JPH0793751A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the magnetic recording medium having high performance by providing one surface of a base with a metallic thin film type magnetic film and the other surface with a metallic thin film type nonmagnetic film and irradiating the nonmagnetic film with ions. CONSTITUTION:Al is packed into a crucible 8 and after the inside of a vessel 1 is evacuated to a prescribed vacuum degree, Al is deposited by heating of an electron gun 9 at a prescribed thickness on the rear surface of the base 6. The base 6 is made to travel from a roll 4 to a roll 5. Gaseous N2 is supplied from a gun 11a by an introducing pipe 12a after the formation of the Al film. The film is then irradiated with gaseous Ar by an introducing pipe 12b from an ion gun 11b. The directions of the guns 11a, 11b are set at different directions. The magnetic metallic film 14 in the crucible is deposited on the opposite surface of the base 6 formed with a back coat film 13 in such a manner. The magnetic film surface is forcibly oxidized by supplying O2 from a gaseous O2. introducing pipe to the vapor deposited part at this time. A prescribed coating material is thereafter applied on the surface of the magnetic film 14 and is dried and a lubricating film 15 is superposed thereon, by which the magnetic tape is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a metal thin film type magnetic recording medium.

[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 metal magnetic 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 type magnetic recording media currently on sale or under development have the structure shown in FIG. In FIG. 4, 21 is a polyethylene terephthalate (PET) film having a thickness of 2 to 50 μm, and 22 is
For example, the thickness is 1500Å which is constructed by vacuum deposition method.
Co-Ni (80% -20%) alloy magnetic film, 23 is a lubricant film, and 24 is a back coat layer. The back coat layer 24 is prepared by dispersing carbon black having a particle size of 10 to 100 nm and a binder resin in a paint, and using a gravure method, a reverse method or a die coating method, and a thickness after drying is 0.5. 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) Improvement of surface property (coefficient of friction μ is, for example, 0.15 to
0.25) to obtain running stability. (3) The front magnetic layer and the back magnetic layer are balanced to prevent warpage.

As described above, even in the metal thin film type magnetic recording medium, the back coat layer is still a coating type. By the way, if the magnetic layer is vacuum-deposited after applying the back coat layer first, degassing (generated from the solvent of the binder) from the back coat layer occurs in a vacuum system, the degree of vacuum is lowered, and vapor deposition does not work well. However, a magnetic film cannot be formed well, and a high-performance magnetic recording medium cannot be obtained.

For this reason, after forming the magnetic film in vacuum, the magnetic film is taken out into the atmosphere and the back coat layer coating material is applied to form the back coat layer. However, this method has a problem that in the step of providing the back coat layer, the magnetic layer is soiled or dust is attached to increase the dropout. Further, although the conductivity of carbon black is good, there is also 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 is an object of the present invention to provide a magnetic recording medium having an excellent antistatic effect, a small dropout, an excellent reproducing characteristic, and a high recording capacity per volume. The purpose of this invention is
A method of manufacturing a magnetic recording medium, comprising a metal thin film type magnetic film on one surface of a support and a metal thin film type non-magnetic film on the other surface, wherein the non-magnetic film is irradiated with ions. And a method of manufacturing a magnetic recording medium.

In carrying out the method of manufacturing the magnetic recording medium, it is preferable that the nonmagnetic film is irradiated with a plurality of types of ions. It is also preferable to irradiate the ions from different directions. In particular, it is preferable to irradiate different ions from different directions. The present invention will be described below. The support of the magnetic recording medium used in the present invention is non-magnetic, and the support is a polyester such as PET,
Polymer materials such as olefin resins such as polyamide, polyimide, polysulfone, polycarbonate and polypropylene, cellulose resins, vinyl chloride resins, inorganic materials such as glass and ceramics, and metal materials such as aluminum alloys are used. .

A metal thin film type magnetic film is provided on one surface of the support by dry plating means such as vapor deposition means and sputtering means. Examples of the material of the evaporated magnetic particles forming the metal magnetic film include Co—Ni alloys, Co—Pt alloys, Co—Ni— besides metals such as Fe, Co, and Ni.
Pt alloy, Fe-Co alloy, Fe-Ni alloy, Fe-C
o-Ni alloy, Fe-Co-B alloy, Co-Ni-Fe
A -B alloy, a Co-Cr alloy, or those containing a metal such as Al is used. Incidentally, it is preferable that an oxidizing gas or the like is supplied at the time of forming the metal magnetic film, and a protective layer made of an oxide film is formed on the surface layer of the metal magnetic film.

A so-called back coat film is provided on the other surface side of the support. In the present invention, this back coat film is a metal thin film type non-magnetic film formed by dry plating means such as vapor deposition means and sputtering means. As the material of the evaporated metal particles forming the back coat film,
For example, Cu-Al-X (where X is one or more selected from the group of Mn, Fe and Ni) based alloys,
Al-Si based alloy, Ti or Ti alloy is used. In addition, metals such as Al, Zn, Sn, Ni and Ag are also used. The metal non-magnetic film has an ion gun (for example, Kaufman type or ECR (high frequency) type).
It is important to irradiate ions with. For example,
An ionizable substance such as N ₂ , O ₂ , Cl ₂ , CH ₄ or Ar is ionized by an ion gun, and the nonmagnetic film is irradiated with this. It is preferable that two or more kinds of ions are irradiated.

The relationship between the magnetic film (metal magnetic film) and the non-magnetic film (back coat film) provided on the surface of the support is that the direction of stress caused by the metal magnetic film and the direction of stress caused by the back coat film are the same. Preferably there is. For example, when the stress generated by the metal magnetic film is of the tensile stress type, it is preferable to select the type (metal composition) and forming conditions of the backcoat film so that the stress expressed by the backcoat film is also of the tensile stress type. . Also, when both films are of the tensile stress type, the absolute value of the stress generated by the back coat film is designed to be larger than the stress expressed by the metal magnetic film, whereby the curl rate is 0 to 15%. , Especially 5
More preferably, it is 15%. If the stress generated by the metal magnetic film is of the compressive stress type, the type of the backcoat film (metal composition) should be such that the stress generated by the backcoat film is also of the compressive stress type.
It is preferable to select the formation conditions. Moreover, when both films are of the compressive stress type, the absolute value of the stress generated by the back coat film is designed to be smaller than the stress expressed by the metal magnetic film, whereby the curl rate is 0 to 15%. It is even more preferable to be 5 to 15%.

The magnetic recording medium having the back coat film provided on the surface opposite to the metal magnetic film as described above has the following characteristics. (1) Surface property is improved (friction coefficient μ is, for example, 0.15 to 0.15).
0.25), and running stability can be achieved. (2) It has sufficient conductivity to prevent static electricity and prevent dust from adhering. (3) Both sides of the support surface can be balanced, and the contact with the magnetic head is improved. (4) High recording capacity per volume and high density recording type. Such features are exhibited.

The formation of the back coat film having such characteristics may be carried out after the formation of the metal magnetic film, first, or simultaneously. 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.

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

[0015]

【Example】

[Embodiment 1] FIGS. 1 and 2 are schematic views of a magnetic recording medium manufacturing apparatus used for carrying out the present invention, and FIG. 3 is a schematic view of the obtained magnetic recording medium. In each figure, 1 is a vacuum vessel, 2 is a turbo pump, 3 is a rotary pump, 4 is a supply side roll of a support (PET film) 6 having a thickness of 9.8 μm, 5 is a take-up side roll of the support 6, 7 is a cooling can, 8 is a crucible, 9 is an electron gun, 10 is a shield, and 11a and 11b are Kaufman type ion guns.

Using such a device, first, the crucible 8
Filled with a non-magnetic metal, such as Al,
After evacuation to a vacuum degree of about 0 ⁻⁴ to 10 ⁻⁶ Torr, non-magnetic metal in the crucible 8 is evaporated by electron beam heating, and 0.04 to 1 μm, for example, 1000 Å thickness on the back surface side of the support 6. Let it pile up. At this time, the support body 6 is running from the supply-side roll 4 to the winding-side roll 5.

At the stage after the nonmagnetic metal film is formed, the nonmagnetic metal film is irradiated with ions from the ion guns 11a and 11b. For example, N ₂ gas is supplied to the ion gun 11a by a gas introduction pipe 12a, and Ar gas is supplied to the ion gun 11b by a gas introduction pipe 12b. Nitrogen ions are supplied from the ion gun 11a to the nonmagnetic metal film. Then, the non-magnetic metal film is irradiated with argon ions from the ion gun 11b. The directions of the ion gun 11a and the ion gun 11b are set to different directions. Therefore, the direction in which the non-magnetic metal film is irradiated with nitrogen ions is different from the direction in which the non-magnetic metal film is irradiated with argon ions. There is.

The support 6 having the back coat film 13 thus formed is moved so that the back coat film 13 side contacts the cooling can of the vacuum vapor deposition apparatus, and the inside of the vacuum vessel is 10 ^-4 to 10 ^-6. After evacuation to a vacuum degree of about Torr, the magnetic metal (80 at% Co-20 at% Ni) in the crucible is evaporated by electron beam heating or the like, and deposited on the surface of the support 6 to a thickness of 1500 Å. Was formed. When the magnetic film 14 was formed, oxygen was supplied to the vapor deposition portion from an oxygen gas introduction tube to forcibly oxidize the surface portion of the magnetic film.

After that, perfluoropolyether (grade: FOMBLIN Z DIAC carboxyl group modified, manufactured by Nippon Montedison Co., Ltd.) was added to a fluorine-inert liquid (Fluorinert, FC-84, manufactured by Sumitomo 3M Co., Ltd.).
The magnetic film 14 is prepared by diluting the paint diluted and dispersed to 1% so that the thickness after drying is about 20Å.
Was coated on the surface of, and dried at 100 ° C., and slit into a predetermined width to obtain a magnetic tape. Reference numeral 15 is a lubricating film.

Then, the original fabric thus obtained is
It was slit into a width of mm to obtain a magnetic tape for 8 mm VTR. [Embodiment 2] The same procedure as in Embodiment 1 is performed except that O ₂ gas is supplied to the ion gun 11a through the gas introduction pipe 12a and Ar gas is supplied to the ion gun 11b through the gas introduction pipe 12b. Got the tape.

[Third Embodiment] The same procedure as in the first embodiment is performed except that CH ₄ gas is supplied to the ion gun 11a through the gas introduction pipe 12a and Ar gas is supplied to the ion gun 11b through the gas introduction pipe 12b. I got a magnetic tape for. [Embodiment 4] The same procedure as in Embodiment 1 is performed except that N ₂ gas is supplied to the ion gun 11a through the gas introduction pipe 12a and Ar gas is not supplied to the ion gun 11b, and a magnetic tape for 8 mm VTR is used. Obtained.

Comparative Example 1 A magnetic tape for 8 mm VTR was prepared in the same manner as in Example 1, except that the N ₂ gas was not supplied to the ion gun 11a and the Ar gas was not supplied to the ion gun 11b. Obtained. [Characteristics] The magnetic tape obtained in each of the above examples was mounted on a reproducing apparatus, and the running property of the tape was examined.
Shown in.

Table-1 Ion gun 11a Ion gun 11b Mobility of non-magnetic surface Gas amount Acceleration voltage Gas amount Acceleration voltage (dynamic friction coefficient μ) Example 1 50sccm 1kV 50sccm 1kV 0.18 10sccm 1kV 10sccm 1kV 0.25 50sccm 0.2kV 50sccm 0.3kV 0.21 10sccm 0.2kV 30sccm 0.5kV 0.25 Example 2 50sccm 1kV 50sccm 1kV 0.15 Example 3 50sccm 1kV 50sccm 1kV 0.20 Example 4 50sccm 1kV − −0.25 Comparative example 1 − − − -0.8 According to this, it can be seen that the magnetic recording medium obtained according to the present invention has a good running property, and has a good recording / reproducing characteristic.

Further, since the back coat film is a metal thin film, it has an excellent antistatic effect, little dropout, and excellent reproduction characteristics.

[0025]

According to the present invention, it is possible to obtain a magnetic recording medium having good running property, excellent antistatic effect, little dropout, and excellent reproducing characteristics.

[Brief description of drawings]

FIG. 1 is an overall schematic view of a magnetic recording medium manufacturing apparatus used for implementing the present invention.

FIG. 2 is a schematic view of a main part of an apparatus for manufacturing a magnetic recording medium used for implementing the present invention.

FIG. 3 is a schematic view of a magnetic recording medium obtained by carrying out the present invention.

FIG. 4 is a schematic diagram of a conventional magnetic recording medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 6 Supports 11a, 11b Ion gun 13 Back coat film 14 Magnetic film 15 Lubricating film

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

Claims (3)

[Claims] 1. A metal thin film type magnetic film on one surface of a support,
A method of manufacturing a magnetic recording medium having a non-magnetic film of a metal thin film type on the other surface, wherein the non-magnetic film is irradiated with ions. 2. The method of manufacturing a magnetic recording medium according to claim 1, wherein the non-magnetic film is irradiated with a plurality of types of ions. 3. The method for manufacturing a magnetic recording medium according to claim 1, wherein the non-magnetic film is irradiated with ions from different directions.