Microencapsulation of particles using supercritical carbon dioxide

In this contribution a novel fluidized-bed coating process is introduced to encapsulate heat-sensitive materials with particle sizes below 100 µm. Supercritical carbon dioxide is used as solvent for the coating material as well as carrier fluid for the core material. The behaviour of the high pressure fluidized-bed was investigated for different process parameters and materials. It is shown that the fluidization starts at lower fluid velocities if the pressure is increased and it was possible to fluidized particles with a mean size below 10 µm. The coating of glass beads with stearyl alcohol was carried out and layers with a thickness of 1-8 µm were achieved.