JPS58164029A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance the wear resistance of a magnetic layer by adding a liq. hydrocarbon and capric acid to the layer optionally together with carbon black. CONSTITUTION:To a magnetic layer are added a liq. hydrocarbon such as liq. paraffin, squalane, squalene, synthetic squalane, synthetic squalene or polymerized oil or alpha-olefin and capric acid in 99:1-50:50 weight ratio. Carbon black having 40mmu average single particle size and 400ml/100g DBP oil absorption may be added furthermore.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium, and an object thereof is to provide a magnetic recording medium with excellent durability.

In general, magnetic recording bodies are made by coating a magnetic paint consisting of magnetic powder, binder resin, organic solvent, and other necessary components on a substrate such as a polyester film, and are used as magnetic heads and pads during recording and reproduction. Because of the delicate sliding contact, the magnetic layer is easily abraded, and a magnetic layer that is less abrasive and has excellent durability is required.

Therefore, as a measure to improve the wear resistance of the magnetic layer, various lubricating agents have been mixed into the magnetic layer.For example, liquid hydrocarbons such as synthetic squalane and liquid paraffin, and liquid carbonized A magnetic layer in which hydrogen and stearic acid are mixed has been proposed.

However, although the abrasion resistance is certainly improved by the addition of these sea bream lubricants, it is not sufficient. In particular, when synthetic squalane is used alone, it easily volatizes and has the disadvantage that a good lubricating effect cannot be maintained for a long period of time.

The inventors conducted various studies in view of the above circumstances, and found that the abrasion resistance of the magnetic layer can be sufficiently improved by containing liquid hydrocarbons and capric acid in the magnetic layer. With hydrocarbon and capric acid, average single particle size is 40m, iz and DBPI & oil amount is 4
It was discovered that the inclusion of carbon black of 00 rnll / 100 jF lowers the friction coefficient of the magnetic layer and further improves the wear resistance of the magnetic layer, leading to the present invention.

The liquid hydrocarbon used in this invention is preferably, for example, liquid paraffin, squalane, squalene, synthetic squalane, virgin squalene, α-olefin polymerized oil, or the like. All of these types of liquid hydrocarbons are expanded hydrogen oils that are liquid at room temperature, and have excellent lubrication ability and improve the wear resistance of the magnetic layer.

In addition, capric acid used in combination with liquid hydrocarbon has a carbon number of 1.
0 saturated fatty acid, has low volatility and excellent long-lasting lubrication effect, and when used in combination with liquid hydrocarbon, this effect is exhibited, further improving the wear resistance of the magnetic layer and reducing wear resistance. is sustained over a long period of time.

The blending ratio of capric acid to liquid hydrocarbon is 99:1 to 5 by weight (liquid hydrocarbon to capric acid).
It is preferable to keep the ratio within the range of 0:50; if the blending ratio of capric acid is too small, sufficient lubrication sustaining effect will not be exhibited, and if it is too large, durability will decrease. In addition, the combined amount of liquid hydrocarbon and capric acid blended in this proportion is 0.1 to 20% of the magnetic powder.
It is preferable to keep the amount within the range of %. If it is too small, the desired effect cannot be obtained, and if it is too large, it may bleed out onto the surface of the magnetic layer, contaminating the magnetic head, and reducing the output.

The carbon black used together with the liquid hydrocarbon and capric acid has an average single particle size of 40rrLμ and D
A carbon black having a BP oil absorption of 400 mfl/100& is preferably used, and specific examples of such carbon black include H5-500 manufactured by Asahi Carbon Co., Ltd., and the like. This type of carbon platter has a lubricating ability, and when contained in the magnetic layer, reduces the coefficient of friction on the surface of the magnetic layer and improves the wear resistance of the magnetic layer. Therefore, when this type of carbon black is used together with a liquid hydrocarbon and capric acid, the wear resistance of the magnetic layer is further improved, and a durable magnetic recording medium can be obtained. The amount used is within the range of 3 to 15% of the magnetic powder +1
If it is too small, the coefficient of friction on the surface of the magnetic layer cannot be sufficiently reduced and the wear resistance cannot be sufficiently improved, and if it is too large, the content of magnetic powder will be relatively reduced and the magnetic properties will be deteriorated. may have an adverse effect on

In order to incorporate liquid hydrocarbons and capric acid into the magnetic layer, they can be dissolved in a suitable solvent such as n-hexane, and the resulting solution can be applied or sprayed onto a previously formed magnetic layer, or vice versa. This may be carried out by immersing the magnetic layer in the above solution, or it may be incorporated by kneading these together with magnetic powder and binder resin to form a magnetic layer. Further, the above-mentioned carbon black is incorporated into the magnetic layer by kneading it with a magnetic powder and a binder resin to form a magnetic layer.

Next, embodiments of the invention will be described.

Example I Co-containing r-Fe, O, magnetic powder 270 parts by weight V
AGH (manufactured by U.S.A., C-C, chloride 80 Vinyl-acetyl vinyl/real alcohol copolymer) N1432J (manufactured by Nippon Zeon Co., Ltd., 15 acrylonitrile-butadiene copolymer) Coronate Japan Polyurethane 10 parts by weight (manufactured by Kogyo Co., Ltd., trifunctional low molecular weight isocyanate compound) H8-500 (manufactured by Asahi Carbon Co., Ltd., 34 〃Carbon black, average single particle size 40rrLμ, DBP oil absorption turtle 400 rrLl/100F) α-Fe203 powder 11 〃Methyl isobutyl ketone 420 Toluene
420 This composition was mixed and dispersed in a ball mill to prepare a magnetic paint, and the magnetic paint was coated in a 75μ thick layer.
A magnetic layer was formed by coating both sides of the polyester film to a dry thickness of 3 μm and drying. Next, this was immersed for a short time in an impregnating solution consisting of 45 parts by weight of synthetic squalane, 5 parts by weight of capric acid, and a 1000-type n-hexane needle, and after drying, it was punched out into a disk shape to produce a magnetic disk.

Example 2 In the composition of the magnetic paint in Example 1, VA G
Change the needle used for H from 80 overlapped part to 40 heavy chain part, and use N1
432J was omitted, and 4 new Bandex T-5201 (manufactured by Dainippon Ink & Chemicals Co., Ltd., urethane elastomer) was added.
A magnetic disk was produced in the same manner as in Example 1, except that 0 parts by weight was added and the amount of Coronae) L used was changed from 10 parts by weight to 20 parts by weight.

Example 3 A magnetic disk was produced in the same manner as in Example 1 except that the same amount of liquid paraffin was used in place of the synthetic squalane in the composition of the impregnating solution in Example 1.

Example 4 In the composition of the magnetic paint in Example 1, N5-50
A magnetic disk was produced in the same manner as in Example 1 except that 0 was omitted.

Comparative Example 1 A magnetic disk was produced in the same manner as in Example 1 except that capric acid was omitted from the composition of the impregnating solution in Example 1.

Comparative Example 2 A magnetic disk was produced in the same manner as in Example 1 except that synthetic squalane was omitted from the composition of the impregnating solution in Example 1.

Comparative Example 3 A magnetic disk was prepared in the same manner as in Example 3 except that the same amount of stearic acid was used instead of capric acid in the composition of the impregnating solution in Example 3.

In order to examine the durability of the magnetic disks obtained in each example and each comparative example, each magnetic disk was inserted into a dirt prevention jacket and loaded into a recording/reproducing device, and the magnetic head was brought into contact with a pad pressure of 251/cm2. peripheral speed 10m
The playback output is 50% of the initial output while sliding at /sec.
The driving time until it becomes fixed, eh.
゛The table below shows the results.

As is clear from the table above, all of the magnetic disks obtained by the present invention (Examples 1 to 4) have longer running times than conventional magnetic disks (Comparative Examples 1 to 3), and therefore, this It can be seen that the magnetic recording medium obtained by the invention has excellent durability.

Patent applicant: Hitachi Maxell, Ltd. Agent Takaoka-Haru

Claims (1)

[Scope of Claims] 1. A magnetic recording medium having a magnetic layer containing a liquid hydrocarbon and capric acid 2. A magnetic recording medium containing a liquid hydrocarbon, capric acid, and an average single particle size of 40 μm and DBP Oil absorption amount is 400m1/100fI
A magnetic recording medium having a magnetic layer containing carbon black.