JPH0135406B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention belongs to the field of magnetic recording using electromagnetic conversion, such as magnetic tapes and magnetic disks. Structure of conventional examples and their problems Fe, Ni, Ni,
A magnetic recording medium on which a ferromagnetic metal thin film mainly composed of Co or an alloy thereof is formed is suitable for high-density recording such as video signal recording. Because of its small size of μm, if it is left in high humidity environments, especially in environments where there are large temperature changes and condensation, the surface tends to corrode, and if the corrosion progresses to a certain extent, it will affect the electromagnetic conversion characteristics. Deteriorates practical properties such as wear resistance. Attempts have been made to suppress this corrosion with rust preventive agents, and known rust preventive agents for bulk metals such as Fe, Co, and Ni can be used as such rust preventive agents. Examples of these include alkylamines, basic nitrogen compounds such as fatty acid salts of alkylamines, phosphorus compounds such as alkyl phosphates, alkyl thiophosphates, alkylhydrogen phosphates and phosphite esters, petroleum sulfonates, mahogany acids, etc. Sulfonates, sulfonates such as dinonylnaphthalene sulfonate, sorbitan monooleate, specific esters such as methyl esters of organic acids, petroleum acids, metal soaps of abietic acid, and specific carboxylic acid derivatives such as α-mercaptostearic acid. In addition, there are so-called volatile rust inhibitors such as dicyclohexylammonium nitrite, diisopropylammonium nitrite, and cyclohexylamine carbamate. Regarding these rust preventive agents for bulk metals, for example, see the new edition of "Metal Surface Technology Handbook," edited by the Metal Surface Technology Association (published in 1960, publisher: Nikkan Kogyo Shimbun).
Described on pages 1417-1439. A ferromagnetic metal thin film that contains oxygen by introducing a small amount of oxygen gas into the vacuum system when forming a ferromagnetic metal thin film has a higher coercive force than a film that does not contain oxygen, and the bond between the substrate and the film is improved. Adhesive strength is also improved,
Corrosion resistance is also greatly improved, but corrosion resistance under harsh environments is still not at a sufficient level, and the application of rust inhibitors is desired for this purpose as well. However, the above-mentioned rust inhibitors suitable for ferromagnetic metal thin films that do not contain oxygen have almost no rust-preventing effect on oxygen-containing ferromagnetic metal thin films, and may even accelerate corrosion. One thing became clear. Conventional bulk metal rust inhibitors act directly on the metal to stabilize its surface condition (this is clearly stated, for example, in the following documents: G. Tranbanelli & V. Carassiti:
“Advances in Corrosion Science and
Technology. “Vol.1, p.147 (PLENUM Press.
New York.1970)) However, since the surface of a ferromagnetic metal thin film containing oxygen is covered with an oxidized layer of ferromagnetic metal, when such a rust inhibitor is used, the rust inhibitor penetrates inside the oxidized layer. It is thought that the oxide layer passes through and acts on the metal inside, causing the oxide layer to no longer function as an original protective layer. Therefore, it has become necessary to find a new rust preventive agent for ferromagnetic metal thin films containing oxygen. As mentioned above, ferromagnetic metal thin film magnetic recording media can dramatically improve the recording density compared to conventional coated magnetic recording media, but in order to achieve this high density, magnetic It is necessary to reduce the spacing loss as much as possible by reducing the head gap and smoothing the surface of the magnetic recording medium. The specific spacing value is
The thickness 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 a magnetic recording medium, it is essentially difficult to significantly reduce the contact area between the head and the medium.
It is difficult to avoid a tendency for the coefficient of friction to increase. The rust preventive agent used in the present invention is a compound having a specific polar group that binds to a ferromagnetic metal ion, its oxide ion, or its hydroxide ion. Although it prevents this from occurring, it has become clear that it does not have much of an effect on improving head touch and runnability, and has the drawback that excessive adhesion can cause head clogging. 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. OBJECTS OF THE INVENTION The present invention aims to further improve the corrosion resistance of a magnetic recording medium that uses a ferromagnetic metal thin film containing oxygen as a magnetic layer, as well as to improve running properties and durability. Structure of the Invention The present invention provides a magnetic recording medium in which a ferromagnetic metal thin film containing oxygen is formed on a non-magnetic substrate, in which the ionized ferromagnetic metal is hydrated by acting on the ionized ferromagnetic metal around the ferromagnetic metal thin film. The present invention is characterized by the presence of a compound that suppresses the ferromagnetic film, and is further characterized by the presence of a lubricant on the ferromagnetic film. DESCRIPTION OF THE EMBODIMENTS First, as the non-magnetic substrate, a film or sheet made of plastic such as polyester, polyamide or polyimide, a metal plate made of metal such as aluminum or stainless steel, a ceramic plate, a glass plate, etc. are 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 and JP-A-57-37719
A substrate with a finely controlled surface shape as described in the above publication is particularly desirable as a substrate for the present invention. Regarding ferromagnetic metal thin films containing oxygen,
They are described in JP-A-56-23208, JP-A-53-42010, JP-A-56-15014, JP-A-57-37719, and the like. A ferromagnetic thin film obtained by continuous oblique deposition in a vacuum containing oxygen gas is composed of an aggregate of fine columnar crystals, and the surface of each columnar crystal is covered with an oxide layer of the ferromagnetic metal that makes up the crystal. There is. This oxide layer is thin, about 100 to 200 Å at most, and contains many defects such as crystal structure defects and hydrates, and when the thin film is placed in high humidity, these defects are Magnetic metal ions, ions of their oxides, or ions of their hydroxides are easily hydrated to form hydrous oxides of ferromagnetic metals, that is, rust. As a result of studies conducted by the present inventors, compounds that act on these ionized ferromagnetic metals (i.e., ferromagnetic metal ions, ions of their oxides or hydroxides) and suppress the hydration of these ions are found to be oxygen-containing compounds. The conclusion was that it is the best rust preventive agent for ferromagnetic metal thin films. In the following text, the above compounds will be referred to as rust preventive agents. Rust inhibitors include, for example, divalent phenols, diallyl ketones, alkylphenols, naphthols, quinones, nitroso compounds, oxime compounds, etc. These are shown in more detail as follows: Become. 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 derivatives thereof, such as benzophenone, 4-methylbenzophenone, 3-methylbenzophenone,
Alkyl substituted products such as 3,4-dimethylbenzophenone, 4,4'-dimethylbenzophenone, 4-ethylbenzophenone, 4-hydroxybenzophenone, 4,4'-dihydroxybenzophenone,
2,3,4-trihydrobenzophenone, 2,4
-dihydroxybenzophenone, 2,2',5,
6′-tetrahydrobenzophenone, 2,3′,4,
Hydroxybenzophenones such as 4',6-bentahydroxybenzophenone, aminobenzophenones such as 4-aminobenzophenone and 4,4'-diaminobenzophenone, or two or more substituents. benzophenones, such as 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-
Di-methyl-4-tert-butylphenol, 2-
tert-aluminum-4-methylphenol, 2-methyl-4,6-di-tert-butylphenol, 2,
4,6-tri-tert-butylphenol, etc. Naphthols include α-naphthol, β-naphthol, 1,2-naphthalenediol, 1,4,
Pure naphthols such as 5-naphthalenetriol, 1,2,5,8-naphthalenetetraol and nitro-, nitroso-, amino-, 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. , methyl-P-benzoquinone, 2,3-dimethyl-P-benzoquinone, 2-methyl-1,4-naphthoquinone, 2-methylanthraquinone, etc., 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,
Halogen quinones 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-nitroso- 1-naphthol-4-
It refers to 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. These anti-corrosion agents exert their effects by being present at least on the surface of the ferromagnetic thin film, if possible inside, or in contact with the interface with the substrate on which the ferromagnetic thin film is formed. urge The appropriate amount is about 0.5 to 500 mg per m ² of magnetic recording medium. Specifically, the presence of a rust preventive agent is carried out by itself or in a mixture with a substance capable of forming a film such as a polymer compound, diluted with a solvent if necessary, and applied to the surface of a ferromagnetic thin film. how to apply it,
A method in which rust preventive vapor is applied to the surface of the ferromagnetic thin film.Furthermore, if the magnetic recording medium is in the form of a tape, it is placed on the back side and transferred to the surface of the ferromagnetic thin film when the tape is rolled up. Well-known means such as a method for doing this can be used. Also,
By forming a ferromagnetic metal thin film on a non-magnetic substrate on which a rust preventive agent has been applied in advance, the rust preventive agent is applied especially to the side of the ferromagnetic metal thin film that is in contact with the substrate.・It is possible to make ・exist. As a method for manufacturing a substrate containing a rust preventive agent, for example, at least the surface of the non-magnetic substrate is made finely porous by etching, etc., and the rust preventive agent is added inside the non-magnetic substrate.
For plastic film substrates, a method in which a rust preventive agent is added to the substrate raw material or a surface shape imparting agent during film formation, or a method in which the substrate is immersed in a solution of a rust preventive agent. Rust preventive agent...
There are methods such as infiltrating the substrate into the substrate. The rust preventive agent may exist uniformly within the nonmagnetic substrate, may be unevenly distributed near the surface thereof, or may be segregated in the form of fine particles. However, it is desirable that it exists at least on the magnetic layer forming surface. The appropriate rust preventive content of the nonmagnetic substrate is 0.001 to 10% by weight, more preferably 0.01 to 1% by weight, at least near the surface on the side where the magnetic layer is formed (that is, within a depth of 1000 Å from the surface). Inside, it may be equal to or lower than near the surface. The rust preventive agent may be a single material or a mixture of multiple materials as in the example above.In order to improve the effect of the rust preventive agent on the ferromagnetic metal thin film, the rust preventive agent ...It is also possible to heat-treat the ferromagnetic metal thin film after application. Furthermore, if an excessive amount of the rust preventive agent adheres to the ferromagnetic metal thin film, it can be removed by cleaning the surface of the thin film with a solvent that selectively dissolves the rust preventive agent.
Normally, rust preventive agents strongly adsorb to specific locations on the surface of ferromagnetic metal thin films in a state that is chemically adsorbed or close to it.
It will not be removed by solvent cleaning. 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 photometry (ESCA). As mentioned in the section on conventional examples, the rust preventive used in the present invention does not have a significant effect on improving the coefficient of friction between the magnetic recording medium and the magnetic head, rotating cylinder, etc. If high lubricity is required, combinations with various lubricants must be considered. Specific means for this include, for example: (1) A lubricant layer is formed on (outside) a ferromagnetic metal thin film around which a rust preventive agent is present. (2) A ferromagnetic metal thin film with a rust preventive agent surrounding it on one side of a flexible long non-magnetic substrate,
A lubricant layer or a lubricant-containing resin layer may be formed on the other side. FIGS. 1 to 3 schematically show examples of the structure of the magnetic recording medium described in (1) above. In the figure, 1, 1',
1″ is the substrate, 2, 2′, 2″ is the ferromagnetic metal thin film, 3,
3' and 3'' are adsorption layers for rust preventive agents, 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. be. In the example shown in FIG. 1, the lubricant 4 is uniformly adsorbed onto the rust preventive agent 3. In the example shown in Figure 2, the lubricant 4' is placed on top of the rust preventive agent 3'.
is aggregated and adsorbed in the form of islands. 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. This figure shows an example in which a rust preventive adsorption layer 3'' is present on a ferromagnetic metal thin film 2'' having a columnar crystal structure whose surface is coated 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 adsorption of the lubricant becomes stronger than when the lubricant is directly adsorbed onto the ferromagnetic metal thin film. The lubricant layer is composed of the lubricant described below. Antistatic agents, antifungal agents, and the like can 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. Some of these, such as fatty acids and fluorine-based surfactants, have antirust effects on ferromagnetic metal thin films; however, by making them exist on the 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,
Valmitic 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 lauryl, palmityl, myristyl, stearylbehenyl, oleyl, linole, linolenic acid sulfonic acids 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 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. 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. In addition, in each of the above examples, a rust preventive agent is included in the lubricant layer.
It is also possible to mix and add a rust preventive agent, and by making an excessive rust preventive agent exist on the ferromagnetic metal thin film in this way, it is possible to further improve the corrosion resistance. Next, to explain the magnetic recording medium of (2) above, in this case, the lubricant layer is formed by applying each of the above lubricants alone or a mixture thereof directly onto the surface of the non-magnetic substrate, or onto the surface of the non-magnetic substrate in advance. This is done by depositing on the formed backcoat layer. Specifically, this is done by applying a thin layer of lubricant diluted with a solvent or by applying lubricant vapor to the surface. In this case, in the lubricant,
It is also possible to add antistatic agents, antifouling agents, rust preventive agents present on the magnetic surface, etc. The amount of lubricant deposited is 0.5 to 500 per ^m2 of magnetic recording medium.
mg, preferably 5 to 200 mg. Further, as another method of forming a lubricant layer, a method of mixing a lubricant into the back coat to form a lubricant layer can also be adopted. Specifically, the above-mentioned materials are added to a solution of a resin such as vinyl chloride, ester, urethane, or epoxy, in which fine powders of carbon black, graphite, molybdenum disulfide, calcium carbonate, silica, alumina, etc. are dispersed. A solution in which a lubricant is dissolved or dispersed is applied to the surface of a nonmagnetic substrate to form a back coat containing the lubricant. In this case, the thickness of the coating film obtained is 0.01~
0.5 μm, lubricant content in the coating film is 0.1 to 50% by volume
A range of is appropriate. It is also possible to add to this back coat an antistatic agent, an antifouling agent, a rust preventive agent adsorbed on the magnetic surface, etc. If a rust preventive agent is added to the lubricant layer, when a magnetic recording medium is wound up and the two sides come into contact, the rust preventive agent will be transferred to the magnetic surface together with the lubricant, and this will prevent the magnetic properties during actual use. It can be newly adsorbed to damaged areas such as abrasion of the layer surface or cracks generated in the magnetic layer, thereby preventing deterioration of the corrosion resistance of that area. For the same purpose, it is also possible to leave an excess amount of rust preventive agent on the surface of the magnetic layer that is not adsorbed on the adsorption layer, but if this amount is too large, it may cause clogging of the head. Therefore, this amount is the maximum per ^1m2 of magnetic recording medium.
The limit is 100 mg, and 5 to 50 mg is desirable. That is, within this limit, clogging can be prevented by the effect of transferring the lubricant to the magnetic surface, and this is one of the effects of the present invention. For the purpose of perfecting the transfer of the lubricant onto the magnetic surface, the magnetic recording medium can be heat-treated in its wound state immediately after manufacturing, if necessary. The conditions in this case are, for example, 30 to 60°C for 1 to 50 hours. Next, a more specific example will be explained. Example 1 A 10 μm thick polyester film was placed along the circumferential surface of a cylindrical can, and a CoNi alloy (CoNi alloy) was melted by electron beam heating by introducing oxygen gas at a rate of 0.3/2 in a vacuum of 5 × ^{10 -5} Torr. Ni content 20wt
%) was continuously obliquely deposited (cutting the low incident angle component below 30°) to form an oxygen-containing CoNi ferromagnetic thin film with a thickness of 1000 Å on the film (Sample A).
And under similar conditions as above, the degree of vacuum is 5×10 ^-6 Torr,
CoNi that does not contain oxygen without introducing oxygen gas
A sample (sample B) on which a ferromagnetic thin film was formed was prepared. As a result of measuring the amount of 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×100) to Co and Ni, and that of Sample B. It was less than 1%.
Various rust preventive agents were applied to the surfaces of these samples by dissolving water, ethyl alcohol, acetone, toluene, etc., and dried (the amount of application was adjusted to 10 to 100 mg/ ^m2 ), and then heated at 50°C. The specimens were left in a 90% RH atmosphere, during which time they were periodically taken out and observed under a microscope to examine the state of rust formation. The results are shown in Tables 1 to 6. As is clear from these tables, rust inhibitors...
had a large rust-preventing effect on CoNi thin films containing oxygen. This effect is similar for CoNi thin films with an oxygen content of 3 to 45% (Ni 10 to 55wt%);
Similar results were observed in Fe-Ni thin films, Fe-Co thin films, etc.

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[Table] Example 2 A polyester film with a thickness of 10 μm and having waveform protrusions on the surface with a surface grain size Rmax = approximately 300 Å was placed along the circumferential surface of a cylindrical can, and oxygen gas was blown at a vacuum level of 5 × 10 ^-5 Torr. CoNi alloy (Ni content:
20 wt%) 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 coat the surface of the sample with rust preventive agents. An adsorption layer was formed. A lubricant layer was formed on the surface by diluting various lubricants with a solvent and coating and drying. In addition, if a suitable solvent does not exist, a lubricant layer is formed by heating the sample in vacuum, air, or inert gas to expose the sample surface to lubricant vapor (the amount applied is 10 to 10%).
The concentration was adjusted to 100 mg/m ² . ). After that, 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 Table 7 below.

【table】

[Table] Example 3 Same sample A and sample B used in Example 2
Various rust preventive agents were dissolved in ethyl alcohol, acetone, ethyl acetate, toluene, etc. and applied to the surface using a .coating agent and dried to form an adsorption layer of the rust preventive agent. The coating amount was adjusted to be around 10 mg/m ² . Also, the back side (polyester film side surface)
Next, various lubricants were dissolved in the above-mentioned solvents, applied and dried to form a lubricant layer. Application amount is 10-100
It was adjusted to be mg/ ^m2 . Thereafter, these samples were kept in a rolled form at 30° C. for 10 hours, and then slit into a predetermined width to form magnetic tapes. These tape samples were left in an atmosphere of 50°C and 90% RH, during which they were taken out every 3 days for sample A and every 1 day for sample B, and recorded and played back on a video deck to check for clogging. The state of rust occurrence was investigated by observing the surface of the layer side under a microscope. The results are shown in Table 8.

【table】

[Table] Although each of the above examples relates to a CoNi-based magnetic thin film, this effect also applies to Co thin films, Fe-Ni magnetic thin films, etc.
It was similar in thin films, Fe-Co thin films, etc.
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%. Effects of the Invention As is clear from the above, the magnetic recording medium of the present invention has improved corrosion resistance, runnability, and overall durability including head clogging, and its practical value is extremely large. be.

[Brief explanation of drawings]

FIG. 1, FIG. 2, and FIG. 3 are sectional views each showing a configuration example of a magnetic recording medium according to the present invention. 1, 1', 1''...substrate, 2, 2', 2''...ferromagnetic metal thin film, 3, 3', 3''...adsorption layer, 4, 4',
4″...Lubricant layer, 5...Oxide layer.

Claims (1)

[Claims] 1. A ferromagnetic metal thin film containing 3 to 45% oxygen atoms in atomic ratio to ferromagnetic metal is formed on a non-magnetic substrate, and divalent phenols are added around the ferromagnetic metal thin film. , diallyl ketones, alkylphenols, naphthols, quinones, nitroso compounds, and oximes.
1. A magnetic recording medium, characterized in that a compound is present which acts on an ionized ferromagnetic metal and suppresses hydration of the ion, and further a lubricant is present on the ferromagnetic metal thin film. 2 At least one selected from divalent phenols, diallyl ketones, alkylphenols, naphthols, quinones, nitroso compounds, and oximes on one side of the flexible long nonmagnetic substrate.
A ferromagnetic metal thin film containing 3 to 45% oxygen in terms of atomic ratio to the ferromagnetic metal is made by surrounding the ionized ferromagnetic metal with a compound that acts on the ionized ferromagnetic metal and suppresses the hydration of the ion. A magnetic recording medium comprising a lubricant content formed on the other surface of the substrate.