JPH0150968B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a ferromagnetic metal thin film magnetic recording medium with improved running stability and durability. Vacuum evaporation, sputtering,
Ferromagnetic metal thin film type metal recording media formed on substrates made of polymer films such as polyester films, polyimide films, non-magnetic metal thin plates, etc. using vacuum film forming methods such as ion plating, are similar to conventional coated magnetic recording media. It is possible to dramatically improve the recording density compared to other recording media, but in order to achieve this higher density, the gap in the magnetic head must be made smaller and the surface of the magnetic recording medium must be made smoother. It is necessary to reduce spacing loss as much as possible. A specific spacing value is required to be 500 Å or less, more preferably 300 Å or less. Although head touch and runnability can be considerably improved by finely controlling the surface shape of the magnetic recording medium, it is essentially difficult to significantly reduce the contact area between the head and the medium, and the coefficient of friction is The tendency to increase is inevitable. In addition, ferromagnetic metals are generally prone to corrosion in high humidity, and in order to avoid this corrosion, it has been proposed to improve the magnetic layer by alloying it, adding oxygen, and the like, as well as applying rust preventive agents. Rust inhibitors are usually compounds that have a specific magnetic group that binds to ferromagnetic metal ions, and prevent rust by adsorbing onto a ferromagnetic thin film, but they also have the effect of improving head touch and running properties. It has become clear that there is little to no adhesion, and that excessive adhesion causes clogging of the head. On the other hand, the use of various lubricants has been proposed for the purpose of lowering the coefficient of friction between the head and the magnetic recording medium, but with the exception of special lubricants, these lubricants do not exhibit any rust-preventing effect and may sometimes act as corrosion promoters. It has become clear that there may be cases. The present invention relates to a structure that can compensate for the drawbacks of the above-mentioned rust preventives and lubricants and take advantage of their advantages, and relates to a ferromagnetic metal thin film type magnetic recording medium with excellent running stability and durability. . That is, the present invention relates to a magnetic recording medium characterized in that a ferromagnetic metal thin film layer is provided on a nonmagnetic substrate containing a rust preventive agent, and a lubricant layer is provided on the ferromagnetic metal thin film layer. As the nonmagnetic substrate, generally used are plastic films such as polyester films, polyamide films, and polyimide films, metal plates such as aluminum plates and stainless steel plates, and inorganic plates such as glass plates and ceramic plates. These substrates contain a rust preventive agent as described below. A method for manufacturing a substrate containing a rust preventive agent is, for example, a method in which at least the surface of the nonmagnetic substrate is made finely porous by etching or the like, and a rust preventive agent is contained inside the nonmagnetic substrate. There is a method in which a rust preventive agent is added to the substrate raw material or a surface shape imparting agent at the time of film formation, or a method in which the substrate is immersed in a rust preventive solution to allow the rust preventive agent to penetrate into the substrate. The rust preventive agent may exist uniformly within the nonmagnetic substrate, but it may also be unevenly distributed near the surface of the nonmagnetic substrate.
It may be segregated into fine particles. The ferromagnetic metal thin film layer can be formed by depositing iron, cobalt, nickel, or an alloy containing these as main components directly on the substrate by vacuum evaporation, ion plating, sputtering, etc.
A thin film formed through a non-magnetic base thin film such as titanium or ROM, or a thin film formed by inserting the above-mentioned non-magnetic thin film as an intermediate separator between a ferromagnetic thin film, etc. can be used. There is a need for a thin film that improves adhesion strength to the substrate, corrosion resistance, magnetic properties, etc. by containing oxygen (partially oxidizing the metal). Regarding the latter, Japanese Patent Publication No. 56-23208 and Japanese Patent Application Laid-open No. 53-1982
Publication No. 42010, Japanese Unexamined Patent Publication No. 15014, Japanese Unexamined Patent Publication No. 1987-15014
-Described in Publication No. 37719, etc. As a rust preventive agent to be included in a non-magnetic substrate,
There are dihydric phenols, diallyl ketones, alkylphenols, naphthols, quinones, nitroso compounds, oxime compounds, etc. These are shown in more detail as follows. Divalent phenols include pure phenols such as hydroquinone, resorcinol, and catechol, and their alkylamino, nitro, nitroso,
Halogeno-substituted products, such as 2-methylhydroquinone, 4-methylresorcinol, 5-methylresorcinol, 4-methylpyrocatechol,
2,5-dimethylhydroquinone, 4,6-dimethylresorcinol, 2,5-dimethylresorcinol, 2-isopropyl-5-methylhydroquinone, 2-tert-butylhydroquinone, 2,
5-di-tert-butylhydroquinone, 4-tert
-Butylcatechol, 2-aminoresorcinol, 2-nitroresorcinol, 2,5-dichlorohydroquinone, etc. Diallyl ketones refer to benzophenone and its derivatives, such as benzophenone,
4-methylbenzophenone, 3-methylbenzophenone, 3,4-dimethylbenzophenone, 4,
Alkyl substituted products such as 4'-dimethylbenzophenone, 3,4'-dimethylbenzophenone, 4-ethylbenzophenone, 4-hydroxybenzophenone, 4,4'-dihydroxybenzophenone, 2,
3,4-trihydroxybenzophenone, 2,4
-dihydroxybenzophenone, 2,2',5,
6′-tetrahydrobenzophenone, 2,3′,4,
Hydroxybenzophenones such as 4',6-bentahydroxybenzophenone, aminobenzophenones such as 4-aminobenzophenone, 4,4'-diaminobenzophenone, or two or more substituents. benzophenones having, for example, 4-methoxy-2-hydroxybenzophenone, 2,
It refers to 2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,6-dihydroxy-4-methoxybenzophenone, etc. Alkylphenol refers to an alkyl substituted product of monovalent phenol, such as o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, 2,3-dimethylphenol. ,
2,5-methylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5
-dimethylphenol, 2,4,6-trimethylphenol, 2,4,5-trimethylphenol, 5-isopropyl-2-methylphenol, 2
-Isopropyl-5-methylphenol, p-
tert-butylphenol, 2,6-di-tert-butyl-p-cresol, 4,4'-methylenebis-
2,6-di-tert-butylphenol, 2,6-
Dimethyl-4-tert-butylphenol, 2-
tert-aluminum-4-methylphenol, 2-methyl-4,6-di-tert-butylphenol, 2,
4,6-tri-tert-butylphenol, etc. Naphthols are α-naphthol, β-naphthol, 1,2-naphthalene diol, 1,4,
Pure naphthols such as 5-naphthalenetriol, 1,2,5,8-naphthalenetetraol, and nitro-, nitroso-, amino-, and halogeno-substituted naphthols, such as 1-chloro-2-naphthol, 2,4-dichloro- 1-naphthol, 1-
Nitro-2-naphthol, 1,6-dinitro-2
-Naphthol, 1-nitroso-2-naphthol,
2-nitroso-1-naphthol, 1-amino-2
- Refers to naphthol, etc. Quinones include quinones without substituents such as p-benzoquinone, O-benzoquinone, 1,2-naphthoquinone, 1,4-naphthoquinone, 2,6-naphthoquinone, anthraquinone, 9-10-phenanthrenequinone, and diphenoquinone. , methylquinones such as methyl-P-benzoquinone, 2,3-dimethyl-P-benzoquinone, 2-methyl-1,4naphthoquinone, 2-methylanthraquinone, 2,5-
Dihydroxy-P-benzoquinone, Tetrahydroxy-P-benzoquinone, 5-hydroxy-1,
4-naphthoquinone, 2,3-dihydroxy-1,
4-naphthoquinone, 5,8-dihydroxy-1,
4-naphthoquinone, 2-hydroxyanthraquinone, 1,2-dihydroxyanthraquinone, 1,
2,3-trihydroxyanthraquinone, 1,
2,4-trihydroxyanthraquinone, 1,
2,5-trihydroxyanthraquinone, 1,
2,6-trihydroxyanthraquinone, 1,
Hydroxyquinones such as 2,7-trihydroxyanthraquinone, aminoquinones such as 2-amino-anthraquinone and 1,2-diaminoanthraquinone, 1-nitroanthraquinone, 1,5-
Nitroquinones such as dinitroanthraquinone,
Halogenoquinones such as 2,6-dichloro-P-benzoquinone, tetrachloro-P-benzoquinone, and tetrafuromo-P-benzoquinone, or quinones having two or more types of substituents, such as 2,
5-dichloro-3,6-dihydroxy-P-benzoquinone, 1-methyl-2-hydroxy-1,4
- Refers to naphthoquinone, etc. A nitroso compound is an organic compound having both a hydroxyl group and a nitroso group, and includes nitrosophenol-based and nitrosonaphthol-based organic compounds. Specifically, 1-nitroso-2-naphthol, 2-nitroso-1-naphthol, 1-nitroso-2-naphthol-3-6-disulfonic acid sodium salt (nitroso R salt), 4-nitroso-
2-methoxy-1-phenol, 4-nitroso-
2-ethoxy-1-phenol, 4-nitrosocarvacrol, 6-nitroso-O-cresol,
4-nitroso-m-cresol O-nitrosophenol, 2-nitrosoresorcin, 4-nitrosoresorcin, 2-nitrosoresorcin monomethyl ether, N-nitrosophenylhydroxylamine ammonium salt (cuperone), P-nitrosophenol, 2-nitrosoresorcin -1-Naphthol-4
-Sulfonic acid, 5-nitroso-8-quinolinol, etc. The oxime compound refers to benzyloxime, glyoxime, benzaldoxime, benzamide oxime, α-benzoin oxime, acetophenonexime, benzophenonexime, dimethylglyoxime, salicylaldoxime, and the like. The rust preventive content of the non-magnetic substrate should be at least near the surface of the non-magnetic layer (i.e., at a depth from the surface).
(within 1000Å) and preferably 0.001 to 10% by weight
A suitable amount is 0.01 to 1% by weight, and the amount inside the nonmagnetic layer may be equal to or lower than that near the surface. The lubricant layer is mainly composed of the lubricant described below, and may optionally contain a binder made of various polymeric materials, the above-mentioned rust preventive agent, antistatic agent, antifungal agent, etc. As the lubricant, fatty acids, fatty acid esters, fatty acid amides, metal soaps, aliphatic alcohols, paraffins, silicones, fluorine-based surfactants, etc. can be used. Fatty acids include lauric acid, myristic acid,
Palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, etc. with 12 or more carbon atoms
22 items are available. Fatty acid esters include ethyl stearate, butyl stearate, amyl stearate,
Stearic acid monoglyceride, palmitic acid monoglyceride, oleic acid monoglyceride, pentaerythritol tetrastearate, etc. can be used. Examples of fatty acid amides include caproic acid amide, capric acid amide, lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, olefinic acid amide, linoleic acid amide, methylene bisstearic acid amide, ethylene bis stearic acid amide, etc. Can be used. Metal soaps include zinc, laelic acid, myristic acid, valmitic acid, stearic acid, behenic acid, olefinic acid, linoleic acid, linolenic acid, etc.
Salts, lauryl, palmityl, myristyl, stearyl, with lead, nickel, cobalt, iron, aluminum, magnesium, strontium, copper, etc.
Sulfonic acids such as behenyl, oleyl, linole, linolene, etc., and salts of the above-mentioned various metals can be used. As the aliphatic alcohol, cetyl alcohol, stearyl alcohol, etc. can be used. As paraffin, n-octadecane, n-
nonadecane, n-tridecane, n-docosane, n
- Saturated hydrocarbons such as dotriacontane can be used. As silicones, polysiloxanes in which hydrogen is partially substituted with alkyl groups or phenyl groups, and those modified with fatty acids, aliphatic alcohols, acid amides, etc. can be used. Examples of fluorine-based surfactants include salts of perfluoroalkyl carboxylic acids and perfluoroalkyl sulfonic acids with sodium, potassium, magnesium, zinc, aluminum, iron, cobalt, nickel, etc., perfluoroalkyl phosphate esters, and perfluoroalkyl phosphates. Alkyl betaine, perfluoroalkyltrimethylammonium salt, perfluoroethylene oxide, perfluoroalkyl fatty acid ester, etc. can be used. To form a lubricant layer on the surface of a ferromagnetic metal thin film, the above lubricant or a mixture of various additives added thereto can be diluted with a solvent and applied thinly onto the ferromagnetic metal thin film, or the lubricant vapor can be applied to the surface. Do this using methods such as In this case, the lubricant may be used alone or as a mixture of multiple types. It is also possible to perform heat treatment after forming the lubricant layer in order to stabilize the lubricant layer. The thickness of the lubricant layer is preferably 500 Å or less, preferably 200 Å or less. When the ferromagnetic thin film has a columnar crystal structure formed by oblique vapor deposition, a lubricant layer may be formed over the entire surface of the columnar crystal, but even if the lubricant is locally deposited on the surface, The effects of the present invention can be obtained. In the magnetic recording medium of the present invention, the rust preventive agent contained in the nonmagnetic substrate is applied to the crystal interface of the ferromagnetic metal crystal structure constituting the ferromagnetic thin film during formation of the ferromagnetic thin film or during actual use of the medium. By diffusing to the crystal surface through the gaps existing in the
The entire crystalline structure is protected by the rust preventive agent, improving the corrosion resistance of the magnetic layer. In addition, many rust preventives themselves generally have poor lubricity, and if they are applied directly to the magnetic layer surface and are present in excess, head clogging may occur when media are used. If so, there will be no excess rust preventive on the surface of the medium, and the head will not be clogged. Furthermore, by forming a lubricant layer on the surface of the medium, the coefficient of friction is also significantly reduced, resulting in improved durability. Next, examples of the present invention will be described. A biaxially stretched polyester film with a thickness of 12 μm and good surface properties was mixed with 1% by weight of various rust preventive agents listed in the attached table.
The film was immersed in various dissolved phenol solutions to allow the solutions to penetrate into the film, and then dried to remove the solvent. Subsequently, the rust preventive agent adhering to the film surface was removed by washing with alcohol. Each of these films contained 0.01 to 0.1% by weight of each rust inhibitor. These films were placed along the circumference of a cylindrical can, and a CoNi alloy (Ni ^content 20 wt.
%) was continuously obliquely deposited (cutting the low incident angle component 30° or less) to form a 1000 Å thick oxygen-containing CoNi ferromagnetic thin film (Sample A).
A CoNi ferromagnetic thin film containing no oxygen was formed under similar conditions to the above at a vacuum level of 5 x 10 ^-6 Torr and without introducing oxygen gas (Sample B).
prepared. In addition, as a comparison sample, a ferromagnetic thin film was formed on the polyester film before the above-mentioned rust preventive treatment under the same conditions as above. The sample that did not cause any damage was designated as sample B'. As a result of measuring oxygen in the film mainly using Augier electron spectroscopy,
The average amount of oxygen in the films of Samples A and A' was 10% in atomic ratio (O/Co+Ni x 100) to Co and Ni, and that of Sample B was less than 1%. A lubricant layer was formed by applying various lubricants dissolved in ethyl alcohol, acetone, ethyl acetate, toluene, etc. to the surfaces of these samples and then drying them. (The coating amount was adjusted to be 10 to 100 mg/ ^m2 .) Thereafter, these samples were slit to a predetermined width to form magnetic tapes. These tape samples were heated to 90% at 50℃.
Leave it in an RH atmosphere, during which time 3
Sample B was taken out and recorded and played back on a video deck every day to check for clogging, and the surface of the magnetic layer side was also observed under a microscope to check for rust. The results are shown in the attached table.

[Table] The above examples relate to CoNi-based magnetic thin films, but this effect can be seen in Co thin films, Fe--Ni thin films, Fe-Ni thin films, and Fe-Ni thin films.
- Similar results were found in Co thin films. Furthermore, a ferromagnetic thin film containing oxygen is more effective than a pure metal thin film, and this tendency is noticeable when the oxygen content is 3 to 45%. As is clear from the above, the magnetic recording medium of the present invention has improved overall durability including corrosion resistance, runnability, and head clogging, and has great practical value.

Claims (1)

[Claims] 1. On a non-magnetic substrate containing 0.001 to 10% by weight of a rust inhibitor selected from divalent phenols, diallyl ketones, alkylphenols, naphthols, quinones, nitroso compounds, and oxime compounds at least near the surface. A magnetic recording medium, comprising: a ferromagnetic metal thin film layer containing 3 to 45% oxygen atoms in terms of atomic ratio to the ferromagnetic metal; and a lubricant layer provided on the ferromagnetic metal thin film.