Manufacture of cellulose esters of aliphatic acids

Claim 1

A PROCESS OF PREPARING AN EXTRUDED ARTICLE WHICH COMPRISES FILTERING A SOLUTION PREPARED BY ESTERIFYING CELLULOSE WITH AN ALIPHATIC ACID ANHYDRIDE CONTAINING FROM 2 TO 4 CARBON ATOMS IN THE MOLECULE IN THE PRESENCE OF AT LEAST SUFFICIENT ALIPHATIC ACID CONTAINING 2 TO 4 CARBON ATOMS IN THE MOLECULE TO DISSOLVE THE CELLULOSE ESTER AS IT IS FORMED, AND OF SULPHURIC ACID IN AMOUNT AT MOST 0.5% BY WEIGHT AS CATALYST, THE WHOLE OF THE SAID SULPHURIC ACID HAVING BEEN UNIFORMLY DISPERSED THROUGHOUT THE CELLULOSE IN THE COURSE OF AN ACTIVATING PRETREATMENT IN WHICH AN ALIPHATIC ACID CONTAINING 1 TO 4 CARBON ATOMS IN THE MOLECULE IS EMPLOYED, THE ESTERIFICATION BEING EFFECTED AT A TEMPERATURE WHICH REACHES AT LEAST 50*C. AND RECOVERING THE CELLULOSE ESTER UPON COMPLETION OF ESTERIFICATION AND NEUTRALIZATION OF THE CATALYST, WITHOUT REQUIRING ANY REMOVAL OF SULPHURIC ACID FROM CHEMICAL COMBINATION WITH THE ESTER, AND EXTRUDING THE FILTERED SOLUTION INTO A MEDIUM EFFECTIVE TO CAUSE EVAPORATION OF THE SOLVENT FROM THE SOLUTION.