Siegwerk's coating drive to embrace circular packaging

Barrier coatings play a crucial role in various applications, including sustainable alternatives to complex packaging structures using plastics. These coatings enhance fibre-based materials by resisting external aggression such as water, moisture, grease or oxygen, and/or maintaining the internal condition of a packed product.

In the case of plastic based packaging and particularly flexible packaging, barrier coatings enable us to reduce plastic layers, reduce plastics and microplastics. It allows simplifying complex packaging to get better recycling and so a second life through a circular economy. The introduction of bio-sourced barrier coatings allows us to lower the carbon footprint and reduce ecological impact.

Barrier coatings enable the value chain to rethink packaging to better reach the higher recycling target and implement a circular economy.

Multiple chemistries can be used to get barrier properties on different substrates — water-based barrier coatings as dispersions (for example; Acrylics, EEA, Styrene Butadiene, EVA, PVDC, etc) or water-soluble coatings (for example; PVOH) are most common for paper and paperboard. Solvent-based coatings are also possible, for example; for use on polyolefin and other types of plastic films. At Siegwerk we are always looking for the most suitable chemistry for each application considering sustainability, performance, and safety. Not all materials which can be used, should be used, especially when it comes to food packaging.

Different products are compatible with different printing methods or coatings processes. Flexo or gravure printing offers lower deposit capacity and typically requires low viscosity with high dry content. On the other hand, an offline coating machine can often allow reaching a higher deposit with higher viscosity as long as the drying capacity is sufficient. Depending on the targeted performance, paper-based substrate, and end-of-life product management, the application method must be chosen carefully.

In terms of the minimum gram of coat weight needed, a window from 4–15-gsm dry can be considered. It depends on substrate selection, application method, product layer numbers, barrier chemistry and performances to be achieved.

It is important to consider the impact of cost on the total solution and in the context of other important factors like sustainability and safety when considering switching from lamination to coating.

In addition to the sustainability benefits of using coatings to simplify packaging structures; coatings offer a wide range of performance possibilities and can be applied at multiple stages in the value chain using a range of application methods.

All our coatings are certified for repulpability according to the German PTS-RH:021/97 Cat II method and we are on the way to certifying our product with the harmonised CEPI method as well.

Products proposed in India for paper-based application must be checked by the CPPRI (Central Pulp & Paper Research Institute). Several of our coatings are being tested now. Biodegradability and industrial compostability are two properties of interest in some applications, but they need to be considered case-by-case as it is not always the best way to support a circular economy.  As our products are developed for Direct Food Packaging applications, migration tests are carried out. Our products are developed to be compliant with EU regulations for the export market.

Since the beginning of 2023, Siegwerk has shared information about the Product Carbon Footprint (PCF) of its products. Siegwerk’s approach is supported by ISO norm 14067: 2018 and is GHG protocol compliant. The values we can provide are a "cradle-to-customer gate" approach so they do not reflect printing and drying emissions.

So, we can provide scopes 1, 2, and 3 and value for transportation to the customer gate. In addition to our PCF values, information about the biogenic carbon is given to consider the emission-saving effect of raw materials based on bio-renewable sources.

About the recyclability scorecard as said all our portfolios pass the German PTS test as recyclable when applied at a packaging weight of 5-6%. Regarding the CEPI scorecard, the first products tested are “Best in Class” listed and are reaching a CEPI scorecard of >97%.

Viscosity, deposit homogeneity and drying condition have to be controlled as for lacquers or inks. If there is any knowledge gap in the market, our teams of application experts are ready to support Siegwerk customers who have queries about the application process (both printing and coating).

The share of polymers in sustainable food packaging applications is expected to reduce by 50% over the next two decades. Meanwhile, paperisation is also a strong trend, and fibre-based materials are projected to contribute up to 40% of all materials in use for food packaging. This is boosting our R&D effort as we invest to develop solutions which enable circular packaging for our customers now and in the future.

The prospects are huge. We are already working on the next product generation development. We believe responsibly managed renewable resources will be one important key to unlocking sustainable packaging development regulatory compliance, but until we reach this goal with commercially available resources and effective application methods, we continue to improve our second-generation products to get a good economic and performance balance.

Barrier properties offer valuable protection, but understanding their limitations and optimising their performance is essential for sustainable and effective packaging solutions.

The exact size and value of the coatings market for paper and packaging substrates in India is debated, but we can agree that it is already quite big and it will grow significantly in the future.