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:
May. 23, 1978
Filed:
Apr. 08, 1976
Jakob Rademachers, Krefeld, DT;
Franz Hund, Krefeld, DT;
Ingo Pflugmacher, Meerbusch, DT;
Gerhard Winter, Krefeld, DT;
Bayer Aktiengesellschaft, Leverkusen, DT;
Abstract
In a two-stage process for producing black iron oxide pigments wherein an iron salt solution is alkalized in a first stage to precipitate about 55 to 70% of the iron, the solution is oxidized to convert the precipitate to goethite, the solution is further alkalized in a second stage to precipitate the balance of the iron, the precipitated iron II hydroxide is allowed to react with goethite to form magnetite, the improvement which comprises effecting the second stage in the presence of an inorganic ionic compound of at least one metal selected from the group consisting of copper, nickel, aluminum, chromium, titanium, zirconium and vanadium in about 0.05 to 5% calculated as metal based on the weight of the final pigment. The resulting pigment is of high color intensity, narrow grain distribution range and pronounced magnetite structure.