Kao Corporation

Osamu Yoshida

Noriyuki Kitaori

Hirohide Mizunoya

Katsumi Sasaki

Junko Ishikawa

Akira Shiga

Katsumi Endo

Shigemi Wakabayashi

Yuzo Matsuo

Takashi Ishii

Takeshi Miyamura

Yutaka Sano

Katsumi Endoh

Kazuhiko Nakayama

Shingo Hashimoto

Katsumi Endho

A magnetic recording medium comprising a substrate having an uppermost magnetic layer containing ferromagnetic metal powder and a lower magnetic layer which is adjacent to the uppermost magnetic layer, wherein the uppermost magnetic layer has an average dry thickness of 0.03 to 0.5 .mu.m, the ferromagnetic metal powder in the uppermost magnetic layer is orientated in the horizontal direction of the magnetic recording medium, the magnetic recording medium has a coercive force of 120 kA/m or higher in the horizontal direction thereof, and a ratio of a maximum magnetic susceptibility .chi..sub.max with an external magnetic field applied in the direction perpendicular to the magnetic recording medium to a magnetic susceptibility .chi..sub.8 with an external magnetic field of 8 kA/m applied in the same direction, .chi..sub.max /.chi..sub.8, is 1.3 or higher.

Magnetic recording medium

The present invention is a magnetic recording medium comprising a substrate and a magnetic layer, wherein said magnetic layer is coated on said substrate, said magnetic layer is an Fe--N--O magnetic layer, each of Fe content F.sub.1, N content N.sub.1 and O content O.sub.1 contained in said Fe--N--O magnetic layer satisfies respective requirements F.sub.1 =50-80 at. %, N.sub.1 =9-25 at. %, O.sub.1 =11-36 at. % and N.sub.1 &lt;O.sub.1, and said magnetic layer exhibits a coercive force Hc in a horizontal direction ranging from 1200 to 2400 Oe. This magnetic recording medium exhibits excelleny C/N.

A magnetic recording medium comprising a substrate, a magnetic layer, a protective layer and a lubricant layer, wherein the magnetic layer is coated on the substrate, the protective layer is coated on the magnetic layer, the lubricant layer is coated on the protective layer, the magnetic layer is an Fe--C--O metal magnetic layer containing Fe, C and O, the protective layer is a diamond-like carbon layer and the lubricant is a fluorine-contained lubricant. The magnetic recording medium using an inexpensive Fe as a magnetic material, has excellent electromagnetic conversion characteristic, durability, corrosion resistance and running capability.

A magnetic recording medium comprising a substrate and a magnetic layer, wherein the magnetic layer is an Fe--N--O magnetic layer, and a distribution of N density in a depth direction of said Fe--N--O magnetic layer has a maximum value N1 in an intermediate layer section of said Fe--N--O magnetic layer, and the maximum value N1 ranges from 20 to 50 at. %, and an area where a density value is equal to or more than half of said maximum value N1 ranges from 100 to 500 .ANG. in a depth direction of said Fe--N--O magnetic layer. The magnetic recording medium has an excellent C/N.

A magnetic recording medium comprising a substrate and a magnetic layer, wherein the magnetic layer is coated on the substrate, the magnetic layer is an Fe--C--O magnetic layer and has a oblique column structure, and an O concentration (at. %) Oc in a center part of the column and an O concentration (at. %) Os around a surface part of the column satisfy Oc&lt;Os. The magnetic recording medium has an excellent S/N, and has excellent corrosion resistance and durability.

The present invention is a magnetic recording medium comprising a substrate and a magnetic layer including a binder resin and a plate-like magnetic powder of which easy axis of magnetization exists in a plane, and this magnetic recording medium is excellent in recording and regeneration characteristics.

A system for magnetic contact duplication by transferring an information signal recorded on a mother tape onto a blank tape, wherein the mother tape and the blank tape each includes at least one magnetic thin film having columns of magnetic grains grown obliquely, the column gradient .theta..sub.B1 of the magnetic grains in an uppermost magnetic thin film of the blank tape being smaller than the column gradient .theta..sub.M1 of the magnetic grains in an uppermost magnetic thin film of the mother tape, the mother tape and blank tape are superposed such that the column growth direction of the magnetic grains in the uppermost magnetic thin film of the mother tape and the column growth direction of the magnetic grains in the uppermost magnetic thin film of the blank tape intersect and such that these uppermost magnetic films face each other, and a bias magnetic field is applied from the substrate side of the blank tape.

System for magnetic contact duplication

A magnetic recording medium is disclosed which comprises a support having thereon a thin magnetic metal film comprising columns of magnetic metal grains grown obliquely, wherein each of said columns is bent having a curvature rate of 10% or more.

In order to improve a corrosion resistance and a running stability of a magnetic recording medium having a protective layer comprising a diamond-like carbon thin film and reduce cupping, the protective layer formed on the magnetic layer is composed of the diamond-like carbon thin film containing a material which fluoresces.

Magnetic recording medium having a protective carbon film which contains

A metal deposition magnetic recording medium comprising a support and at least one magnetic layer formed thereon by deposition, said recording medium having a residual magnetic flux density and a coercive force which satisfy the relationships of (1) and (2): ##EQU1## Br: Residual magnetic flux density H.sub.CV : Coercive force in the vertical direction

A metal film type magnetic recording medium in which the saturated magnetic flux density is high and iron having a good corrosion resistance is applied. The magnetic layer comprises metal films formed, in order on a base film, each containing iron, cobalt and nickel as main components.

Magnetic recording medium comprising successive magnetic metallic films

A magnetic recording medium is disclosed which comprises a support and formed thereover a magnetic layer having a multilayer structure comprising at least two vapor-deposited metal films each made up of columns, each vapor-deposited metal film having a degree of column curvature of 20% or lower, and any of said vapor-deposited metal films which is closer to said support having a higher degree of column curvature than any of said vapor-deposited metal films which is closer to the surface. The magnetic recording medium enables high-density recording, is excellent especially in output characteristics and C/N characteristics, and has a balance between longitudinal-direction magnetic characteristics and vertical-direction magnetic characteristics.

The present invention is directed to methods and apparatus for preparing a magnetic recording medium having a nonmagnetic substrate layer, a back-coat layer containing a metal or semi-metal which has been deposited in a vacuum on one surface of the substrate, a magnetic layer which has been deposited in a vacuum on the other surface of the substrate, and an optional top-coat layer which has been sprayed in a vacuum onto the magnetic layer. A quantity of oxygen is introduced during depositing of the back-coat layer to obtain a surface resistance of 5 to 10.sup.5 ohms.

Magnetic recording medium manufacturing method and manufacturing

A magnetic recording medium which is uncostly, can dispense with environmental pollution control measures unlike the case of Co or Cr, is highly durable, permits high density recording and comprises a magnetic film selected from the group consisting of:

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Tochigi, Japan

Osamu Yoshida