JP2000311339A - Apparatus for production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obviate the occurrence of cracks and fissures in an evaporation source assembly, such as a crucible, even in the stage of the initial period of heating of magnetic material with an apparatus for production of magnetic recording media. SOLUTION: A material 11b to be inductively heated is disposed between the refractory crucible 11a and high-frequency induction heating coil 12 constituting the evaporation source assembly 11. The relationship between the coefficient αc of thermal expansion of the refractory crucible 11a and the coefficient αi of thermal expansion of the material 11b to be inductively heated is specified to αc>αi. In heating by the high-frequency induction heating coil 12, the material 11b to be inductively heated is heated as well together with the magnetic material 10 in the crucible 11a, by which the crucible 11a is heated from both of the inner and outer sides and the occurrence of the cracks and fissures by the difference in the thermal expansion may be prevented. Further, the crucible 11a expands more largely than the material 11b to be inductively heated and, therefore, even if the inside and outside diameters are changed by the thermal expansion upon rising of the temperature of the crucible 11a to high temperature, the inside and outside diameters change to the direction where the spacing between the crucible 11a and the material 11b to be inductively heated is reduced and there is no more spacing. Since the circumference of the crucible 11a is protected by the material 11b to be inductively heated, its mechanical strength is improved and the occurrence of the fissure by the thermal expansion may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing a magnetic recording medium, and more particularly to a method for heating and melting a metal material, evaporating the metal material, and evaporating the vapor flow on a substrate such as a base film. The present invention relates to an apparatus for manufacturing a magnetic recording medium in which a magnetic recording layer is formed.

[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 Particles are dispersed and mixed together with additives in an organic binder such as a vinyl chloride-vinyl acetate copolymer, a styrene-butadiene copolymer, an epoxy resin, a polyurethane resin, and the dispersion mixture is mixed with a polyester such as polyethylene terephthalate (PET). 2. Description of the Related Art A so-called coating type magnetic tape is widely known, which is manufactured by coating a base film (substrate) made of polyolefin such as polypropylene or polypropylene and then drying the base film.

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 increased, the coercive force has increased, the frequency characteristics have shifted to shorter wavelengths, or Improvements such as thinning of the layers have been made. However, in the coating type tape, since the binder remains in the magnetic layer, it is difficult to satisfy the above-described conditions required for high-density recording.

Accordingly, 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.

In addition, these vapor deposition methods and the like make it easy to control the adjustment of the film thickness 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.

In particular, the vapor deposition method has the advantages that the waste liquid treatment required in the plating method is unnecessary and that the growth rate of the 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.

The production of the magnetic recording medium by the vapor deposition method can be performed in detail by, for example, a vacuum vapor deposition apparatus 1 shown in FIG. As shown in FIG. 3, the vacuum deposition apparatus 1 has a cylindrical shape and a non-cylindrical outer surface such as a polyester film, a polyamide film, or a polyimide film on the outer peripheral surface of a vacuum chamber 2 in a substantially vacuum state. A cooling can 4 for winding a long base film 3 made of a magnetic material in the longitudinal direction is provided. The cooling can 4 rotates in the arrow Y direction to send out the base film 3 and take up the winding shaft 6 from the shaft 5 side. To the side.

The inside of the vacuum chamber 2 is wound by a partition plate 7 into a winding chamber 8 for feeding and winding the base film 3.
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 source 11 provided with a magnetic material 10 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. The particles of the magnetic material 10, which evaporate and rise, are continuously deposited as a magnetic layer on the surface of the base film 3 conveyed in the direction of arrow Y with the rotation of the cooling can 4.

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 technology disclosed in Japanese Patent Application Laid-Open No. 2-56730, a cylindrical shape is provided between the evaporation source and the cooling can so that the peripheral wall surrounds a portion through which the evaporated particles pass. What is necessary is just to provide the vapor diffusion prevention means 15.

When such a cylindrical vapor diffusion preventing means 15 is provided, it is difficult to use an electron gun heating means generally used as a heating means. In other words, in this case, it is necessary to secure the trajectory of the electron beam from the electron gun to the magnetic material 10 in the evaporation source 11.
This is because, when the vapor diffusion preventing means 15 is provided above the electron beam 11, it is difficult to secure a passage trajectory of the electron beam. Therefore, high frequency induction heating means is usually used as the heating means.

[0011]

In the apparatus for manufacturing a magnetic recording medium as described above, a magnetic material is accommodated in a refractory crucible and the magnetic material in the crucible is heated using high-frequency induction heating means. . During this heating, the high-frequency induction current flows intensively on the outer peripheral portion of the magnetic material in the crucible, so that only the outer peripheral portion of the magnetic material is heated in the initial stage of heating. At this time, the refractory crucible containing the magnetic material is also heated, but only the inner wall of the crucible is heated, and heat is not sufficiently transmitted to the outer peripheral portion of the crucible at the initial stage of heating. A temperature difference occurs between the inner wall and the outer periphery of the crucible. Due to the temperature difference between the inner wall portion and the outer peripheral portion, a difference in thermal expansion occurs between the inner wall portion and the outer peripheral portion of the crucible, and as a result, cracks are generated around a portion of the crucible having mechanical distortion or a portion where the material is not uniform. In the worst case, the crucible may be broken.

In view of the above circumstances, it is an object of the present invention to provide an apparatus for manufacturing a magnetic recording medium in which a crack or a crack does not occur in an evaporation source such as a crucible even at an early stage of heating a magnetic material. Things.

[0013]

According to the present invention, there is provided an apparatus for manufacturing a magnetic recording medium for heating a magnetic material as described above by high-frequency induction heating.
An induced heating member surrounding the evaporation source is provided between the evaporation source and the high-frequency induction heating means, and a coefficient of thermal expansion αc of the evaporation source and a coefficient of thermal expansion αi of the induced heating member satisfy a relationship of αc> αi. It is characterized by having something like that.

In the heating state of the evaporation source, the thermal expansion coefficient αc (1 / K) of the evaporation source and the outer diameter Dc (m
m), inner wall surface temperature Tci (K), outer wall surface temperature Tco
(K), the coefficient of thermal expansion αi (1 /
K), the outer diameter Di (mm), the inner wall surface temperature Tii (K), and the outer wall surface temperature Tio (K) are: t ₀ = Di · αi · (Tii + Tio) / 2−Dc · α
When c · (Tci + Tco) / 2, the gap t _ci between the evaporation source and the induced heating member at room temperature preferably has a relation of 0.5 · t _ci ≦ t ₀ ≦ 2.0 · t _ci .

Here, "room temperature" means a temperature in a general manufacturing factory, and is generally 10 to 30 ° C.

Further, a gap between the evaporation source and the induction-heated material is filled with a powder-like filler made of at least one of a metal, oxide, carbide, nitride, and boride having a particle size of 0.3 mm or less. Is preferred.

It is preferable that a gap between the evaporation source and the induction-heated material is filled with a heat-resistant member having a melting point of 1600 K or more.

[0018]

In the apparatus for manufacturing a magnetic recording medium according to the present invention, an induction heating member surrounding the evaporation source is provided between the evaporation source and the high frequency induction heating means. The induced heating member will be heated together with the magnetic material in the source. For this reason, the evaporation source is heated simultaneously with its inner wall as well as its outer peripheral portion, so that even at the initial stage of heating, the temperature difference between the inner wall portion and the outer peripheral portion of the evaporation source is eliminated, and the difference between the inner wall portion and the outer peripheral portion is not expanded. . Therefore, generation and cracking of the evaporation source due to a difference in thermal expansion between the inner wall portion and the outer peripheral portion of the evaporation source can be prevented. In addition, since the thermal expansion coefficient αc of the evaporation source and the thermal expansion coefficient αi of the guided heating member are set to have a relationship of αc> αi, when the evaporation source is heated, the evaporation source becomes closer to the guided heating member. As a result, it expands significantly due to heat. Therefore, when the temperature of the evaporation source becomes high and the inner and outer diameters change due to thermal expansion, the inner and outer diameters change in a direction to reduce the gap between the evaporation source and the induced heating member. This allows the evaporation source to be close to the guided heating member and protect its surroundings, so that the mechanical strength of the evaporation source is improved, and cracks due to thermal expansion can be prevented.

In the heating state of the evaporation source, the thermal expansion coefficient αc (1 / K) of the evaporation source, the outer diameter Dc (mm), the inner wall surface temperature Tci (K), the outer wall surface temperature Tco (K), Coefficient of thermal expansion αi (1 / K) of heating member, outer diameter Di (m
m), inner wall surface temperature Tii (K), outer wall surface temperature Tio
The relation of (K) is t ₀ = Di · αi · (Tii + Tio) / 2−Dc · α
When c · (Tci + Tco) / 2, the gap t _ci between the evaporation source and the induction-heated material at room temperature has a relation of 0.5 · t _ci ≦ t ₀ ≦ 2.0 · t _ci , whereby the evaporation source The gap between the heating source and the guided heating member has an appropriate dimension, that is, a dimension where there is no gap between the evaporation source and the guided heating member even if the evaporation source and the guided heating member are heated and expanded due to thermal expansion. As a result, the evaporation source is prevented from being compressed in the inner diameter direction by the induced heating member due to the difference in the coefficient of thermal expansion, so that cracking does not occur.

Further, a gap between the evaporation source and the induction-heated material is filled with a powder-like filler made of at least one of a metal, an oxide, a carbide, a nitride, and a boride having a particle size of 0.3 mm or less. By this, it is possible to absorb to some extent the geometrical deviation due to thermal expansion and other distortions of the evaporation source and the guided heating member, and thus, when the evaporation source and the guided heating member thermally expand, Can be prevented from occurring, and the generation and cracking of the evaporation source can be prevented.

Also, by filling the gap between the evaporation source and the induction-heated material with, for example, a sheet-like heat-resistant member having a melting point of 1600 K or more, the heat generation of the evaporation source and the induction-heated member can be reduced. It is possible to prevent a gap from being formed between the evaporation source and the induced heating member, and to prevent generation and cracking of the evaporation source.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic recording medium manufacturing apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a vacuum evaporation apparatus 1 which is a magnetic recording medium manufacturing apparatus of the present invention.

The illustrated vacuum evaporation 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 3 as a substrate of a magnetic recording medium. 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.

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
It is applied by dissolving saturated polyester such as ET, phenoxy resin, polyamide, polyacrylate, etc.) and filler (silica, titania, alumina, calcium carbonate, etc.), has a thickness of 5 to 30 nm, and a density of 5 million. ~Ten
It has projections of 10 million / mm ² .

Further, the base film 3 is subjected to glow discharge treatment, electron beam irradiation treatment, ion irradiation treatment, heat treatment,
Pretreatment of chemical treatment may be performed.

The base film 3 is wrapped around the take-up shaft 6 from the delivery shaft 5 through the cylindrical surface of the cooling can 4, and rotates 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
This is a cylindrical drum of 800 mm and width of 400 mm. The surface is hard chrome plated and mirror-polished to 0.2 S or less. Cooling water and other refrigerant (ethylene glycol) are circulated inside. For example, it is maintained at -35 to + 25 ° C.

The surface of the cooling can 4 is separated from the cooling can 4 by a distance of 5 mm, and cooling water of 20 ° C. is circulated therein.
Masks 13 and 14 whose main body is formed of SUS304 are provided. The maximum incident angle (θmax) is defined by the mask 13 located on the upstream side in the transport direction of the base film 3 and the minimum incident angle (θmin) is defined by the mask 14 located on the downstream side in the transport direction of the base film 3. The angle of incidence is based on the center of the circle of the melted surface in the refractory crucible 11a to be described later, and the line segment from the center of this circle to the edge of the mask 13 and the mask 14 and the normal line at each mask edge position on the cooling can 4. The maximum incident angle (θmax) regulated by the mask 13 was set to 90 °, and the minimum incident angle (θmin) regulated by the mask 14 was set to 45 °. Mask 13 and
The opening width of the mask opening 18 formed by 14 in the width direction (perpendicular to the transport direction of the base film 3) is 280 mm.
Set to.

On the front surfaces of the masks 13 and 14, each of the masks 13 and 14 has a curved shape.
Has a function of preventing the evaporated metal particles of the magnetic material 10 from adhering to the surface of the base material 3,
A movable shutter device in which cooling water of 18 ° C. is circulated and whose main body is formed of SUS304 is provided (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. The take-up chamber 8 and the vapor deposition chamber 9 are each provided with an exhaust system (not shown) for evacuating the vacuum, and the degree of vacuum in each chamber can be individually adjusted. In particular, since the oxidizing gas described later is introduced into the vapor deposition chamber 9 from outside the vacuum chamber 2, the degree of vacuum in the chamber and the partial pressure of various residual gases such as H ₂ O and O ₂ are constantly adjusted.

The take-up chamber 8 contains the base film 3.
For example, a device for the pre- and post-treatment described above, such as a glow discharge treatment device, an electron beam irradiation treatment device, an ion irradiation treatment device, a heat treatment device, and a CVD treatment device may be provided. Further, the cooling can 4 is not limited to a cylindrical shape.
An endless belt-shaped metal plate that can form a predetermined slope with respect to the evaporation source assembly 11 may be used.

An evaporation source assembly 11 provided with a magnetic material 10 is disposed below the cooling can 4 in the evaporation chamber 9. As shown in FIG. 2, the evaporation source assembly 11 includes a refractory crucible 11a for accommodating the magnetic material 10 and a gap t ₀ outside the refractory crucible 11a so as to surround the refractory crucible 11a.
An induction heating member 11b arranged with a gap therebetween and a high-frequency induction heating coil 12 for heating the magnetic material 10 arranged around the induction heating member 11b are 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 transmitting high frequency power to the high frequency induction heating coil 12 are provided. The inside of the high-frequency induction heating coil 12 and the high-frequency power supply feeder 21 has a structure in which cooling water circulates.

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.

Magnetic material which is a component of the evaporation source assembly 11
The refractory crucible 11a for containing 10 is, for example, MgO, Zr
O ₂ , Al ₂ O ₃ , CaO, Y ₂ O ₃ , ThO ₂ , B
N, BeOCaO stabilized ZrO ₂ , Y ₂ O ₃ stabilized Zr
It is appropriately selected from ceramics such as O ₂ , carbon or a carbon compound, and other heat-resistant materials. The shape of the refractory crucible 11a is a container shape having a bottom, and the horizontal cross-sectional shape may be a true circle, an ellipse, an oval, a square, a rectangle, or any other shape, and the vertical cross-section may be a square. , Rectangular, trapezoidal, or any other shape. In the present embodiment, the refractory crucible 11a is, for example, cup-shaped (inner diameter φ80 mm, outer diameter φ96 mm, height 10 mm).
0 mm, internal depth 90 mm, coefficient of thermal expansion 1.0 × 10 ⁻⁶ ), and the material is CaO-stabilized ZrO ₂ (chemical component (wt%)
_{ZrO 2; 90.0% ~98.0%,} CaO; 2.0% ~7.0%)
Was used. Co ₁₀₀ was used as the ferromagnetic material 10 for evaporation inside the refractory crucible 11a.

Further, cup-like carbon (for example, an inner diameter of 98 mm, an outer diameter of 110 mm, a height of 115 mm, a depth of 110 mm) is used as the induction heating member 11b disposed on the outer periphery of the refractory crucible 11a.
mm. The material of the cup-shaped carbon serving as the induction heating member 11b is graphite carbon (molded product), and has a coefficient of thermal expansion of 5.0 × 10 ⁻⁶ / K.

Further, a filler 11c is filled in the refractory crucible 11a and the induction-heated member 11b. Filling material 11c
The material is powdery, with a particle size of 0.3 μm to 1.0 m
m CaO-stabilized ZrO ₂ (chemical component (wt%) ZrO
₂ ; 90.0% to 98.0%, CaO; 2.0% to 7.0%). This is filled while squeezing lightly from the bottom.

Here, in the heating state of the evaporation source assembly 11,
Thermal expansion coefficient αc (1 / K), outer diameter D of refractory crucible 11a
c (mm), inner wall surface temperature Tci (K), outer wall surface temperature Tc
o (K), the coefficient of thermal expansion αi (1 /
K), the outer diameter Di (mm), the inner wall surface temperature Tii (K), and the outer wall surface temperature Tio (K) are: t ₀ = Di · αi · (Tii + Tio) / 2−Dc · α
When c · (Tci + Tco) / 2, it is assumed that the gap t _ci between the refractory crucible 11a and the inductively heated member 11b at room temperature has a relation of 0.5 · t _ci ≦ t ₀ ≦ 2.0 · t _ci .

The high-frequency induction heating coil 12 is made of a Cu pipe having a diameter of φ12 mm in which cooling water circulates. The high-frequency induction heating coil 12 has five turns, an inner diameter of φ120 mm and a height h110 mm. Oscillation frequency 100 kHz, output 60 kW
The two high frequency power supplies 20 are installed outside the vacuum chamber 2 and connected to two high frequency induction heating coils 12 disposed inside the vacuum chamber 2 through a high frequency feeder 21 and a vacuum feedthrough (not shown). . The high-frequency feeder 21 is 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 high-frequency induction heating coil 12
Is preferably in a shape corresponding to the side surface of the refractory crucible 11a.

Further, the evaporation chamber 9 is located between the cooling can 4 and the evaporation source assembly 11 having the magnetic material 10,
A cylindrical wall (hereinafter referred to as a vapor diffusion preventing wall) 15 is provided as a means for preventing the diffusion of the vapor so that the peripheral wall surrounds a path through which the vapor flow generated by evaporation of the vapor passes. In the vicinity of the mask 4 and in the vicinity of the masks 13 and 14, a first gas inlet 17 for injecting an acidified gas or a mixed gas of an oxidizing gas and an inert gas toward the base film 3 is provided. ing.

The gas introduction unit 17 is located downstream with respect to the transport direction 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 that regulates the minimum incident angle (θmin). ing. The injection gas is O ₂
Gas was used. The injection 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). O ₂ gas is injected in a substantially oblique direction with respect to the scattering direction of the evaporating particles that have passed through the opening of the vapor diffusion preventing wall 15 described later by the O ₂ gas introduction from the gas introduction part 17, and a part of the evaporating metal particles To oxidize.

The inner peripheral wall surface of the vapor diffusion preventing wall 15 is formed of a high melting point metal, ceramics, or the like, and has a refractory crucible 11a.
Are arranged so as to constitute an evaporative vapor flow path surrounded by a regulating surface extending in a substantially vertical direction in a substantially continuous state, and the lower surface and the upper surface allow passage of evaporative particles of the magnetic material 10 and the directivity thereof. It has a cylindrical shape that is open to enhance and has only a peripheral wall, and the horizontal cross-sectional shape may be circular, elliptical, oval, square, rectangular, or any other shape. The vertical cross section is also square, rectangular, trapezoidal,
Any other shape may be used.

Further, the vapor diffusion preventing wall 15 is concentrically formed from the center of the opening toward the outside to form an inner wall portion 15a and an outer peripheral portion 15a.
c).

A heating structure including a heating source such as a resistance heater, a high-frequency induction heating coil or the like, or cooling water, liquid nitrogen, liquid helium, ethylene glycol is provided on the outer peripheral surface side of the vapor diffusion preventing wall 15. And the main body is made of Fe, Cu, Al, Ni, Ti, Mg, Z
A structure including a cooling structure formed of n, an alloy thereof, stainless steel, or the like can be employed.

The vapor diffusion preventing wall 15 is based on the center of the surface of the molten metal of the refractory crucible 11a. Evaporated particles of the magnetic material 10 that have evaporated from the reference point and jumped upward are subjected to the maximum incidence described later. It is configured so as not to prevent adhesion to a continuous range from the maximum incident angle θmax to the minimum incident angle θmin defined by the angle regulating mask 13 and the minimum incident angle regulating mask 14.

The refractory crucible 11a, the high-frequency induction heating coil 12, the high-frequency power supply 20, the high-frequency feeder 21 and the like are merely examples of the evaporation source assembly, and the base film 3 is moved in the width direction (the transport direction in the plane of the base film 3). In the case where the width of the evaporation source assembly 11 is large, the shape of the evaporation source assembly 11 is changed according to the width of the base film 3 (for example, the horizontal cross-sectional shape of the evaporation source assembly 11 is elliptical, When the width is wide, the major axis direction of the elliptical shape of the evaporation source assembly 11 is adjusted to the width direction of the base film 3), and a plurality of sets of the evaporation source assembly 11 are arranged corresponding to the width direction of the base film 3. A configuration can also be adopted. In this case, a plurality of sets of the evaporation source assembly 11 (including the refractory crucible 11a), the high-frequency induction heating coil 12, the high-frequency power supply 20, and the high-frequency feeder 21 are independently provided. It is also possible to adopt a configuration in which the high-frequency induction heating coil 12, the high-frequency power supply 20, and the high-frequency feeder 21 are provided in common.

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

First, the insides of the vapor deposition chamber 9 and the winding chamber 8 are evacuated by vacuum evacuation means (not shown), and the internal state of the vapor deposition chamber 9 and the winding chamber 8 is, for example, 5.0 × 10 ^−5.
A vacuum state of about 4.0 × 10 ⁻⁴ Torr is set. After the insides of the vapor deposition chamber 9 and the winding chamber 8 are made substantially vacuum as described above, electric power is supplied to the high-frequency induction heating coil 12 using the high-frequency power supply 20, whereby the magnetic material 10 of the evaporation source assembly 11 is discharged. Heat and evaporate.

The heating method of the magnetic material 10 is as follows: the conveying speed of the base film 3 is 80 m / min, and the oxygen introduction amount is 1000 cc / min.
Preliminary tests were conducted on the input power in a steady state sufficient to maintain the evaporation rate at which the film thickness was 800 angstrom under the above conditions and the holding time until the evaporation rate was obtained. The holding time means that after starting to supply a constant power, the temperature of the magnetic material 10 rises and melts, and until the entire evaporation source assembly 11 is heated sufficiently to reach a thermal equilibrium state until a constant evaporation rate can be maintained. Time.

After the elapse of the holding time, the base film 3 was transported from the delivery shaft 5 at a transport speed of 80 m / min and a tension of 8.0 kgf / min.
The base film 3 is fed with O _{2 in a} pretreatment chamber (not shown).
After performing a glow discharge treatment using gas, the cooling can 4
Transport the top. Then, the shutter device is driven to the "open" state, and at the same time, the injection amount 1000
After forming a Co—O magnetic thin film on the base film 3 while injecting O ₂ gas at cc / min, the film is wound around the winding shaft 6. After the formation of the metal magnetic thin film, the shutter device is set to the "closed" state, and at the same time, the injection of the O ₂ gas from the gas introduction unit 17 and the power supply from the high frequency power supply 20 are stopped to terminate the film formation.

After depositing the magnetic thin film on the base film 3, a mixture of a phosphoric acid-based lubricant + a perfluoropolyether lubricant and a rust inhibitor (benzotriazole) is dissolved and applied to the surface of the magnetic thin film. A non-magnetic powder containing carbon black as a main component, a mixed material of nitrocellulose, polyester, and polyurethane, and an isocyanate curing agent are dissolved and dispersed on the back surface, and applied with a thickness of 0.5 μm. As described above, the thin film of the magnetic material is deposited on the base film 3.

Here, the outer shape of the inductive heating member 11b is 110 mm.
Was fixed, and the test was performed by changing the inner diameter in various ways.

The evaluation method was as follows. Co. ₁₀₀ was collected as the magnetic material 10 in the refractory crucible 11a, and the vacuum chamber was evacuated to 5.0 ×
The magnetic material 10 was heated and melted by supplying a constant power of 10 KW to the high frequency induction heating coil 12 by the high frequency power supply 20 for 20 minutes while maintaining the pressure at 10 ^-5 Torr. After that, supply power becomes 0
It was left as KW for 20 minutes. This heating and standing operation was defined as one cycle, and heating and standing were repeated 5 times continuously. Then, disassemble the evaporation source assembly and refractory crucible 11
The occurrence of cracks and the outflow of the magnetic material 10 were observed.

In this test, the inner wall temperature Tci of the refractory crucible 11a of the evaporation source assembly was measured by measuring the molten metal surface with a radiation thermometer, and the temperature was estimated as the inner wall temperature of the refractory crucible. Where temperature

[0053]

(Equation 1)

The temperature of the outer wall of the refractory crucible 11a and the inner wall of the material to be heated are measured with a thermocouple.

[0055]

(Equation 2)

The outer wall temperature of the material to be heated was also measured with a thermocouple, and was found to be Tio = 1900K.

The test results are shown in Table 1 below.

[0058]

[Table 1]

As shown in Table 1, by providing an inductively heated member 11b on the outer periphery of the refractory crucible 11a, even if a crack occurs in the refractory crucible 11a, the molten magnetic material leaking from the crack is removed by the evaporation source assembly. It will not leak outside from 11. Further, the inner diameter of the induction-induced heating member 11b is 97.0 m.
When it is in the range of m to 100.0 mm, the occurrence of cracks can be greatly reduced.

The refractory crucible 11a and the induction heating member 11
When the gap with b is relatively large, the gap has a particle size of 0.3 m
The occurrence of cracks can be reduced by filling a powder material of m or less or winding a sheet-like member.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating an embodiment of an evaporation source assembly.

FIG. 3 is a diagram illustrating a configuration of a conventional magnetic recording medium manufacturing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum vapor deposition apparatus 2 Vacuum tank 3 Base film 4 Cooling can 5 Delivery axis 6 Winding axis 7 Partition plate 8 Winding chamber 9 Deposition chamber 10 Magnetic material 11 Evaporation source assembly 11a Refractory crucible 11b Induced heating member 11c Filling Material 12 High-frequency induction heating coil 13, 14 Mask 15 Wall for preventing vapor diffusion 17 First gas inlet 18 Mask opening

Claims (4)

[Claims] 1. A transport means for transporting a long substrate along a predetermined path in a vacuum atmosphere, an evaporation source of a magnetic material disposed below the predetermined path, and an outer side of the evaporation source. High-frequency induction heating means for evaporating the magnetic material by heating by high-frequency induction heating surrounding the evaporation source,
An apparatus for manufacturing a magnetic recording medium for forming a magnetic thin film on a substrate by depositing the vapor stream on the substrate while transporting the substrate, wherein the evaporation source is disposed between the evaporation source and the high-frequency induction heating means. Is provided, and the thermal expansion coefficient αc of the evaporation source and the thermal expansion coefficient αi of the guided heating member are αc.
> Αi, a magnetic recording medium manufacturing apparatus. 2. In the heating state of the evaporation source, the thermal expansion coefficient αc (1 / K) of the evaporation source, the outer diameter Dc (mm),
Inner wall surface temperature Tci (K), outer wall surface temperature Tco (K), coefficient of thermal expansion αi (1 / K) of the above-mentioned induced heating member, outer diameter D
i (mm), inner wall surface temperature Tii (K), outer wall surface temperature Ti
The relationship of o (K) is t ₀ = Di · αi · (Tii + Tio) / 2−Dc · α
When c · (Tci + Tco) / 2, the gap t _ci between the evaporation source and the induced heating member at room temperature has a relationship of 0.5 · t _ci ≦ t ₀ ≦ 2.0 · t _ci. Item 2. An apparatus for manufacturing a magnetic recording medium according to Item 1. 3. A metal, oxide, carbide or the like having a particle size of 0.3 mm or less is provided in a gap between the evaporation source and the induced heating material.
3. The apparatus for manufacturing a magnetic recording medium according to claim 1, wherein a powdery filler comprising at least one of a nitride and a boride is filled. 4. The magnetic recording medium according to claim 1, wherein a gap between the evaporation source and the induction-heated material is filled with a heat-resistant member having a melting point of 1600 K or more. apparatus.