JPH09212858A - Production of magnetic recording medium and producing device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability and corrosion resistance of a magnetic recording medium having an iron-carbon-oxygen-based magnetic layer by partially overlapping the last part of a process to form a magnetic layer and the initial part of a process to form a protective layer. SOLUTION: A gas as the carbon source such as methane is supplied to an ECR plasma CVD device 6 to produce a carbon ion, which is supplied to a sputtering region to form a Fe-C-O-based magnetic layer on a film. In this process, a gas as a carbon source is supplied from an ECR plasma CVD device 8 as a second carbon ion supply source to produce a carbon ion. A part of the carbon ion is supplied to overlap the last stage of vapor deposition of the magnetic layer (namely, the last part of the process to form the magnetic layer). Thereby, the obtd. magnetic recording medium has a mixed state of the magnetic layer and the protective layer.

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 manufacturing method and a manufacturing apparatus thereof. More specifically, iron,
The present invention relates to a method for manufacturing a metal thin film type magnetic recording medium having a magnetic layer containing carbon and oxygen, and a manufacturing apparatus used therefor.

[0002]

2. Description of the Related Art Magnetic recording media, such as magnetic tape,
A 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 dry plating methods such as vacuum deposition method, sputtering method, ion plating method and electroless plating. There is also a metal thin film type tape in which a magnetic layer made of a metal thin film containing no binder is formed on a non-magnetic support by the wet plating method. In recent years, magnetic recording has tended toward high density recording, and metal thin film type tapes are considered to be promising for high density recording because the density of the magnetic material can be increased because the magnetic layer does not contain a binder. There is.

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 are conventionally used. There is. 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. In addition, in order to increase the recording density, the relative contact speed between the tape and the head tends to increase. However, at present, satisfactory durability is not obtained for the metal thin film type magnetic layer.

Under these circumstances, Fe is the main constituent of the metal constituting the magnetic layer, which is inexpensive and does not cause environmental pollution. In order to form a magnetic layer having corrosion resistance, oxygen, nitrogen, Attempts to form a magnetic film of Fe-C-O system, Fe-N-O system, etc. by a so-called ion-assisted vapor deposition method of ionizing and irradiating gases such as carbon dioxide, methane, etc. or a mixed gas thereof. Has been.

Further, since the metal thin film type magnetic layer is formed by only adhering the metal to the support, durability and corrosion resistance are poor as they are, and a lubricant is applied for the purpose of improving the durability and corrosion resistance.
Alternatively, a non-magnetic protective layer is provided. In particular, attention has been paid to forming a carbon-based protective layer such as diamond-like carbon as the protective layer.

[0006]

However, since the magnetic layer formed by the ion assist method as described above has a sufficient durability, it is used nowadays under more severe conditions. May not be achieved. Further, even when a carbon-based protective layer such as diamond-like carbon is formed, the adhesion to the magnetic layer may be insufficient, and the desired durability improvement effect may not be obtained. Therefore, it is an object of the present invention to further improve the durability of a magnetic recording medium having a magnetic layer formed by the ion assist method.

[0007]

Means for Solving the Problems The present inventors have formed a carbon-based protective layer by a specific method on an iron-, carbon-, or oxygen-based magnetic layer formed by ion-assisted vapor deposition to obtain magnetic recording. The inventors have found that the durability of the medium is better, and have completed the present invention.

That is, the present invention comprises a step of forming a magnetic layer containing iron, carbon and oxygen as main components on a support moving in a vacuum atmosphere by an ion assisted vapor deposition method,
Then, irradiating the surface of the magnetic layer with carbon ions to form a carbon-based protective layer on the magnetic layer, in the method of manufacturing a magnetic recording medium, the end of the step of forming the magnetic layer and the formation of the protective layer. The present invention provides a method for manufacturing a magnetic recording medium, characterized in that the beginnings of the steps partially overlap.
Here, "containing iron, carbon and oxygen as the main components", does not contain any elements other than these three, or even if it contains other elements, the amount is extremely small,
It means a concentration that does not affect the intended effect of the present invention.

The present invention also provides (1) a vacuum chamber,
(2) A can roll for transporting the support, which is disposed in the vacuum chamber, and (3) a support, which is disposed below the can roll and is transported on the can roll, are made of iron. Vapor deposition means for forming a vapor deposition region, (4) first carbon ion supply means for supplying carbon ions into the vapor deposition region,
(5) Oxygen gas introduction pipe for supplying oxygen gas into the vapor deposition region, and (6) between the support transported on the can roll in the transport path of the support, rather than the deposition region of the iron. A second carbon ion supply means arranged so as to form a carbon ion irradiation area on the downstream side, wherein the second carbon ion supply means is such that the carbon ion irradiation area partially overlaps with the vapor deposition area. The present invention provides an apparatus for manufacturing a magnetic recording medium, which is arranged as described above. Hereinafter, the present invention will be described.

[Production Method of the Present Invention] In the production method of the present invention, a Fe—C—O-based magnetic layer is formed by a so-called ion-assisted deposition method in a vacuum atmosphere, and then the surface of the magnetic layer is irradiated with carbon ions. A carbon-based protective layer is formed on the magnetic layer, and the end of the magnetic layer forming step and the beginning of the protective layer forming step partially overlap. The magnetic layer and the protective layer are formed in the same vacuum.

[Production Apparatus of the Present Invention] In the present invention, the magnetic recording medium is a carbon ion supply means for ion assisted vapor deposition, a carbon ion supply means for forming a protective layer, and an oxygen gas introduction means used as necessary. It is manufactured by an apparatus including.

That is, (1) a vacuum chamber, (2) a can roll for transporting a support, which is arranged in the vacuum chamber, and (3) a can roll arranged below the can roll and above the can roll. A vapor deposition means for forming a vapor deposition area of iron between the support and the (4) first carbon ion supply means for supplying carbon ions into the vapor deposition area, (5) in the vapor deposition area Between the oxygen gas introduction pipe for supplying oxygen gas to (6) the support transported on the can roll in the transport route of the support, the carbon ion irradiation region is provided on the downstream side of the iron deposition region. And a second carbon ion supply means arranged so as to form the second carbon ion supply means, wherein the second carbon ion supply means is arranged so that the carbon ion irradiation region partially overlaps with the vapor deposition region. It is an apparatus for producing a characteristic magnetic recording medium. The first and second carbon ion supplying means are preferably ECR plasma CVD equipment.

The vapor deposition means may include an iron container (for example, a crucible) which is open to the cooling can roll, and an electron beam generator for irradiating the iron in the container with an electron beam.

According to the manufacturing apparatus of the present invention, the carbon ions for forming the Fe--C--O magnetic layer are supplied from the first carbon ion supply means, and the carbon ions are supplied from the second carbon ion supply means. Carbon ions for forming the system protective layer are supplied, but the second carbon ion supply means is such that the carbon ion irradiation area formed by the second carbon ion supply means partially overlaps with the iron vapor deposition area. Are arranged so that they overlap.

Further, the apparatus can be provided with a component conforming to a known ion-assisted vapor deposition apparatus such as a shielding plate for regulating the vapor deposition region and a roll for unwinding or winding up the support as a conveying means.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A magnetic recording medium of the present invention manufactured by the above method and apparatus comprises a support, a magnetic layer formed on the support and containing iron, carbon and oxygen as main components. In a magnetic recording medium having a carbon-based protective layer formed on the magnetic layer, the magnetic layer and the protective layer are fused via a transition region having a thickness of 30 to 50 Å where the carbon concentration gradually changes. It is characterized by that.

The magnetic recording medium of the present invention is one in which the Fe--C--O based magnetic layer and the carbon based protective layer are fused via the transition region. The magnetic recording medium of the present invention does not have a clear boundary between the magnetic layer and the carbon-based protective layer, but both layers are fused via a transition region having a thickness of 30 to 50 Å where the carbon concentration gradually changes. By this, the binding property between the magnetic layer and the carbon-based protective layer is improved, and the durability of the magnetic recording medium is further improved. In the magnetic recording medium of the present invention, first, in the transition region from the Fe—C—O-based magnetic layer to the protective film, the carbon concentration gradually increases toward the surface layer (away from the support) and approaches the surface layer. As a result, the carbon concentration becomes constant, and a thin film containing carbon as a main component can be formed, which can function as a protective layer.

The thickness of the Fe-C-O system magnetic layer is 200-10000.
Å is preferred, and more preferably 400 to 4000 Å. Further, the Fe, C 2 and O 3 concentrations (atomic%) in the magnetic layer are Fe: C
: O = 50 to 90: 3 to 40: 3 to 40. The thickness of the carbon-based protective layer is preferably 20 to 200 Å, more preferably 50 to 150 Å.

A method of manufacturing the magnetic recording medium of the present invention will be described with reference to FIG. In FIG. 1, 1 is a vacuum chamber, 2 is an unwind roll, 3 is a take-up roll, 4 is a cooling can roll, 5 is a film, 6 is a first carbon ion supply means, 7 is an oxygen introduction tube, and 8 is a second. Second carbon ion supply means, 9 is an electron gun, 10 is a crucible, and 11 is a shield plate for controlling the vapor deposition range on the film 5. The vacuum state in the vacuum chamber 1 is maintained by a vacuum system (not shown). The film 5 is wound around the winding roll 3 from the winding roll 2 through the cylindrical can roll 4. Below the can roll 4, a crucible (for example, made of MgO) 10 is placed, in which iron (for example, purity) is placed.
99.95% of Fe) is contained, and the Fe surface in the crucible 10 is irradiated with an electron beam from the electron gun 9. This allows
Heat vaporizes Fe. At the time of vapor deposition of Fe, the first carbon ion supply source 6 is arranged so that carbon ions are irradiated in a direction perpendicular to the vapor deposition surface of the film 5. In FIG. 1, an ECR plasma CVD apparatus is used as a carbon ion supply means. The ECR plasma CVD apparatus is an apparatus that applies a microwave to a source gas to plasmaize the gas and generate active species (ions, radicals) to form a thin film on an object, and can also be used as an ion gun. The ECR plasma CVD
A gas serving as a carbon source, such as methane, is supplied to the device 6 to generate carbon ions and the carbon ions are supplied to the vapor deposition region, and oxygen gas is supplied from the oxygen gas introducing pipe 7 to the vapor deposition region,
An Fe-C-O magnetic layer is formed on the film. that time,
ECR plasma CVD equipment 8 which is the second carbon ion source
In the same manner as described above, a gas serving as a carbon source is supplied to generate carbon ions, and a part of the carbon ions is partially overlapped with the end of the deposition region of the magnetic layer (that is, the end of the magnetic layer forming step). To supply. As a result, a magnetic recording medium in which the magnetic layer and the protective layer, which are the features of the present invention, are fused is obtained.

The material for the support includes 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; polyimides; aromatic polyamides. Etc. plastic etc. are used. The thickness of these substrates is 3-50 μm
It is a degree.

On the carbon-based protective layer, it is preferable to form a lubricating layer having a thickness of about 2 to 50Å, particularly a lubricating layer made of a fluorine-based lubricant such as perfluoropolyether, on the surface on which the magnetic layer is formed. A back coat layer containing carbon black as a main component and having a thickness of about 0.1 to 1.0 μm may be further provided on the opposite surface. As a raw material for forming these layers, conventionally known materials can be appropriately used. Also, the back coat layer is
It may be formed by evaporating a metal such as a Cu-Al alloy.

[0022]

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 An Fe—C—O magnetic layer was formed on a PET film, and a carbon protective layer, a lubricating layer and a back coat layer were further formed,
A magnetic film was produced. The conditions for forming each layer are as follows. The PET film 5 having a thickness of 6 μm is set in the ion assisted oblique vapor deposition apparatus shown in FIG. 1, and the electron gun 8 is operated while traveling at a speed of 2 m / min (output 30 kW).
Iron in the crucible 10 is evaporated, iron particles are vapor-deposited on the PET film 5, and 400 W, 2.45 GHz microwave is introduced into the ECR plasma CVD apparatus 6 having a magnetic field of 875 G inside, and the apparatus 6 Methane gas is supplied to (flow rate 40SCC
M), carbon ions are generated toward the iron vapor deposition region of the PET film 5, and the carbon gas is irradiated to the iron vapor deposition region through the oxygen gas introducing pipe 7 (flow rate 20 SCCM). In addition, a microwave of 600 W and 2.45 GHz was introduced into the ECR plasma CVD apparatus 8 having a magnetic field of 875 G inside, and benzene was supplied to the apparatus 8 (flow rate 15 SCCM) to generate carbon ions, and an iron deposition area was formed. Was irradiated so that a part of the carbon ions was supplied to the end portion (end of the magnetic layer forming step). In this way, a thin film was formed in which the Fe-C-O-based magnetic layer and the carbon-based protective layer were fused via the transition region.

Then, perfluoropolyether (FOMBL
IN Z DOL, made by Montecatini Co.) as a fluorine-based inert liquid (Fluorinert FC-77, made by Sumitomo 3M Limited)
The coating material diluted and dispersed so as to be 0.05% by weight was applied onto the protective layer by a die coating method so that the dry film thickness was 15Å, and dried at 105 ° C to form a lubricating layer. Also, on the surface opposite to the magnetic layer surface of the PET film, a back coat paint made by dispersing carbon black with an average particle size of 10 to 20 nm in a binder resin of urethane prepolymer and vinyl chloride resin is applied. A back coat layer was formed by coating so as to have a dry film thickness of 0.5 μm by a coating method and drying. From the above, Fe-C-
The film on which the O 2 magnetic layer, the protective layer, the lubricant layer and the back coat layer were formed was cut to a width of 8 mm and loaded into an 8 mm VTR cassette case to obtain an 8 mm video tape.

(2) Performance Evaluation The still durability and corrosion resistance of the 8 mm video tape obtained above were evaluated by the following methods. Table 1 shows the results. Table 2 shows the film thickness (total thickness on the base film), coercive force and saturation magnetic flux density of the magnetic tape. Still durability Still durability is a modification of the commercially available high band 8mm VTR.
The output (dB) was compared when the 10 MHz output was compared before and after performing the test still playback mode for 10 hours. Corrosion resistance Corrosion resistance is the deterioration rate (%) of saturation magnetic flux density (Bs) after storing 8 mm video tape for 1 week at 60 ° C and 90% RH.
Was evaluated.

Comparative Example 1 ECR which is the second carbon ion supply means in Example 1
An Fe-C-O-based magnetic layer was formed on the PET film in the same manner as in Example 1 without operating the plasma CVD apparatus 8. Then, on this magnetic layer, a microwave of 600 W and 2.45 GHz was introduced into the ECR plasma CVD apparatus (internal magnetic field 875 G) 8'of FIG. 2 and benzene was supplied to the apparatus (flow rate 15 SCC).
M), carbon ions were generated, and a carbon-based protective layer was formed on the magnetic layer. Otherwise, a magnetic film was produced in the same manner as in Example 1, and the same evaluation as in Example 1 was performed. Table 1 shows the results. Table 2 shows the film thickness (total thickness on the base film), coercive force and saturation magnetic flux density of the magnetic tape.

[0027]

[Table 1]

[0028]

[Table 2]

From the above results, although the magnetic tape of Example 1 and the magnetic tape of Comparative Example 1 have almost the same magnetic characteristics,
It can be seen that in Example 1, durability and corrosion resistance are further improved.

[0030]

According to the present invention, the durability and corrosion resistance of a magnetic recording medium having an iron-carbon-oxygen type magnetic layer are improved.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an apparatus for manufacturing a magnetic recording medium of the present invention.

[Figure 2] Schematic diagram showing an example of ECR plasma CVD equipment

[Explanation of symbols]

 1 vacuum chamber 5 support 6 first ECR plasma CVD apparatus 7 oxygen gas introduction tube 8 second ECR plasma CVD apparatus

Claims (4)

[Claims] 1. A step of forming a magnetic layer containing iron, carbon and oxygen as main components by an ion assisted vapor deposition method on a support moving in a vacuum atmosphere, and then irradiating the surface of the magnetic layer with carbon ions. And the step of forming a carbon-based protective layer on the magnetic layer, the end of the step of forming the magnetic layer and the beginning of the step of forming the protective layer partially overlap. A method for manufacturing a characteristic magnetic recording medium. 2. A vacuum chamber; (2) A can roll for transporting a support, which is arranged in the vacuum chamber.
(3) a vapor deposition means disposed below the can roll to form a vapor deposition region of iron between the can roll and a support conveyed on the can roll; and (4) supplying carbon ions into the vapor deposition region. Of the first carbon ion supply means, (5) an oxygen gas introducing pipe for supplying oxygen gas into the vapor deposition region, and (6) a support transported on the can roll in a transport path of the support. In between, and having a second carbon ion supply means arranged to form a carbon ion irradiation region on the downstream side of the iron deposition region, the second carbon ion supply means, the carbon ion irradiation An apparatus for manufacturing a magnetic recording medium, wherein an area is arranged so as to partially overlap with the vapor deposition area. 3. The manufacturing apparatus according to claim 2, wherein the first and second carbon ion supply means are ECR plasma CVD apparatuses. 4. The vapor deposition means includes an iron container open to the cooling can roll, and an electron beam generator for irradiating the iron in the container with an electron beam. 3. The manufacturing apparatus described in 3.