Process for producing cellulose ester film

摘要

A cellulose ester film that excels in uniformity of retardation as an optical property, especially uniformity of retardation in the direction of film width, and further contrast; a process for producing such a cellulose ester film; and making use of the film, an optical film, polarizing plate and liquid crystal display unit. There is provided a process characterized by subjecting, to melting film formation, a solid cellulose ester having been suspension washed with a poor organic solvent to cellulose ester in the presence of an antioxidant so that the content of free acids in the cellulose ester is 50 ppm or less.