Despite several studies on PA/PE films, recycling guidelines of various organizations still classify polyamide (PA)-containing packaging as non-recyclable. The independent institute “Cyclos-HTP”, along with “BASF”, have conducted further extensive research into recyclability of multilayer films that contain polyamide 6 (PA6) and ethyl vinyl alcohol (EVOH) copolymer, with promising results in a standard polyethylene (PE) stream.
Previous Research Findings
In 2022, “BASF” and “Cyclos-HTP” released a publication detailing the mechanical recycling of coextruded flexible packaging films containing polyamides. The recyclability of PA/PE coextruded, multilayer films was systematically investigated and confirmed by “Cyclos-HTP” in June 2021, while for the conducted tests, PA/PE multilayer films with concentrations of up to 30 percent PA6 and PA6/6.6, with tie layer materials, were used.
The compatibility and recyclability of these films were tested based on the established CHI standard. These updated results were then used for the differentiated certification of recyclability of individual flexible PA/PE packaging structures.
New Investigation on the Recyclability of Polyamide Films
“Cyclos-HTP” continues the extensive research, this time deepening into recyclability of films containing polyamide 6 (PA6) and ethyl vinyl alcohol (EVOH) copolymer.
“BASF” commissioned these research studies to also include coextruded PE/PA6/EVOH high-barrier films and laminated OPA-PE films found in household packaging waste. When it comes to laminated structures, an additional compatibilizer is introduced, which plays a vital role in evenly distributing the Polyamide (PA) component in the Polyethylene (PE) matrix.
The Investigation Results
Dr. Matthias Zorn, Senior Manager of Market Development Polyamides for extrusion applications at “BASF”, clarifies that “the results show that PE film waste streams containing PA can be processed without significant adjustments to the recycling process”. He goes on to explain that “the certification confirms the standard market practice of PA-containing film waste already being recycled by film manufacturers today”.
During the recycling process of coextruded structures, the already existing tie layer used to bond PA and PE in the film, a laminating adhesive from Henkel for this particular study, becomes an effective compatibilizer. Moreover, Zorn states that by adding more functionalized Polyethylene (PE-g-MAH) as a compatibilizer during primary film production, the polyamide is acknowledged by “cyclos-HTP” as a valuable material in polyethylene recycling.
Recycling Compatibility of Adhesive-Laminated OPA-PE Films
While PE/PA/EVOH films are ideally used for food packaging, laminated structures are mainly found in printed film packaging for various industries, including food. The study on adhesive-laminated OPA-PE films, which was performed by “BASF” in cooperation with “SÜDPACK”, clearly indicated how these previously considered non-recyclable films, can in fact be converted to become recycling-compatible.
According to these results, a broad range of PA-containing packaging can now be certified as recycling compatible, due to the unique properties of polyamides. As it is common knowledge in the packaging industry, polyamide reduces the amount of required material used for packaging and thus assists in overall reduction of packaging waste pollution, while also improving the mechanical, thermal and processing properties of packaging.
Germany’s Acknowledgement of Coextruded PA/PE film Recyclability
Results of this study were shared with the “Central Agency Packaging Register”, which establishes the annual German minimum standard for assessing recyclability, and last year implemented the recyclability of coextruded PA/PE films in “German minimum standard” for determining the recyclability of packaging.
Conclusion
Following the aforementioned series of investigations that were conducted, it was confirmed that multilayer films containing polyamide 6 (PA6) and ethyl vinyl alcohol (EVOH), along with laminated OPA-PE films, can be effectively recycled in the polyethylene film stream. This outcome was also shared with the CEN standardization group, which is responsible for developing a “Design for Recycling” directive on a European scale, and thus, recognition of recyclability of coextruded PA/PE films is expected to be implemented in more European countries in the years to come.
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