Polarizing plate and optical display device including the same

Abstract

The present invention relates to a polarizing plate and an optical display device including the polarizing plate. The polarizing plate includes a polarizer; and a first phase difference layer and a second phase difference layer sequentially stacked on the lower surface of the polarizer, wherein the first phase difference layer has an in-plane phase difference of about 180 nm to about 220 nm at a wavelength of about 550 nm; and the second phase difference layer has an in-plane phase difference of about 80 nm to about 100 nm at a wavelength of about 550 nm.

Description

[0001] Citations of Related Applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2020-0091948 filed on Jul. 23, 2020, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0003] The present invention relates to a polarizing plate and an optical display device including the polarizing plate. More specifically, the present invention relates to a polarizing plate having low reflectivity on both the front and side surfaces of a screen and having an ellipticity of about 65% or more at an incident angle of about 60° and allowing its thickness to be reduced, and an optical display device including the polarizing plate. Background Art

[0004] Due to the reflection of external light, the visibility and contrast of the organic light emitting diode display may be damaged. In order to solve this problem, a polarizing plate including a polarizer and a phase difference film is used to achieve an anti-reflection function by preventing the reflected external light from leaking out.

[0005] The phase difference film may include a single 1 / 4 phase difference layer or may be a laminate of a 1 / 2 phase difference layer and a 1 / 4 phase difference layer. However, a polarizing plate including a single 1 / 4 phase difference layer or a laminate of a 1 / 2 phase difference layer and a 1 / 4 phase difference layer has a limitation in achieving an ellipticity of about 65% or more at an incident angle of about 60°. In addition, with the recent trend of reducing the thickness of the polarizing plate, it is necessary to reduce not only the thickness of the polarizer but also the thickness of the phase difference layer.

[0006] The background art of the present invention is disclosed in KR Patent Publication No. 10-2013-0103595 and the like. Summary of the invention

[0007] Aspects of the present invention provide a polarizing plate having low reflectivity on both the front and side surfaces of a screen.

[0008] Another aspect of the present invention provides a polarizing plate having an ellipticity of about 65% or more at an incident angle of about 60°.

[0009] Another aspect of the present invention provides a polarizing plate in which the thickness of a phase difference layer is effectively reduced.

[0010] One aspect of the present invention relates to a polarizing plate.

[0011] 1. The polarizing plate comprises a polarizer; and a first phase difference layer and a second phase difference layer sequentially stacked on a lower surface of the polarizer, wherein the first phase difference layer has an in-plane phase difference of about 180 nm to about 220 nm at a wavelength of about 550 nm; and the second phase difference layer has an in-plane phase difference of about 80 nm to about 100 nm at a wavelength of about 550 nm.

[0012] 2. In 1, the first phase difference layer may be a 1 / 3 phase difference layer at a wavelength of about 550 nm, and the second phase difference layer may be a 1 / 6 phase difference layer at a wavelength of about 550 nm.

[0013] 3. In 1 and 2, the first phase difference layer may have a slow axis tilted at an angle of about +55° to about +80° or at an angle of about -80° to about -55° with respect to a transmission axis of a polarizer.

[0014] 4. In 1 to 3, the second phase difference layer may have a slow axis tilted at an angle of about 0° to about +10° or at an angle of about -10° to about 0° with respect to a transmission axis of a polarizer.

[0015] 5. In 1 to 4, the first phase difference layer and the second phase difference layer may satisfy at least one of the following relationships ① to ⑧:

[0016] ① When 0°<θ[fast axis-absorption axis of the first phase difference layer]<90°,

[0017] θ[fast axis-absorption axis of the second phase difference layer]=θ[fast axis-absorption axis of the first phase difference layer]×2+45+α, 4°≤α≤6°;

[0018] ②-90°<θ[slow axis-absorption axis of the first phase difference layer]<0°,

[0019] θ[slow axis - absorption axis of the second phase difference layer] = θ[slow axis - absorption axis of the first phase difference layer] × 2-45 + α, 4°≤α≤6°;

[0020] ③When -90°<θ[fast axis-absorption axis of the first phase difference layer]<0°,

[0021] θ[fast axis-absorption axis of the second phase difference layer]=θ[fast axis-absorption axis of the first phase difference layer]×2-45-α, 4°≤α≤6°;

[0022] ④ When 0°<θ[slow axis-absorption axis of the first phase difference layer]<90°,

[0023] θ[slow axis - absorption axis of the second phase difference layer] = θ[slow axis - absorption axis of the first phase difference layer] × 2-45-α, 4°≤α≤6°,

[0024] (In ①, ②, ③ and ④,

[0025] θ[fast axis - absorption axis of the first retardation layer] is the angle of the fast axis of the first retardation layer relative to the absorption axis of the polarizer (unit: °),

[0026] θ[slow axis of the first retardation layer - absorption axis] is the angle of the slow axis of the first retardation layer relative to the absorption axis of the polarizer (unit: °),

[0027] θ[fast axis - absorption axis of the second retardation layer] is the angle of the fast axis of the second retardation layer relative to the absorption axis of the polarizer (unit: °), and

[0028] θ[slow axis of the second retardation layer - absorption axis] is the angle of the slow axis of the second retardation layer relative to the absorption axis of the polarizer (unit: °);

[0029] ⑤When 0°<θ[slow axis-transmission axis of the first phase difference layer]<90°,

[0030] θ[slow axis - transmission axis of the second phase difference layer] = θ[slow axis - transmission axis of the first phase difference layer] × 2 + 45 + α, 4° ≤ α ≤ 6°;

[0031] ⑥ When -90°<θ[fast axis-transmission axis of the first phase difference layer]<0°,

[0032] θ[fast axis - transmission axis of the second phase difference layer] = θ[fast axis - transmission axis of the first phase difference layer] × 2-45 + α, 4°≤α≤6°;

[0033] ⑦ When -90°<θ[slow axis-transmission axis of the first phase difference layer]<0°,

[0034] θ[slow axis - transmission axis of the second phase difference layer] = θ[slow axis - transmission axis of the first phase difference layer] × 2-45-α, 4°≤α≤6°; and

[0035] ⑧When 0°<θ[fast axis-transmission axis of the first phase difference layer]<90°,

[0036] θ[fast axis - transmission axis of the second phase difference layer] = θ[fast axis - transmission axis of the first phase difference layer] × 2-45-α, 4°≤α≤6°,

[0037] (In ⑤, ⑥, ⑦ and ⑧,

[0038] θ[fast axis of the first retardation layer - transmission axis] is the angle of the fast axis of the first retardation layer relative to the transmission axis of the polarizer (unit: °),

[0039] θ[slow axis of the first retardation layer - transmission axis] is the angle of the slow axis of the first retardation layer relative to the transmission axis of the polarizer (unit: °),

[0040] θ[fast axis of the second retardation layer - transmission axis] is the angle of the fast axis of the second retardation layer relative to the transmission axis of the polarizer (unit: °), and

[0041] θ[slow axis of the second retardation layer - transmission axis] is the angle (unit: °) of the slow axis of the second retardation layer relative to the transmission axis of the polarizer.

[0042] 6. In 1 to 5, an angle defined between a slow axis of the first phase difference layer and a slow axis of the second phase difference layer may be in a range of about 55° to about 80°.

[0043] 7. In 1 to 6, the first phase difference layer may exhibit positive dispersion or flat dispersion, and the second phase difference layer may exhibit positive dispersion.

[0044] 8. In 1 to 7, the laminate of the first phase difference layer and the second phase difference layer may have an in-plane phase difference of about 140 nm to about 190 nm at a wavelength of about 550 nm.

[0045] 9. In 1 to 8, the first phase difference layer may have an out-of-plane phase difference (Rth) of about 100 nm to about 150 nm at a wavelength of about 550 nm.

[0046] 10. In 1 to 9, the first phase difference layer may have a biaxiality (NZ) of about 1.1 to about 1.2 at a wavelength of about 550 nm.

[0047] 11. In 1 to 10, the second phase difference layer may have an out-of-plane phase difference (Rth) of about -100 nm to about -50 nm at a wavelength of about 550 nm.

[0048] 12. In 1 to 11, the second phase difference layer may have a biaxiality (NZ) of about -0.5 to about -0.2 at a wavelength of about 550 nm.

[0049] 13. In 1 to 12, the first phase difference layer may include a film formed of a resin having positive (+) birefringence.

[0050] 14. In 1 to 13, the second phase difference layer may include a coating layer formed by stretching a film formed of at least one selected from cellulose ester resin and aromatic resin.

[0051] 15. In 1 to 14, the polarizing plate may further include a third phase difference layer including a positive C plate having an out-of-plane phase difference (Rth) of about -300 nm to about 0 nm at a wavelength of about 550 nm.

[0052] 16. In 15, the third phase difference layer may have an out-of-plane phase difference (Rth) of about -80 nm to about -20 nm at a wavelength of about 550 nm.

[0053] 17. In 15, the third phase difference layer may be inserted between the polarizer and the first phase difference layer.

[0054] 18. In 1 to 16, the polarizing plate may further include a protective layer formed on an upper surface of the polarizer.

[0055] Another aspect of the invention relates to an optical display device.

[0056] The optical display device includes the polarizing plate according to the present invention.

[0057] The present invention provides a polarizing plate having low reflectivity on both the front and side surfaces.

[0058] The present invention provides a polarizing plate having an ellipticity of about 65% or more at an incident angle of about 60°.

[0059] The present invention provides a polarizing plate in which the thickness of a phase difference layer can be effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 is a cross-sectional view of a polarizing plate according to one embodiment of the present invention.

[0061] Figure 2 is a view showing an arrangement relationship among a transmission axis of a polarizer, a slow axis of a first phase difference layer, and a slow axis of a second phase difference layer in a polarizing plate according to an embodiment of the present invention. DETAILED DESCRIPTION

[0062] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings to provide a full understanding of the present invention to those skilled in the art. It should be understood that the present invention can be embodied in different ways and is not limited to the following embodiments.

[0063] In the drawings, components irrelevant to the description are omitted in order to clearly describe the present invention, and similar components are represented by similar figure numbers throughout the specification. Although the length, thickness or width of multiple components may be exaggerated in the drawings for understanding, the present invention is not limited thereto.

[0064] In this document, spatially relative terms such as "upper" and "lower" are defined according to the accompanying drawings. Therefore, it will be understood that the term "upper surface" and the term "lower surface" can be used interchangeably.

[0065] In this article, "in-plane retardation (Re)", "out-of-plane retardation (Rth)" and "biaxiality (NZ)" are represented by equations A, B and C, respectively:

[0066] [Equation A]

[0067] Re=(nx-ny)×d

[0068] [Equation B]

[0069] Rth=((nx+ny) / 2-nz)×d

[0070] [Equation C]

[0071] NZ=(nx-nz) / (nx-ny)

[0072] Wherein nx, ny and nz are the refractive indices in the slow axis direction, the fast axis direction and the thickness direction of the optical device at the measurement wavelength, respectively, and d is the thickness of the optical device (unit: nm). In equations A to C, the measurement wavelength can be about 450 nm, about 550 nm or about 650 nm.

[0073] Herein, “short wavelength dispersion” refers to Re(450) / Re(550) and “long wavelength dispersion” refers to Re(650) / Re(550), where Re(450), Re(550) and Re(650) represent the in-plane phase difference (Re) of a single phase difference layer or a laminate of phase difference layers at wavelengths of about 450 nm, about 550 nm and about 650 nm, respectively.

[0074] As used herein to express angles, "+" indicates counterclockwise relative to a reference, while "-" indicates clockwise relative to a reference, assuming that the reference (eg, the transmission axis of a polarizer) is 0°.

[0075] As used herein, in order to express a specific numerical range, the expression “X to Y” means “greater than or equal to X and less than or equal to Y (X≤ and ≤Y)”.

[0076] The polarizing plate according to the present invention achieves a reduction in thickness by reducing the total thickness of the first phase difference layer and the second phase difference layer, and achieves low reflectivity on both the front and side surfaces, and achieves an ellipticity of about 65% or more at an incident angle of about 60°, thereby enabling a significant improvement in screen quality by applying to an optical display device.

[0077] In one embodiment, by being applied to an optical display device, the polarizing plate can have a specular component excluded (SCE) reflectivity of about 1.5% or less, preferably about 0% to about 1.4%, and a SCE reflectivity of about 3% or less, preferably about 0% to about 2.8%, at an incident angle of about 60° on the front side of the screen. Within this range, the polarizing plate can improve the screen quality.

[0078] In one embodiment, by being applied to an optical display device, at an incident angle of about 60°, the polarizing plate may have an ellipticity of about 65% or more, for example, about 65% to about 80% or about 75% to about 80%. Within this range, the polarizing plate may improve screen quality (minimizing color change at an incident angle of about 60° and at an azimuth angle of about 0° to about 360°).

[0079] Then, refer to Figure 1 A polarizing plate according to an embodiment of the present invention is described.

[0080] refer to Figure 1 The polarizing plate includes a polarizer 110, a protective film 140 stacked on the upper surface of the polarizer 110, and a first phase difference layer 120 and a second phase difference layer 130 sequentially stacked in the stated order on the lower surface of the polarizer 110. The protective film 140 is an example of a protective layer including a protective coating or the like.

[0081] In the polarizing plate, the first phase difference layer 120 and the second phase difference layer 130 are sequentially stacked on the lower surface of the polarizer 110. With this structure, the polarizing plate can achieve a reduction in reflectivity and an ellipticity of about 65% or more at the front and at an incident angle of about 60°. The polarizing plate including the second phase difference layer 130 and the first phase difference layer 120 sequentially stacked on the lower surface of the polarizer 110 cannot achieve the effect of the present invention.

[0082] The second phase difference layer 130 may be formed directly on the first phase difference layer 120. In this article, "directly formed" means that no adhesive layer or bonding layer is inserted between the first phase difference layer and the second phase difference layer. In other embodiments, the second phase difference layer may be formed by a transfer film method and stacked on the first phase difference layer by a pressure sensitive adhesive (PSA) or the like.

[0083] In addition, a specific optical layer may be further inserted between the first phase difference layer and the second phase difference layer as long as the other optical layer does not affect the effect achieved by each of the first phase difference layer and the second phase difference layer or the effect achieved by the combination of the first phase difference layer and the second phase difference layer.

[0084] The first phase difference layer

[0085] The first phase difference layer 120 may have an in-plane phase difference of about 180nm to about 220nm (e.g., 180nm, 190nm, 200nm, 210nm, or 220nm) at a wavelength of about 550nm. Therefore, when combined with a second phase difference layer having an in-plane phase difference of about 80nm to about 100nm (e.g., 80nm, 90nm, or 100nm) at a wavelength of about 550nm, the first phase difference layer 120 can achieve a significant reduction in reflectivity on both the front and side of the screen and an ellipticity of about 65% or more at an incident angle of about 60°. Preferably, the first phase difference layer 120 has an in-plane phase difference of about 200nm to 210nm at a wavelength of about 550nm. In one embodiment, the first phase difference layer may be a 1 / 3 phase difference layer at a wavelength of about 550nm.

[0086] In one embodiment, the first phase difference layer 120 may exhibit positive dispersion or flat dispersion (short wavelength dispersion: 1, long wavelength dispersion: 1), specifically a short wavelength dispersion of about 1 to about 1.1 and a long wavelength dispersion of about 0.96 to about 1. Within this range, the polarizing plate can reduce reflectivity on both the front and side surfaces while improving ellipticity. Preferably, the first phase difference layer exhibits a short wavelength dispersion of about 1 to about 1.06 and a long wavelength dispersion of about 0.98 to about 1, about 0.99 to about 1, or about 0.995 to about 1.

[0087] At a wavelength of about 550 nm, the first phase difference layer 120 may have an out-of-plane phase difference (Rth) of about 100 nm to about 150 nm (e.g., 100 nm, 110 nm, 120 nm, 130 nm, 140 nm or 150 nm), preferably about 105 nm to about 140 nm. Within this range, the first phase difference layer may improve lateral reflectivity.

[0088] At a wavelength of about 550 nm, the first phase difference layer 120 may have a biaxiality of about 1.1 to about 1.2 (e.g., 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19 or 1.2), preferably about 1.1 to about 1.15. Within this range, the first phase difference layer can improve lateral reflectivity.

[0089] The first phase difference layer 120 may be a non-liquid crystal layer and may include a film formed of an optically transparent resin. The "non-liquid crystal layer" may refer to a layer that is not formed of at least one selected from a liquid crystal monomer, a liquid crystal oligomer, and a liquid crystal polymer, or a layer formed of a material that is not converted into a liquid crystal monomer, a liquid crystal oligomer, and a liquid crystal polymer by irradiation with light.

[0090] For example, the first phase difference layer 120 can be formed by at least one resin selected from the following: cellulose resin, including triacetyl cellulose (TAC), polyester resin, including polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate (PEN), polybutylene naphthalate, etc., cyclic polyolefin (COP) resin, polycarbonate resin, polyether sulfone resin, polysulfone resin, polyamide resin, polyimide resin, polyolefin resin, polyarylate resin, polyvinyl alcohol resin, polyvinyl chloride resin and polyvinylidene chloride resin. Preferably, the first phase difference layer 120 includes a cyclic polyolefin film to ensure short wavelength dispersion and long wavelength dispersion. In the polarizing plate according to the present invention, the cyclic polyolefin (COP) film can effectively improve the front reflectivity.

[0091] In one embodiment, the first phase difference layer 120 may include a film formed of a resin having positive (+) birefringence.

[0092] The first phase difference layer 120 may have a thickness of 60 μm or less, specifically about 10 μm to about 60 μm, and more specifically about 20 μm to about 50 μm. Within this range, the first phase difference layer 120 may be used in a polarizing plate.

[0093] The first phase difference layer 120 may be formed by stretching an unstretched film formed of an optically transparent resin, and may be stacked on a polarizer to manufacture a polarizing plate through a roll-to-roll process, thereby improving workability.

[0094] In one embodiment, the first phase difference layer 120 is formed by tilting and stretching a film in an unstretched state at a predetermined angle relative to the machine direction of the film, and it can ensure a slow axis tilted relative to the machine direction of the film. The method of tilting and stretching the film can be implemented by a typical method known to those skilled in the art.

[0095] For the first phase difference layer formed by the obliquely stretched film, the slow axis of the first phase difference layer can be tilted at a predetermined angle relative to the transmission axis of the polarizer, so that the polarizing plate can reduce the reflectivity of both the front and side surfaces of the screen while improving the ellipticity of the side surfaces. The transmission axis of the polarizer corresponds to the transverse direction (TD) of the polarizer.

[0096] refer to Figure 2, the slow axis 120a of the first phase difference layer 120 is inclined at an angle α1 of about +55° to about +80° (e.g., +55°, +60°, +65°, +70°, +75°, or +80°) relative to the transmission axis 110a of the polarizer 110, or at an angle α1 of about -80° to about -55° (e.g., -80°, -75°, -70°, -65°, -60°, or -55°). Within this range, the angle defined between the slow axis of the first phase difference layer and the slow axis of the second phase difference layer can be within a predetermined range, so that the polarizing plate can reduce the front and side reflectivity while ensuring an ellipticity of about 65% or more at an incident angle of about 60°. Preferably, the angle α1 is in the range of about +62° to about +75°, or in the range of about -75° to about -62°, more preferably, in the range of about +64° to about +70°, or in the range of about -70° to about -64°.

[0097] Despite Figure 1 It is not shown in the figure, but the first phase difference layer 120 can be bonded to the polarizer 110 by a first bonding layer. The first bonding layer can be formed by (for example) a water-based adhesive and / or a photocurable adhesive. Preferably, the first bonding layer is formed by a photocurable adhesive, so that the bonding between the protective film and the polarizer and the bonding between the polarizer and the first phase difference layer can be achieved by light exposure once, thereby improving the processability of the polarizing plate. The first bonding layer can have a thickness of about 0.1 μm to about 10 μm, specifically about 0.5 μm to about 5 μm. Within this range, the bonding layer can be used in a polarizing plate.

[0098] Second phase difference layer

[0099] The second phase difference layer 130 may have an in-plane phase difference of about 80nm to about 100nm at a wavelength of about 550nm. Through this structure, in combination with the first phase difference layer, the second phase difference layer can achieve a significant reduction in reflectivity on both the front and side surfaces while ensuring an ellipticity of about 65% or more at an incident angle of about 60°. Preferably, the second phase difference layer 130 has an in-plane phase difference of about 90nm to about 95nm at a wavelength of about 550nm. In one embodiment, the second phase difference layer may be a 1 / 6 phase difference layer at a wavelength of about 550nm.

[0100] The second phase difference layer 130 exhibits positive dispersion and may have a short wavelength dispersion of about 1 to about 1.1 and a long wavelength dispersion of about 0.96 to about 1. Preferably, the second phase difference layer has a short wavelength dispersion of about 1 to about 1.06 and a long wavelength dispersion of about 0.97 to about 1.

[0101] The second phase difference layer 130 may have an out-of-plane phase difference (Rth) of about -100 nm to about -50 nm (e.g., -100 nm, -90 nm, -80 nm, -70 nm, -60 nm, or -50 nm) at a wavelength of about 550 nm, preferably greater than about -100 nm to -50 nm, about -70 nm to about -50 nm, or about -70 nm to about -60 nm. Within this range, the second phase difference layer 130 may reduce the lateral reflectivity relative to the side by improving the ellipticity.

[0102] The second phase difference layer 130 may have a biaxiality of about -0.5 to about -0.2 (e.g., -0.5, -0.4, -0.3 or -0.2), preferably about -0.4 to about -0.2, and more preferably about -0.3 to about -0.2 at a wavelength of about 550 nm. Within this range, the second phase difference layer 130 may reduce the lateral reflectivity by improving the ellipticity relative to the side.

[0103] The second phase difference layer 130 may have a refractive index of about 1.4 to about 1.6, preferably about 1.5 to about 1.6. Within this range, the second phase difference layer 130 enables control of the refractive index relative to the first phase difference layer, thereby improving transparency.

[0104] The second phase difference layer 130 is formed of a composition of the second phase difference layer as described below. In this article, the second phase difference layer can be formed so that the slow axis of the second phase difference layer can be tilted at an angle within a predetermined range relative to the transmission axis of the polarizer by controlling the coating direction and / or coating method, so that the polarizing plate can reduce the front and side reflectivity while improving the ellipticity of the side.

[0105] For the polarizing plate according to the present invention, the first phase difference layer 120 and the second phase difference layer 130 may satisfy at least one of the following relationships ① to ⑧:

[0106] ① When 0°<θ[fast axis-absorption axis of the first phase difference layer]<90°,

[0107] θ[fast axis-absorption axis of the second phase difference layer]=θ[fast axis-absorption axis of the first phase difference layer]×2+45+α, 4°≤α≤6°;

[0108] ②-90°<θ[slow axis-absorption axis of the first phase difference layer]<0°,

[0109] θ[slow axis - absorption axis of the second phase difference layer] = θ[slow axis - absorption axis of the first phase difference layer] × 2-45 + α, 4°≤α≤6°;

[0110] ③When -90°<θ[fast axis-absorption axis of the first phase difference layer]<0°,

[0111] θ[fast axis-absorption axis of the second phase difference layer]=θ[fast axis-absorption axis of the first phase difference layer]×2-45-α, 4°≤α≤6°; and

[0112] ④ When 0°<θ[slow axis-absorption axis of the first phase difference layer]<90°,

[0113] θ[slow axis - absorption axis of the second phase difference layer] = θ[slow axis - absorption axis of the first phase difference layer] × 2-45-α, 4°≤α≤6°,

[0114] (In ①, ②, ③ and ④,

[0115] θ[fast axis - absorption axis of the first retardation layer] is the angle of the fast axis of the first retardation layer relative to the absorption axis of the polarizer (unit: °),

[0116] θ[slow axis of the first retardation layer - absorption axis] is the angle of the slow axis of the first retardation layer relative to the absorption axis of the polarizer (unit: °),

[0117] θ[fast axis - absorption axis of the second retardation layer] is the angle of the fast axis of the second retardation layer relative to the absorption axis of the polarizer (unit: °), and

[0118] θ[slow axis of the second retardation layer - absorption axis] is the angle of the slow axis of the second retardation layer relative to the absorption axis of the polarizer (unit: °);

[0119] ⑤When 0°<θ[slow axis-transmission axis of the first phase difference layer]<90°,

[0120] θ[slow axis - transmission axis of the second phase difference layer] = θ[slow axis - transmission axis of the first phase difference layer] × 2 + 45 + α, 4° ≤ α ≤ 6°;

[0121] ⑥ When -90°<θ[fast axis-transmission axis of the first phase difference layer]<0°,

[0122] θ[fast axis - transmission axis of the second phase difference layer] = θ[fast axis - transmission axis of the first phase difference layer] × 2-45 + α, 4°≤α≤6°;

[0123] ⑦ When -90°<θ[slow axis-transmission axis of the first phase difference layer]<0°,

[0124] θ[slow axis - transmission axis of the second phase difference layer] = θ[slow axis - transmission axis of the first phase difference layer] × 2-45-α, 4°≤α≤6°; and

[0125] ⑧When 0°<θ[fast axis-transmission axis of the first phase difference layer]<90°,

[0126] θ[fast axis - transmission axis of the second phase difference layer] = θ[fast axis - transmission axis of the first phase difference layer] × 2-45-α, 4°≤α≤6°,

[0127] (In ⑤, ⑥, ⑦ and ⑧,

[0128] θ[fast axis of the first retardation layer - transmission axis] is the angle of the fast axis of the first retardation layer relative to the transmission axis of the polarizer (unit: °),

[0129] θ[slow axis of the first retardation layer - transmission axis] is the angle of the slow axis of the first retardation layer relative to the transmission axis of the polarizer (unit: °),

[0130] θ[fast axis of the second retardation layer - transmission axis] is the angle of the fast axis of the second retardation layer relative to the transmission axis of the polarizer (unit: °), and

[0131] θ[slow axis of the second retardation layer - transmission axis] is the angle (unit: °) of the slow axis of the second retardation layer relative to the transmission axis of the polarizer.

[0132] In relations ① to ⑧, when the calculated value is 180° or more in the calculation of the angle defined in ① to ⑧, the final value is obtained by subtracting 180° from the calculated value. For example, in ⑤, when θ[slow axis-transmission axis of the first phase difference layer] is 68°, when the angle α is 6°, the calculated value is 187°, and θ[slow axis-transmission axis of the second phase difference layer] is calculated to be 7°. That is, θ[slow axis-transmission axis of the second phase difference layer] can be calculated as θ[slow axis-transmission axis of the first phase difference layer]×2+45+α-180°.

[0133] By satisfying at least one of the relationships ① to ⑧, the polarizing plate can reduce the front and side reflectivity while ensuring a side ellipticity of about 65% or more, specifically, at an incident angle of about 60°, thereby significantly improving the screen quality by being applied to optical display devices.

[0134] refer to Figure 2 , relative to the transmission axis 110a of the polarizer 110, the slow axis 130a of the second phase difference layer 130 is inclined at an angle α2 of about 0° to about +10°, or at an angle of about -10° to about 0°. Within this range, the polarizing plate can reduce the front and side reflectivity. Preferably, the angle α2 can be in the range of about +6° to about +8° or about -8° to about -6°.

[0135] In one embodiment, the angle defined between the slow axis 120a of the first phase difference layer 120 and the slow axis 130a of the second phase difference layer 130 may be in the range of about 55° to about 80° (e.g., 55°, 60°, 65°, 70°, 75°, or 80°), preferably about 60° to about 75°, more preferably about 60° to about 65°. Within this range, the polarizing plate can reduce the reflectivity on the inclined surface.

[0136] The second phase difference layer 130 may have a thickness of 20 μm or less, preferably about 1 μm to 20 μm, more preferably about 2 μm to 10 μm, and most preferably about 2 μm to about 8 μm. Within this range, the second phase difference layer can effectively show excellent out-of-plane phase difference (Rth) over its entire width and enable the thickness of the polarizing plate to be reduced.

[0137] Hereinafter, the composition of the second phase difference layer will be described.

[0138] The second phase difference layer may be a non-liquid crystal layer. For the second phase difference layer including liquid crystal, it is necessary to provide the polarizing plate with an alignment film for aligning the liquid crystal at a specific angle, thereby causing the generation of exogenous substances. Therefore, the polarizing plate according to the present invention may not include an alignment layer.

[0139] In one embodiment, the composition of the second phase difference layer is a non-liquid crystal composition and may include a coating layer, preferably a stretched coating layer, comprising a cellulose ester polymer and / or an aromatic compound. The cellulose ester polymer and / or the aromatic compound may achieve negative (-) birefringence.

[0140] Next, the cellulose ester polymer will be described.

[0141] As used herein, "polymer" means an oligomer, a polymer or a resin.

[0142] The cellulose ester polymer may include an ester polymer having an acyl unit, wherein at least some of the hydroxyl groups [C2 hydroxyl group, C3 hydroxyl group, or C6 hydroxyl group] of the sugar monomer constituting the cellulose are unsubstituted or substituted, as represented by Formula 1:

[0143]

[0144] Where n is an integer of 1 or more

[0145] The substituent groups of the cellulose ester polymer or the acyl unit may include at least one selected from the following: a halogen atom, a nitro group, an alkyl group (e.g., C1 to C 20 alkyl), alkenyl (e.g., C2 to C 20 alkenyl), cycloalkyl (e.g., C3 to C 10 Cycloalkyl), aryl (e.g., C6 to C 20aryl), heteroaryl (e.g., C3 to C 10 Aryl), alkoxy (e.g., C1 to C 20 The substituent groups may be the same or different from each other.

[0146] In the present invention, the term "acyl" may refer to RC(=O)-* (* is the attachment site, R is C1 to C 20 Alkyl, C3 to C 20 Cycloalkyl, C6 to C 20 Aryl or C7 to C 20 The term "acyl" refers to an acyl group (eg, an arylalkyl group) which is also known in the art. An "acyl group" is coupled to the cellulose ring through an ester bond (through an oxygen atom) in cellulose.

[0147] Herein, for convenience, "alkyl", "alkenyl", "cycloalkyl", "aryl", "heteroaryl", "alkoxy" and "acyl" represent non-halogen compounds. The composition of the second phase difference layer may include a single cellulose ester polymer or a mixture including a cellulose ester polymer.

[0148] In this context, "halogen" means fluorine (F), Cl, Br or I, preferably F.

[0149] A "halogen-containing functional group" is an organic functional group containing at least one halogen atom and may include aromatic, aliphatic or alicyclic functional groups. For example, a halogen-containing functional group may represent a halogen-substituted C1 to C 20 Alkyl, halogen-substituted C2 to C 20 Alkenyl, halogen-substituted C2 to C 20 Alkynyl, halogen-substituted C3 to C 10 Cycloalkyl, halogen-substituted C1 to C 20 Alkoxy, halogen-substituted acyl, halogen-substituted C6 to C 20 Aryl or halogen-substituted C7 to C 20 Arylalkyl, but not limited thereto.

[0150] "Halogen-substituted acyl" may be R'-C(=O)-* (* is the attachment site, R' is a halogen-substituted C1 to C 20 Alkyl, halogen-substituted C3 to C 20 Cycloalkyl, halogen-substituted C6 to C 20 Aryl or halogen-substituted C7 to C 20 "Halogen-substituted acyl" can be coupled to the cellulose ring via an ester bond (via an oxygen atom) in cellulose.

[0151] Preferably, the composition of the second phase difference layer includes a cellulose ester polymer substituted with a halogen or a halogen-containing functional group. More preferably, the halogen is fluorine. The halogen may be present in the cellulose ester polymer in an amount of 1 wt % to 10 wt %. Within this range, the composition enables easy formation of a second phase difference layer having the properties of the present invention.

[0152] For the formation of the second phase difference layer, a cellulose ester polymer can be prepared by a typical method known to those skilled in the art or can be obtained from a commercially available product. For example, a cellulose ester polymer having an acyl group as a substituent group can be prepared by reacting trifluoroacetic acid or trifluoroacetic anhydride with a sugar monomer or a polymer of sugar monomers constituting cellulose represented by Chemical Formula 1, by reacting trifluoroacetic acid or trifluoroacetic anhydride therewith, and then additionally reacting an acylating agent (e.g., carboxylic anhydride or carboxylic acid) therewith, or by reacting both trifluoroacetic acid or trifluoroacetic anhydride and an acylating agent therewith.

[0153] The aromatic compound may include a phenyl group and may include a polystyrene compound or a fluorobenzene or difluorostyrene structure, but is not limited thereto. In one embodiment, the polystyrene compound may include a moiety represented by Formula 2:

[0154]

[0155] in is the attachment site of the atom,

[0156] R 1 , R 2 and R 3 are independently a hydrogen atom, an alkyl group, a substituted alkyl group or a halogen;

[0157] Rs are each independently a substituent group on the styrene ring; and

[0158] n is an integer from 0 to 5, which indicates the number of substituent groups on the styrene ring.

[0159] Examples of the substituent group R on the styrene ring may include an alkyl group, a substituted alkyl group, a halogen atom, a hydroxyl group, a carboxyl group, a nitro group, an alkoxy group, an amino group, a sulfonate group, a phosphate group, an acyl group, an acyloxy group, a phenyl group, an alkoxycarbonyl group, and a cyano group.

[0160] In one embodiment, R 1 , R 2 and R 3 At least one of may be a halogen, preferably fluorine.

[0161] In addition to the cellulose ester polymer and the aromatic compound, the composition of the second phase difference layer may also include an additive containing an aromatic condensed ring. The additive containing an aromatic condensed ring is used to adjust the wavelength dispersion. Examples of additives containing aromatic condensed rings may include 2-naphthyl benzoate, anthracene, phenanthrene, 2,6-naphthalene dicarboxyl diester, and the like. The additive containing an aromatic condensed ring may be present in the composition of the second phase difference layer in an amount of 0.1wt% to 30wt%, preferably 1wt% to 10wt%. Within this range, the additive containing an aromatic condensed ring can adjust the phase difference and wavelength dispersion.

[0162] The composition of the second phase difference layer may further include typical additives known to those skilled in the art. The additives may include pigments and antioxidants, but are not limited thereto.

[0163] Despite Figure 2 Although not shown, an adhesive layer or a bonding layer may be formed on the lower surface of the second phase difference layer 130 to enable the polarizing plate to be stacked on an optical display device, for example, a light emitting diode panel.

[0164] Laminated structure of first retardation layer and second retardation layer

[0165] The laminate of the first phase difference layer and the second phase difference layer can have an in-plane phase difference of about 140 nm to about 190 nm (for example, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm or 190 nm), preferably about 150 nm to about 170 nm at a wavelength of about 550 nm. Within this range, the polarizing plate can reduce reflectivity while improving ellipticity.

[0166] In one embodiment, the first phase difference layer and the second phase difference layer laminate can be formed by coating the composition of the second phase difference layer on the first phase difference layer and then stretching the coating. Specifically, the second phase difference layer coating can be formed by coating the composition of the second phase difference layer on an unstretched or obliquely stretched film of the first phase difference layer and then stretching the coating in the MD direction of the first phase difference layer to form a laminate of the first phase difference layer and the second phase difference layer.

[0167] In another embodiment, a laminate of the first phase difference layer and the second phase difference layer may be formed by adhering the first phase difference layer to the second phase difference layer through an adhesive (for example, a pressure sensitive adhesive (PSA)).

[0168] Polarizer

[0169] The polarizer 110 is used to convert natural light or polarized light into polarized light by linear polarization in a specific direction, and can be produced from a polymer film mainly containing a polyvinyl alcohol resin. Specifically, the polarizer 130 can be produced by dyeing the polymer film with iodine or a dichroic dye and then stretching the film in MD. Specifically, the polarizer can be produced by expansion, dyeing, stretching, and cross-linking.

[0170] The polarizer 110 may have a total transmittance of 40% or more, for example, 40% to 47%, and a polarization degree of 99% or more, for example, 99% to 100%. Within this range, the polarizer may improve the anti-reflection performance of the polarizing plate by combining with the first phase difference layer and the second phase difference layer.

[0171] The polarizer 110 may have a thickness of about 2 μm to about 30 μm, specifically about 4 μm to about 25 μm. Within this range, the polarizer may be used in a polarizing plate.

[0172] Protective film

[0173] The protective film 150 is formed on the upper surface of the polarizer 110 to protect the polarizer against the external environment while improving the mechanical strength of the polarizing plate. However, it should be noted that the protective film 140 may be omitted if its omission does not affect the mechanical strength properties of the polarizing plate.

[0174] The protective film 140 is used to protect the polarizer against the external environment and can be an optically transparent film formed of at least one resin selected from the following: cellulose resin, including triacetyl cellulose (TAC), etc., polyester resin, including polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate (PEN), polybutylene naphthalate, etc., cyclic polyolefin resin, polycarbonate resin, polyether sulfone resin, polysulfone resin, polyamide resin, polyimide resin, polyolefin resin, polyarylate resin, polyvinyl alcohol resin, polyvinyl chloride resin and polyvinylidene chloride resin. Specifically, the protective film can be a TAC film or a PET film.

[0175] The protective film 140 may have a thickness of about 5 μm to about 70 μm, specifically about 15 μm to about 45 μm. Within this range, the protective film may be used in a polarizing plate.

[0176] Despite Figure 1 Although not shown in the figure, a functional coating may be further formed on the upper surface of the protective film 140 to provide other functions for the polarizing plate. For example, the functional coating may include a hard coating, an anti-fingerprint layer, an anti-reflection layer, an anti-glare layer, etc. These functional coatings may be stacked alone or in combination.

[0177] Despite Figure 1 Although not shown in the figure, the protective film 140 may be bonded to the polarizer 110 via a second bonding layer. The second bonding layer may be formed of a water-based adhesive and / or a photocurable adhesive. Preferably, the second bonding layer is formed of a photocurable adhesive, so that the bonding between the protective film and the polarizer and the bonding between the polarizer and the first phase difference layer can be achieved once by irradiation with light, thereby improving the processability of the polarizing plate.

[0178] In one embodiment, the photocurable adhesive may be formed from the composition of the first adhesive layer. In one embodiment, the composition may include a photoinitiator that has an absorption function for light having a wavelength of about 300 nm to about 400 nm and is used to cause a reaction upon irradiation with light. The photoinitiator may include a light-radical photoinitiator and / or a cationic photoinitiator.

[0179] The second adhesive layer may have a thickness of about 0.1 μm to about 10 μm, specifically about 0.5 μm to about 5 μm. Within this range, the second adhesive layer may be used in a polarizing plate.

[0180] Next, a polarizing plate according to another embodiment of the present invention will be described.

[0181] The polarizing plate according to this embodiment includes a polarizer, a protective film stacked on the upper surface of the polarizer, and a first phase difference layer and a second phase difference layer sequentially stacked on the lower surface of the polarizer, wherein the first phase difference layer may have an in-plane phase difference of about 180nm to about 220nm at a wavelength of about 550nm; and the second phase difference layer may have an in-plane phase difference of about 80nm to about 100nm at a wavelength of about 550nm. The polarizing plate may also include a third phase difference layer.

[0182] In one embodiment, the third phase difference layer may be inserted between the polarizer and the first phase difference layer.

[0183] The third phase difference layer may include a positive C phase difference layer, which satisfies nz>nx≒ny (nx, ny and nz are the refractive indices of the third phase difference layer in its slow axis direction, fast axis direction and thickness direction respectively at a wavelength of 550nm).

[0184] In one embodiment, the third phase difference layer may have an out-of-plane phase difference (Rth) of about -300nm to about 0nm, for example, about -80nm to about 0nm (for example, -80nm, -70nm, -60nm, -50nm, -40nm, -30nm, -20nm, -10nm or 0), about -80nm to about -20nm, or about -40nm to about -30nm at a wavelength of about 550nm. The third phase difference layer may have an in-plane phase difference of about 0nm to about 10nm, for example, about 0nm to 5nm at a wavelength of about 550nm. Within this range, the polarizing plate can achieve a reduced reflectivity.

[0185] In one embodiment, the third phase difference layer may be a liquid crystal layer. The liquid crystal layer may be formed of a well-known typical material to achieve the above-mentioned out-of-plane phase difference.

[0186] In another embodiment, the third phase difference layer may be formed of the composition of the second phase difference layer as described above.

[0187] The optical display device according to the present invention may include the polarizing plate according to the embodiment of the present invention. For example, the optical display device may include an organic light emitting diode (OLED) display and a liquid crystal display.

[0188] In one embodiment, an OLED display device may include: an OLED panel including a flexible substrate; and a polarizing plate according to the present invention stacked on the OLED panel.

[0189] In another embodiment, an OLED display device may include: an OLED panel including a non-flexible substrate; and a polarizing plate according to the present invention stacked on the OLED panel.

[0190] Then, the present invention will be described in more detail with reference to some examples. However, it should be noted that these examples are provided for illustration only and should not be regarded as limiting the present invention in any way.

[0191] Example 1

[0192] A polyvinyl alcohol film (PS#60, pre-stretched thickness: 60 μm, Kuraray Co., Ltd.) was stretched to 6 times its original length in an iodine aqueous solution at 55° C., thereby preparing a polarizer having a transmittance of 45%.

[0193] The coating layer of the second phase difference layer was formed by depositing a composition of the second phase difference layer [a non-crystalline composition comprising a cellulose ester polymer (including a trifluoroacetyl group) containing 5 wt% of fluorine therein] on the lower surface of a cyclic polyolefin (COP) film (ZD film, Zeon Co., Ltd.). The cellulose ester polymer was prepared by adding trifluoroacetic acid and trifluoroacetic anhydride to unsubstituted cellulose, followed by reaction and polymerization.

[0194] After the coating was dried, the laminate of the coating and the COP film was stretched to 1.7 times its original length at 110°C and at an angle of 45° relative to the MD of the COP film, thereby preparing a laminate of a first phase difference layer (flat dispersion) and a second phase difference layer (positive dispersion) having the technical specifications listed in Table 1.

[0195] With HC-TAC film (25FJCHCN-TC, thickness: 32 μm, Toppan) stacked as a protective film on the upper surface of the polarizer, a laminate of a first phase difference layer (thickness: 37 μm) and a second phase difference layer (thickness: 3 μm) was attached to the lower surface of the polarizer, thereby providing a polarizing plate.

[0196] Examples 2 to 5

[0197] A polarizing plate was manufactured in the same manner as in Example 1, except that the phase difference of each of the first and second phase difference layers was changed by changing the elongation and stretching temperature as listed in Table 1.

[0198] Examples 6 to 9

[0199] A polarizing plate was manufactured in the same manner as in Example 1, except that a positive C-plate phase difference layer (a third phase difference layer formed of a cellulose ester composition) having an Rth (@550nm) as listed in Table 1 was additionally stacked between the polarizer and the first phase difference layer, and the characteristics of each of the first phase difference layer and the second phase difference layer were maintained or changed as listed in Table 1.

[0200] Comparative Examples 1 to 4

[0201] A polarizing plate was manufactured in the same manner as in Example 1, except that the phase difference of each of the first and second phase difference layers was changed by changing the elongation and stretching temperature as listed in Table 1.

[0202] The phase difference Re, Rth, and NZ of each of the first and second phase difference layers at a wavelength of 550 nm were measured using an AxoScan polarimeter (AxoMetric Co., Ltd.).

[0203] Each polarizing plate manufactured in the examples and comparative examples was evaluated for the following properties. The results are shown in Table 1

[0204] (1) Reflectivity (unit: %): The reflectivity was measured by parameterizing each layer in the polarizing plate, assuming total reflection, using an extended Jones matrix calculation method. In this paper, the primary reflection of the outermost layer was excluded from the calculation.

[0205] (2) Ellipticity (unit: %): The ellipticity was measured at each azimuth angle of 1° by parameterizing each layer in the polarizing plate by allowing natural light to pass through the polarizer, the first phase difference layer, and the second phase difference layer of the polarizing plate in sequence at an incident angle (60°). The minimum value of the ellipticity is shown in Table 1.

[0206] Table 1

[0207]

[0208] *Angle 1: The angle between the slow axis of the first phase difference layer and the transmission axis of the polarizer

[0209] *Angle 2: The angle between the slow axis of the second phase difference layer and the transmission axis of the polarizer

[0210] As shown in Table 1, the polarizing plate according to the present invention has low reflectivity at both the front and side surfaces and has an ellipticity of about 65% or more at an incident angle of 60°, thereby improving screen quality (minimizing color changes at an incident angle of 60° and an azimuth angle of 0° to 360°). In addition, the effects of the polarizing plates of Examples 6 to 9, each including a positive C plate, are better than those of the polarizing plates of Examples 1 to 5, each not including a positive C plate.

[0211] In contrast, the polarizing plates of Comparative Examples 1 to 4 including the first phase difference layer and the second phase difference layer, each having an in-plane phase difference in the in-plane phase difference according to the present invention, have a reflectivity higher than that of the polarizing plate of the embodiment on both the front and side surfaces and cannot achieve an ellipticity of about 65% or more at an incident angle of 60°.

[0212] It will be appreciated by those skilled in the art that numerous modifications, changes, variations and equivalent embodiments may be made without departing from the spirit and scope of the present invention.

Claims

1. A polarizing plate, comprising: Polarizer; and a first phase difference layer and a second phase difference layer sequentially stacked on a lower surface of the polarizer, wherein the first phase difference layer has an in-plane phase difference of 180 nm to 220 nm at a wavelength of 550 nm; and The second phase difference layer has an in-plane phase difference of 80 nm to 100 nm at a wavelength of 550 nm. wherein the first phase difference layer exhibits positive dispersion or flat dispersion, and the second phase difference layer exhibits positive dispersion, The second phase difference layer has a biaxiality NZ of -0.5 to -0.

2. 2 . The polarizing plate according to claim 1 , wherein the first phase difference layer is a 1 / 3 phase difference layer at a wavelength of 550 nm, and the second phase difference layer is a 1 / 6 phase difference layer at a wavelength of 550 nm. 3 . The polarizing plate according to claim 1 , wherein the first phase difference layer has a slow axis tilted at an angle of +55° to +80° or at an angle of −80° to −55° with respect to a transmission axis of the polarizer. 4 . The polarizing plate according to claim 1 , wherein the second phase difference layer has a slow axis tilted at an angle of 0° to +10° or at an angle of −10° to 0° with respect to a transmission axis of the polarizer.

5. The polarizing plate according to claim 1, wherein the first phase difference layer and the second phase difference layer satisfy at least one of the following relationships ① to ⑧: ① When 0°<θ[fast axis-absorption axis of the first phase difference layer]<90°, θ[fast axis-absorption axis of the second phase difference layer]=θ[fast axis-absorption axis of the first phase difference layer]×2+45+α, 4°≤α≤6°; ②-90°<θ[slow axis-absorption axis of the first phase difference layer]<0°, θ[slow axis-absorption axis of the second phase difference layer]=θ[slow axis-absorption axis of the first phase difference layer]×2-45+α, 4°≤α≤6°; ③When -90°<θ[fast axis-absorption axis of the first phase difference layer]<0°, θ[fast axis-absorption axis of the second phase difference layer]=θ[fast axis-absorption axis of the first phase difference layer]×2-45-α, 4°≤α≤6°; and ④ When 0°<θ[slow axis-absorption axis of the first phase difference layer]<90°, θ[slow axis - absorption axis of the second phase difference layer] = θ[slow axis - absorption axis of the first phase difference layer] × 2-45-α, 4°≤α≤6°, Among ①, ②, ③ and ④, θ[fast axis - absorption axis of the first phase difference layer] is the angle of the fast axis of the first phase difference layer relative to the absorption axis of the polarizer, and its unit is °. θ[slow axis of the first phase difference layer - absorption axis] is the angle of the slow axis of the first phase difference layer relative to the absorption axis of the polarizer, and its unit is °. θ[fast axis of the second retardation layer - absorption axis] is the angle of the fast axis of the second retardation layer relative to the absorption axis of the polarizer, and its unit is °, and θ[slow axis of the second phase difference layer - absorption axis] is the angle of the slow axis of the second phase difference layer relative to the absorption axis of the polarizer, and its unit is °; ⑤ When 0°<θ[slow axis-transmission axis of the first phase difference layer]<90°, θ[slow axis-transmission axis of the second phase difference layer]=θ[slow axis-transmission axis of the first phase difference layer]×2+45+α, 4°≤α≤6°; ⑥ When -90°<θ[fast axis - transmission axis of the first phase difference layer]<0°, θ[fast axis - transmission axis of the second phase difference layer]=θ[fast axis - transmission axis of the first phase difference layer]×2-45+α, 4°≤α≤6°; ⑦ When -90°<θ[slow axis-transmission axis of the first phase difference layer]<0°, θ[slow axis-transmission axis of the second phase difference layer]=θ[slow axis-transmission axis of the first phase difference layer]×2-45-α, 4°≤α≤6°; ⑧ When 0°<θ[fast axis-transmission axis of the first phase difference layer]<90°, θ[fast axis-transmission axis of the second phase difference layer]=θ[fast axis-transmission axis of the first phase difference layer]×2-45-α, 4°≤α≤6°, In ⑤, ⑥, ⑦ and ⑧, θ[fast axis of the first phase difference layer - transmission axis] is the angle of the fast axis of the first phase difference layer relative to the transmission axis of the polarizer, and its unit is °. θ[slow axis of the first phase difference layer - transmission axis] is the angle of the slow axis of the first phase difference layer relative to the transmission axis of the polarizer, and its unit is °. θ[fast axis of the second retardation layer - transmission axis] is the angle of the fast axis of the second retardation layer relative to the transmission axis of the polarizer, and its unit is °, and θ[slow axis of the second retardation layer−transmission axis] is the angle of the slow axis of the second retardation layer relative to the transmission axis of the polarizer, and its unit is degrees. 6 . The polarizing plate according to claim 1 , wherein an angle defined between a slow axis of the first phase difference layer and a slow axis of the second phase difference layer is in a range of 55° to 80°. 7 . The polarizing plate according to claim 1 , wherein a laminate of the first phase difference layer and the second phase difference layer has an in-plane phase difference of 140 nm to 190 nm at a wavelength of 550 nm. 8 . The polarizing plate according to claim 1 , wherein the first phase difference layer has an out-of-plane phase difference Rth of 100 nm to 150 nm at a wavelength of 550 nm. 9 . The polarizing plate according to claim 1 , wherein the first phase difference layer has a biaxiality NZ of 1.1 to 1.2 at a wavelength of 550 nm. 10 . The polarizing plate according to claim 1 , wherein the second phase difference layer has an out-of-plane phase difference Rth of −100 nm to −50 nm at a wavelength of 550 nm. 11 . The polarizing plate according to claim 1 , wherein the first phase difference layer comprises a film formed of a resin having positive (+) birefringence. 12 . The polarizing plate according to claim 1 , wherein the second phase difference layer comprises a coating layer formed by stretching a film formed of at least one selected from a cellulose ester resin and an aromatic resin.

13. The polarizing plate according to claim 1, further comprising: A third phase difference layer includes a positive C plate having an out-of-plane phase difference Rth of -300 nm to 0 nm at a wavelength of 550 nm. 14 . The polarizing plate according to claim 13 , wherein the third phase difference layer has an out-of-plane phase difference Rth of −80 nm to −20 nm at a wavelength of 550 nm. 15 . The polarizing plate according to claim 13 , wherein the third phase difference layer is interposed between the polarizer and the first phase difference layer.

16. The polarizing plate according to claim 1, further comprising: A protective layer is formed on an upper surface of the polarizer. 17 . An optical display device comprising the polarizing plate according to claim 1 .

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