The chemistry of ink that leaves no trace

Much of print relies on inks that leave a lasting mark, but while some things we print are intended to last decades or more – and we have certainly developed some incredible technologies to make this happen – there are plenty of other printed items which have a much shorter lifespan. For these, the development of biodegradable inks is essential and plays an extremely important part in both our sustainability goals and scientific innovation within our R&D hub at Canon Production Printing (CPP).

“What we're talking about is developing a new class of chemistry,” explains Tom van Dijkman, the Programme Lead for Technology Development at CPP. He and his colleagues, Ernst Ullersma and Peter Wetjens represent Canon Production Printing in a consortium of companies and academia for whom sustainable inks and coatings are also a challenge. “Working together with organisations like AkzoNobel and Evonik, plus a number of university partners, we have created the ‘SusInkCoat’ project to explore new chemistries, materials and production processes.” And while every member shares this common goal, for us there are three crucially important areas which could take print into a sustainable future.

Binding materials

These are the substances that hold pigment particles together and make them stick to a surface. “We have a dichotomy here,” Tom explains. “On the one hand, we want our ink to be super stable on the print – until we want to recycle the paper. And then we want a very low-footprint way to remove the ink at the point of recycling. For that, we need to develop a type of chemistry where we build in a ‘switch’, something that makes it possible for these materials to be de-bonded.” It’s the chemistry equivalent of a sandcastle, maintaining its structure for a time, but washing cleanly away when it’s no longer required.

“In an ideal world,” Tom adds, “we would like it to form part of the natural cycle. We know that printed materials don’t always end up where they should, even though we all strive to recycle as much as possible.” This could happen by working towards a bio-based solution – creating a circular formulation that is both derived from nature and then returns to it at the point of disposal.

Pigments

“Currently, pigment chemistry is entirely fossil based and typically results in materials that are either not biodegradable at all or have very limited biodegradability,” explains Tom. Traditionally, ink pigments have been designed to last, but this can give them an environmental footprint that is large, both in terms of their production, as well as their disposal. “We would like to find chemistries where we can make, for instance, the colour white without the use of titanium dioxide. Or to give something a metallic sheen without metals, which end up as nanoparticles.”

And the answer may well be found in nature itself. “If you look at a butterfly or bird’s wing, typically their colours don’t come from pigments,” says Tom. “The colours come from the structure of the materials that diffract the light. We want to use that same principle to achieve white and metallic effects using materials that are otherwise harmless.”

Surfactants

These are chemicals which are added to inks and paints to help them flow smoothly across a surface, as without them, they tend to bead up. The right surfactant can create a uniform, thin film that flows beautifully where it’s applied. Today, most of the world uses surfactants borne of fossil-based chemistry. “And while it’s highly effective,” says Tom, “because of the way it's designed, it’s also highly persistent.” This means that, if it ends up in nature, it's not easily broken down by microbes or UV light.

But more than that, adding these highly persistent surfactants into the environment can seriously impact the living cells in nature. “Each cell has its own natural ‘shell’,” adds Tom. “They surround bodies of water which contain all the structures that create life. And these shells can be harmed by surfactants.” This is an issue which affects all corporate members of the SusInkCoat Consortium and the race is on to find a new kind of chemistry that can give us the surfactant properties we need, but that can also be actively removed when necessary. “For us, again, we're looking for a switch,” says Tom. “We want surfactants that make ink flow until they’re fixed into place. Then we want to be able to break down that surfactant, so its environmental impact can be minimised.”

New materials for everyone’s future

Whether it’s material sciences or the development of advanced optical and printing technologies, our Research and Development teams always have an eye on our corporate philosophy of Kyosei – Living and working together for the common good. The SusInkCoat Consortium is a great example of the kind of long-term thinking and collaboration that we bring to both product development and our sustainability goals as an organisation. “This is a journey we very much take together with our customers,” Tom adds. “And by leveraging the technologies we develop, we are able to create innovative products, not just for a couple of years, but for decades to come.”

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