| 摘要 |
PROBLEM TO BE SOLVED: To obtain a cellulose ester optical film that has sufficient optical properties and mechanical properties as an optical film and is formed by a melt casting method having a high effective utilization ratio of resources. SOLUTION: The method for producing a cellulose ester optical film comprises heating, melting and extruding a mixture of an unheated cellulose ester A, a heated, melted and recovered cellulose ester B and at least one kind of an additive. The variation ratio of a yellow index (Y1) value represented by formula (1) variation ratio of a yellow index (Y1) value=(YI<SB>1</SB>-YI<SB>2</SB>)/YL<SB>1</SB>(YI<SB>1</SB>is the YI value of a film using only the cellulose ester A; YI<SB>2</SB>is the YI value using the unheated cellulose ester A and the recovered cellulose ester B) is≥-0.5 and≤0.0. COPYRIGHT: (C)2007,JPO&INPIT |
