Application of the core-shell-type granulation process for the preparation of compression molding granules containing fibrous material and powders

Acore-shell granulation process has been investigated using a bottom agitaton-type mixer in order to control the segregation of fine powders and improve the flowability of irregular-shaped composite granules containing fibrous materials. Following the mixing of powdery components (matrix and thermosetting resin) with the fiber, the mixture was granulated so as to obtain a relatively napped granule (core) surface. The optimum operating conditions for the formation of the soft powder layer (shell) onto the core granules without damaging the napped fibers is discussed on the basis of changes in the physical properties of the granules and the mechanical strength of the sintered test pieces. The experimental results show the effectiveness of the formation of a network among granules during the molding operation using the proposed granulation process.