CYCLIC OLEFIN RING-OPENING COPOLYMER, USE THEREOF, AND PROCESS FOR PRODUCTION OF RETARDER COMPRISING THE COPOLYMER

摘要

A cyclic olefin ring-opening copolymer comprising a constituent unit which is derived from a cyclic olefin having a polar group and a hydrocarbon group, a constituent unit which is derived from tricyclo[4.3.0.1<SUP>2,5</SUP>]deca-3-ene which may have a substituent or the like and a constituent unit which is derived from a cyclic olefin having no polar group. There are provided: a cyclic olefin copolymer which is excellent in heat resistance and optical properties, can be suitably formed into a film or sheet, and can be stretched even at a relatively low temperature around Tg without causing disadvantages such as whitish turbidity; a film or sheet comprising the cyclic olefin copolymer which is excellent in optical properties and heat resistance and is suitable for stretching at a relatively low temperature; a retarder which is excellent in optical properties and heat resistance, shows a steady phase difference, and shows no fluctuation of an optical axis; and a process for producing the retarder.