Polarizing plate and optical display device comprising same
Provided is a polarizing plate and an optical display device comprising same, the polarizing plate comprising: a polarizer; and a stack body of a first phase difference layer and a second phase difference layer stacked on a lower surface of the polarizer, wherein the first phase difference layer satisfies Equation 1, the second phase difference layer satisfies Equation 2, the sum of an in-plane phase difference at a wavelength of 550 nm between the first phase difference layer and the second phase difference layer is about 100 nm to about 110 nm, the sum of a thickness direction phase difference at a wavelength of 550 nm between the first phase difference layer and the second phase difference layer is about −30 nm to about +10 nm, and the second phase difference layer comprises a fluorine-based phase difference layer.
1. A polarizing plate comprising:
a polarizer; and
a laminate of a first retardation layer and a second retardation layer stacked on a lower surface of the polarizer,
wherein the first retardation layer satisfies Equation 1 and the second retardation layer satisfies Equation 2:
nx>ny>nz, [Equation 1]
wherein Equation 1, nx, ny and nz are indexes of refraction of the first retardation layer at a wavelength of 550 nm in a slow axis direction, a fast axis direction and a thickness direction thereof,
nz>nx>ny, [Equation 2]
wherein Equation 2, nx, ny and nz are indexes of refraction of the second retardation layer at a wavelength of 550 nm in a slow axis direction, a fast axis direction and a thickness direction thereof;
a sum of in-plane retardation values of the first retardation layer and the second retardation layer at a wavelength of 550 nm ranges from about 100 nm to about 110 nm,
a sum of out-of-plane retardation values of the first retardation layer and the second retardation layer at a wavelength of 550 nm ranges from about-30 nm to about +10 nm, and
the second retardation layer comprises a fluorene-based retardation layer.
2. The polarizing plate according to claim 1 , wherein the second retardation layer is directly formed on the first retardation layer.
3. The polarizing plate according to claim 1 , wherein the second retardation layer has a slow axis tilted at an angle of about−5° to about +5°, when that the first retardation layer has a slow axis disposed at an angle of 0°.
4. The polarizing plate according to claim 1 , wherein the second retardation layer has an in-plane retardation value of about 50 nm to about 60 nm and an out-of-plane retardation value of about −150 nm to about −120 nm at a wavelength of 550 nm.
5. The polarizing plate according to claim 1 , wherein the second retardation layer has a degree of biaxiality of about −3 to about 0 at a wavelength of 550 nm.
6. The polarizing plate according to claim 1 , wherein the second retardation layer satisfies relations: about 1.0≤Re(450)/Re(550)≤about 1.2 and about 0.85≤Re(650)/Re(550)≤about 1.0, where Re(450), Re(550), and Re(650) denote in-plane retardation values at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.
7. The polarizing plate according to claim 1 , wherein the second retardation layer has an nx value of about 1.59 to about 1.61, an ny value of about 1.59 to about 1.61, and an nz value of about 1.61 to about 1.63 in Equation 2.
8. The polarizing plate according to claim 1 , wherein the second retardation layer comprises a fluorene-based ring-containing resin and an aromatic thermoplastic resin.
9. The polarizing plate according to claim 1 , wherein the polarizer has a slow axis tilted at an angle of about 87° to about 93°, when that the polarizer has an absorption axis disposed at an angle of 0°.
10. The polarizing plate according to claim 1 , wherein the first retardation layer has an in-plane retardation value of about 50 nm to about 60 nm and an out-of-plane retardation value of about 120 nm to about 150 nm at a wavelength of 550 nm.
11. The polarizing plate according to claim 1 , wherein the first retardation layer satisfies relations: about 1.0≤Re(450)/Re(550)≤about 1.2 and about 0.85≤Re(650)/Re(550)≤about 1.0, where Re(450), Re(550), and Re(650) denote in-plane retardation values at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.
12. The polarizing plate according to claim 1 , wherein the first retardation layer comprises a cyclic olefin polymer film.
13. The polarizing plate according to claim 1 , wherein the first retardation layer has an nx value of about 1.50 to about 1.55, an ny value of about 1.48 to about 1.53, and an nz value of about 1.48 to about 1.53 in Equation 1.
14. The polarizing plate according to claim 1 , wherein the first retardation layer and the second retardation layer are sequentially stacked on the polarizer, or the second retardation layer and the first retardation layer are sequentially stacked on the polarizer.
15. The polarizing plate according to claim 1 , further comprising:
a protective film stacked on an upper surface of the polarizer.
16. An optical display apparatus comprising the polarizing plate according to claim 1 .
17. The optical display apparatus according to claim 16 , comprising:
a liquid crystal panel; and
the polarizing plate stacked on a light incidence surface of the liquid crystal panel.