JP2000030252A - Apparatus for producing magnetic recording medium and crucible used in the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent progress of cracks in a crucible and to prolong the service life of the crucible by forming continuous grooves of a small width, in the sidewall of the crucible enclosing the opening of the crucible along the peripheral edge of the opening. SOLUTION: Two vertical grooves 21, 22 of a small width are formed parallel to each other along the peripheral edge of the opening 20a at a prescribed interval in the sidewall 20b of a crucible 20 enclosing the opening 20a of the crucible 20. The vertical grooves 21, 22 are formed continuously so as to encircle the opening 20a along the peripheral edge of the opening 20a. When vapor deposition is started using the crucible 20, cracks 26 occur and progress is made with the lapse of time, but the further progress of the cracks 26 toward the outer surface of the side wall 20b of the crucible 20 is prevented, because a magnetic material which penetrates from the cracks 26 into the inner vertical grooves 21 when the cracks 26 reach the groove 21 solidifies and is integrated with the sidewall 20b.

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 having a crucible having excellent durability.

[0002]

2. Description of the Related Art In recent years, the recording density of magnetic tapes has been rapidly increased. In this process, the magnetic tape has high coercive force, high magnetic flux density, for example, iron oxide tape,
Metal tapes and thin film tapes are shifting to higher performance ones. As an application of this magnetic tape, in the VTR field, in order to achieve digitization and high definition in the future,
In particular, thin film tapes have attracted attention.

[0003] 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 with an electron beam emitted from a pierce-type electron gun or the like in a vacuum to melt and evaporate these magnetic materials and introduce oxygen. While PET,
By adhering on a base film such as PEN, PI (polyimide), PA (polyamide), CoO,
It is manufactured by forming a thin film made of CoNiO or the like.

FIG. 3 shows a general configuration of a film forming apparatus using an oblique deposition method. In a vacuum chamber 1, an unwinding roll 2, a winding roll 3, guide rolls 4, 5 and a cooling can roll 6 are provided. Are arranged, and a base film 7 is interposed between these rolls.
Is wound and travels from the unwinding roll 2 to the winding roll 3 in the direction indicated by the arrow in the figure. A cooling device (not shown) is provided inside the cooling can roll 6 to prevent the base film 7 from being deformed due to a rise in temperature during vapor deposition.

[0005] A crucible 8 containing a magnetic material 9 is disposed below the cooling can roll 6. A heating means for melting and evaporating the magnetic material 9 is provided on the side wall of the vacuum chamber 1, for example. And a pierce-type electron gun (hereinafter simply referred to as an electron gun) 10. When the base film 7 runs, the maximum incident angle θmax of the magnetic material 9 evaporated from the crucible 8 with respect to the base film 7 is determined by the incident angle regulating mask 11, and the minimum incident angle θmin is similarly determined by the incident angle regulating mask 12 by the predetermined angle mask 12. Deposition is performed at an angle to form a magnetic film. In general, the maximum incident angle θ
max = 90 ° and the minimum incident angle θmin = 40 °.

An electron beam 13 emitted from an electron gun 10
Is controlled in the vicinity of the crucible 8 and the electron beam 1
Deflection magnet 1 for applying a deflection magnetic field to the orbit 3
4 and the deflection magnet 15 inside the electron gun 10. As shown in FIG. 4, the crucible 8 usually has a substantially rectangular bottomed opening 8a, and is installed such that the longitudinal direction of the opening 8a corresponds to the width direction of the base film 7 described above. . An electron beam 13 is applied to a substantially central portion of the magnetic material 9 accommodated in the crucible 8, and the electron material 13 is scanned in the width direction of the base film 8, that is, in the longitudinal direction of the crucible opening 8a. Is dissolved and evaporated.

[0007]

In the above-described apparatus, a predetermined amount of the magnetic material 9 is deposited on the base film 7 and then the take-up roll 3 on which the formed base film 7 is wound is taken out. , The vacuum chamber 1 is released to the atmosphere. At this time, since it takes a long time until the temperature of the magnetic material 9 in the crucible 8 becomes sufficiently low, the production efficiency decreases if the take-up roll 3 is taken out until then.
Therefore, in a state where the temperature of the magnetic material 9 in the crucible 8 is high, the crucible 8 is released to the atmosphere in order to take out the winding roll 3, so that the magnetic material 9 is rapidly cooled. Generally, since the thermal expansion coefficient of the magnetic material 9 is larger than the thermal expansion coefficient of the material forming the crucible 8, the degree of contraction of the magnetic material 9 in the crucible 8 during cooling is smaller than that of the crucible 8 during cooling. As a result, a contraction force acts from the material in the crucible 8 to the crucible 8, particularly to the side wall of the opening, and cracks occur on this side wall.

FIG. 5 is a vertical sectional view taken along the line BB of FIG. 4 for explaining the occurrence of such a crack. As described above, the crack 16 is formed on the side wall 8b of the crucible 8. Thereafter, when the magnetic material 9 is dissolved again and the vapor deposition is started, the dissolved magnetic material 9 permeates into the crack 16. Then, when the take-up roll 3 after film formation is taken out again, the magnetic material 9 which has been cooled and permeated into the cracks 16 is solidified, and the material for forming the crucible 8 and the magnetic material 9 as described above.
The contraction force acts on the crack 16 due to the difference in the coefficient of thermal expansion from the crack 16 and the crack 16 further expands toward the outer surface of the crucible 8.

When the generation of the cracks 16, the penetration of the molten magnetic material 9 into the cracks 16, the solidification of the magnetic material 9, and the expansion of the cracks are repeated, the cracks 16 eventually reach the outer surface of the crucible side wall 8 b. At this point, the crucible 8 becomes unusable. The crucible 8 is expensive, and the magnetic material 9 remaining in the crucible 8 cannot be used, resulting in a large material loss. Therefore, the life of the crucible 8 has a great effect on the material cost of the magnetic tape 7, and thus, if the life of the crucible 8 is short, there is a problem that the manufacturing cost of the magnetic tape 7 increases.

[0010]

In order to increase the production efficiency, the present inventor takes out the winding roll from the vacuum chamber after a relatively short time after the completion of the film formation, whereby cracks are generated in the crucible. It was recognized that this was an unavoidable phenomenon at the present time, and as a result of various studies on means for slowing the progress of the cracks as much as possible, vertical grooves for preventing the progress of the cracks were attached to the side walls of the crucible. It was confirmed that the life of the crucible was greatly increased when formed.

That is, according to the present invention, in the vacuum chamber,
A crucible having a bottomed opening; and a means for evaporating a magnetic material in the crucible to generate a vapor flow, and forming a magnetic film by depositing the vapor flow of the magnetic material on the surface of the non-magnetic substrate. There is provided an apparatus for manufacturing a recording medium, wherein at least one vertical groove having a small width is formed on a side wall surrounding an opening of a crucible and is continuous along the periphery of the opening.

[0012] In the above structure, it is preferable that the vertical groove on the crucible side wall is formed so as to intersect a crack which is generated with time on the crucible side wall during vapor deposition. Further, it is preferable that the above-mentioned deposition of the magnetic material is performed by an oblique deposition method. Further, the above magnetic material is made of Co
It is preferably a magnetic material of the system. In addition, it is preferable that the above-mentioned vapor deposition step forms the magnetic film while introducing oxygen into a vacuum chamber. Further, according to the present invention, the crucible itself having a bottomed opening, and having at least one vertical groove of a minute width formed on a side wall surrounding the opening along the periphery of the opening. Is provided.

[0013]

1 and 2 are views for explaining the structure of a crucible which is a main part of a magnetic recording medium manufacturing apparatus according to the present invention. FIG. 1 is a perspective view, and FIG. 2 is FIG. FIG. 2 is a vertical sectional view taken along line AA of FIG. In the apparatus for manufacturing a magnetic recording medium according to the present invention, components other than the crucible 20 can be the same as those in the conventional manufacturing apparatus described above.

The magnetic material 9 is accommodated in the bottomed opening 20a of the crucible 20. On the side wall 20b surrounding the bottomed opening 20a, vertical grooves having a minute gap substantially parallel to the periphery of the opening 20a, here, two vertical grooves 21 and 22 are formed at predetermined intervals. . And these flutes 2
The reference numerals 1 and 22 are formed continuously along the periphery of the opening 20a so as to make a round around the opening 20a. The number of the vertical grooves is not particularly limited as long as it is one or more. However, it is preferable that the number of the vertical grooves is selected in consideration of the width of the side wall 20b because the effect of preventing the crack from expanding increases. Also, the width of the vertical grooves 21 and 22 is not particularly limited, and is preferably determined in consideration of the number of the vertical grooves, the width of the side wall 20b, and the like. Furthermore, this flute 2
1 and 22 have the purpose of preventing the progress of the crack 26 shown in FIG. 2, and are formed so as to prevent the progress of the crack, ie, specifically, to intersect with the direction of the progress of the crack. Is preferred.

As an apparatus for manufacturing a magnetic recording medium having such a crucible 20, an apparatus using an oblique evaporation method as an evaporation method is particularly preferable. It is preferable to use a Co-based material as the magnetic material 9. Further, it is preferable that the magnetic film is formed while introducing oxygen into the vacuum chamber at the time of vapor deposition.

When vapor deposition is started using the above apparatus,
As shown in FIG. 2, a crack 26 is generated in the crucible 20 with time and progresses. First, when the crucible 20 reaches the inner vertical groove 21, the magnetic material permeated into the vertical groove 21 from the crack 26. 9 is solidified and integrated with the side wall 20b, so that the crack 16 is prevented from further progressing toward the outer peripheral surface of the side wall 20b of the crucible 20. Then, the crack 16 crosses the inner vertical groove 21, and further, the side wall 20b
Progresses toward the outer peripheral surface of the
Reaches the outer vertical groove 22, and the magnetic material 9 which has permeated again solidifies in the vertical groove 22 and is integrated with the side wall 20b, so that the progress of the crack 16 is stopped here. The cracks 16 are generated in all directions from the inner peripheral surface to the outer peripheral surface of the crucible 20. However, as described above, the vertical grooves 21 and 22 are formed so as to make a continuous circuit around the crucible side wall 20b. The longitudinal grooves 21 and 22 can prevent any crack from progressing, and the life of the crucible 20 is greatly improved.

<Example> Three magnesia crucibles 20 each having one to three longitudinal grooves as shown in FIG. 1 were prepared. Specifically, the size of the crucible 20 is 270 mm long ×
620mm wide x 120mm high, opening 150m long
mx 500 mm wide x 60 mm deep, the width of each vertical groove was 5 mm, and the depth was 70 mm.

The crucible 20 is incorporated in the apparatus for manufacturing a magnetic recording medium shown in FIG.
mm cooling can roll, 10,000 m long,
A PET film having a width of 300 mm and a thickness of 6 μm is run on the cooling roll at a speed of 50 m / min, and Co is vapor-deposited while introducing oxygen into the vacuum chamber.
CoO was formed into a film having a thickness of 0.2 μm on the T film.
At this time, the incident angle at the time of film formation of the vapor flow was set at an initial incident angle = 90 ° and a minimum incident angle = 40 °.

Under these conditions, one roll of film is formed, and after completion of the film formation, the film is left in a vacuum state for 2 hours. Thereafter, the vacuum is released to the atmosphere, and the roll on which the film after film formation is wound up. Was taken out. At this time, the state of the crucible 20 was visually observed. Next, a new roll was set in the vacuum chamber, and vacuum evacuation was performed. After reaching a predetermined degree of vacuum, the magnetic material 9 was melted for 1 hour, and vapor deposition was started. The film forming conditions at this time were the same as above. Repeat the film formation in this way,
As described above, each time the film formation of one roll is completed, the crucible 2
0, the life of the crucible 20, ie, the magnetic material 9
The number of film formations until a small amount reached the outer peripheral surface of the crucible 20 was examined. The results are shown in Table 1. For comparison, a film was formed under the same conditions using the same crucible 20 as in the above example except that no vertical groove was formed, and the life was examined. The results are shown in Table 1. .

[0020]

[Table 1]

As is clear from the results shown in Table 1, in the comparative example using the crucible having no vertical groove, the life of the crucible is 5 because the cracks increase each time the film is formed.
Although the number of times, in the embodiment using the crucible 20 in which the vertical grooves 21 and 22 are formed, the life of the crucible 20 is greatly improved, and the life of the crucible 20 increases as the number of the vertical grooves 21 and 22 increases. It was confirmed that it improved.

[0022]

As described in detail above, according to the present invention, the expansion of the cracks generated in the crucible at the time of vapor deposition can be prevented by the longitudinal grooves of the crucible, so that the life of the crucible is greatly improved, It is possible to reduce the manufacturing cost of the tape.

[Brief description of the drawings]

FIG. 1 is a perspective view of a crucible used in a magnetic recording medium manufacturing apparatus according to the present invention.

FIG. 2 is a longitudinal sectional view taken along line AA of the crucible of FIG.

FIG. 3 is a conceptual configuration diagram showing a configuration of a general vapor deposition apparatus.

FIG. 4 is a perspective view of a crucible used in a conventional vapor deposition apparatus.

5 is a longitudinal sectional view of the crucible of FIG. 4 along the line BB.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum tank 2 Unwind roll 3 Take-up roll 4, 5 Guide roll 6 Cooling can roll 7 Base film 9 Magnetic material 10 Pierce type electron gun 13 Electron beam 16, 26 Crack 20 Crucible 20a Crucible opening 20b Opening side wall 21, 22 flute

Claims (3)

[Claims] 1. A crucible having a bottomed opening in a vacuum chamber, and means for evaporating a magnetic material in the crucible to generate a vapor flow, wherein the vapor flow of the magnetic material is applied to a surface of a non-magnetic substrate. In the apparatus for manufacturing a magnetic recording medium for forming a magnetic film by vapor deposition, at least one vertical groove having a small width is formed on a side wall surrounding the opening of the crucible along the periphery of the opening. An apparatus for manufacturing a magnetic recording medium, comprising: 2. The apparatus for manufacturing a magnetic recording medium according to claim 1, wherein the vertical groove on the side wall of the crucible is formed so as to intersect with a crack which occurs with time on the side wall of the crucible during vapor deposition. 3. A crucible having an opening with a bottom and at least one vertical groove having a minute width formed along a peripheral edge of the opening on a side wall surrounding the opening.