JPS60111322A - Thin metallic film type magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a medium which does not crack even after repetitive recording and reproducing or is usable with substantially no decrease in S/N even if a crack arises in the medium by maintaining the compressive modulus of a high polymer base plate in the thickness direction thereof in a specific range. CONSTITUTION:A high polymer base plate 2 is exemplified by polyester, polyolefin, cellulose deriv., polycarbonate, PVC, polyamide, polyimide, etc. and in the case of having an undercoating layer, said layer regarded inclusively as the plate 2. A limitation is given to the mechanical characteristic of the plate 2 in the thickness direction thereof. More specifically, the compressive modulus in the thickness direction is made >=400kg/mm.<2>. Cracking is thereby obviated even in the abnormal stress concentration in a traveling system and even if the medium is cracked, the crack is not developed to the permanent set to the extent of decreasing S/N. The selection of the material having >=400kg/mm.<2> compressive modulus in the thickness direction as the conditions for the base plate is accomplished by selecting material or selecting particularly the conditions for heat managing in the stage of forming the film even if the same material is used.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a metal thin film magnetic recording medium used for high-density magnetic recording and reproduction.

Conventional configurations and their problems In magnetic recording media used for video recording, computer data recording, etc., there is a strong desire to improve recording density in order to achieve larger recording capacities and miniaturization of equipment. well known.

For this reason, magnetic recording media continue to be improved in various fields, but magnetic recording and reproduction is based on the interaction between the medium and the magnetic head, and it goes without saying that in principle it is a medium suitable for high-density recording. , it must be possible to ensure practical reliability.

- Considering the circumstances of the article, the currently proposed C, o -Ni
Metal thin film magnetic recording media, whose magnetic recording layer is a ferromagnetic metal thin film such as -0 series in-plane magnetization film or Go-Or thread perpendicular magnetization film, have shortest recording wavelengths as short as 0.5 μm. Although it has been confirmed that magnetic recording is possible and is viewed as promising, it has the disadvantage that the ferromagnetic metal thin film cracks during repeated use, increasing the signal-to-noise ratio (hereinafter referred to as S/N). Attempts have been made to apply a lubricant to the surface of the layer to impart lubricity, thereby dispersing stress and suppressing the occurrence of cracks, but this is insufficient and also reduces the adhesion between the ferromagnetic metal thin film and the polymer substrate. Pre-treatment of polymer substrates based on the idea that strength is an important factor has been tested, but this is still insufficient.For example, in recording and reproducing using a rotating magnetic head, We devised a tape running system,
Even if the magnitude and variation of the tension applied to the tape is reduced, 1
The reality is that it is impossible to find a configuration that can hold S/N more than 00 times.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a metal thin film type magnetic recording medium which uses a ferromagnetic metal thin film as a magnetic recording layer and has a stable S/N when used in a recirculating manner.

Structure of the Invention The metal thin film type magnetic recording medium of the present invention is characterized in that the compressive elastic modulus in the thickness direction of the polymer substrate is 4.0 OK9/- or more, and the magnetic recording medium is characterized in that the compressive elastic modulus in the thickness direction of the polymer substrate is 4.0 OK9/- or more. In this case, it is possible to obtain a medium that can be used without any cracks or with almost no decrease in S/H even if cracks do occur.

DESCRIPTION OF EMBODIMENTS The present invention will be described below with reference to the drawings. 1st
The figure is an enlarged cross-sectional view of the metal thin film magnetic recording medium of the present invention.
In FIG. 1, 1 is a magnetic recording layer made of a ferromagnetic metal thin film, 2 is a polymer substrate, and 3 is a lubricant coating layer. Here, as the ferromagnetic metal film 1, Go, Fe, Ni
, Go-Fe, Go-Ni, Go-B
.

Co-Cu, Go-Ge, Co-Mn,
GO-'Mg, Go-Mo.

Go-Pt, Co-Ru, Go-Rh, Co-8i, G
o-8m.

Go-G4. Co-Ta, Go-V, Go-W, Go-
Y.

00-Zn, Go-Or, Go-Ti,
, Go-Ce, Go-Ni-Or, G
Examples include o-Ni-Mg and their partial oxide films and partial nitride films.

Methods for producing the thin film include non-removal plating, ion beam deposition, and ion plating.

It can be appropriately selected from known thinning techniques such as spankling and electron beam evaporation.

As the polymer substrate 2, polyethylene terephthalate l-
etc., polyolefins such as polypropylene, cellulose diacetate, cellulone conductors such as 21-cellulose, polycarbonate 1-, polyvinyl chloride, polyamide, polyimide, etc., and when it has an undercoat layer. shall be considered including the polymer substrate 2. The lubricant coating layer 3 contains fatty acids, metal soaps, fatty acid amides, mineral oils, animal and vegetable oils, and higher alcohols.

It is obtained by dissolving silicone oil and fluorocarbon 1K4fx in a solvent, coating and drying, and is obtained by a dry method.

The gist of the present invention is to add a limit to the mechanical properties of the substrate in the thickness direction, which have not received any attention in the past. Kg / 2" or more, as will be described later, will prevent cracks from occurring even if abnormal stress concentration occurs in the running system, but even if they do occur, they will not cause permanent deformation to the extent that the S/N will decrease. .

Although it is not necessarily clear that the critical value is 400 Kg/,7, the premise is that for short wavelength recording, the surface of the magnetic recording layer has an average roughness of 0.05μ.
Since it is preferably used for tapes of less than m, special consideration has been given to the tape running system, such as cylinders and posts.

The surface finish of pinch rollers, guide pins, etc. is also used at 18 or less, so the combination of these is comprehensively determined, and the tape tension during steady running can be up to 40 knots (lined up in a tape width of 8 m). It is assumed that the substrate is used within a range of 2 μm or less in thickness.

Furthermore, numerous experimental results have shown that 400 and 9i-
In the range from 300 Kg/,j to 300 Kg/,j, there is a range where the S/N deteriorates in some cases and in others does not depending on the conditions of the ferromagnetic metal thin film, so it is preferable to use 400 Kg/,4 or less.

In addition, in order to select a substrate with a compressive modulus of elasticity of 400 Kg/1 or more in the thickness direction, it is possible to select a substrate that has a compressive elastic modulus of 400 Kg / 1 or more in the thickness direction, or to select a substrate that has the same material but by selecting particular heat management conditions during film formation. It is.

[Example-1] A polyetherketone sulfone film with a thickness of 15 μm was selected from three levels of compressive elastic modulus in the thickness direction, and Go-Ni (Ni 20% by weight) o and 12 m were placed on the substrate.
0.2 μm/m in oxygen atmosphere of 10”” Torr
It was deposited with a minimum angle of incidence of 43 degrees at a rate of in.

A methyl ethyl ketone cloth containing 180 ppm of myristic acid dissolved therein was placed on top of this to obtain a magnetic tape of s mb width.

This tape was attached to an Amorph 1 head with a gap length of 25 μm and a diameter of 40 m. The test video tape recorder, which has a running system that moves along the rotating cylinder of the
We investigated changes in N. S/N is recording wave 0.66μm
The value at the first recording/reproduction was set as o[dB:]. The results are shown in Table 1.

Margin below [Example-2] A polyamide-imide film with a thickness of 9 μm was used as a substrate, and N' of 80% N1 was used as a substrate, and the compressive modulus of elasticity in the thickness direction was different.
i-Fe alloy 0.3 μm, 20% cr CO-Cr
A layer of 0.1 μm of the alloy was laminated by the puttering method using a glow discharge of 13.56 Mllz in an Ar partial pressure of 1×10″'2 Torr, and 8 layers for perpendicular recording were prepared in the same manner as in Example-1. Create a tape with a gap length of 0.
Table 2 shows the results of examining changes in S//N using a 3 μm ferrite head.

Below Margin Common to both examples is that irrespective of the substrate, if the compressive elastic modulus in the thickness direction is 400 Kq, '/- or more, the S/N will be maintained regardless of the environment and even after repeated use. As shown in Fig. 2 which schematically shows the cracking mechanism, this is because the abnormal protrusion 6 of the post 4 does not change much.
(Also, the same applies to the case of hard dust, magnetic powder, etc.) which causes deformation in the thickness direction of the board (arrow A).
(as shown in ) propagates and ruptures the ferromagnetic metal thin film,
Cracks 6 hardly occur, or even if they occur, the deformation m is small and does not affect S/H. This type of crack is characterized by radial cracks or a mixture of radial and nearly concentric cracks, and since this type of crack generates significant noise, the structure of the present invention prevents this from occurring during repeated use. N
This is extremely effective in obtaining a magnetic recording medium with stabilized magnetic properties.

Effects of the Invention The present invention provides a polymer substrate with a compressive modulus of elasticity of 400 in the thickness direction.
By placing a ferromagnetic metal thin film on a substrate of Kq/- or more, it is possible to practically prevent cracks from occurring and reducing the S/N when used repeatedly in a tape recorder. It has great practical value as a recording medium.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of the metal thin film magnetic recording medium of the present invention, and FIG. 2 is a diagram for explaining the effects of the magnetic recording medium of the present invention. 1...Ferromagnetic metal thin film, 2...Polymer substrate, 6...Crack portion.

Claims (1)

[Claims] A magnetic recording medium comprising a magnetic recording layer made of a ferromagnetic metal thin film arranged on a polymer substrate, characterized in that the compressive modulus of elasticity in the thickness direction of the polymer substrate is 400 Ky/- or more. Metal thin film magnetic recording medium.