Antiwear hydraulic fluid composition with useful emulsifying and rust prevention properties

Abstract

Disclosed are antiwear hydraulic fluid compositions comprising (a) a major amount of a base oil of lubricating viscosity and (b) a minor amount of at least one oil soluble detergent additive comprising a salt of an alkyl-substituted hydroxybenzoic acid or a sulfurized derivative thereof, wherein said salt is selected from the group consisting of alkali metal salts, alkaline earth metal salts, ammonium salts or substituted ammonium salts, and further wherein said antiwear hydraulic fluid compositions have a Carboxylate Index of greater than levels disclosed herein.

1 . An antiwear hydraulic fluid composition comprising (a) a major amount of a base oil of lubricating viscosity and (b) a minor amount of at least one oil soluble detergent additive comprising a salt of an alkyl-substituted hydroxybenzoic acid or a sulfurized derivative thereof, wherein said salt is selected from the group consisting of alkali metal salts, alkaline earth metal salts, ammonium salts or substituted ammonium salts, and further wherein said antiwear hydraulic fluid composition has a Carboxylate Index of greater than 0.084. 
   
   
       2 . The antiwear hydraulic fluid composition according to  claim 1 , wherein said alkyl-substituted hydroxybenzoic acid comprises a linear or branched alkyl group or a mixture of linear and branched alkyl groups. 
   
   
       3 . The antiwear hydraulic fluid composition according to  claim 1  wherein at least 90% of the alkyl groups of said alkyl-substituted hydroxybenzoic acid are C 14  or greater. 
   
   
       4 . The antiwear hydraulic fluid composition according to  claim 1  wherein said antiwear hydraulic fluid composition is able to achieve an emulsion of 0-0-80 at 40 minutes in the ASTM D 1401 water separability test method. 
   
   
       5 . The antiwear hydraulic fluid composition according to  claim 1 , wherein said salt comprises a calcium salt. 
   
   
       6 . The antiwear hydraulic fluid composition according to  claim 1 , wherein said hydraulic fluid composition comprises no added rust inhibitors. 
   
   
       7 . The antiwear hydraulic fluid composition according to  claim 1 , wherein said oil soluble detergent additive comprises a TBN of less than 200 mg KOH/g. 
   
   
       8 . The antiwear hydraulic fluid composition according to  claim 1 , wherein said oil soluble detergent additive comprises a TBN of less than 160 mg KOH/g. 
   
   
       9 . The antiwear hydraulic fluid composition according to  claim 1 , wherein said oil soluble detergent additive comprises greater than 0.1 weight percent of the total weight of said antiwear hydraulic fluid composition. 
   
   
       10 . The antiwear hydraulic fluid composition according to  claim 1 , wherein said oil soluble detergent additive comprises greater than 0.2 weight percent of the total weight of said antiwear hydraulic fluid composition. 
   
   
       11 . The antiwear hydraulic fluid composition of  claim 1  further comprising at least one of these co-additives: (a) an ashless dispersant; (b) an oxidation inhibitor; (d) a demulsifier; (e) an extreme pressure agent; (f) a friction modifier; (g) a multifunctional additive; (h) a viscosity index improver; (i) a pour point depressant; () a foam inhibitor; and (k) an emulsifier. 
   
   
       12 . An antiwear hydraulic fluid composition comprising (a) a major amount of a base oil of lubricating viscosity and (b) a minor amount of at least one oil soluble detergent additive comprising a salt of an alkyl-substituted hydroxybenzoic acid or a sulfurized derivative thereof, wherein said salt is selected from the group consisting of alkali metal salts, alkaline earth metal salts, ammonium salts or substituted ammonium salts, and further wherein said antiwear hydraulic fluid composition has a Carboxylate Index of greater than 0.034. 
   
   
       13 . The antiwear hydraulic fluid composition according to  claim 12 , wherein said alkyl-substituted hydroxybenzoic acid comprises a linear or branched alkyl group or a mixture of linear and branched alkyl groups. 
   
   
       14 . The antiwear hydraulic fluid composition according to  claim 12  wherein at least 90% of the alkyl groups of said alkyl-substituted hydroxybenzoic acid are C 14  or greater. 
   
   
       15 . The antiwear hydraulic fluid composition according to  claim 12  wherein said antiwear hydraulic fluid composition is able to achieve a pass result in the ASTM D 665 rust inhibition method. 
   
   
       16 . The antiwear hydraulic fluid composition according to  claim 12 , wherein said salt comprises a calcium salt. 
   
   
       17 . The antiwear hydraulic fluid composition according to  claim 12 , wherein said hydraulic fluid composition comprises no added rust inhibitors. 
   
   
       18 . The antiwear hydraulic fluid composition according to  claim 12 , wherein said oil soluble detergent additive comprises a TBN of less than 200 mg KOH/g. 
   
   
       19 . The antiwear hydraulic fluid composition according to  claim 12 , wherein said oil soluble detergent additive comprises a TBN of less than 160 mg KOH/g. 
   
   
       20 . The antiwear hydraulic fluid composition according to  claim 12 , wherein said oil soluble detergent additive comprises greater than 0.05 weight percent of the total weight of said antiwear hydraulic fluid composition. 
   
   
       21 . The antiwear hydraulic fluid composition according to  claim 12 , wherein said oil soluble detergent additive comprises greater than 0.07 weight percent of the total weight of said antiwear hydraulic fluid composition. 
   
   
       22 . The antiwear hydraulic fluid composition of  claim 12  further comprising at least one of these co-additives: (a) an ashless dispersant; (b) an oxidation inhibitor; (d) a demulsifier; (e) an extreme pressure agent; (f) a friction modifier; (g) a multifunctional additive; (h) a viscosity index improver; (i) a pour point depressant; () a foam inhibitor; and (k) an emulsifier.