JPH0132577B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thin film magnetic recording medium that has good lubricity and abrasion resistance and does not cause noise during running.

A magnetic recording medium obtained by forming a ferromagnetic thin film on a film support by methods such as vacuum evaporation, ion plating, sputtering, plating, etc.
The thickness of the magnetic layer has been reduced by about 1 inch compared to the conventional coating type.
It is possible to reduce the thickness by an order of magnitude, and the thickness is usually about 0.1 to 0.3μ. Biaxially stretched polyester film with magnetic film of such thickness,
When formed on a support such as a polyimide film, the shape of the surface thereof is almost the same as that of the support. For the purpose of high-density recording, it is desirable that the surface of the magnetic layer be smooth, but in consideration of friction with the magnetic head, it is necessary that the surface of the magnetic layer be uneven. Further, the support film itself requires appropriate surface properties in its manufacturing process, magnetic layer forming process, and the like. Taking these into consideration, a support having an appropriate surface roughness is actually used. On the other hand, since the ferromagnetic thin film easily abrades the magnetic head and itself, a protective layer of a resin thin film with excellent abrasion resistance is usually formed on the surface by applying a resin solution. The general tendency in this coating is that the thickness of the coating film becomes thinner at the protrusions on the surface of the magnetic layer and thicker at the depressions. In other words, the surface of the protective layer has less unevenness than the surface of the magnetic layer. It is the protruding portion that comes into contact with the magnetic head, and the thinness of the protective layer in that portion poses a problem in terms of service life. Furthermore, as the protrusion wears, the surface becomes flat, increasing the contact area with the magnetic head and increasing friction, which makes it more likely to cause squeaking. Flattening of the surface by forming the above-mentioned protective film tends to promote this problem. The present invention attempts to solve these problems of longevity and wear.

The present invention provides a magnetic recording medium in which a resin thin film is formed on the surface of a ferromagnetic thin film formed on a support, in which the resin thin film has a large number of microprotrusions whose cores are solid particles having a harder hardness than the resin. The present invention relates to a magnetic recording medium characterized in that it exists, and will be described in detail below with reference to the drawings.

1 and 2 show a part of a cross section of a magnetic recording medium, with FIG. 1 showing a conventional product and FIG. 2 showing a product according to the present invention. In the figure, 1 is a support such as a resin film, 2 is a ferromagnetic thin film formed on the surface of the support 1, 3 and 3' are resin thin films formed on the surface of the ferromagnetic thin film 2, and 4 5 indicates a resin portion in the resin thin film 3', and 5 indicates a solid fine particle portion in the resin thin film 3'. As shown in these figures, when solid particles 5 are present in the resin thin film 3' to increase the total resin film thickness in that area and form minute protrusions, it is these particles that directly rub against the magnetic head. Since it becomes a protruding part, abrasion resistance is reduced and tape sagging can be prevented.

As resin thin film materials, ordinary thermoplastic resins,
Thermosetting resins, ultraviolet curable resins, etc. can be used.
It is possible to use these resin liquids in which solid fine particles having a diameter equal to or larger than the resin film thickness to be obtained are dispersed. The resin thin film is a Co-based, Co-P-based, or Co-Fe film formed by a conventional method on a support such as a polyester film or a polyimide film.
It is formed directly on a ferromagnetic thin film such as ferromagnetic, Co-Ni, or Fe-Ni, or via a corrosion-resistant film such as Al or Cr, and its thickness is determined by taking into account spacing loss with the magnetic head. Usually 0.5μ or less, preferably 0.01~
0.1μ is appropriate.

Therefore, the diameter of solid particles is 0.5μ.
Hereinafter, it is preferably 0.02 to 0.1 μm, and fine powders having a harder hardness than the above-mentioned resins such as silica, titanium oxide, calcium carbonate, carbon, and organic pigments can be used. These solid particles are made into resin
If a volume ratio of 0.2 to 20 parts per 100 parts is mixed and applied in a thin film, a film having the shape shown in FIG. 2 can be obtained. At this time, various additives such as a lubricant, a dispersant, an antistatic agent, a leveling agent, and a rust preventive agent are added to the coating liquid as necessary to obtain desired surface characteristics. The appropriate density of microprotrusions on the surface is 100 to 10,000 per 100μ square.

Examples of the present invention will be described below.

Example 1 A film with a thickness of 0.3μ was deposited on a polyester film with a thickness of 6μ and a maximum surface roughness Rmax = 0.2μ by vacuum deposition.
The average film thickness was determined by applying a coating solution with the following composition on the Co ferromagnetic thin film and drying it.
After forming a thin film of 0.05μ (thickness calculated from the amount of coating), it was cut into a predetermined width to obtain a magnetic tape.

Polyamide resin (Tomide #395 from Fuji Kasei Kogyo Co., Ltd.) ... 100 parts by weight Cecyl alcohol (reagent) ... 10 parts by weight Ultrafine calcium carbonate (from Shiraishi Kogyo Co., Ltd., average diameter 0.05μ) ... ...5 parts by weight xylene (reagent) ...5000 parts by weight isopropyl alcohol (reagent) ...5000 parts by weight Using this magnetic tape, repeated recording and playback tests were conducted with a commercially available microcassette recorder. As a result, no abnormality was observed after 200 repetitions.

Comparative Example 1 A similar test was conducted using a liquid composition of Example 1 except that calcium carbonate was excluded, and as a result, tape crackling occurred after 40 recording/playback cycles.

Example 2 A liquid having the following composition was applied onto the same ferromagnetic thin film as in Example 1, and after drying to remove the solvent, the resin was cured by ultraviolet irradiation. The average thickness of the magnetic layer is
Microscopic observation at 0.05μ revealed that there were approximately 500 microprotrusions with solid particles as cores per 100μ square surface.

Epoxy resin (B6136J from Asahi Denka Kogyo Co., Ltd.)
...100 parts by weight silicone lubricant (Paintad M from Dow Chemical Co.) ...10 parts by weight epoxy resin curing catalyst (PP- from Asahi Denka Kogyo Co., Ltd.)
33) ...3 parts by weight organic pigment (Paliotol Yellow 1820L from BASF)
...1 part by weight The magnetic tape thus obtained was subjected to repeated running tests in the same manner as in Example 1, and no abnormality was observed after 200 runs.

Comparative Example 2 In Example 2, when the organic pigment was not added, tape cracking occurred after 200 repeated running tests, and head staining due to tape abrasion occurred after 150 running tests.

As is clear from the above Examples and Comparative Examples, the magnetic recording medium of the present invention has good abrasion resistance and stable running properties without causing any squeaks during running.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional magnetic recording medium, and FIG. 2 is a sectional view of an embodiment of the magnetic recording medium of the present invention. 1...Support, 2...Ferromagnetic thin film, 3'...
Resin thin film, 4...Resin portion, 5...Solid fine particles.

Claims (1)

[Claims] 1. In a magnetic recording medium in which a resin thin film is formed on the surface of a ferromagnetic thin film formed on a support, a large number of microprotrusions whose cores are solid particles with a diameter of 0.02 μm to 0.1 μm are present in the resin thin film. A magnetic recording medium characterized by: