Patent ID: 6113935
Filing Date: 2000-09-05
Classification: A01N,A61K,B01J

Abstract:
A process for the production of microcapsules containing an aqueous material within a polymeric shell, said process comprising:(a) providing an aqueous phase comprising a material to be encapsulated, and a urea-formaldehyde and/or melamine-formaldehyde prepolymer dissolved therein;(b) creating an emulsion of said aqueous phase in a continuous organic liquid phase comprising one or more organic solvents and one or more surface active agents, wherein the emulsion comprises discrete droplets of the aqueous phase dispersed in the continuous phase organic liquid, there being formed thereby an interface between the discrete droplets of the aqueous phase and the continuous organic liquid phase; and(c) causing in situ self-condensation of the prepolymer in the aqueous phase of the discrete droplets adjacent to the interface by heating the emulsion to a temperature of from about 20 to about 100.degree. C. in the presence of a surface active proton transfer catalyst which is soluble in the organic liquid but only slightly soluble in the aqueous phase for a sufficient period of time to allow substantial completion of in situ condensation of the prepolymer to convert the liquid droplets of the aqueous phase to microcapsules consisting of solid permeable polymer enclosing the aqueous material.