TW201710434A - Surface-protective film for polarizing plate - Google Patents

Abstract

The present invention provides a surface-protective film for polarizing plate. The surface-protective film has excellent adhesion force balance under low peel speed and high peel speed, and has excellent attaching force to polarizing plate even in low adhesion force. Therefore, the surface-protective film has excellent durability, re-operability and antistatic ability. A surface-protective film for polarizing plate composed by forming an adhesion agent layer in a surface of a resin film, wherein the adhesion agent layer is composed by crosslinking adhesion agent composition having an acrylic polymer, a crosslinking agent and an antistatic agent, characterized in that: the acrylic polymer is composed by a copolymer which is copolymerized by (A) a (meth)acrylate Monomer having an alkyl group with 4 to 18 carbon atoms, (B) a copolymerizable monomer having hydroxyl group and (C) a copolymerizable monomer having carboxyl group. In the shear holing power test for polarizing plate under loading 500g and leaving 24 hours at 23 DEG C, the surface-protective film for polarizing plate attached in the polarizing plate does not have dislocation.

Description

Surface protection film for polarizing plate

The present invention relates to a surface protective film for a polarizing plate. More specifically, the surface protective film for a polarizing plate is excellent in the balance of adhesion at a low-speed peeling speed and a high-speed peeling speed, and has excellent adhesion to a polarizing plate even when the adhesive force is small, durability, and reworkability. And antistatic properties are also excellent.

Conventionally, in the manufacturing step of an optical member such as a polarizing plate or a phase difference plate which is a member constituting a liquid crystal display, a surface protective film for temporarily protecting the surface of the optical member is attached. Such a surface protective film is used only in the step of manufacturing an optical component, and when the optical component is mounted on a liquid crystal display, it is peeled off from the optical component. Such a surface protective film for protecting the surface of the optical member is also generally referred to as a step film since it is used only in the manufacturing step.

The surface protective film used in the step of manufacturing the optical member is formed with an adhesive layer on one side of an optically transparent polyethylene terephthalate (PET) resin film, but is bonded to the optical Before the component, a release-treated release film for protecting the adhesive layer is attached to the adhesive layer.

In addition, the optical member such as the polarizing plate or the retardation film is inspected with the surface protective film, and the product is inspected for optical evaluation such as the display capability, hue, contrast, and foreign matter incorporation of the liquid crystal display panel. Performance needs In view of this, it is required that there is no adhesion of air bubbles or foreign matter in the adhesive layer.

In addition, in recent years, when the surface protective film is peeled off from an optical member such as a polarizing plate or a phase difference plate, the peeling static electricity generated by the static electricity generated when the adhesive layer is peeled off from the adherend may cause electrical control of the liquid crystal display. The failure of the circuit requires excellent antistatic properties for the adhesive layer.

In addition, when the surface protective film is bonded to an optical member such as a polarizing plate or a retardation film, the surface protective film may be temporarily peeled off for various reasons, and then the surface protective film may be newly bonded again. Therefore, in this case, it is required. It is easy to peel off from the optical component of the adherend (re-operability).

Further, when the surface protective film is finally peeled off from an optical member such as a polarizing plate or a phase difference plate, it is required to be quickly peeled off. That is, it is required to be quickly peeled off even by high-speed peeling, and the adhesive force is small as the peeling speed changes.

As described above, in recent years, as a performance requirement for the adhesive layer constituting the surface protective film, from the viewpoint of ease of use when using the surface protective film, it is required to: (i) in the low-speed peeling speed and the high-speed peeling speed, A balance of adhesion; (ii) excellent antistatic properties; (iii) re-operability.

For example, in (i) the balance of the adhesive force is obtained in the low-speed peeling speed and the high-speed peeling speed, the following proposals are known.

An acrylic acid obtained by crosslinking a copolymer of a (meth)acrylic acid alkyl ester having an alkyl group having 7 or less carbon atoms and a carboxyl group-containing copolymerizable compound as a main component, which is crosslinked by a crosslinking agent In the adhesive layer of the type, there is a problem in that the adhesive is transferred to the adherend side or the adhesion to the adherend is greatly increased over time when the adhesive is adhered for a long period of time. In order to avoid these problems, it is known to arrange an adhesive layer using (meth) having an alkyl group having 8 to 10 carbon atoms. A copolymer of an alkyl acrylate and a copolymerizable compound having an alcoholic hydroxyl group, which is crosslinked by a crosslinking agent (Patent Document 1).

Further, it is also proposed to provide an adhesive layer in which a copolymer of an alkyl (meth)acrylate and a carboxyl group-containing copolymerizable compound is added in a small amount in the same copolymer as described above, which is crosslinked by a crosslinking agent. Treated adhesive layer. However, when the pressure-sensitive adhesive layer is used for surface protection of a plastic sheet having a low surface tension and a smooth surface, there is a problem that peeling occurs due to heating during processing or storage, or in the handicraft industry. The problem of poor removability at high speed peeling.

In order to solve these problems, an adhesive composition is proposed which is a) (meth)acrylic acid alkyl group having a (meth)acrylic acid alkyl ester having an alkyl group having 8 to 10 carbon atoms as a main component. a monomer mixture of b) a carboxyl group-containing copolymerizable compound in an amount of from 1 to 15 parts by weight, and c) a vinyl ester of an aliphatic carboxylic acid having from 3 to 5 parts by weight, based on 100 parts by weight of the ester. A crosslinking agent equal to or more than the carboxyl group of the above component b) is added to the copolymer (Patent Document 2).

In the adhesive composition described in Patent Document 2, the peeling phenomenon such as floating does not occur during processing or storage, and the adhesion strength is small in time, and the removability is excellent, and the long-term storage is particularly high in the environment. When the long-term storage is carried out, it is possible to carry out re-peeling with a small force. At this time, no residual glue is generated on the adherend, and re-peeling can be performed with a small force even when high-speed peeling is performed.

Further, (ii) excellent antistatic property, as a method for imparting antistatic properties to a surface protective film, a method of incorporating an antistatic agent into a base film or the like is disclosed. As the antistatic agent, for example, various cationic antistatics of (a) a 4-grade ammonium salt, a pyridinium salt, and a cationic group having a 1 to 3 amino group are disclosed. And (b) an anionic antistatic agent having an anionic group such as a sulfonate group, a sulfate group, a phosphate group or a phosphite group, and (c) an amphoteric antibody such as an amino acid or an aminosulfate (2) a nonionic antistatic agent such as an electrostatic agent, (d) an amino alcohol, a glycerin or a polyethylene glycol, or (e) a polymer antistatic agent which is obtained by polymerizing the above various antistatic agents. Patent Document 3).

Further, in recent years, it has been proposed to cause the base film to contain the antistatic agent or to apply the antistatic agent directly to the surface of the base film without directly coating the surface of the base film.

Further, (iii) re-operability, for example, an adhesive composition in which 0.0001 to 10 parts by weight of an isocyanate-based hardener and a specific hydrazine are added to 100 parts by weight of the acrylic resin in the acrylic resin is proposed. Acid salt oligomer (Patent Document 4).

In Patent Document 4, an alkyl acrylate having an alkyl group having about 2 to 12 carbon atoms or an alkyl methacrylate having an alkyl group having about 4 to 12 carbon atoms is used as a main monomer component, for example. Other functional group-containing monomer components such as a carboxyl group-containing monomer may be contained. It is preferable that the content of the main monomer is 50% by weight or more, or the content of the monomer component containing a functional group is 0.001 to 50% by weight, preferably 0.001 to 25% by weight, more preferably 0.01 to 25% by weight. In the adhesive composition of Patent Document 4, even under high temperature or high temperature and high humidity, the change in cohesive force and adhesive force with time is small, and the adhesion to the curved surface is also excellent, so that it has remanufacturability.

In general, when the adhesive layer is a soft property, residual glue is likely to occur, and the workability is liable to lower. That is, it is difficult to peel off at the time of erroneous bonding, and it is difficult to reattach easily. Therefore, in order to make it work again, it is considered that it is necessary to crosslink a monomer having a functional group such as a carboxyl group in a main component to impart a certain hardness to the adhesive layer.

Prior art literature Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. SHO 63-225677

Patent Document 2: Japanese Patent Laid-Open No. Hei 11-256111

Patent Document 3: Japanese Patent Laid-Open No. Hei 11-070629

Patent Document 4: Japanese Patent Laid-Open No. Hei 8-199130

In recent years, large screens of various displays such as liquid crystal displays have rapidly developed. However, with the large screen of the liquid crystal display, new problems have arisen in the steps of manufacturing the components of the liquid crystal display. For example, for a surface protective film for a polarizing plate for bonding to a surface of a polarizing plate to protect a polarizing plate, the following problem occurs.

In the prior art, in the manufacturing step of the polarizing plate which is a component of the liquid crystal display, after the surface protective film is bonded to the polarizing plate as the adherend, the peeling is required when the surface protective film is peeled off from the polarizing plate. This demand is satisfied by making the adhesion of the adhesive layer formed on the surface protective film small.

However, when the adhesion of the adhesive layer is small and the surface protective film is easily peeled off from the adherend, the adhesion of the surface protective film to the polarizing plate is lowered, so that the polarizing plate is accompanied by a large screen of the liquid crystal display. When the size is larger than in the related art, there is a problem in that the surface protective film is peeled off at the end portion of the polarizing plate.

The present invention has been made in view of the above circumstances, and the technical problem thereof is Provided is a surface protective film for a polarizing plate which has excellent adhesion balance at a low-speed peeling speed and a high-speed peeling speed, and has good adhesion to a polarizing plate even if the adhesive force is small, durability, reworkability, and antistatic property. Excellent performance.

In order to solve the technical problem, the present invention provides a surface protective film for a polarizing plate which is a surface protective film for a polarizing plate having an adhesive layer formed on one surface of a resin film, the adhesive layer comprising an acrylic polymer, The adhesive composition for a polarizing agent and an antistatic agent is crosslinked. The surface protective film for a polarizing plate is characterized in that the (A) alkyl group has a carbon number of C4 to C18 ( At least one or more of (B) a hydroxyl group-containing copolymerizable monomer, (C) at least one of carboxyl group-containing copolymerizable monomers, and (D) poly Asian At least one of a polyalkylene glycol mono(meth)acrylate monomer, (E) a hydroxyl group-free nitrogen-containing vinyl monomer or an alkoxy-containing alkyl (meth)acrylate a copolymer obtained by copolymerizing at least one of the monomers, wherein the crosslinking agent is a trifunctional isocyanate compound, and the adhesive composition further contains (F) a polyether modified oxygen having an HLB value of 7 to 12. The alkane compound is laminated on a polarizing plate subjected to AG treatment and cut into a width of 25 m. On the surface protective film for a polarizing plate having a size of 35 mm and a length of 35 mm, a load of 500 g was applied, and the film was allowed to stand in an environment of a temperature of 23 ° C for 24 hours, thereby preventing misalignment in the shear holding force test of the polarizing plate.

Further, the present invention provides a surface protective film for a polarizing plate which is a surface protective film for a polarizing plate having an adhesive layer formed on one surface of a resin film, the adhesive layer comprising an acrylic polymer, a crosslinking agent, The adhesive composition of the antistatic agent is crosslinked, and the surface protective film for a polarizing plate is characterized in that The acrylic polymer is composed of: (A) a total of 100 parts by weight of a (C) alkyl group having at least one of C4 to C18 (meth) acrylate monomers, and (B) a copolymerizable group containing a hydroxyl group. a total amount of at least one of 2 to 10 parts by weight of the body and (C) a total amount of at least one of the carboxyl group-containing copolymerizable monomers of 0.05 to 0.3 parts by weight, (D) a polyalkylene glycol mono ( A total of 3 to 40 parts by weight of at least one of the methyl acrylate monomers, (E) a nitrogen-containing vinyl monomer having no hydroxyl group or an alkyl (meth) acrylate monomer having an alkoxy group a copolymer obtained by copolymerizing at least one of a total of 0.1 to 20 parts by weight, wherein the crosslinking agent is a trifunctional isocyanate compound, and the number of carbon atoms of the (A) alkyl group is C4 to C18. The total amount of at least one of the (meth) acrylate monomers is 100 parts by weight, and the adhesive composition further contains (F) a polyether having a HLB value of 7 to 12 in a ratio of 0.001 to 0.5 parts by weight. At least one or more of the polar siloxane compounds are bonded to a polarizing plate subjected to AG treatment and cut into a surface of the polarizing plate having a size of 25 mm in width × 35 mm in length. Protection film, applying a load 500g, allowed to stand at a temperature of 23 ℃, for 24 hours, thereby shearing retention test of the polarizing plate in the dislocation-free.

The (D) polyalkylene glycol mono(meth)acrylate monomer is selected from the group consisting of polyalkylene glycol mono(meth)acrylates, methoxypolyalkylene glycol (meth)acrylic acid. At least one or more of the group consisting of esters and ethoxylated polyalkylene glycol (meth) acrylates, the average number of repeats of alkylene oxides constituting the polyalkylene glycol chain In the range of 3 to 14, the diester component in the monomer is 0.2% or less, the water content is 0.1% or less, and the solubility in water is preferably 2% or less in the state of 20% aqueous solution.

The above (B) hydroxyl group-containing copolymerizable monomer is selected from the group consisting of 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxy butyl (A) Acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (methyl) At least one or more of the group of compounds consisting of acrylamide is preferred.

The above (C) carboxyl group-containing copolymerizable monomer is selected from the group consisting of (meth)acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2-(meth) propylene decyloxy group. Ethyl hexahydrophthalic acid, 2-(methyl)propenyloxypropyl hexahydrophthalic acid, 2-(meth) propylene methoxyethyl phthalate, 2-(methyl ) acryloxyethyl succinic acid, 2-(methyl) propylene oxiranyl ethyl maleic acid, carboxy polycaprolactone mono (meth) acrylate, 2-(methyl) propylene methoxy ethoxylate At least one or more of the group of compounds consisting of tetrahydrophthalic acid is preferred.

The trifunctional isocyanate compound is an isocyanurate selected from the group consisting of a hexamethylene diisocyanate compound, an isocyanurate body of an isophorone diisocyanate compound, and an adduct of a hexamethylene diisocyanate compound. An adduct of an isophorone diisocyanate compound, a biuret of a hexamethylene diisocyanate compound, a biuret of an isophorone diisocyanate compound, an isocyanurate body of a toluene diisocyanate compound An isocyanurate body of a benzene dimethylene diisocyanate compound, an isocyanurate body of a hydrogenated benzene dimethylene diisocyanate compound, an adduct of a tolylene diisocyanate compound, benzene dimethylene diisocyanate At least one or more of the compound groups of the compound adduct and the hydrogenated benzene dimethylene diisocyanate compound adduct are preferred.

100 parts by weight based on 100 parts by weight of the (A) alkyl group having at least one of C4 to C18 (meth) acrylate monomers, and 0.01 to 5.0 parts by weight in the adhesive composition. The above (J) antistatic agent preferably has an ionic compound having a melting point of 25 to 50 ° C and a solid at 25 ° C.

In the polarizing plate, the adhesive layer has an adhesive force at a low-speed peeling speed of 0.3 m/min of 0.04 to 0.2 N/25 mm, and an adhesive force at a high-speed peeling speed of 30 m/min is preferably 2.0 N/25 mm or less.

The surface resistivity of the pressure-sensitive adhesive layer is 9.0 × 10 ^{+ 11} Ω / □ or less, and the peeling static voltage is preferably ± 0 to 0.5 kV.

It is preferable to perform an antistatic treatment and an antifouling treatment on the opposite side of the resin film on the side where the adhesive layer is formed.

According to the present invention, it is possible to provide a surface protective film for a polarizing plate which is excellent in balance of adhesion at a low-speed peeling speed and a high-speed peeling speed, and has excellent adhesion to a polarizing plate even if the adhesive force is small, durability, and re-operation Excellent in properties and antistatic properties.

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

The surface protective film for a polarizing plate of the present invention is a surface protective film for a polarizing plate in which an adhesive layer is formed on one surface of a resin film, and the adhesive layer is adhered by an acrylic polymer, a crosslinking agent, and an antistatic agent. The surface protective film for a polarizing plate is characterized in that the acrylic polymer is composed of (A) an alkyl group having a C4 to C18 carbon number in a (meth) acrylate monomer. At least one or more of (B) at least one of hydroxyl group-containing copolymerizable monomers, (C) at least one of carboxyl group-containing copolymerizable monomers, and (D) polyalkylene glycol mono(methyl) At least one or more of acrylate monomers, (E) nitrogen-containing ethylene having no hydroxyl group a copolymer obtained by copolymerizing at least one of a base monomer or an alkoxy-containing alkyl (meth) acrylate monomer, the crosslinking agent being a trifunctional isocyanate compound, and the adhesive composition further A polyether-modified siloxane compound having a (F) HLB value of 7 to 12 is applied to a polarizing plate subjected to AG treatment and applied to a surface protective film for a polarizing plate having a width of 25 mm and a length of 35 mm. The load was 500 g, and it was allowed to stand in an environment of a temperature of 25 ° C for 24 hours, and thus the shear holding force test for the polarizing plate was carried out without misalignment.

Further, the surface protective film for a polarizing plate of the present invention is a surface protective film for a polarizing plate in which an adhesive layer is formed on one surface of a resin film, and the adhesive layer contains an acrylic polymer, a crosslinking agent, and an antistatic agent. The adhesive composition for cross-linking is characterized in that the acrylic polymer is composed of: (A) a (meth) acrylate monomer having an alkyl group having a C4 to C18 carbon number At least one of a total amount of at least one of 100 parts by weight of (B) at least one of hydroxyl group-containing copolymerizable monomers, 2 to 10 parts by weight, and (C) a carboxyl group-containing copolymerizable monomer. The total amount of the above is 0.05 to 0.3 parts by weight, and the total amount of at least one or more of (D) polyalkylene glycol mono(meth)acrylate monomers is 3 to 40 parts by weight, and (E) contains no hydroxyl group. a copolymer of a total of 0.1 to 20 parts by weight of at least one of a nitrogen-vinyl monomer or an alkoxy-containing alkyl (meth) acrylate monomer, which is a trifunctional group An isocyanate compound to the (meth) acrylate monomer having a C4 to C18 carbon number relative to the (A) alkyl group The adhesive composition further contains at least one of (A) a polyether-modified siloxane compound having an HLB value of 7 to 12 in a total amount of 0.001 to 0.5 parts by weight in a total amount of 0.001 to 0.5 parts by weight. Surface protection of the polarizing plate cut into a width of 25 mm × a length of 35 mm on a polarizing plate subjected to AG treatment On the film, a load of 500 g was applied, and it was allowed to stand in an environment of a temperature of 23 ° C for 24 hours, and the shear holding force test for the polarizing plate was carried out without misalignment.

Examples of the (meth) acrylate monomer having a CA to C18 carbon atom as the (A) alkyl group include butyl (meth)acrylate, isobutyl (meth)acrylate, and pentane (meth)acrylate. Ester, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (methyl) ) decyl acrylate, isodecyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate , tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, cetyl (meth)acrylate, heptadecyl (meth)acrylate , octadecyl (meth) acrylate, myristyl (meth) acrylate, isomyristyl (meth) acrylate, cetyl (meth) acrylate, isocetyl (meth) acrylate, ( Stearyl methacrylate, isostearyl (meth) acrylate, and the like.

Examples of the (B) hydroxyl group-containing copolymerizable monomer include 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. a hydroxyalkyl (meth) acrylate such as 2-hydroxyethyl (meth) acrylate, or N-hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N- A hydroxyl group-containing (meth) acrylamide such as hydroxyethyl (meth) acrylamide.

Selected from 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N At least one of a group consisting of hydroxy (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, and N-hydroxyethyl (meth) acrylamide It is better.

100 parts by weight based on 100 parts by weight of the (A) alkyl group having at least one of C4 to C18 (meth) acrylate monomers, and is contained in a total amount of 2 to 10 parts by weight (B) At least one or more of the hydroxyl group-containing copolymerizable monomers are preferably contained in an amount of 3.5 to 10 parts by weight, more preferably in an amount of 4.2 to 10 parts by weight.

(C) The carboxyl group-containing copolymerizable monomer is selected from the group consisting of (meth)acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2-(methyl) propylene methoxyethyl Hexahydrophthalic acid, 2-(methyl)propenyloxypropylhexahydrophthalic acid, 2-(methyl)propenyloxyethylphthalic acid, 2-(methyl)propene Methoxyethyl succinic acid, 2-(methyl) propylene oxiranyl ethyl maleic acid, carboxy polycaprolactone mono (meth) acrylate, 2-(methyl) propylene oxiranyl ethyl four At least one or more of the group of compounds consisting of hydrogen phthalic acid is preferred.

100 parts by weight of the total amount of at least one or more of the (meth) acrylate monomers having a CA to C18 carbon number of the (A) alkyl group is contained in a ratio of 0.05 to 0.3 parts by weight based on the total amount (C) At least one or more of the carboxyl group-containing copolymerizable monomers are preferred, and more preferably contained in an amount of 0.05 to 0.25 parts by weight, particularly preferably 0.05 to 0.2 parts by weight.

As the (D) polyalkylene glycol mono(meth)acrylate monomer, as long as it is a plurality of hydroxyl groups of the polyalkylene glycol, one hydroxyl group is esterified in the form of (meth) acrylate The compound can be. Since the (meth) acrylate group becomes a polymerizable group, it can be copolymerized with the main agent polymer. The other hydroxyl group may be OH itself, or may be an alkyl ether such as methyl ether or diethyl ether or a saturated carboxylic acid ester such as acetate.

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

(D) Polyalkylene Glycol Mono(meth)acrylate Monomer The average number of repeating alkyleneoxy groups of the polyalkylene glycol chain is preferably from 3 to 14. The "average number of repeats of the alkyleneoxy group" means a portion of the "polyalkylene glycol chain" contained in the molecular structure of the (D) polyalkylene glycol mono(meth)acrylate monomer. The average number of repeats of the alkyleneoxy units.

As the (D) polyalkylene glycol mono(meth)acrylate monomer, the diester component in the monomer is 0.2% or less, the water content is 0.1% or less, and the solubility with respect to water is 20%. The haze value in the aqueous solution state is preferably 2% or less.

The "diester component in the monomer" means the content of the polyalkylene glycol di(meth)acrylate contained in the (D) polyalkylene glycol mono(meth)acrylate monomer. (weight%).

The "water content" means the content (% by weight) of water contained in the (D) polyalkylene glycol mono(meth)acrylate monomer.

The "haze value in the state of the 20% aqueous solution" means the haze value (%) of the aqueous solution in the state of (D) the polyalkylene glycol mono(meth)acrylate monomer in an aqueous solution of 20% by weight. ). That is, the (D) polyalkylene glycol mono(meth)acrylate monomer must have not only water solubility (solubility with respect to water) of only 20% aqueous solution, but also The haze value (%) in the case of a 20% aqueous solution was low (less white turbidity).

Further, in the present specification, the haze value of the 20% aqueous solution is a value obtained by adding an aqueous solution to a quartz bath having an optical path length of 10 mm and measuring by a haze meter. This index is used as a degree of hydrophilicity of the (D) polyalkylene glycol mono(meth)acrylate monomer, and is used to select a solution having no white turbidity even at a high concentration, and a monomer having high hydrophilicity. And the imported indicators.

As (D) polyalkylene glycol mono (meth) acrylate monomer, selected from polyalkylene glycol mono (meth) acrylate, methoxy polyalkylene glycol (meth) acrylate At least one or more of the group of compounds composed of an ester and an ethoxylated polyalkylene glycol (meth) acrylate is preferred.

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, methoxy polybutylene Alcohol-(meth) acrylate, methoxy-polyethylene glycol-polypropylene glycol-(meth) acrylate, methoxy-polyethylene glycol-polybutylene glycol-(meth) acrylate, A Oxy-polypropylene glycol-polybutylene glycol-(meth)acrylate, methoxy-polyethylene glycol-polypropylene glycol-polybutylene glycol-(meth)acrylate; ethoxylated polyethylene glycol- (Meth) acrylate, ethoxypolypropylene glycol-(meth) acrylate, ethoxylated polybutylene glycol-(meth) acrylate, ethoxy-polyethylene glycol-polypropylene glycol-(methyl Acrylate, ethoxy-polyethylene glycol-polybutylene glycol-(meth)acrylic acid , Ethoxy - polyethylene glycol - polypropylene glycol - (meth) acrylate, ethoxy - polyethylene glycol - poly Propylene glycol-polybutylene glycol-(meth)acrylate and the like.

100 parts by weight based on the total amount of at least one of the (A) alkyl group having a C4 to C18 (meth) acrylate monomer, and containing (D) in a total amount of 3 to 40 parts by weight. At least one of the polyalkylene glycol mono(meth)acrylate monomers is preferred, and it is preferably contained in an amount of from 3 to 30 parts by weight, particularly preferably from 5 to 30 parts by weight.

The acrylic polymer may further contain at least one of (E) a hydroxyl group-free nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth) acrylate monomer. In (E), examples of the (E-1) nitrogen-containing vinyl monomer include a vinyl halide-containing vinyl monomer, an amino group-containing vinyl monomer, and a nitrogen-containing heterocyclic structure. Base monomer and the like. More specifically, N-vinyl-2-pyrrolidone, N-vinylpyrrolidone, methylvinylpyrrolidone, N-vinylpyridine, N-vinylacridone, N-vinylpyrimidine, N -vinylpyridazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N- a cyclic nitrogen-vinyl compound having an N-vinyl substituted heterocyclic structure such as vinyl laurylamine; N-(meth)acryloylmorpholine, N-(methyl)propenylpyridazine, N-(methyl)propenyl aziridine, N-(methyl)propenyl azetidine, N-(methyl)propenylpyrrolidine, N-(methyl)acrylonitrile Ring having a heterocyclic structure substituted with N-(meth)acrylinyl group, such as pyridine, N-(methyl)propenylfluorenyl azepine or N-(methyl)propenyl azepine Nitro-vinyl compound; N-cyclohexylmaleimide, N-phenylmaleimide, etc. cyclic nitrogen-vinyl group containing a heterocyclic structure having a nitrogen atom and an ethylenically unsaturated bond in the ring. Compound; (meth) acrylamide, N-methyl (methyl) Alkenyl acyl amine, N- isopropyl (meth) acrylamide, N- t-butyl (meth) An unsubstituted or monoalkyl-substituted (meth) acrylamide such as acrylamide; N,N-dimethyl(meth) acrylamide, N,N-diethyl(meth) acrylamide, N,N-dipropyl acrylamide, N,N-diisopropyl(meth) acrylamide, N,N-dibutyl(meth) acrylamide, N-ethyl-N- Dialkyl substitutions such as (meth) acrylamide, N-methyl-N-propyl (meth) acrylamide, N-methyl-N-isopropyl (meth) acrylamide (A) Acrylamide; 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-diethylamino Methyl (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 Dioxane such as t-butylaminoethyl (meth) acrylate Amino (meth) acrylate; N,N-dimethylaminopropyl (meth) acrylamide, N,N-diethylaminopropyl (meth) acrylamide, N, N-di Propylaminopropyl (meth) acrylamide, N,N-diisopropylaminopropyl (meth) acrylamide, N-ethyl-N-methylaminopropyl (meth) propylene oxime N,N-dialkyl such as amine, N-methyl-N-propylaminopropyl (meth) acrylamide, N-methyl-N-isopropylaminopropyl (meth) acrylamide Substituted aminopropyl (meth) acrylamide; N-vinyl carbamide, N-vinyl acetamide, N-vinyl acetamide, N-vinyl-N-methyl acetamide, etc. N-methoxymethyl (meth) acrylamide, N-ethoxyethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone propylene oxime A (meth) acrylamide such as an amine or N,N-methylenebis(meth)acrylamide or an unsaturated carboxylic acid nitrile such as (meth)acrylonitrile.

The (E-1) nitrogen-containing vinyl monomer preferably contains no hydroxyl group, and preferably contains no hydroxyl group or carboxyl group. As such a monomer, the above-exemplified monomers, for example, an acrylic monomer containing an N,N-dialkyl substituted amino group or an N,N-dialkyl substituted decylamino group; N-vinyl-2- N-vinyl substituted indolamines such as pyrrolidone, N-vinyl caprolactam, N-vinyl-2-piperidone, etc.; N-(methyl)propenylmorpholine or N-(methyl) N-(meth)acryloyl-substituted cyclic amines such as acrylamidopyrrolidine are preferred.

In (E), examples of the (E-2) alkoxy group-containing alkyl (meth) acrylate monomer include 2-methoxyethyl (meth) acrylate and 2-ethoxy group. Ethyl (meth) acrylate, 2-propoxyethyl (meth) acrylate, 2-isopropoxyethyl (meth) acrylate, 2-butoxyethyl (meth) acrylate Ester, 2-methoxypropyl (meth) acrylate, 2-ethoxy propyl (meth) acrylate, 2-propoxy propyl (meth) acrylate, 2-isopropoxy Propyl (meth) acrylate, 2-butoxypropyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-ethoxy propyl (meth) acrylate , 3-propoxypropyl (meth) acrylate, 3-isopropoxy propyl (meth) acrylate, 3-butoxypropyl (meth) acrylate, 4-methoxy butyl (meth) acrylate, 4-ethoxybutyl (meth) acrylate, 4-propoxy butyl (meth) acrylate, 4-isopropoxy butyl (meth) acrylate , 4-butoxybutyl (meth) acrylate, and the like.

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

(E) a nitrogen-containing vinyl monomer having no hydroxyl group or 100 parts by weight based on the total amount of at least one of the (A) alkyl group having a C4 to C18 (meth) acrylate monomer; Alkoxy-containing alkyl (meth) acrylate monomer At least one of the above is preferably contained in a proportion of 0.1 to 20 parts by weight in total, more preferably 0.3 to 10 parts by weight, and particularly preferably 0.3 to 8 parts by weight. One type or two or more types of (E-1) a hydroxyl group-free nitrogen-containing vinyl monomer and (E-2) alkoxy group-containing alkyl (meth) acrylate monomer may be used.

The adhesive composition of the present invention may contain (F) a polyether modified siloxane compound having an HLB value of 7 to 12. The polyether-modified siloxane compound is a siloxane compound having a polyether group, and includes a polyoxyl group-containing siloxane unit in addition to the usual siloxane 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 groups or aryl groups, R ² and R ³ represent one or two or more alkylene groups, and R ⁴ represents one or two or more alkyl groups or fluorenyl groups ( End group). The polyether group may, for example, be a polyoxyalkylene group such as polyoxyethylene [(C ₂ H ₄ O) _n ] or polyoxypropylene [(C ₃ H ₆ O) _n ].

100 parts by weight of the total amount of at least one or more of the (meth) acrylate monomers having a CA to C18 (A) alkyl group is contained in a ratio of 0.001 to 0.5 parts by weight in total (F) At least one or more of the polyether-modified siloxane oxide compounds having an HLB value of 7 to 12 are more preferably 0.01 to 0.5 parts by weight. The HLB value is, for example, a hydrophilic-lipophilic balance (hydrophilic-lipophilic ratio) prescribed in JIS K3211 (the term of surfactant).

The polyether-modified siloxane compound can be obtained, for example, by grafting an organic compound having an unsaturated bond and a polyoxyalkylene group to a polyorganosiloxane main chain having a hydrogenated fluorenyl group by a hydrogenation reaction. Specifically, a dimethyl methoxy oxane-methyl (polyoxyethylene) fluorene copolymer, dimethyl methoxy oxane-methyl (polyoxyethylene) decane-A (polyoxypropylene) alkane copolymer, two A methyl methoxy alkane-methyl (polyoxypropylene) siloxane polymer or the like. The HLB value of the polyether modified siloxane compound can be adjusted by selecting the ratio of the polyether group to the decyloxy group. By adding (F) a polyether modified siloxane compound having an HLB value of 7 to 12 to the adhesive composition, the adhesion and reworkability of the adhesive can be improved.

The trifunctional isocyanate compound may be at least one selected from the group consisting of polyisocyanate compounds having three isocyanate (NCO) groups in one molecule, or two or more kinds thereof. The polyisocyanate compound may be classified into an aliphatic isocyanate, an aromatic isocyanate, an acyclic isocyanate, or an alicyclic isocyanate.

Examples of the trifunctional isocyanate compound include a biuret modified product or an isocyanurate modified product of a bifunctional isocyanate compound (a compound having two NCO groups in one molecule), and trimethylolpropane ( An adduct (polyol modified product) of a trihydric or higher polyvalent alcohol (a compound having at least three or more OH groups in one molecule) such as TMP) or glycerin.

As a trifunctional isocyanate compound, an isocyanurate body selected from a hexamethylene diisocyanate compound, an isocyanurate body of an isophorone diisocyanate compound, and an adduct of a hexamethylene diisocyanate compound An adduct of an isophorone diisocyanate compound, a biuret of a hexamethylene diisocyanate compound, a biuret of an isophorone diisocyanate compound, an isocyanurate body of a toluene diisocyanate compound An isocyanurate body of a benzene dimethylene diisocyanate compound, an isocyanurate body of a hydrogenated benzene dimethylene diisocyanate compound, an adduct of a tolylene diisocyanate compound, benzene dimethylene diisocyanate Adduct of compound, hydrogenated dimethylene diisocyanate compound At least one or more of the compound groups composed of the adducts are preferred.

100 parts by weight based on 100 parts by weight of the (A) alkyl group having at least one of C4 to C18 (meth) acrylate monomers, and a trifunctional group in a total amount of 0.1 to 10 parts by weight. At least one or more of the isocyanate compounds are preferred, and more preferably contained in an amount of 0.1 to 6 parts by weight.

When a polyisocyanate compound is used as a crosslinking agent, the crosslinking catalyst may be a catalyst which acts as a catalyst for the reaction (crosslinking reaction) of the acrylic polymer and the crosslinking agent, and examples thereof include an amine such as a tertiary amine. Organometallic compounds such as a compound, a metal chelate compound, an organotin compound, an organic lead compound, and an organozinc compound.

Examples of the tertiary amine include a trialkylamine, N,N,N',N'-tetraalkyldiamine, N,N-dialkylamino alcohol, triethylenediamine, morpholine derivative, and piperazine. Pyrazine derivatives and the like.

The metal chelate compound is a compound in which one or more polydentate ligands L are bonded to the central metal atom M. The metal chelate compound 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 compound having a metal atom M of 1 is represented by M(L) _m (X) _n , m 1,n 0. When m is 2 or more, m of L may be the same ligand or different ligands. When n is 2 or more, n of 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 acetate, octyl acetate, oleyl acetate, lauryl acetate, and ethyl acetonitrile. A β-ketoester such as stearyl ester or a β-diketone such as acetamidine (alias 2,4-pentanedione), 2,4-hexanedione or benzamidine. These are keto-enol tautomer compounds, and in the polydentate ligand L, they may also be enolates (for example, acetoacetate) in which the enol is deprotonated.

Examples of the monodentate ligand X include a halogen atom such as a chlorine atom or a bromine atom, a pentamidine group, a hexyl group, a 2-ethylhexyl group, a octyl group, a fluorenyl group, a fluorenyl group, and a fluorenyl group. An alkoxy group such as an oxenyl group, an methoxy group, a methoxy group, an ethoxy group, a n-propoxy group, an isopropoxy group or a butoxy group.

Specific examples of the metal chelate compound include tris(2,4-pentanedione)iron (III), triethylsulfonium iron, triacetin, titanium triacetone, triacetonitrile, and acetone. Zinc, triethylammonium acetone, tetraethylguanidinium zirconium, tris(2,4-hexanedione)iron (III), bis(2,4-hexanedione)zinc, tris(2,4-hexyl) Diketo) titanium, tris(2,4-hexanedione) aluminum, tetrakis(2,4-hexanedione)zirconium, and the like.

The organotin compound may, for example, be a dialkyltin oxide or a fatty acid salt of a dialkyltin or a fatty acid salt of a divalent tin.

The crosslinking catalyst is preferably a metal chelate compound or an organotin compound. As the metal chelate compound, an aluminum chelate compound, a titanium chelate compound, an iron chelate compound, a tin chelate compound or the like is preferred. As the organotin compound, at least one or more selected from the group consisting of dioctyltin oxide and dioctyltin dilaurate is preferred.

a cross-linking catalyst is contained in a total amount of 0.001 to 0.5 parts by weight based on 100 parts by weight of the total of at least one of the (C)-C18 (C)-C18 (meth) acrylate monomers having a carbon number of (A) alkyl group. At least one of the above is preferred.

As a keto-enol tautomer compound, ethyl acetonitrile Methyl ester, ethyl acetate, octyl acetate, oleyl acetate, lauryl acetate, stearyl acetate, etc., or acetamidine, 2,4- A β-diketone such as adipone or benzamidine. Ketone-enol tautomer compound In an adhesive composition using a polyisocyanate compound as a crosslinking agent, by blocking an isocyanate group of a crosslinking agent, adhesion of a binder after addition of a crosslinking agent can be suppressed Excessive viscosity rises or gels, prolonging the pot life of the adhesive composition.

As the keto-enol tautomer compound, at least one or more selected from the group consisting of ethyl acetonide and ethyl acetate ethyl acetate is particularly preferred.

The ketone-ene is contained in a total amount of 0.1 to 300 parts by weight based on 100 parts by weight of the total of at least one of the (C)-C18 (C)-C18 (meth) acrylate monomers having a carbon number of (A) alkyl group. At least one or more of the alcohol tautomeric compounds are preferred, and a ratio of 1.0 to 30.0 parts by weight is more preferable.

In contrast to the crosslinking catalyst, the keto-enol tautomer compound has an effect of inhibiting crosslinking, and therefore it is preferred to appropriately set the ratio of the keto-enol tautomer compound to the crosslinking catalyst. In order to prolong the pot life of the adhesive composition and improve storage stability, the weight ratio of the crosslinking catalyst to the keto-enol tautomer compound (keto-enol tautomer compound/crosslinking catalyst) is 70~ 1000 is better.

(J) The antistatic agent has a melting point of 25 to 50 ° C, and is preferably a solid ionic compound at 25 ° C.

In the present invention, an ionic compound having a melting point of 25 to 50 ° C and a solid at 25 ° C is added as an antistatic agent (J) to the adhesive composition. These (J) antistatic agents have a low melting point and a long-chain alkyl group, so it is presumed that they are aggregated with acrylic acid. The affinity of the compound is high.

Examples of the (J) antistatic agent include an ionic compound having a melting point of 25 to 50 ° C and a solid at 25 ° C in the adhesive composition.

An ionic compound having a melting point of 25 to 50 ° C and a solid at 25 ° C, which is an ionic compound having a cation and an anion, and examples thereof include a pyridine cation, an imidazolium cation, a pyrimidine cation, and a pyrazolium cation. a nitrogen-containing phosphonium cation or a phosphonium cation or a phosphonium cation such as a cation, a pyrrolidinium cation or an ammonium cation, and the anion is a hexafluorophosphate (PF ₆ ^- ), a thiocyanate (SCN ^- ), an alkylbenzene sulfonate. (RC ₆ H ₄ SO ₃ ^- ), perchlorate (ClO ₄ ^- ), tetrafluoroborate (BF ₄ ^- ), bis(fluorosulfonyl) sulfinium imide (FSI), double (three A compound of an inorganic or organic anion such as fluoromethanesulfonyl)imide salt (TFSI) or trifluoromethanesulfonate (TF). A solid at a normal temperature (for example, 25 ° C) is preferred, and a compound having a melting point of 25 to 50 ° C can be obtained by selecting the chain length of the alkyl group or the position and number of the substituent. The cation is preferably a 4-stage nitrogen sulfonium cation, and examples thereof include a 1-alkylpyridinium group (a carbon atom at the 2nd to 6th position may have a substituent or may be unsubstituted), and a 4-stage pyridinium cation or the like. 3-Dialkylimidazolium (a carbon atom at the 2, 4, and 5 positions may have a substituent or may be unsubstituted.) A 4-stage imidazolium cation, a tetra-ammonium cation such as a tetraalkylammonium or the like.

100 parts by weight based on 100 parts by weight of the (A) alkyl group having at least one of C4 to C18 (meth) acrylate monomers, and a melting point of 25 in a total amount of 0.01 to 5.0 parts by weight. At least one or more of the ionic compounds which are solid at 50 ° C and which are solid at 25 ° C are preferred.

Specific examples of the (J) antistatic agent are not particularly limited, and specific examples of the ionic compound having a melting point of 25 to 50 ° C and being solid at 25 ° C For example, 1-octylpyridinium hexafluorophosphate, 1-mercaptopyridinium hexafluorophosphate, 2-methyl-1-dodecylpyridinium hexafluoride phosphate, 1 -octylpyridinium dodecylbenzenesulfonate, 1-dodecylpyridinium thiocyanate, 1-dodecylpyridinium dodecylbenzenesulfonate, 4-methyl-1 - octylpyridinium hexafluorophosphate or the like.

Further, as other components, a copolymerizable (meth)acrylic monomer having an alkyleneoxy group, a (meth)acrylamide monomer, a dialkyl-substituted acrylamide monomer, and a surface active agent may be appropriately added. Conventional additives such as a curing agent, a curing accelerator, a plasticizer, a filler, a curing retarder, a processing aid, an anti-aging agent, and an antioxidant. The materials may be used singly or in combination of two or more.

The acrylic polymer used in the adhesive composition of the present invention is composed of (A) at least one of (C) a C1-C18 (meth) acrylate monomer having an alkyl group, and (B) a hydroxyl group-containing one. At least one or more of the copolymerizable monomers and at least one of the (C) carboxyl group-containing copolymerizable monomers are copolymerized by copolymerization. Further, the acrylic polymer may be at least one of (A) at least one of a C4 to C18 (meth) acrylate monomer having a C4 to C18 alkyl group, and at least (B) a hydroxyl group-containing copolymerizable monomer. At least one of (C) a carboxyl group-containing copolymerizable monomer, at least one of (D) a polyalkylene glycol mono(meth)acrylate monomer, and (E) a hydroxyl group-free content A copolymer obtained by copolymerizing at least one of a nitrogen-vinyl monomer or an alkoxy-containing alkyl (meth) acrylate monomer. The polymerization method of the acrylic polymer is not particularly limited, and an appropriate polymerization method such as solution polymerization or emulsion polymerization can be used.

The adhesive composition of the present invention can further be obtained by adding (F) a polyether modified siloxane compound having an HLB value of 7 to 12 to the above acrylic polymer. The trifunctional isocyanate compound of the crosslinking agent, an ionic compound having a melting point of 25 to 50 ° C and being solid at 25 ° C as an antistatic agent, and an appropriate optional additive are prepared.

In the preparation of the acrylic polymer, in order to reduce the incorporation of moisture into the adhesive composition, it is preferred to carry out a polymerization reaction under anhydrous conditions, such as solution polymerization using an anhydrous organic solvent. In particular, the (D) polyalkylene glycol mono(meth)acrylate monomer has high hydrophilicity, and therefore it is preferred to use a water content lower.

In order to avoid an increase in the viscosity of the adhesive composition, each monomer used for the preparation of the acrylic polymer for the main component minimizes the amount of the polyfunctional (difunctional or higher) monomer which can function as a crosslinking agent. good. In particular, the diester component corresponding to the (D) polyalkylene glycol mono(meth)acrylate monomer is a difunctional (meth) acrylate. Therefore, it is preferred to use a small diester component. .

The acrylic polymer contains (meth) acrylate monomer, (meth)acrylic acid, (meth) acrylamide, etc. in a ratio of 50 to 100 parts by weight based on 100 parts by weight of the acrylic polymer. Acrylic monomers are preferred.

Further, the acid value of the acrylic polymer is preferably from 0.01 to 8.0. Thereby, the contamination property can be improved, and the performance of preventing the occurrence of residual glue can be improved.

Here, the "acid value" is an index indicating the content of the acid, and indicates the number of mg of potassium hydroxide required to neutralize 1 g of the carboxyl group-containing polymer.

The adhesion of the adhesive layer obtained by crosslinking the adhesive composition to the polarizing plate is 0.04 to 0.2 N/25 mm at a low speed peeling speed of 0.3 m/min, and the adhesion at a high speed peeling speed of 30 m/min. It is preferably 2.0N/25mm or less. As a result, it is possible to obtain a performance in which the change in the adhesive force due to the peeling speed is small, and it is possible to quickly peel off even at the time of high-speed peeling. In addition, due to Since it is re-bonded, even when the surface protection film is temporarily peeled off, excessive force is not required, and it is easily peeled off from the adherend.

The surface resistivity of the adhesive layer obtained by crosslinking the adhesive composition is preferably 9.0 × 10 ^{+ 11} Ω / □ or less, and the peeling static voltage is preferably ± 0 to 0.5 kV. Further, in the present invention, "±0 to 0.5 kV" means 0 to -0.5 kV and 0 to +0.5 kV, which means -0.5 to +0.5 kV. When the surface resistivity is large, the performance of dissipating static electricity due to charging at the time of peeling is poor. Therefore, by making the surface resistivity sufficiently small, the peeling static voltage due to the static electricity generated when the adhesive layer is peeled off from the adherend is lowered, and it is possible to suppress the influence on the electric control circuit of the adherend.

The adhesive layer formed by crosslinking the adhesive composition preferably has a gel fraction of 95 to 100%, and the adhesion at the low-speed peeling speed is not excessively lowered by the high gel fraction. The elution of the unpolymerized monomer or oligomer derived from the acrylic polymer can improve reworkability, durability under high temperature and high humidity, and suppress contamination of the adherend.

An adhesive film can be obtained by forming an adhesive layer obtained by crosslinking the adhesive composition on one side or both sides of a resin film. Further, the surface protective film for a polarizing plate of the present invention is a surface protective film in which an adhesive layer obtained by crosslinking the adhesive composition is formed on one surface of a resin film. When the surface protective film for a polarizing plate of the present invention is bonded to a polarizing plate, it has no misalignment in the shear holding force test, and although the adhesion is small, the adhesion to the polarizing plate is good, durability, reworkability, and antistatic property. Excellent performance. Therefore, it can be applied to the use of the surface protective film of a polarizing plate. Examples of the polarizing plate include glare, plane (universal), and anti-glare (AG). Examples of the protective film material on the surface of the polarizing plate include a TAC-based film (triacetyl cellulose-based compound), an acrylic film, and the like.

The test conditions of the shear retention force include, for example, a load (mass of a heavy object) of 500 g, an ambient temperature of 23 ° C, and a standing time of 24 hours. This test condition is suitable as a judgment pointer for a good adhesion to the surface protective film of a polarizing plate. The contact area (size) of the surface protective film for polarizing plates of the polarizing plate of the adherend with respect to the shear holding force test is 25 mm × 35 mm. The details of the test method (device, etc.) can be based on, for example, a holding force test of JIS Z 0237 (adhesive tape, adhesive sheet test method).

A resin film such as a polyester film or the like can be used as the resin film serving as the base material of the adhesive layer or the release film (separator) for protecting the adhesive surface.

The resin film as the substrate can be subjected to antifouling treatment by an antimony agent such as an anthrone or a fluorine release agent, a coating agent, or cerium oxide microparticles on the opposite side of the adhesive layer on which the resin film is formed. The antistatic treatment is carried out by coating or blending an antistatic agent or the like.

The release film is subjected to a release treatment by an anthrone or a fluorine-based release agent on the surface of the release film that adheres to the adhesive surface of the adhesive layer.

Example

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

<Manufacture of acrylic polymer>

[Example 1]

Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, and the air in the reaction apparatus was replaced with nitrogen. Then, 100 parts by weight of 2-ethylhexyl acrylate, 8.0 parts by weight of 8-hydroxyoctyl acrylate, 0.1 parts by weight of acrylic acid, and polypropylene glycol monoacrylate (constituting a polyalkylene glycol chain) were added to the reaction apparatus. The average number of repeats of alkoxy groups is n=12, two of the monomers The ester component was 0.1%, the solubility in water was a haze value of 0.8% in a 20% aqueous solution state, a water content of 0.05%), 8 parts by weight, and 1 part by weight of N-vinylpyrrolidone, and a solvent (acetic acid) was added thereto. Ethyl ester) 60 parts by weight. Then, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise thereto over 2 hours, and the mixture was reacted at 65 ° C for 6 hours to obtain an acrylic polymer solution of Example 1 having a weight average molecular weight of 500,000. A part of the acrylic polymer was extracted and used as a measurement sample of an acid value described later.

[Examples 2 to 8 and Comparative Examples 1 to 4]

In the same manner as the acrylic polymer solution used in the above Example 1, except that the composition of the monomer was set to the composition of (A) to (E) of Table 1, respectively, it was obtained for Examples 2 to 8. And the acrylic polymer solutions of Comparative Examples 1 to 4.

<Manufacture of Adhesive Composition and Surface Protective Film>

[Example 1]

To the acrylic polymer solution of the above-prepared Example 1, a polyether modified siloxane compound (HLB value: 7) 0.05 parts by weight, and 1-octylpyridinium hexafluorophosphate 1.0 parts by weight, B. 8.5 parts by weight of hydrazine acetone, and after stirring, 4.0 parts by weight of CORONATE HX (isocyanurate body of hexamethylene diisocyanate compound) and 0.1 part by weight of titanium triacetone acetonate were added and stirred to obtain the adhesion of Example 1. Composition. The adhesive composition was applied onto a release film composed of an anthrone resin-coated polyethylene terephthalate (PET) film, and then the solvent was removed by drying at 90 ° C to obtain an adhesive layer. Adhesive sheet having a thickness of 25 μm.

Then, on the opposite side of the antistatic and antifouling surface of the antistatic and antifouling polyethylene terephthalate (PET) film on one side, The surface-protective film of Example 1 having a laminated structure of "PET film/adhesive layer/release film (PET film coated with an oxime resin) which has been subjected to antistatic and antifouling treatment) was obtained by transferring the adhesive sheet.

[Examples 2 to 8 and Comparative Examples 1 to 4]

Examples 2 to 8 and Comparative Examples 1 to 4 were obtained in the same manner as the surface protective film of Example 1 except that the composition of the additive was set to the composition of (F) to (J) of Table 2, respectively. Surface protection film.

In Tables 1 and 2, the addition ratio of each component is a numerical value of the weight component obtained by the total amount of the (A) group of 100 parts by weight, and is shown in parentheses.

Further, the compound names of the abbreviations of the respective components used in Tables 1 and 2 are shown in Tables 3 and 4. In addition, CORONATE (registered trademark) HX, CORONATE HL and CORONATE L are trade names of Japan Polyurethane Industrial Co., Ltd., Takenate (registered trademark) D-140N, D-127N, D-110N, D-120N are Mitsui Chemicals Co., Ltd. The company's trade name. For the group (D) of Table 3, the numerical value of "n" is the average number of repetitions of the alkyleneoxy group constituting the polyalkylene glycol chain. The value of "diester" is the diester component (%) in the monomer. The value of "moisture" is the moisture content (%). The value of "haze" is the haze value (%) in the state of 20% aqueous solution.

<Test method and evaluation>

The surface protective films of Examples 1 to 8 and Comparative Examples 1 to 4 were aged for 7 days in an environment of 23° C. and 50% RH, and then the release film (PET film coated with an anthrone resin) was peeled off. The film in which the adhesive layer was exposed was used as a measurement sample of the gel fraction and the surface resistivity.

Further, the surface protective film exposing the adhesive layer is bonded to the surface of the polarizing plate attached to the liquid crystal cell via the adhesive layer, and after being left for one day, 50 The autoclave treatment was carried out at ° C, 5 atm, and 20 minutes, and further allowed to stand at room temperature for 12 hours, and this was used as a measurement sample for adhesion, peeling static voltage, shear retention (dislocation), reworkability, and durability. The polarizing plate of the adherend is a polarizing plate which is subjected to AG treatment on the surface.

<gel fraction>

After the aging was completed, the mass of the adhesive layer separated from the measurement sample before bonding to the polarizing plate was accurately measured, and after immersing in toluene for 24 hours, it was filtered with a mesh of 200 mesh. Then, after the filtrate was dried at 100 ° C for 1 hour, the mass of the residue was accurately measured, and the gel fraction of the adhesive layer (adhesive layer after crosslinking) was calculated by the following formula.

Gel fraction (%) = insoluble portion mass (g) / mass of the adhesive layer (g) × 100

<adhesion>

Using the tensile tester, the measurement sample obtained above (bonding a 25 mm-wide surface protective film to the surface of the polarizing plate having the AG-treated surface) was applied at a low-speed peeling speed (0.3 m/min) in the 180° direction and The high-speed peeling speed (30 m/min) was peeled off, and the measured peeling strength was measured as the adhesive force (N/25 mm).

<surface resistivity>

After aging, the release film (PET film coated with an oxime resin) was peeled off before the polarizing plate was attached to expose the adhesive layer, and the adhesive layer was measured using a resistivity meter HIRESTA UP-HT450 (manufactured by Mitsubishi Chemical Analytech). Surface resistivity (Ω/□).

<peeling static voltage>

When the measurement sample obtained above was subjected to 180° peeling at a tensile speed of 30 m/min, a high-precision electrostatic sensor SK-035, SK-200 (Keyence shares have The polarizing plate to which the AG treatment was applied on the surface was measured for the voltage (static voltage) generated by charging, and the maximum value of the measured value was taken as the peeling static voltage (kV).

<Shear retention force for polarizing plate>

On a polarizing plate to which an AG treatment was applied, a surface protective film having a width of 25 mm × a length of 35 mm (the thickness of the adhesive layer was 20 μm) was attached and bonded to the surface of the polarizing plate at a temperature of 23 ° C. A load of 500 g was applied to the protective film, and the misalignment (mm) of the surface protective film after standing for 24 hours was measured.

<re-operability>

After drawing on the surface protective film of the measurement sample obtained above with a ballpoint pen (loading of 500 g, three times of back and forth), the surface protective film was peeled off from the polarizing plate, and the surface of the polarizing plate was observed, and it was confirmed that no contamination was transferred to the polarizing plate. The evaluation target standard was evaluated as "○" in the case where no contamination was transferred to the polarizing plate, and it was evaluated as "△" in the case where contamination was traced along at least a part of the ballpoint drawing trajectory, and contamination was confirmed along the trajectory drawn by the ballpoint pen. The transfer was confirmed to be "x" when the adhesive was detached from the surface of the adhesive.

<Durability>

The measurement sample obtained above was allowed to stand in an environment of 60 ° C and 90% RH for 250 hours, taken out at room temperature, and further left for 12 hours, and then the adhesion was measured to confirm that there was no significant increase compared with the initial adhesion. . The evaluation target standard was evaluated as "○" when the adhesion after the test was 1.5 times or less of the initial adhesion, and "x" when the adhesion was more than 1.5 times.

The evaluation results are shown in Table 5. Further, the surface resistivity is "mE + n" indicates embodiment "m × 10 ^{+ n"} (where, m is an arbitrary real values, n-is a positive integer).

Further, the misalignment described in Table 5 indicates the measured value of the misalignment (mm) of the surface protective film in the shear holding force test with respect to the polarizing plate.

The adhesion of the surface protective films of Examples 1 to 8 at a low-speed peeling speed of 0.3 m/min was 0.04 to 0.2 N/25 mm with respect to the polarizing plate of the adherend, and the adhesion at a high-speed peeling speed of 30 m/min was 2.0. N/25 mm or less, the surface resistivity is 9.0×10 ⁺¹¹ Ω/□ or less, the peeling static voltage is ±0 to 0.5 kV, and the load is 500 g, and the shear holding force test after leaving at 23 ° C for 24 hours has no misalignment. After the adhesive layer was drawn on the surface protective film with a ballpoint pen, there was no contamination transfer on the adherend, and the durability was excellent when placed in an environment of 60 ° C and 90% RH for 250 hours.

That is, all of the following performance requirements are met: (1) even if the adhesion is small, the bias is The adhesion of the diaphragm is also good; (2) durability, (3) re-operability, and (4) excellent antistatic performance.

The surface protective film of Comparative Example 1 may have no (D) polyalkylene glycol mono(meth)acrylate monomer, adhesive composition due to (C) carboxyl group-containing copolymerizable monomer. It does not contain (F) a polyether modified siloxane compound having an HLB value of 7 to 12, and (G) a trifunctional isocyanate compound is too small, and does not contain (J) an antistatic agent, so the low-speed peeling speed is 0.3 m/min. The adhesion at a high-speed peeling speed of 30 m/min is too large, the surface resistivity and the peeling static voltage are high, and there is a misalignment in the shear holding force test, and the workability and durability are poor.

The surface protective film of Comparative Example 2 may have too many diester components containing (c) a carboxyl group-containing (D) polyalkylene glycol mono(meth)acrylate monomer, and has a high water content. The solubility of water is low, and the HLB value of the (F) polyether modified siloxane compound is too large. Therefore, the adhesion at a low-speed peeling speed of 0.3 m/min and the high-speed peeling speed of 30 m/min is too large, and the surface resistivity and peeling static The voltage is high, there is a misalignment in the shear retention test, and the durability is poor.

In the surface protective film of Comparative Example 3, the acrylic polymer does not contain (B) a hydroxyl group-containing copolymerizable monomer, (C) a carboxyl group-containing copolymerizable monomer is excessive, and (D) a polyalkylene glycol mono (methyl group) The acrylate monomer has a large diester component, a high water content, and low solubility in water, so the gel fraction is low, and the adhesion at a low-speed peeling speed of 0.3 m/min and a high-speed peeling speed of 30 m/min is very large. Even if the surface resistivity is low, the peeling static voltage is high, and the workability is poor.

In the surface protective film of Comparative Example 4, the (HL) polyether modified siloxane compound had an excessively large HLB value and was misaligned in the shear retention test.

Thus, in the surface protective films of Comparative Examples 1 to 4, it is impossible to simultaneously It satisfies all of the following performance requirements: (1) good adhesion to a polarizing plate even if the adhesion is small; (2) durability, (3) re-operability, and (4) excellent antistatic property.

Real industry utilization

The surface protective film for a polarizing plate of the present invention solves the problem in the prior art that the polarization of the surface protective film is obtained by reducing the adhesion of the adhesive layer and allowing the surface protective film to be easily peeled off from the adherend. Since the adhesion of the sheet is lowered, the size of the polarizing plate is larger than that of the conventional one, and the problem of peeling off the protective film on the end surface of the polarizing plate is industrially. The value of utilization is large.

Claims (9)

A surface protective film for a polarizing plate is a surface protective film for a polarizing plate having an adhesive layer formed on one surface of a resin film, the adhesive layer comprising an adhesive containing an acrylic polymer, a crosslinking agent, and an antistatic agent. The surface protective film for a polarizing plate is characterized in that the acrylic polymer is composed of at least (A) a (meth) acrylate monomer having an alkyl group having a C4 to C18 carbon number; At least one or more of (B) a hydroxyl group-containing copolymerizable monomer, (C) at least one of carboxyl group-containing copolymerizable monomers, (D) polyalkylene glycol mono(meth)acrylic acid a copolymer obtained by copolymerizing at least one of at least one of ester monomers, (E) a hydroxyl group-free nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth) acrylate monomer In the composition, the crosslinking agent is a trifunctional isocyanate compound, and the adhesive composition further contains (F) a polyether modified siloxane compound having an HLB value of 7 to 12, and is bonded to a polarizing plate subjected to AG treatment. A surface protective film for the polarizing plate having a width of 25 mm × a length of 35 mm was applied, and a load of 500 g was applied. Left for 24 hours at a temperature of 23 ℃, thereby shearing retention force test, dislocation-free polarizing plates. A surface protective film for a polarizing plate is a surface protective film for a polarizing plate in which an adhesive layer is formed on one surface of a resin film, and the adhesive layer contains acrylic acid The adhesive composition of a polymer-like polymer, a crosslinking agent, and an antistatic agent is obtained by crosslinking a surface protective film of the polarizing plate, wherein the acrylic polymer has a carbon atom number of (A) alkyl group: C4 100 parts by weight of at least one of (C) a hydroxyl group-containing copolymerizable monomer, and a total amount of at least one or more of (B) a hydroxyl group-containing copolymerizable monomer, 2 to 10 parts by weight, (C) The total amount of at least one or more of at least one of the carboxyl group-containing copolymerizable monomers is 0.05 to 0.3 parts by weight, and the total amount of at least one of (D) polyalkylene glycol mono(meth)acrylate monomers is 3 to 40. And a total amount of at least one or more of (E) a hydroxyl group-containing nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth) acrylate monomer in an amount of 0.1 to 20 parts by weight, copolymerized The copolymer is a trifunctional isocyanate compound, and the total amount of at least one of the (A) alkyl groups having a C4 to C18 (meth) acrylate monomer is 100 or more. The adhesive composition further contains (F) a polyether modified oxirane compound having an HLB value of 7 to 12 in a total amount of 0.001 to 0.5 parts by weight in a total amount of 0.001 to 0.5 parts by weight. At least one of the above-mentioned polarizing plates subjected to the AG treatment is bonded to a surface protective film for a polarizing plate having a width of 25 mm and a length of 35 mm, and a load of 500 g is applied thereto, and the mixture is allowed to stand in an environment of a temperature of 23 ° C for 24 hours. There was no misalignment in the shear retention test of the polarizing plate thus performed. The surface protective film for a polarizing plate according to claim 1 or 2, Wherein the (D) polyalkylene glycol mono(meth) acrylate monomer is selected from the group consisting of polyalkylene glycol mono (meth) acrylate, methoxy polyalkylene glycol (methyl) At least one or more of the group consisting of acrylate and ethoxypolyalkylene glycol (meth) acrylate, the average number of repeats of the alkyleneoxy group constituting the polyalkylene glycol chain is 3~ 14. The diester component in the monomer is 0.2% or less, the water content is 0.1% or less, and the solubility in water is such that the haze value in the state of the 20% aqueous solution is 2% or less. The surface protective film for a polarizing plate according to claim 1 or 2, wherein the (B) hydroxyl group-containing copolymerizable monomer is selected from the group consisting of 8-hydroxyoctyl (meth) acrylate and 6-hydroxyhexyl group. (Meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, N-hydroxy (meth) acrylamide, N-hydroxymethyl (methyl) At least one or more of the group consisting of acrylamide and N-hydroxyethyl (meth) acrylamide, the (C) carboxyl group-containing copolymerizable monomer is selected from (meth)acrylic acid, carboxyl group Ethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2-(methyl) propylene methoxyethyl hexahydrophthalic acid, 2-(methyl) propylene methoxy propyl Hexahydrophthalic acid, 2-(meth)acryloxyethyl phthalate, 2-(meth) propylene methoxyethyl succinic acid, 2-(methyl) propylene oxy ethoxylate At least one or more of the group consisting of ketoic acid, carboxypolycaprolactone mono(meth)acrylate, and 2-(meth)acryloxyethyltetrahydrophthalic acid. The surface protective film for a polarizing plate according to claim 1 or 2, wherein the trifunctional isocyanate compound is an isocyanurate body selected from the group consisting of hexamethylene diisocyanate compound and isophorone diisocyanate. Compound An isocyanurate body, an adduct of a hexamethylene diisocyanate compound, an adduct of an isophorone diisocyanate compound, a biuret of a hexamethylene diisocyanate compound, an isophorone diisocyanate a biuret compound of a compound, an isocyanurate body of a toluene diisocyanate compound, an isocyanurate body of a benzene dimethylene diisocyanate compound, an isocyanurate of a hydrogenated benzene dimethylene diisocyanate compound At least one or more of the compound group consisting of an adduct of a toluene diisocyanate compound, an adduct of a benzene dimethylene diisocyanate compound, and an adduct of a hydrogenated benzene dimethylene diisocyanate compound. The surface protection film for polarizing plates according to the above aspect of the invention, wherein at least one of the (A) alkyl groups has a C4 to C18 (meth) acrylate monomer The (J) antistatic agent is contained in an amount of 100 parts by weight based on 100 parts by weight of the adhesive composition, and is an ionic compound having a melting point of 25 to 50 ° C and being solid at 25 ° C. The surface protective film for a polarizing plate according to claim 1 or 2, wherein for the polarizing plate, the adhesive layer has an adhesive force at a low-speed peeling speed of 0.3 m/min of 0.04 to 0.2 N/25 mm at a high speed. The adhesive force at a peeling speed of 30 m/min was 2.0 N/25 mm or less. The surface protective film for polarizing plates according to the first or second aspect of the invention, wherein the adhesive layer has a surface resistivity of 9.0×10 ⁺¹¹ Ω/□ or less and a peeling static voltage of ±0 to 0.5 kV. The surface protective film for polarizing plates according to the first or second aspect of the invention, wherein an antistatic treatment and an antifouling treatment are performed on the opposite side of the resin film on the side on which the adhesive layer is formed.