Patent · US Expired

Iron oxide yellow pigments having a low silking effect and a process for production thereof

US4620879A · kind A · utility

11Cited by

7References

11Claims

0Family size

Assignee

BAYER HEALTHCARE LLC · DE

Inventors

Wilfried Burow · Krefeld, DE
Helmut Printzen · Krefeld, DE
Horst Brunn · Meerbusch, DE
Klaus Nollen · Krefeld, DE

Key dates

Filing date	Jul 11, 1984
Grant date	Nov 4, 1986
Priority date	—
Expiry date	Jul 11, 2004

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC01P2006/64
WIPO fieldBasic materials chemistry
WIPO sectorChemistry

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.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.