JPH06295423A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To stably obtain high output from a low-frequency range to a high-frequency range by providing the magnetic recording medium with magnetic layers consisting of an MgO film formed on a base material and a film of a prescribed compsn. formed on this MgO film. CONSTITUTION:The magnetic layers consist of the MgO film formed on the base material and the alpha'-Fe16N2 film formed on the MgO film. The alpha'-Fe16N2 film is a compd. having an exceedingly high magnetic flux density but is hardly stably formable and, therefore, the MgO film is formed on the base material and this film is formed thereon. The formation of the magnetic layers is executed by maintaining about 10<-3> to 10<-5>Torr vacuum in a vacuum vessel, allowing a film to travel on a cooling can, forming the MgO film thereon, introducing gaseous nitrogen or air into an ion gun, generating active nitrogen and N<+> and simultaneously irradiating Fe with an Fe sputtering gun, thereby forming the alpha'-Fe16N2 film on the MgO film. The tape with which the high output from the low-frequency range to the high-frequency range is obtainable is thereby produced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a magnetic recording medium.
More specifically, it relates to a magnetic recording medium having a magnetic layer formed by vapor deposition, sputtering or the like.

[0002]

2. Description of the Related Art As a magnetic recording medium, a coating type magnetic recording medium manufactured by coating a magnetic coating material containing magnetic powder on a substrate (film) made of polyethylene terephthalate or the like has been known. Type magnetic recording media have a limit to the filling property of magnetic powder, and it is difficult to increase the density and thinness of the magnetic recording media.

In order to achieve this high density, a magnetic recording medium of a type in which a thin film of a magnetic material is directly formed on a substrate has been proposed, and this type has characteristics which a coating type magnetic recording medium does not have. .

As an example of a magnetic recording medium of a type in which a magnetic layer is directly formed on a substrate, a so-called vapor deposition type magnetic produced by depositing a magnetic material on the substrate and directly forming the magnetic layer on the substrate. There is a recording medium.

In the manufacture of this type of magnetic recording medium, Co--Ni alloys, Co--Cr alloys, Co--Cr--Ni alloys,
The so-called oblique vapor deposition method, in which a magnetic material such as a Co-Cr-Ta alloy, an Fe-Co-Ni alloy, and an Fe-Co alloy is obliquely vapor-deposited on a substrate, is mainly used.

[0006]

However, when actually used as a video tape or the like, the vapor deposition tape has a high residual magnetic flux density, but its output is apt to be insufficient in the low range because of its thin film thickness. Therefore, if this point can be improved, a high output can be stably obtained from a low range to a high range, and a high performance vapor deposition tape can be obtained, and further improvement is desired.

[0007]

In view of the above problems, the inventors of the present invention have conducted earnest research aiming at high output in the low range of vapor deposition type magnetic recording media, and as a result, completed the present invention. .

That is, the present invention relates to Mg formed on a substrate.
The present invention provides a magnetic recording medium having a magnetic layer composed of an O ₂ film and an α ″ -Fe ₁₆ N ₂ film formed on the MgO film.

As a material for the base material of the magnetic recording medium of the present invention, an ordinary non-magnetic support can be used, and polyesters such as polyethylene terephthalate and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene; cellulose triacetate. Cellulose derivatives such as cellulose diacetate; polycarbonate; polyvinyl chloride; polyimide; plastics such as aromatic polyamide. The thickness of these substrates is about 3 to 50 μm.

The magnetic layer of the magnetic recording medium of the present invention comprises an MgO film formed on a substrate and an α ″ formed on the MgO film.
-Fe ₁₆ N ₂ film. Α ''-according to the present invention
Fe ₁₆ N ₂ is known as a compound having a giant magnetic flux density, but it is a soft magnetic material that does not have sufficient coercive force, and since it was difficult to form it stably,
Conventionally, it has not been used for a magnetic recording medium. However, in the present invention, by first forming a film of MgO on the substrate, and forming an α ''-Fe ₁₆ N ₂ film on it,
The α ″ -Fe ₁₆ N ₂ film is easily formed. The reason for this is not clear, but it is thought that the lattice constant of α ″ -Fe ₁₆ N ₂ is similar to that of MgO. In the present invention, it is possible to use any metal compound having a lattice constant similar to that of α ″ -Fe ₁₆ N ₂ , but corrosion resistance, binding property to a base material, and easy availability. Therefore, MgO is most preferably used.

The magnetic recording medium of the present invention has a thickness of 0.
Undercoat layer of 01 to 0.2 μm, thickness 10 to 100 Å
An approximately protective layer, a lubricating layer having a thickness of about 2 to 50 Å, or a back coat layer containing carbon black as a main component and having a thickness of about 0.2 to 1.0 μm may be provided. As a material and a forming method for forming these layers, conventionally known materials can be appropriately used.

A method of manufacturing the magnetic recording medium of the present invention will be briefly described. The magnetic layer of the magnetic recording medium of the present invention is formed by using, for example, a device as shown in FIGS. All of these devices are for forming a three-layer metal film.

The case of using the apparatus of FIG. 1 will be described. This device is for forming a magnetic layer by a sputtering method, and the inside of the vacuum container 9 is a vacuum pump (exhaust system, not shown).
At about 10 ^-3 to 10 ^-5 Torr. Film 6
Runs from the unwind roll 7 on the cooling can 5,
First, an MgO film is formed on the film by the MgO sputter gun 1. Then, nitrogen gas or air is introduced into the ion gun 2 to generate N ^* (active nitrogen) and N ^+, and at the same time Fe is exchanged with F 2
By irradiation with the e-sputter gun 3, an α ″ -Fe ₁₆ N ₂ film is formed on the MgO film previously formed. here,
In addition to α ″ -Fe ₁₆ N ₂ , Fe ₄ N and other iron nitrides are formed, but there is no problem if they are present as long as the effects of the present invention are not impaired. The formation of α ″ -Fe ₁₆ N ₂ in the magnetic layer can be confirmed by, for example, X-ray diffraction. Further, at the time of forming the α ″ -Fe ₁₆ N ₂ film, oxygen gas or air is introduced from the oxygen introducing pipe 4 to improve the coercive force. Furthermore, with another MgO sputter gun 1 ', α''-Fe ₁₆ N ₂
Form a MgO film on the film. Thus MgO−α ″ −Fe
_The film on which the magnetic layer composed of three layers of ₁₆ N ₂ -MgO is formed is wound up by a winding roll 8 and appropriately cut to obtain a desired product.

The apparatus shown in FIG. 3 is for forming three magnetic layers by vapor deposition. In this case as well, Mg is first used.
An O 2 film is formed on the film, and then nitrogen gas or air is introduced into the ion gun to generate N ^* (active nitrogen) and N ^+, and at the same time, metallic iron 12 is evaporated from the crucible 13 and α ″ -Fe
Form a ₁₆ N ₂ film. To improve the coercive force, α ''-
It is preferable to perform oblique vapor deposition while introducing air or oxygen during the formation of the Fe ₁₆ N ₂ film.

As described above, the magnetic layer is formed of MgO-α ''-Fe ₁₆ N ₂
-If three layers of MgO are used, the thickness of the bottom MgO film is 500.
~ 700 Å, intermediate α ''-Fe ₁₆ N ₂ layer thickness is 1500-2000
Å The thickness of the uppermost MgO layer is preferably 100 to 200 Å.

The manufacturing method described above is an example, and it is of course possible to use, for example, three or more magnetic layers or a method other than the above.

[0017]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 A polyethylene terephthalate film having a thickness of 10 μm was set in the apparatus shown in FIG. 3, an MgO film having a thickness of 600 Å was formed first, and then Fe was obliquely vapor-deposited thereon by an ion gun. Irradiate with N ^* (active nitrogen) or N ⁺ , and introduce O ₂ to form α ″ -Fe ₁₆ N ₂ with a thickness of 1700 Å (confirmed by X-ray diffraction), and further on it Form a 100Å MgO film.
Next, this film was cut into a width of 8 mm and placed in an 8 mm cassette for VTR to prepare a magnetic tape. The output of the obtained magnetic tape at 0.75MHz and 10MHz was measured by a device that was modified from a commercially available Hi-8VTR, and it was + 9dB and + 7.3dB, respectively, compared to the commercially available vapor deposition tape.
High output was obtained.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an apparatus for forming a magnetic layer on a substrate by a sputtering method.

FIG. 2 is a schematic view showing an example of an apparatus for forming a magnetic layer on a base material by a sputtering method.

FIG. 3 is a schematic view showing an example of an apparatus for forming a magnetic layer on a base material by a vapor deposition method.

[Explanation of symbols]

 1, 1 '... MgO sputter gun 2 ... Ion gun 3 ... Fe sputter gun 4 ... Oxygen introduction tube 5 ... Cooling can 6 ... Film 7 ... Unwinding roll 8 ... Winding roll 9 ... Vacuum container 10 ... Fe target 11 ... Electron beam 12 ... Metallic iron 13 ... Crucible 14 ... Shield plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Sasaki 2606 Akabane, Kaigai-cho, Haga-gun, Tochigi Kao Corporation Information Science Laboratory

Claims (2)

[Claims] 1. A magnetic recording medium having a magnetic layer comprising a MgO film formed on a substrate and an α ″ -Fe ₁₆ N ₂ film formed on the MgO film. 2. The magnetic recording medium according to claim 1, further comprising a MgO film formed on the α ″ -Fe ₁₆ N ₂ film.