The ultraviolet/electron beam (UV/EB) market has seen long-term, sustained growth for many years.
Brand owners and their converter partners are aware of the associated benefits, namely, their productivity and potential for improved sustainability. And, with cost and the environment top-of-mind, brand owners and converters are turning to energy-curable technologies as part of the printing toolbox to power up their packaging performance.
All photos courtesy of Sun Chemical
Two things need to continue to happen to spur growth even further, particularly in the flexible packaging space, where phenomenal potential exists:
- Meeting regulatory and environmental requirements, such as low migration
- Further R&D
Energy-Curable Ink
The majority of energy-curable inks are materials that form free radical species when exposed to UV light or high-energy electrons. Reactive species then combine with other materials to form a polymer network. UV, UV LED and EB are three energy-curable technologies to highlight.
- UV printing is an evolved technology and offers fast curing with the energy required for faster presses. UV flexographic printing can handle more sensitive substrates, enabling them to produce low migration. Conventional UV printing can be utilized in a variety of markets, including cosmetics, wrap-around labels, shrink sleeves and more
- UV LED flexographic printing for food packaging is becoming more common because of its sustainability and low-migration strengths. Converters are seeing further environmental and application benefits of UV LED-cured technology, as it offers the largest volume and growth opportunities, due to the high productivity and performance advantages. From an energy standpoint, UV LED consumes less electricity and eliminates ozone production during printing, which is important to many users who are considering LED as an option
- EB inks represent another sustainable alternative for flexible packaging applications, as there are no volatile organic compounds (VOCs) or solvent recovery systems needed. EB flexographic printing facilitates various surface print options to help create alternatives to lamination—a strong benefit as new recyclable or compostable films are considered. New barrier coating technologies are sometimes used in conjunction
Curing Process
UV curing utilizes mercury lamps, which provide around 1,000 hours to 2,000 hours of usage and require a few minutes to warm up to reach curing temperatures of approximately 140 degrees Fahrenheit. The result is upwards of roughly 2,100 kilowatt hours per week of energy usage by a printer. As converters look for ways to improve efficiency and reduce energy costs, many have explored the option of switching from mercury lamps to LED curing lamps for energy benefits.
“EB curing provides instant results without the need for heat or evaporation and is compatible with high converting speeds.”
To cure an EB ink, voltage is supplied to a tungsten filament and a cloud of electrons is created in a vacuum. By utilizing repelling and attracting devices or accelerating grids, the electrons are directed to pass through a titanium foil window into a nitrogen-inerted environment—mostly free of oxygen. Nitrogen is continuously pumped into this curing zone to keep the oxygen level at less than 200 ppm.
A moving web of EB printed and/or coated paper or film passes through this curing chamber at press speeds between 900 fpm and 1,600 fpm. Then the beam of electrons helps initiate free radical polymerization of monomers and oligomers to instantly convert these liquids into solids. The degree of polymeric conversion is nearly complete at 99.99 percent.