TW201726410A - 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 which can be bonded to an optical film having irregularities on its surface, and an optical member using the protective film, which has less contamination to the adherend and is in the opposite direction. The low contamination of the adhesive does not change over time, and has excellent anti-peeling electrostatic properties that do not deteriorate over time. A surface protective film 10 in which an adhesive layer 2 is formed on one surface of a base film 1 composed of a resin having transparency, and is adhered to a resin via a release agent layer 4 on an adhesive layer 2. The release film 5 of the release agent layer 4 is formed on one surface of the film 3, and the release agent layer 4 contains an alkali metal salt, an ester plasticizer containing at least one ether bond, an anthrone release agent, and a release agent layer 4. The alkali metal salt component contained in it is present only on the surface of the adhesive layer 2.

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, it is possible to provide a surface protective film which is less contaminated by 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, the present invention provides a low-level material even if the constituent material of the polarizing plate as the optical member is changed (the TAC film is changed to an acrylic film or a polyester film, or the aqueous adhesive is changed to an ultraviolet-curable adhesive). A surface protective film that suppresses peeling static voltage generated when the surface protective film is peeled off, and an optical member using the surface protective film.

Further, the optical member in the present invention means 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 protective film of the above 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 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 Propensity. 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 bonded to a surface of an optical film and an optical member using the surface protective film, which 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.

The inventors have conducted intensive studies to solve these problems. In order to reduce contamination of the adherend and to reduce the temporal change of the contamination, it is necessary to reduce the content of the antistatic agent which is presumed to be the cause of the contamination. 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.

Here, the inventors have studied how to suppress the peeling static voltage when the surface protective film is peeled off from the adherend, in a state where the content of the antistatic agent is not increased.

First, the inventors applied an adhesive composition containing no antistatic agent to one surface of a substrate and dried it to prepare a surface protective film in which an adhesive layer was laminated. Thereafter, a release film containing an antistatic agent in the release agent layer is bonded to the surface of the adhesive layer, and the antistatic agent contained in the release agent layer of the release film is transferred onto the surface of the adhesive layer. Thus, it has been found that the peeling static voltage when the surface protective film is peeled off from the adherend can be suppressed to be low, and it is difficult to contaminate the adherend, and the present invention has been completed.

The surface protective film of the present invention is obtained by applying an adhesive composition containing no antistatic agent to one surface of a substrate and drying it to laminate an adhesive layer, and then adhering to the release agent layer on the surface of the adhesive layer. The release film containing an antistatic agent is obtained by transferring an antistatic agent contained in the release agent layer of the release film onto the surface of the adhesive layer. According to the above aspect of the invention, when the surface protective film in which the peeling film has been peeled off is attached to the adherend, the contamination of the adherend is suppressed to be low, and the surface protective film is simultaneously provided. Work from The peeling static voltage at the time of peeling off the film for optical use of the adherend was suppressed to be low.

In order to solve the above problems, the present invention provides a surface protective film. It is characterized in that an adhesive layer is formed on one surface of a base film composed of a resin having transparency, and the adhesive layer is formed on one surface of the resin film via a release agent layer. a surface protective film comprising a release film of the release agent layer, wherein the release agent layer contains an alkali metal salt, an ester plasticizer containing at least one ether bond, and an anthrone release agent, and the release agent layer The alkali metal salt component is present only on the surface of the above adhesive layer.

Further, the above fluorenone-based release agent is preferably a release agent containing polydimethyl siloxane as a main component.

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

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

Further, the peeling force when the release film is peeled off from the pressure-sensitive adhesive layer is preferably 0.005 to 0.3 N/50 mm.

Moreover, the present invention provides an optical member in which the surface protective film is bonded via the adhesive layer in a state where the release film is peeled off.

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

Further, according to the present invention, it is possible to provide a surface protective film and use the same The optical member of the surface protective film, the surface protective film has little contamination to the adherend, and the contamination to the adherend does not change with time.

Further, according to the present invention, it is possible to provide a surface protective film and an optical member using the surface protective film, which is a constituent material of a polarizing plate as an optical member (change of TAC film to acrylic film, cyclic polyolefin) When the film or the polyester film is changed to the ultraviolet curable adhesive, the peeling static voltage at the time of peeling off the surface protective film can be suppressed to be low.

Further, the surface protective film of the present invention is characterized in that an adhesive layer is formed on one surface of a base film composed of a resin having transparency, and is bonded to the adhesive layer via a release agent layer. The release film of the release agent layer is formed on one surface of the resin film, and the component of the alkali metal salt contained in the release agent layer is transferred from the release agent layer to the surface of the adhesive layer to adhere the adhesive layer. The peeling static voltage of the agent layer when peeled off from the adherend is lowered.

Further, according to the surface protection film of the present invention, after the surface protective film in the state in which the release film is peeled off is attached to the adherend, the peeling static voltage when the surface protective film is peeled off from the adherend can be reduced, and Since the peeling static electricity performance changes with time and the contamination to the adherend is small, productivity and productivity can be improved by the optical member as the adherend.

1‧‧‧Base film

2‧‧‧Adhesive layer

3‧‧‧ resin film

4‧‧‧ Stripper layer

5‧‧‧Release film

7‧‧‧Antistatic agent

8‧‧‧Adhesive (optical parts)

10‧‧‧Surface protection film

11‧‧‧Removal of the surface protective film in the state of the peeling film

20‧‧‧Optical parts with surface protection film

1 is a conceptual cross-sectional view showing a surface protective film of the present invention; and FIG. 2 is a cross-sectional view showing a state in which a release film is peeled off from the surface protective film of the present invention; Fig. 3 is a cross-sectional view showing an embodiment in which a surface protective film of the present invention is bonded to an optical member in a state in which a release film is peeled off.

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

Fig. 1 is a conceptual cross-sectional view showing a surface protective film of the invention. The surface protection film 10 is formed with an adhesive layer 2 on the surface of one surface of the transparent base film 1. On the surface of the adhesive layer 2, a release film 5 having a release agent layer 4 formed on the surface of the resin film 3 is bonded.

Further, the release agent layer 4 contains an alkali metal salt, an ester plasticizer containing at least one ether bond, and an anthrone release agent.

As the base film 1 used in the surface protective film 10 of the present invention, a base film composed of a resin having transparency and flexibility is used. Thereby, the appearance of the optical member can be detected in a state in which the surface protective film is bonded to the optical member as the adherend. As the film composed of the transparent resin used as the substrate film 1, polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and poly are preferably used. A polyester film such as butylene terephthalate. In addition to the polyester film, a film composed of another resin may be used as long as it has a desired strength and is optically compatible. 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 or the alignment angle in the axial direction formed by the crystallization of the stretched film may be controlled to a specific value.

The thickness of the base film 1 used in the surface protection film 10 of the present invention is not particularly limited, but is preferably a thickness of about 12 to 100 μm, and more preferably about 20 to 75 μm.

Further, if necessary, an antifouling layer for preventing surface fouling, an antistatic layer, a hard coat layer for preventing scratches, and the like may be provided on the opposite surface of the base film 1 on the side where the adhesive layer 2 is formed. Further, an easy adhesion treatment such as surface modification by a corona discharge or application of an anchoring agent may be performed on the surface of the base film 1.

In the adhesive layer 2 formed in the surface protective film 10 of the present invention, the component of the antistatic agent (alkali metal salt) contained in the release agent layer 4 (described later in detail) does not exist in the adhesive layer. The inside of 2 (external to the surface) exists only on the surface of the adhesive layer 2 (refer to reference numeral 7 in FIGS. 2 and 3). Therefore, it is possible to suppress the temporal change of the anti-peeling electrostatic performance of the surface protective film 10 and the contamination of the adherend.

Further, the adhesive layer 2 formed in the surface protective film 10 of the present invention is not particularly limited as long as it is bonded to the surface of the adherend, can be easily peeled off after use, and is difficult to contaminate the adhesive of the adherend. . The surface protective film 10 of the present invention is preferably an acrylic pressure-sensitive adhesive layer obtained by crosslinking a (meth) acrylate copolymer in consideration of durability and the like after bonding to an optical film.

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 methacrylic acid. Copolymer monomers such as methyl ester and ethyl acrylate, functional monomers such as acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, and N-methylol methacrylamide Copolymerized copolymer. The main monomer of the (meth) acrylate copolymer and other monomers may be (meth) acrylate, and monomers other than the main monomer may contain one or two or more (meth) acrylates. Monomers other than esters.

Further, a compound containing a polyoxyalkylene group may be copolymerized or mixed into the (meth) acrylate copolymer. Examples of the compound containing a copolymerizable polyoxyalkylene group 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 a main monomer or a functional monomer of a (meth) acrylate copolymer, an adhesive composed of a polyoxyalkylene-containing copolymer can be obtained. .

As the polyoxyalkylene group-containing compound which can be mixed with the (meth) acrylate copolymer, a polyoxyalkylene group-containing (meth) propylene copolymer is preferable, and more preferably a polyoxyalkylene group ( a polymer of a methyl) propylene monomer, 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 polymerization A polymer such as propylene glycol (400) methacrylate. By mixing these polyoxyalkylene-containing compounds with a (meth) acrylate copolymer, an adhesive to which a polyoxyalkylene-containing compound is added can be obtained.

Examples of the crosslinking agent to crosslink the (meth) acrylate copolymer as the curing agent to be added to the pressure-sensitive adhesive layer 2 include an isocyanate compound, an epoxy compound, a melamine compound, and a metal chelating compound. Further, examples of the tackifier include rosin, coumarone-oxime, terpenes, and petroleum. Phenolics, etc.

The thickness of the adhesive layer 2 formed in the surface protection film 10 of the present invention is not particularly limited, but is preferably about 5 to 40 μm, more preferably about 10 to 30 μm. Since the operability is excellent when the surface protective film is peeled off from the adherend, the peeling strength (adhesion) of the surface protective film to the surface of the adherend is a microadhesive adhesive layer of about 0.03 to 0.3 N/25 mm. 2 is preferred. In addition, since the workability at the time of peeling off the peeling film 5 from the surface protection film 10 is excellent, the peeling force at the time of peeling the peeling film 5 from the adhesive layer 2 is preferably 0.005 to 0.3 N/50 mm.

Further, the release film 5 used in the surface protection film 10 of the present invention is obtained by laminating a release agent layer 4 on one surface of the resin film 3, and the release agent layer 4 contains an anthrone-based release agent and does not contain the release agent. The antistatic agent 7 to be reacted, and an ester plasticizer containing at least one ether bond in the molecule.

Examples of the resin film 3 include a polyester film, a polyamide film, a polyethylene film, a polypropylene film, and a polyimide film. Since it has excellent transparency and low cost, polyester is particularly preferable. membrane. The resin film may be a non-stretched film or a uniaxial or biaxially stretched film. Further, the stretching ratio of the stretched film and the alignment angle in the axial direction formed by the crystallization of the stretched film can be controlled to specific values.

The thickness of the resin film 3 is not particularly limited, and is, for example, preferably about 12 to 100 μm. If the thickness is about 20 to 50 μm, it is easy to handle, and therefore it is more preferable.

Further, an easy adhesion treatment such as surface modification by a corona discharge or application of an anchoring agent may be performed on the surface of the resin film 3 as needed.

The anthrone-based release agent constituting the release agent layer 4 is preferably a release agent containing polydimethyl siloxane as a main component, and examples thereof include an addition reaction type, a condensation reaction type, a cationic polymerization type, and a radical polymerization type. And other known anthrone release agents. 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 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.). As a commercially available product of the radical polymerization type, there are X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.) and the like.

As the antistatic agent contained in the release agent layer 4, it is preferred that the dispersant solution containing polydimethyl siloxane as a main component has good dispersibility and does not hinder polydimethyl siloxane as a main component. A cured antistatic agent for the release agent of the ingredients. Further, since the surface of the adhesive agent layer 4 is transferred to the surface of the adhesive layer 2 to impart an antistatic effect to the adhesive layer, it is preferable not to react with a release agent containing polydimethyl siloxane as a main component. Alkaline metal salts are very suitable for use as such antistatic agents.

The basic 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 group selected from Cl ^- , Br ^- , I ^- , BF ₄ ^- , PF ₆ ^- , SCN ^- , ClO ₄ ^- , CF ₃ SO _{3 are} suitably used. _{^{-, (CF 3 SO 2)}} 2 N -, (C 2 F 5 SO 2) 2 N -, (CF 3 SO 2) 3 C - anion of the metal salt thereof. Among them, it is particularly preferable to use 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 ( a lithium salt of CF ₃ SO ₂ ) ₃ C or the like. These alkali metal salts may be used singly or in combination of two or more. For stabilization of the ionic substance, a compound containing a polyoxyalkylene structure may be added.

The amount of the antistatic agent added to the release agent containing polydimethyl siloxane as a main component varies depending on the type of the antistatic agent or the affinity between the release agent, but it may be considered to be peeled off from the adherend. The peeling static voltage expected for the surface protective film, the contamination property to the adherend, and the adhesive property are set.

As the plasticizer contained in the release agent layer 4, the release agent solution containing polydimethyl siloxane as a main component has good dispersibility and does not inhibit the peeling of polydimethyl siloxane as a main component. The cured plasticizer of the solution is preferred. Further, the role of the plasticizer is to transfer the antistatic agent contained in the release agent layer 4 from the release agent layer 4 to the surface of the adhesive layer 2. Therefore, the plasticizer is preferably one which does not react with a release agent containing polydimethyl siloxane as a main component. As such a plasticizer, an ester plasticizer containing at least one ether bond in a molecule is suitable.

At least one or more ether linkages present in the molecule in the ester plasticizer need to be easily coordinated to the alkali metal salt. Further, in the surface protective film of the present invention, when the release agent layer is in contact with the adhesive layer, a plasticizer is used in order to efficiently transfer the antistatic agent component from the release agent layer to the surface of the adhesive layer. . In the present invention, in order to improve the affinity of the release agent layer and the adhesive layer, a plasticizer containing an ester group is suitably used.

Examples of the ester plasticizer containing at least one or more ether bonds in the molecule include a dialkylene glycol to a polyalkylene glycol (a glycol having two or more alkylene groups). Ester plasticizer. Specific examples thereof include diethylene glycol di-2-ethylhexanoate, triethylene glycol di-2-ethylhexanoate, and tetraethylene glycol di-2-ethylhexanoate. Hexaethylene glycol di-2-ethylhexanoate, triethylene glycol diethyl butyrate, polyethylene glycol diethyl butyrate, triethylene glycol diacetate, tetraethylene glycol Acid ester, triethylene glycol diheptanoate, tetraethylene glycol diheptanoate, polypropylene glycol diethyl hexanoate, diethylene glycol dibenzoate, triethylene glycol dibenzoate , tetraethylene glycol dibenzoate, polyethylene glycol dibenzoate, dipropylene glycol dibenzoate, polypropylene glycol dibenzoate, or polyethylene glycol-2-ethylhexanoic acid benzene Formate and so on.

As another example, an alkoxyalkyl ester of a carboxylic acid is mentioned. Specific examples thereof include bis(2-butoxyethyl) phthalate, bis(2-butoxyethyl) adipate, and di(butoxyethoxyethyl) adipate. )Wait.

One type of the above ester plasticizers may be used or two or more types may be used in combination. Here, ethylhexanoate is also called ethylhexanoate, ethylhexoate, ethyl hexane acid ester, and the like. Benzoate refers to benzoic acid ester.

The amount of the ester plasticizer added to the release agent containing polydimethyl siloxane as a main component differs depending on the type of the plasticizer and the affinity between the release agent, but it can be considered from the adherend. The peeling static voltage, the staining property to the adherend, the adhesive property, and the like which are desired when the surface protective film is peeled off are set.

The stripper layer 4 is stripped with polydimethyl siloxane as a main component It is composed of a mixture of an antistatic agent and an ester plasticizer which do not react with the release agent. The method of mixing the release agent containing polydimethyl siloxane as a main component with the antistatic agent and the ester plasticizer is not particularly limited. Any of the following methods may be used: a method of adding and mixing an antistatic agent and an ester plasticizer to a release agent containing polydimethyl siloxane as a main component, and adding and mixing a catalyst for curing the release agent; After the solvent is pre-diluted with a release agent containing polydimethyl siloxane as a main component, an antistatic agent, an ester plasticizer, and a catalyst for curing the release agent are added and mixed; polydimethyl methoxy hydride is used as a solvent; A method in which a release agent of a main component is previously diluted in an organic solvent, a catalyst is added and mixed, and an antistatic agent and an ester plasticizer are added and mixed. Further, if necessary, a material having an auxiliary antistatic effect such as a labeling improver such as a decane coupling agent or a compound containing a polyoxyalkylene group may be added.

The mixing ratio (weight ratio) of the release agent containing the polydimethyl siloxane as a main component and the antistatic agent is not particularly limited, but it is resistant to the solid content per 100 parts of the solid component of the release agent which is the main component. The electrostatic agent is preferably in a ratio of about 5 to 100 parts. The amount of the antistatic agent transferred to the surface of the adhesive layer when the amount of the solid content of 100 parts of the solid content of the release agent containing polydimethyl siloxane as a main component is less than 5 parts. It is difficult to exert an antistatic function imparting an adhesive. In addition, when 100 parts of the solid content of the release agent containing polydimethyl siloxane as a main component, when the amount of the solid content of the antistatic agent is more than 100 parts, the antistatic agent and the polydimethyl group are used. The release agent containing the main component of the oxime is simultaneously transferred onto the surface of the adhesive layer, and thus the adhesive property of the adhesive may be lowered.

Strippers and esters with polydimethyl siloxane as main component The mixing ratio (weight ratio) of the plasticizer is not particularly limited, but the solid content of the ester-based plasticizer is preferably 5 based on 100 parts by weight of the solid content of the release agent containing polydimethyl siloxane as a main component. ~300 copies or so. When the solid content of the ester plasticizer is less than 5 parts by weight based on 100 parts of the solid content of the release agent containing polydimethyl siloxane as a main component, the antistatic agent is easily applied to the adhesive. The effect of the surface transfer of the layer makes it difficult to exert an antistatic function imparting an adhesive. In addition, when the solid content of the ester plasticizer is more than 300 parts per 100 parts of the solid content of the release agent containing polydimethyl siloxane as a main component, the peeling performance of the release film may be Getting worse. Further, the antistatic agent and the ester plasticizer are transferred onto the surface of the adhesive layer together with the release agent containing polydimethyl siloxane as a main component, so that the adhesiveness of the adhesive may be lowered.

The method of forming the adhesive layer 2 on the base film 1 of the surface protection film 10 of the present invention and the method of bonding the release film 5 can be carried out by a conventional method, and are not particularly limited. Specifically, the method of (1) coating a resin composition for forming the adhesive layer 2 on one surface of the base film 1 and drying it to form an adhesive layer, and then attaching the release film 5; 2) A method of applying a resin composition for forming the adhesive layer 2 to the surface of the release film 5 and drying it to form an adhesive layer, and then bonding the base film 1 or the like may be used.

Further, a method of forming the adhesive layer 2 on the surface of the substrate film 1 may be a conventional method. Specifically, a conventional coating method such as reverse coating, doctor blade coating, gravure coating, squeezing extrusion coating, Meyer bar coating, or air knife coating can be used.

Further, similarly, the method used when the release agent layer 4 is formed on the resin film 3 may be a conventional method. Specifically, a conventional coating method such as gravure coating, Meyer bar coating, or air knife coating can be used.

In the surface protection film 10 of the present invention having the above-described structure, the surface potential when the adhesive layer 2 is peeled off from the optical film as the adherend is preferably +0.7 kV to -0.7 kV. Further, the surface potential is more preferably +0.5 kV to -0.5 kV, particularly preferably +0.2 kV to -0.2 kV. This surface potential can be adjusted by increasing or decreasing the type, amount, and the like of the antistatic agent 7 and the ester plasticizer contained in the release agent layer 4. The antistatic agent 7 and the ester plasticizer of the release agent layer 4 can be adjusted by considering the surface contamination property of the optical film as the adherend after the surface protective film 10 is peeled off from the optical film as the adherend. The type and amount of addition.

2 is a cross-sectional view showing the surface protective film 11 in a state in which the release film is peeled off, and shows a state in which the release film 5 is peeled off from the surface protection film 10 of the present invention in FIG.

By peeling off the release film 5 from the surface protection film 10 shown in FIG. 1, a part of the antistatic agent (symbol 7) contained in the release agent layer 4 of the release film 5 is transferred (attached) to the surface protective film. 10 of the surface of the adhesive layer 2. Therefore, in the surface protective film 11 from which the release film is peeled off in FIG. 2, the antistatic agent adhering to the surface of the adhesive layer 2 of the surface protective film 11 is represented by a spot (circle) of symbol 7. By transferring the component of the antistatic agent 7 from the release agent layer 4 of the release film 5 to the surface of the adhesive layer 2, the surface of Fig. 2 is compared with the adhesive layer 2 before the component of the antistatic agent 7 is transferred. After the protective film 11 is bonded to the adherend, the peeling static voltage when the surface protective film 11 is peeled off from the adherend is lowered. Further, the peeling static voltage when the surface protective film 11 of FIG. 2 is peeled off from the adherend can pass A conventional method is used for the measurement. For example, after the surface protection film 11 of FIG. 2 is bonded to an adherend such as a polarizing plate, the surface protective film is peeled off at a peeling speed of 40 m per minute using a high-speed peeling tester (manufactured by TESTER Co., Ltd.) while using a surface potentiometer ( The surface potential of the surface of the adherend was measured every 10 ms, and the maximum value of the absolute value of the surface potential at this time was taken as the peeling static voltage (kV).

In the surface protective film of the present invention, when the surface protective film 11 in the state in which the release film is peeled off as shown in Fig. 2 is attached to the adherend, the antistatic agent transferred onto the surface of the adhesive layer 2 is adhered. The surface of the object is in contact. Thereby, the peeling static voltage when the surface protective film 11 is peeled off from the adherend again can be suppressed low.

Further, on the surface of the adhesive layer 2 formed on the surface protective film 10 of the present invention, an ester plasticizer containing at least one or more ether bonds in the molecule may or may not be present. The above-described ester plasticizer may be transferred from the release agent layer 4 of the release film 5 to the surface of the adhesive layer 2, or may not be transferred. When the ester plasticizer is transferred from the release agent layer 4 to the surface of the adhesive layer 2, the ester plasticizer contained in the release agent layer 4 is not present inside the adhesive layer 2 (outside the surface), It is only present on the surface of the adhesive layer 2.

Fig. 3 is a cross-sectional view showing an embodiment in which the surface protective film of the present invention is bonded to the optical member in a state in which the release film is peeled off.

The release film 5 is peeled off from the surface protection film 10 of the present invention to expose the adhesive layer 2 (the surface protection film 11 of FIG. 2), and is bonded to the optical member 8 as an adherend via the adhesive layer 2. .

That is, Fig. 3 shows a method of peeling off from the surface protective film 10 of the present invention. The optical member 20 of the surface protection film 11 in a state where the release film 5 is removed. Examples of the optical member include an optical film such as a polarizing plate, a retardation film, a lens film, a polarizing plate for a phase difference plate, and a polarizing film for a lens film. The optical member can be used as a constituent member such as a liquid crystal display device such as a liquid crystal display or an optical system device of 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.

In the surface protection film 10 of the present invention, the surface protective film 11 in the state in which the release film 5 is peeled off is bonded to the optical member (optical film) as the adherend, and the surface protective film 11 can be sufficiently suppressed from being The peeling static voltage at the time of peeling off the adhesive. Therefore, it is not necessary to worry about damaging the circuit components such as the driver IC, the TFT element, and the gate line driving circuit, and it is possible to improve the production efficiency of the manufacturing steps such as the liquid crystal display and maintain the reliability of the production steps.

Example

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

(Example 1)

(Production of surface protective film)

5 parts by weight of addition reaction type anthrone (manufactured by Dow Corning Toray Co., Ltd., trade name: SRX-345), 0.75 parts by weight of lithium difluorosulfonylimine, and 0.75 parts by weight of tetraethylene glycol di- 2-ethylhexanoate, 95 parts by weight of a 1:1 mixed solvent of toluene and ethyl acetate, and 0.05 part by weight of a platinum catalyst (manufactured by Dow Corning Toray, trade name: SRX-212) were mixed and stirred. The coating forming the release agent layer of Example 1 was prepared by mixing. Formation of Example 1 using Meyer bar coating on the surface of a polyethylene terephthalate resin film having a thickness of 38 μm The coating of the release agent layer was dried to a thickness of 0.2 μm, and dried in a hot air loop oven at 120 ° C for 1 minute to obtain a release film of Example 1.

On the other hand, with respect to 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 100 parts by weight of a 40% ethyl acetate solution of the adhesive was placed, and 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.

The prepared adhesive composition was applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm so as to have a thickness of 20 μm after drying, and then dried in a hot air loop oven at 100 ° C for 2 minutes. Forming an adhesive layer. Thereafter, the release film of Example 1 prepared above was bonded to the surface of the adhesive layer via a release agent layer (an anthrone treatment surface). The obtained adhesive film was kept at 40 ° C for 5 days to cure the adhesive layer, and the surface protective film of Example 1 was obtained.

(Example 2)

The surface protective film of Example 2 was obtained in the same manner as in Example 1 except that the thickness of the release agent layer coating material of Example 1 after drying was 0.1 μm.

(Example 3)

The addition reaction type fluorenone of Example 1 was changed to Dow Corning Toray Co., Ltd., trade name: SRX-211, and lithium bisfluorosulfonyl imide was changed to lithium bistrifluoromethanesulfonimide. Further, the surface protective film of Example 3 was obtained in the same manner as in Example 1.

(Comparative Example 1)

5 parts by weight of addition reaction type anthrone (manufactured by Dow Corning Toray Co., Ltd., trade name: SRX-345), 95 parts by weight of a 1:1 mixed solvent of toluene and ethyl acetate, and 0.05 part by weight of a platinum catalyst ( Dow Corning Toray Co., Ltd., trade name: SRX-212) was stirred and mixed to prepare a coating material which forms the release agent layer of Comparative Example 1. On the surface of a polyethylene terephthalate film having a thickness of 38 μm, the coating material forming the release agent layer of Comparative Example 1 was applied by a Meyer rod so as to have a thickness of 0.2 μm after drying, using 120 ° C. The hot air loop oven was dried for 1 minute to obtain the release film of Comparative Example 1.

On the other hand, the adhesive of Example 1 was applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm so as to have a thickness of 20 μm after drying, and then subjected to a hot air circulation drying oven at 100 ° C. Dry for 2 minutes to form an adhesive layer. Thereafter, the release film of Comparative Example 1 prepared above was bonded to the surface of the adhesive layer via a release agent layer (an anthrone treatment surface). The obtained adhesive film was kept at 40 ° C for 5 days to cure the adhesive layer, thereby obtaining the surface protective film of Comparative Example 1.

(Comparative Example 2)

The surface protective film of Comparative Example 2 was obtained in the same manner as in Example 1 except that tetraethylene glycol di-2-ethylhexanoate was not added to the release agent layer.

(Comparative Example 3)

In addition to adding 0.67 parts by weight of lithium difluorosulfonylimine to 100 parts by weight of a 40% ethyl acetate solution on the adhesive side instead of adding lithium bisfluorosulfonylimide to the stripper, The surface protective film of Comparative Example 3 was obtained in the same manner.

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

<Method for Measuring Peel Force of Release Film>

The sample of the surface protective film was cut into a width of 50 mm and a length of 150 mm. In a test environment of 23 ° C × 50% RH, the strength at the time of peeling off the release film was measured in a direction of 180° at a peeling speed of 300 mm/min using a tensile tester, and this was used as a peeling force of the release film (N/ 50mm).

(surface resistivity of the adhesive layer)

After the release film was peeled off from the surface protective film sample, the adhesive layer was measured under the conditions of an applied voltage of 100 V and a measurement time of 30 seconds using a high-performance high-resistivity meter (Hiresta (registered trademark)-UP manufactured by Mitsubishi Chemical Corporation). Surface resistivity (Ω/□).

<Method for Measuring Adhesion of Surface Protective Film>

A polarizing plate (AG-LR) which is bonded to an acrylic film and subjected to an anti-glare treatment on a polarizing mirror (polyvinyl alcohol film containing iodine element) using an ultraviolet curable adhesive is used as an adherend. The polarizing plate was attached to the surface of the glass plate with a double-sided adhesive tape using a laminator. 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 for one day in a test environment of 23 ° C × 50% RH. Thereafter, the strength at the time of peeling off the surface protective film was measured in a direction of 180° using a tensile tester at a peeling speed of 300 mm/min, and this was taken as a peeling force (N/25 mm).

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

A polarizing plate (AG-LR) which is bonded to an acrylic film and subjected to an anti-glare treatment by using a UV-curable adhesive on a polarizing plate (polyvinyl alcohol film containing iodine element) is used as an adherend. Use a double-sided adhesive tape to apply the bonding machine The diaphragm is attached to the surface of the glass plate. 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 for one day in a test environment of 23 ° C × 50% RH. After that, 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 is taken as the peeling static voltage (kV).

<Method for Determining Surface Contamination of Surface Protective Film>

A polarizing plate (AG-LR) which is bonded to an acrylic film and subjected to an anti-glare treatment by using a UV-curable adhesive on a polarizing plate (polyvinyl alcohol film containing iodine element) is used as an adherend. The polarizing plate was attached to the surface of the glass plate with a double-sided adhesive tape using a laminator. 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. Thereafter, 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 surface contamination. 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 the transition of the contamination on the polarizing plate was confirmed was evaluated as (×).

The measurement results of the obtained surface protective films of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1. "2EHA" is 2-ethylhexyl acrylate, "HEA" is hydroxyethyl acrylate, "#400G" is methoxypolyethylene glycol (400) methacrylate, and "AS agent (1)" is double Lithium fluorosulfonyl imide, "AS agent (2)" is lithium bistrifluoromethanesulfonimide, "SRX-345" is SRX-345, "SRX-211" is SRX-211, "SRX-212" The platinum catalyst SRX-212 and the "plasticizer" are tetraethylene glycol di-2-ethylhexanoate. Further, the "3.2E10" of the surface resistivity is 3.2 × 10 ¹⁰ , and the "over-range" means that the measurement range of the measuring machine is exceeded, that is, 1.0 × 10 ¹³ Ω / □ or more.

According to the measurement results shown in Table 1, the following conclusions can be obtained.

The surface protective films of Examples 1 to 3 of the present invention have a moderate adhesive force and are free from contamination of the surface of the adherend. Further, even if the adherend is a polarizing plate using an acrylic film, the peeling static voltage when the surface protective film is peeled off from the adherend is low.

On the other hand, the surface protective film of Comparative Example 1 in which the antistatic agent was not added to the release agent layer, and the surface protective film of Comparative Example 2 in which the ester plasticizer was not added to the release agent layer, which had a surface protective film The peeling static voltage when peeled off from the adherend increases. In addition, an antistatic agent is used in the adhesive layer instead of the release agent layer. In the surface protective film of Comparative Example 3 in which the antistatic agent was used, the peeling static voltage when the surface protective film was peeled off from the adherend was small, and it was good, but the contamination of the adherend after the peeling was increased.

In other words, in the surface protective films of Comparative Examples 1 to 3, it was difficult to achieve both the reduction of the peeling static voltage and the low contamination of the adherend. On the other hand, in the surface protective films of Examples 1 to 3 in which an antistatic agent and an ester plasticizer were added to the release agent layer, the effect of reducing the peeling static voltage was high, and the adherend was not contaminated, and both of them were lowered in good balance. Peeling static voltage and low contamination of the adherend.

Industrial applicability

The surface protective film of the present invention can be bonded to these in the production steps of an optical film such as a polarizing plate, a retardation film, a lens film, an antireflection film, a hard coat film, and a transparent conductive film, and various other optical members. A surface of an optical component or the like to protect the surface. Further, when the surface protective film of the present invention is bonded to an optical member (optical film) as an adherend in a state in which the release film is peeled off, peeling of the surface protective film from the adherend can be performed. The static voltage suppression is low, and the time-dependent change in the anti-peeling electrostatic property and the contamination to the adherend are small, and the yield of the production step can be improved, and the industrial use value is large.

1‧‧‧Base film

2‧‧‧Adhesive layer

3‧‧‧ resin film

4‧‧‧ Stripper layer

5‧‧‧Release film

7‧‧‧Antistatic agent

10‧‧‧Surface protection film

Claims (6)

A surface protective film in which an adhesive layer is formed on one surface of a base film composed of a resin having transparency, and a surface of the resin film is bonded to the adhesive layer via a release agent layer. The release agent layer is formed by forming a release film of the release agent layer, wherein the release agent layer contains an alkali metal salt, an ester plasticizer containing at least one ether bond, and an anthrone release agent, and the release agent layer The alkali metal salt component contained is present only on the surface of the adhesive layer. The surface protective film according to claim 1, wherein the anthrone-based release agent is a release agent containing polydimethyl siloxane as a main component. The surface protective film according to claim 1 or 2, 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 of the adhesive layer when 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 a peeling force when the release film is peeled off from the adhesive layer is 0.005 to 0.3 N/50 mm. An optical member is obtained by peeling off the peeling film, and bonding the surface protective film according to any one of claims 1 to 5 to the adhesive layer.