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More sustainable curing technology for coil coatings

| By Gerald Ondrey

Coil coating is a continuous process for producing prepainted sheets of metal (steel or aluminum), which can then be fabricated into various building and other materials. Because organic coating materials are used, the process requires substantial energy for the curing and drying steps, and can generate significant emissions of volatile organic compounds (VOCs). To make the curing process more sustainable,there are efforts to find alternatives to traditional thermal-curing processes (diagram, left). The European Coil Coating Assn. (ECCA; Brussels, Belgium; prepaintedmetal.eu) considers ultraviolet (UV) and electron-beam (EB) curing technology to be the most significant game changer in terms of decarbonization of the coil coating industry.

Now, Wilh. Beckers Holding GmbH (Berlin, Germany; www.beckers-group.com) has developed the first commercial paint formulations for dual UV and EB curing (diagram, below). Until now, the only available industrial application of radiation curing in coil coating has been EB irradiation used for packaging material. Long-term collaboration between Beckers and one of its customers has led to the first ever full-scale application of advanced, dual-UV/EB-curing technology in coil coating for the building industry.

curing technology

At Beckers’ development laboratory in Montbrison, France, a team of researchers has demonstrated that UV/EB curing has significant potential to reduce the CO2 footprint of coil coating, due to the fact that it requires much less paint and energy in the curing process. “UV/EB curing allows us to use up to 100% solid, solvent-free formulations that are more efficient and provide up to twice the surface coverage per kilogram of paint,” says Gavin Bown, CTO at Beckers. Solid, solvent-free UV/EB paint formulations are more sustainable, because around half the volume of paint is needed and they significantly reduce VOCs. “Compared with conventional gas-fired curing, the UV/EB cold-curing process also uses much less energy, facilitates the transition from natural gas to renewable electricity, avoids the use of expensive gas, and does not require water for cooling,” says Bown. Because the UV/EB curing process is almost instantaneous, coating lines can be shorter and run at higher speeds.