Optical retardation film

An anisotropic polymer layer exhibiting a tilted structure with an optical axis having a tilt angle θ relative to the plane of the layer, obtained by polymerizing a polymerizable mesogenic material comprising at least one compound of the formula:

• P-(Sp-x)n-MG-R I
• wherein
• p is a polymerizable group,
• Sp is a spacer group having 1 to 20 C atoms,
• X is a group of —O—, —S—, —CO—, —COO—, —OCO—, —OCOO— or a single bond,
• n is 0 or 1,
• MG is a mesogenic or mesogenicity supporting group:
• and
• R is an alkyl radical with up to 25 C atoms optionally unsubstituted, mono- or polysubstituted by halogen or CN, optionally one or more non-adjacent CH2 groups are replaced, independently, by —O—, —S—, —NH—, —N(CH3)—, —CO—, —COO—, —OCO—, —OCO—O—, —S—CO—, —CO—S— or —C≡C— where oxygen atoms are not linked directly to one another, or R is halogen, cyano or, independently, P-(Sp-X)n— as defined in formula I;
• wherein the polymerizable mesogenic material is a mixture of:
• a1) 10 to 99% by weight of at least one mesogen according to formula I having one polymerizable functional group,
• a2) 0 to 70% by weight of at least one mesogen according to formula I having two or more polymerizable functional groups, and
• b) 0.01 to 5% by weight of an initiator.