Method for improving the coking resistance of a lubricating composition

Abstract

Disclosed is a method of lubrication including a step of lubricating a machine with a lubricating composition, the lubricating composition including 20-100% ionic liquid or of a mixture of several ionic liquids. The ionic liquid or the mixture is selected from at least: an anion A − chosen from sulfonylimides, the substituent(s) of which is (are) independently chosen from a fluoroalkyl, fluoroether, perfluorinated alkyl or perfluoroether group; and a cation C + including a nitrogen-containing heterocycle or a quaternary ammonium, the substituent(s) of which is (are) independently chosen from: a hydrogen atom or alkyl, alkoxy, fluorinated alkyl, perfluorinated alkyl, alkylsilane, alkyl alcohol, vinyl, alkyl allyl, ether or polyether groups having a linear or branched chain having 1-3 carbon atoms. The deposition start temperature in thin film of the ionic liquid or of the mixture of ionic liquids is at least equal to 330° C. The lubricating composition reduces deposits formed in the machine.

1 - 14 . (canceled) 
     
     
         15 . Method of lubrication which comprises a step of lubricating a machine with a lubricating composition, the lubricating composition comprising, in mass with respect to the total mass of said lubricating composition, from 20% to 100% of an ionic liquid or of a mixture of several ionic liquids,
 wherein said ionic liquid or said mixture of ionic liquids is selected from an ionic liquid or a mixture of ionic liquids comprising at least:   an anion A −  chosen from sulfonylimides, the substituent(s) of which is (are) independently chosen from a fluoroalkyl, fluoroether, perfluorinated alkyl or perfluoroether group, and   a cation C +  comprising a nitrogen-containing heterocycle or a quaternary ammonium, the substituent(s) of which is (are) independently chosen from: a hydrogen atom or alkyl, alkoxy, fluorinated alkyl, perfluorinated alkyl, alkylsilane, alkyl alcohol, vinyl, alkyl allyl, ether or polyether groups having a linear or branched chain having from 1 to 3 carbon atoms, on condition that when the cation is a quaternary ammonium, at least two of these substituents are a methyl group,   the deposition start temperature (TDD) in thin film, determined by the MCT method according to the standard GFC Lu-27 A-13, of the ionic liquid or of the mixture of ionic liquids being at least equal to 330° C.,   said lubricating composition being suitable to reduce the deposits formed in said machine.   
     
     
         16 . Method according to  claim 15 , in which the lubricating step is carried out at high temperatures of between 200 and 500° C. 
     
     
         17 . Method according to  claim 15 , in which said cation C +  comprising a nitrogen-containing heterocycle is selected among: imidazolium, pyrazolium, quinolium, pyridinium, piperidinium, oxazolium, thiazolium, benzothiazolium or morpholinium. 
     
     
         18 . Method according to  claim 15 , in which the cation C +  comprising a nitrogen-containing heterocycle is selected among: imidazolium, pyridinium, or pyrazolium. 
     
     
         19 . Method according to  claim 15 , in which the deposition start temperature (TDD) in thin film, determined by the method MCT according to the standard GFC Lu-27 A-13, of said ionic liquid or of said mixture of ionic liquids is at least equal to 350° C. 
     
     
         20 . Method according to  claim 17 , in which the cation C +  is imidazolium comprising at least two methyl groups at position 1 and 2 or at position 2 and 3, or a pyridinium comprising at least one methyl group. 
     
     
         21 . Method according to  claim 20 , in which the cation C +  is a pyridinium comprising at least one methyl group at position 3, 4 or 5. 
     
     
         22 . Method according to  claim 20 , in which the imidazolium comprising a methyl group at position 1 and 2 or at position 2 and 3 comprises a hydrogen atom at position 4 and 5. 
     
     
         23 . Method according to  claim 22 , in which the imidazolium cation C +  is 1-ethyl-2,3-dimethylimidazolium or 1,2-dimethyl-3-((trimethylsilyl)methyl)imidazolium. 
     
     
         24 . Method according to  claim 22 , in which the imidazolium, whose substituents in position 1 and 2 are methyls, the substituents in position 4 and 5 are hydrogen atoms, comprises a substituent in position 3 independently selected among the alkyl, fluorinated alkyl, perfluorinated alkyl, alkyl silane, alkyl alcohol or vinyl groups having a linear chain or a branched chain with 1 to 3 carbon atoms. 
     
     
         25 . Method according to  claim 15 , in which said 
       
         
           
           
               
               
           
         
         sulfonylimide corresponds to the following general formula: 
         in which R 1  and R 2  are identical or different and independently selected among a fluoroalkyl, fluoroether, perfluorinated alkyl or perfluoroether group, such as [(CF 3 SO 2 ) 2 N] − , [(CF 3 CF 2 SO 2 ) 2 N] − , [(CF 3 CF 2 CF 2 CF 2 SO 2 ) 2 N] −  or [(CF 3 CF 2 CF 2 SO 2 ) 2 N] − . 
       
     
     
         26 . Method according to  claim 25 , in which said sulfonylimide corresponds to [(CF 3 SO 2 ) 2 N] − , [(CF 3 CF 2 SO 2 ) 2 N] − , [(CF 3 CF 2 CF 2 CF 2 SO 2 ) 2 N] −  or [(CF 3 CF 2 CF 2 SO 2 ) 2 N] − . 
     
     
         27 . Method according to  claim 15 , in which the ionic liquid or at least one of the ionic liquids of the mixture is selected among:
 3-(2-hydroxyethyl)-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide;   3-(2-hydroxypropyl)-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide;   1-ethyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide;   1-ethyl-2,3-dimethylimidazolium bis(pentafluoroethylsulfony)imide;   3-allyl-1,2-dimethylimidazolium bis(trifluoromethylsulfonyl)imide;   1,2-dimethyl-3-(trimethylsilyl)methyl)imidazolium bis(pentafluoroethylsulfony)imide;   1,2-dimethyl-3-((trimethylsilyl)methyl)imidazolium bis(trifluoromethylsulfonyl)imide;   1,2-dimethyl-3-((trimethylsilyl)propyl)imidazolium bis(trifluoromethylsulfonyl)imide;   2,3-dimethyl-1-propylimidazolium bis(pentafluoroethylsulfony)imide   2,3-dimethyl-1-propylimidazolium bis(trifluoromethylsulfonyl)imide;   2,3-dimethyl-1-propylimidazolium 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonylimide;   3-(2-methoxyethyl)-1,2-dimethylimidazolium bis(pentafluoroethylsulfony)imide;   3-(2-methoxyethyl)-1,2-dimethylimidazolium bis(trifluoromethylsulfonyl)imide;   2,3-dimethyl-1-propanolimidazolium bis(trifluoromethylsulfonyl)imide;   1,2 dimethyl-3-allylimidazolium bis(trifluoroethylsulfonyl)imide;   1-propyl-3,5-dimethylpyridinium bis(trifluoromethyl)sulfonyl)imide;   1-(2-hydroxyethyl)-3,5-dimethylpyridinium bis(trifluoromethyl)sulfonyl)imide;   ethyldimethylpropylammonium bis(trifluoromethylsulfonyl)imide;   N-ethyl-2-hydroxy-N,N-dimethylethaneammonium bis(trifluoromethylsulfonyl)imide;   N-ethyl-2-hydroxy-N,N-dimethylethaneammonium bis(pentafluoroethylsulfonyl) imide;   N-(2-hydroxyethyl)-N,N-dimethylpropaneammonium bis(trifluoromethylsulfonyl) imide;   1-propyl-4-methylpyridin-1-ium bis(trifluoromethylsulfonyl)imide;   1-ethyl-3-methylpyridin-1-ium bis(trifluoromethylsulfonyl)imide;   1-propyl-3,5-dimethylpyridinium bis(trifluoromethylsulfonyl)imide;   1-(2-hydroxyethyl)-3,5-dimethylpyridinium bis(trifluoromethylsulfonyl)imide;   or a mixture thereof.   
     
     
         28 . Method according to  claim 15 , in which the lubricating composition comprises at least 50% to 100% of said ionic liquid with respect to the total mass of the lubricating composition. 
     
     
         29 . Method according to  claim 28 , in which the lubricating composition comprises at 75 mass-% to 100 of said ionic liquids with respect to the total mass of the lubricating composition. 
     
     
         30 . Method according to  claim 15 , in which the lubricating composition comprises from 0 mass-% to 25 mass-% of one or of several additives with respect to the total mass of the lubricating composition. 
     
     
         31 . Method according to  claim 30 , in which the additive or the additives are selected from: anti-wear agents, anti-corrosion agents, antioxidants, and a mixture of two or more of these additives. 
     
     
         32 . Method for reducing the deposits formed in a machine by using a lubricating composition, in which said lubricating composition comprises, by mass with respect to its total mass, from 20% to 100% of an ionic liquid or of a mixture of several ionic liquids,
 said ionic liquid or said mixture of ionic liquids being selected from an ionic liquid or a mixture of ionic liquids comprising at least:   an anion A− chosen from sulfonylimides, the substituent(s) of which is (are) independently chosen from a fluoroalkyl, fluoroether, perfluorinated alkyl, perfluoroether or perfluorosulfonyl group, and   a cation C+ comprising a nitrogen-containing heterocycle or a quaternary ammonium, the substituent(s) of which is (are) independently chosen from: a hydrogen atom or alkyl, alkoxy, fluorinated alkyl, perfluorinated alkyl, alkylsilane, alkyl alcohol, vinyl, alkyl allyl, ether or polyether groups having a linear or branched chain having from 1 to 3 carbon atoms, on condition that when the cation is a quaternary ammonium, at least two of these substituents are a methyl group,   the deposition start temperature (TDD) in thin film, determined by the MCT method according to the standard GFC Lu-27 A-13, of the ionic liquid or of the mixture of ionic liquids is at least equal to 330° C.   
     
     
         33 . Method according to  claim 32 , wherein the deposition start temperature (TDD) in thin film, determined by the MCT method according to the standard GFC Lu-27 A-13, of the ionic liquid or of the mixture of ionic liquids is higher than or equal to 350° C. 
     
     
         34 . The method of  claim 20 , wherein the cation C +  is a pyridinium comprising at least one methyl group at position 3, 4 or 5.