Patent · US Expired

Preparation and use of iron magnetic pigments

US4631090A · kind A · utility

7Cited by

0References

14Claims

0Family size

Assignee

BAYER HEALTHCARE LLC · DE

Inventors

Rolf Naumann · Krefeld, DE
Lutz Leitner · Krefeld, DE
Jakob Rademachers · Krefeld, DE
Gunter Buxbaum · Krefeld, DE

Key dates

Filing date	May 31, 1985
Grant date	Dec 23, 1986
Priority date	—
Expiry date	May 31, 2005

Classification

Technology area (CPC H)Electricity
CPC primaryH01F1/065
WIPO fieldElectrical machinery, apparatus, energy
WIPO sectorElectrical engineering

Abstract

A magnetic pigment consisting essentially of iron, having an X-ray crystallite size with the 110 reflex of from 14 to 22 nm, a coercive force from 55 to 88 kA/m and a switching field distribution of the oriented pigment particles of less than 0.55 is produced by precipitating an iron (II)-salt with a super-stoichiometric quantity of an aqueous alkali metal carbonate solution and oxidizing it to produce .alpha.-FeOOH, .gamma.-Fe.sub.2 O.sub.3, Fe.sub.3 O.sub.4 or betholoid iron oxides, subsequently reducing it to the metal, and providing the iron oxides or oxide hydroxides with an inorganic protection from sintering at the latest during reduction.

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