When used with a polypropylene cap, the new ProTecSeals polypropylene (PP) foam closure liner from Tri-Seal, a business unit of Tekni-Plex, creates a mono-material closure that is suitable for a variety of products, including personal care items, cosmetics, home care products, pharmaceuticals/nutraceuticals, and foods like sauces and spreads.

Available in the US and Europe, the liner helps brand owners meet the European Union’s 2030 target for recyclable plastic packaging — and without leaving consumers the inconvenient task of separating packaging materials before recycling.

An independent third-party lab has verified that correctly calibrated near infrared (NIR) systems at municipal recycling facilities (MRFs) can identify the ProTecSeals and sort polypropylene closures with this liner into the #5 recycle stream.

According to Guangda Shi, senior director of global technology for Tekni-Plex, a new technical development in the foam formulation and foam process has allowed the company to develop this all-polypropylene liner that can be identified by an NIR scanner as PP. The company’s previous all-PP liner focused on density reduction and heat resistance to serve as a secondary backing line (that is, placed behind an induction liner). The company can also make expanded polyethylene (EPE) and expanded polypropylene (EPP) monolayer liners, in addition to coextruded liners.

This new liner joins others already in the ProTecSeals product line. Earlier ProTecSeals products launched in January 2020 — specifically F-224, F-419L and F-830 — touted post-consumer recycled content. These new NIR-identified ProTecSeals liners do not contain PCR at this time due to regulatory requirements from the customers and performance needs of the applications.

However, the new NIR-identified liner does help minimize the amount of plastic. Shi explains, “Our process optimization effort in 2019 and 2020 provided capability for us to process ‘difficult to foam’ PP resins/formulations and achieved similar unit weight ranges as compared to the PE foam liners.”

Shi addresses other questions about recycling: How does this PP foam liner adhere to its closure? If there is an adhesive, does it interfere with recycling? “The majority of the applications use mechanical means — friction fit — or closure design with recess to retain the liner. When glue is used, the weight is limited to the APR [The Association of Plastics Recyclers] guideline and controlled by our customers.”