JPH0963055A - Production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the efficiency of ion implantation and to improve a film forming speed at the time of forming magnetic films of an Fe-N system, Fe-N-O system, etc., mainly composed of Fe by introducing reactive gases which are ion sources into the locus of electron beams. SOLUTION: This device has a vacuum vessel 1, a traveling device 2, a crucible 3, an electron beam generator 4 and a gaseous oxygen introducing nozzle 13. The crucible 3 among these has a melting vessel 9 and a magnetic metal 10 is housed in this melting vessel 9. The electron beam generator 4 has an electron gun 11 and emits the electron beams from this electron gun 11. The electron beams are deflected to irradiate the magnetic metal 10 in the melting vessel 9, by which the metal is melted and is kept evaporated. The reactive gases which are the ion sources are blown from the ion source introducing nozzle 13 toward the locus of the electron beams emitted from the electron gun 11. As a result, the gases of the ion sources are converted to plasma and the vapor of the magnetic metal 10 passes the inside of the plasma and the magnetic layers of the Fe-N system, etc., are formed.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a method for manufacturing a magnetic recording medium. More specifically, for example, Fe-N system, Fe-
The present invention relates to a method for manufacturing a magnetic recording medium having a magnetic layer of C-based, Fe-N-O-based, Fe-C-N-O-based or the like.

[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 the 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.

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

Under these circumstances, in order to form a magnetic layer having a low cost and no fear of environmental pollution and having a high coercive force and corrosion resistance, oxygen, nitrogen, and
Ionizing and irradiating a gas such as carbon dioxide or a mixed gas thereof, by a so-called ion-assisted vapor deposition method, Fe-N system, Fe-C system, Fe-N-O system, Fe-C-N-O system Attempts have been made to form magnetic films such as. In this ion assisted vapor deposition method, an electron beam gun 37 irradiates an electron beam onto a metallic Fe 33 housed in a crucible 32 in a vacuum chamber 31 by a device as shown in FIG. In this method, a film having a desired composition is formed by vapor-depositing the film 36 traveling on the roll 35 and irradiating the vapor deposition region with, for example, nitrogen ions and oxygen ions by the ion gun 34.

[0005]

However, it is not desirable to mix such a mixed gas other than the vapor-deposited metal into the vacuum system from the viewpoint of maintaining the degree of vacuum, and
In order to obtain the desired film characteristics, there is a problem that the film forming rate is slow and the productivity tends to be poor.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to achieve the above-mentioned object, and as a result, instead of irradiating ions with an ion gun as in the conventional ion assisted vapor deposition method, when performing vapor deposition. Further, they have found that the film formation rate is improved by irradiating a gas serving as an ion source toward the electron beam for melting the magnetic metal to turn the gas into plasma, and have completed the present invention.

That is, the present invention provides a method for manufacturing a magnetic recording medium, which comprises the step of irradiating a magnetic metal with an electron beam from an electron gun in a vacuum atmosphere to deposit the magnetic metal on a support to form a magnetic layer, A method for manufacturing a magnetic recording medium, which comprises introducing a reactive gas into the trajectory of the electron beam to turn the gas into a plasma to form a magnetic layer containing atoms constituting the reactive gas. Is provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A feature of the method for producing a magnetic recording medium of the present invention is that a reactive gas serving as an ion source is irradiated toward an electron beam for melting a magnetic metal during vapor deposition, As a result, the reactive gas is turned into plasma and the magnetic metal is melted and vaporized, so that the vapor deposition film is formed more uniformly and quickly. The manufacturing method of the present invention will be briefly described below.

FIG. 1 is a schematic view showing an example of a manufacturing apparatus used in the present invention. This device includes a vacuum container 1, a traveling device 2, a crucible 3, an electron beam generator 4, an oxygen gas introduction nozzle 12, and a nozzle 13 for introducing a reactive gas serving as an ion source. The vacuum container 1 has a discharge port 15
Is connected to a vacuum pump (not shown), and a traveling device 2 for traveling a series of materials to be vapor-deposited 5 is arranged in this vacuum container. The inside of the vacuum vessel is usually maintained at a vacuum of about 10 ^-4 to 10 ^-7 Torr. The traveling device comprises a feed roll 6, a winding roll 7 and a cooling can 8. The crucible 3 is usually made of copper and can withstand high temperatures. The crucible 3 is provided with a melting tank (made of MgO, for example) 9,
A magnetic metal 10 is housed inside. Electron beam generator 4
Is equipped with an electron gun 11, which emits an electron beam, and the electron beam is deflected to irradiate the magnetic metal 10 in the melting tank 9. Although the deflection type electron gun is shown in FIG. 1, it is of course possible to use a straight type electron gun, and in that case, a reactive gas as a raw material is introduced as close to the crucible as possible. Is good. When the electron beam is applied to the magnetic metal 10 by the electron gun 11, the magnetic metal 10 melts and continues to evaporate. In the present invention, the electron beam irradiation is performed and the ion source introduction nozzle 13
A reactive gas (that is, a gas containing an element to be present in the magnetic layer) serving as an ion source is blown toward the trajectory of the electron beam emitted from the electron gun 11. As a result, the gas of the ion source is turned into plasma, and the vapor of the magnetic metal passes through the plasma to form a magnetic layer such as Fe-N system.

FIG. 2 schematically shows how the reactive gas is irradiated toward the electron beam from the electron gun. The reactive gas is irradiated from the nozzle 22 toward the trajectory of the electron beam 21,
The electron beam 21 irradiates the magnetic metal 25 in the crucible 25 to melt and evaporate the metal. Of course this is just an example,
Devices other than those shown here may be used as long as they can perform the same operation.

In the manufacturing method of the present invention, as described above, the reactive gas serving as the ion source is irradiated toward the electron beam to turn it into plasma, and at the same time, as in the conventional ion assist method, the reactive gas is removed. By irradiating ions from the introduced ion gun, the film formation rate can be further improved. In addition, in the present invention, the reactive gas means a gas which can be decomposed by an electron beam to be ionized.

In the present invention, examples of the magnetic material to be deposited include ferromagnetic metal materials usually used in the production of magnetic recording media. For example, ferromagnetic metals such as Co, Ni and Fe, and Fe--Co, Fe-Ni, Co-Ni, Fe-Co-Ni, Fe-Cu, Co
-Cu, Co-Au, Co-Y, Co-La, Co-Pr, Co-Gd, Co-
Sm, Co-Pt, Ni-Cu, Mn-Bi, Mn-Sb, Mn-Al, Fe-C
Examples include ferromagnetic alloys such as r, Co-Cr, Ni-Cr, Fe-Co-Cr, and Ni-Co-Cr.

Of these, particularly in the method of the present invention, as described above, Fe-N-based, Fe-C-based, Fe-N-based, mainly Fe is used.
O-based and Fe-C-N-O based magnetic films are suitable, and Fe is preferably used as the magnetic material. The thickness of the vapor-deposited magnetic layer is usually about 0.2 μm.

The reactive gas serving as an ion source is nitrogen gas, oxygen gas, carbon dioxide gas, carbon monoxide gas, methane gas, nitric oxide (NO) gas, etc., and is adjusted to the intended composition of the magnetic layer. Used alone or in combination. At that time, the flow rate of the raw material gas blown toward the electron beam is not limited,
It may be determined in consideration of the type of gas, the film forming speed, the output of the electron gun, and the like.

As the base material for the magnetic recording medium used in the present invention, polyesters such as polyethylene terephthalate and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene; cellulose derivatives such as cellulose triacetate and cellulose diacetate; polycarbonates. Polyvinyl chloride; Polyimide; Plastics such as aromatic polyamide are used. The thickness of these substrates is about 2 to 50 μm.

An undercoat layer having a thickness of about 0.01 to 0.2 μm, a protective layer having a thickness of about 10 to 100 Å, and a thickness of 2 to 50 Å
It is also possible to provide a lubricating layer having a thickness of about 0.2 to 1.0 μm and a back coat layer containing carbon black as a main component and having a thickness of about 0.2 to 1.0 μm. As a raw material for forming these layers, conventionally known materials can be appropriately used.

[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 In the manufacturing apparatus shown in FIG. 1, a PET substrate having a thickness of 6.3 μm was used as a base material.
The film was set, and Fe with a purity of 99.9% was used as the magnetic metal, and the power of the electron gun was set to 10 kW and the metallic iron 10 in the crucible 3 was irradiated. Further, nitrogen gas was irradiated from the gas nozzle 13 toward the trajectory of the electron beam of the electron gun 11 to turn the gas into plasma. The degree of vacuum in the chamber 1 for nitrogen gas is 8 x 10
-Introduced to be ^-4 Torr. Further, oxygen gas was introduced from the oxygen gas introduction nozzle 12 so as to have a partial pressure of 2.5 × 10 ⁻⁴ Torr, and a Fe—N—O 2 -based magnetic layer was formed. In this example, the traveling speed of the film was 2 m / min. The thickness of the magnetic layer thus formed was 1800Å.

On the side opposite to the magnetic layer side of the PET film on which the magnetic layer is formed, carbon black having an average particle diameter of 40 nm is dispersed in a binder resin of urethane prepolymer and vinyl chloride resin. The back coat paint was applied by a die coating method so that the dry film thickness was 0.5 μm, and dried to form a back coat layer. Then perfluoropolyether (FOMBLIN Z DOL,
0.05% by weight of fluorine-containing inert liquid (Florinato FC-77, Sumitomo 3M Limited)
The coating composition diluted and dispersed so as to have the above composition was applied onto the magnetic layer by a die coating method so that the dry film thickness was 20 Å, and dried at 105 ° C to form a lubricating layer.

The PET film was cut into a width of 8 mm and loaded in a high band 8 mm VCR cassette. Then, the film formation rate, coercive force (Hc), saturation magnetic flux density (Bs), film thickness, X-ray diffraction intensity [Fe ₄ N (111), Fe (110), Fe ₄ N (200), () are The Miller index is shown. ] Was measured. Specifically, the coercive force and magnetic moment were measured with an oscillating magnetic force meter at an applied voltage of 10 kOe, and the magnetic layer was dissolved with 0.1N hydrochloric acid to form a step in the film thickness, which was measured by the Rank Taylor Hobson Taristep. The film thickness was measured and the saturation magnetic flux density was measured. Also, X
The line diffraction intensity was evaluated as ◯ when the peak at each angle was confirmed, Δ when weak was confirmed, × when not confirmed, and S when slightly shifted. In addition, as a test of corrosion resistance, a 5% by weight NaCl aqueous solution at 20 ° C for 1 week
The reduction rate ΔBs of Bs when the tape (cut to 8 mm) was immersed was measured. In each test, the target values are Hc of 1800 (Oe) or more, Bs of 5000 (G) or more, and ΔBs of 5%.
Below, the X-ray diffraction intensities are Fe ₄ N (111) (Fe ₄ N peak) and
Fe ₄ N (200) (Fe ₄ N peak) is Δ or more. The results are shown in Table 1.

Example 2 Using the apparatus shown in FIG. 1, a Fe—N—O type magnetic layer was formed in the same manner as in Example 1. However, the nitrogen gas was turned into plasma by the ion gun 14 and irradiated. The conditions are as follows: nitrogen gas is introduced so that the total pressure is 8.7 × 10 ^-4 Torr, a current of 8.0 A is applied to the cathode of the electron gun, and the nitrogen gas is turned into plasma by the emitted thermoelectrons. A potential difference of 500 V was provided between the grids, and nitrogen ions were accelerated to irradiate the Fe deposition surface. Further, under the conditions of Example 1, the power of the electron gun 11 was set to 10 kW. Others are Example 1
Similar to the above, we made a cassette tape for high band 8mm VCR. In this example, the thickness of the magnetic layer was 1850Å. The same evaluation as in Example 1 was performed on the obtained cassette tape. Table 1 shows the results.

Comparative Example 1 In Example 1, the power of the electron gun 11 was set to 10 kW, the nitrogen gas was not introduced through the nozzle 13, and the ion gun 14 was used.
Was irradiated with nitrogen ions. At that time, to the ion gun 14,
Nitrogen gas was introduced so that the total pressure would be 8 × 10 ⁻⁴ Torr.
A high band 8 mm VCR cassette tape was prepared in the same manner as in Example 1 except for the above. In this example, the thickness of the magnetic layer is 1790.
Was Å. The same evaluation as in Example 1 was performed on the obtained cassette tape. Table 1 shows the results.

Comparative Example 2 In Example 1, the nozzle 13 was arranged so as not to cross the electron beam, and nitrogen gas was irradiated toward the tip of the shielding plate 16 so as not to hit the electron beam. A high band 8 mm VCR cassette tape was prepared in the same manner as in Example 1 except for the above. In this example, the thickness of the magnetic layer was 1830Å.
The same evaluation as in Example 1 was performed on the obtained cassette tape. Table 1 shows the results.

[0024]

[Table 1]

[0025]

According to the present invention, Fe containing mainly Fe
It is possible to improve the film formation rate for forming a film having desired characteristics when forming a magnetic film such as a -N system or a Fe-N-O system.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a vacuum vapor deposition apparatus used in the present invention.

FIG. 2 is a schematic diagram showing a main part of a vacuum vapor deposition apparatus used in the present invention.

FIG. 3 is a schematic view showing an example of a conventional ion-assisted vacuum vapor deposition device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Traveling device 3 Crucible 4 Electron beam generator 5 Evaporating material 6 Feed roll 7 Winding roll 8 Cooling can 9 Melting tank 10 Magnetic metal 11 Electron gun 12 Oxygen gas introduction nozzle 13 Reactive gas introduction nozzle 14 Electron gun 15 Outlet port 16 Shield plate

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsumi Sasaki 2606 Akabane Kai, Cho, Haga-gun, Tochigi Prefecture Kao Co., Ltd. (72) Inventor Yuzo Matsuo 2606 Akabane Kai, Cho, Haga-gun, Tochigi Research Institute, Kao Corporation ( 72) Inventor Akira Shiga 2606 Akabane, Kabane-cho, Haga-gun, Tochigi Prefecture Kao Co., Ltd. (72) Inventor Junko Ishikawa 2606 Akabane, Kai-cho, Haga-gun, Tochigi Kao Corporation

Claims (3)

[Claims] 1. A method for producing a magnetic recording medium, comprising the step of irradiating a magnetic metal with an electron beam from an electron gun in a vacuum atmosphere to deposit the magnetic metal on a support to form a magnetic layer, and a reactive gas. Is introduced into the trajectory of the electron beam to turn the gas into a plasma to form a magnetic layer containing atoms forming the reactive gas. 2. The method of manufacturing a magnetic recording medium according to claim 1, wherein the magnetic metal is iron. 3. The method for producing a magnetic recording medium according to claim 1, wherein the reactive gas is one or more selected from nitrogen gas, oxygen gas and carbon gas.