Patent ID: 6391326
Filing Date: 2002-05-21
Classification: A61L,C08J,Y10S,Y10T

Abstract:
Stable emulsion of at least one chemical substance x in an elastomer solution, which can be used for the preparation of an elastomeric film, comprising (1) a phase A comprising an elastomer dissolved in an apolar or relatively nonpolar organic solvent a, in which is dispersed (2) a phase B comprising at least said chemical substance x dissolved or dispersed in a polar solvent b, which is immiscible with the phase A, and (3) at least one dispersing agent selected from the group consisting of block copolymers and grafted copolymers, wherein:the droplets of dispersed phase B have a diameter &gE;10 &mgr;m, said emulsion comprises, for the stabilization of said dispersed phase B, besides at least one dispersing copolymer comprising polyA sequences which are compatible with phase A and polyB sequences which are compatible with phase B, at least one particulate stabilizer selected from the group consisting of solid organic compounds of between 30 nm and 10 &mgr;m in size and solid inorganic compounds of between 5 nm and 10 &mgr;m in size, whose surface is organophilic in nature, the mass fraction &phgr;B of dispersed phase (phase B) in the emulsion, expressed by: Ï†B=mBmB+mA+melastomerâ€ƒis between 0.01 and 0.2, with mB=mass of phase B (solvent b+active chemical substance x) mA=mass of solvent a melastomer=mass of the elastomer dissolved in a; the mass fraction of the block or grafted copolymer, &phgr;DC, expressed relative to the dispersed phase B: Ï†DC=mD&it;â€ƒ&it;CmD&it;â€ƒ&it;C+mBâ€ƒis between 0.001 and 0.3, with mB=mass of phase B mDC=mass of dispersing copolymer; and the mass fraction of particulate stabilizer (PS) &phgr;PS, formed in situ or added as an adjuvant, expressed relative to the dispersed phase B: Ï†PS=mPSmPS+mBâ€ƒis between 0.001 and 0.5, with mPS=mass of particulate stabilizer mB=mass of phase B.