Chemical Recycling of Polycarbonate Reaches Major Milestone

Materials supplier Covestro has developed an innovative chemical recycling process to convert polycarbonate back to its monomers so that they can be fed into the production process as alternative raw materials. Technical implementation of chemical recycling is now beginning on a pilot scale at the company’s site in Leverkusen, Germany. The process will be further optimized toward eventual deployment at a commercial scale.

"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 [that] we know how our products are designed and, therefore, can conduct targeted research into recycling solutions," said Dr. Thorsten Dreier, Covestro's chief technology officer. "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."

From mechanical to chemical recycling

Mechanical recycling of polycarbonate is already an important component 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 complements mechanical recycling in that larger waste streams that are unsuitable for the mechanical process can be treated to enable the production of plastics that meet the highest quality requirements. Covestro is actively developing chemical recycling.

Chemolysis process adapted to polycarbonate

The newly developed process, which was driven by an international team, is a specific chemolysis process adapted to polycarbonate. "Pre-sorted waste streams containing a product content of more than 50% polycarbonate can be recycled this way. This has been successfully demonstrated with various polycarbonate-containing plastic waste streams," explained Markus Dugal, head of process technology at Covestro. "With the help of chemolysis, the cycle can be closed to a direct precursor of polycarbonate. This makes the recycling process very sustainable."

The recycled product can be mass-balanced and reused as a raw material for the production of polycarbonate without further processing. "Such high-quality recycled raw materials are needed for applications that require the highest quality level. 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," said Lily Wang, head of the Engineering Plastics business entity.

Covestro is also driving forward further processes for innovative 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.