Pigment Red 60 micronization using supercritical fluids based techniques

The production of micrometric particles of Disperse Red 60 pigment was studied using two supercritical fluids based techniques: the supercritical antisolvent precipitation (SAS) and the supercritical assisted atomisation (SAA). We studied the influence of some process parameters on the final product: the variation of the dye concentration in the solvent using the SAS technique, and supercritical fluid/liquid solvent flow ratio, temperature and concentration in the liquid solution using SAA technique. These parameters allow the control of the particle size of the produced powders. Using SAS, we obtained Disperse Red 60 as spherical nano-particles with mean diameters ranging between 50 and 100nm. Very long needle-like crystals were also obtained at some process conditions. Using SAA, quasi-spherical crystals with mean diameters ranging between 0.5 and 2.5 mu m were produced. Therefore, in the case of Disperse Red 60, the two processes demonstrate to be complementary: nanometric particles can be obtained using SAS, whereas micrometric particles are produced using SAA. (c) 2004 Elsevier B.V. All rights reserved.