Method for preparing aqueous dispersions of high molecular weight olefin polymers

Claim 1

A PROCESS FOR PREPARING STABLE AQUEOUS COLLOIDAL DISPERSIONS OF SOLID HIGH MOLECULAR WEIGHT POLYMERS MADE FROM OLEFINICALLY UNSATURATED HYDROCARBONS CONTAINING 2 TO 10 CARBON ATOMS AND COPOLYMERS OF SAID HYDROCARBONS WITH COPOLYMERIZABLE UNSATURATED MONOMERS WHICH COMPRISES THE STEPS OF: (A) FEEDING THE SOLID POLYMER WHICH IS TO BE DISPERSED INTO A MULTIZONE EXTRUDER HAVING, IN SEQUENCE, A ZONE FOR MELTING, PUMPING AND METERING THE POLYMER, A MIXING ZONE AND A DISCHARGE ZONE; (B) MELTING, PUMPING AND METERING THE POLYMER AND CONTINUOUSLY PASSING IT TO THE MIXING ZONE; (C) INJECTING INTO THE MIXING ZONE A PRESSURIZED LIQUID MIXTURE CONSISTING OF A WATER-IMMISCIBLE SOLVENT FOR THE POLYMER AND AN AQUEOUS SOLUTION OF AN EMULSIFYING AGENT IN WHICH MIXTURE THE RATIO OF AQUEOUS SOLUTION TO WATER IMMISCIBLE SOLVENT IS FROM 1:4 TO 1:10 BY WEIGHT; (D) ADMIXING THE POLYMER, THE WATER-IMMISCIBLE SOLVENT THEREFOR, AND THE AQUEOUS SOLUTION OF EMULSIFIER IN THE MIXING ZONE IN WHICH THE RATIO OF THE LIQUID MIXTURE TO THE POLYMER IS FROM 2.5:1 TO 6:1 BY WEIGHT; (E) PASSING THE RESULTING EMULSION MIXTURE THROUGH THE DISCHARGE ZONE INTO A TEMPERATURE CONTROL AND MIXING ZONE, FURTHER MIXING THE EMULSION WHILE MAINTAINING THE TEMPERATURE AT FROM ABOUT 70* TO ABOUT 120*C. AND THEN (F) VOLATILIZING THE WATER-IMMISCIBLE SOLVENT FROM THE EMULSION, LEAVING A COLLOIDAL DISPERSION OF THE SOLID POLYMER IN AQUEOUS MEDIUM.