Stable emulsions, preparation methods and applications

Abstract

The invention concerns stable emulsions, a method for preparing said emulsions and the elastomer films containing them. Said stable emulsions of at least one chemical substance x in an elastomer solution, to be used for preparing an elastomer film, comprise (1) a phase A containing an elastomer dissolved in an organic apolar or slightly polar solvent a, wherein is dispersed (2) a phase B containing at least said chemical substance x, in solution or dispersed in a polar solvent b, non-miscible with phase A and (3) at least a dispersing agent selected from the group consisting of block or grafted polymers. Said emulsions are characterised in that the dispersed phase B droplets have a diameter ≧10 &mgr;m; said emulsion comprises, for stabilising said dispersed phase B, besides at least one dispersing copolymer comprising poly A sequences, compatible with phase A and poly B sequences compatible with phase B, at least a particulate stabiliser selected from the group consisting of solid organic compounds of dimension ranging between 30 nm and 10 &mgr;m, or solid mineral compounds of dimension ranging between 5 nm and 10 &mgr;m, whereof the surface state is organophilic; the mass fraction ø of the dispersed phase (phase B) in the emulsion ranges between 0.01 and 0.2; the mass fraction of block or grafted copolymers, ø , expressed relative to dispersed phase B ranges between 0.001 and 0.3, preferably between 0.01 and 0.2 and the mass fraction of particulate stabiliser (SP), ø , expressed relative to dispersed phase B ranges between 0.001 and 0.5.