JP2512005B2 - Magnetic recording media - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording medium using a ferromagnetic metal thin film suitable for high-density magnetic recording as a magnetic recording layer.

2. Description of the Related Art In recent years, the magnetic recording medium has a limit in its frequency characteristics improvement due to high coercive force and surface smoothing in relation to the magnetic head. Therefore, a magnetic recording medium using a ferromagnetic metal thin film as a magnetic recording layer has been found. There is a strong demand for the practical use of (Japanese Patent Publication No. 56-23
No. 208, Japanese Patent Publication No. 58-91, JP-A No. 61-77128, etc.). Practical application of such a magnetic recording medium depends on whether or not durability can be imparted to an extremely thin ferromagnetic metal thin film of about 0.1 μm while securing a desired signal-to-noise ratio (hereinafter referred to as C / N). It is no exaggeration to say that Therefore, some improvement approaches have been taken, and a method of forming a high-density projection shape on the magnetic recording layer itself (JP-A-59-84927,
59-121631, 58-10021, 60-21962, 61
-74139, 61-16019, 60-9363, etc.) or a combination of an overcoat and a lubricant that has been studied for a long time, and a combination of an amorphous carbon film and a fluorocarbon lubricant. (JP-A-61-14
2525), a combination of an amorphous Si-N-O film and a fluorocarbon-based lubricant (JP-A-61-131231), hard carbon and a fluorine-containing oil (JP-A-61-1266).
No. 27), and many other proposals have been made.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-mentioned configuration, even if the fine particle structure and the overcoat layer are combined, if an attempt is made to obtain sufficient durability, an effective total of the overcoat film thickness and the lubricant is obtained. The amount that affects the spacing loss of thickness is 200
Since about Å is required, future magnetic recording with a shorter wavelength will sacrifice the short wavelength output, and therefore improvement has been desired.

The present invention has been made in view of the above circumstances, and provides a durable magnetic recording medium with a small spacing loss.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording medium of the present invention has a ferromagnetic metal thin film A on a polymer film, and a strong magnetic film containing fine particles having exposed tips. The magnetic metal thin film B is arranged, and the hard carbon thin film having a height lower than the height of the fine particles exposed on the thin film B is arranged.

The magnetic recording medium of the present invention having the above-mentioned structure directly and mainly slides on the magnetic head constituent material at high speed due to the exposed fine particles, and the contact with the smooth part occurs suddenly. However, since that portion is protected by the hard carbon film, the magnetic recording layer is less likely to be destroyed, and the exposed height of the tip can be reduced, so that the spacing loss can be reduced.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged cross-sectional view of a magnetic recording medium according to an embodiment of the present invention, in which 1 is a polymer film such as polyphenyl sulfide, polyether sulfone, polyethylene naphthalator and polyamide imide, and 2 is a ferromagnetic metal. In the thin film A, Co, Co-Ni, Co-Fe, Co-Cu, Co-Cr, Co-O, Co
-Cr-Nb, Co-Ni-O, Co-Ni-Pr-O, etc. are formed by a thin film forming method such as electron beam evaporation method or high frequency sputtering method. The film thickness is up to 2000 Å, if necessary. It is also possible to have a multilayer structure. 3 is a fine particle, CaCO ₃ , Si
Inorganic fine particles such as O ₂ , Eu ₂ O ₃ , Cr ₂ O ₃ , MoS ₂ , WS _{2 and the} like, 4 is a ferromagnetic metal thin film B, and the material and manufacturing method can be appropriately selected from the same group as 2. However, it is needless to say that the film pressure of 4 is smaller than the diameter of the fine particles 3 and the thickness of the hard carbon thin film of 5 is also set to be smaller than the diameter of the fine particles. Although it depends on the density of the particles, a difference of about 50Å is required. To obtain a structure in which the tips of the fine particles are exposed from the thin film, the fine particles are arranged on the thin film as usual, and then the thin film is removed by polishing, or the low boiling point material is attached to the projection tips by the transfer method. At the very least, it can be carried out by any method of preventing the low boiling point material from evaporating at the time of forming the thin film and forming the thin film on that portion. The method for forming the hard carbon thin film may be appropriately selected from a method using plasma of hydrocarbon gas, a method of forming a target with graphite and a sputtering method, and the like. Reference numeral 6 is a lubricant layer of perfluorocarboxylic acid, perfluoroalkylsulfonic acid, perfluoropolyether or the like, which is formed by a solution coating method, a vacuum deposition method or the like. Hereinafter, one example of the present invention will be described more specifically in comparison with a comparative example.

Prepare a polyethylene terephthalate film (surface roughness, 20Å) with a thickness of 12 μm, blow discharge the surface [13.56 (MHz), 2 (KW), 0.01 (Torr) oxygen], and place it on a cylindrical can with a diameter of 1 m. Along with the film, while winding the film, in a oxygen of 5.2 × 10 ^-5 (Torr), Co-Ni (C
o: 80wt%) and electron beam evaporation at a minimum incident angle of 45 degrees
A Å Co-Ni-O film is formed, and MoS ₂ particles having a diameter of 600 Å adsorbed with water are placed on the surface of 3 × 10 ⁷ pieces / cm ² and the same vapor deposition machine is used to deposit 3.8 × 10 ^-5. (Torr) oxygen in Co-Ni (Co: 80
wt%) with electron beam evaporation at a minimum incident angle of 55 degrees,
An o-Ni-O film was formed. At that time, set the cylinder can temperature to 60.
At a temperature of ℃, the adsorbed moisture from MoS ₂ was heated and vaporized during the vapor deposition so that the Co—Ni—O film was not formed in the MoS ₂ fine particle portion. Furthermore, using graphite as a target, Ar
And then a mixed gas of H ₂ to the discharge gas 2 × 10 ^-2 (Torr) [A
r: H ₂ = 1: 3], 2.5 (KW) 13.56 (MHz) was used to form 50 Å diamond-like hard carbon thin film by sputtering. Before forming this thin film, palmitic acid was transferred to the tips of the projections by a roller, and operation was performed so that the thin film did not deposit during sputtering. In this state, 50 Å of perfluorooctanoic acid was formed by a vacuum vapor deposition method to obtain an 8 mm wide magnetic tape.

On the other hand, as a comparative example, the diameter of 30
0.5 Å SiO ₂ fine particles are arranged at 1.5 × 10 ⁹ pieces / cm ² and 1000 Å and 480 Å of Co-Ni-O films are vapor-deposited under the same conditions as in the example, and 150 Å diamond-like hard carbon thin film Was placed as Comparative Tape A, the one without this film was designated as Comparative Tape B, and perfluorooctanoic acid was added to 50Å
It was vacuum-deposited and processed to have a width of 8 mm.

By the 8mm video deck which remodeled each tape,
C / N was compared by raising the carrier frequency from 5 (MHz) to 7 (MHz) using a composite ring head with ferrite in which an amorphous alloy with a gap length of 0.2 μm was formed near the gap by sputtering. When comparing the initial values, set the comparison ratio B to O
(DB), the example is -0.7 (dB), and the comparative example A is-.
It was 2.3 (dB). In a comparison of repeated recording and reproduction in an environment of 40 ° C and 85% RH, the relative C / N with the initial value is 1 respectively.
At the 50th recording / reproduction, the example is -0.2 to -0.4 (dB), the comparative example A is -0.2 to -0.5 (dB), and the comparative example B is -2.3 to -3.8.
It was (dB). When the recording and reproducing are repeated 200 times at -5 ° C, the example is -0.5 to -0.9 (dB), and the comparative example A is -1.
1 to -1.5 (dB), Comparative Example B was -3.1 to -5.7 (dB).

EFFECTS OF THE INVENTION As described above, according to the present invention, there is an excellent effect that a magnetic recording medium having an improved balance of C / N and durability in a short wavelength region 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 A, 3 ...
... fine particles, 4 ... ferromagnetic metal thin film B, 5 ... hard carbon thin film.

Claims (1)

(57) [Claims] 1. A ferromagnetic metal thin film A is arranged on a polymer film, a ferromagnetic metal thin film B containing fine particles having exposed tips is arranged thereon, and fine particles exposed on the ferromagnetic metal thin film B. A magnetic recording medium comprising a hard carbon thin film having a height lower than the height.