JPS6284421A - Thin metallic film type magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve a slitting characteristic by forming a magnetic recording layer having at least a thin ferromagnetic metallic film layer on one face of a high-polymer film and providing a nonmagnetic layer satisfying specific conditions on the opposite face thereof. CONSTITUTION:The magnetic recording layer having at least the thin ferromagnetic metallic film layer is formed on one face of the high-polymer film and the nonmagnetic layer satisfying the conditions expressed by the equation is provided on the opposite face thereof. The thin ferromagnetic metallic film layer 3 essentially consisting of cobalt is formed by a vapor deposition method on one face of, for example, a polyethylene terephthalate film 1 and an overcoat layer 3 essentially consisting of silicon is coated atop the same. On the other hand, a thin manganese film is formed as the nonmagnetic layer 4 on the opposite face of the film 1 and a back layer 5 consisting of carbon and binder is formed by coating atop side layer. Slitting is thus made possible without partial deformation of the high-polymer film by the force of a slitting blade and without cracking the thin ferromagnetic metallic film layer and the flatness of a medium is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a metal thin film type magnetic recording medium having excellent slitting properties, durability, and the like.

BACKGROUND OF THE INVENTION In recent years, in order to improve recording density, metal thin film magnetic recording media formed by thin film forming means such as vapor deposition, sputtering, and ion blating have been actively developed and studied. Improving recording density is not just a necessity for high integration in an information-oriented society, but is also necessary from the perspective of improving performance such as sound quality and image quality during recording and playback, and improving reliability such as durability. , is a subject to be pursued forever.

An example of a conventional metal thin film magnetic recording medium will be described below with reference to the drawings.

FIG. 2 shows a cross-sectional structure of a conventional metal thin film magnetic recording medium. In FIG. 2, 1 is a polymer film as a base material, 2 is a ferromagnetic metal thin film layer, and 3 is an overcoat. This magnetic recording medium has a magnetic recording layer made by depositing a ferromagnetic metal such as cobalt on one side of a polymer film 1 by vapor deposition, and a silicon-based overcoat is formed on the top surface for the purpose of lubricity and rust prevention. It is something.

Problems to be Solved by the Invention However, in the above configuration, (1) the elastic modulus and hardness of the ferromagnetic metal thin film layer 2 are thicker than the elastic modulus and hardness of the polymer film 1; During slitting, a portion of the polymer film 1 is deformed, resulting in poor flatness and durability, and level fluctuations are likely to occur.

(2) Cracks are likely to occur in the ferromagnetic metal thin film layer 2, and detachment of the ferromagnetic metal thin film layer 2 is likely to occur, resulting in dropouts and the like.

It had problems such as.

In view of the above problems, the present invention provides a metal thin film magnetic recording medium with improved slitting performance. The recording medium has a structure in which a magnetic recording layer having at least a ferromagnetic metal thin film layer is formed on one side of a polymer film, and a nonmagnetic layer satisfying the following conditions is provided on the opposite side.

t 0.7<-<12 EOl.

Here, Eo is the elastic modulus of the ferromagnetic metal thin film layer, to is the thickness of the ferromagnetic metal thin film layer, E is the elastic modulus of the nonmagnetic layer, and t is the thickness of the nonmagnetic layer.

Effect of the present invention With the above-described configuration, the force of the slitting blade is applied almost uniformly to both sides of the polymer film, making it possible to slit the polymer film without deforming a part of the polymer film, and preventing cracks or the like in the ferromagnetic metal thin film layer. Therefore, the flatness of the medium is also improved.

EXAMPLES Hereinafter, the metal thin film magnetic recording medium of the present invention will be explained with reference to the drawings of examples.

FIG. 1 is an embodiment of the present invention, and shows the cross-sectional structure of a metal thin film magnetic recording medium.

In FIG. 1, 1 is a polyethylene terephthalate film as a paste material, 2 is a ferromagnetic metal thin film layer, 3 is an overcoat layer, 4 is a nonmagnetic layer, and 6 is a back layer.

A 0.2 μm thick ferromagnetic thin film layer 3 mainly composed of cobalt is formed on one side of the polyethylene terephthalate film 1 by vapor deposition. The value of To is 0, 42
108 dyn/CB), an overcoat layer 3 mainly made of silicon was applied to the upper surface of the film, and a 0.15 μm thick manganese thin film was formed by vapor deposition on the opposite surface of the polyethylene terephthalate film 1. Sample A was obtained by applying a back layer 6 made of carbon and a binder to the top surface of the non-magnetic layer 4.

Similarly, the nonmagnetic layer 4 was made of manganese with a thickness of 0.14 μm, chromium with a thickness of 0.2 μm, titanium with a thickness of 0.2 μm, and titanium with a thickness of 0.2 μm.
Samples B, C, D, and E made of 0.2 μm copper were obtained.

3. These samples A-E. It was slit into a 1mm width, rolled into an audio half, and evaluated in a 30-pass endurance test of 46 minutes per pass in an audio cassette deck at a temperature of 60℃ and a humidity of 30%.The table below shows the results. show.

As shown in the table above on page 6 and 7, according to this example (samples A and C), almost the same ET as the ferromagnetic metal thin film was deposited on the opposite side of the polymer film.
By providing a nonmagnetic layer by depositing manganese and chromium by vapor deposition so as to achieve a certain value, it is possible to improve the flatness of the medium and reduce the occurrence of level fluctuations and dropouts.

Therefore, the force of the slitting knife does not deform part of the polymer film, and no cracks occur in the ferromagnetic metal thin film layer.
This means that the flatness of the medium has also been improved.

In other words, in a metal thin film type magnetic recording medium, if the difference in elastic modulus or hardness between the ferromagnetic metal thin film layer and the polymer film is too large, the ferromagnetic metal thin film will be attached to the flexible polymer film with a low elastic modulus during slitting. This is because a larger force is applied to the layer, causing a portion of the polymer film to deform.

In the examples, the magnetic recording layer is a ferromagnetic metal thin film layer mainly composed of cobalt, but it is similar to the conventional example.

Effects of the Invention As described above, the present invention provides a non-magnetic layer that satisfies the requirements for magnetic recording R+, which has at least a ferromagnetic metal thin film layer on one side of the polymer film, by vapor deposition. It can be slit without deforming the ferromagnetic metal thin film layer, and without causing cracks in the ferromagnetic metal thin film layer.It is highly reliable in terms of flatness and running resistance of the medium, and it also prevents level fluctuations and dropouts. Therefore, it is possible to realize a metal thin film magnetic recording medium with very few materials.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram of a metal thin film magnetic recording medium according to an embodiment of the present invention, and FIG. 2 is a cross-sectional structural diagram of a conventional metal thin film magnetic recording medium. 1...Polyethylene terephthalate film,
2...Ferromagnetic metal thin film layer, 3...Overcoat layer, 4...Nonmagnetic layer, 5...
・Back coat layer.

Claims (1)

[Scope of Claims] Metal thin film type magnetic material, characterized in that a magnetic recording layer having at least a ferromagnetic metal thin film layer is formed on one side of a polymer film, and a nonmagnetic layer satisfying the following conditions is provided on the opposite side. recoding media. 0.7<Et-E_0t_0<1.2 where E_0 is the elastic modulus of the ferromagnetic metal thin film layer, t_0 is the thickness of the ferromagnetic metal thin film layer, E is the elastic modulus of the non-magnetic layer, and t is the elastic modulus of the non-magnetic layer. It is the thickness.