PURPOSE: To improve the wavelength dispersive characteristic, resistance to heat and wet heat, etc., by specifying the material for the phase-difference film.
CONSTITUTION: This phase-difference film consists of an aromatic polysulfone resin with the repeating unit expressed by -(Ph-X1-Ph-X2- to Ph-X1)n. In the formula X1-X1 is a bond linking aromatic rings or a direct bond, at least one is an SO2 group, Ph is an aromatic ring, at least one SO2 group is present in the repeating unit, and an aliphatic group, a bond such as O, S, CO, COO and CONH or an aromatic direct bond are exemplified as the bond linking atomatic rings in addition to the SO2 group. A direct bond of SO2, O and aromatic rings are preferably used for this phase-difference film.
MIYAZAKI KAZUO
SUZUKI YOSHITAKE
