GB587258A - An improved manufacture of lubricating greases - Google Patents

Abstract

Lubricating grease is prepared by dissolving fats, fatty acids or naphthenic acids in mineral oil and saponifying them with a dispersion of metal oxide or hydroxide in an inert liquid. The dispersion is one prepared by suspending the metal oxide or hydroxide in the inert liquid and mechanically comminuting till the particle size is predominantly 5m or less. Fats mentioned are mutton tallow and beef stearin while fatty acids mentioned are stearic acid, oleic acid, cottonseed oil fatty acids and synthetic fatty acids obtained by the oxidation of high molecular weight substantially saturated hydrocarbons such as paraffin wax. Mixtures of the saponifiable materials may be employed and lower fatty acids such as acetic or butyric acid may be incorporated with the saponifiable materials. The saponifying agent may be caustic soda, caustic potash, lithium hydroxide, calcium hydroxide, barium hydroxide, magnesium hydroxide, lead oxide (PbO), nickel oxide, cobalt oxide, or manganese oxide (MnO), but mixtures may also be employed. The inert liquid in which the saponifying agent is suspended may be mineral oil but lighter fractions such as fuel oils, naphthas and more volatile products may be used. If desired, the comminuted dispersion of saponifying agent in mineral oil may be diluted with an inert volatile diluent such as petroleum, naphtha of a liquefied gaseous hydrocarbon such as pentane, butane or propane, so that only the ultra-fine particles stay in suspension. After settling or centrifuging, the volatile diluent is distilled off and the fractionated dispersion thus obtained used for saponification. Alternatively the original dispersion may be made in one of the inert volatile diluents mentioned above. During comminution of the saponifying agent, a small amount of sodium stearate, sodium oleate, stearic acid, oleic acid or other similar soaps or fatty acids may be added to prevent coagulation or agglomeration of the finely divided particles. The final grease may be put through a colloid mill and may be subjected to further cooking to evaporate moisture or to distil off glycerine resulting from the saponification reaction. In examples, comminuted dispersions of caustic soda in mineral oil are heated with solutions of stearic acid, oleic acid, mutton tallow or cottonseed oil fatty acids in mineral oil to produce lubricating greases.