JPS6182323A - 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. oxygen atoms 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 heterocyclic compd. contg. oxygen atoms is stuck on the thin ferromagnetic metallic film, by which the intended recording medium is obtd. The embodiment of the heterocyclic compd. is exemplified by tocopherol, morin, quencetin, ascorbic acid, resorufine, kojic 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, γ is recorded on a non-magnetic support.
-FezOa, Co-containing r-Fe 20B
, Fe 804, FegO+ containing Co, γ-
Powder magnetic materials such as bertolide compounds of FezOa and Fe3O4, bertolide compounds containing CO, oxide magnetic powders such as Cr0z, or alloy magnetic powders whose main components are Fe, Co, Ni, etc., are mixed with vinyl chloride-acetic acid. Coating-type magnetic recording media are widely used, which are obtained by coating and drying a magnetic paint dispersed in an organic binder such as a vinyl copolymer, polyester resin, or polyurethane resin.

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 has a coercive force I-I c and a residual magnetic flux density Br.
Not only is it large, but the thickness of the magnetic layer can be made extremely thin, so the thickness loss during recording demagnetization and reproduction is extremely small, and it is necessary to mix an organic binder, which is a non-magnetic material, into the magnetic layer. It has a number of advantages in terms of magnetic properties, such as the ability to increase the packing density of magnetic materials because there is no carbon.

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 preventives (JP-A-57-152517), diallyl ketone is used (JP-A-57-15251-8), and alkylphenols are used (JP-A-57-152519). issue)
, using naphthols (Japanese Patent Application Laid-Open No. 57-1525
'20) etc. are disclosed in the above publication.

[Problem that the invention seeks to solve]

The 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 with little change in magnetic properties. The purpose is to solve the above-mentioned problems by using a rust preventive 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 whose main component is a heterocyclic compound containing an oxygen atom is attached to the ferromagnetic metal thin film. It is characterized by this.

In the present invention, examples of the heterocyclic compound containing an oxygen atom used as a rust preventive include tocopherol, morin, quercetin, ascorbic acid, 1,8-nuclic anhydride,
Resorufin, kojic acid, dehydroacetic acid, oxazole, 3-amine phthalimide, 4-aminophthalimide,
Examples include uridine, thymidine, guanosine, isatoic anhydride, 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 cm per m2 of magnetic recording medium.

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

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 ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, alcohols such as methanol, ethanol, propatool, and butanol, methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and glycol monoethyl acetate. Esters such as ether, ethers such as ethylene glycol dimethyl ether, ethylene glycol monoethyl 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,
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.

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.

Ni, Co, Fe, AA? , Mg, Sr, Cu and other tono salts, -yuryl, palmityl, myristyl, stearyl,
Salts of sulfonic acids such as behenyl, oleyl, linole, and rinne 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,
Salts with Mg, Zn, Al, Fe, Co, Ni, etc., perfluoroalkyl phosphate esters, perfluoroalkylbequins, perfluoroalkyltrimethylammonium salts,
Perfluoroethylene oxide, perfluoroalkyl aliphatic ester, etc. can be used.

Materials for the non-magnetic support include polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, cellulose triacetate,
Cellulose derivatives such as cellulose diacetate and cellulose acetate + -phthylate, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, polycarbonate,
Examples include plastics such as 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 Fe, Co,
Metals such as Ni or Co-Ni alloy, Fe-Co alloy, Fe-Ni alloy, Fe-Co-Ni alloy, Fe-Co
-B alloy, Co-Ni -F"e-B alloy, or these with Cr.

Examples include those containing metals such as A1.

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 non-magnetic 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, T#, etc. is formed in advance, and the ferromagnetic metal material is vertically deposited on the base metal layer.

The above-mentioned ion blasting method is also a type of vacuum evaporation method, and D
C glow discharge and RF glow discharge are caused, and the ferromagnetic metal is evaporated during the discharge. The above sputtering method involves causing 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 surface of Kugett. 3
1=There are sputtering methods, high frequency sputtering methods, magnetron sputtering methods using magnetron discharge, etc.

[For production]

As mentioned above, by attaching a heterocyclic compound containing oxygen 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 is needless to say that the present invention is not limited to these examples.

Example 1 Kobal L-C was deposited on a 12 μm thick polyethylene terephthalate film using a vacuum deposition apparatus.

was obliquely deposited at an incident angle of 50° to 90°, and the film thickness was approximately 130°.
A ferromagnetic metal thin film A was formed.

Next, a solution (0,xwt% solution) of morin 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).
L. A sample tape was created.

Example 2 A sample tape was prepared in the same manner as in Example 1 except that tocopherol was used instead of morin.

Example 3 Example 1 except that quercetin was used instead of morin.
A sample tape was created in the same manner.

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

Example 5 A sample tape was prepared in the same manner as in Example 1 except that 1,8-naphthalic anhydride was used instead of morin.

Example 6 A sample tape was prepared in the same manner as in Example 1 except that resorufin was used instead of morin.

Example 7 A sample tape was prepared in the same manner as in Example 1 except that kojic acid was used instead of morin.

Example 8 A sample tape was prepared in the same manner as in Example 1, except that dehydroacetic acid was used instead of morin.

Example 9 A sample tape was prepared in the same manner as in Example 1 except that oxazole was used instead of morin.

Example 10 A sample tape was prepared in the same manner as in Example 1 except that 3-aminophthalimide was used instead of morin.

Example 11 A sample tape was prepared in the same manner as in Example 1 except that 4-aminophthalimide was used instead of morin.

Example 12 A sample tape was prepared in the same manner as in Example 1 except that uridine was used instead of morin.

Example 13 A sample tape was prepared in the same manner as in Example 1 except that thymidine was used instead of morin.

Example 14 Example 1 except that guanosine was used instead of morin.
A sample tape was created in the same manner.

Example 15 A sample tape was prepared in the same manner as in Example 1 except that isatoic anhydride was used instead of morin.

Comparative Example A sample tape was prepared by forming a ferromagnetic metal thin film of cobalt C00A on a polyethylene terephthalate film having a thickness of 12 μm using a vacuum evaporation device.

Regarding the valley sample tapes obtained in the above examples and comparative examples, the initial coercive force (HCI) and saturation magnetization (I
st) and the coercive force (Hc2) and saturation magnetization (IS2) after being left at 545° C. and 80% RH for one week.

Rate of change in Hc-(f(cz-Hc2)/rate of change in HCtIs-(Isl-IS2)/ISI The results are shown in the following table.

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

From the above table, it can be seen that the magnetic recording medium according to the present invention has almost no rust on the surface of the boron layer and shows little change in magnetic properties over time.

〔Effect of the invention〕

As is clear from the above description, in the present invention,
A rust preventive agent whose main component is a heterocyclic compound containing oxygen atoms is attached to the ferromagnetic metal thin film, which prevents rust from forming on the surface of the ferromagnetic metal thin film, which is the magnetic layer, even under high temperature or high humidity conditions. Therefore, 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 whose main component is a heterocyclic compound containing oxygen atoms adhered to the ferromagnetic metal thin film.