Patent ID: 8258089

Claim:
A grease composition comprising, as a base oil, 50 to 100% mass of the base oil of an ionic liquid formed of a cation and an anion and having an ion concentration of 1 mol/dm 3 or more as measured at 20° C., and a thickener, wherein the grease composition has a dropping point of 260° C. or higher, and wherein the ionic liquid is at least one selected from the group consisting of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluoroborate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, alkylpyridinium tetrafluoroborate, alkylpyridinium hexafluorophosphate, alkylpyridinium bis(trifluoromethanesulfonyl)imide, alkylammonium tetrafluoroborate, alkylammonium hexafluorophosphate, alkylammonium bis(trifluoromethanesulfonyl)imide, N,N-diethyl-N-methyl(2-methoxyethyl)ammonium tetrafluoroborate, N,N-diethyl-N-methyl(2-methoxyethyl)ammonium hexafluorophosphate, N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, and N,N-diethyl-N-methyl(2-methoxyethyl)ammonium bistetrafluoroborate.