JP2015106114A - Circular polarization plate for organic el display device, and organic el display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing plate for an organic EL display device, which exhibits superior anti-reflection function both in frontal and oblique directions.SOLUTION: A circular polarization plate of the present invention is used for organic EL display devices. The circular polarization plate includes: a polarizer; a first retardation layer that functions as a λ/2 plate; a second retardation layer that functions as a λ/4 plate; and a third retardation layer having an index ellipsoid that satisfies nz>nx≥ny. An angle α (°) between an absorption axis of the polarizer and a slow axis of the first retardation layer, and an angle β (°) between the slow axis of the first retardation layer and a slow axis of the second retardation axis satisfy an expression (1a) or (1b): α+35°<β<α+55° (0°≤α≤90°)...(1a), α-35°<β<α-55° (90°<α<180°)...(1b).

Description

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

  In recent years, with the spread of thin displays, displays equipped with organic EL panels have been proposed. Since the organic EL panel has a highly reflective metal layer, problems such as external light reflection and background reflection tend to occur. Thus, it is known to prevent these problems by providing a circularly polarizing plate on the viewing side. As a general circularly polarizing plate, a laminate of a polarizer, a λ / 2 plate, and a λ / 4 plate is known (for example, Patent Documents 1 and 2). However, such a circularly polarizing plate has an excellent antireflection function for external light from the front and near the front, but is insufficient in antireflection function for external light from an oblique direction. There's a problem.

  In addition, a circularly polarizing plate including a retardation film having a so-called reverse dispersion wavelength dependency (reverse dispersion wavelength characteristic) in which a retardation value increases according to the wavelength of measurement light has been proposed (for example, Patent Document 3). . However, such a circularly polarizing plate has an insufficient antireflection function on the front surface as compared with the circularly polarizing plate including the λ / 2 plate and the λ / 4 plate as described above.

JP 2003-311239 A JP 2002-372622 A Japanese Patent No. 3325560

  The present invention has been made to solve the above-described conventional problems, and its main object is to provide a circularly polarizing plate for an organic EL display device having an excellent antireflection function in both the front direction and the oblique direction. There is.

The circularly polarizing plate of the present invention is used for an organic EL display device. This circularly polarizing plate includes a polarizer, a first retardation layer that functions as a λ / 2 plate, a second retardation layer that functions as a λ / 4 plate, and a refractive index ellipsoid of nz> nx ≧ ny. An angle formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is α (°), and the retardation of the first retardation layer is When the angle formed by the phase axis and the slow axis of the second retardation layer is β (°), the angles α and β satisfy the following formula (1a) or (1b):
α + 35 ° <β <α + 55 ° (0 ° ≦ α ≦ 90 °) (1a)
α-35 ° <β <α-55 ° (90 ° <α <180 °) (1b).
In one embodiment, the circularly polarizing plate includes the polarizer, the first retardation layer, the third retardation layer, and the second retardation layer in this order.
In one embodiment, the circularly polarizing plate further includes a fourth retardation layer having a refractive index ellipsoid of nz> nx ≧ ny. For example, the circularly polarizing plate includes the polarizer, the fourth retardation layer, the first retardation layer, the third retardation layer, and the second retardation layer in this order. Alternatively, the circularly polarizing plate includes the polarizer, the first retardation layer, the third retardation layer, the second retardation layer, and the fourth retardation layer in this order. Alternatively, the circularly polarizing plate includes the polarizer, the third retardation layer, the first retardation layer, the second retardation layer, and the fourth retardation layer in this order.
In one embodiment, at least one of the third retardation layer and the fourth retardation layer has a refractive index ellipsoid of nz>nx> ny.
In one embodiment, the angle α satisfies the following formula (2):
5 ° ≦ α ≦ 85 ° or 95 ° ≦ α ≦ 175 ° (2).
According to another aspect of the present invention, an organic EL display device is provided. This organic display device includes the circularly polarizing plate described above.

  According to the present invention, in the circularly polarizing plate used in the organic EL display device, the slow axis of the first retardation layer functioning as the λ / 2 plate is set at a predetermined angle with respect to the absorption axis of the polarizer. And setting the slow axis and the slow axis of the second retardation layer functioning as a λ / 4 plate to form a predetermined angle, and having a refractive index ellipsoid of nz> nx ≧ ny By further providing the third retardation layer, a circularly polarizing plate for an organic EL display device having an excellent antireflection function in both the front direction and the oblique direction can be obtained.

It is a schematic sectional drawing of the circularly-polarizing plate by one Embodiment of this invention. It is a schematic sectional drawing of the circularly-polarizing plate by another embodiment of this invention. It is a schematic sectional drawing of the circularly-polarizing plate by another embodiment of this invention. It is a schematic sectional drawing of the circularly-polarizing plate by another embodiment of this invention. It is a principal part disassembled perspective view of the circularly-polarizing plate of FIG. 1A.

  Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.

(Definition of terms and symbols)
The definitions of terms and symbols in this specification are as follows.
(1) Refractive index (nx, ny, nz)
“Nx” is the refractive index in the direction in which the in-plane refractive index is maximum (ie, the slow axis direction), and “ny” is the direction orthogonal to the slow axis in the plane (ie, the fast axis direction). “Nz” is the refractive index in the thickness direction.
(2) In-plane retardation (Re)
“Re (λ)” is an in-plane retardation measured with light having a wavelength of λ nm at 23 ° C. For example, “Re (550)” is an in-plane retardation measured with light having a wavelength of 550 nm at 23 ° C. Re (λ) is obtained by the formula: Re = (nx−ny) × d, where d (nm) is the thickness of the layer (film).
(3) Thickness direction retardation (Rth)
“Rth (λ)” is a retardation in the thickness direction measured with light having a wavelength of λ nm at 23 ° C. For example, “Rth (550)” is a retardation in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C. Rth (λ) is determined by the formula: Rth = (nx−nz) × d, where d (nm) is the thickness of the layer (film).
(4) Nz coefficient The Nz coefficient is obtained by Nz = Rth / Re.

A. Circularly polarizing plate A-1. Overall Configuration of Circular Polarizing Plate The circular polarizing plate of the present invention is used in an organic EL display device. The circularly polarizing plate of the present invention includes a polarizer, a first retardation layer functioning as a λ / 2 plate, a second retardation layer functioning as a λ / 4 plate, and a refractive index of nz> nx ≧ ny. A third retardation layer having an ellipsoid. Hereinafter, the whole structure of a circularly-polarizing plate is demonstrated concretely, Then, each layer and optical film which comprise a circularly-polarizing plate are demonstrated in detail.

  FIG. 1A is a schematic cross-sectional view of a circularly polarizing plate according to one embodiment of the present invention. The circularly polarizing plate 100 of this embodiment includes a polarizer 10, a first protective film 21 disposed on one side of the polarizer 10, a second protective film 22 disposed on the other side of the polarizer 10, A first retardation layer 30, a third retardation layer 50, and a second retardation layer 40 are sequentially arranged on the opposite side of the second protective film 22 from the polarizer 10. That is, the circularly polarizing plate 100 includes the polarizer 10, the first retardation layer 30, the third retardation layer 50, and the second retardation layer 40 in this order. As described above, the first retardation layer 30 functions as a λ / 2 plate, the second retardation layer 40 functions as a λ / 4 plate, and the third retardation layer 50 satisfies nz> nx ≧ ny. It has a refractive index ellipsoid.

  FIG. 1B is a schematic cross-sectional view of a circularly polarizing plate according to another embodiment of the present invention. The circularly polarizing plate 101 of this embodiment further includes a fourth retardation layer 60 having a refractive index ellipsoid of nz> nx ≧ ny. In the present embodiment, the fourth retardation layer 60 is disposed between the second protective film 22 and the first retardation layer 30. That is, the circularly polarizing plate 101 includes the polarizer 10, the fourth retardation layer 60, the first retardation layer 30, the third retardation layer 50, and the second retardation layer 40 in this order. FIG. 1C is a schematic cross-sectional view of a circularly polarizing plate according to still another embodiment of the present invention. In the circularly polarizing plate 102 of the present embodiment, the fourth retardation layer 60 is disposed outside the second retardation layer 40. That is, the circularly polarizing plate 102 includes the polarizer 10, the first retardation layer 30, the third retardation layer 50, the second retardation layer 40, and the fourth retardation layer 60 in this order.

  FIG. 1D is a schematic cross-sectional view of a circularly polarizing plate according to still another embodiment of the present invention. In the circularly polarizing plate 103 of the present embodiment, the first retardation layer 30 and the second retardation layer 40 are adjacent to each other. That is, the circularly polarizing plate 103 includes the polarizer 10, the third retardation layer 50, the first retardation layer 30, the second retardation layer 40, and the fourth retardation layer 60 in this order.

  In any of the above embodiments, the retardation layer adjacent to the second protective film 22 may function as a protective film for the polarizer. Therefore, the second protective film 22 may be omitted depending on the purpose or the like. The third retardation layer 50 and the fourth retardation layer 60 may be the same, and at least one of the constituent material, the thickness, the in-plane retardation, the thickness direction retardation, and the like may be different. .

  The above-described embodiments may be appropriately combined, and techniques well known in the industry may be combined with the above-described embodiments. For example, the fourth retardation layer may be omitted in the embodiment of FIG. 1D, and in the embodiments of FIGS. 1A to 1D, a retardation layer having any appropriate optical characteristic may be arbitrarily selected depending on the purpose. It may be further provided at any position.

In the present invention, the angle formed by the absorption axis A of the polarizer 10 and the slow axis B of the first retardation layer 30 is α (°), and the slow axis B of the first retardation layer 30 and the second retardation axis 30 are the second. When the angle formed by the slow axis C of the retardation layer 40 is β (°), the angles α and β satisfy the following formula (1a) or (1b):
α + 35 ° <β <α + 55 ° (0 ° ≦ α ≦ 90 °) (1a)
α-35 ° <β <α-55 ° (90 ° <α <180 °) (1b).
In the formula (1a), the relationship between the angle α and the angle β is preferably α + 38 ° <β <α + 52 °, more preferably α + 40 ° <β <α + 50 °, and further preferably α + 42 ° <β <α + 48. °, particularly preferably α + 44 ° <β <α + 46 °. In the formula (1b), the relationship between the angle α and the angle β is preferably α−38 ° <β <α−52 °, more preferably α−40 ° <β <α−50 °, Α-42 ° <β <α-48 ° is preferable, and α-44 ° <β <α-46 ° is particularly preferable. FIG. 2 shows the relationship between the angle α and the angle β in the equation (1a). FIG. 2 is an exploded perspective view of the main part of the circularly polarizing plate of FIG. 1A, and the protective films 21 and 22 and the third retardation layer 50 are omitted. The relationship between the angle α and the angle β is the same in the embodiments other than FIG. 1A. When the angles α and β satisfy the expression (1a) or (1b), the first retardation layer (λ / 2 plate) and the second retardation layer (λ / 4 plate) are ideal. A characteristic close to the reverse wavelength dispersion characteristic can be obtained. More specifically, by optimizing the relationship between the angle α and the angle β according to the value of the angle α, the polarization state can be converted in an almost ideal state for each wavelength of RGB. it can. As a result, very excellent antireflection characteristics can be realized.

In one embodiment, the angle α satisfies the following formula (2):
5 ° ≦ α ≦ 85 ° or 95 ° ≦ α ≦ 175 ° (2).
The angle α is preferably 25 ° ≦ α ≦ 65 ° or 115 ° ≦ α ≦ 155 °, more preferably 35 ° ≦ α ≦ 55 ° or 125 ° ≦ α ≦ 145 °, and even more preferably 40 ° ≦ α ≦ 50 ° or 130 ° ≦ α ≦ 140 °. When the angle α satisfies the expression (2), the first retardation layer and the second retardation layer can be made of materials having the same wavelength dispersion characteristics (for example, the same resin). As a result, the retardation value of each retardation layer can be easily controlled, and finally a circularly polarizing plate having a very excellent reflection hue in both the front direction and the oblique direction can be obtained. When the first retardation layer and the second retardation layer are made of materials having different wavelength dispersion characteristics, the angle α can be set to any appropriate value.

A-2. Polarizer Any appropriate polarizer may be adopted as the polarizer 10. Specific examples include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films, and dichroic substances such as iodine and dichroic dyes. Examples thereof include polyene-based oriented films such as those subjected to the dyeing treatment and stretching treatment according to the above, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Preferably, a polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching is used because of excellent optical properties.

  The dyeing with iodine is performed, for example, by immersing a polyvinyl alcohol film in an iodine aqueous solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after the dyeing treatment or may be performed while dyeing. Moreover, you may dye | stain after extending | stretching. If necessary, the polyvinyl alcohol film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment and the like. For example, by immersing a polyvinyl alcohol film in water and washing it before dyeing, not only can the surface of the polyvinyl alcohol film be cleaned and anti-blocking agents can be washed, but the polyvinyl alcohol film can be swollen and dyed. Unevenness can be prevented.

  The thickness of the polarizer is typically about 1 μm to 80 μm.

A-3. First Retardation Layer The first retardation layer 30 can function as a λ / 2 plate as described above. With the first retardation layer functioning as a λ / 2 plate, the wavelength dispersion characteristics of the second retardation layer 40 functioning as a λ / 4 plate (particularly, the wavelength range where the phase difference deviates from λ / 4). The phase difference can be adjusted appropriately. The in-plane retardation Re (550) of such a first retardation layer is 220 nm to 320 nm, preferably 240 nm to 300 nm, and more preferably 250 nm to 280 nm. The first retardation layer 30 typically has a refractive index ellipsoid of nx> ny = nz or nx>ny> nz. The Nz coefficient of the first retardation layer is, for example, 0.9 to 1.3.

  The thickness of the first retardation layer can be set so as to function most appropriately as a λ / 2 plate. In other words, the thickness can be set so as to obtain a desired in-plane retardation. Specifically, the thickness is preferably 1 μm to 80 μm, more preferably 10 μm to 60 μm, and most preferably 30 μm to 50 μm.

The first retardation layer preferably has an absolute value of the photoelastic coefficient of 2 × 10 ⁻¹¹ m ² / N or less, more preferably 2.0 × 10 ⁻¹³ m ² / N to 1.5 × 10 ^−11. m ² / N, more preferably from ^{1.0 × 10 -12 m 2 /N~1.2×10 -11} m 2 / N resin. When the absolute value of the photoelastic coefficient is in such a range, a phase difference change is unlikely to occur when a shrinkage stress is generated during heating. Therefore, by forming the first retardation layer using a resin having such an absolute value of the photoelastic coefficient, thermal unevenness of the obtained organic EL display device can be well prevented.

  The first retardation layer may exhibit a reverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, and has a positive chromatic dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light. It may also be possible to show a flat chromatic dispersion characteristic in which the phase difference value hardly changes depending on the wavelength of the measurement light. It is preferable to exhibit a flat wavelength dispersion characteristic. An axial angle between a λ / 2 plate (first retardation layer) and a λ / 4 plate (second retardation layer) having flat wavelength dispersion characteristics satisfying the above formula (1a) or (1b). It is possible to obtain a characteristic close to an ideal inverse wavelength dispersion characteristic, and as a result, it is possible to realize a very excellent antireflection characteristic. Further, it is possible to realize a very excellent oblique reflection color by a synergistic effect with a third retardation layer (and a fourth retardation layer as necessary) described later. The Re (450) / Re (550) of the first retardation layer is preferably from 0.99 to 1.03, and Re (650) / Re (550) is preferably from 0.98 to 1.02. .

  The first retardation layer may be composed of any appropriate resin film that can satisfy the optical characteristics and mechanical characteristics as described above. Typical examples of such a resin include a cyclic olefin resin or a cellulose resin. Cyclic olefin resins are preferred. This is because more desired wavelength dispersion characteristics are exhibited. The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers). And graft modified products in which these are modified with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

  Examples of the norbornene-based monomer include norbornene and alkyl and / or alkylidene substituted products thereof such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, and 5-butyl. 2-Norbornene, 5-ethylidene-2-norbornene, and the like, polar substituents such as halogens thereof; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or alkylidene Substituents and polar group substituents such as halogen such as 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6- Ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-oct Hydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a -Octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5 8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene and the like; 3-pentamer of cyclopentadiene, for example, 4,9: 5,8-dimethano-3a, 4 4a, 5,8,8a, 9,9a-octahydro-1H-benzoin 4,11: 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentanthracene and the like. It is done.

  In the present invention, other cycloolefins capable of ring-opening polymerization can be used in combination as long as the object of the present invention is not impaired. Specific examples of such cycloolefins include compounds having one reactive double bond such as cyclopentene, cyclooctene, and 5,6-dihydrodicyclopentadiene.

  The cyclic olefin-based resin preferably has a number average molecular weight (Mn) measured by a gel permeation chromatograph (GPC) method using a toluene solvent, preferably 25,000 to 200,000, more preferably 30,000 to 100,000. 000, most preferably 40,000-80,000. When the number average molecular weight is in the above range, a material having excellent mechanical strength, good solubility, moldability, and casting operability can be obtained.

  When the cyclic olefin-based resin is obtained by hydrogenating a ring-opening polymer of a norbornene monomer, the hydrogenation rate is preferably 90% or more, more preferably 95% or more, Most preferably, it is 99% or more. Within such a range, the heat deterioration resistance and light deterioration resistance are excellent.

  As the cyclic olefin resin, various products are commercially available. Specific examples include trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, “Arton” manufactured by JSR, “TOPAS” trade name manufactured by TICONA, and trade names manufactured by Mitsui Chemicals, Inc. “APEL” may be mentioned.

  Any appropriate cellulose resin (typically, an ester of cellulose and an acid) can be adopted as the cellulose resin. Preferred is an ester of cellulose and a fatty acid. Specific examples of such a cellulose resin include cellulose triacetate (triacetyl cellulose: TAC), cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Cellulose triacetate (triacetyl cellulose: TAC) is particularly preferred. This is because it has low birefringence and high transmittance. Many products are commercially available, and TAC is advantageous in terms of availability and cost.

  Specific examples of TAC commercial products are trade names “UV-50”, “UV-80”, “SH-50”, “SH-80”, “TD-80U”, “TD” manufactured by Fuji Photo Film Co., Ltd. -TAC "," UZ-TAC ", trade name" KC series "manufactured by Konica, and trade name" cellulose triacetate 80 [mu] m series "manufactured by Lonza Japan.

  The first retardation layer 30 is obtained, for example, by stretching a film formed from the cyclic olefin resin or the cellulose resin. As a method for forming a film from a cyclic olefin-based resin or a cellulose-based resin, any appropriate forming method can be adopted. Specific examples include compression molding methods, transfer molding methods, injection molding methods, extrusion molding methods, blow molding methods, powder molding methods, FRP molding methods, cast coating methods (for example, casting methods), calendar molding methods, and hot presses. Law. Extrusion molding or cast coating is preferred. This is because the smoothness of the resulting film can be improved and good optical uniformity can be obtained. The molding conditions can be appropriately set according to the composition and type of the resin used, the properties desired for the first retardation layer, and the like. In addition, since many film products are marketed, the said cyclic olefin resin and the said cellulose resin may use the said commercial film as it is for a extending | stretching process.

  The stretching ratio of the film can vary depending on the in-plane retardation value and thickness desired for the first retardation layer, the type of resin used, the thickness of the film used, the stretching temperature, and the like. Specifically, the draw ratio is preferably 1.75 times to 3.00 times, more preferably 1.80 times to 2.80 times, and most preferably 1.85 times to 2.60 times. By stretching at such a magnification, a first retardation layer having an in-plane retardation capable of appropriately exhibiting the effects of the present invention can be obtained.

  The stretching temperature of the film can vary depending on the in-plane retardation value and thickness desired for the first retardation layer, the type of resin used, the thickness of the film used, the stretching ratio, and the like. Specifically, the stretching temperature is preferably 125 ° C to 150 ° C, more preferably 130 ° C to 140 ° C, and most preferably 130 ° C to 135 ° C. By extending | stretching at such temperature, the 1st phase difference layer which has an in-plane phase difference which can exhibit the effect of this invention appropriately can be obtained.

  Any appropriate stretching method can be adopted as the stretching method of the film. Specifically, various stretching methods such as free end stretching, fixed end stretching, free end contraction, and fixed end contraction can be used singly or simultaneously or sequentially. The stretching direction can also be performed in various directions and dimensions such as a horizontal direction, a vertical direction, a thickness direction, and a diagonal direction.

  In one embodiment, the 1st phase contrast layer is formed by carrying out free end uniaxial extension or fixed end uniaxial extension of a resin film. As a specific example of the free end uniaxial stretching, there is a method of stretching between rolls having different peripheral speeds while running the resin film in the longitudinal direction. As a specific example of the fixed end uniaxial stretching, there is a method of stretching in the width direction (lateral direction) while running the resin film in the longitudinal direction.

  In another embodiment, the first retardation layer is produced by continuously and obliquely stretching a long resin film in the direction of an angle α with respect to the longitudinal direction. By adopting oblique stretching, a long stretched film having an orientation angle of α relative to the longitudinal direction of the film (slow axis in the direction of angle α) can be obtained. For example, when laminated with a polarizer Roll-to-roll is possible, and the manufacturing process can be simplified.

  Examples of the stretching machine used for the oblique stretching include a tenter-type stretching machine that can apply a feeding force, a pulling force, or a pulling force at different speeds in the lateral and / or longitudinal direction. The tenter type stretching machine includes a horizontal uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but any suitable stretching machine can be used as long as a long resin film can be continuously stretched obliquely.

A-4. Second Retardation Layer As described above, the second retardation layer 40 can function as a λ / 4 plate. According to the present invention, the wavelength dispersion characteristic of the second retardation layer functioning as a λ / 4 plate is corrected by the optical characteristics of the first retardation layer functioning as the λ / 2 plate, thereby obtaining a wide wavelength range. The circular polarization function in a range can be exhibited. The in-plane retardation Re (550) of the second retardation layer is 100 nm to 180 nm, preferably 110 nm to 170 nm, and more preferably 120 nm to 160 nm. The second retardation layer 40 typically has a refractive index ellipsoid of nx> ny = nz or nx>ny> nz. The Nz coefficient of the second retardation layer is, for example, 0.9 to 1.3.

  The thickness of the second retardation layer can be set so as to function most appropriately as a λ / 4 plate. In other words, the thickness can be set so as to obtain a desired in-plane retardation. Specifically, the thickness is preferably 1 μm to 80 μm, more preferably 10 μm to 60 μm, and most preferably 30 μm to 50 μm.

The absolute value of the photoelastic coefficient of the second retardation layer 40 is preferably 2 × 10 ⁻¹¹ m ² / N or less, more preferably 2.0 × 10 ⁻¹³ m ² / N to 1.5 × 10 ^{−. 11} m ² / N, more preferably includes a resin of ^{1.0 × 10 -12 m 2 /N~1.2×10 -11} m 2 / N. When the absolute value of the photoelastic coefficient is in such a range, a phase difference change is unlikely to occur when a shrinkage stress is generated during heating. Therefore, by forming the second retardation layer using a resin having such an absolute value of the photoelastic coefficient, in combination with the effect of the first retardation layer, an organic EL display device can be obtained. Thermal unevenness can be prevented well.

  The second retardation layer may exhibit a reverse dispersion wavelength characteristic in which the retardation value increases according to the wavelength of the measurement light, and has a positive chromatic dispersion characteristic in which the retardation value decreases according to the wavelength of the measurement light. It may also be possible to show a flat chromatic dispersion characteristic in which the phase difference value hardly changes depending on the wavelength of the measurement light. It is preferable to exhibit a flat wavelength dispersion characteristic. An axial angle between a λ / 2 plate (first retardation layer) and a λ / 4 plate (second retardation layer) having flat wavelength dispersion characteristics satisfying the above formula (1a) or (1b). It is possible to obtain a characteristic close to an ideal inverse wavelength dispersion characteristic, and as a result, it is possible to realize a very excellent antireflection characteristic. Further, it is possible to realize a very excellent oblique reflection color by a synergistic effect with a third retardation layer (and a fourth retardation layer as necessary) described later. The Re (450) / Re (550) of the second retardation layer is preferably from 0.99 to 1.03, and Re (650) / Re (550) is preferably from 0.98 to 1.02. .

  The second retardation layer can be composed of any appropriate resin film that can satisfy the optical characteristics and mechanical characteristics as described above. Typical examples of such a resin include a cyclic olefin resin or a cellulose resin. The details of the cyclic olefin-based resin and the cellulose-based resin are as described in the above section A-3.

  The in-plane retardation Re of the second retardation layer can be controlled by changing the stretching ratio and the stretching temperature of the cyclic olefin resin film and the cellulose resin film described in the section A-3. The draw ratio may vary depending on the in-plane retardation value and thickness desired for the second retardation layer, the type of resin used, the thickness of the film used, the stretching temperature, and the like. Specifically, the draw ratio is preferably 1.15 times to 1.80 times, more preferably 1.25 times to 1.70 times, and most preferably 1.40 times to 1.55 times. By stretching at such a magnification, a second retardation layer having an in-plane retardation capable of appropriately exhibiting the effects of the present invention can be obtained.

  The stretching temperature can vary depending on the in-plane retardation value and thickness desired for the second retardation layer, the type of resin used, the thickness of the film used, the stretching ratio, and the like. Specifically, the stretching temperature is preferably 120 ° C to 150 ° C, more preferably 125 ° C to 140 ° C, and most preferably 125 ° C to 135 ° C. By extending | stretching at such temperature, the 2nd phase difference layer which has the in-plane phase difference which can exhibit the effect of this invention appropriately can be obtained.

  The second retardation layer 40 may be formed of the same material as the first retardation layer 30 or may be formed of a different material. Further, the second retardation layer 40 may be the same as or different from the first retardation layer 30 in terms of refractive index ellipsoid, Nz coefficient, and the like.

A-5. Third Retardation Layer As described above, the third retardation layer 50 has a relationship in which the refractive index characteristic is nz> nx ≧ ny. By providing such a third retardation layer, the function of the λ / 4 plate (second retardation layer) can be sufficiently maintained for light incident from an oblique direction. An excellent oblique reflection color can be realized. The thickness direction retardation Rth (550) of the third retardation layer is preferably −260 nm to −10 nm, more preferably −200 nm to −20 nm, still more preferably −180 nm to −30 nm, and particularly preferably −180 nm to -90 nm.

  In one embodiment, the third retardation layer has a relationship in which the refractive index is nx = ny. Here, “nx = ny” includes not only the case where nx and ny are exactly equal, but also the case where nx and ny are substantially equal. Specifically, Re (550) is less than 10 nm. In another embodiment, the third retardation layer has a refractive index relationship of nx> ny. In this case, the in-plane retardation Re (550) of the third retardation layer is preferably 10 nm to 150 nm, more preferably 10 nm to 80 nm. Preferably, the third retardation layer has a refractive index of nx> ny. By using such a retardation layer, it is possible to preferably compensate for the geometrical axis misalignment between the slow axes of the first retardation layer and the second retardation layer when viewed from the oblique direction, and the oblique direction. This is because the antireflection function can be greatly improved. Note that, as described above, when nx and ny are substantially equal and when nx> ny, a slow axis can appear in the third retardation layer. In this case, when the third retardation layer is disposed between the polarizer and the λ / 2 plate (first retardation layer), its slow axis is relative to the absorption axis of the polarizer. They can be stacked so as to be orthogonal or parallel. When the third retardation layer is disposed between the λ / 2 plate (first retardation layer) and the λ / 4 plate (second retardation layer), the slow axis thereof has an angle 2α. Or it can be laminated so as to be in the direction of 2α + 90 °.

  When the fourth retardation layer is provided as described later, Rth (550) of the third retardation layer and Re (550) when nx> ny are the fourth retardation layer, respectively. Can be shared with Rth (550) and Re (550). For example, in an embodiment in which only the third retardation layer is provided, when Rth (550) of the third retardation layer is −100 nm and Re (550) is 40 nm, a fourth retardation layer is further provided. For example, Rth (550) of the third retardation layer and the fourth retardation layer can be set to −50 nm, and Re (550) can be set to 20 nm. Note that such sharing is not limited to a half-fold as illustrated, and any appropriate ratio can be adopted depending on the purpose or the like. By sharing the phase difference between the third phase difference layer and the fourth phase difference layer, there is an advantage that even a material having a more gentle positive wavelength dispersion characteristic and a lower orientation can be used. Further, in the case where a phase difference layer having a refractive index characteristic of nz> nx> ny is employed as the third phase difference layer and the fourth phase difference layer, an axial arrangement that cancels out the in-plane phase difference from each other; Therefore, the antireflection characteristic in the oblique direction can be improved without affecting the antireflection characteristic in the front direction. As described above, when the refractive index characteristic shows the relationship of nz> nx> ny and in-plane retardation occurs (when the slow axis appears), the third retardation layer and the fourth order When the in-plane phase difference is shared by the phase difference layer, the respective slow axes may be arranged in parallel. When canceling the in-plane retardation with each other, the third retardation layer and the fourth retardation layer may be disposed adjacent to each other, and the respective slow axes may be disposed to be orthogonal to each other.

  The third retardation layer can be formed of any appropriate material. A liquid crystal layer fixed in homeotropic alignment is preferable. The liquid crystal material (liquid crystal compound) that can be homeotropically aligned may be a liquid crystal monomer or a liquid crystal polymer. Specific examples of the liquid crystal compound and the method for forming the liquid crystal layer include the liquid crystal compounds and methods described in JP-A-2002-333642, [0020] to [0042]. In this case, the thickness is preferably 0.1 μm to 5 μm, more preferably 0.2 μm to 3 μm. Since the liquid crystal layer has a very thin thickness and desired optical properties can be obtained, the circularly polarizing plate can be significantly reduced in thickness.

  As another preferred specific example, the third retardation layer may be a retardation film formed of a fumaric acid diester resin described in JP 2012-32784 A. In this case, the thickness is preferably 5 μm to 50 μm, more preferably 10 μm to 35 μm. A retardation film formed of a fumaric acid diester resin has an advantage that a change in hue is small because wavelength dispersion characteristics are close to flat dispersion.

A-6. Fourth Retardation Layer As described above, the fourth retardation layer 60 has a relationship in which the refractive index characteristic is nz> nx ≧ ny. The optical characteristics, constituent materials, and the like of the fourth retardation layer are as described in the above section A-5 in relation to the third retardation layer. As described above, the fourth retardation layer 60 can share the third retardation layer 50 with Rth (550) and Re (550). The fourth retardation layer 60 may be the same as the third retardation layer 50, and at least one of the constituent material, the optical characteristics, and the like may be different from the third retardation layer 50.

A-7. Protective Film The protective films 21 and 22 are formed of any appropriate film that can be used as a protective layer for a polarizer. Specific examples of the material as the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyimide-based, polyethersulfone-based, and polysulfone-based materials. And transparent resins such as polystyrene, polynorbornene, polyolefin, (meth) acryl, and acetate. Further, thermosetting resins such as (meth) acrylic, urethane-based, (meth) acrylurethane-based, epoxy-based, and silicone-based or ultraviolet curable resins are also included. In addition to this, for example, a glassy polymer such as a siloxane polymer is also included. Moreover, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film can be, for example, an extruded product of the resin composition.

  As said (meth) acrylic-type resin, Tg (glass transition temperature) becomes like this. Preferably it is 115 degreeC or more, More preferably, it is 120 degreeC or more, More preferably, it is 125 degreeC or more, Most preferably, it is 130 degreeC or more. It is because it can be excellent in durability. Although the upper limit of Tg of the said (meth) acrylic-type resin is not specifically limited, From viewpoints of a moldability etc., Preferably it is 170 degrees C or less.

As said (meth) acrylic-type resin, arbitrary appropriate (meth) acrylic-type resins can be employ | adopted within the range which does not impair the effect of this invention. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester -(Meth) acrylic acid copolymer, (meth) acrylic acid methyl-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer) And methyl methacrylate- (meth) acrylate norbornyl copolymer). Preferably, poly (meth) acrylic acid C _1-6 alkyl such as poly (meth) acrylate methyl is used. More preferably, a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

  Specific examples of the (meth) acrylic resin include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. Examples of the resin include high Tg (meth) acrylic resins obtained by intramolecular crosslinking or intramolecular cyclization reaction.

  As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure is particularly preferable in that it has high heat resistance, high transparency, and high mechanical strength.

  Examples of the (meth) acrylic resin having the lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. Examples thereof include (meth) acrylic resins having a lactone ring structure described in JP-A-146084.

  The (meth) acrylic resin having the lactone ring structure has a mass average molecular weight (sometimes referred to as a weight average molecular weight) of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, and still more preferably 10,000 to 500,000. Preferably it is 50000-500000.

  The (meth) acrylic resin having a lactone ring structure has a Tg (glass transition temperature) of preferably 115 ° C. or higher, more preferably 125 ° C. or higher, still more preferably 130 ° C. or higher, particularly preferably 135 ° C., most preferably. Is 140 ° C. or higher. It is because it can be excellent in durability. The upper limit of Tg of the (meth) acrylic resin having the lactone ring structure is not particularly limited, but is preferably 170 ° C. or less from the viewpoint of moldability and the like.

  In the present specification, “(meth) acrylic” refers to acrylic and / or methacrylic.

  The first protective film 21 disposed on the opposite side of each retardation layer with respect to the polarizer is subjected to surface treatment such as hard coat treatment, antireflection treatment, antisticking treatment, and antiglare treatment as necessary. May be. The thickness of the first protective film is typically 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and still more preferably 5 μm to 150 μm.

  It is preferable that the 2nd protective film 22 arrange | positioned at the phase difference layer side of a polarizer is optically isotropic. In this specification, “optically isotropic” means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is −10 nm to +10 nm. Say.

  The thickness of the second protective film is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm, and still more preferably 15 μm to 95 μm.

A-8. Others Arbitrary appropriate adhesive layers or adhesive layers are used for lamination | stacking of each layer which comprises the circularly-polarizing plate of this invention. The pressure-sensitive adhesive layer is typically formed of an acrylic pressure-sensitive adhesive. The adhesive layer is typically formed of a polyvinyl alcohol-based adhesive.

  Although not shown, an adhesive layer may be provided on the outermost retardation layer surface of the circularly polarizing plate. By providing the pressure-sensitive adhesive layer in advance, it can be easily bonded to another optical member (for example, an organic EL display device). In addition, it is preferable that the peeling film is bonded together on the surface of this adhesive layer until it uses.

B. Organic EL Display Device The organic EL display device of the present invention includes the circularly polarizing plate described in the above section A on the viewing side. The circularly polarizing plate is laminated so that each retardation layer is on the organic EL panel side (so that the polarizer is on the viewing side).

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In addition, the measuring method of each characteristic is as follows.

(1) Thickness The thickness was measured using a dial gauge (manufactured by PEACOCK, product name “DG-205”, dial gauge stand (product name “pds-2”)).
(2) Retardation A 50 mm × 50 mm sample was cut out from each retardation layer, and measured using a measurement sample and Axoscan manufactured by Axometrics. The measurement wavelength was 550 nm and the measurement temperature was 23 ° C.
Moreover, the average refractive index was measured using an Abbe refractometer manufactured by Atago Co., Ltd., and the refractive indexes nx, ny, and nz were calculated from the obtained retardation values.
(3) Reflectivity With a black screen with the screen of the obtained organic EL panel turned off, the reflectivity in the oblique direction was measured using a viewing angle measurement evaluation apparatus conoscope manufactured by Autronics-MERCHERS. Specifically, the reflectance at an azimuth angle of 0 ° to 360 ° in the polar angle of 60 ° direction was measured every 15 °, and the average was defined as the oblique reflectance. The reflectance in the front direction was measured using a spectrocolorimeter 2600D manufactured by Konica Minolta. For each of the reflectance in the front direction and the oblique direction, evaluation was made with ○ being acceptable for practical use and × for being unacceptable.

[Example 1]
<Preparation of first retardation layer (λ / 2 plate)>
An unstretched film made of a norbornene resin having a photoelastic coefficient of 11 × 10 ⁻¹² m ² / N, Tg of 125 ° C. and a thickness of 70 μm is uniaxially stretched by 2.552 times in an atmosphere of 133 ° C. A film was obtained. The in-plane retardation Re (550) of this retardation film was 270 nm. This retardation film was used as a first retardation layer.

<Preparation of Second Retardation Layer (λ / 4 Plate)>
An unstretched film made of norbornene resin having a photoelastic coefficient of 11 × 10 ⁻¹² m ² / N, Tg of 125 ° C. and a thickness of 50 μm is uniaxially stretched by 1.526 times in an atmosphere of 128 ° C., and the thickness is about 40 μm. A phase difference film was obtained. The in-plane retardation Re (550) of this retardation film was 140 nm. This retardation film was used as a second retardation layer.

<Preparation of third retardation layer>
20 parts by weight of a side chain type liquid crystal polymer represented by the following chemical formula (I) (numbers 65 and 35 in the formula indicate mol% of the monomer units and are represented by block polymer for convenience: weight average molecular weight 5000), Dissolve 80 parts by weight of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF: trade name: Palicolor LC242) and 5 parts by weight of a photopolymerization initiator (trade name: Irgacure 907, manufactured by Ciba Specialty Chemicals) in 200 parts by weight of cyclopentanone. Thus, a liquid crystal coating solution was prepared. And after apply | coating the said coating liquid to a base film (norbornene-type resin film: Nippon Zeon Co., Ltd. make, brand name "ZEONEX") with a bar coater, a liquid crystal is dried by heating at 80 degreeC for 4 minutes. Oriented. The liquid crystal layer was irradiated with ultraviolet rays to cure the liquid crystal layer, thereby forming a liquid crystal solidified layer (thickness: 0.8 μm) serving as a third retardation layer on the substrate. This layer has Re (550) of 0 nm and Rth (550) of −98 nm (nx: 1.5326, ny: 1.5326, nz: 1.6550), and exhibits a refractive index characteristic of nz> nx = ny. It was.

<Production of polarizer>
The polyvinyl alcohol film was dyed in an aqueous solution containing iodine and then uniaxially stretched 6 times between rolls having different speed ratios in an aqueous solution containing boric acid to obtain a polarizer.

<Production of circularly polarizing plate>
A triacetyl cellulose film (thickness 40 μm, manufactured by Konica Minolta, trade name “KC4UYW”) was bonded to one side of the polarizer via a polyvinyl alcohol-based adhesive.
A retardation film (first retardation layer) was bonded to the other side of the polarizer via a polyvinyl alcohol-based adhesive. Next, after the liquid crystal solidified layer is bonded to the retardation film side via an acrylic adhesive, the substrate film is peeled and removed, and the retardation film is further peeled off via an acrylic adhesive. (Second retardation layer) was bonded. Thus, the circularly-polarizing plate which has the structure of protective film / polarizer / first retardation layer / third retardation layer / second retardation layer was obtained. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer is 60 °, and the angle α and the angle β satisfy the following formula (1a):
α + 35 ° <β <α + 55 ° (0 ° ≦ α ≦ 90 °) (1a).

<Production of organic EL display device>
The pressure-sensitive adhesive layer was formed with an acrylic pressure-sensitive adhesive on the second retardation layer side of the obtained circularly polarizing plate, and cut into dimensions of 50 mm × 50 mm.
Take out the organic EL panel from the organic EL display (Samsung, product name “Galaxy S4”), peel off the polarizing film attached to the organic EL panel, and paste the cut circular polarizing plate instead. An organic EL display device was obtained. The obtained organic EL display device was subjected to the evaluation of (3) above. The results are shown in Table 1.

[Example 2]
A third retardation layer was prepared as follows: in a 30 liter autoclave, 18 kg of distilled water containing 0.2 wt% of partially saponified polyvinyl alcohol, 3 kg of diisopropyl fumarate, and dimethyl-2 as a polymerization initiator , 2′-azobisisobutyrate 7 g was charged, and a suspension radical polymerization reaction was carried out under conditions of a polymerization temperature of 50 ° C. and a polymerization time of 24 hours. The obtained particles were filtered, sufficiently washed with methanol, and dried at 80 ° C. to obtain a diisopropyl fumarate homopolymer. The obtained diisopropyl fumarate homopolymer was dissolved in a THF solution to give a 22% solution, and tris (2,4-di-) was used as a hindered phenol antioxidant for 100 parts by weight of the diisopropyl fumarate homopolymer. tert-butylphenyl) phosphite 0.35 parts by weight and pentaerythritol-tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate) 0.15 parts by weight as a phosphorus-based antioxidant, After adding 1 part by weight of 2- (2H-benzotriazol-2-yl) -p-cresol as an ultraviolet absorber, it was cast on a support substrate of a solution casting apparatus by the T-die method, A retardation film (third retardation layer) having a thickness of 20.7 μm and dried for 15 minutes at 120 ° C. was obtained. Re (550) of the obtained retardation film was 0 nm, Rth (550) was −102 nm, and exhibited refractive index characteristics of nz> nx = ny.
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Example 1 except that the third retardation layer obtained above was used. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 60 °, and the angle α and the angle β satisfied the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 3]
A third retardation film for a retardation layer was produced in the same manner as in Example 2. Furthermore, the obtained retardation film was cut into a length of 300 mm and a width of 300 mm, and free end longitudinal stretching was performed at a temperature of 150 ° C. and a magnification of 1.05 times using a lab stretcher KARO IV (manufactured by Bruckner). A phase difference film (third phase difference layer) was obtained. Re (550) of the obtained retardation film was 20 nm, Rth (550) was -119 nm, and showed refractive index characteristics of nz>nx> ny.
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Example 1 except that the third retardation layer obtained above was used. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 60 °, and the angle α and the angle β satisfied the relationship of the above formula (1a). The angle formed by the slow axis of the third retardation layer and the absorption axis of the polarizer was 30 °. Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 4]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Example 2 except that the angle β at the time of laminating the first retardation layer and the second retardation layer was changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 65 °, and the angle α and the angle β satisfied the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 5]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Example 2 except that the angle β at the time of laminating the first retardation layer and the second retardation layer was changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 55 °, and the angle α and the angle β satisfied the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 6]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Example 2 except that the angle α at the time of laminating the first retardation layer and the second retardation layer was changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 75 °, and the slow axis of the first retardation layer and the second retardation layer The angle β formed by the slow axis of the retardation layer was 120 °, and the angle α and the angle β satisfied the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 7]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Example 2 except that the angle α at the time of laminating the first retardation layer and the second retardation layer was changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 105 °, and the slow axis of the first retardation layer and the second retardation layer The angle β formed by the slow axis of the retardation layer was 60 °, and the angle α and the angle β satisfied the relationship of the following formula (1b).
α-35 ° <β <α-55 ° (90 ° <α <180 °) (1b)
Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 8]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Example 2 except that the angle α at the time of laminating the first retardation layer and the second retardation layer was changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 165 °, and the slow axis of the first retardation layer and the second retardation layer The angle β formed by the slow axis of the retardation layer is 120 °, and the angle α and the angle β satisfy the relationship of the above formula (1b). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 9]
A third retardation layer was produced in the same manner as in Example 1 except that the thickness direction retardation Rth (550) was changed to −50 nm. Furthermore, a fourth retardation layer was produced according to the method for producing the third retardation layer. The third retardation layer and the fourth retardation layer exhibited refractive index characteristics of nz> nx = ny, respectively. The Re (550) of the third retardation layer and the fourth retardation layer are each 0 nm, the Rth (550) of the third retardation layer is −50 nm, and the Rth ( 550) was -110 nm. Protective film / polarizer / fourth retardation layer / first in the same manner as in Example 1 except that a fourth retardation layer was further bonded between the polarizer and the first retardation layer. A circularly polarizing plate having a configuration of retardation layer / third retardation layer / second retardation layer was obtained. Further, an organic EL display device was obtained in the same manner as in Example 1. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 60 °, and the angle α and the angle β satisfied the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 10]
A third retardation layer was produced in the same manner as in Example 3. Further, a fourth retardation layer was produced in the same manner as the third retardation layer of Example 2. The third retardation layer and the fourth retardation layer exhibited refractive index characteristics of nz>nx> ny, respectively. The Re (550) of the third retardation layer and the fourth retardation layer are each 20 nm, the Rth (550) of the third retardation layer is −120 nm, and the Rth ( 550) was -100 nm. Protective film / polarizer / fourth retardation layer / first in the same manner as in Example 3 except that a fourth retardation layer was further bonded between the polarizer and the first retardation layer. A circularly polarizing plate having a configuration of retardation layer / third retardation layer / second retardation layer was obtained. Further, an organic EL display device was obtained in the same manner as in Example 1. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 60 °, and the angle α and the angle β satisfied the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 11]
Protective film / polarizer / first retardation layer / in the same manner as in Example 9 except that the bonding position of the fourth retardation layer was changed and bonded to the outside of the second retardation layer. A circularly polarizing plate having a configuration of third retardation layer / second retardation layer / fourth retardation layer was obtained. Further, an organic EL display device was obtained in the same manner as in Example 1. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 60 °, and the angle α and the angle β satisfied the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 12]
Protective film / polarizer / first retardation layer / in the same manner as in Example 10 except that the bonding position of the fourth retardation layer was changed and bonded to the outside of the second retardation layer. A circularly polarizing plate having a configuration of third retardation layer / second retardation layer / fourth retardation layer was obtained. Further, an organic EL display device was obtained in the same manner as in Example 1. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 60 °, and the angle α and the angle β satisfied the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 13]
The protective film / polarizer / third retardation layer / first retardation layer / is the same as in Example 11 except that the arrangement order of the first retardation layer and the third retardation layer was changed. A circularly polarizing plate having a configuration of second retardation layer / fourth retardation layer was obtained. Further, an organic EL display device was obtained in the same manner as in Example 1. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 60 °, and the angle α and the angle β satisfied the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 14]
Implemented except that the arrangement order of the first retardation layer and the third retardation layer was changed, and that the slow axis of the third retardation layer was arranged parallel to the absorption axis of the polarizer. In the same manner as in Example 12, a circularly polarizing plate having a configuration of protective film / polarizer / third retardation layer / first retardation layer / second retardation layer / fourth retardation layer was obtained. . Further, an organic EL display device was obtained in the same manner as in Example 1. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 60 °, and the angle α and the angle β satisfied the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
A circularly polarizing plate having the structure of protective film / polarizer / first retardation layer / second retardation layer was obtained in the same manner as in Example 1 except that the third retardation layer was not provided. . Further, an organic EL display device was obtained in the same manner as in Example 1. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 60 °, and the angle α and the angle β satisfied the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Comparative Example 1 except that the angle β at the time of laminating the first retardation layer and the second retardation layer was changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 75 °, and the angle α and the angle β did not satisfy the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Comparative Example 1 except that the angle α at the time of laminating the first retardation layer and the second retardation layer was changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 0 °, and the slow axis of the first retardation layer and the second retardation layer The angle β formed by the slow axis of the retardation layer was 45 °, and the angle α and the angle β satisfied the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 4]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Comparative Example 1 except that the angles α and β at the time of laminating the first retardation layer and the second retardation layer were changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 90 °, and the slow axis of the first retardation layer and the second retardation layer The angle β formed by the slow axis of the retardation layer was 120 °, and the angle α and the angle β did not satisfy the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 5]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Example 2 except that the angle β at the time of laminating the first retardation layer and the second retardation layer was changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 75 °, and the angle α and the angle β did not satisfy the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 6]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Example 2 except that the angle α at the time of laminating the first retardation layer and the second retardation layer was changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 0 °, and the slow axis of the first retardation layer and the second retardation layer The angle β formed by the slow axis of the retardation layer was 60 °, and the angle α and the angle β did not satisfy the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 7]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Example 2 except that the angles α and β at the time of laminating the first retardation layer and the second retardation layer were changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 90 °, and the slow axis of the first retardation layer and the second retardation layer The angle β formed by the slow axis of the retardation layer was 120 °, and the angle α and the angle β did not satisfy the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 8]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Example 13 except that the angle β at the time of laminating the first retardation layer and the second retardation layer was changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 15 °, and the slow axis of the first retardation layer and the second retardation layer are The angle β formed by the slow axis of the retardation layer was 75 °, and the angle α and the angle β did not satisfy the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 9]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Example 13 except that the angle α at the time of laminating the first retardation layer and the second retardation layer was changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 0 °, and the slow axis of the first retardation layer and the second retardation layer The angle β formed by the slow axis of the retardation layer was 60 °, and the angle α and the angle β did not satisfy the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 10]
A circularly polarizing plate and an organic EL display device were obtained in the same manner as in Example 13 except that the angles α and β at the time of laminating the first retardation layer and the second retardation layer were changed. In the obtained circularly polarizing plate, the angle α formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is 90 °, and the slow axis of the first retardation layer and the second retardation layer The angle β formed by the slow axis of the retardation layer was 120 °, and the angle α and the angle β did not satisfy the relationship of the above formula (1a). Furthermore, the obtained organic EL display device was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Evaluation>
As is clear from Table 1, the organic EL display device using the circularly polarizing plate of the example of the present invention had a low reflectance in both the front direction and the oblique direction, and exhibited good antireflection performance. On the other hand, the circularly polarizing plates of Comparative Examples 1 and 3 that satisfy the formula (1) but are not provided with the third retardation layer having a refractive index ellipsoid of nz> nx ≧ ny have antireflection performance in the front direction. Was excellent, but the antireflection performance in the oblique direction was insufficient. The anti-reflection performance of the circularly polarizing plate of each comparative example that does not satisfy the formula (1) was insufficient in both the front direction and the oblique direction.

  The circularly polarizing plate of the present invention is suitably used for an organic EL display device.

DESCRIPTION OF SYMBOLS 10 Polarizer 20 Protective film 21 1st protective film 22 2nd protective film 30 1st phase difference layer ((lambda) / 2 board)
40 Second retardation layer (λ / 4 plate)
50 Third retardation layer 60 Fourth retardation layer 100 Circularly polarizing plate 101 Circularly polarizing plate 102 Circularly polarizing plate 103 Circularly polarizing plate

Claims (9)

A third position having a polarizer, a first retardation layer functioning as a λ / 2 plate, a second retardation layer functioning as a λ / 4 plate, and a refractive index ellipsoid of nz> nx ≧ ny. A phase difference layer,
The angle formed by the absorption axis of the polarizer and the slow axis of the first retardation layer is α (°), and the slow axis of the first retardation layer and the slow phase of the second retardation layer A circularly polarizing plate for an organic EL display device in which the angles α and β satisfy the following formula (1a) or (1b) when the angle formed by the axis is β (°):
α + 35 ° <β <α + 55 ° (0 ° ≦ α ≦ 90 °) (1a)
α-35 ° <β <α-55 ° (90 ° <α <180 °) (1b).   The circularly polarizing plate for an organic EL display device according to claim 1, comprising the polarizer, the first retardation layer, the third retardation layer, and the second retardation layer in this order.   The circularly polarizing plate for an organic EL display device according to claim 1, further comprising a fourth retardation layer having a refractive index ellipsoid of nz> nx ≧ ny.   The organic EL display according to claim 3, comprising the polarizer, the fourth retardation layer, the first retardation layer, the third retardation layer, and the second retardation layer in this order. Circular polarizing plate for equipment.   The organic EL display according to claim 3, comprising the polarizer, the first retardation layer, the third retardation layer, the second retardation layer, and the fourth retardation layer in this order. Circular polarizing plate for equipment.   The organic EL display according to claim 3, comprising the polarizer, the third retardation layer, the first retardation layer, the second retardation layer, and the fourth retardation layer in this order. Circular polarizing plate for equipment.   The circle for organic EL display devices according to claim 1, wherein at least one of the third retardation layer and the fourth retardation layer has a refractive index ellipsoid of nz> nx> ny. Polarizer. The circular polarizing plate for an organic EL display device according to claim 1, wherein the angle α satisfies the following formula (2):
5 ° ≦ α ≦ 85 ° or 95 ° ≦ α ≦ 175 ° (2). An organic EL display device comprising the circularly polarizing plate according to claim 1.

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