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:
May. 11, 1976
Filed:
Aug. 31, 1973
Joseph Del Pico, Brockton, MA (US);
Shmuel Sternberg, Waltham, MA (US);
Abcor, Inc., Cambridge, MA (US);
Abstract
A process of concentrating an aqueous polyvinyl-chloride emulsion employing a membrane device comprising a feed zone and a permeate zone, the zones separated by an ultrafiltration semipermeable membrane, which process comprises: introducing the polyvinyl-chloride emulsion to be concentrated into the feed zone; removing a concentrated polyvinyl-chloride emulsion from the feed zone and removing an aqueous fraction from the permeate zone; interrupting the process of concentration periodically when the flux rate of the process falls below a desired flux rate value; and contacting the semipermeable membrane with a solution containing a solvent, such as tetrahydrofurane, for the polyvinyl-chloride for a time sufficient to restore the flux value to its desired level, the semipermeable membrane employed characterized by being solvent-resistant to the solvent employed in contacting the membrane.