TW201722733A - Surface protection film and optical component to which the surface protection film is attached - Google Patents

Abstract

The present invention provides a surface protective film and an optical element using the surface protective film. The surface protective film can be adhered to an optical film which has bumpy surface. The surface protective film contaminates bonding material fewer, the low contamination to bonding materials does not change over time, and the excellent antistatic peeling performance does not degrade over time. A surface protective film 5 is composed by forming a peeling agent layer 2 on a surface of a substrate film 1 having a transparent resin, and forming an adhesive agent layer 4 on another surface of the substrate film 1. The peeling agent layer 2 contains a silicon type peeling agent and an antistatic agent 3 composed of a alkali metal salt. The component of the antistatic agent 3 composed of the alkali metal salt contained in the peeling agent layer 2 only exists in a surface of the adhesive agent layer 4.

Description

Surface protection film and optical component to which the surface protection film is attached

The present invention relates to a surface protective film that is bonded to a surface of an optical member (hereinafter sometimes referred to as an optical film). More specifically, a surface protective film and an optical member using the surface protective film are provided, and the surface protective film has less contamination to the adherend, and the contamination of the adherend does not change with time. Further, the present invention provides a peeling surface protection even if a constituent member of a polarizing plate that replaces an optical member (changed from a TAC film to an acrylic film or a polyester film, and an aqueous adhesive to an ultraviolet curing type adhesive) is provided. A surface protective film having a low peeling static voltage at the time of filming, and an optical member to which the surface protective film is bonded.

Further, the optical member of the present invention refers to a polarizing plate, a phase difference plate, a lens film for a display, and the like.

When manufacturing and transporting optical films such as a polarizing film, a retardation film, a screen film for a display, an antireflection film, a hard coat film, and a transparent conductive film for a touch panel, and an optical product such as a display using the optical film The surface protective film is bonded to the surface of the optical film to prevent surface dirt and scratches in the subsequent steps. In order to save the work of peeling off the surface protective film and to improve the work efficiency, The visual inspection of the optical film as a product was directly performed in a state in which the surface protective film was bonded to the optical film.

In the manufacturing step of the conventional optical product, in order to prevent the adhesion of scratches or dirt, a surface protective film provided with an adhesive layer on one surface of the base film is usually used. The surface protective film is bonded to the optical film via a microadhesive adhesive layer. The reason why the adhesive layer is slightly adhered is that when the used surface protective film is peeled off from the surface of the optical film, it can be easily peeled off, and the adhesive does not adhere to the product as the adherend. On the film for optics (the so-called prevention of the generation of residual glue).

In recent years, in the production process of the liquid crystal display panel, although the number of occurrences is small, the peeling static voltage generated when the surface protective film attached to the optical film is peeled off is removed, and the liquid crystal is controlled. The circuit component such as the driver IC on the display screen of the display is damaged or the alignment of the liquid crystal molecules is damaged.

Further, in order to reduce the power consumption of the liquid crystal display panel, the driving voltage of the liquid crystal material is lowered, and the breakdown voltage of the driving IC is also lowered. Recently, the peeling static voltage is required to be in the range of +0.7 kV to -0.7 kV.

In addition, a conventional polarizing plate is bonded to a triacetyl cellulose film (TAC) for protecting a polarizer by water-based adhesive on both sides of a polarizer composed of polyvinyl alcohol (PVA) impregnated with iodine. Film), a polarizing plate is produced, and in recent years, as an alternative to the TAC film, a polarizing plate using an acrylic film, a cyclic polyolefin film or a polyester film, or an ultraviolet curing type adhesive is used instead of water. Polarizer for the adhesive. The constituent materials used for the polarizing plate vary, and thus the following problems occur: peeling static voltage generated when peeling off the surface protective film It is higher than when using a polarizing plate of a conventional structure.

In addition, in recent years, along with the spread of 3D displays (stereoscopic displays), FPR (Film Patterned Retarder) films have been bonded to the surface of an optical film such as a polarizing plate. After the surface protective film adhered to the surface of the optical film such as a polarizing plate is peeled off, the FPR film is bonded. However, if the surface of the optical film such as a polarizing plate is contaminated by an adhesive or an antistatic agent used for the surface protective film, there is a problem that the FPR film is hard to be bonded. Therefore, the surface protective film for this use is required to have less contamination of the adherend.

On the other hand, in some liquid crystal panel manufacturers, as a method for evaluating the contamination of an adherend by a surface protective film, a method of temporarily peeling off a surface protective film bonded to an optical film such as a polarizing plate and mixing bubbles therein is employed. In the state of being re-applied, heat treatment is performed under predetermined conditions, and then the surface protective film is peeled off to observe the surface of the adherend. In this evaluation method, even if the surface of the adherend is contaminated with a small amount, there is a difference in the surface contamination of the adherend between the portion where the bubble is mixed and the portion where the adhesive of the surface protective film is adhered, as a trace of the bubble. (sometimes called bubble spots) and remains. Therefore, as a method of evaluating the contamination of the surface of the adherend, it is a very strict evaluation method. In recent years, a surface protective film which is judged to be acceptable by the above-described strict evaluation method and which has little contamination on the surface of an adherend is sought.

In order to prevent the defect caused by the high peeling static voltage generated when the surface protective film is peeled off from the adherend after the surface protective film is bonded to the optical film as the adherend, a method for A surface protective film using an adhesive layer containing an antistatic agent having a low peeling static voltage suppressed.

For example, in Patent Document 1, a use of an alkane is disclosed A surface protective film of an adhesive composed of a methic acid ammonium salt, a hydroxyl group-containing acrylic polymer, and a polyisocyanate.

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

Further, Patent Document 3 discloses an adhesive composition comprising an alkali metal salt treated with an acrylic polymer, a polyether polyol compound, or an anion-adsorbing compound, and a surface protective film using the composition.

Further, Patent Document 4 discloses an adhesive composition comprising an ionic liquid, an alkali metal salt, a polymer having a glass transition temperature of 0 ° C or lower, and a surface protective film using the composition.

Prior art literature

Patent literature

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

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

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

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

In the surface protection film described in the above Patent Documents 1 to 4, an antistatic agent is added to the inside of the pressure-sensitive adhesive layer. Therefore, the thicker the thickness of the adhesive layer or the longer the elapsed time after adhering to the adherend, the transfer of the antistatic agent from the adhesive layer to the adherend for the adherend to which the surface protective film is bonded. Increase in quantity More tendencies. In addition, when the amount of the antistatic agent transferred to the adherend is increased, the appearance quality of the optical film as the adherend may be lowered, and the adhesion of the FPR film when the FPR film is bonded may be lowered.

As described above, in order to reduce the temporal change of the antistatic agent from the adhesive layer to the adherend, if the thickness of the adhesive layer is made thin, other problems occur. For example, when an optical film having irregularities on its surface, such as a polarizing plate subjected to anti-glare treatment for preventing glare, is used, it is difficult for the adhesive layer to follow the irregularities on the surface of the optical film to mix air bubbles; Since the adhesion area between the optical film and the adhesive layer is reduced, the adhesion is lowered, and the surface protective film floats or peels off during use.

Further, in order to reduce the change of the antistatic agent from the adhesive layer to the adherend over time, if the amount of the antistatic agent added to the adhesive layer is reduced, the surface protective film is removed from the adherend and removed. When the peeling static voltage is increased, there is a risk that a circuit component such as a driver IC is broken or a alignment of liquid crystal molecules is impaired.

The present invention has been made in view of the above circumstances, and a technical object thereof is to provide a surface protective film that is bonded to a surface of an optical film and an optical member using the surface protective film, and the surface protective film has an optical surface having irregularities on the surface. The film can also be bonded, the contamination to the adherend is very small, and the low contamination of the adherend does not change over time.

Further, an object of the present invention is to provide a component (a change from an TAC film to an acrylic film or a polyester film and an aqueous adhesive to an ultraviolet curable adhesive) even if a component of a polarizing plate as an optical member is replaced. a surface protective film capable of suppressing peeling static voltage when peeling off the surface protective film, and The optical member of the surface protective film was used.

In order to solve the above technical problems, the inventors conducted a careful study. In order to reduce the amount of contamination to the adherend and to reduce the change in the degree of contamination over time, it is necessary to reduce the content of the antistatic agent which is presumed to be a cause of contamination of the adherend. However, when the content of the antistatic agent is reduced, the peeling static voltage when the surface protective film is peeled off from the adherend is increased.

Therefore, the inventors studied a method of suppressing the peeling static voltage when the surface protective film was peeled off from the adherend without increasing the content of the antistatic agent.

The inventors first apply an adhesive composition containing no antistatic agent to one side of a substrate and dry it, layer an adhesive layer, and laminate a release agent layer containing an antistatic agent on the other side of the substrate to prepare a surface protection. membrane. Then, the surface protective film is wound into a roll shape so that the adhesive layer is inside, whereby the component of the antistatic agent contained in the release agent layer is transferred onto the surface of the adhesive layer to form A state existing only on the surface of the adhesive layer. When the surface protective film was temporarily bonded to the optical film as the adherend, the peeling static voltage when peeled off from the adherend was suppressed to be low, and it was difficult to contaminate the adherend, and the present invention was completed.

The surface protective film of the present invention is obtained by applying an adhesive composition containing no antistatic agent to one side of a substrate and drying it, laminating an adhesive layer, and laminating a release agent layer containing an antistatic agent on the other side of the substrate. Thereafter, the surface protective film is wound into a roll shape so that the adhesive layer is inside, whereby the component of the antistatic agent contained in the release agent layer is transferred onto the surface of the adhesive layer. Invention of the present invention In the case where the surface protective film wound in a roll shape is wound up in a roll shape and bonded to the adherend, the contamination of the adherend is suppressed to a low level, and the surface is pressed. When the protective film is peeled off from the optical film as the adherend, the peeling static voltage is suppressed to be low.

In order to solve the above problems, the present invention provides a surface protective film characterized in that a release agent layer is formed on one surface of a base film composed of a resin having transparency, and another substrate film is formed. An adhesive layer is formed on the surface, and the release agent layer contains an antistatic agent composed of an alkali metal salt and an anthrone-based release agent, and the component of the antistatic agent composed of the alkali metal salt contained in the release agent layer exists only On the surface of the adhesive layer.

Further, the adhesive layer is preferably an acrylic adhesive layer containing a crosslinked (meth) acrylate copolymer.

Further, it is preferable that the surface potential when the adhesive layer is peeled off from the optical film as the adherend is +0.7 kV to -0.7 kV.

Further, it is preferable that the base film is wound into a roll shape with the adhesive layer interposed therebetween so that the release agent layer is in contact with the adhesive layer.

Further, the present invention provides an optical member obtained by laminating the surface protective film via the adhesive layer.

The surface protective film of the present invention is a surface protective film that is bonded to the surface of the optical film, and can be bonded to an optical film having irregularities on the surface.

Further, according to the present invention, it is possible to provide a surface protective film which has little contamination to an adherend and which does not change over time with respect to the contamination of the adherend, and an optical member using the surface protective film.

Further, according to the present invention, it is possible to provide a constituent member of a polarizing plate in which an optical member is changed (changing from a TAC film to an acrylic film, a cyclic polyolefin film or a polyester film, and changing from an aqueous adhesive to an ultraviolet curing adhesive) It is also possible to provide a surface protective film which suppresses the peeling static voltage when the surface protective film is peeled off, and an optical member using the surface protective film.

Further, the surface protective film wound in a roll shape according to the present invention is a surface protective film in which a base film is wound into a roll shape with the release agent layer in contact with the adhesive layer, and the adhesive layer is placed inside. The component of the antistatic agent composed of the alkali metal salt is transferred from the release agent layer to the surface of the adhesive layer, and is present only on the surface of the adhesive layer.

In other words, the present invention is characterized in that the surface protective film which is unwound by the surface protective film wound in a roll shape is bonded to the adherend, and the peeling static voltage is lowered when the surface protective film is peeled off from the adherend, and is resistant. Since the peeling static electricity performance changes with time and the contamination to the adherend is small, it is expected that the productivity of the optical member as the adherend can be improved and the yield can be improved.

1‧‧‧Base film

2‧‧‧ Stripper layer

3‧‧‧Antistatic agent

4‧‧‧Adhesive layer

5‧‧‧Surface protection film

6‧‧‧Optical components (optical film)

7‧‧‧Optical parts with surface protection film

10‧‧‧Surface protection film wound into a roll

1 is a schematic cross-sectional view showing a surface protective film wound in a roll state according to the present invention; and FIG. 2 is a view showing a state in which a surface protective film of the present invention is wound into a roll state, and a release agent layer and an adhesive layer are in contact with each other. FIG. 3 is a cross-sectional view showing an embodiment in which the surface protective film of the present invention is bonded to an optical member.

Hereinafter, the present invention will be described in detail based on the embodiments.

Fig. 1 is a schematic cross-sectional view showing a surface protective film 10 wound in a roll state according to the present invention. The surface protection film 10 wound in a roll state shown on the right side of FIG. 1 is a surface protective film (the roll of the surface protection film 5) in which the surface protection film 5 of the present invention is wound into a roll shape with the adhesive layer 4 inside. body). In addition, the left side of FIG. 1 is a schematic cross-sectional view showing the surface protective film 5 which is retracted from the roll shape in the direction of the arrow in the thickness direction.

The surface protective film 5 has a release agent layer 2 containing an antistatic agent 3 composed of an alkali metal salt on one surface of the transparent base film 1, and an adhesive layer is formed on the other surface of the base film 1. Agent layer 4. A release agent layer 2 is provided on one surface of the base film 1, and a surface protection film 5 having an adhesive layer 4 on the other surface of the base film 1 is attached to the adhesive layer 2 with the release agent layer 2 In the manner in which the adhesive layer 4 is wound into a roll inside, the surface protective film 10 in a state of being wound into a roll can be obtained, and the component of the antistatic agent 3 contained in the release agent layer 2 can be transferred. The surface to the adhesive layer 4 exists only on the surface of the adhesive layer 4.

As the base film 1 used for the surface protection film 5 of the present invention, a base film composed of a resin having transparency and flexibility can be used. Thereby, the appearance inspection of the optical member can be performed in a state in which the surface protective film 5 is bonded to the optical member as the adherend. As the film made of the transparent resin used as the base film 1, polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, or the like, can be suitably used. A polyester film such as polybutylene terephthalate. In addition to the polyester film, a film composed of another resin may be used as long as it has required strength and optical suitability. The base film 1 may be a non-stretched film or a film which is uniaxially or biaxially stretched. Further, the stretching ratio of the stretched film and the alignment angle of the axial direction formed by the crystallization of the stretched film Can be controlled to a specific value.

The thickness of the base film 1 for the surface protective film 5 of the present invention is not particularly limited, and is preferably, for example, about 12 to 100 μm, and more preferably about 20 to 75 μm.

Further, an easy adhesion treatment by surface modification of a corona discharge, application of an anchoring agent or the like may be applied to the surface of the base film 1 as needed.

Further, the release agent layer 2 formed on the surface protection film 5 of the present invention is formed using a release agent containing an antistatic agent 3 composed of an alkali metal salt. As the release agent, an anthrone-based release agent is suitably used.

Examples of the anthrone-based release agent include a conventional anthrone-based release agent such as an addition reaction type, a condensation reaction type, a cationic polymerization type, and a radical polymerization type. Examples of commercially available products of the addition reaction type ketone-based release agent include KS-776A, KS-847T, KS-779H, KS-837, KS-778, and KS-830 (Shin-Etsu Chemical Industry Co., Ltd. )), SRX-211, SRX-345, SRX-357, SD7333, SD7220, SD7223, LTC-300B, LTC-350G, LTC-310 (manufactured by Dow Corning Toray Co., Ltd.). Examples of the commercially available product of the condensation reaction type include SRX-290 and SYLOFF-23 (manufactured by Dow Corning Toray Co., Ltd.). Examples of the commercially available product of the cationic polymerization type include TPR-6501, TPR-6500, UV9300, VU9315, UV9430 (manufactured by Momentive Performance Materials), and X62-7622 (manufactured by Shin-Etsu Chemical Co., Ltd.). Examples of the commercially available product of the radical polymerization type include X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.).

The antistatic agent 3 contained in the release agent layer 2 is excellent in dispersibility in the anthrone-based release agent solution and does not inhibit the curing of the anthrone-based release agent. Electrostatic agents are preferred. Further, on the surface of the adhesive layer 4 which is in contact with the release agent layer 2, the component of the antistatic agent 3 contained in the release agent layer 2 is transferred, and the surface of the adhesive layer 4 is provided with an antistatic function, and therefore An antistatic agent which reacts with an anthrone-based release agent is preferred. As such an antistatic agent, an alkali metal salt is suitable.

The alkali metal salt may, for example, be a metal salt composed of lithium, sodium or potassium. Specifically, for example, a cation selected from Li ⁺ , Na ⁺ , K ⁺ and a selected from Cl ^- , Br ^- , I ^- , BF ₄ ^- , PF ₆ ^- , SCN ^- , ClO ₄ ^- , CF ₃ SO may be applied. a metal salt composed of an anion of ₃ ^- , (CF ₃ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- , (CF ₃ SO ₂ ) ₃ C ^- . Among them, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, Li(C ₂ F ₅ SO ₂ ) ₂ N, Li(CF ₃ SO) are especially used. ₂ ) Lithium salts such as ₃ C are preferred. These alkali metal salts may be used singly or in combination of two or more. For the stabilization of the ionic substance, a compound containing a polyoxyalkylene structure may also be added.

The amount of the antistatic agent to be added to the anthrone-based release agent varies depending on the type of the antistatic agent or the affinity with the anthrone-based release agent, but it is conceivable that the anti-static agent is peeled off when the surface protective film is peeled off from the adherend. The static voltage, the contamination of the adherend, and the adhesive properties are set. The mixing ratio (weight ratio) of the anthrone-based release agent to the antistatic agent is, for example, preferably from 5 to 100, based on the solid content of the solid component of the antimony-based release agent. Good for a ratio of 5 to 60. When the solid content of the antistatic agent is less than 5, the amount of the antistatic agent transferred to the surface of the adhesive layer is small, and it is difficult to exhibit the adhesive in the adhesive. Antistatic function. In addition, when the solid content of the antistatic agent is more than 100, the amount of the solid content of the antistatic agent exceeds 100, and the fluorenone is peeled off. The composition of the agent and the antistatic agent are simultaneously transferred to the surface of the adhesive layer, so there is a possibility that the adhesive property of the adhesive is lowered.

The release agent layer 2 is composed of at least an anthrone-based release agent and an antistatic agent that does not react with the release agent. The method of mixing the anthrone-based release agent and the antistatic agent is not particularly limited. Any one of the following methods may be a method in which an antistatic agent is added to an anthrone-based release agent, and a catalyst for curing the release agent is added and mixed; and the anthrone-based release agent is diluted with an organic solvent in advance, and then added. A method of mixing an antistatic agent and a catalyst for curing a release agent; a method of adding and mixing a catalyst, and then adding and mixing an antistatic agent, after diluting the anthrone-based release agent with an organic solvent. In addition, the release agent layer 2 may contain a material such as an adhesion improving agent such as a decane coupling agent, a material having an antistatic effect such as a polyoxyalkylene group-containing compound, or a material such as a cellulose compound, and may be adjusted as needed. Sliding materials, etc.

The release agent layer 2 is formed on the surface of the substrate film 1 by a conventional method. Specifically, a conventional coating method such as gravure coating, Meyer bar coating, or air knife coating can be used.

In the adhesive layer 4 formed on the surface protective film 5 of the present invention, the component of the antistatic agent 3 contained in the release agent layer 2 is not present inside the adhesive layer 4 (outside the surface), and is present only in the adhesive layer. The surface of 4. Thereby, it is possible to suppress the temporal change of the anti-peeling electrostatic performance of the surface protective film 5 and the contamination of the adherend.

The adhesive layer 4 formed on the surface protection film 5 of the present invention is not particularly limited as long as it is adhered to the surface of the adherend, and can be easily peeled off after use, and it is difficult to contaminate the adhesive layer. If considering seeking to bring the invention When the surface protective film 5 is bonded to the film for optics, the acrylic adhesive layer obtained by crosslinking the crosslinked (meth) acrylate copolymer is preferred.

Examples of the (meth) acrylate copolymer include a main monomer such as n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate or isodecyl acrylate, and acrylonitrile, vinyl acetate, and methyl group. A comonomer such as methyl acrylate or ethyl acrylate, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, N-methylol methacrylamide, etc. A copolymer obtained by copolymerization of a functional monomer. The (meth) acrylate copolymer may be a (meth) acrylate as a main monomer and other monomers, or may contain one or two or more monomers other than (meth) acrylate as a main monomer. Monomers other than those.

Further, a compound containing a polyoxyalkylene group may be copolymerized or mixed in the (meth) acrylate copolymer. Examples of the copolymerizable polyoxyalkylene-containing compound include polyethylene glycol (400) monoacrylate, polyethylene glycol (400) monomethacrylate, and methoxy polyethylene glycol (400). Acrylate, methoxypolyethylene glycol (400) methacrylate, polypropylene glycol (400) monoacrylate, polypropylene glycol (400) monomethacrylate, methoxy polypropylene glycol (400) acrylate, A Oxypolypropylene glycol (400) methacrylate or the like. By copolymerizing these polyoxyalkylene-containing monomers with the main monomer and functional monomer of the (meth) acrylate copolymer, a copolymer composed of a polyoxyalkylene group can be obtained. Adhesive.

As the polyoxyalkylene group-containing compound which can be mixed in the (meth) acrylate copolymer, a polyoxyalkylene group-containing (meth) acrylate copolymer is preferred, and a polyoxyalkylene group is contained. Polymerization of (meth)acrylic monomers The compound is more preferable, and examples thereof include polyethylene glycol (400) monoacrylate, polyethylene glycol (400) monomethacrylate, methoxy polyethylene glycol (400) acrylate, and methoxy group. Polyethylene glycol (400) methacrylate, polypropylene glycol (400) monoacrylate, polypropylene glycol (400) monomethacrylate, methoxy polypropylene glycol (400) acrylate, methoxy polypropylene glycol (400 a polymer such as methacrylate. By mixing these polyoxyalkylene-containing compounds with the above (meth) acrylate copolymer, an adhesive to which a polyoxyalkylene-containing compound is added can be obtained.

Examples of the curing agent to be added to the pressure-sensitive adhesive layer 4 include an isocyanate compound, an epoxy compound, a melamine compound, a metal chelate compound, and the like as a crosslinking agent for crosslinking a (meth) acrylate copolymer. Further, examples of the tackifier include rosin, coumarone indene, terpene, petroleum, and phenol.

The thickness of the adhesive layer 4 formed on the surface protection film 5 of the present invention is not particularly limited, and is preferably, for example, about 5 to 40 μm, and more preferably about 10 to 30 μm. The adhesive layer 4 having a peeling strength (adhesion) of the surface protective film to the surface of the adherend of about 0.03 to 0.3 N/25 mm and having a microadhesive force is excellent in workability when the surface protective film is peeled off from the adherend. Preferably.

The method of forming the adhesive layer 4 on the base film 1 of the surface protective film 5 of the present invention is not particularly limited as long as it is carried out by a conventional method. Specifically, a conventional coating method such as reverse coating, comma coating, gravure coating, slot die coating, Meyer bar coating, air knife coating, or the like can be used.

The surface protection film 5 of the present invention having the above structure is The surface potential when the adhesive layer 4 is peeled off from the optical film of the adhesive is preferably +0.7 kV to -0.7 kV. Further, the surface potential is preferably +0.5 kV to -0.5 kV, and the surface potential is particularly preferably +0.2 kV to -0.2 kV. The surface potential can be adjusted by increasing or decreasing the type, amount, and the like of the antistatic agent 3 contained in the release agent layer 2. In consideration of the surface contamination of the optical film as the adherend after peeling off the surface protective film 5 from the optical film as the adherend, the type and amount of the antistatic agent 3 of the release agent layer 2 may be adjusted.

2 is a schematic cross-sectional view showing a state in which the release layer 2 and the adhesive layer 4 are in contact with each other after the surface protection film 5 of the present invention is wound into a roll. A release agent layer containing the antistatic agent 3 and a surface protection film having the adhesive layer 4 containing no antistatic agent 3 formed on the other surface of the base film 1 are formed on one surface of the base film 1. 5, the surface protection film 10 in which the adhesive layer 4 is wound inside in a roll state is formed, whereby the release agent layer 2 and the adhesive layer 4 are in contact with each other in the radial direction of the roll body. Thereby, a part of the antistatic agent (symbol 3) component contained in the release agent layer 2 is transferred to the surface of the adhesive layer 4. FIG. 3 shows a state in which the surface protection film 5 fed from the surface protection film 10 wound in a roll state thus obtained is bonded to the optical member 6. The surface protective film 5 is attached to the surface of the adhesive layer 4 before the component of the antistatic agent 3 is transferred by transferring the component of the antistatic agent 3 from the release agent layer 2 to the surface of the adhesive layer 4. After the adhesive, the peeling static voltage when the surface protective film 5 is peeled off from the adherend is lowered. Further, the peeling static voltage when the surface protective film 5 of Fig. 1 is peeled off from the adherend can be measured by a conventional method. For example, after the surface protective film 5 is bonded to an adherend such as a polarizing plate, the surface protective film 5 is peeled off at a peeling speed of 40 m per minute using a high-speed peeling tester (manufactured by TESTER), and the surface potential is used. The surface potential of the surface of the adherend was measured once every 10 ms, and the maximum value of the absolute value of the surface potential at this time was the peeling static voltage (kV).

In the surface protection film 10 wound in a roll state according to the present invention, the surface protective film 5 restored from the roll-like unwinding is bonded to the surface of the adhesive layer 4 and the antistatic agent 3 is transferred to the surface of the adhesive layer 4 Contacted by the surface of the adhesive. Thereby, the peeling static voltage at the time of peeling off the surface protection film 5 from the adherend can be suppressed low. Further, in the surface protective film 10 wound in a roll state of the present invention, the release agent layer 2 is outside and the adhesive layer 4 is inside, so in the state of the roller, the surface of the adhesive layer 4 is not exposed. And protected. After the surface protective film 5 is retracted from the roll-like unwinding, the release agent layer 2 is integrated with the base film 1, and therefore it is not necessary to remove or discard the release agent layer 2.

Fig. 3 is a cross-sectional view showing an optical member 7 having a surface protective film as an embodiment in which the surface protective film 5 of the present invention is bonded to an optical member. The optical member 7 having the surface protective film is fed from the surface protective film 10 wound in a roll state to the surface protective film 5 of the present invention, and is bonded to the optical member 6 as an adherend via the adhesive layer 4 thereof. obtain. Examples of the optical member 6 include an optical film such as a polarizing plate, a phase difference plate, a screen film, a polarizing plate which also serves as a phase difference plate, and a polarizing plate which also serves as a screen film. Such an optical member can be used as a constituent member of a liquid crystal display device such as a liquid crystal display panel or an optical device such as various measuring instruments. In addition, examples of the optical member include an optical film such as an antireflection film, a hard coat film, and a transparent conductive film for a touch panel.

The surface protection film 5 of the present invention is sent out from the surface protective film 10 wound in a roll state, bonded to an optical member (optical film) as an adherend, and then peeled off from the adherend to remove the surface protective film. At 5 o'clock, it is sufficient The stripping static voltage is suppressed to be low. Therefore, it is not necessary to worry about damaging circuit components such as a driver IC, a TFT element, and a gate line driving circuit, and the production efficiency in the steps of manufacturing a liquid crystal display panel or the like is improved, and the reliability of the production steps can be ensured.

Example

The invention will be described in detail below by way of examples.

(Example 1)

(Preparation of surface protective film)

5 parts by weight of an addition reaction type fluorenone (manufactured by Dow Corning Toray Co., Ltd., trade name: SRX-345), 0.75 parts by weight of Lithium bis(fluorosulfonylimide), toluene and acetic acid 95 parts by weight of a 1:1 mixed solvent of ethyl ester and 0.05 parts by weight of a platinum catalyst (manufactured by Dow Corning Toray Co., Ltd., trade name: SRX-212) were mixed and stirred to prepare a release agent layer of Example 1. coating.

On the other hand, it is composed of a copolymer of 90 parts by weight of 2-ethylhexyl acrylate, 7 parts by weight of methoxypolyethylene glycol (400) methacrylate, and 3 parts by weight of 2-hydroxyethyl acrylate. To 100 parts by weight of a 40% ethyl acetate solution of an adhesive, 2 parts by weight of an isocyanate curing agent (CORONATE (registered trademark) HX) manufactured by TOSOH Co., Ltd. was stirred and mixed to prepare an adhesive composition of Example 1.

On the surface of a polyethylene terephthalate film having a thickness of 38 μm, the coating layer forming the release agent layer of Example 1 was applied with a Meyer bar at a thickness of 0.2 μm after drying, and a hot air of 120 ° C was used. The loop oven was dried for 1 minute to form a release agent layer. Then, on the surface of the polyethylene terephthalate film on which the release agent layer was not formed, the prepared adhesive composition was applied in a thickness of 20 μm after drying, and then subjected to a hot air loop type of 100 ° C. Oven for 2 minutes Dry to form an adhesive layer. Then, the obtained film in which the release agent layer is formed on one surface of the base film and the adhesive layer on the other surface is formed such that the release agent layer and the adhesive layer are in contact with each other with the adhesive layer as the inner side Winding into a roll shape. The obtained adhesive film wound in a roll shape was kept at 40 ° C for 5 days to cure the adhesive layer, and a surface protective film wound in a roll state of Example 1 was obtained.

(Example 2)

A surface protective film wound in a roll state of Example 2 was obtained in the same manner as in Example 1 except that the coating material forming the release agent layer of Example 1 had a thickness of 0.1 μm after drying.

(Example 3)

The addition reaction type fluorenone of Example 1 was changed to Dow Corning Toray Co., Ltd., trade name: SRX-211, and lithium bistrifluoromethanesulfonimide was used instead of lithium difluorosulfonimide. A surface protective film wound in a roll state of Example 3 was obtained in the same manner as in Example 1.

(Comparative Example 1)

A surface protective film wound in a roll state of Comparative Example 1 was obtained in the same manner as in Example 1 except that lithium difluorosulfonimide was not added as an antistatic agent.

(Comparative Example 2)

In addition to adding 0.67 parts by weight of lithium difluorosulfonimide to 100 parts by weight of the 40% ethyl acetate solution on the adhesive side instead of adding lithium difluorosulfonimide to the stripper, In the same manner, a surface protective film wound in a roll state of Comparative Example 2 was obtained.

Hereinafter, the method and result of the evaluation test are shown.

<Method for Measuring Deployment Force of Surface Protective Film>

A sample of the surface protective film which was unwound from the surface protective film wound in a roll state was cut out in a state of being overlapped by two layers, and cut into a width of 50 mm and a length of 150 mm. In a test environment of 23 ° C × 50% RH, the strength at the time of peeling at a peeling speed of 300 mm/min in a direction of 180° was measured by a tensile tester, and this was used as a developing force of the surface protective film (N/50 mm). ).

(surface resistivity of the release agent layer and the adhesive layer)

A high-performance high-resistivity meter (Hiresta (registered trademark)-UP, manufactured by Mitsubishi Chemical Corporation) was used to measure a release agent of a sample of a surface protective film which was retracted by roll-like unwinding under a voltage of 100 V and a measurement time of 30 seconds. The surface resistivity (Ω/□) of the layer and the adhesive layer.

<Method for Measuring Adhesion of Surface Protective Film>

An acrylic film and an anti-glare low-reflection polarizing plate (AG-LR polarizing plate) were bonded to a polarizer (iodine-containing polyvinyl alcohol film) using an ultraviolet curable adhesive as an adherend. The polarizing plate was attached to the surface of the glass plate by a double-sided adhesive tape using a laminating machine. Then, the surface protective film cut into a width of 25 mm was attached to the acrylic film on the surface of the polarizing plate, and then stored in a test environment of 23 ° C × 50% RH for 1 day. Then, the strength at the time of peeling off the surface protection film in the direction of 180° at a peeling speed of 300 mm/min was measured using a tensile tester, and this was used as an adhesive force (N/25 mm).

<Method for Measuring Peeling Static Voltage of Surface Protective Film>

An acrylic film and an anti-glare low-reflection polarizing plate (AG-LR polarizing plate) were bonded to a polarizer (iodine-containing polyvinyl alcohol film) using an ultraviolet curable adhesive as an adherend. Use a laminating machine to pass the double-sided adhesive tape on the glass plate The polarizing plate is attached to the surface. Then, the surface protective film cut into a width of 25 mm was attached to the acrylic film on the surface of the polarizing plate, and then stored in a test environment of 23 ° C × 50% RH for 1 day. Then, the surface protective film was peeled off at a peeling speed of 40 m per minute using a high-speed peeling tester (manufactured by TESTER Co., Ltd.), and the surface potential of the surface of the polarizing plate was measured every 10 ms using a surface potentiometer (manufactured by Keyence Co., Ltd.). The maximum value of the absolute value of the surface potential at the time is the peeling static voltage (kV).

<Method for Confirming Surface Contamination of Surface Protective Film>

An acrylic film and an anti-glare low-reflection polarizing plate (AG-LR polarizing plate) were bonded to a polarizer (iodine-containing polyvinyl alcohol film) using an ultraviolet curable adhesive as an adherend. The polarizing plate was attached to the surface of the glass plate by a double-sided adhesive tape using a laminating machine. Then, a surface protective film cut to a width of 25 mm was attached to the acrylic film on the surface of the polarizing plate, and then stored in a test environment of 23 ° C × 50% RH for 3 days and 30 days. Then, the surface protective film was peeled off to visually observe the presence or absence of contamination on the surface of the polarizing plate, and the surface contamination was confirmed. As a criterion for determining the surface contamination property, the case where no contamination was transferred to the polarizing plate was evaluated as (○), and the case where contamination transfer was confirmed on the polarizing plate was evaluated as (×).

The surface measurement films of the obtained Examples 1 to 3 and Comparative Examples 1 and 2 wound in a roll state were shown in Table 1. "2EHA" means 2-ethylhexyl acrylate, "HEA" means 2-hydroxyethyl acrylate, "#400G" methoxy ethoxylated polyethylene glycol (400) methacrylate, "AS agent (1)" means Lithium difluorosulfonimide, "AS agent (2)" refers to lithium bistrifluoromethanesulfonimide, "SRX-345" refers to SRX-345, "SRX-211" refers to SRX-211, "SRX212" refers to Platinum catalyst SRX-212. Further, "4.2E11" of the surface resistivity means 4.2 × 10 ¹¹ , and "Over-range" means a measurement limit exceeding the measuring machine, and means 1.0 × 10 ¹³ Ω / □ or more.

From the measurement results shown in Table 1, it is known that:

When the surface protective film wound in a roll state in the first to third embodiments of the present invention is used in the form of a roll-like unwinding, it has an appropriate adhesive force and does not contaminate the surface of the adherend. Further, even if the adherend is a polarizing plate using an acrylic film, when the surface protective film is temporarily bonded to the adherend, the peeling static voltage when peeled off from the adherend is low.

On the other hand, in the surface protective film wound in a roll state of Comparative Example 1 in which the antistatic agent was not added to the release agent layer, the surface protective film restored by the roll-like unwinding was temporarily bonded to the adherend, and then Peeling static voltage when peeled off by adhesive Increase. Further, in the case where the release agent layer contains an antistatic agent, the surface protective film of the comparative example 2 in which the pressure-sensitive adhesive layer contains the antistatic agent is wound into a roll state, and the surface protective film restored by the roll-like unwinding is temporarily attached. When it is bonded to the adherend, the peeling static voltage when peeled off from the adherend is low and good, but the contamination of the adherend after peeling off the surface protective film increases.

In other words, in the surface protective film wound in a roll state of Comparative Examples 1 and 2, it was difficult to achieve both a decrease in the peeling static voltage and a low contamination property to the adherend. On the other hand, in the case where an antistatic agent is added to the release agent layer, and the component of the antistatic agent is transferred only on the surface of the adhesive layer, the surface protective film wound in a roll state of Examples 1 to 3 is satisfactorily Both the reduction of the peeling static voltage and the low contamination of the adherend are taken into consideration.

Industrial applicability

The surface protective film of the present invention can be bonded to, for example, a production step of an optical film such as a polarizing plate, a retardation film, a screen film, an antireflection film, a hard coat film, and a transparent conductive film, and various other optical members. The surface of the optical member or the like is used to protect the surface. Further, after the surface protective film of the present invention is bonded to an optical member (optical film) as an adherend, the peeling static voltage generated when the surface protective film is peeled off from the adherend can be suppressed to a low level, and is resistant. The time-dependent change in the peeling static performance and the less pollution to the adherend can be achieved by the yield of the production step and the industrial use value.

1‧‧‧Base film

2‧‧‧ Stripper layer

3‧‧‧Antistatic agent

4‧‧‧Adhesive layer

5‧‧‧Surface protection film

10‧‧‧Surface protection film wound into a roll

Claims (5)

A surface protective film in which a release agent layer is formed on one surface of a base film composed of a resin having transparency, and an adhesive layer is formed on the other surface of the base film, characterized in that the release agent layer An antistatic agent composed of an alkali metal salt and an anthrone-based release agent are contained, and the component of the antistatic agent composed of the alkali metal salt contained in the release agent layer exists only on the surface of the adhesive layer. The surface protective film according to claim 1, wherein the adhesive layer is an acrylic adhesive layer containing a crosslinked (meth) acrylate copolymer. The surface protective film according to claim 1 or 2, wherein the surface potential when the adhesive layer is peeled off from the optical film as the adherend is +0.7 kV to -0.7 kV. The surface protective film according to claim 1 or 2, wherein the base film is wound into a roll shape with the adhesive layer being in contact with the adhesive layer. An optical member obtained by bonding a surface protective film according to any one of claims 1 to 4 to the adhesive layer.