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PolyUrethane Recycling towards a Smart Circular Economy

Periodic Reporting for period 1 - PUReSmart (PolyUrethane Recycling towards a Smart Circular Economy)

Reporting period: 2019-01-01 to 2020-06-30

In contrast to thermoplastic polymer materials (plastics), recycling of thermosetting PU is not possible by heating and reprocessing in a liquid form. Some recycling solutions exist (mechanical recycling, alcoholysis, acidolysis…), but they poorly address the issue of the huge waste streams generated by the disposal of end-of-life products brought by the fast-growing PU industry (small markets, chemical intensive process…). As a result, 45% of the end-of-life (EoL) PU is landfilled, while 33% is incinerated. This dramatically impairs the environmental sustainability of PU. The European Union has set ambitious targets with the goal to reuse and recycle 55 % of the municipal waste in 2025 and to reduce landfill of municipal waste to max 10 % by 2030.
The ambition of the PUReSmart project is to develop new concepts to reshape the value chain into a closed loop.
Primarily, the consortium focuses on the development of a new PU chemistry, enabling a PU with thermoset properties under its life conditions to be recycled when applying different conditions. PUReSmart will develop Covalently Adaptable Polyurethanes (CAPU’s) based on click chemistries, fast reversible chemistries that enable the creation of cross-linked polymer networks reversible under certain conditions. Three different routes are under exploration. The choice of best candidates will be determined by their technical and economical feasibility.
Along this line, the consortium aims to develop a new reprocessing technology targeting to recycle polymer foams back to foams. The objective is to find a new PU based chemistry and a recycling process enabling full recyclability. PUReSmart also aims at treating current PU materials. As a first step, the partners work on the sorting of EoL PU based materials in order to recover the raw materials (or their precursors) that have been used to produce these products. Indeed, detection and sorting is known for a number of thermoplastics (PET, PE...) but is not yet applied on PU foams. Therefore, detection methods will be developed in order to characterize and distinguish different PU foams. Once this is possible, sorting methodologies will be put in place in order to collect the different families in the purest form possible.
In a next step, these sorted polyurethane families will be chemically broken down thanks to a chemolysis process to recover the basic raw materials. As PUare a complex network of different chemical bonds, it is of utmost importance to have an efficient breakdown enabling to separate the basic raw materials for re-use at high levels in new polyurethanes. The final aim of the PUReSmart project is to recover the raw materials from existing PU products today on the market, and to use these raw materials to make the new generation of recyclable thermoset polyurethanes.
The development of new chemistries in order to obtain CAPU’s is moving forward. From the several new TAD-based molecules synthetized by UGent, two were selected (based on two different indole structures) and are being further investigated. The compatibilization of the TAD-based comonomers and their up-scalability are now taken into account directly during the design and synthesis of the comonomers as concerted work between Covestro, Weylchem and UGent. The first CAPU elastomers were obtained at UGent and are being further evaluated. First CAPU foams were obtained at Recticel using alternative non-TAD chemistries. The targeted hardness and densities were reached, but the decision was taken not to study these two alternative non-TAD chemistries further in foam formulations because of inherent problems with both. Further work was performed at the UCLM on reprocessing methodologies for the new polymers.
The work regarding the development of innovative sorting methods moves ahead of schedule. Under the leadership of Redwave supported by Covestro and Recticel, detection methods were found to distinguish different PU foam families. As a feedback from the ‘Smart Chemolysis” work package, the foam families were reorganized to enable an economical feasible but high quality chemolysis process. In addition, the foam families were dedicated/grouped to different “sorting buckets” to allow a cost-effective but proper chemolysis. The water uptake, the fire retardancy present in the foams and the light weight of the material are among the challenges for the emphasized sorting technology that were tackled during the last months.
The chemical breakdown of current polyurethanes is mainly investigated by KU Leuven, Covestro, Recticel and the UCLM. Based on the screening of different chemolysing agents and separation methods, the most industrial feasible method was selected and now Covestro is investigating the feasibility of a short-term scale-up from laboratory scale to semi-industrial level to enable the handling of larger quantities of foams and to finally generate recycled polyol and recycled amine fraction. This will give valuable input on yield, purity, process (T, Energy, pressure) data and will enable foaming trials with the recycled products.
Ecoinnovazione improved their data for the analysis of the sustainability characteristics of the project for the baseline scenario, including investigation on market demand for recycled PU or recycled raw materials from secondary PU in light of recycling routes which will be available at 2030. They also started to gather data for the first PUReSmart concepts.
Important efforts were made regarding the communication and dissemination activities. The PUReSmart website and a LinkedIn profile, a video (https://youtu.be/ZzcJH6ExSs4) was launched that presents the objective of PUReSmart, its organization and explains the societal, environmental and financial benefits of the project. In addition, various press releases were launched by the different partners and picked up by local press in several countries. A first Newsletter was released in May 2020 to the stakeholders/advisory board of the PUReSmart project.
In several work packages, breakthrough steps are already made. This will move the whole project far beyond the state-of-the-art. This is also proven by the two patent applications submitted by Covestro and Recticel related to the smart chemolysis progress and the earlier decision of a short-term scale-up from laboratory scale to semi-industrial level for the chemical recycling process. The recuperation of polyol fractions is known and industrially applied, however it suffers from a wrong mass balance (i.e too much solvents have to be used and the recycled products can only be re-used at low percentages together with the virgin polyol stream in non-flexible foam applications). The PUReSmart project is working on a process with complete recovery of not only the polyol, but also of the isocyanate precursors (amines), which will hopefully lead to the first recycled isocyanate in the world.
In addition, partners are asked frequently by their customers, the press and the public in general about the PUReSmart project and its progress, reflecting their interest.
The impact of PUReSmart is extremely important in the treatment of End-of-Life (EoL) PU products. As today the recycling options are rather limited, the project will bring new solutions to recover valuable raw materials out of EoL materials to be re-used to make a new generation of CAPU foams. This will close the loop and create opportunities for a circular economy.