Grease composition

Abstract

The invention provides a grease composition for rolling bearings of automotive electrical equipment or automotive auxiliaries, where a base oil contains as an essential component an alkyldiphenyl ether oil; a thickener is a diurea compound represented by the following formula (1): (wherein R 2 is a diphenylmethane group; and R 1 and R 3 , which may be the same or different represent an aromatic hydrocarbon group having 6 to 12 carbon atoms); and an anti-flaking additive that contains an organic sulfonate rust inhibitor and a load carrying additive. The grease composition of the invention can extend the bearing lubrication life even at elevated temperatures and exhibit excellent anti-flaking properties, so that the grease composition can be enclosed in the rolling bearings of automotive electrical equipment or automotive auxiliaries.

1 . A grease composition for rolling bearings of automotive electrical equipment or automotive auxiliaries, comprising:
 a base oil that comprises as an essential component an alkyldiphenyl ether oil;   as a thickener, a diurea compound represented by the following formula (1):   
       
         
           
           
               
               
           
         
         wherein R 2  is a diphenylmethane group; and R 1  and R 3 , which may be the same or different represent an aromatic hydrocarbon group having 6 to 12 carbon atoms; and 
         as an anti-flaking additive, an organic sulfonate rust inhibitor and a load carrying additive. 
       
     
     
         2 . The grease composition for rolling bearings of  claim 1 , wherein the organic sulfonate rust inhibitor is represented by formula (2):
   [R 4 —SO 3 ]nM  Formula (2)
   
       wherein R 4  is an alkyl group, alkenyl group, alkylnaphthyl group, dialkylnaphthyl group, alkylphenyl group or residual group of high-boiling petroleum fraction, wherein the alkyl group or alkenyl group is a straight-chain or branched group having 2 to 22 carbon atoms; M is an alkali metal, alkaline earth metal, zinc or ammonium ion; and n is a valence number of M. 
     
     
         3 . The grease composition of  claim 1 , wherein the organic sulfonate rust inhibitor is at least one selected from the group consisting of zinc salts and calcium salts. 
     
     
         4 . The grease composition of  claim 1 , wherein the load carrying additive is at least one selected from the group consisting of thiocarbamates, thiophosphates, naphthenates, carboxylates, and organic phosphate esters. 
     
     
         5 . The grease composition of  claim 1 , wherein the load carrying additive is at least one selected from the group consisting of thiocarbamates and thiophosphates. 
     
     
         6 . The grease composition of  claim 1 , further comprising an amine type antioxidant and a phenol type antioxidant as antioxidants. 
     
     
         7 . A rolling bearing for automotive electrical equipment or automotive auxiliaries, wherein the grease composition of  claim 1  is enclosed. 
     
     
         8 . The grease composition of  claim 2 , wherein the organic sulfonate rust inhibitor is at least one selected from the group consisting of zinc salts and calcium salts. 
     
     
         9 . The grease composition of  claim 8 , wherein the load carrying additive is at least one selected from the group consisting of thiocarbamates, thiophosphates, naphthenates, carboxylates, and organic phosphate esters. 
     
     
         10 . The grease composition of  claim 9 , wherein the load carrying additive is at least one selected from the group consisting of thiocarbamates and thiophosphates. 
     
     
         11 . The grease composition of  claim 10 , further comprising an amine type antioxidant and a phenol type antioxidant as antioxidants. 
     
     
         12 . A rolling bearing for automotive electrical equipment or automotive auxiliaries, wherein the grease composition of  claim 11  is enclosed.