Patent · US Expired

Improving the magnetic properties of gamma-iron (III) oxide

US4212903A · kind A · utility

24Cited by

4References

5Claims

0Family size

Assignee

BASF SE

Inventors

Georg Schnell
Fritz Hammon · Bischofswerda, DE
Manfred Ohlinger · Bischofswerda, DE

Key dates

Filing date	Feb 22, 1977
Grant date	Jul 15, 1980
Priority date	—
Expiry date	Feb 22, 1997

Classification

Technology area (CPC Y)Emerging Cross-Sectional Technologies
CPC primaryY10S428/90
WIPO fieldAudio-visual technology
WIPO sectorElectrical engineering

Abstract

The invention relates to a process for improving the magnetic properties, especially the remanent magnetization, of gamma-iron(III) oxide which can be used advantageously as the magnetic component in magnetic recording media exhibiting reduced print-through. For this purpose, a gamma-iron(III) oxide manufactured according to known processes is heated at temperatures of from 400.degree. to 700.degree. C., the magnetic pigment having basic compounds on the crystal surface during this heat treatment and retaining a pH value above 8 until heating is over. Gamma-iron(III) oxide magnetic pigments treated in this way are particularly suitable for the manufacture of low-noise magnetic recording media with high remanent magnetization and particularly low print-through.

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