Polarizing plate and image display device

Abstract

This invention provides a polarizing plate that helps improve the display characteristics of an image display device. The polarizing plate according to an embodiment of this invention includes: a multilayer film having a substrate and a surface treatment layer, and a polarizing element disposed on the substrate side of the multilayer film. The reflectivity on the surface treatment layer side is 2% or less, the haze on the surface treatment layer side is 1% to 13% or more, and the transmittance of the polarizing plate is 45.5% or more. The polarizing plate is used in an organic EL panel.

Description

[Technical Field]

[0001] This invention relates to a polarizing plate and an image display device. [Previous Technology]

[0002] In image display panels mounted on image display devices, polarizing plates are generally used. Typically, polarizing plates with a phase retardation layer, which integrate a polarizing plate and a phase retardation plate, are widely used (e.g., Patent Document 1). In recent years, electroluminescent (EL) display devices (e.g., organic EL display devices) have been rapidly gaining popularity as image display devices (representatively smartphones and televisions), and their applications are expanding further. For example, applications in laptops and tablets are being researched. Furthermore, with the expansion of applications, excellent display characteristics are required under all circumstances. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent No. 3325560 [Summary of the Invention]

[0004] [The problem the invention aims to solve]

[0005] In view of the above, the main objective of the present invention is to provide a polarizing plate that can help improve the display characteristics of an image display device. [Technical Means for Solving the Problem]

[0006] According to an embodiment of the present invention, a polarizing plate is provided. The polarizing plate includes: a laminated film having a substrate and a surface treatment layer, and a polarizing element disposed on the substrate side of the laminated film, wherein the reflectivity on the surface treatment layer side is 2% or less, the haze on the surface treatment layer side is 1% to 13% or more, the transmittance of the polarizing plate is 45.5% or more, and the polarizing plate is used in an organic EL panel. In one embodiment, the surface treatment layer includes a first layer, the first layer includes a resin component and hollow particles, and the first layer includes hollow particles in an amount of 11 parts by weight or more relative to 100 parts by weight of the resin component. In another embodiment, the surface treatment layer includes a first layer, the first layer includes a resin component and hollow particles, and the first layer includes hollow particles in an amount of 40 parts by weight or less relative to 100 parts by weight of the resin component. In another embodiment, the polarizing plate further includes a retardation layer, wherein the in-plane phase difference Re(550) of the retardation layer is 100 nm to 190 nm. According to another embodiment of the present invention, an image display device is provided. The image display device includes: an image display panel body, and a polarizing plate disposed on the viewing side of the image display panel body. In one embodiment, the polarizing plate is located on the outermost surface of the viewing side. [Effects of the Invention]

[0007] According to the embodiments of the present invention, excellent display characteristics can be achieved.

Implementation Method

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to these embodiments. Furthermore, in order to make the description clearer, the drawings sometimes show the width, thickness, shape, etc. of each part in a patterned manner compared with the embodiments, but these are always examples and do not limit the interpretation of the present invention.

[0010] (Definitions of Terms and Symbols) The terms and symbols in this specification are defined as follows. (1) Refractive Index (nx, ny, nz) "nx" is the refractive index in the direction where the in-plane refractive index is the maximum (i.e., the slow axis direction), "ny" is the refractive index in the direction orthogonal to the slow axis (i.e., the fast axis direction), and "nz" is the refractive index in the thickness direction. (2) In-plane Phase Difference (Re) "Re(λ)" is the in-plane phase difference measured at 23°C with light of wavelength λnm. For example, "Re(550)" is the in-plane phase difference measured at 23°C with light of wavelength 550 nm. When the thickness of the layer (film) is set to d (nm), Re(λ) is calculated based on the formula: Re(λ)=(nx-ny)×d. (3) Phase Difference in Thickness Direction (Rth) "Rth(λ)" is the phase difference in the thickness direction measured at 23°C with light of wavelength λnm. For example, "Rth(550)" is the phase difference in the thickness direction measured at 23°C with light of wavelength 550 nm. When the thickness of the layer (film) is set to d (nm), Rth(λ) is calculated based on the formula: Rth(λ)=(nx-nz)×d.

[0011] FIG1 is a schematic cross-sectional view showing the schematic configuration of a polarizing plate according to one embodiment of the present invention. The polarizing plate (typically a circular polarizing plate) 100 includes: a polarizing element 10, a laminated film 20 disposed on one side of the polarizing element 10, a protective layer 30 disposed on the other side of the polarizing element 10, a retardation layer (typically a λ / 4 plate) 40, and an adhesive layer 50. The laminated film 20 includes a substrate 21 and a surface treatment layer 22 formed on the substrate 21, and the substrate 21 can function as a protective layer for the polarizing element 10. The protective layer 30 may be omitted, in which case the retardation layer 40 can function as a protective layer for the polarizing element.

[0012] The components constituting the polarizing plate can be attached to the polarizing element 10 via any suitable adhesive layer (not shown), for example, by rolling an area layer. Specific examples of adhesive layers include adhesive layers and bonding agents. For example, the laminated film 20 and the protective layer 30 are bonded to the polarizing element 10 via an adhesive layer (preferably using an active energy line curing adhesive). The thickness of the adhesive layer is preferably 0.4 μm or more, more preferably 0.4 μm to 3.0 μm, and even more preferably 0.6 μm to 2.0 μm. For example, the retardation layer 40 is bonded to the protective layer 30 via an adhesive layer. The thickness of the adhesive layer disposed between the protective layer 30 and the retardation layer 40 is, for example, 5 μm to 15 μm.

[0013] In the polarizing plate 100, an adhesive layer 50 is provided on the side of the polarizing element 10 where the multilayer film 20 is not disposed. The adhesive layer 50 allows the polarizing plate 100 to be attached to an image display panel included in an image display device. The thickness of the adhesive layer 50 is, for example, 10 μm to 20 μm. In practical use, a release liner is attached to the surface of the adhesive layer 50. The release liner can be temporarily attached until the polarizing plate is ready for use. By using the release liner, a roll of the polarizing plate can be formed, for example, while protecting the adhesive layer 50.

[0014] The polarizing plate can be in the form of a strip or a single sheet. Here, "strip" refers to a long and thin shape with a length that is sufficiently long relative to its width, such as a long and thin shape with a length that is more than 10 times, preferably more than 20 times, relative to its width. The strip-shaped polarizing plate can be rolled into a roll.

[0015] FIG2 is a schematic diagram illustrating the general configuration of an image display device according to one embodiment of the present invention, taking an organic EL display device as an example. Specifically, it is a schematic cross-sectional view showing a state in which a polarizing plate is disposed on an organic EL panel in an organic EL display device according to one embodiment of the present invention. In the organic EL panel 200, the polarizing plate 100 is disposed on the viewing side, and the polarizing element 10 is disposed closer to the organic EL panel body 70 than the laminated film 20. Specifically, the polarizing plate 100 is attached to the organic EL panel body 70 via an adhesive layer 50. The organic EL panel body 70 has: a substrate 71, and an upper structural layer 72, which includes a circuit layer containing thin-film transistors (TFTs), an organic light-emitting diode (OLED), a sealing film sealing the OLED, etc. In one embodiment, the surface treatment layer 22 of the laminated film 20 is located on the outermost surface of the image display device. Specifically, in the image display device, no protective material such as a glass plate is disposed on the polarizing plate 100 (surface treatment layer 22).

[0016] The transmittance of the polarizing plate is preferably greater than 45.0%, more preferably greater than 45.5%, and even more preferably greater than 46.0%. According to this polarizing plate, the luminous intensity of the image display panel can be suppressed, and it can also cope with long-term use of the image display device. Specifically, it can prevent image retention caused by prolonged image display. Here, the transmittance of the polarizing plate refers to the transmittance of the laminated portion excluding the retardation layer. Specifically, it refers to the transmittance of the laminated portion of the laminated film and the polarizing element, or the laminated portion of the laminated film, the polarizing element, and the protective layer.

[0017] [Polarizing element] The above-mentioned polarizing element is typically a resin film containing a dichroic substance (e.g., iodine). Examples of resin films include, for example, hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films.

[0018] The thickness of the polarizing element is preferably 18 μm or less, more preferably 15 μm or less, and even more preferably 12 μm or less. On the other hand, the thickness of the polarizing element is preferably 1 μm or more.

[0019] The polarizing element preferably exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The transmittance of a single element is, for example, 41.5% to 47.0%, preferably 42.0% to 47.0%, more preferably 44.5% to 47.0%. The polarization degree of the polarizing element is preferably 97.0% or higher, more preferably 99.0% or higher, and even more preferably 99.9% or higher. Here, the transmittance of a single element is a value obtained by measuring the laminate of the multilayer film and the polarizing element, or the multilayer film, the polarizing element and the protective layer as the measurement object.

[0020] The polarizing element can be manufactured by any suitable method. Specifically, the polarizing element can be made from a single layer of resin film or from a laminate of two or more layers.

[0021] A method for fabricating a polarizing element from the aforementioned single-layer resin film typically includes: subjecting the resin film to a dyeing treatment using iodine or a dichroic dye and a stretching treatment. As the resin film, for example, hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films can be used. The method may further include insolubility treatment, swelling treatment, crosslinking treatment, etc. This manufacturing method is well-known and commonly used in the art, therefore detailed description is omitted.

[0022] The polarizing element obtained using the above-described laminate can be manufactured, for example, using a laminate of a resin substrate and a resin film or resin layer (typically a PVA-based resin layer). Specifically, it can be manufactured as follows: a PVA-based resin solution is coated onto a resin substrate and dried to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer; the laminate is then stretched and dyed to form a polarizing element from the PVA-based resin layer. In this embodiment, it is preferable to form a PVA-based resin layer comprising a halide and a PVA-based resin on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, if necessary, stretching may further include air stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. In addition, in this embodiment, it is preferable to subject the laminate to a drying shrinkage treatment in which it shrinks by 2% or more in the width direction by being heated while being conveyed along the length direction. Representatively, the manufacturing method of this embodiment includes sequentially performing an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment on the laminate. By introducing air-assisted stretching, even when PVA is coated on a thermoplastic resin, the crystallinity of PVA can be improved, resulting in higher optical properties. Furthermore, by simultaneously improving the alignment of PVA beforehand, problems such as reduced alignment or dissolution of PVA can be prevented when immersed in water during subsequent dyeing and stretching steps, further achieving higher optical properties. Moreover, when the PVA-based resin layer is immersed in a liquid, compared to the case where the PVA-based resin layer does not contain halides, the disorder of PVA molecular alignment and the reduction of alignment can be suppressed, achieving higher optical properties. Furthermore, by shrinking the laminate in the width direction through the drying shrinkage treatment, higher optical properties can be achieved. A polarizing plate can be obtained by peeling off the resin substrate from the laminated resin substrate / polarizing element, either on a release surface or on a protective layer on the opposite side of the release surface. Details of the manufacturing method for such a polarizing element are described, for example, in Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire contents of these publications are incorporated herein by reference.

[0023] [Protective Layer] The aforementioned protective layer can be formed from any suitable film that can be used as a protective layer for a polarizing element. Specific examples of materials that are the main components of the film include: cellulose resins such as triacetyl cellulose (TAC), polyester resins, polyvinyl alcohol resins, polycarbonate resins, polyamide resins, polyimide resins, polyether resins, polyurethane resins, polystyrene resins, polynorcamphene resins, polyolefin resins, (meth)acrylic acid resins, acetate resins, and other resins.

[0024] The thickness of the protective layer is preferably 5 μm to 80 μm, more preferably 10 μm to 40 μm, and even more preferably 15 μm to 35 μm.

[0025] In one embodiment, the protective layer 30 disposed on the side of the polarizing element 30 where the multilayer film 20 is not disposed is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane phase difference Re(550) is 0 nm to 10 nm and the phase difference Rth(550) in the thickness direction is -10 nm to +10 nm.

[0026] [Laminated Film] The laminated film described above has a substrate and a surface treatment layer formed on the substrate. The substrate functions as a protective layer for the polarizing element, as detailed above. In embodiments of the present invention, the polarizing plate is typically disposed on the viewing side of an image display device, and the laminated film is disposed on the viewing side. In one embodiment, the surface treatment layer of the laminated film is located on the outermost surface of the image display device. Therefore, it is preferable to form the surface treatment layer on the substrate (the protective layer on the viewing side). Examples of surface treatments include: hard coating (HC) treatment, anti-reflective treatment, anti-adhesion treatment, anti-glare treatment, and anti-fouling treatment.

[0027] The haze on the surface treatment layer side of the laminated film is preferably 1% or more, more preferably 1.5% or more, and even more preferably 2% or more. With this type of laminated film, the generation of superimposed lines can be suppressed. Superimposed lines are a phenomenon where light interferes according to wavelength, causing rainbow patterns to be projected onto the image surface; the larger the image, the easier it is to perceive superimposed lines. On the other hand, the haze on the surface treatment layer side of the laminated film is preferably 13% or less, more preferably 10% or less, and even more preferably 7% or less. With this type of laminated film, the generation of white blur, which appears as if the image surface is blurred and white, can be suppressed. White blur tends to be easily perceived in bright room environments.

[0028] The reflectivity of the surface treatment layer side of the laminated film is preferably 2% or less, and more preferably 1.6% or less. With this type of laminated film, it is possible to suppress the image reflected onto the screen due to external light such as fluorescent lamps or sunlight, which would reduce visibility. Such reflection tends to be easily visible in outdoor environments.

[0029] In one embodiment, the surface treatment layer has an anti-glare layer and an anti-reflective layer sequentially from the substrate side. The anti-glare layer typically includes a resin and a filler. Specifically, by containing a filler in the resin, a fine uneven shape is formed on the surface of the obtained layer (anti-glare layer), thereby achieving anti-glare properties.

[0030] For example, the anti-glare layer can be typically obtained by drying and curing a coating film obtained by applying an anti-glare layer forming material to the aforementioned substrate. The anti-glare layer forming material typically includes a curable compound as a layer forming component. Examples of curing mechanisms for the curable compound include thermosetting and photosetting types. Examples of curable compounds include monomers, oligomers, and prepolymers. It is preferable to use a multifunctional monomer or oligomer as the curable compound. Examples of multifunctional monomers or oligomers include monomers or oligomers having two or more (meth)acrylic groups, oligomers of urethane (meth)acrylates or urethane (meth)acrylates, epoxy monomers or oligomers, and silicone monomers or oligomers.

[0031] The refractive index of the above-mentioned filler is, for example, 1.3 or more and 1.8 or less, preferably 1.4 or more and 1.6 or less.

[0032] The fillers described above can be inorganic particles, organic particles, or a combination of inorganic and organic particles. Examples of inorganic particles include: silicon oxide particles, titanium oxide particles, aluminum oxide particles, zinc oxide particles, tin oxide particles, calcium carbonate particles, barium sulfate particles, talc particles, kaolin particles, and calcium sulfate particles. Examples of organic particles include: polymethyl methacrylate resin powder (PMMA particles), silica resin powder, polystyrene resin powder, polycarbonate resin powder, styrene acrylic resin powder, benzoguanamine resin powder, melamine resin powder, polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, and polyvinyl fluoride resin powder. One of these particles can be used alone, or two or more can be used in combination.

[0033] In one embodiment, the filler content relative to 100 parts by weight of resin is, for example, 1 part by weight or more and 3 parts by weight, or 1.5 parts by weight or more and 2.5 parts by weight or less. In another embodiment, the filler content relative to 100 parts by weight of resin is, for example, 5 parts by weight or more and 7.5 parts by weight, or 6 parts by weight or more and 7 parts by weight or less.

[0034] The thickness of the anti-glare layer is preferably 4 μm to 12 μm, more preferably 6 μm to 9 μm. Furthermore, the same solvent and method as those used in the anti-glare layer forming liquid can be used as the solvent that can be included in the anti-glare layer forming material and as the method for applying, drying and curing the anti-glare layer forming material.

[0035] The aforementioned anti-reflective layer can reduce the reflection of the surface of the anti-glare layer. The anti-reflective layer can be obtained, for example, by applying an anti-reflective layer forming liquid to the aforementioned anti-glare layer and allowing the resulting coating to dry and harden. The anti-reflective layer forming liquid may, for example, contain a curing compound, a fluorinated additive, hollow particles, and a solvent, and may be obtained by mixing these components.

[0036] Examples of curing mechanisms for the curing compounds contained in the coating liquid for forming the antireflective layer include thermosetting and photocuring types. Examples of curing compounds include compounds having at least one of acrylate or methacrylate groups, such as oligomers or prepolymers of acrylates or methacrylates of polyfunctional compounds like silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and polyols. These compounds can be used alone or in combination of two or more.

[0037] For example, a reactive diluent having at least one of acrylate or methacrylate groups can be used in the above-mentioned curing compound. The reactive diluent may be, for example, the reactive diluent disclosed in Japanese Patent Application Publication No. 2008-88309, including monofunctional acrylates, monofunctional methacrylates, polyfunctional acrylates, and polyfunctional methacrylates. From the viewpoint of obtaining excellent hardness, it is preferable to use trifunctional or higher acrylates or trifunctional or higher methacrylates as the reactive diluent. Examples of reactive diluents include, for example, butanediol glycerol ether diacrylate, acrylates of isocyanuric acid, and methacrylates of isocyanuric acid. One of these reactive diluents may be used alone, or two or more may be used in combination. To cure the above-mentioned curing compound, a curing agent may be used, for example. As a curing agent, a known polymerization initiator (e.g., a thermal polymerization initiator, a photopolymerization initiator, etc.) may be used.

[0038] The aforementioned fluorinated additive may be, for example, a fluorinated organic compound or a fluorinated inorganic compound. Examples of fluorinated organic compounds include: fluorinated antifouling coatings, fluorinated acrylic compounds, and fluorinated / silicone acrylic compounds. Commercially available products may be used as fluorinated organic compounds. Specific examples of commercially available products include "KY-1203" manufactured by Shin-Etsu Chemical Industry Co., Ltd., and "Megafac" manufactured by DIC Co., Ltd. The content of the fluorinated additive relative to 100 parts by weight of the aforementioned curing compound may be, for example, 0.05 parts by weight or more, 0.1 parts by weight or more, 0.15 parts by weight or more, 0.20 parts by weight or more, or 0.25 parts by weight or more, or may be less than 20 parts by weight, less than 15 parts by weight, less than 10 parts by weight, less than 5 parts by weight, or less than 3 parts by weight.

[0039] As the aforementioned hollow particles, silicon dioxide particles, acrylic acid particles, and acrylic-styrene copolymer particles can be used, for example. Commercially available hollow silicon dioxide particles can be used (e.g., products manufactured by Nippon Chemi-Conductivity Co., Ltd. under the trade names "Thrulya 5320" and "Thrulya 4320"). The weight-average particle size of the hollow particles can be, for example, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, or 70 nm or more, or 150 nm or less, 140 nm or less, 130 nm or less, 120 nm or less, or 110 nm or less. The shape of the hollow particles is not particularly limited, but a generally spherical shape is preferred. Specifically, the aspect ratio of the hollow particles is preferably 1.5 or less.

[0040] The content of hollow particles relative to 100 parts by weight of the aforementioned curing compound (cured resin component) is, for example, 11 parts by weight or more, or 12 parts by weight or more, or even 15 parts by weight or more. Within this range, sufficient anti-reflective function can be obtained. On the other hand, the content of hollow particles relative to 100 parts by weight of the aforementioned curing compound (cured resin component) is, for example, 40 parts by weight or less, or 30 parts by weight or less, or even 24 parts by weight or less. In one embodiment, the haze can be adjusted by adjusting the content of hollow particles in the anti-reflective layer and the type or content of filler contained in the aforementioned anti-glare layer.

[0041] Any suitable solvent may be used as the solvent described above. Examples of solvents include: alcohols such as methanol, ethanol, isopropanol, butanol, TBA (tert-butanol), and 2-methoxyethanol; ketones such as acetone, methyl ethyl ketone, MIBK (methyl isobutyl ketone), and cyclopentanone; esters such as methyl acetate, ethyl acetate, butyl acetate, and PMA (propylene glycol monomethyl ether acetate); ethers such as diisopropyl ether and propylene glycol monomethyl ether; glycols such as ethylene glycol and propylene glycol; cellosolvers such as ethyl cellosolvers and butyl cellosolvers; aliphatic hydrocarbons such as hexane, heptane, and octane; and aromatic hydrocarbons such as benzene, toluene, and xylene. One of these solvents may be used alone, or two or more may be used in combination. Regarding the solvent content, for example, relative to the total weight of the coating liquid for forming the antireflective layer, the weight of the solid component may be 0.1% by weight or more, 0.3% by weight or more, 0.5% by weight or more, 1.0% by weight or more, or 1.5% by weight or more, or it may be less than 20% by weight, less than 15% by weight, less than 10% by weight, less than 5% by weight, or less than 3% by weight.

[0042] The coating method for the above-mentioned antireflective layer forming coating liquid can be, for example, a known coating method such as jet coating, mold coating, spin coating, spray coating, gravure coating, roller coating, or bar coating. The drying temperature of the above-mentioned coating film is, for example, 30°C to 200°C, and the drying time is, for example, 30 seconds to 90 seconds. The above-mentioned coating film can be cured, for example, by heating or light irradiation (typically ultraviolet irradiation). As a light source for light irradiation, a high-pressure mercury lamp can be used, for example. The amount of ultraviolet irradiation is preferably 50 mJ / cm2 to 500 mJ / cm2, calculated as the cumulative exposure at an ultraviolet wavelength of 365 nm.

[0043] The thickness of the anti-reflective layer is preferably 0.1 μm to 2 μm, and more preferably 0.1 μm to 1 μm.

[0044] The thickness of the surface treatment layer is, for example, 1 μm to 20 μm, preferably 4 μm to 14 μm, and even more preferably 6 μm to 10 μm.

[0045] [Phase Retardation Layer] The aforementioned phase retardation layer may have an in-plane phase retardation. In one embodiment, the phase retardation layer can function as a λ / 4 plate. Specifically, the in-plane phase retardation Re(550) of the phase retardation film is, for example, 100 nm to 190 nm, preferably 110 nm to 180 nm, more preferably 120 nm to 170 nm, further preferably 130 nm to 160 nm, and even more preferably 135 nm to 155 nm. The composition of the phase retardation layer is not particularly limited; for example, it may be composed of a resin film or an alignment-cured layer of a liquid crystal compound (liquid crystal alignment-cured layer). Here, "alignment-cured layer" refers to a layer in which the liquid crystal compound is aligned along a specific direction within the layer, and its alignment state is fixed. Furthermore, "alignment-cured layer" includes the concept of an alignment-cured layer obtained by curing liquid crystal monomers. [Example]

[0046] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. Furthermore, the thickness, reflectance, haze and transmittance are values ​​obtained by the following measurement methods. Also, unless otherwise explicitly stated, "parts" and "%" in the examples and comparative examples are based on weight. 1. Thickness of 10 μm or less was measured using a scanning electron microscope (manufactured by Nippon Electronics Co., Ltd., product name "JSM-7100F"). Thickness of more than 10 μm was measured using a digital micrometer (manufactured by Anritsu Co., Ltd., product name "KC-351C"). 2. Haze was measured according to JIS 7136 using a haze meter (manufactured by Murakami Color Science Research Institute Co., Ltd., product name "HN-150"). When measuring the reflectance of the surface treatment layer side of the laminated film, the laminated film was adhered to a black acrylic plate with an adhesive as a sample for measurement. 3. Reflectance was measured using a UV-Vis-IR spectrophotometer (manufactured by Hitachi High-Tech, product name "U-4100"). When measuring the reflectance of the surface treatment layer side of the laminated film, the laminated film was adhered to a black acrylic plate using an adhesive, serving as the sample for measurement. Measurements were performed at wavelengths from 380 nm to 780 nm. 4. Transmittance was measured using a UV-Vis spectrophotometer (manufactured by Japan Spectrophotometer Co., Ltd., "V7100"). Furthermore, transmittance was measured using a 2-degree field of view (C-light source) of JIS Z8701 and the Y value was corrected for visual sensitivity.

[0047] [Example 1] (Fabrication of Polarizing Element) A long roll of 30 μm thick polyvinyl alcohol (PVA) resin film (manufactured by Kuraray, product name "PE3000") was uniaxially stretched along its length by 5.9 times in the length direction using a roll stretching machine. Simultaneously, swelling, dyeing, crosslinking, and washing processes were performed sequentially, followed by drying to produce a 12 μm thick polarizing element. The swelling process was carried out in pure water at 20°C while stretching to 2.2 times. Next, the dyeing process was carried out in an aqueous solution at 30°C with an iodine to potassium iodide weight ratio of 1:7 adjusted to achieve the desired monomer transmittance of the obtained polarizing element, while stretching to 1.4 times. Next, the crosslinking process employed a two-stage crosslinking process. The first stage of crosslinking was carried out in an aqueous solution containing boric acid and potassium iodide dissolved at 40°C while stretching to 1.2 times. The first stage crosslinking treatment aqueous solution contained 5.0 wt% boric acid and 3.0 wt% potassium iodide. The second stage crosslinking treatment involved processing in an aqueous solution containing dissolved boric acid and potassium iodide at 65°C, extending the crosslinking by 1.6 times. The second stage crosslinking treatment aqueous solution contained 4.3 wt% boric acid and 5.0 wt% potassium iodide. Next, a washing treatment was performed in an aqueous solution of potassium iodide at 20°C. The washing treatment aqueous solution contained 2.6 wt% potassium iodide. Finally, a drying treatment at 70°C for 5 minutes was performed to obtain the polarizing element.

[0048] (Fabrication of laminated film) A surface treatment layer is formed on a TAC film with a thickness of 25 μm in the following order to obtain a laminated film (haze: 2.5%, reflectivity: 1.5%).

[0049] (Formation of Surface Treatment Layer) 1. Preparation for Formation of Anti-Glare Layer (Anti-Glare Hard Coating) 80 parts by weight of UV-curable urethane acrylate resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "UV1700B", 100% solid content) and 20 parts by weight of polyfunctional acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat#300", 100% solid content) with pentaerythritol triacrylate as the main component. Relative to 100 parts by weight of the resin solids content of the mixture, 2 parts by weight of the mixed cross-linked polymethyl methacrylate particles (manufactured by Sekisui Chemicals Co., Ltd., trade name "Techpolymer", weight average particle size: 5 μm, refractive index: 1.51), 0.4 parts by weight of synthetic bentonite (manufactured by Co-op Chemical Co., Ltd., trade name "Lucentite SAN") as organoclay (thixotropic agent), 3 parts by weight of photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907"), and 0.05 parts by weight of leveling agent (manufactured by DIC Co., Ltd., trade name "PC4100", solids content 10%). Here, the organoclay is diluted with toluene to a solids content of 6% before use. The obtained mixture is diluted with a toluene / cyclopentanone (CPN) mixed solvent (weight ratio 80 / 20) to a solids content concentration of 40% by weight to prepare an anti-glare layer forming material (coating liquid).

[0050] The obtained anti-glare layer forming material (coating liquid) was applied to a TAC film (25 μm thick, manufactured by Fujifilm Corporation, trade name "TJ25UL") using a bar coater. Subsequently, after the coating was dried by heating at 95°C for 1 minute, the coating was irradiated with ultraviolet light using a high-pressure mercury lamp at a cumulative light intensity of 300 mJ / cm2 to form an anti-glare layer with a thickness of 6.5 μm.

[0051] 2. The antireflective layer is formed by mixing a multifunctional acrylate (manufactured by Osaka Organic Chemicals Co., Ltd., trade name "Viscoat #300", solid content 100 wt%) with pentaerythritol triacrylate as the main component, 100 parts by weight of hollow nano silica particles (manufactured by Nichibukai Chemicals Co., Ltd., trade name "Thrulya 5320", solid content 20 wt%, weight average particle size 75 nm), 12 parts by weight of fluorine-containing additive (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KY-1203", solid content 20 wt%), and 3 parts by weight of photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907", solid content 100 wt%). A mixed solvent, consisting of TBA, MIBK, and PMA mixed in a weight ratio of 60:25:15, is added to the mixture to bring the total solid content to 4% by weight. The mixture is then stirred to prepare an antireflective coating solution.

[0052] The obtained anti-reflective layer forming solution was applied to the above-mentioned anti-glare layer using a wire bar coater. The applied solution was heated at 80°C for 1 minute to dry and form a coating film. The obtained coating film was then irradiated with ultraviolet light with a cumulative light intensity of 300 mJ / cm2 using a high-pressure mercury lamp to perform a curing treatment, forming an anti-reflective layer with a thickness of 0.1 μm. Thus, a surface treatment layer was formed.

[0053] (Fabrication of Polarizing Plate) A multilayer film is bonded to one side of the obtained polarizing element using a UV-curable adhesive, with the TAC film serving as the polarizing element side. A 25 μm thick TAC film is bonded to the other side of the polarizing element using a UV-curable adhesive to obtain a multilayer (transmittance: 46.0%). Then, a phase retardation film (polycarbonate resin film, thickness: 50 μm, Re(550): 147 nm, manufactured by Teijin Co., Ltd., product name "Pureace RM") is bonded to a 12 μm thick acrylic adhesive layer, and then a 15 μm thick acrylic adhesive layer is formed to obtain a polarizing plate.

[0054] [Example 2] In the fabrication of the polarizing element, the iodine concentration during dyeing was changed, and the surface treatment layer was formed in the following order. Otherwise, the operation was the same as in Example 1 to obtain the polarizing plate.

[0055] (Formation of Surface Treatment Layer) 1. Formation of Anti-Glare Layer (Anti-Glare Hard Coating) 100 parts by weight of UV-curable urethane acrylate resin (manufactured by DIC Corporation, "UNIDIC 17-806"), 6.5 parts by weight of silica particles (manufactured by FUJI SILYSIA CHEMICAL LTD., "SYLOPHOBIC 702"), 6.5 parts by weight of silica particles (manufactured by FUJI SILYSIA CHEMICAL LTD., "SYLOPHOBIC 100"), and 2.5 parts by weight of synthetic bentonite (manufactured by Co-op Chemical Corporation, trade name "Lucentite SAN") as organic clay (tackifier), and then 5 parts by weight of photopolymerization initiator (manufactured by BASF Corporation, "OMNIRAD184") and 0.5 parts by weight of leveling agent (manufactured by DIC Corporation, "Megafac F-556") are added and mixed. A material (coating solution) for forming an anti-glare layer is prepared by diluting the mixture with toluene to achieve a solid content concentration of 30% by weight.

[0056] The obtained anti-glare layer forming material (coating liquid) was applied to a TAC film (25 μm thick, manufactured by Fujifilm Corporation, trade name "TJ25UL") using a bar coater. Subsequently, after the coating was dried by heating at 110°C for 1 minute, the coating was irradiated with ultraviolet light using a high-pressure mercury lamp to achieve a cumulative light intensity of 300 mJ / cm2, thereby forming an anti-glare layer with a thickness of 8.0 μm.

[0057] 2. The antireflective layer is formed by mixing a multifunctional acrylate (manufactured by Osaka Organic Chemicals Co., Ltd., trade name "Viscoat #300", solid content 100 wt%) with pentaerythritol triacrylate as the main component, 100 parts by weight, hollow nano silica particles (manufactured by Nichibukai Chemicals Co., Ltd., trade name "Thrulya 5320", solid content 20 wt%, weight average particle size 75 nm) 180 parts by weight, fluorine-containing additive (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KY-1203", solid content 20 wt%) 12 parts by weight, and a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907", solid content 100 wt%) 3 parts by weight. A mixed solvent, consisting of TBA, MIBK, and PMA mixed in a weight ratio of 60:25:15, is added to the mixture to bring the total solid content to 4% by weight. The mixture is then stirred to prepare an antireflective coating solution.

[0058] The obtained anti-reflective layer forming coating solution was applied to the above-mentioned anti-glare layer using a wire bar coater. The applied coating solution was heated at 80°C for 1 minute to dry and form a coating film. The obtained coating film was then irradiated with ultraviolet light with a cumulative light intensity of 300 mJ / cm2 using a high-pressure mercury lamp to perform a curing treatment, forming an anti-reflective layer with a thickness of 0.1 μm. Thus, a surface treatment layer was formed.

[0059] [Comparative Example 1] In the fabrication of the polarizing element, the iodine concentration during dyeing was changed, and the surface treatment layer was formed in the following order. Otherwise, the operation was the same as in Example 1 to obtain the polarizing plate.

[0060] (Formation of Surface Treatment Layer) 100 parts by weight of UV-curable acrylic resin (manufactured by DIC Corporation, trade name "LUXYDIR 17-806", solids content 80%), 3 parts by weight of photopolymerization initiator (manufactured by BASF Corporation, trade name "OMNIRAD907"), and 0.01 parts by weight of leveling agent (manufactured by DIC Corporation, trade name "PC4100", solids content 10%) were mixed. The obtained mixture was diluted with a PGM (propylene glycol monomethyl ether) / cyclopentanone mixed solvent (weight ratio 63 / 37) to a solids content concentration of 36% to prepare a coating liquid for hard coating formation.

[0061] The obtained hard coating forming solution was applied to a TAC film (25 μm thick, manufactured by Fujifilm Corporation, trade name "TJ25UL") using a wire bar coater. Subsequently, after the coating was dried by heating at 95°C for 1 minute, the coating was irradiated with ultraviolet light using a high-pressure mercury lamp to achieve a cumulative light intensity of 300 mJ / cm2, thereby forming a 6.5 μm thick anti-glare hard coating (surface treatment layer).

[0062] [Comparative Example 2] In the fabrication of the polarizing element, the concentration of iodine during dyeing was changed, and the operation was otherwise the same as in Comparative Example 1 to obtain a polarizing plate.

[0063] [Comparative Example 3] In the fabrication of the polarizing element, the iodine concentration during dyeing was changed, and the surface treatment layer was formed in the following order. Otherwise, the operation was the same as in Example 1 to obtain the polarizing plate.

[0064] (Formation of Surface Treatment Layer) 100 parts by weight of a multifunctional acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat#300", solid content 100 wt%), with pentaerythritol triacrylate as the main component; 100 parts by weight of hollow nano-silica particles (manufactured by Nichibukai Chemical Industry Co., Ltd., trade name "Thrulya 5320", solid content 20 wt%, weight average particle size 75 nm), 12 parts by weight of a fluorine-containing additive (manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name "KY-1203", solid content 20 wt%); and 3 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907", solid content 100 wt%). A mixed solvent, consisting of TBA, MIBK, and PMA mixed in a weight ratio of 60:25:15, is added to the mixture to bring the total solid content to 4% by weight. The mixture is then stirred to prepare an antireflective coating solution.

[0065] The obtained antireflective layer forming coating solution was applied to a TAC film (25 μm thick, manufactured by Fujifilm Corporation, trade name "TJ25UL") using a wire bar coater. The coating solution was heated at 80°C for 1 minute to dry and form a coating film. The obtained coating film was then irradiated with ultraviolet light with a cumulative light intensity of 300 mJ / cm2 using a high-pressure mercury lamp to perform a curing treatment, forming an antireflective layer (surface treatment layer) with a thickness of 0.1 μm.

[0066] [Comparative Example 4] In the fabrication of the polarizing element, the concentration of iodine during dyeing was changed, and the operation was otherwise the same as in Example 1 to obtain a polarizing plate.

[0067] [Comparative Example 5] In the fabrication of the polarizing element, the iodine concentration during dyeing was changed, and the surface treatment layer was formed in the following order. Otherwise, the operation was the same as in Example 1 to obtain the polarizing plate.

[0068] (Formation of Surface Treatment Layer) 1. Formation of Anti-Glare Layer (Anti-Glare Hard Coating): 100 parts by weight of UV-curable urethane acrylate resin (manufactured by DIC Corporation, "UNIDIC 17-806"), 7 parts by weight of silica particles (manufactured by FUJI SILYSIA CHEMICAL LTD., "SYLOPHOBIC 702"), 6.5 parts by weight of silica particles (manufactured by FUJI SILYSIA CHEMICAL LTD., "SYLOPHOBIC 100"), 5 parts by weight of photopolymerization initiator (manufactured by BASF Corporation, "OMNIRAD184"), and 0.5 parts by weight of leveling agent (manufactured by DIC Corporation, "MegafacF-556") are mixed. The mixture is diluted with toluene to achieve a solid content concentration of 30% by weight to prepare an anti-glare layer forming material (coating liquid).

[0069] The obtained anti-glare layer forming material (coating liquid) was applied to a TAC film (25 μm thick, manufactured by Fujifilm Corporation, trade name "TJ25UL") using a bar coater. Subsequently, after the coating was dried by heating at 110°C for 1 minute, the coating was irradiated with ultraviolet light using a high-pressure mercury lamp to achieve a cumulative light intensity of 300 mJ / cm2, thereby forming an anti-glare layer with a thickness of 5.0 μm.

[0070] 2. The antireflective layer is formed by mixing a multifunctional acrylate (manufactured by Osaka Organic Chemicals Co., Ltd., trade name "Viscoat #300", solid content 100 wt%) with pentaerythritol triacrylate as the main component, 100 parts by weight, hollow nano silica particles (manufactured by Nichibukai Chemicals Co., Ltd., trade name "Thrulya 5320", solid content 20 wt%, weight average particle size 75 nm) 60 parts by weight, fluorine-containing additive (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KY-1203", solid content 20 wt%), and a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907", solid content 100 wt%) 3 parts by weight. A mixed solvent, consisting of TBA, MIBK, and PMA mixed in a weight ratio of 60:25:15, is added to the mixture to bring the total solid content to 4% by weight. The mixture is then stirred to prepare an antireflective coating solution.

[0071] The obtained anti-reflective layer forming solution was applied to the above-mentioned anti-glare layer using a wire bar coater. The applied solution was heated at 80°C for 1 minute to dry and form a coating film. The obtained coating film was then irradiated with ultraviolet light with a cumulative light intensity of 300 mJ / cm2 using a high-pressure mercury lamp to perform a curing treatment, forming an anti-reflective layer with a thickness of 0.1 μm. Thus, a surface treatment layer was formed.

[0072] [Comparative Example 6] In the fabrication of the polarizing element, the iodine concentration during dyeing was changed, and the surface treatment layer was formed in the following order. Otherwise, the operation was the same as in Example 1 to obtain the polarizing plate.

[0073] (Formation of Surface Treatment Layer) 100 parts by weight of a multifunctional acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat #300", solid content 100 wt%), with pentaerythritol triacrylate as the main component; 70 parts by weight of hollow nano-silica particles (manufactured by Nichibukai Chemical Industry Co., Ltd., trade name "Thrulya 5320", solid content 20 wt%, weight average particle size 75 nm); 12 parts by weight of a fluorine-containing additive (manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name "KY-1203", solid content 20 wt%); and 3 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD907", solid content 100 wt%). A mixed solvent, consisting of TBA, MIBK, and PMA mixed in a weight ratio of 60:25:15, is added to the mixture to bring the total solid content to 4% by weight. The mixture is then stirred to prepare an antireflective coating solution.

[0074] The obtained antireflective layer forming coating solution was applied to a TAC film (25 μm thick, manufactured by Fujifilm Corporation, trade name "TJ25UL") using a wire bar coater. The coating solution was heated at 80°C for 1 minute to dry and form a coating film. The obtained coating film was then irradiated with ultraviolet light with a cumulative light intensity of 300 mJ / cm2 using a high-pressure mercury lamp to perform a curing treatment, forming an antireflective layer (surface treatment layer) with a thickness of 0.1 μm.

[0075] The examples and comparative examples were evaluated as follows. The evaluation results are summarized in Table 1. <Evaluation> 1. Overlay: The polarizing plate obtained was observed visually from the surface treatment layer side under fluorescent lighting to confirm the occurrence of overlay (rainbow pattern). 2. White Blur: The polarizing plate obtained was observed visually from the surface treatment layer side under bright lighting to confirm the occurrence of white blur caused by diffuse reflection of light. 3. Reflection: The polarizing plate obtained was observed visually from the surface treatment layer side under fluorescent lighting to confirm the occurrence of reflection. 4. Image Retention: After removing the front surface glass and polarizing plate of the "Galaxy A41" manufactured by Samsung, which is equipped with an organic EL panel, the obtained polarizing plate was bonded to the surface of the organic EL panel to obtain a test image. As shown in Figure 3, specific text was displayed in black at the upper left corner of the obtained test screen. The central point was used as the measurement point. The brightness of the measurement point was measured using a Topcon SR-UL1R microscope to adjust the display of the test screen to achieve a brightness of 400 cd / m² (comparable to outdoor brightness). After being lit up for 30 hours in this state, the brightness of the measurement point was measured, and the brightness reduction rate was calculated. Furthermore, after being lit up, the entire screen was displayed in white, and the test screen was observed visually.

[0076] [Table 1] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Haze (%) 2.5 12.0 0.5 0.5 0.3 2.5 25.0 0.4 Reflectance (%) 1.5 0.9 6.0 6.0 1.0 1.5 2.2 1.9 Transmission rate (%) 46.0 46.0 45.0 46.0 44.1 45.0 44.0 44.0 Layered patterns good good bad bad bad good Very good bad White blur Very good good Very good Very good Very good Very good bad Very good Image good good bad bad good good bad good Image afterimage Brightness (cd / m 2 ) 397 398 395 397 394 395 394 393 Reduction rate (%) 0.7 0.6 1.2 0.7 1.6 1.3 1.6 1.7 Visual evaluation good good bad good bad bad bad bad

[0077] The embodiment excels in all aspects of overlay, white blur, ingress, and image afterimage, and is suitable for use, for example, in laptop computers. In Comparative Examples 1 and 3-6, where the brightness reduction rate exceeds 1%, the brightness of the area other than the text displayed in the upper left corner is reduced, and the displayed text appears to float in white. [Industrial Applicability]

[0078] The polarizing plate obtained by means of the embodiments of the present invention can be suitably used as a polarizing plate for an image display device. Examples of image display devices include organic EL display devices, inorganic EL display devices, and liquid crystal display devices. [Simplified Explanation of the Diagram]

[0008] FIG1 is a schematic cross-sectional view showing the general configuration of a polarizing plate according to one embodiment of the present invention. FIG2 is a schematic cross-sectional view showing the state in which a polarizing plate is disposed on an organic EL panel in an organic EL display device according to one embodiment of the present invention. FIG3 is a diagram illustrating a method for evaluating image retention.

Claims

1. A polarizing plate comprising: a laminated film having a substrate and a surface treatment layer, and a polarizing element disposed on the substrate side of the laminated film, wherein the surface treatment layer has an anti-glare layer and an anti-reflection layer sequentially from the substrate side, the anti-reflection layer is directly formed on the anti-glare layer, the anti-reflection layer is a single layer, the reflectivity on the surface treatment layer side is 2% or less, the haze on the surface treatment layer side is 1% to 13%, the transmittance of the polarizing plate is 45.5% or more, and the polarizing plate is used in an organic EL panel.

2. The polarizing plate of claim 1, wherein the antireflective layer comprises a resin component and hollow particles, and the antireflective layer comprises 11 or more parts by weight of the hollow particles relative to 100 parts by weight of the resin component.

3. The polarizing plate of claim 1, wherein the antireflective layer comprises a resin component and hollow particles, and the antireflective layer comprises hollow particles in an amount of 40 parts by weight or less relative to 100 parts by weight of the resin component.

4. The polarizing plate of claim 1 further has a phase retardation layer, wherein the in-plane phase retardation layer has an in-plane phase retardation Re(550) of 100 nm to 190 nm.

5. An image display device comprising: an image display panel body, and a polarizing plate disposed on the viewing side of the image display panel body as claimed in any one of claims 1 to 4.

6. The image display device of claim 5, wherein the polarizing plate is located on the outermost surface of the viewing side.

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