JP6382169B2 - Surface protective film and optical component on which it is bonded - Google Patents

Description

The present invention relates to a surface protective film bonded to the surface of an optical component (hereinafter sometimes referred to as an optical film). More specifically, the present invention relates to providing a surface protective film that is less contaminated on the adherend and that does not change the contamination on the adherend over time, and an optical component using the same. In addition, the present invention can protect the surface even if the constituent member of the polarizing plate, which is an optical component, is replaced (change from TAC film to acrylic film or polyester film, or change from water-based adhesive to UV-curable adhesive). The present invention provides a surface protective film that suppresses a peeling voltage when peeling a film, and an optical component on which the surface protective film is bonded.
In addition, the optical component in this invention has pointed out the polarizing film, the phase difference plate, the lens film for a display, etc.

  Manufacture and transport 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 same. In some cases, 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.

  Conventionally, a surface protective film provided with a pressure-sensitive adhesive layer on one surface of a base film is generally used in order to prevent adhesion of scratches and dirt in the manufacturing process of optical products. 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 a liquid crystal display panel production process, a driver for controlling the display screen of a liquid crystal display by means of a stripping 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 an IC are destroyed and a phenomenon in which the alignment 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 along with this, 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.

  Further, a conventional polarizing plate is obtained by adhering a triacetyl cellulose film (TAC film) with a water-based adhesive on both sides of a polarizer made of polyvinyl alcohol (PVA) impregnated with iodine to protect the polarizer. In recent years, instead of the TAC film, a polarizing plate using an acrylic film, a cyclic polyolefin film or a polyester film, or a polarizing plate using an ultraviolet curable adhesive instead of a water-based adhesive is also used. It is supposed to be. Due to the change in the constituent material of the polarizing plate, there is a problem that the peeling voltage generated when the surface protective film is peeled off and removed becomes higher than when the polarizing plate having the conventional configuration is used.

  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.

  On the other hand, 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 can pass the judgment by such a strict evaluation method and has very little contamination on the surface of an adherend.

  After the surface protective film is bonded to the adherend optical film, the peeling voltage is generated to prevent problems caused by the high peeling voltage, which occurs when the surface protective film is peeled off from the adherend. A surface protective film using a pressure-sensitive adhesive layer containing an antistatic agent to keep it low is 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 an adhesive composition composed of 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.

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

  In the surface protective films described in Patent Documents 1 to 4, an antistatic agent is added inside the pressure-sensitive adhesive layer. Therefore, as the thickness of the pressure-sensitive adhesive layer increases, and as the elapsed time after bonding to the adherend passes, the adherend from the pressure-sensitive adhesive layer adheres to the adherend to which the surface protective film is bonded. There was a tendency for the amount of antistatic agent to migrate to the body to increase. In addition, when the amount of the antistatic agent transferred to the adherend increases, the appearance quality of the optical film as the adherend decreases, or when the FPR film is bonded, the adhesiveness of the FPR film decreases. there's a possibility that.

  If the thickness of the pressure-sensitive adhesive layer is reduced in order to reduce the change with time of the antistatic agent transferred from the pressure-sensitive adhesive layer to the adherend, another problem arises. 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.

  In addition, in order to reduce the time-dependent change of the antistatic agent transferred from the adhesive layer to the adherend, the surface protective film is peeled off from the adherend when the amount of the antistatic agent added to the adhesive layer is reduced. As a result, the stripping voltage generated upon removal increases, and there is a risk that a circuit component such as a driver IC is destroyed or a liquid crystal molecule alignment is damaged.

The present invention has been made in view of the above circumstances, and is a surface protective film that is bonded to the surface of an optical film, and can be bonded even to an optical film having irregularities on the surface. It is an object of the present invention to provide a surface protective film that has very little contamination on the adherend and that does not change the low contamination on the adherend even over time, and an optical component using the same.
In addition, the present invention can protect the surface even if the constituent member of the polarizing plate, which is an optical component, is replaced (change from TAC film to acrylic film or polyester film, or change from water-based adhesive to UV-curable adhesive). It is an object of the present invention to provide a surface protective film in which a peeling voltage when peeling a film is suppressed, and an optical component using the same.

The present inventors have intensively studied to solve these problems. In order to reduce the contamination of the adherend and reduce the change in contamination over time, it is necessary to reduce the content of the antistatic agent, which is presumed to be a cause of contamination of the adherend. However, when the content of the antistatic agent is reduced, the peeling voltage when the surface protective film is peeled from the adherend becomes high.
Therefore, the present inventors have studied a method for suppressing the peeling voltage when peeling the surface protective film from the adherend without increasing the content of the antistatic agent.

  The inventors first applied a pressure-sensitive adhesive composition containing no antistatic agent to one side of the substrate and dried to laminate a pressure-sensitive adhesive layer, and then contained an antistatic agent on the other side of the substrate. The surface protection film which laminated | stacked the release agent layer to make was created. After that, the surface protective film is wound into a roll shape so that the pressure-sensitive adhesive layer is on the inside, whereby the antistatic agent component contained in the release agent layer is transferred to the surface of the pressure-sensitive adhesive layer. As a result, it was present only on the surface of the pressure-sensitive adhesive layer. Once this surface protective film is bonded to an optical film, which is an adherend, the stripping voltage when peeling from the adherend is kept low, and it is found that the adherend is difficult to contaminate. The present invention has been completed.

  The surface protective film of the present invention has a pressure-sensitive adhesive composition that does not contain an antistatic agent applied to one side of the substrate and is dried to laminate a pressure-sensitive adhesive layer, and contains the antistatic agent on the other side of the substrate. After the release agent layer is laminated, the surface protective film is wound so that the pressure-sensitive adhesive layer is on the inside and rolled to form a charge contained in the release agent layer on the surface of the pressure-sensitive adhesive layer. The inhibitor component is transferred. In the present invention, when the surface protection film wound in a roll shape is rewound from the roll shape and bonded to the adherend, the contamination with respect to the adherend is suppressed to a low level. The technical idea is to suppress the peeling voltage when peeling the surface protective film from a certain optical film.

  In order to solve the above problems, the present invention is such that a release agent layer is formed on one surface of a base film made of a resin having transparency, and an adhesive layer is formed on the other surface of the base film. A surface protective film formed, wherein the release agent layer contains an antistatic agent made of an alkali metal salt and a silicone release agent, and the alkali metal salt contained in the release agent layer. An antistatic agent component is provided only on the surface of the pressure-sensitive adhesive layer.

  Moreover, it is preferable that the said adhesive layer is an acrylic adhesive layer containing the crosslinked (meth) acrylate copolymer.

  Moreover, it is preferable that the surface potential at the time of peeling the said adhesive layer from the optical film which is a to-be-adhered body is +0.7 kV--0.7 kV.

  Moreover, it is preferable that the said base film is wound in the shape of a roll with the said adhesive layer facing inside so that the said peeling agent layer and the said adhesive layer may contact | connect.

  Moreover, this invention provides the optical component by which said surface protection film is bonded through the said adhesive layer.

The surface protective film of the present invention is a surface protective film that is bonded to the surface of an optical film, and can also be bonded to an optical film having irregularities on the surface.
In addition, according to the present invention, it is possible to provide a surface protective film in which the contamination of the adherend is very small and the contamination of the adherend does not change over time, and an optical component using the same.
Furthermore, according to the present invention, the components of the polarizing plate, which is an optical component, are changed (change from a TAC film to an acrylic film, a cyclic polyolefin film, or a polyester film, or from an aqueous adhesive to an ultraviolet curable adhesive). Even so, it is possible to provide a surface protective film in which the peeling voltage when peeling the surface protective film is kept low, and an optical component using the same.
In addition, the surface protective film wound into a roll of the present invention is a surface protective film in which the base film is wound into a roll with the pressure-sensitive adhesive layer inside so that the release agent layer and the pressure-sensitive adhesive layer are in contact with each other. The component of the antistatic agent composed of the alkali metal salt is transferred from the release agent layer to the surface of the pressure-sensitive adhesive layer and exists only on the surface of the pressure-sensitive adhesive layer.
That is, in the present invention, after the surface protective film unwound from the roll-wrapped surface protective film is bonded to the adherend, the peeling voltage when the surface protective film is peeled from the adherend is reduced. And, since it has little change over time in peeling antistatic performance and less contamination to the adherend, it has the feature that it can improve the productivity of optical parts that are adherends and improve the yield. .

It is a conceptual sectional view showing the surface protection film in the state wound in the shape of a roll of the present invention. It is a conceptual sectional view showing the state where the release agent layer and the pressure-sensitive adhesive layer are in contact with each other in a state where the surface protective film of the present invention is wound into a roll. It is sectional drawing which shows one of the Examples which bonded the surface protection film of this invention to the optical component.

Hereinafter, the present invention will be described in detail based on embodiments.
FIG. 1 is a conceptual cross-sectional view showing a surface protective film 10 in a state of being wound in a roll according to the present invention. The surface protective film 10 in a rolled state shown on the right side of FIG. 1 is a surface protective film 5 according to the present invention wound in a roll shape with the adhesive layer 4 inside (surface protective film). 5 roll body). Moreover, the left side of FIG. 1 is a conceptual cross-sectional view showing the surface protective film 5 rewound from the roll shape in the direction of the arrow, enlarged in the thickness direction.

  This surface protective film 5 has a release agent layer 2 containing an antistatic agent 3 made of an alkali metal salt on one surface of a transparent substrate film 1, and has an adhesive on the other surface of the substrate film 1. An agent layer 4 is formed. The release agent layer 2 and the adhesive layer 4 are in contact with the surface protective film 5 having the release agent layer 2 on one surface of the base film 1 and the adhesive layer 4 on the other surface of the base film. As described above, by winding the adhesive layer 4 in a roll shape, the components of the antistatic agent 3 contained in the release agent layer 2 are transferred to the surface of the adhesive layer 4. The surface protective film 10 in a state of being wound in a roll shape that exists only on the surface is obtained.

As the base film 1 used for the surface protective film 5 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 5 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 protective film 5 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 75 μm is easy to handle. preferable.
If necessary, the surface of the substrate film 1 may be subjected to easy adhesion treatment such as surface modification by corona discharge and application of an anchor coating agent.

  The release agent layer 2 formed on the surface protective film 5 according to the present invention is formed using a release agent containing an antistatic agent 3 made of an alkali metal salt. As the release agent, a silicone release agent is preferably used.

  Examples of the silicone release agent 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, SYLOFF-23 (manufactured by Toray Dow Corning Co., Ltd.), and the like. Examples of products marketed 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 3 contained in the release agent layer 2 is preferably one that has good dispersibility in the silicone release agent solution and does not inhibit the curing of the silicone release agent. Further, the antistatic agent 3 component contained in the release agent layer 2 is transferred to the surface of the adhesive layer 4 that is in contact with the release agent layer 2, and the antistatic function is applied to the surface of the adhesive layer 4. Therefore, an antistatic agent that does not react with the silicone release agent is preferable. As such an antistatic agent, an alkali metal salt is suitable.

Examples of the alkali metal salt include metal salts composed of lithium, sodium, and potassium. Specifically, for example, a cation selected from Li ⁺ , Na ⁺ , K ⁺ and Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SCN ⁻ , ClO ₄ ⁻ , CF ₃ SO _{3 ^{-, (CF 3 sO 2)}} 2 N -, (C 2 F 5 sO 2) 2 N -, (CF 3 sO 2) 3 C - metal salt composed of anions selected from is preferably used. Among these, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (CF ₃ A lithium salt such as SO ₂ ) ₃ C is preferably used. These alkali metal salts may be used alone or in combination of two or more. In order to stabilize the ionic substance, a compound containing a polyoxyalkylene structure may be added.

  The amount of antistatic agent added to the silicone release agent varies depending on the type of antistatic agent and the degree of affinity with the silicone release agent, but the desired release when peeling the surface protective film from the adherend. What is necessary is just to set in consideration of a charged voltage, the contamination | pollution property with respect to a to-be-adhered body, an adhesive characteristic, etc. The mixing ratio (weight ratio) of the silicone release agent and the antistatic agent is preferably set to a ratio of 5 to 100 with the antistatic agent as the solid content with respect to the solid content 100 of the silicone release agent, for example. It is a value and it is still more preferable to set it as the ratio of 5-60. If the addition amount of the antistatic agent in terms of solid content is less than 5 with respect to the solid content 100 of the silicone release agent, the transfer amount of the antistatic agent to the surface of the adhesive layer is also reduced, The antistatic function is hardly exhibited. Moreover, when the addition amount of the antistatic agent in terms of solid content exceeds a ratio of 100 to the solid content 100 of the silicone release agent, the components of the silicone release agent together with the antistatic agent are also present on the surface of the adhesive layer. Since it is transferred, the adhesive property of the adhesive may be reduced.

  The release agent layer 2 comprises at least a silicone release agent and an antistatic agent that does not react with the release agent. There is no particular limitation on the method of mixing the silicone release agent and the antistatic agent. A method of adding an antistatic agent to a silicone release agent, mixing and then adding and mixing a catalyst for release agent curing, an antistatic agent and a release agent after diluting the silicone release agent with an organic solvent in advance Any method may be used, such as a method of adding and mixing a curing catalyst, a method of diluting a silicone release agent in an organic solvent in advance, adding and mixing the catalyst, and then adding and mixing an antistatic agent. Moreover, the release agent layer 2 imparts printing properties such as an adhesion improver such as a silane coupling agent, a material for assisting an antistatic effect such as a compound containing a polyoxyalkylene group, and a cellulose compound, as necessary. The material which adjusts, the material which adjusts slipperiness, etc. may be contained.

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

In the pressure-sensitive adhesive layer 4 formed on the surface protective film 5 according to the present invention, the component of the antistatic agent 3 contained in the release agent layer 2 does not exist inside the pressure-sensitive adhesive layer 4 (other than the surface). It exists only on the surface of the pressure-sensitive adhesive layer 4. Thereby, the time-dependent change of peeling antistatic performance of the surface protective film 5 and the contamination of the adherend can be suppressed.
The pressure-sensitive adhesive layer 4 formed on the surface protective film 5 according to the present invention is a pressure-sensitive adhesive layer that adheres to the surface of the adherend, can be easily peeled off after use, and does not easily contaminate the adherend. There is no particular limitation. Considering that the durability after the surface protective film 5 according to the present invention is bonded to an optical film is taken into account, it is an acrylic pressure-sensitive adhesive layer obtained by crosslinking a (meth) acrylate copolymer. Is preferred.

  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. In the (meth) acrylate copolymer, the main monomer and other monomers may all be (meth) acrylates, and may include one or more monomers other than (meth) acrylate as monomers other than the main monomer. Good.

  Further, a compound containing a polyoxyalkylene group may be copolymerized or mixed with the (meth) acrylate copolymer. Examples of the compound containing a copolymerizable polyoxyalkylene group include polyethylene glycol (400) monoacrylate, polyethylene glycol (400) monomethacrylate, methoxypolyethylene glycol (400) acrylate, and methoxypolyethylene glycol (400) methacrylate. , Polypropylene glycol (400) monoacrylate, polypropylene glycol (400) monomethacrylate, methoxypolypropylene glycol (400) acrylate, methoxypolypropylene glycol (400) methacrylate, and the like. By copolymerizing these polyoxyalkylene group-containing monomers with the main monomer or functional monomer of the (meth) acrylate copolymer, a pressure-sensitive adhesive made of a copolymer containing a polyoxyalkylene group is obtained. be able to.

  The compound containing a polyoxyalkylene group that can be mixed with the (meth) acrylate copolymer is preferably a (meth) acrylate copolymer containing a polyoxyalkylene group, and a (meth) acrylic containing a polyoxyalkylene group. Polymers of monomers are more preferable. For example, polyethylene glycol (400) monoacrylate, polyethylene glycol (400) monomethacrylate, methoxypolyethylene glycol (400) acrylate, methoxypolyethylene glycol (400) methacrylate, polypropylene glycol ( 400) monoacrylic acid ester, polypropylene glycol (400) monomethacrylic acid ester, methoxypolypropylene glycol (400) acrylate, methoxypolypropylene Polymers, such as glycol (400) methacrylate. By mixing these polyoxyalkylene group-containing compounds with the (meth) acrylate copolymer, a pressure-sensitive adhesive to which a compound containing a polyoxyalkylene group is added can be obtained.

  As a hardening | curing agent added to the adhesive layer 4, an isocyanate compound, an epoxy compound, a melamine compound, a metal chelate compound etc. are mentioned as a crosslinking agent which bridge | crosslinks a (meth) acrylate copolymer. Examples of the tackifier include rosin, coumarone indene, terpene, petroleum, and phenol.

  The thickness of the pressure-sensitive adhesive layer 4 formed on the surface protective film 5 according to the present invention is not particularly limited, but for example, a thickness of about 5 to 40 μm is preferable, and a thickness of about 10 to 30 μm is more preferable. From the adherend to the surface, the peel strength (adhesive strength) of the surface protective film with respect to the surface of the adherend is a pressure-sensitive adhesive layer 4 having a slight adhesive strength of about 0.03 to 0.3 N / 25 mm. It is preferable because it is excellent in operability when the protective film is peeled off.

  The method for forming the pressure-sensitive adhesive layer 4 on the base film 1 of the surface protective film 5 according to the present invention may be performed by a known method, and is not particularly limited. 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.

  The surface protective film 5 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 4 is peeled from the optical film that is an adherend. . Furthermore, the surface potential is more preferably +0.5 kV to −0.5 kV, and the surface potential is particularly preferably +0.2 kV to −0.2 kV. This surface potential can be adjusted by adjusting the type and amount of the antistatic agent 3 contained in the release agent layer 2. Considering the surface contamination property of the optical film as the adherend after the surface protective film 5 is peeled off from the optical film as the adherend, the type and amount of the antistatic agent 3 in the release agent layer 2 Can be adjusted.

  FIG. 2 is a conceptual cross-sectional view showing a state where the release agent layer 2 and the pressure-sensitive adhesive layer 4 are in contact with each other in a state where the surface protective film 5 of the present invention is wound in a roll shape. The release agent layer 2 containing the antistatic agent 3 is formed on one surface of the base film 1, and the adhesive layer 4 not containing the antistatic agent 3 is formed on the other surface of the base film 1. By making the surface protective film 5 formed into a surface protective film 10 in a state of being wound in a roll shape with the pressure-sensitive adhesive layer 4 inside, the release agent layer 2 and the pressure-sensitive adhesive layer 4 in the radial direction of the roll body. Will be in contact with each other. Thereby, a part of the component of the antistatic agent (reference numeral 3) contained in the release agent layer 2 is transferred to the surface of the pressure-sensitive adhesive layer 4. FIG. 3 shows a state in which the surface protective film 5 drawn out from the surface protective film 10 in a roll shape obtained in this way is bonded to the optical component 6. When the component of the antistatic agent 3 is transferred from the release agent layer 2 to the surface of the pressure-sensitive adhesive layer 4, the surface protective film 5 can be compared with the pressure-sensitive adhesive layer 4 before the component of the antistatic agent 3 is transferred. After bonding to the adherend, the peeling voltage when the surface protective film 5 is peeled from the adherend is reduced. In addition, the peeling voltage at the time of peeling the surface protection film 5 of FIG. 1 from a to-be-adhered body can be measured by a well-known method. For example, after the surface protective film 5 is bonded to an adherend such as a polarizing plate, the surface protective film 5 is peeled off at a peeling speed of 40 m / min using a high-speed peel tester (manufactured by Tester Sangyo). When the surface potential of the surface of the adherend is measured every 10 ms using a surface potential meter (manufactured by Keyence Corp.), the maximum value of the absolute value of the surface potential is measured as the peeling voltage (kV).

  In the surface protection film 10 in a state of being wound into a roll according to the present invention, the surface protection film 5 rewound from the roll shape was transferred to the surface of the pressure-sensitive adhesive layer 4 when being bonded to an adherend. The antistatic agent 3 contacts the surface of the adherend. Thereby, it is possible to suppress the peeling voltage when the surface protective film 5 is peeled off from the adherend again. Moreover, in the surface protection film 10 of the state wound in roll shape concerning this invention, since the release agent layer 2 is made into the outer side and the adhesive layer 4 is made into the inner side, the surface of the adhesive layer 4 is in the state of a roll. , Protected without being exposed. Even after the surface protective film 5 is rewound from the roll shape, since the release agent layer 2 is integrated with the base film 1, it is not necessary to remove or discard the release agent layer 2.

  FIG. 3 is a cross-sectional view showing an optical component 7 with a surface protective film as one example in which the surface protective film 5 of the present invention is bonded to an optical component. The optical component 7 with the surface protective film is fed from the surface protective film 10 in a state where the surface protective film 5 of the present invention is wound in a roll shape, and the optical component 6 which is an adherend through the adhesive layer 4. It is obtained by pasting to. Examples of the optical component 6 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, an optical system device of various instruments, and the like. 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.

  The surface protective film 5 of the present invention is unwound from the surface protective film 10 in a rolled state and bonded to an optical component (optical film) as an adherend, and then the surface protective film 5 from the adherend. When stripping and removing, the stripping 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 described in more detail by way of examples.

Example 1
(Production of surface protective film)
Addition reaction type silicone (manufactured by Toray Dow Corning Co., Ltd., product name: SRX-345) 5 parts by weight, lithium bis (fluorosulfonyl) imide 0.75 part by weight, 1: 1 1: 1 mixed solvent of toluene and ethyl acetate Part, platinum catalyst (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 Example 1.
Meanwhile, 90 parts by weight of 2-ethylhexyl acrylate, 7 parts by weight of methoxypolyethylene glycol (400) methacrylate, and 100 parts by weight of 40% ethyl acetate solution of a pressure-sensitive adhesive composed of 3 parts by weight of 2-hydroxyethyl acrylate, The pressure-sensitive adhesive composition of Example 1 was prepared by stirring and mixing 2 parts by weight of an isocyanate curing agent (Coronate (registered trademark) HX manufactured by Tosoh Corporation).
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 For 1 minute to form a release agent layer. Next, after applying the prepared pressure-sensitive adhesive composition to the surface of the polyethylene terephthalate film on which the release agent layer is not formed so that the thickness after drying becomes 20 μm, it is heated in a 100 ° C. hot air circulation oven for 2 minutes. It was made to dry and the adhesive layer was formed. Thereafter, the obtained adhesive film is formed so that the release agent layer is formed on one surface of the base film and the adhesive layer is formed on the other surface, so that the release agent layer and the adhesive layer are in contact with each other. It was wound into a roll with the layer inside. The obtained pressure-sensitive adhesive film wound into a roll was kept warm for 5 days in an environment of 40 ° C., and the pressure-sensitive adhesive layer was cured to obtain a surface protective film wound in the shape of a roll in Example 1.

(Example 2)
A surface protective film in a state of being wound into a roll of Example 2 in the same manner as in Example 1 except that the thickness of the paint forming the release agent layer of Example 1 after drying was 0.1 μm. Obtained.

(Example 3)
Implementation was conducted except that the addition reaction type silicone of Example 1 was made by Toray Dow Corning Co., Ltd., product name: SRX-211, and lithium bis (trifluoromethanesulfonyl) imide was used instead of lithium bis (fluorosulfonyl) imide. In the same manner as in Example 1, a surface protective film in the state of being wound in the roll shape of Example 3 was obtained.

(Comparative Example 1)
A surface protective film in the state of being wound into a roll of Comparative Example 1 was obtained in the same manner as in Example 1 except that lithium bis (fluorosulfonyl) imide as an antistatic agent was not added.

(Comparative Example 2)
Instead of adding lithium bis (fluorosulfonyl) imide to the release agent, except that 0.67 parts by weight of lithium bis (fluorosulfonyl) imide was added to 100 parts by weight of 40% ethyl acetate solution on the adhesive side. In the same manner as in Example 1, a surface protective film in the state of being wound in the roll shape of Comparative Example 2 was obtained.

The evaluation test methods and results are shown below.
<Measuring method of deployment force of surface protective film>
A sample of the surface protection film that has been rewound is cut out from the surface protection film that has been wound into a roll in a state where two layers are overlapped, and cut into a width of 50 mm and a length of 150 mm. In a test environment of 23 ° C. × 50% RH, the strength when peeled in the direction of 180 ° at a peeling speed of 300 mm / min was measured using a tensile tester, and this was measured as the developing force (N / 50 mm).

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

<Measurement method of adhesive strength of surface protective film>
A polarizing plate (AG-LR polarizing plate) subjected to anti-glare low reflection treatment in which an acrylic film was bonded to a polarizer (polyvinyl alcohol film containing iodine) using an ultraviolet curable adhesive was used as an adherend. . This 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 pasted on the acrylic film on the surface of the polarizing plate, and then stored in a test environment of 23 ° C. × 50% RH for 1 day. Then, the strength 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>
A polarizing plate (AG-LR polarizing plate) subjected to anti-glare low reflection treatment in which an acrylic film was bonded to a polarizer (polyvinyl alcohol film containing iodine) using an ultraviolet curable adhesive was used as an adherend. . This 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 pasted on the acrylic film on the surface of the polarizing plate, and then stored in a test environment of 23 ° C. × 50% RH for 1 day. Then, using a surface potentiometer (manufactured by Keyence Corporation), the surface potential of the polarizing plate surface was peeled off 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>
A polarizing plate (AG-LR polarizing plate) subjected to anti-glare low reflection treatment in which an acrylic film was bonded to a polarizer (polyvinyl alcohol film containing iodine) using an ultraviolet curable adhesive was used as an adherend. . This 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 onto the acrylic film on 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 to confirm surface contamination. 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 (×).

Table 1 shows the measurement results of the obtained surface protective films of Examples 1 to 3 and Comparative Examples 1 and 2 wound in a roll shape. “2EHA” is 2-ethylhexyl acrylate, “HEA” is 2-hydroxyethyl acrylate, “# 400G” is methoxypolyethylene glycol (400) methacrylate, “AS agent (1)” is lithium bis (fluorosulfonyl) ) "Imide", "AS agent (2)" is lithium bis (trifluoromethanesulfonyl) imide, "SRX-345" is SRX-345, "SRX-211" is SRX-211, "SRX212" is platinum Catalysts SRX-212 are meant respectively. Moreover, the surface resistivity “4.2E11” means 4.2 × 10 ¹¹ and “overrange” means that the measurement limit of the measuring machine is exceeded, and 1.0 × 10 ¹³ Ω / □ or more is exceeded. means.

From the measurement results shown in Table 1, the following can be understood.
When the surface protective film in the state of being wound into a roll shape in Examples 1 to 3 according to the present invention is used after being unwound from the roll shape, the surface protective film has an appropriate adhesive force, and the surface of the adherend is contaminated. Absent. Moreover, even if the adherend is a polarizing plate using an acrylic film, the peeling voltage when the surface protective film is once bonded to the adherend and then peeled off from the adherend is low.
On the other hand, the surface protection film wound in a roll shape of Comparative Example 1 in which no antistatic agent was added to the release agent layer was once pasted on the adherend. After combining, the peeling voltage when peeling from the adherend increased. Further, instead of containing the antistatic agent in the release agent layer, the surface protection film in a roll shape of Comparative Example 2 in which the antistatic agent is contained in the pressure-sensitive adhesive layer is wound from the roll shape. Once the returned surface protective film is pasted to the adherend, the peeling voltage when peeling from the adherend is low and good, but the contamination to the adherend after peeling the surface protective film Increased.
That is, it is difficult for the surface protective films of Comparative Examples 1 and 2 wound in a roll shape to achieve both a reduction in the stripping voltage and a low contamination to the adherend. On the other hand, the surface protective film in a rolled state of Examples 1 to 3 in which an antistatic agent was added to the release agent layer and the antistatic agent component was transferred only to the surface of the pressure-sensitive adhesive layer was a release band. The reduction of the voltage and the low contamination to the adherend were both compatible.

  The surface protective film of the present invention is, for example, in production processes of optical films such as polarizing plates, retardation plates, lens films, antireflection films, hard coat films, transparent conductive films, and other various optical components. It can be used to protect the surface by bonding to the surface of the optical component or the like. In addition, the surface protective film of the present invention can suppress the peeling voltage generated when the surface protective film is peeled off from the adherend after being bonded to the adherend optical component (optical film), and In addition, the change in the antistatic properties against peeling and the contamination of the adherend are few, the yield of the production process can be improved, and the industrial utility value is great.

DESCRIPTION OF SYMBOLS 1 ... Base film, 2 ... Release agent layer, 3 ... Antistatic agent, 4 ... Adhesive layer, 5 ... Surface protection film, 6 ... Optical component (optical film), 7 ... Optical component with surface protection film, 10: A surface protective film wound in a roll.

Claims (5)

A release agent layer is formed on one surface of a base film made of a resin having transparency,
A surface protective film in which an adhesive layer is formed on the other surface of the base film,
The release agent layer contains an antistatic agent made of an alkali metal salt and a silicone release agent,
A surface protective film, wherein the antistatic agent component comprising the alkali metal salt contained in the release agent layer is present only on the surface of the pressure-sensitive adhesive layer.   The surface protective film according to claim 1, wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer containing a crosslinked (meth) acrylate copolymer.   The surface protective film according to claim 1 or 2, wherein a surface potential at the time of peeling off the pressure-sensitive adhesive layer from an optical film as an adherend is +0.7 kV to -0.7 kV.   The said base film is wound in the shape of a roll with the said adhesive layer inside so that the said release agent layer and the said adhesive layer may contact | connect, The Claim 1 characterized by the above-mentioned. The surface protective film as described.   The optical component by which the surface protection film in any one of Claims 1-4 is bonded through the said adhesive layer.

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