JPH0785445A - Magnetic recording medium and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Purpose] Good running performance and excellent antistatic effect.
It is another object of the present invention to provide a magnetic recording medium having less dropout and excellent reproducing characteristics. A metal thin film type magnetic recording medium comprising a magnetic metal thin film on one side of a support and a nonmagnetic metal thin film on the other side of the support, wherein the nonmagnetic metal thin film forming material is Al.
-A magnetic recording medium using a Si-based alloy.

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]

BACKGROUND OF THE INVENTION Magnetic recording media such as magnetic tapes are of a coating type in which a magnetic coating in which a magnetic powder or a binder is dispersed in a solvent is coated on a film which is a non-magnetic support.
There is a metal thin film type in which magnetic metal particles are deposited on a film without using a binder.

Among these, the metal thin film type magnetic recording medium is said to be suitable for high-density recording because the magnetic layer does not contain a binder and therefore has a high packing density of the magnetic material. By the way, the metal thin film magnetic recording media currently on sale or under development have the structure shown in FIG. In FIG. 3, 31 is a polyethylene terephthalate (PET) film having a thickness of 2 to 50 μm, and 32 is
For example, the thickness is 1500Å which is constructed by vacuum deposition method.
Is a Co-Ni (80% -20%) alloy magnetic film, 33 is a lubricant film, and 34 is a back coat layer. The back coat layer 34 is prepared by dispersing carbon black having a particle diameter of 10 to 100 nm and a binder resin in a coating material and using a gravure method, a reverse method or a die coating method, and the thickness after drying is 0.4. It is formed by coating so as to have a thickness of up to 1.0 μm.

Here, the role of the back coat layer is as follows. (1) By having conductivity, antistatic is achieved,
Prevents adhesion of dust. (2) Surface stability (coefficient of friction) is improved to obtain running stability. (3) The front magnetic layer and the back magnetic layer are balanced to prevent warpage. Thus, even in the metal thin film type magnetic recording medium, the back coat layer is still a coating type.

By the way, when the back coat layer is first applied and then the magnetic layer is vacuum-deposited, degassing (generated from the solvent of the binder) is generated from the back coat layer in a vacuum system, the degree of vacuum is lowered, and vapor deposition is performed. It does not work well, the magnetic thin film cannot be formed well, and a high-performance magnetic recording medium cannot be obtained. Therefore, after forming the magnetic thin film in vacuum, it is taken out into the atmosphere and the back coat layer is applied.

However, this method has a problem that in the step of applying the back coat layer, the magnetic layer becomes dirty or dust is attached to increase the dropout.
Further, although the conductivity of carbon is good, there is a problem that the conductivity is lowered due to the large amount of binder and the antistatic effect is low.

[0007]

DISCLOSURE OF THE INVENTION An object of the present invention is to have good running performance, and
It has an excellent antistatic effect and little dropout,
A magnetic recording medium having excellent reproduction characteristics is provided.
An object of the present invention is a metal thin film type magnetic recording medium in which a magnetic metal thin film is provided on one surface side of a support and a nonmagnetic metal thin film is provided on the other surface side thereof, and the nonmagnetic metal thin film forming material It is achieved by a magnetic recording medium characterized by using an Al-Si alloy.

Further, a magnetic thin metal film is provided on one surface side of the support, and a non-magnetic metal thin film is provided on the other surface side, and the surface of the non-magnetic metal thin film is covered with a protective film made of an oxide film. And a magnetic recording medium characterized in that an Al-Si alloy is used as the non-magnetic metal thin film forming material. A method of manufacturing a metal thin film type magnetic recording medium, wherein a magnetic metal thin film is provided on one surface side of a support and a nonmagnetic metal thin film is provided on the other surface side thereof, wherein the nonmagnetic metal thin film forming material is Al- Si
This is achieved by a method for manufacturing a magnetic recording medium, which comprises using a base alloy as an evaporation source and depositing it on a support.

A method of manufacturing a metal thin film type magnetic recording medium, wherein a magnetic metal thin film is provided on one surface side of the support and a nonmagnetic metal thin film is provided on the other surface side thereof, wherein the nonmagnetic metal thin film forming material is used. The Al-Si based alloy is used as an evaporation source, is deposited on a support, and an oxidizing gas is supplied during this deposition.

In the above invention, the Al content: Si content in the Al--Si alloy is 15 to 70:70.
The ratio (atomic ratio) of ˜15 is preferable. Incidentally, A
It does not matter if a third component that does not significantly change the characteristics of the 1-Si alloy is added. From this point, it is of course possible to include unavoidable impurities. Particularly preferably, the Al content is 25 to 50 at%.
And the Si content is 25 to 55 at%.

Further, the electric resistance value of the non-magnetic metal thin film side in the magnetic recording medium is 5 to 10 ⁵ Ω / sq. It is preferable that it is configured as follows. For example, when the supply amount of the oxidizing gas is 5 to 10 ⁵ Ω / sq. Is preferably controlled so that Hereinafter, the present invention will be described in detail.

First, in view of the fact that the problem with the conventional backcoat layer has arisen from the adoption of the coating means, if the so-called backcoat layer itself is constituted by a thin film forming means similar to the magnetic metal thin film, the problems up to this point will be solved. Came to the idea that would be solved. However, depending on the non-magnetic metal thin film provided on the surface opposite to the magnetic metal thin film,
It turned out that it wasn't what I expected. Therefore, as a result of earnestly studying the non-magnetic metal thin film forming material, it has become clear that the non-magnetic metal thin film forming material is an Al-Si alloy. For example, even if a Cu-Al alloy material or a pure Al material is used, the expected result was not obtained at all.

The magnetic recording medium in which the non-magnetic metal thin film is formed by using such an alloy material has (1) sufficient conductivity, antistatic property and dust adhesion are prevented. (2) The surface property is improved and running stability can be achieved. (3) Both sides of the support surface can be balanced and warpage can be prevented from occurring. That is the feature.

The formation of the non-magnetic metal thin film having such characteristics can be performed in the same manner as the formation of the magnetic metal thin film. For example, the formation of the non-magnetic metal thin film and the formation of the magnetic metal thin film may be performed at the same time, the formation of the magnetic metal thin film may be performed after the formation of the non-magnetic metal thin film, or the formation of the magnetic metal thin film may be performed. You may form a nonmagnetic metal thin film.
When performing the process separately, one thin film should be formed and wound on a roll, and then the roll should be taken out of the vacuum device into the atmosphere and loaded into another vacuum device to form the other thin film. However, there is no problem such as adhesion of dust. Further, for forming these metal thin films, means such as vacuum vapor deposition and sputtering can be appropriately adopted.

The present invention will be described below with reference to specific examples.

[0016]

1 is a schematic view of an apparatus (vacuum vapor deposition apparatus) used for manufacturing a magnetic recording medium according to the present invention, and FIG. 2 is a sectional view of a magnetic recording medium constructed using this apparatus. . In FIG. 1, 1 is a vacuum container, 2 is a turbo pump, 3 is a rotary pump, 4 is a supply side roll of the support body 6, 5 is a winding side roll of the support body 6, 7 is a cooling can, 8 is a crucible, 9
Is an electron gun, 10 is a shielding plate, and 11 is an oxygen gas introduction tube. Since the structure of this vacuum vapor deposition apparatus is substantially the same as that of the conventional one, detailed description thereof will be omitted.

Then, using such a device, first,
The magnetic metal thin film 20 is formed on the support 6. The support 6 is non-magnetic, and the support 6 is made of polyester, polyamide such as PET, polyamide, polyimide, polysulfone, polycarbonate, olefin resin such as polypropylene, cellulose resin, vinyl chloride resin, or the like. Molecular materials, inorganic materials such as glass and ceramics, and metal materials such as aluminum alloys are used. If necessary, a magnetic layer (magnetic metal thin film) may be formed on the support 6 surface.
Is provided with an undercoat layer for improving the adhesion. That is, by appropriately roughening the surface roughness, for example, the adhesion of the magnetic metal thin film formed by the oblique deposition method is improved, and the surface roughness of the magnetic recording medium surface is moderated to improve the running property. Therefore, for example, SiO
_The thickness including particles such as ₂ is 0.005-0.1 μm
The undercoat layer is formed by providing the coating film.

As the magnetic metal with which the crucible 8 is filled,
For example, in addition to metals such as Fe, Co and Ni, Co-Ni alloys, Co-Pt alloys, Co-Ni-Pt alloys, Fe-C
o alloy, Fe-Ni alloy, Fe-Co-Ni alloy, Fe
-Co-B alloy, Co-Ni-Fe-B alloy, Co-C
Examples thereof include r alloys and alloys containing a metal such as Al.

Then, the inside of the vacuum vessel 1 is 10 ^-4 to 10 ^-6 T
After evacuation to a vacuum degree of about orr, the magnetic metal in the crucible 8 is evaporated by electron beam heating, and the magnetic metal having a thickness of 0.04 to 1 μm is deposited on the support 6 such as a PET film. A metal thin film type magnetic recording medium is manufactured. When forming the magnetic metal thin film 20,
It is preferable that oxygen is supplied to the vapor deposition portion from the oxygen gas introduction pipe 11 and the surface layer portion of the magnetic metal thin film 20 is oxidized by forced oxidation to form a protective layer of an oxide film. The thickness of the protective layer composed of this oxide film is about several tens of liters, and an oxide film of this thickness may be composed of natural oxidation. In some cases, no action is required.

After that, the winding-side roll 5 is taken out, and this is arranged on the support portion of the supply-side roll so that the side on which the magnetic metal thin film 20 is formed abuts the cooling can 7, and the crucible 8 is formed. After filling the Al-Si alloy and evacuating the inside of the vacuum chamber 1 to a vacuum degree of about 10 ^-4 to 10 ^-6 Torr, the non-magnetic metal in the crucible 8 is evaporated by electron beam heating, and the support 6 A non-magnetic metal having a thickness of 0.04 to 1 μm is deposited on the other surface side. When the nonmagnetic metal thin film 21 is formed, oxygen is supplied to the vapor deposition portion from the oxygen gas introduction pipe 11 and forced oxidation is performed to oxidize the surface layer portion of the nonmagnetic metal thin film 21. The amount of oxygen gas introduced from the oxygen gas introduction pipe 11 is 99.998% pure oxygen 2 per minute.
It is a ratio of 5 ml. The amount of oxygen introduced can be adjusted by a flow rate control valve (not shown).

Fluorine perfluoropolyether (grade: FOMBLIN ZDIAC carboxyl group modified, manufactured by Nippon Montedison Co., Ltd.) was diluted to 0.1% in a fluorine inert liquid (Fluorinert, FC-84, manufactured by Sumitomo 3M Limited). -The dispersed coating material is applied to the surface of the magnetic metal thin film 20 by a die coating method so that the thickness after drying is about 20Å, dried at 100 ° C, and slit into a predetermined width to obtain a magnetic tape. It was

The magnetic tape thus obtained was examined for dropout, warpage, and surface electric resistance, hardness, and elongation of the nonmagnetic metal thin film 21.
The results are shown in Tables 1 and 2 below. Table-1 Magnetic metal thin film Non-magnetic metal thin film Co Ni thickness Al Si O thickness Example 1 80wt% 20wt% 3000Å 26.3at% 48.7at% 25at% 1000Å Example 2 80wt% 20wt% 2000Å 30.0at% 45.0at% 25at% 1000Å Example 3 80wt% 20wt% 2000Å 31.0at% 44.0at% 25at% 1000Å Example 4 80wt% 20wt% 2000Å 32.0at% 43.0at% 25at% 1000Å Example 5 80wt% 20wt% 1000Å 33.8at% 41.2at % 25at% 1000Å Comparative Example 1 80wt% 20wt% 2000Å 75at% − 25at% 1000Å Comparative Example 2 80wt% 20wt% 2000Å 31at% 44at% ^* Cu 25wt% 1000Å Comparative Example 3 80wt% 20wt% 2000Å ** 5000Å * Comparative Example 2 The non-magnetic metal thin film of is a case where Al-Cu is used.

** The non-magnetic metal thin film in Comparative Example 3 is a conventional coating type back coat. Table-2 Dropout Warp condition Electric resistance Hardness Envelope (pieces) (Ω / sq.) (%) Example 15 0.03 900 115 95 Example 2 8 0.05 870 100 100 90 Example 3 7 0.04 820 97 91 Example 4 6 0.03 760 95 93 Example 5 8 0.05 700 700 90 90 Comparative Example 1 10 0.18 200 60 40 Comparative Example 2 10 0.15 150 75 55 55 Comparative Example 3 13 0.05 5 × 10 ⁶ −90 * Dropout measurement was performed by measuring a dropout of ¹⁶ dB in 10 μs as a dropout counter. Sought as a dropout.

* The degree of warpage is expressed as (warp height (depth) / tape width). * Hardness is indicated by the hardness of Example 2 as 100 and measured by a push-in micro hardness meter. According to this, even in a metal thin film type magnetic recording medium in which a magnetic metal thin film is provided on one surface side of a support and a non-magnetic metal thin film is provided on the other surface side, that is, a conventional magnetic layer and a back coat layer It can be seen that even if is composed of a metal thin film, it is not satisfactory depending on the composition of the metal thin film forming the back coat layer. For example, when pure Al is used for the metal thin film that constitutes the back coat layer, or when an Al-Cu alloy is used, the characteristics as when an Al-Si alloy is used are extremely excellent. It turns out that it has not been done.

The degree of warpage is preferably 0.1 or less, and the present invention is satisfied also in this respect. The head of the envelope is a magnetic tape.
It is an output waveform obtained during tracing, and it is known that when the amount of warp of the tape is large, the waveform appearing on the oscilloscope collapses from a rectangular shape, which is not preferable in terms of characteristics. Is 9
A value of 0% or more is shown, which shows that it is excellent.

The envelope is an output waveform obtained while the video head traces one tape. When the amount of warp of the tape is large, the waveform that should appear on the oscilloscope as shown in FIG. 3 becomes as shown in FIG. 4, which is not preferable in terms of characteristics. Therefore, a / b × 100
The closer the index represented by (%) to 100, the better.

[0027]

[Effect] According to the present invention, there is no warp, the running property is good, the dropout is small, and the recording and reproducing characteristics are excellent.

[Brief description of drawings]

FIG. 1 is a schematic view of a vacuum vapor deposition apparatus used for manufacturing a magnetic recording medium according to the present invention.

FIG. 2 is a sectional view of a magnetic recording medium according to the present invention.

FIG. 3 is an explanatory diagram of an output waveform

FIG. 4 is an explanatory diagram of an output waveform

FIG. 5 is a sectional view of a conventional metal thin film type magnetic recording medium.

[Explanation of symbols]

 6 Support 20 Magnetic metal thin film 21 Non-magnetic metal thin film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Shiga 2606 Akabane, Kai-cho, Haga-gun, Tochigi Prefecture Kao Co., Ltd.

Claims (7)

[Claims] 1. A metal thin film type magnetic recording medium comprising a magnetic metal thin film on one surface side of a support and a nonmagnetic metal thin film on the other surface side, wherein the nonmagnetic metal thin film forming material is Al- A magnetic recording medium comprising a Si-based alloy. 2. A metal thin film type in which a magnetic metal thin film is provided on one surface side of a support and a nonmagnetic metal thin film is provided on the other surface side, and the surface of the nonmagnetic metal thin film is covered with a protective film made of an oxide film. 2. The magnetic recording medium according to claim 1, wherein an Al—Si alloy is used as the non-magnetic metal thin film forming material. 3. Al content in an Al-Si alloy:
Ratio of Si content 15 to 70:70 to 15 (atomic ratio)
The magnetic recording medium according to claim 1 or 2, wherein 4. The electric resistance value of the non-magnetic metal thin film side of the magnetic recording medium is 5 to 10 ⁵ Ω / sq. The magnetic recording medium according to claim 1 or 2, wherein 5. A method of manufacturing a metal thin film type magnetic recording medium, comprising a magnetic metal thin film on one side of a support and a nonmagnetic metal thin film on the other side, the nonmagnetic metal thin film forming material. As a method of manufacturing a magnetic recording medium, the Al-Si alloy is used as an evaporation source and deposited on a support. 6. A method of manufacturing a metal thin film type magnetic recording medium, comprising a magnetic metal thin film on one surface side of a support and a non-magnetic metal thin film on the other surface side thereof, the non-magnetic metal thin film forming material. As a method of manufacturing a magnetic recording medium, an Al-Si alloy is used as an evaporation source to deposit on a support, and an oxidizing gas is supplied during the deposition. 7. The electric resistance value of the non-magnetic metal thin film side of the magnetic recording medium is 5 to 10 ⁵ Ω / sq. 7. The method of manufacturing a magnetic recording medium according to claim 6, wherein the supply amount of the oxidizing gas is controlled so that