Process for the chlorination of polyvinyl chloride

Claim 1

IN THE METHOD FOR CHLORINATING PARTICULATE POLYVINYL CHLORIDE RESIN COMPOSED OF PARTICLES WITHIN THE RANGE OF FROM ABOUT 0.5 MICRON TO ABOUT 200 MICRONS COMPRISING THE STEPS OF PREPARING A SUSPENSION OF 100 PARTS BY WEIGHT OF THE POLYVINYL CHLORIDE IN AAT LEAST ABOUT 130 PARTS BY WEIGHT OF LIIQUID AQUEOUS MEDIUM, SAID SUSPENSION CONTTAINING FROM ABOUT 15 TO ABOUT 100 PARTS BY WEIGHT OF A HYDRO-CHLOROMETHYLENE COMPOUND TO SERVE AS A SWELLING AGENT F OR THE SUSPENDED POLYVINYL CHLORIDE RESIN, SUBSTANTIALLY SATURATING THE LIQUID AQUEOUS MEDIUM OF THE SUSPENSION WITH GASEOUS CHLORIDE, INDUCING THE CHLORIRNATION REACTION BETWEEN THE CHLORIDE AND THE POLYVINYL CHLORIDE IN SAID SUSPENSION, MAINTAINING AN EXCESS OF DISSOLVED CHLORINE IN SAID SUSPENSION OVER THAT MOMENTARILY REACTING WITH THE SUSPENDED RESIN, TERMINATING THE REACTION WHEN THE DESIRED AMOUNT OF CHLORINATION OF THE RESIN HAS BEEN ACHIEVED, SEPARATING THE HYDRO-CHLORO-METHYLENE-SWOLLEN CHLORINATED POLYVINYL CHLORIDE RESIN PRODUCT FROM THE AQUEOUS MEDIUM, NEUTRALIZING SAID PRODUCE, AND SEPARATING THE HYDROCHLOROMETHYLENE FROM SAID PRODUCT; THE IMPROVEOMENT WHICH COMPRISES ADMISING WITH SAID SUSPENSION OF POLYVINYL CHLORIDE RESIN IN LIQUID AQUEOUS MEDIUM PRIOR TO THE CHLORINATION THEREOF FROM ABOUT 0.2 PART TO ABOUT 5 PARTS OF COLLODOIAL SILICEOUS MATERIAL SELECTED FROM THE GROUP CONSISTING OF COLLOIDAL SILICA, COLLOIDAL POLYVALENT INORGANIC SILICATES.