JPH0836749A - Manufacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a magnetic recording medium which can continuously form a film by vacuum evaporation even in the case of using a sublimated material to enhance productivity. CONSTITUTION:When a thin film comprising an evaporated material 16 is formed on a base body by vacuum evaporation, the evaporated material 16 is filled into a container 12, the inside of which is formed into a recessed form. and the evaporation is performed while the container 1 is being rotated. For the evaporated material 16, a granular sublimated material can be used, and it is preferable that the size of the particle is not less than 1mm and not more than 1/3 of the depth of the container.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium in which a film is formed by vacuum evaporation using a sublimable substance as an evaporation material, and particularly, a method for manufacturing a magnetic recording medium suitable for forming a protective film. Regarding

[0002]

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

On the other hand, with the increasing demand for high-density magnetic recording, Co--Ni alloys, Co--Cr alloys, C
On a non-magnetic support made of a polyester film, a polyamide film, a polyimide film, or the like by plating a metal magnetic material made of an alloy such as an OO alloy or by a vacuum thin film forming technique (vacuum deposition method, sputtering method, ion plating method, etc.) A magnetic recording medium of a so-called metal magnetic thin film type, in which a magnetic layer is formed by directly adhering the magnetic recording medium to a magnetic recording medium, 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 in a short wavelength range, and since the magnetic layer can be extremely thin, recording demagnetization and reproduction are possible. There are many advantages such as a significantly small thickness loss at the time, 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. Therefore, it is considered that such a metal magnetic thin film type magnetic recording medium will become the mainstream in the field of high density magnetic recording in the future because of its superior magnetic characteristics.

In such a metal magnetic thin film type magnetic recording medium, in order to improve electromagnetic conversion characteristics and achieve higher output, a magnetic material is used as a non-magnetic support when forming a magnetic layer of the magnetic recording medium. A so-called oblique vapor deposition method is adopted in which vapor deposition is performed obliquely to the surface of the.

In such a magnetic recording medium, if the track density and the recording density of the magnetic recording medium are increased as the recording density is further increased, the spacing loss becomes large. Moreover, the surface of the magnetic recording medium tends to be smoothed.

However, when the surface of the magnetic recording medium is smoothed, the magnetic head and the medium are attracted to each other to increase the frictional force and the shearing stress generated in the medium becomes large. As a result, the magnetic recording medium is seriously damaged and the sliding durability is deteriorated.

Therefore, a method of forming a protective film on the surface of the magnetic layer has been proposed in order to ensure good still characteristics.

As the protective film, for example, a carbon film, a quartz (SiO ₂ ) film, a zirconia (ZrO ₂ ) film and the like have been studied, and some hard disks have already been put into practical use and produced.

As a method for forming these protective films,
A sputtering method, a CVD method or the like is used.

The above sputtering method uses an electric field or a magnetic field to ionize (plasma) an inert gas such as Ar gas, then accelerates the ionized Ar ions, and the kinetic energy of the ions accelerates the target atoms. It is a physical process in which a target film is formed by ejecting the atoms and depositing the ejected atoms on a substrate oppositely arranged. In particular, in the RF sputtering method using an alternating electric field, since a metal or a non-metal solid substance can be used as a target material, many kinds of films can be formed.

On the other hand, the CVD method is a chemical process in which the energy of plasma generated using an electric field or a magnetic field is used to cause a chemical reaction in a gas as a raw material to form a film. In particular, recently, in the technique of forming a carbon film by the above CVD method, formation of a diamond-like carbon (DLC) film, which is a harder film, has been developed.

[0013]

However, these methods of forming a protective film by the sputtering method or the CVD method have a film forming rate higher than that of the coating method or the vacuum evaporation method used when forming the magnetic layer. It is slow and extremely inefficient in terms of productivity.

That is, in the above vacuum vapor deposition method, the metal heated by electron beam, resistance heating, induction heating, etc. is melted and becomes a liquid phase, so that a metal material in the form of small pellets is supplied to this melt. By this, the above-mentioned melt can be kept constant, and further continuous vapor deposition becomes possible.

On the other hand, when a sublimable material is used as the evaporation source, it is impossible to continuously evaporate the material in an amount larger than the amount of the material initially charged. This is because these materials are hard to evaporate by resistance heating or induction heating, and the heating means is limited to electron beam heating. In the electron beam heating, the sublimable material evaporates only in the portion irradiated with the electron beam, and it is difficult to supply the material only to that portion. Also, refractory materials are essentially unsuitable for vacuum deposition.

In general, carbon or quartz used as a protective film material has a subliming property, and zirconia has a high melting property. Therefore, a vacuum deposition method is used as a protective film forming method. Although it is not used and is disadvantageous in terms of productivity, the reality is that the sputtering method or the CVD method is adopted.

Therefore, the present invention has been proposed for the purpose of solving this problem, and even when a sublimable material is used, it is possible to continuously form a film by vacuum vapor deposition, thereby improving productivity. It is an object of the present invention to provide a method for manufacturing a magnetic recording medium capable of improving the above.

[0018]

A method of manufacturing a magnetic recording medium according to the present invention is proposed to achieve the above-mentioned object.

That is, when a thin film made of an evaporation material is formed on a substrate by vacuum evaporation, the evaporation material is filled in a container having a concave inside, and evaporation is performed while rotating the container. It is what

According to the method of manufacturing a magnetic recording medium of the present invention, a magnetic magnetic thin film made of a ferromagnetic metal material is formed on a non-magnetic support by vacuum deposition to prepare a magnetic recording medium original fabric,
A magnetic tape is obtained by cutting this into a predetermined size.

As the ferromagnetic metal material used here, any material can be used as long as it is used for a usual vapor deposition tape.

For example, ferromagnetic metals such as Fe, Co and Ni, Fe-Co, Co-Ni and Co-Ni-P.
t, Fe-Co-Ni, Fe-Cu, Co-Cu, Co
-Au, Co-Pt, Mn-Bi, Mn-Al, Fe-
Cr, Ni-Cr, Fe-Co-Cr, Fe-Ni-
B, Fe-Co-B, Co-Ni-Cr, Fe-Co-
Examples include in-plane magnetization recording ferromagnetic alloys such as Ni-Cr and Fe-Co-Ni-B, and perpendicular magnetization recording ferromagnetic alloys such as Co-Cr and Co-O.

In particular, when an in-plane magnetization recording ferromagnetic alloy is used, Bi, Sb, Pb, S are previously formed on the non-magnetic support.
A base film made of a low melting point non-magnetic material such as n, Ga, In, Si, or Ti is formed in advance, and the ferromagnetic metal material is vapor-deposited or sputtered from the vertical direction to form a low melting point magnetic material in the metal magnetic thin film. The material may be diffused to eliminate the orientation to secure the in-plane isotropic property and improve the coercive force.

The magnetic layer may be a single layer film of a metal magnetic thin film made of these ferromagnetic metal materials or a multi-layer film. Further, an underlayer or an intermediate layer may be provided between the non-magnetic support and the metal magnetic thin film, or in the case of a multi-layer film, to improve the adhesive force between the layers and control the coercive force. Further, for example, the vicinity of the surface of the magnetic layer may be an oxide for improving the corrosion resistance.

Further, it is desirable to form a protective film on the surface of the magnetic layer in order to improve wear resistance and sliding durability.

The protective film material may be any material as long as it is generally used as a protective film material in this type of magnetic recording medium, and examples thereof include carbon, Al ₂ O ₃ and SiO. ₂ , Si ₃ N ₄ , S
iC, TiC, TiN, etc. are mentioned. In particular, the present invention is suitable for substances such as carbon and SiO ₂ which are sublimable materials. The protective film may be a single layer film of these, a multilayer film or a composite film.

Of course, the structure of the magnetic recording medium is not limited to this, and may be changed without departing from the scope of the present invention, for example, a back coat layer may be formed if necessary, or a non-magnetic support may be formed. It does not matter that an undercoat layer is formed on the surface or various functional layers such as a lubricant layer and a rust preventive layer are formed. In this case, as the material contained in the non-magnetic pigment, the resin binder, or the lubricant layer or the rust preventive layer contained in the back coat layer, any conventionally known material can be used.

The non-magnetic support is not particularly limited as long as it is a material usually used in this kind of magnetic recording medium, and if specifically exemplified, polyesters,
Polyolefins, cellulose derivatives, vinyl resins,
Any polymer support formed of a polymer material represented by polyimides, polyamides, polycarbonates and the like can be used.

In the present invention, the evaporation material is a particulate sublimable substance, and the size of the particles is preferably 1 mm or more and 1/3 or less of the depth of the container. If the size of the particles is smaller than 1 mm, the particles are likely to be scattered when the vacuum chamber is evacuated. On the contrary, if the size is larger than 1/3 of the depth of the container, it becomes difficult to fill the container. However, there is a possibility that rotation failure may occur when the container is rotated.

An electron gun can be used as a means for heating the evaporation material, and an electron beam emitted from the electron gun can be irradiated on the upper surface of the evaporation material while operating in the radial direction. preferable. As a result, the evaporation material is uniformly evaporated, and vapor deposition is effectively performed.

[0031]

By filling the evaporation material in a container having a concave inside and performing vapor deposition while rotating the container, even if the evaporation material has sublimability or is a high melting point material, The evaporation amount is kept constant, and a thin film made of the evaporation material can be continuously formed on the substrate by vapor deposition.

[0032]

EXAMPLES Specific examples to which the present invention is applied will be described in detail below with reference to the drawings and experimental results.

First, the structure of the vacuum vapor deposition apparatus used in this embodiment will be described.

As shown in FIG. 1, in this vacuum vapor deposition apparatus, exhaust ports 1a provided at the head and the bottom, respectively.
In the vacuum chamber (vapor deposition apparatus main body) 1 that is evacuated from 1b and has a vacuum inside, a feed roll 3 that rotates at a constant speed in the clockwise direction in the figure, and a winding roller that rotates at a constant speed in the clockwise direction in the figure. The roll 4 and the feed roll 3 are provided.
The tape-shaped base film 2 is sequentially run from the to the winding roll 4.

A cooling can 5 having a diameter larger than that of each of the rolls 3 and 4 is provided in the middle of the traveling of the base film 2 from the feed roll 3 to the winding roll 4 side.
Is provided.

The cooling can 5 is provided so as to pull out the base film 2 downward in FIG. 1, and is configured to rotate at a constant speed in the clockwise direction in the drawing. Further, a cooling device (not shown) is provided inside the cooling can 5 so as to suppress deformation of the base film 2 due to temperature rise.

Incidentally, the feed roll 3 and the winding roll 4 described above.
Each of the cooling cans 5 has a cylindrical shape having a length substantially the same as the width of the base film 2.

Therefore, the base film 2 is sequentially fed from the feed roll 3, moved and run along the peripheral surface of the cooling can 5, and further wound on the winding roll 4 in sequence. ing.

It should be noted that small-diameter guide rolls 6 and 7 are provided between the feed roll 3 and the cooling can 5 and between the cooling can 5 and the take-up roll 4, respectively. When 2 travels from the feed roll 3 to the cooling can 5 and from the cooling can 5 to the take-up roll 4, a predetermined tension is applied to the base film 2 so that smooth travel can be obtained. Has been done.

In the vacuum chamber 1, a material supply device 9 is arranged below the cooling can 5.

As shown in FIGS. 2 and 3, the material supply device 9 accommodates a material container 12 in which a vaporization material 16 is filled inside a main body 17, and further an external power motor 15 and a material filling. It is composed of the tank 14.

FIGS. 4 and 5 are a plan view and a sectional view showing the structure of the material container 12, and as shown in these drawings, the material container 12 has a concave inner side, and the concave portion has a concave shape. The evaporation material 16 is filled.

The material container 12 is rotated by the external power motor 15 via a rotary gear.

Further, the same evaporation material as the evaporation material 16 is filled in the material filling tank 14,
While the material container 12 is rotating, when the evaporation material 16 filled in the material container 12 is insufficient, the evaporation material 16 is always supplemented. This makes it possible to evaporate by the electron beam emitted from the electron gun 10 which will be described later, to constantly replenish the deficient evaporation material, and to perform continuous evaporation.

The size of the particles used for the evaporation material 16 is preferably 1 mm or more and 1/3 or less of the depth of the material container 12. If the size of the particles is smaller than 1 mm, the particles will be easily scattered when the inside of the vacuum chamber 1 is evacuated, and conversely, the material container 1
If it is larger than 1/3 of the depth of 2, it will be difficult to fill the material container 12 and the rotation of the material container 12 may become defective.

On the other hand, an electron gun 10 for heating and evaporating the evaporation material 16 in the material supply device 9 is attached to the outer wall portion of the vacuum chamber 1 on the lower right side in the drawing. The electron gun 10 is arranged at a position such that the electron beam emitted from the electron gun 10 irradiates the evaporation material 16 in the material supply device 9. Then, the electron beam emitted from the electron gun 10 is linearly sweep-irradiated on the radial portion of the upper surface of the evaporation material 16 to heat and evaporate the evaporation material 16. Further, the evaporation material 16 that has been heated and evaporated is vapor-deposited on the base film 2 that runs at a constant speed on the peripheral surface of the cooling can 5 to form a thin film layer.

A shutter 8 is provided between the cooling can 5 and the material supply device 9 and near the cooling can 5. This shutter 8
Is formed in such a manner as to cover a predetermined region of the base film 2 traveling at a constant speed on the peripheral surface of the cooling can 5, whereby the vaporized evaporation material 16 is vaporized at a predetermined angle with respect to the surface of the base film 2. It is designed to be vapor-deposited obliquely within the range.

Further, in the vacuum chamber 1, a partition plate 1 is provided so as to divide the cooling can 5 into a lower side and an upper side.
1 is provided. Therefore, the base film 2 fed from the feed roll 3 by the partition plate 11
The vapor deposition is performed from the time when the vapor passes through the partition plate 11, and the vaporized material 16 that has been vaporized is not diffused to the upper side of the partition plate 11.

Therefore, a sample tape was prepared by vapor-depositing a SiO ₂ film on a base film using a vacuum vapor deposition apparatus having such a structure. Also, for comparison,
Instead of using the above-mentioned material supply device, a comparative tape was prepared using a conventional vacuum vapor deposition device that deposits quartz particles in a vapor deposition crucible and performs vapor deposition. The time dependence of the film thickness was investigated.

The vapor deposition conditions are as shown below.

<Deposition conditions> Electron gun power: 1 kW Vacuum degree: 3 × 10 ⁻³ Pa Incident angle: −7 to + 7 ° Deposition material: Quartz (SiO ₂ ) Deposition material shape: Particles (particle size 3 to 5 mm) As a result, as shown in FIG. 6, with the sample tape manufactured using the vacuum vapor deposition apparatus of this example, a SiO ₂ film having a stable film thickness could be continuously vapor deposited. On the other hand, in the comparative tape, the film thickness decreased as the quartz particles initially filled in the vapor deposition crucible disappeared, and it became impossible to continuously form the film after the time exceeded about 10 minutes.

[0052]

As is clear from the above description, in the present invention, the evaporation material is continuously supplied while the container filled with the evaporation material is rotated. Even when a so-called sublimable substance that does not melt but vaporizes, a film can be formed by continuous vacuum deposition.

Therefore, according to the present invention, the film formation of the sublimable protective film material or the like is performed very efficiently as compared with the conventional film forming technique such as the sputtering method or the CVD method. Therefore, the productivity is remarkably improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example of a vacuum vapor deposition apparatus used in a method for manufacturing a magnetic recording medium according to the present invention.

FIG. 2 is an enlarged cross-sectional view of an essential part showing a configuration example of a material supply device in the vacuum vapor deposition device.

FIG. 3 is an enlarged plan view of an essential part showing a configuration example of a material supply device in the vacuum vapor deposition device.

FIG. 4 is an enlarged plan view of an essential part showing a positional configuration example of a material container housed in the material supply device.

FIG. 5 is an enlarged sectional view of an essential part showing an example of the positional configuration of a material container housed in the material supply device.

FIG. 6 is a characteristic diagram showing the relationship between the elapsed time from the start of vapor deposition and the normalized film thickness.

[Explanation of symbols]

 1 Vacuum Chamber 2 Base Film 5 Cooling Can 8 Shutter 9 Material Supply Device 10 Electron Gun 12 Material Container 13 Rotating Gear 14 Material Filling Tank 15 External Power Motor 16 Evaporative Material 17 Main Body

Claims (2)

[Claims] 1. When a thin film made of an evaporation material is formed on a substrate by vacuum evaporation, the evaporation material is filled in a container having a concave inside, and evaporation is performed while rotating the container. And a method for manufacturing a magnetic recording medium. 2. The evaporation material is a particulate sublimable substance, and the size of the particles is 1 mm or more and 1/3 or less of the depth of the container. Manufacturing method of magnetic recording medium.