Precipitation of microparticulate organic pigment powders by a supercritical antisolvent process

The supercritical antisolvent (SAS) process has been used to produce submicronic Bronze Red particles. Among the process parameters, the pressure, temperature, and flow rate of the solution were studied. Two different solvents, ethanol and acetone, were also studied. The concentration of the liquid solution was kept unchanged in all of the experiments. The size and morphology of particles were affected by the temperature, pressure, and flow rate when ethanol was used as the solvent. Nevertheless, the size and morphology of the crystals precipitated from acetone were little sensitive to temperature and pressure but were influenced only by the flow rate. It was indicated that the interaction between the solute and the solvent played an important role in controlling the morphology and size of the crystals of Bronze Red under the same concentration.