Cures for Wider Webs?

Flexo has long been crowned the fastest growing graphic arts application for UV technology, and experts say usage continues to climb across all press widths. On narrow-web presses in particular, UV curing systems have moved decisively into standard component territory. “Now it would be very rare for a [narrow-web] press not to have at least one UV [unit] … and most presses are all UV,” affirms John Mitchell, sales/product manager, UVTechnology.

By contrast, UV ink usage remains more of a specialty than a must for mid- and wide-web flexo printers, but interest has reportedly been building in the past several years, particularly for mid-web presses, and more generally in wider flexible packaging and folding carton applications. But will UV printing ever achieve its narrow-web pervasiveness at wider widths? What factors could help it gain momentum?

Mark Hahn, vice president of sales and marketing for AAA Press International, chalks up the slower rate of mid- and wide-web acceptance to “penetration of both solvent- and water-based ink systems in these markets.” Hahn observes an increasing UV usage in mid-web, where printers are interested in capitalizing on UV’s high-density, 100 percent solids ink systems for improved color vibrancy and opacity. He has seen some printers install one or two UV units on wider presses to lay down dense white UV inks, and then print water or solvent inks over the white for a more vibrant result, particularly in film applications. Other mid-web printers have made a complete conversion to UV for certain applications that require high-end, 200-lpi process work, he says.

UV top-coat and varnish units are still most common at wider widths, says Joe Ooten, vice president sales and marketing, IST America Corp. He sees overcapacity of solvent- and water-based ink technologies in the traditional flexible packaging segment (beverage labels, food packaging, etc.)—and thus, little incentive to convert. He believes UV conversion opportunities will arise for these printers when the time comes to add capacity. Alternatively, UV printing in wider folding carton applications, “is growing like gangbusters,” he says, citing a number of IST installations this year on 40˝ to 50˝ presses for this purpose. Drivers include capacity additions and interest in new designs, he explains, adding that UV inks “are structured to the box, and help protect the ingredients inside.”

Brian Wenger, vice president at GEW Inc., connects wider-web, flexible pack­aging converters’ “capital cost and conservatism” to UV’s slower spread in the sector. Another contributing factor, he says, is the “secretive” nature of CI UV flexo printers who are targeting the gravure market. “We would expect to see the adoption of UV flexo printing for this category to grow at a conservative 20-30 percent per year in North America,” he sums up.

Weighing wider issues

UV ink formulations bring a sizeable roster of plusses to print jobs of any width, including color consistency throughout the print run and from job-to-job; quick job startups, changeovers, and clean-ups for reduced waste and downtime; notable dot gain control; minimal feathering; high gloss, wear, and scuff-resistance; and the potential to reduce the need for a coating or laminate in a job. But how do these benefits uniquely manifest at wider widths?

In longer runs typical for mid- and wide-web presses, Hahn believes UV’s stability and consistency can be a key factor in maintaining an ink system, and ultimately producing higher print quality. He also contends mid- and wide-web printers can maximize downtime reduction by using UV inks in combination with sleeve technology, bringing quick cleanup (because UV ink does not dry on the printing plate) and job changeovers (with sleeve-based efficiencies).

Elinor Midlik, president of Prime UV Systems, emphasizes that UV inks and coatings add “cosmetic appeal … to wide-web applications such as preprinted linerboard, multi-wall bags, folding cartons, and point-of-purchase displays”—maximizing their ability to grab consumers’ attention on the shelf. She also says some wide-web converters have found UV flexo offers a less expensive alternative to heatset printing using water-based inks and coatings—in light of recent acceleration in the costs of natural gas for heatset ovens, and utilities for running afterburners or incinerators.

Like other ink types, UV inks can be used in food packaging if a functional barrier is present between the ink formulation and the food product, or if the printing is on the exterior of the package. FDA clearance for UV inks that directly contact food could pave the way for additional applications. RadTech International North America is working to facilitate clearance for UV/EB inks through two focus groups, the Food Contact Notification (FCN) Alliance and the UV and EB Food Packaging Alliance. According to meeting minutes posted on RadTech’s Web site, the FCN Alliance intends to submit data on commercially viable formulations to the FDA this year.

Wider-web printers must be mindful of unique UV concerns related to their equipment and commonly run materials. Hahn says thin films frequently used in flexible packaging applications, “will require ‘cool’ UV systems to control web temperatures, which can increase the overall system cost by as much as 30 percent.” To match ink chemistries at the speeds required for wider-web equipment, he recommends 600-watt-per-inch lamps and two to three lamps at the final station to ensure full cure.

Mitchell suggests paying particular attention to energy production of UV lamps in wider web applications. “As lamps age, their energy output can diminish and curing is therefore reduced,” he explains, advising regular use of a measuring device and careful recording of bulb changes.

Wenger underscores issues that may crop up for mid- to wide-web CI presses, where space limitations may require press manufacturers to alter the print-unit configuration to accept the UV unit(s). He also notes “thermal impact on the central impression (CI) cylinder can negatively impact on registration, curl, and tension,” adding that UV system manufacturers have developed “sophisticated heat management systems” that mitigate this effect.

Hot spots for growth

As suppliers and advocates continue working to achieve further UV flexo acceptance among the wider-web set, experts cite a number of factors that are already driving growth.

Hahn sees narrow-web printers taking UV technology wider, with 20˝ to 30˝ machines incorporating UV units, “to service a variety of markets from flexible packaging to labeling to folding cartons.” He also predicts wide-web printers will “aggressively pursue” UV technology in response to packaging buyers’ requests for UV flexo printed packaging.

Mitchell also sees application requests as a catalyst for UV’s expansion. “We have converters calling every week with new applications that their customers and designers have proposed,” he says. Mitchell sees more sophisticated graphics; new substrates with different properties; security printing; low odor inks for packaging and cosmetic applications; and the use of UV to apply adhesive during the converting process as hot growth that bode well for wider-web UV adoption.

Midlik maintains, “we see our strongest growth in curing of UV inks and UV coatings on flexible packaging for food products. All types of food packaging [such as stand-up pouches, PET bottle labels, folding cartons that will contain frozen foods, cookies, bacon, cereal or milk, etc., or baked-food cartons with see-through windows] are processed with UV curing equipment.”

As for UV curing system suppliers, “our challenge is to be more efficient with the energy we are using,” Ooten comments, noting efforts to develop systems that not only use less energy, but create minimal energy (heat). “If we can make UV curing more cost-effective and more viable, we can help grow the market.” n

UV’s place in the wide world

Industry insiders confirm UV’s expansion on both inline and CI wide-web flexo presses, though the progression on CI equipment has lagged behind a bit due to space constraints.

For flexible packaging applications on both inline and CI flexo designs, Prime UV Systems offers the FLEXfilm curing system, featuring an open-base UV lamp facing a water-cooled chill roll. Suitable for retrofits, the system requires less than 6˝ of space in the web direction. Controlled by the computer-based Smart 2100 Control Platform, the system offers on-screen and remote diagnostic capabilities.

At Labelexpo, GEW will introduce ISO-cure, a UV curing system with a water-cooled reflector profile designed for processing a variety of substrates on wider 18” to 57” presses. ISO-cure is designed for integration in compact spaces, such as on CI flexo presses. The system features the e-brick electronic power supply and a built-in heat exchange system to minimize exhaust air temperatures.