JPH07101494B2 - Metal thin film magnetic recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a metal thin film type magnetic recording medium having improved durability at high temperatures.

Conventional Configuration and Problems Thereof In recent years, a metal thin film type magnetic recording medium has attracted attention as a high density magnetic recording medium and is gradually being put into practical use.

The conventional metal thin film type magnetic recording medium will be described below.

FIG. 1 is a sectional view of a conventional metal thin film magnetic recording medium, in which 1 is a substrate and 2 is a magnetic layer. The electromagnetic conversion characteristics of the metal thin film magnetic recording medium are much better than those of the coating type magnetic recording medium which has been used conventionally and the oxide thin film magnetic recording medium which has been used in recent years. It is known to show. However, it is said that the metal thin film magnetic recording medium has a difficulty in practical durability as compared with the conventional coating type magnetic recording medium and the oxide thin film magnetic recording medium, and improvement of the durability is an issue. Although the durability varies in various environments, one of the conditions that are particularly problematic for the metal thin film magnetic recording medium is the durability at a high temperature of 50 ° C. or higher, for example. The durability at high temperature is inferior to the durability in other environments, probably because the emissivity of the magnetic surface side of the metal thin film magnetic recording medium is low, so that the cooling effect at high temperature is Since it is inferior to the medium and the oxide thin film magnetic recording medium, it is considered that the temperature on the magnetic surface side rises and the durability deteriorates.

In the conventional metal thin film type magnetic recording medium, the magnetic layer is easily scraped by the magnetic head under the environment at the high temperature, and the durability is not sufficient.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a metal thin film type magnetic recording medium having improved durability at high temperature.

Structure of the invention The present invention is to measure the emissivity of a magnetic surface at a wavelength of 1 μm at 100 ° C
A metal thin film type magnetic recording medium having a size larger than 0.3, which can improve durability under high temperature and low humidity.

Description of Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram showing a basic structure of a metal thin film type magnetic recording medium in an embodiment of the present invention. In FIG. 2, 3 is a substrate, 4 is a magnetic layer, and 5 is a heat dissipation layer. The magnetic layer 4 is formed on the substrate 3, and the heat dissipation layer 5 is further formed on the magnetic layer 4, so that the emissivity of the magnetic surface side surface at 100 ° C. at a wavelength of 1 μm is larger than 0.3.

Here, the substrate 1 is appropriately selected from plastic, metal, etc., and the magnetic layer 2 is made of Co, CoNi, Co-p, Ni-P, CoNip,
A magnetic metal material such as CoCr, FeCr, or FeCoCr is used as a main component, and the method for forming the magnetic layer 2 is appropriately selected from a vacuum deposition method, a sputtering method, an ion plating method, a metch method and the like. The heat dissipation layer 3 is appropriately selected from non-metal materials such as oxides, nitrides, carbides, plastics and resins. As the method for forming the heat dissipation layer 3, vacuum deposition method, sputtering method, ion plating method, CVD method, ion implantation method,
It is appropriately selected from coating method, plasma spraying method and the like.

The magnetic layer 4 has a thickness of 500 to 3,000Å from the viewpoint of electromagnetic conversion characteristics.
Desirably, the thickness of the heat dissipation layer is 1,000 Å or less, more preferably 500 Å or less, and the average roughness of the surface of the heat dissipation layer which is the magnetic layer side surface is 1,000 Å or less, more preferably 500 Å or less. Conventionally, in a metal thin film type magnetic recording medium having no heat dissipation layer, the magnetic surface side surface is close to metal, and even when affected by the surface shape or non-metal component,
The emissivity at a wavelength of 1 μm was 0.2 or less at most. In the present invention, the heat dissipation layer is formed of a material having a high emissivity, and the emissivity of the surface of the heat dissipation layer, which is the magnetic surface side, is set to 0.3 or more to enhance the heat dissipation of the magnetic surface side, and the conventional coating type magnetic The emissivity is similar to that of the recording medium or the oxide thin film magnetic recording medium.

Moreover, the measurement conditions and the measurement method of the emissivity will be described.

The limitation of the wavelength to 1 μm is intended to improve the measurement reliability in radiation at 100 ° C. The gist of the present invention is to utilize the cooling effect of the surface layer of the magnetic layer due to heat dissipation, and does not pose a problem with the emissivity of a single wavelength. However, when the ambient environment is 50 ° C, the surface of the magnetic layer becomes a temperature of 50 ° C or higher due to friction, and it is considered necessary to consider the heat dissipation at about 100 ° C. Therefore, the emissivity at 100 ° C can be measured accurately. As a condition, the wavelength is limited to 1 μm. The wavelength dependence of the emissivity can be easily realized by using various general filters, and it is considered that the emissivity has little wavelength dependence and can be easily measured. The emissivity can be measured by calibrating the radiant energy at 100 ° C with a radiation thermometer.

As described above, the metal thin film magnetic recording medium has good emissivity as in the case of the conventional coating type magnetic recording medium and oxide thin film type magnetic recording medium with the emissivity of the magnetic surface side surface being high at a high temperature such as 50 ° C. It is considered that even in the occasional use, the cooling effect due to radiation prevents the surface temperature on the magnetic surface side from rising and improves the durability.

A more specific embodiment of the present invention will be described below.

Example 1 Polyethylene terephthalate having a thickness of 10 μm was used as a substrate, and Co—Ni (20 wt%) was vapor-deposited along a cylindrical can having a diameter of 500 mm. The vapor deposition starts from the tangential direction at which the incident angle becomes 90 °, and gradually decreases until the incident angle becomes 40 °. O ₂ gas was introduced as an atmospheric gas during vapor deposition to obtain a coercive force. The obtained vapor deposition film has Hc = 1020 Oe, δ = 150
It was 0Å, Br = 4400 Gauss. Epoxy resin was coated on this magnetic film to form a heat dissipation layer. When the coating amount of the epoxy resin is small, it does not become a continuous film but has an island shape, and when the coating amount disappears, it becomes a continuous film gradually. Epoxy resin layer thickness is 80-
At 110Å, there is little change in film thickness, and in this region the electromagnetic conversion characteristics due to spacing loss are almost the same, and the emissivity changes due to the difference in coverage. FIG. 3 shows the relationship between the emissivity of these samples and the still life of a rotating cylinder having a ferrite head at 50 ° C. and 50% Rh. The emissivity is the emissivity at a wavelength of 1 μm at 100 ° C. As is clear from FIG. 3, the durability at 50 ° C. improves as the emissivity increases.

As described above, according to the present embodiment, by setting the emissivity at a wavelength of 1 μm at 100 ° C. to be 0.3 or more, the durability at high temperature can be improved. The durability of is greatly improved.

(Example 2) A 50 μm thick aromatic polyimide was used as a substrate, and Co-
Cr (20ωt%) is sputtered in Ar gas atmosphere, and the film thickness is 30
A 00Å CoCr perpendicular magnetic film was formed. After forming the CoCr film, continuously sputter it in a mixed gas atmosphere of Ar and N ₂ to obtain a thickness of 300
Å CoCr nitride formed. Samples with various emissivities were prepared by changing the mixing ratio of Ar and N ₂ gas.
The relationship between the emissivity of these samples and the still life of a rotating cylinder having an amorphous head at 50 ° C. and 50% Rh is shown in FIG. As is clear from FIG. 3, the durability at 50 ° C. improves as the emissivity increases.

As described above, according to the present embodiment, the emissivity at a wavelength of 1 μm at 100 ° C. of 0.3 or more can improve the durability at high temperature, and preferably 0.5 or more, the high temperature The durability of the time can be greatly improved.

In this example, the specific effects were shown for two kinds of samples, but it was confirmed that the same effects were obtained even in the combination of the above-mentioned other materials constituting the present invention.
Further, as shown in the embodiment, the heat dissipation layer can be formed separately from the magnetic layer or can be formed simultaneously. Further, in the previous embodiment, a magnetic tape was described as an example of the magnetic recording medium, but it is also possible to take the form of a magnetic disk or a magnetic sheet without departing from the scope of the present invention.

As described above, the present invention has a wavelength of 1 μ at 100 ° C. on the magnetic surface side.
By setting the emissivity at m greater than 0.3, it is possible to provide a metal thin film type magnetic recording medium having improved durability at high temperatures, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a sectional view showing a conventional metal thin film magnetic recording medium,
FIG. 2 is a sectional view showing a metal thin film type magnetic recording medium in an embodiment of the present invention, and FIGS. 3 and 4 are views showing improvement of durability in the embodiment of the present invention. 3 ... Substrate, 4 ... Magnetic layer, 5 ... Heat dissipation layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A 52-153707 (JP, A) JP-A 56-156931 (JP, A) JP-A 54-143111 (JP, A)

Claims (1)

[Claims] 1. A metal thin film type magnetic recording medium having an emissivity of more than 0.3 at a wavelength of 1 μm at 100 ° C. on the magnetic side surface.