JP2011191768A - Surface protective film for optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface protective film for an optical film, which is used for protecting the surface of an optical film subjected to an activation treatment, wherein a peeling charge amount generated when the surface protective film is peeled from the optical film is reduced and there is no trouble of contamination on the optical film surface after the surface protective film is peeled. <P>SOLUTION: The surface protective film includes a substrate film and a pressure-sensitive adhesive layer, and is stuck to an optical film through the pressure-sensitive adhesive layer of the surface protective film. The surface of the optical film coming in contact with the pressure-sensitive adhesive layer is subjected to an activation treatment. The pressure-sensitive adhesive layer of the surface protective film contains an ionic antistatic agent. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an optical film with a surface protective film in which a protective film is provided on the surface of the optical film. Furthermore, the present invention relates to an image display device such as a liquid crystal display device, an organic EL display device, and a PDP using the optical film with a surface protective film. Examples of the optical film include a polarizing plate, a retardation plate, an optical compensation film, a brightness enhancement film, and a laminate of these.

  In a liquid crystal display or the like, it is indispensable to dispose polarizing elements on both sides of a liquid crystal cell because of its image forming method, and generally a polarizing plate is attached. In addition to polarizing plates, various optical elements have been used for liquid crystal panels in order to improve the display quality of displays. For example, a retardation plate for preventing coloring, a viewing angle widening film for improving the viewing angle of a liquid crystal display, and a brightness enhancement film for increasing the contrast of the display are used. These films are collectively called optical films.

  These optical films are usually bonded with a protective film on the surface so that the surface of the optical film is not scratched or soiled in the transportation or manufacturing process until it is delivered to consumers. The surface protective film may be peeled off after being attached to an LCD or the like, or the same or another surface protective film may be attached again after being peeled once. And when peeling off this surface protection film, static electricity generate | occur | produced and there existed a problem that circuits, such as an LCD panel, were destroyed by this static electricity. Further, there is a problem in that the array element (TFT drive element) inside the LCD panel is affected, which further affects the alignment of the liquid crystal and induces defects. The surface protection film is not only peeled off, but the same problem occurs due to the friction between the optical films depending on the manufacturing process and the usage method of the consumer.

  In order to sufficiently suppress malfunction of the liquid crystal display device and electrostatic breakdown of the TFT driving element, it has been proposed to impart antistatic properties to an optical film such as a polarizing plate. For example, since a polarizing plate is usually provided with a protective film such as a triacetyl cellulose film on both sides of the polarizer, an antistatic layer is provided on the triacetyl cellulose film used as the protective film of the polarizer. Has been proposed (see Patent Document 1). However, when an antistatic layer is formed on a triacetyl cellulose film, the production process of the protective film increases, which leads to a decrease in yield, which is not preferable.

  On the other hand, it has also been proposed to form an antistatic layer in addition to the pressure-sensitive adhesive layer on a surface protective film applied to an optical film. However, when the antistatic layer is formed on the surface protective film, the production process of the surface protective film is increased in the same manner as described above, which leads to a decrease in yield. In addition, it has been proposed to add an antistatic agent to the pressure-sensitive adhesive layer of a general pressure-sensitive adhesive tape to impart an antistatic effect to the pressure-sensitive adhesive tape itself (see Patent Document 2 and Patent Document 3). Such a pressure-sensitive adhesive tape can be directly prevented from being charged at the site where the peeling charge is generated. However, the adhesive tape has a problem of contaminating the adherend due to bleeding out of the charging portion preventing agent. In particular, since the surface contamination of the optical film becomes a problem, the adhesive tape cannot be applied to a surface protective film for an optical film.

Japanese Patent Laid-Open No. 11-90038 JP-A-8-253755 JP 9-255932 A

  The present invention is an optical film with a surface protective film in which a surface protective film is provided on the surface of the optical film, the amount of peeling charge generated when the surface protective film is peeled from the optical film can be reduced, and the surface protective film An object of the present invention is to provide an optical film with a surface protective film that does not have a problem of contamination on the surface of the optical film after peeling.

  Another object of the present invention is to provide an image display device using the optical film with a surface protective film.

  As a result of intensive studies to solve the above problems, the present inventors have found the following surface protective film and have completed the present invention.

  That is, the present invention provides a surface protection for an optical film for protecting an optical film surface that has been activated by a treatment selected from the group consisting of saponification, corona treatment, UV treatment, electron beam treatment, and plasma treatment. A film having a base film and a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer containing 0.1 to 1% by weight of an ionic antistatic agent relative to the base polymer in the pressure-sensitive adhesive layer; It is related with the surface protection film for optical films whose adhesive force with respect to the optical film of this surface protection film for optical films is 0.01-2N / 50mm.

  When the pressure-sensitive adhesive layer of the surface protective film contains an ionic antistatic agent, the antistatic agent on the surface of the pressure-sensitive adhesive layer is transferred to the surface of the optical film to prevent peeling charge that occurs when the surface protective film is peeled off. , Can prevent problems caused by static electricity. If the amount of the antistatic agent added to the pressure-sensitive adhesive is increased, the antistatic agent bleeds out of the pressure-sensitive adhesive in addition to the initial transfer amount, so that the antistatic effect is improved. However, when the transfer amount (bleed out amount) of the antistatic agent is increased, the surface of the optical film is highly contaminated, resulting in a defect in optical characteristics. In addition, the stickiness varies and decreases depending on the transfer amount of the antistatic agent. On the other hand, when the addition amount of the antistatic agent added to the pressure-sensitive adhesive is small, there is no problem of contamination and the control of the contamination becomes easy, but a sufficient antistatic effect cannot be obtained.

  In the present invention, for protecting the surface of the activated optical film, an antistatic agent is contained in the pressure-sensitive adhesive layer of the surface protective film, and the amount of the antistatic agent added to the pressure-sensitive adhesive layer is small. In addition, an appropriate amount of the antistatic agent can be transferred. As described above, in the present invention, since the transfer amount of the antistatic agent can be efficiently transferred, an antistatic effect can be imparted to the surface of the optical film and the surface contamination of the optical film can be controlled. Further, since the transfer amount of the antistatic agent can be controlled, fluctuations and lowering of adhesiveness can be suppressed.

  The thickness of the pressure-sensitive adhesive layer is preferably 5 μm to 50 μm.

The thickness of the substrate is preferably 10 to 200 μm.

The pressure-sensitive adhesive layer is preferably formed of an acrylic pressure-sensitive adhesive.

The pressure-sensitive adhesive layer preferably contains an epoxy-based crosslinking agent or a polyisocyanate compound crosslinking agent.

When the surface protective film for an optical film is provided on the optical film and then the optical film is peeled off, the amount of the antistatic agent transferred to the surface of the optical film is 0.00001 to 0.06 g / m ² . It is preferable.

  In the surface protective film for optical films, the peel charge amount is preferably less than 2 kV.

It is an example of sectional drawing of the optical film with a surface protection film of this invention.

  In the optical film with a surface protective film of the present invention, the surface protective film 1 is provided on the surface a of the optical film 2 as shown in FIG. The surface protective film 1 has a base film 11 and an adhesive layer 12, and is provided on the surface a of the optical film 2 through the adhesive layer 12. The surface a of the optical film 2 is activated.

  FIG. 1 illustrates the case where protective films 22 and 23 are provided on both sides of a polarizer 21 as the optical film 2. The surface of the protective film 22 becomes the surface a of the optical film 2. In addition, as shown in FIG. 1, the adhesive layer 3 can be provided in the side which does not provide the surface protection film 1 of the optical film 2. FIG.

  As the base film for the surface protective film, those conventionally used for the surface protective film can be used without particular limitation. In general, a film material having isotropic property or near isotropic property is selected from the viewpoints of inspection property and manageability of the optical film by fluoroscopy. Examples of film materials include polyester resins such as polyethylene terephthalate film, cellulose resins, acetate resins, polyether sulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, acrylic resins, and the like. Examples thereof include transparent polymers such as resins. Of these, polyester resins are preferred. The base film can be used as a laminate of one kind or two or more kinds of film materials, and a stretched product of the film can also be used. The thickness of the base film is generally 500 μm or less, preferably 10 to 200 μm.

  As the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer of the surface protective film, any pressure-sensitive adhesive such as acrylic, synthetic rubber, rubber, and silicone can be used, but transparency, weather resistance, heat resistance, etc. From the viewpoint, an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is preferable. The weight average molecular weight of the acrylic polymer is preferably about 300,000 to 2.5 million.

  As a monomer used for the acrylic polymer, various alkyl (meth) acrylates can be used. For example, (meth) acrylic acid alkyl ester (for example, methyl ester, ethyl ester, propyl ester, butyl ester, 2-ethylhexyl ester, isooctyl ester, isononyl ester, isodecyl ester, dodecyl ester, lauryl ester, tridecyl ester , Pentadecyl ester, hexadecyl ester, heptadecyl ester, octadecyl ester, nonadecyl ester, eicosyl ester and the like, which can be used alone or in combination.

  Moreover, as a modifier of the acrylic polymer obtained, together with the (meth) acrylic acid alkyl ester, carboxyl group-containing monomers such as (meth) acrylic acid and itaconic acid; (meth) hydroxyethyl acrylate, (meth) ) Hydroxyl group-containing monomers such as hydroxypropyl acrylate; Amide group-containing monomers such as N-methylolacrylamide; Cyano group-containing monomers such as (meth) acrylonitrile; Epoxy groups such as glycidyl (meth) acrylate Containing monomers; vinyl esters such as vinyl acetate; styrene monomers such as styrene and α-methylstyrene can be used as the copolymerization monomer.

  The polymerization method for the acrylic polymer is not particularly limited, and a known polymerization method such as solution polymerization, emulsion polymerization, suspension polymerization, or UV polymerization can be employed.

  The pressure-sensitive adhesive contains an ionic antistatic agent. As the ionic antistatic agent, cationic (for example, quaternary ammonium salt type, phosphonium salt type, sulfonium salt type, etc.), anionic type (carboxylic acid type, sulfonate type, sulfate type, phosphate type, phosphite type, etc.) And zwitterionic systems (sulfobetaine type, alkylbetaine type, alkylimidazolium betaine type, etc.).

Among these, a cationic type, particularly a quaternary ammonium salt type is preferable. As a quaternary ammonium salt type cationic antistatic agent, for example,
General ^{formula: [(R 1, R 2} , R 3, R 4) -N] + X -
(In the formula, R ¹ , R ² , R ³ and R ⁴ each independently represents an alkyl group having 1 to 18 carbon atoms or a hydrogen atom. However, not all of R ^{1 to} R ⁴ are hydrogen atoms. X represents a base such as a halogen atom).

  The amount of the ionic antistatic agent added to the pressure-sensitive adhesive is preferably less than about 0.1 to 2.5% by weight with respect to the base polymer. More preferably, it is 0.5 to 1% by weight. If it is less than 0.1% by weight, the antistatic effect tends to be insufficient. If the amount is 2.5% by weight or more, the transfer amount increases, and it may be difficult to control the antistatic effect, contamination, and adhesive performance.

  The pressure-sensitive adhesive can contain a crosslinking agent. Examples of the crosslinking agent include polyisocyanate compounds, polyamine compounds, melamine resins, urea resins, and epoxy resins. Furthermore, a tackifier resin, a plasticizer, a filler, an antioxidant, an ultraviolet absorber, a silane coupling agent, and the like can be used as appropriate for the pressure-sensitive adhesive.

  The method for forming the pressure-sensitive adhesive layer is not particularly limited, and is a method in which a pressure-sensitive adhesive is applied to a release liner, dried and then transferred to a base film (transfer method), and the pressure-sensitive adhesive is directly applied to the base film and dried. (Direct copying method) and the like. The thickness (dry film thickness) of the pressure-sensitive adhesive layer is determined according to the required adhesive force. Usually, it is about 1-100 micrometers, Preferably it is 5-50 micrometers.

  In FIG. 1, only the base film 11 and the pressure-sensitive adhesive layer 12 are shown as the surface protective film 1, but the surface protective film 1 has a surface opposite to the surface on which the pressure-sensitive adhesive layer 12 is provided. In addition, the release treatment layer can be provided by a low adhesive material such as silicone treatment, long-chain alkyl treatment, or fluorine treatment.

  As an optical film used for the optical film with a surface protective film of the present invention, those used for forming an image display device such as a liquid crystal display device are used, and the kind thereof is not particularly limited.

  As the optical film, a surface protective film whose surface is in contact with the pressure-sensitive adhesive layer is activated. Examples of the activation treatment include saponification treatment, corona treatment, UV treatment, electron beam treatment, and plasma treatment. As the activation treatment, saponification treatment and corona treatment are preferred.

  For the saponification treatment, an aqueous alkali hydroxide solution such as an aqueous sodium hydroxide solution or an aqueous potassium hydride solution is used. The saponification treatment is performed by passing or immersing the surface of the optical film in an aqueous alkali hydroxide solution. The concentration of the aqueous alkali hydroxide solution is preferably about 2 to 25% by weight. The concentration of the alkali hydroxide aqueous solution is preferably 7 to 15% by weight from the viewpoint of easy control of treatment time and active state. The treatment conditions are preferably about 20 to 80 ° C., more preferably 40 to 70 ° C., for about 5 to 300 seconds, and further preferably for 5 to 240 seconds.

  The corona treatment is not particularly limited, but considering the heat load applied to the surface of the optical film, for example, the treatment of about 0.3 to 20 kW is performed on the optical film conveyed at 2 to 40 m / min. preferable.

  An example of the optical film is a polarizing plate. A polarizing plate having a transparent protective film on one or both sides of a polarizer is generally used. In such a polarizing plate, the activation treatment is performed on the surface of the protective film.

  The polarizer is not particularly limited, and various types can be used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be prepared by, for example, dying polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution such as boric acid or potassium iodide or in a water bath.

  As a material for forming the transparent protective film provided on one side or both sides of the polarizer, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile / styrene copolymer (AS resin) -Based polymer, polycarbonate-based polymer and the like. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Polymer blends and the like are also examples of polymers that form the transparent protective film. The transparent protective film can also be formed as a cured layer of thermosetting or ultraviolet curable resin such as acrylic, urethane, acrylurethane, epoxy, and silicone.

  Moreover, the polymer film described in JP-A-2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain, and (B) a substitution in the side chain And / or a resin composition containing a thermoplastic resin having unsubstituted phenyl and a nitrile group. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used.

  Although the thickness of a protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin film property. In particular, 5 to 200 μm is preferable.

  Moreover, it is preferable that a protective film has as little color as possible. Therefore, Rth = [(nx + ny) / 2−nz] · d (where nx and ny are the main refractive index in the plane of the film, nz is the refractive index in the film thickness direction, and d is the film thickness). A protective film having a retardation in the film thickness direction of −90 nm to +75 nm is preferably used. By using a film having a thickness direction retardation value (Rth) of −90 nm to +75 nm, coloring (optical coloring) of the polarizing plate caused by the protective film can be almost eliminated. The thickness direction retardation (Rth) is more preferably -80 nm to +60 nm, and particularly preferably -70 nm to +45 nm.

  As the protective film, a cellulose polymer such as triacetyl cellulose is preferable from the viewpoints of polarization characteristics and durability. A triacetyl cellulose film is particularly preferable. In addition, when providing a protective film on both sides of a polarizer, the protective film which consists of the same polymer material may be used by the front and back, and the protective film which consists of a different polymer material etc. may be used. The polarizer and the protective film are usually in close contact with each other through an aqueous adhesive or the like. Examples of the water-based adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex, a water-based polyurethane, and a water-based polyester.

  The surface of the transparent protective film to which the polarizer is not adhered may be subjected to a treatment for the purpose of hard coat layer, antireflection treatment, sticking prevention, diffusion or antiglare. When the treatment layer provided on the protective film becomes the polarizing plate surface, the activation treatment is performed on the treatment layer.

  The hard coat treatment is applied for the purpose of preventing scratches on the surface of the polarizing plate. For example, a transparent protective film with a cured film excellent in hardness, sliding properties, etc. by an appropriate ultraviolet curable resin such as acrylic or silicone is used. It can be formed by a method of adding to the surface of the film. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. Further, the sticking prevention treatment is performed for the purpose of preventing adhesion between adjacent layers of other members.

  Anti-glare treatment is applied for the purpose of preventing external light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by sandblasting or embossing. It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a method or a compounding method of transparent fine particles. Examples of the fine particles to be included in the formation of the surface fine concavo-convex structure include conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like having an average particle diameter of 0.5 to 50 μm. In some cases, transparent fine particles such as inorganic fine particles and organic fine particles (including beads) made of a crosslinked or uncrosslinked polymer are used. When forming a surface fine uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The anti-glare layer may also serve as a diffusion layer (such as a visual enlargement function) for diffusing the light transmitted through the polarizing plate to enlarge vision.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the transparent protective film itself, or can be provided separately from the transparent protective film as an optical layer.

  In addition, as an optical film, for example, it is used for forming a liquid crystal display device such as a reflection plate, an anti-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), a visual compensation film, and a brightness enhancement film. And an optical layer that may be formed. These can be used alone as an optical film, or can be laminated on the polarizing plate for practical use and used as one layer or two or more layers.

  In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a polarizing plate is further laminated with a reflecting plate or a semi-transmissive reflecting plate, an elliptical polarizing plate or a circular polarizing plate in which a retardation plate is further laminated on a polarizing plate, a polarizing plate A wide viewing angle polarizing plate in which a visual compensation film is further laminated on a plate, or a polarizing plate in which a luminance enhancement film is further laminated on a polarizing plate is preferable.

  A reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side). Such a light source can be omitted, and the liquid crystal display device can be easily thinned. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one surface of the polarizing plate via a transparent protective layer or the like as necessary.

  Specific examples of the reflective polarizing plate include those in which a reflective layer is formed by attaching a foil or a vapor deposition film made of a reflective metal such as aluminum on one side of a transparent protective film matted as necessary. In addition, the transparent protective film may contain fine particles to form a surface fine concavo-convex structure, and a reflective layer having a fine concavo-convex structure thereon. The reflective layer having the fine concavo-convex structure has an advantage that incident light is diffused by irregular reflection to prevent directivity and glaring appearance and to suppress unevenness in brightness and darkness. Moreover, the protective film containing fine particles also has an advantage that incident light and its reflected light are diffused when passing through it and light and dark unevenness can be further suppressed. The reflective layer of the fine concavo-convex structure reflecting the surface fine concavo-convex structure of the transparent protective film is formed by, for example, applying metal to the surface of the transparent protective layer by an appropriate method such as a vacuum deposition method, an ion plating method, a sputtering method, or a plating method. It can be performed by a method of attaching directly to the screen.

  Instead of the method of directly applying the reflecting plate to the transparent protective film of the polarizing plate, the reflecting plate can be used as a reflecting sheet provided with a reflecting layer on an appropriate film according to the transparent film. Since the reflective layer is usually made of metal, the usage form in which the reflective surface is covered with a transparent protective film, a polarizing plate or the like is used to prevent the reflectance from being lowered due to oxidation, and thus to maintain the initial reflectance for a long time. In addition, it is more preferable to avoid a separate attachment of the protective layer.

  The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell, and displays an image by reflecting incident light from the viewing side (display side) when a liquid crystal display device is used in a relatively bright atmosphere. In a relatively dark atmosphere, a liquid crystal display device of a type that displays an image using a built-in power source such as a backlight built in the back side of the transflective polarizing plate can be formed. In other words, the transflective polarizing plate can be used to form liquid crystal display devices that can save energy when using a light source such as a backlight in a bright atmosphere and can be used with a built-in power supply even in a relatively dark atmosphere. It is.

  An elliptically polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on a polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light to elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called quarter-wave plate (also referred to as a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also referred to as a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.

  The elliptically polarizing plate is effectively used for black and white display without the above color by compensating (preventing) the coloration (blue or yellow) generated by the birefringence of the liquid crystal layer of the super twist nematic (STN) type liquid crystal display device. It is done. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has an antireflection function.

  Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm.

  Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose polymer, norbornene resin, or binary, ternary copolymers, graft copolymers, Examples include blends. These polymer materials become an oriented product (stretched film) by stretching or the like.

  Examples of the liquid crystal polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. . Specific examples of the main chain type liquid crystal polymer include a nematic alignment polyester liquid crystal polymer, a discotic polymer, and a cholesteric polymer having a structure in which a mesogen group is bonded at a spacer portion that imparts flexibility. Specific examples of the side chain type liquid crystal polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment-providing para-substitution through a spacer portion composed of conjugated atomic groups as side chains. Examples thereof include those having a mesogenic part composed of a cyclic compound unit. These liquid crystal polymers are prepared by, for example, applying a solution of a liquid crystalline polymer on an alignment treatment surface such as a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or an oblique deposition of silicon oxide. This is done by developing and heat treatment.

  The retardation plate may have an appropriate retardation according to the purpose of use, such as for the purpose of compensating for coloring, vision, etc. due to birefringence of various wave plates and liquid crystal layers, and may be two or more types. It may be one in which retardation plates are stacked and optical characteristics such as retardation are controlled.

  The elliptical polarizing plate and the reflective elliptical polarizing plate are obtained by laminating a polarizing plate or a reflective polarizing plate and a retardation plate in an appropriate combination. Such an elliptically polarizing plate or the like can also be formed by sequentially laminating them sequentially in the manufacturing process of the liquid crystal display device so as to be a combination of a (reflective) polarizing plate and a retardation plate. An optical film such as a polarizing plate has an advantage that it can improve the production efficiency of a liquid crystal display device and the like because of excellent quality stability and lamination workability.

  The visual compensation film is a film for widening the viewing angle so that the image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen. Examples of such a visual compensation phase difference plate include a phase difference plate, an alignment film such as a liquid crystal polymer, and a film in which an alignment layer such as a liquid crystal polymer is supported on a transparent substrate. A normal retardation plate uses a birefringent polymer film that is uniaxially stretched in the plane direction, whereas a retardation plate used as a visual compensation film is biaxially stretched in the plane direction. Birefringent polymer film, biaxially stretched film such as polymer with birefringence with a controlled refractive index in the thickness direction that is uniaxially stretched in the plane direction and stretched in the thickness direction, etc. Used. Examples of the inclined alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, and a film obtained by obliquely aligning a liquid crystal polymer. can give. The raw material polymer for the phase difference plate is the same as the polymer described in the previous phase difference plate, preventing coloration due to a change in the viewing angle based on the phase difference by the liquid crystal cell and expanding the viewing angle for good visual recognition. An appropriate one for the purpose can be used.

  In addition, from the viewpoint of achieving a wide viewing angle with good visibility, an optical compensation position in which an alignment layer of a liquid crystal polymer, particularly an optically anisotropic layer composed of a tilted alignment layer of a discotic liquid crystal polymer, is supported by a triacetyl cellulose film. A phase difference plate can be preferably used.

  A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer. That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and accordingly, the amount of light that can be used for liquid crystal image display or the like is reduced and the image becomes dark. The brightness enhancement film reflects light that has a polarization direction that is absorbed by the polarizer without being incident on the polarizer, and is reflected by the brightness enhancement film, and then inverted through a reflective layer or the like provided behind the brightness enhancement film. The brightness enhancement film transmits only the polarized light in which the polarization direction of the light reflected and inverted between the two is allowed to pass through the polarizer. Since the light is supplied to the polarizer, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

  A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The polarized light reflected by the brightness enhancement film is directed to the reflective layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough and simultaneously cancels the polarized state and becomes a non-polarized state. That is, the light in the natural light state is directed toward the reflection layer or the like, reflected through the reflection layer or the like, and again passes through the diffusion plate and reenters the brightness enhancement film. In this way, by providing a diffuser plate that returns polarized light to the original natural light between the brightness enhancement film and the reflective layer, the brightness of the display screen is maintained, and at the same time, the brightness of the display screen is reduced and uniform. Can provide a bright screen. By providing such a diffuser plate, it is considered that the first incident light has a moderate increase in the number of repetitions of reflection, and in combination with the diffusion function of the diffuser plate, a uniform bright display screen can be provided.

  The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropies. Such as an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer supported on a film substrate, which reflects either left-handed or right-handed circularly polarized light and transmits other light. Appropriate things, such as a thing, can be used.

  Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is incident on the polarizing plate with the polarization axis aligned as it is, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light such as a cholesteric liquid crystal layer, it can be incident on a polarizer as it is, but from the point of suppressing absorption loss, the circularly polarized light is converted into linearly polarized light through a retardation plate. It is preferably incident on the polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.

  A retardation plate that functions as a quarter-wave plate at a wide wavelength in the visible light region or the like exhibits, for example, a retardation plate that functions as a quarter-wave plate for light-colored light having a wavelength of 550 nm and other retardation characteristics. It can be obtained by a method in which a phase difference layer, for example, a phase difference layer that functions as a half-wave plate is superimposed. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.

  In addition, a cholesteric liquid crystal layer having a reflection structure that reflects circularly polarized light in a wide wavelength range such as a visible light range can be obtained by combining two or more layers with different reflection wavelengths to form an overlapping structure. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

  Further, the polarizing plate may be formed by laminating a polarizing plate and two or more optical layers as in the above-described polarization separation type polarizing plate. Therefore, a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above-described reflective polarizing plate or semi-transmissive polarizing plate and a retardation plate are combined may be used.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When bonding the polarizing plate and the other optical layer, their optical axes can be set at an appropriate arrangement angle in accordance with the target retardation characteristics.

  The above-mentioned optical film such as a polarizing plate can be provided with an adhesive layer for adhering to other members such as a liquid crystal cell. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately selected. Can be used. In particular, those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance, heat resistance and the like can be preferably used.

  In addition to the above, in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical properties and liquid crystal cell warpage due to differences in thermal expansion, etc., as well as formability of liquid crystal display devices with high quality and excellent durability An adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.

  The adhesive layer is, for example, natural or synthetic resins, in particular, tackifier resins, fillers or pigments made of glass fibers, glass beads, metal powders, other inorganic powders, colorants, antioxidants, etc. It may contain an additive to be added to the adhesive layer. Moreover, the adhesion layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.

  The attachment of the adhesive layer to the optical film can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a suitable solvent alone or a mixture such as toluene and ethyl acetate is prepared. A method in which it is directly attached on a polarizing plate or an optical film by an appropriate development method such as a casting method or a coating method, or an adhesive layer is formed on a separator according to the above, and this is applied to a polarizing plate or an optical film. The method of moving up is mentioned.

  The pressure-sensitive adhesive layer can be provided on the optical film as a superimposed layer of different compositions or types. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 500 μm, preferably 5 to 200 μm, particularly preferably 10 to 100 μm.

  On the exposed surface of the adhesive layer, a separator is temporarily attached and covered for the purpose of preventing contamination until it is put to practical use. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminate thereof, and the like, silicone type or Appropriate conventional ones such as those coated with an appropriate release agent such as long-chain alkyl, fluorine-based, or molybdenum sulfide can be used.

  In the present invention, the above-described optical film or the like, or each layer such as an adhesive layer, may be an ultraviolet absorber such as a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, or a nickel complex compound. It may be a material having ultraviolet absorption ability by a method such as a method of treating with.

  The optical film of the present invention can be preferably used for forming various image display devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by assembling components such as a liquid crystal cell, an optical film, and an illumination system as necessary, and incorporating a drive circuit according to the conventional method. As the liquid crystal cell, an arbitrary type such as an arbitrary type such as a TN type, an STN type, or a π type can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which an optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the optical film according to the present invention can be installed on one side or both sides of the liquid crystal cell. When optical films are provided on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  Next, an organic electroluminescence device (organic EL display device) will be described. The optical film (polarizing plate or the like) of the present invention can also be applied to an organic EL display device. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminate of such a light-emitting layer and an electron injection layer composed of a perylene derivative or the like, or a laminate of these hole injection layer, light-emitting layer, and electron injection layer is known. It has been.

  In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the phosphor material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

  In an organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent, and a transparent electrode usually formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. It is used as. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode While providing a polarizing plate on the side, a retardation plate can be provided between the transparent electrode and the polarizing plate.

  Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation plate with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizing plate and the retardation plate to π / 4. .

  That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light becomes generally elliptically polarized light by the phase difference plate, but becomes circularly polarized light particularly when the phase difference plate is a quarter wavelength plate and the angle formed by the polarization direction of the polarizing plate and the phase difference plate is π / 4. .

  This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again on the retardation plate. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, all the parts and% in each example are based on weight.

Comparative Example 1
(Production of optical film)
A polyvinyl alcohol film having a thickness of 80 μm was stretched 5 times in an aqueous iodine solution (concentration: 0.3% by weight) at 35 ° C. and then dried at 50 ° C. for 4 minutes to obtain a polarizer. A triacetyl cellulose film having a thickness of 80 μm was adhered to one side of the polarizer using a polyvinyl alcohol-based adhesive. On the other hand, on the other side of the polarizer, a triacetyl cellulose film having a thickness of 80 μm formed with an antiglare layer (thickness 10 μm) is adhered using a polyvinyl alcohol-based adhesive, and the thickness is 100 μm. A polarizing plate was prepared. The antiglare treatment layer is obtained by adding 10 parts of silica particles having an average particle diameter of 1.8 μm to an ultraviolet curable resin composition comprising 100 parts of an ultraviolet curable urethane acrylate monomer and 3 parts of a benzophenone photopolymerization initiator, and further adding a viscosity Formed by adding ethyl acetate as a solvent for adjustment to adjust the solids concentration to 50% and mixing with a high-speed stirrer, coating, volatilizing the solvent, and then irradiating with ultraviolet rays and curing. did. Further, an acrylic pressure-sensitive adhesive was applied to the opposite side of the obtained polarizing plate to the antiglare layer and dried to form a pressure-sensitive adhesive layer having a thickness of 25 μm to obtain a polarizing plate with a pressure-sensitive adhesive layer.

(Production of surface protective film)
<Preparation of adhesive> A 25% ethyl acetate solution of acrylic polymer (weight ratio: 68/29/3, weight average molecular weight 400,000) of 2-ethylhexyl acrylate, methyl methacrylate and 2-hydroxyethyl acrylate was prepared. In terms of solid content, 3 parts by weight of trimethylolpropane tolylene diisocyanate was added to and mixed with 100 parts by weight of the acrylic polymer to prepare an acrylic pressure-sensitive adhesive composition.

  Apply the above acrylic pressure-sensitive adhesive composition to one side of a 38 μm thick polyethylene terephthalate film so that the thickness after drying is 15 μm, and dry at 120 ° C. for 2 minutes to form a pressure-sensitive adhesive layer to protect the surface. A film was obtained.

(Optical film with surface protective film)
The pressure-sensitive adhesive layer side of the surface protective film was attached to the antiglare treatment layer side of the polarizing plate to produce an optical film with a surface protective film.

Comparative Example 2
Comparative Example 1 except that, in Comparative Example 1 (production of surface protective film), a pressure-sensitive adhesive was prepared by adding 1% by weight of stearyltrimethylammonium chloride as an ionic antistatic agent to the acrylic polymer in the pressure-sensitive adhesive. In the same manner as in Example 1, a surface protective film was produced. Moreover, the optical film with a surface protective film was produced like the comparative example 1 except having used the said surface protective film.

Comparative Example 3
In Comparative Example 1 (production of surface protective film), except that stearyltrimethylammonium chloride as an ionic antistatic agent was added in an amount of 2.5% by weight to the acrylic polymer in the pressure-sensitive adhesive. A surface protective film was produced in the same manner as in Comparative Example 1. Moreover, the optical film with a surface protective film was produced like the comparative example 1 except having used the said surface protective film.

Example 1
The antiglare treatment layer side of the polarizing plate prepared in Comparative Example 1 was saponified by dipping with a 10% aqueous sodium hydroxide solution at 65 ° C. for 30 seconds. The surface protective film used in Comparative Example 2 was used. The pressure-sensitive adhesive layer side of the surface protective film was attached to the antiglare treatment layer side of the polarizing plate to produce an optical film with a surface protective film.

Example 2
The antiglare treatment layer side of the polarizing plate prepared in Comparative Example 1 was saponified by dipping with a 10% aqueous sodium hydroxide solution at 65 ° C. for 120 seconds. The surface protective film used in Comparative Example 2 was used. The pressure-sensitive adhesive layer side of the surface protective film was attached to the antiglare treatment layer side of the polarizing plate to produce an optical film with a surface protective film.

Example 3
The antiglare treatment layer side of the polarizing plate prepared in Comparative Example 1 was subjected to corona treatment at a line speed of 5 m / min and 0.7 kW. The surface protective film used in Comparative Example 2 was used. The pressure-sensitive adhesive layer side of the surface protective film was attached to the antiglare treatment layer side of the polarizing plate to produce an optical film with a surface protective film.

Example 4
The antiglare treatment layer side of the polarizing plate prepared in Comparative Example 1 was subjected to corona treatment at a line speed of 5 m / min and 1.4 kW. The surface protective film used in Comparative Example 2 was used. The pressure-sensitive adhesive layer side of the surface protective film was attached to the antiglare treatment layer side of the polarizing plate to produce an optical film with a surface protective film.

  The following evaluation was performed about the optical film with a surface protective film obtained by the Example and the comparative example. After the production, the sample was conditioned for 10 days in an atmosphere of 23 ° C./50% RH. The results are shown in Table 1.

[Peeling charge measurement]
The sample was cut out to 70 mm × 100 mm and bonded to a non-alkali glass (0.7 mm thickness) plate of the same size, and then the surface protective film was peeled off at a speed of 10 m / min in an atmosphere of 23 ° C./50% RH. . At that time, the maximum value of the peeling charge generated at the center of the sample was defined as the peeling charge amount (kV). The peel charge amount was KSD-0103 manufactured by Kasuga Denki, and the distance from the measurement point was 10 cm. Evaluation is based on the following criteria.
A: Less than 0.5 kV.
○: 0.5 to less than 2 kV.
Δ: Less than 2 to 2.5 kV.
X: 2.5 kV or more.

[Antistatic agent transfer amount]
The surface protective film was peeled off from the sample (70 mm × 70 mm) with tweezers, the surface side to which the protective film was bonded was washed away with ultrapure water, and the recovered liquid was used as an analysis sample. The sample was subjected to ion chromatography (Dionex: DX-500, column: Dionex IonPacAG12A + AS12A, eluent: 2.7 mm-Na ₂ CO ₃ /0.3 mm-NaHCO ₃ ) from the chloride ion concentration contained in the sample. The amount of the antistatic agent transferred to the polarizing plate was quantified. The measurement was performed at n = 2, and the average value was defined as the transfer amount (g / m ² ).

[Adhesion test]
A sample was cut to a width of 50 mm. The polarizing plate side (adhesive layer side) was fixed, and the surface protective film was peeled from the polarizing plate using a tensile tester at a pulling speed of 300 mm / min and a pulling angle of 180 °. The force required for peeling was defined as adhesive strength (N / 50 mm). The adhesive strength is preferably controlled in the range of 0.01 to 2 N / 50 mm, and more preferably in the range of 0.05 to 1 N / 50 mm in terms of surface protection function and peelability.

  As shown in Table 1, as shown in the examples, the amount of the antistatic agent contained in the pressure-sensitive adhesive layer of the surface protective film can be controlled by activating the polarizing plate surface by saponification treatment or corona treatment. Therefore, peeling charge can be sufficiently reduced with a smaller addition amount of the antistatic agent contained in the pressure-sensitive adhesive layer. Moreover, it can be satisfied also about surface contamination property and adhesiveness. On the other hand, when the surface of the polarizing plate is not subjected to activation treatment as in Comparative Example 2 and the amount of antistatic agent contained in the pressure-sensitive adhesive layer of the surface protective film is small as in the example, the peel charge amount increases. In addition, as in Comparative Example 3, if the surface of the polarizing plate is not subjected to an activation treatment and the amount of antistatic agent contained in the pressure-sensitive adhesive layer of the surface protective film is increased, the amount of peeling charge is reduced, but the transfer of the antistatic agent is reduced. The amount increases and the pollution problem cannot be controlled. It is also difficult to control the adhesiveness.

DESCRIPTION OF SYMBOLS 1 Surface protective film 11 Base film 12 Adhesive layer of surface protective film 2 Polarizing plate (optical film)
DESCRIPTION OF SYMBOLS 21 Polarizer 22 Protective film of polarizer 23 Protective film of polarizer 3 Adhesive layer of optical film

Claims (7)

A surface protective film for an optical film for protecting an optical film surface subjected to activation treatment by a treatment selected from the group consisting of saponification treatment, corona treatment, UV treatment, electron beam treatment, and plasma treatment,
Having a base film and an adhesive layer,
The pressure-sensitive adhesive layer contains 0.1 to 1% by weight of an ionic antistatic agent with respect to the base polymer in the pressure-sensitive adhesive layer,
The surface protection film for optical films whose adhesive force with respect to this optical film of this surface protection film for optical films is 0.01-2N / 50mm.   The surface protection film for optical films according to claim 1 whose thickness of said adhesive layer is 5 micrometers-50 micrometers. The surface protection film for optical films according to claim 1 or 2 whose thickness of said substrate is 10-200 micrometers. The surface protective film for optical films according to claim 1, wherein the pressure-sensitive adhesive layer is formed of an acrylic pressure-sensitive adhesive. The surface protective film for optical films according to claim 1, wherein the pressure-sensitive adhesive layer contains an epoxy-based crosslinking agent or a polyisocyanate compound crosslinking agent. When the surface protective film for an optical film is provided on the optical film and then the optical film is peeled off, the amount of the antistatic agent transferred to the surface of the optical film is 0.00001 to 0.06 g / m ² . The surface protective film for optical films of any one of Claims 1-5.   The surface protective film for optical films according to any one of claims 1 to 6, wherein the peel charge amount is less than 2 kV.