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AssigneeChemische Werke Huels Aktiengesellschaft
InventorsJosef Kalka, Bernhard Hentschel, Jurgen Ziebarth
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In a process for removing monomeric impurities from an aqueous dispersion of homopolymers or copolymers of vinyl chloride having a surface tension below 60 dyn/cm. by treatment with steam while avoiding foam formation by a rapid lowering of the pressure at high flow velocities, the improvement which comprises: (a) continuously mixing said dispersion in a flow pipe with steam at a steam pressure of 800-4660 millibars for an average residence time of about 0.01-5 seconds; (b) continuously passing the resultant admixture from said flow pipe at a velocity of at least 30 meters per second directly to a degasification vessel having a pressure of 133-660 millibars; and (c) continuously recovering a polymer product containing less than 20 p.p.m. residual monomer impurities therefrom.
In a continuous process for removing monomeric impurites from an aqueous dispersion of homopolymers or copolymers of vinyl chloride having a surface tension below 60 dyn/cm. by treatment with steam while avoiding foam formation by a rapid lowering of the pressure at high flow velocities, the improvement which comprises:
Dependencies are inferred from the claim text.