MAGNETIC RECORDING MEDIUM AND ITS PRODUCTION

摘要

PURPOSE:To obtain a magnetic tape having a passive film which can suppress the increase of the coefft. of friction with lapse of time by subjecting a magnetic tape coil formed with a thin ferromagnetic metallic film layer essentially consisting of cobalt on a substrate to an oxidation treatment preferably under low humidity of 45% RH and at 40-90 deg.C. CONSTITUTION:The thin ferromagnetic metallic film layer 12 which contains 80wt% cobalt and 20wt% nickel on the surface of a base film 1 consisting of a PE terephthalate and is provided with an oxide film 14 on the surface of columnar particles 13 is taken out of a vacuum deposition vessel 3 and is subjected to the heating treatment for 3hr at 60 deg.C treatment temp. and under 30% relative humidity in the heat treatment vessel in which the atomospheric pressure is maintained. The treated film is cut to a prescribed width after the treatment to form the magnetic tape. The part where the passive film is formed in the magnetic table obtd. in the above-mentioned manner is within about 2cm from the transverse ends. The coefft. of friction is additionally decreased and the durability is additionally improved if a lubricating layer consisting of a fatty acid base org. or fluorine org. compd. if formed on such passive film.