JP2002133641A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent powder from dropping, avoid deterioration in characteristic caused by the abrasion of a head, and reduce the drop in output by a spacing loss. SOLUTION: In the magnetic recording medium 10, in which a magnetic layer 2 comprising the thin film of a ferromagnetic metal and a carbon- protecting film 3 are formed in this order on a non-magnetic base material 1, an aromatic alcohol-treated layer 4 is formed on the carbon-protecting film 3, and then a lubricant layer 5 containing a perfluoropolyether compound and an amine compound is formed on the aromatic alcohol-treated layer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a magnetic recording medium.

[0002]

2. Description of the Related Art In recent years, as the demand for high recording density and long-time recording has increased, a polyester film has been formed by plating a ferromagnetic metal material or forming a vacuum thin film (such as a vacuum evaporation method, a sputtering method, or an ion plating method). Or directly on a non-magnetic support such as a polyamide film,
A so-called metal thin film type magnetic recording medium is used in a consumer video format (8 mm Hi-8 format, DV format) or a professional video format (DVCAM).
Has been put to practical use.

[0003] A metal thin film type magnetic recording medium is excellent in coercive force, squareness ratio, etc., is excellent in electromagnetic conversion characteristics at short wavelengths, and can make the thickness of a magnetic layer extremely thin. The thickness loss at the time of reproduction is extremely small, and it is not necessary to mix a binder, which is a nonmagnetic material, in the magnetic layer, so that the packing density of the magnetic material can be increased.
It has a number of advantages.

In the age of digital information, high density magnetic recording is increasingly required, and a helical scan system using a magnetoresistive head (MR head) having higher sensitivity has been proposed.
Patent Publication 3652 discloses a metal thin film type magnetic recording medium suitable for a helical scan system.

[0005]

In the helical scan method, the magnetic layer surface and the magnetic head slide at high speed, so that the magnetic layer surface is easily damaged when the tape runs. Therefore, in order to protect the magnetic layer, a carbon protective layer and a lubricant layer are generally formed on the magnetic layer. However, if the carbon protective film and the lubricant are scraped by the magnetic head and the scraped material accumulates, a gap (spacing) occurs between the magnetic tape and the magnetic head, and a predetermined signal output is obtained. The problem (dust drop) that the worn or shaved protective layer becomes an abrasive and wears the magnetic head.

Further, in recent years, the electromagnetic conversion characteristics have been improved, and the surface properties of the magnetic layer are in the direction of being mirror-finished.
The friction between the magnetic tape and the magnetic head tends to be higher. In addition, as the recording time increases, the sliding time between the magnetic tape and the magnetic head increases, and the scanning speed tends to increase. Therefore, scraping of the magnetic recording medium of the metal magnetic thin film type is further promoted.

In order to prevent the above-described spacing loss due to powder dropping, a method of physically polishing a magnetic head by using a cleaning tape for physically polishing the magnetic head is used. However, when the magnetic head is polished by such a physical method, there is a problem that if the polishing force is too high during polishing, the magnetic head is polished more than necessary and the characteristics of the magnetic head are deteriorated. .

In particular, the characteristics of a magnetoresistive read head and an electromagnetic induction thin film head manufactured by a thin film forming technique are liable to be significantly deteriorated due to wear. Therefore, a cleaning tape cannot be used to remove the accumulated powder drop, and it is necessary to suppress the occurrence of powder drop of the magnetic tape in order to prevent the output from decreasing.

In the metal thin-film type magnetic recording medium disclosed in the above-mentioned JP-A-11-203652,
Although perfluoropolyether is used as a lubricant to be applied to the surface, there is a problem that much powder falls off, resulting in a reduction in level (output reduction) and large head wear.

The present invention has been made in view of the above problems, and excellent lubricity is maintained under various conditions of use of a magnetic recording medium compatible with a magnetoresistive read head and an electromagnetic induction type thin film magnetic head. Further, it is an object of the present invention to provide a magnetic recording medium in which the lubricating effect is maintained for a long period of time, the occurrence of powder drop is suppressed, the characteristics do not deteriorate due to head abrasion, and the output decrease due to spacing loss is small.

[0011]

A magnetic recording medium according to the present invention comprises a magnetic layer comprising a ferromagnetic metal thin film and a carbon protective film sequentially formed on a non-magnetic support. It is applied to the helical scan magnetic recording system used, has an aromatic alcohol treatment layer on the carbon protective layer, and has a carboxyl group at the terminal represented by the following [Chemical Formula 4] on the aromatic alcohol treatment layer. And a lubricant layer containing a compound of a bifunctional perfluoropolyether having the following formula and an amine.

Embedded image (However, Rf represents a perfluoropolyether chain,
R ₁ , R ₂ , R ₃ and R ₄ represent hydrogen or a hydrocarbon group. )

The magnetic recording medium of the present invention comprises a magnetic layer comprising a ferromagnetic metal thin film and a carbon protective layer sequentially formed on a non-magnetic support, and a helical scan using a magnetoresistive read head. It is applied to a magnetic recording system, and has an aromatic alcohol-treated layer on a carbon protective layer, and a perfluoro group having a terminal carboxyl group represented by the following chemical formula 5 on the aromatic alcohol-treated layer. It is assumed that a lubricant layer containing a compound of polyether and amine is formed.

Embedded image (However, Rf represents a perfluoropolyether chain,
R ₁ , R ₂ , R ₃ and R ₄ represent hydrogen or a hydrocarbon group. )

The magnetic recording medium of the present invention comprises a magnetic layer comprising a ferromagnetic metal thin film and a carbon protective layer sequentially formed on a non-magnetic support, and a helical scan using a magnetoresistive read head. The present invention is applied to a magnetic recording system, and has an aromatic alcohol-treated layer on a carbon protective layer, and a perfluoro group having a terminal carboxyl group represented by the following chemical formula 6 on the aromatic alcohol-treated layer. It is assumed that a lubricant layer containing a compound of polyether and diamine is formed.

Embedded image (Where Rf represents a perfluoropolyether chain; R represents a hydrocarbon group; R ₁ , R ₂ , R ₃ , R ₄ , R
₅ , R ₆ represents hydrogen or a hydrocarbon group. )

According to the magnetic recording medium of the present invention,
Excellent lubricity is maintained at the outermost surface, powder drop is suppressed, deterioration of electromagnetic conversion characteristics due to wear of the magnetic head is avoided, and output deterioration due to spacing loss is reduced.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The magnetic recording medium of the present invention is formed on a nonmagnetic support such as a polyethylene terephthalate film.
It has a configuration in which a magnetic layer made of a ferromagnetic metal thin film of Co or the like and a carbon protective film are sequentially formed, and is applied to a helical scan magnetic recording system using a magnetoresistive read head. Then, an aromatic alcohol-treated layer is formed on the carbon protective layer, and a lubricant layer is formed on the aromatic alcohol-treated layer. It is assumed that the lubricant is formed by applying a lubricant containing a compound of a bifunctional perfluoropolyether having a carboxyl group at a terminal and an amine as shown below.

Embedded image (However, Rf represents a perfluoropolyether chain,
R ₁ , R ₂ , R ₃ and R ₄ represent hydrogen or a hydrocarbon group. )

Further, the magnetic recording medium of the present invention is provided on a non-magnetic support such as a polyethylene terephthalate film.
A magnetic layer made of a ferromagnetic metal thin film such as O and a carbon protective layer are sequentially formed, and are applied to a helical scan magnetic recording system using a magnetoresistive read head. An aromatic alcohol-treated layer is provided on the carbon protective layer, and a lubricant layer is formed on the aromatic alcohol-treated layer. It is assumed that the lubricant is formed by applying a lubricant containing a compound of a perfluoropolyether having a group and an amine.

Embedded image (However, Rf represents a perfluoropolyether chain,
R ₁ , R ₂ , R ₃ and R ₄ represent hydrogen or a hydrocarbon group. )

Further, the magnetic recording medium of the present invention comprises a magnetic layer made of a ferromagnetic metal thin film of Co or the like and a carbon protective layer formed on a non-magnetic support such as polyethylene terephthalate in that order. It is assumed that the present invention is applied to a helical scan magnetic recording system using a reproducing head. On the carbon protective layer, an aromatic alcohol-treated layer is provided, and a lubricant layer is formed on the aromatic alcohol-treated layer. The lubricant layer is represented by the following [Chemical Formula 9].
It shall be formed by applying a lubricant containing a compound of a perfluoropolyether having a carboxyl group at a terminal and a diamine.

Embedded image (Where Rf represents a perfluoropolyether chain; R represents a hydrocarbon group; R ₁ , R ₂ , R ₃ , R ₄ , R
₅ , R ₆ represents hydrogen or a hydrocarbon group. )

Hereinafter, an embodiment of the magnetic recording medium of the present invention will be described, but the present invention is not limited to the following examples.

FIG. 1 is a schematic sectional view showing an example of the magnetic recording medium 10 of the present invention. The magnetic recording medium 10 has a magnetic layer 2 and a carbon protective layer 3 sequentially formed on a non-magnetic support 1, and has an aromatic alcohol-treated layer 4 on the carbon protective layer 3. It has a configuration in which a lubricant layer 5 is formed on the layer 4.

The material constituting the non-magnetic support 1 is as follows.
Polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, polyvinyl chloride, vinyl resins such as polyvinylidene chloride, polycarbonate, polyimide, polyamide, Plastics such as polyamide imide are exemplified.

In order to control the surface properties of the non-magnetic support 1, fine protrusions (not shown) such as fine protrusions, wrinkles, and granular protrusions can be appropriately formed on the surface.

For example, when the polymer film constituting the nonmagnetic support 1 is formed, the mountain-like projections have a particle size of 50 to 50, for example.
It can be formed by internally adding about 300 [nm] of inorganic fine particles, and the height from the surface is 10 to 100.
[Nm] and a density of about 10,000 to 100,000 [pieces / mm ² ]. Examples of the inorganic fine particles include calcium carbonate, silica, and alumina.

The wrinkle-like projections can be formed, for example, by applying a dilute solution of a resin using a specific mixed solvent on the non-magnetic support 1 and drying it. The height of the wrinkle-like projections is 0.01 to 1 [μm], preferably 0.0 to 1 [μm].
3 to 0.5 [μm], and the shortest distance between projections is 0.1 to
It is formed to about 20 [μm].

Examples of the resin for forming wrinkle-like projections include polyester such as polyethylene terephthalate and polyethylene naphthalate, polyamide, polystyrene, polycarbonate, polyacrylate, polysulfone, polyvinyl chloride, polyvinylidene chloride, polyvinyl butyral, and polyphenylene. Oxides, phenoxy resins, and other simple substances, mixtures, and copolymers can be mentioned, and those having these soluble solvents are suitable. Then, these resins are dissolved in the good solvent at a resin concentration of 1 to 10
In a solution of 00 ppm, a solvent which is a poor solvent for the resin and has a higher boiling point than
By applying and drying the solution added in an amount of about 100 times on the surface of the nonmagnetic support 1, a thin layer having very fine wrinkle-like irregularities can be formed.

The granular projections can be formed by adhering 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 5 to 50 [nm], and the density is 10
The range is preferably about 100,000 to 50,000,000 [pieces / mm ² ].

The surface property of the magnetic layer 2 can be controlled by forming at least one of the above-mentioned protrusions on the non-magnetic support 1. However, the protrusion may be formed by combining two or more kinds. Thereby, the effect can be increased. In particular, by forming wrinkle-like protrusions and granular protrusions on the nonmagnetic support 1 on which the mountain-like protrusions are formed, it is possible to improve durability and running performance.

In this case, the overall height of the projection is 1
The density is preferably in the range of 0 to 200 [nm], and the density thereof is preferably 100,000 to 10 million [pieces / mm ² ].

The magnetic layer 2 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. This vacuum deposition method is 1 × 1
The ferromagnetic metal material is evaporated under a vacuum of 0 ^-2 to 1 × 10 ^-6 [Pa] by resistance heating, high frequency heating, electron beam heating or the like, and is deposited on the non-magnetic support 1. Generally, in order to obtain a high coercive force, oblique evaporation in which the ferromagnetic metal material is obliquely evaporated on the non-magnetic support 1 is used. Further, there is included a method in which vapor deposition is performed in an oxygen atmosphere to obtain a higher coercive force.

The ion plating method is also a kind of vacuum deposition, and causes a DC glow discharge and an RF glow discharge in an inert gas atmosphere of 1 × 10 ^-2 to 1 × 10 ^-1 [Pa]. Then, the ferromagnetic metal material is evaporated.

The sputtering method is 0.1 to 10 [P
a) a glow discharge is caused in an atmosphere containing argon gas as a main component, and the generated argon gas ions strike out atoms on the target surface.
There are a three-electrode sputtering method, a high-frequency sputtering method, a magnetron sputtering method using magnetron discharge, and the like.

As a ferromagnetic metal material used when forming a metal magnetic thin film by such a vacuum thin film forming technique, in addition to metals such as Fe, Co, and Ni, a Co—Ni alloy and a Co—Pt alloy can be used. , Co-Ni-Pt alloy, Fe-C
o alloy, Fe-Ni alloy, Fe-Co-Ni alloy, Fe
-Co-B alloy, Co-Ni-Fe-B alloy, Co-C
r alloy, or an alloy containing a metal such as Pt or Al. In particular, when a Co—Cr alloy is used, a perpendicular magnetization film is formed. The thickness of the magnetic layer 2 made of a ferromagnetic metal thin film is preferably 0.01 to 1 μm.

The carbon protective layer 3 on the magnetic layer 2 can be formed by a PVD method such as sputtering or a CVD method. When the carbon protective layer 3 is formed by the CVD method, a hydrocarbon gas or a mixed gas of a hydrocarbon gas and an inert gas is introduced into a vacuum vessel, and 10 to 100 gas is introduced.
While maintaining the pressure at about [Pa], discharge is performed in a vacuum vessel to generate hydrocarbon gas plasma, and a carbon thin film is formed on the magnetic layer 2. As a discharge type,
Either the external electrode method or the internal electrode method may be used, and the discharge frequency is experimentally determined.

Further, by applying a voltage of 0 to -3 [kV] to the electrode on the base side, the hardness of the carbon protective layer 3 can be increased and the adhesion can be improved. Examples of the hydrocarbon gas include methane, ethane, propane,
Butane, pentane, hexane, heptane, octane, ethylene, acetylene, propene, butene, pentene, benzene and the like can be used.

The magnetic recording medium 10 of the present invention has an aromatic alcohol treatment layer 4 on the carbon protective layer 3. This aromatic alcohol treatment layer 4 can be formed by top-coating the following aromatic alcohol on the carbon protective layer 3.

As the aromatic alcohol, phenols, naphthols and the like can be used. Examples of the phenols include dihydric phenols, alkylphenols, and nitrosophenols.

Examples of the dihydric phenol include pure phenols such as hydroquinone, resorcinol and catechol, and alkylamino, nitro and halogeno substituted products thereof such as 2-methylhydroquinone, 4-methylresorcinol, 5-methylresorcinol and 4-methylresorcinol. Methylpyrocatechol, 2,5-dimethylhydroquinone, 4,6-dimethylresorcinol, 2,5-dimethylresorcinol, 2-isopropyl-5-methylhydroquinone,
-Tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 4-tert-butylcatechol, 2
-Aminoresorcinol, 2-resorcinol, 2,5
-Dichlorohydroxyquinone and the like.

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-te
rt-butylphenol, 2,6-di-tert-butyl-p
-Cresol, 4,4'-methylenebis-2,6-di-
tert-butylphenol, 2,6-dimethyl-4-tert
-Butylphenol, 2,4,6-tri-tert-butylphenol and the like.

As the nitrosophenol, for example, 4-
Nitroso-2-methoxy-1-phenol, 4-nitroso-2-ethoxy-1-phenol, 6-nitroso-o
-Cresol, 4-nitroso-m-cresol, o-nitrosophenol, p-nitrosophenol, 2-nitrosoresorcin, 4-nitrosoresorcin and the like.

The naphthols include α-naphthol, β-naphthol, 1,2-naphthalenediol,
1,3-naphthalene diol, 1,4-naphthalene diol, 1,5-naphthalene diol, 1,7-naphthalene diol, 1,8-naphthalene diol, 2,3-naphthalene diol, 1,4,5-naphthalene triol Naphthols such as 1,1,2,5,8-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 and the like can be mentioned.

When forming the aromatic alcohol-treated layer 4, the amount of the aromatic alcohol applied is very important. In the magnetic recording medium 10 of the present invention, the amount of the aromatic alcohol per unit area is particularly large. The amount of the bifunctional perfluoro group having a carboxyl group at the terminal represented by the above chemical formula 7 contained in the lubricant used for forming the lubricant layer 5 formed on the aromatic alcohol treatment layer 4 Compound of polyether and amine, compound of perfluoropolyether having terminal carboxyl group and amine shown in the above [Chemical Formula 8], perfluoropolyether having terminal carboxyl group shown in the above [Chemical Formula 9] and diamine It is necessary that the amount of any one of the above-mentioned compounds is not less than the coating amount per unit area.

The surface of the carbon protective layer 3 can be modified by the aromatic alcohol, and the lubricant adsorbing power can be increased. This is because the π electrons of the carbon protective layer 3 and the π electrons of the aromatic alcohol attract each other, and the hydroxyl groups in the aromatic alcohol molecules serve as adsorption sites for the lubricant.

The lubricant used when forming the lubricant layer 5 constituting the magnetic recording medium 10 of the present invention contains any one of the above chemical formulas [7], [8] and [9]. These will be described below.

The compound shown in Chemical Formula 7 applied to the lubricant layer 5 constituting the magnetic recording medium 10 of the present invention is defined as a first compound. This first compound is a compound of a bifunctional perfluoropolyether having a terminal carboxyl group and an amine. The first compound can be synthesized by, for example, mixing a bifunctional perfluoropolyether having a carboxyl group at a terminal with an amine and heating the mixture at a temperature equal to or higher than the melting point of the amine used. For example, when stearylamine is used as the amine, the mixture may be heated and mixed at 60 ° C.

Further, it can also be obtained by dissolving both in an organic solvent and then removing the solvent. When the amine is a quaternary ammonium compound, a metal salt of perfluoropolyether (eg, sodium salt) and a quaternary ammonium salt (chloride, iodide, sulfate, etc.) are mixed and extracted with an organic solvent. Can be obtained.

Here, as the bifunctional perfluoropolyether having a terminal carboxyl group used in synthesizing the first compound shown in the above [Chemical formula 7], commercially available ones can be used. For example, the following [Chemical Formula 10] is exemplified. The present invention is not limited to the following compounds.

[0046]

HOOCCF ₂ (OCF ₂ CF ₂ ) _p (OC
F ₂ ) _q OCF ₂ COOH wherein p and q in the above [Chemical Formula 10] each represent an integer of 1 or more.

The molecular weight of the bifunctional perfluoropolyether having a carboxyl group at the terminal is not particularly limited, but practically preferably about 600 to 5000, more preferably 1000 to 4000. . If the molecular weight is too large, the effect of the terminal group as an adsorptive group is diminished, and at the same time, the perfluoropolyether chain becomes large, so that it becomes difficult to dissolve in existing hydrocarbon solvents. Conversely, if the molecular weight is too small, the lubricating effect of the perfluoropolyether chain will be lost.

In the bifunctional perfluoropolyether having a carboxyl group at the terminal, the perfluoropolyether chain may be partially hydrogenated. That is, a part (50% or less) of the fluorine atoms of the perfluoropolyether chain may be replaced with a hydrogen atom. In this case, a partially hydrogenated perfluoropolyether may be used as the perfluoropolyether.

As the amine, primary amine, secondary amine
Both amines and tertiary amines can be used, and quaternary ammonium compounds can also be used. The structure of the amine to be used is also arbitrary, such as a branched structure, an isomer structure,
It can be arbitrarily selected irrespective of the alicyclic structure, molecular weight, and presence or absence of an unsaturated bond. However, the amine preferably has an alkyl group in the molecule, and particularly when the amine has an alkyl group having 10 or more carbon atoms, a high effect is obtained.

The compound represented by Chemical Formula 8 applied to the lubricant layer 5 constituting the magnetic recording medium 10 of the present invention is defined as a second compound. The second compound is a compound of a perfluoropolyether having a carboxyl group at a terminal and an amine. The second compound can be synthesized, for example, by mixing a monofunctional perfluoropolyether and an amine and heating the mixture at a temperature equal to or higher than the melting point of the amine used. For example, when stearylamine is used as the amine, the mixture may be heated and mixed at 60 ° C.

Further, it can also be obtained by dissolving both in an organic solvent and then removing the solvent. When the amine is a quaternary ammonium compound, a metal salt of perfluoropolyether (eg, sodium salt) and a quaternary ammonium salt (chloride, iodide, sulfate, etc.) are mixed and extracted with an organic solvent. Can be obtained.

Here, as the monofunctional perfluoropolyether having a carboxyl group at the terminal used for synthesizing the second compound shown in the above [Chemical formula 8], commercially available monofunctional perfluoropolyether can be used. For example, the following [Formula 11],
[Chemical formula 12] is exemplified. The present invention is not limited to the following compounds.

[0053]

Embedded image F (CF ₂ CF ₂ CF ₂ O) _m CF ₂ CF ₂ COOH

[0054]

Embedded image CF ₃ [OCF (CF ₃ ) CF ₂ ] _j (OC
F ₂ ) _k COOH

In the above chemical formula, m, j and k each represent an integer of 1 or more. The molecular weight of the perfluoropolyether having a carboxyl group at the terminal is not particularly limited, but is practically preferably about 600 to 5000, and more preferably 1000 to 4000. If the molecular weight is too large, the effect of the terminal group as an adsorptive group is diminished, and at the same time, the perfluoropolyether chain becomes large, so that it becomes difficult to dissolve in existing hydrocarbon solvents. Conversely, if the molecular weight is too small, the lubricating effect of the perfluoropolyether chain will be lost.

In the perfluoropolyether having a carboxyl group at the terminal, the perfluoropolyether chain may be partially hydrogenated. That is, a part (50% or less) of the fluorine atoms of the perfluoropolyether chain may be replaced with a hydrogen atom. In this case, a partially hydrogenated perfluoropolyether may be used as the perfluoropolyether.

As the amine, primary amine, secondary amine
Both amines and tertiary amines can be used, and quaternary ammonium compounds can also be used. The structure of the amine to be used is also arbitrary, such as a branched structure, an isomer structure,
It can be arbitrarily selected irrespective of the alicyclic structure, molecular weight, and presence or absence of an unsaturated bond. However, the amine preferably has an alkyl group in the molecule, and particularly when the amine has an alkyl group having 10 or more carbon atoms, a high effect is obtained.

The compound represented by Chemical Formula 9 applied to the lubricant layer 5 constituting the magnetic recording medium 10 of the present invention is defined as a third compound. The third compound is a compound of a perfluoropolyether having a terminal carboxyl group and a diamine. The third compound can be synthesized, for example, by mixing a monofunctional perfluoropolyether and a diamine and heating the mixture at a temperature equal to or higher than the melting point of the used diamine.

Here, as the monofunctional perfluoropolyether having a carboxyl group at the terminal used for synthesizing the third compound shown in the above [Chemical formula 9], a commercially available monofunctional perfluoropolyether can be used. For example, the following [Formula 13],
Examples shown in [Formula 14] are given. The present invention is not limited to the following compounds.

[0060]

Embedded image F (CF ₂ CF ₂ CF ₂ O) _m CF ₂ CF ₂ COOH

[0061]

Embedded image CF ₃ [OCF (CF ₃ ) CF ₂ ] _j (OC
F ₂ ) _k COOH

In the above chemical formula, m, j and k each represent an integer of 1 or more. The molecular weight of the perfluoropolyether having a carboxyl group at the terminal is not particularly limited, but is practically preferably about 600 to 5000, and more preferably 1000 to 4000. If the molecular weight is too large, the effect of the terminal group as an adsorptive group is diminished, and at the same time, the perfluoropolyether chain becomes large, so that it becomes difficult to dissolve in existing hydrocarbon solvents. Conversely, if the molecular weight is too small, the lubricating effect of the perfluoropolyether chain will be lost.

In the perfluoropolyether having a carboxyl group at the terminal, the perfluoropolyether chain may be partially hydrogenated. That is, a part (50% or less) of the fluorine atoms of the perfluoropolyether chain may be replaced with a hydrogen atom. In this case, a partially hydrogenated perfluoropolyether may be used as the perfluoropolyether.

The amine may be of any structure and the like, and may be arbitrarily selected irrespective of the branched structure, isomer structure, alicyclic structure, molecular weight, and presence or absence of an unsaturated bond.

The method of applying the lubricant containing the first to third compounds shown in the above [Chemical Formula 7], [Chemical Formula 8] and [Chemical Formula 9] on the aromatic alcohol treatment layer 4 is as follows. The top coat method is mentioned.

The coating amount is 0.05 [mg / m ² ] to 10
It is preferably 0 [mg / m ² ], more preferably 0.1 [mg / m ² ] to 50 [mg / m ² ]. If the applied amount of the lubricant is too small, the effect of lowering the friction coefficient, abrasion resistance, and the improvement of the durability cannot be obtained. If the applied amount is too large, the distance between the sliding member and the magnetic layer 2 is reduced. The sticking phenomenon occurs, and the running property deteriorates.

Further, a back coat layer 6 may be formed on the main surface of the non-magnetic support 1 opposite to the side on which the magnetic layer 2 is formed, and the back coat layer 6 comprises an inorganic powder component and a binder. It is formed by applying a back coat paint obtained by mixing and dispersing a resin with an organic solvent on the non-magnetic support 1.

The back coat layer 6 preferably contains carbon black. As the inorganic powder, calcium carbonate and an inorganic powder having a Mohs hardness of 5 to 9 are preferable. When forming the back coat layer 6, it is preferable to use two types of carbon black having different average particle sizes. In this case, it is preferable to use fine carbon black having an average particle size of 10 to 20 [nm] and coarse carbon black having an average particle size of 230 to 300 [nm].

In general, the surface electric resistance of the back coat layer 6 can be set low and the light transmittance can be set low by adding the above-mentioned fine particle carbon black.

In a device for recording or reproducing data on or from a magnetic recording medium, there are generally many devices that use the light transmittance of a magnetic tape and are used for operation signals. The addition of carbon black is effective for reducing the light transmittance. In addition, the particulate carbon black generally has excellent lubricant retention, and contributes to a reduction in friction coefficient when used in combination with a lubricant.

On the other hand, when the particle size is 230 to 300 [n
m) has a function as a solid lubricant, and forms minute projections on the surface of the back layer, thereby reducing the contact area and contributing to a reduction in the friction coefficient. However, the coarse-grained carbon black has a drawback that in a severe running system, the tape slips easily from the back coat layer 6 and the error ratio increases.

Specific products of the particulate carbon black that can be used in the present invention include the following. For example, RAVEN2000B (1
8 [nm]), RAVEN 1500B (17 [nm])
(Above, manufactured by Columbia Carbon Co., Ltd.), BP800 (17
[Nm]) (manufactured by Cabot Corporation), PRINTENT90
(14 [nm]), PRINTEX95 (15 [n
m]), PRINTEX85 (16 [nm]), PRI
NTEX75 (17 [nm]) (all manufactured by Degussa),
# 3950 (16 [nm]) (Mitsubishi Chemical Industries, Ltd.)
Made).

As a specific product of coarse carbon black, thermal black (270 [nm])
(Manufactured by Khan Karb), RAVEN MTP (275
[Nm]) (manufactured by Columbia Carbon Co., Ltd.).

In the case of using two kinds of back coat layers 6 having different average particle sizes,
[Nm] fine particle carbon black, 230 to 30
The content ratio (weight ratio) of the coarse carbon black of 0 [nm] is preferably in the range of fine carbon black: coarse carbon black = 98: 2 to 75:25,
More preferably, it is 95: 5 to 85:15.

The content of carbon black (in the case of adding fine particles and coarse particles, the total amount thereof) in the back coat layer 6 is usually 30 to 80 [per 100 parts by weight of a binder described later. Parts by weight], and preferably 45 to 65 [parts by weight].

The inorganic powder having a Mohs hardness of 5 to 9 is used for the purpose of imparting repeated running durability to the tape and strengthening the back coat layer 6. When these inorganic powders are used together with carbon black or calcium carbonate, the backcoat layer is less deteriorated even by repeated sliding due to its filler effect, and a strong backcoat layer 6 can be produced.

When the inorganic powder used for forming the back coat layer 6 has a relatively high Mohs hardness of 5 to 9, an appropriate polishing force is generated, and adhesion to a tape guide pole or the like is reduced. . In particular, when used in combination with calcium carbonate, the sliding characteristics with respect to a guide pole having a rough surface are improved, and the friction coefficient of the back coat layer 6 can be stabilized.

The inorganic powder having a Mohs hardness of 5 to 9 used for forming the back coat layer 6 constituting the magnetic recording medium 10 of the present invention preferably has an average particle size of 80 to 250 [nm], more preferably. Is 100-210
[Nm].

Examples of the inorganic powder having a Mohs hardness of 5 to 9 used for forming the back coat layer 6 include α-iron oxide, α-alumina, and chromium oxide (Cr ₂ O ₃ ). These powders may be used alone or in combination. Of these, α-iron oxide and α-alumina are preferred.

The content of the inorganic powder having a Mohs hardness of 5 to 9 is usually 3 parts by weight per 100 parts by weight of carbon black.
To 30 [parts by weight], preferably 3 to 20 [parts by weight]. In particular, the back coat layer 6 of the present invention preferably contains the two types of carbon black having different average particle sizes, the calcium carbonate having the above particle size, and the inorganic powder having the specific Mohs hardness.

Examples of the binder resin used for forming the back coat layer 6 include a thermoplastic resin, a thermosetting resin, a reactive resin, and a mixture thereof. Examples of the thermoplastic resin include vinyl chloride, vinyl acetate, vinyl alcohol, maleic acid, acrylic acid, acrylic acid ester, vinylidene chloride, acrylonitrile, methacrylic acid, methacrylic acid ester, styrene, butadiene,
Examples include a polymer or a copolymer containing ethylene, vinyl butyral, vinyl acetal, and vinyl ether as constituent units.

As the copolymer, for example, vinyl chloride-
Vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylate-acrylonitrile copolymer, acrylate-vinylidene chloride copolymer, acrylate-styrene copolymer Copolymer, methacrylate-acrylonitrile copolymer, methacrylate-vinylidene chloride copolymer, methacrylate-styrene copolymer, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, styrene -Butadiene copolymer and chlorovinyl ether-acrylate copolymer.

In addition to the above, polyamide resins, cellulose resins (cellulose acetate butyrate, cellulose diacetate, cellulose propionate, nitrocellulose, etc.), polyvinyl fluoride, polyester resins, polyurethane resins, various rubber resins, etc. Can be applied.

The thermosetting resin or the reactive resin includes, for example, phenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, acrylic reaction resin, formaldehyde resin, silicone resin, epoxy resin. Examples thereof include a polyamide resin, a mixture of a polyester resin and a polyisocyanate prepolymer, a mixture of a polyester polyol and a polyisocyanate, and a mixture of a polyurethane and a polyisocyanate.

Examples of the organic solvent used for the coating for the back coat layer 6 include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and glycol acetate monoester. Noester solvents such as ethyl ether; glycol ether solvents such as glycol dimethyl ether, glycol monoethyl ether and dioxane; aromatic hydrocarbon solvents such as benzene, toluene and xylene; aliphatic hydrocarbon solvents such as hexane and heptane; methylene Chlorinated hydrocarbon solvents such as chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, and dichlorobenzene, and general-purpose solvents can be used.

The back coat layer 6 may use a lubricant in combination. In this case, there is a method of internally adding a lubricant to the back coat layer 6, or a method of applying a lubricant on the back coat layer 6. As the lubricant, conventionally known lubricants such as fatty acids, fatty acid esters, fatty acid amides, and aliphatic alcohols can be used.

Next, the magnetic recording medium 10 of the present invention will be described with reference to specific examples and comparative examples.

First, as the compound applied to the formation of the lubricant layer 5 of the magnetic recording medium 10 of the present invention, the first compound shown in the above [Chemical Formula 7] is synthesized. As a bifunctional perfluoropolyether having a carboxyl group at a terminal serving as a raw material, a compound represented by the following [Chemical Formula 15] having a molecular weight of 4000 is applied.

HOOCCF ₂ (OC ₂ F ₄ ) _p (OC
F ₂ ) _q OCF ₂ COOH (where p and q each represent an integer of 1 or more)

A 20 g of bifunctional perfluoropolyether having a carboxyl group at the terminal of [Chemical Formula 15] was placed in a round bottom flask, and 3.6 g of octadecylamine was added. Next, the mixture was heated and dissolved at 50 ° C., sufficiently stirred to be uniform, and then cooled to produce [Compound 1] shown in the following [Table 1].

Next, in the same manner as in [Compound 1], compounds [Compound 2] to [Compound 5] of a bifunctional perfluoropolyether having a terminal carboxyl group and an amine shown in [Table 1] below Was synthesized. In Table 1, p, q, and n each represent an integer of 1 or more.

[0091]

[Table 1]

Next, a sample magnetic tape is manufactured.
Co is applied to a 5.0 [μm] thick polyethylene terephthalate film by an oblique evaporation method, and a film thickness of 80 [n] is formed.
m] was formed. Then, a DC voltage of -1.5 [kV] was applied to the metal magnetic thin film using a high frequency plasma of a mixed gas of ethylene and argon with the raw material of the electrode and the magnetic recording medium 10 as a counter electrode, A discharge is performed and about 15 [n]
m] of the carbon protective layer 3 was formed.

Next, on the surface of the polyethylene terephthalate film opposite to the surface on which the metal magnetic thin film is formed, a thickness of 0.1 mm made of carbon black and polyurethane resin is used.
A back coat layer 6 of 5 [μm] was formed.

Next, on the carbon protective layer 3, a predetermined aromatic alcohol shown in Table 2 below was dissolved in isopropyl alcohol, and the amount of the aromatic alcohol applied was 2 mg / m ^2. ], 5 [mg / m ² ], 10 [m
g / m ² ] to form an aromatic alcohol-treated layer 4.

Next, as shown in the following [Table 2], a lubricant solution prepared by dissolving any of compounds 1 to 5 in [Table 1] in toluene was applied to the surface of the aromatic alcohol treatment layer 4. The coating amount was 5 [mg / m ² ].
The magnetic recording medium 10 obtained in this manner was used in 6.35.
The sample was cut into [mm] widths, and magnetic tapes of samples as [Example 1] to [Example 15] were produced.

[0096]

[Table 2]

Next, as a comparative example, compounds 1 to 5 in Table 1 shown in Table 2 were formed without forming an aromatic treatment layer 4 with an aromatic alcohol on the carbon protective layer 3. Was dissolved in toluene, and the resulting lubricant solution was applied so that the coating amount was 5 [mg / m ² ]. The magnetic recording medium 10 obtained in this way is referred to as 6.
Cut to 35 [mm] width, [Comparative Example 1] ~
A magnetic tape of a sample to be [Comparative Example 5] was produced.

(Evaluation of Durability and Runnability) The magnetic tapes of the respective samples of [Example 1] to [Example 15] and [Comparative Example 1] to [Comparative Example 5] produced as described above were used. Temperature 40 ° C, humidity 30%, and temperature -5
Under the respective conditions of ° C., the lubricant was used to determine the coefficient of friction, shuttle durability, the amount of powder falling off the magnetic head after the shuttle durability measurement, and the amount of abrasion by the methods shown in the following (1) to (4). Immediately after application, temperature 45 ° C, humidity 8
Each measurement was performed after storage for 30 days in a 0% environment. The measurement results are shown in Table 3 below (just after the lubricant was applied).
And Table 4 (after storage for 30 days in an environment of 80% humidity).

The shuttle durability was measured using a commercially available digital video camcorder (VX-100 manufactured by Sony).
0), a commercially available digital video camcorder (VX-1000 manufactured by Sony)
Was modified to make the MR head usable.

(1) Method of Measuring Friction Coefficient The coefficient of friction was measured by running a sample magnetic tape for 100 passes on a stainless steel guide pin in a thermostat. In addition, the numerical value of the 100th pass of friction running was defined as the friction coefficient. (2) Shuttle durability measurement method Shuttle durability is controlled by controlling the temperature to -5 ° C in a thermostat.
The reproduction was repeated for 2 minutes each time, and the number of shuttles until the reproduction output decreased by 3 dB from the initial output was measured. (3) Amount of Deposits on MR Head The amount of deposits on the MR head was observed by an optical microscope after repeating reproduction for 30 minutes 50 times with an optical microscope. 50% or less adhesion to the area but no effect on output), Δ (level of 50% or less adhesion to the head area and affecting the output), × (50 of the head area)
% Or more, or clogs occur during running). (4) MR Head Wear Measurement Method The MR head wear was measured by measuring the nm of the height of the MR head after the reproduction for 30 minutes was repeated 50 times from the initial height.

[0101]

[Table 3]

[0102]

[Table 4]

As shown in the above [Table 3] and [Table 4], an aromatic alcohol-treated layer 4 was formed on the carbon protective layer 3, and a bifunctional perfluoropolyether having a terminal carboxyl group was formed thereon. In the magnetic tapes of Examples 1 to 15 having a structure in which the lubricant layer 5 coated with a compound of amine and amine was formed, even under various use conditions such as high temperature and high humidity, high temperature and low humidity, and low temperature. Very good results were obtained with very little deterioration in friction coefficient, still durability, shuttle durability, and head wear characteristics, and no increase in the amount of head deposits. Further, even after long-term storage, the deterioration of the coefficient of friction, still durability, shuttle durability, and head wear characteristics was extremely small, and good results were obtained.

Further, as shown in Table 2, the coating amount of the aromatic alcohol was set to be equal to or larger than the coating amount of the compound of perfluoropolyether and amine in the lubricant [Example 2]
And [Example 3], [Example 5] and [Example 6], [Example 8] and [Example 9], [Example 1]
1] and [Example 12], [Example 14], and [Example 15], the coating amount of the same type of aromatic alcohol is less than the coating amount of the compound of perfluoropolyether and amine in the lubricant. [Example 1], [Example 4],
[Example 7], compared with [Example 10] and [Example 13], the friction coefficient after long-term storage shown in [Table 4],
The evaluation results of the powder drop condition and various characteristics of the MR head wear amount were good, and it was found that the initial characteristics were maintained.

On the other hand, in the magnetic tapes of the samples of Comparative Examples 1 to 5 which were produced without forming the aromatic treatment layer 4 with the aromatic alcohol on the carbon protective layer 3, As shown in [4], the coefficient of friction increased greatly after storage, the measurement results of the shuttle durability and the powder dropping condition deteriorated, and the wear amount of the MD head increased.

Next, as the compound to be applied to the formation of the lubricant layer 5 of the magnetic recording medium 10 of the present invention, the second compound shown in the above [Chemical Formula 8] is synthesized. As a perfluoropolyether having a carboxyl group at the end serving as a raw material,
A compound having a molecular weight of 1700 and represented by the following [Formula 16] is applied.

Embedded image F (CF ₂ CF ₂ CF ₂ O) _m CF ₂ CF ₂ COOH (where m represents an integer of 1 or more)

A 20 g of perfluoropolyether having a carboxyl group at the terminal of [Chemical Formula 16] was placed in a round bottom flask, and 3.2 g of octadecylamine was added. Next, the mixture was heated and dissolved at 50 ° C., sufficiently stirred to be uniform, and then cooled to obtain [Compound 6] shown in the following [Table 5].

Next, compounds [compound 7] to [compound 10] of perfluoropolyether having a terminal carboxyl group and an amine shown in the following [Table 5] were synthesized in the same manner as [compound 6]. did. In Table 5, j,
k and m each represent an integer of 1 or more.

[0109]

[Table 5]

Next, a sample magnetic tape is manufactured.
Co is applied to a 5.0 [μm] thick polyethylene terephthalate film by an oblique evaporation method, and a film thickness of 80 [n] is formed.
m] was formed. Then, a DC voltage of -1.5 [kV] was applied to the metal magnetic thin film using a high frequency plasma of a mixed gas of ethylene and argon with the raw material of the electrode and the magnetic recording medium 10 as a counter electrode, A discharge is performed and about 15 [n]
m] of the carbon protective layer 3 was formed.

Next, on the surface of the polyethylene terephthalate film opposite to the surface on which the metal magnetic thin film is formed, a thickness of carbon black and polyurethane resin of 0.1 mm is applied.
A back coat layer 6 of 5 [μm] was formed.

Next, on the carbon protective layer 3, a predetermined aromatic alcohol shown in the following Table 6 was dissolved in isopropyl alcohol, and the amount of the aromatic alcohol applied was 2 mg / m ^2. ], 5 [mg / m ² ], 10 [m
g / m ² ] to form an aromatic alcohol-treated layer 4.

Next, a lubricant solution prepared by dissolving any of compounds 6 to 10 in [Table 5] in toluene shown in [Table 6] below was applied to the surface of the aromatic alcohol treatment layer 4. The coating amount was 5 [mg / m ² ]. The magnetic recording medium 10 obtained in this way is referred to as 6.
Cut to a width of 35 [mm], and each of [Example 16] to
Example 30 A sample magnetic tape to be used was prepared.

[0114]

[Table 6]

Next, as a comparative example, compounds 6 to 10 in [Table 5] shown in [Table 6] were formed without forming an aromatic treatment layer 4 with an aromatic alcohol on the carbon protective layer 3. Was dissolved in toluene, and the resulting lubricant solution was applied so that the coating amount was 5 [mg / m ² ]. The magnetic recording medium 10 thus obtained is
Cut to 6.35 [mm] width, each [Comparative Example 6]
To [Comparative Example 10] were prepared.

(Evaluation of Durability and Runnability) The magnetic tapes of the respective samples of [Example 16] to [Example 30] and [Comparative Example 6] to [Comparative Example 10] produced as described above were used. Under the conditions of a temperature of 40 ° C., a humidity of 30%, and a temperature of −5 ° C., the magnetic head after measuring the friction coefficient, shuttle durability, and shuttle durability by the methods shown in the following (1) to (4). About the amount of powder falling off and the amount of wear, immediately after the lubricant was applied, and at a temperature of 45 ° C,
Each measurement was performed after storage for 30 days in an environment with a humidity of 80%. The measurement results are shown in the following [Table 7] (immediately after applying the lubricant) and [Table 8] (after storage for 30 days in an environment of 80% humidity).

For measuring the shuttle durability, a commercially available digital video camcorder (VX-100 manufactured by Sony) was used.
0), a commercially available digital video camcorder (VX-1000 manufactured by Sony)
Was modified to make the MR head usable.

(1) Method of Measuring Friction Coefficient The friction coefficient was measured by running a magnetic tape of a sample on a stainless steel guide pin for 100 passes in a thermostat. In addition, the numerical value of the 100th pass of friction running was defined as the friction coefficient. (2) Shuttle durability measurement method Shuttle durability is controlled by controlling the temperature to -5 ° C in a thermostat.
The reproduction was repeated for 2 minutes each time, and the number of shuttles until the reproduction output decreased by 3 dB from the initial output was measured. (3) Amount of Deposits on MR Head The amount of deposits on the MR head was observed by an optical microscope after repeating reproduction for 30 minutes 50 times with an optical microscope. 50% or less adhesion to the area but no effect on output), Δ (level of 50% or less adhesion to the head area and affecting the output), × (50 of the head area)
% Or more, or clogs occur during running). (4) MR Head Wear Measurement Method The MR head wear was measured by measuring the nm of the height of the MR head after the reproduction for 30 minutes was repeated 50 times from the initial height.

[0119]

[Table 7]

[0120]

[Table 8]

As shown in the above [Table 7] and [Table 8], an aromatic alcohol-treated layer 4 was formed on the carbon protective layer 3, and a perfluoropolyether having a carboxyl group at the terminal and an amine were formed thereon. In the magnetic tapes of Examples 16 to 30 having the structure in which the lubricant layer 5 coated with the compound of Example 1 was formed, even under various use conditions such as high temperature and high humidity, high temperature and low humidity, and low temperature, Very good results were obtained with very little deterioration in coefficient, still durability, shuttle durability, and head wear characteristics, and no increase in head deposits. Also, even after long-term storage,
The deterioration of the coefficient of friction, still durability, shuttle durability, and head wear characteristics was extremely small, and good results were obtained.

Further, in particular, as shown in Table 6, the coating amount of the aromatic alcohol was set to be equal to or more than the coating amount of the compound of perfluoropolyether and amine in the lubricant [Example 1].
7] and [Example 18], [Example 20] and [Example 21], [Example 23] and [Example 24],
[Example 26], [Example 27], [Example 29]
And [Example 30], the coating amount of the same type of aromatic alcohol is less than the coating amount of the compound of perfluoropolyether and amine in the lubricant [Example 16],
[Example 19], [Example 22], [Example 25],
Compared with [Example 28], the evaluation results of various characteristics such as the coefficient of friction, the state of powder falling off, and the wear amount of the MR head after the long-term storage shown in [Table 8] are good, and the initial results after the long-term storage are good. It was found that the properties were maintained.

On the other hand, in the magnetic tapes of the samples of Comparative Examples 6 to 10 which were produced without forming the aromatic treatment layer 4 with the aromatic alcohol on the carbon protective layer 3, As shown in 8], after storage, the increase in the coefficient of friction was large, the measurement results of the shuttle durability and the powder dropping condition were deteriorated, and the wear amount of the MD head was increased.

Next, as the compound applied to the formation of the lubricant layer 5 of the magnetic recording medium 10 of the present invention, the third compound shown in the above [Chemical Formula 9] is synthesized. As a perfluoropolyether having a carboxyl group at the end serving as a raw material,
A compound having a molecular weight of 1700 and represented by the following [Formula 17] is applied.

Embedded image F (CF ₂ CF ₂ CF ₂ O) _m CF ₂ CF ₂ COOH (where m represents an integer of 1 or more)

A 20 g of perfluoropolyether having a carboxyl group at the terminal of [Chemical Formula 17] was placed in a round bottom flask, and 0.52 g of 1,4-diaminobutane was added. Next, the mixture was dissolved by heating at 50 ° C., sufficiently stirred to be uniform, and then cooled and [compound 11] shown in the following [Table 9].
Was prepared.

Next, in the same manner as in [Compound 11], compounds [Compound 12] to [Compound 15] of perfluoropolyether having a carboxyl group at a terminal and a diamine shown in [Table 9] below were prepared. Synthesized. In Table 9, j, k, and m each represent an integer of 1 or more.

[0127]

[Table 9]

Next, a sample magnetic tape is manufactured.
Co is applied to a 5.0 [μm] thick polyethylene terephthalate film by an oblique evaporation method, and a film thickness of 80 [n] is formed.
m] was formed. Then, a DC voltage of -1.5 [kV] was applied to the metal magnetic thin film using a high frequency plasma of a mixed gas of ethylene and argon with the raw material of the electrode and the magnetic recording medium 10 as a counter electrode, A discharge is performed and about 15 [n]
m] of the carbon protective layer 3 was formed.

Next, on the surface of the polyethylene terephthalate film opposite to the surface on which the metal magnetic thin film is formed, a thickness of 0.1 mm made of carbon black and polyurethane resin is used.
A back coat layer 6 of 5 [μm] was formed.

Next, on the carbon protective layer 3, a predetermined aromatic alcohol shown in the following Table 10 was dissolved in isopropyl alcohol, and the amount of the aromatic alcohol applied was 2 mg / m ^2. ], 5 [mg / m ² ], 10
[Mg / m ² ] to form an aromatic alcohol-treated layer 4.

Next, a lubricant solution prepared by dissolving any of compounds 11 to 15 in [Table 9] shown in [Table 9] in toluene was added to the aromatic alcohol-treated layer 4 shown in [Table 9].
Was applied such that the coating amount was 5 [mg / m ² ]. The magnetic recording medium 10 thus obtained is
6. Cut to a width of 6.35 [mm].
1] to [Example 45] were prepared as sample magnetic tapes.

[0132]

[Table 10]

Next, as a comparative example, the compound 11 in [Table 9] shown in [Table 9] was obtained without forming the aromatic treatment layer 4 with an aromatic alcohol on the carbon protective layer 3.
A lubricant solution prepared by dissolving any of Compounds 15 to 15 in toluene was applied so that the coating amount was 5 [mg / m ² ]. The magnetic recording medium 10 thus obtained
Was cut to a width of 6.35 [mm], and magnetic tapes of samples as Comparative Examples 11 to 15 were produced.

(Evaluation of durability and running property) The magnetic tapes of the respective samples of [Example 31] to [Example 45] and [Comparative Example 11] to [Comparative Example 15] manufactured as described above were used. Under the conditions of a temperature of 40 ° C., a humidity of 30%, and a temperature of −5 ° C., the following (1) to (4)
The friction coefficient, shuttle durability, the amount of powder falling off the magnetic head after the shuttle durability measurement, and the amount of abrasion were measured immediately after the lubricant was applied and at the temperature of 45.
Each measurement was performed after storing for 30 days in an environment at a temperature of 80 ° C and a humidity of 80%. The measurement results are shown in the following [Table 11] (immediately after applying the lubricant) and [Table 12] (after storage for 30 days in an environment of 80% humidity).

For measuring the shuttle durability, a commercially available digital video camcorder (VX-100 manufactured by Sony) was used.
0), a commercially available digital video camcorder (VX-1000 manufactured by Sony)
Was modified to make the MR head usable.

(1) Method of Measuring Friction Coefficient The friction coefficient was measured by running a magnetic tape of a sample 100 times on a stainless steel guide pin in a thermostat. In addition, the numerical value of the 100th pass of friction running was defined as the friction coefficient. (2) Shuttle durability measurement method Shuttle durability is controlled by controlling the temperature to -5 ° C in a thermostat.
The reproduction was repeated for 2 minutes each time, and the number of shuttles until the reproduction output decreased by 3 dB from the initial output was measured. (3) Amount of Deposits on MR Head The amount of deposits on the MR head was observed by an optical microscope after repeating reproduction for 30 minutes 50 times with an optical microscope. 50% or less adhesion to the area but no effect on output), Δ (level of 50% or less adhesion to the head area and affecting the output), × (50 of the head area)
% Or more, or clogs occur during running). (4) MR Head Wear Measurement Method The MR head wear was measured by measuring the nm of the height of the MR head after the reproduction for 30 minutes was repeated 50 times from the initial height.

[0137]

[Table 11]

[0138]

[Table 12]

As shown in the above [Table 11] and [Table 12], the aromatic alcohol-treated layer 4 was formed on the carbon protective layer 3.
And a lubricant layer 5 on which a compound (compounds 11 to 15) of a perfluoropolyether having a carboxyl group at a terminal and a diamine was applied was formed thereon. In the magnetic tape of Example 45, even under various use conditions such as high temperature and high humidity, high temperature and low humidity, and low temperature, deterioration of the friction coefficient, still durability, shuttle durability, and head wear characteristics was extremely small, and the amount of head deposits was small. Very good results were obtained without any increase. In addition, even after long-term storage, friction coefficient and still durability,
The shuttle durability and the abrasion characteristics of the head were hardly deteriorated, and good results were obtained.

Further, as shown in Table 10, the coating amount of the aromatic alcohol was set to be equal to or larger than the coating amount of the compound of perfluoropolyether and amine in the lubricant [Example 3].
2] and [Example 33], [Example 35] and [Example 36], [Example 38] and [Example 39],
[Example 41], [Example 42], [Example 44]
And [Example 45], the coating amount of the same type of aromatic alcohol is less than the coating amount of the compound of perfluoropolyether and diamine in the lubricant [Example 31],
[Example 34], [Example 37], [Example 40],
Compared with [Example 43], the evaluation results of various characteristics such as the coefficient of friction, the state of dusting, and the wear amount of the MR head after the long-term storage shown in [Table 12] are good. It was found that the properties were maintained.

On the other hand, in the magnetic tapes of the samples of Comparative Examples 11 to 15 prepared without forming the aromatic treatment layer 4 with the aromatic alcohol on the carbon protective layer 3, As shown in [12], after the storage, the increase in the coefficient of friction was large, the measurement results of the shuttle durability and the powder falling condition were deteriorated, and the wear amount of the MD head was increased.

[0142]

According to the magnetic recording medium of the present invention, an excellent lubricating effect can be exhibited, and even under various conditions of use such as high temperature and high humidity, high temperature and low humidity, or low temperature, the friction coefficient and still durability can be improved. Very good performance results were obtained with very little deterioration in shuttle durability and head wear characteristics and no increase in head deposits.

Further, according to the magnetic recording medium of the present invention, various characteristics such as friction coefficient, still durability and shuttle durability can be maintained for a long period of time. And the deterioration of the output and the deterioration of the characteristics of the magnetic head can be reduced.

Further, since the amount of the aromatic alcohol applied is equal to or larger than the amount of the compound of the perfluoropolyether and the amine in the lubricant or the amount of the compound of the perfluoropolyether and the diamine, the friction even after long-term storage is maintained. The initial good condition could be maintained with respect to various characteristics such as a coefficient, a powder falling condition, and a wear amount of the MR head.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a magnetic recording medium of the present invention.

[Explanation of symbols]

Reference Signs List 1 nonmagnetic support, 2 magnetic layer, 3 carbon protective layer, 4 aromatic alcohol-treated layer, 5 lubricant layer, 6
Back coat layer, 10 magnetic recording medium

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10N 30:08 C10N 30:08 40:18 40:18 (72) Inventor Hiroshi Yatakai Kita Shinagawa, Shinagawa-ku, Tokyo 6-chome 7-35 Sony Corporation F-term (reference) 4H104 BB05A BD07A CD04A LA03 LA04 PA16 5D006 AA01 AA02 AA05 AA06 FA00

Claims (12)

[Claims] 1. A magnetic recording system comprising a magnetic layer made of a ferromagnetic metal thin film and a carbon protective film formed in this order on a nonmagnetic support, and used in a helical scan magnetic recording system using a magnetoresistive read head. A medium, having an aromatic alcohol-treated layer on the carbon protective layer, and a bifunctional perfluoropolyether having a terminal carboxyl group as shown in the following Chemical Formula 1 on the aromatic alcohol-treated layer. And a lubricant layer containing an amine compound. Embedded image (However, Rf represents a perfluoropolyether chain,
R ₁ , R ₂ , R ₃ and R ₄ represent hydrogen or a hydrocarbon group. ) 2. The aromatic alcohol layer is formed by applying an aromatic alcohol, and the lubricant layer comprises a bifunctional perfluoropolyether having a carboxyl group at a terminal represented by the following chemical formula 1. It is formed by applying a lubricant containing an amine compound, and the amount of the aromatic alcohol to be applied per unit area is a bifunctional perfluoropoly having a carboxyl group at a terminal contained in the lubricant. Of ether and amine compounds,
2. The magnetic recording medium according to claim 1, wherein the amount of application is equal to or more than the application amount per unit area. 3. The magnetic recording medium according to claim 1, wherein the aromatic alcohol is a phenol. 4. The magnetic recording medium according to claim 1, wherein said aromatic alcohol is a naphthol. 5. A magnetic recording used in a helical scan magnetic recording system using a magnetoresistive read head, in which a magnetic layer made of a ferromagnetic metal thin film and a carbon protective layer are sequentially formed on a nonmagnetic support. A medium, comprising: an aromatic alcohol-treated layer on the carbon protective layer; and a perfluoropolyether having a carboxyl group at a terminal, represented by the following chemical formula 2, and an amine on the aromatic alcohol-treated layer. A magnetic recording medium comprising a lubricant layer containing the compound of the formula (1). Embedded image (However, Rf represents a perfluoropolyether chain,
R ₁ , R ₂ , R ₃ and R ₄ represent hydrogen or a hydrocarbon group. ) 6. The aromatic alcohol layer is formed by applying an aromatic alcohol, and the lubricant layer is formed by a perfluoropolyether having a carboxyl group at a terminal represented by the above formula (2) and an amine. Formed by applying a lubricant containing the compound of the above, the application amount per unit area of the aromatic alcohol, perfluoropolyether having a terminal carboxyl group contained in the lubricant and amine 6. The magnetic recording medium according to claim 5, wherein the amount of the compound is equal to or more than the amount of the compound applied per unit area. 7. The magnetic recording medium according to claim 5, wherein the aromatic alcohol is a phenol. 8. The magnetic recording medium according to claim 5, wherein the aromatic alcohol is a naphthol. 9. A magnetic recording used in a helical scan magnetic recording system using a magnetoresistive read head, in which a magnetic layer made of a ferromagnetic metal thin film and a carbon protective layer are sequentially formed on a nonmagnetic support. A medium, comprising: an aromatic alcohol-treated layer on the carbon protective layer; and a perfluoropolyether having a carboxyl group at a terminal and a diamine represented by the following chemical formula 3 on the aromatic alcohol-treated layer. A magnetic recording medium comprising a lubricant layer containing the compound of the formula (1). Embedded image (Where Rf represents a perfluoropolyether chain; R represents a hydrocarbon group; R ₁ , R ₂ , R ₃ , R ₄ , R
₅ , R ₆ represents hydrogen or a hydrocarbon group. ) 10. The aromatic alcohol layer is formed by applying an aromatic alcohol, and the lubricant layer is formed of a perfluoropolyether having a carboxyl group at a terminal and a diamine represented by the above formula (3). Formed by applying a lubricant containing a compound, the amount of the aromatic alcohol applied per unit area, the perfluoropolyether having a terminal carboxyl group contained in the lubricant and diamine 10. The magnetic recording medium according to claim 9, wherein the amount of the compound applied is equal to or more than the amount applied per unit area. 11. The magnetic recording medium according to claim 9, wherein said aromatic alcohol is a phenol. 12. The magnetic recording medium according to claim 9, wherein the aromatic alcohol is a naphthol.