Method for manufacturing antistatic surface protective film and antistatic surface protective film

Abstract

To provide a method for manufacturing an antistatic surface protective film, and the antistatic surface protective film, which is excellent in ambient air exposure property of an antistatic layer formed on a surface of a base material, is effective for storage over a long period of time, has a balanced adhesive ability at both low peeling speed and high peeling speed when the adhesive layer is peeled, and is excellent in antistatic performance of the adhesive layer and anti-contamination performance.SOLUTION: An antistatic surface protective film 10 in which an adhesive layer 2, obtained by crosslinking an adhesive composition containing an acrylic polymer and a crosslinking agent, is formed on one surface of a base material film 1 made of a transparent resin, where an antistatic layer 6 containing only a carbon nanotube and a hydroxyl group-containing polymer as a first antistatic agent (K1) is formed on the other surface of the base material film 1, and a peeling film 5, in which a peeling agent layer 4 containing a second antistatic agent (K2) is laminated on one surface of a resin film 3, is bonded to the surface of the adhesive layer 2 through the peeling agent layer 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a surface protection film used in the manufacturing process of optical components constituting liquid crystal displays (LCDs), organic EL display devices, etc. More specifically, the present invention relates to a method for manufacturing an antistatic surface protection film used to protect the surfaces of optical components such as polarizing plates and retardation plates by adhering the film to the surfaces of optical components constituting liquid crystal displays, etc., and the antistatic surface protection film. [Background technology]

[0002] Conventionally, surface protection films having a pressure-sensitive adhesive layer provided on one side of a substrate film have been commonly used to prevent scratches and dirt from adhering during the manufacturing process of optical products. The surface protection film is attached to an optical component such as an optical film via a pressure-sensitive adhesive layer with weak adhesive strength. The pressure-sensitive adhesive layer has weak adhesive strength so that when a used surface protection film is peeled off and removed from the surface of the optical film, it can be easily peeled off and the pressure-sensitive adhesive does not adhere to and remain on the optical film of the adherend product (preventing the occurrence of so-called adhesive residue).

[0003] Furthermore, as a conventional technique, a technique has been disclosed in which an antistatic layer is laminated on the surface of the substrate (polyester film) of a surface protection film for optical components, and a conductive polymer is used as the antistatic agent contained in the antistatic layer (for example, Patent Documents 1 to 3). Some of the techniques using the conductive polymer are still in use today. However, when a surface protection film containing a conductive polymer in the antistatic layer is stored in the atmosphere for a long period of time, the surface resistivity of the antistatic layer increases over time, resulting in a decrease in antistatic performance (so-called poor atmospheric exposure resistance).

[0004] Furthermore, in recent years, in addition to the conventionally used triacetyl cellulose (TAC) as a protective layer (sometimes called a protective film) for the polarizer of a polarizing plate, a type of optical component, the use of materials that are prone to peeling static electricity when the surface protective film of the polarizing plate is peeled off, such as acrylic resins such as polymethyl methacrylate (PMMA), polyester resins such as polyethylene terephthalate (PET), cyclic olefin polymers, and polycarbonates, has been investigated and is being widely adopted (e.g., Patent Document 4). For this reason, the pressure-sensitive adhesive layer for the surface protective film of the polarizing plate must have better antistatic properties than conventional materials. Here, TAC is an abbreviation for triacetyl cellulose, PMMA is an abbreviation for polymethyl methacrylate, and PET is an abbreviation for polyethylene terephthalate. In applications where the surface protective film for polarizing plates is used, various surface treatments are applied to the surface of the protective layer of the polarizer of the polarizing plate to be adhered, such as untreated, AG treatment, LR treatment, AR treatment, AG-LR treatment, and AG-AR treatment, where AG stands for anti-glare, LR stands for low reflection, and AR stands for anti-reflection.

[0005] As described above, surface protection films for polarizing plates in recent years have been required to cope with the situation in which a wide variety of materials are used for the protective layer of the polarizer of the polarizing plate to be adhered. Furthermore, in terms of the usage patterns of surface protection films for optical components, there has been an increase in the opportunities for use in various manufacturing processes of optical components, and there has also been an increase in the proportion of those used in processes in which optical components are stored for long periods of time with the surface protection film attached to them. Furthermore, even after the manufacturing process of optical components is completed, there has been an increase in the opportunities for the manufactured optical components to be stored for long periods of time with the surface protection film attached to them until they are incorporated into devices such as liquid crystal displays (LCDs). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-169455 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-338379 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-223923 [Patent Document 4] Japanese Patent Application Publication No. 2017-165086 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, in the prior art, when a surface protection film containing a conductive polymer in an antistatic layer is stored in the atmosphere for a long period of time, the antistatic performance of the antistatic layer deteriorates due to changes over time, which has become apparent. However, no technology capable of solving this problem has been found to date. Furthermore, in recent years, surface protection films have been required to have adhesive strengths at high and low peeling speeds in the process of being attached to adherends made of various materials and then peeled from the respective adherends, both of which are within a predetermined adhesive strength range, and to have excellent antistatic properties in the adhesive layer and excellent stain resistance on the adherend.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing an antistatic surface protective film, and an antistatic surface protective film, in which the antistatic layer formed on the surface of a substrate has excellent atmospheric exposure properties and is therefore effective for long-term storage, and which has balanced adhesive strength at both low and high peeling speeds when the pressure-sensitive adhesive layer is peeled off, and in which the pressure-sensitive adhesive layer has excellent antistatic performance and contamination resistance. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve these problems. First, when a surface protection film containing a conductive polymer in the antistatic layer is stored in the atmosphere for a long period of time, the surface resistivity of the antistatic layer increases over time, causing a decrease in antistatic performance (so-called poor atmospheric exposure resistance). Although the reason for this phenomenon is not clear, it was hypothesized that the conductive polymer is oxidized and deteriorated by moisture and oxygen in the atmosphere. Therefore, we searched for a material that would not be oxidized and deteriorated by moisture and oxygen in the atmosphere, and that had high total light transmittance and electrical conductivity. As a result, we were finally able to solve this problem by adopting carbon nanotubes as the antistatic agent (K1) in the antistatic layer.

[0010] Furthermore, another problem of obtaining an antistatic surface protective film that has balanced adhesive strength at both low and high peeling speeds when the adhesive layer is peeled off, and that has excellent antistatic performance and contamination resistance of the adhesive layer, can be solved as follows. In order to solve this problem, the adhesive composition for forming the adhesive layer of the antistatic surface protection film of the present invention is an acrylic polymer contained in the adhesive composition, which is an acrylic polymer consisting of a copolymer having a weight average molecular weight of more than 300,000 and not more than 1,000,000, obtained by copolymerizing a total of 100 parts by weight of (A) at least one alkyl (meth)acrylate having an alkyl group carbon number of C1 to C18 and a total of 1.0 to 6.0 parts by weight of (B) at least one copolymerizable monomer containing a hydroxyl group, without containing a copolymerizable monomer having a carboxyl group. Furthermore, after the adhesive composition is coated and dried to form an adhesive layer, an appropriate amount of a liquid silicone compound and an antistatic agent (K2) at 20°C are applied to the surface of the adhesive layer. This not only reduces the contamination of the adherend (has contamination resistance), but also reduces the peeling electrification voltage when peeling from the adherend, i.e., the optical film, thereby solving this problem.

[0011] 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 (4): Step (1): A pressure-sensitive adhesive composition containing an acrylic polymer and a crosslinking agent, wherein the acrylic polymer is an acrylic polymer consisting of a copolymer having a weight-average molecular weight of more than 300,000 and not more than 1,000,000, obtained by copolymerizing 100 parts by weight of at least one alkyl (meth)acrylate (A) having a carbon number of C1 to C18 in the alkyl group and 1.0 to 6.0 parts by weight of at least one copolymerizable monomer (B) having a hydroxyl group, without containing a copolymerizable monomer having a carboxyl group; a step of preparing a pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition comprising (C) a trifunctional or higher isocyanate compound as the crosslinking agent, (D) a crosslinking retarder, and (E) a crosslinking accelerator other than a tin compound as a crosslinking accelerator; Step (2): forming a pressure-sensitive adhesive layer by crosslinking the pressure-sensitive adhesive composition on one surface of a substrate film made of a transparent resin; Step (3): forming an antistatic layer containing carbon nanotubes as a first antistatic agent (K1) on the other surface of the base film, the other surface being the surface opposite to the one surface; Step (4): A step of bonding a release film, which has a resin film and a release agent layer containing a second antistatic agent (K2) laminated on one side thereof, to the surface of the pressure-sensitive adhesive layer via the release agent layer, and transferring the second antistatic agent (K2) in the release agent layer to the surface of the pressure-sensitive adhesive layer; is produced through steps (1) to (4) in this order, The present invention provides a method for producing an antistatic surface protective film, characterized in that the release agent layer is formed from a resin composition containing a release agent mainly composed of dimethylpolysiloxane, a silicone-based compound that is liquid at 20°C, and the second antistatic agent (K2).

[0012] Furthermore, an antistatic surface protective film obtained by laminating a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition to a thickness of 15 μm on one side of a polyester film having a thickness of 38 μm, and transferring the second antistatic agent (K2) to the surface of the pressure-sensitive adhesive layer is bonded to the surface of a polarizing plate, and then the antistatic surface protective film is peeled from the polarizing plate, and the adhesive strength at a low peeling speed of 0.3 m / min is preferably 0.01 to 0.1 N / 25 mm, and at a high peeling speed of 30 m / min is preferably 1.0 N / 25 mm or less.

[0013] The initial surface resistivity of the antistatic layer on the surface of the base film is 1.0×10 +10 Ω / □ or less, and the surface resistivity of the antistatic layer after storage in an atmosphere of 23°C x 50% RH for 90 days in a state of being exposed to the air is 1.0 x 10 +10 It is preferably Ω / □ or less.

[0014] At least one of the pressure-sensitive adhesive composition and the acrylic polymer preferably contains (F) a polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer that constitutes a polyalkylene glycol chain.

[0015] The second antistatic agent (K2) is preferably an alkali metal salt.

[0016] The present invention also provides an antistatic surface protection film comprising a substrate film made of a transparent resin and a pressure-sensitive adhesive layer formed on one surface thereof, the pressure-sensitive adhesive layer being formed by crosslinking a pressure-sensitive adhesive composition containing an acrylic polymer and a crosslinking agent, The acrylic polymer (A) 100 parts by weight of at least one alkyl (meth)acrylate having an alkyl group carbon number of C1 to C18; (B) 1.0 to 6.0 parts by weight of at least one copolymerizable monomer containing a hydroxyl group; an acrylic polymer consisting of a copolymer having a weight average molecular weight of more than 300,000 and not more than 1,000,000, which is copolymerized without containing a copolymerizable monomer having a carboxyl group, the pressure-sensitive adhesive composition comprises (C) a tri- or higher functional isocyanate compound as the crosslinking agent, (D) a crosslinking retarder, and (E) a crosslinking accelerator other than a tin compound; an antistatic layer containing carbon nanotubes as a first antistatic agent (K1) formed on the other surface of the base film, the other surface being opposite to the one surface; a release film, which has a resin film and a release agent layer containing a second antistatic agent (K2) laminated on one surface of the resin film, is bonded to the surface of the pressure-sensitive adhesive layer via the release agent layer, and the second antistatic agent (K2) in the release agent layer is transferred to the surface of the pressure-sensitive adhesive layer; The release agent layer is formed from a resin composition containing a release agent mainly composed of dimethylpolysiloxane, a silicone-based compound that is liquid at 20°C, and the second antistatic agent (K2).

[0017] At least one of the pressure-sensitive adhesive composition and the acrylic polymer preferably contains (F) a polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer that constitutes the polyalkylene glycol chain.

[0018] The second antistatic agent (K2) is preferably an alkali metal salt.

[0019] The antistatic surface protection film is used as a surface protection film for a polarizing plate, and the protective layer of the polarizer of the polarizing plate is preferably one selected from the group consisting of a TAC-based film, a PMMA-based film, and a PET-based film, and the surface treatment applied to the surface of the protective layer of the polarizer of the polarizing plate is preferably one selected from the group consisting of untreated, AG treatment, LR treatment, AR treatment, AG-LR treatment, and AG-AR treatment.

[0020] The (B) hydroxyl group-containing copolymerizable monomer is preferably at least one selected from the group consisting of 8-hydroxyoctyl(meth)acrylate, 6-hydroxyhexyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and N-hydroxyethyl(meth)acrylamide.

[0021] It is preferable that the (D) crosslinking retarder is a keto-enol tautomer compound, and the (D) crosslinking retarder is contained in a proportion of 0.1 to 300 parts by weight relative to 100 parts by weight of the acrylic polymer; the (E) crosslinking accelerator is at least one metal chelate compound selected from the group consisting of aluminum chelate compounds, titanium chelate compounds, and iron chelate compounds, and the (E) crosslinking accelerator is contained in a proportion of 0.001 to 0.5 parts by weight relative to 100 parts by weight of the acrylic polymer; and the weight ratio (D) / (E) of the (D) / (E) is 80 to 1000.

[0022] The pressure-sensitive adhesive composition preferably contains 0.01 to 0.5 parts by weight of a polyether-modified siloxane compound having an HLB value of 6 to 12 and a weight-average molecular weight of 10,000 or less, relative to 100 parts by weight of the acrylic polymer.

[0023] It is preferable that the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer has an average repeat number of 3 to 14 alkylene oxides constituting the polyalkylene glycol chain, the diester content in the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer is 0.2% or less, and the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer contains at least one selected from the group consisting of polyalkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, and ethoxypolyalkylene glycol (meth)acrylate in an amount of 1 to 50 parts by weight per 100 parts by weight of the acrylic polymer.

[0024] The silicone compound is preferably a polyether-modified silicone.

[0025] The second antistatic agent (K2) is a Li salt, and is preferably at least one selected from the group consisting of LiTFSI, LiFSI, and LiTF. [Effects of the Invention]

[0026] The antistatic surface protective film according to the present invention can exhibit the following effects (1) to (3). (1) The antistatic surface protective film of the present invention has an antistatic layer formed on the surface of a substrate that is excellent in resistance to exposure to the atmosphere, and therefore can provide an antistatic surface protective film that is effective for long-term storage. (2) The antistatic surface protective film of the present invention can provide an antistatic surface protective film having a well-balanced adhesive strength at both low and high peeling speeds when peeling the adhesive layer. (3) The antistatic surface protective film of the present invention causes little contamination of an adherend, and its contamination resistance to an adherend does not change over time. Furthermore, according to the present invention, even if the surface of an adherend, such as an LR polarizing plate or an AG-LR polarizing plate, on the side to which the antistatic surface protective film is attached is an optical film that has been treated with an anti-contamination agent such as a silicone compound or a fluorine compound, the release film is peeled off, and the antistatic surface protective film is attached to the adherend, and then the peeling electrification voltage that occurs when the antistatic surface protective film is peeled off and then peeled from the adherend can be kept low, thereby providing an antistatic surface protective film that does not deteriorate over time and has excellent peel-off antistatic performance. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a cross-sectional view illustrating the concept of an antistatic surface protective film of the present invention. [Figure 2] 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. [Figure 3] FIG. 1 is a cross-sectional view showing one embodiment of an optical component of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will be described in detail below based on embodiments. 1 is a cross-sectional view showing the concept of an antistatic surface protection film of this embodiment. This antistatic surface protection film 10 has a pressure-sensitive adhesive layer 2 formed on one surface of a transparent substrate film 1. A release film 5, which has a release agent layer 4 formed on the surface of a resin film 3, is attached to the surface of this pressure-sensitive adhesive layer 2. Furthermore, on the other surface of the transparent substrate film 1, which is the surface opposite to the one surface, an antistatic layer 6 containing carbon nanotubes as a first antistatic agent (K1) is formed. Furthermore, the release film 5 is laminated with a release agent layer 4 containing a second antistatic agent (K2).

[0029] A substrate film made of a transparent and flexible resin is preferably used as the substrate film 1 used in the antistatic surface protective film 10 according to this embodiment. This allows visual inspection of the optical component, which is the adherend, with the antistatic surface protective film attached to the optical component. The film made of a transparent resin used as the base film 1 is preferably a polyester film such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, or polybutylene terephthalate. In addition to polyester films, films made of other resins can also be used as long as they have the required strength and optical suitability. The base film 1 may be an unstretched film or a uniaxially or biaxially stretched film. The stretching ratio of the stretched film and the axial orientation angle formed by crystallization of the stretched film may be controlled to specific values.

[0030] The thickness of the substrate film 1 used in the antistatic surface protection film 10 according to this embodiment is not particularly limited, but a thickness of, for example, about 12 to 100 μm is preferred, and a thickness of about 20 to 50 μm is more preferred as it is easier to handle. If necessary, an antifouling layer for preventing surface contamination, a hard coat layer for scratch prevention, or the like may be provided on the other surface of the substrate film 1 in addition to the antistatic layer 6. Furthermore, one or the other surface of the substrate film 1 may be subjected to an adhesion-enhancing treatment such as surface modification by corona discharge or application of an anchor coating agent.

[0031] Furthermore, the antistatic layer 6 formed on the antistatic surface protection film 10 according to this embodiment contains carbon nanotubes as the first antistatic agent (K1). Carbon nanofibers are known as conductive materials, but ordinary carbon nanofibers have a problem of reduced transmittance due to their high light absorption in the visible light region. On the other hand, the carbon nanotubes used in the antistatic layer 6 of this embodiment have a hollow molecular structure, and therefore can suitably impart conductivity to the antistatic layer 6 while maintaining a high total light transmittance of the antistatic layer 6. That is, since the carbon nanotubes serving as the first antistatic agent (K1) have excellent electrical conductivity, the content of the carbon nanotubes in the antistatic layer 6 can be set to a relatively low concentration. This makes it possible to obtain an antistatic layer 6 having high total light transmittance and excellent antistatic performance, and the antistatic performance is stable when the antistatic layer 6 is heated or humidified, and therefore this is preferred.

[0032] The carbon nanotubes used as the first antistatic agent (K1) may be carbon nanotubes manufactured by known manufacturing methods such as catalyst-supported vapor phase growth, vapor phase flow method, and arc discharge method. Specific examples include single-walled carbon nanotubes and multi-walled carbon nanotubes with an average diameter of 0.3 to 100 nm. Multi-walled carbon nanotubes are considered to be cheaper than single-walled carbon nanotubes because they are relatively easy to mass-produce.

[0033] Commercially available single-walled carbon nanotubes include, for example, the SWeNT series manufactured by Toray Industries, Inc., the MWNT series manufactured by Nikkiso Co., Ltd., and TUBALL (registered trademark) manufactured by OCSiAl Inc. Commercially available multi-walled carbon nanotubes include, for example, the VGCF (registered trademark) series manufactured by Showa Denko K.K., and Baytubes (registered trademark) manufactured by Bayer AG.

[0034] The antistatic layer 6 contains carbon nanotubes as the first antistatic agent (K1), but it is preferable that in addition to the first antistatic agent (K1), it also contains at least one polymer, such as a hydroxyl group-containing polymer, as a binder. By adding at least one type of polymer such as a hydroxyl group-containing polymer as a binder to the antistatic layer 6, the dispersibility of the carbon nanotubes is improved. Examples of the binder include epoxy resin, phenol resin, acrylic resin, polyethylene glycol, polyvinyl alcohol, polyvinyl butyral, polyvinyl alcohol-polyethylene copolymer, polyvinyl acetal, polyvinyl alcohol-polyvinyl acetal copolymer, polyvinyl alcohol-polyvinyl butyral copolymer, and the like. In order to suppress deterioration of the antistatic layer 6, it is preferable that the antistatic layer 6 does not contain a conductive polymer. The binder may be an electrically insulating polymer. If the binder is a polymer that does not have a π-conjugated system, it is preferable because it is less susceptible to oxidative deterioration.

[0035] The content of carbon nanotubes in the antistatic layer 6 is preferably 0.1 to 30% by weight, more preferably 0.3 to 12% by weight, and particularly preferably 0.6 to 8.0% by weight, relative to 100% by weight of the total solid content of the antistatic layer 6. If the carbon nanotube content is less than 0.1% by weight, sufficient antistatic performance may not be obtained, and if the carbon nanotube content exceeds 30% by weight, the production cost increases unnecessarily, which is undesirable.

[0036] The thickness of the antistatic layer 6 formed on the antistatic surface protection film 10 according to this embodiment is preferably 0.01 to 0.8 μm, and more preferably 0.03 to 0.5 μm. The thin thickness of the antistatic layer 6 makes it easy to increase the total light transmittance of the antistatic layer 6 .

[0037] The pressure-sensitive adhesive layer 2 used in the antistatic surface protection film 10 according to this embodiment is not particularly limited as long as it adheres to the surface of the adherend, can be easily peeled off after use, and is unlikely to contaminate the adherend. In consideration of durability after attachment to an optical film, it is common to use an acrylic pressure-sensitive adhesive layer obtained by crosslinking an acrylic polymer as the pressure-sensitive adhesive layer 2.

[0038] Examples of the adhesive composition constituting the adhesive layer 2 include an acrylic polymer consisting of a copolymer having a weight average molecular weight of more than 300,000 and not more than 1,000,000, obtained by copolymerizing (A) 100 parts by weight of at least one alkyl (meth)acrylate having an alkyl group with a carbon number of C1 to C18 and (B) 1.0 to 6.0 parts by weight of at least one copolymerizable monomer having a hydroxyl group, without containing a copolymerizable monomer having a carboxyl group; (C) a tri- or higher functional isocyanate compound as a crosslinking agent; (D) a crosslinking retarder; and (E) a crosslinking accelerator other than a tin compound as a crosslinking accelerator.

[0039] Examples of the alkyl (meth)acrylate (A) having an alkyl group with a carbon number of C1 to C18 include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, and isononyl (meth)acrylate. acrylate, decyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, myristyl (meth)acrylate, isomyristyl (meth)acrylate, cetyl (meth)acrylate, isocetyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, etc. The alkyl group of these alkyl (meth)acrylates may be acyclic (straight-chain or branched) or cyclic (monocyclic or polycyclic).

[0040] The acrylic polymer preferably contains, out of a total of 100 parts by weight of (A), 50 parts by weight or more of 2-ethylhexyl acrylate and 5 to 40 parts by weight of a total of one or more monofunctional alkyl (meth)acrylate monomers having a homopolymer Tg of 0° C. or higher. In this specification, (meth)acrylate is a general term for acrylate and methacrylate. In addition, 2-ethylhexyl acrylate is preferably contained in an amount of 50 parts by weight or more, more preferably 60 parts by weight or more, and particularly preferably 70 parts by weight or more, of a total of 100 parts by weight of (A). Furthermore, the total amount of one or more monofunctional alkyl (meth)acrylate monomers having a Tg of 0°C or higher is preferably 5 to 40 parts by weight, more preferably 8 to 40 parts by weight, and particularly preferably 10 to 35 parts by weight, out of 100 parts by weight of the total of (A). In the following description, when the Tg of a monomer is simply referred to, it may refer to the Tg of the homopolymer.

[0041] The (B) copolymerizable monomer containing a hydroxyl group used in the acrylic polymer is preferably at least one selected from the group consisting of 8-hydroxyoctyl(meth)acrylate, 6-hydroxyhexyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, and the like. The acrylic polymer preferably contains 1.0 to 6.0 parts by weight, more preferably 2.0 to 6.0 parts by weight, and particularly preferably 2.5 to 5.5 parts by weight of at least one copolymerizable monomer containing a hydroxyl group (B) relative to 100 parts by weight of the total of (A).

[0042] The acrylic polymer is preferably further copolymerized with (F) a polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer that constitutes the polyalkylene glycol chain. Furthermore, (F) the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer that constitutes the polyalkylene glycol chain may be added to the pressure-sensitive adhesive composition as a component separate from the acrylic polymer. In either case, the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer can function as an antistatic adjuvant.

[0043] The polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer may be a compound in which one of the hydroxyl groups of a polyalkylene glycol is esterified as a (meth)acrylic acid ester. The (meth)acrylic acid ester group serves as a polymerizable group, and can be copolymerized with the acrylic polymer. It may be a polyalkylene glycol mono(meth)acrylate in which the other hydroxyl groups remain as OH, or an alkoxy polyalkylene glycol mono(meth)acrylate in which the other hydroxyl groups are converted to alkyl ethers. It should be noted that polyalkylene glycol mono(meth)acrylates fall under the category of (F) above, and therefore are not classified as (B) above even though they contain hydroxyl groups.

[0044] The polyalkylene glycol constituting the polyalkylene glycol chain may be any glycol compound having one or more alkylene groups, and examples thereof include polyethylene glycol, polypropylene glycol, polybutylene glycol, polyethylene glycol-polypropylene glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, and polyethylene glycol-polypropylene glycol-polybutylene glycol.

[0045] The polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer preferably has an average repeat number of 3 to 14 alkylene oxides constituting the polyalkylene glycol chain. Here, the "average repeat number of alkylene oxide" refers to the average number of repeating alkylene oxide units in the "polyalkylene glycol chain" portion contained in the molecular structure of the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer.

[0046] The polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer preferably contains a diester content of 0.2% or less. The "diester content in the monomer" refers to the content (wt%) of polyalkylene glycol di(meth)acrylic acid ester contained in the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer.

[0047] The polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer is preferably at least one selected from the group consisting of polyalkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, and ethoxypolyalkylene glycol (meth)acrylate.

[0048] The acrylic polymer preferably contains (copolymerizes) at least one polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer selected from the group consisting of polyalkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, and ethoxypolyalkylene glycol (meth)acrylate in an amount of 1 to 50 parts by weight, more preferably 1 to 35 parts by weight, and particularly preferably 1 to 25 parts by weight, per 100 parts by weight of the acrylic polymer.

[0049] The method for producing the acrylic polymer is not particularly limited, and any known polymerization method such as solution polymerization, emulsion polymerization, etc. The acrylic polymer preferably has a weight average molecular weight of more than 300,000 and not more than 1,000,000.

[0050] The acrylic polymer is copolymerized without containing a copolymerizable monomer having a carboxyl group. The acid value of the acrylic polymer is preferably 0.1 to 1.0 or less, and more preferably 0.0. This improves stain resistance. Here, the "acid value" is an index representing the acid content and is expressed as the number of milligrams of potassium hydroxide required to neutralize 1 g of a polymer containing a carboxyl group.

[0051] The pressure-sensitive adhesive composition according to this embodiment further contains (C) a trifunctional or higher isocyanate compound as a crosslinking agent. Examples of the trifunctional or higher isocyanate compound (C) include biuret-modified or isocyanurate-modified diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, and xylylene diisocyanate, as well as adducts with trivalent or higher polyols such as trimethylolpropane and glycerin. The proportion of the tri- or higher functional isocyanate compound (C) is preferably 0.1 to 10 parts by weight, and more preferably 0.1 to 6 parts by weight, per 100 parts by weight of the acrylic polymer.

[0052] The pressure-sensitive adhesive composition according to this embodiment contains (D) a crosslinking retarder. Examples of (D) crosslinking retarders include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate, and β-diketones such as acetylacetone, 2,4-hexanedione, and benzoylacetone. These are keto-enol tautomer compounds that block the isocyanate groups of (C) a trifunctional or higher isocyanate compound, thereby suppressing excessive viscosity increase and gelation of the pressure-sensitive adhesive composition after the addition of a crosslinking agent, and thereby extending the pot life of the pressure-sensitive adhesive composition. (D) The crosslinking retarder is preferably at least one selected from the group consisting of acetylacetone and ethyl acetoacetate. The pressure-sensitive adhesive composition preferably contains 0.1 to 300 parts by weight of the crosslinking retarder (D) relative to 100 parts by weight of the acrylic polymer.

[0053] The pressure-sensitive adhesive composition according to this embodiment contains a crosslinking accelerator (E) other than a tin compound. When the trifunctional or higher isocyanate compound (C) is used as the crosslinking agent, the crosslinking accelerator (E) may be any substance that functions as a catalyst for the reaction (crosslinking reaction) between the acrylic polymer and the crosslinking agent. A metal chelate compound is preferred as the crosslinking accelerator (E). A metal chelate compound is a compound in which one or more polydentate ligands L are bound 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.

[0054] Specific examples of metal chelate compounds include iron tris(2,4-pentanedionato)(III), iron trisacetylacetonate, titanium trisacetylacetonate, ruthenium trisacetylacetonate, zinc bisacetylacetonate, aluminum trisacetylacetonate, zirconium tetrakisacetylacetonate, iron tris(2,4-hexanedionato)(III), zinc bis(2,4-hexanedionato), titanium tris(2,4-hexanedionato), aluminum tris(2,4-hexanedionato), and zirconium tetrakis(2,4-hexanedionato).

[0055] The (E) crosslinking accelerator is preferably at least one metal chelate compound selected from the group consisting of aluminum chelate compounds, titanium chelate compounds, and iron chelate compounds. The pressure-sensitive adhesive composition preferably contains 0.001 to 0.5 parts by weight of (E) a crosslinking accelerator relative to 100 parts by weight of the acrylic polymer.

[0056] The crosslinking retarder (D) has the effect of suppressing crosslinking, in contrast to the crosslinking accelerator (E). Therefore, it is preferable to appropriately set the ratio of the crosslinking retarder (D) to the crosslinking accelerator (E). In order to extend the pot life of the pressure-sensitive adhesive composition and improve its storage stability, the weight part ratio (D) / (E) of (D) to (E) is preferably 80 to 1000, more preferably 80 to 700, and particularly preferably 80 to 300. Here, the ratio of parts by weight of (D) / (E) is the quotient obtained by dividing the parts by weight of (D) by the parts by weight of (E).

[0057] The pressure-sensitive adhesive composition according to the present embodiment may contain, as an optional component, (G) a polyether-modified siloxane compound. The polyether-modified siloxane compound is a siloxane compound having a polyether group, and has a general siloxane unit [—SiR 1 2-O-)], as well as siloxane units with polyether groups [—SiR 1 (R 2 O(R 3 O) n R 4 )-O-)]. where R 1 is one or more alkyl or aryl groups, R 2 and R 3 is one or more alkylene groups, R 4 indicates one or more alkyl groups, acyl groups, etc. (terminal groups). The polyether group is a polyoxyethylene group [(C2H4O) n In the siloxane unit having a polyether group, the terminal of the polyether group is an OH group (R in the above general formula). 4 =H).

[0058] The polyether-modified siloxane compound is preferably a polyether-modified siloxane compound having an HLB value of 6 to 12. The pressure-sensitive adhesive composition preferably contains the polyether-modified siloxane compound in an amount of 0.01 to 0.5 parts by weight, more preferably 0.02 to 0.35 parts by weight, and particularly preferably 0.02 to 0.25 parts by weight, per 100 parts by weight of the acrylic polymer. The HLB value is the hydrophilic-lipophilic balance (hydrophilic-lipophilic ratio) defined in, for example, JIS K3211 (surfactant terminology) or the like.

[0059] The polyether-modified siloxane compound can be obtained, for example, by grafting an organic compound having an unsaturated bond and a polyoxyalkylene group onto a polyorganosiloxane main chain having a silicon hydride group through a hydrosilylation reaction. Specific examples of the polyether-modified siloxane compound include dimethylsiloxane-methyl(polyoxyethylene)siloxane copolymer, dimethylsiloxane-methyl(polyoxyethylene)siloxane-methyl(polyoxypropylene)siloxane copolymer, and dimethylsiloxane-methyl(polyoxypropylene)siloxane polymer.

[0060] The polyether-modified siloxane compound can be blended in the pressure-sensitive adhesive composition to improve the adhesive strength and reworkability of the pressure-sensitive adhesive layer 2. The weight-average molecular weight of the polyether-modified siloxane compound is preferably 10,000 or less. Furthermore, from the viewpoint of compatibility with the acrylic polymer, the lower the HLB value and the lower the molecular weight of the polyether-modified siloxane compound, the better the compatibility. However, if the polyether-modified siloxane compound has a low molecular weight, it has a relatively high HLB value and can provide excellent antistatic properties even if its compatibility with the acrylic polymer is somewhat low.

[0061] The PSA composition of the present embodiment may contain, as appropriate, known additives such as surfactants, curing accelerators, plasticizers, fillers, curing retarders, processing aids, antioxidants, antioxidants, etc. These may be used alone or in combination of two or more.

[0062] The thickness of the pressure-sensitive adhesive layer 2 used in the antistatic surface protection film 10 according to this embodiment is not particularly limited, but is preferably about 5 to 40 μm, and more preferably about 10 to 30 μm.

[0063] It is preferable that the adhesive layer 2 has a weak adhesive strength, that is, the peel strength (adhesion strength) of the antistatic surface protection film to the surface of the adherend, of about 0.01 to 0.3 N / 25 mm, because this provides excellent operability when peeling the antistatic surface protection film from the adherend. In addition, in order to ensure excellent operability when peeling the release film 5 from the antistatic surface protection film 10, the peeling force of the release film 5 from the pressure-sensitive adhesive layer 2 is preferably 0.2 N / 50 mm or less.

[0064] Furthermore, the release film 5 used in the antistatic surface protection film 10 according to this embodiment has a release agent layer 4 formed on one side of the resin film 3 from a resin composition containing a release agent primarily composed of dimethylpolysiloxane, a silicone-based compound that is liquid at 20°C, and a second antistatic agent (K2).

[0065] Examples of the resin film 3 include polyester film, polyamide film, polyethylene film, polypropylene film, and polyimide film, but polyester film is particularly preferred because of its excellent transparency and relatively low price. The resin film 3 may be an unstretched film or a uniaxially or biaxially stretched film. The stretching ratio of the stretched film and the axial orientation angle formed by crystallization of the stretched film may be controlled to specific values. The thickness of the resin film 3 is not particularly limited, but is preferably about 12 to 100 μm, and more preferably about 20 to 50 μm, as this is easy to handle. 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.

[0066] 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. Examples of commercially available products as addition reaction type silicone release agents include 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, and LTC-310 (manufactured by Dow-Toray Industries, Inc.). Examples of commercially available products as condensation reaction type silicone release agents include SRX-290 and SYLOFF-23 (manufactured by Dow Toray Industries, Inc.). Examples of commercially available cationic polymerization silicone release agents include TPR-6501, TPR-6500, UV9300, VU9315, and UV9430 (manufactured by Momentive Performance Materials), and X62-7622 (manufactured by Shin-Etsu Chemical Co., Ltd.). Examples of commercially available radical polymerization type silicone release agents include X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0067] Examples of silicone compounds that are liquid at 20° C. and that constitute the release agent layer 4 include polyether-modified silicone, alkyl-modified silicone, and carbinol higher fatty acid ester-modified silicone. In this embodiment, in order to improve the antistatic properties of the surface of the pressure-sensitive adhesive layer 2, a release agent layer 4 in which a silicone compound that is liquid at 20°C is dissolved in a release agent whose main component is dimethylpolysiloxane is preferably used.

[0068] Among modified silicone compounds, polyether-modified silicones are preferred for use in this embodiment. The polyether chain in polyether-modified silicones is composed of ethylene oxide, propylene oxide, etc., and physical properties such as compatibility with silicone release agents and antistatic effect can be adjusted by selecting, for example, the molecular weight of the polyethylene oxide used in the side chain. In addition, examples of commercially available polyether-modified silicone products include KF-351A, KF-352A, KF-353, KF-354L, KF-355A, and KF-642 (manufactured by Shin-Etsu Chemical Co., Ltd.), SH8400, SH8700, and SF8410 (manufactured by Dow-Toray Industries, Inc.), TSF-4440, TSF-4441, TSF-4445, TSF-4446, and TSF-4450 (manufactured by Momentive Performance Materials), and BYK-300, BYK-306, BYK-307, BYK-320, BYK-325, and BYK-330 (manufactured by BYK-Chemie).

[0069] The amount of the silicone compound added to the release agent in the release agent layer 4 varies depending on the type of silicone compound and the degree of compatibility with the release agent. The amount added may be set taking into consideration the desired peel electrification voltage, stain resistance to the adherend, adhesive properties, etc. when peeling the antistatic surface protection film from the adherend.

[0070] The second antistatic agent (K2) constituting the release agent layer 4 is preferably one that has good dispersibility in the coating liquid that forms the release agent layer 4 and does not inhibit the hardening of the release agent. The second antistatic agent (K2) is preferably an alkali metal salt. Examples of the alkali metal salt include metal salts of lithium, sodium, and potassium. Specifically, for example, Li +, Na + , K. + and a cation consisting of Cl - , Br - , I - , BF4 - , PF6 - , SCN - , ClO4 - , CF3SO3 - , (FSO2)2N - , (CF3SO2)2N - , (C2F5SO2)2N - , (CF3SO2)3C - A metal salt composed of an anion consisting of the following is preferably used. The second antistatic agent (K2) is a Li salt, and is particularly preferably at least one selected from the group consisting of LiTFSI, LiFSI, and LiTF. Here, LiTFSI represents Li(CF3SO2)2N, LiFSI represents Li(FSO2)2N, and LiTF represents LiCF3SO3. The alkali metal salt of the second antistatic agent (K2) may be used alone or in combination of two or more. In order to stabilize the ionic substance, a compound containing a polyoxyalkylene structure may be added to the release agent layer 4.

[0071] The amount of the second antistatic agent (K2) added to the release agent layer 4 varies depending on the type of the second antistatic agent (K2) and the degree of affinity with the release agent, but may be set taking into consideration the desired peeling electrification voltage, contamination resistance to the adherend, adhesive properties, etc. when peeling the antistatic surface protective film from the adherend.

[0072] The method for preparing the coating liquid for forming the release agent layer 4 by mixing the release agent with the polyether-modified silicone and the second antistatic agent (K2) includes the following methods, but is not particularly limited. (1) A method in which the polyether-modified silicone and the second antistatic agent (K2) are added to the release agent and mixed, and then a catalyst for curing the release agent is added and mixed. (2) A method in which the release agent is diluted in advance with an organic solvent, and then the polyether-modified silicone, the second antistatic agent (K2), and the catalyst for curing the release agent are added and mixed. (3) A method in which the release agent is diluted in an organic solvent in advance, a catalyst is added and mixed, and then the polyether-modified silicone and the second antistatic agent (K2) are added and mixed. If necessary, an adhesion improver such as a silane coupling agent or a material that aids in the antistatic effect such as a compound containing a polyoxyalkylene group may be added to the coating liquid for forming the release agent layer 4.

[0073] There are no particular limitations on the mixing ratio of the release agent to the polyether-modified silicone and the second antistatic agent (K2). The weight ratio of the polyether-modified silicone and the second antistatic agent (K2) in terms of solid content is preferably about 5 to 100 parts by weight relative to 100 parts by weight of the solid content of the release agent. If the amount of polyether-modified silicone and second antistatic agent (K2) added in terms of solid content is less than 5 parts by weight per 100 parts by weight of the solid content of the release agent, the amount of second antistatic agent (K2) transferred to the surface of the pressure-sensitive adhesive layer 2 will also be small, making it difficult for the pressure-sensitive adhesive layer 2 to exhibit its antistatic function. It is also undesirable for the amount of polyether-modified silicone and second antistatic agent (K2) added in terms of solid content to exceed 100 parts by weight per 100 parts by weight of the solid content of the release agent, as this may result in the release agent being transferred to the surface of the pressure-sensitive adhesive layer 2 along with the polyether-modified silicone and second antistatic agent (K2), potentially reducing the adhesive properties of the pressure-sensitive adhesive layer 2.

[0074] The method for forming the adhesive layer 2 on the base film 1 of the antistatic surface protective film 10 according to this embodiment and the method for attaching the release film 5 may be performed by a known method and are not particularly limited, but the following method is used. (1) A method in which a resin composition for forming the adhesive layer 2 is applied to one side of the base film 1, dried to form the adhesive layer 2, and then a release film 5 is attached. (2) A method in which a resin composition for forming the adhesive layer 2 is applied to the surface of the release film 5 and dried to form the adhesive layer 2, and then the base film 1 is laminated.

[0075] The pressure-sensitive adhesive layer 2 and the antistatic layer 6 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.

[0076] The method for producing the antistatic surface protection film 10 of the embodiment may include the following steps (1) to (4). Step (1): A step of preparing the pressure-sensitive adhesive composition. Step (2): A step of forming a pressure-sensitive adhesive layer 2 on one surface of a substrate film 1 by crosslinking the pressure-sensitive adhesive composition. Step (3): A step of forming an antistatic layer 6 containing carbon nanotubes as a first antistatic agent (K1) on the other surface of the base film 1, which is the surface opposite to the one surface. Step (4): A step of laminating a release film 5 to the surface of the adhesive layer 2 via a release agent layer 4, and transferring the second antistatic agent (K2) in the release agent layer 4 to the surface of the adhesive layer 2.

[0077] The antistatic surface protection film 10 is preferably produced through steps (1) to (4) in this order. Step (3) may be carried out before step (1), between steps (1) and (2), or simultaneously with step (2). Step (3) may also be carried out after bonding the release film 5 to the surface of the pressure-sensitive adhesive layer 2 via the release agent layer 4 in step (4). Furthermore, when step (3) is carried out between step (2) and step (4), the adhesive layer 2 formed on one surface of the base film 1 may be exposed, or the adhesive layer 2 formed on one surface of the base film 1 may be protected by a release film or the like that does not contain an antistatic agent. Furthermore, the step of producing the release film 5 may be carried out in any order, regardless of the steps (1) to (3), as long as it is carried out before the step (4).

[0078] FIG. 2 is a cross-sectional view showing the antistatic surface protective film 11 in a state where the release film 5 has been peeled off from the antistatic surface protective film 10. As shown in FIG. By peeling off the release film 5 from the antistatic surface protection film 10 shown in Figure 1, a portion of the second antistatic agent (K2) 7 contained in the release agent layer 4 of the release film 5 is transferred (adhered) to the surface of the pressure-sensitive adhesive layer 2 of the antistatic surface protection film 11. Therefore, in FIG. 2, the second antistatic agent (K2) transferred to the surface of the pressure-sensitive adhesive layer 2 of the antistatic surface protection film 11 is shown schematically as spots indicated by the reference numeral 7. In addition, an antistatic layer 6 containing carbon nanotubes as a first antistatic agent (K1) is formed on the other surface of the base film 1 opposite to the surface on which the pressure-sensitive adhesive layer 2 is formed. In the antistatic surface protective films 10 and 11 according to this embodiment, when the antistatic surface protective film 11 in the state in which the release film shown in FIG. 2 has been peeled off is attached to an adherend, the second antistatic agent (K2) 7 transferred to the surface of the adhesive layer 2 comes into contact with the surface of the adherend. This makes it possible to keep the peeling electrification voltage low when the antistatic surface protective film 11 is peeled off from the adherend again. In addition to the second antistatic agent (K2) 7, a silicone-based compound that is liquid at 20°C may be transferred from the release agent layer 4 to the surface of the pressure-sensitive adhesive layer 2.

[0079] FIG. 3 is a cross-sectional view showing an example of the optical component of this embodiment. The release film 5 is peeled off from the antistatic surface protection film 10 according to this embodiment, leaving an antistatic surface protection film 11 with the pressure-sensitive adhesive layer 2 exposed, which is then attached to an optical component 8 as an adherend via the pressure-sensitive adhesive layer 2. An antistatic layer 6 containing carbon nanotubes as a first antistatic agent (K1) is formed on the other surface of the base film 1 opposite to the surface on which the pressure-sensitive adhesive layer 2 is formed. 3 shows an optical component 20 to which antistatic surface protective films 10 and 11 of the present embodiment are attached. Examples of the optical component 8 include optical films such as a polarizing plate, a retardation plate, a lens film, a polarizing plate that also serves as a retardation plate, and a polarizing plate that also serves as a lens film. Such optical components 8 are used as components of liquid crystal display devices such as liquid crystal display panels, optical devices for various instruments, etc. Other examples of the optical components 8 include optical films such as anti-reflection films, hard coat films, and transparent conductive films for touch panels.

[0080] The antistatic surface protective films 10 and 11 of this embodiment are particularly suitable for use on the anti-fouling treated surfaces of optical films such as low-reflection treated polarizing plates (LR polarizing plates) and anti-glare low-reflection treated polarizing plates (AG-LR polarizing plates), whose surfaces have been treated with silicone compounds, fluorine compounds, or the like to provide anti-fouling properties. According to the optical component 20 of this embodiment, when the antistatic surface protective films 10, 11 are peeled off and removed from the adherend, that is, the optical component (optical film), the peeling electrification voltage can be kept sufficiently low, so there is no risk of damaging circuit components such as driver ICs, TFT elements, and gate line driving circuits, and production efficiency in the process of manufacturing liquid crystal display panels, etc. can be improved and the reliability of the production process can be maintained.

[0081] The antistatic surface protective films 10 and 11 of the present embodiment are suitable as surface protective films for polarizing plates. The pressure-sensitive adhesive layer 2 of the antistatic surface protective films 10 and 11 may be attached to the protective layer of the polarizer of a polarizing plate. In applications where the surface protection film for polarizing plates is used, the protective layer of the polarizer of the polarizing plate to be adhered may be at least one selected from the group consisting of TAC film, PMMA film, and PET film, where TAC is an abbreviation for triacetyl cellulose, PMMA is an abbreviation for polymethyl methacrylate, and PET is an abbreviation for polyethylene terephthalate. In addition, the surface treatment applied to the surface of the protective layer of the polarizer of the polarizing plate, which serves as an adherend in the use of the surface protective film for polarizing plate, may be at least one selected from the group consisting of untreated, AG treatment, LR treatment, AR treatment, AG-LR treatment, and AG-AR treatment. Here, AG stands for anti-glare, LR stands for low reflection, and AR stands for anti-reflection.

[0082] In the antistatic surface protection films 10 and 11 of this embodiment, the surface resistivity of the pressure-sensitive adhesive layer 2 to which the second antistatic agent (K2) has been transferred from the release agent layer 4 is 1.0×10 +12 It is preferable that the resistance is Ω / □ or less, and 5.0×10 +11 It is more preferable that it is Ω / □ or less, and 1.0×10 +11 It is particularly preferable that the resistance is Ω / □ or less. If the surface resistivity of the pressure-sensitive adhesive layer 2 is high, the performance of dissipating static electricity generated when the pressure-sensitive adhesive layer 2 is peeled off from the adherend is poor. Therefore, by making the surface resistivity of the adhesive layer 2 sufficiently small, the peeling electrification voltage that occurs with the static electricity generated when the adhesive layer 2 is peeled from the adherend can be reduced, thereby suppressing the effect on the adherend.

[0083] In the antistatic surface protection films 10 and 11 of the present embodiment, an antistatic layer 6 containing carbon nanotubes as a first antistatic agent (K1) is formed on the other surface of the base film 1, which is opposite to the surface on which the pressure-sensitive adhesive layer 2 is formed. The initial surface resistivity of this antistatic layer 6 is 1.0×10 +10Ω / □ or less, and even after 90 days of exposure to the atmosphere at 23°C and 50% RH, the resistance is 1.0×10 +10 It is preferable to maintain the value at or below Ω / □. The change over time of conventional antistatic layers exposed to the atmosphere shows a tendency for the surface resistivity to gradually decrease. Therefore, the antistatic surface protection films 10 and 11 of the present embodiment were stored in an atmosphere of 23°C x 50% RH for 90 days while exposed to the atmosphere, and the surface resistivity of the antistatic layer 6 was measured at least once to be 1.0 x 10 +10 It is preferably Ω / □ or less.

[0084] In the antistatic surface protection films 10 and 11 of this embodiment, the adhesive layer 2 to which the second antistatic agent (K2) has been transferred from the release agent layer 4 preferably has a peeling electrification voltage in the range of +0.3 to −0.3 kV relative to a low refractive index layer formed using a composition for forming a low refractive index layer containing a fluorine compound. Examples of fluorine compounds used in the composition for forming the low refractive index layer include fluorine-containing copolymers, which are polymers of one or more of fluorinated olefins, fluorinated vinyl ethers, fluorinated alkyl (meth)acrylates, etc., and condensates of fluorinated alkyl group-containing silane compounds, etc. The fluorine-containing copolymers may be copolymerized with non-fluorinated monomers, such as olefins, vinyl ethers, and (meth)acrylates, in addition to fluorinated monomers. The low refractive index layer may be combined with a high refractive index layer, etc., to form an antireflection layer.

[0085] When measuring the peel electrification voltage for the low refractive index layer, examples of the substrate on which the low refractive index layer is formed include a PMMA substrate and a TAC substrate. Furthermore, in the antistatic surface protection films 10 and 11 of this embodiment, it is preferable that the adhesive layer 2 to which the second antistatic agent (K2) has been transferred from the release agent layer 4 has a peeling electrification voltage in the range of +0.3 to -0.3 kV relative to a plain layer on the surface of a PMMA substrate or a TAC substrate that has not been treated in any way.

[0086] It is preferable that the adhesive layer 2 is not contaminated when it is attached to an adherend such as a polarizing plate, left in an atmosphere at a temperature of 60°C and a humidity of 90% RH for 2 days (48 hours), removed from the atmosphere, and peeled off after 1 day has passed. Further, examples of the adherend include a polarizing plate in which a protective layer is laminated on a polarizer, and the surface of the protective layer is subjected to a low-reflection surface treatment with a composition containing a fluorine compound. The composition containing a fluorine compound used for the low-refractive-index surface treatment may be the same as or different from the resin composition containing a fluorine compound for forming the low-refractive-index layer described above. Examples of the protective layer and surface treatment include the protective layer of the polarizer described above and the surface treatment applied to the surface of the protective layer. Specifically, examples of such polarizing plates include a surface substrate that is one selected from the group consisting of a TAC-based film, a PMMA-based film, and a PET-based film, and the surface treatment applied to the surface of the surface substrate is one selected from the group consisting of untreated, AG treatment, LR treatment, AR treatment, AG-LR treatment, and AG-AR treatment.

[0087] In the antistatic surface protection films 10 and 11 of this embodiment, the adhesive strength of the adhesive layer 2 to an adherend can be evaluated by a method in which the adhesive layer 2 obtained by crosslinking the adhesive composition is laminated to a thickness of 15 μm on one side of a polyester film having a thickness of 38 μm, and then the antistatic surface protection film 11 obtained by transferring the second antistatic agent (K2) 7 from the release agent layer 4 to the surface of the adhesive layer 2 is bonded to the surface of a polarizing plate, which is an example of an adherend. Thereafter, when the antistatic surface protection film 11 is peeled off from the polarizing plate, the adhesive strength at a low peeling speed of 0.3 m / min is preferably 0.01 to 0.1 N / 25 mm, and at a high peeling speed of 30 m / min is preferably 1.0 N / 25 mm or less, and more preferably 0.2 to 0.8 N / 25 mm at a high peeling speed of 30 m / min. This results in a performance in which the adhesive strength changes little depending on the peeling speed, and even with high-speed peeling, it is possible to quickly peel off the antistatic surface protective film 11. Furthermore, even when the antistatic surface protective film 11 needs to be peeled off once for re-adhering, excessive force is not required, and it can be easily peeled off from the adherend.

[0088] In the antistatic surface protection films 10 and 11 of this embodiment, after crosslinking the pressure-sensitive adhesive composition, the gel fraction of the pressure-sensitive adhesive layer 2 to which the second antistatic agent (K2) is transferred from the release agent layer 4 is preferably 95 to 100%, more preferably 97 to 100%. Because the adhesive layer 2 has such a high gel fraction, the adhesive strength at low peel speeds is not excessive, the elution of unpolymerized monomers or oligomers from the adhesive layer 2 is reduced, reworkability and durability at high temperatures and high humidity are improved, and contamination of the adherend can be suppressed.

[0089] The pressure-sensitive adhesive film of the present embodiment is formed by forming a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition of the present embodiment on one or both sides of a resin film. The surface protection film of the present embodiment is formed by forming a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition of the present embodiment on one side of a resin film. The surface protection film of this embodiment becomes the antistatic surface protection film 10, 11 by transferring the second antistatic agent (K2) from the release agent layer 4 to the surface of the pressure-sensitive adhesive layer 2, and has excellent antistatic properties. Furthermore, the antistatic surface protection films 10, 11 of this embodiment have an excellent balance of adhesive strength at both low and high peel speeds, and also have stain resistance. Therefore, they can be suitably used as surface protection films for polarizing plates.

[0090] Furthermore, an optical film with a pressure-sensitive adhesive layer can be obtained by crosslinking the pressure-sensitive adhesive composition on at least one surface of the optical film and then laminating a pressure-sensitive adhesive layer 2 to which the second antistatic agent (K2) has been transferred from the release agent layer 4. Examples of optical films include polarizing films, retardation films, anti-reflection films, anti-glare films, ultraviolet absorbing films, infrared absorbing films, optical compensation films, and brightness enhancing films. Devices to which the optical components 8 and 20 are applied include liquid crystal panels, organic EL panels, touch panels, and the like. In the case of an optical surface protection film such as a surface protection film for a polarizing plate and an adhesive film, the base film 1 and the adhesive layer 2 preferably have sufficient transparency. [Example]

[0091] The present invention will be specifically described below with reference to examples.

[0092] <Production of coating solution for forming antistatic layer> [Examples 1 to 4, Comparative Example 4] As the first antistatic agent (K1), 5 parts by weight of commercially available multi-walled carbon nanotubes and 95 parts by weight of at least one hydroxyl group-containing polymer were dissolved in a solvent, and then the solution was stirred while applying ultrasonic vibrations to obtain a coating liquid for forming the antistatic layers of Examples 1 to 4 and Comparative Example 4.

[0093] Comparative Example 3 As an antistatic agent made of a conductive polymer, a mixture of polyaniline (manufactured by Nippon Shokubai Co., Ltd.) and polythiophene (manufactured by Teikoku Seiyaku Co., Ltd.) with a solids weight ratio of 10:90 was dissolved in a solvent to obtain a coating liquid for forming the antistatic layer of Comparative Example 3.

[0094] <Production of Pressure-Sensitive Adhesive Composition> [Example 1] Nitrogen gas was introduced into a reactor equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube, and the air in the reactor was replaced with nitrogen gas. Then, 80 parts by weight of 2-ethylhexyl acrylate (2EHA), 20 parts by weight of n-butyl acrylate (BA), 4.5 parts by weight of 8-hydroxyoctyl acrylate (8HOA), 10 parts by weight of polypropylene glycol monoacrylate (n = 12), and a solvent (ethyl acetate) were added to the reactor. Then, 0.1 parts by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise over 2 hours, and the mixture was allowed to react at 65 ° C for 6 hours, yielding an acrylic polymer solution of Example 1. To this acrylic polymer solution, 8.5 parts by weight of acetylacetone (AA) was added and stirred, and then 2.0 parts by weight of Coronate HX (an isocyanurate of a hexamethylene diisocyanate compound), 0.1 parts by weight of titanium trisacetylacetonate, and 0.05 parts by weight of a polyether-modified siloxane compound (HLB=7) were added and mixed with stirring to obtain the adhesive composition of Example 1.

[0095] [Examples 2 to 4 and Comparative Examples 1 to 4] The pressure-sensitive adhesive compositions of Examples 2 to 4 and Comparative Examples 1 to 4 were obtained in the same manner as Example 1, except that the formulation of the pressure-sensitive adhesive composition of Example 1 was changed to those shown in Table 1. In the case of the pressure-sensitive adhesive compositions of Comparative Examples 1 and 2, the compound shown in "Antistatic agent (pressure-sensitive adhesive layer)" in Table 2 was further added to the pressure-sensitive adhesive composition. The acrylic polymers of Examples 1 to 4 and Comparative Examples 1 to 3 were copolymers having a weight-average molecular weight of more than 300,000 and not more than 1,000,000. The acrylic polymer of Comparative Example 4 was a copolymer having a weight-average molecular weight of 100,000.

[0096] In each column of Table 1 and in the "Antistatic Agent (Adhesive Layer)" column of Table 2, the parts by weight of each component were calculated relative to 100 parts by weight of the total of (A) alkyl (meth)acrylates having a carbon number of C1 to C18 in the alkyl group. "(D) / (E)" in Table 2 indicates the ratio by weight. In addition, in each of columns (B) to (G) of Table 1, the content (parts by weight) of each component is shown in parentheses when the parts by weight of the acrylic polymer calculated as the sum of the parts by weight of (A), (B), and (F) is taken as 100 parts by weight. In addition, in the "Antistatic Agent (Adhesive Layer)" column of Table 2, LiTFSI represents Li(CF3SO2)2N, and LiTF represents LiCF3SO3.

[0097] [Table 1]

[0098] [Table 2]

[0099] The compound names of the abbreviations of the components (A) to (G) used in Table 1 are shown in Table 3. Coronate (registered trademark) HX, Coronate HL, and Coronate L are product names of Tosoh Corporation, and Takenate (registered trademark) D-140N and D-110N are product names of Mitsui Chemicals, Inc. Furthermore, among the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomers constituting the (F) polyalkylene glycol chain, F-1 to F-3 are monomers having a diester content of 0.2 wt% or less, and F-4 is a monomer having a diester content of 0.8 wt%. The value of n indicates the average repeat number of alkylene oxide. Furthermore, among the (G) polyether-modified siloxane compounds, G-1 to G-6 have a weight average molecular weight of 10,000 or less.

[0100] [Table 3]

[0101] <Preparation of antistatic surface protection film> [Example 1] A coating liquid for forming the release agent layer of Example 1 was prepared by combining 5 parts by weight of an addition reaction type silicone (manufactured by Dow Toray Industries, Inc., product name: SRX-345), 0.15 parts by weight of a polyether-modified silicone (manufactured by Dow Toray Industries, Inc., product name: SH8400), 0.5 parts by weight of lithium bis(trifluoromethanesulfonyl)imide salt (LiTFSI) as a second antistatic agent (K2), 95 parts by weight of a 1:1 mixed solvent of toluene and ethyl acetate, and 0.05 parts by weight of a platinum catalyst (manufactured by Dow Toray Industries, Inc., product name: SRX-212 catalyst), followed by stirring and mixing. The coating solution for forming the release agent layer of Example 1 was applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm using a Mayer bar so that the thickness after drying would be 0.2 μm, and the film was dried for 1 minute in a hot air circulating oven at 120°C to obtain the release film of Example 1. The pressure-sensitive adhesive composition of Example 1 was applied to one surface of a 38 μm-thick polyethylene terephthalate film used as a base film so as to give a dried thickness of 15 μm, and then dried for 2 minutes in a hot air circulating oven at 100° C. to form a pressure-sensitive adhesive layer. Furthermore, the coating liquid for forming the antistatic layer of Example 1 was applied to the other surface of the base film opposite the surface on which the pressure-sensitive adhesive layer was formed so as to give a dried thickness of 0.05 μm, and then dried for 2 minutes in a hot air circulating oven at 100° C. to form an antistatic layer. Thereafter, the release agent layer (silicone-treated surface) of the release film of Example 1 prepared above was attached to the surface of this pressure-sensitive adhesive layer. The resulting pressure-sensitive adhesive film was kept warm in an environment of 40°C for 5 days to cure the pressure-sensitive adhesive, thereby obtaining the antistatic surface protection film of Example 1.

[0102] [Examples 2 to 4] The coating solutions for forming the release agent layers of Examples 2 to 4 were prepared in the same manner as in Example 1, except that the compositions of the coating solutions for forming the release agent layers of Example 1 were each as shown in Table 4, and the release films of Examples 2 to 4 were obtained. In addition, the antistatic surface protection films of Examples 2 to 4 were obtained in the same manner as Example 1, except that the adhesive composition of Example 1 was replaced with the adhesive compositions of Examples 2 to 4, the dried thickness of the antistatic layer was set as shown in Table 5, and the release film of Example 1 was replaced with the release film of Examples 2 to 4, respectively.

[0103] [Comparative Example 1] 5 parts by weight of addition reaction type silicone (Dow Toray Industries, Inc., product name: SRX-345), 95 parts by weight of a 1:1 mixed solvent of toluene and ethyl acetate, and 0.05 parts by weight of platinum catalyst (Dow Toray Industries, Inc., product name: SRX-212 catalyst) were mixed and stirred to prepare a coating solution for forming the release agent layer of Comparative Example 1. The coating solution for forming the release agent layer of Comparative Example 1 was applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm using a Mayer bar so that the thickness after drying would be 0.2 μm, and the film was dried for 1 minute in a hot air circulating oven at 120°C to obtain the release film of Comparative Example 1. The pressure-sensitive adhesive composition of Comparative Example 1 was applied to one surface of a 38 μm-thick polyethylene terephthalate film as a base film so that the thickness after drying would be 15 μm, and then dried for 2 minutes in a hot air circulating oven at 100° C. to form a pressure-sensitive adhesive layer. Furthermore, no antistatic layer was formed on the other surface of the base film, which is the surface opposite to the one surface on which the pressure-sensitive adhesive layer was formed. Thereafter, the release agent layer (silicone-treated surface) of the release film of Comparative Example 1 prepared above was attached to the surface of this adhesive layer. The resulting adhesive film was kept warm in an environment of 40°C for 5 days to cure the adhesive, thereby obtaining an antistatic surface protection film of Comparative Example 1.

[0104] Comparative Example 2 An antistatic surface protection film of Comparative Example 2 was obtained in the same manner as Comparative Example 1, except that the adhesive composition of Comparative Example 1 was replaced with the adhesive composition of Comparative Example 2. [Comparative Examples 3 to 4] Coating solutions for forming the release agent layers of Comparative Examples 3 and 4 were prepared in the same manner as in Example 1, except that the compositions of the coating solutions for forming the release agent layers of Example 1 were each set as shown in Table 4, and the release films of Comparative Examples 3 and 4 were obtained. In addition, antistatic surface protection films of Comparative Examples 3 and 4 were obtained in the same manner as Example 1, except that the adhesive composition, coating liquid for forming the antistatic layer, and release film of Example 1 were replaced with the adhesive composition, coating liquid for forming the antistatic layer, and release film of Comparative Examples 3 and 4, respectively.

[0105] In the "second antistatic agent (K2)" in Table 4, LiTFSI represents Li(CF3SO2)2N, LiFSI represents Li(FSO2)2N, and LiTF represents LiCF3SO3. In addition, in the "first antistatic agent (K1)" in Table 5, CNT represents multi-walled carbon nanotubes, PANI represents polyaniline, and PEDOT represents poly(3,4-ethylenedioxythiophene), a type of polythiophene.

[0106] [Table 4]

[0107] [Table 5]

[0108] <Test method and evaluation> The antistatic surface protection films of Examples 1 to 4 and Comparative Examples 1 to 4 were each aged for 7 days in an atmosphere at a temperature of 23°C and a humidity of 50%RH, and then evaluated by the following test methods. In the antistatic surface protection films of Examples 1 to 4 and Comparative Examples 3 and 4, the second antistatic agent (K2) can be transferred from the release agent layer to the surface of the pressure-sensitive adhesive layer by peeling off the release film. In the antistatic surface protection films of Comparative Examples 1 and 2, the compound shown in "Antistatic agent (pressure-sensitive adhesive layer)" in Table 2 is contained throughout the entire pressure-sensitive adhesive layer.

[0109] <Adhesive strength test method> The release film was peeled off to expose a 15 μm thick adhesive layer, and the antistatic surface protection film was then attached to the surface of a polarizing plate via the adhesive layer. After leaving it for one day, it was autoclaved at 50°C and 5 atmospheres for 20 minutes and then left at room temperature for another 12 hours to prepare a sample for measuring adhesive strength. The resulting sample was peeled in the 180° direction using a tensile tester at a low speed (0.3 m / min) or a high speed (30 m / min), and the peel strength was measured and used as the adhesive strength. Here, the protective layer of the polarizer of the polarizing plate is polymethyl methacrylate (PMMA) having an AG-LR treated layer.

[0110] <Surface resistivity test method> After aging the antistatic surface protection film, and before bonding it to a polarizing plate, the release film was peeled off to expose the adhesive layer, and the surface resistivity of the adhesive layer was measured using a resistivity meter, Hiresta (registered trademark) UP-HT450 (manufactured by Mitsubishi Chemical Analytech). Similarly, the initial surface resistivity of the antistatic layer was measured. The antistatic surface protection film was also stored in an atmosphere of 23° C.×50% RH for 90 days while being exposed to the air, and the surface resistivity of the antistatic layer after 90 days was measured.

[0111] <Test method for peeling electrification voltage> The release film was peeled off to expose the pressure-sensitive adhesive layer, and the antistatic surface protection film was then attached to a polarizing plate having a low refractive index layer formed on the adherend surface using a composition for forming a low refractive index layer containing a fluorine compound.The antistatic surface protection film was peeled off at an angle of 180° at a tensile speed of 30 m / min, and the voltage (charged voltage) generated by charging the adherend was measured using high-precision static electricity sensors SK-035 and SK-200 (manufactured by Keyence Corporation).The maximum measured value was taken as the peeling charged voltage.

[0112] <Test method for stain resistance> A polarizing plate having the surface substrate and surface treatment shown in Table 7 (untreated for Plain) was bonded to one side of a glass plate using a laminator via a pressure-sensitive adhesive layer (double-sided pressure-sensitive adhesive tape). The release film was then peeled off to expose the pressure-sensitive adhesive layer, and an antistatic surface protection film was then bonded to the surface of the polarizing plate using a laminator. After bonding to the adherend, the plate was left in an atmosphere of 60°C and 90% RH for 2 days (48 hours). After removal from the atmosphere, the antistatic surface protection film was peeled off and the surface of the polarizing plate was visually inspected for contamination. The stain resistance was evaluated as follows: no staining on the polarizing plate surface was evaluated as "Good," slight staining was evaluated as "Good," and significant staining was evaluated as "Poor."

[0113] Tables 6 to 7 show the evaluation results for the antistatic surface protection films of Examples 1 to 4 and Comparative Examples 1 to 4. The "surface resistivity" in Table 6 is expressed in the format of "m×10+n" as "mE+n" (where m is any real number and n is a positive integer).

[0114] [Table 6]

[0115] [Table 7]

[0116] The antistatic surface protection films of Examples 1 to 4 had an initial surface resistivity of 1.0 × 10 +10 Ω / □ or less, and the antistatic layer has a resistance of 1.0×10 even when exposed to the atmosphere at 23°C and 50% RH for 90 days. +10 A value of Ω / □ or less is maintained. Furthermore, the antistatic surface protection films of Examples 1 to 4 had adhesive strengths of 0.01 to 0.1 N / 25 mm at a low peel speed of 0.3 m / min to a polarizing plate as an adherend, and adhesive strengths of 1.0 N / 25 mm or less at a high peel speed of 30 m / min, demonstrating excellent adhesive performance by achieving a balance between adhesive strengths at low and high peel speeds. In addition, in the antistatic surface protection films of Examples 1 to 4, the antistatic agent in the release agent layer is transferred to the surface of the pressure-sensitive adhesive layer, so the surface resistivity of the pressure-sensitive adhesive layer is 1.0 × 10 +12 The peeling voltage of the adhesive layer relative to a low refractive index layer formed using a composition for forming a low refractive index layer containing a fluorine compound was in the range of +0.3 to -0.3 kV, demonstrating excellent antistatic performance. Furthermore, the antistatic surface protection films of Examples 1 to 4 were attached to an adherend, and then left in an atmosphere of 60°C and 90% RH for 48 hours. Even after being removed from the atmosphere and one day had passed, no contamination occurred on the adherend, i.e., various polarizing plates, and the films also had excellent contamination resistance. That is, the evaluation results shown in Tables 6 and 7 demonstrate that the antistatic surface protection films of Examples 1 to 4 were able to solve all of the problems of the present invention.

[0117] In the antistatic surface protection films of Comparative Examples 1 and 2, no antistatic layer containing the other antistatic agent is formed on the surface of the substrate film, and the surface resistivity of the other surface of the substrate film is extremely high. Furthermore, the antistatic surface protection film of Comparative Example 1 (in which the Tg of n-butyl acrylate (BA), a monofunctional alkyl (meth)acrylate monomer copolymerized with an acrylic polymer, is less than 0°C, the entire pressure-sensitive adhesive layer contains an antistatic agent, and the release agent layer does not contain a silicone-based compound that is liquid at 20°C or an antistatic agent) had slightly poor contamination resistance. Furthermore, the antistatic surface protection film of Comparative Example 2 (in which the monofunctional alkyl(meth)acrylate monomer and hydroxyl group-containing monomer copolymerized with the acrylic polymer were in excess, the acrylic polymer did not contain the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer that constitutes the polyalkylene glycol chain, the entire pressure-sensitive adhesive layer contained an antistatic agent, and the release agent layer did not contain the silicone compound that was liquid at 20°C or the antistatic agent) had high adhesive strength, high peeling electrification voltage, and poor contamination resistance. In addition, the antistatic surface protection film of Comparative Example 3 has an antistatic layer containing a conductive polymer as an antistatic agent formed on the surface of the substrate film. Therefore, the initial surface resistivity of the antistatic layer formed on the surface of the substrate film is 1.0 × 10 +10 However, when exposed to the atmosphere at 23°C and 50% RH for 90 days, the surface resistivity of the antistatic layer is 1.0×10 +10 Exceeds the Ω / □ value. Furthermore, the antistatic surface protection film of Comparative Example 3 (in which the acrylic polymer does not contain an alkyl(meth)acrylate monomer having a Tg of 0°C or higher and a polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer constituting a polyalkylene glycol chain, but contains a carboxyl group-containing monomer) had high adhesive strength, a high surface resistivity of the adhesive layer, a high peeling electrification voltage, and poor contamination resistance. Furthermore, the antistatic surface protection film of Comparative Example 4 (in which the weight-average molecular weight of the acrylic polymer is small) had poor stain resistance. As described above, the antistatic surface protection films of Comparative Examples 1 to 4 could not solve the problems of the present invention. [Explanation of symbols]

[0118] 1...base film, 2...adhesive layer, 3...resin film, 4...release agent layer, 5...release film, 6...antistatic layer containing first antistatic agent (K1), 7...second antistatic agent (K2), 8...adherend (optical component), 10...antistatic surface protective film, 11...antistatic surface protective film from which the release film has been peeled off, 20...optical component to which the antistatic surface protective film has been attached.

Claims

1. A method for producing an antistatic surface protective film, comprising the following steps (1) to (4): Step (1): A step of preparing a pressure-sensitive adhesive composition containing an acrylic polymer and a crosslinking agent, wherein the acrylic polymer is an acrylic polymer consisting of a copolymer having a weight-average molecular weight of more than 300,000 and not more than 1,000,000, obtained by copolymerizing 100 parts by weight of at least one alkyl (meth)acrylate (A) having a carbon number of C1 to C18 in the alkyl group and 1.0 to 6.0 parts by weight of at least one copolymerizable monomer (B) having a hydroxyl group, without containing a copolymerizable monomer having a carboxyl group; Step (2): forming a pressure-sensitive adhesive layer by crosslinking the pressure-sensitive adhesive composition on one surface of a substrate film made of a transparent resin; Step (3): forming an antistatic layer containing only carbon nanotubes and a hydroxyl group-containing polymer as a first antistatic agent (K1) on the other surface of the base film, the other surface being opposite to the one surface; Step (4): A step of bonding a release film, which has a resin film and a release agent layer containing a second antistatic agent (K2) laminated on one side thereof, to the surface of the pressure-sensitive adhesive layer via the release agent layer, thereby transferring the second antistatic agent (K2) in the release agent layer to the surface of the pressure-sensitive adhesive layer; is produced through steps (1) to (4) in this order, A method for producing an antistatic surface protective film, characterized in that an adhesive layer obtained by crosslinking the adhesive composition is laminated to a thickness of 15 μm on one side of a polyester film having a thickness of 38 μm, and the second antistatic agent (K2) is transferred to the surface of the adhesive layer to form an antistatic surface protective film, which is then bonded to the surface of a polarizing plate, and the antistatic surface protective film exhibits an adhesive strength of 0.01 to 0.1 N / 25 mm at a low peeling speed of 0.3 m / min and an adhesive strength of 1.0 N / 25 mm or less at a high peeling speed of 30 m / min.

2. The initial surface resistivity of the antistatic layer on the surface of the base film is 1.0×10 ＋１０ Ω / □ or less, and the surface resistivity of the antistatic layer after storage in an atmosphere of 23° C. and 50% RH for 90 days in a state exposed to the air is 1.0×10 ＋１０ 2. The method for producing an antistatic surface protective film according to claim 1, wherein the surface resistivity is Ω / □ or less.

3. 3. The method for producing an antistatic surface protective film according to claim 1, wherein the acrylic polymer contains (F) a polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer that constitutes a polyalkylene glycol chain.

4. 4. The method for producing an antistatic surface protective film according to claim 1, wherein the second antistatic agent (K2) is an alkali metal salt.

5. An antistatic surface protection film comprising a substrate film made of a transparent resin and a pressure-sensitive adhesive layer formed on one surface thereof, the pressure-sensitive adhesive layer being formed by crosslinking a pressure-sensitive adhesive composition containing an acrylic polymer and a crosslinking agent, The acrylic polymer (A) 100 parts by weight of at least one alkyl (meth)acrylate having an alkyl group with a carbon number of C1 to C18; (B) 1.0 to 6.0 parts by weight of at least one copolymerizable monomer containing a hydroxyl group; an acrylic polymer comprising a copolymer having a weight average molecular weight of more than 300,000 and not more than 1,000,000, obtained by copolymerizing the above without containing a copolymerizable monomer having a carboxyl group, an antistatic layer containing only carbon nanotubes and a hydroxyl group-containing polymer as a first antistatic agent (K1) formed on the other surface of the base film, the other surface being opposite to the one surface; a release film, which comprises a resin film and a release agent layer containing a second antistatic agent (K2) laminated on one surface of the resin film, is bonded to the surface of the pressure-sensitive adhesive layer via the release agent layer, and the second antistatic agent (K2) in the release agent layer is transferred to the surface of the pressure-sensitive adhesive layer, An antistatic surface protective film, characterized in that an adhesive layer obtained by crosslinking the adhesive composition is laminated to a thickness of 15 μm on one side of a polyester film having a thickness of 38 μm, and the second antistatic agent (K2) is transferred to the surface of the adhesive layer, is bonded to the surface of a polarizing plate, and then the antistatic surface protective film is peeled from the polarizing plate, and the adhesive strength at a low peeling speed of 0.3 m / min is 0.01 to 0.1 N / 25 mm, and the adhesive strength at a high peeling speed of 30 m / min is 1.0 N / 25 mm or less.

6. 6. The antistatic surface protective film according to claim 5, wherein the acrylic polymer contains (F) a polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer that constitutes the polyalkylene glycol chain.

7. 7. The antistatic surface protective film according to claim 5, wherein the second antistatic agent (K2) is an alkali metal salt.

8. An antistatic surface protective film used as a surface protective film for polarizing plates, The antistatic surface protective film according to any one of claims 5 to 7, wherein the protective layer of the polarizer of the polarizing plate is one selected from the group consisting of a TAC-based film, a PMMA-based film, and a PET-based film, and the surface treatment applied to the surface of the protective layer of the polarizer of the polarizing plate is one selected from the group consisting of untreated, AG treatment, LR treatment, AR treatment, AG-LR treatment, and AG-AR treatment.

9. The antistatic surface protective film according to any one of claims 5 to 8, wherein the (B) hydroxyl group-containing copolymerizable monomer is at least one selected from the group consisting of 8-hydroxyoctyl(meth)acrylate, 6-hydroxyhexyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and N-hydroxyethyl(meth)acrylamide.

10. The antistatic surface protective film according to any one of claims 5 to 9, characterized in that the pressure-sensitive adhesive composition contains 0.01 to 0.5 parts by weight of a polyether-modified siloxane compound having an HLB value of 6 to 12 and a weight-average molecular weight of 10,000 or less, relative to 100 parts by weight of the acrylic polymer.

11. the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer has an average repeat number of alkylene oxides constituting the polyalkylene glycol chain of 3 to 14, the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer has a diester content of 0.2% or less, The antistatic surface protective film according to claim 6, characterized in that the polyalkylene glycol chain-containing mono(meth)acrylic acid ester monomer is at least one selected from the group consisting of polyalkylene glycol mono(meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, and ethoxypolyalkylene glycol (meth)acrylate, in an amount of 1 to 50 parts by weight per 100 parts by weight of the acrylic polymer.

12. The antistatic surface protective film according to any one of claims 5 to 11, characterized in that the second antistatic agent (K2) is a Li salt and is at least one selected from the group consisting of LiTFSI, LiFSI, and LiTF.

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