For 4 years, the European project known as PUReSmart researched ways to transform the currently highly linear lifecycle of polyurethane products into a more circular model. The project, supported by € 6 million in funding from the European Union Horizon 2020 Research and Innovation Programme, launched on 1 January 2019 with nine partners from six different countries for a duration of four years. Comprises both industrial players and dedicated research partners, the consortium represents the entire polyurethane reprocessing value chain.
Thermoset PU products such as flexible and rigid foams are long-lasting and durable and are among the six most important plastic materials produced worldwide. However, compared with thermoplastic materials, recycling thermoset PU is a much more challenging process.
Now completed, the project yielded a positive outcome - at least in the view of consortium member Covestro and leading company Recticel - as it proved possible to demonstrate that the two main raw materials originally used in flexible polyurethane (PU) foam from mattresses could be chemically recovered. The quality and purity of the recovered polyol and toluene diisocyanate (TDI) were extremely high, enabling the production, for the first time, of a flexible foam sample made from fully recycled raw materials. Both raw materials - the polyol and the TDI - were obtained through tests at Covestro’s pilot plant in Leverkusen.
These results were achieved through a chemolytic process requiring only pre-sorted foam from mattress waste, a glycol and an additive. During chemolysis, the polyol and toluene diamine (TDA), the precursor to TDI, that, after reprocessing, can be used again as often as required for the production of new PU flexible foams.
"For the first time in history, polyurethane is truly fitting into a circular economy,” said Bart Haelterman, R&D Director at Recticel.
Covestro is now working to take the results of the PUReSmart project, to the next level. To that end, the company is collaborating with partners from the waste management industry, aiming to push flexible foam recycling through to industrial use.
The goal is to turn waste into valuable raw materials and to ‘anchor the principle of the circular economy in the company’, said Christine Mendoza-Frohn, head of performance materials sales EMEA & LATAM at Covestro.
“We call this ongoing Evolution of Recycling: Evocycle CQ. The first initiative of this kind is dedicated to the chemolysis of PU mattress foam and is called 'Evocycle®CQ Mattress’."
This enables end-of-life mattress foam to be transformed directly back into its main building blocks. In this way, Covestro aims to close the loop in the PU mattress industry, reducing the use of fossil fuels and significantly lowering CO2 emissions. However, there are still many steps to be taken before this vision becomes reality, especially with regard to upscaling the process.
Covestro will continue to conduct trials at the pilot plant at its Leverkusen site, which it built in 2021, to verify the positive laboratory results achieved to date. If the trials continue to be successful, the company plans to build a larger recycling plant to validate the technology in an industrial simulation environment.
For an effective, viable closed-loop system, however, a consistent and cost-efficient supply of used PU mattresses must be secured. In other words, large quantities must be collected, broken down into individual components such as springs, textiles and foam parts, and the foam components pre-sorted according to purity and density. This can only succeed in close cooperation with partners – in this case in the recycling industry. Covestro is already cooperating on this with companies such as Interzero and Ecomaison -formerly Eco-mobilier.