Grease composition

Abstract

The disclosure relates to a grease composition comprising: (A) a synthetic base oil in majority consisting of alkylaromatic(s); (B) a thickener in majority consisting of at least one metal soap of fatty acids; and (C) a solid lubricant in majority consisting of nanoparticulate polytetrafluorethylene, at least 85% of the particles of which have a size of less than one micron.

1 . A grease composition comprising:
 (A) a synthetic base oil in majority consisting of alkylaromatic(s);   (B) a thickener in majority consisting of at least one metal soap of fatty acids; and   (C) a solid lubricant in majority consisting of nanoparticulate polytetrafluoroethylene, at least 85% of the particles of which have a size of less than one micron.   
     
     
         2 . The composition according to the preceding claim, wherein the oil in the form of alkylaromatics makes up at least 80% by weight of the base oil in said composition. 
     
     
         3 . The composition according to  claim 1 , wherein the metal soap(s) make(s) up at least 80% by weight of the thickener in said composition. 
     
     
         4 . The composition according to  claim 1 , wherein the solid lubricant consists of at least 80%, by weight of nanoparticulate polytetrafluoroethylene. 
     
     
         5 . The composition according to  claim 1 , wherein the solid lubricant only consists of nanoparticulate polytetrafluoroethylene. 
     
     
         6 . The composition according to  claim 1 , wherein the thickener is free of urea compounds. 
     
     
         7 . The composition according to  claim 1 , wherein the composition is free of calcium carbonate. 
     
     
         8 . The composition according to  claim 1 , wherein the composition comprises 0.1 to 10% by weight of solid lubricant in the form of nanoparticulate polytetrafluoroethylene. 
     
     
         9 . The composition according to  claim 1 , wherein the polytetrafluoroethylene particles have an average size comprised between 150 and 800 nm. 
     
     
         10 . The composition according to  claim 1 , wherein the synthetic base oils are selected from oils of the alkybenzene or alkylnaphthalene type. 
     
     
         11 . The composition according to  claim 1 , wherein the synthetic base oil comprises at least one other mineral, synthetic or natural base oil. 
     
     
         12 . The composition according to  claim 1 , wherein the soaps are simple metal soaps of either saturated or not, either hydroxylated or not, fatty acids comprising from 14 to 28 carbon atoms, or complex metal soaps of one or more either saturated or not, either hydroxylated or not fatty acids comprising from 14 to 28 carbon atoms, in a combination with one or more carboxylic acids with a short hydrocarbon chain comprising from 6 to 12 carbon atoms. 
     
     
         13 . The composition according to  claim 1 , wherein the metal soaps of fatty acids are selected from titanium, aluminium, alkaline and earth alkaline metal soaps, preferably lithium, calcium, sodium, barium soaps. 
     
     
         14 . The composition according to  claim 1 , wherein the composition comprises one or more anti-wear and/or extreme pressure agents. 
     
     
         15 . The grease composition according to  claim 1 , wherein the composition comprises, based on the total weight of the composition:
 from 50 to 90% by weight of the synthetic base oil;   from 1 to 15% by weight of the thickener in majority consisting of at least one metal soap of fatty acids;   from 0.1 to 10% by weight of solid lubricant in the form of nanoparticulate polytetrafluoroethylene powder with at least 85% of the particles which have a size of less than one micron; and   from 0 to 10% of one or more anti-wear and/or extreme pressure additives.   
     
     
         16 . The composition according to the preceding claim, wherein the composition comprises 5 to 15% by weight based on the total weight of the composition, of a synthetic oil of the polyalphaolefin type. 
     
     
         17 . The composition according to  claim 1 , wherein the composition comprises a base oil having a kinematic viscosity at 40° C., measured according to the ASTM D 445 standard, comprised between 10 and 120 mm 2 /s. 
     
     
         18 . The composition according to  claim 1 , wherein the composition has a consistency according to the ASTM D217 standard of more than 265 tenths of millimeters, and in that it has a consistency according to the ASTM D217 standard of more than 400 tenths of millimeters. 
     
     
         19 . A method for preparing a grease, the method comprising:
 dissolving one or more fatty acids in a fraction of the base oil or of the base oil mixture   adding metal compounds;   saponifying fatty acids with said metal compounds; and   incorporating nanoparticulate polytetrafluoroethylene, for which at least 85% of the particles have a size of less than one micron.   
     
     
         20 . The composition according to  claim 1 , wherein the grease is adapted for use in automobile transmissions. 
     
     
         21 . The composition according to  claim 1 , wherein the grease is adapted for use in at least one automobile member selected from: lubricated rolling bearings, machine tool slide rails or centralized greasing systems. 
     
     
         22 . The composition according to  claim 1 , wherein the solid lubricant consists of at least 90% by weight of nanoparticulate polytetrafluoroethylene. 
     
     
         23 . The composition according to  claim 1 , wherein it comprises 2 to 7% by weight of solid lubricant in the form of nanoparticulate polytetrafluoroethylene. 
     
     
         24 . The composition according to  claim 1 , wherein the composition has a consistency according to the ASTM D217 standard comprised between 265 and 475 tenths of millimeters, and has a consistency according to the ASTM D217 standard comprised between 400 and 475 tenths of millimeters.