JPH03295031A - Method and apparatus for producing magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent the generation of winding wrinkles by setting the thickness of the vapor deposited film at the end edges in the transverse direction of a web-like base in such a manner that the thickness decreases gradually toward both side edges of the base. CONSTITUTION:The web-like base 4 is partially suspended on the peripheral surface of a main drum 2 acting as a cooling can and a mask 6 is provided apart a specified spacing d opposite to the part where the base is suspended. An evaporated magnetic material in a crucible 8 spreads laterally on the side end edges of the aperture 6a of the mask 6. Since the quantity of the spreading evaporated particles is smaller toward the lateral sides, the thickness of the vapor deposited film is smaller toward the ends. The generation of a step at the boundary between the vapor deposited part and non-vapor deposited part is obviated and, therefore, the generation of the winding wrinkles is obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method and apparatus for depositing magnetic recording material onto a web-like support.

(Prior Art) In the production of magnetic tapes, a method is known in which a metallic magnetic material is deposited on a web-shaped polymer film support to form a thin magnetic recording layer.

In this process, a wide web-like support, which is later slit into tape-like shapes, is suspended on a rotating drum and conveyed, while material evaporated from a vapor source consisting of molten metal in a crucible is placed on top of it in a vacuum. In this case, a mask is placed near the surface of the drum, and the deposition material is deposited onto the support through this mask.

This is because, without a mask, vapor deposition would occur at the end of the drum where no support is suspended, and the vapor deposition material would damage the drum surface.

(Problem to be Solved by the Invention) The mask has a width (here, "width" refers to the length measured parallel to the axis of the drum) that is smaller than the width of the support, and the mask is The vapor deposition layer on the support is formed inward from a portion several layers to several tens of meters away from the edge (side edge) in the width direction of the support.

Therefore, the support has a vapor-deposited portion made of a vapor-deposited film of a constant thickness over substantially the entire width, and has undeposited portions on both side edges where no vapor deposition is performed. For this reason, when the support leaves the drum and reaches the next exit roll after vapor deposition, wrinkles occur near the boundary between the vapor-deposited part and the undeposited part of the support, and these wrinkles do not disappear during transportation until winding. This may cause wrinkles in the wrapping and cause product defects.

Therefore, an object of the present invention is to provide a method and apparatus for manufacturing a magnetic recording medium that does not cause such winding wrinkles.

(Means for Solving the Problems) In the present invention, during the above-mentioned vapor deposition, the thickness of the vapor-deposited portion gradually decreases from the vapor-deposited portion toward the edge so that no step is formed at the boundary between the vapor-deposited portion and the undeposited portion. It is characterized by the following.

That is, the method for manufacturing a magnetic recording medium according to the present invention includes depositing a magnetic recording material on a web-like support conveyed on a drum to form a deposited film on the support. The method is characterized in that the vapor deposition is performed so that the thickness of the vapor-deposited film at the edge in the width direction of the web-like support is gradually reduced toward both side edges of the support.

The apparatus for manufacturing a magnetic recording medium according to the present invention also includes a rotating drum that transports a web-like support suspended on the circumferential surface, and a web-shaped support that is conveyed along the circumferential surface at a constant interval of 68 or more from the circumferential surface of the rotating drum. and a vapor deposition means for vapor depositing a magnetic recording material onto the web-like support on the peripheral surface of the rotating drum through the mask, the mask having an axial length in the axial direction of the drum. Furthermore, the width of the support is smaller, and the width of the mask is smaller than the width of the support.

That is, the distance between the mask and the drum is increased to a certain extent, and at both ends of the mask, the evaporation material from the evaporation source that is long in the width direction is evaporated little by little toward the edge of the web due to the wrapping action of evaporated particles. It is characterized by the following.

(Operations and Effects) According to the method for manufacturing a magnetic recording medium of the present invention, no step portion is formed at the boundary between the deposited portion and the undeposited portion, so that the occurrence of the winding wrinkles as described above can be prevented. Further, according to the apparatus according to the present invention, since the mask is provided with a distance of 6M or more between the cooling can and the cooling can as described above, the vapor deposition particles wrap around to the sides at both sides of the opening of the mask. It can be obtained with a deposited film of decreasing thickness at the edges of the web.

Note that it is preferable that a portion whose thickness gradually decreases from a deposited portion having a constant thickness extend to the end of the web, and that the undeposited portion be almost completely eliminated.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

1 and 2 show an example of an apparatus for carrying out the method according to the invention. A web-like support 4 is partially suspended on the main drum 2 acting as a cooling can, and a mask 6 is provided at a constant interval d of 6 mm or more opposite the suspended part. . This mask 6 has a rectangular opening right 6a, and the width W of this opening 6a is
m is smaller than the width Wd of the drum 2. The width Wd of the web-like support 4 is larger than the width Wm of the drum 2. A crucible 8 is placed below this mask 6 as an evaporation source for the magnetic material. This crucible 8 has a width sufficient to cover the width of the opening 6a of the mask 6.

The magnetic material in the crucible 8 is scanned with an electron beam,
This melts and vaporizes the magnetic material. The evaporated material wraps around to the side at the side edge of the opening 6a of the mask 6, as shown by the two-dot chain line in FIG. As shown in the figure, the thickness of the deposited film 10 decreases toward the ends. That is, the vapor deposited film 10 consists of a main vapor deposition part 10a having a constant thickness covering almost the entire support 4, and a vapor deposition edge part 10b having a gradient thickness at the side edge of the support 4.

In the case of this type of thin film magnetic tape, the distance d between the mask 6 and the circumferential surface of the drum 2 must be at least 6 m. If it is smaller than this, the width of the evaporation edge 10b becomes too small, and the evaporation area and The steps formed between the film and the vapor deposition part cause the above-mentioned curling wrinkles. If this interval is 6 mm or more, there is no problem, but the upper limit is naturally determined by the positional relationship between the mask 6 and the drum 2. That is, the mask 6 must be close to the drum 2 to such an extent that the evaporated material does not fly out from the side edges of the support 4 and adhere to the circumferential surface of the drum. Therefore, when the difference between the width Wli of the opening of the mask 6 and the width wb of the support body 4 is large, the mask 6 may be separated from the circumferential surface of the drum 2 considerably, but when this difference is small, the mask 6 is must be close to the circumferential surface of the

Note that in the conventional device, this distance d was about 4 m.

Specifically, based on the above method, an apparatus was constructed under the following conditions, and the experiment was carried out.

Ultimate vacuum 2. OX 10' Torr
Evaporation vacuum degree 6. OXIO''' Torr
Conveyance speed 100 TrL/sin Support width (Wb) 5QQ H1 mask opening width (
Wm) 480 m Distance between mask and drum 1
0m Electron gun output 70 Kν×2 Deposited film thickness
2000 people evaporation material Co Ni O support thickness
10 μm When an experiment was conducted using these specifications, a vapor deposition edge on the side edge of the vapor deposited film having a thickness gradient outward from a 10 m inner side edge portion of the support was well formed.

In the above embodiment, the mask 6 is arranged at a fixed position with respect to the drum 2, but by finely vibrating the mask 6 in a direction parallel to the rotation axis of the drum 2, the deposited film can be removed. It is also possible for the thickness to taper off at the edges. This also allows the method of the invention to be implemented. That is, if the mask 6 is vibrated in the axial direction so as to draw a sine wave or a triangular wave, the amount of the vapor deposition material gradually decreases outward at the edge of the vapor deposition part, and the method of the present invention can be carried out. It can be realized.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of an apparatus for carrying out the method of manufacturing a magnetic recording medium of the present invention, FIG. FIG. 2... Rotating drum (cooling can) 4... Web-like support 6... Mask 6a...
・Mask opening 8... Crucible 10... Vapor deposited film 10a... Vapor deposition main part 10b... Vapor deposition edge FIG.

Claims (1)

[Scope of Claims] 1) A method for producing a magnetic recording medium, comprising depositing a magnetic recording material on a web-like support conveyed on a drum to form a deposited film on the support, wherein the web-like support A method for producing a magnetic recording medium, characterized in that the vapor deposition is performed so that the thickness of the vapor-deposited film at the edge in the width direction of the support is gradually reduced toward both edges of the support. 2) A rotating drum that transports a web-like support suspended on its circumferential surface, a mask having openings extending along the circumferential surface at a constant interval of 6 mm or more from the circumferential surface of the rotating drum, and comprising a vapor deposition means for vapor depositing a magnetic recording material onto the web-like support on the peripheral surface of the rotating drum through a mask, the width of the support being smaller than the length in the axial direction of the drum; A manufacturing apparatus for a magnetic recording medium, wherein the width of the mask is smaller than the width of the support.