JPH01285018A - magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the magnetic recording medium having excellent corrosion resistance and wear resistance and high reliability by providing an org. protective film mixed with a fluorine graft polymer and carbon fluoride lubricating agent on an inorg. protective film. CONSTITUTION:A Cr film or Cr alloy film 4 is formed by a sputtering method on a magnetic metallic film 3 and the org. protective film 6 mixed with the fluorine graft polymer and the carbon fluoride lubricating agent is coated thereon. Namely, some degree of the corrosion resistance is assured by the Cr film or Cr alloy film 4 and the fluorine graft polymer covers the defective part of the Cr film or Cr alloy film 4 even if said film is damaged and the defective part is generated thereon. The excellent corrosion resistance is thus assured by the Cr film and the fluorine graft polymer and the excellent wear resistance is assured by the fluorine lubricating agent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic storage device, such as a magnetic recording medium used in a magnetic disk device.

BACKGROUND OF THE INVENTION At present, most of the magnetic disks used as magnetic recording media are oxide-coated media, and there are thin metal film media formed by plating or sputtering to further improve the recording density.

However, metal thin film media do not have sufficient corrosion resistance (,
The wear resistance due to contact with the magnetic head during contact start/stop (C8S) is also insufficient. Therefore,
Generally, in metal thin film media, a protective film and a lubricating film are formed on the metal magnetic film in order to impart corrosion resistance and wear resistance. Furthermore, in order to increase the recording density, it is preferable that the magnetic head be as close as possible to the surface of the metal magnetic film, so the thinner the protective film or lubricant film is, the better.

Conventionally, a metal thin film (Rh.

Au, Cr, N1-P, etc.) oxide film (surface oxidation of metal magnetic film, 5i02, etc.), nitride film (Si3-N4, etc.)
Hard films such as carbide films (SiC) have been proposed.

Problems to be Solved by the Invention Among these protective films, there are some that have considerably excellent corrosion resistance and wear resistance. However, although the above conventional protective films can ensure a certain degree of corrosion resistance,
The thinner the film, the more likely it is that the film will corrode. This is due to damage to the protective film caused by the process of removing protrusions or sudden collision between the magnetic head and the magnetic recording medium. It is known that defects occur in the protective film, leading to corrosion.Furthermore, it is difficult to eradicate dust before and after film formation, which causes protrusions. Corrosion prevention solely by means of corrosion protection is considered to be difficult.

Furthermore, a fluorocarbon-based liquid or solid lubricant is generally applied to the surface of the magnetic recording medium.

This is aimed at improving the low friction and wear resistance of the magnetic recording medium, and therefore has little effect on corrosion resistance.

Furthermore, although fluorine-based graft polymers are quite effective in terms of corrosion resistance, they are very problematic in terms of wear resistance. In other words, there is currently no organic protective film that can fully improve both corrosion resistance and wear resistance.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention coats a metal magnetic crotch with a Cr film or a Cr alloy film by sputtering, and coats a fluorine-based graft polymer and a fluorocarbon-based film thereon. Cover with an organic protective film mixed with lubricant.

Effect of the present invention With the above-described configuration, the Cr film or Cr alloy film formed by sputtering on the metal magnetic film has a certain degree of corrosion resistance, and even if the Cr film or Cr alloy film is formed by a protrusion removal process or the like, the Cr film or Cr alloy film is Even if the alloy film is damaged and defects occur, extremely excellent corrosion resistance can be obtained by covering the defects with the fluorine-based graft polymer. Since the Cr film or Cr alloy film ensures a certain degree of corrosion resistance, fluorine-based graft polymers can be used to cover defective areas (corrosion resistance can be satisfied with only a small amount. The disadvantage of wear resistance can be compensated for by mixing it with a fluorocarbon lubricant.In other words, the Cr film and fluorine graft polymer ensure excellent corrosion resistance.
Fluorocarbon lubricants ensure excellent wear resistance.

Needless to say, in order to ensure excellent corrosion resistance only with a fluorine-based graft polymer without forming a Cr film or Cr alloy film, a large amount of fluorine-based graft polymer is required, which significantly deteriorates wear resistance. . Also,
In order to ensure excellent corrosion resistance with only a Cr film or Cr alloy film, the film must be thick, and high recording density cannot be expected. Defects occur and excellent corrosion resistance cannot be ensured.

Embodiment FIG. 1 shows an embodiment in which the present invention is applied to a magnetic disk, and the present invention will be explained in detail using this embodiment.

[1] As shown in the example diagram, for example, Ni-P with a thickness of 20 um is deposited on a disk substrate 1 made of an aluminum alloy or the like.
An electroless plating base film 2 is formed on which, for example,
Co-Ni alloy, Co-Cr alloy, Co with Cr base
- A metal magnetic film 3 such as a Ni-Cr alloy is formed, and then a Cr film or a Cr alloy film 4 is formed with a thickness of 00 angstroms, and a carbon film 5 is further formed with a thickness of 200 angstroms. Formed with a film thickness of
Furthermore, a magnetic disk was prepared in which an organic protective film 6 made of a mixture of a fluorine-based graft polymer and a fluorocarbon-based lubricant was formed with a film thickness of several angstroms to several tens of angstroms.

In addition, polyacrylic acid ester-(CHCH2)n is used as a fluorine-based graft polymer that is a material for the organic protective film.
- COOC)12CH2C7F15 Alternatively, polymethacrylic acid ester CH3 -(CCH2)n- CO0CH2CH2C7F15 Alternatively, a mixture of these can be used.

[2] Comparative Example 1 A magnetic disk was produced in the same manner as in the example except that the organic protective film 6 was made of only a fluorocarbon lubricant.

[31 Comparative Example 2 A magnetic disk was prepared in the same manner as in the example except that the organic protection @6 was made of only a fluorine-based graft polymer.

141 Comparative Example 3 Same as Example, except that t with Cr film, X4i, C
A magnetic disk without the r-alloy film 4 was created.

Next, using the magnetic disks shown in Examples and Comparative Examples 1.2.3, magnetic heads and disks were subjected to a repeated start/stop test (C3S test) and a corrosion resistance test at a temperature of 80°C and a relative humidity of 80% for 500 hours. carried out. In the C3S test, the magnetic disk of the example showed no scratches after 20,000 cycles of C8S, and there was almost no increase in the coefficient of friction, and in the corrosion resistance test, no corrosion occurred at all, showing an extremely low It exhibited friction, wear resistance, and corrosion resistance. On the other hand, in Comparative Example 1, C8
In the S test, the results were similar to those in the example, but in the corrosion resistance test, corrosion occurred at several locations on the magnetic disk surface. Furthermore, in Comparative Example 2, scratches occurred after 1000 cycles in the C8S test. In Comparative Example 3, a large amount of corrosion occurred in the corrosion resistance test.

The results of the above test are shown in Table 1.

Here, we have described the case where a mixed film of a fluorine-based graft polymer and a fluorocarbon-based lubricant is coated on a Cr film or a Cr alloy film. It may be a protective film (,
Moreover, it can be easily inferred that even if another film such as a carbon film is present between the inorganic protective film and the mixed film, the same effect will be obtained.

Effects of the Invention According to the present invention, a magnetic recording medium with extremely excellent corrosion resistance and wear resistance and high reliability can be obtained. Further, since the above characteristics can be obtained with a very thin film, the magnetic head can be brought closer to the metal magnetic film, and the present invention can realize high recording density.

Table 1

[Brief explanation of the drawing]

The figure is a sectional view of a magnetic disk in one embodiment of the present invention. 1... Aluminum substrate for disk 2... N1-P electroless base film 3... Metal magnetic film 4... Cr alloy film 5... Carbon film 6... Organic Protective film (mixed film of fluorine-based graft polymer and fluorocarbon-based lubricant)

Claims (2)

[Claims] (1) A magnetic recording medium comprising an inorganic protective film formed on a metal magnetic thin film, and an organic protective film containing a mixture of a fluorine-based graft polymer and a fluorocarbon-based lubricant thereon. (2) The fluorine-based graft polymer is a polyacrylic ester ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Or polymethacrylic ester ▲There are mathematical formulas, chemical formulas, tables, etc.▼ The magnetic recording medium according to scope 1.