ABSTRACT
Particles have been processed by various methods for composite particle formation depending on required size and function (Figure 4.1). Particles larger than 200 µm can be successfully processed by a fl uid bed. Many kinds of composite particles prepared by a fl uid bed are on the market; for example, most recent pharmaceuticals are composites for controlled drug release, including sustained release, prolonged release, delayed release, and taste masking. For smaller particles, agglomeration has been successfully carried out to get free-fl owing coarse particles, but their coating for forming multilayered structures without core-particle agglomeration is diffi cult, because of the adhesive and cohesive properties of such fi ne particles. 1 So, liquid-phase processes, including emulsifying processes and phase separation, have been applied to make fi ne composite particles. In this section, the fl uid bed process 2 and the emulsifying process are described, mostly with examples limited to the pharmaceutical fi eld, since the methods and applications are diverse among industrial fi elds.
