Stable lubricant emulsion

Abstract

A stable lubricant emulsion composition for use in engine and gear applications is provided. The emulsion includes a base petroleum oil, an aqueous salt solution that functions as a friction/wear modifier, and a polymeric non-ionic surfactant composition having a hydrophilic-lipophilic balance value in the range of 2.5 to 7 and an average molecular weight in the range of 1,000 to 3,000. The surfactant composition may include a polyester surfactant, a PIB succinimide surfactant, a PIB amine surfactant, or a mixture thereof.

What is claimed is: 
     
         1 . A lubricant composition, said composition comprising a water-in-oil emulsion comprising:
 a base oil;   a friction modifier in the form of an aqueous salt solution; and   a polymeric dispersant in an amount effective to form a stable emulsion,
 wherein the dispersant has an average molecular weight in the range of 1,000 to 3,000 and a hydrophilic-lipophilic balance value in the range of 2.5 to 7. 
   
     
     
         2 . The lubricant composition of  claim 1 , wherein the dispersant has a hydrophilic-lipophilic balance value in the range of 4 to 6. 
     
     
         3 . The lubricant composition of  claim 1 , wherein the dispersant has an average molecular weight in the range of 1,000 to 2,000. 
     
     
         4 . The lubricant composition of  claim 1 , wherein the dispersant comprises a polyester surfactant, a PIB succinimide surfactant, a PIB amine surfactant, or a mixture thereof. 
     
     
         5 . The lubricant composition of  claim 1 , wherein the dispersant comprises a polyester surfactant mixed with a PIB succinimide surfactant. 
     
     
         6 . The lubricant composition of  claim 1 , wherein the dispersant comprises a polyester surfactant mixed with a PIB amine surfactant. 
     
     
         7 . The lubricant composition of  claim 1 , wherein the emulsion is stable for at least six weeks. 
     
     
         8 . A method for formulating a water-in-oil emulsion comprising: a base oil; a friction modifier in the form of an aqueous salt solution; and a polymeric dispersant having an average molecular weight in the range of 1,000 to 3,000 and having a hydrophilic-lipophilic balance value in the range of 2.5 to 7, said method comprising the steps of:
 adding the aqueous salt solution to the base oil;   adding the dispersant to the base oil and to the aqueous salt solution to form a mixture; and   mixing the mixture to form the emulsion, wherein the dispersant is added in an amount effective to form a stable emulsion.   
     
     
         9 . The method of  claim 8 , wherein the dispersant has a hydrophilic-lipophilic balance value in the range of 4 to 6. 
     
     
         10 . The method of  claim 8 , wherein the dispersant has an average molecular weight in the range of 1,000 to 2,000. 
     
     
         11 . The method of  claim 8 , wherein the dispersant comprises a polyester surfactant, a PIB succinimide surfactant, a PIB amine surfactant, or a mixture thereof. 
     
     
         12 . The method of  claim 8 , wherein the dispersant comprises a polyester surfactant mixed with a PIB succinimide surfactant. 
     
     
         13 . The method of  claim 8 , wherein the dispersant comprises a polyester surfactant mixed with a PIB amine surfactant. 
     
     
         14 . The method of  claim 8 , wherein the emulsion is stable for at least six weeks. 
     
     
         15 . A lubricant composition, said composition comprising a water-in-oil emulsion comprising:
 a base oil;   a friction modifier in the form of an aqueous salt solution; and   a polymeric dispersant in an amount effective to form a stable emulsion,
 wherein the dispersant has an average molecular weight in the range of 1,000 to 3,000 and a hydrophilic-lipophilic balance value in the range of 4 to 6, 
 wherein the dispersant comprises a polyester surfactant mixed with a PIB succinimide surfactant or a polyester surfactant mixed with a PIB amine surfactant, and 
 wherein the emulsion is stable for at least six weeks.