JP2000322738A - Apparatus for production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of thermal vulnerability which is the drawback of high-frequency induction heating with an apparatus for production of a magnetic recording medium forming magnetic layers of multilayered constitution. SOLUTION: The magnetic layers are deposited by evaporation on a base film 3 by heating the magnetic material 10 in an evaporation vessel 16 by a high-frequency induction heating coil 12. The base film 3 is irradiated with an electron beam 31 emitted from an electron beam irradiation source 30 prior thereto. As a result, charges are accumulated on the film 3. The film 3 is brought into tight contact with a cooling can 4. The heat by vapor deposition is allowed to escape well to the cooling can 4 and the thermal vulnerability 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 an apparatus for manufacturing a magnetic recording medium, and more particularly, to a method for heating and melting a metal material to evaporate the metal material and depositing the vapor stream on a base material such as a base film. The present invention relates to an apparatus for manufacturing a magnetic recording medium on which a 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 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 applying a base film (base material) made of a polyolefin such as polyester or polypropylene and thereafter curing or drying the base film is widely known.

On the other hand, in recent years, there has been an increasing demand for higher recording densities. As a result, the density of the magnetic material in the magnetic layer of the magnetic recording medium has increased, the coercive force has increased, and the frequency characteristics have shifted to shorter wavelengths. Alternatively, improvements such as a thinner magnetic layer have been made. However, in a coating type tape, since the binder remains in the magnetic layer, it has become 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, a magnetic layer can be formed by directly depositing and growing a magnetic material on a base material without using a binder, thereby increasing the packing density of the magnetic material in the magnetic layer, The thickness of the layer can also be reduced.

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.

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.
Has a cylindrical shape inside a vacuum chamber 2 in a substantially vacuum state, and a polyester film on the outer peripheral surface of the cylinder.
A cooling can 4 for winding a long base film 3 made of a non-magnetic material such as a polyamide film or a polyimide film in the longitudinal direction is provided. The base film 3 conveyed to the winding shaft 6 side is conveyed on the outer peripheral surface of the cylinder.

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 container 16 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. The particles of the magnetic material 10 (referred to as magnetic particles or evaporating particles), which are vapor flows and evaporate upward, are conveyed in the direction of arrow Y with the rotation of the cooling can 4.
Is continuously vapor-deposited on the surface of the substrate to form a magnetic layer.

Here, in order to efficiently deposit the evaporated magnetic material particles on the base material and increase the vapor deposition efficiency, it is sufficient to prevent the evaporated particles from being diffused widely. According to the technology disclosed in JP-A-204513 and JP-A-2-56730, between the evaporation source and the cooling can, a portion around which the evaporated particles pass is surrounded by a peripheral wall, and the flow path is formed. For example, a cylindrical vapor diffusion preventing wall 15 may be provided to regulate the air.

When such a vapor diffusion preventing wall 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 a trajectory of the electron beam from the electron gun to the magnetic material 10 placed in the evaporation container 16,
This is because if the vapor diffusion preventing wall 15 is provided above the electron beam 16, it is difficult to secure the passage of the electron beam. Therefore, high frequency induction heating means is usually used as the heating means.

It has been found that it is effective to introduce oxygen during the vapor deposition in order to improve the coercive force of the formed magnetic thin film. The method of introducing this oxygen is
Usually, a gas introduction unit 17 is provided near the mask 14 located on the downstream side in the transport direction of the base film 3, and the oxidizing gas such as oxygen is blown to the evaporated particles of the magnetic material 10. ing. For example, according to the technique disclosed in Japanese Patent Publication No. 2-27732, an oxygen gas is introduced from the vicinity of the minimum incident angle, and an inert gas is also introduced from the vapor deposition start side (the maximum incident angle side). The physical filling factor and the magnetic filling factor are adjusted.

[0012]

In the above-described method of heating an evaporation source by an electron beam, it is necessary to secure a trajectory for irradiating the electron beam into an evaporation container as an evaporation source. The base film cannot be brought close to the base film, and it is necessary to provide a certain space. The space between the evaporation container and the base film is preferably small from the viewpoint of improving the vapor deposition efficiency. On the other hand, in the method of heating the evaporation source by high-frequency induction heating, since the evaporation source can be provided close to the base film, the evaporation efficiency can be improved as compared with the method using an electron beam.

However, although high-frequency induction heating can improve the vapor deposition efficiency as compared with the method using an electron beam, it has a drawback that heat loss easily occurs.
Here, the term "heat loss" refers to wrinkles of a substrate (base film) generated at the time of vapor deposition, which are generated by thermal factors such as latent heat of evaporated particles and radiant heat from an evaporation container. Normally, the cooling can is cooled to about -30 ° C, and the substrate that comes into uniform contact with the surface is the heat that enters when the magnetic material adheres (the latent heat of the evaporated particles and the radiant heat from the evaporation source and scene). Is escaped to the cooling can side, whereby the temperature rise of the self 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 base material is generated (both front and back surfaces of the base material) as the temperature rises, and it becomes more difficult for heat to escape, so that the temperature of the base material rises. On the other hand, since a tension is applied to the base material in the transport direction, a portion where the base material is softened due to a rise in the temperature of the base material is elongated, and wrinkles are generated. The generation of this wrinkle is heat loss.

In view of the above circumstances, an object of the present invention is to provide an apparatus for manufacturing a magnetic recording medium capable of preventing heat loss, which is a drawback of high-frequency induction heating.

[0015]

According to the present invention, there is provided an apparatus for manufacturing a magnetic recording medium, comprising: conveying means for conveying a long flexible substrate along a predetermined path in a vacuum atmosphere; A magnetic material evaporation source disposed below, high-frequency induction heating means outside the evaporation source and being heated by high-frequency induction heating surrounding the evaporation source to evaporate the magnetic material; and Cooling means for cooling the substrate on the predetermined path, provided opposite to the evaporation source, and by vapor-depositing the vapor stream on the substrate while transporting the substrate. An apparatus for manufacturing a magnetic recording medium for forming a magnetic thin film on a base material, comprising: before forming the magnetic thin film on the base material, an electron beam irradiation unit having an electron beam source for irradiating the base material with an electron beam. It is characterized by having.

In the apparatus for manufacturing a magnetic recording medium according to the present invention, it is preferable that the electron beam irradiation unit is provided to face the cooling unit with the base material interposed therebetween. Thus, the deposition of the magnetic material is performed subsequent to the irradiation of the base material with the electron beam.

Preferably, the cooling means has a metal transfer surface.

Here, the metal transfer surface may be a rotary drum having a mirror-polished surface, or an endless belt-shaped metal plate capable of forming a predetermined slope with respect to the evaporation source.

Further, the acceleration voltage V ₀ (k
V) is preferably in the range of -8.0 ≦ V ₀ ≦ −1.0, and the irradiation current J ₀ (mA / cm ² ) per unit area of the base material during irradiation with the electron beam is preferably , 1 × 10
It is preferably in the range of ^-2 ≦ J ₀ ≦ 1.0 × 10 ⁻¹ .

Further, it is preferable that the apparatus further comprises a static eliminator for performing static elimination of the substrate after the magnetic thin film is formed on the substrate.

In this case, it is preferable that the charge removing section has means for injecting an inert gas onto a surface of the substrate opposite to the surface on which the magnetic thin film is formed. The active gas is Ar, O ₂ , Kr, Xe, Rn
Is preferably at least one of

[0022]

According to the apparatus for manufacturing a magnetic recording medium of the present invention, the base material is irradiated with an electron beam before the formation of the magnetic thin film. Will remain. Thereby, a Coulomb force acts between the space charge and the opposing 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.

On the other hand, when the base material is peeled off from the cooling means after the formation of the magnetic thin film on the base material, wrinkles may occur due to the good adhesion between the base material and the cooling means. Therefore, the surface opposite to the surface on which the magnetic thin film is formed of the base material is subjected to a static elimination process such as exposure to glow discharge plasma, thereby preventing wrinkles when the base material is peeled off from the cooling means. can do.

At this time, the static elimination section is provided with means for injecting an inert gas such as Ar onto the surface opposite to the surface on which the magnetic thin film is formed, so that the space existing in the base material is provided. The charge can be removed, which can also prevent the occurrence of wrinkles when peeling the substrate.

[0025]

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

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 width is 220 μm and the length is 3000
m and a thickness of 6 μm are 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 diameter is 14 μm and the density is 50.
It was set to one million / 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 before being wound around the cooling can 4.

The base film 3 is wrapped around the winding 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 when the cooling can 4 rotates in the arrow Y direction. For example, it is conveyed at a speed of 10 to 100 m / min, and is wound on a winding shaft 6. The cooling can 4 has a diameter of 60
It is a cylindrical drum of 0 mm and 400 mm width, the surface of which is hard chrome plated, mirror polished to 0.8 S or less, and has a structure in which cooling water and other refrigerant (ethylene glycol) are circulated. For example, it is maintained at −35 to + 25 ° C. (−28 ° C. in the present embodiment).

At the position immediately after the base film 3 is wound around the cooling can 4, the electron beam irradiation source 30 is located at a position facing the cooling can 4 and 450 mm away from the cooling can 4.
Are arranged. The electron beam irradiation source 30 has an acceleration voltage of -12.0
kV to -0.5 kV and an output current of 0.5 mA to 80 mA, and the irradiation area of the base film 3 is in a range of a square of 200 mm × 200 mm. Further, at a position immediately after the electron beam irradiation position on the base film 3, a charge meter 32 is provided to measure the charged position of the base film 3.

The surface of the cooling can 4 is separated from the cooling can 4 by a distance of 3 mm, and cooling water of 18 ° 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 11, which will be described later, and the line segment from the center of the 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 °. Masks 13 and 14
The opening width of the mask opening 18 in the width direction (the direction perpendicular to the transport direction of the base film 3) is set to 150 mm.

The front surfaces of the masks 13 and 14 have a curved shape along each of the masks 13 and 14.
And has a function of preventing evaporated metal particles of the magnetic material 10 from adhering to the surface of the base film 3, circulating cooling water of 18 ° C. inside, and
4 is provided with a movable shutter device (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 blown from the outside of the vacuum chamber 2 to the vapor deposition chamber 9, the pressure in the chamber and the partial pressure of various residual gases such as H ₂ O and O ₂ are constantly adjusted by adjusting means (not shown). Is done.

In the vicinity of the cooling can 4 and the mask 1
In the vicinity of 3 and 14, a gas introduction unit 17 for blowing a mixed gas of an acidifying gas or an oxidizing gas and an inert gas toward the base film 3 is provided.

The gas introducing section 17 is located downstream of the cooling can 4 with respect to the transport direction of the base film 3 and is near the mask 14 that regulates the minimum incident angle (θmin) on the surface of the mask 14 on the cooling can 4 side. Built in. Note that O ₂ gas was used as the injection gas. The spray direction of the gas spray slit defines the minimum angle of incidence (θmin).
The direction is substantially parallel to the tangent line on the cooling can 4 at the upper reference point. O ₂ gas is ejected in a substantially oblique direction with respect to the scattering direction of the evaporated particles that have passed through the opening of the vapor diffusion preventing wall 15 described later by the introduction of the O ₂ gas from the gas introduction unit 17 and a part of the evaporated metal particles. To oxidize.

Further, the winding film 8 contains the base film 3.
A glow discharge processing unit 33 for post-processing is provided. Further, the 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 16.

In the vapor deposition chamber 9, below the cooling can 4, there is provided an evaporation container 16 containing the magnetic material 10. Evaporation vessel 16
A high-frequency induction heating coil 12 for heating the magnetic material 10 is provided around the periphery. Further, a high-frequency power supply 20 for supplying high-frequency power to the high-frequency induction heating coil 12 is provided.
A high-frequency power supply feeder 21 for transmitting high-frequency power to the high-frequency induction heating coil 12 is 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.

As the magnetic material 10, for example, Fe, Co,
Ni, CoNi, FeCo, FeCu, FeCr, Co
Cr, CoCu, CoAu, CoPt, CoW, NiC
r, CoV, MnBi, MnAl, CoFeCr, Co
NiCr, CoRh, CoNiPt, CoNiFe, C
The magnetic material 10 is appropriately selected from ferromagnetic metals and ferromagnetic alloys such as oNiFeB, FeCoNiCr, and CiNiZn.

The magnetic material 10 which is a component of the evaporation container 16
Is made of, 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 11 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. , Rectangular, trapezoidal, or any other shape. In the present embodiment, the refractory crucible 11 has a cup shape (inner diameter φ80 mm, outer diameter φ96 mm, height 100 mm,
(Internal depth is 90 mm) and the material is Y ₂ O ₃ stabilized ZrO ₂
(Chemical component (wt%) ZrO ₂ ; 88.0-95.0%, Y ₂ O
₃ ; 5.0 to 12.0%). Also, magnetic materials for evaporation
Co ₁₀₀ was used as 10.

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 six turns, an inner diameter of φ120 mm, and a height h105 mm. Oscillation frequency 200 kHz, output 60 kW
The high frequency power supply 20 was installed outside the vacuum chamber 2 and connected to a high frequency induction heating coil 12 disposed inside the vacuum chamber 2 through a high frequency feeder 21 and a vacuum feedthrough (not shown). The high frequency power supply 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
It is preferable to make the shape corresponding to the side surface of the refractory crucible 11.

Further, the path between the cooling can 4 and the evaporating vessel 16 provided with the magnetic material 10 and through which the vapor flow generated by the evaporation of the magnetic material 10 passes, is formed such that the peripheral wall thereof surrounds the vapor diffusion. A vapor diffusion preventing wall 15 is provided as a means for preventing the occurrence of the gas diffusion.

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 forms a vapor flow path surrounded by a regulating surface extending substantially vertically in a state substantially continuous with the refractory crucible 11. The lower surface and the upper surface are cylindrical so as to allow the passage of the evaporated particles of the magnetic material 10 and to improve the directivity thereof, and have a cylindrical shape having only a peripheral wall. It may be oval, oval, square, rectangular, or any other shape. The vertical cross-section may also be square, rectangular, trapezoidal, or any other shape.

Further, the vapor diffusion preventing wall 15 is composed of two layers of an inner wall portion 15a and an outer peripheral portion 15c concentrically from the center of the opening toward the outside.

The inner wall portion 15a of the vapor diffusion preventing wall 15 is a cylindrical (inner diameter φ50 mm, outer diameter φ72 mm, height h95 mm) Ca
O-stabilized ZrO ₂ (chemical component (wt%) 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 has a cylindrical shape (inner diameter φ72 mm, outer diameter φ120 mm, height h95 mm), circulates cooling water at 18 ° C. inside, and has a main body made of oxygen-free copper. Was used.

Next, the operation of the magnetic recording medium manufacturing apparatus according to 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 state inside the winding chamber 8 is, for example, 5.0 × 10 ⁻⁵ to
A vacuum state of 4.0 × 10 ⁻⁴ Torr is set. In addition,
In this embodiment, it is set to 5.0 × 10 ⁻⁵ Torr. Vapor deposition chamber 9
After the inside of the winding chamber 8 is evacuated as described above, power is supplied to the high-frequency induction heating coil 12 using the high-frequency power supply 20 for the evaporation container 16, whereby the high-frequency induction heating coil 12 generates heat. The magnetic material 10 in the evaporation container 16 is 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.
It is delivered under the conditions of a transport speed of 60 m / min and a tension of 6.0 kgf / 220 mm, and is transported on the cooling can 4.

In a state in which the base film 3 is wound and transported on the cooling can 4, the electron beam irradiation source 30 is operated, and the electron beam 31 is pulled in and out of the coil, so that the 200 mm An electron beam 31 is uniformly applied to a range of × 200 mm. At this time, the acceleration voltage of the electron beam irradiation source 30 is changed in the range of -12.0 kV to -0.5 kV, and the emission current is changed in the range of 0.5 mA to 80 mA. The charge position of the base film 3 is measured by the charge meter 32. Further, the state of occurrence of heat loss after forming a magnetic thin film described later is observed.

Then, the shutter device is driven to open.
State. At the same time, spray amount 450 cc from gas inlet 17
A first Co-0 magnetic thin film (700 Å thick) is formed on the base film 3 while blowing O ₂ gas at a rate of / min. The output of the high frequency power supply 20 at this time is 20k
W.

The base film 3 after forming the magnetic layer
In the glow discharge processing section 33, the back surface of the base film 3 is subjected to glow discharge processing. In the glow discharge processing procedure, Ar gas is blown at a flow rate of 50 cc / min to the glow discharge processing section 33, and the inside of the glow discharge processing section is maintained at a degree of vacuum of 8.0 × 10 ⁻³ Torr. DC power (−360
VDC, 1.2 A) to generate glow discharge.
By generating the glow discharge in this way, it is possible to prevent wrinkles from occurring when the base film 3 is peeled off from the transfer surface of the cooling can 4. Also, wrinkles can be prevented from occurring only by introducing Ar gas, for example, at 50 cc / min, instead of glow discharge.

Thereafter, the base film 3 is wound on a winding shaft 6. After continuously forming a 3000 m long metal magnetic thin film, the shutter device is set to the "closed" state, and at the same time, the O ₂ gas is blown from the gas inlet 17 and the power supply from the high frequency power supply 20 is stopped to form a film. Finished.

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 and dried. The above process was performed by changing the output of the high frequency induction heating coil 12 variously to obtain a raw material on which a magnetic thin film was formed, and the raw material was cut into a width of 8 mm to prepare a magnetic recording medium for evaluation.

The following evaluation of heat loss was performed.

[Method of Evaluating Heat Loss] The state of heat loss was visually observed on the front surface side by irradiating visible light from the back surface of the vapor-deposited raw material having a width of 220 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 were as follows: a double circle indicates no heat loss, a circle indicates no heat loss ± 40 mm from the center in the base width direction, and a continuous heat loss (longitudinal direction) Is not recognized, but the heat loss caused by itself is less than 10 places. The continuous heat loss is not recognized, but the heat loss caused alone is not recognized.
△ ×, heat loss continuously in 10 or more places (longitudinal direction)
(Having a length of 20 mm or more) was evaluated as x, and the one constantly wrinkled due to heat loss was evaluated as xx.

FIG. 2 shows the emission current (output current) of the electron beam 31 using the acceleration voltage of the electron beam irradiation source 30 as a parameter.
FIG. 4 is a diagram illustrating a relationship between the position of the base film and the charge position of the base film (base charge position) at a position immediately after electron beam irradiation. For example, when the acceleration voltage of the electron beam irradiation source 30 is -8 kV, the base charge potential becomes the maximum at -740 V when the emission current is 20 mA. Thereafter, even if the emission current is increased, the base charge potential decreases, and at 50 mA or more, the base charge potential fluctuates greatly over time and becomes unstable. Focusing on the accelerating voltage, in the range of -8 kV to -0.5 kV, the base charge potential increases with an increase in the accelerating voltage.
At 0 kV, the voltage becomes lower than -8 kV, and the base charge potential fluctuates greatly, resulting in an unstable state.

Observation of the relationship between the electron beam irradiation conditions and the base charge and the occurrence of heat loss showed a correlation between the base charge and the occurrence of heat loss as shown in Table 1 below. It turned out that there was.

[0059]

[Table 1]

As a result, it was found that under the condition that the base charge was negatively charged from -200 V, there was an effect of suppressing the occurrence of heat loss. At this time, the limit of the emission current was 4 mA (1.0 × 10 ⁻² mA / cm ² ). As a more desirable range, a condition in which the negative charge is more than -400V is preferable. As shown in FIG. 2, when the emission current is 50 mA or more, the charging state becomes unstable. Therefore, the upper limit is 40 mA (1.0 × 10 ⁻¹ mA / cm ² ). A desirable range is 10 mA to 30 mA when the acceleration voltage is in the range of -8 kV to -1 kV.

Regarding the acceleration voltage, in the case of -0.5 kV,
-200V base charge potential even when emission current is changed
Therefore, the effect of suppressing heat loss cannot be expected. When the acceleration voltage is in the range of -1 kV to -8 kV, the emission current is 4 mA (1.0 × 10 ^-2 mA / c).
m ² ) to −40 mA (1.0 × 10 ⁻¹ mA / cm ² ).
It can be charged more negatively than kV and heat loss can be suppressed. However, at -10 kV, it was found that the base charged position became unstable, and the adhesion between the base film 3 and the transfer surface of the cooling can 4 changed, and wrinkles were likely to occur.

[Brief description of the drawings]

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

FIG. 2 shows an acceleration voltage of an electron beam irradiation source as a parameter.
Diagram showing the relationship between the emission current (output current) of an electron beam and the charge potential (base charge potential) of a base film at a position immediately after electron beam irradiation.

FIG. 3 is a diagram showing 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 Refractory crucible 12 High frequency induction heating coil 13, 14 Mask 15 Vapor diffusion Prevention wall 17 Gas inlet 18 Mask opening 30 Electron beam irradiation source 31 Electron beam

Claims (8)

[Claims] 1. A transport means for transporting a long flexible base material along a predetermined path in a vacuum atmosphere, an evaporation source of a magnetic material disposed below the predetermined path, A high-frequency induction heating means outside the source and heated by high-frequency induction heating surrounding the evaporation source to evaporate the magnetic material,
Cooling means for cooling the base material on the predetermined path, provided to face the evaporation source with the base material interposed therebetween; and In a magnetic recording medium manufacturing apparatus for forming a magnetic thin film on the substrate by vapor deposition, an electron beam source having an electron beam source for irradiating the substrate with an electron beam before forming the magnetic thin film on the substrate. An apparatus for manufacturing a magnetic recording medium, comprising: a line irradiation unit. 2. The apparatus for manufacturing a magnetic recording medium according to claim 1, wherein the electron beam irradiation unit is provided to face the cooling unit with the base material interposed therebetween. 3. An apparatus according to claim 1, wherein said cooling means has a metal transfer surface. 4. An acceleration voltage V ₀ (kV) of the electron beam source.
4. The apparatus for manufacturing a magnetic recording medium according to claim 1, wherein a _{value of} −8.0 ≦ V ₀ ≦ −1.0 is satisfied. 5. An irradiation current J ₀ (mA / cm ² ) per unit area of the substrate during irradiation with the electron beam is 1 ×
^{5. The} apparatus for manufacturing a magnetic recording medium according to claim ¹ , wherein the range is 10 ^-2 ≤J ₀ ≤1.0 × 10 ^-1 . 6. The magnetic device according to claim 1, further comprising a static eliminator for performing a static elimination process on the substrate after the magnetic thin film is formed on the substrate. Manufacturing equipment for recording media. 7. The device according to claim 6, wherein the static elimination unit has means for injecting an inert gas onto a surface of the substrate opposite to a surface on which the magnetic thin film is formed. Equipment for manufacturing magnetic recording media. 8. The inert gas includes Ar, O ₂ , Kr,
8. The apparatus for manufacturing a magnetic recording medium according to claim 7, wherein the apparatus is at least one of Xe and Rn.