JPS6361419A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve magnetic characteristics and corrosion resistance by forming a magnetic layer into the a-C layer of which a ferromagnetic metal is introduced by glow discharge in a gaseous mixture composed of a gaseous monomer of an org. compd. contg. the ferromagnetic metal and reducing gas. CONSTITUTION:The magnetic layer 12 into the a-C film layer of which the reduced ferromagnetic metal is introduced by executing the glow discharge treatment in the gaseous mixture composed of the gaseous monomer of the org. compd. contg. the ferromagnetic metal and the reducing gas is formed within the substrate 1 consisting of a polyester film, etc. to obtain a magnetic tape A. The ratio of the gaseous monomer contg. the ferromagnetic metal is preferably 10-60vol% with respect to the gaseous mixture. The packing ratio of the ferromagnetic metallic particles in the magnetic layer 12 is preferably 10-60vol%. Sublimating gases such as ferrocene, cobaltcene and nickelocene and gaseous monomers of carbonyl compd. of Fe and Co are used as the gaseous monomer of the org. compd. contg. the ferromagnetic metal. CH4, C2H4, etc., are used for the reducing gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a magnetic recording medium, and more particularly, to a method for manufacturing a magnetic recording medium with excellent magnetic properties and corrosion resistance.

[Conventional technology]

In general, magnetic recording media are made by binding magnetic powder together with a binder component onto a base film, or by depositing ferromagnetic metals or their alloys on a base film by vacuum deposition, etc. The magnetic layer is easily worn out due to violent sliding contact with the magnetic head, etc. In particular, ferromagnetic metal thin film magnetic recording media formed by vacuum deposition etc. have excellent high-density recording characteristics, but have a large coefficient of friction with the magnetic head. It is susceptible to wear and damage, and it also suffers from gradual oxidation in the air, resulting in deterioration of magnetic properties such as maximum magnetic flux density.

For this reason, in recent years, a method has been practiced in which a ferromagnetic metal is dispersed within an organic polymer compound layer by glow discharge treatment to form a magnetic layer to improve corrosion resistance.

(Japanese Patent Publication No. 60-31013) [Problems to be Solved by the Invention] However, in the method of forming a magnetic layer by dispersing a ferromagnetic metal in an organic polymer compound layer by glow discharge treatment,
There is a drawback that the ferromagnetic metal reacts with oxygen atoms, etc. in the residual gas excited by the glow discharge treatment and is oxidized, resulting in deterioration of magnetic properties, and corrosion resistance has not yet been sufficiently improved.

[Means for solving problems]

This invention was made as a result of intensive research in view of the current situation, and the ferromagnetic metal is reduced by performing a glow discharge treatment in a mixed gas of a monomer gas of an organic compound containing a ferromagnetic metal and a reducing gas. By forming a magnetic layer on a substrate, in which amorphous carbon is introduced into an amorphous carbon film layer, magnetic properties and corrosion resistance are sufficiently improved.

In this invention, the monomer gas of an organic compound containing a ferromagnetic metal used in forming the magnetic layer includes a sublimation gas such as ferrocene, cobaltocene, and nilakerosene, and a metal carbonyl compound such as pentacarbonyl iron and octacarbonyl dicobalt. Seven gases etc., CH4, C2
A mixture of an organic compound such as H4 with a 7-mer gas is preferably used.

When the organic compound 7-mer gas containing these ferromagnetic metals is mixed with a reducing gas such as hydrogen gas or carbon monoxide gas, and a glow discharge treatment is performed in this mixed gas, the organic metal compound 7-mer gas is decomposed. Then, the ferromagnetic metal contained in this monomer gas releases M, and oxygen atoms that are taken into the magnetic layer by reducing gases such as hydrogen gas and carbon monoxide gas, and residual gas or adsorption during glow discharge treatment. Oxygen atoms taken in from the molecules are removed and the free ferromagnetic metal is reduced to form a magnetic layer in which the ferromagnetic metal with improved oxidation resistance is introduced into the hard amorphous carbon film layer. Therefore, the deterioration of the magnetic properties due to oxidation of the ferromagnetic metal is sufficiently reduced, the magnetic properties are sufficiently improved, and the corrosion resistance is also sufficiently improved.

Such glow discharge treatment is usually performed by generating glow discharge using high frequency power, DC power, AC power, microwave power, etc., but 13.5 is relatively easy to handle.
RF power of 6 MHz is preferably used. Further, this glow discharge treatment can be performed in combination with heating evaporation or sputtering of the ferromagnetic metal. The gas pressure and power during the glow discharge treatment are set within the range of lXl0' to 5 torr so that a magnetic layer in which a ferromagnetic metal is introduced into the amorphous carbon film layer is well formed. is preferable, and the high frequency power is 0.1 to 10 W/cn.
! It is preferable to keep it within the range of . In addition, the content ratio of reducing gas in the mixed gas during glow discharge treatment is
It is preferable that the amount is within the range of 10 to 60% by volume based on the total amount of the organic compound containing the ferromagnetic metal and the ferromagnetic gas. If it is too small, the desired effect will not be obtained, and if it is too large, the film formation rate will be reduced. There are problems such as a decrease in the amount of water and an increase in the brittleness of the film.

In the magnetic layer formed in this way, the ferromagnetic metal introduced into the amorphous carbon film layer has an average particle size of 200 to 300 ml, although it varies depending on the 70% gas used.
If it is within the range of 0.00, the ferromagnetic metal particles are magnetically insulated by amorphous carbon, resulting in a single-domain particle-like structure, resulting in good magnetic properties and improved corrosion resistance. Further, the filling rate of the ferromagnetic metal particles in the magnetic layer is preferably within the range of 10 to 60% by volume based on the total components of the magnetic layer, and the filling rate is 1.
If it is less than 0% by volume, the filling rate of the ferromagnetic metal particles will be low and sufficient magnetic properties will not be obtained, and if it is more than 60% by volume, there will be no good magnetic insulation between the ferromagnetic metal particles. Therefore, the magnetic properties and corrosion resistance cannot be sufficiently improved. The filling rate of such ferromagnetic metal particles is controlled by the type and gas pressure of the monomer gas and additive gas, and a magnetic layer is formed in which the ferromagnetic metal particles are appropriately introduced and filled into the amorphous carbon film layer. Ru. Furthermore, hydrogen atoms and oxygen atoms in such a magnetic layer are
The atomic ratio to carbon atoms is preferably 0.2 times or less and 0.1 times or less, respectively; if the amount is too large, the number of places where crosslinks between carbon atoms are broken increases, resulting in poor durability. do not have.

Magnetic recording media obtained in this way include magnetic tapes based on synthetic resin films such as polyester films and polyimide films, and magnetic disks based on disks or drums made of synthetic resin films, aluminum plates, glass plates, etc. It includes various types of structures that come into sliding contact with a magnetic head, such as a magnetic head or a magnetic drum.

〔Example〕

Next, embodiments of the invention will be described.

Example 1 The glow discharge treatment apparatus shown in Fig. 1 was used, and the thickness was 10
A polyester film 1 having a thickness of 1.0 μm is moved from a raw roll 3 in a processing tank 2 via a guide roll 4 along the surface of a cylindrical can 5, and then wound onto a take-up roll 7 via a guide roll 6. cent. Then,
The inside of the processing tank 2 is evacuated to lx104 Torr by the exhaust system 8, the polyester film 1 is run at a speed of 3 m/min, and the gas introduction pipe 9 attached to the side wall of the processing tank 2 is evacuated.
, cyclopentadienyl dicarbonyl cobalt monomer gas was supplied at a flow rate of 20 sec, and hydrogen gas was supplied at a flow rate of 5 sec.
They were mixed and introduced at a flow rate of sec. At the same time, a frequency of 13.56 MHz is transmitted to the electrode 10 arranged below the cylindrical can 5.
A glow discharge treatment was performed by applying high frequency power of 50 W to form a magnetic layer with a thickness of 2000 nm in which cobalt was introduced into the amorphous carbon film layer. The cobalt filling rate in this magnetic layer was 35% by volume. Thereafter, the tape was cut to a predetermined width to produce a magnetic tape A as shown in FIG. 2, in which a magnetic layer 12 in which a ferromagnetic metal was introduced into an amorphous carbon film layer was formed on a polyester film 1. Note that 11 in FIG. 1 is a high frequency power source that applies high frequency to the electrode 10.

Example 2 In the glow discharge treatment in Example 1, 10% of octacarbonyl dicobalt monomer gas was used instead of cyclopentadienyl dicarbonyl cobalt monomer gas.
sccm, C2H4 monomer gas mixed at a flow rate of 10105e was introduced in the same manner as in Example 1, and carbon B5i in which cobalt was amorphous was introduced.
A magnetic layer with a thickness of 2,200 layers was formed and magnetic tape A was made. The cobalt filling rate in the magnetic layer was 40% by volume.

Example 3 Cobalt was introduced into the amorphous carbon film layer in the same manner as in Example 1 except that carbon monoxide gas was used instead of hydrogen gas in the glow discharge treatment in Example 1. A magnetic tape A was created by forming 1,800 magnetic layers. The cobalt filling rate in the magnetic layer was 50% by volume.

Example 4 In the glow discharge treatment in Example 3, octacarbonyl dicobalt 7-mer gas was used in place of cyclopentadienyl dicarbonyl cobalt 7-mer gas.
A magnetic layer with a thickness of 2000 mm in which cobalt was introduced into an amorphous carbon film layer was prepared in the same manner as in Example 3 except that a mixed gas of monomer gas of sccm and CH4 was introduced at a flow rate of 5 seconds. A magnetic tape A was produced. The cobalt filling rate in the magnetic layer is 5
It was 5% by volume.

Comparative Example 1 Cobalt was introduced into the amorphous carbon film layer in the same manner as in Example 1, except that the introduction of hydrogen gas was omitted in the glow discharge treatment in Example 1.
200 people formed a magnetic layer and created a magnetic tape. The cobalt filling rate in the magnetic layer was 30% by volume.

Comparative Example 2 Conomalt was introduced into the amorphous carbon moxibustion layer in the same manner as in Example 2, except that the introduction of hydrogen gas was omitted in the glow discharge treatment in Example 2. A layer was formed to create a magnetic tape. The cobalt filling rate in the magnetic layer was 33% by volume.

Regarding the magnetic tapes obtained in each example and comparative example,
Saturation magnetic flux density was measured and corrosion resistance was tested. The corrosion resistance test was carried out by leaving the obtained magnetic tape under conditions of 60° C. and 190% RH for 7 days, measuring the maximum magnetic flux density, and examining the rate of deterioration from the maximum magnetic flux density of the magnetic tape before being left.

Table 1 below shows the results.

Table 1 [Effects of the Invention] As is clear from Table 1 above, the magnetic tapes obtained by the present invention (Examples 1 to 4) are all compared to the conventional magnetic tapes (Comparative Examples 1 and 2). However, the saturation magnetic flux density is high and the deterioration rate of the maximum magnetic flux density is small, which indicates that the magnetic recording medium obtained by the present invention has further improved magnetic properties and corrosion resistance.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an example of a glow discharge treatment apparatus used in forming the magnetic layer of the present invention, and FIG. 2 is a partially enlarged sectional view of the magnetic tape obtained by the present invention. ■... Polyester film (substrate), 12... Magnetic layer, A... Magnetic tape (magnetic recording medium) Figure 1 Figure 2 A Magnetic tape 1 Polyester film

Claims (1)

[Claims] 1. When forming a magnetic layer on a substrate, a glow discharge treatment is performed in a mixed gas of a monomer gas of an organic compound containing a ferromagnetic metal and a reducing gas to transform the ferromagnetic metal into an amorphous state. 2. A method for manufacturing a magnetic recording medium, characterized in that a magnetic layer introduced into a carbon film layer is formed; 3. A method for manufacturing a magnetic recording medium according to claim 1, wherein the reducing gas is hydrogen gas. , the method for manufacturing a magnetic recording medium according to claim 1, wherein the reducing gas is carbon monoxide gas.