On the UV LED Wavelength

As a technology, LED (light emitting diodes) has already infiltrated our day to day lives to such a degree that we are all familiar with it in one form or another, be it in a torch, low energy lighting or car lighting. The advantages that LED technology offers in applications that we are familiar with, such as long lamp life and low running cost due to low power consumption, are fundamental attributes of LEDs that are available benefits for those in the printing industry working with energy cured inks. It is hardly surprising then that the industry is showing great interest in the technology.

To date, energy cured inks have typically been cross-linked (dried) by means of ultraviolet light emitted by low pressure mercury arc lamps or more exceptionally by means of EB (electron beam) technology, but it is also possible to cross-link energy cured inks by means of LED.

"The flexographic market can now benefit from UV LED curing technology with the introduction of higher power UV LED curing lamps."
Chad Taggard, Vice President of Marketing and Business Development, Phoseon Technology

LEDs are solid state devices (diodes) that emit energy in the form of light when an electrical current passes through them in the forward biased direction. The wavelength of the emitted light depends on the material from which the diode is made, with each material emitting light in a very narrow waveband that is almost monochromatic.

UV LED has a number of advantages to offer compared with conventional UV lamps, and these can be broadly grouped into environmental advantages, cost advantages and processing advantages, plus a few miscellaneous advantages.

The main environmental advantages are that LEDs are mercury free, do not produce ozone and consume less energy than medium pressure conventional UV lamps.

Economic advantages include lower energy consumption in their running state, and because LEDs switch on and off instantly, no warming up time is required.

UV LED curing is able to offer a number of cost, environmental and processing advantages over traditional medium pressure UV lamp systems and these potential benefits are generating a lot of interest in the technology from the printing industry in general. The technology has already made inroads into digital inkjet printing, where it is reported to have captured about one-third of the energy curable market and is now moving into screen printing. Growing confidence outside the flexo markets has encouraged an increasing number of printers and suppliers to investigate and develop its potential for flexo.

The view of Chad Taggard, vice president of marketing and business development at Phoseon, is very positive with regard to flexo. He commented, ‘The flexographic market can now benefit from UV LED curing technology with the introduction of higher power UV LED curing lamps. These lamps will enable smaller footprint flexo systems with simplified media paths and more varied substrate choices. End users will benefit with higher productivity, safer work environments, and reduced operating costs.