Image: Ink World

Energy curing technologies have been growing in popularity due to their efficacy, sustainability and usefulness in a wide range of applications. The process is often referred to as radiation curing, or “radcure,” because both ultraviolet (UV) and electron beam (EB) are radiant energy sources.

Unlike other methods of curing, exposure to light is comparably non-hazardous. Additionally, this technology is typically less expensive than conventional coatings. In the past, hesitation to utilize this technology has stemmed from yellowing or cracking. In today’s market, however, those concerns are rarely warranted.

Growth in this market has been steady over the last few years. In fact, according to Kelly Kolliopoulos, Flint Group’s global marketing director for narrow web, for the narrow web global market, UV flexographic printing is seen as the fastest growing conventional printing process, with an expected growth rate of 4% per year.

“UV flexographic inks and printing systems provide high quality and better consistency in print, with good printing speeds and press productivity,” Kolliopoulos said. “UV flexographic printing is the number one printing technology used by narrow web printers, and is used for printing pressure sensitive labels, tags and tickets and other applications that can withstand higher process temperatures.

“UV LED flexographic printing inks are in their fourth year of use in North America, and are starting to penetrate the other regions around the world,” Kolliopoulos added. “UV LED curable inks provide reliable cure at high printing speeds because of the penetration depth and intensity of the LED curing lamp. The cooler process temperature of this print technology enables the converter to expand their business into short run flexible packaging and shrink sleeves. For these and other reasons, the North American market for UV LED curing inks has quadrupled in the last three years. EB curable inks are slow to penetrate the narrow web market due to the asset intensity of this printing technology. With the availability of low migration or food compliant inks for use with either mercury or LED UV systems, there is less need for a narrow web printer to adopt EB technology.”

Jonathan Graunke, vice president of UV/EB technology for INX International Ink Co., believes that this market is seeing strong growth.

“Like years past, we are seeing solid growth across our UV/EB inks and coatings, with sheetfed UV, H-UV type, and LED being exceptionally strong. We are also seeing high growth in our UV/EB coatings offerings. The ability to sustain year-over-year growth is a testament to the benefits of UV/EB technologies,” he said.

For its part, Toyo Ink Co., Ltd. has seen sales of high reactivity UV inks for offset, which includes LED and HUV types, rise not only in Japan but also on a global scale.

“In particular, interest in low-energy curing systems was strong in the US and Europe,” said Tadashi Nakano, manager, Global Innovation Division at Toyo Ink Co., Ltd. “The market for UV inks and highly reactive UV inks continues to grow, driven by an expanding packaging market with a wider range of base substrates as well as a growing commercial printing market brought about by UV’s superior resistance and cost-saving benefits.”

Nakano added, “Growth in the packaging industry, especially for food and beverage and pharmaceutical markets throughout Asia, has led to the increased use of UV ink for label printing.”

Toyo Ink has been fielding more inquiries from customers about its EB products following the drupa launch of its new EB flexo technology. “Having solved the wet-on-wet trapping issue and watched equipment technology continuously improve, we see tremendous growth opportunities in the area. Another good growth indicator for the radcure market is that, at drupa, all the new printing presses introduced by the leading press manufacturers were designed to work with either EB, LED UV or highly reactive UV inks,” Nakano said.

Environmental and other advantages

The advantages or both UV and EB curing are numerous, and in today’s climate, the value of reliable, cost-effective, eco-friendly technologies cannot be overstated. Robert Doerffel, head of corporate communications in Europe for hubergroup Deutschland GmbH, said that one common argument in favor of UV curing ink systems is the zero VOC content.

“Frankly speaking, this position can be discussed pretty emotionally, depending on the individual perspective,” Doerffel noted. “It is very hard to come to a final conclusion about which ink might be of the most environmental friendly type. In fact, the curing technologies with lower demand for electrical power are making energy curing inks really interesting, lately. Not only are the print production costs shrinking, but also its carbon-based emissions. In combination with the zero VOC content of ink components, three benefits can be marketed as environmental advantages.

“To our customers,” he continued, “environmental aspects seem to be one part of the consideration if it comes to a decision about a press investment and a potential change of the printing ink type. While short converting times seem to refer to the economical aspects, environmental aspects may be part of a marketing strategy. As mentioned above, the perception of this marketing aspect may differ from country to country and also for each individual.”

Graunke, of INX, said that the advantages of LED UV are well documented these days.

“The potential for power savings is the obvious one, yet not necessarily from the actual running of the LED UV lights. It’s the instant on/off where the energy savings really show, as you do not need to keep the UV light in standby mode. Also, the need for air flow is essentially gone, and there is currently no ozone produced. The lack of additional exhausting means installation on retrofits is fast. Another advantage of LED UV is the minimizing of IR heat, there is much less distortion with temperature sensitive substrates. On offset presses, many setups are currently using only one LED UV light, further cutting energy use. It is hard to really determine the overall market share UV LED has, since it crosses several printing platforms. In sheetfed printing, the use of UV LED has exploded as it’s a great entry into the UV market, and is so simple to retrofit. It has become a major part of our double-digit UV offset sales growth.”

He continued, “More than the air permitting advantages, the environmental impact of generating less waste by having product that is stable, and instantly ready for post processing is what may be driving customers. Also, newer technologies like LED for commercial printing is allowing some customers to generate tax credits for moving to best available control technologies. This helps cover the initial cost of investment. It is certainly something printers should investigate in their locale. Another big advantage is the lack of mercury from the light source, and power savings seen with LED by removing the need for exhausting, as well as instant on/off.”

Even though solvent-based inks still have the majority share in flexible packaging in EMEA, UV has, for a longer period of time, been the majority share of the business in narrow web, according to Nathalie Wirner, manager of corporate communications for Siegwerk Druckfarben AG & Co. KGaA.

“UV is also growing in sheetfed. As a result, there is no change in customer behavior regarding environmental advantages. There are advantages using UV over other technologies, such as higher gloss, no VOC, immediate processing in sheetfed, press stability and immediately post print processes possible. EB shows growth in some parts of the industry, mainly in food applications where low migration systems are mandatory,” she said.

Peter Saunders, global business director, digital, Sun Chemical, said that there is certainly a lot to gain from the developments in UV LED.

“LED lamps are especially useful for heat sensitive materials like plastic or film. Unlike mercury lamps, which require chilled rollers to reduce effects of heat on substrate, LED doesn’t require those because its infrared–free output has the ability to deliver energy to cure and keep things cool at the same time. Additionally, UV LED has a longer lifespan than mercury lamps and there is dramatically less drop off in performance over time. In terms of market share, we know LED is growing. In faster wide format inkjet presses, mercury lamps still dominate, but we would expect LED to become a major part of digital label and packaging presses as technology develops,” he said.

Sun Chemical manufactures UV and EB ink and coating formulations specifically for food packaging where low migration is essential. Most notably, the types of acceptable photoinitiators for food packaging and low migration applications continues to shrink.

“One major change is that Nestle has stated that BPA-based chemicals can no longer be used. Many brand owners are following this direction too. Some energy curable chemistries as well as low migration products did contain small levels of BPA.

Reformulations in some cases are needed in order to remove all BPA, including NIAS types (not intentionally added substance),” said Tony Renzi, VP, product management, Packaging Inks, North American Inks, Sun Chemical.

“Low migration EB inks and coatings are also developed which provide for optimum curing with irradiation by an electron beam,” Renzi said. “Curing usually takes place in an inerted chamber with a nitrogen atmosphere preferred when producing food packaging. The use of EB curables for lamination purposes continues to gain attention.”

Unlike UV, EB does not require a photoinitiator so there is no risk of photoinitiator migration in food packaging. “Thus, these inks inherently conform to regulations governing low migration packaging materials and positive/negative lists,” said Toyo Ink’s Nakano. “In addition, EB inks are low-temperature curing systems and thus suitable for the curing of thin, heat-sensitive flexible packaging films like PE, APET shrink films, PET and OPP. EB is a penetrative curing system for carton boards and paper. This ensures low odor and an ink that is virtually fully dried as it comes off the press.

“UV ink, on the other hand, has made great strides in recent years in developing inks for the food packaging industry. New low-migration inks and non-toxic ingredients reduce the risk of non-cured free radicals migrating to the packaged content. In addition, the quantity of photoinitiator in UV ink, namely UV flexo, continues to decline, further ensuring a safe product reaching the consumer.”

Like many other markets, raw material availability and cost are of concern for the UV/EB market. This market, in particular, is focused on acrylic acid, which, according to Jeffrey Shaw, chief supply chain, quality and business improvement officer at Sun Chemical, has been relatively stable.

“In 2016, we have experienced a relatively positive environment for energy cure raw materials,” Shaw said. “Feedstocks, such as acrylic acid and epoxies, have been generally stable to down a bit. However, recently we have seen some increases in isocyanates impacting the cost of urethane acrylates. There has also been volatility around propylene, which is a key feedstock for many energy curing products. Global supply capacity for monomers and oligomers has been in balance with demand, although there also has been some consolidation in the industry potentially impacting global supply dynamics. The only area of sustained cost pressure has been photoinitiators out of China into regions whose currency has weakened versus the U.S. dollar.”