Optical plastic film, and optical laminate, polarization plate, and image display device using same

Abstract

The present disclosure addresses the problem of providing an optical plastic film such that rainbow unevenness when viewed with naked eyes and blackout when viewed with polarized sunglasses can be suppressed without any axis alignment or increase in the in-plane phase difference. Disclosed is an optical plastic film satisfying the following conditions 1 and 2: <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; and <Condition 2> when the 30 small samples are processed in the same manner as in condition 1 and an angle of slow axis of each subdivided region of each small sample is measured, a percentage of small samples in which a standard deviation a calculated from the angle of slow axis of each region measured is 0.8 degrees or more, among the 30 small samples is 50% or more.