| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject ester film reduced in content of an Fe component and useful for a protective film for a liquid crystal polarizing plate by using a triacetylcellulose film improved by reducing foreign materials of luminescent spots. SOLUTION: This ester film is obtained by reducing foreign materials of luminescent spots so as to provide <=1 ppm amount of a contained Fe component, <=60 ppm amount of a contained Ca component and 15-70 ppm amount of a contained Mg component. Triacetylcellulose is preferred as the cellulose ester. The number of luminescent spots having >=0.01 mm particle diameter is preferably <=10 spots/cm2, 3.4-4.5 (weight-average molecular weight)/(number- average molecular weight) in the case of cotton linter and 3.5-5.0 (weight-average molecular weight)/(number-average molecular weight) in the case of wood pulp and the cellulose ester has preferably 250-300 degree of polymerization in the case of the cotton linter and 230-280 degree of polymerization in the case of the wood pulp and 100-250 cP viscosity at %.
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