JPH0731806B2 - Magnetic recording medium - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high recording density magnetic recording medium used in the information industry field and the like.

2. Description of the Related Art Instead of a conventional coating type magnetic recording medium, a magnetic recording medium in which a ferromagnetic metal thin film is provided on a non-magnetic substrate by a method such as a plating method, a sputtering method, a vacuum deposition method, an ion plating method is It has been studied as a magnetic recording medium for high recording density.

However, the magnetic recording medium using the ferromagnetic metal thin film produced by the above method has problems in abrasion resistance and running property.

The magnetic recording medium is used for recording and reproducing magnetic signals.
Placed in high-speed relative motion with the magnetic head. At this time, the running of the magnetic recording medium must be smooth and stable. Also, no wear or damage due to contact with the magnetic head should occur.

However, the ferromagnetic metal thin film formed by the above-described method cannot withstand the harsh conditions of the magnetic recording and reproducing processes, and the traveling becomes unstable due to the friction of the magnetic head etc., or the traveling for a long time. In such a case, the output may be significantly reduced due to abrasion, damage, or generation of abrasion powder. Therefore, it has been proposed to form a film made of mono-linear saturated alkylamine as a protective film on the ferromagnetic metal thin film (Japanese Patent Laid-Open No. 59-119538).

Problems to be Solved by the Invention However, in this case, although the initial lubricity is slightly improved, the lubricity is not durable. This is because the bond between the mono-linear saturated alkylamine and the magnetic film is such that the physical adsorption is weak, so that the mono-linear saturated alkylamine is scraped off by a magnetic head that slides during running.

The present invention has been made in view of the above points, and an object thereof is to provide a magnetic recording medium having excellent sliding durability.

Means for Solving Problems A silica / alumina or silica / nickel oxide containing layer is formed on a ferromagnetic metal thin film provided on a non-magnetic substrate,
A higher aliphatic amine-containing layer is formed thereon.

Work Silicon compounds such as silica / alumina or silica / nickel oxide are strongly acidic compounds. Therefore, the higher aliphatic amine, which is a basic compound, strongly chemisorbs to the silicon compound. As a result, in the magnetic recording medium in which the silicon compound-containing layer is formed and the higher aliphatic amine-containing layer is formed thereon, the higher aliphatic amine that is the lubricant is scraped off from the magnetic surface even when the magnetic head is rubbed. Therefore, a magnetic recording medium excellent in sliding durability can be obtained.

EXAMPLE FIG. 1 is a sectional view of a magnetic recording medium of the present invention. In the figure, 1 is a non-magnetic substrate, 2 is a ferromagnetic metal thin film, 3 is a silicon compound containing layer, and 4 is a higher aliphatic amine containing layer.

Examples of the non-magnetic substrate 1 that can be used in the magnetic recording medium according to the present invention include polymeric materials such as polyvinyl chloride, cellulose acetate, polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, polyimide, polyamide, non-magnetic metal materials, glass, and porcelain. There are films and plates made of known materials such as ceramic materials.

As the ferromagnetic material that can be used to form the ferromagnetic metal thin film 2 that can be used in the porcelain recording medium of the present invention, any known material can be used. For example, one or more alloys of iron, cobalt, nickel, or these materials can be used. And other metals such as manganese, chromium, titanium, yttrium phosphorus, samarium, bismuth, and the like, and oxides of the above metals.

The ferromagnetic metal thin film 2 can be formed on the non-magnetic substrate 1 by any known method such as a vacuum deposition method, a sputtering method, an ion plating method, and a plating method.

In the present invention, the essential point is to form the silica / alumina or silica / nickel oxide containing layer 3 on the ferromagnetic metal thin film 2 as described above, and to provide the higher aliphatic amine containing layer 4 thereon.

The silica content in silica / alumina and silica / nickel oxide is preferably 40% to 90% in terms of molar ratio, and this ratio strongly adsorbs higher aliphatic amines.

For silica / alumina, a method in which silica gel and alumina gel are kneaded in a wet state, a method in which aluminum salt is immersed in silica gel, a method in which silica and alumina are simultaneously gelled from an aqueous solution, and an alumina gel is deposited on silica gel It is made by any one of a method, a method in which silica powder and an alumina powder are mixed, compressed, and hardened.

Silica / nickel oxide is produced in the same manner as silica / alumina.

When the silica / alumina or silica / nickel oxide containing layer 3 is formed on the ferromagnetic metal thin film 2 according to the present invention, it can be formed by a sputtering method.

When the silica / alumina or silica / nickel oxide-containing layer 3 is formed on the ferromagnetic metal thin film 2 according to the present invention, the film thickness is preferably 5 to 40 nm.

When the film thickness was more than 50 nm, the output decreased due to spacing loss during signal reproduction. If it is smaller than 5 nm, pinholes are likely to be formed, and a composite effect with higher aliphatic amine cannot be expected.

According to the present invention, the higher aliphatic amine-containing layer 4 is provided on the silica / alumina or silica / nickel oxide-containing layer 3 described above.

The higher aliphatic amine that can be used in the present invention is a compound containing a hydrocarbon chain having 12 to 26 carbon atoms. When the carbon number is 11 or less, sufficient lubricity cannot be obtained. Further, in the case of an aliphatic amine having a hydrocarbon chain having 27 or more carbon atoms, no further improvement in lubricity is observed and durability is reduced.

Examples of the higher aliphatic amine that can be used in the present invention include laurylamine, tetradecylamine, hexadecylamine, stearylamine, icosylamine, docosylamine, tetracosylamine and hexacosylamine.

The higher aliphatic amine-containing layer 4 may be formed on the silica / alumina or silica / nickel oxide-containing layer 3 by a method such as a vacuum vapor deposition method, a coating method, or a Langmuir-Blodgett method.

When the higher aliphatic amine-containing layer 4 is formed on the silica / alumina or silica / nickel oxide-containing layer 3 according to the present invention, the film thickness is preferably 5 to 45 nm, and 10 to 30 nm.
Is preferred. However, the total thickness of the silica / alumina or silica / nickel oxide-containing layer 3 needs to be 50 nm or less. When it is larger than 50 nm, the output is lowered due to spacing loss when reproducing the signal, which is not preferable. Further, if the film thickness of the higher aliphatic amine-containing layer 4 is less than 5 nm, the lubricity is significantly reduced, which is not preferable.

The present invention will be described below with reference to specific examples.

〔Example〕

Film thickness consisting of cobalt (90%)-chromium (10%) on a 20 μm thick polyimide film substrate by vacuum deposition.
A ferromagnetic metal thin film of 150 nm was made. Cut a piece with a diameter of 75 mm from the substrate on which this ferromagnetic metal thin film is formed,
On the ferromagnetic metal thin film, an argon gas was introduced to form a silica / alumina or silica / nickel oxide containing layer having a film thickness of 10 nm by a high frequency sputtering method. Argon gas pressure was set to 2 × 10 ⁻⁴ Torr, and each silicon compound having the following composition was used as a target.

Samples 1 to 3 Silica / alumina (SiO ₂ : Al ₂ O ₃ = 1: 1 molar ratio) Samples 4 to 6 Silica / nickel oxide (SiO ₂ : NiO = 2: 1 molar ratio) Next, using a spinner, Of 100 ppm higher aliphatic amine in isopropanol was coated onto the silica-alumina or silica-nickel oxide containing layer.

Samples 1 and 4: Laurylamine Samples 2 and 5: Stearylamine Samples 3 and 6: Hexacosylamine 2cc of the above amine solution was applied at a rotation of 500 rpm, and then the rotation speed was increased to 1000 rpm to dry the solvent. Let
After vacuum drying the sample, use silica / alumina or silica /
When the higher aliphatic amine layer formed on the nickel oxide-containing layer was measured by an ellipsometer, the film thickness was 15 nm.

[Comparative example]

In the above example, the higher aliphatic amine was directly spin-coated under the same conditions without forming the silica-alumina or silica-nickel oxide-containing layer on the ferromagnetic metal thin film.

Sample 7: Laurylamine Sample 8: Stearylamine Sample 9: Hexacosylamine The dynamic friction coefficients of Samples 1 to 6 of Examples and Samples 7 to 9 of Comparative Examples were measured with a dynamic friction coefficient meter (DFPM type, manufactured by Kyowa Kagaku). . The head is a SUJ steel ball with a diameter of 12 mm, the head load is 100 g,
The head traveling speed was measured at 1.0 mm / s. The results are shown below.

From the data in the table, the magnetic recording media of the examples (Samples 1 to 6) according to the present invention have a low dynamic friction coefficient even after 200 reciprocations, as well as the initial dynamic friction coefficient. ) Is better than that.

When these magnetic recording media were run on a tester having a function equivalent to that of a commercially available floppy disk, running of all the magnetic recording media of the examples was stable even after 100 hours, and no abrasion scratch was observed. It was On the other hand, the magnetic recording medium of the comparative example became unstable in running, and abrasion scratches were found on the magnetic surface.

Although the magnetic disk is shown in the above embodiment,
The magnetic recording medium of the present invention is obviously applicable to magnetic tapes, magnetic cards and the like.

EFFECTS OF THE INVENTION The magnetic recording medium of the present invention has excellent sliding durability and can maintain it for a long period of time.

[Brief description of drawings]

The figure is a cross-sectional view of a magnetic recording medium in an example of the present invention. 1 ... Non-magnetic substrate, 2 ... Ferromagnetic metal thin film, 3 ... Silica / alumina or silica / nickel oxide containing layer, 4
...... Higher aliphatic amine-containing layer.

Claims (3)

[Claims] 1. A magnetic recording medium in which a silica / alumina or silica / nickel oxide-containing layer is formed on a ferromagnetic metal thin film provided on a non-magnetic substrate, and a higher aliphatic amine-containing layer is provided thereon. 2. The magnetic recording medium according to claim 1, wherein the silica-alumina or silica-nickel oxide-containing layer has a thickness of 5 to 40 nm. 3. The magnetic recording medium according to claim 1, wherein the higher aliphatic amine contains a hydrocarbon chain having 12 to 26 carbon atoms.