Hitachi Maxell, Limited

Akira Morioka

Yoshiyuki Takahira

Takeshi Matsuura

A magnetic recording medium having high running stability and good magnetic characteristics without causing an abrasion problem, which comprises a base film, a magnetic layer provided on one surface (i.e. the major surface) of the base film and a back coat layer provided on the other surface (i.e. the back surface) of the base film, the back coat layer comprising a binder and non-magnetic particles dispersed therein, characterized in that the non-magnetic particles comprise at least one soft inorganic pigment having a hardness of less than 5 in Mohs' scale of hardness and at least one hard inorganic pigment of not less than 5 in Mohs' scale of hardness and of not more than 0.2 .mu.m in average particle size in a weight ratio of the soft pigment to the hard pigment of 99:1 to 50:50.

Magnetic recording medium

Magnetic recording medium having a magnetic layer in which magnetic powder of the magnetic layer includes iron oxide magnetic powder with more than 30 m.sup.2 /g specific surface area measured by BET method, chromium dioxide (CrO.sub.2) magnetic powder with more than 30 m.sup.2 /g specific surface area measured by BET method, and the rate of the chromium dioxide powder is within a range more than 3% to less than 20% by weight in the total amount of the magnetic powder in the magnetic powder. Said magnetic layer further includes carbon black.

A magnetic recording medium having a high durability with good electro-magnetic properties, which comprises a base material and a magnetic layer provided thereon, the magnetic layer containing magnetic particles and a binder, characterized in that the magnetic layer further comprises alpha-Fe.sub.2 O.sub.3 particles, Al.sub.2 O.sub.3 particles and Cr.sub.2 O.sub.3 particles.

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Kyoto, Japan

Akira Morioka