JPS59142743A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium adhered with a rust inhibitor adapted to a thin ferromagnetic film by adhering the rust inhibitor consisting essentially of a monocarboxylic acid and sodium nitrite on the thin ferromagnetic metallic film. CONSTITUTION:A thin ferromagnetic film of a single or multiple layers consisting essentially of Co, Fe, Fe-Ni, Co-Ni, Fe-Co, Fe-Ni-Co, etc. having 0.05-0.5mum thickness and contg. 3-45% oxygen in the atomic ratio with a magnetic metal is formed on a non-magnetic base plate, and a rust inhibitor consisting essentially of monocarboxylic acid and sodium nitrite is adhered thereon. The monocarboxylic acid refers to a benzoic acid, methyl benzoic acid, P-isopropyl benzoic acid, etc. The rust inhibitor consists essentially of a mixture composed of the monocarboxylic acid and sodium nitrite (preferably >=60% is incorporated) and is added with a small amt. of org. compds. except the monocarboxylic acid and the sodium nitrite, for example, naphthol, hydroquinone, acetophenon, quinone, etc.

Description

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

Structure of the conventional example and its problems Appe 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 mainly composed of Ni, Go, or an alloy thereof and containing oxygen is formed is suitable for high-density recording such as video signal recording, but if the thickness of the ferromagnetic metal thin film is , 05 to 0.5 μm, so if it is left in high humidity environments, especially in environments where temperature changes are strong 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 causes deterioration of practical properties such as head touch and abrasion resistance. When suppressing this corrosion with a rust preventive agent, the head
Due to the spacing loss between the magnetic layers, there are strict limits on the thickness of the protective film that can be formed on the surface of the magnetic layer, so there was a need for a rust preventive agent that would be sufficiently effective with adsorption, even if only a few molecular layers were attached. . Ferromagnetic thin films that are mainly made of Fe, Ni, co, or their alloys and contain oxygen have higher coercive force and superior corrosion resistance than thin films made of pure metals. , that is, partially oxidized, Fa, Go,
Known rust inhibitors used for metals such as Ni (
Materials that exhibit a rust-preventing effect are not necessarily suitable, and when these rust preventives are actually applied, they may actually accelerate corrosion. It became necessary to find something suitable.

OBJECTS OF THE INVENTION The present inventor provides a magnetic recording medium in which a rust preventive agent suitable for a ferromagnetic thin film as described above is attached.

Structure of the Invention As a result of various studies, the present inventors have found that a substance containing monocarboxylic acid and sodium nitrite as main components 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 nonmagnetic substrate.
It is characterized in that a rust preventive agent containing monocarboxylic acid and sodium nitrite as main components is attached to the ferromagnetic metal thin film.

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 are used, and evaporation is performed on these plates either directly or through a non-magnetic thin film layer in a vacuum in the presence of a trace amount of oxygen gas.

Go, Fe, Fe-Ni, Co-Ni, F with a thickness of 0.05 to 0.5 μm consisting of oblique or vertical columnar crystals by sputtering, ion blating, etc.
e-Co.

Monocarboxylic acid, sodium nitrite, and lithium are used to form a single-layer or multilayer ferromagnetic thin film that is mainly composed of Fe-Ni-Go, etc., and contains oxygen at an atomic ratio of 3 to 46% with respect to the magnetic metal. Apply a rust preventive agent containing as the main ingredient.

DESCRIPTION OF EXAMPLES The monocarboxylic acids according to the present invention are benzoic acid, methylbenzoic acid, ethylbenzoic acid, P-impropylbenzoic acid, and 2,3-dimethylbenzoic acid.

Examples include 2.4-dimethylbenzoic acid, 2.5-dimethylbenzoic acid, 35-dimethylbenzoic acid, and 2.4.5-trimethylbenzoic acid. The rust preventive agent in the present invention is mainly a mixture of a monocarboxylic acid type and sodium nitrite (preferably containing Co% or more), and if necessary, an organic compound other than the monocarboxylic acid type and sodium nitrite. Compounds such as naphthols, hydroquinones, acetophenones.

It is made by adding a small amount of quinones, etc.

These rust preventive 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 500 s to 1 m' 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. 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, specific examples of the present invention will be described.

A 10 μm thick polyester film was placed along the circumferential surface of a cylindrical can, and oxygen gas was introduced at a rate of 0.3 t/wn in a vacuum of 5 x 1 c) Torr, and a Co Ni alloy was melted by electron beam heating. (Ni content 20wt%) was continuously obliquely deposited (cutting the low incident angle component below 30'') to form oxygen-containing CoNi with a thickness of 1QoOx.
A ferromagnetic thin film formed on a film (sample A)
) and vacuum level 5×1O-6 Torr under similar conditions as above.
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, the average amount of oxygen in the film of sample A was 10% at an atomic ratio of Co and N1 of ○ (-111 菟100). Go of sample B
+N1 It was less than 1%. On the surface of these samples, apply a rust preventive agent mainly composed of monocarboxylic acid and nitrous acid dissolved in ethyl alcohol, acetone, toluene, etc. (coating amount is 10 to 100 μ/d). The specimen was then left in an atmosphere of 50° C. and 90% R, H, during which time the specimen was periodically taken out and observed under a microscope to examine the state of rust formation. The results are shown in the table below.

(Hereinafter referred to as "all white") From this result, for sample B, no such result was observed for any monocarboxylic acid type and sodium nitrite. For human samples, benzoic acid, methylbenzoic acid, and ethylbenzoic acid.

(Both added sodium nitrite), no rust occurred even after 5 weeks. Still, P-isopropylbenzoic acid, 2
．． 3-dimethylbenzoic acid, 2,4-dimethylbenzoic acid,
2.5-Dimethylbenzoic acid.

3.5-dimethylbenzoic acid, 2,4.5-)dimethylbenzoic acid showed no rust formation for up to 4 weeks, and although some rust occurred after 5 weeks, sufficient rust prevention effect was observed. was completed.

Effects of the Invention As described above, according to the present invention, an excellent antirust effect of a ferromagnetic metal thin film containing oxygen can be obtained.

Claims (1)

[Claims] A magnetic device characterized in that a ferromagnetic metal thin film containing oxygen is formed on a non-magnetic substrate, and a rust preventive agent containing monocarboxylic acid and sodium nitrite as main components is adhered to the ferromagnetic metal thin film. recoding media.