JPH0935235A - Magnetic recording medium and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium having further improved durability and oxidation resistance, especially a magnetic recording medium with a magnetic layer based on iron and contg. nitrogen or carbon. SOLUTION: A magnetic layer contg. iron and nitrogen or carbon, e.g. an Fe-N-O magnetic layer 2 is formed on a substrate 1 by an ion assist physical vapor deposition method in a vacuum atmosphere. A nickel layer 3 is formed on the magnetic layer 2 by a physical vapor deposition method.

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. More specifically, Fe-N-O system, Fe
The present invention relates to a magnetic recording medium having a magnetic layer containing iron and nitrogen or carbon such as —N, Fe—C, and Fe—C—N—O and a method for manufacturing the same.

[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, the base is made of Fe which is inexpensive and does not cause environmental pollution, and in order to form a magnetic layer having a high coercive force and corrosion resistance, oxygen, nitrogen,
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. This ion-assisted vapor deposition method uses an apparatus as shown in FIG. 2 to irradiate a metallic Fe with an electron beam from an electron beam gun to heat and vaporize the Fe to vaporize it on the surface of a film running on a cooling plate. Then, for example, a desired film is formed by irradiating the vapor deposition region with nitrogen ions and oxygen ions.

[0005]

However, such Fe-N-based, Fe-C-based, Fe-N-O-based, Fe-C-N-O-based magnetic films obtain desired film characteristics. Therefore, it is necessary to reduce the film formation rate, which is disadvantageous in terms of production efficiency. Also,
It has been pointed out that the oxidation resistance to nitrogen oxides (NO _x ) and sulfur oxides (SO _x ) is low. Further, since Fe ₄ N and the like are interstitial solid solutions, the quality may be deteriorated due to diffusion of constituent components after long-term storage. Further, a plastic film such as PET (polyethylene terephthalate) is usually used as the base film of the magnetic recording medium, but oxygen, which is a component of the base film, may diffuse to affect the magnetic layer. Under such circumstances, a vapor deposition type magnetic recording medium having further excellent stability and durability is desired.

[0006]

The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, have found that a nickel layer is formed on an iron-nitrogen-based or iron-carbon-based magnetic layer mainly containing iron. It was found that by forming the same, a magnetic recording medium having more excellent durability and oxidation resistance can be obtained at the same film forming rate as in the past, and the present invention has been completed.

That is, the present invention provides a magnetic recording medium having a support, a magnetic layer containing iron and nitrogen or carbon formed on the support, and a nickel layer formed on the magnetic layer. It is a thing. Such a magnetic recording medium comprises a step of forming a magnetic layer containing iron and nitrogen or carbon on a support by an ion assisted physical vapor deposition method in a vacuum atmosphere, and then forming a nickel layer on the magnetic layer by a physical vapor deposition method. It is obtained by the manufacturing method characterized by including.

The present invention also provides a support, a nickel layer formed on the support, a magnetic layer containing iron and nitrogen or carbon formed on the nickel layer, and a magnetic layer formed on the magnetic layer. And a magnetic recording medium having a nickel layer. Such a magnetic recording medium forms a nickel layer on a support by a physical vapor deposition method in a vacuum atmosphere,
Next, a method of manufacturing, comprising a step of forming a magnetic layer containing iron and nitrogen or carbon on the nickel layer by an ion assisted physical vapor deposition method, and then forming a nickel layer on the magnetic layer by a physical vapor deposition method. Is obtained by

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A schematic view showing the structure of a magnetic recording medium of the present invention is shown in FIG. This magnetic recording medium has a magnetic layer containing iron and nitrogen or carbon formed on the support 1 by an ion assisted physical vapor deposition method in a vacuum atmosphere, for example, a magnetic layer 2 composed of a Fe—N—O based thin film. In addition, the nickel layer 3 is further formed on the nickel layer 3 so that the influence of the outside on the magnetic layer can be shielded and the diffusion of nitrogen or carbon from the inside of the magnetic layer to the outside can be prevented. Therefore, it is possible to obtain a magnetic recording medium which is further excellent in durability and oxidation resistance at a film forming rate equivalent to that of the conventional one.

Another example of the magnetic recording medium of the present invention is shown in FIG. This magnetic recording medium comprises a nickel layer 4 formed on a support 1 by a physical vapor deposition method, and a magnetic layer containing iron and nitrogen or carbon formed on the nickel layer 4 by an ion assisted physical vapor deposition method, such as Fe. −N−O
The magnetic layer 2 made of a system thin film and the nickel layer 3 formed on the magnetic layer 2 by a physical vapor deposition method are further characterized, and as described above, the influence from the outside on the magnetic layer can be blocked. At the same time, the influence of the diffusion of oxygen from the base film can be blocked, and the magnetic recording medium is further excellent in stability.

The method for producing the magnetic recording medium of the present invention will be described below by taking as an example the case where a magnetic layer made of a Fe--N--O type thin film is formed as the magnetic layer. FIG. 2 is a schematic view showing an example of a manufacturing apparatus used in the present invention. FIG.
Inside, 21 is a vacuum container, 22 is a cooling can roll, 23 and 23 'are sputter devices, 24 is an ion gun, 25 is an electron gun, 26 is a crucible, 27 is an oxygen gas introduction pipe, 28 is a gas introduction pipe, and 29 is a shield. Plate, 30 unwinding roll, 31 winding roll, 32 support, 33
Is a gas introduction pipe.

The vacuum container 1 has four internal parts (A) to (D).
It is defined by two chambers, and the vacuum degree is maintained independently by differential evacuation. The discharge port of the vacuum container 1 is connected to a vacuum pump (not shown). The sputtering devices 23 and 23 'are for depositing nickel. The support 32 runs in the chamber (B) through the chamber (A), and a magnetic layer is formed on the support 32.
The crucible 26 disposed in the chamber (B) is usually made of copper so that it can withstand high temperatures. This crucible
The 26 is usually equipped with a melting tank (for example, made of MgO) and contains metallic iron in this melting tank. An electron beam is emitted from the electron gun 25 to irradiate the metal iron in the crucible 26. When the electron beam is applied to the metallic iron by the electron gun 25,
Metallic iron melts and continues to evaporate. For example, nitrogen ions or oxygen ions are irradiated from the ion gun 24 toward the metal iron vapor deposition surface to form a magnetic layer having a desired structure. The “ion assist” in the present invention includes the case where nitrogen, oxygen, etc. are supplied in the form of gas instead of the form of ions, and the case where ions and gas are supplied in combination. In particular, relatively highly active oxygen may be introduced from the nozzle 27 to the vapor deposition surface. In the present invention, the magnetic layer is mainly composed of iron and contains nitrogen or carbon, and may contain both nitrogen and carbon. Further, it is possible to contain oxygen and other elements as necessary. Nitrogen and carbon are ionized by supplying a gas serving as an appropriate ion source to the ion gun and supplied to the vapor deposition surface of the magnetic layer. Nitrogen gas, CH ₄ , C ₆ H is used as the ion source gas.
_{6, H 2, C 6 H} 14, C 6 H 12, C 3 H 8, an oxygen gas or the like, the flow rate of the raw material gas in accordance with the traveling speed of the composition and the support of the magnetic layer for the purpose, ratios, etc. Just decide.

The support 32 on which the magnetic layer is formed runs in the chamber (C), and a nickel layer is formed on the magnetic layer by the sputtering device 23 '. Argon gas is supplied from the nozzle 28 in the chamber (C). The thickness of the nickel layer formed on the magnetic layer is not limited, but is preferably about 50 to 180 Å. When forming a nickel layer on the support,
The thickness is preferably about 80 to 500Å.

In the present invention, as the physical vapor deposition means for forming the magnetic layer or the nickel layer and the ion gun, conventionally known ones can be used.

In the present invention, the thickness of the magnetic layer is not limited, but is about 1000 to 2500Å. The magnetic layer may have a single layer or a multi-layer structure. In the case of a multilayer structure, the composition of each magnetic layer may be the same or different. For example, when the magnetic layer has a two-layer structure, the lower layer (layer near the support)
The thickness of the magnetic layer is preferably 1000 to 2000Å, and the thickness of the upper magnetic layer (layer far from the support) is preferably 50 to 1000Å. When the magnetic layer has a three-layer structure, the thickness of the lower magnetic layer is preferably 100 to 2000Å, and the thickness of the intermediate magnetic layer is
100 ~ 1000Å is preferred, the thickness of the upper magnetic layer is 50 ~ 10
00Å is preferred. It is preferable that the number of magnetic layers is large in order to support high frequency recording, but it is considered that two to five layers are suitable as a practical range.

The material for the support of the magnetic recording medium of the present invention includes polyesters such as polyethylene terephthalate and polyethylene naphthalate; polyethylene,
Polyolefin such as polypropylene; Cellulose derivative such as cellulose triacetate and cellulose diacetate; Polycarbonate; Polyvinyl chloride; Polyimide;
Plastics such as aromatic polyamide are used. The thickness of these substrates is about 3 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.

[0018]

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

Example 1 (1) Manufacture of magnetic recording medium A PET film having a thickness of 6.5 μm was set in the manufacturing apparatus shown in FIG. 2, Fe of 99.95% purity was housed in the crucible 26, and the electron gun 25 The output of 3 kW was applied to the Fe in the crucible 26.
Moreover, the total pressure of the ion gun 24 in the chamber (B) is 7 × 10 ^−4.
Nitrogen gas was supplied so as to obtain Torr, nitrogen ions were generated and irradiated on the vapor deposition surface, and oxygen gas was introduced from the nozzle 27 onto the vapor deposition surface so that the partial pressure was 2 × 10 ⁻⁵ Torr.
As a result, a Fe-N-O magnetic layer was formed on the film. Then, in the chamber (C), argon gas was supplied from the nozzle 28 so that the partial pressure was 2 × 10 ⁻⁴ Torr, and nickel was vapor-deposited on the magnetic layer by the sputtering device 23 ′ to form a nickel layer. The running speed of PET film is
It was 0.5 m / min. Further, sputtering is not performed in the chamber (A). In addition, a carbon black having an average particle size of 40 nm is dispersed in a binder resin of urethane prepolymer and vinyl chloride resin on the surface opposite to the magnetic layer surface of the PET film on which the magnetic layer is formed for back coating. Die coating method is used to dry film thickness of 0.5 μm
And the coating solution was 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.

(2) Performance Evaluation of Magnetic Recording Medium The PET film having the magnetic layer, the nickel layer and the back coat layer formed as described above was cut to a width of 8 mm to obtain a high band 8
It was loaded in the mmVCR cassette. Then, the film formation rate, coercive force (Hc), saturation magnetic flux density (Bs), film thickness (Å), X-ray diffraction intensity (Fe ₄ N (111), Fe (110), Fe ₄ N (200), ( () Indicates Miller index. ] 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,
The evaluation of the X-ray diffraction intensity was ◯ when the peak of each angle was confirmed, Δ when weak was confirmed, × when not confirmed, and S when slightly shifted. As a corrosion resistance test, the Bs reduction rate ΔBs when the tape (cut into 8 mm pieces) was immersed in a 5 wt% NaCl aqueous solution at 20 ° C. for 1 week was measured. Also, as an oxidation resistance test,
The Bs reduction rate ΔBs after standing for 24 hours in a 50 ppm SO _X gas atmosphere was measured. Furthermore, as a durability test, a track width of 25 μm high band 8 mm MIG was measured by the head tester method.
The time ΔT (minute) until the output decreased by 10 dB at a relative speed of 10 m / sec was measured by the head. The results of these evaluations are shown in Table 1.

Example 2 A magnetic recording medium was manufactured in the same manner as in Example 1 using the apparatus shown in FIG. However, in chamber (A), a nickel layer is formed on a PET film by sputtering, then a magnetic layer is formed in chamber (B), and then chamber (C).
To form a nickel layer on the magnetic layer. At that time, the total pressure of argon gas from the nozzle 33 into the chamber (A) is 2 × 10 ⁻³ To.
Nickel was sputtered while being introduced so as to have a rate of rr to form a nickel layer having a thickness of 130 Å on the film. Also,
The output of the electron gun 25 is 10 kW and the traveling speed of the film is 0.6
m / min. A high band 8 mm VCR cassette tape having a nickel-magnetic layer-nickel structure was prepared in the same manner as in Example 1 except for the above. The same evaluation as in Example 1 was performed on the obtained cassette tape. Table 1 shows the results.

Comparative Example 1 Using the apparatus shown in FIG. 1, a magnetic recording medium was manufactured in the same manner as in Example 1. However, the nickel layer was not formed in the chamber (C). A high band 8 mm VCR cassette tape was prepared in the same manner as in Example 1 except for the above.
The same evaluation as in Example 1 was performed on the obtained cassette tape. Table 1 shows the results.

[0023]

[Table 1]

[0024]

According to the present invention, a magnetic layer containing iron and nitrogen or carbon, such as an Fe-N-O magnetic layer, whose durability and oxidation resistance are remarkably improved at a film formation rate equivalent to that of the prior art. ,
A magnetic recording medium having an Fe-N-C-O based magnetic layer can be manufactured.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the structure of a magnetic recording medium of the present invention.

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

[Explanation of symbols]

 1 Support 2 Fe-N-O System Magnetic Layer 3 Nickel Layer 4 Nickel Layer

Front page continuation (72) Inventor Katsumi Sasaki 2606 Akabane Akabane, Kaiga-cho, Haga-gun, Tochigi Prefecture, Kao Institute of Stock Companies (72) Inventor Yuzo Matsuo 2606 Akabane Kai-cho, Haga-gun, Tochigi, Institute of Kao Corporation (72) Inventions Person Akira Shiga 2606, Akabane, Kai-cho, Haga-gun, Tochigi Prefecture, Kao Institute of Stock Companies (72) Inventor, Junko Ishikawa 2606, Akabane, Kai-cho, Haga-gun, Tochigi Institute, Kao Corporation

Claims (6)

[Claims] 1. A magnetic recording medium having a support, a magnetic layer containing iron and nitrogen or carbon formed on the support, and a nickel layer formed on the magnetic layer. 2. The magnetic recording medium according to claim 1, wherein the magnetic layer contains iron, nitrogen and oxygen. 3. A step of forming a magnetic layer containing iron and nitrogen or carbon on a support by an ion assisted physical vapor deposition method in a vacuum atmosphere, and then forming a nickel layer on the magnetic layer by a physical vapor deposition method. The method of manufacturing a magnetic recording medium according to claim 1, wherein 4. A support, a nickel layer formed on the support, a magnetic layer containing iron and nitrogen or carbon formed on the nickel layer, and a nickel layer formed on the magnetic layer. A magnetic recording medium having: 5. The magnetic recording medium according to claim 4, wherein the magnetic layer contains iron, nitrogen and oxygen. 6. A nickel layer is formed on a support by a physical vapor deposition method in a vacuum atmosphere, then a magnetic layer containing iron and nitrogen or carbon is formed on the nickel layer by an ion assisted physical vapor deposition method, and then a physical layer is formed. The method for manufacturing a magnetic recording medium according to claim 4, further comprising a step of forming a nickel layer on the magnetic layer by a vapor deposition method.