Process design in continuous melt granulation

Within a pharmaceutical production line for tablets as main oral solid dosage form, granulation is typically applied to modify the handling and dosing properties of bulk materials a priori the direct compression step. Thereby, research endeavors over the last decade shifted from batch to continuous manufacturing, which applies in general for pharmaceutical technology. Further, the melt granulation was focused as this method complies with sustainability objectives since a subsequent, energy intensive drying step is not required and the resource water is not consumed during processing. The handling of moisture sensitive materials is also feasible. In comparison to the application of twin screw systems as a gold standard for continuous melt granulation up to date, the use of a planetary roller system has been introduced lately as promising alternative [1]. Benefits refer to the unique process concept (Figure 1). This features an enhanced ratio of heated surface to processed volume, while the machine fill level [2] is linked to the transport and energy input mechanisms. Therefore, direct process parameters (feed rate and rotation speed) are correlated to the particle size as main quality attribute of the product. In this study, the main objective is the module configuration as one central process design element of planetary roller melt granulation. This includes the number and type of planetary spindles and is the equivalent to the screw configuration for twin-screw processes, which refers to the sequence of applied screw elements. Thereby, the experimental investigations deal with the impact of the configuration on the material transport reflected by the residence time distribution and the granulation performance indicated by the particle size distribution.