Ultraviolet & Electron Beam (UV/EB) Flexography

Potential Advantages

Primary advantages of UV and EB ink technologies list out in three specific areas, namely, meeting regulatory requirements, focusing on sustainability and increasing operational efficiencies. Each is discussed here.

Meeting Regulatory Requirements

Since brand owners have the responsibility to ensure safe packaging and compliance with all regulations worldwide, focus on food safety is at an all-time high. It is incumbent upon brand owners to scrutinize their supply chain from all angles to minimize risk.

This applies to packaging as much as to product sourcing and preparation. Where food or sensitive cosmetic products are concerned, it is vital that brand owners work hand-in-hand with their partner converters to ensure the inks being used are suitable for the contents and pose no risk to consumers. Of the three types of energy-curing ink systems, EB offers the lowest ink and coating product costs, especially for low-migration applications. The EB curing method offers the lowest level of residual chemical migration of any other ink technology or converting technique, making EB technology a preferred option for food and sensitive packaging applications.

Sun Chemical Bishop Hemmings EnergyCurable WEB
A moving web of EB-printed and/or coated paper or film passes through the curing chamber at press speeds between 900 fpm and 1,600 fpm. Then, a beam of electrons helps initiate free radical polymerization of monomers and oligomers to instantly convert liquids into solids.

It should be stated that some regions, such as California and the European Union, are strict on specific energy-curable chemicals that can and can’t be used. This affects the costs of energy-curable materials.

Additionally, UV LED printing offers low odor and migration properties, plus it is designed for folding carton and flexible film packaging applications, where high press performance, color vibrancy and regulatory compliance are critical.

Focusing on Sustainability

As sustainability and safety continue to challenge converters to partner with responsible ink manufacturers, UV inks and EB printing offer sustainable solutions that many printers believe will achieve their goals.

It’s important to note that UV lamps contain mercury bulbs, which is a concern for some printers due to the cost of disposal and environmental considerations. Additionally, with conventional UV lamps, printers face the challenge that ozone is created around the mercury lamps, which generally requires installation of exhaust systems.

By switching to LED lamps, converters can eliminate the need for exhaust, have a longer lifespan, avoid heavy metals like mercury, and enjoy a more consistent UV output over the operating life of the lamps. According to an energy efficiency study by Fogra, LED curing showed energy reductions of up to 82 percent, with a savings of approximately $18,000 per year. LED lamps are extraordinarily energy efficient, reaching a maximum of 104 degrees Fahrenheit instantaneously without any startup delays.

Protective cross-linked EB coatings can greatly reduce waste for printers looking to achieve sustainability goals in an economic and cost-efficient way, as they offer one way to replace laminate or extruded film layers and completely avoid the lamination step with adhesive, curing and storage time. This can also contribute to light-weighting of the package.

VOCs are also a major concern for the industry. Brand owners and converter partners are aiming to emit little-to-no VOCs in their processes because when a printer offers low VOC, it significantly reduces the carbon footprint of a business. Energy-curable ink chemistries are beginning to include biorenewable and recycled raw materials, based on modified resin developments and also on available post-consumer recycled plastics. Energy-curable inks are considered zero VOC or 100 percent solids, thus diminishing the discussion around emissions.

De-inking a substrate enables a package to be recycled, rather than downcycled, helping to contribute to a circular economy. If the ink is not removed from a substrate, it downgrades the possible application potential in the recycling or composting process. However, when the ink is removed, it may contribute to a true cradle-to-cradle approach.

“…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.”

While de-inking for paper and carton board is already a well-established procedure to truly recycle paper in the cradle-to-cradle approach, EB coatings can help eliminate the secondary web, reducing waste and adding the potential for much easier plastic de-inking properties as compared to laminate packaging.

Increasing Operational Efficiency

The EB curing process offers converters a solution without solvents or photoinitiators, while providing outstanding organoleptic and migration compliance (60 degrees). EB flexography provides very similar print resolution results when compared to the use of water- or solvent-based flexographic inks.

The EB curing method is a cold-curing technology. EB is both heat and solvent resistant, increasing the durability of the printing. However, that does not impact how quickly the curing occurs. EB curing provides instant results without the need for heat or evaporation and is compatible with high converting speeds.

Additionally, EB produces results with a relatively small footprint compared to traditional drying ovens. Overall, it is energy efficient and delivers the effects at nearly room temperature, so it is compatible with temperature-sensitive films, thin films and heat-shrink materials. EB inks and coatings allow for high-temperature heat sealing and retortability, providing a great opportunity for package recyclability.

Conventional UV and LED have the added benefit of curing products fast, thanks to greater curing efficiency resulting in less distortion of the substrate.

Bright Future

Brand owners and their industry partners are constantly looking for sustainable, high-performing solutions, and as R&D continues in the energy-curable space, the technology will continue to expand, bringing more to the table than ever before.

The future of UV/EB is undoubtedly bright. With the various benefits the technology offers, the market will continue growing exponentially, as it has for several years.

About the Authors

headshot Derrick Hemmings
Derrick Hemmings is the product manager of energy-curable products for flexo, North America, at Sun Chemical. For information on Sun Chemical’s UV/EB offerings, call 708-236-3798 or email [email protected].
headshot Jim Bishop
Jim Bishop is the field product manager of UV, EB and conventional packaging products at Sun Chemical. For information on Sun Chemical’s UV/EB offerings, call 708-236-3798 or email [email protected].