JPS6089815A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having improved corrosion resistance even under high humidity by forming a thin ferromagnetic metallic film contg. oxygen on a nonmagnetic base plate and sticking a rust preventive agent which consists essentially of a compd. having an SH group and is added with Al ion to said film. CONSTITUTION:A thin ferromagnetic film consisting essentially of a metal such as Fe, Ni Co or the like or the alloy thereof and contg. oxygen is formed by a vacuum deposition, sputtering method, etc. on a non-magnetic base plate consisting of polyester, polyimide film, Al plate, etc. A coating liquid of alcohol, etc. which consists essentially of a rust preventive agent such as a compd. having an SH group, for example, benzothiazole, sodium thioglycolate, etc. and is incorporated with a small amt. of naphthol, hydroquinone according to need and further a small amt. of Al ion is coated on the thin ferromagnetic film and is dried to form a protective film. The magnetic recording medium having excellent corrosion resistance is thus obtd.

Description

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

(Conventional structure and its problems) Plastic films such as polyester and polyimide, and non-magnetic materials such as aluminum plates and glass plates are deposited on the surface of a molded substrate by vapor deposition, ion blating, sputtering, etc. in a vacuum. )Fe, Ni.

A magnetic recording medium in which a ferromagnetic thin film containing oxygen is formed mainly from Co or an alloy thereof is suitable for high-density recording such as video signal recording, but when the thickness of the ferromagnetic metal thin film is 0.05 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 deteriorates practical properties such as spacing 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 contains oxygen, that is, it is partially oxidized, Fe is also a material that exhibits a rust prevention effect.
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, so new anti-corrosion agents have been developed. It became necessary to find something compatible with ferromagnetic metal thin films containing oxygen.

(Object of the invention) The present invention has been made in view of the drawbacks of the above-mentioned conventional examples, and
This is a new product that is compatible with ferromagnetic metal thin films containing oxygen.

(Structure of the Invention) In order to achieve the above object, 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 compound having a mercapto group is added to the ferromagnetic metal thin film. A rust preventive agent containing aluminum ions as a product is attached.

(Description of Examples) The magnetic recording medium according to the present invention is configured as follows.

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, and inorganic plates such as glass plates are used, and the presence of a trace amount of oxygen gas is applied directly or through a non-magnetic thin film layer on these. It is made of diagonal or vertical columnar crystals with a thickness of 0.05~0 using methods such as vapor deposition, sputtering, and ion plating in a vacuum.
．． 5 μm Co, Fe.

Fe-Ni, Co-Ni, Fe-Co, Fe-N
Forming a single or multilayer ferromagnetic thin film mainly composed of i-Co etc. and containing 3 to 45% oxygen in atomic ratio to the magnetic metal, and producing a compound having a mercapto group on the surface of this ferromagnetic thin film. In addition, a rust preventive agent containing aluminum ions is applied.

Here, examples of the compound having a mercapto group in the present invention include 2-medulecaptopenzothiazole, benzothiazole, 2-methylbenzothiazole, benzothiazoline, and thioglycolic acid. The rust preventive agent in the present invention mainly contains these substances alone or a mixture of two or more thereof (preferably at least 80% or more), and optionally contains organic compounds other than compounds having a mercapto group, such as It contains small amounts of naphthols, hydroquinones, acetophenones, quinones, etc., and also contains a small amount of aluminum ions.

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 0 per magnetic recording medium im3
It is about 5 to 500 mg.

□A method in which the magnetic recording medium is mixed with a ferromagnetic material, diluted with a solvent if necessary, and applied to the surface of the ferromagnetic thin film, a method in which rust preventive vapor is applied to the surface of the ferromagnetic thin film; In some cases, known means may be used, such as a method in which the ferromagnetic thin film is transferred onto the surface of the ferromagnetic thin film by having the ferromagnetic film be present on the back surface of the ferromagnetic thin film when the tape is wound thereon. Mani,
It is also possible to use ordinary lubricants, antistatic agents, and other additives together with the rust preventive agent.

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

A polyester film with a thickness of 10 μm was spread over the circumferential surface of a cylindrical can, and CoNi was melted by electron beam heating by introducing oxygen gas at a rate of 0.31/a in a vacuum of 5 × 10-' Torr. Alloy (Ni content 20wt%
) was continuously obliquely evaporated (low incidence angle component 3o0, cut below), and a 1000 mm thick oxygen-containing CoNi ferromagnetic thin film was formed on the film (sample A) under vacuum conditions similar to the above. A sample (sample B) was prepared in which a CoNi ferromagnetic thin film containing no oxygen was formed at 5×10''-6 Torr without introducing oxygen gas.

As a result of measuring the amount of oxygen in the film mainly using Auger electron spectroscopy, the average amount of oxygen in the film of sample A was C.

and the atomic ratio to Ni (-'-x too io at 5
% of Co+Ni, and that of sample B was less than 1%. Various types of rust preventive agents containing mercapto group-containing compounds and aluminum ions are dissolved in ethyl alcohol, acetone, toluene, etc., and then applied and dried (coating amount is 10 to 100 mg/m3) on the surface of these samples. (adjusted to 50℃).

The specimens were left in an atmosphere of 90% R, H, and during this period they were periodically taken out and observed under a microscope to examine the state of rust formation. The results are shown in the table below.

As is clear from the table, the rust preventive agent containing mercapto group-containing compounds and aluminum ions is
It was highly effective in preventing rust on CoNi thin films containing oxygen.

This effect is due to the CoNi thin film (N
i 10 to 55 wt%), the same is true, Co thin film, F
Similar results were observed in eNi thin films, Fe-Co thin films, and the like.

In addition, if no rust prevention treatment is applied, both samples A and B are 1
Rust developed within a week.

(Effects of the Invention) As explained above, 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 compound having a mercapto group is used as a main component in the ferromagnetic metal thin film. By adhering a rust preventive agent containing aluminum ions, corrosion resistance under high humidity can be significantly improved.

Patent applicant: Matsushita Electric Industrial Co., Ltd. Agent Koji Hoshino

Claims (1)

[Claims] Magnetic recording characterized in that a ferromagnetic metal thin film containing oxygen is formed on a nonmagnetic substrate, and a rust preventive agent containing a compound having a mercapto group as a main component and aluminum ions added thereto is adhered to the ferromagnetic metal thin film. Medium.