Way2K: Industry interviews in the lead-up to the K 2022 trade fair

"We can reduce the CO2 footprint with plasma"

Mr. Buske, what are the ecological benefits of plasma surface treatment?
With plasma technology, we can completely replace environmentally harmful solvents in production processes. Many material surfaces need to be specially pretreated before they are further processed to enable bonding, printing or painting. Among other things, our focus is on the surface treatment of plastics. Many plastics, such as polypropylene or polycarbonate, are non-polar. This means that without pretreatment, adhesives, varnishes or paints do not adhere well. In industrial processes, chemical adhesion promoters, so-called primers, are therefore often used, which contain 80 to 90 percent solvents and pollute the environment. Using our plasma technology, which only requires compressed air and electricity, this chemical pretreatment can be dispensed with.

How does treatment with plasma work?
Plasma technology works according to a simple principle of physics: additional energy causes states of matter to change. If further energy is added to a gas, it is ionised and changes into the high-energy plasma state as the fourth state of matter. When plasma with its high energy level comes into contact with materials, the surface properties change. Oxygen- and nitrogen-containing groupings are introduced into the largely non-polar plastics to increase their surface energy. This so-called activation improves the wettability of the surface, thereby causing a significant increase in adhesion and consequently enabling adhesives, lacquers and paints to have long-term stable adhesion. A plasma system usually consists of a generator, a transformer and a nozzle that is precisely adapted to the respective treatment.

Apart from saving solvents, are there other advantages in terms of sustainability?
With our plasma nozzles, we can pretreat large areas, and with extreme accuracy, thereby sparingly pretreating only those parts of the substrate that are to undergo further processing. In the plastics sector, components are often prepared using other pre-treatment methods such as flame treatment for example, in the production of dashboards for the automotive industry. However, the flame treatment process requires a lot of gas, and a corresponding amount of CO2 is released. With our plasma processes, we can replace this process and greatly reduce the CO2 footprint in the production process. Our systems only require electricity and compressed air. So, if a user works with green electricity, our method is CO2-free.

Are many clients already doing this?
Many production lines already run on 100 per cent regeneratively produced electricity. We are increasingly asked for concepts that support the replacement of environmentally harmful processes with plasma technology. A rethink is taking place across all industries in the direction of improved energy balance and CO2 reduction. Companies are increasingly under pressure from their customers to operate more sustainably. Cost efficiency is still the focus here.

Companies are also under pressure to make greater use of recyclates. Can plasma technology be used here as well?
If a product consists of recyclates to a certain extent, this is now a selling point for the supplier. For example, many car manufacturers use a certain proportion of recycled materials in their interior designs. Many manufacturers even specify the recycled content for components to their suppliers. This has an effect on processes such as bonding, printing, painting, labelling, applying seals and more. Various manufacturers are therefore now using our plasma technology. In many cases, plasma pretreatment makes the use of recycled plastics possible in the first place, and in doing so, contributes to more environmentally friendly, resource-saving production processes.

Do the surface properties have any bearing on plasma technology?
We can get a lot out of a surface that does not actually have the properties required for the downstream processes. Together with the injection moulding equipment manufacturer Arburg, we demonstrated this at the Digital Edition of the 2021 Hannover Fair: a drinking cup made of recycled PP, manufactured by Arburg using injection moulding, and with a crumpled look, i.e., with a very irregular surface at that, was printed using UV digital printing without the use of additional adhesion promoters. For this purpose, the recycled cup was treated with Openair-Plasma after removing it from the injection mould. The highly effective activation of the print surface creates the prerequisite for good adhesion of solvent-free inks, even on irregular substrates made of non-polar recycled PP. The result is a brilliant, sharp print image that is permanently resistant to abrasion and moisture. All in all, with highly diverse materials, we succeed in most cases in preparing the surface well for subsequent processes by cleaning and activating it with the help of Openair-Plasma. If this surface treatment is not sufficient, we can remedy that through our PlasmaPlus process. In this process, a so-called precursor is fed into the plasma. We apply a nanometre-thin layer to the surface and can therefore apply an additional function, for example an adhesion-promoting coating.

Where in the circular economy do you see challenges?
A major challenge lies in the separation of materials by type for recycling. This is where plasma technology takes on a special significance: because sorting is not always 100 percent homogenous, plastics are produced during the recycling process whose properties are slightly different from those of virgin materials, for example in the quality of the surface. This impacts the subsequent processes. With plasma treatment, we can help make these downstream processes possible.

 

Lukas Buske - Head of Applications

Industry interviews on the road to the K:
The world is facing major challenges: Climate change must be fought; the environment must be protected, and resources must be conserved. It is also important to make good use of the opportunities offered by digitalisation. The plastics industry has a key role in this process because plastics are ubiquitous in the world.
Climate protection, digitalisation and the circular economy are therefore also the three major topics at K 2022, the world's leading trade fair for the plastics industry. To get in the mood for the industry meeting in autumn 2022, the VDMA is letting representatives of the plastics machinery industry and all other stakeholders in the sector have their say through weekly interviews.

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