ABSTRACT
Abbreviations ................................................................................................................................. 111 Unit Conversions ............................................................................................................................ 112 7.1 Introduction.......................................................................................................................... 112 7.2 History .................................................................................................................................. 112 7.3Process Descriptions ............................................................................................................. 113
7.3.1 Fluidization ............................................................................................................... 113 7.3.2Wurster (Bottom Spray) Fluid Bed Coating ............................................................. 115 7.3.3Spouted Bed .............................................................................................................. 118 7.3.4Top Spray.................................................................................................................. 119 7.3.5Tangential Spray (Rotary) Granulation .................................................................... 119
7.4 Parameter Assessment .......................................................................................................... 120 7.4.1Process Air ............................................................................................................... 120
7.4.1.1Spouted Bed, Top Spray, and Tangential Spray Process Air ..................... 121 7.4.1.2Wurster Process Air ...................................................................................124 7.4.1.3Process Air Temperature and Volume Relationship .................................. 129
7.4.2 Nozzles and Atomization .......................................................................................... 131 7.4.3 Temperature .............................................................................................................. 133
7.4.3.1Process Temperatures ................................................................................ 133 7.4.3.2Hot Melt Temperatures .............................................................................. 134
7.4.4Drying Capacity........................................................................................................ 135 7.4.5 Tangential Spray Rotor Speed .................................................................................. 140
7.5 Application............................................................................................................................ 140 7.5.1Processing Obstacles ................................................................................................ 140 7.5.2Practical Considerations ........................................................................................... 141 7.5.3Commercial Applications ......................................................................................... 142
7.5.3.1 Coating Ingredients .................................................................................... 142 7.5.3.2Application Areas and Coat Functions ...................................................... 142
References ...................................................................................................................................... 144
°K degrees Kelvin min minute mg milligram mm millimeter psipounds per square inch scfm cubic feet per minute at standard pressure and temperature s seconds Tgglass transition temperature µm micrometer
°C = (°F − 32)/1.8 1 in. = 2.54 cm 1 m = 3.28 ft
Fluidized bed coating technology refers to processes where solid particulate material is uidized in relation to coating spray from a nozzle or nozzles to apply a coating on the particulate. In the context of this publication, the coatings provide a controlled-release property to either the core particle or some element of the applied coating. The following processes are addressed to varying extents in this work:
Wurster (bottom spray) uid bed coating Spouted bed coating Top spray granulation Tangential spray (rotary) granulation
Other related processes exist and may have found some level of commercial success, but they are not addressed directly in this chapter. The principles that are addressed can generally be applied to any uid bed coating process.
