JPH0150969B2 - - 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 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 blating are different from conventional coated magnetic recording media. It is possible to dramatically improve the recording density compared to recording media, but in order to achieve this high 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 from occurring by adsorbing them onto a ferromagnetic thin film. It has become clear that there is very little of it, and that excessive adhesion can cause 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 nonmagnetic thin film layer containing a rust preventive agent, a ferromagnetic metal thin film layer, and a lubricant layer are sequentially provided on a nonmagnetic substrate. 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 non-stainless plates such as glass plates and ceramic plates. The surface properties of ferromagnetic metal thin film magnetic recording media are determined by the thickness of the magnetic layer being 0.1~
Since it is extremely small at around 0.5 μm, it is highly dependent on the surface shape of the substrate. Therefore, for example, in the case of a polyester film, it is possible to limit the size of fine particles based on polymerization catalyst residue, added fine particles, etc., or to form a thin resin film layer mainly composed of various polymers on the surface and specify its shape. Various types of films have been proposed in which the surface shape of the film is finely controlled by changing the surface shape of the film. Taking the example of the above-mentioned polyester film as an example, the present invention involves adding a rust preventive agent to the latter resin-based thin film layer mainly composed of various polymers, or adding a new anti-rust agent to the surface of the film having the resin-based thin film layer. The present invention relates to a magnetic recording medium in which a substrate film on which a nonmagnetic thin film layer containing a rust preventive agent is formed is prepared, and a ferromagnetic metal thin film layer and a lubricant layer are sequentially formed thereon. The non-magnetic thin film layer containing a rust preventive agent may be a resin thin film containing various rust preventive agents described below, a porous thin film containing a rust preventive agent in its pores (for example, a porous non-magnetic metal plating film, a porous thin film containing a rust preventive agent, etc. In this case, the antirust agent may be present uniformly within the nonmagnetic substrate, or may be unevenly distributed in the form of 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 blating, sputtering, etc.
A thin film formed through a non-magnetic base thin film such as titanium or chromium, or a thin film formed by inserting the above-mentioned non-magnetic thin film as an intermediate separator between a ferromagnetic thin film can be used. By containing oxygen in the thin film (partially oxidizing the metal), the adhesion strength and corrosion resistance to the substrate can be improved.
A material with improved magnetic properties, etc. is required. 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. Furthermore, the rust preventives used for general metals are not necessarily suitable for ferromagnetic metal thin films containing oxygen, and in fact, applying these preventives 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. This purpose includes 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-amyl-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, 1,4,5
-Pure naphthols such as naphthalenetriol, 1,2,5,8-naphthalenetetraol,
Nitro, nitroso, and halogeno-substituted naphthols,
For example, 1-chloro-2-naphthol, 2,4
-dichloro-1-naphthol, 1-nitro-2-
It refers to naphthol, 1,6-dinitro-2-naphthol, 1-nitroso-2-naphthol, 2-nitroso-1-naphthol, 1-amino-2-naphthol, and the like. 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 diphenocanone. , 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 tetrafluoro-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 disodium 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-sulfonic acid, 5-nitroso-8-quinolinol, etc. It refers to The oxime compound refers to benzyloxime, glyoxime, benzaldoxime, benzamide oxime, α-benzoin oxime, acetophenonexime, benzophenonexime, dimethylglyoxime, salicylaldoxime, and the like. The rust preventive content in the non-magnetic thin film layer is as follows:
A suitable amount is 0.001 to 50% by weight, more preferably 0.01 to 10% by weight, and a suitable thickness of the nonmagnetic thin film layer is 50 Å to 10,000 Å. The lubricant layer is mainly composed of the lubricant described below, and binders made of various polymer materials, the above-mentioned rust preventive agents, antistatic agents, antifungal agents, etc. can also be added 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. 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, lauric acid, myristic acid, balmitic acid, stearic acid, behenic acid, olefinic 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 fatty acid 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 rust preventive adsorption layer on the surface of the ferromagnetic metal thin film, the above lubricant or a mixture of various additives may be diluted with a solvent and applied thinly onto the ferromagnetic metal thin film. This can be done by applying steam to the surface. 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 non-magnetic thin film layer protects 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 at the crystal interface, the entire crystal structure is protected by the rust preventive agent, and the corrosion resistance of the magnetic layer is improved. In addition, many rust inhibitors themselves generally have poor lubricity, and if they are applied directly to the surface of the magnetic layer and are present in excess, they may cause head clogging when using media. There is no excessive rust preventive agent on the surface of the medium, and head clogging does not occur. 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 thin layer of copolymerized polyester containing colloidal silica (0.1 μm thick, surface roughness
These films were placed along the circumference of a cylindrical can and oxygen gas was applied at a vacuum level of 5 x 10 ^-5 Torr.
CoNi alloy (Ni content 20wt%) was introduced at a flow rate of 0.3/min and melted by electron beam heating, and was continuously deposited obliquely (cutting the low incident angle component by 30° or less).
An oxygen-containing CoNi ferromagnetic thin film with a thickness of 1000 Å was formed into a film (sample A), and oxygen obtained by vapor deposition with a vacuum degree of 5 × 10 ^-6 Torr and oxygen gas introduced under the same conditions as above was used. A sample (Sample B) was prepared in which a CoNi ferromagnetic thin film was formed without containing CoNi. In addition, as comparative samples, we prepared samples in which a ferromagnetic thin film was formed under the same conditions as above on a polyester film on which a nonmagnetic thin film layer was formed that did not contain the rust preventive, and a sample in which oxygen was added was prepared. A', and the sample that did not contain oxygen was designated as sample B'. As a result of measuring oxygen in the film mainly using Auger electron spectroscopy, the average amount of oxygen in the film of samples A and A' was 10% in terms of atomic ratio (O/Co + Ni x 100) to Co and Ni. For B, it 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 left in an atmosphere of 50°C and 90% RH.
During this time, sample A was taken out every three days, and sample B was recorded and played back every day using a video deck to check for clogging, and the surface of the magnetic layer side was observed under a microscope to check for rust. The results are shown in the attached table.

【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. A resin containing 0.001 to 50% by weight of a rust inhibitor selected from divalent phenols, diallyl ketones, alkylphenols, naphthols, quinones, nitrone compounds, and oxime compounds on a nonmagnetic substrate. A ferromagnetic thin film or a porous nonmagnetic thin film containing 0.01 to 50% by weight of the above-mentioned rust inhibitor is provided in the pores, and a ferromagnetic film containing 3 to 45% of oxygen atoms in terms of atomic ratio to the ferromagnetic metal is placed on top of the porous nonmagnetic thin film containing 0.01 to 50% by weight of the rust preventive. A magnetic recording medium comprising a magnetic metal thin film layer and a lubricant layer thereon.