Extruder and process modifying residence time distribution

摘要

Modifying the mean residence time and the residence time distribution of materials in a reaction or mixing zone of an extruder having an inlet, a discharge outlet and twin non-intermeshing counter-rotating screws which are parallel or tangential to one another and have the same directional pitch, comprises:- (a) restricting the flow of material from the reaction or mixing zone toward the outlet and toward the inlet, (b) moving material along one of the screws in a direction from an area near the outlet toward the inlet, (c) transferring material to the second screw, and (d) discharging material from the reaction or mixing zone through the discharge outlet.