Patent ID: 8394748

Claim:
A grease composition produced by a process which comprises kneading a mutually incompatible mixture of 25-95 vol. % of a thickener-containing non-fluorine-based base oil comprising at least one of ester-based synthetic oils and synthetic hydrocarbon oils as the base oil and at least one of metallic soaps, metallic complex soaps and urea-based compounds as the thickener, and 75-5 vol. % of a thickener-containing fluorine-based base oil comprising a perfluoropolyether represented by the general formula: RfO[CF(CF 3 )CF 2 O] s Rf where Rf is perfluoro lower alkyl groups having 1-5 carbon atoms, s=2-200, as the base oil and fluororesins as the thickener, the proportion of thickeners in total being in a range of more than 30 vol. % to not more than 50 vol. % in the composition, through a three-roller mill at least twice, wherein the base oils are in a morphological structure and where one of the base oils is homogeneously dispersed in a particulate state in an average particle size of not more than 30 μm as a dispersed phase in a sea-island structure in the other base oil in a continuous phase.