JPH0816979B2 - Magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a so-called ferromagnetic metal thin film formed as a magnetic layer on a non-magnetic support by a technique such as a vacuum thin film forming technique such as vacuum evaporation or sputtering. The present invention relates to a ferromagnetic metal thin film type magnetic recording medium.

[Outline of Invention]

The present invention is a magnetic recording medium comprising a ferromagnetic metal thin film formed as a magnetic layer on a non-magnetic support, wherein a ferromagnetic metal thin film which is a magnetic layer is coated with a dicarboxylic acid fluorinated alkyl ester as a lubricant, It aims to provide a magnetic recording medium that exhibits excellent running properties, wear resistance, and durability under all usage conditions.

[Conventional technology]

Conventionally, as a magnetic recording medium, γ has been formed on a non-magnetic support.
-Fe ₂ O ₃ , Co containing γ-Fe ₂ O ₃ , Fe ₃ O ₄ , Co containing F
e ₃ O ₄ , γ-Fe ₂ O ₃ and Fe ₃ O ₄ beltride compounds, B containing compounds containing Co, oxide ferromagnetic powder such as CrO ₂ or Fe, Co, Ni Coating type magnetic material prepared by coating and drying a magnetic paint in which a powder magnetic material such as alloy magnetic powder is dispersed in an organic binder such as vinyl chloride-vinyl acetate copolymer, polyester resin or polyurethane resin. Recording media are widely used.

On the other hand, with the increasing demand for high-density magnetic recording, a ferromagnetic metal material such as Co-Ni alloy is coated with polyester by plating or vacuum thin film forming technology (vacuum deposition method, sputtering method, ion plating method, etc.). A so-called ferromagnetic metal thin film type magnetic recording medium, which is directly deposited on a non-magnetic support such as a film or a polyimide film, has been proposed and has attracted attention. This ferromagnetic metal thin film type magnetic recording medium is not only excellent in coercive force and squareness ratio and excellent in electromagnetic conversion characteristics at short wavelengths, but it is also possible to make the thickness of the magnetic layer extremely thin so that recording demagnetization is possible. Also, there are various advantages such as a remarkably small thickness loss at the time of reproduction and an increase in the packing density of the magnetic material because it is not necessary to mix an organic binder which is a specific magnetic material in the magnetic layer.

However, in the above-mentioned ferromagnetic metal thin film type magnetic recording medium, since the smoothness of the magnetic layer surface is extremely good, the substantial contact area becomes large, and the adhesion phenomenon (so-called sticking) easily occurs or friction There are many shortcomings in durability and runnability, such as a large coefficient, and their improvement is a major issue. In general, a magnetic recording medium is subjected to high-speed relative motion with a magnetic head in the process of recording / reproducing a magnetic signal, and at that time, the running must be performed smoothly and in a stable state. Further, it is preferable that wear and damage due to contact with the magnetic head be as small as possible.

Therefore, for example, it has been attempted to improve the durability and the running property by applying a lubricant to the surface of the magnetic layer of the magnetic recording medium, that is, the surface of the ferromagnetic metal thin film to form a protective film.

[Problems to be solved by the invention]

By the way, when a protective film is formed by applying a lubricant as described above, the protective film exhibits good adhesion to a ferromagnetic metal thin film as a magnetic layer and exhibits a high lubricating effect. Is required. Further, these adhesion and lubricating effect must be excellent under high temperature and high humidity conditions such as in tropical regions and subtropical regions, and under low temperature conditions such as cold regions.

However, the operating temperature range of the lubricants that have been widely used in the past is limited, and in particular, many of them solidify or freeze at a low temperature such as 0 to −5 ° C., and sufficiently exert their lubricating effect. I couldn't.

Therefore, the present invention provides a magnetic recording medium excellent in running property and durability, which provides a lubricant whose adhesion and lubricity are maintained under any use condition and whose lubricating effect lasts for a long period of time. With the goal.

[Means for solving problems]

The inventors of the present invention have found that the dicarboxylic acid fluorinated alkyl ester exerts a good lubricating effect over a wide temperature range as a result of earnestly researching what does not achieve the above object, and has completed the present invention. The invention is characterized in that a ferromagnetic metal thin film is formed on a non-magnetic support, and a lubricant containing a dicarboxylic acid fluorinated alkyl ester is coated on the ferromagnetic metal thin film.

The dicarboxylic acid fluorinated alkyl ester used as a lubricant in the present invention has the following formula (However, in the formula, R represents a hydrocarbon group having 1 to 25 carbon atoms, and n
≧ 3 and 0 ≦ m ≦ 5. ) Fluorinated alkyl monoesters of dicarboxylic acid represented by [Wherein R represents a hydrocarbon group, and n ≧ 3, 0 ≦ m ≦
It is 5. ] A dicarboxylic acid fluorinated alkyl diester represented by

Hydrocarbon group R in the carboxylic acid moiety of the dicarboxylic acid fluorinated alkyl ester represented by the above formula (I) or (II)
May be linear or branched, and may further contain a double bond, an aromatic ring or the like, but the carbon number thereof is preferably 6 or more.

Further, n is preferably an integer of 3 or more, and preferably 5 or more, the lubricity is remarkable.

The dicarboxylic acid fluorinated alkyl ester represented by the above formula (I) can be easily obtained by reacting a carboxylic acid anhydride and perfluoroalcohol in the presence of an acidic catalyst, and is represented by the above formula (II). The fluorinated dicarboxylic acid alkyl ester can be easily obtained by reacting dicarboxylic acid chloride with perfluoroalcohol in the presence of a base.

Furthermore, the general formula (However, in the formula, R and R ′ represent a hydrocarbon group, and n ≧ 3,
0 ≦ m ≦ 5. It is also possible to use one having a perfluoroalkyl group only in one ester part of the dicarboxylic acid diester as shown in (4) and the other ester part consisting of a normal hydrocarbon group.

R ′ of the dicarboxylic acid fluorinated alkyl ester represented by the above formula (III) may be a linear or branched alkyl group having 3 or more carbon atoms, and a double bond,
It may contain an aromatic ring or the like.

The dicarboxylic acid fluorinated alkyl ester represented by the above formula (III) can be easily prepared by acid chloride conversion of a monoester obtained by reacting a carboxylic acid anhydride with an alcohol, and then reacting with a perfluoroalcohol using a base as a catalyst. Can be obtained.

Although the above-mentioned dicarboxylic acid fluorinated alkyl ester may be used alone as a lubricant, it may be used as a mixture with a conventionally known lubricant to further expand the operating temperature range.

Examples of the lubricant used include a fatty acid or a metal salt thereof, a fatty acid amide, a fatty acid ester, an aliphatic alcohol or an alkoxide thereof, an aliphatic amine, a polyhydric alcohol, a sorbitan ester, a mannittane ester, a sulfurized fatty acid, an aliphatic mercaptan, Modified silicone oil, perfluoroalkylethylene oxide, perfluoropolyethers, higher alkylsulfonic acid or its metal salt, perfluoroalkylsulfonic acid or its ammonium salt or its metal salt, perfluoroalkylcarboxylic acid or its metal salt, perfluoro Examples thereof include an alkyl carboxylate.

In particular, the general formula C _n F _{2n + 1} COOR (wherein n represents an integer of 6 to 10 and R represents a hydrocarbon group having 1 to 25 carbon atoms).
Since the perfluoroalkylcarboxylic acid ester represented by the formula (3) also has good low-temperature characteristics, it is suitable for use in combination with the above dicarboxylic acid fluorinated alkyl ester.

Further, an extreme pressure agent may be used in combination at a weight ratio of about 30:70 to 70:30 in order to cope with more severe use conditions and to maintain the lubricating effect.

The above extreme pressure agent reacts with the metal surface by frictional heat generated when a metal contact is partially generated in the boundary lubrication region, and forms a reaction product film to prevent friction and wear. Therefore, phosphorus-based extreme pressure agents, sulfur-based extreme pressure agents, halogen-based extreme pressure agents, organometallic extreme pressure agents, composite type extreme pressure agents and the like are known.

More specifically, as the phosphorus-based extreme pressure agent, tributyl phosphate, trioctyl phosphate, tri-2-ethylhexyl phosphate, trilauryl phosphate, trioleyl phosphate, dibutyl phosphate, dioctyl phosphate, di-2-ethylhexyl phosphate can be used. , Dilauryl phosphate, dioleyl phosphate, etc., tributyl phosphite, trioctyl phosphite, tri-2-ethylhexyl phosphite, trilauryl phosphite,
Phosphites such as trioleyl phosphite, dibutyl phosphite, dioctyl phosphite, di-2-ethylhexyl phosphite, dilauryl phosphite, and dioleyl phosphite; dibutyl phosphate butylamine salt; dibutyl phosphate octylamine salt;
Dibutyl phosphate stearylamine salt, dioctyl phosphate butylamine salt, dioctyl phosphate octylamine salt, dioctyl phosphate laurylamine salt, dioctyl phosphate stearylamine salt,
Di-2-ethylhexyl phosphate butylamine salt,
Di-2-ethylhexyl phosphate octylamine salt, di-2-ethylhexyl phosphate laurylamine salt, di-2-ethylhexyl phosphate stearylamine salt, dilauryl phosphate butylamine salt, dilauryl phosphate octylamine salt, dilauryl phosphate laurylamine salt, Phosphate amine salts such as dilauryl phosphate stearylamine salt, dioleyl phosphate butylamine salt, dioleyl phosphate octylamine salt, dioleyl phosphate laurylamine salt, and dioleyl phosphate stearylamine salt.

Examples of the sulfur type extreme pressure agent include mineral oil having an unsaturated bond such as sulfurized macaroleum oil, sulfurized dipentene, sulfurized oils and fats produced by adding sulfur to oils and fats and fatty acids, etc., dibenzyl disulfide, and disulfide disulfide. Diphenyl, disulfide
t-butyl, di-sec-butyl disulfide, di-n-disulfide
Disulfides such as butyl, di-t-octyl disulfide, diethyl disulfide, benzyl sulfide, diphenyl sulfide, divinyl sulfide, dimethyl sulfide, diethyl sulfide, di-t sulfide
Monosulfides such as -butyl, di-sec-butyl sulfide and di-n-butyl sulfide; dimethyl trisulfide;
polysulfides such as t-butyl, poly-di-t-nonyl sulfide, and olefin polysulfide; Or (Wherein, R represents a hydrocarbon group.), Thiocarbonates, elemental sulfur and the like.

Examples of the halogen-based extreme pressure agent include bromine compounds such as allyl bromide, octadecyl bromide, cyclohexyl bromide, stearyl bromide, and benzyl bromide, benzyl iodide, allyl iodide, butyl iodide, octadecyl iodide, and iodine. Iodine compounds such as cyclohexyl chloride, hexachloroethane, monochloroethane, chlorinated paraffin, chlorinated diphenyl, chlorinated fats and oils, methyltrichlorostearate, pentachloropentadienoic acid, esters of hexachloronaphthenic acid compounds, imides of hexachloronaphthenic acid compounds And chlorine compounds such as derivatives.

Examples of the organometallic extreme pressure agent include zinc diisobutyldithiophosphate, zinc isobutylpentyldithiophosphate, zinc isopropyl-1-methylbutyldithiophosphate, zinc isobutylnonylphenyldithiophosphate, zinc isobutylheptylphenyldithiophosphate, and zinc diheptylphenyldithiophosphate. Thiophosphates such as zinc, zinc dinonylphenyldithiophosphate, molybdenum dithiophosphate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate,
Zinc ethylphenyldithiocarbamate, zinc dibenzyldithiocarbamate, copper dimethyldithiocarbamate, iron dimethyldithiocarbamate, selenium diethyldithiocarbamate, silver diethyldithiocarbamate, and other thiocarbamate salts, molybdenum, antimony, and other metal alkyldithiocarbamate salts, etc. Is mentioned.

Examples of the complex type extreme pressure agent include dialkylthiophosphate amines such as di-2-ethylhexylthiophosphate amine,
Other than halogenated alkyl phosphates such as propyl chloride chloride, propyl bromide phosphate, propyl iodide phosphate, butyl chloride chloride, butyl bromide phosphate, butyl iodide phosphate, etc. formula Wherein R represents a hydrogen atom or an alkyl group, an alkenyl group, or an aryl group. (However, in the formula, R represents a hydrogen atom or an alkyl group, an alkenyl group, or an aryl group.) The thiophosphites and the like are highly effective.

The above extreme pressure agents may be used alone, but two or more kinds may be used in combination.

As a method of adhering a lubricant layer containing these dicarboxylic acid fluorinated alkyl esters on the ferromagnetic metal thin film, a solution obtained by dissolving the lubricant in a solvent is applied or sprayed on the surface of the ferromagnetic metal thin film. Alternatively, or conversely, the ferromagnetic metal thin film may be dipped in this solution and dried.

Here, the coating amount is preferably from ^{0.5mg / m 2 ~100mg / m 2} , and more preferably ^{1mg / m 2 ~20mg / m 2} . If this coating amount is too small, the effects of lowering the friction coefficient and improving wear resistance and durability will not be manifested, while if it is too large, the sticking phenomenon will occur between the sliding member and the ferromagnetic metal thin film. On the contrary, the running performance becomes worse.

Alternatively, in addition to the above-mentioned lubricant and extreme pressure agent, a rust preventive agent may be used in combination if necessary.

In general, a ferromagnetic metal thin film is formed of a metal material, and is therefore easily rusted, and the use of the above-mentioned rust preventive agent greatly improves the corrosion resistance. Therefore, the durability of the magnetic recording medium can be improved in combination with the lubricating action of the lubricant containing the fluorinated alkyl dicarboxylic acid.

The rust preventive agent that can be used may be the following as long as it is usually used as a rust preventive agent for magnetic recording media of this type, for example, phenols, naphthols,
Examples include quinones, diaryl ketones, heterocyclic compounds containing a nitrogen atom, heterocyclic compounds containing an oxygen atom, heterocyclic compounds containing a sulfur atom, compounds having a mercapto group, thiocarboxylic acids or salts thereof, and thiazole compounds. A specific example is as follows.

First, as the above-mentioned phenols, dihydric phenol,
Alkyl phenols or nitrosophenols are mentioned.

Examples of the dihydric phenol include pure phenols such as hydroquinone, resorcin, and catechol, and alkylamino, nitro, and halogeno-substituted products thereof, for example,
-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-resorcinol, 2,5-dichlorohydroquinone and the like can be mentioned. The alkylphenol refers to an alkyl-substituted monohydric phenol, for example, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, 2,3-dimethylphenol , 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4,6-trimethylphenol, 2,4,5-trimethylphenol, 5-isopropyl -2-methylphenol, p-
tert-butylphenol, 2,6-di-tert-butyl-p-
Cresol, 4,4'-methylenebis2,6-di-tert-butylphenol, 2,6-dimethyl-4-tert-butylphenol, 2,4,6-tri-tert-butylphenol and the like can be mentioned.

Examples of the nitrophenol include 4-nitroso-2-methoxy-1-phenol and 4-nitroso-2-
Ethoxy-1-phenol, 6-nitroso-o-cresol, 4-nitroso-m-cresol, o-nitrosophenol, 2-nitrosophenol, 2-nitrosoresorcin, 4-
Nitrosoresorcin, p-nitrosophenol, etc. are mentioned.

Next, as the naphthols, α-naphthol,
β-naphthol, 1,2-naphthalene diol, 1,3-naphthalene diol, 1,4-naphthalene diol, 1,5-naphthalene diol, 1,7-naphthalene diol, 1,8-naphthalene diol, 2,3- Pure naphthols such as naphthalene diol, 1,4,5-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-naphthol Naphthol and the like.

Examples of the quinones include quinones having no substituent such as p-benzoquinone, o-benzoquinone, 1,2-naphthoquinone, 1,4-naphthoquinone, 2,6-naphthoquinone, anthraquinone, 9,10-phenanthrenequinone, and diphenoquinone. Methylquinones such as methyl-p-benzoquinone, 2,3-dimethyl-p-benzoquinone, 2-methyl-1,4-naphthoquinone, 2-methylanthraquinone, and 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 -Hydroxyquinones such as trihydroxyanthraquinone, 1,2,4-trihydroxyanthraquinone, 1,2,5-trihydroxyanthraquinone, 1,2,6-trihydroxyanthraquinone, 1,2,7-trihydroxyanthraquinone, 2-aminoanthraquinone, 1,2-
Aminoquinones such as diaminoanthraquinone; nitroquinones such as 1-nitroanthraquinone and 1,5-dinitroanthraquinone; halogenoquinones such as 2,6-dichloro-p-benzoquinone, tetrachloro-p-benzoquinone and tetrabromo-p-benzoquinone; Alternatively, quinones having two or more substituents, for example, 2,5-dichloro-3,6-
Dihydroxy-p-benzoquinone, 1-methyl-2-hydroxy-1,4-naphthoquinone and the like.

Examples of the diaryl ketone include benzophenone and its derivatives, for example, benzophenone, 4-methylbenzophenone, 3-methylbenzophenone, 3,4-dimethylbenzophenone, 4,4'-dimethylbenzophenone,
3,4'-dimethylbenzophenone, alkyl-substituted compounds such as 4-ethylbenzophenone, 4-hydroxybenzophenone, 4,4'-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 2,4-dihydroxybenzophenone, 2, 2 ', 5,6'-tetrahydroxybenzophenone,
Hydroxybenzophenones such as 2,3 ', 4,4', 6-pentahydroxybenzophenone, aminobenzophenones such as 4-aminobenzophenone and 4,4'-diaminobenzophenone, or benzophenones having two or more substituents For example, 4-methoxy-2-hydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone and the like can be mentioned.

Examples of the heterocyclic compound containing a nitrogen atom include acridine, 2,2 ', 2 "-terpyridyl neocuproine and 2,2'-
In addition to dipyridylbenzotriazole, 5-methylbenzotriazole, bathophenanthroline, 1,10-phenanthroline, aldehyde collidine, benzylpyridine, phenylpyridine, quinazoline, 2-heptadecylimidazole and the like, compounds having a phenolic hydroxyl group, for example 4- (2-pyridylazo) -resorcin 1- (2-pyridylazo) -2-naphthol, 4-quinolinol, 4-methyl-2-quinolinol, 8-quinolinol, quinolinediol, etc., compounds having a carboxyl group, such as kynurenic acid, Compounds having an amino group or an imino group such as acridine acid, attophan, kyrnazinic acid, cinchonic acid, isonicotinic acid, 2,5-pyridinedicarboxylic acid, quinic acid, for example, 2-aminobenzimidazole, 5-amino-
Compounds having a carbonyl group such as 1H-tetrazole, 5-amino-1H-1,2,4-triazole, adenine, guanine, luminol, 2-hydrazinoquinoline and thiamine, for example, riboflavin, theobromine, allantoin, alloxan, 2- Examples thereof include thiobarbituric acid, violuric acid, isatin, hydantoin, thymine, barbituric acid, orotic acid, uracil, succinimide, creatinine, and 2-pyrrolidone.

Examples of the above-mentioned heterocyclic compound containing an oxygen atom include tocopherol, morin, quercetin, ascorbic acid, 1,1,2
8-Naphthalic acid, resorufin, kojic acid, dehydroacetic acid, oxazole, 3-aminophthalimide, 4-aminophthalimide, uridine, thymidine, guanosine, isatoic anhydride and the like.

Examples of the heterocyclic compound containing a sulfur atom include sulfolane, 3-hydroxysulfolane, 3-methylsulfolane, sulfolene, 3-hydroxysulfolene, 3-methylsulfolene, rhodanine, 3-aminorhodanine, and thiazoline-4.
-Carboxylic acid, 4H-1,4-thiazine, biotin, 3,6-thioxanthenediamine, 3,6-thioxanthenediamine-1
0,10-dioxide and the like can be mentioned.

Examples of the compound having a mercapto group include 2-benzoxazolethiol, thiophenol, thiosalicylic acid, propanethiol, thiouracil, 2,3-quinoxalinedithiol, dithizone, thiooxin, 2-benzimidazolethiol, 6-thioguanine, and 5-nitro. -2-
Examples thereof include benzimidazole thiol, 5-amino-1,3,4-thiazole-2-thiol and the like.

Examples of the thiocarboxylic acid or its salt include sodium diethyldithiocarbamate, ethanethioic acid, rubeanic acid, thioacetamide, ethanedithioic acid and the like.

As the thiazole compound, bismuthiol I
I, diazosulfide, azosulfim, 1,3,4-thiadiazole, bismthiol, biazthiol, benzothiazole, 2-methylbenzothiazole, 2- (p-aminophenyl) -6-methylbenzothiazole, 2-mercaptobenzothiazole, benzo Thiazoline, 2-benzothiazoline, benzothiazolone and the like.

The rust preventive may be used by mixing with the lubricant, but for example, the rust preventive is first applied to the surface of the ferromagnetic metal thin film, and then the lubricant containing the dicarboxylic acid fluorinated alkyl ester. It is highly effective to apply the coating in two or more layers such as coating.

In the case of coating in two layers as described above, the coating amount of the above-mentioned rust preventive agent is 0.5 mg / m ² to 10 as in the case of the above lubricant.
Is preferably from 0 mg / m ^2, and more preferably ^{1mg / m 2 ~20mg / m 2} . If the coating amount is too small, the effect of improving the corrosion resistance is insufficient, and conversely, if it is too large, problems such as running properties occur.

The magnetic recording medium to which the present invention is applied has a ferromagnetic metal thin film provided as a magnetic layer on a non-magnetic support.
Here, as the material of the nonmagnetic support, polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose triacetate, cellulose diacetate and cellulose acetate butyrate, polyvinyl chloride,
Vinyl-based resins such as polyvinylidene chloride, plastics such as polycarbonate, polyimide, polyamide-imide,
Examples include light metals such as aluminum alloys and titanium alloys, and ceramics such as alumina glass. The form of the non-magnetic support may be any of a film, a sheet, a disk, a card, a drum and the like.

The non-magnetic support may be formed with one or more types of protrusions such as mountain-like protrusions, wrinkle-like protrusions, and granular protrusions on the surface to control the surface roughness.

The above-mentioned mountain-shaped projections have a particle size, for example, when a polymer film is formed.
It is formed by internally adding inorganic fine particles of about 500 to 3000 mm, and the height from the polymer film surface is 100 to 1000
Å, the density is approximately 1 × 10 ⁴ to 10 × 10 ⁴ pieces / mm ² . Calcium carbonate (CaCO ₃ ), silica, alumina and the like are suitable as the inorganic fine particles used for forming the mountain-shaped projections.

The wrinkle-like protrusions are undulations formed by applying and diluting a dilute solution of a resin using a specific mixed solvent, and the height thereof is 0.01 to 10 μm, preferably 0.03 to 0.
5 μm, and the shortest interval between projections is 0.1 to 20 μm. As the resin for forming the wrinkle-like protrusions, saturated polyester such as polyethylene terephthalate and polyethylene naphthalate, polyamide, polystyrene, polycarbonate, polyacrylate, polysulfone, polyether sulfone, polyvinyl chloride, polyvinylidene chloride, polyvinyl butyral. , Polyphenylene oxide, phenoxy resin, and various other resins, simple substances, mixtures, or copolymers, and those having a soluble solvent are suitable. Then, in a solution having a resin concentration of 1 to 1000 ppm in which these resins are dissolved in the good solvent, a poor solvent for the resin having a boiling point higher than that of the good solvent is added to the resin in an amount of 10 to 10 ppm.
Apply 0 times the amount of the solution added to the surface of the polymer film.
By drying, a thin layer having very fine wrinkle-like irregularities can be obtained.

The granular protrusions are formed by attaching organic ultrafine particles such as acrylic resin or inorganic fine particles such as silica or metal powder in a spherical or hemispherical shape. The height of the granular projections is 50 to 500Å, and the density is about 1 × 10 ⁶ to 50 × 10 ⁶ pieces / mm ² .

If at least one of these projections is formed, the surface property of the ferromagnetic metal thin film as the magnetic layer is controlled, but the effect is increased by combining two or more thereof, and particularly, wrinkles are formed on the base film provided with the mountain-like projections. When the projections and the projections are formed, the durability and the running property are extremely improved.

In this case, the overall height of the projections is 100-2000Å
The density is preferably 1 × 10 ⁵ to 1 × 10 ⁷ per 1 mm ^{2 on} average.

The ferromagnetic metal thin film that is the magnetic layer is formed as a continuous film by a vacuum thin film forming technique such as a vacuum deposition method, an ion plating method, and a sputtering method.

In the above-mentioned vacuum deposition method, a ferromagnetic metal material is evaporated under a vacuum of 10 ^-4 to 10 ^-8 Torr by resistance heating, high-frequency heating, electron beam heating, etc., and the evaporated metal (ferromagnetic metal material) is deposited on the disk substrate. In order to obtain a high coercive force, an oblique deposition method of obliquely depositing the ferromagnetic metal material on a substrate is generally employed. Alternatively, the above-mentioned vapor deposition in an oxygen atmosphere to obtain a higher coercive force is also included.

The ion plating method is also a kind of vacuum evaporation method, and causes a DC glow discharge and an RF glow discharge in an inert gas atmosphere of 10 ^-4 to 10 ^-3 Torr to evaporate the ferromagnetic metal material during the discharge. It is to let.

The sputtering method is to cause a glow discharge in an atmosphere containing 10 ^-3 to 10 ^-1 Torr of argon gas as a main component, and to strike out atoms on a target surface with generated argon gas ions. Depending on the type, there is a DC two-pole or three-pole sputtering method, a high-frequency sputtering method, a magnetron sputtering method using magnetron discharge, or the like. When this sputtering method is used, a base film of Cr, W, V or the like may be formed.

In any of the above methods, a base metal layer such as Bi, Sb, Pb, Sn, Ga, In, Cd, Ge, Si.Tl is formed on the substrate in advance, and the substrate surface is formed. By forming the film in the vertical direction, a magnetic layer having no magnetic anisotropy orientation and excellent in-plane isotropy can be formed, which is suitable for a magnetic disk, for example.

When forming a metal magnetic thin film by such a vacuum thin film forming technique, the ferromagnetic metal materials used include Fe, C
In addition to metals such as o and Ni, Co-Ni alloys, Co-Pt alloys, Co-Ni-Pt
Alloy, Fe-Co alloy, Fe-Ni alloy, Fe-Co-Ni alloy, Fe-Co-B
Alloy, Co-Ni-Fe-B alloy, Co-Cr alloy or Cr,
Examples include those containing a metal such as Al. In particular, Co
When a -Cr alloy is used, a perpendicular magnetic film is formed.

The thickness of the magnetic layer formed by such a method is 0.
It is about 04 to 1 μm.

Further, a so-called back coat layer may be formed on the surface of the non-magnetic support opposite to the surface on which the magnetic layer is provided. The back coat layer is formed by applying a back coat coating material in which a binder resin and a powder component are mixed and dispersed in an organic solvent to the surface of the non-magnetic support.

Here, as the binder resin used in the coating material for the back coat, for example, vinyl chloride-vinyl acetate copolymer,
Vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, thermoplastic polyurethane elastomer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, Polyamide resin, polyvinyl butyral, cellulose derivative, polyester resin, synthetic rubber resin such as polybutadiene, phenol resin, epoxy resin, polyurethane curable resin, melamine resin, alkyd resin, silicone resin, acrylic reaction resin, epoxy-polyamide resin, Nitrocellulose-melamine resin, mixture of high molecular weight polyester resin and isocyanate prepolymer, mixture of methacrylate copolymer and diisocyanate prepolymer, poly A mixture of ester polyol with a polyisocyanate, urea formaldehyde resin, mixture of low molecular weight glycol / high molecular weight diol / triphenylmethane triisocyanate, polyamine resin, and mixtures thereof.

Alternatively, a binder resin having a hydrophilic polar group may be used in order to improve the dispersibility of the powder component.

In particular, (In the formula, M represents a hydrogen atom or an alkali metal, and M '
Represents a hydrogen atom, an alkali metal or a hydrocarbon group. )
Polyurethane resin, polyester resin, vinyl chloride-vinyl acetate type copolymer, vinylidene chloride type copolymer, acrylic ester type copolymer, butadiene type copolymer, etc. having hydrophilic polar group selected from It is possible.

As a method for introducing the hydrophilic polar group, various methods are conceivable depending on the type of resin. For example, in order to introduce the hydrophilic polar group into a polyurethane resin or a polyester resin, the following method is used. Good.

(1) 2 which is a raw material of polyurethane or polyester
A method of previously introducing the hydrophilic polar group into a basic acid, a polyol or the like.

(2) A method of leaving an OH group at the terminal or side chain and modifying the OH group with a compound having a hydrophilic polar group.

In the case of the method of (2), (2) -1 a compound containing a hydrophilic polar group and a halogen (for example, chlorine) in the molecule and a polyfunctional polyol as a raw material are used at the end or side chain of the polymer chain. Polyurethane resin or polyester resin with residual OH groups is dissolved in a solvent such as dimethylformamide, dimethylsulfoxide, etc., in which both components are soluble, and amines such as pyridine, picoline, triethylamine, etc. and epoxy such as ethylene oxide, propylene oxide, etc. A method for introducing a hydrophilic polar group by a dehydrochlorination reaction between an OH group and chlorine in the presence of a dehydrochlorination agent such as a compound.

(2) -2 A compound containing a hydrophilic polar group and an OH group in the molecule,
A method of reacting a polyurethane resin or a polyester resin in which an OH group remains at the terminal or side chain of a polymer chain via a diisocyanate compound.

There is.

Further, in order to introduce a hydrophilic polar group into the copolymer binder resin, (3) a method using a compound having a hydrophilic polar group and a copolymerizable double bond as the copolymerization monomer.

(4) As a copolymerization monomer, a compound having active hydrogen and a double bond capable of copolymerization is used, and the active hydrogen is introduced into the side chain of the copolymer so that the hydrophilic polar group and the active hydrogen are combined. A method of modifying with a compound having a reactive group.

(5) As the copolymerization monomer, a compound having a group capable of reacting with active hydrogen and a copolymerizable double bond is used,
A method in which a group capable of reacting with the active hydrogen is introduced into the side chain of the copolymer and modified with a compound having a hydrophilic polar group and the active hydrogen.

Etc.

On the other hand, examples of the powder component include carbon-based fine powder for imparting conductivity (for example, furnace carbon, channel carbon, acetylene carbon, thermal carbon, lamp carbon, etc., among which furnace carbon and thermal carbon are preferable. Suitable),
Added the alpha-FeOOH for inorganic pigments (surface roughness control and _{durability, α-Fe 2 O 3,} Cr 2 O 3, TiO 2, Zn
O, SiO, SiO ₂ , SiO ₂・ 2H ₂ O, Al ₂ O ₃・ 2SiO ₂・ 2H ₂ O ・ 3MgO ・
4SiO ₂ · H ₂ O, MgCO ₃ · Mg (OH) ₂ · 3H ₂ O, Al ₂ O ₃ , CaCO ₃ , Mg
CO ₃ , Sb ₂ O _{3 and the} like).

Further, as the organic solvent for the back coat paint, ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate and glycol monoethyl ether acetate are used. , Glycol dimethyl ether, glycol monoethyl ether,
Glycol ether solvent such as dioxane, benzene,
Aromatic hydrocarbon solvent such as toluene and xylene, Aliphatic hydrocarbon solvent such as hexane and heptane, Chlorinated hydrocarbon such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin and dichlorobenzene A general-purpose solvent such as a system solvent can be used.

A lubricant may be used in combination with the above-mentioned back coat layer.
In this case, there is a method of internally adding a lubricant into the back coat layer or a method of depositing a lubricant on the back coat layer. In any case, conventionally known lubricants such as fatty acids, fatty acid esters, fatty acid amides, metal soaps, aliphatic alcohols, paraffins, and silicones can be used as the above lubricants.

To give an example of these lubricants, firstly, as fatty acids,
Saturated or unsaturated fatty acids having 12 or more carbon atoms such as lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, linoleic acid and linolenic acid can be used.

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

Examples of the fatty acid amide 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, methylenebisstearic acid amide, and ethylenebisstearic acid amide. Can be used.

As the metal soap, Zn, Pb, Ni, Co, Fe, A of the above fatty acids can be used.
Salts with l, Mg, Sr, Cu, etc., or sulfonic acids such as lauryl sulfonic acid, palmityl sulfonic acid, myristyl sulfonic acid, stearyl sulfonic acid, behenyl sulfonic acid, oleyl sulfonic acid, linole sulfonic acid, linolene sulfonic acid Salts with the above metals can be used.

As the aliphatic alcohol, cetyl alcohol, stearyl alcohol and the like can be used.

Saturated hydrocarbons such as n-nonadecane, n-tridecane, and n-docosane can be used as the parisine.

As the silicone, a polysiloxane in which hydrogen is partially substituted with an alkyl group or a phenyl group, and those obtained by modifying them with a fatty acid, an aliphatic alcohol, a fatty acid amide, or the like can be used.

Furthermore, a lubricant containing a dicarboxylic acid fluorinated alkyl ester similar to the lubricant layer attached to the surface of the magnetic layer may be used.

[Function] The lubricant layer containing the fluorinated alkyl dicarboxylic acid adheres to the ferromagnetic metal thin film and exerts a good lubricating effect to reduce the friction coefficient. Particularly, the dicarboxylic acid fluorinated alkyl ester exhibits a good lubricating effect even at a low temperature.

〔Example〕

Hereinafter, specific examples of the present invention will be described.
The present invention is not limited to these examples.

Experimental Example 1. A dicarboxylic acid fluorinated alkyl monoester shown in Table 1 was synthesized, and a magnetic tape was prepared using this as a lubricant.

Example 1. Co was deposited on a 14 μm-thick polyethylene terephthalate film by oblique vapor deposition to form a ferromagnetic metal thin film having a film thickness of 1000 Å.

Next, a solution prepared by diluting the dicarboxylic acid fluorinated alkyl monoester shown in Table 1 (Compound 1 in Table 1) into Freon at a concentration of 0.05% by weight to Freon is applied to the surface of the ferromagnetic metal thin film at a coating amount of 10 mg / m 2. ^It was applied so that it would be ^2, and cut into a width of 8 mm to prepare a sample tape.

Examples 2 to 6 Compounds 2 to 6 shown in Table 1 above were used as dicarboxylic acid fluorinated alkyl monoesters, and others were used in Example 1
A sample tape was produced in the same manner as described above.

With respect to each of the prepared sample tapes, the dynamic friction coefficient and the shuttle durability under the conditions of a temperature of 25 ° C., a relative humidity (RH) of 50%, and −5 ° C. were measured. This dynamic friction coefficient uses a stainless steel (SUS304) guide pin,
The test was conducted with a constant tension and sent at a speed of 5 mm / sec. Also, the shuttle durability is 2 at a time.
The shuttle was run for 1 minute and evaluated by the number of shuttles until the output decreased by -3dB. For the still durability, the decay time of the output to −3 dB in the pause state was evaluated. In addition, as Comparative Example 1, a blank tape on which no lubricant was applied was measured. The results are shown in Table 2.

Experimental Example 2. A dicarboxylic acid fluorinated alkyl ester having a perfluoroalkyl group at one ester portion shown in Table 3 was synthesized, and a magnetic tape was prepared using this as a lubricant.

Example 7. Co was deposited on a 14 μm-thick polyethylene terephthalate film by the oblique deposition method to form a ferromagnetic metal thin film having a film thickness of 1000 Å.

Next, on the surface of the ferromagnetic metal thin film, a dicarboxylic acid fluorinated alkyl ester having a perfluoroalkyl group at one ester portion shown in Table 3 (Compound 7 in Table 3)
The solution is diluted with Freon at a concentration of 0.05% by weight.
It was applied so as to have a concentration of 10 mg / m ² and cut into a width of 8 mm to prepare a sample tape.

Examples 8 to 13 Compounds 8 to 13 shown in Table 3 above were used as the dicarboxylic acid fluorinated alkyl ester having a perfluoroalkyl group on one ester part, and the other procedure was carried out in the same manner as in Example 7. A sample tape was prepared.

With respect to each of the prepared sample tapes, the dynamic friction coefficient and the shuttle durability under the conditions of a temperature of 25 ° C., a relative humidity (RH) of 50%, and −5 ° C. were measured. This dynamic friction member
This is a test using a guide pin made of stainless steel (SUS304) with a constant tension and a speed of 5 mm / sec. Further, the shuttle durability was evaluated by the number of shuttles until the output decreased by -3 dB after the shuttle traveled for 2 minutes each time. For the still durability, the decay time of the output to −3 dB in the pause state was evaluated. In addition, as Comparative Example 2, a blank tape on which no lubricant was applied was also measured. The results are shown in Table 4.

Experimental Example 3. A dicarboxylic acid fluorinated alkyl diester shown in Table 5 was synthesized, and a magnetic tape was prepared by using this as a lubricant.

Example 14. Co was deposited on a 14 μm-thick polyethylene terephthalate film by oblique vapor deposition to form a ferromagnetic metal thin film having a film thickness of 1000 Å.

Next, on the surface of this ferromagnetic metal thin film, dicarboxylic acid fluorinated alkyl diesters shown in Table 5 (compounds in Table 5
A solution prepared by diluting 14) with Freon at a concentration of 0.05% by weight was applied so that the applied amount was 10 mg / m ^2, and cut into 8 mm width to prepare a sample tape.

Example 14 to Example 22 Sample tapes were prepared in the same manner as in Example 14 except that Compound 14 to Compound 22 shown in Table 5 above were used as the dicarboxylic acid fluorinated alkyl diester.

With respect to each of the prepared sample tapes, the dynamic friction coefficient and the shuttle durability under the conditions of a temperature of 25 ° C., a relative humidity (RH) of 50%, and −5 ° C. were measured. This dynamic friction coefficient uses a stainless steel (SUS304) guide pin,
The test was conducted with a constant tension and sent at a speed of 5 mm / sec. Also, the shuttle durability is 2 at a time.
The shuttle was run for 1 minute and evaluated by the number of shuttles until the output decreased by -3dB. For the still durability, the decay time of the output to −3 dB in the pause state was evaluated. In addition, as Comparative Example 3, a blank tape on which no lubricant was applied was measured. The results are shown in Table 6.

As is clear from Tables 2, 4, and 6 above,
In each of the examples to which the present invention was applied, the coefficient of dynamic friction was small under each condition, running was extremely stable, and no damage was observed on the tape surface even after 100 round trips. Also,
Durability was also extremely good, and output did not decrease by -3 dB even after 150 shuttle runs. On the other hand, in the tapes of Comparative Examples 1 to 3 having no lubricant layer, the coefficient of friction increased as the number of times of reciprocal running increased, running was unstable, and tape friction was observed, and durability was improved. Was also bad.

〔The invention's effect〕

As is clear from the above description, in the present invention, since the dicarboxylic acid fluorinated alkyl ester is used as the lubricant of the ferromagnetic metal thin film type magnetic recording medium,
The dynamic friction coefficient can be reduced under any temperature condition, and a magnetic recording medium excellent in running stability and wear resistance can be obtained.

In particular, since the fluorinated alkyl dicarboxylic acid ester has a low freezing point, it is highly effective when used at low temperatures.

Claims (1)

[Claims] 1. A ferromagnetic metal thin film is formed on a non-magnetic support, and the following formulas (I) (II) (II) are formed on the ferromagnetic metal thin film.
A magnetic recording medium coated with the dicarboxylic acid fluorinated alkyl ester as described in any of I). (However, in the formula, R represents a hydrocarbon group having 1 to 25 carbon atoms, and n
≧ 3 and 0 ≦ m ≦ 5. ) (However, in the formula, R represents a hydrocarbon group, and n ≧ 3, 0 ≦ m ≦
It is 5. ) (However, in the formula, R and R ′ represent a hydrocarbon group, and n ≧ 3,
0 ≦ m ≦ 5. )