PURPOSE: To advantageously prepare high-quality hydroxypropyl cellulose industrially, by reacting propylene oxide with an alkali celluloe of low alkali/cellulose ratio and low water/cellulose ratio.
CONSTITUTION: A cellulose, treated with a 10W60wt% aqueous solution of sodium hydroxide, is washed with an aqueous solution containing less than 10wt% of soldium hydroxide, and then dried, to obtain an alkali cellulose of akali/cellulose ratio 0.05W0.16 and water/cellulose ratio 0.2W0.5. After the obtained alkali cellulose is reacted with propylene oxide, with an increase of MS of the product to 1W 2.5, 0.2W0.7pts.wt., based on the weight of cellulose in the product, of water, is added to the reaction system, and then the product is futher reacted with propylene oxide, to increase MS of the reaction product to 2.5 or higher.
SASAGAWA YUKIO
ITOU AKINORI
MARUYAMA HIROMI
SAKAI YOSHITERU
