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. 06, 1987
Filed:
Apr. 16, 1986
Wilfried Burow, Krefeld, DE;
Helmut Printzen, Krefeld, DE;
Horst Brunn, Krefeld, DE;
Klaus Nollen, Krefeld, DE;
Bayer Aktiengesellschaft, Leverkusen, DE;
Abstract
Iron oxide yellow pigments having a silking effect .DELTA.E.sub.1 *, less than or equal to 0.5, and having color values which range for L* from 52-63, for a* from 8 to 14 and for b* from 40 to 48 CIELAB units are produced by a process by first, forming needle-shaped .alpha.-FeOOH yellow pigment nuclei in the presence of compounds containing the elements B, Al, Ga, Si, Ge, Sn or Pb present in a quantity of from 0.05 to 10% by weight, where the quantity is calculated as the tri- or tetra-valent oxides of the compounds and based on the .alpha.-FeOOH which is precipitated during nucleation, and second, growing iron oxide yellow pigments on the thus formed iron oxide yellow nuclei.