Cold-proof grease composition for reducing noise

Abstract

The invention provides a cold-proof grease composition for reducing noise. In certain embodiments, the invention provides a grease composition having an improved noise-reduction effect without sacrificing lubricant adhesiveness at high and low temperatures. In one embodiment, the grease composition comprises a synthetic hydrocarbon oil as a base oil, a lithium-based thickener, and a poly(methyl acrylate) (PMA)-based copolymer.

What is claimed is: 
     
         1 . A cold-proof grease composition for reducing noise comprising:
 50-75 wt % of a base oil comprising a synthetic hydrocarbon oil;   10-30 wt % of a poly(methyl acrylate) (PMA)-based copolymer; and   10-20 wt % of a lithium-based thickener.   
     
     
         2 . The cold-proof grease composition for reducing noise according to  claim 1 , wherein the synthetic hydrocarbon oil is an aliphatic hydrocarbon oil with a viscosity of 4-6 cSt at 100° C. 
     
     
         3 . The cold-proof grease composition for reducing noise according to  claim 2 , wherein the aliphatic hydrocarbon oil comprises poly-α-olefin (PAO) or a copolymer of α-olefin and olefin. 
     
     
         4 . The cold-proof grease composition for reducing noise according to  claim 1 , wherein the PMA-based copolymer is an asterisk type having a radial or star-shaped structure and has a dynamic viscosity of 500-800 cSt at 100° C. 
     
     
         5 . The cold-proof grease composition for reducing noise according to  claim 4 , wherein the PMA-based copolymer comprises a styrene-alkyl methacrylate copolymer or a styrene-alkyl methacrylate copolymer. 
     
     
         6 . The cold-proof grease composition for reducing noise according to  claim 1 , wherein the lithium-based thickener is obtained by reacting lithium hydroxide with 12-hydroxystearic acid or by reacting lithium hydroxide with a hydrogenated castor oil. 
     
     
         7 . The cold-proof grease composition for reducing noise according to  claim 1 , further comprising 3 parts by weight of the grease composition of one or more additive selected from a group consisting of an extreme pressure additive, an antioxidant, a corrosion inhibitor, a rust inhibitor, a metal deactivator and a viscosity index improver.