JP2717611B2 - Magnetic recording medium and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic recording medium and a method for manufacturing the same.

[0002]

2. Description of the Related Art A magnetic recording medium, for example, a magnetic tape includes:
A conventional coating tape made by applying a magnetic paint in which magnetic powder is dispersed in a binder on a film that is a non-magnetic support, and a binder using a vacuum evaporation method that deposits a magnetic metal in a vacuum on the film And a vapor-deposited tape in which a magnetic layer of a metal thin film that does not contain any metal is adhered to a nonmagnetic support.

[0003] In recent years, magnetic recording is in the direction of high-density recording, and a vapor-deposited tape is considered to be promising for high-density recording because the magnetic layer does not contain a binder so that the density of a magnetic material can be increased. ing.

[0004]

As a magnetic material for a magnetic layer formed on a non-magnetic support by a vacuum deposition method, a Co-Ni or Co-Cr magnetic alloy has conventionally been used. ing. However, Co, Ni,
Both Cr are expensive and have pollution problems. In this regard, Fe (metallic iron) is inexpensive and has no problem in terms of safety of pollution, but has the disadvantage of low coercive force, which is indispensable for high recording density, and low corrosion resistance.
There is a demand for a magnetic layer material that replaces the Fe-based, Co-Cr-based, and Fe-based materials.

The present invention has been made in view of the above circumstances, and a magnetic recording medium having a magnetic layer having high coercive force and corrosion resistance using Fe as a base at a low cost and having no concern about environmental pollution, and a method of manufacturing the same. The purpose is to provide.

[0006]

For this reason, the magnetic recording medium of the present invention has an Fe content of not less than 99.95% of 7%.
0 to 90 at%, N is 5 to 15 at%, O is 5 to 15 a
The structure was such that an Fe-NO-based ferromagnetic thin film having a composition ratio of t% was formed on a nonmagnetic support. Further, as a method for manufacturing the magnetic recording medium, N ₂ and O ₂ are deposited on a non-magnetic support in a vacuum atmosphere while obliquely depositing Fe with a purity of 99.95% or more on a non-magnetic support. The mixture was irradiated with nitrogen ions and oxygen ions generated by an ion gun from the mixed gas to form a Fe-NO-based ferromagnetic thin film on the nonmagnetic support.

That is, while depositing high-purity Fe on a non-magnetic support using an oblique deposition method, a mixed gas of N ₂ gas and O ₂ gas is ionized by an ion gun to form nitrogen ions and oxygen ions. By irradiating the deposited layer, a Fe—NO—based ferromagnetic film having a predetermined atomic ratio is formed on the nonmagnetic support. Thus, inexpensive Fe-based F
By forming the magnetic layer with an e-NO-based ferromagnetic film, it is less expensive than conventional Co-Ni-based and Co-Cr-based,
Moreover, it does not use environmental pollutants such as Co, Ni, and Cr, and can provide a material having high coercive force and excellent corrosion resistance as compared with Fe alone. Can be fully supported.

Here, the purity of Fe is 9
If it is lower than 9.95%, sufficient corrosion resistance cannot be obtained. This is considered to be due to the influence of impurities contained in Fe. On the other hand, if the content is too small, the coercive force decreases.
When the content of N (nitrogen) is less than 5 at%, the coercive force and corrosion resistance decrease.

As for O (oxygen), the content is 15 at.
%, The saturation magnetic flux density decreases, and 5 at%
If it is less, the coercive force and corrosion resistance will be reduced.

[0010]

An embodiment of the present invention will be described below.
FIG. 1 is a schematic configuration diagram showing an example of a vacuum evaporation apparatus for oblique evaporation used for manufacturing the magnetic recording medium of the present invention.
In FIG. 1, the vacuum chamber 1 is evacuated by a turbo pump 2 and a rotary pump 3. An unwinding roll 4 and a take-up roll 5 are provided in the vacuum vessel 1, and PET (polyethylene terephthalate), polyimide or polyimide is unwound from the unwinding roll 4 and wound up by the winding roll 5. A polymer film 6 as a nonmagnetic support made of aramid or the like travels and moves along a flat cooling plate 7 through which cooling water flows. The cooling plate 7 is supplied with cooling water from a cooling water supply pipe 8 and is drained from a drain pipe (not shown), and the cooling water is circulated and supplied from an external cooling water tank.

As shown in FIG. 1, a crucible 9 made of MgO is placed below the cooling plate 7, and for example, Fe having a purity of 99.95% is put in the crucible 9, and the F
An electron beam is irradiated from an electron beam gun 10 obliquely upward on the e-plane. Thereby, Fe is heated and vaporized. At the time of this Fe deposition, as shown in FIG. 1, the incident angle α of the vapor flow of Fe from the crucible 9 to the film 6 is, for example, 60 ° with respect to the normal direction of the film 6 in this embodiment. In addition, the inclination of the cooling plate 7 is set. By employing such an oblique deposition method, the magnetic properties are improved by the magnetic anisotropy of the magnetic layer.

Further, an ion gun 11 is disposed in a direction perpendicular to the deposition surface of the film 6, and a mixed gas of N ₂ and O ₂ is supplied to the ion gun 11 to generate nitrogen ions and oxygen ions.
While depositing Fe on the film 6, the nitrogen ions and oxygen ions are irradiated on the deposition surface. In the figure
Reference numeral 12 denotes a shielding plate for regulating the range of vapor deposition on the film 6.

Next, an embodiment of a magnetic recording medium manufactured using the vacuum evaporation apparatus of the present embodiment will be described. PE having a thickness of 10 μm and a width of 10 cm using the vacuum evaporation apparatus shown in FIG.
On a film 6 made of T, Fe put in a crucible 9 made of MgO and having a content of 60 cc is heated and vaporized by an electron beam gun 10 to vaporize the vapor flow at an incident angle α (60 °). Ion gun with nitrogen and oxygen ions on the deposition surface
11 to form a magnetic layer having a thickness of 1000 °.
Here, the output of the electron beam gun 10 is 30 kW, and the ion gun 11 is an ECR (Electron Cyclotron Resonance).
Using an ion gun, the output is 400 W, N ₂ gas and O
The supply amount of the mixed gas ₂ gas, N ₂ gas 3 cc / min, O
_Two gases were set at ₂ cc / min, and the running speed of the film 6 was set at 2 m / min.

The magnetic properties of Examples 1 to 5 and Comparative Examples 1 to 5 as shown in Table 1 were obtained by changing the purity of Fe and the composition ratio of Fe—N—O under the above manufacturing conditions. The layers were formed, and their magnetic properties and corrosion resistance were compared. Magnetic properties include coercive force Hc (Oe) and saturation magnetic flux density Bs
(G) was measured. As for the corrosion resistance, the decrease rate ΔBs of the saturation magnetic flux density Bs when immersed in a 5% aqueous solution of NaCl at 20 ° C. for one week was used as a standard.

Here, as the target values of the coercive force Hc (Oe), the saturation magnetic flux density Bs (G) and the reduction rate ΔBs (corrosion resistance), the coercive force Hc is set to 1800 Oe, the saturation magnetic flux density Bs
Was set to 4000 G and the reduction rate ΔBs was set to 9% or less.

[0016]

[Table 1]

As is apparent from Table 1, the purity is 99.95.
% Of Fe 70 to 90 at%, N 5 to 15 at%
% And O in the composition ratio in the range of 5 to 15 at% show sufficiently satisfactory values in terms of coercive force, saturation magnetic flux density and corrosion resistance. In this case, a magnetic layer sufficiently excellent in achieving the above can be obtained. on the other hand,
When the purity of Fe is lower than 99.95%, ΔBs is 9
%, Which indicates that the corrosion resistance is reduced. Also,
When O is excessive, the corrosion resistance shows a satisfactory value, but the saturation magnetic flux density Bs decreases. On the other hand, when O is small, the coercive force Hc and the corrosion resistance are poor. When N is small, the coercive force Hc and the corrosion resistance are still insufficient.

[0018]

As described above, according to the present invention, an excellent magnetic property is obtained by forming a ferromagnetic thin film of Fe--NO--O having a predetermined composition ratio by oblique deposition. An inexpensive magnetic recording medium having characteristics and corrosion resistance can be obtained. Further, since environmental pollutants such as conventional Co, Cr and Ni are not used, it is extremely effective also in terms of environmental protection.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a vacuum evaporation apparatus used for manufacturing a magnetic recording medium of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Turbo pump 3 Rotary pump 4 Unwind roll 5 Take-up roll 6 Film 7 Cooling plate 9 Crucible 10 Electron beam gun 11 Ion gun

Claims (2)

(57) [Claims] (1) Fe having a purity of 99.95% or more is 70 to 90%.
A magnetic recording medium comprising a Fe--NO--based ferromagnetic thin film having a composition ratio of at%, N of 5 to 15 at%, and O of 5 to 15 at% formed on a nonmagnetic support. 2. When forming the ferromagnetic thin film according to claim 1 on a non-magnetic support, Fe having a purity of 99.95% or more is deposited obliquely on the non-magnetic support in a vacuum atmosphere. And irradiating the deposition surface with nitrogen ions and oxygen ions generated by an ion gun from a mixed gas of N ₂ and O ₂ to form a Fe—NO—based ferromagnetic thin film. Manufacturing method of recording medium.