Hitachi Maxell, Limited

Fumio Togawa

Shigeo Aoyama

Kenji Sumiya

Osamu Saito

Haruo Andoh

Hiroshi Zaitsu

Takato Karashima

Toshihiko Tanabe

A magnetic recording medium comprising a substrate, a magnetic layer formed on the substrate and comprising a metallic magnetic material as a recording element and a protective layer formed on the magnetic layer and comprising a perfluroalkyl polyether derivative having a phosphate terminal group, which has improved durability and corrosion resistivity.

Magnetic recording medium

A magnetic recording medium suitable for high-density recording which comprises a substrate and a magnetic layer thereon, the magnetic layer containing acicular magnetic metal particles having a particle size of not more than 0.3.mu. and a squareness ratio in the vertical direction of the layer being not less than 0.4.

An improved magnetic recording medium suitable for high density recording is disclosed, which has a squareness ratio in the vertical direction of 0.6 or more and an orientation ratio (squareness ratio in the vertical direction/squareness ratio in the lengthwise direction) of 0.7 or more, prepared from acicular magnetic iron oxide particles having crystalline magnetic anisotropy and a ratio of Fe.sup.2+ /Fe.sup.3+ of 0.05 or less uniformly cobalt-doped, the particles having preferably a particle size of 0.3.mu. or less and an axial ratio of 6 to 10.

A magnetic recording medium suitable for high-density recording, which comprises a magnetic layer containing uniaxial anisotropic, acicular iron oxide particles having a particle size of not more than 0.3.mu., with a surface layer containing a major amount of cobalt being formed on seeds of the magnetic particles, said magnetic recording medium having a residual magnetic flux density both in a vertical direction and in a horizontal or longitudinal direction of not less than 1000 gauss.

A magnetic recording medium which comprises a base and a magnetic layer of a magnetic coating composition comprising magnetic particles and a binder provided on said base, characterized in that the magnetic coating composition further comprises a dialkylsulfosuccinate.

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Ohtsu, Japan

Fumio Togawa