Preparation of magnesium borate succinimide and its characteristics as a lubricating oil additive

Abstract

AbstractSuccinimide has for a long time been widely used for ashless dispersants in engine lubricating oils. However, this kind of dis‐persant does not have particularly good antioxidant, antifriction, antiwear or acid neutralisation properties. In this paper, a method is suggested for modifying succinimide so as to obtain improved antioxidant, acid neutralisation, antifriction, and antiwear properties.Magnesium borate cannot be dissolved in mineral lubricating oil. In the presence of succinimide, however, it will exist in a lubricating oil in the form of a colloid or complex. Therefore, in the present work, magnesium oxide, boric acid, and water were mixed together with succinimide. In the reaction process, some of the magnesium borate formed in situ will be surrounded by succinimide, forming stable colloids; the remainder will react with the succinimide, forming well distributed complexes in the lubricating oil. The presence of water is very important for this process. At least four moles of water are needed for one mole of magnesium borate.The resulting material has been evaluated as a lubricating oil additive. The experiments have shown that this kind of material possesses good antioxidant, acid neutralisation, antifriction, and antiwear properties, apparently due to the introduction of magnesium borate. The introduction of the magnesium borate does not influence the good dispersant properties of the succinimide.