New sustainable polymers: a greener future for commercial inkjet printing

Currently, the world is at a critical point. There are endless issues that require urgent attention such as sustainable materials, clean energy, and climate change. The scientific community has the ability to address these challenges, including the responsibility for the maintenance of our planet.

With ongoing trends in the food packaging industry, including batch-of-one operations, Industry 4.0 and the digitisation of manufacturing, there is now a demand for production flexibility and improved product traceability. Environmental sustainability is now also highly demanded from consumers, brand owners, governments and non-government organizations (NGOs), where products with a reduced environmental burden are required. Digital printing techniques are seen as a cost-effective way of printing variable data and product branding and, as such, are displacing traditional printing methods. Inkjet printing is the technology used universally to print images and text on a range of absorbent media (including food packaging). Solvent based ink formulations, commonly used in the printing of identification marks, have good durability and dry quickly due to the presence of volatile organic compounds (VOCs). As VOCs are hazardous to both health and the environment, there is a market desire to transition away from their use. Aqueous based inks involve the use of water, which is readily available and non-harmful to the environment. However, there are additional problems to overcome when dealing with water-based inks including drying time, durability (without the use of primers and varnishes) and adherence to specific (hydrophobic) materials.

From this it can be established that there is a pressing need for a VOC-free inkjet formulations suitable for printing onto food packaging, which combines the robustness and fast drying properties of UV and solvent inks with the environmental credentials of aqueous technologies. This project will address this need by developing novel, curable materials which can be deposited from water. It will build on a previous collaboration between Domino Printing Sciences and Aston to develop a new UV-curable polymer technology platform. This recent research has unveiled the use of reversible addition-fragmentation chain transfer (RAFT) polymerisation to create block copolymers with the desired amphiphilic characteristics. RAFT is a versatile and robust technique that allows for control over many other characteristics including molecular architecture, molar mass, mass dispersity and chain-end functionality. These synthesised polymer additives make a great addition to aqueous ink formulations, successfully enhancing their characteristics as well as enabling thermal crosslinking. Current research is to synthesise UV triggerable block copolymers, which would reduce the energy required for heating during the crosslinking process. This research project revolves around the next step of considering the contents of the ink formulation and the environmental damage it may cause. Using monomers in the polymerisation process that are readily available from our environment/renewable resources (e.g plant oils) rather than from petroleum would significantly further increase the sustainability of the aqueous ink formulations.

Ultimately, researching to create a new water-based ink formulation has the potential to make real-world impact; completely disregarding the use of harsh chemicals that contribute to the deterioration of our environment would revolutionise the world in which we live in.