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:
Nov. 10, 1987
Filed:
Jun. 09, 1986
Ernst Spietschka, Idstein, DE;
Manfred Urban, Wiesbaden, DE;
Hoechst Aktiengesellschaft, , DE;
Abstract
Process for the preparation of pigments of the anthanthrone series of the formula ##STR1## in which R.sub.1 and R.sub.2 denote chlorine, bromine or iodine atoms or C.sub.1 -C.sub.4 -alkoxy groups, having valuable properties, which comprises first converting the anthanthrones of the formula mentioned, in the form of the crude pigment, in an aqueous alkaline medium and at a pH>10, into the leucoform, precipitating the latter by adding inorganic or organic acids, reoxidizing the aqueous suspension of the leuco-form to give the anthanthrones and subjecting the resulting finely divided pre-pigments of the formula mentioned to a solvent finish.