Basf Aktiengesellschaft

Hans Reichert

Peter Rudolf

August Lehner

Manfred Ohlinger

Norbert Schneider

Werner Grau

Guenter Vaeth

Ludwig Kreitner

Friedrich Sommermann

Horst Autzen

Joachim Werther

Friedrich R Faulhaber

Gerd Erhardt

Magnetic recording media are produced by preparing a dispersion of anisotropic magnetic materials in solution in an organic binder using dispersants and further conventional additives, applying the dispersion in the form of a layer onto a nonmagnetic substrate and solidifying the applied magnetic layer, by a process in which a cylindrical grinding chamber is used which is provided with an anchor stirrer or helical stirrer and contains grinding media whose specific gravity is lower than that of the magnetic material.

Production of magnetic recording media

A process for the preparation of acicular gamma-iron(III) oxide of high coercive force by reducing acicular iron(III) oxide hydroxide, as it is being passed continuously through a furnace having two or more heating zones at from 190.degree. to 700.degree. C., by means of a gas mixture which is produced by passing a stream of inert gas, heated to above 250.degree. C., through an organic substance also heated to above 250.degree. C. in a vessel, and, on introduction into the furnace, is first brought into contact with the .alpha.-iron(III) oxide formed from the iron(III) oxide hydroxide by elimination of water in the first heating zone of the furnace at from 190.degree. to 250.degree. C., the .alpha.-iron(III) oxide thereby being converted to magnetite which is subsequently oxidized with an oxygen-containing gas at from 150.degree. to 400.degree. C., to give gamma-iron(III) oxide.

Preparation of acicular gamma-iron(III) oxide of high coercive force

Growing community of inventors

Oberkirch, Germany

Hans Reichert