Single screw extruder - having spaced discontinuous helical flights each centered between preceding flights

摘要

Extruder screw has a succession of individual spaced offset discontinuous helical flights, each successive flight being centred between preceeding flights, the flights having the narrowest width-channel between flights within the range from -0.25 to 3 diameters of the screw. The screw has the following advantages over prior art. mixing devices and extruders pumping capacity, relatively low pressure drop, relatively low processing temperatures exponential stream splitting, independence of steam velocity, viscosity or density, and low shear back mixing where reverse pitched flights are used. The screw can be used for piller compounding of solid polyolefins, blending of different polyolefins, and reacting of monomers with polyolefins such as in extruder grafting.