JPS61158030A - Production of magnetic disk medium - Google Patents

Abstract

PURPOSE:To obtain surely an extremely thin and high-density magnetic coated film without being affected by the surface of a substrate by coating a magnetic paint on the substrate, simultaneously impressing a horizontal magnetic field, and impressing a horizontal or a vertical magnetic field on the remaining surface of the substrate after the magnetic coated film is dried to some extent. CONSTITUTION:A horizontal magnetic field is impressed by the first magnetic poles 5 and 6 and 7 and 8 from the time when the coating of a magnetic paint is started. Consequently, before the magnetic paint is dried, magnetic powder is drawn to the surface side, and surely collected on the surface to increase the density of the magnetic powder in the surface part of the magnetic coated film. The movement of the magnetic powder to the outer periphery of the substrate by teh centrifugal force and the sweeping off the powder from the periphery are surely prevented, and the magnetic powder is held on the substrate to further increase the density of the magnetic powder. Since the magnetic powder is moved to the surface side and oriented before the magnetic paint is dried, the treatment is carried out rapidly in a short time, and the working efficiency is increased. A magnetic field is impressed on the remaining surface of a substrate 4 by the second magnetic poles 9 and 10 and the third magnetic poles 11 and 12, hence the magnetic field is impressed on the whole surface of the substrate 4, and the magnetic powder is moved to the surface side and oriented more surely.

Description

Detailed Description of the Invention [Field of Industrial Application] A magnetic disk device is used as an external storage device of a data processing system, and the present invention is directed to a magnetic disk medium used as a storage medium in this magnetic disk device. Regarding the manufacturing method. More specifically, the present invention relates to a method for producing a magnetic coating film formed on the surface of a substrate of a magnetic disk medium.

[Conventional technology]

As shown in FIG. 7, a magnetic recording medium in a magnetic disk device is produced by coating a substrate 1 such as an aluminum disk with a magnetic paint made by kneading magnetic powder and a synthetic resin as a binder, and then drying the mixture. It is obtained by forming a magnetic coating film 2 on the surface of a substrate.

Incidentally, in recent years, magnetic disk devices have rapidly increased in data recording density and capacity, and there has been a trend toward smaller devices in terms of high speed and economical efficiency. In order to obtain a magnetic disk medium with a high recording density that satisfies these demands, it is necessary to make the magnetic coating used as a recording medium as thin as possible and to increase the dispersion density of magnetic powder. Even if the surface of the substrate is finished with high precision, it is impossible to completely eliminate the small protrusions 3. Therefore, even if only the magnetic coating film 2 is made thin, the unevenness of the substrate surface will affect the magnetic coating film 2, so it is extremely difficult to obtain a magnetic coating film with a thickness of 0.5 μm or less and without defects. It's a technique.

[Problem that the invention seeks to solve]

To solve this problem, attempts were made to first form a layer of synthetic resin only, and then form only an extremely thin magnetic layer on top of it, so that the unevenness of the substrate would not affect the surface magnetic layer, but the coating process increased. Not only that, but the increase in the number of steps also causes various problems, making it difficult to obtain defect-free substrates, and the process has not been smoothly put into practical use. Moreover, if the amount of magnetic powder mixed into the synthetic resin used as a binder is increased, problems such as a decrease in bonding force occur, and it is difficult to increase the dispersion density of the magnetic powder to achieve a high density.

The technical problem of the present invention is to eliminate such problems in conventional magnetic disk media and to reliably obtain an extremely thin, high-density magnetic coating without being affected by the substrate surface. .

[Means for solving problems]

The technical means of the present invention taken to solve this problem is to coat a non-magnetic circular substrate with a magnetic paint made by kneading magnetic powder and a synthetic resin as a binder. A method of manufacturing a magnetic disk medium in which a magnetic coating film is formed on a substrate, wherein N and Sl pairs of magnetic poles are arranged on each surface of the substrate with a slight gap between the substrate surface and the N. The poles and S poles are arranged parallel to each other, and the gap between the N and S poles is oriented in the radial direction of the board. These magnetic poles allow a horizontal magnetic field to be applied to the magnetic coating film at the same time as applying magnetic paint to the board. is applied, and after the magnetic coating film has dried somewhat, in addition to applying the horizontal magnetic field, a magnetic pole in the form of two halves of the magnetic pole, which is shaped to sandwich the remaining surface of the substrate, is moved toward the substrate side to form a magnetic pole. A method is adopted in which a horizontal or vertical magnetic field is applied to the remaining surface of the substrate with the substrate sandwiched between them.

[Effect]

According to this technical means, magnetic paint is first applied to both sides of the substrate with N, 31 pairs of magnetic poles arranged in the radial direction on both sides of the substrate. Simultaneously with the application of the magnetic paint, the magnetic poles are excited, and a horizontal magnetic field is applied to the applied magnetic paint. This magnetic field is applied uniformly from the inner circumferential side to the outer circumferential side of the substrate.

Furthermore, since the substrate is rotating, a horizontal magnetic field is applied to the entire surface of the substrate. Therefore, by applying a horizontal magnetic field when the magnetic paint is in an undried state immediately after being applied, the magnetic powder is easily oriented horizontally and the axis of easy magnetization is aligned in the circumferential direction. At the same time, it is attracted to the surface of the magnetic coating and concentrated.

Furthermore, in order to reduce the film thickness, the applied magnetic paint is cut and dried to shake off the excess magnetic paint, but in the conventional method, the magnetic powder is also shaken off.
Although the density of the magnetic powder decreased, in the method of the present invention, a horizontal magnetic field is applied immediately after application, and the magnetic powder is attracted.
The magnetic powder remains without being shaken off from the substrate, increasing the density of the magnetic powder.

Because magnetic paint is highly volatile, it begins to dry as soon as it is applied, but immediately after shaking it off, the two-part magnetic pole moves toward the board, sandwiching the remaining surface of the board, and the remaining surface of the board is removed. A horizontal or vertical magnetic field is applied to the plane of the By applying a magnetic field to the remaining large surface, the magnetic powder is more reliably concentrated on the surface of the magnetic coating film, and the density of the magnetic powder on the surface is increased. Note that when the magnetic field applied after the shake-off is a vertical magnetic field, the substrate passes through the vertical magnetic field applying section and the horizontal magnetic field applying section alternately, and the horizontal magnetic field and the vertical magnetic field are applied alternately. Therefore, by first stopping the application of the vertical magnetic field and finally applying only the horizontal magnetic field using the magnetic poles that have been applied since before shaking off, all of the magnetic powder is oriented horizontally.

〔Example〕

Next, how the method for manufacturing a magnetic disk medium according to the present invention is actually implemented will be explained using examples. FIG. 1 is a plan view and a front view showing a state in which a magnetic disk medium is subjected to orientation processing by the manufacturing method of the present invention, and FIG.
is a circular board.

5 and 6.7 and 8 are the first magnetic poles, respectively;
7 and 8 are paired. The spacing between the magnetic poles 5 and 6, and 7 and 8 is constant over the entire length, and the gap is arranged in such a way that it faces in the radial direction of the substrate 4. Also, magnetic pole 5
．． 6 and magnetic poles 7.8 and the substrate 4 are opposed to each other with a slight gap therebetween.

9 and 10 are second magnetic poles, and 11 and 12 are third magnetic poles. The second magnetic poles 9 and 10 are arranged to face the substrate surface so as to sandwich approximately the right half of the remaining surface of the substrate 4 . Further, the third magnetic poles 11 and 12 are arranged to face the substrate surface so as to sandwich approximately the left half of the remaining surface of the substrate 4.

The second magnetic poles 9 and 10 and the third magnetic poles 11 and 12 are capable of reciprocating movement toward the center of the substrate 4, as shown by arrows a1 and a2.

Although the excitation coil is omitted in FIG. 1 to make it easier to understand the positional relationship of each magnetic pole, the excitation coil is shown in FIG. 2 (a).

FIG. 3 is a plan view and a front view showing a method for performing orientation using the magnetic poles, and FIG. 4 is a time chart showing the process of producing a magnetic coating film.

First, as shown in FIG. 3, the second magnetic pole 9.10 and the third magnetic pole 11.12 are retracted from the substrate 4 so that they do not interfere with the application of the magnetic paint by the nozzle 13 and the sprinkling drying. Then, by energizing the excitation coils 14 and 15 and moving the nozzle 13 from the inner circumferential side to the outer circumferential side of the substrate 4 while rotating the substrate 4, as shown in FIG. 4(a), Magnetic paint is applied to both sides of the substrate 4.

The magnetic paint ejected from the nozzle 13 spreads over the entire surface of the substrate 4 due to the centrifugal force of the substrate 4, and is coated on the entire surface.

At the same time that the magnetic paint is applied to the substrate 4 in this manner, a horizontal magnetic field parallel to the substrate surface is applied by the first magnetic poles 5.6 and 7.8. Therefore, as shown in FIG. 5(A), a magnetic flux 18 is generated parallel to the surface of the magnetic coating film, and the magnetic particles 2a are attracted along this magnetic flux 18.

As a result, the magnetic powder 2a in the magnetic paint is oriented horizontally and in the circumferential direction of the substrate 4, and is attracted and held so that the magnetic powder does not move toward the outer periphery due to centrifugal force.

Next, as shown in FIG. 4 (bl), the rotation speed of the substrate 4 is increased to shake off the excess magnetic paint attached to the substrate 4. In this way, the rotation speed of the substrate 4 is increased and the excess magnetic paint is shaken off. The paint is shaken off, but the first magnetic poles 5.6 and 7
．． Since the magnetic powder is attracted and held by the magnetic powder 8, the magnetic powder remains on the substrate 4 without being shaken off, and the magnetic powder density of the magnetic coating film becomes high.

After the shooting process, as shown in FIG. 4 (C1), the rotation speed of the substrate 4 is reduced, and the second magnetic poles 9, IO and third magnetic poles 11 and 12 are moved onto the substrate 4 and the first As shown in the figure, the remaining surface of the substrate 4 is sandwiched.Then, the excitation coil 1
By energizing 6.17, the second magnetic pole 9.10 and the third
A vertical magnetic field is applied to the remaining surface of the substrate 4 by the magnetic poles 11 and 12, and a vertical magnetic flux 19 is generated as shown in FIG. 5(b). Since a horizontal magnetic field is applied to the first magnetic poles 5.6 and 7.8, as the substrate 4 rotates, each surface of the substrate 4 receives a horizontal magnetic field and a vertical magnetic field alternately. While repeating the motion of lying horizontally as shown in 28... in Figure 5 (b) and standing vertically as shown in 2b..., they are further attracted to the surface of the magnetic coating film.

Finally, the excitation coils 16.17 of the second magnetic pole 9.10 and the third magnetic pole 11.12 are de-energized and the application of the vertical magnetic field is stopped. Only a horizontal magnetic field is applied by the first magnetic poles 5.6 and 7.8. Or, as shown in Figure 2 (b), reduce the spacing between magnetic poles 9-6, 10-8, 11-5, and 12-7, and reverse the direction of the current in coils 16 and 17 to excite. By doing so, the polarity of each of the magnetic poles is reversed. Then, as shown in FIG. 5(c) or (e), all the magnetic powder falls horizontally and moves toward the surface of the magnetic coating, resulting in an ideal state.

The alignment process is thus completed, and the substrate 4 is again rotated at high speed as shown in FIG. 4 (dl) to perform main drying.

By making the second magnetic poles 9 and 10 the same polarity and making the third magnetic poles 11 and 12 the same polarity as shown in Fig. 6, a repulsive force is created between the magnetic poles 9 and 10 and between the magnetic poles 11 and 12. occurs, and as shown in Figure 5 (
As shown in (d), a magnetic flux 20 parallel to the surface of the magnetic coating is generated on the surface of the substrate 4. Therefore, a horizontal magnetic field is applied to the magnetic powder on the surface of the magnetic coating film, and the magnetic powder falls horizontally. Therefore, together with the horizontal magnetic field from the first magnetic poles 5.6 and 7.8, the horizontal magnetic field acts on the entire surface of the magnetic coating, and as shown in Figure 5(d), the magnetic powder on the entire surface of the magnetic coating is are reliably oriented horizontally and attracted toward the surface, increasing the magnetic powder density on the surface.

〔Effect of the invention〕

As described above, according to the present invention, the first magnetic poles 5.6 and 7.
8, by applying a horizontal magnetic field from the beginning of applying the magnetic paint, the magnetic powder is attracted to the surface before the magnetic paint dries, thereby ensuring that the magnetic powder is concentrated on the surface and forming a magnetic coating film. It is possible to increase the density of magnetic powder on the surface. In addition, it reliably prevents the magnetic powder from moving to the outer periphery of the board due to centrifugal force and being captured, and by keeping it on the board,
Magnetic powder density can be further increased. Furthermore, since the magnetic powder is moved and oriented toward the surface before the magnetic paint dries, processing can be carried out quickly and in a short time, and work efficiency can be improved. Second magnetic pole 9.10 and third magnetic pole 11
．． 12, a magnetic field is also applied to the remaining surface of the substrate 4, and by applying the magnetic field to the entire surface of the substrate 4, the magnetic powder is more reliably moved and oriented toward the surface side.

[Brief explanation of drawings]

FIG. 1 is a plan view and a front view showing the arrangement of magnetic poles used in the method of manufacturing a magnetic disk medium according to the present invention, and FIG. 2 (A)
(B) is a front view showing a state in which an excitation coil is mounted on each magnetic pole, FIG. 3 is a plan view and front view showing a method for manufacturing a magnetic disk medium, and FIG. 4 is a flowchart showing a manufacturing process for a magnetic disk medium. Fig. 5 is a cross-sectional view showing the state of magnetic powder in the magnetic coating film, Fig. 6 is a front view showing another embodiment of the second and third magnetic poles, and Fig. 7 is a magnetic property of a conventional magnetic disk medium. It is a sectional view showing the state of magnetic powder in a coating film. In the figure, 2..., 2a..., 2b... are magnetic powders, 4 is a substrate, 5...8 are first magnetic poles, 9.10 is a second magnetic pole, and 11.12 is a first magnetic pole. 3 magnetic pole, 13 nozzle, 1
4...17 are exciting coils, and 18...20 are magnetic fluxes, respectively. Applicant: Fujitsu Ltd. Agent: Minoru Aoyagi

Claims (1)

[Claims] A method for manufacturing a magnetic disk medium, comprising applying a magnetic paint made by kneading magnetic powder and a synthetic resin as a binder to a non-magnetic circular substrate to form a magnetic coating film on the surface of the substrate. , N and S pairs of magnetic poles are arranged on each surface of the substrate with a slight gap between them, and the N and S poles are parallel to each other, and the gap between the N and S poles is parallel to the substrate surface. These magnetic poles apply a horizontal magnetic field to the magnetic coating while applying the magnetic coating to the substrate.
After the magnetic coating film has dried somewhat, in addition to applying the above-mentioned horizontal magnetic field, a magnetic pole in the form of a two-part magnetic pole that is shaped to sandwich the remaining surface of the substrate is moved toward the substrate side, and the substrate is placed between the magnetic poles. A method of manufacturing a magnetic disk medium, which comprises applying a horizontal or perpendicular magnetic field to the remaining surface of the substrate while the substrates are being sandwiched.