| abstract |
The invention concerns the use as extreme pressure additive in aqueous lubricants used for deforming or transforming metals, of lamellar crystallites having a length (L) ranging between 0.1 and 100 mu m, a width (I) ranging between 0.5 and 30 mu m and a thickness (e) ranging between 5 and 200 nm, comprising a stack of organic phases (O) and of aqueous solutions (A) in the sequence O/[A/O]n, n being an integer different from 0 and such that the stack has a thickness ranging between 5 and 200 nm, the organic phases comprising: i) at least an acid selected among: carboxylic acids, saturated or unsaturated, comprising at least 5 carbon atoms, acid phosphate esters of formula (RO)x-P(=O)(OH)x' wherein: R is a hydrocarbon radical, optionally polyalkoxylated, x and x' being equal to 1 or 2, provided that the sum of x and x' is equal to 3, said acid being optionally neutralised by an organic or mineral base; and at least a metal in the form of a multivalent ion; or (ii) at least a polyalkylene block polymer having a cloud point preferably ranging between 30 and 90 DEG C. The invention also concerns said lamellar crystallites and a method for obtaining them. |