Grease composition for constant velocity joint

Abstract

A grease composition for a constant velocity joint is provided, which comprises a mineral oil as a base oil along with an alicyclic-aliphatic diurea thickener, a sulfur-ester-based additive, molybdenum dithiocarbamate (Mo-DTC), molybdenum dithiophosphate (Mo-DTP) and zinc dithiophosphate (Zn-DTP) as additives. The composition improves NVH performance by lowering a generated axial force and P.R. (plunging resistance) while increasing abrasion resistance.

1 . A grease composition for constant velocity joint comprising:
 (a) 75.0-88 wt % of a base oil;   (b) 7.0-10.0 wt % of a thickener comprising an aliphatic diurea and an alicyclic diurea in a mixing ratio of 1:2.2-1:2.4 by weight; and   (c) 3.6-15 wt % of an additive comprising a sulfur-ester-based additive, molybdenum dithiophosphate (Mo-DTP), molybdenum dithiocarbamate (Mo-DTC) and zinc dithiophosphate (Zn-DTP).   
     
     
         2 . The composition of  claim 1 , wherein the base oil is a mineral oil having a dynamic viscosity of 60-100 mm 2 /s at 40° C. 
     
     
         3 . The composition of  claim 1 , wherein the alicyclic diurea is a compound of the following Formula 1:
   R 1 NH—CO—NH—C 6 H 4 - p -CH 2 —C 6 H 4 - p -HN—CO—NHR 1   [Formula 1]   wherein R 1  is a C 6  cyclohexyl group.   
     
     
         4 . The composition of  claim 1 , wherein the aliphatic diurea is a compound of the following Formula 2:
   2,4-[R 2 NH—CO—NH] 2 —C 6 H 3 —CH 3   [Formula 2]   wherein R 2  is a C 18  oleyl group.   
     
     
         5 . The composition of  claim 1 , wherein the additive comprises 1.0-3.0 wt % of a sulfur-ester-based additive, 0.1-1.0 wt % of molybdenum dithiophosphate, 1.50-4.0 wt % of molybdenum dithiocarbamate, and 1.0-3.0 wt % of zinc dithiophosphate. 
     
     
         6 . The composition of  claim 1 , wherein the molybdenum dithiocarbamate is a compound of the following Formula 3:
   [R 3 R 4 N—CS—S] 2 —Mo 2 O m S n   [Formula 3]   wherein R 3  and R 4  are independently a C 1 -C 24  alkyl group; and m is an integer of 0-3 and n is an integer of 1-4 with m+n being 4.   
     
     
         7 . The composition of  claim 1 , wherein the molybdenum dithiophosphate is a compound of the following Formula 4: 
       
         
           
           
               
               
           
         
         wherein R 5 , R 6 , R 7  and R 8  are independently a C 1 -C 24  primary or secondary alkyl or a C 6 -C 30  aryl group.