TW202303201A - Polarizing plate and organic EL display device - Google Patents

Abstract

The polarizing plate (10) of the present invention has a polarizing element (11) having a first main surface and a second main surface, and a retardation layer (13) laminated on the first main surface side of the polarizing element, and the polarizing element The organic EL unit ( 70 ) is disposed and used on the first main surface side. The phase difference layer (13) includes a first phase difference layer with a thickness greater than 5 μm and a light transmittance of 60% or less at a wavelength of 380 nm. The polarizing plate has ultraviolet shielding properties, suppresses bleeding or crystallization of the ultraviolet absorber, and can be favorably used as a polarizing plate for an organic EL display device.

Description

Polarizing plate and organic EL display device

The invention relates to a polarizing plate and an organic EL display device.

Organic EL (Electroluminescence) display devices equipped with organic EL elements are being put into practical use in display devices such as mobile phones, smart phones, car navigation devices, computer monitors, and televisions. In an organic EL display device, a circular polarizing plate is arranged on the viewing side surface of the organic EL unit (organic EL element) in order to prevent external light from being reflected by the metal electrode (cathode) and viewed as a mirror.

When ultraviolet rays included in external light enter the organic EL element, it may cause deterioration of the organic EL element. In order to suppress deterioration of an organic EL element caused by ultraviolet rays, it has been proposed to arrange a layer containing an ultraviolet absorber on the viewing side surface of an organic EL unit. For example, it is proposed in Patent Document 1 that UV absorption is included in the adhesive layer used to bond the circular polarizing plate and the organic EL unit, or in the adhesive layer used to bond the cover window on the viewing side surface of the circular polarizing plate. agent to impart UV absorption. In Patent Document 2, it is proposed to include an ultraviolet absorber in an alignment liquid crystal layer of a λ/4 plate constituting a circular polarizing plate. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2020-139108 [Patent Document 2] Japanese Patent Laid-Open No. 2017-120431

[Problem to be solved by the invention]

As described above, in order to suppress the deterioration of the organic EL element due to ultraviolet rays, it is necessary to impart ultraviolet shielding properties to the optical member arranged on the viewing side of the organic EL element. However, if a UV absorber is included in the adhesive layer as proposed in Patent Document 1, there are concerns about changes in physical properties such as decrease in transparency or decrease in adhesiveness due to bleeding or crystallization of the UV absorber. Also, in the case of adding an ultraviolet absorber to the aligned liquid crystal layer as proposed in Patent Document 2, since the thickness of the aligned liquid crystal layer is small, in order to improve the ultraviolet shielding property (sufficiently reduce the amount of ultraviolet rays reaching the organic EL element) However, it is necessary to increase the concentration of the ultraviolet absorber, thereby worrying about poor alignment of the liquid crystal molecules or leakage of the ultraviolet absorber. [Technical means to solve the problem]

The present invention relates to a polarizing plate for an organic EL display device provided with a retardation layer on one surface (first main surface) of a polarizing element. In the organic EL display device, the surface of the polarizing plate on which the retardation layer is arranged (the first main surface side of the polarizing element) is arranged so as to face the organic EL unit.

The retardation layer attached to one side of the polarizing element includes one or more layers, at least one retardation layer (the first retardation layer) has a thickness greater than 5 μm, and has a light transmittance of 60 at a wavelength of 380 nm %the following.

When the retardation layer arranged on one surface of the polarizing element is composed of a laminate of plural retardation layers, and in addition to the above-mentioned first retardation layer also includes a second retardation layer, the second retardation layer can be arranged on the second retardation layer. Between a retardation layer and the polarizing element, it can also be disposed on the surface of the first retardation layer opposite to the polarizing element. The retardation layer may also be composed of three or more laminated layers.

The first retardation layer may contain an ultraviolet absorber, and the concentration of the ultraviolet absorber contained in the first retardation layer may also be 0.01 to 1.5% by weight.

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

In one embodiment, the first phase difference layer is a 1/4 wavelength plate (λ/4 plate) with a front phase retardation R(550) of 100-180 nm at a wavelength of 550 nm. When the retardation layer arranged on one surface of the polarizing element is composed of a laminate of a plurality of retardation layers, the retardation layer other than the first retardation layer may be a λ/4 plate.

In one embodiment, the front phase retardation R(450) of the first retardation layer at a wavelength of 450 nm is smaller than the front phase retardation R(550) at a wavelength of 550 nm. When the retardation layer arranged on one surface of the polarizing element is composed of a plurality of retardation layers, the retardation layer other than the first retardation layer can satisfy R(450)<R(550).

The polarizing plate for an organic EL display device may have the above-mentioned retardation layer on one surface layer of the polarizing element, and a transparent film serving as a protective film of the polarizing element on the other surface layer of the polarizing element. The light transmittance of the transparent film used as a protective film for polarizing elements at a wavelength of 380 nm can be 15-30%. The transparent film as a polarizer protective film may be a cellulose-based resin film such as triacetyl cellulose.

The light transmittance of the laminate of the polarizing element and the transparent film at a wavelength of 380 nm can also be 5-9%. The light transmittance of the polarizing plate at a wavelength of 380 nm is preferably below 4%.

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

By imparting ultraviolet shielding properties to the thick retardation layer, the incident ultraviolet rays to the organic EL element can be reduced, thereby suppressing deterioration of the organic EL element. A thick retardation layer can sufficiently reduce the transmittance of ultraviolet rays with a low concentration of ultraviolet absorbers, thereby suppressing crystallization or exudation of ultraviolet absorbers, and realizing ultraviolet shielding properties necessary for suppressing deterioration of organic EL elements.

FIG. 1 is a cross-sectional view showing a layered structure of an organic EL display device according to an embodiment. The organic EL display device 901 includes a polarizing plate 10 on the light emitting surface of the organic EL unit 70 . A cover window 80 may be disposed on the viewing side surface of the polarizer 10 as needed.

The organic EL unit 70 may be either a top emission type or a bottom emission type. The organic EL unit of the top emission type is equipped with a metal electrode, an organic light-emitting layer, and a transparent electrode in sequence on a substrate, and is configured to extract light from the surface opposite to the substrate. The organic EL unit of the bottom emission type is provided with a transparent electrode, an organic light-emitting layer, and a metal electrode in sequence on a substrate, and is configured to extract light from the surface on the side of the substrate.

As the substrate of the organic EL unit, a glass substrate or a plastic substrate can be used. In a top emission type organic EL unit, 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-transporting layer, a hole-transporting layer, and the like in addition to the organic layer itself that functions as a light-emitting layer. The transparent electrode is a metal oxide layer or a metal thin film, allowing the light from the organic light-emitting layer to pass through.

The metal electrodes of the organic EL unit are light reflective. Therefore, when external light is incident on the inside of the organic EL cell, the light is reflected on the metal electrodes, and the reflected light is viewed from the outside like a mirror. By disposing a circular polarizing plate on the viewing side surface of the organic EL unit, it is possible to prevent the reflected light on the metal electrode from re-exiting to the outside, thereby improving the visibility and design of the screen.

[Structure of polarizing plate for organic EL display device] The circular polarizing plate 10 (polarizing plate for an organic EL display device) has a retardation layer 13 laminated on one surface (first main surface) of the polarizing element 11, and the surface on the retardation layer 13 side faces the organic EL unit 70 configured in the same way. The polarizing element 11 and the retardation layer 13 are preferably bonded via a suitable adhesive or adhesive. A suitable transparent protective film may also be disposed between the polarizing element 11 and the retardation layer 13 .

＜Polarizers＞ As the polarizing element 11, for example, a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene-vinyl acetate copolymer partially saponified film absorbs iodine or a dichroic film. Monoaxial stretching of dichroic substances such as dyes, polyene-based alignment films such as dehydrated polyvinyl alcohol or dehydrochlorinated polyvinyl chloride, etc.

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

＜Retardation Layer＞ When the retardation layer 13 has a front phase retardation of λ/4, and the angle between the slow axis direction of the retardation layer 13 and the absorption axis direction of the polarizing element 11 is 45°, the polarizing element 11 and the retardation layer 13 The polarizing plate, which is the laminated body, functions as a circular polarizing plate for suppressing re-emission of light reflected on the metal electrode of the organic EL unit 70 .

The retardation layer 13 may be a single layer or may include a plurality of layers. For example, by laminating the polarizing element 11, the λ/2 plate, and the λ/4 plate so that their respective optical axes form a specific angle, a wide band that functions as a circular polarizing plate within the wide band of visible light can be obtained. circular polarizer. Also, by laminating a retardation layer having a refractive index anisotropy of nx>nz>ny or nz>nx≧ny in addition to the λ/4 plate, the oblique direction (direction inclined from the normal direction) of the display device can be reduced. ) of reflected light.

In the present invention, at least one layer of the retardation layer 13 laminated on the first main surface side of the polarizing element 11 (hereinafter referred to as "first retardation layer") has a thickness greater than 5 μm and has ultraviolet shielding properties. For example, ultraviolet shielding properties can be imparted by making the first retardation layer contain an ultraviolet absorber. When the retardation layer 13 includes a plurality of layers, it is preferable that the layer with the largest thickness has ultraviolet shielding properties.

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

The first retardation layer is preferably transparent with little absorption of visible light, and the total light transmittance of the first retardation layer is preferably at least 80%, more preferably at least 85%, and still more preferably at least 90%. The light transmittance of the first retardation layer at a wavelength of 440 nm is preferably above 80%, more preferably above 85%, and even more preferably above 90%.

The thickness of the first retardation layer is preferably greater than 10 μm, more preferably greater than 15 μm, further preferably greater than 20 μm, and may be greater than 25 μm or greater than 30 μm. 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 or the thinning of the image display device, it is preferably 250 μm or less, and may be 200 μm or less, or 150 μm below or below 100 μm.

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

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 can be within the above-mentioned range, and high ultraviolet shielding properties can be imparted by adding a low-concentration ultraviolet absorber. Examples of non-liquid crystal resin materials include polycarbonate resins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyarylate resins, polyethylene, polyester, etc. Polymer resins such as ether resins, sulfide resins such as polyphenylene sulfide, polyimide resins, cyclic polyolefin (polynorthylene) resins, polyamide resins, polyethylene and polypropylene resins, etc. Olefin-based resins, cellulose esters, acrylic resins, styrene-based resins, maleimide-based resins, fumarate-based resins, etc.

(Ultraviolet Absorber) By containing an ultraviolet absorber in the first retardation layer, it is possible to impart ultraviolet absorptivity while maintaining transparency of visible light. Examples of the ultraviolet absorber include: benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers , trioxetin-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers. wait. In terms of high ultraviolet absorption and excellent compatibility with various polymers, trioxetin-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers are preferred, and trioxetin-based ultraviolet absorbers containing hydroxyl groups are preferred. Absorbers, and benzotriazole-based ultraviolet absorbers having one benzotriazole skeleton in one molecule.

A commercial item can also be used as a ultraviolet absorber. Commercially available trioxetine-based ultraviolet absorbers include: 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triquinone-2-yl)- The reaction product of 5-hydroxyphenyl and [(alkoxy)methyl]oxirane (“TINUVIN 400” manufactured by BASF), 2-(2,4-dihydroxyphenyl)-4,6- Reaction product of bis-(2,4-dimethylphenyl)-1,3,5-trimethanone and glycidic acid (2-ethylhexyl) ester ("TINUVIN 405" manufactured by BASF Corporation), (2 ,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-tributanol ("TINUVIN 460" manufactured by BASF Corporation) ), 2-(4,6-diphenyl-1,3,5-triphenyl-2-yl)-5-(hexyloxy)-phenol ("TINUVIN 577" manufactured by BASF Corporation), 2-( 2-Hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-trimethanone ("TINUVIN" manufactured by BASF Corporation) 479"), 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5 -Tinosorb ("Tinosorb S" manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triphenyl-2-yl)-5-[2-(2-ethylhexyl) oxy)ethoxy]-phenol ("ADK STAB LA-46" manufactured by ADEKA), 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1, 3,5-Three 𠯤 ("ADK STAB LA-F70" manufactured by ADEKA, etc.

Commercially available benzotriazole-based ultraviolet absorbers include: 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4 -(1,1,3,3-tetramethylbutyl)phenol (“TINUVIN 928” manufactured by BASF), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole ("TINUVIN PS" manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol ("TINUVIN PS" manufactured by BASF) 900"), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol ("TINUVIN 571" manufactured by BASF), 2-(2H-benzotriazole -2-yl) p-cresol ("TINUVIN P" manufactured by BASF, "ADK STAB LA-36G" manufactured by ADEKA), 2-(2H-benzotriazol-2-yl)-4-6-bis( 1-methyl-1-phenylethyl)phenol ("TINUVIN 234" manufactured by BASF), 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6- (Tertiary butyl)phenol (“TINUVIN 326” manufactured by BASF, “ADK STAB LA-36G” manufactured by ADEKA), 2-(2H-benzotriazol-2-yl)-4,6-ditertiary Amylphenol ("TINUVIN 328" manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol ("TINUVIN 328" manufactured by BASF) "TINUVIN 329"), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol ("ADK STAB LA-29" manufactured by ADEKA ), 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol] (manufactured by ADEKA "ADK STAB LA-31G"), phenylpropionic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyl (C7-9 side chain and linear alkyl) ester compound ("TINUVIN 384-2" manufactured by BASF), 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxy The reaction product of methyl phenyl)propionate and polyethylene glycol ("TINUVIN 1130" manufactured by BASF), 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl- The reaction product of methyl 4-hydroxyphenyl)propionate and polyethylene glycol 300 ("TINUVIN 213" manufactured by BASF), 2-[2-hydroxy-3-(3,4,5,6-tetrahydro-o- Phthalimido-methyl)-5-methylphenyl]benzotriazole ("Sumisorb 250" manufactured by Sumitomo Chemical) and the like.

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 when the concentration of the ultraviolet absorber is small, it is possible to have ultraviolet shielding properties necessary for suppressing deterioration of the organic EL element. Since there is no need to increase the concentration of the ultraviolet absorber, changes in surface properties or reduction in transparency due to precipitation or crystallization of the ultraviolet absorber are suppressed. From the viewpoint of improving ultraviolet shielding properties, the concentration of the ultraviolet absorber in the first retardation layer is preferably at least 0.01% by weight, more preferably at least 0.03% by weight, and may be at least 0.05% by weight, at least 0.07% by weight, or 0.1% by weight or more.

＜Protective Film for Polarizer＞ The polarizing plate 10 may also be laminated with a transparent film 12 serving as a protective film for the polarizing element on the surface (second main surface) on the viewing side of the polarizing element 11 through a suitable adhesive or adhesive. The transparent film 12 disposed on the viewing side of the polarizing element 11 is preferably transparent with little absorption of visible light. The total light transmittance of the transparent film 12 is preferably at least 80%, more preferably at least 85%, and still more preferably at least 90%. The light transmittance of the transparent film 12 at a wavelength of 440 nm is preferably above 80%, more preferably above 85%, and even more preferably above 90%.

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

The thickness of the transparent film 12 is not particularly limited, but it is preferably 5-250 μm, and may be 10-100 μm or 15-50 μm from the viewpoint of handleability and surface protection. A hard coat layer, an antireflection layer, an antisticking layer, etc. may also be provided on the surface of the transparent film 12 opposite to the polarizing element 11 (the surface on the viewing side).

The transparent film 12 disposed on the viewing side of the polarizing element 11 may have ultraviolet shielding properties, and may also contain an ultraviolet absorber. But on the other hand, it is difficult to have ultraviolet shielding properties for preventing deterioration of organic EL elements only by the transparent film 12. If the addition amount of ultraviolet absorbers is increased in order to improve ultraviolet shielding properties (ultraviolet absorbing properties), there will be When problems such as bleeding or crystallization of the ultraviolet absorber occur. The light transmittance of the transparent film 12 at a wavelength of 380 nm can also be 15-30%.

As described above, the retardation layer 13 of the polarizing plate 10 disposed on the side of the organic EL unit 70 of the polarizing element 11 has ultraviolet shielding properties. Therefore, even when the ultraviolet shielding properties of the transparent film 12 are not sufficient, the polarizing plate 10 can be provided with ultraviolet shielding properties capable of suppressing deterioration of the organic EL element (for example, the light transmittance at a wavelength of 380 nm is 4% or less. ).

The light transmittance of the polarizing plate 10 at a wavelength of 380 nm is preferably less than 4%, more preferably less than 3.5%, even more preferably less than 3%, and may be less than 2.5% or less than 2%. The light transmittance of the laminated body of the polarizing element 11 and the transparent film 12 (a single protective polarizing plate with the transparent film 12 layered on a single surface of the polarizing element 11) at a wavelength of 380 nm can also be 5 ~9%.

＜Adhesive layer＞ As mentioned above, the polarizing element 11 and the retardation layer 13, and the polarizing element 11 and the transparent film 12 are bonded together via appropriate adhesives or adhesives, respectively. The thickness of the adhesive layer is, for example, about 0.01 to 30 μm.

As the adhesive, various forms such as water-based adhesives, solvent-based adhesives, hot-melt adhesives, and active energy ray-curable adhesives can be used. Among them, a water-based adhesive or an active energy ray-curable adhesive is preferable in that the thickness of the adhesive layer can be reduced. When using an adhesive that exhibits adhesiveness by a hardening reaction after coating, the thickness of the adhesive layer is preferably 0.01 to 5 μm, more preferably 0.03 to 3 μm.

Examples of the polymer component of the water-based adhesive include vinyl polymers, gelatin, vinyl latex, polyurethane, polyester, epoxy, and the like. Among these, vinyl polymers are preferred, and polyvinyl alcohol-based resins are particularly preferred because the adhesiveness between the easily-adhesive film and the polarizing element is excellent. Among the polyvinyl alcohol-based resins, polyvinyl alcohol containing an acetoacetyl group is preferable.

Active energy ray hardening adhesives are adhesives that can undergo radical polymerization, cationic polymerization, or anionic polymerization by irradiation with active energy rays such as electron beams or ultraviolet rays. Among them, photoradical polymerizable adhesives, photocationically polymerizable adhesives, or photocationically polymerizable and photoradically polymerizable adhesives, which can be cured with low energy, are preferred. type adhesive.

As a monomer of a radically polymerizable adhesive agent, the compound which has a (meth)acryl group, or the compound which has a vinyl group is mentioned. Among them, a compound having a (meth)acryl group is suitable. As a hardening component of a cationic polymerizable adhesive agent, the compound which has an epoxy group or an oxetanyl group is mentioned. The compound which has an epoxy group will not be specifically limited if it has at least 2 epoxy groups in a molecule|numerator, Various well-known hardening epoxy compounds can be used normally.

Adhesives that use acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, fluorine-based or rubber-based polymers as base polymers can be appropriately selected. . In particular, an acrylic pressure-sensitive adhesive is preferable in terms of being excellent in optical transparency, exhibiting moderate wettability and aggregation property, and being excellent in weather resistance or heat resistance.

The thickness of the adhesive layer is preferably 1-30 μm, more preferably 2-25 μm. As mentioned above, since the first retardation film constituting the retardation layer 13 has ultraviolet absorbing properties, the adhesive layer used to bond the polarizing element 11 and the retardation layer 13 or the polarizing element 11 and the transparent film 12 does not need to have ultraviolet absorbing properties. sex. Therefore, it is not necessary to increase the thickness of the adhesive layer for the purpose of improving the ultraviolet shielding property, and it is possible to reduce the thickness of the adhesive layer. The thickness of the adhesive layer for attaching the polarizing element 11 and the retardation layer 13 or the polarizing element 11 and the transparent film 12 may also be less than 15 μm, less than 10 μm or less than 7 μm.

Among the optical layers constituting the polarizing plate 10, the above-mentioned first retardation layer may be the layer with the largest thickness. The optical layer constituting the polarizing plate 10 includes a polarizing element 11, a transparent film 12, one or more than two optical layers (including the first retardation layer) constituting the retardation layer 13, and a film for laminating these layers. Adhesive layer. Among them, by making the first retardation layer having the largest thickness contain an ultraviolet absorber, a high ultraviolet shielding property can be imparted with a low concentration of ultraviolet absorber, so bleeding or crystallization of the ultraviolet absorber can be suppressed, and the The polarizing plate 10 has ultraviolet shielding properties required to suppress deterioration of organic EL elements.

An adhesive layer 21 for bonding with transparent components such as the cover window 80 may also be provided on the viewing side surface of the polarizing plate 10 . An adhesive layer 22 for bonding with the organic EL unit may also be provided on the surface of the polarizing plate 10 on the side of the organic EL unit 70 . The thickness of these adhesive layers is usually about 5-300 μm.

On the surface of the adhesive layer 21, 22, a release film may be temporarily adhered for the purpose of preventing contamination of the adhesive layer or the like. As the separator, the surface of the plastic film is preferably 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.

[Concrete example of the composition of the retardation layer] As described above, the polarizing plate 10 for an organic EL display device functions as a circular polarizing plate by including the retardation layer 13 on one surface of the polarizing element 11, and suppresses the reappearance of reflected light caused by the metal electrodes of the organic EL unit 70, etc. shoot. In addition, the retardation layer 13 includes one or more optical layers, at least one of which (the first retardation layer) has ultraviolet shielding properties, and thus also contributes to suppressing deterioration of the organic EL element. Hereinafter, a specific example of the configuration of the retardation layer 13 of the polarizing plate 10 will be described.

The polarizing plate 102 shown in FIG. 2 has a configuration in which the retardation layer 13 includes one retardation layer 131 . The phase difference layer 131 is a λ/4 plate, and the front phase retardation R(550) at a wavelength of 550 nm is preferably 100-180 nm, more preferably 110-170 nm, and further preferably 120-150 nm. 125~145nm.

The angle formed by the direction of the slow axis of the retardation layer 131 and the direction of the absorption axis of the polarizer 11 is 10-90°, preferably 40-50°, or 43-47° or 44-46°. The retardation layer 131 is a λ/4 plate. If the angle between the slow axis direction of the retardation layer 131 and the absorption axis direction of the polarizer 11 is around 45°, the polarizer 102 functions as a circular polarizer.

The phase difference layer 131 as a λ/4 plate can also be one whose front phase retardation R (450) at a wavelength of 450 nm is smaller than that of the front phase retardation R (550) at a wavelength of 550 nm. In addition to R(450)<R(550), the λ/4 plate can also have front phase retardation R(650) greater than R(550) at a wavelength of 650 nm, satisfying R(550)<R(650). By using a λ/4 plate having a large phase retardation of about a long wavelength, the circular polarizing plate 10 functions as a circular polarizing plate in a wide wavelength region of visible light, thereby reducing coloring of reflected light.

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

The retardation layer 131 is preferably a stretched film. The retardation layer 131 as a stretched film can be obtained by stretching the resin film in a specific direction and imparting an optical anisotropy in which the front retardation R(550) is in the above-mentioned range. The stretching method is not particularly limited, and free-end uniaxial stretching using a roll stretching machine may be used. It is also possible to attach a heat-shrinkable film on one or both sides of the resin film, and use the shrinkage of the heat-shrinkable film at the same time as the stretching, so that the film is excessively shrunk in the direction (width direction) perpendicular to the stretching direction to increase the thickness. way to extend. As the stretching method, horizontal stretching using a tenter stretching machine, vertical and horizontal biaxial stretching, or diagonal stretching can also be used.

When the resin material constituting the resin film is a material with positive intrinsic birefringence, a retardation layer (positive A plate) with a refractive index anisotropy of nx>ny≒nz can be obtained by uniaxially extending the free end . nx is the refractive index in the direction of the slow axis in the plane, ny is the refractive index in the direction of the fast axis in the plane, and nz is the refractive index in the thickness direction.

If stretching is performed while excessively shrinking in the width direction by using the shrinkage force of the heat-shrinkable film, the refractive index nz in the thickness direction becomes larger than the refractive index ny in the width direction (fast axis direction), so nx>nz can be obtained. >ny retardation layer with refractive index anisotropy. Since the retardation layer with a refractive index anisotropy of nx>nz>ny has a small change in phase retardation caused by the viewing angle, if a λ/4 plate with a refractive index anisotropy of nx>nz>ny is used as The retardation layer 131 can not only reduce the reflected light from the front (normal direction) of the display device, but also reduce the reflected light from the oblique direction.

As mentioned above, in the polarizing plate 102, the polarizing element 11 and the phase difference layer 131 are based on the fact that the optical axes of the two become neither parallel nor perpendicular directions (for example, the angle formed by the absorption axis direction and the slow axis direction is 45°. °) stacked layers. In order to obtain a circular polarizing plate by laminating the polarizing element and the retardation layer in a roll-to-roll manner, it is preferable to use an obliquely stretched film as the retardation layer 13 . For example, a diagonally stretched film obtained by stretching a direction at 45° with respect to the longitudinal direction (transportation direction) as the slow axis direction, and a polarizer having an absorption axis in the longitudinal direction are laminated in a roll-to-roll manner , can make long circular polarizing plates, so it can greatly improve production efficiency and yield. The obliquely stretched film generally has a refractive index anisotropy of nx>ny>nz.

FIG. 3 is another example of the configuration of a polarizing plate for an organic EL display device. The retardation layer 13 of the polarizing plate 103 includes two layers of 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 of FIG. 2 . The retardation layer 133 has a refractive index anisotropy of nz>nx≧ny.

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, due to the phase difference layer 133 to offset the phase difference in the oblique direction of the phase difference layer 131, so the phase difference layer 13, which is a laminate of the phase difference layer 131 and the phase difference layer 133, has the refractive index anisotropy of nx>nz>ny, from the viewing angle The resulting change in phase delay is small, so not only can the reflected light from the front of the display device be reduced, but also the reflected light from oblique directions can be reduced.

As a positive C plate having a refractive index anisotropy of nz>nx≒ny, for example: a vertical alignment liquid crystal layer that aligns liquid crystal molecules in the normal direction (thickness direction) of the retardation layer, and a negative intrinsic birefringence A coating film in which polymers are coated and aligned in-plane, a stretched film obtained by biaxially stretching a film of a polymer having negative intrinsic birefringence so that the front phase retardation becomes substantially zero, and the like. nx≒ny is not limited to the case where nx and ny are exactly the same, and the front phase retardation R(550) is only 10 nm or less. The front phase retardation R(550) of the positive C plate is preferably less than 5 nm, and may be less than 3 nm or less than 1 nm.

The retardation layer 13 is a retardation layer (λ/4 plate) 131 having a refractive index anisotropy of nx>ny≧nz and a retardation layer (positive C plate) having a refractive index anisotropy of nz>nx≒ny ) 133, as long as either one of the retardation layer 131 and the retardation layer 133 is a first retardation layer having ultraviolet shielding properties. In the case of imparting ultraviolet shielding properties by including an ultraviolet absorber, it is preferable that the relatively thick retardation layer contains an ultraviolet absorber and has a light transmittance of 60% or less at a wavelength of 380 nm.

For example, when the phase difference layer 131 is a stretched film, and the phase difference layer 133 is a positive C plate including an alignment liquid crystal layer, the thickness of the stretched film is usually greater than the thickness of the liquid crystal layer, so it is preferable to have a relatively large thickness. The layer 131 is the first retardation layer, and the light transmittance at a wavelength of 380 nm is 60% or less, and the retardation layer 133 (second retardation layer) of nz>nx≒ny may not have ultraviolet shielding properties.

In the case where both of the retardation layer 131 and the retardation layer 133 are polymer films comprising a non-liquid crystalline resin material, it is sufficient that either of the retardation layer 131 and the retardation layer 133 has an ultraviolet shielding property. Preferably, the retardation layer with a relatively large thickness has ultraviolet shielding properties and a light transmittance of 60% or less at a wavelength of 380 nm. For example, when the thickness of the retardation layer 131 is less than the thickness of the retardation layer 133, it is preferable that the retardation layer 131 as the λ/4 plate is the first retardation layer with ultraviolet shielding properties, and the second retardation layer as the positive C plate. The two retardation layers 133 may not have ultraviolet shielding properties. Both the retardation layer 131 and the retardation layer 133 may have ultraviolet shielding properties.

In FIG. 3 , the diagram shows that the phase difference layer 133 as a positive C plate is disposed on the surface opposite to the polarizing element 11 of the retardation layer 131 as a λ/4 plate, but it can also be used on the polarizing element 11 and the polarizing element 11. A retardation layer 133 is disposed between the retardation layers 131 .

FIG. 4 is yet another example of the configuration of a polarizing plate for an organic EL display device. The retardation layer 13 of the polarizing plate 104 includes 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 of FIG. 2 . The retardation layer 135 has a refractive index anisotropy of nx>nz>ny.

The retardation layer 135 having a refractive index anisotropy of nx>nz>ny, like the retardation layer 133 in the above-mentioned polarizing plate 103, can have the effect of canceling the retardation in the oblique direction of the retardation layer 131. Also, by disposing the slow axis direction of the retardation layer 135 parallel to or perpendicular to the absorption axis direction of the polarizing element 11, the retardation layer 135 can compensate for the apparent appearance of the polarizing element 11 when viewed from an oblique direction. The effect of the offset of the optical axis direction.

The angle formed by the direction of the slow axis of the retardation layer 135 and the direction of the absorption axis of the polarizer 11 is preferably 0°-5° or 85°-90°, more preferably 0°-3° or 87°-90°, More preferably, it is 0° to 1° or 89° to 90°.

The NZ coefficient defined by NZ=(nx−nz)/(nx−ny) of the retardation layer 135 is greater than 0 and less than 1. The NZ coefficient of the retardation layer 135 is preferably 0.1-0.9, more preferably 0.2-0.8, further preferably 0.3-0.7, or 0.4-0.6 or 0.45-0.55.

The front retardation R(550) of the retardation layer 135 at a wavelength of 550 nm is, for example, 100-400 nm. The R(550) of the retardation layer 135 can also be 200-350 nm, 220-330 nm, 240-310 nm, 250-300 nm or 260-290 nm.

The retardation layer 13 is composed of a laminate 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 In this case, as long as either one of the retardation layer 131 and the retardation layer 135 is the first retardation layer having ultraviolet shielding properties, both of the retardation layer 131 and the retardation layer 135 may have ultraviolet shielding properties. sex.

The composition of the retardation layer 13 in the polarizing plate for an organic EL display device of the present invention is not limited to the embodiments shown in FIGS. The light transmittance under nm is 60% or less. The retardation layer 13 may also be composed of a laminate of three or more retardation layers.

[Organic EL display 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 exit surface of the organic EL unit 70 . A touch panel (not shown) may also be arranged between the organic EL unit 70 and the polarizer 10 .

The cover window 80 may also be arranged on the polarizing plate 10 for the purpose of preventing breakage of the organic EL unit 7 due to an impact from the outer surface. As the cover window 80, a transparent plate having suitable mechanical strength and thickness can be used. As such a transparent plate, a transparent resin plate such as acrylic resin, polycarbonate resin, transparent polyimide resin, or a glass plate can be used. The thickness of the cover window 80 is, for example, about 20 to 2000 μm. The cover window 80 can also be integrated with the touch panel sensor. An anti-reflection layer or a hard coating may also be provided on the viewing side surface of the cover window 80 .

As described above, it is preferable to use the adhesive layers 21 and 22 for bonding the polarizing plate 10 and the organic EL unit 70 , and for bonding the polarizing plate 10 and the cover window 80 . In the present invention, since the polarizing plate 10 has ultraviolet shielding properties, even when the adhesive layers 21 and 22 do not contain ultraviolet absorbers, the incident amount of ultraviolet rays contained in external light to the organic EL unit 70 is reduced, Therefore, deterioration of the organic EL element can be suppressed. [Example]

Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated in more detail, this invention is not limited to these examples.

[Manufacturing example of adhesive sheet] ＜Adhesive Sheet A＞ As a monomer, butyl acrylate: 92 parts by weight, N-acrylyl methionine (ACMO): 5 parts by weight, acrylic acid: 2.9 parts by weight, and 2-hydroxyethyl acrylate: 0.1 parts by weight, and as a polymerizer 2,2'-Azobisisobutyronitrile: 0.1 part by weight of the starting agent was added into the reaction vessel together with ethyl acetate, and reacted at 55° C. for 8 hours under nitrogen flow. Thereafter, ethyl acetate was added to the reaction liquid to obtain a solution of an acrylic polymer having a weight average molecular weight of 1,780,000. In this solution, 0.15 parts by weight of dibenzoyl peroxide ("Nyper BMT" manufactured by NOF Corporation) as a crosslinking agent, and trimethylolpropane/toluene diisocyanate plus Finished product ("Coronate L" manufactured by Tosoh): 0.6 parts by weight to obtain an adhesive composition.

Apply the above adhesive composition on the release surface of the release film (polyethylene terephthalate film treated with silicone release), dry and cross-link at 150°C to make the thickness Adhesive sheet of 5 μm.

＜Adhesive sheet B＞ In the preparation of the adhesive composition, in addition to the crosslinking agent, a UV absorber (5,5'-bis(2-ethylhexyloxy)-2,2'-[6-( 4-methoxyphenyl)-1,3,5-tris(2,4-diyl]diphenol, "Tinosorb S" manufactured by BASF): 6 parts by weight. Except for this, an adhesive sheet having a thickness of 5 μm was obtained in the same manner as in the preparation of the adhesive sheet A.

＜Adhesive Sheet C＞ In the preparation of the adhesive composition, the compounding 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. Except for this, an adhesive sheet having a thickness of 40 μm was obtained in the same manner as in the preparation of the adhesive sheet B.

[Manufacturing example of retardation film] ＜Retardation Film A＞ (Preparation of polycarbonate (PC) resin) Put bis[9-(2-phenoxycarbonylethyl)-9-yl]methane into the reaction vessel: 38.06 parts by weight, isosorbide ("POLYSORB" manufactured by Roquette Freres): 53.73 parts by weight, 1, 4-cyclohexanedimethanol (cis-trans mixture, manufactured by SK Chemical): 9.64 parts by weight, and diphenyl carbonate (manufactured by Mitsubishi Chemical): 81.28 parts by weight, and calcium acetate monohydrate as a catalyst, under reduced pressure After nitrogen substitution, the mixture was stirred at 150° C. for about 10 minutes under a nitrogen stream to dissolve the raw material. After the temperature was raised to 220° C., the reaction was carried out under normal pressure for 60 minutes. Thereafter, the pressure was reduced from normal pressure to 13.3 kPa and maintained for 30 minutes, and the produced phenol was discharged out of the reaction system. Then, while raising the temperature to 240° C., the pressure was reduced to 0.10 kPa or less, and the generated phenol was discharged out of the reaction system. After reaching the specified stirring torque, the pressure was restored to normal pressure with nitrogen and the reaction was stopped. The resulting polycarbonate was extruded into water, and the strands were cut to obtain polycarbonate (PC) resin pellets.

(Making of Stretch Film) Using the above-mentioned polycarbonate resin pellets, an unstretched film having a thickness of 100 μm was produced by a melt extrusion method. The film was stretched obliquely at a temperature of 137°C and a stretching ratio of about 2.5 times by a tenter stretching machine capable of independently controlling the traveling speed of the left and right clamps, so that the direction of the slow axis was 45° relative to the length of the film The stretched retardation film.

＜Retardation Film B＞ In the preparation of the polycarbonate resin, a trioxane-based ultraviolet absorber (2,4,6-tris(2-hydroxy-4-hexyloxy-3 -Methylphenyl)-1,3,5-trimethanone, "Adekastab LA-F70" manufactured by ADEKA): 0.2 parts by weight to obtain polycarbonate resin particles containing an ultraviolet absorber. A stretched retardation film was produced in the same manner as the production of the retardation film A except for using the particles.

<Retardation film C, D> In the preparation of polycarbonate resin, the compounding quantity of the ultraviolet absorber (Adekastab LA-F70) was changed to 0.3 weight part (retardation film C), and 1.0 weight part (retardation film D). Except for this, the stretched retardation film was produced in the same manner as the preparation of the retardation film B.

<Retardation film E, F> In the preparation of polycarbonate resin, the type of UV absorber was changed to 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-(1,1,3 , 3-tetramethylbutyl) phenol], and the compounding amount was set to 0.7 parts by weight (retardation film E) and 0.9 parts by weight (retardation film F). Except for this, the stretched retardation film was produced in the same manner as the preparation of the retardation film B.

＜Retardation Film G＞ In the preparation of polycarbonate resin, the blending amount of ultraviolet absorber (Adekastab LA-F70) was changed to 0.05 parts by weight to make polycarbonate resin pellets, and a 235 μm thickness was made by melt extrusion. Stretch film. A biaxially stretched polypropylene film ("Torayfan" manufactured by Toray) laminated with an adhesive sheet was bonded to both sides of the film. The free end of the laminate was uniaxially stretched about 1.5 times in the longitudinal direction at a temperature of 145° C. by a roll stretcher. Thereafter, the biaxially stretched acrylic film on both surfaces was peeled off to obtain a stretched retardation film in which the refractive index nz in the thickness direction was larger than the refractive index ny in the width direction (fast axis direction).

＜Stretched Film H＞ Dissolve cyclic olefin polymer (COP) resin particles ("ARTON R5000" manufactured by JSR): 100 parts by weight, and ultraviolet absorber (Adekastab LA-F70): 0.05 parts by weight in methylene chloride, and pass through the solution An unstretched film with a thickness of 130 μm was produced by the film-forming method. A biaxially stretched polypropylene film ("Torayfan" manufactured by Toray) with an adhesive sheet laminated on both sides of the film was stretched uniaxially at the free end in the longitudinal direction at a temperature of 140°C by a roll stretching machine. After 1.3 times, the biaxially stretched acrylic film on both sides was 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.

＜Retardation Film I＞ (Preparation of fumarate (FAE) resin) Hydroxypropyl methylcellulose ("Metolose 60SH-50" manufactured by Shin-Etsu Chemical Co., Ltd.): 48 parts by weight, distilled water: 15600 parts by weight, diisopropyl fumarate: 8161 parts by weight, acrylic acid 3 -Ethyl-3-oxetanyl methyl ester: 240 parts by weight, and tert-butyl peroxypivalate as a polymerization initiator, after blowing nitrogen gas for 1 hour, keep stirring at 49°C for 24 hours , while performing free radical suspension polymerization. Then, after cooling to room temperature, the suspension containing the generated 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-based resin.

(film production) A resin solution was prepared by dissolving the above-mentioned fumarate-based resin in a mixed solvent of toluene/methyl ethyl ketone, and an unstretched film (coated retardation film) with a thickness of 6 μm was produced by a solution film-forming method.

＜Retardation Film J＞ In preparation of the film, an ultraviolet absorber (Adekastab LA-F70): 0.9 parts by weight was added to 100 parts by weight of the fumarate resin to prepare a solution. Except for this, the coating retardation film was produced in the same manner as preparation of the retardation film J.

[Evaluation of Adhesive Sheet and Retardation Film] ＜Precipitation and crystallization of ultraviolet absorbers＞ Cut the sample to a size of 200 mm×300 mm, keep it in a constant temperature and humidity chamber at a temperature of 20°C and a relative humidity of 98% for 500 hours, then take it out, and observe it with a microscope to confirm whether there is precipitation or crystallization of the ultraviolet absorber change.

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

＜Phase delay＞ Retardation films A~J were cut out to a size of 50 mm×50 mm, and the front phase retardation was measured at a measurement wavelength of 550 nm by a polarization-retardation measurement system ("AxoScan" manufactured by Axometrics), and the slow axis direction Phase delay when the sample is tilted by 40° as the center of rotation. From these measured values, front phase retardation Re=(nx-ny)×d and thickness direction retardation Rth=(nx-nz)×d at a wavelength of 550 nm were calculated. nx is the refractive index in the direction of the slow axis in the plane, ny is the refractive index in the direction of the fast axis in the plane, nz is the refractive index in the thickness direction, and d is the thickness of the retardation film. The calculation of the phase retardation in the thickness direction used the average refractive index measured with an Abbe refractometer manufactured by Atago Corporation.

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

[Table 1] resin UVA Thickness (μm) 380 nm transmittance (%) Precipitation and crystallization phase delay type Amount added (parts by weight) Re (nm) Rth (nm) Adhesive sheet A acrylic resin - 5 96 - - B acrylic resin Tinosorb S 6.0 5 45 have - C acrylic resin Tinosorb S 0.8 40 45 have - Retardation film A PC - 37 95 - 120 155 B PC LA-F70 0.2 37 39 none 133 164 C PC LA-F70 0.3 37 25 none 134 165 D. PC LA-F70 1.0 37 2 none 135 170 E. PC LA-31G 0.7 37 51 none 122 152 f PC LA-31G 0.9 37 42 none 125 157 G COP LA-F70 0.05 250 twenty one none 130 65 h COP LA-F70 0.05 135 20 none 270 135 I FAE - 6 94 - 0 -110 J FAE LA-F70 0.9 6 51 none 0 -110

[Production of Circular Polarizer] ＜Production of single protective polarizer＞ (Production of Polarizer) Corona treatment is performed on one side of an amorphous polyester film (polyethylene-terephthalate/isophthalate, glass transition temperature 75°C) with a thickness of 100 μm. The weight ratio of 9:1 contains polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mole%) and acetoacetyl-modified polyvinyl alcohol (Nippon Synthetic Chemical Industry "GOHSEFIMER Z200", polymerization degree 1200, acetylene Acetyl modification degree of 4.6%, saponification degree of 99.0 mole% or more) aqueous solution is coated and dried at 25°C, and a PVA (Polyvinyl Alcohol, polyvinyl alcohol) is a laminate of resin layers.

The free end of the laminate was uniaxially stretched 2.0 times in the longitudinal direction in an oven at 120°C. The stretched laminate was immersed in 4% boric acid aqueous solution at 30°C for 30 seconds, and then immersed in dyeing solution (0.2% iodine, 1.0% potassium iodide aqueous solution) at 30°C for 60 seconds. Then, it immersed in the crosslinking liquid (3% of potassium iodide, 3% of boric acid aqueous solution) for 30 seconds at 30 degreeC, and performed the crosslinking process. Thereafter, while immersing the laminate in a 70°C aqueous solution of 4% boric acid and 5% potassium iodide, the free end was uniaxially stretched in the longitudinal direction so that the total stretching ratio became 5.5 times. Thereafter, the laminate was immersed in a cleaning solution (4% potassium iodide aqueous solution) at 30° C. to obtain a laminate in which a PVA-based polarizing element with a thickness of 5 μm was provided on an amorphous polyester film substrate.

(Lamination of protective film for polarizing element) 40 parts by weight of N-hydroxyethylacrylamide (HEAA) and 60 parts by weight of acryloyl methionine (ACMO) were mixed with a photopolymerization initiator ("Irgacure 819" manufactured by BASF) ) 3 parts by weight were mixed to prepare an ultraviolet curable adhesive. Apply the adhesive to the surface of the polarizing element of the above-mentioned laminate with a thickness of about 1 μm, attach a triacetyl cellulose (TAC) film with a thickness of 25 μm on it as a protective film for the polarizing element, and irradiate the cumulative irradiation dose 1000/mJ/cm ² of ultraviolet light to harden the adhesive. Thereafter, the amorphous polyester film substrate was peeled off to obtain a single protective polarizing plate in which a TAC film was bonded to one side of a thin polarizing element with a thickness of about 5 μm via an adhesive. The light transmittance of the single protective polarizer at a wavelength of 380 nm is 6.6%.

＜Comparative example 1＞ Using a roller laminating machine, the retardation film A was bonded to the surface of the polarizing element side of the single protection polarizing plate through the adhesive sheet A to produce a circular polarizing plate. The angle formed by the absorption axis of the polarizer and the slow axis (extension direction) of the retardation film is 45°.

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

<Example 6> The single protective polarizer and the retardation film G are cut out into rectangles, and the retardation film G is pasted on the surface of the single protective polarizer on the polarizer side through the adhesive sheet A to produce a circular polarizer. The angle formed by the absorption axis of the polarizer and the slow axis (extension direction) of the retardation film is 45°.

<Example 7> Using a roller laminating machine, the retardation film H is pasted on the surface of the polarizing element side of the single protection polarizing plate through the adhesive sheet A, and the retardation film A is pasted on the retardation film H through the adhesive sheet A to make a circle. polarizer. The absorption axis of the polarizer is parallel to the slow axis (extension direction) of the retardation film H, and the angle formed between the absorption axis of the polarizer and the slow axis of the retardation film A is 45°.

<Example 8> Using a roller laminating machine, the retardation film H is pasted on the surface of the polarizing element side of the single protection polarizing plate through the adhesive sheet A, and the retardation film A is pasted on the retardation film H through the adhesive sheet A to make a circle. polarizer. The absorption axis of the polarizer is parallel to the slow axis (extension direction) of the retardation film H, and the angle formed between the absorption axis of the polarizer and the slow axis of the retardation film A is 45°.

<Example 9, 10> Except having changed the kind of retardation film as shown in Table 2, it carried out similarly to Example 8, and produced the circular polarizing plate provided with two layers of retardation films on one surface of a polarizing element.

Table 2 shows the laminated structures of the circular polarizing plates of Examples and Comparative Examples, and the light transmittance of the circular polarizing plates at a wavelength of 380 nm.

[Table 2] Laminated composition Polarizer 380 nm transmittance (%) Adhesive sheet Retardation film 1 Retardation film 2 type Thickness (μm) 380 nm transmittance (%) type Thickness (μm) 380 nm transmittance (%) type Thickness (μm) 380 nm transmittance (%) Comparative example 1 A 5 96 A 37 95 - 6.0 Example 1 A 5 96 B 37 39 - 2.5 Example 2 A 5 96 C 37 25 - 1.6 Example 3 A 5 96 D. 37 2 - 0.1 Example 4 A 5 96 E. 37 51 - 3.2 Example 5 A 5 96 f 37 42 - 2.6 Comparative example 2 B 5 45 A 37 95 - 2.8 Comparative example 3 C 40 45 A 37 95 - 2.8 Example 6 A 5 96 G 250 twenty one - 1.3 Example 7 A 5 96 h 135 20 A 37 95 1.2 Example 8 A 5 96 A 37 95 J 6 51 3.2 Example 9 A 5 96 B 37 39 J 6 51 1.3 Example 10 A 5 96 B 37 39 I 6 94 2.4

As shown in Table 1, when a UV absorber is mixed with an adhesive constituting an adhesive sheet, precipitation and crystallization of the UV absorber occur in a high-humidity environment. In the case of the absorber, precipitation and crystallization of the ultraviolet absorber were not observed, and it had a good appearance.

By including the ultraviolet absorber in the retardation film, the ultraviolet shielding properties equal to or higher than those in the case of including the ultraviolet absorber in the adhesive sheet (Comparative Examples 2 and 3) can be imparted without crystallization or precipitation of the ultraviolet absorber. It can be seen that since the thickness of the retardation film is large, even a low concentration of 1% or less of the ultraviolet absorber exhibits excellent ultraviolet shielding properties.

10: polarizer (circular polarizer) 11: Polarizing element 12: Transparent film (polarizer protective film) 13: Retardation layer 21: Adhesive layer 22: Adhesive layer 70: Organic EL unit 80: Overlay window 102: polarizer (circular polarizer) 103: polarizer (circular polarizer) 104: polarizer (circular polarizer) 131: Retardation layer (λ/4 plate) 133: Retardation layer 135: Retardation layer 901: Organic EL display device

FIG. 1 is a cross-sectional view showing a layered structure of an organic EL display device according to an embodiment. Fig. 2 is a cross-sectional view showing a laminated structure of a polarizing plate according to an embodiment. Fig. 3 is a cross-sectional view showing a laminated structure of a polarizing plate according to an embodiment. Fig. 4 is a cross-sectional view showing a laminated structure of a polarizing plate according to an embodiment.

10: polarizer (circular polarizer)

11: Polarizing element

12: Transparent film (polarizer protective film)

13: Retardation layer

21: Adhesive layer

22: Adhesive layer

70: Organic EL unit

80: Overlay window

901: Organic EL display device

Claims (18)

A polarizing plate for an organic EL display device, comprising a polarizing element having a first main surface and a second main surface, and a first retardation layer laminated on the first main surface side of the above-mentioned polarizing element, and using the above-mentioned polarizing element The first main surface side is arranged in such a way that it faces the organic EL unit, The thickness of the first retardation layer is greater than 5 μm, and the light transmittance at a wavelength of 380 nm is less than 60%. As the polarizing plate for organic EL display device of claim 1, the light transmittance at a wavelength of 380 nm is 4% or less. The polarizing plate for an organic EL display device according to claim 1 or 2, wherein the first retardation layer contains an ultraviolet absorber. The polarizing plate for an organic EL display device according to claim 3, wherein the concentration of the ultraviolet absorber contained in the first retardation layer is 0.01 to 1.5% by weight. The polarizing plate for an organic EL display device according to claim 1 or 2, wherein the angle formed by the slow axis direction of the first retardation layer and the absorption axis direction of the polarizing element is 10° to 80°. The polarizing plate for an organic EL display according to claim 1 or 2, wherein the angle formed by the slow axis direction of the first retardation layer and the absorption axis direction of the polarizing element is 40° to 50°. The polarizing plate for an organic EL display device according to claim 1 or 2, wherein the front phase retardation R(550) of the first retardation layer at a wavelength of 550 nm is 100-180 nm. The polarizing plate for an organic EL display device according to claim 1 or 2, wherein the front phase retardation R (450) of the first phase difference layer at a wavelength of 450 nm is smaller than the front phase retardation R (550) at a wavelength of 550 nm. The polarizing plate for an organic EL display device according to claim 1 or 2, wherein the first retardation layer is a stretched film. The polarizing plate for an organic EL display device according to claim 1 or 2, wherein the first retardation layer is an obliquely stretched film. The polarizing plate for an organic EL display device according to claim 1 or 2, which has a second polarizer between the polarizing element and the first retardation layer, or on the surface of the first retardation layer opposite to the polarizing element. phase difference layer. The polarizing plate for an organic EL display device according to claim 11, wherein the second retardation layer has a refractive index nx in the direction of the slow axis in the plane, a refractive index ny in the direction of the fast axis in the plane, and a refractive index nz in the thickness direction Satisfy nz>nx≧ny. The polarizing plate for an organic EL display device according to claim 1 or 2, further comprising a transparent film laminated on the second main surface side of the polarizing element. A polarizing plate for an organic EL display device according to claim 13, wherein the light transmittance of the transparent film at a wavelength of 380 nm is 15-30%. The polarizing plate for an organic EL display device according to claim 13, wherein the transparent film is a cellulose-based resin film. The polarizing plate for an organic EL display device according to claim 13, wherein the light transmittance of the laminate of the above-mentioned polarizing element and the above-mentioned transparent film at a wavelength of 380 nm is 5-9%. The polarizing plate for an organic EL display device according to claim 1 or 2, wherein the first retardation layer has the largest thickness among the optical layers constituting the polarizing plate. An organic EL display device comprising an organic EL unit and a polarizing plate disposed on the light emitting surface side of the organic EL unit, wherein the polarizing plate is the polarizing plate according to any one of claims 1 to 17.

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