Hoechst Aktiengesellschaft

Eberhard Tzschoppe

Manfred Engelmann

Heinz Klippert

Jurgen Weinlich

Stratos Paschalis

Ju/ Rgen Weinlich

The process is described for the continuous suspension polymerization of vinyl chloride in aqueous phase, in which the polymerization mixture is subjected, in 2 zones, to treatment employing different process parameters in respect of final conversion, dwell time, number of theoretical cascade stages and stirrer power applied. This procedure gives, at good space-time yields, very uniform products which have a narrow particle size distribution, a high bulk density, good flow and a low speck count. In spite of using standard kettle material, only a very low formation of deposit on the kettle walls is observed.

Continuous process for the production of vinyl chloride polymers in

In the manufacture of polymer suspensions, good spacetime yields, a narrow particle size distribution and good polymer properties are obtained in a relatively uncomplicated apparatus which includes a plurality of reactors having a length/diameter ratio of at least 4, the first reactor standing vertically and the others approximately horizontally. Plug flow of the polymerization mixture is maintained in the reaction zones provided by the reactors. In the first such zone, up to 10% of the polymerization is carried out, with agitation, preferably at a stirring energy per unit volume of 0.1 to 5 kWm.sup.-3. Wall encrustation is substantially prevented, particularly in the second reaction zone, through the use of smooth, non-metallic surfaces in the zone.

Continuous process and device for the manufacture of a vinyl chloride

The present invention provides vinyl chloride polymers having a reduced content of residual monomer. They are obtained by treating with steam a product moist with water at a temperature of from 90.degree. to 125.degree. C under a pressure of from 400 to 1,600 mm Hg. The invention also provides an apparatus to carry out the steam treatment of the moist polymer. The treated polymers have a residual vinyl chloride content down to less than 0.001% by weight.

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Burgkirchen, Germany

Eberhard Tzschoppe