JPS60127521A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance durability by applying a fluoroolefin copolymer type solvent-soluble fluororesin to the surface of a thin magnetic metal formed on the surface of a nonmagnetic base and forming a protective film low in friction, coefft. and high in adhesion to the magnetic layer. CONSTITUTION:A thin magnetic metal layer 5 of Co or Co-Ni alloy or the like is formed on a base 4 of a polyester or polyimide sheet, etc. and then, it is coated with a coating soln. prepd. by dissolving a fluoroolefin copolymer and a solvent-soluble type fluororesin, such as ''Lumiflon'' made by ASAHI GLASS KK dissolved in ethyl acetate or the like, and dried to form a protective layer 6 in the range of 5-100nm thickness. In addition, the magnetic layer 5 is vapor deposited under the presence of slight amt. of O2 to slightly oxidize is surface, resulting in enhancing adhesion to the protective layer 6 and obtaining a magnetic recording medium much more enhanced in durability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to improvements in magnetic tapes for audio, video, etc. in the field of magnetic recording.

Conventional configurations and their problems In recent years, the field of magnetic recording has progressed toward higher density recording, and the magnetic tapes used have changed from the conventional coated magnetic tape to metal thin film magnetic tape, which is advantageous for high-density recording. Technological innovations are being made to the use of tape.

A conventional metal thin film type magnetic recording medium will be explained below. Hereinafter, the metal thin film type magnetic recording medium will be referred to as a magnetic recording medium.

FIG. 1 shows a cross-sectional view of a conventional magnetic recording medium, and numeral 1 indicates the substrate of the magnetic recording medium, which is a polymer film. 2
is a magnetic layer, which is made of an oxide film of Go, CoNi alloy, GoOr alloy, Fe2O, etc. +114. 3 is a protective film coated on the surface of the magnetic layer to improve durability. Higher fatty acids are used as the protective film for No. 3, such as myristic acid.

Palmitic acid, stearic acid, etc. alone or in mixtures were used.

However, with the above configuration, the adhesion strength of the surface protective layer was weak, and the durability was not sufficiently improved. The purpose of the surface protective layer is to lower the coefficient of friction of the magnetic recording medium, and when the magnetic tape is repeatedly used as a magnetic tape, such as a video tape, damage caused by sliding between the magnetic head and the post for running the tape is prevented. The aim is to improve durability during repeated use.

In particular, since the surface of the magnetic layer of the metal thin film is entirely made of metal and has a large coefficient of friction compared to coated recording media, it has been coated with higher fatty acids, which are commonly used as lubricants. This material was able to lower the coefficient of friction.

For example, in a magnetic material using Co' metal, the coefficient of friction was 0.5, but when myristic acid was applied in a film thickness of 50°, it was possible to lower it to 0.3i. however,
The magnetic layer and the higher fatty acid were weakly adsorbed unless they were particularly heat-treated at 100° C. or higher, and they would separate if they were repeatedly slid with a post or the like. Furthermore, if the magnetic layer and higher fatty acid salts are formed by heating at 100"C or higher to create strong adsorption, durability can be improved, but this is difficult because the substrate film is a polymer film.

OBJECT OF THE INVENTION The present invention solves the above-mentioned problems of the conventional art, and provides an atomizer that improves the durability of audio tapes and video tapes during repeated use by realizing strong adhesion strength and a low coefficient of friction. It provides a recording medium.

Structure of the Invention The present invention is a metal thin film type magnetic recording medium in which a solvent-soluble fluororesin based on a fluoroolefin copolymer is coated on the surface of a magnetic layer.

This can improve durability when used repeatedly as an audiotape or videotape.

DESCRIPTION OF EMBODIMENTS An embodiment of the implanted invention will be described with reference to the drawings.

FIG. 2 is a diagram showing the basic configuration of a magnetic recording medium in an embodiment of the present invention. In FIG. 2, 41 is the substrate of the magnetic recording medium, 5 is the magnetic layer, and 6 is the protective layer.

A polymer film is used as the substrate 4, and the magnetic layer 5 is formed by heating and melting a magnetic metal in a vacuum, turning it into vapor, and adhering it to the substrate to form a magnetic metal thin film. After that, the protective film is formed, and the formation method is to dissolve the fluoroolefin copolymer-based solvent-soluble fluororesin and the curing agent in a solvent, apply it to the surface of the magnetic layer using a reverse coater or gravure coater, and then dry it. Then, the resin is cross-linked at medium temperature to complete the protective film.Here, the substrate 4 is polyethylene terephthalate 1.
, polyamide, polyimide, acetate, etc. The magnetic layer 5 is made of Go, CoNi alloy, Co
The protective layer 6, which is appropriately selected from Cr alloy, Fe, O3 oxide, is formed by a solvent coating method.
Reverse coater, gravure coater.

The method is appropriately selected from among depping, spraying methods, etc.

The substrate of the magnetic recording medium is mainly made of polyethylene terephthalate, and has a thickness of about 50 μm to 1 μm. In particular, the board needs to have strong mechanical strength.
A material having a Young's modulus of 4ooKg/- or more is used.

CoNi alloy is mainly used for the magnetic layer, and the film thickness formed by vacuum evaporation is in the range of 1000 to 2000 nm. The magnetic layer contains oxygen during vapor deposition and controls the coercive force using magnetic properties, but the appropriate value for a magnetic recording medium is 6000. ~15,000 (5), and a residual magnetic flux density of about 10,000 Gauss to 3,000 Gauss is used.

The thickness of the protective layer used is in the range of 1000 to 60 layers. The intention behind this is that a thick protective layer will keep the coefficient of friction stable and improve durability, but when performing magnetic recording and reproduction,
This results in gap loss, resulting in a decrease in reproduction output and deterioration in performance. Therefore, the thickness of the protective layer needs to be thinner than a certain thickness. If the protective layer is thin, the durability will deteriorate, and the lower limit is determined based on practical characteristics.

The protective layer may be applied by dissolving the resin alone in a solvent, but by adding a curing agent and crosslinking, the protective layer strongly adheres to the magnetic layer.

When the magnetic recording medium configured as described above is used as a magnetic tape for video, the magnetic head, the post for running the tape, and the tape surface slide, and the sliding part of the present invention Since the protective layer has a small coefficient of friction and is not chipped during sliding, the tape surface does not easily become smudged by repeated running of the tape, improving durability.

A more specific embodiment of the present invention will be described below.

The material used for the substrate of the magnetic recording medium is polyethylene terephthalate, and a smooth film with a thickness of 16 μm is used. A magnetic layer is formed on the substrate by an oblique evaporation method while the substrate is placed in a vacuum chamber and brought into contact with a cooling can. Material of magnetic layer: VJ, -CoNi alloy Go8
0%, Ni 20%, and a micro pressure of 1 was used during vapor deposition.
x 10' Torr (7) Maintain in O2 atmosphere.

A protective layer is formed on the surface of the magnetic recording medium thus formed.

Fluoroolefin copolymer solvent-soluble fluororesin d
: There is [Lumiflon] sold by Asahi Glass Co., Ltd., and the grades are LFloo, LF200°LF3○
There is 0. An example of use as a protective film is LFloo.
was dissolved in acid-resistant ethyl to a concentration of 100 ppm,
This solution is applied to a thickness of 20 μm using a reverse coater or the like and dried to obtain a protective film of 200 μm. The effect of the magnetic recording medium thus obtained is shown in FIG. In FIG. 3, the horizontal axis indicates the number of times reproduction is repeated after one recording when used as a videotape, and the vertical axis indicates the reproduction output level, expressed in decibels (bB).

A is the magnetic recording medium shown in the example, and B is the magnetic recording medium shown in the conventional example, with 200 layers of myristic acid formed in the protective layer.

As shown in Figure 3, the conventional product 1J', iOOlI+
Although the output decreases with one repeated reproduction, the magnetic recording medium of the present invention shows no decrease in output even after 300 repetitions. According to this embodiment, the durability of the magnetic tape can be improved by forming a fluoroolefin copolymer solvent-soluble fluororesin film on the magnetic layer surface of the magnetic recording medium.

Although the present example specifically showed the effect, it was confirmed that the combination of the other materials mentioned above constituting the present invention also had the same effect.

Effects of the Invention As described above, the present invention achieves a low coefficient of friction by providing a metal thin film magnetic recording medium characterized by coating the magnetic layer surface with a fluoroolefin copolymer-based solvent-soluble fluororesin. By implementing the present invention, it is possible to provide a magnetic recording medium that improves the durability of audio tapes and video tapes during repeated use, and the practical effects thereof are significant.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a conventional metal thin film magnetic recording medium.
FIG. 2 is a sectional view showing a metal thin film magnetic recording medium in an embodiment of the present invention, and FIG. 3 is a characteristic diagram showing the effects of the present invention. 1...Substrate, 2...Magnetic layer, 3...
...Protective film, 4...Substrate, 6...Magnetic layer, 6...Protective film. Name of agent: Patent attorney Toshio Nakao and 1 other M1
Figure 2 Figure 3 θ /ρσ IQQ Jρρ

Claims (1)

[Claims] A magnetic recording medium characterized in that a fluoroolefin copolymer-based solvent-soluble fluororesin is coated on the surface of a metal thin film magnetic layer.