JP6720388B2 - Method for producing antistatic surface protection film - Google Patents

Description

The present invention relates to an adhesive composition and a surface protective film. More specifically, it 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 has little stain resistance to an adherend and has excellent antistatic property for peeling without deterioration with time, and an antistatic surface protective film.

When manufacturing and transporting optical films such as polarizing plates, retardation films, lens films for displays, antireflection films, hard coat films, transparent conductive films for touch panels, and displays using the same. Has a surface protective film attached to 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 carried out with the surface protective film attached to the optical film in order to remove the surface protective film and to increase the work efficiency by eliminating the work of attaching again.
BACKGROUND ART Conventionally, a surface protective film having a pressure-sensitive adhesive layer provided on one surface of a base film has been generally used in the manufacturing process of optical products to prevent adhesion of scratches and stains. The surface protection film is attached to the optical film via a pressure-sensitive adhesive layer having a slight adhesive force. The pressure-sensitive adhesive layer has a slight adhesive strength because it can be easily peeled off when the used surface protective film is peeled off from the surface of the optical film and the pressure-sensitive adhesive is an adherend. This is to prevent it from adhering to and remaining on the optical film (so-called adhesive residue is prevented from occurring).

In recent years, in the production process of a liquid crystal display panel, the surface protection film laminated on the optical film, by a peeling electrification voltage generated when peeling and removing, for controlling the display screen of the liquid crystal display panel, The phenomenon that circuit components such as driver ICs are destroyed and the orientation of liquid crystal molecules is damaged occurs even though the number of occurrences is small.
Further, in order to reduce the power consumption of the liquid crystal display panel, the driving voltage of the liquid crystal material is becoming lower, and along with this, the breakdown voltage of the driver IC is also becoming lower. Recently, it has been required to set the peeling electrification voltage within a range of +0.7 kV to -0.7 kV.
Therefore, when the surface protective film is peeled off from the adherend optical film, the pressure-sensitive adhesive layer containing an antistatic agent for suppressing the peeling electrification voltage to be low in order to prevent a defect due to the high electrification electrification voltage. A surface protection film using is 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 polyisocyanate.
Further, Patent Document 2 discloses a pressure-sensitive adhesive composition made 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 comprising 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 disclose that a polyether-modified silicone is mixed in the pressure-sensitive adhesive layer of the surface protective film.

JP, 2005-131957, A JP, 2005-330464, A JP, 2005-314476, A JP, 2006-152235, A JP, 2009-275128, A Japanese Patent No. 4537450

In the above Patent Documents 1 to 4, the antistatic agent is added to the inside of the pressure-sensitive adhesive layer, but as the thickness of the pressure-sensitive adhesive layer becomes thicker, and as the elapsed time passes, the surface protection film is laminated. The amount of the antistatic agent that migrates from the pressure-sensitive adhesive layer to the adherend is larger than that of the adherend. Further, in an optical film such as an LR (Low Reflective) polarizing plate or an AG (Anti Glare)-LR polarizing plate, the surface of the optical film is treated with a silicone compound or a fluorine compound to prevent contamination. The peeling electrification voltage at the time of peeling the surface protection film used for such an optical film from the adherend optical film becomes high.

Further, when the polyether-modified silicone is mixed in the pressure-sensitive adhesive layer described in Patent Documents 5 and 6, it is difficult to finely adjust the adhesive force 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 formed with the surface protective film is The surface characteristics change subtly. Further, from the viewpoint of protecting the surface of the optical film, the thickness of the pressure-sensitive adhesive layer cannot be extremely reduced. Therefore, depending on the thickness of the pressure-sensitive adhesive layer, it is necessary to increase the addition amount of the polyether-modified silicone mixed in the pressure-sensitive adhesive layer, and as a result, the surface of the adherend is easily contaminated, and the adhesive force with time or Contamination to the adherend changes.

2. Description of the Related Art With the recent spread of 3D displays (stereoscopic displays), there has been an FPR (Film Patterned Retarder) film laminated on the surface of an optical film such as a polarizing plate. The FPR film is attached after the surface protection film attached to the surface of the optical film such as the polarizing plate is peeled off. However, if the surface of an optical film such as a polarizing plate is contaminated with the pressure-sensitive adhesive or antistatic agent used in the surface protective film, there is a problem that the FPR film is difficult to adhere. Therefore, the surface protection film used for the purpose is required to have little contamination on the adherend.

On the other hand, some liquid crystal panel manufacturers used the method of evaluating the stain resistance of the surface protection film to the adherend by peeling off the surface protection film attached to the optical film such as a polarizing plate once and allowing air bubbles to enter. A method of observing the surface of the adherend by peeling off the surface protection film and then heat-treating the re-bonded product in the above state under predetermined conditions is adopted. In such an evaluation method, even if the surface contamination of the adherend is small, the difference in the surface contamination of the adherend between the part in which the air bubbles are mixed and the part in which the adhesive of the surface protective film is in contact If there is, it remains as a trace of bubbles (sometimes called bubble jimi). Therefore, the method of evaluating the contamination of the surface of the adherend is a very strict evaluation method. In recent years, there has been a demand for a surface protective film that does not have a problem of contamination on the surface of an adherend even if the result of the judgment by such a strict evaluation method is used. However, it has been difficult to solve the problem with the surface protection film using a pressure-sensitive adhesive layer containing an antistatic agent, which has been conventionally proposed.

For this reason, there is a need for a surface protective film used for an optical film, which has very little contamination on an adherend and whose contamination property on the adherend does not change with time. Further, there is a demand for a surface protective film that suppresses the peeling electrification voltage when peeling from an adherend.

The present inventors diligently studied to solve this problem.
In order to reduce the contamination on the adherend and the change in antistatic performance over time, it is necessary to reduce the amount of the antistatic agent added, which is presumed to cause the contamination of the adherend. However, when the amount of the antistatic agent added is reduced, the peeling electrification voltage becomes high when the surface protective film is peeled from the adherend. The present inventors have studied a method of suppressing the peeling electrification voltage at the time of peeling the surface protective film from the adherend without increasing the absolute amount of the antistatic agent added. As a result, in the pressure-sensitive adhesive composition, an antistatic agent is not added and mixed to form a pressure-sensitive adhesive layer, but the pressure-sensitive adhesive composition is applied and dried to form a pressure-sensitive adhesive layer, and then the pressure-sensitive adhesive is laminated. The present invention found that the release electrification voltage can be suppressed low when the surface protective film is peeled from the adherend optical film by applying an appropriate amount of the antistatic agent component to the surface of the layer, Was completed.

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

In order to solve the above problems, the antistatic surface protective film of the present invention is a liquid at a suitable 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 applying the silicone compound and the antistatic agent as described above, the technical idea is to suppress the contamination property to the adherend to a low level and to suppress the peeling electrification voltage at the time of peeling from the optical film as the adherend to a low level. There is.

In order to solve the above-mentioned problems, the present invention comprises an adhesive layer formed on one surface of a substrate film made of a resin having transparency, and an antistatic agent transferred to the surface of the adhesive layer. A method for producing an antistatic surface protection film, wherein the pressure-sensitive adhesive layer comprises an acrylic polymer, (D) a difunctional or higher functional isocyanate compound, (E) a crosslinking accelerator, and (F) ketoenol tautomerism. Body compound, and a pressure-sensitive adhesive layer obtained by crosslinking a pressure-sensitive adhesive composition containing the acrylic polymer, wherein the acrylic polymer is at least a (meth)acrylic acid ester monomer having (A) an alkyl group carbon number of C4 to C18. From one type, as a copolymerizable monomer group, (B) a hydroxyl group-containing copolymerizable monomer, and (C) a hydroxyl group-free nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth)acrylate monomer. Which is an acrylic polymer obtained by copolymerizing at least one selected from the group of copolymerizable monomers, wherein the ratio of the (F) ketoenol tautomer compound to the (E) crosslinking accelerator is , (E):(F) in a weight ratio of 1:80 to 1:500, and a release agent layer containing an antistatic agent is laminated on one surface of the resin film, and the release agent layer is dimethyl. A release film formed of a resin composition containing a release agent containing polysiloxane as a main component, a silicone-based compound that is liquid at 20° C., and an antistatic agent, and the pressure-sensitive adhesive layer via the release agent layer. Of the release agent, after peeling the release film from the surface of the pressure-sensitive adhesive layer, to transfer only the surface of the pressure-sensitive adhesive layer, the silicone compound and the antistatic agent of the release agent layer. A method for producing a characteristic antistatic surface protective film is provided.

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

The (E) crosslinking accelerator is preferably at least one selected from the group consisting of aluminum chelate compounds, titanium chelate compounds, and iron chelate compounds.

In addition, the copolymerizable monomer having a hydroxyl group (B) is 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth). ) At least one selected from the group of compounds 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. In addition, it is preferable that at least one 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 and a diol compound, and is a diisocyanate compound. Is an aliphatic diisocyanate, one selected from the group of compounds consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, 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, consisting of one selected from the group of compounds, trifunctional isocyanate compound As the isocyanurate body of hexamethylene diisocyanate compound, isocyanurate body of isophorone diisocyanate compound, adduct body of hexamethylene diisocyanate compound, adduct body of isophorone diisocyanate compound, burette body of hexamethylene diisocyanate compound, burette body of isophorone diisocyanate compound, Isocyanurate body of tolylene diisocyanate compound, isocyanurate body of xylylene diisocyanate compound, isocyanurate body of hydrogenated xylylene diisocyanate compound, adduct body of tolylene diisocyanate compound, adduct body of xylylene diisocyanate compound, hydrogenated xylylene diisocyanate It is preferably composed of an adduct of the compound.

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

Further, the silicone compound in the release agent layer is preferably a polyether-modified silicone.

The antistatic agent in the release agent layer is preferably an alkali metal salt.

Moreover, in order to solve the above-mentioned subject, this invention has the number of carbon atoms of (A) alkyl group of C4-C18 (meth)acrylic acid ester monomer on one side of the base material film which consists of resin which has transparency. At least one kind, and a copolymerizable monomer group containing no carboxyl group-containing copolymerizable monomer, but (B) a hydroxyl group-containing copolymerizable monomer and (C) a hydroxyl group-free nitrogen. Acrylic system comprising a copolymer obtained by copolymerizing at least one selected from the group of copolymerizable monomers consisting of a vinyl monomer containing or an alkoxy group-containing alkyl (meth)acrylate monomer containing no hydroxyl 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 keto-enol tautomer compound. A release film formed by laminating a release agent layer containing an antistatic agent on one surface of a resin film on the surface of the pressure-sensitive adhesive layer, the release agent layer being laminated via the release agent layer, the release agent The layer is formed of a resin composition containing a release agent containing dimethylpolysiloxane as a main component, a silicone-based compound that is liquid at 20° C., and an antistatic agent. The layer is formed only on the surface of the pressure-sensitive adhesive layer. The silicone compound and the antistatic agent of the release agent layer are transferred, and the weight of (E):(F) as the ratio of the (F) ketoenol tautomer compound to the (E) crosslinking accelerator. Provided is an antistatic surface protective film, characterized in that the ratio is 1:80 to 1:500.

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

Further, the silicone compound in the release agent layer is preferably a polyether-modified silicone.

The antistatic agent in the release agent layer is preferably an alkali metal salt.

The present invention also provides an optical film obtained by laminating the above antistatic surface protective film.

The present invention also provides an optical component obtained by laminating the above antistatic surface protective film.

The antistatic surface protective film of the present invention has little stain on the adherend, and its low stain resistance on the adherend does not change with time. Further, according to the present invention, even if the surface of an adherend such as an LR polarizing plate or an AG-LR polarizing plate is an optical film which is antifouling-treated with a silicone compound or a fluorine compound, the antistatic property is prevented. It is possible to suppress the peeling electrification voltage generated when the surface protective film is peeled from the adherend, and to provide an antistatic surface protective film having excellent peeling antistatic performance without deterioration over time.
According to the antistatic surface protection film of the present invention, the surface of the optical film can be reliably protected, so that the productivity and the 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 the peeling film from the antistatic surface protection film of this invention. It is sectional drawing which showed one of the 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 sectional view showing the concept of an antistatic surface protective 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 having a release agent layer 4 formed on the surface of a resin film 3 is attached 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 resin having transparency and flexibility is used. Thereby, the appearance inspection of the optical component can be performed in a state where the antistatic surface protection film is attached 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 the polyester film, a film made of other resin can be used as long as it has necessary strength and optical suitability. The base film 1 may be a non-stretched film or a uniaxially or biaxially stretched film. Moreover, you may control the draw ratio of a stretched film and the orientation angle of the axial method formed with crystallization of a stretched film to a specific value.
The thickness of the substrate film 1 used for the antistatic surface protection film 10 according to the present invention 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 easy to handle. , And more preferable.
If necessary, an antifouling layer for preventing surface stains, an antistatic layer, a scratch-resistant hard coat layer, etc. may be 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 substrate film 1 may be subjected to an easy adhesion treatment such as surface modification by corona discharge or application of an anchor coating agent.

The pressure-sensitive adhesive layer 2 used in the antistatic surface protective film 10 according to the present invention is a pressure-sensitive adhesive that adheres to the surface of an adherend and can be easily peeled off after use and does not easily contaminate the adherend. It is not particularly limited as long as it is, but it is common to use an acrylic pressure-sensitive adhesive obtained by crosslinking a (meth)acrylate copolymer in consideration of durability after bonding to an optical film. ..

In particular, the main component of the acrylic pressure-sensitive adhesive is a copolymer containing a carboxyl group as a copolymerizable monomer group with at least one (A) alkyl group (A) alkyl group (C4 to C18) (meth)acrylic acid ester monomer. Copolymerization that does not contain a polymerizable monomer, but comprises (B) a hydroxyl group-containing copolymerizable monomer and (C) a hydroxyl group-free nitrogen-containing vinyl monomer or alkoxy group-containing alkyl (meth)acrylate monomer. A pressure-sensitive adhesive layer made of an acrylic polymer that is a copolymer of at least one selected from the 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 a pressure-sensitive adhesive composition containing (D) a bifunctional or higher functional isocyanate compound, (E) a crosslinking accelerator, and (F) a ketoenol tautomer compound in addition to the acrylic polymer. A drug layer is preferred.

Examples of the (meth)acrylic acid ester monomer having (A) an alkyl group having a C4 to C18 carbon number include butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, and 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) Examples thereof include acrylate, isomyristyl (meth)acrylate, cetyl (meth)acrylate, isocetyl (meth)acrylate, stearyl (meth)acrylate, and isostearyl (meth)acrylate.
When the total amount of the acrylic polymer of the copolymer is 100 parts by weight, the (A) alkyl group contains a C4 to C18 (meth)acrylic acid ester monomer in a proportion of 50 to 95 parts by weight. Is preferred.

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

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

Among (C), examples of the (C-1) nitrogen-containing vinyl monomer include a vinyl monomer having an amide bond, a vinyl monomer having 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 pyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N-vinyllaurylolactam; N-( (Meth)acryloylmorpholine, N-(meth)acryloylpiperazine, N-(meth)acryloylaziridine, N-(meth)acryloylazetidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylpiperidine, N-(meth) ) Acyclic nitrogen vinyl compounds having an N-(meth)acryloyl-substituted heterocyclic structure such as acryloylazepan and N-(meth)acryloylazocan; nitrogen atoms such as N-cyclohexylmaleimide and N-phenylmaleimide; 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, Nt-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 (Meth)acrylate, N,N-dimethylaminobutyl (meth)acrylate, N,N-diethylaminomethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N-ethyl-N-methylaminoethyl (meth ) Acrylate, N-methyl-N-propylaminoethyl (meth)acrylate, N-methyl-N-isopropylaminoethyl (meth) A) acrylate, dialkylamino(meth)acrylates such as 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, diacetone acrylamide, N,N -(Meth)acrylamides such as methylenebis(meth)acrylamide; unsaturated carboxylic acid nitriles such as (meth)acrylonitrile; and the like.

As the (C-1) nitrogen-containing vinyl monomer, those not containing a hydroxyl group are preferable, and those not containing a hydroxyl group and a carboxyl group are more preferable. Examples of such a monomer include the above-exemplified monomers, for example, an acrylic monomer containing an N,N-dialkyl-substituted amino group or an N,N-dialkyl-substituted amide group; 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 preferable.

Among (C), as the (C-2) alkoxy group-containing alkyl (meth)acrylate monomer, 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, 3-butoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, 4-ethoxybutyl (meth)acrylate, 4-propoxybutyl (meth)acrylate, 4-isopropoxybutyl (meth)acrylate, 4- Butoxy butyl (meth)acrylate etc. are 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 polymer of the copolymer is 100 parts by weight, 0 to 20 parts by weight of the (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 ratio of parts. The nitrogen-containing vinyl monomer containing no (C-1) hydroxyl group and the alkyl (meth)acrylate monomer containing (C-2) alkoxy group may be used alone or in combination of two or more kinds. In the pressure-sensitive adhesive layer according to the present invention, the pressure-sensitive adhesive composition may not contain (C) a hydroxyl group-free nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth)acrylate monomer.

The (D) difunctional or higher functional isocyanate compound may be at least one or two or more selected from polyisocyanate compounds having at least two isocyanate (NCO) groups in one molecule. The polyisocyanate compound is classified into an aliphatic isocyanate, an aromatic isocyanate, an acyclic isocyanate, an alicyclic isocyanate, 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). , Hydrogenated xylylene diisocyanate (H6XDI), dimethyldiphenylene diisocyanate (TOID), tolylene diisocyanate (TDI), and other aromatic isocyanate compounds.
Examples of the trifunctional or higher isocyanate compound include a bifunctional isocyanate compound (compound having two NCO groups in one molecule), a buret modified product, an isocyanurate modified product, trimethylolpropane (TMP), glycerin, or the like having a valence of 3 or more. And the polyol (compound having at least 3 or more OH groups in one molecule) of 1).
It is also possible to use only (D-1) a trifunctional isocyanate compound or (D-2) a bifunctional isocyanate compound as the (D) bifunctional or higher functional 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 body of a hexamethylene diisocyanate compound, an isocyanurate body of an isophorone diisocyanate compound, an adduct body of a hexamethylene diisocyanate compound, an adduct body of an isophorone diisocyanate compound, At least one or more 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 body, isocyanurate body of xylylene diisocyanate compound, isocyanurate body of hydrogenated xylylene diisocyanate compound, adduct body of tolylene diisocyanate compound, adduct body of xylylene diisocyanate compound, adduct body of hydrogenated xylylene diisocyanate compound And (D-1-2) at least one selected from the second aromatic isocyanate compound group. 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 or more selected from the group of the (D-1-1) first aliphatic isocyanate compound and (D-1-2) ) By using in combination with at least one or more selected from the second aromatic isocyanate compound group, it is possible to further improve the balance of the adhesive strength in the low-speed peeling region and the high-speed peeling region.

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

Further, the (D-2) difunctional isocyanate compound used in the present invention is preferably an acyclic aliphatic isocyanate compound which is produced by reacting a diisocyanate compound and a diol compound.
For example, a diisocyanate compound is represented by the 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). When the diol compound is represented by ), examples of the compound produced by reacting the diisocyanate compound with the diol compound include compounds 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 of 0 or more. When n is 0, the general formula Z represents "O=C=N-X-N=C=O". As the bifunctional acyclic aliphatic isocyanate compound, a compound in which n is 0 in the general formula Z (a diisocyanate compound not reacted with the diol compound) may be contained, 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 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, aliphatic divalent group. The aliphatic diisocyanate is preferably composed of one or more selected from the 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, 2-ethyl-2. -Butyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol monohydroxypivalate, polyethylene glycol, polypropylene glycol It is preferable to be composed of one kind or two or more kinds selected.

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

The crosslinking accelerator (E) may be a substance which 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, and a tertiary amine Examples thereof include amine compounds, metal chelate compounds, organotin compounds, organolead compounds, organozinc compounds, and other organometallic compounds. In the present invention, a metal chelate compound or an organic tin compound is preferable as the crosslinking 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 monodentate ligand X bonded to the metal atom M. For example, when a 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 Ls may be the same ligand or 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 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 keto-enol tautomeric compounds, and in the polydentate ligand L, an enol deprotonated enolate (eg acetylacetonate) may be used.
Examples of the monodentate ligand X include halogen atoms such as chlorine atom and bromine atom, pentanoyl group, hexanoyl group, 2-ethylhexanoyl group, octanoyl group, nonanoyl group, decanoyl group, dodecanoyl group and octadecanoyl group. Examples thereof include alkoxy groups 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, titanium trisacetylacetonate, ruthenium trisacetylacetonate, zinc bisacetylacetonate, and aluminum tris. Acetylacetonate, zirconium tetrakisacetylacetonate, tris(2,4-hexanedionate)iron(III), bis(2,4-hexanedionato)zinc, tris(2,4-hexanedionato)titanium, tris Examples include (2,4-hexanedionate)aluminum and tetrakis(2,4-hexanedionate)zirconium.

Examples of the organotin compound include dialkyltin oxide, fatty acid salt of dialkyltin, and fatty acid salt of stannous tin. Conventionally, many dibutyltin compounds have been used, but in recent years, the toxicity problem of organotin compounds has been pointed out, and tributyltin (TBT) contained in dibutyltin compounds has been feared as an endocrine disrupting substance. From the viewpoint of safety, long-chain alkyltin compounds such as dioctyltin compounds are preferable. Specific examples of the organic tin compound include dioctyl tin oxide and dioctyl tin dilaurate. Temporarily, Sn compounds can also be used, but in view of the trend of requiring the use of substances with higher safety in the future, such as Al, Ti, Fe, etc., which have higher safety than Sn, can be used. It is preferable to use a metal chelate compound.
The (E) crosslinking accelerator in the pressure-sensitive adhesive composition according to the present invention is preferably at least one selected from the group consisting of aluminum chelate compounds, titanium chelate compounds, and iron chelate compounds.
The crosslinking accelerator (E) is preferably contained in an amount of 0.001 to 0.5 part by weight based on 100 parts by weight of the copolymer.

Examples of the (F) keto-enol tautomer compound include β-keto esters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate and stearyl acetoacetate, acetylacetone, and 2,4-hexanedione. , Β-diketones such as benzoylacetone. These are, in a pressure-sensitive adhesive composition using a polyisocyanate compound as a cross-linking agent, by blocking the isocyanate group of the cross-linking agent, to suppress excessive viscosity increase and gelation of the pressure-sensitive adhesive composition after the incorporation of the cross-linking agent. The pot life of the pressure-sensitive adhesive composition can be extended.
The (F) 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.

Since the (F) ketoenol tautomeric compound has an effect of suppressing crosslinking, contrary to the (E) crosslinking accelerator, the ratio of the (F) ketoenol tautomeric compound to the (E) crosslinking accelerator. Is preferably set appropriately. In order to increase 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, and most preferably 1:80 to 1:500.

The acrylic polymer may further contain (G) a 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 of the plural 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 base polymer. The other hydroxyl group may be OH as it is, or may be an alkyl ether such as methyl ether or ethyl ether, or a saturated carboxylic acid ester such as acetic acid ester.
Examples of the alkylene group contained in the polyalkylene glycol include, but are not limited to, an ethylene group, a propylene group, a 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 the polyalkylene glycol copolymer 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.
The (G) polyalkylene glycol mono(meth)acrylic acid ester monomer preferably has an average number of repeating alkylene oxides constituting the polyalkylene glycol chain of 3 to 14. The “average number of repeating alkylene oxides” is the average number of repeating alkylene oxide units in the “polyalkylene glycol chain” portion contained in the molecular structure of the (G) polyalkylene glycol mono(meth)acrylic acid ester monomer. is there.

(G) The 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. It is preferably at least one kind.
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; methoxy polyethylene glycol-(meth)acrylate, methoxy polypropylene 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. are mentioned.
When the total amount of the acrylic polymer of the copolymer is 100 parts by weight, it is preferable to contain the (G) polyalkylene glycol mono(meth)acrylic acid ester monomer in a proportion 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 (H) a polyether-modified siloxane compound. (H) a polyether-modified siloxane compound is a siloxane compound having a polyether group, in addition to the normal siloxane units [-SiR ¹ ₂ -O-], siloxane units having polyether groups [-SiR ¹ (R having _{^{2 O (R 3 O) n}} R 4) -O- ]. Here, R ¹ is one or more kinds of alkyl groups or aryl groups, R ² and R ³ are one or more kinds of alkylene groups, and R ⁴ is one or more kinds of 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 ].

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 the (H) polyether-modified siloxane compound is contained in an amount of 0.01 to 1.0 part by weight based on 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 in JIS K3211, (surfactant term), for example.

The (H) polyether-modified siloxane compound can be obtained by, for example, grafting an organic compound having an unsaturated bond and a polyoxyalkylene group onto a polyorganosiloxane main chain having a silicon hydride group by a hydrosilylation reaction. it can. Specifically, dimethyl siloxane/methyl (polyoxyethylene) siloxane copolymer, dimethyl siloxane/methyl (polyoxyethylene) siloxane/methyl (polyoxypropylene) siloxane copolymer, dimethyl siloxane/methyl (polyoxypropylene) Examples thereof include siloxane polymers.
By blending the (H) polyether-modified siloxane compound in the pressure-sensitive adhesive composition, the pressure-sensitive adhesive strength and rework performance of the pressure-sensitive adhesive can be improved. When the pressure-sensitive adhesive composition does not contain the polyether-modified siloxane compound, the cost becomes 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 blended. These may be used alone or in combination of two or more.

The copolymer of the main component used in the pressure-sensitive adhesive composition of the present invention is a monomer group that is copolymerizable with at least one (A) alkyl group (C)-C18 (meth)acrylate monomer. It is selected from the group of copolymerizable monomers consisting of (B) a hydroxyl group-containing copolymerizable monomer and (C) a hydroxyl group-free nitrogen-containing vinyl monomer or alkoxy group-containing alkyl (meth)acrylate monomer. It can be synthesized by copolymerizing at least one of these. The copolymerizable monomer group may further include (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: (D) a bifunctional or higher functional isocyanate compound, (E) a cross-linking accelerator, (F) a ketoenol tautomer compound, and an optional additive in addition to the above copolymer. 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, or (meth)acrylamide.
Since the acrylic polymer does not contain a carboxyl group-containing copolymerizable monomer as a copolymerizable monomer group, it is effective in improving the crosslinking rate and stabilizing the adhesive force. It is preferable to use (B) a hydroxyl group-containing copolymerizable monomer as the monomer that reacts with the (D) bifunctional or higher functional isocyanate compound used as a crosslinking agent. As a preferable monomer composition of the copolymer, one or more each of the (A) and the (B), one or more each of the (A), the (B) and the (C), and the ( One or more kinds each from A), the above (B) and the above (G), one or more kinds each from the above (A), the above (B), the above (C) and (G), and the like.

The pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition has an adhesive force of 0.05 to 0.1 N/25 mm at a low peeling speed of 0.3 m/min and a high 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 is less changed by the peeling speed, and the peeling can be performed quickly even by the high speed peeling. Further, since the film is reattached, even when the surface protection film is once peeled off, it does not require an excessive force and can be easily peeled off from the adherend.

The pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition preferably has a surface resistivity of 5.0×10 ⁺¹² Ω/□ or less and a peeling electrification 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 large, the performance to dissipate static electricity generated by electrification at the time of peeling is inferior, so by making the surface resistivity sufficiently small, peeling caused by static electricity generated when peeling the adhesive layer from the adherend The electrification voltage is reduced, and it is possible to suppress the influence on the electrical control circuit and the like of the adherend.

The pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition of the present invention (pressure-sensitive adhesive after crosslinking) preferably has a gel fraction of 95 to 100%. Due to such a high gel fraction, the adhesive force does not become excessive at a low peeling speed, the elution of unpolymerized monomer or oligomer from the copolymer is reduced, and reworkability and high temperature and high humidity are reduced. The durability is improved, and contamination of the adherend can be suppressed.

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

Although 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, for example, a thickness of about 5 to 40 μm is preferable, and a thickness of about 10 to 30 μm is more preferable. From the adherend, the antistatic surface protective film is a pressure-sensitive adhesive layer 2 having a peel strength (adhesive strength) of about 0.03 to 0.3 N/25 mm with respect to the surface of the adherend. It is preferable because it is excellent in operability when peeling off the antistatic surface protective film. Further, the peeling force of the peeling film 5 from the pressure-sensitive adhesive layer 2 is preferably 0.2 N/50 mm or less because the operability when peeling the peeling film 5 from the antistatic surface protection film 10 is excellent.

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

Examples of the resin film 3 include a polyester film, a polyamide film, a polyethylene film, a polypropylene film, a polyimide film, and the like. However, 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. Moreover, you may control the draw ratio of a stretched film and the orientation angle of the axial method formed with crystallization of a stretched film to a specific value.
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 easier to handle and more preferable.
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 that constitutes 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. Commercially available products 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 commercially available products of the condensation reaction type include SRX-290 and SYLOFF-23 (manufactured by Toray Dow Corning Co., Ltd.). Examples of commercially available products of the cationic polymerization type include TPR-6501, TPR-6500, UV9300, VU9315, UV9430 (manufactured by Momentive Performance Materials Co., Ltd.), X62-7622 (manufactured by Shin-Etsu Chemical Co., Ltd.). ) And the like. Examples of commercially available products of 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, carbinol higher fatty acid ester-modified silicone, and the like. In the present invention, in order to improve the antistatic property of the surface of the pressure-sensitive adhesive layer, a silicone-based compound which is liquid at 20° C. in a state of being compatible with the release agent layer containing dimethylpolysiloxane as a main component is used. To be Among the modified silicone compounds, polyether-modified silicone is preferred for use in 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 polyethylene oxide used for the side chain, the physical properties such as compatibility with the silicone release agent and antistatic effect. 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 can be mentioned.
The amount of the silicone compound that is liquid at 20° C. with respect to the release agent containing dimethylpolysiloxane as a main component varies depending on the type of the silicone compound and the degree of compatibility with the release agent. It may be set in consideration of a desired peeling electrification voltage, a stain resistance to an adherend, an adhesive property, and the like when peeling from.

The antistatic agent forming 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 preferred. As such an antistatic agent, an alkali metal salt is suitable.

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 ⁺ and Cl ⁻ , Br ⁻ , I ⁻ and BF _{4 are used. ^{-, 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 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 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 the antistatic agent added to the release agent containing dimethylpolysiloxane as a main component depends on the type of the antistatic agent and the degree of affinity with the release agent, but when the antistatic surface protective film is released from the adherend. It may be set in consideration of desired peeling electrification voltage, stain resistance to adherend, adhesive property and the like.

There is no particular limitation on the method of mixing the release agent containing dimethylpolysiloxane as the main component with 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 containing dimethylpolysiloxane as a main component, and after mixing, a catalyst for curing the release agent is added and mixed, and a release agent containing dimethylpolysiloxane as a main component is added. The agent is diluted with an organic solvent in advance, and then a polyether-modified silicone and an antistatic agent and a catalyst for curing the release agent are added and mixed, and the release agent containing siloxane as a main component is diluted with the organic solvent in advance and then the catalyst is added. May be added and mixed, and then the polyether modified silicone and the antistatic agent may be added and mixed. Further, if necessary, an adhesion improver such as a silane coupling agent or a material such as a compound containing a polyoxyalkylene group, which assists the antistatic effect, 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 the solid content of the release agent containing dimethylpolysiloxane as a main component is 100: The proportion of the polyether-modified silicone and the antistatic agent as solids is preferably about 5 to 100. If the addition amount of the polyether-modified silicone and the antistatic agent in terms of solid content is less than 5 relative to 100 of the solid content of the release agent containing dimethylpolysiloxane as the main component, the antistatic property of the surface of the pressure-sensitive adhesive layer is prevented. The transfer amount of the agent also decreases, and it becomes difficult for the pressure-sensitive adhesive to exert its 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 100 of the solid content of the release agent containing dimethylpolysiloxane as a main component, the polyether-modified silicone and the antistatic agent are added. The release agent containing dimethylpolysiloxane as a main component together with the agent is also transferred to the surface of the pressure-sensitive adhesive layer, which may reduce the adhesive property of the pressure-sensitive adhesive.

The method for forming the pressure-sensitive adhesive layer 2 and the method for laminating the release film 5 on the base film 1 of the antistatic surface protective film 10 according to the present invention may be performed by known methods and are not particularly limited. Specifically, (1) a method of applying a resin composition for forming the pressure-sensitive adhesive layer 2 on one surface of the base film 1, drying the pressure-sensitive adhesive layer to form the pressure-sensitive adhesive layer, and then laminating the release film 5 thereon, (2) A method of coating the resin composition for forming the pressure-sensitive adhesive layer 2 on the surface of the release film 5 and drying the resin composition to form the pressure-sensitive adhesive layer, and then laminating the base film 1 may be mentioned. Either method may be used.

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, 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 where the release film is peeled off from the antistatic surface protection film of the present invention.
By peeling off the release film 5 from the antistatic surface protective film 10 shown in FIG. 1, the liquid silicone compound and the antistatic agent (reference numeral 7) contained in the release agent layer 4 of the release film 5 at 20° C. A part is transferred (attached) to the surface of the pressure-sensitive 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 are transferred to the surface of the pressure-sensitive adhesive layer 2 of the antistatic surface protective film, are schematically shown by the spots 7.
In the antistatic surface protective film according to the present invention, the antistatic surface protective film 11 in the state where the release film shown in FIG. 2 is peeled off is transferred to the surface of the pressure-sensitive adhesive layer 2 when it is attached to an adherend. Further, the silicone compound and the antistatic agent which are liquid at 20° C. come into contact with the surface of the adherend. Thereby, the peeling electrification voltage at the time of peeling the antistatic surface protective film from the adherend again can be suppressed to be 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 the pressure-sensitive adhesive layer 2 is exposed, and the pressure-sensitive adhesive layer 2 is stuck to the optical component 8 as an adherend. It
That is, FIG. 3 shows an optical component 20 to which the antistatic surface protection film 10 of the present invention is attached. Examples of the optical component include optical films such as a polarizing plate, a retardation plate, a lens film, a polarizing plate also serving as a retardation plate, and a polarizing plate also serving as a lens film. Such an optical component is used as a constituent member of a liquid crystal display device such as a liquid crystal display panel, various instruments, and an optical system device. Examples of the optical component also include optical films such as antireflection films, hard coat films, and transparent conductive films for touch panels. In particular, the surface of an optical film such as a low-reflection treated polarizing plate (LR polarizing plate) or an anti-glare low-reflection treated polarizing plate (AG-LR polarizing plate) whose surface is treated to prevent contamination with a silicone compound, a fluorine compound, etc. It can be suitably used as an antistatic surface protective film that is attached to the surface subjected to the contamination treatment.
According to the optical component of the present invention, when the antistatic surface protective film 10 is peeled and removed from the optical component (optical film) that is the adherend, the peeling electrification voltage can be suppressed to a sufficiently low level. There is no risk of damaging circuit components such as ICs, TFT elements, gate line drive circuits, etc., and production efficiency in the process of manufacturing a liquid crystal display panel or 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.

<Production of adhesive composition>
[Example 1]
Nitrogen gas was introduced into a reactor equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet tube, 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 reactor together with 100 parts by weight of 2-ethylhexyl acrylate and 5.0 parts by weight of 8-hydroxyoctyl acrylate. Then, 0.1 parts 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 of hexamethylene diisocyanate compound) and 0.1 parts by weight of titanium trisacetylacetonate. Parts were added and mixed by stirring to obtain an 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 were prepared in the same manner as in Example 1 except that the compositions of the pressure-sensitive adhesive composition of Example 1 were as described in Table 1 and Table 2, respectively. I got a thing. 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 an integrated table showing the compounding ratio of each component divided into two. In each case, the numerical value of the weight part obtained by taking the total of the (A) group as 100 parts by weight is enclosed in parentheses. Indicate. Further, the compound names of the abbreviations of the 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., Takenate (registered trademark) D-140N, D-127N and D-110N are trade names of Mitsui Chemicals, Inc. Is.

<Synthesis of bifunctional isocyanate compound>
The bifunctional isocyanate compounds of Synthesis Examples 1 and 2 were synthesized by the following method. As shown in Table 5 and Table 6, the diisocyanate and the diol compound were mixed in a molar ratio of NCO/OH=16 and reacted at 120° C. for 3 hours, and thereafter, using a thin film evaporator under reduced pressure. 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 type silicone (manufactured by Toray Dow Corning, product name: SRX-345), 0.15 part by weight of polyether-modified silicone (manufactured by Toray Dow Corning, product name: SH8400), perchloric acid 5 parts by weight of a 10% ethyl acetate solution of lithium, 95 parts by weight of a mixed solvent of 1:1 of toluene and ethyl acetate, and 0.05 parts by weight of a platinum catalyst (manufactured by Toray Dow Corning Co., Ltd., product name: SRX-212 Catalyst). Were mixed, stirred and mixed to prepare a coating material for forming the release agent layer of Example 1. On the surface of a polyethylene terephthalate film having a thickness of 38 μm, the coating material for forming the release agent layer of Example 1 was applied by a Mayer bar so that the thickness after drying was 0.2 μm, and the hot air circulating oven at 120° C. And dried for 1 minute to obtain a release film of Example 1.
The pressure-sensitive adhesive composition of Example 1 was applied onto the surface of a polyethylene terephthalate film having a thickness of 38 μm so that the thickness after drying would be 20 μm, and then dried in a hot air circulation oven at 100° C. for 2 minutes. To form an adhesive layer. After that, the release agent layer (silicone-treated surface) of the release film of Example 1 produced above was attached to the surface of this pressure-sensitive adhesive layer. The obtained pressure-sensitive adhesive film was kept warm at 40° C. for 5 days to cure the pressure-sensitive adhesive, and the antistatic surface protective film of Example 1 was obtained.

[Examples 2 to 6]
Antistatic surface protective films of Examples 2 to 6 were obtained in the same manner as in Example 1 except that the pressure sensitive adhesive compositions of Example 1 were changed to the pressure sensitive adhesive compositions of Examples 2 to 6, respectively.

[Comparative Example 1]
5 parts by weight of addition reaction type silicone (manufactured by Toray Dow Corning, product name: SRX-345), 95 parts by weight of a mixed solvent of toluene and ethyl acetate of 1:1 and platinum catalyst (manufactured by Toray Dow Corning) (Product name: SRX-212 Catalyst) 0.05 part by weight was mixed and stirred to mix 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, the coating material for forming the release agent layer of Comparative Example 1 was applied with a Mayer bar so that the thickness after drying was 0.2 μm, and the hot air circulating oven at 120° C. And 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 that the thickness after drying would be 20 μm, and then dried in a hot air circulation oven at 100° C. for 2 minutes. To form an adhesive layer. After that, the release agent layer (silicone-treated surface) of the release film of Comparative Example 1 produced above was attached to the surface of this pressure-sensitive adhesive layer. The obtained pressure-sensitive adhesive film was kept warm in an environment of 40° C. for 5 days to cure the pressure-sensitive adhesive and 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 Comparative Example 1 except that the adhesive composition of Comparative Example 1 was changed to the 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 protection films in Examples 1 to 6 and Comparative Examples 1 to 3 were aged in an atmosphere of 23° C. and 50% RH for 7 days, and then the release film (a PET film coated with a silicone resin) was peeled off to give an adhesive property. The exposed surface of the agent layer was used as a surface resistivity measurement sample.
Further, the surface protective film showing this pressure-sensitive adhesive layer was bonded to the surface of the polarizing plate bonded to the liquid crystal cell via the pressure-sensitive adhesive layer, and left for 1 day, then, at 50° C., 5 atmospheric pressure, 20 minutes. An autoclave-treated sample, which was left at room temperature for 12 hours, was used as a sample for measuring adhesive strength, peeling electrification voltage, and reworkability.

<Adhesive strength>
The measurement sample (having a surface protective film with a width of 25 mm attached to the surface of a polarizing plate) obtained above was used in a 180° direction using a tensile tester to give a low peeling speed (0.3 m/min) and a high speed. Was peeled at a peeling speed (30 m/min), and the peel strength measured was taken as the adhesive strength.

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

<Peeling electrification voltage>
The voltage (charge voltage) generated when the polarizing plate was charged when the measurement sample obtained above was peeled 180° at a pulling speed of 30 m/min was measured using high-precision electrostatic sensors SK-035, SK-200 (stock (Manufactured by KEYENCE CORPORATION), and the maximum measured value was defined as the peeling electrification voltage.

<Reworkability>
After tracing the surface protection film of the measurement sample obtained above with a ballpoint pen (load 500 g, 3 reciprocations), peel the surface protection film from the polarizing plate, observe the surface of the polarizing plate, and contaminate the polarizing plate. I confirmed that there was no migration. The evaluation target criteria are "○" when there is no contamination transfer on the polarizing plate, "△" when at least a part of contamination transfer is confirmed along the trajectory traced by the ballpoint pen, and along the trajectory traced by the ballpoint pen. The case where the transfer of contamination was confirmed and the release of the adhesive from the adhesive surface was also confirmed 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).

The measurement results shown in Table 8 show the following.
The antistatic surface protective films of Examples 1 to 6 according to the present invention have appropriate adhesive strength, no contamination on the surface of the adherend, and the antistatic surface protective film when peeled from the adherend. The peeling electrification voltage is low.
On the other hand, the antistatic surface protective film of Comparative Example 1 in which the silicone compound and the antistatic agent were added to the pressure-sensitive adhesive layer was good in that the surface resistivity of the pressure-sensitive adhesive layer was low, but the peeling electrification voltage was It was high and inferior in reworkability. In Comparative Example 2, the adhesive gelled and the coating could not be performed, probably because the amount of the crosslinking accelerator added was large. Further, in Comparative Example 3, since the monomer containing the carboxyl group was included, 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 peeling electrification 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 electrification voltage was small. As a result, there was no contamination on the adherend and a good antistatic surface protective film was obtained.

The antistatic surface protective film of the present invention is, for example, a film for optical use such as a polarizing plate, a retardation plate, a lens film for a display, and the like, in the production process of various optical parts and the like, the surface of the optical parts and the like. 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 treated to prevent contamination 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.
INDUSTRIAL APPLICABILITY The antistatic surface protective film of the present invention can improve the yield of the production process because it has less stains on the adherend and further has excellent antistatic property for peeling without deterioration over time, and has an industrial utility value. Is large.

DESCRIPTION OF SYMBOLS 1... Base material film, 2... Adhesive layer, 3... Resin film, 4... Release agent layer, 5... Release film, 7... Silicone compound and antistatic agent which are liquid at 20 degreeC, 8... Adhesive (optical Parts) 10... Antistatic surface protective film, 11... Antistatic surface protective film with peeling film peeled off, 20... Optical component with laminated antistatic surface protective film.

Claims (2)

A method for producing an antistatic surface protective film, comprising a pressure-sensitive adhesive layer formed on one surface of a substrate film made of a resin having transparency, and an antistatic agent transferred to the surface of the pressure-sensitive adhesive layer. ,
The pressure-sensitive adhesive layer cross-links a pressure-sensitive adhesive composition containing an acrylic polymer, (D) a bifunctional or higher functional isocyanate compound, (E) a crosslinking accelerator, and (F) a ketoenol tautomer compound. It is a pressure-sensitive adhesive layer,
A copolymer in which the acrylic polymer (A) has a hydroxyl group (B) as a monomer group that is copolymerizable with at least one kind of a (meth)acrylic acid ester monomer having a C4 to C18 alkyl group. Copolymerizable monomer with at least one selected from the group of copolymerizable monomers consisting of (C) a hydroxyl group-free nitrogen-containing vinyl monomer or an alkoxy group-containing alkyl (meth)acrylate monomer. Is an acrylic polymer,
The (E) crosslinking accelerator is a metal chelate compound,
As a ratio of the (F) ketoenol tautomer compound to the (E) crosslinking accelerator, the weight ratio of (E):(F) is 1:80 to 1:500,
A release agent layer containing an antistatic agent is laminated on one surface of a resin film, and the release agent layer contains a release agent containing dimethylpolysiloxane as a main component, a silicone-based compound that is liquid at 20° C. A release film formed of a resin composition containing an inhibitor, after bonding to the surface of the pressure-sensitive adhesive layer via the release agent layer, peel the release film from the surface of the pressure-sensitive adhesive layer, A method for producing an antistatic surface protective film, which comprises transferring the silicone compound and the antistatic agent of the release agent layer only to the surface of the pressure-sensitive adhesive layer. An antistatic surface protective film produced by the method for producing an antistatic surface protective film according to claim 1, which is attached to an optical component as an adherend via the pressure-sensitive adhesive layer. A method for manufacturing an optical component, which is obtained by laminating an anti-surface protective film.

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