JP2596072B2 - 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 Recent advances in recording technology have significantly improved not only the recording density per unit area but also the unit density, and magnetic recording media have a very smooth surface and magnetic recording of ferromagnetic metal thin films suitable for high density. Practical application of a vapor deposition tape or the like as a layer is strongly desired. Therefore, recently, the importance of research on tribology for deepening understanding of friction, wear, etc. occurring at the sliding interface has been recognized, and development has been promoted in various fields [Television Society of Japan Vol.40, No.6 (1986) 472]. page〕.

FIG. 2 is an enlarged sectional view of a conventional magnetic recording medium. In FIG. 2, reference numeral 1 denotes a polymer film such as polyethylene terephthalate, polyimide or the like, which is provided with a finely divided surface as required [Japanese Patent Application Laid-Open Nos. 59-207422 and 59-121631] Gazette] is used. Reference numeral 2 denotes a magnetic recording layer such as a Co—Ni—O obliquely deposited film, a perpendicular magnetization film such as Co—Cr or Co—Cr—Nb, 3 denotes a protective layer, 4 denotes a back coat layer, and carbon powder and calcium carbide. A resin layer containing particles such as powder is often provided when a protective layer alone is not sufficient to mainly improve running properties.

Conventionally, the protective layer has been improved in abrasion resistance by a deposited film of a fatty acid metal salt disclosed in JP-A-54-113303.
Examples of using a sputtered film of a polymer having an imide group and a diamond-like hard carbon film disclosed in Japanese Patent Application Laid-Open No. 57-11671 (Japan Society of Applied Magnetics, 46th meeting) are known. As a layer for lubricating purposes, there have been many attempts to coat a fatty acid, a fatty acid amide, or the like with a vapor deposition method, a wet coating method, or the like (for example, Japanese Patent Publication No. 56-30609). However, in the above-mentioned example, the improvement by the combination is being studied because it is not possible to cope with the expansion of the use environment conditions and the sophistication of the demand for practical use of the alloy-based magnetic head. (Japanese Patent Application Laid-Open No. 61-120331), a type in which a fluorine-containing lubricating oil layer is disposed on a hard carbon layer (Japanese Patent Application Laid-Open No.
No. 61-126627), and a lubrication layer formed on a Si-NO-based thin film (Japanese Patent Application Laid-Open No. 61-131231).

Problems to be Solved by the Invention However, camera-integrated video, which has been rapidly increasing in demand in recent years, has been reduced in size and weight, the range of use conditions has been widened, the overall thickness of magnetic tape has been reduced, and recording has been maintained for a long time. If this is attempted, there is a problem that the image quality is reduced by repeated recording and reproduction, and improvement has been desired.

The present invention has been made in view of the above circumstances, and provides a magnetic recording medium that can ensure image quality.

Means for Solving the Problems To solve the above-mentioned problems, the magnetic recording medium of the present invention has a protective film disposed on a non-magnetic thin film and a ferromagnetic metal thin film repeatedly laminated, and a non-magnetic thin film and The protective film is made of a thin film having a Knoop hardness of 2500 [Kg / mm ² ] or more.

The magnetic recording medium according to the present invention has a small local size of the magnetic recording layer by effectively hardening the magnetic recording layer even when the load at the time of high-speed sliding with the rotating magnetic head is increased due to the downsizing of the device. Destruction is hindered, and image quality can be secured even if recording and reproduction are repeatedly performed.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an enlarged sectional view of the magnetic recording medium of the present invention. In FIG. 1, reference numeral 5 denotes a polymer film of polyethylene terephthalate, polyether ketone, polyphenylene sulfide, polyimide or the like in the range of 5 μm to 10 μm, and an earthworm-like undercoat layer of a water-soluble polymer, TiO ₂ , C
A coating layer on which fine particles such as r ₃ O ₃ and polyester spheres are previously disposed may be used. 6 and 8 are nonmagnetic thin films and B
N _X, SiN _X, Knoop hardness 2500 diamond thin film or the like [Kg / m
m ² ) or more, 7, 9 are ferromagnetic metal thin films, Co, Co-F
e, Co-Ni, Co-O, Co-Ta, Co-Mo, Co-Cr, Co-Ni-O, Co-
Ni-Cr, Co-Cr-Nb, etc. are formed by electron beam evaporation, ion plating, sputtering, etc.
Five to five layers are preferred. 7 and 9 may be the same material,
Different materials and different directions of the axis of easy magnetization may be used. Reference numeral 10 denotes a protective film, but it is desirable to select a constituent material from the same group as 6, 8 and to form a protective film in the range of 50 to 200 mm in terms of spacing loss. 11 is a lubricant layer, fatty acid,
It can be appropriately selected from fatty acid amide, perfluoropolyether and the like. Reference numeral 12 denotes a so-called backcoat layer provided for the purpose of improving running properties, which is constituted by a known technique in a range of 0.3 μm to 0.7 μm, and desirably has a maximum roughness of 3000 mm or less.

Hereinafter, more specific examples will be described in comparison with comparative examples. 10 / (μm) ² Cr ₂ O ₃ fine particles with a diameter of 150 mm are arranged on a 7 μm-thick polyethylene naphthalate film, and any of reactive evaporation (RE), sputtering (SP), and plasma CVD (PCVD) is used. BN _X , SiN _X , TiN _X , BC _X
Or a diamond thin film, adjust Knoop hardness, arrange a non-magnetic thin film, and place a ferromagnetic metal thin film along a 1 m diameter cylindrical can at a minimum incident angle of 46 degrees and an oxygen partial pressure of 4 × 10
^{At -5} (Torr), Co-Ni (Co: 80wt%) was deposited by 700 ° electron beam evaporation. The protective film is composed in the same way as the non-magnetic thin film, and the lubricant layer is a back coat containing 45% of perfluoroarachidic acid by vacuum evaporation and a 1: 1 ratio of CaCO ₃ and carbon to 30% by weight of polyester fat. The layers were arranged in 0.4 μm to form an 8 mm wide magnetic tape. Each tape was converted to an 8 mm video, the cylinder diameter was reduced to 25 mm, the carrier frequency was set to 7 MHz, and the playback image quality was measured with an S / N meter and compared. By changing the environmental conditions, the number of repetitive playbacks and the initial relative S / N until the playback room decreased by 2 dB are summarized in the table and shown in comparison with the tape construction conditions.

The Knoop hardness of ferromagnetic metal thin films such as Co-Ni is 1000 [Kg / mm ² ] or less, including the results of investigations on non-magnetic thin films under different conditions for the first and second layers in addition to the above table. The required film thickness is about 500 to 3000 mm based on the amount of magnetic flux and the number of passes to reduce the S / N reduction to 2 dB or less is -25 ° C to + 50 ° C, 5% RH to 90%. In order to make it more than 60 times at% RH, the Knoop hardness of the non-magnetic thin film and the protective film is 25
It is desirable that the composition is not less than 00 [Kg / mm ² ]. 3
When the ferromagnetic metal thin film is multilayered into two to five layers, 2200 [Kg
/ mm ² ] can achieve the target, but even in that case 2500
Of course, if it is set to [Kg / mm ² ] or more, the deterioration of the image quality is further prevented.

Effects of the Invention As described above, according to the present invention, there is an excellent effect that a high-density magnetic recording medium with a small reduction in reproduced image quality even when used repeatedly is obtained.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a magnetic recording medium according to one embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a conventional magnetic recording medium. 5 ... Polymer film, 6,8 ... Non-magnetic thin film, 7,9 ... Ferromagnetic metal thin film, 10 ... Protective film.

Claims (1)

(57) [Claims] 1. A magnetic recording medium comprising a non-magnetic thin film and a ferromagnetic metal thin film repeatedly laminated and provided with a protective film, wherein the non-magnetic thin film and the protective film have a Knoop hardness of 2500 [Kg / mm ² ] or more. A magnetic recording medium characterized by the following.