JPS58194139A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance of a magnetic recording medium at high humidity by sticking a corrosion inhibitor contg. aromatic amine having a phenolic hydroxyl group as the principal component to the ferromagnetic metallic thin film contg. oxygen formed on the nonmagnetic substrate. CONSTITUTION:A polyester film, an Al plate or the like is used as a nonmagnetic substrate. A single-layer or multilayered ferromagnetic thin film of Co, Fe 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 the substrate directly or with a nonmagnetic thin film in-between by vapor deposition, sputtering or other method in vacuum contg. a very small amount of gaseous oxygen. A corrosion inhibitor contg. aromatic amine having a phenolic hydroxyl group as the principal component is applied to the ferromagnetic thin film. The inhibitor is allowed to exist on the surface of the thin film, in the interior, or in contact with the interface between the thin film and the base under the film.

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 nonmagnetic layer such as an aluminum plate or a glass plate, by vapor deposition, ion plating, sputtering, etc. in a vacuum.

A magnetic recording medium in which a ferromagnetic thin film containing oxygen is formed entirely based on CO or an alloy thereof is suitable for high-density recording such as video signal recording, but if the thickness of the ferromagnetic metal thin film is zero Because it is small at 0.05 to 0.6 μm, it is easy to cause corrosion on the surface if it is left in high humidity, especially in an environment where temperature changes and large dew condensation may occur.
When the corrosion progresses to a certain extent, it affects electromagnetic conversion characteristics and deteriorates practical properties such as Heradouch% wear resistance.
・Because 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 magnetic layers, there was a desire for a rust preventive agent that would be sufficiently effective with just a few molecules of adhesion or adsorption. . Ferromagnetic thin films made entirely of Fe, Ni, Go, or their alloys and containing oxygen have higher coercive force and superior corrosion resistance than thin films made of pure metals. Materials that exhibit a rust-preventing effect because they are contained, that is, partially oxidized - Rust preventive agents - Known materials used for bulk metals such as Fe, Go, and Ni are not necessarily suitable. However, when these rust preventives are actually applied, they may actually accelerate corrosion, so it is necessary to find a new one that is compatible with ferromagnetic thin films containing oxygen. As a result of various studies, the inventors of the present invention have found that an aromatic amine having a phenolic hydroxyl group is suitable as a rust preventive agent for ferromagnetic thin films containing oxygen. 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 an aromatic amine having a phenolic hydroxyl group as a main component is applied to the ferromagnetic metal thin film. It is characterized by the fact that it is attached.

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 plates 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 made of diagonal or vertical columnar crystals using methods such as
Go from 6 to 0.6 μm.

Fe, Fe-Ni, Go-Ni, Fe-G
An aromatic material having a phenolic hydroxyl group is formed by forming a single-layer or multi-layer ferromagnetic thin film consisting mainly of O, Fe-Ni-C (, etc.) and containing oxygen in an atomic ratio of 3 to 46% with respect to the magnetic metal. Apply a rust inhibitor based on group amines.

The aromatic amine having a phenolic hydroxyl group in the present invention includes 2-aminonaphthol, diaminophenol,
There are 0-amine phenols and the like.

1) The rust preventive agent in the present invention is composed of a single substance or a mixture of two or more of these, and contains at least 80% or more). If necessary, an organic compound other than an aromatic amine having a phenolic hydroxyl group. For example, hydroquinones,
It contains small amounts of oxidium compounds, chelon, acetophenones, quinones, etc.

These rust inhibitors are applied to at least the surface of the 5 ferromagnetic thin film.

If possible, C should be present inside or in contact with the interface with the substrate on which the ferromagnetic thin film is formed.
and its full effect is demonstrated. The sensitivity is about vO56 to 6o01 ng per 1rT'1'' of magnetic recording medium.Specifically, the presence of the rust preventive agent is made by mixing it with itself or with a substance capable of forming a film such as a polymer compound. If necessary, dilute it with a solvent and apply it to the surface of the ferromagnetic thin film while the magnetic recording medium is in the form of a tape. Known means can be used, such as leaving the tape present so that it is transferred to the surface of the ferromagnetic thin film when the tape is rolled up.Additionally, along with the rust preventive agent, ordinary lubricants, antistatic agents, etc. may be added. It is also possible to use agents.

Next, an example of the present invention will be specifically explained.〇Thickness 1
A 0 μm polyester film was placed along the circumferential surface of a 1 m circular can, and oxygen gas was introduced at a rate of 0.31/m in a vacuum of 6 × 10 −5 Torr, and the GoNi alloy was melted by electron beam heating. Similar to the above, a 1000-thick oxygen-containing CoNi ferromagnetic thin film (sample) was formed by continuous oblique evaporation (low incidence angle component 3001d bottom cut) of nickel (Ni content 20 wt%). A sample (Sample B) was prepared in which a CoNi ferromagnetic thin film containing no oxygen was completely formed under the following conditions at a vacuum level of 6×10” Torr and 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 sample A
The average amount of oxygen in the film is the atomic ratio of CO to Ni (.

oo, X100) is 10%, and that of sample B is 19
A rust preventive agent mainly composed of aromatic amines having phenolic hydroxyl groups was dissolved in total ethyl alcohol, acetone, toluene, etc. and applied and dried (coating amount was 10 to 100%). /rT11) After that, it was left in an atmosphere at 60°C, 190% R, H, and during that period, it was periodically taken out and observed under a microscope to examine the state of rust occurrence. The results are shown in the table below.

Table J: As is clear, the rust inhibitor whose main component is an aromatic amine having a phenolic hydroxyl group is
-The rust resistance was 6 times higher than that of the Ni thin film.

This effect is similar for Go-Ni4 films containing *3 to 46% oxygen (10 to 55 wt% Ni), and C.

It was similar in thin films, Fe-Ni thin films, Fe-Go thin films, etc.

In addition, both samples A and B are untreated products that are not treated with rust-preventive metals.
Rust appeared within a week.

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

Name of agent: Patent attorney Toshio Nakao and 1 other person 20
7-

Claims (1)

[Claims] A magnetic material characterized by forming a ferromagnetic metal thin film containing oxygen on a non-magnetic substrate, and adhering to the ferromagnetic metal thin film a rust preventive agent whose main component is an aromatic amine having a phenol hydroxide group. recoding media.