TRANSITIONING TO A SUSTAINABLE PRINTING ENVIRONMENT

The DG-AUXO web-offset press series with Electron Beam curing offers an opportunity for energy savings and sustainable print production
In the April issue of Converter Magazine, we  introduced DG press’ work and view on sustainable printing; explaining the main drivers why the DG-AUXO web-offset press series is potentially the most sustainable printing technology, and therefore the best alternative for solvent- and water-based printing technologies.

In this article we highlight the sustainability advantages of the DG-AUXO web-offset press series with EB curing for packaging printing applications.

Energy savings
The costs of energy is increasing, forcing flexible packaging printers and converters to consider their options and investigate energy-efficient alternatives. Especially  printing companies that utilize printing- and drying technologies with a high energy consumption.

VOC control technologies; like catalytic oxidizers, TOs and RTOs, have improved in energy efficiency, handling hot air without the need for additional fuel to start up or continuing the oxidation process. However, the total energy consumption is still much higher than what is required for printing processes utilizing energy curing.

In modern solvent-based operations, drying air is heated by thermal oil in order to create an indirect heating source, enabling the optimization of the (legal) threshold for Lowest Explosion Level (LEL).  That is a clever solution because optimized LEL enables the recirculation of drying air, thus reducing energy consumption and optimizing the solvent load to a RTO, hence improving autothermal afterburning. However, heating up the thermal oil and maintaining its operating temperature, requires a hot oil boiler plant. The boiler that is fed with natural gas, adds  to the total costs of energy consumption. Besides the cost aspect, sustainability aspects like reduction of GHG emissions are becoming more important, making printing technologies with a lower carbon footprint favorable.

Bio based solvents
As long as the use of significant amounts of solvents in liquid ink is required, it is questionable whether such printing technologies can ever become sufficiently sustainable. The same applies for bio-solvents that are being used at increasing amounts in solvent-based printing inks. Produced from renewable resources, like corn, sugar cane, or wheat, the production of bio-solvents is in competition with other agricultural land use such as food and feed production. And therefore, it encourages deforestation. The outlined situation makes it questionable whether the bio-solvent approach is truly sustainable.

Restrictions and Legislation
On the European governmental level the “EU council Directive 1999/13/EC” on solvent emissions, but also Germany’s “TA-Luft”, the Technical Instructions on Air Quality Control, set out tight emission limit values for VOCs in waste gasses and maximum levels for fugitive emissions.

New installations, or expansions of existing production utilizing solvent-based technology, must comply with the same strict requirements regarding max VOCs emission limits. Existing plants must administrate their solvent consumptions and emissions in order to check and prove compliance in accordance with the established goals and the prevailing regulations.

In the few cases where investments in solvent-based print capacity are still allowed, it is under strict conditions and limitations that can only be met at high costs, which makes the economics even more challenging.

Web-Offset
Regarding reduction of energy consumption and elimination of solvents the DG-AUXO with EB curing offers a sustainable and economic solution for both aspects.

Web-Offset with Electron Beam curing is the only technology that incorporates a number of advantages; from economical short-runs and high print quality, to being the most sustainable printing process.

Solvent free operation and low energy consumption leads to a low carbon footprint. Additionally, Web-Offset has a number of other important advantages that are appealing for most of the flexible packaging printers. Examples are the low-cost offset-plates and low-cost plate imaging process, which is also the fastest of all plate imaging and processing systems available.

Offset plates offer the highest possible print quality at only a fraction of the costs of gravure cylinders or flexo-plates. Imaging, processing and mounting of an average ECG job of 7 offset plates is fast and easy. In contrast to polymeric flexo plates, offset plates are fully recyclable and bring a good return on ‘scrap’ value.

The use of Extended Color Gamut, abbreviated as ECG, adds some major advantages to Web-Offset printing. ECG works with a fixed color palette in the press, eliminating the use of PMS colors and all the related drawbacks like cleaning, ink waste and logistics. This realizes savings in waste, time and money. The advanced web-tension control and accurate register control of the DG-AUXO make it ideally suited for ECG production even when printing stretch sensitive substrates. There are more advantages to ECG but those go beyond the scope of this article.

For true sustainable packaging printing; successful de-inking of the printed substrates is part of the game. In that view, de-inking of energy curable inks has been considered as more difficult. However, compared to solvent-based inks, energy cured ink particles have the advantage that they do not dissolve completely in the washing fluid. Therefore, they are easier to separate from the fluid, leaving a cleaner washing fluid for a continuous high quality de-inking process.

EB curing operations
And finally, a few words about operating an Electron Beam installation on a DG-AUXO. Although relatively unknown, EB curing on web-offset presses is a mature technology that has been commercially in use for decades. Unlike UV curing, EB curing works completely without photoinitiators, providing safe conditions for food packaging. Operating an EB system is safe and easy to control, as there is only radiation when the unit is switched on. Adequate shielding prevents any radiation from escaping the unit. As soon as the electricity is switched of, the radiation completely stops. EB systems do not create any residual radioactivity.

Operating an EB system does require authorization and annual check-ups by an official radiation body assigned by the national authorities. The energy consumption of an EB unit is relatively low in comparison to other ink drying technologies, and besides, EB operation does not release any environmentally harmful emissions. This makes it the most sustainable ink curing solution on a web-offset printing press.

The author Adelbert Schoonman is Senior Engineer for Development at DG press ServiceS and has over 25 years’ experience in the development of Web-Offset presses for packaging and label printing.

For more information contact DG press ServiceS BV in The Netherlands.
+31 313671911 / info@dgpress.nl