HYDROXYPROPYLCELLULOSE PRODUCTION PROCESS Russian patent published in 2003 - IPC

FIELD: cellulose derivatives. SUBSTANCE: cellulose is treated with 7-9% aqueous sodium hydroxide solution, resulting alkaline cellulose is ground and blown through with nitrogen. Hydroxypropylation is performed in inert gas flow at linear velocity 0.01-0.5 m/s, while propylene oxide is continuously fed in amounts 1.5-2.4 wt parts per 1 wt part cellulose during 1 to 4 h. Neutralization is performed by treating product with aqueous solution of either acid alkali metal salt (with corresponding acid) in concentration 5-15%, or mixed acid plus neutral alkali metal salts in concentration 5-15%, or neutral alkali metal salt in concentration 5-15% at 60-90 C. In this stage, unreacted propylene oxide is distilled off. Invention can be applied in chemical, food, pharmaceutical, and other industries. EFFECT: increased technological appropriateness, reduced number of operations and amount of by-products, and improved process safety. 2 cl, 1 tbl, 8 ex