Water, water everywhere in every drop of ink…

Dr. Simon Daplyn, Sun Chemical

Water-based digital inks are gaining traction in the packaging industry due to their perceived environmental benefits, improved performance, and growing demand for sustainable and safe solutions. These attributes are particularly important in food packaging where stringent regulations and standards dictate the solutions that can be used.  At drupa in May, it was striking how many new platforms showcased aqueous inks, even in markets previously dominated by UV inks. 

What are the reasons for this and why has it taken so long for water-based inks to make an impact?

First off, it is important to acknowledge that while several markets have been relatively stagnant in recent years, certainly since the pandemic, packaging markets have been extremely resilient and have experienced growth, especially in digital print applications. Despite the inevitable impacts of rising energy prices, increased cost of living, and global macroeconomic uncertainty, packaging continues to be strongly influenced by food markets. In contrast to other sectors like fashion, which have seen consumer cutbacks, food packaging has not been significantly impacted. Additionally, the continued rise of e-commerce and online shopping has meant the need for packaging has increased with a higher focus than ever on differentiated print and branding. Today, packaging plays a crucial role in the consumer brand experience where the pack received matches the online version.

The time taken for water-based technology to be adopted on a more industrial scale is in large part due to some of the challenges faced in formulating and adopting the technology.  Some of the key challenges faced when implementing water-based inks are:

Substrate Compatibility:

• Water-based inks may not be compatible with all types of substrates. Some materials, especially non-absorbent or coated surfaces, can pose challenges for ink adhesion, image quality and drying

• Ensuring that water-based inks work effectively on a wide range of packaging materials is crucial and can be managed with the use of a tuned primer to give a consistent surface for printing

Drying Time and Speed:

• Water-based inks typically require longer drying times compared to solvent-based or UV-curable inks. This can impact production speed and efficiency

• Balancing print speed with ink drying time is essential to maintain productivity

Print Durability and Resistance:

• Water-based inks may be less durable than UV-curable inks on certain substrates unless inks are carefully formulated with binders that can achieve the stringent requirements of the packaging industry

Cost Considerations:

• There has long been a perception that digital inks and in particular water-based solutions are expensive, however aqueous inks can be cost-effective in terms implementation, process and manufacture

• Balancing cost-effectiveness with performance is essential for successful adoption

Education and Training:

• Print operators and converters need training to handle water-based inks effectively. Understanding ink properties, equipment adjustments, and maintenance procedures is essential.  This is particularly relevant with printhead maintenance and print reliability as water-based inks can take more management that UV alternatives

Regulatory Compliance:

• Compliance with regulations related to ink ingredients, safety, and emissions is essential. Different regions have varying requirements and standards such as Swiss Ordinance which may not include newer resin technology so extensive testing may be required to prove suitability for a specific market segment

• Ink manufacturers, converters, and brand owners, must navigate regulatory complexities to ensure their products meet industry standards 

So why the apparent sudden rise of water-based technology?

Most digital ink developers have been working on aqueous solutions for many years often in complex projects with OEM partners and suppliers. Key advances in pigment dispersions and inkjet grade resins designed for packaging substrates have expanded the toolbox to afford water-based inks that can deliver results meeting end users’ requirements. There has also been a strong market pull for water based digital solutions across markets and particularly in packaging. The  reasons for this include:

Re-classification of some UV materials:

Several recent regulatory changes restricting the use of some key materials used in UV inks prompted converters and brands to consider alternative options.  Many of these can be re-formulated to maintain the same quality however it may create aqueous options

Substrate evolution:

To comply with recycling regulation, there has been a shift in substrates, including efforts to increase recycled content. In flexible packaging, for example, there is a movement towards mono-material films, which eliminates the use of metallised barrier layers or laminated multi-material films and so aqueous inks are favoured for lower/no migration and reduced set-off risk.

Corporate Social Responsibility and Sustainability Goals:

There is a strong perception that water-based technology is more environmentally friendly and can incorporate a higher level of renewable materials, reducing the environmental impact of the ink.  It should be noted that life cycle analyses are required to determine if a replacement ink provides a quantifiable environmental benefit. 

De-inking Potential:

In general, aqueous inks were considered easier to de-ink from a range of substrates as they typically require milder detergents in the process. However, bleed into waste water and decolouration of recycled material is a high concern.  Newer technologies are being developed to address these concerns.

Collaboration:

The digital print OEMs, ink manufacturers and software and electronics manufacturers have been working closely to develop end-to-end solutions that meet the full list of requirements for the different segments within the packaging market. This has led to multiple innovations and the reimagining of previously discussed technologies, such as inkjet-flexo hybrid presses, in-line nozzle inspection, nozzle compensation software, waveform developments and drying combinations. These innovations enable high speed, reliable and consistent printing while delivering all of the known benefits of digital print for a dynamic market requiring increasingly shorter run lengths and lead times.

With this market pull, each key segment within the packaging market is embracing new aqueous ink developments alongside the significant strides made in hardware and software to ensure consistent and reliable printing on an industrial scale.

Segments Embracing Water-Based Inks

Flexible Packaging

Flexible packaging, once a challenge for water-based inks, is now viable. Brands are increasingly using mono-materials for recyclability, and water-based inks play a crucial role. Recent innovations in ink technology have improved the print quality, drying speed and resistance properties. In many cases a digital ink with an associated primer can now deliver outstanding prints onto a range of filmic substrates. This trend was evident at drupa with multiple new platforms for digital printing of flexible packaging, all demonstrating water-based inks

Corrugated Packaging

Corrugated packaging is also adopting water-based digital inks. Innovations in aqueous ink formulations are driving adoption as digital printers aim to provide versatility across coated and uncoated board for diverse applications including shipping boxes and consumer goods packaging.

Folding Cartons

Folding carton printing is gaining momentum, particularly in food packaging. Given the widespread use of cartons in this sector, water-based solutions that meet stringent compliance requirements are emerging as a preferred choice.

Labels and Narrow Web Printing

Inkjet printing, particularly in label production, has become well-established. UV LED inks and systems deliver exceptional quality in this segment with water-based inks starting to penetrate for certain label stocks.

Conclusion

The adoption of water-based digital inks is on the rise across packaging segments. As the industry continues to prioritise sustainability, both in terms of the chemistry and substrate requirements, water-based inks play a vital role in meeting brand demands and consumer pressure to improve environmental standards.  Look out for new solutions and for the industry to continue riding the wave of success brought by aqueous technology.