JPS60145532A - Manufacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium which is excellent in its durability and corrosion resistance by applying plasma polymerization to a ferromagnetic metallic thin film layer formed on a substrate, and simultaneously, spattering a metal in the monomer gas of an organic compound. CONSTITUTION:That which has formed a ferromagnetic metallic thin film layer 10 on a polyester film 1 being a base body is set to the lower face of a substrate 3 provided on the upper part in a treating tank 2, also copper 5 is set as a target onto an electrode 4 provided on the lower part in the treating tank 2, a monomer gas is led in from a leading-in pipe 6, also a plasma polymerization is executed by a high frequency output of the electrode 4, and a plasma polymerization protective film layer containing copper is formed. Thereafter, by cutting it to a prescribed width, it is possible to obtain a magnetic tape A which has laminated and formed successively the ferromagnetic metallic thin film layer 10 and the plasma polymerization protective film layer 11 containing copper on the polyester film 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic recording medium having a ferromagnetic metal thin film layer as a magnetic recording layer, and an object thereof is to manufacture the above-mentioned magnetic recording medium having excellent durability and corrosion resistance. The purpose is to provide a method.

A magnetic recording medium whose magnetic recording layer is a ferromagnetic metal thin film layer is
It is usually made by depositing metals or their alloys on a base film by vacuum deposition, etc., and has characteristics suitable for high-density recording, but on the other hand, it has a high coefficient of friction with the magnetic head and is susceptible to wear and damage. Moreover, there are drawbacks such as gradual oxidation in the air, which deteriorates magnetic properties such as maximum magnetic flux density.

For this reason, efforts have been made to improve durability and corrosion resistance by providing various protective film layers on ferromagnetic metal thin film layers, and in recent years, plasma polymerized protective film layers of organic compounds have been replaced with ferromagnetic metal thin film layers. It has been proposed to provide a thin 1IIXL layer.

However, this plasma-polymerized protective film layer does not have good adhesion to the ferromagnetic metal thin film layer, and the protective film layer peels off and breaks in a relatively short period of time due to sliding contact with the magnetic head, or when exposed to high temperature and humidity conditions. In some cases, the ferromagnetic metal thin film layer under the protective film layer corrodes in a relatively short period of time or the protective film layer peels off, and the durability and corrosion resistance have not yet been sufficiently improved.

As a result of various studies in view of the current situation, the inventors first formed a ferromagnetic metal thin film layer, and then exposed this ferromagnetic metal thin film layer to monomer gas of an organic compound to perform plasma polymerization. At the same time, when the metal is sputtered, a plasma polymerized protective film layer containing metal is formed on the ferromagnetic metal thin film, and the metal contained in this plasma polymerized protective film layer causes the ferromagnetic metal thin film made of the ferromagnetic metal to The inventors have discovered that this type of plasma polymerized protective film layer can be firmly adhered to the ferromagnetic metal thin film layer, and the durability and corrosion resistance can be sufficiently improved, and the present invention has been made based on this discovery. reached.

In this invention, the formation of a plasma polymerized protective film layer containing a metal on a ferromagnetic metal thin film layer is carried out in a treatment tank by forming a 7-mer gas of a fluorine-based organic compound, a 7-mer gas of a hydrocarbon compound, and a monomer of a silicon-based organic compound. It is carried out by plasma polymerizing gas etc. using high frequency waves and at the same time sputtering metal using the same high frequency waves to form a deposit on a ferromagnetic metal thin film layer.If metal is included in the plasma polymerized protective film layer in this way, This metal has good affinity with the ferromagnetic metal thin film layer made of ferromagnetic metal,
Adhesion to ferromagnetic metal thin film layers is improved. In addition, the metal contained in the plasma polymerization protective film layer acts as a catalyst to promote plasma polymerization.
X! The crosslinking density of I is improved. As a result, a relatively hard plasma-polymerized protective film layer is firmly deposited and formed on the ferromagnetic metal thin film, and even under high temperature and humidity conditions, the ferromagnetic metal thin film layer under the protective film layer will not corrode. Moreover, the protective film layer does not peel off, and the durability and corrosion resistance are sufficiently improved.

The metal binder 10 contained in such a plasma-polymerized protective film layer is preferably a metal such as cobalt, nickel, aluminum, copper, tungsten, chromium, silicon, titanium, tantalum, or an alloy thereof. is sputter-linked by high frequency at the same time as plasma polymerization and contained in 1 ml of plasma polymerization. The content ratio of these metals in the plasma polymerized protective film 1- is preferably within the range of 0.1 to 5% by weight; if it is too small, the desired effect cannot be obtained, and the content is less than 5% by weight. If the deposition conditions are set to increase the ratio, plasma polymerization will stop.

In addition, the plasma polymerized protective film layer is formed by plasma polymerizing monomer gas of an organic compound using high frequency waves in a processing tank and depositing it on the ferromagnetic metal thin film layer. Since the plasma-polymerized protective film layer is sputtered, metal is contained in the plasma-polymerized protective film layer. Examples of the monomer gas used to form this plasma polymerized protective film layer include C2F4 and C3F6.
monomer gas of hydrocarbon compounds such as propane, ethylene, propylene, etc., and monomer gas of silicon-based organic compounds such as tetramethylsilane, octamethylcyclotetrasiloxane, hexamethyldisilazane, etc. are preferably used, and in the monomer gas of these organic compounds, radicals are generated by high frequency, and the generated radicals react and polymerize to form a film. This radical is more likely to be generated when these organic compounds have double bonds or triple bonds, are metal salt compounds with a metal element at the end, or have functional groups such as OH groups. , those having these unsaturated bonds, metal elements, functional groups, etc. are more preferably used. In addition, when plasma polymerizing these 7-mer gases, if a carrier gas such as argon gas, helium gas, or oxygen gas is present together, the 7-mer gases will be deposited at a rate 3 to 5 times faster than when plasma polymerized alone. It is preferable to use these carrier gases together. When coexisting with these carrier gases, it is preferable that the composition ratio is within the range of 1:1 to 20:1 in terms of the ratio of carrier gas to 70% gas of the organic compound. If the carrier gas is too small, precipitation may occur. If the speed is too low, the amount of monomer gas will decrease and the plasma polymerization reaction will be hindered. In addition, when using a 7-mer gas of a hydrocarbon compound, it is not preferable to use oxygen gas as a carrier gas because an oxidation reaction will occur if oxygen gas is used as a carrier gas.

When performing such plasma polymerization at the same time as the metal sputtering, the output of the gas and high frequency waves is limited to plasma polymerization.As far as plasma polymerization is concerned, the deposition rate of plasma polymerized protected MIi becomes faster as the gas pressure increases; has a relatively low molecular weight and is plasma-polymerized, making it impossible to obtain a hard protective film layer.Also, when the gas pressure is lowered and the high-frequency output is directed, the deposition rate becomes slower, but on the other hand, a relatively hard protective film layer made of polymer is obtained. However, if the gas pressure is low and the high frequency output is too high, the monomer gas will turn into powder and a plasma polymerized protective film layer will not be formed.
The high frequency output should be within the range of (1,03~l).
W/cJ is preferable, the gas pressure is 0.05-1 Torr, and the high frequency output is 0.05-0.
More preferably, it is within the range of 5W/-.

However, metal sputtering is also performed at the same time, and this sputtering may not be performed well if the pressure of the gas such as argon gas used at the same time is lower than 0.01 Torr or, conversely, higher than 51 Torr. Also, if the high frequency output is lower than 0.05W/cTA, sputtering will not occur, and 5W/cLi! Since the deposition rate does not increase even if the gas pressure is increased, the gas pressure is set within the range of 0.02 to 0.5 Torr and the high frequency output is set within the range of (1,01 to I It is preferable to set the gas pressure in the range of W/cn+, more preferably to set the gas pressure in the range of 0.05 to 0.3 Torr, and set the frequency output in the range of 0.3 to 0.5 W/aA. The plasma polymerized protective layer 1 containing metal, which is precipitated and formed by simultaneous plasma polymerization and sputter linking, has excellent adhesion to the ferromagnetic metal thin film layer, is relatively hard and dense, and has a small coefficient of friction. Therefore, when a plasma polymerized protective film layer of an organic compound containing this kind of metal is formed, wear resistance and corrosion resistance are further improved.The thickness of the plasma polymerized protective film layer of an organic compound containing such a metal is , 20-100
It is preferable that the thickness be within the range of 0. If the film thickness is too thin, the durability and corrosion resistance effects of this protective film layer will not be sufficiently developed, and if it is too thick, the spacing loss will be too large and the electromagnetic conversion characteristics will deteriorate. No adverse effect on.

The material for forming the ferromagnetic metal thin film layer is C01Fe, N
i, Co-Ni alloy, Co-Cr alloy, Go-P
Ferromagnetic materials such as alloy, Co-N1-P alloy are used,
A ferromagnetic metal thin film layer made of these ferromagnetic materials is deposited on a substrate by means such as vacuum evaporation, ion blasting, sputtering, and plating.

In addition, as magnetic recording media, polyester film,
Various types of structures that come into sliding contact with magnetic heads, such as magnetic tapes based on synthetic resin films such as polyimide films, magnetic disks and magnetic drums based on disks and drums made of synthetic resin films, aluminum plates, glass plates, etc. includes.

Next, embodiments of the invention will be described.

Example 1 A polyester film with a thickness of lOμ was loaded into a vacuum evaporation apparatus, and cobalt was heated and evaporated under a vacuum of l×10μ to form a ferromagnetic metal thin film layer made of cobalt with a thickness of 100μ on the polyester film. Formed. Next, using the plasma processing apparatus shown in FIG. Copper 5 is set as a target on an electrode 4 made of stainless steel arranged in
m, and argon gas was introduced at a flow rate of 3Qsccm to set the gas pressure of C2F4 to 0.02 Torr, and the gas pressure of argon gas to 0.08 Torr. Plasma polymerization was performed for 5 minutes to form a plasma polymerized protective layer with a thickness of 500 mm and a copper content of 1 m%. Thereafter, the magnetic tape was cut into a predetermined size and a ferromagnetic metal thin film layer 10 and a plasma polymerized protective film layer 11 containing copper were successively laminated on a polyester film 1 as shown in FIG. In the figure, 7 is an exhaust system for reducing the pressure inside the processing tank 2, 8 is an earth shield, and 9 is a picture frequency power source for applying a high frequency to the electrode 4.

Example 2 In the formation of the plasma polymerized protective film layer in Example 1, S i (C,
H3) Same as Example 1 except that the same amount of monomer gas in 4 was used, the thickness was 500 mm, and the copper content was 1% by weight.
A plasma-polymerized protective film layer was formed to produce a magnetic tape.

Example 3 Example 1 except that the target 5 made of nickel was used instead of the target 5 made of copper.
Similarly, if jI is 500 people and the nickel content is 0.
．． A magnetic tape was produced by forming a plasma polymerized protective film layer with a concentration of 7%.

Example 4 Example 1 except that the target 5 made of cobalt was used instead of the target 5 made of copper in Example 1.
Similarly, the thickness is 500 mm and the cobalt content is 0.
A 7% by weight plasma polymerized protective 1* layer was formed and magnetic tape was applied.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the target 5 made of copper was not set and the electrode 4 made of stainless steel was used for plasma polymerization. A magnetic tape was made by forming a plasma-polymerized protective film layer.

Comparative Example 2 The same procedure as in Example 2 was carried out except that the target 5 made of copper was not set and the electrode 4 made of stainless steel was used for plasma polymerization. A magnetic tape was made by forming a plasma-polymerized protective film layer.

Regarding the magnetic tapes obtained in each example and comparative example,
Adhesion, durability and corrosion resistance were tested. The adhesion test was conducted by leaving the obtained magnetic tape under conditions of 30° C. and 90% RH for one day, and then carrying out a beering test to check for peeling. The durability test was carried out by subjecting the obtained magnetic tape to a sliding test using a sliding tester and measuring the number of times the magnetic tape was slid until the surface of the ferromagnetic metal thin film layer was scratched. Furthermore, a corrosion resistance test was conducted on the obtained magnetic tape at 60℃ and 90%RH.
The maximum magnetic flux density was measured after being left under the following conditions for 7 days, and the deterioration rate was compared with the maximum magnetic flux density of the magnetic tape before being left as 100%.

The table below shows the results.

As is clear from Table 2, peeling of the plasma polymerized protective film layer was observed in the magnetic tapes obtained in Comparative Examples 1 and 2, whereas in the magnetic tapes obtained by the manufacturing method of the present invention (
In all of Examples (through 4), no peeling of the plasma polymerized protective film layer was observed, and the magnetic tapes obtained in Examples 1 to 4 were superior to those obtained in Comparative Examples 1 and 2. , both have a large number of sliding movements and a small deterioration rate. Therefore, according to the manufacturing method of the present invention, the adhesion of the metal-containing plasma polymerized protective film layer to the ferromagnetic metal thin film layer is good, and as a result, It can be seen that a magnetic recording medium with much improved durability and corrosion resistance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an example of a plasma processing apparatus used in forming a plasma polymerized protective film layer containing a metal by the manufacturing method of the present invention, and FIG. FIG. 3 is a partially enlarged cross-sectional view of the magnetic tape. ■...Polyester film (substrate), IO...Ferromagnetic metal thin film layer, 11...Plasma polymerized protective film layer, A
...Magnetic tape (magnetic recording medium) Figure 1

Claims (1)

[Claims] ■, Ferromagnetic metal TFL on the base! form a layer, then
This ferromagnetic metal thin layer is exposed to a monomer gas of an organic compound to perform plasma polymerization, and at the same time, metal is sputtered to form a plasma polymerized protective film layer containing metal on the ferromagnetic metal thin film layer. A method for manufacturing a magnetic recording medium characterized by