Patent ID: 8465673

Claim:
A retardation film comprising a polymer film wherein the polymer film comprises a polymer having a hydroxyl group and a humidity dependence improver for polymer film, comprising a compound of the following formula (6), (6b) or (9): wherein Ra 3 represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group; wherein Ra 4 represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and Rd 1 and Rd 2 each independently represent an alkyl group or an aryl group; and wherein Rb 3 and Rc 3 each independently represent an alkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group.