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
  • C10M141/00—Lubricating compositions characterised by the additive being a mixture of two or more compounds covered by more than one of the main groups C10M125/00 - C10M139/00, each of these compounds being essential
  • C10M141/10—Lubricating compositions characterised by the additive being a mixture of two or more compounds covered by more than one of the main groups C10M125/00 - C10M139/00, each of these compounds being essential at least one of them being an organic phosphorus-containing compound
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  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M117/00—Lubricating compositions characterised by the thickener being a non-macromolecular carboxylic acid or salt thereof
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  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M119/00—Lubricating compositions characterised by the thickener being a macromolecular compound
  • C10M119/24—Lubricating compositions characterised by the thickener being a macromolecular compound containing nitrogen
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  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M125/00—Lubricating compositions characterised by the additive being an inorganic material
  • C10M125/22—Compounds containing sulfur, selenium or tellurium
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  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M135/00—Lubricating compositions characterised by the additive being an organic non-macromolecular compound containing sulfur, selenium or tellurium
  • C10M135/12—Thio-acids; Thiocyanates; Derivatives thereof
  • C10M135/14—Thio-acids; Thiocyanates; Derivatives thereof having a carbon-to-sulfur double bond
  • C10M135/18—Thio-acids; Thiocyanates; Derivatives thereof having a carbon-to-sulfur double bond thiocarbamic type, e.g. containing the groups
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  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M137/00—Lubricating compositions characterised by the additive being an organic non-macromolecular compound containing phosphorus
  • C10M137/02—Lubricating compositions characterised by the additive being an organic non-macromolecular compound containing phosphorus having no phosphorus-to-carbon bond
  • C10M137/04—Phosphate esters
  • C10M137/10—Thio derivatives
• • 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
  • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
  • C10M2201/06—Metal compounds
  • C10M2201/065—Sulfides; Selenides; Tellurides
• • 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
  • C10M2201/065—Sulfides; Selenides; Tellurides
  • C10M2201/066—Molybdenum sulfide
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2201/00—Inorganic compounds or elements as ingredients in lubricant compositions
  • C10M2201/08—Inorganic acids or salts thereof
  • C10M2201/084—Inorganic acids or salts thereof containing sulfur, selenium or tellurium
• • C—CHEMISTRY; METALLURGY
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  • 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
  • C10M2207/106—Carboxylix acids; Neutral salts 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
  • C10M2207/1206—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to acyclic or cycloaliphatic carbon atoms used as thickening agents
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  • 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
• • 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
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  • 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
  • C10M2207/14—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to carbon atoms of six-membered aromatic rings
  • C10M2207/1406—Carboxylix acids; Neutral salts thereof having carboxyl groups bound to carbon atoms of six-membered aromatic rings 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
  • C10M2207/26—Overbased carboxylic acid salts
  • C10M2207/2613—Overbased carboxylic acid salts 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
  • C10M2207/26—Overbased carboxylic acid salts
  • C10M2207/262—Overbased carboxylic acid salts derived from hydroxy substituted aromatic acids, e.g. salicylates
  • C10M2207/2626—Overbased carboxylic acid salts derived from hydroxy substituted aromatic acids, e.g. salicylates 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
  • C10M2215/02—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
  • C10M2217/00—Organic macromolecular compounds containing nitrogen as ingredients in lubricant compositions
  • C10M2217/04—Macromolecular compounds from nitrogen-containing monomers obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • C10M2217/044—Polyamides
• • 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
  • C10M2217/00—Organic macromolecular compounds containing nitrogen as ingredients in lubricant compositions
  • C10M2217/04—Macromolecular compounds from nitrogen-containing monomers obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • C10M2217/045—Polyureas; Polyurethanes
• • 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
  • C10M2219/06—Thio-acids; Thiocyanates; Derivatives thereof
  • C10M2219/062—Thio-acids; Thiocyanates; Derivatives thereof having carbon-to-sulfur double bonds
  • C10M2219/066—Thiocarbamic type compounds
• • 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
  • C10M2219/06—Thio-acids; Thiocyanates; Derivatives thereof
  • C10M2219/062—Thio-acids; Thiocyanates; Derivatives thereof having carbon-to-sulfur double bonds
  • C10M2219/066—Thiocarbamic type compounds
  • C10M2219/068—Thiocarbamate metal salts
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2223/00—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions
  • C10M2223/02—Organic non-macromolecular compounds containing phosphorus as ingredients in lubricant compositions having no phosphorus-to-carbon bonds
  • C10M2223/04—Phosphate esters
  • C10M2223/045—Metal containing thio derivatives
• • 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
  • C10N2010/02—Groups 1 or 11
• • 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
  • C10N2010/00—Metal present as such or in compounds
  • C10N2010/12—Groups 6 or 16

Definitions

• the present invention relates to lubricating compositions, particularly to lubricating greases containing such compositions, and more particularly to lubricating greases for use in constant velocity joints of all types, e.g. to constant velocity fixed ball joints and to the plunging type constant velocity joint.
• the primary purpose of lubrication is separation of solid surfaces moving relative to one another, to minimise friction and wear.
• the materials most frequently used for this purpose are oils and greases.
• the choice of lubricant is mostly determined by the particular application.
• Lubricating greases are employed where heavy pressures exist, where oil drip from the bearings is undesirable or where the motion of the contacting surfaces is discontinuous so that it is difficult to maintain a separating film in the bearing. Because of design simplicity, decreased sealing requirements and less need for maintenance, greases are almost universally given first consideration for lubricating ball and roller bearings in electric motors, household appliances, automotive wheel bearings, machine tools or aircraft accessories. Greases are also used for the lubrication of small gear drives and for many slow- speed sliding applications.
• Lubricating greases consist primarily of a fluid lubricant, such as an oil, and a thickener. Essentially, the same type of oil is employed in compounding a grease as would normally be selected for oil lubrication.
• Fatty acid soaps of lithium, calcium, sodium, aluminium and barium are most commonly used as thickeners.
• thickeners may be one of a variety of solid materials, including clays, soaps and complexes such as those of lithium, and urea-type compounds .
• the base oil may be of mineral or synthetic origin. Base oils of mineral origin may be mineral oils, for example produced by solvent refining or hydro- processing. Base oils of synthetic origin may typically be mixtures of hydrocarbon polymers, for example liquid polymers of alpha-olefins .
• the base oil may also be a mixture of these oils.
• the base oil is that of mineral origin sold by the Royal Dutch/Shell Group of Companies under the designations "HVI” or "MVIN”, is a polyalphaolefin, or is a mixture of the two.
• Synthetic hydrocarbon base oils for example those sold by the Royal Dutch/Shell Group of Companies under the designation "XHVI” (trade mark) may also be used.
• a lubricating grease preferably contains 5 to 20% by weight of thickener.
• Lithium soap thickened greases have been known for many years.
• the lithium soaps are derived from C ⁇ _o-2 / preferably Ci5_ ⁇ _g, saturated or unsaturated fatty acids or derivatives thereof.
• One particular derivative is hydrogenated castor oil, which is the glyceride of 12-hydroxystearic acid.
• 12-Hydroxystearic acid is a particularly preferred fatty acid.
• Greases thickened with complex thickeners are well known.
• a complexing agent is incorporated into the thickener, which is commonly a low to medium molecular weight acid or dibasic acid or one of its salts, such as benzoic acid or boric acid or a lithium borate.
• Urea compounds used as thickeners in greases include the urea group (-NHCONH-) in their molecular structure. These compounds include mono-, di- or polyurea compounds, depending upon the number of urea linkages.
• Zinc dithiocarbamates are sometimes used as antioxidants and also as corrosion inhibitors in some lubricants such as diesel and gasoline engine oils and industrial oils.
• Molybdenum disulphide (a non-organic molybdenum compound) is a known highly wear resistant solid lubricant and is used in a wide variety of lubricants.
• MoDTC molybdenum dithiophosphates
• ZnDTP zinc dialkyl dithiophosphate
• Molybdenum disulphide thought by some to be such a decomposition product, was tested in a reference grease thickened with a lithium 12-hydroxy stearate soap and containing 0.5% mass zinc dibutyl dithiocarbamate as an oxidation inhibitor.
• the resulting grease exhibited high (i.e. undesirable) friction and only moderate anti-wear properties; zinc compounds tested separately in the same reference grease also showed no reduced friction.
• a friction reducing additive combination comprising molybdenum disulphide, zinc naphthenate and metal dithiophosphate optionally in combination with metal dithiocarbamates.
• Example 22 it is shown that the presence of zinc naphthenate is essential.
• molybdenum disulphide, zinc dithiocarbamate and a metal dithiophosphate in combination work synergistically as a friction reducing agent in lubricating compositions, especially greases, whilst retaining good, low anti- wear properties.
• zinc naphthenate does not need to be present in this combination. Furthermore such combination is not thickener dependent. Tested against the use of molybdenum disulphide alone or in combination with one of the two other components, the friction reduction is shown to be quite unexpected.
• the present invention accordingly provides a lubricating composition which comprises a base oil of mineral and/or synthetic origin and a combination of molybdenum disulphide, one or more zinc dithiocarbamates and one or more metal dithiophosphates which composition contains no substantial amount of zinc naphthenate.
• the composition of the present invention contains no substantial amount of zinc naphthenate. This means that the composition contains less than 0.3% by weight of zinc naphthenate, based on total weight of lubricating composition.
• the amount of zinc naphthenate is the amount of compound per se, excluding further compounds which may be present in a commercial product e.g. mineral oil.
• the composition preferably contains less than 0.05% by weight of zinc naphthenate, more preferably less than 0.01% wt . Most preferably, the composition does not contain zinc naphthenate.
• Preferred is the use of the friction reducing additive combination in a lubricating grease which comprises a base oil of mineral and/or synthetic origin and a thickener, which is preferably a lithium soap, either simple or complex, or a urea compound.
• Such a lubricating grease preferably contains molybdenum disulphide in an amount of from 0.5 to 10% by weight, more preferably 1 to 4% by weight.
• the grease preferably contains zinc dithiocarbamate in an amount of from 0.01 to 5% by weight, more preferably 0.3 to 2.4% by weight, for a urea thickened grease and a complex lithium soap thickened greases, and an amount of from 0.5 to 10% by weight, more preferably 1 to 4% by weight, for a simple lithium soap thickened grease.
• a lubricating grease of the invention further preferably contains said one or more metal dithiophosphates in a total amount of from 0.15 to 10% by weight; more preferably 1 to 3% by weight. All amounts are based on total weight of the grease composition.
• the three components are present in an interrelated or 3-way proportion such that, for a urea thickened grease and for a complex lithium soap thickened grease the weight ratio of molybdenum disulphide to metal dithiophosphate is in the range of from 1:0.15 to 1:1, the weight ratio of metal dithiophosphate to zinc dithiocarbamate is in the range of from 1:0.25 to 1:1.5, and the weight ratio of molybdenum disulphide to zinc dithiocarbamate is in the range of from 1:0.4 to 1:1.5.
• the weight ratio of molybdenum disulphide to metal dithiophosphate preferably is in the range of from 1:0.15 to 1:1, the weight ratio of metal dithiophosphate to zinc dithiocarbamate is in the range of from 1:1 to 1:4.5 and the weight ratio of molybdenum disulphide to zinc dithiocarbamate is in the range of from 1:0.4 to 1:1.5.
• the one or more metal dithiophosphates is/are selected from zinc dialkyl-, diaryl- or alkylaryl-dithiophosphates
• the one or more zinc dithiocarbamates is/are selected from zinc dialkyl-, diaryl- or alkylaryl-dithiocarbamates, in which dithiophosphates and/or dithiocarbamates usefully any alkyl moiety is straight chain or branched and preferably contains from 1 to 12 carbon atoms.
• the thickener of lubricating greases preferably comprises a urea compound, a simple lithium soap or a complex lithium soap.
• a preferred urea compound is a polyurea compound.
• Such thickeners are well known in lubricant grease technology. Surprisingly effective compositions of the invention use simple lithium soaps as thickeners.
• Lubricating compositions of the invention may be prepared by incorporating the additive combination into a base oil in conventional manner. For greases this may be via hot or cold mixing followed by homogenisation to ensure uniform dispersion of the additive components. Other additives, e.g. antioxidants, may be included if necessary or desired.
• a method of lubricating a constant velocity joint comprising packing it with a lubricating grease according to the present invention.
• a constant velocity joint packed with a lubricating grease according to the present invention there is still further provided.
• Example 1 The present invention will now be described by reference to the following Examples, in which all percentages are given by weight.
• Example 1
• a lithium soap grease was prepared by adding a slurry of 1.12% w LiOH.F ⁇ O and water in the proportions of 1 part LiOH.I ⁇ O to 5 parts water to 9.15% w hydrogenated castor oil fatty acid in cold base oil (a blend of MVIN and HVI oils) and heating the mix in a sealed autoclave to 150°C. The steam was vented off and heating continued to 220°C before the reaction mass was quick cooled (at a rate of 6 to 7°C per minute) and the product homogenised. Additives were incorporated into the grease. In all cases, as antioxidant, 0.5% w of an aromatic amine was used.
• a grease of the present invention and a number of comparison greases were prepared and tested.
• the amount of molybdenum disulphide, ZnDTC (zinc diamyl dithiocarbamate) and ZnDTP (4-methyl-2-pentyl zinc dithiophosphate) was varied as shown in Table 1.
• the friction coefficient and wear scar diameter were evaluated for each grease; the results are also given in Table 1.
• the friction and wear measurements were made using an oscillating SRV friction tester.
• the oscillating SRV friction tester (from Optimol Instruments) was used with a 10 mm ball on a flat lapped surface as test geometry. An oscillation frequency of 50 Hertz and a stroke of 1.5 mm was used throughout. The friction coefficient was recorded after two hours of operation under the test conditions of a load of 300 Newtons at a temperature of 100°C.
• Wear was assessed by measuring the diameter of the wear scar on the ball at the end of the two hour test using an optical graticule.
• a grease of the present invention was compared with lithium greases having only molybdenum disulphide or molybdenum disulphide plus zinc dithiocarbamate or molybdenum disulphide plus zinc dithiophosphate all with the same base grease plus thickener plus antioxidant. It can be clearly seen from the results that the grease of the present invention has a significantly lower friction coefficient and wear scar diameter than any of the comparison greases.
• Example 2
• a urea grease C was prepared by heating 5% w of 4, 4 '-diphenylmethane diisocyanate in base oil (a mixture of 75% w HVI 160B and 25% w HVI 650) to 70°C and then adding 10.8% w stearylamine . The mixture was then further heated to 150°C before being cooled to 80°C. The other additives to be included in the formulation were then added. The formulated grease was then homogenised at ambient temperature.
• a grease of the present invention and a number of comparison greases were prepared and tested. Again in all cases, an antioxidant, 0.5% w of an aromatic amine, was added and for each grease the amount of molybdenum disulphide, ZnDTC (zinc diamyl dithiocarbamate) and ZnDTP (4-methyl-2-pentyl zinc dithiphosphate) were varied. The friction coefficient and wear for each grease was evaluated as in Example 1. Results are given in Table 2.
• a lithium complex grease was prepared by adding a 50%w slurry of LiOH.H0 and boric acid in water to hydrogenated castor oil fatty acid, calcium alkyl salicylate, and calcium octoate, in conventional proportions, in base oil, (a mixture of HVI oils) together with conventional antioxidants, and then heating the charge to 210°C with stirring. After slowly cooling the mixture to 160°C a quinoline and a hydroxyphenyl were added as additional antioxidants.
• the grease obtained contained 3% w molybdenum disulphide, 1.5% w ZnDTC and 1.5% w ZnDTP as friction reducing additive.

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