MELAMINE FORMALDEHYDE MICROENCAPSULATION IN AQUEOUS SOLUTIONS CONTAINING HIGH CONCENTRATIONS OF ORGANIC SOLVENT

摘要

A process for making melamine-formaldehydemicrocapsules in an aqueous solution containing a highconcentration of a water miscible or water soluble organicsolvent is provided. The aqueous solution is prepared anda water insoluble melamine-formaldehyde pre-condensate isdissolved therein by adjusting the temperature and organicsolvent concentration of the aqueous solution such thatthe melamine-formaldehyde pre-condensate is barely solubletherein. A substance to be encapsulated, preferably anoily solution containing a dyestuff precursor, isdispersed into the aqueous solution to form an emulsion,the melamine-formaldehyde pre-condensate being insolublein the substance to be encapsulated. Themelamine-formaldehyde pre-condensate is separated from the aqueoussolution onto droplets of the substance to be encapsulatedand the self-condensation reaction of the phase-separatedmelamine-formaldehyde pre-condensate initiated to formcapsule walls around the droplets, thereby producingmelamine-formaldehyde microcapsules in the aqueoussolution containing a high concentration of a watermiscible or water soluble organic solvent.