RETARDATION FILM

摘要

A retardation film containing a norbornene copolymer. It is excellent in heat resistance and significantly reduced in specific gravity, birefringence, photoelasticity, and wavelength dispersion. It further has the high ability to compensate for retardation. The retardation film comprises a norbornene copolymer composition containing a norbornene copolymer comprising 40-60 mol% repeating units derived from at least one norbornene monomer selected from the group consisting of a monomer represented by the general formula (I), a monomer represented by the general formula (II), a monomer represented by the general formula (III), a monomer represented by the general formula (IV), and a monomer represented by the general formula (V) and 60-40 mol% repeating units derived from an acyclic olefin monomer. When the norbornene copolymer composition is formed into a film and then stretched in a stretch ratio of 2 while being heated at the glass transition temperature determined from dynamic viscoelasticity, then the stretched film has an in-plane birefringence ?n defined by the following equation of 0.0033 or larger. ?n = |nx-ny|