MAGNETIC RECORDING MEDIUM

摘要

PURPOSE:To decrease the variance of the performance of a magnetic recording medium contg. magnetic powder and to improve the dwell stability during the dispersion stage by specifying the ratio of the carbon and iron existing in the surface region of the magnetic powder. CONSTITUTION:The ratio of the carbon and iron (carbon/iron) existing in the surface layer of the magnetic powder of the magnetic recording medium contg. the magnetic powder is specified to <=.06 by weight. The magnetic powder is exemplified by various ferromagnetic powders including iron oxide magnetic powders such as gamma-Fe2O3, Co-contg. gamma-Fe2O3, Fe2O4 and Co-contg. Fe2O4, among which the Co-contg. iron oxide and metallic magnetic powder are more preferably. The preferred BET value of the magnetic powder is >=30m<2>/g. At least a polyurethane is usable as the binder for the magnetic layer and can be synthesized by the reaction of a polyol and polyisocyanate. The electromagnetic conversion characteristic of the medium is thereby improved and the dwell stability of the magnetic paint during the dispersion of the magnetic powder is improved.