| 摘要 |
A process for producing cellulose diacetate is disclosed which comprises the steps of: (a) pretreating and activating 100 parts by weight of cellulose, adding a mixture of 200 to 400 parts of acetic anhydride, 0 to 350 parts of glacial acetic acid, and 0.5 to 5 parts of acid catalyst, heating the reactants to a temperature from 50 DEG C. to 85 DEG C. at approximately a constant rate, maintaining this temperature for 3 to 20 minutes, thereby acetylating cellulose to form primary cellulose acetate; (b) neutralizing the acid catalyst in the reaction mixture containing primary cellulose acetate obtained in step (a), introducing steam under pressure into the system to change the temperature of the system to 125 DEG C. to 170 DEG C., and maintaining this temperature for 30 minutes to 6 hours, thereby hydrolyzing the primary cellulose acetate to accomplish ripening; and (c) flashing the ripened reaction mixture at a temperature of 125 DEG C. to 170 DEG C. by discharging same to the ambient atmosphere, recovering by condensation the gas generated during flashing having an acetic acid/water weight ratio of 70-80/30-20, and simultaneously cooling the remaining liquid reaction mixture to about 100 DEG C., thereby substantially stopping the hydrolysis reaction.
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