摘要 |
An overbased metal salt of a hydrocarbyl-substituted sulphurised or non sulphurised phenol, a calixarene having a substituent hydroxyl group or groups available for reaction with metal base or a linear phenol/formaldehyde resin wherein the metal moiety comprises a first metallic component which is at least one alkaline earth metal and a second metallic component which is at least one of either (i) at least one alkali metal or (ii) at least one metal selected from Groups IIIa, IVa, Va, VIa, VIIa and VIII of either the first or the second transition series of the Periodic Table of the Elements, the weight ratio of the first metal component to the second metal component being in the range from 1000:1 to 2:1. |