US 11,814,491 B2
Transparent film, optical material comprising the same, and display device comprising the same
Min Sang Park, Daejeon (KR); Jin Hyung Park, Daejeon (KR); Seung Min Jeon, Daejeon (KR); and Yoo Seock Hwang, Daejeon (KR)
Assigned to SK Innovation Co., Ltd., Seoul (KR); and SK ie technology Co., Ltd., Seoul (KR)
Filed by SK Innovation Co., Ltd., Seoul (KR); and SK IE Technology Co., Ltd., Seoul (KR)
Filed on Aug. 5, 2020, as Appl. No. 16/985,562.
Claims priority of application No. 10-2019-0097130 (KR), filed on Aug. 9, 2019.
Prior Publication US 2021/0040282 A1, Feb. 11, 2021
Int. Cl. C08J 5/18 (2006.01); C08G 73/10 (2006.01)
CPC C08J 5/18 (2013.01) [C08G 73/10 (2013.01); C08J 2379/08 (2013.01)] 8 Claims
 
1. A transparent polyimide-based film in which light which is generated when one polarized light is transmitted through the film and in which two waves are mixed with each other satisfies the following Relational Expressions 1 and 2:
0.90 A≤T≤1.10 A  [Relational Expression 1]
θ≤30  [Relational Expression 2]
wherein T is the sum of magnitudes of amplitudes when the two waves of the transmitted light interfere with each other, A is a wave's amplitude of the polarized light, and θ is a retardance angle (°) of a wave traveling to a slow axis of the transparent film, of the two waves, and
wherein the transparent film is manufactured using a drying process after solution casting, the drying process comprises two or more drying steps, and the drying conditions in at least two of the drying steps is different.