JPH10124870A - Production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to further improve vapor deposition efficiency and to lessen the yielding to heat and the degradation in a preservable property which are the defects of high-frequency heating in a process for producing a magnetic recording medium. SOLUTION: An evaporation source 11 is heated by a high-frequency induction heating coil 12 of a frequency of >=1kHz and an electron beam 31 emitted from an electron gun 30. Of the electron beam 31, the electron beam reflected by the melt surface of a magnetic material 10 is cast to a base film 3. This film 3 is brought into tight contact with a cooling can 4 by the Coulomb force of the electron beam 31 and the heat by the vapor deposition is made to adequately escape to the cooling can 4, by which the yielding to heat of the film 3 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetic recording medium, and more particularly, to a method of heating and melting a magnetic material, evaporating the magnetic material, and depositing the vapor flow on a flexible substrate such as a base film. The present invention relates to a method for manufacturing a magnetic recording medium in which a magnetic recording layer is formed by a so-called vapor deposition process for growing.

[0002]

2. Description of the Related Art Conventionally, as a magnetic recording medium, γ-Fe
₂ O ₃ , Co-doped Fe ₃ O ₄ , γ-Fe ₂ O ₃
Magnetic material as a berthollide compound of Fe ₃ O _4, berthollide compound doped with Co, from CrO _3, Ba oxide magnetic material such as ferrite, or Fe, Co, an alloy magnetic material mainly composed of Ni or the like Are dispersed and mixed together with additives into a polymer binder such as a vinyl chloride-vinyl acetate copolymer, a styrene-butadiene copolymer, an epoxy resin, or a polyurethane resin, and the dispersion mixture is mixed with polyethylene terephthalate (PET) or the like. 2. Description of the Related Art A so-called coating type magnetic tape which is manufactured by coating a base film (substrate) made of a polyolefin such as polyester or polypropylene and then curing or drying the base film is widely known.

On the other hand, in recent years, the demand for higher recording density has become stronger, and the density of the magnetic material in the magnetic layer of the magnetic recording medium has been increased, the coercive force has been improved, the magnetic layer has been reduced in thickness, or the frequency characteristics have been shortened. Consideration has been given to shifting to the side.

However, in a coating type tape, it is difficult to satisfy the above-described various conditions required for high-density recording because a binder remains in the magnetic layer.

Therefore, attention has been paid to a method of manufacturing a magnetic recording medium by a vapor deposition method such as vacuum deposition, sputtering, or ion plating, or a plating method such as electroplating or electroless plating, and various proposals have been made. According to these methods, the magnetic layer can be formed by depositing and growing a magnetic material directly on a substrate without using a binder, so that the packing density of the magnetic material in the magnetic layer is increased, and Can also be made thinner.

Further, these vapor deposition methods and the like make it easy to adjust and control the thickness of the film formed on the base film, adjust the coating solution of the magnetic layer in the manufacturing process of the coating type tape, and perform drying after coating. This has practically useful advantages such as eliminating the need for processing steps associated with the formation of a magnetic layer.

[0007] In particular, the vapor deposition method has the advantages that the waste liquid treatment required in the plating method is not required and that the growth rate of the deposited magnetic film is high.
A magnetic tape using a magnetic layer formed on a base film by such a vapor deposition method as a recording layer has a much higher reproduction output and a shorter frequency characteristic of a recording signal than a conventional coating type magnetic tape. It is useful as a high-density magnetic recording medium, for example, it is improved on the wavelength side.

It is known that the production of a magnetic recording medium by a vapor deposition method is performed in detail by, for example, a vacuum vapor deposition apparatus 1 shown in FIG. As shown in FIG.
A long base film 3 made of a non-magnetic material such as a polyester film, a polyamide film, or a polyimide film is formed inside a vacuum chamber 2 in a reduced pressure state. The cooling film 4 is wound in the direction Y. The cooling film 4 is rotated in the direction of arrow Y, and the base film 3 which is transferred from the side of the delivery shaft 5 to the side of the winding shaft 6 is provided on the outer peripheral surface of the cylinder. Conveyed.

The inside of the vacuum chamber 2 is controlled by a partition plate 7 to take up and wind up the base film 3 in a winding chamber 8.
And a deposition chamber 9 for depositing a magnetic material on the base film 3. In the vapor deposition chamber 9, Co, CoNi alloy, CoCr alloy, CoC
An evaporation container 11 containing a magnetic material 10 as an evaporation source such as an rNi alloy is provided, and the magnetic material 10 is heated and evaporated by heating means 12 such as electron gun heating, resistance heating, and high frequency induction heating. Particles of the magnetic material 10 (referred to as magnetic particles or evaporating particles), which evaporate and rise, are continuously deposited on the surface of the base film 3 conveyed in the direction of arrow Y with the rotation of the cooling can 4. They collide and deposit there by cooling, thus forming a magnetic layer.

Here, in order to efficiently deposit the evaporated magnetic material particles on the substrate to increase the vapor deposition efficiency, it is sufficient to prevent the evaporated particles from diffusing widely. According to the technique disclosed in Japanese Patent Application Laid-Open No. 2-56730, the portion between the evaporation source and the cooling can, around which the evaporated particles pass, is surrounded by a peripheral wall to regulate the flow path. In order to do so, for example, a steam diffusion control wall (steam diffusion control means) 15 having a cylindrical shape may be provided. The vapor diffusion control wall 15 has a temperature of the inner wall surface in order to re-evaporate or coagulate and collect the evaporated particles of the magnetic material 10 attached to the inner wall surface or to combine re-evaporation and coagulation and recovery. Is provided with means for heating or cooling.

When such a vapor diffusion control wall 15 is provided, it is difficult to use an electron gun heating means generally used as a heating means. That is, in this case, it is necessary to secure a passage of the electron beam from the electron gun to the magnetic material 10 placed in the evaporating vessel 11.
This is because, when the vapor diffusion control wall 15 is provided above the above, it is difficult to secure the passage trajectory of the electron beam. Therefore, high frequency induction heating means is usually used as the heating means.

The magnetic properties of the magnetic thin film formed on the base film by vapor deposition, particularly its coercive force, depend on the angle formed by the base film 3 when the vapor of the magnetic material 10 reaches the base film 3, ie, the evaporation container 11 The base film 3 of the magnetic material 10 scattered from inside toward the base film 3
Is determined by the angle of incidence on For this reason, usually, the cooling can 4 side of the evaporating vessel 11 (below the cooling can 4 in the figure).
Are provided with masks 13 and 14 serving as shielding members at a predetermined distance from the cooling can 4.
The maximum incident angle is regulated by the mask 13 located on the upstream side with respect to the transport direction, and the minimum incident angle is regulated by the mask 14 located on the downstream side, and the vapor of the magnetic material 10
Through the opening 18 formed by the base film 3 and 14, the liquid is supplied to the surface of the base film 3 from obliquely below in the drawing. The angle of incidence refers to an angle between the base film 3 and a straight line perpendicular to the surface of the base film 3.

It has been found that it is effective to spray oxygen during the vapor deposition in order to further improve the coercive force of the magnetic thin film. In the method of blowing oxygen, usually, a gas blowing unit 17 is provided near a mask 14 located on the downstream side in the transport direction of the base film 3 to blow oxygen gas to the evaporated particles of the magnetic material 10. It is done by. For example, according to the technology disclosed in Japanese Patent Publication No. 2-27732, the oxygen gas is blown from the vicinity of the minimum incident angle, and the inert gas is also blown from the vapor deposition start side (the maximum incident angle side). The filling rate and the magnetic filling rate are adjusted.

Although it is different from the purpose of improving the coercive force, oxygen gas is blown into the system during the vapor deposition also for the purpose of improving the corrosion resistance of the magnetic recording medium. For example, according to the technology disclosed in Japanese Patent Publication No. 3-19621, an oxidizing gas is sprayed into the system from a plurality of nozzles arranged in the width direction of a base film as a substrate to form an element constituting a magnetic layer. To form an oxide, and the oxide film of the oxide has a protective effect against corrosion.

On the other hand, in order to improve the production efficiency of a magnetic recording medium and the efficiency of vapor deposition of a magnetic material, a vacuum vapor deposition apparatus that heats an evaporation container by combining a method using electron gun heating and a method using induction heating has been proposed. (JP-A-5-219913). In this device, the evaporation energy of the magnetic material in the evaporation container is mainly given from the electron gun, and the energy due to the induction heating is transferred to the outside of the evaporation container out of the energy supplied as the evaporation energy from the electric gun as heat conduction or as radiation. It is used to supplement the energy that escapes. According to this apparatus, even if the output of the electron gun is reduced, the efficiency of vapor deposition of the magnetic material can be improved, so that a high-output electron gun is not required and the equipment cost can be reduced. Although the frequency of induction heating is relatively low, such as 30 to 50 Hz, a high frequency of, for example, 1 KHz is often used.

[0016]

However, in the heating method using an electron beam, the production efficiency of a magnetic recording medium or the vapor deposition efficiency of a magnetic material is low and the production cost is considerably required as described in JP-A-5-219913. Disadvantage. Although high-frequency induction heating can improve the vapor deposition efficiency as compared with the method using an electron beam, it has a problem in the process that heat loss easily occurs and a problem in quality that storage stability is inferior. Here, losing heat means
Among the wrinkles of the substrate (base film) generated during vapor deposition, those generated by thermal factors such as latent heat of evaporating particles and radiant heat from the evaporation container. Normally, the cooling can is cooled to about -30 ° C, and the substrate that comes into uniform contact with the surface can absorb heat (latent heat of evaporating particles and radiant heat from the evaporating vessel and scene) when the magnetic material adheres. By letting it escape to the cooling can side, its own temperature rise is suppressed. Here, if there is a portion where the base material is partially lifted from the cooling can, heat escape from the base material in that portion becomes worse, and the temperature of the base material increases. Thereafter, degassing from the substrate occurs as the temperature rises (both front and back of the substrate)
In addition, the temperature of the base material rises because the heat hardly escapes. On the other hand, since a tension is applied to the substrate in the transport direction, a portion where the substrate is softened due to a rise in the temperature of the substrate is elongated, and wrinkles are generated. The generation of the wrinkles is a heat loss.

In addition, the storability refers to the degree of deterioration of characteristics with respect to the environment of the medium, and is evaluated, for example, by corrosion due to sulfurous acid gas and change in surface reflectance under a high-humidity and high-temperature environment. The cause of the poor preservability of the magnetic recording medium deposited by high-frequency induction heating is considered to be the presence or absence of ionization of the evaporated particles or the introduced oxidizing gas molecules, or the effect of electron beam irradiation of the magnetic layer surface by reflected electrons.

Further, in the vacuum vapor deposition apparatus disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 5-271913, although the equipment cost can be reduced, the vapor deposition efficiency cannot be improved so much.

[0019]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above problems, and it is possible to further improve the vapor deposition efficiency, to prevent the heat loss which is a drawback of the high frequency induction heating, and at the same time to improve the storage stability. An object of the present invention is to provide a method of manufacturing a magnetic recording medium which can improve a magnetic recording medium, which transports a long flexible substrate in a vacuum atmosphere, and which is disposed below a path along which the substrate is transported. A vapor source that heats an evaporation source made of a material, evaporates the magnetic material, and regulates and controls a diffusion direction of a vapor flow generated by evaporation of the magnetic material, provided between the evaporation source and the flexible substrate. A flow diffusion control means, and an incident angle regulating means for regulating an incident angle of the vapor flow to the flexible substrate. The oxidizing gas is controlled while controlling the directivity of the vapor flow. To the steam flow In the method of manufacturing a magnetic recording medium in which the vapor flow is vapor-deposited on the surface of the flexible substrate while forming a magnetic thin film, the evaporation source is heated and evaporated by high-frequency induction heating and an electron beam. The method is achieved by a method for manufacturing a magnetic recording medium, which comprises irradiating a vapor stream generated by evaporation of a magnetic material and the oxidizing gas with the electron beam to ionize the oxidizing gas.

The input power for generating the high frequency induction heating and the electron beam is Pr and Pe, respectively.
It is desirable that the relationship be Pe / (Pr + Pe) <0.5, more preferably less than 0.3, and most preferably less than 0.1.

This is because it is difficult to control the electron beam when its input power is large.

The frequency of the high-frequency induction heating is as follows:
1 KHz to 500 KHz, more preferably 10 KHz to 200 KHz
KHz, most preferably 20 KHz to 50 KHz.

If it is less than 1 KHz, it is not suitable for heating and evaporating a material generally having a high melting point, such as a magnetic material.
On the other hand, even if the frequency exceeds 500 KHz, there is no remarkable effect.

The term “evaporation source” as used herein means a material formed of a magnetic material, but in the present specification, for convenience of explanation, the term “evaporation source” includes an evaporation container containing a magnetic material as an evaporation source. There is.

[0025]

In the method for manufacturing a magnetic recording medium according to the present invention, the evaporation container is heated by high-frequency induction heating of 1 KHz or more and an electron beam, so that the magnetic material in the evaporation container is mainly heated by high-frequency induction heating. It will be heated. As described above, since the magnetic material is mainly heated by the high-frequency induction heating, the vapor deposition efficiency of the magnetic material can be improved as compared with the heating by the electron beam.

On the other hand, the electron beam is applied to the magnetic material in the evaporation container, and this electron beam promotes ionization of an oxidizing gas or the like for oxidizing the evaporated particles and the evaporated particles generated from the gas ejection means. This means that about 10% of the electrons are reflected on the surface of the substrate as reflected electrons. Some of the reflected electrons are injected into the substrate and remain as space charges. This causes a Coulomb force between the space charge and the counter-induced charge induced on the cooling means for cooling the substrate, whereby the substrate adheres to the cooling means and the evaporated magnetic material Since the heat of the base material is satisfactorily released to the cooling means, heat loss of the base material does not occur. Further, the evaporating particles and the oxidizing gas for oxidizing the evaporating particles are also positively and negatively ionized by the electron beam, respectively, so that the oxidation of the evaporating particles by the oxidizing gas is promoted.

Further, as a result of an experiment conducted by the present applicant, the input power Pr to the high-frequency induction heating means and the input power Pe to the electron beam means are set so as to satisfy Pe / (Pr + Pe) <0.5. As a result, it was confirmed that stable generation of an electron beam was achieved, and that the evaporation efficiency was further improved and heat loss was less likely to occur.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments for carrying out a method for manufacturing a magnetic recording medium according to the present invention will be described with reference to the drawings. FIG. 1 shows a schematic configuration of an embodiment of a vacuum evaporation apparatus which is a magnetic recording medium manufacturing apparatus for carrying out a magnetic recording medium manufacturing method of the present invention.

The illustrated vacuum vapor deposition apparatus 1 has a cylindrical cooling can 4 inside a vacuum chamber 2, and a cylindrical film (outer peripheral surface) of the cooling can 4 has a base film as a base material of a magnetic recording medium. 3 is wound. The base film 3 is made of a polyester such as polyethylene terephthalate (PET) or polyethylene naphthalate, a polyolefin such as polypropylene, a cellulose dielectric such as cellulose triacetate or cellulose diacetate, a vinyl resin such as polyvinyl chloride,
It is formed by processing a plastic such as polycarbonate, polyamide, or polyphenylene sulfide into a long film, and the thickness thereof is, for example, 3 to 100 μm. In this embodiment, the one having a thickness of 6 μm is used.

An undercoat is applied to the surface of the base film 3 if necessary. The undercoat is made of a binder (cellulose such as methylcellulose, P
Saturated polyesters such as ET, phenoxy resins, polyamides, polyacrylates, etc.) and fillers (silica, titania, alumina, calcium carbonate, etc.) are dissolved and applied, and the surface projections have a height of 5 to 30 nm.
In those with a protrusion density 5000000-100000000 pieces / mm ^2. In this embodiment, the particle size is 18 μm and the density is 5500.
10,000 / mm ² . The height and density can be appropriately selected depending on the required adhesion performance and the like.

Further, the base film 3 may be subjected to a pretreatment such as a glow discharge treatment, an ion irradiation treatment, a heat treatment, and a chemical treatment.

The base film 3 is wrapped around the take-up shaft 6 from the delivery shaft 5 via the cylindrical surface of the cooling can 4, and is rotated on the cylindrical surface of the cooling can 4 by rotating the cooling can 4 in the direction of arrow Y. For example, it is conveyed at a speed of 10 to 100 m / min, and is taken up on a take-up shaft 6. The cooling can 4 has a diameter
It is a cylindrical drum of 600 mm and width of 220 mm. The surface is hard chrome plated and mirror-polished to 0.3 S or less. Cooling water and other refrigerant (ethylene glycol) are circulated inside. For example, it is maintained at −35 to + 25 ° C. (−28 ° C. in the present embodiment).

On the surface of the cooling can 4, masks 13 and 14 whose main body is formed of SUS304 or the like are provided, circulating cooling water or a coolant inside the cooling can 4 at a predetermined distance. This distance is between 2 and 15 mm, more preferably between 2 and 10 mm, most preferably between 3 and 5 mm. If it is smaller than 2 mm, a space for installing a first gas blowing section described later cannot be secured, and if it is larger than 15 mm, the vapor flow wraps between the mask and the base film and adheres to the cooling can 4, which causes contamination. Because it becomes. This is because the heat transfer coefficient between the can and the base film changes in the portion where the dirt is generated, or the adhesion of the can to the base film becomes insufficient and the can becomes easily damaged by heat. The mask 13 located on the upstream side with respect to the transport direction of the base film 3 makes the maximum incident angle (θmax) the mask 14 located on the downstream side.
Defines the minimum incident angle (θmin). The angle of incidence is based on the center of the circle of the melted surface in the refractory crucible 11a, which will be described later. The maximum incident angle (θmax) regulated by the mask 13 is limited to 90 °, more preferably 87 °, most preferably 85 °, and the minimum incident angle regulated by the mask 14. Angle (θmin) is 20 °,
More preferably, the lower limit is set to 25 °, most preferably 30 °. This is because a desired coercive force cannot be obtained outside the above range.
The opening width of the mask opening 18 formed by the masks 13 and 14 in the width direction (perpendicular to the transport direction of the base film 3) can be set arbitrarily.

On the front surfaces of the masks 13 and 14, the masks 13 and 14 are curved along the masks 13 and 14, respectively.
And has a function of preventing the evaporated metal particles of the magnetic material 10 from adhering to the surface of the base material 3, circulating cooling water inside, and a movable type having a main body formed of SUS304 or the like. (Not shown).

The vacuum chamber 2 includes a winding chamber 8 for feeding and winding the base film 3 by a partition plate 7,
The base film 3 is partitioned into a deposition chamber 9 for depositing a magnetic material. Each of the winding chamber 8 and the vapor deposition chamber 9 is provided with an exhaust system (not shown) for reducing pressure, and the pressure in each chamber can be adjusted individually. In particular, since an oxidizing gas, which will be described later, is introduced into the vapor deposition chamber 9 from the outside of the vacuum chamber 2, the pressure in the chamber and the partial pressure of various residual gases are constantly adjusted by adjusting means (not shown).

Further, the winding film 8 contains the base film 3.
For the pre- and post-treatments described above, for example, glow discharge treatment device, ion irradiation treatment device, heat treatment device, C
A VD processing device or the like may be provided. In addition, cooling can 4
Is not limited to a cylindrical shape, and may be an endless belt-shaped metal plate capable of forming a predetermined slope with respect to the evaporating container 11.

An evaporating vessel 11 containing a magnetic material 10 is disposed below the cooling can 4 in the vapor deposition chamber 9.
Around the periphery of 11, a high-frequency induction heating coil 12 having a tubular structure through which cooling water circulates for heating the magnetic material 10 is provided. Further, a high-frequency power supply 20 for supplying high-frequency power to the high-frequency induction heating coil 12 and a high-frequency power supply feeder 21 for circulating cooling water in a tube of the high-frequency induction heating coil 12 are provided.

The magnetic material 10 is made of, for example, Fe, Co, Ni,
CoNi, FeCo, FeCu, FeCr, CoCr,
CoCu, CoAu, CoPt, CoW, NiCr, C
oV, MnBi, MnAl, CoFeCr, CoNiC
r, CoRh, CoNiPt, CoNiFe, CoNi
It is appropriately selected from ferromagnetic metals and ferromagnetic alloys such as FeB, FeCoNiCr, and CiNiZn.

The magnetic material 10 which is a component of the evaporation vessel 11
The refractory crucible 11a for containing MgO, ZrO
₂ , Al ₂ O ₃ , CaO, Y ₂ O ₃ , ThO ₂ , BN,
BeOCaO stabilized ZrO ₂ , Y ₂ O ₃ stabilized ZrO ₂
And other materials having heat resistance, such as ceramics, carbon or carbon compounds, and other materials having heat resistance. In addition, this refractory crucible 11
The shape of a is a container type having a bottom, and the horizontal cross-sectional shape may be a perfect circle, an ellipse, an oval, a square, a rectangle, or any other shape, and the vertical cross-section is also a square.
It may be rectangular, trapezoidal, or any other shape.
Preferably, the high-frequency induction heating coil 12 has a shape corresponding to the side surface of the refractory crucible 11a.

Further, the vapor deposition chamber 9 is located between the cooling can 4 and the evaporation vessel 11 provided with the magnetic material 10,
A steam flow diffusion control means 15 is provided as means for preventing the diffusion of steam so as to surround a path through which a steam flow generated by evaporation of the gas passes. In the vicinity of 14, a gas blowing unit 17 for injecting a mixed gas of an acidifying gas or an oxidizing gas and an inert gas toward the base film 3 is provided.

The gas blowing section 17 is located downstream with respect to the direction of transport of the base film 3 and is built in the surface of the mask 14 on the side of the cooling can 4 near the mask 14 which regulates the minimum incident angle (θmin). ing. In addition, O ₂
Gas was used. The blowing direction of the gas injection slit 17a is substantially parallel to the tangent line on the cooling can 4 at the reference point on the cooling can 4 which defines the minimum incident angle (θmin). Relative scattering direction of the evaporation particles that has passed through the opening of the steam flow diffusion control means 15 which will be described later by spraying O ₂ gas from the gas blowing part 17, in a substantially diagonal direction of the O ₂ gas is blown evaporated metal particles one Oxidize parts.

The inner peripheral wall surface of the vapor flow diffusion control means 15 is, for example, MgO, ZrO ₂ , Al ₂ O ₃ , CaO, Y ₂ O ₃ ,
ThO ₂ , BN, BeOCaO stabilized ZrO ₂ , Y ₂ O
₍₃₎ A steam flow path formed of ceramics such as stabilized ZrO ₂ , carbon or a carbon compound, or other heat-resistant material, and surrounded by a regulating surface extending substantially vertically in a state substantially continuous with the refractory crucible 11a. Are arranged so that
The lower surface and the upper surface are cylindrical so as to allow the passage of evaporated particles of the magnetic material 10 and improve the directivity thereof, and have a cylindrical shape having only a peripheral wall, and have a horizontal cross-sectional shape of a circle, an ellipse, an oval, and a square. , A rectangle, or any other shape. The vertical cross-section may also be square, rectangular, trapezoidal, or any other shape.

Further, the vapor flow diffusion control means 15 is, for example,
From the center of the opening toward the outside, concentric circles of the inner wall 15a,
It has a laminated structure composed of a plurality of members such as two layers of the outer peripheral portion 15c.

Further, an electron gun 30 having a maximum output of 30 kW for irradiating the magnetic material 10 of the refractory crucible 11a with an electron beam.
Is provided. The electron beam is emitted from the electron gun 30 in the horizontal direction, but a deflecting magnetic field acts on the vicinity of the evaporating vessel 11, so that the electron beam is directed to the magnetic material 10 in the crucible 11a whose orbit is bent downward. Irradiated directly.

[0045]

EXAMPLE A refractory crucible 11a of this example has a cup shape (inner diameter φ80 mm, outer diameter φ96 mm, height 100 mm, inner depth 90 mm).
mm) and the material is Y ₂ O ₃ stabilized ZrO ₂ (Zr
_{O 2; 88.0% ~95.0%,} Y 2 O 3; with 5.0% to 12.0%). Co ₉₅ Ni ₅ was used as a ferromagnetic material 10 for evaporation inside the refractory crucible 11a.

The high-frequency induction heating coil 12 is made of a Cu pipe having a diameter of φ12 mm through which cooling water circulates. The high-frequency induction heating coil 12 has eight turns, an inner diameter of φ120 mm, and a height h105 mm. Two high-frequency power supplies 20 with an oscillation frequency of 25 kHz and an output of 40 kW are installed outside the vacuum chamber 2, and are set to 1 kHz
The high frequency induction heating coil 12 disposed inside the vacuum chamber 2 was connected to the high frequency feeder 21 and the feed through for vacuum (not shown). High frequency feeder 21
Are made of a Cu plate, and the extended Cu pipe portions of the high-frequency induction heating coil 12 are each surrounded by an insulating tube made of Al ₂ O ₃ and are electrically insulated from each other.

The inner wall portion 15a of the vapor diffusion control means 15 has a cylindrical shape (inner diameter φ80 mm, outer diameter φ96 mm, height h50 mm) and is made of CaO-stabilized ZrO ₂ (ZrO ₂ ; 90.0%).
% To 98.0%, CaO; 2.0% to 7.0%, MgO, Al ₂
Each component of O ₃ , SiO ₂ , FeO ₃ , and TiO ₂ is 0.0%
~ 2.0%).

The outer peripheral portion 15c was formed in a cylindrical shape (inner diameter φ96 mm, outer diameter φ140 mm, height h50 mm), circulated cooling water inside, and formed a cooling structure in which the main body was formed of oxygen-free copper.

Next, the operation of the magnetic recording medium manufacturing apparatus of this embodiment will be described.

First, a gas such as air in the vapor deposition chamber 9 and the winding chamber 8 is exhausted to the outside by a decompression means (not shown) such as a vacuum pump. For example, 5.0 × 10 ^{-5 to} 4.0 × 10 ^-4 To
The pressure is reduced to rr. In this example, 5.0
× 10 ^-5 Torr. After the insides of the vapor deposition chamber 9 and the winding chamber 8 are depressurized as described above, power is supplied to the high-frequency induction heating coil 12 using the high-frequency power supply 13, whereby the high-frequency induction heating coil 12 generates heat and evaporates. 11 magnetic materials 10
Was heated and evaporated.

After the magnetic material 10 is completely dissolved and the evaporation rate becomes constant, the base film 3 is moved by the delivery shaft 5.
At a transport speed of 60 m / min and a tension of 2.0 kgf / 100 mm. In a pretreatment chamber (not shown), the side of the base film 3 on which the magnetic thin film is formed is subjected to glow discharge treatment using O ₂ gas. After the application, it was transported on the cooling can 4.
Then, the shutter device is driven to an "open" state. Then, the electron gun 30 is operated to irradiate the evaporation surface of the magnetic material 10 with an electron beam. High frequency induction heating power supply at this time
The output of 20 was 8 KW, and the output of the electron gun 30 was 4 KW.
At the same time, O ₂ gas is sprayed from the gas spray unit 17 at a spray rate of 300 cc / min.
The first layer of C is sprayed on the base film 3 while injecting gas.
After forming an oNi—O magnetic thin film (thickness: 700 Å), it is continuously wound on a winding shaft 6 and has a length of 3,000.
After the metal magnetic thin film of m is formed, the shutter device is set to the "open" state, and at the same time, the O ₂ gas is blown from the gas blowing unit 17, the power is supplied from the high frequency power supply 20, and the electron gun 30 is stopped. The film formation of the layer was completed.

The web once wound on the winding shaft 6 is as follows:
The paper is sent out from the winding shaft 6 by the reverse rotation operation, and is rewound on the feeding shaft 5. Thereafter, a second layer of Co—O magnetic thin film (thickness: 700 Å) is formed by the same vapor deposition method described above, and a two-layer magnetic thin film (total thickness of 14 Å) is formed.
00 angstroms).

After depositing a magnetic thin film on the base film 3 and correcting the curl of the magnetic layer by a heat treatment, the surface of the magnetic thin film is formed as a phosphoric acid monoester compound as C ₁₂ H _25.
A solution of OPO ₃ H ₂ in methyl ethyl ketone was applied so that the coating amount on the magnetic layer was 20 μmol / m ² and dried. Subsequently, a resin composition comprising carbon black and a resin binder is applied to the surface opposite to the surface on which the magnetic layer has been formed, and dried to form a backcoat layer.As a fatty acid ester compound on this backcoat layer, C ₈ F ₁₇ COOC ₁₈
Applying a solution of H ₃₇ in ethanol so that the 20 [mu] mol / m ^2, was wound up dry. The above process is performed by varying the outputs of the high-frequency induction heating coil 12 and the electron gun 30 to obtain a raw material on which a magnetic thin film is formed, and the raw material is cut into an 8 mm width to obtain a magnetic recording medium for evaluation. Created.

Then, the following preservability and heat loss were evaluated.

[Evaluation Method of Storage Property] (1) The magnetic recording medium was stored for 72 hours in an environment of 27 ° C., 80% RH, and 1 ppm of sulfur dioxide gas. Is not observed, the metal gloss on the entire surface of the tape is retained but corrosion is observed, and the magnetic layer is partially or wholly dissolved by corrosion.

(2) The tape was stored in an environment of 60 ° C. and 90% RH in a reel wound state for 72 hours, and the visible light reflectance of the portion in contact with the back surface was measured and compared with the reflectance before the test.

[Method of Evaluating Heat Loss] The occurrence of heat loss was visually observed on the front surface side by irradiating visible light from the back side of the vapor-deposited raw material having a width of 100 mm and a length of 3000 m. The inspection position was investigated for 1000 m between 1000 m and 2000 m based on the evaporation start position.

The evaluation criteria are as follows: a double circle indicates no heat loss, a circle indicates no heat loss within ± 30 mm from the center in the base width direction, and a continuous heat loss (longitudinal direction). To 20 mm or more) is not recognized, but the heat loss that occurred alone is less than 10 places.
Continuous heat loss is not recognized, but heat loss that occurred alone at 10 or more places is △ ×, continuous heat loss (having a length of 20 mm or more in the longitudinal direction) is x, always heat XX indicates wrinkles due to losing.
Table 1 below shows the results of evaluating the storage stability and heat loss.

The total evaporation amount W _mev (g) is calculated from the difference between the total charge weight W _ms (g) of the ferromagnetic material 10 before melting and the residual material W _me (g) after the end of the vapor deposition. The total vapor weight W _bev (g) is calculated from the difference between the total weight before the base and the total weight W _be (g) after the vapor deposition. The ratio of the total evaporation weight W _bev (g) to the total evaporation amount W _mev (g) is defined as the evaporation efficiency ξ (%).

Ξ (%) = W _bev (g) / W _mev (g) × 100 (%)

[0061]

[Table 1]

Here, assuming that the output of the electron gun is Pe and the output of the high-frequency induction heating is Pr, 0.1 <Pe / (Pr + P
e) In the range of <0.5, heat loss and storage stability are effective, and the vapor deposition efficiency does not decrease, so that the range is practically applicable. A desirable range is 0.2 <Pe /
(Pr + Pe) <0.45, and the most desirable range is 0.
27 <Pe / (Pr + Pe) <0.36.

As the rate of electron beam heating increases, the evaporation efficiency decreases because the region through which the electron beam passes (the inner wall surface of the vapor flow diffusion control means) is heated.
It is considered that re-deposition of the adhered material becomes remarkable, and as a result, the ratio of vapor scattered to a region other than the adhered region of the substrate increases.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a manufacturing apparatus for carrying out a method for manufacturing a magnetic recording medium according to the present invention.

FIG. 2 is a diagram showing a conventional magnetic recording medium manufacturing apparatus.

[Description of Signs] 1 Vacuum evaporation device 2 Vacuum tank 3 Base film 4 Cooling can 5 Delivery shaft 6 Winding shaft 7 Partition plate 8 Winding room 9 Deposition room 10 Magnetic material 11 Evaporation container 11a Refractory crucible 12 High frequency induction heating Coils 13, 14 Mask 15 Vapor flow diffusion control means 17 Gas spray section 18 Mask opening 30 Electron gun

Claims (2)

[Claims] 1. A method for transporting a long flexible substrate in a vacuum atmosphere, and heating an evaporation source made of a magnetic material disposed below a path along which the substrate is transported, thereby forming the magnetic material. Through a vapor flow diffusion control means provided between the evaporation source and the flexible substrate, which regulates and controls the diffusion direction of the vapor flow generated by the evaporation of the magnetic material. The incident angle restricting means for restricting the incident angle to the flexible substrate is provided to control the directivity of the vapor flow, and further, while blowing the oxidizing gas onto the vapor flow, A method for manufacturing a magnetic recording medium, wherein a magnetic thin film is formed by vapor deposition on a surface of a flexible substrate, wherein the evaporation source is heated and evaporated by high-frequency induction heating and an electron beam, and vapor generated by evaporation of the magnetic material When the irradiation with the electron beam in an oxidizing gas, a method of manufacturing a magnetic recording medium, characterized in that ionizing. 2. The method according to claim 1, wherein the input power for generating said high-frequency induction heating and said electron beam is Pr and Pe, respectively, and the relation is Pe / (Pr + Pe) <0.5. A method for manufacturing a magnetic recording medium.