Polarizer, method for preparing the same, and polarizing plate provided with the same
A polarizer includes a polyvinyl alcohol-based resin film in which iodine is oriented by adsorption, wherein an iodine orientation ratio, represented by the following Equation I, is about 20% to about 30%, Iodine orientation ratio = R I R PVA , ( I ) R I being an average in-plane retardation value of iodine in infrared regions of 845.1 nm, 903.3 nm, 952.1 nm, 1000.0 nm, 1046.5 nm, and 1092.7 nm, and R PVA being an average in-plane retardation value of a polyvinyl alcohol-based resin in infrared regions of 845.1 nm, 903.3 nm, 952.1 nm, 1000.0 nm, 1046.5 nm, and 1092.7 nm.
1. A polarizer, comprising:
a polyvinyl alcohol-based resin film in which iodine is oriented by adsorption, wherein an iodine orientation ratio, represented by the following Equation I, is about 0.20 to about 0.30,
Iodine
orientation
ratio
=
R
I
R
PVA
,
(
I
)
R I being an average of in-plane retardation values of iodine in infrared regions of 845.1 nm, 903.3 nm, 952.1 nm, 1000.0 nm, 1046.5 nm, and 1092.7 nm, and R PVA being an average of in-plane retardation values of a polyvinyl alcohol-based resin in infrared regions of 845.1 nm, 903.3 nm, 952.1 nm, 1000.0 nm, 1046.5 nm, and 1092.7 nm.
2. The polarizer according to claim 1 , wherein said polarizer has a boric acid content of about 10% to about 20%.
3. The polarizer according to claim 2 , wherein said polarizer has a display uniformity of about 0.03 cd to about 0.1 cd.
4. A method for preparing a polarizer, the method comprising:
dyeing a polyvinyl alcohol-based resin film with an iodine-containing dyeing solution according to claim 1 ;
cross-linking the dyed film in a drawing ratio of about 1.0 to about 1.5; and
drawing the cross-linked film in a drawing bath containing about 1% to about 3% boric acid,
wherein the total drawing ratio is about 5.8 to about 6.5.
5. The method as claimed in claim 4 , wherein said dyeing solution has a temperature of about 20° C. to about 40° C.
6. The method as claimed in claim 4 , wherein said drawing bath has a temperature of about 40° C. to about 62° C.
7. A polarizing plate comprising the polarizer according to claim 1 .
8. The polarizing plate according to claim 7 , wherein said polarizing plate has a structure in which a protective film is provided on at least one surface of the polarizer.
9. The polarizing plate according to claim 8 , wherein said protective film has an in-plane retardation value (R o ), represented by the following Equation II, of about 40 nm to about 60 nm:
Ro =(n x −n y )× d (II),
n x being a film in-plane maximum refractive index, n y being a refractive index in one direction perpendicular to n x , and d being a film thickness (nm).