Method of making cellulose esters in the form of small, dense, spherical particles

Claim 1

A PROCESS FOR MAKING SMALL, SUBSTANTIALLY NONPOROUS, SUBSTANTIALLY SPHERICAL PRARTICLES OF LOWER FATTY ACID ESTERS OF CELLULOSE WHICH COMPRISES DISSOLVING THE CELLULOSE ESTER IN AN ORGANIC SOLVENT COMPRISING AT LEAST TWO COMPONENTS, ONE OF SAID COMPONENTS BEING INFINITELY SOLUBLE IN WATER AND ANOTHER OF SAID COMPONENTS BEING INSOLUBLE TO MODERATELY SOLUBLE IN WATER IN AN AMOUNT UP TO ABOUT 30% BY WEIGHT AT 20*C., SAID MIXED SOLVENT BEING SOLUBLE IN WATER TO THE EXTENT OF ABOUT 10 TO 50 PARTS IN 100 PARTS OF WATER AT 20*C., DISPERSING THE CELLULOSE ESTER SOLUTION IN WATER IN THE PRESENCE OF A COLLOIDING AGENT AND A WATER-SOLUBLE SALT, THE WATER BEING PRESENT IN AMOUNT SUFFICIENT TO FORM AN OIL-IN-WATER EMULLSION, THE COLLOIDING AGENT BEING PREFERENTIALLY SOLUBLE IN THE WATER AND BEING PRESENT IN AMOUNT SUFFICIENT TO INCREASE SUBSTANTIALLY THE VISCOSITY OF THE WATER PHASE, THE SALT BEING PRESENT IN AN AMOUNT LESS THANT THAT WHICH CAUSES PRECIPITATION OF THE COLLOIDING AGENT, REMOVING THE ORGANIC MIXED SOLVENT FROM THE DISPERSED PARTICLES, THE TEMPERATURE OF THE EMULSION FOR SUBSTANTIAL SOLVENT REMOVAL BEING UP TO THE BOILING POINT OF THE SOLLVENT AND BELOW THE BOILING POINT OF WATER, AND SEPARATING THE PARTICLES FROM THE WATER.