Organic el display device

Abstract

To provide an organic EL display device equipped with a polarizing plate on the light emission surface side of an organic EL cell, in which the polarizing plate is made to have ultraviolet shielding capability, and bleeding-out or crystallization of an ultraviolet absorber in an optical layer constituting the polarizing plate is suppressed.SOLUTION: A polarizing plate (10) includes a polarizer (11) having a first main surface and a second main surface, and a retardation layer (13) superimposed on the first main surface side of the polarizer, with the first main surface side of the polarizer located so as to face an organic EL cell (70). The retardation layer (13) includes a first retardation layer the thickness of which is greater than 5 μm and which contains an ultraviolet absorber, and the light transmissivity in a wavelength 380 nm is 60% or less. The first retardation layer is superimposed on the first main surface side of the polarizer via an adhesive layer, and the light transmissivity of the adhesive layer in wavelength 380 nm is large than 60%.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an organic EL display device that includes a polarizing plate on the light exit surface side of an organic EL cell. [Background technology]

[0002] Organic EL display devices equipped with organic EL elements have been put to practical use in display devices such as mobile phones, smartphones, car navigation devices, PC monitors, televisions, etc. In organic EL display devices, a circular polarizer is placed on the viewing side surface of the organic EL cell (organic EL element) to prevent external light from being reflected by the metal electrode (cathode) and being viewed as a mirror surface.

[0003] When ultraviolet light contained in external light is incident on an organic EL element, it may cause deterioration of the organic EL element. In order to suppress deterioration of the organic EL element due to ultraviolet light, it has been proposed to dispose a layer containing an ultraviolet absorber on the viewing side surface of the organic EL cell. For example, Patent Document 1 proposes that ultraviolet absorbing properties are imparted by including an ultraviolet absorber in an adhesive layer for bonding a circular polarizer and an organic EL cell, or an adhesive layer for bonding a cover window to the viewing side surface of a circular polarizer. Patent Document 2 proposes that an ultraviolet absorber is included in an oriented liquid crystal layer constituting the λ / 4 plate of a circular polarizer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-139108 A [Patent Document 2] JP 2017-120431 A Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, in order to suppress the deterioration of the organic EL element due to ultraviolet rays, it is necessary to provide ultraviolet shielding properties to the optical member arranged on the viewing side of the organic EL element. However, as proposed in Patent Document 1, when an ultraviolet absorber is included in the adhesive layer, there is concern about changes in physical properties such as a decrease in transparency and a decrease in adhesion due to bleeding out and crystallization of the ultraviolet absorber. In addition, as proposed in Patent Document 2, when an ultraviolet absorber is added to the aligned liquid crystal layer, since the thickness of the aligned liquid crystal layer is small, it is necessary to increase the concentration of the ultraviolet absorber to increase the ultraviolet shielding properties (sufficiently reduce the amount of ultraviolet rays reaching the organic EL element), and there is concern about poor alignment of the liquid crystal molecules and bleeding out of the ultraviolet absorber. [Means for solving the problem]

[0006] The present invention relates to a polarizing plate for an organic EL display device, which has a retardation layer on one surface (first main surface) of a polarizer. In an organic EL display device, the surface of the polarizing plate on which the retardation layer is arranged (the first main surface side of the polarizer) is disposed so as to face an organic EL cell.

[0007] The retardation layer attached to one surface of the polarizer is composed of one layer or two or more layers, and at least one of the retardation layers (first retardation layer) has a thickness greater than 5 μm and a light transmittance of 60% or less at a wavelength of 380 nm.

[0008] When the retardation layer arranged on one side of the polarizer is a laminated structure of a plurality of retardation layers and includes a second retardation layer in addition to the above-mentioned first retardation layer, the second retardation layer may be arranged between the first retardation layer and the polarizer, or the second retardation layer may be arranged on the side of the first retardation layer opposite to the polarizer. The retardation layer may be a laminated structure of three or more layers.

[0009] The first retardation layer may contain an ultraviolet absorbing agent, and the concentration of the ultraviolet absorbing agent contained in the first retardation layer may be 0.01 to 1.5% by weight.

[0010] In the polarizing plate for an organic EL display device, the slow axis direction of the first retardation layer and the absorption axis direction of the polarizer may be arranged at an angle that is neither parallel nor perpendicular. The angle formed between the slow axis direction of the first retardation layer and the absorption axis direction of the polarizer is, for example, 10° to 80°, and may be 40° to 50°.

[0011] In one embodiment, the first retardation layer is a quarter-wave plate (λ / 4 plate) having a front retardation R(550) of 100 to 180 nm at a wavelength of 550 nm. When the retardation layer disposed on one surface of the polarizer has a laminated structure of a plurality of retardation layers, the retardation layer other than the first retardation layer may be a λ / 4 plate.

[0012] In one embodiment, the first retardation layer has a front retardation R(450) at a wavelength of 450 nm that is smaller than the front retardation R(550) at a wavelength of 550 nm. When the retardation layer disposed on one surface of the polarizer has a laminated structure of a plurality of retardation layers, the retardation layer other than the first retardation layer may satisfy R(450) < R(550).

[0013] The polarizing plate for an organic EL display device may be one in which the above-mentioned retardation layer is laminated on one surface of the polarizer, and a transparent film as a polarizer protection film is laminated on the other surface of the polarizer. The transparent film as a polarizer protection film may have a light transmittance of 15 to 30% at a wavelength of 380 nm. The transparent film as a polarizer protection film may be a cellulose-based resin film such as triacetyl cellulose.

[0014] The light transmittance of the laminate of the polarizer and the transparent film at a wavelength of 380 nm may be 5 to 9%. The light transmittance of the polarizing plate at a wavelength of 380 nm is preferably 4% or less.

[0015] In one embodiment, among the optical layers constituting the polarizing plate, the first retardation layer has the largest thickness.

Advantages of the Invention

[0016] By providing a thick retardation layer with ultraviolet shielding properties, the ultraviolet rays incident on the organic EL element are reduced, and deterioration of the organic EL element can be suppressed. A thick retardation layer can sufficiently reduce the transmittance of ultraviolet rays with a low concentration of ultraviolet absorber, so that the ultraviolet shielding properties required for suppressing deterioration of the organic EL element can be realized while suppressing crystallization and bleeding out of the ultraviolet absorber. [Brief description of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view showing a layered configuration of an organic EL display device according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing a laminated structure of a polarizing plate according to an embodiment. [Diagram 3] FIG. 2 is a cross-sectional view showing a laminated structure of a polarizing plate according to an embodiment. [Figure 4] FIG. 2 is a cross-sectional view showing a laminated structure of a polarizing plate according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] 1 is a cross-sectional view showing a layered structure of an organic EL display device according to one embodiment. An organic EL display device 901 includes a polarizing plate 10 on the light-emitting surface of an organic EL cell 70. A cover window 80 may be disposed on the viewing side surface of the polarizing plate 10 as necessary.

[0019] The organic EL cell 70 may be of a top emission type or a bottom emission type. A top emission type organic EL cell has a metal electrode, an organic light emitting layer, and a transparent electrode in this order on a substrate, and emits light from the surface opposite the substrate. A bottom emission type organic EL cell has a transparent electrode, an organic light emitting layer, and a metal electrode in this order on a substrate, and emits light from the surface on the substrate side.

[0020] A glass substrate or a plastic substrate is used as the substrate of the organic EL cell. In a top-emission organic EL cell, the substrate does not need to be transparent, and a highly heat-resistant film such as a polyimide film may be used as the substrate. The organic light-emitting layer may include an electron transport layer, a hole transport layer, etc., in addition to the organic layer that itself functions as the light-emitting layer. The transparent electrode is a metal oxide layer or a metal thin film, and transmits light from the organic light-emitting layer.

[0021] The metal electrodes of an organic EL cell are light reflective. Therefore, when external light enters the organic EL cell, the light is reflected by the metal electrodes, and the reflected light is seen from the outside as a mirror. By placing a circular polarizer on the visible surface of the organic EL cell, the reflected light at the metal electrodes is prevented from being re-emitted to the outside, improving the visibility and design of the screen.

[0022] [Structure of polarizing plate for organic EL display device] The circularly polarizing plate 10 (polarizing plate for organic EL display devices) includes a retardation layer 13 laminated on one surface (first main surface) of a polarizer 11, and is disposed so that the surface on the retardation layer 13 side faces the organic EL cell 70. The polarizer 11 and the retardation layer 13 are preferably attached to each other via an appropriate adhesive or pressure-sensitive adhesive. An appropriate transparent protective film may be disposed between the polarizer 11 and the retardation layer 13.

[0023] <Polarizer> Examples of the polarizer 11 include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films, which are uniaxially stretched after adsorbing a dichroic substance such as iodine or a dichroic dye, and polyene-based oriented films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride.

[0024] A thin polarizer having a thickness of 10 μm or less can also be used as the polarizer 11. Examples of the thin polarizer include polarizers described in JP-A-51-069644, JP-A-2000-338329, WO2010 / 100917, Japanese Patent No. 4691205, and Japanese Patent No. 4751481. The thin polarizer can be obtained by a manufacturing method including, for example, a step of stretching a polyvinyl alcohol-based resin layer and a resin substrate for stretching in a laminated state, and a step of dyeing with a dichroic material such as iodine.

[0025] <Retardation layer> When the retardation layer 13 has a front retardation of λ / 4 and the angle between the slow axis direction of the retardation layer 13 and the absorption axis direction of the polarizer 11 is 45°, the polarizing plate which is a laminate of the polarizer 11 and the retardation layer 13 functions as a circular polarizing plate for suppressing re-emission of reflected light at the metal electrode of the organic EL cell 70.

[0026] The retardation layer 13 may be a single layer or may be made up of multiple layers. For example, by laminating the polarizer 11, a λ / 2 plate, and a λ / 4 plate so that their optical axes form a predetermined angle, a wideband circular polarizer that functions as a circular polarizer over a wide band of visible light is obtained. In addition to the λ / 4 plate, a retardation layer having a refractive index anisotropy of nx>nz>ny or nz>nx≧ny can be laminated to reduce reflected light in an oblique direction (a direction tilted from the normal direction) of the display device.

[0027] In the present invention, at least one layer (hereinafter referred to as "first retardation layer") of the retardation layer 13 laminated on the first main surface side of the polarizer 11 has a thickness greater than 5 μm and has ultraviolet shielding properties. For example, the first retardation layer can be imparted with ultraviolet shielding properties by containing an ultraviolet absorbing agent. When the retardation layer 13 is composed of a plurality of layers, it is preferable that the layer with the greatest thickness has ultraviolet shielding properties.

[0028] The light transmittance of the first retardation layer at a wavelength of 380 nm is preferably 60% or less, more preferably 55% or less, and may be 50% or less, 45% or less, 40% or less, 35% or less, or 30% or less. The light transmittance of the first retardation layer at a wavelength of 380 nm may be 0%, 0.1% or more, 0.5% or more, or 1% or more.

[0029] The first retardation layer preferably has little visible light absorption and is transparent. The total light transmittance of the first retardation layer is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The light transmittance of the first retardation layer at a wavelength of 440 nm is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more.

[0030] The thickness of the first retardation layer is preferably 10 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, and may be 25 μm or more or 30 μm or more. The greater the thickness of the first retardation layer, the higher the ultraviolet shielding property (small ultraviolet transmittance) can be realized even with a low concentration of ultraviolet absorber. The upper limit of the thickness of the first retardation layer is not particularly limited, but from the viewpoint of the formability of the retardation layer and the thinning of the image display device, it is preferably 250 μm or less, and may be 200 μm or less, 150 μm or less, or 100 μm or less.

[0031] The first retardation layer is preferably a film having self-supporting properties. The tensile modulus (Young's modulus) of the first retardation layer may be about 1 to 4 GPa.

[0032] The material of the first retardation layer is preferably a non-liquid crystal resin material (polymer). By using a non-liquid crystal material, the thickness of the first retardation layer is set within the above range, and high ultraviolet shielding properties can be imparted by adding a low concentration of ultraviolet absorber. Examples of non-liquid crystal resin materials include polycarbonate resins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyarylate resins, sulfone resins such as polysulfone and polyethersulfone, sulfide resins such as polyphenylene sulfide, polyimide resins, cyclic polyolefin resins (polynorbornene resins), polyamide resins, polyolefin resins such as polyethylene and polypropylene, cellulose esters, acrylic resins, styrene resins, maleimide resins, and fumaric acid ester resins.

[0033] (UV absorber) The first retardation layer contains an ultraviolet absorbing agent, and can provide ultraviolet absorbing properties while maintaining the transparency of visible light. Examples of ultraviolet absorbing agents include benzotriazole-based ultraviolet absorbing agents, benzophenone-based ultraviolet absorbing agents, salicylate-based ultraviolet absorbing agents, triazine-based ultraviolet absorbing agents, and cyanoacrylate-based ultraviolet absorbing agents. Triazine-based ultraviolet absorbing agents and benzotriazole-based ultraviolet absorbing agents are preferred because they have high ultraviolet absorbing properties and excellent compatibility with various polymers, and among them, triazine-based ultraviolet absorbing agents containing hydroxyl groups and benzotriazole-based ultraviolet absorbing agents having one benzotriazole skeleton in one molecule are preferred.

[0034] Commercially available products may be used as the ultraviolet absorber. Commercially available triazine-based ultraviolet absorbers include the reaction product of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl and [(alkyloxy)methyl]oxirane (BASF's "TINUVIN 400"), the reaction product of 2-(2,4-dihydroxyphenyl)-4,6-bis-(2,4-dimethylphenyl)-1,3,5-triazine and (2-ethylhexyl)-glycidic acid ester (BASF's "TINUVIN 405"), (2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (BASF's "TINUVIN 460"), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (BASF "TINUVIN 577"), 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (BASF "TINUVIN 479"), 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (BASF "Tinosorb S"), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (ADEKA "ADK STAB LA-46"), 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine (ADEKA "ADK STAB LA-F70", etc.

[0035] Commercially available benzotriazole-based UV absorbers include 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (BASF's "TINUVIN 928"), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (BASF's "TINUVIN PS"), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (BASF's "TINUVIN 900"), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (BASF's "TINUVIN 571"), 2-(2H-benzotriazol-2-yl)-p-cresol (BASF's "TINUVIN P", ADEKA's "ADK STAB"). LA-36G"), 2-(2H-benzotriazol-2-yl)-4-6-bis(1-methyl-1-phenylethyl)phenol (BASF "TINUVIN 234"), 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (BASF "TINUVIN 326", ADEKA "ADK STAB LA-36G"), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (BASF "TINUVIN 328"), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (BASF "TINUVIN 329"), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (ADEKA "ADK STAB LA-29"), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol] (ADEKA "ADK STAB LA-31G"), benzenepropanoic acid and 3-(2H-benzotriazol-2-yl)-5-(1,Examples of such compounds include esters of 1-dimethylethyl)-4-hydroxy (C7-9 side chain and linear alkyl) (BASF's "TINUVIN 384-2"), reaction products of methyl-3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate and polyethylene glycol (BASF's "TINUVIN 1 130"), reaction products of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (BASF's "TINUVIN 213"), and 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole (Sumitomo Chemical's "Sumisorb 250"), etc.

[0036] The content (concentration) of the ultraviolet absorber in the first retardation layer is preferably 1.5% by weight or less, more preferably 1.0% by weight or less, and may be 0.7% by weight or less or 0.5% by weight or less. Since the thickness of the first retardation layer is greater than 5 μm, even if the concentration of the ultraviolet absorber is small, it is possible to provide the ultraviolet shielding property necessary for suppressing deterioration of the organic EL element. Since it is not necessary to increase the concentration of the ultraviolet absorber, changes in surface properties and decreases in transparency caused by precipitation or crystallization of the ultraviolet absorber are suppressed. From the viewpoint of increasing the ultraviolet shielding property, the concentration of the ultraviolet absorber in the first retardation layer is preferably 0.01% by weight or more, more preferably 0.03% by weight or more, and may be 0.05% by weight or more, 0.07% by weight or more, or 0.1% by weight or more.

[0037] <Polarizer protection film> The polarizing plate 10 may be one in which a transparent film 12 is laminated as a polarizer protective film on the viewing side surface (second main surface) of a polarizer 11 via an appropriate adhesive or pressure-sensitive adhesive. The transparent film 12 arranged on the viewing side of the polarizer 11 preferably absorbs little visible light and is transparent. The total light transmittance of the transparent film 12 is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The light transmittance of the transparent film 12 at a wavelength of 440 nm is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more.

[0038] The material of the transparent film 12 is preferably a non-liquid crystal resin material, and specific examples thereof include those mentioned above as the resin material of the first retardation layer. Among them, cellulose-based resins such as triacetyl cellulose are preferred because they have excellent mechanical strength and transparency, and also have excellent adhesion to the polarizer.

[0039] The thickness of the transparent film 12 is not particularly limited, but is preferably 5 to 250 μm and may be 10 to 100 μm or 15 to 50 μm from the viewpoints of handling properties, surface protection properties, etc. A hard coat layer, an antireflection layer, an anti-sticking layer, etc. may be provided on the surface of the transparent film 12 opposite to the polarizer 11 (the surface on the viewing side).

[0040] The transparent film 12 arranged on the viewing side of the polarizer 11 may have ultraviolet shielding properties or may contain an ultraviolet absorbing agent. On the other hand, it is difficult for the transparent film 12 alone to have ultraviolet shielding properties sufficient to prevent deterioration of the organic EL element, and increasing the amount of ultraviolet absorbing agent added to enhance the ultraviolet shielding properties (ultraviolet absorbing properties) may cause problems such as bleed-out or crystallization of the ultraviolet absorbing agent. The light transmittance of the transparent film 12 at a wavelength of 380 nm may be 15 to 30%.

[0041] As described above, in the polarizing plate 10, the retardation layer 13 arranged on the organic EL cell 70 side of the polarizer 11 has an ultraviolet ray shielding property. Therefore, even if the ultraviolet ray shielding property of the transparent film 12 is insufficient, the polarizing plate 10 can have an ultraviolet ray shielding property (for example, a light transmittance of 4% or less at a wavelength of 380 nm) capable of suppressing deterioration of the organic EL element.

[0042] The light transmittance of the polarizing plate 10 at a wavelength of 380 nm is preferably 4% or less, more preferably 3.5% or less, further preferably 3% or less, and may be 2.5% or less or 2% or less. The light transmittance of the laminate of the polarizer 11 and the transparent film 12 (a one-sided protected polarizing plate in which the transparent film 12 is laminated on one side of the polarizer 11) at a wavelength of 380 nm before the retardation layer 13 is attached may be 5 to 9%.

[0043] <Adhesive layer> As described above, the polarizer 11 and the retardation layer 13, and the polarizer 11 and the transparent film 12 are bonded together via an appropriate adhesive or pressure-sensitive adhesive. The thickness of the pressure-sensitive adhesive layer is, for example, about 0.01 to 30 μm.

[0044] The adhesive may be in various forms, such as a water-based adhesive, a solvent-based adhesive, a hot melt adhesive, or an active energy ray curable adhesive. Among these, a water-based adhesive or an active energy ray curable adhesive is preferred because it allows the thickness of the adhesive layer to be small. When using an adhesive that exhibits adhesiveness by a curing reaction after application, the thickness of the adhesive layer is preferably 0.01 to 5 μm, more preferably 0.03 to 3 μm.

[0045] Examples of the polymer component of the aqueous adhesive include vinyl polymer, gelatin, vinyl latex, polyurethane, polyester, epoxy, etc. Among these, vinyl polymer is preferable because of excellent adhesion between the easy-adhesion film and the polarizer, and polyvinyl alcohol resin is particularly preferable. Among polyvinyl alcohol resins, acetoacetyl group-containing polyvinyl alcohol is preferable.

[0046] The active energy ray curable adhesive is an adhesive that can be radically polymerized, cationic polymerized, or anionically polymerized by irradiation with active energy rays such as electron beams or ultraviolet rays. Among them, photo-radical polymerizable adhesives, photo-cationic polymerizable adhesives, and hybrid adhesives that use both photo-cationic polymerization and photo-radical polymerization, in which polymerization is initiated by irradiation with ultraviolet rays, are preferred, since they can be cured with low energy.

[0047] Examples of monomers of radically polymerizable adhesives include compounds having a (meth)acryloyl group and compounds having a vinyl group. Among them, compounds having a (meth)acryloyl group are preferable. Examples of hardening components of cationic polymerizable adhesives include compounds having an epoxy group or an oxetanyl group. The compound having an epoxy group is not particularly limited as long as it has at least two epoxy groups in the molecule, and various commonly known hardening epoxy compounds are used.

[0048] The adhesive may be appropriately selected from those having a base polymer such as an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based polymer, a rubber-based polymer, etc. In particular, an acrylic adhesive is preferred because it has excellent optical transparency, exhibits appropriate wettability and cohesiveness, and is excellent in weather resistance, heat resistance, etc.

[0049] The thickness of the adhesive layer is preferably 1 to 30 μm, more preferably 2 to 25 μm. As described above, since the first retardation film constituting the retardation layer 13 has ultraviolet absorbing properties, the adhesive layer for bonding the polarizer 11 and the retardation layer 13 or the polarizer 11 and the transparent film 12 does not need to have ultraviolet absorbing properties. Therefore, it is not necessary to increase the thickness of the adhesive layer in order to improve the ultraviolet shielding property, and the adhesive layer can be made thin. The thickness of the adhesive layer for bonding the polarizer 11 and the retardation layer 13 or the polarizer 11 and the transparent film 12 may be 15 μm or less, 10 μm or less, or 7 μm or less.

[0050] Among the optical layers constituting the polarizing plate 10, the above-mentioned first retardation layer may be the layer with the greatest thickness. The optical layers constituting the polarizing plate 10 include the polarizer 11, the transparent film 12, one or more optical layers (including the first retardation layer) constituting the retardation layer 13, and a pressure-sensitive adhesive layer for bonding these layers together. By incorporating an ultraviolet absorber into the first retardation layer, which has the greatest thickness among these, it is possible to impart high ultraviolet shielding properties with a low concentration of ultraviolet absorber, and therefore it is possible to provide the polarizing plate 10 with the ultraviolet shielding properties required for suppressing deterioration of the organic EL element while suppressing bleeding out, crystallization, etc. of the ultraviolet absorber.

[0051] An adhesive layer 21 for bonding to a transparent member such as a cover window 80 may be provided on the surface of the polarizing plate 10 on the viewing side. An adhesive layer 22 for bonding to the organic EL cell may be provided on the surface of the polarizing plate 10 on the organic EL cell 70 side. The thickness of these adhesive layers is generally about 5 to 300 μm.

[0052] For the purpose of preventing contamination of the adhesive layers, etc., a separator may be temporarily attached to the surfaces of the adhesive layers 21 and 22. As the separator, a plastic film whose surface is coated with a release agent such as a silicone-based release agent, a long-chain alkyl-based release agent, or a fluorine-based release agent is preferably used.

[0053] [Specific example of retardation layer configuration] As described above, the polarizing plate 10 for an organic EL display device has the retardation layer 13 on one surface of the polarizer 11, and functions as a circular polarizing plate to suppress re-emission of reflected light by metal electrodes of the organic EL cell 70. The retardation layer 13 is composed of one or more optical layers, at least one of which (the first retardation layer) has ultraviolet light shielding properties, and therefore contributes to suppressing deterioration of the organic EL element. A specific example of the configuration of the retardation layer 13 of the polarizing plate 10 will be described below.

[0054] The retardation plate 102 shown in Fig. 2 is configured such that the retardation layer 13 consists of a single retardation layer 131. The retardation layer 131 is a λ / 4 plate, and the front retardation R(550) at a wavelength of 550 nm is preferably 100 to 180 nm, more preferably 110 to 170 nm, still more preferably 120 to 150 nm, and may be 125 to 145 nm.

[0055] The angle formed between the slow axis direction of the retardation layer 131 and the absorption axis direction of the polarizer 11 is 10 to 90°, preferably 40 to 50°, and may be 43 to 47° or 44 to 46°. If the retardation layer 131 is a λ / 4 plate and the angle formed between the slow axis direction of the retardation layer 131 and the absorption axis direction of the polarizer 11 is around 45°, the polarizing plate 102 acts as a circular polarizing plate.

[0056] The retardation layer 131, which is a λ / 4 plate, may have a front retardation R(450) at a wavelength of 450 nm that is smaller than the front retardation R(550) at a wavelength of 550 nm. In addition to R(450) < R(550), the λ / 4 plate may satisfy R(650) > R(550) at a wavelength of 650 nm, i.e., R(550) < R(650). By using a λ / 4 plate having a larger retardation at longer wavelengths, the circular polarizing plate 10 functions as a circular polarizing plate in a wide wavelength region of visible light, thereby reducing the coloration of the reflected light.

[0057] The R(450) / R(550) of the retardation layer 131 may be 0.70 to 0.95, 0.75 to 0.90, or 0.80 to 0.87. The R(650) / R(550) of the retardation layer 131 may be 1.05 to 1.30, 1.10 to 1.25, or 1.13 to 1.20.

[0058] The retardation layer 131 is preferably a stretched film. The retardation layer 131 is obtained as a stretched film by stretching a resin film in a predetermined direction to impart optical anisotropy such that the front retardation R(550) falls within the above range. The stretching method is not particularly limited, and may be free-end uniaxial stretching using a roll stretching machine. A heat shrinkable film may be attached to one or both sides of the resin film, and the film may be excessively shrunk in a direction perpendicular to the stretching direction (width direction) by utilizing the shrinking action of the heat shrinkable film at the same time as stretching, thereby stretching the film so as to increase the thickness. As the stretching method, transverse stretching, longitudinal and transverse biaxial stretching, or oblique stretching using a tenter stretching machine may be adopted.

[0059] When the resin material constituting the resin film has positive intrinsic birefringence, a retardation layer (positive A plate) having a refractive index anisotropy of nx>ny≒nz can be obtained by free end uniaxial stretching. nx is the refractive index in the in-plane slow axis direction, ny is the refractive index in the in-plane fast axis direction, and nz is the refractive index in the thickness direction.

[0060] When the film is stretched while being excessively shrunk in the width direction by utilizing the shrinking force of the heat shrink film, the refractive index nz in the thickness direction becomes larger than the refractive index ny in the width direction (fast axis direction), so that a retardation layer having a refractive index anisotropy of nx>nz>ny is obtained. Since the retardation layer having a refractive index anisotropy of nx>nz>ny has a small change in retardation depending on the viewing angle, if a λ / 4 plate having a refractive index anisotropy of nx>nz>ny is used as the retardation layer 131, it is possible to reduce reflected light not only in the front direction (normal direction) of the display device, but also in oblique directions.

[0061] As described above, in the polarizing plate 102, the polarizer 11 and the retardation layer 131 are laminated so that their optical axes are neither parallel nor perpendicular (for example, the angle between the absorption axis direction and the slow axis direction is 45°). In order to obtain a circular polarizing plate by laminating the polarizer and the retardation layer by roll-to-roll, it is preferable to use an obliquely stretched film as the retardation layer 13. For example, a long circular polarizing plate can be produced by laminating an obliquely stretched film stretched so that the slow axis direction is 45° to the longitudinal direction (transport direction) and a polarizer having an absorption axis in the longitudinal direction by roll-to-roll, and thus the production efficiency and yield can be significantly improved. The obliquely stretched film generally has a refractive index anisotropy of nx>ny>nz.

[0062] 3 shows another example of the configuration of a polarizing plate for an organic EL display device, and in the polarizing plate 103, the retardation layer 13 is composed of two layers, a retardation layer 131 and a retardation layer 133. The retardation layer 131 is a λ / 4 plate similar to the retardation layer in the polarizing plate 102 in Fig. 2. The retardation layer 133 has a refractive index anisotropy of nz>nx≧ny.

[0063] For example, when the retardation layer 131 has a refractive index anisotropy of nx>ny≧nz and the retardation layer 133 is a positive C plate having a refractive index anisotropy of nz>nx≒ny, the retardation of the retardation layer 131 in the diagonal direction is cancelled out by the retardation layer 133. Therefore, the retardation layer 13, which is a laminate of the retardation layer 131 and the retardation layer 133, has a refractive index anisotropy of nx>nz>ny and exhibits small change in retardation due to the viewing angle, and therefore, it is possible to reduce reflected light not only from the front of the display device but also from diagonal directions.

[0064] Examples of the positive C plate having a refractive index anisotropy of nz>nx≒ny include a homeotropic alignment liquid crystal layer in which liquid crystal molecules are aligned in the normal direction (thickness direction) of the retardation layer, a coating film in which a polymer having a negative intrinsic birefringence is aligned in-plane by coating, and a stretched film in which a film of a polymer having a negative intrinsic birefringence is biaxially stretched so that the front retardation is approximately 0. nx≒ny is not limited to the case where nx and ny are completely equal, and it is sufficient that the front retardation R(550) is 10 nm or less. The front retardation R(550) of the positive C plate is preferably 5 nm or less, and may be 3 nm or less or 1 nm or less.

[0065] When the retardation layer 13 has a laminated structure of a retardation layer (λ / 4 plate) 131 having a refractive index anisotropy of nx>ny≧nz and a retardation layer (positive C plate) 133 having a refractive index anisotropy of nz>nx≒ny, either one of the retardation layer 131 and the retardation layer 133 may be a first retardation layer having ultraviolet shielding properties. When ultraviolet shielding properties are imparted by including an ultraviolet absorbing agent, it is preferable that the retardation layer having a relatively large thickness includes the ultraviolet absorbing agent and has a light transmittance of 60% or less at a wavelength of 380 nm.

[0066] For example, when the retardation layer 131 is a stretched film and the retardation layer 133 is a positive C plate made of an oriented liquid crystal layer, a stretched film is generally thicker than a liquid crystal layer, so the retardation layer 131 having a relatively larger thickness is the first retardation layer, and it is preferable that the light transmittance at a wavelength of 380 nm is 60% or less, and the retardation layer 133 (second retardation layer) in which nz>nx≒ny does not need to have ultraviolet ray blocking properties.

[0067] When both the retardation layer 131 and the retardation layer 133 are polymer films made of non-liquid crystal resin materials, it is sufficient that either the retardation layer 131 or the retardation layer 133 has ultraviolet shielding properties, and it is preferable that the retardation layer having a relatively large thickness has ultraviolet shielding properties and has a light transmittance of 60% or less at a wavelength of 380 nm. For example, when the thickness of the retardation layer 131 is smaller than the thickness of the retardation layer 133, it is preferable that the retardation layer 131 as a λ / 4 plate is a first retardation layer having ultraviolet shielding properties, and the second retardation layer 133 as a positive C plate does not have to have ultraviolet shielding properties. Both the retardation layer 131 and the retardation layer 133 may have ultraviolet shielding properties.

[0068] FIG. 3 illustrates a form in which a retardation layer 133, which is a positive C plate, is arranged on the surface of the retardation layer 131, which is a λ / 4 plate, opposite the polarizer 11. However, the retardation layer 133 may be arranged between the polarizer 11 and the retardation layer 131.

[0069] 4 shows another example of the configuration of a polarizing plate for an organic EL display device, and in the polarizing plate 104, the retardation layer 13 is composed of two layers, a retardation layer 131 and a retardation layer 135. The retardation layer 131 is a λ / 4 plate similar to the retardation layer in the polarizing plate 102 in Fig. 2. The retardation layer 135 has a refractive index anisotropy of nx>nz>ny.

[0070] The retardation layer 135 having refractive index anisotropy of nx>nz>ny can have the effect of canceling the oblique retardation of the retardation layer 131, similar to the retardation layer 133 in the above-mentioned polarizing plate 103. In addition, by arranging the retardation layer 135 so that its slow axis direction is parallel or perpendicular to the absorption axis direction of the polarizer 11, the retardation layer 135 has the effect of compensating for the deviation of the apparent optical axis direction of the polarizer 11 when viewed from an oblique direction.

[0071] The angle between the slow axis direction of the retardation layer 135 and the absorption axis direction of the polarizer 11 is preferably 0° to 5° or 85° to 90°, more preferably 0° to 3° or 87° to 90°, and even more preferably 0° to 1° or 89° to 90°.

[0072] The retardation layer 135 has an NZ coefficient defined as NZ=(nx-nz) / (nx-ny) greater than 0 and less than 1. The NZ coefficient of the retardation layer 135 is preferably 0.1 to 0.9, more preferably 0.2 to 0.8, and further preferably 0.3 to 0.7, and may be 0.4 to 0.6 or 0.45 to 0.55.

[0073] The retardation layer 135 has a front retardation R(550) at a wavelength of 550 nm of, for example, 100 to 400 nm. The retardation layer 135 may have R(550) of 200 to 350 nm, 220 to 330 nm, 240 to 310 nm, 250 to 300 nm, or 260 to 290 nm.

[0074] When the retardation layer 13 has a laminated structure of a retardation layer (λ / 4 plate) 131 having a refractive index anisotropy of nx>ny≧nz and a retardation layer 135 having a refractive index anisotropy of nx>ny>nz, either one of the retardation layer 131 and the retardation layer 135 may be a first retardation layer having ultraviolet ray blocking properties, or both the retardation layer 131 and the retardation layer 135 may have ultraviolet ray blocking properties.

[0075] The configuration of the retardation layer 13 in the polarizing plate for an organic EL display device of the present invention is not limited to the embodiment shown in Figures 2 to 4, and it is sufficient that at least one layer constituting the retardation layer has a thickness greater than 5 μm and a light transmittance of 60% or less at a wavelength of 380 nm. The retardation layer 13 may have a laminated configuration of three or more retardation layers.

[0076] [Organic EL epidermal device] An organic EL display device is formed by bonding the above-mentioned polarizing plate 10 for an organic EL display device to the light emission surface of the organic EL cell 70. A touch panel (not shown) may be disposed between the organic EL cell 70 and the polarizing plate 10.

[0077] A cover window 80 may be disposed on the polarizing plate 10 for the purpose of preventing damage to the organic EL cell 7 due to impact from the outer surface. A transparent plate having appropriate mechanical strength and thickness is used as the cover window 80. As such a transparent plate, a transparent resin plate such as an acrylic resin, a polycarbonate resin, or a transparent polyimide resin, or a glass plate is used. The thickness of the cover window 80 is, for example, about 20 to 2000 μm. The cover window 80 may be integrated with a touch panel sensor. An anti-reflection layer, a hard coat layer, or the like may be provided on the viewing side surface of the cover window 80.

[0078] As described above, it is preferable to use the adhesive layers 21, 22 for bonding the polarizing plate 10 to the organic EL cell 70 and for bonding the polarizing plate 10 to the cover window 80. In the present invention, since the polarizing plate 10 has an ultraviolet shielding property, even if the adhesive layers 21, 22 do not contain an ultraviolet absorber, the amount of ultraviolet light contained in external light that enters the organic EL cell 70 is reduced, and deterioration of the organic EL element can be suppressed. EXAMPLES

[0079] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0080] [Adhesive sheet manufacturing example] <Adhesive sheet A> In a reaction vessel, 92 parts by weight of butyl acrylate, 5 parts by weight of N-acryloylmorpholine (ACMO), 2.9 parts by weight of acrylic acid, and 0.1 parts by weight of 2-hydroxyethyl acrylate as monomers, and 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator were added together with ethyl acetate, and the mixture was reacted at 55°C for 8 hours under a nitrogen gas stream. Ethyl acetate was then added to the reaction solution to obtain a solution of an acrylic polymer having a weight average molecular weight of 1.78 million. This solution was mixed with 0.15 parts by weight of dibenzoyl peroxide (manufactured by Nippon Oil & Fats Co., Ltd.'s "Niper BMT") and 0.6 parts by weight of trimethylolpropane / tolylene diisocyanate adduct (manufactured by Tosoh Corporation's "Coronate L") as crosslinking agents per 100 parts by weight of the polymer to obtain a pressure-sensitive adhesive composition.

[0081] The above pressure-sensitive adhesive composition was applied to the release-treated surface of a release film (polyethylene terephthalate film treated with silicone release agent), and then dried and crosslinked at 150° C. to prepare a pressure-sensitive adhesive sheet having a thickness of 5 μm.

[0082] <Adhesive sheet B> In preparing the adhesive composition, in addition to the crosslinking agent, 6 parts by weight of an ultraviolet absorber (5,5'-bis(2-ethylhexyloxy)-2,2'-[6-(4-methoxyphenyl)-1,3,5-triazine-2,4-diyl]diphenol; "Tinosorb S" manufactured by BASF) was blended into the polymer solution. Otherwise, an adhesive sheet having a thickness of 5 μm was obtained in the same manner as in the preparation of adhesive sheet A.

[0083] <Adhesive sheet C> In the preparation of the adhesive composition, the blending amount of the ultraviolet absorber was changed to 0.8 parts by weight, and the thickness of the adhesive sheet was changed to 40 μm. Otherwise, an adhesive sheet having a thickness of 40 μm was obtained in the same manner as in the preparation of adhesive sheet B.

[0084] [Retardation film manufacturing example] <Retardation film A> (Preparation of Polycarbonate (PC) Resin) Into a reaction vessel, 38.06 parts by weight of bis[9-(2-phenoxycarbonylethyl)fluoren-9-yl]methane, 53.73 parts by weight of isosorbide (POLYSORB manufactured by Rocket Fleuret), 9.64 parts by weight of 1,4-cyclohexanedimethanol (cis-trans mixture, manufactured by SK Chemicals), and 81.28 parts by weight of diphenyl carbonate (manufactured by Mitsubishi Chemicals), as well as calcium acetate monohydrate as a catalyst, were charged, and after reducing the pressure and replacing with nitrogen, the raw materials were dissolved by stirring at 150°C for about 10 minutes under a nitrogen gas stream. After heating to 220°C, the reaction was carried out at normal pressure for 60 minutes. Then, the pressure was reduced from normal pressure to 13.3 kPa, and the pressure was maintained for 30 minutes, and the generated phenol was extracted from the reaction system. Next, the pressure was reduced to 0.10 kPa or less while heating to 240°C, and the generated phenol was extracted from the reaction system. After the predetermined stirring torque was reached, the pressure was returned to normal pressure with nitrogen to stop the reaction. The produced polycarbonate was extruded into water, and the strands were cut to obtain polycarbonate (PC) resin pellets.

[0085] (Preparation of Stretched Film) The polycarbonate resin pellets were used to prepare an unstretched film having a thickness of 100 μm by melt extrusion, which was then obliquely stretched at a temperature of 137° C. and a stretching ratio of about 2.5 times using a tenter-type stretching machine capable of independently controlling the moving speed of the left and right clips, to obtain a stretched retardation film whose slow axis direction was 45° to the longitudinal direction of the film.

[0086] <Retardation film B> In preparing the polycarbonate resin, 0.2 parts by weight of a triazine-based ultraviolet absorber (2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine; ADEKA "ADEKA STAB LA-F70") was blended with 100 parts by weight of the polycarbonate melt after the reaction was stopped to obtain polycarbonate resin pellets containing an ultraviolet absorber. A stretched retardation film was produced in the same manner as in the production of retardation film A, except that the pellets were used.

[0087] <Retardation films C and D> In preparing the polycarbonate resin, the amount of the ultraviolet absorber (ADK STAB LA-F70) was changed to 0.3 parts by weight (Retardation Film C) and 1.0 part by weight (Retardation Film D). Otherwise, the stretched retardation films were prepared in the same manner as in the preparation of Retardation Film B.

[0088] <Retardation films E and F> In the preparation of the polycarbonate resin, the type of ultraviolet absorber was changed to 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol], and the blending amount was 0.7 parts by weight (retardation film E) and 0.9 parts by weight (retardation film F). Otherwise, the stretched retardation films were prepared in the same manner as in the preparation of the retardation film B.

[0089] <Retardation Film G> In the preparation of the polycarbonate resin, the blending amount of the ultraviolet absorber (Adeka STAB LA-F70) was changed to 0.05 parts by weight, polycarbonate resin pellets were prepared, and an unstretched film having a thickness of 235 μm was prepared by melt extrusion. A biaxially stretched polypropylene film (Toray "Treyfan") laminated with an adhesive sheet was attached to both sides of this film. This laminate was free-end uniaxially stretched to about 1.5 times in the longitudinal direction at a temperature of 145°C using a roll stretching machine. Thereafter, the biaxially stretched propylene films on both sides were peeled off to obtain a stretched retardation film in which the refractive index nz in the thickness direction was greater than the refractive index ny in the width direction (advance axis direction).

[0090] <Stretched film H> 100 parts by weight of cyclic olefin polymer (COP) resin pellets (JSR "ARTON R5000") and 0.05 parts by weight of ultraviolet absorber (ADK STAB LA-F70) were dissolved in methylene chloride, and a 130 μm thick unstretched film was produced by the solution film formation method. A biaxially stretched polypropylene film (Toray "Treyfan") laminated with an adhesive sheet was attached to both sides of this film, and the free end was uniaxially stretched to about 1.3 times in the longitudinal direction at a temperature of 140 ° C. using a roll stretching machine, and the biaxially stretched propylene films on both sides were peeled off to obtain a stretched retardation film with a refractive index nz in the thickness direction larger than the refractive index ny in the width direction.

[0091] <Retardation Film I> (Preparation of Fumaric Acid Ester (FAE)-Based Resins) Hydroxypropylmethylcellulose (Metolose 60SH-50 manufactured by Shin-Etsu Chemical Co., Ltd.): 48 parts by weight, distilled water: 15,600 parts by weight, diisopropyl fumarate: 8,161 parts by weight, 3-ethyl-3-oxetanylmethyl acrylate: 240 parts by weight, and t-butyl peroxypivalate as a polymerization initiator were added to an autoclave, and after nitrogen bubbling was performed for 1 hour, the mixture was kept at 49°C for 24 hours while stirring to perform radical suspension polymerization. The mixture was then cooled to room temperature, and the suspension containing the produced polymer particles was centrifuged. The obtained polymer particles were washed with distilled water and methanol, and then dried under reduced pressure at 80°C to obtain a fumarate ester-based resin.

[0092] (Film Creation) The above fumaric acid ester resin was dissolved in a mixed solvent of toluene and methyl ethyl ketone to prepare a resin solution, and a 6μm-thick unstretched film (coated retardation film) was fabricated by the solution casting method.

[0093] <Retardation Film J> In the preparation of the film, 0.9 parts by weight of an ultraviolet absorber (ADK STAB LA-F70) was added to 100 parts by weight of the fumaric acid ester resin to prepare a solution. Except for this, the coating retardation film was prepared in the same manner as in the preparation of the retardation film J.

[0094] [Evaluation of adhesive sheets and retardation films] <Precipitation and crystallization of UV absorbers> The sample was cut into a size of 200 mm x 300 mm and kept in a thermo-hygrostat at a temperature of 20°C and a relative humidity of 98% for 500 hours, then removed and observed under a microscope to check for the presence or absence of precipitation or crystallization of the UV absorber.

[0095] <Transmittance> The transmission spectrum was measured using an ultraviolet-visible spectrophotometer (Hitachi High-Tech's "U-4100"), and the light transmittance at a wavelength of 380 nm was read from the obtained spectrum.

[0096] <Lettering> Retardation films A to J were cut into a size of 50 mm x 50 mm, and the front retardation at a wavelength of 550 nm and the retardation at a 40° tilt with the slow axis direction as the center of rotation were measured using a polarization / retardation measurement system (Axometrics' "AxoScan"). From these measurements, the front retardation Re = (nx-ny) x d and the thickness retardation Rth = (nx-nz) x d at a wavelength of 550 nm were calculated. nx is the in-plane refractive index in the slow axis direction, ny is the in-plane refractive index in the fast axis direction, nz is the refractive index in the thickness direction, and d is the thickness of the retardation film. The average refractive index measured by an Abbe refractometer manufactured by Atago Co., Ltd. was used to calculate the thickness retardation.

[0097] Table 1 shows the materials (resin types) of the pressure-sensitive adhesive sheets A to C and the retardation films A to J, the type and amount of ultraviolet absorber (UVA) added, thickness, and evaluation results.

[0098] [Table 1]

[0099] [Preparation of circular polarizing plate] <Preparation of one-sided protected polarizing plate> (Preparation of polarizer) One side of a 100 μm-thick amorphous polyester film (polyethylene terephthalate / isophthalate; glass transition temperature 75°C) was subjected to a corona treatment, and an aqueous solution containing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified polyvinyl alcohol (Nippon Synthetic Chemical Industry "Gosefimer Z200"; degree of polymerization 1200, degree of acetoacetyl modification 4.6%, degree of saponification ≥ 99.0 mol%) in a weight ratio of 9:1 was applied to the corona-treated surface and dried at 25°C to produce a laminate in which an 11 μm-thick PVA-based resin layer was provided on the amorphous polyester film substrate.

[0100] This laminate was free-end uniaxially stretched 2.0 times in the longitudinal direction in an oven at 120 ° C. The stretched laminate was immersed in a 4% boric acid aqueous solution at 30 ° C for 30 seconds, and then immersed in a dyeing solution (0.2% iodine, 1.0% potassium iodide aqueous solution) at 30 ° C for 60 seconds. Next, it was immersed in a crosslinking solution (3% potassium iodide, 3% boric acid aqueous solution) at 30 ° C for 30 seconds to perform a crosslinking treatment. Thereafter, the laminate was free-end uniaxially stretched in the longitudinal direction to a total stretch ratio of 5.5 times while being immersed in a 4% boric acid, 5% potassium iodide aqueous solution at 70 ° C. Then, the laminate was immersed in a cleaning solution (4% potassium iodide aqueous solution) at 30 ° C. to obtain a laminate having a PVA-based polarizer having a thickness of 5 μm on an amorphous polyester film substrate.

[0101] (Laminating the polarizer protective film) A UV-curable adhesive was prepared by mixing 40 parts by weight of N-hydroxyethylacrylamide (HEAA), 60 parts by weight of acryloylmorpholine (ACMO), and 3 parts by weight of a photopolymerization initiator (BASF's "Irgacure 819"). This adhesive was applied to the surface of the polarizer of the laminated body with a thickness of about 1 μm, and a 25 μm-thick triacetyl cellulose (TAC) film was laminated on top of it as a polarizer protective film, and the cumulative irradiation dose was 1000 / mJ / cm. 2The adhesive was cured by irradiating ultraviolet light of 1000 nm. The amorphous polyester film substrate was then peeled off to obtain a single-protected polarizing plate in which a TAC film was attached to one side of a thin polarizer with a thickness of about 5 μm via an adhesive. The light transmittance of this single-protected polarizing plate at a wavelength of 380 nm was 6.6%.

[0102] <Comparative Example 1> A circular polarizing plate was produced by laminating the retardation film A to the polarizer side surface of the one-sided protected polarizing plate via the adhesive sheet A using a roll laminator. The angle between the absorption axis of the polarizer and the slow axis (stretching direction) of the retardation film was 45°.

[0103] <Examples 1 to 5, Comparative Examples 2 and 3> A circularly polarizing plate was produced in the same manner as in Comparative Example 1, except that the types of the pressure-sensitive adhesive sheet and the retardation film were changed as shown in Table 1.

[0104] <Example 6> The one-sided protected polarizing plate and the retardation film G were cut into rectangles, and the retardation film G was attached to the polarizer side surface of the one-sided protected polarizing plate via the adhesive sheet A to prepare a circular polarizing plate. The angle between the absorption axis of the polarizer and the slow axis (stretching direction) of the retardation film was 45°.

[0105] <Example 7> Using a roll laminator, retardation film H was laminated onto the polarizer side surface of the one-sided protected polarizing plate via adhesive sheet A, and retardation film A was laminated onto retardation film H via adhesive sheet A to produce a circular polarizing plate. The absorption axis of the polarizer and the slow axis (stretching direction) of retardation film H were parallel, and the angle between the absorption axis of the polarizer and the slow axis of retardation film A was 45°.

[0106] <Example 8> Using a roll laminator, retardation film A was laminated to the polarizer side surface of the one-sided protected polarizing plate via adhesive sheet A, and retardation film J was laminated onto retardation film A via adhesive sheet A to produce a circular polarizing plate. The angle between the absorption axis of the polarizer and the slow axis of retardation film A was 45°.

[0107] <Examples 9 and 10> A circularly polarizing plate having two layers of retardation film on one side of a polarizer was produced in the same manner as in Example 8, except that the type of retardation film was changed as shown in Table 2.

[0108] Table 2 shows the laminate structure of the circular polarizing plates of the examples and comparative examples, and the light transmittance of the circular polarizing plates at a wavelength of 380 nm.

[0109] [Table 2]

[0110] As shown in Table 1, when an ultraviolet absorber was blended into the adhesive that constituted the adhesive sheet, precipitation and crystallization of the ultraviolet absorber occurred in a high humidity environment, whereas when an ultraviolet absorber was blended into the retardation film, no precipitation or crystallization of the ultraviolet absorber was observed, and the product had a good appearance.

[0111] By including an ultraviolet absorber in the retardation film, it is possible to provide ultraviolet shielding properties equal to or greater than those achieved when an ultraviolet absorber is included in the pressure-sensitive adhesive sheet (Comparative Examples 2 and 3) without causing crystallization or precipitation of the ultraviolet absorber. Because the retardation film is thick, it can be seen that even a low concentration of ultraviolet absorber of 1% or less exhibits excellent ultraviolet shielding properties. [Explanation of symbols]

[0112] 10,102,103,104 Polarizing plate (circular polarizing plate) 11 Polarizer 12 Transparent film (polarizer protection film) 13 Retardation layer 131 Retardation layer (λ / 4 plate) 133,135 Retardation layer 70 Organic EL Cells 80 Cover Window 21, 22 Adhesive layer 901 Organic EL display device

Claims

1. An organic EL display device comprising an organic EL cell and a polarizing plate disposed on a light emission surface side of the organic EL cell, the polarizing plate includes a polarizer having a first main surface and a second main surface, and a first retardation layer laminated on the first main surface side of the polarizer via a pressure-sensitive adhesive layer, and is disposed so that a surface on which the first retardation layer is disposed faces the organic EL cell; the first retardation layer contains an ultraviolet absorber, has a thickness of more than 5 μm, and has a light transmittance of 60% or less at a wavelength of 380 nm; The pressure-sensitive adhesive layer has a light transmittance of more than 60% at a wavelength of 380 nm. Organic EL display device.

2. 2. The organic electroluminescence display device according to claim 1, wherein the polarizing plate has a light transmittance of 4% or less at a wavelength of 380 nm.

3. 3. The organic electroluminescence display device according to claim 1, wherein the concentration of the ultraviolet absorbing agent contained in the first retardation layer is 0.01 to 1.5% by weight.

4. 4. The organic electroluminescence display device according to claim 1, wherein an angle between a slow axis direction of the first retardation layer and an absorption axis direction of the polarizer is 10° to 80°.

5. 4. The organic electroluminescence display device according to claim 1, wherein an angle between a slow axis direction of the first retardation layer and an absorption axis direction of the polarizer is 40° to 50°.

6. 6. The organic electroluminescence display device according to claim 1, wherein the first retardation layer has a front retardation R(550) at a wavelength of 550 nm of 100 to 180 nm.

7. 7. The organic electroluminescence display device according to claim 1, wherein the first retardation layer has a front retardation R(450) at a wavelength of 450 nm smaller than a front retardation R(550) at a wavelength of 550 nm.

8. The organic electroluminescence display device according to any one of claims 1 to 7, wherein the first retardation layer is a stretched film.

9. 8. The organic electroluminescence display device according to claim 1, wherein the first retardation layer is an obliquely stretched film.

10. The polarizing plate includes a second retardation layer between the polarizer and the first retardation layer, or on the surface of the first retardation layer opposite the polarizer. The organic electroluminescence display device according to any one of claims 1 to 9.

11. The organic electroluminescence display device according to claim 10 , wherein the second retardation layer has an in-plane slow axis refractive index nx, an in-plane fast axis refractive index ny, and a thickness direction refractive index nz that satisfy nz>nx≧ny.

12. The organic electroluminescence display device according to claim 10 , wherein the first retardation layer and the second retardation layer are attached to each other via a pressure-sensitive adhesive layer having a light transmittance of more than 60% at a wavelength of 380 nm.

13. 13. The organic electroluminescence display device according to claim 1, wherein the polarizing plate comprises a transparent film laminated on a second main surface side of the polarizer.

14. 14. The organic electroluminescence display device according to claim 13, wherein the transparent film has a light transmittance of 15 to 30% at a wavelength of 380 nm.

15. 15. The organic electroluminescence display device according to claim 13, wherein the transparent film is a cellulose-based resin film.

16. 16. The organic electroluminescence display device according to claim 13, wherein a laminate of the polarizer and the transparent film has a light transmittance of 5 to 9% at a wavelength of 380 nm.

17. 17. The organic electroluminescence display device according to claim 1, wherein the first retardation layer has the largest thickness among the optical layers constituting the polarizing plate.

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