JPS6334719A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain satisfactory C/N and good corrosion resistance in laminated constitution of partially oxidized thin ferromagnetic metallic films by having a magnetic recording layer disposed with a high-polymer separating layer without having an oxide layer at the lamination boundary face. CONSTITUTION:This recording medium is formed by disposing the high-polymer separating layer 9 to the laminated constitution of the partially oxidized thin ferromagnetic metallic films without having the oxide at the lamination boundary face. The magnetical sepn. between the respective laminated films is, therefore, good and since there is no oxide layer of the intermediate nonmagnetic layer viewed from the magnetic head, the spacing of the thin films on the side further from the magnetic head is smaller. The output is thereby increased and noise is decreased; therefore, the C/N is improved and since the electrochemical corrosion is negligible in spite of the adoption of the laminated constitution, the partially oxidized thin ferromagnetic metallic films are eventually constituted in the hardly corrosible state and the corrosion resistance is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording medium whose magnetic recording layer is a ferromagnetic metal thin film suitable for high-density magnetic recording.

Conventional technology The so-called vapor deposition tape, in which Co-Ni is obliquely vapor-deposited by electron beam evaporation directly or through an underlayer on a polymer film, can be preserved by introducing oxygen gas during vapor deposition and optimizing partial oxidation. Not only does it control magnetic force, but it also improves durability and corrosion resistance, making it more practical.
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Furthermore, attempts have been made to stack layers in order to improve corrosion resistance and reduce noise by making particles finer. FIG. 2 is an enlarged cross-sectional view of an example of a conventional magnetic recording medium. In FIG. 2, 1 is a polymer film such as a polyethylene terephthalate film, and 2.4 is a Cr vapor deposition layer formed by electron beam evaporation.
The thickness is 0.05 μm, 3 and 6 are Co-Cr obliquely deposited films, which contain 19 wt% of Cr, and have a coercive force of 1000.
(◯e) and u6, each having a thickness of 0.07 μm, is a protective film having a laminated structure of a plasma polymerized film of perfluorocyclobutane of 150 layers and a vapor-deposited film of Co salt of myristic acid of 40 layers.

Lamination with non-magnetic layers tends to improve noise, but
Corrosion may progress electrochemically, and there are limitations to the materials used.

Problems to be Solved by the Invention However, with the above configuration, as the recording wavelength becomes shorter, it becomes difficult to obtain a sufficient signal output to noise ratio (hereinafter referred to as C/N), so improvements are desired. Ta. The present invention was made in view of the above-mentioned circumstances, and provides a magnetic recording medium with sufficient C/N and good corrosion resistance.

Means for Solving the Problems In order to solve the above problems, the magnetic recording medium of the present invention comprises:
It has a laminated structure of partially oxidized ferromagnetic metal thin films, but has no oxidized layer at the laminated interface, but a polymer separation layer.

Function: The magnetic recording medium of the present invention has the above-described structure, and the magnetic separation between the laminated thin films is good, and when viewed from the magnetic head, there is no oxidized layer in the intermediate nonmagnetic layer.
Since the spacing of the thin film on the side far from the magnetic head is smaller, the output is larger and the noise is lower.
Since the C/N ratio is improved and electrochemical corrosion can be ignored even in a laminated structure, the partially oxidized ferromagnetic metal thin film is constructed in a state where it is difficult to corrode, and its corrosion resistance is also improved.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention. ,, 7 is a polymer film such as a polyethylene terephthalate film with a thickness of 10 and 4 μm, and 8 is a polymer film such as a cylindrical can with a diameter of 1 m, with a minimum incidence angle of 3
Co in oxygen at 2x 10-' (Torr) at 6 degrees
○, 066 μm electron beam evaporation, followed by sputter etching with Ar ions to remove the upper surface oxide layer, is the first magnetic thin film, 9 is from a polyester resin layer with a thickness of 40 μm containing silica fine particles to a diameter of 100 μm. 1° is the minimum incidence angle of 4 with the same device as the first magnetic layer.
The second magnetic layer was obtained by electron beam evaporation of Co 8 O-Ni 20 to a thickness of 0.07 μm in oxygen at 7° C. and 1×10 −′ (Torr). The interface between the second magnetic layer and the magnetic layer 9 can be freed from an oxidized layer by a small amount of gas degassing from the magnetic layer 9.

Reference numeral 11 denotes a lubricant layer made of perfluorostearic acid and having a thickness of approximately 40 μm formed by vacuum deposition.

As a comparative example, a 40-layer polyester resin layer containing 150-layer diameter silica fine particles was placed on a polyethylene terephthalate film with a thickness of 1.0 mm and 4 μm, and the above-mentioned second magnetic layer was laminated in two layers on top of the layer. Comparative Example A was prepared in which 40 layers of perfluorostearic acid were placed between the magnetic layers, and Comparative Example B was prepared in which chromium was deposited by electron beam evaporation to a thickness of 400 layers between the magnetic layers.

Using Example and Comparative Examples A and B, gap length 0.14 μm
With the sendust head, the relative speed is 3,4mlse
c. When recording frequency 6@, we compared the noise C/N at 6 rivers. If the example is 0 (dB), comparative examples A and B are -2, 1 (dB) and -3, 9 (dB), respectively.
Met. Place each tape in an environment of 60°C and 85SRH.
The C/N after being left for a week remained unchanged in Examples and Comparative Example A, whereas Comparative Example B decreased by 2 edB from the initial value.

In the example, a polyethylene terephthalate film was used as the polymer film, but other materials such as polyimide, polyphenylene sulfide, polyamideimide, polyethylene naphthalate, polycarbonate, etc. may be used, and a fine particle coating layer may be provided as necessary.

The magnetic layer is also made of Co-Fe-0 and Co-Cr-0.

Co-Ti-0, Co-W'-(J, Co-NLo-0
, Co-Pt-0.

Co-Ni-Pr-0, Co-NL-B-0 and the like may be used alone or in combination.

The polymer separation layer may be made of other resins such as epoxy resins, polyurethane resins, and many electron beam cured resins, and the fine particles may also be made of Al 203. CaOO3゜B
a S O4, Ca O, TiO2, Fe 304
etc. is fine.

Even if it does not contain fine particles, magnetic separation and corrosion resistance can be sufficiently improved, so it may be selected as appropriate.

The resin layer thickness is 208 to 20 mm, preferably 30 mm to 300 mm.
100 people would be appropriate.

Effects of the Invention As described above, according to the present invention, the C/N of the tape is good when short wavelength recording is performed, the corrosion resistance is good, and the C/N remains unchanged even when stored in a high humidity environment. This has an excellent effect in that a magnetic recording medium without deterioration can be obtained.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a conventional magnetic recording medium. 7... Polymer film, 8... First magnetic layer, 9... Polymer separation layer, 10... Second magnetic layer. Name of agent: Patent attorney Toshio Nakao and 1 other person7-
-~17i minutes) Fill/; Figure 2

Claims (1)

[Claims] 1. A magnetic recording medium having a laminated structure of partially oxidized ferromagnetic metal thin films, and having a magnetic recording layer having a polymer separation layer without an oxidized layer at the laminated interface.