JP2537915B2 - Magnetic recording media - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magnetic recording medium having a ferromagnetic metal thin film as a magnetic recording layer, which is suitable for high density magnetic recording and reproduction.

2. Description of the Related Art A coating type magnetic layer, which has been widely used as a magnetic recording layer in the past, has become difficult to secure a sufficient C / N in magnetic recording whose wavelength is becoming shorter and shorter in the future. Co-Cr, Co-Ni-O and other ferromagnetic metal thin film,
Practical application of magnetic recording media for magnetic recording layers is expected [IEEE TRANSACTIONS ON MAGNETICS] V
ol.MAG-21, No. 3, 1217-1220 (1985)]. In order to put the magnetic recording medium having such a structure into practical use, it is essential to secure durability in high-speed sliding contact with the magnetic head, and proposals for improvement from that point are increasing [for example, JP-A-53-53]. 88704
No. 59-121631, No. 59-171026, No. 59-171026
62-197917, etc.]. Among them, the method of forming fine irregularities on the magnetic recording layer is attracting a great deal of attention because of the effect of improving the durability of the magnetic recording layer [IEEE TRANSACTIO
NS ON MAGNETICS) Vol.MAG-21, No.5 1524 to 1526 (19
85)].

Problems to be Solved by the Invention However, on the polymer film, Al ₂ O ₃ , SiO ₂ , Ca
Magnetic recording media with a protective lubrication layer on which a ferromagnetic metal thin film is deposited by electron beam evaporation, sputtering, etc., on which a fine particle coating layer is coated and fixed with fine particles such as O and polyethylene spheres Is 0.5 μm or less, the C / N is insufficient, and improvement is desired.

The present invention has been made in view of the above-mentioned circumstances.
A magnetic recording medium having a good C / N is provided.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording medium of the present invention comprises a ferromagnetic polymer thin film on a smooth polymer film, and further comprises a hard carbon film and a lubricant. It is arranged.

Effect The magnetic recording medium of the present invention, which has the above-described structure, ensures microscopic uniformity of the ferromagnetic metal thin film, so that noise does not suddenly increase even when the recording wavelength is 0.5 μm or less. The C / N at a short wavelength can be ensured, and the required durability can be enhanced by the hard carbon film formed in a net shape so that the mutual auxiliary relationship with the lubricant can be strengthened.

Embodiments Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged sectional view of a magnetic recording medium according to one embodiment of the present invention. In the figure, 1 is polyethylene terephthalate,
A polymer film made of polyphenene sulfide, polyimide, polyether sulfone, etc., with a surface smoothness of 10Å to 50Å with an average roughness and 100Å even with a maximum roughness.
Up to smoothness is preferred. 2 is Co-Ni, Co-Cr, Co-Ta, C
It is a ferromagnetic metal thin film such as o-Mo, Co-W, Co-O, Co-Ni-O, Co-Cr-Nb, etc., which is not related to the direction of the easy axis of magnetization, and the manufacturing method is electron beam evaporation method. The sputtering method is not particularly limited. If necessary, it may be formed through an underlayer of titanium, germanium, chromium or the like, or a soft magnetic layer of permalloy or the like. 3 is a net-like hard carbon thin film with a maximum height of at most 150Å, preferably 100Å to 60Å
It shall consist of up to. Reference numeral 4 is a lubricant such as fatty acid, fatty acid ester, perfluoroalkylcarboxylic acid, perfluoroalkylsulfonic acid. A simple method of obtaining such a constitution is to first vaporize the lubricant of 4 in an island shape, and then form a carbon thin film by sputtering graphite and discharge decomposition of a hydrocarbon-based gas to evaporate the lubricant. By doing so, the hard carbon thin film is not formed in that portion, and as a result, the mechanism that the hard carbon thin film is formed like a net is utilized. Hereinafter, one example of the present invention will be described more specifically in comparison with a comparative example. Thickness of 12μm, average surface roughness of 20Å, maximum of 55Å polyethylene terephthalate surface 16kev, 1
Electron beam irradiation pretreatment of 6μA / cm ² was performed, and Co-Cr (Cr20.5wt%) perpendicular magnetization film was formed on it 0.12μm by high frequency sputtering method, and myristic acid was formed on it by vacuum evaporation method. Is deposited in an island shape and becomes a uniform film with a thickness of 20Å (the total area ratio of islands is 33%), and graphite is used as a target for Ar + H ₂ = 3 × 10 ^-3 (Torr), Ar:
Sputtering was performed by glow discharge of 13.56 (MHz) 1.2 (KW) with H ₂ = 1: 3 to form a diamond-like hard carbon film in a net shape. The film thickness was 70Å, and perfluoromyristic acid was vacuum-deposited with a uniform film thickness of 40Å to obtain a magnetic tape of 8 mm width. The comparative example uses the same polyethylene terephthalate film as the example with a thickness of 12μ, and a diameter of 100
Å CaCO ₃ of 10 pieces / (μm) ^{2 are} arranged and Co-Cr
A perpendicular magnetized film (Cr: 20.5 wt%) was formed to a thickness of 0.12 μm, a diamond-like hard carbon film was formed to 200 Å, and perfluoromyristic acid was vapor-deposited to about 50 Å to manufacture an 8-mm wide magnetic tape. Both tapes were evaluated by the modified 8 mm video. With a composite type ring head of sendust sputtered film with a gap length of 0.16 μm and a ferrite, a rectangular wave with a bit length of 0.26 μm and a track width of 7 μm was recorded, and a band 8
The C / N at (MHz) was compared. The example is 5.5 (d
B) Good C / N is shown, and the still characteristics output is 2 from the initial level.
The time until it decreases (dB) is the same level as 85 (minutes) in the example and 87 (minutes) in the comparative example, and this durability has a net-like hard carbon film equivalent to a continuous film. In addition, the difference in actual spacing loss is large because the hard carbon thin film may be thin, and C / N
Contributes to the difference.

EFFECTS OF THE INVENTION As described above, according to the present invention, there is an excellent effect that a magnetic recording medium having an excellent C / N at a short wavelength can be obtained.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention. 1 ... Polymer film, 2 ... Ferromagnetic metal thin film, 3 ...
Reticulated hard carbon thin film, 4 ... Lubricant.

Claims (1)

(57) [Claims] 1. A magnetic recording medium characterized in that a ferromagnetic metal thin film is provided on a smooth polymer film, and a hard net carbon film and a lubricant are provided thereon.