JPH02108219A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain such a medium that has durability against repetitive high-density digital recording by providing a first ferromagnetic metal film by oblique vapor deposition on a polymer film, dispersing numbers of resin particles at certain intervals thereon, and further vapor depositing second and third ferromagnetic metal films in such a manner that the deposition angles for the second and third films are almost symmetric each other to the normal of the film. CONSTITUTION:The first ferromagnetic film 6 is formed by oblique vapor deposition with the min, incident angle of 40 degrees and the oxygen partial pressure of 6 X10-<5> Torr to result in a Co-Ni film about 550 Angstrom thick, contg. 80wt.% Co content, on a polymer film 5 such as polyethylene terephthalate, 10mum thick, 30 Angstrom mean surface roughness and 60 Angstrom max. roughness. Then 150-Angstrom diameter polyimide particles 7 are dispersed on the film by distribution of 2 X 10<9>/cm. The second and third ferromagnetic metal films 8 and 9 having the same Co-Ni compsn, as the thin film 6 are then formed by oblique vapor deposition on the film 6 including the particles with the min. incident angle of 45 degrees and the oxygen partial pressure of 5 X 10-<5> Torr. The angles of deposition for two layers are symmetric each other. At last, the magnetic tape is obtained by applying hexaphenyl cyclotrisilazane on the top surface, while perfluoro arachic acid on the back surface.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording medium whose magnetic recording layer is a ferromagnetic metal thin film suitable for high-density magnetic recording.

Conventional technology Recent advances in recording technology have significantly improved the recording density not only per unit area but also per unit volume. There is a strong desire for the practical application of vapor-deposited tapes and the like as magnetic recording layers. Therefore, the importance of research on tribology to deepen understanding of friction, wear, etc. that occurs at sliding interfaces has recently been recognized, and development is progressing in various fields [Television, 7 Academic Journals Vo440. A6. (1986) 472
page〕. FIG. 2 is an enlarged sectional view of a conventional magnetic recording medium. In Fig. 2, reference numeral 1 indicates a polymer film made of polyethylene terephthalate, polyimide, etc., to which a finely divided surface is applied if necessary [JP-A-159-20742
No. 2 and JP-A-69-121631 are used. 2 is C.

-Ni-0 obliquely deposited film, Co-Cr, Go-Cr-Nb
A magnetic recording layer such as a perpendicular magnetization film, etc., 3 is a protective layer, 4 is a single layer of squared black, and a resin layer containing particles such as carbon powder, calcium carbide powder, etc. is used as a protective layer mainly to improve running properties. It is often provided when this alone is not sufficient.

Conventionally, the protective layer has been improved in wear resistance by a vapor-deposited film of a fatty acid metal salt disclosed in JP-A-54-113303;
Known examples include the sputtered film of a polymer having imide groups disclosed in JP-A-57-116771, and an example using a diamond-like hard carbon film (Japan Society of Applied Magnetics, 46th Research Meeting Materials). . Also, as a layer for lubricating purposes, vapor deposition method.

Many attempts have been made to coat fatty acids, fatty acid amides, etc. by wet coating methods (for example, Japanese Patent Publication No. 56-30609). However, in the above example, it is not possible to fully cope with the expansion of usage environmental conditions and the sophistication of practical requirements for alloy-based magnetic heads, so improvements are being considered by combining fluorocarbons on the adsorption layer of fatty acid metal salts. system with a lubricating layer (Japanese Unexamined Patent Publication No. 1986-12)
0331 publication), a fluorine-containing lubricating oil layer arranged on a hard carbon layer (fF Publication No. 126827/1983), and a lubricant layer formed on a 5t-N-0 thin film (Japanese Patent Publication No. 81-131231), etc.

Problems to be Solved by the Invention However, when digital recording is performed at higher density using a magnetic recording medium having the above-mentioned configuration, there is a problem that the error rate increases and it is not possible to obtain a sufficiently large recording density for practical use. Improvement was desired. The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a magnetic recording medium with improved error rate in high-density digital recording.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording medium of the present invention comprises:
A first ferromagnetic metal thin film is placed on the polymer film by oblique vapor deposition, resin particles are placed on top of the first ferromagnetic metal thin film, and a second ferromagnetic metal thin film is placed on the polymer film. The third ferromagnetic metal thin film is constructed so that the deposition direction is almost symmetrical with respect to the perpendicular line.

Effect The magnetic recording medium of the present invention has the above-described structure, and the protrusions of the ferromagnetic metal thin film formed by the resin particles are formed directly above the grains, so that the magnetic recording medium can be made strong against stress. Being sandwiched between magnetic thin films makes it resistant to deformation, and resin particles can also improve durability, and unlike when the particles are inorganic fine particles, they do not cause local damage to the ferromagnetic metal thin film. ．． The third ferromagnetic metal thin film cancels out the anisotropy in the growth direction and minimizes the amount of peak shift, making it possible to improve the error rate in high-density digital recording.

Embodiment Hereinafter, an embodiment 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 Figure 1, 5 is a polymer film such as polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyether ether ketone, polyamide, polyimide, etc., and 6 is Co, G.
o-Ni, Co-Ti, Go-Cr,
Go-W, Co-0, Go-Ni-0, C
.

The first ferromagnetic metal thin film, such as -Cr-Nb, is formed by an oblique evaporation method, and the film thickness is preferably in the range of 300 to 1000. 7 is polyester, polycretane, polyethylene, polyamide, polyimide.

It is preferable to use resin particles such as polysulfone, polyethersulfone, polycarbonate, polystyrene, polyacrylate, polyvinyl butyral, polyphenylene oxide, and phenoxy resin, and to have a height ranging from 60 to 260 people.

If it is less than 60 Å, the durability will be poor, and if it is more than 250 people, the electromagnetic conversion characteristics will be unfavorable due to spacing loss. 8 and 9 are Co-Ni, Co-0, and C.

-N i -0, Co -Or-Nb, etc. are selected from the same group as the first ferromagnetic metal thin film, and 8 and 9 are the second ferromagnetic metal thin films whose direction of oblique deposition is approximately symmetrical with respect to the perpendicular to the film surface. The thicknesses of the three ferromagnetic metal thin films are preferably the same, or even if adjusted, the difference is preferably about 10 to 30%.

1o is a protective lubricant layer, which is a plasma polymerized film and a carbon film.

It is a combination of a protective film such as S102 film and a lubricant such as fatty acid or fatty acid amide, and is configured within a thickness range that does not significantly affect spacing loss.

Reference numeral 11 denotes a back coat layer, which is a coating layer of 0.3 μm to 1 μm containing resin, filler, and if necessary, lubricant.

Examples of the present invention will be described in more detail below in comparison with comparative examples.

[Example-1] A cylindrical can with a diameter of 1 m is placed on a polyethylene terephthalate film having a thickness of 10 μm, an average roughness of 30 people, and a maximum roughness of 6o, a minimum incident angle of 40 degrees, and an oxygen partial pressure of el
Co-Ni (Co: 8) at 10 (Torr)
0 wt %) was deposited by electron beam evaporation by 650 people, and 2×109 polyimide spheres with a diameter of 160 people were placed thereon.
On top of that, the minimum angle of incidence is 45 degrees, the oxygen partial pressure is 6x 1o (
Torr) and Go-Ni (Co: 80 wt%
) was then electron beam evaporated on 600 people, and without being re-wound, it was moved from the winding axis to the unwinding axis, and the same electron beam evaporation was performed on 600 people with the incident direction reversed. 80 people made a plasma polymerized film using silazane as a monomer and 60 people made a perfluoroarachidic acid film by vacuum evaporation, and the back coat layer was 0.4 μm thick.
The magnetic tape was arranged 8 mm wide.

[Example-2] A flat elliptical sphere (polymethyl methacrylate sphere) with a height of 100 people and a long axis of 900 people was placed in place of the polyimide sphere of Example-1, and the other parts were I made a prototype of 8mm tape with the same configuration.

[Comparative Example-1] In Example-1, the second. An 8 mm tape having the same structure was produced as a prototype except that the third ferromagnetic metal thin film was deposited in the same direction as the first.

[Comparative Example 2] An 8 mm tape having the same configuration as in Example 1 except that the fine particles were replaced with Zr02 balls with a diameter of 150 people was manufactured.

These tapes were modified into 8mm video tapes and recorded and reproduced repeatedly at a track pitch of 10 μm and a linear recording density of 135 KBPI, and the error rates were compared. The results are shown in the table below.

Effects of the Invention As described above, the present invention has the excellent effect of providing an excellent magnetic recording medium that can withstand repeated high-density digital recording.

[Brief explanation of the drawing]

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. 5... Polymer film, 6... First ferromagnetic metal thin film, 7... Resin fine particles, 8...
second ferromagnetic metal thin film, 9... third ferromagnetic metal thin film;

Claims (1)

[Claims] A magnetic recording medium having a magnetic recording layer in which a first ferromagnetic metal thin film is disposed on a polymer film by oblique vapor deposition, resin particles are disposed thereon, and second and third ferromagnetic metal thin films are disposed thereon. , a magnetic recording medium characterized in that the deposition directions of the second and third ferromagnetic metal thin films are substantially symmetrical with respect to a perpendicular line.