| 摘要 |
The object of this invention is to provide an optical film formed of a copolycarbonate having a desired chromatic dispersion and low photoelasticity and having excellent melt processability. The optical film comprises a copolycarbonate composed of 25 to 90 mol% of unit (A) of the following formula,
wherein each of R 1 and R 2 is independently a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms or a halogen atom, each of R 3 and R 4 is independently a hydrocarbon group having 1 to 10 carbon atoms, each of m and n is independently an integer of 0 to 4, and each of p and q is independently an integer of 0 or more, and 10 to 75 mol % of unit (B) of the following formula,
wherein R a is a monocyclic or polycyclic alicyclic hydrocarbon group having 4 to 20 carbon atoms, the alicyclic hydrocarbon group may contain a hetero atom or may have a bridge structure, and q is 0 or 1,
the optical film satisfying the following expression (1), R 450 < R 550 < R 650
wherein R(450), R(550) and R(650) are in-plane retardation values of the film at wavelengths of 450 nm, 550 nm and 650 nm. |
