Consumables
RW Coatings has developed a varnish range suitable for LED-UV lamps
Thursday 06. May 2010 - At Ipex 2010 in Birmingham (18th - 25th May), RW Coatings Ltd will presents its brand new varnish range cured using LED-UV technology. Along with other benefits, this pioneering technology offers significant energy savings (60% and more) and eliminates the need for air exhaustion since no ozone is generated any more during the drying process.
RW Coatings is one of the world’s first coatings manufacturers to develop the special varnish needed for the latest UV technology. This pioneering achievement involved developing UV overprint varnishes for the highly specific radiation spectrum of LED-UV light that cure fully despite the low energy and are a match for conventional UV varnishes in terms of drying speed.
During beta tests using suitable equipment, print speeds in excess of 20 m/min were achieved, with the varnishes curing flawlessly. This innovative use of LED-UV drying technology was developed by Nordson UV Ltd.
John Russell, Technical Director at RW Coatings, said: “The application of this UV-LED drying system which has been successfully developed with our partnersÂ’ shows that sustainability and innovation can go very well together.” LEDs (light-emitting diodes) are based on the principle of electroluminescence: a tiny semiconductor panel emits light when subjected to an electric current. This light consumes very little energy, the diodes have an extremely long working life and they generate no ozone. With similar applications to conventional UV lamps with mercury tubes, the LED-UV lamps which can be built into new presses or retro-fitted, they consist of innumerable small LED panels arranged across the entire width in multiple rows.
In particular the Nordson UVED unit which will be demonstrated on the RW Coatings booth at Ipex, Hall 7 Stand C479 will be of particular interest to manufacturers of digital presses and off-line coaters. Up to 32 individual LED-UV modules can simple be joining together to form a curing strip of 1984mm.
The print path is routed close to the LED panels since very little direct heat is generated. While a conventional UV lamp requires a warm-up phase lasting a few minutes, the LED-UV lamp has no waiting time and is immediately operational after switch-on.
The LED-UV lamp emits only a small range of the conventional spectrum of UV lamps. In particular, the high-energy IR radiation and the hazardous UV-B and UV-C radiation are absent. Due to the extremely narrow wavelength window of the LED-UV lamp (peak at 395 nm), conventional UV varnishes cannot be dried using the new lamp. This makes the new varnish range developed by RW Coatings indispensable for the LED-UV technology.
As with every innovation, the lamps and varnishes are currently still somewhat more expensive than those for conventional UV drying. The additional cost amounts to about 15% to 20% for the varnishes. However, the much lower energy consumption (savings of 60% to 80%), the elimination of air exhaustion systems and the greater work safety are powerful arguments that are all clearly in favour of the new LED-UV technology.