Hydraulic fluid compositions

Abstract

An aqueous hydraulic fluid composition comprising a first lubricant comprising at least one phospholipid and a second lubricant comprising an alkoxylate salt. The aqueous hydraulic fluid composition contains less than about 20% by weight (preferably none or substantially none) of an oil selected from the group consisting of mineral oils, synthetic hydrocarbon oils, and mixtures thereof. The use of alkoxylate salts provides increased lubricity and also acts as an emulsion stabilizer for the composition.

1 . An aqueous hydraulic fluid composition comprising:
 a first lubricant comprising at least one phospholipid; and   a second lubricant comprising an alkoxylate salt;   wherein the hydraulic fluid composition comprises is substantially free of an oil selected from the group consisting of mineral oils, synthetic hydrocarbon oils, and mixtures thereof.   
   
   
       2 . The aqueous hydraulic fluid composition according to  claim 1 , wherein the composition comprises water in an amount between about 10% and about 95% by weight based on the total weight of the hydraulic fluid composition. 
   
   
       3 . The aqueous hydraulic fluid composition according to  claim 1 , wherein the phospholipid lubricant comprises a phosphatide selected from the group consisting of phosphatidylcholine, phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine and combinations of one or more of the foregoing. 
   
   
       4 . The aqueous hydraulic fluid composition of  claim 1  wherein the alkoxylate salt comprises a calcium, magnesium or zinc salt of an alkoxylate selected from the group consisting of laurates, palmitates, oleates and stearates. 
   
   
       5 . The aqueous hydraulic fluid composition according to  claim 1 , wherein the alkoxylate salt is selected from the group consisting of calcium stearate, zinc stearate and magnesium stearate. 
   
   
       6 . The aqueous hydraulic fluid composition according to  claim 4 , wherein the alkoxylate salt is calcium stearate. 
   
   
       7 . The aqueous hydraulic fluid composition according to  claim 1 , wherein the composition further comprises a biocide. 
   
   
       8 . The aqueous hydraulic fluid composition according to  claim 7 , wherein the biocide is selected from the group consisting of a boron containing salt, triazines, oxazolidines, guanidines, and fatty acid quaternary ammonium salts. 
   
   
       9 . The aqueous hydraulic fluid composition according to  claim 8 , wherein the biocide is borax decahydrate. 
   
   
       10 . The aqueous hydraulic fluid composition according to  claim 1 , wherein the composition further comprises a corrosion inhibitor. 
   
   
       11 . The aqueous hydraulic fluid composition according to  claim 10 , wherein the corrosion inhibitor is selected from the group consisting of inorganic phosphates, alkylcarboxylic acids neutralized with an alkanolamine, alkylamines, alkanolamines, amine carboxylates, and benzotriazoles 
   
   
       12 . The aqueous hydraulic fluid composition according to  claim 1 , wherein the composition further comprises an anti-freeze additive. 
   
   
       13 . The aqueous hydraulic fluid composition according to  claim 12 , wherein the anti-freeze additive is selected from the group consisting of monoethylene glycol, glycerol, propylene glycol, 2-butene-1,4-diol, polyethylene glycols and polypropylene glycols. 
   
   
       14 . The aqueous hydraulic fluid composition according to  claim 13 , wherein the anti-freeze additive is monoethylene glycol.