US 12,292,373 B2
Optical plastic film, and optical laminate, polarization plate, and image display device using same
Yoshiko Tanaka, Tokorozawa (JP); Shosei Kubota, Kashiwa (JP); Takashi Kuroda, Moriya (JP); and Akinobu Ushiyama, Moriya (JP)
Assigned to DAI NIPPON PRINTING CO., LTD., Tokyo (JP)
Filed by DAI NIPPON PRINTING CO., LTD., Tokyo (JP)
Filed on Dec. 12, 2023, as Appl. No. 18/537,293.
Application 18/537,293 is a continuation of application No. 17/907,433, granted, now 11,885,734, previously published as PCT/JP2021/013463, filed on Mar. 30, 2021.
Claims priority of application No. 2020-065374 (JP), filed on Mar. 31, 2020.
Prior Publication US 2024/0110860 A1, Apr. 4, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. G01N 17/00 (2006.01); G02F 1/1335 (2006.01)
CPC G01N 17/00 (2013.01) [G02F 1/133528 (2013.01); G02F 2201/50 (2013.01)] 6 Claims
OG exemplary drawing
 
1. An optical plastic film satisfying the following condition 1:
<Condition 1>
when a large sample with a size of 200 mm×300 mm is cut out from a plastic film, the large sample is divided into 30 small samples of 40 mm×50 mm, a region of 30 mm×40 mm obtained by excluding 5 mm from each edge of each small sample is subdivided into 47,000 or more regions, and an in-plane phase difference of each subdivided region is then measured, a percentage of small samples in which an average of the in-plane phase difference of each region measured is 50 nm or more and 1,200 nm or less, among the 30 small samples is 50% or more.