JPH03219418A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain such a medium having high durability and particularly suitable for high-density medium which realizes highspeed transfer with high relative rate by incorporating tetrapod-like whiskers into a magnetic layer of the magnetic recording medium comprising a supporting body and the magnetic layer formed thereon. CONSTITUTION:Since tetrapod-like whiskers have higher three-dimensional strength compared to rod whiskers, a small amt. of tetrapod whiskers added to a magnetic layer give enough durability to the layer. The particle size of the tetrapod whisker particles to be added into the magnetic layer is preferably 10 - 80% of the film thickness. If the size is <10% of the thickness, mechanical strength of the layer can not be obtained, while with >80% particle size, the surface property becomes poor to lose traveling property. On adding tetrapod whiskers into the magnetic layer, the whiskers are first subjected to surface treatment with various kinds of surfactant and then added to the magnetic coating material. Thereby, the whiskers can be dispersed uniformly in the coating material to give better surface and higher durability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic recording medium, and particularly to a magnetic recording medium having high durability.

(Prior Art) In recent years, with the spread of personal word processors and home videos, many magnetic recording media such as floppy disks and video tapes have come on the market.

What is strongly required of such magnetic recording media is:
These include larger storage capacity and faster transfer speeds.

There are two ways to increase the recording capacity: increasing the recording density in the track width direction and increasing the recording density in the track length direction. Progress is being made in increasing recording density.

Furthermore, in order to enable high-speed transfer, attempts have been made to improve the stepping motor and the like to reduce the seek time of the magnetic head, as well as to increase the relative speed between the magnetic head and the magnetic recording medium.

(Problems to be Solved by the Invention) However, increasing the relative speed between the magnetic recording medium and the magnetic head requires the magnetic recording medium to have greater durability than ever before. For this reason, it has become essential to improve the durability of magnetic recording media as the transfer speed of magnetic recording media increases.

It has been known to mix large particle size carbon or the like in order to improve the durability of magnetic recording media. However, in order to increase the recording density, it is necessary to increase the packing density of the magnetic powder, and it is not preferable to increase the amount of carbon or the like added.

Therefore, for example, Japanese Patent Application Laid-Open No. 63-164521 discloses that the durability of a magnetic disk can be improved by adding whiskers to the magnetic disk.

However, if a large amount of whiskers or the like is included in the magnetic recording layer in order to improve the durability of the magnetic recording medium more than before, there is a problem that sufficient reproduction output cannot be obtained.

The present invention was made in view of the above problems, and an object thereof is to provide a magnetic recording medium that has high durability and good electromagnetic conversion characteristics, and is capable of large-capacity and high-speed transfer.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a magnetic recording medium comprising a magnetic layer formed on a support, the magnetic layer containing tetrapot-like whiskers. It is characterized by

(Function) As a result of various studies to solve the above-mentioned problems, the present inventors found that high durability can be obtained by including whiskers having a tetrapod-like structure in the magnetic layer. It started.

These tetrapot-shaped whiskers have higher three-dimensional strength than conventionally known rod-shaped whiskers, so even if only a small amount is added to the magnetic layer, sufficient durability can be ensured. It becomes possible to do so. For this reason, sufficient durability can be obtained even if the amount added to the magnetic layer is significantly reduced compared to conventional methods, so it is necessary to ensure excellent electromagnetic conversion characteristics by making the packing density of magnetic powder sufficiently high. I can do it.

Examples of the magnetic powder used in the present invention include γ-Fe
A variety of materials are used, including O powder, Co-containing -Fe203 powder, etc., plate-shaped powders such as strontium ferrite powder, barium ferrite powder, and metals such as Co, Fe, and Ni, or alloy powders thereof. be done.

Examples of binders include vinyl chloride-vinylacetate copolymer, vinyl chloride-vinylidene acetate copolymer, acrylic acid ester-acrylonitrile copolymer, cellulose derivative, and polyurethane resin.

Various materials such as polyester resins can be used.

Furthermore, a lubricant such as a higher fatty acid or a higher fatty acid ester may be added to the magnetic layer, and aluminum oxide, chromium oxide, or the like may be used as a reinforcing agent in combination with the tetrapod whiskers.

The particle size of the tetrapod whiskers added to the magnetic layer depends on the thickness of the magnetic layer, and is preferably 10% to 80% of the thickness. If the particle size of the tetrapod-shaped whiskers is less than 10% of the film thickness, sufficient durability and mechanical strength cannot be ensured, and if the particle size is greater than 80%, each layer This deteriorates surface properties and impairs running properties.

In addition, when adding tetrapod whiskers to the magnetic layer, surface treatment is performed using various surfactants such as silane coupling agents, aluminum coupling agents, titanate coupling agents, and organic phosphoric acid coupling agents. It may be added to the paint after application. By performing surface treatment using a surface treatment agent in this manner, it is possible to uniformly disperse the particles in the paint, thereby ensuring better surface properties. Therefore, the coefficient of friction between the magnetic recording medium surface and the magnetic head can be reduced, and durability can be further improved.

(Example) EXAMPLES Next, the present invention will be specifically explained using Examples.

[Example 1] (Magnetic powder) Ba-ferrite magnetic powder 100 parts by weight (particle size 0.0
5 microns, plate ratio 3.3) (binder) Nitrocellulose 8 parts by weight Polyurethane 8 parts by weight (dispersant) Lecithin 1 part by weight Phosphate ester 4 parts by weight (reinforcing agent) α-Alumina 5 parts by weight Conductive carbon 2 parts by weight large particle size carbon
A magnetic paint consisting of 3 parts by weight whiskers 3 parts by weight (average particle size 2 microns) (lubricating agent) 5 parts by weight stearic acid (solvent) MEK/cyclohexanone 200 parts by weight was prepared, and this was coated with a 75 micron thick polyester. It was coated onto a base film to a thickness of 3 microns using a reverse coater, dried and cured to produce an original film, which was punched out into a disk shape and rotatably housed in a case to form a disk cartridge.

[Comparative Example] In the above example, a disk cartridge was manufactured using a paint composition that did not contain whiskers.

The disk cartridges obtained in the above Examples and Comparative Examples were installed in a disk drive device, and a durability test was conducted under cyclic environmental conditions.

At this time, the rotation speed of the disk cartridge was 80
The rotation speed was 1500 rpm compared to the Orpm, and the cycle environment was 53°C 50% for 8 hours with an environment change time of 4 hours, and 5°C 10% for 8 hours and an environment change time of 4 hours.

As a result, the comparative example showed durability of 1 million passes, while the disk cartridge of the example showed high durability of 5 million passes. Furthermore, in this example, since tetrapot-shaped whiskers having a desired particle size were added to the magnetic layer, a magnetic recording medium with excellent surface properties could be obtained.

As is clear from these results, even by adding a small amount of tetrapod whiskers to the magnetic layer, the durability of the disk cartridge can be greatly improved, and the output is also almost negligible compared to the comparative example. There was no decline.

In the above-mentioned embodiment, a tetrapod-shaped watermelon
In addition, for the purpose of improving durability, 3 parts by weight of large particle size carbon was added to form a magnetic recording medium, but sufficient durability could be obtained even if the large particle size carbon was omitted.

[Effects of the Invention] As detailed above, according to the present invention, a highly durable magnetic recording medium can be obtained without impairing electromagnetic conversion characteristics. The magnetic recording medium of the present invention is especially suitable as a high-density recording medium capable of high-speed transfer with a high relative speed to a magnetic head.

Claims (1)

[Claims] A magnetic recording medium comprising a magnetic layer formed on a support, characterized in that the magnetic layer contains tetrapod-shaped whiskers.