Grease composition

Abstract

A grease composition comprising a lubricant base oil and a metal dithiocarbamate represented by the formula (1): wherein R 1 to R 4 may be the same or different and each stands for a hydrocarbon group having 10 to 20 carbon atoms, and X stands for a metal or a metal-containing group. The composition has long life even when used at a high temperature, is not harmful to humans and the environment, and can give an extended anti-flaking life to the rolling bearing.

What is claimed is:  
     
         1 . A grease composition comprising a lubricant base oil and a metal dithiocarbamate represented by the formula (1):  
       
         
           
           
               
               
           
         
       
       wherein R 1  to R 4  are the same or different and each stands for a hydrocarbon group having 10 to 20 carbon atoms, and X stands for a metal or a metal-containing group.  
     
     
         2 . The grease composition of  claim 1  wherein R 1  to R 4  are the same or different and each stands for a hydrocarbon group having 12 to 20 carbon atoms.  
     
     
         3 . The grease composition of  claim 1  wherein R 1  to R 4  are the same or different and each stands for a group selected from the group consisting of a straight or branched decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group and icosyl group; a straight or branched decenyl group, undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, octadecenyl group, nonadecenyl group, and icosenyl group; a cyclopentyl group with one or more alkyl substituents each having 1 to 15 carbon atoms; a cyclohexyl group with one or more alkyl substituents each having 1 to 14 carbon atoms; a cycloheptyl group with one or more alkyl substituents each having 1 to 13 carbon atoms; naphthyl group; a phenyl group with one or more alkyl substituents each having 1 to 14 carbon atoms; and an alkyl group having a phenyl substituent and/or an alkylaryl substituent.  
     
     
         4 . The grease composition of  claim 1  wherein X is a metal selected from the group consisting of Mo, Zn, Pb, Sb, Cu and Ni.  
     
     
         5 . The grease composition of  claim 1  wherein X is a metal containing group represented by the formula (2):  
       
         
           
           
               
               
           
         
       
       wherein Y stands for a metal, and each of Z 1  to Z 4  independently stand for a oxygen atom or a sulfur atom.  
     
     
         6 . The grease composition of  claim 5  wherein Y stands for Mo, Zn, Pb, Sb, Cu and Ni.  
     
     
         7 . The grease composition of  claim 1  wherein the content of said metal dithiocarbamate is in a range of 0.05 wt % to 10 wt % with respect to the total amount of the grease composition.  
     
     
         8 . The grease composition of  claim 1  wherein kinematic viscosity of said base oil is in a range of 10 to 500 mm 2 /s at 40° C.  
     
     
         9 . The grease composition of  claim 1  further comprising a thickener.  
     
     
         10 . The grease composition of  claim 1  wherein said thickener comprises a compound selected from a urea compound, a urea-urethane compound, a urethane compound and mixtures thereof.  
     
     
         11 . The grease composition of  claim 10  wherein said thickener comprises one or more compounds represented by the following formula (3): 
       A—CONH—R 5 —NHCO—B  (3) 
       wherein R 5  stands for a divalent hydrocarbon group, A and B are the same or different and each stands for —NHR 6 , —NR 7 R 8  or —OR 9 , and R 6  to R 9  are the same or different and each stands for a hydrocarbon residue having 6 to 20 carbon atoms.