JPH083896B2 - Magnetic recording media - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium using a ferromagnetic metal thin film as a magnetic recording layer in a magnetic tape or a magnetic disk used for increasing the density of magnetic recording. .

2. Description of the Related Art Due to recent advances in recording technology, the amount of recorded information per unit area has dramatically increased, and ferromagnetic metal thin films such as Co-Ni, Co-Cr, and Co-Ni-O are used as magnetic recording layers. Practical application of magnetic recording media has been strongly desired. In order to put such a magnetic recording medium into practical use, it is important to deepen the understanding of tribology and realize a reliable lubricating system [Journal of the Television Society of Japan, vol.40, NO-6,472 (1986)].

FIG. 2 is an enlarged sectional view of a conventional magnetic recording medium.
In the figure, 1 is a non-magnetic substrate such as a polyester film or an Al alloy, and an undercoating layer for shape imparting is used if necessary. 2 is Co-Ni, Co-Ni-O, Co-Ni. −Pr−O, C
A ferromagnetic metal thin film type magnetic recording layer 3 formed by an electron beam evaporation method such as o-Cr or Co-O or a sputtering method is a protective film. In the medium shown in FIG. 2, the examination of the protective film is the center of tribology, and many materials and manufacturing methods have been proposed in which the spacing loss is minimized and the protective effect is maintained.

Vapor deposition film of fatty acid metal salt (JP-A-54-113303) Sputtered film of polymer having imide group (JP-A-57-116771)
No.), a coating film of fatty acid amide (Japanese Patent Publication No. 56-30609),
A combination of a fluorocarbon-based lubricating layer on a fatty acid metal salt adsorption layer (Japanese Patent Laid-Open No. 61-120331), a diamond-like hard carbon film [Japan Applied Magnetics Society, 46th Research Meeting Material (1986)], carbon Membrane [IEEE Transactions on Magnetics (IEEE TRANSACTION
SON MAGNETICS) vol.MAG-22, NO-5, PP999 ~ 1001 (19
86)], and a fluorine-containing lubricating oil layer disposed on a hard carbon layer (JP-A-61-126627), and the like.

Problems to be Solved by the Invention However, in the above-described configuration, the durability is insufficient in an environment with low humidity, and therefore improvement has been desired.

The present invention has been made in view of the above circumstances, and provides a magnetic recording medium capable of ensuring practicability in an environment with low humidity even when the thickness of the protective layer is reduced.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording medium of the present invention has a diamond-like hard carbon film (DLC film) arranged on a ferromagnetic metal thin film, and the DLC film contains metal ions. In addition to the injection layer, a lubricant layer containing either carboxylic acid or fatty acid or sulfonic acid is provided.

Action The magnetic recording medium of the present invention has the above-mentioned constitution, and the lubricant strongly reacts with the DLC film to remarkably improve the protection property, so that even if a part of the DLC film is lost, the tape is not damaged. Even if the DLC film is thinned to improve spacing loss, durability will be ensured.

Example Hereinafter, a magnetic recording medium according to an example of the present invention will be described in detail 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 FIG. 1, 4 is polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polysulfide,
If necessary, a polymer film of polyamideimide, polyimide or the like having an undercoat layer in which inorganic fine particles, organic fine particles or the like are dispersed and applied can be used. 5 is Co, C
o-Ag, Co-Cr, Co-Ge, Co-Hf, Co-Mo, Co-Nb, Co-Os, Co
-O, Co-P, Co-Ru, Co-Si, Co-Sm, Co-Ta, Co-Ti, Co-
V, Co-W, Co-Zr, Co-Ni, Co-Ni-O, Co-Cr-Nb, Co-Ni
A ferromagnetic metal thin film such as -Pr, Co-Ni-Pr-O, 6 is a diamond-like hard carbon film, and in consideration of spacing loss, it is preferably 150 Å or less and about 50 Å or less. Reference numeral 7 denotes a metal ion implantation layer, which may be appropriately selected from alkali metals, alkaline earth metals and the like. The injection amount can be optimized in the range of ² μA / cm ² to 100 μA / cm ² , and the ions used are 10 KeV to 5
The range of 0 KeV is preferred. 8 is a lubricant containing at least one of fatty acid, carboxylic acid and sulfonic acid, and the total amount of lubricant is in the range of 0.1 μg / cm ² to 2 μg / cm ² , and the range of 25% to 69% is It is preferable to occupy one of the above lubricants.

The embodiment of the present invention may be any of a magnetic tape, a magnetic disk, and a magnetic card. Hereinafter, more specifically, one example of the embodiment will be described in comparison with a comparative example.

On a polyethylene terephthalate film with a thickness of 11 μm, earthworm-shaped protrusions with a height of 70 Å of butadiene rubber are arranged, and Co-Cr-Nb (Co-
≈80.5 Cr = 13 Nb = 6.5 wt%) Sputter-deposited film by 0.12 μm under the condition that perpendicular magnetization is possible, and using graphite as a target, Ar + H ₂ = 0.07 Torr Ar / H ₂ = 1/2 gas A DLC film of 70 Å was formed by a sputtering method with a high-frequency glow discharge of 13.56 MHz 1.2 KW, and Na ⁺ ions were injected at 22 μA / cm ² , 17 KeV on it, and 55% stearic acid and A lubricant containing 45% of acid amide was vacuum-deposited at 0.5 μg / cm ^{2 in} Example A, and perfluorocapric acid (carboxylic acid) was used as a lubricant at 0.35 μg / cm ^2.
Two solutions were applied to Example B, and a mixture of 25% paratoluenesulfonic acid 25%, adipic acid 45% and butyl stearate 30% as a lubricant was 0.4 μg / cm ² vacuum deposited, and Example C was used. Each was cut into a width of 8 mm to obtain a magnetic tape. On the other hand, as a comparative example, without implanting Na ⁺ ions, the other conditions were the same, and an 8 mm wide magnetic tape, comparative examples A, B and C were used.
Were manufactured respectively.

A commercially available 8 mm video [VX-801, manufactured by Matsushita Electric Industrial Co., Ltd.] was modified from these tapes, and recording / reproduction was performed at a wavelength of 0.35 μm by a sendust head having a gap length of 0.14 μm.

During still reproduction at 20 ° C. and 60% RH, the time until the reproduction output decreased by 2.4 dB was 92 to 95 minutes in Example A, and 87 to in Example B.
90 minutes, Example C was 97 to 101 minutes, Comparative Example A was 21 to 49 minutes, Comparative Example B was 15 to 31 minutes, and Comparative Example C was 16 to 29 minutes.

In still reproduction at 5 ° C. and 5% RH, the time required for the reproduction output to decrease by 3 dB is 90 to 93 minutes in Example A and 116 in Example B.
~ 118 minutes, compared to 87-90 minutes in Example C,
Comparative Example A was 9 to 27 minutes, Comparative Example B was 15 to 29 minutes, and Comparative Example C was 6 to 20 minutes, which was short and had large variations.

When the reproduction was repeatedly performed under the above-mentioned two kinds of environments, in each of the examples, A, B, and C showed almost no change within 1 dB.
Comparative example is 20 ~ 60% RH, comparative example A is 2.2 ~ 3dB, comparative example B
Is 2.4 to 3.3 dB, Comparative Example C is 2.5 to 3.6 dBS / N, and
S / N was 3.5 to 5.2 dB in Comparative Example A at 5% RH, Comparative Example B
Was 3.3 to 4.9 dB, and Comparative Example C was 3.7 to 6.4 dB.

EFFECTS OF THE INVENTION As described above, according to the present invention, there is an excellent effect that a high output magnetic recording medium having sufficient durability can be obtained even in an environment having a particularly low humidity regardless of the use environment.

[Brief description 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. 4 ... Polymer film, 5 ... Ferromagnetic metal thin film, 6 ...
DLC film, 7 ... Ion implantation layer, 8 ... Lubricant layer.

Claims (1)

[Claims] 1. A diamond-like hard carbon film is disposed on a ferromagnetic metal thin film layer, a metal ion-implanted layer is disposed on the carbon film, and a lubricant layer containing a carboxylic acid, or a fatty acid or a sulfonic acid. A magnetic recording medium characterized by being provided with.