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:
Jul. 12, 1977
Filed:
Jan. 28, 1976
Josef Landler, Hofheim, Taunus, DT;
Erhard Worfel, Hattersheim, am Main, DT;
Hoechst Aktiengesellschaft, Frankfurt am Main, DT;
Abstract
A new and very advantageous Process had been found for the preparation of azo dyestuffs by diazotation and coupling in which the synthesis is carried out without the hitherto usual addition of an acid, with the proviso that at least one of the diazo and coupling components contains at least one acid group. Besides the saving of reaction material and subsequently of alkali for neutralization of the reaction medium and isolation of the dyestuff, highly concentrated solutions of the dyestuff and salt-free or practically salt-free dyestuffs can be obtained, and waste-water is no longer charged with big amounts of salts.