Recycling
PIN flame retardants can be compatible with polymer recycling.
Mechanical recycling
Re-using the plastics as such after separation and sorting, grinding, dosing of polymer restoration additives, then reprocessing (injection moulding, extrusion …) into new products.
Feedstock recycling
Breakdown of the plastics into their chemical constituents which can then be used to manufacture new plastics or other materials.
Energy recovery
Capturing the energy content of plastics, usually by combustion with energy generation (electricity, heat, steam).
Flame retardants are designed to durably provide fire safety throughout products’ lifetimes, which can be decades for construction materials. They should also be compatible with safe recycling at the end of this lifetime.
This durability of PIN flame retardants enables their compatibility with recycling (re-blending, re-processing).
PIN flame retardants (not containing halogens) aim to be compatible with safe recycling decades in the future, by offering both durability over time and chemical safety. PIN flame retardants offer the inherent advantage of not contributing to possible dioxin emissions in case of inappropriate disposal.
PIN flame retardants and mechanical recycling
Tests carried out by Fraunhofer LBF for pinfa of multiple-cycle recycling of ten widely-used polymer – PIN FR compounds showed that fire performance was generally retained, and that deteriorations in mechanical properties or fire performance were generally related to damage to the polymer, to glass fibres or to anti-drip additives in recycling, and not related to the PIN FR.
This confirms results from other published studies.
Compounds tested and processing conditions
In all cases, compounds also included standard commercial stabiliser and/or anti-drip additives at 0.1 – 0.3%. LLDPE included a coupling agent at 5%
PIN flame retardants can be produced using recycled (secondary) raw materials
Full-scale pilot industry tests have demonstrated that phosphorus can be recovered from sewage sludge or other ashes, and used as a raw material for industry, including PIN flame retardants production (see)
Magnesium industry by-products can be used as input to mineral PIN flame retardant production (eg. “Recovery of Magnesium from Waste Effluent in Nickel Laterite Hydrometallurgy Process”, Sun et al., 2012 – link)
Some PIN flame retardants can be recovered as such during polymer recycling, e.g. “Recovery of triphenyl phosphate from waste printed circuit boards by solvothermal process, Zhang et el., 2013 – link)
Raw materials used in PIN flame retardants can be recovered
it is possible to recover some of the basic chemicals used in PIN flame retardants (phosphorus, minerals) in processes where waste polymers are treated (e.g. metal smelters used to recover copper and rare earths from electronic wastes, incinerators producing energy from waste plastics), although this is not to date operational.
PIN FRs and fire safety of recycled materials
PIN flame retardants are the first-choice, for sustainability reasons, for fire safety in recycled plastics and polymers, and in other recycled materials such as recycled textiles or fibres for insulation.
