| 摘要 |
The present invention provides a magnetic recording medium wherein both of a reduction in the particle diameter of a ferromagnetic powder and an increase in the filling ratio of the powder in a magnetic layer are attained and the magnetic layer is excellent in surface smoothness and electromagnetic conversion property. A magnetic recording medium comprising at least a non-magnetic support, a lower non-magnetic layer on one surface of the non-magnetic support, and an upper magnetic layer on the lower non-magnetic layer, wherein the lower non-magnetic layer contains at least carbon black, a non-magnetic inorganic powder other than carbon black, and a binder resin, the upper magnetic layer contains at least a ferromagnetic powder and a binder resin containing a polar group, and the ferromagnetic powder is a ferromagnetic metal powder having an average major axis length of 10 to 50 nm, or a hexagonal ferrite magnetic powder having an average plate diameter of 5 to 40 nm, and the polar-group-containing binder resin is contained in the upper magnetic layer in such an amount that a proportion of said polar group to unit specific surface area based on the BET method of the ferromagnetic powder is set into a range of 0.18 to 0.35 mumol/m<SUP>2</SUP>.
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