JPS63152023A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain an excellent electromagnetic conversion characteristic and durability by filling a material essentially consisting of an org. solvent into the spaces between magnetic particles formed perpendicularly on an intra-surface recording medium. CONSTITUTION:After projections 5 are formed by sputtering a polyamide film in Ar, the acicular magnetic particles 6 of Co are formed by sputtering vapor deposition of Co. The acicular magnetic particles 6 fixed perpendicularly on the base film are then securely reinforced by a resin 7 consisting of an org. material and stearing acid or butyl stearate of an org. lubricating agent forms a lubricating layer 8 on the surface of the magnetic layer 9. Namely, the lubricating agent is replenished from the magnetic layer even if said agent is removed by contact with a head; therefore, the durability is greatly improved. Al2O3 particles are kneaded as a polishing agent with the lubricating agent, by which the fine particles thereof are pressed to the head on the surface of the magnetic layer and the exfoliation of the magnetic layer 9 or the chipping thereof is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording medium used as a magnetic tape or a floppy disk, and more particularly to a magnetic recording medium with greatly improved durability and electromagnetic conversion characteristics.

Conventional technology In recent years, in the field of magnetic recording, recording wavelengths have become shorter as recording density has increased, and VH5-VTRs have a minimum wavelength of 1.
．． 2 prn, 8. 0.6μm for w*VTR
- An extremely short wavelength is used. On the other hand, Co-iron oxide tapes with surface roughnesses of approximately 600 mm and metal tapes with surface roughnesses of 200 to 300 mm are used in correspondence with the above-mentioned VTRs.

In general, as the recording wavelength becomes shorter, the surface roughness of magnetic recording media decreases, and considerable technological improvements are required to improve characteristics related to durability (increase in head clogging, dropouts, etc., media destruction). is required.

Furthermore, as shown in FIG. 6, there is a perpendicular recording medium as a medium used in the recording wavelength range of 0.1 to 0.5 μm. An alloy film such as Go-Or is formed by vapor deposition or sputtering on a base film 1 of polyamide, polyimide, polyethylene terephthalate, etc., and a fluorine-based lubricant, polymeric fatty acid, etc. is applied on the alloy film to improve durability. A lubricant layer 3 is provided for the purpose of lubrication. The electromagnetic conversion characteristics of perpendicular recording media have a significantly improved output level in the recording wavelength range of 0.1 to 0.6 μm compared to other longitudinal recording media such as coated tapes.

Problems to be Solved by the Invention However, as the recording wavelength is becoming shorter, for example, if the recording wavelength is 0.5 μm and the thickness of the lubricant layer is 100 people, the loss of the reproduced signal due to the spacing between the bed and the tape is approximately 1.
dB, which naturally places a limit on the thickness of the lubricant layer. When a magnetic head slides over such a thin lubricant layer while making contact with it many times, the lubricant layer provided on the alloy film such as Co-0r is gradually removed by contact with the head, resulting in a large number of It cannot withstand repeated use, and minute defects in the alloy film are enlarged or scraped off and adhere to the head surface, causing head clogging.

In extreme cases, even the head may be damaged.

Moreover, even if the Co-0r film is not destroyed, the Co-0r film may not be destroyed.
The Cr film becomes locally bent due to scratches caused by the sliding movement of the head and tape.

As a result, there was a problem in that the contact between the head and the tape deteriorated, leading to a significant drop in signal level.

On the other hand, in terms of electromagnetic conversion characteristics, the recording wavelength is 0.1 to 0.6 μm.
In the region , the output level is 10 dB or more higher than that of the coated metal tape. However, in the region where the recording wavelength is 1 μm or more, 1. The output level is low compared to the above tapes, and there is sufficient S.
The problem was that /N could not be obtained.

In view of the above problems, the present invention provides a magnetic recording medium with excellent durability and electromagnetic conversion characteristics.

Means for Solving the Problems In order to solve the above problems, the magnetic recording medium of the present invention comprises:
It consists of an organic film formed on the surface of a recording medium for in-plane recording, acicular magnetic particles formed perpendicularly on the surface of the organic film, and an organic material filling the spaces between the acicular magnetic particles.

Function The present invention improves the output level particularly in the long wavelength region and improves the electromagnetic conversion characteristics by creating a two-layer structure for in-plane and perpendicular recording. By filling between the particles, the magnetic layer is protected from the force caused by contact with the head, and its durability is greatly improved.

EXAMPLE A magnetic recording medium according to an example of the present invention will be described below. In FIG. 1A, a polyamide film is sputtered in Ar using an RF sputtering device to form protrusions 6, and then Co is sputter-deposited to form acicular magnetic particles 6 of Co. This is called sample A.

At this time, the length of the magnetic particles was 0.5 μm.

Regarding this, as already explained in Materials P31 to P39 of the 47th Research Meeting of the Japanese Society of Applied Magnetics, the shape of the acicular magnetic particles that will be formed after that depends on the density, width, height, etc. of the protrusions on the film. is determined.

The sample in FIG. 1A has an air pressure of 2×10 −6 Torr.

The film was created while being moved under an Ar pressure of 2×10 −5 Torr.

This sample A has a head-tape relative speed of 3.76.
m/! While repeatedly recording and reproducing a 6 MHz signal using a VTR, changes in the level of the reproduced signal were observed. At this time, the tape length was 20 m, and a ferrite video head was used as the magnetic head.

As a result, a characteristic curve 19 shown in FIG. 2 was obtained.

A characteristic curve 21 shows the relative output of the Co-0r vertical recording medium shown in FIG. As can be seen from the figure,
Although it is better than Co-Cr characteristic curve 21, the output fluctuates after about 60 runs, and after 100 runs, the output decreases by 10 to 20 dB and the tape magnetic layer is damaged, making it impractical. There was a problem.

On the other hand, FIG. 3 shows the electromagnetic conversion characteristics, in which the frequency characteristics of the reproduced output were measured using a ferrite head gap length of 0.23 μm and a head-tape relative speed of 376 m/sec.

The characteristics of the Fe--Ni metal tape (coated tape) are shown by a characteristic curve 26. On the other hand, the Go--Cr vertical tape has a characteristic curve 22, and the above sample A has a characteristic curve 24, indicating that the same characteristics as the Co--Cr vertical tape have been obtained.

However, in the high frequency region (short wavelength region), for example, 066μ
At a recording wavelength of m, it is superior to the metal tape by more than 10 dB, but in the low frequency region (long wavelength region), it is about 6 dB better than the metal tape.
There were problems such as the output level was low in dB and a sufficient S/N ratio could not be obtained.

Next, a coated magnetic layer 12 made of Fe-Ni alloy powder was provided on the polyethylene terephthalate film 13 shown in FIG.
．． A film having the above-mentioned acicular magnetic particles formed on the polyamide film was manufactured by coating the polyamide film to a thickness of 6 μm. This is called sample B.

Next, the coating material kneaded with the composition shown in Table 1 is put into the coating agent tank 26 shown in FIG. 29, and a doctor blade 3o was used to obtain a constant film thickness. The coating thickness at that time is 1 μm from the polyamide film.
The coated film was then pressed down by passing between calender rolls heated to 70 to 80'C, so that it had the same height as the acicular magnetic particles. Next, in order to cure the resin made from the organic material, Sample C was obtained by leaving it in an electric furnace at 70'C for 24 hours.

The composition of the above paint is 1st with 100 parts of acicular magnetic particles.
Shown in the table.

Sample C thus obtained was tested by the above method, and as a result, a characteristic curve of 2° in FIG. 2 was obtained.

It can be seen that the durability is greatly improved compared to characteristic curve 19. This is because the resin 7 made of an organic material for Sample A strongly reinforces the acicular magnetic particles fixed vertically on the base film, and also uses stearic acid, an organic lubricant shown in Table 1. Butyl stearate forms a lubricant layer on the surface of the magnetic layer 9, and even if it is removed by contact with the head, it is replenished from the magnetic layer, so durability is greatly improved. Furthermore, by kneading Al2O2 particles as the abrasive material 9 shown in Table 1, the fine particles of the abrasive material At2o3 come into contact with the head on the surface of the magnetic layer, and serve to prevent the magnetic layer from being peeled off or scraped off. is playing.

In addition to At203, Cr203 and a
-Fe 203. SiO2 and the like are also effective.

On the other hand, regarding the electromagnetic conversion characteristics, characteristic curve 23 in Figure 3
As shown in the figure, Sample C has an approximately 6 dB improvement in output in the low frequency region (long wavelength region), and an improvement in output in the high frequency region (short wavelength region).
It was found that the sample exhibited excellent properties equivalent to those of sample A.

The reason for this is that, as shown in the model diagram in FIG. 6, due to the semicircular magnetic field generated from the head gap 13 formed by the pair of head cores 14, the magnetic layer 9 close to the head is magnetized in the perpendicular direction. A magnetization 16 is formed. on the other hand,
Magnetic layer 12 of the longitudinal recording medium located away from the head
In this case, it is considered that efficient recording and reproducing is performed by forming the magnetization 16 in the horizontal direction.

In the above embodiments, polyurethane and vinyl chloride were used as resins, but nitrolcellulose and other resins, and fatty acids such as oleic acid and syristinic acid are also effective as lubricants.

Furthermore, although a metal tape was used as the in-plane recording medium, other Co-iron oxide or other in-plane recording tapes are also effective.

Effects of the Invention As described above, according to the present invention, by filling the spaces of magnetic particles formed perpendicularly on a longitudinal recording medium with a substance mainly composed of an organic solvent, the electromagnetic conversion characteristics and durability can be significantly improved. An excellent magnetic recording medium can be obtained. Furthermore, by adding an abrasive to the organic solvent,
This has the effect of further preventing the magnetic layer from peeling off or being scraped off.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of the magnetic recording medium of the present invention, FIG. 2 is a characteristic diagram showing the durability of the magnetic recording medium of the present invention, FIG. 3 is a characteristic diagram showing electromagnetic conversion characteristics, and FIG. 6 is a cross-sectional view showing the structure of a coating device for producing the magnetic recording medium of the present invention; FIG. 6 is a cross-sectional view showing the principle of the magnetic recording medium of the present invention; FIG.
The figure is a sectional view showing the structure of a conventional alloy thin film recording medium. DESCRIPTION OF SYMBOLS 1... Base film, 2... Alloy thin film, 3゜8... Lubricating layer, 4, 11...
Polyamide film, 6... Protrusion, 6...
...Acicular magnetic particles, 7...Resin, 9.12...
...magnetic layer, 1o...abrasive, 13...
...PET film. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 200, Iρ running poem (
3rd figure 0.1 0.3 f), 4 7 3
S 10v i+ +s sr ノII
ILIζ (r1+z) Figure 4 Figure 5 Figure 6 1 Base film

Claims (2)

[Claims] (1) It is characterized by comprising an organic film formed on the surface of a longitudinal recording medium, acicular magnetic particles formed perpendicularly on the surface of the organic film, and an organic material filling the spaces of the acicular magnetic particles. magnetic recording medium. (2) A magnetic recording medium according to claim 1, characterized in that an abrasive is kneaded into an organic material.