Browsing by Subject "dry powder coating"

The goal of the thesis was to optimize a dry powder layering process that would produce a swelling polymer layer that could work as a base layer for another layer. The GPCG 1 (Glatt) fluidized bed granulator was equipped with a rotor. Such hydrophilic polymers were used for coating that would not be sensible timewise for wet coating methods because of long process time. For design of experiments Definitive Screening was chosen because it works in situations where time is limited and there is high number of parameters. There were six parameters, four related to the equipment settings and two related to the formulation, that were tested on three levels. The results were used to get optimized parameters using a model in MODDE software. The quality of the coating was analyzed by measuring the friability (strain test with fluidized bed granulator), particle size (dynamic image analyzer), density (helium pycnometer and mercurity porosimeter), erosion (size exclusion chromatography), loss on drying (halogen moisture analyzer) and coating efficiency (weighing and loss on drying). Coating was also analyzed also with scanning electron microscopy. The process was robust with regards to sphericity of the coated pellets. In SEM pictures none of the coatings showed complete film formation. Friability method did not show significant differences between batches. Coating efficiency was high for all batches. Correlations between product characteristics were analyzed and some correlations were observed between including correlations between LOD/CE and densities. No correlation between the densities measured with two different methods were seen. Some of the settings in the DOE were too extreme and produced batches that were very difficult to analyze. Two more batches were produced with adjusted settings. This affected somewhat the ability to develop a reliable model. Model development were also affected by insufficient results from erosion tests and because coating efficiency results with water was used. Some stability problems were noticed during design of experiments and chosen equipment limited the scale of settings. Coating material adhered to the surface of the pellets and process could be adjusted by changing the parameters of the DOE. Some correlations were noticed between formulation, equipment settings and coating properties.