Hitachi Maxell, Limited

Hiroshi Zaitsu

Takato Karashima

Sadao Yamashita

Osamu Saito

Kunio Mizushima

Fumio Togawa

Jozo Shimizu

Shigeyuki Hosoo

Takashi Yamase

A magnetic recording medium having two magnetic layers, which comprises an upper magnetic layer and a lower magnetic layer, said lower magnetic layer having a coercive force of at least 100 oersteds, preferably 100 to 500 oersteds, lower than that of the upper magnetic layer, the thickness of the upper and lower magnetic layers being in the ratio of the thickness of the upper magnetic layer to that of the lower magnetic layer of 1/1 to 1/9, and the total coercive force of the upper and lower magnetic layers being 1,000 oersteds or more. The magnetic recording medium has excellent sensitivity and frequency characteristics at low and high frequency bands with less noise.

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.

A magnetic recording medium which comprises a base material and a magnetic layer provided on its surface, said magnetic layer comprising metallic magnetic particles, a binder and a salt of lanolin fatty acid wherein the oxidation resistance of the metallic magnetic particles is highly improved and the metallic magnetic particles are in a good dispersion state so that the magnetic recording medium shows an increased maximum magnetic flux density is disclosed.

Magnetic recording medium comprising a support or carrier sheet and a magnetic layer formed on one side of the support, wherein there is provided between the support and the magnetic layer at least one intermediate layer of resinous polymeric material including particles of carbon black having large specific surface area and high oil absorption so that electrification of the recording medium can be prevented with good adhesiveness of the magnetic layer to the support.

A magnetic recording medium improved in durability which comprises a substrate and a magnetic layer of about 1.0 to 10.mu. in thickness comprising magnetic particles and a binder and being formed on the substrate, characterized in that the magnetic layer further comprises (a) a liquid hydrocarbon having a melting or flowing point of about -20.degree. to -60.degree. C. with (b) .alpha.-iron oxide particles having a particle size of 0.5 to 2.mu. and/or (c) a higher fatty acid having a melting point of about 45.degree. C. or higher.

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Takatsuki, Japan

Hiroshi Zaitsu