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Feb 1, 2011 12:00 AM
There's been a lot of talk about the potential advantages of LED curing technology on sheetfed presses. But don't mothball those UV lamps just yet, advises Bill Bonallo, vice president of IST America Corp.'s (Bolingbrook, IL) sheetfed group. “The complete replacement of conventional UV technology on a large scale seems improbable,” says Bonallo. “We think it will supplement conventional UV and may actually enhance it.”
IST is experimenting with “Instant Cured Commercial” (ICC): LED wavelength inks cured with conventional UV or modified arc lamp outputs. “It uses an LED-like ink with a modified conventional UV curing system,” Bonallo explains. “We've gotten phenomenal curing results with very few lamps. This a concept borne out of experimentation with LED reactive inks exposed to highly efficient conventional UV arc lamp technology.”
Long perfectors are a potential application. Whether it's an 8-unit, 4/4 press or a 12-unit, 6/6 model, these efficient presses are a curing challenge. “It's somewhat of a Holy Grail to cure that stuff without an interdeck lamp, all that heat and the all the marking related issues,” says Bonallo. “It would be great if you could run one UV lamp before the perfector and one at the end while still maintaining a reasonable amount of gloss with no concerns about conventional ink issues and no spray powder.”
Although ICC is still under development, Bonallo is optimistic: “It could put a real dent in the oil-based ink market for commercial printers. The challenge is all in the ink; the hardware side is pretty simple.”
But again, UV curing technology is far from obsolete. “It's a different world,” says Bonallo. “One is not going to replace the other. These modified LED inks and UV hardware will not replace the UV mainstay as we know it today. It will supplement it.”
UV LED is best suited for use on comparatively narrow printing units. Also, the curing unit must be as close as possible to the substrate. It's well suited for inkjet and narrow-web applications. LEDs are expensive and much lower in curing power vs. UV lamp output. LED's narrow wavelength window imposes tight parameters for inks and other coatings. There are relatively few LED-compatible materials (inks, coatings and subcomponents). There's also the potential price hurdle of replacing an entire LED array vs. a single conventional UV lamp. (See “LED & UV: a Sure Cure,” September 2010. Also: InFocus guest blog: “LED & UV Technology.”)
IST's new LED UV system (“LUV”), offers multiple wavelengths (365-395 nm) within the same array for maximum flexibility. The LUV unit is a cascadable system which enables LED modules to be arranged one behind the other at 70-mm intervals. Water cooling ensures uniform temperature management. System power can be regulated in one-percent increments from 0-100%.
New developments on the conventional UV side: IST's exclusive UV reflector geometry and multiple position shutters (closed, intermediate or wide) yield significant energy savings on its newly developed UV end-of-press sheetfed press curing system. Only two (200 W/cm each) individual plug-in modules are required (on certain system configurations). Unlike a conventional mecury discharge lamp, UV power is available immediately after the lamps are turned on. Individual modules can be activated or deactivated depending on the desired geometry of the illuminated area. E-mail: email@example.com.
Today, UV is ubiquitous among U.S. commercial printers, but that wasn't always the case. “UV really started out on the packaging side,” says Bonallo. “It was much more predominant in the United Kingdom. In the U.S. there was an elite group of printers doing boutique, high-end work, a lot of car brochures, annual reports and things like that.” Most of the UV pioneers ran large multicolor machines, 8 or more units plus coaters, an unheard of configuration. “George Rice and Anderson Litho really were groundbreaking — they were printing very high-end commercial work 40-inch printing press with full UV, with an interdeck between every print unit. They weren't the only ones, but they certainly set the standard, no question.” Most high-end commercial printers were chasing the same work. “That really brought UV much more into the mainstream than it was before,” he adds.