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. 20, 1998
Filed:
Sep. 09, 1996
Applicant:
Inventors:
Martin Schmidt-Radde, Beindersheim, DE;
Herbert Helfert, Frankenthal, DE;
Bernd Eck, Viernheim, DE;
Bernhard Maltry, Obrigheim, DE;
Assignee:
BASF Aktiengesellschaft, Ludwigshafen, DE;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C07D / ;
U.S. Cl.
CPC ...
548543 ; 548555 ;
Abstract
In a process for purifying N-vinylpyrrolidone by crystallization in a crystallizer, those surfaces of the crystallizer from which crystals grow during the crystallization are covered with an N-vinylpyrrolidone seed layer before the crystallization.