Daicel Chemical Industries, Ltd.

Hirofumi Sasai

Toru Ozaki

Hiroki Taniguchi

Michiyo Nakai

Shinsuke Suzuki

Hiroshi Ogawa

Cellulose acetates and process for producing the cellulose acetates

The present invention provides a cellulose triacetate which exhibits a satisfactory filtration performance Thus, the present invention provides a cellulose triacetate whose occlusion constant (K) determined by the following method is 70 or less. Method: the cellulose triacetate is dissolved in a solvent mixture of methylene chloride/methanol (9/1 w/w) to form a 16% by weight (as a solid concentration) solution, which is then filtered under a constant pressure at the filtration pressure of 3 kg/cm and the temperature of 25&deg; C. using a muslin filter to determine a filtered volume with the lapse of time, from which the slope of a linear curve represented by t/V&minus;t (wherein t is a filtration time (sec) and V is a filtered volume (ml)) is calculated to obtain an occlusion constant (K) where K&equals;slope&times;2&times;10 .

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Hyogo, Japan

Hirofumi Sasai