TWI699285B - Surface-protective film and optical component attached with the same - 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 protective film and optical component bonded with the surface protective film

The present invention relates to a surface protection film bonded to the surface of an optical component (hereinafter, sometimes referred to as an optical film). In more detail, there is provided a surface protective film and an optical component using the surface protective film. The surface protective film has less pollution to an adherend and does not change over time in the pollution of the adherend. In addition, the present invention provides a way to protect the peeling surface even if the components of the polarizer of the optical component are replaced (the TAC film is changed to an acrylic film or polyester film, and the water-based adhesive is changed to an ultraviolet curable adhesive). A surface protective film in which the peeling static voltage during the film is suppressed low, and an optical component to which the surface protective film is bonded.

In addition, the optical component of the present invention refers to a polarizing plate, a retardation plate, a lens film for a display, and the like.

When manufacturing and transporting optical films such as polarizers, retardation plates, screen films for displays, anti-reflection films, hard coat films, transparent conductive films for touch panels, and optical products such as displays using these optical films , The surface protection film is attached to the surface of the optical film to prevent surface dirt and scratches in the subsequent steps. In order to save the time of peeling off the surface protection film and then attaching it, improve work efficiency, In the state where the surface protection film is bonded to the optical film, the appearance inspection of the optical film as a product is directly performed.

In the manufacturing process of conventional optical products, in order to prevent the adhesion of scars or dirt, a surface protection film having an adhesive layer on one side of the base film is usually used. The surface protection film is bonded to the optical film via a micro-adhesive adhesive layer. The reason for making the adhesive layer micro-adhesive is that when the used surface protection film is peeled and removed from the surface of the optical film, it can be easily peeled off, and the adhesive does not adhere and remain on the product as the adherend. On optical films (the so-called prevention of glue residue).

In recent years, in the production steps of liquid crystal display panels, although the number of occurrences is small, the peeling static voltage generated when the surface protective film bonded to the optical film is peeled and removed, which is used to control the liquid crystal A phenomenon in which circuit components such as a driver IC of the display screen of a display are damaged, or the 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 breakdown voltage of the driving IC is also reduced. Recently, the peeling static voltage is required to be in the range of +0.7kV~-0.7kV.

In addition, a conventional polarizer is a polarizer made of polyvinyl alcohol (PVA) impregnated with iodine, and a triacetyl cellulose film (TAC) is bonded with a water-based adhesive to protect the polarizer. Film) to manufacture polarizers. In recent years, as an alternative to TAC films, polarizers using acrylic films, cyclic polyolefin films, or polyester films have been used, or UV-curable adhesives have been used instead of water-based Adhesive polarizer. The constituent materials used for the polarizer have changed, so the following problems have also occurred: peeling static voltage generated when the surface protective film is peeled off It is higher than when using a polarizer with a traditional structure.

In addition, in recent years, with the spread of 3D displays (stereoscopic displays), FPR (Film Patterned Retarder) films are bonded to the surface of optical films such as polarizers. After peeling the surface protection film bonded on the surface of the optical film, such as a polarizing plate, the FPR film is bonded. However, if the surface of an optical film such as a polarizer is contaminated by the adhesive or antistatic agent used for the surface protective film, there is a problem that the FPR film is difficult to adhere. Therefore, it is required that the surface protective film used for this purpose has little contamination of the adherend.

On the other hand, among several liquid crystal panel manufacturers, as a method for evaluating the contamination of the surface protective film on the adherend, the following method is used: the surface protective film attached to the optical film such as a polarizer is temporarily peeled off, and air bubbles are mixed in. Re-attach and heat-treat under specified conditions in the state, then peel off the surface protective film and observe the surface of the adherend. In this evaluation method, even if the surface contamination of the adherend is slight, there will be a difference in the surface contamination of the adherend between the part where the air bubbles are mixed and the part where the adhesive of the surface protection film is bonded, which is a trace of air bubbles. (Sometimes called bubble spots) and remain. Therefore, as an evaluation method for the contamination of the surface of an adherend, it is a very strict evaluation method. In recent years, there has been a demand for a surface protective film that can be judged as acceptable by the above-mentioned rigorous evaluation method and has very little contamination on the surface of the adherend.

In order to prevent the defect caused by high peeling static voltage generated when the surface protective film is peeled from the adherend after the surface protective film is attached to the optical film as the adherend, a method for applying A surface protective film that uses an adhesive layer containing an antistatic agent with a low peel static voltage.

For example, in Patent Document 1, it is disclosed that a Surface protective film of adhesive composed of trimethylammonium salt, hydroxyl-containing acrylic polymer, and 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 adhesive sheets using the composition.

In addition, Patent Document 3 discloses an adhesive composition composed of an alkali metal salt treated with an acrylic polymer, a polyether polyol compound, and an anion adsorptive compound, and a surface protective film using the composition.

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

Prior art literature

Patent literature

Patent Document 1: Japanese Patent Application Publication No. 2005-131957

Patent Document 2: Japanese Patent Application Publication No. 2005-330464

Patent Document 3: Japanese Patent Application Publication No. 2005-314476

Patent Document 4: Japanese Patent Application Publication No. 2006-152235

In the surface protection films described in Patent Documents 1 to 4, an antistatic agent is added to the inside of the adhesive layer. Therefore, the thicker the thickness of the adhesive layer, or the longer the elapsed time after attaching to the adherend, the antistatic agent will transfer from the adhesive layer to the adherend for the adherend with the surface protective film. Increase in volume Much tendency. In addition, if the amount of the antistatic agent transferred to the adherend increases, the appearance quality of the optical film as the adherend may decrease, and the adhesiveness of the FPR film when the FPR film is bonded may decrease.

In this way, in order to reduce the time-dependent change in the transfer of the antistatic agent from the adhesive layer to the adherend, if the thickness of the adhesive layer is reduced, other problems occur. For example, there is a problem that when using a polarizer that has been anti-glare treated to prevent glare on an optical film with irregularities on the surface, it is difficult for the adhesive layer to follow the irregularities on the surface of the optical film and mix in bubbles; As the bonding area between the optical film and the adhesive layer decreases, the adhesive force decreases, and the surface protective film floats or peels off during use.

In addition, in order to reduce the time-dependent change of the antistatic agent from the adhesive layer to the adherend, if the amount of the antistatic agent added to the adhesive layer is reduced, the surface protective film will be peeled off and removed from the adherend. The peeling static voltage increases, and there is a risk of causing damage to circuit components such as driver ICs, or damage to the alignment of liquid crystal molecules.

The present invention has been completed in view of the above circumstances, and its technical subject is to provide a surface protective film bonded to the surface of an optical film and an optical component using the surface protective film. The surface protective film has an optical surface with unevenness. The film can also be attached, the pollution to the adherend is very small, and the low pollution of the adherend does not change with time.

In addition, the technical problem of the present invention is to provide a method that even if the component parts of the polarizer as an optical component are replaced (the TAC film is changed to an acrylic film or polyester film, and the water-based adhesive is changed to an ultraviolet curable adhesive), A surface protective film that can suppress the peeling static voltage when peeling the surface protective film to a low level, and make Optical parts using this surface protective film.

In order to solve the above-mentioned technical problems, the inventor conducted careful research. In order to reduce the contamination of the adherend and reduce the change over time in the pollution, it is necessary to reduce the content of the antistatic agent that is presumed to be the cause of the contamination of the adherend. However, when the content of the antistatic agent is reduced, the peeling static voltage when the surface protection film is peeled from the adherend increases.

Therefore, the inventors studied a method for suppressing the peeling static voltage when the surface protective film is peeled from the adherend to a low level without increasing the content of the antistatic agent.

The inventor first applied an adhesive composition containing no antistatic agent to one side of the substrate and dried, layered an adhesive layer, and layered a release agent layer containing an antistatic agent on the other side of the substrate to produce a surface protection membrane. Then, the surface protection film is wound into a roll so that the adhesive layer is inside, whereby the components of the antistatic agent contained in the release agent layer are transferred to the surface of the adhesive layer to form The state only exists on the surface of the adhesive layer. It was found that after temporarily bonding the surface protective film to the optical film as the adherend, the peeling static voltage during peeling from the adherend was suppressed to be low, and it was difficult to contaminate the adherend, thereby completing the present invention.

In the surface protective film of the present invention, an adhesive composition containing no antistatic agent is applied to one side of a substrate and dried, an adhesive layer is laminated, and a release agent layer containing an antistatic agent is laminated on the other side of the substrate After that, the surface protection film is wound into a roll shape so that the adhesive layer is inside, thereby transferring the component of the antistatic agent contained in the release agent layer on the surface of the adhesive layer. Inventive structure of the present invention The idea is that when the surface protective film wound in a roll shape is rolled out from the roll shape, and bonded to the adherend, the contamination of the adherend is suppressed to be low, and the surface The peeling static voltage when the protective film is peeled from the optical film as an adherend is suppressed to be low.

In order to solve the above technical problems, the present invention provides a surface protective film characterized by forming a release agent layer on one surface of a base film made of a resin having transparency, and forming a release agent layer on the other An adhesive layer is formed on the surface, and the release agent layer contains an antistatic agent composed of an alkali metal salt and a silicone release agent, and only the components of the antistatic agent composed of an alkali metal salt contained in the release agent layer are present On the surface of the adhesive layer.

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

In addition, the surface potential when peeling off the adhesive layer from the optical film as the adherend is preferably +0.7 kV to -0.7 kV.

In addition, the base film is preferably wound in a roll shape with the adhesive layer as the inner side in such a manner that the release agent layer is in contact with the adhesive layer.

In addition, the present invention provides an optical component, which is formed by bonding the surface protective film via the adhesive layer.

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

In addition, according to the present invention, it is possible to provide a surface protection film that has very little contamination to an adherend and does not change over time in the contamination of the adherend, and an optical component using the surface protection film.

Furthermore, according to the present invention, it is possible to provide a component of the polarizing plate of an optical component (change from TAC film to acrylic film, cyclic polyolefin film or polyester film, change from water-based adhesive to ultraviolet curable adhesive). Adhesive), a surface protective film that can also suppress the peeling static voltage when the surface protective film is peeled off to a low level, and provides an optical component using the surface protective film.

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

That is, the present invention has the following characteristics: after the surface protective film is unrolled and restored from the surface protective film wound in a roll shape is attached to the adherend, the peeling static voltage when the surface protective film is peeled from the adherend is reduced, and the resistance The time-dependent change of the peeling electrostatic performance and the less contamination of the adherend can be expected to improve the productivity and yield of the optical component as the adherend.

1‧‧‧Base film

2‧‧‧Release agent layer

3‧‧‧Antistatic agent

4‧‧‧Adhesive layer

5‧‧‧Surface protection film

6‧‧‧Optical components (optical film)

7‧‧‧Optical components with surface protective film

10‧‧‧Surface protection film wound into a roll

1 is a schematic cross-sectional view showing the surface protection film of the present invention wound in a roll shape; FIG. 2 is a view showing the state where the release agent layer and the adhesive layer are in contact with the surface protection film of the present invention in a roll shape state Figure 3 is a cross-sectional view of an embodiment in which the surface protection film of the present invention is attached to an optical component.

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

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

The surface protection film 5 has a release agent layer 2 containing an antistatic agent 3 composed of an alkali metal salt on one side of a transparent base film 1, and an adhesive layer 2 is formed on the other side of the base film 1.剂层4。 Agent layer 4. A surface protective film 5 with a release agent layer 2 on one side of the base film 1 and an adhesive layer 4 on the other side of the base film 1 is connected with the release agent layer 2 and the adhesive layer 4 In this way, the adhesive layer 4 is wound into a roll shape on the inside, thereby obtaining a surface protective film 10 wound into a roll shape, and the components of the antistatic agent 3 contained in the release agent layer 2 are transferred To the surface of the adhesive layer 4, only the surface of the adhesive layer 4 exists.

As the base film 1 used for the surface protection film 5 of the present invention, a base film made of a resin having transparency and flexibility can be used. Thereby, in a state where the surface protection film 5 is bonded to the optical component as an adherend, the appearance inspection of the optical component can be performed. A film composed of a transparent resin used as the base film 1 can suitably use polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, Polybutylene terephthalate and other polyester films. In addition to polyester films, films made of other resins can also be used as long as they have the required strength and optical compatibility. The base film 1 may be a non-stretched film, or a uniaxially or biaxially stretched film. In addition, the stretching magnification 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 used for the surface protection film 5 of the present invention is not particularly limited. For example, a thickness of about 12-100 μm is preferred, and a thickness of about 20-75 μm is more convenient for handling.

In addition, an easy adhesion treatment such as surface modification by corona discharge and application of an anchoring agent may be applied to the surface of the base film 1 as needed.

In addition, the release agent layer 2 formed on the surface protective 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, a silicone release agent is suitably used.

Examples of the silicone release agent include conventional silicone release agents such as addition reaction type, condensation reaction type, cationic polymerization type, and radical polymerization type. Among the products marketed as addition reaction type silicone-based release agents, for example, KS-776A, KS-847T, KS-779H, KS-837, KS-778, KS-830 (Shin-Etsu Chemical Co., Ltd. ) System), SRX-211, SRX-345, SRX-357, SD7333, SD7220, SD7223, LTC-300B, LTC-350G, LTC-310 (Dow Corning Toray (stock) system), etc. Among the products marketed as a condensation reaction type, for example, SRX-290, SYLOFF-23 (manufactured by Dow Corning Toray Co., Ltd.) and the like can be cited. Examples of products commercially available as cationic polymerization type include TPR-6501, TPR-6500, UV9300, VU9315, UV9430 (manufactured by Momentive Performance Materials), X62-7622 (manufactured by Shin-Etsu Chemical Co., Ltd.), and the like. Among the products marketed as a radical polymerization type, for example, X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.) and the like can be cited.

The antistatic agent 3 contained in the release agent layer 2 has good dispersibility to the silicone-based release agent solution and does not hinder the curing of the silicone-based release agent. Electrostatic agent is better. In addition, on the surface of the adhesive layer 4 in contact with the release agent layer 2, the components of the antistatic agent 3 contained in the release agent layer 2 are transferred to impart an antistatic function to the surface of the adhesive layer 4, so it is not Antistatic agents that react with silicone release agents are preferred. As such an antistatic agent, an alkali metal salt is suitable.

Examples of alkali metal salts include metal salts composed of lithium, sodium, and potassium. Specifically, for example, be applied by the selected Li ^+, Na ^+, K ⁺ is a cation selected from ^{Cl -, Br -, I -} , BF 4 -, PF 6 -, SCN -, ClO 4 -, CF 3 SO _{^{3 -, (CF 3 SO 2}} ) 2 N -, (C 2 F 5 SO 2) 2 N -, (CF 3 SO 2) 3 C - anions of the metal salt. 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 ₂ ) ₂ ) Lithium salts such as ₃ C are preferred. These alkali metal salts may be used alone or in combination of two or more kinds. In order to stabilize the ionic substance, a compound containing a polyoxyalkylene structure may be added.

The amount of antistatic agent added to the silicone-based release agent varies depending on the type of antistatic agent or the degree of affinity with the silicone-based release agent, but the desired peeling when peeling the surface protective film from the adherend can be considered Set the static voltage, the pollution of the adherend, and the adhesion characteristics. The mixing ratio (weight ratio) of the silicone-based release agent and the antistatic agent is, for example, a ratio of 5-100 based on the solid content of the silicone-based release agent. Preferably, the ratio is 5-60. If the solid content of the antistatic agent is less than 5 relative to the solid content of 100 of the silicone-based release agent, the transfer amount of the antistatic agent to the surface of the adhesive layer will decrease, making it difficult to perform in the adhesive. Antistatic function. In addition, if the solid content of the antistatic agent is more than 100 relative to the 100 solid content of the silicone release agent, the silicone release The components of the agent and the antistatic agent are simultaneously transferred to the surface of the adhesive layer, so there is a possibility of reducing the adhesive properties of the adhesive.

The release agent layer 2 is composed of at least a silicone-based release agent and an antistatic agent that does not react with the release agent. The method of mixing the silicone release agent and the antistatic agent is not particularly limited. Any of the following methods can be used: add antistatic agent to the silicone release agent, after mixing, add and mix the catalyst for curing of the release agent; dilute the silicone release agent with an organic solvent in advance, and then add , The method of mixing the antistatic agent and the catalyst for curing of the release agent; the method of adding and mixing the catalyst after diluting the silicone release agent with an organic solvent in advance, and then adding and mixing the antistatic agent, etc. In addition, the release agent layer 2 may contain adhesion improvers such as silane coupling agents, materials that assist antistatic effects such as polyoxyalkylene-containing compounds, materials that impart printing properties such as cellulose compounds, and adjustments as needed. Sliding materials, etc.

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

In the adhesive layer 4 formed on the surface protective film 5 of the present invention, the components of the antistatic agent 3 contained in the release agent layer 2 do not exist inside the adhesive layer 4 (outside the surface), but only exist in the adhesive layer 4 surface. Thereby, the time-dependent change of the anti-peeling static electricity performance of the surface protective film 5 and the contamination of an adherend can be suppressed.

The adhesive layer 4 formed on the surface protective film 5 of the present invention is not particularly limited, as long as it is an adhesive layer that adheres to the surface of an adherend, can be easily peeled off after use, and is difficult to contaminate the adherend. If you consider seeking to combine the invention For durability and the like after bonding the surface protection film 5 to the optical film, an acrylic adhesive layer formed by crosslinking a crosslinked (meth)acrylate copolymer is preferable.

Examples of (meth)acrylate copolymers include main monomers such as n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, and isononyl acrylate, and acrylonitrile, vinyl acetate, methyl Comonomers such as methyl acrylate and ethyl acrylate, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, N-methylol methacrylamide, etc. A copolymer of functional monomers. The (meth)acrylate copolymer can be that the main monomer and other monomers are both (meth)acrylates, or it can contain one or more of monomers other than (meth)acrylates as the main monomer Other monomers.

In addition, a (meth)acrylate copolymer may be copolymerized or mixed with a polyoxyalkylene group-containing compound. The copolymerizable polyoxyalkylene-containing compound includes 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, methoxypolypropylene glycol (400) acrylate, methacrylate Oxypropylene glycol (400) methacrylate and the like. By copolymerizing these polyoxyalkylene-containing monomers with the main monomer and functional monomer of the (meth)acrylate copolymer, it is possible to obtain a polyoxyalkylene-containing copolymer composed of The adhesive.

As the polyoxyalkylene-containing compound that can be mixed in the (meth)acrylate copolymer, the polyoxyalkylene-containing (meth)acrylate copolymer is preferred, and the polyoxyalkylene-containing compound is preferred. (Meth) acrylic monomer polymerization The compound is more preferable, for example, polyethylene glycol (400) monoacrylate, polyethylene glycol (400) monomethacrylate, methoxy polyethylene glycol (400) acrylate, methoxy Polyethylene glycol (400) methacrylate, polypropylene glycol (400) monoacrylate, polypropylene glycol (400) monomethacrylate, methoxy polypropylene glycol (400) acrylate, methoxy polypropylene glycol (400) ) Polymers such as methacrylate. By mixing these polyoxyalkylene-containing compounds with the above-mentioned (meth)acrylate copolymer, it is possible to obtain an adhesive to which the polyoxyalkylene-containing compound is added.

As a curing agent added to the adhesive layer 4, an isocyanate compound, an epoxy compound, a melamine compound, a metal chelate compound, etc. are mentioned as a crosslinking agent which crosslinks a (meth)acrylate copolymer. Moreover, as a thickener, rosin, coumarone indene, terpene, petroleum, phenol, etc. are mentioned.

The thickness of the adhesive layer 4 formed on the surface protection film 5 of the present invention is not particularly limited. For example, a thickness of about 5-40 μm is preferable, and a thickness of about 10-30 μm is more preferable. The peel strength (adhesive force) of the surface protective film to the surface of the adherend is about 0.03~0.3N/25mm, and the adhesive layer 4 with micro-adhesive force is excellent due to the excellent workability when peeling the surface protective film from the adherend. Better.

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 performed by a conventional method. Specifically, conventional coating methods such as reverse coating, comma coating, gravure coating, slot die coating, Meyer bar coating, and air knife coating can be used.

The surface protective film 5 of the present invention having the above-mentioned structure is The surface potential when the adhesive layer 4 is peeled from the optical film of the adhesive is preferably +0.7 kV to -0.7 kV. Furthermore, the surface potential is more preferably +0.5kV~-0.5kV, and the surface potential is particularly preferably +0.2kV~-0.2kV. The surface potential can be adjusted by increasing or decreasing the type and amount of the antistatic agent 3 contained in the release agent layer 2. After peeling the surface protective film 5 from the optical film as the adherend, the surface contamination of the optical film as the adherend can be considered, and 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 agent layer 2 and the adhesive layer 4 are in contact with each other in a state where the surface protection film 5 of the present invention is wound into a roll shape. A surface protective film having a release agent layer 2 containing an antistatic agent 3 formed on one side of the base film 1 and an adhesive layer 4 containing no antistatic agent 3 is formed on the other side of the base film 1. 5. The surface protection film 10 wound in a roll shape with the adhesive layer 4 as the inside 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. As a result, 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 protective film 5 sent out from the surface protective film 10 wound in a roll shape obtained in this manner is bonded to the optical component 6. Compared with the adhesive layer 4 before the components of the antistatic agent 3 are transferred by transferring the components of the antistatic agent 3 from the release agent layer 2 to the surface of the adhesive layer 4, the surface protective film 5 is attached to the surface of the adhesive layer 4. After the adherend, the peeling static voltage when peeling off the surface protective film 5 from the adherend decreases. In addition, the peeling static voltage when peeling the surface protective film 5 of FIG. 1 from the adherend can be measured by a conventional method. For example, after bonding the surface protective film 5 to an adherend such as a polarizer, use a high-speed peel tester (manufactured by TESTER Sangyo) to peel the surface protective film 5 at a peeling speed of 40m per minute while using the surface potential A meter (manufactured by Keyence) measures the surface potential of the surface of the adherend every 10 ms, and the maximum absolute value of the surface potential at this time is the peeling static voltage (kV).

In the surface protection film 10 wound in a roll shape of the present invention, when the surface protection film 5 recovered from the roll shape is bonded to the adherend, the antistatic agent 3 and the antistatic agent 3 transferred to the surface of the adhesive layer 4 The surface of the adherend is in contact. Thereby, the peeling static voltage when the surface protective film 5 is peeled from the adherend can be suppressed to be low again. In addition, in the surface protection film 10 wound in a roll state of the present invention, the release agent layer 2 is the outside and the adhesive layer 4 is the inside. Therefore, in the roll state, the surface of the adhesive layer 4 is not exposed And be protected. After the surface protection film 5 is restored from the roll-shaped unwinding, the release agent layer 2 is integrated with the base film 1, so there is no need to remove or discard the release agent layer 2.

Fig. 3 is a cross-sectional view showing an optical component 7 with a surface protection film as an example in which the surface protection film 5 of the present invention is bonded to an optical component. The optical component 7 with a surface protection film is the surface protection film 5 of the present invention that is sent out from the surface protection film 10 wound in a roll shape, and is bonded to the optical component 6 as the adherend via the adhesive layer 4 obtain. Examples of the optical component 6 include optical films such as a polarizing plate, a retardation plate, a screen film, a polarizing plate that also serves as a retardation plate, and a polarizing plate that also serves as a screen film. Such optical components can be used as constituent components of liquid crystal display devices such as liquid crystal display panels, optical devices of various measuring instruments, and the like. Moreover, as an optical component, the optical film, such as an antireflection film, a hard coat film, and a transparent conductive film for touch panels, can also be mentioned.

The surface protective film 5 of the present invention is sent out from the surface protective film 10 wound in a roll shape, and is bonded to an optical component (optical film) as an adherend, and then the surface protective film is peeled off from the adherend 5 o'clock, can fully Ground suppresses the peeling static voltage low. Therefore, there is no need to worry about damaging circuit components such as driver ICs, TFT elements, gate line driver circuits, etc., and the production efficiency in the steps of manufacturing liquid crystal display panels is improved, and the reliability of the production steps can be guaranteed.

Example

The following examples illustrate the present invention in detail.

(Example 1)

(Preparation of surface protective film)

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

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

On the surface of a polyethylene terephthalate film with a thickness of 38 μm, the paint that forms the release agent layer of Example 1 was coated with a Meyer bar to a thickness of 0.2 μm after drying, and heated at 120°C. The loop oven was dried for 1 minute to form a release agent layer. Then, on the surface of the polyethylene terephthalate film where the release agent layer was not formed, the prepared adhesive composition was coated so that the thickness after drying was 20 μm, and then it was looped with hot air at 100°C. Oven for 2 minutes Dry to form an adhesive layer. Then, the obtained film with a release agent layer formed on one surface of the base film and an adhesive layer formed on the other surface is such that the release agent layer is in contact with the adhesive layer, with the adhesive layer as the inner side Wind up into a roll. The obtained adhesive film wound in a roll shape was kept at a temperature of 40° C. for 5 days to cure the adhesive layer to obtain a surface protection film wound in a roll state of Example 1.

(Example 2)

In the same manner as in Example 1, except that the thickness of the paint forming the release agent layer of Example 1 after drying was 0.1 μm, the surface protective film of Example 2 in a roll-like state was obtained.

(Example 3)

Except that the addition reaction type silicone of Example 1 was changed to Dow Corning Toray Co., Ltd. product, trade name: SRX-211, and lithium bistrifluoromethanesulfonamide was used instead of lithium bisfluorosulfonamide In the same manner as in Example 1, the surface protection film of Example 3 wound in a roll state was obtained.

(Comparative example 1)

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

(Comparative example 2)

In addition to adding 0.67 parts by weight of lithium bisfluorosulfonamide to 100 parts by weight of the 40% ethyl acetate solution on the adhesive side, instead of adding lithium bisfluorosulfonamide to the release agent, the same as the examples In the same manner as 1, the surface protective film of Comparative Example 2 wound in a roll state was obtained.

The method and results of the evaluation test are shown below.

<Measurement method of spreading force of surface protective film>

A sample of the surface protection film unwound and restored from the surface protection film wound in a roll state was cut out in a state where the two layers were overlapped, and cut to a width of 50 mm and a length of 150 mm. Under the test environment of 23℃×50%RH, the tensile testing machine was used to measure the strength when peeling in the direction of 180° at a peeling speed of 300mm/min, and this was used as the spreading force of the surface protective film (N/50mm ).

(Surface resistivity of release agent layer and adhesive layer)

Using a high-performance high-resistivity meter (Hiresta (registered trademark)-UP manufactured by Mitsubishi Chemical Analytech Co., Ltd.), under the conditions of an applied voltage of 100V and a measurement time of 30 seconds, the release agent of the sample of the surface protective film recovered from the roll-shaped unwinding was measured Surface resistivity of layer and adhesive layer (Ω/□).

<Measurement method of adhesion of surface protective film>

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

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

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

<How to confirm the surface contamination of the surface protective film>

The polarizer (a polyvinyl alcohol film containing iodine) is bonded with an acrylic film and anti-glare and low-reflection treated polarizer (AG-LR polarizer) using an ultraviolet curable adhesive as the adherend. Using a laminating machine, the polarizing plate was bonded on the surface of the glass plate with a double-sided adhesive tape. Then, a surface protection film cut to a width of 25 mm was bonded to the acrylic film on the surface of the polarizer, 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, and the presence or absence of contamination on the surface of the polarizing plate was visually observed to confirm the surface contamination. As a criterion for determining surface contamination, the case where there is no contamination transfer on the polarizing plate was evaluated as (○), and the case where contamination transfer was confirmed on the polarizing plate was evaluated as (×).

For the obtained surface protection films of Examples 1 to 3 and Comparative Examples 1 and 2 wound in a roll state, the measurement results of the measurement are shown in Table 1. "2EHA" refers to 2-ethylhexyl acrylate, "HEA" refers to 2-hydroxyethyl acrylate, "# 400G" methoxy polyethylene glycol (400) methacrylate, and "AS agent (1)" refers to Lithium bisfluorosulfonamide, "AS agent (2)" refers to lithium bistrifluoromethanesulfonamide, "SRX-345" refers to SRX-345, "SRX-211" refers to SRX-211, and "SRX212" refers to Platinum catalyst SRX-212. In addition, the surface resistivity "4.2E11" refers to 4.2×10 ¹¹ , and “over-range” refers to exceeding the measurement limit of the measuring machine, which means 1.0×10 ¹³ Ω/□ or more.

It can be seen from the measurement results shown in Table 1:

The surface protection films wound in a roll-like state of Examples 1 to 3 of the present invention have a moderate adhesive force when used after being restored from a roll-like unwinding and do not pollute the surface of the adherend. In addition, even if the adherend is a polarizing plate using an acrylic film, after temporarily bonding the surface protective film to the adherend, the peeling static voltage when peeling from the adherend is low.

On the other hand, for the surface protective film of Comparative Example 1 in which no antistatic agent was added to the release agent layer, the surface protective film wound in a roll-like state was temporarily bonded to the adherend after unwinding the roll. Peeling static voltage when the adherend is peeled off Increase. In addition, as an alternative to making the release agent layer contain an antistatic agent, the surface protection film of Comparative Example 2 in which the adhesive layer contains an antistatic agent is wound into a roll state, which temporarily pastes the surface protection film recovered from the roll shape After being combined with an adherend, the peeling static voltage when peeling from the adherend is low and good, but the contamination of the adherend after peeling off the surface protective film increases.

That is, it is difficult for the surface protection films of Comparative Examples 1 to 2 wound in a roll-like state to achieve both a reduction in the peeling static voltage and low contamination of the adherend. On the other hand, the surface protection films of Examples 1 to 3 in which an antistatic agent is added to the release agent layer and only the components of the antistatic agent are transferred to the surface of the adhesive layer are wound in a roll state. It takes into account the reduction of peeling static voltage and the low pollution to the adherend.

Industrial applicability

The surface protection film of the present invention can be bonded to, for example, polarizers, retardation plates, screen films, antireflection films, hard coat films, transparent conductive films, and other optical films and other various optical components in the production process. The surface of the optical component is used to protect the surface. In addition, after the surface protection film of the present invention is bonded to an optical component (optical film) as an adherend, the peeling static voltage generated when the surface protection film is peeled from the adherend can be suppressed to a low level and is resistant to The time-dependent change of the peeling electrostatic performance and the less pollution to the adherend, the yield rate through the production steps, the industrial use value is great.

1‧‧‧Base film

2‧‧‧Release agent layer

3‧‧‧Antistatic agent

4‧‧‧Adhesive layer

5‧‧‧Surface protection film

10‧‧‧Surface protection film wound into a roll

Claims (4)

A surface protective film in which a release agent layer is formed on one side of a base film made of a resin having transparency, and an adhesive layer is formed on the other side of the base film, characterized in that the release agent layer Containing an antistatic agent composed of an alkali metal salt and a silicone release agent, the base film is wound into a roll shape with the adhesive layer as the inner side in such a manner that the release agent layer and the adhesive layer are in contact with each other. The component of the antistatic agent composed of the alkali metal salt contained in the release agent layer is transferred to the surface of the adhesive layer and exists only on the surface. The surface protection film described in the first item of the patent application, wherein the adhesive layer is an acrylic adhesive layer containing a crosslinked (meth)acrylate copolymer, which is relative to the solid content of the silicone-based release agent 100 parts by weight, the release agent layer contains 5-60 parts by weight of the solid content of the antistatic agent. The surface protection film described in item 1 or 2 of the scope of patent application, wherein the surface potential when the adhesive layer is peeled from the optical film as the adherend is +0.7kV~-0.7kV. An optical component, which is formed by bonding the surface protective film as described in any one of items 1 to 3 in the scope of patent application via the adhesive layer.

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