Adhesive composition

Abstract

The present invention provides an adhesive composition, adhesive layer, adhesive film, and surface protective film that possess antistatic properties, have an excellent balance of adhesive strength at both low and high peeling speeds, have a long pot life, and exhibit excellent durability and reworkability. [Solution] An acrylic polymer comprising (A) a (meth)acrylic acid ester monomer having C4 to C18 C atoms in the alkyl group, (B) a monomer containing a hydroxyl group, (C) a monomer containing a carboxyl group, (D) a polyalkylene glycol mono(meth)acrylic acid ester monomer, (E) a nitrogen-containing vinyl monomer or an alkyl(meth)acrylate monomer containing an alkoxy group, (F) a bifunctional or more isocyanate compound as a crosslinking agent, (J) a polyether-modified siloxane compound, (K) an antioxidant, and (I) an ionic compound having a melting point of 25 to 50°C as an antistatic agent, and / or copolymerized with an acryloyl group-containing ionic compound.

Description

[Technical Field]

[0001] The present invention relates to an adhesive composition, an adhesive film, and a surface protection film. More specifically, the present invention relates to an adhesive composition, an adhesive film, and a surface protection film for polarizing plates that have antistatic properties, excellent balance of adhesive strength at low and high peeling speeds, a long pot life, and excellent durability and reworkability. [Background technology]

[0002] For optical applications, acrylic adhesives are preferably used due to their excellent transparency. These adhesives consist of copolymers made by copolymerizing alkyl (meth)acrylate as the main component with acrylic monomers having functional groups such as hydroxyl and carboxyl groups. Furthermore, it is necessary that the various physical properties of the adhesive, such as its adhesive strength, are appropriately adjusted. In particular, adhesives for surface protection films require an excellent balance of adhesive strength at both low and high peeling speeds, suitable for bonding surface protection films using automated laminating equipment, to accommodate factory production processes. In addition to this balance of adhesive strength, adhesives with a long pot life, excellent durability, reworkability, and antistatic properties are also required.

[0003] The various physical properties of such adhesives are adjusted by using isocyanate-based crosslinking agents, epoxy-based crosslinking agents, etc., which react with functional groups such as hydroxyl groups and carboxyl groups contained in acrylic adhesives made of copolymers, thereby controlling tackiness, cohesiveness, and other properties.

[0004] Conventionally, isocyanate-based crosslinking agents have been commonly used as crosslinking agents for acrylic adhesives. Furthermore, in crosslinking reactions using isocyanate-based crosslinking agents, metal chelates are often used as catalysts to promote the crosslinking reaction. Generally, organotin compounds such as dibutyltin dilaurate were used as catalysts for crosslinking reactions due to their excellent reaction rate. However, dibutyltin compounds are avoided because they exhibit harmful toxicity. Therefore, there has been a need for an inexpensive crosslinking catalyst with excellent reaction rate in crosslinking reactions, which can serve as an alternative to dibutyltin compounds used in combination with isocyanate-based crosslinking agents, but such a catalyst has been difficult to find.

[0005] In this context, Patent Document 1 discloses that among metal chelates, iron chelates are preferred as crosslinking catalysts used in combination with isocyanate-based crosslinking agents, and tris(acetylacetonate)iron is particularly preferred due to its excellent catalytic activity.

[0006] Incidentally, acrylic adhesive compositions containing a crosslinking catalyst undergo a gradual crosslinking reaction even when left at room temperature. Therefore, in the industrial production of adhesives, a crosslinking catalyst and a reaction retarder are generally used in combination to halt the crosslinking reaction after the raw materials for the adhesive composition have been blended, until the time when the crosslinking reaction is to be initiated. Regarding the combined use of this crosslinking catalyst and reaction retarder, Patent Document 2 discloses a method for producing polyurethane, which involves using a reaction urethane mixture containing a catalyst system comprising a mixture of at least one metal acetylacetonate and acetylacetone, wherein the weight ratio of the metal acetylacetonate to the acetylacetone is 2:1. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2011-001440 [Patent Document 2] Japanese Patent Publication No. 2008-285681 [Overview of the project] [Problems that the invention aims to solve]

[0008] In the adhesive composition described in Patent Document 1, the amount of a metal compound (crosslinking catalyst) added to a copolymer containing (meth)acrylate as a constituent monomer unit and having a hydroxyl group and a carboxyl group is shown, but there is no description about the amount of a crosslinking retarder added. Further, Patent Document 1 mentions methods such as using a reaction retarder, adding a viscosity increase suppressing solvent, using a crosslinking agent having a blocked functional group such as blocked isocyanate, etc. as methods for suppressing the viscosity increase rate after blending a crosslinking agent into the adhesive composition, but there is no specific explanation.

[0009] Further, Patent Document 2 discloses a method for producing a polyurethane using a catalyst system containing metal acetylacetonate and acetylacetone, which has excellent stability and good catalytic activity and does not cause early curing even when using a metal acetylacetonate catalyst such as iron or copper that is highly active at low temperatures. However, in the method described in Patent Document 2, although the weight ratio of metal acetylacetonate to acetylacetone is 2:1, even when this blending ratio is applied to the production process of an acrylic adhesive, the crosslinking reaction could not be temporarily stopped.

[0010] In view of the above circumstances, the present invention has been made, and without using an organotin compound, it has antistatic performance, has an excellent balance of adhesive force at a low peeling speed and a high peeling speed, further has a long pot life, and provides an adhesive composition for a surface protection film of a polarizing plate, an adhesive film, and a surface protection film that are excellent in durability and reworkability.

Means for Solving the Problems

[0011] In order to solve the above problems, the present invention is an adhesive film formed by forming an adhesive layer on one or both sides of a resin film and laminating a release film having a silicone-based release agent layer on the adhesive layer, where the adhesive layer is formed by crosslinking an adhesive composition containing an acrylic polymer and a crosslinking agent. The acrylic polymer is used in proportion to 100 parts by weight of the total amount of the acrylic polymers. (A) 50 to 95 parts by weight of at least one (meth)acrylic acid ester monomer having C4 to C18 in the alkyl group, (B) 0.1 to 10 parts by weight of copolymerizable monomer containing a hydroxyl group, (C) 0.1 to 1.0 parts by weight of a copolymerizable monomer containing a carboxyl group, The copolymerizable monomer group consists of (D) 0 to 50 parts by weight of polyalkylene glycol mono(meth)acrylate or polyalkylene glycol alkyl ether (meth)acrylate, and (E) 0 to 20 parts by weight of nitrogen-containing vinyl monomer that does not contain hydroxyl groups or alkyl(meth)acrylate monomer that does not contain hydroxyl groups, and at least one copolymerizable monomer selected from the copolymerizable monomer group, It consists of an acrylic polymer copolymer with an acid value of 0.01 to 8.0 obtained by copolymerizing the following: The copolymerizable monomer containing a hydroxyl group (B) is at least one selected from the group of compounds consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxyethyl (meth)acrylamide. The adhesive composition contains, per 100 parts by weight of the total acrylic polymer, 0.1 to 10 parts by weight of (F) a bifunctional or more isocyanate compound as the crosslinking agent, 0.001 to 0.5 parts by weight of (G) a metal chelate compound crosslinking catalyst, and 0.1 to 200 parts by weight of (H) a ketoenol tautomer compound, and the weight ratio of the (H) ketoenol tautomer compound to the (G) metal chelate compound crosslinking catalyst (H) / (G) is 1 to 700. The adhesive composition further comprises (I) an antistatic agent, (J) a polyether-modified siloxane compound, and (K) an antioxidant. The present invention provides an adhesive film characterized in that the (K) antioxidant is a tocopherol-based antioxidant, and the tocopherol-based compound used as the antioxidant is at least one selected from the group of compounds consisting of d-α-tocopherol, dl-α-tocopherol, d-β-tocopherol, dl-β-tocopherol, d-γ-tocopherol, dl-γ-tocopherol, d-δ-tocopherol, dl-δ-tocopherol, d-α-tocotrienol, dl-α-tocotrienol, d-β-tocotrienol, dl-β-tocotrienol, d-γ-tocotrienol, dl-γ-tocotrienol, dl-δ-tocotrienol, and dl-δ-tocotrienol.

[0012] Furthermore, with respect to 100 parts by weight of the total amount of the acrylic polymer of the copolymer, The aforementioned acrylic polymer (A) 50 to 95 parts by weight of (meth)acrylic acid ester monomer having C4 to C18 carbon atoms in the alkyl group, (B) 0.1 to 10 parts by weight of copolymerizable monomer containing a hydroxyl group, (C) 0.1 to 1.0 parts by weight of copolymerizable monomer containing a carboxyl group, (D) 0 to 50 parts by weight of polyalkylene glycol mono(meth)acrylate or polyalkylene glycol alkyl ether(meth)acrylate, The above-mentioned (E) contains 0 to 20 parts by weight of a nitrogen-containing vinyl monomer that does not contain hydroxyl groups or an alkyl (meth)acrylate monomer that does not contain hydroxyl groups, The adhesive composition is (F) 0.1 to 10 parts by weight of a two- or more functional isocyanate compound, 0.001 to 0.5 parts by weight of the (G) crosslinking catalyst of the metal chelate compound, The (H) ketoenol tautomer compound is present in 0.1 to 200 parts by weight, and the weight ratio (H) / (G) of the (H) ketoenol tautomer compound / (G) metal chelate compound crosslinking catalyst is 1 to 700, and further, The (I) antistatic agent is 0.05 to 5.0 parts by weight of the total of the antistatic agent contained in the adhesive composition and the antistatic agent copolymerized in the copolymer, 0.01 to 1.0 parts by weight of the (J) polyether-modified siloxane compound, The (K) antioxidant comprises 0.01 to 5 parts by weight of a tocopherol-based antioxidant, Preferably, the tocopherol-based compound used as the antioxidant is at least one selected from the group of compounds consisting of d-α-tocopherol, dl-α-tocopherol, d-β-tocopherol, dl-β-tocopherol, d-γ-tocopherol, dl-γ-tocopherol, d-δ-tocopherol, dl-δ-tocopherol, d-α-tocotrienol, dl-α-tocotrienol, d-β-tocotrienol, dl-β-tocotrienol, d-γ-tocotrienol, dl-γ-tocotrienol, dl-δ-tocotrienol, and dl-δ-tocotrienol.

[0013] Furthermore, the copolymerizable monomer containing the (C) carboxyl group is at least one selected from the group of compounds consisting of (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl maleic acid, carboxypolycaprolactone mono(meth)acrylate, and 2-(meth)acryloyloxyethyl tetrahydrophthalic acid. The (D) polyalkylene glycol mono(meth)acrylate or polyalkylene glycol alkyl ether (meth)acrylate is preferably at least one selected from polyalkylene glycol mono(meth)acrylate, polyalkylene glycol methyl ether (meth)acrylate, and polyalkylene glycol ethyl ether (meth)acrylate, with an average number of repeating alkylene oxides constituting the polyalkylene glycol chain being 3 to 14.

[0014] Furthermore, it is preferable that the acrylic polymer contains at least one of the following copolymerizable monomers: (E) nitrogen-containing vinyl monomers that do not contain hydroxyl groups or alkyl (meth)acrylate monomers that contain alkoxy groups.

[0015] Furthermore, as the (F) isocyanate compound with two or more functions, the bifunctional isocyanate compound is preferably an acyclic aliphatic isocyanate compound, which is a compound produced by reacting a diisocyanate compound with a diol compound. The diisocyanate compound is preferably an aliphatic diisocyanate, which is one selected from the group of compounds consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate. Furthermore, it is preferable that the diol compound is one selected from the group of compounds consisting of 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxypivalate, polyethylene glycol, and polypropylene glycol. Furthermore, as the (F) isocyanate compound with two or more functions, it is preferable that the trifunctional isocyanate compound be at least one selected from the group of compounds consisting of isocyanurate of hexamethylene diisocyanate compounds, isocyanurate of isophorone diisocyanate compounds, adduct of hexamethylene diisocyanate compounds, adduct of isophorone diisocyanate compounds, burette of hexamethylene diisocyanate compounds, burette of isophorone diisocyanate compounds, isocyanurate of tolylene diisocyanate compounds, isocyanurate of xylylene diisocyanate compounds, isocyanurate of hydrogenated xylylene diisocyanate compounds, adduct of tolylene diisocyanate compounds, adduct of xylylene diisocyanate compounds, and adduct of hydrogenated xylylene diisocyanate compounds.

[0016] Furthermore, it is preferable that the antistatic agent (I) is an ionic compound having a melting point of 25 to 50°C, and / or an acryloyl group-containing ionic compound copolymerized in the copolymer at a concentration of 0.1 to 5.0% by weight per 100 parts by weight of the copolymer.

[0017] Furthermore, it is preferable that the HLB value of the (J) polyether-modified siloxane compound is 7 to 15.

[0018] Furthermore, it is preferable that the crosslinking catalyst in the adhesive composition does not contain organotin compounds.

[0019] Furthermore, it is preferable that the adhesive layer formed by crosslinking the adhesive composition has an adhesive strength of 0.05 to 0.1 N / 25 mm at a low peeling speed of 0.3 m / min, and an adhesive strength of 1.0 N / 25 mm or less at a high peeling speed of 30 m / min.

[0020] Furthermore, the surface resistivity of the adhesive layer formed by crosslinking the adhesive composition is 9.0 × 10 +11 It is preferable that the impedance is Ω / □ or less and the stripping band voltage is ±0 to 0.5kV.

[0021] Furthermore, the present invention provides a surface protection film characterized by being made using the adhesive film.

[0022] Furthermore, the surface protection film of the present invention can be used as a surface protection film for polarizing plates.

[0023] Furthermore, it is preferable that the surface protective film of the present invention has an antistatic and antifouling treatment applied to the side of the resin film opposite to the side on which the adhesive layer is formed. [Effects of the Invention]

[0024] According to the present invention, all the performance requirements for the adhesive layer of a surface protective film, which could not be solved by conventional technology, can be satisfied without using organotin compounds, and furthermore, excellent antistatic performance can be obtained and the occurrence of adhesive residue can be prevented. Specifically, it is possible to reduce the amount of antistatic agent added while maintaining excellent antistatic performance, and the performance in preventing the occurrence of adhesive residue can be further improved. [Modes for carrying out the invention]

[0025] The present invention will be described below based on preferred embodiments. The adhesive composition of the present invention comprises, as its main component, (A) at least one (meth)acrylic acid ester monomer having C4 to C18 C in its alkyl group, and as a copolymerizable monomer group, (B) copolymerizable monomers containing a hydroxyl group, (C) copolymerizable monomers containing a carboxyl group, (D) polyalkylene glycol mono(meth)acrylic acid ester monomer, and (E) nitrogen-containing vinyl monomer or alkoxy group-containing alkyl(meth)acrylate monomer that does not contain a hydroxyl group. The acrylic polymer is a copolymer having an acid value of 0.01 to 8.0 and comprises at least one monomer selected from a group of combinatable monomers, and is further characterized by containing (F) a bifunctional or more isocyanate compound, (G) a crosslinking catalyst for a metal chelate compound, (H) a ketoenol tautomer compound, (I) an ionic compound having a melting point of 25 to 50°C as an antistatic agent, and / or an acryloyl group-containing ionic compound, (J) a polyether-modified siloxane compound, and (K) an antioxidant. Furthermore, it is preferable that, per 100 parts by weight of the total acrylic polymer copolymer, the acrylic polymer contains: (A) 50 to 95 parts by weight of (meth)acrylic acid ester monomer having C4 to C18 C atoms in the alkyl group; (B) 0.1 to 10 parts by weight of copolymerizable monomer containing a hydroxyl group; (C) 0.1 to 1.0 part by weight of copolymerizable monomer containing a carboxyl group; (D) 0 to 50 parts by weight of polyalkylene glycol mono(meth)acrylic acid ester monomer; and (E) 0 to 20 parts by weight of nitrogen-containing vinyl monomer or alkyl(meth)acrylate monomer containing an alkoxy group that does not contain a hydroxyl group. Furthermore, it is preferable that, per 100 parts by weight of the total acrylic polymer copolymer, the adhesive composition contains (F) 0.1 to 10 parts by weight of a bifunctional or more isocyanate compound, (G) 0.001 to 0.5 parts by weight of a crosslinking catalyst of a metal chelate compound, and (H) 0.1 to 200 parts by weight of a ketoenol tautomer compound, and the weight ratio of the (H) ketoenol tautomer compound to (G) crosslinking catalyst of the metal chelate compound (H) / (G) is 1 to 700, and further, (I) as an antistatic agent, the total of the antistatic agent contained in the adhesive composition and the antistatic agent copolymerized in the copolymer is 0.05 to 5.0 parts by weight, (J) 0.01 to 1.0 part by weight of a polyether-modified siloxane compound, and (K) as an antioxidant, 0.01 to 5 parts by weight of a tocopherol-based antioxidant.

[0026] (A) Examples of (meth)acrylic acid ester monomers with C4 to C18 alkyl groups include butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, and undecyl Examples include (meth)acrylate, dodecyl(meth)acrylate, tridecyl(meth)acrylate, tetradecyl(meth)acrylate, pentadecyl(meth)acrylate, hexadecyl(meth)acrylate, heptadecyl(meth)acrylate, octadecyl(meth)acrylate, myristyl(meth)acrylate, isomiristyl(meth)acrylate, cetyl(meth)acrylate, isocetyl(meth)acrylate, stearyl(meth)acrylate, isostearyl(meth)acrylate, and others. When the total amount of the acrylic polymer in the copolymer is 100 parts by weight, it is preferable that (A) (meth)acrylic acid ester monomers having C4 to C18 C atoms in the alkyl group are contained in a proportion of 50 to 95 parts by weight.

[0027] (B) Examples of copolymerizable monomers containing hydroxyl groups include hydroxyalkyl (meth)acrylates such as 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate, as well as hydroxyl group-containing (meth)acrylamides such as N-hydroxy (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxyethyl (meth)acrylamide. Preferably, it is at least one compound selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxyethyl (meth)acrylamide. When the total amount of the acrylic polymer copolymer is 100 parts by weight, it is preferable that the copolymerizable monomer containing the hydroxyl group (B) is contained in a proportion of 0.1 to 10 parts by weight.

[0028] (C) Preferably, the copolymerizable monomer containing a carboxyl group is at least one selected from the group of compounds consisting of (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl maleic acid, carboxypolycaprolactone mono(meth)acrylate, and 2-(meth)acryloyloxyethyl tetrahydrophthalic acid. When the total amount of the acrylic polymer copolymer is 100 parts by weight, it is preferable that the copolymerizable monomer containing the (C) carboxyl group is contained in a proportion of 0.1 to 1.0 parts by weight. In the adhesive layer according to the present invention, it is preferable that the copolymerizable monomer containing the (C) carboxyl group in the adhesive composition is contained within a range such that the acid value of the copolymer is 0.01 to 8.0, as will be described later.

[0029] (D) The polyalkylene glycol mono(meth)acrylic acid ester monomer can be any compound in which one of the multiple hydroxyl groups of the polyalkylene glycol is esterified as a (meth)acrylic acid ester. Since the (meth)acrylic acid ester group is a polymerizable group, it can be copolymerized with the main polymer. The other hydroxyl groups may remain as OH groups, or they may be alkyl ethers such as methyl ether or ethyl ether, or saturated carboxylic acid esters such as acetate esters, etc. The alkylene groups in polyalkylene glycol include, but are not limited to, ethylene groups, propylene groups, and butylene groups. The polyalkylene glycol may be a copolymer of two or more polyalkylene glycols, such as polyethylene glycol, polypropylene glycol, and polybutylene glycol. Examples of polyalkylene glycol copolymers include polyethylene glycol-polypropylene glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, and polyethylene glycol-polypropylene glycol-polybutylene glycol, and the copolymer may be a block copolymer or a random copolymer. (D) The polyalkylene glycol mono(meth)acrylic acid ester monomer preferably has an average repeating number of alkylene oxides constituting the polyalkylene glycol chain of 3 to 14. The "average repeating number of alkylene oxides" is the average number of repeating alkylene oxide units in the "polyalkylene glycol chain" portion included in the molecular structure of (D) polyalkylene glycol mono(meth)acrylic acid ester monomer.

[0030] (D) The polyalkylene glycol mono(meth)acrylic acid ester monomer is preferably at least one selected from polyalkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, and ethoxypolyalkylene glycol (meth)acrylate. More specifically, polyethylene glycol-mono(meth)acrylate, polypropylene glycol-mono(meth)acrylate, polybutylene glycol-mono(meth)acrylate, polyethylene glycol-polypropylene glycol-mono(meth)acrylate, polyethylene glycol-polybutylene glycol-mono(meth)acrylate, polypropylene glycol-polybutylene glycol-mono(meth)acrylate, polyethylene glycol-polypropylene glycol-polybutylene glycol-mono(meth)acrylate; methoxypolyethylene glycol-(meth)acrylate, methoxypolypropylene glycol-(meth)acrylate, methoxypolybutylene glycol-(meth)acrylate, methoxypolyethylene glycol Examples include polybutylene glycol-(meth)acrylate, methoxy-polypropylene glycol-polybutylene glycol-(meth)acrylate, methoxy-polyethylene glycol-polypropylene glycol-polybutylene glycol-(meth)acrylate; ethoxypolyethylene glycol-(meth)acrylate, ethoxypolypropylene glycol-(meth)acrylate, ethoxypolybutylene glycol-(meth)acrylate, ethoxy-polyethylene glycol-polypropylene glycol-(meth)acrylate, ethoxy-polyethylene glycol-polybutylene glycol-(meth)acrylate, ethoxy-polypropylene glycol-polybutylene glycol-(meth)acrylate, and ethoxypolyethylene glycol-polypropylene glycol-polybutylene glycol-(meth)acrylate. When the total amount of the acrylic polymer copolymer is 100 parts by weight, it is preferable that the (D) polyalkylene glycol mono(meth)acrylic acid monomer is contained in a proportion of 0 to 50 parts by weight. In the adhesive layer according to the present invention, the adhesive composition does not need to contain the (D) polyalkylene glycol mono(meth)acrylic acid monomer.

[0031] (E) includes (E-1) nitrogen-containing vinyl monomers, such as vinyl monomers containing amide bonds, vinyl monomers containing amino groups, and vinyl monomers having a nitrogen-containing heterocyclic structure. More specifically, N-vinyl-2-pyrrolidone, N-vinylpyrrolidone, methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, and N-vinyllaurillolactam, which have an N-vinyl substituted heterocyclic structure. Cyclic nitrogen vinyl compounds having a structure; such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperazine, N-(meth)acryloylaziridine, N-(meth)acryloylazetidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylpiperidine, N-(meth)acryloylazepane, and N-(meth)acryloylazokane, which have an N-(meth)acryloyl-substituted heterocyclic structure. Cyclic nitrogen vinyl compounds; cyclic nitrogen vinyl compounds having a heterocyclic structure with a nitrogen atom and an ethylene-based unsaturated bond in the ring, such as N-cyclohexylmaleimide and N-phenylmaleimide; unsubstituted or monoalkyl-substituted (meth)acrylamides such as (meth)acrylamide, N-methyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and Nt-butyl(meth)acrylamide; dialkyl-substituted (meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropylacrylamide, N,N-diisopropyl(meth)acrylamide, N,N-dibutyl(meth)acrylamide, N-ethyl-N-methyl(meth)acrylamide, N-methyl-N-propyl(meth)acrylamide, and N-methyl-N-isopropyl(meth)acrylamide;Dialkylamino(meth)acrylates such as N,N-dimethylaminomethyl(meth)acrylate, N,N-dimethylaminoethyl(meth)acrylate, N,N-dimethylaminopropyl(meth)acrylate, N,N-dimethylaminoisopropyl(meth)acrylate, N,N-dimethylaminobutyl(meth)acrylate, N,N-diethylaminomethyl(meth)acrylate, N,N-diethylaminoethyl(meth)acrylate, N-ethyl-N-methylaminoethyl(meth)acrylate, N-methyl-N-propylaminoethyl(meth)acrylate, N-methyl-N-isopropylaminoethyl(meth)acrylate, N,N-dibutylaminoethyl(meth)acrylate, t-butylaminoethyl(meth)acrylate, etc.; N,N-dimethylaminopropyl(meth)acrylamide, N,N-diethylaminopropyl(meth)acrylamide, N Examples include N,N-dialkyl-substituted aminopropyl(meth)acrylamides such as N-dipropylaminopropyl(meth)acrylamide, N,N-diisopropylaminopropyl(meth)acrylamide, N-ethyl-N-methylaminopropyl(meth)acrylamide, N-methyl-N-propylaminopropyl(meth)acrylamide, and N-methyl-N-isopropylaminopropyl(meth)acrylamide; N-vinyl carboxylic acid amides such as N-vinylformamide, N-vinylacetamide, and N-vinyl-N-methylacetamide; (meth)acrylamides such as N-methoxymethyl(meth)acrylamide, N-ethoxyethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, diacetone acrylamide, and N,N-methylenebis(meth)acrylamide; and unsaturated carboxylic acid nitriles such as (meth)acrylonitrile.

[0032] (E-1) Nitrogen-containing vinyl monomers are preferably those that do not contain hydroxyl groups, and more preferably those that do not contain hydroxyl groups and carboxyl groups. Preferred monomers for this purpose include the monomers exemplified above, for example, acrylic monomers containing N,N-dialkyl-substituted amino groups or N,N-dialkyl-substituted amide groups; N-vinyl-substituted lactams such as N-vinyl-2-pyrrolidone, N-vinylcaprolactam, and N-vinyl-2-piperidone; and N-(meth)acryloyl-substituted cyclic amines such as N-(meth)acryloylmorpholine and N-(meth)acryloylpyrrolidine.

[0033] Of (E), the (E-2) alkoxy group-containing alkyl (meth)acrylate monomers include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-propoxyethyl (meth)acrylate, 2-isopropoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-methoxypropyl (meth)acrylate, 2-ethoxypropyl (meth)acrylate, 2-propoxypropyl (meth)acrylate, 2-isopropoxypropyl (meth)acrylate, and 2- Examples include toxypropyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 3-propoxypropyl (meth)acrylate, 3-isopropoxypropyl (meth)acrylate, 3-butoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, 4-ethoxybutyl (meth)acrylate, 4-propoxybutyl (meth)acrylate, 4-isopropoxybutyl (meth)acrylate, and 4-butoxybutyl (meth)acrylate. These alkoxy-containing alkyl (meth)acrylate monomers have a structure in which the alkyl group atom in the alkyl (meth)acrylate is substituted with an alkoxy group.

[0034] When the total amount of the acrylic polymer copolymer is 100 parts by weight, it is preferable that it contains (E-1) nitrogen-containing vinyl monomer that does not contain hydroxyl groups or (E-2) alkyl (meth)acrylate monomer that contains alkoxy groups in a proportion of 0 to 20 parts by weight. (E-1) nitrogen-containing vinyl monomer that does not contain hydroxyl groups and (E-2) alkyl (meth)acrylate monomer that contains alkoxy groups may be used individually or in combination of two or more types. In the adhesive layer according to the present invention, the adhesive composition does not need to contain (E) nitrogen-containing vinyl monomer that does not contain hydroxyl groups or alkyl (meth)acrylate monomer that contains alkoxy groups.

[0035] (F) The isocyanate compound with two or more functions may be at least one or more selected from polyisocyanate compounds having at least two or more isocyanate (NCO) groups in one molecule. Polyisocyanate compounds can be classified into aliphatic isocyanates, aromatic isocyanates, acyclic isocyanates, and alicyclic isocyanates, and any of these may be used. Specific examples of polyisocyanate compounds include aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and trimethylhexamethylene diisocyanate (TMDI), and aromatic isocyanate compounds such as diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hydrogenated xylylene diisocyanate (H6XDI), dimethyl diphenyl diisocyanate (TOID), and tolylene diisocyanate (TDI). Examples of isocyanate compounds with three or more functions include bifunctional isocyanate compounds (compounds having two NCO groups in one molecule), such as bifunctional isocyanate compounds, isocyanurate compounds, and adduct compounds (polyol-modified compounds) with trivalent or higher polyols (compounds having at least three OH groups in one molecule) such as trimethylolpropane (TMP) and glycerin. (F) As the isocyanate compound with two or more functions, it is also possible to use only (F-1) trifunctional isocyanate compounds or only (F-2) bifunctional isocyanate compounds. Furthermore, it is also possible to use (F-1) trifunctional isocyanate compounds and (F-2) bifunctional isocyanate compounds in combination.

[0036] Furthermore, the (F-1) trifunctional isocyanate compound used in the present invention is selected from the (F-1-1) first aliphatic isocyanate compound group, which consists of the isocyanurate form of a hexamethylene diisocyanate compound, the isocyanurate form of an isophorone diisocyanate compound, the adduct form of a hexamethylene diisocyanate compound, the adduct form of an isophorone diisocyanate compound, the burette form of a hexamethylene diisocyanate compound, and the burette form of an isophorone diisocyanate compound. It is preferable to include at least one of the following: (F-1-2) at least one selected from the second group of aromatic isocyanate compounds, which consists of isocyanurates of tolylene diisocyanate compounds, isocyanurates of xylylene diisocyanate compounds, isocyanurates of hydrogenated xylylene diisocyanate compounds, adducts of tolylene diisocyanate compounds, adducts of xylylene diisocyanate compounds, and adducts of hydrogenated xylylene diisocyanate compounds. It is preferable to use the first group of aliphatic isocyanate compounds (F-1-1) and the second group of aromatic isocyanate compounds (F-1-2) in combination. In the present invention, by using (F-1) at least one compound selected from the first aliphatic isocyanate compound group and (F-1-2) at least one compound selected from the second aromatic isocyanate compound group as (F-1) trifunctional isocyanate compounds, the balance of adhesive strength in the low-speed peeling region and the high-speed peeling region can be further improved. Furthermore, the (F-1) trifunctional isocyanate compound preferably comprises at least one compound selected from the (F-1-1) first aliphatic isocyanate compound group and at least one compound selected from the (F-1-2) second aromatic isocyanate compound group, and is included in a total of 0.5 to 5.0 parts by weight per 100 parts by weight of the copolymer. Furthermore, the mixing ratio of at least one compound selected from the (F-1-1) first aliphatic isocyanate compound group and at least one compound selected from the (F-1-2) second aromatic isocyanate compound group is preferably in the range of (F-1-1):(F-1-2) by weight ratio of 10%:90% to 90%:10%.

[0037] Furthermore, the (F-2)2-functionalized isocyanate compound used in the present invention is preferably an acyclic aliphatic isocyanate compound, which is a compound produced by reacting a diisocyanate compound with a diol compound. For example, when a diisocyanate compound is represented by the general formula "O=C=NXN=C=O" (where X is a divalent group) and a diol compound is represented by the general formula "HO-Y-OH" (where Y is a divalent group), a compound produced by reacting a diisocyanate compound with a diol compound is, for example, a compound represented by the following general formula Z.

[0038] [General formula Z] O=C=NX-(NH-CO-OYO-CO-NH-X) n -N=C=O

[0039] Here, n is a non-negative integer. When n is 0, the general formula Z represents "O=C=NXN=C=O". The bifunctional acyclic aliphatic isocyanate compound may include a compound in general formula Z where n is 0 (a diisocyanate compound that has not reacted with the diol compound), but it is preferable to include a compound in which n is a non-negative integer as an essential component. The bifunctional acyclic aliphatic isocyanate compound may also be a mixture of multiple compounds in which n in general formula Z is different.

[0040] Diisocyanate compounds represented by the general formula "O=C=NXN=C=O" are aliphatic diisocyanates. X is preferably an acyclic, aliphatic divalent group. The aliphatic diisocyanate is preferably one or more compounds selected from the group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate.

[0041] Diol compounds represented by the general formula "HO-Y-OH" are aliphatic diols. Y is preferably an acyclic, aliphatic divalent group. The diol compound is preferably one or more selected from the group of compounds consisting of 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxypivalate, polyethylene glycol, and polypropylene glycol.

[0042] The weight ratio (F-1 / F-2) of the (F-1) trifunctional isocyanate compound to the (F-2) bifunctional isocyanate compound is preferably 1 to 90. The amount of the (F) bifunctional or more isocyanate compound is preferably 0.1 to 10 parts by weight per 100 parts by weight of the acrylic polymer.

[0043] (G) The metal chelate compound crosslinking catalyst can be any substance that functions as a catalyst for the reaction (crosslinking reaction) between the copolymer and the crosslinking agent when a polyisocyanate compound is used as the crosslinking agent. Examples include amine compounds such as tertiary amines, metal chelate compounds, organotin compounds, organolead compounds, organozinc compounds, and other organometallic compounds. In the present invention, a metal chelate compound is used as the crosslinking catalyst.

[0044] A metal chelate compound is a compound in which one or more polydentate ligands L are bonded to a central metal atom M. A metal chelate compound may or may not have one or more monodentate ligands X bonded to the metal atom M. For example, the general formula for a metal chelate compound with one metal atom M is M(L) m (X) n When expressed as , m≧1 and n≧0. If m is 2 or greater, the m Ls may be the same ligand or different ligands. If n is 2 or greater, the n Xs may be the same ligand or different ligands.

[0045] Examples of metal atoms M include Fe, Ni, Mn, Cr, V, Ti, Ru, Zn, Al, Zr, and Sn. Examples of polydentate ligand L include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate, as well as β-diketones such as acetylacetone (also known as 2,4-pentanedione), 2,4-hexanedione, and benzoylacetone. These are ketoenol tautomer compounds, and in the case of polydentate ligand L, the enol may be deprotonated enolates (e.g., acetylacetonate). Examples of monodentate ligand X include halogen atoms such as chlorine and bromine atoms, acyloxy groups such as pentanoyl, hexanoyl, 2-ethylhexanoyl, octanoyl, nonanoyl, decanoyl, dodecanoyl, and octadecanoyl groups, and alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, and butoxy groups.

[0046] Specific examples of metal chelating compounds include tris(2,4-pentanedionato)iron(III), iron trisacetylacetonate, titanium trisacetylacetonate, ruthenium trisacetylacetonate, zinc bisacetylacetonate, aluminum trisacetylacetonate, zirconium tetrakisacetylacetonate, tris(2,4-hexanedionato)iron(III), bis(2,4-hexanedionato)zinc, tris(2,4-hexanedionato)titanium, tris(2,4-hexanedionato)aluminum, and tetrakis(2,4-hexanedionato)zirconium.

[0047] Examples of organotin compounds include dialkyltin oxides, fatty acid salts of dialkyltin, and fatty acid salts of stannous tin. While dibutyltin compounds have been widely used conventionally, concerns about the toxicity of organotin compounds have been raised in recent years, and tributyltin (TBT), contained in dibutyltin compounds, is particularly concerning as an endocrine disruptor. From a safety standpoint, long-chain alkyltin compounds such as dioctyltin compounds are preferred. Specific examples of organotin compounds include dioctyltin oxide and dioctyltin dilaurate. While Sn compounds can be used provisionally, in light of the trend towards requiring safer substances in the future, it is preferable to use metal chelate compounds such as Al, Ti, and Fe, which are safer than Sn. In the adhesive composition relating to the present invention, it is preferable that the metal chelating compound includes at least one selected from the group consisting of aluminum chelating compounds, titanium chelating compounds, iron chelating compounds, and tin chelating compounds (excluding TBT). (G) The crosslinking catalyst of the metal chelate compound is preferably present in an amount of 0.001 to 0.5 parts by weight per 100 parts by weight of the copolymer.

[0048] Examples of (H) ketoenol tautomer compounds include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate, as well as β-diketones such as acetylacetone, 2,4-hexanedione, and benzoylacetone. In adhesive compositions using polyisocyanate compounds as crosslinking agents, these compounds block the isocyanate groups of the crosslinking agent, thereby suppressing excessive viscosity increases and gelation of the adhesive composition after the addition of the crosslinking agent, and extending the pot life of the adhesive composition. (H) The ketoenol tautomer compound is preferably present in an amount of 0.1 to 200 parts by weight per 100 parts by weight of the copolymer.

[0049] (H) The ketoenol tautomer compound has the opposite effect of inhibiting crosslinking compared to the crosslinking catalyst of the (G) metal chelate compound. Therefore, it is preferable to appropriately set the ratio of the (H) ketoenol tautomer compound to the crosslinking catalyst of the (G) metal chelate compound. To extend the pot life of the adhesive composition and improve storage stability, it is preferable that the weight ratio (H) / (G) of the (H) ketoenol tautomer compound / (G) metal chelate compound crosslinking catalyst is high. The value of (H) / (G) is preferably in the range of 1 to 700, more preferably 30 to 300, and most preferably 80 to 300.

[0050] (I) Examples of antistatic agents include antistatic agents contained in the adhesive composition and antistatic agents copolymerized in the copolymer. Preferably, (I) the antistatic agent is contained in an amount of 0.05 to 5.0 parts by weight per 100 parts by weight of the copolymer. (I) The antistatic agent is preferably (I-1) an ionic compound having a melting point of 25 to 50°C, and / or (I-2) an ionic compound containing an acryloyl group. In the present invention, (I) as an antistatic agent, (I-1) an ionic compound having a melting point of 25 to 50 °C is added to the copolymer, and / or (I-2) an acryloyl group-containing ionic compound is copolymerized in the copolymer. Since these (I) antistatic agents have a low melting point and have a long-chain alkyl group, it is presumed that they have a high affinity for the acrylic copolymer.

[0051] (I-1) As the ionic compound having a melting point of 25 to 50 °C, it is an ionic compound having a cation and an anion, and the cation is a nitrogen-containing onium cation such as a pyridinium cation, an imidazolium cation, a pyrimidinium cation, a pyrazolium cation, a pyrrolidinium cation, an ammonium cation, etc., or a phosphonium cation, a sulfonium cation, etc., and the anion is a phosphate hexafluoride (PF6 - ), a thiocyanate (SCN - ), an alkylbenzene sulfonate (RC6H4SO3 - ), a perchlorate (ClO4 - ), a tetrafluoroborate (BF4 - ), a bis(fluorosulfonyl)imide salt (FSI), a bis(trifluoromethanesulfonyl)imide salt (TFSI), a trifluoromethanesulfonate (TF), or other inorganic or organic anionic compounds. It is preferably solid at room temperature (for example, 25 °C), and by selecting the chain length of the alkyl group, the position and number of substituents, etc., those having a melting point of 25 to 50 °C can be obtained. The cation is preferably a quaternary nitrogen-containing onium cation, such as a quaternary pyridinium cation such as 1-alkylpyridinium (the carbon atoms at the 2nd to 6th positions may have substituents or may be unsubstituted), or a quaternary imidazolium cation such as 1,3-dialkylimidazolium (the carbon atoms at the 2nd, 4th, and 5th positions may have substituents or may be unsubstituted), or a quaternary ammonium cation such as tetraalkylammonium, etc. (I-1) The ionic compound having a melting point of 25 to 50 °C is preferably contained in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the copolymer.

[0052] (I-2) Acryloyl group-containing ionic compounds include ionic compounds having a cation and anion, wherein the cation is (meth)acryloyloxyalkyltrialkylammonium [R3N + -C n H 2n -OCOCQ=CH2, where Q=H or CH3, R=alkyl] is a (meth)acryloyl group-containing cation, and the anion is hexafluoride phosphate (PF6 - ), thiocyanate (SCN - ), organic sulfonates (RSO3 - ), perchlorate (ClO4 - ), tetrafluoroborate (BF4 - ), F-containing imide salt (R F 2N - Examples include compounds that are inorganic or organic anions, such as ) and F-containing imide salts (R F 2N - ) of R F Examples include perfluoroalkanesulfonyl groups such as trifluoromethanesulfonyl groups and pentafluoroethanesulfonyl groups, as well as fluorosulfonyl groups. Examples of fluorine-containing imide salts include bis(fluorosulfonyl)imide salt [(FSO2)2N - ], bis(trifluoromethanesulfonyl)imide salt [(CF3SO2)2N - ], bis(pentafluoroethanesulfonyl)imide salt [(C2F5SO2)2N - Examples of bissulfonylimide salts include the following: (I-2) The acryloyl group-containing ionic compound is preferably copolymerized in the copolymer at a concentration of 0.1 to 5.0% by weight.

[0053] (I) Specific examples of antistatic agents are not particularly limited, but (I-1) specific examples of ionic compounds with a melting point of 25-50°C include 1-octylpyridinium hexafluoride phosphate, 1-nonylpyridinium hexafluoride phosphate, 2-methyl-1-dodecylpyridinium hexafluoride phosphate, 1-octylpyridinium dodecylbenzenesulfonate, 1-dodecylpyridinium thiocyanate, 1-dodecylpyridinium dodecylbenzenesulfonate, 4-methyl-1-octylpyridinium hexafluoride phosphate, and quaternary ammonium salts of trifluoromethanesulfonic acid. Also, (I-2) specific examples of acryloyl group-containing ionic compounds include dimethylaminomethyl (meth)acrylate methyl hexafluoride phosphate [(CH3)3N + CH2OCOCQ=CH2·PF6 - However, Q=H or CH3], Dimethylaminoethyl (meth)acrylate bis(trifluoromethanesulfonyl)imide methyl salt [(CH3)3N + (CH2)2OCOCQ=CH2·(CF3SO2)2N - However, Q=H or CH3], Dimethylaminomethyl methacrylate bis(fluorosulfonyl)imidomethyl salt [(CH3)3N + CH2OCOCQ=CH2·(FSO2)2N - However, examples include Q = H or CH3.

[0054] The adhesive composition of the present invention contains a (J) polyether-modified siloxane compound. The (J) polyether-modified siloxane compound is a siloxane compound having a polyether group, and has a normal siloxane unit [-SiR 1 In addition to 2-O-, there are siloxane units having a polyether group [-SiR 1 (R 2 O(R 3 O) n R 4 It has )-O-]. Here, R 1 R is one or more alkyl or aryl groups, 2 and R 3 R is one or more alkylene groups,4 This represents one or more alkyl groups or acyl groups (terminal groups). Examples of polyether groups include polyoxyethylene groups [(C2H4O)] n ] and polyoxypropylene group [(C3H6O) n Examples of polyoxyalkylene groups include the following: (J) The polyether-modified siloxane compound is preferably a polyether-modified siloxane compound having an HLB value of 7 to 15. Furthermore, it is preferable that the (J) polyether-modified siloxane compound is present in an amount of 0.01 to 1.0 parts by weight per 100 parts by weight of the copolymer. More preferably, it is 0.1 to 0.5 parts by weight. HLB refers to the hydrophilic-lipophilic balance (hydrophilic-lipophilic ratio) as defined in standards such as JIS K3211 (Terminology for Surfactants). (J) Polyether-modified siloxane compounds can be obtained, for example, by grafting an organic compound having unsaturated bonds and polyoxyalkylene groups onto a polyorganosiloxane main chain having silicon hydride groups via a hydrosilylation reaction. Specifically, examples include dimethylsiloxane-methyl(polyoxyethylene)siloxane copolymer, dimethylsiloxane-methyl(polyoxyethylene)siloxane-methyl(polyoxypropylene)siloxane copolymer, and dimethylsiloxane-methyl(polyoxypropylene)siloxane polymer. (J) By incorporating a polyether-modified siloxane compound into the adhesive composition, the adhesive strength and rework performance of the adhesive can be improved. If the adhesive composition does not contain a polyether-modified siloxane compound, the cost will be lower.

[0055] The adhesive composition of the present invention contains (K) an antioxidant. Examples of (K) antioxidants include hindered phenol antioxidants, polyphenol compounds, and tocopherol compounds. Among these, tocopherol compounds are preferred. Tocopherol compounds are generally vitamin E and are naturally derived chemical substances. For this reason, they have few adverse effects on the human body, are highly safe to handle, and are environmentally friendly. Furthermore, because they are oil-soluble and liquid at room temperature, they have excellent compatibility with adhesive compositions and excellent resistance to precipitation. By incorporating tocopherol compounds as (K) antioxidants, the storage stability of the adhesive is improved, and the pot life of the adhesive composition containing the curing agent is improved. The tocopherol-based compounds used in this invention are preferred because they are incorporated into adhesive compositions (and do not undergo metabolism as in the human body), and therefore the ferrule hydroxyl groups of tocopherol have not been converted to esters or the like, and the compounds have ferrule hydroxyl groups. Examples include tocopherol and tocotrienol. Tocopherol and tocotrienol are known to be classified into natural compounds (d-form), unnatural compounds (l-form), and racemic mixtures (dl-form) which are equimolar mixtures of these. Natural compounds (d-form) and racemic mixtures (dl-form) are preferred because some are used as food additives, etc. Specific examples of tocopherol compounds include at least one selected from the group of compounds consisting of d-α-tocopherol, dl-α-tocopherol, d-β-tocopherol, dl-β-tocopherol, d-γ-tocopherol, dl-γ-tocopherol, d-δ-tocopherol, dl-δ-tocopherol, d-α-tocotrienol, dl-α-tocotrienol, d-β-tocotrienol, dl-β-tocotrienol, d-γ-tocotrienol, dl-γ-tocotrienol, dl-δ-tocotrienol, and dl-δ-tocotrienol. Two or more tocopherol compounds may be used in combination. As food additives, "mixed tocopherols" are a mixture mainly composed of d-α-tocopherol, d-β-tocopherol, d-γ-tocopherol, and d-δ-tocopherol, while "tocotrienols" are a mixture mainly composed of d-α-tocotrienol, d-β-tocotrienol, d-γ-tocotrienol, and d-δ-tocotrienol. The adhesive composition of the present invention preferably contains 0.01 to 5 parts by weight of a tocopherol-based compound per 100 parts by weight of the copolymer.

[0056] Furthermore, other known additives containing alkylene oxides, such as copolymerizable (meth)acrylic monomers, (meth)acrylamide monomers, dialkyl-substituted acrylamide monomers, surfactants, curing catalysts, plasticizers, fillers, curing retarders, processing aids, anti-aging agents, and antioxidants, can be appropriately blended as other components. These can be used individually or in combination of two or more.

[0057] The copolymer of the main component used in the adhesive composition of the present invention can be synthesized by copolymerizing (A) at least one (meth)acrylic acid ester monomer having C4 to C18 C in its alkyl group with at least one selected from the copolymerizable monomer group consisting of (B) copolymerizable monomers containing a hydroxyl group, (C) copolymerizable monomers containing a carboxyl group, (D) polyalkylene glycol mono(meth)acrylic acid ester monomer, and (E) nitrogen-containing vinyl monomer or alkyl(meth)acrylate monomer containing an alkoxy group that does not contain a hydroxyl group. The polymerization method of the copolymer is not particularly limited, and any suitable polymerization method such as solution polymerization or emulsion polymerization can be used. (I) When an acryloyl group-containing ionic compound is used as an antistatic agent, the copolymer of the main component used in the adhesive composition of the present invention can be synthesized by copolymerizing (A) at least one (meth)acrylic acid ester monomer having C4 to C18 C atoms in the alkyl group, at least one selected from the copolymerizable monomer group consisting of (B) copolymerizable monomers containing a hydroxyl group, (C) copolymerizable monomers containing a carboxyl group, (D) polyalkylene glycol mono(meth)acrylic acid ester monomer, and (E) nitrogen-containing vinyl monomer or alkyl(meth)acrylate monomer containing an alkoxy group that does not contain a hydroxyl group, with (I-2) an acryloyl group-containing ionic compound. The adhesive composition of the present invention can be prepared by blending the above copolymer with (F) a bifunctional or more isocyanate compound, (G) a crosslinking catalyst of a metal chelate compound, (H) a ketoenol tautomer compound, (I) an antistatic agent, (J) a polyether-modified siloxane compound, (K) an antioxidant, and any other additive as appropriate. Furthermore, when (I-2) an acryloyl group-containing ionic compound is polymerized into the copolymer, (I) an antistatic agent may or may not be added to the copolymer.

[0058] The copolymer is preferably an acrylic polymer, and more preferably contains 50 to 100% by weight of an acrylic monomer such as (meth)acrylic acid ester monomer, (meth)acrylic acid, or (meth)acrylamide. Furthermore, the acid value of the acrylic polymer is preferably between 0.01 and 8.0. This improves stain resistance and enhances the ability to prevent adhesive residue. Here, "acid value" is one of the indicators that represents the acid content, and is expressed as the number of milligrams of potassium hydroxide required to neutralize 1 gram of polymer containing carboxyl groups.

[0059] Preferably, the adhesive layer formed by crosslinking the aforementioned adhesive composition has an adhesive strength of 0.05 to 0.1 N / 25 mm at a low peeling speed of 0.3 m / min, and an adhesive strength of 1.0 N / 25 mm or less at a high peeling speed of 30 m / min. This results in a performance where the adhesive strength does not change much with the peeling speed, and allows for quick peeling even at high speeds. Furthermore, when peeling off the surface protective film for reapplication, it does not require excessive force and is easy to peel off from the adherend.

[0060] The adhesive layer formed by crosslinking the aforementioned adhesive composition has a surface resistivity of 9.0 × 10 +11 The resistivity is preferably Ω / □ or less, and the peel band voltage is preferably ±0 to 0.5kV. In this invention, "±0 to 0.5kV" means 0 to -0.5kV and 0 to +0.5kV, i.e., -0.5 to +0.5kV. If the surface resistivity is high, the ability to dissipate static electricity generated by charging during peeling is poor. By making the surface resistivity sufficiently low, the peel band voltage generated by static electricity when the adhesive layer is peeled off by the adherend can be reduced, thereby suppressing its impact on the electrical control circuit of the adherend.

[0061] The gel fraction of the adhesive layer (adhesive after crosslinking) obtained by crosslinking the adhesive composition of the present invention is preferably 95 to 100%. This high gel fraction prevents excessive adhesion at low peeling speeds, reduces the elution of unpolymerized monomers or oligomers from the copolymer, improves reworkability and durability at high temperatures and humidity, and suppresses contamination of the adherend.

[0062] The adhesive film of the present invention is formed by creating an adhesive layer on one or both sides of a resin film, which is formed by crosslinking the adhesive composition of the present invention. The surface protection film of the present invention is a surface protection film formed by creating an adhesive layer on one side of a resin film, which is formed by crosslinking the adhesive composition of the present invention. Because the adhesive composition of the present invention contains a well-balanced blend of the above components (A) to (K), it has excellent antistatic properties, excellent balance of adhesive strength at both low and high peeling speeds, and also excellent durability and reworkability (no contamination transfer to the adherend after tracing over the surface protection film with a ballpoint pen via the adhesive layer). For this reason, it can be suitably used as a surface protection film for polarizing plates.

[0063] For the base film of the adhesive layer and the release film (separator) that protects the adhesive surface, resin films such as polyester film can be used. The base film can be treated with antifouling treatments such as silicone-based or fluorine-based release agents or coatings, silica microparticles, etc., on the side opposite to the side where the adhesive layer of the resin film is formed, or with antistatic treatments such as application or mixing of antistatic agents. The release film is treated with a release agent, such as a silicone-based or fluorine-based release agent, on the side that comes into contact with the adhesive surface of the adhesive layer. [Examples]

[0064] The present invention will be specifically described below with reference to examples.

[0065] <Manufacturing of acrylic copolymers> [Example 1] Nitrogen gas was introduced into a reactor equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube to replace the air in the reactor with nitrogen gas. Then, 100 parts by weight of 2-ethylhexyl acrylate, 3.0 parts by weight of 8-hydroxyoctyl acrylate, 0.4 parts by weight of acrylic acid, and 10 parts by weight of polypropylene glycol monoacrylate (average repeat number of alkylene oxides constituting the polyalkylene glycol chain n=12) were added to the reactor along with 60 parts by weight of solvent (ethyl acetate). Subsequently, 0.1 parts by weight of azobisisobutyronitrile was added dropwise over 2 hours as a polymerization initiator, and the reaction was carried out at 65°C for 6 hours to obtain acrylic copolymer solution 1, which was used in Example 1, with a weight-average molecular weight of 500,000. A portion of the acrylic copolymer was taken and used as a sample for measuring the acid value, as described later. [Examples 2-6 and Comparative Examples 1-7] Except for the monomer compositions being as described in (A) to (E) and (I-2) of Table 1, the acrylic copolymer solutions used in Examples 2 to 6 and Comparative Examples 1 to 7 were obtained in the same manner as acrylic copolymer solution 1 used in Example 1 above.

[0066] [Table 1]

[0067] <Manufacturing of adhesive compositions and surface protective films> [Example 1] To the acrylic copolymer solution 1 of Example 1, prepared as described above, 1.5 parts by weight of 1-octylpyridinium hexafluoride phosphate, 0.05 parts by weight of polyether-modified siloxane compound (HLB=7), 8.5 parts by weight of acetylacetone, and 0.1 parts by weight of α-tocopherol were added and stirred. Then, 2.0 parts by weight of Coronate HX (isocyanurate of hexamethylene diisocyanate compound) and 0.1 parts by weight of titanium trisacetylacetonate were added and stirred to obtain the adhesive composition of Example 1. This adhesive composition was applied to a release film made of silicone resin-coated polyethylene terephthalate (PET) film, and the solvent was removed by drying at 90°C to obtain an adhesive sheet with an adhesive layer thickness of 25 μm. Subsequently, an adhesive sheet was transferred to the side of a polyethylene terephthalate (PET) film that had been treated with antistatic and antifouling properties on one side, opposite to the side that had been treated with antistatic and antifouling properties, thereby obtaining the surface protection film of Example 1 having a laminated structure of "antistatic and antifouling treated PET film / adhesive layer / release film (silicone resin coated PET film)". [Examples 2-6 and Comparative Examples 1-7] Except for using additive compositions as shown in (F) to (K) in Table 2, surface protective films for Examples 2 to 6 and Comparative Examples 1 to 7 were obtained in the same manner as the surface protective film for Example 1 described above.

[0068] [Table 2]

[0069] Tables 1 and 2 are two separate tables showing the mixing ratios of each component. In both tables, the values ​​in parts by weight are shown in parentheses, calculated with the total of group (A) set at 100 parts by weight. The ratio of (H) / (G) is shown in Table 3. The compound names of the abbreviated symbols used for each component in Tables 1 and 2 are shown in Tables 4 and 5. Note that Coronate® HX, HL, and L are trade names of Nippon Polyurethane Industry Co., Ltd., Takenate® D-140N, D-127N, D-110N, and D-120N are trade names of Mitsui Chemicals, Inc., and Desmodule® N3400 is a trade name of Sumika Bayer Urethane Co., Ltd. In Table 1, among the (I) antistatic agents, (I-2) acryloyl group-containing ionic compounds copolymerized in the copolymer are listed in a separate column from the (I) antistatic agents added after polymerization.

[0070] [Table 3]

[0071] [Table 4]

[0072] [Table 5]

[0073] <Synthesis of bifunctional isocyanate compounds> The bifunctional isocyanate compounds in Synthesis Examples 1-3 were synthesized by the following method. As shown in Tables 6 and 7, diisocyanate and diol compounds were mixed in a molar ratio of NCO / OH = 16 and reacted at 120°C for 3 hours. Then, unreacted diisocyanate was removed under reduced pressure using a thin-film evaporator to obtain the desired bifunctional isocyanate compounds.

[0074] [Table 6]

[0075] [Table 7]

[0076] <Test Methods and Evaluation> The surface protective films from Examples 1-6 and Comparative Examples 1-7 were aged for 7 days at 23°C and 50% RH. After aging, the release film (silicone resin-coated PET film) was peeled off to expose the adhesive layer, which was then used as the sample for surface resistivity measurement. Furthermore, this surface protection film with the adhesive layer exposed was bonded to the surface of a polarizing plate attached to a liquid crystal cell via the adhesive layer, left for one day, then autoclaved at 50°C, 5 atmospheres for 20 minutes, and left at room temperature for another 12 hours. This was used as a sample for measuring adhesive strength, peel voltage, reworkability, and durability.

[0077] <Adhesive strength> The sample obtained above (a 25 mm wide surface protective film laminated onto the surface of a polarizing plate) was peeled off in the 180° direction using a tensile testing machine at a low peeling speed (0.3 m / min) and a high peeling speed (30 m / min), and the measured peel strength was defined as the adhesive strength.

[0078] <Surface resistivity> After aging, before bonding to the polarizing plate, the release film (silicone resin-coated PET film) was peeled off to expose the adhesive layer, and the surface resistivity of the adhesive layer was measured using a resistivity meter, Hi-Resta UP-HT450 (manufactured by Mitsubishi Chemical Analytec).

[0079] <Strip voltage> The voltage (band voltage) generated when the polarizing plate becomes charged during the peeling of the sample obtained above at a tensile speed of 30 m / min at 180° was measured using high-precision electrostatic sensors SK-035 and SK-200 (manufactured by Keyence Corporation), and the maximum value of the measured value was defined as the peeled band voltage.

[0080] <Reworkability> After tracing the surface protective film of the measurement sample obtained above with a ballpoint pen (load 500g, 3 back-and-forth strokes), the surface protective film was peeled off the polarizing plate and the surface of the polarizing plate was observed to confirm that there was no contamination transfer to the polarizing plate. The evaluation criteria were as follows: "○" if there was no contamination transfer to the polarizing plate, "△" if contamination transfer was confirmed at least partially along the traced path of the ballpoint pen, and "×" if contamination transfer was confirmed along the traced path of the ballpoint pen and the adhesive was also confirmed to have detached from the adhesive surface.

[0081] <Pot Life> The viscosity η0 (initial viscosity) of the adhesive composition was measured immediately after adding additives (F) to (K), and the viscosity η1 (viscosity after 8 hours) of the adhesive composition was measured after leaving it in a sealed state at 23°C for 8 hours. As an indicator of pot life, the value of η1 when η0 is set to 1.0, i.e., the ratio of η1 / η0, was calculated. The evaluation target criteria were as follows: if the viscosity after 8 hours was less than 1.25 times the initial viscosity, it was evaluated as "○"; if it was 1.25 times or more but less than 1.50 times, it was evaluated as "△"; and if it was 1.50 times or more, or if it gelled after 8 hours, it was evaluated as "×".

[0082] <Durability> The sample obtained above was left in an atmosphere of 60°C and 90% RH for 250 hours, then removed to room temperature and left for another 12 hours. The adhesive strength was then measured and confirmed to be no significant increase compared to the initial adhesive strength. The evaluation criteria were as follows: if the adhesive strength after the test was 1.5 times or less of the initial adhesive strength, it was evaluated as "○"; if it exceeded 1.5 times, it was evaluated as "×".

[0083] Table 8 shows the evaluation results. Note that the surface resistivity is "m × 10 +n This was expressed using the formula "mE+n" (where m is an arbitrary real number and n is a positive integer).

[0084] [Table 8]

[0085] The surface protective films in Examples 1-6 had an adhesive strength of 0.05-0.1 N / 25 mm at a low peeling speed of 0.3 m / min, an adhesive strength of 1.0 N / 25 mm or less at a high peeling speed of 30 m / min, and a surface resistivity of 9.0 × 10⁻⁶. +11 The resistance was less than Ω / □, the delamination voltage was ±0 to 0.5kV, there was no contamination transfer to the substrate after tracing over the surface protective film with a ballpoint pen via the adhesive layer, it had a long pot life, and it exhibited excellent durability when left for 250 hours in an atmosphere of 60°C and 90%RH. In other words, it possesses antistatic properties, offers an excellent balance of adhesive strength at both low and high peeling speeds, and also boasts a long pot life, superior durability, and reworkability. Furthermore, the surface protective films of Examples 1 to 6 are highly safe because the adhesive composition does not contain organotin compounds.

[0086] The surface protective film of Comparative Example 1, perhaps because it did not contain an isocyanate compound with two or more (F) functions as a crosslinking agent, had excessively high adhesive strength at low peeling speeds of 0.3 m / min and high peeling speeds of 30 m / min, resulting in a high peeling voltage and poor reworkability and durability. The surface protective film in Comparative Example 2 had a low ratio of (H) ketoenol tautomer compound to (G) metal chelate compound crosslinking catalyst, an excessively high HLB value of (J) polyether-modified siloxane compound, and (K) no antioxidant, resulting in a high peel voltage, short pot life, and poor durability. The surface protective film in Comparative Example 3 used an organotin compound crosslinking catalyst instead of a metal chelate compound crosslinking catalyst (G), and did not contain an antioxidant (K). As a result, the pot life was too short, and crosslinking progressed before application, making coating impossible. The surface protective film in Comparative Example 4 did not contain either (G) a crosslinking catalyst of a metal chelate compound or (H) a ketoenol tautomer compound, nor did it contain (J) a polyether-modified siloxane compound or (K) an antioxidant. As a result, it had excessively high adhesive strength at a high peeling speed of 30 m / min, a short pot life, and poor durability. Thus, the surface protection films in Comparative Examples 1 to 4 failed to simultaneously meet all the required performance characteristics, including antistatic properties, excellent balance of adhesive strength at both low and high peeling speeds, long pot life, and superior durability and reworkability. Furthermore, in the surface protective films of Comparative Examples 5-7, the crosslinking catalyst is an organotin compound rather than a metal chelate compound, which may raise safety concerns in the future.

Claims

1. An adhesive composition containing an acrylic polymer and a crosslinking agent, The acrylic polymer is an acrylic polymer copolymer having an acid value of 0.01 to 8.0, comprising: (A) at least one (meth)acrylic acid ester monomer having C4 to C18 C in its alkyl group; and at least one selected from a copolymerizable monomer group consisting of (B) copolymerizable monomers containing a hydroxyl group; (C) copolymerizable monomers containing a carboxyl group; (D) polyalkylene glycol mono(meth)acrylic acid ester monomer; and (E) nitrogen-containing vinyl monomer or alkyl(meth)acrylate monomer containing an alkoxy group that does not contain a hydroxyl group. The proportions of the above acrylic polymers are as follows: (A) 50 to 95 parts by weight of at least one (meth)acrylic acid ester monomer having C4 to C18 C atoms in the alkyl group, (B) 0.1 to 10 parts by weight of copolymerizable monomer containing a hydroxyl group, and (C) 0.1 to 1.0 part by weight of copolymerizable monomer containing a carboxyl group, per 100 parts by weight of the total acrylic polymer. Furthermore, per 100 parts by weight of the copolymer, the crosslinking agent contains (F) 0.1 to 10 parts by weight of a bifunctional or more isocyanate compound, (J) 0.01 to 1.0 parts by weight of a polyether-modified siloxane compound, and (K) 0.01 to 5 parts by weight of an antioxidant. (I) An adhesive composition characterized by containing 0.1 to 5.0 parts by weight of an ionic compound having a melting point of 25 to 50°C per 100 parts by weight of the copolymer as an antistatic agent, and / or by copolymerizing 0.1 to 5.0% by weight of an acryloyl group-containing ionic compound in the copolymer.

2. The copolymerizable monomer containing a hydroxyl group (B) is at least one selected from the group of compounds consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxyethyl (meth)acrylamide. The copolymerizable monomer containing the carboxyl group (C) is at least one selected from the group of compounds consisting of (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl maleic acid, carboxypolycaprolactone mono(meth)acrylate, and 2-(meth)acryloyloxyethyl tetrahydrophthalic acid. The adhesive composition according to claim 1, characterized in that 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, and is selected from polyalkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, and ethoxypolyalkylene glycol (meth)acrylate, with at least one of these being the same.

3. The adhesive composition according to claim 1 or 2, characterized in that the (K) antioxidant is a tocopherol-based antioxidant.

4. The copolymer contains, per 100 parts by weight, (G) 0.001 to 0.5 parts by weight of a metal chelate crosslinking catalyst and (H) 0.1 to 200 parts by weight of a ketoenol tautomer compound. The adhesive composition according to any one of claims 1 to 3, characterized in that the weight ratio (H) / (G) of the crosslinking catalyst of the (H) ketoenol tautomer compound and the (G) metal chelate compound is 1 to 700.

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