Patent ID: 7671193
Filing Date: 2010-03-02
Classification: C08B

Abstract:
1. A process for preparation of cellulose acetate having a degree of acetyl substitution in the range of 2.636 to 2.958 wherein the degree of acetyl substitution at the 2-, 3-, and 6- positions satisfy the following formula (I) which comprises the steps of: reacting cellulose in a solvent with acetic acid and acetic anhydride in the presence of an acid catalyst to synthesize cellulose acetate; and ripening the synthesized cellulose acetate in the presence of the remaining acid catalyst, an acetyl donor, and water or an alcohol at a temperature of 30 to 70° C., and under a condition that the amount of water and the alcohol is in the range of 0.1 to 10 mol % based on the amount of the acetyl donor in the ripening step: in which 2DS is the degree of acetyl substitution at 2-position; 3DS is the degree of acetyl substitution at 3-position; and 6DS is the degree of acetyl substitution at 6-position.