Synthetic lubricant base stock formed from high content branched chain acid mixtures

Abstract

An improved synthetic ester lubricant base stock formed by reacting a neopentyl glycol with a mixture of aliphatic monocarboxylic acids is provided. The mixture of acids includes straight-chain acids having from 5 to 10 carbon atoms and an iso-acid having from 7 to 10 carbon atoms, preferably iso-nonanoic acid, wherein the iso-acid is present in about 60-90 weight percent of the acid charge. The base stock is mixed with a conventional ester lubricant additive package to form a lubricant having a viscosity at 210° F. of at least 7.0 with the resulting lubricants having a decreased tendency to form deposits in high temperature chain oil applications.

What is claimed is:  
     
         1 . A synthetic ester lubricant base stock, comprising the reaction product of: 
 a neopentyl polyol; and    an acid mixture including (1) at least one straight-chain acid having between about 5 and 10 carbon atoms and (2) an iso-acid selected from the group consisting of iso-C 7  acid, iso-C 8  acid, iso-C 9  acid, iso-C 10  acid and mixtures thereof;    the iso-acid present in an amount of from about 60 to 90 percent by weight of the acid mixture; and    the resulting mixture of ester when admixed with a synthetic ester lubricant additive package has a viscosity at 210° F. of at least about 7.0 centistokes.    
     
     
         2 . The synthetic ester lubricant base stock of  claim 1 , wherein the iso-acid is iso-nonanoic acid.  
     
     
         3 . The synthetic ester lubricant base stock of  claim 1 , wherein the iso-C 9  acid is 3,5,5-trimethylhexanoic acid.  
     
     
         4 . The synthetic ester lubricant base stock of  claim 1 , wherein the neopentyl polyol is selected from the group consisting of monopentaerythritol, dipentaerythritol, mixtures of trimethylolpropane and/or neopentyl glycol with a higher viscosity neopentyl polyol and mixtures thereof.  
     
     
         5 . The synthetic ester lubricant base stock of  claim 1 , wherein the polyol is a mixture of monopentaerythritol and dipentaerythritol.  
     
     
         6 . The synthetic ester lubricant base stock of  claim 1 , wherein the polyol is technical grade pentaerythritol.  
     
     
         7 . The synthetic ester lubricant base stock of  claim 2 , wherein the straight chain acid is a mixture of heptanoic acid (C 7  and caprylic-capric acid (C 8 -C 10 ).  
     
     
         8 . The synthetic ester lubricant base stock of  claim 7 , wherein the C 7  and C 8 -C 10  straight-chain acids are present in about equal amounts by weight.  
     
     
         9 . The synthetic ester lubricant base stock of  claim 8 , wherein the iso-nonanoic acid is present from about 65 to 75% by weight of the acid mixture.  
     
     
         10 . The synthetic ester lubricant base stock of  claim 2 , wherein the normal acid is valeric acid.  
     
     
         11 . The synthetic ester lubricant base stock of  claim 1 , admixed with an effective amont of a synthetic ester lubricant additive package for improving the high temperature properties and the load factor of the lubricant.  
     
     
         12 . A synthetic ester lubricant base stock consisting essentially of the reaction product of: 
 a polyol selected from the group consisting of monopentaerythritol, dipentaerythritol and mixtures thereof; and    a mixture of monocarboxylic acids including (1) straight-chain acids having from 5 to 10 carbon atoms and (2) iso-nonanoic acid;    the iso-nonanoic acid is present from about 60 to 90% by weight of the acid mixture; and    the resulting ester when admixed with a synthetic ester lubricant additive package has a viscosity at 210° F. of at least about 7.0 centistokes.    
     
     
         13 . The synthetic ester lubricant base stock of  claim 12 , wherein the iso-nonanoic acid is 3,5,5-trimethylhexanoic acid.  
     
     
         14 . The synthetic ester lubricant base stock of  claim 12 , wherein the straight chain acids are heptanoic acid and capric-caprylic acid.  
     
     
         15 . The synthetic ester lubricant base stock of  claim 12 , wherein the mixture of straight chain acids of heptanoic acid and caprylic-capric acid include about equal weights of each.  
     
     
         16 . The synthetic ester lubricant base stock of  claim 12 , admixed with an effective amount of a synthetic ester lubricant additive package for improving the high temperature properties and load factor of the lubricant.