JPH0196821A - Magnetic recording medium and production thereof - Google Patents

Abstract

PURPOSE:To improve both corrosion resistance and traveling property by forming a passive layer on the surface of a thin ferromagnetic metallic film layer constituting a magnetic recording medium, then providing a rust inhibitor layer essentially consisting of nitrosonaphthol or further, providing a fluorine lubricating agent layer thereon. CONSTITUTION:The thin ferromagnetic metallic film layer is formed on a poly ethylene terephthalate film substrate by executing vapor deposition of Co-Ni (80-20) in oxygen atmosphere; thereafter, an atmosphere treatment essentially consisting of oxygen is executed to form the passive cobalt layer on the surface of the thin metallic film. Further, a 0.05wt.% benzene soln. of the 2-nitroso-1- naphthol is coated on the passive layer and is dried. The nitrosonaphthol is a cathode inhibitor contg. nitrogen in the molecular structure thereof and suppresses mainly the hydrogen generation reaction among the corrosion reactions by the moisture in the atm. air or corrosive gases so as to enhance the rust inhibitive effect. The fluorine lubricating agent layer is provided on the naphthol layer at need.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium and a method for manufacturing the same, and particularly to a magnetic recording medium having excellent corrosion resistance and excellent runnability, and the manufacturing thereof. Regarding the method.

[Conventional technology]

So far, aromatic carboxylic acids having an amino group (Sho No. 58-194131), cuperones (Sho No. 58-194131), cuperones (Sho No. No. 58-194138) and polyamines (Jikai No. 59-3724) have been proposed, and some of them are in practical use.

Corrosive environmental factors for ferromagnetic metal thin films include humidity, sulfur dioxide (sulfur dioxide) gas, nitrogen oxide gas, etc., and Toyo's rust preventive agent has a universal corrosion-resistant effect against these corrosive factors. However, it has the drawback that it cannot be said to have a sufficient rust prevention effect in the actual complex corrosive environment.

Furthermore, when the surface of a ferromagnetic metal thin film is a high-order oxide that has relatively corrosion resistance, a rust preventive agent that has a reducing property has the property of destroying the oxide. However, rust preventives have not been selected from this perspective.

[Problem to be Solved by the Invention 1] Regarding the corrosion resistance of ferromagnetic metal thin films, the prior art had various drawbacks as described above.

The present invention solves these drawbacks and provides a magnetic recording medium with excellent corrosion resistance and a method for manufacturing the same.

An object of the present invention is to provide a magnetic recording medium with improved running performance when the running performance is degraded due to corrosion resistance measures, and a method for manufacturing the same.

[Means for solving problems]

The above purpose is to form a passive layer on the surface of a ferromagnetic metal thin film provided on a non-magnetic substrate, and then to deposit nitrosonaphthol on the passive layer, or to further deposit nitrosonaphthol on the nitrosonaphthol adhesion layer. This can be achieved by forming a fluorine-based lubricant layer.

[For production]

Nitrosonaphthol is a so-called cathode inhibitor containing nitrogen in its molecular structure, and exhibits a rust-preventing effect by mainly inhibiting hydrogen generation reactions among the corrosion reactions caused by atmospheric moisture or corrosive gases.

The aforementioned cuperones and polyamines also act as cathode inhibitors.

The reason why the rust prevention effect differs under the same corrosion conditions is due to the difference in adsorption affinity for ferromagnetic metals (if it is weak, there is no rust prevention effect, but if it is too strong, corrosion will progress), and the difference in molecular structure. This is thought to be due to (differences in coverage due to steric hindrance, etc.), and nitrosonaphthol is superior in these respects, so it has a remarkable rust prevention effect.

Furthermore, since nitrosonaphthol does not have a reducing effect on higher-order oxides, when a nitrosonaphthol layer is formed on a ferromagnetic metal thin film layer with a passive layer formed on the surface, due to the synergistic effect with the presence of the passive layer, It is possible to significantly improve corrosion resistance.

In addition, when a nitrosonaphthol layer is provided on the magnetic layer,
There is a tendency to slightly increase the coefficient of friction when sliding with the magnetic head, but this phenomenon can be countered by providing a fluorine-based lubricant layer on the nitrosonaphthol layer, which can be used satisfactorily for a long period of time. It is possible to ensure good running performance.

〔Example〕

Examples of the present invention will be described below along with comparative examples.

Example 1 A polyethylene terephthalate film substrate having a thickness of 9/ffi was coated with a film having a thickness of 1500 mm under an oxygen atmosphere.

-N i (80-20) is vapor-deposited to create a ferromagnetic metal thin film layer, and then a cobalt passive film is formed on the surface of the metal thin film by treatment in an atmosphere containing oxygen as a main component. A 0.05% benzene solution of 2-nitroso-1-naphthol was applied onto the working membrane and dried to prepare a sample.

The above-mentioned passive film was formed by, after forming the ferromagnetic metal thin film layer, placing the container in a separate container and reducing the pressure to 20 Torr, then filling the container with 1 atm of oxygen and treating it for 3 days.

Example 2 A sample was prepared in the same manner as in Example 1 except that 1-nitroso-2-naphthol was used instead of 2-nitroso-1-naphthol in Example 1.

Comparative Example 1 A sample was prepared in the same manner as in Example 1 except that the 2-nitroso-1-naphthol solution was not applied.

Comparative Example 2 No cobalt passive layer was provided in Example 1, and 2-
A sample was prepared in the same manner as in Example 1 except that the nitroso-1-naphthol solution was not applied.

Comparative Example 3 A sample was prepared in the same manner as in Example 1 except that cuperone was used instead of 2-nitroso-1-naphthol.

Comparative Example 4 A sample was prepared in the same manner as in Example 1 except that the cobalt passive layer was not provided.

For the above six types of samples, 60'
Decrease rate of saturation magnetization when left in C90%RH atmosphere for one week and 5021. OPPM, H2S 0.5P
P.M.

No. 21.0 PPM, 1 in an atmosphere of 35°C and 75% RH
Sulfur content in the metal magnetic film layer after standing for 00 hours (
M%) was measured and the corrosion resistance was compared.

The results are shown in Table 1.

From the results in Table 1, it can be seen that the sample in which a nitrosonaphthol layer was provided on the magnetic layer with a passive layer (Example 1.2) was different from the sample in which the nitrosonaphthol layer was not provided on the magnetic layer or in place of the nitrosonaphthol layer. Compared to the sample in which a cuperone layer was provided (Comparative Example 1.2゜3) and the sample in which no cobalt passive layer was provided (Comparative Example 4), it was superior in both saturation magnetization reduction rate and sulfur content, It is known to exhibit good corrosion resistance.

Example 3 After providing a 2-nitron-1-naphthol layer on the passive film layer on the surface of the ferromagnetic metal thin film layer in the same manner as in Example 1, further A sample was prepared by applying a 0.1% by weight Freon solution of fluorine thread lubricant Fomblin ZDOL (manufactured by Nippon Montageson).

Example 4 A sample was prepared in the same manner as in Example 3 except that Fomblin ZDOL in Example 3 was replaced with Fomblin Z25 (manufactured by Nippon Montegin Co., Ltd.).

Example 5 A sample was prepared in the same manner as in Example 3, except that Fomblin Z D-OL in Example 3 was replaced with Fomblin AM2001 (manufactured by Nippon Montageson).

Comparative Example 5 A sample was prepared in the same manner as in Example 3 except that the nitrosonaphthol layer was not provided.

Comparative Example 6 Example 3 except that the order of coating Fomblin ZDOL and forming the nitrosonaphthol layer was reversed.
A sample was prepared in the same manner.

The above five types of samples were tested as accelerated corrosion tests.

Reduction rate of saturation magnetization when left in an atmosphere of 60°C and 90% RH for one week and S021.0PPM, H,80,
5PPM, NO, 1,OPPM, 35℃, 75%R
The sulfur content (atomic %) in the metal magnetic film layer after being left in an H atmosphere for 100 hours was measured. Also, to evaluate running properties, each sample was made into a @8m tape and #20
A 4 m diameter SUS bottle polished with 0.00 abrasive was brought into contact with a winding angle of 90" and a load of 20 g per weight was applied.
The static friction coefficient was measured after 00 reciprocations of friction.

The results are shown in Table 2.

From the results in Table 2, a sample according to the present invention (Example 3. It is known that Sample No. 4.5) exhibits superior performance in both corrosion resistance and runnability compared to Comparative Examples S and 6. In this example, 2-nitroso-1
-Although only naphthol was described, 1-nitroso-
A similar effect is observed for 2-naphthol.

In addition, in the formation of the nitrosonaphthol layer and the fluorine-based lubricant layer described above, it is also possible to apply the coating directly on each base layer, or to apply it on the back side of the substrate and apply it to each base layer during winding. Exactly the same characteristic results were obtained when it was transferred onto a geological layer, and no differences were observed due to the coating method.

〔Effect of the invention〕

As described above, regarding a magnetic recording medium comprising a ferromagnetic metal thin film layer provided on a nonmagnetic substrate, a passive layer is formed on the surface of the metal thin film layer, and nitrosonaphthol is mainly formed on the passive layer. By forming a rust preventive layer as a component, or by further providing a fluorine-based lubricant layer on the rust preventive layer, a magnetic material with significantly superior corrosion resistance and runnability compared to conventional technology. can obtain a recording medium,
Additionally, we were able to establish a manufacturing method.

Representative patent attorney: Junnosuke Nakamura

Claims (1)

[Claims] 1. In a magnetic recording medium comprising a ferromagnetic metal thin film layer provided on a non-magnetic substrate, after forming a passive layer on the surface of the metal thin film layer, nitrosonaphthol is added to the surface of the passive layer. A magnetic recording medium characterized by forming a rust preventive layer containing as a main component, or further providing a fluorine-based lubricant layer on the rust preventive layer. 2. After forming a passive layer on the surface of a ferromagnetic metal thin film provided on a non-magnetic substrate, on the passive layer, either by direct coating or by transfer from the coated surface coated on the back side of the substrate, Production of a magnetic recording medium characterized by depositing nitrosonaphthol, or further forming a fluorine-based lubricant layer on the surface to which nitrosonaphthol is deposited, either by direct coating or by transfer from the back surface of the substrate. Method.