JPS6383920A - Production of protective film for magnetic recording medium - Google Patents

Abstract

PURPOSE:To form a protective film having excellent wear resistance with ease of operation by preheating the vapor of a sublimatable arom. compd. which is solid at an ordinary temp. and atm. pressure, introducing said vapor into a reaction vessel, effecting plasma polymn. and depositing the same as a thin film on a feromagnetic material. CONSTITUTION:This process produced the protective film by evaporating an aliphat. aromatic hydrocarbon (arene) or the deriv. thereof alone or the mixture composed thereof, introducing the vapor thereof into the reaction vessel 1 and effecting the polymn. in the plasma atmosphere of gaseous argon. The sublimatable solid monomer put into a hermetic vessel 2 which permits preheating is held at a desired temp. and is supplied from a gas introducing nozzle 5 disposed in the desired position in the vessel 1 into said vessel while the condensation thereof on the way is prevented by a heated and insulated conduit 3. The heating piping is required to be disposed with an electrical heater or an heat medium around the same to make uniform holding of the temp. up to the point just before the nozzle even in the reaction vessel.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a protective film formed on a magnetic recording layer of a ferromagnetic metal thin film.

(Prior Art) Conventionally, magnetic recording media having a ferromagnetic metal thin film as a magnetic recording layer have been produced by vacuum deposition or plating of a ferromagnetic metal material on a metal disk substrate or tape substrate, or by resin coating (IJ). It is manufactured by spin-coding a polymer emulsion in which a ferromagnetic metallic material is dispersed. Although this ferromagnetic metal film has excellent characteristics for high-density recording, it has the drawback that it is easily subject to wear and loss due to contact with the head, and is easily oxidized by moisture in the air, causing changes in characteristics. Met. Therefore, attempts have been made to increase friction and improve corrosion resistance by providing various protective films on ferromagnetic metal thin films.

Particularly recently, plasma polymerization has been used to form resin protective films. However, in order to form a polymerized film by plasma polymerization as a protective film, a substance that is gaseous or liquid at room temperature and normal pressure is used as a monomer, and the performance of the obtained protective film is poor in surface lubricity and toughness. Met. Further, although the conventional Kazen sputtered film has lost some of its initial properties, it has been inferior in corrosion resistance and friction coefficient during long-term use.

(Problems to be Solved by the Invention) The present invention, as a result of intensive research in consideration of the current situation, provides a plasma polymerized film that is excellent in durability, wear resistance, and surface lubricity as a retention film. , developed a useful magnetic recording medium.

(Means for Solving the Problems) When the method of the present invention is applied to the manufacture of magnetic disks, a chemical plating layer such as N1-P is first adhered to an aluminum substrate as a base, and a post-processing such as polishing is applied. Afterwards, a ferromagnetic metal thin film is formed on the surface using a physicochemical method. Next, this is set in a plasma polymerization apparatus.

Sublimable substances that are solid at room temperature and pressure have not traditionally been considered as raw material monomers for plasma polymerization, and polymerized films have sometimes been obtained by sending liquid monomers together with carrier gas into a reaction vessel. Gases have mainly been used as raw materials.

In the method of the present invention, a sublimable solid monomer is constantly vaporized by heating it in a closed container, so that it can be handled in the same manner as conventional gaseous monomers.

Furthermore, it was found that a plasma polymerized film using a sublimable solid monomer is a hard material, has low surface friction, and has strong adhesion to metal surfaces, and is useful as a magnetic disk retainer film. Based on this background, the method of the present invention involves first holding a sublimable solid monomer in a heatable airtight container at a desired temperature, and allowing the monomer to react without causing condensation during the process through a heat-insulated conduit. The gas is supplied from a gas introduction nozzle placed at a desired position within the container. The heating piping used in the method of the present invention requires, for example, an electric heater arranged around the piping or a heating fluid interposed therebetween to maintain uniform heat even in the reaction vessel up to just before the nozzle. The heating temperature of the gas phase monomer at this time is desirably higher than the melting point of the monomer, and the solid monomer used in the method of the present invention must exhibit remarkable sublimation properties, and must be heated to a temperature lower than the melting point of the monomer. Even so, the purpose can be achieved. Therefore,
It is desirable to keep the normal heating temperature within ±10°C of the melting point. More desirably, it is preferable to heat and maintain the temperature below the condensation temperature of steam.

Therefore, when filling a heated sealed container with solid monomer,
Filling a container with granular or powdered monomer can also achieve the desired purpose, but if you want to smoothly convert the monomer from a solid to a gas, it is best to use a porous metal or inorganic material. Good results can be obtained by coexisting these porous bodies in the container at the same time. Desirably, the porous carrier is made to coexist with a solid monomer by removing the gas adsorbed on the porous carrier and then bringing the gas into contact with the liquid phase or gas phase of the monomer to remove the gas that becomes an impurity. It is useful to impregnate the solid monomer to be used in the porous structure in a vacuum, since the effect of not intervening in the reaction system can be obtained. for example,
When a solid polymer is impregnated into a molecular sieve as an inorganic porous carrier, the purpose can be achieved by introducing the molten sieve into the monomer melt in a vacuum or at a sufficiently high temperature. . By filling, for example, a heating container with the porous body impregnated with the solid phase monomer thus obtained, stable growth can be performed.

Also, the positional relationship between the adhered surface and the monomer gas supply nozzle is as follows:
This may vary depending on the specific conditions of the device, such as the plasma generation method, electrode shape, reaction vessel shape, gas flow rate, etc., but one characteristic of the monomer used in the present invention is that the monomer flow is controlled between the supply nozzle and the deposition surface. It is desirable that there be no obstructions.

In the method of the present invention, the sublimable organic compounds used are those that exhibit a solid phase at room temperature and normal pressure, and specifically include naphthalene, antho2cene, tetracene, pentacene, hexacene, perylene, 7-enanthrene, chrysene, and triphenylene. , Piren.

Aromatic hydrocarbons or derivatives thereof such as benzopyrene, violanthrene, coronene, opalene, or zophenyl,
diphenylmethane, dibenzyl, triphenylmethane,
These are aliphatic aromatic hydrocarbons (arenes) such as diphenylethylene, diphenylacetylene, and terphenyl, or derivatives thereof.

These organic compounds alone or as a mixture are placed in a heating container and vaporized, then introduced into a reaction container without condensation and subjected to plasma polymerization. In this case, polymerization is carried out in the presence of an inert gas such as argon, helium, or nitrogen in a glazma atmosphere of these gases.

When performing plasma polymerization using high frequency, the energy density supplied to the electrode should be 0.2 to 4 W/(X'', preferably 0.5 to 3 W/
(Make sure that it is within the range of
Keep it at 0-500W, preferably 100-450W. Note that the high frequency power source normally has an oscillation frequency of 13.56 MHz, but is not particularly limited to this frequency, and may have a frequency from direct current to microwave.

Also, the pressure inside the Pelger during plasma polymerization is 0.
．． 005 Torr to 3 Torr, preferably 0.0
It is best to maintain the temperature between 1 and 1.5 Torr, and the reaction time is from several seconds to 300 sec, preferably 10 sec.
It is possible to obtain the desired film thickness within ~100 sec. The thickness of the protective film obtained by the method of the present invention is 50~
Targets objects in the 1000X range. The method of the present invention is mainly suitable for manufacturing magnetic disks, but can also be applied to manufacturing other magnetic recording media such as magnetic tapes, floppy disks, and magnetic cards.

(Example) Examples (1) to (6) As shown in the drawing, in the vacuum chamber 1, there were glazma-generating flat plate high-frequency counter electrodes 6, 7 with a diameter of 130 Ill, and a 5-inch hard disk 4 as a memory disk on the surface of the electrode 6.
Place. A monomer supply nozzle 5 and an argon supply nozzle 8 as a carrier gas were installed in a vacuum container, and the inside thereof was evacuated using a vacuum pump 14.

Therefore, dibenzyl 2009- as a monomer has an internal volume of 2
It is sealed in a stainless steel container 2 at 00eC and preheated to 1
Evacuate to a high vacuum of 0 nHg and reduce the internal pressure to 0.8? /♂, a heater 11 was attached to the outer periphery of the stainless steel container 2 to maintain the temperature at 60±1°C.

This monomer was sublimated and gasified, and was supplied to the monomer supply nozzle 5 via the heating pipe 3 and the flow meter 9.

On the other hand, an argon gas 12 as a carrier gas is constantly maintained at a constant value (20 ccZ) through piping and a flow meter 10, and is supplied from an argon gas supply nozzle 8, and connected to a high frequency power source 13 and a high frequency counter electrode 6.7. , 13.
A plasma with a power of 200 W at 56 MHz was generated around the electrode.

Thus, as shown in Table 1, plasma polymerized protective films of various thicknesses were formed on the surface of the magnetic recording layer while varying the amount of monomer vapor supplied from the nozzle 5 and the reaction time, and the thickness of each film was determined. Durability was compared and tested by measuring the number of C8S cycles. The results are also listed in Table 1.

In addition, in order to compare with the method of the present invention, sputtered films using Kaden capacitors were deposited to approximately the same film thickness, and the number of CSS cycles was similarly measured for these films as well.

Note that the film thickness was measured using a Talystep device using a contact measurement method.

As is clear from Table 1, the magnetic disks with the plasma polymerized protective film formed by the method of the present invention were found to be highly durable.

Example (7) Molekiller sieves manufactured by Wako Pure Chemical Industries (10i pore diameter) 100
p, dibenzyl used in Examples 1 to 6 (melting point 52
℃) while melting at 30F, and then cooled and sealed in a stainless steel container of about 200 cc. A 60 W heater was attached around the container to form a magnetic disk protective film under the same conditions as in Example 1. was deposited.

A uniform film thickness was obtained over the entire surface of the disk, ensuring a stable plasma polymerization process.

(Effects) As described in detail above, the method of the present invention is extremely useful industrially, as it can easily operate and form a protective film with excellent abrasion resistance.

[Brief explanation of the drawing]

The drawing is a schematic explanatory diagram of an apparatus for illustrating a method of manufacturing a protective film for a magnetic recording medium according to the present invention. DESCRIPTION OF SYMBOLS 1... Pel jar, 2... Container, 3... Monomer supply piping, 4... Memory disk, 5... Monomer supply nozzle, 6, 7... High frequency counter electrode, 8...
Carrier gas supply nozzle, 9.10... Stream meter, 1 No.... Heater, 12... Carrier gas, 13...
High frequency power supply, 14...vacuum pump.

Claims (2)

[Claims] (1) When manufacturing a magnetic recording medium in which a ferromagnetic metal thin film is adhered to a substrate, in a method of manufacturing a protective film on the ferromagnetic thin film, a solid sublimable aroma is placed in a reaction vessel at room temperature and pressure. 1. A method for manufacturing a protective film for a magnetic recording medium, which comprises introducing a vapor of a group compound by heating it in advance, subjecting it to plasma polymerization, and depositing it as a thin film. (2) When generating vapor of a solid sublimable aromatic compound, the vapor obtained by adsorbing or impregnating a porous carrier with the compound and heating the same is used. 2. A method for producing a protective film for a magnetic recording medium according to item 1.