US 5,463,021 AGranted

Process for working up aqueous dispersions of fluorinated thermoplastic

AssigneeHoechst Aktiengesellschaft

InventorsGerhard Beyer, Reinhard Sulzbach, Eduard Wess, Rolf Hengel

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Abstract

The aqueous dispersions from the polymerization of fluorinated thermoplastics can be worked up to a high value product (e.g., substantially purified of cations resulting from the polymerization) in a continuous manner, if the cations are first removed from the aqueous dispersion, the dispersion is then compressed and decompressed through small openings, thereby being coagulated, the coagulated phase is washed on a filter and partially dewatered, subsequently broken up to give a free-flowing product and this is dried to the desired residual moisture content. Qualitatively high value products, which can be directly fed to a melt extruder, are thus obtained with high throughputs.

Claims13

Dependent claims

A process for working up aqueous dispersions of fluorinated thermoplastics which comprises

substantially replacing by hydrogen ions the cations in the aqueous dispersion which have resulted from the polymerization,
compressing the dispersion, optionally after dilution with water,
coagulating the compressed dispersion by decompressing it through one or more opening(s) small enough to provide coagulation, said compressing step being carried out at sufficient pressure to induce coagulation when said compressed dispersion is decompressed,
transferring the resulting coagulated phase, optionally after dilution with water and/or heating, onto a filter,
washing the product there,
dewatering the resulting product mechanically, and
breaking up the product to give a free-flowing product.

4 more elements

Dependencies are inferred from the claim text.