JPS58194135A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance at high humidity by applying a corrosion inhibitor contg. a heterocyclic compound 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 geseous oxygen. The ferromagnetic thin film is coated with a corrosion inhibitor contg. a heterocyclic compound contg. one or more nitrogen atoms as the principal component. The heterocyclic compound is acridine, 2,2',2''- terpyridyl, neocuproine, 2,2'-dipyridyl, benzotriazole, 5-methylbenzotriazole, p-phenanthroline, 1,10-phenanthroline, aldehydecollidine, benzylpyridine, phenylpyridine, quinazoline 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.

Magnetic recording media, in which an ion-preferromagnetic thin film is formed by vapor deposition in vacuum on the surface of a substrate made of a plastic film such as polyester or polymide, or a non-magnetic material such as an aluminum plate or glass plate, can be used for high-speed recording such as video signal recording. It is suitable for density recording, but the thickness of the ferromagnetic metal thin film is O,
,05~0.5μm, so if it is left in high humidity, especially in an environment where temperature changes are large and condensation occurs, the surface tends to corrode, and if the corrosion progresses to a certain extent, the electromagnetic conversion characteristics will deteriorate. It also affects 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. A sufficiently effective rust preventive agent was desired. F
Ferromagnetic thin films that are mainly made of E, Ni, Co, or their alloys and contain oxygen have higher coercive force and superior corrosion resistance than thin films made of pure metals. Because it is partially oxidized, the material that exhibits the rust preventive effect - the rust preventive - also contains Fe,
Known anti-corrosion agents used for bulk metals such as Co and Ni are not necessarily suitable, and when 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 inventors of the present invention have found that a substance whose main component is a heterocyclic compound containing one or more nitrogen atoms 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 the ferromagnetic metal thin film is coated with a barrier whose main component is a heterocyclic compound containing one or more nitrogen atoms. It is characterized by having a rust agent adhered to it.

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 or sputtering is performed on these plates directly or through a non-magnetic thin film layer in a vacuum in the presence of a trace amount of oxygen gas. , thickness O, O6 ~ consisting of oblique or vertical columnar crystals by methods such as ion blating
0.5 μm Co, Fe.

Fe-Ni, Co-Ni, Fe-Co, F
Mainly composed of e-Ni-Co, etc., and contains 3 to 45% oxygen in atomic ratio to magnetic metal! A rust preventive agent whose main component is a heterocyclic compound containing one or more nitrogen atoms is applied to the It layer or multilayer ferromagnetic thin film formed thereon.

In the present invention, the heterocyclic compound containing one or more nitrogen atoms includes acridine, 2,2',2''-te/l/
HiIJdyl, neocuproine, 2,2'-dipyridyl,
Benzotriazole, 6-methylbenzotriazole,
Batophenanthroline, 1. , 10-phenanthroline, aldehyde collidine, benzylpyridine, phenylpyridine, quinazoline, 2-heptadecyl imidazole,
etc.

The rust preventive agent in the present invention mainly contains these 11 substances or a mixture of two or more of them, and contains at least 80% of them). It contains small amounts of compounds such as cuperone, acetophenones, and quinones.

These anti-corrosion agents exert 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 1 m of magnetic recording medium.
It is about 0.5 to 500,771 g per serving. 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. Well-known means such as the method described below 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 ttm was placed along the circumferential surface of a cylindrical can, and oxygen gas was introduced at a rate of 0.3 ff/- in a vacuum of 5 x 1 O-5 Torr, and a CoNi alloy (CoNi alloy) was melted by electron beam heating. Ni content 20
(Sample A) in which an oxygen-containing CoNi ferromagnetic thin film with a thickness of 100X was formed on the film by continuous oblique evaporation (cutting the low incident angle component below 30') of
A CoNi ferromagnetic thin film containing no oxygen was prepared under conditions similar to those described in Section 2 at a vacuum level of 5×10' Torr and without introducing oxygen gas (sample B). As a result of measuring the amount of oxygen in the film mainly using Auger electron spectroscopy,
The average concentration in the film of sample A is 10%, and that of sample B is 1
It was less than 1.

A rust preventive agent whose main component is a heterocyclic compound containing one or more nitrogen atoms is dissolved in ethyl alcohol, acetone, toluene, etc., and applied and dried on the surface of these samples (coating amount: 10 to 1
It was adjusted so that it became oomy/"". ) then 50
1:, 90° R, H, and was left in an atmosphere, during which time the state of rust formation was examined by periodically taking it out and observing it with a microscope. The results are shown in the table.

As is clear from the margin table below, the rust inhibitor whose main component is a heterocyclic compound containing one or more nitrogen atoms is Co Ni containing oxygen.
It was highly effective in preventing rust compared to thin films. This effect is due to the CoNi thin film with oxygen content of 3 to 46% (Njlo-55wt%).
The same is true for CO thin film, FeNi thin film, Fe-Co thin film.
Similar results were observed in thin films and the like.

In addition, in the untreated sample A and B, rust occurred within one 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 heterocyclic compound containing one or more nitrogen atoms is attached to the ferromagnetic metal thin film. magnetic recording media.