JPH0512766B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to magnetic recording media.

Magnetic recording media, such as magnetic tapes, magnetic disks, and magnetic sheets, are made by coating a non-magnetic support such as a polyester film with a magnetic paint in which magnetic powder is dispersed in a resin binder. Because it is run in contact for recording and reproducing, it is subject to a large amount of wear. For this reason, various measures have been taken in the past, such as improving the strength of the coating film, improving lubricity, and forming a protective coating. Among these, lubricants that are dispersed in the magnetic coating or applied to the surface have a high lubricating effect, and are therefore widely used. In particular, higher fatty acids, liquid paraffin, and the like are used as being relatively effective. However, as can be seen from the comparative examples described later, sufficient durability is not obtained even with these lubricants.

Therefore, an object of the present invention is to provide a magnetic recording medium in which the wear resistance of the magnetic layer is improved and the durability is improved.

In the present invention, oleyl oleate, which is an ester of an unsaturated fatty acid and an unsaturated higher alcohol, is dispersed in the magnetic layer or treated on the surface, and its lubricating effect provides significant durability that could not be expected with conventional lubricants. This results in an improvement in

In carrying out the present invention, oleyl oleate is dissolved in a solvent such as n-hexane, and this solution is applied or sprayed onto a previously formed magnetic layer, or the magnetic layer is immersed in this solution.

In case of surface treatment, the amount of oleyl oleate should be used in the range from 0.01 to 1.0 g/m ² . If this amount is less than 0.01 g/m ² , the effect will not be sufficient, and if it exceeds 1.0 g/m ² , the surface of the magnetic layer will become sticky and dirt will easily adhere to it, which is undesirable.

Examples of the present invention will be described in detail below.

Example 1 Part by weight γ-Fe ₂ O ₃ magnetic powder 100 Vinyl chloride-vinyl acetate copolymer 22 (VAGH manufactured by UCC, USA) Polyurethane resin 14 (Nituporan 2304 manufactured by Nippon Polyurethane Co., Ltd.) Polyisocyanate 6 (Coronate manufactured by Nippon Polyurethane Co., Ltd.) L) Carbon black 10 Abrasive 5 Methyl ethyl ketone 150 Toluene 150 The above composition was thoroughly kneaded and dispersed using a pole mill to prepare a magnetic paint, and this was applied onto a polyester base film to a dry thickness of 2.5 μm. After drying, calendering was performed to form a magnetic layer. A lubricant solution consisting of 3 parts by weight of oleyl oleate and 100 parts by weight of normal hexane is applied to the surface of the obtained magnetic layer at a concentration of 0.01 to 1.3 g/m ² , dried, and punched into a disk shape to form a magnetic disk. It was created.

Comparative Example 1 For comparison, a magnetic disk was prepared by punching out a magnetic disk having a magnetic layer that was not surface-treated with oleyl oleate in Example 1.

Comparative Example 2 A magnetic disk was prepared according to Example 1, except that oleic acid was used instead of oleyl oleate.

Comparative Example 3 A magnetic disk was prepared according to the example except that liquid paraffin was used instead of oleyl oleate.

The magnetic disks obtained in Examples and Comparative Examples were inserted into jackets and continuously reproduced at a head pressure of 150 g/cm ² , and the time until the output reached 80% of the initial level was measured.

FIG. 1 shows the measurement results for the surface-treated magnetic disk of Example 1. When the surface concentration of oleyl oleate was 0.01 g/ ^m2 , the durability was about 400 hours, and when the surface concentration of oleyl oleate was 0.01 g/m2, the durability was about 400 ^hours . Durability is over 500 hours. Even at higher surface concentrations, the duration was 500 hours or more. Note that the measurement was stopped after a little over 500 hours, so the actual durability is better than that shown in Figure 1. On the other hand, the same figure also shows the stickiness of the magnetic disk surface. As can be seen from the figure, the surface concentration of oleyl oleate is 1.0 g/m ²
It was found that the stickiness increases as the size increases. In the figure, ◯ indicates no stickiness, △ indicates slight stickiness, and × indicates a large amount of stickiness.

Figure 2 shows the measurement results for the kneading and dispersion type magnetic disk of Example 2. When the amount of oleyl oleate added was 5wt%, the durability was about 350 hours, and when the amount of oleyl oleate added was 10wt%, it was more than 500 hours. . When the amount added exceeds about 40%, durability begins to decrease, and the
It decreased to about 400 hours at 50wt%.

On the other hand, when the durability of Comparative Examples 1, 2, and 3 was measured, the durability was about 50 hours, about 200 hours, and about 150 hours, respectively.
It was time.

From these results, it was revealed that the magnetic layer having the oleyl oleate of the present invention coated on the surface had extremely excellent durability. It will be apparent to those skilled in the art that many variations are possible within the scope of the invention. For example, other resins may be used as the binder resin, or γ-
Not only Fe ₂ O ₃ but also cobalt-coated γ-Fe ₂ O ₃ , metal magnetic powder, etc. can be used.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the durability and stickiness of the magnetic disk according to Example 1 and the surface concentration of oleyl oleate.

Claims (1)

[Claims] 1. In a magnetic recording medium having a magnetic layer formed by dispersing magnetic powder in a resin binder, oleyl oleate is present on the surface of the magnetic layer at a surface concentration of 0.01 to 0.01.
A magnetic disk type magnetic recording medium characterized in that the adhesive is attached at a density of 1.0 g/m ² .