JPS6182324A - 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 compd. having a mercapto group to the thin ferromagnetic film of 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 compd. contg. mercapto group in stuck on the thin ferromagnetic metallic film, by which the intended magnetic recording medium is obtd. The embodiment of the compd. having a mercapto group is exemplified by 2-benzoxazole, thiol, thiophenol, thiosalicylic 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, 1-
7-Fezoa containing Pe2os, Co
, FeaO+, FeaO+ containing Co,
7-Bertride compound of Fe20a and Fe3O4, C
ferrite compound containing o, oxide magnetic powder such as CrO2, or Fe.

By applying and drying a magnetic paint in which a powder magnetic material such as alloy magnetic powder containing Co, Ni, etc. as the main components 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 have been deposited directly on non-magnetic supports using techniques such as vacuum evaporation, sputtering, ion blating, and plating. The ferromagnetic metal thin film magnetic recording media created by this method are attracting attention. This ferromagnetic metal thin film magnetic recording medium not only has a large coercive force Hc and a large residual magnetic flux density Br, but also allows the thickness of the magnetic layer to be made extremely thin, resulting in significant thickness loss during recording demagnetization and reproduction. It has many advantages in terms of magnetic properties, such as being small and being able to increase the packing density of the magnetic material because there is no need to mix an organic binder, which is a non-magnetic material, into the magnetic layer.

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 under high temperature or high humidity, resulting in the saturation magnetization. There was a problem in that the magnetic properties such as those caused by oral deterioration.

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.

[Problem that the invention seeks to solve]

An object of the present invention is to provide 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 the magnetic properties exhibit little change over time.
Furthermore, it is an attempt to solve the above-mentioned problems by using a new rust preventive agent.

[Failure to solve the problem]

That is, the magnetic recording medium according to the present invention includes a ferromagnetic metal thin film formed on a nonmagnetic support, and a rust preventive agent containing a compound having a mercapto group as a main component attached to the ferromagnetic metal thin film. Characteristics of rattan 5 - things.

In the present invention, compounds having a mercapto group that are used as rust preventives include 16≠su--2-benzooxy->nopurthiol, thiophenol, thiosalicylic acid, propanethiol, thiouracil, 2.3- Quinoxaline dithiol, dithizone, thioxin, 2-penzimidadurthiol, 6-thioguanine.

Examples include 5-nitro-2-hensimitasolthiol and 5-amino-1,3,4-thiazole-2-diol.

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 square meters per 1 i of 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

Also, it does not cause any damage even if a normal lubricant is used in combination with a rust preventive agent. Examples of the above-mentioned solvents include acemetone, methyl ethyl ketone, ethyl isobutyl ketone,
Ketones such as cyclohexanone, alcohols such as methanol, ethanol, propatool, butanol, esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, acetic acid glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl Ethers such as ether, tetrahydrofuran, and dioxane; aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as hexane and heptane; methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, and Chlorinated hydrocarbons such as chlorobenzene, trichlorofluoromethane, dichlorodifluoromethane, chlorotrifluoromethane, chlorodifluoromethane, 1,1.2-trichloro-1,
Examples include fluorohydrocarbons such as 2゜2-trifluoroethylene and 3-dichlorotetrafluoroethylene, water, and mixed solvents thereof.

Furthermore, as lubricants, fatty acids, fatty acid esters, fatty acid amides, metal soaps, fatty alcohols, paraffin,
Silicone, fluorine-based 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.

Salts with Ni, Co, Fe, AA, Mg, Sr, Cu, etc., salts of sulfonic acids such as lauryl, palmityl, myristyl, stearyl, behenyl, oleyl, linole, rinne, and the above metals, and the like 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,
Mg, Zn, A4. Salts with Fe, Co, Ni, etc., perfluoroalkyl phosphate esters, perfluoroalkylhetaines, perfluoroalkyltrimethylammonium salts,
Perfluoroethylene oxide, perfluoroalkyl aliphatic ester, etc. can be used.

Materials for the nonmagnetic support include polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose I-lyacetate, cellulose diacetate-1, and cellulose acetate-butycetate-1, and polychloride. vinyl,
Examples include vinyl resins such as polyvinylitine 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, pe-Co-Ni alloy, re-Co-B alloy, Co-Ni -Fe -B alloy or these with Cr
.

Examples include those containing metals such as AA.

Examples of methods for depositing the ferromagnetic metal thin film material include vacuum evaporation, ion blasting, and sputtering. The above vacuum evaporation method uses 10 to 10 Torr.
The method involves depositing the evaporated metal (ferromagnetic metal material) on a non-magnetic support by evaporating the ferromagnetic metal material by resistance heating, high-frequency heating, electron beam heating, etc. in a vacuum of It is broadly divided into 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 deposition method, Bi and Sb are deposited on a nonmagnetic support in advance in order to improve deposition efficiency and productivity and to obtain high coercive force.

A base metal layer of Pb, Sn, Ga, In, Cd, Ge, Si, T1, etc. is formed in advance, and the ferromagnetic metal material is vertically deposited on the base metal layer.

The above ion blating method is also a type of vacuum evaporation method, and D
C glow discharge, R, F glow discharge is caused, and the above-mentioned ferromagnetic metal is evaporated during the discharge. The above sputtering method involves causing glow discharge in an atmosphere mainly composed of argon gas at 10-3 to 10" Torr, and using the generated argon ions to knock out atoms on the target surface. There are two-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 compound having a mercapto group 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 can be prevented. .

〔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 deposited on 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 (Q, 1 wt % solution) of thiophenol diluted in a mixed solvent of acetone and water (acetone:water = 1:1) was applied onto the ferromagnetic metal thin film (coating amount: 20 m).
9/rrl) to create a sample tape.

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

Example 3 A sample tape was prepared in the same manner as in Example 1, except that thiosalicylic acid was used instead of thiophenol.

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

Example 5 A sample tape was prepared in the same manner as in Example 1 except that thiouracil was used instead of thiophenol.

Example 6 A sample tape was prepared in the same manner as in Example 1, except that 2,3-quinoxaline dithiol was used instead of thiophenol.

A sample tape was prepared in the same manner as in Example 1 except for this.

Example 8 A sample tape was prepared in the same manner as in Example 1 except that 2-benzimidazole thiol was used instead of thiophenol.

Example 9 A sample tape was prepared in the same manner as in Example 1, except that 6-thioguanine was used instead of thiophenol.

Example 10 A sample tape was prepared in the same manner as in Example 1 except that 2-thiazoline-2thiol was used instead of thiophenol.

Example 11 A sample tape was prepared in the same manner as in Example 1, except that 5-nitro-2-benzimidazole thiol was used instead of thiophenol.

Example 1 A sample tape was prepared in the same manner as in Example 1, except that 5-amino-113°4-thiazole-2-thiol was used instead of 2°thiophenol.

Comparative Example Conolt CO was applied onto a 12 μm thick polyethylene terephthalate film at an incident angle of 50 using a vacuum evaporator.
A sample tape was prepared by performing oblique deposition at an angle of ~90° to form a ferromagnetic metal thin film with a thickness of about 1.300 A.

For each sample tape obtained in the above examples and comparative examples, initial coercive force (HCI) and saturation magnetization (I
The rate of change was determined from the coercive force (HO2) and saturation magnetization (IS2) after leaving the sample at 45° C. and 580% R'H for one week.

Rate of change in Hc = (HCI HO2)/HCI 'I
Rate of change in s=(■st l52)/ISI 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, almost no rust occurs 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 compound having a mercapto group is attached to the ferromagnetic metal thin film, rust is prevented from forming on the surface of the ferromagnetic metal thin film, which is the magnetic layer, even under high temperature or high humidity conditions. Oral changes in magnetic properties such as coercive force and saturation magnetization amount are also small.

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 compound having a mercapto group as a main component adhered to the ferromagnetic metal thin film.