Coil coating is a continuous automated process for pre-painting metal like steel and aluminum before its formed into end-use products like garage doors, gutters, roofing and parts used in appliance, automotive and industrial applications. It is one of the most widely used paint application methods for metal.
In the process, metal coils are unwound, cleaned and pretreated, then painted, cured and cooled. The metal sheets can then be recoiled and shipped to a fabricator or manufacturer.
Two factors are critical for optimal coil coating durability and aesthetics: paint formulations made with quality pigments, resins and additives and proper curing that enables the liquid coating to harden and form a solid, protective finish.
Most conventional coatings cure with heat from thermal ovens or air drying for hours, but newer technologies use radiant energy sources from ultra-violet (UV) light or electron beams (EB) to initiate the curing, or crosslinking, process.
Known as energy- or radiant energy-curable coatings, these solutions fully cure at room temperature in seconds or less, eliminating the need for thermal ovens or cool down time.
While energy-curable coatings have been used for more than 50 years primarily on wood products like flooring, recent advancements are bringing the energy-efficiency, sustainability and productivity advantages to coil coaters.
Energy Efficiency & Reduced Carbon Footprint
Ongoing regulatory efforts to restrict or eliminate volatile organic compound (VOC) emissions are helping to raise interest in energy-cure formulations as they are made with 100% solids that are free of solvents that release VOCs, helping manufacturers reduce their carbon footprints.
But energy-efficiency is also contributing to the growth in UV/EB coatings as the energy needed to power UV lamps and electron beam devices is significantly lower than what is required for conventional thermal drying ovens. In fact, the energy usage and savings can be significant.
Faster Production Times
Without the need to preheat, bake and cool parts, finishing speeds are must faster, creating higher product volume in less time.
In fact, UV-EB technologies cure in milliseconds with immediate conversion rates that are very high (more than 90%). Coils can be handled almost immediately for packing, storage and shipping, which also reduces the need for floor space to hold inventory at various stages of the finishing process.
Because energy-cure coatings are made with 100% solid content without solvents or water that evaporate during the cure, they maintain nearly the same film thickness before and after the cure, with virtually no loss in weight, so fewer coats are needed for full coverage. The result is real savings in time, material and waste.
PPG was among the first to offer UV-curable solutions for the wood industry with products like PPG CLARITAGE™ anti scratch UV topcoat and today remains a global leader in energy-curable solutions.
The newest products in the PPG energy-cure portfolio is the PPG DURANEXT™ UV/EB family of primers, backers, topcoats and clearcoats. This is the company’s first radiant-energy curable solutions for metal.
