Bearing having low torque, small noise and long life

摘要

A bearing with which low torque property, low noise property and low volatilization property can be maintained, is provided. The bearing is sealed with a grease composition comprising:(A) an alkali metal salts and/or an alkaline earth metal salt synthesized from a hydroxide of an alkali metal or an alkaline earth metal, and a higher fatty acid having 10 or more carbon atoms or a higher hydroxyfatty acid having at least one hydroxyl group and 10 or more carbon atoms;(B) a carbonate compound represented by the general formula: (R and R' represent a branched alkyl group having 13-15 carbon atoms, and may be same or different); and(C) at least one kind of an ester-based synthetic oil selected from the group consisting of a diester-based synthetic oil represented by the general formula (i):        ROCO(CH2)nCOOR'     (i)(R and R' represent an alkyl group having 3-18 carbon atoms, and may be the same or different, and n is 3-12);a triester-based synthetic oil represented by the general formula (ii):        C2H5C(CH2OCOR)3     ii(R represents an alkyl group having 3-10 carbon atoms);a tetraester-based synthetic oil represented by the following general formula (iii):        C(CH2OCOR)4     (iii)(R represents an alkyl group having 3-10 carbon atoms), and other neopentyl polyol ester-based synthetic oil.