Removing petrochemical contents from packaging inks and coatings is a considerable challenge, with sustainable alternative materials a key part of the solution towards defossilisation.

Established practices and processes are not always easy to change. Yet if defossilisation is to become a reality in the packaging industry, brand owners and manufacturers must reduce materials derived from fossil fuels in as many areas as possible.

Paul Pain is Head of Water-Based Technology at Siegwerk, a committed global leader in circular solutions for printing inks and coatings for packaging and labels. Pain explains that while the contribution of inks to the overall carbon footprint of the packaging is often well below 5%, it all contributes to decreasing the wider environmental impact.

“We as an industry need to have a sustainable future, and must defossilise for our own purposes and existence. So, the overall contribution to the package might not be massive. But if we can defossilise, then it’s something that contributes.”

Natural-based biorenewable materials are being developed to replace petrochemicals in packaging manufacturing. More is still being learned about exactly how these sustainable materials will react to environmental factors and behave over time. Performance is the main issue, but there are sustainable products already performing strongly.

Replacing petrochemicals with biorenewable components in sustainable inks

Traditionally, materials used in packaging inks such as acrylic resins for binder systems, pigments, and additives were all made using petrochemicals. As the industry has developed during the last 15 to 20 years, these petrochemical components have been considered cost-effective and convenient, with their uses widespread. While there are considerable challenges in changing petrochemical materials to biorenewable equivalents, Siegwerk is working to address this.

“If we start first with the part that does the binding and gives the performance of the system, the resins in the inks are based on real commodity raw materials. So, acrylic acid, styrene, and acrylate monomers, they’re the things that build all of those plastics. They’re very common and it makes them very efficient in terms of their costing use,” explains Pain.

“When you go to replace those with biorenewable materials, there are different approaches. You can opt for making bio-monomers. So, in the same way you would have a bio-plastic, you can have a bio-monomer, creating a bio-resin which can be used for the printing ink.

“The other direction is to go for substitution with natural or new or novel chemistries that combine to bolster the best of the natural world and the synthetic worlds.

“Particularly for the binders, some challenges remain where you want to have super high performance. If you need high water or chemical resistance, synthetic products or petrochemical-based products are behaving the best.

“But the commodity work for paper and board for corrugated, for example, where the performance requirements aren’t very high, it is possible to almost 100% substitute with other resin types. If you look at the volume of the industry on paper, both of those things are surrounding corrugated. So, there are good opportunities to de-fossilise at least the resin parts of the system.”

One of the biggest issues surrounds pigments, which are almost fully petrochemical-based. While many components in the system can be replaced with eco-friendly alternatives, this is not the case with pigments.

“The pigment is really a stumbling block. With the exception of maybe two or three pigments, there are really no viable alternatives,” adds Pain.

While there is research into natural-based pigments, this is likely at least a decade away from being a potential option. Nevertheless, one stumbling block is not going to restrict progress elsewhere.

Sustainable inks and coatings

Demand for sustainable inks and coatings has risen within the past couple of years, according to Pain. And for sustainable packaging materials to be more widely adopted by brand owners and accepted by consumers, their performance and cost need to be comparable with components derived from fossil fuels. For this, Siegwerk has a solution.

Siegwerk’s UniNATURE brand is a range of sustainable water-based inks containing renewable carbon and made from sustainable materials for application on almost any type of paper packaging, from food wrapping and corrugated board to paper cups.

The UniNATURE range also addresses another obstacle to adopting environmentally friendly materials, which is the perception that they require changes to production methods or machinery.

“With the UniNATURE product, one of our key points is that you don’t need to do anything as a customer. Everything takes care of itself,” says Pain.

Siegwerk’s UniNATURE range features up to 50% renewable carbon content, with the plan to increase this further in future.

The future is to be as close to 100% as possible. But when we come back to an ink as it’s printed by a customer, inevitably, you need to have something between 10% and 20% of pigment to have a nice strong colour. And that will be the upper limit, we won’t be able to go further than that,” adds Pain.

Siegwerk is also developing water-based coatings that provide barrier functionality as part of the company’s plan to reduce the use of plastic and increase the use of paper wherever possible. Using biorenewable inks and coatings improves recyclability and reduces microplastics.

“When we talk about biorenewability as a package, we see this as an opportunity to extend the use space of paper,” says Pain. “What we want to do with our products is to make sure that fibre recovery rates stay as high as possible.”

Understanding the difference between biodegradable and compostable

When it comes to sustainable materials, the terms biodegradable and compostable are commonly interchangeable in the mind of the consumer. However, consumers must be informed that these are completely different things.

While biodegradable materials will break down over time, the exact timeframe is often unspecified and items are not always made of environmentally friendly materials, sometimes containing harmful chemicals. Whereas compostable packaging comprises mainly natural materials that will decompose much more quickly when placed in controlled and managed conditions.

“That’s a real challenge because we have people asking for biodegradable inks when they mean compostable, or people asking to buy compostable and assuming it means biodegradable,” says Pain. “This distinction is not well understood.”

Pain suggests that it is important for brands to be transparent with consumers about the real environmental impact of packaging. Any claims that Siegwerk makes about its products always have evidence to back them up.

“When we talk about biorenewable content, we always use a measurement of new carbon in the system. We will report only in the context of new carbon versus old carbon, and not anything else,” adds Pain.

“Our ethos is to be a reliable partner. A big part of what we do, alongside the products, is informing customers to make sure they have the information they need to make an informed choice. Because there are arguments for and against biorenewability.

“Paper is not only already one of the most recycled packaging materials globally, but it also holds great potential to offer a viable substitution for plastic for several packaging uses. By increasing biorenewable materials, we concretely support the defossilization of fibre-based packaging by reducing the use of fossil based raw materials in inks.”