JPH10162359A - Device for manufacturing magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise a vapor deposition efficiency of a material, to reduce dust in a vacuum device, to enable reducing cleaning frequency in the device and further to greatly improve productivity of magnetic recording media excellent in magnetic characteristics. SOLUTION: Two cooling can rolls 21, 22 for respectively running two nonmagnetic base bodies 23, 24 are provided and are placed side by side so that the rotation axes thereof are parallel to each other and have a fine gap L therebetween. Further, a vaporization source 25 of the magnetic material is disposed at central lower part between the two cooling can rolls, the maximum incident angle θmax1 of a vapor stream from the vaporization source to the first nonmagnetic base body 23 is regulated by the second nonmagnetic base body 24 and the maximum incident angle θmax2 of the vapor stream to the second nonmagnetic base body 24 is regulated by the first nonmagnetic base body 23.

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 an apparatus for forming a magnetic material on a non-magnetic substrate by oblique deposition.

[0002]

2. Description of the Related Art The recording density of a magnetic tape has been rapidly increased in recent years. In this process, magnetic tapes have shifted to high-performance iron oxide tapes, metal tapes, and thin film tapes having high coercive force and high magnetic flux density. As an application of this magnetic tape, in the field of VTRs, a thin film tape is particularly noted in the future in order to achieve digitization and high definition.

As this thin film tape, a so-called evaporation tape in which a magnetic film is formed by an oblique evaporation method has been put to practical use. Specifically, a magnetic material such as Co or CoNi in a crucible is irradiated in a vacuum with an electron beam using a pierce-type electron gun to melt and evaporate these materials and introduce oxygen. It is manufactured by forming a thin film made of CoO and CoNiO on a base film such as PET, PEN, PI (polyimide) and PA (polyamide).

FIG. 2 shows a general film forming apparatus using this oblique evaporation method. In FIG. 2, an unwinding roll 2, a take-up roll 3, guide rolls 4, 5 and a cooling can roll 7 are arranged in a vacuum chamber 1, and a non-magnetic substrate, that is, a base film 6 is interposed between these rolls. Is wound, and travels in the direction of the arrow in the figure from the unwinding roll 2 to the winding roll 3. A cooling device (not shown) is provided inside the cooling can roll 7 to prevent deformation of the base film 6 due to a rise in temperature during vapor deposition on the base film 6.

[0005] A crucible 8 containing a magnetic material 11 is disposed below the cooling can roll 7. A heating device for melting and evaporating the magnetic material 11 is provided on the side wall of the vacuum chamber 1, for example. , A pierce-type electron gun 12 is provided. Further, masks 9 and 10 are disposed in the vicinity of the outer peripheral surface of the cooling can roll 7, and the mask 9 allows the maximum incident angle θ of the vapor flow of the magnetic material to the base film 6.
_max is regulated, and the minimum incident angle θ
_min is regulated. Then, while the base film 6 is running on the outer peripheral surface of the cooling can roll 7, the evaporated magnetic material is deposited in a range of the maximum and minimum incident angles set at a predetermined angle (this range is referred to as a vapor deposition opening). The magnetic film adheres to the surface of the base film 6 to form a magnetic film. At this time,
The magnetic properties of the obtained magnetic film are determined by the maximum incident angle θ _max and the minimum incident angle θ _min of the vapor flow of the magnetic material. Generally, the maximum incident angle θ _max = 90 ° and the minimum incident angle θ _min =
It is set to 40 °.

The electron beam 13 emitted from the pierce-type electron gun 12 is controlled by a deflection magnet 1 which is arranged close to the crucible 8 and applies a deflection magnetic field in the trajectory of the electron beam 13.
4 and the deflection magnet 15 in the electron gun 12. The irradiation position of the electron beam 13 is at the center of the crucible 8,
Scanning is performed at a predetermined cycle in the width direction of the base film 6, and the magnetic material 11 in the crucible 8 is dissolved and evaporated. Also,
There is also a method in which the straight electron beam emitted from the electron gun 12 is scanned in the crucible 8 using only the deflection magnet 15 in the electron gun 12 without installing a deflection magnet close to the crucible 8.

[0007]

However, in the above-described oblique deposition method, the magnetic characteristics of the formed magnetic film largely depend on the incident angle, and when the deposition opening is widened, the magnetic characteristics are significantly deteriorated. Therefore, there is a limit to the size of the evaporation opening. For this reason, there is a problem that the amount of the magnetic material adhering to the base film with respect to the total amount of the magnetic material used, that is, the so-called evaporation efficiency is low, and the productivity is very poor. Further, if the vapor deposition is performed for a long time, the evaporating magnetic material is deposited on the masks 9 and 10, and the dimensions of the masks 9 and 10 are changed to change the incident angle. As described above, when the incident angle changes, the magnetic characteristics of the magnetic film also change, so that a magnetic recording medium having predetermined magnetic characteristics cannot be produced for a long time.

In particular, the dimensional change of the mask 9 that regulates the maximum incident angle θ _max is serious because it has a large effect on magnetic characteristics. In order to prevent this, conventionally, the deposits on the mask 9 are periodically removed, but this is done by once releasing the vacuum in the apparatus and suspending the heating of the crucible to perform the work. There is a problem that production efficiency is significantly reduced,
Improvement is strongly desired. Further, since the vapor flow wraps around, for example, behind the mask 9 and adheres to the inner wall and the deposition-preventing plate in the apparatus, dust is scattered in the apparatus due to peeling of the adhered film, thereby causing tape dropout. Similarly, it was necessary to clean the inside of the apparatus by interrupting the process.

[0009]

The inventor of the present invention has conducted various studies to solve the above-mentioned problems. As a result, instead of installing one cooling can roll as in the conventional apparatus, two inventors have been required. If the cooling can rolls are arranged very close to each other and the evaporation source is placed at the lower center, the evaporation opening is substantially doubled, and the two non-magnetic substrates are simultaneously and simultaneously. We have obtained the idea that both deposition efficiency and production efficiency can be improved because deposition can be performed once under conditions.

That is, according to the present invention, there is provided an apparatus for manufacturing a magnetic recording medium for forming a magnetic film by depositing a vapor flow from an evaporation source of a magnetic material on a non-magnetic substrate by oblique evaporation. And two cooling can rolls for running the second non-magnetic substrate, respectively,
These cooling can rolls are arranged in parallel so that their respective rotation axes are parallel to each other, and with a minute gap, and the evaporation source is disposed at a lower center portion between the two cooling can rolls, The maximum incident angle of the vapor flow from the evaporation source to the first non-magnetic substrate is regulated by the second non-magnetic substrate, and the second flow of the vapor flow from the evaporation source is controlled by the second non-magnetic substrate.
Provided such that the maximum angle of incidence on the non-magnetic substrate is regulated by the first non-magnetic substrate. In the above configuration, the minute gap between the two cooling can rolls is preferably 3 mm or less.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of the structure of a film forming apparatus as an apparatus for manufacturing the above magnetic recording medium. In the drawing, the same components as those in FIG. 2 are denoted by the same reference numerals. The two cooling can rolls 21, 2
2 are arranged side by side so that their rotation axes are parallel to each other and their respective end faces are flush with each other, and an extremely small gap is formed at a position where the outer peripheral surfaces of the two cooling can rolls 21 and 22 are closest to each other. That is, the distance L is provided. On the upper part of the cooling can roll 21, an unwinding roll 31, a winding roll 32,
Guide rolls 41 and 42 are provided, and a non-magnetic substrate, for example, a base film 23 is wound between these rolls, and runs in the direction indicated by the arrow in the figure. On the other hand, an unwinding roll 33, a take-up roll 34, and guide rolls 43 and 44 are also provided above the cooling can roll 22, and a non-magnetic substrate such as the base film 24 is wound between these rolls. It turns and travels in the direction indicated by the arrow in the figure. That is, in the cooling can roll 21, the base film 23 runs clockwise, and in the cooling can roll 22, the base film 24 runs counterclockwise.

Below the cooling can rolls 21 and 22,
Masks 51 and 52 are provided to regulate the minimum incident angles θ _min1 and θ _min2 of the vapor flow from the magnetic material evaporation source 25 to the base films 23 and 24, respectively. Further, a magnetic material evaporation source 25 of a magnetic material is accommodated in a lower center portion between the cooling can rolls 21 and 22. In this configuration, the magnetic material is evaporated by irradiating the electron beam 13 from the electron gun 12 to the magnetic material evaporation source 25 in the crucible 8. At this time, the density of the steam flow from the crucible 8 depends on the traveling direction of the steam flow. Specifically, the normal direction of the crucible (directly above the crucible) is the largest, and the density decreases as the distance from the normal direction increases. In general, the angle distribution Φ of the steam flow density
(Θ) is represented by the following equation (1).

[0013]

Φ (θ) = Φ (0) cos ⁿ θ (1) where Φ (0): vapor flow density in the normal direction θ: angle (°) with respect to the normal direction n = 1 to 3 integer

Therefore, in the device shown in FIG.
In order to improve the vapor deposition efficiency, the vapor flow directed in the crucible normal direction may be effectively attached to the non-magnetic substrates 23 and 24. Therefore, the steam flow has two cooling can rolls 21,
It is necessary to prevent the gap from passing through the gap 22. The smaller the distance L of the gap, the better. In particular,
Although it depends on the degree of required characteristics for the magnetic recording medium to be manufactured, it is preferable that L = 3 mm or less. L is 3mm
If the pressure exceeds the limit, the steam may enter the traveling room and adhere to the inner wall and the guide roll, which may require cleaning or may cause a traveling obstacle. Further, since the vapor flow in the normal direction of the crucible becomes the vapor flow at the maximum incident angle with respect to the base films 23 and 24 running on the respective cooling rolls 21 and 22, the vapor flow at the maximum incident angle is applied to the base films 23 and 24. Before adhering to the base film 23, if the steam that has passed through the gap between the cooling can rolls 21 and 22 and entered the traveling chamber has already adhered to these base films 23 and 24,
In some cases, desired magnetic characteristics cannot be obtained.

The maximum incident angle θ _max1 of the steam flow on the cooling can roll 21 is regulated by the base film 24 running on the adjacent cooling can roll 22, and conversely, the maximum incidence of the steam flow on the cooling can roll 22. The angle θ _max2 is regulated by the base film 23 running on the adjacent cooling can roll 21. That is, since the maximum incident angle, which greatly affects the magnetic characteristics of the magnetic recording medium, is controlled not by the fixed mask but by the running base film, the evaporating magnetic material is deposited on the fixed mask as in the related art. No dimensional change occurs. Therefore, the incident angle does not change due to the dimensional change of the mask, and as a result, a magnetic recording medium having predetermined characteristics can be produced for a long time.

Further, in order to increase the production efficiency, it is necessary to simultaneously start and end the film formation on the base films 23 and 24 running on the two cooling can rolls 21 and 22, respectively. For this purpose, the amount of evaporation to each cooling can roll must be the same, and specifically, the crucible 8 of the two cooling can rolls 21 and 22
Must be identical in geometry. That is, θ _min1 = θ _min2 and θ _max1 = θ _max2 , and this is achieved by disposing the crucible 8 at the lower center of the two cooling can rolls 21 and 22.

[0017]

The present invention will be described in detail with reference to the following examples. <Embodiment> The apparatus shown in FIG.
By using the two cooling can rolls 21 and 22 of mm, the position (X, Y) (mm) of the crucible 8 and the distance L (mm) between the cooling can rolls 21 and 22 shown in FIG. And while introducing oxygen, length 1,000m, width 30
A 0 mm PET film was run on each cooling can roll, and a CoO magnetic film was deposited on the film to a thickness of 0.2 μm. Further, the incident angle of the vapor flow was one condition common to each cooling can roll, and the maximum incident angle was 90 ° and the minimum incident angle was 40 °.

At this time, the change in the deposition efficiency and the C
The Hc of the oO magnetic film and the state of adhesion to the guide roll and the inner wall of the traveling room were examined, and the results are shown in Table 1. Hc was measured at a film feed of 100 m and 900 m from the start of film formation. Further, the vapor deposition efficiency is as follows: (C attached to the film
Total amount of oO / total use amount of Co) × 100 (%), and each amount was determined as follows.

[0019]

## EQU2 ## The total amount of CoO adhered on the film: 1,000 m × 300 mm × 0.2 μm × 8.9 g / cm ³ (Co density)
× 2 = 10.6 kg Total amount of Co used: Co supply-(Crucible weight at the start of film formation-Crucible weight at the end)

[0020]

[Table 1]

<Comparative Example> The position (X, Y) (mm) of the crucible and the maximum incident angle θ were determined using the conventional apparatus shown in FIG. 2 and a cooling can roll 7 having a diameter of 1,000 mm.
Mask 9 and cooling can roll 7 that regulate _max = 90 °
The CoO magnetic film was deposited on a PET film having a length of 1,000 m and a width of 300 mm so as to have a thickness of 0.2 μm while introducing oxygen while changing the distance t (mm) of the film in various ways. Maximum incident angle θ _max = 90 when depositing a vapor stream
° and the minimum incident angle θ _min = 40 °.

The distance t between the mask 9 and the cooling can roll 7
Was changed to 1, 3, 5 mm, and when t was 1, 3 mm, an evaporation material was deposited between the mask 9 and the cooling can roll 7 during the deposition, and the deposition was performed. Since the material came into contact with the cooling can roll 7, the film formation was stopped at that time. Therefore, the vapor deposition efficiency when the distance t is 5 mm,
Hc is shown in Table 2. Hc is such that the crucible distance from one of the two cooling can rolls is equal to that of the embodiment, (X, Y).
= (500, 200), (500, 300) and (50)
0, 400), the values at 100 m and 900 m of film feed from the start of film formation were measured in the same manner as in the example. Further, the vapor deposition efficiency was calculated in the same manner as in the example.

[0023]

[Table 2]

As is clear from the results of Tables 1 and 2,
When the apparatus of the present invention and the conventional apparatus are compared for the case where the crucible position Y is the same, the vapor deposition efficiency of the conventional apparatus is higher than the vapor deposition efficiency at the position X, regardless of the position of X in the apparatus of the present invention. It is always a large value. That is, for example, when Y = 200, X = 3 in the conventional device.
At the time of 00, the vapor deposition efficiency is 12.2% at the maximum, but in the apparatus of the present invention, it is 17.2% at the minimum and 20.3% at the maximum.

Moreover, in the apparatus of the present invention, a running base film is used as a mask for regulating the maximum incident angle. Since a change in the angle can be prevented, stable magnetic characteristics can be maintained for a long time.

In Table 1, when the evaluation results of the distance L between the two cooling can rolls 21 and 22 are compared, for each Y value, when the distance L is 3 mm or less, the guide roll of the traveling room And no adhesion to the inner wall,
Since the vapor that has entered the traveling chamber does not adhere to the non-magnetic substrate before the vapor flow at the maximum incident angle adheres to the non-magnetic substrate, good magnetic properties can be obtained. Therefore,
When the magnetic characteristics required for the magnetic recording medium are not so strict, the distance L between the cooling can rolls is 3 m.
Although there is no practical problem even if it exceeds m, it has been confirmed that it is desirable to set it to 3 mm or less when the required characteristics are strict.

From the above, the advantages of the manufacturing apparatus of the present invention can be summarized as follows: (1) The vapor deposition efficiency can be greatly improved, and the manufacturing cost can be greatly reduced. (2) Since the amount of material adhering to the inner wall and the anti-adhesion plate in the vacuum device is reduced, dust in the device caused by peeling of the adhered film is reduced, and tape dropout due to the dust is reduced. it can. Further, the number of times of cleaning in the apparatus is reduced, and the productivity is improved. (3) There is no change in the maximum incident angle due to a change in the mask dimension, and a magnetic recording medium having predetermined characteristics can be reliably produced for a long time. Further, by setting the interval L between the two cooling can rolls to 3 mm or less, it is possible to sufficiently cope with strict required characteristics.

[0028]

As described in detail above, according to the present invention, two cooling can rolls are juxtaposed at an extremely small interval, and the evaporation is simultaneously performed from one crucible under the same conditions. High efficiency of material deposition, reduced dust in vacuum equipment, reduced number of cleanings in equipment, and no change in mask dimensions, so productivity of magnetic recording media with excellent magnetic properties Can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of a configuration of a film forming apparatus which is a main part of a magnetic recording medium manufacturing apparatus of the present invention.

FIG. 2 is a conceptual diagram showing a configuration of a conventional film forming apparatus.

[Explanation of symbols]

 1 'Vacuum tank 8 Crucible 12 Electron gun 13 Electron beam 21, 22 Cooling can roll 23, 24 Non-magnetic substrate (base film) 25 Magnetic material evaporation source 31, 33 Unwind roll 32, 34 Take-up roll 41, 42, 43 , 44 Guide roll 51, 52 Mask

Claims (2)

[Claims] An apparatus for manufacturing a magnetic recording medium, wherein a magnetic film is formed by depositing a vapor flow from an evaporation source of a magnetic material on a non-magnetic substrate by an oblique deposition method, comprising: The cooling source is provided with two cooling can rolls for running the substrate, and these cooling can rolls are juxtaposed so that their rotation axes are parallel to each other and with a small gap. And a maximum incident angle of a vapor flow from the evaporation source to a first non-magnetic substrate is regulated by the second non-magnetic substrate. An apparatus for manufacturing a magnetic recording medium, wherein a maximum incident angle of a vapor flow from the substrate to the second non-magnetic substrate is regulated by the first non-magnetic substrate. 2. The manufacturing apparatus according to claim 1, wherein the minute gap between the two cooling can rolls is 3 mm or less.