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 fluid bed. Many kinds of composite particles prepared by a fluid 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-flowing coarse particles, but their coating for forming multilayered structures without core-particle agglomeration is difficult, because of the adhesive and cohesive properties of such fine particles.1 So, liquid-phase processes, including emulsifying processes and phase separation, have been applied to make fine composite particles. In this section, the fluid bed process2 and the emulsifying process are described, mostly with examples limited to the pharmaceutical field, since the methods and applications are diverse among industrial fields.
