JPH1131321A - Magnetic disk as well as magnetic disk device with the same and production of magnetic disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly improve sliding durability by adding a phosphorus based extreme pressure additive to a perfluoropolyether based compd. as a magnetic disk lubricant. SOLUTION: The lubricating film of the magnetic disk sequentially formed with an underlying film, magnetic film, protective film and lubricating film on a nonmagnetic substrate consists of any one of the perfluoropolyether based compds. expressed by formulas I to III (R1 , R2 , R3 , R4 are hydrocarbon chains, X is a bond group) and the quaternary ammonium phosphite salt compd. expressed by formula IV (R5 , R6 , R7 , R8 , R9 , R10 , are hydrocarbon chains). The perfluoropolyether based compd. having the better sliding durability than that of perfluoroalkyl based compds. is used as the base material for the material constituting the lubricating film and the quaternary ammonium phosphite salt compd. is selected for the purpose of intensifying adsorptive power as the phosphorus based extreme pressure additive. As a result, the good sliding reliability may be assured by effectively functioning the extreme pressure additive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can be widely applied to, for example, improvement of durability of a magnetic recording medium, lubrication film of a sliding portion of electronic equipment, or surface modification such as water repellency and oil repellency.

[0002]

2. Description of the Related Art The demand for hard type magnetic disk drives has been steadily expanding in response to the rapid spread of word processors and personal computers. Further, as for the magnetic disk device, the diameter of the disk is reduced, the device is reduced in size and weight, and the recording density is increased, and a large-capacity small machine is mainly used.

On the other hand, the flying height of the head has been reduced with the increase in the recording density of the magnetic disk, and the head is now entering an extremely low flying area of hf 40 nm or less. It is certain that the tendency of the head flying height will decrease further in the future. In the near future, the recording and reproduction will be performed in a perfect contact state (contact) between the head and the disk, and the sliding conditions will become more severe. For this reason,
Lubricating film, protective film for head sliding surface (Air Bearing Surface
Protective film), disk surface shape (texture shape), etc.
The technology relating to the reliability of sliding between the disk and the head is becoming increasingly important among the technologies of the entire magnetic disk device.

In the prior art, contact sliding occurred only when the disk was started and stopped due to the high flying height of the head. However, when the flying height of the head becomes extremely low as in today, the rotation of the disk is increased. Frequent contact sliding between the head and the disk is facilitated. For this reason, the dynamic friction force (Friction) and abrasion (Wear) between the head and the disk are increased, and a disk crash or damage to the head occurs, so that recording and reproduction become impossible.

On the other hand, dynamic friction force (Friction) and wear (Wea
If the lubricating film is made thicker to reduce r), a high maximum static friction force (Stiction, hereinafter abbreviated as adhesion) will be generated at the start of disk startup, making it impossible to start up the disk,
Serious problems such as damage to the head are likely to occur.
In other words, in the future magnetic disk in which the flying height of the head becomes extremely small, it is necessary to reduce both the kinetic friction force (Friction) and the abrasion (Wear) and the adhesion, but it cannot be dealt with by extension of the conventional technology. Is the current situation. Furthermore, in recent magnetic disk devices, there is a tendency to guarantee environmental resistance (0 ° C. to 50 ° C., under low humidity to high humidity) as sliding reliability.

[0006] In recent years, as means for solving the above problems,
As a lubricant for magnetic disks, there has been proposed a method of adding not only a conventional perfluoropolyether compound but also a phosphorus compound (hereinafter abbreviated as a phosphorus extreme pressure agent). For example, JP-A-61-178720, JP-A-61-178719, JP-A-61-178721, JP-A-61-184716, JP-A-61-184724, and JP-A-61-184724. JP-A-62-103824, JP-A-62-103827, JP-A-62-157319, JP-A-62-236120, JP-A-62-236129, JP-A-62-256218 JP-A-62-266727, JP-A-62-266728, JP-A-62-266729, JP-A-63-153716, JP-A-2-49218,
JP-A-4-271012, JP-A-4-274017, JP-A-4-274018, JP-A-4-274019, JP-A-4-274017
JP-A-4-274020, JP-A-5-73894, JP-A-6-17
No. 6,350, US Pat. No. 5,587,217 and US Pat. No. 5,230,964 apply a phosphorus-based extreme pressure agent alone or in combination with a fluorine-based compound to the surface of a magnetic recording medium.

[0007] Examples of using sulfur-based extreme pressure agents in addition to phosphorus-based extreme pressure agents are disclosed in JP-A-61-178718 and JP-A-61-178718.
JP-A-62-103825, JP-A-61-178722, JP-A-61-184715, and JP-A-61-184715 as examples using halogen-based extreme pressure agents.
JP-A-61-184721, JP-A-61-184722, JP-A-62-103826, and JP-A-62-177719 have been proposed as examples using a boron-based extreme pressure agent. I have.

[0008] The above known examples are all techniques in which the sliding reliability can be improved to some extent by adding an extreme pressure agent.

[0009]

When a sufficient oil film cannot be formed on the friction surface by the oil lubrication system (under boundary lubrication),
The technique of adding a compound containing an element such as phosphorus, sulfur, or chlorine to oil for the purpose of preventing seizure or reducing abrasion is a technique known to those skilled in the art. Is called an extreme pressure agent. The extreme pressure agent reacts with the friction surface due to frictional heat or the like, forms a boundary lubricating film, and has a function of preventing seizure and wear.

The above-mentioned known example utilizes such an effect of the extreme pressure agent. In particular, a boundary lubricating film is formed on the head side by friction to reduce dynamic friction and wear between the head and the disk. . As mentioned earlier, magnetic disks generally use a combination of a perfluoropolyether compound and a phosphorus-based extreme pressure agent. At low temperatures, the perfluoropolyether compound is mainly used as a lubricant. It is considered that a phosphorus-based extreme pressure agent works effectively as a lubricant at high temperatures (Japanese Patent Laid-Open No. 6-176350, US Pat. No. 5,587,2).
17, USP 5,230,964).

However, in order to sufficiently bring out the effects of the extreme pressure agent, several technical problems must be solved.
For example, in a method in which a perfluoropolyether compound and a phosphorus-based extreme pressure agent are mixed and applied to a magnetic disk, the perfluoropolyether-based compound and the phosphorus-based extreme pressure agent are generally uniformly dispersed and do not adhere to the disk surface. The phosphorus-based extreme pressure agents gather and are scattered in a sea-island shape.

This is because the perfluoropolyether compound exhibits strong oil repellency to the phosphorus-based extreme pressure agent, which not only does not provide a stable effect of the phosphorus-based extreme pressure agent but also results in a phosphorus-based extreme pressure agent. The pressure agent may excessively transfer to the head side to cause head dirt and strong adhesion. None of the known examples describe a method for producing a lubricating film in which an extreme pressure agent and a perfluoropolyether compound are uniformly dispersed,
It is necessary to devise a new film forming method capable of uniformly dispersing the perfluoropolyether compound and the phosphorus extreme pressure agent.

[0013] The effect of the extreme pressure agent is also strongly affected by the ease of adsorption to the sliding surface. Recent magnetic heads have a carbon protective film formed on a sliding surface. In the case of a head without a carbon protective film, the sliding surface is made of Al ₂
Since it is O ₃ —TiC, the phosphorus-based extreme pressure agent is Al ₂ O ₃ —T
Although it is easy to adsorb to the metal surface of iC and can form an effective boundary lubrication film, in the head on which the sputtered carbon protective film is formed, the phosphorus-based extreme pressure agent hardly adheres to the sliding surface, and the effect of the phosphorus-based extreme pressure agent is reduced. Cannot be fully utilized. That is, it is necessary to increase the adsorption power of the phosphorus-based extreme pressure agent itself to the head on which the carbon protective film is formed.

To solve such problems, for example, Japanese Patent Application Laid-Open No. 61-178719 proposes a method using a phosphoric acid ester amine salt-based extreme pressure agent capable of obtaining a strong adsorptive power. However, JP-A-61-178720, JP-A-61-178721, JP-A-61-184716, JP-A-61-184724, and JP-A-61-184724, including JP-A-61-178719. JP-A-62-103824, JP-A-62-103827, JP-A-62-157319, JP-A-62-236120, JP-A-62-236129, JP-A-62-256218 JP-A-62-266727, JP-A-62-266728, JP-A-62-266729, JP-A-63-153716, JP-A-2-49218,
JP-A-4-271012, JP-A-4-274017, JP-A-4-274018, JP-A-4-274019, JP-A-4-27401
JP-A-274020 and JP-A-5-73894 use a perfluoroalkyl-based compound as a fluorine-based compound as a base material of a lubricating film, and use a perfluoropolyether-based compound. Bulletin, USP5,587,217, USP
It is considered that sliding durability is inferior to 5,230,964.

In particular, the use of a perfluoropolyether compound in a magnetic disk to ensure sliding durability is a well-known fact among those skilled in the art. That is, it is difficult to form a lubricating film in which the extreme pressure agent and the lubricant serving as the base material are uniformly dispersed by the method proposed in the above-mentioned known example, and a method of fully utilizing the effect of the extreme pressure agent There is no current situation.

The present invention solves the above-mentioned problems, proposes a method capable of ensuring good sliding reliability by effectively using an extreme pressure agent, and a high performance magnetic disk and a magnetic disk to which this method is applied. A disk device is provided.

[0017]

Means for Solving the Problems As a means for solving the above-mentioned problems, as a material for forming a lubricating film, a perfluoropolyether-based compound having better sliding durability than a perfluoroalkyl-based compound is used as a base material. A quaternary ammonium phosphite salt compound was selected as the system extreme pressure agent for the purpose of enhancing the adsorptive power. This quaternary ammonium phosphite salt compound is superior in heat resistance to the phosphate amine salt type extreme pressure agent disclosed in the above-mentioned JP-A-61-178719.

Further, in order to obtain a lubricating film in which the perfluoropolyether compound and the phosphorus-based extreme pressure agent are uniformly dispersed,
A new method of rubbing with a tape made of polyester after applying each lubricant has been devised. Specifically, the following magnetic disk, magnetic disk manufacturing method, and magnetic disk device are provided.

The first means is a magnetic disk having a base film, a magnetic film, a protective film, and a lubricating film formed in this order on a non-magnetic substrate, wherein the lubricating film is represented by the general formulas [1] to [3]. And a quaternary ammonium phosphite salt compound represented by the above general formula [4], and a magnetic disk drive equipped with the same. .

The second means is a magnetic disk device having a magnetic disk formed by sequentially forming a base film, a magnetic film, a protective film, and a lubricating film on a non-magnetic substrate and a magnetic head for recording / reproducing. The lubricating film has the general formula [1]-
The magnetic head during recording / reproduction, comprising one of the perfluoropolyether compound represented by [3] and a quaternary ammonium phosphite salt compound represented by the general formula [4]; 50n gap with disk surface
m or less. Third
Means for mounting a magnetic disk in which a base film, a magnetic film, a protective film, and a lubricating film are sequentially formed on a non-magnetic substrate, and a magnetic disk device equipped with a magnetic head for recording and reproduction; It comprises any one of the perfluoropolyether compounds represented by the general formulas [1] to [3] and the quaternary ammonium phosphite salt compound represented by the general formula [4]. A gap between the magnetic head and the surface of the magnetic disk is 50 nm or less, a maximum static friction coefficient generated between the magnetic head and the magnetic disk is 1.5 or less, and a dynamic friction coefficient is 1.0 or less. Magnetic disk device.

Fourth means is to provide a magnetic disk having a base film, a magnetic film, a protective film, and a lubricating film formed on a non-magnetic substrate in order, when the magnetic disk starts rotating and stops rotating.
_Ra 10 where the magnetic head slider is located during rotation stop
A region having a roughness of not less than nm exists on the inner peripheral portion of the surface of the protective film, and from the region on the outer peripheral side, the roughness at which the magnetic head slider is located during rotation of the magnetic disk is _Ra 3 nm. The following regions are present, and the lubricating film is any one of the perfluoropolyether compounds represented by the general formulas [1] to [3] and the lubricating film represented by the general formula [4]. A magnetic disk drive comprising a quaternary ammonium phosphite salt compound, wherein a maximum static friction coefficient generated between the magnetic head and the magnetic disk is 1.5 or less and a dynamic friction coefficient is 1.0 or less.

Fifth means is to form the lubricating film according to any one of claims 1, 2, 3, and 4 on a magnetic disk surface formed by any one of dip coating, spin coating, and spray coating.
The magnetic disk is rubbed by rotating the magnetic disk at a constant rotational speed with a tape made of polyamide or polyester pressed with a constant load, and further, the tape is wound in one direction during rotation of the magnetic disk, and the magnetic disk and the magnetic disk are rotated. A method for manufacturing a magnetic disk, wherein a contact point of a tape also moves in a radial direction.

A sixth means is the magnetic disk according to any one of claims 1, 2, 3, and 4, wherein the diameter of the magnetic disk is 88.9 mm or less, and a magnetic disk device provided with the magnetic disk.

The lubricating film made of the perfluoropolyether compound and the phosphorus-based extreme pressure agent devised in the present invention is a quaternary which is easily adsorbed on the sliding surface by the phosphorus-based extreme pressure agent and has excellent thermal stability. Using ammonium phosphite salt compound,
Further, in order to uniformly disperse the perfluoropolyether-based compound and the phosphorus-based extreme pressure agent, a lubricating film was formed by a novel method of rubbing with a polyester tape. As a result, in a magnetic disk device in which the head flying height is reduced,
The dynamic frictional force and abrasion generated by the contact sliding of the magnetic head and the magnetic disk can be reduced, and a magnetic disk and a magnetic disk device with high sliding reliability can be obtained.

[0025]

[Embodiment 1] NiP underlayer 10 μm, Cr interlayer 0.5 on a 3.5-inch aluminum alloy substrate whose surface is mirror-polished.
μm, Co-Cr-Pt 60 nm, carbon protective film 2
A sputtered magnetic disk on which 0 nm was sequentially formed was prepared. Next, Teflon particles having a diameter of 0.5 μm were electrostatically applied, the entire surface was etched by 10 nm with oxygen, and the Teflon particles were removed by washing with water. As a result, cylindrical projections having a diameter of 0.5 μm are uniformly formed on the surface of the sputtered magnetic disk. Next, a perfluoropolyether compound (a) represented by the following structural formula [5]

[0026]

Embedded image

And a quaternary ammonium phosphite salt compound (b) represented by the following structural formula [6]:

[0028]

Embedded image

Fluorine-based solvent (HFE-, manufactured by Sumitomo 3M)
7100) to prepare a solution (1). The concentration of the perfluoropolyether compound (a) is 0.1 wt.
%, The concentration of the quaternary ammonium phosphite salt compound (b) is 0.01% by weight. This solution (1)
Was applied by a dipping method and dried sufficiently. The conditions for dip coating are as follows.

Infiltration speed into solution: 10 mm / s Residence time in solution: 180 s Pulling speed from solution: 1.0 mm / s The lubricating film thickness is about 1.5 nm. Next, the disk coated with the above-mentioned lubricant was put in a width of 25 mm and a thickness of 0.5 mm.
Was polished with a polyester tape (manufactured by Toray Industries, Inc.). FIG. 1 shows an outline of the apparatus used.

The polyester tape is pressed against the disk surface by a constant air pressure, and moves in the radial direction as the disk rotates. The pressing load in this embodiment is about 20 gf. At this time, since the tape is also wound in one direction, the disk is always rubbed by a new tape surface.
In this embodiment, the disk surface was reciprocated two times at a disk rotation speed of 5400 rpm and a tape pressing load of 20 gf. In the apparatus shown in FIG. 1, tapes having different materials and widths can be used, and the pressing load can be selected in the range of 0 gf to 50 gf. Further, the tape can be pressed not only by air pressure but also by a roller by attaching a roller to the tape pressing portion.

A sliding test was performed on the sputtered magnetic disk manufactured in this manner under the following conditions. FIG. 2 shows an outline of the measuring apparatus.

The magnetic disk 7 to be measured is mounted on a spindle 8 directly connected to a motor at the lower part of the apparatus, and is fixed by a disk holder 9. The head slider 12 is of an in-line type (20T made of Al ₂ O ₃ —TiC) whose rail surface is in contact with the rotation direction of the disk in the forward direction, and is fixed to an arm 13 connected to the load cell 10. The stage 11 fixing the load cell 10 is
It can move in the radial direction, and can be evaluated on each track. The frictional force generated between the head slider 12 and the magnetic disk 7 by rotating the motor is measured by a load cell.

In this embodiment, in order to evaluate the sliding characteristics during contact sliding, the disk was rotated at such a speed that the head did not float, and the head was slid in contact with the disk. Head uses 2 rail nano slider Al ₂ O ₃ -TiC manufactured, disk rotation speed 150 rpm, a pressing load 5g of the head. The test is conducted up to 60k times, during which the number of sliding times is 0.15k times and 1.5k times.
Times, 4.5k times, 7.5k times, 10.5k times, 13.5k
Times, 16.5k times, 19.5k times, 22.5k times, 30k
Times, 37.5k times, 45k times, 52.5k times, 60k times, stop the disk and contact the head for 2 seconds, then 1
The maximum value of the maximum static friction force and the maximum value of the dynamic friction force when rotating at 0 rpm were measured. In addition, the number of slides at which the disk crashed was measured. A disk crash is a condition in which the carbon protective film, which is the foundation of the lubricating film, has been completely worn and the magnetic film has been exposed.If a crash occurs, a sliding mark that can be visually confirmed is generated. The measurement was taken and the experiment was stopped. FIG. 3 shows the above evaluation results.

In this embodiment, the perfluoropolyether compound (a) used in this embodiment was applied to the same magnetic disk surface.
In comparison with Comparative Example 1 in which only
The disk crash did not occur up to 60k times, whereas in Comparative Example 1, the disk crashed at 10.5k times. In addition, comparing the maximum static friction force and the dynamic friction force, the value of the present example in which the quaternary ammonium phosphite salt compound (b) was added was lower than that of the present example. In Comparative Example 2 in which the same perfluoropolyether compound (a) and quaternary ammonium phosphite salt compound (b) as in this example were applied and polishing was not performed with a polyester tape, disk crash did not occur. The maximum static frictional force and the dynamic frictional force are higher than those of the present embodiment, and particularly, the maximum static frictional force shows a high value, and strong adhesion occurs.

Example 2 The same sputtered magnetic disk as in Example 1 was prepared. Next, a perfluoropolyether compound (c) represented by the following structural formula [7]:

[0037]

Embedded image F (CF ₂ CF ₂ CF ₂ —O) _n C ₂ F ₄ —CH ₂ —OH (7) Quaternary ammonium phosphite salt compound (d) represented by the following structural formula [8]

[0038]

Embedded image

Was dissolved in the same fluorine-based solvent at the same concentration as in Example 1 and applied under the same conditions. The lubricating film thickness is about 1.7 nm. Next, as in Example 1, polishing was performed with a polyester tape.

The sliding characteristics of the lubricating film produced in this example were measured in the same manner as in Example 1. Table 1 shows the results. Compared to Comparative Example 3 in which only the perfluoropolyether compound (c) was applied, the results of this example did not cause a disk crash up to 60k times, whereas Comparative Example 3 caused a disk crash at 7.5k times. In addition, the maximum static friction force and the dynamic friction force are lower in the present example in which the quaternary ammonium phosphite salt compound (d) is added.

Example 3 The same magnetic disk as in Example 1 was mounted on a 3.5-inch magnetic disk device. FIG. 4 shows a schematic diagram of the apparatus.

A 3.5-inch magnetic disk device of the same type (Comparative Example 4), on which the magnetic disk device and the magnetic disk manufactured in Comparative Example 1 were mounted, was placed in a thermostat, and a CSS (contact / contact) with a seek operation was performed. Start / Stop) test. In the thermostat, the temperature was raised from 0 ° C to 55 ° C at a rate of 1 ° C / sec.

[0043]

[Outside 1]

The cycle of cooling was repeated and the test was carried out continuously for 1000 hours. After the test, the magnetic disk was taken out of the apparatus and the disk surface was observed. As a result, in the magnetic disk manufactured in Example 1, no sliding marks were observed on the disk surface, and no abrasion powder or dirt was attached to the sliding surface of the magnetic head. On the other hand, in the magnetic disk manufactured in Comparative Example 1, abrasion occurred on the entire surface of the disk, and deep scratch marks were observed in a part thereof. Further, abrasion powder and a lubricant adhered to the sliding surface of the magnetic head.

Comparative Example 1 The same sputtered magnetic disk as in Example 1 was prepared. Next, only the perfluoropolyether compound (a) of the structural formula [5] used in Example 1 was applied by a dipping method in the same manner as in Example 1, dried sufficiently, and polished with a polyester tape. . The thickness of the lubricating film is 1.51 nm. A sliding test was performed on the disk manufactured in the same manner as in Example 1.
FIG. 3 shows the results.

Comparative Example 2 The same sputtered magnetic disk as in Example 1 was prepared. Next, the perfluoropolyether compound (a) of the structural formula [5] and the quaternary ammonium phosphite salt compound (d) of the structural formula [6] used in Example 1 were the same as in Example 1. A solution in which the same concentration was dissolved in a fluorinated solvent was prepared and applied under the same conditions. In addition,
In this comparative example, polishing with a polyester tape was not performed. A sliding test was performed on the disk manufactured in the same manner as in Example 1. FIG. 3 shows the results.

Comparative Example 3 The same sputtered magnetic disk as in Example 1 was prepared. Next, a solution was prepared by dissolving only the perfluoropolyether compound (c) of the structural formula [7] used in Example 2 in the same fluorine-based solvent as in Example 1 at the same concentration, and was applied under the same conditions. . The lubrication film thickness is about 1.7n
m. Next, as in Example 1, polishing was performed with a polyester tape. A sliding test was performed on the disk manufactured in the same manner as in Example 1. FIG. 3 shows the results.

Comparative Example 4 A 3.5-inch magnetic disk drive of the same type, on which the magnetic disk manufactured in Comparative Example 1 was mounted, was placed in the same thermostat as in Example 3, and a CSS (contact / contact) with a seek operation was performed. Start / Stop) test. As in Example 3, after the test was completed, the magnetic disk was taken out of the device and the disk surface was observed. As described in Example 3, in the magnetic disk manufactured in Comparative Example 1, abrasion occurred on the entire surface of the disk, and deep scratch marks were observed in some parts. Further, abrasion powder and a lubricant adhered to the sliding surface of the magnetic head.

[0049]

The sliding durability can be greatly improved by adding a phosphorus-based extreme pressure agent to a perfluoropolyether compound as a lubricant for a magnetic disk. In particular, in the present invention, the use of a quaternary ammonium phosphite salt compound having a strong adsorption power and excellent heat resistance as a phosphorus-based extreme pressure agent allows the phosphorus-based extreme pressure agent to function more effectively than conventional techniques. I do. Further, by polishing with a polyester tape after applying the lubricant, a lubricating film in which the perfluoropolyether-based compound and the phosphorus-based extreme pressure agent are uniformly dispersed can be obtained, and adhesion can be prevented. According to the present invention, it is possible to provide a highly reliable magnetic disk and a magnetic disk device having both contact sliding durability and low adhesiveness.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a polishing apparatus using a polyester film tape, which was implemented in Examples 1 and 2 and Comparative Examples 1 and 3.

FIG. 2 is a schematic diagram of an apparatus for evaluating sliding characteristics.

FIG. 3 is a graph showing the results of Examples 1 and 2 and Comparative Examples 1, 2, and 3 measured by the evaluation device of FIG.

FIG. 4 is a schematic diagram of a magnetic disk drive of Example 3 and Comparative Example 4.

[Explanation of symbols]

1: magnetic disk, 2: polyester film tape,
3 ... Air tube for pressing tape, 4 ... Guide roller, 5 ... Spindle, 6 ... Disk press, 7 ... Low cell, 8 ... Stage, 9 ... Head slider, 10 ... Arm, 11 ... Gimbal, 12 ... Mechanical unit, 13 ... Circuit, control unit.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10M 105: 54 137: 08) C10N 30:06 40:18 50:10 (72) Inventor Yutaka Ito Omikamachi, Okamachi, Hitachi City, Ibaraki Prefecture Hitachi 1-1, Hitachi, Ltd., Hitachi, Ltd. (72) Inventor Miryo Shoji 7-1-1, Omika-cho, Hitachi, Ibaraki Pref., Hitachi Research Laboratory, Hitachi, Ltd.

Claims (6)

[Claims] A non-magnetic substrate, a base film, a magnetic film, a protective film,
In a magnetic disk in which a lubricating film is formed in order, the lubricating film is represented by the following general formulas [1] to [3]. (Where R ₁ , R ₂ , R ₃ , and R ₄ are hydrocarbon chains, and X is a bonding group) and one of perfluoropolyether compounds represented by the following general formula [4]: (Where R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , and R ₁₀ are hydrocarbon chains) and a magnetic disk comprising a quaternary ammonium phosphite salt compound represented by the formula: Magnetic disk drive equipped. 2. An underlayer, a magnetic film, a protective film,
In a magnetic disk device equipped with a magnetic disk in which a lubricating film is formed in order and a magnetic head for recording and reproduction, the lubricating film is a perfluoropolyether-based compound represented by the general formulas [1] to [3]. The magnetic head is composed of one of the compounds and a quaternary ammonium phosphite salt compound represented by the general formula [4], and a gap between the magnetic head and the surface of the magnetic disk during recording / reproduction is 50 nm or less. Characteristic magnetic disk drive. 3. A base film, a magnetic film, a protective film,
In a magnetic disk device equipped with a magnetic disk in which a lubricating film is formed in order and a magnetic head for recording and reproduction, the lubricating film is a perfluoropolyether-based compound represented by the general formulas [1] to [3]. A quaternary ammonium phosphite salt compound represented by the general formula [4], wherein a gap between the magnetic head and the surface of the magnetic disk during recording / reproduction is 50 nm or less; A magnetic disk drive, wherein the maximum static friction coefficient generated between the magnetic head and the magnetic disk is 1.5 or less, and the dynamic friction coefficient is 1.0 or less. 4. An underlayer, a magnetic film, a protective film,
In a magnetic disk in which a lubricating film is formed in order, a region having a roughness of _Ra 10 nm or more where the magnetic head slider is located when the magnetic disk starts rotating, stops rotating, and stops rotating is formed on the surface of the protective film. Exists on the inner circumference,
On the outer peripheral side from the area, there is an area where the magnetic head slider is located during the rotation of the magnetic disk and the roughness is _Ra 3 nm or less.
It comprises any one of the perfluoropolyether compounds represented by [3] and a quaternary ammonium phosphite salt compound represented by the general formula [4], and is provided between the magnetic head and the magnetic disk. A magnetic disk drive wherein the maximum static friction coefficient generated is 1.5 or less and the dynamic friction coefficient is 1.0 or less. 5. A magnetic disk according to claim 1, wherein said magnetic disk has a diameter of 88.9 mm or less, and a magnetic disk device equipped with said magnetic disk. 6. A method according to claim 1, wherein the lubricating film is formed by any one of dip coating, spin coating, and spray coating. The magnetic disk is rubbed by rotating the magnetic disk at a constant rotational speed with the tape to be wound, and further, the tape is wound in one direction during the rotation of the magnetic disk, and the contact point between the magnetic disk and the tape also moves in the radial direction. A method for manufacturing a magnetic disk.