The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 18, 1983
Filed:
Feb. 28, 1980
Jurgen Kuhls, Burghausen, DE;
Eduard Weiss, Burghausen, DE;
Hoechst Aktiengesellschaft, Frankfurt, DE;
Abstract
Aqueous colloidal dispersions of fluorinated polymers can be concentrated, after adding a stabilizing emulsifier, to high solids contents by ultrafiltration over customary semi-permeable membranes if pumps which keep the dispersion free from contact with components which cause frictional forces are used for conveying the dispersion. A considerable proportion of the stabilizing emulsifier added and high proportions of the fluorine-containing emulsifier originally contained in the fluorinated polymer dispersion from the emulsion polymerization can be removed via the aqueous permeate. The fluorine-containing emulsifier can be recovered by a downwstream basic anion exchanger and the stabilizing emulsifier contained in the filtrate flowing out of the anion exchanger can be concentrated in this filtrate by reverse osmosis and optionally recycled into the ultrafiltration process. Fluorinated polymer dispersions which, in addition to having a high solids content, are distinguished by particularly low contents of fluorine-containing emulsifier and of stabilizing emulsifier can be obtained. The process can be applied to all known aqueous, colloidal dispersions of fluorinated homopolymers and copolymers.