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UV LED Impacts Label Market

AS Labelexpo shapes up to be the show where LED makes its first major impact, Andy Thomas assesses the latest Phoseon lamp technology

Phoseon has been at the forefront of developments in UV LED technology, and its lamp units are to be found on several UV LED applications at Labelexpo Europe.

UV curing is a photopolymerization process that uses UV energy to change a liquid to a solid. Upon absorption of the UV energy, the photoinitiator (Pl) produces free radicals which initiate cross-linking with binders (monomers and oligomers) in a polymerization reaction to cure or solidify the ink.

UV LEDs are more environmentally friendly because, unlike arc lamps, they do not generate ozone and contain no mercury.

UV LED curing technology uses semiconductor-based light emitting diodes (LEDs) to project ultraviolet (UV) light when an electric current is passed through them. When a light-emitting diode is forward-biased,  electrons are able to recombine with electron holes within the device thus releasing energy in the form of photons.  The color of the light emitted or corresponding energy of the photon is determined by the energy gap of the semiconductor material.

The benefits of UV LED as compared to traditional mercury arc UV lamps are potentially significant for label printing applications. UV LED offers the ability to print on heat sensitive substrates not feasible with  traditional arc lamps without the use of chill drums. They are a cool source due to no output in the infra-red range and require no ducting. UV LED are more energy efficient than traditional arc lamps. 'The electrical to optical conversion efficiency of UV LEDs is much better, plus the instant on/off and no warm-up time results in a combined savings of up to 70 percent on electricity,' says Phoseon. UV LEDs are more environmentally friendly because, unlike arc lamps, they do not generate ozone and contain no mercury.

LED curing technology has advanced significantly in recent years and now offers enough power and capability to support 'conventional' label printing applications. The label industry continues to challenge and drive the ink formulation and chemical material suppliers with UV LED wavelength optimized materials. At the same time, UV LED curing units have become more efficient in delivering higher energy to the media, delivering increased throughput and process flexibility.