method of isolating microcapsules from aqueous dispersions Russian patent published in 1998 - IPC

FIELD: encapsulated materials. SUBSTANCE: invention relates to technology of microencapsulation of fine particles of target substances and compositions and, more particularly, to methods for isolation from aqueous dispersions of microcapsules up to 1 mcm in size, whose shells do not contain impurities, e.g. demulsifiers. Such microcapsules are necessary for manufacturing color photographic materials, information registration and processing systems, and printing inks with specific optical effects. Principal task of invention consists in increasing purity degree of shells of microencapsulated substances. To this end, separation of dispersion of microcapsules is accomplished with no aid of organic-originated demulsifiers, but in presence of mineral salts' (sodium carbonate and zinc sulfate) solutions, in the course of chemisorption and then chemical interaction of which, water-insoluble zinc carbonate coating is formed on shells of microcapsules caused by exchange reactions. Microcapsules are then filtered off from dispersion medium and washed out directly on filter with diluted (0.5- 1%) sulfuric acid to remove zinc carbonate, after which they are dried at 40 C for 1 h. Microcapsules obtained are compatible with various binding agents and can be applied with no further processing. EFFECT: facilitated separation of microcapsules with improved shell purity.