Patent ID: 8211514

Claim:
A reverse dispersion retardation film, formed by stretching a film comprising a norbornene-based ring-opening copolymer containing a structural unit (A) represented by the following general formula (1): wherein in the formula (1), m represents an integer of any one of 0 and 1, R 1 represents any one of atoms and groups selected from the group consisting of: a hydrogen atom; halogen atoms; substituted or unsubstituted hydrocarbon groups, each of which may include at least one linking group selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, and a silicon atom, and which has 1 to 30 carbon atoms; and polar groups, X 1 represents any one of groups selected from the group consisting of a group represented by a formula: —CH═CH— and a group represented by a formula: —CH 2 CH 2 —, a and b each independently represent an integer of 0 to 6, Y, which may be the same or different when provided in plurality in the single structural unit, represents at least one group selected from the group consisting of a methylene group, a carbonyl group, an oxy group, and alkylimino groups having 1 to 5 carbon atoms, and Z, which may be the same or different when provided in plurality in the single structural unit, represents at least one group selected from the group consisting of a methylene group, a carbonyl group, an oxy group, and alkylimino groups having 1 to 5 carbon atoms and a structural unit (B) represented by the following general formula (2): wherein in the formula (2), n represents an integer of any one of 0 and 1, X 2 represents any one of groups selected from the group consisting of a group represented by a formula: —CH═CH— and a group represented by a formula: —CH 2 CH 2 —, R 2 , R 3 , R 4 , and R 5 each independently represent any one of atoms and groups selected from the group consisting of: a hydrogen atom; halogen atoms; substituted or unsubstituted hydrocarbon groups, each of which may include at least one linking group selected from the group consisting of an oxygen atom, a nitrogen atom, a sulfur atom, and a silicon atom, and which has 1 to 30 carbon atoms; and polar groups, wavy lines d and e each represent a configuration of any one of an endo and an exo, and a wavy line f represents a configuration of any one of an endo and an exo, wherein a total amount of the structural unit (A) and an exo-form structural unit, in which the wavy line f represents the exo configuration, among the structural units (B) is not less than 20 mol % but not more than 65 mol % of all the structural units.