JPH07101506B2 - Magnetic recording medium - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high recording density magnetic recording medium used in the information industry field and the like.

2. Description of the Related Art A magnetic recording medium in which a ferromagnetic metal thin film is provided on a non-magnetic substrate by a plating method, a sputtering method, a vacuum deposition method, an ion plating method or the like instead of the conventional coating type magnetic recording medium has high recording performance. It is being studied as a magnetic recording medium for density.

However, the magnetic recording medium using the ferromagnetic metal thin film produced by the above-mentioned method has problems in its wear resistance and running property.

A magnetic recording medium is used for recording and reproducing magnetic signals.
Placed in high-speed relative motion with the magnetic head. At this time, the running of the magnetic recording medium must be smooth and stable. Also, no wear or damage due to contact with the magnetic head should occur.

However, the ferromagnetic metal thin film formed by the above method cannot withstand the harsh conditions of the magnetic recording and reproducing processes, and the friction of the magnetic head or the like makes the traveling unstable, or the traveling for a long time. In some cases, the output may be significantly reduced due to abrasion, damage, or generation of abrasion powder. Therefore, a glass thin film layer is formed as a protective film on the ferromagnetic metal thin film, the glass thin film layer is acid-treated to form a fine pore structure in the glass thin film layer, and then a lubricant is further applied to the glass thin film. It has been proposed to form a lubricated surface on the surface. (Japanese Patent Laid-Open No. 59-210538) Problems to be Solved by the Invention However, in this case, although the initial lubricity is slightly improved, the lubricity is not durable. This is because the bond between the lubricant and the glass thin film is weak to the extent of physical adsorption, and the lubricant is scraped off by a magnetic head or the like that slides during running.

The present invention has been made in view of the above points, and an object thereof is to provide a magnetic recording medium having excellent sliding durability.

Means for Solving Problems A fluoride glass layer is formed on a ferromagnetic metal thin film provided on a non-magnetic substrate.

The fluoride glass layer of the present invention is excellent as a solid lubricant,
A glass in which a fluoride is dispersed in glass. Therefore, in the magnetic recording medium having the fluoride glass layer formed, the fluoride as the lubricant does not disappear from the glass surface even if the friction is caused by the magnetic head or the like. As a result, a magnetic recording medium having excellent lubricity and durability can be obtained.

Example FIG. Is a sectional view of the magnetic recording medium of the present invention. In the figure, 1 is a non-magnetic substrate, 2 is a ferromagnetic metal thin film, and 3 is a fluoride glass layer.

Examples of the non-magnetic substrate 1 that can be used in the magnetic recording medium according to the present invention include polymeric materials such as polyvinyl chloride, cellulose acetate, polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, polyimide and polyamide, non-magnetic metal materials, glass and porcelain. There are films and plates made of known materials such as ceramic materials.

As the ferromagnetic material that can be used to form the ferromagnetic metal thin film 2 that can be used in the magnetic recording medium of the present invention, any known material can be used. For example, one or more alloys of iron, cobalt, nickel, or these materials can be used. And other metals such as manganese, chromium, titanium, phosphorus, yttrium, samarium, bismuth, and the like, and oxides of the above metals.

The ferromagnetic metal thin film 2 can be formed on the non-magnetic substrate 1 by any known method such as a vacuum deposition method, a sputtering method, an ion plating method, and a plating method.

In the present invention, the point is to provide the fluoride glass layer 3 on the ferromagnetic metal thin film 2 as described above.

The fluoride glass that can be used in the present invention is a mixture of fluoride and glass.

As the fluoride, for example, CaF ₂ , PbF ₂ , AlF ₂ , BeF ₂ , NaF, Mg
Examples are F ₂ , SrF ₂ , BaF ₂ , ZrF ₄ , ThF _{4 and the} like. These are used alone or in combination.

Examples of the glass include oxide glass, elemental glass, hydrogen-bonded glass, chloride glass, sulfide glass, carbonate glass, nitrate glass, and sulfate glass. Among these, oxide glass is excellent in wear resistance.

Examples of oxide glasses include Al ₂ O ₃ , SiO ₂ , B ₂ O ₃ , P ₂ O ₃ and GeO.
₂ , As ₂ O ₅ , Sb ₂ O ₃ , Bi ₂ O ₃ , P ₂ O ₃ , V ₂ O ₅ , Sb ₂ O ₅ , As ₂ O ₃ , ZrO ₂ , Na _{2
O-SiO 2, Na 2 O} -CaO-SiO 2, K 2 O-CaO-SiO 2, BaO-SiO 2 -
_{B 2 O 3, Na 2 O} -B 2 O 3 -SiO 2, Al (PO 3) 3, Fe 2 O 3 -P 2 O 3, Na 2 O
_{-Al 2 O 3 -SiO 2, Al} -Si-O-N and the like as an example.

According to the present invention, the fluoride glass layer 3 can be formed on the ferromagnetic metal thin film 2 by a sputtering method.

When the fluoride glass layer 3 is formed on the ferromagnetic metal thin film 2 according to the present invention, its thickness is preferably 5 to 50 nm.

When the film thickness was more than 50 nm, the output decreased due to spacing loss during signal reproduction. On the other hand, if the thickness is less than 5 nm, pinholes are likely to occur, and lubricity cannot be expected.

〔Example〕

Film thickness consisting of cobalt (90%)-chromium (10%) on a 20 μm thick polyimide film substrate by vacuum deposition.
A ferromagnetic metal thin film of 150 nm was made. Cut a piece with a diameter of 75 mm from the substrate on which this ferromagnetic metal thin film is formed,
Argon gas was introduced onto the ferromagnetic metal thin film to form a 10 nm fluoride glass layer by a high frequency sputtering method. The argon gas pressure was 2 × 10 ⁻⁴ Torr, and each fluoride glass having the following composition was used as a target.

Sample 2 Al ₂ O ₃ —CaF ₂ layer (85:15 molar ratio) Sample 3 SiO ₂ —MgF ₂ layer (75:25 molar ratio) Sample 4 Na ₂ O—B ₂ O ₃ —SiO ₂ —PbF ₂ layer ( 15: 10: 60: 15 molar ratio) sample _{5 Al (PO 3) 3 -AlF} 3 -NaF-MgF 2 -CaF 2 -SrF 2 -
BaF ₂ layer (fluoric acid) (5: 32: 12: 8: 27: 8: 8 molar ratio) [Comparative Example] In the above-mentioned Examples, SiO ₂ was used instead of the fluoride glass layer on the ferromagnetic metal thin film. -B ₂ O ₃ -Na ₂ O (65:15:20) layer
It was formed by a 10 nm sputtering method. Next, it was treated with a 5% aqueous nitric acid solution and spin-coated with a fluorine-based lubricant (Crytox, manufactured by Maruwa Bussan Co., Ltd.).

The dynamic friction coefficients of the samples 1 to 5 of the examples and the samples of the comparative examples were measured with a dynamic friction coefficient meter (DFPM type, manufactured by Kyowa Kagaku).

The head used was a steel ball with a diameter of 12 mm, and the head load was 100 g and the running speed of the head was 1.0 mm / s. The results are shown below.

From the data in the table, it is understood that the magnetic recording media of the examples according to the present invention have not only the initial dynamic friction coefficient but also the low dynamic friction coefficient after 200 reciprocations, and are superior to the comparative example in the sliding durability.

Further, when these magnetic recording media were run on a testing machine having a function equivalent to that of a commercially available floppy disk, all of the magnetic recording media of Examples were stable in running even after 100 hours, and no abrasion scratch was observed. It was On the other hand, the magnetic recording medium of the comparative example became unstable in running, and abrasion scratches were found on the magnetic surface.

Although the magnetic disk is shown in the above embodiment,
The magnetic recording medium of the present invention is obviously applicable to magnetic tapes, magnetic cards and the like.

EFFECTS OF THE INVENTION The magnetic recording medium of the present invention has excellent sliding durability and can maintain it for a long period of time.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetic recording medium according to an embodiment of the present invention. 1 ... Non-magnetic substrate, 2 ... Ferromagnetic metal thin film, 3 ... Fluoride glass layer.

Claims (2)

[Claims] 1. A magnetic recording medium in which a fluoride glass layer made of a mixture of fluoride and glass is formed on a ferromagnetic metal thin film provided on a non-magnetic substrate. 2. The magnetic recording medium according to claim 1, wherein the glass is an oxide glass.