Retardation film and process for producing the same

A process for producing a retardation film irradiating a mixture of a photosensitive polymer and a low molecular weight compound with light, wherein the ratio z of solubility parameters calculated from the evaporation energy and molecular volume of these photosensitive polymer and low molecular weight compound is larger than 0.93 and smaller than 1.06, wherein the photosensitive polymer is a photosensitive homopolymer or copolymer which has at least one structure represented by the following molecular structures 1 to 9, a main chain represented by the molecular structure 10 is a hydrocarbon, acrylate, methacrylate, maleimide, N-phenylmaleimide or siloxane and the low molecular weight compound has a molecular structure represented by a molecular structure 11 or 12.

• wherein —R1 to —R11=—H, halogen group, —CN, alkyl group or alkyloxy group such as methoxy group or group obtained by fluorinating each of these groups, —R12=alkyl group, e.g., methyl group or ethyl group or group obtained by fluorinating each of these groups, x:y=100 to 0:0 to 100, n=1 to 12, m=1 to 12, j=1 to 12, o=1 to 12, p=1 to 12, q=1 to 12, X, Y=none, —COO, —OCO—, —N═N—, —C═C— or —C6H4—, W1, W2, W3, W4, W5, W6=structure represented by molecular structure 1, 2, 3, 4, 5, 6, 7, 8 or 9.