JPH10269547A - Magnetic disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording disk for high-density recording having high traveling durability. SOLUTION: This magnetic disk device for a magnetic recording system is formed with a magnetic film consisting of a metallic thin film and executes recording and reproducing at a number of revolutions of >=1000 rpm. In such a case, the magnetic film or the protective film formed on the magnetic film has a lubricating agent having at least a fluoroalkyl chain and alkyl chain within the molecule or a lubricating agent having at least two fluoroalkyl chains within the molecule or a lubricating gent contg, further alkylamine in these lubricating agents.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a floppy disk used as an external storage device of information equipment such as a computer.

[0002]

2. Description of the Related Art Due to the remarkable development of computer technology in recent years, magnetic disks such as floppy disks and hard disks used as storage devices have been increased in storage capacity.
High recording density is required. The density of hard disks has been increasing at a very high rate of expansion due to technological improvements in magnetic disks, heads, signal processing, and the like, and it is expected that the density will continue to increase in the future. On the other hand, a floppy disk has recently been provided with a high-density product that combines a high-performance disk and a head and a slider similar to a hard disk and rotates the disk at a high speed of about 3000 rpm. However, floppy disks have some technical difficulties that hard disks do not have, and therefore have several problems with high density. One of the reasons for this is that the magnetic film of a commercially available floppy disk is a so-called coating type medium made by applying a coating solution in which magnetic powder is dispersed in a binder onto a support, and is formed by sputtering like a hard disk. As compared with a magnetic film made of a thin metal film, the magnetic energy is lower, so that the electromagnetic conversion characteristics are inferior.

[0003] Further, since the support is flexible, the disk runout (vibration in the direction perpendicular to the disk surface) when the disk is rotated is much larger than that of the hard disk. For this reason, even in a floppy disk for high-density recording, like a hard disk, a protective film,
A lubricating film and a recording / reproducing method have been studied.

For example, Japanese Patent Application Laid-Open No. Sho 62-175925 describes a magnetic recording medium in which an oxide layer or a nitride layer is formed on the surface of a magnetic layer provided with a magnetic layer having perpendicular anisotropy and a protective layer. JP-A-62-175926 describes a perpendicular magnetic recording medium provided with a magnetic layer and a protective layer, in which the surface of the magnetic layer is subjected to plasma treatment. Also, in Japanese Patent Application Laid-Open No. 62-298923,
A method of providing a protective film of carbon or the like on a magnetic film is disclosed. Japanese Patent Application Laid-Open No. Sho 62-298917 discloses a method of providing an oxide protective film on a magnetic film.
Certainly, by providing a protective film on the magnetic film, the abrasion resistance of the disk surface is remarkably improved, and the durability is improved.However, the frictional force against the liner and the slider or the head during rotation is high, and the There has been a problem that the protective film gradually wears and eventually the magnetic film is scraped.

Therefore, a method has been proposed in which a lubricant is applied on the protective film to reduce the frictional force. JP-A-64-7
Japanese Patent Application Laid-Open No. 9934/993 discloses a method of supplying lubricant from a drive, and Japanese Patent Application Laid-Open No. 64-79936 discloses a method of supplying a liner by impregnating a lubricant.
Japanese Patent Application Laid-Open Publication No. Hei 11 (1995) discloses a method of applying a lubricant to a disk surface. Lubricants used in the prior art include perfluoropolyethers, perfluoroalkyl compounds containing polar groups, phosphate esters, thiols, and the like. By these techniques, the frictional force in the conventional low-speed running at about 300 rpm was significantly reduced, and the running durability was also significantly improved. However, in the above prior art, it was found that when the medium was run at a high speed of 3000 rpm or more, which is required for a medium for high-density recording, the frictional force increased in a short time, and the running durability was insufficient.

On the other hand, Japanese Patent Application Laid-Open No. 1-224926 discloses a method for improving the durability by reducing the static curl of the disk and reducing the deviation of the disk surface. In this way, run-out is reduced and durability is improved. However, even if this method is used, it is extremely difficult to eliminate the contact between the disk and the slider at a high speed rotation of 3000 rpm or more, so that the disk is worn, and sufficient running durability cannot be obtained. I understood. In the prior art described above, the running durability at low speed rotation was greatly improved by forming the protective film and the lubricating film and reducing the curl. However, in a floppy disk device for high-density recording, the number of revolutions is 10 times or more as compared with the conventional one, and it is very difficult to secure running durability by the conventional technology. In order to improve the recording density, the thickness of the protective film is also reduced from the conventional 20 to 30 nm to 10 nm.
It has to be reduced before and after, and furthermore, the surface roughness has to be greatly reduced as compared with the conventional one, and it has to be smoothed to _Rmax = 30 nm or less. For this reason, it becomes more difficult to secure running durability, and it is necessary to secure new technology.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a floppy disk having a ferromagnetic metal thin film having improved running durability, a recording density similar to that of a hard disk, and excellent reliability. It is assumed that.

[0008]

SUMMARY OF THE INVENTION The present invention is directed to a magnetic recording system in which recording / reproducing is performed at a rotation speed of 1000 rpm or more where a magnetic film made of a ferromagnetic metal thin film is formed on at least one surface of a flexible support. Is a magnetic disk having a lubricant comprising a carboxylic acid having at least a fluoroalkyl chain and an alkyl chain in a molecule on the magnetic film or on a protective film formed on the magnetic film.
Further, in the above magnetic disk, wherein the lubricant contains an alkylamine. Further, in a magnetic disk for a magnetic recording system in which a magnetic film made of a ferromagnetic metal thin film is formed on at least one surface of a flexible support and recording / reproduction is performed at a rotation speed of 1000 rpm or more, the magnetic film or This is a magnetic disk having a lubricant composed of a carboxylic acid having at least two fluoroalkyl chains in a molecule on a protective film formed on the film. A magnetic disk in which the lubricant contains an alkylamine. Further, the present invention is a magnetic disk cartridge for a magnetic recording system in which recording and reproduction are performed at a rotation speed of 1000 rpm or more, wherein the magnetic disk is rotatably housed in a cartridge having a liner on an inner surface.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a magnetic disk having a magnetic layer comprising a ferromagnetic metal thin film provided on at least one surface of a flexible support, and a protective film provided on the surface of the magnetic layer or on the magnetic layer. A carboxylic acid having a fluoroalkyl chain and an alkyl chain in a molecule as a lubricant or a carboxylic acid having two or more fluoroalkyl groups in a molecule as a lubricant is intended to improve running durability. Further, by adding an alkylamine to these lubricants, the lubricity of the lubricant is intended to be maintained for a long period of time.

In the present invention, a carboxylic acid having a fluoroalkyl chain and an alkyl chain, or a carboxylic acid having two or more fluoroalkyl groups is applied to the surface of the disk which can come into direct contact with the slider. Even in sliding where the slider contacts at high speed, very good lubricity is exhibited in a wide range of environments, and running durability can be significantly improved. Further, by adding an alkylamine to these lubricants, it is possible to improve the lubricant after running under severer sliding conditions or after long-term storage. In addition, the lubricant of the present invention is much more durable than perfluoropolyether which is a very good lubricant for hard disks, because the sliding conditions between floppy disks and hard disks are quite different. Conceivable.

Further, in the case of a floppy disk, the sliding with the liner attached to the inner surface of the cartridge is also an important problem. However, when the lubricant of the present invention is used, the frictional force is low, Very little wear. In addition, unevenness of the lubricant after running, which is observed when perfluoropolyether is used alone, does not occur in the present invention, and it is considered that the lubricant is uniformly distributed on the disk surface even after running.

The carboxylic acid having a fluoroalkyl chain and an alkyl chain in the molecule or the carboxylic acid having two fluoroalkyl chains in the molecule which can be used in the present invention has a fluoroalkyl group, an alkyl group and a carboxyl group at the molecular terminal. It is a chemical structure, and has 4 to 12 carbon atoms as a fluoroalkyl group and 8 to 12 carbon atoms as an alkyl group.
Twelve. Further, a linking group such as an alkylene group, an ester group, an ether group, or an amide group for linking these substituents may be contained in the molecule. If this compound has a small number of carbon atoms, a good protective effect cannot be obtained, and if the number of carbon atoms is too large, the crystallinity increases, and the coating suitability decreases.
It is not preferable because the lubricating effect is deteriorated. The specific chemical structure of such a compound is

[0013]

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At least one of R ¹ and R ² is a perfluoroalkyl group, and the other is an alkyl group, R ′, R ″
Represents an alkylene group. In these compounds, a carboxylic acid having two fluoroalkyl groups in a molecule in which both R ¹ and R ² are fluoroalkyl groups has a lower humidity and lower temperature environment than a carboxylic acid having a fluoroalkyl group and an alkyl group. Is preferred because of its high durability.

As the alkylamine used by adding to the fluorine-based carboxylic acid of the present invention, a generally known primary alkylamine can be used, and specifically, CH ₃ (CH ₂ ) ₇ NH ₂ CH ₃ (CH ₂ ) ₁₁ NH ₂ CH ₃ (CH ₂ ) ₁₅ NH ₂ CH ₃ (CH ₂ ) ₁₇ NH ₂ CH ₃ (CH ₂ ) ₇ CH = CH (CH ₂ ) ₈ NH ₂ CF ₃ (CF _{2 ) 8 CH 2 CH 2 NH 2} CF 3 (CF 2) may be mentioned ₅ CH ₂ NH ₂ and the like. By adding an alkylamine to the carboxylic acid having a fluoroalkyl group, excellent lubricity can be obtained even during long-term storage.

As a method for applying the lubricant of the present invention to the disk surface, a solution obtained by dissolving at least one of an organic acid and an amine in an organic solvent such as methanol is subjected to a wire bar method, a gravure method, a spray method, a dip coating method. After coating on the disk surface by a method such as a spin coating method or a spin coating method, a method of drying can be used. At this time, the solvent is preferably an organic solvent containing no fluorine,
A fluorinated solvent such as an alternative fluorocarbon may be used. Further, from the standpoint of production cost and environmental protection, the fluorine-containing lubricant of the present invention is preferably dissolved in a common organic solvent. do it.

The mixing ratio between the perfluoroalkyl group-containing carboxylic acid and the amine is preferably about 1: 1 in terms of molar ratio, which is most excellent in lubricity and corrosion resistance. The total amount of the lubricant applied is preferably 1 to 20 mg / m ² , and 3 to 10 mg / m ^2.
/ M ² is more preferred. If the coating amount is less than this, lubricating properties cannot be exhibited, and running durability is insufficient. On the other hand, if it is larger than this, the static and dynamic friction coefficients for the liner and the slider increase, and the slider is attracted to the disk to cause a head crash, a disk clutch, or an increase in the torque for the liner.

Next, a preferred embodiment of the present invention will be described. As the flexible support used in the present invention, a film of polyethylene terephthalate, polyethylene naphthalate, polyamide, polyimide or the like can be used. Further, a film containing a filler inside the film and having irregularities formed on the film surface may be used. In order to reduce the disk runout due to the centrifugal force of the disk rotation and the air flow inside the cartridge, a somewhat flexible support is preferable, the one having a thickness of 3 to 100 μm is preferable, and the one having a thickness of 30 to 70 μm is more preferable. .

In the present invention, an undercoat film for imparting heat resistance to the support and controlling the surface properties may be prepared. It is preferable to use a heat-resistant resin for the undercoat film,
As this resin, a general heat-resistant resin such as polyimide, polyamide and silicone resin can be used. Among them, silicone resins are preferred because they are easy to produce and have excellent blocking resistance. Such a silicone resin can be prepared by applying and drying an undercoating solution on a support by a sol-gel method using an organosilane compound such as phenyltriethoxysilane or 3-glycidoxypropyltrimethoxysilane as a starting material. A filler may be mixed in the undercoat film to control the surface properties, and is preferably a monodispersed spherical silica filler, and the height of protrusions on the surface of the prepared undercoat film is preferably 30 nm or less.

When the adhesion between the undercoating film and the support is insufficient, the support is subjected to a surface treatment with an additive such as a silane coupling agent, oxygen plasma, argon plasma, ultraviolet irradiation, electron beam irradiation, flame irradiation, or the like. Preferably, the support is subjected to a surface treatment.

As the ferromagnetic metal thin film serving as the magnetic layer in the magnetic recording medium of the present invention, a conventionally known vacuum deposited film or sputtering film can be used. When the magnetic film is formed by a sputtering method, the composition includes a conventionally known metal or alloy mainly composed of cobalt, and specifically, Co is used.
-Cr, Co-Ni-Cr, Co-Cr-Ta, Co-
Cr-Pt, Co-Cr-Ta-Pt, Co-Cr-P
t-Si, Co-Cr-Pt-B and the like can be used. In order to obtain particularly excellent electromagnetic conversion characteristics, Co-Cr-Ta, C
o-Cr-Pt is preferred. The thickness of the magnetic layer is 10 to 30
It is preferably set to 0 nm.

In this case, it is preferable to provide a base film for improving the magnetostatic characteristics of the magnetic film, and the composition of the base film may be a conventionally known metal or alloy. Cr, V, Ti, Ta, W, Si
Etc. or alloys thereof can be used.
-Ti, Cr-W are preferred. The thickness of the underlayer is 5 nm to 500 nm, preferably 10 nm to 2 nm.
00 nm. When a magnetic film is formed by a sputtering method, it is preferable to form the film while heating the substrate from the viewpoint of the magnetostatic properties of the magnetic film. At that time, the temperature is about 50 ° C. to 200 ° C. , More preferably 8
0-150 ° C.

When the magnetic film is formed by a vacuum deposition method, the composition may be a conventionally known metal or alloy mainly composed of cobalt, and specifically, Co, CoNi, CoF
e, etc. are deposited in an oxygen atmosphere and a film containing oxygen can be used. In particular, in order to improve the electromagnetic conversion characteristics, 90% or more, more preferably 95% or more, of the metal atoms constituting the magnetic layer is Co-O or Co-, which is cobalt.
Co-Fe containing O is preferable. The thickness of the magnetic layer is preferably from 100 to 300 nm, more preferably from 120 to 200 nm. In addition, the ferromagnetic metal thin film has a multilayer structure to improve the electromagnetic conversion characteristics,
It may have a nonmagnetic underlayer or an intermediate layer.

In the magnetic recording medium of the present invention, it is preferable to provide a protective layer on the ferromagnetic metal thin film in order to improve running durability and corrosion resistance. Examples of the protective film include oxides such as silica, alumina, titania, zirconia, cobalt oxide, and nickel oxide; nitrides such as titanium nitride, silicon nitride, and boron nitride; carbides such as silicon carbide, chromium carbide, and boron carbide; and graphite. And a protective film made of carbon such as amorphous carbon.

The carbon protective film is a carbon film made of an amorphous, graphite, diamond structure or a mixture thereof formed by a plasma CVD method, a sputtering method or the like, and particularly preferably a hard amorphous film generally called diamond-like carbon. Carbon film. This hard carbon film has a Vickers hardness of 1000 kg / mm ²
Above, preferably a hard carbon film of 2000 kg / mm ² or more. The crystal structure is an amorphous structure and is non-conductive. When the structure of the diamond-like carbon particles in the present application is measured by Raman spectroscopy, it can be confirmed by detecting a peak at 1520 to 1560 ^-1 cm. When the structure of the carbon film deviates from the diamond-like structure, the peak detected by Raman spectroscopy deviates from the above range, and the hardness of the carbon film also decreases, making it difficult to achieve the object of the present invention. come. This hard carbon protective film is formed by plasma CVD using a carbon-containing compound such as an alkane such as methane, ethane, propane, or butane, an alkene such as ethylene or propylene, or an alkyne such as acetylene, or a hydrogen or hydrocarbon atmosphere. It can be formed by sputtering using carbon as a target below. When the thickness of the hard carbon protective film is large, electromagnetic conversion characteristics deteriorate and adhesion to the magnetic layer decreases,
When the film thickness is small, abrasion resistance is insufficient.
It is preferably 20 nm, particularly preferably 5 to 10 nm. Further, the surface of the hard carbon protective film may be surface-treated with an oxidizing or inert gas for the purpose of further improving the adhesiveness with the lubricant provided on the hard carbon protective film.

Known lubricants may be used in combination with the lubricant of the present invention. As the lubricant to be added, known hydrocarbon-based lubricants, fluorine-based lubricants, extreme pressure additives and the like can be used. Examples of the hydrocarbon-based lubricant include carboxylic acids such as stearic acid and oleic acid, esters such as butyl stearate, sulfonic acids such as octadecylsulfonic acid, and phosphoric esters such as monooctadecyl phosphate.
Examples thereof include alcohols such as stearyl alcohol and oleyl alcohol, carboxylic acid amides such as stearate amide, and amines such as stearylamine.

Examples of the fluorine-based lubricant include lubricants in which part or all of the alkyl groups of the hydrocarbon-based lubricant are substituted with a fluoroalkyl group or a perfluoropolyether group. Examples of the perfluoropolyether include a perfluoromethylene oxide polymer, a perfluoroethylene oxide polymer, a perfluoro-n-propylene oxide polymer (CF ₂ CF ₂ CF ₂ O) _n , and a perfluoroisopropylene oxide polymer ( CF (CF ₃ )
CF ₂ O) _n or a copolymer thereof. Further, a compound having a polar functional group such as a hydroxyl group, an ester group, or a carboxyl group at a terminal or in a molecule has a high effect of reducing a frictional force, and thus is preferable. The molecular weight is 500-
It is preferably 5000 to 3000. Below that, the volatility is high and the lubricity is low. If the viscosity is higher than this, the slider and the disk are likely to be attracted to each other, so that running stop, head crash and the like are likely to occur. Specific examples of the perfluoropolyether include those commercially available under the trade names such as FOMBLIN from Ausimont and KRYTOX from DuPont.

Examples of extreme pressure additives include phosphoric esters such as trilauryl phosphate, phosphites such as trilauryl phosphite, thiophosphites and thiophosphoric esters such as trilauryl trithiophosphite, and the like. And sulfur-based extreme pressure agents such as dibenzyl sulfide.

Examples of the rust preventives usable in the present invention include nitrogen-containing heterocycles such as benzotriazole, benzimidazole, purine and pyrimidine, and induced resistance, benzothiazole, 2-benzothiazole obtained by introducing an alkyl side chain or the like into the mother nucleus thereof. Mercaptobenzothiazole, tetrazaindene ring compound,
Nitrogen- and sulfur-containing heterocycles such as thiouracil compounds and derivatives thereof. The tetrazaindene ring compounds that can be used for such purposes include the following.

[0030]

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Here, R is a hydrocarbon group selected from an alkyl group, an alkoxy group and an alkylamide group.
Particularly preferably, it has 3 or more and 20 or less carbon atoms, and in the case of alkoxy, in ROCOCH ₂ —, R is C ₃ H ₇
-, C ₆ H ₁₃ -, in the case of phenyl or alkyl _{groups, C 6 H 13 -, C} 9 H 19 -, C 17 H 35 - and the like, wherein in the case of an alkylamide NHCOCH ₂ - of R Is phenyl or C ₃ H ₇ —. Further, examples of the thiouracil ring compound include the following.

[0032]

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Here, R is a hydrocarbon group having 3 or more carbon atoms. The amount of lubricant applied is 0.5 to 20 mg / m
² , preferably 0.1 to 5 mg / rust inhibitor.
m ² is preferred. Particularly preferred is a lubricant of 1 to 10 mg /
a rust inhibitor 0.5~2mg / m ² with respect to m ^2.

The apparatus using the floppy disk of the present invention has a rotation speed of 1,000 to 10,000 rpm, preferably 2,000 to 7,500 rpm. The head is preferably of a type in which a slider is attached to a suspension used for a hard disk, and can stably run by being sandwiched from above and below the disk. In addition to the conventional inductive head, an MR head can be used. In addition, although the disk runout varies depending on the device used, the smaller the size, the better the durability, and even if the present invention is used, the vehicle can run without any problem even if the runout is about 0.2 mm.

[0035]

The present invention will be described in more detail with reference to the following examples. Examples 1-4 On a polyethylene naphthalate film having a maximum projection roughness of 0.01 μm and a thickness of 63 μm, 3-glycidoxypropyltrimethoxysilane, phenyltriethoxysilane, hydrochloric acid, and aluminum acetylacetonate were dissolved in ethanol. After applying the solution by gravure coating method,
It is dried at 100 ° C. and subsequently baked at 170 ° C. for 10 seconds to be polymerized and cured, and has a thickness of 1 μm substantially free from protrusions.
Was prepared. This film was set in a sputtering apparatus, and the substrate was heated to 150 ° C., and the Cr—Ti base film was formed by DC magnetron sputtering.
Then, a Co-Cr-Pt magnetic film was formed to a thickness of 30 nm, and a hard carbon protective film was formed thereon by a plasma CVD method using methane as a raw material. Next, the lubricant shown in Table 1 was coated on this protective film with HCFC.
A solution dissolved in a mixed solvent of -225 and methanol was applied by a wire bar method so that the application amount of the fluorine-containing carboxylic acid was 5 mg / m ² to form a lubricating film.

Examples 5 to 8 On a polyethylene naphthalate film having a maximum projection roughness of 0.01 μm and a thickness of 63 μm, 3-glycidoxypropyltrimethoxysilane, phenyltriethoxysilane, hydrochloric acid and aluminum acetylacetonate were added with ethanol. After applying the solution dissolved in gravure coat method,
It is dried at 100 ° C. and subsequently baked at 170 ° C. for 10 seconds to be polymerized and cured, and has a thickness of 1 μm substantially free from protrusions.
Was prepared. This film was set in a sputtering apparatus, and the substrate was heated to 150 ° C., and the Cr—Ti base film was formed by DC magnetron sputtering.
Then, a Co—Cr—Pt magnetic film was formed to a thickness of 30 nm, and a hard carbon protective film was formed thereon by a plasma CVD method using methane as a raw material. Next, a mixed lubricant of a fluorine-containing carboxylic acid and an alkylamine shown in Table 1 was coated on the protective film with HCFC-225.
And a solution dissolved in a mixed solvent of methanol and methanol was applied by a wire bar method so that the total application amount of the lubricant was 6 mg / m ² to form a lubricating film. This base film, magnetic film, protective film,
Lubricating films were formed on both sides of the film. Then, this sample was punched into a 3.7-inch magnetic disk shape, and Z
A floppy disk was produced by assembling it into an IP (Fuji Photo Film) cartridge.

Comparative Examples 1 to 3 Example 1 was repeated except that the lubricant was changed to the lubricant shown in Table 1.
A sample was prepared in the same manner as described above. However, Fluorinert FC77 (manufactured by Sumitomo 3M) was used as a coating solvent in Comparative Example 1, and methyl ethyl ketone was used as a coating solvent in Comparative Example 2.

Comparative Examples 4 and 5 Example 5 except that the lubricant was changed to the lubricant shown in Table 1.
A sample was prepared in the same manner as described above. However, methyl ethyl ketone was used as a coating solvent in Comparative Example 4.

The prepared samples were evaluated for running durability by the following measuring method. [Measurement method] ZIP drive (Fuji Photo Film Co., Ltd.)
Then, while measuring the motor load current, the vehicle was continuously driven with the slider loaded on the innermost periphery. At this time, the disk runout in a state where the slider at the slider position was not loaded was 0.08 to 0.15 μm, and no clear relationship was found between the runout and the durability. When the motor load current greatly fluctuated, the motor was temporarily stopped, and the disk surface was visually observed. If any scratch was found, the test was stopped at that point and the test was performed for up to 100 hours.
The measurement was performed twice for one example and the comparative example, and the average value was obtained. Measurement environment is 23 ° C, 50% RH and 2
Performed at 3 ° C. and 10% RH. Also, observe the disk surface after running, observe scratches due to liner sliding and localization of lubricant (discolored concentric streaks). If there is no change from before running, excellent, slightly discolored Good, those with clear discoloration and scratches were evaluated as poor. Table 2 shows the results
It described in. It can be seen that the magnetic disk of the present invention has extremely excellent running durability even when a floppy disk having a very smooth surface and a thin protective film is used. Further, it can be seen that the running durability is far superior to the case of using perfluoropolyether alone which is generally used for a hard disk.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

The magnetic disk of the present invention has excellent running durability even when a floppy disk having a very smooth surface and a thin protective film is used, and a specific organic acid and amine are combined. Used to form a lubricant layer,
Compared with the case of using only perfluoropolyether generally used for hard disks, a magnetic disk having much better running durability can be obtained.

Claims (5)

[Claims] 1. A rotational speed of 100 in which a magnetic film made of a ferromagnetic metal thin film is formed on at least one surface of a flexible support.
In a magnetic disk for a magnetic recording system in which recording and reproduction are performed at 0 rpm or more, lubrication comprising a carboxylic acid having at least a fluoroalkyl chain and an alkyl chain in a molecule on the magnetic film or a protective film formed on the magnetic film. A magnetic disk comprising an agent. 2. The magnetic disk according to claim 1, wherein the lubricant contains an alkylamine. 3. A rotation speed of 100 in which a magnetic film made of a ferromagnetic metal thin film is formed on at least one surface of a flexible support.
In a magnetic disk for a magnetic recording system in which recording and reproduction are performed at 0 rpm or more, a lubricant comprising a carboxylic acid having at least two fluoroalkyl chains in a molecule on the magnetic film or on a protective film formed on the magnetic film A magnetic disk comprising: 4. The magnetic disk according to claim 1, wherein the lubricant contains an alkylamine. 5. The magnetic recording system according to claim 1, wherein the magnetic disk according to claim 1 is rotatably housed in a cartridge having a liner on an inner surface thereof. Disk cartridge.