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US20090069204A1 - Lubricant for oil retaining bearing - Google Patents

Lubricant for oil retaining bearing Download PDF

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Publication number
US20090069204A1
US20090069204A1 US11/913,182 US91318206A US2009069204A1 US 20090069204 A1 US20090069204 A1 US 20090069204A1 US 91318206 A US91318206 A US 91318206A US 2009069204 A1 US2009069204 A1 US 2009069204A1
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US
United States
Prior art keywords
lubricant
ionic liquid
oil retaining
retaining bearing
oil
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
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US11/913,182
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English (en)
Inventor
Hideto Kamimura
Shukichi Shimoda
Katsumi Hashimoto
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Idemitsu Kosan Co Ltd
Original Assignee
Idemitsu Kosan Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Idemitsu Kosan Co Ltd filed Critical Idemitsu Kosan Co Ltd
Assigned to IDEMITSU KOSAN CO., LTD. reassignment IDEMITSU KOSAN CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HASHIMOTO, KATSUMI, KAMIMURA, HIDETO, SHIMODA, SHUKICHI
Publication of US20090069204A1 publication Critical patent/US20090069204A1/en
Abandoned legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
    • C10M169/04—Mixtures of base-materials and additives
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
    • C10M105/56—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing nitrogen
    • C10M105/58—Amines, e.g. polyalkylene polyamines, quaternary amines
    • C10M105/60—Amines, e.g. polyalkylene polyamines, quaternary amines having amino groups bound to an acyclic or cycloaliphatic carbon atom
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M105/00—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound
    • C10M105/72—Lubricating compositions characterised by the base-material being a non-macromolecular organic compound containing sulfur, selenium or tellurium
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M171/00—Lubricating compositions characterised by purely physical criteria, e.g. containing as base-material, thickener or additive, ingredients which are characterised exclusively by their numerically specified physical properties, i.e. containing ingredients which are physically well-defined but for which the chemical nature is either unspecified or only very vaguely indicated
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/10—Construction relative to lubrication
    • F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
    • F16C33/103—Construction relative to lubrication with liquid, e.g. oil, as lubricant retained in or near the bearing
    • F16C33/104—Construction relative to lubrication with liquid, e.g. oil, as lubricant retained in or near the bearing in a porous body, e.g. oil impregnated sintered sleeve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/10—Construction relative to lubrication
    • F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
    • F16C33/109—Lubricant compositions or properties, e.g. viscosity
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H02K11/40—Structural association with grounding devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K5/00—Casings; Enclosures; Supports
    • H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
    • H02K5/16—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields
    • H02K5/167—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields using sliding-contact or spherical cap bearings
    • H02K5/1675—Means for supporting bearings, e.g. insulating supports or means for fitting bearings in the bearing-shields using sliding-contact or spherical cap bearings radially supporting the rotary shaft at only one end of the rotor
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2215/00—Organic non-macromolecular compounds containing nitrogen as ingredients in lubricant Compositions
    • C10M2215/02—Amines, e.g. polyalkylene polyamines; Quaternary amines
    • C10M2215/04—Amines, e.g. polyalkylene polyamines; Quaternary amines having amino groups bound to acyclic or cycloaliphatic carbon atoms
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2215/00—Organic non-macromolecular compounds containing nitrogen as ingredients in lubricant Compositions
    • C10M2215/22—Heterocyclic nitrogen compounds
    • C10M2215/221—Six-membered rings containing nitrogen and carbon only
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2215/00—Organic non-macromolecular compounds containing nitrogen as ingredients in lubricant Compositions
    • C10M2215/22—Heterocyclic nitrogen compounds
    • C10M2215/223—Five-membered rings containing nitrogen and carbon only
    • C10M2215/224—Imidazoles
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2219/00—Organic non-macromolecular compounds containing sulfur, selenium or tellurium as ingredients in lubricant compositions
    • C10M2219/08—Thiols; Sulfides; Polysulfides; Mercaptals
    • C10M2219/082—Thiols; Sulfides; Polysulfides; Mercaptals containing sulfur atoms bound to acyclic or cycloaliphatic carbon atoms
    • C10M2219/083—Dibenzyl sulfide
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M2223/00—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions
    • C10M2223/02—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions having no phosphorus-to-carbon bonds
    • C10M2223/04—Phosphate esters
    • C10M2223/041—Triaryl phosphates
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C10N2020/02—Viscosity; Viscosity index
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C10N2020/077—Ionic Liquids
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2020/00—Specified physical or chemical properties or characteristics, i.e. function, of component of lubricating compositions
    • C10N2020/01—Physico-chemical properties
    • C10N2020/085—Non-volatile compounds
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/02—Pour-point; Viscosity index
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/06—Oiliness; Film-strength; Anti-wear; Resistance to extreme pressure
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/08—Resistance to extreme temperature
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/18—Anti-foaming property
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/28—Anti-static
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
    • C10N2030/74—Noack Volatility
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/02—Bearings
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
    • C10N2040/00—Specified use or application for which the lubricating composition is intended
    • C10N2040/14—Electric or magnetic purposes
    • C10N2040/18—Electric or magnetic purposes in connection with recordings on magnetic tape or disc
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2202/00—Solid materials defined by their properties
    • F16C2202/30—Electric properties; Magnetic properties
    • F16C2202/32—Conductivity

Definitions

  • the present invention relates to a lubricant for an oil retaining bearing. More specifically, the present invention is directed to a lubricant for an oil retaining bearing which contains an ionic liquid in its base oil and which has a low vapor pressure, low flammability, excellent heat resistance and ability to suppress the emanation of low volatile components and decomposed gases during use, or a lubricant for an oil retaining bearing which contains an ionic liquid as an antistatic agent, which has antistatic property and which is capable of grounding the static electricity generated by flow charging of the lubricant.
  • the lubricating oil for such sliding bearings is required to have suitable viscosity, durability, antistatic property, etc.
  • the viscosity is important because the electric power loss of a spindle motor and the bearing rigidity depend upon the viscosity.
  • a lubricant oil having a low viscosity which permits a reduced loss of electric power during high speed operation, because the rotation speed of spindle motors for recent information related equipments (particularly CD, DVD, HDD and laser printers (polygon mirrors)) increases year by year (to a range of 10,000 to 50,000 rpm).
  • the amount of vaporized oil increases.
  • Patent Document 1 proposes the use of an ester compound
  • Patent Document 2 proposes the use of a monoester
  • Patent Document 3 proposes the use of a carbonic acid ester
  • Patent Document 4 and Patent Document 5 propose the conjoint use of poly( ⁇ -olefin) and an ester
  • Patent Document 6 proposes the conjoint use of a diester and a polyol ester
  • Patent Document 7 proposes the use of a neopentyl glycol ester
  • Patent Document 8 proposes the use of an aromatic ester or a diester
  • Patent Document 9 proposes the use of a monoester
  • Patent Document 10 proposes the use of a specific diester of oxalic acid, malonic acid, succinic acid, etc.
  • a lubricating oil compounded with conductive microparticles of a metal or a metal oxide is reported (see, for example, Patent Documents 11 and 12).
  • a lubricating oil containing such microparticles may cause anomalous wear of the bearing, because the microparticles are present on the sliding surface at the time of starting or stopping the motor.
  • the ionic liquid in which molecules are bound by strong ionic bonding rather than by intermolecular attractive forces as in a molecular liquid, is a liquid which is sparingly volatile, flame retarding and stable against heat and oxidation. Although the ionic liquid has a low viscosity, it has low volatility and excellent heat resistance. Therefore, it attracts much attention as a base oil for a lubricating oil that can satisfy possible future high requirements.
  • the ionic liquid since the ionic liquid is composed of a positively charged cation and a negatively charged anion, it has a specific electrical property such as capability of forming an electric double layer on an electrode surface. There is a possibility that such an electrical property of the ionic liquid might exert a certain influence upon the frictional characteristics thereof.
  • a fluid bearing device which includes a sleeve having a bearing hole, a shaft inserted into the bearing hole with a bearing gap being formed between the bearing hole and the shaft, a dynamic pressure generation groove provided in at least one of an inner periphery of the bearing hole or a surface of the shaft, and a lubricant filled in the bearing gap, wherein the lubricant contains an ionic liquid added as a conductivity imparting agent (see, for example, Patent Document 15).
  • the ionic liquid is added as a conductivity imparting agent to the lubricant for a fluid bearing.
  • This technique does not use an ionic liquid in a lubricant for an oil retaining bearing.
  • Patent Document 1 Japanese Unexamined Patent Application Publication No. H11-315292
  • Patent Document 2 Japanese Unexamined Patent Application Publication No. 2000-63860
  • Patent Document 3 Japanese Unexamined Patent Application Publication No. 2001-107046
  • Patent Document 4 Japanese Unexamined Patent Application Publication No. 2001-172656
  • Patent Document 5 Japanese Unexamined Patent Application Publication No. 2001-240885
  • Patent Document 6 Japanese Unexamined Patent Application Publication No. 2001-279284
  • Patent Document 7 Japanese Unexamined Patent Application Publication No. 2001-316687
  • Patent Document 8 Japanese Unexamined Patent Application Publication No. 2002-97482
  • Patent Document 9 Japanese Unexamined Patent Application Publication No. 2002-146381 (paragraph [0007])
  • Patent Document 10 Japanese Unexamined Patent Application Publication No. 2002
  • Patent Document 11 Japanese Unexamined Patent Application Publication No. H10-30096
  • Patent Document 12 Japanese Unexamined Patent Application Publication No. H11-315292 (paragraph [0023])
  • Patent Document 13 Japanese Unexamined Patent Application Publication No. 2001-234187
  • Patent Document 14 Japanese Unexamined Patent Application Publication No. 2003-31270
  • Patent Document 15 Japanese Unexamined Patent Application Publication No. 2004-183868
  • Non-Patent Document 1 Japanese Unexamined Patent Application Publication No. 2004-183868
  • the present inventors have made an earnest study with a view toward developing a lubricant for an oil retaining bearing having the above-described desired properties and, as a result, have found that the objects can be fulfilled by a lubricant containing a specific proportion of an ionic liquid.
  • the present invention has been completed on the basis of such a finding.
  • the present invention provides:
  • a lubricant for an oil retaining bearing including 1 to 100% by mass of an ionic liquid; (2) A lubricant for an oil retaining bearing as recited in (1) above, including a base oil which contains 50 to 100% by mass of the ionic liquid; (3) A lubricant for an oil retaining bearing as recited in (2) above, in which the ionic liquid contained in the base oil has a pour point of 0° C. or below; (4) A lubricant for an oil retaining bearing as recited in (1) above, in which the ionic liquid is contained as an antistatic agent; (5) A lubricant for an oil retaining bearing as recited in any one of (1) to (4) above, which has a volume resistivity at 25° C. of 1 ⁇ 10 10 ⁇ cm or less; retained bearing, (6) A lubricant for an oil retaining bearing as recited in any one of (1) to (5) above, in which the ionic liquid is a compound represented by the following general formula (I):
  • a lubricant for an oil retaining bearing as recited in (6) above in which p, q, k and m in the general formula (I) are each 1;
  • a lubricant for an oil retaining bearing which contains an ionic liquid as its base oil and which has a low vapor pressure, low flammability, excellent heat resistance and ability to suppress the emanation of low volatile components and decomposed gases during use, or a lubricant for an oil retaining bearing which contains an ionic liquid as an antistatic agent, which has antistatic property and which is capable of grounding the static electricity generated by flow charging of the lubricant.
  • FIG. 1 is an enlarged, cross-sectional view illustrating an example of a spindle motor to which the lubricant for an oil retaining bearing according to the present invention is applied.
  • the lubricant for an oil retaining bearing according to the present invention is characterized in that it contains 1 to 100% by mass of an ionic liquid.
  • the ionic liquid may be of a type in which a cation and an anion are bonded by ionic bonding (hereinafter occasionally referred to as ionic liquid (I)) and of a type in which a cation and an anion are bonded by a covalent bond, namely of a zwitterionic type (hereinafter occasionally referred to as ionic liquid (II)).
  • ionic liquid (I) there may be used for example a compound represented by the following general formula (I):
  • Z p+ represents a cation
  • a q ⁇ represents an anion
  • p, q, k, m, p ⁇ k and q ⁇ m are each an integer of 1 to 3, with the proviso that p ⁇ k equals q ⁇ m and that, when k or m is 2 or more, Z or A may be the same or different, respectively).
  • cations represented by Z + is not specifically limited and any cation may be properly selected from the known cations used in the conventional ionic liquid.
  • cations represented the following general formulas may be preferably used:
  • R 1 to R 12 which may be the same or different, each represent a group selected from a hydrogen atom, alkyl groups having 1 to 18 carbon atoms which may have an ether bond, and alkoxy groups having 1 to 18 carbon atoms.
  • Examples of the alkyl group having 1 to 18 carbon atoms which may have an ether bond and which is represented by R 1 to R 12 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups and a 2-methoxyethyl group.
  • alkoxy group having 1 to 18 carbon atoms examples include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, various pentoxy groups, various heptoxy groups and various octoxy groups.
  • cation groups having a nitrogen atom as the ionic center are preferred among the above-described cations.
  • anion represented by A ⁇ is not specifically limited and any anion may be properly selected from the known anions used in the conventional ionic liquid.
  • Y 1 represents a carbon atom or a sulfur atom, provided that when there are plurality such Y 1 groups, they may be the same or different, and that the plural (C n F (2n+1 ⁇ x )H x )Y 1 O 2 groups may be the same or different; n is an integer of 0 to 6; x is an integer of 0 to 13; and z is an integer of 1 to 3 when Y 1 is a carbon atom and 0 to 4 when Y 1 is a sulfur atom),
  • Y 2 is a hydrogen atom or a fluorine atom, provided that when there are plural such Y 2 groups, they may be the same or different; and m is an integer of 0 to 6), and anions of the following general formulas:
  • R 13 to R 17 which may be the same or different, each represent a group selected from a hydrogen atom and (C n F (2n+1 ⁇ x) H x ); and n and x have the same meanings as above
  • Rf 1 represents a perfluoroalkyl group
  • Rf 2 to Rf 6 each independently represent a fluorine atom, a perfluoroalkyl group or a perfluorobenzyl group
  • p is 0 or 1
  • R 18 and R 19 each independently represent a halogen atom or a halogenated alkyl group
  • R 20 to R 22 each independently represent a hydrogen atom, a hydroxyl group, a mercapto group, an amino group, a carboxyl group, a tetrazolyl group, a sulfonic acid group, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms or an aralkyl group having 7 to 10 carbon atoms, provided that each of the groups other than hydrogen atom can contain a substituent.
  • Rf 1 represents a perfluoroalkyl group
  • C n H (2n+1) OSO 3 ⁇ , (C n F (2n+1 ⁇ x) H x )SO 3 ⁇ , (C n F (2n+1 ⁇ x) H x )COO ⁇ , NO 3 ⁇ , CH 3 SO 3 ⁇ , (CN) 2 N ⁇ , HSO 3 ⁇ (where n is an integer of 1 to 6 and x is an integer of 0 to 13) and the anions of the above general formulas.
  • R 1 to R 12 which may be the same or different, each represent a group selected from a hydrogen atom, alkyl groups having 1 to 18 carbon atoms which may have an ether bonding and alkoxyl groups having 1 to 18 carbon atoms, provided that at least one of R 1′ to R 12′ is —(CH 2 ) n —SO 3 ⁇ or —(CH 2 ) n —COO ⁇ (where n is such an integer of 1 or more that the carbon number of the alkylene groups is 1 to 18).
  • a nitrogen atom be the ionic center.
  • the ionic liquids (I) and (II) may be incorporated into a lubricant as a base oil or as an additive.
  • a base oil it is preferred that the ionic liquid be used in such an amount that the content of the ionic liquid in the base oil is 50 to 100% by mass, more preferably 70 to 100% by mass, still more preferably 90 to 100% by mass.
  • the pour point of the ionic liquid is preferably 0° C. or below, more preferably ⁇ 2.5° C. or below.
  • the ionic liquid having such a melting point is obtainable, for example, by adequately combining the cation Z + with the anion A ⁇ in the general formula (I-a) in the case of the ionic liquid (I) or by using a mixture of at least two kinds of ionic liquids.
  • ionic liquid (I) represented by the formula Z + .A ⁇ and used as a base oil include 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluoroborate, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-methyl-3-ethylimidazolium bis(fluorosulfonyl)imide, 1-methyl-1-propylpyrrolidinum bis(fluorosulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, alkylpyridinium tetrafluoroborate, alkylpyridinium hexafluorophosphate, alkylpyridinium bis(trifluoromethanesulfonyl)imide, alkylammonium tetrafluoroborate, alkylam
  • alkylpyridinium hexafluorophosphate alkylpyridinium bis(trifluoromethanesulfonyl)imide, alkylammonium hexafluorophosphate, alkylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl(2-methoxyethyl)ammonium hexafluorophosphate and N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide are preferred.
  • each of the ionic liquids be present in an amount of at least 10% by mass based on the mixture.
  • the mixture of ionic liquids (I) there may be mentioned a mixture containing one Z + and two or more A ⁇ , a mixture containing two or more Z + and one A ⁇ and a mixture of two or more Z + and two or more A ⁇ .
  • an ionic liquid having a desired melting point is obtainable, for example, by adequately combining a cationic moiety of the ionic liquid (II) with an anionic moiety represented by —(CH 2 ) n —SO 3 ⁇ or —(CH 2 ) n —COO ⁇ (where n is such an integer of one or more that the alkylene group has 1 to 18 carbon atoms), or by using a mixture of two or more kinds of ionic liquids (II) or a mixture of an ionic liquid (II) and an ionic liquid (I).
  • ionic liquid (II) used as a base oil examples include 1-methyl-1,3-imidazolium N-butanesulfonate and N,N-diethyl-N-methylammonium N-butanesulfonate.
  • the additive may function as an antistatic agent.
  • the content of the ionic liquid (i) and/or ionic liquid (II) is suitably 1% by mass or more.
  • the lubricant have a volume resistivity of 1 ⁇ 10 10 ⁇ cm or less at 25° C. because suitable antistatic performance can be obtained so that generation of static electricity due to flow charging of the lubricant is suppressed and, therefore, trouble of electronic parts or magnetic parts (e.g. MR head of hard disk) can be prevented.
  • the volume resistivity is more preferably 1 ⁇ 10 9 ⁇ cm or less.
  • Any ionic liquid (I) or (II) may be used as an additive as described above as long as it is soluble in a base oil.
  • the melting point of the ionic liquid (I) or (II) is not specifically limited.
  • the ionic liquid used in the present invention preferably has an ion concentration (cation or anion concentration) of at least 1 mol/dm 3 , more preferably at least 2 mol/dm 3 , still more preferably at least 3 mol/dm 3 .
  • an ion concentration concentration or anion concentration
  • a base oil capable of being mixed with the ionic liquid or dissolving the ionic liquid may be used in addition to the ionic liquid.
  • Such an additional base oil may be a polar base oil such as of a polyalkylene glycol type, a mono, di or polyether type, and a phosphate ester type.
  • various additives such as an antioxidant, an oiliness improver, a friction modifier, a rust preventing agent, a metal deactivator, an antifoaming agent and a viscosity index improver may be added to the lubricant for an oil retaining bearing as long as the effect of the present invention is not adversely affected.
  • antioxidant there may be mentioned an amine type antioxidant, a phenolic antioxidant and a sulfur-containing antioxidant.
  • amine type antioxidant examples include a monoalkyldiphenylamine type antioxidant such as monooctyldiphenylamine and monononyldiphenylamine; a dialkyl diphenylamine type antioxidant such as 4,4′-dibutyldiphenylamine, 4,4′-dipentyldiphenylamine, 4,4′-dihexyldiphenylamine, 4,4′-diheptyldiphenylamine, 4,4′-dioctyldiphenylamine and 4,4′-dinonyldiphenylamine; a polyalkyldiphenylamine type antioxidant such as tetrabutyldiphenylamine, tetrahexyldiphenylamine, tetraoctyldiphenylamine and tetranonyldiphenylamine; and a naphthylamine type antioxidant such as ⁇ -naphthylamine, phenyl- ⁇ -n
  • phenolic antioxidant examples include a monophenol type antioxidant such as 2,6-di-tert-butyl-4-methylphenol and 2,6-di-tert-butyl-4-ethylphenol; and a diphenol type antioxidant such as 4,4′-methylenebis(2,6-di-tert-butylphenol) and 2,2′-methylenebis(4-ethyl-6-tert-butylphenol).
  • sulfur-containing antioxidant examples include phenothiazine, pentaerythritol-tetrakis(3-lauryl-thiopropionate), bis(3,5-tert-butyl-4-hydroxybenzyl)sulfide, thiodiethylenebis(3-(3,5-di-tert-butyl-4-hydroxyphenyl))propionate and 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazine-2-methylamino)phenol.
  • the above antioxidants may be used alone or in combination of two or more thereof.
  • the antioxidant may be generally used in an amount of 0.01 to 10% by mass, preferably 0.03 to 5% by mass, based on a total weight of the lubricant.
  • Examples of the oiliness improver include aliphatic saturated or unsaturated monocarboxylic acids such as stearic acid and oleic acid; polymerized fatty acids such as dimer acid and hydrogenated dimer acid; hydroxyfatty acids such as ricinoleic acid and 12-hydroxystearic acid; aliphatic saturated or unsaturated monohydric alcohols such as lauryl alcohol and oleyl alcohol; aliphatic saturated or unsaturated monoamines such as stearylamine and oleylamine; aliphatic saturated or unsaturated monocarboxylamides such as lauramide and oleamide; and metal salts of the above-described fatty acids such as lithium stearate, aluminum stearate, aluminum oleate and lithium 12-hydroxystearate.
  • the metals of the fatty acid metal salts include, for example, lithium, sodium, potassium, copper, silver, magnesium, calcium, zinc, aluminum and iron.
  • oiliness improvers may be used singly or in combination of two or more thereof.
  • the compounding amount of the oiliness improver is generally in the range of 0.01 to 10% by mass, preferably 0.1 to 5% by mass, based on the total weight of lubricant.
  • the friction modifier may be those generally used as an oiliness improver or an extreme pressure agent.
  • Illustrative of particularly preferred friction reducing agents are phosphoric esters, amine salts of phosphoric esters and sulfur-containing extreme pressure agents.
  • phosphoric esters examples include phosphoric esters, acid phosphoric esters, phosphorous acid esters and acid phosphorous acid esters which are represented by general formulas (II) to (VI) below.
  • R 23 to R 25 which may be the same or different, each represent an alkyl group, an alkenyl group, an alkylaryl group or an arylalkyl group having 4 to 30 carbon atoms.
  • the phosphoric acid ester may be, for example, a triaryl phosphate, a trialkyl phosphate, a trialkylaryl phosphate, a triarylalkyl phosphate or a trialkenyl phosphate.
  • Specific examples of the phosphoric acid ester include triphenyl phosphate, tricresyl phosphate, benzyl diphenyl phosphate, ethyl diphenyl phosphate, tributyl phosphate, ethyl dibutyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, ethylphenyl diphenyl phosphate, diethylphenyl phenyl phosphate, propylphenyl diphenyl phosphate, dipropylphenyl phenyl phosphate, triethylphenyl phosphate, tripropylphenyl phosphate, butylphen
  • Examples of the acid phosphoric ester include 2-ethylhexyl acid phosphate, ethyl acid phosphate, butyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, isodecyl acid phosphate, lauryl acid phosphate, tridecyl acid phosphate, stearyl acid phosphate and isostearyl acid phosphate.
  • Examples of the phosphorous acid ester include triethyl phosphite, tributyl phosphite, triphenyl phosphite, tricresyl phosphite, tri(nonylphenyl) phosphite, tri(2-ethylhexyl)phosphite, tridecyl phosphite, trilauryl phosphite, triisooctyl phosphite, diphenylisodecyl phosphite, tristearyl phosphite and trioleyl phosphite.
  • Examples of the acid phosphorous acid ester include dibutyl hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, distearyl hydrogen phosphite and diphenyl hydrogen phosphite.
  • Examples of the acid phosphorous acid ester include dibutyl hydrogen phosphite, dilauryl hydrogen phosphite, dioleyl hydrogen phosphite, distearyl hydrogen phosphite and diphenyl hydrogen phosphite.
  • tricresyl phosphate and triphenyl phosphate are particularly preferable.
  • Amines that form amine salts with the above acid phosphorus acid esters may be a monosubstituted amine, a disubstituted amine or a trisubstituted amine, which are represented by the following general formula (VII):
  • R 26 represents an alkyl or alkenyl group having 3 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms or a hydroxyalkyl group having 2 to 30 carbon atoms and p represents 1, 2 or 3 with the proviso that when there are a plurality of such R 26 groups, they may be the same or different.
  • the alkyl or alkenyl group having 3 to 30 carbon atoms represented by R 26 in the above general formula (VII) may be straight chained, branched or cyclic.
  • Examples of the monosubstituted amine include butylamine, pentylamine, hexylamine, cyclohexylamine, octylamine, laurylamine, stearylamine, oleylamine and benzylamine.
  • disubstituted amine examples include dibutylamine, dipentylamine, dihexylamine, dicyclohexylamine, dioctylamine, dilaurylamine, distearylamine, dioleylamine, dibenzylamine, stearylmonoethanolamine, decylmonoethanolamine, hexylmonopropanolamine, benzylmonoethanolamine, phenylmonoethanolamine and tolylmonopropanolamine.
  • trisubstituted amine examples include tributylamine, tripentylamine, trihexylamine, tricyclohexylamine, trioctylamine, trilaurylamine, tristearylamine, trioleylamine, tribenzylamine, dioleylmonoethanolamine, dilaurylmonopropanolamine, dioctylmonoethanolamine, dihexylmonopropanolamine, dibutylmonopropanolamine, oleyldiethanolamine, stearyidipropanolamine, lauryldiethanolamine, octyidipropanolamine, butyliethanolamine, benzyldiethanolamine, phenyldiethanolamine, tolyidipropanolamine, xylyldiethanolamine, triethanolamine and tripropanolamine.
  • the sulfur-containing extreme pressure agent may be any compound as long as the compound has a sulfur atom in the molecule thereof and can be dissolved or uniformly dispersed in a lubricating base oil to exhibit extreme pressure performance and excellent friction characteristics.
  • the sulfur-containing compound include sulfurized fats and oils, sulfurized fatty acid, sulfurized esters, olefin sulfides, dihydrocarbyl polysulfides, thiadiazole compounds, thiophosphoic esters (thiophosphites and thiophosphates), alkyl thiocarbamoyl compounds, thiocarbamate compounds, thioterpene compounds, and dialkyl thiodipropionate compounds.
  • the sulfurized fats or oils may be produced by reaction of a fat or an oil (e.g., lard oil, whale oil, vegetable oil, or fish oil) with sulfur or a sulfur-containing compound.
  • a content of the sulfur is not particularly limited, but 5 to 30% by mass is generally preferable.
  • Concrete examples of the sulfurized fats and oils include a surfurized lard, a sulfurized rape seed oil, a sulfurized castor oil, a sulfurized soybean oil and a sulfurized rice bran oil.
  • Concrete examples of the sulfurized fatty acid include sulfurized oleic acid.
  • Concrete examples of the ester sulfide include sulfurized methyl oleate and sulfurized octyl ester of rice bran fatty acid.
  • R 27 represents an alkenyl group having 2 to 15 carbon atoms
  • R 28 represents an alkyl or alkenyl group having 2 to 15 carbons atoms and q is an integer of 1 to 8.
  • These compounds may be produced by reaction between olefins having 2 to 15 carbon atoms or a dimer to tetramer thereof and a sulfidizing agent such as sulfur or sulfur chloride.
  • olefins are propylene, isobutene and diisobutene.
  • the dihydrocarbyl polysulfide may be a compound represented by the following general formula (IX):
  • R 29 and R 30 which may be the same or differen, each represents an alkyl or cyclic alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkylaryl group having 7 to 20 carbon atoms, or an arylalkyl group having 7 to 20 carbon atoms and r is an integer of 1 to 8.
  • R 29 and R 30 is an alkyl group
  • such a compound is called an alkyl sulfide.
  • R 29 and R 30 in the general formula (IX) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, various pentyl groups, various hexyl groups, various heptyl group, various octyl group, various nonyl group, various decyl group, various dodecyl group, a cyclohexyl group, a cyclooctyl group, a phenyl group, a naphthyl group, a tolyl group, a xylyl group, a benzyl group and a phenethyl group.
  • dihydrocarbyl polysulfide examples include dibenzyl polysulfide, various dinonyl polysulfides, various didodecyl polysulfides, various dibutyl polysulfides, various dioctyl polysulfides, diphenyl polysulfide and dicyclohexyl polysulfide.
  • thiadiazole compound a 1,3,4-thiadiazole compound, a 1,2,4-thiadiazole compound or a 1,4,5-thiadiazole compound represented by the following general formulas (X) may be preferably used:
  • R 31 and R 32 each represent a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms. and f and g each represent an integer of 0 to 8.
  • Examples of the thiadiazole compound include 2,5-bis(n-hexyldithio)-1,3,4-thiadiazole, 2,5-bis(n-octyldithio)-1,3,4-thiadiazole, 2,5-bis(n-nonyidithio)-1,3,4-thiadiazole, 2,5-bis-(1,1,3,3-tetramethylbutyldithio)-1,3,4-thiadiazole, 3,5-bis(n-hexyldithio)-1,2,4-thiadiazole, 3,6-bis(n-octyldithio)-1,2,4-thiadiazole, 3,5-bis(n-nonyidithio)-1,2,4-thiadiazole, 3,5-bis-(1,1,3,3-tetramethylbutyldithio)-1,2,4-thiadiazole, 4,5-bis(n-octyldithio)-1,2,3-thi
  • thiophosphorus acid ester examples include alkyl trithiophosphites, aryl or alkylaryl thiophosphates and zinc dilauryldithiophosphate. Among them, lauryl trithiophosphite and triphenyl thiophosphate are particularly preferable.
  • alkylthiocarbamoyl compound a compound represented by the following general formula (XI) may be used:
  • R 33 to R 36 each represent an alkyl group having 1 to 20 carbon atoms and h is an integer of 1 to 8.
  • alkylthiocarbamoyl compound examples include bis(dimethylthiocarbamoyl) monosulfide, bis(dibutylthiocarbamoyl) monosulfide, bis(dimethylthiocarbamoyl) disulfide, bis(dibutylthiocarbamoyl) disulfide, bis(diamylthiocarbamoyl) disulfide and bis(dioctylthiocarbamoyl) disulfide.
  • Examples of the thiocarbamate compound include a zinc dialkyl dithiocarbamate.
  • the thioterpene compound may be, for example, a reaction product of a phosphorus pentasulfide and pinene.
  • Examples of the dialkyl thiodipropionate compound include dilauryl thiodipropionate and distearyl thiodipropionate.
  • the thiadiazole compounds and benzyl sulfide are particularly preferable for reasons of good extreme pressure performance, friction characteristics and stability against thermal oxidation.
  • the friction modifiers may be used singly or in combination of two or more thereof.
  • the compounding amount of the friction modifier is generally 0.01 to 10% by mass, preferably 0.05 to 5% by mass, based on the total amount of the lubricant.
  • rust preventing agent examples include alkyl and alkenyl succinate derivatives such as dodecenyl succinate half esters, otcadecenyl succinic anhydride, and dodecenylsuccinamide; polyhydric alcohol partial esters such as sorbitan monooleate, glycerin monoolate and pentaerythritol monooleate; amines such as rosin amines, N-oleylsarcosine and alkylamines; and dialkyl phosphite amine salts.
  • alkyl and alkenyl succinate derivatives such as dodecenyl succinate half esters, otcadecenyl succinic anhydride, and dodecenylsuccinamide
  • polyhydric alcohol partial esters such as sorbitan monooleate, glycerin monoolate and pentaerythritol monooleate
  • amines such as rosin amines
  • the compounding amount of the rust preventing agent is preferably 0.01 to 5% by mass, particularly preferably 0.05 to 2% by mass, based on the total amount of the lubricant.
  • the metal deactivator there may be used, for example, benzotriazole compounds, thiadiazole compounds and gallic acid ester compounds.
  • the compounding amount of the metal deactivator is preferably in the range of 0.01 to 0.4% by mass, more preferably from 0.01 to 0.2% by mass, based on the total amount of the lubricant.
  • a liquid silicone is suited. Methylsilicone, fluorosilicone and polyacrylate may be used.
  • the compounding amount of the antifoaming agent is preferably in the range of 0.0005 to 0.01% by mass based on the total amount of the lubricant.
  • viscosity index improver examples include olefin copolymers, polyalkyl methacrylates, polyalkylstyrenes, polubutenes, ethylene-propylene copolymers, styrene-diene copolymers and styrene-maleic anhydride ester copolymers.
  • the compounding amount of the viscosity index improver is preferably 0.1 to 15% by mass, particularly preferably 0.5 to 7% by mass based on the total amount of the lubricant.
  • the lubricant for an oil retaining bearing according to the present invention preferably has a kinematic viscosity at 40° C. of 1 to 1,000 mm 2 /s.
  • a kinematic viscosity at 40° C. of 1 to 1,000 mm 2 /s.
  • the kinematic viscosity is more preferably 5 to 300 mm 2 /s.
  • the pour point is preferably ⁇ 10° C. or lower, more preferably ⁇ 20° C. or lower, still more preferably ⁇ 30° C. or lower, for reasons of reduced viscosity resistance at low temperatures.
  • the viscosity index is preferably at least 80, more preferably at least 100, still more preferably at least 120, for reasons of suppressing temperature dependency of the viscosity.
  • the 5% mass reduction 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.
  • the acid value is preferably 1 mgKOH/g or less, more preferably 0.5 mgKOH/g or less, still preferably 0.3 mgKOH/g or less, from the viewpoint of preventing corrosion of metal parts to which the lubricant of the present invention is applied.
  • the lubricant for an oil retaining bearing according to the present invention is used for retaining bearings made of a metallic porous body, a plastic porous body, a ceramic porous body, etc. and is particularly suited for a sintered, oil retaining bearing obtained by compacting and sintering metal powder.
  • Bearings conventionally used in spindle motors for such information equipments include rolling bearings, fluid dynamic bearings and sintered, oil retaining bearings. From these bearings a particular bearing best suited for the intended use is selected in consideration of the performance and cost.
  • Sintered, oil retaining bearings which have remarkably excellent production efficiency and can be produced on a large scale, have a merit that it can be put into the marketplace at a lower price as compared with rolling bearings or hydrodynamic bearings.
  • FIG. 1 is an enlarged, cross-sectional view illustrating an example of a spindle motor.
  • the reference numeral 1 designates a housing holder, 3 designates a bearing and 5 designates a motor shaft.
  • the housing holder 1 is mounted on a base B and has a cylindrical section 2 .
  • the cylindrical section 2 has an outer periphery provided with stacked cores 9 each having a coil 10 wound therearound.
  • the bearing 3 is produced by compacting and molding metal powder such as copper powder into a shape capable of being accommodated in the housing holder 1 , followed by sintering and impregnation with a lubricant for an oil retaining bearing according to the present invention.
  • the bearing 3 is provided with an open center 4 at a middle portion of its shaft hole and, therefore, is of a so-called open center and center free type.
  • the motor shaft 5 is supported at opposite end portions in the longitudinal direction of the bearing 3 .
  • the motor shaft 5 is made of a metal rod having such an outer diameter that the shaft is capable of being received in the bearing 3 .
  • a rotor 7 Integrally mounted, through a retaining member 6 , to a portion near an edge of the motor shaft 5 on an output side of the motor is a rotor 7 covering the laminate cores 9 and the coils 10 and provided with a magnet 8 on its inside periphery at a position facing each of the laminate cores 9 .
  • a hub configured to secure a rotation medium M of HDD is also integrally attached to an edge portion of the motor shaft 5 .
  • Means is provided to apply a lateral pressure in a specific direction to the motor shaft 5 received in the oil retaining bearing 3 formed of compacted and sintered metal powder so that one of the stacked cores 9 which are fixed at symmetrical positions relative to the motor shaft 5 is displaced by a distance t-t from the position indicated by the line “a” to the position indicated by the line “b”.
  • a side pressure is always applied to the motor shaft 5 in a specific direction (in the direction of the arrow Y).
  • the lubricant for an oil retaining bearing according to the present invention can contain at least 50% by mass of the ionic liquid as a base oil.
  • the lubricant has a low vapor pressure and has low flammability. Further, it has excellent heat resistance and can suppress the emanation of low volatile components and decomposed gases during use.
  • the lubricant can also contain the ionic liquid as an additive such as an antistatic agent. In such a case, it is possible to ground the static electricity generated by flow charging of the lubricant. It is without saying that such a function can be also obtained when the ionic fluid is used in the base oil.
  • the lubricant for an oil retaining bearing of the present invention can be utilized for various domestic motors and car motors.
  • Examples of the domestic motors for which the lubricant for an oil retaining bearing of the present invention can be utilized include floppy disk drive motors, CD drive motors, MO drive motors, DVD drive motors, hard disk drive motors, fan motors for coolers and blowers, polygon mirror drive motors, vibrating motors for mobile phones, stepping motors for optical lenses, etc.
  • Examples of the car motors for which the lubricant for an oil retaining bearing can be utilized include light retractable motors, water pump motors, wiper motors, head lamp cleaner motors, door lock actuator motors, antenna motors, power wind motors, power seat motors, mirror motors, telescopic motors, tilt steering motors, sun roof motors, electric curtain motors, radiator cooling fan motors, blower motors, air conditioner cooling fan motors, servo motors, automatic air conditioner internal air sensor motors, fuel leakage detecting sensor motors, air cleaner motors, car height adjuster motors, antilock brake motors, idle revolution controller motors, 4WD differential lock motors, odometer stepping motors, automatic drive motors, fuel stop motors, etc.
  • the lubricant for an oil retaining bearing is insoluble in a non-polar solvent such as gasoline, light oil or kerosene and, therefore, is suited for use in a motor bearing installed in a fuel tank, particularly in a motor for a sensor for detecting leakage of a fuel.
  • Kinematic viscosity was measured in accordance with “test method of kinematic viscosity for petroleum products” as specified in JIS K2283.
  • Viscosity index was measured in accordance with “test method of kinematic viscosity for petroleum products” as specified in JIS K2283.
  • Total acid number was measured by potentiometry in accordance with “test method of neutralization number for lubricants” as specified in JIS K2501.
  • Flash point was determined by the C.O.C method in accordance with JIS K2265.
  • the temperature at which the initial mass of a sample was reduced by 5%/min was determined using a differential thermal analyzer at a heating rate of 10° C. It can be said that the higher the 5% mass reduction temperature, the greater are the resistance to vaporization and the resistance to heat.
  • volume resistivity was measured in accordance with JIS C2102.
  • a load wear index was determined from the last non-seizure load (LNL) and the welding load (WL). The greater the load wear index, the better is the load resistance.
  • test was performed under a load of 196 N, at a revolution speed of 1,200 rpm and an oil temperature of 75° C. for a testing time of 60 minutes.
  • An average wear scar diameter was calculated by averaging wear scar diameters of three 0.5 inch balls.
  • Lubricants having compositions shown in Table 1 were prepared and tested for various properties. The results are shown in Table 1.
  • the lubricants of Examples 1 to 5 have a flash point higher than 300° C. notwithstanding the fact that it is low in viscosity. Further, the 5% mass reduction temperature is higher than 360° C., which shows that the lubricants have low volatility and excellent heat resistance. Moreover, the inventive lubricants have excellent load resistance and wear resistance.
  • the lubricant of Comparative Example 1 has a flash point of 236° C. which is lower than those of Examples 1 to 5. Further, the 5% mass reduction temperature is 269.3° C. which is much lower than those of Examples 1 to 5.
  • Lubricants having compositions shown in Tables 2-1 and 2-2 were prepared and tested for various properties. The results are shown in Tables 2-1 and 2-2.
  • Lubricants having compositions shown in Table 3 were prepared and tested for various properties. The results are shown in Table 3.
  • the lubricant for an oil retaining bearing according to the present invention which contains an ionic liquid as a base oil, has a low vapor pressure and has low flammability and, further, has excellent heat resistance and can suppress the emanation of low volatile components and decomposed gases during use.
  • the lubricant contains an ionic liquid as an additive, it is possible to ground the static electricity generated by flow charging of the lubricant.
  • the lubricant for an oil retaining bearing according to the present invention is used for retaining bearings made of a metallic porous body, a plastic porous body, a ceramic porous body, etc. and is particularly suited for a sintered, oil retaining bearing for spindle motors used in information equipments.
  • the lubricant for an oil retaining bearing is insoluble in a non-polar solvent such as gasoline, light oil or kerosene and, therefore, is suited for use in a motor bearing installed in a fuel tank, particularly in a motor for a sensor for detecting leakage of a fuel.

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US11/913,182 2005-07-15 2006-07-14 Lubricant for oil retaining bearing Abandoned US20090069204A1 (en)

Applications Claiming Priority (5)

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JP2005-207278 2005-07-15
JP2005207278 2005-07-15
JP2005334169A JP5074687B2 (ja) 2005-07-15 2005-11-18 含油軸受用潤滑剤
JP2005-334169 2005-11-18
PCT/JP2006/314040 WO2007010845A1 (fr) 2005-07-15 2006-07-14 Lubrifiant pour palier de retention d'huile

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US20090036334A1 (en) * 2007-08-03 2009-02-05 Peter Schwab Use of ionic liquids for the lubrication of components in wind power plants
EP2123741A1 (fr) * 2008-05-09 2009-11-25 Evonik Goldschmidt GmbH Additifs conducteurs liquides pour huiles hydrauliques non aqueuses
US20100105581A1 (en) * 2008-10-28 2010-04-29 Takanori Shiraishi Lubricating oil composition containing ionic liquid
US20100216675A1 (en) * 2009-02-20 2010-08-26 Jacob Joseph Habeeb Method for the control of hydroperoxide-induced oxidation in formulated lubricating oils by use of ionic liquids as additives
US20100227785A1 (en) * 2009-02-20 2010-09-09 Jacob Joseph Habeeb Method for the control of deposit formation in formulated lubricating oil by use of ionic liquids as additives
US20100227783A1 (en) * 2009-02-20 2010-09-09 Jacob Joseph Habeeb Method for reducing friction/wear of formulated lubricating oils by use of ionic liquids as anti-friction/anti-wear additives
WO2010112233A1 (fr) * 2009-04-01 2010-10-07 Friedrich-Alexander-Universität Erlangen-Nürnberg Lubrifiant pour moteur à combustion interne et moteur à combustion interne fonctionnant avec ce lubrifiant
WO2010072696A3 (fr) * 2008-12-22 2010-10-14 Basf Se Mélanges de liquides ioniques hydrophobes et hydrophiles et leur utilisation dans des compresseurs à anneau liquide
DE102010024431A1 (de) * 2010-06-21 2011-08-18 Siemens Aktiengesellschaft, 80333 Kabellose elektrische Verbindung
EP2087931A3 (fr) * 2008-02-05 2011-08-31 Evonik Goldschmidt GmbH Démoussage de fluides ioniques
CN102464498A (zh) * 2010-11-16 2012-05-23 中国科学院兰州化学物理研究所 离子液体二元复合纳米润滑膜的制备方法
US8252734B1 (en) 2009-12-09 2012-08-28 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Friction modifier using adherent metallic multilayered or mixed element layer conversion coatings
US8563487B1 (en) 2009-12-09 2013-10-22 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Friction modifier using adherent metallic multilayered or mixed element layer conversion coatings
CN103497806A (zh) * 2013-08-29 2014-01-08 中国石油化工股份有限公司 一种浸油轴承润滑脂组合物及制备方法
WO2014092953A1 (fr) * 2012-12-14 2014-06-19 Exxonmobil Research And Engineering Company Liquides ioniques jouant le rôle d'huiles lubrifiantes de base, additifs pour huile de base et fluides fonctionnels multifonctionnels
US20140212080A1 (en) * 2013-01-25 2014-07-31 Samsung Electro-Mechanics Japan Advanced Technolog Co., Ltd. Component for use in a bearing device and a method for forming a lubricant layer
US8946134B2 (en) 2009-02-27 2015-02-03 Ntn Corporation Grease composition, grease-packed bearing, universal joint for propeller shaft, lubricating oil composition, and oil-impregnated sintered bearing
DE102013112868A1 (de) 2013-11-21 2015-05-21 Friedrich-Alexander-Universität Erlangen-Nürnberg Verfahren zum Konservieren eines Maschinenelements und Verwendung einer ionischen Flüssigkeit
US20150232777A1 (en) * 2014-02-20 2015-08-20 Ut-Battelle, Llc Ionic liquids containing symmetric quaternary phosphonium cations and phosphorus-containing anions, and their use as lubricant additives
WO2015144106A1 (fr) 2014-03-26 2015-10-01 Schaeffler Technologies AG & Co. KG Procédés et système pour la surveillance du fonctionnement d'un élément lubrifié de machine
FR3028523A1 (fr) * 2014-11-19 2016-05-20 Nyco Procede pour ameliorer la resistance a la cokefaction d'une composition lubrifiante
US20170137736A1 (en) * 2014-06-19 2017-05-18 Dexerials Corporation Ionic liquid, lubricant, and magnetic recording medium
WO2018067902A1 (fr) * 2016-10-07 2018-04-12 Exxonmobil Research And Engineering Company Compositions d'huile lubrifiante pour un groupe motopropulseur de véhicule électrique
US20190027978A1 (en) * 2017-07-19 2019-01-24 Asia Vital Components Co., Ltd., Stator structure
CN111004669A (zh) * 2019-12-11 2020-04-14 中国科学院兰州化学物理研究所 一种离子液体木质素润滑组合物及其制备方法和应用
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DE102019104938A1 (de) * 2019-02-27 2020-08-27 Minebea Mitsumi Inc. Verwendung einer Additivmischung in einer Schmiermittelzusammensetzung für fluiddynamische Lagersysteme

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JP5194312B2 (ja) * 2007-07-30 2013-05-08 協同油脂株式会社 潤滑剤組成物
WO2009020038A1 (fr) * 2007-08-03 2009-02-12 Idemitsu Kosan Co., Ltd. Huile de base lubrifiante et composition lubrifiante
JP5273765B2 (ja) * 2007-09-14 2013-08-28 国立大学法人京都大学 溶融塩組成物及びその利用
JP5384005B2 (ja) * 2007-12-27 2014-01-08 サイデン化学株式会社 粘着剤組成物、粘着剤物品、光学用粘着剤組成物及び粘着方法
JP5180746B2 (ja) * 2008-09-05 2013-04-10 Ｎｔｎ株式会社 焼結含油軸受
JP2010168544A (ja) * 2008-12-26 2010-08-05 Nippon Synthetic Chem Ind Co Ltd:The 合成潤滑剤
JP5578949B2 (ja) * 2009-06-10 2014-08-27 日本合成化学工業株式会社 イオン液体組成物、及びその用途
EP2475753A1 (fr) * 2009-09-07 2012-07-18 Shell Internationale Research Maatschappij B.V. Compositions de lubrification
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JP5748485B2 (ja) * 2010-02-01 2015-07-15 日本合成化学工業株式会社 合成潤滑剤
US20120050916A1 (en) * 2010-08-31 2012-03-01 Seagate Technology Llc Hydrodynamic disc drive spindle motor having hydro bearing with lubricant
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DE102011108139A1 (de) * 2011-07-20 2013-01-24 Minebea Co., Ltd. Fluiddynamisches Lagersystem
JP2014098053A (ja) * 2012-11-13 2014-05-29 Nippon Synthetic Chem Ind Co Ltd:The 合成潤滑剤
JP5728710B2 (ja) * 2012-12-03 2015-06-03 サイデン化学株式会社 粘着剤組成物
JP6764424B2 (ja) * 2017-03-08 2020-09-30 日本電産株式会社 流体動圧軸受用潤滑油、流体動圧軸受、スピンドルモータ及びディスク駆動装置
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Cited By (40)

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EP2022840A3 (fr) * 2007-08-03 2009-11-25 Evonik Goldschmidt GmbH Utilisation de liquides ioniques pour le graissage de composants dans des éoliennes
US20090036334A1 (en) * 2007-08-03 2009-02-05 Peter Schwab Use of ionic liquids for the lubrication of components in wind power plants
EP2087931A3 (fr) * 2008-02-05 2011-08-31 Evonik Goldschmidt GmbH Démoussage de fluides ioniques
EP2123741A1 (fr) * 2008-05-09 2009-11-25 Evonik Goldschmidt GmbH Additifs conducteurs liquides pour huiles hydrauliques non aqueuses
US20100120640A1 (en) * 2008-05-09 2010-05-13 Peter Schwab Liquid conductivity additives for nonaqueous hydraulic oils
US20100105581A1 (en) * 2008-10-28 2010-04-29 Takanori Shiraishi Lubricating oil composition containing ionic liquid
WO2010072696A3 (fr) * 2008-12-22 2010-10-14 Basf Se Mélanges de liquides ioniques hydrophobes et hydrophiles et leur utilisation dans des compresseurs à anneau liquide
US8268760B2 (en) * 2009-02-20 2012-09-18 Exxonmobil Research And Engineering Company Method for reducing friction/wear of formulated lubricating oils by use of ionic liquids as anti-friction/anti-wear additives
US20100227783A1 (en) * 2009-02-20 2010-09-09 Jacob Joseph Habeeb Method for reducing friction/wear of formulated lubricating oils by use of ionic liquids as anti-friction/anti-wear additives
US20100227785A1 (en) * 2009-02-20 2010-09-09 Jacob Joseph Habeeb Method for the control of deposit formation in formulated lubricating oil by use of ionic liquids as additives
US8263536B2 (en) * 2009-02-20 2012-09-11 Exxonmobil Research And Engineering Company Method for the control of deposit formation in formulated lubricating oil by use of ionic liquids as additives
US20100216675A1 (en) * 2009-02-20 2010-08-26 Jacob Joseph Habeeb Method for the control of hydroperoxide-induced oxidation in formulated lubricating oils by use of ionic liquids as additives
US8278253B2 (en) * 2009-02-20 2012-10-02 Exxonmobil Research And Engineering Company Method for the control of hydroperoxide-induced oxidation in formulated lubricating oils by use of ionic liquids as additives
US8946134B2 (en) 2009-02-27 2015-02-03 Ntn Corporation Grease composition, grease-packed bearing, universal joint for propeller shaft, lubricating oil composition, and oil-impregnated sintered bearing
WO2010112233A1 (fr) * 2009-04-01 2010-10-07 Friedrich-Alexander-Universität Erlangen-Nürnberg Lubrifiant pour moteur à combustion interne et moteur à combustion interne fonctionnant avec ce lubrifiant
US8252734B1 (en) 2009-12-09 2012-08-28 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Friction modifier using adherent metallic multilayered or mixed element layer conversion coatings
US8563487B1 (en) 2009-12-09 2013-10-22 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Friction modifier using adherent metallic multilayered or mixed element layer conversion coatings
DE102010024431A1 (de) * 2010-06-21 2011-08-18 Siemens Aktiengesellschaft, 80333 Kabellose elektrische Verbindung
CN102464498A (zh) * 2010-11-16 2012-05-23 中国科学院兰州化学物理研究所 离子液体二元复合纳米润滑膜的制备方法
WO2014092953A1 (fr) * 2012-12-14 2014-06-19 Exxonmobil Research And Engineering Company Liquides ioniques jouant le rôle d'huiles lubrifiantes de base, additifs pour huile de base et fluides fonctionnels multifonctionnels
US20140212080A1 (en) * 2013-01-25 2014-07-31 Samsung Electro-Mechanics Japan Advanced Technolog Co., Ltd. Component for use in a bearing device and a method for forming a lubricant layer
CN103497806A (zh) * 2013-08-29 2014-01-08 中国石油化工股份有限公司 一种浸油轴承润滑脂组合物及制备方法
DE102013112868A1 (de) 2013-11-21 2015-05-21 Friedrich-Alexander-Universität Erlangen-Nürnberg Verfahren zum Konservieren eines Maschinenelements und Verwendung einer ionischen Flüssigkeit
US9957460B2 (en) * 2014-02-20 2018-05-01 Ut-Battelle, Llc Ionic liquids containing symmetric quaternary phosphonium cations and phosphorus-containing anions, and their use as lubricant additives
US20150232777A1 (en) * 2014-02-20 2015-08-20 Ut-Battelle, Llc Ionic liquids containing symmetric quaternary phosphonium cations and phosphorus-containing anions, and their use as lubricant additives
US10435642B2 (en) 2014-02-20 2019-10-08 Ut-Battelle, Llc. Ionic liquids containing symmetric quaternary phosphonium cations and phosphorus-containing anions, and their use as lubricant additives
WO2015144106A1 (fr) 2014-03-26 2015-10-01 Schaeffler Technologies AG & Co. KG Procédés et système pour la surveillance du fonctionnement d'un élément lubrifié de machine
US10481042B2 (en) 2014-03-26 2019-11-19 Schaeffler Technologies AG & Co. KG Method and system for monitoring the function of a lubricated machine element
US20170137736A1 (en) * 2014-06-19 2017-05-18 Dexerials Corporation Ionic liquid, lubricant, and magnetic recording medium
US9920272B2 (en) * 2014-06-19 2018-03-20 Dexerials Corporation Ionic liquid, lubricant, and magnetic recording medium
FR3028523A1 (fr) * 2014-11-19 2016-05-20 Nyco Procede pour ameliorer la resistance a la cokefaction d'une composition lubrifiante
CN107001976A (zh) * 2014-11-19 2017-08-01 Nyco公司 改进润滑组合物的抗结焦性的方法
WO2016079437A1 (fr) * 2014-11-19 2016-05-26 Nyco Procédé pour améliorer la résistance à la cokéfaction d'une composition lubrifiante
WO2018067902A1 (fr) * 2016-10-07 2018-04-12 Exxonmobil Research And Engineering Company Compositions d'huile lubrifiante pour un groupe motopropulseur de véhicule électrique
US20190027978A1 (en) * 2017-07-19 2019-01-24 Asia Vital Components Co., Ltd., Stator structure
US10432042B2 (en) * 2017-07-19 2019-10-01 Asia Vital Components Co., Ltd. Stator structure
CN111139117A (zh) * 2018-11-06 2020-05-12 协同油脂株式会社 防剥落剂和含有其的润滑剂组合物
EP3666860A1 (fr) * 2018-11-06 2020-06-17 Kyodo Yushi Co., Ltd. Agent anti-écaillage et composition de lubrifiant le comprenant
DE102019104938A1 (de) * 2019-02-27 2020-08-27 Minebea Mitsumi Inc. Verwendung einer Additivmischung in einer Schmiermittelzusammensetzung für fluiddynamische Lagersysteme
CN111004669A (zh) * 2019-12-11 2020-04-14 中国科学院兰州化学物理研究所 一种离子液体木质素润滑组合物及其制备方法和应用

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WO2007010845A1 (fr) 2007-01-25
KR20080028933A (ko) 2008-04-02

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