JPH10112024A - Production of magnetic recording medium and producing device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent elongation or deformation of a recording medium due to electrostatic force when a nonmagnetic supporting body is parted from a cooling drum. SOLUTION: A magnetic recording medium is produced by bringing a nonmagnetic supporting body 5 into contact with a cooling drum 3 which rotates at a const. speed and forming a thin magnetic metal film on the nonmagnetic supporting body 5 in vacuum except for the side edge parts of the body 5. In this method, after the thin metal magnetic film is formed on the nonmagnetic supporting body 5 and before the nonmagnetic supporting body 5 is parted from the cooling drum 3, the center surface of the nonmagnetic supporting body 5 where the thin magnetic metal film is formed is covered with a protective plate 15 and a thin antistatic metal film is formed in vacuum on both of the side edge parts where the thin magnetic metal film is not formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a magnetic recording medium and an apparatus for manufacturing the same. More specifically, the present invention relates to a method and an apparatus for manufacturing a magnetic recording medium for forming a magnetic metal thin film by forming a film on a tape-shaped magnetic recording medium in a vacuum.

[0002]

2. Description of the Related Art A tape-shaped magnetic recording medium is used as an information recording medium for recording and reproducing audio, video and other various data. As a conventional magnetic recording medium, a magnetic powder material such as a magnetic oxide powder or a magnetic alloy powder is coated on a tape-shaped non-magnetic support by a vinyl chloride-vinyl acetate copolymer, a polyester resin, a urethane resin, or a polyurethane. A coating type magnetic recording medium prepared by applying and drying a magnetic paint dispersed in an organic binder such as a resin has been widely used.

On the other hand, with the recent increase in demand for high-density magnetic recording, a magnetic metal material such as a Co—Ni alloy, a Co—Cr alloy, or Co—O is formed by plating or vacuum deposition. A so-called magnetic metal thin film type magnetic recording medium, which is directly deposited on a non-magnetic support such as a polyester film, a polyamide, or a polyimide film by a forming means (a vacuum deposition method, a sputtering method, an ion plating method, or the like), has been proposed. Has been put to practical use.

The magnetic metal thin film type magnetic recording medium is excellent in coercive force, squareness ratio, etc., and is excellent in electromagnetic conversion characteristics at short wavelengths. And the thickness loss at the time of reproduction is remarkably small, and there is no need to mix the binder which is a non-magnetic material in the magnetic metal film, so that the packing density of the magnetic material can be increased. I have.

In recent years, when a magnetic metal film of a magnetic recording medium is formed in order to improve the magnetic conversion characteristics of the magnetic recording medium and obtain a larger output, the magnetic metal film is obliquely deposited. The so-called oblique deposition is proposed and put to practical use.

In the film formation by vapor deposition, not limited to the above-described oblique vapor deposition, since a high-temperature metal vapor is directly adhered to a non-magnetic support, a cooling drum (both cooling cans) is used so that the non-magnetic support is not melted by the high-temperature vapor. ), And the magnetic metal film is formed while being cooled by being wound.

In this vapor deposition, a magnetic metal film is formed only on a central portion of the non-magnetic support except for both side edges to prevent the vapor deposition metal from adhering to the peripheral surface of the cooling drum. . By the way, when the magnetic metal film is entirely deposited on the non-magnetic support, the scattered deposited metal adheres to the exposed peripheral surface of the rotating cooling drum, and it is very difficult to remove the adhered magnetic metal film. Because it becomes troublesome.

[0008]

Since the nonmagnetic support is made of a synthetic resin film, static electricity is easily charged. In particular, both side edges of the non-magnetic support on which the magnetic metal film is not formed are made of the non-magnetic support itself and have no conductivity, and thus are easily charged with static electricity and easily adhere to the cooling drum. Therefore, when the nonmagnetic support separates from the cooling drum, the nonmagnetic support is hardly peeled off and stretches or deforms. for that reason,
Both side edges of the roll of the manufactured magnetic recording medium are swelled, and the shape defect of this portion makes the roll unusable as a magnetic recording medium (magnetic tape). This phenomenon becomes more conspicuous as the thickness of the non-magnetic support becomes thinner, and has become a major obstacle to the tendency of thinning for high-density recording.

SUMMARY OF THE INVENTION The present invention has been made in view of the above prior art, and provides a method and apparatus for manufacturing a magnetic recording medium for preventing elongation and deformation when a non-magnetic support is separated from a cooling drum. With the goal.

[0010]

In order to achieve the above object, according to the present invention, a tape-shaped non-magnetic support is brought into contact with a cooling drum rotating at a constant speed in a vacuum, and both side edges are removed. In the method of manufacturing a magnetic recording medium for forming a magnetic metal thin film on the non-magnetic support, the method comprises: forming a magnetic metal thin film on the non-magnetic support; A method for manufacturing a magnetic recording medium, comprising forming an antistatic metal thin film on both side edges of a support.

According to this structure, after the magnetic metal thin film is formed on the non-magnetic support, before the non-magnetic support separates from the cooling drum, both side edge portions of the non-magnetic support where the magnetic metal thin film is not formed are formed. Since the metal thin film is formed on top of the non-magnetic support in which no metal thin film is formed, both side edges of the non-magnetic support become conductive and the static electricity is removed, and the non-magnetic support is removed from the cooling drum. The separation is easily performed when the magnetic recording medium is separated, and the elongation and deformation of the manufactured magnetic recording medium are prevented. The charge removing the metal thin film is, for example, an aluminum thin film, the electrical resistance value in the thickness 5~50nm is 10 ² Omega
It is about.

By providing such a metal thin film for static elimination, a defective shape of the magnetic recording medium (magnetic tape) is eliminated, the thinning of the magnetic tape is promoted, and high-density recording becomes possible.

Further, since the metal thin film is formed thinly on both side edges of the non-magnetic support, even if the deposited metal scatters and adheres to the peripheral surface of the cooling drum when forming the thin film, only a small amount is formed. Yes, and can be easily removed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a preferred embodiment,
The antistatic metal thin film is formed by sputtering.

According to this method, a metal thin film can be efficiently formed at a desired position in a vacuum with high accuracy by a controllable sputtering method.

In a further preferred embodiment, aluminum is used as the sputtering target.

According to this method, a metal thin film can be easily formed at low cost by using aluminum which is generally used as an electrode material in the field of semiconductor production and is easily available and has sufficient conductivity.

In order to carry out the method for manufacturing a magnetic recording medium of the present invention, the present invention provides an apparatus main body capable of evacuating, and a means for transporting a tape-shaped non-magnetic support provided in the apparatus main body. A cooling drum for cooling the non-magnetic support conveyed in the apparatus main body; and a magnetic metal thin film formed on a predetermined position of the non-magnetic support except for both side portions in a state where the non-magnetic support is in contact with the cooling drum. A magnetic film forming means for forming the magnetic recording medium, wherein the anti-magnetic metal thin film is formed on both sides of the non-magnetic support near the position where the non-magnetic support is separated from the cooling drum. A manufacturing apparatus for a magnetic recording medium, characterized in that a thin film forming means is provided.

According to this configuration, since the thin metal thin film is formed on both side edges of the tape-shaped non-magnetic support which is conveyed in a vacuum and where the magnetic metal thin film is not formed, as described above, Both side edges of the non-magnetic support are conductive, and the static charge of those portions is lost, so that the non-magnetic support does not elongate or deform when the non-magnetic support is separated from the cooling drum.

In a preferred embodiment, the magnetic film forming means includes a container filled with a magnetic metal material, an electron gun for heating and evaporating the magnetic metal material in the container, and a predetermined range of the nonmagnetic support. It is characterized by comprising a vacuum vapor deposition device provided with a shutter for masking.

According to this configuration, an electron beam heating type vapor deposition apparatus generally used in the field of semiconductor manufacturing can be adopted, and the present invention can be easily carried out by using an existing apparatus. A magnetic film with few impurities can be formed.

In a further preferred embodiment, the antistatic thin film forming means comprises a sputtering apparatus having a protective plate covering a central portion of the non-magnetic support.

According to this structure, a thin aluminum thin film is satisfactorily adhered in a short time to both sides of the non-magnetic support on which the magnetic metal thin film is not formed by the sputtering, and especially the non-magnetic support is formed. The non-magnetic support is smoothly separated when the non-magnetic support is separated from the cooling drum due to the disappearance of the static electricity on both side edges of the body.

[0024]

1 and 2 show an apparatus for manufacturing a magnetic recording medium according to the present invention. FIG. 1 is an explanatory view of the entire basic configuration, and FIG. 2 is an explanatory view of the configuration as viewed from the direction A in FIG. is there.

The apparatus main body 1 is composed of a closed container. Exhaust ports 2a and 2b are provided on the upper and lower sides of the closed container, and are connected to a vacuum exhaust device (not shown) to form a vacuum closed container. In the center of the apparatus main body 1, for example, a cooling drum 3 internally provided with a cooling device for circulating a refrigerant is arranged, and rotates at a constant speed in a certain direction (clockwise in the figure). A non-magnetic tape-like support 5 is wound around the cooling drum 3 as described later. The non-magnetic support 5 serves as a base material of the magnetic tape.

A partition plate 4 is provided at the center of the apparatus main body 1 in which the cooling drum 3 is disposed, and the apparatus main body 1 formed of a closed container is divided into a first vacuum chamber 4a and a second vacuum chamber 4b. ing.

On one side of the first vacuum chamber 4a, a feed roller 6 around which a tape-shaped non-magnetic support 5 is wound is disposed, and on the other side of the first vacuum chamber 4a, a tape-shaped non-magnetic support is provided. Body 5
The take-up rollers 7 for taking up are arranged at a constant speed in a certain direction (clockwise in the figure). Each roller 6,
7 and the width of the cooling drum 3 are determined by the non-magnetic support 5
The width is almost the same. The non-magnetic support 5 has a width of a plurality of magnetic tapes to be a product, and is cut into a product tape width in a final step.

The non-magnetic support 5 pulled out from the feed roller 6 is transported in the apparatus main body 1, is wound around the cooling drum 3, passes while contacting the surface thereof, and is wound up by the winding roller 7. . At that time, the nonmagnetic support 5 is cooled by the refrigerant while passing through the peripheral surface of the cooling drum 3. This suppresses melting, deformation, and the like of the non-magnetic support 5 due to a rise in temperature when a magnetic metal thin film is formed on the non-magnetic support 5 by vapor deposition described below.

Guide rollers 8a and 8b are arranged between the feed roller 6 and the cooling drum 3 and between the winding roller 7 and the cooling drum 3, respectively. As a result, a predetermined tension is applied to the non-magnetic support 5 running from the feed roller 6 to the cooling drum 3 and from the cooling drum 3 to the take-up roller 7, and the non-magnetic support 5 can run smoothly. .

On one side of the second vacuum chamber 4b, a crucible 10 filled with a metallic magnetic material 9 made of, for example, a Co--Ni alloy, and an electron gun provided at the tip of a cylindrical body projecting obliquely from the side wall 11 and a masking shutter 13 to be described later.
Is provided.

The electron beam emitted from the electron gun 11 is irradiated onto the metal magnetic material 9 in the crucible 10 while scanning in the tape width direction (perpendicular to the drawing), and the metal magnetic material 9 is heated and evaporated. Then, the evaporated metal magnetic material 9 is formed as a magnetic metal thin film on the non-magnetic support 5 running on the peripheral surface of the cooling drum 3. By such a heating method using electron beam irradiation, high melting point substances can be easily evaporated,
Also, the temperature of the container (crucible) does not become high, and the risk of impurities being mixed is reduced, so that a high-quality magnetic thin film can be formed.

The space between the cooling drum 3 and the crucible 10 is
A shutter 13 for masking is provided near the cooling drum 3. The shutter 13 is arranged so as to cover a predetermined area of the non-magnetic support 5 running at a constant speed on the peripheral surface of the cooling drum 3, and is arranged so that the deposited metal hits the running non-magnetic support 5 from an oblique direction. Is done. That is, the deposition material adheres only to the central portion except for both side edges of the nonmagnetic support 5,
Further, a shutter 13 is provided so as to adhere to the cooling drum 3 from an oblique direction with respect to the normal line.

An oxygen gas inlet 14 is provided between the cooling drum 3 and the shutter 13 so as to penetrate the side wall of the second vacuum chamber 4b. As a result, oxygen gas is supplied to the deposited metal magnetic thin film, the surface is oxidized, and the magnetic properties, durability and weather resistance are improved.

On the other hand, on the other side of the first vacuum chamber 4a, FIG.
A protective plate 15 for covering a central portion of the non-magnetic support 5 on which the deposited magnetic metal thin film is formed as shown in FIG.
An aluminum cathode (target) 16 for forming a metal thin film of aluminum (Al) on both side edges of the non-magnetic support 5 not covered with the metal, and a sputter discharge gas (A).
A sputter device 18 having an inert gas inlet 17 for introducing r) is provided.

After the vapor deposition, the sputter device 18 forms an aluminum metal thin film on both side edges of the non-magnetic support 5 which is not covered with the protective plate 15, ie, on which no metal magnetic thin film is formed. This metal thin film is formed thin. For this reason, both side edges of the non-magnetic metal thin film on which the non-magnetic metal thin film is formed become conductive, so that static electricity is lost, and the adhesive force when the non-magnetic support 5 separates from the cooling drum 3 is lost. . Note that, in FIG. 2, portions provided to protrude up, down, left, and right of the protection plate 15 are support portions 19 of the protection plate 15.

Next, an embodiment of a method for manufacturing a magnetic recording medium of the present invention using the above-described manufacturing apparatus will be described.

FIG. 3 shows the manufacturing method in order along the steps, and (a) to (c) are plan views of the nonmagnetic support 5 in each step.

First, the nonmagnetic support 5 is stretched between the feed roller 6 and the winding roller 7. That is, the tape-shaped non-magnetic support 5 is fed from the feed roller 6 wound in a roller shape.
And is wound around the cooling drum 3 rotating at a constant speed via the guide rollers 8a and 8b so as to be brought into contact with the cooling drum 3 and wound up by the winding roller 7. This tape-shaped non-magnetic support 5
Is made of a film-shaped resin plate having a predetermined thickness and width W (for example, 500 mm) and a resistance of, for example, 10 ¹² ohms.

In this state, the electron gun 11 is applied to the magnetic metal material 9 filled in the crucible 10 by using the vacuum evaporation apparatus 12.
An electron beam is emitted from the substrate and irradiated by heating while reciprocating scanning in the width direction of the tape. The evaporated magnetic metal material 9 is transferred to the non-magnetic support 5 running at a constant speed together with the cooling drum 3.
Splatters towards. This evaporated metal is supplied to the shutter 13 described above.
As shown in FIG. 3B, the magnetic metal thin film 20 is formed on both side edge portions 5 a of the nonmagnetic support 5.
It is formed at the central portion except for (for example, each width S = 20 mm).

The materials of the nonmagnetic support 5 used in this example and the conditions for vapor deposition are shown below.

Base: polyethylene terephthalate 10 μm, 500 mm width Undercoat: water-soluble latex containing acrylic ester as a main component Density: 10 million / mm ² Vapor deposition conditions Ingot: Co90-Ni 10 wt% Incident angle: 50 degrees Tape speed: 55 m / min Magnetic Layer thickness: 0.2 μm Oxygen introduction amount: 2.0 × 10 ⁻⁵ m ³ / sec Vacuum degree during vapor deposition: 7 × 10 ⁻² Pa In this vacuum vapor deposition, between the crucible 10 and the cooling drum 3 as described above. The vapor deposition direction is controlled by a shutter 13 provided in the cooling drum 3, the normal direction perpendicular to the tangent to the cooling drum 3 is masked, and the vapor deposition metal is slanted with respect to the nonmagnetic support 5 above (that is, Irradiation (not oblique but not perpendicular). As a result, the magnetic metal thin film 20 having the magnetic layer deposited in the oblique direction is formed at the central portion of the nonmagnetic support 5 excluding the side edge portions 5a.

The reason why the magnetic metal thin film 20 is formed only in the central portion of the non-magnetic support 5 is as described above.
When the magnetic metal thin film 20 is deposited up to both side edge portions 5a of
This is because the vapor deposition metal scattered during the vapor deposition adheres to the exposed peripheral surface of the cooling drum 3, and it is troublesome to remove the vapor deposition metal later.

Next, the non-magnetic support 5 running on the peripheral surface of the cooling drum 3 on which the magnetic metal thin film 20 is deposited is immediately before leaving the cooling drum 3 by a sputtering device 18 using aluminum as a target. 3 are provided on both side edge portions 5a of the non-magnetic support 5 on which the thin film 20 is not formed.
As shown in (c), a metal thin film 21 made of aluminum (Al) is formed.

The metal thin film 21 is formed by connecting the central portion of the nonmagnetic support 5 on which the magnetic metal thin film 20 is formed with the protective plate 1.
5 and the inert gas (A)
In the state where r) is supplied, the process is performed under the minimum thickness forming condition necessary for static elimination. Therefore, the metal thin film 21 is thin on only the side edge portions 5a of the nonmagnetic support 5 where the magnetic metal thin film 20 is not formed, for example, 5 nm to 50 nm (0.005 nm).
μm-0.05 μm).

At this time, the Al metal scatters around by sputtering, but the amount is small and does not adhere to the peripheral surface of the cooling drum 3. Even if it adheres, it is very slight and can be easily removed.

The conditions for this sputtering are shown below.

Method: DC magnetron sputtering Target material: Aluminum Input power: 5 W / cm Gas used: Argon Vacuum degree: 2 Pa By forming such a metal thin film 21, conduction on both side edge portions 5 a of the nonmagnetic support 5 is achieved. (Magnetic metal thin film 2 with resistance
The resistance is as low as 10 ² ohms, which is almost the same as the zero portion), the electrostatic charge is lost, and the adhesion to the cooling drum 3 is lost. For this reason, when the non-magnetic support body 5 separates from the cooling drum 3 thereafter, it separates without applying an adhesive force due to electrostatic attraction. Therefore, the side edges 5a of the non-magnetic support 5 do not elongate or deform.

When the conventional sputtering is not performed, the maximum height of the non-magnetic support 5 is 8 mm to 10 mm, and the range where the height of 2 mm or more exists is from the side edges of the non-magnetic support 5. The distance was up to 50 mm and the yield was 87%.

On the other hand, in the case of the embodiment of the present invention, the maximum height of the non-magnetic support 5 is 1 mm at the magnetic film forming portion.
In the range where the swell of 2 mm or more exists, the distance from both side edges of the nonmagnetic support 5 is 5 mm, and there is no swell of 2 mm or more in the center magnetic film forming portion. The yield was 100%.

After that, the non-magnetic support 5 on which the metal magnetic thin film 20 and the thin metal thin film 21 are formed is taken up by the take-up roller 7. Thus, a magnetic recording medium (magnetic tape) is manufactured.

In the above embodiment, the magnetic metal thin film 20 made of Co--Ni is deposited on the non-magnetic support 5 by vapor deposition. You can use what is used. For example, ferromagnetic metals such as Fe, Co, and Ni, Fe—Co,
Co-Ni, Fe-Co-Ni, Fe-Cu, Co-C
u, Co-Au, Co-Pt, Fe-Cr, Co-C
r, Ni-Cr, Fe-Co-Cr, Co-Ni-C
r, a ferromagnetic alloy such as Fe-Co-Ni-Cr.

These may be single-layer films or multilayer films. Further, a base layer or an intermediate layer may be provided between the nonmagnetic support 5 and the magnetic metal thin film 20 or, in the case of a multilayer film, for improving the adhesion between the layers and controlling the coercive force. Further, the magnetic metal thin film 20 may be oxidized to an oxide in order to improve the corrosion resistance of the surface of the magnetic layer.

As a means for forming the magnetic metal thin film 20, a vacuum evaporation method of heating and evaporating a ferromagnetic material under vacuum to deposit the ferromagnetic material on a non-magnetic support, or an ion-forming method for evaporating the ferromagnetic metal material during a discharge. Plating method, sputtering method that strikes out atoms on the surface of the target with argon ions generated by glow discharge in an atmosphere containing argon as a main component,
Suitable means by so-called PVD technology can be used.

Further, the structure of the non-magnetic support (magnetic tape) may be such that a back coat layer is formed as necessary, an undercoat layer is formed on the non-magnetic support, a lubricant, a rust inhibitor, etc. There is no problem in forming the layer. In this case, any known materials can be used as the nonmagnetic pigment, resin binder or lubricant contained in the back coat layer, and the material contained in the rust preventive layer.

Further, as the antistatic metal thin film 21 formed by sputtering, the aluminum (A) used in the above embodiment was used.
In addition to l), non-magnetic and magnetic metals such as Cu, Cr, Ni, Co, and Fe can be used.

[0056]

As described above, according to the present invention, after the magnetic metal thin film is formed on the non-magnetic support, before the non-magnetic support separates from the cooling drum, the magnetic metal thin film of the non-magnetic support is removed. Since a metal thin film is formed in vacuum on both side edges where no metal thin film is formed, both side edges of the non-magnetic support on which no metal thin film is formed become conductive, and static electricity is removed and cooling is performed. The separation when the non-magnetic support is separated from the drum is easily performed, and the elongation and deformation of the manufactured magnetic recording medium are prevented.

Accordingly, the magnetic recording medium (magnetic tape) is free from shape defects, the production yield is largely improved, and the magnetic tape can be made thinner, thereby realizing a magnetic tape capable of high-density recording. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a basic configuration of an embodiment of a magnetic recording medium manufacturing apparatus according to the present invention.

FIG. 2 is an explanatory view of a configuration viewed from a direction A in FIG. 1;

FIG. 3 is a plan view of a non-magnetic support, showing one embodiment of a method of manufacturing a magnetic recording medium according to the present invention in order along a process.

[Explanation of symbols]

1: apparatus main body, 3: cooling drum, 5: non-magnetic support, 5
a: side edge portion, 6: feed roller, 7: winding roller,
9: magnetic metal material, 10: crucible, 11: electron gun, 1
2: evaporation apparatus, 15: protective plate, 16: aluminum cathode (target) for sputtering, 17: inert gas inlet,
18: sputtering apparatus, 20: magnetic metal thin film, 21: antistatic metal thin film.

Claims (6)

[Claims] 1. A magnetic recording medium in which a magnetic metal thin film is formed on a non-magnetic support except for both side edges while a tape-shaped non-magnetic support is in contact with a cooling drum rotating at a constant speed in a vacuum. In the manufacturing method, after forming the magnetic metal thin film on the non-magnetic support, before the non-magnetic support separates from the cooling drum, an antistatic metal thin film is formed on both side edges of the non-magnetic support. A method for manufacturing a magnetic recording medium, comprising: 2. The method according to claim 1, wherein the antistatic metal thin film is formed by sputtering. 3. The method according to claim 2, wherein aluminum is used as the sputtering target. 4. An apparatus main body capable of evacuating, a means for transporting a tape-shaped non-magnetic support provided in the apparatus main body, a cooling drum for cooling the non-magnetic support conveyed in the apparatus main body, A magnetic film forming means for forming a magnetic metal thin film at a predetermined position on the non-magnetic support except for both side edges while the non-magnetic support is in contact with the cooling drum; Manufacturing a magnetic recording medium, wherein thin film forming means for forming an antistatic metal thin film on both side edges of the non-magnetic support is provided near a position where the non-magnetic support is separated from the cooling drum; apparatus. 5. The magnetic film forming means includes a container filled with a magnetic metal material, an electron gun for heating and evaporating the magnetic metal material in the container, and a shutter for masking a predetermined area of the non-magnetic support. The apparatus for manufacturing a magnetic recording medium according to claim 4, comprising a vacuum evaporation apparatus provided with the magnetic recording medium. 6. A magnetic recording medium manufacturing apparatus according to claim 4, wherein said antistatic thin film forming means comprises a sputtering apparatus having a protective plate covering a central portion of said nonmagnetic support. .