JPS6182322A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent the generation of rust and to decrease the change of the magnetic characteristics such as coercive force with time of a thin ferromagnetic metallic film type magnetic recording medium by sticking a rust preventive agent consisting essentially of a heterocyclic compd. contg. sulfur atoms to the thin ferromagnetic metallic film said medium. CONSTITUTION:The thin ferromagnetic metallic film consisting of an Fe-Ni alloy Co-Ni alloy, etc. is formed on a nonmagnetic base consisting of a polyethylene terephthalate film, etc. The rust preventive agent consisting essentially of the heterocyclic compd. contg. sulfur atoms is stuck on the thin ferromagnetic metallic film, by which the intended magnetic recording medium is obtd. The embodiment of the heterocyclic compd. is exemplified by sulfolan, 3-hydroxy sulfolene, rhodanine, thiazoline-4-carboxylic acid, etc. The adequate amt. of the rust preventive agent is about 0.5-100mg for each 1m<2> of the magnetic recording medium and a method for dissolving the rust preventive agent in a solvent and coating the soln. thereof on the thin ferromagnetic metallic film is used as the method for sticking the rust preventive agent on said film.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to magnetic recording of a so-called ferromagnetic metal thin film type in which a ferromagnetic metal thin film is formed on a nonmagnetic support by vapor deposition, ion blating, sputtering, etc. It's about the medium.

[Conventional technology]

Conventionally, as a magnetic recording medium, r
-Fe20a, 1-Fe20a containing Co,
Fe5O4,r-Fe containing Pe504, Co
20a and FeaO+ Bertolide compounds, CO-containing Bertolide compounds, oxide magnetic powders such as Co, or Fe.

By applying and drying a magnetic paint in which a powder magnetic material such as an alloy magnetic powder mainly composed of Co, Ni, etc. is dispersed in an organic binder such as vinyl chloride-vinyl acetate copolymer, polyester resin, polyurethane resin, etc. The resulting coated magnetic recording medium is widely used.

In recent years, with the increasing demand for high-density magnetic recording (metal magnetic thin films made of ferromagnetic metals are deposited on magnetic supports using techniques such as vacuum evaporation, sputtering, ion blating, and plating), Directly deposited ferromagnetic metal thin film magnetic recording media are attracting attention.These ferromagnetic metal thin film magnetic recording media not only have a large coercive force Hc and a large residual magnetic flux density Br, but also have extremely thick magnetic layers. Since it can be made thinner, the thickness loss during recording demagnetization and reproduction is extremely small, and since there is no need to mix an organic binder, which is a non-magnetic material, into the magnetic layer, it is possible to increase the packing density of the magnetic material. It has many advantages in terms of magnetic properties.

However, since the magnetic layer of ferromagnetic metal thin film magnetic recording media is made of metal, the surface of the magnetic layer tends to corrode during storage, especially when left in high temperature or high humidity conditions, resulting in a decrease in the amount of saturation magnetization. There has been a problem that the magnetic properties of these drugs deteriorate when administered orally.

Therefore, attempts have been made to improve the corrosion resistance of magnetic recording media by depositing a rust preventive agent on the ferromagnetic metal thin film.

For example, dihydric phenols are used as rust preventive agents (Japanese Patent Application Laid-open No. 57-152517), diallyl ketones are used (Japanese Patent Application Laid-Open No. 57-152518), and alkylphenols are used (Japanese Patent Laid-Open No. 57-152519). , the use of naphthols (Japanese Unexamined Patent Publication No. 57-152520), etc. are disclosed in the above publication.

[Problems to be Solved by the Invention] The present invention provides a ferromagnetic metal thin film type magnetic recording medium in which almost no rust occurs on the surface of the magnetic layer even under high temperature or high humidity conditions, and little change in magnetic properties occurs. The present invention aims to solve the above-mentioned problems by using a novel anticorrosion agent.

[Means for solving problems]

That is, in the magnetic recording medium according to the present invention, a ferromagnetic metal thin film is formed on a nonmagnetic support, and a rust preventive agent containing a sulfur atom-containing heterocyclic compound as a main component is attached to the ferromagnetic metal thin film. It is characterized by this.

In the present invention, the heterocyclic compound containing a sulfur atom used as a rust preventive agent includes sulfolane, 3-hydroxysulfolane, 3-methylsulfolane, sulfolene, 3-
Hydroxysulfolene, 3-methylsulfolene, rhodanine, 3-aminorotanine, thiazoline-4-carboxylic acid, 4H-1,4-thiazine, biotin, 3,6-thioxanthine diamine, 3,6-thioxanthine diamine -10,10-dioxide and the like.

The above-mentioned rust preventive agent exhibits its effect by being present at least on the surface of the ferromagnetic metal thin film, if possible inside, or in contact with the interface with the base on which the ferromagnetic metal thin film is formed. The appropriate amount is about 0.5 to 100 m7 per magnetic recording medium.

The above-mentioned rust preventive can be applied to the ferromagnetic metal thin film by diluting it in an appropriate solvent and applying it to the ferromagnetic metal thin film, or by applying the vapor of the rust preventive to the ferromagnetic metal thin film. It is possible to use methods such as a method of applying

Further, a normal lubricant may be used in combination with the rust preventive agent. Examples of the above-mentioned solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, alcohols such as methanol, ethanol, furopanol, and butanol, methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and acetic acid glycol monoethyl ether. esters such as ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, tetrahydrofuran, dioxane, etc., aromatic hydrocarbons such as benzene, toluene, xylene, aliphatic hydrocarbons such as hexane, heptane, methylene chloride, ethylene, etc. Chloride, carbon tetrachloride, chloroform,
Chlorinated hydrocarbons such as ethylene chlorohydrin and dichlorobenzene, trichlorofluoromethane, dichlorodifluoromethane, chlorotrifluoromethane, chlorodifluoromethane, 1,1.2-trichloro-1,2゜2-trifluoroethylene, 3 Examples include fluorohydrocarbons such as -dichlorotetrafluoroethylene, water, and mixed solvents thereof.

Further, as the lubricant, fatty acids, fatty acid esters, trifatty acid oxides, metal soaps, aliphatic alcohols, paraffins, silicones, fluorine surfactants, etc. can be used.

As the fatty acid, those having 12 or more carbon atoms such as lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, and lilunic acid can be used.

As the fatty acid ester, ethyl stearate, butyl stearate, amyl stearate, stearic acid monoglyceride, oleic acid monoglyceride, 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 bisstearamide, etc. can be used.

Examples of metal soaps include Zn and Pb such as lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid, and linuric acid.

Tono salts such as Ni, Co, Fe, ACMg, Sr, Cu, etc.
Salts of sulfonic acids such as lauryl, palmityl, myristyl, stearyl, behenyl, oleyl, linole, and linole with the above metals can be used.

As the aliphatic alcohol, cetyl alcohol, stearyl alcohol, etc. can be used.

As the paraffin, saturated hydrocarbons such as n-nonadecane, n-tridecane, and n-tocosan 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, fatty acid amides, etc. can be used.

As the fluorine-based surfactant, perfluoroalkylcarboxylic acid and perfluoroalkylsulfonic acid and Na,
Tono salts such as Mg, Zn, ACFe, Co, and Ni, perfluoroalkyl phosphates, perfluoroalkylvequins, perfluoroalkyltrimethylammonium salts, perfluoroethylene oxide, perfluoroalkyl aliphatic esters, and the like can be used.

Materials for the non-magnetic support include polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, cellulose triacetate,
Examples include cellulose diacetate, cellulose acetate butyrate derivatives, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, and plastics such as polycarbonate, polyimide, and polyamideimide. The nonmagnetic support may be in any form such as a film, tape, sheet, disk, card, or drum.

Materials for the ferromagnetic metal thin film include metals such as Fe, Co, and Ni, Co-Ni alloy, Fe-Co alloy, Fe
-Ni alloy, Fe-Co-Ni alloy, Fe-Co
-B alloy, Co-Ni -Fe-B alloy, or these with Cr.

Examples include those containing metals such as 1st class.

Examples of methods for depositing the ferromagnetic metal thin film material include vacuum evaporation, ion blasting, and sputtering. The above vacuum evaporation method uses 164 to 10 Torr.
The ferromagnetic metal material is evaporated by resistance heating, high-frequency heating, electron beam heating, etc. in a vacuum of 300 nm, and the evaporated metal (ferromagnetic metal material) is deposited on a non-magnetic support, which is an oblique evaporation method. and vertical evaporation methods. The above-mentioned oblique deposition method is a method in which the above-mentioned ferromagnetic metal material is obliquely vapor-deposited on a non-magnetic support in order to obtain a high coercive force, and the above-mentioned vapor deposition is performed in an oxygen atmosphere in order to obtain a higher coercive force. Also includes things. In the vertical vapor deposition method, Bi, Sb, Pb, and Sn are deposited on a nonmagnetic support in advance in order to improve vapor deposition efficiency and productivity and to obtain high coercive force.

Ga, In, Cd, Ge, Si, Tj? A base metal layer is formed in advance, and the ferromagnetic metal material is vertically deposited on the base metal layer. The ion blating method mentioned above is also a type of vacuum evaporation method, and 10
−' ~10” Torr in an inert gas atmosphere
A glow discharge or RF glow discharge is generated, and the ferromagnetic metal is evaporated during the discharge.

The above sputtering method involves generating a glow discharge in an atmosphere containing argon gas as a main component at 10" to 10" Torr, and using the generated argon ions to knock out atoms on the target surface. Examples include pole and three-pole sputtering methods, high-frequency sputtering methods, and magnetron sputtering methods that utilize magnetron discharge.

[For production]

As mentioned above, by attaching a heterocyclic compound containing sulfur atoms to the surface, inside, or interface with the base of the ferromagnetic metal thin film that is the magnetic layer, the occurrence of rust in the ferromagnetic metal thin film is prevented. be done.

〔Example〕

Although specific examples of the present invention will be described below, it goes without saying that the present invention is not limited to these examples.

Example 1 Cobalt CO was applied onto a 12 μm thick polyethylene terephthalate film using a vacuum evaporator at an incident angle of 50°.
Oblique deposition was performed at an angle of ~90° to form a ferromagnetic metal thin film with a thickness of about 130 OA.

Next, a solution (0.1wt'4 solution) of sulfolane diluted in a mixed solvent of acetone and water (acetone:water=l:l) was applied onto the ferromagnetic metal thin film (coating amount: 20"!I).
F/m)L, a sample tape was created.

Example 2 A sample tape was prepared in the same manner as in Example 1, except that 3-hydroxysulfolane was used instead of sulfolane.

Example 3 A sample tape was prepared in the same manner as in Example 1, except that 3-methylsulfolane was used instead of sulfolane.

Example 4 A sample tape was prepared in the same manner as in Example 1, except that sulfolene was used instead of sulfolane.

Example 5 A sample tape was prepared in the same manner as in Example 1 except that 3-hydroxysulfolene was used instead of sulfolane.

Example 6 A sample tape was prepared in the same manner as in Example 1 except that 3-methylsulfolene was used instead of sulfolane.

Example 7 A sample tape was prepared in the same manner as in Example 1, except that rhodanine was used instead of sulfolane.

Example 8 A sample tape was prepared in the same manner as in Example 1 except that 3-aminorhodanine was used instead of sulfolane.

Example 9 A sample tape was prepared in the same manner as in Example 1, except that thianiso-4-carboxylic acid was used instead of sulfolane.

Example 1 A sample tape was prepared in the same manner as in Example 1 except that 4H-1,4-thiazine was used instead of sulfolane.

Example 11 A sample tape was prepared in the same manner as in Example 1, except that biotin was used instead of sulfolane.

Example 1 A sample tape was prepared in the same manner as in Example 1 except that 3,6-thioxasothuamine was used in place of 2° sulfolane.

Example 1 A sample tape was prepared in the same manner as in Example 1 except that 3,6-thioxanthinediamine-10,10 dioxide was used instead of 3° sulfolane.

Comparative Example Cobalt CO was applied onto a 12 μm thick polyethylene terephthalate film using a vacuum evaporator at an incident angle of 50°.
Oblique evaporation was performed at an angle of ~90° to form a ferromagnetic metal thin film with a thickness of about 130 OA, and a sample tape was prepared.

For each sample tape obtained in the above examples and comparative examples, initial coercive force (Hcl) and saturation magnetization (l
51) and the coercive force (HC2) and saturation magnetization (IS'2) after being left at 45° C. and 80 SRH for one week.

Rate of change in Hc - (Hcl - HC2) / Hc l■s
Rate of change = (ISI-IS2)/ISI The results are shown in the following table.

Further, no rust was observed on the surface of the sample tape of the example.

From the above table, it can be seen that in the magnetic recording medium according to the present invention, rust does not occur on the surface of the magnetic layer, and there is little change in the magnetic properties.

〔Effect of the invention〕

As is clear from the above description, in the present invention,
Since a rust preventive agent mainly composed of a heterocyclic compound containing sulfur atoms is attached to the ferromagnetic metal film, rust does not form on the surface of the ferromagnetic metal thin film, which is the magnetic layer, even under high temperature or high humidity conditions. This also reduces changes in magnetic properties such as coercive force and saturation magnetization.

Claims (1)

[Claims] 1. A magnetic recording medium comprising: a ferromagnetic metal thin film formed on a non-magnetic support; and a rust preventive agent containing a sulfur atom-containing heterocyclic compound as a main component attached to the ferromagnetic metal thin film.