JPH0740355B2 - 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 Conventionally, a so-called coating type magnetic recording medium in which ferromagnetic powder such as γ-Fe ₂ O ₃ , Co-containing γ-Fe ₂ O ₃ and CrO ₂ is dispersed in an organic binder and coated on a non-magnetic support. Has been developed,
For the purpose of further increasing the density, magnetic recording media in which a ferromagnetic metal thin film is formed on a non-magnetic support by the plating method, the sputtering method, the vacuum deposition method, the ion plating method, etc. are currently being actively researched. .

However, the magnetic recording medium using the ferromagnetic metal thin film produced by the above method has problems in friction and abrasion resistance.

That is, since the magnetic recording medium is in a state of high-speed relative motion with the magnetic head or the like in the process of recording and reproducing a magnetic signal, friction with contact with the magnetic head or the like causes unstable running, or If the vehicle is run for a long period of time, wear or damage will eventually occur, resulting in a significant decrease in output. Therefore, the magnetic recording medium is
Smooth running and durability are strongly desired.

Therefore, various proposals have been made so far for modifying a ferromagnetic metal thin film or providing a lubricant layer.
60-95728 is an example.

Problems to be Solved by the Invention However, in this case, although the lubricity in the initial stage is improved, the protective film peels off during long-time running, which is not sufficient.

Therefore, in view of the above point, the present invention has an object to provide a magnetic recording medium excellent in lubricity, running stability, and wear resistance.

Means for Solving Problems A first protective layer containing a phthalocyanine compound and a fatty acid, a salt of a fatty acid, or a fatty acid amide as a second protective layer on the surface of a ferromagnetic metal thin film provided on a non-magnetic substrate. Stack in sequence.

Action The first protective layer improves friction resistance and wear resistance, and the action of lubricity of the second protective layer is added to the first protection layer to obtain a magnetic recording medium excellent in running property and wear resistance. .

This is probably because the phthalocyanine compound is strongly bonded to the active group of the fatty acid, its salt, or fatty acid amide, and thus the lubricity is maintained.

Example FIG. 1 is a sectional view of a magnetic recording medium of the present invention. In the figure, 1 is a non-magnetic substrate, 2 is a ferromagnetic metal thin film, 3 is a first protective layer containing a phthalocyanine compound, 4 is a second protective layer containing a fatty acid or a salt thereof, or a fatty acid amide.

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, poly (cellulose acetate), polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, polyamide, polyimide and polysulfone, and non-magnetic metallic materials. , A film, a plate, etc. made of a known material such as glass, a ceramic material such as magnetism.

As the ferromagnetic material for forming the ferromagnetic metal thin film 2, known materials can be used. For example, one or more metals selected from iron, cobalt and nickel, or these and other metals such as manganese, chromium and titanium, There are alloys that combine phosphorus, yttrium, samarium, bismuth, etc.
There are oxides of the above metals.

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

In the present invention, a first protective layer of a phthalocyanine compound is formed on the surface portion of the ferromagnetic metal thin film 2, and a second protective layer containing at least one of fatty acid or salt thereof or fatty acid amide is further formed on the upper surface thereof. The point is to form a protective layer.

The phthalocyanine compound used in the present invention is metal-free and Cu, Ni, Co, Cr, Mg, Zn, Fe, Pb, Mn, V, Sn, Ca, Na or B.
It is a complex compound containing a monovalent to tetravalent metal such as e. Due to their chemical structure, these have a small shear stress and are excellent in friction resistance and wear resistance. What is more, they have excellent chemical stability and heat resistance, and therefore have good environmental resistance.

The fatty acid or salt thereof, or fatty acid amide is a compound containing a hydrocarbon chain having 12 to 26 carbon atoms. For example, in a fatty acid system, oleic acid, linoleic acid, palmitic acid, stearic acid, arachidic acid, linolenic acid are used. , Serotic acid, behenic acid, lignoceric acid and their Li salts, Na
There are salts, Ka salts and the like, and the fatty acid amide is an amide compound having a chemical structure similar to that of the fatty acid system. As will be described in Examples below, these hydrocarbon chains exhibit good lubricity, while the carboxylic acid stalk and the amide group are strongly bonded to the phthalocyanine compound of the first protective layer, thereby sliding the magnetic head or the like. Since the peeling off due to the magnetic field is small, a function of lower friction is exhibited, and a magnetic recording medium excellent in lubricity, running stability, and wear resistance can be obtained. It can be used alone or as a mixture. .

Also, if the number of carbon atoms in the hydrocarbon group is 11 or less, the lubricity deteriorates due to lower molecular weight and is easily decomposed by the heat generated during sliding, and if it is 27 or more, the price and availability are not only difficult. However, 12 to 26 are preferable because a great improvement in lubricity cannot be expected.

The formation of the first and second protective layers can be easily achieved by a dry method such as vapor deposition and a wet method such as spin coating and LB (Langmuir-Projet) method.
~ 400Å is preferred. The reason is that if the film thickness is less than 50 Å, pinholes are likely to occur during film formation, and the effect of the substrate (ferromagnetic metal thin film) will occur, so that sufficient lubricity cannot be obtained, while at 400 Å or more, signal output due to spacing loss will occur. This is because a decrease occurs.

Hereinafter, a specific example will be described.

Example 1 A ferromagnetic metal thin film having a film thickness of 1250Å (AES analysis) of Co—Cr (element ratio, composition of 8: 2) was formed on a polyamide film substrate having a film thickness of 12 μm by a continuous vapor deposition method (Sample No. 1).

In addition, nickel phthalocyanine (hereinafter referred to as NiPc
Abbreviated) with a film thickness of about 200Å (SEM analysis), and by the same method, stearic acid amide (abbreviated as StA below) 50Å
(Ellipsometer analysis) Layered and used as a sample (Sample
No.2).

Furthermore, samples (Sample Nos. 3 and 4) in which only NiPc and StA were respectively laminated on the ferromagnetic metal thin film were prepared, and the dynamic friction coefficient (μ _k ) was measured for comparative evaluation. The results are shown in Table 1.

The evaluation was performed with a DF-PM type friction coefficient meter manufactured by Kyowa Interface Science Co., Ltd., with load P = 50 g, speed v = 1 mm / s, and room temperature.
A steel ball with a diameter of 3 mm was used for the head.

According to Table 1, sample No.1 is initialized from mu _k is large, mu _k with to the running count is increased to increase the sample surface damage was woefully intense. In contrast, the sample
In No. 3, μ _k was small from the beginning and the value continued even after 200 passes, but since μ _k does not fall below 0.2, overall dynamic friction characteristics are high. Meanwhile, the sample
In No. 4, although μ _k is lower than Sample No. 3 in the initial stage, 1
After the lapse of 00 passes, the value gradually increased, and after 200 passes, the sample surface was damaged as if the peeling occurred, as in the case of sample No. 1.

On the other hand, in sample No.2, μ _k is smaller than the initial value, and its value is maintained stable even after 200 passes, and there is no abnormality on the sample surface. Was showing sex.

From the above, a phthalocyanine compound such as NiPc was formed as the first protective layer on the surface of the ferromagnetic metal thin film, and a fatty acid amide such as stearic acid amide was laminated as the second protective layer on the upper surface thereof. It can be seen that the magnetic recording medium can be realized as a recording medium excellent in running property and abrasion resistance.

Example 2 A ferromagnetic metal thin film having a film thickness of 1250 Å was formed on a polyimide film substrate having a film thickness of 12 μm by the same composition and method as in Example 1. About 150Å of copper phthalocyanine was vapor-deposited on this, and palmitic acid (Sample No. 5), erucic acid (Sample No. 6), lithium stearate (Sample
No. 7) and oil acid amide (Sample No. 8) were laminated in the same manner as in Example 1 to about 50 to 100Å to prepare a sample, and a steel ball of P = 10 g, v = 3 mm / s, head = φ6 mm was prepared. The dynamic friction characteristics were investigated under the conditions.

As a result, Sample Nos. 5 to 8 show good characteristics such that μ _k changes only slightly at the initial stage and after 200 passes, and no scratches are observed during surface observation. I understand.

Therefore, as in Example 1, by forming the first protective layer of the phthalocyanine compound and the fatty acid or its salt containing a hydrocarbon chain having 12 to 26 carbon atoms, or the fatty acid amide as the second protective layer, the first protective layer is formed. It can be seen that a magnetic recording medium with further improved friction and wear resistance can be obtained.

Example 3 A ferromagnetic metal thin film having a film thickness of 1400 to 2000Å was formed with an elemental composition such as Co, Cr, and Ni, and samples were prepared for the first and second protective layers with the constituent components shown in Table 3 (Sample No. .9 ~ 15), P = 25g, v
= 10 mm / s, head = φ6 mm steel balls were evaluated.

From the above, Sample Nos. 9 to 15 also show good lubricity of μ _k = 0.13 to 0.19 even after 200 passes or more even in the above test, and the observation results show that the surface of the magnetic medium is almost the same. It can be said that it is also excellent in abrasion resistance, such as no damage being observed.

Therefore, as can be seen from this example, the film thickness of the first and second protective layers is approximately equal to the thickness of the ferromagnetic metal thin film such as Co, Cr, and Ni.
A magnetic recording medium having a thickness of 50 to 400 Å can provide a magnetic recording medium having improved running property without spacing loss and excellent abrasion resistance.

Effects of the Invention According to the present invention, it is possible to realize a magnetic recording medium having excellent running properties and excellent wear resistance.

[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 ... first
Protective layer, 4 ... Second protective layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tokihiko Shimizu 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-60-38719 (JP, A) JP-A-60-38729 (JP, A) JP-A-60-89817 (JP, A)

Claims (2)

[Claims] 1. A first protective layer containing a phthalocyanine compound is provided on the surface of a ferromagnetic metal thin film provided on a non-magnetic substrate, and a fatty acid, a salt of a fatty acid, or a fatty acid amide is laminated as a second protective layer. A magnetic recording medium characterized by the above. 2. The magnetic recording medium according to claim 1, wherein the compound forming the second protective layer contains a hydrocarbon chain having 12 to 26 carbon atoms.