Patent · US Expired

Magnetic iron oxide pigments and a process for their preparation

US4923519A · kind A · utility

6Cited by

8References

12Claims

0Family size

Assignee

BAYER HEALTHCARE LLC · DE

Inventors

Fritz Rodi · Moers, DE
Peter Kiemle · Uerdingen, DE
Aloys Eiling · Bochum, DE
Hendrik Kathrein · McMurray, US

Key dates

Filing date	Aug 31, 1987
Grant date	May 8, 1990
Priority date	—
Expiry date	Aug 31, 2007

Classification

Technology area (CPC Y)Emerging Cross-Sectional Technologies
CPC primaryY10T428/2991
WIPO fieldAudio-visual technology
WIPO sectorElectrical engineering

Abstract

Magnetic iron oxide pigments having a monomolecular coating of a cobalt compound useful in magnetic signal recordings having a dependence of coercivity on temperature in the temperature range of from 76 K to 298 K of less than 0.13 kA/mK and having a coercivity on powder compressed to 0.9 g/cm.sup.3 of greater than 51 kA/m are prepared applying a preliminary coating of Fe.sub.3 O.sub.4 or a bertholloid compound to a magnetic iron oxide core material having the composition FeO.sub.x where x is a number from 1.33 to 1.55 and then covering the preliminary coating with a cobalt compound.

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