JPS58164025A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance the wear resistance of a magnetic layer by adding an unsatd. fatty acid ester to the layer. CONSTITUTION:To a magnetic layer is added an oleic ester, an elaidic ester, a linolic ester, a linolenic ester or other unsatd. fatty acid ester such as n-butyl oleate or oleyl oleate by 0.1-20wt% of the amount of magnetic powder in the magnetic layer.

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.

Generally speaking, magnetic recording media, which 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, are used to prevent magnetic heads and discs during recording and reproduction. Because of the intense sliding contact, the magnetic layer is likely to be abraded, so a magnetic layer that is less abrasive and has excellent durability is required.

For this reason, various lubricants are mixed into the magnetic layer as a way to improve the wear resistance of the magnetic layer.
For example, a magnetic layer containing stearic acid ester has been proposed.

However, although the abrasion resistance is certainly improved by incorporating stearate, it is not sufficient; in particular, stearate ester is easily volatile and has a chain point where it cannot maintain a good lubricating effect 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 incorporating an unsaturated fatty acid ester into the magnetic layer, and the effect can be maintained for a long period of time. They discovered this and came up with this invention.

The unsaturated fatty acid ester used in this invention has low volatility because it has an unsaturated double bond, and also has excellent lubricating ability, and when contained in the magnetic layer, this excellent lubricating effect is exhibited. The wear resistance of the magnetic layer is improved and the effect is maintained for a long period of time.

Such an effect is exhibited by containing 0.1% or more of unsaturated fatty acid ester in the magnetic layer based on the magnetic powder, and the effect becomes more pronounced as the content increases. , the content is 20 for magnetic powder.
If the magnetic powder exceeds % (C), it will bleed out onto the surface of the magnetic layer, contaminating the magnetic head and reducing the output.
It is preferable that the content in the magnetic layer be within the range of 0.1 to 20% by weight.

Such unsaturated fatty acid esters include oleic acid ester, elaidic acid ester, linoleic acid ester,
Linoleic acid esters are preferably used,
Specific examples include n-butyl oleate, oleyl oleate, and the like.

In order to incorporate the unsaturated fatty acid ester into the magnetic layer, it can be dissolved in a suitable solvent such as n-hexane, and the solution obtained by dissolution can be coated or sprayed on a pre-formed magnetic layer, or This can be done by immersing the reverse VC magnetic layer in the above solution, and this can be done by immersing the reverse VC magnetic layer in the above solution. It may also be incorporated by kneading it with a binder resin to form a magnetic layer.

Next, embodiments of the invention will be described.

Example I Co-containing -1-e20Jm powder 270 parts V
AGH (manufactured by U, C, C, USA, salt 8o
　vinyl chloride-vinyl acetate-vinyl alcohol copolymer) N], 432 J (manufactured by Nippon Zeon Co., Ltd., 15
〃Acrylonitrile-butadiene copolymer) Coronate Shiku Nippon Polyurethane I Q -tt
Trifunctional low molecular weight isocyanate compound (manufactured by T Gyo Co., Ltd.) N5-500 (manufactured by Asahi Carbon Co., Ltd. 34 〃Carbon blank) α-Fe205 powder 11 〃Methyl isobutyl ketone 420 〃Toluene
42o This composition is mixed and dispersed in a ball mill to prepare a magnetic paint, and the magnetic paint is coated with a thickness of 75 mm.
A magnetic layer was formed by coating and drying a polyester film of 3 μm on both sides to a dry thickness of 3 μm. Next, this was immersed for a short time in an impregnating solution consisting of 50 parts by weight of n-butyl oleate and 21,000 parts by weight of n-hexane, dried, and punched out into a disk shape to produce a magnetic disk.

Example 2 In the composition of the magnetic paint in Example 1, the amount of VAGH used was changed from 80 parts by weight to 40 parts by weight, and the amount of Coronate L was changed from 10 parts by weight to 20 parts by weight, and N1432J was omitted. New bandex'l゛-
A magnetic disk was produced in the same manner as in Example 1, except that 40 times 5201 (manufactured by Dainippon Ink & Chemicals, Inc., urethane elastomer) was added to the wound area.

Example 3 A magnetic disk was produced in the same manner as in Example 1 except that the same amount of oleyl oleate was used in place of n-butyl oleate in the composition of the impregnating solution #1.

Comparative Example 1 A magnetic disk was produced in the same manner as in Example 1, except that the same amount of n-butyl stearate was used in place of n-butyl oleate in the composition of the impregnating solution in Example.

Comparative Example 2 A magnetic disk was produced in the same manner as in Example 2, except that in the composition of the impregnating solution in Example 2, the same amount of n-butyl stearate was used in place of -0-butyl oleate.

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 25 g/c+J. Circumferential speed lom/s
The running time until the playback output reached 50% of the initial output was measured while making sliding contact with the ee. Further, in order to examine the lubrication-sustaining effect, the magnetic disk was left in an environment at 60'C for 30 days, and the amount of lubricant volatilized was measured and expressed as a percentage of the initial impregnated amount.

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 3) have longer running times and have less sustained lubrication effect than conventional magnetic disks (Comparative Examples 1 and 2). This clearly shows that the magnetic recording medium obtained by the present invention has excellent durability and its effects are maintained over a long period of time.

Patent applicant: Hitachi Maxell, Ltd. 153-

Claims (1)

[Claims] ■Magnetic recording medium having a magnetic layer containing unsaturated fatty acid ester