JP2001189007A - Magnetic disk and method of magnetic recording by using floppy disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic disk having high hardness and low coefficient of friction and a magnetic recording method which uses a floppy (R) disk. SOLUTION: In the magnetic disk produced by laminating a magnetic film, protective film and lubricant film on at least one surface of a flexible nonmagnetic supporting body, the protective film consists of a carbon film containing hydrogen, nitrogen and rare gas elements and has 0.5 to 8.0 atomic % nitrogen content and 0.5 to 1.2 atomic % content of rare gas elements. In the magnetic recording method which uses a floppy disk, magnetic signals are recorded and reproduced in a floppy disk device equipped with a head or a slider having a carbon protective film on its surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic recording medium having a high areal recording density and a magnetic recording system using a large-capacity floppy disk having sufficient practical reliability.

[0002]

2. Description of the Related Art In a magnetic recording medium such as a magnetic tape or a hard disk, a magnetic tape such as a vapor-deposited tape or a metal thin-film hard disk having a recording layer of a ferromagnetic metal thin film produced by a vacuum film forming method such as a sputtering method or a vapor-depositing method. Recording media have been put to practical use. In such a magnetic recording medium,
Since high magnetic energy can be easily obtained and smooth surface properties can be easily achieved by smoothing the surface of the non-magnetic substrate, there is a feature that the spacing loss is small and high electromagnetic conversion characteristics can be obtained. It is suitable for a method for producing a high-density recording material. In particular, the sputtering method can increase the magnetic energy further than the vapor deposition method, and is therefore used for a magnetic recording medium such as a hard disk, which requires a high surface recording density.

On the other hand, floppy disk type magnetic recording media have been widely used mainly in the 2HD class because of their excellent impact resistance and low cost as compared with hard disks. Zi using coating technology
High-density magnetic recording media such as p (Iomega) are also used. In such a magnetic recording medium, 3
By performing recording and reproduction at a high speed of about 000 rpm, a high-speed transfer speed close to that of a hard disk is achieved. However, the recording density is still less than 1/20 that of a hard disk. This is largely due to the fact that a floppy disk type magnetic recording medium, such as a hard disk, in which a magnetic layer is formed by a sputtering method has not yet been put to practical use. There are various reasons for this,
One of the reasons is that it is difficult for such a magnetic recording system using a floppy disk to secure sufficient running durability and obtain practical reliability.

The reason that it is more difficult to secure the durability of a floppy disk for producing a magnetic film by a sputtering method than to a floppy disk produced by a conventional coating method is that a floppy disk produced by a coating method is a magnetic film. In addition to magnetic particles, it contains hard fine particles and a lubricant, so it has excellent lubricity and wear resistance.On the other hand, floppy disks made by the sputtering method use a thin metal film whose magnetic film is easily worn. Because there is. Therefore, like a hard disk, a wear-resistant protective film on a magnetic film,
Further, studies have been made to form a lubricating film thereon to enhance lubricity and wear resistance. However, even if a protective film or a lubricating film similar to such a hard disk is formed on a floppy disk, although sufficient effect of improving running durability is obtained, sufficient practical reliability cannot always be obtained. In the case of a hard disk, when the rotational speed of the disk is increased, the head floats due to the effect of the floating force acting on the head, and the head is used in a state where the hard disk does not come into contact. Even if it is increased, the vibration of the disk (runout) is large, so that the head cannot float stably, and the head and the floppy disk frequently come into contact even at high speed rotation.

Therefore, in order to increase the running durability of a floppy disk and secure practical reliability, (1) a lubricating film having excellent lubricating properties, (2) a protective film having excellent abrasion resistance, and (3) a head and a disk contacting each other. Controlled surface roughness that does not generate high frictional force (4) It is necessary to secure a small surface runout to reduce the frequency of contact. In particular, a lubricating film and a protective film are required to have higher durability in contact sliding than those used in a hard disk.

[0006] As a protective film having excellent wear resistance, there is a non-conductive film made of carbon and hydrogen called diamond-like carbon (DLC) used as a protective film for a videotape having a metal thin film type magnetic layer formed by a hard disk or vapor deposition. Amorphous carbon films are most common. Diamond-like carbon has excellent characteristics such as being relatively easy to produce, hard and low in frictional force, and less likely to cause seizure. However, it was found that sufficient durability could not be obtained even when commonly used diamond-like carbon containing carbon and hydrogen was used as a protective film for a floppy disk. This is because when diamond-like carbon is used as a protective film, the frictional force gradually increases due to repeated contact between the head and the disk, causing breakage of the diamond-like carbon film or the magnetic film, causing scratch-like scratches. It is thought to occur. In order to suppress the increase in frictional force, various improvements such as the structure of the lubricant, the adsorptivity between the lubricant and the protective film, the surface treatment of the protective film, and the characteristics of the protective film can be considered. In order to maintain a low frictional force even if it is somewhat worn or worn, reduction of the friction coefficient of the protective film itself is considered to be the most effective method.

For example, as a method of modifying the protective film of a hard disk, there is a method of adding a third element in addition to carbon and hydrogen constituting diamond-like carbon. Among them, nitrogen-added diamond-like carbon in which nitrogen is added is used. It is reported that it has an effect of reducing frictional force. For example, JP-A-7-334830 and JP-A-1-320622 describe that a diamond-like carbon film containing nitrogen is used as a protective film. Also, JP-A-6-3
No. 33231 describes that a protective film containing hydrogen and nitrogen and a lubricant layer having a polar group are provided. US Pat. No. 5,567,512 (JP-A-8-106629) discloses that the surface density of nitrogen atoms is reduced. A carbon protective film having a specified ratio is described. Further, Japanese Patent Application Laid-Open No. 9-28881
No. 8 describes that a carbon protective film containing nitrogen and having a thickness of 10 to 20 nm is provided, and Japanese Patent Application Laid-Open No. 10-143836 discloses that the nitrogen concentration in the carbon protective film is increased. It describes that a substance having a specific chemical structure is used as a lubricant while being changed in a vertical direction. Further, US Pat. No. 5,776,602 describes a nitrogen-containing carbon protective film having a Raman spectrum in a specific range, and EP 54720 describes a film containing hydrogen and nitrogen having a thickness of more than 20 nm. It is described that a thin carbon protective film is provided.

On the other hand, the disk slides with the floppy disk.
Magnetic heads generally control flying and contact conditions
It is mounted on a slider. Floppy disk
Slider is used for hard disk drive
Al as well as the slider _TwoO_Three-Ceramics such as TiC
Made by the box, Japanese Patent Laid-Open No. 8-45045
Hard disk drive slurs described in publications
Like a slider, a carbon protective film is formed on the slider surface.
Not. This is a conventional thin-film coated floppy disk
When using as a magnetic recording medium, a hard carbon protective film
This protective film slides with the floppy disk even if
Wears out in a short time, and the effect is very small.
The cause is thought to be.

The surface of the slider of the hard disk drive is made to float stably by the air flow generated by the rotation of the disk. However, unlike the case of the hard disk, it is difficult to obtain a stable floating of the floppy disk unlike the hard disk. Therefore, it is manufactured to have very slight contact sliding. Therefore, not only the wear of the medium but also the wear of the head and the slider are very important in evaluating the reliability of the system. If the head wears, it becomes difficult to read / write.If the slider wears, the powder generated by the wear enters between the head and the disk, causing a reading error when reading the recording signal, and furthermore, the floppy disk cannot be read. Causes damage such as scratching. The problem of disk and head wear as described above is very important in securing practical reliability in the case of a magnetic recording system using a large-capacity floppy disk whose recording density has been improved compared to the conventional floppy disk system. This problem has been very difficult to solve, especially when trying to use a metal thin film type floppy disk as the floppy disk. Therefore, the present invention solves this problem.
It is an object of the present invention to secure sufficient practical reliability in a magnetic recording system using a high-density floppy disk using a metal thin-film type floppy disk. Further, it was found that sufficient durability could not be obtained even when general diamond-like carbon was used as a protective film for a floppy disk. This is when diamond-like carbon is used as the protective film,
It is considered that the friction between the head and the disk repeatedly increases gradually, causing the diamond-like carbon film or the magnetic film to break, leading to scratching.

In order to suppress the increase in the frictional force, various methods for improving the structure of the lubricant, the adsorptivity between the lubricant and the protective film, the surface treatment of the protective film, and the characteristics of the protective film are considered.
It is considered that the reduction of the coefficient of friction of the protective film itself is the most effective method for maintaining a low frictional force even when the lubricant and the protective film are somewhat worn and worn. However, it has been found that, in many cases, when nitrogen is added to diamond-like carbon in a protective film of a floppy disk, although the friction coefficient certainly decreases in many cases, the running durability often decreases. This is presumably because the friction coefficient is reduced due to the difference in the manufacturing conditions and the nitrogen content, but the hardness is reduced and sufficient wear resistance is not obtained.

Normally, when nitrogen is added to diamond-like carbon, the frictional force gradually decreases (improves) and the hardness gradually decreases (deteriorates) with an increase in the amount of nitrogen added. Therefore, in order to ensure sufficient running durability under severe sliding conditions such as a floppy disk, it is necessary to produce a protective film having an appropriate composition and structure to achieve both a sufficient hardness and a friction coefficient. To cope with such a problem, a method of laminating relatively soft nitrogen-added diamond-like carbon on hard diamond-like carbon has also been proposed, but there is a problem that the manufacturing process becomes complicated. The problem of disk and head wear is very important for magnetic recording using a large-capacity floppy disk with a higher recording density than conventional floppy disk systems, in order to ensure practical reliability. It was very difficult to solve this problem when trying to use a metal thin film type floppy disk.

[0012]

SUMMARY OF THE INVENTION In the present invention, a protective film having both a high hardness and a low coefficient of friction is manufactured, and not only the one using a rigid support such as a hard disk but also the severe sliding such as a floppy disk. It is an object of the present invention to provide a magnetic recording medium having sufficient running durability even when used under conditions. It is another object of the present invention to provide a magnetic recording medium having a protective film having both high hardness and a low coefficient of friction, and capable of obtaining excellent running durability in both hard disks and floppy disks. It is. Another object of the present invention is to secure sufficient practical reliability in a magnetic recording system using a high recording density floppy disk using a metal thin film type floppy disk.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic disk having a structure in which a magnetic film, a protective film and a lubricating film are laminated on at least one surface of a flexible support. And a magnetic disk containing nitrogen. In a magnetic disk having a structure in which a magnetic layer, a protective film, and a lubricating film are laminated on at least one surface of a flexible support or a rigid support, the protective film contains at least carbon, hydrogen, nitrogen, and a rare gas element. It is a magnetic disk. The magnetic disk according to the above, wherein the nitrogen content of the protective film is 0.5 to 8.0 atm%. Further, in the above magnetic disk, the protective film has a hydrogen content of 25 to 35 atm%. The magnetic disk according to the above, wherein the carbon content of the protective film is 60 to 70 atm%.
The magnetic disk according to the above, wherein the protective film has a rare gas element content of 0.5 to 1.2 atm%.

In the method for manufacturing a magnetic disk,
After a magnetic film is formed on at least one surface of a flexible support or a rigid support, a plasma using a mixed gas of hydrocarbon, nitrogen, and rare gas as a raw material is applied while a negative bias is applied to the magnetic film. This is a method for manufacturing a magnetic disk in which a protective film is formed on the surface of a magnetic film by a CVD method. This is a method for manufacturing a magnetic disk, wherein the magnetic film is formed by a sputtering method.

Further, according to the present invention, in a magnetic recording system using a floppy disk, a magnetic recording medium comprises a floppy disk having a ferromagnetic metal thin film and a carbon protective film laminated on at least one of a flexible support and a head. Alternatively, a magnetic recording system using a floppy disk for recording and reproducing a magnetic signal with a floppy disk device provided with a carbon protective film on a slider surface. In the above magnetic recording system using the floppy disk, the hardness of the carbon protective film of the floppy disk is lower than the hardness of the carbon protective film on the surface of the head or the slider. The microhardness of the carbon protective film of the floppy disk is in the range of 20 GPa to 40 GPa, the microhardness of the carbon protective film on the surface of the head or the slider is 30 GPa or more, and the hardness of the carbon protective film of the floppy disk is the surface of the head or the slider. The magnetic recording system using the floppy disk having a hardness lower than that of the carbon protective film.

In a magnetic recording system using a floppy disk, a ferromagnetic metal thin film is provided on at least one of the flexible supports, and a carbon protective film containing at least carbon, hydrogen and nitrogen is provided on the ferromagnetic metal thin film. The above-mentioned magnetic recording method using a floppy disk characterized in that the laminated floppy disk is used as a magnetic recording medium, and recording and reproduction of a magnetic signal is performed by a floppy disk device provided with a carbon protective film on the head or slider surface. is there.
Hydrogen content of carbon protective film of floppy disk is 25 ~
The above magnetic recording method using a floppy disk having a nitrogen content of 0.5 to 8.0 atm% at 35 atm%. The above magnetic recording system using the above floppy disk wherein the carbon protective film of the floppy disk contains at least carbon, hydrogen, nitrogen and a rare gas element.
The carbon protective film of the floppy disk is at least carbon,
Contains hydrogen, nitrogen and a rare gas element, and has a hydrogen content of 25 to 35 atm% and a nitrogen content of 0.5 to 8.0 a.
tm% and a rare gas element content of 0.5 to 1.2 atm%.

In a magnetic recording system using a floppy disk, at least one of the flexible supports has a ferromagnetic metal thin film, and a carbon protective film containing at least carbon, hydrogen and nitrogen on the ferromagnetic metal thin film. A magnetic recording method using a floppy disk that records and reproduces a magnetic signal in a floppy disk device having a carbon protective film containing at least carbon and hydrogen on the surface of a head or a slider while using a floppy disk on which magnetic layers are laminated as a magnetic recording medium It is. The hydrogen content of the carbon protective film of the floppy disk is 25-35 atm%, and the nitrogen content is 0.5-8.
This is a magnetic recording method using the above-mentioned floppy disk of 0 atm%. This is a magnetic recording system using the above-mentioned floppy disk in which the carbon film protective film of the floppy disk contains at least carbon, hydrogen, nitrogen and a rare gas element. The carbon protective film of the floppy disk contains at least carbon, hydrogen, nitrogen and palladium gas elements, and has a hydrogen content of 25 to 35 atm% and a nitrogen content of 0.5 to 8 atm.
0 atm%, rare gas element content is 0.5 to 1.2 atm
% Is a magnetic recording system using the above floppy disk. The micro hardness of the carbon protective film of the floppy disk is in the range of 20 GPa to 40 GPa, and the micro hardness of the carbon protective film on the surface of the head or the slider is 30 GPa.
This is a magnetic recording method using a floppy disk, wherein the hardness of the carbon protective film of the floppy disk is lower than the hardness of the carbon protective film on the surface of the head or the slider.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The magnetic disk of the present invention has a feature in a protective film. The protective film is made of carbon, hydrogen, and nitrogen. Preferably, it further contains a rare gas element. Further, the protective film preferably has a nitrogen content of 0.5 to 8.0 atm%, a hydrogen content of 25 to 35 atm%, and a carbon content of 60 to 70 atm.
m% and a rare gas element content of 0.5 to 1.2 atm%. With the contents of these elements, the hardness and the friction coefficient can be made compatible at an extremely high level. These element contents can be measured by a known method such as Rutherford backscattering method. Below this, the coefficient of friction increases, above which the hardness decreases significantly. More preferable content is 2-5a
tm%. If the amount of the rare gas element is less than this, the hardness decreases, and if it is more than this, the internal stress increases and the film is liable to peel. More preferably, the content is 0.5
~ 1.0 atm%. Less or more carbon will reduce hardness. More preferably, the content is 64 to
67 atm%. If the amount of hydrogen is smaller than this, the hardness decreases, and if it is larger, the coefficient of friction increases. More preferably, the content is 28 to 33 atm%.

A feature of the present invention is that both high hardness and low coefficient of friction can be achieved. Hardness is strongly affected by the base material in thin films actually used as a protective film,
It cannot be measured accurately. Therefore, in general, a protective film having a thickness of about 0.1 to 1 μm is formed on a uniform and somewhat hard substrate such as a single crystal silicon substrate, and a microhardness tester to which an atomic force microscope (AFM) is applied is used. The hardness is measured under such conditions that the indentation depth is 1/5 or less of the film thickness. For example, as an example of such a microhardness tester, a pickup electrode with an indenter placed between two electrode plates is used. There is a method of measuring displacement by a method of detecting displacement with very high sensitivity. More specifically, a micro-hardness measuring device (TRIBOS manufactured by HYSITRON) will be described below.
(COPE) will be described. The diamond indenter has a tip angle of 90 degrees and a tip curvature radius of 35 to 5.
0nm triangular pyramid, applied to protective layer at right angle, maximum load P
= 600 μN, and the load is gradually returned to 0 after reaching the maximum load. The value P / A obtained by dividing the maximum load P at this time by the projected area A of the indenter contact portion is calculated as the hardness. The projected area A of the indenter contact portion is an initial 30% of the unloading curve among the depth-load curves obtained by the indentation test.
Is approximated as a straight line and extrapolated, and the point of intersection with the depth axis is defined as the contact depth h of the indenter contact portion, and is obtained as a function of h from the shape of the indenter. In addition, the apparatus was calibrated and measured in advance so that the hardness obtained as a result of pressing the fused quartz as a standard sample was 8 to 10 GPa. The protective film of the present invention has a hardness of 30 to 40 GPa as measured by such a measuring method, and the hardness of the protective film made of carbon, hydrogen, and nitrogen produced by the reactive sputtering method is significantly higher than 20 to 30 GPa. It is a feature.

On the other hand, the coefficient of friction can be measured in the form of a magnetic recording medium. The measurement may be performed by measuring the frictional force with the actual magnetic head, or may be performed in the form of a ball-on-disk or a pin-on-disk as a substitute evaluation. In particular, the effect of the present invention appears in the friction coefficient when sliding repeatedly at one location, and the sliding force is such that a general DLC film gradually increases the frictional force due to repeated sliding and causes scratching. Even under dynamic conditions, a low frictional force can be maintained for a long period of time. Further, even under the condition that the protective film having a low coefficient of friction and having a high nitrogen content gradually wears, the protective film of the present invention hardly wears, and the protective film of the magnetic disk of the present invention has a magnetic property on at least one of the nonmagnetic support. After the film is formed by the sputtering method, in a state where a negative bias is applied to the magnetic film, mainly carbon, hydrogen, and the like are formed on the surface of the magnetic film by a plasma CVD method using a mixed gas of hydrocarbon and nitrogen as a raw material.
A protective film made of nitrogen is produced, and a lubricating film is further produced on this surface. The protective film produced by this method
It has higher hardness than a similar protective layer formed by reactive sputtering, and can significantly improve the running durability of a magnetic disk.

In the manufacturing method of the present invention, a negative bias is applied to the magnetic film to enhance the etching effect by hydrogen ions and rare gas ions generated by the decomposition of hydrocarbons in the reaction gas. Can be produced. Since the bias applied to the magnetic film varies depending on the device,
Although it is not decided, -100V to -500V
It is about. The bias to be applied has an optimum value, and if the bias is too high, the rare gas content in the protective film increases,
The internal stress of the protective film is increased, and the film is easily peeled. Conversely, if the bias is too low, the etching effect is reduced, so that the contents of hydrogen and nitrogen in the film are increased, and the hardness is significantly reduced. Further, when a positive bias is applied to a position facing the substrate with the plasma interposed therebetween to increase the bias gradient, the effect of applying the bias is more easily obtained.

The raw material gas used for producing the protective film of the present invention includes hydrocarbons composed of carbon and hydrogen such as ethylene, acetylene, methane, ethane, benzene and toluene, and rare gases such as nitrogen and argon and helium. Is used. The content of carbon and hydrogen in the hydrocarbon gas greatly affects the properties of the protective film. For example, when the ratio of hydrogen to carbon is high, such as methane, the hydrogen content in the film increases, and the hardness may not be sufficiently high. Conversely, if the ratio of hydrogen to carbon is low, as in acetylene, the nitrogen content may be too high, or the hardness of the film may not be sufficiently increased due to high organicity of the film. Therefore, it is preferably a raw material such as ethylene having a hydrogen / carbon ratio of about 2/1. The mixing ratio of the raw materials is 5/5 to hydrocarbon / nitrogen ratio.
About 9/1 is preferable. When the amount of hydrocarbons is larger than this, the nitrogen content decreases, and the effect of reducing the friction coefficient decreases.
If the nitrogen content is higher than this, the nitrogen content increases, and the hardness decreases. Further, the ratio of (hydrocarbon + nitrogen) / rare gas is preferably about 1/1 to 1/3. If the ratio of the rare gas is less than this, the etching effect is reduced, the hardness is not sufficiently increased, and if the amount of the rare gas is more than this, In addition, the content of the rare gas in the film increases, and the film is easily peeled. Noble gases that can be used include helium, neon, argon, krypton, xenon, etc., but preferably argon, neon,
Helium, more preferably argon. The method for generating plasma in the present invention is not particularly limited, and high-frequency plasma, ECR plasma, or the like can be used.

FIG. 1 is a view for explaining an example of a CVD apparatus utilizing high-frequency plasma. The support 2 having the metal thin film 1 formed on its surface is unwound from a roll 3, and a bias voltage is supplied to the metal thin film 1 from a bias power supply 5 by a pass roller 4. On the other hand, the source gas 6 containing hydrocarbons, nitrogen, rare gas, etc., is converted into carbon containing nitrogen, rare gas on the metal thin film on the film forming roll 8 by plasma generated by the voltage applied from the high frequency power supply 7. The protective film 9 is formed, and is wound up by a winding roll 10.

At the time of film formation, the substrate temperature for forming the protective film is preferably slightly higher at room temperature than at a higher temperature because the substrate is hardly damaged by heat. Although the protective film of the present invention has excellent adhesion to a magnetic film, high adhesion can be ensured by cleaning the surface of the magnetic film by a glow treatment with a rare gas or a hydrogen gas before forming the protective film. Further, if a silicon intermediate layer is formed on the surface of the magnetic film, the adhesion can be further improved. It is considered that the protective film of the present invention obtained by the above manufacturing method has a structure in which a part of hydrogen of an extremely hard amorphous hydrogenated carbon film is replaced with nitrogen. It can be known by Raman spectroscopy that the basic structure of the film is the same as that of diamond-like carbon. When the Raman spectrum of the diamond-like carbon film is examined, a broad peak is observed at a Raman shift of 1000 to 1800 cm ⁻¹ , and this peak is 1540 c
It is known that a main peak called G peak at m ^-1 and a shoulder called D peak at 1390 cm ^-1 are formed. The Raman spectrum of the protective film of the present invention is also the same as that of the aforementioned DL.
A spectrum similar to the Raman spectrum of C is shown. sp
It is said that the ratio of ³ structure and sp ² structure is reflected |
The d / 1g ratio is 1.10 to 1.60 in the protective film of the present invention,
The G peak protection wave number, which is said to reflect the sp crystallite size, is a general value of 1540 to 1560 cm ^-1 . On the other hand, the ratio B / A of the G peak intensity B including the background, which is said to reflect the organic nature of the film, and the G peak intensity A not including the background is as low as 1.25 to 1.25. Is low.

In the protective film of the present invention, nitrogen is mainly sp3
Alternatively, it may be bonded to sp2 carbon and exist in the film in a stable state by an X-ray photoelectron spectrometer (ESCA X
PS) and the FT-IR method. The C≡N bond found in a film having a nitrogen content of 20 atm% or more formed by a sputtering method is below the detection limit, and it is considered that such a bond does not exist. The density of the protective film of the present invention is 1.7 to 2. lg / cm ³ and high density. The density can be obtained from the atomic number density of Rutherford backscattering method. The protective film of the present invention has a thickness of 3 to 20 n.
It is preferred to use m. If the film thickness is smaller than this, the effect as a protective film does not appear, and if it is larger than this, electromagnetic conversion characteristics as a magnetic recording medium deteriorate due to magnetic spacing, which is not preferable. Further, the protective film of the present invention has a feature that it is more excellent in durability as a thin film of 10 nm or less than a protective film formed by a general reactive sputtering method.

Hereinafter, a preferred embodiment of a floppy disk, which is a magnetic disk using a flexible support, will be described. However, in the present invention, a rigid support can also be used as a nonmagnetic support. When used in the form of a hard disk, a disk-shaped substrate made of aluminum, glass, steel, silicon, polycarbonate or the like can be used. When the tape is used as a video tape or the like, a flexible polymer film having a thickness of 3 to 20 μm such as polyethylene terephthalate, polyethylene naphthalate, a polyimide film, or a polyamide film can be used. When used in the form of a floppy disk, a flexible polymer film having a thickness of 20 to 100 μm such as polyimide, polyamide, or polyethylene naphthalate can be used. In order to ensure high electromagnetic conversion characteristics, the surface roughness of the magnetic film surface is preferably 2 nm or less in Ra, and the maximum surface roughness Rmax is preferably 60 nm or less.

The floppy disk of the present invention has a web shape,
Sheet and disk-shaped raw floppy disks are punched into donut-shaped disks for use. At this time, the size of the disk is 1.8 type, 2.5 type, 3.5 type,
Any size such as 3.7 type, 5 type, etc. can be used. The disk thickness used in the present invention is 20 to 10
0 μm, more preferably 30 μm
８０80 μm. When the thickness is less than 30 μm, the amount of static curl and deformation increases, and when the thickness is more than 80 μm, the impact when the head and the disk come into contact cannot be reduced.

However, when the surface property of the magnetic film surface of the polyimide film or the aramid film is not as smooth as the above-mentioned films, it is necessary to first prepare an undercoat film for the purpose of smoothing on the magnetic film surface of the film. In this case, it is preferable to use a thermosetting imide or a thermosetting silicone resin having a high smoothing effect as a material of the undercoat film. The thickness of the undercoat film is preferably 0.1 to 3 μm. The thermosetting resin can be produced, for example, by a method of applying a silane coupling agent having an epoxy group or a monomer containing a thermosetting imide, followed by thermosetting. This thermosetting imide refers to a monomer having an imide structure and a polymerizable terminal group in the molecule. This monomer is polymerized by heating to form a polyimide structure and thus has excellent heat resistance. Since this thermoplastic imide is in a monomer state before bonding, it can be dissolved in many types of solvents and is soluble in many common solvents. Therefore, drying of the solvent is easy. Furthermore, since the solution viscosity is low and precise filtration is possible, contamination of foreign matters is small. As such a thermosetting imide, for example, bisallylnadiimide represented by the following chemical formula 1 is particularly effective.

[0029]

Embedded image

However, R ¹ and R ² are independently selected hydrogen or methyl groups, and R ³ is a divalent linking group such as an aliphatic or aromatic hydrocarbon group. In the compound represented by the chemical formula 1, R ¹ and R ² are independently selected hydrogen or a methyl group, and R ³ is a divalent linking group such as an aliphatic group or an aromatic group. Examples include an alkylene group and an alkenyl group, a cycloalkylene group, a cycloalkylene group having an alkylene group, an aromatic group, an aromatic group having an alkylene group, a polyoxyalkylene group, a carbonyl group, an ether group, and the like. Such compounds are disclosed in JP-A-59-80662 and JP-A-60-1788.
No. 62, Japanese Unexamined Patent Application Publication No.
Known compounds synthesized by a known synthesis method described in, for example, JP-A-3-170358 and JP-A-7-53516 can be used. Such compounds are commercially available from Maruzen Petrochemical Company as BANI series and ANI series.

As is well known, by providing micro projections having a very low height on the surface of the medium, the real contact area between the medium and the sliding member can be reduced and the sliding characteristics can be improved. It is particularly preferable that the magnetic film surface has a minute projection structure. As a method of producing such a fine projection structure, a method of applying spherical silica particles, a method of applying an emulsion to form organic projections, and the like can be used, but silica particles are preferable in order to ensure heat resistance. It is also possible to use a binder to fix the projections to the film surface, but a resin having sufficient heat resistance is preferable to ensure heat resistance. Examples of such a material include thermosetting imide and thermosetting resin. It is particularly preferable to use a functional silicone resin. The height of the microprojections is 5-6
0 nm, preferably 10-30 nm, and the density is 0.1-100 / μm ² , preferably 1-30 / μm ² .
m ² . If the height of the minute projections is too high, the electromagnetic conversion characteristics are degraded by the spacing between the recording / reproducing head and the medium, and if the height of the minute projections is too low, the effect of improving the sliding characteristics is reduced. If the density of the fine projections is too low, the effect of improving the sliding characteristics is reduced. If the density is too high, the number of high projections increases due to the increase in aggregated particles, and the electromagnetic conversion characteristics deteriorate. The thickness of the coating film of the binder is preferably 20 nm or less. If the binder is too thick, it may adhere (block) to the back surface of the film after drying.

As the ferromagnetic metal thin film serving as the magnetic layer in the magnetic disk of the present invention, a thin film formed by a conventionally known sputtering method can be used. The composition includes a conventionally known metal or alloy mainly composed of cobalt, and specifically, Co-Cr, Co-Ni-Cr, Co-
Cr-Ta, Co-Cr-Pt, Co-Cr-Ta-P
t, Co-Cr-Pt-Si, Co-Cr-Pt-B, etc. can be used. In particular, in order to improve the electromagnetic conversion characteristics, Co
-Cr-Pt and Co-Cr-Pt-Ta are preferred. It is desirable that the thickness of the magnetic layer be 10 to 30 nm. In this case, it is preferable to provide a base film for improving the magnetostatic characteristics of the magnetic film. The base film may be composed of a conventionally known metal or alloy, specifically, Cr, V, Ti , Ta, W, Si and the like or alloys thereof can be used. Among them, Cr, Cr-Ti and Cr-V are particularly preferable. The thickness of the underlayer is 5 nm to 50 nm.
And preferably <10 nm to 30 nm. Further, in order to control the crystal orientation of the underlayer, it is preferable to use a seed layer under the underlayer.
o, W, V, Zr, Cr, Rh, Hf, Nb, Mn, N
i, Al, Ru, Ti or an alloy thereof, particularly preferably Ta, Cr, Ti or an alloy thereof, and has a thickness of 15 to 60 nm. When a magnetic film is formed by a sputtering method, it is preferable to form the film while the substrate is heated, and the temperature at that time is about 200 ° C.

In the magnetic disk of the present invention, in order to improve running durability and corrosion resistance, it is necessary to form a lubricating film and a rust preventive on the protective film. As the lubricant, known hydrocarbon-based lubricants, fluorine-based lubricants, extreme pressure additives and the like can be used. Stearic acid, as a hydrocarbon-based lubricant
Carboxylic acids such as oleic acid, esters such as butyl stearate, sulfonic acids such as octadecylsulfonic acid, phosphoric esters such as monooctadecyl phosphate, alcohols such as stearyl alcohol and oleyl alcohol, and carboxylic acids such as stearamide. Examples thereof include acid amides and amines such as stearylamine.

Examples of the fluorine-based lubricant include lubricants in which part or all of the alkyl group of the hydrocarbon-based lubricant is substituted with a fluoroalkyl group or a perfluoropolyether group. Examples of the perfluoropolyether group 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 in which a fluorine or fluorinated alkyl group is introduced into a phosphazene ring is thermally and chemically stable and can be used. As extreme pressure additives, phosphoric esters such as trilauryl phosphate, phosphites such as trilauryl phosphite,
Examples include thiophosphites such as trilauryl trithiophosphite and the like, thiophosphoric esters, and sulfur-based extreme pressure agents such as dibenzyl disulfide. The above lubricants are used alone or in combination of two or more. As a method of applying these lubricants on the protective film, the lubricant is dissolved in an organic solvent,
It may be applied by a wire bar method, a gravure method, a spin coating method, a dip coating method, or the like, or may be applied by a vacuum evaporation method. The amount of lubricant to be applied is 1 to 30 mg / m
² is preferable, and 2 to 20 mg / m ² is particularly preferable.

Examples of the rust preventives usable in the present invention include nitrogen-containing heterocycles such as benzotriazole, benzimidazole, purine and pyrimidine, derivatives having an alkyl side chain introduced into their mother nucleus, benzothiazole, 2-mercapto And nitrogen- and sulfur-containing heterocycles such as benzothiazole, tetrazaindene ring compounds and thiouracil compounds, and derivatives thereof. The tetrazaindene ring compounds that can be used for such purposes include the following.

[0036]

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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 to 20 carbon atoms, and in the case of alkoxy, R of ROCOCH ₂ — is C ₃ H ₇ —, C _3
6 H _13- , phenyl or, in the case of an alkyl group, C ₆ H
_{13 -, C 9 H 19 -} , C 17 H 35 - , and the like, in the case of alkylamide RNHCOCH ₂ - of R phenyl, C ₃
H ₇ -, and the like. Further, examples of the thiouracil ring compound include the following. However, R is selected from the same as those in the above-mentioned tetrazaindene ring compound.

[0038]

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When the medium of the present invention is used as a floppy disk, the disk is used in a state of being incorporated in a cartridge as is well known. It is very important not only to prevent the attachment of dirt from the outside of the cartridge but also to secure the rotational stability of the floppy disk. Further, the magnetic recording system using the floppy disk of the present invention uses a floppy disk having a configuration in which a ferromagnetic metal thin film and a carbon protective film are laminated on at least one of a flexible support as a magnetic recording medium, and On the other hand, this is a magnetic recording system using a floppy disk in which a recording signal is recorded and reproduced by a floppy disk device provided with a carbon protective film on the surface of a head or a slider. The magnetic recording system using the floppy disk achieves high practical reliability by the effect of the combination of the disk and the head. If either one is missing, the effect of the present invention cannot be obtained.

In the magnetic recording system using a floppy disk of the present invention, when the floppy disk and the head or slider are slid in contact with each other, a lubricant is provided between the carbon protective film of the disk and the carbon protective film of the head or slider. It becomes friction in the state that existed. It is known that the friction between some carbons has a very low coefficient of friction and a small amount of wear, and such a good sliding state is achieved by the magnetic recording system using the floppy disk of the present invention. It is considered something. Further, since the lubricant of the floppy disk comes into contact with chemically inert carbon on the surfaces of both the disk and the head, the lubricant is hardly subjected to chemical decomposition, and the lubricating effect can be maintained for a long period of time. In the present invention, when the carbon protective film of the floppy disk is not provided, or when another protective film such as silica is used, the wear of the carbon protective film on the disk surface or the head proceeds, and the disk is damaged or the head output is reduced. Failure easily occurs in a short time. If the head does not have a carbon protective film, or if a protective film such as silica is used, the wear of the carbon protective film of the floppy disk and the decomposition of the lubricant will be remarkable, and the life of the disk will be extremely shortened. There are many.

The effect of the present invention is large when the hardness of the carbon protective film of the floppy disk is smaller than the hardness of the carbon protective film on the surface of the head or the slider. In particular, the micro hardness of the carbon protective film of the floppy disk is 20 to 40 Gpa.
This effect is remarkable when it is in the GPa range and the micro hardness of the carbon protective film on the head or slider surface is 30 GPa or more. When the floppy disk and the head protective film are the same carbon protective film, the wear of the carbon protective film progresses, although it is very slight, and the sliding time in the same part after a long-term use is relatively shorter than that of the disk. In some cases, the protective film of the long head may be worn away before the disk and disappear. Therefore, by making the hardness of the head protective film higher than the hardness of the floppy disk protective film, the life of the head protective film can be extended.

Further, when the microhardness of the carbon protective film of the floppy disk is in the range of 20 GPa to 40 GPa and the microhardness of the carbon protective film on the surface of the head or the slider is 30 GPa or more, each of the protective films has a sufficient resistance. Since the wearability can be achieved, the practical reliability of the floppy disk can be significantly improved. If the microhardness of each protective film is less than 20 GPa, the wear resistance of the protective film may increase due to insufficient wear resistance, and the life of the floppy disk may be shortened. If the microhardness of the protective film of the floppy disk is set to be larger than 40 GPa, the life of the protective film of the head may be shortened, or the magnetic film may be separated due to an increase in the coefficient of friction.

As the carbon protective film used for the head or slider of the present invention, the same carbon protective film formed on the magnetic recording medium can be used. In particular,
A general amorphous carbon film, graphite film, diamond film, or the like can be used. Above all, an amorphous carbon film called a diamond-like carbon film (DLC film) can easily form a high-hardness protective film and can easily control properties such as hardness and friction coefficient depending on manufacturing conditions. It is suitable as a carbon protective film. The protective film of the head or the slider of the present invention is preferably a diamond-like carbon film or a diamond film among carbon films, and more preferably a diamond-like carbon film.

The hardness of the protective film of the head or the slider is preferably higher than the hardness of the protective film of the floppy disk. By adjusting the hardness in this manner, the life of the protective film of the head can be extended. Further, the hardness of the protective film of the head or the slider is preferably 30 GPa or more. The thickness of the protective film is preferably from 1 nm to 30 nm when the film thickness is large, since the electromagnetic conversion characteristics are deteriorated and the adhesion is deteriorated when the film thickness is large, and the wear resistance is insufficient when the film thickness is small.
m to 10 nm is particularly preferred. A particularly preferred head or slider protective film is composed of carbon, hydrogen, and a rare gas element, and has a carbon content of 50 to 80 atm%, a hydrogen content of 20 to 50 atm% and a rare gas content of 0.5.
１．２1.2 atm%. These Motohata contents can be measured by a known method such as Rutherford backscattering method. Hydrogen content is 2
If it is less than 0 atm%, the hardness decreases, and if it is more than 50 atm%, the friction coefficient increases. A more preferred content is 3
5 to 45 atm%. Further, when the rare gas element is 0.5
If it is less than atm%, the hardness is reduced, and if it is more than 1.2 atm%, the internal stress is increased and the film is easily peeled. A more preferred content is 5 to 1.0 atm%.

As the head used in the magnetic recording system using the floppy disk of the present invention, an inductive head used in a hard disk drive or an MR head using a magnetoresistive element can be used. In order to increase the recording density, it is preferable to use an MR head as the reproducing head. In addition to a general MR head, a G-MR head,
A dual stripe type MR head or the like can be used. Among them, the dual stripe type MR head is suitable for the floppy disk system of the present invention since the occurrence of thermal asperity can be reduced by the structure of the head.

The slider having the head mounted thereon may have the same structure as that used in the hard disk drive. For example, a tapered flat type positive pressure slider or one with a slot in this rail, a tri-pad slider, a negative pressure slider, etc. can be used, and among them, a tapered flat type positive pressure slider or one with a slot in this rail A combination with a floppy disk is preferable because it is less susceptible to disk runout. The slider is, for example, Al ₂ O ₃ —TiC, alumina,
It is produced using ceramics such as zirconia and CaTiO ₃ as materials. When the carbon protective film of the present invention is provided on this slider, it is preferable to provide an intermediate layer of silicon or its oxide or nitride in order to improve the adhesion as described above. The thickness of this intermediate layer is preferably about 1 to 5 nm. The slider can be of a general size used for a hard disk. Above all, from the obedience to disk vibration and the availability,
What is called a nano slider (50% slider) and a picos slider (30% slider) are suitable.

As a method for manufacturing the head and the slider, the head and the slider can be manufactured using the same method as the method for manufacturing the head for the hard disk drive. For example, Al
_A large number of head elements are formed at once on a substrate made of a slider material such as ₂ O ₃ —TiC by a sputtering method or the like, and the slider is cut out from the substrate and washed, and then an adhesion layer and a carbon protective film are formed on the sliding surface of the slider. And a method of forming a surface shape for controlling floating by ion milling or the like. A suspension mechanism composed of a spring-like member or the like for applying a suitable weight to the slider and following the disk vibration may be of the same type as the hard disk drive. Among them, those having an appropriate weight of about 9.8 to 58.8 mN (1 to 6 gf) are suitable. If the weight is less than 9.8 mN, the head easily jumps from the disk, and a dropout of the reproduced signal occurs. Conversely, the weight is 58.8m
A disk heavier than N tends to wear out, shortening the life of the disk. As the head drive mechanism, both a so-called in-line type and a transverse type can be used. If the disk diameter is relatively large such as 3.5 type, the transverse type is preferable. This is because the head window of the shell can be made smaller by using the transverse type head driving mechanism, thereby reducing the disk runout. In the present invention, two heads are used in combination so as to be symmetrical with respect to both sides of the floppy disk.

As the shell forming the floppy disk cartridge of the present invention, ABS resin or the like can be used. Further, in order to protect the internal disk, it is necessary to have a strength that does not significantly deform under an assumed external force. Further, in order to prevent vibration during rotation, it is preferable to have a strength and a structure corresponding to the disk size and the number of rotations. The inner space width formed by the upper shell and the lower shell is 0.5 to 2.0 m
It is preferably in the range of m. If the width is smaller than this, the floppy disk and the shell or liner are in strong contact even during rotation, and the wear of the disk becomes remarkable. If it is wider than this, the effect of restricting the rotation of the disk is reduced.

It is preferable that a liner is provided on the inner surface of the shell in contact with the floppy disk for cleaning the floppy disk and preventing adhesion between the floppy disk and the shell. As the material of the liner, a non-woven fabric containing polyester-based fibers and acrylic-based fibers, mainly cellulose-based fibers such as rayon fibers, polynosic fibers, cupra fibers, and acetate fibers can be used. Further, the liner may contain a rust inhibitor, a lubricant, an antistatic agent, a fungicide, and the like. The rotation speed of the disk in the present invention is 2000 rpm or more, preferably in the range of 2500 rpm to 7200 rpm.
If the number of rotations is too low, the floating force acting on the head is small, the frequency of contact between the disk and the head is significantly increased, the life is shortened, and the data transfer speed required for high-density recording is undesirably reduced. On the other hand, if the rotation speed is too high, the vibration of the disk is not one cycle, and the head cannot follow the disk, so that the error rate deteriorates and the disk is easily worn.

[0050]

The present invention will be described below with reference to examples. Examples 1-1 to 1-20 and Comparative Examples 1-1 to 1-3 Protective films were prepared in the same manner on the sliding property evaluation hard disk, the sliding property evaluation floppy disk, and the hardness measurement sample, respectively. In addition to measuring each component of the protective film, a hardness test was performed for a sample for hardness measurement, and a ball-on-disk test (B
An OD test) and a contact stop-start test (CSS test) were performed, and a friction test and a durability test were performed on the floppy disk.

(Preparation of Hard Disk for Evaluation of Sliding Characteristics)
After heating the aluminum substrate for hard disk on which the Ni-P plating whose surface is mirror-polished was applied to 200 ° C.,
A 30 nm Cr-Ti underlayer was formed by DC magnetron sputtering, followed by a 25 nm Co-Cr-Pt magnetic layer. Further, after this surface was cleaned with argon glow, Example 1 was formed thereon under the film forming conditions shown in Table 1.
18 and Comparative Examples 1 and 2 were formed by high-frequency plasma CVD, and Examples 19 to 20 and Comparative Example 3 were formed by a reactive sputtering method using graphite as a target. Next, a perfluoropolyether-based lubricant (Audimont F.
A solution in which a phosphazene ring compound (OMBL1N Z-DOL) and fluorine introduced (X-1P manufactured by Dow Chemical Company) were dissolved in a fluorine-based solvent (HFE-7200 manufactured by Sumitomo 3M) was filtered through a filter having a pore diameter of 0.1 μm. rear,
A lubricating film having a thickness of 1 nm was formed by applying a dip coating method.

(Floppy Disk for Sliding Characteristics Evaluation) A thermosetting imide resin (BAN1-NB manufactured by Maruzen Petrochemical Co.) was mixed on both sides of a polyimide film having a maximum projection roughness of 200 nm and a thickness of 75 μm on both sides by mixing ethanol and cyclohexanone. The solution dissolved in the solvent was filtered through a membrane filter having a pore diameter of 0.1 μm, applied by a dip coating method, and heated at 250 ° C. for 12 hours to prepare an undercoat film. Further, an organosilica sol having a particle diameter of 18 nm dispersed in cyclohexanone was applied thereon by a dip coating method, and then dried at 250 ° C. for 1 hour to form fine protrusions on the undercoat film surface. The density of these microprojections is 10 /
μm ² . Next, in a state where the support is sandwiched by a holder, the support is installed in a sputtering apparatus for forming a magnetic film,
After heating the support to 200 ° C., a 30 nm thick Cr—Ti underlayer was formed by DC magnetron sputtering, followed by a 25 nm Co—Cr—Pt magnetic film. The base film and the magnetic film were formed on both sides of the support. Further, after the surface of the magnetic film was cleaned by argon glow discharge, Examples 1 to 18 and Comparative Examples 1 and 2 were formed on the magnetic film by the high frequency plasma CVD method under the film forming conditions shown in Table 1 to obtain Examples 19 to 20, In Comparative Example 3, a protective film having a thickness of 20 nm was formed by a reactive sputtering method using graphite as a target. Next, this sample was taken out of the holder, and a perfluoropolyether-based lubricant (FOMBLIN Z-manufactured by Ausimont, Inc.) was placed on the protective film.
DOL) and a phosphazene ring compound (X-1P manufactured by Dow Chemical Co., Ltd.) into which fluorine has been introduced.
HFE-7200 (manufactured by the company) with a pore size of 0.1
After filtration through a μm filter, the mixture was applied by a dip coating method to form a lubricating film having a thickness of 1 nm. Then, this sample was punched into a 3.7-type magnetic disk shape and assembled into a cartridge to produce a floppy disk.

(Sample for Hardness Measurement) After the mirror-polished single crystal silicon substrate was cleaned with argon glow, Examples 1-1 to 18 and Comparative Example 1 were formed thereon under the film forming conditions shown in Table 1.
-1 to 1-2 are high-frequency plasma CVD methods, Examples 1-19 to 1-20, and Comparative Example 1-3 are reactive sputtering methods using graphite as targets, each having a thickness of 0.15 μm. A protective film was formed. The prepared sample was evaluated from the following viewpoints. The results are shown in Table 2.

(Evaluation Method) (1) Evaluation of friction coefficient and durability by ball-on-disk test A ball-on-disk test was performed using Al ₂ O ₃ —TiC balls having a diameter of 1/4 inch as a slider. Weight is 1
0 gf, measurement radius position is 30 mm, disk rotation speed is 6
It was set to 0 rpm. The friction force applied to the slider during the test was measured with a strain gauge, and the friction coefficient was determined. The test was terminated when the coefficient of friction exceeded 0.5, and the test was performed for up to 300 minutes. The test environment was 23 ° C. and 50%. The result is BOD1
The time was expressed in minutes. In addition, a sample that exhibited a durability of 300 minutes or more at 10 gf was similarly tested with a load of 20 gf, and was similarly expressed as BOD2. (2) Durability evaluation by CSS test Tapered flat type Al ₂ O ₃ -T equipped with a magnetic head
Using an iC slider, a CSS test required for a hard disk or the like, that is, a contact stop and start test in which rotation was stopped in a close contact state and then rotation was started in a close contact state was performed. CSS cycle is 0-30
00 rpm acceleration 3 seconds, 3000 rpm maintenance: 10 seconds, 3
The test was performed up to 10,000 cycles with 3 cycles of deceleration of 000 to 0 rpm and 3 seconds of rest as one cycle. Weight is 5g
f, the measurement radius position was 35 mm. The friction force applied to the slider during the test was measured with a strain gauge, and the frictional force during deceleration was 5
The durability was evaluated with the number of cycles exceeding gf. The evaluation environment was 23 ° C. and 50%. In the table, the number of cycles in the measurement results is shown at a magnification of 1000 times.

(3) Measurement of Friction Force of Floppy Disk Friction force of a floppy disk was measured using a floppy disk drive (Zip drive manufactured by Fuji Photo Film Co., Ltd.). With the floppy disk set on the spindle and rotating at 3000 rpm, Zip
A 100 head was pressed from both sides of the disc so as to have a load of 5 gf, and the frictional force applied to the head at this time was measured with a strain gauge. The frictional force was an average value of the frictional force between the upper head and the lower head one minute after the start of traveling. The measurement environment was 23 ° C. and 50% RH. (4) Fixed Track Endurance Test Using Floppy Disk Drive Floppy disk drive: (A running endurance test was performed using a Zip drive manufactured by Fuji Photo Film Co., Ltd. The recording and reproduction of an 8 MHz signal on both sides were repeated at a cycle of 1 minute, and the time required for the reproduction output to attenuate to 16 dB of the initial output was evaluated.
Up to 00 hours. The environment was 23 ° C. and 50% RH. (5) Hardness A sample for hardness measurement was measured using a micro hardness tester (TRIBOSCOPE manufactured by HYSITRON). The diamond indenter used for the measurement was a triangular pyramid with a tip ridge angle of 90 degrees and a tip curvature radius of 35 to 50 nm.
The load is gradually applied up to the maximum load P = 600 μN, and after the maximum load is reached, the load is gradually returned to 0. Maximum load P at this time
Was divided by the projected area A of the indenter contact portion, and the value P / A was calculated as the hardness. The projected area A of the indenter contact portion is obtained by extrapolating the initial 30% of the unloading curve from the depth-load curve obtained by the indentation test by approximating the straight line to a straight line, and setting the point intersecting the depth axis with the indenter contact portion. Is obtained as a function of h from the shape of the indenter. In addition, the apparatus was calibrated and measured in advance so that the hardness obtained as a result of pressing the fused quartz as a standard sample was 8 to 10 GPa. (6) Chemical Composition C, H, N, and rare gas compositions of the hardness measurement samples were examined by using Rutherford backscattering method.

[0056]

[Table 1] Sample Hydrocarbon gas species Nitrogen rare gas species Substrate bias Input power Flow rate Flow rate Voltage (ccm) (ccm) (ccm) (V) (W) Example 1-1 Ethylene argon -500 500 75 75 300 Implementation Example 1-2 Ethylene argon-500 500 90 60 300 Example 1-3 Ethylene argon-500 500 105 45 300 Example 1-4 Ethylene argon-500 500 120 30 300 Comparative example 1-1 Ethylene argon-500 500 135 15 15 300 Comparative Example 1-2 Ethylene argon -500 500 1500 300 Example 1-5 Ethylene argon -500 500 60 90 300 Example 1-6 Ethylene argon -600 500 90 60 300 Example 1-7 Ethylene argon -700 500 90 60 300 Example 1-8 Ethylene Argon 300 500 90 60 300 Example 1-9 Ethylene Argon -500 500 90 60 500 Example 1-10 Ethylene Helium -500 500 90 60 300 Example 1-11 Ethylene -500 500 90 300 0 Example 1-12 Methane argon -500 500 150 150 300 Example 1-13 Methane argon -500 500 150 60 300 Example 1-14 Acetylene argon -500 500 60 90 300 Example 1-15 Acetylene argon -500 500 90 60 300 Example 1 -16 Ethylene argon -500 700 90 60 300 Example 1-17 Ethylene argon -500 300 90 60 300 Example 1-18 Hydrogen argon 0 700 10 5 10 Example 1-19 Hydrogen argon 0 700 10 3 10 Example 1 -20 hydrogen argon -2 0 700 10 5 10 Comparative Example 1-3 hydrogen argon 0 700 10 0 10

[0057]

[Table 2] Each component and content (atm%) Hardness BOD1 BOD2 CSS FD friction FD durability sample Carbon hydrogen Nitrogen Noble gas GPa (min) (min) (× 1000) (gf) (hour) Examples 1-1 62.0 29.5 7.4 1.1 32.7>300>300> 10 0.4> 300 Example 1-2 66.6 29.2 3.3 0.9 36.9> 300 263> 10 0.4> 300 Example 1-3 64.9 31.7 2.6 0.8 37.0> 300 243> 10 0.6> 300 Example 1-4 65.9 32.7 0.7 0.7 36.5> 300 5> 10 0.8> 300 Comparative Example 1-1 66.4 33.0 0 0.5 38.7> 300 2 7.8 1.2 190 Comparative Example 1-2 60.6 39.0 0 0.4 40.8 28-1.7 1.5 259 Example 1-5 60.9 28.0 9.6 1.5 28.1> 300 261 0.1 0.5 16 Example 1-6 67.4 28.4 3.0 1.2 37.1>300>300> 10 0.5> 300 Example 1-7 68.2 27.0 3.3 1.5 39.2 12-O. 9 0.4 98 Example 1-8 59.2 35.2 5.2 0.4 27.6> 300 2 0.5 0.5> 300 Example 1-9 66.5 28.8 3.5 1.2 37.1> 300 221> 10 0.6> 300 Example 1-10 63.8 30.3 4.7 1.2 30.9> 300 >300> 10 0.4> 300 Example 1-11 57.2 37.5 5.3 0 29.4 74-0.4 0.9 3 Example 1-12 60.2 32.5 6.5 0.8 28.2> 300 2 7.5 0.6> 300 Example 1-13 60.6 33.5 5.2 0.7 29.1 > 300 8 9.8 0.6> 300 Example 1 14 66.9 25.1 7.1 0.9 34.2> 300 32 5.4 0.5 261 Example 1-15 68.7 25.7 4.8 0.8 35.3> 300 55> 10 0.6> 300 Example 1-16 66.1 29.6 3.4 0.9 35.4> 300 191> 10 0.5> 300 Example 1-17 65.2 31.9 2.4 0.5 32.4> 300 9 7.9 0.5 290 Example 1-18 57.7 30.2 12.1 O 22.2 241-1.5 0.6 21 Example 1-19 63.7 28.8 7.5 0.4 23.6 164-1.2 0.8 87 Example 1 20 59.1 26.4 13.8 0.7 26.1 56-2.6 0.8 7 Comparative Example 1-3 78.7 20.9 0 0.4 19.8 10-1.9 1.6 20

As can be seen from the above Examples and Comparative Examples, by changing the flow rates of ethylene and nitrogen, the contents of carbon, hydrogen, nitrogen, and a rare gas change, and when the flow rate of nitrogen decreases, the nitrogen in the protective film decreases. And the noble gas content is reduced. As a result, the hardness of the protective film increases, but the sliding characteristics deteriorate. This is because the friction coefficient increases during repeated sliding. On the other hand, if the flow rate of the nitrogen gas is too large, the hardness decreases, and the sliding characteristics deteriorate. It is considered that this is because the protective film is easily worn due to the decrease in hardness. When the substrate bias voltage is increased, the content of the rare gas in the protective film is increased. Conversely, when the substrate bias voltage is reduced, the content of the rare gas is reduced. In these cases, the sliding characteristics deteriorate in both cases. However, it is considered that when the content of the rare gas is high, the internal reaction of the protective film increases, and when the content is low, the hardness decreases. -When the rare gas is changed from argon to helium, the sliding characteristics do not change much, but the hardness decreases. Also, if no rare gas is added, the content of hydrogen and nitrogen in the protective film increases,
Both hardness and sliding characteristics are reduced. It is considered that the organic property of the film is increased. -When methane is used as the hydrocarbon gas, the hydrogen content in the protective film increases, and the hardness and sliding characteristics tend to decrease. Conversely, when acetylene is used, the hydrogen content tends to decrease. -When the high frequency power was changed, the rare gas content slightly changed, and both the hardness and the sliding characteristics were slightly lowered. -The protective film formed by the reactive sputtering method has low hardness and is inferior in durability to a CVD film having the same composition. The protective film produced according to the present invention can achieve both high hardness and a low coefficient of friction, and as a result, excellent running durability can be obtained for both hard disks and floppy disks.

Examples 2-1 to 2-15 and Comparative Example 2-
1-2 (Production of floppy disk) Maximum protrusion roughness on both sides is 2
A thermosetting imide resin (BANI-N manufactured by Maruzen Petrochemical Co., Ltd.)
After B) was applied by dip coating, 12
After firing for an hour, an undercoat film having a thickness of 1.7 μm was formed. Further, an organosilica sol having a particle diameter of 18 nm was applied on the undercoating film by dip coating, and then dried at 250 ° C. for 1 hour to form fine projections on the undercoating film surface. The density of the formed microprojections was 10 / μm ² . Next, the support was placed in a sputtering apparatus with the support sandwiched between holders, and while the support was heated to 200 ° C., a 30 nm Cr—Ti underlayer was formed by DC magnetron sputtering.
m, followed by a Co-Cr-Pt magnetic film of 25 nm.
A film was formed. The base film and the magnetic film were formed on both sides of the support. Further, after the surface of the magnetic film was cleaned by argon glow, a protective film having a thickness of 20 nm was formed thereon by RF plasma CVD under the film forming conditions shown in Table 3. Next, the sample was taken out of the holder, and a solution prepared by dissolving a perfluoropolyether-based lubricant (FOMBLIN Z-DOL manufactured by Ausimont) in a fluorine-based solvent (HFE-7200 manufactured by Sumitomo 3M) on the protective film was subjected to dip coating. To form a lubricating film having a thickness of 1 nm. Then, this sample was punched into a 3.7-type magnetic disk shape and assembled into a shell to produce a floppy disk.

(Fabrication of Magnetic Head) The sliding surface of a tapered flat 2-rail type Al ₂ O ₃ —TrC slider (nano slider) equipped with an MR head using an MR element as a magnetic recording signal reproducing element is argon. After cleaning with glow, a silicon film was formed as an adhesion layer by DC magnetron sputtering so as to have a thickness of 5 nm.
A carbon protective film was formed thereon by RF plasma CVD under the film forming conditions shown in Table 3 so as to have a thickness of 10 nm. The slider was mounted on a suspension to produce a magnetic head having a trans-perspective head drive mechanism.

(Sample for Hardness Measurement) A sample for hardness measurement was prepared separately from the floppy disk and the magnetic head. This sample was prepared by cleaning a mirror-polished single-crystal silicon substrate with argon glow and then forming a film having a thickness of 0.1 μm under the same conditions as those of the protective films of the floppy disk and the slider. (Evaluation of running durability) Using a combination of the floppy disk and the magnetic head on which the carbon protective film was formed under the film forming conditions shown in Table 3 in Table 4, a running durability test was performed on a track having a radial position of 32 mm from the center of the floppy disk. Was. In the test, a 12-MHz signal was repeatedly recorded and reproduced on both sides of the disk in a one-minute cycle, and the time until the reproduction output decreased to the initial output of -6 dB was evaluated. The test lasted up to 300 hours. The load was 34.3 mN, and the evaluation environment was 23 ° C. and 10% RH.
The results are shown in Table 4.

(Measurement of Hardness of Protective Film) A sample for hardness measurement was subjected to an indentation test using a microhardness meter as described below, and the hardness was determined. Micro hardness measurement instrument: TRIBOSCOPE (HYSIT
Indenter: Diamond indenter Tip angle 90 °, Tip radius of curvature 35-50 nm (Model number:
T1-037) Maximum load: 15 μN Measurement time: 5 seconds Under conditions of 5 seconds, a measurement sample was cut out into a 1 cm square, affixed on a metal plate with a double-sided adhesive tape, and the metal plate on which the measurement sample was mounted was mounted on a measurement device and the maximum. Apply a load and set the load to 0
Operation, and the amount of penetration at this time is measured by an atomic force microscope (Digital Instruments N
(AnoScopeII), and the hardness was defined as a value P / A obtained by dividing the maximum load P by the projected area A of the indenter contact portion.

(Chemical Composition of Protective Film) The C, H, N, and rare gas compositions of the hardness measurement samples were examined by Rutherford backscattering method using an X-ray photoelectron spectrometer (ESCA XPS), and the results were tabulated. 3 is shown.

[0064]

[Table 3] Sample gas flow rate (ccm) Substrate input content (atm%) Hardness C ₂ H ₄ nitrogen Alcohol bias Electric power carbon hydrogen nitrogen rare gas (GPa) A 60 90 300 -500V 500W 60.9 28.0 9.6 1.5 28.1 B 75 75 300 -500V 500W 62.0 29.5 7.4 1.1 32.7 C 90 60 300 -500V 500W 66.6 29.2 3.3 0.9 36.9 O 90 60 300 -300V 500W 59.2 35.2 5.2 0.4 27.6 E 105 45 300 -500V 500W 64.9 31.7 2.6 0.8 37.0 F 120 30 300- 500V 500W 65.9 32.7 0.7 0.7 36.5 G 135 15 300 -500V 500W 66.4 33.0 0 0.5 38.7 H 150 1 300 -500V 500W 60.6 39.0 0 0.4 40.8 I 150 0 300 -300V 500W 57.4 42.3 0 0.3 21.5 J 150 0 300 -200V 500W 40.3 59.7 0 0.0 8.9 K Without carbon protective film

[0065]

Table 4 Sample Floppy disk Type of carbon protective film for running durability time of magnetic head Type of carbon protective film (h) Example 2-1 AH248 Example 2-2 BH> 300 Example 2-3C H> 300 Example 2-4 CH> 300 Example 2-5 CG 212 Example 2-6 CI 255 Example 2-7 C J38 Example 2-8 DH> 300 Example 2-9 EH> 300 Example 2-10 FH> 300 Example 2-11 GH289 Example 2-12 HH98 Example 2-13 HC59 Example 2-14 IH98 Example 2-15 JH44 Comparative Example 2-1 CK12 Comparative Example 2-2 KH0 Comparative Example 2-3 KK0

[0066]

As described above, the floppy disk and the magnetic head provided with the carbon protective film have a recording method using a floppy disk in which the carbon protective film is not provided on either the floppy disk or the magnetic head. In comparison, it can be seen that the running durability is significantly inferior. Further, the hardness of the carbon protective film of the magnetic head is 30 GPa.
And the hardness of the protective film of the floppy disk is 20 to 4
It can be seen that, at 0 GPa, the floppy disk recording method in which the hardness of the carbon protective film of the magnetic head is larger than the hardness of the carbon protective film of the floppy disk has a particularly large effect of improving durability. It can be seen that durability is improved by providing the magnetic head with a carbon protective film centered on carbon and hydrogen and the floppy disk with a carbon protective film centered on carbon, hydrogen and nitrogen. Further, since the carbon protective film is provided on both the floppy disk and the magnetic head, sufficient practical reliability can be ensured even for a high-density floppy disk having a magnetic layer formed of a metal thin film. .

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a CVD apparatus using high-frequency plasma.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Metal thin film, 2 ... Support, 3-roll, 4 ... Pass roller, 5 ... Bias power supply, 6 ... Raw material gas, 7 ... High frequency power supply, 8 ... Film forming roll, 9 ... Carbon protective film, 10 ... Winding roll

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5D006 AA02 AA05 DA02 EA03 FA02 FA05 5D111 BB28 BB37 BB48 FF01 FF44 5D112 AA05 AA07 AA11 AA24 BC05 BC08 FA04 FA10 FB09 FB26

Claims (21)

[Claims] 1. A magnetic disk having a structure in which a magnetic film, a protective film and a lubricating film are laminated on at least one surface of a flexible support, wherein the protective film contains at least carbon, hydrogen and nitrogen. Magnetic disk. 2. A magnetic disk having a structure in which a magnetic layer, a protective film, and a lubricating film are laminated on at least one surface of a flexible support or a rigid support, wherein the protective film is made of at least carbon,
A magnetic disk containing hydrogen, nitrogen and a rare gas element. 3. The protective film has a nitrogen content of 0.5 to 8.0 a.
3. The magnetic disk according to claim 1, wherein the magnetic disk is tm%. 4. The protective film has a hydrogen content of 25 to 35 atm.
%. 3. The magnetic disk according to claim 1, wherein 5. The protective film having a carbon content of 60 to 70 atm.
%. 3. The magnetic disk according to claim 1, wherein 6. The protective film has a rare gas element content of 0.5 to 0.5.
3. The magnetic disk according to claim 2, wherein the content is 1.2 atm%. 7. A method of manufacturing a magnetic disk, comprising: forming a magnetic film on at least one surface of a flexible support or a rigid support; and applying a hydrocarbon to the magnetic film while applying a negative bias to the magnetic film. A method for manufacturing a magnetic disk, comprising forming a protective film on a magnetic film surface by a plasma CVD method using a mixed gas of nitrogen and a rare gas element as a raw material. 8. The method according to claim 7, wherein the magnetic film is formed by a sputtering method. 9. A magnetic recording system using a floppy disk, wherein a magnetic recording medium is a floppy disk in which a ferromagnetic metal thin film and a carbon protective film are laminated on at least one of a flexible support and a head or slider surface is provided. A magnetic recording system using a floppy disk, characterized in that a magnetic signal is recorded and reproduced by a floppy disk device provided with a carbon protective film. 10. The magnetic recording system using a floppy disk according to claim 9, wherein the hardness of the carbon protective film on the floppy disk is lower than the hardness of the carbon protective film on the surface of the head or the slider. 11. The micro-hardness of the carbon protective film of the floppy disk is in the range of 20 GPa to 40 GPa, and the micro-hardness of the carbon protective film on the surface of the head or the slider is 30.
10. The magnetic recording method using a floppy disk according to claim 9, wherein the hardness is not less than GPa and the hardness of the carbon protective film of the floppy disk is lower than the hardness of the carbon protective film on the surface of the head or the slider. 12. A magnetic recording system using a floppy disk, wherein at least one of the flexible supports has a ferromagnetic metal thin film, and at least carbon,
A floppy disk characterized by using a floppy disk laminated with a carbon protective film containing hydrogen and nitrogen as a magnetic recording medium and recording / reproducing a magnetic signal with a floppy disk device having a carbon protective film on a head or a slider surface. A magnetic recording method using a disk. 13. The carbon protective film of the floppy disk has a hydrogen content of 25 to 35 atm% and a nitrogen content of 0.5 to 35 atm%.
13. The magnetic recording system using a floppy disk according to claim 12, wherein the amount is 8.0 atm%. 14. The magnetic recording system using a floppy disk according to claim 12, wherein the carbon protective film of the floppy disk contains at least carbon, hydrogen, nitrogen and a rare gas element. 15. The carbon protective film of a floppy disk contains at least carbon, hydrogen, nitrogen and a rare gas element,
The hydrogen content is 25-35 atm%, the nitrogen content is 0.5-8.0 atm%, and the rare gas element content is 0.5-atm.
13. The magnetic recording system using a floppy disk according to claim 12, wherein the amount is 1.2 atm%. 16. The micro hardness of the carbon protective film of the floppy disk is in the range of 20 GPa to 40 GPa, and the micro hardness of the carbon protective film on the surface of the head or the slider is 30 GPa.
13. The magnetic recording system using a floppy disk according to claim 12, wherein the hardness is not less than GPa and the hardness of the carbon protective film of the floppy disk is lower than the hardness of the carbon protective film on the surface of the head or the slider. 17. A magnetic recording system using a floppy disk, wherein at least one of the flexible supports has a ferromagnetic metal thin film, and at least carbon,
A magnetic recording medium is a floppy disk on which a carbon protective film containing hydrogen and nitrogen is laminated, and recording and reproduction of magnetic signals is performed by a floppy disk device having a carbon protective film containing at least carbon and hydrogen on the surface of a head or a slider. A magnetic recording method using a floppy disk characterized by performing. 18. The carbon protective film of the floppy disk has a hydrogen content of 25 to 35 atm% and a nitrogen content of 0.5 to 35 atm%.
18. The magnetic recording method using a floppy disk according to claim 17, wherein the magnetic recording method is 8.0 atm%. 19. The magnetic recording system using a floppy disk according to claim 17, wherein the carbon film of the floppy disk contains at least carbon, hydrogen, nitrogen and a rare gas element. 20. The carbon protective film of the floppy disk contains at least carbon, hydrogen, nitrogen and palladium gas element,
The hydrogen content is 25-35 atm%, the nitrogen content is 0.5-8.0 atm%, and the rare gas element content is 0.5-atm.
18. The magnetic recording method using a floppy disk according to claim 17, wherein the magnetic recording method is 1.2 atm%. 21. The micro hardness of the carbon protective film of the floppy disk is in the range of 20 GPa to 40 GPa, and the micro hardness of the carbon protective film on the surface of the head or the slider is 30 GPa.
18. The magnetic recording system using a floppy disk according to claim 17, wherein the hardness is not less than GPa and the hardness of the carbon protective film of the floppy disk is lower than the hardness of the carbon protective film on the surface of the head or the slider.