JPS6116026A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To decrease the coefft. of friction of the thin ferromagnetic metallic film layer formed on a base body and to improve the corrosion resistance thereof by providing a plasma-polymerized protective layer consisting of an org. compd. on said layer then irradiating UV rays to the protective layer. CONSTITUTION:The thin ferromagnetic metallic film layer 12 consisting of a metal or the alloy thereof is provided on the base body 1 and the plasma-polymerized protective layer 13 consisting of the org. compd. is formed thereon; thereafter UV rays are irradiated to the layer 13. The crosslinking density of the layer 13 is increased and the hard layer 13 can be formed by irradiating the UV rays to the layer 13 in the above-mentioned manner, by which the excellent wear resistance is obtd. The durability and corrosion resistance of a magnetic recording medium are thus improved.

Description

Detailed Description of the Invention [Field of Industrial Application] 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 more particularly, to a method for manufacturing a magnetic recording medium having excellent durability and corrosion resistance. The present invention relates to a method for producing a medium.

[Conventional technology]

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. It also has disadvantages such as gradual oxidation in the air and deterioration of 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 the ferromagnetic metal thin film layer, and in recent years, for example, plasma polymerization of fluorine-based organic compound monomer gas Then, a plasma-polymerized protective film layer of a fluorine-based organic compound is provided on a ferromagnetic metal thin film layer (JP-A-58-88828, JP-A-58-102).
No. 330), or a plasma-polymerized protective film layer of a silicon-based organic compound is provided on a ferromagnetic metal thin film layer by plasma polymerizing a monomer gas of a silicon-based organic compound (JP-A No. 57-82229, JP-A-Sho 57-82229; No. 58-60427) has been proposed.

[Problem that the invention seeks to solve]

However, the plasma-polymerized protective film layer of an organic compound obtained by this conventional method still does not have sufficient crosslinking density, so improvements in durability and corrosion resistance are still insufficient (
In particular, if the deposition speed is increased by increasing the gas pressure during plasma polymerization, the problem is that the crosslinking density is low and plasma polymerization is performed, making it impossible to obtain a hard protective film layer and good abrasion resistance. there were.

[Means for solving problems]

This invention was made as a result of various studies in view of the current situation. First, a plasma-polymerized protective film layer of an organic compound is formed on the surface of a ferromagnetic metal thin film layer, and then the plasma-polymerized protective film layer is coated with ultraviolet light. By irradiating the plasma-polymerized protective film layer with It has been sufficiently improved.

In this invention, the plasma polymerized protective film layer is formed on the ferromagnetic metal S film layer in a treatment tank using a hydrocarbon compound,
It is formed by subjecting monomer gases such as fluorine-based organic compounds and silicon-based organic compounds to plasma polymerization using high frequency waves and depositing them on the ferromagnetic metal thin film layer. Examples of the monomer gas used to form this plasma-polymerized protective film layer include monomer gases of hydrocarbon compounds such as propane, ethylene, and propylene, and C2F4.
．． Monomer gases of fluorine-based organic compounds such as C3Fs and monomer gases of silicon-based organic compounds such as tetramethylsilane, octamethylcyclotetrasiloxane, and hexamethyldisilazane are preferably used. Radicals are generated, and the generated radicals react and polymerize to form a film. In addition, when plasma polymerizing these monomer gases, if a carrier gas such as argon gas, helium gas, or oxygen gas is coexisting, the deposition rate is 3 to 5 times faster than when plasma polymerizing monomer gases alone. Therefore, it is preferable to use these carrier gases together. When coexisting with these carrier gases, it is preferable that the composition ratio be within the range of 1:1 to 20:1 in terms of the ratio of carrier gas to 70% gas of the organic compound; too little carrier gas may cause damage. The deposition rate decreases, and if the amount is too high, the amount of 7-mer gas decreases, which interferes with the plasma polymerization reaction. Note that when using a monomer 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 plasma polymerization, the higher the gas pressure and the higher the high frequency power, the higher the deposition speed, but the monomer gas has a relatively low crosslinking density and plasma polymerization makes it difficult to obtain a hard protective film layer. If the gas pressure is lowered and the radio frequency power is increased too much, the deposition rate will be slow, but at the same time a protective film layer with relatively high crosslinking density will be obtained. However, if the gas pressure is lowered and the radio frequency power is too high, the monomer gas will turn into powder. If the plasma polymerized protective film layer is not formed, the gas pressure is reduced to 0.
It is preferable that the high frequency power per square senna is within the range of 0.001 to 5 Torr, and the high frequency power per square senna is within the range of 0.03 to 5 W/ct, the gas pressure is 0.003 to 1 Torr, and the high frequency power per square senna is within the range of 0.003 to 5 W/ct. is more preferably within the range of 0.05 to 3 W/d. The plasma-polymerized protective film layer of an organic compound that is formed by plasma polymerization in this way is dense and has a small coefficient of friction. Therefore, when the plasma-polymerized protective film layer of this organic compound is formed, the wear resistance and corrosion resistance are further improved. improves. The thickness of such a plasma-polymerized protective film layer of an organic compound 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 film layer will not be sufficiently exhibited. If the thickness is too large, the spacing loss will be too large, which will adversely affect the electromagnetic conversion characteristics.

The ultraviolet light source used to improve the crosslinking density of the plasma polymerized protective film layer thus formed and to cure the plasma polymerized protective film layer includes a mercury lamp, a xenon lamp, and an excimer laser such as ArF and KrF. and N2 laser are preferably used. Such ultraviolet rays have an irradiation dose of 0.1-5 mW/c
It is preferable to irradiate within the range of a. If the irradiation amount is too small, the plasma polymerized protective film layer will not be sufficiently cross-linked and will not be cured sufficiently, making it impossible to obtain the desired effect.

Materials for forming the ferromagnetic metal thin film layer include Co, Fe, and N.
i, Co-Ni alloy, Co-Cr alloy, Co-P alloy,
A ferromagnetic material such as a Co-N1-P alloy is used, and 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, or plating. Ru.

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.

〔Example〕

Next, embodiments of the invention will be described.

Example 1 A polyester film with a thickness of 10 μm was loaded into a vacuum deposition device, and cobalt was heated and evaporated under a vacuum of 1×10−51 μl to form a ferromagnetic metal thin film layer of cobalt with a thickness of 100 μm on the polyester film. Formed. Then,
Using the plasma processing apparatus shown in FIG. 1, a polyester film 1 on which a ferromagnetic metal thin film layer is formed is moved from a raw roll 3 along the circumferential side of a cylindrical can 4 in a processing tank 2, and then rolled onto a take-up roll. I rolled it up to 5 cents.

Next, while running the polyester film 1 along the circumferential surface of the cylindrical can 4 at a running speed of 0.5 m/min, tetrafluoroethylene monomer gas was supplied from the gas introduction pipe 6 attached to the processing tank 2 at a flow rate of 200 sec. 13 at electrode 7 with a gas pressure of 0.05)
．． Plasma polymerization was performed by applying a high frequency of 56 MHz at a power density of 0.2 W/ci to form a plasma polymerized protective film layer. The thickness of the plasma polymerized protective film layer at this time is 2
There were 00 people.

Next, this plasma-polymerized protective film layer was irradiated with light from a 4KW high-pressure mercury lamp 9 for 1 minute through a light transmission window 8.

Thereafter, the magnetic tape A is cut to a predetermined width and a ferromagnetic metal thin film N12 and a plasma polymerized protective film M13 are sequentially laminated on a polyester film 1 as shown in FIG.
I made it. In the figure, 10 is an exhaust system for reducing the pressure inside the processing tank 2, and 11 is a high frequency power source for applying high frequency to the electrode 7.

Example 2 In the formation of the plasma polymerized protective film layer in Example 1, hexamethylene disilazane hexamer gas was used for 150 sec instead of tetrafluoroethylene hexamer gas.
A plasma polymerized protective film layer was formed and a magnetic tape was produced in the same manner as in Example 1 except that the gas was introduced at a flow rate of 0.0 m and the gas pressure was changed to 0.07 m. The thickness of the plasma polymerized protective film layer at this time was 250 layers.

Example 3 In forming the plasma-polymerized protective film layer in Example 1, propane monomer gas was introduced at a flow rate of 300 seconds in place of the tetrafluoroethylene chloride gas, and the gas pressure was adjusted to 0.151 seconds. A plasma-polymerized protective film layer was formed in the same manner as in Example 1, except that the applied high-frequency power density was changed from 0.2 W/cJ to 0.3 W/d, and a magnetic tape was produced. . The thickness of the plasma polymerized protective film layer at this time was 300 layers.

Example 4 Plasma polymerization protection was carried out in the same manner as in Example 1 except that instead of the light from the 4KW high-pressure mercury lamp 9 in Example 1, light from a 2KW xenon lamp was irradiated for 2 minutes through the light transmission window 8. A film layer was formed to create a magnetic tape. The thickness of the plasma polymerized protective film layer at this time was 300 layers.

Example 5 A polyimide film with a thickness of 50μ was loaded into a vacuum evaporation apparatus, and the polyimide film was heated to 300°C while being heated 3X.
The cobalt-chromium 11 alloy was heated and evaporated under a vacuum of 10-6 Torr to form a ferromagnetic metal thin film layer of 3,500 mm thick cobalt-chromium alloy (82:18 molar ratio) on the polyimide film. Next, Example 1 was added to this.
A plasma polymerized protective film layer was formed in the same manner as described above, and a magnetic tape was manufactured.

Comparative Example 1 A magnetic chip was produced in the same manner as in Example 1, except that the irradiation of the plasma-polymerized protective film layer with light from a high-pressure mercury lamp was omitted.

Comparative Example 2 A magnetic tape was produced in the same manner as in Example 2, except that the irradiation of the plasma polymerized protective film layer with light from a high-pressure mercury lamp was omitted.

Comparative Example 3 A magnetic tape was produced in the same manner as in Example 3, except that the plasma polymerized protective film layer was not irradiated with light from a high-pressure mercury lamp.

Comparative Example 4 A magnetic tape was produced in the same manner as in Example 5 except that the formation of the plasma polymerized protective film layer was omitted.

Regarding the magnetic tapes obtained in each example and comparative example,
The coefficient of friction was measured and the durability and corrosion resistance were tested. The durability test was carried out by subjecting the obtained magnetic tape to a sliding test using a sliding testing machine, and measuring the number of times of sliding until the surface of the ferromagnetic metal vi# film layer was scratched. In addition, for the corrosion resistance test, the obtained magnetic tape was left under the conditions of 6°C 190% RUT for 7 days, the maximum magnetic flux density was measured, and the maximum magnetic flux density of the magnetic tape before being left was taken as 100%, and compared with this. The deterioration rate was investigated based on the value. In addition, when the surface of the magnetic tape obtained in Comparative Example 4 was observed with the naked eye in addition to the corrosion resistance test, many spot corrosion was observed in the magnetic tape obtained in Comparative Example 4. No abnormality was observed in the gloss or the like.

The table below shows the results.

〔Effect of the invention〕

As is clear from the above table, the magnetic tapes obtained in the present invention (Examples 1 to 5) are all the same as Comparative Examples 1 to 4.
Compared to the magnetic tape obtained in It can be seen that as a result of hardening, a magnetic recording medium with further improved durability and corrosion resistance can be obtained. In addition, the magnetic tape obtained in Comparative Example 4 had many pitting corrosions, but the magnetic tape obtained in Example 5 showed no abnormality in surface gloss, indicating improved corrosion resistance. I understand.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an example of a plasma processing apparatus used in forming a plasma polymerized protective film layer, and FIG. 2 is a partially enlarged sectional view of a magnetic tape obtained by the manufacturing method of the present invention. .

Claims (1)

[Claims] 1. Form a ferromagnetic metal thin film layer made of metal or an alloy thereof on a substrate, form a plasma polymerized protective film layer of an organic compound on this ferromagnetic metal thin film layer, and then apply ultraviolet rays to this plasma polymerized protective film layer. A method for manufacturing a magnetic recording medium characterized by irradiating