Basf Aktiengesellschaft

Rudolf Sand

Werner Ostertag

Roland Falk

Dieter Schaefer

Peter Nagel

Hans Joerg Hartmann

Aribert Krug

Job Werner Hartmann

Karl Deimling

A process for polishing the ground surfaces of magnetic storage disks which consist of a rigid substrate provided on both sides with a firmly adhering magnetic coating consisting of a magnetic material finely dispersed in an organic polymer and conventional additives, by pressing felt rings or felt disks against the moving magnetic storage disk, to the surface of which an aqueous emulsion containing butyl acetate with or without butane-1,4-diol is applied.

Process for polishing the surfaces of magnetic storage disks

The invention relates to magnetic discs in which first a non-magnetic intermediate layer and then the magnetic coating are applied by conventional methods to an aluminum disc. The intermediate layer applied to the non-magnetic metallic carrier disc is a hard non-magnetic coating which can be polished and which consists of a dispersion of a pulverulent mixture of finely divided inorganic non-magnetic pigments having a Mohs' hardness of at least 7 in a binder which can be cured and which provides firm cohesion of the pigment particles and good adhesion thereof to the non-magnetic base disc, the pigment mixture containing at least 3 percent by weight of corundum powder having a particle size of from about 1 to 20.mu.u. Magnetic discs with very thin magnetic coatings which possess good magnetic and mechanical properties and whose thickness varies only minimally are thus produced in a simple manner.

Magnetic discs having metal support and a non-magnetic layer

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Willstaett, Germany

Rudolf Sand