Patent ID: 8445079

Claim:
A retardation film comprising: a polymer having a repeating unit represented by the following general formula (I): wherein A, A′, B, and B′ each denote a substituent, a and a′ denote the number of substituents of the corresponding A and A′ (an integer of 0 to 3), and b and b′ denote the number of substituents of the corresponding B and B′ (an integer of 0 to 3); A, A′, B and B′ each independently denote a halogen or an alkyl group having 1 to 4 carbon atoms; R 1 and R 2 each independently denote an atom or a group selected from the group consisting of hydrogen, a halogen, an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group, a substituted or unsubstituted vinyl group, a substituted or unsubstituted ethynyl group, an SiR 3 R 4 R 5 group (R 3 to R 5 each independently denote an alkyl group having 1 to 6 carbon atoms or an aryl group) and a CR 6 R 7 (OH) group (R 6 and R 7 each independently denote an alkyl group having 1 to 4 carbon atoms); and X denotes —CR 8 2 — (R 8 denotes hydrogen, an alkyl group having 1 to 4 carbon atoms, a perfluoro group, or a substituted or unsubstituted aryl group), —SiR 9 2 — (R 9 denotes hydrogen, an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group), —O—, —NR 10 — (R 10 denotes hydrogen, an alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted aryl group), —CO—, or —SO 2 —.