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:
Nov. 04, 2003
Filed:
Apr. 12, 2002
Applicant:
Inventors:
Stephan Führer, Kastl, DE;
Klaus Hintzer, Kastl, DE;
Gernot Löhr, Burgkirchen, DE;
Werner Schwertfeger, Altötting, DE;
Assignee:
3M Innovative Properties Company, St. Paul, MN (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
C07C 5/315 ; C07C 5/316 ; C07C 1/738 ;
U.S. Cl.
CPC ...
C07C 5/315 ; C07C 5/316 ; C07C 1/738 ;
Abstract
Fluorinated emulsifiers, in particular, perfluorooctanoic acid are bound to anionic exchange resins for the purification of aqueous effluent from the production of fluoropolymers. Said emulsifiers may be quantitatively eluted from the exchanger with a water-miscible organic solvent, containing a small amount of ammonia. It is of advantage to distil off the ammonia containing solvent, recycle the emulsifier to a further polymerization and recycle the ammoniacal solvent for elution. Addition of alkalis improves the elution efficiency.