JP7429751B2 - Antistatic surface protection film and optical film - Google Patents

Description

The present invention relates to an antistatic surface protection film that is bonded to the surface of optical components (hereinafter sometimes referred to as optical films) such as polarizing plates, retardation plates, and lens films for displays. More specifically, the present invention provides an antistatic surface protection film that causes less contamination of adherends, does not deteriorate over time, and has excellent peeling antistatic properties.

When manufacturing and transporting optical films such as polarizing plates, retardation plates, lens films for displays, anti-reflection films, hard coat films, transparent conductive films for touch panels, and optical products such as displays using them. In this method, a surface protection film is laminated on the surface of the optical film to prevent the surface from being stained or scratched in subsequent steps. Visual inspection of the optical film product is sometimes carried out with the surface protection film still attached to the optical film in order to improve work efficiency by eliminating the need to peel off the surface protection film and reattach it.
BACKGROUND ART Conventionally, a surface protection film in which an adhesive layer is provided on one side of a base film has been generally used in order to prevent scratches and dirt from adhering in the manufacturing process of optical products. The surface protection film is bonded to the optical film via a slightly adhesive adhesive layer. The reason why the adhesive layer has a low adhesive strength is that when the used surface protection film is peeled off from the surface of the optical film, it can be easily peeled off, and the adhesive has a low adhesive strength. This is to prevent the adhesive from adhering to and remaining on the optical film (preventing so-called adhesive residue from occurring).

In recent years, in the production process of liquid crystal display panels, the display screen of the liquid crystal display panel is controlled by the peeling voltage generated when the surface protection film laminated on the optical film is peeled off and removed. Phenomena of destruction of circuit components such as driver ICs and phenomena of damage to the alignment of liquid crystal molecules have occurred, although the number of occurrences is small.
Further, in order to reduce the power consumption of liquid crystal display panels, the driving voltage of liquid crystal materials has been lowered, and the breakdown voltage of driver ICs has also been lowered accordingly. Recently, there has been a demand for the peeling voltage to be within the range of +0.7 kV to -0.7 kV.
For this reason, in order to prevent problems caused by high peeling voltage when the surface protection film is peeled off from the optical film that is the adherend, an adhesive layer containing an antistatic agent is used to keep the peeling voltage low. A surface protection film using .

For example, Patent Document 1 discloses a surface protection film using an adhesive consisting of an alkyltrimethylammonium salt, a hydroxyl group-containing acrylic polymer, and a polyisocyanate.
Further, Patent Document 2 discloses an adhesive composition comprising an ionic liquid and an acrylic polymer having an acid value of 1.0 or less, and adhesive sheets using the same.
Further, Patent Document 3 discloses an adhesive composition comprising an acrylic polymer, a polyether polyol compound, and an alkali metal salt treated with an anion-adsorbing compound, and a surface protection film using the same.
Further, Patent Document 4 discloses an adhesive composition comprising an ionic liquid, an alkali metal salt, and a polymer having a glass transition temperature of 0° C. or lower, and a surface protection film using the same.
Further, Patent Documents 5 and 6 disclose that polyether-modified silicone is mixed into the adhesive layer of the surface protection film.

Japanese Patent Application Publication No. 2005-131957 Japanese Patent Application Publication No. 2005-330464 Japanese Patent Application Publication No. 2005-314476 Japanese Patent Application Publication No. 2006-152235 JP2009-275128A Patent No. 4537450

In Patent Documents 1 to 4 mentioned above, an antistatic agent is added inside the adhesive layer, but as the thickness of the adhesive layer increases and as time elapses, the bonding of the surface protection film becomes more difficult. The amount of antistatic agent transferred from the adhesive layer to the adherend is larger than that of the adherend. In addition, in optical films such as LR (Low Reflective) polarizing plates and AG (Anti Glare)-LR polarizing plates, the surface of the optical film is treated with anti-staining agents such as silicone compounds and fluorine compounds. When a surface protection film used for an optical film is peeled off from an optical film as an adherend, the peeling voltage becomes high.

Further, when polyether-modified silicone is mixed into the adhesive layer as described in Patent Documents 5 and 6, it is difficult to finely adjust the adhesive force of the surface protection film. In addition, since polyether-modified silicone is mixed in the adhesive layer, if the conditions for coating and drying the adhesive composition on the base film change, the adhesive layer on which the surface protection film has been formed may be damaged. Surface characteristics change slightly. Furthermore, from the viewpoint of protecting the surface of the optical film, the thickness of the adhesive layer cannot be made extremely thin. Therefore, it is necessary to increase the amount of polyether-modified silicone mixed into the adhesive layer depending on the thickness of the adhesive layer.As a result, the surface of the adherend is more likely to be contaminated, and the adhesive strength deteriorates over time. The contamination of the adherend changes.

In recent years, with the spread of 3D displays (stereoscopic displays), some optical films such as polarizing plates have an FPR (Film Patterned Retarder) film bonded to the surface thereof. After peeling off the surface protection film bonded to the surface of an optical film such as a polarizing plate, an FPR film is bonded. However, if the surface of an optical film such as a polarizing plate is contaminated with the adhesive or antistatic agent used in the surface protection film, there is a problem in that the FPR film is difficult to adhere to. Therefore, the surface protection film used for this purpose is required to have less contamination to the adherend.

On the other hand, some LCD panel manufacturers use a method to evaluate the contamination of the surface protection film on the adherend by peeling off the surface protection film attached to an optical film such as a polarizing plate and removing air bubbles. A method is adopted in which the adherend is re-attached and heat-treated under predetermined conditions, and then the surface protection film is peeled off and the surface of the adherend is observed. In this evaluation method, even if there is only a small amount of surface contamination on the adherend, the difference in the surface contamination of the adherend can be determined between the part where air bubbles were mixed and the part where the adhesive of the surface protection film was in contact. If there is, it will remain as a trace of air bubbles (sometimes called air bubble stain). Therefore, it is a very strict evaluation method for evaluating the contamination of the surface of the adherend. In recent years, there has been a demand for surface protection films that do not cause problems in contaminating the surface of adherends even when judged by such strict evaluation methods. However, it has been difficult to solve this problem with conventionally proposed surface protection films using adhesive layers containing antistatic agents.

For this reason, there is a need for a surface protection film for use in optical films that causes very little contamination of adherends and that does not change over time in its contamination of adherends. Furthermore, there is a need for a surface protection film that has a low peeling voltage when peeled from an adherend.

The present inventors have conducted extensive studies to solve this problem.
In order to reduce contamination of the adherend and to reduce changes in antistatic performance over time, it is necessary to reduce the amount of antistatic agent added, which is presumed to be the cause of contaminating the adherend. However, if the amount of antistatic agent added is reduced, the peeling voltage when the surface protection film is peeled off from the adherend becomes high. The present inventors studied a method of suppressing the peeling electrostatic voltage when peeling a surface protection film from an adherend without increasing the absolute amount of the antistatic agent added. As a result, instead of adding and mixing an antistatic agent into the adhesive composition to form an adhesive layer, the adhesive composition was coated and dried to form the adhesive layer, and then the adhesive layer was laminated. It has been discovered that by adding an appropriate amount of antistatic agent to the surface of the layer, the peeling voltage when peeling the surface protection film from the optical film that is the adherend can be kept low, and the present invention completed.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide an antistatic surface protection film that causes less contamination of adherends, does not deteriorate over time, and has excellent antistatic properties when peeled off. shall be.

In order to solve the above problems, the antistatic surface protection film of the present invention is produced by coating and drying an adhesive composition to laminate an adhesive layer, and then applying an appropriate amount of liquid at 20°C to the surface of the adhesive layer. Our technical philosophy is to suppress the contamination of the adherend by applying silicone compounds and antistatic agents, and to also suppress the peeling electrostatic voltage when peeling from the optical film, which is the adherend. There is.

In order to solve the above problems, the present invention makes it possible to transfer an antistatic agent only to the surface of the adhesive layer of an antistatic surface protection film in which an adhesive layer is formed on one side of a base film. A release film for an antistatic surface protection film, wherein the adhesive layer is formed by crosslinking an adhesive composition containing an acrylic polymer and a crosslinking agent, and the acrylic polymer is (A ) A group of monomers copolymerizable with at least one (meth)acrylic acid ester monomer whose alkyl group has a carbon number of C4 to C18, (B) a copolymerizable monomer containing a hydroxyl group, (C) A copolymerizable monomer containing a carboxyl group, (D) a polyalkylene glycol mono(meth)acrylate monomer, and (E) a nitrogen-containing vinyl monomer that does not contain a hydroxyl group or an alkyl (meth) containing alkoxy group that does not contain a hydroxyl group. ) an acrylate monomer and at least one selected from the copolymerizable monomer group consisting of A release film for an antistatic surface protection film is formed by laminating a release agent layer containing an antistatic agent on one side of a resin film, and the release agent layer contains a release agent containing dimethylpolysiloxane as a main component, and a release agent layer containing an antistatic agent is laminated on one side of a resin film. The liquid silicone compound is formed from a resin composition containing polyether-modified silicone and the antistatic agent, and is based on 100 parts by weight of the solid content of the release agent containing dimethylpolysiloxane as the main component. , containing the polyether-modified silicone and the antistatic agent in a solid content of 5 to 100 parts by weight, and the release film for an antistatic surface protection film is applied to the adhesive layer via the release agent layer. A release film for an antistatic surface protection film, characterized in that the silicone compound and the antistatic agent of the release agent layer can be transferred only to the surface of the adhesive layer when bonded to the surface of the adhesive layer. I will provide a.

In addition, the copolymerizable monomer containing a hydroxyl group (B) is 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, ) acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and N-hydroxyethyl(meth)acrylamide.

In addition, the copolymerizable monomer containing a carboxyl group (C) is (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethylhexahydrophthal Acid, 2-(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethylmaleic acid It is preferably at least one selected from the group of compounds consisting of acid, carboxypolycaprolactone mono(meth)acrylate, and 2-(meth)acryloyloxyethyltetrahydrophthalic acid.

Further, the polyalkylene glycol mono(meth)acrylate monomer (D) is selected from polyalkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, and ethoxypolyalkylene glycol (meth)acrylate. In addition, it is preferable that at least one kind is used.

Further, it is preferable that the acrylic polymer contains at least one of the above (E) a nitrogen-containing vinyl monomer that does not contain a hydroxyl group or an alkyl (meth)acrylate monomer containing an alkoxy group as the copolymerizable monomer group.

In addition, as the above-mentioned (F) bifunctional or higher isocyanate compound, the bifunctional isocyanate compound is an acyclic aliphatic isocyanate compound, which is a compound produced by reacting a diisocyanate compound and a diol compound, and as a diisocyanate compound. is an aliphatic diisocyanate, and is one selected from the compound group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate, and the diol compound is 2-methyl-1 , 3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 3 - A trifunctional isocyanate compound consisting of one type selected from the group of compounds consisting of methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxypivalate, polyethylene glycol, and polypropylene glycol. Examples include an isocyanurate of a hexamethylene diisocyanate compound, an isocyanurate of an isophorone diisocyanate compound, an adduct of a hexamethylene diisocyanate compound, an adduct of an isophorone diisocyanate compound, a bullet of a hexamethylene diisocyanate compound, a bullet of an isophorone diisocyanate compound, Isocyanurate of tolylene diisocyanate compound, isocyanurate of xylylene diisocyanate compound, isocyanurate of hydrogenated xylylene diisocyanate compound, adduct of tolylene diisocyanate compound, adduct of xylylene diisocyanate compound, hydrogenated xylylene diisocyanate Preferably, it consists of an adduct of the compound.

Further, it is preferable that the pressure-sensitive adhesive composition contains (I) a polyether-modified siloxane compound having an HLB value of 7 to 15.

Moreover, it is preferable that the silicone compound in the release agent layer is polyether-modified silicone.

Further, it is preferable that the antistatic agent in the release agent layer is an alkali metal salt.

Furthermore, in order to solve the above-mentioned problems, the present invention provides that (A) a (meth)acrylic acid ester monomer in which the alkyl group has a carbon number of C4 to C18 is added to one side of a base film made of a transparent resin. (B) a copolymerizable monomer containing a hydroxyl group, (C) a copolymerizable monomer containing a carboxyl group, and (D) a polyalkylene glycol mono(meth) ) acrylic acid ester monomer, and (E) at least one selected from the copolymerizable monomer group consisting of a nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth)acrylate monomer that does not contain a hydroxyl group. An adhesive layer made of an acrylic copolymer and a release film in which a release agent layer containing an antistatic agent is laminated on one side of a resin film, such that the adhesive layer and the release agent layer are in contact with each other. , the release agent layer is formed of a resin composition containing a release agent containing dimethylpolysiloxane as a main component, a silicone compound that is liquid at 20° C., and an antistatic agent, The present invention provides an antistatic surface protection film, characterized in that the adhesive layer has a peel voltage of ±0.6 kV or less.

Further, it is preferable that the silicone compound in the release agent layer is polyether-modified silicone.

Further, it is preferable that the antistatic agent in the release agent layer is an alkali metal salt.

Further, the present invention provides an optical film formed by laminating the above-mentioned antistatic surface protection film.

The present invention also provides an optical component in which the above antistatic surface protection film is laminated.

The antistatic surface protection film of the present invention causes less contamination of adherends, and the low contamination property of adherends does not change over time. Further, according to the present invention, even if the surface of the adherend is an optical film, such as an LR polarizing plate or an AG-LR polarizing plate, which has been treated with anti-fouling treatment with a silicone compound or a fluorine compound, antistatic The peel-off voltage generated when the surface protection film is peeled off from the adherend can be suppressed to a low level, and an antistatic surface-protection film that does not deteriorate over time and has excellent peel-off antistatic performance can be provided.
According to the antistatic surface protection film of the present invention, since the surface of an optical film can be reliably protected, productivity and yield can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing the concept of an antistatic surface protection film of the present invention. FIG. 2 is a cross-sectional view showing a state in which a release film is peeled off from the antistatic surface protection film of the present invention. FIG. 1 is a sectional view showing one embodiment of the optical component of the present invention.

Hereinafter, the present invention will be described in detail based on embodiments.
FIG. 1 is a cross-sectional view showing the concept of the antistatic surface protection film of the present invention. In this antistatic surface protection film 10, an adhesive layer 2 is formed on one surface of a transparent base film 1. A release film 5 in which a release agent layer 4 is formed on the surface of a resin film 3 is bonded to the surface of the adhesive layer 2 .

As the base film 1 used in the antistatic surface protection film 10 according to the present invention, a base film made of a transparent and flexible resin is used. Thereby, the appearance of the optical component can be inspected while the antistatic surface protection film is bonded to the optical component as the adherend. The film made of a transparent resin used as the base film 1 is preferably a polyester film such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, or polybutylene terephthalate. In addition to polyester films, films made of other resins can also be used as long as they have the necessary strength and optical suitability. The base film 1 may be an unstretched film or a uniaxially or biaxially stretched film. Furthermore, the stretching ratio of the stretched film and the orientation angle of the axis formed as the stretched film crystallizes may be controlled to specific values.
The thickness of the base film 1 used in the antistatic surface protection film 10 according to the present invention is not particularly limited, but preferably has a thickness of about 12 to 100 μm, and is easy to handle if it has a thickness of about 20 to 50 μm. , more preferred.
If necessary, an antifouling layer to prevent surface stains, an antistatic layer, a hard coat layer to prevent scratches, etc. are applied to the surface of the base film 1 opposite to the surface on which the adhesive layer 2 is formed. can be provided. Further, the surface of the base film 1 may be subjected to adhesion-facilitating treatment such as surface modification by corona discharge or application of an anchor coating agent.

The adhesive layer 2 used in the antistatic surface protection film 10 according to the present invention is an adhesive that adheres to the surface of the adherend, can be easily peeled off after use, and does not easily contaminate the adherend. Although there are no particular limitations, it is common to use an acrylic adhesive made by crosslinking a (meth)acrylate copolymer in consideration of durability after lamination to an optical film. .

In particular, the main ingredient of the acrylic adhesive contains (B) a hydroxyl group as a monomer group copolymerizable with at least one (A) (meth)acrylic acid ester monomer whose alkyl group has carbon atoms of C4 to C18. (C) a copolymerizable monomer containing a carboxyl group, (D) a polyalkylene glycol mono(meth)acrylate monomer, and (E) a nitrogen-containing vinyl monomer that does not contain a hydroxyl group. Alternatively, an adhesive layer made of an acrylic polymer, which is a copolymer containing an alkoxy group-containing alkyl (meth)acrylate monomer and at least one selected from the group of copolymerizable monomers consisting of the following, is preferable.
Furthermore, in addition to the acrylic polymer, an adhesive composition comprising an adhesive composition containing (F) an isocyanate compound having two or more functionalities, (G) a crosslinking accelerator, and (H) a ketoenol tautomer compound. An agent layer is preferred.

(A) Examples of (meth)acrylic acid ester monomers in which the alkyl group has carbon atoms of C4 to C18 include butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl ( meth)acrylate, octyl(meth)acrylate, isooctyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, nonyl(meth)acrylate, isononyl(meth)acrylate, decyl(meth)acrylate, isodecyl(meth)acrylate, 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 Acrylate, isomyristyl (meth)acrylate, cetyl (meth)acrylate, isocetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, and the like.
When the total amount of acrylic polymer in the copolymer is 100 parts by weight, (A) contains a (meth)acrylic acid ester monomer whose alkyl group has carbon atoms of C4 to C18 in a proportion of 50 to 95 parts by weight. Preferably.

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

(C) The copolymerizable monomer containing a carboxyl group is (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2 -(meth)acryloyloxypropylhexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethylmaleic acid, carboxy It is preferably at least one selected from the group of compounds consisting of polycaprolactone mono(meth)acrylate and 2-(meth)acryloyloxyethyltetrahydrophthalic acid.
When the total amount of acrylic polymer in the copolymer is 100 parts by weight, it is preferable that the above-mentioned (C) carboxyl group-containing copolymerizable monomer is contained in a proportion of 0 to 1.0 parts by weight. In the adhesive layer according to the present invention, the adhesive composition does not need to contain (C) a copolymerizable monomer containing a carboxyl group.

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

(D) The polyalkylene glycol mono(meth)acrylate monomer is selected from polyalkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol(meth)acrylate, and ethoxypolyalkylene glycol(meth)acrylate. It is preferable that at least one kind is used.
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-poly Butylene glycol-mono(meth)acrylate, polypropylene glycol-polybutylene glycol-mono(meth)acrylate, polyethylene glycol-polypropylene glycol-polybutylene glycol-mono(meth)acrylate; methoxypolyethylene glycol-(meth)acrylate, methoxypolypropylene glycol -(meth)acrylate, methoxypolybutylene glycol-(meth)acrylate, methoxy-polyethylene glycol-polypropylene glycol-(meth)acrylate, methoxy-polyethylene glycol-polybutylene glycol-(meth)acrylate, methoxy-polypropylene glycol-polybutylene Glycol-(meth)acrylate, Methoxy-polyethylene glycol-polypropylene glycol-polybutylene glycol-(meth)acrylate; Ethoxypolyethylene glycol-(meth)acrylate, Ethoxypolypropylene glycol-(meth)acrylate, Ethoxypolybutylene glycol-(meth) Acrylate, Ethoxy-polyethylene glycol-polypropylene glycol-(meth)acrylate, Ethoxy-polyethylene glycol-polybutylene glycol-(meth)acrylate, Ethoxy-polypropylene glycol-polybutylene glycol-(meth)acrylate, Ethoxy-polyethylene glycol-polypropylene glycol -Polybutylene glycol-(meth)acrylate, etc.
When the total amount of acrylic polymer in the copolymer is 100 parts by weight, it is preferable that the polyalkylene glycol mono(meth)acrylic acid ester monomer (D) is contained in a proportion of 0 to 50 parts by weight. In the adhesive layer according to the present invention, the adhesive composition does not need to contain the (D) polyalkylene glycol mono(meth)acrylate monomer.

It is preferable that the acrylic polymer contains at least one of (E) a nitrogen-containing vinyl monomer that does not contain a hydroxyl group or an alkyl (meth)acrylate monomer containing an alkoxy group, as the copolymerizable monomer group.

Among (E), (E-1) nitrogen-containing vinyl monomers include vinyl monomers containing an amide bond, vinyl monomers containing an amino group, vinyl monomers having a nitrogen-containing heterocyclic structure, and the like. More specifically, N-vinyl-2-pyrrolidone, N-vinylpyrrolidone, methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinyl Cyclic nitrogen vinyl compounds having an N-vinyl-substituted heterocyclic structure, such as pyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, and N-vinyllaurylolactam; N-( meth)acryloylmorpholine, N-(meth)acryloylpiperazine, N-(meth)acryloylaziridine, N-(meth)acryloylazetidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylpiperidine, N-(meth)acryloylpiperidine, ) Cyclic nitrogen vinyl compounds having an N-(meth)acryloyl-substituted heterocyclic structure, such as acryloylazepane and N-(meth)acryloylazocane; nitrogen atoms and Cyclic nitrogen vinyl compounds having a heterocyclic structure having an ethylenically unsaturated bond in the ring; (meth)acrylamide, N-methyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-t-butyl (meth)acrylamide Unsubstituted or monoalkyl-substituted (meth)acrylamide such as acrylamide; N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropylacrylamide, N,N-diisopropyl(meth)acrylamide ) acrylamide, N,N-dibutyl (meth)acrylamide, N-ethyl-N-methyl (meth)acrylamide, N-methyl-N-propyl (meth)acrylamide, N-methyl-N-isopropyl (meth)acrylamide, etc. Dialkyl-substituted (meth)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-diethylaminomethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N-ethyl-N-methylaminoethyl (meth)acrylate, ) acrylate, N-methyl-N-propylaminoethyl (meth)acrylate, N-methyl-N-isopropylaminoethyl (meth)acrylate, N,N-dibutylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate, ) Acrylate and other dialkylamino (meth)acrylates; N,N-dimethylaminopropyl (meth)acrylamide, N,N-diethylaminopropyl (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 (meth)acrylamide N,N-dialkyl-substituted aminopropyl (meth)acrylamide such as; N-vinylcarboxylic acid amides such as N-vinylformamide, N-vinylacetamide, N-vinyl-N-methylacetamide; N-methoxymethyl (meth) (Meth)acrylamides such as acrylamide, N-ethoxyethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, diacetone acrylamide, N,N-methylenebis(meth)acrylamide; unsaturation such as (meth)acrylonitrile Examples include carboxylic acid nitriles; and the like.

(E-1) As the nitrogen-containing vinyl monomer, one that does not contain a hydroxyl group is preferable, and one that does not contain a hydroxyl group or a carboxyl group is more preferable. Examples of such monomers include the monomers listed above, such as acrylic monomers containing N,N-dialkyl-substituted amino groups and N,N-dialkyl-substituted amide groups; N-vinyl-2-pyrrolidone, N-vinyl N-vinyl-substituted lactams such as caprolactam and N-vinyl-2-piperidone; N-(meth)acryloyl-substituted cyclic amines such as N-(meth)acryloylmorpholine and N-(meth)acryloylpyrrolidine are preferred.

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

When the total amount of acrylic polymer in the copolymer is 100 parts by weight, 0 to 20 parts by weight of (E-1) a nitrogen-containing vinyl monomer that does not contain a hydroxyl group or (E-2) an alkyl (meth)acrylate monomer containing an alkoxy group. It is preferable that the content be in the proportion of 50%. (E-1) A nitrogen-containing vinyl monomer that does not contain a hydroxyl group and (E-2) an alkyl (meth)acrylate monomer containing an alkoxy group may be used alone or in combination. In the adhesive layer according to the present invention, the adhesive composition does not need to contain (E) a nitrogen-containing vinyl monomer that does not contain a hydroxyl group or an alkyl (meth)acrylate monomer that contains an alkoxy group.

(F) The isocyanate compound having two or more functionalities may be at least one kind or two or more kinds selected from polyisocyanate compounds having at least two or more isocyanate (NCO) groups in one molecule. Polyisocyanate compounds are classified into aliphatic isocyanates, aromatic isocyanates, acyclic isocyanates, alicyclic isocyanates, and any of them may be used. Specific examples of polyisocyanate compounds include aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), diphenylmethane diisocyanate (MDI), and xylylene diisocyanate (XDI). , hydrogenated xylylene diisocyanate (H6XDI), dimethyldiphenylene diisocyanate (TOID), and tolylene diisocyanate (TDI).
Examples of trifunctional or higher-functional isocyanate compounds include biuret-modified and isocyanurate-modified derivatives of bifunctional isocyanate compounds (compounds having two NCO groups in one molecule), and tri- or higher-functional isocyanate compounds such as trimethylolpropane (TMP) and glycerin. Examples include adducts (modified polyols) with polyols (compounds having at least three or more OH groups in one molecule).
(F) It is also possible to use only a trifunctional isocyanate compound (F-1) or only a difunctional isocyanate compound (F-2) as the bifunctional or higher functional isocyanate compound. It is also possible to use (F-1) the trifunctional isocyanate compound and (F-2) the difunctional isocyanate compound together.

Furthermore, the trifunctional isocyanate compound (F-1) used in the present invention includes an isocyanurate of a hexamethylene diisocyanate compound, an isocyanurate of an isophorone diisocyanate compound, an adduct of a hexamethylene diisocyanate compound, an adduct of an isophorone diisocyanate compound, (F-1-1) At least one selected from the first aliphatic isocyanate compound group consisting of a burette of a hexamethylene diisocyanate compound and a buret of an isophorone diisocyanate compound, and a tolylene diisocyanate compound. isocyanurate of xylylene diisocyanate compound, isocyanurate of hydrogenated xylylene diisocyanate compound, adduct of tolylene diisocyanate compound, adduct of xylylene diisocyanate compound, adduct of hydrogenated xylylene diisocyanate compound It is preferable to include at least one selected from the group of (F-1-2) second aromatic isocyanate compounds consisting of (F-1-2). It is preferable to use (F-1-1) the first aliphatic isocyanate compound group and (F-1-2) the second aromatic isocyanate compound group together. In the present invention, as (F-1) the trifunctional isocyanate compound, (F-1-1) at least one selected from the first aliphatic isocyanate compound group; and (F-1-2) ) By using in combination with at least one selected from the second group of aromatic isocyanate compounds, the balance of adhesive strength in the low-speed peeling region and the high-speed peeling region can be further improved.

Further, (F-1) the trifunctional isocyanate compound includes at least one kind selected from the first aliphatic isocyanate compound group (F-1-1) and the above (F-1-2). ) at least one selected from the second aromatic isocyanate compound group, and contains a total of 0.5 to 5.0 parts by weight based on 100 parts by weight of the copolymer. It is preferable that Further, (F-1-1) at least one selected from the first group of aliphatic isocyanate compounds, and (F-1-2) the second group of aromatic isocyanate compounds. The mixing ratio of (F-1-1):(F-1-2) with at least one selected from is within the range of 10%:90% to 90%:10% by weight. is preferred.

Furthermore, the (F-2) difunctional isocyanate compound used in the present invention is preferably an acyclic aliphatic isocyanate compound produced by reacting a diisocyanate compound and a diol compound.
For example, a diisocyanate compound with the general formula "O=C=N-X-N=C=O" (however, X is a divalent group) is formed with the general formula "HO-Y-OH" (however, Y is a divalent group) ) represents a diol compound, examples of the compound produced by reacting a diisocyanate compound and a diol compound include a compound represented by the following general formula Z.

[General formula Z]
O=C=N-X-(NH-CO-O-Y-O-CO-NH-X) _n -N=C=O

Here, n is an integer greater than or equal to 0. When n is 0, the general formula Z represents "O=C=N-X-N=C=O". The difunctional acyclic aliphatic isocyanate compound may include a compound where n is 0 in the general formula Z (a diisocyanate compound that has not reacted with the diol compound), but a compound where n is an integer of 1 or more is an essential component. It is preferable to include it as The bifunctional acyclic aliphatic isocyanate compound may be a mixture of a plurality of compounds in which n in the general formula Z is different.

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

The diol compound represented by the general formula "HO-Y-OH" is an aliphatic diol. Y is preferably an acyclic aliphatic divalent group. The diol compounds include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2 - from the group of compounds consisting of butyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxypivalate, polyethylene glycol, polypropylene glycol It is preferable to consist of one or more selected types.

The weight ratio (F-1/F-2) of the trifunctional isocyanate compound (F-1) to the difunctional isocyanate compound (F-2) is preferably 1 to 90. It is preferable that the amount of the difunctional or higher functional isocyanate compound (F) is 0.1 to 10 parts by weight based on 100 parts by weight of the acrylic polymer.

(G) The crosslinking accelerator for the metal chelate compound may be any substance that functions as a catalyst for the reaction (crosslinking reaction) between the copolymer and the crosslinking agent when a polyisocyanate compound is used as the crosslinking agent, Examples include amine compounds such as tertiary amines, metal chelate compounds, organometallic compounds such as organotin compounds, organolead compounds, and organozinc compounds. In the present invention, metal chelate compounds and organic tin compounds are preferred as the crosslinking promoter.

The metal chelate compound is a compound in which one or more polydentate ligands L are bonded to a 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 one metal atom M is represented by M(L) _m (X) _n , m≧1 and n≧0. When m is 2 or more, m L's may be the same ligand or may be different ligands. When n is 2 or more, the n pieces of X may be the same or different ligands.

Examples of the metal atoms M include Fe, Ni, Mn, Cr, V, Ti, Ru, Zn, Al, Zr, and Sn.
Examples of the polydentate ligand L include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate, acetylacetone (also known as 2,4-pentanedione), Examples include β-diketones such as 2,4-hexanedione and benzoylacetone. These are ketoenol tautomer compounds, and in the polydentate ligand L, the enol may be a deprotonated enolate (for example, acetylacetonate).
As the monodentate ligand and alkoxy groups such as a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, a butoxy group, and the like.

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

Examples of the organic tin compound include dialkyltin oxides, dialkyltin fatty acid salts, and stannous fatty acid salts. Conventionally, dibutyltin compounds have been widely used, but in recent years, the problem of toxicity of organotin compounds has been pointed out, and in particular, tributyltin (TBT) contained in dibutyltin compounds is also a concern as an endocrine disruptor. From the viewpoint of safety, long-chain alkyltin compounds such as dioctyltin compounds are preferred. Specific examples of organic tin compounds include dioctyltin oxide and dioctyltin dilaurate. Tentatively, Sn compounds can also be used, but in view of the trend of requiring the use of safer substances in the future, Al, Ti, Fe, etc., which are safer than Sn, will be used. Preferably, metal chelate compounds are used.
The metal chelate compound in the adhesive composition of the present invention is at least one selected from the group consisting of an aluminum chelate compound, a titanium chelate compound, an iron chelate compound, and a tin chelate compound (but not containing TBT). It is preferable that more than one species is included.
(G) The metal chelate compound crosslinking accelerator is preferably contained in an amount of 0.001 to 0.5 parts by weight per 100 parts by weight of the copolymer.

(H) Ketoenol tautomer compounds include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate, acetylacetone, and 2,4-hexanedione. and β-diketones such as benzoylacetone. In a pressure-sensitive adhesive composition using a polyisocyanate compound as a cross-linking agent, these compounds inhibit excessive viscosity increase and gelation of the pressure-sensitive adhesive composition after the cross-linking agent is blended by blocking the isocyanate groups of the cross-linking agent. , the pot life of the adhesive composition can be extended.
(H) The ketoenol tautomer compound is preferably contained in an amount of 0.1 to 200 parts by weight based on 100 parts by weight of the copolymer.

(H) The ketoenol tautomer compound has the effect of suppressing crosslinking, contrary to (G) the crosslinking promoter for the metal chelate compound. It is preferable to appropriately set the proportion of the ketoenol tautomer compound. In order to lengthen the pot life and improve storage stability of the adhesive composition, the weight ratio of (G):(H) is preferably in the range of 1:1 to 1:300, and more preferably, The ratio is 1:30 to 1:300, most preferably 1:80 to 1:300.

The adhesive composition can optionally contain (I) a polyether-modified siloxane compound. (I) The polyether-modified siloxane compound is a siloxane compound having a polyether group, and in addition to the usual siloxane unit [-SiR ¹ ₂ -O-], the polyether-modified siloxane compound [-SiR ¹ (R ² O(R ³ O) _n R ⁴ )-O-]. Here, R ¹ is one or more alkyl groups or aryl groups, R ² and R ³ are one or more alkylene groups, and R ⁴ is one or more alkyl groups or acyl groups. etc. (terminal group). Examples of the polyether group include polyoxyalkylene groups such as polyoxyethylene group [(C ₂ H ₄ O) _n ] and polyoxypropylene group [(C ₃ H ₆ O) _n ].

(I) The polyether-modified siloxane compound is preferably a polyether-modified siloxane compound having an HLB value of 7 to 15. Furthermore, it is preferable that the polyether-modified siloxane compound (I) is contained in an amount of 0.01 to 1.0 parts by weight per 100 parts by weight of the copolymer. More preferably, it is 0.1 to 0.5 parts by weight.
HLB is a hydrophilic-lipophilic balance (hydrophilic-lipophilic ratio) defined, for example, in JIS K3211 (surfactant term).

(I) 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 silicon hydride group by a hydrosilylation reaction. can. Specifically, dimethylsiloxane/methyl (polyoxyethylene) siloxane copolymer, dimethylsiloxane/methyl (polyoxyethylene) siloxane/methyl (polyoxypropylene) siloxane copolymer, dimethylsiloxane/methyl (polyoxypropylene) Examples include siloxane polymers.
(I) By blending the polyether-modified siloxane compound into the adhesive composition, the adhesive force and rework performance of the adhesive can be improved. If the adhesive composition does not contain a polyether-modified siloxane compound, the cost will be lower.

Furthermore, as other components, copolymerizable (meth)acrylic monomers containing alkylene oxide, (meth)acrylamide monomers, dialkyl-substituted acrylamide monomers, surfactants, curing accelerators, plasticizers, fillers, curing retarders, Known additives such as processing aids, anti-aging agents, and antioxidants can be appropriately blended. These may be used alone or in combination of two or more.

The main copolymer used in the adhesive composition of the present invention is a monomer group copolymerizable with (A) at least one (meth)acrylic acid ester monomer in which the alkyl group has a carbon number of C4 to C18. (B) a copolymerizable monomer containing a hydroxyl group, (C) a copolymerizable monomer containing a carboxyl group, (D) a polyalkylene glycol mono(meth)acrylate monomer, and (E) a copolymerizable monomer containing a hydroxyl group. It can be synthesized by copolymerizing a non-containing nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth)acrylate monomer with at least one selected from the group of copolymerizable monomers. The method of polymerizing the copolymer is not particularly limited, and any suitable polymerization method such as solution polymerization, emulsion polymerization, etc. can be used.
The pressure-sensitive adhesive composition of the present invention includes the above-mentioned copolymer, (F) a bifunctional or higher-functional isocyanate compound, (G) a crosslinking accelerator for a metal chelate compound, and (H) a ketoenol tautomer compound, and further optionally It can be prepared by adding any additives.

The copolymer is preferably an acrylic polymer, and preferably contains 50 to 100% by weight of an acrylic monomer such as a (meth)acrylic acid ester monomer, (meth)acrylic acid, or (meth)acrylamide.
Further, the acid value of the acrylic polymer is preferably 0.01 to 8.0. Thereby, it is possible to improve the staining property and improve the ability to prevent adhesive residue from occurring.
Here, the "acid value" is one of the indicators representing the acid content, and is expressed by the number of mg of potassium hydroxide required to neutralize 1 g of a polymer containing a carboxyl group.

The adhesive force of the adhesive layer formed by crosslinking the adhesive composition at a low peeling speed of 0.3 m/min is 0.05 to 0.1 N/25 mm, and at a high peeling speed of 30 m/min. It is preferable that the adhesive force is 1.0 N/25 mm or less. As a result, performance can be obtained in which the adhesive force does not change much depending on the peeling speed, and it becomes possible to peel off quickly even with high-speed peeling. Moreover, when the surface protection film is once removed for reattachment, excessive force is not required and it can be easily removed from the adherend.

It is preferable that the adhesive layer formed by crosslinking the adhesive composition has a surface resistivity of 5.0×10 ⁺¹² Ω/□ or less and a peel voltage of “±0.6 kV or less”. In the present invention, "±0.6 kV or less" means 0 to -0.6 kV and 0 to +0.6 kV, that is, -0.6 to +0.6 kV. If the surface resistivity is high, the ability to release static electricity generated by charging during peeling will be poor, so by reducing the surface resistivity sufficiently, peeling that occurs due to static electricity generated when the adhesive layer is peeled off from the adherend can be reduced. The electrostatic voltage is reduced, and it is possible to suppress the influence on the electrical control circuit of the adherend.

The gel fraction of the adhesive layer formed by crosslinking the adhesive composition of the present invention (crosslinked adhesive) is preferably 95 to 100%. Due to this high gel fraction, the adhesive strength does not become excessive even at low peeling speeds, and the elution of unpolymerized monomers or oligomers from the copolymer is reduced, improving reworkability and even at high temperatures and high humidity. Durability is improved and contamination of adherends can be suppressed.

The adhesive film of the present invention is formed by forming an adhesive layer formed by crosslinking the adhesive composition of the present invention on one or both sides of a resin film. Moreover, the surface protection film of the present invention is a surface protection film formed by forming a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition of the present invention on one side of a resin film. The adhesive composition of the present invention has the above-mentioned components (A) to (H) blended in a well-balanced manner, so it has excellent antistatic performance and has excellent antistatic performance at low and high peeling speeds. It has an excellent balance of adhesive strength, and is also excellent in durability and rework performance (no contamination transferred to the adherend after tracing the surface protection film through the adhesive layer with a ballpoint pen). Become. Therefore, it can be suitably used as a surface protection film for a polarizing plate.

The thickness of the adhesive layer 2 used in the antistatic surface protection film 10 according to the present invention is not particularly limited, but is preferably about 5 to 40 μm, more preferably about 10 to 30 μm. The adhesive layer 2 has a slight adhesive force with a peel strength (adhesive force) of about 0.03 to 0.3 N/25 mm to the surface of the adherend of the antistatic surface protection film. This is preferred because it provides excellent operability when peeling off the antistatic surface protection film. Further, since the operability when peeling the release film 5 from the antistatic surface protection film 10 is excellent, the peeling force of the release film 5 from the adhesive layer 2 is preferably 0.2 N/50 mm or less.

Furthermore, the release film 5 used in the antistatic surface protection film 10 according to the present invention includes a release agent containing dimethylpolysiloxane as a main component and a silicone compound that is liquid at 20° C. on one side of the resin film 3. A release agent layer 4 is formed using a resin composition containing an antistatic agent.

Examples of the resin film 3 include polyester film, polyamide film, polyethylene film, polypropylene film, polyimide film, etc., but polyester film is particularly preferred because it has excellent transparency and is relatively inexpensive. . The resin film may be an unstretched film or a uniaxially or biaxially stretched film. Furthermore, the stretching ratio of the stretched film and the orientation angle of the axis formed as the stretched film crystallizes may be controlled to specific values.
The thickness of the resin film 3 is not particularly limited, but for example, a thickness of about 12 to 100 μm is preferable, and a thickness of about 20 to 50 μm is more preferable because it is easy to handle.
Further, if necessary, the surface of the resin film 3 may be subjected to adhesion-facilitating treatment such as surface modification by corona discharge or application of an anchor coating agent.

The release agent containing dimethylpolysiloxane as a main component constituting the release agent layer 4 includes known silicone release agents such as addition reaction type, condensation reaction type, cationic polymerization type, and radical polymerization type. Products commercially available as addition-reactive silicone release agents include, for example, KS-776A, KS-847T, KS-779H, KS-837, KS-778, and KS-830 (manufactured by Shin-Etsu Chemical Co., Ltd.). , SRX-211, SRX-345, SRX-357, SD7333, SD7220, SD7223, LTC-300B, LTC-350G, LTC-310 (manufactured by Dow Corning Toray Industries, Inc.). Examples of commercially available condensation reaction type products include SRX-290 and SYLOFF-23 (manufactured by Dow Corning Toray Industries, Inc.). Examples of commercially available cationic polymerization products include TPR-6501, TPR-6500, UV9300, VU9315, UV9430 (manufactured by Momentive Performance Materials), and X62-7622 (manufactured by Shin-Etsu Chemical Co., Ltd.). ), etc. Examples of commercially available products of the radical polymerization type include X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.).

Examples of the silicone compound that is liquid at 20° C. that constitutes the release agent layer 4 include polyether-modified silicone, alkyl-modified silicone, and carbinol higher fatty acid ester-modified silicone. In the present invention, in order to improve the antistatic property of the surface of the adhesive layer, a silicone compound that is liquid at 20°C is used in a compatible state in a release agent layer mainly composed of dimethylpolysiloxane. It will be done. Among the modified silicone compounds, polyether-modified silicones are preferred for use in the present invention. The polyether chain in polyether-modified silicone is composed of ethylene oxide, propylene oxide, etc., and for example, by selecting the molecular weight of the polyethylene oxide used for the side chain, physical properties such as compatibility with silicone release agents and antistatic effect can be adjusted. is adjusted.
In addition, commercially available polyether-modified silicone products include, for example, KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-642 (manufactured by Shin-Etsu Chemical Co., Ltd.), SH8400, SH8700, SF8410 (manufactured by Dow Corning Toray), TSF-4440, TSF-4441, TSF-4445, TSF-4446, TSF-4450 (manufactured by Momentive Performance Materials), BYK-300, BYK -306, BYK-307, BYK-320, BYK-325, BYK-330 (manufactured by BYK Chemie).
The amount of a silicone compound that is liquid at 20°C to a release agent containing dimethylpolysiloxane as a main component varies depending on the type of silicone compound and the degree of compatibility with the release agent, but the amount of silicone compound added to the release agent containing dimethylpolysiloxane as a main component varies depending on the type of silicone compound and the degree of compatibility with the release agent. The setting may be made in consideration of the desired peeling voltage when peeling from the substrate, contamination resistance to the adherend, adhesive properties, etc.

The antistatic agent constituting the release agent layer 4 is one that has good dispersibility in a release agent solution containing dimethylpolysiloxane as its main component, and inhibits curing of the release agent containing dimethylpolysiloxane as its main component. Preferably one that does not. Alkali metal salts are suitable as such antistatic agents.

Examples of alkali metal salts include metal salts consisting of lithium, sodium, and potassium. Specifically, for example, cations consisting of Li ⁺ , Na ⁺ , and K ⁺ , and cations consisting of Cl ⁻ , Br ⁻ , I ⁻ , and BF ₄ ^- , PF ₆ ^- , SCN ^- , ClO ₄ ^- , CF ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (CF ₃ SO ₂ ) ₃ C ^- Metal salts composed of anions consisting of the following are preferably used. Among them, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, Li(C ₂ F ₅ SO ₂ ) ₂ N, Li(CF ₃ Lithium salts such as SO ₂ ) ₃ C are preferably used. These alkali metal salts may be used alone or in combination of two or more. A compound containing a polyoxyalkylene structure may be added to stabilize the ionic substance.
The amount of antistatic agent added to the release agent whose main component is dimethylpolysiloxane varies depending on the type of antistatic agent and the degree of affinity with the release agent, but when peeling the antistatic surface protection film from the adherend. It may be set in consideration of the desired peeling voltage, contamination of the adherend, adhesive properties, etc.

There are no particular limitations on the method of mixing the release agent containing dimethylpolysiloxane as a main component, the polyether-modified silicone, and the antistatic agent. A method in which a polyether-modified silicone and an antistatic agent are added to a release agent whose main component is dimethylpolysiloxane, and after mixing, a catalyst for curing the release agent is added and mixed; a release agent whose main component is dimethylpolysiloxane. A method in which a release agent containing siloxane as a main component is diluted in an organic solvent in advance, and then polyether-modified silicone, an antistatic agent, and a catalyst for curing the release agent are added and mixed; Any method may be used, such as adding and mixing polyether-modified silicone and an antistatic agent. Further, if necessary, an adhesion improver such as a silane coupling agent or a material that assists in antistatic effect such as a compound containing a polyoxyalkylene group may be added.

The mixing ratio of the release agent containing dimethylpolysiloxane as the main component, the polyether-modified silicone, and the antistatic agent is not particularly limited; The solid content of the polyether-modified silicone and antistatic agent is preferably about 5 to 100. If the amount of polyether-modified silicone and antistatic agent added in terms of solid content is less than 5 parts per 100 solid content of the release agent whose main component is dimethylpolysiloxane, the surface of the adhesive layer will be prevented from charging. The amount of agent transferred also decreases, making it difficult for the adhesive to perform its antistatic function. In addition, if the added amount of polyether-modified silicone and antistatic agent in terms of solid content exceeds 100% of the solid content of the release agent whose main component is dimethylpolysiloxane, polyether-modified silicone and antistatic agent Since the release agent containing dimethylpolysiloxane as a main component is also transferred to the surface of the pressure-sensitive adhesive layer, there is a possibility that the adhesive properties of the pressure-sensitive adhesive may be deteriorated.

The method of forming the adhesive layer 2 and the method of bonding the release film 5 to the base film 1 of the antistatic surface protection film 10 according to the present invention may be performed by any known method and are not particularly limited. Specifically, (1) a method of applying a resin composition for forming the adhesive layer 2 on one side of the base film 1, drying it to form the adhesive layer, and then laminating the release film 5; (2) Examples include a method of applying and drying a resin composition for forming the adhesive layer 2 on the surface of the release film 5 to form the adhesive layer, and then laminating the base film 1. Either method may be used.

Further, the adhesive layer 2 may be formed on the surface of the base film 1 by a known method. Specifically, known coating methods such as reverse coating, comma coating, gravure coating, slot die coating, Meyer bar coating, and air knife coating can be used.

Similarly, the release agent layer 4 may be formed on the resin film 3 by a known method. Specifically, known coating methods such as gravure coating, Mayer bar coating, and air knife coating can be used.

FIG. 2 is a sectional view showing a state in which a release film has been peeled off from the antistatic surface protection film of the present invention.
By peeling off the release film 5 from the antistatic surface protection film 10 shown in FIG. A portion is transferred (attached) to the surface of the adhesive layer 2 of the antistatic surface protection film 10. Therefore, in FIG. 2, the silicone compound and the antistatic agent, which are liquid at 20° C. and which are transferred to the surface of the adhesive layer 2 of the antistatic surface protection film, are schematically indicated by spots 7.
In the antistatic surface protection film according to the present invention, when the antistatic surface protection film 11 with the release film shown in FIG. Furthermore, the liquid silicone compound and antistatic agent come into contact with the surface of the adherend at 20°C. As a result, the peeling voltage when the antistatic surface protection film is peeled off from the adherend can be kept low.

FIG. 3 is a sectional view showing an embodiment of the optical component of the present invention.
The release film 5 is peeled off from the antistatic surface protection film 10 of the present invention, and with the adhesive layer 2 exposed, it is bonded to an optical component 8 as an adherend via the adhesive layer 2. Ru.
That is, FIG. 3 shows an optical component 20 to which the antistatic surface protection film 10 of the present invention is laminated. Examples of optical components include optical films such as polarizing plates, retardation plates, lens films, polarizing plates that also serve as retardation plates, and polarizing plates that also serve as lens films. Such optical components are used as constituent members of liquid crystal display devices such as liquid crystal display panels, optical system devices of various instruments, and the like. Examples of optical components include optical films such as antireflection films, hard coat films, and transparent conductive films for touch panels. In particular, optical films such as low-reflection polarizing plates (LR polarizing plates) and anti-glare low-reflection polarizing plates (AG-LR polarizing plates) whose surfaces are anti-staining treated with silicone compounds or fluorine compounds, etc. It can be suitably used as an antistatic surface protection film that is bonded to a contaminated surface.
According to the optical component of the present invention, when the antistatic surface protection film 10 is peeled off and removed from the optical component (optical film) that is the adherend, the peeling electrostatic voltage can be suppressed to a sufficiently low level. There is no risk of destroying circuit components such as ICs, TFT elements, and gate line drive circuits, and it is possible to increase production efficiency in the process of manufacturing liquid crystal display panels and the like, and maintain reliability in the production process.

Next, the present invention will be further explained by examples.

<Manufacture of adhesive composition>
[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 gas. Thereafter, 100 parts by weight of 2-ethylhexyl acrylate, 3.0 parts by weight of 8-hydroxyoctyl acrylate, and 10 parts by weight of polypropylene glycol monoacrylate (average repeating number of alkylene oxide constituting the polyalkylene glycol chain n = 12) were added to the reactor. 60 parts by weight of a solvent (ethyl acetate) was added. Thereafter, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise over 2 hours, and the reaction was carried out at 65°C for 6 hours to form the acrylic copolymer solution of Example 1 with a weight average molecular weight of 500,000. Obtained. To this acrylic copolymer solution, 8.5 parts by weight of acetylacetone was added and stirred, followed by 2.0 parts by weight of Coronate HX (isocyanurate of hexamethylene diisocyanate compound) and 0.1 part by weight of titanium trisacetylacetonate. The pressure-sensitive adhesive composition of Example 1 was obtained by stirring and mixing.

[Examples 2 to 6 and Comparative Examples 1 to 2]
The adhesive compositions of Examples 2 to 6 and Comparative Examples 1 to 2 were prepared in the same manner as in Example 1, except that the compositions of the adhesive compositions of Example 1 were changed as shown in Tables 1 and 2, respectively. I got something.

Tables 1 and 2 are two separate tables showing the blending ratio of each component, and in both cases, the parts by weight calculated based on the total of group (A) being 100 parts by weight are enclosed in parentheses. Indicated by Further, the compound names of the abbreviations for each component used in Tables 1 and 2 are shown in Tables 3 and 4. Furthermore, Coronate (registered trademark) HX, Coronate HL, and Coronate L are the product names of Japan Polyurethane Industries, Ltd., and Takenate (registered trademark) D-140N, D-127N, and D-110N are the product names of Mitsui Chemicals, Inc. Desmodur (registered trademark) N3400 is a product name of Sumika Bayer Urethane Co., Ltd.

<Synthesis of bifunctional isocyanate compound>
The bifunctional isocyanate compounds of Synthesis Examples 1 and 2 were synthesized by the following method. As shown in Tables 5 and 6, diisocyanate and diol compounds were mixed at a molar ratio of NCO/OH=16, reacted at 120°C for 3 hours, and then reacted under reduced pressure using a thin film evaporator. Unreacted diisocyanate was removed to obtain the desired bifunctional isocyanate compound.

<Preparation of antistatic surface protection film>
[Example 1]
5 parts by weight of addition reaction silicone (manufactured by Dow Corning Toray Co., Ltd., product name: SRX-345), 0.15 parts by weight of polyether-modified silicone (manufactured by Dow Corning Toray Co., Ltd., product name: SH8400), perchloric acid 5 parts by weight of a 10% lithium ethyl acetate solution, 95 parts by weight of a 1:1 mixed solvent of toluene and ethyl acetate, and 0.05 parts by weight of a platinum catalyst (manufactured by Dow Corning Toray Co., Ltd., product name: SRX-212 Catalyst). were mixed and stirred to prepare a paint for forming the release agent layer of Example 1. The paint forming the release agent layer of Example 1 was applied to the surface of a polyethylene terephthalate film with a thickness of 38 μm using a Meyer bar so that the thickness after drying was 0.2 μm, and the coating was heated in a hot air circulation oven at 120°C. The film was dried for 1 minute to obtain the release film of Example 1.
The adhesive composition of Example 1 was applied to the surface of a polyethylene terephthalate film with a thickness of 38 μm so that the thickness after drying was 20 μm, and then dried for 2 minutes in a hot air circulation oven at 100 ° C. An adhesive layer was formed. Thereafter, the release agent layer (silicone treated surface) of the release film of Example 1 prepared above was laminated on the surface of this adhesive layer. The obtained adhesive film was kept warm in an environment of 40° C. for 5 days to cure the adhesive, thereby obtaining the antistatic surface protection film of Example 1.

[Examples 2 to 6]
Antistatic surface protection films of Examples 2 to 6 were obtained in the same manner as in Example 1, except that the adhesive compositions of Example 1 were replaced with the adhesive compositions of Examples 2 to 6, respectively.

[Comparative example 1]
5 parts by weight of addition reaction silicone (manufactured by Dow Corning Toray Co., Ltd., product name: SRX-345), 95 parts by weight of a 1:1 mixed solvent of toluene and ethyl acetate, and a platinum catalyst (manufactured by Dow Corning Toray Co., Ltd.) , product name: SRX-212 Catalyst) and stirred and mixed to prepare a paint for forming the release agent layer of Comparative Example 1. The paint forming the release agent layer of Comparative Example 1 was applied to the surface of a polyethylene terephthalate film with a thickness of 38 μm using a Meyer bar so that the thickness after drying was 0.2 μm, and the coating was heated in a hot air circulation oven at 120°C. The film was dried for 1 minute to obtain a release film of Comparative Example 1.
The adhesive composition of Comparative Example 1 was applied to the surface of a polyethylene terephthalate film with a thickness of 38 μm so that the thickness after drying was 20 μm, and then dried in a hot air circulation oven at 100° C. for 2 minutes. An adhesive layer was formed. Thereafter, the release agent layer (silicone treated surface) of the release film of Comparative Example 1 prepared above was laminated on the surface of this adhesive layer. The obtained adhesive film was kept warm in an environment of 40° C. for 5 days to cure the adhesive, thereby obtaining an antistatic surface protection film of Comparative Example 1.

[Comparative example 2]
An antistatic surface protection film of Comparative Example 2 was obtained in the same manner as Comparative Example 1 except that the adhesive composition of Comparative Example 1 was replaced with the adhesive composition of Comparative Example 2.

Table 7 shows the composition and thickness of the release agent layer in the antistatic surface protection films of Examples 1 to 6 and Comparative Examples 1 and 2.

<Test method and evaluation>
After aging the surface protection films in Examples 1 to 6 and Comparative Examples 1 and 2 for 7 days in an atmosphere of 23°C and 50% RH, the release film (silicone resin coated PET film) was peeled off and the adhesive was removed. The sample with the agent layer exposed was used as a sample for measuring surface resistivity.
Furthermore, the surface protection film with this adhesive layer exposed was pasted on the surface of the polarizing plate attached to the liquid crystal cell via the adhesive layer, and after being left for one day, the film was heated at 50°C, 5 atm, for 20 minutes. The samples that were autoclaved and left at room temperature for an additional 12 hours were used as measurement samples for adhesive strength, peeling voltage, and reworkability.

<Adhesive strength>
The measurement sample obtained above (a 25 mm wide surface protective film laminated to the surface of a polarizing plate) was peeled in a 180° direction using a tensile tester at a low peeling speed (0.3 m/min) and a high peeling speed. The adhesive strength was measured by peeling at a peeling speed of 30 m/min.

<Surface resistivity>
After aging, before bonding to the polarizing plate, peel off the release film (silicone resin coated PET film) to expose the adhesive layer, and use a resistivity meter Hiresta UP-HT450 (manufactured by Mitsubishi Chemical Analytech) to expose the adhesive layer. The surface resistivity of the adhesive layer was measured.

<Peeling voltage>
When the measurement sample obtained above was peeled 180° at a tensile speed of 30 m/min, the voltage (charged voltage) generated when the polarizing plate was charged was measured using high-precision electrostatic sensors SK-035 and SK-200 (stock (manufactured by Keyence Corporation), and the maximum value of the measured value was taken as the peeling electrostatic voltage.

<Reworkability>
After tracing the surface protective film of the measurement sample obtained above with a ballpoint pen (load 500 g, 3 reciprocations), peel off the surface protective film from the polarizing plate and observe the surface of the polarizing plate. It was confirmed that there was no migration. The evaluation target criteria are "○" if there is no contamination transfer to the polarizing plate, "△" if contamination transfer is confirmed at least in part along the trajectory traced with a ballpoint pen, and "△" if contamination transfer is confirmed at least in part along the trajectory traced with a ballpoint pen. Cases in which contamination transfer was confirmed and detachment of the adhesive from the adhesive surface was also confirmed were evaluated as "x".

Table 8 shows the evaluation results. Note that the surface resistivity was expressed by a method in which "m×10 ⁺ⁿ " is expressed as "mE+n" (where m is an arbitrary real value and n is a positive integer).

From the measurement results shown in Table 8, the following can be seen.
The antistatic surface protection films of Examples 1 to 6 according to the present invention have appropriate adhesion, do not contaminate the surface of the adherend, and have a high temperature resistance when the antistatic surface protection film is peeled off from the adherend. Peeling voltage is low.
On the other hand, in the antistatic surface protection film of Comparative Example 1 in which a silicone compound and an antistatic agent were added to the adhesive layer, the surface resistivity of the adhesive layer was low and good, but the peeling voltage was low due to the high adhesive strength. It was expensive and had poor reworkability. Furthermore, in Comparative Example 2, although the adhesive had a suitable adhesive strength, the surface resistivity of the adhesive layer was high, so the peeling voltage was high and the reworkability was poor.
That is, in Comparative Examples 1 and 2 in which a silicone compound and an antistatic agent are mixed in the adhesive, it is difficult to achieve both a reduction in peeling electrostatic voltage and a stain resistance to the adherend. On the other hand, in Examples 1 to 6, in which a silicone compound and an antistatic agent were added to the release agent layer and then transferred to the surface of the adhesive layer, the release charge voltage was increased with a small amount of addition. Because of the reduction effect, a good antistatic surface protection film was obtained without contaminating the adherend.

The antistatic surface protection film of the present invention can be used, for example, on the surface of optical parts, such as optical films such as polarizing plates, retardation plates, display lens films, and other various optical parts. can be used to protect In particular, when used as an antistatic surface protection film for optical films such as LR polarizing plates and AG-LR polarizing plates whose surfaces have been treated with anti-staining agents such as silicone compounds or fluorine compounds, the film may peel off from the adherend. When doing so, the amount of static electricity generated can be reduced.
The antistatic surface protection film of the present invention causes less contamination of adherends, and has excellent peeling antistatic performance without degrading over time, so it can improve the yield of the production process and has industrial utility value. is large.

DESCRIPTION OF SYMBOLS 1... Base film, 2... Adhesive layer, 3... Resin film, 4... Release agent layer, 5... Release film, 7... Silicone compound and antistatic agent liquid at 20°C, 8... Adherent (optical Components), 10...Antistatic surface protection film, 11...Antistatic surface protection film from which the release film has been peeled off, 20...An optical component to which the antistatic surface protection film is laminated.

Claims (2)

An antistatic surface protection film in which an adhesive layer is formed on one side of a base film, and a release film is laminated on the adhesive layer,
The adhesive layer is formed by crosslinking an adhesive composition containing an acrylic polymer and a crosslinking agent,
The acrylic polymer is copolymerizable with (A) at least one (meth)acrylic acid ester monomer whose alkyl group has a carbon number of C4 to C18, and (B) a copolymerizable monomer containing a hydroxyl group. As a monomer group, (C) a copolymerizable monomer containing a carboxyl group, (D) a polyalkylene glycol mono(meth)acrylic acid ester monomer, and (E) a nitrogen-containing vinyl monomer that does not contain a hydroxyl group or a hydroxyl group. Consisting of a copolymer obtained by copolymerizing an alkyl (meth)acrylate monomer containing no alkoxy group and at least one selected from a group of copolymerizable monomers consisting of,
The copolymerizable monomer containing a hydroxyl group (B) is 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate. , N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and N-hydroxyethyl(meth)acrylamide,
The crosslinking agent is a difunctional or more functional isocyanate compound,
The release film is formed by laminating a release agent layer containing an antistatic agent on one side of a resin film,
The release agent layer is formed of a resin composition containing a release agent containing dimethylpolysiloxane as a main component, a silicone compound that is liquid at 20°C, and an antistatic agent,
An antistatic surface protection film, wherein the silicone compound and the antistatic agent contained in the release agent layer are transferred only to the surface of the adhesive layer. An optical film using the antistatic surface protection film according to claim 1.

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