Injection molding screw for microcellular process for polymer materials, comprises pressure retention element to be positioned between first stage portion and second stage portion for reducing loss of pressure in the second stage portion

摘要

An injection molding screw comprises first end, second end, longitudinal body, and pressure retention element. The first stage portion is adapted for first receiving at least one substance and for transporting the at least one substance to the second stage portion. The pressure retention element adapted for being positioned between the first stage portion and the second stage portion for reducing loss of pressure in the second stage portion. An injection molding screw (10) comprises first end, second end, longitudinal body, and pressure retention element. The first end is adapted for engagement with drive end (12). The second end is adapted for engagement with a screw tip (54). The longitudinal body extends axially along a length of the screw between the first end and the second end. The body comprises a first stage portion (20) and a second stage portion (22). The first stage portion is adapted for first receiving at least one substance and for transporting the at least one substance to the second stage portion. The first stage portion includes flight(s) extending helically along the first stage portion. The flight(s) form at least one channel (56) through which the at least one substance is transported along the first stage portion to the second stage portion. The second stage portion includes mixing section, and being adapted for transporting the at least one substance transported from the first stage portion to the screw tip. The mixing section mixes the at least one substance transported from the first stage portion and for transporting the at least one substance that has been mixed to the screw tip for extrusion where the at least one substance transported from the first stage portion at least one fluid is introduced to by at least one injection port of a processing system. The pressure retention element adapted for being positioned between the first stage portion and the second stage portion for reducing loss of pressure in the second stage portion.