Hydraulic fluids

Abstract

Invention relates to an aqueous hydraulic fluid comprising, in addition to water, at least one phospholipid lubricant, wherein the hydraulic fluid comprises less than 20% by weight of an oil selected from a mineral oil, a synthetic hydrocarbon oil or any mixture thereof. Preferably the or each phospholipid lubricant comprises a plant-derived lecithin.

1 . An aqueous hydraulic fluid comprising, in addition to water, at least one phospholipid lubricant, wherein the hydraulic fluid comprises less than 20% by weight of an oil selected from a mineral oil, a synthetic hydrocarbon oil or any mixture thereof.  
   
   
       2 . An aqueous hydraulic fluid as claimed in  claim 1  comprising water in an amount at least substantially 10% wt of the total weight of the hydraulic fluid.  
   
   
       3 . An aqueous hydraulic fluid as claimed in  claim 1  comprising water in an amount of no more than substantially 95% wt of the total weight of the hydraulic fluid.  
   
   
       4 . An aqueous hydraulic fluid as claimed in  claim 1  wherein the phospholipid lubricant comprises a phosphatide, especially having a structure  
     
       
         
         
             
             
         
       
       wherein at least one R is a phosphorus containing group having the structure  
       
         
           
           
               
               
           
         
       
       and at least one R is a fatty acyl group; and 
 wherein R′ is independently an alkyl group independently having from 1 to 12 carbon atoms and R″ is an alkyl group independently having from 1 to 8 carbon atoms.  
 
     
   
   
       5 . An aqueous hydraulic fluid as claimed in  claim 4  wherein one R group is a phosphorus containing group and two R groups are fatty acyl groups.  
   
   
       6 . An aqueous hydraulic fluid as claimed in  claim 4  comprising at least one phosphatide selected from phosphatidylcholine, phosphatidylinositol, phosphatidylserine and phosphatidylethanolamine.  
   
   
       7 . An aqueous hydraulic fluid as claimed in  claim 1  comprising more than one phospholipid.  
   
   
       8 . An aqueous hydraulic fluid as claimed in  claim 7  wherein the hydraulic fluid comprises phosphatidylcholine, phosphatidylinositol and phosphatidylethanolamine.  
   
   
       9 . An aqueous hydraulic fluid as claimed in  claim 1  wherein the total concentration of one or all of the phosphalipid lubricants comprises at least substantially 0.1% wt of the total weight of the hydraulic fluid.  
   
   
       10 . An aqueous hydraulic fluid as claimed in  claim 1  wherein the total concentration of one or all of the phospholipid lubricants comprises no more than substantially 30% wt of the total weight of the hydraulic fluid.  
   
   
       11 . An aqueous hydraulic fluid as claimed in  claim 1  comprising a plant-derived lecithin comprising a mixture of phosphatides and/or phospholipids.  
   
   
       12 . An aqueous hydraulic fluid as claimed in  claim 11  wherein the plant-derived lecithin is selected from soybean lecithin, castor lecithin, rapeseed lecithin, cottonseed lecithin and mixtures thereof.  
   
   
       13 . An aqueous hydraulic fluid as claimed in  claim 11  wherein the plant-derived lecithin is soybean lecithin.  
   
   
       14 . An aqueous hydraulic fluid as claimed in  claim 11  wherein the plant-derived lecithin comprises at least 1% wt of the total weight of hydraulic fluid.  
   
   
       15 . An aqueous hydraulic fluid as claimed in  claim 1  wherein one of or each phospholipid, or mixture of phospholipids is substantially the sole lubricant in the hydraulic fluid.  
   
   
       16 . An aqueous hydraulic fluid as claimed in  claim 1  further comprising at least one corrosion inhibitor.  
   
   
       17 . An aqueous hydraulic fluid as claimed in  claim 16  wherein the corrosion inhibitor comprises an alkylamine or alkanolamine.  
   
   
       18 . An aqueous hydraulic fluid as claimed in  claim 1  further comprising an anti-freeze additive.  
   
   
       19 . An aqueous hydraulic fluid as claimed in  claim 18  wherein the anti-freeze additive is selected from a glycol compound, glycerol, or a glycerol ester.  
   
   
       20 . An aqueous hydraulic fluid as claimed in  claim 1  comprising less than 10% wt of a mineral oil, synthetic hydrocarbon oil or mixture thereof.  
   
   
       21 . An aqueous hydraulic fluid as claimed in  claim 1  comprising less than 1% wt of a mineral oil, synthetic hydrocarbon oil or mixture thereof.  
   
   
       22 . An aqueous hydraulic fluid as claimed in  claim 1  comprising less than 0.1% wt of a mineral oil, synthetic hydrocarbon oil or mixture thereof.  
   
   
       23 . An aqueous hydraulic fluid as claimed in  claim 1  which is substantially free of mineral oil, synthetic hydrocarbon oil and mixtures thereof.  
   
   
       24 . An aqueous hydraulic fluid as claimed in  claim 1  substantially free of phosphorodithioates.  
   
   
       25 . (canceled)  
   
   
       26 . A stable aqueous hydraulic fluid comprising, in addition to water, a plant-derived lecithin as substantially the sole lubricant of the hydraulic fluid, and at least one component selected from a glycol, a glycerol ester, and glycerol, wherein the hydraulic fluid is substantially free of a mineral oil, a synthetic hydrocarbon oil or any mixture thereof, the water is present in an amount of at least 10% wt and no more than 90% wt of the total weight of the hydraulic fluid, and wherein the lecithin is present in an amount of from 0.1% wt up to substantially 40% wt of the total weight of the hydraulic fluid.  
   
   
       27 . Use of the aqueous hydraulic fluid of  claim 1  or  25  in an off-shore, mineral or mining drilling apparatus.  
   
   
       28 . The aqueous hydraulic fluid as claimed in  claim 4  wherein R″ is an alkyl group having from 1 to 4 carbon atoms.