UV LED Lamp Systems in UV Curable Industrial Applications: Achievements and Challenges
Dawn Skinner | Heraeus Noblelight, Germany
UV curing, using medium pressure Hg lamps, is a proven technology in a diverse range of manufacturing processes. It is an integral part of printing and wood coating through to applications in coating industrial plastic components, bonding and coating applications in medical devices, glass decorating, composite manufacturing, protective coatings for optical fibres and specialised coatings on flexible films, just as examples. All benefiting from the enhanced coating performance, fast cure speed, compact installations and the potential for 100% solids coatings and adhesives.
Advances in UV LED lamp technology and developments in formulations have led to the replacement of Hg based, broad-band emission UV lamps by UV LED lamps in several applications e.g. in some printing applications, wood coatings and adhesives. This adoption has been driven by several factors including, the process efficiency of instant on/off, minimal heat transfer to the substrate, and environmental aspects such as no mercury and lack of ozone production. However, some challenges still remain before UV LED curing can be used in all the existing UV curing applications.
Currently, the UV LED lamp systems used in industrial curing applications have emissions in the UVA range, typically 365, 385 or 395nm. This was driven by the need for high output power combined with long life-times and commercially acceptable costs of the UV LED lamp system. The lack of short wavelength emission leads to challenges in overcoming oxygen inhibition and achieving the good surface cure that many industrial processes require.
This tutorial will introduce the principle of the UV curing process, review the successes of UV LED lamps in current applications and the challenges and prospects for future successes. It will also include an overview of the latest developments in UV LED lamp design to maximise the efficiency in terms of power output and optics to improve performance at increased working distances.