US20090069204A1 - Lubricant for oil retaining bearing - Google Patents
Lubricant for oil retaining bearing Download PDFInfo
- 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
- Authority
- 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
Links
- 0 [1*]C1([10*])C([8*])([9*])C([6*])([7*])C([4*])([5*])N1([2*])[3*].[1*]C1([12*])=C([2*])([3*])C([4*])([5*])=N([6*])([7*])C([8*])([9*])=C1([10*])[11*].[1*]C1([8*])N([2*])=C([3*])C([4*])([5*])C1([6*])[7*].[1*]C1=C([2*])C([3*])=N([4*])C([5*])=C1[6*].[1*]C1=C([6*])C([5*])=C([4*])N1([2*])[3*].[1*]N1=C([5*])C([4*])=N([3*])C1[2*].[1*][N+]([2*])([3*])[4*].[1*][P+]([2*])([3*])[4*].[1*][S+]([2*])[3*].[1*][SH]1C([2*])([3*])C([4*])([5*])C([6*])([7*])C1([8*])[9*] Chemical compound [1*]C1([10*])C([8*])([9*])C([6*])([7*])C([4*])([5*])N1([2*])[3*].[1*]C1([12*])=C([2*])([3*])C([4*])([5*])=N([6*])([7*])C([8*])([9*])=C1([10*])[11*].[1*]C1([8*])N([2*])=C([3*])C([4*])([5*])C1([6*])[7*].[1*]C1=C([2*])C([3*])=N([4*])C([5*])=C1[6*].[1*]C1=C([6*])C([5*])=C([4*])N1([2*])[3*].[1*]N1=C([5*])C([4*])=N([3*])C1[2*].[1*][N+]([2*])([3*])[4*].[1*][P+]([2*])([3*])[4*].[1*][S+]([2*])[3*].[1*][SH]1C([2*])([3*])C([4*])([5*])C([6*])([7*])C1([8*])[9*] 0.000 description 5
- OBNOIAWPHKEUNB-UHFFFAOYSA-N CCC[N+]1(C)CCCC1.CC[N+]1=CN(C)C=C1.O=S(=O)(F)[N-]S(=O)(=O)F.O=S(=O)(F)[N-]S(=O)(=O)F Chemical compound CCC[N+]1(C)CCCC1.CC[N+]1=CN(C)C=C1.O=S(=O)(F)[N-]S(=O)(=O)F.O=S(=O)(F)[N-]S(=O)(=O)F OBNOIAWPHKEUNB-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- 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.
Abstract
A lubricant for an oil retaining bearing containing 1 to 100% by mass of an ionic liquid. The lubricant 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 has antistatic property and is capable of grounding the static electricity generated by flow charging of the lubricant.
Description
- 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.
- In recent years, as bearings for spindle motors for driving, typically, magnetic disks and optical disks, there have been increasing cases in which sliding bearings, such as fluid bearings and sintered oil retaining bearings are used because of their silent operation and durability. With such a bearing, a shaft is separated by a lubricating oil film from an inside surface of the bearing. The bearing is characterized in that it can support a load applied to the shaft while reducing friction between the shaft and the bearing. Therefore, the performance of the bearing can be said to greatly depend upon the performance of the lubricating oil.
- The lubricating oil for such sliding bearings is required to have suitable viscosity, durability, antistatic property, etc. Among them, the viscosity is important because the electric power loss of a spindle motor and the bearing rigidity depend upon the viscosity. In recent years, there is a tendency to choose 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). In general, with a decrease of the viscosity of a lubricating oil, the amount of vaporized oil increases. Thus, a thoughtless use of a low viscosity lubricating oil might cause a loss of the lubricating oil, resulting in a lubrication failure in the bearing, and in the worst case, damage of the bearing. In consideration of this point, various proposals have been made to use specific base oils for the lubricating oil of bearings that can satisfy both low viscosity and low volatility. For example, 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 andPatent Document 5 propose the conjoint use of poly(α-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, andPatent Document 10 proposes the use of a specific diester of oxalic acid, malonic acid, succinic acid, etc. - Meanwhile, in the sliding bearings, a shaft is completely separated by a lubricating oil film from the bearing and is in non-contact therewith. Therefore, static electricity is apt to be generated by flow charging. Upon discharging, there is a fear that the important electronic parts (e.g., MR head of a hard disk drive) may become disordered. Therefore, it is necessary that the sliding bearing used in precision machines such as a magnetic disk apparatus should be grounded in order to remove the static electricity and to protect the electronic and magnetic parts. From this viewpoint, whilst the aforementioned conventional lubricating oils for bearings satisfy both low viscosity and low volatility, they still have a problem because they have a large volume resistivity and tend to generate static electricity.
- To cope with the above problem, a lubricating oil compounded with conductive microparticles of a metal or a metal oxide is reported (see, for example,
Patent Documents 11 and 12). However, 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. - As a lubricating oil free of such metal particles, there a proposal to add an organic metal salt such as a sulfonic acid, a phenate, or a salicylate (see Patent Document 13). However, the antistatic agent of such an organic metal salt cannot exhibit satisfactory antistatic property unless it is used in a large amount. In addition, the antistatic agent has a problem because it is deteriorated during long-term use and converted into an oil-insoluble inorganic salt (sludge).
- In the meanwhile, a series of ethylmethylimidazolium salts having different anions have been reported to have excellent heat stability and high ionic conductivity and to form a stable liquid even in the air atmosphere (see, for example, Non-Patent Document 1). Since then, organic ionic liquids composed of cations and anions have attracted an interest. Thus, studies are positively made on ionic liquids for various applications, such as electrolytic solutions for solar cells (see, for example, Patent Document 14), solvents for extraction and separation and reaction solvents, by utilizing their characteristics such as heat stability (low volatility and flame retardancy), high ionic density (high ionic conductivity) and low viscosity.
- 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.
- Further, 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.
- As an example of a lubricant using such an ionic fluid, a fluid bearing device is disclosed 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). In this technique, however, 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 9] Japanese Unexamined Patent Application Publication No. 2002-146381 (paragraph [0007])
- [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 15] Japanese Unexamined Patent Application Publication No. 2004-183868 [Non-Patent Document 1] “J. Chem. Soc. Chem. Commun.”, p965 (1992)
- Under the above circumstance, it is an object of the present invention to provide a lubricant for an oil retaining bearing 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 has antistatic property and is capable of grounding the static electricity generated by flow charging of the lubricant.
- 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.
- That is, the present invention provides:
- (1) 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 1×1010Ω·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): -
(Zp+)k.(Aq−)m (I) - (where Zp+ represents a cation, Aq− 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);
(7) 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;
(8) A lubricant for an oil retaining bearing as recited in any one of (1) to (5) above, in which the ionic liquid is of a zwitter ion type which the cation and the anion are bonded by a covalent bond;
(9) A lubricant for an oil retaining bearing as recited in any one of (6) to (8) above, in which the ionic liquid has a cation which a nitrogen atom is the ionic center;
(10) A lubricant for an oil retaining bearing as recited in any one of (1) to (9) above, which has a kinematic viscosity of 1 to 1,000 mm2/s at a temperature of 40° C.;
(11) A lubricant for an oil retaining bearing as recited in any one of (1) to (10) above, which is retained in the bearing of a metal porous body, a plastic porous body or a ceramic porous body;
(12) An oil retaining bearing using a lubricant for an oil retaining bearing as recited in any one of (1) to (11) above; and
(13) A motor unit including an oil retaining bearing as recited in (12) above. - According to the present invention, there can be provided 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. -
- 1: housing holder
- 2: cylindrical section
- 3: bearing
- 4: open center
- 5: motor shaft
- 6: retaining member
- 7: rotor
- 8: magnet
- 9: stacked core
- 10: coil
- 11: turn table
- B: base
- M: rotating medium
- 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.
- In the present invention 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)).
- As the ionic liquid (I), there may be used for example a compound represented by the following general formula (I):
-
(Zp+)k·(Aq−)m (1) - (where Zp+ represents a cation, Aq− 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).
- As the ionic liquid (I), a compound of the above general formula (I) in which p, k, q, and m are each 1, namely a compound of the following general formula (I-a):
-
Z+.A− (I-a) - (where Z+ represents a cation and A− represents an anion), is preferred.
- The aforementioned cation represented by Z+ is not specifically limited and any cation may be properly selected from the known cations used in the conventional ionic liquid. For example, cations represented the following general formulas may be preferably used:
- (where R1 to R12, 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 R1 to R12 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. Examples of the alkoxy group having 1 to 18 carbon atoms 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.
- In the present invention, cation groups having a nitrogen atom as the ionic center are preferred among the above-described cations.
- On the other hand, the aforementioned 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. For example, anions represented by the following formulas:
-
BF4 −,PF6 −,CnH(2n+1)OSO3 −,(CnF(2n+1−x)Hx)SO3 −,(CnF(2n+1−x)Hx)COO−,NO3 −, -
CH3SO3 −,(CN)2N−,HSO3 −,C6H5SO3 −,CH3 −(C6H4)SO3 −,I−,I3 −,F(HF)n −, -
[CnF(2n−1−x)Hx]Y1Oz)3C−,([CnF(2n+1−x)Hx]Y1Oz)2N− - (where Y1 represents a carbon atom or a sulfur atom, provided that when there are plurality such Y1 groups, they may be the same or different, and that the plural (CnF(2n+1−x)Hx)Y1O2 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 Y1 is a carbon atom and 0 to 4 when Y1 is a sulfur atom),
-
B(CmY2 (2m+1))4 −, P(CmY2 (2m+1))6 − - (where Y2 is a hydrogen atom or a fluorine atom, provided that when there are plural such Y2 groups, they may be the same or different; and m is an integer of 0 to 6), and anions of the following general formulas:
- (where R13 to R17, which may be the same or different, each represent a group selected from a hydrogen atom and (CnF(2n+1−x)Hx); and n and x have the same meanings as above)
- (where Rf1 represents a perfluoroalkyl group, Rf2 to Rf6 each independently represent a fluorine atom, a perfluoroalkyl group or a perfluorobenzyl group, p is 0 or 1, R18 and R19 each independently represent a halogen atom or a halogenated alkyl group, R20 to R22 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.) may be used.
- Among the above anions, preferred are A−, PF6 −, CnH(2n+1)OSO3 −, (CnF(2n+1−x)Hx)SO3 −, (CnF(2n+1−x)Hx)COO−, NO3 −,CH3SO3 −, (CN)2N−,HSO3 −, ([CnF(2n+1−x)Hx]Y1Oz)2N− (where Y1 represents a carbon atom or a sulfur atom, provided that when there are plural such Y1 groups, they 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 Y1 is a carbon atom and 0 to 4 when Y1 is a sulfur atom) and the anions of the above general formulas are preferred. Particularly preferred are CnH(2n+1)OSO3 −, (CnF(2n+1−x)Hx)SO3 −, (CnF(2n+1−x)Hx)COO−, NO3 −, CH3SO3 −, (CN)2N−, HSO3 − (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.
- As the ionic liquid (II) (zwitterionic liquid), there may be used the following compounds of the general formulas:
- (where R1 to R12, 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 R1′ to R12′ is —(CH2)n—SO3 − or —(CH2)n—COO− (where n is such an integer of 1 or more that the carbon number of the alkylene groups is 1 to 18).
- It is preferred that, in the cation of the ionic liquid (II), a nitrogen atom be the ionic center.
- In the present invention, the ionic liquids (I) and (II) may be incorporated into a lubricant as a base oil or as an additive. When used as the 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.
- When the ionic liquid is used as the base oil, 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.
- Specific examples of the 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, alkylammonium hexafluorophosphate, alkylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl(2-methoxyethyl)ammonium tetrafluoroborate, N,N-diethyl-N-methyl (2-methoxyethyl)ammonium hexafluorophosphate, and N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide. These ionic liquids may be used singly or in combination of two or more thereof.
- Above all, 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.
- Specific examples of the structure of bis(fluorosulfonyl)imides of the above-described ionic liquid (I) are given below.
- When two or more ionic liquids are used as a mixture, it is preferred that each of the ionic liquids be present in an amount of at least 10% by mass based on the mixture. As 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−.
- To be more specific, there may be mentioned a mixture of 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, a mixture of an alkylpyridinium hexafluorophosphate and an alkylpyridinium bis(trifluoromethanesulfonyl)imide, a mixture of an alkylammonium bis(trifluoromethanesulfonyl)imide and 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, a mixture of 1-butyl-3-methylimidazolium tetrafluoroborate and N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, a mixture of 1-butyl-3-methylimidazolium hexafluorophosphate and N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, a mixture of N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide and an alkylpyridinium tetrafluoroborate, and a mixture of N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide and an alkylpyridinium hexafluorophosphate.
- Above all, a mixture of 1-butyl-3-methylimidazolium tetrafluoroborate and N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, a mixture of 1-butyl-3-methylimidazolium hexafluorophosphate and N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, a mixture of N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide and alkylpyridinium tetrafluoroborate, and a mixture of N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide and alkylpyridinium hexafluorophosphate are preferred.
- When the ionic liquid (II) (zwitterionic liquid) is used as a base oil, 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 —(CH2)n—SO3 − or —(CH2)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).
- Specific examples of the ionic liquid (II) used as a base oil include 1-methyl-1,3-imidazolium N-butanesulfonate and N,N-diethyl-N-methylammonium N-butanesulfonate.
- When the ionic liquid (i) or (II) is used as an additive for the lubricant, the additive may function as an antistatic agent. In this case the content of the ionic liquid (i) and/or ionic liquid (II) is suitably 1% by mass or more. While the upper limit is not specifically restricted, it is preferred that the lubricant have a volume resistivity of 1×1010Ω·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 1×109Ω·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/dm3, more preferably at least 2 mol/dm3, still more preferably at least 3 mol/dm3. When the ion concentration is at least 1 mol/dm3, the object of the above use can be fully accomplished.
- In the lubricant for an oil retaining bearing according to the present invention, 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.
- In the present invention, 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.
- (1) As the antioxidant, there may be mentioned an amine type antioxidant, a phenolic antioxidant and a sulfur-containing antioxidant.
- Examples of the amine type antioxidant 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 α-naphthylamine, phenyl-α-naphthylamine, butylphenyl-α-naphthylamine, pentylphenyl-α-naphthylamine, hexylphenyl-α-naphthylamine, heptylphenyl-α-naphthylamine, octylphenyl-α-naphthylamine and nonylphenyl-α-naphthylamine. Above all, the dialkyl diphenylamine type antioxidants are particularly preferable.
- Examples of the phenolic antioxidant 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).
- Examples of the sulfur-containing antioxidant 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.
- (2) 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.
- These 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.
- (3) 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.
- Examples of the phosphoric esters include phosphoric esters, acid phosphoric esters, phosphorous acid esters and acid phosphorous acid esters which are represented by general formulas (II) to (VI) below.
- In the above general formulas (II) to (VI), R23 to R25, 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, butylphenyl diphenyl phosphate, dibutylphenyl phenyl phosphate, tributylphenyl phosphate, trihexyl phosphate, tri(2-ethylhexyl) phosphate, tridecyl phosphate, trilauryl phosphate, trimyristyl phosphate, tripalmityl phosphate, tristearyl phosphate and trioleyl phosphate.
- 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. Among the above phosphoric esters, 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):
-
R26 pNH3−p (VII) - (where R26 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 R26 groups, they may be the same or different.)
- The alkyl or alkenyl group having 3 to 30 carbon atoms represented by R26 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. Examples of the disubstituted amine include dibutylamine, dipentylamine, dihexylamine, dicyclohexylamine, dioctylamine, dilaurylamine, distearylamine, dioleylamine, dibenzylamine, stearylmonoethanolamine, decylmonoethanolamine, hexylmonopropanolamine, benzylmonoethanolamine, phenylmonoethanolamine and tolylmonopropanolamine. Examples of the trisubstituted amine 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. Examples of 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.
- As the olefin sulfide there may be mentioned a compound represented by the following general formula (VIII):
-
R27—Sq—R28 (VIII) - (where R27 represents an alkenyl group having 2 to 15 carbon atoms, R28 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. Preferred olefins are propylene, isobutene and diisobutene.
- The dihydrocarbyl polysulfide may be a compound represented by the following general formula (IX):
-
R29Sr—R30 (IX) - (where R29 and R30, 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.) When each of R29 and R30 is an alkyl group, such a compound is called an alkyl sulfide.
- Examples of R29 and R30 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.
- Examples of the dihydrocarbyl polysulfide include dibenzyl polysulfide, various dinonyl polysulfides, various didodecyl polysulfides, various dibutyl polysulfides, various dioctyl polysulfides, diphenyl polysulfide and dicyclohexyl polysulfide.
- As the 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:
- (where R31 and R32 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-thiadiazole, 4,5-bis(n-nonyldithio)-1,2,3-thiadiazole and 4,5-bis-(1,1,3,3-tetramethylbutyldithio)-1,2,3-thiadiazole.
- Examples of the thiophosphorus acid ester include alkyl trithiophosphites, aryl or alkylaryl thiophosphates and zinc dilauryldithiophosphate. Among them, lauryl trithiophosphite and triphenyl thiophosphate are particularly preferable.
- As the alkylthiocarbamoyl compound, a compound represented by the following general formula (XI) may be used:
- (where R33 to R36 each represent an alkyl group having 1 to 20 carbon atoms and h is an integer of 1 to 8.)
- Examples of the alkylthiocarbamoyl compound 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. Among the above sulfur-containing extreme pressure agents, 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.
- (4) Examples of the rust preventing agent 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. These rust preventing agents may be used alone or in combination of two or more thereof.
- 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.
- (5) As 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.
- (6) As the antifoaming agent, 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.
- (7) Examples of the viscosity index improver 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 mm2/s. When the kinematic viscosity is within the above range, an evaporation loss and a power loss due to viscosity resistance can be suppressed. The kinematic viscosity is more preferably 5 to 300 mm2/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.
- Operation accuracy of spindle motors used in information equipments (particularly CD and DVD) has been increased year by year. 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.
- However, for use in an HDD spindle motor which is a high precision and high quality recording instrument requiring much higher rotation accuracy and higher credibility, the sintered, oil retaining bearings have a problem because there is a certain clearance relative to the rotational axis and, hence, a rotational variation is apt to occur.
- To solve this problem, a specific mechanism has been developed in which a prescribed-directional lateral pressure is applied to a sintered, oil retaining bearing so as to reduce the deflection of the rotational axis of the motor while retaining inherent characteristics of the sintered, oil retaining bearing (Japanese Unexamined Patent Application Publication No. 2001-295844). The lubricant of the present invention is suitably used in such a mechanism.
- The above-described mechanism will be next described with reference to the accompanying drawing.
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 acylindrical section 2. Thecylindrical section 2 has an outer periphery provided withstacked cores 9 each having acoil 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. Thebearing 3 is provided with anopen center 4 at a middle portion of its shaft hole and, therefore, is of a so-called open center and center free type. Themotor shaft 5 is supported at opposite end portions in the longitudinal direction of thebearing 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 thebearing 3. Integrally mounted, through a retainingmember 6, to a portion near an edge of themotor shaft 5 on an output side of the motor is arotor 7 covering thelaminate cores 9 and thecoils 10 and provided with amagnet 8 on its inside periphery at a position facing each of thelaminate cores 9. A hub configured to secure a rotation medium M of HDD is also integrally attached to an edge portion of themotor shaft 5. - Means is provided to apply a lateral pressure in a specific direction to the
motor shaft 5 received in theoil retaining bearing 3 formed of compacted and sintered metal powder so that one of thestacked cores 9 which are fixed at symmetrical positions relative to themotor 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”. As a consequence of the inclination of thestacked cores 9, it is possible to always urge therotor 7 rotating at a high speed in the direction indicated by the arrow P. Therefore, a side pressure is always applied to themotor shaft 5 in a specific direction (in the direction of the arrow Y). - By applying a side pressure in the specific direction to the motor shaft, the deflection of the shaft relative to the oil retaining bearing formed by compacting and sintering metal powder.
- 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. In such a case, 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.
- The present invention will be next described in more detail by way of examples but is not limited to these examples in any way. Various properties of lubricants were measured by the following methods.
- 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.
- Pour point was measured in accordance with JIS K2269.
- 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.
- In accordance with ASTM D 2783, test was performed at a revolution speed of 1,800 rpm at room temperature. A load wear index (LWI) 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.
- In accordance with ASTM D 2783, 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.
-
TABLE 1 Examples Comparative 1 2 3 4 5 6 Ex. 1 Lubricant Base oil Ionic liquid 1 100 — — — — — — (mass %) Ionic liquid 2 — 100 99 99 — — — Ionic liquid 3 — — — — 96.9 — — Ionic liquid 4 — — — — — 100 — Polyol ester — — — — — — 100 Additive TCP — — 1 — 1 — — DBDS — — — 1 — — — n-Octylamine — — — — 2 — — Benzotriazole — — — — 0.1 — — Evaluation 40° C. Kinematic viscosity (mm2/s) 22.41 27.10 27.14 27.10 13.23 26.69 19.50 Viscosity index 160 114 114 114 189 155 132 Pour point (° C.) −20.0 −30.0 −30.0 −30.0 −22.5 −50> −45.0 Total acid number (mgKOH/g) 0.29 0.30 0.32 0.30 0.01 0.01 0.05 Flash point (C.O.C) 300< 300< 300< 300< 300< 300< 236 5% Mass reduction temperature (° C.) 411.3 363.8 362.5 361.1 393 387 269.3 Load resistance test (LWI) 1512 1526 1519 1533 1575 1575 139 Wear resistance test (mm) 0.43 0.52 0.4 0.37 0.38 0.53 0.57 Compatibility with gasoline insoluble insoluble insoluble insoluble insoluble insoluble soluble Compatibility with light oil insoluble insoluble insoluble insoluble insoluble insoluble soluble Compatibility with kerosene insoluble insoluble insoluble insoluble insoluble insoluble soluble -
- Ionic liquid 1: Butylpyridinium bis(trifluoromethanesulfonyl)imide
- Ionic liquid 2: N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide
- Polyol ester: Ester of trimethylolpropane with fatty acids having 8 and 10 carbon atoms
- Ionic liquid 3: 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide
- Ionic liquid 4: 1-Hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide
- TCP: Tricresyl phosphate
- DBDS: Dibenzyldisulfide
- It is seen from Table 1 that 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.
- In contrast, 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.
-
TABLE 2-1 Examples 7 1 8 9 10 Lubricant Base oil Ionic liquid 5100 — 90 80 60 (mass %) Ionic liquid 1 100 10 20 40 Evaluation 40° C. Kinematic viscosity (mm2/s) 85.29 22.41 65.39 45.73 44.46 Viscosity index 123 160 — 162 130 Pour point (° C.) −7.5 −20.0 −27.5 −37.5 −35.0 Total acid number (mgKOH/g) 0.06 0.29 0.08 0.11 0.15 Flash point (C.O.C) 300< 300< 300< 300< 300< 5% Mass reduction temperature (° C.) 372.0 411.3 373.2 380.2 397.6 Load resistance test (LWI) 1522 1512 1511 1523 1517 Wear resistance test (mm) 0.5 0.43 0.45 0.46 0.42 -
TABLE 2-2 Examples 11 12 13 14 Lubricant Base oil Ionic liquid 550 40 20 10 (mass %) Ionic liquid 1 50 60 80 90 Evaluation 40° C. Kinematic viscosity (mm2/s) 38.65 35.31 35.73 24.63 Viscosity index 143 160 185 162 Pour point (° C.) −45.0 −37.5 −40.0 −27.5 Total acid number (mgKOH/g) 0.18 0.20 0.24 0.27 Flash point (C.O.C) 300< 300< 300< 300< 5% Mass reduction temperature 401.4 406.1 407.0 408.9 (° C.) Load resistance test (LWI) 1523 1531 1527 1533 Wear resistance test (mm) 0.44 0.43 0.42 0.44 -
- Ionic liquid 5: N,N-diethyl-N-methyl(2-methoxyethyl)ammonium tetrafluoroborate
- Ionic liquid 1: the same as given in the remarks of Table 1
- The results shown in Tables 2-1 and 2-2 indicate that the use of two kinds of ionic liquids in combination can improve the viscosity index and pour point.
- Lubricants having compositions shown in Table 3 were prepared and tested for various properties. The results are shown in Table 3.
-
TABLE 3 Comparative Examples Example 15 16 17 2 Lubricant Base oil Ether-based base oil 95 90 80 100 (mass %) Additive Ionic liquid 25 10 20 — Evaluation 40° C. Kinematic viscosity (mm2/s) 8.588 8.856 9.471 8.340 Viscosity index 129 131 134 129 Pour point (° C.) −45 −45 −42.5 −45 Total acid number (mgKOH/g) 0.02 0.04 0.06 0.01 Flash point (C.O.C) 212 223 241 210 5% Mass reduction temperature (° C.) 208 215 228 208 Load resistance test (LWI) 230 254 294 46 Wear resistance test (mm) 0.58 0.56 0.55 0.78 Volume resistivity (×1010 Ω · cm) 0.9 0.7 0.2 8 - Ether-based base oil: 2-octyldodecyl decyl ether
Ionic liquid 2: the same as given in the remarks of Table 1 - The results shown in Table 3 indicate that the incorporation of the ionic liquid as an additive can reduce the volume resistivity of the lubricant and can impart antistatic property thereto.
- 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.
- When 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.
- Further, 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.
Claims (13)
1. A lubricant for an oil retaining bearing comprising 1 to 100% by mass of an ionic liquid.
2. A lubricant for an oil retaining bearing as defined in claim 1 , comprising a base oil which contains 50 to 100% by mass of the ionic liquid.
3. A lubricant for an oil retaining bearing as defined in claim 2 , wherein 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 defined in claim 1 , wherein the ionic liquid is contained as an antistatic agent.
5. A lubricant for an oil retaining bearing as defined in any one of claims 1 to 4 , which has a volume resistivity at 25° C. of 1×1010Ω·cm or less.
6. A lubricant for an oil retaining bearing as defined in any one of claims 1 to 5 , wherein the ionic liquid is a compound represented by the following general formula (I):
(Zp+)k.(Aq−)m (I)
(Zp+)k.(Aq−)m (I)
(where Zp+ represents a cation, Aq− 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.)
7. A lubricant for an oil retaining bearing as defined in claim 6 , wherein p, q, k and m in the general formula (I) are each 1.
8. A lubricant for an oil retaining bearing as defined in any one of claims 1 to 5 , wherein the ionic liquid is of a zwitter ion type in which the cation and the anion are bonded by a covalent bond.
9. A lubricant for an oil retaining bearing as defined in any one of claims 6 to 8 , wherein the ionic liquid has a cation in which a nitrogen atom is the ionic center.
10. A lubricant for an oil retaining bearing as defined in any one of claims 1 to 9 , which has a kinematic viscosity of 1 to 1,000 mm2/s at a temperature of 40° C.
11. A lubricant for an oil retaining bearing as defined in any one of claims 1 to 10 , which is retained in the bearing of a metal porous body, a plastic porous body or a ceramic porous body.
12. An oil retaining bearing using a lubricant for an oil retaining bearing as defined in any one of claims 1 to 11 .
13. A motor unit comprising an oil retaining bearing as defined in claim 12 .
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2005-207278 | 2005-07-15 | ||
JP2005207278 | 2005-07-15 | ||
JP2005-334169 | 2005-11-18 | ||
JP2005334169A JP5074687B2 (en) | 2005-07-15 | 2005-11-18 | Oil-impregnated bearing lubricant |
PCT/JP2006/314040 WO2007010845A1 (en) | 2005-07-15 | 2006-07-14 | Lubricant for oil retaining bearing |
Publications (1)
Publication Number | Publication Date |
---|---|
US20090069204A1 true US20090069204A1 (en) | 2009-03-12 |
Family
ID=37668726
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/913,182 Abandoned US20090069204A1 (en) | 2005-07-15 | 2006-07-14 | Lubricant for oil retaining bearing |
Country Status (5)
Country | Link |
---|---|
US (1) | US20090069204A1 (en) |
JP (1) | JP5074687B2 (en) |
KR (1) | KR20080028933A (en) |
CN (1) | CN101223263B (en) |
WO (1) | WO2007010845A1 (en) |
Cited By (27)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090036334A1 (en) * | 2007-08-03 | 2009-02-05 | Peter Schwab | Use of ionic liquids for the lubrication of components in wind power plants |
EP2123741A1 (en) * | 2008-05-09 | 2009-11-25 | Evonik Goldschmidt GmbH | Liquid conductive additive for non-aqueous hydraulic oils |
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 |
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 |
WO2010112233A1 (en) * | 2009-04-01 | 2010-10-07 | Friedrich-Alexander-Universität Erlangen-Nürnberg | Lubricant for an internal combustion engine and internal combustion engine operated with the same |
WO2010072696A3 (en) * | 2008-12-22 | 2010-10-14 | Basf Se | Mixtures of hydrophobic and hydrophilic ionic liquids and use thereof in liquid ring compressors |
DE102010024431A1 (en) * | 2010-06-21 | 2011-08-18 | Siemens Aktiengesellschaft, 80333 | Device for electrical conductive connection between e.g. slide bearing and shaft of electric motor, has recesses engaged with slats, and shaft and slide bearing forming circulating gap, which is filled with ionic liquid |
EP2087931A3 (en) * | 2008-02-05 | 2011-08-31 | Evonik Goldschmidt GmbH | Defoaming of ionic fluids |
CN102464498A (en) * | 2010-11-16 | 2012-05-23 | 中国科学院兰州化学物理研究所 | Preparation method of ionic liquid binary composite nano lubricating film |
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 (en) * | 2013-08-29 | 2014-01-08 | 中国石油化工股份有限公司 | Oil immersion bearing grease composition and preparation method |
WO2014092953A1 (en) * | 2012-12-14 | 2014-06-19 | Exxonmobil Research And Engineering Company | Ionic liquids as lubricating oil base stocks, cobase stocks and multifunctional functional fluids |
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 (en) | 2013-11-21 | 2015-05-21 | Friedrich-Alexander-Universität Erlangen-Nürnberg | Method of preserving a machine element and using an ionic liquid |
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 (en) | 2014-03-26 | 2015-10-01 | Schaeffler Technologies AG & Co. KG | Method and system for monitoring the function of a lubricated machine element |
FR3028523A1 (en) * | 2014-11-19 | 2016-05-20 | Nyco | PROCESS FOR IMPROVING THE COKEFACTION RESISTANCE OF A LUBRICATING COMPOSITION |
US20170137736A1 (en) * | 2014-06-19 | 2017-05-18 | Dexerials Corporation | Ionic liquid, lubricant, and magnetic recording medium |
WO2018067902A1 (en) * | 2016-10-07 | 2018-04-12 | Exxonmobil Research And Engineering Company | Lubricating oil compositions for electric vehicle powertrains |
US20190027978A1 (en) * | 2017-07-19 | 2019-01-24 | Asia Vital Components Co., Ltd., | Stator structure |
CN111004669A (en) * | 2019-12-11 | 2020-04-14 | 中国科学院兰州化学物理研究所 | Ionic liquid lignin lubricating composition and preparation method and application thereof |
CN111139117A (en) * | 2018-11-06 | 2020-05-12 | 协同油脂株式会社 | Anti-flaking agent and lubricant composition containing same |
DE102019104938A1 (en) * | 2019-02-27 | 2020-08-27 | Minebea Mitsumi Inc. | Use of an additive mixture in a lubricant composition for fluid dynamic bearing systems |
Families Citing this family (24)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2006105207A (en) * | 2004-10-01 | 2006-04-20 | Matsushita Electric Ind Co Ltd | Fluid bearing device, spindle motor using the same, and disk driving device using the spindle motor |
JP2008266557A (en) * | 2007-03-26 | 2008-11-06 | Sanyo Chem Ind Ltd | Lubricant |
JP5274880B2 (en) * | 2007-04-23 | 2013-08-28 | 日本合成化学工業株式会社 | Ionic liquid composition and synthetic lubricating oil using the same |
JP2009007565A (en) * | 2007-05-29 | 2009-01-15 | Sanyo Chem Ind Ltd | Lubricating oil |
JP5194312B2 (en) * | 2007-07-30 | 2013-05-08 | 協同油脂株式会社 | Lubricant composition |
WO2009020038A1 (en) * | 2007-08-03 | 2009-02-12 | Idemitsu Kosan Co., Ltd. | Lubricant base oil and lubricant composition |
JP5273765B2 (en) * | 2007-09-14 | 2013-08-28 | 国立大学法人京都大学 | Molten salt composition and use thereof |
JP5384005B2 (en) * | 2007-12-27 | 2014-01-08 | サイデン化学株式会社 | Adhesive composition, adhesive article, optical adhesive composition and adhesive method |
JP5180746B2 (en) * | 2008-09-05 | 2013-04-10 | Ntn株式会社 | Sintered oil-impregnated bearing |
JP2010168544A (en) * | 2008-12-26 | 2010-08-05 | Nippon Synthetic Chem Ind Co Ltd:The | Synthetic lubricant |
JP5578949B2 (en) * | 2009-06-10 | 2014-08-27 | 日本合成化学工業株式会社 | Ionic liquid composition and use thereof |
WO2011026990A1 (en) * | 2009-09-07 | 2011-03-10 | Shell Internationale Research Maatschappij B.V. | Lubricating compositions |
CN102025212B (en) * | 2009-09-18 | 2014-03-12 | 德昌电机(深圳)有限公司 | Direct current brushless motor for heating ventilating and air conditioning system |
JP5748485B2 (en) * | 2010-02-01 | 2015-07-15 | 日本合成化学工業株式会社 | Synthetic lubricant |
US20120050916A1 (en) * | 2010-08-31 | 2012-03-01 | Seagate Technology Llc | Hydrodynamic disc drive spindle motor having hydro bearing with lubricant |
CN102562803B (en) * | 2010-12-31 | 2015-04-15 | 上海思考电子有限公司 | Manufacturing method of oil bearing |
DE102011108139A1 (en) * | 2011-07-20 | 2013-01-24 | Minebea Co., Ltd. | Fluid-dynamic bearing system for rotatably supporting spindle motor, has bearing sleeves separated from each other by bearing gap filled with bearing fluid, where gap is sealed by sealing gap that is partially filled with ionic liquid |
JP2014098053A (en) * | 2012-11-13 | 2014-05-29 | Nippon Synthetic Chem Ind Co Ltd:The | Synthetic lubricant |
JP5728710B2 (en) * | 2012-12-03 | 2015-06-03 | サイデン化学株式会社 | Adhesive composition |
JP6764424B2 (en) * | 2017-03-08 | 2020-09-30 | 日本電産株式会社 | Lubricating oil for fluid dynamic bearings, fluid dynamic bearings, spindle motors and disk drives |
CN109097171B (en) * | 2018-09-25 | 2021-05-28 | 中国石油化工股份有限公司 | Oil film bearing oil composition and preparation method thereof |
CN112778204A (en) * | 2021-01-13 | 2021-05-11 | 宝鸡文理学院 | Ionic liquid containing metal anions, and preparation method and application thereof |
CN113403131B (en) * | 2021-06-16 | 2022-06-10 | 中国科学院兰州化学物理研究所 | Super-lubricating water-based cutting fluid |
WO2023090432A1 (en) * | 2021-11-19 | 2023-05-25 | ミネベアミツミ株式会社 | Fluid dynamic bearing, spindle motor, and disk drive device |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5827602A (en) * | 1995-06-30 | 1998-10-27 | Covalent Associates Incorporated | Hydrophobic ionic liquids |
US20020015884A1 (en) * | 2000-06-09 | 2002-02-07 | Merck Patent Gmbh | Ionic liquids II |
US6423126B1 (en) * | 1999-10-08 | 2002-07-23 | Minebea Co., Ltd. | Less outgas generating anticorrosive composition for HDD |
US20040035293A1 (en) * | 2002-04-05 | 2004-02-26 | Davis James Hillard | Functionalized ionic liquids, and methods of use thereof |
US20040179758A1 (en) * | 2002-12-06 | 2004-09-16 | Matsushita Electric Industrial Co., Ltd. | Fluid dynamic bearing and magnetic disk apparatus |
US20060199747A1 (en) * | 2003-04-02 | 2006-09-07 | Idemitsu Kosan Co., Ltd. | Conductive lubricant composition |
US20070027038A1 (en) * | 2003-10-10 | 2007-02-01 | Idemitsu Losan Co., Ltd. | Lubricating oil |
US7297289B2 (en) * | 2001-03-26 | 2007-11-20 | Nisshinbo Industries, Inc. | Ionic liquids, electrolyte salts for storage device, electrolytic solution for storage device, electric double layer capacitor, and secondary battery |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3943381B2 (en) * | 2001-12-05 | 2007-07-11 | 日本電産株式会社 | Bearing device and motor equipped with the same |
JP2005089667A (en) * | 2003-09-19 | 2005-04-07 | Sanko Kagaku Kogyo Kk | Antistatic lubricant oil composition |
JP2005147394A (en) * | 2003-10-23 | 2005-06-09 | Sankyo Seiki Mfg Co Ltd | Dynamic-pressure bearing device and disc driving device |
JP2005147329A (en) * | 2003-11-18 | 2005-06-09 | Ntn Corp | Bearing device for wind power generator |
JP4327038B2 (en) * | 2004-07-21 | 2009-09-09 | Ntn株式会社 | Spindle motor |
JP2007039653A (en) * | 2005-06-28 | 2007-02-15 | Sanyo Chem Ind Ltd | Liquid lubricant |
-
2005
- 2005-11-18 JP JP2005334169A patent/JP5074687B2/en not_active Expired - Fee Related
-
2006
- 2006-07-14 US US11/913,182 patent/US20090069204A1/en not_active Abandoned
- 2006-07-14 WO PCT/JP2006/314040 patent/WO2007010845A1/en active Application Filing
- 2006-07-14 CN CN2006800257118A patent/CN101223263B/en not_active Expired - Fee Related
- 2006-07-14 KR KR1020087001014A patent/KR20080028933A/en not_active Application Discontinuation
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5827602A (en) * | 1995-06-30 | 1998-10-27 | Covalent Associates Incorporated | Hydrophobic ionic liquids |
US6423126B1 (en) * | 1999-10-08 | 2002-07-23 | Minebea Co., Ltd. | Less outgas generating anticorrosive composition for HDD |
US20020015884A1 (en) * | 2000-06-09 | 2002-02-07 | Merck Patent Gmbh | Ionic liquids II |
US7297289B2 (en) * | 2001-03-26 | 2007-11-20 | Nisshinbo Industries, Inc. | Ionic liquids, electrolyte salts for storage device, electrolytic solution for storage device, electric double layer capacitor, and secondary battery |
US20040035293A1 (en) * | 2002-04-05 | 2004-02-26 | Davis James Hillard | Functionalized ionic liquids, and methods of use thereof |
US20040179758A1 (en) * | 2002-12-06 | 2004-09-16 | Matsushita Electric Industrial Co., Ltd. | Fluid dynamic bearing and magnetic disk apparatus |
US20060199747A1 (en) * | 2003-04-02 | 2006-09-07 | Idemitsu Kosan Co., Ltd. | Conductive lubricant composition |
US20070027038A1 (en) * | 2003-10-10 | 2007-02-01 | Idemitsu Losan Co., Ltd. | Lubricating oil |
Cited By (40)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2022840A3 (en) * | 2007-08-03 | 2009-11-25 | Evonik Goldschmidt GmbH | Use of ionic liquids for lubrication of components in wind farms |
US20090036334A1 (en) * | 2007-08-03 | 2009-02-05 | Peter Schwab | Use of ionic liquids for the lubrication of components in wind power plants |
EP2087931A3 (en) * | 2008-02-05 | 2011-08-31 | Evonik Goldschmidt GmbH | Defoaming of ionic fluids |
EP2123741A1 (en) * | 2008-05-09 | 2009-11-25 | Evonik Goldschmidt GmbH | Liquid conductive additive for non-aqueous hydraulic oils |
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 (en) * | 2008-12-22 | 2010-10-14 | Basf Se | Mixtures of hydrophobic and hydrophilic ionic liquids and use thereof in liquid ring compressors |
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 |
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 |
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 (en) * | 2009-04-01 | 2010-10-07 | Friedrich-Alexander-Universität Erlangen-Nürnberg | Lubricant for an internal combustion engine and internal combustion engine operated with the same |
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 (en) * | 2010-06-21 | 2011-08-18 | Siemens Aktiengesellschaft, 80333 | Device for electrical conductive connection between e.g. slide bearing and shaft of electric motor, has recesses engaged with slats, and shaft and slide bearing forming circulating gap, which is filled with ionic liquid |
CN102464498A (en) * | 2010-11-16 | 2012-05-23 | 中国科学院兰州化学物理研究所 | Preparation method of ionic liquid binary composite nano lubricating film |
WO2014092953A1 (en) * | 2012-12-14 | 2014-06-19 | Exxonmobil Research And Engineering Company | Ionic liquids as lubricating oil base stocks, cobase stocks and multifunctional functional fluids |
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 (en) * | 2013-08-29 | 2014-01-08 | 中国石油化工股份有限公司 | Oil immersion bearing grease composition and preparation method |
DE102013112868A1 (en) | 2013-11-21 | 2015-05-21 | Friedrich-Alexander-Universität Erlangen-Nürnberg | Method of preserving a machine element and using an ionic liquid |
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 (en) | 2014-03-26 | 2015-10-01 | Schaeffler Technologies AG & Co. KG | Method and system for monitoring the function of a lubricated machine element |
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 (en) * | 2014-11-19 | 2016-05-20 | Nyco | PROCESS FOR IMPROVING THE COKEFACTION RESISTANCE OF A LUBRICATING COMPOSITION |
CN107001976A (en) * | 2014-11-19 | 2017-08-01 | Nyco公司 | The method for improving the anti-coking of lubricating composition |
WO2016079437A1 (en) * | 2014-11-19 | 2016-05-26 | Nyco | Method for improving the coking resistance of a lubricating composition |
WO2018067902A1 (en) * | 2016-10-07 | 2018-04-12 | Exxonmobil Research And Engineering Company | Lubricating oil compositions for electric vehicle powertrains |
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 (en) * | 2018-11-06 | 2020-05-12 | 协同油脂株式会社 | Anti-flaking agent and lubricant composition containing same |
EP3666860A1 (en) * | 2018-11-06 | 2020-06-17 | Kyodo Yushi Co., Ltd. | Anti-flaking agent and lubricant composition comprising the same |
DE102019104938A1 (en) * | 2019-02-27 | 2020-08-27 | Minebea Mitsumi Inc. | Use of an additive mixture in a lubricant composition for fluid dynamic bearing systems |
CN111004669A (en) * | 2019-12-11 | 2020-04-14 | 中国科学院兰州化学物理研究所 | Ionic liquid lignin lubricating composition and preparation method and application thereof |
Also Published As
Publication number | Publication date |
---|---|
CN101223263A (en) | 2008-07-16 |
JP2007046030A (en) | 2007-02-22 |
KR20080028933A (en) | 2008-04-02 |
WO2007010845A1 (en) | 2007-01-25 |
JP5074687B2 (en) | 2012-11-14 |
CN101223263B (en) | 2012-08-15 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US20090069204A1 (en) | Lubricant for oil retaining bearing | |
KR101302940B1 (en) | Conductive lubricant composition | |
JP5202830B2 (en) | Lubricating oil for fluid bearing, fluid bearing using the same, and lubrication method for fluid bearing | |
US10077229B2 (en) | Ether-containing monoester compound and use thereof | |
US20070281873A1 (en) | Lubricant Composition for Fluid Dynamic Bearing | |
JP2013501135A (en) | Fluid dynamic pressure disk drive spindle motor having a hydro-bearing with a lubricant containing a conductive inducer | |
JP2008081673A (en) | Lubricant of magnetic fluid | |
JP4105862B2 (en) | Lubricating oil composition and bearing using the same | |
CN105802716B (en) | Grease for rolling bearing, rolling bearing device, and information recording/reproducing device | |
JP6055829B2 (en) | Lubricating oil composition | |
JP4777526B2 (en) | Oil-impregnated bearing and lubricating oil used for the bearing | |
JP2008280540A (en) | Oil for oil-impregnated bearing, oil-impregnated bearing using the oil, and pressurization motor | |
JP4170694B2 (en) | Oil-impregnated bearing oil, oil-impregnated bearing and pressurized motor using the same | |
US20060252659A1 (en) | Lubricating oil for dynamic fluid-pressure bearing, dynamic-fluid-pressure bearing, motor, and information recording/reproducing apparatus | |
JP5771799B2 (en) | Lubricant for bearing and use thereof | |
JP2007211234A (en) | Lubricating oil composition | |
JP4318502B2 (en) | Fluid bearing and spindle motor using the same | |
JP2008189786A (en) | Lubrication fluid for fluid bearing, fluid bearing and motor using it and lubrication method for fluid bearing | |
JP6744708B2 (en) | Rolling bearing grease, rolling bearing, rolling bearing device and information recording/reproducing device |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: IDEMITSU KOSAN CO., LTD., JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KAMIMURA, HIDETO;SHIMODA, SHUKICHI;HASHIMOTO, KATSUMI;REEL/FRAME:020040/0827 Effective date: 20071004 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |