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:
Oct. 10, 1995
Filed:
Sep. 15, 1993
Shivakumar B Hendi, Newark, DE (US);
Edward E Jaffe, Wilmington, DE (US);
Ciba-Geigy Corporation, Ardlsey, NY (US);
Abstract
A general method for the direct preparation of pigmentary quinacridone solid solutions is disclosed. The disclosed process comprises oxidizing a mixture of dihydroquinacridones directly to a pigmentary quinacridone solid solution wherein the oxidation is carried out by heating a reaction mixture comprising the dihydroquinacridone mixture, an alkali metal hydroxide, a water miscible organic solvent, water and effective mounts of an oxidizing agent and a particle growth inhibitor. In addition, an analogous process useful for the direct pigmentary synthesis of .alpha.-quinacridone is disclosed. The pigments prepared by the disclosed processes do not require additional particle-size reducing after treatments in order to be useful as pigments.