TWI671188B - Antistatic surface-protective film - Google Patents

Abstract

The invention provides an antistatic surface protection film, which has less pollution to an adherend, does not deteriorate over time, and has excellent peeling antistatic performance. The anti-static surface protective film (10) is characterized in that an antistatic agent-free adhesive layer (2) and an antistatic agent are sequentially laminated on one surface of a base film (1) formed of a transparent resin. An electrostatic agent layer (3) and a peeling film (4).

Description

Anti-static surface protection film

The present invention relates to an antistatic surface protection film adhered to the surface of an optical element (hereinafter, also sometimes referred to as an optical film) such as a polarizing plate, a retardation plate, and a lens film for a display. In more detail, the present invention provides an antistatic surface protection film, which has less contamination to an adherend, does not deteriorate over time, and has excellent peeling antistatic performance.

When manufacturing and transporting optical films such as polarizing plates, retardation plates, display lens films, anti-reflection films, hard coating films, and transparent conductive films for touch panels, and optical products such as displays using these, The surface of the film is adhered to a surface protection film to prevent surface contamination and damage in subsequent steps. In order to save the time of peeling off the surface protective film and then bonding, and improve the working efficiency, the appearance inspection of the optical film as a product may be performed in a state where the surface protective film is bonded to the optical film.

For a long time, in the manufacturing steps of optical products, in order to prevent damage or adhesion of contaminants, a surface protection film having an adhesive layer on one surface of a base film is generally used. The surface protection film is bonded to the optical film through an adhesive layer having a weak adhesive force. The reason why the adhesive layer has a weak adhesive force is that when the used surface protective film is peeled off from the surface of the optical film, the adhesive layer can be easily peeled off and the adhesiveness can be improved. The adhesive does not adhere to and remain on the optical film product as an adherend (so-called prevention of generation of adhesive residue).

In recent years, in the production steps of liquid crystal display panels, although the following phenomena occur in small numbers, there are still the following phenomena: The peeling static voltage generated when the surface protective film attached to the optical film is peeled off and removed is used for Circuit elements such as a driver IC that controls a display screen of the liquid crystal display panel are damaged, and alignment of liquid crystal molecules is damaged.

In addition, in order to reduce the power consumption of the liquid crystal display panel, the driving voltage of the liquid crystal material is reduced, and the destruction voltage of the driving IC is also reduced accordingly. Recently, it has been required to make the peeling static voltage within a range of +0.7 kV to -0.7 kV.

Therefore, when peeling a surface protective film from an optical film as an adherend, in order to prevent a defect caused by a high peeling static voltage, a method for suppressing the peeling static voltage to a low level has been proposed. A surface protective film of an adhesive layer containing an antistatic agent.

For example, Patent Document 1 discloses a surface protective film using a binder composed of an alkyltrimethylammonium salt, a hydroxyl-containing acrylic polymer, and a polyisocyanate.

In addition, Patent Document 2 discloses an adhesive composition composed of an ionic liquid and an acrylic polymer having an acid value of 1.0 or less, and an adhesive sheet using the adhesive composition.

In addition, Patent Document 3 discloses an adhesive composition and a surface protective film using the adhesive composition. The adhesive composition is treated with an acrylic polymer, a polyether polyol compound, and an anion-adsorbing compound. Alkali metal salt.

In addition, Patent Document 4 discloses an adhesive composition and a surface protection film using the adhesive composition. The adhesive composition consists of an ionic liquid, an alkali metal salt, and a glass transition temperature of 0 ° C. It consists of the following polymers.

In addition, Patent Documents 5 and 6 disclose mixing a polyether-modified silicone resin with an adhesive layer of a surface protective film.

Prior art literature Patent literature

Patent Document 1: Japanese Patent Application Laid-Open No. 2005-131957

Patent Document 2: Japanese Patent Application Laid-Open No. 2005-330464

Patent Document 3: Japanese Patent Application Laid-Open No. 2005-314476

Patent Document 4: Japanese Patent Application Laid-Open No. 2006-152235

Patent Document 5: Japanese Patent Application Laid-Open No. 2009-275128

Patent Document 6: Patent No. 4537450

In the aforementioned Patent Documents 1 to 4, although an antistatic agent is added to the inside of the adhesive layer, the thicker the adhesive layer or the longer it adheres to the adherend, the longer the surface protective film is adhered to. The greater the amount of antistatic agent transferred from the adhesive layer to the adherend in the adherend. In addition, in optical films such as LR (Low Reflective) polarizers and AG (Anti Glare) -LR polarizers, the surface of the optical film is protected against contamination by silicone resin or fluorine compounds. Treatment, the peeling static voltage when the surface protective film for such an optical film is peeled from the optical film as an adherend is changed high.

In addition, when polyether-modified silicone resin is mixed in the adhesive layer described in Patent Documents 5 and 6, it is difficult to finely adjust the adhesive force of the surface protective film. In addition, since the polyether modified silicone resin is mixed in the adhesive layer, if the conditions for applying the adhesive composition to the substrate film and drying are changed, the surface of the adhesive layer having the surface protective film is formed. The characteristics have changed subtly. Furthermore, from the viewpoint of protecting the surface of the optical film, the thickness of the adhesive layer cannot be made extremely thin. Therefore, it is necessary to increase the amount of the polyether modified silicone resin mixed in the adhesive layer according to the thickness of the adhesive layer. As a result, the surface of the adherend is liable to be contaminated, and the contamination of the adhesive force or the adherend takes time. Variety.

In recent years, with the spread of 3D displays (stereoscopic displays), a patterned retardation (FPR) film may be bonded to the surface of an optical film such as a polarizing plate. After peeling off the surface protection film attached to the surface of an optical film such as a polarizing plate, the FPR film is attached. However, if the surface of an optical film such as a polarizing plate is contaminated with an adhesive or an antistatic agent for a surface protection film, there is a problem that it is difficult to adhere the FPR film. Therefore, a surface protection film for this purpose requires a film with less contamination to the adherend.

On the other hand, in some liquid crystal panel manufacturers, as a method for evaluating the contamination of the adherend by the surface protective film, the following method is adopted. First, the surface protective film attached to an optical film such as a polarizing plate is peeled off. After attaching again in a state with air bubbles mixed therein, and performing heat treatment under predetermined conditions, the surface protective film was peeled off, and the surface of the adherend was observed. In this evaluation method, even if the surface of the adherend is contaminated in a small amount, if there is a difference in the surface contamination of the adherend in the part where the air bubbles are mixed and the part of the surface protective film that is in contact with the adhesive, the air bubbles Traces (sometimes referred to as bubble patches) remain. Therefore, as an evaluation method of the contamination property to the surface of an adherend, it becomes a very strict evaluation method. In recent years, a surface protective film has been required, and even if the surface protective film is determined by such a strict evaluation method, there is no problem in the contamination of the surface of the adherend. However, conventionally, a surface protection film using an adhesive layer containing an antistatic agent has been difficult to solve this technical problem.

Therefore, there is a need for a surface protection film, which is used in an optical film, has very little pollution to an adherend, and does not change the contamination of the adherend with time. Furthermore, there is a need for a surface protection film capable of suppressing the peeling static voltage when peeling from an adherend to be low.

The inventors of the present application have conducted earnest research in order to solve these technical problems.

In order to reduce the contamination of the adherend and minimize the change with time in antistatic performance, it is necessary to reduce the amount of the antistatic agent presumed to cause contamination of the adherend. However, when the amount of the antistatic agent to be added is reduced, the peeling static voltage when the surface protective film is peeled from the adherend increases. The inventors of the present application have studied a method for suppressing the peeling static voltage when the surface protective film is peeled from the adherend to be low without increasing the absolute amount of the antistatic agent. As a result, it was found that instead of adding an antistatic agent to the adhesive composition and mixing it to form an adhesive layer, after applying, drying, and laminating the adhesive composition, the adhesive layer was applied with an appropriate amount on the surface of the adhesive layer. The antistatic agent component can suppress the peeling static voltage when the surface protective film is peeled from the optical film as an adherend to be low, and completed the present invention.

The present invention has been made in consideration of the above circumstances, and the technical problems are In order to provide an anti-static surface protection film, it has less pollution to the adherend, and does not deteriorate with time, and has excellent peeling anti-static performance.

In the antistatic surface protection film of the present invention, after the adhesive composition is coated and dried, and an adhesive layer is laminated, an antistatic agent layer containing an antistatic agent material is formed on the surface of the adhesive layer. Therefore, the technical idea of the present invention is to suppress the peeling static voltage when peeling off the optical film as an adherend while suppressing the contamination of the adherend to a low contamination property.

In order to solve the above-mentioned technical problems, the present invention provides an antistatic surface protection film, characterized in that an antistatic agent-free adhesive layer and an antistatic agent are sequentially laminated on one surface of a substrate film formed of a transparent resin. An electrostatic agent layer and a release film subjected to a release treatment.

The antistatic agent layer preferably contains one selected from the group consisting of an alkali metal salt and an ionic compound.

The antistatic agent-free adhesive layer is preferably formed using an acrylic adhesive composition.

In addition, the thickness of the antistatic agent layer is preferably 0.01 to 0.3 μm .

The antistatic surface protection film of the present invention has less pollution to the adherend, and its low pollution to the adherend does not change over time. In addition, according to the present invention, it is possible to provide an antistatic surface protective film which is used for optical applications in which the surface of an adherend such as an LR polarizer or an AG-LR polarizer is subjected to antifouling treatment through a silicone resin compound or a fluorine compound. Film, it is also possible to suppress the peeling static voltage generated when the antistatic surface protection film is peeled from the adherend to be low, Degraded over time and has excellent peeling antistatic performance.

According to the antistatic surface protective film of the present invention, since the surface of the optical film can be reliably protected, an improvement in productivity and an improvement in yield can be expected.

1‧‧‧ substrate film

2‧‧‧ Adhesive layer

3‧‧‧Antistatic agent layer

4‧‧‧ peeling film

5‧‧‧ Optical Elements

10‧‧‧Anti-static surface protective film

11‧‧‧ peeled off the anti-static surface protective film

20‧‧‧ Optical element with anti-static surface protective film

FIG. 1 is a schematic cross-sectional view of an antistatic surface protective film of the present invention; FIG. 2 is a cross-sectional view illustrating a state where a release film is peeled from the antistatic surface protective film of the present invention; A cross-sectional view of an embodiment of an antistatic surface protective film attached to an optical element.

Hereinafter, this invention is demonstrated in detail based on embodiment.

FIG. 1 is a schematic cross-sectional view of an antistatic surface protection film of the present invention. This antistatic surface protection film 10 has an adhesive layer 2 containing no antistatic agent on the surface of one surface of a transparent base film 1. An antistatic agent layer 3 containing an antistatic agent material is formed on the surface of the adhesive layer 2, and a release film 4 subjected to a peeling treatment is bonded to the surface of the antistatic agent layer 3.

As the base film 1 used for the antistatic surface protection film 10 of the present invention, a base film made of a resin having transparency and flexibility is used. In this way, the appearance inspection of the optical element can be performed in a state where the antistatic surface protective film is bonded to the optical element as an adherend. As the transparent resin film used as the base film 1, polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and polybutylene terephthalate are suitably used. Polyester films such as glycol esters. In addition to polyester film, as long as it has the required strength and has optical characteristics A film made of other resins can also be used. The base film 1 may be a non-stretched film, or may be a uniaxially or biaxially stretched film. The stretching ratio of the stretched film and the alignment angle in the axial direction formed by the crystallization of the stretched film may be controlled to specific values.

The thickness of the base film 1 used in the antistatic surface protection film 10 of the present invention is not particularly limited, and for example, a thickness of about 12 to 100 μm is preferred. Furthermore, the thickness of the base film 1 is more preferably about 20 to 50 μm , and in this case, it is easy to handle.

In addition, if necessary, an antifouling layer, an antistatic layer, a hard coat layer, or the like that prevents surface contamination can be provided on the opposite side of the surface on which the adhesive layer 2 is formed on the base film 1. In addition, the surface of the base film 1 may be subjected to an easy-adhesion treatment such as surface modification via corona discharge and application of a tackifier.

In addition, as long as the adhesive layer 2 used in the antistatic surface protection film 10 of the present invention is adhered to the surface of the adherend to protect the adherend, it can be simply peeled off from the adherend and it is difficult to contaminate the adhered The binder is not particularly limited as long as it is a binder. However, in consideration of durability after bonding to an optical film, it is preferable to form an adhesive layer using an acrylic adhesive composition obtained by crosslinking a (meth) acrylate copolymer.

Examples of the (meth) acrylate copolymer include a main monomer such as n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, and isononyl acrylate, and acrylonitrile and vinyl acetate. , Comonomers such as methyl methacrylate, ethyl acrylate, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, N-hydroxymethacrylamide, etc. Copolymer made from copolymerizing monomers. (Meth) acrylic The acrylate copolymer may have both a main monomer and a comonomer as (meth) acrylates, and as a comonomer, it may contain one or more monomers other than (meth) acrylates.

In the (meth) acrylate copolymer, a compound containing a polyoxyalkylene group may be copolymerized or mixed. Examples of the compound containing a copolymerizable polyoxyalkylene group include polyethylene glycol (400) monoacrylate, polyethylene glycol (400) monomethacrylate, and methoxypolyethylene glycol (400) acrylic acid. Esters, methoxy polyethylene glycol (400) methacrylate, polypropylene glycol (400) monoacrylate, polypropylene glycol (400) monomethacrylate, methoxy polypropylene glycol (400) acrylate, methoxy Polypropylene glycol (400) methacrylate and the like. By copolymerizing these polyoxyalkylene group-containing monomers with the main monomer or functional monomer of the (meth) acrylate copolymer, it is possible to obtain a binder composed of a polyoxyalkylene group-containing copolymer.

The polyoxyalkylene group-containing compound that can be mixed in the (meth) acrylate copolymer is preferably a (meth) acrylate copolymer containing a polyoxyalkylene group, and more preferably a (meth) acrylate containing a polyoxyalkylene group. Polymers) of acrylic monomers. For example, polyethylene glycol (400) monoacrylate, polyethylene glycol (400) monomethacrylate, methoxy polyethylene glycol (400) acrylate, and methoxy polyethylene glycol ( 400) methacrylate, polypropylene glycol (400) monoacrylate, polypropylene glycol (400) monomethacrylate, methoxy polypropylene glycol (400) acrylate, methoxy polypropylene glycol (400) methacrylate And other polymers. By mixing these polyoxyalkylene group-containing compounds with the (meth) acrylate copolymer, a binder to which a polyoxyalkylene group-containing compound is added can be obtained.

Examples of the curing agent added to the adhesive layer 2 include a isocyanate compound, an epoxy compound, a melamine compound, and a metal chelate as a crosslinking agent that crosslinks the (meth) acrylate copolymer. Examples of the thickener include rosin, coumarone indene, terpene, petroleum, and phenol.

The thickness of the adhesive layer 2 used in the antistatic surface protection film 10 of the present invention is not particularly limited. For example, the thickness is preferably about 5 to 40 μm , and more preferably about 10 to 30 μm .

As a method for forming the adhesive layer 2 on the surface of the base film 1, a known method may be used. Specifically, a reverse coating method, a comma coating method, or a gravure coating method may be used. Gravure coating, slot die coating, Meyer bar coating, air knife coating and other known coating methods are known.

The antistatic agent-containing material used to form the antistatic agent layer 3 used in the antistatic surface protective film 10 of the present invention includes an antistatic agent alone, a mixture of an antistatic agent, and various resins.

Examples of the antistatic agent include surfactants, ionic liquids, alkali metal salts, metal acid compounds, metal particles, conductive polymers, carbon, carbon nanotubes, and the like. From transparency and (meth) acrylic acid, In consideration of the affinity of the polymer-based polymer, surfactants, ionic compounds, and alkali metal salts are preferred.

Examples of the resin used in the mixture of the antistatic agent and various resins include polyester resins, polyamide resins, polyurethane resins, polyolefin resins, polyvinyl butyral resins, and polyvinyl alcohol resins. , Polyvinyl acetate resin, cellulose resin, silicone resin, fluorine resin, etc.

Examples of the surfactant include nonionic, cationic, anionic, and amphoteric types. Examples of the nonionic surfactant include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and polyoxyethylene. Ethylene fatty acid esters, glycerin fatty acid esters, propylene glycol fatty acid esters, polyoxyalkylene modified silicone resins, and the like.

Examples of the cationic surfactant include alkyltrimethylammonium salts, dialkyldimethylammonium salts, and alkylbenzyldimethylammonium salts.

Examples of the anionic surfactant include monoalkyl sulfates, alkyl polyoxyethylene sulfates, alkylbenzene sulfonates, and monoalkyl phosphates.

Examples of the amphoteric surfactant include alkyldimethylamine oxide, alkylcarboxybetaine, and the like.

Ionic compounds refer to ionic liquids composed of anions and cations, which are liquid at normal temperature, and ionic solids which are solid at normal temperature. Examples of the cationic moiety include organic cations and inorganic cations, and examples include cyclic sulfonium ions such as imidazolium ions, pyridinium ions, ammonium ions, sulfonium ions, and sulfonium ions. Further, as the anionic moiety include an organic anion or inorganic anion, _{e.g., C n H 2n + 1 COO} -, C n F 2n + 1 COO -, NO 3 -, C n F 2n + 1 SO 3 -, ( _{C n F 2n + 1 SO 2} ) 2 N -, (C n F 2n + 1 SO 2) 3 C -, PO 4 3-, AlCl 4 -, Al 2 Cl 7 -, ClO 4 -, BF 4 -, ^{_{PF 6 -, AsF 6 -,}} SbF 6 - and so on. In the above formula, the subscript n is an integer of 0 or more. In the case of n = 0, it is equivalent to HCOO ⁻ , (FSO ₂ ) ₂ N ⁻ and the like.

Examples of the alkali metal salt include metal salts formed of lithium, sodium, and potassium. Specifically, for example, can be suitably used Li ^+, Na ^+, K ⁺ cations and ^{Cl -, Br -, I -} , BF 4 -, PF 6 -, SCN -, ClO 4 -, CF 3 SO 3 _{^{-, (FSO 2) 2 N}} -, (CF 3 SO 2) 2 N -, (C 2 F 5 SO 2) 2 N -, (CF 3 SO 2) 3 C - anion of the metal salt thereof. Among them, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ , Li (FSO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₂ N, and Li (C ₂ F ₅ SO) are particularly preferably used. ₂ ) Lithium salts such as ₂ N and Li (CF ₃ SO ₂ ) ₃ C. These alkali metal salts may be used singly or in combination of two or more kinds. In order to stabilize the ionic substance, a compound containing a polyoxywestyl structure may be added.

The thickness of the dried coating film of the antistatic agent layer 3 may be determined in consideration of the type of the antistatic agent, its antistatic property, and contamination by the adherend, but it is preferably 0.3 μm or less. When the thickness of the antistatic agent layer 3 exceeds 0.3 μm, when the surface protective film is bonded to the adherend, it becomes difficult for the components of the adhesive composition to appear between the surface protective film and the resin formed with the antistatic agent layer. Since the adhesive force of the adhesive layer 2 does not reach a predetermined value on the interface of the adherend, it is not preferable. The thickness of the antistatic agent layer 3 is, for example, 0.01 to 0.3 μm.

The antistatic surface protection film 10 (specifically, the antistatic surface protection film 11 from which the release film is peeled off as shown in FIG. 2) is peeled from the adherend, and the antistatic surface is protected from the viewpoint of excellent operability. The peeling strength (adhesive force) when the film 10 is peeled from the surface of the adherend is preferably a weak adhesive force of about 0.03 to 0.3 N / 25 mm.

In addition, from the viewpoint of excellent operability when peeling the release film 4 from the antistatic surface protective film 10, the peel force when peeling the release film 4 from the antistatic agent layer 3 is preferably 0.2 N / 50 mm or less.

In addition, in the antistatic surface protective film 10 of the present invention, the method of forming the antistatic agent layer 3 on the surface of the adhesive layer 2 is not particularly limited. example For example, the following methods can be enumerated: (1) a method of making the release agent layer of the release film 4 contain the above-mentioned antistatic agent-containing material, and transferring the release film 4 to the adhesive layer 2 when the release film 4 is bonded to the adhesive layer 2; (2) a method of printing the above-mentioned antistatic agent-containing material on the surface of the adhesive layer 2; (3) a method of applying the above-mentioned antistatic agent-containing material on the surface of the adhesive layer 2 and the like. The antistatic agent-containing material may be printed or coated uniformly, or may be printed or coated with a specific pattern. It is only necessary to determine the adhesion force of the adhesive layer to the adherend of the antistatic surface protective film. The printing or coating method of the antistatic agent-containing material can be performed by a known method.

The resin used for the release film 4 used in the antistatic surface protective film 10 of the present invention shown in FIG. 1 is not particularly limited. As the release film 4, for example, one surface of a resin film such as a polyester film, a polyimide film, a polyethylene film, a polypropylene film, or a polyimide film is subjected to a silicone resin-based release agent or a long-chain alkane-containing agent. A release film treated with a release agent such as a base resin, a fluororesin, or a release film formed by releasing a resin having a release property such as a polyethylene resin, a polypropylene resin, a polymethylpentene resin, or a fluororesin.

The thickness of the release film is not particularly limited. For example, a thickness of about 12 to 100 μm is preferable, and a thickness of about 20 to 50 μm is easy to handle, so it is more preferable.

Fig. 2 is a cross-sectional view showing a state where the release film is peeled from the antistatic surface protection film of the present invention. In the antistatic surface protection film 11 in which the release film is peeled off as shown in FIG. 2, an antistatic agent layer 3 is provided on the surface of the adhesive layer 2.

Fig. 3 shows the bonding of the antistatic surface protective film of the present invention. Sectional view of an embodiment on an optical element.

The antistatic surface protective film 10 of the present invention is peeled off the release film 4 after the peeling treatment, and the antistatic agent layer 3 is exposed (the antistatic surface protective film 11 in FIG. 2), and the antistatic surface protective film 10 is pasted through the antistatic agent layer 3. It is attached to the optical element 5 as an adherend.

That is, FIG. 3 shows the optical element 20 to which the antistatic surface protective film 11 is bonded in a state where the release film 4 is peeled from the antistatic surface protective film 10 of the present invention. Examples of the optical element include optical films such as a polarizing plate, a retardation plate, a lens film, a polarizing plate also serving as a retardation plate, and a polarizing plate also serving as a lens film. Such an optical element can be used as a structural element, such as a liquid crystal display device, such as a liquid crystal display panel, and various optical devices, such as various measuring instruments. Examples of the optical element include optical films such as an antireflection film, a hard coat film, and a transparent conductive film for a touch panel. In particular, it can be suitably used as optical materials such as low-reflection-treated polarizing plates (LR polarizing plates) and anti-glare low-reflection processing polarizing plates (AG-LR polarizing plates) that have been subjected to anti-pollution treatment such as silicone resin or fluorine compounds. Use a film with an antistatic surface protective film attached to the anti-contamination surface.

When the antistatic surface protection film 11 in a state where the release film 4 is peeled from the antistatic surface protection film 10 of the present invention is peeled off from the optical element (optical film) as an adherend, the peeling static voltage can be sufficiently reduced. . Therefore, there is no need to worry about damaging circuit elements such as a driving IC, a TFT element, and a gate line driving circuit, and it is possible to improve the production efficiency in the step of manufacturing the liquid crystal display panel and ensure the reliability of the production step.

Examples

Next, the present invention will be further described through examples.

(Example 1) (Production of antistatic surface protective film)

It is composed of a copolymer of 80 parts by weight of 2-ethylhexyl acrylate, 17 parts by weight of methoxypolyethylene glycol (400) methacrylate, and 3 parts by weight of 2-hydroxyethyl acrylate with respect to 100 parts by weight. A 40% ethyl acetate solution of an adhesive was stirred and mixed with 2 parts by weight of an isocyanate-based curing agent (CORONATE (registered trademark) HX manufactured by Tosoh Corporation) to prepare an adhesive composition. On the surface of the polyethylene terephthalate film having a thickness of 38 μm, the prepared adhesive composition was applied with a coating device so that the thickness of the dried adhesive layer was 20 μm. Then, it heat-dried using 100 degreeC hot air circulation type oven for 3 minutes, and obtained the adhesive film. Then, on the surface of the adhesive layer, an ethyl acetate solution of Lithium bis (trifluoromethanesulfonyl) imide as an antistatic agent was coated with a Meyer bar and dried. The thickness of the antistatic agent layer was changed to 0.1 μm, and then heated and dried in a hot air circulation oven at 100 ° C. for 2 minutes to prepare a sample having an antistatic agent layer formed on the surface of the adhesive layer. A release film (Diafoil MRF38, manufactured by Mitsubishi Resins Co., Ltd.) was attached to the surface of the antistatic agent layer of the sample, and a surface of a polyethylene terephthalate film having a thickness of 38 μm was treated with a silicone resin release agent. As a result, an antistatic surface protection film of Example 1 was obtained.

(Example 2)

70 parts by weight of 2-ethylhexyl acrylate, 20 parts by weight of butyl acrylate, 7 parts by weight of methoxypolyethylene glycol (400) methacrylate, and 2 parts by weight of 2-hydroxyethyl with respect to 100 parts by weight. A 40% ethyl acetate solution of a binder composed of a copolymer of acrylic acrylate and 1 part by weight of an isocyanate-based curing agent (CORONATE (registered trademark) HX manufactured by Tosoh Corporation) was stirred and mixed to prepare a binder composition. On the surface of the polyethylene terephthalate film having a thickness of 38 μm , the prepared adhesive composition was applied with a coating device so that the thickness of the dried adhesive layer was 20 μm . Then, it heat-dried using 100 degreeC hot air circulation type oven for 3 minutes, and obtained the adhesive film. Then, the surface of the adhesive layer was coated with an ethyl acetate solution of lithium bis (fluorosulfonyl) imide as an antistatic agent using a wire rod No. 4 to make the dried antistatic agent layer. The thickness was 0.05 μm , and then heated and dried in a hot air circulation oven at 100 ° C. for 2 minutes to prepare a sample having an antistatic agent layer formed on the surface of the adhesive layer. A release film (Diafoil MRF38, manufactured by Mitsubishi Resins Co., Ltd.) was attached to the surface of the sample's antistatic agent layer, and the surface of the polyethylene terephthalate film with a thickness of 38 μm was peeled off by a silicone Agent treatment) to obtain the antistatic surface protection film of Example 2.

(Example 3)

An antistatic surface protection film of Example 3 was obtained in the same manner as in Example 1, except that the dried thickness of the antistatic agent layer of Example 1 was set to 0.3 μm .

(Example 4)

Except that the antistatic agent in Example 1 was changed to tri-n-butylmethylammonium bis- (trifluoromethanesulfonyl) imide (manufactured by 3M Japan, product number: FC-4400), In the same manner as in Example 1, an antistatic surface protection film of Example 4 was obtained.

(Comparative example 1)

In the adhesive composition of Example 1, the antistatic agent of Example 1 was mixed in such a manner that the solid content ratio was 100: 1.5, and the adhesive composition mixed with the antistatic agent was applied to dry the adhesive layer. The thickness was 20 μm , and instead of laminating the antistatic agent layer on the adhesive layer, the antistatic surface protective film of Comparative Example 1 was obtained in the same manner as in Example 1.

(Comparative example 2)

A surface protection film of Comparative Example 2 was obtained in the same manner as in Example 1 except that the antistatic agent layer was not provided.

(Comparative example 3)

An antistatic surface protection film of Comparative Example 3 was obtained in the same manner as in Example 1 except that the thickness of the antistatic agent layer after drying was 0.5 μm .

The methods and results of the evaluation tests are shown below.

<Method for measuring peeling force of release film>

A sample of the antistatic surface protective film was cut into a width of 50 mm and a length of 150 mm. In a test environment of 23 ° C. × 50% RH, a tensile tester was used at a peeling speed of 300 mm / min in a direction of 180 ° to measure the strength when the release film was peeled from the antistatic agent layer, and this was taken as the peel. Film peeling force (N / 50mm).

<Method for measuring surface resistivity of antistatic agent surface>

After the release film was peeled off from the sample of the antistatic surface protection film, the antistatic was measured using a high-resistance resistivity meter (Hiresta (registered trademark) -UP by Analytical Technology, Inc.) under a voltage of 100V and a measurement time of 30 seconds. Surface resistivity of the surface of the agent layer.

<Method for measuring the adhesion of antistatic surface protective film>

Using a laminator, an anti-glare low-reflection polarizer (AG-LR polarizer) was bonded to the surface of the glass plate. Then, an antistatic surface protective film having a width of 25 mm was cut and bonded on the surface of the polarizing plate, and then stored in a test environment at 23 ° C. × 50% RH for one day. Then, using a tensile tester, the strength at the time of peeling the antistatic surface protective film was measured at a peeling speed of 300 mm / min in a direction of 180 °, and this was used as the adhesive force (N / 25 mm).

<Measurement method of peeling static voltage of antistatic surface protective film>

Using a laminator, an anti-glare low-reflection polarizer (AG-LR polarizer) was bonded to the surface of the glass plate. Then, an antistatic surface protective film with a width of 25 mm was cut and bonded to the surface of the polarizing plate via an antistatic agent layer, and then stored in a test environment at 23 ° C. 50% RH for one day. Then, a high-speed peel tester (manufactured by Tester Industries) was used to peel off the antistatic surface protective film at a peeling speed of 40 m per minute, and the surface potential of the surface of the polarizing plate was measured every 10 ms using a surface potentiometer (manufactured by Keyence) The maximum value of the absolute value of the surface potential at this time was taken as the peeling static voltage (kV).

<Method for confirming surface contamination of antistatic surface protective film>

Using a laminator, an anti-glare low-reflection polarizer (AG-LR polarizer) was bonded to the surface of the glass plate. Then, an antistatic surface protective film having a width of 25 mm was cut and bonded on the surface of the polarizing plate via an antistatic agent layer, and then stored in a test environment at 23 ° C. × 50% RH for 3 days and 30 days. Then, the antistatic surface protective film was peeled off, and the contamination of the surface of the polarizing plate was visually observed. As a criterion for determining the surface contamination, a case where no pollution was transferred on the polarizing plate was rated (○), and a case where pollution was transferred on the polarizing plate was rated (×).

The measurement results of the obtained antistatic surface protective films of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Tables 1 and 2. "LiTFSI" means lithium bistrifluoromethanesulfonylimide, "LiFSI" means lithium bisfluorosulfimide lithium, and "FC-4400" means bistrifluoromethanesulfonylimine tri-n-butylmethylammonium. In addition, “4.3E11” in the column of the surface resistivity of the surface of the antistatic agent layer means 4.3 × 10 ¹¹ , and “Over-range” means that the surface resistivity (Ω / □) exceeds the upper measurement limit. The value (1.0 × 10 ¹³ or more) cannot be measured.

According to the measurement results shown in Tables 1 and 2, the following situations are known: The antistatic surface protection films of Examples 1 to 4 of the present invention have a moderate adhesive force even if they are bonded through an antistatic agent layer, have no pollution to the surface of the adherend, and remove the antistatic surface protection film from the adherend. The peeling static voltage at the time of the peeling is low.

On the other hand, the surface protection film of Comparative Example 1 in which the antistatic agent was uniformly mixed in the adhesive layer had a low peeling static voltage when the surface protection film was peeled from the adherend, but it was good, but after 30 days of storage, The contamination of adherends deteriorates over time. In addition, the surface protection film of Comparative Example 2 in which the antistatic agent layer was not provided on the surface of the adhesive layer had a high peeling static voltage when the surface protection film was peeled from the adherend. Furthermore, in Comparative Example 3 in which the thickness of the antistatic agent layer was increased, the peeling static voltage when the surface protective film was peeled from the adherend was low and good, but the contamination of the adherend after peeling increased.

Industrial applicability

The antistatic surface protection film of the present invention can be used to protect the surface of an optical element or the like in an optical film such as a polarizing plate, a retardation plate, a lens film for a display, or other various optical elements. In particular, when it is used as an antistatic surface protective film for an optical film such as an LR polarizer or an AG-LR polarizer that has been subjected to antifouling treatment with a silicone resin compound or a fluorine compound on the surface, When the body is peeled off, the amount of static electricity generated can be reduced.

The antistatic surface protective film of the present invention has less contamination to the adherend, and further, it does not deteriorate over time, and has excellent peeling antistatic performance. Therefore, the antistatic surface protection film of the present invention can improve the yield of production steps of various optical elements and the like, and has great industrial application value.

Claims (2)

An antistatic surface protection film, characterized in that it is a layer of an antistatic agent-free adhesive layer, an antistatic agent layer, and An antistatic surface protective film of a release film. The antistatic agent-free adhesive layer is formed using an acrylic adhesive composition. The antistatic layer is formed on the entire surface of the adhesive layer. The thickness of the antistatic agent layer is 0.01 to 0.3 μm, and one side of the resin film of the release film is treated with a release agent so that the release film has excellent operability when peeled from the antistatic surface protection film. The antistatic surface protection film according to item 1 of the scope of the patent application, wherein the antistatic agent layer contains one selected from the group consisting of an alkali metal salt and an ionic compound.