Patent ID: 9383479
Filing Date: 2016-07-05
CPC Classification: G02B,Y10T

Claim Text:
1. A method for producing an optical film comprising a first domain of a cellulose acylate polymer composition and a second domain disposed inside the first domain, wherein the second domain is a bubble having a morphology anisotropy, and the mean alignment direction of the main chain of the polymer molecule in the first domain differs from the mean direction of the major axis of the second domain, the method comprising: stretching a film comprising a cellulose acylate polymer composition and having a haze of at most 1% at a stretching temperature of from (Tg−20)° C. to Tc° C. and at a draw ratio of from 30 to 150% wherein Tg means the glass transition temperature (unit, ° C.) of the film and Tc means the crystallization temperature (unit, ° C) of the film, wherein a stretching maximum stress to the film in a stretching direction during the stretching is controlled to be from 10 MPa to 60 MPa.