Polarizing plate with optical compensation layer and organic el panel using the same

Abstract

The present application provides a polarizing plate with optical compensation layer which has excellent anti-reflection properties in the front direction, excellent anti-reflection properties in the oblique direction, and neutral color in the oblique direction. The polarizing plate with optical compensation layer of the present application is used in an organic EL panel. The polarizing plate with optical compensation layer sequentially comprises a polarizer, a first optical compensation layer, and a second optical compensation layer. The first optical compensation layer exhibits a refractive index characteristic of nx≥nz>ny, and Re(550) is 90 nm to 180 nm. The second optical compensation layer exhibits a refractive index characteristic of nx>ny=nz, and Re(550) is 100 nm to 180 nm. Re(450) and Re(550) of the first optical compensation layer are substantially equal, and the second optical compensation layer satisfies Re(450)>Re(550).

Description

Technical Field

[0001] The present invention relates to a polarizer with an optical compensation layer and an organic EL panel using the polarizer with the optical compensation layer. Background Technology

[0002] In recent years, with the popularization of thin-film displays, displays equipped with organic EL panels (organic EL display devices) have been proposed. Organic EL panels have a highly reflective metal layer, which easily leads to problems such as external light reflection and background reflection. Therefore, it is known to prevent these problems by placing a circular polarizer on the visual confirmation side. As a common circular polarizer, it is known to be obtained by stacking a retardation film (typically a λ / 4 plate) with its slow axis at an angle of approximately 45° relative to the absorption axis of the polarizer. Furthermore, to further improve anti-reflective properties, it has been attempted to stack retardation films (optical compensation layers) with various optical properties. However, existing circular polarizers all suffer from high reflectivity in the tilt direction (i.e., insufficient anti-reflective properties in the tilt direction). In addition, existing circular polarizers also suffer from undesirable coloration in the hue in the tilt direction.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 3325560 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The present invention was made to solve the above-mentioned problems. Its main objective is to provide a polarizer with an optical compensation layer that maintains excellent anti-reflective properties in the front direction while also having excellent anti-reflective properties in the tilt direction and is capable of achieving a neutral hue in the tilt direction for organic EL panels.

[0008] means for solving problems

[0009] The polarizer with optical compensation layer of the present invention can be used in organic EL panels. The polarizer with optical compensation layer sequentially comprises a polarizer, a first optical compensation layer, and a second optical compensation layer. The first optical compensation layer exhibits refractive index characteristics of nx ≥ nz > ny, with Re(550) of 90 nm to 180 nm and Nz coefficient of 0 to 0.8. The absorption axis direction of the polarizer is substantially parallel to the slow axis direction of the first optical compensation layer, and Re(450) and Re(550) of the first optical compensation layer are substantially equal. The second optical compensation layer exhibits refractive index characteristics of nx > ny = nz, with Re(550) of 100 nm to 180 nm. The absorption axis direction of the polarizer is 35° to 55° to the slow axis direction of the second optical compensation layer, and Re(550) > Re(450) of the second optical compensation layer. Here, Re(450) and Re(550) represent the in-plane phase differences measured with light at 23°C and wavelengths of 450 nm and 550 nm, respectively.

[0010] In one embodiment, the first optical compensation layer exhibits refractive index characteristics of nx > nz > ny, with Re(550) ranging from 90 nm to 170 nm and an Nz coefficient ranging from 0.1 to 0.5. The angle between the absorption axis of the polarizer and the slow axis of the first optical compensation layer is 5° to 25°, and Re(450) and Re(550) of the first optical compensation layer are substantially equal. The second optical compensation layer exhibits refractive index characteristics of nx > ny = nz, with Re(550) ranging from 60 nm to 140 nm. The angle between the slow axis of the first optical compensation layer and the slow axis of the second optical compensation layer is 50° to 70°, and the second optical compensation layer satisfies Re(550) > Re(450). Here, Re(450) and Re(550) represent the in-plane phase difference measured with light at 23°C with wavelengths of 450 nm and 550 nm, respectively.

[0011] According to other aspects of the invention, an organic EL panel is provided. This organic EL panel includes the aforementioned polarizer with an optical compensation layer.

[0012] Invention Effects

[0013] According to the present invention, in a polarizer with an optical compensation layer, a first optical compensation layer and a second optical compensation layer are sequentially arranged from the polarizer side. The first optical compensation layer exhibits refractive index characteristics of nx > nz > ny or nx = nz > ny, has a specified in-plane phase difference, and exhibits flat dispersion characteristics. The second optical compensation layer exhibits refractive index characteristics of nx > ny = nz, has a specified in-plane phase difference, and satisfies Re(550) > Re(450). Thus, a polarizer with an optical compensation layer can be obtained that maintains excellent anti-reflective characteristics in the front direction while also exhibiting excellent anti-reflective characteristics in the tilt direction and having a neutral hue in the tilt direction. Attached Figure Description

[0014] Figure 1 This is a cross-sectional schematic diagram of a polarizer with an optical compensation layer according to one embodiment of the present invention.

[0015] Symbol Explanation

[0016] 10 polarizers

[0017] 20 protective layers

[0018] 30 First optical compensation layer

[0019] 40 Second optical compensation layer

[0020] 100 Polarizers with Optical Compensation Layers Detailed Implementation

[0021] The preferred embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

[0022] (Definitions of terms and symbols)

[0023] The definitions of terms and symbols used in this specification are as follows.

[0024] (1) Refractive index (nx, ny, nz)

[0025] “nx” is the refractive index in the direction of maximum refractive index within the plane (i.e., the slow axis direction), “ny” is the refractive index in the direction orthogonal to the slow axis within the plane (i.e., the fast axis direction), and “nz” is the refractive index in the thickness direction.

[0026] (2) In-plane phase difference (Re)

[0027] “Re(λ)” is the in-plane phase difference measured with light at 23°C and a wavelength of λnm. Re(λ) is calculated using the formula: Re = (nx - ny) × d when the thickness of the layer (film) is set to d (nm). For example, “Re(550)” is the in-plane phase difference measured with light at 23°C and a wavelength of 550nm.

[0028] (3) Phase difference (Rth) in the thickness direction

[0029] “Rth(λ)” is the phase difference in the thickness direction measured with light at 23°C and a wavelength of λnm. Rth(λ) is calculated using the formula: Rth=(nx-nz)×d when the thickness of the layer (film) is set to d (nm). For example, “Rth(550)” is the phase difference in the thickness direction measured with light at 23°C and a wavelength of 550nm.

[0030] (4) Nz coefficient

[0031] The Nz coefficient is obtained from Nz = Rth / Re.

[0032] (5) In fact, they are orthogonal or parallel

[0033] The expressions "substantially orthogonal" and "approximately orthogonal" include cases where the angle between the two directions is 90° ± 10°, preferably 90° ± 7°, and more preferably 90° ± 5°. The expressions "substantially parallel" and "approximately parallel" include cases where the angle between the two directions is 0° ± 10°, preferably 0° ± 7°, and more preferably 0° ± 5°. Furthermore, in this specification, the use of "orthogonal" or "parallel" can include states that are substantially orthogonal or substantially parallel.

[0034] A. Overall structure of a polarizer with optical compensation layer

[0035] Figure 1This is a cross-sectional schematic diagram of a polarizer with an optical compensation layer according to one embodiment of the present invention. The polarizer 100 with an optical compensation layer of this embodiment sequentially includes a polarizer 10, a first optical compensation layer 30, and a second optical compensation layer 40. In practical terms, a protective layer 20 can be provided on the side of the polarizer 10 opposite to the first optical compensation layer 30, as shown in the example. Alternatively, the polarizer with the optical compensation layer may have another protective layer (also called an inner protective layer) between the polarizer 10 and the first optical compensation layer 30. In the example, the inner protective layer is omitted. In this case, the first optical compensation layer 30 can also function as an inner protective layer. Furthermore, as needed, a conductive layer and a substrate (neither shown) can be sequentially provided on the side of the second optical compensation layer 40 opposite to the first optical compensation layer 30 (i.e., the outer side of the second optical compensation layer 40). The substrate and the conductive layer are tightly laminated. In this specification, "tightly laminated" means that two layers are directly and firmly laminated without being separated by an adhesive layer (e.g., an adhesive layer, bonding agent layer). The conductive layer and substrate can typically be incorporated into the polarizer 100 with an optical compensation layer in the form of a laminate of the substrate and the conductive layer. By further providing the conductive layer and substrate, the polarizer 100 with an optical compensation layer can be applied to an internal touch panel type input display device. Furthermore / or, as needed, the polarizer with an optical compensation layer (essentially the protective layer 20) can be treated to improve visual clarity when visually inspected through polarized sunglasses (typically by imparting (ellipsoidal) polarization or providing an ultra-high phase difference). By implementing such treatment, excellent visual clarity can be achieved even when visually inspecting the display image through polarized lenses such as polarized sunglasses. Therefore, the polarizer with an optical compensation layer can also be applied to image display devices that can be used outdoors.

[0036] In one embodiment, the refractive index characteristics of the first optical compensation layer 30 exhibit a relationship of nx ≥ nz > ny and have a slow axis. The in-plane phase difference Re(550) of the first optical compensation layer 30 is 90 nm to 180 nm. In this case, the Nz coefficient of the first optical compensation layer is 0 to 0.8, the angle between the slow axis of the first optical compensation layer 30 and the absorption axis of the polarizer 10 is substantially parallel, and the Re(450) and Re(550) of the first optical compensation layer are substantially equal. That is, it has a flat dispersion characteristic in which the phase difference value hardly changes with the wavelength of the measured light. Furthermore, the refractive index characteristics of the second optical compensation layer 40 exhibit a relationship of nx > ny = nz and have a slow axis. The in-plane phase difference Re(550) of the second optical compensation layer 40 is 100 nm to 180 nm. In this case, the angle between the slow axis of the second optical compensation layer 30 and the absorption axis of the polarizer 10 is 35° to 55°, preferably 38° to 52°, more preferably 42° to 48°, and even more preferably about 45°. Furthermore, the second optical compensation layer satisfies Re(550) > Re(450). That is, it has a reverse dispersion characteristic where the phase difference increases with the wavelength of the measured light. In another embodiment, the refractive index characteristics of the first optical compensation layer 30 exhibit a relationship of nx > nz > ny and have a slow axis. The in-plane phase difference Re(550) of the first optical compensation layer 30 is preferably 90 nm to 170 nm. In this case, the Nz coefficient of the first optical compensation layer is preferably 0.1 to 0.5, and the angle between the slow axis of the first optical compensation layer 30 and the absorption axis of the polarizer 10 is preferably 5° to 25°, more preferably 8° to 22°, even more preferably 10° to 20°, and particularly preferably about 13°. Furthermore, regarding the second optical compensation layer 40, its refractive index characteristics exhibit a relationship of nx > ny = nz and it has a slow axis. The in-plane phase difference Re(550) of the second optical compensation layer 40 is 60 nm to 140 nm. In this case, the angle between the slow axis of the second optical compensation layer 30 and the absorption axis of the polarizer 10 is preferably 50° to 70°, more preferably 53° to 67°, even more preferably 55° to 65°, and particularly preferably about 58°. By sequentially arranging the first optical compensation layer, which exhibits the above-mentioned refractive index characteristics, has a predetermined in-plane phase difference, and exhibits flat dispersion characteristics, and the second optical compensation layer, which exhibits the above-mentioned refractive index characteristics, has a predetermined in-plane phase difference, and exhibits anti-dispersion characteristics, from the polarizer side, the excellent anti-reflection characteristics in the front direction due to the excellent circular polarization function can be maintained, and light leakage caused by apparent axial offset of the absorption axis of the polarizer when viewed from an oblique direction can be prevented. As a result, when a polarizer with an optical compensation layer is applied to an organic EL panel, excellent anti-reflective properties can be achieved in the tilt direction, thereby achieving a neutral (i.e., no undesirable hue) in the tilt direction.

[0037] The following is a detailed description of each layer and optical film that constitute the polarizer with the optical compensation layer.

[0038] A-1. Polarizer

[0039] As the polarizer 10, any suitable polarizer can be used. For example, the resin film forming the polarizer can be a single-layer resin film or a laminate of two or more layers.

[0040] Specific examples of polarizers composed of single-layer resin films include: polarizers obtained by dyeing and stretching hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene-vinyl acetate copolymer films using dichroic substances such as iodine and dichroic dyes; and polyene-based oriented films such as dehydrated PVA products and dehydrochlorinated polyvinyl chloride products. From the perspective of superior optical properties, polarizers obtained by dyeing PVA films with iodine and then uniaxially stretching them are preferred.

[0041] The dyeing process using iodine described above is performed, for example, by immersing the PVA membrane in an aqueous iodine solution. The stretching ratio for the uniaxial stretching is preferably 3 to 7 times. Stretching can be performed after dyeing or simultaneously with dyeing. Alternatively, dyeing can be performed after stretching. The PVA membrane can be subjected to swelling treatment, cross-linking treatment, cleaning treatment, drying treatment, etc., as needed. For example, by immersing the PVA membrane in water for washing before dyeing, not only can stains and anti-blocking agents on the surface of the PVA membrane be washed away, but the PVA membrane can also swell to prevent uneven dyeing.

[0042] Specific examples of polarizers obtained using laminates include: polarizers obtained using a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and a PVA-based resin layer coated on the resin substrate. A polarizer obtained using a resin substrate and a PVA-based resin layer coated on the resin substrate can be manufactured, for example, by coating a PVA-based resin solution onto a resin substrate and drying it to form a PVA-based resin layer on the resin substrate, thereby obtaining a laminate of the resin substrate and the PVA-based resin layer; stretching and dyeing the laminate to form a polarizer from the PVA-based resin layer. In this embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution for stretching. Furthermore, stretching may, as needed, further include air stretching of the laminate at a high temperature (e.g., above 95°C) prior to stretching in the aqueous boric acid solution. The resulting resin substrate / polarizer laminate can be used directly (i.e., the resin substrate can be used as a protective layer for the polarizer), or the resin substrate can be peeled off from the resin substrate / polarizer laminate and any suitable protective layer corresponding to the purpose can be laminated on the peeled surface for use. Detailed description of such a polarizer manufacturing method is disclosed, for example, in Japanese Patent Application Publication No. 2012-73580 (Japanese Patent No. 5414738). The entire contents of that publication are incorporated herein by reference.

[0043] The thickness of the polarizer is preferably 25 μm or less, more preferably 1 μm to 12 μm, even more preferably 3 μm to 12 μm, and particularly preferably 3 μm to 8 μm. As long as the thickness of the polarizer is within this range, curling during heating can be well suppressed, and good appearance durability during heating can be obtained.

[0044] The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The transmittance of the polarizer is preferably 42.0% to 46.0%, more preferably 44.5% to 46.0%. The polarization degree of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

[0045] A-2. First optical compensation layer

[0046] Regarding the first optical compensation layer 30, its refractive index characteristics exhibit a relationship of nx > nz > ny or nx = nz > ny and it has a slow axis. Furthermore, the first optical compensation layer 30 exhibits a flat wavelength dispersion characteristic in which the phase difference value hardly changes with the wavelength of the measured light. Specifically, the Re(450) / Re(550) of the first optical compensation layer is preferably 0.99 to 1.03.

[0047] In one embodiment, the refractive index characteristics of the first optical compensation layer 30 exhibit a relationship of nx ≥ nz > ny, and the in-plane phase difference Re(550) is 90 nm to 180 nm. As long as the in-plane phase difference of the first optical compensation layer is within such a range, by making the slow axis direction of the first optical compensation layer substantially parallel to the absorption axis direction of the polarizer, it is possible to prevent a reduction in anti-reflection performance in the tilt direction caused by an apparent axial offset of the absorption axis of the polarizer. Furthermore, in this case, in one embodiment, the Nz coefficient of the first optical compensation layer is 0 to 0.8. As long as the Nz coefficient is within such a range, by adjusting the angle between the slow axis of the first optical compensation layer and the absorption axis of the polarizer to a predetermined angle, superior anti-reflection characteristics in the tilt direction can be achieved.

[0048] In another embodiment, the refractive index characteristics of the first optical compensation layer 30 exhibit a relationship of nx > nz > ny, and the in-plane phase difference Re(550) is preferably 90 nm to 170 nm, more preferably 100 nm to 160 nm, and even more preferably 120 nm to 140 nm. As long as the in-plane phase difference of the first optical compensation layer is within such a range, by setting the slow axis direction of the first optical compensation layer at an angle of 5° to 25° (particularly about 13°) relative to the absorption axis direction of the polarizer as described above, it is possible to prevent a reduction in the anti-reflection function in the tilt direction caused by the apparent axial offset of the absorption axis of the polarizer. Furthermore, in this case, the Nz coefficient of the first optical compensation layer is preferably 0.1 to 0.5, more preferably 0.15 to 0.45, and even more preferably 0.2 to 0.4. As long as the Nz coefficient is within such a range, by adjusting the angle between the slow axis of the first optical compensation layer and the absorption axis of the polarizer to a predetermined angle, superior anti-reflection characteristics in the tilt direction can be achieved.

[0049] The first optical compensation layer is typically formed of a resin film, which is formed of any suitable resin capable of achieving the aforementioned properties. Examples of resins used to form this resin film include: polycarbonate resins, cyclic olefin resins, cellulose resins, polyester resins, polyvinyl alcohol resins, polyamide resins, polyimide resins, polyether resins, polystyrene resins, acrylic resins, and polyester carbonate resins. Among these, cyclic olefin resins or polycarbonate resins may be suitably used.

[0050] Cyclic olefin resins are a general term for resins polymerized using cyclic olefins as polymerizing units. Examples include resins described in Japanese Patent Application Publication Nos. 1-240517, 3-14882, and 3-122137. Specific examples include: ring-opening (copolymer) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins with α-olefins such as ethylene and propylene (typically random copolymers), and graft-modified products obtained by modifying them with unsaturated carboxylic acids and their derivatives, as well as their hydrides. Specific examples of cyclic olefins include norbornene monomers. Norbornene monomers include monomers described in Japanese Patent Application Publication No. 2015-210459, etc. Various commercially available products are made from the aforementioned cyclic olefin resins. Specific examples include: products manufactured by ZEON Corporation of Japan under the names "ZEONEX" and "ZEONOR", products manufactured by JSR Corporation under the name "Arton", products manufactured by TICNA Corporation under the name "TOPAS", and products manufactured by Mitsui Chemicals Corporation under the name "APEL".

[0051] As a polycarbonate resin, any suitable polycarbonate resin can be used as long as the effects of the present invention are achieved. Preferably, the polycarbonate resin comprises structural units derived from isosorbide-based dihydroxy compounds and structural units derived from at least one dihydroxy compound selected from alicyclic diols, alicyclic diethanols, diethylene glycol, triethylene glycol, or polyethylene glycol, and alkylene glycols or spirodiols. More preferably, the polycarbonate resin comprises structural units derived from isosorbide-based dihydroxy compounds, structural units derived from alicyclic diethanols, and / or structural units derived from diethylene glycol, triethylene glycol, or polyethylene glycol. The polycarbonate resin may, as needed, comprise structural units derived from other dihydroxy compounds. Furthermore, details of the polycarbonate resin and the method for manufacturing the retardation film suitable for use in the present invention are described, for example, in International Publication No. 2011 / 062239, which is incorporated herein by reference.

[0052] The first optical compensation layer can be formed, for example, by coating a coating liquid, in which the aforementioned resin is dissolved or dispersed in any suitable solvent, onto a shrinkable film to form a coating film, and then shrinking the coating film. Typically, regarding the shrinkage of the coating film, the shrinkable film is shrunk by heating the laminate of the shrinkable film and the coating film, thereby shrinking the coating film. The shrinkage rate of the coating film is preferably 0.50 to 0.99, more preferably 0.60 to 0.98, and even more preferably 0.70 to 0.95. The heating temperature is preferably 130°C to 170°C, more preferably 150°C to 160°C. In one embodiment, when shrinking the coating film, the laminate can be stretched along a direction orthogonal to the shrinkage direction. In this case, the stretching ratio of the laminate is preferably 1.01 to 3.0 times, more preferably 1.05 to 2.0 times, and even more preferably 1.10 to 1.50 times. Specific examples of materials constituting a shrinkable film include: polyolefins, polyesters, acrylic resins, polyamides, polycarbonates, norbornene resins, polystyrene, polyvinyl chloride, polyvinylidene chloride, cellulose resins, polyethersulfone, polysulfone, polyimide, polyacrylic acid, acetate resins, polyarylates, polyvinyl alcohol, and liquid crystal polymers. These can be used individually or in combination. A stretchable film formed from these materials is preferred.

[0053] The thickness of the first optical compensation layer is preferably 10 μm to 150 μm, more preferably 10 μm to 100 μm, and even more preferably 10 μm to 30 μm. With such a thickness, the desired in-plane phase difference and Nz coefficient can be obtained.

[0054] A-3. Second optical compensation layer

[0055] Regarding the second optical compensation layer 40, its refractive index characteristics exhibit a relationship of nx > ny = nz and it has a slow axis. Furthermore, the second optical compensation layer exhibits a back-dispersion wavelength characteristic where the phase difference increases with the wavelength of the measured light. That is, it satisfies Re(550) > Re(450). By satisfying this relationship, excellent reflectance hue can be achieved.

[0056] The in-plane phase difference Re(550) of the second optical compensation layer 40 is 100nm to 180nm, preferably 110nm to 170nm, and more preferably 130nm to 150nm. As long as the in-plane phase difference of the second optical compensation layer is within such a range, excellent anti-reflection characteristics can be achieved by setting the slow axis direction of the second optical compensation layer at an angle of 35° to 55° (especially about 45°) relative to the absorption axis direction of the polarizer, as described above.

[0057] In another embodiment, as described above, the refractive index characteristics of the second optical compensation layer 40 exhibit a relationship of nx > ny = nz. The in-plane phase difference Re(550) of the second optical compensation layer is preferably 90 nm to 170 nm, more preferably 90 nm to 120 nm, and even more preferably 90 nm to 100 nm. As long as the in-plane phase difference of the second optical compensation layer is within such a range, excellent anti-reflection characteristics can be achieved by setting the slow axis direction of the second optical compensation layer at an angle of preferably 50° to 70° (particularly preferably about 58°) relative to the absorption axis direction of the polarizer, as described above.

[0058] The second optical compensation layer is typically a retardation film formed from any suitable resin capable of achieving the above-described properties. Polycarbonate resin is preferably used as the resin for forming this retardation film.

[0059] As the aforementioned polycarbonate resin, any suitable polycarbonate resin can be used as long as the effects of the present invention are achieved. Preferably, the polycarbonate resin comprises 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 alicyclic diols, alicyclic diethanols, diethylene glycol, triethylene glycol, or polyethylene glycol, and alkylene glycols or spirodiols. More 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 diethanols, and / or structural units derived from diethylene glycol, triethylene glycol, 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 diethylene glycol, triethylene glycol, or polyethylene glycol. The polycarbonate resin may, as needed, comprise structural units derived from other dihydroxy compounds. Furthermore, details of the polycarbonate resins that may be suitably used in this invention are described, for example, in Japanese Patent Application Publication No. 2014-10291 and Japanese Patent Application Publication No. 2014-26266 (Japanese Patent No. 5528606), which are incorporated herein by reference.

[0060] The retardation film (i.e., the second optical compensation layer) is typically made by stretching a resin film along at least one direction.

[0061] Any suitable method can be used as the method for forming the aforementioned resin film. For example, the following methods can be listed: melt extrusion (e.g., T-die forming), casting coating (e.g., casting), calendering, hot pressing, co-extrusion, co-melting, multilayer extrusion, blow molding, etc. T-die forming, casting, and blow molding are preferred.

[0062] The thickness of the resin film (unstretched film) is set to any appropriate value based on the desired optical properties and the stretching conditions described later. Preferably, it is 50 μm to 300 μm.

[0063] The stretching described above can be performed using any appropriate stretching method and conditions (e.g., stretching temperature, stretching ratio, stretching direction). Specifically, various stretching methods such as free-end stretching, fixed-end stretching, free-end shrinkage, and fixed-end shrinkage can be used individually, or these methods can be used simultaneously or sequentially. The stretching direction can also be in various directions and dimensions, such as horizontal, vertical, thickness, and diagonal. The stretching temperature relative to the glass transition temperature (Tg) of the resin film is preferably Tg-30℃ to Tg+60℃, more preferably Tg-10℃ to Tg+50℃.

[0064] By appropriately selecting the stretching method and stretching conditions described above, a phase difference film (i.e., the second optical compensation layer) with the desired optical properties (e.g., refractive index characteristics, in-plane phase difference, Nz coefficient) can be obtained.

[0065] The thickness of the phase retardation film (stretched film, i.e., the second optical compensation layer) is preferably 20 μm to 100 μm, more preferably 20 μm to 80 μm, and even more preferably 20 μm to 65 μm. With such a thickness, the desired in-plane phase difference and thickness direction phase difference can be obtained.

[0066] By combining the first optical compensation layer described in A-2. with the second optical compensation layer described in A-3., a polarizer with an optical compensation layer can be obtained that maintains excellent anti-reflective properties in the front direction while also exhibiting excellent anti-reflective properties in the tilt direction, thereby enabling an organic EL panel with a neutral hue in the tilt direction.

[0067] A-4. Protective Layer

[0068] The protective layer 20 is formed of any suitable film that can be used as a protective layer for a polarizer. Specific examples of materials that are the main components of this film include: cellulose resins such as cellulose triacetate (TAC), polyester resins, polyvinyl alcohol resins, polycarbonate resins, polyamide resins, polyimide resins, polyethersulfone resins, polysulfone resins, polystyrene resins, polynorbornene resins, polyolefin resins, (meth)acrylic acid resins, acetate resins, and other transparent resins. Additionally, thermosetting or UV-curing resins such as (meth)acrylic acid resins, urethane resins, (meth)acrylate urethane resins, epoxy resins, and silicone resins can also be used. Furthermore, glassy polymers such as siloxane polymers can also be used. Additionally, the polymer film described in Japanese Patent Application Publication No. 2001-343529 (WO01 / 37007) can also be used. As the material for this membrane, for example, a resin composition containing a thermoplastic resin having substituted or unsubstituted imide groups on the side chains and a thermoplastic resin having substituted or unsubstituted phenyl and nitrile groups on the side chains can be used. Examples include resin compositions having alternating copolymers formed from isobutylene and N-methylmaleimide and acrylonitrile-styrene copolymers. The polymer membrane can be, for example, an extruded product of the above-mentioned resin composition.

[0069] As needed, the protective layer 20 can be subjected to surface treatments such as hard coating, anti-reflective treatment, anti-sticking treatment, and anti-glare treatment.

[0070] The thickness of the protective layer 20 is typically 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and even more preferably 5 μm to 150 μm. Furthermore, when a surface treatment has been performed, the thickness of the protective layer includes the thickness of the surface treatment layer.

[0071] When an inner protective layer is provided between the polarizer 10 and the first optical compensation layer 30, the inner protective layer 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. As long as the inner protective layer is optically isotropic, it can be made of any suitable material. For example, the material can be appropriately selected from the materials described above for the protective layer 20.

[0072] The thickness of the inner protective layer is preferably 5μm to 200μm, more preferably 10μm to 100μm, and even more preferably 15μm to 95μm.

[0073] A-5. Other

[0074] The layers constituting the polarizer with optical compensation layer are bonded together with any suitable adhesive layer or bonding agent layer.

[0075] Although not shown, an adhesive layer can also be provided on the side of the second optical compensation layer 40 of the polarizer 100 with the optical compensation layer. By pre-providing the adhesive layer, it can be easily bonded to other optical components (e.g., organic EL panels). Furthermore, it is preferable to attach a release film to the surface of the adhesive layer until it is ready for use. By temporarily attaching the release film, the adhesive layer can be protected and a roll can be formed.

[0076] B. Organic EL Panel

[0077] The organic EL panel of the present invention includes an organic EL unit and a polarizer with an optical compensation layer as described in item A above, disposed on the visual confirmation side of the organic EL unit. The polarizer with the optical compensation layer is stacked such that the second optical compensation layer is on the organic EL unit side (the polarizer is on the visual confirmation side).

[0078] Example

[0079] The present invention will be specifically described below through examples, but the present invention is not limited to these examples. Furthermore, the methods for measuring each characteristic are described below.

[0080] (1) Thickness

[0081] The measurements were performed using a dial indicator (manufactured by PEACOCK, product name "DG-205") and a dial indicator stand (product name "pds-2").

[0082] (2) Phase difference

[0083] A 50mm × 50mm sample was cut from the phase retardation film of the optical compensation layer of each polarizer constituting the embodiments and comparative examples as a measurement sample, and measurements were performed using an Axoscan manufactured by Axometrics. The measurement wavelengths were 450nm and 550nm, and the measurement temperature was 23°C.

[0084] In addition, the average refractive index was measured using an Abbe refractometer manufactured by Atago, and the refractive indices nx, ny, and nz were calculated from the obtained phase difference values.

[0085] (3) Frontal reflectance brightness

[0086] An organic EL display device was obtained by bonding a polarizer with an optical compensation layer, obtained from the examples and comparative examples, to the visual confirmation side of the organic EL panel of an organic EL display device (LG Display, product name "55C7P") through an adhesive layer so that the optical compensation layer is on the organic EL side.

[0087] The organic EL was made to display a black image, and the frontal reflectance was measured using a spectrophotometer (product name "CM-2600D") manufactured by Konica Minolta.

[0088] (4) Reflection characteristics in the tilt direction

[0089] The characteristics of the polarizer with optical compensation layer obtained from the examples and comparative examples were simulated. The tilt direction (polar angle 60°) was evaluated. Shintech's "LCD MASTER Ver. 6.084" was used in the simulation. The reflection characteristics were simulated using the extended functions of LCD Master.

[0090] [Example 1]

[0091] (i) Fabrication of the first optical compensation layer

[0092] A commercially available cyclic olefin resin film (manufactured by JSR Corporation, product name "Arton(R5000)") was used as the resin film. The thickness was 130 μm, and the Tg was 137 °C. A 60 μm thick shrinkable film (manufactured by Toray Industries, product name "TORAYFAN BO2873") was laminated to both sides of the film through an acrylic adhesive layer (15 μm thick), and then unidirectionally stretched at the free end to obtain the phase retardation film constituting the first optical compensation layer. The stretching temperature was set to 165 °C, and the stretching ratio was set to 1.14 times. The resulting first optical compensation layer had a Re(550) of 101 nm and an Nz coefficient of 0. The Re(450) / Re(550) ratio was 1.00.

[0093] (ii) Fabrication of the second optical compensation layer

[0094] (ii-1) Fabrication of polycarbonate resin film

[0095] Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with agitators and reflux coolers controlled at 100°C. The molar ratios of 9,9-[4-(2-hydroxyethoxy)phenyl]fluorene (BHEPF), isosorbide (ISB), diethylene glycol (DEG), diphenyl carbonate (DPC), and magnesium acetate tetrahydrate were BHEPF / ISB / DEG / DPC / magnesium acetate = 0.348 / 0.490 / 0.162 / 1.005 / 1.00 × 10⁻⁶. -5The reactor was fed in the following manner: Nitrogen replacement was performed thoroughly (oxygen concentration 0.0005–0.001 vol%), followed by heating with a heat medium. Stirring was initiated when the internal temperature reached 100°C. After 40 minutes of initial heating, the internal temperature was raised to 220°C and maintained at this temperature. Simultaneously, pressure was reduced, and after reaching 220°C, a pressure of 13.3 kPa was applied for 90 minutes. Phenol vapor, a byproduct of the polymerization reaction, was introduced into a 100°C reflux cooler to return the small amount of monomer components contained in the phenol vapor to the reactor. Uncondensed phenol vapor was recovered by introducing it into a 45°C condenser.

[0096] Nitrogen was introduced into the first reactor to temporarily restore it to atmospheric pressure, and then the oligomerized reaction liquid in the first reactor was transferred to the second reactor. Next, heating and depressurization were initiated in the second reactor, setting the internal temperature to 240°C and the pressure to 0.2 kPa for 50 minutes. Polymerization was then carried out until the specified stirring motive force was reached. At the moment the specified motive force was reached, nitrogen was introduced into the reactor to restore the pressure, and the reaction liquid was extracted in the form of a filament. Granulation was performed using a rotary cutter to obtain a polycarbonate resin with a copolymer composition of BHEPF / ISB / DEG = 34.8 / 49.0 / 16.2 [mol%). This polycarbonate resin has a specific viscosity of 0.430 dL / g and a glass transition temperature of 128°C.

[0097] (ii-2) Fabrication of the second optical compensation layer

[0098] The obtained polycarbonate resin was vacuum dried at 80°C for 5 hours. Then, a film-forming device equipped with a single-screw extruder (manufactured by Isuzu Chemical Machinery Co., Ltd., screw diameter 25 mm, cylinder set temperature: 220°C), a T-die (width 900 mm, set temperature: 220°C), a cooling roller (set temperature: 125°C), and a winding machine was used to produce a polycarbonate resin film with a thickness of 130 μm. The water absorption rate of the obtained polycarbonate resin film was 1.2%.

[0099] A phase retardation film constituting the second optical compensation layer was obtained by oblique stretching of the polycarbonate resin film obtained as described above, according to the method of Example 1 of Japanese Patent Application Publication No. 2014-194483. The obtained phase retardation film (i.e., the second optical compensation layer) has a Re(550) of 137 nm, an Nz coefficient of 1.0, and a Re(450) / Re(550) ratio of 0.89.

[0100] (iii) Fabrication of the polarizer

[0101] While stretching a 30μm thick polyvinyl alcohol (PVA) resin film (manufactured by Toray, product name "PE3000") unidirectionally to 5.9 times its original thickness using a roller stretching machine, swelling, dyeing, crosslinking, and cleaning processes are simultaneously carried out, and finally drying is performed, thus producing a polarizer with a thickness of 12μm.

[0102] Specifically, for the swelling treatment, the particle size was stretched to 2.2 times while being treated with pure water at 20°C. Next, for the dyeing treatment, the particle size was stretched to 1.4 times while being treated in an aqueous solution at 30°C with an iodine to potassium iodide weight ratio of 1:7, adjusted to achieve a monomer transmittance of 45.0% for the resulting polarizer. Furthermore, the crosslinking treatment employed a two-stage process. In the first stage, the particle size was stretched to 1.2 times while being treated in an aqueous solution containing boric acid and potassium iodide at 40°C. The boric acid content in the first stage crosslinking treatment aqueous solution was set to 5.0% by weight, and the potassium iodide content was set to 3.0% by weight. In the second stage, the particle size was stretched to 1.6 times while being treated in an aqueous solution containing boric acid and potassium iodide at 65°C. The boric acid content in the second stage crosslinking treatment aqueous solution was set to 4.3% by weight, and the potassium iodide content was set to 5.0% by weight. Finally, the cleaning treatment was performed in an aqueous solution of potassium iodide at 20°C. The potassium iodide content of the aqueous solution used for cleaning was set at 2.6% by weight. Finally, the polarizer was obtained by drying at 70°C for 5 minutes.

[0103] (iv) Fabrication of polarizers

[0104] By bonding an HC-TAC film (thickness: 32μm, corresponding to the protective layer) with a hard coating (HC) layer (7μm) formed on one side of the TAC film (25μm) through a polyvinyl alcohol adhesive, a strip-shaped polarizer with a protective layer / polarizer structure is obtained.

[0105] (v) Fabrication of a polarizer with an optical compensation layer

[0106] By rolling together the polarizer described in (iv), the phase retardation film (first optical compensation layer) described in (i), and the phase retardation film (second optical compensation layer) described in (ii), a phase retardation film laminate is obtained. The shrinkage film is then peeled off to obtain a polarizer with an optical compensation layer, comprising a protective layer / polarizer / first optical compensation layer / second optical compensation layer. The absorption axis of the polarizer is substantially parallel to the slow axis of the first optical compensation layer, and the angle between the absorption axis of the polarizer and the slow axis of the second optical compensation layer is 45°.

[0107] The obtained polarizer with optical compensation layer was used for the evaluation described in (3) above. Furthermore, the reflection characteristics described in (4) above were simulated using the properties of the obtained polarizer with optical compensation layer. The results are shown in Table 1.

[0108] [Example 2]

[0109] Except for the stretching temperature and stretching ratio described in Table 1, a polarizer with an optical compensation layer, consisting of a protective layer / polarizer / first optical compensation layer / second optical compensation layer, was obtained in the same manner as in Example 1. The first optical compensation layer has a Re(550) of 138 nm, an Nz coefficient of 0.5, and a Re(450) / Re(550) ratio of 1.00. The second optical compensation layer has a Re(550) of 137 nm, an Nz coefficient of 1.0, and a Re(450) / Re(550) ratio of 0.89. Furthermore, an organic EL panel was fabricated in the same manner as in Example 1, except that this polarizer with an optical compensation layer was used. The obtained polarizer with an optical compensation layer was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0110] [Example 3]

[0111] Except for the stretching temperature and stretching ratio described in Table 1, a polarizer with an optical compensation layer, consisting of a protective layer / polarizer / first optical compensation layer / second optical compensation layer, was obtained in the same manner as in Example 1. The first optical compensation layer has a Re(550) of 173 nm, an Nz coefficient of 0.64, and a Re(450) / Re(550) ratio of 1.00. The second optical compensation layer has a Re(550) of 137 nm, an Nz coefficient of 1.0, and a Re(450) / Re(550) ratio of 0.89. Furthermore, except for the use of this polarizer with an optical compensation layer, an organic EL panel was fabricated in the same manner as in Example 1. The obtained polarizer with an optical compensation layer and organic EL panel were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0112] [Example 4]

[0113] The stretching temperature and stretching ratio described in Table 1 were used. The first optical compensation layer and the second optical compensation layer were bonded together roll-to-roll to obtain a laminate with the first optical compensation layer / second optical compensation layer configuration. The angle between the slow axis of the first optical compensation layer and the slow axis of the second optical compensation layer was 45°. The laminate was cut to a specified size, and the polarizer was further cut and bonded with the angle between the absorption axis of the polarizer and the slow axis of the first optical compensation layer being 13° and the angle between the absorption axis of the polarizer and the slow axis of the second optical compensation layer being 58°, resulting in a polarizer with an optical compensation layer configuration consisting of a protective layer / polarizer / first optical compensation layer / second optical compensation layer. The number of times the process (RtoS) of cutting and bonding each layer constituting the polarizer with the optical compensation layer was performed was one. The Re(550) of the first optical compensation layer was 133 nm, the Nz coefficient was 0.27, and the Re(450) / Re(550) ratio was 1.00. The second optical compensation layer has a Re(550) of 98 nm, an Nz coefficient of 1.0, and a Re(450) / Re(550) ratio of 0.89. Furthermore, except for the use of this polarizer with the optical compensation layer, an organic EL panel was fabricated in the same manner as in Example 1. The obtained polarizer with the optical compensation layer and the organic EL panel were subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0114] [Comparative Example 1]

[0115] (i) Fabrication of the first optical compensation layer

[0116] The first optical compensation layer was fabricated in the same manner as the second optical compensation layer in Example 1. The first optical compensation layer has a Re(550) of 139 nm, an Nz coefficient of 1.10, and a Re(450) / Re(550) ratio of 0.89.

[0117] (ii) Fabrication of the second optical compensation layer

[0118] A liquid crystal coating solution was prepared by dissolving 20 parts by weight of a side-chain liquid crystal polymer represented by the following chemical formula (II) (where the numbers 65 and 35 represent the molar percentage of monomer units; for convenience, it is represented as a block polymer; the weight-average molecular weight is 5000), 80 parts by weight of a polymerizable liquid crystal displaying a nematic liquid crystal phase (manufactured by BASF: product name Paliocolor LC242), and 5 parts by weight of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: product name IRGACURE 907) in 200 parts by weight of cyclopentanone. The coating solution was then applied to a substrate film (norbornene resin film: manufactured by ZEON Corporation, Japan, product name "ZEONEX") using a wire-bar coater, and then heated and dried at 80°C for 4 minutes to orient the liquid crystal. The liquid crystal layer was cured by irradiating it with ultraviolet light, forming a cured liquid crystal layer (thickness: 0.58 μm) on the substrate, which became the second optical compensation layer. The obtained second optical compensation layer has a Re(550) of 0 nm and an Rth(550) of -71 nm.

[0119] Chemical Formula 1

[0120]

[0121] Except for using the first and second optical compensation layers obtained in (i) and (ii) above, and setting the angle between the absorption axis of the polarizer and the slow axis of the first optical compensation layer to 45°, a polarizer with an optical compensation layer having a structure of protective layer / polarizer / first optical compensation layer / second optical compensation layer was obtained in the same manner as in Example 1. Furthermore, except for using this polarizer with an optical compensation layer, an organic EL panel was fabricated in the same manner as in Example 1. The obtained polarizer with an optical compensation layer and organic EL panel were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0122] [Comparative Example 2]

[0123] Except that the thickness of the second optical compensation layer was set to 0.44 μm, a polarizer with an optical compensation layer was obtained in the same manner as Comparative Example 1, consisting of a protective layer / polarizer / first optical compensation layer / second optical compensation layer. The Re(550) of the first optical compensation layer was 139 nm, the Nz coefficient was 1.00, and the Re(450) / Re(550) ratio was 1.00. The Re(550) of the second optical compensation layer was 0 nm, and the Rth(550) was -54. Furthermore, except that this polarizer with an optical compensation layer was used, an organic EL panel was fabricated in the same manner as in Example 1. The obtained polarizer with an optical compensation layer and organic EL panel were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0124] Table 1

[0125]

[0126] ※ Indicates the phase difference (Rth) in the thickness direction.

[0127] [evaluate]

[0128] As shown in Table 1, the polarizer with optical compensation layer in the embodiments of the present invention can maintain excellent anti-reflective properties in the front direction while also exhibiting excellent anti-reflective properties in the tilt direction. Furthermore, according to the embodiments, it was confirmed that the hue in the tilt direction can be set to neutral.

[0129] Industrial availability

[0130] The polarizer with optical compensation layer of the present invention can be applied to organic EL panels.

Claims

1. A polarizer with an optical compensation layer for use in an organic EL panel, comprising a polarizer, a first optical compensation layer, and a second optical compensation layer in sequence. in, The first optical compensation layer exhibits refractive index characteristics of nx≥nz>ny, Re(550) of 90nm~180nm, and Nz coefficient of 0~0.

8. The angle between the absorption axis of the polarizer and the slow axis of the first optical compensation layer is within the range of 0°±10°. The second optical compensation layer exhibits refractive index characteristics of nx > ny = nz, with Re(550) ranging from 100 nm to 180 nm. The angle between the absorption axis of the polarizer and the slow axis of the second optical compensation layer is 35° to 55°. The Re(450) / Re(550) ratio of the first optical compensation layer is 0.99 to 1.03, and the second optical compensation layer satisfies Re(550) > Re(450). Here, Re(450) and Re(550) represent the in-plane phase differences measured with light at 23°C and wavelengths of 450 nm and 550 nm, respectively.

2. A polarizer with an optical compensation layer, used in an organic EL panel, and comprising, in sequence, a polarizer, a first optical compensation layer, and a second optical compensation layer. in, The first optical compensation layer exhibits refractive index characteristics of nx > nz > ny, a Re(550) of 90 nm to 170 nm, and an Nz coefficient of 0.1 to 0.

5. The angle between the absorption axis of the polarizer and the slow axis of the first optical compensation layer is 5° to 25°. The second optical compensation layer exhibits refractive index characteristics of nx > ny = nz, with Re(550) ranging from 60 nm to 140 nm. The angle between the absorption axis of the polarizer and the slow axis of the second optical compensation layer is 50° to 70°. The Re(450) / Re(550) ratio of the first optical compensation layer is 0.99 to 1.03, and the second optical compensation layer satisfies Re(550) > Re(450). Here, Re(450) and Re(550) represent the in-plane phase differences measured with light at 23°C and wavelengths of 450 nm and 550 nm, respectively.

3. An organic EL panel comprising a polarizer with an optical compensation layer as described in claim 1 or 2.

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