(493h) Impact of Foam Quality On Granule Quality Attributes

High shear wet granulation is a common process for forming agglomerates. Water addition rate and distribution method can sometimes have effects on the granulation. For some materials distribution of water can be essential to achieving a homogeneous granulation with desirable properties. A new granulation process has been developed by the Dow chemical company, whereby liquid binders are added as aqueous foam. Experiments indicate that foam granulations require less water than spray granulations, rates of addition of foam can be greater than rates of addition of sprayed liquids, and foam can even be added in a single portion to the granulator. In addition, the foam granulation process eliminates the need to consider selection of spray nozzle(s), characterization of the spray from nozzle(s), distance from the nozzle(s) to powder bed, and the location of nozzle(s) in the granulator.

The quality of foam (given as the ratio of air to liquid on volume basis present in the foam) might impact the quality of granule attributes. To investigate this, two placebo batches were manufactured at 80% and 90% foam qualities. The quality of the foam was monitored in real time using the Turbiscan Lab instrument. The Turbiscan Lab works on the principle of light backscattering to quantify the kinetics of foam breaking. A backscattering plot obtained at each condition was used to finger print the quality of the foam at the given flow rate. A new on-line instrument was used to carry out the analysis.

Granule characterization results indicate that a batch made with foam of 80% quality produced smaller and softer granules compared to a batch made with 90% foam quality. Yield pressure is less for granules manufactured with 80% foam quality, indicating that they have more compressibility. These results were supported by the mercury intrusion porosimetry results, which show that granules manufactured with 80% foam quality were more porous compared to those made with 90% foam quality. Results confirm that foam quality is an important process parameter that should be monitored during the granulation process as it has an effect on the quality attributes of the granules.

Key Words: Foam Granulation, Granules Characterization, Porosity, Foam Quality, Turbiscan Lab instrument.