Lubricant composition for ball joint and ball joint

Abstract

A lubricant composition for ball joints exhibits excellently low friction not only at ordinary temperatures but also from higher to lower temperatures, and will not leak out of ball joints at higher temperatures. A ball joint has the lubricant composition sealed therein. The lubricant composition contains a base oil including a synthetic hydrocarbon oil, a thickener, and a fatty acid salt of a compound represented by the formula (1): R 1 —NH—R 2 —NH 2   (1) (R 1 : hydrocarbon group of C1 to C24; R 2 : alkylene group of C2 to C4).

What is claimed is:  
     
         1 . A lubricant composition for ball joints comprising: 
 a base oil comprising a synthetic hydrocarbon oil;    a thickener;    a fatty acid salt of a compound represented by the formula (1):    R 1 —NH—R 2 —NH 2   (1)    wherein R 1  stands for a hydrocarbon group having 1 to 24 carbon atoms, and R 2  stands for an alkylene group having 2 to 4 carbon atoms.    
     
     
         2 . The composition of  claim 1 , wherein said synthetic hydrocarbon oil is selected from the group consisting of copolymers of ethylene and propylene, copolymers of ethylene and α-olefin having 5 to 12 carbon atoms, polybutene, polyisobutene, polymers of α-olefin having 5 to 12 carbon atoms, and mixtures thereof.  
     
     
         3 . The composition of  claim 1 , wherein said thickener is selected from the group consisting of soap thickeners, urea thickeners, and mixtures thereof.  
     
     
         4 . The composition of  claim 1  comprising 10 to 87 wt % of said base oil, 3 to 30 wt % of said thickener, and 10 to 87 wt % of said fatty acid salt of a composition of formula (1), based on a total amount of said composition.  
     
     
         5 . The composition of  claim 1  further comprising an additive selected from the group consisting of a solid lubricant, an extreme pressure agent, an antioxidant, an oiliness agent, a rust inhibitor, a viscosity index improver, waxes, and mixtures thereof.  
     
     
         6 . A ball joint comprising a metal ball stud and a synthetic resin seat, wherein said ball joint has a composition of  claim 1  sealed therein.