| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide cellulose triacetate capable of suppressing generation of fine foreign matters difficult to be filtrated, and easily removing the foreign matters by filtration and to provide a method for producing thereof. Ž<P>SOLUTION: There is provided a cellulose triacetate produced by a production method including an oxidation step and a saponification and maturation step, and having a blocking constant (K) measured by the following method of not more than 70, an average acetylation degree of 59-62.5%, and a viscosity average polymerization degree of 200-400. In the measuring method, the cellulose triacetate is dissolved in a mixture solvent having a rate of methylene chloride/methanol of 9/1 (weight ratio) to obtain a solution of 16 wt.% (solid concentration). The solution is filtrated through a cannequin filter medium under constant pressure at a pressure of 3 kg/cm<SP>2</SP>at 25°C, and the gradient of a line represented by t/V vs t [t is the filtration time (s) and V is the filtration rate (ml)] is calculated from the filtration rate measured over time, so as to obtain the blocking constant (K) from the formula K=gradient×2×10<SP>4</SP>. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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