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Aug 22, 2023

W&H looks for easier options for blown film

Windmöller & Hölscher KG ran three live blown film demonstrations each day at K 2022, while simultaneously running one cast and five blown film lines at its Expo 2022 open house in nearby Lengerich.

Windmöller & Hölscher KG ran three live blown film demonstrations each day at K 2022, while simultaneously running one cast and five blown film lines at its Expo 2022 open house in nearby Lengerich.

Düsseldorf, Germany — Windmöller & Hölscher KG has managed well during the COVID-19 pandemic, maintaining its traditional long-term growth by increasing annual sales from 901 million euros in 2019 to 968 million euros in 2021. The producer of blown and cast film extruders and flexographic printers is based in Lengerich, Germany, and has 3,221 employees.

At K 2022, the company ran three live blown film demonstrations each day, while simultaneously running one cast and five blown film lines at its Expo 2022 open house in nearby Lengerich.

Dominique Alhäuser, corporate communications manager, explained that increasing remote access to customers' machines was key to growth during the pandemic. Once a gateway has been opened, the customer has to grant access to W&H before it can adjust process parameters. There is also a visual service assistant app since 2019, enabling processors to show W&H via a video feed which controls are in operation or need activation.

But both Alhäuser and Lennart Ederleh, blown film machinery technical sales director, stressed that digital communication can never replace direct person-to-person communication. This is not always easy to achieve against a background of increasing difficulty in finding new employees and challenges in developing new film solutions.

At K, W&H focused on meeting challenges within a circular economy loop. Ederleh explained that while efficient production with high degrees of automation and digitalization contributes to sustainability through lower scrap rates, it is important to discuss packaging design for mechanical recycling, in view also of lot-to-lot variability when using recycled content.

Ederleh also referred to replacing multimaterial with monomaterial solutions that remain suitable for food packaging by having oxygen barriers. The task is not easy, as most barrier materials are not considered recyclable, Ederleh said, adding that EU regulations do not permit more than 5 percent of foreign substances in recycled film.

This has been a problem, with some specialty films needing much more than 5 percent content. A research project with BASF started looking at compatibilzer use, in order to at least enable film with nylon barriers to be recycled into injection molding applications. But this approach can now also apply to film-to-film recycling, Ederleh advised, if not yet for food contact.

There are ways to get round the 5 percent limit. W&H established that stretching film with machine direction orientation alone contributes to some barrier improvement and Ederleh talked about stretching with use of a thin coextruded EVOH layer, well within the 5 percent limit, as well as using W&H flexographic printing expertise to print a PVOH barrier.

Alhäuser stressed: "Using less layers doesn't necessarily mean less materials, and less layers is not a prerequisite for recyclability. People get confused, thinking that if you only have one material, it means only one layer. As we showed at K 2019 and now again at K 2022, the films shown all have more layers in order to provide the functionality you require for the packaging."

Ederleh expanded on this by saying: "When it comes to three-layer film, we clearly see that the playground you are getting in terms of recipe optimization and film properties is larger with five layers, and that benefits high functionality and recycled material introduction into the film structure.

"When it comes to a larger number of layers, we are typically talking about barrier film and then in the past these were PA [nylon] or EVOH barrier layers, which needed more than seven, or more than nine layers in some cases," he said.

Ederleh's opinion is that as there is demand for high-barrier applications in the market, multimaterial and multilayer structures will not completely disappear from the packaging market. But W&H also talks about and researches into monomaterial solutions with industry partners, especially in terms of recyclability.

Ederleh says W&H is investigating how much post-consumer recyclate can be used in industrial and nonfood-contact packaging film and has managed to produce 50 percent PCR-content collation shrink film with the same thickness, properties and functionality as conventionally used virgin plastic film.

"The film gives perfect mechanical properties, but there are some minor optical defects. In fact, a small amount of haze and gel irregularity here and there is often wanted and can be a sales argument for brands to show they use recycled material. It's not necessarily something to avoid, as it can be a sign of a sustainability," he said.

A bottle six-pack at the booth is on shown wrapped with 50 percent post-consumer recyclate PE shrink film, production of which runs on an Optimex II line in Lengerich, supported by a Novoflex flexographic printer. Alhäuser said Optimex is an optimized line for PE that produces three- and five-layer film in widths up to 2.6 meters, while the larger Varex II can produce films with seven to 11 layers up to 3.6 meters, observing, "It can do anything and can be more easily tailored to different applications."

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