HIGH WAVELENGTH DISPERSION OPTICAL RETARDATION PLATE

摘要

PROBLEM TO BE SOLVED: To provide an optical retardation plate with large wavelength dispersion characteristics of birefringence and being obtainable as a whole cloth film with excellent solubility in a solvent and with high homogeneity by means of a solvent cast method. SOLUTION: The optical retardation plate composed of a copolymer obtained by polymerizing an acyclic olefin monomer (A) selected from ethylene and a 3-20C α-olefin compounds, a cyclic olefin monomer (B) selected from cyclic olefin compounds such as norbornene and an aromatic vinyl monomer (C) selected from vinyl compounds with an aromatic hydrocarbon unit such as styrene with a copolymerization ratio of 5-40 mol% aromatic vinyl monomer (C) and 60-95 mol% sum total of the acyclic olefin monomer (A) and the cyclic olefin monomer (B) and having >=1.1 wavelength dispersion coefficient α=R450 /R590 expressed by the ratio of retardation at 450 nm wavelength R450 to retardation at 590 nm wavelength R590 is provided.