JPS6122426A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the adhesion between a ferromagnetic layer and plasma- polymerized layers and to obtain excellent durability and corrosion resistance by providing the plasma-polymerized protective layers made of the specific constitution on the ferromagnetic layer formed on a base body. CONSTITUTION:The plasma-polymerized protective layer 17 is provided on the ferromagnetic layer 16 formed on the base body 1. The layer 17 is constituted with the plasma polymerized layer 17B which is provided on the front side and does not contain metal and the plasma polymerized layer 17A provided on the layer 16 side. The ferromagnetic layer 16 consists of the magnetic layer composed essentially of a magnetic metallic material and the layer 17A is directly disposed on the surface thereof. At least one kind among Sn, De, Hg, etc. are used for the metal to be incorporated therein. Si is incorporated into the layer 17B. F is incorporated into both polymers 17A, 17B. Such layer 17A is made into the dense polymerized layer having a high degree of crosslinking by the hydrophobic property and catalytic effect exhibited by the metal and therefore the corrosion resistance is improved and the adhesiveness to the layer 16 is improved, by which the excellent wear resistance is obtd. The sliding characteristic with a magnetic head is improved by the layer 17B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium having a ferromagnetic layer, and particularly to a plasma polymerized protective layer formed on the ferromagnetic layer.

[Conventional technology]

Magnetic recording media with a ferromagnetic layer as a magnetic recording layer are usually made by depositing ferromagnetic metals or their alloys on a base film by vacuum deposition, etc., and have characteristics suitable for high-density recording. However, on the other hand, the friction coefficient with the magnetic head is large, making it susceptible to wear and damage, and it also suffers from gradual oxidation in the air, degrading magnetic properties such as maximum magnetic flux density.

For this reason, various protective layers are provided on the ferromagnetic layer to improve durability and corrosion resistance.

In recent years, for example, a monomer gas of a fluorine-based organic compound is plasma-polymerized to form a plasma-polymerized protective layer of a fluorine-based organic compound on a ferromagnetic layer (Japanese Patent Laid-Open No. 58-8882).
No. 8, JP-A-58-1023'30), or by plasma polymerizing monomer gas of a silicon-based organic compound,
Plasma polymerization of silicon-based organic compounds i! ! Formation of Ji on a ferromagnetic layer has been carried out (Japanese Patent Laid-Open No. 57-8
No. 2229, JP-A-58-60427).

[Problem that the invention seeks to solve]

However, these plasma-polymerized protective layers do not have sufficiently good adhesion to the ferromagnetic layer, so they are subject to severe wear due to sliding contact with the magnetic head, damaging the ferromagnetic properties, or causing the ferromagnetic layer to be exposed directly to the air. The maximum magnetic flux density may deteriorate due to exposure, and durability and corrosion resistance have not yet been sufficiently improved.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above, and to provide a magnetic recording medium that has good adhesion between a ferromagnetic layer and a plasma polymerized layer, and has excellent durability and corrosion resistance.

[Means for solving problems]

To achieve this object, the present invention provides that the plasma polymerized image 8i layer formed on the ferromagnetic layer includes a plasma polymer layer not containing metal provided on the surface side and a ferromagnetic layer of the polymer layer. and a metal-containing plasma polymer layer provided on the side.

The magnetic layer formed on the substrate is made of γ-Fe203 powder, F
e1 powder Fe1O4 powder-i? e, o.

Powder, Co-containing Fe50'4 powder, Fe powder, C.

Magnetic powder such as powder or Fa-'Ni powder is coated on a substrate together with a binder and an organic solvent and dried, or Co + Fe + N l + Co-N
i + C.

It is formed using a ferromagnetic material such as -Cr, Co-P+ Co-Ni -P, etc., by means such as vacuum evaporation, ion blasting, sputtering, and plating.

The protective layer having the aforementioned metal-containing plasma polymer layer and metal-free plasma polymer layer can be formed, for example, by the following method.

That is, first, a mixed gas of an organic compound monomer gas and an organometallic compound monomer gas is plasma-polymerized by applying high frequency to form a plasma polymer layer containing metal directly on the ferromagnetic layer. Subsequently, a monomer gas of an organic compound is plasma-polymerized by application of high frequency, thereby forming a metal-free plasma polymer layer overlying the plasma polymer layer.

As the monomer gas, tetrafluoroethylene,
Fluorinated organic compounds such as hexafluoropropane,
Gases such as hydrocarbon compounds such as propane, ethylene, and propylene, and silicon-based organic compounds such as tetramethylsilane, octamethylcyclotetrasiloxane, and hexamethyldisilazane are used.

Examples of the monomer gas of the organometallic compound include tetramethyltin and tetramethylgermanium.

Gases such as diethylmercury, butadiene iron tricarbonyl, pentaethoxytantalum, and titanium ethoxide are used.

Radicals are generated by applying high frequency waves to these monomer gases, and these radicals react with each other to form a plasma polymerized film. When a monomer gas is plasma-polymerized, if a carrier gas such as argon or helium is present, the formation rate of a plasma-polymerized film is increased.

The thickness of the plasma polymerized protective layer is preferably within the range of 20 to 1000. If the film thickness is too thin, the durability and corrosion resistance effects of this protective layer will not be fully demonstrated.
If it is too thick, the spacing loss will be too large and will not adversely affect the electromagnetic conversion characteristics.

Polyester film is used as a magnetic recording medium.

Various forms can be taken such as a magnetic tape having a synthetic resin film such as a polyimide film as a base, a magnetic disk or a magnetic drum having a disk or drum as a base made of a synthetic resin film, an aluminum plate, a glass plate, etc.

〔Example〕

Next, embodiments of the invention will be described.

Example 1 A substrate made of a polyester film with a thickness of 10 μm was loaded into a vacuum evaporation apparatus, and cobalt was heated and evaporated under the residual gas pressure of an acid accumulation gas of 5×10-S torr to deposit a film on the polyester film to a thickness of 1000 μm. A thin ferromagnetic metal layer made of cobalt was formed.

Next, using the plasma processing apparatus shown in FIG. 2, the substrate 1 made of a polyester film on which the ferromagnetic gold Ws M layer was formed was separated into three chambers by partition walls 2 and 3. It was moved from the roll 5 along the circumferential side of a cylindrical can 6 whose circumferential side was exposed to the three chambers across the three chambers, and set so as to be wound onto the winding roll 7.

While the substrate 1 was running at a speed of 5 m/ml, 703 cc of tetrafluoroethylene monomer gas and 4 cc of tetramethyltin were introduced from the gas inlet pipe 8 in compartment A.
Tetrafluoroethylene monomer gas was introduced at a flow rate of 0 sec from the gas inlet pipe 9 of compartment B for 150 sec.
cm, and the gas pressure in each compartment was set to 0.10)-L in compartment A and 0.08)-L in compartment B, and the plasma generating electrode 10.

And the power density of 1) is 0.6 W/d, 13.56
Plasma polymerization was performed by applying a high frequency of MHz to form a plasma polymerized protective layer. The thickness of the plasma polymerized protective layer formed at this time was 320 mm.

In addition, 12 and 13 in the figure are compartments A and B, respectively.
Exhaust devices 14 and 15 for reducing the pressure inside are high-frequency power sources for applying high-frequency waves to the electrodes 10 and 1), respectively.

After plasma polymerization, it is taken out from the treatment tank 4, cut into a predetermined width, and coated with a ferromagnetic metal thin layer 16 and a plasma polymerized protective layer 1 on a polyester film 1) as shown in FIG.
A magnetic tape I8 was made by sequentially laminating the magnetic tapes 7 and 7.

In addition, 17A in the figure is a metal (tin) formed by compartmental hollowing.
and a fluorine-containing plasma polymer layer formed directly on the ferromagnetic metal thin layer 1)6. 17B is compartment B
A plasma polymer layer containing fluorine is formed on the plasma polymer 1) 7A and faces the surface.

Example 2 As monomer gases, tetramethylsilane gas and tetramethylgermanium gas were introduced at a flow rate of 100 sccrLl and 50 sec into compartment A, while compartment B
20% of tetramethylsilane gas was added as a monomer gas.
It was introduced at a flow rate of 0 sec. Plasma polymerization was performed in the same manner as in Example 1, except that the gas pressures in compartments A and H were 0.08) -L and 0.05 Torr, respectively, and the high frequency power density was 0.7 W/ctA. manufactured the tape.

Comparative Example 1 The gas pressure in compartment A was set to 0.1 without introducing tetramethyltin.
)) A magnetic tape having a plasma retention layer was manufactured in the same manner as in Example 1 except that the magnetic tape was changed to 1.

Comparative Example 2 A magnetic tape having plasma retention WIN was produced in the same manner as in Example 2, except that tetramethylgermanium was not introduced and the gas pressure in compartment A was set to 0.07).

The magnetic tapes obtained in each Example and each Comparative Example were tested for wear resistance and corrosion resistance. The wear resistance test was carried out by subjecting the obtained magnetic tape to a sliding test using a sliding tester and measuring the number of times until the surface of the ferromagnetic metal thin layer was scratched. In the corrosion resistance test, the obtained magnetic tape was tested at 60°C and 90°C.
The maximum magnetic flux density was measured after being left under conditions of %RH for 7 days, and the deterioration rate was determined by comparing the maximum magnetic flux density of the magnetic tape before being left as 100%. The table below shows the results.

〔Effect of the invention〕

The present invention has the above-mentioned structure, and the plasma polymer layer containing the metal becomes a dense polymer layer with a high degree of crosslinking due to the hydrophobicity of the metal and the catalytic action of the metal. As shown, a magnetic recording medium with a low deterioration rate, that is, excellent corrosion resistance, can be obtained. In addition, the adhesion between the ferromagnetic layer and the plasma polymerized protective layer is improved due to the compatibility of the metal contained in the monomer on the metal component in the ferromagnetic layer.
As shown in the above table, the magnetic recording medium has a large number of sliding movements, that is, it has excellent wear resistance. Note that if the protective layer is a single layer of a plasma polymerized layer containing metal, the coefficient of friction against the magnetic head is large. In this regard, in the present invention, since the surface side of the protective layer is a plasma polymer layer that does not contain metal, the friction coefficient is small and the magnetic recording medium has good sliding characteristics with the magnetic head.

In addition, in the above example, the plasma polymer layer not containing metal and the plasma polymer layer containing metal were made separately, but
The present invention is not limited thereto, and when forming one plasma-polymerized protective layer, it is also possible to provide a concentration gradient in the metal distribution in the protective layer.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a magnetic tape according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a plasma polymerization apparatus for forming a plasma polymerization protective layer of the magnetic tape. 1...Substrate, 16...Ferromagnetic metal thin layer, 17...
... Plasma polymerized protective layer, 17A... Plasma polymer layer containing metal, 17B... Plasma polymer layer not containing metal, 18... Magnetic tape. Figure 1 1 Substrate 16 Perishable layer 17 Plus! Goi dumb trowel shoulder 18, stone drum ki tehu. Figure 2

Claims (6)

[Claims] (1) In a magnetic recording medium in which a ferromagnetic layer is formed on a substrate and a plasma polymerized protective layer is provided on the ferromagnetic layer, the plasma polymerized protective layer is formed on the surface of a plasma layer that does not contain metal. 1. A magnetic recording medium comprising a polymer layer and a metal-containing plasma polymer layer provided on the ferromagnetic layer side of the metal-free plasma polymer layer. (2) In claim (1), the ferromagnetic layer is composed of a magnetic layer mainly made of a metal magnetic material, and a plasma polymer layer containing metal is directly formed on the surface of the ferromagnetic layer. A magnetic recording medium characterized by: (3) A magnetic recording medium according to claim (1) or (2), wherein the metal-free plasma polymer layer is a silicon-containing plasma polymer layer. (4) In claim (1) or (2), the metal element of the metal-containing plasma polymer layer is selected from the group of tin, germanium, mercury, iron, tantalum, and titanium. A magnetic recording medium characterized by containing at least one element. (5) Claim (1) or (2), characterized in that both the metal-free plasma polymer layer and the metal-containing plasma polymer layer contain silicon. magnetic recording media. (6) Claim (1) or (2), characterized in that both the metal-free plasma polymer layer and the metal-containing plasma polymer layer contain fluorine. magnetic recording media.