JPH09128751A - Manufacturing method of magnetic recording medium - Google Patents

Abstract

(57) Abstract: It is possible to improve the orientation of magnetic particles formed of a magnetic thin film and obtain good electromagnetic conversion characteristics. In a method of manufacturing a magnetic recording medium in which a ferromagnetic metal thin film is formed on a non-magnetic support by a vacuum thin film forming technique, when the ferromagnetic metal thin film is formed, the non-magnetic support moving and running is used. A permanent magnet is installed inside the supporting cooling can.

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 suitable for use in forming a magnetic layer composed of a ferromagnetic metal thin film on a non-magnetic support by a vacuum thin film forming technique.

[0002]

2. Description of the Related Art For example, in the field of magnetic recording such as a video tape recorder, there is a strong demand for higher density, and as a magnetic recording medium corresponding to this, metal, Co--Ni alloy, Co--Cr alloy is required. A ferromagnetic metal material such as Co, O or Co is directly coated on a non-magnetic support such as a polyester film, polyamide or polyimide film by plating or vacuum thin film forming technology (vacuum deposition method, sputtering method, ion plating method, etc.). A so-called metal magnetic thin film type magnetic recording medium in which a magnetic layer is formed by wearing the magnetic recording medium has been proposed and attracted attention.

This metal magnetic thin film type magnetic recording medium is excellent in coercive force, squareness ratio and the like, and the thickness of the magnetic layer can be made extremely thin, so that the thickness loss during recording demagnetization and reproduction is extremely small and electromagnetic waves at short wavelengths are reduced. Not only is it excellent in conversion characteristics, but since it is not necessary to mix a binder, which is a non-magnetic material, in the magnetic layer, it has various advantages such that the packing density of the magnetic material can be increased. That is, this metal magnetic thin film type magnetic recording medium is considered to be the mainstream of high density magnetic recording because of its superior magnetic characteristics.

In such a magnetic recording medium of metal magnetic thin film type, a vapor deposition tape having a magnetic layer formed by a vacuum vapor deposition method has a high production efficiency and stable characteristics. It is commercialized as a digital micro tape (NT tape).

In this vapor-deposited tape, in order to improve electromagnetic conversion characteristics and achieve higher output, the magnetic material forming the magnetic layer is applied to the surface of the non-magnetic support when forming the magnetic layer. A so-called oblique vapor deposition method is used in which vapor deposition is performed from an oblique direction.

[0006]

Magnetic recording media such as vapor-deposited tapes are promising as high-density recording media, but further improvements in output and noise reduction are required in the future. As a method to improve output and reduce noise,
For example, there is a method of improving the orientation of the magnetic particles that form the magnetic layer formed by vapor deposition.

However, the squareness of the magnetic characteristics of the present vapor deposition tape is at most about 80% even if it is high, and further improvement is desired, but it cannot be expected to be significantly improved by the conventional technology.

Therefore, the present invention has been proposed in view of the above circumstances, and it is possible to improve the orientation of the magnetic particles constituting the magnetic thin film and obtain good electromagnetic conversion characteristics. An object of the present invention is to provide a method of manufacturing a magnetic recording medium that can be used.

[0009]

Means for Solving the Problems The inventors of the present invention have made earnest studies as to achieve the above-mentioned object, and as a result, have established a permanent magnet in the vicinity of the surface of the cooling can inside the vapor deposition apparatus. The present inventors have completed the present invention by discovering that by forming a film, a magnetic thin film having excellent orientation of magnetic particles is formed and the output characteristics as a medium are improved.

That is, the method of manufacturing a magnetic recording medium according to the present invention is the method of manufacturing a magnetic recording medium in which a ferromagnetic metal thin film is formed on a non-magnetic support by a vacuum thin film forming technique. At this time, a permanent magnet is installed inside the cooling can that supports the non-magnetic support that moves and runs.

A permanent magnet is installed near the surface of the cooling can.

The magnetic recording medium to which the present invention is applied includes a so-called metal magnetic thin film type magnetic recording medium in which a ferromagnetic metal thin film is formed as a magnetic layer on a non-magnetic support by a vacuum thin film forming technique. .

In the metal magnetic thin film type magnetic recording medium, the non-magnetic support and the ferromagnetic material forming the ferromagnetic metal thin film are all those conventionally used in this type of magnetic recording medium. It is possible and is not particularly limited.

The magnetic layer may be a single layer film of a ferromagnetic metal thin film made of these ferromagnetic materials or a multi-layer film.

In addition, between the non-magnetic support and the ferromagnetic metal thin film, or in the case of a multilayer film, an underlayer or an intermediate layer is provided in order to improve the adhesive force between layers and control the coercive force. May be provided. Further, for example, the vicinity of the surface of the magnetic layer may be an oxide in order to improve the corrosion resistance.

As a means for forming this ferromagnetic metal thin film, a vacuum vapor deposition method in which the above-mentioned ferromagnetic metal material is heated and evaporated under vacuum to be deposited on the above non-magnetic support is suitable.

In the present invention, when the ferromagnetic metal thin film is formed, a permanent magnet is installed inside a cooling can that supports the non-magnetic support that is moving and running, and the ferromagnetic metal thin film is formed. Immediately after the film, a magnetic field is applied to the ferromagnetic metal thin film. As a result, the orientation of the magnetic particles forming the ferromagnetic metal thin film is improved, and good output characteristics can be obtained.

As the above-mentioned permanent magnet, samarium cobalt is preferable, but neodiboron or the like can be used, and the permanent magnet is not particularly limited.

Of course, the constitution of the magnetic recording medium to which the present invention is applied is not limited to this, and may be changed within the scope of the present invention, for example, a back coat layer may be formed if necessary. There is no problem in forming the undercoat layer or forming various layers such as a lubricant layer on the non-magnetic support. In this case, as the non-magnetic pigment, the resin binder, the material contained in the lubricant layer, etc. contained in the back coat layer, any conventionally known materials can be used.

[0020]

EXAMPLES The present invention will be described below with reference to specific examples, but it goes without saying that the present invention is not limited to these examples.

First, the structure of the continuous winding type vacuum vapor deposition apparatus used when forming the magnetic layer of the magnetic tape manufactured in this embodiment will be described.

As shown in FIG. 1, this continuous winding type vacuum vapor deposition apparatus has a predetermined degree of vacuum inside (10 ^-2 P in this example).
In the vacuum chamber 1 kept in a), the tape-shaped non-magnetic support 4 which is the object to be processed is fixed in the counterclockwise direction from the feed roll 2 which rotates at a constant speed in the counterclockwise direction in FIG. The winding rolls 3 that rotate at high speed are sequentially run.

The non-magnetic support 4 is provided so as to be pulled out to the left in FIG. 1 at a midway point where the non-magnetic support 4 runs from the feed roll 2 side to the take-up roll 3 side. A cooling can 5 having a diameter larger than that of each of the rolls 2 and 3 is provided so as to rotate at a constant speed in the clockwise direction in FIG.

The cooling can 5 has a predetermined temperature (here, -2) by a cooling means (not shown) provided inside.
It was set to 0 ° C. ) Has a configuration to be cooled to
The non-magnetic support 4 running along the outer peripheral surface of the cooling can 5 is prevented from being deformed by heat during vapor deposition.

The feed roll 2, the take-up roll 3 and the cooling can 5 each have a cylindrical shape having a length substantially the same as the width of the nonmagnetic support 4.

Therefore, in this vacuum vapor deposition apparatus, the non-magnetic support 4 is sequentially fed from the feed roll 2, passes along the outer peripheral surface of the cooling can 5, and is further wound on the winding roll 3. It is designed to be taken.

A crucible 6 having a ferromagnetic material 7 filled therein is disposed below the cooling can 5.

On the other hand, an electron gun 10 is externally attached to the head of the vacuum chamber 1 as a heating means, and an electron beam 11 emitted from the electron gun 10 is used as a ferromagnetic material (here, the electron beam 11) in the crucible 6. Co ₁₀₀ is used.) 7 is irradiated on the surface and is heated and melted. Then, the vapor flow X evaporated from the crucible 6 is vapor-deposited on the non-magnetic support 4 which runs along the outer peripheral surface of the cooling can 5, and is formed as a magnetic layer.

Here, a permanent magnet 12 is arranged inside the vicinity of the surface of the cooling can 5 so as to face at least the non-magnetic support 4 on which the vapor flow X is deposited.

The permanent magnet 12 is supported by a support rod 13 attached to the central axis of the cooling can 5, and is installed so as to be at a fixed position regardless of the rotation of the cooling can 5.

A magnetic field is applied to the permanent magnet 12 by a magnetic field generator (not shown). This improves the orientation of the magnetic particles constituting the magnetic thin film by applying a magnetic field immediately after forming the magnetic thin film made of the ferromagnetic material 7 deposited on the non-magnetic support 4 by vapor deposition. In addition, the reproduction output of the obtained medium can be significantly improved.

Although samarium cobalt was used as the permanent magnet 12 in this embodiment, the permanent magnet 12 is not limited to this, and neodiboron, for example, may be used.

In addition, between the cooling can 5 and the crucible 6, in the vicinity of the cooling can 5, an oxygen gas is introduced which is an oxygen gas introduced for refining the particles of the obtained ferromagnetic metal thin film. A mouth 8 is provided. Then, oxygen gas is supplied onto the magnetic layer through the inlet of the oxygen gas inlet 8.

Below the oxygen gas inlet 8,
Area where the oxygen gas inlet 8 is provided and area below the oxygen gas inlet 8 (area where the crucible 6 is provided)
A shielding mask 9 is disposed so as to divide the oxygen gas and the oxygen gas from the oxygen gas inlet 8 so as to prevent the oxygen gas introduced from the oxygen gas inlet 8 from diffusing into a region below the oxygen gas inlet 8. There is.

The shielding mask 9 is arranged so as to cover a part of the non-magnetic support 4 which is moved along the outer peripheral surface of the cooling can 5 on the winding roll 3 side. The vapor flow X evaporated from the crucible 6 is prevented from being deposited on the non-magnetic support 4 in the region covered by the shielding mask 9, so that the vapor flow X with respect to the non-magnetic support 4 is prevented. The angle of incidence is regulated.

Therefore, using a vacuum vapor deposition apparatus having such a structure, a Co film is actually formed by oblique vapor deposition on a base film made of polyethylene terephthalate (PET) under the following conditions. A magnetic layer composed of a single-layer film of a metal thin film was formed so as to have a film thickness of 200 nm.

<Conditions during vapor deposition> Incident angle of vapor flow θ: 90 to 90 ° from the normal direction of the non-magnetic support
45 ° Feeding speed of non-magnetic support: 25 m / min Thickness of magnetic layer: 200 nm Oxygen gas introduction amount: 500 cc / min Then, as shown in FIG. A coat layer was provided.

Subsequently, after applying a rust preventive treatment with a predetermined rust preventive, a lubricant was applied to the surface of the magnetic layer to form a lubricant layer.

Further, the obtained wide base film is
A sample tape was produced by slitting the sample into a width of mm.

With respect to the sample tapes thus produced, the magnetic characteristics and the electromagnetic conversion characteristics were evaluated when the permanent magnets used in the above vacuum vapor deposition apparatus were different in the magnitude of the magnetic field generated. The results are shown in Table 1 below.

[0041]

[Table 1]

Table 1 shows the strength of the magnetic field on the surface of the cooling can during the formation of the magnetic layer of each sample tape, and the magnetic characteristics and electromagnetic conversion characteristics.

The strength of the magnetic field represents a value measured by a Gauss meter in a direction perpendicular to the surface of the cooling can.

The magnetic characteristics were measured with a sample vibration type measuring instrument,
It was evaluated by the measured values in the longitudinal direction and in-plane direction of the medium.

As for the electromagnetic conversion characteristics, a high band 8 mm video deck manufactured by Sony; a modified EV-S900 (trade name) was used, and the relative speed was 3.8 m / sec and the recording frequency was 7.
The reproduction output was measured at MHz. At this time, the recording current was set to a value at which the highest reproduction output was obtained for each sample tape.

As shown in Table 1, it was found that when the magnetic field on the surface of the cooling can was 0.5 mT or more, the squareness ratio and the reproduction output were remarkably improved.

In this embodiment, in order to generate a magnetic field on the surface of the cooling can, a permanent magnet is fixed near the surface inside the cooling can, but the entire surface of the cooling can is synchronized with the cooling can. It is considered that the same effect can be obtained even if the permanent magnet is arranged so as to rotate.

Although the Co film is used as the magnetic layer in the present embodiment, the application of a magnetic field immediately after vapor deposition to improve the orientation of the magnetic thin film as described above is not limited to this. In addition to the Co film, a metal such as Fe or Ni, a Co-Ni-based alloy, a Co-Ni-Pt-based alloy, or F
e-Co-Ni type alloy, Fe-Ni-B type alloy, Fe-
In-plane magnetization recording metal magnetic film made of Co-B type alloy, Fe-Co-Ni-B type alloy, etc., Co-Cr type alloy thin film,
Even when a perpendicular magnetization recording metal magnetic thin film such as a Co—O based thin film is used, it is easily considered to be extremely effective.

Although several methods are already known for using a magnet in the vapor deposition process, the purpose thereof is to prevent the magnetic metal attached to the shielding mask from falling, or to remove the metal powder on the surface of the cooling can. It is clear from this example that the improvement of the orientation of the vapor-deposited layer, which is the effect of the present invention, cannot be realized at these installation positions. The configurations are also very different.

[0050]

As is clear from the above description, in the present invention, when a magnetic layer made of a ferromagnetic metal thin film is formed on a non-magnetic support by a vacuum deposition method, the magnetic layer is disposed in a vapor deposition apparatus. Since the permanent magnet is arranged near the surface inside the cooling can, the magnetic thin film is formed by applying a magnetic field immediately after forming the magnetic thin film formed by vapor deposition on the non-magnetic support. The orientation of particles can be improved.
Therefore, according to the present invention, it is possible to provide a magnetic recording medium having excellent electromagnetic conversion characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration example of a vacuum vapor deposition apparatus used when a magnetic tape is manufactured by applying the present invention.

FIG. 2 is a manufacturing process flowchart for explaining a manufacturing process of a magnetic tape manufactured by applying the present invention.

[Explanation of symbols]

 1 Vacuum tank 2 Feed roll 3 Winding roll 4 Non-magnetic support 5 Cooling can 6 Crucible 7 Ferromagnetic material 8 Oxygen gas inlet 9 Shielding mask 10 Electron gun 11 Electron beam 12 Permanent magnet 13 Support rod

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsutomu Takeda 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (2)

[Claims] 1. A method of manufacturing a magnetic recording medium in which a ferromagnetic metal thin film is formed on a non-magnetic support by a vacuum thin film forming technique, wherein the non-magnetic support moves and moves when the ferromagnetic metal thin film is formed. A method of manufacturing a magnetic recording medium, wherein a permanent magnet is installed inside a cooling can that supports the magnetic recording medium. 2. The method for manufacturing a magnetic recording medium according to claim 1, wherein a permanent magnet is installed near the surface of the cooling can.