Flexo inks enable the vast majority of label printing today, with some 90% of labels printed on flexo presses. With ink being a major label component, the industry’s leading suppliers employ well-educated and experienced individuals to perfect ink chemistries.
Not only must flexo inks offer excellent runnability and end-use performance, they need to adhere to the wide range of substrates currently on the market.
UV inks tend to be operator-friendly and lower in viscosity. Plus, they are available at a lower price point than in years past.
“UV and LED curable inks require no maintenance and thereby eliminate a big variable in the pressroom for label printers,” explains Bill Phillips, business development manager at hubergroup USA. “These inks will run consistently hour after hour, day after day, and can even be left in the press overnight. Water-based inks are very easy to work with and clean-up is fast for job changeovers. Color strength is very high, and it is easy to adjust up or down, if needed, by the printer.”
Ideally, converters are seeking longer and cleaner runs, as well as a host of other advantages. “Energy curable (EC) inks offer many advantages compared to aqueous systems,” states Jim Krstulic, product manager, Tag & Label, for INX International Ink Co. “EC inks provide a sharper dot, higher gloss and better adhesion across various substrates, as well as better scratch and scuff resistance, less maintenance on press, faster make-readies and overall better print consistency.”
“There is very low maintenance of the inks on press, as the plates stay clean because the inks never cure until exposure to the UV/LED lamp,” explains Tom Hammer, head of technical marketing at Siegwerk. “This results in high-quality printing over long runs.”
According to Hammer, flexo inks can run on most flexo presses at high speeds and provide easier compliance to food safety regulations. They feature low VOCs and leave no exhaust vapors, making for easy cleanup with non-hazardous cleaners.
The technology has not remained static, either. “We have seen improvements in various areas of the industry,” says Hammer. “From an ink perspective, today’s systems offer higher color strength, better adhesion and faster printing speeds regardless of the ink type and chemistry. Also, new technologies, like LED curing, have enhanced the ability of inks to cure faster and better, thereby providing improved performance at lower production costs.”
In today’s landscape, flexo inks must also meet a multitude of regulations, specifically when it comes to food safety. According to Tony Renzi, vice president, product management, Packaging Inks, Sun Chemical, regulations are continually tightened to help meet safe packaging standards, especially as brands and government agencies learn more about sensitive chemicals.
“The migration of chemicals on packaging continues to be an ongoing regulatory issue that we address at Sun Chemical,” Renzi says. “Migration requirements for safe packaging are set by global government agencies and depend on the end use of the package. Secondary versus primary packaging, and the type of food or drug that is placed in that container, help delegate the type of chemicals that can be used, along with the type of testing that needs to be implemented to ensure that the package is consumer-safe.”
Renzi adds that protocols usually call for extended temperature testing using food simulant chemicals, where the testing simulates a product sitting on a shelf for 6-9 months.
Here’s a look at what today’s leading ink manufacturers are offering:
ACTEGA North America offers a broad range of ink and coating systems that cater to prime label printers in food and beverage, health and beauty, pharmaceutical, nutraceutical, durable goods, industrial and scale labels.
“We are unique in our offerings of inks and coatings, particularly a wide and broad range of special effects,” says James Harris, North America business manager - Labels. “ACTEGA offers systems for shrink sleeves, IML labels and HTL labels, as well. Our ink and coating systems offer various resistance properties, receptivity to variable marking, stamping and decorating. We also offer coatings and primers for the various digital technologies.”
The company’s flexo inks work well with a wide range of film, plastic and paper substrates. In addition, the inks are optimized for higher resolution graphics, providing resolubility for eye-popping 4-color process work.
“Our ink systems offer enhanced press performance, yielding excellent runnability, handling and stability,” explains Mark Lambert, product manager - Labels & Flexible Packaging. “Our products provide many opportunities for new applications and constructions for our customers.”
The development of Cyngient was based on a perceived technology void in the narrow web industry. The company has designed a number of award-winning UV flexo products, including high elongation metallic and pigmented inks, which are used in the thermoforming market and do not crack.
According to Andrew Wasserman, managing partner at Cyngient, the company’s high-resolution UV flexo shrink sleeve inks have been optimized for the latest fine-line anilox technology. HYPERcure, its structural UV wet lamination adhesive for film-to-film destruct bond and cold foil thin layer adhesive line, was developed for improved transfer and the elimination of cracking with shrink sleeves.
Cyngient’s newest series of UV flexographic laminating inks prioritizes ink adhesion as a key component, especially when printing on unsupported films.
Wasserman says, “Cyngient believes that listening to our clients and planning accordingly are key to the success of a project. Our partnership with Sun Chemical has helped us raise our profile, with the exchange of technology serving as a true benefit to the label industry.”
Flint Group Narrow Web
In 2018, Flint Group Narrow Web launched a dual cure, mercury bulb UV and LED UV ink for shrink sleeve labels. The ink offers the robust adhesion and flexibility required to withstand the downstream processes involved in the shrink label converting and application processes.
According to Flint Group, the company will soon be introducing its second-generation dual cure UV ink for labels and tags. “We’ve updated the technology on our first generation Ekocure F to improve on-press performance while maintaining the efficiency benefits of LED curing,” explains John Pogatschnik, product manager at Flint Group.
Flint Group has formulated and tested its inks to achieve consistent performance for each application, including pressure sensitive labels, flexible packaging and shrink sleeving. “One size does not fit all applications,” says Pogatschnik. “Certainly, some overlap occurs, but as the application gets pushed to its limits, failures can occur. For example, if you are printing shrink sleeves for an application with a modest shrink, a standard UV ink may perform. However, a customer who wants a shrink sleeve on a highly-contoured container, like a trigger bottle, will require an ink that can maintain its adhesion and sharp graphics in the high shrink areas.
“We test and build the product to perform on both the most popular substrates and most challenging substrates for each application,” he adds. “The end result is an ink family that works for the masses and also the niche opportunities.”
Fujifilm has placed a strong emphasis on R&D for its ink technology. The company has recently added the following to the 300 Series LED/UV ink range: Metallics, fluorescents, extended life pigment options, adhesives, expanded gamut process set and several specialty coatings. In addition, Fujifilm has expanded the range to include a complete set of LED/UV inks for rotary screen. All of these can be cured with LED or conventional UV arc.
"We are continuing focus of new flexo ink R&D on LED/UV hybrid inks," explains Jon Fultz, business development manager at Fujifilm. "We believe the latest innovations in the inks and the Illumina LED ColdCure system we are selling as retrofit or via OEM's has brought us past the tipping point where LED will become the preferred choice for most of the tag and label flexo market."
Fujifilm's Illumina has been optimized to work in tandem with the company's ink technology. According to Fultz, customer feedback has been even better than anticipated. "The primary benefit with Illumina is we have removed the significant risk factor for converters of not knowing if the LED curing system will perform with the LED inks they would convert to," he notes. "We have done this by co-developing the Illumina LED curing system with our ink chemists. This allows Fujifilm to be the only package solution provider of ink and LED equipment that eliminates the back and forth between equipment and ink suppliers when performance issues arise. It makes the installation and conversion fast, simple and seamless. Converters know Fujifilm will support the entire package."
The company's 300 series ink series has been on the market for three years, and the product portfolio has seen multiple expansions during that time. Compared to LED inks of the past, cure speeds and breadth of adhesion range have been significantly improved, especially when used with the Illumina system, the company says. The price premium that once applied to LED inks has also been eliminated, as the 300 Series is a hybrid ink running as UV or LED, so there is no premium when running it as LED.
"From a clear and varnish perspective, much progress has been made on cure speed and reducing the 'yellowing' that was prevalent with conventional LED systems and inks," explains Fultz. "With Illumina and 300 Series, the yellowing issue has not been completely eliminated but significant progress has been made to the point that most converts find it acceptable for their customers."
Fultz anticipates that adoption for this technology will improve, especially as customers learn about the benefits. "While LED for flexo has been around for more than 10 years, there has been a very low adoption rate," he says. "This is due to the fact the systems were not made for flexo but simply applied existing LED technology to all types of printing. The ColdCure technology of Illumina is a completely differentiated disruptive technology specifically for flexographic printing that is enabling a mass transition to LED in the same way water-base transitioned to UV more than 30 years ago."
As part of its “Hydro-Label” line, hubergroup is now offering the Hydro Chromis series water-based ink system, which performs on multiple substrates. The Hydro Chromis series is available in standard and low odor formulations to enhance flexo label printing. Additionally, hubergroup has released its “New V” line of UV flexo inks from Europe.
“Our inks offer consistent, reliable performance, ease of use and availability from multiple Huber locations,” says Phillips. “They are all backed with excellent technical service, too.”
According to Phillips, hubergroup continues to expand its expertise in North America with multiple locations, providing products and services to label printers throughout the region.
The company has designed its products to be as versatile as possible. “Our water-based UV and LED flexo inks are successfully printed on polypropylene, polyethylene, polyester and foil substrates every day,” says Phillips. “Our water-based inks have become even easier to work with on press. They are very predictable and are suitable for every anilox BCM range. Our UV and LED curable inks have become thinner and stronger, and they will cure at faster press speeds than ever before.”
According to INX’s Krstulic, the company has launched several new water-based products for the label market. INXShrink is a water-based system designed for shrink sleeve labels, while AquaTech ION X is a water-based system for paper and film. Mylex IV is a water-based system for solvent/solventless lamination.
“AquaTech ION X is a unique, water-based flexographic formulation designed for paper but has adhesion on most top-coated vinyls and films,” says Krstulic. “ION X is a highly-pigmented system, running on anilox rolls of up to 1500 lpi, with exceptional resolubility and stability on press at a wide range of speeds.”
Meanwhile, INXFlex UV LM Shrink is an energy-curable ink system that has been developed for shrink, and INXFlex UV LED is an LED energy curable system. “INXFlex UV LED is a premium energy curable ink formulated for light emitting diode Lamps at a 380-400nm wavelength,” adds Krstulic. “It offers superior gloss and transparency at run speeds of up to 600 fpm. UV LED has excellent product resistance, is formulated benzophenone-free, and has a low pourable viscosity while having excellent holdout on paper stocks. UV LED is also suitable to the shrink sleeve and IML processes.”
Pulse Roll Label Products
Pulse Roll Label Products, following the success of its flagship UV flexo ink system, PureTone, has developed its water-based flexo ink system, PureAqua, using a similar concept and technology to deliver optimal print performance and color consistency.
“Although the majority of our business is UV flexo, many of our customers also use water-based flexo technology for printing on multiple substrates,” says Mikaela Harding, product manager at Pulse Roll Label Products. “We understand the need for color consistency on a global scale and the value of digital color management, as proven with our PureTone UV flexo ink system. We wanted to be able to offer a single water-based flexo ink system that could achieve the highest level of color consistency and print quality – and on different substrates. Our high-strength PureAqua ink system builds on the concept of offering a total color management solution and is formulated for use on coated and uncoated papers, thermal papers and films.”
Sato UK, a provider of bar code printing, labeling and RFID solutions, uses PureTone inks for its UV flexo operation, and the company has added the PureAqua ink system for its water-based flexo printing business.
Martin Clackett, print production manager at Sato UK, says, “We made the move to PureAqua to support our drive to achieve the highest quality of water-based flexo printing on both standard and thermal papers. The PureAqua ink system means that we need to use only one ink system for both substrates, making it more efficient and cost-effective while at the same time providing optimal print performance and accurate color to satisfy our water-based flexo requirements.”
Siegwerk continues to broaden and enhance its full portfolio of products to perform better and provide safer alternatives to its customers.
Siegwerk Narrow Web has recently launched UV flexo inks in the Orbis family. Sicura Flex Orbis and Sicura Orbis LEDtec offer high strength, monochromatic inks that are lower in viscosity, which offers benefits to increase color gamut, improve print quality, decrease waste due to spitting and increase press productivity, as these inks cure at very high speeds.
Siegwerk has also introduced the LEDtec family of products. “This UV flexo ink base and fluorescent colors, along with a system of rotary screen colors, are formulated to be dual cure – use with both UV mercury lamps and LED lamps – and are formulated with raw materials that are not classified as reprotoxic,” says Hammer. “Siegwerk is also offering a range of UV/LED inks for food applications that will comply with legislation for low migration in both flexo and offset technology.”
Siegwerk, which has long provided water-based flexo inks, has introduced a new ink system called Poly Screen III, which is designed for paper and film applications requiring very low press maintenance. Hyper Lam, also launched this year, is a water-based flexo ink for laminated structures, typically with solventless, UV and two part water-based adhesives.
Sun Chemical has developed a multitude of products for flexo label printers, including SunCure Accuflex UV, SunCure UV Flexo LED, SunCure UV Flexo Shrink, SunVisto AquaGreen, and SunUno Solimax.
SunCure Accuflex UV is a new UV ink system designed for primary and secondary food packaging that is not manufactured with Bisphenol A (BPA)-based materials and meets low migration specifications. Meanwhile, SunVisto AquaGreen is an ink system formulated with significantly higher levels of bio-renewable sourced resin content compared to other previous market offerings from Sun Chemical.
“Sun Chemical continues to provide the widest breadth of products available on the market for wide and narrow web flexographic printing,” states Renzi. “With products ranging across water-based, solvent-based and UV-cured flexo inks that cover a comprehensive application base, such as labels, flexible packaging, paper packaging, shrink sleeves and folding cartons, we offer performance attributes like heat-resistance, water-resistance, high adhesion or flexibility, and much more. Our ink products are complemented by our portfolio of coatings, varnishes and adhesives, as well.”
This past year, Sun Chemical launched a whole product portfolio of electron beam (EB), ultraviolet (UV) curable and LED curable inks that are all compliant for food packaging when cured properly, regardless of the print process, including SunBeam Advance EB, SunCure Advance UV, SunCure UV LED, and SunCure Accuflex UV.
Sun Chemical’s inks have been designed to meet the latest industry trends, as well as functioning with the most popular end-use applications. “Sun Chemical has seen many new challenges for inks to perform in different conditions,” adds Renzi. “Inks are being asked to do something new for converters all the time, and Sun Chemical has answered.”
Zeller+Gmelin has long been known for manufacturing UV curable inks and coatings, but the company has evolved with the industry trends. It recently added three water-based flexo inks, as well as LED curable flexo and low migration UV flexo products.
“Our water-based inks are exceptionally strong and very pH stable, making them especially appreciated by the press operators who run them,” explains Ed Dedman, flexo technical support/product manager at Zeller+Gmelin.
“Our inks will typically adhere to many difficult-to-print substrates, and they are generally ‘pour and run,’ without the need for the press operator to become an amateur chemist,” he says. “You name it, our customers are printing on it. We can generally lay on and adhere to many different substrates, and if we run into something especially difficult, we can usually develop an ink in the lab to make it work.”