JP2019014257A - Release film for antistatic surface protective film - Google Patents

Abstract

To provide a release film for an antistatic surface protective film, which can be used even for an optical film having a concavo-convex pattern on its surface, gives little contamination to an adherend, maintains low contamination property with respect to an adherend even for a long period of time, and has excellent peeling antistatic performance while preventing degradation with time.SOLUTION: A release film 5 for an antistatic surface protective film is prepared by depositing a release agent layer 4 on one surface of a resin film 3, the release agent layer comprising a release agent essentially comprising dimethyl polysiloxane, an antistatic agent that does not react with the release agent, and an ester-based plasticizer containing at least one ether bond, in which the antistatic agent contains, as a component, an ionic compound having a melting point of less than 30°C. When the release film 5 is laminated on an antistatic surface protective film having an adhesive layer 2 formed on one surface of a base film 1 made of a transparent resin, with the release agent layer 4 in contact with the surface of the adhesive layer 2 of the protective film, the antistatic agent and the ester-based plasticizer in the release agent layer 4 can be transferred to the surface of the adhesive layer 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a surface protective film that is bonded to the surface of an optical component (hereinafter also referred to as an optical film) such as a polarizing plate, a retardation plate, and a lens film for display. More specifically, the present invention provides a surface protective film with little contamination to an adherend, a surface protective film having excellent peeling antistatic performance without deterioration over time, and an optical component using the same.

  Conventionally, optical films such as polarizing plates, retardation plates, lens films for displays, antireflection films, hard coat films, transparent conductive films for touch panels, and optical products such as displays using the films are manufactured. When transporting, a surface protective film is bonded to the surface of the optical film to prevent the surface from being soiled or scratched in the subsequent step. The appearance inspection of the optical film, which is a product, may be performed while the surface protective film is bonded to the optical film in order to remove the trouble of bonding the surface protective film and increase the work efficiency again.

  In general, a surface protective film having a pressure-sensitive adhesive layer provided on one side of a base film is used to prevent adhesion of scratches and dirt in an optical product manufacturing process. The surface protective film is bonded to the optical film via a pressure-sensitive adhesive layer. The adhesive layer has a slight adhesive force because it can be easily removed when the used surface protection film is removed from the surface of the optical film and the adhesive is an adherend. This is to prevent the adhesive film from adhering and remaining on the optical film (preventing the occurrence of so-called adhesive residue).

In recent years, in the production process of a liquid crystal display panel, for controlling the display screen of the liquid crystal display panel by the peeling voltage generated when the surface protective film bonded on the optical film is peeled off and removed, A phenomenon in which circuit components such as driver ICs are destroyed and a phenomenon in which the orientation of liquid crystal molecules is damaged occur although the number of occurrences is small.
In addition, in order to reduce the power consumption of the liquid crystal display panel, the driving voltage of the liquid crystal material has been lowered, and accordingly, the breakdown voltage of the driver IC has also been lowered. Recently, it has been required to set the peeling band voltage within the range of +0.7 kV to -0.7 kV.

  In recent years, with the widespread use of 3D displays (stereoscopic displays), there are films in which an FPR (Film Patterned Retarder) film is bonded to the surface of an optical film such as a polarizing plate. After peeling off the surface protective film bonded to 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 polarizing plate is contaminated with the pressure-sensitive adhesive or antistatic agent used in the surface protective film, there is a problem that the FPR film is difficult to adhere. For this reason, the surface protection film used for the said use is a thing with little contamination with respect to a to-be-adhered body.

  Also, in some liquid crystal panel manufacturers, as a method for evaluating the contamination of the adherend of the surface protective film, the surface protective film bonded to the optical film such as a polarizing plate is peeled off once and air bubbles are mixed in. In this state, a method is employed in which the re-bonded material is heat-treated under predetermined conditions, and then the surface protective film is peeled off to observe the surface of the adherend. In such an evaluation method, even if the surface contamination of the adherend is very small, the difference in surface contamination of the adherend between the portion where the bubbles are mixed and the portion where the adhesive of the surface protection film is in contact If there is, it remains as a trace of bubbles (sometimes called bubble bubbles). Therefore, it is a very strict evaluation method as a method for evaluating the contamination on the surface of the adherend. In recent years, there has been a demand for a surface protective film that does not have a problem of contamination on the surface of an adherend even as a result of such strict evaluation.

  An adhesive containing an antistatic agent for keeping the peeling voltage low in order to prevent the occurrence of problems caused by the high peeling voltage when the surface protective film is peeled off from the optical film as the adherend. A surface protective film using an agent layer has been proposed.

For example, Patent Document 1 discloses a surface protective film using an adhesive made of an alkyltrimethylammonium salt, a hydroxyl group-containing acrylic polymer, and a polyisocyanate.
Patent Document 2 discloses a pressure-sensitive adhesive composition comprising an ionic liquid and an acrylic polymer having an acid value of 1.0 or less, and a pressure-sensitive adhesive sheet using the same.
Patent Document 3 discloses a pressure-sensitive adhesive composition comprising an alkali metal salt treated with an acrylic polymer, a polyether polyol compound, an anion adsorbing compound, and a surface protective film using the same.
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 less, and a surface protective film using the same.
Patent Document 5 discloses a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet used for a surface protective sheet of an optical member made of a polymer containing a liquid ion salt.

JP 2005-131957 A Japanese Patent Laying-Open No. 2005-330464 JP 2005-314476 A JP 2006-152235 A JP 2008-0669261 A

  In said patent documents 1-5, the antistatic agent is added inside the adhesive layer. However, as the thickness of the pressure-sensitive adhesive layer increases, and as the elapsed time after bonding to the adherend passes, the adherend to which the surface protective film is bonded is attached from the pressure-sensitive adhesive layer. The amount of antistatic agent that migrates to the body increases. If the amount of the antistatic agent transferred to the adherend increases, the appearance quality of the optical film as the adherend may decrease, or the adhesiveness of the FPR film may decrease when the FPR film is bonded. is there.

  Another problem arises when the thickness of the pressure-sensitive adhesive layer is reduced in order to reduce the time-dependent increase of the antistatic agent transferred from the pressure-sensitive adhesive layer to the adherend. For example, when used for optical films with irregularities on the surface, such as anti-glare polarizing plates to prevent glare, the pressure-sensitive adhesive layer cannot follow the irregularities on the surface of the optical film, and bubbles may be mixed in. There is a problem that the adhesive force is lowered by reducing the adhesion area between the film and the pressure-sensitive adhesive layer, and the surface protective film is floated or peeled off during use.

  For this reason, it is a surface protective film used for an optical film, and can be used for an optical film having irregularities on the surface, and there is very little contamination to the adherend, and contamination to the adherend over time. There is a demand for a surface protective film that does not increase, and that suppresses the peeling voltage when the surface protective film is peeled off from an adherend.

The present inventors have intensively studied this problem.
In order to reduce the contamination of the adherend and reduce the increase in contamination over time, it is necessary to reduce the amount of the antistatic agent component in the pressure-sensitive adhesive layer presumed to contaminate the adherend. . However, when the amount of the antistatic agent in the pressure-sensitive adhesive layer is reduced, the peeling voltage when the surface protective film is peeled from the adherend becomes high. In view of this, the present inventors have studied a method for reducing the stripping voltage when peeling the surface protective film from the adherend without increasing the absolute amount of the antistatic agent component in the pressure-sensitive adhesive layer.
As a result, a pressure-sensitive adhesive composition containing no antistatic agent is applied to one side of the substrate film, rather than applying and drying a pressure-sensitive adhesive composition containing an antistatic agent to form a pressure-sensitive adhesive layer. After laminating and drying the pressure-sensitive adhesive layer, the surface protective film is peeled off from the optical film as the adherend by applying an appropriate amount of an antistatic agent component only to the surface of the pressure-sensitive adhesive layer. The present inventors have found that the peeling voltage can be kept low at the time.

  The present invention has been made in view of the above circumstances, and can be used for an optical film having irregularities on the surface, has little contamination to the adherend, and has low contamination to the adherend even with time. It is an object of the present invention to provide a surface protective film that does not change and that has excellent anti-peeling performance without deterioration over time, and an optical component using the same.

  In order to solve the above-mentioned problems, the surface protective film of the present invention is formed by coating and drying a pressure-sensitive adhesive composition not containing an antistatic agent on one side of a base film and laminating a pressure-sensitive adhesive layer. By applying an appropriate amount of antistatic agent to the surface of the pressure-sensitive adhesive layer, the contamination on the adherend is kept low, and the peeling voltage when peeling from the optical film as the adherend is kept low. Is the technical idea.

  In order to solve the above problems, the present invention provides a pressure-sensitive adhesive layer formed on one side of a base film made of a transparent resin, and a release film having a release agent layer is pasted on the pressure-sensitive adhesive layer. A surface protective film formed by combining the release film on one side of the resin film with a release agent mainly composed of dimethylpolysiloxane, an antistatic agent that does not react with the release agent, and at least one or more A release agent layer containing an ester plasticizer containing an ether bond is laminated, and the component of the antistatic agent is an ionic compound having a melting point of less than 30 ° C., and the component of the antistatic agent and the above The ester plasticizer is transferred from the release agent layer of the release film to the surface of the pressure-sensitive adhesive layer, and the release voltage when the pressure-sensitive adhesive layer is released from the adherend is reduced. Surface protection To provide a film.

  Moreover, it is preferable that the said adhesive layer bridge | crosslinks the adhesive composition containing a (meth) acrylate copolymer and a crosslinking agent.

  Moreover, it is preferable that the peeling force when peeling the said peeling film from the said adhesive layer is 0.2 N / 50mm or less.

  Moreover, this invention provides the optical component formed by bonding said surface protection film.

The surface protective film of the present invention has little contamination on the adherend, and the low contamination on the adherend does not change over time. Further, the surface protective film of the present invention can be used even if the adherend is an optical film having an uneven surface such as an AG polarizing plate. Further, according to the present invention, it is possible to suppress a peeling voltage generated when peeling from an optical film as an adherend, and to provide a surface protection film having excellent peeling antistatic performance without deterioration over time, and An optical component using can be provided.
According to the surface protective film of the present invention, the surface of the optical film can be reliably protected, so that productivity and yield can be improved.

It is sectional drawing which showed the concept of the surface protection film of this invention. It is sectional drawing which shows the state which peeled off the peeling film from the surface protection film of this invention. It is sectional drawing which showed one of the Examples of the optical component of this invention.

Hereinafter, the present invention will be described in detail based on embodiments.
FIG. 1 is a cross-sectional view showing the concept of the surface protective film of the present invention. The surface protective film 10 has a pressure-sensitive adhesive layer 2 formed on the surface of one side of a transparent base film 1. A release film 5 having a release agent layer 4 formed on the surface of the resin film 3 is bonded to the surface of the pressure-sensitive adhesive layer 2.

As the base film 1 used for the surface protective film 10 according to the present invention, a base film made of a resin having transparency and flexibility is used. Thereby, the external appearance test | inspection of an optical component can be performed in the state which bonded the surface protection film to the optical component which is a to-be-adhered body. The film made of a resin having transparency used as the base film 1 is preferably a polyester film such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, or polybutylene terephthalate. In addition to the polyester film, a film made of another resin can be used as long as it has a required strength and optical suitability. The base film 1 may be an unstretched film or a uniaxially or biaxially stretched film. Moreover, you may control the draw ratio of a stretched film, and the orientation angle of the axial direction formed with crystallization of a stretched film to a specific value.
Although the thickness of the base film 1 used for the surface protection film 10 according to the present invention is not particularly limited, for example, a thickness of about 12 to 100 μm is preferable, and a thickness of about 20 to 50 μm is easy to handle. preferable.
Further, if necessary, an antifouling layer for preventing surface contamination, an antistatic layer, a hard coat layer for preventing scratches, etc. on the surface opposite to the surface on which the adhesive layer 2 of the base film 1 is formed. Can be provided. Further, the surface of the base film 1 may be subjected to easy adhesion treatment such as surface modification by corona discharge and application of an anchor coating agent.

  Further, the pressure-sensitive adhesive layer 2 used in the surface protective film 10 according to the present invention adheres to the surface of the adherend, can be easily peeled off after use, and does not easily contaminate the adherend. If it is, it will not specifically limit, However, When the durability after bonding to an optical film, etc. are considered, it is common to use the adhesive which bridge | crosslinks a (meth) acrylate copolymer.

  As the (meth) acrylate copolymer, main monomers such as n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate and isononyl acrylate, comonomers such as acrylonitrile, vinyl acetate, methyl methacrylate and ethyl acrylate, acrylic acid, Mention may be made of copolymers obtained by copolymerizing functional monomers such as methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, N-methylol methacrylamide, and monomers containing polyoxyalkylene groups such as methoxypolyethylene glycol methacrylate. it can. In the (meth) acrylate copolymer, the main monomer and other monomers may all be (meth) acrylate, and as a monomer other than the main monomer, one or more monomers other than (meth) acrylate are used. May be included. Monomers other than the main monomer can be selected without particular limitation from the above-mentioned comonomers, functional monomers, monomers containing polyoxyalkylene groups, and the like.

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

  Although the thickness of the adhesive layer 2 used for the surface protection film 10 according to the present invention is not particularly limited, for example, a thickness of about 5 to 40 μm is preferable, and a thickness of about 10 to 30 μm is more preferable. Further, the adherend is such that the peel strength (adhesive strength) of the surface protective film to the surface of the adherend is about 0.03 to 0.3 N / 25 mm and has a slight adhesive strength. It is preferable because it is excellent in operability when the surface protective film is peeled off. Moreover, since it is excellent in the operativity at the time of peeling the peeling film 5 from the surface protection film 10, it is preferable that the peeling force when peeling the peeling film 5 from the adhesive layer 2 is 0.2 N / 50mm or less. More preferably, it is 0.14 N / 50 mm or less.

  Moreover, the release film 5 used for the surface protective film 10 according to the present invention includes, on one side of the resin film 3, a release agent mainly composed of dimethylpolysiloxane, an antistatic agent that does not react with the release agent, and at least A release agent layer 4 containing an ester plasticizer containing one or more ether bonds is laminated. In the release film used for the surface protective film according to the present invention, the component of the antistatic agent is preferably an ionic compound having a melting point of less than 30 ° C.

Examples of the resin film 3 include a polyester film, a polyamide film, a polyethylene film, a polypropylene film, and a polyimide film, and a polyester film is particularly preferable because of its excellent transparency and a relatively low price. . The resin film may be an unstretched film or a uniaxially or biaxially stretched film. Moreover, you may control the draw ratio of a stretched film, and the orientation angle of the axial direction formed with crystallization of a stretched film to a specific value.
Although the thickness of the resin film 3 is not particularly limited, for example, a thickness of about 12 to 100 μm is preferable, and a thickness of about 16 to 50 μm is more preferable because it is easy to handle.
Further, if necessary, the surface of the resin film 3 may be subjected to easy adhesion treatment such as surface modification by corona discharge or application of an anchor coating agent.

  Examples of the release agent mainly composed of dimethylpolysiloxane constituting the release agent layer 4 include known silicone release agents such as an addition reaction type, a condensation reaction type, a cationic polymerization type, and a radical polymerization type. Examples of products that are commercially available as addition reaction type silicone release agents include KS-776A, KS-847T, KS-779H, KS-837, KS-778, and KS-830 (manufactured by Shin-Etsu Chemical Co., Ltd.). SRX-211, SRX-345, SRX-357, SD7333, SD7220, SD7223, LTC-300B, LTC-350G, LTC-310 (manufactured by Toray Dow Corning Co., Ltd.), and the like. Examples of products marketed as a condensation reaction type include SRX-290 and SYLOFF-23 (manufactured by Toray Dow Corning Co., Ltd.). Examples of products that are commercially available as a 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. Examples of the product marketed as a radical polymerization type include X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.).

  The antistatic agent constituting the release agent layer 4 has good dispersibility in a release agent solution mainly composed of dimethylpolysiloxane and inhibits curing of the release agent mainly composed of dimethylpolysiloxane. Those that do not are preferred. Further, an antistatic agent that does not react with a release agent mainly composed of dimethylpolysiloxane is preferable in order to transfer the release agent layer 4 to the surface of the adhesive layer 2 and to impart an antistatic function to the adhesive layer 2. . As such an antistatic agent, an ionic compound having a melting point of less than 30 ° C. is suitable.

Examples of the ionic compound having a melting point of less than 30 ° C. include an ionic compound having a cation and an anion, and the cation includes cyclic amidine ions such as imidazolium ions, pyridinium ions, ammonium ions, sulfonium ions, phosphonium ions, and the like. It is done. The anions include C _n H _{2n + 1} COO ⁻ , C _n F _{2n + 1} COO ⁻ , NO ₃ ⁻ , C _n F _{2n + 1} SO ₃ ⁻ , (C _n F _{2n + 1} SO ₂ ) ₂ N ⁻ , (C _n F _{2n + 1} SO ^{_{2) 3 C -, PO 4}} 3-, AlCl 4 -, Al 2 Cl 7 -, ClO 4 -, BF 4 -, PF 6 -, AsF 6 -, SbF 6 - , and the like.
The amount of the antistatic agent added to the release agent containing dimethylpolysiloxane as a main component varies depending on the type of antistatic agent and the degree of affinity with the release agent. The addition amount of the antistatic agent may be set in consideration of a desired stripping voltage, a contamination property to the adherend, an adhesive property, and the like when the surface protective film is peeled from the adherend.

  The ester plasticizer containing at least one ether bond constituting the release agent layer 4 is used to improve the antistatic property of the surface of the pressure-sensitive adhesive layer 2. The plasticizer contained in the release agent layer 4 is preferably a plasticizer with good dispersibility in a release agent solution containing dimethylpolysiloxane as a main component. And the plasticizer which does not inhibit hardening of the release agent which has dimethylpolysiloxane as a main component is preferable. Further, the plasticizer plays a role in assisting the antistatic agent contained in the release agent layer 4 to migrate from the release agent layer 4 to the surface of the pressure-sensitive adhesive layer 2. For this reason, the plasticizer is preferably one that does not react with the release agent mainly composed of dimethylpolysiloxane. As such a plasticizer, an ester plasticizer having at least one ether bond in the molecule is suitable.

  In the ester plasticizer, at least one ether bond present in the molecule is necessary to increase the affinity with the antistatic agent. In the surface protective film according to the present invention, when the release agent layer and the pressure-sensitive adhesive layer are in contact with each other, a plasticizer is added to efficiently transfer the antistatic agent component from the release agent layer to the surface of the pressure-sensitive adhesive layer. Used. In the present invention, a plasticizer having an ester group is suitable for increasing the affinity between the release agent layer and the pressure-sensitive adhesive layer.

  Examples of the ester plasticizer having at least one ether bond in the molecule include diethylene glycol di-2-ethylhexonate, tetraethylene glycol di-2-ethylhexonate, and hexaethylene glycol diester. 2-ethyl hexonate, triethylene glycol diethyl butyrate, polyethylene glycol diethyl butyrate, polypropylene glycol diethyl hexonate, triethylene glycol dibenzoate, tetraethylene glycol dibenzoate, polyethylene glycol dibenzoate, polypropylene glycol dibenzoate, Alternatively, polyethylene glycol-2-ethylhexonate benzoate and the like can be mentioned. One or two or more selected from these ester plasticizer groups are used in combination. Here, ethyl hexonate is also referred to as ethylhexanoate, ethylhexoate, ethylhexanoate, or the like. Benzoate means benzoate ester.

  The amount of ester plasticizer added to the release agent based on dimethylpolysiloxane varies depending on the type of plasticizer and the degree of affinity with the release agent, but when the surface protective film is released from the adherend. It may be set in consideration of the desired stripping voltage, contamination on the adherend, adhesive properties, and the like.

  There is no particular limitation on the method of mixing the release agent mainly composed of dimethylpolysiloxane, the antistatic agent and the ester plasticizer. A method in which an antistatic agent and an ester plasticizer are added to a release agent mainly composed of dimethylpolysiloxane, and after mixing, a catalyst for curing the release agent is added and mixed, and a release mainly comprising dimethylpolysiloxane. After the agent is diluted with an organic solvent in advance, an antistatic agent, an ester plasticizer, and a catalyst for curing the release agent are added and mixed. After the release agent based on dimethylpolysiloxane is diluted in an organic solvent in advance Any method may be used, such as a method of adding and mixing a catalyst, and then adding and mixing an antistatic agent and an ester plasticizer. Moreover, you may add the material which assists the antistatic effect, such as adhesion improving agents, such as a silane coupling agent, and the compound containing a polyoxyalkylene group as needed.

  The mixing ratio of the release agent mainly composed of dimethylpolysiloxane, and the antistatic agent and the ester plasticizer is not particularly limited, but with respect to the solid content 100 of the release agent mainly composed of dimethylpolysiloxane, A ratio of about 5 to 100 is preferable in which the total of the antistatic agent and the ester plasticizer is a solid content. When the total solid content addition amount of the antistatic agent and the ester plasticizer is less than 5 based on the solid content 100 of the release agent mainly composed of dimethylpolysiloxane, The amount of transfer of the antistatic agent and the ester plasticizer is also reduced, and the antistatic function is hardly exhibited in the adhesive. Further, when the total amount of the antistatic agent and the ester plasticizer in terms of solid content exceeds 100, the antistatic agent and the ester when the total amount of the solid content of the release agent based on dimethylpolysiloxane exceeds 100. Since the release agent mainly composed of dimethylpolysiloxane together with the plasticizer is also transferred to the surface of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive properties of the pressure-sensitive adhesive may be reduced.

  The method for forming the pressure-sensitive adhesive layer 2 and the method for laminating the release film 5 on the base film 1 of the surface protective film 10 according to the present invention may be carried out by known methods and are not particularly limited. Specifically, (1) A method of pasting the release film 5 after applying and drying a resin composition for forming the pressure-sensitive adhesive layer 2 on one side of the base film 1 and forming a pressure-sensitive adhesive layer. (2) After the resin composition for forming the pressure sensitive adhesive layer 2 is applied and dried on the surface of the release film 5 to form the pressure sensitive adhesive layer, the base film 1 is pasted. However, any method may be used.

  Moreover, what is necessary is just to perform the adhesive layer 2 on the surface of the base film 1 by a well-known method. Specifically, known coating methods such as reverse coating, comma coating, gravure coating, slot die coating, Mayer bar coating, and air knife coating can be used.

  Similarly, the release agent layer 4 may be formed on the resin film 3 by a known method. Specifically, known coating methods such as gravure coating, Mayer bar coating, and air knife coating can be used.

  The surface protective film 10 according to the present invention having the above-described configuration preferably has a surface potential of +0.7 kV to −0.7 kV when the pressure-sensitive adhesive layer is peeled off from the optical film as an adherend. . Furthermore, the surface potential is more preferably +0.5 kV to −0.5 kV, and the surface potential is particularly preferably +0.1 kV to −0.1 kV. This surface potential can be adjusted by adjusting the type and amount of the antistatic agent and ester plasticizer contained in the release agent layer.

FIG. 2 is a cross-sectional view showing a state where the release film is peeled off from the surface protective film of the present invention.
By peeling off the release film 5 from the surface protection film 10 shown in FIG. 1, a part of the antistatic agent and ester plasticizer (symbol 7) contained in the release agent layer 4 of the release film 5 becomes a surface protection film. It is transferred (attached) to the surface of the ten pressure-sensitive adhesive layers 2. Therefore, in FIG. 2, the antistatic agent and the ester plasticizer transferred to the surface of the pressure-sensitive adhesive layer 2 of the surface protective film 11 in a state where the release film has been peeled are schematically shown by the dots 7. . When the component 7 of the antistatic agent and the ester plasticizer is transferred from the release film 5 to the surface of the pressure-sensitive adhesive layer 2, the pressure-sensitive adhesive layer 2 is adhered to the adherend layer 2 as compared with the pressure-sensitive adhesive layer 2 before transfer. The stripping voltage when peeling from is reduced. In addition, the peeling voltage at the time of peeling an adhesive layer from a to-be-adhered body can be measured by a well-known method. For example, after the surface protective film is bonded to an adherend such as a polarizing plate, the surface of the adherend is peeled off at a peeling speed of 40 m / min using a high-speed peel tester (manufactured by Tester Sangyo). The maximum value of the absolute value of the surface potential when the surface potential is measured every 10 ms using a surface potentiometer (manufactured by Keyence Co., Ltd.) is measured as the stripping voltage (kV).
In the surface protective film according to the present invention, the antistatic material transferred to the surface of the pressure-sensitive adhesive layer 2 when the surface protective film 11 in a state where the release film shown in FIG. The agent and the ester plasticizer come into contact with the surface of the adherend. As a result, the stripping voltage when the surface protective film is peeled off from the adherend can be kept low.

FIG. 3 is a cross-sectional view showing an embodiment of the optical component of the present invention.
The release film 5 is peeled off from the surface protective film 10 of the present invention, and the pressure-sensitive adhesive layer 2 is exposed, and is bonded to the optical component 8 that is an adherend through the pressure-sensitive adhesive layer 2.
That is, FIG. 3 shows the optical component 20 to which the surface protective film 11 of the present invention is bonded. Examples of the optical component include optical films such as a polarizing plate, a retardation plate, a lens film, a polarizing plate that also serves as a retardation plate, and a polarizing plate that also serves as a lens film. Such an optical component is used as a constituent member of a liquid crystal display device such as a liquid crystal display panel and an optical system device of various instruments. Examples of the optical component include optical films such as an antireflection film, a hard coat film, and a transparent conductive film for a touch panel.
According to the optical component of the present invention, when the surface protective film 11 is peeled and removed from the adherend optical component (optical film), the peeling voltage can be suppressed sufficiently low. Therefore, there is no fear of destroying circuit components such as a driver IC, a TFT element, and a gate line driving circuit, and the production efficiency in the process of manufacturing a liquid crystal display panel and the like can be improved and the reliability of the production process can be maintained.

Next, the present invention will be further described with reference to examples.
Example 1
(Production of surface protective film)
Addition reaction type silicone (product name: SRX-345, manufactured by Toray Dow Corning Co., Ltd.), 5 parts by weight, tri-n-butylmethylammonium bistrifluoromethanesulfonimide (3M) which is an ionic compound having a melting point of 27.5 ° C FC-4400) 7.5% by weight of 10% ethyl acetate solution, 0.75 part by weight of tetraethylene glycol di-2-ethylhexonate, 95 parts by weight of 1: 1 mixed solvent of toluene and ethyl acetate, platinum A catalyst (Toray Dow Corning Co., Ltd., product name: SRX-212) 0.05 parts by weight was mixed and stirred and mixed to prepare a coating material for forming the release agent layer of Example 1. A paint for forming the release agent layer of Example 1 was applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm with a Mayer bar so that the thickness after drying was 0.2 μm, and a 120 ° C. hot air circulation oven And dried for 1 minute to obtain a release film of Example 1. On the other hand, with respect to 100 parts by weight of a 30% ethyl acetate solution of a pressure-sensitive adhesive polymer comprising 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. The pressure-sensitive adhesive composition of Example 1 was prepared by stirring and mixing 1.5 parts by weight of an isocyanate curing agent (product name: Coronate (registered trademark) HX, manufactured by Tosoh Corporation). Coronate (registered trademark) HX is an HDI (hexamethylene diisocyanate) curing agent.
The pressure-sensitive adhesive composition of Example 1 was applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm so that the thickness after drying was 20 μm, and then dried in a hot air circulation oven at 100 ° C. for 2 minutes for adhesion. An agent layer was formed. Then, the release film of Example 1 produced above was bonded to the surface of this pressure-sensitive adhesive layer via a release agent layer (silicone-treated surface). The obtained pressure-sensitive adhesive film was kept warm at 40 ° C. for 5 days, and the pressure-sensitive adhesive layer was cured to obtain the surface protective film of Example 1.

(Comparative Example 1)
Addition-reaction type silicone (manufactured by Toray Dow Corning Co., Ltd., product name: SRX-345), 95 parts by weight of 1: 1 mixed solvent of toluene and ethyl acetate, platinum catalyst (manufactured by Toray Dow Corning Co., Ltd.) Product name: SRX-212) 0.05 parts by weight were mixed and stirred and mixed to prepare a coating material for forming the release agent layer of Comparative Example 1. A paint for forming the release agent layer of Comparative Example 1 was applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm with a Mayer bar so that the thickness after drying was 0.2 μm, and a 120 ° C. hot air circulation oven And dried for 1 minute to obtain a release film of Comparative Example 1. On the other hand, with respect to 100 parts by weight of the pressure-sensitive adhesive polymer solution of Example 1 (ethyl acetate solution having a solid content of 30%), tri-n-butylmethylammonium bistrifluoromethanesulfone, which is an ionic compound having a melting point of 27.5 ° C. 3 parts by weight of imido (3M FC-4400) 10% ethyl acetate solution and 1.5 parts by weight of an isocyanate curing agent (manufactured by Tosoh Corporation, product name: Coronate (registered trademark) HX) were stirred and mixed. The pressure-sensitive adhesive composition of Comparative Example 1 was prepared.
The pressure-sensitive adhesive composition of Comparative Example 1 was applied to the surface of a polyethylene terephthalate film having a thickness of 38 μm so that the thickness after drying was 20 μm, and then dried in a hot air circulation oven at 100 ° C. for 2 minutes for adhesion. An agent layer was formed. Thereafter, the release agent layer (silicone-treated surface) of the release film of Comparative Example 1 prepared above was bonded to the surface of this pressure-sensitive adhesive layer. The obtained pressure-sensitive adhesive film was kept warm at 40 ° C. for 5 days, and the pressure-sensitive adhesive layer was cured to obtain a surface protective film of Comparative Example 1.

(Comparative Example 2)
The surface of Comparative Example 2 was the same as Comparative Example 1 except that tri-n-butylmethylammonium bistrifluoromethanesulfonimide, which is an ionic compound having a melting point of 27.5 ° C., was not added to the adhesive layer. A protective film was obtained.

(Comparative Example 3)
A surface protective film of Comparative Example 3 was obtained in the same manner as in Example 1 except that tetraethylene glycol di-2-ethylhexonate, which is an ester plasticizer, was not added to the release agent layer.

(Example 2)
Instead of the pressure-sensitive adhesive composition of Example 1, a 30% ethyl acetate solution of a pressure-sensitive adhesive polymer comprising a copolymer of 58 parts by weight of 2-ethylhexyl acrylate, 38 parts by weight of butyl acrylate and 4 parts by weight of 2-hydroxyethyl acrylate 100 Example 1 except that 1.2 parts by weight of an isocyanate-based curing agent (product name: Coronate (registered trademark) HX) manufactured by Tosoh Co., Ltd. was added and mixed with respect to parts by weight. Similarly, the surface protective film of Example 2 was obtained.

(Example 3)
Instead of the pressure-sensitive adhesive composition of Example 1, 96 parts by weight of 2-ethylhexyl acrylate, 4 parts by weight of 2-hydroxyethyl acrylate, 100 parts by weight of a 30% ethyl acetate solution of a pressure-sensitive adhesive polymer, The same procedure as in Example 1 except that 1.2 parts by weight of an isocyanate curing agent (product name: Coronate (registered trademark) HX, manufactured by Tosoh Corporation) was added and mixed, and the example was used. 3 surface protective film was obtained.

The evaluation test methods and results are shown below.
<Measurement method of peel strength of release film>
A sample of the surface protective film is cut into a width of 50 mm and a length of 150 mm. In a test environment of 23 ° C. × 50% RH, the strength when the release film was peeled in the direction of 180 ° at a peel rate of 300 mm / min was measured using a tensile tester, and this was measured as the peel strength ( N / 50 mm).

<Measurement method of adhesive strength of surface protective film>
An anti-glare low reflection treatment polarizing plate (AG-LR polarizing plate) was bonded to the surface of the glass plate with a double-sided adhesive tape using a bonding machine. Thereafter, a surface protective film cut to a width of 25 mm was bonded to the surface of the polarizing plate, and then stored for 1 day in a test environment of 23 ° C. × 50% RH. Then, the strength when the surface protective film was peeled in the direction of 180 ° at a peeling speed of 300 mm / min was measured using a tensile tester, and this was defined as adhesive strength (N / 25 mm).

<Measuring method of peeling voltage of surface protective film>
An anti-glare low reflection treatment polarizing plate (AG-LR polarizing plate) was bonded to the surface of the glass plate with a double-sided adhesive tape using a bonding machine. Thereafter, a surface protective film cut to a width of 25 mm was bonded to the surface of the polarizing plate, and then stored for 1 day in a test environment of 23 ° C. × 50% RH. Thereafter, the surface potential of the polarizing plate surface was measured using a surface potentiometer (manufactured by Keyence Corporation) while peeling the surface protective film at a peeling speed of 40 m / min using a high speed peel tester (manufactured by Tester Sangyo). The maximum value of the absolute value of the surface potential when measured every 10 ms was defined as the stripping voltage (kV).

<Method for confirming surface contamination of surface protective film>
An anti-glare low reflection treatment polarizing plate (AG-LR polarizing plate) was bonded to the surface of the glass plate with a double-sided adhesive tape using a bonding machine. Thereafter, a surface protective film cut to a width of 25 mm was bonded to the surface of the polarizing plate, and then stored for 3 days and 30 days in a test environment of 23 ° C. × 50% RH. 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. As criteria for determining surface contamination, the case where there was no migration of contamination on the polarizing plate was marked with (◯), and the case where the migration of contamination was confirmed on the polarizing plate was marked with (×).

  About the obtained surface protection film of Examples 1-3 and Comparative Examples 1-3, the measured measurement result was shown to Tables 1-2. “2EHA” is 2-ethylhexyl acrylate, “# 400G” is methoxypolyethylene glycol (400) methacrylate, “HEA” is 2-hydroxyethyl acrylate, “BA” is butyl acrylate, “FC4400” is Tri-n-butylmethylammonium bistrifluoromethanesulfonimide, “plasticizer” means tetraethylene glycol di-2-ethylhexonate, respectively. In Tables 1 and 2, the composition of the pressure-sensitive adhesive layer is expressed in parts by weight so that the total amount of the pressure-sensitive adhesive polymer (solid content) is about 100 parts by weight. Therefore, in the pressure-sensitive adhesive layer of Comparative Example 1, the weight ratio of the pressure-sensitive adhesive polymer (solid content) to FC4400 is 30 parts by weight: 0.3 part by weight = 100 parts by weight: 1.0 part by weight.

From the measurement results shown in Table 1 and Table 2, the following can be understood.
The surface protective films of Examples 1 to 3 according to the present invention have appropriate adhesive strength, do not contaminate the surface of the adherend, and are peeled off when the surface protective film is peeled from the adherend. The voltage is low.
On the other hand, the surface protective film of Comparative Example 1 in which the antistatic agent is contained in the pressure-sensitive adhesive layer has a low and low peel voltage when the surface protective film is peeled off from the adherend. The contamination to the kimono increased.
Further, in the surface protective film of Comparative Example 2 in which the antistatic agent is not contained in both the pressure-sensitive adhesive layer of the surface protective film and the release agent layer of the release film, the contamination property to the adherend is good. The peeling voltage when the protective film was peeled off from the adherend increased.
That is, the antistatic agent is contained in any of the surface protective film of Comparative Example 1 in which the antistatic agent is contained in the pressure-sensitive adhesive layer of the surface protective film, and the adhesive layer of the surface protective film and the release agent layer of the release film. In the case of the surface protective film of Comparative Example 2 that has not been made, it is difficult to achieve both reduction of the peeling voltage and contamination to the adherend.
On the other hand, after the antistatic agent and the ester plasticizer were contained in the release agent layer of the release film, the antistatic agent and the ester plasticizer of the release agent layer were transferred only to the surface of the adhesive layer. In the surface protective films of Examples 1 to 3, the addition of a small amount of an ester plasticizer has a remarkable effect of reducing the peeling voltage, so there was no contamination of the adherend and the antistatic property of peeling was good.
Further, in the surface protective film of Comparative Example 3 in which only the antistatic agent was contained in the release agent layer and no ester plasticizer was contained, the adherend was not contaminated and the release antistatic performance was good. However, as compared with the surface protective films of Examples 1 to 3 in which the release agent layer contained an antistatic agent and an ester plasticizer, the release voltage was higher.

  The surface protective film of the present invention is, for example, an optical film such as a polarizing plate, a retardation plate, a lens film, and the like, and in other production processes such as various optical components. Can be used to protect. In addition, the surface protective film of the present invention can reduce the amount of static electricity generated when peeling from the adherend, and the change in antistatic performance against peeling and the contamination of the adherend are small, improving the yield of the production process. The industrial utility value is great.

DESCRIPTION OF SYMBOLS 1 ... Base film, 2 ... Adhesive layer, 3 ... Resin film, 4 ... Release agent layer, 5 ... Release film, 7 ... Antistatic agent and ester plasticizer, 8 ... Adhering body (optical component), 10 ... surface protective film, 11 ... surface protective film from which the release film has been peeled off, 20 ... optical component bonded with the surface protective film.

Claims (4)

Release film for antistatic surface protective film capable of transferring antistatic agent to surface of adhesive layer of antistatic surface protective film having adhesive layer formed on one side of base film made of resin having transparency Because
The release film for an antistatic surface protective film contains a release agent mainly composed of dimethylpolysiloxane, an antistatic agent that does not react with the release agent, and at least one ether bond on one surface of the resin film. A laminate of a release agent layer containing an ester plasticizer,
The antistatic agent component is an ionic compound having a melting point of less than 30 ° C .;
When the release film for an antistatic surface protective film is bonded to the pressure-sensitive adhesive layer via the release agent layer, the antistatic agent component of the release agent layer and the ester plasticizer are bonded to the pressure-sensitive adhesive layer. A release film for an antistatic surface protective film, which can be transferred to the surface of an agent layer.   The release film for an antistatic surface protective film according to claim 1, wherein the pressure-sensitive adhesive layer is obtained by crosslinking a pressure-sensitive adhesive composition containing a (meth) acrylate copolymer and a crosslinking agent. .   The ester plasticizer is diethylene glycol di-2-ethyl hexonate, tetraethylene glycol di-2-ethyl hexonate, hexaethylene glycol di-2-ethyl hexonate, triethylene glycol diethyl butyrate, polyethylene glycol Selected from the group consisting of diethyl butyrate, polypropylene glycol diethyl hexonate, triethylene glycol dibenzoate, tetraethylene glycol dibenzoate, polyethylene glycol dibenzoate, polypropylene glycol dibenzoate, and polyethylene glycol-2-ethylhexonate benzoate The release film for an antistatic surface protective film according to claim 1, wherein the release film is one or more types.   The surface protection film for optical films by which the peeling film for antistatic surface protection films in any one of Claims 1-3 is bonded.

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