JPS5972652A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium superior in lubricity, abrasion resistance, and traveling stability even in high temp. and high temp. and high humidity, by forming a lubricant layer composed of fatty acid amide and fatty acid ester on the surface of a thin ferromagnetic metal film. CONSTITUTION:The surface of the thin ferromagnetic metal is coated with a soln. prepd. by dissolving >=12C fatty acid amide and >=8C fatty acid ester in 0.1-10 molar ratio in a solvent, such as benzene, toluene, alcohol, or ketone, by 1.0-0.01wt%. As a result, the obtained magnetic recording medium is stable in kinetic friction coefft. even in high temp. and high humidity, so stable in traveling performance, good in abrasion resistance, and superior in durability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to ferromagnetic metals nf, 'Fj!, which have good lubricity, abrasion resistance, and excellent durability. The present invention relates to type magnetic recording media.

Structure of the conventional example and its problems Instead of the so-called coating type magnetic recording medium in which Co-containing r-Fe2O2, CrO2 ferromagnetic powder is dispersed and applied in an organic binder, plating methods, snoktuttering, A ferromagnetic metal thin film formed by a method such as vacuum deposition or ion blating has been studied as a magnetic recording medium for high-density recording, and has already been put into practical use for audio applications.

A major problem with magnetic recording media made of ferromagnetic metal thin films is wear resistance and running stability.

This is especially true in times of high temperature and high humidity.

In the process of recording and reproducing magnetic signals, magnetic recording media
The button 7-J is subjected to high-speed movement with the magnetic head, and the movement must be smooth and stable. There must be no wear or damage caused by contact with a shattered magnetic head.

However, the ferromagnetic metal layer alone cannot withstand the harsh conditions during magnetic recording and reproducing processes, and for this reason, various types of lubricious layers are provided on the surface layer.

One method is to provide a surface oxidation layer, but this method improves wear resistance and durability, but has problems with lubricity and running stability, especially under high humidity conditions. remains.

A method for forming a uniform adsorption film of saturated fatty acids and their metal salts by the Langmuir-Blodgett method (
Japanese Patent Publication No. 56-30609). Although this method has somewhat improved wear resistance and lubricity, problems still remain with respect to lubricity and running durability under high humidity conditions (for example, 30° C., 90% RH). Also Langm
It is very difficult to form a uniform adsorption layer on the surface of a long magnetic recording medium on an industrial scale by the uir-Blogett method.

Purpose of the Invention The present invention eliminates the above-mentioned drawbacks, and even in high temperature and high humidity conditions,
The object of the present invention is to provide a magnetic recording medium having lubricity, wear resistance, and running stability.

Structure of the Invention The magnetic recording medium of the present invention has a lubricant layer made of a fatty acid amide and a fatty acid ester on a ferromagnetic metal thin film disposed on a non-magnetic base pole.

Description of Examples The fatty acid amide used in the present invention preferably has 12 or more carbon atoms, and more preferably has 22 or more carbon atoms. Examples include behenic acid amide, lignoceric acid amide, and cerotic acid amide. Fatty acid amides with carbon numbers of 11 or less may exhibit almost no lubricity.

Further, as the fatty acid ester, a monohydric or polyhydric alcohol ester of a fatty acid having 8 or more carbon atoms is desirable. In addition,
In the case of fatty acid esters having 7 or less carbon atoms, lubricity may not be observed.

Number of lubricant layers in the present invention: The mixed solution of fatty acid amide and fatty acid ester is prepared by rod coating method, air knife method,
It is formed by coating the surface of a ferromagnetic metal thin film using a method such as a gravure method, a reverse roll method, or a doctor knife method. The solvent used in the coating solution may be any solvent that dissolves fatty acid amides and fatty acid esters, such as benzene, toluene, xylene alcohols, and ketones.

The effective concentration of fatty acid amide and fatty acid ester in the lubricant solution is from 1 wt% to 0.01 wt%,
Preferably, the range is from q, 5 wt% to o, 5 wt%. The ratio of fatty acid ester to fatty acid amide is 0.
A range of 1 to 10 is valid, preferably a range of 02 to 1. The concentration of fatty acid amide and fatty acid ester is 1
If it becomes thicker than wt%, it becomes hard and precipitates, which not only reduces the adhesion of the lubricant layer but also causes a decrease in output due to so-called spacing loss. Also, 0.01wt
% or less, the sliding effect decreases and is inappropriate.

The thickness of the lubricant layer obtained by the above coating method is 100A.
However, when used as a magnetic recording medium, a thickness of 300 to 500 A is appropriate. 1
If it is less than 00A, running durability and wear resistance will be insufficient, and if it is more than 0.1μm, the distance between the magnetic head and the ferromagnetic metal thin film will become large - so-called spacing loss, which will reduce the output and increase the Density recording becomes impossible.

In addition to the wet method described above, methods for forming the lubricant layer include a dry method using vapor deposition in a vacuum. When using this method, the fatty acid amide and the fatty acid ester have different melting points and vapor pressures, so it is not possible to form a lubricant layer at the same time. When using a vapor deposition method, it is preferable to first form a monofatty acid amide on a ferromagnetic metal thin film and then form a fatty acid ester. The reason for this is that amide has a much stronger attraction force with the ferromagnetic thin film.

The ferromagnetic metal thin film in the present invention is, for example, a thin film formed of ferromagnetic metals such as cobalt, nickel, etc. and their alloys by full evaporation method. Good luck, 500
It has a film thickness of A to 4000A.

In addition, here - Cobal (SO
%) - Nickel (20%) ferromagnetic metal thin film has a -
With the i size, running becomes unstable due to friction with the magnetic head, and if it is run for a long time, it may wear out.
It is old when the output is significantly reduced due to damage or abrasive powder.

However, under high temperature and high humidity conditions, the vehicle may become unstable or not slip at all.

In this regard, in the present invention, by forming a lubricant layer consisting of fatty acid amide and fatty acid ester, the ferromagnetic metal thin film has improved wear resistance and good running stability even in high temperature and high humidity. Ta.

Next, a more specific example will be explained.

Example 1 A ferromagnetic alloy thin film ( A film thickness of 1000A) was manufactured. A coating solution having the following composition was applied to this ferromagnetic alloy thin film by the rod coach-in method.

Thereafter, it was cut into 8 widths to obtain a magnetic tape (A).

The thickness of the lubricant layer thus formed was measured with a multi-interference film thickness meter and was found to be 500X.

In this way, the coefficient of dynamic friction of the ferromagnetic alloy thin film tape with a lubricant layer and the ferromagnetic alloy thin film tape without a lubricant layer was reduced to 3.
The measurement was carried out in a room at 0°C and 90″RH.

Example 2 A coating liquid π having the following composition was applied onto a ferromagnetic thin film prepared in the same manner as in Example 1 by a reverse roll method.

Thereafter, it was cut into 8 inch widths, and the coefficient of dynamic friction with the magnetic tape (B) was measured in a room at 30° C. and 90% R).

Example 3 The following coating solution (2) was used instead of the coating solution (2) used in Example 2.

Then cut it to -3mm width to make magnetic tape (C),
The coefficient of dynamic friction was measured in a chamber at 30° C. and 90% RH.

The measurement results of the friction coefficient for each sample are shown in the table below.

On the other hand, when each sample was run on a test machine with the same functionality as a commercially available VTR (video tape recorder), it was found that the running was stable even after 11,100 hours of tape with a lubricant layer; The running of the tape without it became extremely unstable, and wear of the tape was observed.

Although the embodiments have been described with respect to magnetic tape, similar effects can be obtained with magnetic recording media such as magnetic disks and magnetic cards.

Effects of the Invention According to the present invention, by providing a lubricant layer made of fatty acid amide and fatty acid ester on a ferromagnetic metal thin film, the lubricity does not decrease even in high temperature and high humidity, and running stability and wear resistance are good. Therefore, a magnetic recording medium with excellent durability can be easily obtained.

Claims (3)

[Claims] (1) A magnetic recording medium characterized in that a lubricant layer made of a fatty acid amide and a fatty acid ester is provided on a ferromagnetic metal thin film provided on a nonmagnetic substrate. (2) The magnetic recording medium according to claim 1, wherein the fatty acid amide is a fatty acid amide having 12 or more carbon atoms. (3) The magnetic recording medium according to claim 1, wherein the fatty acid ester is a fatty acid ester having 8 or more carbon atoms.