Patent · US Expired

Manufacture of gamma-iron(III) oxide

US4071610A · kind A · utility

10Cited by

8References

2Claims

0Family size

Assignee

BASF SE

Inventors

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

Key dates

Filing date	Apr 19, 1976
Grant date	Jan 31, 1978
Priority date	—
Expiry date	Apr 19, 1996

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 gamma-iron(III) oxide, in which the non-magnetic, acicular iron(III) oxide is treated with a solution of a compound of the formula I ##STR1## where R.sup.1 and R.sup.2 are ##STR2## or O--R.sup.5, R.sup.3 is H, OH, ##STR3## or O--R.sup.5, R.sup.4 is alkyl or cycloalkyl of 1 to 16 carbon atoms and the R.sup.4 's may be identical or different, and R.sup.5 is alkyl, cycloalkyl or aralkyl of 3 to 18 carbon atoms, and is then converted to gamma-iron(III) oxide by reduction to magnetite, followed by oxidation. The gamma-iron(III) oxide obtained is distinguished by a high coercive force and improved magnetic orientation when used as a magnetic pigment for the manufacture of magnetic recording media.

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