What's New in Coating?

Coatings can provide the visual appeal, lasting durability, protection, and rub-resistant finish that customers have come to expect from the printed medium – especially for end uses such as direct mail and frequent handling. Print firms are constantly trying to control coating costs and, ideally, bring outsourced services such as ultraviolet (UV) coating in house to increase profit margins.

Attendees at GRAPH EXPO last September saw one coating innovation, as Scodix unveiled the 1200 UV, a press that applies clear polymer on selective areas with variable densities and gloss levels. Employing 99 glossing units, the device creates the highest gloss available for printed materials: up to 70 microns in polymer height – which is 10 times higher than spot varnish. Gloss density can be set to variable capabilities, from 1 percent to 100 percent, allowing for easy single- or dual-sided printing. (Printed substrates are run under a UV bulb for instantaneous curing.) “Turning printing into an experience is the only way to survive theses days,” president Dror Danai said at the firm’s first-ever press conference.

Tom O’Brien and Lindsay Gray, co-owners of commercial printer Acculink, Greenville, NC, are believers. The pair bought a Scodix 1200 UV press at the show. “There just isn’t any other piece of equipment that can do what it does,” O’Brien told the official Show Daily publication. Not only is Acculink offering the special-effects printing to its own customers, but the QP Top 100 printer also plans to outsource the unique service to other printing companies.

Digital press OEMs with perhaps more familiar names chime in on the coating topic, too. HP offers its own near-line unit, called the Indigo UV coater, to protect its liquid ElectroInk output. For offline, near-line, and inline coating, Xerox contends that wetting performance is key for its toner-based prints. It recommends storing iGen 3/4 printed output for at least 30 minutes before offline coating but added that running fluids that are “qualified/developed for inline use with Xerox digital presses can eliminate this duration,” in its Finishing Hints and Tips Guide. “Most commercially available fluids are not optimized for proper wetting. They may also interact with the fuser agent on the sheets, causing coating integrity or appearance defects.”

Xerox noted that if the finished piece is subjected to cycles of high (≥ 140°F/284°F) to low temperatures, the coating may crack. Paper type does affect performance, of course, with coated, glossy stocks at weights above 140 gsm typically providing the best results. (iGen3 output sheets of basis weight 115 to 120 gsm have been UV coated.) Also, to minimize cracking, book cover applications require creasing at the folds after coating. “Uncoated stocks tend to absorb the coating material and thus not cure completely,” the manual advised. Plus, the plate or roller used to apply the coating may warp lighter weight stocks.

Caution aside, independent manufacturers play in the coating game, too. “The demand for UV coating has intensified in the past decade, especially in the digital environment,” said Tom Hayes, president of Kompac Technologies. Its Kwik Finish series offers 20-, 26-, and 32-inch sizes. Now distributed by xpedx, these are a convenient way to apply spot UV, aqueous, primer, and specialty coatings to a variety of substrates, from thin onion skin to plastics, says the manufacturer. With a smaller, 18-inch sheet size, the X7000 Series Smart Coater from Al’s Co. UV (Chino, CA) is another indie example. The offline system is compatible with Canon, HP, Kodak, Konica Minolta, Ricoh, and Xerox digital devices as well as sheetfed-offset machines from Heidelberg and Ryobi and Presstek direct-imaging (DI) presses. Late last year, TEC Lighting also launched the XB18 UV coater, an 18-inch coater engineered to interface inline with a digital press. Double-sided coatings can be varied, allowing, for example, a satin coating on one side of the sheet and gloss on the reverse side.

Olec’s modular Coat Master Series UV Roller Coaters produce high-quality UV gloss, matte, and satin finishes on a variety of printed stocks including screen, digital, and thin stock. Within its Gen II series UV curing system, sensors are placed before and after the UV tunnel for sheet-jam detection. The UV lamp automatically powers off if a sheet enters yet is not detected exiting the UV curing tunnel. A state-of-the-art cooling system uses a heavy-duty blower to blow fresh air onto the lamp reflector housing. Hot air is then carried to the exhaust system, where it is released.

This past June, Kompac released the latest in its EZ Koat line: the EZ Koat 15. It is a small-footprint, high-powered UV and aqueous coater capable of coating a sheet size of 14.5 inches wide by virtually any length. EZ Koat is the only UV coating system to feature solid state UV, which replaces outdated and potentially hazardous ballast/mercury relay systems. Kompac’s patent-pending, rotating UV reflector technology prevents over-curing when the coating process is interrupted. And its proprietary Vac facilitates coating changes and clean up in under five minutes.

EZ Koat 15 is designed for both digital and offset output, which does not surprise Steve Metcalf, president/CEO of Air Motion Systems (AMS), a leading manufacturer of high-performance conventional UV and UV
LED curing systems technology. “There’s so much cross-over now” between the conventional offset, flexo, and digital print processes, “from chemistry lessons to light-curing techniques,” he said. AMS is a founding and producing sponsor of the Print UV Conference (see box).

Game-changing dimension

Despite Kodak’s financial troubles, its NexPress continues to raise eyebrows with dimensional printing effects from its Fifth Imaging Unit Solution option. One of the most recent installations of the NexPress SX3300 Digital Production Color Platform, announced last December, is at commercial printer Image World in the Philippines. The SX Platform can print on more than 700 standard offset substrates, including coated, uncoated, FSC, plastics, magnets, linens, static clings, and microperforated substrates.

The Fifth Imaging Unit Solution was the defining factor in Image World’s purchase, according to Robert Sy, PhD and the firm’s chairman. “The most striking feature of the NexPress SX3300 Press is the Fifth Imaging Unit Solution, which can do at least six special tasks,” Sy explained. “The dimensional raised printing that actually makes the desired section of the image palpable and gives depth to the printed material; the watermarking that can be employed to make it look like the design of the paper; the glossing, whether full or spot, that stands out very clearly and definitely shines better than lamination; the MICR that has all the capabilities to print bank checks; red fluorescing ink that can print security and barcodes visible only under UV light; and the RGB that enhances colors and makes the brand color of each company possible.”

Dr. Sy foresees the potential for bringing new value-added products – such as photo books with dimensional effects and school diplomas with red fluorescing ink for added security – to his company’s repertoire. Unique in the industry for inline digital cut-sheet presses, dimensional printing is achieved by adding Kodak Dimensional Clear Dry Ink to the Fifth Imaging Unit of a NexPress. Characteristics previously unattainable with digital printing, such as a 3D tactile photo surface, dimensional, or raised print, and distinctive textures, have been incorporated into the design of NexPress-printed materials for the past four years.

Inkjet, too

There have been enhancements to high-speed inkjet coating technologies as well. HP, Kodak, and Océ are working with leading coated paper manufacturers to expand the range of coated stock choices for their production class inkjet presses. Last year, Sappi began deploying its new line of papers, including coated, specially designed for the needs of full-color inkjet printing.

Many firms, including direct mail printer Fenske Media Corp., Rapid City, SD, are using pretreated glossy paper to expand their substrate options. One stock the Fenskes run is NewPage TrueJet, another recently released coated papers designed for high-speed inkjet output. As previously reported by MyPrintResource.com (www.myprintresource.com/article/10597806/digital-print-visionaries), Fenske Media soon will add Kodak’s pretreatment module, branded the Inline Optimization Station (IOS), to its Prosper 5000XL color inkjet web press. The system is built around a roll coating technology that uses water-based pretreatment fluids containing adhesion-promoting additives customized to specific paper stocks with different chemistries, viscosities, and coat weights. Pretreatment can be applied to a variety of surfaces, including coated or uncoated, matte, silk, or glossy. Presently on order, when the IOS arrives it will “give Fenske the flexibility to run a broader range of stocks, particularly some additional coated ones that they would like use,” noted Jim Hamilton of InfoTrends. In addition, the Fenske brothers are tweaking an offline/near-line UV coater originally installed last May.

UV-LED matures

“In the LED [light-emitting diode] world, a lot of the lessons are coming from digital,” AMS’s Metcalf continued, “just like coating [technologies] from offset are coming to digital.” There’s a lot of give and take: from UV coatings and inks (see sidebar) to the application of light sources, such as LED, which Metcalf said is the number-one new technology at his firm over the past several years. “We had a breakthrough year in 2011,” he noted, citing several patent-pending new products. “LED is at the forefront of competitive [print] technologies,” he added. “It’s quite bold.” (More on that later.)

While there was some light buzz about UV-LED fledgling technology at drupa four years ago, visitors to the Dusseldorf fairgrounds this year can expect some major noise in the form of energy-efficient light waves. UV-LED curing pretty much began with digital printing and narrow-web inkjet at Drupa 08, Metcalf acknowledged. “But now the power and intensity is high enough,” he said, “so I’m really excited for Drupa 2012.” Traditional UV curing systems market leaders, such as AMS, Baldwin Technology, Eltosch/Dr. Honle, Grafix USA, IST Metz, Nordson, and PRI Technologies, have adopted UV LED lamps, which do not use conventional mercury gas. And LED’s reach extends well beyond the printing industry.

According to the Reportlinker search engine, UV-LED business is expected to grow from $25 million to more than $100 million in 2016 at a growth rate of more than 30 percent.

More than 90 percent of the UV-LED market (outside of R&D) is covered by UV curing, counterfeit detection, medical, and instrumentation applications requiring UV A/B sources. UVA (400 nm to 315 nm light wavelength) business is currently the main UV-LED market and will remain so for at least the next five years, thanks to a boom in UV curing. Other key UVA applications are document/banknote verification and photocatalyst air purifiers. (See factoid, below.)

The most dynamic and important UVA lamp market is clearly the UV curing business, where UV-LED competes with traditional mercury lamps. The size of the market is large: $120 million with growth of about 10 percent. Also, the power output available doubled between 2009 and 2011, reaching 16 W/cm2, and the emission source width is now up to 2 m, comparable to mercury lamp performance.

Litho Overprinting on Digital

Last July, ink supplier Kustom Group (Richwood, KY) introduced coating and overprint chemistries for digital printing. All too often the industry has focused on UV coatings as the product of choice to protect digital printouts, said Kustom, but there are other options that can satisfy the needs for many print jobs. For most printers today who have both sheetfed offset and digital press equipment on their shop floors, the use of a conventional litho press is not often considered—yet it can be used. Purchasing new UV coating equipment and learning about UV may not be necessary, depending on the application.

Kentucky Shine (KS-190 OPV) is a water-based overprint that has all the properties of a typical aqueous coating when applied over digital printing. It is easily applied by a dry offset process through the ink unit of any offset press. Matte, satin, and soft-feel finishes are available. Meanwhile, Lithomaster Gloss (KB-3164 OPV) allows the printer to pattern-apply oil-based overprint to protect digital print. In addition, the inline combination of Lithomaster Strike-Thru overprint varnish with a Kentucky Shine gloss overprint on any multicolor litho press enables further enhancement of the printed piece. This Strike-Thru process can be used to achieve a matte and gloss combination in one pass. Reticulation finishes also are available.

Making Offset Print “Pop”

So-called hybrid printing presses – often an offset press with a flexo unit for varnishing – are nothing new. Sheetfed printers have been adopting flexo chamber coaters for instant-cure ultraviolet (UV) printing for several years, starting out doing flood coats (full pages) then migrating to the ability to achieve intricate spot-varnish applications.

“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.

Future waves

So what might be next on the horizon in terms of emerging coating technologies? If UV-LED was a sign of things to come back in 2008, what harbinger will Drupa 2012 bring? Metcalf thinks it may be high-wavelength UV that is even more faster-acting and more energy-efficient than LED. “With high-wavelength UV, the UVA spectral range is skewed,” he explained (see factoid below). “It has a photo-initiation reaction that is higher on the [UV] color spectrum,” causing it to act faster.

AMS’s abbreviated name for this is HWU V. Komori, which launched its version of the curing system at the Ipex 2010 in the U.K. calls it H-UV. The technology uses a UV lamp and high-sensitivity UV ink. With just one lamp mounted in the delivery of a Lithrone sheetfed press, for example, H-UV offers high print quality and reliability as well as excellent economic and eco-friendly performance. The most cool thing about it, said Metcalf, is that “it’s compatible with existing UV light sources and uses the same class of inks as LED ink.”

The bottom-line impact is that fewer lamps are deployed for high-speed curing, making UV coating technology even more accessible to the print masses. H-UV, HWUV: Whichever acronym you choose, it’s sure to shake things up down the road.

Additional Information

5th Annual Print UV Conference

March 11-13

Encore, Las Vegas

The Print UV Conference bills itself as the premier all-in-one conference event for leaders in the global UV printing industry. Some 200 attendees meet annually in Las Vegas to network, engage with printers and leading suppliers, uncover new ideas and growth opportunities, dive deep into core UV processes with experts from multiple fields, and hear case studies from successful UV print initiatives around the world. If you're a commercial, packaging or specialty printer and are serious about UV, you won’t want to miss this event. http://www.myprintresource.com/10615145/

UV Factoid:

(Source: Wikipedia)

Ultraviolet (UV) light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nanometers (nm) to 400 nm, and energies from 3 eV to 124 eV. It is named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet. The UVA range is wavelengths from 315 to 400 nanometers. Wavelengths from about 345 to 400 nm are used for “Blacklight” effects (causing many fluorescent objects to glow) and are usually very slightly visible if isolated from more visible wavelengths. Shorter UVA wavelengths, from 315 to 345 nm, are used for suntanning.