Hoechst Aktiengesellschaft

Franz Botsch

Christoph Heinze

Horst Wolff

Helmut Braun

Helmut Kraus

Karl H Wallhausser

Walter Fink

Friedrich Heller

In aqueous dispersions on the basis of polyvinyl chloride the content of residual monomers is reduced by the countercurrent method by contacting the rapidly moved surface of the dispersion with secluded intensely mixed gas atmospheres in several successive chambers. To carry out the process a device is used which permits to obtain under mild conditions residual monomer contents of 10 ppm and therebelow.

Process and device for continuously treating with gases aqueous

A process for the continuous preparation of vinyl chloride polymers containing at least 85 weight percent of polymerized vinyl chloride units in an aqueous emulsion in the presence of at least one water soluble catalyst and 1.5 to 3.5 weight percent (calculated on the monomer(s)) of at least one water soluble salt of an aliphatic, saturated monocarboxylic acid having the formula ##STR1## wherein R.sub.1 and R.sub.2 are equal or different each representing a saturated, branched or unbranched alkyl radical having 1 to 5 carbon atoms or of at least one of said water soluble salt in mixture together with at least one known emulsifier being an organic compound containing sulfonic acid-groups. The resulting polymers show an equally excellent thermostability in mixture with one of a multiplicity of known stabilizers especially of the lead-, tin- or barium/cadmium type.

Process for the continuous manufacture of vinyl chloride polymers

Polymer dispersions are subject to a spray treatment to reduce the monomer content thereof. The dispersions are sprayed against the wall of the vessel by means of at least one spray nozzle. The residual monomer content of polymer dispersions is further reduced by spraying them in at least two series connected vessels, conducting the escaping gaseous constituents in one direction and the dispersion in opposite direction from one vessel to the next. The process is little liable to troubles and ensures a very effective monomer removal without thermal damage of the polymer.

Process for the manufacture of vinyl chloride polymer dispersions with a

Preserved synthetic resin dispersions and products made therefrom are provided which contain N-substituted maleic imide derivatives as a preservative.

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Burgkirchen, Germany

Franz Botsch