Lubricating oil composition containing alkali metal borates with improved frictional properties

Abstract

A lubricating oil composition with improved frictional and wear performance, especially when the ratio of polysulfides is controlled, wherein said composition comprises a major amount of an oil of lubricating viscosity, at least one alkali metal borate; at least one dihydrocarbyl polysulfide component comprising a mixture of sulfides and having at least 30% dihydrocarbyl tetrasulfide or higher sulfides; at least one non-acidic phosphorus component comprised of a trihydrocarbyl phosphite; at least one dihydrocarbyl dithiophosphate; and a phosphorus component comprising a dihydrocarbyl phosphite component is disclosed.

1 . A lubricating oil composition comprising an oil of lubricating viscosity having dispersed therein a minor amount of a mixture of:
 (a) at least one hydrated alkali metal borate component;   (b) at least one dihydrocarbyl polysulfide component comprising a mixture including less than about 64.5 wt. % dihydrocarbyl trisulfide, greater than about 5.5 wt. % dihydrocarbyl disulfide, and at least about 30.0 wt. % dihydrocarbyl tetrasulfide or higher polysulfides;   (c) at least one non acidic phosphorus component comprising a trihydrocarbyl phosphite component, at least 90 wt. % of which has the formula (RO) 3 P, wherein R is a hydrocarbyl group having 4 to 24 carbon atoms; and   (d) at least one dihydrocarbyl dithiophosphate.   
     
     
         2 . The composition of  claim 1  wherein said lubricating oil composition also contains a minor amount of dihydrocarbyl hydrogen phosphite, at least 90 wt. % of which has the formula (RO) 2 POH, wherein R is a hydrocarbyl group having 4 to 24 carbon atoms. 
     
     
         3 . The composition of  claim 1  wherein said lubricating oil composition comprises:
 (a) 0.1 to 20.0 wt. % alkali metal borate;   (b) 0.1 to 10.0 wt. % the dihydrocarbyl polysulfide component;   (c) 0.01 to 15.0 wt. % of a non-acidic phosphorus component; and   (d) 0.03 to 310 wt % of the dihydrocarbyl dithiophosphate.   
     
     
         4 . The composition of  claim 1 , wherein said alkali metal borate is a potassium or sodium triborate. 
     
     
         5 . The composition of  claim 1 , wherein said trihydrocarbyl phosphite is a mixture of C 10  to C 20  trialkyl phosphites. 
     
     
         6 . The composition of  claim 1 , wherein said dihydrocarbyl dithiophosphate is an amine dithiophosphate salt. 
     
     
         7 . A gear oil additive package comprising a mixture of:
 (a) a hydrated alkali metal borate component;   (b) a dihydrocarbyl polysulfide component comprising a mixture including less than about 64.5 wt. % dihydrocarbyl trisulfide, greater than about 5.5 wt. % dihydrocarbyl disulfide and at least about 30.0 wt. % dihydrocarbyl tetrasulfide or higher polysulfides;   (c) a non-acidic phosphorus component comprising a trihydrocarbyl phosphite component at least 90 wt. % of which has the formula (RO) 3 P, where R is a hydrocarbyl of 4 to 24 carbon atoms, and   (d) at least one dihydrocarbyl dithiophosphate.   
     
     
         8 . A gear oil additive package comprising a mixture of:
 (a) a hydrated alkali metal borate component;   (b) a dihydrocarbyl polysulfide component comprising a mixture including less than 70 wt. % dihydrocarbyl trisulfide, more than 5.5 wt. % dihydrocarbyl disulfide, and at least 30 wt. % dihydrocarbyl tetrasulfide or higher polysulfides;   (c) a non-acidic phosphorus component comprising a trihydrocarbyl phosphite component, at least 90 wt. % of which has the formula (RO) 3 P, where R is a hydrocarbyl group of 4 to 24 carbon atoms;   (d) at least one dihydrocarbyl dithiophosphate; and   (e) a phosphorus component comprising a dihydrocarbyl phosphite component at least 90 wt. % of which has the formula (RO) 2 POH, where R is alkyl of 4 to 24 carbon atoms.   
     
     
         9 . A lubricating oil composition comprising a major amount of lubricating oil and a minor but effective amount of the gear oil additive package of  claim 7  to improve the load carrying and frictional properties of the lubricating composition. 
     
     
         10 . A lubricating oil composition comprising a major amount of lubricating oil and a minor but effective amount of the gear oil additive package of  claim 8  to improve the load carrying and frictional properties of the lubricating composition 
     
     
         11 . A lubricating oil composition wherein the composition contains a major amount of an oil of lubricating viscosity and from about 1.0 to about 10.0 wt. % of said gear oil additive package of  claims 7  or  8   
     
     
         12 . The gear oil additive package of  claims 7  or  8 , wherein said borate is a potassium or sodium triborate. 
     
     
         13 . The gear oil additive package of  claims 7  or  8 , wherein said dihydrocarbyl dithiophosphate is an amine dithiophosphate salt. 
     
     
         14 . The lubricating oil composition of  claim 1  wherein the major amount of an oil of lubricating viscosity is selected from the group comprising Group I, Group II, Group III, Group IV or Fischer-Tropsch base oils. 
     
     
         15 . The lubricating oil composition of  claim 1  comprising a polyalkene co-oligomer. 
     
     
         16 . The lubricating oil composition of  claim 15  comprising from about 1-20 wt % of the polyalkene co-oligomer. 
     
     
         17 . A method of making a lubricating oil compositions comprising mixing a major amount of an oil of lubricating viscosity with
 (a) at least one hydrated alkali metal borate component;   (b) at least one dihydrocarbyl polysulfide component comprising a mixture including less than about 64.5 wt. % dihydrocarbyl trisulfide, greater than about 5.5 wt. % dihydrocarbyl disulfide, and at least about 30.0 wt. % dihydrocarbyl tetrasulfide or higher polysulfides;   (c) at least one non-acidic phosphorus component comprising a trihydrocarbyl phosphite component, at least 90 wt. % of which has the formula (RO) 3 P, wherein R is a hydrocarbyl group having 4 to 24 carbon atoms; and   (d) at least one dihydrocarbyl dithiophosphate.   
     
     
         18 . A method of making a gear additive package comprising mixing
 (a) at least one hydrated alkali metal borate component;   (b) at least one dihydrocarbyl polysulfide component comprising a mixture including less than about 64.5 wt. % dihydrocarbyl trisulfide, greater than about 5.5 wt. % dihydrocarbyl disulfide, and at least about 30.0 wt. % dihydrocarbyl tetrasulfide or higher polysulfides;   (c) at least one non-acidic phosphorous component comprising a trihydrocarbyl phosphite component, at least 90 wt % of which has the formula (RO) 3 P, wherein R is a hydrocarbyl group having 4 to 24 carbon atoms; and   (d) at least one dihydrocarbyl dithiophosphate.