JPH0675284B2 - Magnetic recording medium - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium, and more particularly to a so-called metal thin film type magnetic recording medium in which a magnetic recording layer made of a ferromagnetic metal is arranged on a polymer film.

Description of the Related Art Conventionally, what is subjected to widely used as a magnetic recording _{layer, γ-Fe 2 O 3,} Co -doped _{γ-Fe 2 O 3, CrO} 2, or ferromagnetic alloy fine powder magnetic such as Fe This is a coating type magnetic layer in which a material is dispersed in an organic binder such as a vinyl chloride-vinyl acetate copolymer, a styrene butanediene copolymer, an epoxy resin or the like, coated on a substrate such as a polymer film and dried. With the increasing demand for high-density recording in recent years, a metal thin film type using a ferromagnetic metal thin film formed by sputtering, ion plating, wet plating, electron beam evaporation, etc. as a magnetic recording layer has attracted attention, and efforts have been made toward its practical application. Has been done in various ways. However, these have the drawback that the magnetic recording layer is peeled off or damaged due to contact with the head during running, as compared with the conventional coating type.

FIG. 2 is an enlarged sectional view of a conventional magnetic recording medium.

In FIG. 2, 1 is a polymer film such as polyethylene terephthalate, 2 is an obliquely evaporated film made of, for example, Co—Ni—O, and 3 is a protective film.

It is considered that the protective film of No. 3 makes efforts to suppress the destruction phenomenon occurring in the magnetic recording layer, and many proposals have been made.

For example, JP-A-52-153707, JP-A-53-88704, JP-A-5
9-171026] Problems to be Solved by the Invention However, in the configuration as shown in FIG. 2, when the magnetic head used shifts from ferrite to alloy head and the environmental conditions used become wide, Electric noise is randomly generated, the signal-to-noise ratio is momentarily lowered, and there is a problem that reliability in high density magnetic recording is lost.

In view of the above problems, the present invention provides a magnetic recording medium having a ferromagnetic metal thin film with improved reliability.

Means for Solving the Problems In order to solve the above problems, the magnetic recording medium of the present invention has a ferromagnetic film on the surface of the polymer film having a surface with different roughness formed of fine particles and having a smaller roughness. It arranged thin film, in which comprises a structure arranged two layers of SiO _{x (x} = 1.2~1.7) and lubricant layer on the other surface.

Effect According to the present invention, the electric charge generated on the surface which does not come into sliding contact with the magnetic head is appropriately and stably discharged by the SiO _x semiconducting layer, so that electrostatic noise due to abnormal discharge is not induced. Therefore, the signal-to-noise ratio (denoted as S / N) will be reduced in a pulsed manner, and the frictional charge can be reduced by the action of the lubricant, so a superior S / N can be stably obtained with a synergistic effect. The signal error rate in high density magnetic recording can be made extremely small and the reliability is improved.

EXAMPLES Hereinafter, magnetic recording media according to examples of the present invention will be described with reference to the drawings.

FIG. 1 is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention.

In FIG. 1, 4 is a polymer film formed of fine particles and having two surfaces with different surface roughnesses, which has a thickness of 12 μm, and is composed of intrinsic particles consisting of a polymerization residue in polyethylene terephthalate or silica added from the outside. Inactive particles are obtained by the co-extrusion method, and the surface roughness is 0.003μ as the average roughness (Ra) measured by a stylus type roughness meter.
m and 0.029 μm. The 0.003 μm surface is tentatively called the A surface, and the 0.029 μm surface is called the B surface.

High frequency glow discharge induced by applying high frequency electric field of 13.56MHz to A surface in argon atmosphere of 0.04 Torr, Co-Cr (Cr: 20.3wt%) was obliquely deposited, and thickness was 0.16μ.
m, a coercive force of 1460 (Oe), and a ferromagnetic metal thin film 5 having a squareness ratio of 0.89.

A SiO _x film 6 was arranged on the B surface by a high frequency sputtering method.

High frequency with 13.56 MHz, and a silicon purity 4 Nine to target, Ar and a mixed gas of O ₂ from the mixing ratio 1:10 Ar and O ₂ 1: 1 to, Ar and O ₂ of the total pressure To 0.1 Torr
To 0.01 Torr to form a SiO _x film of 0.25 μm.

Here, x is appropriately in the range of 1.2 to 1.7 from the viewpoint of both hardness and semiconducting property.

On this, vacuum-deposited stearic acid as a lubricant, about 40
The lubricant layer 7 of Å was arranged.

This was slit into a width of 8 mm, and the cumulative time of pulse-like S / N lowering during PCM recording and playback was measured. A commercially available alloy coated tape (MP tape) for 8 mm video was used as a comparative tape.

The length of the tape used is 90 minutes, and for 90 minutes, S / N
Is shown as the cumulative time when the value drops by 6 dB or more.

The recording bit length is 0.35 μm and the track pitch is 16 μm.

As described above, according to the present embodiment, the ferromagnetic metal thin film is arranged on the surface of the polymer film having the surface of different roughness formed of the fine particles, which has a small roughness, and the other surface is covered with SiO _x (x =
1.2 to 1.7) layer and lubricant layer are arranged, so that S / N based on noise due to static electricity that frequently occurs especially in low humidity environment
The pulse-like decrease of P can be maintained at a level that does not cause any problem even in PCM recording / reproduction, and the characteristics of high S / N in high-density magnetic recording / reproduction of ferromagnetic metal thin film can be fully utilized.

In this example, the polymer film was polyethylene terephthalate, but polyamide, polysulfone,
Polyphenylene sulfide, polycarbonate, polyimide, etc. may be used, and the roughness of A side is from 0.001 μm in Ra.
0.01 μm, and the B surface roughness may be Ra from 0.02 to 0.2 μm.

Although the ferromagnetic metal thin film is a Co—Cr oblique vapor deposition film, it may be a vertical vapor deposition film, a vertical sputtering film, or a stack with a soft magnetic layer.

Also, as the material, Co-Fe, Co-Ni, Co-Ti, Co-O, Co-Mg, Co-
V, Co-W, Co-Ta, Co-Mo, Co-Ni-Cr, Co-Ni-O, etc. may be used.

Although the SiO _x thin film was formed by the high frequency sputtering method, it may be formed by the reactive vapor deposition method, and the film thickness may be 0.15 μm to 1.0 μm.

Stearic acid was used as a lubricant and was formed by a vacuum deposition method, but was formed by a solution coating method, a glow polymerization method, or the like.
Any of fatty acids, fatty acid esters, fatty acid amides, fluoroalcohols, hydrocarbon polymer films, etc. may be used.

EFFECTS OF THE INVENTION As described above, according to this embodiment, excellent effects such as obtaining a high-density magnetic recording medium without a pulse-like S / N reduction due to static electricity can be obtained.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a conventional magnetic recording medium. 4 ... Polymer film, 5 ... Ferromagnetic metal thin film, 6 ...
SiO _x layer, 7 ... Lubricant layer.

Claims (1)

[Claims] 1. A polymer film formed of fine particles having a surface with different roughness, a ferromagnetic metal thin film is arranged on a surface having a small roughness, and a SiOx layer (x = 1.2 to 1.7) is formed on the other surface. A magnetic recording medium comprising two layers of a lubricant layer.