JPH02126417A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve durability and reliability by successively forming a thin ferromagnetic metallic film, a hard carbon film, a nitrogenous plasma- polymerized film, and a lubricating agent layer contg. fluorine-contained carboxylic acid on a nonmagnetic base. CONSTITUTION:The thin ferromagnetic metallic film, the hard carbon film 3, the nitrogenous plasma-polymerized film 4, and the lubricating agent layer 5 contg. the fluorine-contained carboxylic acid are successively formed on a substrate 1. A polyethylene terephthalate film, other polyesters and polyolefins and other plastic films are usable for the substrate 1. A nonmagnetic metallic substrate is equally usable. Fe, Co and Ni or the alloys composed thereof are usable for the thin ferromagnetic metallic film 2. The film 3 can be formed by plasma discharge or sputtering of gaseous hydrocarbon. The film 4 can be formed by plasma discharge of a nitrogen compd. The film 5 can be formed by application of a soln. contg. the lubricating agent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a ferromagnetic metal thin film magnetic recording medium suitable for high-density magnetic recording media. The present invention relates to a magnetic recording medium that uses a metal thin film as a magnetic recording layer.

Conventional technology In the field of magnetic recording, performance improvements such as digitization, miniaturization, and longer recording times have been progressing in recent years.

Along with this, the demand for high-density magnetic recording media has increased.
Magnetic recording media in which the magnetic recording layer is composed of a ferromagnetic metal thin film are being actively studied because they are extremely advantageous for short wavelength recording.

However, in a ferromagnetic metal thin film type magnetic recording medium,
Because the surface of the magnetic layer has extremely good surface properties, durability, runnability, and corrosion resistance are greatly affected by friction and wear caused by high-speed sliding with the magnetic head during the recording and reproducing process of magnetic signals. Improvements have become a major issue.

Therefore, a top coat layer is provided on the surface of the magnetic layer.

Attempts have been made to improve the durability, runnability, and corrosion resistance.

For example, formation of a vapor-deposited film of fatty acid metal salt (Japanese Patent Application Laid-Open No. 1989-1999)
113303), formation of sputtered films of polymers having imide groups (JP-A-57-116771), sputtered films using polymers as targets, carbon, BN,
Formation of a diamond-like hard carbon film made by sputtering or vapor deposition of MoS, , SiO□, etc. (Japan Society of Applied Magnetics, 46th research meeting materials), formation of a lubricating layer of fatty acids, fatty acid amides, etc. (for example, 56-306
Many attempts have been made, including Publication No. 09).

However, in the above-mentioned examples, durability, runnability, corrosion resistance, etc. cannot be fully satisfied, so the idea of laminating them and sharing their respective roles is increasing.

one in which a fluorocarbon-based lubricating layer is formed on an adsorption layer of fatty acid metal salt (Japanese Patent Application Laid-open No. 120331/1983);
One in which a fluorine-containing lubricating oil is placed on a hard carbon layer (Japanese Unexamined Patent Publication No. 126627/1982), and one in which a lubricant layer is formed on a 5i-N-0 thin film (Japanese Unexamined Patent Publication No. 61-1312).
Publication No. 31).

Problems to be Solved by the Invention However, even with the above-described configuration, the requirements regarding the durability of the magnetic recording medium are severe, and the characteristics cannot be said to be sufficient, and improvements in the layers are still desired.

The present invention solves the above problems and has excellent durability.
The purpose is to provide a highly reliable magnetic recording medium.

Means for Solving the Problems In order to solve the above problems, one magnetic recording medium of the present invention includes:
Hard carbon film, nitrogen-containing plasma polymerized film on ferromagnetic metal film,
A lubricant layer containing a fluorine-containing carboxylic acid is sequentially formed.

Effect: With the above structure, the lubricant layer containing fluorine-containing carboxylic acid can uniformly and firmly cover the hard carbon film via the nitrogen-containing plasma polymerized film, so a sufficient lubricating effect can be achieved with a small amount of lubricant. Moreover, the hard carbon film can also be made thinner.

As a result, excellent durability can be obtained without suffering a significant spacing loss, and extremely high reliability can be ensured.

EXAMPLE Hereinafter, a magnetic recording medium according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a magnetic tape which is an embodiment of the magnetic recording medium according to the present invention. In Figure 1,
1 is a substrate serving as a nonmagnetic support plate; 2 is a ferromagnetic metal thin film formed on the substrate 1; 3 is a hard carbon film, and 4 is a nitrogen-containing plasma polymerized film.

Reference numeral 5 denotes a lubricant layer containing a fluorine-containing carboxylic acid, which is successively formed on the ferromagnetic metal thin film 2.

Although a polyethylene terephthalate film is often used as the substrate 1, it may also be a plastic film made of other polyesters, polyolefins such as vopropylene, cellulose derivatives such as cellulose acetate, polyamide, polyimide, etc., or a nonmagnetic metal substrate. It may be.

In addition, ferromagnetic metal thin [2] is iron, cobalt, nickel, or alloys mainly composed of iron, cobalt, nickel, or their partially oxidized films formed by electron beam evaporation, sputtering, ion blating, or electroless plating. , a partial nitride film, etc. can be used.

Further, the hard carbon film 3 can be formed by plasma of a hydrocarbon gas or sputtering of carbon or graphite in an inert gas or an atmosphere of an inert gas and a hydrocarbon gas.

When the hard carbon film 3 is formed by hydrocarbon gas plasma, hydrocarbon gas or a mixed gas of hydrocarbon gas and inert gas is introduced into the vacuum container, and the
While maintaining the pressure of 1 Torr, a discharge is made inside the vacuum container to generate hydrocarbon plasma and form a hard carbon film 3 on the surface of the substrate 1. The discharge type may be either an external electrode type or an internal electrode type, and the discharge frequency can be determined experimentally. Also,
By applying a voltage of O to -3 to V to the electrode on the side of the substrate 1, the hardness of the film can be increased and the adhesion can be improved. As the hydrocarbon, methane, ethane, propane, butane, etc. can be used.

Further, in order to form a hard carbon film, it is preferable to increase the discharge energy as much as possible. Further, it is desirable that the temperature of the substrate 1 is also as high as possible.

On the other hand, sputtering methods include direct current sputtering, alternating current sputtering, high frequency sputtering, magnetron sputtering, ion beam sputtering, etc., and any method may be used. In order to form a hard film, the pressure is preferably 0.01 Torr;
Also, it is better to have a high energy density, for example,
In high frequency magnetron sputtering, I per target area
W/d or more is preferable, and by sputtering while applying a voltage of 0 to -3 V to the electrode on the side that holds the substrate 1, the hardness and adhesion of the film can be increased similarly to plasma. be able to.

The nitrogen-containing plasma polymerized film 4 is formed by introducing a nitrogen compound into a vacuum container and generating plasma by discharging it inside the vacuum container while maintaining a pressure of 0.001 to I Torr. The discharge type may be either an external electrode type or an internal electrode type, and the discharge frequency can be determined experimentally.

The thickness of this nitrogen-containing plasma polymerized film 4 is preferably 100 Å or less, more preferably 50 Å or less.

As the nitrogen compound, dimethylamine, trimethylamine, diethylamine, triethylamine, isopropylamine, n-butylamine, pyridine, aniline, dimethylaniline, formamide, dimethylformamide, etc. can be used.

The fluorine-containing carboxylic acid has the general formula R, C0ol+ (however.

In the formula, R1 is a monocarboxylic acid represented by a perfluorophenyl group, a linear or branched perfluoroalkyl group, or a partially fluorinated alkyl group, or a compound of the general formula R,0
A partial carboxylic acid ester represented by OCRCOO11 (wherein R1 is a perfluorophenyl group, a linear or branched perfluoroalkyl group, or a partially fluorinated alkyl group), or a perfluorinated carboxylic acid group having a terminal carboxylic acid group. Fluoropolyether and the like can be used. These fluorine-containing carboxylic acids may be used alone as a lubricant, or may be used in combination with other lubricants.

Furthermore, as lubricants, fatty acids, fatty acid esters, fatty alcohols or their alkoxides, polyhydric alcohols or their esters, sulfurized fatty acids, aliphatic mercaptans, modified silicone oils, perfluoropolyethers, higher alkyl sulfonic acids, One or more of perfluoroalkyl sulfonic acids, perfluoroalkyl carboxylic acid esters, carboxylic acid perfluoroalkyl esters, etc. can be used.

The lubricant layer 5 containing the fluorine-containing carboxylic acid can be formed on the nitrogen-containing plasma polymerized film 4 by a conventional coating method or by spraying a solution containing the lubricant. It is obtained by immersing it in this solution and drying it.

Further, the coating amount is preferably 0.1 to 2011 g/nf. If the coating amount is too small, the effects of lowering the friction coefficient and improving durability and wear resistance will not be achieved.

If the amount is too large, a sticking phenomenon will occur between the sliding member and the magnetic recording medium, which will actually worsen running performance.

Next, the present invention will be described in more detail while comparing Examples and Comparative Examples.

Example 1 Co was diagonally deposited on a polyethylene terephthalate film with a thickness of 10 μm using an electron beam method, and the film thickness was 1500 μm.
-Ni-0 film was formed. Next, 150 people formed a hard carbon film under the following sputtering conditions. The conditions were such that carbon was used as a target and sputtered by high frequency magnetron sputtering in an Ar atmosphere to form a hard carbon film. The Ar gas pressure was 0.003 Torr, and the input power density was 2.51/d.

Then, while introducing diethylamine, the temperature was increased to 0.2 Torr.
With r pressure, frequency becomes 3! A nitrogen-containing plasma polymerized film with a thickness of 30 people was formed under the conditions of 1z and 1001 oz of power.

Furthermore, C□Fl, CH, OOC(CI(,
) A fluorine-containing carboxylic acid partial ester represented by 2COOH was applied in a coating amount of 5111 g/rrr, and the tape was cut into a width of 8 m to prepare a magnetic tape.

Example 2 A magnetic tape was prepared in the same manner as in Example 1, except that pentadecafluorooctanoic acid was applied as a lubricant at a coating amount of 4 cm/I.

Example 3 As a lubricant, C, Fl, CI, 0OC(CH□), C
A magnetic tape was prepared in the same manner as in Example 1, except that the fluorine-containing carboxylic acid partial ester represented by 0OH was applied at a coating amount of 6 cm/I.

Example 4 As a lubricant, nonadecafluorodecanoic acid was applied in an amount of 3■
/Processed in the same manner as in Example 1 except that the coating was carried out under the conditions of
Created magnetic tape.

Example 5 A magnetic tape was prepared in the same manner as in Example 1, except that a perfluoropolyether having a carboxylic acid at the end was applied as a lubricant at a coating amount of 3/n.

Comparative Example 1 A magnetic tape was produced in the same manner as in Example 1 except that the nitrogen-containing plasma polymerized layer was not provided.

Comparative Example 2 A magnetic tape was prepared in the same manner as in Example 1, except that octyl pentadecafluorooctanoate was applied as a lubricant at a coating amount of 6 cm/I.

Comparative Example 3 A magnetic tape was produced in the same manner as in Example 1 except that the hard carbon film was not formed.

The magnetic tape obtained above was used as a commercially available 8 m VTR.
A still durability test was carried out using a testing machine with the same functions as 40℃, 5%R)I and 5℃, 80%R)I, and the time required for the playback output to initially decrease by 3dB was measured. It was measured. In addition, a running durability test was conducted by repeated playback, and a decrease in playback output after running 200 passes was measured.

These results are shown in Table 1.

Space below No. table In each example as shown in Table 1.

Still durability and running durability are extremely good.

No damage was observed on the tape surface even after running 200 passes. On the other hand, the tapes of each comparative example had short still durability, a large decrease in output after running durability, and low practical reliability.

Effects of the Invention As described above, according to the present invention, by sequentially forming a hard carbon film, a nitrogen-containing plasma polymerized film, and a lubricating layer containing a fluorine-containing carboxylic acid on a ferromagnetic metal thin film, one ferromagnetic metal thin film type We were able to dramatically improve the practical reliability of magnetic recording media.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a magnetic tape which is an embodiment of the magnetic recording medium according to the present invention. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Ferromagnetic metal thin film, 3...Hard carbon film, 4...Nitrogen-containing plasma polymerized film, 6...Lubricant layer. Agent Yoshihiro Morimoto

Claims (1)

[Claims] 1. A ferromagnetic metal thin film formed on a non-magnetic support, a hard carbon film sequentially formed on the ferromagnetic metal thin film, a nitrogen-containing plasma polymerized film, and a lubricant layer containing a fluorine-containing carboxylic acid. A magnetic recording medium consisting of