JPH0845052A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve sliding durability by successively forming a magnetic layer made of a metallic magnetic thin film, a protective film of silicon dioxide and a lubricating layer of a fluorine-contg. hydrocarbon lubricant on a nonmagnetic substrate. CONSTITUTION:A magnetic layer made of a metallic magnetic thin film is formed on a tape-shaped nonmagnetic substrate. A protective film of silicon dioxide is formed on the magnetic layer by a thin film forming means such as vapor deposition or ion plating. A lubricating layer of a fluorine-contg. hydrocarbon lubricant such as perfluoro-polyether is further formed on the protective film. Even when this method is applied to the production of a magnetic tape, the resultant magnetic recording medium has satisfactory sliding durability.

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 suitable for being applied to a magnetic tape, and more particularly to a magnetic recording medium having improved sliding durability.

[0002]

2. Description of the Related Art Conventionally, as a magnetic recording medium, a powder magnetic material such as oxide magnetic powder or alloy magnetic powder is used as a vinyl chloride-vinyl acetate copolymer, polyester resin,
A coating-type magnetic recording medium prepared by coating a non-magnetic support with a magnetic coating material dispersed in an organic binder such as urethane resin or polyurethane resin and drying it is widely used.

On the other hand, with the increasing demand for high-density magnetic recording, Co--Ni alloys, Co--Cr alloys, Co
A metallic magnetic material such as —O is coated with a polyester film or polyamide by plating or a vacuum thin film forming means (vacuum deposition method, sputtering method, ion plating method, etc.).
A so-called metal magnetic thin film type magnetic recording medium, which is directly deposited as a magnetic layer on a non-magnetic support such as a polyimide film, has been proposed and attracted attention.

This metal magnetic thin film type magnetic recording medium is excellent not only in coercive force and squareness ratio but also in electromagnetic conversion characteristics at short wavelengths, and since the thickness of the magnetic layer can be made extremely thin, recording demagnetization and reproduction are required. Has a number of advantages such as a significantly small thickness loss and the fact that it is not necessary to mix a binder which is a non-magnetic material in the magnetic layer, so that the packing density of the magnetic material can be increased. That is, it is considered that the metal magnetic thin film type magnetic recording medium is the mainstream of magnetic recording media compatible with high density magnetic recording because of its superior magnetic characteristics.

In order to improve the electromagnetic conversion characteristics of this type of magnetic recording medium and to obtain a larger output, the magnetic layer is obliquely deposited when forming the magnetic layer of the magnetic recording medium. A magnetic recording medium that has been subjected to so-called oblique vapor deposition has been proposed and put into practical use.

[0006]

By the way, it is expected that a higher recording density will be required in the future. Therefore, the above magnetic recording medium tends to be smoothed to reduce spacing loss. However, with the smoothing of the magnetic recording medium, the frictional force between the magnetic head and the magnetic recording medium increases, the shear stress generated in the magnetic recording medium increases, and improvement in sliding durability is required.

Among the above magnetic recording media, in a magnetic disk such as a hard disk, a flying type magnetic head for recording / reproducing at a minute distance from the magnetic disk is often used as a magnetic head. Since the contact time with the magnetic disk is comparatively short, the improvement in sliding durability is practical even if the improvement is relatively small.

However, in the magnetic tape of the magnetic recording medium, the magnetic head is in contact with the magnetic tape during any of the fast-forwarding and rewinding operations in addition to recording / reproducing, and the sliding durability thereof is greatly improved. Is required to

Therefore, in such a magnetic recording medium, it has been studied to form a protective film on the magnetic layer in order to improve sliding durability. The protective film may be a carbon film, a silicon dioxide film, a zirconia film, or the like. However, it is difficult to greatly improve the sliding durability by simply forming a protective film on the surface of the magnetic layer.

Therefore, the present invention has been proposed in view of the conventional circumstances, and an object thereof is to provide a magnetic recording medium which is greatly improved in sliding durability and which is particularly suitable for a magnetic tape. And

[0011]

In order to achieve the above-mentioned object, a magnetic recording medium of the present invention has a magnetic layer made of a metal magnetic thin film formed on a non-magnetic support, and the magnetic layer is made of silicon dioxide. Is formed, and a lubricating layer made of a hydrocarbon lubricant containing fluorine is further formed on the protective film.

Examples of the above-mentioned fluorine-containing hydrocarbon lubricants include perfluoropolyether and the like. To form a lubricating layer, the above lubricants are applied to form a coating film. The method of forming may be mentioned.

In the magnetic recording medium of the present invention,
It is suitable to be applied to a magnetic tape using a tape-shaped support as a non-magnetic support.

By the way, as a method for forming the protective film of the magnetic recording medium as described above, thin film forming means such as a vapor deposition method, an ion plating method, a sputtering method and a CVD method can be mentioned.

The vapor deposition method is a technique for forming a thin film by heating and evaporating a thin film forming material to deposit evaporated particles on a substrate. Examples of the method of heating and evaporating include resistance heating, high frequency heating, flash heating, electron beam heating and the like. Reactive vapor deposition is also possible by introducing a gas during vapor deposition to react with vapor deposited particles.

In the ion plating method, the thin film forming material or its component metal is heated in a low vacuum containing an inert gas such as argon or an active gas such as oxygen or nitrogen by resistance heating, high frequency heating or heating by electron impact. Evaporate to
It is a technique for forming a thin film by ionizing by DC discharge, RF discharge, electron impact, etc. and accelerating by an electric field, and as it is or by reacting with an atmosphere active gas to deposit it on a substrate.

In the sputtering method, an inert gas such as argon is ionized (plasmaized) by utilizing an electric field or a magnetic field to accelerate the ionized argon ions, and the kinetic energy of the target is used to form a target made of a thin film forming material. This is a technique for forming a thin film by ejecting atoms from the substrate and depositing the ejected atoms on the substrate. In particular, the RF sputtering method using an alternating electric field can form many kinds of thin films because both a metallic material and a non-metallic material can be used as a target material.

Further, in the CVD method, the energy of plasma generated by using an electric field or a magnetic field is used to cause a chemical reaction such as decomposition / bonding on the vaporized raw material in the vapor phase or on the substrate surface to form a thin film. It is a technology. Especially recently
Studies have also been made to form a diamond-like carbon (DLC) film, which is a harder carbon film, by the above CVD method.

Among the above-mentioned thin film forming means, the sputtering method and the CVD method have a disadvantage that the thin film forming speed is slower than the vapor deposition method and the ion plating method, and the productivity is not good. From this point of view, it is preferable to use a vapor deposition method or an ion plating method as the protective film forming means.

[0020]

In the magnetic recording medium of the present invention, a magnetic layer formed of a metal magnetic thin film is formed on a non-magnetic support, a protective film made of silicon dioxide is formed on the magnetic layer, and fluorine is formed on the protective film. Since the lubricating layer made of the contained hydrocarbon lubricant is formed, it has sufficient sliding durability even when applied to a magnetic tape.

[0021]

EXAMPLES Specific examples to which the present invention is applied will be described below based on experimental results. In this experimental example, a magnetic tape was used as a magnetic recording medium, and a protective film made of silicon dioxide of the magnetic tape was formed by a vapor deposition method, an ion plating method, a sputtering method, and a hydrocarbon containing fluorine was formed thereon. A magnetic tape sample was manufactured by forming a lubricating layer made of a system lubricant, and the sliding durability of these magnetic tape samples was evaluated.

First, the vacuum vapor deposition apparatus used in this experimental example will be described with reference to the drawings. As shown in FIG. 1, this vacuum vapor deposition apparatus has delivery rolls 2 and take-up rolls 3 arranged on the upper and left sides of a vacuum chamber 1 whose inside is in a vacuum state, and a can roll 4 in the center of the vacuum chamber 1. Are arranged. It should be noted that exhaust ports 5a and 5b are provided above and below the vacuum chamber 1, and the interior of the vacuum chamber 1 is brought into a vacuum state by exhausting from there. Further, a guide roll 6 is arranged between the delivery roll 2 and the can roll 4, and a guide roll 7 is arranged between the can roll 4 and the winding roll 3.

The can roll 4 is the delivery roll 2
The flexible continuous substrate 8 wound around the substrate is provided so as to be pulled out downward in the figure, and is provided with a feeding roll 2 and a winding roll 3.
It is made larger than the diameter of. The delivery roll 2, the winding roll 3 and the can roll 4 each have a cylindrical shape having a width substantially the same as that of the flexible continuous substrate 8, and the can roll 4 has a cooling device (not shown) inside. Is provided so that the deformation of the flexible continuous substrate 8 due to the temperature rise can be suppressed.

The guide rolls 6 and 7 are arranged between the feed roll 2 and the can roll 4 and between the can roll 4 and the take-up roll 3, respectively, and are provided above the can roll 4 in the figure. ing. That is, the guide rolls 6 and 7 are from the delivery roll 2 to the can roll 4
Is applied to the flexible continuous substrate 8 wound on the take-up roll 3 from the can roll 4 by applying a predetermined tension so that the flexible continuous substrate 8 reliably travels on the peripheral surface of the can roll 4. It is something to do.

Below the can roll 4, a crucible 9 is provided.
The crucible 9 is filled with a thin film forming material (not shown). The can roll 4 is located between the can roll 4 and the crucible 9 filled with the thin film forming material.
In the vicinity of, the shutter 10 is provided so as to be curved so as to face the peripheral surface of the can roll 4.

Further, an electron gun 11 is provided on the side wall portion outside the vacuum chamber 1. The electron gun 11 is the electron gun 1.
The thin film forming material filled in the crucible 9 is swept and irradiated with the electron beam X irradiated by the electron beam X in the figure, and the thin film forming material is irradiated by the electron beam X. Is capable of being heated and evaporated.

A gas introducing pipe 12 is arranged between the crucible 9 and the shutter 10, and a gas can be introduced through the gas introducing pipe 12 during vapor deposition.
The so-called reactive vapor deposition is possible, in which a thin film forming material that has been heated and vaporized reacts with a gas for vapor deposition.

In the vacuum vapor deposition apparatus constructed as described above, the flexible continuous substrate 8 wound around the delivery roll 2 is rotated from the delivery roll 2 which rotates at a constant speed in the clockwise direction, for example, by the arrow M _{1 in the} figure. And is supplied to the can roll 4 that rotates at a constant speed in the clockwise direction, for example, while receiving a predetermined tension from the guide roll 6. After that, the flexible continuous substrate 8 is pulled upward from the can roll 4 while receiving a predetermined tension by the guide roll 7, and is wound on the winding roll 3 rotating at a constant speed in the clockwise direction, for example, in the direction of the arrow M ₁ in the drawing. It is run and wound up.

The flexible continuous substrate 8 is vapor-deposited when passing through the peripheral surface of the can roll 4.

That is, in the vacuum chamber of FIG. 1, a crucible 9 filled with a thin film forming material is provided below the can roll 4 as described above, and the crucible 9 has the same width as the can roll 4. It consists of the width of. And
The thin film forming material with which the crucible 9 is filled is heated and evaporated by the electron beam X emitted from the electron gun 11 provided outside the vacuum chamber 1. At this time, the gas is introduced into the vacuum chamber from the gas introduction pipe 12. Therefore, the thin film forming material evaporated by the electron beam X reacts with the gas and then adheres to the flexible continuous substrate 8 traveling at a constant speed on the peripheral surface of the can roll 4 to form a film. It

At this time, since the shutter 10 is arranged so as to cover a predetermined area of the can roll 4, the thin film forming material is vapor-deposited within a predetermined angle range.

Next, the ion plating apparatus used in this experimental example will be described with reference to the drawings. This ion plating device has a configuration similar to that of the above-described vacuum vapor deposition device. That is, the delivery roll 22, the take-up roll 23, and the can roll 24 are disposed in the vacuum chamber 21 in which the exhaust ports 25a and 25b are arranged at the top and bottom and the inside is in a vacuum state. Guide rolls 26 and 27 are arranged between the take-up rolls 23, respectively. Then, the feed roll 22, the guide roll 26, the can roll 24, the guide roll 27, and the winding roll 23.
The flexible continuous substrate 28 is sequentially run on the above in the direction shown by arrow M ₂ .

A crucible 29 filled with a thin film forming material (not shown) is provided below the can roll 24.
In the vicinity of the can roll 24 between the can roll 24 and the crucible 29, a curved shutter 30 is disposed so as to face the peripheral surface of the can roll 24.

Further, an electron gun 31 is provided on the side wall portion outside the vacuum chamber 21. A gas introduction pipe 32 is arranged between the crucible 29 and the shutter 30.

The shape and role of each of these constituent members are the same as those of the above-described vacuum vapor deposition apparatus.

In this ion plating apparatus, a coil 33 is provided between the crucible 29 filled with the thin film forming material and the shutter 30, and the coil 33 is provided with a high frequency power source 34 via a matching unit 35. It is connected.

When a high frequency (for example, 13.56 MHz) is introduced from the high frequency power source 34 to the coil 33 through the matching device 35, when the gas is introduced from the gas introduction pipe 32, the gas is excited and turned into plasma. . That is,
The thin film forming material heated and evaporated by the electron beam X shown by the broken line in the figure of the electron gun 31 passes through the plasma, and a part of the vapor of the thin film forming material is ionized and the peripheral surface of the can roll 24 is Flexible continuous substrate 28 that runs at a constant speed
Deposited on top and deposited as a film. A DC bias voltage is applied to the flexible continuous substrate 28 running on the can roll 24 from a bias electrode 36 connected to a DC power supply 37.

Next, the sputtering apparatus used in this experimental example will be described with reference to the drawings. This sputtering apparatus has a configuration substantially similar to that of the vacuum vapor deposition apparatus described above. That is, the exhaust port 45
Vacuum chamber 4 in which a and 45b are arranged and the inside is in a vacuum state
A delivery roll 42, a take-up roll 43, and a can roll 44 are arranged in the unit 1, and guide rolls 46 and 47 are provided between the delivery roll 42, the can roll 44, and the take-up roll 43, respectively. Then, the delivery roll 42, the guide roll 46, the can roll 4
4, the flexible continuous substrate 48 is sequentially run on the guide roll 47 and the winding roll 43 in the direction shown by an arrow M ₃ in the figure.

The shape and role of each of these constituent members are the same as those of the above-described vacuum vapor deposition apparatus.

In the sputtering apparatus, a sputter electrode 49 is provided below the can roll 44, a target 51 made of a thin film forming material is arranged on the sputter electrode 49, and a high frequency wave is passed through a matching unit 55. The power supply 54 is connected. In the vicinity of the can roll 44 between the can roll 44 and the sputter electrode 49, a curved shutter 50 is disposed so as to face the peripheral surface of the can roll 44. further,
A gas introduction pipe 52 for introducing gas is arranged between the sputtering electrode 49 and the shutter 50.

Therefore, if the target 51 is sputtered by the gas introduced from the gas introduction pipe 52, the flexible continuous substrate 4 traveling at a constant speed on the peripheral surface of the can roll 44.
A thin film forming material is deposited on the film 8 to form a film.

A magnetic tape sample was formed by using the above apparatus to form a magnetic layer of a magnetic tape, a protective film made of silicon dioxide, and a lubricating layer made of a hydrocarbon lubricant containing fluorine. Was manufactured.

The above magnetic tape sample was manufactured as follows. That is, first, using the vacuum vapor deposition apparatus shown in FIG. 1, a tape-shaped non-magnetic support made of polyethylene terephthalate (PET) was used as the flexible continuous substrate 8, and a Co—Ni—O metal magnetic thin film was formed thereon. To form a magnetic layer.

The metal magnetic thin film is formed by reactive vapor deposition with an electron gun power of 30 kW, a vacuum degree of 2 × 10 ^-2 Pa, a thin film forming material of Co-Ni, and an introduction gas of oxygen gas. The film thickness was 200 nm.

Next, a protective film made of silicon dioxide is formed on each magnetic layer made of the metal magnetic thin film by using each device, and then a lubricating layer made of a hydrocarbon lubricant containing fluorine is formed. A magnetic tape sample was obtained. That is, a tape-shaped non-magnetic support having a magnetic layer formed thereon is used as the flexible continuous substrate 8, 28, 48 of each device, a protective film is formed on the tape-shaped non-magnetic support, and then a fluorine-containing hydrocarbon-based support A lubricant was applied to form a lubricating layer, and a magnetic tape sample was manufactured.

When the protective film is formed by a vacuum vapor deposition apparatus, the electron gun power is 5 kW and the degree of vacuum is 2 × 1.
0 ^-2 and Pa, the film materials and Si, introduced gas and oxygen gas, is formed by reactive deposition, 10 nm thickness
Formed as. Then, a perfluoropolyether as a hydrocarbon lubricant containing fluorine was applied on the protective film to form a lubricating layer, and the manufactured magnetic tape sample was used as Example 1.

When the protective film is formed by an ion plating apparatus, the electron gun power is 6 kW, the degree of vacuum is 2 × 10 ^-2 Pa, the thin film forming material is Si,
Introduced gas is oxygen gas, high frequency power is 100W,
DC bias voltage is -100V, protective film thickness is 10n
formed as m. Then, perfluoropolyether as a hydrocarbon lubricant containing fluorine was applied onto the protective film to form a lubricating layer, and the manufactured magnetic tape sample was used as Example 2.

When the protective film is formed by a sputtering apparatus, the degree of vacuum is 4.6 × 10 ^-1 Pa, the target is SiO ₂ , the sputter gas is argon gas, the high frequency power is 300 W, and the protective film is Thickness 10 nm
Formed as. Then, perfluoropolyether was applied as a fluorine-containing hydrocarbon lubricant on the protective film to form a lubricant layer, and the manufactured magnetic tape sample was used as Example 3.

Further, for comparison, Examples 1 to 3 above are used.
After forming a protective film in the same manner as above, magnetic tape samples without a lubricating layer were also manufactured, and each was set as Comparative Examples 1 to 3.

Then, the above Examples 1 to 3 and Comparative Examples 1 to 1
The sliding durability of the magnetic tape sample of No. 3 was evaluated.

As for the sliding durability of the magnetic tape sample, a modified 8 mm video deck CVD-1000 (model name) manufactured by Sony Corporation was used, and the output was 3 d more than the initial output.
The number of times the magnetic head slid (the number of passes) when B was lowered was measured and evaluated. The results are shown in Table 1.

[0052]

[Table 1]

From the results shown in Table 1, a magnetic layer made of a metal magnetic thin film is formed on a non-magnetic support, a protective film made of silicon dioxide is formed on the magnetic layer, and fluorine is contained on the protective film. It was confirmed that in Examples 1 to 3 in which the lubricating layer made of a hydrocarbon-based lubricant was formed, the sliding durability was significantly improved.

Further, when the protective film made of silicon dioxide is formed by vapor-depositing silicon in an oxygen atmosphere as in Example 1, the productivity becomes good.

[0055]

As is apparent from the above description, in the magnetic recording medium of the present invention, a magnetic layer made of a metal magnetic thin film is formed on a non-magnetic support, and a protective layer made of silicon dioxide is formed on the magnetic layer. Since a film is formed and a lubricating layer made of a hydrocarbon-based lubricant containing fluorine is formed on the protective film, it has sufficient sliding durability even when applied to a magnetic tape, It has high reliability.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example of a vacuum vapor deposition device.

FIG. 2 is a schematic diagram showing a configuration example of an ion plating device.

FIG. 3 is a schematic diagram showing a configuration example of a sputtering apparatus.

[Explanation of symbols]

 1,21,41 Vacuum chamber 2,22,42 Sending roll 3,23,43 Winding roll 4,24,44 Can roll 8,28,48 Flexible continuous substrate 9,29 Crucible 11,31 Electron gun 12, 32,52 Gas introduction tube 33 Coil 34,54 High frequency power supply 35,55 Matching device 49 Sputtering electrode 51 Target X electron beam

Claims (2)

[Claims] 1. A magnetic layer formed of a metal magnetic thin film is formed on a non-magnetic support, a protective film made of silicon dioxide is formed on the magnetic layer, and a hydrocarbon-based hydrocarbon-based material is further formed on the protective film. A magnetic recording medium having a lubricating layer formed of the above lubricant. 2. The magnetic recording medium according to claim 1, wherein the non-magnetic support is a tape-shaped support.