Physical blowing agent feed system into plastic comprises channels cut into mating faces of annular segments of an adaptor for an injection molding or extrusion machine

摘要

The adaptor is located between a plasticizing unit and a nozzle of an injection molder or extruder. Channels(3,6) for feeding blowing agent into polymer are formed by cut-outs on at least one of the mating surfaces(2) of an annular segment(10) and a surface of an adjacent (10) or sealing segment(11). Channels of each (10) have a tightly limited diameter variation at the opening into the plastic flow. The adaptor is located between a conventional plasticizing unit and a nozzle of an injection molding or extrusion machine. Channels(3,6) for feeding gaseous physical blowing agent into a polymer are formed by cut-outs on at least one of the mating surfaces(2) of an annular segment(10) and a boundary surface of an adjacent annular segment or sealing segment(11). Channels of each individual annular segment have a tightly limited diameter variation at the opening into the flowing plastic(4).For each annular segment(10) the diameter of the gas feed channels at the plastic side opening deviates by not 60% from a mean value. The number of channels(6) per segment on one and/or both mating faces is 10-1000. Channel diameter and shape are such that liquid plastic is prevented from entering them. Mean diameter at the outlet into the plastic is 1-50 Microm. Channels have a round, triangular, square or semi-circular cross-section. Gas is fed to the channels(6) via a ring channel(3) inside and/or outside the adaptor. There are 2-20 annular segments and 1-21 sealing units. When several annular segments form a row at least one may have a different channel number or channel diameter. One or more static mixers may be connected to the gas feed adaptor.