Polymerization of vinyl esters

Claim 1

IN THE PROCESS OF POLYMERIZING PARTICLES OF A VINYL ESTER OF A C2-C18 MONOCARBOXYLIC ALIPHATIC ACID SUSPENDED AS THE DISPERSED PHASE IN WATER CONTAINING POLYVINYL ALCOHOL AS A DISPERSANT AND A WATER SOLUBLE CHAIN TRANSFER AGENT SELECTED FROM THE GROUP CONSISTING OF ACETALDEHYDE PROPIONALDEHYDE, AND BUTYRALDEHYDE FOR DECREASING THE AVERAGE MOLECULAR WEIGHT OF THE RESULTING POLYMERIZED ESTER, THE IMPROVEMENT WHICH COMPRISES INTRODUCING INTO THE SAID SUSPENSION A LIPOPHYLIC ORGANIC PEROXIDE AS AN INITIATOR OF POLYMERIZATION WITHIN THE SUSPENDED PARTICLES, HYDROGEN PEROXIDE AS A HYDROPHYLIC INITIATOR OF POLYMERIZATION OF THE EXTERIOR SURFACES OF THE SAID PARTICLES, AND A WATER SOLUBLE ALKALI, WARNING THE RESULTING MIXTURE TO CAUSE POLYMERIZATION AT A TEMPERATURE NOT ABOVE BOILING UNDER THE PREVAILING PRESSURE, AND ADDING ADDITIONAL PORTIONS OF THE SAID ALKALI IN AMOUNTS TO MAINTAIN THE PH OF THE MIXTURE BETWEEN PH 4.5 AND 10 AT ALL TIME DURING THE POLYMERIZATION, THE PROPORTIONS USED BEING APPROXIMATELY AS FOLLOWS BY WEIGHT: 100 PARTS OF THE VINYL ESTER, WATER 25-1000 PARTS, ORGANIC PEROXIDE 0.02-2 PARTS, HYDROGEN PEROXIDE 0.0003-0.3 PART ON THE ANHYDROUS BASIS, POLYVINYL ALCOHOL 0.04%-5% OF THE WEIGHT OF THE WATER, AND ALKALI IN AMOUNT OF ESTABLISH THE PH OF THE AQUEOUS PHASE INITIALLY ABOVE 7.