US 12,169,298 B2
Polarizing plate and image display device comprising the same
Jung Hyun Seo, Daejeon (KR); Kyungki Hong, Daejeon (KR); Yeongrae Chang, Daejeon (KR); and Jin Young Park, Daejeon (KR)
Assigned to LG CHEM, LTD., Seoul (KR)
Appl. No. 16/760,528
Filed by LG CHEM, LTD., Seoul (KR)
PCT Filed Mar. 6, 2019, PCT No. PCT/KR2019/002606
§ 371(c)(1), (2) Date Apr. 30, 2020,
PCT Pub. No. WO2019/172651, PCT Pub. Date Dec. 9, 2019.
Claims priority of application No. 10-2018-0026390 (KR), filed on Mar. 6, 2018; and application No. 10-2019-0025662 (KR), filed on Mar. 6, 2019.
Prior Publication US 2021/0223453 A1, Jul. 22, 2021
Int. Cl. G02B 5/30 (2006.01); G02B 1/14 (2015.01); G02F 1/1335 (2006.01); G02F 1/13363 (2006.01)
CPC G02B 5/3083 (2013.01) [G02B 1/14 (2015.01); G02B 5/305 (2013.01); G02F 1/133531 (2021.01); G02F 1/133638 (2021.01); C09K 2323/035 (2020.08)] 13 Claims
 
1. A polarizing plate comprising:
a polarizer;
a first hard coating layer positioned on the polarizer, and containing a first binder resin comprising a (meth) acrylate-based (co) polymer;
a light transmitting substrate positioned on the side of the first hard coating layer opposite to the polarizer, and having a retardation of at least 3000 nm and in-plane birefringence; and
a second hard coating layer positioned on the side of the light transmitting substrate opposite to the first hard coating layer, and comprising a second binder resin and solid inorganic nanoparticles dispersed in the binder resin,
wherein an acute angle formed by a slow axis of the light transmitting substrate and an absorption axis of the polarizer is 5 to 85°,
wherein a thickness of the second hard coating layer is 45 μm or less,
wherein a thickness ratio of the first hard coating layer and the second hard coating layer is 1:0.5 to 1:0.63, and
wherein a rainbow change rate (ΔRb) of the polarizing plate calculated by Mathematical Formula 1 is 2.5% or less:
ΔRb=(maximum reflectance at 450to 650 nm−minimum reflectance at 450to 650 nm)÷(mean reflectance at 450to 650 nm)×100,  [Mathematical Formula 1]
wherein a reflectance of the polarizing plate is measured under conditions of a 5º reflection mode, 2 nm slit width, and an analysis wavelength range of 380 to 780 nm, using a UV-Vis spectrometer, from which reflectance data at 450 to 650 nm are derived, and then a mean reflectance and difference between a maximum reflectance and a minimum reflectance at 450 to 650 nm are calculated and substituted in the Mathematical Formula 1.