JPS63113935A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve durability by forming a magnetic layer on a substrate, forming a protective film layer by a vapor deposition method on said layer and exposing the protective film layer to the gas of an org. compd. having carbon-carbon multiple bonds of <=8C. CONSTITUTION:A polyester film 1 on which a thin ferromagnetic metallic film layer is formed by using a plasma treatment device is moved along the peripheral side face of a cylindrical can 5 rotating across treating tanks 3, 4 separated above and below from a stock roll 2 and is so set as to be taken up on a take-up roll. The film 1 is then run along the peripheral side face of the can 5 and plasma polymn. is executed by impressing a high frequency from an electrode 8 under 0.05Torr gaseous pressure to form the plasma-polymerized protective film layer on the film to 200Angstrom thickness. Gaseous butadiene is the introduced into the treatment vessel 3 and the film 1 is exposed to the gas. After the film is cut to a prescribed width, the thin ferromagnetic metallic film layer 10 and the plasma-polymerized protective film layer 11 are successively laminated on the film 1. A magnetic tape A is thus prepd.

Description

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

[Conventional technology]

Generally, metals or their alloys are deposited on a base film by vacuum evaporation, sputtering, etc.
Alternatively, magnetic recording media made by bonding magnetic powder together with a binder component onto a base film are susceptible to abrasion of the magnetic layer due to violent sliding contact with a magnetic head etc. during recording and reproduction. Although the magnetic metal thin film layer has characteristics suitable for high-density recording, it has a large coefficient of friction with the magnetic head (and is susceptible to wear and damage).

Therefore, as a method to improve the durability of the magnetic layer, attempts have been made in recent years to form a protective film layer on the magnetic layer using the vapor deposition method. , providing a plasma polymerized protective film layer of an organic compound (Japanese Patent Laid-Open No. 58-8882)
No. 8, JP-A-58-102330, JP-A-57-82
229, JP-A No. 58-60427), or a protective film layer made of carbon is provided by a sputtering method, a CVD method, an ionized vapor deposition method, etc. (JP-A No. 60-60-2
No. 3406, JP-A-60-157726), etc. have been proposed.

[Problem that the invention seeks to solve]

However, in the protective film layer obtained by these conventional vapor deposition methods such as plasma polymerization, sputtering, and CVD, the protective film layer is formed by first dissociating motumer molecules and targets into radicals, etc. A large amount of unreacted active radicals remain inside,
There is a drawback in that the protective film layer tends to change over time, resulting in deterioration and variation in its function as a protective film layer.

[Means for solving problems]

This invention was made as a result of various studies in view of the current situation. First, a protective film layer is formed on the surface of the magnetic layer by a vapor deposition method, and then this protective film layer is Exposure to a gas containing an organic compound containing carbon-carbon multiple bonds reduces active residual radicals in the protective film layer, prevents deterioration of the protective film layer over time, and sufficiently improves durability. It is something.

The vapor deposition method in this invention is a method in which gas, liquid, or solid vapor is deposited on a substrate as an active species using plasma, heat, light, etc., and polymerization or chemical reaction occurs to form a thin film layer. For example, a gaseous or liquid or solid raw material monomer gas with sufficient vapor pressure is decomposed by a method such as plasma, heat, or optical excitation, and the decomposed active species are deposited on a substrate and polymerized. CVD methods such as plasma polymerization method (plasma CVD method), thermal CVD method, and photoCVD method, which grow a film by causing a reaction.
method, sputtering method in which a solid raw material is vaporized by rare gas plasma etc. and deposited on a substrate, vacuum evaporation method in which a solid raw material is heated and vaporized and deposited on a substrate, and gaseous raw material is ionized by electron beam irradiation etc. It includes general methods in which a gaseous and activated species is deposited on a substrate to grow a film, such as an ionized vapor deposition method in which a species is deposited on a substrate to cause a polymerization reaction to grow a film.

The raw materials used to form the protective film layer by plasma polymerization or ionized vapor deposition include, for example, gases such as methane, ethylene, propane, and tetrafluoroethylene, and liquids with sufficient vapor pressure such as benzene. , hexane, tetramethylsilane, hexamethyldisilazane, ferrocene, which is a solid with sufficient vapor pressure, etc.
Any gas, liquid or solid raw material with sufficient vapor pressure is suitably used. In addition, as the solid raw material used when forming the protective film layer by the sputtering method, inorganic raw materials such as graphite, 5i02, boron carbide, etc., or synthetic resin raw materials such as polyimide, polyester, polytetrafluoroethylene, etc. are preferably used. , Furthermore, the solid raw materials used in the gap for forming the protective film layer by the vacuum mowing method include B, Ta-
, T t and organic raw materials such as stearic acid and behenic acid are preferably used.

The protective film layer thus formed by the vapor deposition method is then coated with a carbon-carbon compound having 8 or less carbon atoms.
When a carbon compound with multiple bonds is exposed to organic compound gas,
The carbon-carbon bond of this organic compound is cleaved and grows in a graft-like manner by combining with a large amount of radicals remaining unreacted, unbonded, uncrosslinked, etc. in the protective film layer formed by the vapor deposition method. Remaining radicals in the protective film layer are reduced. Therefore, deterioration of the protective film layer over time is suppressed, a good protective film layer is formed, and the durability is sufficiently improved.

In this way, when exposing the protective film layer formed by the vapor deposition method to the gas of an organic compound having carbon-carbon multiple bonds having 8 or less carbon atoms, these gases are introduced in a vacuum and exposed. However, for a short time, the protective film layer may be exposed to the atmosphere and then exposed to the gas of these organic compounds. Such a number of carbon atoms is 8
As the gas of the organic compound having carbon-carbon multiple bonds, for example, gases such as ethylene, butadiene, 1-hexene, acetylene, propylene, tetrafluoroethylene, acrylic acid, and styrene are preferably used.

The thickness of the protective film layer thus formed is 20 to 1
It is preferable that the thickness be within the range of 0.000 people. If the film thickness is too thin, the durability effect of this protective film layer will not be fully exhibited, and if it is too thick, the spacing loss will be too large, which will adversely affect the electromagnetic conversion characteristics. affect

The magnetic layer formed on the substrate is made of γ-Fe203 powder, F
e3O4 powder, Co-containing r-Fe203 powder, CO-containing Fe3O4 powder, Fe powder, C.

Magnetic powder such as powder, Fe-Ni powder, etc. is coated on the substrate together with a binder component and an organic solvent, etc. and dried, or Co, Fe, N15Co-Ni alloy, Co-C
It is formed by depositing a ferromagnetic material such as r alloy, Co--P alloy, Co--N1-P alloy, etc. 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.

〔Example〕

Next, embodiments of the invention will be described.

Example 1 A polyester film with a thickness of 10 μm was placed in a vacuum evaporation apparatus, and cobalt was heated and evaporated under a vacuum of lXl0-51-1 to form a ferromagnetic metal thin film layer of cobalt with a thickness of 1000 μm on the polyester film. was formed. Next, using the plasma processing apparatus shown in FIG. 1, the polyester film 1 having a ferromagnetic metal thin film layer formed thereon is placed in a rotating cylindrical can 5 spanning treatment tanks 3 and 4 that are vertically separated from the original roll 2. The sheet was moved along the circumferential side of the sheet and set so as to be wound onto the winding roll 6. Next, the polyester film 1 is stretched for 2 m along the circumferential side of the cylindrical can 5.
/min, monomer gas of tetramethylsilane was introduced at a flow rate of 50 seconds from the gas introduction pipe 7 attached to the processing tank 4, and the gas pressure was set to 0.05 seconds.
)-le, a high frequency of 13.56 MHz is applied to the electrode 8 at 0,5 W/cIl! Plasma polymerization was performed by applying power at a power density of , to form a plasma polymerized protective film layer. The thickness of the plasma polymerized protective film layer at this time was 200. Next, butadiene gas was introduced at a flow rate of 300 sec from the gas introduction pipe 9 attached to the processing tank 3 to make the gas pressure 100 Torr, and the polyester film on which the plasma polymerized protective film layer was formed was run at a running speed of 0.1 m/min. It was rotated in the opposite direction and exposed for 20 minutes. Thereafter, the magnetic tape is taken out from the plasma processing apparatus and cut to a predetermined width, and a ferromagnetic metal thin film layer 10 and a plasma polymerized protective film layer 11 are sequentially laminated on a polyester film 1 as shown in FIG. I made A. In FIG. 1, 12 and 13 are exhaust systems for reducing the pressure in the processing tanks 3 and 4, respectively, and 14 is a high frequency power source for applying high frequency to the electrode 8.

Example 2 A plasma-polymerized protective film layer was formed in the same manner as in Example 1, except that styrene gas was introduced from the gas introduction pipe 9 in place of butadiene gas until the gas pressure reached 15 Torr and exposed for 30 minutes. A magnetic tape A was produced.

Example 3 A cobalt-nickel alloy was plated on a disc-shaped aluminum substrate to form a ferromagnetic metal thin film layer of cobalt-nickel alloy with a thickness of 1000 mm. Then the third
Using the sputtering apparatus shown in the figure, an aluminum substrate 15 on which a ferromagnetic metal thin film layer was formed was set on a substrate electrode 17 in a processing tank 16. Next, Ar gas was introduced at a flow rate of 20 sec from the gas introduction pipe 18 attached to the processing tank 16, and the gas pressure was set to 0.005 torr, and the target 19 made of graphite was set on the electrode 20.
．． Sputtering was performed by applying a high frequency power of 56 MHz at 100 OW to form a protective film layer made of carbon with a thickness of 500 MW. Next, butadiene gas was introduced at a flow rate of 300 sec through the gas introduction pipe 18 attached to the processing tank 16 to make the gas pressure 100 Torr, and the aluminum substrate 15 on which the plasma polymerized protective film layer was formed was exposed for 30 minutes to produce a magnetic disk. Ta. In addition, 21 in FIG. 3 is an exhaust system for reducing the pressure in the processing tank 16, and 22 is an exhaust system for reducing the pressure in the processing tank 16.
This is a high frequency power supply for applying high frequency to 0.

Comparative Example 1 A magnetic tape was produced in the same manner as in Example 1, except that the process of exposing it to butadiene gas was omitted.

Comparative Example 2 A magnetic disk was produced in the same manner as in Example 3, except that the process of exposing it to butadiene gas was omitted.

Regarding the magnetic tapes and magnetic disks obtained in each example and comparative example, immediately after manufacturing and at 60'C190%RH.
The friction coefficient was measured after being left for 7 days under the following conditions, and changes in the g-friction coefficient over time were investigated.

The table below shows the results.

〔Effect of the invention〕

As is clear from the above table, the magnetic tapes and magnetic disks obtained by the present invention (Examples 1 to 3) had a lower resistance after being left in comparison with the magnetic tapes and magnetic disks obtained in Comparative Examples 1 and 2. The coefficient of friction is small, and this shows that according to the manufacturing method of the present invention, changes in the coefficient of friction over time are well suppressed and the durability is further improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an example of a plasma processing apparatus used in forming a protective film layer, FIG. 2 is a partially enlarged sectional view of a magnetic tape obtained by the manufacturing method of the present invention, and FIG. 3 FIG. 1 is a schematic cross-sectional view showing an example of a sputtering apparatus used when forming a protective film layer. DESCRIPTION OF SYMBOLS 1... Polyester film (substrate), 10... Ferromagnetic metal thin film layer (magnetic layer), 11... Plasma polymerized protective film layer (protective film layer), 15... Aluminum substrate, A
...Magnetic tape (magnetic recording medium) Patent applicant Hitachi Maxell Ltd. Figure 2 1 Polyester film

Claims (1)

[Claims] 1. Form a magnetic layer on a substrate, then form a protective film layer on this magnetic layer by vapor deposition method, and then replace this protective film layer with an organic material having carbon-carbon multiple bonds having 8 or less carbon atoms. A method for producing a magnetic recording medium, which comprises exposing it to a compound gas.