The Polifilm Group has been recycling offcuts, start-up sheet and other production scrap for many years - the company is an international expert in extrusion and protective film solutions. However, recycling becomes difficult with coated films, such as protective films for high-quality materials. These films have a special adhesive coating and therefore adhere extremely well to sensitive surfaces, such as stainless steel, glass, metal or plastic, and prevent the surfaces from damage during processing, storage, transport or assembly. However, it is precisely this adhesive coating that poses a problem in recycling.
"Basically, adhesive-coated films can also be recycled into granules using tried-and-tested processes - but the adhesive remains in the material as a foreign substance," explains Polifilm's recycling expert Andreas Schramm. "The granules can stick or, in the worst case, may produce a large block that makes it impossible to process." The risk increases with the amount of adhesive used per square meter and depending on the adhesive system used. "That's why we’ve been unable to recycle our scrap from the production of adhesive-coated films," says Schramm.
Polifilm was not satisfied with this state of affairs: "On the one hand, disposing of production scrap instead of recycling is a negative cost factor. On the other hand, we are aware of the impact we have on the environment and society. We are well aware of our responsibilities," says Schramm. That’s why Polifilm has set itself the objective of increasing the proportion of recyclate in its own products and closing internal material cycles – including adhesive-coated films.
Increasing the proportion of recyclate: How this works in plastics extrusion
Plastics producers are under increasing pressure to increase the proportion of their recyclate. In the process, they are often caught between the conflicting priorities of sustainability and economic efficiency. The Reifenhäuser Group manufactures highly flexible extrusion lines and robust components as a solution to this conflict. The lines are capable of converting a wide range of recycling raw materials reliably.
tonnes p.a. recyclate were processed at Polifilm in 2019
tonnes p.a. recyclate were processed at Polifilm in 2019.
times the quantity of processed recyclate by 2027.
The leading role here is played by the Recycling Business Unit founded at the Weissandt-Gölzau site in 2019. The business unit is headed by Andreas Schramm, who took on the challenge of adhesive-coated films in 2020. The experts around Schramm are researching, experimenting with different film coatings, or adding additives to the recycling process. However, these approaches have so far failed to produce a solution to improve recyclability and also meet Polifilm's quality requirements
In the end, a contact with Reifenhäuser came about quite by chance. Polifilm's recycling team described the challenge - Reifenhäuser's blown film specialists presented their EVO Fusion twin-screw technology. The technology allows manufacturers to process highly contaminated and inhomogeneous recyclates [LINK STORY 5] – such as adhesive-coated film residue. "Normally, low-quality recyclate can only be mixed to a small extent with virgin material or other recyclate of higher quality on a mono-screw," Kilian Sieling, Area Sales Manager at Reifenhäuser. "However, our twin-screw technology achieves a high degree of degassing and better mixing. This means manufacturers are less dependent on the quality of the recyclate."
Three benefits of fluff-to-film:
In addition, the technology allows the direct processing of film residue and film scrap, known as fluff, to produce new film. "There is a significant difference between the fluff-to-film process and previous recycling processes, where recyclate is first melted and then granulated," explains Kilian Sieling. “Our EEVO Fusion twin-screw technology
allows us to simply skip the re-granulation stage." From Polifilm's point of view, this is a major benefit: "We save a very energy-intensive process step." emphasizes Schramm. "Here, we're talking about significant economic benefits in view of the current rises in energy prices – and we save substantially on carbon emissions.”
In the fluff-to-film process, new film can be made in a single step from film scrap, known as fluff, without the need for granulation and pre-drying. The secret to the success of the EVO Fusion twin-screw technology is its high degassing performance and mixing function.
Added to that, the process has a positive impact on the quality of the film produced, explains Schramm. In the regranulation process, the recyclate is shredded, heated, and cooled. In the following production process, the granules are then reheated and recooled. On the other hand, the fluff-to-film process shreds the recyclate cold and only heats it in the production process when it is extruded directly to film. "This process protects the polymer structure and improves the quality of the film," explains Schramm.
Polifilm was already convinced by the concept in theory. The next step was a series of practical trials at the Reifenhäuser Technology Center in Troisdorf. Experts from Polifilm, Reifenhäuser and a manufacturer of plastic film shredders collaborated to find the right shred size, the best ratio between recycled raw material with and without adhesive residue, and the optimized line settings.
A one-week continuous operation was then scheduled as a stress test in the fall of 2021. "We already knew from our preliminary tests that we would definitely need a three-coat system to prevent the adhesive from migrating to the outside. In that case, the rolls in the line would stick," explains Schramm. The stress test investigated certain factors, such as the extent to which the adhesive becomes noticeable as a contaminant when it is co-extruded with other recyclate. The results of the test: The film can be further converted without any problems. "This was a great success for all of us and a great team effort," said Kilian Sieling from Reifenhäuser. Polifilm's recycling expert Schramm also confirmed this: "We make a good team: We are both medium-sized companies that are pragmatic and down-to-earth in a positive sense, that simply test things and deal with each other openly for the sake of making progress in this important task - namely, to close cycles and reduce energy consumption."
Before joining Polifilm, Andreas Schramm held various management positions at GE and McDonald's. He has also worked as a consultant on projects in the automotive industry and the renewable energy sector.
In a first step, Polifilm wants to use recycled film to produce 120-liter garbage bags, the kind used in garbage cans on highways and rest stops, for example. "At first, it sounds like a very banal, simple product. But that’s not the case at all," says Schramm. "Garbage bags have very high tensile and tear strength requirements." In addition, the garbage bags should be much thinner than the industry standard but should retain the same functionality.
tonnes p.a. is Polifilm’s target for the production of adhesive-coated film from production scrap.
million garbage bags can be produced from this tonnage.
That's how many years of experience Polifilm has under its belt in the production and marketing of garbage bags.
"We want to learn as much as possible from the production of garbage bags because the project serves us as a blueprint for other applications.” After all, Polifilm does not want to stop at producing garbage bags by any means. "The garbage bag is a bridge product for us - if it works out, we want to move toward higher-grade applications. At best, we will achieve equal cycling, that is to say, we will also produce new surface protection films from adhesive-coated film residue."
"The garbage bag is a bridge product for us - if it works out, we want to move toward higher-grade applications.“
Currently, a new production hall is still under construction at the Weissandt-Gölzau site so that recycling and extrusion can take place in close proximity. By the end of 2022 at the earliest, Polifilm will then start the recycling process for adhesive-coated films - and that will be a premiere for the fluff-to-film process on an industrial scale