Patent · US Expired

Manufacture of gamma-iron (III) oxide

US4018882A · kind A · utility

3Cited by

5References

5Claims

0Family size

Assignee

BASF SE

Inventors

Eberhard Koester · Bischofswerda, DE
Gerd Wunsch · Speyer, DE
Eduard Schoenafinger
Hans H. Schneehage · Bad Dürkheim, DE
Helmut Jakusch · Bischofswerda, DE

Key dates

Filing date	Sep 25, 1975
Grant date	Apr 19, 1977
Priority date	—
Expiry date	Sep 25, 1995

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC01P2006/42
WIPO fieldAudio-visual technology
WIPO sectorElectrical engineering

Abstract

A process for the manufacture of acicular magnetic gamma-iron(III) oxide by reducing acicular alpha-iron(III) oxide to magnetite and then oxidizing it to gamma-iron(III) oxide, wherein the alpha-iron(III) oxide is treated with a water-soluble alkaline earth metal compound and an alkylphenol with one to three alkyl radicals, each of 4 to 24 carbon atoms, on the benzene nucleus. Gamma-iron(III) oxides manufactured in this way show better magnetic orientability in the binder-containing dispersion, and a higher coercive force than prior art magnetic pigments.

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