APPARATUS AND PROCESS FOR THE UNDERWATER PELLETIZATION OF POLYMERS

摘要

Underwater melt pelletizer dies which have a highly thermally conductive pathway from their heating source to the vicinity of the polymer exit end of their die holes and have a thermally insulating material at that end of their die holes have improved operability and can pelletize thermoplastics which are otherwise difficult or impossible to pelletize with such an apparatus. The main construction members of such a die are a relatively high strength but relatively low thermal conductivity plate (21), a second plate having a relatively low strength but relatively high thermal conductivity (22), a coller (23) (which is usually of relatively high strength but need not have a high thermal conductivity) to help hold the assembly together, and relatively strong mounting hole liners (24). These parts of the die may be joined by "temporary" mechanical means such as bolts (not shown), but are preferably permanently joined together by welding and/or brazing, shown by regions (25) and (26). For example, (21) and (23) may be steel or stainless steel, and may be joined by welding. Then (22), which may be copper or a copper or aluminium alloy, may be brazed to both (21) and (23).