JPS62231427A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent the starvation of a lubricating agent and to remarkably improve the durability of a magnetic recording medium so as to prevent the deterioration in the durability by the worn powder of a recording and reproducing head and the magnetic recording medium by successively forming a magnetic layer and protective layer on a nonmagnetic substrate, forming many concentrical circular grooves on the surface of the protective layer and forming a lubricating layer thereon. CONSTITUTION:The many concentrical circular grooves 3a are formed on the surface of the protective layer 3. The grooves are formed to <=0.02mum, more preferably <=0.015mum depth. A fluorocarbon lubricating agent is adequate as the lubricating material to be used for a lubricating layer 4. The lubricating layer 4 is usually coated as thinly about 0.003-0.005mum. The magnetic recording medium constituted in such a manner has the improved durability as the lubricating layer stored in the concentrical circular grooves on the protective layer is gradually replenished to the surface. Furthermore, the worn powder generated by a durability test, etc., is expelled into the groove parts and therefore, the acceleration of the wear by the worn powder itself is prevented and the drop-out, etc., are prevented. The recording and reproducing characteristics are improved as well.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a magnetic recording medium with excellent durability.

(Prior Art) In recent years, as the demand for high-density recording has increased, there has been a strong demand for the practical use of perpendicular magnetic recording media that are essentially capable of high-density recording.

For such perpendicular magnetic recording media, a Co-0r thin film is formed by batch or continuous sputtering on the surface of a nonmagnetic support made of a heat-resistant polymer film such as polyimide or polyethylene terephthalate. are being tested as being particularly suitable for floppy disks.

However, in high-density magnetic recording media using such magnetic thin films, it is not possible to include a lubricating material in the magnetic recording layer along with magnetic powder and binder, as is the case with conventional coating-type media. In order to bring the recording and reproducing head closer to each other, the surface of the recording and reproducing head is also smoothed, resulting in extremely large dynamic friction with the recording and reproducing head, resulting in a problem that sufficient durability cannot be ensured.

(Problem to be Solved by the Invention) For this reason, it has been conventionally considered to apply a liquid lubricant to the surface of a magnetic recording medium to form an n-slip layer to reduce the coefficient of dynamic friction between the magnetic recording medium and the recording/reproducing head. ing.

However, if the lubricant is applied thickly, this lubricant becomes a spacing between the magnetic recording medium and the recording/reproducing head, lowering the output signal level, and if the recording/reproducing head is running on the same track, the lubricant becomes a spacing between the magnetic recording medium and the recording/reproducing head. There is a problem in that the output signal becomes large due to the exclusion, and the output signal level becomes unstable.

In addition, if the thickness of the RA lubricant is reduced to avoid such problems, the lubricant will be depleted in the middle of the term due to natural reduction or adsorption to wear particles, and the r! ! There is a problem in that the friction increases and eventually uneven scratches occur on the surface of the magnetic recording medium.

As a solution to such problems, Japanese Patent Application Laid-Open No. 59-1124
No. 32 discloses a method of forming irregularities on the surface of a magnetic layer and interposing a lubricant in the recesses.

However, since these irregularities are formed by depositing a substance different from that of the magnetic layer on the surface of the magnetic layer, they are similar to the irregularities that occur on the surface of the magnetic layer, and the effect of improving durability is still insufficient. Furthermore, even if larger irregularities are formed, lubricant tends to accumulate in the recording/reproducing head portion when the floppy disk or the like stops rotating, which may even cause trouble.

゛ (Objective) The present invention has been made to solve these conventional difficulties, and is to provide a stable and low dynamic a! The object of the present invention is to provide a magnetic recording medium that has a friction coefficient and thereby achieves high durability.

(Means for Solving the Problems) In order to solve the above object, the present invention provides a magnetic recording medium in which a magnetic layer, a protective layer and a lubricating layer are sequentially provided on a non-magnetic support. It is characterized by having a large number of concentric grooves formed on it.

Non-magnetic supports used in the present invention include flexible polymer films such as polyester films and polyimide films, glass, ceramics, non-magnetic metals,
Examples include hard disks made of metal oxide.

Further, as the magnetic material used for forming the magnetic thin film of the present invention, iron, cobalt, nickel, other ferromagnetic metals, or alloys thereof, such as l"e-Go, l"e
-Ni, co-Ni, and furthermore, for example, Mn, 7-n, 3i, Cu, Cr,
R11.

Among these, Co-based alloys are particularly suitable for the present invention, including those to which one or more elements such as Re, P, YlVlB, W, and Ss are added.

A magnetic thin film is formed by depositing these ferromagnetic materials onto a nonmagnetic support directly or through another underlayer by a method such as vacuum evaporation, ion plating, or sputtering. The thickness of this magnetic layer is suitably in the range of 0.1 to 1.0 μm.

Further, as the material used for the protective layer formed on the magnetic layer, a material having a harder hardness than the constituent material of the magnetic layer, such as Al2O2, SiO2, Si3N4, etc., is suitable. The thickness of this protective layer is usually about 0.01 to 0.03 μm. In general, if the thickness of the protective layer is too thick, spacing loss will occur, but if the distance between the magnetic recording medium and the recording/reproducing head is determined by the flying height during normal operation, the thickness may be reduced to 0. The thickness can be reduced to about .05 μm. This protective layer is formed by a method such as vacuum evaporation, ion plating, or sputtering, like the magnetic layer.

The pitch, continuity, or discontinuity of the concentric grooves formed on the surface of the protective layer can be set arbitrarily, but if the depth of the grooves exceeds 0.02 μm, the lubricant will become localized and the output signal will be affected. The thickness is preferably 0.02 μm or less, preferably 0.015 μm or less, since the level may become unstable or the magnetic layer may be exposed, which may reduce durability. If the grooves are shallow, the amount of lubricant stored here will be small, but in this case, the density of the lubricant stored can be adjusted by adjusting the density of the grooves formed.

Ho 11i! ! It is possible that the output signal level decreases due to the presence of the grooves on i, but in reality there are around 50 irregularities on the surface of the magnetic layer, and the groove width is also 1 μm.
, so there is almost no decrease in output.

Furthermore, even if the grooves are interrupted at some places due to the presence of such unevenness on the surface of the magnetic layer, the effect of the present invention is not significantly affected.

Note that this groove can be formed, for example, by pressing a #8000 tape onto the protective layer with an appropriate pressing force while rotating the magnetic recording medium at high speed, and slowly moving the tape from the inner circumference toward the outer circumference.

Furthermore, as a lubricant to be used in the lubricating layer, 70 fluorocarbon-based R8 lubricant is suitable, and commercially available products include Talitex (manufactured by DuPont, trade name of fluorocarbon-based lubricating oil), Fontprin (Monte Floss). Company-made, 70
(trade name of carbon-based lubricating oil), etc. This lubricating layer is usually applied as thin as 0.003 to 0.000 μm.

The drawing shows a cross section of the magnetic recording medium of the present invention configured as described above, in which a magnetic layer 2 is formed on the surface of a non-magnetic support 1, a protective layer 3 is formed on this magnetic layer 2, There are many concentric circles on this 8m2 surface? 113 a is formed, and a lubricating layer Fm4 is formed on the surface of this protective layer 3.

(Function) The magnetic recording medium configured in this way has a high retention rate. ! Lubricant is stored in the concentric grooves on the layer and gradually replenished to the surface, improving durability.Furthermore, wear particles generated during durability tests are removed into the grooves, so the wear particles themselves are removed. Acceleration of wear is prevented, dropouts and the like are prevented, and recording/reproducing characteristics are improved.

Also, when applied to floppy disks, surplus rR
Since the lubricant is stored in the groove, the lubricant will not move and accumulate under the recording/reproducing head even if the drive is stopped.

(Example) Next, examples of the present invention will be described.

Example 7 A Co-0r alloy was deposited to a thickness of 0.4 μm on both sides of a 5 μl thick polyimide film by sputtering.

Next, a 3.5-inch floppy disk was punched out, and the surface was coated with Si to a thickness of 0.02 μm by sputtering.
02 protection! ! formed a layer.

Next, while rotating the magnetic recording medium at high speed, 98 cm was applied onto the protective layer.
By pressing the 000 tape with an appropriate pressure and moving it slowly from the inner circumference to the outer circumference, a large number of grooves with a depth and width of 0.01 μm or less can be maintained! [Formed on the surface.]

Next, the surface of this Mm was coated with Talitex to a thickness of o, oosμ- by a spin-coating method to produce 10 floppy disks.

When this floppy disk was subjected to a durability test and the time change of prerecorded signals was examined, almost no decrease in output was observed in all of the floppy disks of this example even after 10 million buses. On the other hand, in comparison example floppy disks manufactured under the same conditions as the example except that many grooves were not formed in the protective layer, the output signal level decreased by 70% in 2 out of 10 disks before 6 million buses. I saw something. Furthermore, when the Otsubee disc of the example was observed using a scanning electron microscope, it was clear that there were many particles that appeared to be wear particles especially in the grooves, but in the comparative example, they were not dispersed on the surface. It was attached.

Furthermore, with the floppy disk of the example, even after 10 million passes! Although sufficient lubricant remained in the lubricant, in the comparative example, the lubricant was depleted after 6 million baths.

In the above embodiments, an example in which the present invention was applied to a floppy disk was explained, but even when the present invention was applied to a hard disk whose substrate was made of metal or the like, improvement in durability was observed.

[Effects of the Invention] As explained above, in the present invention, a magnetic layer and a protective layer are sequentially formed on a non-magnetic support, and a large number of concentric grooves are formed on the surface of the protective layer. Since the i11 lubricating layer is formed on the magnetic recording medium, deterioration in durability due to depletion of lubricant and abrasion particles between the recording/reproducing head and the magnetic recording medium can be significantly improved.

[Brief explanation of drawings]

The drawings are partial cross-sectional views illustrating details of the invention.

Claims (5)

[Claims] (1) A magnetic recording medium comprising a magnetic layer, a protective layer and a lubricating layer provided in this order on a non-magnetic support, characterized in that a large number of concentric grooves are formed on the surface of the protective layer. magnetic recording medium. (2) The magnetic recording medium according to claim 1, wherein the depth of the concentric grooves is 0.02 μm or less. (3) The magnetic recording medium according to claim 1 or 2, wherein the magnetic layer is made of a Co alloy. (4) The magnetic recording medium according to any one of claims 1 to 3, wherein the lubricant layer is made of a fluorocarbon-based lubricant. (5) The magnetic recording medium according to any one of claims 1 to 4, wherein the magnetic layer is formed by vacuum deposition, ion plating, or sputtering.