Method for producing antistatic surface-protective film, and antistatic surface-protective film

Abstract

This invention provides a method for manufacturing an antistatic surface protective film and the antistatic surface protective film itself. The antistatic layer formed on the surface of the substrate has excellent atmospheric exposure, thus being effective for long-term preservation. Furthermore, when the adhesive layer is peeled off, it maintains a balanced adhesive force at both low and high peeling speeds, while exhibiting excellent antistatic and anti-fouling properties. An antistatic surface protective film 10 is formed by forming an adhesive layer 2, which is cross-linked with an adhesive composition containing an acrylic polymer and a cross-linking agent, on one surface of a substrate film 1 made of a transparent resin. An antistatic layer 6 containing carbon nanotubes as a first antistatic agent (K1) is formed on the other surface of the substrate film 1. A release film 5, which has a release agent layer 4 containing a second antistatic agent (K2) on a single-area layer of a resin film 3, is adhered to the surface of the adhesive layer 2 via the release agent layer 4.

Description

[Technical Field]

[0001] This invention relates to a surface protective film used in the manufacturing process of optical components constituting liquid crystal displays (LCDs), organic EL display devices, etc. More specifically, this invention relates to a method for manufacturing an antistatic surface protective film for protecting the surface of optical components such as polarizing plates and retarders by attaching it to the surface of such components constituting liquid crystal displays, etc., and to the antistatic surface protective film itself. [Previous Technology]

[0002] Traditionally, to prevent damage or stains during the manufacturing process of optical components, a surface protective film with an adhesive layer on one side of the substrate film is commonly used. The surface protective film is attached to optical components, such as optical films, by means of a micro-adhesive adhesive layer. The adhesive layer needs to have micro-adhesive so that the used surface protective film can be easily peeled off from the surface of the optical film, and so that the adhesive does not adhere to or remain on the optical film of the adhered product (i.e., to prevent the occurrence of adhesive residue).

[0003] Furthermore, as a prior art, a technique has been disclosed in which an antistatic layer is deposited on the surface of a substrate (polyester film) of a surface protective film for optical components, and a conductive polymer is used as an antistatic agent contained in the antistatic layer (for example, Patent Documents 1 to 3). Some techniques using such conductive polymers are still in use today. However, if the surface protective film containing conductive polymers in the antistatic layer is stored in the atmospheric environment for a long period, there is a problem that the surface resistivity of the antistatic layer will increase over time, thereby reducing the antistatic performance (so-called poor atmospheric exposure).

[0004] Furthermore, in recent years, in addition to the triacetyl cellulose (TAC) used previously, materials that easily generate peeling static electricity when the surface protective film of the polarizer is peeled off, such as acrylic resins like polymethyl methacrylate (PMMA), polyester resins like polyethylene terephthalate (PET), cyclic olefin polymers, and polycarbonate (for example, Patent Document 4), are being increasingly used for the protective layer (sometimes also called protective film) of the polarizer, which is a type of optical component. Therefore, the antistatic properties required for the adhesive layer used for the surface protective film of the polarizer need to be superior to those of the past. Here, TAC is an abbreviation for cellulose triacetyl acrylate, PMMA is an abbreviation for polymethyl methacrylate, and PET is an abbreviation for polyethylene terephthalate. Furthermore, in applications involving surface protective films for polarizing plates, the surface treatment performed on the surface of the polarizer, which serves as a protective layer for the polarizing plate onto which the material is adhered, includes various surface treatments such as 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.

[0005] Thus, in recent years, surface protective films for polarizing plates have needed to address the situation where a variety of materials are used as protective layers for polarizing mirrors, which are the adhered polarizing plates. Furthermore, as surface protective films for optical components are increasingly used in various manufacturing processes, the proportion of processes where the surface protective film is attached to the optical component and stored for a long period is also increasing. In addition, even after the manufacturing process of the optical component is completed, the opportunity for long-term storage with the surface protective film attached to the optical component until the manufactured optical component is installed in a device such as a liquid crystal display (LCD) is also increasing.

[0006] [Prior Art Documents] [Patent Document 1] Japanese Patent Application Publication No. 2006-169455 [Patent Document 2] Japanese Patent Application Publication No. 2004-338379 [Patent Document 3] Japanese Patent Application Publication No. 2004-223923 [Patent Document 4] Japanese Patent Application Publication No. 2017-165086 [Summary of the Invention]

[0007] As described above, in the prior art, if the surface protective film containing conductive polymers in the antistatic layer is stored in the atmospheric environment for a long time, the antistatic performance of the antistatic layer will decrease over time, which is already obvious. However, no technology has been found that can solve this problem. In addition, in the recent surface protective films, in the step of peeling them off from each substrate after they are adhered to various materials, it is required that the adhesion at both high-speed peeling speed and low-speed peeling speed is within a predetermined adhesion range. Furthermore, the adhesive layer is required to have excellent antistatic properties and resistance to contamination of the substrate.

[0008] The present invention was made in view of the above circumstances, and its object is to provide a method for manufacturing an antistatic surface protective film and an antistatic surface protective film, wherein the antistatic layer formed on the surface of the substrate has excellent atmospheric exposure, thus being effective for long-term preservation, and, when the adhesive layer is peeled off, it maintains a balanced adhesive force at both low and high peeling speeds, while the adhesive layer exhibits excellent antistatic and anti-fouling properties.

[0009] The inventors conducted in-depth research to solve these problems. First, although the reason why the surface resistivity of the antistatic layer, containing a conductive polymer, would increase over time and thus reduce its antistatic performance (so-called poor atmospheric exposure) when the surface protective film of the antistatic layer is stored in the atmospheric environment for a long time is unclear, it is speculated that this is because the conductive polymer is oxidized and degraded by moisture and oxygen in the atmosphere. Therefore, after searching for materials that are not oxidized and degraded by moisture and oxygen in the atmosphere and have high total light transmittance and conductivity, the problem was finally solved by using carbon nanotubes as the antistatic agent (K1) in the antistatic layer.

[0010] Further, regarding another problem, a solution is provided for obtaining an antistatic surface protective film that maintains a balanced adhesive force at both low and high peeling speeds while exhibiting excellent antistatic and anti-fouling properties of the adhesive layer during peeling. To solve this problem, in the adhesive composition used to form the adhesive layer of the antistatic surface protective film of the present invention, the acrylic polymer contained in the adhesive composition is an acrylic polymer formed by copolymerization of a copolymer having a weight average molecular weight of more than 300,000 and less than 1,000,000, wherein the copolymer is formed by copolymerization of at least 100 parts by weight of at least one (A) alkyl methacrylate with a carbon number of C1 to C18 and at least 1.0 to 6.0 parts by weight of 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, and an adhesive layer is deposited, an appropriate amount of a silicone compound that is liquid at 20°C and a second antistatic agent (K2) are applied to the surface of the adhesive layer, thereby reducing the contamination of the adhered object (having contamination resistance) and reducing the peeling electrostatic voltage when peeling off the optical film that is the adhered object, thus solving the problem.

[0011] In addition, in order to solve the above-mentioned technical problems, the present invention provides a method for manufacturing an antistatic surface protective film, characterized in that the manufacturing method includes preparation in the order of steps (1) to (4): Step (1): the step of preparing an adhesive composition, wherein the adhesive composition contains an acrylic polymer and a crosslinking agent, wherein the acrylic polymer is an acrylic polymer formed by copolymerization of a copolymer having a weight average molecular weight of more than 300,000 and less than 1,000,000, wherein the copolymer is copolymerized by copolymerization of at least 100 parts by weight of (A) alkyl methacrylate with a carbon number of C1 to C18 and at least 1.0 to 6.0 parts by weight of (B) a copolymerizable monomer containing a hydroxyl group, in a manner that does not contain a copolymerizable monomer having a carboxyl group, wherein the adhesive composition contains (C) a trifunctional or higher isocyanate compound as the crosslinking agent, further contains (D) a crosslinking delay agent and (E) a crosslinking accelerator other than a tin compound as the crosslinking accelerator; Step (2): forming an adhesive layer crosslinked with the adhesive composition on one surface of a substrate film formed of a transparent resin; Step (3): forming an antistatic layer containing carbon nanotubes as a first antistatic agent (K1) on another surface of the substrate film opposite to the first surface; and Step (4): attaching a release film containing a release agent layer containing a second antistatic agent (K2) on a single area layer of the resin film to the surface of the adhesive layer via the release agent layer, and transferring the second antistatic agent (K2) of the release agent layer to the surface of the adhesive layer, wherein the release agent layer is formed by a resin composition comprising a release agent mainly composed of dimethyl polysiloxane, a silicone compound that is liquid at 20°C, and the second antistatic agent (K2).

[0012] Furthermore, preferably, after an antistatic surface protective film is formed by depositing an adhesive layer of crosslinked adhesive composition with a thickness of 15 μm on one side of a polyester film with a thickness of 38 μm and transferring the second antistatic agent (K2) to the surface of the adhesive layer, and then attaching the antistatic surface protective film to the surface of a polarizing plate, when the antistatic surface protective film is peeled off from the polarizing plate, the adhesion is 0.01 N / 25 mm to 0.1 N / 25 mm at a low peeling speed of 0.3 m / min, and the adhesion is 1.0 N / 25 mm or less at a high peeling speed of 30 m / min.

[0013] Preferably, the initial surface resistivity of the antistatic layer on the surface of the substrate film is less than 1.0×10+10Ω / □, and the surface resistivity of the antistatic layer after being stored for 90 days in an environment exposed to the atmosphere at 23°C and 50%RH is less than 1.0×10+10Ω / □.

[0014] Preferably, at least one of the adhesive composition or the acrylic polymer contains (F) a mono(meth)acrylate monomer that constitutes a polyalkylene glycol chain.

[0015] Preferably, the second antistatic agent (K2) is an alkali metal salt.

[0016] Furthermore, the present invention provides an antistatic surface protective film, wherein the antistatic surface protective film is formed by forming an adhesive layer on a surface of a substrate film formed of a transparent resin, the adhesive layer being formed by crosslinking an adhesive composition containing an acrylic polymer and a crosslinking agent, characterized in that the acrylic polymer is an acrylic polymer formed by copolymerizing a copolymer having a weight average molecular weight of more than 300,000 and less than 1,000,000, wherein the copolymer is copolymerized by copolymerizing at least 100 parts by weight of at least one (meth)acrylate with an alkyl group having a carbon number of C1 to C18 and at least 1.0 to 6.0 parts by weight of at least one copolymerizable monomer containing a hydroxyl group, without containing a copolymerizable monomer having a carboxyl group, and the adhesive composition contains (C) an isocyanate compound with a trifunctional group or higher as the crosslinking agent, further containing (D) a crosslinking retarder and (E) a crosslinking accelerator other than a tin compound as the crosslinking accelerator. An antistatic layer containing carbon nanotubes as a first antistatic agent (K1) is formed on the other surface of the substrate film, which is opposite to the first surface. A release film containing a second antistatic agent (K2) is attached to the surface of the adhesive layer via the release agent layer, and the second antistatic agent (K2) of the release agent layer is transferred to the surface of the adhesive layer. The release agent layer is formed by a resin composition comprising a release agent with dimethyl polysiloxane as the main component, a silicone compound that is liquid at 20°C, and the second antistatic agent (K2).

[0017] In addition, preferably, at least one of the adhesive composition or the acrylic polymer comprises (F) a mono(meth)acrylate monomer containing a polyalkylene glycol chain constituting a polyalkylene glycol chain.

[0018] Preferably, the second antistatic agent (K2) is an alkali metal salt.

[0019] Preferably, the antistatic surface protective film is used as a surface protective film for a polarizing plate, the protective layer of the polarizing lens of the polarizing plate is selected from the group consisting of TAC film, PMMA film, and PET film, and the surface treatment performed on the surface of the protective layer of the polarizing lens of the polarizing plate is selected from the group consisting of untreated, AG treated, LR treated, AR treated, AG-LR treated, and AG-AR treated.

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

[0021] Preferably, the (D) crosslinking retarder is a keto-enol tautomer compound, and contains the (D) crosslinking retarder in a ratio of 0.1 parts by weight 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 selected from the group consisting of aluminum chelate compounds, titanium chelate compounds, and iron chelate compounds, and contains the (E) crosslinking accelerator in a ratio of 0.001 parts by weight to 0.5 parts by weight relative to 100 parts by weight of the acrylic polymer; the weight ratio of (D) to (E) is 80 to 1000.

[0022] Preferably, relative to 100 parts by weight of the acrylic polymer, the adhesive composition contains a polyether-modified siloxane compound with an HLB value of 6 to 12 and a weight average molecular weight of less than 10,000 in a ratio of 0.01 to 0.5 parts by weight.

[0023] Preferably, the average repeat number of alkylene oxide constituting the polyalkylene glycol chain in the mono(meth)acrylate monomer containing the polyalkylene glycol chain is 3 to 14, the diester component of the mono(meth)acrylate monomer containing the polyalkylene glycol chain is 0.2% or less, and in 100 parts by weight of the acrylic polymer, it contains at least one of the group consisting of polyalkylene glycol mono(meth)acrylate, methoxy polyalkylene glycol (meth)acrylate, and ethoxy polyalkylene glycol (meth)acrylate as the mono(meth)acrylate monomer containing the polyalkylene glycol chain in a proportion of 1 to 50 parts by weight.

[0024] Preferably, the silicone compound is a polyether-modified silicone.

[0025] Preferably, the second antistatic agent (K2) is a Li salt, and is 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 achieve the following effects (1) to (3). (1) The antistatic surface protective film of the present invention can provide an antistatic layer formed on the surface of the substrate with excellent atmospheric exposure, thus providing an effective antistatic surface protective film for long-term preservation. (2) The antistatic surface protective film of the present invention can provide an antistatic surface protective film that maintains a balanced adhesive force at both low and high peeling speeds when peeling off the adhesive layer. (3) The antistatic surface protective film of the present invention causes less contamination to the adhered object, and its contamination resistance to the adhered object does not change over time. Furthermore, according to the present invention, an antistatic surface protective film can be provided such that even if the surface of the antistatic protective film side of the substrate such as an LR polarizing plate or an AG-LR polarizing plate is an optical film that has been treated with anti-fouling agents such as silicone compounds or fluorine compounds, the peeling electrostatic voltage generated when the antistatic surface protective film with the release film peeled off is peeled off from the substrate is suppressed to be low, and it does not deteriorate over time and has excellent peeling antistatic performance.

Implementation Method

[0028] Hereinafter, the present invention will be described in detail based on embodiments. FIG1 is a cross-sectional view showing the concept of the antistatic surface protective film of this embodiment. In the antistatic surface protective film 10, an adhesive layer 2 is formed on one surface of a transparent substrate film 1. A release film 5, on which a release agent layer 4 is formed on the surface of a resin film 3, is adhered to the surface of the adhesive layer 2. Furthermore, an antistatic layer 6 containing carbon nanotubes as a first antistatic agent (K1) is formed on another surface of the transparent substrate film 1, which is opposite to the first surface. In addition, a release agent layer 4 containing a second antistatic agent (K2) is deposited in the release film 5.

[0029] As the substrate film 1 used in the antistatic surface protective film 10 according to this embodiment, a substrate film formed of a resin having transparency and flexibility is suitably used. This allows for the appearance inspection of the optical component while the antistatic surface protective film is adhered to the optical component as the adhered object. The transparent resin film used as the substrate film 1 can suitably be a polyester film such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, or polybutylene terephthalate. Besides polyester films, films formed of other resins can also be used, as long as they have the required strength and optical adaptability. The substrate film 1 can be an unstretched film or a film stretched uniaxially or biaxially. Furthermore, the stretch ratio of the stretched film and the alignment angle in the axial direction formed during the crystallization of the stretched film can be controlled to specific values.

[0030] The thickness of the substrate film 1 used in the antistatic surface protective film 10 according to this embodiment is not particularly limited. For example, a thickness of about 12 μm to 100 μm is preferred, and a thickness of about 20 μm to 50 μm is easier to handle and is even better. In addition, as needed, an anti-fouling layer to prevent surface contamination and a hard coating to prevent damage may be provided on the other surface of the substrate film 1 in addition to the antistatic layer 6. In addition, one or the other surface of the substrate film 1 may be subjected to surface modification based on corona discharge, coating of an anchor coating agent, or other easy-to-adhere treatments.

[0031] Furthermore, the antistatic layer 6 formed in the antistatic surface protective film 10 according to this embodiment contains carbon nanotubes as the first antistatic agent (K1). However, carbon nanofibers are widely known as conductive materials, but ordinary carbon nanofibers have a high light absorption rate in the visible light region, resulting in a decrease in transmittance. On the other hand, since the carbon nanotubes used in the antistatic layer 6 of this embodiment have a hollow molecular structure, it is possible to appropriately impart conductivity to the antistatic layer 6 while maintaining a high total light transmittance. That is, since the carbon nanotubes as the first antistatic agent (K1) have excellent conductivity, the content of carbon nanotubes in the antistatic layer 6 can be made to a lower concentration. In this way, an antistatic layer 6 with high total light transmittance and excellent antistatic performance can be obtained, and the antistatic performance of the antistatic layer 6 is stable when heated and humidified, so it can be used more efficiently.

[0032] The carbon nanotubes used as the first antistatic agent (K1) can also be carbon nanotubes manufactured by known manufacturing methods such as catalyst-supported vapor phase growth, vapor phase flow, and arc discharge. Specific examples include monolayer or multilayer carbon nanotubes with an average diameter of 0.3 nm to 100 nm. Furthermore, since multilayer carbon nanotubes are relatively easy to mass-produce, they are said to be cheaper than monolayer carbon nanotubes.

[0033] In addition, commercially available single-layer carbon nanotubes include, for example, the SWeNT series manufactured by Toray Industries, Inc., the MWNT series manufactured by Nikkiso Corporation, and the TUBALL (registered trademark) manufactured by OCSiAl. Commercially available multi-layer carbon nanotubes include, for example, the VGCF (registered trademark) series manufactured by Showa Denko Corporation, Inc., and the Baytubes (registered trademark) manufactured by Bayer Corporation.

[0034] The antistatic layer 6 contains carbon nanotubes as a first antistatic agent (K1), but in addition to the first antistatic agent (K1), it preferably also contains at least one polymer such as a hydroxyl-containing polymer as a binder. By containing at least one polymer such as a hydroxyl-containing polymer as a binder in the antistatic layer 6, the dispersibility of the carbon nanotubes becomes good. Examples of such binders include epoxy resin, phenolic resin, acrylic resin, polyethylene glycol, polyvinyl alcohol, polyvinyl butyral, polyvinyl alcohol-polyvinyl copolymer, polyvinyl acetal, polyvinyl alcohol-polyvinyl acetal copolymer, and polyvinyl alcohol-polyvinyl butyral copolymer. In order to suppress the deterioration of the antistatic layer 6, it is preferable that the antistatic layer 6 does not contain conductive polymers. The binder can be an electrically insulating polymer. If the binder is a polymer that does not have a π-conjugated system, it is less likely to be oxidized and deteriorated, which is therefore preferable.

[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% of the total solid content of the antistatic layer 6. Furthermore, if the content of carbon nanotubes is less than 0.1% by weight, sufficient antistatic properties may not be obtained. Additionally, if the content of carbon nanotubes exceeds 30% by weight, the production cost will increase beyond what is necessary, which is undesirable.

[0036] The thickness of the antistatic layer 6 formed in the antistatic surface protective film 10 according to this embodiment is preferably 0.01 μm to 0.8 μm, more preferably 0.03 μm to 0.5 μm. By making the thickness of the antistatic layer 6 thin, the total light transmittance of the antistatic layer 6 can be easily improved.

[0037] Furthermore, the adhesive layer 2 used in the antistatic surface protective film 10 according to this embodiment is not particularly limited, as long as it adheres to the surface of the object being adhered to, can be easily peeled off after use, and is unlikely to contaminate the object being adhered to. As the adhesive layer 2, considering the durability after lamination with the optical film, an acrylic adhesive layer of cross-linked acrylic polymer is generally used.

[0038] As an adhesive composition constituting the adhesive layer 2, examples include an adhesive composition comprising an acrylic polymer formed by copolymerization of a copolymer having a weight average molecular weight of more than 300,000 and less than 1,000,000, a crosslinking agent (C) a trifunctional or higher isocyanate compound, a crosslinking delay agent (D) and a crosslinking accelerator other than a tin compound, wherein the copolymer is formed by copolymerization of at least 100 parts by weight of at least one (meth)acrylate with an alkyl group having a carbon number of C1 to C18 and at least 1.0 to 6.0 parts by weight of at least one copolymerizable monomer containing a hydroxyl group, without containing a copolymerizable monomer having a carboxyl group.

[0039] Examples of alkyl (meth)acrylates having a carbon number of C1 to C18 as the (A) alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-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 methacrylic acid. Isononyl acrylate, decyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, undecyl acrylate, dodecyl acrylate, tridecyl acrylate, tetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, heptadecanyl acrylate, octadecyl acrylate, myristyl acrylate, isomyristyl acrylate, cetyl acrylate, isocetyl acrylate, stearyl acrylate, isostearyl acrylate, etc. The alkyl group of these alkyl methacrylates can be either acyclic (straight-chain, branched) or cyclic (monocyclic, polycyclic).

[0040] Preferably, the acrylic polymer comprises, in 100 parts by weight of the total amount of (A), at least 50 parts by weight of 2-ethylhexyl acrylate and at least one monofunctional (meth)acrylate alkyl ester monomer with a Tg of 0°C or higher, in a ratio of 5 to 40 parts by weight. In this specification, (meth)acrylate is a general term for acrylates and methacrylates. Furthermore, in 100 parts by weight of the total amount of (A), 2-ethylhexyl acrylate is preferably contained in a ratio of 50 parts by weight or more, more preferably in a ratio of 60 parts by weight or more, and particularly preferably in a ratio of 70 parts by weight or more. Furthermore, in 100 parts by weight of the total amount of (A), at least one monofunctional (meth)acrylate alkyl ester monomer with a Tg of 0°C or higher is preferably contained in a ratio of 5 to 40 parts by weight, more preferably in a ratio of 8 to 40 parts by weight, and particularly preferably in a ratio of 10 to 35 parts by weight. Furthermore, in the following explanation, the term Tg, referring to monomers, simply means the Tg of homopolymers.

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

[0042] Preferably, the acrylic polymer is further copolymerized with (F) a mono(meth)acrylate monomer containing a polyalkylene glycol chain constituting a polyalkylene glycol chain. Further, the mono(meth)acrylate monomer containing a polyalkylene glycol chain constituting (F) can also be added to the adhesive composition as a component different from the acrylic polymer. In either case, the mono(meth)acrylate monomer containing a polyalkylene glycol chain can function as an antistatic agent.

[0043] As the mono(meth)acrylate monomer containing a polyalkyl glycol chain, any compound in which one of the multiple hydroxyl groups of the polyalkyl glycol is esterified into a (meth)acrylate is acceptable. Since the (meth)acrylate group is a polymerizable group, it can copolymerize with the acrylic polymer. It can be a polyalkyl glycol mono(meth)acrylate where other hydroxyl groups remain OH, or an alkoxy polyalkyl glycol mono(meth)acrylate where other hydroxyl groups are converted to alkyl ethers, etc. Furthermore, since polyalkyl glycol mono(meth)acrylate belongs to (F), it will not be classified as (B) even if it contains hydroxyl groups.

[0044] As the polyalkylene glycol constituting the polyalkylene glycol chain, any glycol compound having one or more alkylene groups is acceptable, such as polyethylene glycol, polypropylene glycol, polybutylene glycol, polyethylene glycol-polypropylene glycol, polyethylene glycol-polybutylene glycol, polypropylene glycol-polybutylene glycol, polyethylene glycol-polypropylene glycol-polybutylene glycol, etc.

[0045] Preferably, in the mono(meth)acrylate monomer containing the polyalkylene glycol chain, the average number of repeating epoxides constituting the polyalkylene glycol chain is 3 to 14. Here, "average number of repeating epoxides" refers to the average number of repeating epoxide units in the portion of the "polyalkylene glycol chain" included in the molecular structure of the mono(meth)acrylate monomer containing the polyalkylene glycol chain.

[0046] In addition, the diester component in the mono(meth)acrylate monomer containing polyalkyl glycol chains is preferably 0.2% or less. "Diester component in monomer" refers to the content (by weight %) of polyalkyl glycol di(meth)acrylate contained in the mono(meth)acrylate monomer containing polyalkyl glycol chains.

[0047] The mono(meth)acrylate monomer containing the polyalkyl glycol chain is preferably selected from at least one of the group consisting of polyalkyl glycol mono(meth)acrylate, methoxy polyalkyl glycol (meth)acrylate, and ethoxy polyalkyl glycol (meth)acrylate.

[0048] Relative to 100 parts by weight of the acrylic polymer, the acrylic polymer preferably contains (copolymerizes) at least one of the group consisting of polyalkylene glycol mono(meth)acrylate, methoxy polyalkylene glycol (meth)acrylate, and ethoxy polyalkylene glycol (meth)acrylate as the mono(meth)acrylate monomer containing the polyalkylene glycol chain, more preferably in a ratio of 1 part by weight to 35 parts by weight, and particularly preferably in a ratio of 1 part by weight to 25 parts by weight.

[0049] The preparation method of the acrylic polymer is not particularly limited, and suitable and well-known polymerization methods such as solution polymerization and emulsion polymerization can be used. Preferably, the weight-average molecular weight of the acrylic polymer is greater than 300,000 and less than 1 million.

[0050] Furthermore, the acrylic polymer is an acrylic polymer formed by copolymerization without containing carboxyl-containing copolymerizable monomers. The acid value of the acrylic polymer is preferably 0.1 to 1.0 or less, more preferably 0.0. This improves its stain resistance. Here, "acid value" is one of the indicators of acid content, expressed as the number of mg of potassium hydroxide required to neutralize 1g of a carboxyl-containing polymer.

[0051] The adhesive composition of this embodiment further contains an isocyanate compound with a (C) trifunctional group or higher as a crosslinking agent. Examples of isocyanate compounds with a (C) trifunctional group or higher include, for example, biuret-modified or isocyanurate-modified forms of diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, and xylene ethylene diisocyanate, as well as adducts of polyols with a valence of 3 or higher such as trimethylolpropane and glycerol. As for the proportion of the isocyanate compound with a (C) trifunctional group or higher, for example, it is preferably contained in a proportion of 0.1 parts by weight to 10 parts by weight relative to 100 parts by weight of the acrylic polymer, and more preferably in a proportion of 0.1 parts by weight to 6 parts by weight.

[0052] The adhesive composition according to this embodiment contains a (D) crosslinking delay agent. Examples of the (D) crosslinking delay agent include β-keto esters such as methyl acetate, ethyl acetate, octyl acetate, oleic acid acetate, lauryl acetate, and stearyl acetate, or β-diketones such as acetone, 2,4-hexanedione, and benzoacetone. These are keto-enol tautomer compounds, and by blocking the isocyanate groups of the (C) trifunctional or higher isocyanate compounds, excessive viscosity increase and gelation of the adhesive composition after incorporation of the crosslinking agent can be suppressed, thereby extending the pot-life of the adhesive composition. The (D) crosslinking delay agent is particularly preferably at least one selected from the group consisting of acetone and ethyl acetate. The adhesive composition preferably contains the (D) crosslinking delay agent in a ratio of 0.1 to 300 parts by weight relative to 100 parts by weight of the acrylic polymer.

[0053] The adhesive composition according to this embodiment contains a crosslinking accelerator other than a tin compound as the (E) crosslinking accelerator. The (E) crosslinking accelerator is any substance that functions as a catalyst in the reaction (crosslinking reaction) between the acrylic polymer and the crosslinking agent when a (C) trifunctional or higher isocyanate compound is used as the crosslinking agent. A metal chelating compound is preferably used as the (E) crosslinking accelerator. The metal chelating compound is a compound in which one or more polydentate ligands L are bonded to a central metal atom M. The metal chelating compound may have one or more monodentate ligands X bonded to the metal atom M, or it may not have monodentate ligands X bonded to the metal atom M.

[0054] Specific examples of metal chelating compounds include tri(2,4-pentanedione)iron(III), triacetyl acetone iron, triacetyl acetone titanium, triacetyl acetone ruthenium, diacetyl acetone zinc, triacetyl acetone aluminum, tetraacetyl acetone zirconium, tri(2,4-hexanedione)iron(III), bis(2,4-hexanedione)zinc, tri(2,4-hexanedione)titanium, tri(2,4-hexanedione)aluminum, tetra(2,4-hexanedione)zirconium, etc.

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

[0056] (D) The crosslinking retarder, unlike (E) the crosslinking accelerator, has the effect of inhibiting crosslinking; therefore, it is preferable to appropriately set the ratio of (D) the crosslinking retarder and (E) the crosslinking accelerator. To prolong the shelf life of the adhesive composition and improve its storage stability, the weight ratio of (D) to (E) (D) / (E) is preferably 80 to 1000, more preferably 80 to 700, and particularly preferably 80 to 300. Here, the weight ratio of (D) / (E) refers to the quotient obtained by dividing the weight of (D) by the weight of (E).

[0057] The adhesive composition according to this embodiment may also contain (G) a polyether-modified silicate compound as an optional component. The polyether-modified silicate compound is a silicate compound having a polyether group, which, in addition to having a conventional silicate unit (-SiR12-O-), also has a silicate unit with a polyether group (-SiR1(R2O(R3O)nR4)-O-). Here, R1 represents one or more alkyl or aryl groups, R2 and R3 represent one or more alkylene groups, and R4 represents one or more alkyl or acetyl groups (terminal groups). Examples of polyether groups include polyoxyethylene ((C2H4O)n) or polyoxypropylene ((C3H6O)n) polyoxyalkylene groups. In the silicate unit having a polyether group, the terminal of the polyether group may be an OH group (in the above general formula, R4 = H).

[0058] The polyether-modified silicate compound is preferably a polyether-modified silicate compound with an HLB value of 6 to 12. Furthermore, relative to 100 parts by weight of the acrylic polymer, the adhesive composition preferably contains the polyether-modified silicate compound in a ratio of 0.01 parts by weight to 0.5 parts by weight, more preferably in a ratio of 0.02 parts by weight to 0.35 parts by weight, and particularly preferably in a ratio of 0.02 parts by weight to 0.25 parts by weight. The HLB value refers to the hydrophilic-lipophilic balance value (hydrophilicity to lipophilicity ratio) specified, for example, in JIS K3211 (surfactant terminology).

[0059] The polyether-modified silicate compound can be obtained, for example, by grafting an organic compound having unsaturated bonds and polyoxyalkylene groups onto a polyorganosiloxane backbone having hydrogenated silica groups via a hydrogenation silanization reaction. Specifically, examples of the polyether-modified silicate compound include dimethylsiloxane-methyl(polyoxyethylene)siloxane copolymer, dimethylsiloxane-methyl(polyoxyethylene)siloxane-methyl(polyoxypropylene)siloxane copolymer, and dimethylsiloxane-methyl(polyoxypropylene)siloxane polymer.

[0060] By formulating the polyether-modified silicone compound into the adhesive composition, the adhesion and reprocessing properties of the adhesive layer 2 can be improved. The weight-average molecular weight of the polyether-modified silicone compound is preferably 10,000 or less. Furthermore, from the viewpoint of compatibility with the acrylic polymer, the polyether-modified silicone compound with a low HLB value and low molecular weight exhibits good compatibility. However, if the polyether-modified silicone compound has a low molecular weight, excellent antistatic properties can be obtained even if the HLB value is relatively high and the compatibility with the acrylic polymer is slightly lower.

[0061] The adhesive composition of this embodiment is not limited to the above-mentioned additives, and may also appropriately incorporate known additives such as surfactants, curing accelerators, plasticizers, fillers, curing delay agents, processing aids, anti-aging agents, and antioxidants. They may be used alone or in combination.

[0062] Although the thickness of the adhesive layer 2 used in the antistatic surface protective film 10 according to this embodiment is not particularly limited, it is preferably about 5 μm to 40 μm, and more preferably about 10 μm to 30 μm.

[0063] The adhesive layer 2, which has a micro-adhesion with a peel strength (adhesion) of approximately 0.01 N / 25 mm to 0.3 N / 25 mm to the surface of the adhered object, exhibits excellent operability when peeling the antistatic surface protective film from the adhered object, and is therefore preferred. Furthermore, since the operability when peeling the release film 5 from the antistatic surface protective film 10 is excellent, the peel force required to peel the release film 5 from the adhesive layer 2 is preferably 0.2 N / 50 mm or less.

[0064] In addition, the release film 5 used in the antistatic surface protective film 10 according to this embodiment forms a release agent layer 4 on one side of the resin film 3 by means of a resin composition, wherein the resin composition includes a release agent with dimethyl polysiloxane as the main component, a silicone compound that is liquid at 20°C, and a second antistatic agent (K2).

[0065] Examples of resin films 3 include polyester films, polyamide films, polyethylene films, polypropylene films, and polyimide films. From the viewpoint of excellent transparency and relatively low cost, polyester films are particularly preferred. The resin film 3 can be a non-stretched film or a film stretched uniaxially or biaxially. Furthermore, the stretch ratio of the stretched film and the alignment angle in the axial direction formed during the crystallization of the stretched film can be controlled to specific values. The thickness of the resin film 3 is not particularly limited; for example, a thickness of approximately 12 μm to 100 μm is preferred, and a thickness of approximately 20 μm to 50 μm is easier to handle and therefore more preferred. Additionally, as needed, the surface of the resin film 3 can be subjected to surface modification based on corona discharge, coating with a primer, or other adhesion-enhancing treatments.

[0066] For the release agent constituting the release agent layer 4, which is mainly composed of dimethyl polysiloxane, known silicone release agents of addition reaction type, condensation reaction type, cationic polymerization type, free radical polymerization type, etc. can be cited. As an addition reaction type silicone release agent, commercially available products include, for example, KS-776A, KS-847T, KS-779H, KS-837, KS-778, KS-830 (manufactured by Shin-Etsu Chemical Co., Ltd.), SRX-211, SRX-345, SRX-357, SD7333, SD7220, SD7223, LTC-300B, LTC-350G, LTC-310 (manufactured by Dow Corning Toray Co., Ltd.). Commercially available silicone release agents based on condensation reaction include, for example, SRX-290 and SYLOFF-23 (manufactured by Dow Corning Toray Industries, Inc.). Commercially available silicone release agents based on cationic polymerization include, for example, TPR-6501, TPR-6500, UV9300, VU9315, UV9430 (manufactured by Momentive Performance Materials Inc.), and X62-7622 (manufactured by Shin-Etsu Chemical Industries, Inc.). Commercially available silicone release agents based on free radical polymerization include, for example, X62-7205 (manufactured by Shin-Etsu Chemical Industries, Inc.).

[0067] Examples of silicone compounds that are liquid at 20°C and constitute the release agent layer 4 include polyether-modified silicone, alkyl-modified silicone, and methanol-modified higher fatty acid ester silicone. In this embodiment, to improve the antistatic properties of the adhesive layer 2 surface, it is preferable to use a release agent layer 4 in which the silicone compound, which is liquid at 20°C, is compatible with a release agent whose main component is dimethyl polysiloxane.

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

[0069] The amount of silicone compound added to the release agent layer 4 relative to the release agent varies depending on the type of silicone compound and its compatibility with the release agent. The amount added can be set considering the desired peeling electrostatic voltage when the antistatic surface protective film is peeled from the adhered object, the contamination resistance of the adhered object, and the adhesion characteristics.

[0070] The second antistatic agent (K2) constituting the release agent layer 4 is preferably one that has good dispersibility in the coating liquid forming the release agent layer 4 and does not hinder the curing of the release agent. An alkali metal salt is suitable as the second antistatic agent (K2). Examples of alkali metal salts include those composed of lithium, sodium, and potassium. Specifically, for example, metal salts composed of cations composed of Li+, Na+, and K+, and anions composed of Cl-, Br-, I-, BF4-, PF6-, SCN-, ClO4-, CF3SO3-, (FSO2)2N-, (CF3SO2)2N-, (C2F5SO2)2N-, and (CF3SO2)3C- can be used. In addition, it is particularly preferred that the second antistatic agent (K2) is a Li salt, and is selected from at least one of the compounds group consisting of LiTFSI, LiFSI, and LiTF. Here, LiTFSI represents Li(CF3SO2)2N. Additionally, LiFSI represents Li(FSO2)2N. LiTF represents LiCF3SO3. The alkali metal salt of the second antistatic agent (K2) can be used alone or in combination with two or more. For stabilization of ionic substances, compounds containing polyoxyalkylene structures can also be added to the stripper layer 4.

[0071] The amount of the second antistatic agent (K2) added to the release agent layer 4 relative to the release agent varies depending on the type of the second antistatic agent (K2) and the degree of affinity with the release agent. It can be set by considering the desired peeling electrostatic voltage when the antistatic surface protective film is peeled from the adhered object, the contamination resistance of the adhered object, the adhesion characteristics, etc.

[0072] The preparation method of the coating liquid that forms the release agent layer 4 by mixing the release agent, polyether-modified silicone, and the second antistatic agent (K2) is not particularly limited, and the following methods are possible: (1) adding polyether-modified silicone and the second antistatic agent (K2) to the release agent and mixing them, and then adding and mixing a catalyst for curing the release agent; (2) diluting the release agent with an organic solvent in advance, and then adding and mixing polyether-modified silicone, the second antistatic agent (K2), and the catalyst for curing the release agent; (3) diluting the release agent in an organic solvent in advance, adding and mixing the catalyst, and then adding and mixing polyether-modified silicone and the second antistatic agent (K2). In addition, as needed, a silane coupling agent or other adhesion improver, a material that assists in the antistatic effect of a compound containing polyoxyalkylene compounds, or the like may be added to the coating liquid that forms the release agent layer 4.

[0073] The mixing ratio of the release agent, polyether-modified silicone, and the second antistatic agent (K2) is not particularly limited. Preferably, the weight ratio of polyether-modified silicone and the second antistatic agent (K2) in solid form is approximately 5 to 100 parts by weight relative to 100 parts by weight of the solid component of the release agent. If the amount of polyether-modified silicone and the second antistatic agent (K2) added, calculated as solid component, is less than 5 parts by weight relative to 100 parts by weight of the solid component of the release agent, the amount of the second antistatic agent (K2) transferred onto the surface of the adhesive layer 2 will also be reduced, making it difficult to exert its antistatic function in the adhesive layer 2. Furthermore, it is undesirable for the amount of polyether-modified silicone and the second antistatic agent (K2) added, calculated as solid component, to exceed 100 parts by weight relative to 100 parts by weight of the solid component of the release agent. In this case, the release agent will also be transferred to the surface of the adhesive layer 2 along with the polyether-modified silicone and the second antistatic agent (K2), which may reduce the adhesive properties of the adhesive layer 2.

[0074] The method of forming the adhesive layer 2 on the substrate film 1 of the antistatic surface protective film 10 according to this embodiment and the method of bonding the release film 5 can be performed by known methods and are not particularly limited. The following methods can be used: (1) coating one side of the substrate film 1 with a resin composition for forming the adhesive layer 2 and drying it to form the adhesive layer 2, and then bonding the release film 5; (2) coating the surface of the release film 5 with a resin composition for forming the adhesive layer 2 and drying it to form the adhesive layer 2, and then bonding the substrate film 1.

[0075] Furthermore, the method for forming the adhesive layer 2 and the antistatic layer 6 on the surface of the substrate film 1 can be performed using known methods. 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 method for forming the release agent layer 4 on the resin film 3 can be performed using known methods. Specifically, known coating methods such as gravure coating, Mayer bar coating, and air knife coating can be used.

[0076] The manufacturing method of the antistatic surface protective film 10 of this embodiment may include the following steps (1) to (4). Step (1): The step of preparing the adhesive composition. Step (2): The step of forming an adhesive layer 2 crosslinked with the adhesive composition on one surface of the substrate film 1. Step (3): The step of forming an antistatic layer 6 containing carbon nanotubes as a first antistatic agent (K1) on another surface of the substrate film 1 opposite to the first surface. Step (4): The release film 5 is attached to the surface of the adhesive layer 2 by means of the release agent layer 4, and the second antistatic agent (K2) of the release agent layer 4 is transferred to the surface of the release agent layer 2.

[0077] The antistatic surface protective film 10 is preferably prepared in the order of steps (1) to (4). Step (3) may be performed before step (1), between step (1) and step (2), simultaneously with step (2), or after the release film 5 is attached to the surface of the adhesive layer 2 by the release agent layer 4 in step (4). In addition, if step (3) is performed between step (2) and step (4), the adhesive layer 2 formed on one surface of the substrate film 1 may be exposed, and the adhesive layer 2 formed on one surface of the substrate film 1 may be protected by a release film or the like that without antistatic agent. In addition, as long as the step of preparing the release film 5 is performed before step (4), it can be performed in any order regardless of steps (1) to (3).

[0078] FIG2 is a cross-sectional view showing the state of the antistatic surface protective film 11 after the release film 5 has been peeled off from the antistatic surface protective film 10. By peeling off the release film 5 from the antistatic surface protective film 10 shown in FIG1, a portion of the second antistatic agent (K2) 7 contained in the release agent layer 4 of the release film 5 is transferred (attached) to the surface of the adhesive layer 2 of the antistatic surface protective film 11. Therefore, in FIG2, the second antistatic agent (K2) transferred to the surface of the adhesive layer 2 of the antistatic surface protective film 11 is schematically shown by the dot symbol 7. In addition, an antistatic layer 6 containing carbon nanotubes as the first antistatic agent (K1) is formed on the other surface of the substrate film 1 opposite to the surface on which the 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 shown in FIG. 2 with the release film peeled off, is applied to the substrate, the second antistatic agent (K2) 7 transferred to the surface of the adhesive layer 2 comes into contact with the surface of the substrate. In this way, when the antistatic surface protective film 11 is peeled off from the substrate again, the peeling electrostatic voltage can be suppressed to a low level. Furthermore, in addition to the second antistatic agent (K2) 7, a silicone compound that is liquid at 20°C can also be transferred from the release agent layer 4 to the surface of the adhesive layer 2.

[0079] FIG3 is a cross-sectional view showing an embodiment of the optical component of this embodiment. The antistatic surface protective film 11, with the release film 5 peeled off from the antistatic surface protective film 10 according to this embodiment, exposing the adhesive layer 2, is adhered to the optical component 8, which is the adhered object, by means of the adhesive layer 2. Furthermore, an antistatic layer 6 containing carbon nanotubes as a first antistatic agent (K1) is formed on the other surface of the substrate film 1 opposite to the surface on which the adhesive layer 2 is formed. That is, FIG3 shows the optical component 20 with the antistatic surface protective film 11 of this embodiment adhered to it. Examples of optical components 8 include polarizing plates, retardation plates, lens films, polarizing plates that combine retardation plates and lens films. Such optical components 8 can be used as constituent components of liquid crystal display devices such as liquid crystal display panels, and various optical system devices such as measuring instruments. In addition, optical components 8 can include anti-reflective films, hard coatings, transparent conductive films for touch panels, and other optical films.

[0080] The antistatic surface protective films 10 and 11 of this embodiment can be appropriately used to adhere to surfaces of optical films such as low-reflection polarizing plates (LR polarizing plates) and anti-glare low-reflection polarizing plates (AG-LR polarizing plates) that have undergone anti-fouling treatment using silicone compounds, fluorine compounds, etc. According to the optical component 20 of this embodiment, when the antistatic surface protective films 10 and 11 are peeled off from the optical component (optical film) that is the adhered object, the peeling electrostatic voltage can be suppressed to a sufficiently low level. Therefore, there is no risk of damaging circuit components such as driver ICs, TFT elements, and gate drive circuits, which can improve the production efficiency in the manufacturing process of liquid crystal display panels and ensure the reliability of the manufacturing process.

[0081] The antistatic surface protective films 10 and 11 of this embodiment are suitable as surface protective films for polarizing plates. The adhesive layer 2 of the antistatic surface protective film 10 can also be adhered to the protective layer of the polarizer of the polarizing plate. Furthermore, in the application of the surface protective film for polarizing plates, the protective layer of the polarizer of the polarizing plate, which is the adhered object, can be at least one selected from the group consisting of TAC films, PMMA films, and PET films. Here, TAC is an abbreviation for cellulose triacetate, PMMA is an abbreviation for polymethyl methacrylate, and PET is an abbreviation for polyethylene terephthalate. In addition, in the application of the surface protective film for polarizing plates, the surface treatment performed on the surface of the protective layer of the polarizer of the polarizing plate, which is the adhered object, can be at least one selected from the group consisting of untreated, AG treated, LR treated, AR treated, AG-LR treated, and AG-AR treated. Here, AG refers to anti-glare, LR refers to low reflection, and AR refers to anti-reflection.

[0082] In the antistatic surface protective films 10 and 11 of this embodiment, the surface resistivity of the adhesive layer 2 transferred from the second antistatic agent (K2) of the release agent layer 4 is preferably 1.0 × 10 + 12 Ω / □ or less, more preferably 5.0 × 10 + 11 Ω / □ or less, and particularly preferably 1.0 × 10 + 11 Ω / □ or less. If the surface resistivity of the adhesive layer 2 is high, the performance of releasing static electricity generated when the adhesive layer 2 is peeled off from the adhered object is poor. Therefore, by making the surface resistivity of the adhesive layer 2 sufficiently low, the peeling static voltage generated along with the static electricity generated when the adhesive layer 2 is peeled off from the adhered object can be reduced, and the impact on the adhered object can be suppressed.

[0083] Furthermore, in the antistatic surface protective films 10 and 11 of this embodiment, an antistatic layer 6 containing carbon nanotubes as a first antistatic agent (K1) is formed on the other surface of the substrate film 1, which is opposite to the surface on which the adhesive layer 2 is formed. The initial surface resistivity of this antistatic layer 6 is preferably 1.0 × 10 + 10 Ω / □ or less, and even after being exposed to the atmosphere at 23°C × 50%RH for 90 days, it still maintains a value of 1.0 × 10 + 10 Ω / □ or less. Conventional antistatic layers show a trend of gradually decreasing surface resistivity when exposed to the atmosphere over time. Therefore, after storing the antistatic surface protective films 10 and 11 of this embodiment in an atmosphere exposed to 23°C × 50%RH for 90 days, the surface resistivity of the antistatic layer 6 is measured at least once, and it is preferably 1.0 × 10 + 10 Ω / □ or less.

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

[0085] When measuring the stripping electrostatic voltage of the low-refractive-index layer, PMMA substrates and TAC substrates can be used as substrates for forming the low-refractive-index layer on the surface. Furthermore, in the antistatic surface protective films 10 and 11 of this embodiment, the stripping electrostatic voltage of the adhesive layer 2, which is transferred from the second antistatic agent (K2) of the stripping agent layer 4, for the plain layer on the surface of the PMMA substrate and the TAC substrate without any treatment, is preferably in the range of +0.3kV to -0.3kV.

[0086] Preferably, after the adhesive layer 2 is adhered to the substrate such as the polarizing plate, it is placed in an environment with a temperature of 60°C and a humidity of 90%RH for 2 days (48 hours). After being removed from the environment, it is peeled off after 1 day without contamination. Furthermore, as the substrate, a polarizing plate with a protective layer laminated on the polarizing mirror and a low-reflection surface treatment performed on the surface of the protective layer using a composition containing a fluorine compound can be an example. The fluorine-containing composition used for the low-reflection surface treatment can be the same as or different from the resin composition used to form the low-refractive-index layer containing a fluorine compound. As the protective layer and surface treatment, the protective layer of the polarizing mirror and the surface treatment performed on its surface can be examples. Specifically, a polarizing plate whose surface substrate is selected from the group consisting of TAC films, PMMA films, and PET films, and whose surface treatment performed on the surface substrate is selected from the group consisting of untreated, AG treated, LR treated, AR treated, AG-LR treated, and AG-AR treated.

[0087] In the antistatic surface protective films 10 and 11 of this embodiment, the adhesion of the adhesive layer 2 to the adhered object can be evaluated by the following method: After the adhesive layer 2, which is cross-linked with the adhesive composition, is laminated to one side of a polyester film with a thickness of 38 μm with a thickness of 15 μm, the antistatic surface protective film 11, formed by transferring the second antistatic agent (K2) from the release agent layer 4 onto the surface of the adhesive layer 2, is adhered to the surface of a polarizing plate, which is an example of an adhered object. Then, when the antistatic surface protective film 11 is peeled off from the polarizing plate, preferably, the adhesion is 0.01 N / 25 mm to 0.1 N / 25 mm at a low peeling speed of 0.3 m / min, and the adhesion is 1.0 N / 25 mm or less at a high peeling speed of 30 m / min, and more preferably, the adhesion is 0.2 N / 25 mm to 0.8 N / 25 mm at a high peeling speed of 30 m / min. This results in minimal change in adhesive strength due to peeling speed, allowing for rapid peeling of the antistatic surface protective film 11 even at high speeds. Furthermore, even when temporarily removing the antistatic surface protective film 11 for re-adhesion, it can be easily peeled off from the adhered object without requiring excessive force.

[0088] In the antistatic surface protective films 10 and 11 of this embodiment, after the adhesive composition is crosslinked, the gel fraction of the adhesive layer 2 transferred by the second antistatic agent (K2) from the release agent layer 4 is preferably 95% to 100%, more preferably 97% to 100%. Thus, due to the high gel fraction of the adhesive layer 2, the adhesion at low peeling speeds does not become excessive, and the leaching of unpolymerized monomers or oligomers from the adhesive layer 2 is reduced, thereby improving reworkability or durability under high temperature and humidity conditions, and suppressing contamination of the adhered material.

[0089] The adhesive film of this embodiment has an adhesive layer formed on one or both sides of the resin film by crosslinking the adhesive composition of this embodiment. Furthermore, the surface protective film of this embodiment is a surface protective film on one side of the resin film by forming an adhesive layer formed on one side of the resin film by crosslinking the adhesive composition of this embodiment. The surface protective film of this embodiment becomes an antistatic surface protective film 10, 11 by transferring a second antistatic agent (K2) from the release agent layer 4 onto the surface of the adhesive layer 2, and possesses excellent antistatic properties. Furthermore, regarding the antistatic surface protective films 10, 11 of this embodiment, the balance of adhesive force is excellent at both low and high peel speeds, further exhibiting anti-fouling properties. Therefore, it is suitable for use as a surface protective film for polarizing plates.

[0090] Furthermore, by depositing an adhesive layer 2, which has been cross-linked with the adhesive composition and then transferred with a second antistatic agent (K2) from the release agent layer 4, onto at least one side of the optical film, an optical film with an adhesive layer can be obtained. Examples of optical films include polarizing films, retardation films, anti-reflective films, anti-glare films, ultraviolet absorption films, infrared absorption films, optical compensation films, and brightness enhancement films. Examples of devices suitable for optical components 8 and 20 include liquid crystal panels, organic EL panels, and touch panels. In the case of optical surface protective films such as surface protective films for polarizing plates and adhesive films, it is preferable that the substrate film 1 and the adhesive layer 2 have sufficient transparency. [Example]

[0091] Hereinafter, the present invention will be specifically described by way of examples.

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

[0093] [Comparative Example 3] As an antistatic agent composed of conductive polymers, a mixture of polyaniline (manufactured by Nippon Catalyst Co., Ltd.) and polythiophene (manufactured by Teikoku Pharmaceutical Co., Ltd.) with a solid component weight ratio of 10:90 was dissolved in a solvent to obtain a coating solution that forms the antistatic layer of Comparative Example 3.

[0094] <Preparation of Adhesive Composition> [Example 1] Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube to replace the air in the reaction apparatus. 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), and 10 parts by weight of polypropylene glycol monoacrylate (n=12) were added to the reaction apparatus along with a solvent (ethyl acetate). Then, 0.1 parts by weight of azobisisobutyronitrile (AIBN) as a polymerization initiator was added dropwise over 2 hours, and the reaction was carried out at 65°C for 6 hours to obtain the acrylic polymer solution of Example 1. After adding 8.5 parts by weight of acetone (AA) to the acrylic polymer solution and stirring, 2.0 parts by weight of Coronate HX (isocyanurate of hexamethylene diisocyanate compound), 0.1 parts by weight of triacetone titanium, and 0.05 parts by weight of polyether-modified silica compound (HLB=7) were added and stirred to obtain the adhesive composition of Example 1.

[0095] [Examples 2-4 and Comparative Examples 1-4] Except that the composition of the adhesive composition of Example 1 was adjusted to that shown in Table 1, the adhesive compositions of Examples 2-4 and Comparative Examples 1-4 were obtained in the same manner as in Example 1. In the case of the adhesive compositions of Comparative Examples 1 and 2, the compounds shown in "Antistatic Agent (Adhesive Layer)" in Table 2 were further added to the adhesive compositions. In addition, the acrylic polymers of Examples 1-4 and Comparative Examples 1-3 were copolymers with a weight average molecular weight of more than 300,000 and less than 1,000,000. The acrylic polymer of Comparative Example 4 was a copolymer with a weight average molecular weight of 100,000.

[0096] In each column of Table 1 and in "Antistatic Agent (Adhesive Layer)" of Table 2, the total amount of (A) alkyl methacrylates with C1 to C18 carbon atoms is set to 100 parts by weight to calculate the weight parts of each component. "(D) / (E)" in Table 2 is the weight ratio. In addition, in each column of Table 1 (B) to (G), when the weight parts of the acrylic polymer calculated as the total amount of (A), (B), and (F) are set to 100 parts by weight, the value in parentheses () indicates the content ratio (parts by weight) of each component at this time. In addition, in "Antistatic Agent (Adhesive Layer)" of Table 2, LiTFSI represents Li(CF3SO2)2N, and LiTF represents LiCF3SO3.

[0097] [Table 1]

[0098] [Table 2]

[0099] In addition, the compound names of the abbreviation symbols of each component (A) to (G) used in Table 1 are shown in Table 3. Furthermore, CORONATE (registered trademark) HX, CORONATE HL, and CORONATE L are trade names of TOSOH CORPORATION, and TAKENATE (registered trademark) D-140N and D-110N are trade names of Mitsui Chemicals, Inc. Furthermore, in (F) the mono(meth)acrylate monomers containing polyalkylene glycol chains constituting the polyalkylene glycol chain, F-1 to F-3 are monomers with a diester component of 0.2 wt% or less, and F-4 is a monomer with a diester component of 0.8 wt%. The n value represents the average number of repetitions of the epoxide. Furthermore, in (G) the polyether-modified silicate compounds, the weight-average molecular weight of G-1 to G-6 is 10,000 or less.

[0100] [Table 3]

[0101] <Preparation of Antistatic Surface Protective Film> [Example 1] 5 parts by weight of addition-reaction type silicone (manufactured by Dow Corning Toray Industries, Inc., product name: SRX-345), 0.15 parts by weight of polyether-modified silicone (manufactured by Dow Corning Toray Industries, Inc., product name: SH8400), 0.5 parts by weight of lithium bis(trifluoromethylsulfonyl)imine (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 platinum catalyst (manufactured by Dow Corning Toray Industries, Inc., product name: SRX-212CATALYST) were mixed and stirred to prepare the coating solution for forming the release agent layer of Example 1. On the surface of a 38 μm thick polyethylene terephthalate (PET) film, to achieve a dried thickness of 0.2 μm, the coating liquid for forming the release agent layer of Example 1 was applied using a Meller rod, and dried in a hot air circulating oven at 120°C for 1 minute to obtain the release film of Example 1. To achieve a dried thickness of 15 μm, the adhesive composition of Example 1 was applied to the surface of the 38 μm thick PET film, which served as the substrate film, and then dried in a hot air circulating oven at 100°C for 2 minutes to form an adhesive layer. Further, to achieve a dried thickness of 0.05 μm, the coating liquid for forming an antistatic layer of Example 1 was applied to the surface of the substrate film opposite to the surface where the adhesive layer was formed, and then dried in a hot air circulating oven at 100°C for 2 minutes to form an antistatic layer. Then, the release agent layer (silicone-treated surface) of the release film of Example 1 prepared as described above was bonded to the surface of this adhesive layer. The obtained adhesive film was kept at 40°C for 5 days to cure the adhesive, thereby obtaining the antistatic surface protective film of Example 1.

[0102] [Examples 2-4] Except that the composition of the coating liquid forming the release agent layer in Example 1 was adjusted to that described in Table 4, the coating liquids forming the release agent layer in Examples 2-4 were manufactured in the same manner as in Example 1, and the release films of Examples 2-4 were obtained. In addition, except that the adhesive composition in Example 1 was set to the adhesive composition in Examples 2-4, the thickness of the antistatic layer after drying was adjusted to that described in Table 5, and the release film in Example 1 was adjusted to the release film in Examples 2-4, the antistatic surface protective films of Examples 2-4 were obtained in the same manner as in Example 1.

[0103] [Comparative Example 1] 5 parts by weight of addition-reaction silicone (manufactured by Dow Corning 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 (manufactured by Dow Corning Toray Industries, Inc., product name: SRX-212CATALYST) were mixed and stirred to prepare the 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 with a thickness of 38 μm using a Meller rod to achieve a dry thickness of 0.2 μm, and then dried in a hot air circulating oven at 120°C for 1 minute to obtain the release film of Comparative Example 1. To achieve a dried thickness of 15 μm, the adhesive composition of Comparative Example 1 was applied to the surface of a 38 μm thick polyethylene terephthalate film, which served as the substrate film. The film was then dried in a hot air circulating oven at 100°C for 2 minutes to form an adhesive layer. Furthermore, no antistatic layer was formed on the opposite surface of the substrate film to the surface where the adhesive layer was formed. Then, the release agent layer (silicone-treated surface) of the release film of Comparative Example 1, prepared as described above, was adhered to the surface of this adhesive layer. The obtained adhesive film was kept at 40°C for 5 days to cure the adhesive, thereby obtaining the antistatic surface protective film of Comparative Example 1.

[0104] [Comparative Example 2] Except that the adhesive composition of Comparative Example 1 was used as the adhesive composition of Comparative Example 2, the antistatic surface protective film of Comparative Example 2 was obtained in the same manner as Comparative Example 1. [Comparative Examples 3-4] Except that the composition of the coating liquid forming the release agent layer in Example 1 was adjusted to that shown in Table 4, the coating liquid forming the release agent layer of Comparative Examples 3-4 was manufactured in the same manner as Example 1, and the release film of Comparative Examples 3-4 was obtained. Furthermore, except that the adhesive composition of Example 1, the coating liquid forming the antistatic layer, and the release film were adjusted to the adhesive composition, the coating liquid forming the antistatic layer, and the release film of Comparative Examples 3-4, respectively, the antistatic surface protective film of Comparative Examples 3-4 was obtained in the same manner as Example 1.

[0105] In addition, in Table 4, “Second Antistatic Agent (K2)”, LiTFSI represents Li(CF3SO2)2N, LiFSI represents Li(FSO2)2N, and LiTF represents LiCF3SO3. In addition, in Table 5, “First Antistatic Agent (K1)”, CNT represents multilayer carbon nanotubes, PANI represents polyaniline, and PEDOT is a type of polythiophene, representing poly(3,4-ethylenedioxythiophene).

[0106] [Table 4]

[0107] [Table 5]

[0108] <Test Methods and Evaluation> The antistatic surface protective films of Examples 1-4 and Comparative Examples 1-4 were cured for 7 days at a temperature of 23°C and a humidity of 50%RH, and then evaluated using the following test methods. Furthermore, in the antistatic surface protective films of Examples 1-4 and Comparative Examples 3-4, by peeling off the release film, the second antistatic agent (K2) could be transferred from the release agent layer to the surface of the adhesive layer. In the antistatic surface protective films of Comparative Examples 1-2, the adhesive layer contained all the compounds shown in Table 2, "Antistatic Agent (Adhesive Layer)".

[0109] <Test Method for Adhesion> The release film is peeled off, and an antistatic surface protective film with a 15 μm thick adhesive layer is adhered to the surface of the polarizing plate via the adhesive layer. After being left for 1 day, it undergoes a pressure-heat treatment at 50°C and 5 atmospheres for 20 minutes. After being left at room temperature for 12 hours, this is used as the sample for adhesion testing. The obtained sample is peeled off along 180° at a low speed (0.3 m / min) or a high speed (30 m / min) using a tensile testing machine, and the measured peel strength is taken as the adhesion. Here, the protective layer of the polarizer of the polarizing plate is polymethyl methacrylate (PMMA) with an AG-LR treatment layer.

[0110] <Test Method for Surface Resistivity> After curing the antistatic surface protective film and before attaching it to the polarizing plate, the release film is peeled off to expose the adhesive layer. The surface resistivity of the adhesive layer is measured using a Hiresta (registered trademark) UP-HT450 resistivity meter (manufactured by Mitsubishi Chemical Analytech, Co., Ltd.). Similarly, the initial surface resistivity of the antistatic layer is measured. Furthermore, the surface resistivity of the antistatic layer is measured after 90 days of storage in an environment of 23°C × 50%RH exposed to the atmosphere.

[0111] <Test Method for Peeling Electrostatic Voltage> The release film is peeled off, and the antistatic surface protective film exposing the adhesive layer is adhered to a polarizing plate having a low-refractive-index layer on the adhered surface. This low-refractive-index layer is formed using a low-refractive-index layer forming composition containing a fluorine compound. Using high-precision electrostatic sensors SK-035 and SK-200 (manufactured by Keyence Corporation), the voltage generated when the adhered object becomes charged during a 180° peel at a tensile speed of 30 m / min is measured (electrostatic voltage). The maximum measured value is taken as the peeling electrostatic voltage.

[0112] <Test Method for Stain Resistance> Using a laminating machine, a polarizing plate having the surface substrate and surface treatment (untreated for plain surfaces) shown in Table 7 is bonded to one side of a glass plate via an adhesive layer (double-sided adhesive tape). Then, using the laminating machine, an antistatic surface protective film, exposing the adhesive layer after peeling off the release liner, is bonded to the surface of the polarizing plate. After bonding to the substrate, the plate is placed in an environment with a temperature of 60°C and a humidity of 90%RH for 2 days (48 hours). After being removed from the environment and after 1 day, the antistatic surface protective film is peeled off, and the surface contamination status of the polarizing plate is visually observed. Regarding the criteria for judging stain resistance, a surface without contamination is evaluated as "○", a slightly contaminated surface as "△", and a contaminated surface as "×".

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

[0114] [Table 6]

[0115] [Table 7]

[0116] Regarding the antistatic surface protective films of Examples 1-4, the initial surface resistivity of the antistatic layer formed on the surface of the substrate film is 1.0 × 10 + 10 Ω / □ or less. Even after the antistatic layer is exposed to the atmosphere at 23°C and 50% RH for 90 days, it still maintains a value of 1.0 × 10 + 10 Ω / □ or less. In addition, the antistatic surface protective films of Examples 1-4 have an adhesion to the polarizing plate as the adherend at a low peel speed of 0.3 m / min and an adhesion at a high peel speed of 30 m / min of 0.0 N / 25 mm or less. Therefore, the adhesion performance is excellent due to the balance of adhesion at both low and high peel speeds. Furthermore, regarding the antistatic surface protective films of Examples 1-4, since the antistatic agent of the release agent layer is transferred to the surface of the adhesive layer, the surface resistivity of the adhesive layer is 1.0 × 10 + 12 Ω / □ or less. The peeling electrostatic voltage of the adhesive layer for low-refractive-index layers formed using a composition containing fluorine compounds is in the range of +0.3 kV to -0.3 kV, exhibiting excellent antistatic performance. Furthermore, after the antistatic surface protective films of Examples 1-4 were adhered to the substrates and placed in an environment with a temperature of 60°C and a humidity of 90% RH for 48 hours, and then removed from the environment and left for one day, no contamination was observed in the various polarizing plates used as the substrates, demonstrating excellent contamination resistance. In other words, based on the evaluation results shown in Tables 6-7, it is confirmed that the antistatic surface protective films of Examples 1-4 can solve the technical problems of the present invention.

[0117] Regarding the antistatic surface protective films of Comparative Examples 1 and 2, no antistatic layer containing an antistatic agent was formed on the other surface of the substrate film, and the surface resistivity of the other surface of the substrate film was extremely high. In addition, the antistatic surface protective film of Comparative Example 1 (the Tg of n-butyl acrylate (BA), a monofunctional (meth)acrylate alkyl ester monomer copolymerized in an acrylic polymer, was less than 0°C, the adhesive layer contained an antistatic agent throughout, and the release agent layer did not contain silicone compounds and antistatic agents that are liquid at 20°C) had slightly poorer stain resistance. Furthermore, in the antistatic surface protective film of Comparative Example 2 (which copolymerized too many monofunctional (meth)acrylate alkyl monomers and hydroxyl-containing monomers in an acrylic polymer, the acrylic polymer did not contain mono(meth)acrylate monomers containing polyalkyl glycol chains constituting the polyalkyl glycol chain, the adhesive layer contained an antistatic agent throughout, and the release agent layer did not contain silicone compounds and antistatic agents that are liquid at 20°C), the adhesion was strong, the peeling electrostatic voltage was high, and the contamination resistance was poor. In addition, regarding the antistatic surface protective film of Comparative Example 3, an antistatic layer containing a conductive polymer as an antistatic agent was 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 was less than 1.0 × 10 + 10 Ω / □, but after 90 days of exposure to the atmosphere at 23°C and 50% RH, the surface resistivity of the antistatic layer exceeded 1.0 × 10 + 10 Ω / □. Furthermore, in the antistatic surface protective film of Comparative Example 3 (the acrylic polymer does not contain alkyl (meth)acrylate monomers with a Tg of 0°C or higher, nor mono(meth)acrylate monomers containing polyalkyl glycol chains constituting the polyalkyl glycol chain, but contains carboxyl-containing monomers), the adhesion is strong, the surface resistivity of the adhesive layer is high, the peeling electrostatic voltage is high, and the stain resistance is poor. In addition, in the antistatic surface protective film of Comparative Example 4 (the acrylic polymer has a low weight-average molecular weight), the stain resistance is poor. As described above, the antistatic surface protective films of Comparative Examples 1-4 failed to solve the technical problems of the present invention. [Simplified Explanation of the Diagram]

[0027] Figure 1 is a cross-sectional view showing the concept of the antistatic surface protective film of the present invention. Figure 2 is a cross-sectional view showing the state of the release film peeled off from the antistatic surface protective film of the present invention. Figure 3 is a cross-sectional view showing an embodiment of the optical component of the present invention.

Claims

1. A method for manufacturing an antistatic surface protective film, characterized in that the method for manufacturing the antistatic surface protective film is carried out in the order of steps (1) to (4): Step (1): a step of preparing an adhesive composition, wherein the adhesive composition contains an acrylic polymer and a crosslinking agent, wherein the acrylic polymer is an acrylic polymer formed by copolymerization of a copolymer having a weight average molecular weight of more than 300,000 and less than 1 million, wherein, The aforementioned copolymer is prepared by copolymerizing at least 100 parts by weight of (A) alkyl methacrylates with a carbon number of C1 to C18 and at least 1.0 to 6.0 parts by weight of (B) a copolymerizable monomer containing a hydroxyl group, in a manner that does not contain a copolymerizable monomer with a carboxyl group. The aforementioned adhesive composition contains (C) a trifunctional or higher isocyanate compound as the aforementioned crosslinking agent, and further contains (D) a crosslinking delay agent and (E) a crosslinking accelerator other than a tin compound as the crosslinking accelerator; Step (2): the step of forming an adhesive layer crosslinked with the aforementioned adhesive composition on one surface of a substrate film formed of a transparent resin; Step (3): forming an antistatic layer containing only carbon nanotubes and hydroxyl-containing polymers as a first antistatic agent (K1) on the other surface of the substrate film opposite to the aforementioned surface; and step (4): attaching a release film containing a second antistatic agent (K2) to the surface of the aforementioned adhesive layer via the release agent layer, and transferring the aforementioned second antistatic agent (K2) of the release agent layer to the surface of the aforementioned adhesive layer, wherein the release agent layer is formed by a resin composition comprising a release agent with dimethyl polysiloxane as the main component, a silicone compound that is liquid at 20°C, and the aforementioned second antistatic agent (K2).

2. The method for manufacturing the antistatic surface protective film as described in claim 1, wherein, An antistatic surface protective film is formed by laminating an adhesive layer of the aforementioned crosslinked adhesive composition to one side of a polyester film with a thickness of 15 μm and transferring the aforementioned second antistatic agent (K2) to the surface of the aforementioned adhesive layer. After the antistatic surface protective film is attached to the surface of a polarizing plate, when the aforementioned antistatic surface protective film is peeled off from the aforementioned polarizing plate, the adhesion is 0.01 N / 25 mm to 0.1 N / 25 mm at a low peeling speed of 0.3 m / min, and the adhesion is less than 1.0 N / 25 mm at a high peeling speed of 30 m / min.

3. A method for manufacturing an antistatic surface protective film as described in claim 1 or 2, wherein, The initial surface resistivity of the aforementioned antistatic layer on the surface of the aforementioned substrate film is less than 1.0×10+10Ω / □, and the surface resistivity of the antistatic layer after being stored for 90 days in an environment exposed to the atmosphere at 23°C and 50%RH is less than 1.0×10+10Ω / □.

4. A method for manufacturing an antistatic surface protective film as described in claim 1 or 2, wherein, The aforementioned adhesive composition or at least one of the aforementioned acrylic polymers comprises (F) a mono(meth)acrylate monomer containing a polyalkylene glycol chain constituting a polyalkylene glycol chain.

5. A method for manufacturing an antistatic surface protective film as described in claim 1 or 2, wherein, The aforementioned second antistatic agent (K2) is an alkali metal salt.

6. An antistatic surface protective film, said antistatic surface protective film being formed by forming an adhesive layer on a surface of a substrate film formed of a transparent resin, said adhesive layer being formed by crosslinking an adhesive composition containing an acrylic polymer and a crosslinking agent, characterized in that said acrylic polymer is an acrylic polymer formed by copolymerizing an acrylic polymer having a weight average molecular weight of more than 300,000 and less than 1,000,000, wherein, The aforementioned copolymer is prepared by copolymerizing at least 100 parts by weight of (A) alkyl methacrylates with a carbon number of C1 to C18 and at least 1.0 to 6.0 parts by weight of (B) a copolymerizable monomer containing hydroxyl groups, without containing a copolymerizable monomer with a carboxyl group. The aforementioned adhesive composition contains (C) a trifunctional or higher isocyanate compound as the aforementioned crosslinking agent, and further contains (D) a crosslinking delay agent and (E) a crosslinking accelerator other than a tin compound as the crosslinking accelerator. An antistatic layer containing only carbon nanotubes and a hydroxyl-containing polymer as a first antistatic agent (K1) is formed on the other surface of the aforementioned substrate film opposite to the aforementioned surface. A release film containing a second antistatic agent (K2) is attached to the surface of the aforementioned adhesive layer via the release agent layer, and the aforementioned second antistatic agent (K2) of the release agent layer is transferred to the surface of the aforementioned adhesive layer. The aforementioned release agent layer is formed by a resin composition comprising a release agent with dimethyl polysiloxane as the main component, a silicone compound that is liquid at 20°C, and the aforementioned second antistatic agent (K2).

7. The antistatic surface protective film as described in claim 6, wherein, The aforementioned adhesive composition or at least one of the aforementioned acrylic polymers comprises (F) a mono(meth)acrylate monomer containing a polyalkylene glycol chain constituting a polyalkylene glycol chain.

8. The antistatic surface protective film as described in claim 6 or 7, wherein, The aforementioned second antistatic agent (K2) is an alkali metal salt.

9. The antistatic surface protective film as claimed in claim 6 or 7, wherein, The aforementioned antistatic surface protective film is used as a surface protective film for a polarizing plate. The protective layer of the polarizing lens of the aforementioned polarizing plate is selected from the group consisting of TAC film, PMMA film, and PET film. The surface treatment performed on the surface of the protective layer of the polarizing lens of the aforementioned polarizing plate is selected from the group consisting of untreated, AG treated, LR treated, AR treated, AG-LR treated, and AG-AR treated.

10. The antistatic surface protective film as claimed in claim 6 or 7, wherein, The aforementioned (B) copolymerizable monomer containing hydroxyl groups is selected from at least one of the following groups of compounds: 8-hydroxyoctyl methacrylate, 6-hydroxyhexyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxyethyl methacrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and N-hydroxyethyl(meth)acrylamide.

11. The antistatic surface protective film as claimed in claim 6 or 7, wherein, The aforementioned (D) crosslinking retarder is a ketone-enol tautomer compound, and contains the aforementioned (D) crosslinking retarder in a ratio of 0.1 parts by weight to 300 parts by weight relative to 100 parts by weight of the aforementioned acrylic polymer. The aforementioned (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 contains the aforementioned (E) crosslinking accelerator in a ratio of 0.001 parts by weight to 0.5 parts by weight relative to 100 parts by weight of the aforementioned acrylic polymer. The weight ratio of the aforementioned (D) to the aforementioned (E) is 80 to 1000.

12. The antistatic surface protective film as described in claim 6 or 7, wherein, Relative to 100 parts by weight of the aforementioned acrylic polymer, the aforementioned adhesive composition contains, in a ratio of 0.01 to 0.5 parts by weight, a polyether-modified silicate compound with an HLB value of 6 to 12 and a weight-average molecular weight of less than 10,000.

13. The antistatic surface protective film as claimed in claim 7, wherein, The average repeat number of the epoxy alkyl group constituting the polyalkyl glycol chain in the aforementioned mono(meth)acrylate monomer containing polyalkyl glycol chain is 3 to 14, the diester component in the aforementioned mono(meth)acrylate monomer containing polyalkyl glycol chain is 0.2% or less, and in 100 parts by weight of the aforementioned acrylic polymer, at least one of the group consisting of polyalkyl glycol mono(meth)acrylate, methoxy polyalkyl glycol (meth)acrylate, and ethoxy polyalkyl glycol (meth)acrylate is contained as the aforementioned mono(meth)acrylate monomer containing polyalkyl glycol chain in a proportion of 1 to 50 parts by weight.

14. The antistatic surface protective film as claimed in claim 6 or 7, wherein, The aforementioned silicone compounds are polyether-modified silicones.

15. The antistatic surface protective film as claimed in claim 6 or 7, wherein, The aforementioned second antistatic agent (K2) is a Li salt, and is at least one selected from the group of compounds consisting of LiTFSI, LiFSI, and LiTF.

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