JPH01320632A - Magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To improve wear resistance and durability and to exhibit good magnetic characteristics by forming a lubricating agent film of a nonionic surfactant. CONSTITUTION:The lubricating agent film of the magnetic recording medium constituted by laminating a magnetic film, protective film and the lubricating agent film successively on a substrate is formed of the nonionic surfactant. The nonionic surfactant has >=1 groups contg. 6C hydrocarbon and >=2 hydroxyl groups. The contact friction force generated between a head and the magnetic recording medium is decreased and the lubricating agent film and a plasma- polymerized protective film are securely bonded according to the resultant magnetic recording medium. As a result, the surface of the recording medium is maintained in a good state in the use over a long period of time.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a magnetic recording medium having a magnetic recording layer made of a magnetic thin film suitable for high-density magnetic recording, and a method for manufacturing the same, and more specifically relates to a magnetic recording medium suitable for high-density magnetic recording and a method for manufacturing the same. The present invention relates to a magnetic recording medium with excellent properties and durability, and a method for manufacturing the same.

[Prior Art] A magnetic recording medium having a magnetic recording layer made of a magnetic metal thin film is manufactured by depositing a metal magnetic material on a substrate made of a file, disk, etc. by sputtering, vacuum deposition, or the like.

Such magnetic recording media have characteristics suitable for high-density recording. However, the coefficient of friction with the magnetic head is large,
It was susceptible to friction and damage. In addition, the magnetic metal thin film is
The problem is that magnetic properties deteriorate due to oxidation in the atmosphere.

In order to solve these problems, methods such as providing a protective film on the magnetic metal thin film have been carried out. As this protective film, a plasma polymerized film is provided on a magnetic metal film (Japanese Unexamined Patent Publication No. 58
No. 88828 and Japanese Patent Application No. 84966/1983) have been proposed. However, with these materials, a sufficient coefficient of friction has not yet been obtained. Therefore, it has been proposed to provide a lubricant layer on the protective film layer (Japanese Patent Laid-Open No. 59-1546
No. 45, JP-A-62-58416).

[Problems to be Solved by the Invention] However, even with these magnetic metal thin films provided with a plasma polymerized protective film and further provided with a lubricant layer thereon, the coefficient of friction was still insufficient1. However, during actual use, the coefficient of friction increases over time, reducing durability.

The present invention has been made in view of these points, and provides a magnetic recording medium that is excellent in friction resistance and durability and can exhibit extremely good magnetic properties, and a method for manufacturing the same.

[Means for Solving the Problems] That is, the present invention provides a magnetic recording medium in which a magnetic film, a protective film, and a lubricant film are sequentially laminated on a substrate, in which the lubricant film is formed of a nonionic surfactant. This is a magnetic recording medium characterized by the following.

The present invention also includes a step of forming a magnetic film on a substrate, a step of forming a plasma polymerized film on the magnetic film, and a step of forming the plasma polymerized film on a gas containing a nonionic surfactant and oxygen.
This method of manufacturing a magnetic recording medium is characterized by comprising the step of exposing the substrate provided with the magnetic film and forming a lubricant film on the plasma polymerized film.

Here, the plasma polymerized protective film provided on the magnetic metal thin film contains hydrocarbon-based organic substances, silicon-based organic substances, etc. in the reaction tank.
Furthermore, it can be obtained by using these organic substances containing oxygen, nitrogen, and fluorine as monomers and subjecting them to plasma polymerization by glow discharge.

As this monomer, commonly known monomers can be used, or the surface components of the obtained plasma polymerized protective film are composed of carbon, hydrogen, and oxygen, and the elemental ratio of hydrogen/carbon is 1 or less, and oxygen It is desirable that the elemental ratio of /carbon is 0.22 or more. The reason for this is to strengthen the degree of adhesion of the plasma polymerized protective film and the lubricant film made of a nonionic surfactant deposited thereon. From this point of view, the following monomers are suitable.

Namely, naphthalene, anthracene, tetracene, pentacene, noxacene, perylene, phenanthrene, chrysene, triphenylene, pyrene, benzopyrene, violanthrene, coronene, operenediphenyl, diphenylmethine, dibenzyl, triphenylmethane diphenylethylene, diphenylacetin, terphenyl, etc. It is. Furthermore, benzene and its derivatives are also relatively good as the above-mentioned monomers.

Further, when plasma polymerizing these monomers, it is preferable to coexist a carrier gas such as argon, helium, or oxygen because the reaction rate can be increased.

Moreover, since the above-mentioned monomer is a sublimable solid, the monomer can be vaporized by bubbling the above-mentioned carrier gas into the molten monomer.

For glow discharge, power sources ranging from direct current to microwaves can be used. In this case, for example, if a 13.56 MHz high frequency power source is used, the energy density will be 0.2 to 4
W/CRJ, high frequency power supply output 30~500W
It is preferable to In addition, when this output is 100 W or more and the above-mentioned monomer is used, the elemental composition of the plasma polymerized protective film obtained is 1 or less in the hydrogen/carbon ratio,
The oxygen/carbon ratio can be 0.22 or more.

The lubricant film is a nonionic surfactant, and general surfactants such as ethylene oxide can be used. Desirably, it is a nonionic surfactant having one or more groups containing a hydrocarbon having 6 or more carbon atoms and having two or more hydroxyl groups. Examples of such nonionic surfactants include:

However, R is an alkyl group or alkoxyalkyl group containing a hydrocarbon having 6 or more carbon atoms, or an unsaturated aliphatic hydrocarbon group, and m+ '+ p is 1 to 15
It is an integer up to 0.

It is thought that this surfactant provides high lubricity because the hydroxyl groups bond with carbonyl groups, ether groups, and hydroxyl groups, which are polar groups on the surface of the plasma-polymerized protective film, through Van der Waals forces.

This lubricant film combines the above-mentioned surfactant with water and acetone.
It can be dissolved in a solvent such as toluene, hexane, cyclohexanone, etc. and applied onto a plasma polymerized protective film by a spin code method, a dipping method, or a spray method.

It is also possible to vaporize the surfactant and expose the plasma polymerized protective film to the vapor and deposit it thereon. Furthermore, preferably, the lubricant film is firmly adhered to the plasma polymerized protective film by mixing the surfactant gas with a gas containing oxygen gas and exposing the plasma polymerized protective film to this mixed gas. I can do it. This is because oxygen gas and/or oxygen gas and a surfactant are added to residual active groups such as free radicals during plasma polymerization that remain in the plasma polymerized protective film until the lubricant film is formed. It is thought that strong adhesion is possible. At this time, the concentration of the surfactant and oxygen gas is preferably such that the surfactant has a volume fraction of 1% or less and the oxygen gas has a volume fraction of 10% or more, and atmospheric air can also be used.

In order to easily create these gas mixtures, it is sufficient to leave the surfactant together with the atmosphere inside a somewhat sealed container, and by doing so, a gas mixture with a concentration corresponding to the vapor pressure of the surfactant can be obtained. It will be done. The deposition process can be carried out by leaving the semi-finished product layered up to the plasma polymerized protective film inside this container. Further, as conditions for the adhesion treatment at this time, a temperature in the range of room temperature to 200°C can be used, but a temperature in the range of 60 to 120°C is particularly preferable. Also, depending on the type of surfactant, the treatment time is 9.6 hours at 60℃, 24 hours at 80℃, 100℃
The standard time is 3 hours at ℃, and about 0.5 hours at 120℃. The thickness of the plasma polymerized protective film is 50 to 500, and the thickness of the lubricant film is 1/10 to 1/3 of that of the plasma polymerized protective film.
is preferred.

The thinner the thickness of this lubricant film, the better. The reason for this is that if the thickness is too thick, when the magnetic recording device is assembled, a raised portion will occur between the magnetic head and the magnetic head during operation, resulting in an abnormally high coefficient of friction. If the lubricant film is too thin, there will be localized areas where the lubricant film is absent or too thin, and the desired durability cannot be achieved.

The lubricant film formed by the method according to the present invention described above has a low concentration and is processed for a relatively long time, so it has an extremely uniform film thickness, and even a thin film has a sufficient thickness. It can exhibit durability, etc.

[Function] According to the magnetic recording medium according to the present invention, the contact friction force generated between the head and the magnetic recording medium is reduced.

Further, the lubricant film and the plasma polymerized protective film are firmly bonded. As a result, the surface of the recording medium can be maintained in good condition over a long period of use. Further, according to the method of the present invention, a magnetic recording medium suitable for the above magnetic tape device and magnetic disk device can be easily manufactured.

[Example] Examples of the present invention will be described below.

Example 1 A 3.5-inch aluminum substrate was plated with nickel-phosphorus. Next, a magnetic thin film made of chromium and cobalt alloy was laminated thereon by a sputtering method (a laminate). This was placed in a vacuum container with a capacity of ff13 (1) and evacuated to a predetermined filling pressure state. Then, argon gas was introduced to a pressure of 0.1 Torr.

Next, a high frequency power of 13.56 MHz and 200 W was supplied between the above-mentioned laminate and the facing electrode to generate argon plasma.

At the same time, dibenzyl 10II3 on a heating boat placed in the vacuum container was heated and evaporated to perform plasma polymerization for 30 seconds. As a result, a plasma-polymerized protective film having a uniform thickness of about 300 people was formed on the laminate, and this was taken out into the atmosphere. This laminate was placed in a small glass container with polyoxyethylene stearylamine ether, a nonionic surfactant possessing two 300n hydroxyl groups.2. It was placed in a glass container (e) and sealed to allow some air to enter and exit. This was heated in a constant temperature bath at 100° C. for 3 hours to form a lubricant film. The elemental ratio of the plasma-polymerized protective film of the magnetic recording medium thus obtained was investigated: carbon: 1, hydrogen: 0.9, oxygen: 0.2.
The ratio was 6.

Furthermore, by bringing a magnetic head into contact with this magnetic recording medium, 1
A load of 0 g was applied and the dynamic friction coefficient was measured by rotating at a rotational speed of 90 rpm. The value of the kinetic friction coefficient after 3 minutes is 0.21, and the value of the kinetic friction coefficient after 1 hour is also 0.2.
It was 1.

Example 2 Cyclohexane (liquid) in place of dibenzyl in Example 1
The ratio of the elemental components of the plasma polymerized protective film was 1 for carbon, 1.4 for hydrogen, and 0.2 for oxygen. Also,
The coefficient of dynamic friction of the magnetic recording medium of Example 2, which was determined in the same manner as in Example 1, was 0.42.1 for 3 minutes and 0.42 for 1 hour.
It was 66.

Example 3 A magnetic recording medium was produced in the same manner as in Example 1, using benzene instead of dibenzyl. The ratio of the elemental components of the plasma polymerized protective film of this magnetic recording medium was 1 carbon, 1 hydrogen, and 0.22 oxygen. In addition, the dynamic friction coefficient of the magnetic recording medium of Example 3 measured in the same manner as Example 1 is as follows:
The 3-minute value was 0.35. The 1-hour value was 0.54.

Comparative Example 1 Comparative Example 1 was a sample obtained by performing the steps up to the production of a plasma polymerized protective film in the same manner as in the examples. The coefficient of dynamic friction of this Comparative Example 1 product was 1 or more in both the 3-minute value and the 1-hour value.

Comparative Example 2 A magnetic recording medium of Comparative Example 2 was prepared in the same manner as in Example 1, except that butyl stearate, a compound having no hydroxyl group, was used in place of polyoxyethylene stearylamine ether. The coefficient of dynamic friction of this magnetic recording medium was 0.42.1 hours for 3 minutes and 1 or more.

Examples 4 to 6 The magnetic recording medium of Example 4 was produced by using polyoxyethylene stearyl ether having one hydroxyl group in place of the polyoxyethylene stearylamine ether of Example 1, and also using polyoxyethylene stearyl ether having one hydroxyl group. The magnetic recording medium of Example 5 was prepared using stearic acid monoglyceride, and further, stearyl sorbitate was used to prepare the magnetic recording medium of Example 6.
A magnetic recording medium was fabricated. The dynamic friction coefficients of these magnetic recording media were as shown in Table 1 below.

Example 7 The steps up to the preparation of the plasma-polymerized protective film of Example 1 were carried out in the same manner, and polyoxyethylene stearylamine ether was dissolved in ethanol at 0.02% by weight, coated with a spin cord, and dried to form a magnetic recording medium. I got it. The coefficient of dynamic friction of this magnetic recording medium is also listed in Table 1 below.

Example 8 Instead of heating at 100° C. for 3 hours in a constant temperature bath as in Example 1, the medium was left indoors for 4 months to obtain a magnetic recording medium. The coefficient of dynamic friction of this magnetic recording medium is also listed in Table 1 below.

Table 1 As described above, the magnetic recording medium of the example can reduce the contact friction force generated between the head and the magnetic recording medium, and also has a strong bond between the lubricant film and the plasma polymerized protective film, so that it can be used repeatedly. The surface condition of the recording medium can also be maintained well by using. Therefore, it is extremely suitable for magnetic tape devices and magnetic disk devices.

[Effects of the Invention] As explained above, according to the magnetic recording medium and the manufacturing method thereof according to the present invention, a magnetic recording medium that is excellent in friction resistance and durability and can exhibit extremely good magnetic properties can be obtained. It can be easily provided.

Claims (2)

[Claims] (1) A magnetic recording medium comprising a magnetic film, a protective film, and a lubricant film sequentially laminated on a substrate, wherein the lubricant film is formed of a nonionic surfactant. (2) A step of forming a magnetic film on a substrate, a step of forming a plasma polymerized film on the magnetic film, and a step of forming the plasma polymerized film and the magnetic film in a gas containing a nonionic surfactant and oxygen. A method for manufacturing a magnetic recording medium, comprising the step of exposing the provided substrate to form a lubricant film on the plasma polymerized film.