Patent ID: 8158039

Claim:
A method of preparing an optical film comprising steps of preparing a mixture of components, preparing a film by melt-cast method, and drying the film, wherein the component comprises; a cellulose ester, a sugar ester compound formed by esterification of a sugar compound composed of 1 to 12 structures selected from a furanose structure and a pyranose structure, an acryl resin, and an anti-oxidant, wherein an amount of the sugar ester compound is 0.5 to 35% by weight of the cellulose ester, and the anti-oxidant is a compound having partial structure represented by one of Formulas C-1, C-2, C-3, C-4 and C-5 in a molecule, wherein, Ph 1 and Ph′ 1 are independently a phenylene group which may be substituted by a phenyl group, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, an alkylcycloalkyl group having 6 to 12 or an aralkyl group having 7 to 12 carbon atom, and X is a single bond, a sulfur atom or a —CHR 6 — group, R 6 is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms, wherein, Ph 2 and Ph′ 2 are independently a phenyl group or a biphenyl group each of which may be substituted by an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8, an alkylcycloalkyl group having 6 to 12 carbon atoms or an aralkyl having 7 to 12 carbon atoms, wherein Ph 3 is a phenyl group or a biphenyl group each of which may be substituted by an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8, an alkylcycloalkyl group having 6 to 12 carbon atoms or an aralkyl having 7 to 12 carbon atoms, wherein Ph 4 is an alkyl group having 1 to 20 carbon atoms or a phenyl group each of which may be substituted by an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8, an alkylcycloalkyl group having 6 to 12 carbon atoms or an aralkyl having 7 to 12 carbon atoms, and wherein Ph 5 , Ph′ 5 and Ph″ 5 are each an alkyl group having 1 to 20 carbon atoms or a phenyl group each of which may be substituted by an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8, an alkylcycloalkyl group having 6 to 12 carbon atoms or an aralkyl having 7 to 12 carbon atoms.