| 摘要 |
PURPOSE:To enable effective prevention of electrification of a magnetic recording medium without deteriorating the electromagnetic conversion characteristic thereof owing to addition of a conductive material thereto as in the conventional practice by forming the film consisting of a non-magnetic metal having a specific value or above of oxidation-reduction potential on the surface of magnetic powder. CONSTITUTION:The magnetic powder prepd. by subjecting oxide magnetic powder such as gamma- Fe2O3, Co-contg. Fe2O3, CrO2, etc. or magnetic metallic powder such as Fe, Co, etc. to a warming treatment in an acid soln. contg. Sn<2+> to stick Sn<2+> on the surface, then washing thoroughly the magnetic powder is prepd. On the other hand, an aq. metallic salt soln. selected from Au, Ag, Pd, Rh, Pt and Cu which are non-magnetic metals having >=+0.15V oxidation-reduction potential is prepd. The Sn<+>-deposited magnetic powder put into such soln. and after the powder is subjected to a warming treatment, the powder is washed, filtered and dried to stick the non- magnetic film thereon at 0.1-2.0pts.wt. by 100pts.wt. the magnetic powder. The magnetic layer dispersed uniformly with such magnetic powder in the binder is formed on the substrate. The magnetic recording layer which does not require incorporation of an electrification-preventive agent such as carbon black therein, has the excellent electromagnetic convertion characteristic and prevents thoroughly electrification is thus obtd.
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