JPH03214418A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain high durability in a range from low temp., low humidity to high temp., high humidity by adding a lubricant and a proper amt. of humectant into a magnetic layer. CONSTITUTION:A magnetic layer containing higher fatty acid and higher fatty acid ester as a lubricant is formed on a supporting body. This magnetic layer contains a humectant by >=10 and <=50 pts.wt. to 100 pts.wt. of the lubricant. By adding the humectant, humidity in the recording medium can be controlled. If the add amt. is <10 pts.wt. of the lubricant, the effect of keeping moisture can not be enough obtained, while with over 50 pts.wt., sucking of a head to the recording medium at high humidity is caused.

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, personal computers, 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 increased storage capacity and faster data transfer.

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 to increase recording density in the width direction.

As for the transfer speed, attempts have been made to achieve high-speed transfer by increasing the relative speed between the magnetic head and the magnetic recording medium.

(Problem to be solved by the invention! Ili) However, increasing the relative speed between the magnetic recording medium and the magnetic head for recording/reproduction places a large burden on the magnetic recording medium.

For this reason, improving the durability of magnetic recording media has become an issue.

In order to improve the durability of magnetic recording media, myristic acid, stearic acid, palmitic acid,
By blending lubricants such as higher fatty acids such as oleic acid or fatty acid esters such as butyl stearate and butyl valmitate, good lubricity is maintained between the magnetic recording medium and the magnetic head, and durability is improved. Attempts are being made to improve it.

However, at present, it has not been possible to ensure good lubricity between the magnetic recording medium and the magnetic head over a wide range of temperatures from low temperature and low humidity to high temperature and high humidity. It has been difficult to obtain sufficient durability in magnetic recording media for high-density recording with high relative speeds.

The present invention was made in view of the above-mentioned problems, and it is an object of the present invention to provide a magnetic recording medium that has high durability in a wide range of temperatures from low temperature and low humidity to high temperature and high humidity.

[Structure of the Invention] (Means for Solving the Problems) The magnetic recording medium of the present invention includes a magnetic layer containing a higher fatty acid and a higher fatty acid ester as a lubricant formed on a support, It is characterized in that the magnetic layer contains 10 parts by weight or more and 50 parts by weight or less of a humectant based on 100 parts by weight of the lubricant.

(Function) Conventionally, focusing on reducing the friction between the magnetic recording medium and the magnetic head, efforts have been made to activate the surface of the magnetic recording medium with a lubricant, polish the surface of the magnetic recording medium, etc., and improve the durability of the magnetic recording medium. Attempts have been made to improve.

In particular, it is possible to significantly improve the durability of a magnetic recording medium by adding a lubricant, but this method is highly dependent on the environment and causes large variations in durability.

Even when higher fatty acids and fatty acid esters are used together as a lubricant that works well from low temperature and low humidity to high temperature and high humidity, although the coefficient of friction temporarily decreases under low humidity conditions, it does not prevent long-term sliding. On the other hand, the friction coefficient gradually increases. On the other hand, under humid conditions, the balance between the lubricant and humidity causes a sudden increase in friction from a certain area, causing an adsorption phenomenon.

Therefore, the present inventors have discovered that by adding a lubricant and an appropriate amount of humectant, it is possible to always ensure a magnetic recording medium with good surface properties without being affected by temperature and humidity.

By adding a humectant in this manner, the humidity in the magnetic recording medium was controlled and the magnetic recording medium always had a good surface condition.

Furthermore, from various experiments, the present inventors found that lubricant 100! J.I.
It has been found that particularly good results can be obtained by adding a humectant in an amount of 10 parts by weight or more and 50 parts by weight or less. If the amount of humectant added is less than 10 parts by weight relative to the lubricant, it is difficult to obtain a sufficient moisturizing effect, and if it is more than 50 parts by weight, the magnetic recording medium and magnetic head may be damaged under high humidity. An adsorption phenomenon occurs during this time.

Various lubricants can be used in the present invention, but by using a higher fatty acid and a higher fatty acid ester in combination, it can work well from relatively low temperature and low humidity to high temperature and high humidity. Examples of higher fatty acids include oleic acid, linoleic acid, stearic acid, myristic acid, etc., and these esters can be used as higher fatty acid esters.

The humectant used in the present invention includes squalane (C3
oH62). Squalene (C3oH5o) is applicable, but squalane (C3oH62) is particularly preferred.

Examples of the magnetic powder used in the present invention include γFe
Acicular powder such as 20a powder, Co-containing 7Fe20a powder, plate-like powder such as strontium ferrite powder, barium ferrite powder, Fe-Co, Fe-Co
Various materials such as alloy powder magnetic materials such as -Ni are used.

In addition, as a binder, vinyl chloride-vinylidene acetate copolymer, vinyl chloride-vinylidene acetate copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, methacrylic ester-acrylic nitrile copolymer A variety of materials can be used, including polymers, cellulose derivatives, polyurethane resins, and polyester resins.

(Example) 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 resin 6 parts by weight Polyurethane resin 12 parts by weight (dispersant) Lentin 1 part by weight Phosphate ester 1 part (reinforcing agent) α alumina 5 parts by weight carbon
5 parts by weight (lubricant) Butyl stearate 2 parts by weight Oleic acid 3 parts by weight (solvent) MEK/cyclohexanone 220 parts by weight (humectant) Swaran 0.5 parts by weight (10 parts by weight
0 parts by weight) was prepared, 5 parts by weight of a trifunctional low molecular weight isocyanate compound was added, and this was coated on a polyester base film with a thickness of 75 microns in a film thickness of 3 microns. Coated. Then, it was dried and cured to produce an original fabric, punched into a disk shape, and rotatably housed in a case to form a disk cartridge.

[Example 2] A magnetic disk was produced in the same manner as in Example 1 except that squalane was used in an amount of 1.5 parts by weight (30 parts by weight per 100 parts by weight of the lubricant).

[Example 3] A magnetic disk was produced in the same manner as in Example 1 except that squalane was used in an amount of 2.5 parts by weight (50 parts by weight per 100 parts by weight of the lubricant).

[Comparative Example 1] A magnetic disk was produced in the same manner as in Example 1 except that squalane was used in an amount of 5 parts by weight (same part by weight as the lubricant).

[Comparative Example 2] A magnetic disk was produced in the same manner as in Example 1 except that squalane was not added.

[Comparative Example 3] A magnetic disk was produced in the same manner as in Example 1 above, except that oleic acid and butyl oleate were not added.

The disk cartridges obtained in the above Examples and Comparative Examples were installed in a disk drive device, and
), normal temperature and humidity (23℃50%). High temperature and high humidity (60℃90
Durability tests were conducted under three types of conditions:

The rotation speed of the disc cartridge at this time is 300 rpm.
The pad pressure of the magnetic head was set at 40 g/cs2, and measurements were made until the reproduction output reached 80% of the initial output.

Table 1 shows the results of this example and comparative example.

Table 1 As is clear from Table 1, by adjusting the amount of squalane added to 10 parts by weight or more and 50 parts by weight or less per 100 parts by weight of oleic acid and butyl oleate, it is possible to change the temperature from low temperature and low humidity to high temperature and high humidity. It can be seen that good durability can be obtained over a wide range.

Furthermore, since the amount of humectant added is very small overall, there was no reduction in the reproduction output compared to the conventional case.

In this example, squalane was used as a humectant, but other humectants may be used.

[Effects of the Invention] As detailed above, according to the present invention, a magnetic recording medium with high durability can be obtained regardless of the external environment. Therefore, the magnetic recording medium of the present invention is suitable for use in extremely harsh environments, and is most suitable for high-density recording media in which the relative speed between the magnetic recording medium and the magnetic head is faster than that of conventional media.

Claims (1)

[Claims] In a magnetic recording medium in which a magnetic layer containing a higher fatty acid and a higher fatty acid ester as a lubricant is formed on a support, 10 parts by weight or more and 50 parts by weight per 100 parts by weight of the lubricant in the magnetic layer. A magnetic recording medium characterized by containing the following moisturizing agent.