Countless items in both the food and non-food sectors are now packaged in stand-up pouches - soap, nuts or smoothies, for example. The classic material combination for such packaging is PET/PE. The two films are produced individually and then bonded together. While the PET in these multilayer laminates provides good rigidity and appearance, the PE serves as a sealing film - a combination that ensures excellent functionality but is problematic for recycling: While manufacturers today usually recycle the production-related scrap from their monomaterial films directly back into the extrusion process, this is not possible with PET/PE composites. As a result, large quantities of material are lost to the industry. The hurdles for recycling this post-industrial waste are primarily the following:
Recycling hurdle 1: PET and PE are chemically incompatible
PET and PE behave chemically in much the same way as water and oil. When melting the material again to produce a homogeneous mixture, which is absolutely necessary for the extrusion of a film, is not easily possible.
Recycling hurdle 2: Packaging is printed
Rejects that are produced during further processing into finished packaging are usually printed with printing inks that consist of a wide variety of components, such as color pigments, additives and various binders. Some of these elements gas out during melting in the extruder. This is a problem for stable extrusion - bubbles and holes form in the film. For printed film, regardless of the raw material, the following therefore applies in principle: in the single-screw extruder, a maximum of 20 percent of this material can be added as recycled content.
The solution: EVO Fusion technology
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With EVO Fusion technology, Reifenhäuser now offers film producers a technology that makes the previously impossible possible: recycling PET/PE laminates. To reconnect PET and PE after melting despite chemical incompatibility, the line makes use of twin-screw technology. Christoph Lettowsky, product manager at Reifenhäuser Blown Film, explains: "Twin-screw extruders break down and distribute the components of the input material much better than single-screw extruders. Thanks to the excellent mixing effect, it is possible to distribute the PET content of 10 to 40 percent, which is common for laminates, evenly in a PE matrix, thus creating a homogeneous mixture - the prerequisite for producing a new film."
EVO Fusion also masters the second challenge - degassing from printing ink - thanks to twin-screw technology. Twin-screw extruders offer a significantly larger free surface in the outgassing zone than single-screw extruders. The surface is also renewed much faster, so that a high degassing performance is achieved. It is sufficient to completely remove the interfering components of the printing ink.
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| From Post industrial recyclate to new, high-quality packaging |
The field of application: EVO Fusion is particularly worthwhile for producers with extrusion and converting under one roof
While around two percent of scrap is produced during the manufacture of a film, up to 15 percent is produced during further processing into finished packaging. Today, producers have to dispose of this waste for a fee. With EVO Fusion, the previous waste becomes valuable post industrial recyclate, the quantity and quality of which is very predictable and plannable. Christoph Lettowsky says, "The technology is fun from 50 to 60 tons of waste per year. The ideal is 100 tons of waste per year. Evo Fusion is therefore particularly interesting for producers who have extrusion and converting under one roof."
Producers can use Evo Fusion to turn their PET/PE scrap directly back into a new film that can be laminated against a PET film. For example, a stand-up pouch for soap can become exactly the same product again. "With EVO Fusion, high quality is maintained. Downcycling, which is otherwise common, is not an issue. We have already worked with customers to produce films 20µm thick, which are ideal as outer packaging for hygiene products or dishwasher tabs," says Lettowsky.
