Recyclable-by-design “not enough”: Gualapack and Tomra prove mono-PP spouted pouch recyclability

09 Aug 2021 --- Gualapack and Tomra have proven the recyclability of Gualapack’s monomaterial polypropylene (PP) spouted pouch through all treatment stages of a DKR (Deutsche Gesellschaft für Kunststoffrecycling) rigid PP waste stream.

Combining monomaterial laminates and semi-rigid multi-layer components, Gualapack’s pouches showed they can be automatically managed for recycling in a rigid PP stream.

“We had to make sure that [the pouches] would be recyclable in practice, that is, in a real-life scenario. For our clients, each in their own nation, it is not enough to say that a pouch is recyclable by design,” Michelle Marrone, Gualapack sustainability manager, tells PackagingInsights.

“It has to be proven on local infrastructure and there has to be technology in place that can identify the pouch as a PP and separate it into the correct waste stream, even when the pouch is mixed among other types of plastic packaging waste.”

Testing with Tomra
As a first step, different percentages of Gualapack pouches were added to rigid PP waste, which was then processed through Tomra’s Autosort. This sensor-based sorting machine confirmed pouches are well identified as a PP material. Notably, over 80 percent redirected to the rigid PP stream.

Tomra’s Autosort advanced sensor-based sorting technology provides optimized results in packaging sorting PE and PP recovery.“To determine whether the new pouches could be sorted with optical sorters, we added a significant amount of them to a combined separate source and mixed waste stream sorting plant for automated sorting,” explained Jürgen Priesters, senior vice president of business development at Tomra Circular Economy.

A waste PP bale with 5 percent additional pouches and a bale without any pouches were compared in a back-to-back trial encompassing all the steps of a standard recycling process.

The two bales were shredded into flakes and hot-washed with water and sodium hydroxide at 85 °C (185 °F). Next, they were post-sorted through a second Autosort Flake machine from Tomra to improve the quality of the material. The two bales were then extruded on an industrial scale extruder and pelletized back to PP.

Outcome “surprisingly good”
The result was “very good detection” and “accurate separation rate of all pouches,” says Priesters. A subsequent washing and recycling trial showed that the Gualapack monomaterial pouches could be easily recycled into standard products.”

Furthermore, ink and adhesives from the pouches did not impact on extrusion, and provided high thermal stability without any odor or volatile issues.

Gualapack affirms the pelletized materials were characterized by third-party laboratories and declared comparable to PP copolymer grades suitable for injection molding.

No one-for-one material swap
Packaging that is recyclable-by-design continues to pique industry’s interest: Gualapack assisted Kraft Heinz in releasing a recyclable baby food pouch in June, following the packaging provider’s collaboration with Nestlé in March 2020.

Spouted pouches are becoming increasingly popular for baby food manufacturers, where environmental sustainability is becoming just as important as product safety and convenience.

Tomra and Gualapack are both members of CEFLEX, the European platform for the Circular Economy of Flexible Packaging.There are several technical challenges to create a monomaterial all-PP pouch to begin with, says Marrone. “[This is considering] that we are substituting different layers such as PET as a printed surface, and aluminum for light and oxygen barrier with PP.”

“This meant having to select different grades of PP that could serve the different purposes within the same polymer family and be processed on existing machines without having to change our lamination, pouch making and sealing technology,” she outlines.

Step up recyclable packaging
Making plastic more recyclable is becoming increasingly more urgent as global aquatic environments are littered with the material.

A study from Wageningen University and Research in May revealed plastic packaging recyclability has not increased in the Netherlands alone over the past seven years.

However, Marrone points to Tomra’s testing as a PP recycling solution with global appeal. “Providers of packaging solutions can design their packaging to be a monomaterial that is recognized by state-of-the-art sorting technology such as Tomra.”

“Packaging that is 90 percent (or more) made of a single material such as PP, polyethylene, polystyrene, or PET, will be correctly identified and separated into a waste stream that can be destined for recycling and a second life,” she concludes.

By Anni Schleicher

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