Shin-etsu Chemical Co., Ltd.

Norinobu Wada

Yoshihiro Shirota

Yoshitaka Okuno

Unreacted residual monomer is removed from an aqueous slurry of a vinyl chloride polymerizate by a method, according to which the monomer-containing aqueous slurry continuously fed to a plate column from its top runs down by way of a cyclone-type mist separator and through a plurality of perforated plates, coming into counter-current contact with steam which is blown into the column from its bottom and ascends through the same perforated plates, to dissipate the monomer in the form of vapors, and the steam carrying the dissipated monomer vapors having entered the mist separator is subjected to mist separation and heat exchange with the slurry fed, and the resulting steam is discharged out of the column, followed by condensation to recover the monomer. The slurry having reached the bottom of the column is transferred to a flush tank where it is quenched to generate steam which is then blown into the column for recycling.

Method for removing unreacted monomer from the aqueous dispersion of

The unreacted gaseous vinyl chloride monomer still remaining in a polymerization reactor from which the polymerizate has been removed can be discharged by blowing steam into the reactor from its top so that the gaseous monomer is pushed downward and moved out from the bottom of the reactor, followed by a conventional treatment for condensation. This method of discharge serves to put the reactor open to the ambient atmosphere without the emission of the unreacted monomer and, as such, solve the problems of the workers' health and environmental pollution.

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Ibaragi, Japan

Norinobu Wada