Grease composition for use in constant velocity joints comprising at least two different molybdenum compounds

Abstract

In order to provide for a grease composition reducing or preventing noise, vibration and harshness (NVH) in the driveline, a grease composition for use in constant velocity joints is suggested, comprising a) a base oil composition; b) at least one tri-nuclear molybdenum compound of the formula MO 3 S k L n Q Z , wherein L are independently selected ligands having organo groups with a sufficient number of carbon atoms to render the compound soluble or dispersible in the oil, n is from 1 to 4, k varies from 4 though 7, Q is selected from the group of neutral electron donating compounds such as amines, alcohols, phosphines, and ethers, and z ranges from 0 to 5 and includes non-stoichiometric values. c) at least one further molybdenum containing compound; and d) at least one simple and/or complex soap thickener.

1 . A grease composition for use in constant velocity joints comprising:
 a) a base oil composition;   b) at least one tri-nuclear molybdenum compound of the formula
   Mo 3 S k L n Q z , 
    wherein L are independently selected ligands having organo groups with a sufficient number of carbon atoms to render the compound soluble or dispersible in the oil, n is from 1 to 4, k varies from 4 though 7, Q is selected from the group of neutral electron donating compounds consisting of amines, alcohols, phosphines, and ethers, and z ranges from 0 to 5 and includes non-stoichiometric values.   c) at least one further molybdenum containing compound; and   d) at least one selected from the group consisting of a simple soap thickener and a complex soap thickener.   
   
   
       2 . A grease composition according to  claim 1 , characterised in that the further molybdenum containing compound is at least one selected from the group consisting of molybdenum dithiocarbamates and molybdenum dithiophosphates. 
   
   
       3 . A grease composition according to  claim 1 , comprising as a further molybdenum compound 0.3% by weight to 3% by weight of at least one selected from the group consisting of molybdenum dithiophosphate (MoDTP) and molybdenum dithiocarbamate (MoDTC), in each case referred to the total amount of the grease composition. 
   
   
       4 . A grease composition according to  claim 1 , characterised in that the soap thickener is at least one selected from the group consisting of Lithium soaps and Calcium soaps. 
   
   
       5 . A grease composition according to  claim 1 , further comprising at least one zinc dithiophosphate additive (ZnDTP). 
   
   
       6 . A grease composition according to  claim 1 , further comprising 0.3% by weight to 3% by weight of at least one zinc dithiophosphate additive (ZnDTP), referred to the total amount of the grease composition. 
   
   
       7 . A grease composition according to  claim 1 , further comprising an additive package including at least one selected from the group consisting of anti-oxidation agents, corrosion inhibitors, anti-wear agents, friction modifiers and extreme pressure agents (EP agents). 
   
   
       8 . A grease composition according to  claim 1 , comprising 50% by weight to 98% by weight of the base oil composition, 0.1% by weight to 5% by weight of at least one tri-nuclear molybdenum compound, 0.3% by weight to 2% by weight of at least one further molybdenum compound, and 1% by weight to 25% by weight of at least one soap thickener, in each case referred to the total amount of the grease composition. 
   
   
       9 . A grease composition according to  claim 1 , characterised in that the amount of the tri-nuclear molybdenum compounds present in the composition is in a range of between 0.3% by weight to 3% by weight, in each case referred to the total amount of the grease composition. 
   
   
       10 . A grease composition according to  claim 1 , characterised in that the weight percent added, referred to the total amount of the grease composition, of tri-nuclear molybdenum compounds is essentially identical with the weight percent of one selected from the group consisting of molybdenum dithiophosphates, molybdenum dithiocarbamates, or zinc dithiophosphates added. 
   
   
       11 . A grease composition according to  claim 1 , further comprising an addition of at least one selected from the group consisting of Ca-sulphonate grease in an amount from 0.1% by weight to 10% by weight and at least one sulphur containing extreme pressure agent in an amount from 0.1% by weight to 3% by weight in each case referred to the total amount of the grease composition. 
   
   
       12 . A grease composition according to  claim 1 , characterised in that the sliding friction coefficient of said composition is at most 0.8.