JPS6016009B2 - Manufacturing method and equipment for magnetic tape or magnetic sheet - Google Patents

Description

[Detailed Description of the Invention] Field of Application of the Invention The present invention relates to a method for manufacturing a magnetic tape or a magnetic sheet, and more particularly, the present invention relates to a method for manufacturing a magnetic tape or a magnetic sheet, and more particularly, it relates to a method for manufacturing a magnetic tape or a magnetic sheet, and more particularly, it relates to a method for manufacturing a magnetic tape or a magnetic sheet, and more particularly, it relates to a method for manufacturing a magnetic tape or a magnetic sheet. The present invention relates to a method for manufacturing a magnetic tape or a magnetic sheet.

The demand for higher density magnetic recording has become stronger in recent years, and as a means to meet this demand,
Recording the strength of magnetization perpendicular to the surface of a magnetic recording medium.
A so-called perpendicular magnetization recording method has been proposed.

By the way, in order to fully utilize the features of this method,
There is a need to develop a magnetic recording medium with an axis of easy magnetization perpendicular to the surface of the pus. As a magnetic recording medium having such characteristics, for example, C is recorded on a heat-resistant plastic film.
A recording medium on which o-Cr is deposited by high-frequency sputtering has been proposed, but there are problems with its productivity and it has not yet been put into practical use. On the other hand, in the magnetic tape conventionally used in the normal in-plane magnetization recording method, as shown in FIG. By applying an in-plane magnetic field using an in-plane magnetic field applying device 5 before drying,
It is manufactured by orienting acicular magnetic powder in the direction of the magnetic field.

Therefore, in order to manufacture a magnetic tape having an axis of easy magnetization perpendicular to the film surface, it is easy to conceive that the applied magnetic field should be perpendicular to the tape surface. By the way, in a conventional magnetic tape manufacturing apparatus, it has been found that sufficient orientation cannot be obtained by simply changing the direction of application of the magnetic field so that it is perpendicular to the tape surface.

As related to the present invention, for example, Tokukan Sho 52-7
Publication No. 8403 can be mentioned.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a method for applying a magnetic powder coating that eliminates such drawbacks.

Another object of the present invention is to provide an apparatus for manufacturing a magnetic tape or magnetic sheet having the above characteristics and capable of coating. Still another object of the present invention is to provide a means for manufacturing the above-mentioned oriented magnetic tape or magnetic sheet having uniform orientation. General description of the invention When manufacturing a magnetic tape or magnetic sheet whose axis of easy magnetization is perpendicular to the film surface, conventional magnetic tape coating equipment simply changes the direction of the orienting magnetic field from within the film surface to perpendicular to the film surface. The first reason is that when passing through the doctor blade, the acicular magnetic powder is aligned in the traveling direction of the base film, and this causes the orientation magnetic field to be applied to the area. The problem lies in fixing it to some extent until it reaches .

The present invention aims to alleviate this situation and to further positively orient the magnetic powder in a direction perpendicular to the film surface by creating a difference in the pressure between the doctor blade that applies the magnetic powder-containing paint and the roller. A magnetic field is applied in a direction perpendicular to the film surface at the stage when a paint containing magnetic powder is applied to a plastic base film. Such application is possible, for example, by configuring at least a portion of the facing surfaces of the doctor blade and roller with a magnetic material, and generating a magnetic potential between the facing portions using a permanent magnet or an electromagnet. . Incidentally, the edges of conventionally used doctor blades are usually not chamfered. Providing a level difference between the doctor blade with such a sharp edge and the surface of the roller causes magnetic flux to concentrate at the edge and generates a strong magnetic field, which is preferable from the standpoint of orientation of the magnetic powder. However, on the other hand, there is a tendency for magnetic powder to be attracted to the edge and stick to it.
The edge of the blade is not uniform in the width direction, that is, in the width direction of the base film, resulting in a problem that the magnetic powder in the coating film is not uniformly dispersed or oriented. One way to solve this problem is to chamfer or round the edges of the doctor blade. Another way to solve this problem is to make at least the edge of the doctor blade from a non-magnetic material. The strength of the magnetic field applied perpendicularly to the film surface is 4mMs or more (
However, Ms is preferably the saturation magnetization strength of the magnetic powder.
It is usually 1,000 Oe or more, preferably 2,000 Oe or more, but the effect can be seen even with a few hundred Oe.

Example Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 2 shows a schematic diagram of an embodiment of the present invention.

A portion has been cut away to make the structure easier to see. 2 is a doctor blade integrated with a receiving portion 6 for receiving magnetic powder paint, and 3 is a roller, both of which are made of magnetic material.

The roller 3 is attached to the base 11 at the shaft portion 8 via the sleeve 9.
It is supported by a bearing 10' made of a magnetic material fixed to. The doctor blade 2 is fixed to the upper end of the bearing 10 by adhesive or other means via two permanent magnets 7 whose lengths are precisely set. At this time, 2
All of the permanent magnets 7 are magnetized in the same direction in the vertical direction. Thus, doctor blade 2 and roller 3
A magnetic potential difference can be created between them. In this embodiment, the length of the permanent magnet 7 is precisely machined in order to control the gap between the doctor blade and the roller at a constant level. However, if the gap is controlled by other methods, the permanent magnet When precision machining is not required and there is a difference in coefficient of thermal expansion between the permanent magnet and the doctor blade, loaf, bearing, etc., it is better to seek other means for controlling the gap. As the magnetic material for the doctor blade and roller, it is best to use high magnetic permeability materials such as silicon steel, ferritic and martensitic stainless steel, or heat-resistant steel.
In some cases, the blade material is semi-steel magnetic material,
Permanent magnetic materials such as KS steel and MK steel may also be used. As materials for the roller shaft and bearings, silicon steel, martensitic or ferritic stainless steel, heat-resistant steel, carbon steel for machine structures, etc. are preferably used in view of requirements for toughness, wear resistance, and the like. However, it is generally desirable that the materials for the rattan and bearing of the roller be different. Permanent magnet materials include doctor blade, loaf,
It is necessary to select a material that is more durable than the materials used for the roller shaft, bearings, etc., and can be selected from KS steel, MK steel, NKS steel, alnico, etc. Note that the same effect can be obtained by making the magnet part of a soft magnetic material, winding a coil around it, and passing a current through this. Furthermore, since wear of bearings and roller shafts directly affects coating thickness, anti-wear measures are necessary. As a countermeasure against this problem, it is extremely effective to inject a magnetic material into the bearing.
FIG. 3 is a partial cross-sectional view of another embodiment of the invention.

The feature of this embodiment is that the front edge of the doctor blade in the first embodiment is rounded 13 as shown in FIG.
This prevents uneven agglomeration of the magnetic powder at the edge portion and provides a uniform coating film. Such edge treatment is not necessarily rounding, but may be replaced by appropriate chamfering. Note that it is desirable that the rear edge portion 14 be subjected to similar edge treatment depending on the moving speed of the base film and the type and concentration of the binder of the magnetic powder paint. Note that the magnetic field applying device 5 outside the doctor blade is oriented in the same direction as the magnetic field applied to the doctor blade. FIG. 4 is a partial cross-sectional view of yet another embodiment of the invention.

The feature of this embodiment is that the magnetic powder paint receiving portion 15 including the edge portion is formed of a non-magnetic material so that the magnetic edge portion of the doctor blade is not directly exposed to the magnetic paint reservoir. The rear part of the part is made of a magnetic material as shown in the above embodiment, thereby preventing uneven aggregation of the magnetic powder at the edge part. In this case, it is also effective to round or chamfer the rear edge, and this can also be done by attaching a thick non-magnetic material that is in contact with the rear magnetic edge. can. In this example, the magnetic powder paint receiving portion was entirely made of non-magnetic material, but the same effect could be obtained by attaching a suitable non-magnetic material to the edge portion in the first example. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a conventionally known magnetic powder coating device;
FIG. 2 is a sketch with a partial cutout of one embodiment of the invention, FIG. 3 is a partial cross-sectional view of another embodiment of the invention, and FIG. 4 is a partial cross-sectional view of still another embodiment. FIG. Figure 1 Figure 3 Figure 2 Figure 4

Claims (1)

[Scope of Claims] 1. A method for manufacturing a magnetic tape or magnetic sheet in which a magnetic powder-containing paint in which magnetic powder is dispersed in a binder is applied onto a plastic base film using a coating machine that combines a doctor blade and a roller. A method for manufacturing a magnetic tape or magnetic sheet, characterized in that a magnetic potential difference is provided between the doctor blade and the roller. 2. In a coating machine that combines a doctor blade and a roller for applying a magnetic powder-containing paint in which magnetic powder is dispersed in a binder to a plastic base film, at least a portion of the opposing members of the doctor blade and roller are 1. An apparatus for manufacturing a magnetic tape or magnetic sheet, comprising a magnetic material and comprising means for generating a magnetic potential difference between the opposing parts. 3. The magnetic tape or magnetic sheet manufacturing apparatus according to claim 2, wherein the edge portion of the doctor blade is chamfered or rounded. 4. The magnetic tape or magnetic sheet manufacturing apparatus according to claim 2, wherein the edge portion of the doctor blade is made of a non-magnetic material.