JPH02278514A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To hold a lubricant on a medium for a long time by providing one or more grooves having square cross section on the surface of a substrate in a manner that the grooves are concentrical with the medium and forming a recording layer on the surface having these grooves. CONSTITUTION:A disk substrate 1 made of polyether imide is produced by injection molding with a specific die. The die has projections with a square cross section which are concentrically provided with specified intervals, and other area except for said projections has a concentrical fine rugged pattern. On the obtd. substrate, a Cr base layer 2, Co-Ni-Cr magnetic layer 3 (Co:Ni:Cr = 75:15:10) and C protective layer 4 are successively formed by DC magnetron sputtering. Then a fluororesin lubricant 5, 8 is applied on the protective layer 4 by spray coating and made to fill the grooves 7 by use of a tape polishing device. The groove 7 has 0.3 - 1mum width and depth. By this method, such a medium having excellent holding effect of lubricant and free from adsorption of a disk head slider can be manufactured at low cost.

Description

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

[Prior Art] A conventional magnetic recording medium will be explained using a magnetic disk as an example.

Conventionally, as a magnetic disk, an alumite aluminum alloy is used as a substrate, and grooves are formed on the surface of this substrate using an abrasive material such as sandpaper. Japanese Patent Laid-Open Publication No. 123906/1983 discloses a technology. .

By forming a recording layer on a substrate on which grooves have been formed, grooves can also be formed in the recording layer.

According to such a magnetic disk, by forming grooves in the recording layer, it is possible to prevent the magnetic head from adhering to the surface of the magnetic disk, and therefore, damage to the recording layer can be prevented.

On the other hand, conventionally, in order to improve the CCS characteristics of a magnetic disk and increase the reliability of the magnetic disk, a lubricant has been applied onto the disk substrate. In particular, in magnetic recording media whose recording layer is a metal thin film formed by sputtering or the like, lubricants that are liquid at room temperature are mainly used because of their good flowability.

[Problems to be Solved by the Invention] However, when a lubricant is applied to the magnetic disk as described above, the following problems occur.

When a lubricant is applied to a magnetic disk having grooves on its surface, the lubricant fills the grooves. This itself is preferable in terms of preventing the lubricant from scattering and disappearing. In other words, for magnetic disks that do not have grooves formed on their surface,
With long-term use, the lubricant tends to scatter and disappear, and if more lubricant than necessary is applied to prevent the lubricant from disappearing, the head tends to stick when the disk stops. On the other hand, when grooves are provided on the surface of the magnetic disk and the grooves are filled with lubricant, the lubricant becomes extremely difficult to scatter and disappear.

If the substrate is made of resin, the lubricant can be supplied to parts of the surface of the magnetic disk other than the grooves in a timely manner by elastic deformation of the grooves when the magnetic disk and the helad slider come into contact with each other.

However, since the grooves of the conventional magnetic disk were formed using an abrasive material, grooves 7 having a substantially inverted triangular cross-sectional shape were formed as shown in FIG. 2(a). Therefore, even if the magnetic disk is slightly curved, the groove width will be pinched due to elastic deformation and the groove volume will be reduced. A portion of the lubricant flows out of the groove, and when the magnetic disk is used, the lubricant becomes in a state as shown in FIG. 2(c). Therefore, the effect of preventing the lubricant from scattering and flowing out is weakened, and more lubricant than necessary is supplied to areas other than the grooves.

SUMMARY OF THE INVENTION An object of the present invention is to solve these conventional problems and provide a magnetic recording medium that has excellent long-term lubricant retention ability and that does not cause adhesion between the magnetic recording medium and the Herad slider.

[Means for Solving the Problems] The gist of the present invention is a magnetic recording medium having at least a base formed of a resin and a recording layer formed of a magnetic material, the surface of the base having a rectangular cross-sectional shape. A magnetic recording medium is characterized in that one or more grooves are provided concentrically, and the recording layer is formed on the surface of the substrate where the grooves are provided.

(Magnetic Disk Substrate) The magnetic disk substrate used in the present invention is made of resin such as acrylic, polycarbonate, polyimide, or epoxy, and may contain an inorganic filler such as glass fiber or alumina particles.

Grooves as shown in FIG. 1 are provided on the surface of this resin magnetic disk substrate. For resin magnetic disk substrates, injection molding,
Since a molding method such as compression molding is used, mass production is easily possible by processing the mold at this time.

(Groove) The cross-sectional dimensions of the groove are set to a groove width of 0 in order to efficiently retain the lubricant and not adversely affect the magnetic disk recording performance.
．． 3μm or more and 1μm or less, groove depth 0.3μm or more and 1μm
The following is desirable. If the groove width is 0.3 μm or less, it is difficult to fill the groove with the lubricant when applying the lubricant, and if it is 1 μm or more, it will lead to a decrease in the reproduced signal, which is not preferable. The depth of the groove is 0.3μm
In the following cases, it is difficult to retain the lubricant necessary for long-term use (for example, C 5.55 million times). Due to deformation, it cannot flow out of the groove.

Further, in order not to affect the seek of the head, the interval between the grooves is preferably narrower than the width of the head slider ski portion, and most preferably about one third of the width of the head slider ski portion.

The cross-sectional shape of the groove is preferably rectangular or trapezoidal, and most preferably trapezoidal in shape, with the lower side being longer than the upper side in order to increase the amount of lubricant retained without increasing the groove width. Since the magnetic recording medium of the present invention uses a resin base,
It becomes possible to easily form a groove having such a shape.

Furthermore, by applying texturing treatment to portions other than the groove portions, it is possible to produce a magnetic recording medium that has better friction resistance and is less likely to attract the head.

[Function] According to the present invention, since grooves having a square cross-sectional shape are provided on the surface of the base of the magnetic recording medium, the volume of the grooves does not become extremely small even if the magnetic recording medium is slightly curved. Therefore, although a small amount of lubricant may flow out, most of the lubricant can be retained in the groove.

Further, according to the present invention, since resin is used as the base of the magnetic recording medium, it is possible to provide a magnetic recording medium having grooves having a rectangular or trapezoidal cross section with good mass productivity.

[Example] (Example 1) As an example of the present invention, a magnetic disk having grooves with a substantially square cross section as shown in FIG.
An S test was conducted. In FIG. 1, 1 is a resin magnetic disk substrate, 2 is a Cr underlayer, 3 is a magnetic layer, 4 is a protective layer, and 5 is a lubricant.

First, a method of manufacturing the magnetic disk of this embodiment will be explained.

■ Concentric protrusions with a square cross-sectional shape of 0.5 μm in height and 0.5 μm in width are provided at intervals of 200 μm, and fine circumferential irregularities with an average radial roughness of 8 nm are provided in areas other than 6. A magnetic disk substrate made of polyetherimide was produced by injection molding using the mold.

■On this magnetic disk substrate, a 200 nm Cr underlayer,
Co-Ni-Cr magnetic layer (Co:Ni:Cr=75:1
5:10) A 80 nm thick C protective layer and a 30 nm thick C protective layer were sequentially formed using a D, C and magnetron type sputtering device.

(2) A fluororesin lubricant was applied to the surface of the protective layer by a spray method, and then a tape polisher was used to fill the grooves with the lubricant and remove excess lubricant.

A CSS test was conducted on the magnetic disk medium of this example obtained through the above steps, and an increase in the coefficient of dynamic friction was measured. The results are shown in Table 1. For comparison, evaluation results of a conventional magnetic disk medium in which the above-mentioned underlayer, magnetic layer, and protective layer were provided on a resin magnetic disk substrate that did not use the present invention and were subjected to lubrication treatment are also listed. For the C3S test, a 3370 type mini monolithic head with a track width of 24 μm and a load of 9.5 g was used.

As can be seen from Table 1, in the magnetic disk of this example, there was almost no increase in the coefficient of dynamic friction.

Table 1 (Example 2) The same magnetic disk as in Example 1 was prepared, and after being left for 60 hours, the increase in the coefficient of static friction was measured. The results are shown in Table 2. For comparison, evaluation results of a conventional magnetic disk medium in which the above-mentioned underlayer, protective layer, and lubrication treatment were provided on a resin magnetic disk substrate that does not use the present invention are also listed. A 3370 mini monolithic type head with a track width of 24 μm and a load of 9.5 g was used for the CSS test.

As can be seen from Table 2, in the magnetic disk of this example, there was almost no increase in the coefficient of static friction. 6. Magnetic disk. 7. Groove.

Table 2

Claims (5)

[Claims] (1) A magnetic recording medium having at least a base made of resin and a recording layer made of a magnetic material, in which one or more concentric grooves with a square cross section are provided on the surface of the base. , and the recording layer is formed on the surface of the substrate where the groove is provided. (2) The magnetic recording medium according to claim 1, wherein the groove has a trapezoidal cross-sectional shape. (3) The groove width is 0.3 μm or more and 1 μm or less, and the groove depth is 0.3 μm or more and 1 μm or less.
Claim 1 characterized in that the diameter is 3 μm or more and 1 μm or less.
Or the magnetic recording medium according to 2. (4) The magnetic recording medium according to any one of claims 1 to 3, wherein the groove interval is less than or equal to the width of the head slider key portion. (5) The magnetic recording medium according to any one of claims 1 to 4, characterized in that a texturing process is applied to portions other than the grooves.