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:
Mar. 16, 1993
Filed:
Apr. 30, 1991
Applicant:
Inventor:
Wolfgang Rieper, Frankfurt am Main, DE;
Assignee:
Hoechst AG, Frankfurt am Main, DE;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C09B / ; C09B / ; C09D / ; D06P / ;
U.S. Cl.
CPC ...
534579 ; 534581 ; 534582 ; 534747 ;
Abstract
The industrial preparation of C.I. Pigment Yellow 81 by conventional coupling methods has the disadvantage that traces of polychlorinated biphenyls are formed in the course of the reaction of the two components. The invention now provides that the addition of quaternary dialkyldiallylammonium compounds during the azo coupling will decisively suppress the PCB-forming secondary reactions during the pigment synthesis.