JPH02189718A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the magnetic recording medium which is excellent in dimensional accuracy of the inside diameter, outside diameter, etc., and has excellent CSS durability by forming a magnetic recording layer on a substrate consisting of a synthetic resin and cutting the outer and inner peripheries thereof. CONSTITUTION:The magnetic recording layer is formed on the substrate consisting of the synthetic resin and the inner and outer peripheries thereof are cut. The cutting is executed by, for example, bringing a pair of cutting tool 21, 22 near to each other on the line running the center of rotation of the magnetic recording medium 10a while rotating the recording medium 10a, thereby simultaneously cutting the inner peripheral surface and outer peripheral surface of the recording medium 10a. The magnetic recording medium 10a which is excellent in the dimensional accuracy of the outside diameter, inside diameter, out of roundness, concentricity, etc., substantially obviates the generation of head crash, etc., and has high reliability is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a method of manufacturing a magnetic recording medium, and particularly to a method of manufacturing a magnetic recording medium using a substrate made of synthetic resin.

[Prior Art] Conventionally, in magnetic recording media, a magnetic recording layer made of Co, iron oxide, etc. is formed on a substrate made of an aluminum alloy whose surface is alumite-treated or metal-plated, and whose surface is mirror-polished. Magnetic recording media are known.

On the other hand, there has been a strong demand for weight reduction in recent years, and from this point of view, as described in JP-A-59-135133, a synthetic material that is lighter than aluminum alloy and has better workability has been proposed. Magnetic recording media using resin substrates have been attempted.

[Problems to be Solved by the Invention] However, in the invention described in JP-A-59-135133, when a substrate made of synthetic resin is molded by injection molding or the like, the high temperature molten synthetic resin is released into the mold. Although the synthetic resin is injected from the center of the cavity, the solidification rate of the synthetic resin at the periphery of the cavity is slow, and as a result, a deformed part is formed near the outer periphery of the injection molding surface due to shrinkage during solidification, and the outer periphery is raised. I finished it as a magnetic recording medium, installed it in a magnetic disk drive, used it, and started it.
There is a risk that the magnetic head will collide with the core during repeated stops, causing a head crash and damaging the magnetic recording layer. In other words, there is a problem that sufficient reliability regarding C3S durability cannot be obtained. Furthermore, when injecting and shaping molten synthetic resin into a mold, cooling it, or removing the molded product from the mold, it is extremely difficult to operate without leaving even the slightest distortion in the molded product. Yes, some distortion will remain.

Therefore, in order to finish the obtained substrate into a magnetic recording medium, when sputtering a magnetic material or applying a magnetic paint and curing it by heating, the heat applied to the substrate releases this residual distortion and heats the magnetic recording medium. Shrinkage etc. occur,
The problem is that the inner diameter is small, the outer diameter is large, and dimensional accuracy such as concentricity and roundness is impaired.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional technology and provide a magnetic recording medium with excellent dimensional accuracy such as inner diameter and outer diameter, and excellent C3S durability.

[Means for Solving the Problems] The gist of the present invention is to form a magnetic recording layer on a substrate made of synthetic resin, and then to cut the inner and outer peripheries.

Examples of the synthetic resin used in the present invention include, but are not limited to, polyetherimide, polyethersulfone, polyphenylene sulfide, polyarylate, polycarbonate, polyimide, and polyetherketone. Any synthetic resin with excellent properties may be used. Furthermore, inorganic fillers such as potassium titanate whiskers, carbon fibers, glass beads, ceramic powder, carbon, magenta, squid, etc. may be added to the synthetic resin as necessary. Note that the substrate made of synthetic resin may have a multilayer structure of two or more layers.

Further, in the present invention, the magnetic recording layer may be any magnetic layer such as a metal thin film magnetic layer made of Co or the like, or a coated magnetic layer made of magnetic powder (eg, iron oxide, iron carbide, etc.) and a synthetic resin binder.

The method for obtaining the substrate made of the synthetic resin of the present invention may be an injection molding method, a compression molding method, or a combination thereof, and is selected as appropriate.

Further, in the present invention, it is desirable that the inner diameter and outer diameter of the magnetic recording medium before cutting are smaller than a predetermined inner diameter of the magnetic recording medium and larger than the outer diameter. The difference from these predetermined dimensions becomes the cutting allowance, which will be described later.

Further, in the present invention, cutting is performed by simultaneously cutting the inner and outer peripheral surfaces of the magnetic recording medium by, for example, rotating the magnetic recording medium and moving a pair of cutting tools close to each other on a line passing through the center of rotation of the magnetic recording medium. do.

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 is a sectional view showing an example of a magnetic recording medium obtained by the method of manufacturing a magnetic recording medium of the present invention. In FIG. 1, the surface 12 of the magnetic recording layer of the magnetic recording medium 10 is flat with high precision over the entire surface because the bulges at the outer peripheral edge are not present due to cutting. The outer diameter and inner diameter d of the magnetic recording medium 10 are finished to predetermined dimensions with high precision by cylindrical vertical cutting surfaces 13 and 14 perpendicular to the magnetic recording layer surface 12. An inclined cutting surface 15 is formed between the outer circumferential edge of the magnetic recording layer surface 12 and the outer vertical cutting surface 13, and an inclined cutting surface 15 is formed between the outer circumferential edge of the magnetic recording layer surface 12 and the inner vertical cutting surface 13. Between surface 14,
An inclined cutting surface 16 is formed which is inclined with respect to both.

FIG. 2 is a cross-sectional view of the magnetic recording medium 10a at a pre-cutting stage in which a magnetic recording layer is formed on a substrate molded by injection molding or the like. As shown in FIGS. 3 and 4, the magnetic recording medium 10a is mounted on a rotating table 30 and rotated in the direction of the arrow while being fixed by means such as vacuum suction. During this rotation, the outer circumferential surface 11a and the inner circumferential surface 11b of the magnetic recording medium 10a are simultaneously cut by the cutting tools 21 and 22, respectively. The cutting blades 21a and 22a of the cutting tools 21 and 22 are the magnetic recording medium 1.
A vertical cutting surface 13.14 is formed which is perpendicular to 0a and as shown in FIG. The vertical cutting surfaces 13.14 allow the outer diameter Da of the magnetic recording medium 10a to
And the inner diameter da becomes the predetermined outer diameter and inner diameter d. The cutting blades 21a and 22a of the cutting tools 21 and 22 are arranged on a straight line A passing through the rotation center 0 of the magnetic recording medium 10a during cutting, and simultaneously move on this straight line A in a direction toward each other. Therefore, the forces from both cutting tools 21 and 22 due to cutting cancel each other out, and the force that attempts to horizontally move the magnetic recording medium 10a becomes zero or extremely small. Therefore, the turntable 30 rotates the magnetic recording medium 10a into the byte 21.
It is not necessary to suction and fix the magnetic recording medium 10a with strong force against the force from 22, and deformation of the magnetic recording medium 10a due to this fixing force can be prevented.

Furthermore, since the cutting blades 21a and 22a of the cutting tools 21 and 22 move along the straight line A, they ultimately cut the centers of the outer vertical cutting surface 13 and the inner vertical cutting surface 14 onto the magnetic recording medium 1.
They can be made to coincide with the rotation center O of 0a and to be concentric with each other. Therefore, even if the center of the magnetic recording medium 10a is slightly eccentric with respect to the rotation center 0, a highly accurate concentric magnetic recording medium can be obtained.

Then, as shown in FIG. 5, the other bytes 23.24
The outer peripheral edge and the inner peripheral edge of the magnetic recording medium 10a are cut using a cutting machine to form inclined cutting surfaces 15 and 16 as shown in FIG. The cutting tool 23.24 has recesses 23b, 24b, and the cutting blade 2 is inclined upwardly and downwardly in the recesses 23b, 24b.
3a and 24a. These cutting blades 23a, 24a
is arranged on a straight line passing through the rotation center O of the magnetic recording medium 10a (preferably the same as the straight line A, which is the movement locus of the cutting tool 21, 22, but may be different), and on this straight line move toward each other.

By cutting the inclined cutting surfaces 15 and 16,
The raised portion near the outer periphery is removed, and a magnetic recording medium with excellent flatness can be obtained. In addition, by cutting the vertical cutting surfaces 13 and 14, a magnetic recording medium having a predetermined outer diameter and inner diameter and excellent concentricity and roundness can be obtained.

In the present invention, the cutting method is not limited to the above explanation, and various embodiments are possible.

[Function] According to the method of the present invention, by cutting the outer and inner peripheries of a magnetic recording medium that has been heat-treated during the formation of the magnetic recording layer and has a large outer periphery and a small inner periphery, it is possible to reduce the swelling caused by the swelling near the outer periphery. The deformed portion can be removed, and the inner diameter, outer diameter, concentricity, and roundness can be highly precisely determined.

In addition, according to the method of the present invention, by bringing the pair of cutting tools close to each other on a line passing through the rotation center of the magnetic recording medium and simultaneously cutting the outer and inner peripheral edges of the magnetic recording medium, the forces from both cutting tools cancel each other out. Therefore, a weak force is sufficient to support the magnetic recording medium, and deformation of the magnetic recording medium due to this support can be prevented.

[Examples] Hereinafter, the present invention will be described in more detail based on Examples.

Using polyetherimide resin, substrates having a thickness of 1.9 mm and two types of outer and inner diameters as shown in Table 1 were molded by injection molding, and then 7-Fez0 was molded onto these substrates. A magnetic paint containing = as a magnetic material was applied by a spin code method, and further heated at 200°C for 2 hours to harden the magnetic layer.

Table 1 (Unit: 2μ) Next, the outer and inner circumferences of the No. 2 sample were simultaneously cut using a cutting device such as that shown in Figures 4 and 5, and the vertical cutting surface and the inclined A magnetic recording medium was obtained by forming a cut surface.

Nα1. Nα2 magnetic recording medium outer diameter, inner diameter, roundness,
Concentricity was measured using a three-dimensional measuring machine and the results were shown in the table.
Shown in 2.

Table 2 (Unit: μ) As is clear from Table 2, the ones that have been subjected to cutting processing are
The outer diameter, inner diameter, roundness, and concentricity were all highly accurate, making it suitable for practical use.

[Effect] As described above, according to the present invention, by forming a magnetic recording layer on a substrate made of synthetic resin and then cutting it, dimensional accuracy such as outer diameter, inner diameter, roundness, and concentricity can be improved. Excellent,
Furthermore, it is possible to obtain a highly reliable magnetic recording medium in which head crashes and the like hardly occur.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an example of a magnetic recording medium obtained by the method of manufacturing a magnetic recording medium of the present invention, FIG. 2 is a cross-sectional view of the magnetic recording medium before cutting, and FIG. 3 is a cross-sectional view of the magnetic recording medium before cutting. FIG. 4 is a plan view illustrating the machining process, FIG. 4 is a sectional view thereof, and FIG. 5 is a sectional view illustrating the second stage cutting process. 10--Magnetic recording medium, 13.14--Vertical cutting surfaces on outer and inner circumferences 15.1
6- Sloped cutting surfaces 21 to 24 on the outer and inner peripheries -- Hyde Figure 1

Claims (1)

[Claims] (1) Forming a magnetic recording layer on a substrate made of synthetic resin,
1. A method of manufacturing a magnetic recording medium, characterized in that the outer periphery and the inner periphery are then cut.