UV curing with a LED lamp occurs exactly the same way as when using a standard mercury lamp. The ink, coating or adhesive when exposed to the UV lamp undergoes polymerization. The main difference between a standard mercury lamp, and a LED lamp is the wave lengths emitted from the lamps which are available for curing to take place. A standard lamp has a broad spectra of wavelengths which spread from UV-C through UV-B and UV-A and visible and infrared. This means that an ink or coating formulation can have a mixture of photoinitiators that cure over this range of wave lenghts.
Today’s commercial LED lamps for Narrow Web have a narrow wavelength range, with a peak around 385 - 395nm. Therefore the ink and coating technologies have been reformulated so that the reactivity and cure results meet printer requirements at this LED output. LED lamps also vary in irradiance output. In our industry, typical irradiance output is between 16 - 20 Watts/cm2. However lower irradiance outputs can be used successfully depending on application and speed, etc. Flint Group Narrow Web has close co-operation with all the leading suppliers of UV LED lamps, and we have tested and can verify that our EkoCure products cure exceptionally well with lamps from Phoseon, Air Motion System, GEW and IST. Qualification with other lamp manufactures is ongoing.