The present invention is concerned with colloidal products containing boron and phosphorus soluble in mineral oils and obtained by reacting at least one phosphorus sulphide with at least one alkali metal sulfonate or alkaline-earth sulfonate known as an overbased sulfonate, which has first of all been borated.
The present invention is also concerned with the use of these products as additives in mineral and synthetic lubricating bases. In fact, the colloidal compounds according to the invention are excellent anti-wear additives and extreme-pressure additives which can be used in the formulation of engine oils, gearing oils, hydraulic fluids, lubricants for working metals, lubricating fats, and, generally speaking, when a lubrication problem demands a high lubricating capacity combined with excellent thermal stability.
In French Patent No. 2.645.168, a description is given of the preparation of thiophosphorated compounds by the reaction of at least one phosphorus sulfide with at least one detergent additive called an overbased additive. Generally speaking, an overbased detergent additive can be defined as being constituted of a surface-active agent consisting mainly of an alkali salt or alkaline-earth salt of an acid compound containing oleophilic groups, and which, in colloidal dispersion, maintains low mineral acid salts such as CO.sub.2, H.sub.2 S and alkali or alkaline-earth bases. Furthermore, in that French Patent Application, the reaction product between the phosphorus sulfide and the highly basic detergent additive can be treated subsequently with at least one compound containing active hydrogen which can be water, alcohol, a phenol, an acid, ammonia, an amine, an amide and/or a mercaptan.