Low viscosity functional fluids

Abstract

Low viscosity functional fluids are described which comprise glycols and an additive package that includes a fatty acid and a phosphate ester, such as a phosphate ester of an alkyl, alkenyl, or aryl alcohol. The fluids are particularly well-suit for use as DOT 3 or DOT 4 brake fluids and provide robust lubricity and corrosion inhibition.

1 . A fluid composition, comprising:
 at least one glycol; and   an additive package including at least one fatty acid and a phosphate ester   wherein the at least one glycol is present in an amount that is greater than about 20 percent by weight of the total fluid composition.   
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . A fluid composition in accordance with  claim 1 ,  3 , wherein the at least one glycol has the formula: 
       
         
           
           
               
               
           
         
         wherein R 1 , R 2 , R 3 , R 4 , and R 5  are independently selected from the group consisting of hydrogen and an alkyl group containing 1 to 8 carbon atoms, and n is at least 1. 
       
     
     
         5 . The fluid composition of  claim 4 , wherein the at least one glycol comprises a first glycol component in which n=2 and a second glycol component in which n=3. 
     
     
         6 . A fluid composition in accordance with  claim 4 , wherein the at least one glycol component comprises a first glycol component in which R 1  is an alkyl group containing 1 carbon atom and a second glycol component in which R 1  is an alkyl group containing 4 carbon atoms. 
     
     
         7 . A fluid composition in accordance with  claim 1 , further comprising at least one glycol borate ester present in an amount that is less than about 70 percent by weight of the fluid composition. 
     
     
         8 . (canceled) 
     
     
         9 . (canceled) 
     
     
         10 . A fluid composition in accordance with  claim 1 ,  9 , wherein the at least one fatty acid is linear. 
     
     
         11 . A fluid composition in accordance with  claim 1 , wherein the at least one fatty acid is monounsaturated. 
     
     
         12 . (canceled) 
     
     
         13 . (canceled) 
     
     
         14 . A fluid composition in accordance with  claim 1 , wherein the phosphate ester is a phosphate ester of an alcohol having a formula R 1 —R 2 —OH, wherein
 R 1  is selected from the group consisting of a substituted or unsubstituted alkyl, alkenyl, and aryl group, and 
 R 2  is selected from the group consisting of an alkyl group and an alkoxy group. 
 
     
     
         15 . The fluid composition of  claim 14 , wherein R 1  has at least 2 carbon atoms. 
     
     
         16 . (canceled) 
     
     
         17 . A fluid composition in accordance with  claim 14 , wherein R 1  is an alkyl-substituted aryl group. 
     
     
         18 . A fluid composition in accordance with  claim 14 , wherein R 2  is an ethoxy group. 
     
     
         19 . A fluid composition in accordance with  claim 14 , wherein R 1  is an unsubstituted alkenyl group. 
     
     
         20 . (canceled) 
     
     
         21 . (canceled) 
     
     
         22 . A fluid composition in accordance with  claim 1 , further comprising a polyalkylene glycol having the formula:
   R 7 —(O—(PO) m (EO) n —R 8 ) x  
   wherein   PO is a propylene oxide unit;   EO is an ethylene oxide unit;   R 7  is a hydrogen or an x-valent hydrocarbyl group;   x is at least 1;   R 8  is a hydrogen or a hydrocarbyl group;   m is a number of at least 0;   n is a number at of least 0; and   m+n is greater than 0.   
     
     
         23 . (canceled) 
     
     
         24 . (canceled) 
     
     
         25 . (canceled) 
     
     
         26 . (canceled) 
     
     
         27 . (canceled) 
     
     
         28 . (canceled) 
     
     
         29 . (canceled) 
     
     
         30 . (canceled) 
     
     
         31 . A fluid composition comprising at least one glycol and an additive package, wherein when the fluid composition is applied between a first surface comprising a composite of al polyamide 66 and b) 43 percent by weight glass fiber and a second surface comprising an EPDM rubber having a shore A hardness of 80, and the first surface slidably engages the second surface, the coefficient of friction is less than about 0.07 after 100 seconds of sliding engagement between the first and second surfaces. 
     
     
         32 . The fluid composition of  claim 31 , wherein the coefficient of friction is less than about 0.03 after 100 seconds of sliding engagement between the first and second surfaces. 
     
     
         33 . (canceled) 
     
     
         34 . (canceled) 
     
     
         35 . (canceled) 
     
     
         36 . A fluid composition in accordance with  claim 31 , wherein the at least one glycol has the formula: 
       
         
           
           
               
               
           
         
         wherein 
         R 1 , R 2 , R 3 , R 4 , and R 5  are independently selected from the group consisting of hydrogen and an alkyl group containing 1 to 8 carbon atoms, and n is at least 1. 
       
     
     
         37 . The fluid composition of  claim 36 , wherein the at least one glycol comprises a first glycol component in which n=2 and a second glycol component in which n=3. 
     
     
         38 . A fluid composition in accordance with  claim 36 , wherein the at least one glycol component comprises a first glycol component in which R 1  is an alkyl group containing 1 carbon atom and a second glycol component in which R 1  is an alkyl group containing 4 carbon atoms. 
     
     
         39 . A fluid composition in accordance with  claim 31 , further comprising at least one glycol borate ester present in an amount that is not greater than about 70 percent by weight of the fluid composition. 
     
     
         40 . A fluid composition in accordance with  claim 31 , further comprising at least one polyalkylene glycol having the formula:
   R 7 —(O—(PO) m (EO) n —R 8 ) x  
   wherein PO is a propylene oxide unit;   EO is an ethylene oxide unit;   R 8  is hydrogen or a hydrocarbyl group;   x is at least 1;   R 7  is hydrogen or an x valent hydrocarbyl group;   m is a number of at least 0;   n is a number at of least 0; and   m+n is greater than 0.   
     
     
         41 . (canceled) 
     
     
         42 . (canceled) 
     
     
         43 . (canceled) 
     
     
         44 . (canceled) 
     
     
         45 . (canceled)