JPH0198122A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To easily provide an easy magnetization characteristic to the concentrical direction of a magnetic layer by passing current to the thin metallic film on a high-polymer molding substrate or metallic substrate to generate a magnetic field, thereby orienting the magnetic layer. CONSTITUTION:After the thin metallic film 12 is formed on the substrate 10 consisting of the high-polymer molding, the magnetic layer 14 is coated thereon. Uncoated parts are provided to the outside circumferential part and inside circumferential part of the substrate at this time. Electrodes 16, 18 are brought into contact with the uncoated outside circumferential part and inside circumferential part and the current is passed in the radial direction of the disk while the thin magnetic film is not dried yet. The magnetic field H is then generated in the concentrical direction and the orientation is executed. The recording medium produced by this production process has, therefore, orientability and the max. magnetic flux density, coercive force and squareness ratio, etc., are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a magnetic recording medium such as a magnetic disk for an external memory of a computer.

[Problems to be Solved by the Prior Art and Inventions 1 Magnetic recording media are broadly divided into long magnetic tapes for audio or video, and magnetic disks such as 70 disks or hard disks. Orientation takes place in the layers. By the way, a magnetic disk usually performs a relative rotational movement with a magnetic head, and magnetic recording is performed in a concentric direction. Therefore, it is most preferable for the magnetic layer to have magnetic anisotropy in the concentric direction. For example, when acicular γ-Fe203 is used as the magnetic material, the acicular γ-Fe203 is in the concentric direction.
-Fe20=Magnetic recording and reproduction can be performed most efficiently when the long sleeves are oriented. However, in conventional magnetic disks, it was extremely difficult to provide easy magnetization in the concentric direction, so the magnetic disks were non-oriented.

Means and Effects for Solving Problem E and α 1 As a result of the inventors' intensive investigation to orient the magnetic material of the magnetic disk in the concentric direction, the present inventors found that by passing a current through the magnetic disk having the magnetic material, The present invention was completed by discovering that a magnetic field can be generated in a concentric direction to achieve orientation.

That is, according to the present invention, after a magnetic layer is formed by coating a magnetic material on a disk-shaped polymer molded substrate or a disk-shaped metal substrate provided with a metal thin film, the magnetic layer is not dried. A method of manufacturing a magnetic recording medium is provided, in which a magnetic field is generated by passing a current through the metal thin film or the metal substrate between the magnetic layers, and magnetic orientation is performed in a concentric direction within the magnetic layer.

The present invention generally applies Ampere's law, which states that when a current flows, a magnetic field is generated in the direction of rotation of a right-handed screw relative to the direction of the current. That is, by passing a direct current in the radial direction of a metal thin film on a metal substrate or a polymer molded substrate, a concentric magnetic field is generated, thereby causing orientation in the magnetic layer.

[Example 1] Hereinafter, an example of the method for manufacturing a magnetic recording medium of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view for explaining one embodiment of the present invention. First, a metal (conductive) thin film 12 is provided on one surface of a substrate 10 made of a polymer molded product.The material of the metal may be aluminum, copper, silver, or any other conductive material, and the choice of material depends on the cost. The method for producing the metal thin film 12 may be determined as appropriate after considering durability, physical characteristics, etc.
Any method such as vapor deposition, sputtering, ion blating, electroless plating, etc. is fine, but gold! ! 4. The thickness of the thin film 12 is set to a necessary thickness in consideration of the thickness dependence of electrical resistance. Note that if the base body 10 is a conductive material, it is not necessary to provide the thin metal WA 12 described above.

The above metal thin! 112 on the substrate 10, the magnetic layer 14 is applied thereon. At this time, the disk-shaped substrate 1
An uncoated portion is provided at the outer circumferential portion and inner circumferential portion of 0. When the magnetic coating film is not dry, electrodes 16 and 18 are brought into contact with the uncoated outer and inner circumferential portions and a current is passed in the radial direction of the disk, a magnetic field H is generated in the concentric direction, and orientation is performed. . When performing orientation over the entire magnetic disk, when the magnetic disk is rotated 111i:,
If the magnetic coating film flows depending on the rotational speed of the magnetic disk, it is sufficient to fix the magnetic disk and rotate the electrodes 16 and 18.

The magnitude of the magnetic field H generated by the current I is inversely proportional to the distance from the current I, but in the case of the above method, since the magnetic layer 14 is in contact with the metal thin film 12, a large magnetic field H is generated with a relatively small current I. Occur.

Next, the manufacturing method in this example will be explained in more detail together with a comparative example.

As shown in FIG. 1, aluminum 12 is applied to a 70μ-thick polyester base film 10 to a thickness of 1 by vacuum deposition.
Deposit μII. After punching this out into a disk shape, a magnetic paint composed of γ-Fe20= and a polymeric binder is applied to this substrate. The magnetic layer l coated in this way
When the substrate 114 is in an undried state, the substrate 1 is removed as shown in FIG.
Current 5 through electric ff116.18 while rotating 0
Orientation was performed by flowing ^.

Thereafter, a polishing treatment was performed, and a curing reaction was performed by leaving it at 40° C. for 48 hours to produce a floppy disk.

Comparative Example Using the same method and conditions as above, that is, aluminum 12 was applied to the polyester base film 10 using FkML.
, after punching this into a disk shape, 7-Fe2 is applied to this base.
e, and a magnetic paint composed of a polymer binder is applied,
A magnetic metal 14 was formed. After this, unlike the case described above, no current was applied, that is, no magnetic field orientation was applied, and then calender treatment was performed, and the material was left to stand at 40° C. for 48 hours to allow a hardening reaction to occur, producing a 70-tupee disk.

The evaluation results of the orientation characteristics of the floppy disks produced in the above Examples and Comparative Examples are shown in the table, and it can be seen from the results that the Examples have better orientation.

Figure fjS2 is a perspective view for explaining an embodiment of the pond of the present invention. As shown in FIG. 28, a large number of metal thin films 12a extending in the radial direction are provided at predetermined intervals on a non-conductive substrate 10 made of a molded polymer or the like, and a magnetic layer 14 is applied thereon. In this embodiment, as in the previous embodiment, when coating the magnetic layer 14, uncoated portions are provided on the outer and inner circumferences of the metal thin film 12a (the coated magnetic layer 14 and the uncoated portions are (not shown). In addition, magnetic N14
The magnetic paint forming the magnetic paint enters the recesses between the thin metal films 12a provided at predetermined intervals, and the surface of the paint film becomes smooth.

In the previous example, it was appropriate to provide only one pair of electrodes from the viewpoint of alignment characteristics, but in this example, as shown in the Pt5ZB diagram, multiple pairs of electrodes 16 and 18 are used, and these are connected in series. . That is, a plurality of + side electrodes 16i116
b, 16c and a plurality of one side electrodes 18a, 18b.

18c are arranged in pairs, facing each other in the concentric direction of the base 10, and are connected to adjacent opposite electrodes by conductors #i20, forming a series electrode as a whole. When a current I is applied to a plurality of radially extending metal thin films 12 & provided at predetermined intervals using electrodes having such a configuration, the range in which the magnetic field (1) is generated becomes wider, thereby increasing the orientation efficiency.

[Effects of the Invention] As is clear from the above description, in the method for manufacturing a magnetic recording medium according to the present invention, a magnetic field is generated by passing a current through a metal thin film on a polymer molded substrate or a metal substrate for orientation. becomes possible. Therefore, the recording medium manufactured by the manufacturing method of the present invention has an orientation, and has excellent features such as improved maximum magnetic flux density (Bm), coercive force (He), squareness ratio (Rs), etc. , the industrial applicability of the present invention is extremely large.

[Brief explanation of the drawing]

Fig. 1 is a perspective view for explaining one embodiment of the present invention, Fig. 28 and Fig. 2B show other embodiments of the present invention, and Fig. 28 shows this embodiment. FIG. 2B is a partial perspective view for explaining the manufacturing method of , and FIG. 2B is a plan view showing the arrangement of a plurality of electrodes used in this example. 10... Substrate, 12.12a... Metal thin film, 14... Magnetic layer 16.16a, 16b, 16c118.18a,
18b, 18c-electrode 20...Conducting wire inventor Horiguchi Kofuji Kuniharu Ki

Claims (3)

[Claims] (1) After coating a magnetic material on a disk-shaped polymer molded substrate or a disk-shaped metal substrate provided with a metal thin film to form a magnetic layer, the metal thin film is formed while the magnetic layer is not dried. Alternatively, a method for manufacturing a magnetic recording medium in which a magnetic field is generated by passing a current through the metal substrate, and magnetic orientation is performed in a concentric direction within the magnetic layer. (2) When passing the current, the substrate is rotated while flowing a direct current in the radial direction of the substrate using electrodes that contact the inner and outer peripheries of the metal thin film or the metal substrate, respectively. A method for manufacturing a magnetic recording medium according to claim 1. (3) A large number of metal thin films extending in the radial direction are provided at predetermined intervals on the polymer formed substrate, the magnetic layer is applied thereon, and the metal thin films are connected in series and arranged concentrically as the electrodes. Claim 1, wherein the base body is rotated using a plurality of pairs of electrodes that contact the inner and outer circumferential portions of the metal thin film provided at predetermined intervals. A method of manufacturing the magnetic recording medium described above.