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:
Oct. 28, 2003
Filed:
Mar. 10, 2003
Applicant:
Inventors:
Torsten Hagen, Düsseldorf, DE;
Friedhelm Kämper, Krefeld, DE;
Daniel Koch, Duisburg, DE;
Rudolf Uchdorf, Krefeld, DE;
Stefan Wershofen, Mönchengladbach, DE;
Assignee:
Bayer Aktiengesellschaft, Leverkusen, DE;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C07C / ; C07C / ; C07C / ; C07C / ; C07C / ;
U.S. Cl.
CPC ...
C07C / ; C07C / ; C07C / ; C07C / ; C07C / ;
Abstract
Polyisocyanates of the diphenyl methane series having reduced color values are obtained by a) reacting aniline and formaldehyde in the presence of an acid catalyst to form a polyamine, b) neutralizing the reaction mixture containing polyamine with a base, c) separating the neutralized mixture into the aqueous and the organic phases, d) adding a base to the organic phase and then e) phosgenating the resulting polyamine to produce the corresponding polyisocyanate.