JPS63144406A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve a still characteristic and S/N at the time of short wavelength recording and reproducing by disposing a thin Bi-S film on a high- polymer film and laminating a thin ferromagnetic metallic film and lubricating layer thereon. CONSTITUTION:After the thin B-S film 2 is disposed on the high-polymer film 1, the thin ferromagnetic metallic film 3 and the lubricating layer 4 are laminated thereon. The high-polymer film 1 consists of PE terephthalate, PE naphthalate, etc., and the thin Bi-S film 21 is formed by a high-frequency sputtering method using, for example, Bi2S3 as a target or is obtd. by a method for introducing H2S as gas and depositing Bi by evaporation under glow discharge. The thin ferromagnetic metallic film 3 consisting of Mn-Bi, Co-Ni, etc., is formed by an electron beam vapor deposition method, ion plating method, etc. The lubricating layer 4 consists of a fatty acid, fatty acid ester, fluorine compd., etc., alone or a mixture composed thereof or may be a combination thereof with amorphous carbon and plasma-polymerized film.

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 Magnetic recording media whose magnetic recording layer is a ferromagnetic metal thin film such as Go-N or Go-Or have attracted attention as high-density recording media, and their excellent high-density recording performance has been demonstrated. ing. However, when compared with coated magnetic recording media, the runnability and wear resistance of metal thin films are still far from satisfactory. Therefore, various protective lubricant layers have been studied in order to simultaneously improve the above two problems, but the problem that the thickness of the protective lubricant layer is large and causes a spacing loss still remains. [JP-A-64-113303, JP-A No. 56-143540, JP-A No. 468-133631,
No. 58-146027.

61-120331, etc.] On the other hand, methods of solving the above problem by changing the shape of the magnetic recording layer itself have been studied [JP-A-59-92427, U.S. Patent No. 4,56.
No. 4,549, etc.], this shape effect and the above-mentioned improvement of the protective lubricant film have led to improvements in practicality.

Problems to be Solved by the Invention However, with the above configuration, when high-density digital recording is intended, the error rate is unstable and improvements are desired. In particular, the types of protective lubricants are limited and the types of protective lubricants required are limited, especially when trying to satisfy the durability performance that disk-shaped media and media that can be applied to the rotating helical scan method, especially the still characteristics that reproduce the same track repeatedly. Improvements have been desired since the amount of lubricant increases, the spacing loss increases, and the signal-to-noise ratio (hereinafter referred to as S/N) decreases. 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 with improved still characteristics and S/N maintained at a practical level.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording medium of the present invention has a Bi-S thin film arranged on a polymer film, and then a ferromagnetic metal thin film and a lubricating layer laminated thereon. This is what I did.

The magnetic recording medium of the present invention has the above-described configuration, and the magnetic properties of the ferromagnetic metal thin film are improved, particularly in the squareness ratio in the case of an in-plane magnetized film, and in particular in the perpendicular anisotropy of the magnetic properties in the perpendicularly magnetized film. In addition to improving short wavelength output and improving S/N, some constituent elements of the underlying Bi-8 thin film are partially unevenly distributed on the surface due to grain boundary diffusion of columnar fine particles during the formation of the ferromagnetic metal thin film. Therefore, the magnetic recording layer is less likely to be destroyed under extreme pressure, the lubricant can be made thinner, the spacing loss is small, and good S/N characteristics are maintained.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an enlarged sectional view of a magnetic recording medium according to a first embodiment of the present invention. In Figure 1, 1 is a polymer film such as polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polysulfone, polycarbonate, polyphenylene sulfide, cellulose acetate butyrate, boria i-toimide, polyimide, etc., and 2 is a Bi-3 thin film. For example, it can be formed by high frequency sputtering using Bi2B5 as a target, or H2S
It is obtained by introducing Bi as a gas and depositing Bi in a glow discharge, and the atomic ratio of Bi and S is Bi.
A range of /S = 0.1 to 0.5 is appropriate from the standpoint of both improving magnetic properties and improving durability.

When Bi/S exceeds 056, durability decreases, and B/S
If it becomes 0.1 or less, the magnetic properties deteriorate, so an appropriate range is determined. Of course, the above should be taken as a guideline, and if the magnetic recording layer is made of an in-plane magnetization film or a perpendicular magnetization film, or if the necessary electromagnetic conversion characteristics are obtained, it is important to focus on improving durability. You can make adjustments as appropriate, such as by placing . The Bi-S thin film is preferably selected to have an average thickness of 200 Å or less to 20 Å or less. This is partly because the unevenness effect is useful for improving durability, and partly because when the thickness exceeds 200 Å, the adhesion strength may decrease. 3 is Mn-Bi.

Go-Ni, Go-Cr, Go-Mo, G
o-W, Go-Ti.

Go-Ta, Go-Ru, Fa-Ag, Go-3
m.

Go-Fe, Co-Pt, Go-Rh, G
o-0, Go-Os.

Go-Ni-0, Co-0r-Nb, Go-Ni-
Cr.

A ferromagnetic metal thin film such as Go-Mn-Bi is formed by an electron beam evaporation method, an ion blating method, an ion beam deposition method, a Suhasota2N/G method, or the like. Reference numeral 4 denotes a lubricating layer, which may be made of a fatty acid, a fatty acid ester, a fluorine compound 2, etc., alone or in combination, or, if necessary, in combination with amorphous carbon or a plasma polymerized film.

FIG. 2 is an enlarged cross-sectional view of a magnetic recording medium according to a second embodiment, and elements in FIG. 2 that may be common to those described in the first embodiment are given the same numbers. @2 In Figure 5, 5 is an undercoat layer, which has fine protrusions on the magnetic recording layer to further improve durability. 5i02, J! 20s
, Carbore Inorganic fine particles such as CaCO3 and BaSO4,
Polyvinyl acetate, polyurethane.

Polyisoprene, acrylonitrile, butadiene copolymer, polystyrene, polyacrylonitrile.

Among organic fine particles such as polymethyl methacrylate and polyester, particles with a diameter of about 60 to 200 deer were selected and dispersed at a rate of about 0.1 to 100 particles/(μm)2.
It is composed of something fixed on a polymer film with a resin, a worm-like protuberance of a water-soluble polymer, or a combination of a worm-like protuberance and the above-mentioned fine particles. 2 and 3.4 to be laminated on top of this are those described in the first embodiment, and the optimum combination may be selected.

Hereinafter, more specific examples will be described in comparison with comparative examples. 1 while introducing H2S at a rate of 5 (l/min) onto a polyethylene terephthalate film with a thickness of 10 μm.
A high frequency glow discharge of 3.56 (MHz) is generated,
Bi was evaporated and a Bi-8 thin film was formed by 70 people (actually, unevenness was formed in terms of uniform film thickness, and the height of the unevenness was 90 people). Bi/S was set at 0.23. On top of that, Go-Ni is placed along a 1m diameter circular can
(Ni, 20 wt%) at 3.5X10-5 (To
Electron beam evaporation was performed in oxygen with a minimum incidence angle of 45 degrees. The coercive force of the Go-Ni-0 film with a thickness Q of 15 μm was 1060 (Os), and the squareness ratio was 0.92. 13 pieces/μ
m) After fixing with 2 polyester resin, 4 Bi-8 films were applied using the same method as the tape film (Bi/S = 0
．． 34) and a Go-Or perpendicular magnetization film (O
r20wt%) 0.13 μm by high frequency sputtering method (Tape B).

A Bi-S thin film was placed on the film with the 5i02 fine particles used in Tape B, a Go-Ni-0 film, and a Go-Ni-0 film.
A Go-Cr film was formed under the same manufacturing conditions. The coercive force of the obtained Go-Ni-0 film was 9ss (Os), the squareness ratio was 0.74 (tape C), and the coercive force in the vertical direction of the Co-Cr film was 490 (Oe). (Tape D). The retention strength of the Go-Cr film of Tape B was 600 (Oe).

Tapes A to D were commonly formed using a vacuum evaporation method to form perfluorooctanoic acid as a 70-layer lubricant layer to form magnetic tapes with a width of 8 mm.

Recording and reproduction using a ferrite head with a gap length of 0.2 μm and still characteristics were compared. The playback output at a recording wavelength of 0.75 μm is 14 (dB) larger than Tape C.
The S/N ratio is 1 (dB) good, and the still characteristics are compared based on the time it takes for the output to drop by 2 dB from the initial level.
Tape Person was 83 minutes long and Tape C was 47 minutes long.

The reproduction output of tape B at a recording wavelength of 0.5 μm is 3.7 (dB) higher than that of tape D, and the S/N is 2.4 (
dB) good and methyl characteristics are 56 minutes for tape B and tape D
was 22 minutes, and it was found that each of the examples was superior in both the S/N still characteristics. Effects of the Invention As described above, according to the present invention, the still characteristics and the S/N during short wavelength recording and reproduction are superior. In both cases, an improved magnetic recording medium can be obtained, which is an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a magnetic recording medium according to a first embodiment of the invention, and FIG. 2 is an enlarged sectional view of a magnetic recording medium according to a second embodiment of the invention. 1...Polymer film, 2...Bi
-S thin film, 3...Ferromagnetic metal thin film, 4...
- Lubricating layer, 6...Undercoat layer. Name of agent: Patent attorney Toshio Nakao and 1 other person
・-Polymer film

Claims (1)

[Claims] A magnetic recording medium comprising a Bi-S thin film disposed on a polymer film, a ferromagnetic metal thin film, and a lubricating layer laminated thereon.