To improve the oil solubility, storage stability, and heat stability, esp. high-temp. cleanness, of a petroleum additive based on an arom. hydroxycarboxylic acid alkaline earth metal salt by incorporating a higher aliph. carboxylic acid and a higher aliph. amine or a higher aliph. amide into the additive and by subjecting it to a specific sulfidization.
A 16-36C aliph. carboxylic acid (e.g. palmitic or stearic acid) in an amt. of 0.05-1.0mol per mol of an alkaline earth metal reagent is used as the higher aliph. carboxylic acid; a 16-36C prim. amine (e.g. hexadecylamine) in an amt. of 0.07-0.5mol per mol of the reagent, as the higher aliph. amine; and a 16-36C aliph. amide (e.g. palmitamide), as the higher aliph. amide. The sulfidization, which may be conducted at any step of the process for producing the petroleum additive, is conducted in the presence of elemental sulfur. When thus obtd. additive is added to a lubricating oil, it is added in such an amt. as to give the oil a base number of 5-80mgKOH/g. In the case of a diesel fuel oil, it is added in an amt. of 0.1-0.5wt.%, and in the case of a gasoline fuel for two-cycle engines, in an amt. of 0.01-1wt.%.
UEDA SANAE
IMAI JUN
COSMO OIL CO LTD