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:
Aug. 28, 1990
Filed:
Apr. 14, 1988
Applicant:
Inventor:
Karl Schmeidl, Ludwigshafen, DE;
Assignee:
BASF Aktiengesellschaft, Ludwigshafen, DE;
Primary Examiner:
Int. Cl.
CPC ...
C09B / ; C09B / ; C09B / ; D21H / ;
U.S. Cl.
CPC ...
534676 ; 534575 ; 534576 ; 534887 ;
Abstract
Stable solutions of azo dyes obtained by diazotizing and coupling m-phenylenediamine or derivatives thereof are prepared after the reaction has ended by treating the resulting reaction mixture with from 0.1 to 1.2 moles of formic acid, based on 1 mole of m-phenylenediamine, at from 60.degree. C. to the boiling point of the reaction mixture.