JP7577413B2 - Polarizer protective film, polarizing plate and image display device - Google Patents

Description

The present invention relates to a polarizer protective film and a polarizing plate and an image display device using the polarizer protective film.

In a liquid crystal display device, which is one of the representative image display devices, polarizing plates are attached to both sides of a liquid crystal cell due to its image formation method. A polarizing plate usually includes a polarizer and a protective film that protects the polarizer, and from the viewpoint of improving the viewing angle, it can be used as a polarizing plate with a retardation layer that further includes a retardation layer. In addition, an organic electroluminescence (EL) display device is provided with a circular polarizing plate on the viewing side to prevent problems such as external light reflection and background reflection caused by the high reflectivity of the organic EL cell. A typical circular polarizing plate is known to be one in which a polarizer and a retardation layer (typically a λ/4 plate) are laminated so that the slow axis of the retardation layer forms an angle of about 45° with the absorption axis of the polarizer.

It has been proposed that the provision of a colored layer on the polarizing plate can provide high polarization characteristics and good reflection characteristics over a wide band (e.g., Patent Document 1, Patent Document 2, etc.). However, polarizing plates provided with a colored layer may have poor durability in a humid environment.

As mentioned above, it is known that the viewing angle of an image display device can be improved by using a polarizing plate with a retardation layer, but in such image display devices, color differences (color unevenness) may be visible on the display screen.

WO2018/110503 JP 2018-72712 A

The present invention has been made to solve the above-mentioned problems in the conventional art, and its main objective is to provide a polarizing plate with improved durability in a humid environment. Another objective is to improve color unevenness on the display screen.

According to one aspect of the present invention, there is provided a polarizer protective film which is a resin film containing a dye and has a water absorption rate of 3.0% or less.
In one embodiment, the polarizer protective film contains at least one resin selected from the group consisting of polyethylene terephthalate-based resins, acrylic-based resins, polycarbonate-based resins, and cycloolefin-based resins.
In one embodiment, the polarizer protective film has a front retardation Re(550) of 90 nm to 160 nm or 200 nm to 320 nm.
In one embodiment, the polarizer protective film is a stretched resin film.
In one embodiment, the polarizer protective film has a slow axis in a direction of 20° to 60° or 110° to 150° clockwise when the longitudinal direction is taken as 0°.
In one embodiment, the polarizer protective film has a haze of 3% or less.
According to another aspect of the present invention, there is provided a polarizing plate having a polarizer and the above-mentioned polarizer protective film arranged on at least one side of the polarizer, wherein the change in visible light transmittance after 96 hours in an environment of 65°C and 90% RH is 10% or less.
In one embodiment, in the polarizing plate, the polarizer and the polarizer protective film are bonded to each other via an ultraviolet-curable adhesive.
In one embodiment, the polarizing plate has a visible light transmittance of 20% or more.
In one embodiment, the polarizer protective film has a front retardation Re(550) of 90 nm to 160 nm, and the angle between the absorption axis direction of the polarizer and the slow axis of the polarizer protective film is 35° to 55° in a clockwise or counterclockwise direction.
In one embodiment, the polarizer has a long shape, the polarizer protective film is a long obliquely stretched film, and the polarizer and the polarizer protective film are attached to each other with their longitudinal directions aligned.
According to another aspect of the present invention, there is provided an image display device including the above polarizing plate.

According to the present invention, a polarizing plate with improved durability in a humid environment can be obtained by using a polarizer protective film that is a resin film containing a dye and has a water absorption rate of 3.0% or less. In addition, by arranging the polarizing plate so that the polarizer protective film is closer to the optical cell than the polarizer, an image display device with improved color unevenness on the display screen can be obtained.

1 is a schematic cross-sectional view illustrating a polarizing plate according to one embodiment of the present invention. 1 is a schematic cross-sectional view illustrating a polarizing plate according to one embodiment of the present invention. 1 is a schematic cross-sectional view illustrating a polarizing plate according to one embodiment of the present invention.

The following describes embodiments of the present invention, but the present invention is not limited to these embodiments.

(Definition of terms and symbols)
The terms and symbols used in this specification are defined as follows.
(1) Refractive index (nx, ny, nz)
"nx" is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction), "ny" is the refractive index in the direction perpendicular to the slow axis in the plane (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 retardation measured with light having a wavelength of λ nm at 23° C. For example, "Re(550)" is the in-plane retardation measured with light having a wavelength of 550 nm at 23° C. Re(λ) is calculated by the formula: Re=(nx-ny)×d, where d (nm) is the thickness of the layer (film).
(3) Retardation in the thickness direction (Rth)
"Rth(λ)" is the retardation in the thickness direction measured with light having a wavelength of λ nm at 23° C. For example, "Rth(550)" is the retardation in the thickness direction measured with light having a wavelength of 550 nm at 23° C. Rth(λ) is calculated by the formula: Rth=(nx-nz)×d, where d (nm) is the thickness of the layer (film).
(4) Nz Coefficient The Nz coefficient is calculated by Nz=Rth/Re.

A. Polarizer Protective Film The polarizer protective film according to the embodiment of the present invention is a resin film containing a dye and has a water absorption rate of 3.0% or less. Conventional polarizing plates provided with a colored layer have large changes in physical properties due to the environment, and problems such as dye loss can occur in a humid environment. However, by making the polarizer protective film contain a dye and setting its water absorption rate to a predetermined value or less, a polarizing plate in which changes in physical properties in a humid environment are suppressed can be obtained.

The water absorption rate of the polarizer protective film is typically 3.0% or less, preferably 2.5% or less, more preferably 2.0% or less, and even more preferably 0% to 1.5%. When the water absorption rate of the polarizer protective film is within this range, pigment loss and other problems that may occur due to moisture entering and leaving the colored layer (polarizer protective film) are suppressed, and a polarizing plate in which changes in physical properties in a humid environment are suppressed can be obtained. The water absorption rate of the polarizer protective film can be determined in accordance with JIS K 7209.

A-1. Resin film As the resin forming the resin film, any suitable resin capable of realizing the desired water absorption rate is used. Specific examples of the resin forming the resin film include polyester-based resins such as polyethylene terephthalate, (meth)acrylic resins, cycloolefin-based resins such as polynorbornene, polycarbonate-based resins, cellulose-based resins, polyvinyl alcohol-based resins, polysulfone-based resins, and the like. Among them, polyethylene terephthalate resins, (meth)acrylic resins, polycarbonate-based resins, and cycloolefin-based resins are preferred because they have excellent stability in a humid environment (in other words, they can suitably achieve a water absorption rate of 3% or less). Note that "(meth)acrylic resin" refers to acrylic resins and/or methacrylic resins.

As the above-mentioned (meth)acrylic resin, a (meth)acrylic resin having a cyclic structure such as a lactone ring or a glutarimide ring in the main chain is preferably used. (Meth)acrylic resins having a glutarimide ring (hereinafter also referred to as glutarimide resins) are described, for example, in JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, JP-A-2006-328334, JP-A-2006-337491, JP-A-2006-337492, JP-A-2006-337493, JP-A-2006-337569, JP-A-2007-009182, JP-A-2009-161744, and JP-A-2010-284840. These descriptions are incorporated herein by reference.

As the polycarbonate resin, an aromatic polycarbonate is preferably used. Aromatic polycarbonate can be obtained, typically, by the reaction of a carbonate precursor with an aromatic dihydric phenol compound. Specific examples of carbonate precursors include phosgene, bischloroformates of dihydric phenols, diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, dinaphthyl carbonate, and the like. Among these, phosgene and diphenyl carbonate are preferred. Specific examples of aromatic dihydric phenol compounds include 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)butane, 2,2-bis(4-hydroxy-3,5-dipropylphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and the like. These may be used alone or in combination of two or more. Preferably, 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane are used. In particular, it is preferable to use 2,2-bis(4-hydroxyphenyl)propane and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane together.

The cycloolefin resin is not particularly limited as long as it is a resin having a monomer unit made of a cyclic olefin (cycloolefin), and may be, for example, a cycloolefin polymer (COP) or a cycloolefin copolymer (COC). A cycloolefin copolymer is a non-crystalline cyclic olefin resin that is a copolymer of a cyclic olefin and an olefin such as ethylene.

The cyclic olefins include polycyclic cyclic olefins and monocyclic cyclic olefins. Examples of polycyclic cyclic olefins include norbornene, methylnorbornene, dimethylnorbornene, ethylnorbornene, ethylidenenorbornene, butylnorbornene, dicyclopentadiene, dihydrodicyclopentadiene, methyldicyclopentadiene, dimethyldicyclopentadiene, tetracyclododecene, methyltetracyclododecene, dimethylcyclotetradodecene, tricyclopentadiene, and tetracyclopentadiene. Examples of monocyclic cyclic olefins include cyclobutene, cyclopentene, cyclooctene, cyclooctadiene, cyclooctatriene, and cyclododecatriene.

The above cycloolefin resins are also available as commercial products, such as Topas manufactured by Ticona, Arton manufactured by JSR, ZEONOR and ZEONEX manufactured by Zeon Corporation, and Apel manufactured by Mitsui Chemicals.

The resin film may be composed of a single layer or may have a multi-layer structure. A resin film having a multi-layer structure may be obtained using any suitable manufacturing method such as an extrusion method or a lamination method.

A-2. Dye Specific examples of the dye include anthraquinone-based, triphenylmethane-based, naphthoquinone-based, thioindigo-based, perinone-based, perylene-based, squarylium-based, cyanine-based, porphyrin-based, azaporphyrin-based, phthalocyanine-based, subphthalocyanine-based, quinizarin-based, polymethine-based, rhodamine-based, oxonol-based, quinone-based, azo-based, xanthene-based, azomethine-based, quinacridone-based, dioxazine-based, diketopyrrolopyrrole-based, anthrapyridone-based, isoindolinone-based, indanthrone-based, indigo-based, thioindigo-based, quinophthalone-based, quinoline-based, triphenylmethane-based dyes, etc. Dyes can be preferably used because they are well compatible with the resin film, which is the matrix.

In one embodiment, an anthraquinone-based, oxime-based, naphthoquinone-based, quinizarin-based, oxonol-based, azo-based, xanthene-based, or phthalocyanine-based dye is used as the dye. By using these dyes, it is possible to form a polarizer protective film that has a maximum absorption wavelength in the wavelength range of 440 nm to 510 nm.

In one embodiment, an indigo-based, rhodamine-based, quinacridone-based, or porphyrin-based dye is used as the pigment. By using these dyes, a polarizer protective film having a maximum absorption wavelength in the wavelength range of 560 nm to 610 nm can be formed.

Pigments may also be used as the dye. Specific examples of pigments include black pigments (carbon black, bone black, graphite, iron black, titanium black, etc.), azo pigments, phthalocyanine pigments, polycyclic pigments (quinacridone, perylene, perinone, isoindolinone, isoindoline, dioxazine, thioindigo, anthraquinone, quinophthalone, metal complex, diketopyrrolopyrrole, etc.), dye lake pigments, white/extender pigments (titanium oxide, zinc oxide, sulfide, etc.), and the like. zinc, clay, talc, barium sulfate, calcium carbonate, etc.), chromatic pigments (yellow lead, cadmium-based, chrome vermilion, nickel titanium, chrome titanium, yellow iron oxide, red iron oxide, zinc chromate, red lead, ultramarine, iron blue, cobalt blue, chrome green, chromium oxide, bismuth vanadate, etc.), luster pigments (pearl pigments, aluminum pigments, bronze pigments, etc.), fluorescent pigments (zinc sulfide, strontium sulfide, strontium aluminate, etc.), etc.

The content of the dye may be any appropriate ratio depending on the type of dye, the desired light absorption characteristics, etc. The content of the coloring material is, for example, 0.01 to 5.0 parts by weight, more preferably 0.05 to 2.0 parts by weight, and even more preferably 0.10 to 1.0 parts by weight, per 100 parts by weight of the matrix resin (resin film).

A-3. Optical properties of polarizer protective film In one embodiment, the polarizer protective film selectively absorbs light in a specific wavelength range (i.e., has a maximum absorption wavelength in a specific wavelength band). In another embodiment, the polarizer protective film functions to absorb all wavelengths in the visible light region. Preferably, the polarizer protective film selectively absorbs light in a specific wavelength range. A polarizer protective film that selectively absorbs light in a specific wavelength range can enhance the anti-reflection function while suppressing a decrease in visible light transmittance (i.e., a decrease in brightness). In addition, by adjusting the wavelength of the light to be absorbed, the reflection hue of the polarizing plate described in section B can be made neutral.

In one embodiment, the polarizer protective film has an absorption maximum wavelength in the wavelength bands ranging from 440 nm to 510 nm and/or 560 nm to 610 nm. A polarizer protective film having two or more absorption maximum wavelengths can be obtained, for example, by incorporating multiple types of dyes.

The transmittance of the polarizer protective film at the absorption maximum wavelength is preferably 0% to 80%, and more preferably 0% to 70%.

The visible light transmittance of the polarizer protective film is preferably 30% to 90%, and more preferably 30% to 80%.

The haze of the polarizer protective film is preferably 3% or less, more preferably 2% or less, even more preferably 1% or less, and even more preferably 0% to 0.5%. If the haze of the polarizer protective film is within this range, the polarization of the light passing through the polarizer protective film is maintained, and a polarizing plate with a high degree of polarization can be obtained.

In one embodiment, the polarizer protective film is optically anisotropic and can also function as a retardation film. The in-plane retardation Re(550) of the polarizer protective film that can function as a retardation film can be appropriately set depending on the purpose. For example, the polarizer protective film can function as a λ/4 plate or a λ/2 plate. Below, we will explain the case where the polarizer protective film is a λ/4 plate or a λ/2 plate.

When the polarizer protective film is a λ/4 plate, its in-plane retardation Re(550) is preferably 90 nm to 160 nm, more preferably 120 nm to 160 nm, and even more preferably 135 nm to 155 nm. A λ/4 plate typically has an index ellipsoid of nx>ny=nz or nx>ny>nz. In this specification, for example, "ny=nz" includes not only strictly equal but also substantially equal. The Nz coefficient is, for example, 0.9 to 2, preferably 1 to 1.5, and more preferably 1 to 1.3.

The thickness of the polarizer protective film that functions as a λ/4 plate can be set so that it can function most appropriately as a λ/4 plate. In other words, the thickness can be set so that a desired in-plane retardation is obtained. Specifically, the thickness is preferably 10 μm to 80 μm, more preferably 10 μm to 60 μm, and most preferably 30 μm to 50 μm.

The λ/4 plate may exhibit an inverse dispersion wavelength characteristic in which the phase difference value increases with the wavelength of the measurement light, a positive wavelength dispersion characteristic in which the phase difference value decreases with the wavelength of the measurement light, or a flat wavelength dispersion characteristic in which the phase difference value changes very little with the wavelength of the measurement light. As described above, since a dye is blended into the polarizer protective film, the hue shift can be suppressed by adjusting the type and amount of the dye, regardless of the wavelength dispersion characteristic.

The λ/4 plate is preferably a stretched film of a resin film containing a dye. The stretching direction of the stretched film is not limited and may be, for example, the longitudinal direction and/or the width direction or the oblique direction. Examples of the stretching method include transverse uniaxial stretching, fixed-end biaxial stretching, and sequential biaxial stretching. A specific example of fixed-end biaxial stretching is a method in which a resin film is stretched in the short direction (width direction) while running in the longitudinal direction. This method may appear as transverse uniaxial stretching. In addition, by employing oblique stretching, a long stretched film having an orientation axis (slow axis) at a predetermined angle with respect to the width direction can be obtained. Specific examples of oblique stretching methods are described in, for example, WO2012/053218, WO2016/047465, JP2013-97216A, etc. These descriptions are incorporated herein by reference.

When the longitudinal direction is taken as 0°, the λ/4 plate obtained by oblique stretching has an orientation axis (slow axis) in a direction preferably of 20° to 60°, more preferably of 35° to 55°, even more preferably of 38° to 52°, even more preferably of 40° to 50°, even more preferably of 42° to 48°, and particularly preferably of 44° to 46° clockwise, or preferably of 110° to 150°, more preferably of 128° to 142°, even more preferably of 130° to 140°, even more preferably of 132° to 138°, and particularly preferably of 134° to 136°.

When the polarizer protective film is a λ/2 plate, its in-plane retardation Re(550) is preferably 200 nm to 320 nm, more preferably 210 nm to 280 nm, and most preferably 230 nm to 240 nm. Typically, the λ/2 plate preferably has an index ellipsoid of nx>ny=nz. The Nz coefficient of the λ/2 plate is, for example, 0.9 to 2, preferably 1 to 1.5, and more preferably 1 to 1.3.

The thickness of the polarizer protective film that functions as a λ/2 plate can be set so that it can function most appropriately as a λ/2 plate. In other words, the thickness can be set so that a desired in-plane retardation is obtained. Specifically, the thickness is preferably 10 μm to 80 μm, more preferably 10 μm to 60 μm, and most preferably 30 μm to 50 μm.

The λ/2 plate may exhibit an inverse dispersion wavelength characteristic in which the phase difference value increases with the wavelength of the measurement light, a positive wavelength dispersion characteristic in which the phase difference value decreases with the wavelength of the measurement light, or a flat wavelength dispersion characteristic in which the phase difference value changes very little with the wavelength of the measurement light. As described above, since a dye is blended into the polarizer protective film, the hue shift can be suppressed by adjusting the type and amount of the dye, regardless of the wavelength dispersion characteristic.

The λ/2 plate is preferably a stretched film of a resin film containing the above-mentioned dye. The stretching method of the resin film can be the same as the stretching method exemplified when the polarizer protective film is a λ/4 plate.

The λ/2 plate obtained by oblique stretching has an orientation axis (slow axis) in a clockwise or counterclockwise direction, preferably at 10° to 20°, more preferably at 13° to 17°, and particularly preferably at about 15°, when the longitudinal direction is taken as 0°.

In another embodiment, the polarizer protective film is optically isotropic. In this specification, "optically isotropic" means that the in-plane retardation Re(550) is 0 nm to 10 nm, and the retardation in the thickness direction Rth(550) is -10 nm to +10 nm. In this embodiment, the thickness of the polarizer protective film is preferably 10 μm to 80 μm, more preferably 15 μm to 60 μm, and even more preferably 20 μm to 40 μm.

B. Polarizing Plate A polarizing plate according to an embodiment of the present invention has a polarizer and the polarizer protective film (hereinafter, colored polarizer protective film) described in Section A arranged on at least one side of the polarizer. The visible light transmittance of the polarizing plate is preferably 20% or more, more preferably 25% or more, and even more preferably 30% to 50%. The polarization degree of the polarizing plate is 99.9% or more, and preferably 99.95% or more.

The change rate of the visible light transmittance of the polarizing plate after 96 hours in an environment of 65° C. and 90% RH is typically 10% or less, preferably 5.0% or less, more preferably 3.0% or less, even more preferably 2.0% or less, and even more preferably 0% to 1.0%. By using a resin film containing a dye and having a low water absorption rate as a polarizer protective film, a polarizing plate having excellent durability in a humid environment can be obtained. The change rate of the visible light transmittance is calculated based on the following formula.
Change in visible light transmittance (%)=(visible light transmittance after 96 hours−initial visible light transmittance)/initial visible light transmittance×100

1 and 2 are each a schematic cross-sectional view of a polarizing plate according to one embodiment of the present invention. Polarizing plate 100a has a polarizer 10 and a colored polarizer protective film 20 arranged on one side thereof. Polarizing plate 100b has a polarizer 10, a colored polarizer protective film 20 arranged on one side thereof, and a second polarizer protective film 30 arranged on the other side thereof. The second polarizer protective film 30 may be a colored polarizer protective film or may be a normal polarizer protective film (a polarizer protective film that does not contain a dye).

Although not shown, the colored polarizer protective film 20 is typically laminated to the surface of the polarizer 10 via an adhesive layer. The second polarizer protective film 30 is laminated to the surface of the polarizer 10 via an adhesive layer or in close contact without an adhesive layer. Any suitable pressure-sensitive adhesive layer or adhesive layer may be used as the adhesive layer. The pressure-sensitive adhesive layer is typically formed of an acrylic pressure-sensitive adhesive. The adhesive layer is typically formed of an ultraviolet-curing adhesive or a polyvinyl alcohol adhesive.

Any suitable polarizer can be used as the polarizer 10. Examples include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films, which have been uniaxially stretched after adsorbing a dichroic substance such as iodine or a dichroic dye, and polyene-based oriented films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride. Among these, a polarizer in which a dichroic substance such as iodine is adsorbed on a polyvinyl alcohol film and then uniaxially stretched is particularly preferred, as it has a high polarization dichroic ratio. The thickness of the polarizer is preferably 0.5 μm to 80 μm.

A polarizer obtained by uniaxially stretching a polyvinyl alcohol-based film by adsorbing iodine is typically produced by dyeing the polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times its original length. Stretching may be performed after dyeing, or while dyeing, or dyeing may be performed after stretching. In addition to stretching and dyeing, the film may be produced by, for example, swelling, crosslinking, adjustment, washing with water, drying, and other treatments. For example, by immersing the polyvinyl alcohol-based film in water and washing it before dyeing, it is possible to clean the stains and blocking inhibitor on the surface of the polyvinyl alcohol-based film, and also to swell the polyvinyl alcohol-based film and prevent uneven dyeing. The polyvinyl alcohol-based film may be a single-layer film (a film formed from a normal film), or may be a polyvinyl alcohol-based resin layer formed by coating on a resin substrate. The technology for producing a polarizer from a single-layer polyvinyl alcohol-based film is well known in the art. A technique for producing a polarizer from a polyvinyl alcohol-based resin layer formed by coating on a resin substrate is described, for example, in JP 2009-098653 A.

The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The single transmittance of the polarizer is preferably between 38% and 45.5%, and more preferably between 40% and 45%.

The degree of polarization of the polarizer is preferably 99.9% or more, and more preferably 99.95% or more.

In the case of a polarizer protective film that does not contain a dye, the second polarizer protective film 30 is formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of materials that are the main components of the film include cellulose-based resins such as triacetyl cellulose (TAC), and transparent resins such as polyester, polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyethersulfone, polysulfone, polystyrene, polynorbornene, polyolefin, (meth)acrylic, and acetate. In addition, thermosetting resins or ultraviolet-curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone are also included. In addition, glassy polymers such as siloxane polymers are also included. Polymer films described in JP 2001-343529 A (WO01/37007) can also be used. The material for this film can be, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain, such as a resin composition having an alternating copolymer of isobutene and N-methylmaleimide, and an acrylonitrile-styrene copolymer. The polymer film can be, for example, an extrusion molded product of the above resin composition.

When the polarizing plate is applied to an image display device, if the second polarizer protective film is disposed on the opposite side to the optical cell (if it is an outer protective layer), the thickness of the second polarizer protective film is typically 300 μm or less, preferably 100 μm or less, more preferably 5 μm to 80 μm, and even more preferably 10 μm to 60 μm. Note that if a surface treatment is applied, the thickness of the outer protective layer includes the thickness of the surface treatment layer.

When the polarizing plate is applied to an image display device, if the second polarizer protective film is disposed on the optical cell side (if it is an inner protective layer), the thickness of the second polarizer protective film is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm, and even more preferably 10 μm to 60 μm.

As described above, the colored polarizer protective film 20 is the polarizer protective film described in section A. When the colored polarizer protective film is optically anisotropic and also functions as a retardation film, the polarizing plate 100a or 100b is a retardation layer-attached polarizing plate. By arranging such a retardation layer-attached polarizing plate on the viewing side of the optical cell so that the colored polarizer protective film (retardation layer) is closer to the optical cell than the polarizer, the viewing angle can be improved and color unevenness on the screen can be suppressed. This effect is particularly noticeable when the colored polarizer protective film is a wide obliquely stretched film (for example, an obliquely stretched film with a width of 600 mm or more, preferably 800 mm to 2000 mm). Specifically, the obliquely stretched film is usually laminated to the polarizer in a so-called roll-to-roll process to form a long polarizing plate, which is then cut to the desired dimensions and attached to the optical cell. Here, polarizing plates for large screens (for example, for screens of 40 inches or more, preferably 50 inches or more) made using wide obliquely stretched films tend to have large retardation unevenness in the plane, especially in the diagonal corners, and the retardation unevenness can cause color unevenness on the screen. In contrast, with the above polarizing plate, the color control independent of retardation is possible because the colored polarizer protective film contains a dye, so that color unevenness on the screen can be suppressed. In this specification, the "roll-to-roll process" refers to a method in which long films are continuously laminated together while being transported by rolls, with their longitudinal directions aligned.

When the colored polarizer protective film 20 functions as a λ/4 plate, the polarizing plate 100a or 100b can function as a circular polarizing plate by arranging the film so that the angle between the absorption axis of the polarizer 10 and the slow axis of the colored polarizer protective film 20 is, for example, 35° to 55°, preferably 38° to 52°, more preferably 40° to 50°, even more preferably 42° to 48°, and particularly preferably 44° to 46°, clockwise or counterclockwise.

The circular polarizing plate can also function as an anti-reflection film, for example, by arranging a colored polarizer protective film that functions as a λ/4 plate on the viewing side of the optical cell so that it is on the viewing side of the polarizer. Specifically, the circular polarizing plate exhibits excellent anti-reflection function by the colored polarizer protective film absorbing light of a specific wavelength. In addition, the colored polarizer protective film selectively absorbs light in a specific wavelength range, so that the reflection hue can be appropriately adjusted and a polarizing plate that can contribute to a wide color gamut of the image display device can be obtained. For example, by using a colored polarizer protective film having an absorption maximum wavelength in the wavelength bands ranging from 440 nm to 510 nm and 560 nm to 610 nm, mixing of red light and green light, and green light and blue light can be effectively prevented, and as a result, the color gamut of the image display device can be widened, and bright and vivid image quality can be obtained.

Figure 3 is a schematic cross-sectional view of a polarizing plate according to another embodiment of the present invention. Polarizing plate 100c has a second polarizer protective film 30, a polarizer 10, a colored polarizer protective film 20, and a retardation film 40, in this order. In this embodiment, the colored polarizer protective film 20 functions as a λ/2 plate. The retardation film 40 is a retardation film that functions as a λ/4 plate. In polarizing plate 100c, the angle between the absorption axis of polarizer 10 and the slow axis of retardation film 40 is preferably 65° to 85°, more preferably 72° to 78°, and even more preferably about 75°, clockwise or counterclockwise. Furthermore, the angle between the absorption axis of polarizer 10 and the slow axis of colored polarizer protective film 20 is preferably 10° to 20°, more preferably 13° to 17°, and even more preferably about 15°, clockwise or counterclockwise. By arranging the two retardation films at the axial angles described above, a circular polarizer with excellent circular polarization properties (and, as a result, excellent anti-reflection properties) over a wide bandwidth can be obtained.

C. Image display device The polarizing plate described in the above item B can be applied to an image display device equipped with an optical cell. Therefore, the present invention includes an image display device equipped with the above polarizing plate. Representative examples of image display devices include a liquid crystal display device equipped with a liquid crystal cell, an organic electroluminescence (EL) cell, and the like. Typically, the polarizing plate is disposed on the viewing side of an optical cell such as a liquid crystal cell or an organic EL cell, and can stably exhibit a viewing angle improvement effect and/or an anti-reflection effect over a wide band. In addition, by disposing the polarizing plate so that the colored polarizer protective film is closer to the optical cell than the polarizer, a color unevenness suppression effect can be obtained in addition to the viewing angle improvement effect. Note that the liquid crystal cell and the organic EL cell are not characteristic parts of the present invention, and configurations well known in the industry can be adopted, so detailed explanations are omitted.

The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples. The methods for measuring each characteristic are as follows.

(1) Front Retardation The film to be measured was cut into a length of 4 cm and a width of 4 cm to be used as a measurement sample. The in-plane retardation of the measurement sample was measured using Axometrics' product name "Axoscan". The measurement wavelength was 550 nm, and the measurement temperature was 23°C. (2) Visible Light Transmittance The visible light transmittance of the polarizing plates prepared in the examples and comparative examples was measured using a UV-visible spectrophotometer (manufactured by JASCO Corporation, product name "V7000 series"). Specifically, the transmittance Ts of the polarizing plate at wavelengths of 380 nm to 780 nm was measured using a UV-visible spectrophotometer (manufactured by JASCO Corporation V-7100), and the visible light transmittance Ts was determined. This Ts is the Y value measured using a 2-degree visual field (C light source) according to JIS Z8701 and subjected to luminosity correction.
(3) Water Absorption The colored layers (colored polarizer protective films or colored adhesive layers) used in the Examples and Comparative Examples were measured in accordance with the "Test method for water absorption and boiling water absorption of plastics" described in JIS K 7209. The size of the test piece was a square flat plate with sides of 50 mm, and the test piece was immersed in water at a temperature of 25°C for 24 hours, and the weight change before and after immersion was measured to determine the water absorption rate. The unit is %.
(4) Haze For the colored layers (colored polarizer protective films or colored adhesive layers) used in the examples and comparative examples, haze was measured using a haze meter (manufactured by Murakami Color Science Laboratory, product name "HN-150") according to the method defined in JIS 7136.
(5) Thickness Using a thickness tester, the thickness in the width direction was measured at intervals of 10 mm, and the average value was calculated as the thickness.

[Example 1]
1. Preparation of Polarizer A long roll of a polyvinyl alcohol (PVA)-based resin film (manufactured by Kuraray, product name "PE3000") having a thickness of 30 μm was uniaxially stretched in the longitudinal direction to 5.9 times its original size using a roll stretching machine, while simultaneously undergoing swelling, dyeing, crosslinking, and washing treatments, and finally a drying treatment, to prepare a polarizer having a thickness of 12 μm.
Specifically, the film was stretched 2.2 times while being treated with pure water at 20°C for the swelling treatment. Next, the film was stretched 1.4 times while being treated in an aqueous solution at 30°C in which the weight ratio of iodine to potassium iodide was 1:7, and the iodine concentration was adjusted so that the single transmittance of the resulting polarizer was 45.0%. Furthermore, a two-stage crosslinking treatment was adopted for the crosslinking treatment, and the film was stretched 1.2 times while being treated in an aqueous solution at 40°C in which boric acid and potassium iodide were dissolved. The aqueous solution at the first crosslinking treatment had a boric acid content of 5.0% by weight and a potassium iodide content of 3.0% by weight. The film was stretched 1.6 times while being treated in an aqueous solution at 65°C in which boric acid and potassium iodide were dissolved. The aqueous solution at the second crosslinking treatment had a boric acid content of 4.3% by weight and a potassium iodide content of 5.0% by weight. The cleaning treatment was performed with an aqueous potassium iodide solution at 20° C. The aqueous solution used for the cleaning treatment had a potassium iodide content of 2.6% by weight. Finally, the film was dried at 70° C. for 5 minutes to obtain a polarizer.

2. Preparation of colored polarizer protective film 81.98 parts by mass of isosorbide (hereinafter sometimes abbreviated as "ISB"), 47.19 parts by mass of tricyclodecane dimethanol (hereinafter sometimes abbreviated as "TCDDM"), 175.1 parts by mass of diphenyl carbonate (hereinafter sometimes abbreviated as "DPC"), and 0.979 parts by mass of 0.2% by mass aqueous solution of cesium carbonate as a catalyst were charged into a reaction vessel, and in a nitrogen atmosphere, as the first step of the reaction, the heating tank temperature was heated to 150 ° C., and the raw materials were dissolved while stirring as necessary (about 15 minutes). Next, the pressure was changed from normal pressure to 13.3 kPa, and the heating tank temperature was increased to 190 ° C. over 1 hour, while the generated phenol was extracted from the reaction vessel. After the entire reaction vessel was kept at 190°C for 15 minutes, in the second step, the pressure inside the reaction vessel was set to 6.67 kPa, the heating tank temperature was raised to 230°C in 15 minutes, and the generated phenol was extracted outside the reaction vessel. As the stirring torque of the stirrer increased, the temperature was raised to 250°C in 8 minutes, and the pressure inside the reaction vessel was allowed to reach 0.200 kPa or less in order to remove the further generated phenol. After the predetermined stirring torque was reached, the reaction was terminated, and the reaction product produced was extruded into water to obtain polycarbonate resin pellets. The obtained polycarbonate resin was vacuum dried at 80°C for 5 hours, and then 0.29 parts by weight of a dye (manufactured by Yamada Chemical Co., Ltd., product name FDG-007) was added to 100 parts by weight of the resin at the same time, and a colored polycarbonate resin film having a thickness of 70 μm was produced using a film forming device equipped with a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., cylinder setting temperature: 250°C), a T-die (width 300 mm, setting temperature: 250°C), a chill roll (setting temperature: 120 to 130°C) and a winder.
Furthermore, the unstretched polycarbonate resin film was subjected to a preheating treatment and simultaneous biaxial stretching using a simultaneous biaxial stretching machine to obtain a colored polarizer protective film that functions as a retardation film. The preheating temperature was 145° C. The stretching temperature was 140° C. (Tg+10° C.), and the stretching ratio in the longitudinal direction was 1.2 times and the stretching ratio in the transverse direction was 1.9 times.
The obtained colored polarizer protective film had a thickness of 30 μm, a front retardation Re(550) of 144 nm, and an absorption maximum wavelength of 590 nm. The slow axis direction was 135° with respect to the longitudinal direction.

3. Preparation of Polarizing Plate A TAC film (manufactured by Fujifilm Corporation, product name "TG60UL", thickness: 60 μm) was bonded to one side of the polarizer via a UV-curable adhesive by roll-to-roll, and then the colored polarizer protective film was bonded to the other side of the polarizer via a UV-curable adhesive by roll-to-roll, thereby obtaining a long polarizing plate 1 having a configuration of protective film/polarizer/colored polarizer protective film.

An acrylic adhesive layer was provided on the colored polarizer protective film side surface of polarizing plate 1, and laminate 1 was obtained by bonding the plate to an organic EL panel of 55 inches or more via the acrylic adhesive layer.

[Example 2]
A colored polarizer protective film was obtained in the same manner as in Example 1, except that 0.3 parts by weight of "PD-320" manufactured by Yamamoto Chemical Industries, Ltd. was used as the dye and the stretching temperature was 139°C (Tg+9°C). The obtained colored polarizer protective film had a thickness of 30 μm, a front retardation Re(550) of 135 nm, and an absorption maximum wavelength of 590 nm. In addition, the slow axis direction was 135° with respect to the longitudinal direction.
A long polarizing plate 2 having a structure of protective film/polarizer/colored polarizer protective film was obtained in the same manner as in Example 1, except that the above-mentioned colored polarizer protective film was used.

An acrylic adhesive layer was provided on the colored polarizer protective film side surface of polarizing plate 2, and laminate 2 was obtained by bonding it to one side of an organic EL panel of 55 inches or more via the acrylic adhesive layer.

[Example 3]
A colored polarizer protective film was obtained in the same manner as in Example 1, except that the amount of the dye added was 0.18 parts by weight and the stretching temperature was 142° C. (Tg+12° C.). The thickness of the obtained colored polarizer protective film was 20 μm, the front retardation Re(550) was 100 nm, and the absorption maximum wavelength was 590 nm. In addition, the slow axis direction was 135° with respect to the longitudinal direction.
A long polarizing plate 3 having a structure of protective film/polarizer/colored polarizer protective film was obtained in the same manner as in Example 1, except that the above-mentioned colored polarizer protective film was used.

An acrylic adhesive layer was applied to the protective film (TAC film) side surface of the polarizing plate 3, and the polarizing plate 3 was attached to one side of an organic EL panel of 55 inches or more via the acrylic adhesive layer to obtain the laminate 3.

[Example 4]
A colored polarizer protective film was obtained in the same manner as in Example 1, except that a norbornene-based polymer (trade name ARTON, manufactured by JSR Corporation) was used, the amount of dye added was 0.2 parts by weight, and the stretching temperature was Tg+12 degrees. The thickness of the obtained colored polarizer protective film was 25 μm, the front retardation Re(550) was 100 nm, and the absorption maximum wavelength was 590 nm. In addition, the slow axis direction was 135° with respect to the longitudinal direction.
A long polarizing plate 4 having a structure of protective film/polarizer/colored polarizer protective film was obtained in the same manner as in Example 1, except that the above-mentioned colored polarizer protective film was used.

An acrylic adhesive layer was provided on the protective film (TAC film) side surface of polarizing plate 4, and the polarizing plate was attached to one side of an organic EL panel of 55 inches or more via the acrylic adhesive layer to obtain laminate 4.

[Example 5]
A colored polarizer protective film was obtained in the same manner as in Example 4, except that the amount of the dye added was 0.37 parts by weight and the stretching temperature was Tg+10° C. The thickness of the obtained colored polarizer protective film was 40 μm, the front retardation Re(550) was 140 nm, and the absorption maximum wavelength was 590 nm. In addition, the slow axis direction was 135° with respect to the longitudinal direction.
A long polarizing plate 5 having a structure of protective film/polarizer/colored polarizer protective film was obtained in the same manner as in Example 1, except that the above-mentioned colored polarizer protective film was used.

An acrylic adhesive layer was provided on the colored polarizer protective film side surface of polarizing plate 5, and laminate 5 was obtained by bonding it to one side of an organic EL panel of 55 inches or more via the acrylic adhesive layer.

[Example 6]
A colored polarizer protective film was obtained in the same manner as in Example 1, except that the amount of the dye added was 0.36 parts by weight and the stretching temperature was Tg+5 degrees. The thickness of the obtained colored polarizer protective film was 40 μm, the front retardation Re(550) was 270 nm, and the absorption maximum wavelength was 590 nm. In addition, the slow axis direction was 135° with respect to the longitudinal direction.
A long polarizing plate 6 having a structure of protective film/polarizer/colored polarizer protective film was obtained in the same manner as in Example 1, except that the above-mentioned colored polarizer protective film was used.

An acrylic adhesive layer was provided on the protective film (TAC film) side surface of the polarizing plate 6, and the polarizing plate 6 was attached to one side of an organic EL panel of 55 inches or more via the acrylic adhesive layer to obtain a laminate 6.

[Example 7]
A colored polarizer protective film was obtained in the same manner as in Example 1, except that an acrylic resin (manufactured by Kaneka Corporation, product name HTX) was used, and 0.39 parts by weight of a dye manufactured by Yamamoto Chemical Industries, Ltd., product name "PD-320" was used. The obtained colored polarizer protective film had a thickness of 40 μm, a front retardation Re(550) of 0 nm, and an absorption maximum wavelength at 590 nm.
A long polarizing plate 7 having a structure of protective film/polarizer/colored polarizer protective film was obtained in the same manner as in Example 1, except that the above-mentioned colored polarizer protective film was used.

An acrylic adhesive layer was provided on the protective film (TAC film) side surface of polarizing plate 7, and laminate 7 was obtained by attaching it to one side of an organic EL panel of 55 inches or more via the acrylic adhesive layer.

[Example 8]
A colored polarizer protective film was obtained in the same manner as in Example 1, except that a PET resin was used and 0.18 parts by weight of a dye manufactured by Yamamoto Chemical Industries, Ltd., product name "PD-320" was used. The obtained colored polarizer protective film had a thickness of 20 μm, a front retardation Re(550) of 350 nm, and an absorption maximum wavelength at 590 nm.
A long polarizing plate 8 having a structure of protective film/polarizer/colored polarizer protective film was obtained in the same manner as in Example 1, except that the above-mentioned colored polarizer protective film was used.

An acrylic adhesive layer was applied to the protective film (TAC film) side surface of the polarizing plate 8, and the polarizing plate was attached to one side of an organic EL panel of 55 inches or more via the acrylic adhesive layer to obtain the laminate 8.

[Comparative Example 1]
1. Preparation of Polarizer A polarizer was prepared in the same manner as in Example 1.
2. Preparation of Retardation Film A retardation film was obtained in the same manner as in the preparation of the colored polarizer protective film of Example 1, except that no dye was added. The thickness of the obtained retardation film was 30 μm, and the front retardation Re (550) was 144 nm. The slow axis direction was 135° with respect to the longitudinal direction.
3. Preparation of colored adhesive layer A colored adhesive was prepared by mixing 100 parts by weight of an acrylic polymer obtained by copolymerizing n-butyl acrylate and a hydroxyl group-containing monomer with 0.3 parts by weight of a radical generator (benzoyl peroxide, manufactured by Nippon Oil & Fats Co., Ltd., trade name "Niper BMT"), 1 part by weight of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, trade name "Coronate L"), 0.3 parts by weight of a dye (manufactured by Yamada Chemical Co., Ltd., trade name "FDG-007"), and 0.2 parts by weight of a phenol-based antioxidant (manufactured by BASF Japan, trade name "IRGANOX1010"). The above adhesive was applied to a thickness of 20 μm on a PET substrate (manufactured by Mitsubishi Plastics, trade name "MRF38CK") that had been treated to facilitate the peeling of the adhesive, and dried at 155 ° C. for 2 minutes to obtain a colored adhesive layer. The resulting colored adhesive layer had a thickness of 23 μm and had a maximum absorption wavelength at 590 nm.
4. Preparation of Polarizing Plate A TAC film (manufactured by Fujifilm Corporation, product name "TG60UL", thickness: 60 μm) was attached to one side of the polarizer via a UV-curable adhesive by roll-to-roll, and then the retardation film was attached to the other side of the polarizer via a UV-curable adhesive by roll-to-roll, thereby obtaining a long polarizing plate C1 having a configuration of protective film/polarizer/retardation film (also serving as protective film).

The polarizing plate C1 was attached to one side of an organic EL panel of 55 inches or more via the colored adhesive layer to obtain a laminate C1. At this time, the polarizing plate C1 was laminated so that the retardation film side faces the organic EL panel.

[Comparative Example 2]
1. Preparation of Polarizer A polarizer was prepared in the same manner as in Example 1.
2. Preparation of Retardation Film A retardation film was obtained in the same manner as in the preparation of the colored polarizer protective film of Example 4, except that no dye was added. The thickness of the obtained retardation film was 25 μm, and the front retardation Re (550) was 100 nm. The slow axis direction was 135° with respect to the longitudinal direction.
3. Preparation of Colored Adhesive Layer A colored adhesive layer was obtained in the same manner as in Comparative Example 1, except that the amount of the dye added was 0.29 parts by weight. The obtained colored adhesive layer had a thickness of 23 μm and a maximum absorption wavelength at 590 nm.
4. Preparation of Polarizing Plate A TAC film (manufactured by Fujifilm Corporation, product name "TG60UL", thickness: 60 μm) was attached to one side of the polarizer via a UV-curable adhesive by roll-to-roll, and then the retardation film was attached to the other side of the polarizer via a UV-curable adhesive by roll-to-roll, thereby obtaining a long polarizing plate C2 having a configuration of protective film/polarizer/retardation film (also serving as protective film).

The polarizing plate C2 was attached to one side of an organic EL panel of 55 inches or more via the colored adhesive layer to obtain laminate C2. At this time, the protective film (TAC film) side of polarizing plate C2 was laminated so as to face the organic EL panel.

[Comparative Example 3]
1. Preparation of Polarizer A polarizer was prepared in the same manner as in Example 1.
2. Preparation of Retardation Film A retardation film was obtained in the same manner as in the preparation of the colored polarizer protective film of Example 5, except that no dye was added. The thickness of the obtained retardation film was 40 μm, and the front retardation Re (550) was 140 nm. In addition, the slow axis direction was 135° with respect to the longitudinal direction.
3. Preparation of Colored Adhesive Layer A colored adhesive layer was obtained in the same manner as in Comparative Example 1, except that 0.33 parts by weight of a dye manufactured by Yamamoto Chemical Industry Co., Ltd. under the trade name "PD-320" was added. The thickness of the obtained colored adhesive layer was 23 μm, and it had an absorption maximum wavelength at 590 nm.
4. Preparation of Polarizing Plate A TAC film (manufactured by Fujifilm Corporation, product name "TG60UL", thickness: 60 μm) was attached to one side of the polarizer via a UV-curable adhesive by roll-to-roll, and then the retardation film was attached to the other side of the polarizer via a UV-curable adhesive by roll-to-roll, thereby obtaining a long polarizing plate C3 having a configuration of protective film/polarizer/retardation film (also serving as protective film).

The polarizing plate C3 was attached to an organic EL panel of 55 inches or more via the colored adhesive layer to obtain laminate C3. At this time, the polarizing plate C3 was laminated so that the retardation film side faced the organic EL panel.

[Reference Example 1]
1. Preparation of Polarizer A polarizer was prepared in the same manner as in Example 1.
2. Preparation of Retardation Film A retardation film was obtained in the same manner as in the preparation of the colored polarizer protective film of Example 2, except that no dye was added. The thickness of the obtained retardation film was 30 μm, and the front retardation Re (550) was 135 nm. The slow axis direction was 135° with respect to the longitudinal direction.
3. Preparation of Polarizing Plate A TAC film (manufactured by Fujifilm Corporation, product name "TG60UL", thickness: 60 μm) was attached to one side of the polarizer via a UV-curable adhesive by roll-to-roll, and then the retardation film was attached to the other side of the polarizer via a UV-curable adhesive by roll-to-roll, thereby obtaining a long polarizing plate R1 having a configuration of protective film/polarizer/retardation film (also serving as protective film).

The polarizing plate R1 was attached to one side of an organic EL panel of 55 inches or more via an acrylic adhesive layer to obtain a laminate R1. At this time, the polarizing plate R1 was laminated so that the retardation film side faces the organic EL panel.

<Reliability Test>
The polarizing plates obtained in the examples and comparative examples were placed in an oven at 65° C. and 90% RH, and after 96 hours, they were taken out and the visible light transmittance was measured to determine the rate of change from the initial visible light transmittance (before being placed in the oven).

<Color unevenness evaluation>
The laminates obtained in the examples and comparative examples were visually inspected for in-plane unevenness in the off and on states. A level that was not problematic for practical use was rated as "good," and a level that was visible as an in-plane change in hue was rated as "poor."

As shown in Table 1, the polarizing plate using the colored polarizer protective film of the embodiment has a small rate of change in transmittance in a humid environment and is highly stable. It is also found that color unevenness is suppressed by placing the colored polarizer protective film of the embodiment on the optical cell side of the polarizer.

The polarizer protective film of the present invention can be suitably used in the manufacture of polarizing plates, circular polarizing plates, etc.

10 Polarizer 20 Colored polarizer protective film 30 Second polarizer protective film 100 Polarizing plate

Claims (9)

A polarizer and a polarizer protective film disposed on at least one side of the polarizer,
the polarizer protective film is a resin film containing a dye,
The water absorption rate of the polarizer protective film is 0% to 1.5% ,
the polarizer protective film has reverse dispersion wavelength characteristics and a front retardation Re(550) of 90 nm to 160 nm, and is arranged so that the angle between the slow axis and the absorption axis direction of the polarizer is 35° to 55° in a clockwise or counterclockwise direction, or has a front retardation Re(550) of 200 nm to 320 nm, and is arranged so that the angle between the slow axis and the absorption axis direction of the polarizer is 10° to 20° in a clockwise or counterclockwise direction,
the polarizer protective film has an absorption maximum wavelength in a wavelength band ranging from 440 nm to 510 nm and/or from 560 nm to 610 nm,
The change in visible light transmittance after 96 hours in an environment of 65° C. and 90% RH is 10% or less;
The polarizing plate is used in an organic EL display device including an organic EL cell , with the polarizer protective film being disposed on the organic EL cell side relative to the polarizer . The polarizing plate according to claim 1, wherein the polarizer protective film contains at least one resin selected from the group consisting of polyethylene terephthalate-based resins, acrylic-based resins, polycarbonate-based resins, and cycloolefin-based resins. The polarizing plate according to claim 1 or 2, wherein the polarizer protective film is a stretched resin film. The polarizing plate according to any one of claims 1 to 3, wherein the haze of the polarizer protective film is 3% or less. The polarizing plate according to any one of claims 1 to 4, wherein the polarizer and the polarizer protective film are bonded together via an ultraviolet-curable adhesive. The polarizing plate according to any one of claims 1 to 5, having a visible light transmittance of 20% or more. The polarizer is long,
the polarizer protective film is a long obliquely stretched film,
7. The polarizing plate according to claim 1, wherein the polarizer and the polarizer protective film are attached to each other with their longitudinal directions aligned. An organic EL display device comprising an organic EL cell and a polarizing plate according to any one of claims 1 to 6, which is disposed on the viewing side of the organic EL cell. The organic EL display device according to claim 8 , wherein the polarizer protective film of the polarizing plate is disposed closer to the organic EL cell than the polarizer.