| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a cellulose ester film high in transparency, improved in optical defects and high in mechanical strength, enabling a highly concentrated solution of the cellulose ester to be prepared even if a non-chlorine-based solvent is used, without the need of any special dissolving equipment such as in the case of cooling dissolution method. SOLUTION: This method for producing a cellulose ester film comprises casting on a substrate a solution prepared by dissolving in a non-chlorine-based organic solvent a cellulose ester made by acrylating cellulose with acetyl groups and 3-4C acyl groups, followed by evaporating the solvent to form the aimed film; wherein the cellulose ester contains <=100 ppm of alkaline earth metal and meeting the following relationships: (I) 2.6<=A+B<=3.0; (II) 1.4<=A<=2.5; and (III) 0.5<=B<=1.2. In the above, A is acetyl group substitution degree, and B is 3-4C acyl group substitution degree.
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