Polarizing plate and optical display apparatus comprising the same
A polarizing plate and an optical display apparatus including the same are provided. The polarizing plate includes: a polarizer; and a first retardation layer and a second retardation layer sequentially stacked on a lower surface of the polarizer. The first retardation layer has an in-plane retardation (Re) of 200 nm to 250 nm at a wavelength of 550 nm; the second retardation layer has an in-plane retardation (Re) of 80 nm to 140 nm at a wavelength of 550 nm; and the polarizing plate has a total transmittance difference of 2% or more between total transmittance at a wavelength of 450 nm and total transmittance at a wavelength of 420 nm.
1. A polarizing plate comprising:
a polarizer; and
a first retardation layer and a second retardation layer sequentially stacked on a lower surface of the polarizer, wherein:
the first retardation layer has an in-plane retardation (Re) of 200 nm to 250 nm at a wavelength of 550 nm;
the second retardation layer has an in-plane retardation (Re) of 80 nm to 140 nm at a wavelength of 550 nm; and
the polarizing plate has a total transmittance difference of 2% or more between a total transmittance at a wavelength of 450 nm and a total transmittance at a wavelength of 420 nm,
wherein the first retardation layer comprises a resin having a positive (+) birefringence and the second retardation layer comprises a resin having a negative (−) birefringence.
2. The polarizing plate according to claim 1 , wherein the polarizing plate has the total transmittance of 30% or more at the wavelength of 450 nm and the total transmittance of 40% or less at the wavelength of 420 nm.
3. The polarizing plate according to claim 1 , wherein the polarizing plate has a total transmittance of 2% or less at a wavelength of 380 nm.
4. The polarizing plate according to claim 1 , wherein the first retardation layer has an out-of-plane retardation of 95 nm to 200 nm and a degree of biaxiality of 1 to 1.5, at the wavelength of 550 nm.
5. The polarizing plate according to claim 1 , wherein each of the first retardation layer and the second retardation layer is a non-liquid crystal layer.
6. The polarizing plate according to claim 1 , wherein the second retardation layer comprises at least one selected from among a cellulose ester polymer and a polystyrene polymer.
7. The polarizing plate according to claim 1 , wherein a laminate of the first retardation layer and the second retardation layer has a total transmittance of 90% or more at a wavelength of 420 nm to 450 nm.
8. The polarizing plate according to claim 1 , wherein the polarizer has a total transmittance of 40% to 45% at a wavelength of 380 nm to 780 nm.
9. The polarizing plate according to claim 1 , wherein the polarizer comprises 1 wt % to 5 wt % of potassium iodide.
10. The polarizing plate according to claim 1 , wherein an absolute value of a tilt angle of a slow axis of the first retardation layer with reference to a transmission axis of the polarizer is in a range of 50° to 80° and an absolute value of a tilt angle of a slow axis of the second retardation layer with reference to the transmission axis of the polarizer is in a range of 0° to 10°.
11. The polarizing plate according to claim 1 , wherein the polarizing plate further comprises a light absorbent.
12. The polarizing plate according to claim 11 , wherein the light absorbent has a maximum absorption wavelength of 330 nm to 380 nm.
13. The polarizing plate according to claim 1 , further comprising: a protective film on an upper surface of the polarizer.
14. An optical display apparatus comprising the polarizing plate according to claim 1 .
15. A polarizing plate comprising:
a polarizer; and
a first retardation laver and a second retardation laver sequentially stacked on a lower surface of the polarizer, wherein:
the first retardation layer has an in-plane retardation (Re) of 200 nm to 250 nm at a wavelength of 550 nm;
the second retardation laver has an in-plane retardation (Re) of 80 nm to 140 nm at a wavelength of 550 nm; and
the polarizing plate has a total transmittance difference of 2% or more between a total transmittance at a wavelength of 450 nm and a total transmittance at a wavelength of 420 nm,
wherein the second retardation layer has an out-of-plane retardation of −250 nm to −50 nm and a degree of biaxiality of −2 to −0.1, at the wavelength of 550 nm.