JPH0210485B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a surface lubricant applied to the surface of a magnetic recording medium.

[Conventional technology]

In a magnetic recording device such as a magnetic tape device or a floppy disk device that uses a magnetic recording medium with a magnetic film formed on a flexible substrate, the magnetic head and the magnetic recording medium are constantly connected when recording and reproducing information. Running in contact.

On the other hand, in magnetic disk devices that use magnetic recording media with a magnetic film formed on a relatively stiff aluminum alloy substrate, a floating head slider, which is a dynamic pressure type gas bearing, is used to record a magnetic recording medium that rotates at high speed. The magnetic head is levitated at minute intervals to record and reproduce information in a non-contact state. In this case, contact occurs between the magnetic head and the magnetic recording medium.

In addition, in recent years, contact start/stop (CSS) type magnetic disk drives have appeared, in which the motor is started and stopped with the magnetic head pressed against the magnetic recording medium. The magnetic head and the magnetic recording medium come into contact with each other until the recording medium reaches a certain number of revolutions, while the magnetic head and the magnetic recording medium also come into contact when the number of revolutions falls below a certain level when the magnetic recording medium stops. Contact running occurs.

In this way, contact running between the magnetic head and the magnetic recording medium occurs in various conditions, but generally the magnetic film of the magnetic recording medium itself does not have lubricity, and even if it does, the lubrication performance is extremely low. When contact running for a long time occurs, the magnetic head or the magnetic film of the magnetic recording medium wears out, resulting in a situation where information recording and reproduction becomes impossible. Therefore, in order to reduce such wear phenomena, it is widely practiced to apply a lubricant to the surface of magnetic recording media, especially magnetic disk media, to improve the lubrication performance.

Surface lubricants include solid lubricants and liquid lubricants, but traditionally for magnetic recording media,
Fluorocarbon-based liquid lubricants containing fluorine and carbon as main components, such as perfluoroalkyl polyether and perfluoropolyether, are mainly used. This type of liquid lubricant is difficult to evaporate, does not adversely affect the magnetic film, is chemically stable, and has excellent lubrication performance under normal usage conditions. In addition, since it has good wettability, it is possible to form a uniform lubricant film on the surface of the magnetic recording medium.

[Problem to be solved by the invention]

As mentioned above, in order to reduce the wear phenomenon of magnetic disk media, it is effective to apply a lubricant composed only of liquid lubricant. However, under extreme pressure conditions such as when a magnetic head and a magnetic recording medium are running in contact with each other at high speed, conventional lubricants made only of liquid lubricants have the following problems in practical use: It was difficult to apply.

First, if the amount of liquid lubricant applied is increased to reduce the wear phenomenon, the coefficient of friction will increase, and in the worst case, the magnetic head may become firmly attached to the magnetic recording medium while the device is stopped. A phenomenon occurs in which the object comes into close contact with the object. Once this adhesion phenomenon occurs,
In the CSS method, the support spring that supports the magnetic head is damaged, which prevents the magnetic head from floating and damages the surface of the magnetic recording medium, making it impossible to record and reproduce information. In particular, continuous thin film media in which magnetic films are formed using the sputtering method or plating method have flat surfaces compared to conventional coated magnetic recording media coated with iron oxide particles, so the magnetic head and magnetic recording medium surface are strong. There was a drawback that close contact occurred.

Second, because it is a liquid lubricant, the lubricant film is particularly susceptible to breakage under extreme pressure conditions, and as a result,
Wear and damage to the magnetic head and magnetic recording medium will progress. One way to prevent the lubricant film from breaking under such extreme pressure conditions is to apply a high-viscosity liquid lubricant to the surface of the magnetic recording medium. The disadvantage was that the phenomenon was more likely to occur.

The present invention eliminates the drawbacks of the liquid lubricant described above, and has a low coefficient of friction and a small amount of wear even under extreme pressure conditions, and is also good in that it does not cause breakage of the lubricant film or adhesion between the magnetic head and the magnetic recording medium. The purpose of the present invention is to provide a surface lubricant for magnetic recording media that has excellent lubrication performance.

[Means to solve the problem]

In order to achieve the above object, the surface lubricant for magnetic recording media of the present invention contains a molecular adduct of melamine and cyanuric acid, which are organic solid lubricants having cleavability, or a surfactant together with the molecular adduct. It is characterized by being dispersed in a fluorocarbon liquid lubricant.

[Effect]

According to the surface lubricant having such a structure, the surface lubricant has a molecular adduct of melamine and cyanuric acid, which are organic solid lubricants having cleavability, dispersed in a fluorocarbon liquid lubricant. Therefore, even under extreme pressure conditions, low friction and low wear can be achieved due to the sliding effect of the cleavage plane of the molecular adduct of melamine and cyanuric acid, and there is also no risk of breakage of the lubricant film or contact between the magnetic head and magnetic recording medium. Good lubrication performance is obtained in that no adhesion phenomenon occurs.

Furthermore, since the molecular adduct of melamine and cyanuric acid is dispersed in the fluorocarbon liquid lubricant using a surfactant, the molecular adduct of melamine and cyanuric acid is dispersed in the fluorocarbon liquid lubricant. The dispersibility of the oil is improved, and stable lubrication performance can be obtained. Therefore, when the surface lubricant of the present invention is applied to the surface of a magnetic recording medium for a magnetic disk device, if the same amount is applied as a surface lubricant made only of conventional liquid lubricants, the coefficient of friction and the amount of wear will be reduced. can be significantly reduced. Further, when a similar coefficient of friction is allowed, a larger amount of the surface lubricant of the present invention can be applied than conventional surface lubricants, so that it is possible to further reduce the amount of wear. On the other hand, if the same amount of wear is allowed, a smaller amount is required than with conventional surface lubricants, so the wear coefficient can be reduced.
This has the advantage that the risk of close contact between the magnetic head and the magnetic recording medium is reduced.

〔Example〕

Hereinafter, the surface lubricant for magnetic recording media of the present invention will be described in detail based on Examples.

In this example, a molecular adduct of melamine and cyanuric acid was used as the organic solid lubricant having cleavability. Since this type of organic solid lubricant has a cleavable lamellar structure, it can achieve low friction and low wear even under extreme pressure conditions due to the sliding effect of the cleavage planes. In this example, the molecular adduct of melamine and cyanuric acid was dispersed as a surface lubricant using a fluorocarbon lubricant conventionally used as a liquid lubricant as a base oil. In addition, such fluorocarbon-based liquid lubricants include perfluoroalkyl polyethers and perfluoropolyethers, and in addition to the inherent lubrication performance of lubricants, these liquid lubricants have good wettability and magnetic properties. A uniform lubricant film can be formed on the surface of the recording medium.

Furthermore, in order to promote the dispersion of the molecular adduct of melamine and cyanuric acid into the fluorocarbon-based liquid lubricant as a base oil and obtain even more excellent and uniform lubricating performance, the molecular adduct of melamine and cyanuric acid is The adduct was dispersed in the fluorocarbon liquid lubricant together with a surfactant. Various surfactants can be used, but
In this example, a fluorinated alkyl ester surfactant is used, and specific examples include perfluoroalkyl carboxylic acid, perfluoroalkyl sulfonate, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl polymethyl There are ammonium salts, etc. As mentioned above, such a surfactant not only improves the dispersibility of the molecular adduct of melamine and cyanuric acid in the fluorocarbon liquid lubricant as a base oil, but also improves the dispersibility of the molecular adduct of melamine and cyanuric acid itself. It also has some lubrication performance.

Next, the effects of the present invention will be explained with specific examples. Here, in order to evaluate the lubrication performance, two tests, a friction test and a wear test, were conducted.

In the first friction test, a winchiesta-type floating head (see Japanese Patent Publication No. 57-569) was pressed against the surface of the magnetic recording medium with a load of 6 g, and the force required to cause relative sliding between the two was measured. Then, the friction coefficient was obtained by dividing the obtained force, that is, the friction force, by the load force (6 g). Therefore, when the same amount of surface lubricant is applied, the smaller the coefficient of friction, the less the risk of strong adhesion between the magnetic head and the magnetic recording medium.

In addition, as a second wear test, a cylindrical alumina specimen with a diameter of 3 mm was pressed against the magnetic recording medium surface with a load force of 3 g, and the medium was run at a speed of 20 m/s, and the contact travel distance was 200 km. The performance of the surface lubricant was evaluated based on the wear depth of the magnetic recording medium at the time of wear. Therefore, it is natural that a surface lubricant that causes less damage to the magnetic recording medium will have superior lubrication performance when compared at the same application amount and the same contact travel distance.

Example 1 The molecular adduct of melamine and cyanuric acid, which is an organic solid lubricant having cleavability, was used at a concentration of 50% by weight, and the kinematic viscosity coefficient ν=
The surface lubricant of the present invention was prepared by dispersing it in perfluoroalkyl polyether, which is the fluorocarbon-based liquid lubricant having 800 cst.

The thus prepared surface lubricant was applied in an amount of 1.5×10 ^-3 mg/cm ² to the surface of a continuous thin film medium for a magnetic disk device on which a magnetic film was formed by a sputtering method.
Evaluations were conducted using friction and wear tests. As a result, values of a friction coefficient of 0.2 and a wear depth of 0.04 μm were obtained.

Comparative Example In order to compare the results of Example 1 with the results using only a conventional liquid lubricant, the liquid lubricant used in Example 1 was applied to the same continuous thin film medium surface for a magnetic disk device as in Example 1. When only a certain fluorocarbon-based perfluoroalkyl polyether (kinematic viscosity coefficient ν = 800 cst) was applied in an amount of 1.5 × 10 ^-3 mg / cm ² (same as in Example 1) and the same test was conducted,
The results were that the friction coefficient was 0.4 and the wear depth was 0.1 μm.

As is clear from the above results, the surface lubricant of the present invention in Example 1 has a friction coefficient of 1/2 and wear resistance compared to the conventional results in which only a liquid lubricant was used as a surface lubricant in a comparative example. It can be seen that the depth can be reduced to 2/5, and that it has extremely excellent lubrication performance.

Example 2 Molecular adduct of melamine and cyanuric acid (45% by weight), which is an organic solid lubricant with cleavability
, together with perfluoroalkylcarboxylic acid (5% by weight), which is a type of the fluorinated alkyl ester, as a surfactant, and the fluorocarbon-based perfluoroalkylpolymer having a kinematic viscosity coefficient ν = 800cst as a liquid lubricant. The surface lubricant of the present invention was prepared by dispersing it in ether (50% by weight).

The thus prepared surface lubricant was applied to the surface of a continuous thin film medium for magnetic disks on which a magnetic film was formed by the sputtering method in an amount of 1.5×10 ^-3 mg/cm ² (same as in Example 1). ) and evaluated by friction and wear tests. As a result, the friction coefficient is 0.2,
A wear depth of 0.02 μm was obtained.

Comparing this result with the results of Example 1 and Comparative Example, the friction coefficient was 1/2 of the Comparative Example, similar to Example 1, but the wear depth was 1/5 of the Comparative Example, and the Example It can be seen that the lubrication performance is even better than that of No. 1. That is, as in this example, the molecular adduct of melamine and cyanuric acid, which is an organic solid lubricant having cleavability, is mixed with a perfluoroalkyl carboxylic acid, which is a surfactant, and is a type of perfluoroalkyl carboxylic acid of the fluorinated alkyl ester. By dispersing the molecular adduct of melamine and cyanuric acid in the perfluoroalkyl polyether, which is a liquid lubricant, the dispersibility of the molecular adduct of melamine and cyanuric acid in the perfluoroalkyl polyether is improved, resulting in a more uniform It can be seen that the lubrication performance was obtained.

Example 3 The liquid lubricant used in Example 2, that is, the fluorocarbon-based perfluoroalkyl polyether (50% by weight) having a kinematic viscosity coefficient ν = 800 cst was replaced with the fluorocarbon-based perfluoroalkyl polyether (50% by weight) having a kinematic viscosity coefficient ν = 250 cst. A surface lubricant having the same composition as in Example 2 was prepared using perfluoropolyether (50% by weight).

The thus prepared surface lubricant was applied to the surface of a continuous thin film medium for magnetic disks on which a magnetic film was formed by the sputtering method in the same manner as in Example 2, in an amount of 1.5×10 ^-3 mg/c ² (same as in Example 2). ) and evaluated by friction and wear tests. As a result, the friction coefficient is 0.2,
The wear depth was 0.02 μm, and the same lubrication performance as in Example 2 was obtained.

Comparing this result with the results of a comparative example using only conventional liquid lubricant, it can be seen that the friction coefficient is 1/2 and the amount of wear is 1/5, indicating that it has extremely excellent lubrication performance. .

Example 4 Molecular adduct of melamine and cyanuric acid (97% by weight), which is an organic solid lubricant having cleavability
, together with perfluoroalkylcarboxylic acid (2% by weight), which is a type of the fluorinated alkyl ester, as a surfactant, and the fluorocarbon-based perfluoroalkylpolymer having a kinematic viscosity coefficient ν = 800cst as a liquid lubricant. The surface lubricant of the present invention was prepared by dispersing it in ether (1% by weight).

The surface lubricant prepared in this manner was applied at a rate of 1.5×10 ^-3 mg to the surface of a continuous thin film medium for magnetic disks on which a magnetic film was formed by the sputtering method, as in each of the above examples.
cm ² (same as in each of the Examples and Comparative Examples) and evaluated by friction and wear tests. As a result, a friction coefficient of 0.18 and a wear depth of 0.02 μm were obtained.

In this way, when the results of this example, in which the mixing ratio of the organic solid lubricant having cleavability into the liquid lubricant was increased, are first compared with the results of the comparative example, the coefficient of friction is about 3/7. , the wear depth is approximately 1/5, indicating that it has extremely excellent lubrication performance. Further, when compared with the results of Examples 2 and 3, it is clear that although the wear depth was almost the same, the friction coefficient showed that even better lubrication performance was obtained.

Example 5 Molecular adduct of melamine and cyanuric acid (5% by weight), which is an organic solid lubricant having cleavability
, together with perfluoroalkylcarboxylic acid (2% by weight), which is a type of the fluorinated alkyl ester, as a surfactant, and the fluorocarbon-based perfluoroalkylpolymer having a kinematic viscosity coefficient ν = 800cst as a liquid lubricant. The surface lubricant of the present invention was prepared by dispersing it in ether (93% by weight).

The surface lubricant prepared in this manner was applied to the surface of a continuous thin film medium for magnetic disks on which a magnetic film was formed by sputtering at a rate of 1.5×10 ^-3 mg/cm ² in the same manner as in each of the above examples.
(same as in each of the Examples and Comparative Examples) and evaluated by friction and wear tests. As a result, a friction coefficient of 0.25 and a wear depth of 0.03 were obtained.

In this example, since the mixing ratio of the organic solid lubricant having cleavability into the liquid lubricant is very small at 5% by weight, the friction coefficient is However, when compared with the results of the comparative example using only liquid lubricant, the friction coefficient is 5/8 and the wear depth is 3/10, which is extremely superior. It can be seen that it has excellent lubrication performance.

The results of measuring the coefficient of friction in the five examples described above are summarized in FIG. 1, and the results of measuring the depth of wear of the magnetic recording medium are shown in FIG. 2, respectively. As is clear from the figure, when the surface lubricant of the present invention was used (Examples 1 to 5), extremely superior lubrication performance was achieved compared to the conventional technology in which only liquid lubricant was used as the surface lubricant. It can be seen that it shows.

The surface lubricant for magnetic recording media of the present invention has the composition of the molecular adduct of melamine and cyanuric acid, the fluorocarbon-based liquid lubricant and the surfactant in each of the above Examples that constitute the surface lubricant, and the composition of the surfactant for magnetic disks. The amount of surface lubricant applied to the medium, or
The types of fluorocarbon-based liquid lubricants and surfactants are not limited, but other fluorocarbon-based liquid lubricants with different kinematic viscosity coefficients can be used as liquid lubricants, and other types of surfactants can be used as surfactants. The surface lubricants of the present invention may be prepared by using these materials, and as a result of conducting tests similar to those in the above-mentioned examples, satisfactory lubricating performance was obtained.

[Effects of the Invention] As explained above, the surface lubricant of the present invention has the following properties:
It has a composition in which a molecular adduct of melamine and cyanuric acid, which is an organic solid lubricant with cleavage properties, is dispersed in a fluorocarbon liquid lubricant, or together with a surfactant, so it has good performance even under extreme pressure conditions. Has lubrication performance. Therefore, when the surface lubricant of the present invention is applied to a magnetic recording medium for a magnetic disk device, if the same amount as conventional surface lubricant (liquid lubricant only) is applied, the coefficient of friction and amount of wear will be reduced. It is possible to achieve good lubrication performance that is small and does not cause breakage of the lubricant film or adhesion between the magnetic head and the magnetic recording medium. Further, when a similar coefficient of friction is allowed, a larger amount of the surface lubricant of the present invention can be applied than conventional surface lubricants, so that the depth of wear can be further reduced. On the other hand, if the same level of wear depth is allowed, a smaller amount of surface lubricant is required than with conventional surface lubricants, which reduces the coefficient of friction and improves the adhesion between the magnetic head and the magnetic recording medium. It has the advantage of reducing risks.

[Brief explanation of drawings]

FIGS. 1 and 2 are graphs showing the measurement results of the friction coefficient and the wear depth of the magnetic recording medium of each example of the surface lubricant for magnetic recording media of the present invention.

Claims (1)

[Scope of Claims] 1. A molecular adduct of melamine and cyanuric acid, which is an organic solid lubricant having cleavability, or a surfactant together with the molecular adduct is dispersed in a fluorocarbon liquid lubricant. A surface lubricant for magnetic recording media characterized by: 2. The surface lubricant for magnetic recording media according to claim 1, wherein the surfactant is a fluorinated alkyl ester type surfactant.