Patent ID: 7981994
Filing Date: 2011-07-19
Classification: B29C,B29K,B29L,C08J,G02B

Abstract:
1. A method for producing a cellulose acylate resin film comprising the steps of: film-forming an unstretched cellulose acylate resin film; longitudinally stretching the cellulose acylate film formed in the film-forming step; transversely stretching the cellulose acylate film in the film-forming step; heat-treating the cellulose acylate resin film stretched in the longitudinal stretching step and the transverse stretching step, wherein in the heat treatment step, the cellulose acylate resin film is heat-treated at a temperature of Tg−30° C. to Tg+20° C., Tg representing the glass transition temperature of the cellulose acylate resin, for 10 seconds to 600 seconds while conveying the cellulose acylate resin film at a tension of 2 N/cm the cellulose acylate resin film has a dimensional change under wet heating (6L(w)) and a dimensional change under dry heating (8L(d)) of 0% to 0.3% each, and in the cellulose acylate resin, the acylate group satisfies the following substitution degree: wherein X denotes a substitution degree of an acetyl group; and Y denotes a total substitution degree of a propionyl group, a butyryl group, a pentanoyl group and a hexanoyl group.