What's New in Coating?
Innovations in UV, LED and more for digital print, offset print, lithography and flexography
“We’ve had some customers invest in digital flexo imagers specifically for inline flexo units to create effects where certain parts of an image receive more varnish than others,” explained Ian Hole, VP of market development for Esko. “For example, imagine a tree in a field in front of a mountain range. Printers are varnishing just a bit of the tree, while keeping the mountains flat. They even limit the varnish depending upon the depth of the tree’s color – for example, 65 percent to 35 percent – for modulated leafing. It helps to make the tree [visually] ‘pop’ out of the page, creating added dimension.”
The arrival of hybrid inks, consisting of a photo-initiator mixed with conventional ink, is what really helped to put UV on the mainstream map. Thanks to ink raw materials advancements, the latest generation are a highly refined set of pure UV ink sets with no conventional components. Sometimes still referred to as “hybrid,” these UV inks are compatible with conventional rollers and chemistries, as plates, blankets, and washes have adapted and improved. Once relegated as a specialty, installing inline UV dryers is more of a necessity for sheetfed shops producing premium work these days.
Some four years ago, in time for drupa 2008, AMS adapted aspects of its Peak 3 UV curing lamp for web-offset use. With the appropriate number of water-cooled lamp units, it can scale up to 81-inch curing at 3,000 feet per minute. The P3 WebUV Curing System uses AMS’s Wide-Beam reflector geometry, which allows high-speed curing to take place at lower power settings – “debunking the myth that a narrow, focused band of UV is required to maximize the cure,” the firm said. What might show-goers see in Dusseldorf, Germany, at the quadrennial drupa mega show this May? Watch for more LED (light-emitting diode) systems, which are among the biggest, boldest “new” developments, predicted AMS CEO Metcalf.
Used in low-energy holiday lighting, LED lamps now see widespread use on inkjet printers to cure addressing or wide-format print. Dramatically more energy-efficient, they draw 70 percent less power during operation. Plus, the lack of heat generation and ozone emissions make them more environmentally sustainable. First seen in North America at PRINT 09 in Chicago, Ryobi commercially released an LED-UV version of its 31x23-inch 756G press model three years ago featuring Toyo FD LED inks for thin paper and 365-nanometer (nm) LED lamps from Panasonic. In mid-2011, Ryobi proclaimed that its LED-UV ink system slashes costs, provides super-quick turnaround, and allows offset to compete effectively with digital down to just 50 sheets.
KBA and Presstek are among the OEMs offering offline UV coating and curing extensions for their small-format presses. Heidelberg has its DryStar UV drying system. With advanced software, it is possible to save all dryer settings with a job and call them up again at the touch of a button. This feature can save a great deal of time, especially with complex dryer configurations, noted the manufacturer. AMS has worked with all the leading printing press manufacturers, including KBA, Komori, and Mitsubishi (MLP).
With these latest enhancements, “a printer can get into UV curing without some of the traditional hassles,” explained Metcalf. It extends the use of UV beyond the realm of specialists, such as folding carton, packaging, and label printers. There’s an ease of adoption now,” he continued. “It [UV-LED] really could go into a commercial print environment where solvent inks are being used.” After all, having something dry off the press is key, especially for short runs, he added.
Already making news last fall was the GRAPH EXPO debut of Grafix USA’s Green-UV, which delivers instant curing of LED inks and coatings using a pair of UV lamps specially tuned to the highly reactive inks’ wavelengths. As a cost-effective entry into UV technology, Green-UV opens up new lines of business for commercial print shops and package printers. It produces stunning glossy effects and excellent rub resistance, like conventional UV, while affording the environmental benefits of printing with LED inks. Two UV lamps rated at 300 watts/inch accommodate most process-color print jobs, including jobs printed with thick inks, running at normal press speeds. Located in the delivery of the press, the metal halide-doped lamps eliminate the need for interdeck UV lamps, as well as the standard three-lamp, end-of-press drying system. Sheets come off the press completely dry and ready for work-and-turn or immediate finishing.
