JPS6057533A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve durability and corrosion resistance by providing a thin metallic film layer consisting of metals of >=1 kind among Cr, Ti, Al and Ta on the surface of a thin ferromagnetic metallic film layer, oxidizing or nitriding the surface and forming the oxide or nitride of the metals. CONSTITUTION:A thin metallic film layer 9 consisting of metals such as Cr, Ti, Al, Ta, etc. or an alloy thereof is provided on a thin ferromagnetic metallic film layer 8 and the surface thereof is oxidized or nitrided to form an oxide film layer or nitride film layer 10 consisting of the oxide or nitride of the metals. The layers 8 and 9 have good adhesiveness and the oxide film layer or nitride film layer 10 is dense, hard, small in coefft. of friction and is highly resistant to wear and corrosion. The oxidation (nitriding) of the surface of the layer 9 is accomplished by exposing the layer 9 to the inside of the plasma of gaseous oxygen (gaseous nitrogen). The thickness of the layer 9 is made 30-1,000Angstrom and the thickness of the oxide (nitride) film layer 10 is made 20-100Angstrom .

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium having a ferromagnetic gold film layer as a recording layer, and an object thereof is to provide the above-mentioned magnetic recording medium having excellent durability and corrosion resistance. It is in.

A magnetic recording medium whose magnetic recording layer is a ferromagnetic metal thin film layer is
Generally, they are made by depositing metals or their alloys on a base film by vacuum evaporation, sputtering, etc., and have characteristics suitable for high-density recording, but they are less sensitive to magnetic heads than coated magnetic recording media. The coefficient of friction is large, resulting in poor running performance and being susceptible to wear and damage. Another disadvantage is that it is gradually oxidized in the air, resulting in deterioration of magnetic properties such as maximum magnetic flux density.

For this reason, conventionally, ferromagnetic metal thin I! Attempts have been made to improve durability and corrosion resistance by providing various protective film layers, such as a protective film layer made of a lubricant, on the 2i layer, but satisfactorily results have not yet been obtained.

As a result of various studies in view of the current situation, the inventors provided a thin metal MIW made of metals such as chromium, titanium, aluminum, tantalum, or alloys thereof on this ferromagnetic metal thin film layer, and Oxide 19 made of metal oxide or nitride by oxidizing or nitriding the surface of the layer
When a layer or a nitride film layer is formed on the surface of a thin metal film layer, a ferromagnetic metal thin film 1Iii! A metal thin film layer made of the above-mentioned metal or alloy is firmly adhered with good adhesion over 1 m above the surface, and a 19-layer thin metal oxide film layer made of the above-mentioned metal or alloy is formed on the surface of this metal thin film layer. Alternatively, it was discovered that the nitride film layer is dense and hard, has a small friction coefficient, and has excellent wear resistance and corrosion resistance, so that durability and corrosion resistance are sufficiently improved, and this invention has been completed.

In this invention, the metal thin film layer is formed on the ferromagnetic metal thin film layer by depositing metals such as chromium, titanium, aluminum, tantalum, or alloys thereof on the ferromagnetic metal by vacuum deposition, sputtering, ion blating, etc. This is done by a method such as depositing it on a thin film layer.

In this way, this type of metal thin film layer is formed by depositing a ferromagnetic material on a substrate by vacuum evaporation, sputtering, ion blating, etc., and then immediately subsequently depositing the ferromagnetic material on the ferromagnetic metal thin film layer by the same method. It is easy to form the metal thin film layer, and the surface of the metal thin film layer can be easily oxidized and nitrided. Further, this type of metal thin film layer has extremely good adhesion to the ferromagnetic metal thin film layer, and therefore is formed firmly on the ferromagnetic metal thin film layer. Layer thickness is 30
], preferably within the range of 000 people; if it is thinner than 30 people, the corrosion resistance and durability will not be sufficiently improved, and if it is thicker than 1000 people, there is a risk that the spacing loss will increase and the sensitivity will decrease. There is.

The surface of the metal thin film layer thus formed was oxidized by exposing the metal N film layer to plasma of oxygen gas generated by a high frequency electrode, an AC electrode, or a DC electrode to turn it into plasma in a processing tank. This is done by bringing oxygen gas into contact with the metal thin film layer, and when the plasma-formed oxygen gas is brought into contact with the metal thin-film layer, the plasma-formed oxygen gas has high energy, so the surface of the metal thin film layer is heated. oxidizes rapidly at low temperatures, and a dense film grows from the surface to cover the metal surface. In addition, the surface of the metal thin film layer can be oxidized by thermal oxidation or ultraviolet accelerated oxidation in an oxygen gas atmosphere. An oxide film layer made of an oxide of the alloy is well formed on the surface of the gold B thin film layer. The thickness of the oxide film layer formed in this way is preferably within the range of 20 to 100 layers,
If it is thinner than 20 people, the desired effect may not be obtained. In addition, when plasma oxygen gas is brought into contact with the surface of the metal thin film layer, the gas pressure of the oxygen gas in the processing tank is
When generating oxygen gas plasma with a high frequency electrode, I
If it is lower than 3 Torr, no discharge will occur, and if it is higher than 3 Torr, it will have a negative effect on the plastic film used as the base. When generating oxygen gas plasma at the electrode, if it is lower than 3×10 → Torr, no discharge will occur, and if it is higher than 5 Torr, it will have a negative effect on the plastic film, so it should be 3×10′ or higher.
Preferably, it is within the range of 5 torr.

In addition, nitriding the surface of a metal thin film layer can be done by exposing the metal thin film layer to nitrogen gas plasma generated by a high frequency electrode, an AC electrode, or a DC electrode. When nitrogen gas that has been turned into plasma in this way is brought into contact with the metal thin film layer, the nitrogen gas that has turned into plasma has high energy, so that the metal thin film layer is heated. The surface of the layer is quickly nitrided at low temperature, and a dense film grows from the surface, so that a nitride film layer made of metal or alloy nitride is well formed on the surface. The N thickness of the nitride film layer formed in this way is 20 to 10
It is preferable to keep the amount within the range of 0 people, and if it is less than 20 people, there is a risk that the desired effect may not be obtained. In addition, when bringing nitrogen gas into plasma into contact with the surface of the metal thin film layer, the gas pressure of the nitrogen gas used in the processing tank is controlled by a high-frequency electrode, as in the case of oxygen gas during oxidation. When generating an AC current, if it is lower than 1 x 10-yotorr, no discharge will occur, and if it is higher than 3 torr, it will have a negative effect on the plastic film used as the substrate, so it is preferable to keep it within the range of lXl0-' to 3 torr. When generating nitrogen gas plasma with electrodes and DC electrodes, if the temperature is lower than 3X10'L, no discharge will occur, and if it is higher than 51L, it will not have a negative effect on the plastic film; It is preferable to keep it within the range of

Materials for forming the ferromagnetic metal thin film layer include Co, Fc, and N.
i, Co-Ni alloy, Co-Cr alloy, Co-P alloy, 0. Ferromagnetic materials such as o-Ni-P alloy are used,
A ferromagnetic metal thin film layer made of these ferromagnetic materials is deposited on a substrate by means such as vacuum evaporation, ion blasting, sputtering, or plating.

In addition, as magnetic recording media, polyester film,
Various types of structures that come into sliding contact with magnetic heads, such as magnetic tapes based on synthetic resin films such as polyimide films, magnetic disks and magnetic drums based on disks and drums made of synthetic resin films, aluminum plates, glass plates, etc. includes.

Next, embodiments of the invention will be described.

Example 1 A polyester film with a thickness of 10μ was loaded into a vacuum evaporation apparatus, and a cobalt-nickel alloy (weight ratio 8:2) was heated and evaporated under a vacuum of 1X1O-5) to form a thick layer on the polyester film. A ferromagnetic metal thin film layer made of a cobalt-nickel alloy with a diameter of 0.1 μm was formed. Subsequently,
Chromium is heated and evaporated to a thickness of 30 mm on the ferromagnetic metal thin film layer.
A thin metal film layer consisting of zero chromium was formed. Then,
Using the plasma processing apparatus shown in FIG.
is moved along the circumferential side of the cylinder, set so as to be wound up on the winding roll 5, and oxygen gas is supplied from the gas introduction pipe 6 at 200 ml of oxygen gas.
Introducing at a flow rate of secm, oxygen gas pressure 0.1 torr,
Plasma treatment was performed with an output of 600 W from the AC electrode 7 to form a chromium oxide film layer on the surface of the metal thin film layer. Thereafter, it was cut to a predetermined width to produce a magnetic tape A in which a ferromagnetic metal thin film layer 8, a metal thin film layer 9, and an oxide film layer 10 were sequentially laminated on a polyester film 1 as shown in FIG. . The thickness of the oxide film layer 10 on the surface of the metal thin film layer at this time is estimated to be 100 people.

In the figure, 11 is an exhaust system for reducing the pressure inside the processing tank 2, and 12 is an AC power source for applying a high frequency to the electrode 7.

Example 2 A magnetic tape was produced in the same manner as in Example 1, except that in forming the metal thin film layer in Example 1, the thickness of the metal thin film layer made of chromium was changed to 100. The thickness of the oxide film layer formed on the surface of the thin metal tliji layer made of chromium at this time is estimated to be 50.

Example 3 A magnetic tape was produced in the same manner as in Example 1, except that in forming the thin metal HUB in Example 1, the thickness of the metal thin film layer made of chromium was changed to 50. The thickness of the oxide film layer formed on the surface of the metal thin film layer made of chromium at this time is estimated to be less than 50 people.

Example 4 The procedure was the same as in Example 1, except that in the formation of the metal thin film layer in Example 1, sputtering was performed instead of vacuum evaporation, and a 300 metal thin film layer made of chromium was formed on the ferromagnetic metal thin film layer. and made magnetic tape.

Example 5 In Example 1, the formation of a metal thin film layer made of chromium by vacuum evaporation was omitted, and a ferromagnetic metal thin film layer made of a cohartonisokel alloy (weight ratio 8:2) with a thickness of 0.1 μm was formed. Example 1 except that the polyester film was loaded into a plasma processing apparatus using a parallel plate type electrode and a chrome-plated stainless steel plate, and plasma processing was performed by introducing oxygen gas into the plasma processing apparatus. I made magnetic tape in the same way.

Example 6 In forming the metal thin film layer in Example 1, titanium was used instead of chromium, and a thickness of 300 mm was formed on the ferromagnetic metal thin film layer.
A magnetic tape was produced in the same manner as in Example 1 except that a metal thin film layer made of titanium was formed by sputtering. The thickness of the oxide film layer formed on the surface of the metal thin film layer made of titanium at this time is estimated to be 100 people.

Example 7 Same as Example 1 except that in forming the metal thin film layer in Example 1, aluminum was used instead of chromium and a metal N film layer made of aluminum with a thickness of 300 mm was formed on the ferromagnetic metal thin film layer. Magnetic tape was made in the same way. The thickness of the oxide film layer formed on the surface of the metal thin film layer made of aluminum at this time is estimated to be 100 people.

Example 8 In forming the metal thin film layer in Example 1, tankle was used instead of chromium, and a thickness of 30 mm was formed on the ferromagnetic metal thin film layer.
A magnetic tape was produced in the same manner as in Example 1 except that a metal thin film layer made of tantalum was formed by sputtering. The thickness of the oxide film layer formed on the surface of the metal thin film layer made of tantalum at this time is estimated to be 100 people.

Example 9 In Example 1, nitrogen gas was introduced into the processing tank 2 at a flow rate of 200 seconds instead of oxygen gas, and the nitrogen gas pressure was 0.
A magnetic tape was produced in the same manner as in Example 1, except that plasma treatment was performed at 1 Torr and output of AC electrode 7 was 600 W, and nitriding was performed. The thickness of the nitride film layer at this time is estimated to be 100 people.

Example 10 In Example 6, nitrogen gas was introduced into the processing tank 2 at a flow rate of 2'OOsccm instead of oxygen gas, and the nitrogen gas pressure was 0.
．． A magnetic tape was produced in the same manner as in Example 6, except that plasma treatment was performed at 1 Torr and output of AC electrode 7 was 600 W, and nitriding was performed. The thickness of the nitride film layer at this time is 100
Estimated to be a person.

Example 11 In Example 7, nitrogen gas was introduced into the processing tank 2 at a flow rate of 200 sec instead of oxygen gas, and the nitrogen gas pressure was 0.
．． A magnetic tape was produced in the same manner as in Example 7, except that plasma treatment was performed at 1 torr and AC electrode output of 600 w, and nitriding was performed. The thickness of the nitride film layer at this time is 100
Estimated to be a person.

Example 12 In Example 8, nitrogen gas was introduced into the processing tank 2 at a flow rate of 200 seconds instead of oxygen gas, and the nitrogen gas pressure was 0.
A magnetic tape was produced in the same manner as in Example 8, except that plasma treatment was performed at 1 Torr and AC electrode output of 600 W, and nitriding was performed. The thickness of the nitride film layer at this time is estimated to be 100 people.

Example 13 A magnetic tape was produced in the same manner as in Example 5, except that argon gas was introduced into the plasma processing apparatus to perform the plasma treatment.

In this case, the surface of the chromium metal thin film layer is activated by plasma treatment with argon gas, and when it is taken out into the air in this state, the surface of the activated chromium metal thin film layer is oxidized by oxygen in the air, forming an oxide film. is formed.

Comparative Example 1 A magnetic tape was produced in the same manner as in Example 1, except that the oxidation of the metal thin film layer and the surface of the metal thin film layer was omitted, and the upper surface of the ferromagnetic metal thin film layer was plasma-treated with argon gas.

Regarding the magnetic tapes obtained in each example and comparative example,
The durability was investigated by sliding the magnetic head and measuring changes in the coefficient of friction as the number of times the magnetic head slid was increased. Also,
The resulting magnetic tape was left under conditions of 60°C and 90% RH, and the deterioration rate of the maximum magnetic flux density over time was measured, with the maximum magnetic flux density of the magnetic tape before being left as 100%, and the corrosion resistance was evaluated. Examined. Figure 3 graphs the changes in the coefficient of friction, and Figure 4 graphs the changes in the deterioration rate of the maximum magnetic flux density. Graph A is the magnetic tape obtained in Example 1, and graph B is the graph obtained from the magnetic tape obtained in Example 1. Magnetic tape obtained in Example 2, graph C; magnetic tape obtained in Example 3, graph D
is the magnetic tape obtained in Example 4, and graph E is the magnetic tape obtained in Example 5.
Graph F is the magnetic tape obtained in Example 6, Graph G is the magnetic tape obtained in Example 7, Graph H is the magnetic tape obtained in Example 8, Graph ■
Graph J is the magnetic tape obtained in Example 10, graph L is the magnetic tape obtained in Example 11, and graph L is the magnetic tape obtained in Example 12. , graph M shows the magnetic tape obtained in Example I3, and graph N shows the magnetic tape obtained in Comparative Example 1.As is clear from these graphs, the magnetic tape obtained in Comparative Example 1 has a coefficient of friction of However, as the number of times the magnetic head slides increases, the coefficient of friction becomes very large.However, the magnetic tapes (Examples 1 to 13) manufactured in this invention all have small coefficients of friction and Even if the number of times the head slides increases, the coefficient of friction does not increase significantly, which indicates that the magnetic recording medium obtained by this invention has excellent durability.Also, the rate of deterioration of the maximum magnetic flux density is also the same. In addition, the magnetic tape obtained in Comparative Example 1 has a very high deterioration rate over time, but the magnetic tapes obtained in the present invention (Examples 1 to 13) all have a very high deterioration rate over time. However, the deterioration rate did not increase that much, and this shows that the magnetic recording medium obtained by the present invention has excellent corrosion resistance.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an example of a plasma processing apparatus used for oxidizing or nitriding a metal thin film layer, and FIG. 2 is a partially enlarged sectional view of a magnetic tape obtained by the present invention.
Fig. 3 is a diagram showing the relationship between the friction coefficient of the magnetic tape obtained by this invention and the number of times the magnetic head slides, and Fig. 4 is a relation diagram between the deterioration rate and elapsed time of the magnetic tape obtained by this invention. be. ■...Polyester film (substrate), 8...Ferromagnetic metal AV film layer, 9...Metal thin film layer, 10...Oxide film layer (nitride film layer), A...Magnetic tape ( Magnetic recording media) Patent applicant Kuchitachi Maxell Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 1. Form a ferromagnetic gold 17iS thin film layer made of a metal or an alloy thereof on a substrate, and form this ferromagnetic metal thin B'AM
A metal thin film layer made of at least one metal selected from chromium, titanium, aluminum, and tantalum is provided on the surface of the metal, and the surface of this metal film layer is oxidized or nitrided to form a metal oxide or nitride. Oxide layer or nitride! j! A magnetic recording medium characterized in that a layer is formed on the surface of a metal thin film layer.