JPS6126924A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having a good S/N ratio and excellent runnability, resistance to scratching, etc. by coating and fixing particles for forming projections on a high-polymer substrate and forming a thin magnetic film layer in lamination with a soft magnetic layer and vertically magnetizable film or a single layer of isotropically magnetizable film thereon. CONSTITUTION:The particles 8 of ZnO, MgO, SiO2, CaCO3, etc. having about 170-350Angstrom average particle size are coated and fixed onto the high-polymer substrate 7 consisting of polyamide, etc. to about 6-35 pieces/mu<2> density with an epoxy resin, etc. as a binder. The magnetic layer 9 is formed on such substrate 7 by which a magnetic recording medium having the projections 10 is obtd. The projection rate = the number density of the projections/the number density of the particles is made <=4/5. The layer 9 may be the lamination type formed with the vertically magnetizable film on the soft magnetic layer or the single layer type of a longitudinally magnetizable film, isotropically magnetizable film, etc. The magnetic recording medium having the good S/N ratio and the improved still durability, runnability, durability, etc. is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording medium suitable for high-density magnetic recording.

Structures of conventional examples and their problems In recent years, magnetic recording has rapidly increased in density, and the use of so-called coated media, in which fine ferromagnetic particles are dispersed and fixed on a polymer substrate using a binder, has reached its limit. It is now generally recognized that this is close, and there is an increasing need to put into practical use so-called metal thin film magnetic recording media that do not have a binder and are suitable for high-density recording.

In particular, as shown in FIG. 1, in a so-called perpendicular magnetic recording medium, which is formed by laminating a soft magnetic layer 2 and a perpendicularly magnetized film 3 on a polymer substrate 1, the higher the density, the more negligible the demagnetizing field becomes. ,Attention has been paid.

FIG. 2 is an enlarged schematic diagram of the main parts of a magnetic recording medium based on a proposal to improve the practical performance, especially the scratch resistance, of the metal thin film type shown in the example shown in FIG. By disposing fine particles 6 on top and forming a magnetic layer 6 thereon, the contact area becomes smaller, and the effect of improving running performance and scratch resistance is clearly seen.

However, even if a perpendicular magnetic recording medium or a longitudinal recording medium is obtained based on such a configuration, there is a problem that a sufficient signal-to-noise ratio (S/N) cannot be obtained.

Magnetic recording media with smooth substrates, which were conventionally considered ideal, are not at a level that can be put to practical use in terms of scratch resistance, runnability, etc., so S /N problem is important to solve.

Purpose of the Invention The present invention has been made in view of the above circumstances.
The object of the present invention is to provide a magnetic recording medium having good properties and improved durability.

Structure of the Invention The magnetic recording medium of the present invention is characterized in that the density of the protrusions of the magnetic thin film formed on the polymer substrate is 4/5 or less of the density of the basic particles. Toshi S
/N is good, and durability such as runnability and scratch resistance is improved.

Description of examples The present invention will be described below with reference to the drawings.

FIG. 3 is an enlarged schematic diagram of the main parts of the magnetic recording medium of the present invention, in which 7 is a polymer substrate, 8 is a basic particle, 9 is a magnetic layer, and 1o is counted as a protrusion.

As shown in FIG. 3, the schematically illustrated magnetic layer 9 is configured so that the density of the protrusions 10 that appear under the influence of the basic particles 8 is smaller than the basic particles, and the critical condition to be satisfied is 213 or less. The key point is to do so.

With this configuration, even if the magnetic layer is laminated with a soft magnetic layer,
Alternatively, a perpendicularly magnetized film, a longitudinally magnetized film, or an isotropically magnetized film may be used alone.

The critical condition is the minimum S/
This was determined experimentally when N was assumed to be 46 dB, and the reason for the reduction in noise is that regardless of the manufacturing method, the angle of incidence of atoms on the substrate differs microscopically by 1 h. This is thought to be due to the reduction in magnetic non-uniformity that occurs.

Polymer substrates used to construct such media include polyesters, polyolefins, polycarbonates,
Cellulose derivative, polyamide.

It includes polyimide, etc., but it also includes those with particles added inside and those with a cloak structure on the surface.

The fine particles that can be used in the present invention are ZnO.

MgO, Aβ2J, SiO2, TiO2', MgCO
3゜CaCO2, caso4. The scope of the present invention also includes the use of BaSO4, etc., alone, in combination, or in combinations of sizes used.

The soft magnetic layer formed on this is, for example, Ni-Fe.

Mn-Ni-Fe, Mn-Zn-Ni-Fe, etc.
The ferromagnetic layer is Go, Fe, Co-Ni, -G
o-Ti, Co-8n, Go-Mo.

Go-W, Co-Cr, Co-Ru, Co
-V, Co-Mg.

It does not depend on the direction of the easy axis of magnetization in Go-0, Co-Ni-0, co-Ni-P, etc.

Although no general rule has been found for obtaining the structure of the present invention,
Once the material is determined, it can be determined experimentally by adding a small amount of gas during vapor deposition, controlling the substrate temperature, etc., depending on the material. Among them, the most effective method is to effectively
In a thickness region of 00 Å or less, diagonal deposition is performed at an angle of 70 degrees or more, and then vertical deposition is performed, or diagonal deposition is performed from the opposite angle.

A specific example of a magnetic recording medium provided with a perpendicularly magnetized film having a soft magnetic layer, which has a particularly remarkable effect on noise reduction, will be described in detail.

(Example) Fine particles were coated and fixed as basic particles on a polyamide film having a thickness of 10 μm. Epoxy resin was used as the resin.

Before depositing a 0.3 μm thick Ni-Fe (Fe 20 wt, 96 ) film on top of this, a Ti film was applied at an angle of incidence of 70 degrees or more.
Formed a person. At that time, the temperature of the substrate film was changed from 76℃ to 215℃, and the degree of vacuum was evacuated to 1O-8Torr, and then the temperature was changed from 1×1o'Torr to 4×10Torr.
The introduction of CO gas was controlled until the end. The N1-Fa film was formed by vertical deposition with an incident angle of 10 degrees or less, and the film temperature was 166°C.
The temperature was kept constant at ℃. A QO-(:r film with a thickness of 0.1 μm was formed thereon by high-frequency sputtering.

The number of basic particles and the number of protrusions can be set to an arbitrary number using a scanning electron microscope.
Measurements were taken at 0 locations and the average value was used for evaluation.

The S/N is a wavelength of 0.31 μm, a track width of 7 μm, and the main magnetic pole is a Co-B based amorphous sputtered film with a thickness of 0.16 μm.
It is.

The perpendicular coercive force of the Co--Cr film varies slightly depending on the tape, but falls within the range of 10QO [Oe] to 1040 [Oe].

The various constants and characteristics of the obtained tape are shown in the table.

*1 Still characteristics are measured by the time it takes for the output to decrease by 3 dB from the initial state using a rotating helical scanning video head (Go-B amorphous head) (the test environment was 4 dB).
0″G93%FIH).

*2 The coefficient of dynamic friction is shown as the change before and after running when a prototype video tape recorder was run 350 times at 40°C and 93% RH.

From the table, it can be seen that the structure of the present invention has a good balance between S/N and durability.

The magnetic recording medium of the present invention can achieve the same or similar performance to that shown in the examples even when the other materials mentioned above are combined, and it is effective not only for magnetic tapes but also for magnetic disks and sheets. be.

Effects of the Invention The magnetic recording medium of the present invention has improved S/N ratio and practical durability by making the protrusion density of the magnetic recording layer 4/5 or less lower than the density of the basic particles on the substrate. It can maintain the level, and its practical effects are significant.

[Brief explanation of drawings]

1 and 2 are schematic cross-sectional views of a conventional magnetic recording medium, and FIG. 3 is a schematic enlarged cross-sectional view of the magnetic recording medium of the present invention. 7...Polymer substrate, 8...Basic particle, 9
...Magnetic layer, 1o...Protrusion. Name of agent: Patent attorney Toshio Nakao - 11 people Figure 1

Claims (1)

[Claims] The density of the protrusions of the magnetic thin film formed on the basic particles that form protrusions on the polymer substrate is 4/5 of the density of the basic particles.
A magnetic recording medium characterized by the following: