1998 Volume 58 Issue 3 Pages 97-105
In the granule coating method using a centrifugal fluidized bed rotary granulator, cracking and abrasion of core particles is often caused by the spray air. A three-fluid nozzle spray gun, which has one more air line added to the outside of a two-fluid nozzle spray gun, was effective in reducing these problems. We developed a three-fluid nozzle spray gun, equipped at the centrifugal fluidized bed rotary granulator, and performed granule coating. As the result, use of the new spray gun prevented loss of yield, increased blocking and decrease of drug contents, and made it possible to produce high quality granules. The cracking and abrasion of particles were remarkably reduced by the effect of the air curtain. It was found that this phenomenon was due to an alleviative effect of the collision of rotating particles near the spray air outlet, so the new outermost air line of the three-fluid nozzle spray gun is used to create an air curtain. The air curtain enabled an increase of the spraying area to the maximum, and caused the spraying speed to be slower. This resulted in the reduction of cracking and abrasion of granules, and adhesion on the spray gun was prevented.
