JP2006284881A - Polarizer protective film, polarizing plate, and image display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizer protective film with high productivity, the film excellent in mechanical strength which solves problems of being fragile and easily broken, and having high heat resistance and optical transparency and excellent moisture resistance, to provide a polarizing plate having less defect in the appearance using the above polarizer protective film and a polarizer made of polyvinyl alcohol resin, and to provide a high definition image display apparatus with high productivity using the above polarizing plate. <P>SOLUTION: The polarizer protective film essentially comprises a (meth)acrylic resin having ≥100°C Tg, and shows ≤1.0 in-plane retardation Δnd, ≤3.0 retardation Rth in the thickness direction, and ≤65 g/m<SP>2</SP>24 hours of moisture permeability. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polarizer protective film, a polarizing plate using the same, and an image display device such as a liquid crystal display device, an organic EL display device, and a PDP including at least one polarizing plate.

  In the liquid crystal display device, it is indispensable to dispose polarizing plates on both sides of the glass substrate on which the liquid crystal panel surface is formed because of the image forming method. In general, a polarizing plate is obtained by attaching a polarizer protective film using triacetyl cellulose or the like to both surfaces of a polarizer made of a dichroic material such as a polyvinyl alcohol film and iodine with a polyvinyl alcohol adhesive. Things are used.

  However, triacetyl cellulose does not have sufficient heat and heat resistance, and when a polarizing plate using a triacetyl cellulose film as a polarizer protective film is used at high temperature or high humidity, the performance of the polarizing plate such as the degree of polarization and the hue deteriorates. There is a drawback. In addition, the triacetyl cellulose film produces a phase difference with respect to incident light in an oblique direction. Such a phase difference significantly affects viewing angle characteristics as the size of liquid crystal displays increases in recent years.

  As a resin material excellent in heat resistance and optical transparency, a (meth) acrylic resin such as polymethyl methacrylate is well known. However, the (meth) acrylic resin is brittle and easily broken, and has problems such as transportability such as breakage during film transport and poor productivity. Moreover, (meth) acrylic-type resin also has the problem that it is inferior to moisture resistance. For this reason, it was difficult to use the (meth) acrylic resin as it is for the polarizer protective film.

In order to solve the above problems, a composition comprising an acrylic resin (A) and a toughness improver (B) (preferably an impact-resistant acrylic rubber-methyl methacrylate graft copolymer or butyl-modified acetylcellulose). A polarizer protective film made of a material has been proposed (see Patent Document 1). However, in order to improve the mechanical strength, the toughness improver (B) is used in a relatively large amount (acrylic resin (A) / toughness improver (B) by weight ratio = 60 to 90/40 to 10 ), The acrylic resin (A) has a problem that it becomes a polarizer protective film that cannot sufficiently reflect the high heat resistance and high transparency inherently possessed by the acrylic resin (A). Furthermore, there is a problem that the moisture resistance is very inferior (moisture permeability according to JIS-Z-0208 is 130 g / m ² · 24 hr or more).
Japanese Patent Laid-Open No. 5-119217

  The present invention has been made in order to solve the above-described conventional problems. The object of the present invention is to solve the problem of (1) being brittle and easy to break, having excellent mechanical strength, heat resistance, and optical properties. Providing a polarizer protective film with high optical transparency and excellent moisture resistance, and (2) using such a polarizer protective film and a polarizer formed from a polyvinyl alcohol-based resin. It is to provide a polarizing plate with few appearance defects with high productivity, and (3) to provide a high-quality image display device using such a polarizing plate with high productivity.

The polarizer protective film of the present invention is a polarizer protective film containing a (meth) acrylic resin having a Tg of 100 ° C. or higher as a main component, an in-plane retardation Δnd of 1.0 or less, and a thickness direction retardation Rth. Is 3.0 or less, and the moisture permeability is 65 g / m ² · 24 hr or less.

  According to another aspect of the present invention, a polarizing plate is provided. The polarizing plate of the present invention is a polarizing plate comprising a polarizer formed from a polyvinyl alcohol-based resin and the polarizer protective film of the present invention, and the polarizer protects the polarizer via an adhesive layer. It is adhered to the film.

  In a preferred embodiment, the adhesive layer is a layer formed from a polyvinyl alcohol-based adhesive. In preferable embodiment, it has an adhesive layer as at least one of outermost layers.

  According to another aspect of the present invention, an image display device is provided. The image display device of the present invention includes at least one polarizing plate of the present invention.

  According to the present invention, a polarizer protective film having excellent mechanical strength, high heat resistance, high optical transparency, and excellent moisture resistance is solved by solving the problem of being brittle and easily broken. Can be provided well. Moreover, the polarizing plate using such a polarizer protective film and the polarizer formed from a polyvinyl alcohol-type resin with few external appearance faults can be provided with sufficient productivity. Furthermore, a high-quality image display device using such a polarizing plate can be provided with high productivity.

  Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.

[Polarizer protective film]
The polarizer protective film of the present invention contains a (meth) acrylic resin having a Tg (glass transition temperature) of 100 ° C. or higher as a main component. The Tg of this (meth) acrylic resin is preferably 105 ° C. or higher, more preferably 110 ° C. or higher. By including a (meth) acrylic resin having a Tg (glass transition temperature) of 100 ° C. or higher as a main component, for example, it is excellent in durability when finally incorporated into a polarizing plate.

  The (meth) acrylic resin is not particularly limited as long as it is a (meth) acrylic resin having a Tg of 100 ° C. or higher. For example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., Japanese Patent Application Laid-Open No. 2004-70296. (Meth) acrylic resins having a ring structure in the molecule described in the publication, and high Tg (meth) acrylic resins obtained by intramolecular crosslinking or intramolecular cyclization reactions.

  The (meth) acrylic resin preferably has high light transmittance, low in-plane retardation Δnd and low thickness direction retardation Rth.

  Content of the said (meth) acrylic-type resin in the polarizer protective film of this invention becomes like this. Preferably it is 50 to 99 weight%, More preferably, it is 60 to 98 weight%, More preferably, it is 70 to 97 weight%. When the content of the (meth) acrylic resin in the polarizer protective film of the present invention is less than 50% by weight, the high heat resistance and high transparency inherent in the (meth) acrylic resin cannot be sufficiently reflected. If it exceeds 99% by weight, the moisture resistance and mechanical strength may be inferior.

One of the polarizer protective films of the present invention is a polarizer protective film containing a (meth) acrylic resin having a Tg of 100 ° C. or higher as a main component, an in-plane retardation Δnd of 1.0 or less, and a thickness direction. The phase difference Rth is 3.0 or less, and the moisture permeability is 65 g / m ² · 24 hr or less. The three characteristics of in-plane retardation Δnd, thickness direction retardation Rth, and moisture permeability have all the above ranges, thereby eliminating the problem of being brittle and easily cracked, and having excellent mechanical strength and heat resistance. Can provide a polarizer protective film with high productivity and optical transparency and excellent moisture resistance with high productivity.

The in-plane retardation Δnd is preferably 0.9 or less, more preferably 0.8 or less. When the in-plane retardation Δnd exceeds 1.0, the effects of the present invention, particularly, excellent optical characteristics may not be exhibited.
The thickness direction retardation Rth is preferably 2.7 or less, more preferably 2.5 or less. When the thickness direction retardation Rth exceeds 3.0, the effects of the present invention, in particular, excellent optical characteristics may not be exhibited.

The moisture permeability is preferably from ^62g / m 2 · 24hr or less, and more preferably not more than ^60g / m 2 · 24hr. When the moisture permeability exceeds 65 g / m ² · 24 hr, the effects of the present invention, particularly excellent moisture resistance, may not be exhibited.

The polarizer protective film of the present invention also has excellent mechanical strength. Tensile strength, in the MD direction, preferably 65N / mm ² or more, more preferably 70N / mm ² or more, more preferably 75N / mm ² or more, particularly preferably 80 N / mm ² or more, in the TD direction, preferably the 45N / mm ² or more, more preferably 50 N / mm ² or more, more preferably 55N / mm ² or more, and particularly preferably 60N / mm ² or more. The tensile elongation is preferably 6.5% or more, more preferably 7.0% or more, further preferably 7.5% or more, particularly preferably 8.0% or more in the MD direction, and preferably in the TD direction. Is 5.0% or more, more preferably 5.5% or more, still more preferably 6.0% or more, and particularly preferably 6.5% or more. When the tensile strength or tensile elongation is out of the above range, the effects of the present invention, in particular, excellent mechanical strength may not be exhibited.

  In the polarizer protective film of the present invention, the haze representing optical transparency is preferably 5% or less, more preferably 3% or less, still more preferably 1.5% or less, and particularly preferably 1% or less. When the haze is 5% or less, it is possible to visually give a good clear feeling to the film. When the haze is 1.5% or less, even when used as a lighting member such as a window, the visibility and the lighting performance are improved. Since both can be obtained, and even when used as a front plate of a display device, the display contents can be visually recognized well, and thus the industrial utility value is high.

The polarizer protective film of the present invention is a polarizer protective film containing a (meth) acrylic resin having a Tg of 100 ° C. or higher as a main component as described above, and an in-plane retardation Δnd is 1.0 or less. The thickness direction retardation Rth is 3.0 or less, the moisture permeability is 65 g / m ² · 24 hr or less, and as long as it has such a characteristic range, what are the other components in the polarizer protective film? However, if the composition contains 0.1 to 10 parts by weight of a styrene resin having a styrene content of 20 to 40% by weight with respect to 100 parts by weight of the (meth) acrylic resin, Characteristics can be easily expressed.

  That is, a preferred embodiment of the polarizer protective film of the present invention is a polarizer protective film containing a (meth) acrylic resin having a Tg of 100 ° C. or more as a main component, and the amount of the (meth) acrylic resin is 100 parts by weight. On the other hand, 0.1-10 weight part of styrene resin whose styrene content rate is 20-40 weight% is included.

  The content of the styrenic resin with respect to 100 parts by weight of the (meth) acrylic resin is preferably 1 to 9 parts by weight, more preferably 2 to 8 parts by weight, and even more preferably 3 to 7 parts by weight. When the content of the styrene resin relative to 100 parts by weight of the (meth) acrylic resin is less than 0.1 part by weight, the effects of the present invention, particularly excellent moisture resistance and excellent mechanical strength may not be exhibited. is there. When the content of the styrene resin relative to 100 parts by weight of the (meth) acrylic resin exceeds 10 parts by weight, the high heat resistance and high transparency inherent in the (meth) acrylic resin may not be sufficiently reflected. In particular, it may adversely affect optical transparency such as scattering visible light, and may impair the properties required as a polarizer protective film.

  The styrene resin is not particularly limited as long as the styrene content is 20 to 40% by weight. The styrene content is preferably 25 to 35% by weight. When the styrene content is within the above range, optical transparency is not impaired without scattering visible light.

  Examples of the styrene resin include at least one selected from the group consisting of a styrene elastomer, a styrene-butadiene rubber, an acrylonitrile-butylene-styrene resin, and an acrylonitrile-styrene resin.

  Examples of the styrene elastomer include styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer (SEBS), and styrene-ethylene-propylene-styrene block copolymer (SEPS). Styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), styrene-propylene-styrene block copolymer (SPS), and the like. As commercially available products, for example, Tuftec H1041, Tuftec H1051, Tuftec H1053, Tuftec H1062 manufactured by Asahi Kasei Chemicals; Septon 2004, Septon 2006, Septon 2007, Septon 2063, Septon 1001, Septon 4033, Septon 4055, Septon 4077, septon 8004, septon 8006, septon 8007L;

  Examples of the styrene-butadiene rubber include Nipol 1006 and Nipol NS310S manufactured by Nippon Zeon.

  Examples of the acrylonitrile-butylene-styrene resin include Techno ABS 810 and 830 manufactured by Techno Polymer Co., Ltd.

  Examples of the acrylonitrile-styrene resin include Sanrex manufactured by Techno Polymer Co., Ltd. and Stylac AS manufactured by Asahi Kasei Chemicals Co., Ltd.

  When the styrene resin is used, the blend of the styrene resin to the (meth) acrylic resin is directly added or the master batch method is used when the polarizer protective film of the present invention is formed by extrusion molding. It is preferable to perform conventional biaxial kneading. As a kneading method, it is preferable to perform kneading by using a TEM manufactured by Toshiba Machine Co., Ltd., preferably by setting the temperature so that the resin temperature is in the range of 230 to 270 ° C. If the temperature rises too much, decomposition of the (meth) acrylic resin may easily proceed. When the polarizer protective film of the present invention is molded by cast molding (molding by casting), it is preferable to dissolve and blend at the time of preparing the cast solution. Moreover, it is preferable to heat as needed.

  The thickness of the polarizer protective film of the present invention is preferably 20 to 200 μm, more preferably 30 to 180 μm, and still more preferably 40 to 140 μm. When the thickness of the polarizer protective film is 20 μm or more, it has appropriate strength and rigidity, and handling properties are good during secondary processing such as laminating and printing. Further, the phase difference caused by the stress at the time of take-up can be easily controlled, and the film can be manufactured stably and easily. When the thickness of the polarizer protective film is 200 μm or less, film winding becomes easy, and line speed, productivity, and controllability become easy.

  The polarizer protective film of the present invention may be produced by any method, but the resin composition forming the film is extruded (melt extrusion method such as T-die method or inflation method), cast molding ( A melt casting method, etc.) and a method of producing by calendering are preferred.

  Extrusion molding does not require drying and scattering of the solvent in the adhesive used during processing, such as the organic solvent in the adhesive for dry lamination, as in the case of the dry lamination method. Excellent in productivity. Specifically, there can be exemplified a method of forming a film by supplying a resin composition as a raw material to an extruder connected to a T-die, and after melt-kneading, extruding, cooling with water and taking it out. The screw type of the extruder may be uniaxial or biaxial, and an additive such as a plasticizer or an antioxidant may be added.

  The extrusion molding temperature can be appropriately set, but when the glass transition temperature of the resin composition as a raw material is Tg (° C.), (Tg + 80) ° C. to (Tg + 180) ° C. is preferable, and (Tg + 100) ° C. to (Tg + 150) ° C. More preferred. If the extrusion molding temperature is too low, the resin does not have fluidity and may not be molded. If the extrusion molding temperature is too high, the resin viscosity will be low, and there may be a problem in production stability such as uneven thickness of the molded product.

  In the resin composition forming the film, in addition to the (meth) acrylic resin contained as a main component, preferably a styrene resin preferably contained, a general compounding agent such as a stabilizer, a lubricant, and a processing aid. , Plasticizers, impact resistance aids, phase difference reducing agents, ultraviolet absorbers, matting agents, antibacterial agents, fungicides, and the like may be included.

  As the optical characteristics of the polarizer base material, the magnitude of the retardation in the front and thickness directions becomes a problem. Therefore, it is preferable that the resin composition forming the film contains a retardation reducing agent. As the retardation reducing agent, for example, styrene-containing polymers such as acrylonitrile-styrene block copolymer and acrylonitrile-styrene block copolymer copolymer are preferable. The addition amount of the retardation reducing agent is preferably 30% by weight or less, more preferably 25% by weight or less, and further preferably 20% by weight or less with respect to the (meth) acrylic resin. When added exceeding this range, visible light is scattered or transparency is impaired, so that the properties as a polarizer protective film may be lacking.

  In view of protecting the polarizer substrate and the liquid crystal panel, the resin composition forming the film preferably contains an ultraviolet absorber in order to impart weather resistance. The melting point of the ultraviolet absorber is preferably 110 ° C. or higher, and more preferably 120 ° C. or higher. When the melting point of the ultraviolet absorber is 130 ° C. or higher, there is little volatilization at the time of heat-melting processing, and roll contamination during film production is difficult to occur. The type of the UV absorber is not particularly limited, but a benzotriazole UV absorber having a molecular weight of 400 or more and a triazine UV absorber having a molecular weight of 400 or more are particularly preferable. Examples of commercially available products include “Tinubin 1577” (manufactured by Ciba Specialty Chemicals), “Adeka Stub LA-31” (manufactured by Asahi Denka Kogyo Co., Ltd.), and the like.

  The polarizer protective film of this invention can be laminated | stacked and used for another base material. For example, it can be laminated by multilayer extrusion molding including an adhesive resin layer or multilayer inflation molding on a substrate such as glass, a polyolefin resin, an ethylene vinylidene copolymer serving as a high barrier layer, or polyester. If the heat-fusibility is high, the adhesive layer may be omitted.

  The polarizer protective film of the present invention is not only used for protecting the polarizer, but also, for example, a building lighting member such as a window or a carport roof material, a vehicle lighting member such as a window, an agricultural lighting member such as a greenhouse, and an illumination. It can be used by being laminated on a member, a display member such as a front filter, etc., and a housing of home appliances, vehicle interior members, interior building materials, wallpaper, It can also be used by laminating on decorative panels, entrance doors, window frames, baseboards, and the like.

〔Polarizer〕
The polarizing plate of the present invention is a polarizing plate comprising a polarizer formed from a polyvinyl alcohol-based resin and the polarizer protective film of the present invention, and the polarizer protects the polarizer via an adhesive layer. It is adhered to the film.

  As the polarizer formed from the polyvinyl alcohol-based resin, one obtained by dyeing a polyvinyl alcohol-based resin film with a dichroic substance (typically iodine, a dichroic dye) and uniaxially stretching is used. The polymerization degree of the polyvinyl alcohol resin constituting the polyvinyl alcohol resin film is preferably 100 to 5000, and more preferably 1400 to 4000. The polyvinyl alcohol-based resin film constituting the polarizer can be formed by any suitable method (for example, a casting method in which a solution obtained by dissolving a resin in water or an organic solvent is cast, a casting method, an extrusion method). . The thickness of the polarizer can be appropriately set according to the purpose and application of the LCD in which the polarizing plate is used, but is typically 5 to 80 μm.

  As a method for producing a polarizer, any appropriate method can be adopted depending on the purpose, materials used, conditions, and the like. Typically, a method is employed in which the polyvinyl alcohol-based resin film is subjected to a series of production steps including swelling, dyeing, crosslinking, stretching, washing with water, and drying steps. In each processing step except the drying step, the treatment is performed by immersing the polyvinyl alcohol-based resin film in a bath containing a solution used in each step. The order, frequency, and presence / absence of each treatment of swelling, dyeing, crosslinking, stretching, washing with water, and drying can be appropriately set according to the purpose, materials used, conditions, and the like. For example, several processes may be performed simultaneously in one process, and a specific process may be omitted. More specifically, for example, the stretching process may be performed after the dyeing process, may be performed before the dyeing process, or may be performed simultaneously with the swelling process, the dyeing process, and the crosslinking process. Further, for example, it can be suitably employed to perform the crosslinking treatment before and after the stretching treatment. Further, for example, the water washing process may be performed after all the processes, or may be performed only after a specific process.

  The swelling step is typically performed by immersing the polyvinyl alcohol resin film in a treatment bath (swelling bath) filled with water. By this treatment, dirt on the surface of the polyvinyl alcohol-based resin film and an anti-blocking agent can be washed, and unevenness such as uneven dyeing can be prevented by swelling the polyvinyl alcohol-based resin film. Glycerin, potassium iodide, or the like can be appropriately added to the swelling bath. The temperature of the swelling bath is typically about 20 to 60 ° C., and the immersion time in the swelling bath is typically about 0.1 to 10 minutes.

  The dyeing step is typically performed by immersing the polyvinyl alcohol resin film in a treatment bath (dye bath) containing a dichroic substance such as iodine. As the solvent used for the dye bath solution, water is generally used, but an appropriate amount of an organic solvent compatible with water may be added. The dichroic substance is typically used at a ratio of 0.1 to 1.0 part by weight with respect to 100 parts by weight of the solvent. When iodine is used as the dichroic substance, the dye bath solution preferably further contains an auxiliary agent such as iodide. This is because the dyeing efficiency is improved. The auxiliary is preferably used in a proportion of 0.02 to 20 parts by weight, more preferably 2 to 10 parts by weight, with respect to 100 parts by weight of the solvent. Specific examples of iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Titanium is mentioned. The temperature of the dyeing bath is typically about 20 to 70 ° C., and the immersion time in the dyeing bath is typically about 1 to 20 minutes.

  The crosslinking step is typically performed by immersing the dyed polyvinyl alcohol resin film in a treatment bath (crosslinking bath) containing a crosslinking agent. Arbitrary appropriate crosslinking agents can be employ | adopted as a crosslinking agent. Specific examples of the crosslinking agent include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. These can be used alone or in combination. As the solvent used for the solution of the crosslinking bath, water is generally used, but an appropriate amount of an organic solvent having compatibility with water may be added. The crosslinking agent is typically used at a ratio of 1 to 10 parts by weight with respect to 100 parts by weight of the solvent. When the concentration of the crosslinking agent is less than 1 part by weight, sufficient optical properties cannot often be obtained. When the concentration of the crosslinking agent exceeds 10 parts by weight, the stretching force generated in the film during stretching increases, and the resulting polarizing plate may shrink. The solution of the crosslinking bath preferably further contains an auxiliary agent such as iodide. This is because it is easy to obtain uniform characteristics in the plane. The concentration of the auxiliary agent is preferably 0.05 to 15% by weight, more preferably 0.5 to 8% by weight. Specific examples of iodide are the same as in the dyeing step. The temperature of the crosslinking bath is typically about 20 to 70 ° C, preferably 40 to 60 ° C. The immersion time in the crosslinking bath is typically about 1 second to 15 minutes, preferably 5 seconds to 10 minutes.

  The stretching process may be performed at any stage as described above. Specifically, it may be performed after the dyeing process, may be performed before the dyeing process, may be performed simultaneously with the swelling process, the dyeing process, and the crosslinking process, or may be performed after the crosslinking process. The cumulative draw ratio of the polyvinyl alcohol-based resin film needs to be 5 times or more, preferably 5 to 7 times, and more preferably 5 to 6.5 times. When the cumulative draw ratio is less than 5 times, it may be difficult to obtain a polarizing plate with a high degree of polarization. When the cumulative draw ratio exceeds 7 times, the polyvinyl alcohol-based resin film (polarizer) may be easily broken. Arbitrary appropriate methods may be employ | adopted as a specific method of extending | stretching. For example, when the wet stretching method is adopted, the polyvinyl alcohol-based resin film is stretched at a predetermined magnification in a treatment bath (stretching bath). As the stretching bath solution, a solution in which various metal salts, iodine, boron or zinc compounds are added to a solvent such as water or an organic solvent (for example, ethanol) is preferably used.

  The water washing step is typically performed by immersing the polyvinyl alcohol-based resin film subjected to the above-described various treatments in a treatment bath (water washing bath). An unnecessary residue of the polyvinyl alcohol-based resin film can be washed away by the water washing step. The washing bath may be pure water or an aqueous solution of iodide (for example, potassium iodide or sodium iodide). The concentration of the iodide aqueous solution is preferably 0.1 to 10% by mass. An auxiliary agent such as zinc sulfate or zinc chloride may be added to the aqueous iodide solution. The temperature of the washing bath is preferably 10 to 60 ° C, more preferably 30 to 40 ° C. The immersion time is typically 1 second to 1 minute. The water washing step may be performed only once, or may be performed a plurality of times as necessary. When implemented several times, the kind and density | concentration of the additive contained in the washing bath used for each process can be adjusted suitably. For example, the water washing step includes a step of immersing the polymer film in an aqueous potassium iodide solution (0.1 to 10% by mass, 10 to 60 ° C.) for 1 second to 1 minute, and a step of rinsing with pure water.

  Any appropriate drying method (for example, natural drying, air drying, heat drying) may be employed as the drying step. For example, in the case of heat drying, the drying temperature is typically 20 to 80 ° C., and the drying time is typically 1 to 10 minutes. A polarizer is obtained as described above.

  In the polarizing plate of the present invention, the polarizer is bonded to the polarizer protective film of the present invention via an adhesive layer.

  In this invention, adhesion | attachment with a polarizer protective film and a polarizer is performed through the adhesive bond layer formed from an adhesive agent. This adhesive layer is preferably a layer formed from a polyvinyl alcohol-based adhesive. The polyvinyl alcohol-based adhesive contains a polyvinyl alcohol-based resin and a crosslinking agent.

  The polyvinyl alcohol-based resin is not particularly limited. For example, polyvinyl alcohol obtained by saponifying polyvinyl acetate; a derivative thereof; and a saponified product of a copolymer with a monomer having copolymerizability with vinyl acetate. Modified polyvinyl alcohol obtained by acetalization, urethanization, etherification, grafting, phosphoric esterification, etc. of polyvinyl alcohol. Examples of the monomer include unsaturated carboxylic acids such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, (meth) acrylic acid, and esters thereof; α-olefins such as ethylene and propylene, (meth) Examples include allyl sulfonic acid (soda), sulfonic acid soda (monoalkyl malate), disulfonic acid soda alkyl maleate, N-methylol acrylamide, acrylamide alkyl sulfonic acid alkali salt, N-vinyl pyrrolidone, N-vinyl pyrrolidone derivatives, and the like. . These polyvinyl alcohol resins may be used alone or in combination of two or more.

  From the viewpoint of adhesiveness, the polyvinyl alcohol-based resin preferably has an average degree of polymerization of 100 to 3000, more preferably 500 to 3000, and an average degree of saponification of preferably 85 to 100 mol%, more preferably 90. ˜100 mol%.

  As the polyvinyl alcohol resin, a polyvinyl alcohol resin having an acetoacetyl group can be used. A polyvinyl alcohol-based resin having an acetoacetyl group is a polyvinyl alcohol-based adhesive having a highly reactive functional group, and is preferable in terms of improving the durability of the polarizing plate.

  A polyvinyl alcohol-based resin containing an acetoacetyl group is obtained by reacting a polyvinyl alcohol-based resin with diketene by a known method. For example, a method in which a polyvinyl alcohol resin is dispersed in a solvent such as acetic acid and diketene is added thereto, and a polyvinyl alcohol resin is previously dissolved in a solvent such as dimethylformamide or dioxane, and diketene is added thereto. And the like. Moreover, the method of making diketene gas or liquid diketene contact directly to polyvinyl alcohol is mentioned.

  The degree of acetoacetyl group modification of the polyvinyl alcohol resin having an acetoacetyl group is not particularly limited as long as it is 0.1 mol% or more. If it is less than 0.1 mol%, the water resistance of the adhesive layer is insufficient, which is inappropriate. The degree of acetoacetyl modification is preferably 0.1 to 40 mol%, more preferably 1 to 20 mol%. When the degree of acetoacetyl modification exceeds 40 mol%, the number of reaction points with the cross-linking agent decreases, and the effect of improving water resistance is small. The degree of acetoacetyl modification is a value measured by NMR.

As said crosslinking agent, what is used for the polyvinyl alcohol-type adhesive agent can be especially used without a restriction | limiting.
As the crosslinking agent, a compound having at least two functional groups having reactivity with the polyvinyl alcohol resin can be used. For example, alkylene diamines having two alkylene groups and two amino groups such as ethylene diamine, triethylene amine, hexamethylene diamine (hexamethylene diamine is preferred); tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylene propane tolylene Isocyanate adduct, triphenylmethane triisocyanate, methylene bis (4-phenylmethane triisocyanate, isophorone diisocyanate and isocyanates such as ketoxime block product or phenol block product; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di Or triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylo Epoxys such as rupropane triglycidyl ether, diglycidyl aniline, diglycidyl amine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde; glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, maleindialdehyde And dialdehydes such as phthaldialdehyde; amino-formaldehyde resins such as methylol urea, methylol melamine, alkylated methylol urea, alkylated methylolated melamine, acetoguanamine, condensates of benzoguanamine and formaldehyde; sodium, potassium, magnesium Divalent metals such as calcium, aluminum, iron and nickel, or salts of trivalent metals and oxides thereof. Is to, melamine-based crosslinking agent is preferably, suitable in particular melamine.

  The amount of the crosslinking agent is preferably 0.1 to 35 parts by weight, more preferably 10 to 25 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin. On the other hand, in order to further improve the durability, the crosslinking agent can be blended in a range of more than 30 parts by weight and 46 parts by weight or less with respect to 100 parts by weight of the polyvinyl alcohol resin. In particular, when a polyvinyl alcohol-based resin containing an acetoacetyl group is used, it is preferable to use the crosslinking agent in an amount exceeding 30 parts by weight. Water resistance improves by mix | blending a crosslinking agent in the range of more than 30 weight part and 46 weight part or less.

  The polyvinyl alcohol-based adhesive further includes coupling agents such as silane coupling agents and titanium coupling agents, various tackifiers, ultraviolet absorbers, antioxidants, heat stabilizers, hydrolysis stabilizers, and the like. A stabilizer or the like can also be blended.

  The polarizer protective film of the present invention can be subjected to an easy adhesion treatment for improving adhesion to the surface in contact with the polarizer. Examples of the easy adhesion treatment include surface treatment such as corona treatment, plasma treatment, low-pressure UV treatment, and saponification treatment, and a method of forming an anchor layer, and these can be used in combination. Among these, a corona treatment, a method of forming an anchor layer, and a method of using these in combination are preferable.

  Examples of the anchor layer include a silicone layer having a reactive functional group. The material of the silicone layer having a reactive functional group is not particularly limited. For example, an isocyanate group-containing alkoxysilanol, an amino group-containing alkoxysilanol, a mercapto group-containing alkoxysilanol, a carboxy-containing alkoxysilanol, an epoxy group-containing Examples thereof include alkoxysilanols, vinyl-type unsaturated group-containing alkoxysilanols, halogen group-containing alkoxylanols, and isocyanate group-containing alkoxysilanols, and amino silanols are preferred. Furthermore, the adhesive force can be strengthened by adding a titanium-based catalyst or a tin-based catalyst for efficiently reacting the silanol. Moreover, you may add another additive to the silicone which has the said reactive functional group. Specifically, terpene resins, phenol resins, terpene-phenol resins, rosin resins, xylene resins and other tackifiers, UV absorbers, antioxidants, heat stabilizers and other stabilizers may be used.

  The silicone layer having the reactive functional group is formed by coating and drying by a known technique. The thickness of the silicone layer is preferably 1 to 100 nm, more preferably 10 to 50 nm after drying. During coating, silicone having a reactive functional group may be diluted with a solvent. The dilution solvent is not particularly limited, and examples thereof include alcohols. The dilution concentration is not particularly limited, but is preferably 1 to 5% by weight, more preferably 1 to 3% by weight.

  The adhesive layer is formed by applying the adhesive to either side or both sides of the polarizer protective film and to either side or both sides of the polarizer. After bonding a polarizer protective film and a polarizer, a drying process is given and the adhesive bond layer which consists of an application | coating drying layer is formed. This can also be bonded after forming the adhesive layer. Bonding of a polarizer and a polarizer protective film can be performed with a roll laminator or the like. The heating and drying temperature and drying time are appropriately determined according to the type of adhesive.

  The thickness of the adhesive layer is preferably 0.01 to 10 μm, and more preferably 0.03 to 5 μm, because it is not preferable in terms of adhesiveness of the polarizer protective film if the thickness after drying becomes too thick. .

  Bonding of the polarizer protective film to the polarizer can be bonded to both sides of the polarizer on one side of the polarizer protective film.

  In addition, the polarizer protective film of the polarizer can be bonded to one side of the polarizer by bonding on one side of the polarizer protective film, and the cellulose resin can be bonded to the other side.

  The cellulose resin is not particularly limited, but triacetyl cellulose is preferable in terms of transparency and adhesiveness. The thickness of the cellulosic resin is preferably 30 to 100 μm, more preferably 40 to 80 μm. If the thickness is less than 30 μm, the film strength is lowered and workability is inferior.

  The polarizing plate according to the present invention may have an adhesive layer as at least one of the outermost layers (such a polarizing plate may be referred to as an adhesive polarizing plate). As a particularly preferred embodiment, a pressure-sensitive adhesive layer for adhering to another member such as another optical film or a liquid crystal cell can be provided on the side of the polarizer protective film where the polarizer is not adhered.

  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 used as a base polymer. It can select suitably and 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 and heat resistance can be preferably used. In particular, an acrylic pressure-sensitive adhesive made of an acrylic polymer having 4 to 12 carbon atoms is preferable.

  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 pressure-sensitive adhesive layer is, for example, a natural or synthetic resin, in particular, a tackifier resin, a filler or pigment made of glass fiber, glass beads, metal powder, other inorganic powders, a colorant, an antioxidant. An additive to be added to the pressure-sensitive adhesive layer such as an agent may be contained.

  Moreover, the adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.

  The attachment of the pressure-sensitive adhesive layer 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 a pressure-sensitive adhesive layer is formed on a separator according to the above, and the surface is applied to a polarizer protective film. The method of transferring to is included.

  The pressure-sensitive adhesive layer can be provided on one side or both sides of the polarizing plate as a superposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as adhesive layers with a different composition, a kind, thickness, etc. in the front and back of a polarizing plate.

  The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is preferably 1 to 40 μm, more preferably 5 to 30 μm, and particularly preferably 10 to 25 μm. When the thickness is less than 1 μm, the durability is deteriorated. When the thickness is more than 40 μm, floating or peeling due to foaming or the like is liable to occur, resulting in poor appearance.

  In order to improve the adhesion between the polarizer protective film and the pressure-sensitive adhesive layer, an anchor layer may be provided between the layers.

  As the anchor layer, an anchor layer selected from polyurethane, polyester and polymers containing an amino group in the molecule is preferably used, and polymers containing an amino group in the molecule are particularly preferably used. Polymers containing amino groups in the molecule are good because the amino groups in the molecule exhibit interactions such as reaction or ionic interaction with carboxyl groups in the adhesive and polar groups in the conductive polymer. Adhesion is ensured.

  Examples of the polymer containing an amino group in the molecule include, for example, polyethyleneimine, polyallylamine, polyvinylamine, polyvinylpyridine, polyvinylpyrrolidine, and amino-containing groups such as dimethylaminoethyl acrylate shown as a copolymer monomer of the acrylic pressure-sensitive adhesive. Examples thereof include polymers of contained monomers.

  In order to impart antistatic properties to the anchor layer, an antistatic agent may be added. Antistatic agents for imparting antistatic properties include ionic surfactant systems, conductive polymer systems such as polyaniline, polythiophene, polypyrrole, and polyquinoxaline, and metal oxide systems such as tin oxide, antimony oxide, and indium oxide. In particular, a conductive polymer system is preferably used from the viewpoint of optical characteristics, appearance, antistatic effect, and stability of the antistatic effect when heated and humidified. Among these, water-soluble conductive polymers such as polyaniline and polythiophene or water-dispersible conductive polymers are particularly preferably used. This is because, when a water-soluble conductive polymer or a water-dispersible conductive polymer is used as a material for forming the antistatic layer, it is possible to suppress deterioration of the optical film substrate due to an organic solvent during the coating process.

  In the present invention, the polarizer, polarizer protective film, and the like that form the polarizing plate described above, and the pressure-sensitive adhesive layer, for example, salicylic acid ester compounds, benzophenol compounds, benzotriazole compounds, and cyanoacrylate compounds. A compound or a compound having ultraviolet absorbing ability by a method such as a method of treating with a UV absorber such as a nickel complex salt compound may be used.

  The polarizing plate of the present invention may be provided on either the viewing side or the backlight side of the liquid crystal cell or on both sides, and is not limited.

  Next, the image display apparatus of the present invention will be described. The image display device of the present invention includes at least one polarizing plate of the present invention. Here, a liquid crystal display device will be described as an example, but it goes without saying that the present invention can be applied to any display device that requires a polarizing plate. Specific examples of the image display device to which the polarizing plate of the present invention can be applied include a self-luminous display device such as an electroluminescence (EL) display, a plasma display (PD), and a field emission display (FED: Field Emission Display). Can be mentioned. FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. In the illustrated example, a transmissive liquid crystal display device will be described, but it goes without saying that the present invention is also applied to a reflective liquid crystal display device and the like.

  The liquid crystal display device 100 includes a liquid crystal cell 10, retardation films 20 and 20 ′ disposed across the liquid crystal cell 10, and polarizing plates 30 and 30 ′ disposed outside the retardation films 20 and 20 ′. A light guide plate 40, a light source 50, and a reflector 60 are provided. The polarizing plates 30 and 30 'are arranged so that their polarization axes are orthogonal to each other. The liquid crystal cell 10 includes a pair of glass substrates 11 and 11 ′ and a liquid crystal layer 12 as a display medium disposed between the substrates. One substrate 11 is provided with a switching element (typically a TFT) for controlling the electro-optical characteristics of the liquid crystal, a scanning line for supplying a gate signal to the active element, and a signal line for supplying a source signal ( Neither is shown). The other glass substrate 11 ′ is provided with a color layer constituting a color filter and a light shielding layer (black matrix layer) (both not shown). The distance (cell gap) between the substrates 11 and 11 ′ is controlled by the spacer 13. In the liquid crystal display device of the present invention, the polarizing plate of the present invention described above is employed as at least one of the polarizing plates 30 and 30 '.

  For example, in the case of the TN mode, in such a liquid crystal display device 100, when no voltage is applied, the liquid crystal molecules of the liquid crystal layer 12 are arranged in a state where the polarization axis is shifted by 90 degrees. In such a state, incident light that is transmitted through only light in one direction by the polarizing plate is twisted 90 degrees by liquid crystal molecules. As described above, since the polarizing plates are arranged so that the polarization axes thereof are orthogonal to each other, the light (polarized light) reaching the other polarizing plate is transmitted through the polarizing plate. Therefore, when no voltage is applied, the liquid crystal display device 100 performs white display (normally white method). On the other hand, when a voltage is applied to such a liquid crystal display device 100, the arrangement of liquid crystal molecules in the liquid crystal layer 12 changes. As a result, the light (polarized light) that has reached the other polarizing plate cannot be transmitted through the polarizing plate, resulting in black display. An image is formed by switching such display for each pixel using an active element.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. Unless otherwise indicated, parts and percentages in the examples are based on weight. Evaluation was performed as follows.

<Film strength>
Using an autograph “AG-1” manufactured by Shimadzu Corporation, tensile strength and tensile elongation were measured.

<Film retardation>
An in-plane retardation Δnd and a thickness direction retardation Rth were measured using an automatic birefringence meter “KOBRA-21ADH” manufactured by Oji Scientific Instruments.

<Haze>
Based on JIS-K6714, it measured using "HAZEMETER HM-150" by Murakami Color Research Laboratory.

<Moisture permeability>
Based on JIS-Z0208, it was measured by leaving it in an environment of 40 ° C. and a relative humidity of 92%.

<Adhesiveness between polarizer protective film and polarizer>
The state when the polarizing plate (100 mm × 100 mm) was twisted by hand and threaded was evaluated according to the following criteria.
A: The polarizer and the polarizer protective film are integrated with each other so that peeling does not occur.
(Triangle | delta): Peeling is recognized by a polarizer, a polarizer protective film, and an edge part.
X: Peeling is recognized between the polarizer and the polarizer protective film.

<Appearance of polarizing plate>
The appearance of the obtained polarizing plate was evaluated. Evaluation was performed visually with respect to a polarizing plate of 50 mm × 50 mm according to the following criteria.
○: There are no floats or streaks.
X: A float and a stripe are not seen.
The term “floating” means that the polarizer and the polarizer protective film are not in close contact with each other, and the term “streak” means that the polarizer protective film or the polarizer has a very small area but is adhered by itself.

As the (meth) acrylic resin, “Acrypet VRL20A” (Tg = 109 ° C.) manufactured by Mitsubishi Rayon Co., Ltd. was used, and an acrylic resin molding material was prepared by the following method.
Acrypet VRL20A was vacuum-dried at 100 ° C. to degas water and dissolved oxygen, and as a styrene resin, “Septon 2007” manufactured by Kuraray Co., Ltd. (styrene content: 30% by weight, 2. at 240 ° C.). 5 parts by weight of MFR value at 16 kgf: 2.4 g / 10 min), 10 parts by weight of “AQUALIC AS” manufactured by Nippon Shokubai Co., Ltd., UV absorber (“TINUVIN 1577” manufactured by Ciba Specialty Chemicals) 1 part by weight and 1 part by weight of “Adeka Stub LA-31” manufactured by Asahi Denka Kogyo Co., Ltd.) and supplied to Toshiba Machine's twin screw extruder “TEM35B” in which the raw material hopper to the extruder are replaced with nitrogen. Then, it was melted at a cylinder set temperature of 230 to 270 ° C. and pelletized to obtain raw material pellets.
The raw material pellets are vacuum-dried at 100 ° C., supplied to a single-screw extruder “SE-65” manufactured by Toshiba Machine in which nitrogen is substituted from the raw material hopper to the extruder, and melted at a cylinder set temperature of 230 to 270 ° C. After passing through a coat hanger type (lip length: 500 mm, lip opening: 0.6 mm, 260 ° C.) T-die and cooling with a 120 ° C. chrome plating casting roll and a 90 ° C. cooling chrome plating casting roll A film raw material was prepared using a film winder.
The original film was passed through a slitting machine equipped with a shear cutter and aligned to a width of 400 mm.
The original film was in the range of 120 ± 10 μm in thickness, and was a uniform film with no defects such as bubbles, voids and scratches in appearance.
A sample of a predetermined shape was cut out from the film raw material after slit processing and evaluated.
The evaluation results of the obtained film are shown in Table 1.

“Acrypet VH” (Tg = 113 ° C.) manufactured by Mitsubishi Rayon Co., Ltd. is used as the (meth) acrylic resin, and “Septon 4044” manufactured by Kuraray Co., Ltd. (styrene content: 32 wt. %) Was used in the same manner as in Example 1 to prepare a film original.
The original film was in a range of 120 ± 7 μm in thickness, and was a uniform film with no defects such as bubbles, voids, and scratches in appearance.
A sample of a predetermined shape was cut out from the film raw material after slit processing and evaluated.
The evaluation results of the obtained film are shown in Table 1.

“Acrypet VH” (Tg = 113 ° C.) manufactured by Mitsubishi Rayon Co., Ltd. is used as the (meth) acrylic resin, and “Septon 4055” manufactured by Kuraray Co., Ltd. (styrene content: 30 wt. %) Was used in the same manner as in Example 1 to prepare a film original.
The film original was in the range of thickness 120 ± 9 μm, and it was a uniform film with no defects such as bubbles, voids and scratches in appearance.
A sample of a predetermined shape was cut out from the film raw material after slit processing and evaluated.
The evaluation results of the obtained film are shown in Table 1.

“Acrypet VH” manufactured by Mitsubishi Rayon Co., Ltd. (Tg = 113 ° C.) is used as the (meth) acrylic resin, and “H1041” manufactured by Asahi Kasei Chemicals Co., Ltd. (styrene content: 30 weight). %, MFR value at 2.16 kgf at 240 ° C .: 5.0 g / 10 min) was used in the same manner as in Example 1 to prepare a film original fabric.
The film original was in the range of 120 ± 8 μm in thickness, and was a uniform film with no defects such as bubbles, voids and scratches in appearance.
A sample of a predetermined shape was cut out from the film raw material after slit processing and evaluated.
The evaluation results of the obtained film are shown in Table 1.

A film original fabric was prepared in the same manner as in Example 1 except that “Septon 4044” (styrene content: 32% by weight) manufactured by Kuraray Co., Ltd. was used as the styrene resin.
The original film was in a range of 120 ± 7 μm in thickness, and was a uniform film with no defects such as bubbles, voids, and scratches in appearance.
A sample of a predetermined shape was cut out from the film raw material after slit processing and evaluated.
The evaluation results of the obtained film are shown in Table 1.

A film original fabric was prepared in the same manner as in Example 1 except that “Septon 4055” (styrene content: 30% by weight) manufactured by Kuraray Co., Ltd. was used as the styrene resin.
The original film was in a range of 120 ± 7 μm in thickness, and was a uniform film with no defects such as bubbles, voids, and scratches in appearance.
A sample of a predetermined shape was cut out from the film raw material after slit processing and evaluated.
The evaluation results of the obtained film are shown in Table 1.

As Example 1 except that “H1041” manufactured by Asahi Kasei Chemicals Co., Ltd. (styrene content: 30% by weight, MFR value at 2.16 kgf at 240 ° C .: 5.0 g / 10 min) was used as the styrene resin. In the same manner, an original film was prepared.
The film original was in the range of thickness 120 ± 9 μm, and it was a uniform film with no defects such as bubbles, voids and scratches in appearance.
A sample of a predetermined shape was cut out from the film raw material after slit processing and evaluated.
The evaluation results of the obtained film are shown in Table 1.
[Comparative Example 1]

As a (meth) acrylic resin, “Acrypet IRH70” (Tg = 83 ° C.) manufactured by Mitsubishi Rayon Co., Ltd. was used, and an acrylic resin molding material was prepared by the following method.
Acrypet IRH70 was vacuum-dried at 80 ° C. to degas water and dissolved oxygen, and as a styrene resin, “Septon 2007” manufactured by Kuraray Co., Ltd. (styrene content: 30 wt%, at 240 ° C. 2. 5 parts by weight of MFR value at 16 kgf: 2.4 g / 10 min), 10 parts by weight of “AQUALIC AS” manufactured by Nippon Shokubai Co., Ltd., UV absorber (“TINUVIN 1577” manufactured by Ciba Specialty Chemicals) 1 part by weight and 1 part by weight of “Adeka Stub LA-31” manufactured by Asahi Denka Kogyo Co., Ltd.) and supplied to a twin-screw extruder “TEM35B” manufactured by TOSHIBA MACHINE with nitrogen replacement from the raw material hopper to the extruder. Then, it was melted at a cylinder set temperature of 230 to 270 ° C. and pelletized to obtain raw material pellets.
The raw material pellets were vacuum-dried at 90 ° C., supplied to a single-screw extruder “SE-65” manufactured by Toshiba Machine with nitrogen replacement from the raw material hopper to the extruder, and melted at a cylinder set temperature of 210 to 250 ° C. After passing through a coat-hanger type (lip length: 500 mm, lip opening: 0.6 mm, 245 ° C.) T-die and cooling with a 100 ° C. chrome plating casting roll and a 70 ° C. cooling chrome plating casting roll A film raw material was prepared using a film winder.
The original film was passed through a slitting machine equipped with a shear cutter and aligned to a width of 400 mm.
The original film was in the range of 120 ± 11 μm in thickness, and was a uniform film with no defects such as bubbles, voids and scratches in appearance.
A sample of a predetermined shape was cut out from the film raw material after slit processing and evaluated.
The evaluation results of the obtained film are shown in Table 2.
[Comparative Example 2]

As the (meth) acrylic resin, “Acrypet VH” (Tg = 113 ° C.) manufactured by Mitsubishi Rayon Co., Ltd. was used, and the addition amount of the styrene resin was 12 parts by weight with respect to the (meth) acrylic resin. Except for this, a film original fabric was prepared in the same manner as in Example 1.
The original film was in a range of 120 ± 11 μm in thickness, and it was a uniform film with no defects such as bubbles, voids and scratches in appearance.
A sample of a predetermined shape was cut out from the film raw material after slit processing and evaluated.
The evaluation results of the obtained film are shown in Table 2.
[Comparative Example 3]

“Acrypet VH” (Tg = 113 ° C.) manufactured by Mitsubishi Rayon Co., Ltd. is used as the (meth) acrylic resin, and “Septon 4044” manufactured by Kuraray Co., Ltd. (styrene content: 32 wt. %) And the amount of styrene resin added was 15 parts by weight with respect to the (meth) acrylic resin, and a film original fabric was prepared in the same manner as in Example 1.
The original film was in the range of 120 ± 10 μm in thickness, and was a uniform film with no defects such as bubbles, voids and scratches in appearance.
A sample of a predetermined shape was cut out from the film raw material after slit processing and evaluated.
The evaluation results of the obtained film are shown in Table 2.
[Comparative Example 4]

“Acrypet VH” manufactured by Mitsubishi Rayon Co., Ltd. (Tg = 113 ° C.) is used as the (meth) acrylic resin, and “H1041” manufactured by Asahi Kasei Chemicals Co., Ltd. (styrene content: 30 weight). %, MFR value at 2.16 kgf at 240 ° C .: 5.0 g / 10 min), and the amount of styrene resin added was 11 parts by weight with respect to the (meth) acrylic resin. In the same manner as above, a film original fabric was prepared.
The film original was in the range of 120 ± 8 μm in thickness, and was a uniform film with no defects such as bubbles, voids and scratches in appearance.
A sample of a predetermined shape was cut out from the film raw material after slit processing and evaluated.
The evaluation results of the obtained film are shown in Table 2.

(Polarizer)
A polyvinyl alcohol film having a thickness of 80 μm was dyed in an aqueous iodine solution of 5% by weight (weight ratio: iodine / potassium iodide = 1/10). Next, after being immersed in an aqueous solution containing 3% by weight boric acid and 2% by weight potassium iodide and further stretched to 5.5 times in an aqueous solution containing 4% by weight boric acid and 3% by weight potassium iodide. It was immersed in a 5% by weight aqueous potassium iodide solution. Then, it dried for 3 minutes in 40 degreeC oven, and obtained the 30-micrometer-thick polarizer.

(Corona treatment of polarizer protective film)
One side of the polarizer protective film obtained in Example 1 was subjected to corona treatment at a discharge amount of 133 w · min / m ² .

(Easily adhesive layer)
A solution prepared by adding 66.7 parts of isopropyl alcohol to 100 parts of a silane coupling agent (APZ-6601) manufactured by Toray Dow Corning Silicone Co., Ltd. was applied to the corona-treated surface of the film obtained above. The coating was applied with bar # 5 to evaporate volatile components. The thickness of the anchor layer after evaporation was 50 nm.

(adhesive)
A polyvinyl alcohol adhesive aqueous solution prepared by adjusting an aqueous solution containing 20 parts by weight of methylolmelamine to 100 parts by weight of an acetoacetyl-modified polyvinyl alcohol resin (degree of acetylation 13%) to a concentration of 0.5% by weight It was adjusted.

(Preparation of polarizing plate)
The polarizer protective film was bonded to both surfaces of the polarizer using a polyvinyl alcohol-based adhesive so that the anchor layer of the polarizer protective film was in contact. Each of the polyvinyl alcohol-based adhesives was applied to the surface of the polarizer protective film and dried at 70 ° C. for 10 minutes to obtain a polarizing plate.

(Adhesive)
As a base polymer, a solution (solid content 30) containing an acrylic polymer having a weight average molecular weight of 2 million consisting of a copolymer of butyl acrylate: acrylic acid: 2-hydroxyethyl acrylate = 100: 5: 0.1 (weight ratio) %) Was used. Viscosity adjustment of 4 parts of Coronate L manufactured by Nippon Polyurethane Co., Ltd., which is an isocyanate-based polyfunctional compound, to 100 parts of polymer solids and 0.5 part of an additive (KBM403, manufactured by Shin-Etsu Silicone) A solvent (ethyl acetate) was added to prepare an adhesive solution (solid content 12%). The pressure-sensitive adhesive solution was applied on a release film (polyethylene terephthalate substrate: Diafoil MRF38, manufactured by Mitsubishi Chemical Polyester) so that the thickness after drying was 25 μm, and then dried in a hot air circulation oven, An adhesive layer was formed.

(Polarizing plate anchor layer)
A polyethylenimine adduct of polyacrylic acid ester (trade name: Polyment NK380, manufactured by Nippon Shokubai Co., Ltd.) was diluted 50 times with methyl isobutyl ketone. This was coated and dried on the outside of the polarizing plate using a wire bar (# 5) so that the thickness after drying was 50 nm.

(Preparation of adhesive polarizing plate)
A release film having the pressure-sensitive adhesive layer formed thereon was bonded to the anchor layer of the polarizing plate to prepare an adhesive-type polarizing plate.

(Evaluation)
When the adhesion between the polarizer protective film and the polarizer in the obtained polarizing plate and the appearance were evaluated, the adhesion between the polarizer protective film and the polarizer was ○ (the polarizer and the polarizer protective film were integrated and peeled off). The appearance was ◯ (no floating or streaks).

1 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal cell 11, 11 'Glass substrate 12 Liquid crystal layer 13 Spacer 20, 20' Retardation film 30, 30 'Polarizing plate 40 Light guide plate 50 Light source 60 Reflector 100 Liquid crystal display device

Claims (5)

A polarizer protective film comprising a (meth) acrylic resin having a Tg of 100 ° C. or higher as a main component,
A polarizer protective film having an in-plane retardation Δnd of 1.0 or less, a thickness direction retardation Rth of 3.0 or less, and a moisture permeability of 65 g / m ² · 24 hr or less. A polarizing plate comprising a polarizer formed from a polyvinyl alcohol-based resin and the polarizer protective film according to claim 1,
A polarizing plate, wherein the polarizer is bonded to the polarizer protective film via an adhesive layer.   The polarizing plate according to claim 2, wherein the adhesive layer is a layer formed from a polyvinyl alcohol-based adhesive.   The polarizing plate of Claim 2 or 3 which has an adhesive layer as at least one of outermost layers. An image display device comprising at least one polarizing plate according to claim 2.

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