Treatment of cellulose esters

Claim 1

IN A PROCESS FOR THE PRODUCTION OF CELLULOSE ACETATE OF IMPROVED MOLDING PROPERTIES WHEREIN THE CELLULOSE ACETATE EMPLOYED IS PREPARED BY ESTERIFYING CELLULOSE WITH ACETIC ANHYDRIDE IN THE PRESENCE OF AN ACID ESTERIFICATION CATALYST AND THE CELLULOSE IS RIPENED TO THE DESIRED ACETYL VALUE, THE STEPS WHICH COMPRISE DILUTING THE RIPENED CELLULOSE ACETATE SOLUTION WITH 70 TO 110% BY WEIGHT OF 20 TO 50% AQUEOUS ACETIC ACID, FILTERING THE DILUTED SOLUTION OF RIPENED CELLULOSE ACETATE, PRECIPITATING THE RIPENED CELLULOSE ACETATE FROM THE FILTERED SOLUTION, STABILIZING THE PRECIPITATED CELLULOSE ACETATE BY HEATING THE LATTER FOR 1/2 TO 6 HOURS AT A SUPERATMOSPHERIC PRESSURE OF 10 TO 85 POUNDS PER SQUARE INCH WITH FROM 10 TO 20 VOLUMES OF AN AQUEOUS MEDIUM OF LESS THAN 5 PARTS PER MILLION ALKALINITY, AND SUBJECTING THE STABILIZED CELLULOSE ACETATE TO EXTRACTION WITH AQUEOUS ETHYL ALCOHOL AT A TEMPERATURE ABOVE 30* C.