In the process, plastics are converted back into their monomers so that they can be fed back into the production process as alternative raw materials. At Covestro in Leverkusen, the technical implementation of chemical recycling is now beginning on a pilot scale.
Dr. Thorsten Dreier, Covestro's chief technology officer, said: "As a manufacturer of plastics such as polycarbonate, we naturally have a responsibility in dealing with these important materials, including at the end of their product life. Our advantage is: we know how our products are designed and can therefore conduct targeted research into recycling solutions. The chemical recycling of polycarbonate is another example with which our colleagues in development show that closed cycles are possible in the future. We need to use end-of-life plastics as a resource and reuse them as alternative raw materials to close the loop."
The return of plastics through recycling replaces primary fossil raw materials in production. Comprehensive recycling thus contributes to climate neutrality and the protection of natural resources and the environment. Mechanical recycling of polycarbonate is already part of Covestro's recycling strategy. The mechanical recycling process is used whenever waste streams are sufficiently pure and the recycled polycarbonate meets the requirements profile of the future application.
Chemical recycling works in a complementary way to mechanical recycling - it converts plastic building blocks back into their individual building blocks. These can be separated and serve as raw materials for future plastic.
According to Covestro, chemical recycling can therefore make larger waste streams that are unsuitable for mechanical processes in particular accessible for recycling.
Covestro’s new method is a specific chemolysis process adapted to polycarbonate.
Markus Dugal, head of process technology at Covestro, said: "Pre-sorted waste streams containing a product content of more than 50 percent polycarbonate can be recycled this way. This has been successfully demonstrated with various polycarbonate-containing plastic waste streams. With the help of this chemolysis, the cycle can be closed to a direct precursor of polycarbonate. This makes the recycling process very sustainable."
The recycled product, a precursor of polycarbonate, can be mass-balanced and reused as a raw material for the production of polycarbonate without further processing.
Lily Wang, head of the engineering plastics business entity, said: "Such high-quality recycled raw materials are needed for applications that require top quality. These include for example, applications in the automotive sector with special requirements in terms of safety, optical transparency or aesthetics, and products in our everyday lives such as consumer electronics.”
The pilot plant will be used to gather the experience needed for further expansion to industrial scale. At the same time, Covestro is driving forward further processes for recycling of polycarbonate in its research laboratories. These include chemolytic alternatives, recycling with enzymes that break down the plastic, and smart pyrolysis. Promising alternatives can also be tested with the pilot plant.
