JPH0736218B2 - Magnetic recording medium - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium having a ferromagnetic metal thin film suitable for high density magnetic recording as a magnetic recording layer.

2. Description of the Related Art Conventionally, what has been widely put to practical use as a magnetic recording layer is γ-Fe ₂ O ₃ , Co-doped γ-Fe ₂ O ₃ , CrO ₂ , or a ferromagnetic metal or alloy fine powder such as iron. Magnetic material is vinyl chloride,
It is a coating type magnetic layer which is dispersed in an organic binder such as a vinyl acetate copolymer, a styrene-butadiene copolymer and an epoxy resin and then coated and dried on a substrate such as a polymer film.
The so-called metal thin film magnetic recording medium using a ferromagnetic metal thin film layer as a magnetic recording layer, which is expected to give an excellent signal-to-noise ratio (S / N) in the high density region with the increasing demand for high density recording in recent years Has been attracting attention and efforts are being made toward its practical application (for example, the foreign journal “IEE Transactions on Magnetics” (IEEE TRANSA
CTIONS ON MAGNETICS Vol.MAG-20, No.5,669-674
(1984))].

The main object of the improvement of such a magnetic recording medium is to improve the durability of the magnetic recording layer while maintaining excellent electromagnetic conversion characteristics.

Therefore, many proposals have been made regarding this, and a protective film is formed on a ferromagnetic metal thin film such as a Co-P, Co-Ni-O, or Co-Cr film that is generally used as a magnetic recording layer, and a magnetic head or a traveling system is formed. To reduce friction with mechanical materials of
No. 52-153707, Japanese Patent Laid-Open No. 59-171026], or by providing fine irregularities on a polymer film and providing a ferromagnetic metal thin film on the surface, the true contact area is reduced, and the scratch resistance is improved. It has been proposed to improve the running performance of the vehicle (for example, JP-A-56-10455 and JP-A-59-121631).

Problems to be Solved by the Invention However, in the above-mentioned configuration, when the magnetic head is alloyed, it has a problem that a good S / N can be maintained only in a specific environment and the practical range is restricted. It was

In view of the above problems, the present invention provides a magnetic recording medium that is not particularly limited in its practical range by disposing a protective film that is durable even under friction with an alloy head.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording medium of the present invention comprises a magnetic recording layer made of a ferromagnetic metal thin film in which a plasma polymerized film is arranged on the surface layer of magnetic fine particles having a columnar structure. Be prepared.

Action The present invention has the above-described structure, in which the plasma-polymerized film is formed as a part of the columnar magnetic fine particles constituting the thin film, unlike the conventional structure in which the plasma-polymerized film is laminated on the ferromagnetic metal thin film. As a result, sufficient durability is ensured even with friction with the alloy head.

EXAMPLES Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention. In FIG. 1, 1 is a polyethylene naphthalate film having a thickness of 10 μm, 2 is a ferromagnetic metal thin film, which is composed of columnar fine particles 3 and a plasma polymerized film 4 arranged on the surface layer portion.

The feature of the present invention is that the plasma-polymerized film 4 in the surface layer portion is formed integrally with the columnar fine particles, and as can be understood from the manufacturing method described later, the plasma-polymerized film 4 contains ferromagnetic metal thin film constituent elements. It is considered that it is closely related to the fact that it also has excellent durability. The atomic ratio of the constituent elements of the ferromagnetic metal thin film contained in the plasma polymerized film is preferably 3 to 10%. If it is 3% or less, the effect of improving the durability due to the increase in hardness is weak, and if it is 10% or more, the flexibility is lost and the durability is lowered.

In this embodiment, the columnar fine particles are those that extend almost vertically and
Perpendicular magnetization film made of -Cr (Cr is 20.5 wt%) with a film thickness of 1650
Å, the plasma polymerized film 4 was the surface layer portion (100 to 150 Å), and the monomer used was octafluorocyclobutane.

FIG. 2 is a schematic diagram of the internal structure of a vapor deposition apparatus used to obtain the magnetic recording medium having the structure shown in FIG.

In FIG. 2, 5 is a polymer film, 6 is a delivery shaft, 7 is a take-up shaft, 8 is a cylindrical can, 9 is an evaporation part, and 10
Limitation vapor stream consists incident angle component in the range of l ₁ at a position along the cylindrical can of l _2, l ₁ is the crystal growth early, l ₂ parts corresponds to the final portion. 11 is a mask and 12 is a slit part. 13 is a monomer introduction nozzle and 14 is a discharge electrode. 15
Is a vacuum container, and 16 is an evacuation system.

The monomer introduction nozzle consists of a copper pipe with a diameter of 10 mm and 50 pores with a diameter of 0.2φ arranged at a pitch of 12 mm. The discharge electrodes are a pair of aluminum rods with a diameter of 15 mm, which are separated by 22 mm, and between the two electrodes. AC100KHz is applied to generate glow discharge to partially ionize and polymerize the monomer. The arrangement is such that the monomer vapor is aimed at approximately l ₂ .

Using this equipment, we find conditions that the thickness of the surface layer is in the range of 100Å to 150Å, and change the monomer to produce tape.

In order to improve the running property as a tape, each tape was comparatively examined by adding a lubricant layer in which about 50% Å vapor-deposited perfluorodecanoic acid was deposited by a vacuum deposition method.

In each of the comparative examples, a Co-Cr perpendicularly magnetized film was formed, a plasma polymerized film was formed as in the conventional case, and perfluorodecanoic acid was vacuum-deposited on the plasma polymerized film.

For vertical vapor deposition of Co-Cr, a cylindrical can temperature was kept at 165 ° C, a vertical coercive force of 720 (Oe) was used, and a magnetic head was a sendust head with a gap length of 0.2 (μm).

The S / N change is recorded and reproduced repeatedly in each environment,
In the reproduction S / N at the time of the second recording / reproduction, the initial value was set to O (dB) for relative comparison.

As is clear from the above table, the configuration of the present invention has almost no difference due to the environment, and the S / N reduction is almost negligible. It has no practical use in the recording and playback operations of, and is highly dependent on the environment.

Although the polymer film is polyethylene naphthalate in the examples of the present invention, it may be polyethylene terephthalate, polypropylene, oriphenylene sulfide, polyamide, polyimide or the like.

As the ferromagnetic metal thin film, in addition to the Co-Cr perpendicular magnetization film, Co-Cr
Perpendicular magnetic film such as Ti, Co-Ta, Co-Mo, Co-W, Co-Cr-Nb, C
It may be an oblique vapor deposition film of o-O, Co-Ni, Co-Fe, Co-Sn, Co-Mg, Co-Ni-O or the like.

The monomer used for forming the plasma-polymerized layer may be tetrafluoroethylene, hexafluoroethane, ethylene, butylene, hexafluoropropylene, difluoroethane, trifluoromethane, xylene or the like.

EFFECTS OF THE INVENTION According to the magnetic recording medium of the present invention, in combination with an alloy head, it is possible to obtain an excellent effect that a stable S / N can be obtained even after repeated recording / reproduction in various practical use environments. You can

[Brief description of drawings]

FIG. 1 is a partially enlarged cross-sectional view of a magnetic recording medium in one embodiment of the present invention, and FIG. 2 is a schematic internal configuration diagram of a vapor deposition apparatus used to obtain the magnetic recording medium of the present invention. 1,5 ... Polymer film, 3 ... Columnar fine particles, 4 ... Plasma polymerization layer, 9 ... Evaporation source, 13 ... Monomer introducing nozzle, 14 ... Discharge electrode.

Claims (1)

[Claims] 1. A magnetic recording medium comprising a magnetic recording layer composed of a ferromagnetic metal thin film integrally formed as a plasma-polymerized film containing a ferromagnetic metal thin film constituent element in a surface portion of a magnetic fine particle having a columnar structure. .