PRODUCTION OF CELLULOSE TRIACETATE FILM

摘要

PURPOSE:To improve the tear strength and bending resistance of film by a method wherein the film is dried in such a condition as to give a specific relationship between a volatile portion of the film and the film surface temperature. CONSTITUTION:The subject production method comprises a casting process of stretching on a supporting body having its surface temperature maintained at not higher than 10 deg.C a dope wherein the concentration based on the sum of the weights of cellulose triacetate and other component to be hardened after drying is 18-35wt.% and the ratio of the solvents other than methylene chloride in the solvent composition is 13-25wt.% and a drying process of removing the cast film from the supporting body and drying the same. Given that a volatile portion of the film is X (%) and the film surface temperature is Y ( deg.C), the film is dried in a condition within a range of the expressions indicating relation- ship between X and Y. This film production method permits the crystallization of cellulose triacetate to be controlled in the drying process and improves tear strength and bending resistance of the film.