Precipitation of microparticulate organic pigment powders by a supercritical antisolvent process

The supercritical antisolvent (SAS) process has been used to produce submic ronic Bronze Red particles. Among the process parameters, the pressure, tem perature, and flow rate of the solution were studied. Two different solvent s, ethanol and acetone, were also studied. The concentration of the liquid solution was kept unchanged in all of the experiments. The size and morphol ogy 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 tempera ture and pressure but were influenced only by the flow rate. It was indicat ed that the interaction between the solute and the solvent played an import ant role in controlling the morphology and size of the crystals of Bronze R ed under the same concentration.