JPH06112043A - Magnetic recording medium and manufacture thereof - Google Patents

Abstract

PURPOSE:To realize a magnetic recording medium provided with a magnetic layer having a high coercive force and a corrosion resistance by a method wherein an Fe-N-O ferromagnetic thin film having a specified compositional ratio of Fe to N to O is formed on a non-magnetic support. CONSTITUTION:An Fe-N-O ferromagnetic thin film having a compositional ratio of 70 to 90at% of Fe having a purity of 99.95% or higher to 5 to 15at% of N to 5 to 15at% of O is formed on a non-magnetic support to obtain a magnetic recording medium. Or when this magnetic recording medium is manufactured, nitrogen ions and oxygen ions produced from the mixed gas of N2 gas and O2 gas are emitted on a deposition surface by an ion gun 11, while the Fe having a purity of 99.95% or higher is deposited on the non-magnetic support from the direction oblique to the support in a vacuum atmosphere and the Fe-N-O ferromagnetic thin film is formed. Thereby, the low-cost magnetic recording medium having superior magnetic characteristics and a corrosion resistance can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium and its manufacturing method.

[0002]

2. Description of the Related Art Magnetic recording media, such as magnetic tape,
A conventional coating tape made by coating 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 deposition method that deposits magnetic metal on the film in vacuum. There is a vapor deposition tape in which a magnetic layer of a metal thin film containing no metal is attached on a non-magnetic support.

In recent years, magnetic recording has tended toward high-density recording, and vapor-deposited tape is promising for high-density recording because it can increase the density of the magnetic material because the magnetic layer does not contain a binder. ing.

[0004]

By the way, as the magnetic material for the magnetic layer formed on the non-magnetic support by the vacuum deposition method, Co--Ni type or Co--Cr type magnetic alloys have been conventionally used. ing. However, Co, Ni,
Both Cr is expensive and has a pollution problem. In this respect, Fe (metallic iron) is inexpensive and has no problem in terms of pollution safety, but it has drawbacks such as low coercive force essential for high recording density and low corrosion resistance.
Materials for magnetic layers, which are an alternative to Fe-based, Co-Cr-based, and Fe, are desired.

The present invention has been made in view of the above circumstances, and is a magnetic recording medium having a magnetic layer having a high coercive force and corrosion resistance, which is made of Fe, which is inexpensive and does not cause environmental pollution, and a method of manufacturing the same. The purpose is to provide.

[0006]

Therefore, the magnetic recording medium of the present invention contains 7% or more of Fe having a purity of 99.95% or more.
0 to 90 at%, N 5 to 15 at%, O 5 to 15 a
A Fe—N—O type ferromagnetic thin film having a composition ratio of t% was formed on a non-magnetic support. As a method of manufacturing the above magnetic recording medium, Fe having a purity of 99.95% or more is vapor-deposited obliquely from a non-magnetic support in a vacuum atmosphere, and N ₂ and O ₂ are vapor-deposited on the vapor-deposited surface. Nitrogen ions and oxygen ions generated by an ion gun were irradiated from the mixed gas of (1) to form a Fe—N—O based ferromagnetic thin film on the non-magnetic support.

That is, while depositing high-purity Fe on the non-magnetic support using the oblique deposition method, a mixed gas of N ₂ gas and O ₂ gas is ionized by an ion gun to generate nitrogen ions and oxygen ions. By irradiating the vapor-deposited layer, a Fe—N—O based ferromagnetic film having a predetermined atomic ratio is formed on the non-magnetic support. Thus, F based on inexpensive Fe
By forming the magnetic layer with an e-N-O type ferromagnetic film, it is cheaper than the conventional Co-Ni type or Co-Cr type,
In addition, without using environmental pollutants such as Co, Ni, and Cr, it is possible to provide a material having a higher coercive force and corrosion resistance than Fe alone. Can be fully accommodated.

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 the influence of impurities contained in Fe. Further, if the content is too small, the coercive force decreases.
Regarding N (nitrogen), when the content is less than 5 at%, the coercive force and the corrosion resistance decrease.

Regarding O (oxygen), the content is 15 at
%, The saturation magnetic flux density decreases, and 5at%
If it is less, the coercive force and the corrosion resistance decrease.

[0010]

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

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

Further, an ion gun 11 is arranged in a direction perpendicular to the vapor 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 deposition surface is irradiated with the nitrogen ions and the oxygen ions. In the figure
Reference numeral 12 is a shielding plate for controlling the vapor deposition range on the film 6.

Next, an example of a magnetic recording medium manufactured by using the vacuum vapor deposition apparatus of this example will be described. Using the vacuum deposition apparatus shown in FIG. 1, PE with a thickness of 10 μm and a width of 10 cm
Fe, which is made of MgO and is contained in a crucible 9 having an internal capacity of 60 cc, is heated and vaporized by an electron beam gun 10 on a film 6 made of T, and its vapor flow is vapor-deposited at an incident angle α (60 °). Ion gun with nitrogen and oxygen ions on the deposition surface
Irradiation was performed at 11 to form a magnetic layer having a thickness of 1000Å.
Here, the output of the electron beam gun 10 is 30 kw, and the ion gun 11 is ECR (Electron Cyclotron Resonance).
Using an ion gun, the output is 400w, N ₂ gas and O
The supply amount of the mixed gas ₂ gas, N ₂ gas 3 cc / min, O
₂ gas was ₂ cc / min, and the running speed of the film 6 was 2 m / min.

Under the above manufacturing conditions, the magnetic properties of Examples 1 to 5 and Comparative Examples 1 to 5 shown in Table 1 in which the purity of Fe and the composition ratio of Fe--N--O were variously changed. Layers were formed and their magnetic properties and corrosion resistance were compared. The magnetic characteristics include coercive force Hc (Oe) and saturation magnetic flux density Bs.
(G) was measured. Regarding the corrosion resistance, the reduction rate ΔBs of the saturation magnetic flux density Bs when immersed in a 5% aqueous solution of NaCl at 20 ° C. for 1 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 1800 Oe and 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 clear from Table 1, the purity is 99.95.
% Or more of Fe at 70 to 90 at% and N at 5 to 15 at
%, O in the magnetic layer of this embodiment having a composition ratio in the range of 5 to 15 at% shows values that are sufficiently satisfied in terms of coercive force, saturation magnetic flux density and corrosion resistance, thus increasing the recording density of the magnetic recording medium. It is possible to obtain a magnetic layer that is sufficiently excellent in achieving the above. on the other hand,
When the purity of Fe is lower than 99.95%, ΔBs is 9
%, The corrosion resistance is lowered. Also,
When O was excessive, the corrosion resistance was satisfactory, but the saturation magnetic flux density Bs was lowered. On the other hand, when the amount of O is small, the coercive force Hc and the corrosion resistance are poor. Further, when N is small, the coercive force Hc and the corrosion resistance are still insufficient.

[0018]

As described above, according to the present invention, by forming a ferromagnetic thin film of Fe--N--O having a predetermined composition ratio by forming the magnetic layer by the oblique deposition method, excellent magnetic properties can be obtained. An inexpensive magnetic recording medium having characteristics and corrosion resistance can be obtained. Further, since conventional environmental pollutants such as Co, Cr, and Ni are not used, it is extremely effective in terms of environmental protection.

[Brief description of drawings]

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

[Explanation of symbols]

 1 Vacuum Container 2 Turbo Pump 3 Rotary Pump 4 Unwinding Roll 5 Winding Roll 6 Film 7 Cooling Plate 9 Crucible 10 Electron Beam Gun 11 Ion Gun

Claims (2)

[Claims] 1. Fe having a purity of 99.95% or more is 70 to 90.
A magnetic recording medium comprising a Fe-N-O 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 non-magnetic support. 2. When forming the ferromagnetic thin film according to claim 1 on a non-magnetic support, Fe with a purity of 99.95% or more is vapor-deposited obliquely from the non-magnetic support in a vacuum atmosphere. Meanwhile, the deposition surface is irradiated 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—N—O type ferromagnetic thin film. Recording medium manufacturing method.