Polarizing plate with phase difference layer and organic electroluminescent display device using the same

Abstract

To provide a polarizing plate with a phase difference layer in which discoloration is significantly suppressed when applied to an organic EL display device. [Solution] The polarizing plate with a phase difference layer of the present invention comprises a polarizing plate including a polarizer and a protective layer at least on the viewing side of the polarizer, and a phase difference layer disposed on the opposite side of the viewing side of the polarizing plate. The moisture permeability of the protective layer on the viewing side is 200 g / m 2 • It is 24 hours or longer, and is greater than the moisture permeability of the phase difference layer.

Description

[Technical Field]

[0001] The present invention relates to a polarizing plate with a phase difference layer and an organic electroluminescent (EL) display device using the same. [Background technology]

[0002] In recent years, with the spread of thin-screen displays, displays equipped with organic EL panels (organic EL display devices) have been proposed. Because organic EL panels have a highly reflective metal layer, they are prone to problems such as reflection of ambient light and reflection of the background. It is known that these problems can be prevented by providing a circular polarizer on the viewing side (for example, Patent Documents 1-3). However, circular polarizers provided in organic EL display devices have the problem of being prone to discoloration. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2003-311239 [Patent Document 2] Japanese Patent Publication No. 2002-372622 [Patent Document 3] Patent No. 3325560 [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention was made to solve the above-mentioned conventional problems, and its main objective is to provide a polarizing plate with a phase difference layer in which discoloration is significantly suppressed when applied to an organic EL display device. [Means for solving the problem]

[0005] The polarizing plate with a phase difference layer of the present invention comprises a polarizer and a protective layer on at least the viewing side of the polarizer, and a phase difference layer disposed on the opposite side of the viewing side of the polarizer. The moisture permeability of the protective layer on the viewing side is 200 g / m². 2• It is 24 hours or longer, and is greater than the moisture permeability of the phase difference layer. In one embodiment, the polarizing plate includes a protective layer only on the viewing side. In one embodiment, the difference between the moisture permeability of the visible protective layer and the moisture permeability of the phase difference layer is 200 g / m². 2 • It is 24 hours or longer. In one embodiment, the polarizing plate further includes another protective layer on the side opposite to the viewing side of the polarizer, and the water permeability of the viewing-side protective layer is greater than the smaller of the water permeability of the other protective layer and the water permeability of the phase difference layer. In one embodiment, the phase difference layer is an orientation solidification layer of a liquid crystal compound, and the water permeability of the viewing-side protective layer is greater than the water permeability of the other protective layer. In one embodiment, the difference between the water permeability of the viewing-side protective layer and the smaller of the water permeability of the other protective layer and the water permeability of the phase difference layer is 200 g / m 2 • It is 24 hours or longer. In one embodiment, the moisture permeability of the other protective layer is 150 g / m². 2 • Less than 24 hours In one embodiment, the thickness of the polarizer is 8 μm or less. In one embodiment, the total thickness of the polarizing plate with the phase difference layer is 20 μm or more and 100 μm or less. According to another aspect of the present invention, an organic electroluminescent display device is provided. This organic electroluminescent display device comprises the polarizing plate with the phase difference layer described above. [Effects of the Invention]

[0006] According to embodiments of the present invention, in a polarizing plate with a phase difference layer, by making the moisture permeability of the viewing-side protective layer greater than the smaller of the moisture permeability of the protective layer on the opposite side of the viewing side (if present) and the moisture permeability of the phase difference layer, it is possible to realize a polarizing plate with a phase difference layer in which discoloration is significantly suppressed when applied to an organic EL display device. [Brief explanation of the drawing]

[0007] [Figure 1]Schematic cross-sectional view of a polarizing plate with a phase difference layer according to one embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0009] (Definition of Terms and Symbols) The definitions of terms and symbols in this specification are as follows. (1) Refractive Index (nx, ny, nz) "nx" is the refractive index in the direction where the in-plane refractive index is maximum (i.e., the slow axis direction), "ny" is the refractive index in the direction orthogonal 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 phase difference measured with light of wavelength λ nm at 23°C. For example, "Re(550)" is the in-plane phase difference measured with light of wavelength 550 nm at 23°C. Re(λ) is obtained by the formula: Re(λ) = (nx - ny) × d when the thickness of the layer (film) is d (nm). (3) Phase Difference in the Thickness Direction (Rth) "Rth(λ)" is the phase difference in the thickness direction measured with light of wavelength λ nm at 23°C. For example, "Rth(550)" is the phase difference in the thickness direction measured with light of wavelength 550 nm at 23°C. Rth(λ) is obtained by the formula: Rth(λ) = (nx - nz) × d when the thickness of the layer (film) is d (nm). (4) Nz Coefficient The Nz coefficient is obtained by Nz = Rth / Re. (5) Angle When referring to an angle in this specification, the angle includes both clockwise and counterclockwise with respect to the reference direction. Therefore, for example, "45°" means ±45°.

[0010] A. Overall Configuration of the Polarizing Plate with a Phase Difference Layer Figure 1 is a schematic cross-sectional view of a polarizing plate with a phase difference layer according to one embodiment of the present invention. The polarizing plate with a phase difference layer 100 in the illustrated example typically has a polarizing plate 10 and a phase difference layer 20 in this order from the viewing side. The polarizing plate 10 includes a polarizer 11 and a protective layer (viewing side protective layer) 12 at least on the viewing side of the polarizer 11. In the illustrated example, a protective layer (inner protective layer) 13 is provided on the side of the polarizer 11 opposite to the viewing side, but the protective layer 13 may be omitted depending on the purpose, etc. For example, if the phase difference layer 20 is made of a stretched resin film and can also serve as a protective layer for the polarizer, the protective layer 13 may be omitted. On the other hand, if the phase difference layer 20 is an orientation solidified layer of a liquid crystal compound, the protective layer 13 is typically provided. In practical terms, an adhesive layer (not shown) is provided on the side of the phase difference layer 20 opposite to the polarizing plate 10 (i.e., as the outermost layer opposite to the viewing side), so that the polarizing plate with the phase difference layer can be attached to an organic EL cell. Furthermore, it is preferable that a release film is temporarily attached to the surface of the adhesive layer until the polarizing plate with the phase difference layer is put into use. By temporarily attaching the release film, the adhesive layer is protected and roll formation of the polarizing plate with the phase difference layer becomes possible.

[0011] In embodiments of the present invention, the moisture permeability of the protective layer 12 is greater than the smaller of the moisture permeability of the protective layer 13 (if present) and the moisture permeability of the phase difference layer 20. Specifically, this is as follows: (1) If the protective layer 13 is omitted, the moisture permeability of the protective layer 12 is greater than the moisture permeability of the phase difference layer 20; (2) If the protective layer 13 is present, the moisture permeability of the protective layer 12 is greater than the smaller of the moisture permeability of the protective layer 13 and the moisture permeability of the phase difference layer 20; (3) If the protective layer 13 is present and the phase difference layer 20 is an orientation solidification layer of a liquid crystal compound, the moisture permeability of the protective layer 12 is greater than the moisture permeability of the protective layer 13. The inventors faced a new problem when applying a polarizing plate with a phase difference layer to an organic EL display device: the polarizing plate with a phase difference layer became discolored. After diligently investigating this problem, they discovered that the cause of the discoloration was ammonia (substantially ammonium ions) generated from the organic EL panel. Furthermore, after diligently studying means to suppress decolorization by ammonia, we discovered that decolorization can be significantly suppressed by blocking ammonium ions from entering the polarizer as much as possible and expelling as many ammonium ions that have entered as possible. Based on this finding, we solved the new problem by reducing the moisture permeability of the protective layer or phase difference layer on the side opposite to the viewing side (organic EL panel side) to block ammonium ions from entering the polarizer as much as possible, and by increasing the moisture permeability on the viewing side (the side farther from the organic EL panel) to expel as many ammonium ions that have entered as possible. It should be noted that the protective layer of a polarizer is designed to have low moisture permeability on the outer (viewing side) protective layer, as its main purpose is to protect the polarizer from moisture (water vapor). However, the embodiment of the present invention is based on a technical idea that is completely opposite to this common technical practice in the industry.

[0012] The difference between the moisture permeability of protective layer 12, the moisture permeability of protective layer 13 (if present), and the moisture permeability of phase difference layer 20 (whichever is smaller) is preferably 200 g / m². 2 • 24 hours or more, more preferably 220 g / m² 2 • 24 hours or more, more preferably 250 g / m² 2·More than 24 hours, particularly preferably 300 g / m 2 ·More than 24 hours. The upper limit of the difference is, for example, 600 g / m 2 ·It can be 24 hours. If the difference is within such a range, the discoloration of the retardation film with a phase difference layer can be further better suppressed.

[0013] The moisture permeability of the protective layer 12 is 200 g / m 2 ·More than 24 hours, preferably 300 g / m 2 ·More than 24 hours, more preferably 330 g / m 2 ·More than 24 hours, still more preferably 360 g / m 2 ·More than 24 hours, particularly preferably 400 g / m 2 ·More than 24 hours. The upper limit of the moisture permeability of the protective layer 12 is, for example, 650 g / m 2 ·It can be 24 hours. The moisture permeability of the protective layer 13 is preferably 150 g / m 2 ·24 hours or less, more preferably 100 g / m 2 ·24 hours or less, still more preferably 70 g / m 2 ·24 hours or less, particularly preferably 50 g / m 2 ·24 hours or less. The lower the moisture permeability of the protective layer 13, the better, and the lower limit is, for example, 5 g / m 2 ·It can be 24 hours. When the protective layer 13 does not exist, or when the moisture permeability of the retardation layer 20 is smaller than that of the protective layer 13, the moisture permeability of the retardation layer 20 is preferably 150 g / m 2 ·24 hours or less, more preferably 100 g / m 2 ·24 hours or less, still more preferably 70 g / m 2 ·24 hours or less, particularly preferably 50 g / m 2 ·24 hours or less. The lower the moisture permeability of the retardation layer 20, the better, and the lower limit is, for example, 5 g / m 2 ·It can be 24 hours. If the moisture permeabilities of the protective layers 12 and 13 and the retardation layer 20 are within such a range, it is easy to make the difference in the above-mentioned moisture permeabilities within a desired range. The moisture permeability can be measured in accordance with JIS Z 0208.

[0014] The total thickness of the polarizing plate with a phase difference layer is preferably 120 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less. The lower limit of the total thickness is preferably 20 μm, and more preferably 45 μm. A polarizing plate with a phase difference layer having such a total thickness can have extremely excellent flexibility and bending durability. As a result, the polarizing plate with a phase difference layer can be particularly suitably applied to curved organic EL display devices and / or bendable or foldable organic EL display devices.

[0015] A polarizing plate with a phase difference layer may further include other optical functional layers. The type, characteristics, number, combination, and placement position of the optical functional layers that can be provided on the polarizing plate with a phase difference layer can be appropriately set according to the purpose. For example, a polarizing plate with a phase difference layer may further include a conductive layer or an isotropic substrate with a conductive layer (neither of which are shown). Typically, the conductive layer or the isotropic substrate with a conductive layer is provided on the outside of the phase difference layer 20 (opposite side from the polarizing plate 10). When a conductive layer or an isotropic substrate with a conductive layer is provided, the polarizing plate with a phase difference layer can be applied to a so-called inner touch panel type input display device in which a touch sensor is incorporated between the organic EL cell and the polarizing plate. Also, for example, a polarizing plate with a phase difference layer may further include other phase difference layers. The optical characteristics (e.g., refractive index characteristics, in-plane phase difference, Nz coefficient, photoelastic coefficient), thickness, placement position, etc. of the other phase difference layers can be appropriately set according to the purpose.

[0016] The polarizing plate with a phase difference layer may be in the form of a single sheet or a long sheet. In this specification, "long sheet" means an elongated shape in which the length is sufficiently long relative to the width, and for example, includes an elongated shape in which the length is 10 times or more, preferably 20 times or more, relative to the width. The long polarizing plate with a phase difference layer can be wound into a roll.

[0017] The components of a polarizing plate with a phase difference layer will be explained in more detail below.

[0018] B. Polarizing plate B-1.Polarizer Any suitable polarizer can be used as the polarizer 11. For example, the resin film forming the polarizer may be a single layer resin film or a laminate of two or more layers.

[0019] Specific examples of polarizers composed of a single layer of resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films, which have been subjected to dyeing and stretching treatments with dichroic substances such as iodine or dichroic dyes, as well as polyene-based oriented films such as dehydrated PVA or dehydrochlorinated polyvinyl chloride. Preferably, polarizers obtained by dyeing a PVA film with iodine and uniaxially stretching are used because they have excellent optical properties.

[0020] The above-mentioned iodine dyeing is carried out, for example, by immersing the PVA film in an iodine aqueous solution. The stretching ratio for the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment, or during the dyeing process. Alternatively, dyeing may be performed after stretching. If necessary, the PVA film may be subjected to swelling, crosslinking, washing, drying, etc. For example, immersing the PVA film in water and washing it before dyeing can not only clean dirt and anti-blocking agents from the surface of the PVA film, but also swell the PVA film to prevent uneven dyeing.

[0021] Specific examples of polarizers obtained using a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer coated on the resin substrate can be produced, for example, by applying a PVA-based resin solution to a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, and obtaining a laminate of the resin substrate and the PVA-based resin layer; or by stretching and dyeing the laminate to make the PVA-based resin layer a polarizer. In this embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may, if necessary, further include air-stretching the laminate at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. The resulting resin substrate / polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate / polarizer laminate, and any appropriate protective layer may be laminated onto the peeled surface according to the purpose. Details of such polarizer manufacturing methods 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.

[0022] The thickness of the polarizer is preferably 15 μm or less, more preferably 12 μm or less, even more preferably 10 μm or less, and particularly preferably 8 μm or less. On the other hand, the thickness of the polarizer is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more. When the thickness of the polarizer is within this range, curling during heating can be well suppressed, and good durability of the appearance during heating can be obtained.

[0023] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, and preferably 44.5% to 46.0%. The degree of polarization of the polarizer is preferably 97.0% or higher, more preferably 99.0% or higher, and even more preferably 99.9% or higher.

[0024] B-2.Protective layer The viewing-side protective layer 12 and the inner protective layer 13 (if present) are each composed of any suitable film that can be used as a protective layer for the polarizer, provided that it has the moisture permeability described above. Typical materials for the inner protective layer 13 include cycloolefin resins such as polynorbornene, (meth)acrylic resins, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene, and polycarbonate resins. Typical examples of (meth)acrylic resins include (meth)acrylic resins having a lactone ring structure. (Meth)acrylic resins having a lactone ring structure are described, for example, in Japanese Patent Publication No. 2000-230016, Japanese Patent Publication No. 2001-151814, Japanese Patent Publication No. 2002-120326, Japanese Patent Publication No. 2002-254544, and Japanese Patent Publication No. 2005-146084. These publications are incorporated herein by reference. The inner protective layer 13 is preferably composed of a cycloolefin resin. Typical materials for the visible side protective layer 12 include cellulose resins such as triacetylcellulose (TAC) and resins that can form microporous films (e.g., polyurethane resins).

[0025] As described later, the polarizing plate with a phase difference layer is typically placed on the viewing side of the organic EL display device, and the protective layer 12 is also placed on that viewing side. Therefore, the protective layer 12 may be subjected to surface treatments such as hard coating, anti-reflective coating, anti-sticking coating, and anti-glare coating as needed. Furthermore / or, the protective layer 12 may be subjected to treatments that improve visibility when viewed through polarized sunglasses (typically, by providing (elliptic) circular polarization function or providing ultra-high phase difference) as needed. By applying such treatments, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, the polarizing plate with a phase difference layer can be suitably applied to organic EL display devices that can be used outdoors.

[0026] The thickness of the protective layer 12 can be appropriately set according to the desired moisture permeability. The thickness of the protective layer 12 is preferably 10 μm to 80 μm, more preferably 15 μm to 70 μm, and even more preferably 20 μm to 50 μm. If a surface treatment is applied, the thickness of the protective layer 12 includes the thickness of the surface treatment layer.

[0027] In one embodiment, the protective layer 13 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. The thickness of the protective layer 13 can also be appropriately set according to the desired moisture permeability. The thickness of the protective layer 13 is preferably 10 μm to 80 μm, more preferably 20 μm to 70 μm, and even more preferably 30 μm to 50 μm. If the phase difference layer 20 is a stretched resin film, the protective layer 13 can preferably be omitted from the viewpoint of thinning.

[0028] C. Retardation layer The phase difference layer 20 may be a single layer, or it may have a laminated structure (essentially a two-layer structure).

[0029] When the retardation layer 20 is a single layer, the retardation layer 20 can typically function as a λ / 4 plate. The retardation layer is typically provided to impart antireflection characteristics to an organic EL display device. The retardation layer typically exhibits a refractive index characteristic of nx > ny = nz. The in-plane retardation Re(550) of the retardation layer is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and even more preferably 120 nm to 160 nm. Here, "ny = nz" includes not only the case where ny and nz are exactly equal but also the case where they are substantially equal. Therefore, within a range that does not impair the effects of the present invention, ny > nz or ny < nz may occur.

[0030] The Nz coefficient of the retardation layer is preferably 0.9 to 1.5, more preferably 0.9 to 1.3. By satisfying such a relationship, an organic EL display device having a very excellent reflected hue can be obtained.

[0031] When the retardation layer is a single layer, the retardation layer preferably exhibits an inverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light. In this case, Re(450) / Re(550) of the retardation layer is preferably 0.8 or more and less than 1, more preferably 0.8 or more and 0.95 or less. With such a configuration, very excellent antireflection characteristics can be realized.

[0032] The angle formed by the slow axis of the retardation layer and the absorption axis of the polarizer is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably about 45°. If the angle is within such a range, by using the retardation layer as a λ / 4 plate as described above, an organic EL display device having very excellent antireflection characteristics can be obtained.

[0033] The retardation layer can be composed of any appropriate material as long as it can satisfy the above characteristics. Specifically, the retardation layer may be a stretched film of a resin film or a liquid crystal compound alignment curing layer (hereinafter referred to as a liquid crystal alignment curing layer).

[0034] When the phase difference layer is a stretched resin film, typical examples of the resin constituting the resin film include polycarbonate resins or polyester carbonate resins (hereinafter sometimes simply referred to as polycarbonate resins). Any suitable polycarbonate resin can be used as long as the desired moisture permeability is obtained. For example, a polycarbonate resin includes structural units derived from fluorene-based dihydroxy compounds, structural units derived from isosorbide-based dihydroxy compounds, and structural units derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic dimethanol, di, tri, or polyethylene glycol, and alkylene glycol or spiroglycol. Preferably, the polycarbonate resin comprises structural units derived from fluorene-based dihydroxy compounds, structural units derived from isosorbide-based dihydroxy compounds, structural units derived from alicyclic dimethanol, and / or structural units derived from di, tri, or polyethylene glycol; more preferably, it comprises structural units derived from fluorene-based dihydroxy compounds, structural units derived from isosorbide-based dihydroxy compounds, and structural units derived from di, tri, or polyethylene glycol. The polycarbonate resin may optionally contain structural units derived from other dihydroxy compounds. The phase difference layer can be formed by stretching a film composed of the above-described polycarbonate resin under any suitable stretching conditions. Further details regarding the polycarbonate resin and the method for forming the phase difference layer are described, for example, in Japanese Patent Publication Nos. 2014-10291, 2014-26266, 2015-212816, 2015-212817, 2015-212818, 2017-54093, and 2018-60014. The descriptions in these publications are incorporated herein by reference.

[0035] When the phase difference layer is a liquid crystal alignment solidified layer, using a liquid crystal compound makes the difference between nx and ny in the resulting phase difference layer significantly larger compared to non-liquid crystal materials, thus significantly reducing the thickness of the phase difference layer required to obtain the desired in-plane phase difference. As a result, further thinning of the polarizing plate with a phase difference layer (and consequently, the organic EL display device) can be achieved. In this specification, "alignment solidified layer" refers to a layer in which liquid crystal compounds are oriented in a predetermined direction within the layer, and this orientation state is fixed. Note that "alignment solidified layer" is a concept that includes the orientation hardened layer obtained by hardening liquid crystal monomers. In this embodiment, typically, rod-shaped liquid crystal compounds are oriented in a state aligned along the slow phase axis direction of the phase difference layer (homogenous orientation). Specific examples of liquid crystal compounds and details of the method for forming the liquid crystal alignment solidified layer are described, for example, in Japanese Patent Application Publication No. 2006-163343 and Japanese Patent Application Publication No. 2006-178389. The descriptions in these publications are incorporated herein by reference.

[0036] The thickness of the phase difference layer can typically be set to a thickness that allows it to function appropriately as a λ / 4 plate. If the phase difference layer is a stretched resin film, the thickness of the phase difference layer may be, for example, 10 μm to 60 μm. If the phase difference layer is a liquid crystal alignment solidification layer, the thickness of the phase difference layer may be, for example, 1 μm to 5 μm.

[0037] When the phase difference layer has a laminated structure, the phase difference layer typically has a two-layer structure consisting of a first liquid crystal alignment solidification layer and a second liquid crystal alignment solidification layer. In this case, either the first or the second liquid crystal alignment solidification layer can function as a λ / 2 plate, and the other can function as a λ / 4 plate. Here, we will describe the case where the first liquid crystal alignment solidification layer can function as a λ / 2 plate and the second liquid crystal alignment solidification layer can function as a λ / 4 plate, but these may be reversed. The thickness of the first liquid crystal alignment solidification layer can be adjusted to obtain a desired in-plane phase difference for the λ / 2 plate, for example, 2.0 μm to 4.0 μm. The thickness of the second liquid crystal alignment solidification layer can be adjusted to obtain a desired in-plane phase difference for the λ / 4 plate, for example, 1.0 μm to 2.5 μm. The in-plane phase difference Re(550) of the first liquid crystal alignment solidification layer is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and even more preferably 250 nm to 280 nm. The in-plane phase difference Re(550) of the second liquid crystal alignment solidification layer is, as described above, preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and even more preferably 120 nm to 160 nm. The angle between the slow axis of the first liquid crystal alignment solidification layer and the absorption axis of the polarizer is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably about 15°. The angle between the slow axis of the second liquid crystal alignment solidification layer and the absorption axis of the polarizer is preferably 70° to 80°, more preferably 72° to 78°, and even more preferably about 75°. With such a configuration, it is possible to obtain characteristics close to ideal inverse wavelength dispersion characteristics, and as a result, extremely excellent anti-reflective properties can be realized.

[0038] D. Image display device The polarizing plates with phase difference layers described in sections A to C above can be applied to organic EL display devices. Therefore, embodiments of the present invention encompass organic EL display devices using such polarizing plates with phase difference layers. An organic EL display device according to an embodiment of the present invention is equipped with a polarizing plate with phase difference layers described in sections A to C above on its viewing side. The polarizing plate with phase difference layers is laminated such that the phase difference layer faces the organic EL cell side (the polarizing plate faces the viewing side). In one embodiment, the organic EL display device has a curved shape (substantially a curved display screen) and / or is bendable or foldable. As described above, the inventors discovered a new problem in which the polarizing plate with phase difference layers decolorizes due to ammonia (substantially ammonium ions) generated from the organic EL panel when applied to an organic EL display device, and solved this problem with the polarizing plates with phase difference layers described in sections A to C above. That is, the effect of the polarizing plate with phase difference layers according to an embodiment of the present invention is remarkable in organic EL display devices. [Examples]

[0039] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The measurement methods for each characteristic are as follows. Unless otherwise specified, "parts" and "%" in the examples and comparative examples are based on weight. (1) Thickness Thicknesses of 10 μm or less were measured using an interferometer (Otsuka Electronics Co., Ltd., product name "MCPD-3000"). Thicknesses exceeding 10 μm were measured using a digital micrometer (Anritsu Corporation, product name "KC-351C"). (2) Transmittance and polarization of a single unit For the polarizers used in the examples and comparative examples, the single-plate transmittance Ts, parallel transmittance Tp, and orthogonal transmittance Tc were measured using an ultraviolet-visible spectrophotometer (LPF-2000, manufactured by Otsuka Electronics Co., Ltd.) and were defined as the polarizer's Ts, Tp, and Tc, respectively. These Ts, Tp, and Tc are Y values ​​obtained by measuring under a 2-degree field of view (C light source) according to JIS Z8701 and correcting for luminous sensitivity. From the obtained Tp and Tc, the degree of polarization P was determined using the following formula. Polarization degree P(%)={(Tp-Tc) / (Tp+Tc)} 1 / 2 ×100 (3) Moisture permeability Measurements were taken in accordance with JIS Z 0208. Specifically, the protective layer or phase difference layer (or the film constituting it) used in the examples and comparative examples was cut into a 10 cm diameter circle and used as the measurement sample. The moisture permeability of this measurement sample was measured using Hitachi, Ltd.'s "MOCON" under test conditions of 40°C and 92% RH. (4) Ammonia decolorization test 10 g of a 10% ammonia aqueous solution was placed in a glass bottle (cylindrical, 30 mm in diameter and 50 mm deep). At this time, the distance from the surface of the ammonia aqueous solution to the mouth (top) of the glass bottle was approximately 30 mm. The polarizing plates with phase difference layers obtained in the examples and comparative examples were cut to a size of 15 mm x 15 mm, and an adhesive layer was applied to the phase difference layer side to create the measurement sample. The measurement sample was attached to the rim of the mouth of the glass bottle via the adhesive layer so that it completely covered the mouth of the glass bottle and no vapor leaked through any gaps. The glass bottle covered with the measurement sample was heated at 60°C for 2 hours. The degree of polarization of the polarizing plate with phase difference layer (essentially a polarizer) before heating was P0, and the degree of polarization after heating was P 20 ΔP was calculated using the following formula. A smaller ΔP indicates that decolorization by ammonia is suppressed. ΔP = P 20 -P0

[0040] [Example 1] 1. Fabrication of a polarizer As the thermoplastic resin substrate, an amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) in a long length, with a water absorption rate of 0.75% and a Tg of approximately 75°C was used. One side of the resin substrate was subjected to corona treatment. A PVA aqueous solution (coating solution) was prepared by dissolving 100 parts by weight of a PVA-based resin, which was prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosephymer Z410") in a 9:1 ratio, with 13 parts by weight of potassium iodide. A PVA aqueous solution was applied to the corona-treated surface of a resin substrate and dried at 60°C to form a 13 μm thick PVA-based resin layer, thereby creating a laminate. The resulting laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds in an oven at 130°C (air-assisted stretching). Next, the laminate was immersed for 30 seconds in an insolubilization bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) (insolubilization treatment). Next, the polarizing film was immersed for 60 seconds in a staining bath at a liquid temperature of 30°C (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with 100 parts by weight of water) while adjusting the concentration so that the final polarizing film's single-element transmittance (Ts) was 43.0% (staining treatment). Next, the material was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 40°C (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) (crosslinking treatment). Subsequently, the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4.0 wt%, potassium iodide 5.0 wt%) at a liquid temperature of 70°C, and uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to achieve a total stretch ratio of 5.5 times (underwater stretching treatment). Subsequently, the laminate was immersed in a washing bath at a liquid temperature of 20°C (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (washing treatment). Subsequently, the laminate was dried in an oven maintained at 90°C while being brought into contact with a SUS (stainless steel) heated roll with a surface temperature maintained at 75°C for approximately 2 seconds (drying shrinkage treatment). The shrinkage rate in the width direction of the laminate due to the drying shrinkage treatment was 5.2%. In this way, a polarizer with a thickness of 5 μm was formed on the resin substrate.

[0041] 2. Fabrication of polarizing plates An HC-TAC film was laminated to the polarizer surface of the resin substrate / polarizer laminate obtained above, via an ultraviolet-curing adhesive. Specifically, the curing adhesive was applied to a thickness of 1.0 μm and laminated using a roll machine. Then, UV light was irradiated from the HC-TAC film side to cure the adhesive. The HC-TAC film is a film in which a hard coat (HC) layer (7 μm thick) is formed on a triacetylcellulose (TAC) film (25 μm thick), and it was laminated so that the TAC film was on the polarizer side. Next, the resin substrate was peeled off, and a cycloolefin resin film (13 μm thick: hereinafter referred to as COP film) was laminated to the peeled surface in the same manner as above. The moisture permeability of the HC-TAC film is 427 g / m². 2 • The moisture permeability of the COP film is 35 g / m², and it is 24 hours. 2 The duration was 24 hours. In this way, a polarizing plate having the following configuration was obtained: a viewing-side protective layer (HC-TAC film) / polarizer / another protective layer (COP film).

[0042] 3. Fabrication of the phase difference film constituting the phase difference layer 3-1. Polymerization of polyester carbonate resins Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with stirring blades and reflux condensers controlled to 100°C. The mixture consisted of 29.60 parts by mass (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 29.21 parts by mass (0.200 mol) of isosorbide (ISB), 42.28 parts by mass (0.139 mol) of spiroglycol (SPG), 63.77 parts by mass (0.298 mol) of diphenyl carbonate (DPC), and 1.19 × 10⁻¹⁶ calcium acetate monohydrate as a catalyst. -2 Part of mass (6.78×10 -5A mol (mol) of polymer was added. After purging the reactor with reduced pressure using nitrogen, the reactor was heated with a heat transfer medium, and stirring was started when the internal temperature reached 100°C. Forty minutes after the start of heating, the internal temperature was raised to 220°C, and while controlling the pressure to maintain this temperature, the pressure was reduced to 13.3 kPa 90 minutes after reaching 220°C. The phenol vapor produced as a by-product of the polymerization reaction was directed to a reflux condenser at 100°C, and the monomer components contained in the phenol vapor were returned to the reactor. The uncondensed phenol vapor was directed to a condenser at 45°C and recovered. Nitrogen was introduced into the first reactor to restore the pressure to atmospheric pressure, and then the oligomerized reaction mixture in the first reactor was transferred to the second reactor. Next, heating and depressurization in the second reactor were started, and the internal temperature reached 240°C and the pressure 0.2 kPa in 50 minutes. Polymerization was then allowed to proceed until the predetermined stirring power was reached. Once the predetermined power level was reached, nitrogen was introduced into the reactor to restore pressure, and the resulting polyester carbonate resin was extruded into water. The strands were then cut to obtain pellets.

[0043] 3-2. Preparation of phase difference film The obtained polyester carbonate resin (pellets) was vacuum-dried at 80°C for 5 hours. Then, a long resin film with a thickness of 135 μm was fabricated using a film-making apparatus equipped with a single-screw extruder (Toshiba Machine Co., Ltd., cylinder setting temperature: 250°C), a T-die (width 200 mm, setting temperature: 250°C), a chill roll (setting temperature: 120-130°C), and a winding machine. The obtained long resin film was stretched in the width direction at a stretching temperature of 133°C and a stretching ratio of 2.8 times to obtain a phase difference film with a thickness of 47 μm. The obtained phase difference film had a Re(550) of 141 nm, a Re(450) / Re(550) of 0.82, and an Nz coefficient of 1.12. Furthermore, the moisture permeability of the obtained phase difference film was 75 g / m². 2 It was 24 hours.

[0044] 4. Fabrication of polarizing plates with phase difference layer The phase difference film obtained in 3. above was bonded to the surface of another protective layer (COP film) of the polarizer obtained in 2. above via an acrylic adhesive (thickness 5 μm). At this time, the bonding was carried out so that the absorption axis of the polarizer and the slow phase axis of the phase difference film formed a 45° angle. In this way, a polarizer with a phase difference layer was obtained having the configuration of a visible side protective layer (HC-TAC film) / polarizer / another protective layer (COP film) / adhesive layer / phase difference layer. The total thickness of the obtained polarizer with a phase difference layer was 112 μm. Furthermore, the obtained polarizer with a phase difference layer was subjected to the evaluation in (4) above. The results are shown in Table 1.

[0045] [Example 2] 1. Fabrication of polarizing plates A polarizing plate was fabricated in the same manner as in Example 1.

[0046] 2. Fabrication of the liquid crystal alignment solidification layer constituting the phase difference layer 55 parts of compound (I), 25 parts of compound (II), and 20 parts of compound (III) were added to 400 parts of cyclopentanone (CPN). The mixture was then heated to 60°C and stirred to dissolve. After dissolution was confirmed, the mixture was returned to room temperature. 3 parts of Irgacure 907 (BASF Japan Ltd.), 0.2 parts of Megafac F-554 (DIC Corporation), and 0.1 parts of p-methoxyphenol (MEHQ) were added, and the mixture was further stirred to obtain a solution. The solution was clear and homogeneous. The obtained solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. Meanwhile, the polyimide solution for the alignment film was applied to a 0.7 mm thick glass substrate using a spin coating method, dried at 100°C for 10 minutes, and then fired at 200°C for 60 minutes to obtain a coating film. The obtained coating film was rubbed to form an alignment film. The rubbing process was performed using a commercially available rubbing device. The polymerizable composition obtained above was applied to the substrate (essentially an orientation film) by spin coating and dried at 100°C for 2 minutes. After the resulting coated film was cooled to room temperature, it was heated using a high-pressure mercury lamp at 30 mW / cm². 2A liquid crystal alignment solidification layer was obtained by irradiating with ultraviolet light at the specified intensity for 30 seconds. The in-plane phase difference Re(550) of the liquid crystal alignment solidification layer was 130 nm. Furthermore, the Re(450) / Re(550) of the liquid crystal alignment solidification layer was 0.851, indicating inverse dispersion wavelength characteristics.

[0047] [ka] [ka]

[0048] 3. Fabrication of polarizing plates with phase difference layer The liquid crystal alignment solidification layer obtained in 2. above was transferred to the surface of another protective layer (COP film) of the polarizer obtained in 1. above. At this time, the transfer (lamination) was performed so that the angle between the absorption axis of the polarizer and the slow axis of the liquid crystal alignment solidification layer was 45°. The transfer (lamination) was performed via an ultraviolet-curing adhesive (thickness 1.0 μm). In this way, a polarizer with a phase difference layer having the configuration of a viewing-side protective layer (HC-TAC film) / polarizer / another protective layer (COP film) / adhesive layer / phase difference layer (liquid crystal alignment solidification layer) was obtained. The obtained polarizer with a phase difference layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0049] [Example 3] A polarizing plate with a phase difference layer was obtained in the same manner as in Example 1, except that no additional protective layer was provided. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0050] [Examples 4-6] A polarizing plate with a phase difference layer was obtained using the configuration shown in Table 1, consisting of a viewing-side protective layer, a polarizer, another protective layer, and a phase difference layer. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0051] [Comparative Example 1] A resin substrate / polarizer laminate was prepared in the same manner as in Example 1. An HC-COP film was laminated to the polarizer surface of the obtained resin substrate / polarizer laminate in the same manner as in Example 1. The HC-COP film is a film in which a hard coat (HC) layer (2 μm thick) is formed on a COP film (25 μm thick), and it was laminated so that the COP film was on the polarizer side. Next, the resin substrate was peeled off, and a COP film similar to that in Example 1 was laminated to the peeled surface in the same manner as in Example 1. The moisture permeability of the HC-COP film was 17 g / m². 2 • The moisture permeability of the COP film is 35 g / m², and it is 24 hours. 2 The time was 24 hours. In this way, a polarizing plate having the configuration of a viewing-side protective layer (HC-COP film) / polarizer / another protective layer (COP film) was obtained. The following procedure was the same as in Example 1 to obtain a polarizing plate with a phase difference layer. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0052] [Comparative Examples 2-10] A polarizing plate with a phase difference layer was obtained using the configuration shown in Table 1, consisting of a viewing-side protective layer, a polarizer, another protective layer, and a phase difference layer. The obtained polarizing plate with a phase difference layer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0053] [Table 1]

[0054] [evaluation] As is clear from Table 1, according to the embodiments of the present invention, a polarizing plate with a phase difference layer that hardly changes in polarization degree (i.e., does not decolorize) even when exposed to ammonia can be obtained. In other words, according to the embodiments of the present invention, it is possible to realize a polarizing plate with a phase difference layer that suppresses decolorization when applied to an organic EL display device. On the other hand, the polarizing plates with phase difference layers of the comparative examples show a significant decrease in polarization function, and in the majority of them, the polarization function is almost completely lost. [Industrial applicability]

[0055] The polarizing plate with a phase difference layer of the present invention is suitably used as an anti-reflective circular polarizing plate for organic EL display devices. [Explanation of symbols]

[0056] 10 Polarizing plates 11 Polarizer 12 Protective layer 13 Protective layer 20 Retardation layer 100 Polarizing plate with retardation layer

Claims

1. A polarizing plate comprising a polarizer and a protective layer at least on the viewing side of the polarizer, and a phase difference layer disposed on the opposite side of the viewing side of the polarizing plate, The thickness of the polarizer is 8 μm or less. The phase difference layer is an orientation solidification layer of a liquid crystal compound. The phase difference layer has a Re(550) wavelength of 100 nm to 190 nm, and a Re(450) / Re(550) ratio of 0.8 or more and less than 1. The angle between the slow axis of the phase difference layer and the absorption axis of the polarizer is 40° to 50°. The moisture permeability of the protective layer on the visible side is 200 g / m². ２ - It is 24 hours or longer, and is greater than the moisture permeability of the phase difference layer. Polarizing plate with retardation layer.

2. The polarizing plate further includes another protective layer on the side opposite to the viewing side of the polarizer, The moisture permeability of the visible protective layer is greater than that of the other protective layer. A polarizing plate with a phase difference layer according to claim 1.

3. The polarizing plate with a phase difference layer according to claim 1 or 2, wherein the difference between the moisture permeability of the protective layer on the viewing side and the moisture permeability of the phase difference layer is 200 g / m²・24h or more.

4. A polarizing plate with a phase difference layer according to any one of claims 1 to 3, wherein the total thickness is 20 μm or more and 100 μm or less.

5. An organic electroluminescent display device comprising a polarizing plate with a phase difference layer according to any one of claims 1 to 4.

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