Many corrugated converters seeking to invest in new printing equipment are weighing up the long-term advantages and disadvantages of choosing aqueous versus UV inkjet technology.
Natasha Jeremic, Head of Piezo Inks, Domino Printing Sciences, explores the performance of aqueous and UV inks, as well as the benefits of aqueous and UV printing technologies for corrugated substrates.
Key factors that influence ink durability and quality
There are various factors that affect ink performance in terms of durability, print quality, and sustainability, with ink formulation, substrate type, and curing or drying method all having a significant impact.
Benefits of UV ink in corrugated printing
UV ink technology has become a preferred choice for many print applications because of its exceptional durability and versatility. A photo-reactive curing process exposes the printed inks to ultraviolet light, triggering an instant chemical reaction called ‘polymerisation’.
This polymerisation creates a strong bond with the substrate, ensuring a smudge-free print with a resilient finish resistant to fading, weathering, chemical exposure, and mechanical damage. This attribute makes UV inks a preferred choice when printing on semi-porous and non-porous corrugated boards, with accurate control of ink drop size and shape an important contributor to achieving optimum print quality.
How does aqueous inkjet printing work for corrugated substrates?
Though often thought to be composed predominantly of water, aqueous inks for corrugated packaging can contain equal or greater proportions of other organic solvents. Unlike UV-curable inks, where polymerisation is triggered by UV light, drying of water-based inks relies on substrate absorption and evaporation. Depending on an ink’s formulation, very powerful, energy-intensive IR (infrared) driers or ovens are needed to ensure efficient drying, with lower drying times.
It’s important to note that the heat applied in the drying process of aqueous inks can have adverse effects on the substrate. Depending on thickness and fluting, corrugated board might warp or curl – an effect that becomes more noticeable when producing large, high coverage prints requiring longer heat exposure. Converters should be aware of this when evaluating an aqueous inkjet printing process, as drying efficiency can vary greatly. A fast-drying ink with an efficient, shorter drying process will limit heat exposure and thus the negative side effects for the substrate, as well as deliver reduced energy consumption, saving money.
How to speed up the drying of water-based inks on corrugated?
Accelerating the drying process for water-based inks on corrugated may require additional drying modules, which will need more factory floor space. To achieve a comparable laydown, surface coverage, and speed for aqueous ink, energy usage could be up to three times greater than usage in LED UV curing.
The latest generation of aqueous inks, such as the fast-drying Domino AQ95 ink set used by Domino’s X630i corrugated press, is specifically formulated to absorb and bond well with the surface of uncoated corrugated boards, reducing drying times and energy use. Film-forming polymer particles encapsulate pigment, enhancing colour fastness and durability.
Considering all this, which is the right choice for corrugated converters?
The answer very much comes down to the requirements of their brand customers and end-user applications. Converters should consider printing speeds, print quality, and durability, as well as choice of substrate when identifying which technology will be the best option for their needs.
Aqueous ink is a great fit for porous, corrugated board, but it is important to take a close look at the drying properties of the inks, as well as the drying technology used. Drying efficiency for aqueous inks and the energy consumption of their printing processes can vary greatly. In addition to delivering potential energy savings, some aqueous inks are able to produce high-quality, durable print results, without the use of primer and varnishes, improving recyclability and making them a more sustainable choice.
New aqueous and UV ink technologies have transformed the printing landscape, offering enhanced performance and sustainability across various applications. As advancements continue, these positions are bound to evolve further, but – for the time being – both play a vital role in meeting the diverse needs of modern printing applications.
Partnering with an experienced ink and digital printing provider can help converters choose the right solution for their needs.