JPS63813A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having excellent runnability, wear resistance and durability by providing a rust preventive agent layer consisting of a heterocyclic compd. contg. nitrogen atoms and lubricating agent layer contg. a perfluoroalkyl carboxylate on a thin ferromagnetic metallic film. CONSTITUTION:The rust preventive agent (e.g: 2-aminobenzimidazole) essentially consisting of the heterocyclic compd. contg. the nitrogen atoms is diluted with a solvent of 1 acetone: 1 ethyl ether and such soln. is coated at 10mg/m<2> coated amt. on the thin ferromagnetic metallic film 2 of 1,000Angstrom film thickness formed by depositing Co on a PE terephthalate film 1 having 14mum thickness, by which the rust preventive agent layer 3 is formed on said film. The lubricating agent layer 4 formed by dissolving the perfluoroalkyl carboxylate (e.g.: isostearyl ester of nonadecafluorodecanic acid) with the solvent of 1 acetone: 1 ethyl ether, coating the soln. at 10mg/m<2> on said layer and drying the coating is laminated on said layer, by which the magnetic recording medium is manufactured.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a so-called magnetic layer in which a ferromagnetic metal thin film is formed as a magnetic layer on a non-magnetic support by vacuum thin film forming techniques such as vacuum Geisha and sputtering. This relates to a strong (d) metal thin film type magnetic recording medium.

[5 points of the invention] The present invention provides a magnetic recording medium in which a ferromagnetic metal thin film is formed as a magnetic layer on a non-magnetic support, in which a heterocyclic ring containing a nitrogen atom is formed on the ferromagnetic metal thin film as the magnetic layer. Excellent runnability under all usage conditions by applying a rust preventive layer mainly composed of a compound and a lubricant layer containing a perfluoroalkyl carboxylic acid ester in this order.

The object of the present invention is to provide a magnetic recording medium that exhibits wear resistance, durability, and has good corrosion resistance.

[Prior Art] Conventionally, as a magnetic recording medium, r
r-FezO containing Fe 2031 Go =
.

Fe, 04. Feloir-Fez containing co
Non-magnetic materials such as ferrolide compounds of o, 3 and Fe30a, bertolide compounds containing Co, oxide ferromagnetic powders such as CrO2, or alloy magnetic powders mainly composed of Fe, Co, Ni, etc. Coated magnetic recording media are widely used, which are produced by applying and drying a magnetic paint dispersed in an organic binder such as a vinyl chloride-vinyl acetate copolymer, polyester resin, or polyurethane resin.

On the other hand, with the increasing demand for high-density magnetic recording, ferromagnetic metal materials such as co-Ni alloys can be made into polyester by plating or vacuum thin film formation technology (vacuum thin deposition method, sputtering method, ion blating 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 is attracting attention. This ferromagnetic metal ijl film type magnetic recording medium not only has excellent coercive force and squareness ratio, and has excellent electromagnetic conversion characteristics at short wavelengths, but also has the ability to make the magnetic layer extremely thin, making it possible to record Jiff It has a number of advantages, including a significantly small loss of one member in the thickness during playback and reproduction, and the ability to increase the packing density of the magnetic material because there is no need to mix a non-magnetic binder into the magnetic layer. ing.

However, in the @magnetic metal thin film type magnetic recording medium described above, the surface smoothness of the magnetic layer is extremely good, so the effective contact area is large, and adhesion phenomena (so-called sticking) are likely to occur. It has many drawbacks in terms of durability, running performance, etc., such as a large Fi! coefficient of friction, and its improvement has become a major issue.

- In general, a magnetic recording medium is subjected to high-speed relative slow movement with a magnetic head during the recording and reproducing process of magnetic signals, and during this time, the medium must run smoothly and stably. Further, it is better to minimize wear and damage caused by contact with the magnetic head.

Alternatively, in ferromagnetic metal thin film type magnetic recording media, the magnetic layer is composed of a metal material, so during storage, especially when exposed to high temperatures or high temperatures, the surface of the magnetic layer tends to corrode. There were problems such as saturation magnetization, coercive force, etc. deteriorating orally.

[Problem that the invention seeks to solve]

As described above, the above-mentioned ferromagnetic metal thin film type magnetic recording media has many problems in practical properties such as runnability, durability, and corrosion resistance.
Therefore, attempts have been made to improve this by applying lubricants, rust preventives, etc.

However, these conventional attempts are still far from satisfactory.For example, the operating temperature range of conventionally widely used lubricants is limited, especially at low temperatures such as O to -5℃. There is a problem in that many of them are solid or frozen, and their lubricating effect cannot be fully exerted.

The present invention aims to further improve such practical characteristics, and has excellent running properties, durability, and corrosion resistance.
The object of the present invention is to provide a magnetic recording medium that maintains these practical characteristics even under a wide range of operating temperatures.

[Means for solving problems]

The inventors of the present invention have conducted extensive research to achieve the above objectives, and have found that perfluoroalkylcarboxylic acid esters exhibit excellent lubricity over a wide temperature range, and that heterocyclic compounds containing nitrogen atoms It is effective in improving corrosion resistance, and furthermore, when a rust preventive layer is first deposited on a ferromagnetic metal thin film and a lubricant layer is deposited on top of that, the rust preventive layer and lubricant layer are They discovered that the method works effectively and completed the present invention.

That is, in the magnetic recording medium of the present invention, a ferromagnetic metal thin film is formed on a nonmagnetic support, and a rust preventive layer containing a nitrogen atom-containing heterocyclic compound as a main component and a perfluorinated metal thin film are formed on the ferromagnetic metal thin film. It is characterized in that a lubricant layer containing an alkyl carboxylic acid ester is deposited in this order.

In the magnetic recording medium of the present invention, the perfluoroalkyl carboxylic acid ester used as the lubricant component of the lubricant layer has the general formula % () (where X is a hydrogen atom, a fluorine atom, or both and n≧6, m≦20+1, a≧8, b≦22+1).

This perfluoroalkylcarboxylic acid ester is obtained by esterifying a perfluoroalkylcarboxylic acid that is solid at room temperature, lowering the melting point and adding the effect of an alcohol moiety, thereby extending the lubricating effect to a low temperature range.

In the above general formula (2), the aliphatic hydrocarbon group represented by C, teeth,
The above purpose can be achieved by using a linear alkyl group with less than 18 carbon atoms, or an aliphatic hydrocarbon group with a double bond or with different techniques when the number of carbon atoms is more than 18. Ta. Further, the aliphatic hydrocarbon group may be a fluorine-containing aliphatic hydrocarbon group, and therefore,
In the formula, X may be not only a hydrogen atom but also a fluorine atom, or both a hydrogen atom and a fluorine atom.

On the other hand, the carbon number n of the perfluoroalkyl carboxylic acid moiety is preferably 6 or more. If the carbon number n is less than 6, the lubricity will be insufficient.

However, if the carbon number n is too large, it will solidify in a low temperature range, so in practice it is preferable to keep n≦10.

The perfluoroalkyl carboxylic acid ester is a perfluorocarboxylic acid represented by the general formula % (in the formula, n is an integer of 6 or more, and m is an integer of 2n+1 or less); -i2C,Xb
O1+ ... (III) (X in the formula is a hydrogen atom, a fluorine atom, or both,
a is an integer of 8 or more, and b is an integer of 2a+1 or less. ) The reaction formula that can be synthesized by reacting alcohols represented by the following in approximately equimolar amounts is as follows.

C, F-COOH+ C, However, it may be used in combination with a conventionally known lubricant to further expand the operating temperature range.

The lubricants used include fatty acids or their metal salts;
Fatty acid amide, fatty acid ester, fatty alcohol or its alkoxide, fatty amine, polyhydric alcohol,
Sorbitan ester, manniratan ester, sulfurized fatty acid, aliphatic mercaptan, modified silicone oil, perfluoroalkyl ethylene oxide, perfluoropolyethers, higher alkyl sulfonic acid or its metal salt, perfluoroalkyl sulfonic acid or its ammonium salt, or its Examples include metal salts, perfluoroalkylcarboxylic acids or metal salts thereof, and the like.

Furthermore, in order to cope with more severe usage conditions and maintain the lubricating effect, the weight ratio is 30=70 to 70:30.
An extreme pressure agent may be used in combination at a certain mixing ratio.

When the above-mentioned extreme pressure agent makes partial metal contact in the boundary lubrication pH range, it reacts with the metal surface due to the accompanying frictional heat, forming a reaction product film to prevent friction and wear. Known examples include phosphorus-based extreme-pressure agents, sulfur-based extreme-pressure agents, halogen-based extreme-pressure agents, organometallic-based extreme-pressure agents, m-mold extreme-pressure agents, and the like.

Specifically, examples of the phosphorus extreme pressure agent include tributyl phosphate, trioctyl phosphate, tri-2-ethylhexyl phosphate, trilauryl phosphate, and trioleyl phosphate. Phosphate esters such as dibutyl phosphate, dioctyl phosphate, di-2-ethylhexyl phosphate, dilauryl phosphate, dioleyl phosphate, tributyl phosphite, trioctyl phosphite, tri-2-ethylhexyl phosphite, trilauryl phosphite , trioleylphosphite, dibutyl phosphite, phosphite esters such as dioctyl phosphite, di-2-ethylhexyl phosphite, dilauryl phosphite, dioleyl phosphite, and dibutyl phosphate butylamine salts.

Dibutylphosphate octylamine salt, dibutylphosphate stearylamine salt, dibutylphosphate butylamine salt, dioctylphosphneetooctylamine salt, dioctylphosphate laurylamine salt, dioctylphosphate stearylamine salt, di-2-ethylhexylphosphate butylamine salt, di-2-ethyl Hexylphosphate butylamine salt, di-2-ethylhexylphosphate laurylamine salt, di-2-ethylhexylphosphate stearylamine salt, dilaurylphosphate butylamine salt.

dilauryl phosphate octylamine salt, dilauryl phosphate traurylamine salt, dilauryl phosphate stearylamine salt, dioleyl phosphate butylamine salt, dioleyl phosphate octylamine salt,
Examples include phosphate ester amine salts such as dioleyl phosphate lauryl amine salt and dioleyl phosphate stearyl amine salt.

The above-mentioned sulfur-based extreme pressure agents include mineral oils with unsaturated bonds such as sulfurized whale oil and sulfurized dipentene, sulfurized oils and fats produced by adding sulfur to fats and oils and fatty acids, and heating them, dibenzyl disulfide, and disulfide. diphenyl, di-t disulfide
-butyl, di-5ec-butyl disulfide, di-n- disulfide
Dithylphides such as butyl, di-L-octyl disulfide, diethyl disulfide, hensyl sulfide, diphenyl sulfide, divinyl sulfide, dimenal sulfide, diethyl sulfide, di-sulfide [
-butyl, di-sec sulfide -butyl 5 monosulfides such as di-n-butyl sulfide, polysulfides such as dimethyl trisulfide, di-t-butyl trisulfide, di-t-nonyl polysulfide, olefin polysulfide, - general formula Examples include thiocarbonates represented by the formula % (in the formula, R represents a hydrocarbon group), 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, benzyl bromide, hensyl iodide, allyl iodide, butyl iodide, octadecyl iodide, Iodine compounds such as isochlorohexyl chloride, hexachloroethane, monochloroethane.

Examples include chlorine compounds such as chlorinated paraffin, chlorinated diphenyl, chlorinated fats and oils, methyl trichlorostearate, pentachloropentadienoic acid, esters of hexachloronaphthenic acid compounds, and imide derivatives of hexachloronaphthenic acid compounds.

Examples of the organometallic extreme pressure agents include zinc diisobutyldithiophosphate, zinc isobutylpentyldithiophosphate, isopropyl-1-methylbutyldithiophosphate, zinc isobutylnonylphenyldithiophosphate, isobutylheptylphenyldithiophosphate, and diheptylphenyldithiophosphate. , zinc dinonylphenyl dithiophosphate, thiophosphates such as molybdenum dithiophosphate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc ethylphenyldithiocarbamate, zinc dihendyldithiorubamate, dimethyldithiocarbamic acid Examples include thiocarbamates such as zinc, dimethyldithiocarbamin-coated copper, iron dimethyldithiocarbamate, selenium diethyldithiocarbamate, and silver diethyldithiocarbamate, and metal alkyldithiocarbamates such as molybdenum and antimony.

Examples of the composite extreme pressure agent include dialkylthiophosphate amines such as di-2-ethylhexylthiophosphate amine, propyl chloride, propyl bromide,
In addition to phosphoric acid esters of alkyl halides such as propyl iodide, butyl chloride, butyl bromide, butyl iodide, chloronaphsanthate, etc., -M formula % formula % R 8R (However, , thiophosphates represented by the general formula (wherein R represents a hydrogen atom, an alkyl group, an alkenyl group, or an aryl group); The thiophosphites represented by (representing a group) are highly effective.

The above-mentioned extreme pressure agents may be used alone, but it is also possible to use a mixture of two or more types.

- On the other hand, in the magnetic recording medium of the present invention, the nitrogen atom-containing heterocyclic compound used as the rust preventive agent in the rust preventive layer is very effective in improving the corrosion resistance of the ferromagnetic metal film, and therefore, Coupled with the lubricating action of the lubricant containing the perfluoroalkyl carboxylic acid ester, the durability of the magnetic recording medium can be improved.

Examples of usable heterocyclic compounds containing a nitrogen atom include acridine, 2.2',2''-terpyridylneocuproine, 2.2°-dipyridylhenzotriazole, 5-methylhencytriazole, and bathofenand. Lorin, 1.1
In addition to 0-phenanthroline, aldehyde collidine, hensylpyridine, phenylpyridine, quinazoline, 2-heptadecyl imidazur, etc., compounds having a phenolic hydroxyl group, such as 4-(2-pyridylazo)-resorcin 1-(2 Compounds having carboxyl groups such as -pyridylazo)-2-naphthol, 4-quinolitool, 4-methyl-2-quinolitool, 8-quinolitool, quinolinediol, such as kynurenic acid, acridic acid, atophane.

kirnadic acid, cinchoninic acid, isonicotinic acid.

2. Compounds having an amino group or imino group such as 5-pyridinedicarboxylic acid and quinic acid, such as 2-aminobenzimidazole, 5-amino-IH-tetrazole, 5-
Amino-L H-1,2,4-triazole. Compounds having a carbonyl group such as adenine, guanine, luminol, 2-hydrazinoquinoline, thiamine, etc., such as riboflavin, theobromine.

Allantoin, alloxan, 2-thiobarbic acid,
Bioluric acid 5 isatin, hydantoin, thymine, barbituric acid, orotic acid, uracil 5 scunnimide,
Examples include creatinine and 2-pyrrolidone.

The above-mentioned nitrogen atom-containing heterocyclic compound may be used alone as a rust preventive agent, or may be used in combination with a conventionally known rust preventive agent. Usable rust preventives include those normally used as rust preventive agents for this type of magnetic recording media.
For example, phenols, naphthols, quinones, diaryl ketones, heterocyclic compounds containing an oxygen atom, heterocyclic compounds containing a sulfur atom, compounds having a mercapto group, thiocarboxylic acids or salts thereof,
Examples include thiazole compounds.

In the magnetic recording medium of the present invention, as shown in FIG. After applying the rust preventive layer (3) containing the nitrogen atom-containing heterocyclic compound as a main component, the lubricant N (4) containing the perfluoroalkyl carboxylic acid ester is applied thereon. When the rust preventive layer (3) and the lubricant layer (4) are applied as two or more layers in this manner, a more excellent effect is exhibited than when a mixture of these layers is applied.

When coating in two layers like this, the above rust preventive layer (
3) Alternatively, the coating amount of the lubricant layer (4) is 0.5 mir/rl to IOOmg/n(
It is preferable that it is, and it is more preferable that it is 1 stroke/durability to 20 cm/%. If the amount applied is too small, the effects of improving corrosion resistance, reducing the coefficient of friction, improving wear resistance, runnability, and durability will be insufficient. On the other hand, if the amount is too large, the sliding member and the ferromagnetic metal thin film will not be effective. A sticking phenomenon occurs between the wheels, which actually worsens the running performance.

As for the coating method, after dissolving the above-mentioned nitrogen atom-containing heterocyclic compound or perfluoroalkyl carboxylic acid ester in a medium, the coating may be applied using a conventional coating method such as roll coating, spray coating, or spin cord dipping. .

The magnetic recording medium to which the present invention is applied is a non-magnetic support (1
), on which a ferromagnetic metal thin film (2) is provided as a magnetic layer, but here the material of the non-magnetic support (1) is:
Polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose triacetate, cellulose diacetate, and cellulose acetate butyrate,
Examples include vinyl resins such as polyvinyl chloride and polyvinylidene chloride, plastics such as polycarbonate 1 polyimide and polyamideimide, light metals such as aluminum alloys and titanium alloys, and ceramics such as alumina glass. The nonmagnetic support (1) may be in the form of a film, sheet, disk, or card.

Any drum or the like may be used.

The surface roughness of the non-magnetic support (1) may be controlled by forming one or more types of protrusions such as mountain-like protrusions or wrinkle-like protrusions on the surface of the non-magnetic support (1).

For example, the above-mentioned mountain-like protrusions have a particle size of 5 when forming a polymer film.
It is formed by internally adding Ja-free fine particles of about 0.00 to 3000, and the height from the surface of the polymer film is 100.
~1000 people, density approximately IXlO'~10X
IO'pieces/1m''.The inorganic fine particles used to form the Yamabushi projections include calcium carbonate (C
aCOa), silica, alumina, etc. are suitable.

The wrinkle-like protrusions are undulations formed by applying and drying a dilute yi solution of resin using a specific mixed solvent, for example, and the height thereof is 0.01 to 10 μm, preferably 0.03 to 0.0 μm. .5 μm, the shortest distance between protrusions is 0.1-2
It is set to 0 μm. Examples of resins used to form these wrinkle-like projections include saturated polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyamides, polystyrene, polycarbonates, polyacrylates, polysulfones, polyethersulfones, polyvinyl chloride, polyvinylidene chloride, and polyvinyl butyral. , polyphenylene oxide, phenoxy resin, etc.,
Mixtures or copolymers with soluble solvents are suitable. Then, a solvent that is a poor solvent for the resin and has a boiling point higher than the good solvent is added in an amount of 10 to 100 times the amount of the resin to a solution in which these resins are dissolved in the good solvent at a resin concentration of 1 to 100 ppm. The solution was
By coating and drying on the surface of a polymer film, giN having extremely 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 semispherical shape. The height of this granular protrusion is
50-500 people, density 1x106-50XIO' pieces/
Ryu 2 level.

At least one type of these protrusions is attached to a non-magnetic support (1).
If formed on the base film with ridges, the surface properties of the ferromagnetic metal thin film (2), which is the magnetic layer, can be controlled, but the effect is enhanced by combining two or more types. By forming protrusions and lump-like protrusions, durability and runnability can be improved by scratching.

In this case, the overall height of the protrusion is 100 to 200
Preferably within the range of 0 people, the density is 1m”
It is preferable that the average number of particles per unit is 1X10' to 1X10'.

Further, the ferromagnetic metal thin film (2), which is the magnetic layer, is formed as a continuous film by a vacuum thin film forming technique such as a vacuum evaporation method, an ion blasting method, or a sputtering method.

In the vacuum evaporation method, a ferromagnetic metal material is evaporated by resistance heating, high frequency heating, electron beam heating, etc. under a vacuum of 10-' to 1 O-'' Torr, and the evaporated metal (ferromagnetic metal material) is deposited on a disk substrate. -i
In order to obtain a high coercive force, an oblique deposition method is employed in which the ferromagnetic metal material is deposited obliquely to the substrate. Alternatively, it also includes those in which the vapor deposition is performed in an oxygen atmosphere in order to obtain higher coercive force.

The above ion blating method is also a type of vacuum τ deposition method, in which DC glow discharge and RF glow discharge are caused in an inert gas atmosphere of 10-4 to 10-' Torr, and the above-mentioned ferromagnetic metal material is It is evaporated.

The above sputtering method involves generating glow discharge in an atmosphere mainly composed of argon gas at 101 to 10 Torr, and using the generated argon gas ions to knock out atoms on the target surface. 2-stroke, 3-stroke bafta method, high frequency sputtering method,
Alternatively, there is a magnetron sputtering method using magnetron discharge.

When using this sputtering method, C" and W.

A base film such as (2) may be formed in advance.

In any of the above methods, Bi, Sb, Pb, Sn, Ga, and In are preliminarily deposited on the substrate.

By pre-depositing a base metal layer such as Cd, Ge, Si, TI, etc., and depositing the film in a direction perpendicular to the substrate surface, it is possible to achieve excellent in-plane isotropy without magnetic anisotropy orientation. It is possible to form a magnetic layer, and is suitable for use in, for example, magnetic disks.

Using this vacuum thin film formation technology, a ferromagnetic metal thin film (2
), the ferromagnetic metal materials used include metals such as Fe, Co, and Ni, as well as Go-Ni alloy,
Co-Pt alloy, Co-Ni-Pt alloy, Fe-Co alloy, Fe-Ni alloy, Fe-Co-Ni alloy, Fe-C
o-B alloy, C.

Examples include -Ni-Fe-8 alloy, Co-Cr alloy, and those containing metals such as Cr and A1. In particular, when a Co--Cr alloy is used, a perpendicularly magnetized film is formed.

The thickness of the magnetic layer formed is approximately 0.04 to 1 μm.

In addition, as shown in FIG. 2, a so-called Banokko layer (5) is formed on the surface of the non-magnetic support (1) opposite to the surface on which the ferromagnetic gold layer (2) is provided. may be formed. The back coat layer (5) is formed by applying a back coat paint in which a binder resin and a powder component are mixed and dispersed in an organic solvent to the surface of the nonmagnetic support (1).

Examples of the binder resin used in the back coat paint include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, and acrylic ester-acrylonitrile copolymer. copolymer, thermoplastic polyurethane elastomer, borif, vinyl chloride, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer,
Synthetic rubber resins such as polyamide resins, polyvinyl butyral, cellulose derivatives, polyester resins, and polybutadiene, phenolic resins, epoxy resins, polyurethane curable resins, melamine resins, alkylene resins, silicone resins, acrylic reaction resins, epoxy-polyamides resins, nitrocellulose-melamine resins, mixtures of high molecular weight polyester resins and isocyanate prepolymers, mixtures of methacrylate copolymers and diisocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, low Examples include mixtures of molecular weight glycol/high molecular weight diol/triphenylmethane triisocyanate, polyamine resins, and mixtures thereof.

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

Specifically, SOJ, O5OxM, C00M
, a polyurethane resin into which a hydrophilic polar group selected from P(OH)2 (wherein M represents a hydrogen atom or an alkali metal, and M' represents a hydrogen atom and an alkali metal or a hydrocarbon group); Polyester resin, vinyl chloride
Vinyl acetate copolymers, vinylidene chloride copolymers, acrylic ester copolymers, butadiene copolymers, etc. can be used.

As a method for introducing the above-mentioned hydrophilic polar group, (various methods can be considered depending on the type of M resin, for example, to introduce the above-mentioned hydrophilic polar group into polyurethane resin or polyester resin, the following method is used. According to

(11 A method in which the above-mentioned water-based polar group is introduced in advance into a dibasic acid, polyol, etc. that is a raw material for polyurethane or polyester.

(2) A method in which an OH group is left at the terminal or side chain, and this OH group is modified with a compound having a hydrophilic polar group.

In the case of method (2), a compound containing a hydrophilic polar group and a halogen (e.g. chlorine) is used as a raw material, and a polyfunctional polyol is used as a raw material, and an OH group remains at the end or side chain of the polymer chain. Polyurethane resin or polyester resin is dissolved in a solvent such as dimethylformamide or dimethyl sulfoxide in which both components are soluble, and amines such as pyridine, picoline, triethylamine, and epoxy compounds such as ethylene oxide and propylene oxide are dehydrochlorinated. OH in the presence of agent
A method of introducing a hydrophilic polar group through a dehydrochlorination reaction between the group and chlorine.

[21-2 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 OHI remains at the end or side chain of a polymer chain via a diisoanate compound.

There is.

In order to introduce a hydrophilic polar group into the copolymer-based binder resin, (3) a method of using a compound having a hydrophilic polar group and a copolymerizable double bond as a copolymerizable monomer.

(4) As a copolymerizable monomer, use a compound containing active hydrogen and a copolymerizable double bond, introduce the above active hydrogen into the side chain of the copolymer, and combine it with the current aqueous polar group and the above active hydrogen. A method of modification with a compound containing a reactive group.

(5) As a copolymerization monomer, use a compound having a group that can react with active hydrogen and a double bond that can be copolymerized, and introduce the group that can react with active hydrogen into the side chain of the copolymer. , a method of modifying with a hydrophilic polar group and a compound having the above-mentioned active hydrogen.

etc.

On the other hand, the above-mentioned powder components include carbon-based fine powders that impart conductivity (e.g., furnace carbon, channel carbon, acetylene carbon, thermal carbon, lamp carbon, etc., among which furnace carbon and thermal carbon are used). ), inorganic pigments (added to control surface roughness and improve durability),
+ CrJx + T+ Ox + ZnO, Si
o+5iOtlSiOz ・2HzO,Alz(h −
2SiCh' 2Hz0, 3Mg0-4SiOz
・HtO, MgCO5・Mg(Oll)z + 3Hz
O, AlzOt, CaCO3゜hgco, 5b2o,
etc.).

Furthermore, as the organic solvent for the above-mentioned back coat paint,
Ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate,
Ethyl acetate, butyl acetate.

Ester solvents such as ethyl lactate and glycol monoethyl acetate, glycol dimethyl ether, and glycol monoethyl ether. Glycol ether solvents such as dioxane, aromatic hydrocarbon solvents such as Hensen, toluene, dixolene, aliphatic hydrocarbon solvents such as hexane and heptane, methylene chloride, ethylene chloride,
Carbon tetrachloride, chloroform, ethylene chlorohydrin,
A general-purpose 7-volume agent can be used, such as a chlorinated hydrocarbon-based agent such as dichlorobenzene.

A lubricant may be used in combination with the above-mentioned back coat layer (5). In this case, there is a method of internally adding a lubricant to the back coat layer (5) or a method of depositing a lubricant on the hack coat layer (5). In any case, as the lubricant, conventionally well-known lubricants such as fatty acids, fatty acid esters, fatty acid amides, metal soaps, aliphatic alcohols, paraffins, and soricones can be used.

Examples of these lubricants include fatty acids such as saturated fatty acids having 12 or more carbon atoms, such as lauric acid, myristic acid, valmitic acid, stearic acid, hehenic acid, oleic acid, linoleic acid, and lyuronic acid, or unsaturated fatty acids. Fatty acids 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, valmitic acid amide, stearic acid amide, hehenic acid amide, oleic acid amide,
linoleic acid amide, methylene bisstearic acid amide,
Ethylene bisstearamide, etc. can be used.

The metal soaps include the aforementioned fatty acids Zn, Pb, and N.
i.

Co, Fe, A1. Salts with Mg, Sr, Cu, etc., or sulfonic acids such as lauryl sulfonic acid, palmitylsulfonic acid, myristylsulfonic acid, stearylsulfonic acid, behenylsulfonic acid, oleylsulfonic acid, linolesulfonic acid, lilinsulfonic acid and the above metals. Salt, etc. can be used.

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

Saturated hydrocarbons such as n-nonadecane, n-tridecane, and n-tocosan can be used as the paraffin.

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.

Furthermore, a lubricant containing the same perfluoroalkyl carboxylic acid ester as in the previous lubricant layer (4) may be used.

[Effect]

The rust preventive layer, which is mainly composed of a heterocyclic compound containing nitrogen atoms, and the lubricant layer, which contains perfluoroalkyl carboxylic acid ester, firmly adhere to the ferromagnetic metal thin film, exhibiting a good lubrication effect and reducing friction. This reduces the coefficient and prevents rust from occurring in ferromagnetic metal thin films. In particular, perfluoroargyl carboxylic acid ester exhibits a good lubricating effect even at low temperatures, so the temperature range in which it can be used can be expanded.

〔Example〕

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

First, various perfluoroalkyl carboxylic acid esters were synthesized using the following synthesis examples.

Synthesis Example 1゜Nonadecafluorodecanoic acid isostearyl ester C1
h(Cflz)s-C)I-CHz-OCO(CFz)
8ch (CLLC) An ester reaction was carried out between isostearyl alcohol and nonadecafluorodecanoic acid in toluene using p-)luenesulfonic acid as a catalyst. That is, after heating under reflux for 1 hour, 3
Water in the solvent was removed over time, toluene was removed under reduced pressure using an evaporator, and the mixture was purified by vacuum distillation. (Isostearyl alcohol was synthesized by converting commercially available isostearic acid into n-butyl ester and then reducing it with lithium aluminum hydride.) The boiling point of the obtained fraction, p, was 140 to 145°C. , 2 mm) Ig
Met.

In addition, the product was analyzed using infrared spectroscopy (IR).

The analysis was carried out by magnetic resonance analysis (NMR) and mass spectrometry (MASS). As a result, an absorption peculiar to the CF bond was observed from 1210 to 1380 cm-', an absorption of ester at 1780 cm-', and an absorption due to the CH stretching vibration at 2910c+n-'. This structure was determined because " is observed in 765.

Synthesis Example 2゜Pentadecafluorooctanoic acid isostearyl ester CL (CI!2) a-CI-CH2-OCO (CF
z), CF1(C1+2)ACI+3 By the same method as in Synthesis Example 1 above, isostearyl alcohol and pentadecafluorooctanoic acid were added in toluene.
The reaction was carried out using p-toluenesulfonic acid as a catalyst.

b, p, 120-134℃ (0.2mmtlH)
IR1200-1400cm-'1780cm-'2920cm1M''665 Synthesis Example 3゜Pentadecafluorooctanoic acid isononyl ester (C
Hz)zC(CHt)CH(CHz)CI(tcHzQ
co(CFz)6cPs By the same method as in Synthesis Example 1 above, isononyl alcohol and pentadecafluorooctanoic acid were reacted in toluene using I)-toluenesulfonic acid as a catalyst.

b, ρ, 94℃ (0.2mmHg) IR1210~
1390cm-'1785cm-'2850-2960C+I-'M" 539 Synthesis Example 4゜Pentadecafluorooctanoic acid sulfuryl ester CH (CL) 3 (CHIC)l=c)I) 2 (CH
5Oco (CFz) 6CF3 By the same method as in Synthesis Example 1 above, lilyl alcohol and pentadecafluorooctanoic acid were reacted in toluene using p-toluenesulfonic acid as a catalyst.

b, p, 135-139℃ (0.2mmHg)I
R1210-1380C+l-'1780cm-'2850-3020cm-'M' 663 Example 1 Co was deposited on a polyethylene terephthalate film with a thickness of 4 μm by an oblique evaporation method to form a ferromagnetic metal thin film with a thickness of 1000 μm.

Next, on the surface of this ferromagnetic metal thin film, a solution prepared by diluting the rust preventive shown in Table 1 with a solvent (acetone; ethyl ether-1: l) was applied at a coating amount of 10 mg/n. Further, perfluoroalkylcarboxylic acid esters (synthesized in the previous synthesis example) shown in Table 1 were placed on this rust preventive layer in a solvent (acetone: ethyl ether = 1
The solution diluted with: 1) was applied in a coating amount of Low/rrf, and after drying, it was cut into 1/2 inch width to prepare a sample tape.

(Left below) Table 1 (A) Table 1 (B) Initial holding power (
Hc+) and saturation magnetization 1i (Is+), and 45°C.

After being left under 80% RH for one week, the coercive force (Hcz) and saturation magnetization ft (Isz) were measured, and the rate of change was determined according to the following formula. As a comparative example, the rate of change was also investigated for a blank tape to which no rust preventive was applied. The results are shown in Table 2.

Rate of change in Hc - (HC2Hc+)/llc+ X100
(X) - (Change rate of formula 21 Is = (Isz Is+)
/Is+

Next, for each sample tape produced, a temperature of 25
The dynamic g-friction coefficient and shuttle durability were measured under the following conditions: 50% relative humidity (RH), and -5°C. This coefficient of dynamic friction was determined by using a guide bottle made of stainless steel (SUS304) and applying a constant tension of -5IIIIII.
The test was carried out by feeding at a speed of /sec. In addition, the shuttle durability was evaluated by running the shuttle for 2 minutes each time, and determining the number of shuttle runs until the output decreased by 13 dB. Methyl durability was evaluated by evaluating the decay time for the output to -3 dB in a pause state. As a comparative example, a blank tape to which no lubricant was applied was also measured. The results are shown in Table 3 (A) and Table 3 (B).

(Margins below) Table 3 (A) Table 3 (B) As is clear from this table, each example of the present invention has a small dynamic friction coefficient under both normal temperature and low temperature conditions, and the running is extremely stable. Moreover, even after running back and forth 100 times, no damage was observed on the tape surface. Furthermore, the durability was extremely good, and even after 150 shuttle runs, no decrease in output by 13 dB was observed. On the other hand, in the tape of the comparative example without a lubricant layer, the friction coefficient increased as the number of reciprocating runs increased, running was unstable, tape wear was observed, and durability was poor.

〔Effect of the invention〕

As is clear from the above explanation, in the present invention, a rust preventive layer containing a nitrogen atom-containing heterocyclic compound as a soil component and a perfluoroalkyl carboxylic acid ester are provided on the surface of the thin ferromagnetic metal that is the magnetic layer. Since the lubricant layer containing
Alternatively, the lubricating effect can be further effectively increased, making it possible to significantly improve the practical characteristics, resulting in a magnetic recording medium with excellent running stability, wear resistance, and corrosion resistance.

In addition, since the pseudo-solidification temperature of perfluoroalkyl carboxylic acid ester is particularly low, the above-mentioned practical characteristics are ensured even when used at low temperatures, making it possible to expand the operating temperature range of magnetic recording media. .

[Brief explanation of the drawing]

FIG. 1 is an enlarged cross-sectional view of a main part showing an example of a magnetic recording medium to which the present invention is applied, and FIG. 2 is an enlarged cross-sectional view of a main part showing another example of the present invention. l...Nonmagnetic support 2...Ferromagnetic metal thin film 3...Rust preventive layer 4...Lubricant layer

Claims (1)

[Claims] A ferromagnetic metal thin film is formed on a non-magnetic support, and a rust preventive layer containing a nitrogen atom-containing heterocyclic compound as a main component and a lubricant layer containing a perfluoroalkyl carboxylic acid ester are formed on the ferromagnetic metal thin film. A magnetic recording medium characterized in that the following are deposited in this order.