Grease composition and method for preparing the same

Abstract

A grease composition includes a base oil, a thickener, and a styrene-based block copolymer containing ethylene-alpha olefin copolymerization repeating units as a first polymer additive, wherein 1.5% to 15% by weight of the first polymer additive is contained based on a total weight of the grease composition.

1 . A grease composition comprising:
 a base oil;   a thickener; and   a styrene-based block copolymer containing ethylene-alpha olefin copolymerization repeating units as a first polymer additive;   wherein 1.5% to 15% by weight of the first polymer additive is contained based on a total weight of the grease composition.   
     
     
         2 . The grease composition of  claim 1 , wherein the styrene-based block copolymer containing the ethylene-alpha olefin copolymerization repeating units includes at least one selected from a group consisting of a styrene-ethylene-propylene (SEP) copolymer, a styrene-ethylene-butylene (SEB) copolymer, a styrene-ethylene-butylene-styrene (SEBS) copolymer, and a styrene-ethylene⋅propylene-styrene block (SEPS) copolymer. 
     
     
         3 . The grease composition of  claim 1 , further comprising:
 at least one selected from a group consisting of an olefin copolymer (OCP), a hydrogenated styrene diblock copolymer (HSD), a polyethylene wax (PE wax), and a polypropylene wax (PP wax) as a second polymer additive.   
     
     
         4 . The grease composition of  claim 3 , wherein 1.5% to 15% by weight of the second polymer additive is contained based on the total weight of the grease composition. 
     
     
         5 . The grease composition of  claim 3 , wherein a weight ratio of the first polymer additive and the second polymer additive is 1 to 2:1. 
     
     
         6 . The grease composition of  claim 1 , wherein the base oil includes at least one selected from a group consisting of a petroleum oil, a silicone base oil, an aliphatic hydrocarbon oil, and an aromatic hydrocarbon oil. 
     
     
         7 . The grease composition of  claim 1 , wherein the thickener includes a lithium-based thickener. 
     
     
         8 . The grease composition of  claim 1 , wherein 60% to 90% by weight of the base oil is contained based on the total weight of the grease composition, and
 wherein 2% to 35% by weight of the thickener is contained.   
     
     
         9 . The grease composition of  claim 1 , further comprising:
 at least one selected from a group consisting of an extreme-pressure additive, an antioxidant, a corrosion inhibitor, an anti-wear agent, a metal deactivator, and a viscosity index improver as a general additive.   
     
     
         10 . The grease composition of  claim 9 , wherein 1% to 5% by weight of the general additive is contained based on the total weight of the grease composition. 
     
     
         11 . A method for preparing a grease composition, the method comprising:
 stirring a mixture of a base oil, a thickener, and a styrene-based block copolymer containing ethylene-alpha olefin copolymerization repeating units as a first polymer additive at a temperature in a range from 130° C. to 180° C.;   wherein a content of the first polymer additive in the mixture is 1.5% to 15% by weight based on a total weight of the mixture.   
     
     
         12 . The method of  claim 11 , wherein the styrene-based block copolymer containing the ethylene-alpha olefin copolymerization repeating units includes at least one selected from a group consisting of a styrene-ethylene-propylene (SEP) copolymer, a styrene-ethylene-butylene (SEB) copolymer, a styrene-ethylene-butylene-styrene (SEBS) copolymer, and a styrene-ethylene⋅propylene-styrene block (SEPS) copolymer. 
     
     
         13 . The method of  claim 11 , wherein the stirring includes:
 first mixing the base oil with the thickener; and   additionally mixing the styrene-based block copolymer containing the ethylene-alpha olefin copolymerization repeating units with the mixture obtained in the mixture of base oil and thickener.   
     
     
         14 . The method of  claim 11 , wherein the stirring includes:
 first mixing the base oil with the thickener;   performing a saponification reaction by adding Li to the mixture of base oil and thickener; and   additionally mixing the styrene-based block copolymer containing the ethylene-alpha olefin copolymerization repeating units with the mixture in which the saponification reaction was performed.   
     
     
         15 . The method of  claim 14 , wherein the saponification reaction is performed at a temperature in a range from 60° C. to 100° C. 
     
     
         16 . The method of  claim 11 , further comprising:
 cooling the mixture to 25° C.   
     
     
         17 . The method of  claim 11 , wherein the mixture further contains at least one selected from a group consisting of an olefin copolymer (OCP), a hydrogenated styrene diblock copolymer (HSD), a polyethylene wax (PE wax), and a polypropylene wax (PP wax) as a second polymer additive. 
     
     
         18 . The method of  claim 17 , wherein 1.5% to 15% by weight of the second polymer additive is contained based on the total weight of the mixture.