Flexo Printing
By Steve Katz, Editor | March 13, 2014 (Article sourced from labelandnarrowweb.com)
Components of the label industry’s primary print process continue to advance, driving flexo’s evolution.
Printing industry historians date the origins of flexography – once called aniline printing – back to 1890, and for half a century the process was widely used in food packaging. But, in the 1940s, when the Food and Drug Administration classified aniline dye inks as being toxic and unsuitable for food, printing sales suffered. A turning point came when the process got its new name, flexography, in 1951, which occurred around the time new and safe inks were developed for its use, and flexo got the go-ahead from the FDA.

Flexo’s acceptance coincides with the emergence of the pressure sensitive industry, and today it remains the industry’s dominant process. Flexography has history, and recent developments have the process standing toe-to-toe with print methods long considered to have better quality. “Flexo printing really started to evolve in the 1950s for all types of applications – corrugated boxes, other types of packaging, along with labels and tags,” explains Deanna Whelan, global marketing manager for Flint Group Narrow Web. “Today, flexo printing has developed to be a viable alternative to offset and gravure techniques, which have long been established as high quality methods.”

Flexo is the fastest-growing analog printing process for use in label printing, and is continuing to make inroads. According to Smithers Pira, a market research firm specializing in packaging, paper and print industry supply chains, global demand for flexo printed pressure sensitive labels will rise from 13.3 billion square meters in 2012 to 15.8 billion in 2017. Within these totals, North America and Europe lead the way, with Asia predicted to catch up significantly during this five-year period.

Flexo’s growth and success can be attributed to a number of factors, because there are so many elements within the process working in tandem, complementing each other throughout the workflow.

Lee Zerfass, digital business manager for Anderson & Vreeland, emphasizes that today’s flexo is about more than press technology. He says, “Flexo printing continues to evolve, capitalizing on the mechanical advances in the presses themselves – makeready requires less time, there is less material waste and coming up to color is much quicker and more predictable. But we’re also seeing advances in plate materials, mounting tapes, sleeves, anilox rolls, doctor blades, curing, etc. The quality is improving on every touch point to the press itself.”

At the end of the day, advances made by flexo are resulting in labels that appeal to consumers and end users, which is what keeps printers in business. “Flexography is no longer the simplistic process that it used to be,” says Emma Schlotthauer, global packaging marketing manager, Kodak. “Major advancements include the adoption of digital flexo plate technology, the widespread growth of UV ink systems, combination presses, press automation, and advancements in servo press technology. All have been necessary to meet the demands of end users for more complex graphics, vibrant colors and eye-catching special effects, and the needs of the printers for shorter set up times, faster press speeds and an overall drive towards a more efficient, cost effect manufacturing process.”

Fast, flexible flexo
There is no argument that the inroads made by digital printing technology over the last decade are impressive. However, flexo remains the label industry’s primary printing process, due to its speed, versatility and quality.
“Forecasts continue to report 3.8% growth in flexo printing for labels and packaging through 2016,” says Mary Sullivan, director of global marketing for flexo press manufacturer Mark Andy. Sullivan says that despite facing some adversity, such as the economic recession, government trends towards sustainability, shorter runs, the technology and process is strong. “One clear trend that continues is in consumer products, and this means packagers and packaging producers are pressured to get products to market even faster. The result is the need for faster and faster turnaround in all phases of product introduction, speeding up the design approval process and, more importantly, the pressure on print-readiness and skilled, efficient prepress and on-press operations to avoid delays and errors,” she says.

The flexographic process is aptly named. In addition to speed, its flexibility is one of its hallmarks. “Flexo means versatility,” states Steve Leibin, executive VP business development for Matik, Italian press manufacturer Omet’s North American distributor. “Flexo represents an inline production method that produces unique, innovative products in a cost effective, single step process. In the past, label printers printed more simplistic pressure sensitive products. Today’s label converters print on multiple substrates, building multi-layered and other intricate products on narrow and mid-web presses.

“Packaging is growing and the inline flexo process is growing with it,” Leibin adds. “As brand owners continue to look for ways to differentiate their product on the store shelf, label printers will continue to deliver unique and innovative products produced on inline combination printing presses that are based on flexo technology,” he says, adding that areas of growth for flexo printers can be found in printed electronics, laminated films for pouches produced inline, and multi-layer coupon labels.

Eric Hoendervangers, commercial director for Dutch press manufacturer MPS, touts flexo’s flexibility as well as its efficiency as a one-pass inline process. He says, “Flexo print technology still dominates the label printing industry, and it’s for a couple of reasons. First, flexo provides great benefits in flexibility and color opacity. Second, inline-converting is often technically needed or, economically the only answer, and cannot be separated in an offline process.”

For Hoendervangers, flexo’s benefits can be broken down into five core points. He says, “Flexo printing and press technology meets the five label production parameters the best: flexo prints high quality CMYK; it has excellent and stable color densities; flexo can be easily combined in line with other desired converting technologies; it offers the highest productivity and flexibility; and flexo presses are easy to operate and control. These five parameters are perfect for label manufacturing and guarantee both customer satisfaction and converter profits.”

With digital printing proponents trumpeting its sweet spot, short run work, and also no need for plates, Hoendervangers notes that flexo press makers are engineering machinery designed to compete. He adds, “There are some very interesting innovations in new press technologies that are decreasing the running costs per 1,000 labels, thus enabling flexo to compete with digital. And last but not least, increased investments are being made in prepress technology to decrease the cost price of a printing plate.”

For Mark Andy’s Mary Sullivan, flexo developments are not necessarily responding to digital, but responding to the converter and what drivers are affecting productivity and profitability. She says, “A successful ‘print shop of the future’ will offer hybrid technology – digital, flexo and other printing and converting processes in highly integrated platforms. These hybrid lines will put a new level of flexibility, configurability, and ultimately more control in the hands of the converter.”

Plate advancements
High-definition, or HD Flexo, from prepress equipment and software supplier Esko, has closed the quality gap between flexo and its rivals offset and gravure. HD Flexo is a new process for making digital flexo plates, resulting in improved plates that are higher quality and can print more consistently than standard digital flexo plates.

Platemaking has made strides in the processes of exposing plate material with flat top dots, either in the exposure processes or integrated into the plate material itself. “There are new screening technologies for high definition/high resolution allowing for 4000 to 5080 dpi that have doubled the resolution,” says Anderson & Vreeland’s Lee Zerfass. “This improves type, drop shadows, highlight and shadow details that now print cleaner. For line work, everything looks sharper, positively effecting nutritional panels and micro-printing. There are CtP devices using higher wattage lasers and advanced optics to ablate the carbon masked plates. In the same pass, an LED exposure head makes the face exposure process. LEDs used in exposing and curing are eco-friendly, and last for thousands of hours while expanding our choice of substrates.”

As a plate supplier, Zerfass sees continuous improvements in plate quality, image reproduction via dot shape/structure, ink transfer, and durability. “Plate manufacturers are satisfying the demand for higher resolution/line screen counts while reducing dot gain,” he says.
While press manufacturers continue to improve in mechanical print quality and efficiencies, plate manufacturers are refining plate attributes to specific applications. “They’re getting really good at identifying raw materials that provide better print quality for different substrates. Increased line screens, higher count anilox cylinders, mounting tape technologies, and curing techniques are all contributing to great consumer products,” Zerfass adds.

Jim Krstulic, national account manager for INX International Ink Co., emphasizes improvements in printing plates have contributed greatly to ink’s role in the flexo process. “The introduction of core new polymer materials, surface manipulation of the dots, and advancements in software and processing equipment all help to increase the acceptance and transfer of inks to the substrate,” he explains.

Inks and anilox rolls
Many variables play a part in the flexo printing process that effect the end result. In addition to presses and plates, inks and anilox rolls play a pivotal role in the final printed product.

“Inks providing far better dot reproduction, anilox rolls designed to control the amount of ink deployment, and recent developments in plate technology which allow ultra fine dots and micro embossed solids, high definition printing via flexo has become a reality,” says Deanna Whelan, of Flint Group Narrow Web. “And, those who drive the flexographic industry continue to improve all the moving parts – and, with this, the printed results become better and better.”

Known as the “heart of flexo,” anilox roll manufacturing has had some key breakthroughs. “In the past three to four years years, flexo printing has evolved more than any other print engine in today’s graphic arts industry,” notes INX’s Jim Krstulic. “New engraving technologies with anilox rolls have played a major role, not only achieving higher count lines, but more importantly, higher cell volumes and cell configurations that help carry and transfer more ink to the plate.”

Alex James, director of Harper GraphicSolutions, discusses some of these newer anilox technologies. He explains, “Anilox rolls have evolved by moving to higher engraved cells such as those with engraving rankings from 1200 cpi to 1800 cpi for the narrow web industry. Advancements include improved fiber optics laser technology, which has contributed to the higher engraving cell patterns. Harper Corp. offers XLT-60° Hex cells, 30° channel cells, longer cell patterns and a range of channel engraving cells. Here, the channel engraved cells are used for specialty application demands like glitter, metallics, thermochromic and tactile effects.”

Along with the evolution of higher line anilox rolls and new plate technologies, inks have also undergone major advancements. “Inks needed to evolve in several ways,” Krstulic says. “First, ink makers look to increase the pigment load as much as possible, grinding that pigment to its smallest possible particle size to capture the ultimate strength and gloss attainable. Next, the resin selection must be such that it provides the ink with exceptional resoluability, transfer and the wetting-out properties on the various porous and non-porous label substrates.

“Tomorrow’s inks will need to be stronger and have more solubility for cleaner printing, have better stability on press and will need to have better acceptance and release to the anilox roll, printing plate and substrates used,” Krstulic says. “The injection of specific additives such as defoamers, waxes, surfactants and others play an important role in how ink runs on press for any specific label application. New resins and supporting raw materials are constantly being introduced to ink companies for usage consideration.”

Flint Group’s Deanna Whelan stresses that the single most important development in flexography from an ink maker’s perspective is the development of UV flexo ink technology. Though the technology has been around for more then 25 years, it is constantly developing. “With the color density achievable today, UV flexo is far superior compared to the early ink developments,” she says. “With today’s ink formulations, you can achieve much higher color strength, making it possible to achieve process densities using ultra fine anilox roll cell structures which allows you to run very fine line screen counts, up to 225 lpi, creating the highest possible print quality.

“UV LED ink and lamp technology is truly a game-changer,” Whelan adds. “Inks have been specifically designed for use with UV LED lamps – conventional UV inks cannot cure using UV LED lamps – specific formulations are needed to address the narrow and targeted wavelength area typical for UV LED lamp output. UV LED will increase press uptime – instant on/instant off technology, lower maintenance lamps, and deeper curing inks play a part in this. UV LED is safer and environmentally friendly – there is no hazardous mercury and ozone. And, with this technology, printers will realize a significant reduction in energy – 50 to 80% reductions are possible.”

Another flexo ink advancement relates to food packaging – high quality low migration inks. “As the need for low migration inks for food packaging and labels have led to many breakthroughs in ink technology, the industry now has low migration UV flexo, UV offset, and UV flexo metallic inks. Inks are readily available all around the world to support these applications and the sometimes very strict regional regulations,” says Whelan.

With so many forces and moving parts at play, all of flexo’s components must not only work together but also advance together. Take for instance the development of UV LED – the partnership was between inks, lamps, and the printing press. “The right combination and development of all three were integral to the success of the final result,” Whelan says.

Overall, many factors have played, and continue to play, key roles in the evolution of flexography. Presses, inks, plates, prepress technology, anilox development, and the changing demands of brand owners and end users are driving flexo’s continuous evolutio