JPS59229745A - Manufacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To reduce noise and to improve the mechanical strength by kneading a binder resin with a film reinforcing agent and thinner by means of alumina balls, adding magnetic powder, and carrying out kneading again by means of plastic balls to prepare a magnetic coating material. CONSTITUTION:When a coating material prepd. by kneading by means of alumina balls is used, superior mechanical strength is provided, yet an increase in noise and a reduction in the degree of orientation are inevitable. In case of a coating material prepd. by kneading by means of plastic balls, sufficient magnetic recording characteristics are shown when an alumina reinforcing agent is not added. The magnetic recording characteristics are, however, deteriorated by adding only half of the prescribed amount of the reinforcing agent. The necessary components except gamma-Fe2O3 are well kneaded by means of alumina balls, gamma-Fe2O3 is added, and kneading is carried out again by means of plastic balls. By this method, uniform dispersion is attained while minimizing the breaking of gamma-Fe2O3.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium with excellent mechanical strength and low noise.

(b) Background of the technology A magnetic disk uses a non-magnetic metal plate, such as an aluminum alloy plate, as a substrate with a thickness of approximately 2 mm, and a magnetic recording medium is deposited on this using a spin code method, vacuum evaporation method, plating method, etc. It is formed as a thin film.

That is, the spin code method is mainly used for those using oxides such as magnetic iron oxide powder (r-Fe103 hereinafter), while the spin code method is mainly used for those using oxides such as magnetic iron oxide powder (r-Fe103), while
-Co-P), nickel-cobalt (Nt-Co)s
``Vacuum deposition method is used for those using magnetic alloy films such as Paltochrome (Co-Cr).

Thin films are being made using sputtering methods, plating methods, and the like.

The present invention relates to a method for manufacturing a magnetic recording medium that contains r-FetOs as a main component and thins the magnetic recording medium by spin coating.

(c) Prior Art and Problems A necessary condition for a magnetic recording medium is that it not only has excellent magnetic properties, but also has a sufficient mechanical strength.

For example, when a magnetic disk is rotating at high speed, a magnetic head that writes and reads information on a magnetic disk is suspended 0.2 to 0.5 [μm] above the disk surface due to levitation force, and therefore Although there should be no contact, if there is dust or recording medium powder attached to the magnetic head, head clarity (ie, the magnetic head will fall) will occur, and in devices with a contact start/stop configuration, the magnetic head may drop when the magnetic disk starts rotating. Since they are in contact with each other, friction is inevitable and there is also an impact caused by the jumping of the magnetic head.

In this case, since a magnetic film made only of r-FelOs suffers from large wear, it is necessary to strengthen the strength. Generally, non-magnetic particles such as alumina (α-At20.) fine particles are added to reinforce the mechanical strength of the coating film. are doing.

However, it is known that if the degree of dispersion of the added alumina powder is non-uniform or if there is a large amount of powder with a particle size exceeding 1 [μm], this may cause an increase in noise. So, the manufacturing method for magnetic paint is magnetic powder.

Raw materials consisting of a binder resin, a reinforcing agent, and a solvent are sufficiently kneaded using a ball mill to uniformly disperse them to form a paint.

There are two types of kneading methods: one uses alumina balls and the other uses plastic balls such as nylon or Teflon.

The characteristics of both methods are that when the former method is used, cross-talk occurs sufficiently, but alumina abrasion powder is generated from the collision of alumina particles with each other, and since coarse particles are included, noise increases and the alumina ball needle-shaped magnetic powder (
r-FetOs) is broken, deteriorating the magnetic recording characteristics.Also, in the case of the latter method, the crosstalk occurs slowly, so there is no breakage of the magnetic powder, but the dispersion of the hard alumina powder is poor. Even if it is sufficient, it causes bias, and although the magnetic recording characteristics are good, there is a problem that noise becomes high.

(d) Object of the Invention The object of the present invention is to provide a method for obtaining a magnetic recording medium with low noise and excellent mechanical strength.

(e) Structure of the Invention The purpose of the present invention is to divide the mixing of magnetic paint into two stages. First, the binder resin, coating reinforcing agent, and sinker are kneaded using alumina balls, and then the alumina balls are replaced with plastic balls and the magnetic paint is mixed. This can be achieved by adding powder and kneading it again to form a paint.

Example of the Invention The present invention shows that when alumina balls are used as a cross-wire method for magnetic paint, the dispersibility is good, but there are problems with noise and magnetic properties, while when plastic poles are used, there are problems with dispersion. Table 1 shows the numerical values of the problems in which both methods are used.

In Table 1, the noise is the value in the i 0 (MHz) band, and the degree of orientation is expressed by the residual magnetization value relative to the saturation magnetization value in the hysteretic magnetization loop. In other words, the higher the degree of orientation, the better the magnetic recording properties of the medium.

As shown in Table 1, when a paint using alumina balls is used, the mechanical strength is excellent, but an increase in noise and a decrease in the degree of orientation are unavoidable. On the other hand, in the case of a plastic ball kneaded paint, sufficient magnetic recording properties are exhibited when no alumina reinforcing agent is added, but it can be seen that even when only half of the prescribed amount of alumina reinforcing agent is added, the magnetic recording properties are degraded.

In the present invention, the component composition excluding r-Fe20m is sufficiently kneaded using alumina balls, and then r-Fe2Og
By Kokichi, who mixes wires with a plastic ball by adding
- Uniform dispersion is achieved while minimizing breakage of FetOs.

The present invention will be described in detail with reference to Examples below.

Table 2 In Table 2, the materials except for the magnetic powder were put into a ball mill and kneaded for 24 hours using alumina balls, then the alumina balls were replaced with nylon balls of the same diameter, and then kneaded together for 72 hours to create a magnetic A paint was prepared.

Table 3 shows the characteristics of magnetic recording media formed using such magnetic paints, and for reference, shows the characteristics of a paint with the same composition but mixed with only nylon balls (Comparative Example 1) and one using only alumina balls. The kneaded paint (Comparative Example 2) is also shown.

In the preparation of Comparative Example 2, alumina was removed from the component composition shown in Table 2, and alumina was kneaded according to the wear amount of the alumina balls until it reached 1.5 parts by weight.

Table 3 From the results shown in Table 3, the magnetic recording medium obtained by the method of the present invention has a better dispersion state than those obtained by other methods, and therefore has less noise, better orientation, and superior mechanical strength. It can be seen that

(b)) Effects of the invention The present invention combines the advantages of crosstalk using alumina balls and crosstalk using plastic balls, and by implementing the invention, a magnetic recording medium with excellent magnetic recording characteristics and mechanical strength can be obtained. Can be done.

126'.

Claims (1)

[Claims] A magnetic film, which is coated on a non-magnetic substrate and serves as a magnetic recording medium, with the main magnetic powder as the j component, is prepared by first adding a solvent to a binder resin and a reinforcing agent and kneading them using alumina balls. A method for manufacturing a magnetic recording medium, characterized in that the magnetic recording medium is formed using a magnetic paint obtained by adding magnetic powder to the mixed wire material, replacing the alumina balls with plastic balls, and kneading the mixture.