By Cassandra Balentine
Ink is a demanding and complex area of the digital print process. Working in unison with the mechanics of the printer, software, and media, the right ink plays a significant role in an application’s substrate versatility, color vibrancy and accuracy, durability and adhesion, cost, and turnaround time.
Above: Agfa is focused on developing application-based ink sets for specific segments of key growth markets like industrial printing, packaging, flooring, and deco laminate printing.
As wide format applications continue to expand, so do the demands on ink.“To meet these vast indoor and outdoor applications, the criteria for today’s wide format inks continue to evolve,” says Deborah Hutcheson, director of marketing, Agfa Corporation. “Today’s inks need a high degree of flexibility, coupled with a wide color gamut, good adhesion on a variety of substrates for indoor and outdoor use, and low odor.”
Before embarking on a new equipment investment, print service providers (PSPs) weigh the benefits of different ink sets, which have a significant impact on the type of applications they can offer. In any scenario the goal is to find the best ink at a price that enables a profit.
Ink is a complex topic for PSPs. Ideally, one ink set would cover the range of applications within a shop. However, that’s a tall order. In some cases, multiple ink sets can be developed for a line of printing equipment so the PSP can choose whichever one best meets their needs.
Having an ink set that meets all client requirements is a challenge PSPs continuously face. “Not just from a color gamut standpoint, but actual ink options that would allow customer needs to be met like white printing, special effects, and additional colors to meet application demands. Above color and ink options, performance is also important, as well as adhesion and quality,” states Becky McConnell, segment marketing manager – wide format inkjet, Fujifilm NA, Graphic Systems Division.
Tom Wittenberg, large format industry relations and events, North America, HP Inc., says PSPs face many issues with ink, including hazardous storage, safety, health, spills, environmental reporting, disposal, ink line clogging, use on many substrates, and curing temperature requirements. Ink companies constantly develop new ink formulas to address concerns.
“Ink manufacturers are constantly exploring different ink formulas to make a better ink at a lower cost to the printer manufacturer, which ultimately trickles down to savings for their customers. Some printer manufacturers have even brought in their own ink manufacturer to eliminate some of the cost that gets passed onto the customer,” explains Chris Padilla, product manager, Mutoh America, Inc.
Improved turnaround time is a consistent requirement. “The age of click and deliver has ushered in a higher demand for fast turnaround. As a result, PSPs want fast or instant dry technology to keep up with consumer demands. In addition, PSPs want to manage cost and consistency. Inks need to perform on demand and deliver consistent results as quickly as possible,” shares Michael Maxwell, senior manager, Mimaki USA, Inc..
PSPs may prefer not to have multiple ink types on hand, as this presents the risk of using the wrong ink and increases inventories. “Unfortunately, current technologies require a harder ink for rigid substrates and softer inks for flexible media and in most cases separate printers. A big issue that many PSPs face is the lack of daily/weekly/monthly maintenance, especially with the ink delivery system and printer carriage assembly. It’s proven that PSPs who ensure proper maintenance enjoy better performance and longevity of the printer,” says comments Stephen Emery, SVP, IIMAK Digital Inks.
Inventory management is another challenge, especially for small shops that must be careful to rotate stock and limit purchases to what they will use in one or two months. “Typically expiration dates are one year but may be shorter by the time the customer receives them. There is a significant chance some inks will get disposed of before they get used. Running expired inks can damage machine components and add maintenance costs,” adds Ken Parsley, product manager UV/MP, Mutoh.
UV as well as solvent and eco-solvent inks—including latex, are widely used today, but popularity varies by geography and industry.
Phil Jackman, global product manager, digital, Sun Chemical, says the application primarily dictates the type of ink used. “When comparing UV- and solvent-based printers, those using UV inks are typically utilized in more demanding applications than solvent, which could be faster and wider machines as well as more challenging and varied end applications. Geographical differences do exist however, perhaps with the more developed countries and markets more focused on the wider application space delivered by UV inks and printers.”
While eco-solvent and latex engines may have the largest install base especially in small format devices, Hutcheson is starting to see a decline. “UV LED inks have consistently shown the largest annual growth rates and will continue to do so. This growth is fueled by the massive expansion of UV applications and the introduction of LED lamps. This widens the options even further, adding to the ability to print on more heat sensitive and thinner substrates.”
Sohil Singh, VP, Stratojet USA, feels that while latex, solvent, and eco-solvent inks are important, the demand for fast print delivery and multiple new print applications challenge many PSPs. Often, these prints require lamination before they are handed over to installers, or need to be mounted on a board before shipping out. “With output needed the same day, many PSPs now face order cancellations or having to ask end customers for more time,” he shares. UV offers fast cure times.
Another challenge is the application restrictions on latex and water-based printers, an area where UV tends to fare better. “Water-based ink technology is a sustainable solution but at the same time makes it hard on PSPs to provide more applications for new customers due to limitations on adhesions and fixation issues on many materials not tested or certified by the equipment manufacturer,” adds Singh.
Increased popularity in décor applications is a trend Mark Goodearl, senior ink product manager, EFI, hears of when speaking with customers. It is one of the reasons EFI ensures that its LED inks are GREENGUARD certified.
Wittenberg points out that the use of specific inks vary by region across the globe. “Some regions are more solvent/eco-solvent intensive while other are more latex and UV intensive. However, we are starting to see the growth in dominance of HP Latex inks across all regions given, not only its versatility with substrates, but the sustainable and environmental aspects of it too.”
Maxwell points out that generally there is consistent adoption across the country of all inks. “However, solvent inks tend to be more popular in coastal states like CA and FL due to the higher demand for wraps. The Midwest and Western states tend to have more demand for UV-curable due to manufacturing.”
“There is also increasing interest in substrate/ink compatibility as the range of substrates continues to grow in areas such as specialty paper, fabrics, and unusual canvases versus just being able to work with the basics such as vinyl and banner stocks,” says Wittenberg.
We discuss challenges and demands of ink sets for wide format digital printing below.
UV ink provides advantages in terms of flexibility and adhesion. Additionally, it offers instant cure—enabling faster turnaround times. Advancements in UV curing technologies, specifically UV LED, improve substrate compatibility.
Parsley expects growth in the UV ink market to continue. “This technology is finding its way into smaller shops that seek the efficiency of printing direct to rigid substrates.”
“The ability to print and not have to laminate makes UV inks an easy solution for corrugated signs and rigid boards,” agrees Singh.
It is important to note that UV ink’s ability to print directly onto a variety of rigid and roll substrates brings challenges. “In order to meet those challenges, today’s UV inks need to be extremely versatile, balancing flexibility with durability, color gamut, and jettability,” adds Hutcheson.
Parsley acknowledges that customers in the UV market want an ink that works on both rigid and roll materials. “They want a flexible ink that adheres to all substrates and be flexible when needed.”
Juan Kim, CEO, VALLOY Inc., says UV is dominate for its ability for fast curing on various substrates, noting that UV LED lamp control is easier compared to traditional UV.
Parsley sees LED inks eventually overtaking the UV lamp inks because the technology is safer and more affordable over time. “I believe the versatility of flexible inks will win out as the technology improves and the prices drop,” he offers.
LED inks address a core set of key applications at the heart of display graphics, serving a range of applications including point of purchase, décor, and out-of-home advertising. Additionally, speciality UV formulations are available for applications like roadway signage and industrial thermoforming, which is where Goodearl sees a growing demand.
Further, UV emits lower volatile organic compounds (VOCs) compared with solvent-based inks.
“UV inks are an acceptable replacement for solvent on roll to roll without the high VOCs,” comments Emery.
“Every solution provider wants inks that don’t smell like the traditional solvent printers, as well as less fumes, hazardous labels, and the ability to get better adhesion and quality printing from one ink technology,” says Singh.
Solvent, Eco-Solvent, Latex
Solvent-based inks are popular despite continued interest in UV. However, PSPs demand versatility, more environmentally responsible options, and faster dry times.
Padilla believes eco-solvent inks are still used more than UV and latex, though in the last few years major improvements to both technologies are closing that gap.
Both solvent and eco-solvent inks feature specific attributes that advance certain substrates and applications but cannot be universally used on all of them. Kristen McNamee, global R&D manager, digital print films, inks, clear coats and warranties, 3M Commercial Solutions, notes that it was assumed solvent/eco-solvent inks were being replaced by other chemistries, but it’s a slower transition than the industry anticipated.
PSPs look for improved environmentally responsible inks in solvent/eco-solvent category, according to Emery.
Many customers running eco-solvent inks are in the vehicle wrap industry and an important feature they like to see are minimal outgassing times—same day lamination—so they can turn jobs quickly, notes Padilla.
Kim says solvent/eco-solvent inks are used for better penetration to some polymers like artificial leather.
Eco-solvent is also a lower VOC alternative to solvent, but focused primarily on roll-to-roll applications. “Latex then became the alternative for eco-solvent because it is water-based and ‘greener.’ However, it not as durable and fade resistant unless using UV laminates or coatings,” shares Emery.
Water-based inks offer a sustainability advantage and are ideal for applications where human contact is a concern.
Eric Beyeler, global marketing manager, Ink Jet Inks, DuPont Image Solutions, believes multiple drivers, such as solution cost, workplace environment, and food regulatory reasons, strengthen the market request for water-based inks.
Emery explains that the green movement is driving the trend towards aqueous-based inks. “This importance grows for textile and indirect food applications wherever a human may come in contact with a product.”
There is an active focus on developing solutions for packaging, paper, and film with aqueous-based inkjet inks. “Paper packaging aqueous inkjet solutions are now available and the next challenge is print on film,” admits Beyeler.
McConnell agrees, noting that based on the role that packaging plays in digital wide format printing, “I wouldn’t be surprised to see development continue with aqueous ink due to the applications and pile height of the ink.”
Emery says aqueous pigment inks offer greater durability and improved adhesion to more non-coated substrates. “As ink companies develop next-generation water-based inks, the challenges are removing the water in the print system, achieving good adhesion, and getting overall increased durability.”
Jackman sees aqueous technology as a great potential opportunity for the future. “Achieving the same levels of performance, both in the printer and on the media is challenging for aqueous inks over that of UV or even solvent inkjet inks, but the environmental message of aqueous is relatively strong and will influence future development and decisions. Further, the latex inks market is also growing. Recent developments in this field have opened the industry’s eyes to water-containing inks.”
As UV and water-based inks have taken the spotlight, advancements include formulation of new kinds of aqueous-based UV-curable inks. StratoJet is currently working on this unique formulation. “Multiple testing has been done on UV system curable aqueous-based Inks. These inks would have tremendous advantages on print applications and a step towards a sustainable tomorrow. The performance and future subjects of this technology will be disclosed soon by StratoJet,” notes Singh.
Textiles are versatile, incorporating everything from soft signage to decor and apparel. A variety of ink formulations are used to print to textiles through direct printing, dye-sublimation (dye-sub), and transfer dye-sub.
Maxwell says textile inks are popular for several reasons. “Advancements in LED lighting and sign frames have increased demand for soft signage and backlits. Other areas are home furnishings and fashion.”
Randy Anderson, product marketing manager, Mutoh, says approximately half of all fabrics are printed with pigment inks. He explains that pigments have historically been screened onto fabrics and now producers and customers look to match the performance characteristics of this process using digital printing, including good lightfastness properties.
In specific applications like direct to textile, there is demand for extended gamut, high-performance digitally printable pigment inks. Pigment is usable for a wide range of textiles. Improvements in this type of ink make it a viable solution for short- and custom-run fabrics. “Customers desire improvements in performance and hand to make it comparable to other technologies like dye used to print fabrics,” shares Anderson.
“Pigment ink dominates for all kinds of textiles, but we need better color saturation. If we rely on precoatings for better performance, jettable primers need to be studied,” adds Kim.
Roll-to-roll pigment inks, including the latest offerings from DuPont Artistri, now deliver crock print performance and hand feel that the market needs, explains Beyeler. He says in direct to garment applications, new solutions for printing on dark polyester are emerging but unmet performance needs remain.
For dye-sub, Anderson feels the goal is wide gamut and quick transfer speeds. However, because it is dye it is sensitive to UV degradation resulting in fading in outdoor applications. “Many are looking for ways to expand the outdoor life of dye-sub products. The problem is dye-sub is not appropriate for natural fabrics.”
Ink sets have a significant impact on a PSP’s overall operation. For some, ink selection is based on a particular need. However, many look for versatility, quick dry times, and color vibrancy.
Sep2020, Digital Output