Polarizing plate with phase retardation layer and organic electroluminescent display device using it

Abstract

This invention provides a polarizing plate with a phase retardation layer, which significantly suppresses color loss when applied to an organic EL display device. The polarizing plate with a phase retardation layer according to an embodiment of this invention has a polarizing element and a blocking layer disposed on one side of the polarizing element and including the phase retardation layer, wherein the ammonia permeation of the blocking layer is 70 g / m²·24h or less.

Description

[Technical Field]

[0001] This invention relates to a polarizing plate with a phase retardation layer and an organic electroluminescence (EL) display device using the same. [Previous Technology]

[0002] In recent years, with the popularization of thin-film displays, displays equipped with organic EL panels (organic EL display devices) have been disclosed. Because organic EL panels have a highly reflective metal layer, they are prone to problems such as external light reflection and background reflection. Therefore, methods to prevent these problems by providing a circular polarizer on the viewing side are known (e.g., Patent Document 1 and Patent Document 2). However, the circular polarizer provided in the organic EL display device is prone to color fading. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2002-372622 [Patent Document 2] Japanese Patent Publication No. 3325560 [Summary of the Invention]

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

[0005] This invention was made to solve the aforementioned problems, and its main objective is to provide a polarizing plate with a phase retardation layer, which significantly suppresses color loss when applied to an organic EL display device. [Technical Means for Solving the Problem]

[0006] According to an embodiment of the present invention, a polarizing plate with a phase retardation layer is provided. The polarizing plate with a phase retardation layer has a polarizing element and a blocking layer disposed on one side of the polarizing element and including the phase retardation layer, wherein the ammonia transmission rate of the blocking layer is 70 g / m²·24h or less. In one embodiment, the ammonia transmission rate of the phase retardation layer is 70 g / m²·24h or less. In one embodiment, the blocking layer includes a protective layer for the polarizing element. In one embodiment, the ammonia transmission rate of the protective layer is 70 g / m²·24h or less. In one embodiment, the polarizing plate with a phase retardation layer has a protective layer disposed on the other side of the polarizing element. In one embodiment, the transmittance of a single polarizing element is 40% or more and 45% or less. In one embodiment, the Re(450) / Re(550) ratio of the phase retardation layer is 0.8 or more and less than 1. In one embodiment, the thickness of the polarizing element is 10 μm or less. In one embodiment, the thickness of the polarizing plate with the retardation layer is 150 μm or less. According to another aspect of the present invention, an organic electroluminescent display device is provided. This organic electroluminescent display device has the aforementioned polarizing plate with the retardation layer. [Effects of the Invention]

[0007] According to an embodiment of the present invention, in a polarizing plate with a phase retardation layer, by providing a layer that satisfies a specific ammonia gas transmission amount on one side of the polarizing element, a polarizing plate with a phase retardation layer can be realized in the case of application to an organic EL display device, in which color loss is significantly suppressed.

Implementation Method

[0009] The embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

[0010] (Definitions of Terms and Symbols) The terms and symbols used in this specification are defined as follows. (1) Refractive Index (nx, ny, nz) "nx" refers to the refractive index in the direction where the in-plane refractive index reaches its maximum (i.e., the direction of the late phase axis), "ny" refers to the refractive index in the direction orthogonal to the late phase axis (i.e., the direction of the advanced phase axis), and "nz" refers to the refractive index in the thickness direction. (2) In-plane Phase Difference (Re) "Re(λ)" refers to the in-plane phase difference measured at 23°C using light with a wavelength of λ nm. For example, "Re(550)" refers to the in-plane phase difference measured at 23°C using light with a wavelength of 550 nm. Re(λ) is calculated by the formula: Re(λ)=(nx-ny)×d when the thickness of the layer (film) is set to d (nm). (3) Phase difference in the thickness direction (Rth) "Rth(λ)" is the phase difference in the thickness direction measured at 23°C using light with a wavelength of λ nm. For example, "Rth(550)" is the phase difference in the thickness direction measured at 23°C using light with a wavelength of 550 nm. Rth(λ) is calculated using the formula: Rth(λ)=(nx-nz)×d when the thickness of the layer (film) is set to d (nm). (4) Nz coefficient The Nz coefficient is calculated using Nz=Rth / Re. (5) Angle When an angle is mentioned in this specification, the angle includes both clockwise and counterclockwise directions relative to the reference direction. Therefore, for example, "45°" means ±45°.

[0011] A. Polarizing Plate with Phase Retardation Layer FIG. 1 is a schematic cross-sectional view showing the schematic configuration of a polarizing plate with phase retardation layer according to one embodiment of the present invention. The polarizing plate 100 with phase retardation layer has a polarizing element 11, a protective layer (viewing-side protective layer) 12 disposed on the viewing side of the polarizing element 11, and a blocking layer 30 disposed on the side opposite to the viewing side of the polarizing element 11. The blocking layer 30 sequentially includes the protective layer (inner protective layer) 13 of the polarizing element 11 and the phase retardation layer 20 from the viewing side. Thus, the protective layer 13 is disposed on the side opposite to the viewing side of the polarizing element 11, and the protective layer 13 can be omitted depending on the purpose, etc. Specifically, the blocking layer 30 may also not include the protective layer 13. For example, when the phase retardation layer 20 is composed of an extended film of a resin film and can also serve as a protective layer for the polarizing element, the protective layer 13 can also be omitted. On the other hand, when the retardation layer 20 is an alignment and curing layer of a liquid crystal compound, a protective layer 13 is typically disposed thereon. The retardation layer 20 can be a single layer or a multilayer structure with two or more layers. Furthermore, the multilayer of the polarizing element and the protective layer is referred to as a polarizing plate. In the example shown, the polarizing plate 10 has a polarizing element 11 and protective layers 12 and 13.

[0012] The thickness of the polarizing plate with the retardation layer (from the viewing-side protective layer to the retardation layer) is preferably 150 μm or less, more preferably 120 μm or less, further preferably 100 μm or less, and particularly preferably 80 μm or less. The lower limit of the thickness of the polarizing plate with the retardation layer is preferably 20 μm, more preferably 45 μm. Such a polarizing plate with a retardation layer can, for example, have excellent flexibility and bending durability. As a result, the polarizing plate with the retardation layer can be used in organic EL display devices that can be bent, flexed, folded, rolled, etc.

[0013] Although not illustrated, the polarizing plate with a phase retardation layer may further have other functional layers. The type, characteristics, quantity, combination, and configuration of the functional layers that the polarizing plate with a phase retardation layer may have can be appropriately set according to the purpose. For example, the polarizing plate with a phase retardation layer may further have a conductive layer or an isotropic substrate with a conductive layer. A polarizing plate with a phase retardation layer having a conductive layer or an isotropic substrate with a conductive layer is used, for example, in an organic EL display device in which a touch sensor is assembled inside an organic EL panel. As another example, the polarizing plate with a phase retardation layer may further have other phase retardation layers. The optical characteristics (e.g., refractive index characteristics, in-plane phase retardation, Nz coefficient, optical elasticity coefficient), thickness, and configuration of other phase retardation layers can be appropriately set according to the purpose. As a specific example, on the viewing side of the polarizing plate 10, other phase retardation layers (typically, layers that impart (ellipsoidal) polarization to light and layers that impart ultra-high phase retardation) can also be provided to improve visibility when viewed through polarized sunglasses. By having such layers, excellent visibility can be achieved even when viewing the displayed image through polarized lenses such as polarized sunglasses. Therefore, the obtained polarizing plate (polarizing plate with phase retardation layer) can also be better applied to image display devices that can be used outdoors.

[0014] The components constituting the polarizing plate with the retardation layer can be laminated via any suitable adhesive layer (not shown). Specific examples of adhesive layers include adhesive layers and bonding agents. Specifically, the retardation layer 20 can be bonded to the polarizing element 11 or the protective layer 13 via an adhesive layer (preferably using an active energy line curing adhesive), or via an adhesive layer (e.g., an acrylic adhesive). When the retardation layer 20 has a laminated structure with two or more layers, each retardation layer is bonded via, for example, an adhesive layer (preferably using an active energy line curing adhesive). The blocking layer 30 may also include an adhesive layer disposed between the polarizing element 11 and the retardation layer 20.

[0015] Although not shown in the figure, for practical purposes, an adhesive layer is provided on the side of the retardation layer 20 opposite to the side where the polarizing element 11 is disposed (specifically, the outermost layer opposite to the viewing side), so that the polarizing plate with the retardation layer attached can be attached to the organic EL panel body. Furthermore, it is preferable to temporarily attach a release film (isolation film) to the surface of the adhesive layer before the polarizing plate with the retardation layer is used. By temporarily attaching the isolation film, the polarizing plate with the retardation layer attached can be rolled up while protecting the adhesive layer.

[0016] The polarizing plate with the retardation layer can be elongated or in single-piece form. Here, "elongated" refers to a long and thin shape with a length that is sufficiently long relative to its width, for example, a long and thin shape with a length that is more than 10 times, preferably more than 20 times, relative to its width. The elongated polarizing plate with the retardation layer can be rolled into a cylindrical shape.

[0017] A-1. The ammonia permeation rate of the blocking layer 30 is 70 g / m²·24h or less, preferably 60 g / m²·24h or less, more preferably 50 g / m²·24h or less, further preferably 40 g / m²·24h or less, and particularly preferably 30 g / m²·24h or less. By providing this blocking layer, discoloration can be significantly suppressed. The inventors directly faced the new problem of discoloration occurring when a polarizing plate with a phase retardation layer is applied to an organic EL display device, and conducted intensive research on this problem. As a result, they found that the cause of discoloration is ammonia (essentially ammonium ions) from the components constituting the organic EL panel. By using this blocking layer 30, ammonia reaching the polarizing element is blocked as much as possible, thereby significantly suppressing discoloration. Specifically, the decomposition of dichroic substances (representatively iodine complexes) contained in the polarizing element can be suppressed. The ammonia permeation rate of the barrier layer 30 is, for example, 3.0 g / m2·24h or more.

[0018] The ammonia permeability of the barrier layer 30 can be achieved by at least one layer included in the barrier layer 30, or by a combination of two or more layers included in the barrier layer 30. Specifically, the ammonia permeability of the barrier layer 30 can be achieved by the protective layer 13 of the polarizing element 11, or by the phase retardation layer 20, or by the aforementioned adhesive layer (e.g., an adhesive layer), or by a combination thereof. In one embodiment, the ammonia permeability of either the phase retardation layer 20 or the protective layer 13 is 70 g / m²·24h or less.

[0019] The above-mentioned ammonia permeation rate can be obtained by measuring the permeation rate of ammonia solution and the permeation rate of water, and then calculating the difference between them.

[0020] A-2. Polarizing element The polarizing element described above is a film containing a dichroic substance (represented by iodine).

[0021] Regarding the thickness of the polarizing element, from the viewpoint of thinning, it is preferably 15 μm or less, more preferably 12 μm or less, and even more preferably 10 μm or less, and particularly preferably 8 μm or less. On the other hand, the thickness of the polarizing element is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more. If the thickness of the polarizing element is within this range, for example, shrinkage during heating can be well suppressed, and good appearance durability during heating can be obtained.

[0022] The polarizing element preferably exhibits dichroic absorption at any wavelength from 380 nm to 780 nm. The transmittance of a single element is, for example, 40.0% or more, preferably 41.5% or more, more preferably 43.0% or more, and even more preferably 44.5% or more. Alternatively, the transmittance may be, for example, 46.0% or less, or even 45.0% or less. The polarization degree of the polarizing element is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

[0023] The polarizing element can be manufactured by any suitable method. Specifically, the polarizing element can be made from a single layer of resin film or from a laminate of two or more layers.

[0024] The method described above for manufacturing a polarizing element from a single-layer resin film typically involves dyeing and stretching the resin film using dichroic substances such as iodine or dichroic dyes. For example, hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films are used. From the perspective of superior optical properties, it is preferable to obtain the polarizing element by dyeing the PVA film with iodine and uniaxially stretching it.

[0025] The above-mentioned dyeing with iodine can be carried out, for example, by immersing the PVA membrane in an aqueous iodine solution. The preferred uniaxial stretching ratio is 3 to 7 times. Stretching can be performed after dyeing or simultaneously with dyeing. Alternatively, stretching can be performed before dyeing. Swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc., can be applied to the PVA membrane as needed. For example, by immersing the PVA membrane in water for washing before dyeing, not only can dirt and anti-blocking agents on the surface of the PVA membrane be washed away, but the PVA membrane can also swell, thereby preventing uneven dyeing.

[0026] As a specific example of the polarizing element obtained by using the above-described laminate, examples include a laminate containing a resin substrate and a PVA-based resin layer (PVA-based resin film) deposited on the resin substrate, or a polarizing element obtained by using a resin substrate and a laminate coated with a PVA-based resin layer formed on the resin substrate. A polarizing element obtained by using a resin substrate and a laminate coated with a PVA-based resin layer formed on the resin substrate can be manufactured, for example, by the following steps: coating a PVA-based resin solution onto a resin substrate, drying it to form a PVA-based resin layer on the resin substrate, obtaining a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to form a polarizing element from the PVA-based resin layer. In this embodiment, it is preferable to form a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin on one side of the resin substrate. Stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, the extension process may be further performed by air-stretching the laminate at a high temperature (e.g., above 95°C) before being extended in a boric acid aqueous solution, as needed. Additionally, in this embodiment, it is preferable to subject the laminate to a drying shrinkage treatment, which involves heating one side while conveying it along its long side to shrink it by 2% or more in its width direction. Typically, the manufacturing method of this embodiment includes sequentially applying an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment to the laminate. By introducing assisted stretching, even when PVA is coated onto a thermoplastic resin, the crystallinity of PVA can be improved, resulting in higher optical properties. Furthermore, by simultaneously improving the alignment of PVA beforehand, problems such as decreased alignment and dissolution of PVA can be prevented during subsequent dyeing and stretching steps when immersed in water, thereby achieving higher optical properties. Furthermore, when the PVA-based resin layer is immersed in a liquid, compared to when the PVA-based resin layer does not contain halides, the orientation disorder of polyvinyl alcohol molecules and the decrease in orientation can be suppressed. This improves the optical properties of the polarizing element obtained by immersing the laminate in a liquid through dyeing and water-stretching processes. Furthermore, by shrinking the laminate in the width direction through a drying shrinkage process, optical properties can be further improved. The obtained resin substrate / polarizing element laminate can be used directly (i.e., the resin substrate can be used as a protective layer for the polarizing element), or it can be used after peeling off the release surface of the resin substrate from the resin substrate / polarizing element laminate, or after applying any suitable protective layer to the side opposite the release surface according to the desired deposition. Detailed descriptions of this method for manufacturing a polarizing element are provided, 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.

[0027] A-3. Protective Layer The aforementioned protective layer is composed of any suitable film that can be used as a protective layer for a polarizing element. Examples of materials constituting the protective layer include: cellulose resins such as triacetyl cellulose (TAC), cyclic olefin resins such as polynorcamphene, (meth)acrylic resins, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene, and polycarbonate resins. As a representative example of (meth)acrylic resins, (meth)acrylic resins having a lactone ring structure can be cited. (Meth)acrylic resins having a lactone ring structure are described, for example, in Japanese Patent Application Publication Nos. 2000-230016, 2001-151814, 2002-120326, 2002-254544, and 2005-146084. These publications are incorporated herein by reference.

[0028] A polarizing plate with a phase difference layer is typically disposed on the viewing side of an organic EL display device. The viewing side protective layer 12 can also be subjected to surface treatments such as hard coating, anti-reflection treatment, anti-adhesion treatment, and anti-glare treatment as needed.

[0029] The thickness of the viewing-side protective layer 12 can be appropriately set. The thickness of the viewing-side 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. Furthermore, when a surface treatment is performed, the thickness of the viewing-side protective layer 12 includes the thickness of the surface treatment layer.

[0030] In one embodiment, the ammonia permeation rate of the protective layer 13 is 70 g / m²·24h or less, preferably 60 g / m²·24h or less, more preferably 50 g / m²·24h or less, further preferably 40 g / m²·24h or less, and most preferably 30 g / m²·24h or less. In this case, the material constituting the protective layer 13 is preferably at least one selected from cellulose resins, cycloolefin resins, and polyester resins.

[0031] 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 be appropriately set, for example, according to the desired ammonia permeation. 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. When the phase retardation layer 20 is an extension of the resin film, for example, from the viewpoint of thinning, the protective layer 13 can also be omitted.

[0032] A-4. Phase difference layer The phase difference layer 20 can be a single layer or have a stacked structure (essentially a two-layer structure).

[0033] When the retardation layer 20 is a single layer, the retardation layer 20 is characterized by its ability to function as a λ / 4 plate. The retardation layer is characterized by its provision of anti-reflective properties to the organic EL display device. The retardation layer is characterized by its refractive index characteristics exhibiting a relationship of nx > ny = nz. The in-plane phase difference 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. Furthermore, "ny = nz" here refers not only to the case where ny and nz are exactly equal, but also to the case where they are substantially equal. Therefore, without impairing the effects of the present invention, there may be cases where ny > nz or ny < nz.

[0034] The Nz coefficient of the phase retardation layer is preferably 0.9 to 1.5, and more preferably 0.9 to 1.3. By satisfying this relationship, an organic EL display device with very excellent reflective hue can be obtained.

[0035] When the retardation layer is a single layer, it is preferable that the retardation layer exhibits a reverse wavelength dispersion characteristic, where the phase difference value increases according to the wavelength of the measured light. In this case, the Re(450) / Re(550) of the retardation layer is preferably 0.8 or higher and less than 1, more preferably 0.8 or higher and less than 0.95. With this configuration, very excellent anti-reflection properties can be achieved.

[0036] The angle between the late phase axis of the retardation layer and the absorption axis of the polarizing element is preferably 40° to 50°, more preferably 42° to 48°, and even more preferably about 45°. If the angle is within this range, an organic EL display device with excellent anti-reflection properties can be obtained by setting the retardation layer as a λ / 4 plate as described above.

[0037] The phase retardation layer can be made of any suitable material as long as it meets the characteristics described above. Specifically, the phase retardation layer can be an extension film of a resin film or an alignment and curing layer of a liquid crystal compound (hereinafter referred to as a liquid crystal alignment and curing layer).

[0038] When the phase difference layer is an extension of the resin film, representative examples of the resin constituting the resin film include polycarbonate resins or polyester carbonate resins (hereinafter sometimes simply referred to as polycarbonate resins). As a polycarbonate resin, any suitable polycarbonate resin can be used as long as the required moisture permeability is obtained. For example, a polycarbonate resin may contain: structural units derived from benzoyl dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from at least one dihydroxy compound selected from the group consisting of alicyclic diols, alicyclic diethanols, di-, tri-, or polyethylene glycols, and alkyl diols or spirodiols. The polycarbonate resin preferably comprises: structural units derived from genus dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, structural units derived from alicyclic diethanol, and / or structural units derived from di, tri, or polyethylene glycol; more preferably, it comprises: structural units derived from genus dihydroxy compounds, structural units derived from isosorbide dihydroxy compounds, and structural units derived from di, tri, or polyethylene glycol. The polycarbonate resin may also, if necessary, comprise structural units derived from other dihydroxy compounds. The retardation layer can be formed by stretching a film composed of the polycarbonate resin described above under any suitable stretching conditions. Furthermore, detailed descriptions of the polycarbonate resin and the method for forming the retardation layer are found in, for example, Japanese Patent Application Publication Nos. 2014-10291, 2014-26266, 2015-212816, 2015-212817, 2015-212818, 2017-54093, and 2018-60014. These publications are incorporated herein by reference.

[0039] When the retardation layer is a liquid crystal alignment and curing layer, by using a liquid crystal compound, the difference between nx and ny of the obtained retardation layer can be significantly increased compared to non-liquid crystal materials. Therefore, the thickness of the retardation layer used to obtain the desired in-plane retardation can be significantly reduced. As a result, the polarizing plate with the retardation layer (resulting in an organic EL display device) can be further thinned. In this specification, "alignment and curing layer" refers to a layer in which a liquid crystal compound is aligned in a specific direction within the layer, and its alignment state is fixed. Furthermore, "alignment and curing layer" includes the concept of an alignment-cured layer obtained by curing liquid crystal monomers. In this embodiment, it is representative that rod-shaped liquid crystal compounds are aligned (horizontal alignment) in a state of being arranged in the late phase axis direction of the retardation layer. Specific examples of liquid crystal compounds and detailed methods for forming liquid crystal alignment and curing layers are described, for example, in Japanese Patent Application Publication Nos. 2006-163343 and 2006-178389. The descriptions in these publications are incorporated herein by reference.

[0040] The thickness of the retardation layer is representative of a thickness that can be set to allow it to function appropriately as a λ / 4 plate. When the retardation layer is an extension film of a resin film, the thickness of the retardation layer can be, for example, 10 μm to 60 μm. When the retardation layer is a liquid crystal alignment and curing layer, the thickness of the retardation layer can be, for example, 1 μm to 5 μm.

[0041] When the retardation layer 20 has a multilayer structure, the retardation layer is typically a two-layer structure having a first liquid crystal alignment and curing layer and a second liquid crystal alignment and curing layer. In this case, either the first liquid crystal alignment and curing layer or the second liquid crystal alignment and curing layer can function as a λ / 2 plate, and the other can function as a λ / 4 plate. Here, the case where the first liquid crystal alignment and curing layer functions as a λ / 2 plate and the second liquid crystal alignment and curing layer functions as a λ / 4 plate will be described, but the reverse is also possible. The thickness of the first liquid crystal alignment and curing layer can be adjusted to obtain the in-plane phase difference required for the λ / 2 plate, for example, it can be 2.0 μm to 4.0 μm. The thickness of the second liquid crystal alignment and curing layer can be adjusted to obtain the in-plane phase difference required for the λ / 4 plate, for example, it can be 1.0 μm to 2.5 μm. The in-plane phase difference Re(550) of the first liquid crystal alignment and curing 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 and curing layer, as described above, is 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 late phase axis of the first liquid crystal alignment and curing layer and the absorption axis of the polarizing element is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably about 15°. The angle between the late phase axis of the second liquid crystal alignment and curing layer and the absorption axis of the polarizing element is preferably 70° to 80°, more preferably 72° to 78°, and even more preferably about 75°. With this configuration, characteristics close to the ideal reverse wavelength dispersion can be obtained, resulting in excellent anti-reflection properties.

[0042] In one embodiment, the ammonia permeation rate of the phase retardation layer 20 is 70 g / m²·24h or less, preferably 60 g / m²·24h or less, more preferably 50 g / m²·24h or less, further preferably 40 g / m²·24h or less, and most preferably 30 g / m²·24h or less. In this case, the phase retardation layer 20 is preferably an extension of the aforementioned resin film. As for the constituent material of the protective layer 13 combined with the phase retardation layer 20, which is an extension of the resin film, it is preferably at least one selected from cycloolefin resins and polyester resins. With this combination, discoloration can be significantly suppressed.

[0043] As for the material constituting the protective layer 13, which is combined with the phase retardation layer 20 as the liquid crystal alignment and curing layer, it is preferable to use a cellulose-based resin. With this combination, discoloration can be significantly suppressed.

[0044] B. The polarizing plate with the aforementioned phase retardation layer can be applied to an organic EL display device. Therefore, the organic EL display device according to an embodiment of the present invention has the aforementioned polarizing plate with the aforementioned phase retardation layer.

[0045] FIG2 is a schematic cross-sectional view showing a polarizing plate with a phase retardation layer disposed on an organic EL display device according to one embodiment of the present invention. The polarizing plate 100 with the phase retardation layer is disposed such that its blocking layer 30 is closer to the organic EL panel body 40 than the polarizing element 11. Specifically, the polarizing plate 100 with the phase retardation layer is attached to the organic EL panel body 40 via an adhesive layer (not shown). The organic EL panel body 40 has a substrate 60 and an upper structural layer 80, wherein the upper structural layer 80 includes: a circuit layer including a thin-film transistor (TFT), an organic light-emitting diode (OLED), and a sealing film sealing the OLED. The upper structural layer 80 contains, for example, a nitrogen-containing layer (e.g., a nitride layer), and ammonia (ammonium) may be generated from the upper structural layer 80. By using the aforementioned polarizing plate with a phase retardation layer, color fading can be significantly suppressed in organic EL display devices. Furthermore, the color fading problem can be solved without changing the design of the organic EL panel itself.

[0046] For example, when a flexible substrate (e.g., a resin substrate) is used as the substrate 60, the resulting organic EL display device can be bent, flexed, folded, rolled, etc. [Example]

[0047] The present invention will be specifically described below by way of examples, but the present invention is not limited to these examples. The methods for measuring each characteristic are described below. In addition, unless otherwise specified, “parts” and “%” in the examples and comparative examples are based on weight. (1) Thickness of less than 10 μm was measured using an interferometric film thickness gauge (manufactured by Otsuka Electronics Co., Ltd., product name “MCPD-3000”). Thickness of more than 10 μm was measured using a digital micrometer (manufactured by Anritsu Co., Ltd., product name “KC-351C”). (2) Ammonia permeation: Two cups A and B were prepared. 150 g of 10% ammonia solution was added to cup A and 150 g of water was added to cup B. The cups were sealed with a test piece (film) cut into a circle with a diameter of 6 cm. Under this condition, cups A and B were placed in an oven set at 40°C (atmospheric pressure) for 24 hours, and the weight change of cups A and B before and after standing was measured. Calculate the difference between the weight change of cup A (the amount of ammonia and water passing through) and the weight change of cup B (the amount of water passing through), and then determine the amount of ammonia passing through (g / m2・24h).

[0048] [Example 1] 1. Fabrication of polarizing element: A strip-shaped amorphous polyethylene terephthalate copolymer film (thickness: 100 μm) with a water absorption rate of 0.75% and a Tg (glass transition temperature) of approximately 75°C was used as the thermoplastic resin substrate. One side of the resin substrate was subjected to corona treatment. 13 parts by weight of potassium iodide were added to 100 parts by weight of a PVA-based resin obtained by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetylacetoyl modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z410") in a 9:1 ratio, and dissolved in water to prepare a PVA aqueous solution (coating solution). The above PVA aqueous solution was coated on the corona-treated side of the resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13 μm, thereby fabricating a laminate. The obtained laminate was uniaxially extended 2.4 times at its free end in the longitudinal direction (long side direction) between rollers at different circumferential speeds in an oven at 130°C (air-assisted extension treatment). Next, the laminate was immersed in an insoluble bath (a boric acid aqueous solution prepared by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at 40°C for 30 seconds (insoluble treatment). Then, the concentration of the dyeing bath (an iodine aqueous solution prepared by mixing iodine and potassium iodide in a 1:7 weight ratio with 100 parts by weight of water) at 30°C was adjusted to achieve a single transmittance (Ts) of 43.0% for the final polarizing film, and the laminate was immersed in it for 60 seconds (dyeing treatment). Finally, the laminate was immersed in a crosslinking bath (a boric acid aqueous solution prepared by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with 100 parts by weight of water) at 40°C for 30 seconds (crosslinking treatment). Subsequently, the laminate was immersed in a boric acid aqueous solution (4.0 wt% boric acid, 5.0 wt% potassium iodide) at 70°C, while being uniaxially stretched longitudinally (long side direction) between rollers at different circumferential speeds to achieve a total elongation of 5.5 times (water stretching treatment). Then, the laminate was immersed in a washing bath at 20°C (an aqueous solution of 4 wt% potassium iodide to 100 wt% water) (washing treatment). Next, it was dried in an oven maintained at 90°C while being brought into contact with a SUS (Steel Use Stainless) heated roller with a surface temperature maintained at 75°C for approximately 2 seconds (drying shrinkage treatment). The width shrinkage of the laminate after the drying shrinkage treatment was 5.2%. In this manner, a polarizing element with a thickness of 5 μm was formed on a resin substrate.

[0049] 2. The polarizing plate is fabricated by bonding a 25 μm thick TAC film to the surface of the resin substrate / polarizing element laminate obtained by the above steps using an ultraviolet-curing adhesive. Specifically, the curing adhesive is applied to a thickness of 1.0 μm and then bonded using a roller press. Subsequently, UV (Ultraviolet) light is irradiated from one side of the TAC film to cure the adhesive. Then, the resin substrate is peeled off from the polarizing element, and a cyclic olefin resin film (13 μm thick, ammonia permeability 54 g / m2・24h: hereinafter referred to as COP (Cyclo Olefin Polymer) film) is bonded to the peeled surface in the same manner as described above. In this way, a polarizing plate having a TAC film / polarizing element / COP film is obtained.

[0050] 3. Fabrication of the phase retardation film constituting the phase retardation layer 3-1. Polymerization of polyester carbonate resin was carried out using a batch polymerization apparatus containing two longitudinally arranged reactors. The longitudinally arranged reactors were equipped with stirring blades and a reflux condenser controlled at 100°C. 29.60 parts by mass (0.046 mol) of bis[9-(2-phenoxycarbonylethyl)furan-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 × 10⁻² parts by mass (6.78 × 10⁻⁵ mol) of calcium acetate monohydrate as a catalyst were added. After purging the reactor with nitrogen under reduced pressure, heating is applied using a heating medium, and stirring begins when the internal temperature reaches 100°C. Forty minutes after the start of heating, the internal temperature reaches 220°C, and while maintaining this temperature, pressure is reduced until it reaches 13.3 kPa after 90 minutes. Phenolic vapors, a byproduct of the polymerization reaction, are directed to a 100°C reflux condenser, allowing some monomer components contained in the phenol vapors to return to the reactor. Uncondensed phenol vapors are then directed to a 45°C condenser for recovery. Nitrogen is introduced into the first reactor to temporarily restore the pressure to atmospheric pressure, and the oligomerized reaction liquid from the first reactor is transferred to the second reactor. Heating and depressurization are then initiated in the second reactor, reaching an internal temperature of 240°C and a pressure of 0.2 kPa within 50 minutes. Polymerization then continues until a specific stirring force is achieved. Nitrogen gas is introduced into the reactor at a specific time point when the power is reached, and the pressure is repressurized to extrude the generated polyester carbonate resin into the water, cutting the wire to obtain particulate matter.

[0051] 3-2. Fabrication of the Phase Retardation Film The obtained polyester carbonate resin (particulate matter) was vacuum dried at 80°C for 5 hours. A film-forming apparatus equipped with a single-shaft extruder (manufactured by Toshiba Machine Co., Ltd., cylinder set temperature: 250°C), a T-die (width 200 mm, set temperature: 250°C), a cooling roller (set temperature: 120-130°C), and a winding machine was used to fabricate a strip-shaped resin film with a thickness of 135 μm. The obtained strip-shaped resin film was stretched in the width direction at a stretching temperature of 133°C and a stretch ratio of 2.8 times to obtain a phase retardation film with a thickness of 47 μm. The obtained phase retardation film had a Re(550) of 141 nm, a Re(450) / Re(550) ratio of 0.82, and an Nz coefficient of 1.12. Furthermore, the ammonia permeation rate of the obtained phase retardation film was 10 g / m²·24h.

[0052] 4. Preparation of Adhesive 4-1. Preparation of Acrylic Polymer A monomer mixture containing 91 parts butyl acrylate, 6 parts acrylonitrile (ACMO, 4-acryloylmorpholine), 2.7 parts acrylic acid, and 0.3 parts 4-hydroxybutyl acrylate was added to a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a condenser. Then, relative to 100 parts of the monomer mixture, 0.1 parts of 2,2'-azobisisobutyronitrile (2,2'-azobisisobutyronitrile) as a polymerization initiator and 100 parts of ethyl acetate were added together. After nitrogen purging while slowly stirring, the liquid temperature in the flask was maintained at around 55°C and the polymerization reaction was carried out for 8 hours to prepare an acrylic polymer solution.

[0053] 4-2. Preparation of the adhesive: For 100 parts of the solid content of the obtained acrylic polymer solution, 0.1 parts of trimethylolpropane / toluene diisocyanate adduct (manufactured by Tosoh Corporation, trade name "Coronate L"), 0.3 parts of peroxide crosslinking agent (benzoyl peroxide), and 0.2 parts of epoxy-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") were added to obtain the adhesive. The ammonia permeation of the obtained adhesive (20 μm thickness) was 118 g / m²·24h.

[0054] 5. A polarizing plate with a retardation layer is fabricated by bonding the retardation film obtained in step 2 to the COP film surface of the polarizing plate obtained in step 3 using the adhesive obtained in step 4 (20 μm thick). At this time, the bonding is performed at a 45° angle between the absorption axis of the polarizing element and the lag axis of the retardation film. A polarizing plate with a retardation layer is obtained in this manner.

[0055] [Example 2] In the fabrication of the polarizing plate, a PET film (thickness 30 μm, ammonia permeability 53 g / m2・24h) was used instead of a COP film, and otherwise the same procedure was performed as in Example 1 to obtain a polarizing plate with a phase retardation layer.

[0056] [Example 3] In the fabrication of the polarizing plate, a TAC film (thickness 25 μm, ammonia permeation 30 g / m2・24h) was used instead of a COP film, and otherwise the same procedure was performed as in Example 1 to obtain a polarizing plate with a phase retardation layer.

[0057] [Example 4] In the fabrication of the polarizing plate, an acrylic resin film with an lactone ring structure (thickness 20 μm, ammonia permeation 78 g / m2・24h) was used instead of the COP film. Otherwise, the process was the same as in Example 1 to obtain a polarizing plate with a phase retardation layer.

[0058] [Example 5] In the fabrication of the polarizing plate, the COP film was not bonded to the polarizing element using an ultraviolet curing adhesive. Otherwise, the process was the same as in Example 1 to obtain a polarizing plate with a phase retardation layer.

[0059] [Example 6] The following liquid crystal alignment curing layer was used as the phase retardation layer, and the process was carried out in the same manner as in Example 1 to obtain a polarizing plate with a phase retardation layer.

[0060] (Preparation of the liquid crystal alignment and curing layer constituting the phase retardation layer) 55 parts of the compound represented by formula (I), 25 parts of the compound represented by formula (II), and 20 parts of the compound represented by formula (III) were added to 400 parts of cyclopentanone (CPN). The mixture was heated to 60°C and stirred until dissolved. After confirming dissolution, the mixture was allowed to return to room temperature. Then, 3 parts of Irgacure 907 (manufactured by BASF Japan Co., Ltd.), 0.2 parts of MEGAFAC F-554 (manufactured by DIC Co., Ltd.), and 0.1 parts of 4-methoxyphenol (MEHQ) were added, and the mixture was stirred further to obtain a solution. The solution was transparent and homogeneous. The obtained solution was filtered through a 0.20 μm membrane filter to obtain a polymerizable composition. On the other hand, an alignment film was coated with a polyimide solution onto a 0.7 mm thick glass substrate using spin coating. After drying at 100°C for 10 minutes, it was calcined at 200°C for 60 minutes to obtain a coating film. The obtained coating film was then subjected to a rubbing treatment to form an alignment film. The rubbing treatment was performed using a commercially available rubbing device. The polymeric composition obtained by the above steps was coated onto the substrate (essentially an alignment film) using spin coating and dried at 100°C for 2 minutes. After the obtained coating film was cooled to room temperature, it was irradiated with ultraviolet light at an intensity of 30 mW / cm² using a high-pressure mercury lamp for 30 seconds to obtain a liquid crystal alignment cured layer. The obtained liquid crystal alignment cured layer had an in-plane phase difference Re(550) of 130 nm and a Re(450) / Re(550) of 0.851, exhibiting reverse wavelength dispersion characteristics. Furthermore, the ammonia permeation rate of the obtained liquid crystal alignment and curing layer was 103 g / m2・24h.

[0061] [Chemistry 1][Chemistry 2]

[0062] [Example 7] In the fabrication of the polarizing plate, a TAC film (thickness 25 μm, ammonia permeability 30 g / m2・24h) was used instead of a COP film, and the above-mentioned liquid crystal alignment curing layer was used as the phase retardation layer. When bonding it to the polarizing plate, the above-mentioned adhesive was not used but an ultraviolet curing adhesive (thickness 1.0 μm) was used. Otherwise, it was carried out in the same manner as in Example 1 to obtain a polarizing plate with a phase retardation layer.

[0063] [Comparative Example 1] In the fabrication of the polarizing plate, a 40 μm thick TAC film was used instead of a 25 μm thick TAC film, an acrylic resin film with an lactone ring structure (20 μm thick, ammonia permeability 78 g / m2・24h) was used instead of a COP film, and the above-mentioned liquid crystal alignment curing layer was used as the phase retardation layer. Otherwise, the process was the same as in Example 1 to obtain a polarizing plate with a phase retardation layer.

[0064] [Comparative Example 2] In the fabrication of the polarizing plate, a 40 μm thick TAC film was used instead of a 25 μm thick TAC film, and the above-mentioned liquid crystal alignment curing layer was used as the phase retardation layer. Otherwise, the process was the same as in Example 5, and a polarizing plate with a phase retardation layer was obtained.

[0065] [Comparative Example 3] In the fabrication of the polarizing plate, an acrylic resin film with a lactone ring structure (thickness 20 μm) was used instead of a TAC film with a thickness of 25 μm, an acrylic resin film with a lactone ring structure (thickness 20 μm, ammonia permeability 78 g / m2・24h) was used instead of a COP film, and the above-mentioned liquid crystal alignment and curing layer was used as the phase retardation layer. Otherwise, the process was the same as in Example 1 to obtain a polarizing plate with a phase retardation layer.

[0066] The following evaluation was conducted regarding the embodiments and comparative examples. The evaluation results, along with the composition of the polarizing plate (blocking layer) with the phase retardation layer, are summarized in Table 1. <Evaluation> ○ Single-cell transmittance and polarization Regarding the polarizing plates of the embodiments and comparative examples, the single-cell transmittance Ts, parallel transmittance Tp, and crossed transmittance Tc measured using a UV-Vis spectrophotometer (manufactured by Otsuka Electronics Co., Ltd. "LPF-2000") were used as the Ts, Tp, and Tc of the polarizing element, respectively. These Ts, Tp, and Tc were Y values ​​measured using a 2-degree field of view (C light source) of JIS Z8701 and corrected for visual sensitivity. The polarization P was calculated based on the obtained Tp and Tc using the following formula. Polarization P (%) = {(Tp - Tc) / (Tp + Tc)} 1 / 2 × 100 ○ Ammonia Decolorization Test: 10 g of a 10% ammonia solution was added to a glass bottle (cylindrical shape, 30 mm in diameter and 50 mm in depth). The opening of the glass bottle was covered with a polarizing plate with a phase retardation layer obtained in the examples and comparative examples (the phase retardation layer was in contact with the opening) to seal the bottle. The glass bottle was then heated at 65°C for 2 hours. After heating, the polarization at the location corresponding to the opening of the glass bottle was measured. The polarization of the polarizing plate with the phase retardation layer (essentially a polarizing element) before heating was set as P, and the polarization after heating was set as P'. ΔP was calculated according to the following formula. The smaller ΔP is, the more the ammonia-induced decolorization is suppressed. ΔP = P - P'

[0067] [Table 1] Barrier layer Before the decolorization test After decolorization test ∆P % protective layer Adhesive layer Phase difference layer type Ammonia permeation g / m 2 ・24h Ammonia permeation g / m 2 ・24h type Ammonia permeation g / m 2 ・24h P % P' % Example 1 COP 54 118 membrane 10 99.99 99.94 0.05 Example 2 PET 53 118 membrane 10 99.99 99.93 0.06 Example 3 TAC 30 118 membrane 10 99.99 99.25 1.74 Example 4 acrylic resin 78 118 membrane 10 99.99 99.88 0.11 Example 5 - - 118 membrane 10 99.99 99.92 0.07 Example 6 COP 54 118 liquid crystal 103 99.99 89.57 10.42 Example 7 TAC 30 - liquid crystal 103 99.99 98.28 1.71 Comparative Example 1 acrylic resin 78 118 liquid crystal 103 99.99 65.71 34.28 Comparative Example 2 - - 118 liquid crystal 103 99.99 43.23 56.76 Comparative Example 3 acrylic resin 78 118 liquid crystal 103 99.99 12.39 87.60

[0068] In the embodiments, ΔP is less than 20%, resulting in a polarizing plate with a phase retardation layer that exhibits almost no change in polarization (no decolorization) even when exposed to ammonia. On the other hand, in the comparative examples, the polarization is significantly reduced, even to the point that the polarization function is essentially lost. [Industrial Applicability]

[0069] The polarizing plate with phase difference layer of the present invention can be well used as an anti-reflective circular polarizing plate for, for example, organic EL display devices. [Simplified Explanation of the Diagram]

[0008] FIG1 is a schematic cross-sectional view showing the general configuration of a polarizing plate with a phase retardation layer according to one embodiment of the present invention. FIG2 is a schematic cross-sectional view showing a polarizing plate with a phase retardation layer disposed on an organic EL panel in an organic EL display device according to one embodiment of the present invention.

Claims

1. A polarizing plate with a phase retardation layer, comprising: a polarizing element, and a blocking layer disposed on one side of the polarizing element and including a protective layer and a phase retardation layer, wherein the protective layer is made of a polyester resin, the phase retardation layer is made of a polycarbonate resin, the ammonia permeability of the blocking layer is 70 g / m²·24h or less, and the ammonia permeability of the protective layer is 70 g / m²·24h or less.

2. The polarizing plate with a phase retardation layer as claimed in claim 1, wherein the ammonia permeation of the phase retardation layer is 70 g / m2・24h or less.

3. The polarizing plate with a phase retardation layer as claimed in claim 1 or 2, having a protective layer disposed on the other side of the polarizing element.

4. A polarizing plate with a phase retardation layer as claimed in claim 1 or 2, wherein the transmittance of a single polarizing element is 40% or more and 45% or less.

5. A polarizing plate with a phase retardation layer as requested in item 1 or 2, wherein the Re(450) / Re(550) of the aforementioned phase retardation layer is 0.8 or higher and less than 1.

6. A polarizing plate with a phase retardation layer as claimed in claim 1 or 2, wherein the thickness of the polarizing element is 10 μm or less.

7. The polarizing plate with a phase retardation layer as requested in item 1 or 2 has a thickness of 150 μm or less.

8. An organic electroluminescent display device having a polarizing plate with a phase retardation layer as claimed in any one of claims 1 to 7.

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