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:
Apr. 19, 1977
Filed:
Dec. 21, 1973
Ernst Spietschka, Oberauroff, Taunus, DT;
Siegfried Schiessler, Frankfurt am Main, DT;
Wolfgang Tronich, Frankfurt am Main, DT;
Hoechst Aktiengesellschaft, Frankfurt (Main), DT;
Abstract
A process for the preparation of highly pure organic pigments which comprises converting organic dyestuffs having various degrees of purity into dyestuff salts capable of being isolated by means of suitable acids which dissolve the impurities contained in the dyestuff, separating them from the acid, recovering the dyestuffs in pure form from the dyestuff salts by the action of water and subjecting the isolated dyestuff in aqueous organic or aqueous-organic medium to a mechanical fine dispersion. By this process the dyestuff formed by the decomposition of the dyestuff sulfate is obtained in highly pure form and can extremely well be brought into a finely dispersed form so that it can be brought into pigment form already by short-time grinding. During the preparation and isolation of the dyestuff sulfate the sulfuric acid is obtained in such a high concentration that it can be regenerated in an economical manner and any ecological charge is avoided.