1,048,696. Microcapsules. GEVAERT PHOTO-PRODUCTEN N.V. July 10, 1963 [July 11, 1962], No. 27402/63. Heading B8C. [Also in Division G2] Microcapsules, composed of a core of water, an aqueous solution or suspension or a hydrophilic material surrounded by a polymeric mantle, are prepared by emulsifying the core material in a solution of the polymeric material in a water-immiscible organic solvent having a boiling point below 100‹ C., dispersing the emulsion obtained to form an emulsion in an aqueous solution of an hydrophilic colloid and removing the solvent for the polymeric material by evaporation. Specified polymers are addition polymers and co-polymers formed from styrene, vinyl chloride, vinylidene chloride, vinyl esters, vinyl ethers, acrylic and methacrylic esters, acrylonitrile and methacrylonitrile; condensation polymers, e.g. polycarbonates, polyesters, polysulphonates, polyurethanes and polyamides and modified natural polymers, e.g. chlorinated rubber and cellulose derivatives, e.g. ethyl cellulose. Specified hydrophilic colloids are gelatine and gelatine derivatives, polyvinylalcohol, polystyrene sulphonic acid and hydroxyalkyl celluloses. The material to be encapsulated may be one which is useful as a fertilizer, plant growth hormone, pharmaceutical (e.g. vitamins), adhesive or a chemical useful in photographic processes. Specific examples relate to the encapsulation of water, thiourea, " Acid Magenta A ", aqueous sodium chloride and sodium hydroxide. Suitable organic solvents include benzene, methylene chloride and carbon tetrachloride.
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