Posted on 15/10/2019 in Recycling 2019
Recycling flame retardant plastics

Jürgen Troitzsch, Fire and Environmental Protection Services, summarised the opportunities for the circular economy for plastics and implications for flame retardants. World demand for polymers is continuing to grow exponentially, but also to grow more slowly in Europe. On the other hand, only just over 1/5 of Europe’s total material needs are met by recycling. However, a range of EU regulations are pushing to improve recycling: the Waste Framework Directive (with obligations for increasing waste collection and recycling), landfill, packaging, end-of-life vehicle, batteries legislations, and WEEE (Waste Electrical and Electronic Equipment) Directive. Plastics can be valorised by mechanical recycling, chemical processing back to feedstock, energy or use in energy production. A number of FR/polymer combinations have been shown to be compatible with mechanical recycling, but POPs restrictions, REACH SVHC classifications and RoHS prevent this for plastics containing certain brominated FRs (PBDEs, HBCD, with discussions underway on antimony trioxide, TBBPA, chlorinated paraffins and chlorinated phosphate esters) and RoHS requires removal of any plastic containing brominated FRs. Chemical recycling will be possible for plastics containing these problematic FRs.

Lein Tange, ICL, considers that the actual challenge is that mechanical recycling of plastics is only possible if end-of-life plastics are collected and precisely sorted, in order to generate secondary streams of consistent and compatible materials without hazardous impurities. Recycling is only feasible if such sorted input streams are represent industrially significant quantities. Additionally the price of plastic articles alone does not today cover the end-of-life costs (collection + sorting + recycling). He presented the CreaSolv® Process developed by Fraunhofer IVV and the Polystyrene Loop Cooperative (PSLoop), with the aim of physical purification of end-of-life polystyrene containing “legacy” brominated FRs (HBCD) back to purified polystyrene polymer and recovery of bromine. A demonstration plant of 3 000 t/year is now planned (cost over 10 M€). Other processes at development scale work are super heated solvent recycling of HIPS and ABS in thePLAST2bCLEANED project and the CreaSolv® Process in the CLOSEWEEE project (both EU funded).

Elke Metzsch-Zillingen, Fraunhofer LBF, Darmstadt, Germany, presented results of tests of mechanical recycling of PIN flame retardant polymers, funded by pinfa. Tests covered widely used polymer / FR combinations, with polypropylene, polyethylene, polyamides and polycarbonate, and PIN FRs: APP, pyrophosphate, ATH, DEPAL, melamine cyanate, non-halogenated phosphate ester. For 9 out of 10 combinations, after multiple re-extrusions, and after accelerated ageing, flame retardancy was retained, but for many combinations, material properties deteriorated – but this is considered to be mainly related to impacts on the polymer and on glass fibres, not related to the PIN FR. The overall conclusion is that mechanical recycling for widely used polymer / PIN FR combinations is possible, subject to careful reformulation with appropriate additives to correct polymer deterioration and use of appropriate extrusion equipment. An important comment is that the prerequisite for mechanical recycling is that collection and sorting systems for end-of-life plastics must be in place and effective.

Share This