Lubricating compositions

Abstract

A lubricating composition comprising: (i) from 50% to 99% by weight of base oil; (ii) from 0.01% to 5% by weight of ionic liquid; and (iii) from 0.01% to 10% by weight of additive; wherein the lubricating composition has a pour point of at most −54° C., a flashpoint of at least 246° C. and a kinematic viscosity at 100° C. in the range of from 4.9 to 5.4 mm 2 /s. The lubricating compositions according to the present invention are suitable for use in turbine engine oils and are useful for reducing the build up of sludge and for reducing coking in the lubricating composition.

1 . A lubricating composition comprising:
 (i) from 50% to 99% by weight of base oil;   (ii) from 0.01% to 5% by weight of ionic liquid; and   (iii) from 0.01% to 10% by weight of additive;   wherein the lubricating composition has a pour point of less than −54° C., a flashpoint of greater than 246° C. and a kinematic viscosity at 100° C. in the range of from 4.9 to 5.4 mm 2 /s.   
     
     
         2 . A lubricating composition according to  claim 1  comprising from 0.01% to 1% by weight of ionic liquid. 
     
     
         3 . The lubricating composition according to  claim 1  comprising from 0.05% to 0.5% by weight ionic liquid. 
     
     
         4 . A lubricating composition wherein the ionic liquid is a salt of general formula C + A −  wherein the cation C +  is selected from a quaternary ammonium cation, a phosphonium cation, an imidazolium cation, a pyridinium cation, a pyrazolium cation, an oxazolium cation, a pyrrolidinium cation, a piperidinium cation, a trialkylsulfonium cation, a thiazolium cation, a guanidinium cation, a morpholinium cation, a sulfonium cation and a triazolium cation and wherein the anion A − is selected from [PF 6 ] − , [CF 3 CO 2 ] − , [CF 3 SO 3 ] − , as well as its higher homologues, [C 4 F 9 SO 3 ] −  or [C 8 F 17 SO 3 ] −  and higher perfluoroalkylsulfonates, [(CF 3 SO 2 ) 2 N], [(CF 3 SO 2 )(CF 3 COO)N] − , Cl − , Br − , I − , [C(CN) 3 ] − , SCN − , [B(C 2 O 4 ) 2 ] − , [N(SO 2 CF 3 ) 2 ] − , [R 4 SO 3 ] − , [R 4 OSO 3 ] − , [R 4 COO] − , [NO 3 ] − , [N(CN) 2 ] − , [HSO 4 ] − , PF 6-x R 6   x  or [R 4 R 5 PO 4 ] − , wherein R 4  and R 5  are independently selected from hydrogen, linear or branched, saturated or unsaturated, aliphatic or alicyclic alkyl groups with 1 to 20 carbon atoms; heteroaryl, heteroaryl-C 1 -C 6 -alkyl groups with 3 to 8 carbon atoms in the hetero aryl residue and at least one heteroatom selected from N, O and S, which can be substituted with at least one group selected from C 1 -C 6  alkyl groups and/or halogen atoms; aryl-aryl-C 1 -C 6 -alkyl groups with 5 to 12 carbon atoms in the aryl residue, which can be substituted with at least one C 1 -C 6 -alkyl group, R 6  can be a perfluoroethyl or a higher perfluoroalkyl group, and x is an integer of from 1 to 4. 
     
     
         5 . The lubricating composition according to  claim 4  wherein the ionic liquid is selected from butyl methylpyrrolidinium-bis(trifluoromethylsulfonyl)imide, methylpropylpyrrolidinium-bis(trifluoromethylsulfonyl)imide, tris-hexylmethylimidazolium (perfluoroethylene)-trifluorophosphate, hexylmethylimidazolium-bis(trifluoromethylsulfonyl)imide, hexylmethylpyrrolidinium-bis(trifluoromethylsulfonyl)imide, tris-tetrabutylphosphonium(perfluoroethylene)trifluorophosphate, octylmethylimidazolium-hexafluorophosphate, hexylpyridinium-bis(trifluoromethyl)sulfonylimide, methyltrioctylammonium-trifluoroacetate, butylmethylpyrrolidinium tris (pentafluoroethyl)trifluorophosphate, trihexyl (tetradecyl)phosphonium-bis(trifluoromethylsulfonyl)imide, hexylmethylimidazolium tetrafluoroborate, hexylmethylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium diethylphosphate, 1-ethyl-3-methylimidazolium methyl sulphate, 1-ethyl-3-methylimidazolium bis[oxalate(2-)-O,O+]borate and mixtures thereof. 
     
     
         6 . The lubricating composition according to  claim 4  wherein the ionic liquid is selected from methyltrioctylammonium-trifluoroacetate and trihexyl (tetradecyl)phosphonium-bis(trifluoromethylsulfonyl)imide, hexylmethylimidazolium tetrafluoroborate, hexylmethylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium diethylphosphate, 1-ethyl-3-methylimidazolium methyl sulphate and mixtures thereof. 
     
     
         7 . The lubricating composition according to  claim 4  wherein the ionic liquid is selected from trihexyl(tetradecyl)phosphonium-bi(trifluoromethylsulfonyl)imide, hexylmethylimidazolium hexafluorophosphate, and mixtures thereof. 
     
     
         8 . The lubricating composition according to  claim 4  wherein the base oil is a synthetic ester formed by the reaction of a polyol with a carboxylic acid of formula RCOOH wherein R is a straight or branched chain hydrocarbyl group having from 5 to 10 carbon atoms. 
     
     
         9 . The use of a lubricating composition according to  claim 4  for lubricating a turbine engine. 
     
     
         10 . The use of an ionic liquid according to  claim 4  to reduce the sludge content of a lubricating composition comprising (i) a base oil, (ii) an ionic liquid and (iii) one or more additives. 
     
     
         11 . The use of an ionic liquid to according to  claim 4  reduce the coking of a lubricating composition comprising (i) a base oil, (ii) an ionic liquid and (iii) one or more additives.