JPS6314325A - Magnetic recording medium for perpendicular magnetic recording - Google Patents

Abstract

PURPOSE:To improve mechanical durability and electromagnetic conversion characteristic by disposing a nonmagnetic low melting metal having <=65 deg.C m.p. by segregation and deposition to the circumferential surface of ferromagnetic acicular particles and enclosing the circumference of such acicular particles with a polymer. CONSTITUTION:The CoCr acicular particles 2 are formed on a substrate 1 perpendicularly to the plane of the substrate 1 and a deposited layer 3 of Bi is disposed around the acicular particles 2. A layer 4 of PE is packed between the acicular particles enclosed by Bi. The CoCr acicular particles are magnetically insulated from each other by the Bi layer segregated and deposited on the surface of the CoCr acicular particles and are further insulated by the PE layer 4 so that the respective acicular particles maintain excellent magnetic characteristics as a single domain particle even if the packing rate of the CoCr acicular particles is high, according to the composite CoCr-Bi-PE films. The stress to be exerted to the acicular particles by sliding with a magnetic head is relieved by the pressure of the PE layer 4, by which the mechanical durability and particularly sliding resistance of the recording layer are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium, particularly to a magnetic recording medium having magnetic anisotropy perpendicular to a substrate surface.

[Conventional technology]

As a magnetic recording medium, γ-F-xO is deposited on a non-magnetic substrate.
γ-Fagot doped with s, co, F-xO-1
Coating in which a magnetic material such as C, Oz or ferromagnetic alloy powder is dispersed in an organic binder such as vinyl chloride-vinyl acetate copolymer, styrene-butadiene copolymer, epoxy resin, polyurethane resin, etc., and then dried. However, with the recent increase in demand for high-density recording, ferromagnetic metal r4
Magnetic recording media in which a film is formed on a substrate are attracting attention.

As this type of medium, C, C, alloy thin films, C, Ni, C, R, C, O, etc. have been mainly studied, and high density recording has become possible. In such non-binder type magnetic recording media, a ferromagnetic metal with a saturation magnetic flux density (Bs) higher than that of an oxide is formed as a thin film without containing a non-magnetic material such as a binder, so it is difficult to achieve high-density recording. It has the advantage that it can be made ultra-thin.

However, since it is a continuous magnetic thin film, when magnetic recording is performed, a tIA tooth-shaped magnetization transition region is generated, and high-density recording corresponding to a recording wavelength less than the width of this magnetization transition region is impossible.

In order to solve the above problems, we use a metal thin film type medium in which a ferromagnetic material is formed to have magnetic anisotropy in a direction perpendicular to the substrate, so that the recorded magnetization exists in a direction perpendicular to the substrate. Perpendicular magnetic recording method was developed. However, important problems still remain in putting these metal thin film media into practical use.

First of all, compared to conventional coated media containing binders, they are more likely to be scratched by the sliding of the magnetic head and have lower mechanical durability.Secondly, the flexibility of organic polymer films, etc. If a thin metal film like the one described above is provided on a substrate rich in magnetic flux, the flexibility of the recording medium will be poor, making stable contact between the magnetic head and the surface of the recording medium difficult.

To avoid these problems, 13a in organic binder
Some attempts have been made to form a perpendicular magnetic recording layer by dispersing and coating fluorite S particles, but since the magnetic powder is an oxide in this method, the saturation magnetization is small and the dispersibility of the magnetic powder is limited. However, there is a problem that the filling rate of magnetic powder in the magnetic layer cannot be sufficiently increased, and as a result, the reproduction output is considerably lower than that of the metal thin film type media.

Furthermore, as described in Japanese Patent Publication No. 57-3137, a strong 6n material such as a ferromagnetic metal and a polymer are simultaneously deposited on a substrate, and ferromagnetic particles with a large saturation magnetic flux density (BS) A polymer composite membrane structure has been proposed. However, in magnetic recording media with such a structure, in order to ensure insulation between each ferromagnetic particle and maintain high-density recording performance, the filling ratio of ferromagnetic particles cannot be made too high. , the improvement of playback output is limited.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, in order to ensure that each particle behaves like a single-domain particle, there is a limit to increasing the filling rate of the ferromagnetic particles deposited on the substrate. Then, there was a problem that the characteristics as a high-density recording medium were impaired.

The present invention solves the above problems of the prior art, eliminates the poor mechanical durability against sliding of the magnetic head and the poor contact with the magnetic head, and provides a magnetic recording medium with excellent electromagnetic conversion characteristics. The purpose is to

[Means for solving problems]

The above purpose is to simultaneously deposit a polymer, a ferromagnetic material, and a non-magnetic low melting point metal using a physical vapor deposition method, so that the ferromagnetic scale particles are dispersed in the polymer perpendicular to the surface of the substrate or at a certain angle.・Achieved by oriented and non-magnetic low melting point metal segregates and precipitates on the surface of ferromagnetic meter-shaped particles to form a non-magnetic layer.

[Effect]

With the above structure, each ferromagnetic meter-shaped particle is magnetically insulated by the presence of the low melting point nonmagnetic layer and polymer on the particle surface. As a result, even if the filling rate of ferromagnetic particles is high, each particle exhibits single-domain particle behavior,
Shows excellent magnetic properties. In addition, since the polymer has a structure in which the ferromagnetic needle-shaped particles are surrounded by a polymer, when a magnetic head slides on the surface of the magnetic recording medium, the ferromagnetic needle-shaped particles maintain the mechanical strength of the recording layer and become acicular. The polymer surrounding the particles relieves the stress applied to the acicular particles by sliding of the magnetic head, resulting in extremely excellent mechanical durability, particularly sliding resistance, of the recording layer.

Note that the ferromagnetic material that can be used in the present invention is F@+Co.

Targets include N+ or alloys of these 3d transition metals with various elements, oxides including γ-F-tos, or nitrides. Furthermore, the polymers referred to in the present invention include polyethylene, polyethylene terephthalate, polypropylene, polystyrene, and polytetrafluoroethylene.

polybutadiene, polycarbonate, polyamide.

It refers to organic polymer materials such as polyimide, polyvinyl chloride, polyvinyl acetate, and polyurethane, and non-magnetic low-melting metals with a melting point of 650°C or less include Bl, P, and S.
, , Z, , etc. However, in this case, the composite film of the polymer, ferromagnetic material, and non-magnetic low melting point metal does not necessarily need to constitute a complete polymer film, and monomers, oligomers, telomers, etc. Even if mixed,
This does not significantly affect the effects of the present invention.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram of the structure of a magnetic recording medium for perpendicular magnetic recording according to the present invention, where l is a base film of polyethylene terephthalate (PET) as a substrate, and 2 is a needle-shaped ferromagnetic material C. The particles 3 are a deposited layer of B, which is a non-magnetic low melting point metal, and 4 is a polyethylene layer as a polymer.

In the figure, acicular particles 2 of C, C, are formed perpendicularly to the surface of the substrate 1 on a substrate 1, and a precipitated layer 3 of B is arranged around the acicular particles 2. Furthermore, a layer 4 of polyethylene is filled between the acicular particles surrounded by Bl. Note that the acicular particles 2 are arranged perpendicularly to the substrate surface, but depending on the type of recording signal, the acicular particles 2 may be arranged perpendicularly to the substrate surface.
As shown in FIG. 2, it may be formed at a certain angle on the substrate surface.

That is, according to the C-Cr B+ -polyethylene composite film shown in FIG. By being insulated by the polyethylene layer 4 and further insulated by the polyethylene layer 4, each acicular particle maintains excellent magnetic properties as a single domain particle even if the filling rate of the C0C and acicular particles is high. Furthermore, the presence of polyethylene N4 can alleviate the stress applied to the acicular particles by sliding of the magnetic head, and can improve the mechanical durability of the recording layer, especially the sliding resistance.

FIG. 2 is a schematic configuration diagram of a bunku vapor deposition apparatus for explaining the manufacturing method of a magnetic recording medium for perpendicular magnetic recording according to the present invention, in which 5 is a delivery roll, 6 is a take-up roll, 7 is a can, and 8 is a is the hearth for C0C, 9 is the hearth for B1, 1
0 is a polyethylene boat, and 11 is a mask.

In the figure, a PET film 1 serving as a base is sent along a route from a delivery roll 5, around a can 7, and to a take-up roll 6. Below the can 7 is a hearth 8. Bt hearth9. A polyethylene boat 10 is arranged, and C, C, B+, and polyethylene are stored in each boat.

The can 7 is heated and maintained at a predetermined temperature, for example, 50° C., the C, C, and B lengths are heated by electron beam heating, the polyethylene is heated by resistance heating, etc., and the vapor deposition operation is performed in a vacuum. In addition, C, C,.

B5. Polyethylene vapor is deposited on the surface of the substrate 1 through the window 12 made by the mask 11.11 provided around the can 7.

The PET film 1 that is the base has a thickness of, for example, 12 μm, and C, C, are Co*oCrto (w t ).

%), and the polyethylene content was 30vol. %.

The PET base film 1 supplied from the delivery roll l is heated in a can 7 kept at 50°C, and is heated by a mask 11
．． C, C, B, polyethylene are simultaneously deposited in 11 windows. At this time, C, C.

The mask 11.11 is adjusted and the window 12 is positioned so that the incident angle of the steam is 20 degrees and the exit angle is 20 degrees.

The magnetic recording medium for perpendicular magnetic recording thus formed has a structure as shown in FIG.
On the surface of the 00Cr acicular particles 2 grown on them, B+ 3, which does not form a solid solution with them, segregates and precipitates, and C, C, and the acicular particles are magnetically insulated.

Then, a polyethylene layer 4 surrounds these C, C, and acicular particles, magnetically insulating the C, CP, and acicular particles as in 8.3, and at the same time alleviating the stress when the magnetic head slides. This significantly improves the durability and abrasion resistance of recording media. Note that the thickness of this composite membrane is 500 to 5000. Table 1 shows the durability evaluation test results of the perpendicular magnetic recording medium thus prepared by a spherical sliding test.

From Table 1, it can be seen that the durability was less than 100 passes when the polymer was not included, but when the polymer was used at 5 vol.

It can be seen that by containing % or more, the durability is greater than 1,000 pulses.

Table 1 FIG. 3 shows C0 of a 6n recording medium for perpendicular magnetic recording according to the present invention. -C, to B+- This is a magnetic characteristic diagram of a polyethylene composite film (polyethylene content 30 vol, base temperature 50°C), in which the horizontal axis is B, (wt.

%) and He (±)○ on the vertical axis to show the relationship between the content of B and Hc (1). In the same figure,
The content of B1 and He C±] are almost proportional, and when B is not added, H6 is approximately 20,008;
, it can be seen that He increases as .

Next, the nonmagnetic low melting point metal layer 3 represented by B above will be explained.

As shown in FIG. 1, the ferromagnetic acicular particles (C0C,) of the magnetic recording medium formed on the base film (substrate) 1 exhibit ferromagnetism as a C, -C, alloy. The non-magnetic metal that is segregated and precipitated on the surrounding surface of the acicular particle to magnetically insulate it must not form an alloy with the ferromagnetic recording alloy. It is necessary that the layer exists as a single unit on the peripheral surface of the acicular C, C, particles.

Furthermore, in order for ferromagnetic particles such as C, C, etc. to be formed on the substrate l, the temperature of the can 7 in FIG. 2 must be maintained at a low temperature of 50'C. is necessary.

Furthermore, since the PETl base material and the polymer filled between the acicular particles are deformed at high temperatures, a material with a high melting point cannot be used as the non-6n metal material of the In magnetic insulator.

As a result of studying these conditions, the present inventors discovered that a nonmagnetic metal with a melting point of 650° C. or lower is suitable as the nonmagnetic metal to be employed.

Non-magnetic gold 5 that satisfies this condition includes the above-mentioned B,
In addition to , P, , S, , Z, etc. can be mentioned.

Figure 4 shows COC segregated and precipitated on the substrate according to the present invention.
, +a+ composition diagram showing the formation status of B and l formed on the acicular particles and their surrounding surfaces, and as shown in the same figure (bl), C, C, and B1 layer are formed on the surrounding surfaces of the acicular particles. The graph shows the results of measuring the composition distribution in the depth direction (arrow) using Auger analysis for segregated and precipitated materials.

According to the figure, the acicular particles of C, C, alloy have a high Co4 degree in the center, and C, ? It can be seen that Ha is high and B and N are segregated and precipitated outside C7.

(Effects of the Invention) As explained above, according to the present invention, by simultaneously depositing a polymer, a ferromagnetic material, and a non-magnetic low melting point metal layer that does not form a solid solution with the ferromagnetic material by a physical MW method, The ferromagnetic meter-shaped particles are dispersed in the polymer at an angle of The 6FFF gas medium exhibits excellent magnetic properties by being insulated from the outside, and also improves durability by neutralizing the stress received when sliding with the polymer head. can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the structure of a magnetic recording medium for perpendicular Ei recording according to the present invention. FIG. A schematic configuration diagram, FIG. 3 is a magnetic characteristic diagram of the recording medium for perpendicular magnetic recording according to the present invention, and FIG. 4 is a composition diagram showing the formation status of C, C, and acicular particles and the Bl layer formed on the surrounding surface thereof. It is. 1...Base film, 2...Ca Cr acicular t
h child, 3...Bl, 4..., polyethylene, 5.
...Feeding roll, 6...V removal roll, 7...
・Can, 8...C0 vapor deposition hearth, 9...Bl vapor deposition hearth, 10...Polyethylene vapor deposition boat, 1
1...mask, 12...window. Fig. 1 2.2'-COCr (f47'n+ 3-----B1 4-----'; r: lienalene Fig. 2 11 to Fig. 3 HcC top) CoaoCr2o-Bi-polyethylene i (,t
''Anal tyrene content base 30VOR% board 58cm 50'C
') contains Bj! and) fc(1). Fig. 4 Spar 79 hours ALJQerke 6 distribution in moat direction (spack speed loλ/geli (b) 00A

Claims (1)

[Claims] 1. A magnetic recording medium for perpendicular magnetic recording comprising a non-magnetic substrate, ferromagnetic meter-shaped particles having an axis of easy magnetization perpendicular to the surface of the substrate or in a certain angular direction, and a polymer, in which the ferromagnetic meter-shaped particles A magnetic recording medium characterized in that a nonmagnetic low melting point metal with a melting point of 650° C. or less is segregated and precipitated on the peripheral surface of particles, and the acicular particles are surrounded by a polymer.