JPH0714155A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic tape in which the generation frequency of dropout is extremely small. CONSTITUTION:A polishing tape 5 and a nonmagnetic supporting body 1 on which a metal magnetic thin film is formed by oblique vapor deposition method are arranged in such manner that the metal magnetic thin film side and the abrasive side face each other. A roll 3 having <=50mm diameter is attached by pressing from the back surface of the polishing tape 5 to bring the tape into contact with the magnetic thin film. In this state, the metal magnetic thin film is travelled in the direction opposite to the growing direction of the columnar structure of the thin film so that the surface of the metal magnetic thin film is polished. Thereby, no scratche is produced on the surface of the metal magnetic thin film due to abrased material from the film, or deposition of abrased particles on the thin film surface is prevented. Thus, projections on the surface of the metal magnetic thin film can be efficiently removed by grinding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium, and more particularly to a surface treatment method for a metal magnetic thin film.

[0002]

2. Description of the Related Art Conventionally, as a magnetic recording medium, a powder magnetic material such as an oxide magnetic powder or an alloy magnetic powder on a non-magnetic support is used as a vinyl chloride-vinyl acetate copolymer, polyester resin, urethane resin, A so-called coating type magnetic recording medium in which a magnetic layer is formed by coating and drying a magnetic coating material dispersed in an organic binder such as polyurethane resin is widely used.

Further, with the increasing demand for high-density recording, metal magnetic materials such as Co--Ni alloy, Co--Cr alloy, and Co--O are plated or vacuum thin film forming means (vacuum evaporation method, sputtering method, ion). There is proposed a so-called metal magnetic thin film type magnetic recording medium in which a magnetic layer is formed by directly depositing it on a non-magnetic support using a plating method or the like).

This metal magnetic thin film type magnetic recording medium is excellent in coercive force, squareness ratio and the like, and since the thickness of the magnetic layer can be made extremely thin, recording demagnetization and thickness loss at the time of reproduction are extremely small and at a short wavelength. Excellent electromagnetic conversion characteristics. Not only that, but there is no need to mix a binder that is a non-magnetic material in the magnetic layer, so that the packing density of the magnetic material can be increased, and there are various advantages. As described above, the metal thin film type magnetic recording medium is considered to be the mainstream of the medium for high density recording because it is superior in magnetic characteristics to the coating type magnetic recording medium. An oblique vapor deposition type magnetic recording medium having a metal magnetic thin film formed by vapor deposition as a magnetic layer has very good electromagnetic conversion characteristics, reproduction output and the like, and has already been put to practical use.

In the magnetic recording medium, in order to improve the high density recording characteristics, it is necessary to smooth the surface of the magnetic layer to reduce the spacing loss. Even in the medium, the magnetic layer is becoming more and more smooth in surface.

However, when the surface of the magnetic layer becomes smooth, the contact area with the head becomes large, so that the frictional force with the head increases during recording and reproduction, and a large shear stress is generated in the magnetic layer. When such a large shearing stress occurs in the magnetic layer, the surface protrusions that remain on the surface of the magnetic layer that cannot be completely smoothed are sheared and destroyed, and fine magnetic powder (hereinafter,
It is called abrasion powder. ), The magnetic recording medium and the head are interposed. The abrasion powder present between the magnetic recording medium and the head causes a dropout, which causes deterioration of image quality in a VTR, for example.
It induces sound skipping and, in the worst case, causes head clogs, which makes even recording and reproduction impossible. Further, in recent years, in the field of magnetic recording, analog magnetic recording is being shifted to digital magnetic recording, but it is considered that the influence of such abrasion powder becomes a big problem in digital magnetic recording.

Therefore, in order to prevent the generation of such abrasion powder, a metal magnetic thin film is formed by the oblique evaporation method, and then the columnar structure of the metal magnetic thin film is grown on the surface of the formed metal magnetic thin film. A surface treatment method for removing surface protrusions by sliding an abrasive tape along the direction is disclosed in JP-A-63-16.
7425 publication. The sliding direction of the polishing tape is set to the direction along the growth direction of the metal magnetic thin film when the polishing tape is slid in the direction opposite to the growth direction of the metal magnetic thin film. This is because scratches are formed on the surface.

[0008]

However, in the above method, between the sliding metal magnetic thin film and the polishing tape, the ground object once ground from the metal magnetic thin film is formed on the surface of the metal magnetic thin film and the surface of the polishing tape. There is a problem that it is caught and scratches are formed on the surface of the metal magnetic thin film, or it reattaches to the surface of the metal magnetic thin film, and the disadvantage that the reattached ground object and scratches also induce dropout .

Therefore, the present invention has been proposed in view of such a conventional situation, and when grinding and removing the surface protrusions from the formed metal magnetic thin film, the present invention uses a grinding object ground from the metal magnetic thin film. To provide a method for manufacturing a magnetic recording medium capable of efficiently grinding and removing protrusions on the surface of a metal magnetic thin film without forming scratches on the surface of the metal magnetic thin film or reattaching a ground object to the surface of the metal magnetic thin film. To aim.

[0010]

In order to achieve the above-mentioned object, the inventors of the present invention have conducted extensive studies, and as a result, when grinding and removing the surface protrusions from the metal magnetic thin film, the metal magnetic thin film and the polishing tape are slid. We have come to the knowledge that when the dynamic length is shortened, the surface protrusions of the metal magnetic thin film can be efficiently ground and removed without causing reattachment of a ground object on the surface of the metal magnetic thin film and formation of scratches.

The method for producing a magnetic recording medium of the present invention has been completed based on such findings, and after forming a metal magnetic thin film on a non-magnetic support by oblique vapor deposition,
The non-magnetic support and the polishing tape are connected to each other on the metal magnetic thin film side,
Arranged so that the abrasive side faces each other, and a roll having a diameter of 50 mm or less is pressed against the back side of the polishing tape to bring them into contact with each other, and in this state, the metal magnetic thin film runs in the direction opposite to the growth direction of the columnar structure. Thus, the surface of the metal magnetic thin film is polished.

Further, when the metal magnetic thin film is slid in a direction opposite to the growth direction of the columnar structure, the polishing tape is run in the same direction as the running direction of the metal magnetic thin film.

[0013]

The nonmagnetic support on which the metal magnetic thin film is formed by the oblique vapor deposition method and the polishing tape are arranged so that the metal magnetic thin film side and the abrasive side face each other, and the back side of the polishing tape. When a small-diameter roll having a diameter of 50 mm or less is pressed and protruded, the polishing tape and the metal magnetic thin film uniformly contact in the width direction within a relatively short contact length range. When the metal magnetic thin film is run in the direction opposite to the growth direction of the columnar structure in this state, the polishing tape slides on the surface of the metal magnetic thin film in the normal direction to the columnar direction of the metal magnetic thin film, and the protrusion is ground. To be done. At this time, since the sliding length of the metal magnetic thin film and the polishing tape is short, the ground object that has been ground is quickly separated from the surface of the metal magnetic thin film without traveling in the metal magnetic thin film for a long time. Therefore, the reattachment of the grinding material to the surface of the metal magnetic thin film and the formation of scratches caused by the staying of the grinding object between the metal magnetic thin film and the polishing tape are suppressed, and the magnetic field with a very low dropout frequency is suppressed. The tape will be won.

At this time, if the polishing tape is made to run in the same direction as the running direction of the non-magnetic support at a speed lower than the running speed of the non-magnetic support, it is more likely to be run between the metal magnetic thin film and the polishing tape. The grind material is efficiently separated, and the re-adhesion of the grind material and the formation of scratches on the surface of the metal magnetic thin film are more reliably prevented.

[0015]

EXAMPLES Specific examples of the present invention will be described below with reference to the drawings, but it goes without saying that the present invention is not limited to these examples.

To manufacture a magnetic recording medium, first, a metal magnetic thin film is formed on a non-magnetic support by the oblique evaporation method.

The vapor deposition apparatus used in this example is shown in FIG. That is, in the above vapor deposition apparatus, the inside of the chamber 21 whose inside is made into a high vacuum state by the exhaust pipe 35, the traveling system including the unwinding roll 23, the winding roll 24, and the cooling can 25, and the metallic magnetic material as the evaporation source. It is configured by accommodating an accommodating container 28 accommodating 29 and an oxygen gas introducing pipe 34 for introducing oxygen gas during vapor deposition.

The unwinding roll 23 and the cooling can 2
5, the winding roll 24 has a long non-magnetic support 2
2 are sequentially wound around and sent out from the unwinding roll 23 on the cooling can 25 side and finally wound up by the winding roll 24. A cooling device (not shown) is provided inside the cooling can 25 so as to control deformation of the non-magnetic support 22 due to temperature rise.

The storage container 28 has the cooling can 25.
Is disposed below. The metallic magnetic material 29 accommodated in the accommodating container 28 is heated and evaporated by the electron gun 30, and is deposited and formed as a magnetic layer on the non-magnetic support 22 running around the cooling can 25. It is done like this.

In the vicinity of the outer periphery of the cooling can 25, a curved shutter 33 for blocking a metal vapor flow due to heating and evaporation of the metal magnetic material 29 is provided. The shutter 33 covers a predetermined range of the non-magnetic support 22 so that the metal vapor flow is obliquely deposited on the non-magnetic support 22 within a predetermined angle range.
Further, in the vicinity of the cooling can 25, the mask 3 is formed in an arc shape in the downstream side from the portion where the shutter 33 is provided.
2 is provided, and a partition plate 31 for vertically partitioning the portion of the chamber 21 excluding the cooling can 25 is provided from the inner wall of the chamber 21 to the vicinity of the outer periphery of the cooling can 25. The mask 32 and the partition plate 31 serve to block the metal vapor flow from hitting unnecessary portions of the magnetic layer and the non-magnetic support 22 which are already formed.

Further, an oxygen gas introducing pipe 34, which is introduced from the outside into the chamber 25, is arranged on the downstream side of the non-magnetic support 22 in the traveling direction, that is, on the low incident angle side of the metal vapor flow. The tip end of the oxygen gas introduction pipe 34 is provided in the vicinity of the cooling can 25, and blows out oxygen gas over the entire width direction of the non-magnetic support 22 that runs along the outer periphery of the cooling can 25. It is done like this.

In order to form a metal magnetic thin film on the non-magnetic support 22 by using the vapor deposition apparatus having the above-described structure, first, the chamber 21 is evacuated and then the take-up roll 23 takes up the take-up roll. The non-magnetic support 22 is run over the 24 side. Then, the metallic magnetic material is heated and evaporated by the electron gun 30, and this metallic vapor flow is supplied to a predetermined angular range of the non-magnetic support 22 that runs along the outer periphery of the cooling can 25 by operating the shutter 33. At this time, oxygen gas is simultaneously supplied to the oxygen gas introducing pipe 3
Introduced by 4. Then, a metal magnetic thin film having an oxide layer on its surface is formed on the non-magnetic support 22 that runs along the outer periphery of the cooling can 25. Then, the non-magnetic support 22 on which the metal magnetic thin film is formed is wound around the winding roll 24. The oxide layer is formed on the metal magnetic thin film for the purpose of improving magnetic characteristics such as coercive force, durability, and electromagnetic conversion characteristics.

As the metal material which is obliquely vapor-deposited by the vapor deposition apparatus, any of those usually used in the main medium can be used. For example, in addition to Co—Ni alloys, Co—Pt alloys, Co—Ni—Pt alloys, Fe—C
o alloy, Fe-Ni alloy, Fe-Co-Ni alloy, Fe
-Co-B alloy, Co-Ni-Fe-B alloy, etc. can be used.

As the non-magnetic support, those usually used in this type of medium can also be used. For example, polyethylene terephthalate (PET) film, polyester film such as polyethylene-2,6-naphthalate, or aromatic polyamide. Examples include films and polyimide resin films.

Here, the metal magnetic thin film formed by the oblique vapor deposition method has minute projections on the surface due to the limitation of film formation accuracy. If the projections are left as they are, the projections are scraped off during recording and reproduction, and the polishing powder is removed. Will cause dropout. Therefore, the protrusions that cause such dropout are ground and removed by sliding the polishing tape on the surface of the metal magnetic thin film. To slide the polishing tape on the metal magnetic thin film, the non-magnetic support and the polishing tape are placed at a predetermined distance such that the metal magnetic thin film surface and the polishing material surface face each other, and the back surface of the polishing tape The polishing tape is brought into contact with the metal magnetic thin film by pressing a roll having a diameter of 50 mm or less from the side, and in this state, the nonmagnetic support is run in the direction opposite to the growth direction of the columnar structure of the metal magnetic thin film.

FIG. 2 shows an example of a polishing apparatus which is thus surface-treated. This polishing apparatus comprises a metal magnetic thin film running system 7 for moving and running a metal magnetic thin film and a polishing tape support system 8 for pressing the polishing tape 5 against the metal magnetic thin film.

The metal magnetic thin film running system 7 includes a metal magnetic thin film winding roll 4b and a metal magnetic thin film winding roll 4
a long magnetic non-magnetic support 1 having a metal magnetic thin film formed thereon is successively wound around, is fed from a metal magnetic thin film unwinding roll 4b, and is wound by the winding roll 4a. ing. Further, the metal magnetic thin film winding roll 4b and the metal magnetic thin film winding roll 4 are
Between a, a portion for guiding the portion of the nonmagnetic support 1 slid on the polishing tape 5 wound around the metal magnetic thin film winding roll 4b and the metal magnetic thin film winding roll 4a to a predetermined position. A pair of guide rolls 6 are arranged.

On the other hand, the polishing tape support system 8 includes a polishing tape unwinding roll 2b, a polishing tape winding roll 2a,
A long polishing tape 5 composed of a pressing roll 3 is successively wound over the unwinding roll 2b, the pressing roll 3, and the unwinding roll 2b, and a part of the running polishing tape 5 is pressed by the pressing roll 3. By moving the roll 3 to the metal magnetic thin film side, the roll 3 is pressed against the metal magnetic thin film and is projected to the pressing side together with the metal magnetic thin film. In this polishing apparatus, the metal magnetic thin film and the polishing tape 5 are thus pushed out by the pressing roll 3 so that they are made to come into uniform contact with each other in the width direction under a predetermined tension. As the magnetic thin film runs, the polishing tape 5 slides on the surface of the metal magnetic thin film.

At this time, the sliding length between the metal magnetic thin film and the polishing tape 5 is determined by the diameter of the pressing roll 3 and the wrap angle θ of the metal magnetic thin film with respect to the pressing roll. Here, the diameter of the pressing roll 3 is as small as 50 mm or less. Therefore, for example, even when the metal magnetic thin film and the polishing tape 5 are projected so that the wrap angle θ is about 150 ° in order to generate sufficient tension on the non-magnetic support, Contact length with polishing tape is at most 65.4m
It will be about m.

When the diameter of the pressing roll 3 exceeds 50 mm, if the wrap angle θ is set to about 150 °, the sliding length becomes long and the reattachment of the grinding material to the metal magnetic thin film and the formation of scratches at the contact portion. Occurs. Even if the diameter of the pressing roll exceeds 50 mm, the wrap angle θ is set to 1
If it is set to about 25 °, the sliding length can be suppressed to be short, but this time, the tension generated on the non-magnetic support and the polishing tape is reduced, and the grinding effect is reduced. That is, if the diameter of the pressing roll exceeds 50 mm, the surface properties of the metal magnetic thin film cannot be sufficiently improved in any case.

As the polishing tape, a tape-shaped support coated with an abrasive such as Al ₂ O ₃ , SiO ₂ , SiC, diamond, CrO ₂ or the like is used.

In order to grind and remove the protrusions on the surface of the metal magnetic thin film by the polishing apparatus having such a structure, the metal magnetic thin film is spread over the metal magnetic thin film unwinding roll 4b, the guide roll 6 and the metal magnetic thin film winding roll 4a. The formed non-magnetic support 1 is successively passed over. These rolls 4b, 4a,
It is important to consider the traveling direction of the non-magnetic support 1 when the non-magnetic support 1 is laid over the substrate 6, so that the traveling direction is opposite to the growth direction of the columnar structure of the metal magnetic thin film, that is, the polishing is relatively performed. The tip end side of the columnar structure of the metal magnetic thin film is rolled so that the tape 5 slides in the normal direction with respect to the growth direction of the columnar structure of the metal magnetic thin film.
It is necessary to bridge the non-magnetic support 1 on the b side. At this time, when the non-magnetic support 1 is laid over in such a direction that the polishing tape 25 slides in the direction opposite to the growth direction of the columnar structure of the metal magnetic thin film, the surface of the metal magnetic thin film is polished. It may cause scratches.

On the other hand, the polishing tape take-up roll 2b, the pressing roll 3 and the polishing tape take-up roll 2a are
The polishing tape 5 is sequentially laid over so that the polishing material side is the metal magnetic thin film side, and the pressing roll 3 is moved to the metal magnetic thin film side, whereby the polishing tape 5 is pressed to the metal magnetic thin film and to the pressing side together with the metal magnetic thin film. Overhang.

After setting the non-magnetic support 1 and the polishing tape 5 in the apparatus in this manner, the non-magnetic support 1 is moved and run in the direction opposite to the growth direction of the columnar structure of the metal magnetic thin film. As a result, the polishing tape 5 slides on the metal magnetic thin film in the normal direction with respect to the growth direction of the columnar structure of the metal magnetic thin film, and the protrusions on the surface of the metal magnetic thin film are ground.

At this time, in the above-mentioned polishing apparatus, the pressing roll 3 has a small diameter of 50 mm or less as described above, so that the sliding length between the metal magnetic thin film and the polishing tape 5 is shortened. The ground object that has been ground rapidly separates from the surface of the metal magnetic thin film without running in the sliding portion for a long time as the metal magnetic thin film runs. Therefore, the reattachment of the grinding material to the surface of the metal magnetic thin film and the formation of scratches caused by the staying of the grinding object between the metal magnetic thin film and the polishing tape are suppressed, and the magnetic field with a very low dropout frequency is suppressed. The tape will be won.

At this time, if the polishing tape 5 is made to run in the same direction as the running direction of the non-magnetic support 1 at a speed lower than the running speed of the non-magnetic support 1, the magnetic metal thin film and the polishing tape 5 are made. The grinding material comes out more efficiently from the gap, and the grinding material is reattached to the surface of the metal magnetic thin film,
The formation of scratches is more reliably prevented.

Next, a magnetic tape was actually manufactured using the above polishing apparatus, and the occurrence of dropout was examined.

Example 1 A metal magnetic thin film having a thickness of 2000 nm and containing Co as a main component was formed on a polyethylene terephthalate film having a thickness of 10 μm by using the above oblique vapor deposition apparatus. Then, the non-magnetic support on which the metal magnetic thin film was formed in this manner was set in the above-mentioned polishing apparatus and surface-treated. The surface treatment was carried out under the following surface treatment conditions using a polishing tape obtained by coating SiC having an average particle diameter of 9 μm on a tape-shaped support having a thickness of 25 μm. Surface treatment conditions Abrasive tape feed rate: 0.1 m / min Abrasive tape tension: 2.0 kg Non-magnetic support feed rate: 60 m / min Non-magnetic support tension: 1.5 kg Pressing roll diameter: 15 mm Abrasive tape Lap angle with respect to the pressing roll of: 150 ° Execution sliding length of metal magnetic thin film and polishing tape: 19.6 mm And film thickness of 15 on the surface-treated metal magnetic thin film.
A carbon protective film having a thickness of 10 nm was formed, and perfluoropolyether was top-coated on the protective film to form a lubricant layer, to prepare a magnetic tape.

Example 2 The same procedure as in Example 1 was carried out except that the diameter of the pressing roll, the lapping angle of the polishing tape with respect to the pressing roll, and the actual sliding length of the metal magnetic thin film and the polishing tape were changed as follows. A tape was made. Diameter of pressing roll: 30 mm Lapping angle of polishing tape to pressing roll: 150 ° Actual sliding length of metal magnetic thin film and polishing tape: 39.3 mm

Example 3 The same procedure as in Example 1 was repeated except that the diameter of the pressing roll, the wrap angle of the polishing tape with respect to the pressing roll, and the actual sliding length of the metal magnetic thin film and the polishing tape were changed as follows. A tape was made. Diameter of pressing roll: 50 mm Lapping angle of polishing tape to pressing roll: 150 ° Actual sliding length of metal magnetic thin film and polishing tape: 65.4 mm

COMPARATIVE EXAMPLE 1 Magnetic properties were the same as in Example 1 except that the diameter of the pressing roll, the wrap angle of the polishing tape with respect to the pressing roll, and the actual sliding length of the metal magnetic thin film and the polishing tape were changed as follows. A tape was made. Diameter of pressing roll: 60 mm Lapping angle of polishing tape against pressing roll: 150 ° Actual sliding length of metal magnetic thin film and polishing tape: 78.5 mm

COMPARATIVE EXAMPLE 2 Magnetic properties were the same as in Example 1 except that the diameter of the pressing roll, the wrap angle of the polishing tape with respect to the pressing roll, and the effective sliding length of the metal magnetic thin film and the polishing tape were changed as follows. A tape was made. Diameter of pressing roll: 60 mm Lapping angle of polishing tape against pressing roll: 125 ° Execution sliding length of metal magnetic thin film and polishing tape: 65.4 mm However, in this case, since the wrap angle is small, the non-magnetic support The tension could not be increased to 1.0 kg or more even if the tensile strength of the winding roll was adjusted.

Comparative Example 3 The same procedure as in Example 1 was carried out except that the diameter of the pressing roll, the wrap angle of the polishing tape with respect to the pressing roll, and the actual sliding length of the metal magnetic thin film and the polishing tape were changed as follows. A tape was made. Diameter of pressing roll: 100 mm Lapping angle of polishing tape to pressing roll: 150 ° Execution sliding length of metal magnetic thin film and polishing tape: 131.0 mm

Comparative Example 4 Example 1 except that the metal magnetic thin film was not surface-treated.
A magnetic tape was produced in the same manner as. For each magnetic tape manufactured as described above, the frequency of dropouts was measured using Hi-8VTR (trade name EV-S900). In the dropout measurement, the output is attenuated by 16 dB, and when the output attenuation is continued for 10 μsec and converted into dropout 1, the output is 1
It was performed by setting two levels when the output was attenuated by 0 dB and the output attenuation was continued for 10 μsec as the dropout 1. The results are shown in Table 1. In addition, in Table 1,
The diameter of the pressing roll when the surface treatment was performed, the wrap angle of the polishing tape with respect to the pressing roll, and the actual sliding length of the metal magnetic thin film with respect to the polishing tape are also shown.

[0045]

[Table 1]

As can be seen from Table 1, the magnetic tape using a pressing roll having a diameter of 50 mm or less at the time of surface treatment has a dropout of 100 or less at any level. Therefore, the frequency of dropout is extremely high in the magnetic tape using the pressing roll having a diameter of more than 50 mm in the surface treatment.

The reason why the dropout is high is that, for example, in the magnetic tapes of Comparative Examples 1 and 3, since the sliding length of the metal magnetic thin film and the polishing tape is long during the surface treatment, this metal magnetic thin film is used. This is because the ground material ground at the contact portion between the polishing tape and the polishing tape redeposited on the metal magnetic thin film or formed scratches. In the magnetic tape of Comparative Example 2, since the wrap angle with respect to the pressing roll was small, it was non-magnetic. It is considered that the tension generated on the support became low and the protrusions on the surface of the metal magnetic thin film could not be sufficiently ground.

From the above, when the protrusions on the surface of the metal magnetic thin film are ground and removed by the polishing tape, it is necessary to bring the polishing tape and the metal magnetic thin film into contact with each other by using a pressing roll having a diameter of 50 mm or less. It was found to be effective in efficiently grinding the protrusions on the surface of the metal magnetic thin film by suppressing the reattachment of the ground material to the surface of the magnetic thin film and the formation of scratches, and obtaining a magnetic tape with extremely low dropout frequency. It was

[0049]

As is apparent from the above description, in the method of manufacturing a magnetic recording medium of the present invention, the non-magnetic support on which the metal magnetic thin film is formed by the oblique vapor deposition method and the polishing tape are metal magnetic. The thin film side and the abrasive side are arranged so as to face each other, and a roll having a diameter of 50 mm or less is pressed against the back side of the polishing tape to bring them into contact with each other. In this state, the metal magnetic thin film is formed in a direction opposite to the growth direction of the columnar structure. Since the surface of the metal magnetic thin film is polished by running the metal magnetic thin film, scratches are not formed on the surface of the metal magnetic thin film by the ground object ground from the metal magnetic thin film, and the ground object does not reattach to the surface of the metal magnetic thin film The surface protrusions on the surface of the metal magnetic thin film can be efficiently removed by grinding. Therefore, according to the present invention, it is possible to obtain a magnetic tape in which dropout frequency is extremely low.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a configuration example of an oblique vapor deposition apparatus.

FIG. 2 is a schematic diagram showing a configuration example of a polishing apparatus for applying a surface treatment to a metal magnetic thin film to which the present invention is applied.

[Explanation of symbols]

 1 ... Non-magnetic support 3 ... Pressing roll 5 ... Abrasive tape

Claims (2)

[Claims] 1. A metal magnetic thin film is formed on a non-magnetic support by oblique vapor deposition, and then the non-magnetic support and a polishing tape are arranged such that the metal magnetic thin film side and the abrasive side face each other. The surface of the metal magnetic thin film is polished by pressing a roll having a diameter of 50 mm or less from the back side of the polishing tape to bring them into contact with each other and running the metal magnetic thin film in the direction opposite to the growth direction of the columnar structure in this state. Method for manufacturing magnetic recording medium. 2. The magnetic tape according to claim 1, wherein when the metal magnetic thin film is slid in a direction opposite to the growth direction of the columnar structure, the polishing tape is run in the same direction as the running direction of the metal magnetic thin film. Recording medium manufacturing method.