TW201936853A - Adhesive composition and surface protection film - Google Patents

Abstract

The present invention provides an adhesive composition and a surface-protective film that have a long pot life and a fast crosslinking rate without using an organic tin compound. The present invention, with respect to 100 parts by weight of a copolymer of (A) at least one (meth)acrylic acid ester monomer having a C4to C18alkyl group and, as copolymerizable monomers, (B) hydroxyl group-containing copolymerizable monomers, contains 0.1 to 10 parts by weight of (C) a bifunctional or higher isocyanate compound, 0.001 to 0.5 parts by weight of (D) a cross-linking promoting agent of a metal chelate compound, and 0.1 to 300 parts by weight of (E) a keto-enol tautomer compound, wherein the parts by weight ratio of (E)/(D) is 70 to 1,000.

Description

Adhesive composition and surface protective film

The invention relates to an adhesive composition and a surface protective film. In more detail, since the use of organotin compounds that have an adverse effect on the environment has been restricted in recent years, the present invention relates to a method for using a cross-linking catalyst of a metal chelate compound other than an organotin compound without using organotin. In the case of the compound, the adhesive composition and the surface protective film also have a long shelf life and a high cross-linking speed.

From the viewpoint of excellent transparency, the adhesive composition for optical applications is preferably copolymerized with an acrylic monomer having an alkyl (meth) acrylate as a main component and having a hydroxyl group, a carboxyl group, etc. as a functional group. Acrylic adhesive composed of the resulting copolymer. In addition, it is necessary to appropriately adjust various physical properties such as the adhesive force of the adhesive layer. In particular, in order to be suitable for manufacturing processes for factory production, the adhesive layer for a surface protective film is required to be suitable for bonding by an automatic bonding device, and the adhesive force at a low peeling speed and a high peeling speed is required. Excellent balance. In addition, there is a need for an adhesive composition which is excellent in various physical properties such as a long shelf life in addition to the balance of the adhesive force.

For this method of adjusting various physical properties of the adhesive layer, an isocyanate-based crosslinking agent or epoxy-based compound that reacts with functional groups such as a hydroxyl group and a carboxyl group contained in an acrylic adhesive composed of a copolymer can be used. A cross-linking agent and the like perform a cross-linking reaction to adjust adhesion and cohesion.

Conventionally, as a crosslinking agent of an acrylic adhesive, an isocyanate-based crosslinking agent has generally been used. In addition, in a cross-linking reaction using an isocyanate-based cross-linking agent, a metal chelate is often used as a catalyst for promoting the cross-linking reaction.
In general, an organic tin compound, such as dibutyltin dilaurate, is used as a catalyst for the crosslinking reaction from the viewpoint of an excellent reaction speed of the crosslinking reaction. However, the dibutyltin compound is currently being avoided because of its harmful toxicity.
Therefore, there is a need for a cross-linking catalyst which can be used in combination with an isocyanate-based cross-linking agent as a substitute for a dibutyltin compound, and which is inexpensive and has a high reaction speed in the cross-linking reaction.

In view of this situation, Patent Document 1 discloses the following: As a cross-linking catalyst that can be used in combination with an isocyanate-based cross-linking agent, among metal chelates, iron chelates are preferred; Cobalt iron is particularly excellent in its catalytic activity.

However, the acryl-based adhesive composition containing a cross-linking catalyst slowly undergoes a cross-linking reaction even when it is left at room temperature. Therefore, in the industrial production of the binder, a crosslinking catalyst and a reaction inhibitor are usually used in combination in order to stop the crosslinking reaction from the time when the raw material of the binder composition is prepared to the start of the crosslinking reaction.
Regarding the combined use of the cross-linking catalyst and the reaction inhibitor, Patent Document 2 discloses a method for producing polyurethane, in which a reaction polyurethane mixture is used, the reaction polyurethane mixture containing at least one metal acetamidine and acetamidine acetone. A catalyst system prepared by mixing and having a weight ratio of the aforementioned metal acetoacetone to the aforementioned acetoacetone of 2: 1.
[Prior technical literature]
[Patent Literature]

[Patent Document 1] JP 2011-001440
[Patent Document 2] JP 2008-285681

[Problems to be Solved by the Invention]

Regarding the binder composition described in Patent Document 1, the amount of the metal compound (crosslinking catalyst) added to the copolymer containing a (meth) acrylate as a constituent monomer unit and containing a hydroxyl group and a carboxyl group is proposed. However, the amount of the cross-linking inhibitor added is not described. In addition, in Patent Document 1, as a method of suppressing the viscosity increase rate after the crosslinking agent is blended in the adhesive composition, a method using a reaction inhibitor, a method of adding a solvent that suppresses viscosity increase, and the like are used. A method of a cross-linking agent that blocks a functional group such as a block isocyanate and the like is not specifically described.

In addition, Patent Document 2 discloses a method for producing polyurethane, in which the catalyst system used contains a metal acetone catalyst such as iron, copper, or the like, which has very high activity at low temperatures, which does not cause early curing and has excellent properties. The stability and good catalytic activity of metal acetoacetone and acetoacetone.
However, in the method described in Patent Document 2, the weight ratio of metal acetoacetone to acetoacetone is set to 2: 1. However, even when this blending ratio is used in the manufacturing process of an acrylic adhesive, it is not possible. The crosslinking reaction is temporarily stopped.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide an adhesive composition and a surface protective film that have a long storage period and a high cross-linking speed without using an organotin compound.
[Technical means to solve the invention]

In order to solve the above problems, the present invention provides a binder composition in which at least one of (C) to C18 (meth) acrylate monomers having a carbon number of C4 to C18 with respect to the (A) alkyl group is a copolymerizable monomer. (B) 100% by weight of a copolymer of a hydroxyl group-containing copolymerizable monomer, (C) 0.1 to 10 parts by weight of a difunctional or higher isocyanate compound, and (D) a metal chelate crosslinking catalyst 0.001 to 0.5 by weight And (E) the keto-enol tautomer compound is 0.1 to 300 parts by weight, and the ratio of the (E) / (D) part by weight is 70 to 1,000.

In addition, it is preferable that the viscosity of the adhesive composition after storage at 23 ° C. for 8 hours after the adhesive composition is prepared is lower than 1.25 times the viscosity immediately after the formulation.

In addition, it is preferred that the (B) hydroxyl-containing copolymerizable monomer is selected from the group consisting of 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4- Hydroxybutyl, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamine At least one or more of the compound group consisting of amines.

Among the above-mentioned (C) difunctional or higher isocyanate compounds, as the difunctional isocyanate compound, an acyclic aliphatic isocyanate compound and a diisocyanate compound and a diol compound are preferably produced. The diisocyanate compound is an aliphatic diisocyanate, and is preferably selected from the group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate. And lysine diisocyanate. The diol compound is preferably selected from 2-methyl 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, and 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 monohydroxy It is composed of one of a compound group consisting of pivalate, polyethylene glycol, and polypropylene glycol.
In addition, as the trifunctional isocyanate compound (C) or more, the trifunctional isocyanate compound is preferably an isocyanurate selected from the group consisting of a hexamethylene diisocyanate compound and an isophorone diisocyanate compound. Cyanurate, adduct of hexamethylene diisocyanate compound, adduct of isophorone diisocyanate compound, biuret of hexamethylene diisocyanate compound, condensation of isophorone diisocyanate compound Addition of diurea, isocyanurate of toluene diisocyanate compound, isocyanurate of xylylene diisocyanate compound, isocyanurate of hydrogenated xylylene diisocyanate compound, addition of toluene diisocyanate compound Compounds, adducts of xylylene diisocyanate compounds, and at least one compound group consisting of adducts of hydrogenated xylylene diisocyanate compounds.

Moreover, in the said binder composition, as said crosslinking catalyst, it is preferable not to contain an organic tin compound.

The copolymer is preferably an acrylic polymer including at least one of a carboxyl group-containing monomer and a hydroxyl group-containing nitrogen-containing vinyl monomer as another copolymerizable monomer group.

In addition, the gel fraction of the adhesive composition after crosslinking is preferably 90 to 100%.

In addition, it is preferable that the adhesive force of the adhesive layer formed by cross-linking the adhesive composition at a low peeling speed of 0.3 m / min is 0.05 to 0.2 N / 25 mm and the adhesive force at a high peeling speed of 30 m / min. It is 2.0N / 25mm or less.

In addition, the present invention provides an adhesive film formed by forming an adhesive layer on one or both sides of a resin film, and the adhesive layer is formed by cross-linking the aforementioned adhesive composition.

In addition, the present invention provides a surface protection film, which is a surface protection film formed by forming an adhesive layer on one side of a resin film, and the adhesive layer is obtained by cross-linking the adhesive composition.

The surface protection film of the present invention can be used as a surface protection film for a polarizing plate.

In addition, the surface protection film of the present invention can be used as a surface protection film for precision electrical / electronic components. The precision electrical / electronic components are selected from flexible printed circuit boards, rigid printed circuit boards, and transparent conductive materials. Any of the precise electrical / electronic component groups composed of a flexible film.
[Inventive effect]

According to the present invention, it is possible to provide an adhesive composition and a surface protective film that have a long storage period and a fast cross-linking speed without using an organotin compound.
In addition, according to the surface protection film of the present invention, the adhesive composition does not contain a toxic organic tin compound, and therefore has high safety.

[Practice of Invention]

Hereinafter, the present invention will be described based on preferred embodiments.
The adhesive composition of the present invention is characterized in that at least one of (C) to C18 (meth) acrylic acid ester monomers with respect to the (A) alkyl group and (B ) 100 parts by weight of a copolymer of a hydroxyl-containing copolymerizable monomer, (C) 0.1 to 10 parts by weight of a difunctional or higher isocyanate compound, (D) 0.001 to 0.5 parts by weight of a metal chelate crosslinking catalyst, and (E ) The keto-enol tautomer compound is 0.1 to 300 parts by weight, and the weight ratio of (E) / (D) is 70 to 1,000.

The copolymer is preferably an acrylic polymer including at least one of a carboxyl group-containing monomer and a hydroxyl group-containing nitrogen-containing vinyl monomer as another copolymerizable monomer group.

Examples of the (A) alkyl (meth) acrylate monomer having C4 to C18 carbon atoms include butyl (meth) acrylate, isobutyl (meth) acrylate, and (meth) acrylic acid Amyl ester, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (formyl) (Nonyl) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, twelve (meth) acrylate Alkyl ester, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, cetyl (meth) acrylate, (formyl) Base) heptadecyl acrylate, octadecyl (meth) acrylate, myristyl (meth) acrylate, isotetradecyl (meth) acrylate, cetyl (meth) acrylate, Isohexadecyl (meth) acrylate, stearyl (meth) acrylate, (meth) acrylic acid Octadecyl acrylate and the like.
The content of the (A) alkyl (meth) acrylate monomer having C4 to C18 alkyl groups is preferably 50 to 98 parts by weight based on 100 parts by weight of the copolymer.

Examples of the (B) hydroxyl-containing copolymerizable monomer include 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, ( Hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl methacrylate; N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl Hydroxyl-containing (meth) acrylamide and the like such as (meth) acrylamide.
The above-mentioned hydroxyl-containing copolymerizable monomer is preferably selected from the group consisting of 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, ( Compound consisting of 2-hydroxyethyl methacrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide At least one or more of the group.
The content of the hydroxyl group-containing copolymerizable monomer (B) is preferably 0.1 to 10 parts by weight based on 100 parts by weight of the copolymer.

For the aforementioned copolymers, it can also be used as other copolymerizable monomer groups including carboxyl-containing monomers, hydroxyl-free nitrogen-containing vinyl monomers, and polyalkylene glycol mono (meth) acrylate monomers. At least one of them.

The aforementioned carboxyl group-containing monomer is preferably selected from the group consisting of (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, and 2- (meth) acryloxyethyl Hexahydrophthalic acid, 2- (meth) acryloxypropyl hexahydrophthalic acid, 2- (meth) acryloxyethyl phthalic acid, 2- (meth) propylene Ethoxyethyl succinic acid, 2- (meth) acryl ethoxyethylmaleic acid, carboxy polycaprolactone mono (meth) acrylate, 2- (meth) acryl ethoxyethyl tetra At least one or more of the compound group consisting of hydrogen phthalic acid.
When the aforementioned copolymer includes a carboxyl group-containing monomer as another copolymerizable monomer group, the content of the carboxyl group-containing monomer is preferably 0.1 to 1.0 part by weight based on 100 parts by weight of the aforementioned copolymer. The copolymer may not contain the carboxyl group-containing monomer.

As said polyalkylene glycol mono (meth) acrylate monomer, what is necessary is just a compound in which one of the several hydroxyl groups which a polyalkylene glycol has is esterified into a (meth) acrylate. . Since the (meth) acrylate group is a polymerizable group, it can be copolymerized with a copolymer of a main agent. The other hydroxyl group may be in the state of OH, may be an alkyl ether such as methyl ether and diethyl ether, or may be a saturated carboxylic acid ester such as acetate.
Examples of the alkylene group contained in the polyalkylene glycol include, but are not limited to, ethylene (vinyl), propylene (propenyl), butylene (butenyl) and the like. 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 polyalkylene glycol copolymer 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.
The average number of repeats of alkylene oxide constituting the polyalkylene glycol chain in the polyalkylene glycol mono (meth) acrylate monomer is preferably from 3 to 14. The "average repeating number of alkylene oxides" refers to the alkylene oxides in the "polyalkylene glycol chain" part contained in the molecular structure of the aforementioned polyalkylene glycol mono (meth) acrylate monomer. The average number of unit repeats.

The polyalkylene glycol mono (meth) acrylate monomer is preferably selected from the group consisting of polyalkylene glycol mono (meth) acrylate and methoxy polyalkylene glycol (methyl). At least one or more of acrylate and ethoxy polyalkylene glycol (meth) acrylate.
More specific examples include polyethylene glycol-mono (meth) acrylate, polypropylene glycol-mono (meth) acrylate, polybutylene glycol-mono (meth) acrylate, and 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; methoxy polyethylene glycol- (meth) acrylate, methoxy polypropylene glycol- (meth) acrylate, methoxy polybutylene Glycol- (meth) acrylate, methoxy-polyethylene glycol-polypropylene glycol- (meth) acrylate, methoxy-polyethylene glycol-polybutylene glycol- (meth) acrylate, Methoxy-polypropylene glycol-polybutylene glycol- (meth) acrylate, methoxy-polyethylene glycol-polypropylene glycol-polybutylene glycol- (meth) acrylate; ethoxy polyethylene glycol -(Meth) acrylate, ethoxy polypropylene glycol- (meth) acrylate, ethoxy polybutylene glycol- (meth) acrylate, ethoxy-polyethylene glycol-polypropylene glycol- (methyl Based) acrylate, ethoxy-polyethylene glycol-polybutylene glycol- (meth) acrylate, ethoxy-polypropylene glycol-polybutylene glycol- (meth) acrylate, ethoxy-poly Ethylene glycol-polypropylene glycol-polybutylene glycol- (meth) acrylate.
The content of the polyalkylene glycol mono (meth) acrylate monomer is preferably 0 to 50 parts by weight based on 100 parts by weight of the copolymer. The copolymer may not include the polyalkylene glycol mono (meth) acrylate monomer.

Examples of the vinyl monomer containing no hydroxyl group and containing nitrogen include a vinyl monomer containing a amide bond, a vinyl monomer containing an amino group, and a vinyl monomer having a nitrogen-containing heterocyclic structure. More specifically, N-vinyl-2-pyrrolidone, N-vinylpyrrolidone, methylvinylpyrrolidone, N-vinylpyridine, N-vinylpyridone, N-vinylpyrimidine, N-vinylpyrazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N -Cyclic nitrogen vinyl compounds having N-vinyl substituted heterocyclic structures such as vinyl dodecylamine; N- (meth) acrylfluorenylmorpholine, N- (meth) acrylfluorenylfluorene Azine, N- (meth) propenylaziridine, N- (meth) propenylaziridine, N- (meth) propenylpyrrolidine, N- (meth) propenylpyrrolyl A pyridine, N- (meth) acrylfluorenylazacycloheptane, N- (meth) acrylfluorenylazacyclooctane, and the like having a heterocyclic structure substituted with N- (meth) acrylfluorenyl Cyclic nitrogen vinyl compounds; N-cyclohexyl maleimide, N-phenyl maleimide, and other cyclic nitrogen vinyls having a heterocyclic structure containing a nitrogen atom and a vinyl unsaturated bond in the ring Base compound; (methyl) Unsubstituted or mono-alkyl substituted such as alleneamine, N-methyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-tert-butyl (meth) acrylamide (Meth) acrylamide; 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-formyl Dialkyl-substituted (meth) acrylamide, such as N-propyl- (meth) acrylamide, N-methyl-N-isopropyl (meth) acrylamide; N, N-dimethylformamide Amino aminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-di Methylaminoisopropyl (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-propylamino (Meth) acrylate, N-methyl-N-isopropylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, tert-butylaminoethyl Dialkylamino (meth) acrylates such as methyl (meth) acrylate; N, N-dimethylaminopropyl (meth) acrylamidonium, N, N-diethylaminopropyl (methyl ) Acrylamide, N, N-dipropylaminopropyl (meth) acrylamide, N, N-diisopropylaminopropyl (meth) acrylamide, N-ethyl-N-formyl Aminopropyl (meth) acrylamide, N-methyl-N-propylaminopropyl (meth) acrylamide, N-methyl-N-isopropylaminopropyl (meth) acryl N, N-dialkyl-substituted aminopropyl (meth) acrylamide, such as amidine; N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide N-vinyl carboxylic acid amidines such as amines; N-methoxymethyl (meth) acrylamide, N-ethoxyethyl (meth) acrylamide, N-butoxymethyl ( (Meth) acrylamide, diacetoneacrylamide, N, N-methylenebis (meth) acrylamide, etc. Amine; (meth) acrylonitrile, unsaturated carboxylic acid nitriles and the like; and the like.

The content of the vinyl monomer containing no hydroxyl group and containing nitrogen is preferably 0 to 20 parts by weight based on 100 parts by weight of the copolymer. The said copolymer may not contain the said vinyl monomer which does not contain the said hydroxyl group, and contains nitrogen.

The (C) difunctional or higher isocyanate compound may be at least one kind or two or more kinds selected from polyisocyanate compounds having at least two isocyanate (NCO) groups in one molecule. Polyisocyanate compounds include classifications of aliphatic isocyanates, aromatic isocyanates, acyclic isocyanates, and alicyclic isocyanates, and the present invention may be any of them. 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), xylylene diisocyanate (XDI), hydrogenated xylylene diisocyanate (H6XDI), dimethyldiphenylene diisocyanate (TOID), toluene diisocyanate (TDI ) And other aromatic isocyanate compounds.
Examples of the trifunctional or higher isocyanate compound include biuret-modified or isocyanurate-modified bifunctional isocyanate compounds (compounds having two NCO groups in one molecule), and trimethylol. Adducts (polyol modified products) of trivalent or higher polyhydric alcohols (compounds having at least three or more OH groups in one molecule) such as propane (TMP) or glycerol.
As the (C) difunctional or higher isocyanate compound, only (C-1) a trifunctional isocyanate compound or only (C-2) a difunctional isocyanate compound may be used. In addition, (C-1) a trifunctional isocyanate compound and (C-2) a difunctional isocyanate compound may be used in combination.

The (C-1) trifunctional isocyanate compound used in the present invention preferably includes at least one or more selected from the group of (C-1-1) first aliphatic isocyanate compounds and is selected from (C- 1-2) At least one or more of the second aromatic isocyanate compound group, wherein the (C-1-1) first aliphatic isocyanate compound group is an isocyanuric compound composed of a hexamethylene diisocyanate compound Acid ester, isocyanurate diisocyanate compound, isocyanurate, adduct of hexamethylene diisocyanate compound, adduct of isophorone diisocyanate compound, condensation of hexamethylene diisocyanate compound Diurea, biuret of isophorone diisocyanate compound; the (C-1-2) second aromatic isocyanate compound group is made of toluene diisocyanate compound, isocyanurate, xylylene Diisocyanate compound isocyanurate, hydrogenated xylylene diisocyanate compound isocyanurate, toluene diisocyanate compound adduct, xylylene diisocyanate compound adduct, Adduct of xylylene diisocyanate compound composed. It is preferable to use (C-1-1) the first aliphatic isocyanate compound group and (C-1-2) the second aromatic isocyanate compound group in combination. In the present invention, as the (C-1) trifunctional isocyanate compound, at least one or more selected from the (C-1-1) first aliphatic isocyanate compound group is used in combination and selected from (C-1-2) At least one or more of the second aromatic isocyanate compound group can further improve the balance of the adhesive force in the low-speed peeling region and the high-speed peeling region.
In addition, it is preferable that the (C-1) trifunctional isocyanate compound contains at least one kind or more selected from the aforementioned (C-1-1) first aliphatic isocyanate compound group and is selected from the aforementioned (C-1-2) At least one or more of the diaromatic isocyanate compound group has a total amount of 0.5 to 5.0 parts by weight based on 100 parts by weight of the copolymer. In addition, as a mixture of at least one or more selected from the (C-1-1) first aliphatic isocyanate compound group and at least one or more selected from the (C-1-2) second aromatic isocyanate compound group The ratio is preferably calculated as a weight ratio (C-1-1): (C-1-2) within a range of 10%: 90% to 90%: 10%.

The (C-2) difunctional isocyanate compound used in the present invention is preferably an acyclic aliphatic isocyanate compound and a compound formed by a reaction between a diisocyanate compound and 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 by the general formula "HO-Y-OH" (where Y is a divalent group) When the diol compound represents a diol compound, examples of the compound produced by the reaction between the diisocyanate compound and the diol compound include compounds represented by the following general formula Z.

[Formula 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 general formula Z is expressed as "O = C = N-X-N = C = O". The difunctional acyclic aliphatic isocyanate compound may include a compound in which n is 0 in the general formula Z (a diisocyanate compound that is not reacted with respect to a diol compound), and a compound containing n as an integer of 1 or more as an essential component is preferable. . The bifunctional acyclic aliphatic isocyanate compound may be a mixture composed of a plurality of compounds in which n in Formula Z is different.

The diisocyanate compound represented by the general formula "O = C = N-X-N = C = O" is an aliphatic diisocyanate. X is preferably an acyclic aliphatic divalent group. The aliphatic diisocyanate is preferably selected from the group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate. One or two or more of the compounds of the isocyanate group are constituted.

The diol compound represented by the general formula "HO-Y-OH" is an aliphatic diol. Y is preferably an acyclic aliphatic divalent group. The diol compound is preferably selected from the group consisting of 2-methyl 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, and 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 monohydroxyneopent It is composed of one or two or more compounds in a compound group consisting of an acid ester, polyethylene glycol, and polypropylene glycol.

The weight ratio (C-1 / C-2) of the (C-1) trifunctional isocyanate compound to the (C-2) difunctional isocyanate compound is preferably 1 to 90. The said (C) bifunctional or more isocyanate compound is 0.1-10 weight part with respect to 100 weight part of said copolymers.

When a polyisocyanate compound is used as the crosslinking agent, the crosslinking catalyst of the (D) metal chelate may be any substance that can function as a catalyst and that can react with the copolymer (crosslinking reaction) and the crosslinking agent. Examples include amine compounds such as tertiary amines, metal chelates, organic tin compounds, organic lead compounds, and organic zinc compounds. In the present invention, a metal chelate is used as the crosslinking catalyst.

A metal chelate is a compound in which one or more polydentate ligands L are bonded to a central metal atom M. The metal chelate may or may not have one or more monodentate ligands X bonded to the metal atom M. For example, when the general formula of a metal chelate having one metal atom M is represented by M (L) _m (X) _n , m _≧ 1 and _{n ≧ 0} . When m is 2 or more, m Ls may be the same ligand or different ligands. When n is 2 or more, n X 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 multidentate ligand L include methyl ethyl acetate, ethyl ethyl acetate, ethyl ethyl acetate, oleyl ethyl acetate, lauryl ethyl acetate, stearyl ethyl acetate, and the like. beta] - keto ester; Acetylacetonates: β (alias 2,4-pentanedione), 2,4-hexanedione, benzoyl acetone, etc. - dione. These are keto-enol tautomers, and in the multidentate ligand L, they may be enolates (for example, acetamidine acetonate) obtained by deprotonating the enol.
Examples of the monodentate ligand X include a halogen atom such as a chlorine atom and a bromine atom, pentamyl, hexyl, 2-ethylhexyl, octyl, nonyl, decyl, sulfonyl, Alkoxy groups such as stearyl, and alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, and butoxy.

Specific examples of the metal chelate include tris (2,4-pentanedione) iron (III), iron triacetamone acetone, titanium triacetamone acetone, titanium triacetamone ruthenium acetone, and diacetamone acetone. Zinc, aluminum triacetamate, zirconium tetraacetamone, tris (2,4-hexadione) iron (III), zinc (bis, 2,4-hexadione), tris (2,4-hexadione) ) Titanium, tris (2,4-hexadione) aluminum, tetras (2,4-hexadione) zirconium and the like.

Examples of the organic tin compound include dialkyltin oxides, fatty acid salts of dialkyltin, and fatty acid salts of stannous acids. In the past, dibutyltin compounds have been used in most cases, but in recent years, the toxicity of organic tin compounds has been pointed out. In particular, tributyltin (TBT) contained in dibutyltin compounds is also a cause of concern. From the viewpoint of safety, a long-chain alkyltin compound such as a dioctyltin compound is preferred. Specific examples of the organic tin compound include dioctyltin oxide and dioctyltin dilaurate. Although a Sn compound can also be used temporarily, in view of the tendency to use a more safe substance in the future, it is preferable to use a metal chelate such as Al, Ti, Fe, etc., which is safer than Sn.
The metal chelate in the binder composition of the present invention preferably contains at least one or more members selected from the group consisting of an aluminum chelate, a titanium chelate, and an iron chelate.
The content of the crosslinking catalyst of the metal chelate (D) is preferably 0.001 to 0.5 parts by weight based on 100 parts by weight of the copolymer.

Examples of (E) keto-enol tautomer compounds include methyl ethyl acetate, ethyl ethyl acetate, octyl ethyl acetate, oleyl ethyl acetate, lauryl ethyl acetate, and ethyl ethyl acetate Β -ketoesters such as stearyl acetate; β -diketones such as acetone, 2,4-hexanedione, and benzophenone. In a binder composition using a polyisocyanate compound as a cross-linking agent, by blocking the isocyanate group of the cross-linking agent, the viscosity of the binder composition can be prevented from increasing excessively or gelling after the cross-linking agent is formulated. This phenomenon can extend the shelf life of the adhesive composition.
The content of the (E) keto-enol tautomer compound is preferably 0.1 to 300 parts by weight based on 100 parts by weight of the copolymer.

In contrast to (D) a metal chelate cross-linking catalyst, (E) a keto-enol tautomer compound has an effect of inhibiting cross-linking. Therefore, it is preferable to appropriately set (E) a keto-enol tautomer The ratio of the structure compound to the crosslinking catalyst of (D) metal chelate. In order to extend the shelf life of the binder composition and improve storage stability, the weight ratio (E) / of a cross-linking catalyst for (E) a keto-enol tautomer compound / (D) metal chelate compound is preferably (E) / (D) is high. The value of (E) / (D) is preferably in the range of 70 to 1,000, more preferably 70 to 800, and most preferably 80 to 600.

The adhesive composition having a prolonged storage period based on the present invention, more specifically, it is preferable that the adhesive composition is stored at 23 ° C. and has a viscosity lower than that of the adhesive composition after 8 hours. 1.25 times the viscosity after blending. This makes it possible to obtain a binder composition in which viscosity increase after preparation is suppressed.

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

Examples of the antistatic agent include an antistatic agent contained in a binder composition and an antistatic agent copolymerized in the copolymer. The content of the antistatic agent is preferably 0.05 to 5.0 parts by weight based on 100 parts by weight of the copolymer.
The antistatic agent has a melting point of 25 ° C. to 50 ° C., and is preferably an ionic compound that is solid at a temperature of 25 ° C. and / or an ionic compound containing an acrylic fluorenyl group. Since these antistatic agents have a low melting point and have a long-chain alkyl group, it is presumed that they have high affinity with acrylic copolymers.

The ionic compound having a melting point of 25 to 50 ° C is an ionic compound having a cation and an anion. Examples of the ionic compound include a pyridinium cation, an imidazolium cation, a pyrimidinium cation, a pyrazolium cation, a pyrrolium cation, and ammonium nitrogen-containing cation cation, or phosphonium cation, sulfonium cation, the anion is hexafluorophosphate (PF ₆ ^-), thiocyanate (SCN ^-), alkylbenzene sulphonate ^{_{(RC 6 H 4 SO 3 -}} ) , perchlorate (ClO ^4-), tetrafluoroborate (BF ₄ ^-), bis (fluorosulfonyl acyl) (PEI) root (FSI), bis (trifluoromethanesulfonyl acyl) (PEI) root (TFSI ), Trifluoromethanesulfonate (TF) and other inorganic or organic anionic compounds. The compound is preferably solid at normal temperature (for example, 25 ° C), and a compound having a melting point of 25 to 50 ° C can be obtained by selecting the chain length of the alkyl group, the position and number of substituents, and the like. The cation is preferably a quaternary azinium cation, and examples thereof include quaternary pyridinium cations such as 1-alkylpyridinium (the carbon atom at the 2 to 6 position may or may not have a substituent), 1,3 -Quaternary imidazolium cations such as dialkylimidazolium (carbon atoms at the 2, 4, and 5 positions may or may not have a substituent), quaternary ammonium cations such as tetraalkylammonium, and the like.
The content of the ionic compound having a melting point of 25 to 50 ° C. is preferably 0.05 to 5 parts by weight based on 100 parts by weight of the copolymer.

Examples of the propylene compound containing an acrylofluorenyl group are ionic compounds having a cation and an anion. Examples of the ionic compound include a (meth) acryloxyalkyltrialkylammonium (R ₃ N ⁺ -C _n H _2n -OCOCQ) = CH _2, where, Q = H or CH _3, R = alkyl) or the like containing the cationic (meth) Bingxi Xi group; phosphate hexafluoride anion (PF ₆ ^-), thiocyanate (SCN ^- ), organic sulfonate (RSO ₃ ^-), perchlorate (ClO ₄ ^-), borate tetrafluoride (BF ₄ ^-), (PEI) containing the F root (R ^F ₂ N ^-) and the like inorganic or organic Anionic compounds. (PEI) containing a root of F (R ^F ₂ N ^-) of R & lt ^F, include trifluoromethanesulfonic acyl, sulfo pentafluoroethyl acyl group such as a perfluoroalkyl sulfonic acyl, sulfo-fluoro-acyl. (PEI) containing F as the root include bis (fluorosulfonyl acyl) (PEI) root [(FSO _{2) 2} N ^-], bis (trifluoromethanesulfonyl acyl) (PEI) root [(CF ₃ SO _{2) 2} N ^-], bis (pentafluoroethane sulfonyl acyl) (PEI) root _{[(C 2 F 5 SO 2)} 2 N - etc.] bis sulfo acyl (PEI) root.
It is preferable that the copolymerization amount of the propylene compound containing an propylene group in the copolymer is 0.1 to 5.0% by weight.

Specific examples of the antistatic agent are not particularly limited, but specific examples of the ionic compound having a melting point of 25 to 50 ° C include 1-octylpyridinium hexafluorophosphate and 1-nonylpyridinium hexafluorophosphate Salt, 2-methyl-1-dodecylpyridinium hexafluorophosphate, 1-octylpyridinium dodecylbenzenesulfonate, 1-dodecylpyridinium thiocyanate, 1- Dodecylpyridinium dodecylbenzenesulfonate, 4-methyl-1-octylpyridinium hexafluorophosphate, quaternary ammonium salt of trifluoromethanesulfonic acid, and the like. In addition, as a specific example of the ionic compound containing acrylfluorenyl group, methyl dimethylamino (meth) acrylate hexafluorophosphate methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ = CH ₂ • PF ₆ ^- where, Q = H or CH _3], dimethylamino (meth) acrylate bis (trifluoromethanesulfonyl acyl) methyl acyl imide salt ^{_{[(CH 3) 3 N + (}} CH 2) ₂ OCOCQ = CH ₂ • (CF ₃ SO ₂ ) ₂ N ⁻ , where Q = H or CH ₃ ], dimethylaminomethyl methacrylate bis (fluorosulfonyl) phosphonium imine methyl salt [(CH ₃ ) ₃ N ⁺ CH ₂ OCOCQ = CH ₂ • (FSO ₂ ) ₂ N ⁻ , where Q = H or CH ₃ ] and the like.

The aforementioned polyether-modified silicone compound is a silicone compound having a polyether group, and has a silicone unit containing a polyether group in addition to a normal silicone unit (-SiR ¹ ₂ -O-). (-SiR ¹ (R ² O (R ³ O) _n R ⁴ ) -O-). Here, R ¹ represents one or two or more alkyl or aryl groups, R ² and R ³ represent one or two or more alkylene groups, R ⁴ represents one or two or more alkyl groups, fluorenyl groups, and the like ( Terminal group). Examples of the polyether group include polyoxyalkylene groups such as a polyoxyethylene group ((C ₂ H ₄ O) _n ) and a polyoxypropylene group ((C ₃ H ₆ O) _n ).
The polyether-modified silicone compound is preferably a polyether-modified silicone compound having an HLB value of 7 to 15. Moreover, it is preferable that content of the said polyether modified silicone compound with respect to 100 weight part of copolymers is 0.01-1.0 weight part. More preferably, it is 0.1 to 0.5 parts by weight.
HLB refers to a predetermined hydrophilic-lipophilic balance (a ratio of hydrophilicity to lipophilicity) specified in JIS K3211 (surfactant term).
The aforementioned polyether-modified siloxane compound can be obtained, for example, by a method of grafting an organic compound having an unsaturated bond and a polyoxyalkylene group to a polyorganosiloxane having a silane group by a hydrosilylation reaction. Obtained from the main chain. Specific examples include a dimethylsiloxane-methyl (polyoxyethylene) siloxane copolymer, a dimethylsiloxane-methyl (polyoxyethylene) siloxane-methyl (poly (ethylene oxide)) (Propylene oxide) silicone copolymer, dimethylsilane-methyl (polyoxypropylene) silicone copolymer, etc.
By blending the aforementioned polyether-modified silicone compound in an adhesive composition, the adhesive force and reworkability of the adhesive can be improved. When the adhesive composition does not contain a polyether-modified silicone compound, the cost can be made lower.

Examples of the antioxidant include hindered phenol-based antioxidants, polyphenol compounds, and tocopherol-based compounds. Among them, tocopherols are preferred. Tocopherols are usually vitamin E, which is also derived from natural chemicals. As a result, it has fewer adverse effects on the human body, high safety in use, and no pollution to the environment. In addition, since it is oil-soluble and liquid at normal temperature, it is also excellent in compatibility with the adhesive composition and precipitation resistance. By blending the tocopherol compound as the antioxidant, the storage stability of the binder is improved, and therefore the shelf life of the binder composition containing the curing agent is improved.
As the tocopherol compound to be used in the present invention, it is preferred that the tocopherol compound contains a phenolic hydroxyl group without being converted into an ester or the like from the viewpoint of using it in an adhesive composition (which does not undergo metabolism as in the human body). compound of. Examples include tocopherol and tocotrienol. It is known that tocopherols and tocotrienols have a difference between a natural compound (d-body), an unnatural compound (l-body), a racemic body (dl-body) of an equivalent mixture thereof, and the like. Natural compounds (d-body) and racemic body (dl-body) are preferred because they can also be used as food additives.
Specific examples of tocopherol compounds include compounds selected from the group 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, d- δ -tocotrienol, dl- δ -tocotrienol One. Two or more tocopherol compounds may be used in combination. Substances known as "mixed tocopherol" as food additives contain d- α -tocopherol, d- β -tocopherol, d- γ -tocopherol, and d- δ -tocopherol as main ingredients A mixture known as "tocotrienols", which is based on d- α -tocotrienol, d- β -tocotrienol, d- γ -tocotrienol, and d- δ -tocotrienol. Enol is a mixture of main ingredients.
When the adhesive composition of the present invention contains a tocopherol compound, the content of the tocopherol compound is preferably 0.01 to 5 parts by weight based on 100 parts by weight of the copolymer.

In addition, as other components, a copolymerizable (meth) acrylic acid monomer containing an alkylene oxide, a (meth) acrylamide monomer, a dialkyl-substituted acrylamide monomer, Surfactants, curing catalysts, plasticizers, fillers, curing inhibitors, processing aids, anti-aging agents, antioxidants and other conventional additives. These may be used alone or in combination of two or more.

As the copolymer of the main agent used in the adhesive composition of the present invention, at least one of (A) alkyl (meth) acrylate monomers having C4 to C18 carbon atoms can be used as a copolymerizable monomer (B) a hydroxyl group-containing copolymerizable monomer is copolymerized and synthesized. The polymerization method of the copolymer is not particularly limited, and an appropriate polymerization method such as solution polymerization or emulsion polymerization can be used.
In addition, as for the said copolymer, it is preferable that it is a copolymerizable monomer group which can contain at least 1 or more types of a carboxyl group-containing monomer, a hydroxyl group-free, and a nitrogen-containing vinyl monomer.
The binder composition of the present invention can be prepared by blending (C) a bifunctional or higher isocyanate compound, (D) a metal chelate cross-linking catalyst, and (E) a keto-enol tautomer compound in the copolymer. And any appropriate additives to formulate.

The copolymer is preferably an acrylic polymer, and preferably contains 50 to 100% by weight of a (meth) acrylic acid ester monomer or an acrylic monomer such as (meth) acrylic acid or (meth) acrylamide.
The acid value of the copolymer is preferably 8.0 or less, and more preferably 0.01 to 8.0. Thereby, it is possible to improve the contamination property and the performance of preventing the occurrence of the adhesive residue phenomenon.
Here, the "acid value" is one of the indicators showing the acid content, and is expressed in mg of potassium hydroxide required to neutralize 1 g of a polymer containing a carboxyl group.

It is preferable that the adhesive force of the adhesive layer formed by crosslinking the aforementioned adhesive composition at a low peeling speed of 0.3 m / min is 0.05 to 0.2 N / 25 mm, and the adhesive force at a high peeling speed of 30 m / min is 2.0. N / 25mm or less. As a result, a small change in the adhesive force with the peeling speed can be obtained, and the peeling can be performed quickly even in the case of high-speed peeling. In addition, even when the surface protection film is temporarily peeled for re-adhesion, an excessive force is not required, and it is easy to peel from the adherend.

The gel fraction of the adhesive layer (crosslinked adhesive) obtained by crosslinking the adhesive composition of the present invention is preferably 90 to 100%. Because the gel fraction is so high, the adhesive force will not become too large at low peel speeds, reducing the phenomenon of dissolution of unpolymerized monomers or oligomers from the copolymer, which can improve reworkability, high temperature / high Durability under wet conditions and suppresses contamination by adherends.

The adhesive film of the present invention is formed by forming an adhesive layer on one or both sides of a resin film, and the adhesive layer is formed by crosslinking the adhesive composition of the present invention. In addition, the surface protection film of the present invention is formed by forming an adhesive layer on one side of a resin film, and the adhesive layer is formed by crosslinking the adhesive composition of the present invention. Since the adhesive composition of the present invention blends each of the components (A) to (E) with a good balance, the storage period is long and the crosslinking speed is long without using an organotin compound. Also fast. Therefore, the surface protection film of the present invention can be suitably used as a surface protection film of a polarizing plate, or it can be selected from a precision electrical circuit consisting of a flexible printed circuit board, a rigid printed circuit board, and a transparent conductive film. The surface protective film of any of the precision electrical / electronic components in the / electronic component group is suitably used.

Among the adhesive film and surface protective film of the present invention, a polyester film or the like can be used as a base material of a resin film or a release film (separator) that protects an adhesive layer.
In addition, the resin film may be formed on the surface of the resin film opposite to the side where the adhesive layer is formed by using a silicone-based, fluorine-based release agent or coating agent, or silica particles. The antifouling treatment may be an antistatic treatment by applying or mixing an antistatic agent.
In addition, the release film is subjected to a release treatment with a silicone-based, fluorine-based release agent, or the like on the surface to be bonded to the adhesive surface of the adhesive layer.
[Example]

Hereinafter, the present invention will be specifically described based on examples.

<Production of acrylic copolymer>
[Example 1]
Nitrogen was introduced into a reaction device equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, thereby replacing the air in the reaction device with nitrogen. Then, 100 parts by weight of 2-ethylhexyl acrylate and 3.5 parts by weight of 8-hydroxyoctyl acrylate were added to the reaction apparatus. Then, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise over 2 hours, and the mixture was reacted at 65 ° C for 6 hours to obtain acrylic acid used in Example 1 with a weight average molecular weight of 500,000. Copolymer Solution 1. A part of the acrylic copolymer was taken and used as an acid value measurement sample described later.
[Examples 2 to 6 and Comparative Examples 1 to 3]
Except that the composition of each monomer was adjusted as described in (A), (B), and (I) in Table 1, the same operation as in the above-mentioned acrylic copolymer solution 1 used in Example 1 was performed to obtain The acrylic copolymer solution used in Examples 2 to 6 and Comparative Examples 1 to 3.

<Manufacture of an adhesive composition and a surface protection film>
[Example 1]
To the acrylic copolymer solution 1 of Example 1 produced as described above, 6.0 parts by weight of acetone and acetone were added, and then 1.5 parts by weight of Coronate HX (colroto HX, hexamethylene diisocyanate compound isocyanate) was added. Uric acid ester) and 0.05 parts by weight of tris (2,4-pentanedione) iron (III), and then mixed by stirring to obtain the adhesive composition of Example 1. This adhesive composition was coated on a release film composed of a silicone resin-coated polyethylene terephthalate (PET) film, and then dried at 90 ° C to remove the solvent to obtain an adhesive layer. An adhesive sheet having a thickness of 25 μm.
Then, prepare a polyethylene terephthalate (PET) film with antistatic treatment and antifouling treatment on one surface, and transfer the adhesive sheet to the polyethylene terephthalate (PET) On the side of the film opposite to the side subjected to the antistatic treatment and the antifouling treatment, a PET film with an antistatic treatment and an antifouling treatment, an adhesive layer, and a release film (PET coated with silicone resin) was obtained. Film) ". The surface protection film of Example 1 having a laminated structure.
[Examples 2 to 6 and Comparative Examples 1 to 3]
Except that the composition of each additive was set as described in Tables (C) to (E), the surface protection film of Example 1 was operated in the same manner as described above to obtain surface protection of Examples 2 to 6 and Comparative Examples 1 to 3. membrane.

[Table 1]

In Table 1, the numerical values in parentheses represent numerical values of parts by weight obtained by setting the total weight of the group (A) to 100 parts by weight. The ratio of (E) / (D) is shown in Table 2. In addition, the compound names corresponding to the abbreviations of the respective components used in Table 1 are shown in Table 3. In addition, Coronate (registered trademark) HX, Coronate HL and Coronate L are trade names of Nippon Polyurethane Industry Co., Ltd .; Takenate (registered trademark) D-140N is a trademark of Mitsui Chemicals Co., Ltd. Trade name; DURANATE (registered trademark) D101 is a trade name of Asahi Kasei Chemicals Corporation.

[Table 2]

[table 3]

＜ Test method and evaluation ＞
After the surface protection films of Examples 1 to 6 and Comparative Examples 1 to 3 were aged at 23 ° C and 50% RH for 7 days, the release film (a PET film coated with a silicone resin) was peeled off to cause adhesion. The agent layer is exposed. Furthermore, the exposed surface protective film of the adhesive layer was bonded to the surface of the polarizing plate pasted on the liquid crystal cell through the adhesive layer, and after being left for 1 day, it was subjected to autoclave treatment at 50 ° C and 5 atmospheres for 20 minutes. It was left at room temperature for 12 hours, and the surface protection film thus obtained was used as a sample for measuring the adhesive force.

＜ Adhesiveness ＞
A tensile tester was used to peel the measurement sample obtained above at a low peel speed (0.3 m / min) and a high peel speed (30 m / min) in a direction of 180 ° (a 25 mm wide surface protective film was bonded to polarized light A sample formed on the surface of a plate), the peel strength was measured, and the peel strength was used as the adhesive force.

＜ Storage period ＞
The viscosity of the adhesive composition η ₀ (initial viscosity) was measured immediately after the additives (C) to (E) were formulated, and the viscosity of the adhesive composition was measured after the adhesive composition was left at 23 ° C for 8 hours in a sealed state. η ₁ (viscosity after 8 hours). As an index of the storage period, a value of η ₁ when η ₀ was 1.0, that is, a ratio of η ₁ / η ₀ was determined. The evaluation target criteria are as follows: when the viscosity after 8 hours is less than 1.25 times the initial viscosity, it is evaluated as "○", when it is 1.25 times or more and less than 1.50 times, it is evaluated as "△", and it is 1.50 times or more or left for 8 hours When gelation occurred, it was evaluated as "x".

The evaluation results are shown in Table 4.

[Table 4]

For the surface protective films of Examples 1 to 6, the adhesive force at a low peeling speed of 0.3 m / min is 0.05 to 0.2 N / 25 mm, and the adhesive force at a high peeling speed of 30 m / min is 2.0 N / 25 mm or less. The storage period is also long enough.
That is, the balance of the adhesive force is excellent at a low peeling speed and a high peeling speed, the storage period is long, and the characteristics as a surface protective film are also excellent.
In addition, the surface protection films of Examples 1 to 6 have high safety because the adhesive composition does not contain an organic tin compound.

The surface protective film of Comparative Example 1 may be because it does not contain a (C) difunctional or higher isocyanate compound as a crosslinking agent, and has a low peeling speed of 0.3 m / min and a high peeling speed of 30 m / min. Is too strong.
The surface protection film of Comparative Example 2 had a short storage period because the ratio of the (E) keto-enol tautomer compound to the (D) metal chelate cross-linking catalyst was small.
The surface protection film of Comparative Example 3 may be because the ratio of the (E) keto-enol tautomer compound to the (D) metal chelate cross-linking catalyst is small, and its storage period becomes too short. Since the cross-linking has been performed before coating, coating cannot be performed.
As described above, the surface protective films of Comparative Examples 1 to 3 cannot satisfy all of the performance requirements such as excellent balance of adhesion at low peel speed and high peel speed, and long storage life.

no.

no.

Claims (10)

An adhesive composition is an adhesive composition comprising an acrylic polymer and a cross-linking agent, wherein: The acrylic polymer is a copolymerizable (at least one of (A) alkyl (meth) acrylate monomers having C4 to C18 alkyl groups and (B) a hydroxyl group-containing copolymerizable copolymer group). Copolymers of monomers, The binder composition contains, based on 100 parts by weight of the copolymer, 0.1 to 10 parts by weight of (C) a bifunctional or higher isocyanate compound as the crosslinking agent, and (D) a metal chelate cross-linking catalyst 0.001. ～ 0.5 parts by weight and (E) keto-enol tautomer compound 0.1-300 parts by weight, and the ratio of (E) / (D) by weight is 70-1000, Tocopherols as antioxidants, and The crosslinking catalyst does not include an organotin compound. The adhesive composition according to item 1 of the scope of patent application, wherein the viscosity of the adhesive composition after storage of the adhesive composition at 23 ° C. for 8 hours is lower than that immediately after the formulation 1.25 times the viscosity. The adhesive composition according to item 1 or 2 of the scope of patent application, wherein the (B) hydroxyl-containing copolymerizable monomer is selected from the group consisting of 8-hydroxyoctyl (meth) acrylate, (methyl) ) 6-hydroxyhexyl acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (methyl) At least one or more of a compound group consisting of acrylamide and N-hydroxyethyl (meth) acrylamide. The adhesive composition according to item 1 or 2 of the scope of patent application, wherein: In the above-mentioned (C) difunctional isocyanate compound, the difunctional isocyanate compound is an acyclic aliphatic isocyanate compound and is a compound formed by the reaction of a diisocyanate compound and a diol compound, The diisocyanate compound is an aliphatic diisocyanate, and is selected from the group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine. One of a group of compounds consisting of diisocyanates, The diol compound is selected from the group 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, poly One of the compound groups consisting of ethylene glycol and polypropylene glycol, The trifunctional isocyanate compound is isocyanurate of hexamethylene diisocyanate compound, isocyanurate of isophorone diisocyanate compound, adduct of hexamethylene diisocyanate compound, isophorone Adduct of diisocyanate compound, biuret of hexamethylene diisocyanate compound, biuret of isophorone diisocyanate compound, isocyanurate of toluene diisocyanate compound, xylylene diisocyanate compound Isocyanurate, isocyanurate of hydrogenated xylylene diisocyanate compound, adduct of toluene diisocyanate compound, adduct of xylylene diisocyanate compound, hydrogenated xylylene diisocyanate Adducts of compounds. The adhesive composition according to item 1 or 2 of the scope of the patent application, wherein the copolymer is a group of other copolymerizable monomers including a carboxyl group-containing monomer and a hydroxyl group-free nitrogen-containing vinyl monomer. Of at least one acrylic polymer. The adhesive composition according to item 1 or 2 of the patent application scope, wherein the gel fraction of the adhesive composition after cross-linking is 90 to 100%. An adhesive film is formed by forming an adhesive layer on one or both sides of a resin film. The adhesive layer crosslinks the adhesive composition according to any one of claims 1 to 6 of the scope of patent application. Made. A surface protection film is a surface protection film formed by forming an adhesive layer on one side of a resin film. The adhesive layer is the adhesive composition according to any one of claims 1 to 6 of the scope of patent application. Cross-linked. The surface protection film according to item 8 of the scope of patent application, which is used as a surface protection film of a polarizing plate. The surface protection film according to item 8 of the scope of patent application, which is used as a surface protection film for precision electrical / electronic parts, and the precision electrical / electronic parts are selected from the group consisting of flexible printed circuit boards and rigid printed circuits. Either a precision electrical / electronic component set consisting of a circuit board and a transparent conductive film.