JPS58194133A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance at high humidity by applying a corrosion inhibitor contg. a compound having one or more phenolic hydroxyl groups and a heterocyclic ring contg. one or more nitrogen atoms as the principal component to the ferromagnetic thin film contg. oxygen. CONSTITUTION:A single-layer or multilayered ferromagnetic thin film of Co, Fe, Fe-Ni, Co-Ni, Fe-Co, Fe-Ni-Co or the like contg. oxygen by 3-45 atomic% of the amount of the magnetic metal, consisting of diagonal or vertical prismatic crystals, and having 0.05-0.5mum thickness is formed on a nonmagnetic substrate directly or with a nonmagnetic thin film in-between by vapor deposition, sputtering, ionic plating or other method in vacuum contg. a very small amount of gaseous oxygen. The ferromagnetic thin film is coated with a corrosion inhibitor contg. a compound having one or more, phenolic hydroxyl groups and a heterocyclic ring contg. one or more nitrogen atoms as the principal component. The compound is 4-(2-pyridylazo)-resorcin, 1-(2-pyridylazo)-2-naphthol, 4-quinolinol, quinolinediol or the like.

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 and Ni are deposited on 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 mainly composed of Go or an alloy thereof and containing oxygen is suitable for high-density recording such as video signal recording. Because it is small at ~0.5 μm, it is easy to corrode the surface if left in high humidity, especially in an environment where temperature changes are large and condensation occurs, and if this corrosion progresses to a certain extent, it will affect the electromagnetic conversion characteristics. It also causes deterioration of practical properties such as helad touch and abrasion resistance.

When suppressing this corrosion with a rust preventive agent, there are strict limits on the thickness of the protective film that can be formed on the surface of the magnetic layer due to spacing loss between the head and the magnetic layer, so only a few molecules of adhesion or adsorption can occur. A sufficiently effective rust preventive agent was desired. F
A ferromagnetic thin film mainly composed of e, Ni, Go, or an alloy thereof and containing oxygen has a higher coercive force than a thin film made of these pure metals.

It has excellent corrosion resistance, but because it contains oxygen, that is, it is partially oxidized, materials that exhibit a rust preventive effect (rust preventive agents) are also inferior to Fe, Go, etc. Known anti-corrosion agents used for bulk metals are not necessarily suitable, and in fact, when used as anti-corrosion agents, they may actually accelerate corrosion. It became necessary to find something compatible with ferromagnetic thin films.

As a result of various studies conducted by the present inventors, the present inventors found that a compound containing a heterocyclic ring containing one or more nitrogen atoms and a phenolic hydroxyl group as a main component is used as a rust preventive agent for ferromagnetic thin films containing oxygen. I found something suitable.

That is, 1 the present invention is a magnetic recording medium in which a ferromagnetic metal thin film containing oxygen is formed on a non-magnetic substrate, characterized in that a rust preventive agent containing the above compound as a main component is attached to the ferromagnetic metal thin film. That is.

Polyester film is used as a non-magnetic substrate.

Plastic films such as polyimide films.

Metal plates such as aluminum plates and stainless steel plates, inorganic plates such as glass plates, etc. are used, and evaporation is performed on these directly or through a non-magnetic thin film layer in a vacuum in the presence of a trace amount of oxygen gas. , 0.0 thickness consisting of diagonal or vertical columnar crystals by methods such as Su Kuta 5 ion brating.
5-0.5 μm Go, Fe.

ye-Ni, Go-Ni, Fe-Co,
A heterocyclic ring containing one or more nitrogen atoms is formed on a single-layer or multi-layer ferromagnetic thin film mainly composed of ye-Ni-co, etc., containing 3 to 45% oxygen in atomic ratio to the magnetic metal. A rust preventive agent whose main component is a compound having a phenolic hydroxyl group is applied.

having a heterocycle containing one or more nitrogen atoms in the present invention,
And, the compound having a phenolic hydroxyl group is 4-(
2-pyridylazo)resorcin.

1-(2-pyridylazo)-2-naphthol, 4-quinolol, 4-methyl-2-quinolitool.

Examples include 8-quinolitool, quinoline diol, and kynurenic acid.

The rust preventive agent of the present invention contains at least 80% or more of these alone or a mixture of two or more of them), and optionally has a heterocycle containing one or more nitrogen atoms, and , organic compounds other than compounds having a phenolic hydroxyl group, for example.

It contains small amounts of hydroquinones, acetophenones, quinones, etc.

These rust inhibitors are applied to at least the surface of the ferromagnetic thin film.

If possible, the effect can be exerted by making it exist inside or in contact with the interface with the base on which the ferromagnetic thin film is formed. The appropriate amount is about 0.6 to 60 Qη per 1 m1 of the 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. There is a method in which rust preventive vapor is applied to the surface of the ferromagnetic thin film, and if the magnetic recording medium is in the form of a tape, it is placed on the back side of the tape and transferred to the surface of the ferromagnetic thin film when the tape is rolled up. How to do it.

Well-known means such as the following 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.

Oxygen gas was applied to a polyester film with a thickness of 1 μm along the circumferential surface of the cylindrical can at a vacuum level of 5×10 TOrr. CoNi alloy (Ni-containing -14:20
wt%) was continuously obliquely deposited (cutting the low incident angle component below 30°), and a 1000% thick oxygen-containing C0Ni ferromagnetic thin film was formed on the film (sample) under similar conditions as above. Vacuum degree 6X 1 o-'Torr,
A sample (Sample B) was prepared in which a CoNi ferromagnetic thin film containing no oxygen was formed without introducing oxygen gas. As a result of measuring the amount of oxygen in the film mainly using Auger electron spectroscopy, it was found that the average amount of oxygen in the film of each sample had an atomic ratio of 1% or less to Co and N1. A rust preventive agent containing a compound having a heterocyclic ring containing one or more nitrogen atoms and a phenolic hydroxyl group as a main component is dissolved in ethyl alcohol, acetone, toluene, etc. on the surface of these samples, and then applied and dried (applied). (The amount was adjusted so that it was 10 to 1 o ”/static.) After 17 days, it was left in an atmosphere at 60°C and 90% R1H, and during that time, it was periodically taken out and observed under a microscope to check the state of rust formation. The results are shown in the table below.

As is clear from the table, rust inhibitors whose main component is a compound having a heterocycle containing one or more nitrogen atoms and a phenolic hydroxyl group have a large rust preventive effect on coNi thin films containing oxygen. Ta. This effect is due to c
The same was true for the Oy1 thin film (Ni 10-55 wt%), and it was also similar for the Co thin film, FθN1 thin film, Fe-Co thin film, etc.

In addition, for untreated products without rust prevention, both samples A and B are %
Rust appeared within a week.

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

Claims (1)

[Claims] A ferromagnetic metal thin film containing oxygen is formed on a non-magnetic substrate, and a rust preventive agent whose main component is a compound having a heterocycle containing one or more nitrogen atoms and a phenolic hydroxyl group is attached to the ferromagnetic metal thin film. A magnetic recording medium characterized by: