| abstract |
A main chain type liquid polyester, characterized in that it comprises at least two units of an aromatic diol unit, an aromatic dicarboxylic acid unit and an aromatic hydroxycarboxylic acid unit as essential units and, at at least one terminal thereof, has a structural unit containing a cationically polymerizable group. The main chain type liquid polyester, when used as an optical material, is excellent in the orientation retaining capability which means the capability of retaining a structure of a liquid crystal having been oriented and then fixed under practical service conditions, and also exhibits excellent mechanical strength. |