Basf Aktiengesellschaft

Werner Stumpfi

Eberhard Koester

Paul Deigner

Kurt Schmidts

Gerd Wunsch

Dietmar Pfefferkorn

Horst Fitterer

Norbert Kreimes

Gunter Bettinger

Friedrich Engel

Norbert Schaffer

Manfred Ohlinger

Claus-Dietrich Seiler

Werner Steck

Heinz Nestler

Karl Uhl

Dieter Schaefer

Eduard Schoenafinger

Hans Henning Schneehage

Otto Ambros

Juergen Amort

The invention relates to a hub for magnetic tape cassettes, especially compact cassettes, and to magnetic tape cassettes possessing such hubs. In a first embodiment, spring means are provided on the inner periphery of the hub and exert radial pressures on the drive spindle, the spring means consisting, for example, of sprung teeth. In a further embodiment, the teeth have a spring rate of from about 1 P/mm to 40 P/mm. In another embodiment, the hub consists of an inner part and an outer part which can be coupled to one another and between which there is some play after coupling. A large number of specific examples of hubs are given to show possible shapes and arrangements of the teeth, and to show the types of material that can be used. In an advantageous embodiment, the inner part of the two-part hub can also be made a part of the drive spindle on the recorder, which inner part can be coupled with the outer part when the drive spindle enters the cassette.

Hub for magnetic tape cassettes, especially compact cassettes, and

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.

Stabilization of chromium dioxide magnetic pigments

A process for the manufacture of acicular ferromagnetic metal pigments containing iron, having a reduced field strength distribution and a steeper residual magnetization curve, by applying an alkaline earth metal cation and an organic compound having at least one group capable of forming a chelate to appropriate acicular iron oxides and then reducing the treated oxides.

Manufacture of acicular ferromagnetic metal pigments containing iron

A process for the manufacture of magnetic materials containing a phase A with a ferromagnetic spin system, of composition Co.sub.x Ni.sub.1.sub.-x and a phase B with an antiferromagnetic spin system of composition (CoO).sub.x (NiO).sub.1.sub.-x , with values of x from 0.05 to 0.96, the phases A and B showing exchange interaction. The materials are manufactured by surface oxidation of starting materials having a ferromagnetic layer, at least on the surface but optionally extending deeper, of composition A, to produce the antiferromagnetic phase B, nitrous oxide being used as the oxidant. Magnetic materials thus obtained have an asymmetrical hysteresis loop, which manifests itself at different temperatures, namely the particular Neel temperature of the phase B, which depends on the composition of the phases which varies in accordance with the values of x.

Manufacture of magnetic materials which exhibit exchange anisotropy

Growing community of inventors

Ludwigshafen, Germany

Werner Stumpfi