| abstract |
An optically isotropic film of an aromatic polyethersulfone, which is useful as a substrate for a liquid crystal display device, and an optically anisotropic, uniaxially oriented film of an aromatic polyethersulfone, which is useful as a phase difference plate for a liquid crystal display device. The optically isotropic film is produced by casting an aromatic polyethersulfone solution composition comprising 15 to 40 parts by weight of a solvent which contains at least 60% by weight of 1,3-dioxolane and can dissolve an aromatic polyethersulfone and 10 parts by weight of the aromatic polyethersulfone, on a substrate, and heating the cast solution composition containing a solvent to evaporate the solvent off. |