High viscosity synthetic ester lubricant base stock

Abstract

A high viscosity synthetic ester base stock of about ISO 68 to 400 is formed from a neopentylpolyol condensed with at least one monocarboxylic acid selected from the group consisting of linear acids having between 4 to 10 carbon atoms and branched chain acids having from 5 to 10 carbon atoms in an excess of hydroxyl to carboxylic acid groups to form a partial polyneopentylpolyol ester that is further reacted with the same or similar acid to form a high viscosity polyneopentylpolyol ester. Lubricants formed from the base stocks have satisfactory miscibility with standard highly or fully fluorinated refrigeration fluids.

1 . A high viscosity synthetic polyneopentylpolyol ester lubricant base stock, comprising the reaction mixture formed by 
 reacting a neopentylpolyol having less than 10 carbon atoms with at least one monocarboxylic acid selected from the group consisting of linear monocarboxylic acids having from 4 to 10 carbon atoms and branched chain acids having from 5 to 10 carbon atoms, in the presence of an excess of hydroxyl groups, and an acid catalyst to form polyneopentylpolyol partial esters,    neutralizing the acid catalyst; and    reacting the partial polyneopentylpolyol esters with at least one monocarboxylic acid selected from the group consisting of linear acids having from 4 to 10 carbon atoms, and branched chain acids having from 5 to 10 carbon atoms,    the resulting polyneopentylpolyol ester having a viscosity from about 68 to 400 cSt at 40° C.    
     
     
         2 . The base stock of  claim 1 , wherein the polyneopentylpolyol partial ester is formed in the presence of an excess of hydroxyl groups in a mole ratio of carboxyl groups to hydroxyl groups in the reaction mixture in a range from about 0.25:1 to about 0.50:1; and the partial polyneopentylpolyol esters are reacted with an excess of about 15 weight percent of acid to yield with the final ester base stock.  
     
     
         3 . The base stock of  claim 1 , wherein the polyneopentylpolyol ester is formed from a polyneopentylpolyol partial ester which is formed from a neopentylpolyol represented by the following structural formula:  
       
         
           
           
               
               
           
         
       
       wherein each R is selected from the group consisting of —CH 3 , —C 2 H 5 , and —CH 2 OH.  
     
     
         4 . The base stock of  claim 3 , wherein the neopentylpolyol is a polyol selected from the group consisting of pentaerythritol, trimethylolpropane, trimethylolethane, neopentyl glycol, and mixtures thereof.  
     
     
         5 . The base stock of  claim 3 , wherein the neopentylpolyol is pentaerythritol.  
     
     
         6 . The base stock of  claim 1 , wherein the linear acid reacted with the neopentylpolyol is valeric acid.  
     
     
         7 . The base stock of  claim 1 , wherein the branched chain acid reacted with the neopentylpolyol is a nine carbon atom acid.  
     
     
         8 . The base stock of  claim 7 , wherein the branched chain acid is 3,5,5-trimethylhexanoic acid.  
     
     
         9 . The base stock of  claim 1 , wherein the linear acid reacted with the polyneopentylpolyol partial ester is valeric acid.  
     
     
         10 . The base stock of  claim 1 , wherein the branched chain acid reacted with the polyneopentylpolyol partial ester is a nine carbon atom acid.  
     
     
         11 . The base stock of  claim 10 , wherein the branched chain acid is 3,5,5-trimethylhexanoic acid.  
     
     
         12 . A method of preparation of high viscosity synthetic polyneopentylpolyol ester lubricant base stocks, comprising: 
 reacting a neopentylpolyol having less than 10 carbon atoms with at least one monocarboxylic acid selected from the group consisting of linear monocarboxylic acids having from 4 to 10 carbon atoms and branched chain acids having from 5 to 10 carbon atoms, in the presence of an excess of hydroxyl groups, and an acid catalyst to form partial polyneopentylpolyol esters,    neutralizing the acid catalyst; and    reacting the partial polyneopentylpolyol esters with at least one monocarboxylic acid selected from the group consisting of linear acids having from 4 to 10 carbon atoms, and branched chain acids having from 5 to 10 carbon atoms, and    the resulting polyneopentylpolyol ester having a viscosity from about 68 to 400 cSt at 40° C.    
     
     
         13 . A method of preparation of high viscosity synthetic polyneopentylpolyol ester lubricant base stocks, comprising 
 reacting a neopentylpolyol having less than 10 carbon atoms with a monocarboxylic acid mixture of (i) at least one linear monocarboxylic acid having from 4 to 10 carbon atoms, and (ii) at least one branched chain monocarboxylic acid having from 5 to 10 carbon atoms, in the presence of an excess of hydroxyl groups and an acid catalyst to form polyneopentylpolyol partial esters,    neutralizing the acid catalyst; and    reacting the partial polyneopentylpolyol partial esters with a monocarboxylic acid mixture of (i) at least one linear monocarboxylic acid having from 4 to 7 carbon atoms, and (ii) at least one branched chain monocarboxylic acid having from 6 to 10 carbon atoms,    the resulting polyneopentylpolyol ester having a viscosity from about 68 to 400 cSt at 40° C.    
     
     
         14 . A refrigeration compressor fluid comprising, a highly or fully fluorinated refrigerant and between about 5 to 20 weight percent of a high viscosity synthetic polyneopentylpolyol ester lubricant including a polyneopentylpolyol ester reaction mixture formed by 
 reacting a neopentylpolyol having less than 10 carbon atoms with at least one monocarboxylic acid selected from the group consisting of linear monocarboxylic acids having from 4 to 10 carbon atoms and branched chain acids having from 5 to 10 carbon atoms, in the presence of an excess of hydroxyl groups, and an acid catalyst to form partial polyneopentylpolyol esters,    neutralizing the acid catalyst; and    reacting the partial polyneopentylpolyol esters with at least one monocarboxylic acid selected from the group consisting of linear acids having from 4 to 10 carbon atoms, and branched chain acids having from 5 to 10 carbon atoms,    the resulting polyneopentylpolyol ester having a viscosity from about 68 to 400 cSt at 40° C.    
     
     
         15 . A high viscosity synthetic polyneopentylpolyol ester lubricant base stock, comprising the reaction mixture formed by 
 reacting a neopentylpolyol having less than 10 carbon atoms with (1) at least one linear monocarboxylic acid having from 4 to 10 carbon atoms and (2) at least one branched chain monocarboxylic acids acid having from 5 to 10 carbon atoms, in the presence of an excess of hydroxyl groups, and an acid catalyst to form polyneopentylpolyol partial esters,    neutralizing the acid catalyst; and    reacting the polyneopentylpolyol partial esters with at least one monocarboxylic acid selected from the group consisting of linear acids having from 4 to 10 carbon atoms, and branched chain acids having from 5 to 10 carbon atoms,    the resulting polyneopentylpolyol ester having a viscosity from about 68 to 400 cSt at 40° C.    
     
     
         16 . The base stock of  claim 1 , wherein the acid reacted with the neopentylpolyol is a mixture of a linear acid a branched chain acid in a mole ratio between about 5:1 to 1:5.  
     
     
         17 . The base stock of  claim 16 , wherein the mole ratio is between about 1:1 to 1:4.  
     
     
         18 . The base stock of  claim 16 , wherein the mole ratio is between about 1:3 to 1:4.  
     
     
         19 . The base stock of  claim 17 , wherein the linear acid is valeric acid and the branched acid is 3,5,5-trimethylhexanoic acid.  
     
     
         20 . The base stock of  claim 18 , wherein the linear acid is valeric acid and the branched acid is 3,5,5-trimethylhexanoic acid.