Patent ID: 7834110

Claim:
Process wherein two or more initiators are used to polymerize a mixture containing one or more monomers of which one is vinyl chloride monomer, wherein the one or more monomers are polymerized at a polymerization temperature using an initiator with a half-life of more than 1 hour at the polymerization temperature, and one or more additional initiators are added to the polymerization mixture at the same polymerization temperature when the pressure in the polymerization reactor is dropping due to the depletion of gas phase vinyl chloride monomer, and said additional initiators have a half-life of less than 1 hour at polymerization temperature, wherein addition of said one or more additional initiator is not before the pressure has become less than the pressure that was observed earlier at the same polymerization temperature, with the proviso that the polymer formed is not subject to radio frequency dielectric heating in the presence of additional organic initiator.