Process for making carboxymethylcellulose giving solutions having nonthixotropic characteristics

Claim 1

A PROCESS FOR THE MANUFACTURE OF ALKALI METAL SALTS OF CARBOXYMETHYLCELLULOSE GIVING AQUEOUS SOLUTIONS OF LOW THIOXTROPY WHICH COMPRISES ETHERIFYING CELLULOSE WITH A COMPOUND SELECTED FROM THE GROUP CONSISTING OF MONOCHLORACETIC ACID AND THE ALKALI METAL SALTS THEREOF IN A 3-COMPONENT, 2-LIQUID PHASE REACTION MEDIUM IN WHICH ONE PHASE CONSISTS ESSENTIALLY OF A MIXTURE OF WATER AND A WATER-MISCIBLE ALIPHATIC ALCOHOL HAVING FROM 2 TO 4 CARBON ATOMS AND THE SECOND LIQUID PHASE CONSISTS ESSENTIALLY OF A LIQUID AROMATIC HYDROCARBN AND AN ADDITIONAL AMOUNT OF SAID WATER-MISCIBLE ALCOHOL WHEREIN ALKALI CELLULOSE IS FORMED BY TREATING THE CELLULOSE WITH AQUEOUS ALKALI IN SAID 3-COMPONENT SYSTEM AT A TEMPERATURE FROM ABOUT 15*C. TO 40*C. FOR AT LEAST 10 MINUTES, ADDING SAID ETHERIFYING AGENT TO SAID ALKALI CELLULOSE AT A TEMPERATURE FROM ABOUT 15*C. TO 45*C., MAINTAINING THIS TEMPERATURE WHILE MIXING FOR AT LEAST 5 MINUTES, THEN REGULATING THE TEMPERATURE TO FROM ABOUT 45*C. TO 75*C. UNTIL SUBSTANTIALLY COMPLETE CONSUMPTION OF THE ETHERIFYING AGENT HAS OCCURRED, THE ALCOHOL CONTENT OF THE TOTAL LIQUID PHASES BEING FROM ABOUT 30 TO 46% BY WEIGHT,THE WEIGHT RATIO OF WATER TO ALCOHOL BEING FROM ABOUT 0.15 TO 0.24 DURING SAID ETHERIFICATION AND THE CAUSTIC-TO-CELLULOSE RATIO BEFORE ADDITION OF THE ETHERIFYING AGENT IS FROM ABOUT 0.4 TO 1.0 BUT NEVER LESS THAN 2 MOLES OF CAUSTIC PER MOLE OF ETHERIFYING AGENT.