Producing mouldings from plastic scrap - by fusing in homogenising extruder, discharging continuously into base of vessel fitted with plunger, injecting in cycles into cold mould

摘要

Moulding is produced from mixed plastic scrap by fusing the material in an extruder, feeding it into a suitably shaped mould, cooling, and demoulding. From the extruder the melt is first passed into an intermediate chamber before then being injected in cycles into the mould. Disintegrated plastic scrap of any kind, but with sufficient thermoplastic content to ensure that it can soften under heat to a paste, is fed into a 200-600 kg/hr capacity extruder. The fused mixt. discharged from the extruder is fed continuously into an intermediate container fitted with a spring-loaded top plunger. As the mix is fed into the container the plunger rotates, moves upwards and homogenises the mix. When the container is full the plunger descends rapidly and injects the shot into the mould cavity. The mould can contain e.g. a steel mesh, which is fully encapsulated by the shot; the resultant prod. then having reduced creep properties. ADVANTAGE - It is possible to produce larger mouldings from the scrap than has higherto been possible. It can produce them up to the size of telegraph poles