Patent ID: 7750098

Claim:
A method of manufacturing, by suspension polymerization, dielectric terpolymers, the method comprising: injecting an initial mixture of constituent monomers into an autoclave at constant temperature and pressure, the mixture of constituent monomers comprises vinylidene difluoride (VDF), trifluoroethylene (TrFE), and 1,1-chiorofluoroethylene (CFE); and continuously injecting at constant pressure, as soon as the polymerization is initiated and throughout the duration of polymerization, a second mixture of the constituent monomers, the monomers of the second mixture being injected in a critical phase and being compressed to a pressure of between 80 and 100 bars, wherein the molar composition of the initial mixture and the second mixture are determined by calculation, in a manner known of itself, taking into account the desired molar composition of the terpolymer and the higher reactivity of CFE in the critical phase, the terpolymer obtained is composed of x mol % VDF, y mol % TrFE and (100-x-y) mol % CFE, where x is between 40 and 70, and the sum of x and y is between 90 and 95, and the amount of CFE in the initial monomer mixture is less than 1.5 mol %.