JPS6014407B2 - Method for manufacturing magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the manufacturing method of a metal thin film type magnetic recording medium, and an object thereof is to obtain a magnetic recording medium having excellent characteristics as a long magnetic tape used for magnetic recording. It is something.

Conventionally, in so-called coated tapes in which ferromagnetic powder such as y-Fe203, Cr02, etc. is mixed with a binder, applied, and cured, the binder cannot be removed due to the principle that the ferromagnetic powder is dispersed in the binder. Since then, there has been a limit to the improvement of recording density.

This also applies to improved products using fine alloy particles as magnetic powder, and the superiority of ferromagnetic metal thin film types, which essentially do not require a binder, has been attracting attention. Methods for continuously forming ferromagnetic metal thin films on long substrates include wet plating, vacuum evaporation, sputtering, and ion plating, and trials are currently underway in various fields. The reality is that we have not yet achieved something that is fully satisfactory.

The present invention involves laminating nonmagnetic layers and ferromagnetic layers alternately on a base material made of a polymer molded material or a nonmagnetic metal material by any one of the vacuum evaporation method, ion plating method, and sputtering method. , in order to obtain the required magnetic properties.

When the above-mentioned multilayer structure is obtained by wet plating, the smoothness of copper as a base material has attracted attention for its ability to reduce noise.

However, the copper thin film obtained by wet plating has a problem in adhesion to the substrate. When this copper is made into a thin film on a substrate using vacuum evaporation, etc., an improvement in adhesion strength is observed, but conventional evaporation, sputtering, and ion plating methods require a large coercive force, which is essential for high-density recording. I couldn't find anything that satisfied me.

In view of this point, the present invention is based on an investigation into improvements to the vacuum evaporation method, sputtering method, and ion plating method in order to achieve high coercive force and obtain a low-noise magnetic tape. An example of the cross-sectional structure of a recording medium is shown in FIG. 1, and an example of an apparatus for carrying out the present invention is shown in FIG. 2, and will be described below along with examples.

A non-magnetic layer 2 mainly made of copper, which will be described later, is placed on a base material 1 made of a polymer molded product or a non-magnetic metal material, and a ferromagnetic layer 3 is formed using this as an underlayer. A magnetic recording medium is constructed by forming a multilayer layer 4 and a ferromagnetic layer 5, and disposing a protective layer 6 on the top layer.

Of course, it is clear from the purpose of the present invention that this configuration is not critical, and for convenience of explanation, the configuration shown in FIG. 1 will be described as an example.

Figure 2 shows an example of fabrication to obtain the configuration shown in Figure 1, in which the ion plating method is applied to form the underlayer (non-magnetic layer) and the vacuum evaporation method is applied to form the ferromagnetic layer. However, combinations of these methods, including other sputtering methods, are free and do not limit the present invention. In addition,
The formation of the protective layer 6 is not limited to the vacuum deposition method, but may also be formed by coating a polymeric material, and since it is not an important element that affects the present invention, detailed explanation will be omitted. The inside of the vacuum chamber 7 is continuously evacuated by a vacuum exhaust system 8, and is maintained at an appropriate pressure by adjusting a variable leak valve 9.

Inside the tank 7 are cylindrical cans 10 and 11 that can be cooled and heated.
The evaporation sources 12, 13, and 14 are arranged to face each other. Although a resistance heating type is schematically shown as the evaporation source, a high frequency conductive heating type or an electron beam heating type is industrially superior. 12'
, 13', 14' are heating sources for the evaporation sources 12, 13, 14.

The evaporation sources 12 and 13 are arranged adjacent to each other, one is a copper evaporation source, and the other is a copper evaporation source with high oxygen affinity (or a fast oxidation reaction rate at high temperature) such as Ti, Si, AI, W, Mo, etc. ) is the source of evaporation of the material. If necessary, an alloy with copper may be used as the evaporation material instead of using a binary evaporation source, but a binary evaporation method is more suitable for stable film formation. A discharge electrode 15 is disposed between the can 10 and the evaporation sources 12 and 13, and is configured to perform ion plating. The discharge electrode 15 is connected to a high frequency power source 17 via an insulation introduction terminal 16.
connected to. A mesh electrode 18 at ground potential is disposed on the front surface of the can 10, but these configurations are merely examples, and it goes without saying that any other configuration known in the ion plating art may be used. .

The base material 1, such as a polymer molded product, is arranged so that it can be moved by a conveyance system consisting of winding shafts 19, 20 (rotating in either rotation direction A or B), a loaf system 21, cans 10, 11, etc. be done. 22 is a security signboard.

To obtain the magnetic recording medium shown in FIG.
Then, the ferromagnetic layer 3 is formed by operating the evaporation source 14. Thereafter, the film may be moved in the B direction, rolled up, and then deposited again in the A direction. Specific examples of the present invention will be described below.

Example 1 o Motomura: polyethylene terephthalate film (5R thickness) o Motomura moving speed: low'min ~ 30 m
/mino ion plating method conditions: oxygen partial pressure 8 x lo-5Ton high frequency power 13.58 M ratio 35
0W~600Wo Nonmagnetic material: Cu (99.99%) 7
0% electron beam 10KV, 10KWTi (99.99%
) 30% electron beam 10KV, 10KWo magnetic material: C
o (99.9%) 90% electron beam 10KV, 1 ship WN
i (99.9%) 10% electron beam 10KV, 1 rudder W The magnetic properties of the magnetic recording medium obtained under the above conditions are coercive force e of 520-70, and in the case of Cu alone, e of 300-3
I could only get something worth 30.

Example 2o Base material: N foil (1 tsubo thickness) o Base material moving speed: 15 m/min ~ 20 m/mjno Conditions by ion plating method: Oxygen partial pressure lxlo-
4Ton high frequency power: 13. Circulating MHz 500Wo Non-magnetic material: Cu (99.99%) 80% electron beam side V, 1
Circular WN (99.99%) 20% electron beam 10KV, 1
2KWo magnetic material: Co (99.9%) 90% electron beam loKV, 18KWNi (99.9%) 10% electron beam 10KV, 1isoW The magnetic properties of the magnetic recording medium obtained under the above conditions are coercive force With an e of 500 to 80, the history of Cu alone was 280 to 36K.

In addition, titanium foil, polyimide film, and polyethylene 2-6 naphthalate film were used as base materials to confirm the effects of the present invention.

Additionally, additive materials for non-magnetic materials include Si, Mn, W,
Mo and Cr were confirmed. In order to maintain the smoothness of copper from the viewpoint of noise characteristics, the preferable addition range of the additive was 10% to 20% by weight, but the effect in obtaining high coercive force was confirmed up to 30%. Regarding the magnetic layer, we also investigated simple substances such as Co, Fe, and Nj, their alloys, and alloys with nonmagnetic materials, and the effects of the present invention were confirmed in all cases. As described above, according to the manufacturing method of the present invention, the non-magnetic layer serving as the base of the magnetic layer is formed by simultaneously vaporizing additives selected from materials that are mainly made of copper and have a high oxygen affinity. , it was possible to obtain a magnetic recording medium with high coercive force.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of a magnetic recording medium obtained by the manufacturing method of the present invention, and FIG. 2 is a sectional front view of an embodiment of an apparatus for carrying out the manufacturing method of the invention. 1...Motomura, 2,4...Nonmagnetic layer, 3,5
...Magnetic layer, 12, 13, 14... Evaporation source. Figure 1 Figure 2

Claims (1)

[Claims] 1. In a method of manufacturing a magnetic recording medium in which a magnetic layer is formed by directing a vapor flow of a magnetic material in an oxidizing atmosphere using a polymer molded product or a non-magnetic metal material as a base material, A method for manufacturing a magnetic recording medium, characterized in that the formation is carried out by simultaneously vaporizing additives selected from a material mainly made of copper and having a high affinity for oxygen.