JPS58194137A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To easily improve the corrosion resistance of a magnetic recording medium at high humidity by allowing an aromatic nitrile compound having bonded fluorine to exist in the magnetic layer of the medium made of a ferromagnetic metallic thin film of Co or a Co alloy. CONSTITUTION:An aromatic nitrile compound having bonded fluorine is allowed to exist in the magnetic layer of a magnetic recording medium made of a ferromagnetic metallic thin film of Co or a Co alloy to produce the effect. The compound is allowed to exist at least on the surface of the thin film, in the interior if possible, or in contact with the interface between the thin film and the base under the film. The proper amount of the compound is about 0.5- 500mg per 1m<2> magnetic recording medium. The compound is pentafluorophenylacetonitrile, C6H5CH2CN, tetrafluoroterephthalonitrile, C6F4(CN)2 or 2-(trifluoromethyl)benzonitrile.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium with excellent corrosion resistance.

Vacuum deposition and sputtering of thin films of iron, cobalt, nickel, or alloys containing these as main ingredients.

Metal thin film type magnetic recording tapes formed on a substrate film by methods such as ion blating or plating, or metal powder type magnetic recording tapes in which these metal powders are bonded with a resin binder, are made mainly of conventional iron oxide. Unlike ordinary coating-type Qi/, which combines ferromagnetic powder with a resin binder, it is susceptible to corrosion in high humidity or corrosive gases.

For this reason, the surface of thin metal film or metal powder magnetic recording tapes is stabilized by oxidation using glow discharge or anti-corrosion treatments such as extremely thin resin coatings, but these are not in a state that is sufficiently satisfactory for practical use. The current situation is that it is difficult to obtain things.

Many regions in our country have a rainy season.

During this period, the conditions are extremely hot and humid from the perspective of metal corrosion, and in fact, there is a tendency for many complaints about corrosion of various metal parts to occur during this period.

Furthermore, our country is surrounded by the sea, and residents near the coast are constantly exposed to a highly corrosive atmosphere containing salt. Furthermore, our country is a volcanic country, with hot springs and volcanic gases occurring in many areas.

In such areas, hydrogen sulfide (H2S)
.

It generates corrosive gases such as sulfur dioxide (SO2) and ammonia (NH5). Additionally, many regions have industrial zones, some of which generate various corrosive gases and dust.

As is well known, iron corrodes even under normal environments, while nickel and cobalt have superior corrosion resistance compared to iron, but corrode under the aforementioned environments. Especially unlike metal plates, vacuum evaporation, sputtering, and ion blating.

Metal thin films made by methods such as Sabagane are generally more active than metal plates and tend to be more susceptible to corrosion.

Magnetically recorded cassette tapes, whether audio or video recording, must be able to be stored for a long period of time without corrosion or deterioration. For example, for long-term recording of images of human childhood, corrosion resistance of 10 to 20 years will be required.

Vacuum-deposited tapes are made by applying iron, nickel, cobalt, or their alloys using a vacuum deposition method.

If left in various atmospheres, it may corrode in a relatively short period of time. For example, corrosion may occur in a few weeks in an atmosphere of 50 to 60 °C + 90% relative humidity, and white speck-like corrosion products may be observed in a few months even if the product is left indoors during the rainy season. There is. In order to prevent such deterioration due to corrosion, the surface layer is oxidized by glow discharge or coated, but it is still difficult to completely guarantee corrosion resistance for an extremely long period of time.

The present invention provides an aromatic nitrile compound with fluorine bonded to the magnetic layer of a magnetic recording medium made of a ferromagnetic metal thin film of cobalt metal or cobalt alloy, at least on the surface of the ferromagnetic thin film if possible, or inside the ferromagnetic thin film. By making it exist in contact with the interface with the base on which it is formed, its effect is exhibited. The appropriate amount is about 0.5 to 500 mq per m2 of magnetic recording medium.

The fluorine-bonded aromatic compound used in the examples of the present invention is as follows.

■ Pentafluorophenylacetonitrile C, 6H5
0H2CM ■ Tetrafluoroterephthalonitrile 06F4 (CN
)2 ■ 2-()lifluoromethyl)benzonitrile 2- CF306H4ON ■ 3-()lifluoromethyl)benzonitrile 3- OF, 06H4ON ■ 4-()lifluoromethyl)benzonitrile 4- CF306H4ON @ 2-( Trifluoromethyl)phenylacetonitrile 2- CF306H40HCN ■ 3-()lifluoromethyl)phenylacetonitrile 3- CF306H40HCN ■ 4-()lifluoromethyl)phenylacetonitrile 4- CF3C6H4CH20N ■ Pentafluorobenzonitrile 6F5ON Specific method of existence Methods include applying the above-mentioned compounds by themselves or in a mixture with a substance capable of forming a film such as a polymer compound, diluting it with a fluorocarbon solvent if necessary, to the surface of a ferromagnetic thin film, or applying the vapor of these compounds. A method of applying the magnetic recording medium to the surface of the ferromagnetic thin film, and a method of making the magnetic recording medium exist on the back side of the tape and transferring it to the surface of the ferromagnetic thin film when the tape is wound. can be used.

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

A Colt alloy (Ni content: 20 wt. %)
An oxygen-containing CoNi ferromagnetic thin film with a thickness of 1,000 mm was formed on the film by continuous oblique evaporation (cutting the low incident angle component below 30°) (sample), and the film was evaporated under vacuum degree 5 under similar conditions to the above. x 10 Torr, an OoN i ferromagnetic thin film containing no oxygen was prepared 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 amount of oxygen in the film of the sample was determined by the atomic ratio (
oO+Ni×1oo) was 10%, and sample B (7) was less than 1%. Each of the above-mentioned compounds was individually dissolved in a fluorocarbon-based solvent and coated and dried on the surface of these samples (coating amount: 10-10%).

Tnq/ca) After 50℃, relative humidity 9
The specimen was left in a 0% atmosphere and periodically taken out and observed under an optical microscope to examine the state of corrosion.

As a result, relatively large corrosion was observed in the untreated sample after 2 weeks, but almost no corrosion was observed in the treated sample even after 6 weeks.

In sample B, large corrosion occurred within one week in the untreated sample, but no corrosion that would cause a practical problem was observed in the treated sample even after 6 weeks.

The reason why the corrosion resistance is greatly improved by the present invention is that the inclusion of fluorine in the molecule improves water repellency, and the large reactivity of the cyan group-C3N causes the bonding with cobalt and nickel to eliminate the starting point of corrosion. This is thought to be due to

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

Claims (1)

[Claims] A magnetic recording medium characterized in that a ferromagnetic metal thin film containing oxygen is formed on a nonmagnetic substrate, and an aromatic nitrile compound to which fluorine is bonded is adhered to the ferromagnetic metal thin film.