JPS59201216A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a high-performance tape having high residual magnetizm, coercive force and squareness and a small characteristic change with a temp. change by dispersing fine particles of an ''Alnico'' magnet alloy consisting essentially of Al, Ni and Co in a binder and subjecting the same to a magnetic field orientation thereby manufacturing the magnetic tape. CONSTITUTION:A magnet alloy consisting essentially of Co, Ni and Al, and contg. a small amt. of Cu or Ti, etc. and the balance Fe is made by combining the compsn. and aging conditions and the alloy is pulverized to about 0.2mu to manufacture magnetic powder having various characteristics and the characteristics meeting requirements. Such fine magnetic particles are uniformly dispersed in a binder and are subjected to a magnetic field orientation, thereby manufacturing a magnetic tape. The high-performance tape having high residual magnetizm, high coercive force and squareness and a small characteristic change with a temp. change is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic material for magnetic recording tape.

Generally, in order to increase the output, recording density, and sensitivity of a magnetic tape, a magnetic material is required to have a large residual magnetization, a high coercive force, and a high squareness of the magnetization curve. Currently, a coercive force of about 200 to 10,000 e is generally used, but it is thought that as the performance of magnetic beds improves, there will be a trend toward higher coercive forces.

Oxides and metals are used as magnetic materials. Since the saturation magnetization of metals is about 2 to 4 times higher than that of oxides, magnetic tapes with high output and high recording density can be obtained.

As metals, Fe-Co alloy and Co-N1-P
alloys are commonly used. Typical methods for producing metal particles include a method of reducing metal salts or oxides, and a method of evaporating metals. However, the manufacturing cost is high, and the degree of freedom in selecting the two magnetic properties is low.

Since the advent of magnetic disks, high-density magnetic recording technology has further developed and research is being conducted at numerous research institutions.

Regarding these, see 2, for example, Journal of the Japanese Society of Applied Magnetics, Vol.
, 3 + 2 1982, or Journal of the Institute of Electronics and Communication Engineers V
As is clear from the 63+N4 April 1980, advances in high-density magnetic recording technology are evident in the development of recording media.

It can be said that a wide variety of technologies have been accumulated, including magnetic heads, positioning systems, and one mechanism for recording and reproducing systems.

To increase the density, there is a method of recording and reproducing in the longitudinal direction of the recording medium (hereinafter referred to as horizontal magnetic recording).

Methods that perform perpendicular magnetic recording to the medium (hereinafter referred to as perpendicular magnetic recording) are competing with each other.

In such high-density magnetic recording, magnetism.

Recording media technology, along with magnetic henode technology, plays a large role.

For high-density magnetic media, horizontal recording is discussed in the above-mentioned Journal of the Institute of Electronics and Communication Engineers (Vol. 63.
As shown in p. 329~), it is desirable to increase the coercive force I (c) of the medium, increase the squareness ratio, and reduce the product tXBr when the residual magnetic flux density Br and the medium thickness t are On the other hand, in perpendicular magnetization, the saturation magnetization Ms of the medium is high, and a high coercive force Hc (contrary to horizontal magnetization, necessary on the low density side) is required to maintain residual magnetization.

It becomes a perpendicular magnetization film.

Hk > 47rMs or Ku>2πMs −(
1) However, the conditions of Hk anisotropic magnetic field Ku crystalline anisotropy constant are required, and for this purpose Ms must be made low, contrary to the above.

In addition, these magnetic media have only the characteristics of the medium <1 For example, the Institute of Electronics and Communication Engineers study group material MR82-15 (
September 14, 1982) or the same research material MR82-
19 (August 11, 1982), it is necessary to consider the characteristics of the magnetic head used for recording and reproduction.

In this way, the selection of magnetic media depends on the recording method.

Alternatively, it is necessary to select a magnetic recording medium according to the characteristics of the recording/reproducing magnetic head.

The present invention uses fine particles of alnico magnet alloy having high residual magnetization as metal magnetic powder coated on a non-magnetic paste in a magnetic recording medium.

Alnico magnet alloy powders having two different magnetic properties can be easily produced by combining one composition and aging conditions, and magnetic powders suitable for various magnetic tapes can be provided at low cost. Alnico magnets are alloys with high squareness and small temperature changes in residual magnetization. Therefore, according to the present invention, it is possible to easily obtain high-performance magnetic tapes with characteristics corresponding to nine types of recording systems and magnetic heads at low cost.

An embodiment of the present invention will be described below.

Example 1゜CO 24% y Ni 14%, AA 8%, Cu
After high-frequency vacuum melting so that the remaining Fe was 3%, the ingot was solution-treated at 1260°C for 1 hour, and about 2DOOKO
The specimens were heat treated in a magnetic field of e from 900°C to 800°C at a cooling rate of 1°C/sec, and aged at 600°C for 20 hours. This alloy was coarsely pulverized to a particle size of approximately 50 μm, and its magnetic properties were measured and found to be Br 13.5KG and He 7500e.

This powder was wet-pulverized to 0.2 μm using a ball mill.

This powder was dispersed in a binder so that the filling rate was 60% in a polyester film and oriented in a magnetic field to prepare a magnetic tape. When this magnetic tape was measured, it was found that it had a residual magnetization of 4000 G, a coercive cuff of 000e, high squareness, and a high-performance magnetic tape that was excellent in temperature changes.

Example 2゜ Same as Example 1, 38% Co, 14% Ni.

At 7.5%, Cu 3%, Ti 8%, balance Fe.

Even solution treatment was performed. After that, in a 2000KOe magnetic field.

Heat treated in a magnetic field for 10 minutes with aop'c at 650°C.
Aging treatment was performed at 550° C. for 6 hours and at 550° C. for 10 hours.

When this alloy was coarsely ground to a particle size of approximately 60 μm and its magnetic properties were measured, it was found that Br 7400G, He 21000
It was e. This powder was ground to 0.2 μm using a ball mill.

A magnetic tape was prepared using this powder in the same manner as in Example 1. I measured this magnetic tape.

Residual magnetization 2150G, good squareness of Hc2000Qe.

A high-performance magnetic tape characterized by high coercive force was obtained.

By heat-treating the crushed powder at 400-900℃,
Improves magnetic properties.

Claims (1)

[Claims] 1. As magnetic particles coated on a non-magnetic base. A magnetic recording medium characterized in that it uses magnetic alloy fine particles containing Al, Ni, and Cof as main components.