JP2552799B2 - Manufacturing method of magnetic storage medium - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a tape-shaped, drum-shaped or disk-shaped magnetic recording medium used for recording, recording or computer, and particularly excellent even after being exposed to high humidity conditions. And a method of manufacturing a magnetic storage medium having wear resistance.

[0002]

2. Description of the Related Art In recent years, for the purpose of improving recording density,
A magnetic storage medium has been proposed in which a ferromagnetic metal thin film made of iron, cobalt, nickel or an alloy thereof is provided on a substrate by vacuum deposition, sputtering or plating. These metal magnetic storage media are excellent in high-density recording property, but when used in a recording / reproducing apparatus, they run at high speed while physically contacting a magnetic head or the like, so they are also practically excellent in wear resistance. It is necessary.

In order to improve the abrasion resistance, a lubricant made of a hydrocarbon such as liquid or solid paraffin or the like is applied to the surface of the ferromagnetic metal, or a thin film is formed by a vacuum vapor deposition method. Proposed.

[0004]

Since the hydrocarbon protective film formed by these coating methods or vacuum deposition methods is soluble in a solvent, it is excellent in wear resistance under normal conditions, but under high humidity conditions. After being exposed to the bottom, it has the drawback that its wear resistance deteriorates significantly.

The inventors of the present invention have conducted various studies in order to remedy these drawbacks, and as a result, the hydrocarbon film as a protective film of the magnetic storage medium deteriorates in wear resistance even when exposed to high humidity conditions. The present invention has been achieved based on the finding that it does not.

That is, it is an object of the present invention to provide a method of manufacturing a magnetic storage medium which is excellent in wear resistance both under normal conditions and after being exposed to high humidity conditions.

[0007]

A method of manufacturing a magnetic storage medium according to the present invention comprises forming on a surface of a ferromagnetic metal thin film provided on a substrate by an ionization plasma decomposition polymerization reaction of a gas containing a hydrocarbon. It is characterized in that the ratio of carbon / hydrogen of the hydrocarbon protective film to be made is in the range of 50/50 to 98/2 in atomic ratio.

[0008]

In the present invention, the hydrocarbon protective film is formed on the surface of the ferromagnetic metal thin film provided on the substrate. A hydrocarbon protective film (hereinafter referred to as a protective film) has a carbon / hydrogen ratio of 50/50 to 98/2.
Such a protective film can be formed by an ionization plasma decomposition polymerization reaction of a gas containing a hydrocarbon gas.

The protective film thus formed is insoluble in a solvent and has an absorption peak of C--H bond according to its infrared spectroscopic analysis. Its elemental analysis shows that the atomic ratio of C / H is 5%.
It contains 0/50 or less hydrogen. As the hydrogen content decreases, the hardness of the film increases and
Its internal stress and dynamic coefficient of friction also increase. Therefore, as the protective film of the magnetic storage medium, the atomic ratio of C / H is 50/5.
It is necessary to set it in the range of 0 to 98/2, and a particularly preferable range is 60/40 to 90/10.

Since the protective film is extremely hard even after being exposed to high humidity conditions and has a very small friction coefficient, it is particularly useful and has excellent properties as a protective film to be laminated on a magnetic storage medium. Therefore, the magnetic storage medium manufactured by the method of the present invention is extremely practical when used under high humidity conditions.

The thickness of the protective film is preferably 2000Å
The thickness is particularly preferably 1000 L or less, and the spacing loss becomes large when the thickness is more than 1000 L.

[0012]

Next, a method of manufacturing a magnetic storage medium according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings.

FIG. 1 is a schematic view showing an example of an ionization plasma decomposition polymerization apparatus used for forming a protective film in the method of this embodiment. The reaction container 4 is a reaction container base 5
It is installed so that airtightness is maintained on the top of the. The reaction vessel base 5 is provided with a supply port 6 for a gas containing hydrocarbon and an exhaust pipe 7 connected to an exhaust pump. Further, electrodes 2 and 3 are provided in the reaction container 4, and plasma can be generated between the electrodes 2 and 3 by applying a voltage between them. A magnetic disk 1 to be coated with a protective film is arranged on the electrode 2, and thereby the same potential as that of the electrode 2 is applied to the magnetic disk 1, and an ionized plasma is generated on the magnetic disk 1. The protective film is formed by decomposition polymerization.

In the method of this embodiment, the magnetic disk 1 provided with a magnetic layer is set in the reaction vessel 4, and the inside of the reaction vessel 4 is evacuated through the exhaust pipe 7. Next, while continuing this exhaust, as a raw material gas into the reaction vessel 4 via the supply port 6, C ₂ H ₂ , C ₂ H ₄ , C ₂ H ₆ , CH ₄ , C ₄ H ₁₀ or the like is saturated or Unsaturated hydrocarbons, those obtained by gasifying liquid hydrocarbons such as C ₆ H ₆ and C ₆ H ₁₂ at normal temperature and pressure, or these gaseous hydrocarbons and Ar, He, Ne, H ₂ etc. A mixed gas with a gas other than hydrocarbons is supplied. In this way, by placing the inside of the reaction vessel 4 in a source gas atmosphere having a predetermined pressure and applying a predetermined voltage between the electrodes 2 and 3,
An ionized plasma decomposition polymerization reaction occurs, and a protective film is formed on the surface of the magnetic disk 1 having the magnetic layer.

In the present invention, the protective film may be formed directly on the magnetic layer, but Au, Pt, Ni-P, C may be used.
_{r, Ni, SiO 2, Si} , Ti, Ti-C or Si ₃ N
It can also be formed via a non-magnetic underlayer composed of ₄ or the like.

The operating conditions of the ionization plasma decomposition polymerization apparatus are as follows: the pressure in the reaction vessel is 0.001 to 10 Torr, a DC or AC voltage of 200 to 2000 V is applied between the electrodes, or a voltage of 200 to 2000 V and a frequency. It is preferable to apply a high frequency voltage of 100 KHz to 20 MHz.

In the magnetic storage medium thus manufactured, the ratio of carbon / hydrogen is 50 / atomic ratio on the surface.
Since the hydrocarbon protective film having a thickness of 50 to 98/2 is formed, it has an excellent effect that the wear resistance does not deteriorate even if this magnetic storage medium is exposed to high humidity conditions.

The examples manufactured according to the present invention will be described below in comparison with the comparative examples. Example 1 Production of plated disk Non-magnetic N on a mirror-polished aluminum plate with a diameter of 9 cm and a thickness of 2 mm
After electroless plating the iP alloy underlayer to a thickness of 50 μm, 30
It was mirror-polished to a thickness of μm, and a Co-Ni-P alloy (Co: 80
%, Ni; 15%, P: 5%) was electroless plated to a thickness of 0.1 μm. As a pretreatment for electroless plating, "Schuma Sensitizer" and "Schuma Activator" from Nippon Kanigen Co., Ltd. were used.

[0019]

[Table 1]

This plated disk is called plated disk A
Was used as a sample. Manufacture of Magnetic Storage Medium Using the ionized plasma decomposition polymerization apparatus having the structure shown in FIG. 1, various hydrocarbon gases were used as raw materials and a hydrocarbon film having a thickness of 800 Å was formed on the plated disk A under the conditions shown in Table 2 below. However, in Table 2, DC indicates a direct current and AC indicates an alternating voltage.

For comparison, a paraffin having a melting point of 50 to 70 ° C. was applied on the plating disk A to a thickness of 800 Å by spin coating using cyclohexane as a solvent.
This is Comparative Example 15.

[0022]

[Table 2]

Table 3 below shows the results of sliding tests conducted on these test materials under normal conditions and after moisture resistance. Example
No. 1 to No. 11 and Comparative Examples 12 to 15 were the same as the raw material gas, the pressure of the gas, and the applied voltage, the reaction time was lengthened to form a thick film, and the results of C and H elemental analysis The following Table 4
Shown in

[0024]

[Table 3]

[0025]

[Table 4]

However, the physical properties shown in Table 3 were measured as follows. 1) Dynamic friction coefficient measuring device The sliding physical property measuring device of the structure shown in Fig. 2 is used, the head is a sapphire ball with a diameter of 2 mm, and the head load is 5
g, and the dynamic friction coefficient was measured under the condition that the relative speed was 5 m / sec. 2) Measurement of number of sliding times Using the sliding property measuring device shown in Fig. 2, the head has a diameter of 2 m.
Using a sapphire ball of m, a head load of 10 g, and a relative speed of 10 m / sec, the number of times until the protective film broke was defined as the number of times of sliding. 3) CSS (contact, start, stop) test The head uses IBM-3350 type and the head load is 9.
The CSS test count was the number of cycles until a head crash occurred under the conditions of a rotation speed of 3600 rpm and an ON-OFF 30 second cycle at 8 g.

As a result, in Examples 1 to 12,
In both the normal state and after the moisture resistance, the number of sliding times and the number of CSS tests are large as compared with the comparative example, and the abrasion resistance is extremely excellent.

[0028]

According to the present invention, it is possible to provide a method of manufacturing a magnetic recording medium whose wear resistance does not deteriorate even when exposed to high humidity conditions.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an ionized plasma decomposition polymerization apparatus.

FIG. 2 is an explanatory diagram of a sliding property measuring device.

[Explanation of symbols]

 1, 17; magnetic disk 2, 3; electrode 4; reaction container 5; reaction container stand 6; gas supply port 7; exhaust pipe 18; holder 19; sapphire sphere 20; leaf spring 21; strain gauge 22; XY stage 23; Disk rotation motor 24; stand

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroshi Takeno 3-5-1 Asahimachi, Machida, Tokyo Electrochemical Industry Co., Ltd. Processing Technology Laboratory (56) Reference JP-A-57-135443 (JP, A)

Claims (1)

(57) [Claims] 1. A carbon / hydrogen ratio of a hydrocarbonaceous protective film to be formed on a surface of a ferromagnetic metal thin film provided on a substrate by an ionization plasma decomposition polymerization reaction of a gas containing a hydrocarbon in an atomic ratio. The manufacturing method of the magnetic storage medium is characterized in that the range is 50/50 to 98/2.