JPH0513331B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention and Purpose of the Invention] The present invention relates to improving the protective lubricant layer of a magnetic recording medium, and aims to provide a magnetic recording medium with excellent running properties and wear resistance, and a method for manufacturing the same. do. [Prior Art] Metal thin film magnetic recording media such as Co--Ni or Co--Cr have attracted attention as high-density recording media, and their excellent high-density recording performance has been demonstrated. However, when compared with coated magnetic recording media, the running properties and wear resistance of metal thin film magnetic recording media are still far from satisfactory. Therefore, the above 2
Various protective lubricant layers have been studied to improve the two mechanical properties, but it has been extremely difficult to significantly improve the two problems mentioned above at the same time. for example,
When using a fluorocarbon-based liquid lubricant, which is the most common lubricant for magnetic recording media, it is possible to significantly reduce the friction coefficient and improve the running properties of the recording media, but it is not sufficient in terms of wear resistance. No results are obtained. In addition, in the case of the vapor-deposited film of fatty acid metal salt disclosed in JP-A-54-113303, although the abrasion resistance of the recording medium can be improved, the relatively large coefficient of friction makes it difficult to maintain sufficiently good running characteristics. cannot be obtained. [Means for Solving the Problems] The present invention solves the above-mentioned drawbacks of the prior art, by providing an adsorption layer of a fatty acid metal salt with excellent wear resistance on a magnetic recording surface, and forming an adsorption layer on the adsorption layer. By providing a fluorocarbon-based liquid lubricant layer that exhibits a low coefficient of friction, the wear resistance is improved while maintaining a low friction state. The fatty acid metal salts referred to in the present invention are metal salts of high molecular weight linear fatty acids, particularly Li salts, K salts, and Na salts of fatty acids such as lauric acid, myristic acid, palmitic acid, oleic acid, and stearic acid. , Ba
Fatty acid metal salts such as salt, Ca salt, Zn salt, and Pb salt are effective. The optimum film thickness of this fatty acid metal salt is in the range of 40 Å to 1000 Å. If it is less than 40 Å, the fatty acid metal salt molecules will not completely cover the magnetic recording surface, and no significant improvement in the wear resistance of the magnetic recording medium will be observed. I can't do it.
Further, if the film thickness exceeds 1000 Å, the distance between the magnetic head and the surface of the recording magnetic layer becomes large, which is undesirable from the viewpoint of recording and reproducing characteristics because spacing loss becomes large. In addition, perfluoroalkyl polyether is effective as a fluorocarbon liquid lubricant provided on the fatty acid metal salt adsorption layer, and the optimal film thickness is
It ranges from 100 Å to 3000 Å. When the thickness is less than 100 Å, the surface of the fatty acid metal salt adsorption layer cannot be completely covered, and when it exceeds 3000 Å, adhesion occurs between the magnetic head and the recording medium, resulting in poor running. As mentioned above, by combining a fatty acid metal salt adsorption layer and a fluorocarbon-based lubricant layer as a surface protective lubricant layer for a magnetic recording medium, it is possible to improve the running properties of the magnetic head and improve the wear resistance of the magnetic recording medium. We were able to improve it significantly. [Example] Hereinafter, the present invention will be described with reference to the drawings. Example 1 A Co-Ni film 2 obliquely deposited on a polyethylene terephthalate film 1 with a thickness of 12 μm at an incident angle of 20° to 70° was used as a sample, and the film thickness was
200Å sodium oleate vapor deposited film or fluorocarbon liquid lubricant layer, or 200Å film thickness
The service life and friction coefficient of the recording medium were evaluated for each case in which the fluorocarbon liquid lubricant layer 4 was provided on the sodium oleate vapor-deposited film 3. The usable life of the recording medium was evaluated by still playback life by a still test, and the friction coefficient was measured using a spherical sliding tester. The fluorocarbon liquid lubricant used in this example was Krytox.
The product name of Dupou is used, and the film thickness is approximately 0.1 μm. The molecular structure of Krytox is as follows. molecular structure formula The evaluation results of the above samples are summarized in Table 1 below.

[Table] From this table, it can be seen that by providing a vapor-deposited film of sodium oleate on the surface of a recording medium, the wear resistance of the recording medium is improved and the still playback life is also improved compared to a non-lubricated case, but the coefficient of friction is significantly reduced. It turns out that no significant improvement can be expected. On the other hand, in the case of a recording medium coated with only Krytox, although the friction coefficient is greatly improved, the still playback life is not significantly improved. However, on the vapor deposited film of sodium oleate,
It can be seen that providing a lubricating layer of Krytox greatly improves both the still play life and the coefficient of friction. Example 2 Formed on a glass substrate with a diameter of 75 mm and a plate thickness of 3 mm.
A Co-Cr sputtering disk was used as a sample, and after providing an adsorption layer of lithium stearate with a film thickness of approximately 90 Å on the surface of the sample, a fluorocarbon-based lubricant was applied.
FomblinZ (product name of Monteflores) was applied. The molecular structural formula of FomblinZ is as follows. Molecular structural formula: CF ₃ [(OCF ₂ CF ₂ ) m - (OCF ₂ ) n] OCF ₃ The wear resistance and friction coefficient of the above magnetic disk were measured using a saphire slider with a curvature of 30 mm and a circumferential speed of 2 m/min. A spherical sliding test was conducted and evaluated, with the pressing load of the spherical slider against the second magnetic disk being 6 g.
The test results are summarized in Table 2.

〔Effect of the invention〕

As explained above, by providing an adsorption layer of a fatty acid metal salt on the magnetic recording surface of a magnetic recording medium and further providing a fluorocarbon-based liquid lubricant layer on the adsorption layer, good compatibility with the adsorption layer can be achieved. It can maintain an extremely low friction state and has extremely high spherical sliding strength compared to fluorocarbon solid lubricant layers.
The running properties and wear resistance of magnetic recording media can be significantly improved.

[Brief explanation of the drawing]

The figure is a cross-sectional view of a magnetic recording medium according to an embodiment of the present invention. 1... Polyethylene terephthalate film,
2... Co-Ni film, 3... Sodium oleate vapor deposited film, 4... Lubricating layer.

Claims (1)

[Scope of Claims] 1. A magnetic recording medium characterized in that a fatty acid metal salt adsorption layer is provided on a magnetic recording surface, and a fluorocarbon liquid lubricant layer is provided on the layer. 2. A method for producing a magnetic recording medium, which comprises providing an adsorption layer of a fatty acid metal salt on a magnetic recording surface by vacuum deposition, and then applying a fluorocarbon-based liquid lubricant onto the adsorption layer.