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. 09, 1977
Filed:
Feb. 06, 1976
Manfred Mansmann, Krefeld, DT;
Wolfgang Rambold, Krefeld, DT;
Bayer Aktiengesellschaft, Leverkusen, DT;
Abstract
In the production of chromium oxide green pigment by heating a substantially stoichiometrically equivalent mixture of sodium dichromate dihydrate and an ammonium salt selected from the group consisting of the sulfate and chloride, the improvement which comprises dry mixing sodium dichromate dihydrate having a particle size less than 2 mm with the ammonium salt having a particle size less than about 0.5 mm, heating the resulting mixture over a period of about 15 minutes to a pigment-forming temperature of about 800.degree. to 1100.degree. C, calcining the mixture at a temperature in that range, and separating the formed pigment from the salts. To the mixture prior to heating there may be added sodium hydroxide solution, boron compounds such as borax and/or organic modifiers such as sawdust which improve the color and tinting strength of the resulting pigment. The pigments are brighter, and of higher tinting strength than heretofore produced.