Processes for polymerization in aqueous suspension of vinyl chloride and manufacture of a solution of dialkyl peroxydicarbonate with short alkyl chains

摘要

The dialkyl peroxydicarbonates with short alkyl chains, are used for the aqueous suspension polymerization of vinyl chloride, in the form of a solution in a dialkyl alkanedicarboxylate. The preferred solvents are hexanedicarboxylates (adipates) derived from adipic acid and C6-C10 alkanols. The peroxydicarbonate concentration of the said solutions is generally 15-40% by weight. The process according to the invention produces vinyl chloride polymers of improved quality resulting in shaped articles exhibiting markedly fewer fisheyes. The invention also relates to a two-stage process for the manufacture of a solution of dialkyl peroxydicarbonates with short alkyl chains which is particularly suited for the aqueous suspension polymerization of vinyl chloride. According to this process an inorganic salt is used in the stage of manufacture of the peroxydicarbonate (first stage) and the latter is subsequently isolated by extraction by means of a water-insoluble solvent (second stage).