Basf Aktiengesellschaft

Peter Gawlik

Werner Balz

Karl Uhl

Herbert Motz

Roland Falk

Dieter Schaefer

Hans-Joerg Hartmann

The invention relates to a process for the manufacture of improved magnetic discs by applying a thin layer of a liquid dispersion of magnetic pigments and optionally further, non-magnetic, pigments in a binder mixture to a non-magnetic rigid base, and curing the magnetic coating which has been applied. The binder used is a mixture of polycondensates comprising 60 to 70% by weight of a solid curable polycondensate of 2,2-bis(4-hydroxyphenyl)-propane and epichlorohydrin having an epoxy equivalent weight from about 400 to 2,500 and a melting point from about 50.degree. to 150.degree. C, 10 to 30% by weight of a curable allyloxybenzene-formaldehyde condensate of the resol type with free methylol groups or with methylol groups etherified with a lower alcohol, and having a molecular weight of less than 1,000, and 10 to 30% by weight of a curable melamine-formaldehyde condensate with more than two methylol groups etherified with n-butanol or iso-butanol, and having a molecular weight of less than 2,500. A magnetic dispersion using such a binder allows the application of a firmly adhering magnetic coating, even in thicknesses of less than 4 .mu., to aluminum discs or pre-coated aluminum discs, and the magnetic coating produced has high resistance to mechanical wear.

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Ludwigshafen, Germany

Peter Gawlik