NGR Develops Effective Solution for Bioplastic Recycling
Most plastic application generate scrap and waste in one form or another. Next Generation Recyclingmaschinen GmbH has taken advantage of the growing use of bioplastics. Production waste can be melt lumps, sprues and defective parts in injection moulding, parison waste in blow moulding or for example edge trim, cutoffs and off-spec startup material in film and fibre production processes.
NGR has suggested that its new technology can only gain importance for bioplastics, which often cost as much as €3 per kilogram or even more.
The easiest way of recovering these materials is to shred them to chips and re-feed them into the process together with the new material, but as easy as that is, it can lead to process difficulties like:
• Inconsistent feeding performance of the production extruder
• Air inclusions in the melt that lead to defects of the finished products
• No way of removing process materials like printing inks and similar
NGR’s solution involves recycling machines that feed the material to the extruder with an integrated cutter-feeder, which consists of a slow rotating cutter shaft with knives that cut against fixed knives like scissors, and a feeding zone that conveys the material to the extruder without pre-heating it.
The NGR Cutter-Feeder-Extruder can reportedly recycle most of the commonly used bioplastics, such as starch or PLA-based products. The screws, vacuum vent and melt filter can all be tailored to the special requirements of bioplastics, for example low heating of the material or the removing of printing inks.
This method is also sensitive towards monitoring slight changes in the molecular mass distribution resulting from the inevitable heat stress in any polymer processing step.