Plastic circularity for difficult-to-recycle packaging materials continues to progress. In the latest development, Solvay and Carbios have successfully demonstrated that multilayer PET ﬁlms coated with Solvay’s Diofan-brand polyvinylidene chloride (PVDC) high-barrier polymer are fully compatible for enzymatic depolymerization using Carbios’ innovative recycling process. Results show that the PET is fully depolymerized, whereas the PVDC remains intact.
Carbios is the ﬁrst company to develop 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 that conﬁrmed that waste from packaging or other applications using bi-oriented PVDC multilayer ﬁlm can be efﬁciently recycled without compromising the high 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.
Brands and other companies 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 in food packaging where it delivers impressive barrier properties, these multilayer structures have been challenged regarding 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, Carbios. “Conventional thermo-mechanical routes require clean monomaterial-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 in food packaging applications ranging from fresh and processed meat to ﬁsh, poultry and cheese. The polymers provide a superior barrier against water vapor and oxygen as well as odors and loss of aroma or ﬂavor.