Patent ID: 7569259

Claim:
A cellulose ester film comprising a plasticizer represented by Formula (2) in an amount of 1 to 25 weight % based on the total weight of the cellulose ester film: wherein R 6 to R 20 each independently represent a hydrogen atom, a cycloalkyl group, an aralkyl group, an alkoxy group, a cycloalkoxy group, an aryloxy group, an aralkyloxy group, an acyl group, a carbonyloxyl group, an oxycarbonyl group or an oxycarbonyloxy group, provided that R 6 to R 20 may have further a substituent; and at least one of R 6 to R 20 , at least one of R 11 to R 15 and at least one of R 16 to R 20 each is not a hydrogen atom; and R 21 represents an alkyl group; wherein the cellulose ester film satisfies the following Relationship (2) and Relationship (3), 2.5 ≦X+Y≦ 2.9 Relationship (2) 0.1≦Y≦2.0 Relationship (3) wherein X is a degree of substitution with acetic acid and Y is a degree of substitution with an aliphatic acid having 3 to 5 carbon atoms.