JPS60111320A - Thin metallic film type magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium which is free from decrease in S/N owing to the crack generated in repetitive use with a tape recorder by disposing a thin ferromagnetic metallic film having the Young's modulus equal to the Young's modulus of a high polymer base plate as a magnetic recording layer. CONSTITUTION:A thin ferromagnetic metallic film 1 which is a magnetic recording layer consists of Co, Fe, Ni, Co-Fe, Co-Ni, Co-B, Co-Cr-Sn, etc. and the partial oxide film thereof or partial nitride film and the Young's modulus of the thin film can be ajdusted by adding In, Sn, Zn, etc. which are bulk and the metal having low Young's modulus or by changing the temp. of the base plate. A high polymer base plate 2 is enumerated by polyolefin, polyamide, polyimide, etc. A lubricant coating layer 3 is obtd. by dissolving fatty acid, metallic soap, fatty acid amide, mineral oil, animal and vegetable oil, higher alcohol, silicone oil, fluorocarbon or the like in a solvent and coating the soln. on the base plate and drying the same or is obtd. by a dry process.

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 Magnetic recording media used for video recording, computer data recording, etc. have increased recording capacity.

It is well known that there is a strong desire to improve recording density in order to achieve downsizing of devices.

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. In view of the above circumstances, the currently proposed Co-N
A metal thin film type magnetic recording medium whose magnetic recording layer is a ferromagnetic metal thin film such as an i-○ based in-plane magnetized film or a Co-Cr based perpendicularly magnetized film has a shortest recording wavelength of 0.5 μm. Although it has been confirmed that it is possible to shorten the wavelength, and it is viewed as promising, it has the disadvantage that the ferromagnetic metal thin film cracks when used repeatedly, 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 magnetic recording layer to impart lubricity, thereby dispersing stress and suppressing the occurrence of cracks. Pretreatment of polymer substrates based on the idea that the adhesion strength is an important factor has been considered, but this is also insufficient.For example, when recording and reproducing using a rotating helical scan magnetic head, The running system has been devised to increase the amount of tension applied to the tape.

The reality is that even if the fluctuation is reduced, it is impossible to find a structure that can maintain the S/N ratio even after 100 cycles.

OBJECTS OF THE INVENTION An object of the present invention is to provide a metal thin film type magnetic recording medium that uses a ferromagnetic metal thin film as a magnetic recording layer and has a stable S/N ratio even after repeated use.

Structure of the Invention The metal thin film magnetic recording medium of the present invention has a magnetic recording layer made of a ferromagnetic metal thin film on a polymer substrate, and the Young's modulus of the ferromagnetic metal thin film is equal to the Young's modulus of the polymer substrate. It is characterized in that even if repeated recording and reproduction are performed, cracks do not occur, but even if cracks occur, a medium that can be used with almost no decrease in S/N can be obtained.

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, the ferromagnetic metal thin film 1 includes Co, Fe, Ni,
Co-Fe, Co-Ni, Co-B.

Co-Cu, Co-Ge, Co-Mn,
Co-Mg, Co-Mo.

Co-Pt, Co-Ru, Co-Rh, Co-
3i, Co-8m.

Co-Gd, Co-Ta, Co-V, Co-W
, Co-Y, Co-Zn.

Co-Cr, Co-Ti, Co-Ce, Co-N
i-Cr, Co-Ni-Mg, Co-Ni-I
n, Co-Cr-8n, etc., and partial oxide films and two-part nitride films thereof.

Methods for producing the thin film include electroless plating, ion beam deposition, and ion blating.

It can be appropriately selected from known thin film forming techniques such as sputtering and electron beam evaporation. The Young's modulus of the thin film can be adjusted, for example, by adjusting the material t.
1, In, which is a metal with a low Young's modulus in bulk,
Addition of Sn, Zn, etc. can be done by changing the temperature of the substrate.

Examples of the polymer substrate 2 include polyesters such as polyethylene terephthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose diacetate and nitrocellulose, polycarbonate, polyvinyl chloride, polyamide 1-pack polyimide, etc., and an undercoat layer. or a back coating layer, it shall be considered as the polymer substrate 2 including it. The lubricant coating layer 3 contains fatty acids, metal soap, fatty acid amide, and mineral oil.

Animal and vegetable oils, higher alcohols, silicone oils.

It is obtained by dissolving fluorocarbons etc. in a solvent and applying and drying it, or by a dry method.

In the present invention, by making the Young's modulus of the polymer substrate using the above-mentioned constituent materials and the ferromagnetic metal thin film the same value, cracks will occur in the ferromagnetic metal thin film during repeated use in a tape recorder.
It prevents the S/N reduction from occurring especially at short wavelengths, and it is sufficient even if the Young's modulus is set to such a large value, and even if cracks occur, there is almost no effect on the reduction in g/N. It's a quiet thing.

In the present invention, equivalent means that the difference in Young's modulus between the two is 50
Kg/ma range.

To that extent, it is thought that the above effects are produced even if the overall Young's modulus is not so large, probably because no large strain occurs at the interface between the polymer substrate and the ferromagnetic metal thin film.

Further, specific examples of the present invention will be described in detail.

[Example-1] Young's modulus 550 Kg/mn+, thickness 10.571
ferromagnetic metal thin films with different Young's modulus from diagonal vapor deposition on polyethylene terephthalate film of 0.131+m
30099m of mi+)stinic acid dissolved in methyl isobutyl ketone was applied on top of it so that the thickness after drying was approximately 60 mm, and a magnetic tape with a width of 8 mm was made.
．． Using a rotating helical scan method using a rotating cylinder with a diameter of 40 and equipped with a ferrite head with a gap length of 3 μm, the track width is 12 μm and the relative speed of the tape head is 3.5 μm. Recording and reproduction of a 5 MHz signal was repeated at a rate of 5 m/sec, and the change in S/N was compared using the first reproduction value of each tape as Of: dB).

However, the measurement environment was kept constant at 33° C. and 85% RH.

The degree of vacuum when forming the ferromagnetic metal thin film is 8X10'T.
orr oxygen partial pressure and other remaining gas partial pressures are 1.3
The configuration was maintained at 10 Torr.

The table shows the conditions for the ferromagnetic metal thin film, the S/N measurement results, and the results of surface cancer detection using an optical microscope at 300x magnification after the test.

As is clear from the table, except for tape 4, the playback level at the 400th pass also changed, and from the results of surface cancer detection on tape 2, S
It can be seen that there are no cracks that affect /N.

[Example-2] Young's modulus of 9 μm thick polyethylene terephthalate is 4
Using two types of substrates, osK9/- and 610 Kg/ml (/J), targets made of Co--Cr-8n were prepared with different component ratios, and a perpendicularly magnetized film of 0.18 .mu.m was formed by a high-frequency sputtering method. Formation of a coating layer of myristic acid thereon and slitting were carried out in the same manner as in Example-1, and the same evaluation as in Example-1 was performed. The results are shown in FIG.

Figure 2 shows the S/N of the 400th pass.
All tapes with N worse than -2 (dB) had strong cracks, but the products of the present invention had no cracks.

Effects of the Invention By disposing a ferromagnetic metal thin film with a Young's modulus equivalent to that of a polymer substrate as a magnetic recording layer, the present invention provides a magnetic recording layer that does not suffer from S/N deterioration due to cracks that occur during repeated use in a tape recorder. Its practical value as a recording medium is great.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the magnetic recording medium of the present invention, and FIG. 2 is a diagram showing the relationship between constituent elements and characteristics of the magnetic recording medium of the present invention. 1...Ferromagnetic metal thin film, 2...Polymer substrate. Name of agent: Patent attorney Toshio Nakao and one other person
11″!’I Fig. 2 Young f CKvmm”:J

Claims (1)

[Claims] Metal thin film magnetic recording comprising a magnetic recording layer made of a ferromagnetic metal thin film arranged on a polymer substrate, wherein the Young's modulus of the ferromagnetic metal thin film is equivalent to the Young's modulus of the polymer substrate. Medium.