Quantitative evaluation of kneading and extrusion processes by pressure transmission characteristics of wet kneaded masses

This study is devoted to the quantitative evaluation of wet kneaded masses prepared by a paddle-type kneader, and the analysis of the kneading process and the following extrusion granulation process. A compaction tester of wet kneaded masses has been developed and the compression properties of the masses are characterized by a pressure transmission between the upper and lower punches of the tester. The dispersion condition of a binder liquid among the wet kneaded masses prepared under various kneading times is investigated. The extrusion pressure through a single ejection hole on the lower punch is also measured. The pressure transmission is found to have a linear relationship between the dispersion of binder liquid and the extrusion pressure. This results lead to a conclusion that the proposed method provides the generalized measuring means of wet kneaded masses. An extrusion granulation by a dome-type extruder is conducted using wet kneaded masses and physical properties of the extruded pellets (granules), such as friability, specific surface area and disintegration time, are investigated. Good linearity can be found between the pressure transmission and the physical properties of the pellets. As the result of these findings, the kneading condition, i.e. the dispersion of binder liquid among the wet kneaded masses, can be quantitatively analyzed and the physical properties of pellets prepared by extrusion granulation can be accurately predicted by the pressure transmission measured by the newly developed compression tester.