Process for producing hydroxyethoxycellulose

Claim 1

THE PROCESS OF PRODUCING HYDROXYDETHOXYCELLULOSE SUITABLE TO FORM STRONG FILAMENTS AND CLEAR TOUGH FILMS WHICH COMPRISES CONTINUOUSLY PASSING A SHEET OF CELLULOSE OF INDEFINITE LENGTH THROUGH AN OPERATION IN WHICH AN AQUEOUS SOLUTION OF SODIUM HYDROXIDE IS CONTINUOUSLY PASSED THROUGH THE SHEET IN SUCH VOLUME AS TO EFFECT UNIFORM ALKALIZATION, SAID SHEET BEING FORMED OF CELLULOSE HAVING RELATIVELY UNIFORM CHAIN LENGTHS, REMOVING MOST OF THE EXCESS AQUEOUS SOLUTION ADHEREING TO THE SHEET, PASSING THE CONTINUOUSLY MOVING SHEET OF ALKALIZED CELLULOSE INTO A CHAMBER IN WHICH ETHYLENE OXIDE GAS IS FORCED THROUGH THE MOVING SHEET OF ALKALIZED CELLULOSE TO EFFECT UNIFORM ETHERIFICATION WITH THE SUBSTITUTION OF FROM ABOUT 2% TO ABOUT 8% OF ETHYLENE OXIDE ON THE ALKALIZED CELLULOSE, THE UNIFORM ALKALIZATION AND ETHERIFICATION RESULTING IN HYDROXYETHOXYCELLULOSE WHICH IS SUBSTANTIALLY ALL SOLUBLE IN A 5% AQUEOUS SODIUM HYDROXIDE SOLUTION AT ABOUT 0*C. BUT SUBSTANTIALLY INSOLUBLE IN WATER, AND DISSOLVING SUBSTANTIALLY ALL THE HYDROXYETHOXYCELLULOSE IN A DILUTE AQUEOUS SOLUTION OF SODIUM HYDROXIDE AT A TEMPERATURE ABOVE THE FREEZING POINT OF THE SOLUTION.