Process for treating a material chosen from among a polyamide, a polyester and a poly(meth)acrylate

A process for the treatment of a material of a component of an electrical appliance to impart improved moisture resistance properties to the material, the material being chosen from among a polyamide, a polyester and a poly(meth)acrylate, the process comprising:

• a first step in which contact is made between the material and a polar organic solvent in a first supercritical fluid, and
• a second step of bringing the material as obtained at the end of the first step into contact in a second supercritical fluid with one or several compounds soluble in the second supercritical fluid and each satisfying the following formula (I):
• R—(N═C═O)n (I)
• wherein
• n is equal to 1 or 2, and
• R is chosen from among
• a saturated or unsaturated, linear or branched, aliphatic hydrocarbon group comprising at least 2 carbon atoms, and
• a saturated or unsaturated, possibly branched, cyclic aliphatic hydrocarbon group comprising at least 3 carbon atoms.