POLARIZING PLATE AND OPTICAL DISPLAY APPARATUS
A polarizing plate and an optical display apparatus are disclosed. A polarizing plate includes a polarizer and a protective layer on at least one surface of the polarizer, and the polarizer includes a polyvinyl alcohol film containing a dichroic substance and contains zinc cations and potassium cations, and the polarizing plate has a value of 0.1 or less, as calculated according to Equation 1.
1 . A polarizing plate comprising a polarizer and a protective layer on at least one surface of the polarizer,
wherein the polarizer comprises a polyvinyl alcohol based film containing a dichroic material and contains zinc cations and potassium cations, and
wherein the polarizing plate has a value of 0.1 or less, as calculated according to the following Equation 1:
Tc
(
400
nm
)
/
Tc
(
730
nm
)
,
where Tc (400 nm) is a cross transmittance of the polarizing plate at a wavelength of 400 nm (unit: %), and Tc (730 nm) is a cross transmittance of the polarizing plate at a wavelength of 730 nm (unit: %).
2 . The polarizing plate as claimed in claim 1 , wherein Tc (400 nm) is 0.010% or less and Tc (730 nm) is from 0.05% to 0.20%.
3 . An optical display apparatus comprising the polarizing plate as claimed in claim 2 .
4 . The polarizing plate as claimed in claim 1 , wherein the zinc cations are present in an amount of 0.15 wt % or more, and the potassium cations are present in an amount of 0.55 wt % in the polarizer.
5 . An optical display apparatus comprising the polarizing plate as claimed in claim 4 .
6 . The polarizing plate as claimed in claim 1 , wherein the polarizer contains the zinc cations and the potassium cations in a total amount of 0.60 wt % or more.
7 . An optical display apparatus comprising the polarizing plate as claimed in claim 6 .
8 . The polarizing plate as claimed in claim 1 , wherein the polarizer contains the zinc cations and the potassium cations in a weight ratio (zinc cations:potassium cations) of 1:2.5 or more.
9 . An optical display apparatus comprising the polarizing plate as claimed in claim 8 .
10 . The polarizing plate as claimed in claim 1 , wherein the polyvinyl alcohol based film comprises a derivative of polyvinyl alcohol containing a hydrophilic functional group and a hydrophobic functional group.
11 . An optical display apparatus comprising the polarizing plate as claimed in claim 10 .
12 . The polarizing plate as claimed in claim 1 , wherein the polarizing plate has a single transmittance change rate of 3% or less, as calculated according to the following Equation 2:
s
ingle
transmittance
change
rate
=
[
|
Ts
2
-
Ts
1
❘
"\[RightBracketingBar]"
/
Ts
1
]
×
100
,
where Ts1 is an initial single transmittance of the polarizing plate (unit: %), and Ts2 is a single transmittance of the polarizing plate after the polarizing plate is left at 105° C. for 1,500 hours (unit: %).
13 . An optical display apparatus comprising the polarizing plate as claimed in claim 12 .
14 . An optical display apparatus comprising the polarizing plate as claimed in claim 1 .