JP2953138B2 - Manufacturing method of magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

^2. Description of the Related Art In recent years, the density of magnetic recording has been remarkably increasing, and recording / reproduction at 1 bit 1 μ ² is expected, and magnetic recording media using a ferromagnetic metal thin film as a magnetic recording layer have been actively developed. Such a magnetic recording medium is composed of Co-O, Co-
It is a tape-shaped or disk-shaped one in which a ferromagnetic metal thin film such as Ni-O or Co-Cr is provided, and a protective lubricating layer and a back coat layer are provided as necessary.

Hereinafter, a conventional method for manufacturing a magnetic recording medium will be described. FIG. 2 is a main part configuration diagram of a vacuum evaporation apparatus used for manufacturing a conventional magnetic recording medium. In FIG. 2, 1 is a polymer film, 2 is a cooling can, 3 is a feed shaft, 4 is a winding shaft, 5 is an evaporation source, 6 is a mask,
7 is a gas introduction port.

The operation of the vacuum evaporation apparatus configured as described above will be described below. For example, thickness 1
While moving along a cooling can 2 having a diameter of 1 m, a film 1 made of polyethylene terephthalate in which SiO ₂ microparticles having a diameter of 15 μm and having a diameter of 15 nm are dispersed and applied is moved while introducing oxygen gas from a gas introduction port. -Ni (Ni: 20 wt%) is electron beam deposited. The deposition starts with the vapor stream component near the tangent and the mask 6
Is performed by oblique vapor deposition in the range of the minimum incident angle limited by, for example, 35 degrees. By introducing oxygen gas, columnar fine particles formed by oblique deposition are refined,
The oxide layer on the surface of the columnar fine particles weakens the magnetic coupling between the particles and improves the noise, but in order to further improve the noise, the vapor deposition is performed once, for example, at 800 °, and the deposition is repeated twice to obtain a total of 1600 °. Is done. By doing so, 1
1 to 2 (dB) C / N than when 1600 ° is deposited
Can be improved.

[0005]

However, the above-mentioned conventional structure has a problem that the oxide layer between the first layer and the second layer becomes thick, and the short wavelength C / N is not sufficiently improved. Was.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method capable of mass-producing a magnetic recording medium with improved C / N at a short wavelength.

[0007]

In order to achieve the above object, a method for manufacturing a magnetic recording medium according to the present invention is characterized in that when depositing two layers on a polymer film moving along an endless belt, the endless belt is depressed. The glow discharge treatment is performed in the space formed.

[0008]

With this structure, the thickness of the nonmagnetic layer portion between the first and second layers can be reduced, and both the saturation flux density of the first layer and the saturation flux density of the second layer can reduce the amount of oxygen introduced. Therefore, since the output can be increased and the noise can be improved at the same time, the C / N at a short wavelength can be further improved.

[0009]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, components which may have the same configuration as the conventional example are denoted by the same reference numerals. Reference numeral 8 denotes an endless belt. The endless belt forms a recess in a part on the vapor deposition side, and the space is used as a glow discharge processing space 9. 10
Is a discharge electrode, which may be plural. 11,12,1
3, 14, 15, and 16 are cooling cans, and the temperature may be appropriately set within a range of -30 ° C to + 30 ° C. Reference numeral 17 schematically shows a vapor flow used for vapor deposition.

The operation of the vapor deposition apparatus configured as described above will be described. Using an endless belt 8 obtained by connecting 70 μm-thick titanium foil in a loop shape, vapor deposition was started at an incident angle of 90 °, a depression was formed at a position where the incident angle was 47 °, and a glow discharge treatment space 9 was formed. The discharge electrode 10 is formed as a bar having a magnet inside, and the discharge electrode 10 has a gap of 0.7 mm.
A voltage of Hz could be applied, oxygen gas was introduced, and the inside was set to about 0.05 Torr to perform discharge treatment. The minimum incident angle is set to 18 degrees, and the mask 6 for defining the minimum incident angle is used.
Oxygen gas was also introduced from the inside. The evaporation source 5 is Co-N
i (Ni: 20 wt%) heated by an electron beam having a power of 30 kV and a maximum output of 150 kW was used. Using such an apparatus, the film 1 made of polyethylene terephthalate having a fine particle coating layer having a thickness of 10 μm is transported along the endless belt 8. First, from near the tangent, Co-Ni
Is deposited. At this time, 0.3 g
(L / min) oxygen gas at 350 V, 0.9 V
The treatment was performed by the glow discharge of (A). The oxygen gas is discharged from the glow discharge processing space 9 to the vapor deposition side through the gap A. The oxygen gas acts on the first layer and also functions to prevent the Co—Ni vapor flow from entering the glow discharge processing space 9. In the two-layer portion, the oxygen introduced from the gas introduction port 7 inside the mask 6 is strongly affected by the gas. Oxygen gas was introduced at 0.9 (l / min). Electron beam heating was performed at 30 kV and 95 kW, and the moving speed of the film 1 was 130 (m / min). First layer and 2
The oxide layer between the layers is 100 ° in this case, and the surface oxide layer of the second layer is 140 °. The first layer is 900Å and 2
The layer thickness is 750 °. Approximately 40 ° of perfluoroarachinic acid was applied on the deposited layer to form an 8 mm wide magnetic tape. The conventional example uses a mask 6 that determines the minimum incident angle of 35 degrees.
The oxygen gas was introduced along the cooling can 2 having a diameter of 1 m by introducing 1.4 (l / min) oxygen gas from the inside. Had a surface oxide layer of 140 °.

Table 1 shows the characteristics of the magnetic recording medium obtained by the method for manufacturing a magnetic recording medium according to the present embodiment and the characteristics of the magnetic recording medium obtained by the conventional method.

[0013]

[Table 1]

As is evident from Table 1, the magnetic recording medium according to this embodiment has excellent effects in terms of C / N characteristics in short-wavelength recording and still durability.

As described above, according to the present embodiment, the endless belt 8 is provided with depressions, and a glow discharge treatment is performed at the depressions to deposit two layers, thereby improving the C / N and improving the stillness. There is an excellent effect that a medium with improved durability can be manufactured.

In this embodiment, the discharge gas is a single oxygen gas. However, the discharge gas may be mixed with other gases such as Ar, Kr, Xe, and N ₂ , and the discharge may be high frequency or direct current. The present invention can also be applied to the manufacture of a magnetic recording medium having a three-layer structure with two recessed portions. As a development, the gas introduction port inside the mask with the minimum incident angle is limited. It may be replaced with a discharge space and also serve as gas introduction. In this case, when the surface oxide layer is formed, the portion due to the introduction of the gas and the oxidation due to the glow discharge overlap, and there is also an advantage that the speed can be further increased.

The vapor deposition is not limited to the oblique vapor deposition, but may be applied to the formation of a perpendicular magnetization film.
Co-Ta, Co-Mn, etc. can be applied to deposition other than Co-Ni.

[0018]

As described above, according to the present invention, a short-wavelength C / N and still durability can be obtained by forming a depression in an endless belt and performing a glow discharge treatment at that portion to perform two-layer deposition. An excellent method for manufacturing a magnetic recording medium can be realized.

[Brief description of the drawings]

FIG. 1 is a main configuration diagram of a vapor deposition apparatus used to carry out a method of manufacturing a magnetic recording medium according to the present invention.

FIG. 2 is a main part configuration diagram of a vapor deposition apparatus used for manufacturing a conventional magnetic recording medium.

[Explanation of symbols]

 8 Endless belt 9 Glow discharge treatment space 10 Discharge electrode

Claims (1)

(57) [Claims] 1. A magnetic recording medium according to claim 1, wherein when depositing two layers on the polymer film moving along the endless belt, a glow discharge treatment is performed in a space formed by recessing the endless belt between the two layers. Production method.