| 摘要 |
PROBLEM TO BE SOLVED: To provide a protective film for a polarizing plate, which is excellent in durability at a high temperature and a high humidity even if it is a thin film. SOLUTION: The protective film for the polarizing plate is a film of a cellulose ester in which the substitution degree of acetyl group is 2.50-2.78. The protective film for the polarizing plate is characterized in that when the dimension of a film, allowed to stand for 12 h in an ordinary temperature ordinary humidity atmosphere of 23±3°C and 55±3% RH, in the casting direction is defined as Lmd (mm) and the dimension of the film in the width direction is defined as Ltd (mm), and when the dimension of a film, allowed to stand for 50 h in a high temperature high humidity atmosphere of 80±3°C and 90±3% RH and further allowed to stand for 12 h in the ordinary temperature ordinary humidity atmosphere, in the casting direction is defined as Hmd (mm) and the dimension of the film in the width direction is defined as Htd (mm), both of expansion-contraction rates Smd and Std are each within the range of±0.3%. COPYRIGHT: (C)2008,JPO&INPIT |
