Enzymatic Depolymerization in PET/PVDC Barrier Film

Solvay and Carbios successfully demonstrated that multi-layer PET[1] films coated with Diofan® PVDC[2] high-barrier polymer are fully compatible for enzymatic depolymerization - Carbios’ innovative recycling process. Results show that the PET is fully depolymerized, whereas the PVDC remains intact. Carbios is the first company to have developed enzymatic processes dedicated to the end-of-life of plastics and fibers. The collaboration builds upon the results of an earlier proof of concept by Solvay which has confirmed that waste from packaging or other applications using bi-oriented PVDC multi-layer film can efficiently be recycled without compromising the outstanding barrier performance of the polymer. It aligns with Solvay One Planet's sustainability ambition to preserve resources and contribute to safer, cleaner and more sustainable products. “OEMs and brand owners are under tremendous pressure to increase the sustainability of their products,” says Guruprasad Sivakumar, Head of Marketing for Consumer, Healthcare and Environment at Solvay. “While PVDC has long been used for coating flexible PET films e.g. in food packaging, where it delivers impressive barrier properties, these multi-layer structures have been challenged regarding their recyclability. This is where Carbios’ unique recycling technology comes as a real game changer. By providing a feasible and sustainable end-of-life management solution, it can help the industry close the loop on PVDC-coated PET films and extend the value proposition of our high-barrier specialty polymers to further markets, such as the packaging of pharmaceutical products.” The patented recycling process developed by Carbios works with specific enzymes to break down the PET molecules back into their constituent monomers. The technology uses moderate temperatures, which is ideal in the presence of PVDC, and can be applied to recycle post-industrial as well as post-consumer waste. The resulting monomers could be purified for reuse in the production of a new PET polymer of the same quality as those derived from virgin petrochemical feedstock. Notably, the joint study by Solvay and Carbios has demonstrated that PVDC does not jeopardize the depolymerization of PET. “Our enzymatic approach overcomes the limitations of other recycling processes,” explains Alain Marty, Chief Scientific Officer at Carbios. “Conventional thermo-mechanical routes require clean-mono-material grade waste, and high-heat chemical or pyrolytic recycling cannot be used to regain the material value still present in many end-of-life applications. As the industry’s first solution for the recycling of complex multi-layer structures such as PVDC coated PET films, our enzymatic biological recycling makes a significant contribution to help the plastics economy become more circular. The joint study with Solvay also shows what can be achieved by collaborating towards a common goal – to the benefit of all players along the value chain.” Solvay’s Diofan® and Ixan® high-barrier polymers have a track record of proven food packaging applications from fresh and processed meat to fish, poultry and cheese. They provide a superior barrier against the permeation of both water vapor and oxygen – most existing alternatives only meet one or the other purpose – as well as to odors and loss of aroma or flavor. Diofan® and Ixan® are registered trademarks of Solvay.