JPH07108384B2 - Surface lubrication method for magnetic disk media - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface lubrication method for a magnetic disk medium, and more particularly to a novel surface lubrication for a magnetic disk medium which forms a uniform lubricating film on the surface of the magnetic disk medium. Concerning the law.

2. Description of the Related Art In a magnetic recording 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 such as PET, a magnetic head and The magnetic recording medium is running in contact.

On the other hand, in a magnetic disk device using a magnetic disk medium having a magnetic film formed on a rigid substrate such as aluminum, a floating head slider, which is a dynamic pressure gas bearing, is used to form a small clearance between the magnetic head and the magnetic disk on the disk medium rotating at high speed. Recording and reproducing are performed while keeping the above.

In the case of such a magnetic disk device, when the floating clearance of the magnetic head is reduced due to disturbance such as dust mixing, mechanical components such as a positioner, and vibration of the magnetic disk medium,
The magnetic head and the magnetic disk medium contact intermittently at high speed.

Further, in recent years, a contact start stop (CSS) type magnetic disk device in which a disk head starts to rotate while a magnetic head is in contact with the magnetic disk medium and is rotated and stopped by a drive motor has become mainstream. ing. In such a system, when the number of revolutions of the disk medium is below a predetermined value, the clearance between the magnetic head and the magnetic medium does not reach a predetermined value, so that contact traveling between the head and the medium occurs.

In such a case, the magnetic film itself of the magnetic disk medium does not have lubricity, or even if it does have extremely low lubricity, the magnetic film of the magnetic head or the magnetic disk medium is abraded by long-time contact running. The so-called head crash occurs.

In order to avoid such a problem, generally, the surface of the magnetic disk medium is coated with a lubricant to improve its lubricity.

However, when a large amount of such a lubricant is used on the whole or a part of the surface of the disk medium, the lubricating film becomes thick and the friction coefficient between the head and the disk medium becomes large. For this reason, the head and the disk medium may be attracted to each other when the drive motor starts rotating, and both may be damaged.

Therefore, it is necessary to use an appropriate amount of the lubricant coating the surface of the disk medium within a range where the friction coefficient is not increased and to form a uniform thin film.

Particularly, in a continuous thin film medium with a magnetic film formed by a sputtering method or a plating method, the surface is smoother than that of a conventional coating medium coated with iron oxide fine particles, so it is magnetic to form an extremely thin lubricating film of 10 to 100Å. This is important in preventing the head and the magnetic disk medium from sticking to each other.

Problems to be Solved by the Invention As a method for applying a lubricant to a continuous thin film medium having a magnetic film formed by a sputtering method or a plating method as described above, there are a spin coating method, a spray method, a dipping method, and the like. The film is formed by applying a lubricant solution diluted with an organic solvent to the medium by such a method and then heating the medium to evaporate the lubricant solvent.

In the coating method as described above, the step of heating the magnetic disk medium and evaporating the lubricant solvent to form the lubricant film has been conventionally performed in the atmosphere. However, in such a solvent removal method, it takes time to evaporate the solvent, and moreover, the lubricant molecules having a weak bonding force with the surface of the magnetic disk medium remain, so that the lubricant molecules themselves agglomerate and the like. Moreover, it was difficult to form a thin lubricating film.

An object of the present invention is to provide a surface lubrication method for a magnetic disk medium capable of forming a lubricating film having a thickness of 10 to 100Å with a uniform thickness on a magnetic disk medium and stably obtaining a low friction coefficient with a magnetic head. To provide.

Means for Solving the Problems The inventors of the present invention have conducted various studies and studies to solve the above-mentioned drawbacks in the surface lubrication method for magnetic disk media, and as a result of repeated research, applied a lubricant solution to the surface of the magnetic disk media. After that, by heating in a vacuum atmosphere, it is possible to remove, together with the solvent, a lubricant solvent having a weak bonding force with the medium surface,
The present invention has been completed by discovering that a lubricating film having a uniform thickness can be formed.

That is, the surface lubrication method of the magnetic disk medium of the present invention is
A lubricant solution diluted with a solvent is applied to the surface of the magnetic disk medium, the magnetic disk medium is heated in a vacuum atmosphere to remove the solvent, and a lubricant film is formed on the magnetic disk medium.

In the lubrication method according to the present invention, the present invention can be effectively carried out if the pressure of the vacuum atmosphere for heating the medium is preferably 10 ^-1 Torr or less.

The heating temperature in the vacuum atmosphere is preferably in the range of 80 ° C to 400 ° C, and the heating time is determined depending on the properties of the lubricant and solvent in the lubricant solution.

Examples of the lubricant that can be used in the present invention include perfluoropolyether having a polar group at the molecular end, liquid fluorocarbon, solid fluorocarbon, a mixture of liquid fluorocarbon and solid fluorocarbon, higher fatty acid, A higher fatty acid metal salt or a mixture of a higher fatty acid and a higher fatty acid metal salt can be used.

As a method of applying these lubricant solutions, any conventionally used method such as spin coating, spraying or dipping can be used.

Further, the magnetic disk medium to which such a lubricant solution is applied may be one in which a protective film such as SiO ₂ or carbon is provided on the surface of the magnetic film.

Function The present invention is characterized in that the surface of the magnetic disk medium is coated with the lubricant solution and then heated in a vacuum atmosphere of a predetermined pressure. By heating in such a vacuum atmosphere, the lubricant molecules and the lubricant solvent, which originally have a weak bonding force with the medium surface, are simultaneously removed from the medium surface, and a uniform lubricating film can be formed. By heating in a vacuum atmosphere, evaporation of lubricant molecules and lubricant solvent can be accelerated.

At this time, if the pressure of the vacuum atmosphere exceeds 10 ^-1 Torr, it is difficult to evaporate the lubricant solvent in a short time. Further, when the heating temperature in the vacuum atmosphere is lower than 80 ° C., it takes time to evaporate the lubricant solvent, and it becomes difficult to remove the lubricant molecules having a weak bonding force with the medium surface. On the other hand, if the heating temperature is
If the temperature exceeds 400 ° C, the lubricant itself will evaporate and the lubricating film will be damaged.

EXAMPLES Hereinafter, the surface lubrication method for the magnetic disk medium of the present invention will be described in detail with reference to specific examples, but the present invention is not limited to the following examples.

FIG. 1 shows an example of a heating closed container used for carrying out the present invention.

As shown schematically in FIG. 1, a closed container 1 having a vacuum chamber capable of being closed inside has a pair of upper and lower heaters 2 for mainly radiatively heating a substance placed in the vacuum chamber and a vacuum chamber. An intake pipe 10 is provided which connects the chamber and the exhaust pump 9. Further, in order to externally monitor the state of the vacuum chamber set by these means, a temperature sensor 5 protruding into the vacuum chamber and a temperature display unit 6 for numerically displaying the heating temperature measured by the temperature sensor 5, and A pressure display unit 4 for detecting and displaying the degree of vacuum of the atmosphere in the vacuum chamber is provided. Further, a timer 3 is also provided, which measures the operation time of these exhaust means and heating means and automatically stops these operations when a predetermined time has elapsed.

Further, a disk mounting jig 8 for mounting the magnetic disk medium 7 is arranged in the closed container 1.

In FIG. 1, first, the heater 2 is turned on to keep the inside of the heating closed container 1 at 100 ° C. On this occasion,
The temperature can be detected by the temperature sensor 5 and read by the temperature display unit 6. Next, the Ni-Co-P plating medium is coated with SiO ₂
A magnetic disk medium coated with a protective film consisting of a medium 7 coated with a 0.07% fluorinated carbon solution of perfluoropolyether having a polar group at its molecular end is mounted on a disk mounting jig 8 and a hermetically sealed container 1 for heating is attached. Charge inside.

Then, the exhaust pump 9 exhausts the inside of the closed container through the intake pipe 10, and while confirming the internal pressure on the pressure display unit 10,
^The pressure is reduced to ^-1 Torr, a vacuum atmosphere is created, and heating is performed for 2 hours.

The internal temperature of the heating closed container 1 may be set after depressurization, and this time can be set by the timer 3.

FIG. 2 shows the results of measuring the lubricating film thickness of the magnetic disk obtained by the above operation at intervals of 90 ° in the circumferential direction.

2 indicates the film thickness of the lubricating film formed by the method of the present invention, and ● indicates the one formed by the conventional method. In the conventional method, heating was performed in the atmosphere. Here, the thickness of the lubricant solvent formed on the surface of the magnetic disk before heating was 40 ± 2Å in both the embodiment of the present invention and the conventional method.

As is apparent from FIG. 2, it was found that the lubricant film formed by the method of the present invention was extremely uniform in the circumferential direction of the magnetic disk as compared with the conventional method.

FIG. 3 shows the relationship between the lubricating film thickness and the friction coefficient. As shown in Fig. 3, it can be seen that the friction coefficient gradually increases with an increase in the lubricating film thickness, and increases sharply when the lubricating film thickness exceeds 20Å. In the conventional method shown in Fig. 2, there is a portion where the film thickness exceeds 20Å on the surface of the magnetic disk medium. The friction coefficient sharply increases at this portion, and the stability at the time of head / medium contact traveling decreases and the risk of head crash. It can be seen that

EFFECTS OF THE INVENTION According to the lubrication method of the present invention, the lubricating film on the surface of the magnetic disk medium is uniformly formed with a thickness of 10 to 100 Å and with good reproducibility, and good lubricating characteristics can be obtained. Therefore, the reliability of thinning the lubricating film is improved, the recording density is high, and the operational stability of the head is remarkable, and the floating head of the magnetic head is reduced, and it is applied to the magnetic disk device adopting the CSS method, etc. Is extremely effective.

[Brief description of drawings]

FIG. 1 is a schematic view of a heating closed container for carrying out the method of the present invention, and FIG. 2 is a view showing a film thickness distribution of a lubricating film formed by the present invention and a conventional lubrication method, FIG. 3 is a diagram showing the relationship between the lubricating film thickness and the friction coefficient. (Main reference numbers) 1 ... Airtight container for heating, 2 ... Heater, 3 ... Timer, 4 ... Pressure display, 5 ... Temperature sensor, 6 ... Temperature display, 7 ... Magnetic disk medium , 8 ... disk mounting jig, 9 ... exhaust pump, 10 ... intake pipe

Claims (1)

[Claims] 1. A magnetic disk medium surface is coated with a lubricant solution diluted with a solvent at room temperature, and then the magnetic disk medium is heated in a vacuum atmosphere at a pressure of 10 ^-1 Torr or less at a temperature in the range of 80 to 400 ° C. A method for surface lubrication of a magnetic disk medium, which comprises heating at a temperature to remove the solvent and forming a lubricating film on the magnetic disk medium.