Printing inks are an important part of plastic packages in terms of appearance and functionality. The functionality contribution of inks and coatings is key to enable circular packaging solutions following the principles of reduce-reuse-recycling. However, they also pose a major challenge when it comes to manufacturing a plastic recyclate of sound quality from post-consumer or industrial packaging waste.

Ralph Detsch, CTO at Siegwerk Group, shares latest insights about the concept of circular packaging industry in a Q&A session conducted during the webinar, which was moderated by Sriraam Selvam of PrintWeek 

Q. What is the perfect sustainable packaging solution?
In a circular economy, you have to follow the sequence of the 3Rs: reduce-reuse-recycle. Recycling is the only acceptable end-of-life scenario with a clear target to keep the material in the technosphere cycle on the highest possible quality level.

Q. Are there any specifics when it comes to recycling? 
Within recycling, you have to look for recyclability and the recyclate quality for an existing application and market. As of today, mechanical recycling is a dominant technology, but it requires mono-material structures. Thus, there is a strong focus on polyolefines and polyester depending on the different packaging types. 

Q. In that case, how can you increase the quality of the recyclate? 
This is where the process of de-inking kicks in, as it increases the recyclate quality. For laminates, one can consider de-lamination primers, but ideally, surface printing is the way to go, as it reduces the number of layers and eases the process of de-inking. 

Q. What are the challenges after completion of surface de-inking? 
Once the ink is removed from the surface, it is essential to ensure these separated ink particles remain separated – ensuring the washed off ink particles aren’t sticking back to the plastic package or contaminating the washing water. This is a key element to be considered while developing inks along with the aspect of steering the de-inking processes. Both go hand-in-hand. 

Q. De-inking is an important part of circularity. Is this already done on an industrial scale for plastics? 
No, it is not an established process at industrial scale yet, but several activities are underway in the context of plastic de-inking. We are working on a new de-inking solution to be made available to the industry; you will see a range of innovations in this segment soon. 

Q. Do you see de-inking as a solution for post-consumer or post-industrial waste? 
First, it is essential to distinguish the quality of waste into industrial or post-consumer. The industrial wastes have more clean material streams, which is a big advantage compared to post-consumer wastes. Nevertheless, the increasing demand for high-quality recyclate will also need quality improvements in post-consumer recyclates. Cleaning, sorting and de-inking are the key enablers. 

Q. How can this segregation and sorting mechanism be bettered? 
Marking of packaging materials, especially digital watermarking, has a high potential to revolutionise the possibilities of sorting and separation. It enables the tracking and tracing of every package and facilitates further recycling processes. This is an example where digitisation and circularity meet each other. 

Q. Is Siegwerk working on any such digital watermarks? 
Yes, we are part of a Holy Grail 2.0 initiative, which focuses on digital watermarks. I expect this initiative to revolutionise track and tracing, which is a key for sorting and managing materials – an essential process in waste management. It can also help manage logistics and increase the “item per minute rate” at the cash desk in a grocery. Digital watermarks do not require any additional material, unlike other marking technologies. Here, you print or emboss a certain pattern, which can be easily read and accessed via mobile applications and devices. 

Q. How do you see chemical recycling versus mechanical recycling? 
Mechanical recycling is an established recycling technology, volume-wise, it will be a dominant technology for the coming years. Chemical recycling is still in a development phase and it also has a higher carbon footprint due to the higher energy demand. 

Q. Is there a way in which both methods of recycling can support each other? 
Chemical recycling has the potential to deliver virgin quality recyclate even for direct food contact materials. Chemical and mechanical recycling can support each other as a blend of virgin quality chemical and mechanical recyclates can enable higher volumes of mechanical recyclate for a range of applications. Chemical recycling has also specific requirements on the quality of the material input, especially the catalyst, as it is sensitive to specific substances. 

Q. Can multi-material structures be a part of a circular economy? 
The strategy for mechanical recycling has to focus on recyclable mono-material. If you don ́t have a mono-material solution available you might think about multi-materials which can be separated via appropriate packaging design and separation technologies. However, the concept of modular packaging where different parts of the packaging go into separate mono-material recycling streams is interesting. 

Q. Do you see a knowledge gap concerning processes and practices for sustainability? 
Companies are progressing in certain steps of the industrial processes such as the development of new material structures for recyclability, but some activities are not fully connected with material streams. The industry must understand that the key to achieving a circular economy is to analyse the end-to-end process picture and if materials are not collected and sorted, they cannot be recycled. This requires a new understanding of cross-industry collaboration. 

Q. When we talk about a value chain, isn’t it essential to create a sustainable business model that would be viable to all? 
Yes, in a circular world, one might have to invest at a certain point in the value chain, but the benefits of this investment would be generated somewhere else, maybe from two or three steps ahead in the value chain. Thus, while creating sustainable business models, we also have to share and promote economic value creation in such a circular world. This is one of the biggest challenges in our industry. One must learn that circular economy isn’t just about the materials; it is about developing viable business models. 

Q. Could we use inks or overprint varnishes to enhance the sorting rate of plastics? 
This aspect is related to the context of marking. One can put markers into inks and coatings such as fluorescent or infrared readable markers. But how many combinations can you generate by doing this? There’s a limitation. Now, how does this marker fit into the circular material scheme? How do you make sure, that you don ́t contaminate the whole material stream? We need to avoid that we add linear materials to a structure which needs to be separated again. If such additions are done to tackle counterfeiting, then it’s a different story. But if the focus is on track and trace, I see a clear advantage for digital watermarks.

Q. What are your views on the recent BIS ban on toluene-based inks for food packaging in India? 
The ban is a milestone for India. It is an area in which we have worked for a long time to ensure safe food packaging and working conditions. I appreciate and welcome this decision. Now, we have to manage this transition together with our customers and market partners. The switch to toluene-free inks is a great opportunity to look into process efficiency improvements in all ink-related areas in the ink room as well as on press. 

Q. The role of digital printing in a sustainable future... 
Digital printing will grow in packaging printing. Today, there is already a substantial share in label applications, but there are also interesting developments in other packaging structures based on paper or plastics. Digital printing can play a key role in late-stage customisation of packaging which could help in reducing a generation of obsolete stocks in a fast-moving consumer goods industry. You can also think of digital printing in reuse scenarios for packaging. All these factors contribute to the circular economy goals. 

Q. What is your take on the carbon tax in Europe? 
Opting for circular solutions has a certain challenge in terms of cost. For instance, recyclates have lower cost today in comparison to virgin materials due to low crude oil prices. Thus, to progress in the path of circularity, we need a market environment which allows us all to have a healthy competition. To ensure the same, we need regulations, which are globally aligned to generate profitable businesses. So whether it is carbon taxes or the Extended Producer Responsibility fees, all of them play a crucial role in enabling the push for sustainability while providing an economic environment for a profitable business. 

Q. Why are people worried about plastics in our oceans rather than climate change?
Both topics are very important. Climate change is the biggest global challenge, but it is linked to the plastic waste problem. When one talks about circularity the core focus should be on a climate-neutral circular economy and also the utilisation of renewable energy. We have to keep this point in mind, because whatever we are producing or manufacturing, we need energy to make it happen, for which renewable energy is the way forward.