ph control in the emulsion polymerization of vinyl chloride

Claim 1

A PROCESS FOR THE POLYMERIZATION OF A MONOMERIC POLYMERIZABLE MATERIAL CONTAINING AT LEAST 50% BY WEIGHT OF VINYL CHLORIDE AT A PH OF FROM 7.0 TO 7.7 AT A TEMPERATURE OF FROM 30* C. TO 65* C. AND AT A PRESSURE OF FROM 50 T 150 P.S.I.G., WHICH COMPRISES ADDING PART OF THE MONOMERIC MATERIAL TO AN AQUEOUS MEDIUM CONTAINING PER 100 PARTS OF TOTAL MONOMER, FROM 0.05 TO 0.3 PARTS OF AN ALKALI METAL SULFATE OF A LONG CHAIN SATURATED ALIPHATIC COMPOUND CONTAINING FROM 10 TO 20 CARBON ATOMS AND FROM 0.01 TO 0.1 PART OF AN OXIDIZABLE SULFOXY COMPOUND, ADDING A DILUTE AQUEOUS SOLUTION CONTAINING FROM 0.001 TO 0.01 PART OF A WATER-SOLUBE POLYMERIZATION CATALYST TAKEN FROM THE GROUP CONSISTING OF AMMONIUM, POTASSIUM AND SODIUM PERSULFATES, SAID ADDITION BEING MADE DURING THE COURSE OF THE POLYMERIZATION REACTION CONCURRENTLY WITH THE ADDITION OF THE BALANCE OF THE MONOMER AND AT SUCH A RATE THAT THE REACTION TEMPERATURE VARIES BY NO MORE THAN 2* C., MAINTAINING A PRESSURE OF FROM 50 TO 150 P.S.I.G. IN THE REACTION VESSEL THROUGHOUT THE REACTION STOPPING THE ADDITION OF CATALYST COINCIDENTALLY WITH THE PRESSURE DROP AT THE END OF THE REACTION, AND CONTINUING THE HEATING OF THE REACTION MEDIUM FOR AT LEAST 15 MINUTES AFTER THE LAST CATALYST ADDITION, THE RATIO OF OXIDIZABLE SULFOXY COMPOUND TO CATALYST BEING AT LEAST AS GREAT AS 6:1 ON A MOLAR BASIS THROUGHOUT THE REACTION, THE TOTAL AMOUNT OF SAID CATALYST BEING CONTROLLED TO PROVIDE FROM 0.00006 TO 0.0006 PART OF AVAILABLE OXYGEN PER 100 PARTS OF MONOMER.