JPS5836412B2 - How to make magnetic paint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a magnetic paint, and more particularly to a method for manufacturing a magnetic paint used in manufacturing a magnetic recording medium that performs magnetic recording and reproduction.

In general, magnetic recording media are manufactured by coating a base material with a magnetic paint consisting of magnetic powder and its binder, and going through a predetermined process.

Incidentally, magnetic paints are manufactured by a known ball mill method, in which a ball made of metal such as steel or stainless steel or a sintered body of oxide such as alumina or zirconia is used as a pole.

However, when magnetic paint is manufactured using such hard balls, the magnetic powder is subjected to large stress due to the collision of the balls during the ball mill, which impairs the magnetic properties of the magnetic powder and deteriorates the magnetic properties of the magnetic recording medium. It was the cause.

Therefore, it is an object of the present invention to provide a ball that eliminates the drawbacks of the conventional ball mill, that is, a new ball that can alleviate the stress that magnetic powder is subjected to during a pole mill, and to use the ball to create a magnetic paint. The object of the present invention is to provide a method for producing a magnetic coating material in a magnetic recording medium obtained by coating a base material with a magnetic coating material, the method of producing the magnetic coating material as a core material. This can also be achieved by a method for manufacturing magnetic paint, which uses a sintered body of metal or oxide and uses balls whose surfaces are coated with resin to form a magnetic paint by a ball milling method.

Hereinafter, the present invention will be explained in detail according to the drawings and examples.

FIG. 1 shows the shape of the pole according to the present invention, where 1 is a core material with a diameter of 11 g, and 2 is an outer grain resin with a diameter of 18 l.

The material used for the core material 1 may be either metal or non-metal as long as it can provide the ball weight described later, but preferably a non-magnetic material.

Further, the outer grain resin 2 may be either thermosetting or thermoplastic as long as it can be molded into a spherical shape.

If the weight of one ball is less than 5 g, the dispersibility of the magnetic powder will be insufficient, and if it exceeds 25 g, the stress applied to the magnetic powder will be too strong and the magnetic properties will be impaired.

Therefore, the weight of one ball is preferably 5 g or more and less than 25 g.

Furthermore, if the size of the pole is less than 10 mm in diameter and 25 mm or more, the dispersibility of the magnetic powder will be insufficient, so it is preferably 10 mm or more in diameter and less than 25 mm.

Next, examples of the present invention will be described in detail.

Example 1 A ball having the shape shown in Fig. 1 and weighing approximately 8 g, using stainless steel as the core material and polyethylene resin as the outer grain resin, and an alumina pole with a diameter of 15 mm were mixed in a weight ratio of 1.
Ball milling was carried out at a ratio of :3 to produce a magnetic paint containing 55% by weight of magnetic powder.

This magnetic paint was coated on an aluminum disk using a spin coating method, and magnetic field orientation was performed.

At this time, the squareness ratio (Br/Bs) of the magnetic coating film is 0.8
38-Differential half-width obtained from the differential curve of the H loop (△
H) became 150 oersteds.

Example 2 When ball milling was performed with the ratio of each pole shown in Example 1 being 1=1 and the same treatment was performed, the squareness ratio of the magnetic coating film was 0.85 and the differential half width was 120 Oe.

Example 3 When the ratio of each ball shown in Example 1 was 1201, that is, a ball mill was performed without the alumina balls and the same treatment was performed, the squareness ratio of the magnetic coating was 0.88 and the differential half width was 100. It became Ørsted.

Example 4 When the alumina balls shown in Examples 1 to 3 were replaced with stainless steel poles and the same treatment was performed, Examples 1 to 3 were obtained.
The same results as in 3 were obtained.

Example 5 The same results as in Example 3 were obtained when the same treatment as in Example 3 was performed except that the core material of the ball was changed to brass.

Example 6 When the magnetic powder content shown in Examples 1 to 3 was changed from 55% (weight ratio) to 75% and the same treatment was performed, Examples 1 to 3 were obtained.
The same results as in Example 3 were obtained.

The results of each of the above examples are shown in FIG.

Example 7 When the outer grain resin of the balls shown in Examples 1 to 3 was changed to nylon resin and the same treatment was performed, the same results as in Examples 1 to 3 were obtained.

Example 8 When the outer grain resin of the balls shown in Examples 1 to 3 was used as tetrafluoroethylene resin and the same treatment was performed, Examples 1 to 3 were obtained.
The same results as in 3 were obtained.

By using a metal or the like as a core material and using a ball whose surface is coated with resin, the magnetic properties of the magnetic paint, or in other words, the magnetic properties of the magnetic recording medium, can be improved. It's thick.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of the ball according to the present invention, and FIG. 2 is a graph showing the squareness ratio and the differential half width when the mixing weight ratio of the pole according to the present invention is changed.

Claims (1)

[Claims] 1. A method for producing a magnetic coating in a magnetic recording medium obtained by coating a base material with a magnetic coating, in which a metal or oxide sinter is used as a core material, and a resin is coated on the surface of the core material. 1. A method for producing a magnetic paint, comprising producing the magnetic paint by a pole mill method using balls.