Challenges in the machinability of alternative packaging materials

Packaging can be sustainable in different ways. Less raw material, another material or fewer resources consumed. However, one thing links them together – at machine level, manufacturers have to consider and adapt a few things.

Cardboard trays for cookies cost four cents to make, while their plastic equivalent costs just half that amount. (Image: Schubert)

Last year’s Fachpack was held under the central theme of "Environmentally Friendly Packaging". We asked companies at the trade show about this very topic. However, not what current alternatives there are to the previous packaging, but what a manufacturer must consider on a machine level when converting to sustainable packaging.
What consumers don’t think about when they reach for their potatoes in the supermarket is how the packaging producer has had to rethink at the machine level so that they can now carry the tubers to the checkout wrapped in paper instead of plastic net.

We asked the companies about processing two different sustainable alternatives: plastic monomaterial and natural fibers.

Cookies in cardboard trays

Schubert Packaging now also offers users many machine-based solutions for cardboard packaging, which previously tended to be made of plastic. These include cardboard sleeves for drinks, cardboard holders to present cosmetic jars upright and trays for muffins and cookies, for example.

Werner Schafauer, who is Sales Account Manager at Gerhard Schubert, explains, "Cardboard trays for cookies are generally more complex to produce because they require more machine functions. The plastic trays are already preformed and only need to be unstacked from a magazine and then filled. In contrast, the corresponding machine must first fold the cardboard trays and, depending on the design, also glue them or provide them with intermediate webs, which serve product protection or presentation purposes. Since the cardboard trays come into contact with food, the cardboard is coated with PE, which, however, must not be applied to the gluing points, otherwise adhesion during the gluing process is impaired."This extra machine effort is reflected in the price. According to Schafauer, a cardboard tray costs about four cents to produce, while a plastic tray costs just two cents. A positive point is that the cartons are usually stocked flat in a magazine. As a result, more trays fit into the magazine and more can be processed at once, which increases output accordingly.

Paper can be used to form not only boxes or trays, but also blisters. (Image: Syntegon)

Paper tubular bags

Syntegon is also concerned with sustainable packaging and offers users corresponding machine systems. In an interview, Torsten Sauer, Project Manager Sustainability, explains: "Paper has a higher frictional resistance than plastic and therefore tears more quickly. In order to be able to process paper on form, fill and seal machines with no or minimal loss of speed, the molded parts are specially designed. In addition, the material is generally stiffer than plastic, which makes it more difficult to mold. To still achieve good forming, more elastic papers combined with gentle folding mechanisms in the machine help."

In addition to solutions for natural fibers, Syntegon also produces packaging machines geared toward monomaterials. "Here, the sealing pressure and the sealing profiles have to be designed differently than with composites. On the other hand, packages made of monomaterial can only be sealed securely in a narrow temperature range – using sealing systems that are adapted accordingly."

Film made from industrial or post-consumer recyclate requires minimally higher temperatures for sealing than monofilm. (Image: Beck Packautomaten)

Ticker on sustainable packaging concepts from retailers and brand owners

A look at the shelves in the supermarket shows: Brand-name companies and retailers are increasingly turning to sustainable packaging. Whether it’s recyclable packaging, the use of resource-saving solutions, or the elimination of plastic, there are numerous examples. Read more in our ticker about sustainable packaging solutions at the point of sale. Click here

Consider sealing properties

Bulent Kasap from Sudpack also knows this. "When producing films from mono-material, the challenge is to adjust the sealing properties of the films so that a secure seal can be ensured on standard packaging machines without damaging the film during the packaging process. Another challenge is to ensure the mechanical properties to prevent the films from tearing during processing, for example. By using raw materials with mostly lower density, the films are generally lighter and thus offer advantages throughout the supply chain. Another aspect is that in order to reproduce the above-mentioned properties using mono-materials, special polymers often have to be used, which is often reflected in higher manufacturing costs."

Recycled mono-material

Beck Packautomaten not only offers users machine solutions for packaging made of plastic monomaterials, but goes one step further and also has machines in its portfolio that use recycled material for packaging.

"The easiest way is with industrial recyclate, because you know what’s in it," says Beate Beck-Deharde, who is the company’s managing director. "With other recyclate or post-consumer recyclate, irregular structures of the film may require different welding temperatures and pressures, which then lead to uneven welds or even holes in the seam."Expertise is therefore required in this respect.

The pressure applied by Beck’s machines during sealing is always the same for monofoil, industrial recyclate or PCR film. The latter two types of film require minimally higher temperatures for sealing. And again we get the answer that for paper, because of the small contact area, the user needs much more pressure and temperature than for film.

Some users prefer to use paper packaging instead of recycled mono-material, and Beck offers machines for this purpose as well. Ms. Beck-Deharde explains how this packaging is processed: "The paper is either coated with polyethylene or acrylic dispersion, and this coating is melted on for sealing. At the same time, the coating makes up only 5% of the total material. The paper can be disposed of in the waste paper and is fully recyclable. In addition, the coating acts as a stabilizer for the paper. In the process, we have adapted our proven machine technology to the paper."

Packaging machinery manufacturers are already working hard to provide users with solutions to make packaging easy to recycle and therefore more sustainable. But whether manufacturers use plastic monomaterials or natural fibers, the machine conversion to sustainable packaging is not as simple as reaching for the potatoes wrapped in paper instead of plastic at the supermarket.

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