JPS593726A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent the surface corrosion of a magnetic recording medium by sticking a corrosion inhibitor contg. phenol ether as a principal component on the ferromagnetic metallic thin film contg. oxygen. CONSTITUTION:A single-layer or multilayered ferromagnetic metallic thin film of 0.05-0.5mum thickness is formed on a nonmagnetic substrate by vapor deposition, sputtering or other method in a vacuum where a very small amount of gaseous oxygen is present. The thin film consists of diagonal or vertical prismatic crystals and contains oxygen by 3-45atomic% of the amount of the magnetic metal such as Co or Fe. A corrosion inhibitor contg. phenol ether as a principal component is stuck at least on the surface of the film. It is incorporated into the film if possible. 3-Hydroxy-4-nitrosophenyl methyl ether, 4- nitrophenyl methyl ether, 4-nitrophenyl ethyl ether or the like is used as the phenol ether.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ferromagnetic metal thin film magnetic recording medium with improved corrosion resistance in high humidity.

Fe, Nl, eCO or an alloy thereof is applied to the surface of a substrate made of a plastic film such as polyester or polyimide, or a non-magnetic material such as an aluminum plate or a glass plate, by vapor deposition, ion blasting, sputtering, etc. in a vacuum. A magnetic recording medium in which a ferromagnetic thin film containing oxygen as a main ingredient is formed is suitable for high-density recording such as video signal recording.
Because it is small (5 to 0.6 μm), if it is left in high humidity, especially in an environment where temperature changes are large and condensation occurs, it is likely to cause corrosion on the surface. It affects the characteristics and also deteriorates practical characteristics such as head touch and wear resistance.

When suppressing this corrosion with a rust preventive agent, there is a strict limit to the thickness of the protective film that can be formed on the surface of the magnetic layer due to the spason gloss between the head and the magnetic layer. There was a desire for a rust preventive agent that had an anti-corrosion effect. F
Ferromagnetic thin films that are mainly made of e, Ni, Go, or their alloys and contain oxygen have higher coercive force and superior corrosion resistance than thin films made of pure metals. A material that exhibits a rust-preventing effect because it is partially oxidized.
However, the known anti-corrosion agents used for bulk metals such as Fe, Co, and Ni are not necessarily suitable; in fact, when these anti-rust agents are applied, they may actually accelerate corrosion. It became necessary to find a new material that was compatible with ferromagnetic thin films containing oxygen.

As a result of various studies, the present inventors have found that a rust preventive agent containing phenol ethers as a main component is suitable as a rust preventive agent for ferromagnetic thin films containing oxygen. That is, the present invention provides a magnetic recording medium in which a ferromagnetic metal thin film containing oxygen is formed on a non-magnetic substrate, in which a rust preventive agent containing phenol ethers as a main component is attached to the ferromagnetic metal thin film. It is characterized by:

A metal plate such as an aluminum plate or a stainless steel plate, or an inorganic plate such as a glass plate is used, and evaporation is performed on these directly or through a nonmagnetic thin film layer in a vacuum in the presence of a trace amount of oxygen gas. Made of diagonal or vertical columnar crystals with a thickness of 0.05~ by sputtering, io/blating, etc.
0.5 μm Go, Fe.

Fe-Ni, Go-Ni, Fe-co, F
A rust preventive agent containing phenol ethers as a main component on a single-layer or multi-layer ferromagnetic thin film containing e-N1-Go, etc., and containing 3 to 46% oxygen in atomic ratio to the magnetic metal. apply.

-hydroxy-4-nitrosophenylmedel ether,
4-nitrophenyl methyl ether, 4-nitrophenylethyl ether, 2,4-sinitrophenyl menal ether, bis(2,4,6-trinitrophenyl) ether, phenyl menal ether, phenylethyl ether, phenyl vinyl ether, etc. be.

The rust preventive agent in the present invention may be a single substance or a mixture of two or more of these, and may contain organic compounds other than phenol ethers, if necessary, such as naphthols, hydroquinones, etc. It contains small amounts of acetophenones, quinones, etc.

These anti-corrosion agents exhibit their effects by being present at least on the surface of the ferromagnetic thin film, if possible inside, or in contact with the interface with the base on which the ferromagnetic thin film is formed. The appropriate amount is about 0.5 to 5 oomg per 1M of magnetic recording medium. Specifically, the rust preventive agent is applied on the surface of the ferromagnetic thin film, either by itself or mixed with a film-forming agent such as a polymer compound, diluted with a solvent if necessary. A method in which rust preventive vapor is applied to the surface of the ferromagnetic thin film.Furthermore, if the magnetic recording medium is in the form of a tape, it is placed on the back side and transferred to the surface of the ferromagnetic thin film when the tape is rolled up. Well-known means such as a method of forcing the temperature to rise can be used. In addition to the rust preventive agent, it is also possible to use ordinary lubricants, antistatic agents, and other additives.

Next, embodiments of the present invention will be specifically described.

A polyester film with a thickness of 10 μm was placed along the circumferential surface of a cylindrical can, and oxygen gas was introduced at a rate of 0.31/1 m at a vacuum level of 5 x 10-5 Torr, and a CoNi alloy (containing Ni) was melted by electron beam heating. Amount 20
wt%) was continuously obliquely deposited (low incidence angle variation component 30 or less cut) to form a 1000X thick oxygen-containing CoNi ferromagnetic thin film on the film (sample) and vacuum under similar conditions as above. A CjoN magnetic thin film (sample B) containing no oxygen without introducing oxygen gas was prepared at a temperature of 5×10 Torr. As a result of measuring the amount of oxygen in the film mainly using Auger rod spectroscopy, it was found that the average amount of oxygen in the film of sample A was 10% in terms of atomic ratio (...+F, X100) to Go and Ni. That of B was less than 1%. A rust preventive agent mainly composed of phenol ethers was applied to the surface of these samples using ethyl alcohol and
After dissolving in acetone, toluene, etc. and coating and drying (coating amount was adjusted to 10 to 100 mg/rn3), it was left in an atmosphere of 50 °C and 90 °C R, H, and periodically removed during this period. The state of rust formation was investigated by microscopic observation. The results are shown in the table below.

As is clear from the table, the rust preventive agent containing phenol ethers as a main component had a great rust preventive effect on the CoNi thin film containing oxygen. This effect is due to Co
The same is true for Ni thin films (Ni 10-55 wt%),
GO thin film, FeNi thin film, Fe-G.

Similar results were observed in thin films and the like.

In addition, for the untreated products without rust prevention, rust occurred within one week for both Samples A and B.

As explained above, according to the present invention, corrosion resistance in high humidity can be easily improved.

Claims (1)

[Claims] A magnetic recording medium characterized in that a ferromagnetic metal thin film containing oxygen is formed on a nonmagnetic substrate, and a rust preventive agent containing phenol ethers as a main component is adhered to the ferromagnetic metal thin film.