JPH05128517A - Manufacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent a nonmagnetic support body from being wrinkled by a method wherein a thermal load to which the nonmagnetic support body is subjected in a vapor deposition operation is relaxed. CONSTITUTION:When a magnetic layer composed of a ferromagnetic metal thin film is formed on a nonmagnetic support body 2 by a vacuum evaporation method, a mask 5 having an opening window 8 in the middle position of a region to be vapor-deposited is arranged and installed with reference to said nonmagnetic support body. At this time, the opening window 8 of said mask 5 is formed to be nearly a trapezoid or a shape equivalent to it, and the boundary between a region in which a magnetic material 7 is applied onto said nonmagnetic support body via the opening window 8 and a region to which the magnetic material 7 is not applied is formed so as to have a prescribed width.

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 in which a ferromagnetic metal thin film serving as a magnetic layer is formed on a non-magnetic support by vapor deposition.

[0002]

2. Description of the Related Art A magnetic material made of a metal or an alloy such as Co-Ni is plated or vacuum thin film forming technology (vacuum deposition method,
A so-called ferromagnetic metal thin film type magnetic recording medium directly deposited on a non-magnetic support such as a polyester film or a polyimide film by a sputtering method, an ion plating method, etc. is excellent in coercive force, squareness ratio, etc. Not only is it excellent in electromagnetic conversion characteristics in the wavelength range, but the thickness of the magnetic layer can be made thin so that thickness loss during recording demagnetization and reproduction is extremely small, or a binder that is a nonmagnetic material in the magnetic layer. Since there is no need to mix in, there are various advantages such as the packing density of the magnetic material can be increased.

In order to improve the electromagnetic conversion characteristics of this kind of magnetic recording medium and obtain a larger output, a magnetic material is obliquely formed as a means for forming a magnetic layer of the magnetic recording medium. The so-called oblique vapor deposition for vapor deposition has been proposed and put to practical use.

[0004]

By the way, in the case of manufacturing a magnetic recording medium by this oblique vapor deposition, a magnetic material is placed in a crucible provided below a cooling can around which a moving non-magnetic support is wound. A magnetic layer is formed by heating and evaporating this magnetic material by a heating means such as an electron beam and depositing the evaporated magnetic material on the non-magnetic support.

At this time, a mask for covering the surface of the cooling can is usually provided in the vicinity of the cooling can in order to prevent the evaporated magnetic material from being deposited on the surface of the cooling can. The vapor flow of the magnetic material is allowed to enter only the surface of the non-magnetic support through the opening window formed in the mask. However, the opening window is usually formed in a rectangular shape. Therefore, since the opening width of the opening window is constant in the traveling direction of the non-magnetic support,
The magnetic layer vapor-deposited through the opening window has a constant width and is formed to have a uniform film thickness in the formation region of the magnetic layer. A region where the magnetic material is not deposited is formed on the non-magnetic support on both sides of the region where the magnetic layer is formed, and a region where the magnetic layer is sandwiched between regions where the magnetic material is not deposited is formed. Boundaries are formed very clearly.

Here, the amount of heat received by the non-magnetic support during vapor deposition is approximately proportional to the film thickness of the magnetic layer formed on the non-magnetic support. Therefore, there is inevitably a large difference in the amount of heat received by the non-magnetic support in each region between the region where the magnetic material is not deposited and the region where the magnetic layer is formed. Therefore, if the thickness of the magnetic layer changes abruptly at the boundary between these regions as described above, a large heat load is generated at this boundary and distortion occurs, causing swelling near this boundary. Or, there is a problem that a shape abnormality such as wrinkles occurs. Such a problem becomes remarkable especially when the non-magnetic support is made of a material having a high heat absorption or an extremely thin film.

Therefore, in the above magnetic recording medium, in order to reduce the heat load on the non-magnetic support during vapor deposition, it is unavoidable to limit the material and thickness of the non-magnetic support.

Therefore, the present invention has been proposed in view of the above-mentioned conventional circumstances, and alleviates the heat load on the non-magnetic support during vapor deposition and prevents wrinkles from forming on the non-magnetic support. An object of the present invention is to provide a method of manufacturing a magnetic recording medium that can be manufactured.

[0009]

A method of manufacturing a magnetic recording medium according to the present invention is proposed to achieve the above-mentioned object. That is, the present invention relates to a method for manufacturing a magnetic recording medium in which a ferromagnetic metal thin film is formed on a non-magnetic support by a vacuum deposition method. It is characterized in that a mask having an opening window is arranged in the middle of the region where vapor deposition is performed, and the opening width of this opening window is varied.

In the present invention, the magnetic thin film forming the magnetic layer of the magnetic recording medium is formed by the vacuum vapor deposition method, and the oblique vapor deposition method is typically employed. The oblique vapor deposition method is a method in which a magnetic material evaporated from an evaporation source is obliquely vapor-deposited on a non-magnetic support that moves and runs along the outer peripheral surface of a cooling can. In such oblique deposition,
In order to prevent the evaporated magnetic material from being deposited on the surface of the cooling can, a mask is provided in the middle of the region where vapor deposition is performed on the non-magnetic support,
The vapor flow of the magnetic material is made to enter only the surface of the non-magnetic support through the opening window formed in the mask.

The opening window is formed so that its opening width varies in the traveling direction of the non-magnetic support. As a result, a magnetic layer near the boundary between the region where the magnetic material is not deposited on the non-magnetic support and the region where the magnetic layer is formed (magnetic layer formation region) is formed with a film thickness distribution. As a result, the heat load at this boundary is alleviated, and wrinkles can be prevented from occurring due to the occurrence of distortion.

The shape of such an opening window is not particularly limited as long as it is formed so that the opening width varies, but is, for example, a trapezoid or an inverted trapezoid, or the non-magnetic support of the opening window. For example, a substantially rectangular shape in which opposite sides in the traveling direction have a zigzag shape can be used. In any case, the larger the amount of change in the opening width, the better the effect. However, it is needless to say that the opening width is at least the width of the magnetic layer to be formed and is narrower than the width of the mask, and thus it is required to be varied within this range.

The magnetic material forming the magnetic thin film may be any of those generally used, but a metal magnetic material is preferably used. In this case, as the metal magnetic material, any of those usually used in this kind of magnetic recording medium can be used. Specifically, magnetic metals such as Fe, Co and Ni, and Fe
-Co, Co-Ni, Fe-Co-Ni, Fe-Co-
Cr, Co-Ni-Cr, Fe-Co-Ni-Cr, etc. are mentioned.

As the non-magnetic support, any of those usually used in this kind of magnetic recording medium can be used. For example, a polyester resin such as polyethylene terephthalate or polyethylene-2,6-naphthalate, or an aroma. Examples thereof include group polyamide films and polyimide resin films.

Further, in the present invention, if necessary,
A step of forming an undercoat film, a step of forming a back coat layer, a top coat layer, or the like on the substrate may be added. In this case, the film forming conditions for the undercoat film, the back coat layer, the top coat layer and the like are not particularly limited as long as they are the methods usually applied to the manufacturing method of this type of magnetic recording medium.

[0016]

When a mask having an opening window is arranged in the intermediate portion of the region where vapor deposition is performed on the non-magnetic support, and evaporation of the magnetic material evaporated through the opening window formed in the mask is performed. A magnetic layer having a film thickness proportional to the time for exposing the non-magnetic support through the opening window is formed.

At this time, if the opening window is rectangular, the opening width is kept constant in the traveling direction of the non-magnetic support. Therefore, as shown in FIG. 3, both ends of the obtained magnetic layer 12 are formed substantially perpendicular to the surface of the non-magnetic support 11, and the boundaries with the region 13 where the magnetic material is not deposited are clear. Formed in. Therefore, the amount of heat received by the non-magnetic support 11 during vapor deposition is determined by the magnetic layer 12
A sharp change occurs at the boundary between the region where the magnetic layer 12 is formed and the region 13 where the magnetic material is not deposited, depending on the film thickness, and a large heat load occurs at this boundary.

On the other hand, if the opening window is formed so that its opening width varies, for example, when the opening window has a trapezoidal shape as shown in FIG.
The exposure time of 1 from the opening window is longer on the inner side than on the outer side of the non-magnetic support 11 depending on the inclination of the hypotenuse of the opening window. Therefore, as shown in FIG. 2, the resulting magnetic layer 12 is formed such that the film thickness at both ends thereof gradually decreases from the inner side to the outer side.

As described above, the magnetic layer 12 in the vicinity of the boundary with the region 13 where the magnetic material is not deposited has a film thickness distribution, and the boundary is formed gently so that the magnetic layer 12 can be deposited during vapor deposition. The heat load caused by the difference in the amount of heat received by the non-magnetic support 11 in the formation region and the region 13 where the magnetic material is not deposited is alleviated.

[0020]

EXAMPLE An example of a method of manufacturing a magnetic recording medium to which the present invention is applied will be specifically described below. First, an example of a manufacturing apparatus used in the method for manufacturing a magnetic recording medium according to the present invention will be described.

In this manufacturing apparatus, as shown in FIG. 1, a tape-shaped non-supporting support 2 is provided along the outer peripheral surface of a cooling can 1 arranged in a vacuum chamber whose inside is in a vacuum state.
1 is moved and run at a predetermined speed in the direction of arrow X in FIG. 1, and the unsupported support 2 is sequentially run from the feed roll 3 arranged in the vacuum chamber to the winding roll 4.

The cooling can 1 is composed of the rolls 3 and 4 described above.
The diameter of the non-supporting member 2 is larger than the diameter of the non-supporting member 2 and is provided in the middle of the traveling from the feed roll 3 to the winding roll 4 side so as to pull out the unsupported support 2 laterally in the drawing. The feed roll 3, the take-up roll 4 and the cooling can 1 each have a cylindrical shape having a length substantially the same as the width of the non-supporting support 2, and the cooling can 1 has an internal structure. A cooling device (not shown) is provided so as to suppress deformation and the like of the non-magnetic support 2 due to temperature rise.

A crucible 6 is provided below the cooling can 1 in the vacuum chamber, and a metal magnetic material 7 is filled in the crucible 6. The crucible 6 has a width substantially the same as the width of the cooling can 1 or a length slightly larger than that of the cooling can 1, and has a concave portion on the upper surface which serves as a housing portion for the metal magnetic material 7. On the other hand, a heating means (not shown) constituted by an electron beam gun or the like is provided on the side of the cooling can 5, and the metallic magnetic material housed in the crucible 6 by this heating means. 7 is heated and evaporated. The evaporated metal magnetic material 7 is deposited and formed as a magnetic layer on the non-magnetic support 2 that runs at a constant speed on the outer peripheral surface of the cooling can 1.

Between the cooling can 1 and the crucible 6 accommodating the metallic magnetic material 7, and in the vicinity of the cooling can 1, a curve is formed so as to face the outer peripheral surface of the cooling can 1. A mask 5 is provided. The mask 5 covers a predetermined region of the non-magnetic support 2 so that the metal magnetic material 7 is obliquely deposited on the non-magnetic support 2 within a predetermined angle range.

An opening window 8 is formed in this mask 5. As a result, the evaporated magnetic metal material 7 is exposed from the opening window 8 without being deposited on the outer peripheral surface of the cooling can 1 around which the non-magnetic support 2 is wound. 2 is vapor-deposited only on the surface. At this time,
The opening window 8 is formed such that the opening width varies in the traveling direction of the non-magnetic support 1. As a result, the time during which the non-magnetic support 1 is exposed from the opening window is changed according to the shape of the opening window, so that the obtained magnetic layer is near the boundary with the region where the metallic magnetic material 7 is not deposited. To have a film thickness distribution. Therefore, the boundary between the region where the magnetic layer is formed and the region where the metallic magnetic material 7 is not deposited is gently formed, so that the heat load at the boundary at the time of vapor deposition can be alleviated and wrinkles are generated. It is possible to prevent the occurrence of distortion that causes

Therefore, the following experiment was carried out by using the manufacturing apparatus having such a configuration and changing the shape of the opening window formed in the mask as shown in Tables 1 and 2 below. That is, a polyethylene terephthalate film having a width of 127 mm and a thickness of 6 μm was used as a non-magnetic support, and this polyethylene terephthalate film was wound around the outer peripheral surface of a cooling can having a diameter of 0.6 m and moved at a tape speed of 14 m / min. On the other hand, oblique vapor deposition was performed to form a magnetic layer with a maximum film thickness of 200 nm. The incident angle of the vapor flow of the magnetic material on the surface of the polyethylene terephthalate film was 45 to 90 ° C.
Set within the range.

The magnetic layer of 300 is formed by such vapor deposition.
After being formed to a length of 0 m and wound on a winding roll having a diameter of 152 mm, it occurred in the vicinity of the boundary between the region where the magnetic layer was formed and the region where the metallic magnetic material was not adhered in this magnetic tape in the wound state. I checked the condition of wrinkles. The results are shown in Tables 1 and 2. The wrinkle state is represented by a value obtained by measuring the height of the portion of the surface of the magnetic tape raised by the wrinkle with a micrometer.

The shape of the opening window of the mask is roughly classified into seven types. Further, various examinations are made by changing the inclination of the hypotenuse of the opening window in the running direction of the non-magnetic support for each shape. did. In this case, as shown in Tables 1 and 2, the tilt amount is indicated by the coordinate system of the distance from the leftmost end of the opening window (horizontal axis) and the distance from the bottom of the opening window (vertical axis). It is represented by the exposed area distribution (calculated value) of the open window.

[0029]

[Table 1]

[0030]

[Table 2]

As shown in Tables 1 and 2, in any of the examples, wrinkles were less likely to occur and good results were obtained. It was also found that the larger the amount of change in the opening width of the opening window (the smaller the inclination of the hypotenuse of the opening window), the less the occurrence of wrinkles.

[0032]

As is apparent from the above description, in the present invention, the magnetic layer is formed on the non-magnetic support by forming the opening window formed in the mask into a trapezoidal shape or a shape corresponding to the trapezoidal shape. Since the boundary between the region where the magnetic material is not deposited and the region where the magnetic material is not adhered is formed gently, it is possible to suppress the heat load applied to the non-magnetic support in these regions during vapor deposition. Therefore, it is possible to prevent a shape abnormality due to the occurrence of strain at the boundary, and to a non-magnetic support material made of a material having a high heat absorption, which has been conventionally unusable, or a base film having an extremely thin film thickness. On the other hand, it became possible to form a good vapor deposition film.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a manufacturing apparatus used in a method for manufacturing a magnetic recording medium of the present invention.

FIG. 2 is an enlarged perspective view of essential parts showing an example of the configuration of a magnetic recording medium manufactured by the method for manufacturing a magnetic recording medium of the present invention.

FIG. 3 is an enlarged perspective view of an essential part showing a configuration of a magnetic recording medium manufactured when vapor deposition is performed using a mask having a rectangular opening window.

FIG. 4 is a plan view showing an example of the shape of an opening window of a mask used in the method of manufacturing a magnetic recording medium of the present invention.

[Explanation of symbols]

 1 ... Cooling can 2 ... Non-magnetic support 5 ... Mask 6 ... Crucible 7 ... Metal magnetic material 8 ... Open window

Claims (1)

[Claims] 1. A method of manufacturing a magnetic recording medium in which a ferromagnetic metal thin film is formed on a non-magnetic support by a vacuum deposition method, the method comprising: forming a ferromagnetic metal thin film on the non-magnetic support; A method of manufacturing a magnetic recording medium, wherein a mask having an opening window is provided in an intermediate portion of a region where vapor deposition is performed, and the opening width of the opening window is varied.