Lubricating composition having improved storage stability

Abstract

A lubricating oil composition having superior storage stability and load-carrying effect is disclosed. The composition comprises four components: ( 1 ) an alkali metal borate; ( 2 ) an oil-soluble sulfur compound; ( 3 ) a trialkyl hydrogen phosphite; and ( 4 ) a mixture of greater than 50% neutralized acidic phosphates that are essentially free of monothiophosphates.

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) an oil-soluble sulfur-containing compound component;   (c) a trialkyl phosphite component, at least 90 wt. % of which has the formula (RO)3P, where R is alkyl of 4 to 24 carbon atoms; and   (d) a mixture of neutralized phosphates component, said phosphates being essentially free of monothiophosphates, 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 wt. % alkali metal borate; 
 (b) 0.1 to 10.0 wt. % sulfur-containing compound component; 
 (c) 0.01 to 10.0 wt. % trialkyl phosphite component; and 
 (d) 0.03 to 3.0 wt. % a mixture of neutralized phosphates component said phosphates being essentially free of monothiophosphates. 
 
     
     
         3 . The lubricant composition of  claim 2  where said borate is a potassium triborate. 
     
     
         4 . The lubricant composition of  claim 2  wherein said sulfur-containing compound is a sulfurized isobutylene. 
     
     
         5 . The lubricant composition of  claim 2  wherein said phosphite is a mixture of C10 to C20 trialkyl phosphites. 
     
     
         6 . The lubricant composition of  claim 2  wherein said phosphates comprise:
 (a) dihydrocarbyl hydrogen dithiophosphates; and 
 (b) a sulfur-free mixture of hydrocarbyl dihydrogen phosphates and dihydrocarbyl hydrogen phosphates, said composition being at least 50% neutralized by a hydrocarbyl amine having 10 to 30 carbon atoms in said hydrocarbyl group. 
 
     
     
         7 . The composition of  claim 6  wherein the hydrocarbyl groups in said dihydrocarbyl hydrogen dithiophosphate, hydrocarbyl dihydrogen phosphates, and dihydrocarbyl hydrogen phosphates are alkyl groups of 1 to 10 carbon atoms. 
     
     
         8 . A lubricating oil concentrate having enhanced storage stability, said concentrate comprising a mixture of:
 (a) a hydrated alkali metal borate component;   (b) an oil-soluble sulfur-containing compound component;   (c) a trialkyl phosphite component, at least 90 wt. % of which has the formula (RO)3P, where R is alkyl of 4 to 24 carbon atoms; and   (d) a mixture of neutralized phosphates component, said phosphates being essentially free of monothiophosphates, wherein the components of said mixture react synergistically to enhance 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) an oil-soluble sulfur-containing compound component;   (c) 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   (d) a mixture of neutralized phosphates component, said phosphates being essentially free of monothiophosphates, is blended with a major amount of a lubricating base oil, the components of said mixture reacting synergistically to enhance load carrying properties.   
     
     
         10 . The 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 triborate. 
     
     
         12 . The lubricant process of  claim 9  wherein said sulfur-containing compound is a sulfurized isobutylene. 
     
     
         13 . The lubricant process of  claim 9  wherein said phosphite is a mixture of C10 to C20 trialkyl phosphites. 
     
     
         14 . The lubricant process of  claim 9  wherein said phosphates comprise:
 (a) dihydrocarbyl hydrogen dithiophosphates; and 
 (b) a sulfur-free mixture of hydrocarbyl dihydrogen phosphates and dihydrocarbyl hydrogen phosphates, said composition being at least 
 
       50% neutralized by a hydrocarbyl amine having 10 to 30 carbon atoms in said hydrocarbyl group. 
     
     
         15 . A lubricating composition with enhanced storage stability comprising:
 (a) a major amount of a base oil of lubricating viscosity: and   (b) a minor amount of an additive concentrate comprising:
 (i) alkali metal triborate dispersion 
 (ii) alkyl polysulfide 
 (iii) neutral phosphate, 
 (iv) trialkyl phosphite. 
   
     
     
         16 . A lubricating composition according to  claim 15  wherein the additive concentrate comprises from about 20 to 60 wt % of the alkali metal triborate dispersion, from about 10 to 50 wt % of the alkyl polysulfide, from about 1 to 12 wt % of the neutral phosphate, and from about 1 to 12 wt % of the trialkyl phosphite.