FINE PARTICLES PREPARATION OF RED-LAKE-C PIGMENT BY SUPERCRITICAL-FLUID

Fine material preparation for several kinds of pigments (Red Lake C, C .I. Pigment Blue and C.I. Pigment Yellow) was investigated under super critical conditions. In the experiments, acetone was used as solvent a nd carbon dioxide as anti-solvent were applied in the recrystallizatio n processes. To obtain the ultrafine particle products, a series of 5- 500 mu m nozzles were used to disperse the solution out from the cryst allizer. Experimental results showed that operations under supercritic al conditions were able to provide very small particles, e.g. less tha n 1 mu m in diameter, very narrow size distribution and spherical morp hology. Further study also showed that the particle size could be cont rolled by temperature, pressure and nozzle size. (C) 1998 Elsevier Sci ence B.V.