Lubricating composition containing non-acidic phosphorus compounds

Abstract

A lubricating composition with improved storage stability comprising a major amount of an oil of lubricating viscosity, at least one alkali metal borate, at least one polysulfide mixture having at least 40% dihydrocarbyl tetrasulfide or higher sulfides, and at least one non-acidic phosphorus compound comprised of a trihydrocarbyl phosphate and a dihydrocarbyl dithiophosphate derivative is disclosed. In addition to improved storage stability, the composition has improved wear performance when the ratio of polysulfides is controlled.

1 . A lubricating composition having enhanced storage stability and load carrying properties, said composition comprising an oil of lubricating viscosity wherein a minor amount of a mixture of the following components is dispersed:
 (a) a hydrated alkali metal borate component;   (b) a dihydrocarbyl polysulfide component comprising a mixture including no more than 70 wt. % dihydrocarbyl trisulfide, more than 5.5 wt. % dihydrocarbyl disulfide, and at least 30 wt. % dihydrocarbyl tetrasulfide or higher polysulfides; and   (c) a non-acidic phosphorus component comprising a trihydrocarbyl phosphate component, at least 90 wt. % of which has the formula (RO) 3 P, where R is alkyl of 4 to 24 carbon atoms and at least one dihydrocarbyl dithiophosphate derivative wherein the components of said mixture react synergistically to enhance the load carrying properties and storage stability of the lubricant composition.   
     
     
         2 . The composition of  claim 1  wherein said lubricating composition comprises:
 (a) 0.1 to 20.0 wt. % alkali metal borate; 
 (b) 0.1 to 10.0 wt. % the dihydrocarbyl polysulfide component; and 
 (c) 0.01 to 15.0 wt. % of a non-acidic phosphorus component; 
 
     
     
         3 . The lubricant composition of  claim 1 , wherein said borate is a potassium or sodium triborate. 
     
     
         4 . The lubricant composition of  claim 1 , wherein said trialkyl phosphite is a mixture of C 10  to C 20  trialkyl phosphites. 
     
     
         5 . The lubricant composition of  claim 1 , wherein the dihydrocarbyl dithiophosphate is derived from an acidic phosphate which has been at least 80% neutralized. 
     
     
         6 . The lubricant composition of  claim 5 , wherein the dihydrocarbyl dithiophosphate is derived from an acidic phosphate which has been from 85% to 100% neutralized. 
     
     
         7 . The lubricant composition of  claim 5 , wherein the dihydrocarbyl dithiophosphate is an acid, ester, or salt derivative. 
     
     
         8 . A lubricating oil concentrate having enhanced storage stability and load-carrying properties, said concentrate comprising a mixture of:
 (a) a hydrated alkali metal borate component;   (b) a dihydrocarbyl polysulfide component comprising a mixture including no more than 70 wt. % dihydrocarbyl trisulfide, more than 5.5 wt. % dihydrocarbyl disulfide, and at least 30 wt. % dihydrocarbyl tetrasulfide or higher polysulfides; and   (c) a non-acidic phosphorus component comprising a trialkyl phosphate component, at least 90 wt. % of which has the formula (RO) 3P, where R is alkyl of 4 to 24 carbon atoms and at least one dihydrocarbyl dithiophosphate, wherein the components of said mixture react synergistically to enhance the load carrying properties and storage stability when blended with a lubricating base oil to create a lubricant composition.   
     
     
         9 . A process for the preparation of a lubricant composition having enhanced storage stability and load carrying properties, wherein a minor but effective amount of a lubricating oil concentrate comprising a mixture of:
 (a) a hydrated alkali metal borate component;   (b) a dihydrocarbyl polysulfide component comprising a mixture including no more than 70 wt. % dihydrocarbyl trisulfide, more than 5.5 wt. % dihydrocarbyl disulfide, and at least 30 wt. % dihydrocarbyl tetrasulfide or higher polysulfides; and   (c) a non-acidic phosphorus component comprising a trialkyl phosphate component, at least 90 wt. % of which has the formula (RO) 3P, where R is alkyl of 4 to 24 carbon atoms and at least one dihydrocarbyl dithiophosphate, is blended with a major amount of a lubricating base oil to form the composition, the components of said mixture reacting synergistically to enhance storage stability and load carrying properties.   
     
     
         10 . The lubricating process of  claim 9 , wherein the composition contains 1.0 to 10.0 wt. % of said concentrate. 
     
     
         11 . The lubricant process of  claim 9 , wherein said borate is a potassium or sodium triborate. 
     
     
         12 . The lubricant process of  claim 9 , wherein the dihydrocarbyl dithiophosphate is derived from an acidic phosphate which has been at least 80% neutralized. 
     
     
         13 . The lubricant process of  claim 12 , wherein the dihydrocarbyl dithiophosphate is derived from an acidic phosphate which has been from 85% to 100% neutralized. 
     
     
         14 . The lubricant process of  claim 9 , wherein the dihydrocarbyl dithiophosphate is an acid, ester, or salt derivative. 
     
     
         15 . A lubricating composition prepared by the process recited in  claim 9 .