| abstract |
A process is provided for preparing detergent-dispersant compositions of a TBN of at least about 200, containing at least about 2 percent magnesium, by: (1) sulfurization by sulfur of an alkylphenol in the presence of a magnesium and/or calcium alkylbenzene-sulfonate of a TBN less than or equal to about 150, an alkaline-earth component selected from among lime, mixtures of magnesium oxide and lime, or a magnesium oxide and alkali hydroxide, and an alkylene glycol; (2) optionally precarbonation of the resultant mixture by means of CO2; (3) super-alkalinization and carbonation of the resultant mixture by means of magnesium oxide and possibly lime, CO2 and alkylene glycol; and (4) removal of the excess alkylene glycol. The detergent-dispersant compositions obtained are useful in the improvement of the detergent-dispersant properties of lubricating oils. |