Additive composition for transmission oil containing hydrated alkali metal borate and hexagonal boron nitride

Abstract

Disclosed are additive compositions for transmission oils comprising an oil dispersion of a hydrated alkali metal borate and an oil dispersion of hexagonal boron nitride, as well as lubricating oil compositions containing the same.

What is claimed is:  
     
         1 . An additive composition for a transmission oil comprising: 
 (a) an oil dispersion of a hydrated alkali metal borate; and    (b) an oil dispersion of hexagon boron nitride; wherein the weight ratio of the hydrated alkali metal borate to the hexagonal boron nitride is in the range of about 95:5 to about 5:95.    
     
     
         2 . The additive composition according to  claim 1 , wherein the alkali metal in the hydrated alkali metal borate is sodium or potassium.  
     
     
         3 . The additive composition according to  claim 2 , wherein the alkali metal is potassium.  
     
     
         4 . The additive composition according to  claim 3 , wherein the hydrated alkali metal borate is hydrated potassium triborate.  
     
     
         5 . The additive composition according to  claim 1 , wherein the oil dispersion of hydrated alkali metal borate contains a hydrated alkali metal borate, a dispersant and an oil of lubricating viscosity.  
     
     
         6 . The additive composition according to  claim 5 , wherein the oil dispersion of hydrated alkali metal borate contains about 10 to about 75 weight percent of the hydrated alkali metal borate, based on the total weight of the oil dispersion.  
     
     
         7 . The additive composition according to  claim 5 , wherein the oil dispersion of hydrated alkali metal borate contains about 2 to about 40 weight percent of the dispersant, based on the total weight of the oil dispersion.  
     
     
         8 . The additive composition according to  claim 5 , wherein the oil dispersion of hydrated alkali metal borate further contains a detergent.  
     
     
         9 . The additive composition according to  claim 8 , wherein the oil dispersion of hydrated alkali metal borate contains about 0.2 to about 10 weight percent of the detergent, based on the total weight of the oil dispersion.  
     
     
         10 . The additive composition according to  claim 1 , wherein the oil dispersion of hydrated alkali metal borate is present in the additive composition in the range of about 10 to about 90 weight percent, based on the total weight of the additive composition.  
     
     
         11 . The additive composition according to  claim 1 , wherein the hexagonal boron nitride has a particle size distribution wherein 90% or greater of the particles are less than about 0.5 microns.  
     
     
         12 . The additive composition according to  claim 1 , wherein the oil dispersion of hexagonal boron nitride contains an oil of lubricating viscosity and about 1 to about 50 weight percent of hexagonal boron nitride, based on the total weight of the oil dispersion.  
     
     
         13 . The additive composition according to  claim 12 , wherein the oil dispersion of hexagonal boron nitride further contains a surfactant as a stabilizer.  
     
     
         14 . The additive composition according to  claim 1 , wherein the oil dispersion of hexagonal boron nitride is present in the additive composition in the range of about 10 to about 90 weight percent, based on the total weight of the additive composition.  
     
     
         15 . A lubricating oil composition comprising a major amount of a transmission oil of lubricating viscosity and an effective synchronizer sticking reducing amount of an additive composition comprising: 
 (a) an oil dispersion on a hydrated alkali metal borate; and    (b) an oil dispersion of hexagonal boron nitride;    wherein the weight ratio of the hydrated alkali metal borate to the hexagonal boron nitride is in the range of about 95:5 to about 5:95.    
     
     
         16 . The lubricating oil composition according to  claim 15 , wherein the lubricating oil composition contains about 1 to about 20 weight percent of the additive composition, based on the total weight of the lubricating oil composition.  
     
     
         17 . The lubricating oil composition according to  claim 15 , wherein the transmission oil is a manual transmission gear oil.