Polarizing plate and optical display device including same
A polarizing plate and an optical display device comprising the same are disclosed. The polarizing plate includes a polarizer comprising a zinc cation and a unit represented by the Formula 1, and the polarizing plate has a chrominance variation ΔE of about 5.2 or less, as calculated by Equation 1.
1. A polarizing plate comprising a polarizer film,
the polarizer film comprises a zinc cation coupled to a unit represented by the following Formula 1:
where * is a linking site,
R is a hydrogen or a C 1 to C 5 alkyl group,
n is an integer of 10 to 100,000, and m is an integer of 0 to 10,
wherein the polarizing plate has a chrominance variation ΔE of 5.2 or less, as calculated by Equation 1:
Δ E =[(Δ L )+(Δ a *) 2 +(Δ b *) 2 ] 1/2 [Equation 1]
where ΔL is L 2 -L 1 ; Δa* is (a*) 2 −(a*) 1 ; and Δb* is (b*) 2 −(b*) 1 , in which L 1 is an L value of the polarizing plate before the polarizing plate is left at about 95° C. for about 500 hours; L 2 is an L value of the polarizing plate after the polarizing plate is left at about 95° C. for about 500 hours; (a*) 1 is an a* value of the polarizing plate before the polarizing plate is left at about 95° C. for about 500 hours; (a*) 2 is an a* value of the polarizing plate after the polarizing plate is left at about 95° C. for about 500 hours; (b*) 1 is a b* value of the polarizing plate before the polarizing plate is left at about 95° C. for about 500 hours; and (b*) 2 is a b* value of the polarizing plate after the polarizing plate is left at about 95° C. for about 500 hours, where the L value, the a* value, and the b* value indicate color space values according to CIE1976 and are measured using a spectrophotometer.
2. The polarizing plate according to claim 1 , wherein the zinc cation includes a zinc divalent cation.
3. The polarizing plate according to claim 1 , wherein the zinc cation is present in an amount of about 10 ppm to about 5,000 ppm in the polarizer.
4. The polarizing plate according to claim 1 , wherein the unit represented by the Formula 1 is present in an amount of more than about 0 wt % and about 35 wt % or less.
5. The polarizing plate according to claim 1 , wherein the polarizer film comprises a cross-linked product of an organic acid zinc salt.
6. The polarizing plate according to claim 5 , wherein the zinc cation coupled to the unit represented by the Formula 1 are derived from the cross-linked product of the organic acid zinc salt or the organic acid zinc salt.
7. The polarizing plate according to claim 5 , wherein the organic acid zinc salt comprises the zinc cation coupled to an organic acid anion represented by the following Formula 2:
CH 2 ═CR—(CH 2 ) m —(C═O)—O − [Formula 2]
where R is a hydrogen or a C 1 to C 5 alkyl group, and
m is an integer of 0 to 10.
8. The polarizing plate according to claim 5 , wherein the organic acid zinc salt comprises at least one of zinc (meth)acrylate and 10-undecenoic acid zinc salt.
9. The polarizing plate according to claim 5 , wherein the cross-linked product of the organic acid zinc salt comprises a UV cured product of the organic acid zinc salt.
10. The polarizing plate according to claim 1 , wherein the polarizer film comprises a photo-radical initiator.
11. The polarizing plate according to claim 1 , wherein the polarizer film is free from at least one of an inorganic acid zinc salt, a zinc halogenide salt and an organic acid zinc salt without any photocurable functional group.
12. The polarizing plate according to claim 1 , wherein the polarizer film is free from at least one of an inorganic acid anion, a halogenated anion and an organic acid anion without any photocuring functional group.
13. The polarizing plate according to claim 1 , further comprising: a protective layer stacked on at least one side of the polarizer film.
14. An optical display device comprising the polarizing plate according to claim 1 .