JP2780270B2 - Magnetic recording media - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording medium used in a magnetic recording device such as a magnetic disk device, and more particularly to an improvement in durability of the medium.

[Prior art] In a magnetic recording medium for performing high-density recording such as a hard magnetic disk, plating, sputtering, and the like are performed in place of the conventional coating type medium using a coating type magnetic film including a magnetic powder and a binder. Metal magnetic thin film media formed by a method such as vapor deposition have been used.

When performing recording and reproduction on a hard magnetic disk, a small air layer is formed between the magnetic head and the magnetic disk by giving a predetermined rotation to the disk, and the CSS method (recording / reproduction in this state) Generally, a contact start / stop method is used.

In the CSS method, the head and the magnetic disk surface are in physical contact with each other in the stopped state, and the head and the magnetic disk move relative to each other in a contact friction state at the start of rotation or at the end of rotation. The frictional force at this time causes wear of the head and the magnetic disk surface to progress. Also, during recording and reproduction, the head may contact the magnetic disk surface at high speed due to the presence of minute dust or the like, and a large frictional force may act between the head and the magnetic disk surface to destroy the head or the magnetic film.

In particular, in a metal magnetic thin film medium, the above problem is remarkable because the metal magnetic film has a large friction coefficient and a small film thickness. Therefore, conventionally, a carbon protective film is formed on the metal magnetic film to provide corrosion resistance and lubricity, or a magnetic lubricant is applied on the carbon protective film with a liquid lubricant applied thereon as shown in FIG. Medium was used. (For example,
Also, attempts have been made to increase the bonding force with the carbon film by using a liquid lubricant having a functional group as the liquid lubricant. (For example, Japanese Patent Application Laid-Open No. 62-66417) [Problems to be Solved by the Invention] However, in the conventional magnetic recording medium as shown in FIG.
When S was repeated, the effect of the lubricant gradually decreased and the frictional force increased, and sufficient wear resistance and damage resistance were not obtained.

Furthermore, when a lubricant having a functional group is applied,
At the same time as the bonding force with the carbon film is increased, the bonding between the lubricating oils is also increased, so that there is a problem that the running property of the head is deteriorated.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned conventional problems, and has a carbon protective layer for improving durability on a surface of a magnetic recording layer formed on a substrate. In a magnetic recording medium having a film formed thereon and a lubricant applied on the outermost surface, a coupling agent layer is formed between the carbon protective film and the lubricant.

The coupling agent is a general term for a group of substances that generally participate in the interaction between the inorganic substance and the organic substance, and examples of the coupling agent include silane, titanate, aluminum, and zircoaluminate.

All of these substances are organometallic compounds or metal complexes, and are compounds having both a portion that easily bonds to an inorganic substance and a portion that easily bonds to an organic substance in one molecule.

All of the parts that easily bond to the inorganic substance have a structure in which an alkoxy group is bonded to a metal atom, and the bond to the inorganic substance surface is formed in such a manner that the alkyl group alternates with a metal atom or a carbon atom on the inorganic substance surface.

The portion that easily bonds to an organic substance generally has a long-chain alkyl group or a structure having a functional group at the terminal of a polymethylene group, and forms a bond by harmony or reaction with the organic substance in this portion.

It is preferable to use an aluminum-based coupling agent, a titanate-based coupling agent, or the like on the surface of the carbon protective film. In particular, acetoalkoxyaluminum diisopropylate, which is an aluminum-based coupling agent (product name)
AL-M (manufactured by Ajinomoto Co., Inc.) and isopropyl tri (N-aminoethyl-aminoethyl) titanate (product name: KR44 Ajinomoto Co., Ltd.), which is a titanate-based coupling agent, show good characteristics.

The coupling agent layer and the lubricant, for example, dipping the magnetic recording medium on which the carbon protective film is formed into a coupling agent solution diluted with a solvent, and after pulling up, washing off the coupling agent of the terminal bond, It is formed by a method of applying a lubricant diluted with a solvent by a method such as a dipping method.

As the lubricant, a fluorocarbon such as perfluoroalkyl polyether is preferable, and in particular, a lubricant having a structure having a benzene ring at a terminal and having no polar group or reactive group (for example, a product example of Fomblin AM2001: manufactured by Montegisson, Italy) ) Is preferable because it exhibits good head running properties and a strong bonding force to the carbon protective film, and exhibits excellent lubricity and durability.

In the above application step, after applying the coupling agent, it is preferable to perform a heat treatment at a temperature in the range of 60 ° C. to 200 ° C. because the effect of increasing the adhesive force of the lubricant to the disk by the coupling agent is remarkably promoted.

In order to simplify the process, a solution in which both the coupling agent and the lubricant are dissolved in a solvent in advance may be applied. Also in this case, good effects can be obtained by heat treatment after application.

[Function] The carbon protective film is usually formed on a substrate at a temperature from room temperature to about 300 ° C. by a vacuum evaporation method or a sputtering method. Since the carbon film formed in this way is chemically stable and has no polarity, it is generally considered that it is difficult to strongly bond it to another substance. However, the film has an amorphous structure, and the film surface has a large number of dangling bonds of unpaired electrons and hydroxyl (≡C-OH) groups resulting from the reaction of moisture and the like in the atmosphere. It is thought that it is.

When a coupling agent is applied to the upper part of the carbon film having these dangling bonds or hydroxyl groups, a chemical bond between the two occurs,
The surface of the carbon film is coated with molecules constituting the coupling agent to change the properties and increase the bonding force with the lubricant.

According to the present invention, the carbon protective film and the aluminum-based coupling agent layer are strongly bonded by a chemical bond, and the lubricant applied on the aluminum-based coupling agent layer is
Due to the physical entanglement with the organic group constituting the coupling agent and the increased van der Waals force due to the shortened distance, it is also possible to enable the chemical reaction between the lubricant and the coupling agent organic substance. Thereby, the aluminum-based coupling agent is strongly held, and as a result, the bonding force between the carbon protective film and the lubricant is enhanced.

[Example] <Example 1> Hereinafter, the present invention will be described in detail with reference to examples.

FIG. 1 is a sectional view showing the structure of the magnetic recording medium of the present invention. In the drawing, the magnetic recording medium of the present invention is formed by depositing chromium (Cr) as a base layer 2 on a chemically strengthened glass disk 1, and forming a cobalt-nickel-chromium (Co- Ni—Cr) alloy is deposited to a thickness of about 50 mm. Furthermore, a carbon film of about 40
Deposit a nm film. In this case, the base film 2, the metal magnetic film 3, and the protective film 4 are formed on the glass substrate 1 by a sputtering method.

To this disk, acetoalkoxyaluminum diisopropylate (AL-M) as a coupling agent was diluted to 0.01% with a solvent, trichlorotrifluoroethane, and applied by a dipping method.

Thereafter, the disc was left at 110 ° C. for 1 hour, and the unbound coupling agent was washed away with a solvent. On top of this, perfluoroalkyl polyether (Fomb
lin AM2001) with the solvent trichlorotrifluoroethane in 0.5
% And applied by dipping method and 110 ℃
For 5 minutes.

Here, the heat treatment applied after the application of the coupling agent and after the application of the lubricant is for increasing the reactivity between the carbon protective film and the coupling agent, and between the coupling agent and the lubricant.

When the adhesive force between the lubricant 5 and the carbon protective film 4 of the disk of the present invention was examined, as shown in FIG. 2, the disk of the present invention was twice as large as the disk having only the lubricant coated on the carbon protective film. It was found that there was the above adhesive force. The adhesion was measured by washing the disk with a solvent and measuring the remaining amount of the lubricant thereafter.

In addition, when the disk was rotated at a high speed of 3600 rpm and subjected to a test in which the head was repeatedly taken off and on (hereinafter referred to as a CSS test), the disk without the coupling agent showed wear marks on the disk surface in 2000 times. No discs showed any more on the disc surface after 20,000 tests.

<Example 2> An isopropyl tri (N) was used as a coupling agent on a disk substrate fabricated in the same manner as in Example 1 and having a carbon protective film formed thereon.
A solution obtained by diluting (aminoethyl-aminoethyl) titanate (KR44) to a concentration of 0.01% with the solvent isopropyl alcohol was applied by dipping.

After the disc was left at 110 ° C. for 1 hour, the uncoupled coupling agent was washed off with a solvent, and the same lubricant 5 as in Example 1 was applied thereon by the same procedure. Thereafter, the disk was left at 110 ° C. for 5 minutes. The adhesion was measured in the same manner as in Example 1 (see FIG. 2), and a CSS test was carried out. As a result, the disk of the present invention had twice or more the amount of adhesion as compared to a disk having only a carbon protective film coated with a lubricant. It turned out to be strong, and no abnormalities were seen on the disk surface even after 20,000 CSS tests.

Comparative Example 1 A conventional magnetic recording carrier in which a lubricant was applied without providing a coupling agent layer on a carbon protective film produced in the same manner as in Example 1 was similar to Example 1 as in Example 1. The adhesive force of the lubricant was measured. The results are shown in FIG. The adhesion of the lubricant was inferior to the example.

[Effect of the Invention] As described above, in the present invention, since the layer of the aluminum-based coupling agent is provided between the carbon protective film on the metal magnetic material and the lubricant, the adhesive force of the lubricant is significantly improved, A magnetic recording medium having excellent lubricity and wear resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing a cross section of a magnetic recording medium of the present invention, FIG. 2 is a view showing the remaining amount of lubricant after a lubricant-coated disk has been washed with a solvent, and FIG. FIG. 3 is a sectional view of a medium.

Claims (1)

(57) [Claims] A magnetic recording layer formed on a substrate, wherein a carbon protective film for improving durability is formed on a surface of the magnetic recording layer; A magnetic recording medium comprising an aluminum-based coupling agent layer formed between a film and a lubricant.