The Circular Economy & Metallized Polyester
PET film will remain in many flexible pouches for years to come; this article explains how mechanical and chemical recycling produce PCR-PET, and how metallized PCR-PET films deliver high barrier for the circular economy.
As converters and brand owners develop 100% PE film mono-webs for the How2Recycle® Store Drop-Off program, it has become clear this approach won't work for all flexible packaging structures in the short term. Most stand-up pouches and flexible pouch formats use thin gauge PET films as the print web and/or barrier web in multi-material lamination because PET film offers low cost, easy printing and metallization, high clarity, high barrier properties, and high stiffness.
The Secret Life of PET
Many flexible pouches will remain in mixed material formats containing PET film for some time. Rather than exclude these from the circular economy, they can incorporate recycled content into packaging materials. A large infrastructure already exists to produce PET chips from post-consumer recycled sources, primarily PET bottles. According to APR, approximately 5.9 billion pounds of PET bottles were sold in the US in 2017, with 29.2% collected through recycling programs and 1.6 billion pounds reprocessed into recycled PET chip (r-PET). Reclaim and recycle rates are higher globally: over 50% in the EU and over 80% in Japan.
2 Paths to Recycling: Physics or Chemistry
Mechanical Recycling
The lowest cost approach involves chopping bottle-grade r-PET resin into flake and blending it with film-grade PET resin prior to extrusion. This presents challenges: bottle-grade resin has higher intrinsic viscosity affecting processability, a whitish tinge compared to clear film-grade resin, and greater likelihood of containing gels. Manufacturers cannot exceed approximately 30% recycled content by weight before properties deteriorate.
Chemical Recycling
Higher post-consumer recycled (PCR) content requires chemically recycled r-PET resin. The PET chain undergoes glycolysis with monoethylene glycol, producing bis(2-hydroxyethyl) terephthalate (BHET). Hydrolysis then produces MEG and PTA—original PET building blocks. These monomers are re-polymerized into "new" resin virtually indistinguishable from virgin PET film-grade resin, enabling up to 90% PCR content.
Several major PET film suppliers offer films with 30% PCR content using mechanical recycling and 70-90% PCR using chemical recycling.
Finally, a High Barrier Film for the Circular Economy
Metallized PET films offer some of the highest oxygen and moisture barrier performance properties of any material available to flexible packaging, including foil. PCR-PET films deliver similar performance to virgin PET films and can be metallized using traditional techniques. Celplast confirmed that barrier and metal adhesion of metallized PCR-PET films match traditional PET film performance.
Since metallizing adds less than 0.1% by weight, the aluminum layer doesn't impact overall PCR content percentage. Celplast offers certified high barrier FOILMET® and DURAMET®, and high bond SUPERMET® and ULTRAMET® metallized PET films in PCR versions, available in 30-90% PCR content ranges.
— Dante Ferrari, President, Celplast Metallized Products Limited