JPS5877033A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide a magnetic recording medium having excellent abrasion resistance by providing a protective layer consisting of aluminum nitride on a ferromagnetic thin metallic film layer. CONSTITUTION:A film 1 formed with a ferromagnetic thin metallic layer is transferred from the stock roll 5 is vacuum vessel 2 to a take-up roll 8 along the circumferential side surface of a cylindrical can 3 via guide rolls 6, 7, and gaseous nitrogen and gaseous argon are introduced through a gas introducing pipe 10; at the same time, aluminum is sputtered thereon from a target 4 consisting of aluminum, whereby a protective layer of aluminum nitride of 0.7- 1.3 ratio of nitrogen to aluminum N/Al is formed on the ferromagnetic thin metallic film layer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the improvement of a magnetic recording medium in which a protection layer is provided on the surface of a magnetic layer, and an object thereof is to improve durability.

In recent years, magnetic recording media with a ferromagnetic metal thin film layer as a recording layer, which has been developed in response to higher density magnetic recording, are usually deposited on a substrate such as a polyester film by vacuum deposition of ferromagnetic metals or their alloys. Made by coating on top of
``Although it has characteristics suitable for high-density recording, on the other hand, it has a large coefficient of friction with the magnetic head, making it susceptible to wear and damage and lacking in durability.

Therefore, such ferromagnetic gold F! Attempts have been made to improve durability by methods such as providing a protective layer on the 14N film layer. For example, it has been proposed to provide a protective layer made of titanium nitride on the magnetic gold jI4 thin film layer by vacuum evaporation or the like. .

-However, although this protective layer made of titanium nitride improves durability, it is not sufficient.Furthermore, even though the protective layer made of titanium nitride improves initial wear resistance, repeated use significantly reduces wear resistance. and maintains good wear resistance for a long period of time. There was a point where I couldn't stand it.

The inventors conducted various studies in view of the above circumstances, and found that after forming a ferromagnetic metal thin film layer made of metals or their alloys on a substrate, Providing a retainer made of aluminum nitride with a nitrogen ratio N/Al of 0.7 or more and 1.3 or less not only improves the initial wear resistance 2 but also improves the wear resistance with repeated use. Excellent abrasion resistance is maintained without much deterioration, making it even more durable.
Even if a magnetic retainer WIP 4 is provided on a magnetic layer formed by bonding magnetic powder and an inder on a substrate, the same excellent abrasion resistance as described above is maintained and it is further improved. It was discovered that a magnetic recording medium with excellent durability could be obtained, and this invention was completed. .

In this invention, protection made of aluminum nitride, minium, on the magnetic layer! Formation of @ is carried out by directing aluminum vapor onto the magnetic layer in an atmosphere of nitrogen gas or a mixed gas of nitrogen gas and other inert gas by sputtering, ion blasting, vacuum evaporation, etc. The ratio of nitrogen to aluminum, N/Al, can be freely adjusted by adjusting the nitrogen gas pressure or the partial pressure of nitrogen gas in the mixed gas. AI is from 0.7□
If it is too small, the friction coefficient will be large and the abrasion resistance will not be sufficiently improved, whereas if it is larger than 1.3, the hardness of the protective layer will decrease and the durability will deteriorate. If the layer thickness is thinner than 5°A, sufficient abrasion resistance cannot be obtained, and the thickness is 1oo.

If it is thicker than A, the spacing loss will increase and have a negative effect on the electromagnetic conversion characteristics, so the nitrogen to aluminum ratio N
The protective layer made of aluminum nitride with /AI of 0.7 to 1.3 is dense and has appropriate hardness, and also has a lubricating effect, and sufficiently improves the wear resistance of the magnetic layer. ,
.

Suitable materials for forming the ferromagnetic metal thin film layer formed on the substrate include single metals such as iron, cobalt, and nickel, as well as alloys thereof and magnetic materials such as Co-P N Co-N1-P. A ferromagnetic metal thin film layer made of these magnetic materials is deposited on a substrate such as a plastic film by means such as vacuum evaporation, ion blasting, sputtering, and plating. In addition, the magnetic layer formed on the substrate is formed by applying a magnetic paint consisting of magnetic powder, binder, organic solvent, and other necessary components onto a substrate such as a plastic film, and drying it. γ-Fe as magnetic powder
20. Powder, Fe, O, powder, Co-containing γyFe203
Any of various conventionally known magnetic powders such as powder, Co-containing Fe, O, powder, and Fe powder can be used.

In addition, as binders, all conventionally used binders such as vinyl chloride-vinyl acetate/ruvinyl alcohol copolymer and polyurethane resin are used, and organic solvents such as cyclohexanone, methyl ethyl ketone, and toluene that dissolve the binder are used. Any of those commonly used can be used alone or in combination.

Next, embodiments of the invention will be described.

Example 1 Surface treatment (
After applying Ar gas (Ar gas, bombardment treatment), this is loaded into a vacuum evaporator and an oxygen gas pressure of 1X is applied onto the base film.
A ferromagnetic metal thin film layer was formed by vapor-depositing cobalt to a film thickness of 100 OA under a residual gas pressure of 10"5)-L and an argon gas pressure of 1X10")-L. Next, the polyester base film 1 on which a thin layer of ferromagnetic gold 1 was formed was placed in a vacuum chamber 2 with a cylindrical can 3 and a curved shape corresponding to the lower half of the cylindrical can 3, as shown in FIG. The raw material roll 5 of the device has targets 4 made of aluminum arranged above and below, and is transferred 11 along the circumferential side of a cylindrical can 3 via guide rollers 6, and wound up via guide rollers 7. It was set to be wound up on roll 8. Next, the exhaust system 9 evacuates the chamber 2, and nitrogen gas and argon gas are introduced from the gas introduction pipe 10 provided on the lower side wall of the vacuum chamber 2 to raise the nitrogen gas partial pressure inside the vacuum chamber 2 to 7×10".
3) -L, argon gas partial pressure is 1 × 10 Torr,
Sputtering was performed by applying a voltage between the cylindrical can 3 and the target 4 with a power of 200 W from the high frequency power source 11, and a protective layer made of aluminum nitride was formed on the ferromagnetic metal thin film layer on the surface of the polyester base film 1.

The spacing layer formed of aluminum nitride had an aluminum to aluminum ratio N/A1tI'i of 0.7 and a layer thickness of 100λ. This was then cut to a predetermined width to make magnetic tape. In addition, in FIG. 1, it is a 14U Denzen vacuum gauge.

Example 2 In Example 1, when performing sputtering, the nitrogen gas partial pressure in the vacuum chamber 2 was set to 0. Example 1 was repeated except that the partial pressure of the argon gas was changed to 0.01)-/l, and the ratio of nitrogen to aluminum, N/AI, was 1.01)-/l.
A protective layer made of aluminum nitride with a layer thickness of 10 OA was formed on a ferromagnetic metal thin film layer i to produce a magnetic tape. 2) - L, the argon gas partial pressure was l It was formed into a magnetic tape.

Example 4 A polyester base film 1') having an elastic metal film layer formed thereon in the same manner as in Example 1 was used, and as shown in FIG. The ion source 1 is placed above and below the vacuum chamber 2.
6 is moved along one side of the cylindrical can 3 via the guide roller 6 from the raw fabric rope 5 of the device in which the can 6 is arranged.
It was set to be wound up through the guide roller 7 and rerolled to the reroll 8, and at the same time, an aluminum sheet was set on the BN' boat 15. Next, the exhaust system 9 exhausts the air, and ionized nitrogen gas is introduced from the ion source 162 into the vacuum chamber 2. At the same time, the AC power supply 18 heats the BN boat 15 to evaporate aluminum, and the vacuum chamber 2 is heated.
A protective layer made of aluminum nitride was formed on the ferromagnetic metal thin film layer on the surface of the polyester base film 1 by vapor deposition under a nitrogen gas pressure of 3×10−'). The formed protective layer made of aluminum nitride was applied to aluminum. This was then cut to a predetermined width to make magnetic tape. In addition, in FIG. 2, the insulation introduction terminals are 19 and 2 degrees.

Comparative Example (Titanium was sputtered in the same manner as in Sister Example 2, except that sputtering was performed with the target of ff/ used when performing 1 sputtering on the ground side 2 facing down from a target made of aluminum to a target made of titanium. The ratio of nitrogen to Ti is 1.0 and the layer thickness is 100X
A protective layer made of titanium nitride was formed on the ferromagnetic metal heavy film layer 1 to produce a magnetic tape.

Regarding the magnetic tapes obtained in each example and comparative example,
To examine durability, each magnetic tape was assembled into a cartridge and the friction coefficient was measured at the initial stage and after running 500 times.

The table below shows the results.

As is clear from the table above, what was obtained with this invention? The magnetic tapes (Examples 1 to 4) each have a smaller coefficient of friction at the initial stage and after 500 runs than the conventional magnetic tape (comparative example), which indicates that the magnetic recording medium obtained by the present invention is wear-resistant. It can be seen that this excellent abrasion resistance is maintained and the durability is further improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an embodiment of an apparatus used in manufacturing a magnetic recording medium of the present invention, and FIG. 2 is a schematic cross-sectional view showing a corresponding embodiment.

Claims (1)

[Claims] 1. The ratio of nitrogen to aluminum N/At is 0.7~
A rigid recording medium characterized in that a protective layer made of aluminum nitride of 1.3 is provided on the surface of a magnetic layer.