JPH0355886B2 - - 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 deposition, sputtering,
Ferromagnetic metal thin film magnetic 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 running properties 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 at high temperatures, and in order to avoid this, it has been proposed to rationalize the magnetic layer, improve it by adding oxygen, and to apply rust preventives. Rust inhibitors are usually compounds that have a specific polar group that binds to ferromagnetic metal ions, and prevent rust from occurring by adsorbing them onto a ferromagnetic thin film. 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 unless special types are excluded, 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 that has excellent running stability and durability. be. That is, the present invention provides a rust preventive adsorption layer on the surface of a ferromagnetic metal thin film formed on a nonmagnetic substrate,
The present invention relates to a magnetic recording medium characterized in that a lubricant layer is provided on the adsorption layer. 1 to 3 schematically show examples of the structure of the magnetic recording medium of the present invention. In the figure, 1, 1',
1" is the substrate, 2, 2'2" is the ferromagnetic metal thin film, 3,
Numerals 3' and 3'' are rust preventive adsorption layers, 4, 4' and 4'' are lubricant layers, and 5 is a ferromagnetic metal oxide layer covering the surface of the oxygen-containing ferromagnetic metal thin film layer. In the example shown in FIG. 1, the lubricant 4 is uniformly adsorbed onto the rust preventive agent 3. In the example shown in FIG. 2, the lubricant 4' is aggregated and adsorbed in the form of islands on the rust preventive agent 3'. Figure 3 shows the first
Figure 2 shows an example from a microscopic perspective, which is obtained by obliquely depositing a ferromagnetic metal in the presence of a trace amount of oxygen gas. An example is shown in which a rust preventive adsorption layer 3'' is provided on a ferromagnetic metal thin film 2'' consisting of a columnar crystal structure whose surface is covered with an oxide layer, and a lubricant layer 4'' is present on the surface. As is clear from
In the magnetic recording medium of the present invention, the ferromagnetic metal thin film is covered with a rust preventive adsorption layer, so it has good corrosion resistance, and with the help of the lubricant layer on the surface, the coefficient of friction with the head is reduced, allowing repeated recording. The wear resistance of the magnetic recording medium surface during running is also improved. Also,
Surprisingly, it has been found that by interposing a rust preventive layer, the lubricant adsorption becomes stronger than when the lubricant is directly adsorbed onto the ferromagnetic metal thin film. Non-magnetic substrates include polyester film,
Plastic films such as polyimide films,
Metal plates such as aluminum plates and stainless steel plates, glass plates,
An inorganic board such as a ceramic board is used.
The surface properties of ferromagnetic metal thin film magnetic recording media are highly dependent on the surface shape of the substrate because the magnetic layer thickness is very small, about 0.1 to 0.5 μm. Therefore, JP-A-53-116115, JP-A-56-
Particularly desirable as the substrate for the present invention are substrates with finely controlled surface shapes as described in Japanese Patent Laid-Open Publication No. 16937 and Japanese Patent Application Laid-Open No. 57-37719. As a ferromagnetic metal thin film, iron, cobalt, nickel, or an alloy thereof can be deposited directly on the substrate by vacuum evaporation, ion plating, sputtering, etc., or it can be deposited as a thin film through a non-magnetic base thin film of aluminum, titanium, chromium, etc. Alternatively, a non-magnetic thin film inserted as an intermediate separator between a ferromagnetic thin film can be used. In particular, the ferromagnetic thin film and the underlying thin film contain oxygen (partially oxidizes the metal). ), it is particularly desirable to have improved adhesion strength with the substrate, corrosion resistance, magnetic properties, etc. Regarding the latter,
It is described in Japanese Patent Publication No. 56-23208, Japanese Patent Application Laid-open No. 42010-1980, Japanese Patent Application Publication No. 15014-1982, and Japanese Patent Application Publication No. 37719-1987. As the rust preventive agent that should form the rust preventive adsorption layer, for ferromagnetic metal thin films that do not particularly contain oxygen, rust preventive agents that are used for general metals can be used, examples of which include: Basic nitrogen compounds such as alkyl amines and fatty acid salts of alkyl amines, phosphorus compounds such as alkyl phosphates, alkyl thiophosphates, alkylhydrogen phosphates and phosphite esters, petroleum sulfonates, mahogany acid sulfonates, dinonylnaphthalene sulfonates sulfonates such as sorbitan monooleate, specific esters such as methyl esters of organic acids, metal soaps of petroleum acids and abietic acids, and specific carboxylic acid derivatives such as α-mercaptostearic acid. So-called volatile rust preventives such as dicyclohexylammonium nitrite, diisopropylammonium nitrite, and dichlorohexylamine carbamate can also be used. These examples can be found in the new edition of "Metal Surface Technology Benken", edited by the Metal Surface Technology Association (published in 1960, published by Nikkan Kogyo Shimbun).
Described on pages 1417-1439. In addition, the rust preventives used for general metals are not necessarily suitable for ferromagnetic metal thin films containing oxygen, and in fact, applying them actually accelerates corrosion. Therefore, it is important to use a rust preventive agent that is compatible with ferromagnetic thin films containing oxygen, in addition to known rust preventive agents. Rust inhibitors suitable for this purpose include divalent phenols,
There are 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, nitrone, and
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-trihydrobenzophenone, 2,4-dihydroxybenzophenone, 2,2',5,6'-tetrahydrobenzophenone, 2,3',4,4',6
-Hydroxybenzophenones such as bentahydroxybenzophenone, aminobenzophenones such as 4-aminobenzophenone and 4,4'-diaminobenzophenone, or benzophenones having two or more types of substituents, For example, it refers to 4-methoxy-2-hydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,6-dihydroxy-4-methoxybenzophenone, and the like. 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-tetr-butyl-
p-cresol, 4,4'-methylenebis, 2,6
-di-tert-butylphenol, 2,6-dimethyl-4-tert-butylphenol, 2-tert-amyl-4-methylphenol, 2-methyl-4,
6-di-tert-butylphenol, 2,4,6-
tri-tert-butylphenol, etc. Naphthols are α-naphthol, β-naphthol,
Pure naphthols such as 1,2-naphthalenediol, 1,4,5-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- This 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-hydroxyanthraquine, 1,2-dihydroxyanthraquinone, 12,
3-trihydroxyanthraquinone, 1,2,4
-trihydroxyanthraquinone, 1,2,5-
Hydroxyquinones such as trihydroxyanthraquinone, 1,2,6-trihydroxyanthraquinone, 1,2,7-trihydroxyanthraquinone, aminoquinones such as 2-amino-anthraquinone and 1,2-diaminoanthraquinone, 1-
Nitroquinones such as nitroanthraquinone and 1,5-dinitroanthraquinone, halogenoquinones such as 2,6-dichloro-P-benzoquinone, tetrachloro-P-benzoquinone, and tetrabromo-P-benzoquinone, or having two or more types of substituents Quinones, such as 2,5-dichloro-
3,6-dihydroxy-P-benzoquinone, 1-
It refers to methyl-2-hydroxy-1,4-naphthoquinone and the like. 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 2
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-nitrophenol, 2- Nitroso-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. Methods for forming an adsorption layer of a rust preventive agent on the surface of a ferromagnetic metal thin film include diluting the above rust preventive agent with a solvent and coating it thinly on the ferromagnetic metal thin film, or applying the rust preventive agent in air or inert gas. , or by vaporizing it in a vacuum and applying the vapor to the surface of a ferromagnetic metal. In this case, the rust inhibitor may be a single substance or a mixture of multiple types. In order to complete the adsorption of phenol, it is also possible to perform an appropriate heat treatment during or after the adsorption. It is desirable to remove excessively attached rust preventive by washing with a solvent.
Normally, rust preventives are strongly adsorbed to the surface of a ferromagnetic metal thin film in a chemically adsorbed or similar state, and therefore are not removed by solvents. This can be inferred from the fact that a sufficient rust prevention effect can be obtained even after solvent cleaning, and can also be determined by chemical shift measurement using X-ray photoelectron spectroscopy (ESCA). The lubricant layer is composed of the lubricant described below. Antistatic agents, antifungal agents, and the like may be added to the lubricant layer as necessary. As the lubricant, fatty acids, fatty acid esters, fatty acid amides, metal soaps, aliphatic alcohols, paraffins, silicones, fluorine-based surfactants, etc. can be used. Among these, some of them, such as fatty acids and fluorine-based surfactants, have antirust effects on ferromagnetic metal thin films, but by making them exist on the above-mentioned rust preventive adsorption layer, In the present invention, it is appropriate to use them as lubricants because the effect is further improved compared to when they are used alone. 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, oleic acid amide, linoleic acid amide, methylene bisstearic acid amide, ethylene bis stearic acid amide, etc. Can be used. Metallic soaps include zinc, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, etc.
Salts with lead, nickel, cobalt, iron, aluminum, magnesium, strontium, copper, etc., salts with sulfonic acids such as lauryl, palmityl, myristyl, stearylbehenyl, oleyl, linole, linolenic, etc. and the various metals listed above, etc. 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 phenol 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. 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 evaporation or the like, a lubricant layer may be formed over the entire surface of the columnar crystal as shown in FIG. The effects of the present invention can be obtained even in a state where is locally precipitated on the surface. Next, examples of the present invention will be described. A polyester film with a thickness of 10 μm and a corrugated protrusion with a surface grain size Rmax = approximately 300 Å is placed along the circumference of a cylindrical can, and oxygen gas is applied at a flow rate of 0.3/min at a vacuum level of 5 × 10 ^-5 Torr. CoNi alloy (Ni content
20wt%) was continuously obliquely deposited (cutting the low incident angle component below 30°), and a 1000 Å thick oxygen-containing CoNi ferromagnetic thin film was formed on the film (sample A), and a sample was deposited under vacuum under similar conditions as above. degree 5×
A CoNi ferromagnetic thin film containing no oxygen was prepared by vapor deposition at 10 ^-6 Torr without introducing oxygen gas (sample B). As a result of measuring oxygen in the film mainly using Auger electron spectroscopy, it was found that the average amount of oxygen in the film of sample A was 10% in terms of atomic ratio (O/Co + Ni x 100) to Co and Ni, and that of sample B was 10%. It was less than 1%. Various rust preventive agents are dissolved in water, alcohol, acetone, ethyl acetate, toluene, etc. and applied to the surface of these samples, and then washed with these solvents and dried to form an adsorption layer of the rust preventive agent on the sample surface. formed. A lubricant layer was formed on the surface by diluting various lubricants with a solvent and coating and drying. If a suitable solvent does not exist, the sample surface is exposed to lubricant vapor by heating in vacuum, air, or inert gas to form a lubricant layer (applying amount is 10 to 10%). 100
It was adjusted to be mg/ ^m2 . ). Then, these samples are slit to a predetermined width,
It was made into magnetic tape. These tape samples were heated to 50°C.
The samples were left in a 90% RH atmosphere, during which they were taken out every 3 days for samples A and every 1 day for samples B, and recorded and played back on a video deck to check for head clogging. The state of rust formation was investigated by microscopic observation. The results are shown in the table below.

【table】

[Table] Although the above examples relate to CoNi-based magnetic thin films, this effect was similar in Co thin films, Fe-Ni thin films, Fe-Co thin films, and the like. Additionally, ferromagnetic thin films containing oxygen are more effective than pure metal thin films;
It is significantly obtained with an oxygen content of 3 to 45%. As is clear from the above, the magnetic recording medium of the present invention improves the adhesion strength with the non-magnetic substrate by providing a magnetic layer made of a ferromagnetic metal thin film containing oxygen.
Corrosion resistance and magnetic properties can be improved. In addition, by providing an adsorption layer of a rust preventive agent consisting of at least one of divalent phenols, diallyl ketones, alkylphenols, naphthols, quinones, nitroso compounds, and oxime compounds, ferromagnetic metals containing oxygen can be Furthermore, by forming a lubricant layer on the rust preventive adsorption layer, the function of the lubricant layer is maximized and synergistic prevention is achieved. It improves the rust effect and prevents clogging during recording playback after storage in a high-humidity environment, and has great practical value.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are sectional views of magnetic recording media according to embodiments of the present invention. 1, 1', 1''... substrate, 2, 2', 2''... ferromagnetic metal thin film, 3, 3', 3''... rust preventive adsorption layer,
4, 4', 4''...Lubricant layer, 5...Oxide layer.

Claims (1)

[Claims] 1 A magnetic recording medium in which a ferromagnetic metal thin film containing oxygen is formed on a non-magnetic substrate, wherein divalent phenols, diaryneketones,
A magnetic recording medium characterized in that an adsorption layer of a rust preventive agent consisting of at least one of alkyphenols, naphthols, quinones, nitroso compounds, and oxime compounds is formed, and a lubricant layer is formed on the adsorption layer. .