JPH0414611A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having excellent durability and C/N by incorporating a plate-type filler into a polymer film so that plate- type projections containing the filler as the core are formed on the surface of a magnetic recording layer. CONSTITUTION:The polymer film 1 such as polyethyleneterephthalate, polyethylenenaphthalate, etc., contains the plate-type filler 2. Projections 3 containing the filler 2 as the core are formed to <=200 Angstrom height, about 50 - 150 Angstrom height, with 0.3 - 1.5mum<2> area and 0.1 - 0.01 projection/mum<2> density. This filler 2 consists of oxides, nitrides, carbon, etc., and preferably, barium ferrite is used to obtain the plate-type surface of the projection. The magnetic recording layer 4 consists of Co-O, Co-Ni, etc., formed by an electron beam vapor deposition method, etc. Then a protective lubricating layer 5 and a back coating layer 6 are provided.

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 Efforts are being made to improve recording density in order to miniaturize and improve the performance of recording and reproducing equipment, and in recent years, it has been hoped that ferromagnetic metal thin films can be put to practical use as magnetic recording layers. [IEEE TRANSACTIONS ON MAGNETICS]
S ON k [AGNETIcs) Vol, M
A G-21No-3, P, P, 1217-1220 (
1985)). There are many possible combinations of materials for ferromagnetic metal thin films, but there are few that have been shown to be realistic possibilities.
No. 91, JP-A-61-120331] and Co
-Ni, Co-Ni-0, etc. obliquely deposited film or wet plating film [Japanese Patent Publication No. 41-19389, Japanese Patent Application Laid-Open No. 53-42
No. 010], etc., and for the purpose of practical application, the development of a protective lubricant layer has recently become the focus of investigation. Currently, coatings are applied directly onto polymer films such as polyethylene terephthalate films or after applying an undercoat such as fine particles.
A method in which a ferromagnetic metal thin film is deposited using electron beam evaporation or sputtering, and a solution of a lubricant such as fatty acid or perfluoropolyether dissolved in a solvent is applied directly to the surface and dried.
JP-A-57-179948, JP-A-61-178
718], disposing a lubricant through an oxide film [JP-A-61-15830], and a combination of a carbon film and a chlorocarbon system [JP-A-61-142525], etc. Although carbon films are still thick in magnetic disks, some of them have been put into practical use, and carbon materials have also been studied, and the usefulness of increasing hardness [US Pat. No. 471]
7622] has also come to be known.

Problems to be Solved by the Invention However, with the above configuration, it is difficult to improve both durability and C/N, and it is possible to ensure durable running performance by increasing density and improving spacing loss. There is a need for a magnetic recording medium with this configuration. The present invention was made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a magnetic recording medium that is excellent in both C/N and durability.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording medium of the present invention comprises:
The filler filled in the polymer film is plate-shaped, and plate-shaped projections with the filler as a core are reflected on the surface of the magnetic recording layer.

Function: Due to the above-described structure, the magnetic recording medium of the present invention has good uniform distribution of load even if the protrusion height is low, has improved durability, and has improved C/N.

Embodiments Hereinafter, embodiments of the present invention will be described in detail without reference to the drawings. FIG. 1 is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention. In FIG. 1, numeral 1 is a polymer film made of polyethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polyether ether ketone, polyimide, or the like. 2 is a flat filler, 3 is a protrusion with the flat filler as a core, and the height of the protrusion is preferably 200λ or less and 50 to 150 people,
The projection area projected from the top surface is in the range of 0.3μ2 to 1.5μ2, and the density is 0.1(ke/μ2) to 0.01(ke/μ2).
The range 2) is preferable. The material of the flat filler is not particularly limited, such as oxide, nitride, carbon, etc., but barium is the material that can easily make the protrusions formed on the surface of the flat filler into a flat shape. It is preferable to make it into a magnetic state such as ferrite and apply magnetic field orientation treatment technology.

4 is a magnetic recording layer, which is suitably made of a ferromagnetic metal thin film. Co-0, Co-Ni.

Electron beam evaporation films, sputtering films, etc. of Co-Cr, Co-Ni-Cr, Co-Ni-0, etc. are suitable. 5 is a protective lubricating layer, and 6 is a back coat layer. When implemented as a magnetic disk, 6 is not necessary, or when a double-sided access type is used, a well-known configuration may be used.

Examples of the present invention will now be described in more detail in comparison with comparative examples.

[Example 1] Barium ferrite (hexagonal plate shape) was filled inside a polyethylene terephthalate film with a thickness of 10 μm,
A conductive coil is used to orient the surface to form a surface with different plate-like protrusion conditions, and on top of that, C0Ni (Co 80wt%) is placed along a cylindrical can with a diameter of 1m, with a minimum incidence angle of 30 degrees.
A 0.16 μm Co-Ni0 magnetic recording layer was formed by electron beam evaporation in oxygen at X 10−5 (Torr), and 5OA of barfluorostearic acid was applied thereon to form a 0.4 μm back coat layer. (composed of carbon, calcium carbide, and polyurethane resin), and was made into an 8 mm wide magnetic tape.

In the comparative example, 20 (ke/μ2) of SiO2 fine particles with diameters of 100 and 200 were placed on an ultra-smooth (average roughness 30) polyethylene terephthalate film with a thickness of 10 μm, and the same Co- A Ni-0 film, a lubricant, a back coat layer, and a tape having a width of 8 mm was used.

Each tape was recorded on an 8mm video (EV-8900 Sony ■
Table 1 summarizes the results of a comparative evaluation using the following methods.

(Left below) [Example 2] Another means for solving the problem was to deposit an oxide film on a coating layer of spherical fine particles arranged on a polymer film by oblique sputter deposition with an incident angle of 60 degrees or more. A ferromagnetic metal thin film is arranged on the ferromagnetic metal thin film.

The magnetic recording medium of the present invention has the above-described structure, so that even if the spherical fine particles are made small, shape anisotropy is produced in the diagonal snow/vine deposited film, and the adhesion strength is increased without shadowing due to sputtering energy. Therefore, even if the protrusion height is low, the friction characteristics are improved due to the shape effect, and the C/N and durability are also improved.

FIG. 2 is an enlarged sectional view of the magnetic recording medium of the second embodiment. In FIG. 2, 7 is a polymer film such as polyethylene terephthalate or polyphenylene sulfide, preferably having an average surface roughness of 40 Å or less. 8 is 5
i02. Fine particles such as TiO2, Zr02A1203, etc.
A sphere of 50 to 100 people is preferred. Reference numeral 9 is an oxide thin film formed by oblique sputter deposition, and it does not necessarily have to be a perfect oxide film in terms of stoichiometry. The point is that the shape anisotropy caused by oblique sputter deposition is emphasized by performing sputter deposition without introducing oxygen, and the wraparound effect increases adhesion strength. It is preferable that the angle of incidence is 60 degrees or more. If the size of the spherical particles is large, can the angle be less than 60 degrees?As shown in Figure 3, if the spherical particles are
It can be said that it is preferable to select this condition because the stability of the dynamic friction coefficient can be obtained by setting the angle to 60 degrees or more when the friction coefficient is the minimum).

Other components may be those described in the first embodiment.

The second example will be described in more detail below in comparison with a comparative example.

Various spherical fine particles were coated on a 9 μm thick polyethylene naphthalate film (average surface roughness of 25 mm), placed along a 50 cm diameter cylindrical can, and the minimum incident angle was changed while introducing oxygen. An oxide film of
(Co 80yt%) was deposited using an 850-person electron beam at a minimum incident angle of 30 degrees, which was repeated twice to form two layers of Co-N.
Form an i-0 film, further target graphite on it, Ar + H = = 0.07 (Torr),
Ar: H:= 1・3,300 (KHz),
Sputtering was performed using a glow discharge of 1.2 (KW), and 100 hard carbon films were placed on top of the sputtering, followed by perfluoropolyether "Vonprin Z-" manufactured by Montegisson.
25" was coated at 30 (w/nf), and a back coat layer of 0.
A magnetic tape with a width of 8 mm was made by disposing 4 m of films. Comparative examples used were one in which an oxide film was formed by electron beam evaporation at an incident angle of 60 degrees, and one without an oxide film.

Table 2 shows the conditions and evaluation results. The evaluation equipment used was the same as shown in Table 1.

In addition, Figure 3 shows 5iO2 (50 person diameter) at 30 cases/μ2.
The graph shows a comparison of changes in the coefficient of dynamic friction when the same ferromagnetic metal thin film and protective lubricant layer □ as in the example were used, and the conditions of oblique incidence were changed (the film thickness was constant at 450 people).

From FIG. 3, it can be seen that the stability is better when the angle of incidence is 60 degrees.

(Hereinafter referred to as a margin) Effects of the Invention As described above, the present invention has the excellent effect of providing a magnetic recording medium with excellent durability and C/N ratio.

FIG. 3, an enlarged cross-sectional view of the recording medium, is a diagram showing the relationship between oblique sputter deposition conditions and the stability of the coefficient of dynamic friction.

2... Flat filler 4... Magnetic recording layer, 8... Spherical particles, 9... Oblique sputter deposited oxide film.

Name of agent: Patent attorney Shigetaka Awano and 1 other person Flat board 1 large filler diagram O 4ρ 6ρ 8ρ Chakoiriyoi 1 ryo C counterfeit)

Claims (2)

[Claims] (1) A magnetic recording medium characterized in that a filler filled in a polymer film is plate-shaped, and plate-shaped protrusions centered on the filler are reflected on the surface of the magnetic recording layer. (2) A magnetic recording medium characterized in that a ferromagnetic metal thin film is disposed on an oxide film formed by oblique sputter deposition on a coating layer of spherical fine particles disposed on a polymer film.