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US20090029881A1 - Heat resistant lithium grease composition and a small motor reduced noise bearing - Google Patents

Heat resistant lithium grease composition and a small motor reduced noise bearing Download PDF

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Publication number
US20090029881A1
US20090029881A1 US11/659,045 US65904505A US2009029881A1 US 20090029881 A1 US20090029881 A1 US 20090029881A1 US 65904505 A US65904505 A US 65904505A US 2009029881 A1 US2009029881 A1 US 2009029881A1
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Prior art keywords
oil
grease composition
synthetic
weight
lithium
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US11/659,045
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Seiji Okamura
Motoharu Akiyama
Seiji Hashimoto
Hiroki Iwamatsu
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
    • C10M169/00—Lubricating compositions characterised by containing as components a mixture of at least two types of ingredient selected from base-materials, thickeners or additives, covered by the preceding groups, each of these compounds being essential
    • C10M169/02—Mixtures of base-materials and thickeners
    • 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
    • C10M169/06—Mixtures of thickeners 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
    • C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
    • C10M2203/10—Petroleum or coal fractions, e.g. tars, solvents, bitumen
    • C10M2203/102—Aliphatic fractions
    • C10M2203/1025—Aliphatic fractions used as base material
    • 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
    • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
    • C10M2205/02—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers
    • C10M2205/0206—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers used as base material
    • 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
    • C10M2205/00—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions
    • C10M2205/02—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers
    • C10M2205/026—Butene
    • C10M2205/0265—Butene used as base material
    • 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
    • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
    • C10M2207/04—Ethers; Acetals; Ortho-esters; Ortho-carbonates
    • C10M2207/0406—Ethers; Acetals; Ortho-esters; Ortho-carbonates used as base material
    • 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
    • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
    • C10M2207/10—Carboxylix acids; Neutral salts thereof
    • C10M2207/12—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms
    • C10M2207/125—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids
    • C10M2207/1256—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids used as thickening agent
    • 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
    • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
    • C10M2207/10—Carboxylix acids; Neutral salts thereof
    • C10M2207/12—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms
    • C10M2207/125—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids
    • C10M2207/128—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids containing hydroxy groups; Ethers thereof
    • C10M2207/1285—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of eight up to twenty-nine carbon atoms, i.e. fatty acids containing hydroxy groups; Ethers thereof used as thickening agents
    • 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
    • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
    • C10M2207/10—Carboxylix acids; Neutral salts thereof
    • C10M2207/12—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms
    • C10M2207/129—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of thirty or more carbon atoms
    • C10M2207/1296—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms having hydrocarbon chains of thirty or more carbon atoms used as thickening agents
    • 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
    • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
    • C10M2207/28—Esters
    • C10M2207/282—Esters of (cyclo)aliphatic oolycarboxylic acids
    • C10M2207/2825—Esters of (cyclo)aliphatic oolycarboxylic acids used as base material
    • 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
    • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
    • C10M2207/28—Esters
    • C10M2207/283—Esters of polyhydroxy compounds
    • C10M2207/2835—Esters of polyhydroxy compounds used as base material
    • 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
    • C10M2209/00—Organic macromolecular compounds containing oxygen as ingredients in lubricant compositions
    • C10M2209/02—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • C10M2209/08—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing monomers having an unsaturated radical bound to a carboxyl radical, e.g. acrylate type
    • C10M2209/086—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing monomers having an unsaturated radical bound to a carboxyl radical, e.g. acrylate type polycarboxylic, e.g. maleic acid
    • C10M2209/0863—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing monomers having an unsaturated radical bound to a carboxyl radical, e.g. acrylate type polycarboxylic, e.g. maleic acid used as base material
    • 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
    • C10M2215/06—Amines, e.g. polyalkylene polyamines; Quaternary amines having amino groups bound to carbon atoms of six-membered aromatic rings
    • C10M2215/064—Di- and triaryl amines
    • 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
    • C10M2215/10—Amides of carbonic or haloformic acids
    • C10M2215/102—Ureas; Semicarbazides; Allophanates
    • C10M2215/1026—Ureas; Semicarbazides; Allophanates used as thickening material
    • 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
    • C10M2219/04—Organic non-macromolecular compounds containing sulfur, selenium or tellurium as ingredients in lubricant compositions containing sulfur-to-oxygen bonds, i.e. sulfones, sulfoxides
    • C10M2219/044—Sulfonic acids, Derivatives thereof, e.g. neutral salts
    • 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
    • C10N2010/00—Metal present as such or in compounds
    • C10N2010/04—Groups 2 or 12
    • 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
    • C10N2020/04—Molecular weight; Molecular weight distribution
    • 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
    • C10N2030/08—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
    • C10N2030/76—Reduction of noise, shudder, or vibrations
    • 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
    • C10N2050/00—Form in which the lubricant is applied to the material being lubricated
    • C10N2050/10—Semi-solids; greasy

Definitions

  • the present invention relates to a heat resistant grease composition for motor bearings for small motors, particularly home electric appliances such as an air conditioner, motor bearings for imaging equipment such as blower fan and the like, and more specifically to a heat resistant, noise reduction grease sealed in a bearing for a small motor to reduce the rotation noise of the motor.
  • the prior art shows a grease composition in which 8 or more ester groups are arranged in a comb tooth form on one side of the chain molecules of oil composed of 8 or more carbon atoms.
  • the grease is formed by adding a urea thickener to a base oil in which a synthetic hydrocarbon oil and a synthetic ester oil are mixed in a weight ratio of 0.65-0.75:0.35-0.25. See Japanese Patent No. 3514574 and U.S. Pat. No. 5,910,470.
  • This grease is sealed in a ball bearing that supports a belt driven pulley placed in the vicinity of an automobile engine. Such devices makes a quick change in its rotation speed. To solve a problem of a unique whistle-like noise that is generated when used in cold climates, the grease is used.
  • a grease sealed in a similar bearing is shown in Japanese Laid Open Patent Application Publication No. 1994-306383.
  • a grease composition is sealed in a bearing.
  • the grease composition is formed by adding a urea thickener to a base oil in which a synthetic hydrocarbon oil and a synthetic ester oil are mixed in a weight ratio of 0.65-0.75:0.35-0.25.
  • Japanese Patent No. 3324628 shows that when noise reduction and vibration reduction are priority issues for a grease composition sealed in a bearing for an electronic calculator, semiconductor manufacturing device and the like, a noise and torque reducing grease is used.
  • the patent shows a grease with lithium soap as a thickener and an ester oil as a base oil. This lithium-soap-ester grease, however, tends to spatter and has a problem of damaging a recording medium if it is used as is. There is still a need in the art for improved noise reducing grease compositions sealed in a bearing for a small motor.
  • a heat resistant and noise-reduction grease composition that is desirably used in a bearing for a small motor is provided.
  • a sealed bearing containing the grease composition is provided which is desirably installed in small motor to reduce the rotation noise of the motor in use.
  • a heat resistant noise reduction lithium grease composition which has 5 to 20% preferably greater than 5% and less than 20% by weight of a lithium soap thickener.
  • the lithium soap thickener accounts for about 7.5% to about 17.5% by weight of the grease composition preferably about 10% to about 15% particularly about 12% to about 13% by weight.
  • the lithium soap thickener is composed of a long-chain fatty acid lithium soap with 26 to 32 carbon atoms.
  • the lithium soap thickener also includes a higher fatty acid lithium soap with 10 to 20 carbon atoms and/or a higher hydroxyfatty acid lithium soap with one or more hydroxyl groups and 10 or more carbon atoms.
  • the lithium grease composition also includes 95 to 80% by weight of a base oil.
  • the base oil contains a polymer ester oil in which 8 or more ester groups are arranged in a comb tooth form on one side of chain molecules which is expressed by Formula 1
  • the base oil has a viscosity (40° C.) of 30 to 100 mm 2 /s.
  • the polymer ester oil which is preferably present in the base oil in a significant amount preferably in an amount 20% by weight or higher preferably 20% to 50% by weight of the base oil.
  • the base oil includes, in addition to polymer ester oil of Formula 1 (A), one or more of synthetic ester oil (B), synthetic hydrocarbon oil (C), synthetic ether oil (D) and mineral oil (E).
  • polymer ester oil (A) accounts for 20 to 50% by weight of the total of the grease composition
  • synthetic hydrocarbon oil (C) accounts for 10 to 40% by weight of the total of the grease composition
  • mineral oil (E) accounts for 10 to 40% by weight of the total of the grease composition.
  • the polymer ester oil (A) accounts for 20 to 50% by weight of the total of the grease composition
  • the synthetic ester oil (B) accounts for 10 to 40% by weight of the total of the grease composition
  • the synthetic hydrocarbon oil (C) accounts for 10 to 40% by weight of the total of the grease composition.
  • the polymer ester oil (A) accounts for 20 to 50% by weight of the total of the grease composition
  • the synthetic ester oil (B) accounts for 10 to 30% by weight of the total of the grease composition
  • the synthetic hydrocarbon oil (C) accounts for 2 to 10% by weight of the total of the grease composition
  • synthetic ether oil (D) accounts for 10 to 30% by weight of the total of the grease composition.
  • the lithium soap thickener includes the long-chain fatty acid lithium soap with 26 to 32 carbon atoms in an amount of 0.1 to 10.0% by weight of the total of the grease composition, 12-hydroxystearic acid lithium soap lithium soap in an amount for 1.5 to 10.5% by weight of the total of the grease composition, and straight-chain fatty acid lithium soap with 10 to 20 carbon atoms in an amount of 0.5 to 5.0% by weight of the total of the grease composition.
  • an antioxidant, anticorrosive agent and the like may be added as additives to the heat-resistant lithium grease composition.
  • the heat-resistant lithium grease composition is desirably sealed in a small motor bearing to reduce noise.
  • the resulting composition has superior attachment to a metal surface.
  • a protective film forms quickly and evenly on the bearing metal surfaces.
  • the protective film can be maintained at a high temperature, which contributes to a longer operating life of the bearing.
  • the composition has an advantageous dispersibility and resolvability of the additives in the base oil which keeps the noise low during operation of a motor using the sealed bearing according to the invention.
  • FIG. 1 is a schematic view of an oil film measurement device used in the examples.
  • a heat resistant and noise reducing grease composition that is desirably used in a bearing for a small motor.
  • the grease filled bearing according to the invention is desirably used in a motor of imaging equipment such as a blower fan, a bearing of a motor of home electronic appliances such as an air conditioner.
  • a sealed bearing containing the composition is provided which is desirably installed in a small motor to reduce the rotation noise of the motor in use.
  • a heat resistant and noise reducing lithium grease composition which has 5 to 20% preferably greater than 5% and less than 20% by weight of a lithium soap thickener.
  • the lithium soap thickener accounts for about 7.5% to about 17.5% by weight of the grease composition preferably about 10% to about 15% particularly about 12% to about 13% by weight.
  • the lithium soap thickener is composed of a long-chain fatty acid lithium soap with 26 to 32 carbon atoms.
  • the lithium soap thickener also includes a higher fatty acid lithium soap with 10 to 20 carbon atoms and/or a higher hydroxyfatty acid lithium soap with one or more hydroxyl groups and 10 or more carbon atoms.
  • the lithium soap thickener includes the long-chain fatty acid lithium soap with 26 to 32 carbon atoms in an amount of 0.1 to 10.0% by weight of the total of the grease composition, 12-hydroxystearic acid lithium soap lithium soap in an amount for 1.5 to 10.5% by weight of the total of the grease composition, and straight-chain fatty acid lithium soap with 10 to 20 carbon atoms in an amount of 0.5 to 5.0% by weight of the total of the grease composition.
  • the lithium soap of long-chain fatty acid with 26 to 32 carbon atoms used in the present invention is obtained by bringing lithium hydroxide and a long-chain higher fatty acid with 26 to 32 carbon atoms to reaction to each other.
  • the long-chain fatty acid with 26 to 32 carbon atoms may be used singly or as a mixture. It is preferable to use a mixture of long-chain fatty acid with 26 to 32 carbon atoms containing montanic acid with 28 carbon atoms, preferably as a substantial component.
  • the lithium soap thickener utilized in the present invention includes together with the long-chain fatty acid with 26 to 32 carbon atoms, a lithium soap synthesized from lithium hydroxide and higher fatty acid with 10 to 20 carbon atoms and/or higher hydroxyfatty acid with one or more hydroxyl groups and 10 or more carbon atoms.
  • the grease becomes too thin, while if the lithium soap accounts for more than 20% by weight of the total of the grease composition, the grease becomes too thick.
  • the lithium grease composition also includes 95 to 80% by weight of a base oil.
  • the base oil includes a polymer ester oil in which 8 or more ester groups are arranged in a comb tooth form on one side of chain molecules which is expressed by Formula 1
  • the resulting base oil has a viscosity (40° C.) of 30 to 100 mm 2 /s.
  • the polymer ester oil is preferably present in the base oil in a significant amount preferably in an amount of preferably in an amount 20% by weight or higher preferably 20% to 50% by weight of the base oil.
  • the base oil desirably includes, one or more of synthetic ester oil (B), synthetic hydrocarbon oil (C), synthetic ether oil (D) and mineral oil (E). It is preferable that the polymer ester oil has a molecular weight of 1000 to 3000 and viscosity (40° C.) of 100 to 1000 mm 2 /s. and the resulting base oil has a viscosity (40° C.) of 30 to 100 mm 2 /s.
  • Polymer ester oil (A) utilized in the present invention can be any polymer ester that is expressed by the general formula
  • the polymer ester oil of Formula 1 have a molecular weight of 1000 to 3000 and viscosity (40° C.) of 100 to 1000 mm 2 /s.
  • the synthetic ester oil (B) used in the present invention is expressed by general formulae (a), (b) or (c) shown below.
  • R and R′ represent alkyl groups with 3 to 10 carbon atoms
  • other synthetic neopentyl polyol ester oils can be used.
  • Synthetic hydrocarbon oil (C) used in the present invention is preferably a poly- ⁇ -olefin oil, polybutene and olefin copolymer, with a viscosity (40° C.) of 20 to 100 mm 2 /s, and for the sake of safe use, it is preferable to adopt those with an ignition point of 220° C. or higher.
  • Polybutene is one kind of poly- ⁇ -olefin and can be produced by polymerizing a starting material mainly containing isobutylene by use of aluminum chloride as a catalyst. Polybutene may be used as it is or by adding hydrogen to it.
  • an alkyl diphenyl ether may be employed, namely dialkyl diphenyl ether, monoalkyl diphenyl ether, a mixture thereof and the like.
  • Mineral oil (E) utilized in the present invention is desirably a paraffinic oil with a viscosity (40° C.) of 90 to 150 mm 2 /s.
  • the polymer ester oil (A) accounts for 20 to 50% by weight of the total of the grease composition
  • synthetic hydrocarbon oil (C) accounts for 10 to 40% by weight of the total of the grease composition
  • mineral oil (E) accounts for 10 to 40% by weight of the total of the grease composition.
  • the polymer ester oil (A) accounts for 20 to 50% by weight of the total of the grease composition
  • the synthetic ester oil (B) accounts for 10 to 40% by weight of the total of the grease composition
  • the synthetic hydrocarbon oil (C) accounts for 10 to 40% by weight of the total of the grease composition.
  • the polymer ester oil (A) accounts for 20 to 50% by weight of the total of the grease composition
  • the synthetic ester oil (B) accounts for 10 to 30% by weight of the total of the grease composition
  • the synthetic hydrocarbon oil (C) accounts for 2 to 10% by weight of the total of the grease composition
  • synthetic ether oil (D) accounts for 10 to 30% by weight of the total of the grease composition.
  • the grease composition of the present invention may contain various additives that are commonly used for greases.
  • additives include additives commonly used for a grease composition, namely antioxidants such as phenyl- ⁇ ( ⁇ )-naphtylamine, alkyl diphenylamine, phenothiazine, t-butylphenol and the like, and anticorrosive agents such as metal sulfonate, non-ionic anticorrosive agents, amine anticorrosive agents an the like.
  • lithium soap synthesized from lithium hydroxide a long-chain fatty acid mixture with 26 to 32 carbon atoms containing 28-carbon-atom montanic acid as a substantial component, stearic acid and 12-hydroxystearic acid was employed.
  • polymer ester oils with a viscosity (40° C.) of approximately 800 mm 2 /s (Examples 1-6) and of approximately 140 mm 2 /s (Examples 7-10) were used.
  • a synthetic ester oil a tetraester oil (pentaerythritol ester) was used.
  • poly- ⁇ -olefin oil As a synthetic hydrocarbon oil, poly- ⁇ -olefin oil was adopted.
  • alkyl diphenylamine was employed as an antioxidant, and calcium sulphonate was employed as an anticorrosive agent.
  • the components were mixed in ratios as shown in Table 1, and heated to 220 to 230° C. while agitating until the entire mixture became fluid. Each was poured into a stainless container so as to have a thickness of 3 to 5 mm and cooled to 50° C. or lower, and a grease composition was obtained by homogenizing with a three-roll mill. The component ratios of the grease compositions and the results of the tests are indicated in Table 1.
  • comparative grease compositions 1-4 were prepared by mixing various components. Two commercially available greases with known base oils and thickeners were used as comparative examples 5 and 6, as shown in Table 2. In Table 2, the symbol ++ denotes a component that is mixed in.
  • the base oil viscosity (40° C.) was obtained on the basis of JIS K2283, while the mixture thickness was obtained on the basis of JIS K2220 7.
  • the dropping point was obtained on the basis of JIS K2220 8.
  • grease components to be tested were sealed in a small bearing, whereupon their acoustic properties were measured at room temperature, and also their volatile amounts and the acoustic properties (acoustic life duration) of the bearings were measured after 1000 hours of the bearing rotation test at rotation frequency of 3000 min ⁇ 1 under an atmosphere temperature of 100° C.
  • the Anderon values were measured using an Anderon meter before and after the bearing rotation test.
  • the bearing was weighed before and after the bearing rotation test, and the difference was obtained.
  • the results of judgment made in accordance with performances required for a motor bearing grease composition were listed in Table 1 (examples) and Table 2 (comparative examples). A smaller Anderon values indicates greater acoustic properties, and a smaller volatile amount is superior in performance.
  • the heat resistance test was carried out by the oil film measurement method utilizing optical interference method. A thicker oil film with a higher temperature is superior. An oil film measurement device is shown in FIG. 1 .

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Abstract

A heat-resistant noise-reduction grease and a bearing containing the grease for a small motor such as a motor for imaging equipment such as a blower fan and motor bearing for a household electrical appliance such as an air conditioner, which is eco-friendly and excellent in noise-reduction properties is provided.
The heat-resistant lithium grease composition is composed of 5 to 20% by weight of a thickener and 95 to 80% by weight of a base oil, wherein long-chain fatty acid lithium soap with 26 to 32 carbon atoms and lithium soap comprising a higher fatty acid with 10 to 20 carbon atoms and/or a higher hydroxyfatty acid with one or more hydroxyl groups and 10 or more carbon atoms are used as the thickener, and the base oil contains, as a main component, polymer ester oil (A) in which 8 or more ester groups are arranged in comb tooth form on one side of chain molecules of oil constituted with 8 or more carbon atoms, which is expressed by the following general formula:
Figure US20090029881A1-20090129-C00001
(where each of R1, R2, R3 and R4 represents an alkyl group, x represents an integer satisfying x≧2, and y represents an integer satisfying y≧2).
and the base oil has a viscosity (40° C.) of 30 to 100 mm2/s.

Description

    TECHNICAL FIELD
  • The present invention relates to a heat resistant grease composition for motor bearings for small motors, particularly home electric appliances such as an air conditioner, motor bearings for imaging equipment such as blower fan and the like, and more specifically to a heat resistant, noise reduction grease sealed in a bearing for a small motor to reduce the rotation noise of the motor.
    • BACKGROUND ART
  • Generally the use of greases sealed in a bearing is known. The prior art shows a grease composition in which 8 or more ester groups are arranged in a comb tooth form on one side of the chain molecules of oil composed of 8 or more carbon atoms. The grease is formed by adding a urea thickener to a base oil in which a synthetic hydrocarbon oil and a synthetic ester oil are mixed in a weight ratio of 0.65-0.75:0.35-0.25. See Japanese Patent No. 3514574 and U.S. Pat. No. 5,910,470. This grease is sealed in a ball bearing that supports a belt driven pulley placed in the vicinity of an automobile engine. Such devices makes a quick change in its rotation speed. To solve a problem of a unique whistle-like noise that is generated when used in cold climates, the grease is used.
  • A grease sealed in a similar bearing is shown in Japanese Laid Open Patent Application Publication No. 1994-306383. There a grease composition is sealed in a bearing. The grease composition is formed by adding a urea thickener to a base oil in which a synthetic hydrocarbon oil and a synthetic ester oil are mixed in a weight ratio of 0.65-0.75:0.35-0.25.
  • Japanese Patent No. 3324628 shows that when noise reduction and vibration reduction are priority issues for a grease composition sealed in a bearing for an electronic calculator, semiconductor manufacturing device and the like, a noise and torque reducing grease is used. The patent shows a grease with lithium soap as a thickener and an ester oil as a base oil. This lithium-soap-ester grease, however, tends to spatter and has a problem of damaging a recording medium if it is used as is. There is still a need in the art for improved noise reducing grease compositions sealed in a bearing for a small motor.
    • DISCLOSURE OF THE INVENTION
  • According to the invention, a heat resistant and noise-reduction grease composition that is desirably used in a bearing for a small motor is provided. In another aspect of the invention, a sealed bearing containing the grease composition is provided which is desirably installed in small motor to reduce the rotation noise of the motor in use.
  • According to the invention a heat resistant noise reduction lithium grease composition is provided which has 5 to 20% preferably greater than 5% and less than 20% by weight of a lithium soap thickener. Desirably, the lithium soap thickener accounts for about 7.5% to about 17.5% by weight of the grease composition preferably about 10% to about 15% particularly about 12% to about 13% by weight. The lithium soap thickener is composed of a long-chain fatty acid lithium soap with 26 to 32 carbon atoms. The lithium soap thickener also includes a higher fatty acid lithium soap with 10 to 20 carbon atoms and/or a higher hydroxyfatty acid lithium soap with one or more hydroxyl groups and 10 or more carbon atoms.
  • The lithium grease composition also includes 95 to 80% by weight of a base oil. The base oil contains a polymer ester oil in which 8 or more ester groups are arranged in a comb tooth form on one side of chain molecules which is expressed by Formula 1
  • Figure US20090029881A1-20090129-C00002
  • (where each of R1, R2, R3 and R4 represents an alkyl group, x is an integer satisfying x≧2, and y is an integer satisfying y≧2). The base oil has a viscosity (40° C.) of 30 to 100 mm2/s.
    The polymer ester oil which is preferably present in the base oil in a significant amount preferably in an amount 20% by weight or higher preferably 20% to 50% by weight of the base oil.
  • Desirably, the base oil includes, in addition to polymer ester oil of Formula 1 (A), one or more of synthetic ester oil (B), synthetic hydrocarbon oil (C), synthetic ether oil (D) and mineral oil (E). Desirably the polymer ester oil (A) accounts for 20 to 50% by weight of the total of the grease composition, synthetic hydrocarbon oil (C) accounts for 10 to 40% by weight of the total of the grease composition, and mineral oil (E) accounts for 10 to 40% by weight of the total of the grease composition. Optionally according to the invention, the polymer ester oil (A) accounts for 20 to 50% by weight of the total of the grease composition, the synthetic ester oil (B) accounts for 10 to 40% by weight of the total of the grease composition, and the synthetic hydrocarbon oil (C) accounts for 10 to 40% by weight of the total of the grease composition. Advantageously, according to the present invention, the polymer ester oil (A) accounts for 20 to 50% by weight of the total of the grease composition, the synthetic ester oil (B) accounts for 10 to 30% by weight of the total of the grease composition, the synthetic hydrocarbon oil (C) accounts for 2 to 10% by weight of the total of the grease composition, and synthetic ether oil (D) accounts for 10 to 30% by weight of the total of the grease composition.
  • Preferably the lithium soap thickener includes the long-chain fatty acid lithium soap with 26 to 32 carbon atoms in an amount of 0.1 to 10.0% by weight of the total of the grease composition, 12-hydroxystearic acid lithium soap lithium soap in an amount for 1.5 to 10.5% by weight of the total of the grease composition, and straight-chain fatty acid lithium soap with 10 to 20 carbon atoms in an amount of 0.5 to 5.0% by weight of the total of the grease composition.
  • Desirably an antioxidant, anticorrosive agent and the like may be added as additives to the heat-resistant lithium grease composition.
  • The heat-resistant lithium grease composition is desirably sealed in a small motor bearing to reduce noise. The resulting composition has superior attachment to a metal surface. As a result in use, a protective film forms quickly and evenly on the bearing metal surfaces. The protective film can be maintained at a high temperature, which contributes to a longer operating life of the bearing. Furthermore, the composition has an advantageous dispersibility and resolvability of the additives in the base oil which keeps the noise low during operation of a motor using the sealed bearing according to the invention.
  • The preferred embodiment of the present invention is illustrated in the examples. However, it should be expressly understood that the present invention should not be limited solely to the illustrative embodiment.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a schematic view of an oil film measurement device used in the examples.
    •  MODES FOR CARRYING OUT THE INVENTION
  • According to the invention, a heat resistant and noise reducing grease composition that is desirably used in a bearing for a small motor is provided. The grease filled bearing according to the invention is desirably used in a motor of imaging equipment such as a blower fan, a bearing of a motor of home electronic appliances such as an air conditioner. In another aspect of the invention, a sealed bearing containing the composition is provided which is desirably installed in a small motor to reduce the rotation noise of the motor in use.
  • According to the invention a heat resistant and noise reducing lithium grease composition is provided which has 5 to 20% preferably greater than 5% and less than 20% by weight of a lithium soap thickener. Desirably, the lithium soap thickener accounts for about 7.5% to about 17.5% by weight of the grease composition preferably about 10% to about 15% particularly about 12% to about 13% by weight. The lithium soap thickener is composed of a long-chain fatty acid lithium soap with 26 to 32 carbon atoms. The lithium soap thickener also includes a higher fatty acid lithium soap with 10 to 20 carbon atoms and/or a higher hydroxyfatty acid lithium soap with one or more hydroxyl groups and 10 or more carbon atoms. Preferably the lithium soap thickener includes the long-chain fatty acid lithium soap with 26 to 32 carbon atoms in an amount of 0.1 to 10.0% by weight of the total of the grease composition, 12-hydroxystearic acid lithium soap lithium soap in an amount for 1.5 to 10.5% by weight of the total of the grease composition, and straight-chain fatty acid lithium soap with 10 to 20 carbon atoms in an amount of 0.5 to 5.0% by weight of the total of the grease composition. Advantageously, the lithium soap of long-chain fatty acid with 26 to 32 carbon atoms used in the present invention is obtained by bringing lithium hydroxide and a long-chain higher fatty acid with 26 to 32 carbon atoms to reaction to each other. The long-chain fatty acid with 26 to 32 carbon atoms may be used singly or as a mixture. It is preferable to use a mixture of long-chain fatty acid with 26 to 32 carbon atoms containing montanic acid with 28 carbon atoms, preferably as a substantial component.
  • Desirably the lithium soap thickener utilized in the present invention includes together with the long-chain fatty acid with 26 to 32 carbon atoms, a lithium soap synthesized from lithium hydroxide and higher fatty acid with 10 to 20 carbon atoms and/or higher hydroxyfatty acid with one or more hydroxyl groups and 10 or more carbon atoms.
  • In the present invention, if the lithium soap accounts for less than 5% by weight of the total of the grease composition, the grease becomes too thin, while if the lithium soap accounts for more than 20% by weight of the total of the grease composition, the grease becomes too thick.
  • The lithium grease composition also includes 95 to 80% by weight of a base oil. The base oil includes a polymer ester oil in which 8 or more ester groups are arranged in a comb tooth form on one side of chain molecules which is expressed by Formula 1
  • Figure US20090029881A1-20090129-C00003
  • (where each of R1, R2, R3 and R4 represents an alkyl group, x is an integer satisfying x≧2, and y is an integer satisfying y≧2).
    The resulting base oil has a viscosity (40° C.) of 30 to 100 mm2/s. The polymer ester oil is preferably present in the base oil in a significant amount preferably in an amount of preferably in an amount 20% by weight or higher preferably 20% to 50% by weight of the base oil.
  • In addition to polymer ester oil (A), the base oil desirably includes, one or more of synthetic ester oil (B), synthetic hydrocarbon oil (C), synthetic ether oil (D) and mineral oil (E). It is preferable that the polymer ester oil has a molecular weight of 1000 to 3000 and viscosity (40° C.) of 100 to 1000 mm2/s. and the resulting base oil has a viscosity (40° C.) of 30 to 100 mm2/s.
  • Polymer ester oil (A) utilized in the present invention can be any polymer ester that is expressed by the general formula
  • Figure US20090029881A1-20090129-C00004
  • (where each of R1, R2, R3 and R4 represents an alkyl group, x represents an integer satisfying x≧2, and y represents an integer satisfying y≧2). It is preferable, that the polymer ester oil of Formula 1 have a molecular weight of 1000 to 3000 and viscosity (40° C.) of 100 to 1000 mm2/s.
  • The synthetic ester oil (B) used in the present invention is expressed by general formulae (a), (b) or (c) shown below.
  • A synthetic diester oil expressed by general formula (a):

  • RCOOH(CH2)nCOOR′  (a)
  • (where R and R′ represent alkyl groups with 3 to 18 carbon atoms, and can be identical or different from each other, and n is 3 to 12);
    a synthetic trimester oil expressed by general formula (b):

  • R(CH2COO R′)3  (b)
  • (where R and R′ represent alkyl groups with 3 to 10 carbon atoms);
    a synthetic tetraester oil expressed by general formula (c):

  • R(CH2COOR′)4  (c)
  • (where R and R′ represent alkyl groups with 3 to 10 carbon atoms); and other synthetic neopentyl polyol ester oils can be used.
  • Synthetic hydrocarbon oil (C) used in the present invention is preferably a poly-α-olefin oil, polybutene and olefin copolymer, with a viscosity (40° C.) of 20 to 100 mm2/s, and for the sake of safe use, it is preferable to adopt those with an ignition point of 220° C. or higher.
  • These have a structure in which α-olefin is low-polymerized to obtain an oligomer and hydrogen is added to its terminal double bond, a typical formula of which may be as follows:
  • Figure US20090029881A1-20090129-C00005
  • (where R represents an alkyl group, and n represents an integer of 1 to 6). Polybutene is one kind of poly-α-olefin and can be produced by polymerizing a starting material mainly containing isobutylene by use of aluminum chloride as a catalyst. Polybutene may be used as it is or by adding hydrogen to it.
  • As synthetic ether oil (D) utilized in the present invention, an alkyl diphenyl ether may be employed, namely dialkyl diphenyl ether, monoalkyl diphenyl ether, a mixture thereof and the like.
  • Mineral oil (E) utilized in the present invention is desirably a paraffinic oil with a viscosity (40° C.) of 90 to 150 mm2/s.
  • Desirably the polymer ester oil (A) accounts for 20 to 50% by weight of the total of the grease composition, synthetic hydrocarbon oil (C) accounts for 10 to 40% by weight of the total of the grease composition, and mineral oil (E) accounts for 10 to 40% by weight of the total of the grease composition. Optionally according to the invention, the polymer ester oil (A) accounts for 20 to 50% by weight of the total of the grease composition, the synthetic ester oil (B) accounts for 10 to 40% by weight of the total of the grease composition, and the synthetic hydrocarbon oil (C) accounts for 10 to 40% by weight of the total of the grease composition. ester oil (B), synthetic hydrocarbon oil (C), synthetic ether oil (D) and mineral oil (E). Advantageously, according to the present invention, the polymer ester oil (A) accounts for 20 to 50% by weight of the total of the grease composition, the synthetic ester oil (B) accounts for 10 to 30% by weight of the total of the grease composition, the synthetic hydrocarbon oil (C) accounts for 2 to 10% by weight of the total of the grease composition, and synthetic ether oil (D) accounts for 10 to 30% by weight of the total of the grease composition.
  • The grease composition of the present invention may contain various additives that are commonly used for greases. Such additives include additives commonly used for a grease composition, namely antioxidants such as phenyl-α(β)-naphtylamine, alkyl diphenylamine, phenothiazine, t-butylphenol and the like, and anticorrosive agents such as metal sulfonate, non-ionic anticorrosive agents, amine anticorrosive agents an the like.
  • Specific embodiments will be discussed next; however, the present invention should not be restricted by them.
    • EXAMPLES 1 TO 10
  • As a thickener, lithium soap synthesized from lithium hydroxide, a long-chain fatty acid mixture with 26 to 32 carbon atoms containing 28-carbon-atom montanic acid as a substantial component, stearic acid and 12-hydroxystearic acid was employed.
  • As a base oil, polymer ester oils with a viscosity (40° C.) of approximately 800 mm2/s (Examples 1-6) and of approximately 140 mm2/s (Examples 7-10) were used. As a synthetic ester oil, a tetraester oil (pentaerythritol ester) was used.
  • As a synthetic hydrocarbon oil, poly-α-olefin oil was adopted.
  • As a synthetic ether oil, an alkyl diphenyl ether oil was adopted.
  • Moreover, alkyl diphenylamine was employed as an antioxidant, and calcium sulphonate was employed as an anticorrosive agent.
  • The components were mixed in ratios as shown in Table 1, and heated to 220 to 230° C. while agitating until the entire mixture became fluid. Each was poured into a stainless container so as to have a thickness of 3 to 5 mm and cooled to 50° C. or lower, and a grease composition was obtained by homogenizing with a three-roll mill. The component ratios of the grease compositions and the results of the tests are indicated in Table 1.
  • TABLE 1
    Example
    (1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
    Composition Thickener Higher 8.0 6.0 4.0 1.5 8.0 4.0 9.0 10.5 10.5 10.5
    hydroxy-
    fatty acid
    lithium soap
    Higher fatty 1.5 1.0 0.5 .05 1.5 1.0 1.5 1.5 2.0 1.5
    acid lithium
    soap
    Long-chain 2.5 5.0 7.5 10.0 2.5 5.0 2.5 1.0 0.5 1.0
    fatty acid
    lithium soap
    Base oil Polymer 20.0 20.0 20.0 20.0 20.0 20.0 40.0 40.0 40.0 20.0
    ester oil
    Synthetic 32.5 32.5 32.5 32.5 33.5 30.0 30.0 30.0 4.0
    hydrocarbon
    oil
    Mineral oil 32.5 32.5 32.5 32.5 32.5 33.5
    Pentaerythritol 32.5 14.0 14.0 14.0 30.0
    ester oil
    Alkyl 30.0
    diphenyl
    ether oil
    Additive Antioxidant 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0
    Anticorrosive
    agent,
    etc.
    Property Base oil (40° C.) 97.76 97.76 97.76 97.76 80.26 96.21 55.46 55.46 55.46 53.85
    and viscosity mm2/s
    performance Mixture (25° C.) 273 268 275 264 265 287 261 258 255 259
    thickness
    Dropping ° C. 192 189 191 187 194 190 185 188 188 187
    point
    Heat resistance A A A A A A A A A A
    Bearing Acoustic A A A A A A A A A A
    characteristics properties
    Volatilization A A A A A A B B B A
    reduction
    Long A A A A A A A A A A
    lifespan
    Overall evaluation A A A A A A B B B A
    • COMPARATIVE EXAMPLES 1 TO 6
  • In the same manner as in the Examples 1 to 10, comparative grease compositions 1-4 were prepared by mixing various components. Two commercially available greases with known base oils and thickeners were used as comparative examples 5 and 6, as shown in Table 2. In Table 2, the symbol ++ denotes a component that is mixed in.
  • The results of the tests are shown in Table 2.
  • TABLE 2
    Comparative
    Example
    (1) (2) (3) (4) (5) (6)
    Composition Thickener Higher 8.5 8.5 5.0 10.5
    hydroxyfatty acid
    lithium soap
    Higher fatty acid 3.5 3.5 7.0 1.5
    lithium soap
    Long-chain fatty
    acid lithium soap
    Urea compound ++ ++
    Base oil Polymer ester oil
    Synthetic 85.0 85.0 85.0 ++
    hydrocarbon oil
    Mineral oil 85.0 ++ ++
    Pentaerythritol
    ester oil
    Alkyl diphenyl
    ether oil
    Additive Antioxidant 3.0 3.0 3.0 3.0 ++ ++
    Anticorrosive
    agent, etc.
    Property and Base oil viscosity (40° C.) 99.85 30.47 30.47 30.47 41.25 108.4
    performance mm2/s
    Mixture thickness (25° C.) 257 268 298 248 242 280
    Dropping point ° C. 186 188 191 194 250 250
    or or
    higher higher
    Heat resistance C D D C B A
    Bearing Acoustic properties A A A A C C
    characteristics
    Volatilization B C C C C B
    reduction
    Long lifespan D C C B A B
    Overall evaluation D D D C C C
    • DISCUSSIONS OF EXAMPLES
  • The base oil viscosity (40° C.) was obtained on the basis of JIS K2283, while the mixture thickness was obtained on the basis of JIS K2220 7. The dropping point was obtained on the basis of JIS K2220 8. In the bearing characteristics test, grease components to be tested were sealed in a small bearing, whereupon their acoustic properties were measured at room temperature, and also their volatile amounts and the acoustic properties (acoustic life duration) of the bearings were measured after 1000 hours of the bearing rotation test at rotation frequency of 3000 min−1 under an atmosphere temperature of 100° C. Regarding the acoustic properties, the Anderon values were measured using an Anderon meter before and after the bearing rotation test. As for the volatile amount, the bearing was weighed before and after the bearing rotation test, and the difference was obtained. In relation to the evaluation results of each, the results of judgment made in accordance with performances required for a motor bearing grease composition were listed in Table 1 (examples) and Table 2 (comparative examples). A smaller Anderon values indicates greater acoustic properties, and a smaller volatile amount is superior in performance.
  • The heat resistance test was carried out by the oil film measurement method utilizing optical interference method. A thicker oil film with a higher temperature is superior. An oil film measurement device is shown in FIG. 1.
  • After applying a test grease on a disk, the measurement is carried out in a point contact state, by rotating the disk under a load from under a ball in a direction toward the bottom surface of the disk. (See Tribology Conference Abstracts for the Japanese Society of Tribologists, Tokyo 1997-5, p. 328.)
  • The following is the measurement conditions:
  • Load 20N (maximum hertz pressure 0.53 GPa, osculating circle diameter 0.27 mm)
    Rotational speed 1.7 m/s (corresponding to 3000 min−1 with a Model 608 bearing) Temperature 120° C.
    Ball bearing steel ball (¾ inch in diameter)
    Disk chromium/silica deposition glass disk, 10 cm in diameter
  • The evaluation was made on 4-level scale. “A” is particularly favorable, “B” is favorable, “C” is average, and “D” is poor.
  • The foregoing is considered as illustrative only to the principles of the invention. Further, since numerous changes and modification will occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described above, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

Claims (74)

1. A heat resistant lithium grease composition comprising:
a) more than 5% to less than 20% by weight of a lithium soap thickener;
b) said lithium soap thickener comprising a long-chain fatty acid lithium soap with 26 to 32 carbon atoms and
i) a higher fatty acid lithium soap with 10 to 20 carbon atoms or
ii) a higher hydroxyfatty acid lithium soap with one or more hydroxyl groups and 10 or more carbon atoms, or
iii) both i and ii;
c) 95 to 80% by weight of a base oil;
d) said base oil including a polymer ester oil in which 8 or more ester groups are arranged in a comb tooth form on one side of chain molecules which is expressed by Formula 1
Figure US20090029881A1-20090129-C00006
(where each of R1, R2, R3 and R4 represents an alkyl group, x is an integer satisfying x≧2, and y is an integer satisfying y≧2)
and said base oil having a viscosity (40° C.) of 30 to 100 mm2/s.
2. The lithium grease composition according to claim 1 wherein the lithium soap thickener is about 7.5% to about 17.5% by wt.
3. The lithium grease composition according to claim 1 wherein the lithium soap thickener is about 10% to about 15% by wt.
4. The lithium grease composition according to claim 2 wherein the lithium soap thickener includes a montanic acid lithium soap.
5. The lithium grease composition according to claim 4 wherein the lithium soap thickener includes a montanic acid lithium soap as a substantial component.
6. The lithium grease composition according to claim 1 wherein said long-chain fatty acid lithium soap with 26 to 32 carbon atoms is present in an amount of 0.1 to 10.0% by weight of the total of the grease composition.
7. The lithium grease composition according to claim 1 wherein said thickener includes 12-hydroxystearic acid lithium soap lithium soap in an amount of 1.5 to 10.5% by weight of the total of the grease composition
8. The lithium grease composition according to claim 1 wherein said straight-chain fatty acid lithium soap with 10 to 20 carbon atoms in an amount of 0.5 to 5.0% by weight of the total of the grease composition.
9. The lithium grease composition according to claim 1 further comprising said base oil includes a synthetic ester oil, a synthetic hydrocarbon oil, a synthetic ether oil or mineral oil.
10. The lithium grease composition according to claim 1 further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, a synthetic ether oil and mineral oil.
11. The lithium grease composition according to claim 1 further comprising said base oil comprising a synthetic hydrocarbon oil.
12. The lithium grease composition according to claim 1 further comprising said base oil including a synthetic hydrocarbon oil, and a mineral oil.
13. The lithium grease composition according to claim 1 further comprising said base oil including a synthetic hydrocarbon oil and a synthetic ester oil.
14. The lithium grease composition according to claim 1 further comprising said base oil including a synthetic hydrocarbon oil and a synthetic ether oil.
15. The lithium grease composition according to claim 1 further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, and a mineral oil.
16. The lithium grease composition according to claim 1 further comprising said base oil including a synthetic ether oil, a synthetic hydrocarbon oil, and a mineral oil.
17. The lithium grease composition according to claim 1 further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, and a synthetic ether oil.
18. The lithium grease composition according to claim 1 further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, a synthetic ether oil and mineral oil.
19. The lithium grease composition according to claim 1 further comprising said base oil including a mineral oil.
20. The lithium grease composition according to claim 1 further comprising said base oil including a synthetic ester oil and a mineral oil.
21. The lithium grease composition according to claim 1 further comprising said base oil including a synthetic ether oil and a mineral oil.
22. The lithium grease composition according to claim 1 further comprising said base oil including a synthetic ester oil, a synthetic ether oil and mineral oil.
23. The lithium grease composition according to claim 1 wherein said polymer ester oil in an amount of 20% to 50% by weight of the total of the grease composition, said base oil including a synthetic hydrocarbon oil in an amount of 10% to 40% by weight of the total of the grease composition, and a mineral oil in an amount of 10 to 40% by weight of the total grease composition.
24. The lithium grease composition according to claim 1 further comprising said polymer ester oil in an amount of 20% to 50% by weight of the total of the grease composition, said base oil including a synthetic ester oil in an amount of 10% to 40% by weight of the total of the grease composition, and a synthetic hydrocarbon oil in an amount of 10 to 40% by weight of the total of the grease composition.
25. The lithium grease composition according to claim 1 further comprising said polymer ester oil in an amount of 20% to 50% by weight of the total of the grease composition, said base oil including a synthetic ester oil in an amount of 10% to 30% by weight of the total of the grease composition, a synthetic hydrocarbon oil in an amount of 2 to 10% by weight of the total of the grease composition, and a synthetic ether in an amount of 10% to 30% by weight of the total of the grease composition.
26. The lithium grease composition according to claim 1 further comprising said grease composition includes an antioxidant or an anticorrosive agent or both an antioxidant and an anticorrosive agent.
27. The lithium grease composition according to any one of claim 9 further comprising said grease composition includes an antioxidant or an anticorrosive agent or both an antioxidant and an anticorrosive agent.
28. The lithium grease composition sealed according to claim 1 wherein said polymer ester oil is present in an amount of 20% to 50% by weight of said grease composition.
29. The lithium grease composition according to claim 1 wherein said polymer ester oil is present in a significant amount of 20% or greater by weight of said base oil.
30. The lithium grease composition according to claim 1 wherein said polymer ester oil has a molecular weight of 1000 to 3000 and a viscosity (40° C.) of 100 to 1000 mm2/s.
31. The lithium grease composition according to claim 9 wherein in d said polymer ester oil has a molecular weight of 1000 to 3000 and a viscosity (40° C.) of 100 to 1000 mm2/s.
32. The lithium grease composition according to claim 9 wherein said synthetic ester oil is
a) a synthetic diester oil having the formula:

RCOOH(CH2)nCOOR′
(where R and R′ represent alkyl groups with 3 to 18 carbon atoms, and can be identical or different from each other, and n is 3 to 12.);
b) a synthetic trimester oil having the formula

R(CH2COOR′)3
(where R and R′ represent alkyl groups with 3 to 10 carbon atoms);
c) a synthetic tetraester oil having the formula

R(CH2COOR′)4
(where R and R′ represent alkyl groups with 3 to 10 carbon atoms); or
d) a synthetic neopentyl polyol ester oil.
33. The lithium grease composition according to claim 9 wherein said synthetic hydrocarbon oil is a poly-α-olefin oil or a polybutene and olefin copolymer, that has a viscosity (40° C.) of 20 to 100 mm2/s.
34. The lithium grease composition according to claim 9 wherein said synthetic ether oil is an alkyl diphenyl ether.
35. The lithium grease composition according to claim 3 claim 1 wherein said synthetic ether oil is dialkyl diphenyl ether, monoalkyl diphenyl ether, or a mixture thereof.
36. The lithium grease composition according to claim 9 wherein said mineral oil is a paraffinic oil with a viscosity (40° C.) of 90 to 150 mm2/s.
37. A low noise small motor bearing comprising:
a bearing;
a heat resistant lithium grease composition sealed in said bearing;
said heat resistant lithium grease composition comprising:
a) more than 5% to less than 20% by weight of a lithium soap thickener;
b) said lithium soap thickener comprising a long-chain fatty acid lithium soap with 26 to 32 carbon atoms and
i) a higher fatty acid lithium soap with 10 to 20 carbon atoms, or
ii) a higher hydroxyfatty acid lithium soap with one or more hydroxyl groups and 10 or more carbon atoms, or
iii) both i and ii;
c) 95 to 80% by weight of a base oil;
d) said base oil including a polymer ester oil in which 8 or more ester groups are arranged in a comb tooth form on one side of chain molecules which is expressed by Formula 1
Figure US20090029881A1-20090129-C00007
(where each of R1, R2, R3 and R4 represents an alkyl group, x is an integer satisfying x≧2, and y is an integer satisfying y≧2)
and said base oil having a viscosity (40° C.) of 30 to 100 mm2/s.
38. A low noise small motor bearing according to claim 37 wherein the lithium soap thickener is about 7.5% to about 17.5% by wt.
39. A low noise small motor bearing according to claim 37 wherein the lithium soap thickener is about 10% to about 15% by wt.
40. A low noise small motor bearing according to claim 38 where in the lithium soap thickener includes a montanic acid lithium soap.
41. A low noise small motor bearing according to claim 40 where in the lithium soap thickener includes a montanic acid lithium soap in an substantial amount.
42. A low noise small motor bearing according to claim 37 wherein said long-chain fatty acid lithium soap with 26 to 32 carbon atoms is present in an amount of 0.1 to 10.0% by weight of the total of the grease composition.
43. A low noise small motor bearing according to claim 37 wherein said thickener includes 12-hydroxystearic acid lithium soap in an amount of 105 to 10.5% by weight of the total of the grease composition.
44. A low noise small motor bearing according to claim 37 wherein said straight-chain fatty acid lithium soap with 10 to 20 carbon atoms is present in an amount of 0.5 to 5.0 by weight of the total of the total grease composition.
45. A low noise small motor bearing according to claim 37 further comprising said base oil including synthetic ester oil, a synthetic hydrocarbon oil, a synthetic ether oil or mineral oil.
46. A low noise small motor bearing according to claim 37 further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, a synthetic ether oil and mineral oil.
47. A low noise small motor bearing according to claim 37 further comprising said base oil comprising a synthetic hydrocarbon oil.
48. A low noise small motor bearing according to claim 37 further comprising said base oil including a synthetic hydrocarbon oil and a mineral oil.
49. A low noise small motor bearing according to claim 37 further comprising said base oil including a synthetic hydrocarbon oil and a synthetic ester oil.
50. A low noise small motor bearing according to claim 37 further comprising said base oil including a synthetic hydrocarbon oil and a synthetic ether oil.
51. A low noise small motor bearing according to claim 37 further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, and a mineral oil.
52. A low noise small motor bearing according to claim 37 further comprising said base oil including a synthetic ether oil, a synthetic hydrocarbon oil, and a mineral oil.
53. A low noise small motor bearing according to claim 37 further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, and a synthetic ether oil.
54. A low noise small motor bearing according to claim 37 further comprising said base oil including a synthetic ester oil, a synthetic hydrocarbon oil, synthetic ether oil and mineral oil.
55. A low noise small motor bearing according to claim 37 further comprising said base oil including a mineral oil.
56. A low noise small motor bearing according to claim 37 further comprising said base oil including a synthetic ester oil and mineral oil.
57. A low noise small motor bearing according to claim 37 further comprising said base oil including a synthetic ether oil and mineral oil.
58. A low noise small motor bearing according to claim 37 further comprising said base oil including a synthetic ester oil, a synthetic ether oil and mineral oil.
59. A low noise small motor bearing according to claim 37 wherein said polymer ester oil in an amount of 20 to 50% by weight of the total of the grease composition, said base oil including a synthetic hydrocarbon oil in an amount of 10 to 40% by weight of the total of the grease composition, and a mineral oil in an amount of 10 to 40% by weight of the total grease composition.
60. A low noise small motor bearing according to claim further comprising said polymer ester oil in an amount of 20 to 50% by weight of the total of the grease composition, said base oil including a synthetic ester oil in an amount of 10 to 40% by weight of the total of the grease composition, and a synthetic hydrocarbon oil in an amount of 10 to 40% by weight of the total of the grease composition.
61. A low noise small motor bearing according to claim 37 further comprising said polymer ester oil in an amount of 20 to 50% by weight of the total of the grease composition, said base oil including a synthetic ester oil in an amount of 10 to 30% by weight of the total of the grease composition, a synthetic hydrocarbon oil in an amount of 2 to 10% by weight of the total of the grease composition, and a synthetic ether in an amount of 10 to 30% by weight of the total of the grease composition.
62. A low noise small motor bearing according to claim 37 further comprising said grease composition includes an antioxidant or an anticorrosive agent or both an antioxidant and an anticorrosive agent.
63. A low noise small motor bearing according to claim 45 further comprising said grease composition includes an antioxidant or an anticorrosive agent or both and antioxidant and an anticorrosive agent.
64. A low noise small motor bearing according to claim 37 wherein said polymer ester oil is present in an amount of 20 to 50% by weight of said grease composition.
65. A low noise small motor bearing according to claim 37 wherein said polymer ester oil is present in a significant amount 20% or greater by weight of said base oil.
66. A low noise small motor bearing according to claim 37 wherein said polymer ester oil has a molecular weight of 1,000 to 3,000 and a viscosity (40°) of 100 to 1,000 mm2/s.
67. A low noise small motor bearing according to claim 45 wherein said polymer ester oil has a molecular weight of 1,000 to 3,000 and a viscosity (40°) of 100 to 1,000 mm2/s.
68. A low noise small motor bearing according to claim 45 wherein said synthetic ester oil is
a) a synthetic diester oil having the formula:

RCOOH(CH2)nCOOR′
(where R and R′ represent alkyl groups with 3 to 18 carbon atoms, and can be identical or different from each other, and n is 3 to 12.);
b) a synthetic trimester oil having the formula

R(CH2COOR′)3
(where R and R′ represent alkyl groups with 3 to 10 carbon atoms);
c) a synthetic tetraester oil having the formula

R(CH2COOR′)4
(where R and R′ represent alkyl groups with 3 to 10 carbon atoms); or
d) a synthetic neopentyl polyol ester oil.
69. A low noise small motor bearing according to claim 45 wherein said synthetic hydrocarbon oil is a poly-α-olefin oil or a polybutene and olefin copolymer, that has a viscosity (40° C.) of 20 to 100 mm2/s.
70. A low noise small motor bearing according to claim 45 wherein said synthetic ether oil is an alkyl diphenyl ether.
71. A low noise small motor bearing according to claim 70 wherein said synthetic ether oil is dialkyl diphenyl ether, monoalkyl diphenyl ether, or a mixture thereof.
72. A low noise small motor bearing according to claim 45 wherein said mineral oil is a paraffinic oil with a viscosity (40° C.) of 90 to 150 mm2/s.
73. An air conditioner comprising a motor; said motor having one or more bearing according to claim 37.
74. A blower for image equipment comprising;
a) motor;
b) said motor having one or more bearings made according to claim 37.
US11/659,045 2004-08-03 2005-08-01 Heat resistant lithium grease composition and a small motor reduced noise bearing Abandoned US20090029881A1 (en)

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JP2004-227306 2004-08-03
JP2004227306A JP4688447B2 (en) 2004-08-03 2004-08-03 Heat-resistant lithium grease composition for encapsulating small motor bearings
PCT/US2005/027542 WO2006017562A1 (en) 2004-08-03 2005-08-01 Heat resistant lithium grease composition and a small motor reduced noise bearing

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WO2006017562A1 (en) 2006-02-16
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JP2006045323A (en) 2006-02-16
CN100572510C (en) 2009-12-23

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