JPS62143225A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having the excellent durability of slipperiness by forming a fluoride glass layer on a thin ferromagnetic metallic film provided on a nonmagnetic substrate. CONSTITUTION:This magnetic recording medium is formed with the fluoride glass layer 3 on the thin ferromagnetic metallic film 2 provided on the nonmagnetic substrate 1. The fluoride glass is the glass consisting of a fluoride which is excellent as a solid lubricating agent or the glass dispersed with the fluoride in other glass. The loss of the fluoride which is the lubricating agent from the glass surface is, therefore, obviated even if the magnetic recording layer formed with the fluoride glass layer is worn by a magnetic head, etc. The magnetic recording medium having the excellent durability of slipperiness is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high recording density magnetic recording medium used in the information industry and the like.

Conventional technology Instead of conventional coating-type magnetic recording media, magnetic recording media in which a ferromagnetic metal thin film is deposited on a non-magnetic substrate using methods such as plating, sputtering, vacuum evaporation, and ion blating have a high recording capacity. It has been refined as a magnetic recording medium for density.

However, the magnetic recording medium using the ferromagnetic metal thin film produced by the method described above has problems in its wear resistance and runnability.

In the process of recording and reproducing magnetic signals, magnetic recording media
At this time, the magnetic recording medium must run smoothly and stably when it is placed in high-speed relative motion with the magnetic head. Also, wear and damage due to contact with the magnetic head must not occur.

However, the ferromagnetic metal thin film made by the method described above cannot withstand the harsh conditions of the magnetic recording and reproducing process, and the running becomes unstable due to the friction of the magnetic head, etc., and when running for a long time. In some cases, output may drop significantly due to wear, breakage, or generation of wear debris.

Therefore, a glass thin film layer is formed as a protective film on a ferromagnetic metal thin film, the glass thin film layer is treated with acid to form a fine pore structure in the glass thin film layer, and then a lubricant is applied to the glass thin film. It has been proposed to form a lubricated surface on the surface. (Japanese Unexamined Patent Publication No. 59-21'0538) Problems to be Solved by the Invention However, in this case, although there is a slight improvement in the initial lubricity, there is no lubricity durability. This is because the bond between the lubricant and the glass thin film is weak, at the level of physical adsorption, and the lubricant is scraped off by the magnetic head or the like that slides while the vehicle is running.

The present invention has been made in view of these points, and an object of the present invention is to provide a magnetic recording medium with excellent slipperiness and durability.

Means for Solving the Problems A fluoride glass layer is formed on a ferromagnetic metal thin film provided on a nonmagnetic substrate.

Functional fluoride glass is a glass made of fluoride, which is excellent as a solid lubricant, or a glass in which fluoride is dispersed in another glass. Therefore, in a magnetic recording medium on which a fluoride glass layer is formed, the fluoride, which is a lubricant, does not disappear from the glass surface even if it is abraded by a magnetic head or the like. As a result, a magnetic recording medium with excellent lubricity and durability can be obtained.

Example The figure is a cross-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 non-magnetic substrate.
is a fluoride glass layer.

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

Further, as the ferromagnetic material that can 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, such as an alloy of one or more of iron, cobalt, and nickel, or an alloy of these. There are also alloys that combine other metals such as manganese, chromium, titanium, sutritrium, samarium, and bismuth, as well as 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 evaporation method, a sputtering method, an ion brate ink method, or a plating method.

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

The fluoride glass used in the present invention is a mixture of fluoride or fluoride and glass.

Examples of fluorides include CaF2. PbF2. A
lF2°BeF2. NaF, MgF2. S r
F2. BaF2. Zr F4. An example is ThF4. These may be used alone or in combination.

Examples include acid salt glass and sulfate glass. Among these, oxide glass is superior in terms of wear resistance.

Examples of oxide glasses include Al2O3, St, 2°B
2O3, P2O3, GeO2, As2Q5, 5b203
．． B12o3゜P2O3,■206,5b205. As
2O3, ZrO2, Na20-3 to2. Na2O
-CaO-S to2. K2O-CaO-Sio2
゜BaO-3t, 2-B2O3, Na20-B2O3-
5io2゜Al(Po3)3. Fe2Q3-P2O3,
Na20-A12Q3-8102゜Al-S i-
An example is 0-N.

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

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

When the film thickness was greater than 50 nm, the output decreased due to spacing loss during signal reproduction.

Further, when the thickness is smaller than 5 nm, pinholes tend to occur, and lubricity cannot be expected.

〔Example〕

A 150 nm thick ferromagnetic metal thin film made of cobalt (90%)-chromium (10%) was formed on a 20 μm thick polyimide film substrate by vacuum evaporation. A piece with a diameter of 75 mm was cut from the substrate on which the ferromagnetic metal thin film was formed, and a 10 nm fluoride glass layer was formed on the ferromagnetic gold thin film by introducing argon gas and using high frequency sputtering. did. Argon gas pressure is 2 x 10
-4 Torr, and each fluoride glass having the following composition was used as a target.

Sample 1 BeF2 layer Sample 2A12o3-CaF2 layer (86:16 molar ratio) Sample 3 SiO2MgF2 layer (75:25 molar ratio) Sample 4 Na20-B2O2-8io2-PbF2 layer (
15:10:60:16 molar ratio) Sample s Al(PO3)3-AlF2-NaF-Mg
F2-Ca F S r F B a F 2
Layer (fluoric acid) (5:32:12:8:27:8:8
Molar ratio) [Comparative example] In the above sample a11, ferromagnetic gold JJ47i1.
1', on top of 14 (1), 5102-B203-Na20 (65:15:20) instead of fluoride glass layer
A 10 nm layer was formed by sputtering. Next, treated with a nitric acid/water solution in Section 5.Fluorine-based lubrication (Kreit Sox, manufactured by Kuwa Bussan Co., Ltd.) was applied to the spin code.

The dynamic friction coefficients of Samples 1 to 5 of Examples and samples of Comparative Examples were measured using a dynamic friction coefficient meter (DFPM type, manufactured by Kyowa Kagaku).

The head used was a steel ball with a diameter of 12mm, and the head load was 10o.
y, head running speed 1. ○Measured at mtn/s. The results are shown below.

From the data in the table, it can be seen that the magnetic recording medium of the example according to the present invention has a low coefficient of dynamic friction not only at the initial stage but also after 200 reciprocations, and is superior to the comparative example in terms of sliding durability.

Furthermore, when these magnetic recording media were run on a test machine with the same functionality as a commercially available floppy disk, all of the magnetic recording media of the examples ran stably even after 100 hours, and no wear scratches were observed. Ta. On the other hand, the magnetic recording medium of the comparative example ran unstable, and wear scratches were observed on the magnetic surface.

Note that although the above embodiments have been described with respect to magnetic disks,
It is clear that the magnetic recording medium of the present invention can also be applied to magnetic tapes, magnetic cards, etc.

Effects of the Invention The magnetic recording medium of the present invention has excellent slipperiness and durability and can maintain it for a long period of time.

[Brief explanation of drawings]

The figure is a sectional view of a magnetic recording medium in one embodiment of the present invention. 1...Nonmagnetic substrate, 2...Ferromagnetic metal thin film, 3...Fluoride glass layer. Name of agent: Patent attorney Toshio Nakao, 1 person/Nonmagnetic Motoiryo

Claims (4)

[Claims] (1) A magnetic recording medium in which a fluoride glass layer is formed on a ferromagnetic metal thin film provided on a nonmagnetic substrate. (2) The magnetic recording medium according to claim 1, wherein the fluoride glass is a fluoride. (3) The magnetic recording medium according to claim 1, wherein the fluoride glass is a mixture of fluoride and glass. (4) Claim 3 in which the glass is oxide glass
Magnetic recording medium described in Section 1.