JP7301178B2 - Antistatic surface protective film - Google Patents

Description

The present invention relates to an antistatic surface protective film. More specifically, it relates to a method for producing an antistatic surface protective film having antistatic performance, and an antistatic surface protective film, which causes less contamination on the adherend and has excellent peeling antistatic performance without deterioration over time. A method for producing an antistatic surface protective film and an antistatic surface protective film are provided.

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 to laminate a surface protective film on the surface of the optical film to prevent the surface from being soiled or scratched in the post-process. Appearance inspection of the optical film, which is a product, is sometimes performed while the surface protective film is laminated to the optical film in order to improve work efficiency by eliminating the need to remove the surface protective film and re-laminate it.
2. Description of the Related Art 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 optical products in order to prevent the adhesion of scratches and stains. The surface protective film is attached to the optical film via a slightly adhesive adhesive layer. The pressure-sensitive adhesive layer has a low 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 a product that is an adherend. This is to prevent the adhesive from adhering to and remaining on the optical film (preventing the occurrence of so-called adhesive residue).

In recent years, in the production process of liquid crystal display panels, the display screen of the liquid crystal display panel is controlled by the peeling electrification voltage generated when the surface protective film laminated on the optical film is peeled off and removed. Phenomena in which circuit components such as driver ICs are destroyed and phenomena in which the alignment of liquid crystal molecules is damaged have occurred, although the number of occurrences is small.
In addition, in order to reduce the power consumption of the liquid crystal display panel, the drive voltage of the liquid crystal material has been lowered, and along with this, the breakdown voltage of the driver IC has also been lowered. Recently, it has been demanded that the stripping electrification voltage be within the range of +0.7 kV to -0.7 kV.
Therefore, when the surface protective film is peeled off from the adherend optical film, in order to prevent problems caused by high peeling electrostatic voltage, an adhesive layer containing an antistatic agent for suppressing low peeling electrostatic voltage is provided. A surface protection film using

For example, Patent Literature 1 discloses a surface protection film using an 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 comprising 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-adsorptive compound, and a surface protective film using the composition.
Further, Patent Document 4 discloses an adhesive composition comprising an ionic liquid, an alkali metal salt, and a polymer having a glass transition temperature of 0° C. or less, and a surface protection film using the same.
Moreover, Patent Documents 5 and 6 show that a polyether-modified silicone is mixed in the pressure-sensitive adhesive layer of the surface protection film.

JP-A-2005-131957 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, an antistatic agent is added inside the pressure-sensitive adhesive layer. The amount of the antistatic agent that migrates from the pressure-sensitive adhesive layer to the adherend increases with respect to the adherend. In optical films such as LR (Low Reflective) polarizing plates and AG (Anti Glare)-LR polarizing plates, the surface of the optical film is anti-fouling treated with a silicone compound or fluorine compound. When the surface protective film used as an optical film is peeled off from the optical film as an adherend, the peeling electrification voltage becomes high.

Further, when the polyether-modified silicone is mixed in the adhesive layer as described in Patent Documents 5 and 6, it is difficult to finely adjust the adhesive force of the surface protective film. In addition, since polyether-modified silicone is mixed in the adhesive layer, if the conditions for coating and drying the adhesive composition on the base film change, the pressure-sensitive adhesive layer formed with the surface protection film will not change. Surface properties change subtly. Furthermore, 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, depending on the thickness of the adhesive layer, it is necessary to increase the amount of polyether-modified silicone to be mixed in the adhesive layer. Staining property to the adherend changes.

In recent years, with the popularization of 3D displays (stereoscopic displays), there is a type in which an FPR (Film Patterned Retarder) 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 the polarizing plate, the FPR film is attached. However, if the surface of an optical film such as a polarizing plate is contaminated with the adhesive or antistatic agent used in the surface protective film, there is a problem that the FPR film is difficult to adhere. For this reason, surface protection films used for such applications are required to cause less contamination to adherends.

On the other hand, in some liquid crystal panel manufacturers, as a method of evaluating the staining property of the surface protective film on the adherend, the surface protective film attached to the optical film such as the polarizing plate is once peeled off, and air bubbles are mixed. A method is adopted in which the adherend is re-bonded in a state of being stuck, heat-treated under predetermined conditions, then the surface protective film is peeled off, and the surface of the adherend is observed. In this evaluation method, even if the amount of surface contamination on the adherend is very small, the difference in surface contamination between the part where the air bubbles are mixed and the part where the pressure-sensitive adhesive of the surface protection film is in contact can be detected. If there is, it will remain as a trace of air bubbles (sometimes called bubble stains). Therefore, it is a very severe evaluation method as a method for evaluating the staining property on the surface of the adherend. In recent years, there has been a demand for a surface protective film that does not cause a problem of staining on the surface of adherends, even as a result of judgment by such a strict evaluation method. However, conventionally proposed surface protective films using an antistatic agent-containing pressure-sensitive adhesive layer are in a situation where it is difficult to solve the problem.

Therefore, there is a demand for a surface protective film for use in optical films that causes very little staining of adherends and does not change its staining properties over time. Furthermore, there is a demand for a surface protective film that has a low peeling electrification voltage when peeled from an adherend.

The inventors of the present invention have diligently studied how to solve this problem.
In order to reduce contamination of adherends and to reduce changes in antistatic performance over time, it is necessary to reduce the amount of the antistatic agent added, which is presumed to be the cause of contamination of adherends. However, when the amount of the antistatic agent added is reduced, the peeling electrification voltage increases when the surface protective film is peeled from the adherend. The present inventors have investigated a method for suppressing the peeling electrification voltage when the surface protective film is peeled from the adherend without increasing the absolute amount of the antistatic agent added. As a result, instead of adding an antistatic agent to the adhesive composition and mixing it to form an adhesive layer, the adhesive composition is coated and dried to laminate the adhesive layer, and then the adhesive The inventors have found that by adding an appropriate amount of an antistatic agent component to the surface of the layer, the peeling electrification voltage when the surface protective film is peeled off from the adherend, the optical film, can be kept low. completed.

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

In order to solve the above problems, the antistatic surface protection film of the present invention is obtained by coating and drying an adhesive composition, laminating an adhesive layer, and then adding an appropriate amount of an antistatic agent to the surface of the adhesive layer. The technical idea is to suppress the staining property to the adherend and to suppress the peeling electrification voltage at the time of peeling from the adherend, the optical film, to a low level.

In order to solve the above problems, the present invention provides a method for producing an antistatic surface protective film, comprising the following steps (1) to (3), step (1): a pressure-sensitive adhesive composition containing an acrylic polymer In the acrylic polymer, (A) a total of 100 parts by weight of a (meth)acrylic acid ester monomer having an alkyl group having a carbon number of C1 to C18, (a1) an alkyl group having a carbon number of C1 to 1 to 30 parts by weight of at least one C4 (meth)acrylic acid ester monomer, and (a2) at least one (meth)acrylic acid ester monomer in which the alkyl group has a carbon number of C5 to C18, and 70 to 99 parts by weight of at least one (meth)acrylic acid ester monomer. and 0.1 to 12 parts by weight of (B) at least one copolymerizable monomer containing a hydroxyl group as a group of copolymerizable monomers. The acrylic polymer does not contain a copolymerizable monomer containing a carboxyl group and a nitrogen-containing vinyl monomer that does not contain a hydroxyl group, and the pressure-sensitive adhesive composition further contains (C) a bifunctional or higher isocyanate compound , (D) a cross-linking accelerator, and (E) a ketoenol tautomer compound, a step of producing a pressure-sensitive adhesive composition, and a step (2): a base film made of a resin having transparency. Step (3): A release agent layer containing an antistatic agent is laminated on one side of a resin film on the surface of the pressure-sensitive adhesive layer. a step of laminating the separated release film via the release agent layer, and transferring the antistatic agent of the release agent layer to the surface of the pressure-sensitive adhesive layer; and steps (1) to (3). The release agent layer is formed of a resin composition containing a release agent containing dimethylpolysiloxane as a main component and an antistatic agent, and the pressure-sensitive adhesive layer is subjected to a low-reflection surface treatment. The pressure-sensitive adhesive layer has a peeling electrification voltage of ±0.6 kV or less when peeled after being bonded to the polarizing plate that has been subjected to the low-reflection surface treatment, and the pressure-sensitive adhesive layer is peeled after being bonded to the polarizing plate that has been subjected to the low-reflection surface treatment. Provided is a method for producing an antistatic surface protection film characterized by good staining resistance when washed.

Further, in the pressure-sensitive adhesive composition, (F) a polyalkylene glycol mono(F) having an average repeating number of 3 to 14 alkylene oxides constituting a polyalkylene glycol chain and a diester content in the monomer of 0.2% or less ( It preferably contains a meth)acrylate monomer.

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

Further, in order to solve the above problems, the present invention comprises a base film made of a resin having transparency, and a pressure-sensitive adhesive layer formed on one side of the base film by cross-linking a pressure-sensitive adhesive composition containing an acrylic polymer. An antistatic surface protective film in which a release film in which a release agent layer containing an antistatic agent is laminated on one side of a resin film on the surface of the pressure-sensitive adhesive layer is laminated via the release agent layer, , the acrylic polymer comprises (A) a total of 100 parts by weight of at least one (meth)acrylic acid ester monomer having an alkyl group having a carbon number of C1 to C18, and (B) a hydroxyl group-containing copolymerizable The acrylic polymer is a copolymer obtained by copolymerizing a total of 0.1 to 12 parts by weight of at least one or more monomers, and the (A) alkyl group has a carbon number of C1 to C18 (meta) Of the total 100 parts by weight of at least one or more acrylic acid ester monomers, the total of (a1) at least one (meth)acrylic acid ester monomer having an alkyl group with a carbon number of C1 to C4 is 1 to 30 parts by weight. , (a2) a total of at least one (meth)acrylic acid ester monomer having an alkyl group of C5 to C18 carbon atoms in a proportion of 70 to 99 parts by weight, and the acrylic polymer contains carboxyl A copolymerizable monomer containing a group and a nitrogen-containing vinyl monomer containing no hydroxyl group are not copolymerized, and the pressure-sensitive adhesive composition further comprises (C) a bifunctional or higher isocyanate compound, and (D) A release agent containing a cross-linking accelerator and (E) a ketoenol tautomer compound and containing no antistatic agent, wherein the release agent layer contains dimethylpolysiloxane as a main component and a resin composition containing polyether-modified silicone, which is a silicone compound that is liquid at 20 ° C., and an antistatic agent, and the release from the surface of the adhesive layer of the antistatic surface protective film When the film is peeled off, the antistatic agent of the release agent layer is transferred to the surface of the adhesive layer, and the antistatic surface protective film from which the release film is peeled off is attached to the surface via the adhesive layer. After bonding to a polarizing plate subjected to a low-reflection surface treatment as an adherent, when the pressure-sensitive adhesive layer is peeled off from the polarizing plate, the surface of the polarizing plate is visually observed to find no contamination. To provide an antistatic surface protective film.

Further, the pressure-sensitive adhesive composition further comprises (F) a polyalkylene glycol chain with respect to a total of 100 parts by weight of (A) a (meth)acrylic acid ester monomer having an alkyl group having a carbon number of C1 to C18 0 to 50 parts by weight of a polyalkylene glycol mono(meth)acrylic acid ester monomer having an average repeating number of alkylene oxide of 3 to 14 and a diester content in the monomer of 0.2% or less (however, even if it does not contain yes) preferably included.

The (D) 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, and the content thereof is 0.00 per 100 parts by weight of the acrylic polymer. 001 to 0.5 parts by weight, containing 0.1 to 300 parts by weight of the (E) ketoenol tautomer compound, and the ratio of (E)/(D) is 70 to 1000 parts by weight. Preferably.

In addition, the (B) copolymerizable monomer containing a hydroxyl group is 8-hydroxyoctyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (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, and the acrylic polymer It is preferably 0.1 to 10 parts by weight per 100 parts by weight.

Further, as the (C) bifunctional or higher isocyanate compound, the bifunctional isocyanate compound is an acyclic aliphatic isocyanate compound, which is a compound produced by reacting a diisocyanate compound and a diol compound, and as the diisocyanate compound is an aliphatic diisocyanate, one selected from the group of compounds consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate; 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 consisting of one selected from the group of compounds, trifunctional Examples of isocyanate compounds include isocyanurate compounds of hexamethylene diisocyanate compounds, isocyanurate compounds of isophorone diisocyanate compounds, adduct compounds of hexamethylene diisocyanate compounds, adduct compounds of isophorone diisocyanate compounds, burette compounds of hexamethylene diisocyanate compounds, and burette compounds 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 xyl An adduct of a diisocyanate compound, preferably 0.1 to 10 parts by weight per 100 parts by weight of the acrylic polymer.

Further, in the adhesive composition, a (H) polyether-modified siloxane compound having an HLB value of 7 to 15 is added to 1.0 parts by weight or less (0 parts by weight in the case of 0 parts by weight) with respect to 100 parts by weight of the acrylic polymer. except), preferably included.

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

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

Also, the antistatic agent in the release agent layer is a Li salt, preferably at least one selected from the compound group consisting of LiTFSI, LiFSI and LiTF.

The present invention also provides an optical film obtained by laminating the above antistatic surface protection film with the release film removed.

The present invention also provides an optical component formed by laminating the above antistatic surface protection film with the release film removed.

The antistatic surface protective film of the present invention causes little contamination to adherends, and the low contamination property to adherends does not change over time. Further, according to the present invention, even optical films, such as LR polarizing plates and AG-LR polarizing plates, on which the surface of the adherend is anti-fouling treated with a silicone compound, a fluorine compound, or the like, are antistatic. It is possible to provide an antistatic surface protective film that can suppress the peeling electrification voltage generated when the surface protective film is peeled from an adherend and has excellent peeling antistatic performance without deterioration over time.
According to the antistatic surface protection film of the present invention, since the surface of the optical film can be reliably protected, productivity and yield can be improved.

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

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on embodiments.
FIG. 1 is a cross-sectional view showing the concept of the antistatic surface protective film of the present invention. This antistatic surface protective film 10 has an adhesive layer 2 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 pressure-sensitive adhesive layer 2 .

As the base film 1 used for the antistatic surface protection film 10 according to the present invention, a base film made of a resin having transparency and flexibility is used. As a result, the appearance of the optical component can be inspected in a state where the antistatic surface protection film is adhered to the optical component as an adherend. Polyester films such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and polybutylene terephthalate are preferably used as the transparent resin film used as the base film 1 . In addition to the polyester film, films made of other resins can also be used as long as they have the required strength and optical suitability. The base film 1 may be an unstretched film or a uniaxially or biaxially stretched film. Moreover, the draw ratio of the stretched film and the orientation angle in the axial direction formed along with the crystallization of the stretched film may be controlled to specific values.
The thickness of the base film 1 used in the antistatic surface protective 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. , more preferred.
Further, if necessary, the surface of the base film 1 opposite to the surface on which the pressure-sensitive adhesive layer 2 is formed is provided with an antifouling layer, an antistatic layer, an anti-scratch hard coat layer, or the like to prevent the surface from being soiled. can be provided. In addition, the surface of the base film 1 may be subjected to surface modification by corona discharge, easy-adhesion treatment such as application of an anchor coating agent.

The pressure-sensitive adhesive layer 2 used in the antistatic surface protection film 10 according to the present invention is a pressure-sensitive adhesive that adheres to the surface of the adherend, can be easily removed after use, and does not easily stain the adherend. Although it is not particularly limited as long as it is used, it is preferable to use an acrylic pressure-sensitive adhesive obtained by cross-linking a pressure-sensitive adhesive composition containing an acrylic polymer in consideration of durability after lamination to an optical film. Common.

In particular, the acrylic polymer contains (A) a (meth)acrylic acid ester monomer having an alkyl group having a carbon number of C1 to C18, and (a1) a (meth)acrylic acid ester monomer having an alkyl group having a carbon number of C1 to C4. At least one type and (a2) at least one type of (meth)acrylic acid ester monomer having an alkyl group having a carbon number of C5 to C18, and as a group of copolymerizable monomers, (B) a hydroxyl group-containing copolymerizable A pressure-sensitive adhesive layer made of an acrylic polymer that is a copolymer obtained by copolymerizing at least one type of monomer is preferred.
The copolymerizable monomer group further includes (F) a polyalkylene glycol having an average repeating number of 3 to 14 alkylene oxides constituting a polyalkylene glycol chain and a diester content in the monomer of 0.2% or less. Mono (meth) acrylate monomers may be included.
The acrylic polymer preferably does not contain copolymerizable monomers containing carboxyl groups and nitrogen-containing vinyl monomers containing no hydroxyl groups.
Furthermore, in addition to the acrylic polymer, (C) a bifunctional or higher isocyanate compound, (D) a cross-linking accelerator, and (E) a ketoenol tautomer compound. Agent layers are preferred.

Among (A) (meth)acrylic acid ester monomers in which the alkyl group has C1 to C18 carbon atoms, at least one (a1) (meth)acrylic acid ester monomer in which the alkyl group has C1 to C4 carbon atoms is Butyl (meth)acrylate, isobutyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and isopropyl (meth)acrylate.
(a2) Examples of (meth)acrylic acid ester monomers in which the number of carbon atoms in the alkyl group is C5 to C18 include pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, myristyl (meth)acrylate, isomyristyl (meth)acrylate, cetyl ( meth)acrylate, isocetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, and the like.
(A) With respect to a total of 100 parts by weight of (meth)acrylic acid ester monomers having alkyl groups of C1 to C18 carbon atoms, (a1) (meth)acrylic acid ester monomers having alkyl groups of C1 to C4 carbon atoms 1 to 30 parts by weight of at least one and 70 to 99 parts by weight of (a2) at least one (meth)acrylic acid ester monomer having an alkyl group having a carbon number of C5 to C18. Preferably, at least one of (a1) is contained in a ratio of 5 to 25 parts by weight and at least one of (a2) is contained in a ratio of 75 to 95 parts by weight. It is particularly preferable to contain at least one of a1) in an amount of 8 to 22 parts by weight and at least one of (a2) in an amount of 78 to 92 parts by weight.

(B) Examples of copolymerizable monomers containing hydroxyl groups include 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. hydroxyalkyl (meth)acrylates such as , 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) ) is preferably at least one compound selected from the compound group consisting of acrylamide and N-hydroxyethyl (meth)acrylamide. These (B) hydroxyl group-containing copolymerizable monomers do not have polyalkylene glycol chains, unlike (F) polyalkylene glycol mono(meth)acrylic acid ester monomers described later.
(A) With respect to a total of 100 parts by weight of (meth)acrylic acid ester monomers in which the number of carbon atoms in the alkyl group is C1 to C18, (B) at least one copolymerizable monomer containing a hydroxyl group is added in an amount of 0.1 to Copolymerization is preferably carried out at a rate of 12 parts by weight, more preferably from 0.1 to 9.5 parts by weight, and particularly preferably from 0.3 to 8 parts by weight.
Further, when the total amount of the acrylic polymer is 100 parts by weight, it is preferable that the (B) hydroxyl group-containing copolymerizable monomer is contained in a proportion of 0.1 to 10 parts by weight. It is more preferably 1 to 8.5 parts by weight, particularly preferably 0.3 to 7.5 parts by weight.

(C) The difunctional or higher isocyanate compound may be at least one or two 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, and any of them may be used. Specific examples of polyisocyanate compounds 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), and tolylene diisocyanate (TDI).
Examples of trifunctional or higher isocyanate compounds include bifunctional isocyanate compounds (compounds having two NCO groups in one molecule) with burette modification and isocyanurate modification, trimethylolpropane (TMP), glycerin and the like. and an adduct (polyol modified product) with a polyol (compound having at least 3 or more OH groups in one molecule).
As the (C) difunctional or higher isocyanate compound, it is also possible to use (C-1) the trifunctional isocyanate compound alone or (C-2) the difunctional isocyanate compound alone. It is also possible to use (C-1) a trifunctional isocyanate compound and (C-2) a bifunctional isocyanate compound in combination.

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

In addition, (C-1) the trifunctional isocyanate compound comprises at least one selected from the group of (C-1-1) first aliphatic isocyanate compounds, and the (C-1- 2) 0.5 to 5.0 parts by weight in total with respect to 100 parts by weight of the acrylic polymer, including at least one selected from the second group of aromatic isocyanate compounds preferably included. (C-1-1) at least one selected from the first aliphatic isocyanate compound group and (C-1-2) the second aromatic isocyanate compound group The mixing ratio of at least one selected from among (C-1-1): (C-1-2) is in the range of 10%: 90% to 90%: 10% by weight Preferably.

Furthermore, the (C-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 in the general formula "O=C=N-X-N=C=O" (where X is a divalent group), the general formula "HO-Y-OH" (where Y is a divalent group ) represents the diol compound, examples of the compound produced by reacting the diisocyanate compound and 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 that has not reacted with the diol compound) may be included, but a compound in which n is an integer of 1 or more is an essential component. It is preferable to include as The difunctional acyclic aliphatic isocyanate compound may be a mixture of compounds in which n in the general formula Z is different.

A 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 one or more selected from the compound group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate.

A diol compound represented by the general formula “HO—Y—OH” is an aliphatic diol. Y is preferably an acyclic, 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 monohydroxy pivalate, polyethylene glycol, polypropylene glycol It is preferably composed of one or more selected types.

It is preferable that the weight ratio (C-1/C-2) of the trifunctional isocyanate compound (C-1) and the difunctional isocyanate compound (C-2) is 1-90. It is preferable that (C) the di- or higher functional isocyanate compound is 0.1 to 10 parts by weight with respect to 100 parts by weight of the acrylic polymer.

(D) The cross-linking accelerator may be any substance that functions as a catalyst for the reaction (cross-linking reaction) between the acrylic polymer and the cross-linking agent when a polyisocyanate compound is used as the cross-linking agent. amine compounds, metal chelate compounds, organic tin compounds, organic lead compounds, organic zinc compounds, and the like. In the present invention, a metal chelate compound or an organic tin compound is preferable as the cross-linking accelerator.

A metal chelate compound is a compound in which one or more polydentate ligands L are bonded to a central metal atom M. The metal chelate compound may or may not have one or more monodentate ligands X bound 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 different ligands. When n is 2 or more, n Xs may be the same ligand or different ligands.

Metal atoms M include Fe, Ni, Mn, Cr, V, Ti, Ru, Zn, Al, Zr, Sn and the like.
Examples of the multidentate 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), β-diketones such as 2,4-hexanedione and benzoylacetone. These are keto-enol tautomeric compounds, which in the polydentate ligand L may be deprotonated enolates of enols (eg acetylacetonate).
The monodentate ligand X includes halogen atoms such as chlorine and bromine atoms, acyloxy groups such as pentanoyl, hexanoyl, 2-ethylhexanoyl, octanoyl, nonanoyl, decanoyl, dodecanoyl and octadecanoyl group, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, alkoxy group such as butoxy group, and the like.

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

Examples of organic tin compounds include dialkyltin oxides, dialkyltin fatty acid salts, stannous fatty acid salts, and the like. Conventionally, many dibutyltin compounds have been used, but in recent years, the problem of toxicity of organic tin compounds has been pointed out, and especially tributyltin (TBT) contained in dibutyltin compounds is also a concern as an endocrine disrupting substance. From the viewpoint of safety, long-chain alkyltin compounds such as dioctyltin compounds are preferred. Specific examples of organic tin compounds include dioctyltin oxide and dioctyltin dilaurate. Sn compounds can also be used temporarily, but in the future, in view of the trend of demanding the use of safer substances, Al, Ti, Fe, etc., which are safer than Sn, can be used. It is preferred to use metal chelate compounds.
The cross-linking accelerator (D) 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.
(D) The cross-linking accelerator is preferably contained in an amount of 0.001 to 0.5 parts by weight with respect to 100 parts by weight of the acrylic polymer.

(E) Ketoenol tautomer compounds include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate, acetylacetone, and 2,4-hexanedione. , β-diketones such as benzoylacetone. These block the isocyanate group of the cross-linking agent in the pressure-sensitive adhesive composition using a polyisocyanate compound as a cross-linking agent, thereby suppressing excessive viscosity increase and gelation of the pressure-sensitive adhesive composition after the cross-linking agent is blended. , the pot life of the adhesive composition can be extended.
(E) The keto-enol tautomer compound is preferably contained in an amount of 0.1 to 300 parts by weight with respect to 100 parts by weight of the acrylic polymer.

(E) The keto-enol tautomer compound has the effect of suppressing cross-linking, contrary to the (D) cross-linking accelerator, so the ratio of the (E) keto-enol tautomer compound to the (D) cross-linking accelerator is preferably set appropriately. In order to prolong the pot life of the adhesive composition and improve the storage stability, the weight part ratio of (E)/(D) is preferably 70 to 1000, more preferably 70 to 700. , 80-600.

The acrylic polymer can optionally contain (F) a polyalkylene glycol mono(meth)acrylic acid ester monomer as the copolymerizable monomer group. The (F) polyalkylene glycol mono(meth)acrylic acid ester monomer may be a compound in which one hydroxyl group among a plurality of hydroxyl groups of polyalkylene glycol is esterified as a (meth)acrylic acid ester. Since the (meth)acrylate group becomes a polymerizable group, it can be copolymerized with the acrylic polymer. Other hydroxyl groups may be OH as they are, alkyl ethers such as methyl ether and ethyl ether, saturated carboxylic acid esters such as acetic acid esters, and the like.
The alkylene group possessed by the polyalkylene glycol includes, but is 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. Copolymers of polyalkylene glycol include polyethylene glycol-polypropylene glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, polyethylene glycol-polypropylene glycol-polybutylene glycol and the like. It may be a block copolymer or a random copolymer.
(F) The polyalkylene glycol mono(meth)acrylic acid ester monomer preferably has an average repeating number of 3 to 14 for the alkylene oxide constituting the polyalkylene glycol chain. The "average repeating number of alkylene oxide" is the average number of repeating alkylene oxide units in the "polyalkylene glycol chain" portion contained in the molecular structure of (F) polyalkylene glycol mono(meth)acrylate monomer. be.
(F) In the polyalkylene glycol mono(meth)acrylic acid ester monomer, the diester content in the monomer is preferably 0.2% or less. The "diester content in the monomer" is the content (% by weight) of the polyalkylene glycol di(meth)acrylate contained in the (F) polyalkylene glycol mono(meth)acrylate monomer.

(F) polyalkylene glycol mono(meth)acrylic acid ester monomer selected from polyalkylene glycol mono(meth)acrylate, methoxypolyalkyleneglycol (meth)acrylate, ethoxypolyalkyleneglycol (meth)acrylate, At least one or more is preferable.
More specifically, polyethylene glycol-mono (meth) acrylate, polypropylene glycol-mono (meth) acrylate, polybutylene glycol-mono (meth) acrylate, polyethylene glycol-polypropylene glycol-mono (meth) acrylate, polyethylene glycol-poly Butylene glycol-mono(meth)acrylate, polypropylene glycol-polybutylene glycol-mono(meth)acrylate, polyethylene glycol-polypropylene glycol-polybutylene glycol-mono(meth)acrylate; methoxypolyethylene glycol-(meth)acrylate, methoxypolypropylene glycol -(meth)acrylate, methoxypolybutylene glycol-(meth)acrylate, methoxy-polyethylene glycol-polypropylene glycol-(meth)acrylate, methoxy-polyethylene glycol-polybutylene glycol-(meth)acrylate, methoxy-polypropylene glycol-polybutylene Glycol-(meth)acrylate, methoxy-polyethyleneglycol-polypropyleneglycol-polybutyleneglycol-(meth)acrylate; ethoxypolyethyleneglycol-(meth)acrylate, ethoxypolypropyleneglycol-(meth)acrylate, ethoxypolybutyleneglycol-(meth)acrylate 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 and the like.
(A) When the total of (meth)acrylic acid ester monomers in which the number of carbon atoms in the alkyl group is C1 to C18 is 100 parts by weight, the (F) polyalkylene glycol mono(meth)acrylic acid ester monomer is added by 0 to 50 parts by weight. It is preferably contained in a ratio of 1 part. In the pressure-sensitive adhesive layer according to the present invention, the pressure-sensitive adhesive composition may not contain (F) polyalkylene glycol mono(meth)acrylate monomer.

The pressure-sensitive adhesive composition can optionally contain (H) a polyether-modified siloxane compound with an HLB value of 7-15. The polyether-modified siloxane compound is a siloxane compound having a polyether group, and in addition to the usual siloxane unit [-SiR ¹ ₂ -O-], a siloxane unit having a polyether group [-SiR ¹ (R ² O( R ³ O) _n R ⁴ )—O—]. Here, R ¹ is one or two or more alkyl groups or aryl groups, R ² and R ³ are one or two or more alkylene groups, and R ⁴ is one or two or more alkyl groups or acyl groups. etc. (end group). The polyether group includes polyoxyalkylene groups such as a polyoxyethylene group [(C ₂ H ₄ O) _n ] and a polyoxypropylene group [(C ₃ H ₆ O) _n ].

The polyether-modified siloxane compound is preferably a polyether-modified siloxane compound having an HLB value of 7-15. Further, with respect to 100 parts by weight of the acrylic polymer, the polyether-modified siloxane compound having an HLB value of 7 to 15 is 1.0 parts by weight or less (excluding 0 parts by weight), 0.01 to 1.0 parts by weight. It is preferably included in parts by weight. More preferably, it is 0.1 to 0.5 parts by weight.
HLB is the hydrophilic-lipophilic balance (hydrophilic-lipophilic ratio) defined, for example, in JIS K3211 (surfactant terms).

A polyether-modified siloxane compound can be obtained, for example, by grafting an organic compound having an unsaturated bond and a polyoxyalkylene group to a polyorganosiloxane main chain having a silicon hydride group through a hydrosilylation reaction. Specifically, dimethylsiloxane/methyl (polyoxyethylene) siloxane copolymer, dimethylsiloxane/methyl (polyoxyethylene) siloxane/methyl (polyoxypropylene) siloxane copolymer, dimethylsiloxane/methyl (polyoxypropylene) A siloxane polymer etc. are mentioned. The HLB value of the polyether-modified siloxane compound can be adjusted by selecting the ratio of polyether groups to siloxane groups.
By incorporating (H) a polyether-modified siloxane compound having an HLB value of 7 to 15 into the adhesive composition, the adhesive strength and stain resistance of the adhesive can be improved. If the pressure-sensitive adhesive composition does not contain a polyether-modified siloxane compound, the cost will be lower.

Furthermore, as other components, the pressure-sensitive adhesive composition according to the present invention contains known additives such as surfactants, curing accelerators, plasticizers, fillers, curing retarders, processing aids, anti-aging agents, and antioxidants. Additives can be appropriately blended. These are used alone or in combination of two or more.

The acrylic polymer used in the pressure-sensitive adhesive composition of the present invention is (A) a total of 100 parts by weight of (meth)acrylic acid ester monomers in which the alkyl group has C1 to C18 carbon atoms, and (a1) the alkyl group 1 to 30 parts by weight of at least one (meth)acrylic acid ester monomer having C1 to C4 carbon atoms, and (a2) at least one (meth)acrylic acid ester monomer having an alkyl group having C5 to C18 carbon atoms 70 to 99 parts by weight of and 0.1 to 12 parts by weight of (B) at least one copolymerizable monomer containing a hydroxyl group as a group of copolymerizable monomers. be able to. The copolymerizable monomer group may further include (F) a polyalkylene glycol mono(meth)acrylate monomer. The polymerization method of the acrylic polymer is not particularly limited, and an appropriate polymerization method such as solution polymerization or emulsion polymerization can be used.
The pressure-sensitive adhesive composition of the present invention comprises an acrylic polymer, (C) a difunctional or higher isocyanate compound, (D) a cross-linking accelerator, (E) a ketoenol tautomer compound, and optionally any additives. It can be prepared by

The acrylic polymer does not contain a copolymerizable monomer containing a carboxyl group and a nitrogen-containing vinyl monomer that does not contain a hydroxyl group as a group of copolymerizable monomers, thereby improving the crosslinking speed and stabilizing the adhesive force. is effective. It is preferable to use (B) a copolymerizable monomer containing a hydroxyl group as (C) a monomer that reacts with a di- or more functional isocyanate compound used as a cross-linking agent. Preferred monomer compositions of the acrylic polymer include one or more of each of (A) and (B), one or more of each of (A), (B), and (F). mentioned.

The pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition has an adhesive strength of 0.05 to 0.1 N/25 mm at a low peel speed of 0.3 m / min, and a high peel speed of 30 m / min. It is preferable that the adhesive strength is 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 peel off quickly even with high-speed peeling. Moreover, when the antistatic surface protection film is once peeled off for reattachment, it is easy to peel off from the adherend without requiring excessive force.

The pressure-sensitive adhesive layer formed by cross-linking 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 high, the performance of releasing static electricity generated by electrification is inferior when the antistatic surface protective film is peeled off from the adherend. Therefore, by sufficiently reducing the surface resistivity, the peeling electrification voltage caused by the static electricity generated when the adherend peels off the pressure-sensitive adhesive layer is reduced, and the electric control circuit of the adherend is not affected. can be suppressed.

The gel fraction of the pressure-sensitive adhesive layer (the pressure-sensitive adhesive after cross-linking) formed by crosslinking the pressure-sensitive adhesive composition of the present invention is preferably 95 to 100%. Due to such a high gel fraction, the adhesive strength does not become excessive at low peeling speeds, and the elution of unpolymerized monomers or oligomers from the acrylic polymer is reduced, resulting in stain resistance and high temperature/humidity. The durability of the adherend is improved, and contamination of the adherend can be suppressed.

The antistatic surface protective film of the present invention is obtained by forming a pressure-sensitive adhesive layer formed by cross-linking a pressure-sensitive adhesive composition on one side or both sides of a resin film. The antistatic surface protective film of the present invention is formed by forming a pressure-sensitive adhesive layer obtained by cross-linking the pressure-sensitive adhesive composition in which the above components (A) to (E) are blended in a well-balanced manner. It has excellent performance, excellent adhesion balance at low and high peel speeds, and also excellent durability performance and stain resistance. Therefore, it can be suitably used as a surface protective film for polarizing plates.

The thickness of the pressure-sensitive adhesive layer 2 used in the antistatic surface protection film 10 according to the present invention is not particularly limited, but is preferably about 5 to 40 μm, more preferably about 10 to 30 μm. The peel strength (adhesive force) of the antistatic surface protective film to the surface of the adherend is about 0.03 to 0.3 N / 25 mm, and the adhesive layer 2 having a weak adhesive force is from the adherend. It is preferable because it is excellent in operability when peeling off the antistatic surface protection film. Moreover, the peeling force of the release film 5 from the pressure-sensitive adhesive layer 2 is preferably 0.2 N/50 mm or less for excellent operability when the release film 5 is peeled off from the antistatic surface protection film 10 .

The release film 5 used in the antistatic surface protective film 10 according to the present invention is a resin composition containing a release agent containing dimethylpolysiloxane as a main component and an antistatic agent on one side of the resin film 3. The used release agent layer 4 is formed. Preferably, the release agent layer 4 further contains a silicone compound that is liquid at 20°C. The silicone-based compound in the release agent layer 4 is preferably polyether-modified silicone.

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, but a polyester film is particularly preferable because it has excellent transparency and is relatively inexpensive. . The resin film may be an unstretched film or a uniaxially or biaxially stretched film. Moreover, the draw ratio of the stretched film and the orientation angle in the axial direction formed along with the crystallization of the stretched film may be controlled to specific values.
The thickness of the resin film 3 is not particularly limited, but for example, a thickness of about 12 to 100 μm is preferable, and a thickness of about 20 to 50 μm is more preferable because it is easy to handle.
In addition, if necessary, the surface of the resin film 3 may be subjected to surface modification by corona discharge, easy-adhesion treatment such as application of an anchor coating agent.

Examples of release agents containing dimethylpolysiloxane as a main component that constitute 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 release agents. Products commercially available as addition reaction type silicone release agents include, for example, KS-776A, KS-847T, KS-779H, KS-837, KS-778, and KS-830 (manufactured by Shin-Etsu Chemical Co., Ltd.). , SRX-211, SRX-345, SRX-357, SD7333, SD7220, SD7223, LTC-300B, LTC-350G, LTC-310 (manufactured by Dow Corning Toray Co., Ltd.) and the like. Commercially available products of the condensation reaction type include, for example, SRX-290 and SYLOFF-23 (manufactured by Dow Corning Toray Co., Ltd.). Products commercially available as cationic polymerized products 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 the like. Examples of commercially available radical polymerizable products include X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.).

Examples of silicone compounds that are liquid at 20° C. and which constitute the release agent layer 4 include polyether-modified silicones, alkyl-modified silicones, carbinol higher fatty acid ester-modified silicones, and the like. In the present invention, in order to improve the antistatic properties of the surface of the pressure-sensitive adhesive layer, a silicone-based compound that is liquid at 20° C. in a compatible state in the release agent layer containing dimethylpolysiloxane as a main component is used. be done. Among modified silicone compounds, polyether-modified silicones are 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 the polyethylene oxide used in the side chain, physical properties such as compatibility with the silicone release agent and antistatic effect can be improved. is adjusted.
Products commercially available as polyether-modified silicones 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 BYK-Chemie) and the like.
The amount of the silicone compound that is liquid at 20°C to the release agent containing dimethylpolysiloxane as the main component varies depending on the type of silicone compound and the degree of compatibility with the release agent. It may be set in consideration of the desired peeling electrification voltage when peeling from the body, the staining property to the adherend, the adhesive properties, and the like.

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

Alkali metal salts include metal salts composed of lithium, sodium and potassium. Specifically, for example, cations consisting of Li ⁺ , Na ⁺ , K ⁺ , Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SCN ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , Metal salts composed of anions consisting of (FSO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ are preferred. used for Among them LiBr, LiI, _LiBF4 , _LiPF6 , LiSCN, _LiClO4 , _LiCF3SO3 , Li( _{FSO2 ) 2N , Li} ( _{CF3SO2 ) 2N} , Li( _C2F5SO2 ) ₂ N, lithium salts (Li salts) such as Li(CF ₃ SO ₂ ) ₃ C, especially Li(CF ₃ SO ₂ ) ₂ N abbreviated LiTFSI, Li(FSO ₂ ) ₂ N abbreviated LiFSI ”, LiCF ₃ SO ₃ “abbreviation LiTF or LiTf” 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 antistatic agent added to the release agent whose main component is dimethylpolysiloxane varies depending on the type of antistatic agent and the degree of affinity with the release agent. However, it may be set in consideration of the desired peeling electrification voltage, the staining property to the adherend, the adhesive property, and the like.

There is no particular limitation on the method of mixing the release agent containing dimethylpolysiloxane as a main component and the antistatic agent. A method in which an antistatic agent is added to a release agent whose main component is dimethylpolysiloxane, and after mixing, a catalyst for curing the release agent is added and mixed. A method in which an antistatic agent and a catalyst for curing the release agent are added and mixed after being diluted with a solvent, or a release agent whose main component is siloxane is first diluted in an organic solvent, the catalyst is added and mixed, and then the antistatic agent is added. may be added or mixed. Further, if necessary, an adhesion improver such as a silane coupling agent or a material for assisting the antistatic effect such as a compound containing a polyoxyalkylene group may be added.
The method of mixing the polyether-modified silicone with the release agent is the same as the method of mixing with the antistatic agent, and is not particularly limited.

The mixing ratio of the release agent containing dimethylpolysiloxane as the main component and the antistatic agent is not particularly limited. A ratio of about 5 to 100 minutes is preferable. When the added amount of the antistatic agent in terms of solid content is less than 5 with respect to 100 of the solid content of the release agent containing dimethylpolysiloxane as a main component, the amount of the antistatic agent transferred to the surface of the adhesive layer is also reduced. As a result, it becomes difficult for the pressure-sensitive adhesive to exhibit its antistatic function. In addition, when the amount of the antistatic agent added in terms of solid content exceeds 100 with respect to 100 solid content of the release agent containing dimethylpolysiloxane as the main component, the antistatic agent and dimethylpolysiloxane are used as the main component. The release agent is also transferred to the surface of the pressure-sensitive adhesive layer, which may reduce the adhesive properties of the pressure-sensitive adhesive.
The mixing ratio of the polyether-modified silicone to the release agent is preferably approximately the same as the mixing ratio of the antistatic agent, and is not particularly limited.

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

Forming the pressure-sensitive adhesive layer 2 on the surface of the substrate film 1 may be performed by a known method. Specifically, known coating methods such as reverse coating, comma coating, gravure coating, slot die coating, Meyer bar coating, and air knife coating can be used.

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

FIG. 2 is a cross-sectional view showing a state in which the release film has been peeled off from the antistatic surface protective film of the present invention.
By peeling off the release film 5 from the antistatic surface protective film 10 shown in FIG. It is transferred (adhered) to the surface of the adhesive layer 2 of 10 . Therefore, in FIG. 2, the antistatic agent transferred to the surface of the pressure-sensitive adhesive layer 2 of the antistatic surface protective film is schematically indicated by dots 7 .
In the antistatic surface protective film according to the present invention, when the antistatic surface protective film 11 with the release film shown in FIG. Also, the antistatic agent contacts the surface of the adherend. As a result, when the antistatic surface protection film is peeled off from the adherend again, the peeling electrification voltage can be kept low.

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 in a state where the adhesive layer 2 is exposed, the adhesive layer 2 is adhered to the optical component 8 as an adherend. be.
That is, FIG. 3 shows an optical component 20 laminated with the antistatic surface protective film 10 of the present invention. Examples of optical components include optical films such as a polarizing plate, a retardation plate, a lens film, a polarizing plate also used as a retardation plate, and a polarizing plate also used as a lens film. Such optical components are used as constituent members of various display devices such as liquid crystal display panels and organic EL display panels, optical system devices of various instruments, and the like. Optical parts also include optical films such as antireflection films, hard coat films, and transparent conductive films for touch panels. In particular, optical films such as low-reflection treated polarizing plates (LR polarizing plates) and anti-glare low-reflecting polarizing plates (AG-LR polarizing plates) whose surfaces are anti-fouling treated with silicone compounds, fluorine compounds, etc. It can be suitably used as an antistatic surface protection film to be laminated on a contaminated surface.
Examples of the low-reflection surface treatment layer of the LR polarizing plate include metal oxide thin films (such as deposited films of SiO ₂ and TiO ₂ ) and anti-reflection films such as fluororesin. Even when the antistatic surface protective film of the present invention is laminated with the adhesive layer of the antistatic surface protective film in contact with the antireflection film, the peeling electrostatic voltage is reduced and the adherend is less stained. can be compatible with
According to the optical component of the present invention, when the antistatic surface protection film 10 is peeled off from the adherend optical component (optical film), the peeling electrification voltage can be suppressed sufficiently low. There is no danger of destroying circuit components such as ICs, TFT elements, and gate line drive circuits, and it is possible to increase production efficiency in the process of manufacturing liquid crystal display panels, organic EL display panels, etc., and maintain the reliability of the production process. .

The present invention will now be further described by means of 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 to replace the air in the reactor with nitrogen gas. Then, 10 parts by weight of methyl acrylate, 90 parts by weight of 2-ethylhexyl acrylate, 5.0 parts by weight of 8-hydroxyoctyl acrylate, 10 parts by weight of polypropylene glycol monoacrylate (n=12) and 60 parts of solvent (ethyl acetate) were added to the reactor. Added parts by weight. Thereafter, 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 polymer solution of Example 1 having a weight average molecular weight of 500,000. rice field. After adding 8.5 parts by weight of acetylacetone to this acrylic polymer solution and stirring, 2.0 parts by weight of Coronate HX (an isocyanurate form of a hexamethylene diisocyanate compound) and 0.1 parts by weight of titanium trisacetylacetonate were added. was added and mixed with stirring to obtain a pressure-sensitive adhesive composition of Example 1.

[Examples 2 to 6 and Comparative Examples 1 to 3]
The 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 adhesive compositions of Example 1 were as described in Tables 1 and 2, respectively. got stuff In Tables 1 and 2, the monomers contained (copolymerized) in the acrylic polymer are (A), (B), (F), and "carboxyl group-containing monomer".

Tables 1 and 2 are an integral table showing the compounding ratio of each component divided into two, and in both cases the total weight of group (A) is 100 parts by weight. indicated by . In addition, Tables 3 and 4 show the compound names of the abbreviations of the components used in Tables 1 and 2. Coronate (registered trademark) HX, HL and L are trade names of Tosoh Corporation, and Takenate (registered trademark) D-140N, D-127N and D-110N are trade names of Mitsui Chemicals, Inc. . In "Antistatic agent" in Table 2 and in _Table 7 below, LiTFSI represents Li( _{CF3SO2 ) 2N} , LiFSI represents Li( _FSO2 ) _2N , and LiTF represents _LiCF3SO3 . In addition, in the compound used as the (F) polyalkylene glycol mono(meth)acrylic acid ester monomer in each example, the diester content in the monomer is 0.2% or less.

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

<Preparation of antistatic surface protective film>
[Example 1]
Addition 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, main components: dimethyl, methyl (polyethylene oxide Acetate)siloxane) 0.15 parts by weight, Li(CF ₃ SO ₂ ) ₂ N 0.5 parts by weight, 95 parts by weight of a 1:1 mixed solvent of toluene and ethyl acetate, and a platinum catalyst (Dow Corning Toray Co., Ltd.) Product name: SRX-212 Catalyst) was mixed with 0.05 parts by weight and stirred and mixed to prepare a paint for forming the release agent layer of Example 1. On the surface of a polyethylene terephthalate film with a thickness of 38 μm, the paint for forming the release agent layer of Example 1 was applied with a Meyer bar so that the thickness after drying would be 0.2 μm, and then placed in a hot air circulation 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 to the surface of a polyethylene terephthalate film having a thickness of 38 μm so that the thickness after drying was 20 μm, and then dried in a hot air circulating oven at 100° C. for 2 minutes. to form an adhesive layer. Thereafter, the release agent layer (silicone-treated surface) of the release film of Example 1 prepared above was laminated on the surface of this pressure-sensitive adhesive layer. The pressure-sensitive adhesive film thus obtained was kept at 40° C. for 5 days to cure the pressure-sensitive adhesive, and an antistatic surface protective film of Example 1 was obtained.

[Example 2]
Example 2 was carried out in the same manner as in Example 1 except that the adhesive composition of Example 1 was changed to the adhesive composition of Example 2, and the antistatic agent used in the release agent layer was LiCF ₃ SO ₃ . of the antistatic surface protection film was obtained.

[Examples 3 to 6]
Same as Example 1, except that the adhesive composition of Example 1 was replaced with the adhesive composition of Examples 3 to 6, and the antistatic agent used in the release agent layer was Li(FSO ₂ ) ₂ N. Then, antistatic surface protective films of Examples 3 to 6 were obtained.

[Comparative Example 1]
Addition reaction type silicone (manufactured by Dow Corning Toray 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 a platinum catalyst (manufactured by Dow Corning Toray Co., Ltd. , product name: SRX-212 Catalyst) was mixed with 0.05 parts by weight and stirred and mixed to prepare a paint for forming a release agent layer of Comparative Example 1. On the surface of a polyethylene terephthalate film with a thickness of 38 μm, the coating material for forming the release agent layer of Comparative Example 1 was applied with a Meyer bar so that the thickness after drying was 0.2 μm, and was placed in a hot air circulation 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 was 20 μm, and then dried in a hot air circulating 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 prepared above was laminated on the surface of this pressure-sensitive adhesive layer. The pressure-sensitive adhesive film obtained was kept at 40° C. for 5 days to cure the pressure-sensitive adhesive, and an antistatic surface protection film of Comparative Example 1 was obtained.

[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 adhesive composition of Comparative Example 1 was changed to the adhesive composition of Comparative Example 2.

[Comparative Example 3]
In the same manner as in Example 1, except that the adhesive composition of Example 1 was changed to the adhesive composition of Comparative Example 3, and the antistatic agent used in the release agent layer was Li(FSO ₂ ) ₂ N, An antistatic surface protective film of Comparative Example 3 was obtained.

Table 7 shows the compositions of the release agent layers in the antistatic surface protective films of Examples 1-6 and Comparative Examples 1-3.

<Test method and evaluation>
After aging the antistatic surface protective films in Examples 1 to 6 and Comparative Examples 1 to 3 in an atmosphere of 23 ° C. and 50% RH for 7 days, the release film (silicone resin-coated PET film) was peeled off. A surface resistivity measurement sample was prepared by exposing the pressure-sensitive adhesive layer.
Furthermore, the antistatic surface protection film with the pressure-sensitive adhesive layer exposed was adhered to the surface of the polarizing plate attached to the liquid crystal cell via the pressure-sensitive adhesive layer, and left to stand for one day. The sample was autoclaved for 20 minutes and allowed to stand at room temperature for 12 hours.

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

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

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

<Contamination>
A polarizing plate with a low-reflection surface treatment is placed on one side of a glass plate with an adhesive layer (for example, a double-sided adhesive tape that is different from the adhesive layer of the antistatic surface protection film) using a laminator. stick together. After that, an antistatic surface protective film is laminated on the surface of the polarizing plate using a laminating machine. After storing for 3 days and 30 days in an environment of 23° C. and 50% RH, the antistatic surface protective film is peeled off and the contamination state of the surface of the polarizing plate is visually observed.
The surface contamination of the surface of the polarizing plate is "○" when there is no contamination in both 3-day storage and 30-day storage, and when there is slight contamination in either 3-day storage or 30-day storage. was evaluated as "△", and the case with contamination was evaluated as "×".

Table 8 shows the evaluation results. In addition, the surface resistivity was expressed by a method of setting "m×10 ⁺ⁿ " to "mE+n" (where m is an arbitrary real number and n is a positive integer).

The measurement results shown in Table 8 reveal the following.
The antistatic surface protective films of Examples 1 to 6 according to the present invention have moderate adhesion, do not stain the surface of the adherend, and when the antistatic surface protective film is peeled off from the adherend Low stripping electrification voltage.
On the other hand, the antistatic surface protective film of Comparative Example 1, in which an antistatic agent was added to the adhesive layer, had a good low surface resistivity of the adhesive layer, but was slightly inferior in stain resistance.
Further, the antistatic surface protective film of Comparative Example 2, in addition to adding an antistatic agent to the adhesive layer, (a1) a (meth) acrylic acid ester monomer having an alkyl group having a carbon number of C1 to C4, and (B) The adhesive strength was high, the peeling electrification voltage was high, and the staining resistance was slightly inferior, probably because the added amount of the copolymerizable monomer containing a hydroxyl group was large.
In addition, in the antistatic surface protective film of Comparative Example 3, the acrylic polymer does not contain (a1) a (meth)acrylic acid ester monomer having an alkyl group having a carbon number of C1 to C4, and contains a monomer containing a carboxyl group. Therefore, the adhesive strength was large and the staining resistance was poor.
That is, in Comparative Examples 1 and 2 in which an antistatic agent is mixed in the pressure-sensitive adhesive layer, it is difficult to achieve both reduction in peeling electrification voltage and low contamination of adherends. On the other hand, in Examples 1 to 6 in which an antistatic agent was added to the release agent layer and then the antistatic agent contained in the release agent layer was transferred to the surface of the adhesive layer, a small amount of antistatic agent was added to the release agent layer. Since the addition of the agent has the effect of reducing the peeling electrification voltage, the adherend was not contaminated, and a good antistatic surface protective film was obtained.

The antistatic surface protective film of the present invention can be used, for example, in the production process of optical films such as polarizing plates, retardation plates, and lens films for displays, and other various optical parts. can be used to protect In particular, when used as an antistatic surface protective film for optical films such as LR polarizing plates and AG-LR polarizing plates whose surfaces have been antifouling-treated with silicone compounds, fluorine compounds, etc., peeling from the adherend When doing so, the amount of static electricity generated can be reduced.
The antistatic surface protective film of the present invention causes less contamination on adherends and has excellent peeling antistatic performance without deterioration over time, so it improves the yield of production processes such as optical films and optical parts. It has great industrial utility value.

DESCRIPTION OF SYMBOLS 1... Base film, 2... Adhesive layer, 3... Resin film, 4... Release agent layer, 5... Release film, 7... Antistatic agent, 8... Adherend (optical component), 10... Antistatic surface protection Film 11...Antistatic surface protective film from which the peeling film was removed, 20...An optical part laminated with the antistatic surface protective film.

Claims (3)

A pressure-sensitive adhesive layer obtained by cross-linking a pressure-sensitive adhesive composition containing an acrylic polymer and a cross-linking agent is formed on one side of a substrate made of a resin having transparency, and a resin is formed on the surface of the pressure-sensitive adhesive layer. An antistatic surface protective film in which a release film having a release agent layer containing an antistatic agent laminated on one side of the film is laminated via the release agent layer,
The release agent layer is formed using a resin composition containing a release agent containing dimethylpolysiloxane as a main component, a silicone compound that is liquid at 20° C., and an antistatic agent,
The acrylic polymer is
(A) a total of 100 parts by weight of a (meth)acrylic acid ester monomer having an alkyl group with a carbon number of C1 to C18;
(B) 0.1 to 12 parts by weight of at least one copolymerizable monomer containing a hydroxyl group;
(F) 5 to 20 parts by weight of a polyalkylene glycol mono(meth)acrylate monomer,
Consists of an acrylic polymer of a copolymer obtained by copolymerizing
Of the total 100 parts by weight of the (A) alkyl group having a carbon number of C1 to C18 (meth)acrylic acid ester monomer,
(a1) 1 to 30 parts by weight of at least one (meth)acrylic acid ester monomer having an alkyl group with a carbon number of C1 to C4;
(a2) containing at least one (meth)acrylic acid ester monomer having an alkyl group with a carbon number of C5 to C18 in a proportion of 70 to 99 parts by weight;
The acrylic polymer does not copolymerize a copolymerizable monomer containing a carboxyl group and a nitrogen-containing vinyl monomer containing no hydroxyl group,
At least one selected from the group of compounds consisting of methyl (meth)acrylate and ethyl (meth)acrylate among at least one (a1) (meth)acrylic acid ester monomer in which the alkyl group has C1 to C4 carbon atoms comprising seeds,
The pressure-sensitive adhesive composition further contains (C) a bifunctional or higher isocyanate compound, (D) a cross-linking accelerator, and (E) a ketoenol tautomer compound, and contains an antistatic agent. not
An antistatic surface protection film, wherein the pressure-sensitive adhesive layer has a surface resistivity of 5.0×10 ⁺¹² Ω/□ or less and a peeling electrostatic voltage of ±0.6 kV or less. An optical film in which the antistatic surface protection film according to claim 1 is laminated with the release film removed . An optical component comprising the antistatic surface protection film according to claim 1 and the release film being peeled off .

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