Patent ID: 7132485

Claim:
An essentially vinyl chloride-free suspension polymerization process for polymerizing styrene monomer, or a mixture of monomers comprising styrene, comprising the step of continuously or semi-continuously dosing an initiator selected from the group consisting of peroxydicarbonates, peroxycarbonates, peroxyesters, peroxyketals, diacylperoxides, dialkylperoxides, azo-initiators, ketone peroxides, which initiators may be functionalized, and mixtures thereof, from the point in time at which none of the monomer has been polymerized until at least 70% of all the monomer is polymerized, to the reaction mixture at the polymerization temperature, wherein at least one initiator that is dosed has a half-life of 60 minutes or less at said polymerization temperature.