LUBE OIL COMPOSITION, OVERBASED ALKALINE EARTH METAL SULFIDE PHENEATE CONCENTRATE USED FOR PREPARING THE SAME, AND PROCESS FOR PREPARING THE CONCENTRATE

摘要

A lubricating oil composition having a high base value and an excellent high-temperature detergency and comprising an overbased alkaline earth metal phenate sulfide, and a process for producing an overbased alkaline earth metal phenate sulfide having a high base number and a viscosity at 100 DEG C of 1,000 cSt or less and is excellent in hydrolytic stability and oil solubility. And, the overbased alkaline earth metal phenate sulfide concentrate is produced by introducing an alkaline earth metal reagent, a phenol compound in an amount of from 1 to 100 equivalents per mol of the alkaline earth metal reagent, and sulfur into a reactor optionally together with water; adding a dihydric alcohol to the introduced mixture at a pressure inside the reactor of 10 to 250 kPa-G to react them; subsequently distilling off the excess dihydric alcohol and at least the excess amount of the water; treating the resultant bottom residue with carbon dioxide in the presence of from 0.3 to 0.8 mol of water per mol of the alkaline earth metal reagent; causing from 0.001 to 0.3 mol of a fatty acid compound to be present per mol of the alkaline earth metal reagent before the carbon dioxide treatment at the latest; and distilling off the excess phenol compound contained in the product of the carbon dioxide treatment.