TWI744237B - 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℃, the surface-protective film for polarizing plate attached in the polarizing plate does not have dislocation.

Description

Surface protective film for polarizer

The present invention relates to a surface protective film for polarizing plates. In more detail, it relates to a surface protective film for polarizers, which has an excellent balance of adhesive force at low and high peel speeds, even if the adhesive force is small, the adhesion to the polarizer is excellent, durability, and reworkability And antistatic performance is also excellent.

Conventionally, in the manufacturing process of optical components, such as a polarizing plate and a phase difference plate which are components which comprise a liquid crystal display, the surface protection film for temporarily protecting the surface of an optical component is stuck. This surface protective film is only used in the steps of manufacturing optical components, and when the optical components are mounted on a liquid crystal display, they are peeled and removed from the optical components. Since such a surface protection film for protecting the surface of an optical component is used only in the manufacturing process, it is usually called a step film.

The surface protection film used in the step of manufacturing the optical component has an adhesive layer formed on one side of the optically transparent polyethylene terephthalate (PET) resin film, but it is bonded to the optical Before components, a peel-off film for protecting the adhesive layer is attached to the adhesive layer.

In addition, optical components such as polarizers and retardation plates are laminated with a surface protective film, and product inspections accompanied by optical evaluation of the display ability, hue, contrast, and foreign matter mixing of the liquid crystal display panel are performed. Therefore, the surface protective film is inspected. Performance needs In terms of requirements, it is required that no air bubbles or foreign matter adhere to the adhesive layer.

In addition, in recent years, when the surface protective film is peeled off from optical components such as polarizers and retardation plates, peeling static electricity generated by the static electricity generated when the adhesive layer is peeled 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 bonding the surface protection film to optical components such as polarizers and retardation plates, the surface protection film may be temporarily peeled off for various reasons, and then the surface protection film may be re-bonded again. Therefore, it is required in this case Easy to peel from the optical parts of the adherend (re-operability).

In addition, when the surface protective film is finally peeled off from optical components such as polarizers and retardation plates, it is required to be able to peel off quickly. That is, it is required to be able to peel off quickly even by high-speed peeling, and the change in adhesion with the peeling speed is small.

As such, in recent years, as performance requirements for the adhesive layer constituting the surface protective film, from the viewpoint of ease of use when using the surface protective film, it is necessary: (i) In the low-speed peeling speed and the high-speed peeling speed, Achieve a balance of adhesion; (ii) excellent antistatic performance; (iii) re-operability, etc.

For example, with respect to (i) achieving a balance of adhesive force between a low-speed peeling speed and a high-speed peeling speed, the following proposals are known.

A copolymer of an alkyl (meth)acrylate having an alkyl group with 7 or less carbon atoms and a copolymerizable compound containing a carboxyl group as the main component, and the acrylic acid obtained by crosslinking it with a crosslinking agent In this type of adhesive layer, there is a problem that the adhesive transfers and adheres to the adherend in the case of long-term adhesion, or the adhesive force to the adherend increases with time. In order to avoid these problems, it is known to arrange the adhesive layer as follows: use (methyl) having an alkyl group with 8 to 10 carbon atoms An adhesive layer in which a copolymer of an alkyl acrylate and a copolymerizable compound having an alcoholic hydroxyl group is crosslinked with a crosslinking agent (Patent Document 1).

In addition, it is also proposed to arrange the following adhesive layer: a small amount of a copolymer of alkyl (meth)acrylate and a carboxyl-containing copolymerizable compound is added to the same copolymer as above, and it is crosslinked by a crosslinking agent Treated adhesive layer. However, when the above-mentioned adhesive layer is used for surface protection of a plastic board with a low surface tension and a smooth surface, there is a problem of peeling phenomenon such as floating due to heating during processing or storage, or in the handicraft industry. The problem of poor re-peelability during high-speed peeling.

In order to solve these problems, an adhesive composition has been proposed. A) an alkyl (meth)acrylate having an alkyl (meth)acrylate having an alkyl group with 8 to 10 carbon atoms as the main component is proposed. To 100 parts by weight of the ester, b) 1 to 15 parts by weight of carboxyl group-containing copolymerizable compound, c) 3 to 100 parts by weight of vinyl ester of aliphatic carboxylic acid having 1 to 5 carbon atoms are added to the monomer mixture In the copolymer of, a crosslinking agent equal to or greater than the carboxyl group of the above-mentioned component b) is added (Patent Document 2).

In the adhesive composition described in Patent Document 2, peeling phenomenon such as floating does not occur during processing or storage, and the increase of the adhesive force over time is small, and the repeelability is excellent. It is stored for a long time, especially in a high temperature environment. If it is stored for a long time under low pressure, it can be peeled off with a small force. At this time, no glue residue will occur on the adherend, and it can be peeled off with a small force even during high-speed peeling.

In addition, regarding (ii) excellent antistatic performance, as a method for imparting antistatic performance to a surface protective film, a method of incorporating an antistatic agent into a base film, and the like are disclosed. As antistatic agents, for example, (a) quaternary ammonium salts, pyridinium salts, and various cationic antistatic groups having cationic groups such as 1-3 amino groups are disclosed. (B) Anionic antistatic agents with anionic groups such as sulfonate groups, sulfate ester bases, phosphate ester bases, and phosphite groups, and (c) amphoteric antistatic agents such as amino acids and aminosulfates Electrostatic agents, (d) nonionic antistatic agents such as amino alcohols, glycerols, polyethylene glycols, etc., (e) polymer antistatic agents in which the above-mentioned various antistatic agents are polymerized, etc. ( Patent Document 3).

In addition, in recent years, it has been proposed to include the above-mentioned antistatic agent in the base film, or to directly include the above-mentioned antistatic agent in the adhesive layer without coating on the surface of the base film.

In addition, with regard to (iii) reworkability, for example, an adhesive composition is proposed in which 0.0001-10 parts by weight of a curing agent of an isocyanate compound and a specific silicon are added to an acrylic resin with respect to 100 parts by weight of the acrylic resin. Acid salt oligomer (Patent Document 4).

In Patent Document 4, an alkyl acrylate with an alkyl group of about 2 to 12 carbon atoms or an alkyl methacrylate with an alkyl group of about 4 to 12 carbon atoms is used as the main monomer component, for example , May contain other functional group-containing monomer components such as carboxyl group-containing monomers. Generally, it is better to contain 50% by weight or more of the above-mentioned main monomer, or the content of the functional group-containing monomer component is 0.001 to 50% by weight, preferably 0.001 to 25% by weight, and more preferably 0.01 to 25% by weight. The adhesive composition of Patent Document 4 has small changes over time in cohesive force and adhesive force even under high temperature or high temperature and high humidity, and exhibits excellent effects on the adhesive force to curved surfaces, and thus has reworkability.

Generally, if the adhesive layer has a soft property, adhesive residue is likely to occur, and reworkability is likely to decrease. That is, it is difficult to peel off at the time of erroneous bonding, and re-attachment tends to become difficult. Therefore, it is considered that in order to make it reworkable, it is necessary to crosslink the monomer having a functional group such as a carboxyl group in the main agent so that the adhesive layer has a certain hardness.

Prior art literature Patent literature

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

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

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

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

In recent years, large-screen displays such as liquid crystal displays have been rapidly developed. However, with the larger screen of the liquid crystal display, new problems have arisen in the steps of manufacturing the components of the liquid crystal display. For example, with regard to a surface protective film for a polarizing plate that is attached to the surface of the polarizing plate to protect the polarizing plate, the following problems have arisen.

In the prior art, in the manufacturing process of the polarizing plate as a component of the liquid crystal display, after the surface protective film is attached to the polarizing plate as the adherend, when the surface protective film is peeled from the polarizing plate, there is a demand for easy peeling , By making the adhesive force of the adhesive layer formed on the surface protective film small to meet this requirement.

However, if the adhesive force of the adhesive layer is made small and the surface protection film is easily peeled from the adherend, the adhesion force of the surface protection film to the polarizer is reduced. Therefore, with the large screen of the liquid crystal display, the When the size is increased in a larger area than in the past, there is a problem that the surface protective film peels off at the end of the polarizing plate.

The present invention is made in view of the above situation, and its technical problem lies in To provide a surface protective film for polarizers, which has an excellent balance of adhesion at low and high-speed peeling speeds, even if the adhesive force is small, the adhesion to the polarizer is good, durability, reworkability and antistatic Excellent performance.

In order to solve this technical problem, the present invention provides a surface protective film for polarizers, which is a surface protective film for polarizers having an adhesive layer formed on one side of a resin film, and the adhesive layer is made of acrylic polymer, The adhesive composition of a crosslinking agent and an antistatic agent is crosslinked, and the surface protective film for polarizers is characterized in that the acrylic polymer is composed of: (A) ( At least one or more of the meth)acrylate monomers, (B) at least one or more of the copolymerizable monomers containing a hydroxyl group, (C) at least one or more of the copolymerizable monomers containing a carboxyl group, (D) poly At least one of polyalkylene glycol mono(meth)acrylate monomers, (E) a nitrogen-containing vinyl monomer without a hydroxyl group or an alkoxy-containing alkyl (meth)acrylate At least one of the monomers is copolymerized to form a copolymer composition, the crosslinking agent is a trifunctional isocyanate compound, and the adhesive composition further contains (F) a polyether-modified silicone with an HLB value of 7-12 The alkane compound is laminated on the polarizer which has been treated with AG and cut into the size of 25mm wide×35mm long on the surface protective film for polarizing plate, applying a load of 500g, and leaving it for 24 hours in an environment at a temperature of 23°C. There is no dislocation in the shear retention test of the polarizer.

In addition, the present invention provides a surface protective film for polarizers, which is a surface protective film for polarizers having an adhesive layer formed on one side of a resin film, and the adhesive layer is composed of an acrylic polymer, a crosslinking agent, It is formed by cross-linking an adhesive composition of an antistatic agent, and the surface protective film for a polarizer is characterized by: The acrylic polymer is composed of: (A) 100 parts by weight of at least one of the (meth)acrylate monomers of C4-C18 alkyl groups, and (B) a copolymerizable monomer containing a hydroxyl group. The total amount of at least one or more parts in the body is 2 to 10 parts by weight, (C) the total amount of at least one or more in the carboxyl-containing copolymerizable monomer is 0.05 to 0.3 parts by weight, (D) the polyalkylene glycol mono( The total amount of at least one or more of the meth)acrylate monomers is 3-40 parts by weight, (E) a nitrogen-containing vinyl monomer without a hydroxyl group or an alkoxy-containing alkyl (meth)acrylate monomer The crosslinking agent is a trifunctional isocyanate compound, and the number of carbon atoms relative to the (A) alkyl group is C4 to C18. The total amount of at least one or more of the (meth)acrylate monomers is 100 parts by weight, and the adhesive composition further contains (F) a polyether modified with an 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 siloxane compounds are bonded to the polarizing plate that has been treated with AG, and the surface protective film for the polarizing plate cut into a size of 25 mm wide x 35 mm long is applied, and a load of 500 g is applied in an environment at a temperature of 23°C. After being left for 24 hours, there was no misalignment in the shear retention test of the polarizing plate.

The above-mentioned (D) polyalkylene glycol mono(meth)acrylate monomer is selected from polyalkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol (meth)acrylic acid At least one or more of the compound group consisting of ester and ethoxy polyalkylene glycol (meth)acrylate, the average repeating number of alkylene oxide (alkylene oxide) constituting the polyalkylene glycol chain It is 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 a 20% aqueous solution.

The above-mentioned (B) hydroxyl-containing copolymerizable monomer is selected from 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate Base) acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-hydroxyethyl(meth) At least one or more of the compound group composed of acrylamide is preferred.

The above-mentioned (C) carboxyl-containing copolymerizable monomer is selected from (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxy Ethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(methyl) )Acrylic oxyethyl succinic acid, 2-(meth)acryloxyethyl maleic acid, carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acryloxyethyl At least one or more of the group of compounds composed of tetrahydrophthalic acid is preferred.

The above-mentioned trifunctional isocyanate compound is selected from an isocyanurate body of a hexamethylene diisocyanate compound, an isocyanurate body of an isophorone diisocyanate compound, and an adduct of a hexamethylene diisocyanate compound , Adduct of isophorone diisocyanate compound, biuret of hexamethylene diisocyanate compound, biuret of isophorone diisocyanate compound, isocyanurate of toluene diisocyanate compound , Isocyanurate body of xylylene diisocyanate compound, isocyanurate body of hydrogenated xylylene diisocyanate compound, adduct of toluene diisocyanate compound, xylylene diisocyanate It is preferable that at least one compound is selected from the group consisting of an adduct of a compound and an adduct of a hydrogenated xylylene diisocyanate compound.

The adhesive composition contains 0.01 to 5.0 parts by weight relative to 100 parts by weight of the total amount of at least one or more of the (meth)acrylate monomers having C4 to C18 carbon atoms in the alkyl group (A) The above-mentioned (J) antistatic agent is preferably an ionic compound that has a melting point of 25-50°C and is solid at 25°C.

For the polarizer, the adhesive layer has an adhesive force of 0.04~0.2N/25mm at a low-speed peeling speed of 0.3m/min, and preferably an adhesive force of 2.0N/25mm or less at a high-speed peeling speed of 30m/min.

The surface resistivity of the adhesive layer is 9.0×10 ⁺¹¹ Ω/□ or less, and the peeling static voltage is preferably ±0~0.5kV.

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

According to the present invention, it is possible to provide a surface protective film for a polarizer, which has an excellent balance of adhesive force at a low peeling speed and a high peeling speed, even if the adhesive force is small, the adhesive force to the polarizer is good, durability, and reworkability Excellent performance and antistatic properties.

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

The surface protective film for polarizers of the present invention is a surface protective film for polarizers in which an adhesive layer is formed on one side of a resin film, and the adhesive layer is made of an acrylic polymer, a crosslinking agent, and an antistatic agent. The surface protective film for polarizers is formed by cross-linking the agent composition, and the characteristic of the acrylic polymer is that the acrylic polymer is composed of: At least one or more, (B) at least one or more of the copolymerizable monomers containing a hydroxyl group, (C) at least one or more of the copolymerizable monomers containing a carboxyl group, (D) polyalkylene glycol mono(methyl) At least one of acrylate monomers, (E) hydroxy-free nitrogen-containing ethylene The adhesive composition is composed of a copolymer formed by copolymerizing at least one of monomers or alkoxy-containing alkyl (meth)acrylate monomers, the crosslinking agent is a trifunctional isocyanate compound, and the adhesive composition is further Containing (F) a polyether-modified silicone compound with an HLB value of 7 to 12, glued to the polarizer subjected to AG treatment, and cut into the size of 25mm x 35mm in length, the surface protective film for the polarizer is applied With a load of 500 g and left for 24 hours in an environment at a temperature of 25°C, there was no misalignment in the shear retention test of the polarizing plate conducted therefrom.

In addition, the surface protective film for polarizers of the present invention is a surface protective film for polarizers in which an adhesive layer is formed on one side of a resin film, and the adhesive layer is composed of acrylic polymer, crosslinking agent, and antistatic agent. The adhesive composition is cross-linked, and the surface protective film for polarizers is characterized in that the acrylic polymer is composed of: (A) alkyl (meth)acrylate monomers with C4-C18 carbon atoms 100 parts by weight of at least one or more of the total, (B) 2-10 parts by weight of at least one of the copolymerizable monomers containing hydroxyl groups, and (C) at least one of the copolymerizable monomers containing carboxyl groups The total amount of the above is 0.05 to 0.3 parts by weight, (D) the total amount of at least one or more of the polyalkylene glycol mono(meth)acrylate monomers is 3 to 40 parts by weight, and (E) contains no hydroxyl group At least one of nitrogen vinyl monomers or alkoxy-containing alkyl (meth)acrylate monomers is composed of copolymers with a total amount of 0.1-20 parts by weight. The crosslinking agent is trifunctional 100 parts by weight of the total amount of at least one of the (meth)acrylate monomers having C4 to C18 carbon atoms relative to the (A) alkyl group of the isocyanate compound, the adhesive composition is further 0.001 to 0.5 parts by weight containing at least one of (F) polyether modified silicone compounds with an HLB value of 7 to 12, bonded to the polarizer treated with AG, and cut into a width of 25mm × a length of 35mm Size of the polarizer with surface protection A load of 500 g was applied to the film, and it was left for 24 hours in an environment at a temperature of 23° C. There was no misalignment in the shear retention test of the polarizing plate conducted therefrom.

Examples of (A) alkyl (meth)acrylate monomers having C4 to C18 carbon atoms include butyl (meth)acrylate, isobutyl (meth)acrylate, and pentyl (meth)acrylate. Ester, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (methyl) ) Nonyl acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate , Tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate , Octadecyl (meth)acrylate, myristyl (meth)acrylate, isomyristyl (meth)acrylate, cetyl (meth)acrylate, isocetyl (meth)acrylate, ( Stearyl meth)acrylate, isostearyl (meth)acrylate, etc.

(B) The copolymerizable monomer containing a hydroxyl group includes 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, Hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, or N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N- Hydroxyethyl (meth)acrylamide and other hydroxyl-containing (meth)acrylamides.

Selected from 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N -Hydroxy (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, at least one of the group of compounds consisting of The above is better.

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

(C) The copolymerizable monomer containing a carboxyl group is selected from (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethyl Hexahydrophthalic acid, 2-(meth)acryloxypropylhexahydrophthalic acid, 2-(meth)acryloxyethyl phthalic acid, 2-(meth)propylene Acrylic oxyethyl succinic acid, 2-(meth)acrylic acid oxyethyl maleic acid, carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acryloxyethyl tetra At least one or more of the compound group composed of hydrogen phthalic acid is preferred.

(C) is contained in the total amount of at least one or more of the (meth)acrylate monomers having C4 to C18 carbon atoms of the (A) alkyl group in a ratio of 0.05 to 0.3 parts by weight in total 100 parts by weight At least one or more of the copolymerizable monomers containing a carboxyl group is preferably contained in a ratio of 0.05 to 0.25 parts by weight, and particularly preferably contained in a ratio of 0.05 to 0.2 parts by weight.

As the (D) polyalkylene glycol mono(meth)acrylate monomer, as long as it is among the multiple hydroxyl groups possessed by the polyalkylene glycol, one hydroxyl group is esterified in the form of (meth)acrylate The chemical compound is sufficient. Since the (meth)acrylate group becomes a polymerizable group, it can be copolymerized with the main agent polymer. The other hydroxyl groups may be OH itself, or may be alkyl ethers such as methyl ether or ethyl ether, or saturated carboxylic acid esters such as acetate.

Examples of the alkylene group possessed by the polyalkylene glycol include ethylene, propylene, butylene, etc., but are not limited to these. The polyalkylene glycol may be a copolymer of two or more polyalkylene glycols among polyethylene glycol, polypropylene glycol, and polybutylene glycol. Examples of polyalkylene glycol copolymers include polyethylene glycol-polypropylene glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, and polyethylene glycol-polypropylene glycol-polybutylene glycol. Diol, etc., the copolymer may be a block copolymer or a random copolymer.

(D) The average repeating number of the alkyleneoxy group constituting the polyalkylene glycol chain of the polyalkylene glycol mono(meth)acrylate monomer is preferably 3-14. The "average number of repeating alkyleneoxy groups" refers to the "polyalkylene glycol chain" part contained in the molecular structure of the (D) polyalkylene glycol mono(meth)acrylate monomer, The average number of repeating alkyleneoxy units.

As (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 state of an aqueous solution is preferably 2% or less.

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

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

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

In addition, in this specification, the haze value of a 20% aqueous solution is a value obtained by adding the aqueous solution to a quartz cell with an optical path length of 10 mm and measuring with a haze meter. This index is used as the degree of hydrophilicity of (D) polyalkylene glycol mono(meth)acrylate monomers, and is used to select monomers with high hydrophilicity that can obtain solutions without white turbidity even at high concentrations And the imported indicators.

(D) Polyalkylene glycol mono(meth)acrylate monomer is selected from polyalkylene glycol mono(meth)acrylate, methoxy polyalkylene glycol (meth)acrylic acid At least one or more of the compound group consisting of ester and ethoxy polyalkylene glycol (meth)acrylate is preferable.

More specifically, polyethylene glycol-mono(meth)acrylate, polypropylene glycol-mono(meth)acrylate, polybutylene glycol-mono(meth)acrylate, polyethylene glycol- Polypropylene glycol-mono(meth)acrylate, polyethylene glycol-polybutylene glycol-mono(meth)acrylate, polypropylene glycol-polybutylene glycol-mono(meth)acrylate, polyethylene glycol- Polypropylene glycol-polybutylene glycol-mono(meth)acrylate; methoxypolyethylene glycol-(meth)acrylate, methoxypolypropylene glycol-(meth)acrylate, methoxypolybutylene Alcohol-(meth)acrylate, methoxy-polyethylene glycol-polypropylene glycol-(meth)acrylate, methoxy-polyethylene glycol-polybutylene glycol-(meth)acrylate, methyl Oxygen-polypropylene glycol-polybutylene glycol-(meth)acrylate, methoxy-polyethylene glycol-polypropylene glycol-polybutylene glycol-(meth)acrylate; ethoxypolyethylene glycol- (Meth)acrylate, ethoxy polypropylene glycol-(meth)acrylate, ethoxy polybutylene glycol-(meth)acrylate, ethoxy-polyethylene glycol-polypropylene glycol-(methyl) ) Acrylate, ethoxy-polyethylene glycol-polybutylene glycol-(meth)acrylate, ethoxy-polypropylene glycol-polybutylene glycol-(meth)acrylate, ethoxy-polyethylene Glycol-poly Propylene glycol-polybutylene glycol-(meth)acrylate etc.

(D) is contained in the total amount of at least one or more of the (meth)acrylate monomers having C4 to C18 carbon atoms of the (A) alkyl group in a ratio of 3 to 40 parts by weight in total 100 parts by weight At least one of the polyalkylene glycol mono(meth)acrylate monomers is preferably contained in a ratio of 3 to 30 parts by weight, and particularly preferably contained in a ratio of 5 to 30 parts by weight.

The acrylic polymer may further contain (E) at least one of a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkoxy-containing alkyl (meth)acrylate monomer. In (E), examples of (E-1) nitrogen-containing vinyl monomers include amide bond-containing vinyl monomers, amino-containing vinyl monomers, and ethylene having a nitrogen-containing heterocyclic structure. Based monomers and so on. 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 with N-vinyl substituted heterocyclic structures such as vinyl lauryl amine; N-(meth)acryloyl morpholine, N-(meth)acryloyl piperazine, N-(meth)acryloyl aziridine, N-(meth)acryloyl azetidine, N-(meth)acryloyl pyrrolidine, N-(meth)acryloyl aziridine Rings with N-(meth)acryloyl substituted heterocyclic structures such as pyridine, N-(meth)acryloyl azepanes, N-(meth)acryloyl azepanes, etc. Nitrogen-like vinyl compounds; N-cyclohexylmaleimide, N-phenylmaleimide and other cyclic nitrogen vinyl groups containing heterocyclic structures with nitrogen atoms and ethylenic unsaturated bonds in the ring Compound; (meth)acrylamide, N-methyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-tert-butyl (methyl) 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-methan (Meth)acrylamide, N-methyl-N-propyl(meth)acrylamide, N-methyl-N-isopropyl(meth)acrylamide and other dialkyl substituted (meth)acrylamides Yl)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 , Tert-butylaminoethyl (meth)acrylate and other dialkylamino (meth)acrylates; N,N-dimethylaminopropyl (meth)acrylamide, N,N-diethyl Aminopropyl(meth)acrylamide, N,N-dipropylaminopropyl(meth)acrylamide, N,N-diisopropylaminopropyl(meth)acrylamide, N- Ethyl-N-methylaminopropyl(meth)acrylamide, N-methyl-N-propylaminopropyl(meth)acrylamide, N-methyl-N-isopropylaminopropyl N,N-dialkyl substituted aminopropyl (meth)acrylamide; N-vinylformamide, N-vinylacetamide, N-vinyl-N -N-vinyl amides such as methylacetamide; N-methoxymethyl(meth)acrylamide, N-ethoxyethyl(meth)acrylamide, N-butyl Oxymethyl (meth)acrylamide, diacetone acrylamide, N,N-methylenebis(meth)acrylamide, etc. (meth)acrylamides; (meth)acrylonitrile, etc. Unsaturated carboxylic acid nitriles, etc.

As (E-1) the nitrogen-containing vinyl monomer, it is preferred that it does not contain a hydroxyl group, and it is more preferred that it does not contain a hydroxyl group and a carboxyl group. As such monomers, the monomers listed above, for example: acrylic monomers containing N,N-dialkyl substituted amino groups or N,N-dialkyl substituted amide groups; N-vinyl-2- Pyrrolidone, N-vinylcaprolactam, N-vinyl-2-piperidone and other N-vinyl substituted lactams; N-(meth)acryloylmorpholine or N-(methyl) N-(meth)acryloyl substituted cyclic amines such as acryloylpyrrolidine are preferred.

In (E), examples of (E-2) alkoxy-containing alkyl (meth)acrylate monomers include 2-methoxyethyl (meth)acrylate and 2-ethoxy Ethyl (meth)acrylate, 2-propoxyethyl (meth)acrylate, 2-isopropoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate Ester, 2-methoxypropyl (meth)acrylate, 2-ethoxypropyl (meth)acrylate, 2-propoxypropyl (meth)acrylate, 2-isopropoxy Propyl (meth)acrylate, 2-butoxypropyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate , 3-propoxypropyl (meth)acrylate, 3-isopropoxypropyl (meth)acrylate, 3-butoxypropyl (meth)acrylate, 4-methoxybutane Base (meth)acrylate, 4-ethoxybutyl (meth)acrylate, 4-propoxybutyl (meth)acrylate, 4-isopropoxybutyl (meth)acrylate , 4-Butoxybutyl (meth)acrylate, etc.

These alkoxy group-containing alkyl (meth)acrylate monomers have a structure in which the alkyl group atoms in the alkyl group (meth)acrylate are substituted with alkoxy groups.

(A) 100 parts by weight of the total amount of at least one or more of the (meth)acrylate monomers having C4 to C18 carbon atoms in the alkyl group, (E) a nitrogen-containing vinyl monomer that does not contain a hydroxyl group or Among alkoxy-containing alkyl (meth)acrylate monomers It is preferable to contain at least one or more of the total amount of 0.1-20 parts by weight, more preferably 0.3-10 parts by weight, and particularly preferably 0.3-8 parts by weight. One or two or more of (E-1) a nitrogen-containing vinyl monomer containing no hydroxyl group and (E-2) an alkoxy-containing alkyl (meth)acrylate monomer can be used separately.

The adhesive composition of the present invention may contain (F) a polyether-modified silicone compound having an HLB value of 7-12. The polyether-modified silicone compound is a silicone compound with a polyether group. In addition to the usual silicone unit [-SiR ¹ ₂ -O-], it also includes a polyether group-containing silicone unit [ -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 or aryl groups, etc. ( Terminal group). Examples of the polyether group include polyoxyalkylene groups such as polyoxyethylene [(C ₂ H ₄ O) _n ] or polyoxypropylene [(C ₃ H ₆ O) _n ].

(F) is contained in 100 parts by weight of the total amount of at least one or more of the (meth)acrylate monomers having C4 to C18 carbon atoms in the alkyl group (A) in a total amount of 0.001 to 0.5 parts by weight At least one polyether-modified silicone compound having an HLB value of 7 to 12 is preferably at least one, and more preferably 0.01 to 0.5 parts by weight. The HLB value refers to, for example, the hydrophilic-lipophilic balance (hydrophilic-lipophilic ratio) prescribed in JIS K3211 (Terms of Surfactant).

The polyether-modified silicone compound can be obtained, for example, by grafting an organic compound having an unsaturated bond and a polyoxyalkylene group to the main chain of a polyorganosiloxane having a hydrogenated silyl group by a hydrosilation reaction. Specifically, dimethylsiloxane-methyl(polyoxyethylene)siloxane copolymer, dimethylsiloxane-methyl(polyoxyethylene)siloxane-methanone Base (polyoxypropylene) silicone copolymer, two Methylsiloxane-methyl (polyoxypropylene) siloxane polymer, etc. The HLB value of the polyether-modified silicone compound can be adjusted by selecting the ratio of the polyether group to the silicone group. By adding (F) a polyether-modified silicone compound with an HLB value of 7-12 to the adhesive composition, the adhesive force and reworkability of the adhesive can be improved.

As a trifunctional isocyanate compound, what is necessary is just to be at least 1 type, or 2 or more types selected from the polyisocyanate compound which has 3 isocyanate (NCO) groups in 1 molecule. The polyisocyanate compound has classifications such as aliphatic isocyanate, aromatic isocyanate, acyclic isocyanate, and alicyclic isocyanate, and any of them may be used.

Examples of trifunctional isocyanate compounds include biuret-modified bodies or isocyanurate-modified bodies of bifunctional isocyanate compounds (compounds having two NCO groups in one molecule), and trimethylolpropane ( Adducts (modified polyols) of trivalent or higher polyols (compounds having at least 3 or more OH groups in one molecule) such as TMP or glycerol.

The trifunctional isocyanate compound is selected from the group consisting of isocyanurate body of hexamethylene diisocyanate compound, isocyanurate body of isophorone diisocyanate compound, and adduct of hexamethylene diisocyanate compound , Adduct of isophorone diisocyanate compound, biuret of hexamethylene diisocyanate compound, biuret of isophorone diisocyanate compound, isocyanurate of toluene diisocyanate compound , Isocyanurate body of xylylene diisocyanate compound, isocyanurate body of hydrogenated xylylene diisocyanate compound, adduct of toluene diisocyanate compound, xylylene diisocyanate Compound adduct, hydrogenated xylylene diisocyanate compound At least one or more of the compound group constituted by the adduct is preferred.

(A) The total amount of at least one or more of the (meth)acrylate monomers with C4 to C18 carbon atoms of the alkyl group is 100 parts by weight, and the total amount is 0.1-10 parts by weight. At least one kind of isocyanate compound is preferable, and it is more preferable to contain it in the ratio of 0.1-6 weight part.

In the case of using a polyisocyanate compound as a crosslinking agent, the crosslinking catalyst may be a substance that acts as a catalyst for the reaction between the acrylic polymer and the crosslinking agent (crosslinking reaction), and amines such as tertiary amines may be mentioned. Organometallic compounds such as class compounds, metal chelate compounds, organic tin compounds, organic lead compounds, and organic zinc compounds.

Examples of tertiary amines include trialkylamine, N,N,N',N'-tetraalkyldiamine, N,N-dialkylamino alcohol, triethylenediamine, morpholine derivatives, piperidine Oxazine derivatives and so on.

1，n

0。在m為2以上的情况下，m個的L可以為相同配體，也可以為不同配體。在n為2以上的情况下，n個的X可以為相同配體，也可以為不同配體。 As a metal chelate compound, it is a compound in which one or more multidentate ligands L are bonded to the central metal atom M. The metal chelate compound may have one or more monodentate ligands X bound to the metal atom M, or not. For example, when the general formula of a metal chelate compound in which the metal atom M is 1 is expressed as M(L) _m (X) _n , m

1, n

0. When m is 2 or more, the m pieces of L may be the same ligand or different ligands. When n is 2 or more, the n pieces 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, Sn, and the like.

Examples of the multidentate ligand L include methyl acetoacetate, ethyl acetoacetate, octyl acetate, oleyl acetoacetate, lauryl acetoacetate, and acetylacetate. Β-ketoesters such as stearyl ester, or β-diketones such as acetone (also known as 2,4-pentanedione), 2,4-hexanedione, and benzacetone. They are keto-enol tautomer compounds, and in the multidentate ligand L, they may also be enolates (for example, acetylacetonates) formed by deprotonation of enols.

Examples of monodentate ligand X include halogen atoms such as chlorine atom and bromine atom, pentanyl, hexyl, 2-ethylhexyl, octyl, nonyl, decyl, dodecyl, Alkoxy groups such as octadecanoyl group, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, butoxy group, and the like.

Specific examples of metal chelate compounds include tris(2,4-pentanedionyl) iron (III), iron triacetone, titanium triacetone, ruthenium triacetone, and diacetone Zinc, aluminum triacetate, zirconium tetraacetone, tris(2,4-hexanedione) iron(III), bis(2,4-hexanedione) zinc, tris(2,4-hexyl) Diketone) titanium, tris(2,4-hexanedione)aluminum, tetra(2,4-hexanedione)zirconium, etc.

Examples of the organotin compound include dialkyl tin oxide, or a fatty acid salt of dialkyl tin, and a fatty acid salt of 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, etc. are preferred. As the organotin compound, at least one compound selected from the group consisting of dioctyltin oxide and dioctyltin dilaurate is preferred.

The total amount of at least one or more of the (meth)acrylate monomers having C4 to C18 carbon atoms relative to (A) alkyl group is 100 parts by weight, and the crosslinking catalyst is contained in a ratio of 0.001 to 0.5 parts by weight in total. At least one of them is preferable.

As the keto-enol tautomer compound, acetyl ethyl Β-ketoesters such as methyl ester, ethyl acetate, octyl acetate, oleyl acetate, lauryl acetate, stearyl acetylacetate, etc., or acetone, 2,4- Β-diketones such as hexanedione and benzophenone. The keto-enol tautomer compound is used in an adhesive composition using a polyisocyanate compound as a crosslinking agent. By blocking the isocyanate group of the crosslinking agent, the combination of the adhesive after the addition of the crosslinking agent can be suppressed Excessive viscosity rise or gelation of the substance prolongs the pot life of the adhesive composition.

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

(A) The total amount of at least one or more of the (meth)acrylate monomers with C4 to C18 carbon atoms of the alkyl group is 100 parts by weight, and the total amount of the ketone-ene is contained in a ratio of 0.1 to 300 parts by weight. At least one of the alcohol tautomer compounds is preferred, and the ratio of 1.0 to 30.0 parts by weight is more preferred.

Contrary to the crosslinking catalyst, the keto-enol tautomer compound has the effect of inhibiting crosslinking, so it is better to appropriately set the ratio of the keto-enol tautomer compound to the crosslinking catalyst. In order to extend 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 25-50°C and is preferably an ionic compound that is solid at 25°C.

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

(J) The antistatic agent includes an ionic compound that has a melting point of 25 to 50°C and is solid at 25°C in the adhesive composition.

As an ionic compound having a melting point of 25-50°C and a solid at 25°C, it is an ionic compound having a cation and an anion. The cations include pyridinium cation, imidazolium cation, pyrimidinium cation, and pyrazolium cation. cation, pyrrolidinium cation, ammonium cation or phosphonium cation containing nitrogen cation, sulfonium cation, a phosphate hexafluoride anion (PF ₆ ^-), thiocyanate (SCN ^-), alkyl benzene sulphonate ^{_{(RC 6 H 4 SO 3 -}} ), perchlorate (ClO ₄ ^-), tetrafluoroborate (BF ₄ ^-), bis (fluorinated sulfonic acyl) acyl imide salt (FSI), bis (tri Compounds of inorganic or organic anions such as fluoromethanesulfonyl)iminium salt (TFSI) and trifluoromethanesulfonate (TF). It is preferably a solid at room temperature (for example, 25°C), and a compound with a melting point of 25-50°C can be obtained by selecting the chain length of the alkyl group or the position and number of substituents. The cation is preferably a quaternary nitrogen-containing cation. Examples include 1-alkylpyridinium (the carbon atoms at positions 2 to 6 may have or may not be substituted.) and other quaternary pyridinium cations, or 1, Quaternary imidazolium cations such as 3-dialkylimidazolium (the carbon atoms at positions 2, 4, and 5 may be substituted or unsubstituted.) and quaternary ammonium cations such as tetraalkylammonium.

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

(J) Specific examples of antistatic agents are not particularly limited, but specific examples of ionic compounds that have a melting point of 25-50°C and are solid at 25°C Examples include 1-octylpyridinium hexafluoride phosphate, 1-nonylpyridinium hexafluoride phosphate, 2-methyl-1-dodecylpyridinium hexafluoride phosphate, 1 -Octylpyridinium dodecylbenzenesulfonate, 1-dodecylpyridinium thiocyanate, 1-dodecylpyridinium dodecylbenzenesulfonate, 4-methyl-1 -Octylpyridinium hexafluoride phosphate, etc.

Furthermore, as other components, copolymerizable (meth)acrylic monomers containing alkylene groups, (meth)acrylamide monomers, dialkyl substituted acrylamide monomers, and surface-active Conventional additives such as curing agents, curing accelerators, plasticizers, fillers, curing retarders, processing aids, anti-aging agents, and antioxidants. This substance can be used alone or two or more of them can be used at the same time.

The acrylic polymer used in the adhesive composition of the present invention is composed of: (A) at least one or more of (meth)acrylate monomers with C4 to C18 carbon atoms in the alkyl group, and (B) containing hydroxyl groups At least one of the copolymerizable monomers and (C) at least one of the copolymerizable monomers containing a carboxyl group are copolymerized. In addition, the acrylic polymer may also be composed of: (A) at least one of (meth)acrylate monomers with C4 to C18 carbon atoms in the alkyl group, and (B) at least one of the copolymerizable monomers containing hydroxyl groups. One or more, (C) at least one or more of the copolymerizable monomers containing carboxyl groups, (D) at least one of the polyalkylene glycol mono(meth)acrylate monomers, (E) hydroxy-containing At least one or more types of nitrovinyl monomers or alkoxy-containing alkyl (meth)acrylate monomers are copolymerized. The polymerization method of the acrylic polymer is not particularly limited, and appropriate polymerization methods such as solution polymerization and emulsion polymerization can be used.

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

When preparing the acrylic polymer, in order to reduce the incorporation of moisture in the adhesive composition, it is better to perform a polymerization reaction under anhydrous conditions such as solution polymerization using an anhydrous organic solvent. In particular, (D) polyalkylene glycol mono(meth)acrylate monomer has high hydrophilicity, so it is better to use one with a low water content.

In order to prevent the viscosity of the adhesive composition from increasing, the monomers used in the preparation of the acrylic polymer as the main agent should minimize the amount of multifunctional (difunctional or higher) monomers that can function as a crosslinking agent. good. In particular, the diester component corresponding to the (D) polyalkylene glycol mono(meth)acrylate monomer is a di(meth)acrylate of a bifunctional monomer, so the one with less diester components is preferred .

With respect to 100 parts by weight of the acrylic polymer, the acrylic polymer contains (meth)acrylate monomer or (meth)acrylic acid, (meth)acrylamides, etc., in a ratio of 50 to 100 parts by weight Acrylic monomers are preferred.

In addition, the acid value of the acrylic polymer is preferably 0.01 to 8.0. As a result, contamination can be improved, and the performance of preventing the occurrence of glue residue can be improved.

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

The adhesive force of the adhesive layer formed by cross-linking the adhesive composition to the polarizer is 0.04~0.2N/25mm at a low-speed peeling speed of 0.3m/min, and adhesive force at a high-speed peeling speed of 30m/min It is better to be 2.0N/25mm or less. As a result, it is possible to obtain the performance that the adhesive force changes little due to the peeling speed, and it can be peeled off quickly even when peeling off at a high speed. In addition, due to Re-bonding, so even when the surface protective film is temporarily peeled off, it does not require excessive force and easily peels off from the adherend.

The surface resistivity of the adhesive layer formed by crosslinking the adhesive composition is preferably 9.0×10 ⁺¹¹ Ω/□ or less, and the peeling static voltage is preferably ±0~0.5kV. In addition, in the present invention, "±0~0.5kV" means 0~-0.5kV and 0~+0.5kV, which means -0.5~+0.5kV. If the surface resistivity is large, the performance of dissipating static electricity generated by charging at the time of peeling is poor. Therefore, by making the surface resistivity sufficiently small, the peeling static voltage caused by the static electricity generated when the adhesive layer is peeled from the adherend is reduced, and the influence on the electrical control circuit of the adherend can be suppressed.

The gel fraction of the adhesive layer cross-linked by the adhesive composition is preferably 95-100%. With this high gel fraction, the adhesive force at low peeling speeds will not be too large and reduce By eluting unpolymerized monomers or oligomers from acrylic polymers, it can improve reworkability, durability under high temperature and high humidity, and suppress contamination of adherends.

By forming the adhesive layer formed by crosslinking the adhesive composition on one or both sides of the resin film, an adhesive film can be obtained. In addition, the surface protective film for a polarizer of the present invention is a surface protective film in which an adhesive layer formed by crosslinking the adhesive composition is formed on one side of a resin film. The surface protective film for polarizers of the present invention has no dislocation in the shear retention test when it is attached to the polarizer, and has good adhesion to the polarizer despite the low adhesive force, durability, reworkability and antistatic 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, flat (general purpose), anti-glare (AG), and the like. As a protective film material of the surface of a polarizing plate, a TAC type film (triacetyl cellulose type compound), an acrylic type film, etc. are mentioned.

Examples of test conditions for the shear retention force include a load (mass of a weight) of 500 g, an ambient temperature of 23° C., and a standing time of 24 hours. This test condition is suitable as an indicator for judging that the adhesion force to the surface protective film of the polarizing plate is good. The contact area (size) of the surface protection film for a polarizing plate of the polarizing plate with respect to the to-be-adhered body of the shear holding force test is 25 mm×35 mm. The details of the test method (device, etc.) can be based on, for example, the retention test of JIS Z 0237 (testing method for adhesive tapes and adhesive sheets).

As the resin film which becomes the base material of an adhesive layer, or the peeling film (separator) which protects an adhesive surface, resin films, such as a polyester film, etc. can be used.

For the resin film as the base material, antifouling treatment can be performed on the side opposite to the side where the adhesive layer of the resin film is formed, with silicone-based, fluorine-based release agents or coating agents, silica particles, etc. , Implement antistatic treatment by coating or blending antistatic agents.

On the release film, a release treatment is performed with a silicone-based, fluorine-based release agent, etc., on the side that is bonded to the adhesive surface of the adhesive layer.

Example

Hereinafter, the present invention will be described in detail with examples.

<Production of acrylic polymer>

[Example 1]

Introduce nitrogen into the reaction device equipped with a stirrer, thermometer, reflux cooler and nitrogen introduction pipe, and replace the air in the reaction device with nitrogen. Then, 100 parts by weight of 2-ethylhexyl acrylate, 8.0 parts by weight of 8-hydroxyoctyl acrylate, 0.1 part by weight of acrylic acid, and polypropylene glycol monoacrylate (a The average repeating number of alkoxy groups n=12, two of the monomers The ester component is 0.1%, the solubility in water is 0.8% in a 20% aqueous solution, and the water content is 0.05%) 8 parts by weight, 1 part by weight of N-vinylpyrrolidone, and a solvent (acetic acid) Ethyl ester) 60 parts by weight. Then, 0.1 parts by weight of azobisisobutyronitrile as a polymerization initiator was dropped over 2 hours and reacted at 65° C. for 6 hours to obtain an acrylic polymer solution used in Example 1 with a weight average molecular weight of 500,000. A part of the acrylic polymer was extracted and used as a measurement sample of the acid value described later.

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

Except that the composition of the monomers was set to the composition of (A) to (E) of Table 1, in the same manner as the acrylic polymer solution used in the above-mentioned Example 1, obtained for Examples 2 to 8 And the acrylic polymer solutions of Comparative Examples 1 to 4.

<Production of Adhesive Composition and Surface Protective Film>

[Example 1]

To the acrylic polymer solution of Example 1 prepared above, 0.05 parts by weight of polyether-modified silicone compound (HLB value 7), 1.0 part by weight of 1-octylpyridinium hexafluoride phosphate, and ethyl acetate were added. 8.5 parts by weight of acetone, after stirring, 4.0 parts by weight of CORONATE HX (isocyanurate body of hexamethylene diisocyanate compound) and 0.1 parts by weight of titanium triacetone were added and stirred and mixed to obtain the adhesion of Example 1.剂组合物。 Agent composition. The adhesive composition was coated on a release film composed of a polyethylene terephthalate (PET) film coated with a silicone resin, and then the solvent was removed by drying at 90°C to obtain an adhesive layer Adhesive sheet with a thickness of 25μm.

Then, on one side of the antistatic and antifouling polyethylene terephthalate (PET) film on the opposite side of the antistatic and antifouling surface, The adhesive sheet was transferred to obtain the surface protective film of Example 1 having a laminated structure of "PET film with antistatic and antifouling treatment/adhesive layer/release film (PET film coated with silicone resin)".

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

Except that the composition of the additive is set to the composition of (F) to (J) in Table 2, in the same manner as the surface protective film of Example 1 described above, Examples 2 to 8 and Comparative Examples 1 to 4 were obtained. The surface protective film.

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

In addition, the compound name of each component abbreviation used in Table 1 and Table 2 is shown in Table 3 and Table 4. In addition, CORONATE (registered trademark) HX, CORONATE HL, and CORONATE L are the trade names of Polyurethane Industry Co., Ltd., and Takenate (registered trademark) D-140N, D-127N, D-110N, and D-120N are Mitsui Chemicals Co., Ltd. The company's trade name. For the group (D) of Table 3, the value of "n" is the average number of repeating alkyleneoxy groups 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 protection films in Examples 1 to 8 and Comparative Examples 1 to 4 were aged for 7 days at 23°C and 50% RH, and then peeled off the release film (PET film coated with silicone resin) ), the film exposing the adhesive layer was used as a measurement sample for gel fraction and surface resistivity.

Furthermore, the surface protection film exposing the adhesive layer was pasted on the surface of the polarizing plate pasted on the liquid crystal cell through the adhesive layer, and after leaving it for 1 day, 50% Perform autoclave treatment at ℃, 5 atmospheres, 20 minutes, and leave it at room temperature for a further 12 hours, and use it as a measurement sample for adhesion, peeling static voltage, shear retention (dislocation), reoperability, and durability. The polarizing plate of the adherend is a polarizing plate with AG treatment on the surface.

<Gel fraction>

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

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

<Adhesion>

Using a tensile tester, the above-obtained measurement sample (a 25mm wide surface protective film is attached to the surface of the polarizing plate with AG treatment) in the 180° direction at a low speed peeling speed (0.3m/min) and High-speed peeling speed (30m/min) peels off, and the measured peel strength is calculated as the adhesive force (N/25mm).

<Surface resistivity>

After curing, before bonding to the polarizer, peel off the release film (PET film coated with silicone resin) to expose the adhesive layer. Use a resistivity meter HIRESTA UP-HT450 (manufactured by Mitsubishi Chemical Analytech) to measure the adhesive layer The surface resistivity (Ω/□).

<Peeling Static Voltage>

When the measurement sample obtained above is peeled 180° at a tensile speed of 30m/min, use high-precision electrostatic sensors SK-035, SK-200 (Keyence Co., Ltd. has Co., Ltd.), the voltage (electrostatic voltage) generated by the electrification of the polarizing plate with AG treatment applied to the surface was measured, and the maximum value of the measured value was calculated as the peeling electrostatic voltage (kV).

<Shear retention force to polarizer>

On the polarizing plate with AG treatment applied to the surface, a surface protective film cut to a size of 25 mm wide x 35 mm long (the thickness of the adhesive layer is 20 μm) is 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 displacement (mm) of the surface protective film after being left for 24 hours was measured.

<Reoperability>

After drawing on the surface protective film of the measurement sample obtained above with a ballpoint pen (load of 500 g, 3 rounds), the surface protective film was peeled from the polarizing plate, 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 is: the case where no contamination transfers to the polarizer is evaluated as "○", the case where contamination transfer is confirmed on at least part of the trace drawn by the ballpoint pen is evaluated as "△", and the contamination is confirmed along the trace drawn by the ballpoint pen It was evaluated as "×" when it transferred and confirmed that the adhesive was detached from the surface of the adhesive.

<Durability>

Place the measurement sample obtained above in an environment of 60°C and 90% RH for 250 hours, then take it out and place it at room temperature. After further leaving it for 12 hours, measure the adhesive strength and confirm that there is no significant increase in the initial adhesive strength. . The evaluation target standard is: the case where the adhesive force after the test is 1.5 times or less of the initial adhesive force is evaluated as "○", and the case where the adhesive force exceeds 1.5 times is evaluated as "×".

The evaluation results are shown in Table 5. In addition, the surface resistivity is expressed as "m×10 ⁺ⁿ " in the form of "mE+n" (where m is an arbitrary real value, and n is a positive integer).

In addition, the displacement described in Table 5 shows the measured value of the displacement (mm) of the surface protective film in the shear retention test with respect to the polarizing plate.

Relative to the polarizer of the adherend, the surface protective film of Examples 1-8 has an adhesive force of 0.04~0.2N/25mm at a low-speed peeling speed of 0.3m/min, and an adhesive force of 2.0 at a high-speed peeling speed of 30m/min. N/25mm or less, the surface resistivity is 9.0×10 ⁺¹¹ Ω/□ or less, the peel static voltage is ±0~0.5kV, the load is 500g, and there is no dislocation in the shear retention test after 24 hours at 23℃. 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 the following performance requirements are met at the same time: (1) Even if the adhesive force is small, the opposite The adhesion force of the vibrator is also good; (2) durability, (3) reworkability, and (4) excellent antistatic performance.

The surface protective film of Comparative Example 1 may be due to (C) too many copolymerizable monomers containing carboxyl groups, and the acrylic polymer does not contain (D) polyalkylene glycol mono(meth)acrylate monomer, adhesive composition It does not contain (F) polyether-modified silicone compounds with HLB values of 7-12, (G) trifunctional isocyanate compounds are too few, and (J) antistatic agent is not included, so the low-speed peeling speed is 0.3m/min. The high-speed peeling speed of 30m/min has too much adhesive force, high surface resistivity and peeling static voltage, dislocation in the shear retention test, and poor operability and durability.

The surface protective film of Comparative Example 2 may be due to (C) too few copolymerizable monomers containing carboxyl groups, (D) polyalkylene glycol mono(meth)acrylate monomers with many diester components and high water content. The water solubility is low, and the HLB value of (F) polyether-modified silicone compound is too large. Therefore, the adhesion force at the low-speed peeling speed of 0.3m/min and the high-speed peeling speed of 30m/min is too large, the surface resistivity and peeling static The voltage is high, there is dislocation 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) hydroxyl-containing copolymerizable monomers, (C) excessive carboxyl-containing copolymerizable monomers, and (D) polyalkylene glycol mono(methyl) ) Acrylic monomer has many diester components, high water content, low solubility in water, so the gel fraction is low, and the adhesion is very large at low-speed peeling speed of 0.3m/min and high-speed peeling speed of 30m/min , Even if the surface resistivity is low, the peeling static voltage is high, and the reworkability is poor.

In the surface protective film of Comparative Example 4, (F) the HLB value of the polyether-modified silicone compound was too large, and there was a dislocation in the shear retention test.

In this way, in the surface protection films of Comparative Examples 1 to 4, it is not possible to simultaneously Meet all the following performance requirements: (1) Even if the adhesive force is small, the adhesion to the polarizer is good; (2) Durability, (3) Reoperability, and (4) Excellent antistatic performance.

Real industry utilization

The surface protective film for polarizers of the present invention solves the following problems in the prior art. If the adhesive force of the adhesive layer is reduced and the surface protective film is easily peeled from the adherend, the polarization of the surface protective film will be reduced. The adhesion force of the film is reduced. Therefore, as the size of the liquid crystal display increases, when the size of the polarizer is increased compared with the past, the problem of peeling of the protective film on the end surface of the polarizer, so it is industrially The use value is great.

Claims (8)

A surface protective film for polarizers, which is a surface protective film for polarizers with an adhesive layer formed on one side of a resin film. The adhesive layer is composed of an adhesive containing acrylic polymer, crosslinking agent, and antistatic agent. The composition is cross-linked, and the surface protective film for polarizers is characterized in that the acrylic polymer is composed of: (A) at least one of the (meth)acrylate monomers having C4-C18 alkyl groups A total of 100 parts by weight of more than one kind, (B) a total of 2-10 parts by weight of at least one of the copolymerizable monomers containing hydroxyl groups, (C) a total of at least one of the copolymerizable monomers containing carboxyl groups The amount is 0.05 to 0.3 parts by weight, (D) the total amount of at least one of the polyalkylene glycol mono(meth)acrylate monomers is 3 to 40 parts by weight, and (E) a nitrogen-containing vinyl group without a hydroxyl group The total amount of at least one of the monomers or alkoxy-containing alkyl (meth)acrylate monomers is 0.1-20 parts by weight, and the copolymer is composed of copolymers. The crosslinking agent is a trifunctional isocyanate compound , With respect to 100 parts by weight of the total amount of at least one or more of the (meth)acrylate monomers having C4 to C18 carbon atoms in the alkyl group (A), the adhesive composition contains the crosslinking agent 0.1~ 6 parts by weight, and 0.01 to 5.0 parts by weight of the antistatic agent, and further containing (F) at least one or more of polyether-modified silicone compounds having an HLB value of 7 to 12 in a total amount of 0.001 to 0.5 parts by weight , Laminated and cut into a width of 25mm×length of 35mm The surface protective film for polarizing plate of this size is applied with a load of 500g and left for 24 hours in an environment at a temperature of 23°C. There is no dislocation in the shear retention test of the polarizing plate. The (D) polyalkylene The glycol mono(meth)acrylate monomer is the average repeating number of the alkyleneoxy group constituting the polyalkylene glycol chain is 3-14, the diester component in the monomer is 0.2% or less, and the water content is 0.1 % Or less, and the solubility in water is a haze value of 2% or less in the state of a 20% aqueous solution. The surface protective film for polarizers as described in the first item of the scope of patent application, wherein the (D) polyalkylene glycol mono(meth)acrylate monomer is selected from the group consisting of polyalkylene glycol mono(methyl) ) At least one or more of the compound group consisting of acrylate, methoxy polyalkylene glycol (meth)acrylate, and ethoxy polyalkylene glycol (meth)acrylate. The surface protective film for polarizers as described in item 1 or 2 of the scope of patent application, wherein the (B) hydroxyl-containing copolymerizable monomer is selected from 8-hydroxyoctyl (meth)acrylate and 6-hydroxyhexyl (Meth)acrylate, 4-hydroxybutyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl(methyl) ) At least one compound from the group consisting of acrylamide and N-hydroxyethyl (meth)acrylamide, the (C) carboxyl-containing copolymerizable monomer is selected from (meth)acrylic acid, carboxyl group Ethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloxyethylhexahydrophthalic acid, 2-(meth)acryloxypropyl Hexahydrophthalic acid, 2-(meth)acryloxyethyl phthalic acid, 2-(meth)acryloxyethyl succinic acid, 2-(meth)acryloxyethyl Maleic acid, carboxyl polycaprolactone mono(meth)acrylate, 2-(meth)acrylic acid At least one or more of the compound group consisting of oxyethyltetrahydrophthalic acid. The surface protective film for polarizers as described in item 1 or 2 of the scope of patent application, wherein the trifunctional isocyanate compound is an isocyanurate body selected from hexamethylene diisocyanate compounds, isophorone diisocyanate Compound isocyanurate body, adduct of hexamethylene diisocyanate compound, adduct of isophorone diisocyanate compound, biuret of hexamethylene diisocyanate compound, isophorone Biuret of diisocyanate compound, isocyanurate of toluene diisocyanate compound, isocyanurate of xylylene diisocyanate compound, isocyanurate of hydrogenated xylylene diisocyanate compound At least one or more of the compound group consisting of an acid ester body, an adduct of a toluene diisocyanate compound, an adduct of a xylylene diisocyanate compound, and an adduct of a hydrogenated xylylene diisocyanate compound . The surface protective film for polarizers as described in item 1 or 2 of the scope of patent application, wherein the antistatic agent is an ionic compound with a melting point of 25-50°C and a solid at 25°C. The surface protective film for polarizers as described in item 1 or 2 of the scope of patent application, wherein for polarizers, the adhesive layer has an adhesive force of 0.04~0.2N/25mm at a low-speed peeling speed of 0.3m/min. The adhesive force at a peeling speed of 30m/min is 2.0N/25mm or less. The surface protective film for polarizers described in item 1 or 2 of the scope of patent application, wherein the surface resistivity of the adhesive layer is 9.0×10 ⁺¹¹ Ω/□ or less, and the peeling static voltage is ±0~0.5kV. The surface protective film for a polarizer as described in the first or second item of the scope of patent application, wherein the resin film has an antistatic treatment and an antifouling treatment on the side opposite to the side where the adhesive layer is formed on one side of the resin film.