| 摘要 |
PURPOSE:To obtain excellent durability and electromagnetic conversion characteristic by using a heat-resistant base film which is limited in the width of the height distribution of fine productions on the surface for a perpendicular magnetic recording medium consisting of Co base such as Co-Cr alloy. CONSTITUTION:A polyimide film of 9mum thickness consisting of an acid dianhydride component and SiO2 particles having 450A average grain size is formed. And a perpendicularly magnetized film consisting of 79wt.% Co and 21wt.% Cr is deposited by evaporation to 0.4mum thereon, by which the film is formed. A Co oxide film is sputtered to 120Angstrom as a protective layer on said film and a back coating layer of about 0.5mum incorporated with carbon particles in a polyester binder is formed on the rear face. The fine projections on the film surface at this time are 10<5>-10<8> pieces per mm<2> in average and the height distribution of said projections is specified to H0.1<600Angstrom , H1>120Angstrom , H10>100Angstrom and is determined to satisfy (H1-H10)<200Angstrom when the projection heights corresponding to 0.1%, 1% and 10% in order of the larger heights are designated as H0.1, H1, H10. The recording medium having the excellent durability and electromagnetic conversion characteristic is thereby obtd.
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