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
  • C10M169/06—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
  • 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
• • 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
  • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
  • C10M2201/06—Metal compounds
  • C10M2201/061—Carbides; Hydrides; Nitrides
• • 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
  • C10M2203/1006—Petroleum or coal fractions, e.g. tars, solvents, bitumen 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
  • C10M2205/028—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers containing aliphatic monomers having more than four carbon atoms
  • C10M2205/0285—Organic macromolecular hydrocarbon compounds or fractions, whether or not modified by oxidation as ingredients in lubricant compositions containing acyclic monomers containing aliphatic monomers having more than four carbon atoms 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
  • C10M2213/00—Organic macromolecular compounds containing halogen as ingredients in lubricant compositions
  • C10M2213/06—Perfluoro polymers
  • C10M2213/062—Polytetrafluoroethylene [PTFE]
• • 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
  • C10M2215/08—Amides
  • C10M2215/0813—Amides 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
  • 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
  • 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
  • C10M2215/221—Six-membered rings containing nitrogen and carbon only
  • C10M2215/222—Triazines
• • 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
  • C10N2020/011—Cloud point
• • 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
  • C10N2020/017—Specific gravity or density
• • 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
  • C10N2020/055—Particles related characteristics
  • C10N2020/06—Particles of special shape or size
• • 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
  • 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
  • C10N2040/04—Oil-bath; Gear-boxes; Automatic transmissions; Traction drives
• • 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
  • C10N2040/04—Oil-bath; Gear-boxes; Automatic transmissions; Traction drives
  • C10N2040/046—Oil-bath; Gear-boxes; Automatic transmissions; Traction drives for traction drives
• • 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
• • 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
  • C10N2070/00—Specific manufacturing methods for lubricant compositions

Definitions

• the invention relates to a grease composition that utilizes a urea-based thickener.
• Grease has been mainly used for slide bearings, rolling bearings, and sliding surfaces where it is difficult to maintain adhesion of a lubricant film due to the movement of the contact surface.
• urea-based grease that utilizes a urea-based thickener exhibits excellent water resistance, mechanical stability, and heat resistance, and has been widely used for metal-metal sliding parts at a low speed with a high load such as an automotive constant-velocity joint.
• a grease composition that comprises a base oil, an organomolybdenum compound (e.g., a molybdenum dialkyldithiocarbamate sulfide), a molybdenum disulfide, a zinc dithiophosphate compound, and an aliphatic amide has been proposed as a grease composition used for a constant-velocity joint (see PTL 1 to 3).
• the above grease composition is insufficient in terms of lubricity and particularly wear resistance, and shows a deterioration in wear resistance during long-term use at a high temperature.
• An object of the invention is to provide a grease composition that exhibits excellent lubricity, in particular excellent wear resistance, and shows only a small extent of deterioration in wear resistance with long-term use at high temperatures.
• the inventors of the invention conducted extensive studies in order to achieve the above object. As a result, the inventors found that, in comparison with a grease composition that is prepared by merely dispersing and mixing an amide compound powder into grease, a grease composition obtained by heating and melting an amide compound in the presence of a lubricant base oil forms a three-dimensional network structure of the amide holding the lubricant base oil therein to afford the grease composition significantly improved wear resistance and to show only a small extent of deterioration in wear resistance with long-term use under high temperatures.
• the invention was completed based on the above finding, and provides the following.
• the grease composition according to the invention exhibits excellent water resistance, mechanical stability, and heat resistance, provides excellent wear resistance to metal-metal sliding parts at a low speed with a high load, and shows only a small extent of deterioration in wear resistance with long-term use under high temperatures.
• the grease composition according to the invention comprises a lubricant base oil, an amide compound, a solid lubricant, and a urea-based thickener.
• a mineral oil-based lubricant base oil or a synthetic lubricant base oil may be used as the lubricant base oil used in connection with the invention. It is preferable to use a lubricant base oil having a kinematic viscosity of 1 to 1000 mm 2 /s, and more preferably 20 to 300 mm 2 /s at 40° C. If the kinematic viscosity (at 40° C.) of the lubricant base oil falls outside the range of 1 to 1000 mm 2 /s, it may be difficult to easily prepare a grease composition having the desired consistency.
• Examples of the mineral oil-based lubricant base oil include lubricant fractions obtained by distilling crude oil under atmospheric pressure optionally followed by distillation under reduced pressure to obtain a distillate, and refining the distillate using various types of refining process.
• Examples of the refining process include hydrotreating, solvent extraction, solvent dewaxing, hydrodewaxing, washing with sulfuric acid, clay treatment, and the like.
• the base oil used in connection with the invention can be obtained by combining these processes in an appropriate order. A mixture of a plurality of refined oils having different properties is also useful, wherein the mixture is obtained by using different types of crude oils or distillates and by a different combination and/or order of processes.
• the base oil obtained by each method may preferably be used as long as the properties of the base oil are adjusted to fall within the above ranges.
• the synthetic lubricant base oil examples include polyolefins such as a poly- ⁇ -olefin, a polybutene, and a copolymer of two or more olefins, polyesters, polyalkylene glycols, alkylbenzenes, alkylnaphthalenes, and the like. It is preferable to use a poly- ⁇ -olefin from the viewpoint of availability, cost, viscosity, oxidation stability, and compatibility with a system member. A polymer of 1-dodecene or 1-decene is more preferable as the poly- ⁇ -olefin from the viewpoint of cost.
• synthetic lubricant base oils may be used either alone or in combination.
• the synthetic lubricant base oil may be used in combination with the mineral oil-based lubricant base oil.
• each base oil When using a mixture of a plurality of types of lubricant base oil including a synthetic lubricant base oil, the properties of each base oil are not necessary to fall within the above ranges as long as the base oil mixture satisfies the above properties. Therefore, each synthetic base oil need not necessarily satisfy the above properties, but it is preferable that the properties of each synthetic base oil fall within the above ranges.
• the content of the lubricant base oil in the grease composition is preferably 50 to 95 mass %, and more preferably 60 to 85 mass %, based on the total amount of the grease composition. If the content of the lubricant base oil is outside the range of 50 to 95 mass %, it may be difficult to easily prepare a grease composition having the desired consistency.
• the amide compound used in connection with the invention is a monoamide that includes one amide group (—NH—CO—), a bisamide that includes two amide groups, a triamide that includes three amide groups, or the like.
• the bisamide and the triamide have an advantage in that the frictional resistance in the sliding part can be reduced even when the amide compound is used in a relatively small amount.
• the bisamide may be an acid amide of a diamine or an acid amide of a diacid.
• an amide compound having a melting point of 40 to 180° C. (more preferably 80 to 180° C., and still more preferably 100 to 170° C.) and a molecular weight of 242 to 932 (more preferably 298 to 876).
• the monoamide is represented by the following general formula (1)
• the bisamide is represented by the following general formulas (2) and (3)
• the triamide is represented by the following general formula (4).
• R 1 , R 2 , and R 3 are independently a hydrocarbon group having 5 to 25 carbon atoms.
• the hydrocarbon group may be an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group.
• R 2 in the general formula (1) may be a hydrogen atom.
• a 1 , A 2 , and A 3 are independently an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, or a divalent hydrocarbon group having 1 to 10 carbon atoms formed by combining these groups, and M is an amide group.
• R 2 is a hydrogen atom or a saturated or unsaturated chain hydrocarbon group having 10 to 20 carbon atoms when the amide compound is the monoamide.
• a 1 is a divalent saturated chain hydrocarbon group having 1 to 4 carbon atoms when the amide compound is the acid amide of a diamine.
• Some of the hydrogen atoms of the hydrocarbon group represented by R 1 , R 2 , or A 1 in the general formulas (2) and (3) may be substituted with a hydroxyl group (—OH).
• aliphatic amide An amide compound in which A 1 , A 2 , and A 3 are an aliphatic hydrocarbon group is referred herein to as “aliphatic amide”, an amide compound in which at least one of A 1 , A 2 , and A 3 is an aromatic hydrocarbon group is referred herein to as “aromatic amide”, and an amide compound in which at least one of A 1 , A 2 , and A 3 is an alicyclic hydrocarbon group or an aromatic hydrocarbon group is referred herein to as “non-aliphatic amide”.
• R 1 , R 2 , and R 3 is a saturated or unsaturated chain hydrocarbon group having 10 to 20 carbon atoms when the amide compound is the aliphatic amide.
• R 1 , R 2 , and R 3 is a saturated or unsaturated chain hydrocarbon group having 10 to 20 carbon atoms or an aromatic hydrocarbon group when the amide compound is the aromatic amide.
• the non-aliphatic amide may also be used as the amide compound, but it is preferable to use the aliphatic amide as the amide compound. It is preferable that A 1 is a divalent saturated chain hydrocarbon group having 1 to 4 carbon atoms when the amide compound is the acid amide of a diamine (general formula (3)).
• the monoamide examples include saturated fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide, unsaturated fatty acid amides such as oleic acid amide and erucic acid amide, substituted amides of a saturated or unsaturated long-chain fatty acid and a long-chain amine such as stearylstearic acid amide, oleyloleic acid amide, oleylstearic acid amide, and stearyloleic acid amide, and the like.
• saturated fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide
• unsaturated fatty acid amides such as oleic acid amide and erucic acid amide
• the acid amide of a diamine represented by the general formula (2) include ethylene bis-stearic acid amide, ethylene bis-isostearic acid amide, ethylene bis-oleic acid amide, methylene bis-lauric acid amide, hexamethylene bis-oleic acid amide, hexamethylene bis-hydroxystearic acid amide, and the like.
• Specific examples of the bisamide of a diacid represented by the general formula (3) include N,N′-bis-stearylsebacic acid amide and the like.
• the amide compounds represented by the general formula (2) or (3) in which R 1 and R 2 are independently a saturated chain hydrocarbon group or an unsaturated chain hydrocarbon group having 12 to 20 carbon atoms are preferable.
• N-acylamino acid diamide compound there are various triamide compounds that are represented by the general formula (4).
• Specific examples of a compound among the compounds represented by the general formula (4) that can be suitably used in connection with the invention include an N-acylamino acid diamide compound.
• the N-acyl group included in the N-acylamino acid diamide compound is preferably a linear or branched saturated or unsaturated aliphatic acyl group having 1 to 30 carbon atoms, or an aromatic acyl group in particular, a caproyl group, a capryloyl group, a lauroyl group, a myristoyl group, or a stearoyl group.
• the amino acid included in the N-acylamino acid diamide compound is preferably aspartic acid or glutamic acid.
• the amine of the amide group included in the N-acylamino acid diamide compound is preferably a linear or branched saturated or unsaturated aliphatic amine having 1 to 30 carbon atoms, and more preferably butylamine, octylamine, laurylamine, isostearylamine, or stearylamine.
• N-lauroyl-L-glutamic acid- ⁇ , ⁇ -di-n-butylamide is preferable.
• amide compounds may be used either alone or in combination.
• the content of the amide compound in the grease composition is preferably 0.1 to 50 mass %, and more preferably 3 to 35 mass %, based on the total amount of the grease composition.
• the solid lubricant is not particularly limited as long as the solid lubricant is normally used as a lubricant. It is preferable to use a layered compound or a fluororesin as the solid lubricant due to excellent lubricity.
• a compound having a layered crystal structure such as melamine cyanulate, boron nitride, graphite, mica, and fluorinated graphite is preferable as the layered compound. Note that it is undesirable to use a compound that includes a heavy metal or sulfur from the viewpoint of environmental pollution and the like.
• Examples of a preferable fluororesin include a polytetrafluoroethylene (PTFE), a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), a tetrafluoroethylene-hexafluoropropylene copolymer (FEP), a tetrafluoroethylene-ethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and the like.
• PTFE polytetrafluoroethylene
• PFA tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer
• FEP tetrafluoroethylene-hexafluoropropylene copolymer
• ETFE tetrafluoroethylene-ethylene copolymer
• PVDF polyvinylidene fluoride
• PCTFE polychlorotrifluoroethylene
• solid lubricants may be used either alone or in combination.
• a solid lubricant having an appropriate particle size may be selected depending on the application. It is preferable to use a solid lubricant having a particle size (diameter) of 0.2 to 50 ⁇ m, and more preferably 1 to 10 ⁇ m.
• the content of the solid lubricant in the grease composition is preferably 0.1 to 10 mass %, and more preferably 0.2 to 5 mass %, based on the total amount of the grease composition.
• a diurea compound obtained by reacting a diisocyanate with a monoamine, a polyurea compound obtained by reacting a diisocyanate with a monoamine and a diamine, or the like may be used as the urea-based thickener.
• Examples of a preferable diisocyanate include phenylene diisocyanate, tolylene diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, and the like.
• Examples of a preferable monoamine include octylamine, dodecylamine, hexadecylamine, stearylamine, oleylamine, aniline, p-toluidine, cyclohexylamine, and the like.
• Examples of a preferable diamine include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylenediamine, diaminodiphenylmethane, and the like.
• urea-based thickeners may be used either alone or in combination.
• the content of the urea-based thickener in the grease composition may be appropriately determined as long as the desired consistency can be obtained.
• the content of the urea-based thickener in the grease composition is preferably 2 to 30 mass %, and more preferably 5 to 20 mass %, based on the total amount of the grease composition.
• the grease composition according to the invention may optionally include a detergent, a dispersant, an antiwear agent, a viscosity index improver, an antioxidant, an extreme pressure agent, a rust-preventive agent, a corrosion inhibitor, and the like that are normally used for a lubricant or grease in addition to the above components.
• the grease composition according to the invention may be prepared using a normal grease preparation method. It is preferable to heat a mixture comprising the amide compound to a temperature equal to or higher than the melting point of the amide compound at least once, after mixing the amide compound.
• the grease composition may be prepared by heating the amide compound and the lubricant base oil to a temperature equal to or higher than the melting point of the amide compound, cooling the mixture, and then physically mixing the cooled mixture with normal grease that comprises the solid lubricant, the thickener, and the lubricant base oil.
• all of the components including the urea-based thickener may be mixed, heated to a temperature equal to or higher than the melting point of the amide compound, and then cooled.
• the lubricant base oil When the amide compound is heated to a temperature equal to or higher than the melting point of the amide compound in the presence of at least the lubricant base oil, the lubricant base oil is held in a semi-solid gel state by the amide compound that forms a three-dimensional network structure, but freely moves within the network structure microscopically.
• the liquid lubricant base oil can move into the small voids from the gel due to a capillary phenomenon, or suggests that, when an excess liquid lubricant base oil is present in the system, the excess liquid lubricant base oil is incorporated in the gel due to a capillary phenomenon through the three-dimensional structure of the gel, for example.
• the urea-based thickener provides consistency in such a state.
• the grease composition thus exhibits excellent water resistance, mechanical stability, and heat resistance, provides excellent wear resistance, and shows only a small extent of deterioration in wear resistance with long-term use under high temperatures.
• the average particle size was measured by laser diffractometry.
• Diphenylamine was added to each composition as an antioxidant.
• Each component was charged in a vessel in the amount (wt %) shown in Table 1 or 2, heated to 150° C., which is a temperature equal to or higher than the melting point of the amide, stirred using a magnetic stirrer, and then cooled to room temperature.
• the mixture was dispersed under pressure using a roller (triple roll) to prepare a grease composition.
• a friction test was performed at a load of 350 lbf for 15 minutes using a FALEX Pin and Vee Block tester to evaluate the amount of wear of the sample.
• the FALEX test was also performed using a flesh grease and a degraded grease that is obtained by leaving the flesh grease at 150° C. for 100 hours or 500 hours.
• the grease composition according to the invention exhibits excellent water resistance, mechanical stability, and heat resistance, provides excellent wear resistance to metal-metal sliding parts at a low speed with a high load, and shows only a small extent of deterioration in wear resistance with long-term use under high temperatures
• the grease composition can be used to lubricate a joint, a gear, and a bearing, and the like that have metal-metal sliding parts.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Organic Chemistry (AREA)
• Lubricants (AREA)

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Cited By (9)

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Citations (2)

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• 2012
  • 2012-03-05 JP JP2012047750A patent/JP5931510B2/ja active Active
• 2013
  • 2013-03-01 EP EP13757298.8A patent/EP2824167B1/en active Active
  • 2013-03-01 SG SG11201404818TA patent/SG11201404818TA/en unknown
  • 2013-03-01 CN CN201380012569.3A patent/CN104160006A/zh active Pending
  • 2013-03-01 KR KR1020147027505A patent/KR102051688B1/ko active IP Right Grant
  • 2013-03-01 WO PCT/JP2013/055624 patent/WO2013133149A1/ja active Application Filing
  • 2013-03-01 US US14/382,851 patent/US20150024981A1/en not_active Abandoned

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