JPH0227517A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent the degradation of the image quality in repetitive recording and reproducing by forming thin nonmagnetic films and protective film of thin films having specific hardness. CONSTITUTION:After the thin nonmagnetic films 6, 8 and thin ferromagnetic metallic films 7, 9 are repeatedly laminated, the protective film 10 is disposed thereon. The thin nonmagnetic films 6, 8 and the protective film 10 are constituted of the thin films having >=2,500kg/mm<2> Knoop hardness. The magnetic recording layer is, therefore, effectively hardened. Even if the load at the time of high-speed sliding with a rotary magnetic head is increased by the miniaturization of the apparatus, the local destruction of the magnetic recording layer is prevented. The high-density magnetic recording medium with which the reproducing image quality in repetitive use is less degraded is obtd. in this way.

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 Recent advances in recording technology have significantly improved recording density not only per unit area but also per unit volume, and magnetic recording media are made of ferromagnetic metals with extremely smooth surfaces and suitable for high density There is a strong desire to put into practical use a vapor-deposited tape or the like that uses a thin film as a magnetic recording layer. Therefore, the importance of research on tribology to deepen understanding of friction, wear, etc. that occurs at sliding interfaces has recently been recognized, and development is progressing in various fields [Television, 7 Journals Vol. 1.40.46 (1986) 47
2 pages].

FIG. 2 is an enlarged sectional view of a conventional magnetic recording medium. Second
In the figure, 1 is a polymer film made of polyethylene terephthalate, polyimide, etc., which is provided with a finely divided surface if necessary [JP-A-59-207422, JP-A-59-121631] Publication is used. 2
Co-Ni-0 obliquely deposited film, Co-Cr, Go-Or
- A magnetic recording layer such as a perpendicular magnetization film such as Nb, 3 is a protective layer, and 4 is a back coat layer, which is a resin layer containing particles such as carbon powder and calcium carbide powder, mainly to improve the run. It is often provided when a protective layer alone is insufficient.

Conventionally, the protective layer has been improved in wear resistance by a vapor-deposited film of a fatty acid metal salt disclosed in JP-A-54-113303;
Known examples include the sputtered film of a polymer having imide groups disclosed in JP-A-57-116771, and an example using a diamond-like hard carbon film (Japan Society of Applied Magnetics, 46th Research Meeting Materials). . Also, as a layer for lubricating purposes, vapor deposition method.

Many attempts have been made to coat fatty acids, fatty acid amides, etc. by wet coating methods (for example, Japanese Patent Publication No. 30609/1983). However, in the above-mentioned example, it is impossible to cope with the expansion of usage environmental conditions and the increasing sophistication of practical requirements for two-alloy magnetic heads. Therefore, improvements by combination are being considered, and fluorocarbon system with a lubricating layer (Japanese Unexamined Patent Publication No. 1986-12)
No. 0331), and a fluorine-containing lubricating oil layer arranged on a hard carbon layer (Japanese Patent Application Laid-open No. 126627/1983).
, noodles with a lubricating layer formed on a 5i-N-0 thin film (Japanese Unexamined Patent Publication No. 131231/1983).

Problems to be solved by the invention However, the demand for camera-integrated video cameras, which has been rapidly increasing in recent years, has become smaller and lighter, and the range of usage conditions has become wider. However, when attempting to do so, there was a problem in that the image quality deteriorated during repeated recording and playback, and improvements were desired.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a magnetic recording medium that can ensure image quality.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording medium of the present invention comprises:
A product in which a protective film is arranged on a repeatedly laminated layer of a nonmagnetic thin film and a ferromagnetic metal thin film, and the nonmagnetic thin film and the protective film are made of a thin film with a Knoop hardness of 2500 (Ky/-) or more. It is.

Function The magnetic recording medium of the present invention effectively hardens the magnetic recording layer even when the load increases during high-speed sliding with a rotating magnetic head due to the miniaturization of equipment. Local destruction can be prevented, and image quality can be maintained even when repeating recording and reproducing is performed.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is an enlarged sectional view of the magnetic recording medium of the present invention. In Figure 1, 5 is polyethylene terephthalate with a diameter ranging from 6 μm to 10 μm.

A polymer film made of polyetherketone, polyphenylene sulfide, polyimide, etc., on which a worm-shaped undercoat layer of water-soluble polymer and a coating layer containing fine particles such as TtO2, Cr2O3° polyester spheres, etc. are arranged in advance. Good too. 6 and 8 are non-magnetic thin films and are BN! , S i
N, , Knoop hardness 2soo [:
Kg/-) or more, 7 and 9 are ferromagnetic metal thin films,
Go, Co-Fe, Co-Ni.

Co-0, Co-Ta, Co-Mo, Co-0r, Co
Electron beam evaporation method using -Ni-0°Co-Ni-Cr, Co-Cr-Nb, etc.

It is formed by an ion blasting method, a sputtering method, etc., and the number of layers is preferably 2 to 6 layers. A and 9 may be made of the same material, or may be made of different materials and have different directions of easy magnetization axes. 10 is a protective film, but the constituent material was selected from the same group as 6 and 8, and 60 was selected from the viewpoint of spacing loss.
It is desirable that the number range from 1 to 200 people. Reference numeral 11 denotes a lubricant layer, which can be appropriately selected from fatty acids, fatty acid amides, perfluoropolyethers, and the like. Reference numeral 12 denotes a so-called back coat layer provided for the purpose of improving runnability, and is formed using a known technique to have a thickness in the range of 0.3 μm to 0.7 μm, and preferably has a maximum roughness of 3000 Å or less.

Hereinafter, more specific examples will be explained in comparison with comparative examples. Cτ203 fine particles with a diameter of 150 were placed 10 pieces/(μ
m) 2 layers, reactive vapor deposition (RE).

Sputtering method (SP)? Plasma CvD method (PC
VD), BN, SiNx, TiN,.

BC! etc., a diamond thin film, etc., adjusted the Knoop hardness, arranged a non-magnetic thin film, and placed the ferromagnetic metal thin film along a cylindrical can with a diameter of 1 m, with a minimum incident angle of 46 degrees and an oxygen partial pressure of 4 x 10"- 5 (Torr), Co-Ni (
Co: 80wt%) was deposited by 700 electron beam evaporation. The protective film was constructed in the same manner as the non-magnetic thin film, and the lubricant layer was made of 46 layers of perfluoroarachidic acid by vacuum evaporation, and a backing containing 30% by weight of CaCO3 and carbon in a ratio of 1:1 to the polyester resin. The coating layer is 0.
The magnetic tape was 8mm wide with a 4μ distribution. Each tape was modified to 8mm video, the cylinder diameter was reduced to 26 states, the carrier frequency was changed to 7 MHz, and the playback quality was increased to S/N.
Measured with a meter and compared. The number of times of repeated playback until the playback image quality deteriorates by 2 dB and the initial relative S/N are summarized in a table and compared with the tape configuration conditions while changing the environmental conditions.

In addition to the above table, the Knoop hardness of a ferromagnetic metal thin film such as Go-Ni is 1000CKy/mf'l, including the results of studies conducted under different conditions for the first and second layers of a nonmagnetic thin film.
The required film thickness is ferromagnetic metal thin film of about 3,000 from SOO, and the number of passes to reduce the S/N reduction to 2 dB or less is 6℃ to +50℃.
! To configure so times or more at 5%RH to so%RH, the Knoop hardness of the nonmagnetic thin film and protective film is 25001.
: Kg/-) or more.

220 when multilayering 3 to 6 ferromagnetic metal thin films
Although the target can be achieved even with a value of about 0 [Kq/-], it goes without saying that deterioration in image quality can be further prevented by setting the value to 26oOI:9/-] or more.

Effects of the Invention As described above, the present invention has the excellent effect of allowing high-density magnetic recording media to be replaced with little deterioration in reproduced image quality even after repeated use.

[Brief explanation of the drawing]

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. 5...Polymer film, 6.8...Nonmagnetic thin film, 7.9...Ferromagnetic metal thin film, 10.
·····Protective film.

Claims (1)

[Scope of Claim] A magnetic recording medium comprising a protective film arranged on a repeatedly laminated layer of a non-magnetic thin film and a ferromagnetic metal thin 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 being a thin film.