Vinylidene Chloride-Vinyl Chloride Copolymer Production

The process under analysis comprises three major sections: (1) Polymerization; (2) Monomers Recovery; and (3) Drying & Finishing.

Polymerization. Polymerization initiator, dispersing agent and additives required are dissolved in agitated vessels with demineralized water forming solutions which will be fed to the polymerization reactors. The vinylidene chloride monomer, vinyl chloride comonomer and the chemicals solutions prepared are fed to the polymerization reactors, along with hot demineralized water, which heats the reaction media to the polymerization reaction temperature. The polymerization is performed in batch mode at 60 °C under continuous agitation for between 8 and 24 hours until conversion of monomers reach about 90%. After polymerization, the slurry is transferred to the Monomers Recovery section, downstream.

Monomers Recovery. The polymer suspension from Polymerization is transferred to a stripper vessel where residual monomers are steam-stripped from the slurry at reduced pressure. Vinylidene chloride monomer and vinyl chloride comonomer are recovered and recycled to the polymerization. The polymer slurry is transferred to the Drying section downstream.

Drying & Finishing. The free-monomer polymer slurry is fed to an intermediate vessel for the homogenization of several batches. The polymer slurry is then passed through a rotary filter, what yields a wet PVDC cake with residual moisture content. The wet cake is fed to a rotary dryer, and subsequently over-dried in a fluidized-bed dryer. The dried polymer is finally packed in bags before being stored in warehouses located outside battery limits (OSBL).