Recovery of thermoplastic scrap - comprises using disc-kneader close connected to granulating extruder for increased output and efficiency and reduced thermal degradation

摘要

Process and arrangement for prepg. thermoplastics scrap to a re-usable granulate. Previously size-reduced material is fed to a disc-kneader which by kneading heats it to the softening range and delivers it radially directly to the inlet of an extruder fitted with a granulator. The outlet of the disc-kneader may be directly flanged to the extruder feed inlet. The disc kneader may be fed by a co-axial screw conveyor. The disc kneader may be preceded by a coarse size reduction and/or washing/drying device for highly contaminated feed material. USE/ADVANTAGE - Used for reclaimation of thermoplastics scrap, e.g. film, fibre, foam, powder. Increases throughput w.r.t. size of disc-kneader, since extruder completes densification. Increases process efficiency and reduces recycling energy consumption by preheating extruder feed. Processes of post-cooling, post-granulation, sepn. of fines and fines recycling no longer required. Coarser prior size redn. possible w.r.t size of kneader. Thermal degradation of the material is reduced compared with the recycling extruder.