Automatic transmission and wet brake fluids and additive packages therefor

摘要

Oil-based functional fluid compositions formulated for use as automatic transmission fluid, fluid for a wet brake system, or a friction-depending lubricant are improved by including in the composition a minor amount of at least one alcohol or polyol having less than 12 carbon atoms in the molecule. This results in a desirable increase in the dynamic and/or static coefficients of friction of automatic transmission or other frictional surfaces contacted by the composition. Preferred for this use is a composition formed by heating at least one ashless dispersant containing basic nitrogen and/or at least one hydroxyl group with a combination of at least (i) an inorganic acid of phosphorus, (ii) a boron compound, and (iii) a polyol having less than 12 carbon atoms, so that a liquid composition is formed. The boron compound and the inorganic phosphorus acid are preferably co-present during the heating. However either such substance can be added and subjected to the heating step after the other provided that the conditions used result in the formation of a clear, liquid composition.