Resin composition, optical compensation film using the same and production method of optical compensation film

A resin composition, comprising:

• from 70 to 99.99 wt % of a resin component;
• and
• from 0.01 to 30 wt % of an additive comprising an aromatic hydrocarbon ring or aromatic heterocyclic ring,
• wherein the resin component consists of:
• from 10 to 99 wt % of a cellulose-based resin of formula (1);
• and
• from 90 to 1 wt % of a fumaric acid diester polymer comprising 60 mol % or more of a fumaric diester residue unit of formula (2):
• wherein R1, R2 and R3 are each independently hydrogen or an acyl group having a carbon number of from 1 to 12;
• and
• wherein R4 and R5 are each independently an alkyl group having a carbon number of from 1 to 12.