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AssigneeAllied Colloids Limited
InventorsJohn G. Langley, Kenneth C. Symes, Kishor K. Mistry
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This invention relates to the encapsulation of active ingredient within polymeric material so as to protect the active ingredient from the ambient environment, for instance atmospheric moisture when the product is exposed to the air, or the liquid phase of a liquid detergent when the product is incorporated in such a detergent. A dispersion in oil of an aqueous solution of a matrix polymeric material containing enzyme or other active ingredient is subjected to distillation to provide a substantially anhydrous dispersion in oil of particles of matrix polymer containing active ingredient, and during or after the distillation the polymer solution is converted into a solid polymer. In the invention, we use a matrix polymer that is so hydrophobic that it partitions preferentially into the oil rather than into the aqueous solution of encapsulating polymer. Because the aqueous solution is incompatible with both the hydrophobic oil and the matrix polymer, there is increased tendency for the encapsulating shell to be formed around a layer of oil, rather than in direct contact with a matrix polymer particle.
A particulate composition comprising particles having a substantially anhydrous core comprising one or more particles of a matrix polymer containing active ingredient and a layer of hydrophobic oil around the matrix polymer particle or particles, and a coacervate shell around the oil layer formed by coacervation of coacervate polymer wherein the solid matrix polymer is sufficiently hydrophobic that it will partition preferentially into the oil rather than into water.
A process for producing encapsulated particles comprising selecting a matrix polymer, providing a dispersion in oil of an aqueous solution of the matrix polymer containing active ingredient, subjecting this dispersion to distillation to provide a substantially anhydrous dispersion in oil of particles of matrix polymer containing active ingredient and during or after the distillation converting the matrix polymer into a solid polymer, providing an aqueous solution of encapsulating polymeric material that can be caused to deposit as a solid shell about particles dispersed in the solution, dispersing the substantially anhydrous dispersion of matrix polymer particles containing active ingredient in oil into the aqueous solution and causing a solid coacervate polymer shell to form around droplets of the matrix particles in oil, wherein the polymer which is selected as matrix polymer is a polymer which partitions into the oil in preference to the aqueous solution of encapsulating polymeric material.
A process for producing encapsulated particles comprising selecting a matrix polymer, providing an aqueous solution of encapsulating polymeric material that can be caused to deposit as a solid shell about particles dispersed in the solution, providing a substantially anhydrous dispersion in oil of particles of the matrix polymer containing active ingredient, dispersing this substantially anhydrous dispersion of matrix polymer particles containing active ingredient in oil into the aqueous solution, and causing a solid coacervate polymer shell to form around droplets of the matrix particles in oil, and in which the selected matrix polymer partitions into the oil in preference to the aqueous solution of encapsulating polymeric material.
Dependencies are inferred from the claim text.