METHOD OF REMOVING GROUPS OF HEXENURONIC ACIDS FROM CELLULOSE BY HEAT TREATMENT Russian patent published in 1999 - IPC

FIELD: treatment of cellulose, in particular, cellulose of hard wood by removal of lignin in the course of cooking and, if required, further removal of lignin with the aid of oxygen to attain Kappa number below 24. SUBSTANCE: cellulose containing no lignin is heated and treated at temperature from about 85 to 105 C, preferably, from 90 to 110 C with pH about 2 to 5 to reduce Kappa number by 2-9 units by removal from cellulose of at least 50% of groups of hexenuronic acids. Treated cellulose is bleached with the help of at least one-stage process. As a result of selective removal of groups of hexenuronic acids from cellulose, consumption of bleaching agent is considerably reduced. EFFECT: higher efficiency. 19 cl, 2 dwg, 2 tbl