Overview of Microencapsulation Process Technologies

Over two dozen processes exist for the preparation of microcapsules. Common processes include atomization, spray coating, coextrusion, and emulsion-based systems. Examples of these four categories include spray drying, fluid-bed coating, vibrating nozzle coextrusion, and complex coacervation. These processes cover a wide range of particle sizes, payloads, morphologies, production capacities, cost, and materials. Collectively, the technologies enable the production of capsules from tens of nanometers to millimeters in diameter with payloads up to 99%. Microsphere matrix particles or core–shell microcapsules can be commercially produced at capacities of several tons per hour to encapsulate solids and liquids with a variety of shell materials. Proper process selection is dependent on the specific parameters of a designed microcapsule.