physical properties such as the adhesive strength of the pressure-sensitive adhesive layer are appropriately adjusted. Particularly, the pressure-sensitive adhesive layer for a surface protective film is suitable for bonding a surface protective film with an automatic bonding apparatus so as to be suitable for a manufacturing process of a factory production, and is excellent in balance of adhesive force at low- A pressure-sensitive adhesive layer is required. In addition to the balance of the adhesive force, a pressure-sensitive adhesive composition having a long pot life and excellent various physical properties is required.

A method of adjusting various physical properties of the pressure-sensitive adhesive layer is to perform a crosslinking reaction using an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, or the like, which reacts with a functional group such as a hydroxyl group or a carboxyl group contained in an acrylic pressure- Cohesion force and the like.

BACKGROUND ART Conventionally, isocyanate-based crosslinking agents have been widely used as crosslinking agents for acrylic pressure-sensitive adhesives. Further, in the crosslinking reaction using an isocyanate crosslinking agent, a metal chelate is frequently used as a catalyst for promoting the crosslinking reaction.

In general, dibutyltin dilaurate, which is an organic tin compound, has been used as a catalyst for the cross-linking reaction because of the excellent reaction rate of the cross-linking reaction, but the dibutyltin compound has been avoided from its point of view of harmful toxicity .

For this reason, there is a demand for a crosslinking catalyst that is a substitute for a dibutyltin compound used in combination with an isocyanate crosslinking agent, is inexpensive, and has an excellent reaction rate of the crosslinking reaction.

Among them, Patent Document 1 discloses iron chelates as metal chelates as crosslinking catalysts used in combination with isocyanate crosslinking agents, and tris (acetylacetonate) iron is particularly preferred because of its excellent catalytic activity.

However, the acrylic pressure-sensitive adhesive composition containing a crosslinking catalyst gradually undergoes a crosslinking reaction even when it is left at room temperature. For this reason, in the industrial production of the pressure-sensitive adhesive, a crosslinking catalyst and a reaction retarder are generally used together to stop the crosslinking reaction until the time when the raw material of the pressure-sensitive adhesive composition is blended and the crosslinking reaction is started.

Regarding the combination of the crosslinking catalyst and the reaction retarder, Patent Document 2 discloses a method for producing a polyurethane comprising a mixture of at least one metal acetylacetonate and acetylacetone, wherein the metal acetylacetonate and the acetylacetone Discloses the use of a reaction urethane mixture comprising a catalyst system in a weight ratio of 2: 1.

Japanese Laid-Open Patent Publication No. 2011-001440 Japanese Patent Application Laid-Open No. 2008-285681

In the pressure-sensitive adhesive composition described in Patent Document 1, the addition amount of a metal compound (a crosslinking catalyst) to a copolymer containing a hydroxyl group and a carboxyl group is described with (meth) acrylate as a constituent monomer unit. However, There is no description about it. Patent Literature 1 discloses a method of suppressing the viscosity increase rate after the crosslinking agent is blended in the pressure-sensitive adhesive composition, a method of using a reaction retarder, a method of adding a viscosity increasing inhibiting agent, a method of using a crosslinking agent blocking a functional group such as a block isocyanate Method, and the like are exemplified, but there is no specific explanation.

In addition, Patent Document 2 discloses that metal acetylacetonate and acetylacetone having excellent stability and good catalytic activity which do not cause premature curing even when a metal acetylacetonate catalyst such as iron or copper having high activity at low temperature is used, Discloses a method for producing a polyurethane using a catalyst system containing a catalyst.

However, although the weight ratio of metal acetylacetonate to acetylacetone is 2: 1 in the method described in Patent Document 2, the crosslinking reaction can not be temporarily stopped even when this compounding ratio is applied to the production process of an acrylic pressure-sensitive adhesive.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a pressure-sensitive adhesive composition and a surface protective film having a long pot life and a high crosslinking speed without using an organotin compound.

In order to solve the above-mentioned problems, the present invention relates to (A) a copolymerizable monomer group of at least one (meth) acrylic acid ester monomer having an alkyl group having from 4 to 18 carbon atoms, (B) a copolymerizable monomer containing a hydroxyl group 0.1 to 10 parts by weight of a bifunctional or higher functional isocyanate compound (C), 0.001 to 0.5 part by weight of a crosslinking catalyst of a metal chelate compound (D), and 0.1 to 300 parts by weight of a (E) ketoene tautomer compound And (E) / (D) is 70 to 1000 parts by weight based on the total weight of the pressure-sensitive adhesive composition.

Further, it is preferable that the viscosity of the pressure-sensitive adhesive composition after lapse of 8 hours after storage of the pressure-sensitive adhesive composition at 23 DEG C after blending is less than 1.25 times the viscosity immediately after blending.

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.

Of the bifunctional or more isocyanate compounds (C), the bifunctional isocyanate compound is preferably a compound produced by reacting a diisocyanate compound with a diol compound with an acyclic aliphatic isocyanate compound. The diisocyanate compound is preferably an aliphatic diisocyanate and is preferably 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.

Among the isocyanate compounds having two or more functional groups (C) Examples of the trifunctional isocyanate compound include an isocyanurate of a hexamethylene diisocyanate compound, an isocyanurate of an isophorone diisocyanate compound, an adduct of a hexamethylene diisocyanate compound, and an adduct of an isophorone diisocyanate compound , A burette of a hexamethylene diisocyanate compound, 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 xylenylene diisocyanate compound It is preferably at least one selected from the group consisting of a cyanurate, an adduct of a tolylene diisocyanate compound, an adduct of a xylylene diisocyanate compound, and an adduct of a hydrogenated xylylene diisocyanate compound .

It is also preferable that the pressure-sensitive adhesive composition does not contain an organotin compound as the crosslinking catalyst.

It is also preferable that the copolymer is an acrylic polymer containing at least one of a carboxyl group-containing monomer and a nitrogen-containing vinyl monomer not containing a hydroxyl group as another copolymerizable monomer group.

It is also preferable that the gel fraction of the pressure-sensitive adhesive composition after crosslinking is 90 to 100%.

The pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition of the present invention has an adhesive force of 0.05 to 0.2 N / 25 mm at a low speed peeling rate of 0.3 m / min and an adhesive force of 2.0 N / 25 mm Or less.

The present invention also provides an 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.

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 surface 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.

Further, the surface protective film of the present invention can be used as a surface protective film for any one of precision electric / electronic parts selected from the group of precision electric and electronic parts composed of a flexible printed wiring board, a rigid printed wiring board and a transparent conductive film .

According to the present invention, it is possible to provide a pressure-sensitive adhesive composition and a surface protective film having a long pot life and a high crosslinking speed without using an organotin compound.

Further, according to the surface protective film of the present invention, since the organotin compound having no toxicity is not included in the pressure-sensitive adhesive composition, safety is high.

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

The pressure-sensitive adhesive composition of the present invention comprises 100 parts by weight of a copolymer of (A) a copolymerizable monomer containing at least one (meth) acrylic acid ester monomer having an alkyl group of C4 to C18 and a copolymerizable monomer group (B) (C) 0.1 to 10 parts by weight of a bifunctional or higher isocyanate compound, (D) 0.001 to 0.5 parts by weight of a crosslinking catalyst of a metal chelate compound, and (E) 0.1 to 300 parts by weight of a keto- , And the weight ratio of (E) / (D) is 70 to 1000.

The copolymer may be an acrylic polymer containing at least one of a carboxyl group-containing monomer and a nitrogen-containing vinyl monomer not containing a hydroxyl group as another copolymerizable monomer group.

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 98 parts by weight relative to 100 parts by weight of the copolymer.

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.

(B) a copolymerizable monomer containing a hydroxyl group in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the copolymer.

The copolymer may contain at least one or more of a carboxyl group-containing monomer, a nitrogen-containing vinyl monomer not containing a hydroxyl group, and a polyalkylene glycol mono (meth) acrylate monomer as another copolymerizable monomer group.

(Meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethylhexahydrophthalic acid, 2- (Meth) acryloyloxyethyl methacrylate, carboxypolycaprolactone mono (meth) acrylate, 2- (meth) acryloyloxyethylphthalic acid, 2- (Meth) acryloyloxyethyltetrahydrophthalic acid, and at least one compound selected from the group consisting of 2- (meth) acryloyloxyethyltetrahydrophthalic acid.

When the copolymer contains a carboxyl group-containing monomer as the other copolymerizable monomer group, it is preferable that the copolymer contains 0.1 to 1.0 part by weight of a carboxyl group-containing monomer relative to 100 parts by weight of the copolymer. The copolymer may not contain the carboxyl group-containing monomer.

As the polyalkylene glycol mono (meth) acrylic acid ester monomer, any of a 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 a subject copolymer. 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.

It is preferable that the average repeating number of the alkylene oxide constituting the polyalkylene glycol chain of the polyalkylene glycol mono (meth) acrylic acid ester monomer is 3 to 14. The "average number of repeating alkylene oxides" refers to the average number of repeating units of alkylene oxide units in the "polyalkylene glycol chain" portion included in the molecular structure of the polyalkylene glycol mono (meth) acrylate monomer Number.

Examples of the polyalkylene glycol mono (meth) acrylate monomer include polyalkylene glycol mono (meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, ethoxypolyalkylene glycol (meth) And at least one selected from the above.

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 is contained in an amount of 0 to 50 parts by weight based on 100 parts by weight of the copolymer. The copolymer may not contain the polyalkylene glycol mono (meth) acrylate monomer.

Examples of the nitrogen-containing vinyl monomer not containing a hydroxyl group 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 complexes such as N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N- A cyclic nitrogen vinyl compound having a cyclic 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.

It is preferable that the vinyl-containing vinyl monomer containing no hydroxyl group is contained in an amount of 0 to 20 parts by weight relative to 100 parts by weight of the copolymer. The copolymer may not contain a nitrogen-containing vinyl monomer containing no hydroxyl group.

As the bifunctional or higher functional isocyanate compound (C), at least one selected from polyisocyanate compounds having at least two isocyanate (NCO) groups in one molecule may be used. 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 trifunctional or higher isocyanate compound include buret-modified or isocyanurate-modified bifunctional isocyanate compounds (compounds having two NCO groups in one molecule), trimethylolpropane (TMP), tri- or higher-valent polyols such as glycerin And an adduct (polyol modified product) with a compound having at least three OH groups in the molecule).

As the (C) bifunctional or higher isocyanate compound, it is also possible to use only the (C-1) trifunctional isocyanate compound or only the (C-2) bifunctional isocyanate compound. It is also possible to use the (C-1) trifunctional isocyanate compound and the (C-2) bifunctional isocyanate compound in combination.

Examples of the (C-1) trifunctional isocyanate compound used in the present invention include isocyanurate compounds of hexamethylene diisocyanate compounds, isocyanurate compounds of isophorone diisocyanate compounds, and compounds of hexamethylene diisocyanate compounds At least one member selected from the group of (C-1-1) first aliphatic isocyanate compounds consisting of a duct body, 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 xylenediisocyanate compound, an isocyanurate of a hydrogenated xylylene diisocyanate compound, an adduct of a tolylene diisocyanate compound, The adducts, number of isocyanate compounds And at least one selected from the group of (C-1-2) second aromatic isocyanate compounds, which is an adduct of an adduct of aniline isocyanate compound and an adduct of an isocyanurate isocyanate compound. (C-1-1) first aliphatic isocyanate compound group and (C-1-2) second aromatic isocyanate compound group are preferably used in combination. In the present invention, at least one kind selected from the group consisting of (C-1-1) the first aliphatic isocyanate compounds and (C-1-2) the second aromatic isocyanate compound By using at least one selected in combination, it is possible to further improve the balance of the adhesive force in the low-speed peeling area and the high-speed peeling area.

The (C-1) trifunctional isocyanate compound is at least one selected from the group consisting of the above-mentioned (C-1-1) first aliphatic isocyanate compounds, , 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 (C-1-1) the first aliphatic isocyanate compound group and the second aromatic isocyanate compound group (C-1-2) is (C- 1-1) :( C-1-2) in a weight ratio of 10%: 90% to 90%: 10%.

The (C-2) bifunctional isocyanate compound used in the present invention is preferably a non-cyclic aliphatic isocyanate compound, a compound produced by reacting a diisocyanate compound with a diol compound.

For example, the diisocyanate compound may be represented by the formula " HO-Y-OH " (Y is divalent) in the formula " O = C = NXN = C = O " , A compound produced by reacting a diisocyanate compound with a diol compound includes, for example, a compound 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 ". As the bifunctional aliphatic isocyanate compound, a compound wherein n is 0 in the formula (Z) (diisocyanate compound unreacted with respect to the diol compound) may be contained, but it is preferable that the compound contains n as an essential component. 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 radical. 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 divalent aliphatic divalent non-cyclic. 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 (C-1 / C-2) of the (C-1) tribasic isocyanate compound and the (C-2) bifunctional isocyanate compound is preferably 1 to 90. It is preferable that the isocyanate compound (C) having a bifunctionality or higher is 0.1 to 10 parts by weight based on 100 parts by weight of the copolymer.

When the polyisocyanate compound is used as a crosslinking agent, the crosslinking catalyst of the metal chelate compound (D) may be any substance that functions as a catalyst for the reaction (crosslinking reaction) between the copolymer and the crosslinking agent, and an amine compound such as tertiary amine , A metal chelate compound, an organotin compound, an organic lead compound, and an organic zinc compound. In the present invention, a metal chelate compound is used as a crosslinking catalyst.

The metal chelate compound is a compound in which at least one dorsal ligand L is bonded to the central metal atom M. The metal chelate compound may or may not have at least one monocyclic ligand X bonded to the metal atom M. For example, when the chemical formula of a metal chelate compound having one metal atom M is represented by M (L) _m (X) _n , _m? 1, _n ? When m is 2 or more, m Ls may be the same ligand or different ligands. When n is 2 or more, n Xs may be the same ligand or different ligands.

Examples of the metal atom M include Fe, Ni, Mn, Cr, V, Ti, Ru, Zn, Al, Zr and Sn.

Examples of the polycondensate L include β-keto esters such as methyl acetoate, ethyl acetoate, octyl acetoate, oleyl acetoate, lauryl acetoacetate, and stearyl acetoate, acetyl acetone (also called 2,4-pentanedione) , 2,4-hexanedione, and benzoyl acetone. These are keto enol tautomeric compounds, and for the polydentate ligands L, enol may be a deprotonated enolate (for example, acetylacetonate).

Examples of the monocyclic ligand X include acyloxys such as a halogen atom such as a chlorine atom and a bromine atom, a pentanoyl group, a hexanoyl group, a 2-ethylhexanoyl group, an octanoyl group, a nonanoyl group, a decanoyl group, a dodecanoyl group, A methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, and a butoxy group.

Specific examples of the metal chelate compound include tris (2,4-pentanedionate) iron (III), iron trisacetylacetonate, titanium trisacetylacetonate, ruthenium trisacetylacetonate, zinc bisacetylacetonate, aluminum tris (2,4-hexanedionate) iron (III), bis (2,4-hexanedionate) zinc, tris (2,4-hexanedionate) titanium, Tris (2,4-hexanedionate) aluminum, tetrakis (2,4-hexanedionate) zirconium, and the like.

Examples of the organotin compounds include dialkyltin oxide, dialkyltin fatty acid salts, and stannous primary fatty acid salts. Conventionally, dibutyltin compounds have been widely used. However, recently, toxicity problems of organotin compounds have been pointed out. In particular, tributyltin (TBT) contained in dibutyltin compounds is also considered as an endocrine disruptor. From the viewpoint of safety, long-chain alkyltin compounds such as dioctyltin compounds are preferable. Specific organic tin compounds include dioctyltin oxide, dioctyltin dilaurate and the like. Although Sn compounds may be used as a matter of fact, in the future, it is desirable to use metal chelate compounds such as Al, Ti, Fe, etc., which are more safe than Sn, in view of the trend of using a material having higher safety desirable.

The metal chelate compound in the pressure-sensitive adhesive composition according to the present invention is preferably at least one selected from the group consisting of an aluminum chelate compound, a titanium chelate compound and an iron chelate compound.

The crosslinking catalyst of the metal chelate compound (D) is preferably contained in an amount of 0.001 to 0.5 parts by weight based on 100 parts by weight of the copolymer.

Examples of the ketone-enol tautomer compound (E) include β-keto esters such as methyl acetoate, ethyl acetoate, octyl acetoate, oleyl acetoate, lauryl acetoacetate and stearyl acetoate, acetyl acetone, , 4-hexanedione, and benzoyl acetone. In these pressure-sensitive adhesive compositions using a polyisocyanate compound as a cross-linking agent, blocking the isocyanate group of the cross-linking agent inhibits the viscosity increase and gelation, which are excessive in the pressure-sensitive adhesive composition after the cross-linking agent is blended, and prolongs the pot life of the pressure- .

It is preferable that the (E) ketoene tautomer compound is contained in an amount of 0.1 to 300 parts by weight based on 100 parts by weight of the copolymer.

(E) Keto enol tautomer compound (D) has an effect of inhibiting crosslinking as opposed to (D) a crosslinking catalyst of a metal chelate compound, and (D) It is preferable to appropriately set the ratio of the isomeric compound. (E) / (D) of the crosslinking catalyst of the (E) ketoene aliphatic isomer compound / (D) metal chelate compound is preferably high in order to lengthen the pot life of the pressure-sensitive adhesive composition and improve the storage stability . The value of (E) / (D) is preferably in the range of 70 to 1000, more preferably 70 to 800, and most preferably 80 to 600.

More preferably, the pressure-sensitive adhesive composition having a longer pot life according to the present invention is preferably stored at 23 占 폚 after blending the pressure-sensitive adhesive composition, and the viscosity of the pressure-sensitive adhesive composition after elapse of 8 hours is preferably 1.25 times or less of the viscosity immediately after the blending . This makes it possible to obtain a pressure-sensitive adhesive composition in which viscosity increase after blending is suppressed.

The pressure-sensitive adhesive composition of the present invention may contain, as additives, additives such as antistatic agents, polyether siloxane compounds and other conventional antioxidants.

As the antistatic agent, there may be mentioned an antistatic agent contained in the pressure-sensitive adhesive composition and an antistatic agent copolymerized in the copolymer. It is preferable that the antistatic agent is contained in an amount of 0.05 to 5.0 parts by weight based on 100 parts by weight of the copolymer.

The antistatic agent is preferably an ionic compound and / or an acryloyl group-containing ionic compound which is a solid at a temperature of 25 ° C and a melting point of 25 ° C to 50 ° C. Since these antistatic agents have a low melting point and also have a long chain alkyl group, it is presumed that the affinity with an acrylic copolymer is high.

The ionic compound having a melting point of 25 to 50 占 폚 includes 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, pyrazolium cation, pyrrolidinium (PF ₆ ^- ), thiocyanate salt (SCN ^- ), alkylbenzenesulfonic acid salt ((S) ^- ), and the like. RC ₆ H ₄ SO ₃ ^- ), perchlorate (ClO ₄ ^- ), tetrafluoroborate (BF ₄ ^- ), bis (fluorosulfonyl) imide salt (FSI), bis (trifluoromethanesulfonyl) imide salt (TFSI), trifluoromethanesulfonic acid salt (TF), and the like. It is preferably solid at ordinary temperature (for example, 25 占 폚), and a melting point of 25 to 50 占 폚 can be obtained depending on the choice of the chain length of the alkyl group, the position and number of substituent groups, and the like. The cation is preferably a quaternary ammonium onium cation, a quaternary pyridinium cation such as 1-alkyl pyridinium (the carbon atom at 2-6 may have a substituent or may be unsubstituted), or a 1,3-pyridinium cation such as 1,3 - quaternary imidazolium cation such as dialkyl imidazolium (the carbon atom at the 2, 4 or 5 position may have a substituent or may be unsubstituted), quaternary ammonium cation such as tetraalkylammonium, etc. .

The ionic compound having a melting point of 25 to 50 占 폚 is preferably contained in an amount of 0.05 to 5 parts by weight based on 100 parts by weight of the copolymer.

As the acryloyl group-containing ionic compound, an ionic compound having a cation and an anion, wherein the cation is a (meth) acryloyloxyalkyltrialkylammonium [R ₃ N ⁺ -C _n H _2n -OCOCQ = CH ₂ , Q = H or CH _3, R = alkyl, such as (meth) and group-containing cation with acrylic, anion is hexafluorophosphate phosphate (PF ₆ ^-), thiocyanate (SCN ^-), organic acid salts (RSO ₃ ^- ), Inorganic or organic anions such as 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 contains the already deuyeom, 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 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 antistatic agent include, but are not particularly limited to, specific examples of the ionic compound having a melting point of 25 to 50 캜 include 1-octylpyridinium hexafluorophosphate, 1-nonylpyridinium hexafluorophosphate, 2- Methyl-1-dodecylpyridinium hexafluorophosphate, 1-octylpyridinium dodecylbenzenesulfonate, 1-dodecylpyridinium thiocyanate, 1-dodecylpyridinium dodecylbenzenesulfonate, 4-methyl- Octylpyridinium hexafluorophosphate, quaternary ammonium salts of trifluoromethanesulfonic acid, and the like. Specific examples of the acryloyl group-containing ionic compound include dimethylaminomethyl (meth) acrylate hexafluorophosphate methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ = CH ₂ PF ₆ ^- , where Q = H or CH _3], dimethylaminoethyl (meth) (methanesulfonyl trifluoromethanesulfonyl) imide methyl salt acrylate, bis ^{_{[(CH 3) 3 N +}} (CH 2) 2 OCOCQ = CH 2 · (CF 3 SO _{2) 2} N ^-, stage, Q = H or CH _3], dimethylaminomethyl methacrylate, bis (fluoro sulfonyl) imide methyl salt ^{_{[(CH 3) 3 N +}} CH 2 OCOCQ = CH 2 · (FSO ₂ ) ₂ N ^- , with Q = H or CH ₃ ].

The polyether-modified siloxane compound is a polyether, and siloxane compounds having, typical siloxane unit [-SiR ¹ ₂ -O-] In addition, polyether siloxane unit groups ^{[-SiR 1 (R 2 O (} R 3 O) _n having 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 polyoxyethylene group [(C ₂ H ₄ O) _n ] and 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 15. It is preferable that the polyether-modified siloxane compound is contained in an amount of 0.01 to 1.0 part by weight based on 100 parts by weight of the copolymer. More preferably 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 with 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.

Examples of the antioxidant include a hindered phenol-based antioxidant, a polyphenol compound, and a tocopherol-based compound. Among them, a tocopherol compound is preferable. The tocopherol-based compounds are generally vitamin E and are also natural-derived chemicals. As a result, there are few adverse effects on the human body, high handling safety, and environment friendliness. Further, since it is an oil-soluble and liquid at room temperature, it is also excellent in compatibility with a pressure-sensitive adhesive composition and in precipitation resistance. By adding the tocopherol-based compound as the antioxidant, the storage stability of the pressure-sensitive adhesive is improved, so that the pot life of the pressure-sensitive adhesive composition containing the curing agent is improved.

The tocopherol-based compound used in the present invention is preferably a compound having no ferulic hydroxyl group in the tocopherol such as ester or the like in view of its being used in combination with the pressure-sensitive adhesive composition (it is not metabolized as in the human body) For example, tocopherol or tocotrienol. It is known that tocopherol and tocotrienol have a distinction such as a natural compound (d-form), a non-natural compound (1-form) and a racemic mixture (dl-form). Natural compounds (d-form) and racemates (dl-form) are preferred because they are also used as food additives and the like.

Specific tocopherol-based compounds include d-alpha-tocopherol, dl- alpha -tocopherol, dl-beta -tocopherol, dl-beta -tocopherol, d- tocotrienol, dl-a-tocotrienol, dl-a-tocotrienol, dl-a-tocotrienol, dl-a-tocotrienol, dl- - at least one selected from the group consisting of tocotrienol. Two or more kinds of tocopherol compounds may be used in combination. As a food additive, what is termed "mixed tocopherol" is a mixture containing d-α-tocopherol, d-β-tocopherol, d-γ-tocopherol and d-δ-tocopherol as the main components, Tocotrienol, d-β-tocotrienol, d-γ-tocotrienol and d-δ-tocotrienol.

When the pressure-sensitive adhesive composition of the present invention contains a tocopherol compound, it is preferable that the tocopherol compound is contained in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the copolymer.

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 catalyst, a plasticizer, a filler, , An antioxidant, and an antioxidant may be appropriately added. These 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) Can be synthesized by copolymerizing monomers. 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.

In addition, the copolymer may include at least one of a carboxyl group-containing monomer and a nitrogen-containing vinyl monomer not containing a hydroxyl group as another copolymerizable monomer group.

The pressure-sensitive adhesive composition of the present invention can be prepared by compounding the above-mentioned copolymer with (C) an isocyanate compound having two or more functional groups, (D) a crosslinking catalyst of a metal chelate compound, (E) a ketoene tautomer compound and further optionally an optional additive .

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 copolymer is preferably 8.0 or less, more 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 indicating the content of the acid, and represents 1 g of the polymer containing a carboxyl group, in mg of potassium hydroxide necessary for neutralization.

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 0.2 N / 25 mm at a low speed peeling rate of 0.3 m / min and an adhesive force of 2.0 N / 25 mm or less at a high peeling rate 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. In addition, in order to reattach it, an excessive force is not necessary even once the surface protective film is peeled, and it is easy to peel off from the adherend.

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 90 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 contains the components (A) to (E) in a well-balanced manner, the pot life is long and the crosslinking speed is high without using the organotin compound. Therefore, the surface protective film of the present invention can be used as a surface protective film of a polarizing plate or as a precision electric / electronic part selected from the group of precision electric and electronic parts comprising a flexible printed wiring board, a rigid printed wiring board and a transparent conductive film Can be suitably used as a surface protective film for use.

In the adhesive film and the surface protective film according to the present invention, a polyester film or the like can be used as the base material of the resin film and the release film (separator) for protecting the pressure-sensitive adhesive layer.

The resin film may be subjected to an antifouling treatment with a silicone, a fluorine-based releasing agent, a coating agent, fine silica particles or the like, or an antistatic treatment by application or incorporation of an antistatic agent on the surface opposite to the side where the pressure-

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

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 and 3.5 parts by weight of 8-hydroxyoctyl acrylate were added to the reactor. 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 sample for measuring the acid value described later.

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

The same procedures as in the acrylic copolymer solution (1) used in Example 1 were carried out except that the monomers were changed as shown in Table 1 (A), (B) and (I) Acrylic copolymer solutions used in Comparative Examples 1 to 3 were obtained.

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

[Example 1]

To the acrylic copolymer solution (1) of Example 1 thus prepared, 6.0 parts by weight of acetylacetone was added and stirred. Then, 1.5 parts by weight of Coronate HX (isocyanurate of hexamethylene diisocyanate compound) 0.05 part by weight of tris (2,4-pentanedionate) iron (III) was 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 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 6 and Comparative Examples 1 to 3]

The surface protective films of Examples 2 to 6 and Comparative Examples 1 to 3 were formed in the same manner as in the surface protective film of Example 1 except that the additives were changed as shown in Table 1 (C) to (E) .

Table 1 shows the numerical values of the parts by weight obtained by taking the total of the group (A) as 100 parts by weight in parentheses. The values of the ratios of (E) / (D) are shown in Table 2. Table 3 shows the compound names of the weak symbols of the respective components used in Table 1. D-140N is a trade name of Mitsui Chemicals, Inc., Dyuranate (registered trademark) D101 is a trade name of Asahi Kasei Co., Ltd., Lt; / RTI >

<Test Method and Evaluation>

The surface protective films of Examples 1 to 6 and Comparative Examples 1 to 3 were aged for 7 days under an atmosphere of 23 ° C and 50% RH, and then a release film (PET resin coated with silicone resin) was peeled off to form a pressure- Lt; / RTI &gt; 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 allowed to stand for 12 hours as a measurement sample of the adhesive force.

<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 peel strength measured as the adhesive force.

<Portlife>

(C) ~ (E) measuring the viscosity η ₀ (initial viscosity) of the adhesive composition immediately after combination of additives, and the viscosity of the pressure-sensitive adhesive composition after being allowed to stand again 23 ℃ × 8 hours of pressure-sensitive adhesive composition to the closed state η ₁ ( Viscosity after 8 hours) was measured. The ratio of the value of eta ₁ , that is, the ratio of eta ₁ / eta _{0 to} the value of eta ₀ as an index of pot life was obtained. The evaluation target standard was evaluated as &quot;?&Quot; when the viscosity after 8 hours was less than 1.25 times the initial viscosity, &quot;?&Quot; when the viscosity was 1.25 times or more and 1.50 times or less, Respectively.

Table 4 shows the evaluation results.

The surface protective films of Examples 1 to 6 had an adhesive force of 0.05 to 0.2 N / 25 mm at a low speed peeling rate of 0.3 m / min and an adhesive force of 2.0 N / 25 mm or less at a high peeling rate of 30 m / min, Was long enough.

That is, at a low speed peeling speed and a high speed peeling speed, the balance of the adhesive force was excellent, the pot life was long, and the characteristics as the surface protective film were excellent.

Further, according to the surface protecting films of Examples 1 to 6, since the organotin compound is not contained in the pressure-sensitive adhesive composition, safety is high.

The surface protective film of Comparative Example 1 had neither the (C) bifunctional or higher isocyanate compound serving as a crosslinking agent, nor the adhesive force at a low rate of peeling at 0.3 m / min and at a high rate of peeling of 30 m / min.

In the surface protective film of Comparative Example 2, the port life was short because the ratio of the (E) ketoene tautomeric compound to the crosslinking catalyst of the (D) metal chelate compound was small.

Since the ratio of the (E) ketoene tautomeric compound (E) to the crosslinking catalyst of the metal chelate compound (D) of the surface protective film of Comparative Example 3 was small, the port life was excessively shortened and crosslinking proceeded before application. I could not.

As described above, the surface protective films of Comparative Examples 1 to 3 were not able to simultaneously satisfy all of the required performances such as excellent balance of adhesive force and long pot life at low and high peeling rates.

Claims (3)

1. A surface protective film comprising a pressure-sensitive adhesive layer formed by crosslinking an acrylic polymer and a pressure-sensitive adhesive composition containing a crosslinking agent on one surface of a resin film,
(A) at least one (meth) acrylate monomer having an alkyl group of C4 to C18 in the alkyl group and (B) at least one copolymerizable monomer containing a hydroxyl group as a copolymerizable monomer group And,
Wherein the pressure-sensitive adhesive composition comprises (C) 0.1 to 10 parts by weight of an isocyanate compound having two or more functional groups, (D) 0.001 to 0.5 parts by weight of a crosslinking catalyst of a metal chelate compound, (E) / (D) is 80 to 600 parts by weight,
Wherein the metal chelate compound (D) is at least one member selected from the group consisting of an aluminum chelate compound, a titanium chelate compound, and an iron chelate compound,
Wherein the pressure-sensitive adhesive layer has an adhesive force of 0.05 to 0.2 N / 25 mm at a low speed peeling speed of 0.3 m / min and an adhesive force of 2.0 N / 25 mm or less at a high speed peeling speed of 30 m / min. The method according to claim 1,
Wherein the copolymer is an acryl-based polymer containing at least one of a carboxyl group-containing monomer and a nitrogen-containing vinyl monomer not containing a hydroxyl group as the other copolymerizable monomer group. 3. The method according to claim 1 or 2,
A surface protective film for use as a surface protective film of a polarizing plate, or a surface protective film of a precision electric / electronic component selected from the group consisting of a flexible printed wiring board, a rigid printed wiring board, .