Patent ID: 7399440

Claim:
A process for making a cellulose ester film having a dry thickness of 20 to 60 μm, the process comprising the steps of: providing a cellulose ester dope; casting the cellulose ester dope on a support to form a cellulose ester web; peeling the cellulose ester web at a peel position from the support; transporting the peeled web to a dryer, drying the peeled web therein to forma cellulose ester film; and winding the cellulose ester film around a spool, wherein the cellulose ester dope is provided by a method comprising the steps of a) mixing a cellulose ester and one or more solvents comprising an organic solvent with a boiling point BP (° C.) as the main organic solvent in a tightly sealed pressure resistant vessel and heating the resulting mixture to around BP, b) unsealing the vessel at that temperature to allow it to stand for not less than 6 minutes, re-sealing the vessel and further heating the mixture to a temperature of from BP to BP+50 (° C.) to obtain a cellulose ester dope.