JP6876855B2 - Release film for antistatic surface protection film - Google Patents

Description

The present invention relates to pressure-sensitive adhesive compositions and surface protective films. More specifically, the present invention relates to an antistatic surface protective film having antistatic performance. More specifically, the present invention provides a method for producing an antistatic surface protective film, which is less contaminated with an adherend and has excellent peeling antistatic performance without deterioration over time, and an antistatic surface protective film.

When manufacturing and transporting optical films such as polarizing plates, retardation plates, lens films for displays, antireflection films, hard coat films, transparent conductive films for touch panels, and optical products such as displays using them. Is made by sticking a surface protective film on the surface of the optical film to prevent the surface from being soiled or scratched in a subsequent step. The appearance inspection of the optical film, which is a product, may be performed with the surface protective film attached to the optical film in order to save the trouble of peeling off the surface protective film and attaching it again to improve work efficiency.
Conventionally, a surface protective film having an adhesive layer provided on one side of a base film has been generally used in the manufacturing process of an optical product in order to prevent the adhesion of scratches and stains. The surface protective film is attached to the optical film via an adhesive layer having a slight adhesive strength. The reason why the adhesive layer has a slight adhesive strength is that the used surface protective film can be easily peeled off when it is peeled off from the surface of the optical film, and the adhesive is an adherend of the product. This is to prevent the adhesive from adhering to the optical film and remaining (so-called adhesive residue is prevented).

In recent years, in the production process of a liquid crystal display panel, the display screen of the liquid crystal display panel is controlled by the peeling band voltage generated when the surface protective film bonded on the optical film is peeled off and removed. Although the number of occurrences is small, the phenomenon that circuit parts such as driver ICs are destroyed and the phenomenon that the orientation of liquid crystal molecules is damaged are occurring.
Further, in order to reduce the power consumption of the liquid crystal display panel, the driving voltage of the liquid crystal material is getting lower, and the breaking voltage of the driver IC is also getting lower accordingly. Recently, it has been required to set the peeling band voltage within the range of +0.7 kV to −0.7 kV.
Therefore, when the surface protective film is peeled from the optical film as an adherend, an adhesive layer containing an antistatic agent for suppressing the peeling band voltage is prevented in order to prevent a problem due to a high peeling band voltage. A surface protective film using the above has been proposed.

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

Japanese Unexamined Patent Publication No. 2005-131957 Japanese Unexamined Patent Publication No. 2005-330464 Japanese Unexamined Patent Publication No. 2005-314476 Japanese Unexamined Patent Publication No. 2006-152235 Japanese Unexamined Patent Publication No. 2009-275128 Japanese Patent No. 4537450

In Patent Documents 1 to 4 described above, an antistatic agent is added to the inside of the pressure-sensitive adhesive layer, but the surface protective film is bonded as the thickness of the pressure-sensitive adhesive layer increases and as the elapsed time elapses. The amount of antistatic agent transferred from the pressure-sensitive adhesive layer to the adherend increases with respect to the adherend. Further, in optical films such as LR (Low Reflective) polarizing plates and AG (AntiGale) -LR polarizing plates, the surface of the optical film is treated with a silicone compound, a fluorine compound, or the like to prevent stains. When the surface protective film used for the optical film is peeled off from the optical film as an adherend, the peeling band voltage becomes high.

Further, when the polyether-modified silicone described in Patent Documents 5 and 6 is mixed in the pressure-sensitive adhesive layer, it is difficult to finely adjust the adhesive strength of the surface protective film. Further, since the polyether-modified silicone is mixed in the pressure-sensitive adhesive layer, when the conditions for coating and drying the pressure-sensitive adhesive composition on the base film change, the pressure-sensitive adhesive layer on which the surface protective film is formed The surface properties change subtly. Further, from the viewpoint of protecting the surface of the optical film, the thickness of the pressure-sensitive adhesive layer cannot be made extremely thin. Therefore, it is necessary to increase the amount of the polyether-modified silicone mixed in the pressure-sensitive adhesive layer according to the thickness of the pressure-sensitive adhesive layer. The contamination of the adherend changes.

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

On the other hand, in some liquid crystal panel makers, as a method of evaluating the contamination of the surface protective film on the adherend, the surface protective film attached to the optical film such as a polarizing plate is once peeled off and air bubbles are mixed. A method is adopted in which the reattached film is heat-treated under predetermined conditions, and then the surface protective film is peeled off to observe the surface of the adherend. In such an evaluation method, even if the surface contamination of the adherend is very small, the difference in surface contamination of the adherend is between the portion where air bubbles are mixed and the portion where the adhesive of the surface protective film is in contact. If there is, it remains as a trace of bubbles (sometimes called bubble stain). Therefore, it is a very strict evaluation method as a method for evaluating the contamination of the surface of the adherend. In recent years, even as a result of judgment by such a strict evaluation method, there is a demand for a surface protective film that does not have a problem of stainability on the surface of the adherend. However, it has been difficult to solve the problem with the conventionally proposed surface protective film using an adhesive layer containing an antistatic agent.

For this reason, there is a need for a surface protective film used for an optical film, which has very little contamination on the adherend and whose stainability on the adherend does not change with time. Further, there is a demand for a surface protective film in which the peeling band voltage at the time of peeling from the adherend is suppressed to a low level.

The present inventors have diligently studied to solve this problem.
In order to reduce the contamination of the adherend and the change in antistatic performance with time, it is necessary to reduce the amount of the antistatic agent added, which is presumed to be the cause of contaminating the adherend. However, when the amount of the antistatic agent added is reduced, the peeling band voltage when the surface protective film is peeled from the adherend becomes high. The present inventors have studied a method of suppressing the peeling band voltage when peeling the surface protective film from the adherend without increasing the absolute amount of the antistatic agent added. As a result, instead of adding an antistatic agent and mixing them to form a pressure-sensitive adhesive layer in the pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition is applied and dried to laminate the pressure-sensitive adhesive layer, and then the pressure-sensitive adhesive is applied. We have found that by applying an appropriate amount of an antistatic agent component to the surface of the layer, the peeling band voltage when the surface protective film is peeled from the optical film as an adherend can be suppressed to a low level, and the present invention has been made. Was completed.

The present invention has been made in view of the above circumstances, and is a method for producing an antistatic surface protective film having less contamination on the adherend and excellent peeling antistatic performance without deterioration over time, and charging. An object of the present invention is to provide a preventive surface protective film.

In order to solve the above problems, the antistatic surface protective film of the present invention is a liquid at an appropriate amount of 20 ° C. on the surface of the pressure-sensitive adhesive layer after the pressure-sensitive adhesive composition is applied and dried to laminate the pressure-sensitive adhesive layer. By adding the silicone-based compound and antistatic agent of the above, the technical idea is to keep the contamination property to the adherend low and to keep the peeling band voltage low when peeling from the optical film which is the adherend. There is.

In order to solve the above problems, in the present invention, a pressure-sensitive adhesive layer is formed on one side of a base film made of a transparent resin, and an antioxidant is transferred to the surface of the pressure-sensitive adhesive layer. , A method for producing an antistatic surface protective film, wherein the pressure-sensitive adhesive layer is composed of an acrylic polymer, (D) a bifunctional or higher functional isocyanate compound, (E) a cross-linking accelerator, and (F) ketoenol copolymer. A pressure-sensitive adhesive layer obtained by cross-linking a pressure-sensitive adhesive composition containing a body compound, wherein the acrylic polymer has at least (meth) acrylic acid ester monomer having (A) alkyl groups having C4 to C18 carbon atoms. As a group of copolymerizable monomers, (B) a copolymerizable monomer containing a hydroxyl group, and (C) a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkoxy group-containing alkyl (meth) acrylate monomer It is an acrylic polymer obtained by copolymerizing at least one selected from the copolymerizable monomer group, and as the ratio of the (F) ketoenol tetherable compound to the (E) cross-linking accelerator. , (E): (F) have a weight ratio of 1:80 to 1: 500, and a release agent layer containing an antioxidant is laminated on one side of the resin film, and the release agent layer is dimethyl. A release film formed of a resin composition containing a release agent containing a polysiloxane as a main component, a silicone-based compound liquid at 20 ° C., and an antistatic agent is formed through the release agent layer to form the pressure-sensitive adhesive layer. The release film is peeled off from the surface of the pressure-sensitive adhesive layer, and the silicone-based compound of the release agent layer and the antistatic agent are transferred only to the surface of the pressure-sensitive adhesive layer. Provided is a method for producing a characteristic antistatic surface protective film.

Further, it is preferable that the copolymerizable monomer group further contains (G) polyalkylene glycol mono (meth) acrylic acid ester monomer.

Further, it is preferable that the (E) cross-linking accelerator is at least one selected from the group consisting of an aluminum chelate compound, a titanium chelate compound, and an iron chelate compound.

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

Further, the (G) polyalkylene glycol mono (meth) acrylic acid ester monomer is selected from polyalkylene glycol mono (meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, and ethoxypolyalkylene glycol (meth) acrylate. Moreover, it is preferable that there is at least one kind or more.

Further, as the (D) bifunctional or higher functional isocyanate compound, the bifunctional isocyanate compound is an acyclic aliphatic isocyanate compound, which is a compound produced by reacting a diisocyanate compound with a diol compound, and is used as a diisocyanate compound. Is an aliphatic diisocyanate, which is one selected from the compound group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate, and 2-methyl-1 as the diol compound. , 3-Propanediol, 2,2-dimethyl-1,3-Propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 3 -Methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol Monohydroxypivalate, polyethylene glycol, polypropylene glycol Consists of a type selected from the compound group, and is a trifunctional isocyanate compound. Examples include isocyanurates of hexamethylene diisocyanate compounds, isocyanurates of isophorone diisocyanate compounds, adducts of hexamethylene diisocyanate compounds, adducts of isophorone diisocyanate compounds, bullets of hexamethylene diisocyanate compounds, and bullets of isophorone diisocyanate compounds. 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 It is preferably composed of a compound adduct.

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

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

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

Further, in order to solve the above problems, in the present invention, on one side of a base film made of a transparent resin, a (meth) acrylic acid ester monomer having (A) alkyl groups having C4 to C18 carbon atoms is used. The copolymerizable monomer group with at least one type does not contain a copolymerizable monomer containing a carboxyl group, but (B) a copolymerizable monomer containing a hydroxyl group and (C) a nitrogen containing no hydroxyl group. Acrylic based on a copolymer obtained by copolymerizing a vinyl-containing monomer or an alkoxy group-containing alkyl (meth) acrylate monomer containing no hydroxyl group and at least one selected from the copolymerizable monomer group. A pressure-sensitive adhesive layer obtained by cross-linking a pressure-sensitive adhesive composition containing a polymer, (D) a bifunctional or higher-functional isocyanate compound, (E) a cross-linking accelerator, and (F) a ketoenol copolymer compound. A release film formed by laminating a release agent layer containing an antioxidant on one side of the resin film on the surface of the pressure-sensitive adhesive layer is bonded via the release agent layer to form the release agent. The layer is formed of a resin composition containing a release agent containing a dimethylpolysiloxane as a main component, a silicone-based compound that is liquid at 20 ° C., and an antioxidant, and is formed only on the surface of the pressure-sensitive adhesive layer. The weight of (E): (F) as the ratio of the (F) ketoenol copolymer compound to the (E) cross-linking accelerator obtained by transferring the silicone-based compound and the antistatic agent in the release agent layer. Provided is an antistatic surface protective film characterized by a ratio of 1:80 to 1: 500.

Further, it is preferable that the copolymerizable monomer group further contains (G) polyalkylene glycol mono (meth) acrylic acid ester monomer.

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

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

The present invention also provides an optical film to which the above antistatic surface protective film is bonded.

The present invention also provides an optical component to which the above antistatic surface protective film is bonded.

The antistatic surface protective film of the present invention has less contamination on the adherend, and the low contamination on the adherend does not change with time. Further, according to the present invention, even if the surface of the adherend, such as an LR polarizing plate or an AG-LR polarizing plate, is antistatically treated with a silicone compound or a fluorine compound, antistatic is prevented. It is possible to provide an antistatic surface protective film which can suppress the peeling band voltage generated when the surface protective film is peeled from an adherend to a low value and has excellent peeling antistatic performance without deterioration over time.
According to the antistatic surface protective film of the present invention, the surface of the optical film can be reliably protected, so that productivity and yield can be improved.

It is sectional drawing which showed the concept of the antistatic surface protection film of this invention. It is sectional drawing which shows the state which peeled off the release film from the antistatic surface protection film of this invention. It is sectional drawing which showed one of Examples of the optical component of this invention.

Hereinafter, the present invention will be described in detail based on the embodiments.
FIG. 1 is a cross-sectional view showing a concept of the antistatic surface protective film of the present invention. In the antistatic surface protective film 10, the pressure-sensitive adhesive layer 2 is formed on the surface of one side of the transparent base film 1. On the surface of the pressure-sensitive adhesive layer 2, a release film 5 having a release agent layer 4 formed on the surface of the resin film 3 is bonded.

As the base film 1 used in the antistatic surface protective film 10 according to the present invention, a base film made of a transparent and flexible resin is used. This makes it possible to inspect the appearance of the optical component in a state where the antistatic surface protective film is attached to the optical component which is an adherend. As the film made of a transparent resin used as the base film 1, a polyester film such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, or polybutylene terephthalate is preferably used. In addition to the polyester film, a film made of another resin can be used as long as it has the required strength and optical suitability. The base film 1 may be a non-stretched film or a uniaxially or biaxially stretched film. Further, the draw ratio of the stretched film and the orientation angle of the axial method formed by crystallization of the stretched film may be controlled to a specific value.
The thickness of the base film 1 used for the antistatic surface protective film 10 according to the present invention is not particularly limited, but is preferably about 12 to 100 μm, and is easy to handle if the thickness is about 20 to 50 μm. , More preferred.
Further, if necessary, an antifouling layer for preventing surface stains, an antistatic layer, a hard coat layer for preventing scratches, and the like are provided on 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 an easy adhesion treatment such as surface modification by corona discharge or application of an anchor coating agent.

Further, the adhesive layer 2 used in the antistatic surface protective 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. If this is the case, the present invention is not particularly limited, but in consideration of durability after bonding to an optical film, it is common to use an acrylic pressure-sensitive adhesive obtained by cross-linking a (meth) acrylate copolymer. ..

In particular, the main agent of the acrylic pressure-sensitive adhesive contains a carboxyl group as a group of monomers copolymerizable with at least one (meth) acrylic acid ester monomer having (A) alkyl groups having C4 to C18 carbon atoms. Copolymerization consisting of (B) a copolymerizable monomer that does not contain a polymerizable monomer but contains a hydroxyl group, and (C) a nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth) acrylate monomer that does not contain a hydroxyl group. A pressure-sensitive adhesive layer made of an acrylic polymer, which is a copolymer of at least one selected from a group of possible monomers, is preferable.
The copolymerizable monomer group may further include (G) polyalkylene glycol mono (meth) acrylic acid ester monomer.
Further, a pressure-sensitive adhesive composition comprising (D) a bifunctional or higher functional isocyanate compound, (E) a cross-linking accelerator, and (F) a keto-enol tautomer compound in addition to the acrylic polymer. The agent layer is preferred.

Examples of the (meth) acrylic acid ester monomer having an alkyl group having C4 to C18 carbon atoms include butyl (meth) acrylate, isobutyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, and heptyl (meth). Meta) 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 Meta) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, myristyl (meth) Examples thereof include acrylate, isomyristyl (meth) acrylate, cetyl (meth) acrylate, isosetyl (meth) acrylate, stearyl (meth) acrylate, and isostearyl (meth) acrylate.
When the total amount of the acrylic polymers of the copolymer is 100 parts by weight, the (A) alkyl group contains 50 to 95 parts by weight of the (meth) acrylic acid ester monomer having C4 to C18 carbon atoms. It is preferable to have.

Examples of the copolymerizable monomer containing the (B) hydroxyl group include 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxyethyl (meth) acrylate. Examples thereof include hydroxyalkyl (meth) acrylates such as N-hydroxy (meth) acrylamide, 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) ) At least one selected from the compound group consisting of acrylamide and N-hydroxyethyl (meth) acrylamide is preferable.
When the total amount of the acrylic polymers of the copolymer is 100 parts by weight, it is preferable that the copolymerizable monomer containing the hydroxyl group (B) is contained in an amount of 0.1 to 10 parts by weight.

It is preferable that the acrylic polymer contains at least one or more of (C) a hydroxyl group-free nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth) acrylate monomer as the copolymerizable monomer group.

Among (C), examples of the (C-1) nitrogen-containing vinyl monomer include a vinyl monomer containing an amide bond, a vinyl monomer containing an amino group, and a vinyl monomer having a nitrogen-containing heterocyclic structure. More specifically, N-vinyl-2-pyrrolidone, N-vinylpyrrolidone, methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinyl. Cyclic nitrogen-vinyl compounds having an N-vinyl-substituted heterocyclic structure, such as pyrrol, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholin, N-vinylcaprolactam, N-vinyllauryllolactum; Meta) acryloyl morpholine, N- (meth) acryloyl piperazine, N- (meth) acryloyl azidine, N- (meth) acryloyl azetidine, N- (meth) acryloyl pyrrolidine, N- (meth) acryloyl piperidine, N- (meta) ) Cyclic nitrogen-vinyl compounds having a heterocyclic structure of N- (meth) acryloyl substitution, such as acryloyl azepan and N- (meth) acryloyl azocan; A cyclic nitrogen-vinyl compound having a heterocyclic structure having an ethylene-based unsaturated bond in the ring; (meth) acrylamide, N-methyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-t-butyl (meth) 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, 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 (Meta) acrylate, N, N-dimethylaminobutyl (meth) acrylate, N, N-diethylaminomethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N-ethyl-N-methylaminoethyl (meth) ) Acrylic, N-methyl-N-propylaminoethyl (meth) acrylate, N-methyl-N-isopropylaminoethyl (me) Dialkylamino (meth) acrylates such as t) acrylate, N, N-dibutylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate; 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, N-dialkyl-substituted aminopropyl (meth) acrylamides such as N-propylaminopropyl (meth) acrylamide, N-methyl-N-isopropylaminopropyl (meth) acrylamide; N-vinylformamide, N-vinylacetamide, N- N-vinylcarboxylic acid amides such as vinyl-N-methylacetamide; N-methoxymethyl (meth) acrylamide, N-ethoxyethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetoneacrylamide, N, N -(Meta) acrylamides such as methylenebis (meth) acrylamide; unsaturated carboxylic acid nitriles such as (meth) acrylonitrile; and the like.

The nitrogen-containing vinyl monomer (C-1) preferably does not contain a hydroxyl group, and more preferably does not contain a hydroxyl group or a carboxyl group. Examples of such a monomer include acrylic monomers containing the above-exemplified monomers such as 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) acryloylpyrrolidin are preferred.

Among (C), examples of the (C-2) alkoxy group-containing alkyl (meth) acrylate monomer include 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, and 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, 3-butoxypropyl (meth) acrylate, 4-methoxybutyl (meth) acrylate, 4-ethoxybutyl (meth) acrylate, 4-propoxybutyl (meth) acrylate, 4-isopropoxybutyl (meth) acrylate, 4- Butoxybutyl (meth) acrylate and the like can be mentioned.
These alkoxy group-containing alkyl (meth) acrylate monomers have a structure in which the alkyl group atom in the alkyl (meth) acrylate is substituted with an alkoxy group.

When the total amount of the acrylic polymers of the copolymer is 100 parts by weight, 0 to 20 parts by weight of (C-1) hydroxyl group-free nitrogen-containing vinyl monomer or (C-2) alkoxy group-containing alkyl (meth) acrylate monomer is used. It is preferably contained in a proportion of parts. (C-1) A nitrogen-containing vinyl monomer containing no hydroxyl group and (C-2) an alkyl (meth) acrylate monomer containing an alkoxy group can be used alone or in combination of two or more. In the pressure-sensitive adhesive layer according to the present invention, the pressure-sensitive adhesive composition may not contain (C) a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkoxy group-containing alkyl (meth) acrylate monomer.

(D) The bifunctional or higher functional isocyanate compound may be at least one or more selected from polyisocyanate compounds having at least two or more isocyanate (NCO) groups in one molecule. Polyisocyanate compounds are classified into aliphatic isocyanates, aromatic isocyanates, acyclic isocyanates, alicyclic isocyanates, and the like, but any of them may be used. Specific examples of the polyisocyanate compound include aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and trimethylhexamethylene diisocyanate (TMDI), diphenylmethane diisocyanate (MDI), and xylylene diisocyanate (XDI). , Aromatic isocyanate compounds such as hydrogenated xylylene diisocyanate (H6XDI), dimethyldiphenylenediocyanate (TOID), and tolylene diisocyanate (TDI).
Examples of the trifunctional or higher functional isocyanate compound include a bullet-modified compound of a bifunctional isocyanate compound (a compound having two NCO groups in one molecule), an isocyanurate-modified compound, and trivalent or higher valents such as trimethylolpropane (TMP) and glycerin. Examples thereof include an adduct (modified polyol) with a polyol (a compound having at least 3 or more OH groups in one molecule).
As the (D) bifunctional or higher functional isocyanate compound, it is also possible to use only the (D-1) trifunctional isocyanate compound or only the (D-2) bifunctional isocyanate compound. It is also possible to use the (D-1) trifunctional isocyanate compound and the (D-2) bifunctional isocyanate compound in combination.

Further, as the (D-1) trifunctional isocyanate compound used in the present invention, an isocyanurate form of a hexamethylene diisocyanate compound, an isocyanurate form of an isophorone diisocyanate compound, an adduct form of a hexamethylene diisocyanate compound, an adduct form of an isophorone diisocyanate compound, and the like. At least one selected from the (D-1-1) first aliphatic isocyanate compound group consisting of a burette of a hexamethylene diisocyanate compound and a burette of an isophorone diisocyanate compound, and a tolylene diisocyanate compound. Isocyanurate, 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 contain at least one selected from the group of (D-1-2) second aromatic isocyanate compounds comprising. It is preferable to use (D-1-1) the first aliphatic isocyanate compound group and (D-1-2) the second aromatic isocyanate compound group in combination. In the present invention, as the (D-1) trifunctional isocyanate compound, at least one selected from the (D-1-1) first aliphatic isocyanate compound group and (D-1-2). ) By using at least one selected from the second aromatic isocyanate compound group in combination, the balance of adhesive strength between the low-speed peeling region and the high-speed peeling region can be further improved.

Further, the (D-1) trifunctional isocyanate compound includes at least one selected from the (D-1-1) first aliphatic isocyanate compound group and the above (D-1-2). ) Contains at least one selected from the second aromatic isocyanate compound group, and contains 0.5 to 5.0 parts by weight in total with respect to 100 parts by weight of the copolymer. Is preferable. In addition, at least one selected from the (D-1-1) first aliphatic isocyanate compound group and (D-1-2) second aromatic isocyanate compound group. The mixing ratio with at least one selected from the above is that (D-1-1) :( D-1-2) is in the range of 10%: 90% to 90%: 10% by weight. Is preferable.

Further, the (D-2) bifunctional isocyanate compound used in the present invention is preferably an acyclic aliphatic isocyanate compound, which is produced by reacting a diisocyanate compound with a diol compound.
For example, a diisocyanate compound has a general formula "O = C = N-X-N = C = O" (where X is a divalent group), and a general formula "HO-Y-OH" (where Y is a divalent group). ) Represents a diol compound, and examples of the compound produced by reacting the diisocyanate compound with the diol compound include a compound represented by the following general formula Z.

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

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

The diisocyanate compound represented by the general formula "O = C = N-X-N = C = O" is an aliphatic diisocyanate. X is preferably an acyclic and aliphatic divalent group. The aliphatic diisocyanate preferably comprises one or more selected from the compound group 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 and aliphatic divalent group. Examples of the diol compound include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, and 2-ethyl-2. -From the compound group consisting of butyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxypivalate, polyethylene glycol, and polypropylene glycol. It preferably consists of one or more selected species.

The weight ratio (D-1 / D-2) of the (D-1) trifunctional isocyanate compound to the (D-2) bifunctional isocyanate compound is preferably 1 to 90. The amount of the (D) bifunctional or higher functional isocyanate compound is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the acrylic polymer.

The (E) cross-linking accelerator may be a substance that functions as a catalyst for the reaction (cross-linking reaction) between the copolymer and the cross-linking agent when the polyisocyanate compound is used as the cross-linking agent, and is a tertiary amine. Examples thereof include amine compounds such as, metal chelate compounds, organic tin compounds, organic lead compounds, and organic metal compounds such as organozinc compounds. In the present invention, a metal chelate compound or an organic tin compound is preferable as the cross-linking accelerator.

The metal chelate compound is a compound in which one or more polydentate ligands L are bonded to the central metal atom M. The metal chelate compound may or may not have one or more bidentate ligands X that bind 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 may be the same ligand or may be different ligands. When n is 2 or more, n Xs 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 polydentate ligand L include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetic acid, lauryl acetoacetic acid, and stearyl acetoacetic acid, acetylacetone (also known as 2,4-pentandione), Examples thereof include β-diketones such as 2,4-hexanedione and benzoylacetone. These are keto-enol tautomeric compounds and may be enol-deprotonated enolates (eg, acetylacetonate) in the polydentate ligand L.
The monodentate ligand X includes halogen atoms such as chlorine atom and bromine atom, pentanoyl group, hexanoyl group, 2-ethylhexanoyl group, octanoyl group, nonanoyl group, decanoyyl group, dodecanoyl group, octadecanoyl group and other acyloxy. Examples thereof include an alkoxy group such as a group, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group and a butoxy group.

Specific examples of the metal chelate compound include tris (2,4-pentanedionato) iron (III), iron trisacetylacetonate, titaniumtrisacetylacetonate, rutheniumtrisacetylacetonate, zinc bisacetylacetonate, and aluminum tris. Acetylacetonate, zirconite tetrakis acetylacetonate, tris (2,4-hexanedionat) iron (III), bis (2,4-hexanedionat) zinc, tris (2,4-hexanedionat) titanium, tris Examples thereof include (2,4-hexane dionat) aluminum and tetrakis (2,4-hexane dionate) zirconium.

Examples of the organic tin compound include dialkyltin oxide, a fatty acid salt of dialkyltin, and a fatty acid salt of first tin. 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, a long-chain alkyl tin compound such as a dioctyl tin compound is preferable. Specific examples of the organic tin compound include dioctyl tin oxide and dioctyl tin dilaurate. Sn compounds can be used provisionally, but in the future, in view of the trend that the use of safer substances is required, Al, Ti, Fe, etc., which are safer than Sn, etc. It is preferable to use a metal chelate compound.
The (E) cross-linking accelerator in the pressure-sensitive adhesive composition according to the present invention is preferably at least one selected from the group consisting of an aluminum chelate compound, a titanium chelate compound, and an iron chelate compound.
The cross-linking accelerator (E) is preferably contained in an amount of 0.001 to 0.5 parts by weight with respect to 100 parts by weight of the copolymer.

(F) Examples of the ketoenol tether compound include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetic acid, lauryl acetoacetic acid, and stearyl acetoacetic acid, and acetylacetone and 2,4-hexanedione. , Β-diketone such as benzoylacetone. In a pressure-sensitive adhesive composition using a polyisocyanate compound as a cross-linking agent, these prevent excessive increase in viscosity and gelation of the pressure-sensitive adhesive composition after blending the cross-linking agent by blocking the isocyanate group contained in the cross-linking agent. , The pot life of the pressure-sensitive adhesive composition can be extended.
The keto-enol 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.

Since the (F) keto-enol tautomer compound has an effect of suppressing cross-linking as opposed to the (E) cross-linking accelerator, the ratio of the (F) keto-enol tautomer compound to the (E) cross-linking accelerator Is preferably set appropriately. In order to prolong the pot life of the pressure-sensitive adhesive composition and improve the storage stability, the weight ratio of (E): (F) is preferably in the range of 1: 1 to 1: 500, and more preferably. It is 1:30 to 1: 500, most preferably 1:80 to 1: 500.

The acrylic polymer can optionally further contain (G) polyalkylene glycol mono (meth) acrylic acid ester monomer as the copolymerizable monomer group. The (G) polyalkylene glycol mono (meth) acrylic acid ester monomer may be a compound in which one hydroxyl group of the plurality of hydroxyl groups of the polyalkylene glycol is esterified as a (meth) acrylic acid ester. Since the (meth) acrylic acid ester group becomes a polymerizable group, it can be copolymerized with the main polymer. The other hydroxyl group may be OH as it is, or may be an alkyl ether such as methyl ether or ethyl ether, a saturated carboxylic acid ester such as an acetate ester, or the like.
Examples of the alkylene group contained in the polyalkylene glycol include, but are not limited to, an ethylene group, a propylene group, and a butylene group. The polyalkylene glycol may be a copolymer of two or more kinds of polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol. Examples of the copolymer 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.
It is preferable that the polyalkylene glycol mono (meth) acrylic acid ester monomer (G) has an average number of repetitions of alkylene oxides constituting the polyalkylene glycol chain of 3 to 14. The "average number of repetitions of alkylene oxide" is the average number of repetitions of the alkylene oxide unit in the portion of the "polyalkylene glycol chain" contained in the molecular structure of the (G) polyalkylene glycol mono (meth) acrylic acid ester monomer. is there.

The (G) polyalkylene glycol mono (meth) acrylic acid ester monomer was selected from polyalkylene glycol mono (meth) acrylate, methoxypolyalkylene glycol (meth) acrylate, and ethoxypolyalkylene glycol (meth) acrylate. It is preferable that there is at least one kind or more.
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-polyethylene glycol-polybutylene glycol-mono (meth) acrylate; methoxypolyethylene glycol- (meth) acrylate, methoxypolyethylene glycol -(Meta) acrylate, methoxypolyethylene glycol- (meth) acrylate, methoxy-polyethylene glycol-polypropylene glycol- (meth) acrylate, methoxy-polyethylene glycol-polybutylene glycol- (meth) acrylate, methoxy-polyethylene glycol-polybutylene Glycol- (meth) acrylate, methoxy-polyethylene glycol-polypropylene glycol-polybutylene glycol- (meth) acrylate; ethoxypolyethylene glycol- (meth) acrylate, ethoxypolyethylene glycol- (meth) acrylate, ethoxypolybutylene glycol- (meth) Acrylate, ethoxy-polyethylene glycol-polyethylene glycol- (meth) acrylate, ethoxy-polyethylene glycol-polybutylene glycol- (meth) acrylate, ethoxy-polyethylene glycol-polybutylene glycol- (meth) acrylate, ethoxy-polyethylene glycol-polypropylene glycol -Polybutylene glycol- (meth) acrylate and the like.
When the total amount of the acrylic polymers of the copolymer is 100 parts by weight, it is preferable that the (G) polyalkylene glycol mono (meth) acrylic acid ester monomer is contained in a ratio of 0 to 50 parts by weight. In the pressure-sensitive adhesive layer according to the present invention, the pressure-sensitive adhesive composition may not contain the (G) polyalkylene glycol mono (meth) acrylic acid ester monomer.

The pressure-sensitive adhesive composition can optionally contain the (H) polyether-modified siloxane compound. The (H) polyether-modified siloxane compound is a siloxane compound having a polyether group, and is a siloxane unit having a polyether group [-SiR ¹ (R ^{)] in addition to the usual siloxane unit [-SiR 1} _2-O-]. ^{It has 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 groups). Examples of the polyether group include a polyoxyalkylene group such as a polyoxyethylene group [(C ₂ H ₄ O) _n ] and a polyoxypropylene group [(C ₃ H ₆ O) _n ].

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

The (H) polyether-modified siloxane compound can be obtained, for example, by grafting an organic compound having an unsaturated bond and a polyoxyalkylene group on a polyorganosiloxane main chain having a silicon hydride group by a hydrosilylation reaction. it can. Specifically, dimethylsiloxane / methyl (polyoxyethylene) siloxane copolymer, dimethylsiloxane / methyl (polyoxyethylene) siloxane / methyl (polyoxypropylene) siloxane copolymer, dimethylsiloxane / methyl (polyoxypropylene) Examples thereof include a siloxane polymer.
By blending the (H) polyether-modified siloxane compound into the pressure-sensitive adhesive composition, the adhesive strength and rework performance of the pressure-sensitive adhesive can be improved. If the pressure-sensitive adhesive composition does not contain a polyether-modified siloxane compound, the cost will be lower.

Further, as other components, copolymerizable (meth) acrylic monomer containing alkylene oxide, (meth) acrylamide monomer, dialkyl-substituted acrylamide monomer, surfactant, curing accelerator, plasticizer, filler, curing retarder, Known additives such as processing aids, antioxidants, and antioxidants can be appropriately added. These may be used alone or in combination of two or more.

The main agent copolymer used in the pressure-sensitive adhesive composition of the present invention is a group of monomers copolymerizable with at least one (meth) acrylic acid ester monomer having (A) alkyl groups having C4 to C18 carbon atoms. It is selected from the copolymerizable monomer group consisting of (B) a copolymerizable monomer containing a hydroxyl group and (C) a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkoxy group-containing alkyl (meth) acrylate monomer. It can be synthesized by copolymerizing with at least one kind. The copolymerizable monomer group may further contain (G) polyalkylene glycol mono (meth) acrylic acid ester monomer. The polymerization method of the copolymer is not particularly limited, and an appropriate polymerization method such as solution polymerization or emulsion polymerization can be used.
The pressure-sensitive adhesive composition of the present invention comprises the above-mentioned copolymer, (D) a bifunctional or higher functional isocyanate compound, (E) a cross-linking accelerator, (F) a keto-enol tautomer compound, and an optional additive as appropriate. Can be prepared by blending.

The copolymer is preferably an acrylic polymer, and preferably contains 50 to 100% by weight of an acrylic monomer such as (meth) acrylic acid ester monomer, (meth) acrylic acid, and (meth) acrylamides.
Since the acrylic polymer does not contain a copolymerizable monomer containing a carboxyl group as a copolymerizable monomer group, it is effective in improving the crosslinking rate and stabilizing the adhesive strength. As the monomer that reacts with the (D) bifunctional or higher functional isocyanate compound used as a cross-linking agent, it is preferable to use (B) a copolymerizable monomer containing a hydroxyl group. The preferred monomer composition of the copolymer is one or more of the above (A) and the above (B), and one or more of the above (A), the above (B) and the above (C), respectively. One or more of each of A), the above (B) and the above (G), and one or more of the above (A), the above (B), the above (C) and (G), and the like can be mentioned.

The pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition has an adhesive force of 0.05 to 0.1 N / 25 mm at a low-speed peeling speed of 0.3 m / min and a high-speed peeling speed of 30 m / min. The adhesive strength is preferably 1.0 N / 25 mm or less. As a result, it is possible to obtain a performance in which the adhesive strength does not change much depending on the peeling speed, and it is possible to quickly peel even by high-speed peeling. Further, since it is reattached, even when the surface protective film is once peeled off, it does not require an excessive force and can be easily peeled off from the adherend.

It is preferable that the surface resistivity of the pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition is 5.0 × 10 ⁺¹² Ω / □ or less, and the peeling band voltage is “± 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 large, the performance to release the static electricity generated by charging during peeling is inferior. Therefore, by making the surface resistivity sufficiently small, the peeling that occurs due to the static electricity generated when the adherend peels off the adhesive layer. The band voltage is reduced, and it is possible to suppress the influence on the electric control circuit of the adherend.

The gel fraction of the pressure-sensitive adhesive layer (the pressure-sensitive adhesive after cross-linking) formed by cross-linking the pressure-sensitive adhesive composition of the present invention is preferably 95 to 100%. Due to such a high gel fraction, the adhesive force does not become excessive at a low peeling rate, the elution of unpolymerized monomers or oligomers from the copolymer is reduced, and the reworkability and high temperature / high humidity are satisfied. Durability is improved and contamination of the adherend can be suppressed.

The pressure-sensitive adhesive film of the present invention is formed by forming a pressure-sensitive adhesive layer formed by cross-linking the pressure-sensitive adhesive composition of the present invention on one or both sides of a resin film. Further, the surface protective film of the present invention is a surface protective film formed by forming an adhesive layer formed by cross-linking the adhesive composition of the present invention on one side of a resin film. Since the pressure-sensitive adhesive composition of the present invention contains the above-mentioned components (A) to (F) in a well-balanced manner, it has excellent antistatic performance, and has a low peeling speed and a high peeling speed. It has an excellent balance of adhesive strength, and also has excellent durability and rework performance (there is no transfer of contamination to the adherend after tracing the surface protective film with a ballpoint pen through the adhesive layer). Become. Therefore, it can be suitably used as a surface protective film for a polarizing plate.

The thickness of the pressure-sensitive adhesive layer 2 used in the antistatic surface protective 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, for example. From the adherend, the pressure-sensitive adhesive layer 2 having a slight adhesive strength having a peeling strength (adhesive strength) of the antistatic surface protective film on the surface of the adherend of about 0.03 to 0.3 N / 25 mm is determined from the adherend. It is preferable because it has excellent operability when the antistatic surface protective film is peeled off. Further, since the release film 5 is excellent in operability when the release film 5 is peeled from the antistatic surface protective film 10, the release force of the release film 5 from the pressure-sensitive adhesive layer 2 is preferably 0.2 N / 50 mm or less.

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

Examples of the resin film 3 include a polyester film, a polyamide film, a polyethylene film, a polypropylene film, and a polyimide film, but the polyester film is particularly preferable because of its excellent transparency and relatively low price. .. The resin film may be a non-stretched film or a uniaxially or biaxially stretched film. Further, the draw ratio of the stretched film and the orientation angle of the axial method formed by crystallization of the stretched film may be controlled to a specific value.
The thickness of the resin film 3 is not particularly limited, but is preferably about 12 to 100 μm, and more preferably about 20 to 50 μm because it is easy to handle.
Further, if necessary, the surface of the resin film 3 may be subjected to an easy-adhesion treatment such as surface modification by corona discharge or application of an anchor coating agent.

Examples of the release agent containing dimethylpolysiloxane as a main component constituting the release agent layer 4 include known silicone-based release agents such as addition reaction type, condensation reaction type, cationic polymerization type, and radical polymerization type. Products commercially available as addition reaction type silicone release agents include, for example, KS-776A, KS-847T, KS-779H, KS-837, KS-778, 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 Toray Dow Corning Co., Ltd.) and the like. Examples of products commercially available as a condensation reaction type include SRX-290 and SYLOFF-23 (manufactured by Toray Dow Corning Co., Ltd.). Products commercially available as cationically polymerized types include, for example, TPR-6501, TPR-6500, UV9300, VU9315, UV9430 (manufactured by Momentive Performance Materials), X62-7622 (manufactured by Shin-Etsu Chemical Co., Ltd.). ) And so on. Examples of products commercially available as a radical polymerization type include X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.).

Examples of the silicone-based compound that is liquid at 20 ° C. constituting 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 on the surface of the pressure-sensitive adhesive layer, a silicone-based compound that is liquid at 20 ° C. in a state of being compatible with the release agent layer containing dimethylpolysiloxane as a main component is used. Be done. Among the modified silicone compounds, polyether-modified silicone is preferable for the application of the present invention. The polyether chain in the polyether-modified silicone is composed of ethylene oxide, propylene oxide, etc. For example, by selecting the molecular weight of the polyethylene oxide used for the side chain, physical properties such as compatibility with the silicone release agent and antistatic effect can be obtained. Is adjusted.
In addition, products commercially available as polyether-modified silicone 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 Toray Dow Corning Co., Ltd.), 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 Big Chemie) and the like.
The amount of the silicone compound added, which is liquid at 20 ° C. to the release agent containing dimethylpolysiloxane as the main component, varies depending on the type of the silicone compound and the degree of compatibility with the release agent, but an antistatic surface protective film is adhered. The setting may be made in consideration of the desired peeling band voltage, the contaminating property to the adherend, the adhesive property, and the like when peeling from the film.

The antistatic agent constituting the release agent layer 4 has good dispersibility in a release agent solution containing dimethylpolysiloxane as a main component and inhibits curing of the release agent containing dimethylpolysiloxane as a main component. Those that do not are preferable. Alkali metal salts are suitable as such antistatic agents.

Examples of the alkali metal salt include metal salts composed of lithium, sodium and potassium. Specifically, for example, cations composed of ^{Li +} , Na ⁺ and K ^{+ , 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 ⁻ A metal salt composed of an anion composed of the above is preferably used. Among them, especially 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 is 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 the antistatic agent added to the release agent containing dimethylpolysiloxane as the main component varies depending on the type of the antistatic agent and the degree of affinity with the release agent, but when the antistatic surface protective film is peeled off from the adherend. However, it may be set in consideration of the desired peeling band voltage, stain resistance to the adherend, adhesive properties, and the like.

The method of mixing the release agent containing dimethylpolysiloxane as a main component with the polyether-modified silicone and the antistatic agent is not particularly limited. A method of adding a polyether-modified silicone and an antistatic agent to a release agent containing dimethylpolysiloxane as a main component, mixing the mixture, and then adding and mixing a catalyst for curing the release agent. Removal using dimethylpolysiloxane as a main component. A method of diluting the agent with an organic solvent in advance and then adding and mixing a polyether-modified silicone and an antioxidant and a catalyst for curing the release agent. A release agent containing siloxane as a main component is diluted with an organic solvent in advance, and then the catalyst is used. Any method may be used, such as a method of adding and mixing the mixture, and then adding and mixing the polyether-modified silicone and the antistatic agent. Further, if necessary, an adhesion improver such as a silane coupling agent or a material that assists the antistatic effect such as a compound containing a polyoxyalkylene group may be added.

The mixing ratio of the release agent containing dimethylpolysiloxane as a main component, the polyether-modified silicone and the antistatic agent is not particularly limited, but with respect to the solid content 100 of the release agent containing dimethylpolysiloxane as a main component, The solid content of the polyether-modified silicone and the antistatic agent is preferably about 5 to 100. When the amount of the polyether-modified silicone and the antistatic agent added in terms of solid content is less than 5 with respect to the solid content of 100 of the release agent containing dimethylpolysiloxane as a main component, antistatic on the surface of the pressure-sensitive adhesive layer is prevented. The transfer amount of the agent is also reduced, and it becomes difficult for the adhesive to exert the antistatic function. Further, when the addition amount of the polyether-modified silicone and the antistatic agent in terms of solid content exceeds 100 with respect to the solid content of 100 of the release agent containing dimethylpolysiloxane as a main component, the polyether-modified silicone and the antistatic agent are prevented from being charged. Along with the agent, a release agent containing dimethylpolysiloxane as a main component is also transferred to the surface of the pressure-sensitive adhesive layer, which may reduce the pressure-sensitive adhesive properties of the pressure-sensitive adhesive.

The method of forming the pressure-sensitive adhesive layer 2 and the method of attaching the release film 5 to the base film 1 of the antistatic surface protective film 10 according to the present invention may be performed by a known method and is not particularly limited. Specifically, (1) a method in which a resin composition for forming an adhesive layer 2 is applied to one side of a base film 1, dried to form an adhesive layer, and then a release film 5 is attached. (2) A method of applying and drying a resin composition for forming the pressure-sensitive adhesive layer 2 on the surface of the release film 5 to form the pressure-sensitive adhesive layer, and then laminating the base film 1 and the like can be mentioned. Any method may be used.

Further, the pressure-sensitive 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, Mayer 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 cross-sectional view showing a state in which the release film is peeled off from the antistatic surface protective film of the present invention.
By peeling the release film 5 from the antistatic surface protective film 10 shown in FIG. 1, the silicone-based compound and the antistatic agent (reference numeral 7) liquid at 20 ° C. contained in the release agent layer 4 of the release film 5 A part is transferred (adhered) to the surface of the pressure-sensitive adhesive layer 2 of the antistatic surface protective film 10. Therefore, in FIG. 2, the silicone-based compound and the antistatic agent, which are liquid at 20 ° C. and transferred to the surface of the pressure-sensitive adhesive layer 2 of the antistatic surface protective film, are schematically shown by the spots of reference numeral 7.
In the antistatic surface protective film according to the present invention, when the antistatic surface protective film 11 in the state where the release film shown in FIG. 2 is peeled off is attached to the adherend, it is transferred to the surface of the pressure-sensitive adhesive layer 2. In addition, the liquid silicone compound and antistatic agent come into contact with the surface of the adherend at 20 ° C. As a result, when the antistatic surface protective film is peeled off from the adherend again, the peeling band voltage can be suppressed to a low level.

FIG. 3 is a cross-sectional view showing an embodiment of the optical component of the present invention.
The release film 5 is peeled off from the antistatic surface protective film 10 of the present invention, and the pressure-sensitive adhesive layer 2 is exposed and attached to the optical component 8 which is an adherend via the pressure-sensitive adhesive layer 2. To.
That is, FIG. 3 shows the optical component 20 to which the antistatic surface protective film 10 of the present invention is attached. Examples of the optical component include an optical film such as a polarizing plate, a retardation plate, a lens film, a polarizing plate that also serves as a retardation plate, and a polarizing plate that also serves as a lens film. Such optical components are used as constituent members of liquid crystal display devices such as liquid crystal display panels and various instruments such as optical system devices. Further, examples of the optical component include an optical film such as an antireflection film, a hard coat film, and a transparent conductive film for a touch panel. In particular, the prevention of optical films such as low-reflection treated polarizing plates (LR polarizing plates) and anti-glare low-reflection treated polarizing plates (AG-LR polarizing plates) whose surfaces are antifouling treated with silicone compounds or fluorine compounds. It can be suitably used as an antistatic surface protective film to be attached to a contaminated surface.
According to the optical component of the present invention, when the antistatic surface protective film 10 is peeled off and removed from the optical component (optical film) which is an adherend, the peeling band voltage can be suppressed sufficiently low, so that the driver There is no risk of damaging circuit components such as ICs, TFT elements, and gate wire drive circuits, and production efficiency in the process of manufacturing liquid crystal display panels and the like can be improved, and reliability of the production process can be maintained.

Next, the present invention will be further described with reference to Examples.

<Manufacturing of adhesive composition>
[Example 1]
Nitrogen gas was introduced into a reactor equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen introduction pipe, and the air in the reactor was replaced with nitrogen gas. Then, 60 parts by weight of a solvent (ethyl acetate) was added to the reaction apparatus together with 100 parts by weight of 2-ethylhexyl acrylate and 5.0 parts by weight of 8-hydroxyoctyl acrylate. Then, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise over 2 hours and reacted at 65 ° C. for 6 hours to obtain an acrylic copolymer solution of Example 1 having 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, and then 2.0 parts by weight of coronate HX (isocyanurate compound of hexamethylene diisocyanate compound) and 0.1 weight by weight of titanium trisacetylacetonate were added. The parts were added and mixed with stirring to obtain the pressure-sensitive adhesive composition of Example 1.

[Examples 2 to 6 and Comparative Examples 1 to 3]
The pressure-sensitive adhesive compositions of Examples 2 to 6 and Comparative Examples 1 to 3 are the same as those of Example 1 except that the composition of the pressure-sensitive adhesive composition of Example 1 is as shown in Tables 1 and 2, respectively. I got something. In Tables 1 and 2, the monomers contained (copolymerized) in the acrylic copolymer are (A), (B), (C), (G), and "carboxyl group-containing monomer".

Tables 1 and 2 are two separate tables showing the compounding ratio of each component, and in each case, the numerical value of the weight part obtained by assuming that the total of the group (A) is 100 parts by weight is enclosed in parentheses. Indicated by. The compound names of the abbreviations of the respective components used in Tables 1 and 2 are shown in Tables 3 and 4. Coronate (registered trademark) HX, HL and L are trade names of Nippon Polyurethane Industry Co., Ltd., and Takenate (registered trademark) D-140N, D-127N and D-110N are trade names of Mitsui Chemicals Co., Ltd. Is.

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

<Preparation of antistatic surface protection film>
[Example 1]
Additive reaction type silicone (manufactured by Toray Dow Corning Co., Ltd., product name: SRX-345) 5 parts by weight, polyether-modified silicone (manufactured by Toray Dow Corning Co., Ltd., product name: SH8400) 0.15 parts by weight, perchlorate 5 parts by weight of lithium 10% 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 platinum catalyst (manufactured by Toray Dow Corning Co., Ltd., product name: SRX-212 catalyst) Was mixed, stirred and mixed to prepare a coating material forming the release agent layer of Example 1. The paint forming the release agent layer of Example 1 is applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm with a mayer bar so that the thickness after drying becomes 0.2 μm, and a hot air circulation oven at 120 ° C. The film was dried for 1 minute to obtain a release film of Example 1.
The pressure-sensitive adhesive composition of Example 1 was applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm so as to have a thickness of 20 μm after drying, and then dried in a hot air circulation oven at 100 ° C. for 2 minutes. Formed a pressure-sensitive adhesive layer. Then, the release agent layer (silicone-treated surface) of the release film of Example 1 prepared above was bonded to the surface of the pressure-sensitive adhesive layer. The obtained adhesive film was kept warm in an environment of 40 ° C. for 5 days to cure the adhesive to obtain an antistatic surface protective film of Example 1.

[Examples 2 to 6]
An antistatic surface protective film of Examples 2 to 6 was obtained in the same manner as in Example 1 except that each of the pressure-sensitive adhesive compositions of Example 1 was made into the pressure-sensitive adhesive compositions of Examples 2 to 6.

[Comparative Example 1]
Addition reaction type silicone (manufactured by Toray Dow Corning Co., Ltd., product name: SRX-345) 5 parts by weight, 95 parts by weight of a 1: 1 mixed solvent of toluene and ethyl acetate, and platinum catalyst (manufactured by Toray Dow Corning Co., Ltd.) , Product name: SRX-212 catalyst) 0.05 parts by weight were mixed, stirred and mixed to prepare a coating material forming the release agent layer of Comparative Example 1. On the surface of a polyethylene terephthalate film having a thickness of 38 μm, a paint for forming a release agent layer of Comparative Example 1 is applied with a mayer bar so that the thickness after drying becomes 0.2 μm, and a hot air circulation type oven at 120 ° C. The film was dried for 1 minute to obtain a release film of Comparative Example 1.
The pressure-sensitive adhesive composition of Comparative Example 1 was applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm so as to have a thickness of 20 μm after drying, and then dried in a hot air circulation oven at 100 ° C. for 2 minutes. Formed a pressure-sensitive adhesive layer. Then, the release agent layer (silicone-treated surface) of the release film of Comparative Example 1 prepared above was bonded to the surface of the pressure-sensitive adhesive layer. The obtained adhesive film was kept warm in an environment of 40 ° C. for 5 days to cure the adhesive to obtain an antistatic surface protective film of Comparative Example 1.

[Comparative Example 2]
An antistatic surface protective film of Comparative Example 2 was obtained in the same manner as in Comparative Example 1 except that the pressure-sensitive adhesive composition of Comparative Example 1 was changed to the pressure-sensitive adhesive composition of Comparative Example 2.

[Comparative Example 3]
An antistatic surface protective film of Comparative Example 3 was obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive composition of Example 1 was changed to the pressure-sensitive adhesive composition of Comparative Example 3.

Table 7 shows the composition and thickness of the release agent layer in the antistatic surface protective films of Examples 1 to 6 and Comparative Examples 1 to 3.

<Test method and evaluation>
The surface protective films of Examples 1 to 6 and Comparative Examples 1 to 3 were aged at 23 ° C. and 50% RH for 7 days, and then the release film (silicone resin coated PET film) was peeled off to adhere. The exposed agent layer was used as a sample for measuring the surface resistivity.
Further, the surface protective film on which the pressure-sensitive adhesive layer is exposed is attached to the surface of the polarizing plate attached to the liquid crystal cell via the pressure-sensitive adhesive layer, left for 1 day, and then at 50 ° C., 5 atm, for 20 minutes. The sample which was autoclaved and left at room temperature for another 12 hours was used as a measurement sample of adhesive strength, peeling band voltage, and reworkability.

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

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

<Peeling band voltage>
High-precision electrostatic sensors SK-035 and SK-200 (stocks) can be used to measure the voltage (voltage band) generated by charging the polarizing plate when the measurement sample obtained above is peeled 180 ° at a tensile speed of 30 m / min. It was measured using (manufactured by the company Keyence), and the maximum value of the measured value was taken as the peeling band voltage.

<Reworkability>
After tracing the surface protective film of the measurement sample obtained above with a ball pen (load 500 g, 3 reciprocations), the surface protective film is peeled off from the polarizing plate, the surface of the polarizing plate is observed, and the polarizing plate is contaminated. It was confirmed that there was no migration. The evaluation target criteria are "○" when there is no contamination transfer on the polarizing plate, "△" when contamination transfer is confirmed at least in part along the trajectory traced with the ballpoint pen, and along the trajectory traced with the ballpoint pen. When the transfer of contamination was confirmed and the detachment of the adhesive was confirmed from the surface of the adhesive, it was evaluated as "x".

Table 8 shows the evaluation results. The surface resistivity is expressed by a method in which "m × 10 ^{+ n} " is set to "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 protective films of Examples 1 to 6 according to the present invention have appropriate adhesive strength, are not contaminated on the surface of the adherend, and when the antistatic surface protective film is peeled off from the adherend. The peeling band voltage is low.
On the other hand, the antistatic surface protective film of Comparative Example 1 in which a silicone compound and an antistatic agent are added to the pressure-sensitive adhesive layer has a good low surface resistivity of the pressure-sensitive adhesive layer, but has a high adhesive strength, so that the peeling band voltage is high. It was expensive and inferior in reworkability. Further, in Comparative Example 2, probably because the amount of the cross-linking accelerator added was large, the adhesive gelled and could not be applied. Further, in Comparative Example 3, since the monomer containing a carboxyl group was contained, the adhesive strength was large and the reworkability was slightly inferior.
That is, in Comparative Examples 1 and 2 in which the silicone compound and the antistatic agent are mixed in the pressure-sensitive adhesive, it is difficult to achieve both reduction of the peeling zone voltage and contamination of the adherend. On the other hand, in Examples 1 to 6 in which the silicone compound and the antistatic agent were added to the release agent layer and then the silicone compound and the antistatic agent were transferred to the surface of the pressure-sensitive adhesive layer, the release zone voltage was applied with a small amount of addition. A good antistatic surface protective film was obtained without contamination of the adherend.

The antistatic surface protective film of the present invention is, for example, an optical film such as a polarizing plate, a retardation plate, a lens film for a display, and the surface of the optical component in a production process of various other optical components. Can be used to protect. In particular, when it is used as an antistatic surface protective film for an optical film such as an LR polarizing plate or an AG-LR polarizing plate whose surface is antifouling treated with a silicone compound or a fluorine compound, it is peeled off from the adherend. When doing so, the amount of static electricity generated can be reduced.
The antistatic surface protective film of the present invention has less contamination on the adherend and has excellent peeling antistatic performance without deterioration over time, so that the yield in the production process can be improved, and its industrial utility value. Is large.

1 ... Base film, 2 ... Adhesive layer, 3 ... Resin film, 4 ... Release agent layer, 5 ... Release film, Silicone compound and antistatic agent liquid at 7 ... 20 ° C., 8 ... Adhesive (optical) Parts), 10 ... Antistatic surface protective film, 11 ... Antistatic surface protective film from which the release film has been peeled off, 20 ... Optical parts to which the antistatic surface protective film has been attached.

Claims (2)

For an antistatic surface protective film in which an adhesive layer is formed on one side of a base film made of a transparent resin, and an antistatic agent can be transferred to the surface of the adhesive layer. It ’s a release film,
The release film for an antistatic surface protective 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 is a release agent containing dimethylpolysiloxane as a main component. It is formed of a polyether-modified silicone which is a liquid silicone-based compound at 20 ° C. and a resin composition containing an alkali metal salt as the antistatic agent.
The pressure-sensitive adhesive layer is formed by cross-linking a pressure-sensitive adhesive composition containing an acrylic polymer, a cross-linking agent, a cross-linking accelerator, and a keto-enol tautomer compound.
Copolymerization in which the acrylic polymer contains (B) a hydroxyl group as a group of monomers copolymerizable with at least one (meth) acrylic acid ester monomer having (A) alkyl groups having C4 to C18 carbon atoms. Copolymerization of a possible monomer, (C) a nitrogen-containing vinyl monomer containing no hydroxyl group or an alkoxy group-containing alkyl (meth) acrylate monomer, and at least one selected from a copolymerizable monomer group consisting of (C) a copolymer. It is an acrylic polymer that has been made to
The cross-linking accelerator is at least one selected from the group consisting of an aluminum chelate compound, a titanium chelate compound, and an iron chelate compound.
The inside of the pressure-sensitive adhesive layer does not contain an antistatic agent and
The release agent layer contains the polyether-modified silicone and the alkali metal salt in a proportion of 5 to 100 parts by weight as a solid content with respect to 100 parts by weight of the solid content of the release agent containing dimethylpolysiloxane as a main component. ,
After the release film for the antistatic surface protective film is attached to the surface of the pressure-sensitive adhesive layer via the release agent layer, the release film for the antistatic surface protection film is peeled off from the surface of the pressure-sensitive adhesive layer. A release film for an antistatic surface protective film, characterized in that the polyether-modified silicone contained in the release agent layer and the alkali metal salt can be transferred only to the surface of the pressure-sensitive adhesive layer. The antistatic surface protective film according to claim 1, wherein the release film for the antistatic surface protective film is laminated.

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