WO2007010845A1

WO2007010845A1 - Lubricant for oil retaining bearing

Info

Publication number: WO2007010845A1
Application number: PCT/JP2006/314040
Authority: WO
Inventors: Hideto Kammurai; Shukichi Shimoda; Katsumi Hashimoto
Original assignee: Idemitsu Kosan Co., Ltd.
Priority date: 2005-07-15
Filing date: 2006-07-14
Publication date: 2007-01-25
Also published as: CN101223263A; KR20080028933A; JP2007046030A; CN101223263B; JP5074687B2; US20090069204A1

Abstract

Disclosed is a lubricant for oil retaining bearings which contains 1-100% by mass of an ion liquid. This lubricant for oil retaining bearings has a low vapor pressure while being at low risk of inflammability. In addition, this lubricant is excellent in heat resistance and suppressed in generation of a low volatile component or a decomposed gas during use. Alternatively, the lubricant for oil retaining bearings may have antistatic properties and is capable of grounding static charges generated by streaming electrification.

Description

Specification

Oil-impregnated bearing lubricant

Technical field

[0001] The present invention relates to a lubricant for oil-impregnated bearings. More specifically, the present invention includes an ionic liquid in the base oil, has a low vapor pressure, has a low risk of ignition, is excellent in heat resistance, and can suppress generation of low volatile components and decomposition gas during use. The present invention relates to a lubricant for oil-impregnated bearings or an oil-impregnated bearing lubricant having antistatic properties, which contains an ionic liquid as an antistatic agent and can ground static electricity generated by flow electrification of the lubricant.

Background art

In recent years, as a spindle motor bearing typified by a magnetic disk or an optical disk, there are an increasing number of cases where a slide bearing such as a fluid bearing or a sintered oil-impregnated bearing is used to provide silence and durability. These bearings are characterized in that the shaft and the inner surface of the bearing are separated by lubricating oil to support the load applied to the shaft and reduce the friction between the shaft and the bearing. Therefore, it can be said that the performance of these bearings largely depends on the performance of the lubricating oil.

The performance required for the lubricating oil of these plain bearings includes viscosity, durability and antistatic properties. Of these, viscosity is indispensable for determining power loss and bearing rigidity of spindle motors, but recent information related equipment [especially CD, DV D, HDD, laser printer (polygon mirror) Since the spindle motor used in the industry is increasing in speed (10,000 to 50,000 revolutions) year by year, a low viscosity with low power loss at high speed is selected as a recent trend. On the other hand, when the viscosity of the lubricating oil decreases, the amount of oil evaporation generally increases. Therefore, easy adoption of low-viscosity oil leads to oil loss, poor lubrication in the bearing, and in the worst case, damage to the bearing. Considering this point, as a base oil for bearing lubricating oil satisfying low viscosity and low evaporation, for example, Patent Document 1 is an ester compound, Patent Document 2 is a monoester, and Patent Document 3 is a carbonate. Ester, Patent Document 4 and Patent Document 5 include polya-olefin combined with ester, Patent Document 6 includes diester and polyol ester, Patent Document 7 includes neopentyldarlicol ester, Patent Document 8 Is an aromatic ester or diester, Patent Document 9 is a monoester, There are many proposals such as special diesters such as oxalic acid, malonic acid, and succinic acid.

On the other hand, in a sliding bearing, the shaft and the bearing separated by the oil film are completely in non-contact. Therefore, static electricity is generated by flow electrification, and these electrical discharges can cause trouble to important electronic components (MR heads of hard disks). Therefore, for slide bearings used in precision instruments such as magnetic disks, it is particularly necessary to ground static electricity to protect electronic and magnetic parts. From this point of view, the conventional lubricating oil for bearings shown above is satisfactory in low viscosity and low evaporability, but it can easily generate static electricity with a large volume resistivity. Hold

On the other hand, examples of blending conductive fine particles made of metal or metal oxide have been reported (see, for example, Patent Documents 11 and 12), but an oil containing such fine particles can start and stop motors. Sometimes fine particles intervene on the friction surface, which may cause abnormal friction of the bearing.

In addition, an example in which an organic metal salt such as sulfonic acid, phenate, or salicylate is added as a lubricating oil not containing such metal particles has been proposed (see Patent Document 13). However, these organic metal salt antistatic agents do not exhibit antistatic properties unless added in a large amount. In addition, there is a problem in that it deteriorates and deteriorates when used for a long time, and produces an inorganic salt (sludge) insoluble in oil.

[0004] By the way, in recent years, organic ionic liquids composed of cations and arions have a series of ethylmethylimidazolium salt strengths with different arions and have excellent thermal stability and high ionic conductivity. However, since it has been reported that it becomes a stable liquid even in air (for example, see Non-Patent Document 1), it has attracted attention, its thermal stability (flammability and flame retardancy), high ion density (high ion conductivity) Application studies are actively conducted for various uses, for example, electrolytes for solar cells (see, for example, Patent Document 14), extraction / separation solvents, reaction solvents, and the like.

This ionic liquid is intermolecularly attracted by intermolecular attractive force like a molecular liquid, and is connected by a strong ionic bond rather than a volatile liquid. It is a stable liquid against water. Therefore, even if it has a low viscosity, it is low evaporative and further resistant Due to its excellent thermal properties, it is attracting attention as a base oil for lubricating oils that can satisfy the advanced requirements of the future.

Furthermore, since ionic liquids are composed of positive and negative charged cations and ions, they also have electrical characteristics such as being oriented with respect to the electric field and forming an electric double layer on the electrode surface. . This suggests that such characteristics of ionic liquids may develop and have some impact on frictional properties.

[0005] As an example of using such an ionic liquid as a lubricant, a lubricant is filled in a bearing gap formed between a bearing hole of a sleeve and a shaft inserted into the bearing hole, and the inner surface of the bearing hole Alternatively, in the liquid bearing device having a dynamic pressure generating groove on at least one of the shaft surfaces and the sleeve and the shaft rotating relatively, a fluid obtained by adding an ionic liquid as a conductivity imparting agent to the lubricant A bearing device is disclosed (for example, see Patent Document 15). However, this technology is a technology in which an ionic liquid is added as a conductivity imparting agent to a fluid bearing lubricant, and is not a technology applied to an oil-impregnated bearing lubricant.

[0006] Patent Document 1 Japanese Patent Application Laid-Open No. 11-315292

Patent Document 2 Japanese Unexamined Patent Publication No. 2000-63860

Patent Document 3 Japanese Unexamined Patent Publication No. 2001-107046

Patent Document 4 JP 2001-172656 A

Patent Document 5 JP 2001-240885

Patent Document 6 JP 2001-279284 A

Patent Document 7 JP 2001-316687

Patent Document 8 JP 2002-97482 A

Patent Document 9 JP 2002-146381 (paragraph [0007])

Patent Document 10: Japanese Unexamined Patent Application Publication No. 2002-155944

Patent Document 11: Japanese Patent Laid-Open No. 10-30096

Patent Document 12: JP-A-11 315292 (paragraph [0023])

Patent Document 13: Japanese Patent Laid-Open No. 2001-234187

Patent Document 14: Japanese Patent Laid-Open No. 2003-31270

Patent Document 15: Japanese Unexamined Patent Application Publication No. 2004-183868 Non-Patent Document 1: “J. Chem. Soc. Chem. Commun. J, 965 (1992) Disclosure of Invention

Problems to be solved by the invention

[0007] Under such circumstances, the present invention provides an oil-impregnated bearing that has low risk of ignition due to low vapor pressure, has excellent heat resistance, and can suppress generation of low-volatile components and decomposition gas during use. It is an object of the present invention to provide a lubricant for oil-impregnated bearings having antistatic properties and capable of grounding static electricity generated due to flow electrification of the lubricant. Means for solving the problem

[0008] As a result of intensive studies to develop a lubricant for oil-impregnated bearings having the above-mentioned preferred properties, the present inventors have achieved the object by using a lubricant containing an ionic liquid in a predetermined ratio. Found to get. The present invention has been completed based on such knowledge. That is, the present invention

(1) Ionic liquid 1-: Lubricant for oil-impregnated bearing, characterized by containing L00% by mass,

(2) The oil-bearing bearing lubricant according to (1) above, wherein the base oil contains ionic liquid 50-: L00% by mass,

(3) The oil-impregnated bearing lubricant according to (2) above, wherein the ionic liquid used in the base oil has a pour point of 0 ° C or lower,

(4) The oil-impregnated bearing lubricant according to (1) above, which contains an ionic liquid as an antistatic agent,

(5) The lubricant for oil-impregnated bearings according to any one of (1) to (4) above, wherein the volume resistivity at 25 ° C is 1 X 10 ¹⁰ Ω'cm or less,

[0009] (6) Ionic liquid force general formula (I)

(Z ^{p +} ) '(A ^q —) (1)

k m

(In the formula, Z ^{P +} represents a cation, A ^q — represents a-on, p, q, k, m, p X k and q X m are each an integer of 1 to 3, and p X k = q When Xm is satisfied and k or m is 2 or more, Z or A may be the same or different.

(7) —in the general formula (1), p, k, q and m are all compounds represented by the above formulas (1) to (5): The oil-impregnated bearing lubricant according to (6) above, (8) The oil-impregnated bearing lubricant according to any one of (1) to (5), wherein the ionic liquid is a zwitterionic type in which a cation and a cation are covalently fixed.

(9) The lubricant for oil-impregnated bearings according to any one of the above (6) to (8), wherein the ionic liquid has a cation having a nitrogen atom as an ion center,

(10) The lubricant for oil-impregnated bearings according to any one of (1) to (9) above, wherein the kinematic viscosity at a temperature of 40 ° C is 1 to: LOOOmm ² Zs, and

(11) The lubricant for oil-impregnated bearings according to any one of (1) to (10), wherein the bearing is impregnated with a metal-based porous body, a plastic-based porous body, or a ceramic-based porous body.

(12) An oil-impregnated bearing characterized by using the lubricant for oil-impregnated bearings according to any one of (1) to (11) above, and

(13) Provided is a motor unit characterized by using the oil-impregnated bearing described in (12) above.

The invention's effect

[0010] According to the present invention, the base oil contains an ionic liquid, the vapor pressure is low, the risk of ignition is low, the heat resistance is excellent, and the generation of low volatile components and decomposition gas during use is suppressed. It is possible to provide a lubricant for oil-impregnated bearings or an oil-impregnated bearing lubricant having antistatic properties, which contains an ionic liquid as an antistatic agent and can ground static electricity generated by fluid charging of the lubricant.

Brief Description of Drawings

FIG. 1 is an enlarged cross-sectional view for explaining an example of a spindle motor to which an oil-impregnated bearing lubricant of the present invention is applied.

Explanation of symbols

[0012] 1: Housing holder

2: Cylindrical part

3: Bearing

4: Middle escape section

5: Motor shaft 8: Magnet

9: Multilayer core

10: Coil

11: Turntable

B: Base

M: Rotating media

BEST MODE FOR CARRYING OUT THE INVENTION

[0013] The lubricant for oil-impregnated bearing of the present invention is characterized by containing ionic liquid 1 to: LOO mass%.

In the present invention, the ionic liquid is a type in which a cation and a cation are bonded by an ionic bond (hereinafter sometimes referred to as ionic liquid I), and a cation and a ionic bond are covalently bonded. A fixed type, that is, a twin ion type (hereinafter sometimes referred to as ionic liquid II) can be used.

As the ionic liquid I, for example, the general formula (1)

(Z ^{p +} ) '(A ^q —) (1)

k m

The compound represented by these can be used.

The ionic liquid I is one in which p, k, q, and m are all 1 in the general formula (1), that is, the general formula (I a)

Ζ + · Α— (I -a)

(In the formula, Z + represents a cation and A- represents a-on.)

Is preferred.

[0014] The cation represented by Z + is not particularly limited, and any one of known cations as a cation of a conventional ionic liquid can be appropriately selected. For example, the general formula [0015]

(In the formula, Ri to R ¹² are groups in which a hydrogen atom, an alkyl group having 1 to 18 carbon atoms which may have an ether bond, and an alkoxyl group having 1 to 18 carbon atoms are also selected; R ¹² may be the same or different.

[0016] is preferred. Examples of the alkyl group having 1 to 18 carbon atoms that may have an ether bond of Ri to R ¹² include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, sec- Examples include butyl group, tert-butyl group, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups, and 2-methoxyethyl group. Examples of the alkoxy group having 1 to 18 carbon atoms include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, various pentoxy groups, and various types. Examples include heptoxy groups and various oxy groups. In the present invention, among the cations, a cation having a nitrogen atom as an ion center is preferable.

[0017] On the other hand, there is no particular limitation on the ion represented by A-, and any one of the known ions can be appropriately selected as the conventional ion liquid ion. . For example, BF

Four

, PF—, CH OSO—, (CFH) SO—, (CFH) COO ", NO", CH SO -, (CN) N-, HSO-, CH SO-, CH (CH) SO-, I ", I-, F (HF)-, ((CF

3 2 3 6 5 3 3 6 4 3 3 n n (2n- 1- x)

H] Y ^J 0) C ", ([CFH] Y ^J 0) N— (where Y ¹ represents a carbon atom or a sulfur atom)

X ζ 3 η (2η + 1-χ) χ ζ 2

Υ When ¹ is plural, they may be the same or different. Also, multiple F

η (2η + 1

)) Γ'θ may be the same or different. η is an integer from 0 to 6, X is an integer from 0 to 13, ζ

-χ) χ 2

Is an integer from ^{1 to} 3 when γ ¹ is a carbon atom, and an integer from 0 to 4 when Υ ¹ is a sulfur atom. ), B (CY ² ) ", P (CY ² ) — (wherein Υ ² represents a hydrogen atom or a fluorine atom, and Υ ² is m (2m + l) 4 m (2m + l) 6

When there are a plurality of them, they may be the same or different. m is an integer of 0-6. ) And the following general formula

[Chemical 2]

(Wherein R "to R" are groups selected from a hydrogen atom and (C F H),

n (2n + l-x) x

It may be the same or different. n and X are the same as above. )

[Chemical 3]

(Wherein Rf ¹ is a perfluoroalkyl group, Rf ^{2 to} Rf ⁶ are each independently a fluorine atom, A fluoralkyl group or a perfluorobenzyl group, p is 0 or 1; R 1 and R ¹⁹ each independently represent a halogen atom or a halogenated alkyl group. R ^2Q to R ²² are each independently a hydrogen atom, a hydroxyl group, a mercapto group, an amino group, a carboxy group, a tetrazolyl group, a sulfonic acid group, an alkyl group having 1 to 10 carbon atoms, or a cycloalkyl group having 3 to 10 carbon atoms. Group, a C6-C10 aryl group or a C7-C10 aralkyl group, each group other than a hydrogen atom may have a substituent. )

[0019] The following can be cited.

Of the above key-on A—, PF—, C H OSO—, (C F H) SO—, (C F H)

6 n (2n + l) 3 η (2η + 1-χ) x 3 n (2η + 1-χ) x

COO ", NO-, CH SO-, (CN) N-, HSO-, ([CFH] γ'θ) N- (where Y ¹

3 3 3 2 3 n (2η + 1-χ) x z 2

Represents a carbon atom or a sulfur atom, and when Y ¹ is plural, they may be the same or different. n is an integer from 0 to 6, X is an integer from 0 to 13, z is an integer from ¹ to 3 when Y ¹ is a carbon atom, and an integer from 0 to 4 when Y ¹ is a sulfur atom. ) And the above-mentioned general formulas are more preferable, CH OSO-, (CFH) SO-, (CFH) COO ", NO-

n (2n + l) 3 n (2η + 1-χ) x 3 n (2η + 1-χ) x 3

, CH SO—, (CN) N—, HSO— (wherein n is an integer from 1 to 6 and x is an integer from 0 to 13)

3 3 2 3

And the arone represented by the above general formula is particularly preferred.

[0020] As ionic liquid II (twin type: Zwitterionic type), for example, a general formula

[0021] [Chemical 4]

(In the formula, Ri to R ¹² ′ are a group in which a hydrogen atom, an alkyl group having 1 to 18 carbon atoms and an alkoxyl group having 1 to 18 carbon atoms which may have an ether bond are also selected, and Ri ˜R ¹² ′ may be the same or different, provided that at least one of R ^{1 to} R ¹² ′ is — (CH 2) 2 —SO— or

2 n 3

-(CH) — COO— (n is an integer of 1 or more such that the alkylene group has 1 to 18 carbon atoms.

2 n

is there. ). )

Can be mentioned. In the ionic liquid II, it is preferable that the nitrogen atom is an ionic center as a cation.

In the present invention, the ionic liquids I and II can be contained in the lubricant as a base oil or as an additive. When used as a base oil, the content of the ionic liquid in the base oil is preferably 50 to: L00% by mass, more preferably 70 to: L00% by mass, and even more preferably 90 to: L00% by mass. It is desirable to add to be! /.

When an ionic liquid is used for the base oil, the pour point of the ionic liquid is preferably 0 ° C or lower, more preferably 2.5 ° C or lower. An ionic liquid having such a melting point is, for example, an ion liquid I by appropriately combining the cation Z + and the arion A— in the general formula (Ia), or two or more kinds of ionic liquids. Using a mixture of ionic liquids More can be obtained.

Specific examples of the ionic liquid I represented by the general formula Ζ + · A- used as a base oil include 1-butyl-3-methylimidazole tetrafluoroborate, 1-butyl-3 methylimidazole hexafluoroborate 1-Hexylru 3-Methylimidazolium hexafluorophosphate, 1-Methyl-3-ethylimidazolium bis (fluorosulfol) imide, 1-Methyl-1-propylpyrrolidi-umbis (fluorosulfol) imide 1-Butyl-3-methylimidazolium bis (trifluoromethanesulfol) imide, alkyl pyridinium tetrafluoroborate, alkyl pyridinium hexafluorophosphate

, Alkyl pyridinium bis (trifluoromethanesulfol) imide, alkylammotetrafluororeborate, anolequinoleum hexafnoreo-oral phosphate, anoleumumo-umbis (trifluoromethanesulfol) Imido, N, N Jetyl mono-N-methyl (2-methoxyethyl) ammotetrafluoroborate, N, N Jetyl-N-methyl (2-methoxyethyl) ammonium hexafluorophosphate and N, N di Examples thereof include ethyl N-methyl (2-methoxyethyl) ammonium bis (trifluoromethanesulfol) imide. These ionic liquids can be used alone or in combination of two or more.

Among these, alkyl pyridinium hexafluorophosphate, alkyl pyridinium bis (trifluoromethanesulfol) imide, alkyl ammonium hexafluorophosphate, alkyl ammonium bis (trifluoromethanesulfo- ) Imide, N, N jetyl-N-methyl (2-methoxyethyl) ammonium hexafluorophosphate and N, N jetyl-N-methyl (2-methoxyethyl) ammo-bis (trifluoromethanesulfol) Imido is preferred.

As examples of the specific structure of the ionic liquid I, bis (fluorosulfol) imides are shown below.

[Chemical 5]

When a mixture of two or more kinds of ionic liquids is used, the blending amount of each ionic liquid is preferably 10% by mass or more based on the mixture standard. In ionic liquid I, this mixture is a mixture containing one or more Z + and two or more A-, a mixture containing two or more Z + and one A-, and two or more Z + and two or more A-. The mixture containing is mentioned.

Specifically, a mixture of 1-butyl-3-methylimidazole tetrafluoroborate and 1-butyl 3-methylimidazolium bis (trifluoromethanesulfol) imide, alkyl pyridinium hexafluoride Mixture of lophosphate and alkylpyridumum bis (trifluoromethanesulfol) imide, mixture of alkylammonum bis (trifluoromethanesulfurimide) and 1 butyl 3 methylimidazolium bis (trifluoromethanesulfur) imide , 1-butyl-3-methylimidazole tetrafluoroborate and N, N jetyl-N-methyl (2-methoxyethyl) ammumbis (trifluoromethanesulfol) imide mixture, 1-butyl-3-methylimidazolium Hexafluorolophosphate and N, N—Jetirou N—Methi A mixture of ru (2-methoxyethyl) ammumbis (trifluoromethanesulfol) imide, N, N Jetyl N-methyl (2-methoxyshetyl) ammumbis (trifluoromethanesulfurimide) and alkylpyridyl- For example, a mixture of dimethyltetrafluoroborate and a mixture of N, N jetyl-N methyl (2-methoxyethyl) ammonium bis (trifluoromethanesulfol) imide and alkylpyridi-hexafluorophosphate. It is done.

Of these, a mixture of 1-butyl-3-methylimidazole tetrafluoroborate and N, N-jetyl-N-methyl (2-methoxyethyl) ammo-bis (trifluoromethanesulfurimide), 1-butyl-3 —A mixture of methyl imidazole hexafluorophosphate and N, N jetyl N-methyl (2-methoxyethyl) ammumbis (trifluoromethanesulfoimide), N, N jetyl N-methyl (2 —Methoxy A) Mixtures of ammonium bis (trifluoromethanesulfo) imide and alkylpyridi-umtetrafluoroborate and N, N jetyl-N-methyl (2-methoxyethyl) amino-umbis (trifluoromethanesulfoyl) imide and alkylpyridyl Preference is given to mixtures of muhexafluorophosphate.

[0025] When ionic liquid II (twin type) is used as a base oil, the cation liquid moiety in ionic liquid II and — (CH 2) —SO— or — (CH 2) —COO— (n is an alkylene group) Carbon number

2 n 3 2 n

An integer greater than or equal to 1 such that it is 1-18. Ion having a desired melting point can be obtained by appropriately combining the key-on moieties represented by), or by using a mixture of two or more ionic liquids II or a mixture of ionic liquids II and I. A liquid can be obtained.

When ionic liquid II is used for the base oil, specific examples of ionic liquid II include 1-methyl 1,3 imidazolium N butanesulfonate and N, N jetyl N methylammonium N butanesulfonate.

[0026] When the ionic liquid I or II is used as an additive in a lubricant, examples of the additive include those that function as an antistatic agent. In this case, the content of ionic liquids I and Z or II in the lubricant is not particularly limited as long as it is 1% by mass or more, but the volume resistivity of the lubricant at 25 ° C is not limited. If it is 1 X 10 ¹⁰ Ω 'cm or less, good antistatic performance will be demonstrated, the generation of static electricity due to fluid flow charging of the lubricant will be suppressed, and electronic parts and magnetic parts due to electrical discharge (MR heads of magnetic disks) Can be prevented. A more preferable volume resistivity is 1 × 10 ⁹ Ω′cm or less.

In addition, when the ionic liquid I or II is used as such an additive, the melting point is not particularly limited as long as it can be dissolved in the base oil.

Ionic liquid used in the present invention, the ion concentration (cation or § - one concentration) is not less 1 mole Z dm ³ or more is preferably from preferably instrument that 2 moles ZDM ³ or more, more preferably 3 mol ZDM ³ or more It is. If the ion concentration is 1 mol Zdm ³ or more, the purpose of the application can be sufficiently achieved.

[0027] In the lubricant for oil-impregnated bearings of the present invention, as the base oil other than the ionic liquid, those that are miscible with the above ionic liquid and those that can dissolve the ionic liquid can be used. Examples of such base oils include polar base oils such as polyalkylene glycols, modified diethers, polyethers, and phosphate esters.

The lubricant for oil-impregnated bearings of the present invention includes various additive agents such as antioxidants, oiliness agents, friction reducers, antifungal agents, metal deactivators, antifoams as long as the effects of the present invention are not impaired. Agents, viscosity index improvers, and the like can be included.

[0028] (1) Examples of the antioxidant include amine-based antioxidants, phenol-based anti-oxidants and sulfur-based anti-oxidants.

Examples of amine-based antioxidants include monoalkyl diphenylamines such as monooctyldiphenylamine and monoanoldiphenylamine, 4,4'dibutyldiamine, 4,4'-dipentyldiphenyl. Dialkyldiphenylamines such as enylamine, 4,4'-dihexyldiphenylamine, 4,4'-diheptyldiphenylamine, 4,4'-dioctyldiphenylamine, 4,4'-diino-diphenylamine, tetrabutyl Polyalkyldiphenylamines such as diphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine, tetranonyldiphenylamine, α-naphthylamine, phenyl-α α-naphthylamine, butylphenol-α-naphthylamine, Pentylphenol a naphthylamine, hexylphenyl-α naphthylamine, heptylph Examples thereof include naphthylamines such as enyl a naphthylamine, octylphenyl-α, naphthylamine, and nonylphenyla-naphthylamine. Among them, dialkyldiphenylamine is preferable.

[0029] Examples of phenolic antioxidants include monophenols such as 2,6 di-tert-butyl-4-methylphenol, 2,6-ditertbutyl-4-ethylphenol, 4,4'-methylenebis (2,6 tert-butylphenol) and 2,2,1-methylenebis (4-ethyl-6-tertbutylphenol) and the like.

Examples of the sulfur-based antioxidation agent include phenothiazine, pentaerythritol monotetraxone (3-laurylthiopropionate), bis (3,5-tert-butyl-4-hydroxybenzyl) sulfide, thiojetylene bis ( 3— (3,5-Di-tert-butyl-4-hydroxyphenyl)) propionate, 2,6-di-tert-butyl-4 (4,6 bis (octyl) Thio) -1,3,5-triazine-2-methylamino) phenol.

These antioxidants may be used alone or in combination of two or more. The blending amount is usually selected from the range of 0.01 to L0 mass%, preferably 0.03 to 5 mass%, based on the total amount of lubricant.

(2) Examples of oil-based agents include aliphatic saturated and unsaturated monocarboxylic acids such as stearic acid and oleic acid, polymerized fatty acids such as dimer acid and hydrogenated dimer acid, ricinoleic acid, 12-hydroxystearic acid Aliphatic saturated and unsaturated monoalcohols such as hydroxy fatty acids such as lauryl alcohol and oleyl alcohol, aliphatic saturated and unsaturated monoamines such as stearylamine and oleylamine, aliphatic saturated and such as lauric acid amide and oleic acid amide Examples thereof include metal salts of various fatty acids such as unsaturated monocarboxylic acid amide, lithium stearate, aluminum stearate, aluminum oleate, and lithium 12-hydroxystearate. The metal of the fatty acid metal salt includes lithium, sodium, potassium, copper, silver, magnesium, calcium, zinc, aluminum, iron and the like.

These oily agents may be used alone or in combination of two or more. The blending amount is usually selected from the range of 0.01 to: L0 mass%, preferably 0.1 to 5 mass%, based on the total amount of the lubricant.

[0031] (3) As the friction modifier, those generally used as oiliness agents or extreme pressure agents can be used, and in particular, phosphate esters, phosphate ester amine salts, and sulfur-based extreme pressure agents. Preferably mentioned.

Examples of phosphoric acid esters include phosphoric acid esters, acidic phosphoric acid esters, phosphorous acid esters, and acidic phosphorous acid esters represented by the following general formulas (Π) to (VI).

[0032] [Chemical 6]

R ²³ 0-P = 0 (IV)

(OH) ₂

R ²³ 0,

: P OH (VI)

R ²⁴ ○ z In the above general formulas (II) to (VI)! /, R ^{23 to} R ²⁵ are alkyl groups, alkyl groups, alkylaryl groups and arylalkyl groups having 4 to 30 carbon atoms. R ^{23 to} R ²⁵ may be the same or different.

Examples of the phosphate ester include triaryl phosphate, trialkyl phosphate, trialkyl aryl phosphate, triaryl alkyl phosphate, trialkyl phosphate, and the like, for example, triphenyl phosphate, tricresyl phosphate, benzenoresiphenolate. Phosphate, ethinoresin finiole phosphate, tributinorephosphate, ethinoresin butinorephosphate, credinoresin finienophosphate, dicresino lefeninorephosphate, ethino lefe-norresifere-nore phosphate, di (ethino ref eno refe Propyl-phenol diphosphate, di (propyl-phenol) -phosphate, tritinophenol phosphate, tripropinole Eninophosphate, Butinolephenol phosphate, Di (butylphenol) phosphate, Tributylphenol phosphate, Trihexyl phosphate, Tri (2-ethylhexyl) phosphate, Tridecyl phosphate, Examples include trilauryl phosphate, trimyristyl phosphate, trivalmityl phosphate, tristearyl phosphate, trioleyl phosphate and the like. [0034] Examples of the acidic phosphate ester include 2-ethylhexyl acid phosphate, ethyl acid phosphate, butyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, isodecyl acid phosphate, lauryl acid phosphate, Examples thereof include tridecyl acid phosphate, stearyl acid phosphate, and isostearyl acid phosphate.

Examples of phosphites include triethyl phosphite, tributyl phosphite, triphenyl phosphite, tricresyl phosphite, tri (norphenyl) phosphite, tri (2-ethylhexyl) phosphite. , Tridecyl phosphite, trilauryl phosphite, triisooctyl phosphite, diphenylisodecyl phosphite, tristearyl phosphite, trioleyl phosphite and the like.

[0035] Examples of the acidic phosphite include dibutyl hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, distearyl hydride mouth phosphite, diphenyl hydrogen phosphite and the like. it can. Of the above phosphoric acid esters, tricresyl phosphate and triphenyl phosphate are preferred.

Further, examples of amines that form amine salts with these include, for example, general formula (VII) R ² . NH · · · (VII)

P 3-p

(In the formula, R ²⁶ represents an alkyl group or a alkyl group having 3 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, an aryl group having 7 to 30 carbon atoms, or a hydroxy group having 2 to 30 carbon atoms. an alkyl group, or shows a 2 or 3. also, if R ²⁶ is plural, R ²⁶ may be different even identical.)

And mono-substituted amines, di-substituted amines, and tri-substituted amines. The alkyl group or alkenyl group having 3 to 30 carbon atoms in R ²⁶ in the general formula (VII) may be any of a straight chain, a branched chain, and a cyclic group.

[0036] Examples of mono-substituted amines include butylamine, pentylamine, hexylamine, cyclohexylamine, octylamine, laurylamine, stearylamine, oleylamine, benzylamine, and examples of disubstituted amines include dibutylamine. , Dipentylamine, dihexylamine, dicyclohexylamine, dioctylamine, dilaur Lilamine, distearylamine, dioleylamine, dibenzylamine, stearyl 'monoethanolamine, decyl'monoethanolamine, hexyl' monopropanolamine, benzyl'monoethanolamine, phenol'monoethanolamine, tolyl Examples of tri-substituted amines include tributylamine, tripentylamine, trihexylamine, tricyclohexylamine, trioctylamine, trilaurylamine, tristearylamine, trioleylamine. , Tribenzylamine, dioleyl 'monoethanolamine, dilauryl' monopropanolamine, dioctyl 'monoethanolamine, dihexyl' monopropanolamine, dibutyl 'monopropanolamine, Rail Jetanolamine, Stearyl Dipropanolamine, Lauryl Diethanolamine, Octyl Dipropanolamine, Butyl Diethanolamine, Benzyl Ethanolamine, Phenyl Diethanolamine, Tolyl Dipropanolamine Min, xylyl diethanolamine, triethanolamine, tripropanolamine and the like.

[0037] The sulfur-based extreme pressure agent is not particularly limited as long as it has a sulfur atom in the molecule and can be dissolved or uniformly dispersed in the lubricant base oil to exhibit the extreme pressure agent and excellent friction characteristics. . Examples of such compounds include sulfurized fats and oils, sulfurized fatty acids, sulfurized esters, sulfurized sulfin, dihydro strength rubyl polysulfide, thiadiazole compounds, thiophosphoric acid esters (thiophosphite, thiophosphate), alkylthio strength rubamoyl compounds, Examples thereof include thiocarbamate compounds, thioterpene compounds, dialkylthiodipropionate compounds, and the like. Here, sulfurized fats and oils are obtained by reacting sulfur and sulfur-containing compounds with fats and oils (lard oil, whale oil, vegetable oil, fish oil, etc.), and the sulfur content is not particularly limited, but generally 5-30 The thing of the mass% is suitable. Specific examples thereof include sulfurized lard, sulfurized rapeseed oil, sulfurized castor oil, sulfurized soybean oil, and sulfurized rice bran oil. Examples of the sulfurized fatty acid include sulfur oleate and the like, and examples of the sulfur ester include methyl sulfate oleate and sulfur gluten free octyl fatty acid octyl.

[0038] As the olefin sulfide, for example, the following general formula (VIII)

R ²⁷ — S— R ²⁸ '.' (Ring)

(Wherein R ²⁷ is a alkenyl group having 2 to 15 carbon atoms, R ²⁸ is an alkyl group having 2 to 15 carbon atoms, or Represents a alkenyl group, and q represents an integer of 1 to 8. )

The compound etc. which are represented by these can be mentioned. This compound is obtained by reacting an olefin having 2 to 15 carbon atoms or a dimer to tetramer thereof with a sulfurizing agent such as sulfur or sulfite sulfur. Examples of the olefin include propylene, isobutene and diisobutene. Etc. are preferable. As dihydrocarbyl polysulfide, the following general formula (IX)

R ²⁹ — S -R ^30- · · (IX)

(In the formula, R ²⁹ and R ^3Q are each an alkyl group having 1 to 20 carbon atoms or a cyclic alkyl group, an aryl group having 6 to 20 carbon atoms, an alkylaryl group having 7 to 20 carbon atoms, or 7 to 20 carbon atoms. And they may be the same or different from each other, r represents an integer of 1 to 8.)

It is a compound represented by these. Here, when R ²⁹ and R ^3Q are alkyl groups, they are called alkyl sulfides.

In the above general formula (IX), R ²⁹ and R ^3Q are methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, Various benzyl groups, various hexyl groups, various heptyl groups, various octyl groups, various nonyl groups, various decyl groups, various dodecyl groups, cyclohexyl groups, cyclooctyl groups, phenol groups, naphthyl groups, tolyl Examples of the dihydrocarbyl polysulfide include dibenzyl polysulfide, various dinol polysulfides, various didodecyl polysulfides, various dibutyl polysulfides, various dioctyl polysulfides, and the like. Diphenyl-polysulfide, dicyclohexyl polysulfide, etc. are preferred. Can be mentioned.

As the thiadiazole compound, for example, the following general formula (X)

[0040] [Chemical 7] ■ ■ ■ (X)

(In the formula, R ³¹ and R ³² each represent a hydrogen atom and a hydrocarbon group having 120 carbon atoms, and f and g each represents an integer of 0 8.)

[0041] A 1,3,4-thiadiazole compound, a 1,2,4-thiadiazole compound, a 1,4,5-thiadiazole compound, or the like represented by

Examples of the thiadiazole compounds include 2,5 bis (n xyldithio) 1,3,4-thiadiazole, 2,5 bis (n-octyldithio) 1,3,4-thiadiazole, 2,5 bis (n-no- 1,3,4-thiadiazole, 2,5 bis (1,1,3,3-tetramethylbutyldithio) 1,3,4-thiadiazole, 3,5 bis (n xyldithio) 1,2,4 -Thiadiazole, 3, 6 bis (n-octyldithio) 1, 2, 4-thiadiazole, 3,5 bis (n-nordithio) 1, 2, 4-thiadiazole, 3, 5 bis (1, 1, 3, 3 —Tetramethylbutyldithio) 1, 2, 4-thiadiazole, 4, 5 bis (n-octyldithio) 1, 2, 3 thiadiazole, 4,5 bis (n nonyl dithio) 1, 2, 3 thiadiazole, 4, 5 Bis (1, 1, 3, 3-tetramethylbutyldithio) -1, 2, 3 it can.

Examples of thiolic acid esters include alkyl trithiophosphite, aryl or alkyl arylthiophosphate, zinc dilauryl dithiophosphate, and lauryl trithiophosphite and triphenylthiophosphate are particularly preferred! /.

Examples of the alkylthio strength ruba moile compound include, for example, the following general formula (XI)

[0042] [Chemical 8]

(In the formula,! ^ ~ R represents an alkyl group having 1-20 carbon atoms, and h represents an integer of 1-8).

[0043] Examples of the alkylthio-powered rubermoyl compound include bis (dimethylthio-powered rubermoyl) monosulfide, bis (dibutylthio-powered rubermoyl) monosulfide, bis (dimethylthio-powered rubermoyl) disulfide, bis (dibutylthio-powered rubermoyl) disulfide, bis ( Preferred examples include diamylthiothiolvamoyl) disulfide, bis (dioctylthioleorubamoyl) disulfide and the like.

[0044] Further, as the thiocarbamate compound, for example, a zinc dialkyldithiocarbamate, and as the thioterpene compound, for example, a reaction product of phosphorus pentasulfide and pinene, dialkylthiodipropionate As the compound, for example, dilaurylthiodipropionate, distearylthiodipropionate and the like can be mentioned. Of these, thiadiazole compounds and benzyl sulfide are preferable from the viewpoints of extreme pressure, friction characteristics, thermal acid stability, and the like.

These friction modifiers may be used alone or in combination of two or more. The blending amount is usually selected in the range of 0.01 to 10% by mass, preferably 0.05 to 5% by mass on the basis of the total amount of lubricant from the viewpoint of balance between effect and economy.

[0045] (4) Examples of the antifungal agent include alkyl such as dodece-lucosuccinic acid half ester, octadece-succinic anhydride, dodece-succinic acid amide, etc., alk-succinic acid derivative, sorbitan monooleate Polyalcohol partial esters such as glycerin monooleate and pentaerythritol monooleate, amines such as rosinamine, N-oleylsarcosine and anolequinoleamine, dianolenorephosphiteamine salts, etc. It is usable. These may be used alone or in combination of two or more. The preferred blending amount of these antifungal agents is in the range of 0.01 to 5% by mass, particularly preferably in the range of 0.05 to 2% by mass, based on the total amount of the lubricant. [0046] (5) As the metal deactivator, for example, benzotriazole-based, thiadiazole-based, gallate-based compounds, and the like can be used.

A preferable blending amount of these metal deactivators is 0.01 to 0.4% by mass based on the total amount of the lubricant, and a range of 0.01 to 0.2% by mass is particularly preferable.

(6) As an example of the antifoaming agent, liquid silicone is suitable, and methylsilicone, fluorosilicone, and polyacrylate can be used.

A preferable blending amount of these antifoaming agents is 0.0005-0.01% by mass based on the total amount of the lubricant.

(7) Examples of viscosity index improvers include olefin copolymers such as polyalkylmethallate, polyalkylstyrene, polybutene, ethylene-propylene copolymer, styrene-gen copolymer, and styrene-maleic anhydride ester copolymer. Can be used. A preferable blending amount of these viscosity index improvers is 0.1 to 15% by mass based on the total amount of the lubricant, and a range of 0.5 to 7% by mass is particularly preferable.

[0047] In the lubricant for oil-impregnated bearings of the present invention, the kinematic viscosity at a temperature of 40 ° C is preferably in the range of 1 to: L000 mm ² Zs. If this kinematic viscosity is in the above range, evaporation loss, power loss due to viscous resistance, etc. can be suppressed. A more preferable kinematic viscosity at a temperature of 40 ° C. is 5 to 300 mm ² Zs.

The pour point is preferably 10 ° C. or less, more preferably 20 ° C. or less, and even more preferably 30 ° C. or less, from the viewpoint of suppressing viscous resistance at low temperatures.

The viscosity index is preferably 80 or more, more preferably 100 or more, and still more preferably 120 or more, from the viewpoint of preventing the viscosity change with respect to temperature from becoming too large.

The 5% mass loss temperature is preferably 350 ° C or higher, more preferably 380 ° C or higher. The flash point is preferably 200 ° C or higher, more preferably 250 ° C or higher, particularly preferably 300 ° C or higher. Further, the acid value is used to prevent corrosion of metal-based members to which the lubricant of the present invention is applied. From the viewpoint, lmgKOHZg or less is more preferable, 0.5 mgKOHZg or less is more preferable, and 0.3 mgKOHZg or less is more preferable.

[0048] The lubricant for oil-impregnated bearings of the present invention comprises a metal-based porous body, a plastic-based porous body, and a ceramic. It is used by impregnating a bearing made of a rubber-based porous body. It is particularly suitable for use in sintered oil-impregnated bearings obtained by compacting metal powder.

The accuracy of spindle motors used in information equipment (especially CDs and DVDs) is increasing year by year. Conventionally, there are rolling bearings, hydrodynamic bearings, sintered oil-impregnated bearings, etc. as bearings used in spindle motors for these information devices. From the viewpoint of performance and cost, there is a bearing suitable for each application. Selected and used each time.

By the way, sintered oil-impregnated bearings are remarkably excellent in workability and can be mass-produced. Therefore, rolling bearings have the advantage that they can be offered to the market at a lower cost than hydrodynamic bearings.

However, HDD spindle motors that are used as higher-precision and higher-quality recording devices are required to have high rotational accuracy and high reliability. In order to solve this problem, for example, while applying the characteristics of the sintered oil-impregnated bearing, a lateral pressure in a specific direction is applied to the sintered oil-impregnated bearing, and the motor A special mechanism has been developed to reduce the runout of the rotating shaft as much as possible (Japanese Patent Laid-Open No. 2001-295844). The lubricant of the present invention can be suitably used for such a mechanism.

Next, the mechanism will be described with reference to the attached drawings. Fig. 1 is an enlarged sectional view for explaining an example of a spindle motor, wherein 1 is a housing holder, 3 is a bearing, and 5 is a motor shaft. The housing holder 1 is attached to the base B or the like and has a cylindrical portion 2, and a laminated core 9 in which a coil 10 is wound is provided on the outer peripheral surface of the cylindrical portion 2.

The bearing 3 is configured by compacting metal powder such as copper into a size that can be inserted into the housing holder 1, sintering the powder, and then impregnating the lubricant for oil-impregnated bearing of the present invention, The intermediate relief portion 4 is formed in the middle of the shaft hole to form a so-called “medium relief” center-free type, and the motor shaft 5 is supported at both ends in the length direction.

The motor shaft 5 has a metal rod force of an outer diameter that can be supported in the bearing 3, and the outer portion of the laminated core 9 and the coil 10 is disposed on the outer side of the laminated core 9 and the coil 10 via a holding member 6 at a portion near the tip located on the output side of the motor. A rotor 7 with magnet 8 is attached to the body at the position corresponding to the above-mentioned laminated core 9 on the inner periphery side, and the HDD is attached to the tip of the HDD. Mede The hub to which the M is installed is also constructed as a single unit.

[0050] Further, as a means for applying a lateral pressure in a specific direction to the motor shaft 5 supported by the oil-impregnated bearing 3 in which metal powder is powder-sintered, a laminated layer fixed at symmetrical positions with the motor shaft 5 interposed therebetween. Of the cores 9, the core 9 on one side is displaced in the direction of the motor shaft 5 (closer to the turntable 11) from the a-line position to the b-line position by a distance t−t. By tilting the laminated core 6 in this way, the rotor 7 that rotates at a high speed can be constantly urged in the direction of arrow P, and as a result, a lateral pressure is always applied to the motor shaft 5 in a specific direction (arrow Y direction). can do.

In this way, by applying a lateral pressure in a specific direction to the motor shaft, shaft runout with respect to the oil-impregnated bearing obtained by compacting and sintering metal powder can be suppressed.

[0051] The lubricant for oil-impregnated bearings of the present invention can use a base oil containing 50% by mass or more of an ionic liquid. In this case, there is little risk of ignition due to low vapor pressure, and heat resistance is improved. It is excellent and can suppress generation of low volatile components and decomposition gas during use. In addition, an ionic liquid may be included as an additive such as an antistatic agent. In this case, static electricity generated by fluid charging of the lubricant can be grounded. Of course, such a function is naturally exhibited even when an ionic liquid is used for the base oil.

The lubricant for oil-impregnated bearings of the present invention can be applied to various home appliance motors and in-vehicle motors. The motors for household appliances to which the lubricant for oil-impregnated bearings of the present invention can be applied include floppy disk drives, CD drives, MO drives, DVD drives, hard disk drives, cooling or wind fan motors, polygon mirror drives, mobile phones, etc. There are vibration motors and optical lens stepping motors.

In-vehicle motors to which the lubricant for oil-impregnated bearings of the present invention can be applied include light retractable motors, water pumps, wiper motors, headlamp cleaner motors, door lock actuators, motor antennas, power window motors, power seat motors, Mirror motor, telescopic, tilt steering motor, sunroof motor, motor for electric curtain, motor for radiator cooling fan, blower motor, cooling fan motor for air conditioner, servo motor, motor for internal air sensor for auto air conditioner, fuel leak detection sensor Motor, air purifier motor, vehicle height adjustment motor, anti-lock brake motor, idle speed control motor, 4WD differential lock motor, odometer stepping motor Motor, auto drive motor, fuel stop motor, etc.

Since the lubricant for oil-impregnated bearings of the present invention is insoluble in nonpolar solvents such as gasoline, light oil, and kerosene, it is suitable as a motor bearing installed in a fuel tank system. It is particularly suitable for fuel leak detection sensor motors.

Example

Next, the power to explain the present invention in more detail by way of examples The present invention is not limited to these examples. The characteristics of the lubricant should be measured according to the following method.

(1) Kinematic viscosity

Measured according to “Petroleum product kinematic viscosity test method” defined in JIS K2283.

(2) Viscosity index

(3) Pour point

Measured according to JIS K2269.

(4) Total acid value

In accordance with the “lubricating oil neutralization test method” specified in JIS K2501, the potential difference method was used for measurement.

(5) Flash point

Measured by the C.O.C method in accordance with JIS K2265.

(6) 5% mass loss temperature

Using a differential thermal analyzer, the temperature was raised at a rate of 10 ° C Zmin, and the temperature was reduced by 5% from the initial mass. It can be said that the higher the 5% mass reduction temperature, the better the evaporation resistance and heat resistance.

(7) Volume resistivity

Measured according to JIS C2102.

(8) Load resistance test

According to ASTM D 2783, the rotation was performed at 1,800 rpm and room temperature. The load wear index (LWI) was calculated from the maximum non-seizure load (LNL) and the fusion load (WL). This value is large The higher the load resistance, the better.

(9) Abrasion resistance test

According to ASTM D 2783, load 196N, rotation speed 1,200rpm, oil temperature 75. C, Test time was 60 minutes. The average wear scar diameter was calculated by averaging the wear scar diameters of three 1Z2 inch spheres.

[0053] Examples 1 to 6 and Comparative Example 1

A lubricant having the composition shown in Table 1 was prepared and evaluated for various properties. The results are shown in Table 1.

[0054] [Table 1]

(note)

Ionic liquid 1: Butylpyridymumbis (trifluoromethanesulfuryl) imide Ionic liquid 2: N, N-jetyl-N-methyl (2-methoxyethyl) ammo-umbis (trifluoromethanesulfonyl) imide Polyol ester: Ester of trimethylolpropane and fatty acid having 8 or 10 carbon atoms Ionic liquid 3: 1-Ethyl-3-methyl-imidazolium bis (trifluoromethanesulfonyl) imide

Ionic liquid 4: 1 Hexyl 3 Methylimidazolium bis (trifluoromethanesulfol) imide

TCP: tricresino rephosphate

DBDS: Dipenzino Residue Sulfide

[0055] From Table 1, the lubricants of Examples 1 to 5 have a flash point of more than 300 ° C and a 5% mass loss temperature of more than 360 ° C despite the low viscosity. It can be seen that it is excellent in low evaporation and heat resistance. Moreover, it is excellent also in load resistance and abrasion resistance.

On the other hand, Comparative Example 1 has a flash point of 236 ° C, which is lower than those of Examples 1 to 5 and a 5% weight loss temperature of 269.3 ° C, which is compared with Examples 1 to 5. Remarkably low.

[0056] Examples 7-14

A lubricant having the composition shown in Table 2 was prepared, and various properties were evaluated. The results are shown in Table 2.

[0057] [Table 2]

Table 2 1

[0058] [Table 3] Table 2 1

(note)

Ionic liquid 5: N, N-Jetyl-N-methyl (2-methoxyethyl) ammonumuteto lafluoroborate

Ionic liquid 1: Same as footnote in Table 1.

From Table 2, the mixture of the two ionic liquids has an effect of improving the viscosity index and pour point compared to the single one.

[0059] Examples 15 to 17 and Comparative Example 2

A lubricant having the composition shown in Table 3 was prepared and evaluated for various properties. The results are shown in Table 3.

[0060] [Table 4]

Table 3

(note)

Ether base oil: 2-Otachidodecyl decyl ether

Ionic liquid 2: Same as footnote in Table 1.

From Table 3, it can be seen that adding ionic liquid as an additive reduces volume resistivity and imparts antistatic properties.

Industrial applicability

When the lubricant for oil-impregnated bearings of the present invention contains an ionic liquid as the base oil, the vapor pressure is low, the risk of ignition is low, the heat resistance is excellent, and the low volatile components and decomposition during use are reduced. Generation of gas can be suppressed.

In addition, when an ionic liquid is added as an antistatic agent, static electricity generated by fluid charge of the lubricant can be grounded.

The lubricant of the present invention is used by impregnating a bearing having a metal-based porous body, a plastic-based porous body, or a ceramic-based porous body, and is particularly suitable for a sintered oil-impregnated bearing of a spindle motor used in information equipment. Used for.

In addition, the lubricant of the present invention can be applied to various home appliance motors and in-vehicle motors, and is insoluble in nonpolar solvents such as gasoline, light oil, and kerosene, and thus is suitable as a motor bearing installed in a fuel tank system. is there. It is particularly suitable for a fuel leak detection sensor motor.

Claims

The scope of the claims

[I] A lubricant for oil-impregnated bearings containing 1 to 100% by mass of an ionic liquid.

[2] The lubricant for oil-impregnated bearings according to claim 1, wherein the base oil contains an ionic liquid 50-: LOO% by mass.

[3] The lubricant for oil-impregnated bearings according to claim 2, wherein the ionic liquid force used for the base oil has a pour point of 0 ° C or lower.

[4] The lubricant for oil-impregnated bearings according to claim 1, comprising an ionic liquid as an antistatic agent.

[5] The lubricant for oil-impregnated bearings according to any one of claims 1 to 4, wherein the volume resistivity at 25 ° C is 1 X 1 Ο ¹⁰ Ω'cm or less.

[6] The ionic liquid has the general formula (I)

(Z ^{P +} ) · (A ^q —) (I)

k m

(Wherein Z ^{P +} represents a cation, A ^q — represents a-on, p, q, k, m, p X k and q X m are each an integer of 1 to 3, p X k = q X m is satisfied, and when k or m is 2 or more, Z or A may be the same or different.

The lubricant for oil-impregnated bearings according to any one of claims 1 to 5, wherein the lubricant is a compound represented by the formula:

7. The lubricant for oil-bearing bearings according to claim 6, wherein p, k, q, and m are all 1 in the general formula (1).

[8] The lubricant for oil-impregnated bearings according to any one of claims 1 to 5, wherein the ionic liquid is a twin ion type in which a cation and a cation are covalently fixed.

[9] The lubricant for oil-impregnated bearings according to any one of [6] to [8], wherein the ionic liquid has a cation having a nitrogen atom as an ion center.

[10] The lubricant for oil-impregnated bearings according to any one of claims 1 to 9, wherein the kinematic viscosity at a temperature of 40 ° C is 1 to: L000mm ² Zs.

11. The oil-impregnated bearing lubricant according to any one of claims 1 to 10, wherein the bearing is impregnated with a metal porous body, a plastic porous body, or a ceramic porous body.

[12] An oil-containing bearing lubricant according to any one of claims 1 to 11 is used.

[13] A motor unit comprising the oil-impregnated bearing according to claim 12.