Stabilization of chromium dioxide magnetic pigments

US4177317A · kind A · utility

Assignee

• BASF SE

Inventors

• Eduard Schoenafinger
• Paul Deigner · Bad Dürkheim, DE
• Eberhard Koester · Bischofswerda, DE
• Manfred Ohlinger · Bischofswerda, DE
• Dieter Schaefer
• Werner Stumpfi
• Juergen Amort · Troisdorf, DE
• Claus-Dietrich Seiler · Rheinfelden (Baden), DE
• Heinz Nestler · Troisdorf, DE
• Otto Ambros · Mannheim, DE

Key dates

• Filing date: May 20, 1977
• Grant date: Dec 4, 1979
• Expiry date: May 20, 1997

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/2995
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

Chromium dioxide magnetic pigments can be stabilized against the loss of their magnetic properties by treating them, in alcoholic aqueous suspension, with a silane or a hydrolysis product thereof, so that when the pigment is isolated from the suspension medium the particles bear at least partially hydrolyzed silane on their surfaces, and then drying the magnetic pigment at from 50.degree. to 200.degree. C.