JPH0640386B2 - Surface lubrication method for magnetic recording media - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a surface lubrication method for improving the wear resistance of a magnetic recording medium.

[Prior art]

In a storage device such as a magnetic tape device or a floppy disk device that uses a magnetic recording medium having a magnetic film formed on a flexible substrate, the magnetic head and the magnetic recording medium are in contact with each other when recording and reproducing a signal.

On the other hand, in a magnetic disk device using a magnetic recording medium in which a magnetic film is formed on a rigid substrate such as aluminum,
When a floating head slider, which is a dynamic pressure gas bearing, is used to float a magnetic head on a recording medium that rotates at high speed up to a minute clearance, and recording / reproducing signals in a non-contact state, the surface of the recording medium is rough. When the floating clearance of the magnetic head is reduced due to disturbance such as dust or dust, contact between the magnetic head and the recording medium occurs.

Further, in recent years, a contact start stop (CCS) type magnetic disk device for starting and stopping a drive motor for rotating the recording medium in a state where the magnetic head is stationary on the recording medium has become mainstream. In this case, contact traveling between the head and the medium occurs in a state in which the levitation clearance of the magnetic head does not reach a desired value and is equal to or lower than a certain rotation speed.

In this way, contact traveling between the magnetic head and the magnetic recording medium occurs in various states. Generally, however, the magnetic film itself of the magnetic recording medium does not have lubricity, or even if it does have extremely low lubricity, it does not work for a long time. When contact travel occurs, the magnetic head or the magnetic film of the magnetic recording medium is abraded and so-called head crash occurs. Therefore, it is widely practiced to over coat the surface of the magnetic recording medium with a lubricant or to impregnate the magnetic recording medium with a lubricant to enhance its lubricating performance. Here, if a large amount of lubricant is used, the lubrication performance is improved, but the friction coefficient between the magnetic head and the recording medium becomes large.As a result, the magnetic head is adsorbed on the recording medium surface at the time of rotation start, and both are damaged. It is necessary to use an appropriate amount so as not to raise it.

Conventionally used surface lubricants are generally fluorocarbon liquid lubricants containing fluorine and carbon as main components. Among them, liquid lubricants called perfluoroalkyl ethers have been widely used as lubricants for magnetic disk media and magnetic tape media because they are chemically stable, have a small surface tension and are hard to evaporate. However, since this lubricant does not have a polar group in its molecule, it has a weak adhesion to the recording medium and has a drawback that the lubricant film is easily broken under severe conditions such as extreme pressure.

Therefore, CnH at the end of the molecular chain of perfluoroalkyl ether is considered to maintain the lubricating effect even under such conditions.
Lubricants in which polar groups such as COOH or COOC _n H _{2n + 1} have been substituted for _{2n + 1} (where n is an integer) alkyl have been investigated. In particular, a lubricant having two or more polar groups has a characteristic that it has a strong adhesion to the surface of the recording medium, but since the activity of the lubricant itself is high, it also adheres to the magnetic head.
There is a drawback that the friction coefficient between the magnetic head and the magnetic recording medium is high.

[Outline of Invention]

The present invention has been made in view of the above circumstances, and an object thereof is to provide a surface lubrication method for a magnetic recording medium which can secure high wear resistance and can reduce the friction coefficient between the magnetic head and the recording medium. To provide.

In order to achieve such an object, the surface lubrication method of the present invention is performed at a temperature of 60 ° C. or higher after overcoating a magnetic recording medium with a fluorocarbon-based lubricant having two or more active polar groups. It is designed to be heated and fired. Less than,
Embodiments of the present invention will be described with reference to the drawings.

〔Example〕

FIG. 1 is a characteristic diagram for use in one embodiment of the surface lubrication method according to the present invention. In this embodiment, CH ₃ —OOC—CF ₂ O (CF ₂ O) m
-(C ₂ F ₄ O) n-CF-COO-CH ₃ (where m and n are integers) The concentration of 0.005% perfluoropolyether having two polarities at the ends of the molecular chain. The solution dissolved in (1) was used as a surface lubricant, and this solution was overcoated on the surface of a magnetic disk having a γ-Fe ₂ O ₃ continuous thin film as a magnetic film and then heated and baked at a temperature of 60 ° C. or higher.

As described above, the perfluoropolyether having two polar groups overcoated on the surface of the magnetic disk is heated and fired at a temperature of 60 ° C. or more, and as shown in FIG. The coefficient of friction can be reduced. That is, FIG. 1 shows that the above-mentioned perfluoropolyether having two polar groups was overcoated on the surface of the magnetic disk at the same concentration, and heated and baked at different temperatures over a range of about 20 ° C to 140 ° C. The results of measuring the heating and firing temperature and the friction coefficient between the magnetic head and the magnetic disk are shown below.
The friction coefficient of 0.24 or more decreased by 20% at the heating and firing temperature of 60 ° C or more, and the low friction coefficient of 0.2 or less was obtained. Here, it is presumed that the reason why the friction coefficient of the lubricating film of perfluoropolyether becomes low is that the lubricating film is uniformly diffused on the magnetic disk surface and has a good lubricating surface.

FIG. 2 shows the wear depth of the magnetic film of the magnetic disk with respect to the pressing load of the ferrite ball bin when the perfluoropolyether having two polar groups according to the above-mentioned embodiment and the conventional perfluoroalkyl ether were used as the surface lubricant. It is a characteristic view which shows the result of having measured. In the figure, the characteristic curve A is the same as in the above-mentioned embodiment. Perfluoropolyether having two polar groups was overcoated on the surface of the magnetic disk at the same concentration and heated and baked at a temperature of 80 ° C., and then ferrite having a diameter of 2.3 mm was used. Corresponding to the wear depth of the magnetic film when the ball pin is pressed and slid at a speed of 1 m / s, the characteristic curve B is the ferrite under the same conditions after overcoating the magnetic disk surface with the conventional perfluoroalkyl ether. Corresponds to the ball pin pressed and slid. As is clear from the figure, when perfluoropolyether having two polar groups was overcoated at a pressing load of 10 gr (characteristic curve A), the wear depth was 0.12 μm and the perfluoroalkyl ether was overcoated. Compared with the case (Characteristic curve B), the wear depth was 1/2 or less, and good fire wear resistance was obtained.

Although the above-mentioned examples show the case where perfluoropolyether having two polar groups is used, the present invention is not limited to this, and the adhesiveness to the magnetic recording medium surface is excellent. Fluorocarbon-based lubricants having one or more active polar groups can also be used.

〔The invention's effect〕

As described above, according to the surface lubrication method of the present invention, it is possible to reduce the friction coefficient between the magnetic head and the recording medium and to obtain high wear resistance. This has the remarkable effect of extending the life and reliability of the file storage device.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing the relationship between the heating and firing temperature and the friction coefficient between the magnetic head and the magnetic disk used in one embodiment of the surface lubrication method according to the present invention, and FIG. It is a characteristic view which shows the relationship between the pressing load of the ferrite ball pin and the wear depth of the magnetic film of the magnetic disk shown by comparison.

Claims (1)

[Claims] 1. A surface of a magnetic recording medium, which comprises overcoating a fluorocarbon-based lubricant having two or more active polar groups on the magnetic recording medium, followed by heating and baking at a temperature of 60 ° C. or higher. Lubrication.