Multiple emulsions
AssigneeWacker Chemie AG
InventorsHerbert Barthel, Bernard Paul Binks, Amro Dyab, Paul Fletcher
Life of this patent
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Abstract
Storage stable multiple emulsions of a polar phase A1, a nonpolar phase B and a polar phase A2, or of a nonpolar phase B1, a polar phase A and a nonpolar phase B2, employ particulate solids smaller than 1 μm to stabilize the resulting A1/B/A2 or B1/A/B2 multiple emulsions against coalescence, with the proviso that surface-active substances are present only up to a maximum concentration of less than 0.1 times the critical micelle concentration of the surface-active substances in phase A, A1, A2. The multiple emulsions have numerous uses including controlled release of active substances from a dispersed phase.
Claims14
A multiple emulsion which is stable against coalescence, comprising a composition A1/B/A2 or B1/A/B2, wherein A, A1, and A2 are polar phases and B, B1, and B2 are non-polar phases, and at least first and second particulate silica dispersants, each having mean particle sizes less than 1 μm, the first silica dispersant wettable by a phase A, A1, or A2 contained in the multiple emulsion and also wettable by a phase B, B1, or B2 contained in the multiple emulsion, the second silica dispersant wettable by a phase B, B1, or B2 contained in the multiple emulsion, but not wettable by a phase A, A1, or A2 contained in the multiple emulsion, said multiple emulsions prepared by a process comprising:
- a) when the multiple emulsion is an A1/B/A2 multiple emulsion, preparing an A1/B emulsion by emulsifying A1 into B in the presence of said second silica dispersant, dispersing said first silica dispersant in A2, and dispersing the A1/B emulsion into A2, forming an A1/B/A2 multiple emulsion, or
- b) when the multiple emulsion is a B1/A/B2 multiple emulsion, preparing a B1/A emulsion by emulsifying B1 into A in the presence of said first silica dispersant, dispersing said second silica dispersant into the B2 phase, and dispersing the B1/A emulsion into B2, forming a B1/A/B2 multiple emulsion,
- wherein the multiple emulsion contains less than or equal to 0.1 times the critical micelle concentration of surface active substances in the polar phases A, A1, and A2, such that in the absence of said silica dispersants, a multiple emulsion containing less than or equal to 0.1 times the critical micelle concentration of surface active substances exhibits coalescence.
Dependencies are inferred from the claim text.