Production of organic acid esters of cellulose

Claim 1

IN A PROCESS FOR THE PREPARATION OF CELLULOSE ACETATE FROM CELLULOSIC MATERIAL, THE STEPS WHICH COMPRISE SUBJECTING THE CELLULOSIC MATERIAL TO A MULTI-STAGE PRETREATMENT PRIOR TO ESTERIFICATION, ONE STAGE OF SAID PRETREATMENT COMPRISING THE ADDITION TO THE CELLULOSIC MATERIAL OF FROM ABOUT 30 TO 40 PARTS BY WEIGHT OF ACETIC ACID FOR EACH 100 PARTS BY WEIGHT OF ACETIC ACID FOR EACH PRESENCE OF FROM ABOUT 4 TO 7 PARTS BY WEIGHT OF WATER FOR EACH 100 PARTS BY WEIGHT OF CELLULOSIC MATERIAL, AND ANOTHER STAGE OF SAID PRETREATMENT COMPRISING THE ADDITION TO THE CELLULOSIC MATERIAL AFTER AN INTERVAL OF AT LEAST ABOUT 3 MINUTES OF FROM ABOUT 150 TO 300 PARTS BY WEIGHT OF ACETIC ACID AND FROM ABOUT 3 TO 15 PARTS BY WEIGHT OF SULFURIC ACID FOR EACH 100 PARTS BY WEIGHT OF CELLULOSIC MATERIAL WITHOUT DISPLACING ANY OF THE ACETIC ACID CONTAINED IN THE CELLULOSIC MATERIAL, AND ACETYLATING THE PRETREATED CELLULOSIC MATERIAL WITHIN A PERIOD OF LESS THAN ABOUT 15 MINUTES AFTER THE ADDITION THERETO OF THE ACETIC ACID AND SULFURIC ACID.