JPH11203777A - Magnetic disk drive - Google Patents

Abstract

(57) Abstract: The present invention relates to lubricating grease for a spindle bearing and an actuator bearing used in a magnetic disk drive, and a magnetic disk drive using these greases. It is an object of the present invention to provide a highly reliable magnetic disk device in which stiction (adhesion) between a head slider and a disk is prevented by greatly reducing a scattered component from grease. The lubricating grease for a spindle bearing and an actuator bearing of the present invention has an oil separation of 0 to 0.
0.5wt%, mixing consistency 220-295, dropping degree 19
It is characterized by a temperature of 0 ° C. or more and an evaporation amount of 0.2 wt% or less. Thus, a highly reliable magnetic disk drive can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can be widely applied to the improvement of sliding reliability of a magnetic recording device and a lubricant for a sliding portion of electronic equipment.

[0002]

2. Description of the Related Art Demand for hard type magnetic disk drives has been steadily expanding with the rapid spread of word processors and personal computers. In the magnetic disk device, the diameter of the disk is reduced, the size and weight of the device are reduced, and the recording density is rapidly increased. A large-capacity small machine is mainly used. As the recording density of the magnetic disk has been increased, the flying height of the head has been reduced, and it has already entered the 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 head and the disk will be recorded and reproduced in a perfect contact state (contact), and the sliding condition between the head and the disk will be further improved. Become severe. For this reason, 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.

[0003] The sliding characteristics between the head and the disk include not only the mechanical characteristics of the lubricating film and the protective film on the disk surface, the surface shape of the disk surface, but also contamination and surrounding atmosphere, that is, the so-called external Is also affected by various factors. In particular, in the current magnetic disk drive in which the head flying height has been reduced to 50 nm or less, a sliding failure due to external factors is likely to occur, and in the future magnetic disk device in which the flying height is further reduced, a more serious sliding failure will occur. It could be the main factor that causes it.

[0004] Contamination in a magnetic disk drive that seriously impairs the reliability of sliding between a head and a disk may be introduced from the outside when the device is assembled, or may be generated from various components used in the device. Countermeasures against contamination introduced from the outside during equipment assembly are relatively easy by improving the working environment (cleanness etc.)
For contamination generated from components, it is necessary to change the components themselves. Examples of known contaminants generated from these components include siloxane generated from silicone rubber and the like, a fungicide, organotin generated from paint, and scattered grease generated from grease in bearings of spindles and actuators. In particular, with regard to the scattered grease, since the temperature inside the device tends to rise due to the speeding up and miniaturization of the device, the amount of scattered grease is increased, and the scattered material adheres to the disk or the head and high stiction (adhesion) Is easy to cause. For this reason, in order to ensure the reliability of the magnetic disk drive in the future, it is necessary to take some measures to prevent the flying grease.

To solve the above problem, as a method of removing contamination entering from the outside, Japanese Patent Application Laid-Open No. Hei 7-211055 proposes a magnetic disk device having a built-in filter capable of removing both chemical contaminants and fine particles. Have been.
However, as a countermeasure against contamination generated inside the apparatus such as scattering grease, a drastic countermeasure such as eliminating generation from components is necessary.

[0006]

As described above, in order to prevent contamination occurring inside the apparatus, it is necessary to prevent the occurrence of contamination from components. With regard to splash grease, grease used for bearings of spindles and actuators (miniature bearings) is selected mainly for the purpose of ensuring the lubrication of the bearings, so that a small amount of scattered matter that may be a problem in magnetic disk drives etc. At present, sufficient consideration has not been given to them. Therefore, it is necessary to develop a grease with low scattering while ensuring sufficient lubrication of the bearing. Grease is basically composed of a base oil, a thickener, and an additive (antioxidant). The components of the splash grease are those in which the low molecular weight components of these base oils, thickeners and additives are splashed. For example, a method of removing a low molecular weight component of the base oil or increasing the molecular weight of the base oil is conceivable. However, increasing the molecular weight increases the viscosity of the base oil and increases the penetration of the grease. The admixing penetration is a mechanical property value that affects the followability of the grease to the lubricating portion, and an optimal admixing penetration is set for the structure and operating conditions of the bearing. For this reason, the technique of increasing the molecular weight of the base oil or the like may reduce the followability of the grease to the lubricating portion due to an increase in the penetration, and may impair the lubricity of the bearing. Therefore,
It is necessary to develop and select low-dispersion grease while maintaining the mechanical consistency value of the penetration consistency. At present, there is no effective means for solving such problems.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an object of the present invention is to propose a technique for an effective grease which is hardly scattered in a magnetic disk drive and to provide a high-performance magnetic disk drive to which this technique is applied.

[0008]

As a means for solving the above-mentioned problems, a novel method of combining a base oil, a thickener, and an additive which can sufficiently secure the lubricating performance of a bearing with a low evaporation amount and a low oil separation. Was invented. Specifically, the following magnetic disk device is used.

The first means is 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 head slider for writing or reading data on or from the magnetic disk. A carrier for mounting the magnetic head slider near the surface of the magnetic disk, an actuator for moving the carrier and the magnetic head slider on the surface of the magnetic disk, and the magnetic disk for rotating the magnetic disk In a magnetic disk drive in which a spindle motor connected to a spindle motor is accommodated in a container, lubricating grease used for the actuator and the bearing portion of the spindle motor has an oil separation of 0 to 0.5 wt% and a mixing consistency of 2
20-295, drop point 190 ℃ or more, evaporation amount 0.2wt%
A magnetic disk drive characterized by the following.

The second means is 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 head slider for writing or reading data on the magnetic disk. A carrier for mounting the magnetic head slider near the surface of the magnetic disk; an actuator for moving the carrier and the magnetic head slider on the surface of the magnetic disk; and a magnetic device for rotating the magnetic disk. In a magnetic disk drive in which a spindle motor connected to a disk is housed in a container, an additive of lubricating grease used for the actuator and a bearing portion of the spindle motor is at least one of an amine compound or a phenol compound. The base oil is a polyol ester oil, Ether-based oil, fluorine-based oil, with trimellitic acid ester oils of one or more magnetic disk device, characterized in that the thickener is either a lithium soap, lithium complex soap, a urea compound.

The third means is 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 the magnetic head for writing or reading data to or from the magnetic disk. A slider, a carrier for mounting the magnetic head slider near the surface of the magnetic disk, an actuator for moving the carrier and the magnetic head slider on the surface of the magnetic disk, and a magnetic element for rotating the magnetic disk. In a magnetic disk drive in which a spindle motor connected to a disk is accommodated in a container, lubricating grease used for the actuator and the bearing portion of the spindle motor has an oil separation of 0 to 0.5 wt% and a mixing consistency of 2.
20-295, drop point 190 ℃ or more, evaporation amount 0.2wt%
In the following, the additive is at least one of an amine compound or a phenolic compound, and the base oil is at least one of a polyol ester oil, a phenyl ether oil, a fluorine oil, and a trimellitate oil. A magnetic disk drive characterized in that the agent is any of lithium soap, lithium composite soap and urea compound.

The fourth means is 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, and a magnetic head slider for writing or reading data on or from the magnetic disk. A carrier for mounting the magnetic head slider near the surface of the magnetic disk, an actuator for moving the carrier and the magnetic head slider on the surface of the magnetic disk, and the magnetic disk for rotating the magnetic disk A magnetic disk drive in which a spindle motor connected to the magnetic disk drive is accommodated in a container, wherein the maximum static friction coefficient between the head and the disk at the time of starting the apparatus is 1.2 or less.

Examples of the amine compound as an additive according to the present invention include alkylated diphenylamine, octylated diphenylamine, N, N'-di-2-naphthyl-
p-phenylenediamine, N, N'-diphenyl-p-
Phenylenediamine and the like, and examples of the phenolic compound include triethylene glycol-bis [3- (3-
t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3
-(3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3 − (3,
5-di-tert-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide)
And the like. Further, examples of the polyol ester-based oil as the base oil include neopentyl glycol ester oil, trimethylolpropane oil, pentaerythritol ester oil, dipentaerythritol ester oil, and the like. There are four types of structural formulas,

[0014]

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Examples of phenyl ether oils include:
Hexadecyl 2- (3-phenoxyphenoxy) biphenyl, 3- (3-phenoxyphenoxy) biphenyl,
Dihexadecyl 2- (3-phenoxyphenoxy) biphenyl, 1,3-bis (3-phenoxyphenoxy) benzene, 1- (3-phenoxyphenoxy), 3- (4
-Phenoxyphenoxy) benzene, 1,3-bis (4
-Phenoxyphenoxy) benzene and the like. Examples of the urea compound include aliphatic diurea, alicyclic diurea, aromatic diurea, triurea, and tetraurea. The present invention is not limited to these compounds.

By using the grease of the present invention for a bearing of a spindle and an actuator in a magnetic disk drive, it is possible to prevent the generation of grease scattered substances which adversely affect the sliding between the head and the disk, and to improve the sliding reliability. A high magnetic disk drive can be obtained.

[0017]

(Example 1) 12 g of lithium stearate was added to 50 g of trimellitic acid ester oil (TOTM manufactured by Daihachi Chemical Co., Ltd.) and stirred at 200 ° C.
The mixture was gradually cooled to a temperature of about 80 ° C., cooled at about 80 ° C., and 1 g of octylated diphenylamine (IRGANOX5057 manufactured by Ciba-Geigy Japan) dissolved in 38 g of the trimellitate oil was added. The mixture was stirred and cooled to room temperature with stirring. Next, the mixture was kneaded two or three times with a three-roll mill, and NLGI consistency grade No.
The lithium soap grease of No. 2 was prepared. The degree of oil release of the produced grease was measured according to JIS K2220-5.7 (100 ° C,
24h), and determine the penetration consistency according to JIS K2220-5.
3. The drop point is JIS K2220-5.4.
It was measured with SK2220-5.6B (100 ° C, 22h). As a result, the oil release of the produced grease was 0.05 w
As a result, the mixing consistency was 273, the dropping point was 225 ° C., and the amount of evaporation was 0.07 wt%. The friction test was carried out while heating the grease thus produced in the evaluation apparatus shown in FIG.

The magnetic disk 1 is mounted on a spindle 2 directly connected to a motor at the lower part of the apparatus, and is fixed by a disk holder 3. The head slider 4 is an in-line type (A) in which the rail surface is in contact with the rotating direction of the disk in the forward direction.
l ₂ O ₃ -TiC made are of second rail nano slider) is fixed to the arm 5 with a built-in strain gauge. The arm 5 is directly connected to the motor 6 at the lower part of the apparatus, and is rotatable around the directly connected portion as an axis. However, the operating range of the arm 5 is controlled such that the head slider 4 attached to the arm 5 moves on the surface of the magnetic disk 1 having a radius of 19 mm to 40 mm. That is, the arm 5 corresponds to an actuator of an actual magnetic disk device, and can perform a seek operation and a measurement of a frictional force by being rotated by the motor 6. The apparatus includes a code heater 7 for controlling the temperature of the apparatus from room temperature to 80 ° C. and a bar heater 8 for heating and scattering grease. The magnetic disk 1 has a NiP base film 1 on a 3.5-inch aluminum alloy substrate whose surface is mirror-polished.
0 μm, Cr interlayer 0.5 μm, Co-Cr-Pt60
nm and a carbon protective film of 20 nm are formed in this order, and a uniform cylindrical projection having a diameter of 0.2 μm is formed on the surface of the carbon protective film. Further, a perfluoropolyether compound represented by the following structural formula (Fomblin Z-Dol manufactured by Ausimont Co.) was added to the magnetic disk 1.

[0019]

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The coating is performed with a thickness of about 2.2 nm. The perfluoropolyether compound is applied using a fluorine solvent.
(HFE-7100, manufactured by Sumitomo 3M) was prepared by dissolving it at 0.13 wt% and applied by a dip method.
The conditions for dip coating are as follows.

Infiltration speed into the solution: 10 mm / s Residence time in the solution: 180 s Pulling speed from the solution: 1.0 mm / s In the friction test, the disk rotation speed was 7200 rpm, the head pressing load was 5 g, and the frequency of the seek operation. 36 at 15kHz
It was made to seek continuously for hours. Then stop the disk,
The head was allowed to stand for 6 hours with the head in contact, and the maximum static friction coefficient (Stiction) when the disk was restarted was measured. During the test, 50 mg of the produced grease was applied to the bar heater 8, and the bar heater was heated to 65 ° C. The temperature inside the apparatus was controlled at 65 ° C. by the code heater 7. As a result of the measurement, Comparative Examples 1 and 2 were subjected to the same friction test using grease prepared using a common mineral oil as a base oil.
In this embodiment, the maximum coefficient of static friction is equal to 0.
In contrast, it is 7.6 in Comparative Example 1 and 5.6 in Comparative Example 2. When the disk surface after the test of Comparative Examples 1 and 2 was completed was observed with an optical microscope, a large amount of grease scattered matter was adhered, and a trace of the grease scattered matter adhered by the head slider was confirmed in the seek portion. Was. On the other hand, in the present embodiment, no adhesion of grease scattered matter is recognized. That is, the grease of Comparative Example 1 was easily scattered by the heating of the bar heater, and a large amount of grease scattered matter adhered to the disk surface.
It can be said that n) has occurred.

Example 2 12-hydroxystearic acid 10 in 435 g of alkyl diphenyl ether oil
6.6 g and azelaic acid 23.4 g were added, and the mixture was heated and dissolved at 80 to 90 ° C. with stirring. At this temperature, a mixture of 26.1 g of lithium hydroxide and 52.2 g of hot water was added, and the mixture was subjected to a saponification reaction at 95 to 100 ° C. for 1 hour with stirring. Next, 12 g was heated to about 210 ° C. with stirring and maintained for 5 minutes, and taken in 50 g of a fluorinated oil (Fomblin Z-03 manufactured by Ausimont) represented by the following structural formula.

[0023]

Embedded image

In addition, the temperature was gradually raised to 200 ° C. with stirring, kept for 1 minute, and then cooled while stirring. At about 80 ° C., triethylene glycol-bis [3- (3-t-butyl-5-methyl) was added. -4-Hydroxyphenyl) propionate] (IRGANOX245 manufactured by Ciba-Geigy Japan) dissolved in 38 g of the above-mentioned fluorine-based oil is added,
The mixture was stirred and cooled to room temperature with stirring. Next, the mixture was kneaded 2-3 times with a three-roll mill, and NLGI consistency grade N was used.
o.2 Lithium soap grease was prepared. The degree of oil separation, the degree of mixing penetration, the dropping point, and the amount of evaporation of the produced grease were measured in the same manner as in Example 1. As a result, the oil separation was 0.12 wt%, the penetration was 286, and the dropping point was 231.
° C and the amount of evaporation was 0.05 wt%.

The grease thus produced was subjected to the same friction test as in Example 1 while heating it in the evaluation apparatus shown in FIG. As a result of measurement, the maximum static friction coefficient was 0.74,
Good results were obtained as compared with Comparative Examples 1 and 2.

Example 3 To 25 g of trimellitate oil was added 4.69 g of 4,4'-diphenylmethane diisocyanate, and the mixture was heated and dissolved at 70 to 75 ° C. with stirring.

A mixture of 4.83 g of octylamine dissolved in 25 g of trimellitate oil at 70 to 75 ° C. was added, and the mixture was reacted at 95 to 100 ° C. for 1 hour with stirring. Next, the mixture was heated to about 170 ° C. with stirring, kept for 30 minutes, and then cooled. At about 80 ° C., octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate ( Nippon Ciba Geigy
1 g of IRGANOX 1076) dissolved in 38 g of the above trimellitate oil was added, and the mixture was stirred and cooled to room temperature with stirring. Next, 2-3 roll mill machine
The urea grease of NLGI consistency grade No. 2 was prepared by kneading. The degree of oil separation, the degree of mixing penetration, the dropping point, and the amount of evaporation of the produced grease were measured in the same manner as in Example 1. As a result, the oil separation was 0.06 wt%, the penetration was 272, the dropping point was 221 ° C., and the evaporation was 0.07.
Met.

The grease thus produced was subjected to the same friction test as in Example 1 while heating it in the evaluation apparatus shown in FIG. As a result, the maximum coefficient of static friction was 0.42, and good results were obtained as compared with Comparative Examples 1 and 2.

Example 4 12 g of lithium stearate was added to 50 g of triester oil (REORUB LT3000 manufactured by Ciba-Geigy Japan), and the mixture was stirred for 20 minutes.
The temperature was gradually increased to 0 ° C., kept for 1 minute, and then cooled while stirring. At about 80 ° C., N, N′-di-2-naphthyl-p
-A solution prepared by dissolving 1 g of phenylenediamine (Nocrack White, manufactured by Ouchi Shinko Chemical Co., Ltd.) in 38 g of the triester oil was added, and the mixture was stirred and cooled to room temperature with stirring. Next, the mixture was kneaded 2-3 times with a three-roll mill,
A lithium soap grease of LGI consistency grade No. 2 was prepared. The degree of oil separation, the degree of mixing penetration, the dropping point, and the amount of evaporation of the produced grease were measured in the same manner as in Example 1. As a result, the oil separation was 0.09, and the penetration was 23.
8. The dropping point was 210 ° C. and the evaporation amount was 0.12.

The grease thus produced was subjected to a friction test similar to that of Example 1 while heating the grease in the evaluation apparatus shown in FIG. As a result of measurement, the maximum static friction coefficient was 0.46,
Good results were obtained as compared with Comparative Examples 1 and 2.

Example 5 12 g of lithium stearate was added to 50 g of tetraester oil (REORUB LT3600 manufactured by Ciba Geigy Japan), and the mixture was stirred at 200 ° C.
The temperature was gradually raised to about 80 ° C., and the mixture was cooled while stirring. After about 80 ° C., N, N′-diphenyl-p-phenylenediamine (Nocrack DP, manufactured by Ouchi Shinko Chemical Co., Ltd.) 1
g was dissolved in 38 g of the above tetraester oil, and the mixture was stirred and cooled to room temperature with stirring. Next, the mixture was kneaded two to three times with a three-roll mill to prepare a lithium soap grease of NLGI consistency grade No. 2. The degree of oil separation, the degree of mixing penetration, the dropping point, and the amount of evaporation of the produced grease were measured in the same manner as in Example 1. As a result, the oil separation was 0.11 wt%, and the penetration was 28.
1. The drop point was 215 ° C., and the evaporation amount was 0.15 wt%.

The grease thus produced was subjected to the same friction test as in Example 1 while heating it in the evaluation apparatus shown in FIG. As a result of the measurement, the maximum coefficient of static friction was 0.5, and good results were obtained as compared with Comparative Examples 1 and 2.

Example 6 12 g of lithium stearate was added to 50 g of phenyl ether oil (S-3101 manufactured by Matsumura Petroleum Laboratories), gradually raised to 200 ° C. with stirring, kept for 1 minute, and then removed with stirring. Cool, about 80
At the time of ° C, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide)
A solution prepared by dissolving 1 g of IRGANOX1098 (manufactured by Ciba-Geigy Japan) in 38 g of the above phenyl ether oil was added, and the mixture was stirred and cooled to room temperature with stirring. Next, the mixture was kneaded two to three times with a three-roll mill to prepare a lithium soap grease of NLGI consistency grade No. 2. Example 1
Using the same method as described above, the degree of oil release, the degree of penetration, the dropping point, and the amount of evaporation of the prepared grease were measured. As a result, the oil separation was 0.09, the penetration was 238, the dropping point was 210 ° C,
The evaporation amount was 0.12.

The grease thus produced was subjected to the same friction test as in Example 1 while heating it in the evaluation apparatus shown in FIG. As a result of the measurement, the maximum static friction coefficient was 0.64,
Good results were obtained as compared with Comparative Examples 1 and 2.

(Embodiment 7) Embodiments 1, 2, 3, 4, 5,
Three magnetic disk drives were prepared in which the grease prepared in 6 was filled in the bearing of the actuator section 9 and the bearing of the spindle 2, respectively. FIG. 2 shows a schematic diagram of the magnetic disk drive.

After operating these three magnetic disk units continuously for 1000 hours in an atmosphere of 65 ° C., they were stopped for 30 hours and restarted to confirm the operation of the units. Each bearing of the actuator section 9 was filled with 5 mg of grease, and the bearing of the spindle 2 was filled with 50 mg of grease.

As a result of comparison with two magnetic disk drives of Comparative Example 3 filled with grease produced in Comparative Examples 1 and 2,
In the three magnetic disk devices evaluated in this example, no abnormality was recognized at the time of restart, whereas the magnetic disk device of Comparative Example 3 could not be restarted. As a result of checking the disk in the apparatus of Comparative Example 3, it was found that strong sticking due to grease scatter occurred between the head slider and the disk.

(Comparative Example 1) 8 g of lithium stearate used in Example 3 was added to 70 g of paraffinic mineral oil.
Gradually raise the temperature to 200 ° C. with stirring, hold for 1 minute, and then cool while stirring. At about 80 ° C., 1 g of the octylated diphenylamine used in Example 1 was dissolved in 22 g of the above paraffinic mineral oil. The mixture was added and stirred and cooled to room temperature with stirring. Next, two-roll mill
The mixture was kneaded three times to prepare a lithium soap-based grease of NLGI consistency grade No. 1. The degree of oil separation, the degree of mixing penetration, the dropping point, and the amount of evaporation of the produced grease were measured in the same manner as in Example 1. As a result, the oil separation was 8.2, the penetration was 334, the dropping point was 177 ° C, and the evaporation was 5.3.
wt%. The grease produced in this manner was subjected to a friction test while being heated in the evaluation apparatus shown in FIG. As a result, the maximum static friction coefficient is 7.6.
Met.

Comparative Example 2 Polyalphaolefin Oil 70
8 g of lithium stearate used in Example 1 was added to the mixture, and the temperature was gradually increased to 200 ° C. with stirring, kept for 1 minute, and then cooled while stirring. At about 80 ° C., the octyl used in Example 1 was cooled. A solution prepared by dissolving 1 g of diphenylamine hydrochloride in 38 g of the above paraffinic mineral oil was added, and the mixture was stirred and cooled to room temperature with stirring. Next, the mixture was kneaded two or three times with a three-roll mill to prepare a lithium soap-based grease of NLGI consistency grade No. 1. The degree of oil separation, the degree of mixing penetration, the dropping point, and the amount of evaporation of the produced grease were measured in the same manner as in Example 1. As a result, the degree of oil separation was 7.
1 wt%, mixing consistency 326, drop point 168 ° C,
The amount of evaporation was 3.6% by weight. The grease produced in this manner was subjected to a friction test while being heated in the evaluation apparatus shown in FIG. As a result, the maximum coefficient of static friction was 5.6.

Comparative Example 3 The grease produced in Comparative Examples 1 and 2 was filled in each bearing of the actuator section 9 and the bearing of the spindle 2 in the magnetic disk drive in the same manner as in Example 7, and the same conditions as in Example 7 were used. Was evaluated. Comparative Example 1,
It was found that none of the magnetic disk devices in which the bearings were filled with the respective greases of No. 2 could not be restarted, and that strong stiction (adhesion) due to grease scattered matter occurred.

[0041]

According to the present invention, it is possible to prevent the grease from scattering from the bearing of the actuator section and the bearing of the spindle. As a result, a stable operation can be maintained even in a magnetic disk device in which the flying height of the head is reduced and the magnetic disk device is easily affected by contamination, and high reliability can be ensured.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an apparatus for evaluating a friction test performed in Examples 1, 2, 3, 4, 5, 6, and Comparative Examples 1 and 2 of the present invention.

FIG. 2 is a schematic diagram of a magnetic disk drive evaluated in Example 7 of the present invention and Comparative Example 3.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Magnetic disk, 2 ... Spindle, 3 ... Disk holder, 4 ... Head slider, 5 ... Arm, 6 ... Motor, 7 ... Cord heater, 8 ... Bar heater, 9 ... Actuator, 10 ... Load arm.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yutaka Ito 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd.

Claims (4)

[Claims] A magnetic disk, a magnetic head slider, a carrier for mounting the magnetic head slider near the surface of the magnetic disk, an actuator, and a spindle motor for rotating the magnetic disk are housed in a container. The lubricating grease used for the actuator and the bearing portion of the spindle motor has an oil separation of 0 to 0.5 wt.
%, A mixing consistency of 220 to 295, a dropping point of 190 ° C. or more, and an evaporation amount of 0.2 wt% or less. 2. A magnetic disk, a magnetic head slider, a carrier for mounting the magnetic head slider near the surface of the magnetic disk, an actuator, and a spindle motor for rotating the magnetic disk are housed in a container. In the magnetic disk drive, the lubricating grease used in the actuator and the bearing portion of the spindle motor is one or more of an amine compound or a phenol compound as an additive, and a polyol ester oil or a phenyl ether oil as a base oil. , A fluorine-based oil, or a trimellitic acid ester oil, and a thickening agent selected from the group consisting of lithium soap, lithium composite soap, and a urea compound. 3. A container containing a magnetic disk, a magnetic head slider, a carrier for mounting the magnetic head slider near the surface of the magnetic disk, an actuator, and a spindle motor for rotating the magnetic disk. The lubricating grease used for the actuator and the bearing portion of the spindle motor has an oil separation of 0 to 0.5 wt.
%, Mixing consistency 220-295, dropping point 190 ° C or more, evaporation amount 0.2 wt% or less, additive is one or more of amine compounds or phenolic compounds, base oil is polyol ester oil, phenyl ether type One or more of oil, fluorine-based oil, trimellitate oil,
A magnetic disk drive characterized in that the thickener is any one of lithium soap, lithium composite soap and urea compound. 4. A magnetic disk, a magnetic head slider, a carrier for mounting the magnetic head slider near the surface of the magnetic disk, and an actuator for moving the carrier and the magnetic head slider on the surface of the magnetic disk. And a maximum static friction coefficient between the magnetic head slider and the magnetic disk at the time of starting the device is 1.2 in a magnetic disk device in which a spindle motor for rotating the magnetic disk is accommodated in a container.
A magnetic disk drive characterized by the following.