by Melissa Donovan
The corrugated packaging industry includes the manufacture and use of corrugated containers and associated packaging materials and products, based on a definition from TAPPI. Converters, printers, suppliers, and manufacturers participate in this space.
Demand for printed corrugated product is at an all-time high, especially as shipping of consumer goods continues at a steady pace. Vendors look to create corrugated boxes that are part of the buying experience. Often, this means including graphics and messaging that changes quickly.
“Brands search for alternatives to traditional packaging designs for purpose of differentiation,” notes Jonathan Fore, director, product management, Baldwin Technology.
Corrugated board was once—like all mediums—only printed to via analog processes. Improvements are still being made on the digital side of things because of how unpredictable the material can be, this is particularly in regards to vacuum table—board holddown—mechanics and avoiding printhead strikes.
Ink composition and curing systems make inkjet a viable alternative to analog. UV/UV LED ink sets are proving advantageous in this space for multiple reasons including durability, flexibility, and dependability.
To bring it full circle, UV/UV LED printing is ideal for today’s customized, shorter run corrugated projects.
When and Where
UV/UV LED inks are used when printing to corrugated in both single- and multi-pass printers.
With single-pass printing, Ken Hanulec, VP worldwide marketing, EFI, explains that users look for high-speed printing and UV ink with LED curing that offers reliability and productivity.
How is the possible? “UV LED inks do not need drying, which provides an extra benefit in terms of sustainability—the reduction in the amount of energy required to cure the ink printed. UV LED also offers other advantages such as virtually zero emissions to the atmosphere, repulpability, and the fact that it can be used in a range of applications. LED curing is superior to traditional arc curing in terms of productivity gains and operational cost advantages,” continues Hanulec.
“UV inks are the primary ink used in single-pass printers for corrugated paper in the North American market and much of the rest of the world, excluding Germany who has tried to push against UV suppliers. UV ink and related single-pass printers can offer a robust, saturated print that is quite difficult for water-based inks to duplicate,” states Lloyd Kent, VP sales and operations, North America, Kento Digital Printing.
Errol Moebius, president/CEO, IST Americas, believes UV/UV LED inks are favored in single-pass printers in the case of corrugated printing. “The main reason for this preference lies in their curing system. Unlike water-based inks, where multi-pass printing was necessary, UV inks can accomplish the same in one pass due to their instant curing nature. This instant curing attribute of UV inks allows for single-pass printing, especially for solid, single spot colors.”
Fore says that for single-pass digital presses, UV or UV LED is used for three reasons, when a high-end, finished look is required, print quantities are low, and if the substrate is plastic corrugated.
UV inks are also popular for multi-pass corrugated printing. According to Steve Lynn, director, labels and packaging, Durst Image Technology US, “UV inks are more often seen in multi-pass printers as they address the short-run, corrugated display market.”
“UV printing onto corrugated board is used in higher pass modes. One of the reasons is to print more on demand or shortened runs—shorter runs with higher image quality and full-color graphics,” agrees Jay Roberts, product manager – UV printers, Roland DGA Corporation.
Meeting Demand
UV printing for corrugated applications offers a host of features that allow users to achieve success. Manufacturers and converters require dependability, versatility, and reliability from these printers.
“Users look for dependable curing/drying of their print with a dependable system that has low to zero maintenance and with components that can be maintained by their operators,” shares Kent.
Moebius agrees that dependability is a necessary attribute. “The primary request revolves around achieving a consistent and repeatable process. As these systems utilize 100 percent solids, the daily production shouldn’t be affected by moisture or weather conditions. Both durability and consistency are crucial factors, and as time progresses, costs—comparing water-based, mercury, and LED curing systems—will inevitably gain more significance.”
Versatility is another consideration, more so for print service providers over manufacturers. “Print providers using a UV curing system to produce corrugated work are most concerned with versatility; print providers want to accomplish as many applications as possible, like printing on plastics and papers, with as little equipment as possible for profitability’s sake,” adds Lynn.
Hanulec lists reliability, reduced energy consumption, durability, resistance, and flexibility as main requests from users.
A compact device is also advantageous. “Being more compact means a user can fit a machine on their plant floor and requiring less power may be the factor that opens a path to place a single-pass printer in their facility that much longer machines cannot do,” explains Kent.
According to Ken Parsley, product applications engineer, Mutoh America, Inc., the real goal is fast print speeds at an acceptable quality level.
“Today’s packaging buyers want to achieve greater marketing value with their boxes, and as a result, we see packages that feature increasingly complex, detailed messages and more vibrant color. That trend, in combination with another important factor—the increase in UV flatbed print speeds—have really changed the packaging market,” says Roberts.
Technological Advancements
UV/UV LED inks—and by extension the UV curing systems in place—continue to advance.
Arc curing systems are being replaced by LED curing “due to economic benefits, primarily through productivity increases and operating cost advantages,” shares Hanulec.
“LED technology has been integrated into digital decorating from the start, creating a natural connection. Over time, LED systems have significantly improved, becoming more potent and offering a wider range of parameters that can be monitored, enhancing process control. As the cost effectiveness of power consumption between LED and traditional UV becomes more critical, LED options might gain more traction. However, the expenses related to consumables also need to align with this shift, gradually becoming a more influential factor over time,” foresees Moebius.
The transition to LED curing lamps is a huge benefit to corrugated. “In particular, since corrugated deformation is amplified by heat, the low heat generated by UV LED presents advantages in the corrugated space. For many users, cold curing allows them to print on a much wider range of substrates, both thick corrugated and thinner microflutes,” explains Hanulec.
“With a strong move to advance from UV to UV LED inks, systems for curing LED inks provide less heat on the corrugated surface, which helps the board remain flat and not be affected by heat,” continues Lynn.
Parsley adds that UV LED curing systems also operate much closer to the visible spectrum, which greatly reduces the risk of eye damage.
Besides the curing systems, the ink itself is changing—in a good way. “UV inks designed for corrugated are flexible enough for folding and strong enough for creasing. They are fully repulpable and recyclable and contribute to the circular economy of corrugated,” shares Hanulec.
“With so many ink manufacturers making UV inks and primers for single-pass machines, the competition is quite high and ink costs are being driven down. This has to continue for a greater adoption of single-pass machine purchases to happen in the ultra-competitive corrugated packaging industry, especially for companies that run a lot of boxes and not as much display work,” suggests Kent.
Water-Based Side
Despite advancements in UV technology, water-based inks are an important player in digital corrugated board printing.
“The dominance of water-based inks is due to their cost effectiveness, ease of application, and the availability of equipment for curing. Additionally, for lower resolution printing on corrugated surfaces, especially for heavier coverage areas, cost sensitivity is a significant factor influencing this choice,” notes Moebius.
Health and recyclability are two main reasons. “Recyclability is a large motivator to print with water-based inks. Water-based inks play a critical role in food packaging as it relates to migration, and that is a great opportunity for packaging print providers,” says Lynn.
Flexibility and longevity are other factors to consider. “Water-based inks have more flexibility than UV inks. A water-based pigment ink has a longer longevity than water-based dye inks. In addition, water-based inks can be FDA approved for direct and indirect food contact,” explains a representative from Konica Minolta Business Solutions U.S.A., Inc.
Hanulec doesn’t believe “water-based inks dominate digital corrugated printing, at least not within most state-of-the-art technology, which is industrial single-pass printing. The number of installed machines using UV technology is higher than the water-based lines—excluding China.”
While Hanulec admits that water-based inks are well known and valued in the packaging industry—primarily for their inexpensiveness and lack of photoinitiators—UV-curable inks still provide advantages in terms of speed, drying time, energy consumption, and abrasion resistance when it comes to high-productivity printing.
“Water is a very safe carrier, but it needs to be absorbed or evaporated to dry. This is not so much a challenge in slower consumer inkjet printers, but for high-speed printers, sophisticated and high-energy drying systems are required, often along with a primer/pre-coat on the substrate that controls the dot gain of the ink droplets as they are dried. It also limits what additives can be added to the ink to increase performance like binding to certain substrates, causing many water-based ink systems used for corrugated printing to use a post-coat to protect against abrasion and scuffing,” continues Hanulec.
Another disadvantage to water-based ink is the required plant floor space. “Plant floor space needed for water-based systems is tremendously higher because of the extended drying sections of the machines and energy costs are extremely higher because of these large drying sections needed to evaporate the water for the ink,” states Kent.
Moving Forward
Pushing users toward UV printing for corrugated is a challenge, but one that can be overcome.
First off, it’s important to combat any misinformation out there. “Most providers of water-based inks promote to the industry that you cannot use UV inks in food packaging. This is not true. All of the major ink suppliers, including those who provide flexographic inks to the corrugated industry will tell you their UV inks are well suited for food packaging. These ink suppliers continue to drive the cost down as has happened in other digital industries and this helps advance single-pass digital in the corrugated industry,” explains Kent.
“Educating end users about the practicalities of using UV or LED technology is essential. This includes providing insights into the operational reality of these systems. While UV inks might incur slightly higher costs—around ten percent, they are more efficient in usage. Additionally, they entail lower energy costs, among other benefits. Hence, there’s a need for an educational initiative to highlight these advantages,” admits Moebius.
Parsley notes that care needs to be taken in regards to the corrugated media itself. “In my experience, printing on corrugated is more about the media than the print system. Maintaining the media in a manner that allows it to remain flat and straight is the biggest challenge. UV LED machines are very capable of printing on this substrate if it is capable of lying flat. A strong vacuum on a flatbed device can correct for some warping but not all.”
Mar2024, DPS Magazine
