US 12,321,000 B2
Film stacks for thin circular polarizers
Alex P. Pongratz, Minneapolis, MN (US); David T. Yust, Woodbury, MN (US); and Michael A. Johnson, Stillwater, MN (US)
Assigned to 3M INNOVATIVE PROPERTIES COMPANY, St. Paul, MN (US)
Appl. No. 17/757,755
Filed by 3M INNOVATIVE PROPERTIES COMPANY, St. Paul, MN (US)
PCT Filed Dec. 22, 2020, PCT No. PCT/IB2020/062336
§ 371(c)(1), (2) Date Jun. 20, 2022,
PCT Pub. No. WO2021/130672, PCT Pub. Date Jul. 1, 2021.
Claims priority of provisional application 62/953,642, filed on Dec. 26, 2019.
Prior Publication US 2023/0034724 A1, Feb. 2, 2023
Int. Cl. G02B 5/30 (2006.01); B32B 27/36 (2006.01); B32B 27/40 (2006.01); G02B 1/04 (2006.01); G02B 1/08 (2006.01)
CPC G02B 5/305 (2013.01) [B32B 27/36 (2013.01); B32B 27/40 (2013.01); G02B 1/04 (2013.01); G02B 1/08 (2013.01); G02B 5/3033 (2013.01); G02B 5/3041 (2013.01); G02B 5/3083 (2013.01); B32B 2307/40 (2013.01); B32B 2551/00 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A film stack comprising:
(a) a quarter-wave retarder comprising a layer of linear photopolymerized polymer or liquid crystal polymer,
(b) a transparent aliphatic cross-linked polyurethane layer having a glass transition temperature in a range from 11 to 27° C. and a Tan Delta peak value in a range from 0.5 to 2.5, and
(c) an oriented layer comprising polyvinyl alcohol, the polyurethane layer disposed between, and directly bonding together, the quarter-wave retarder and the layer comprising polyvinyl alcohol, the layer of linear photopolymerized polymer or liquid crystal polymer being disposed directly on the polyurethane layer.