By Melissa Donovan
With another year behind us, it’s time to look at the state of ink in wide format digital printing. Certain topics continue to be cause for discussion, while others are less impactful than they once were. For example, UV-curable and UV LED inks’ versatility continues to be relevant, especially in light of digital printing’s move into manufacturing environments.
This article takes a different approach compared to previous iterations. Segmented by application—textiles, traditional signage, pressure-sensitive based, and pre-manufactured and packaging materials—we explore how each application category’s preferred ink has evolved, where the demand for this type of ink is coming from, and why the inks mentioned are ideal for the specific application.
Textile-based applications include garments, décor, and soft signage. Depending on the type of fabric used and what it will be manufactured into, several preferred ink sets are used in textile-based applications.
According to Nick Buettner, director of global technical sales, Advanced Color Solutions, the overall trend in this space is increased stability. “Meaning more reliable operation without ink supply or printhead issues. The future is for these technologies to include more direct dispersion to textile and hopefully the ability to do so without extensive treatments to the fabric.”
Dye-sublimation (dye-sub) water-based ink is used for digitally printed textiles in fashion and décor. “Many manufacturers of fashion clothing, accessories, and home goods look to onshore their textile printing production with dye-sub water-based ink to reduce lead times, lessen minimum order requirements, improve quality control, and become more responsive to short-lived fashion trends,” says Susie Mendelssohn, Triangle global sales and marketing manager, INX International Ink Co.
The dye-sub process is also attractive for soft signage producers. “For soft signage, dye-sub is becoming the number one choice. It is less complex and overall less expensive,” admits Jack Papaiacovou, VP/GM, Hilord Chemical Corporation.
In recent years, dye-sub has advanced in color and visual quality. “For true, two-sided textile printing applications the preferred ink is dye-sub. It is necessary because the ink becomes embedded in the fabric,” explains Larry Salomon, VP, wide format, Agfa Graphics.
Hasan Bagli, sales manager special applications, OCP, believes it is because dye-sub ink creates vibrant colors using less ink due to high dye concentrations.
Pigment-based ink is also popular for textile printing, specifically of garments, where the fabric versatility is vast from cotton to velvets and silks. “For most other fabrics besides polyester, dispersed pigment is the current leader. Minus some new technology making it easier to dye natural fabrics, dispersed pigments continue to improve,” foresee Randy Anderson, product manager, dye-sub and direct to textile printers and David Conrad, director of sales and marketing, Mutoh America, Inc.
“Advantages of using pigment inks include fabric independency, required pre- and post-treatment is minimal, and light fastness is superior,” suggests Nitin Goswamy, president, A.T. Inks.
The improvements in washability and hand are other reasons, according to Juan Kim, CEO, Valloy Incorporation, that pigment-based ink remains prevalent in the production of garments.
“New developments with pigments and binders tailored specifically to textiles give chemists and formulators better raw materials to work with and now some very good pigment textile inks are available,” shares Heather Rockow, business development, Kao Collins Inc. The company’s pigment ebeam inks, due to the ebeam process, are ideal for use in clothing where ink migration is a concern.
Acid dye ink is an option for printing to fabrics that may be subjected to outdoor elements. “For garments and décor, we see great usage of acid inks. They provide superior outdoor longevity compared to dye-sub ink,” points out Papaiacovou.
Outside of the traditional practice of using dyes and pigments for textile printing, John D. Peterman, executive VP sales and marketing, Big Systems, LLC, argues latex ink impacts this market segment. “With an 11 percent growth in soft signage expected to continue through 2020, the demand is there. With the advent of new durable, printable textiles, latex-printed materials provide great cost savings and durability.”
“When latex ink was initially launched, it was mostly used for banners, wraps, and retail signage; but improvements in ink technology, such as improved waterfastness and scratch resistance have continued to open new markets for latex,” agrees Sandy Gramley, AMS category manager, latex supplies, HP, Inc.
As for demand, the manufacturing process for textile-based applications is changing. “For apparel, for example, clothing companies need the type of flexibility that you typically see in fast fashion, where designs are created and brought to market in weeks instead of months. From an ink perspective, the durability and vibrancy of our inks are key in those applications,” explains Stephen Emery, VP, ink business and new business development, EFI Inkjet.
Amy Hohenadel, laboratory manager and Holland Weber, marketing and design coordinator, Polymeric US, agree that new applications are driven by industry trends in addition to customer requests. “New avenues for dye-sub, weatherable digital inks/coatings, and inks for markets that were screenprinted and combination mercury vapor/LED curing are all projects that are the focus of Polymeric’s research and development laboratory.”
Traditional signage such as banners, trade show graphics, and outdoor signs were some of the first applications produced on digital printers. Because of this, they utilized several iterations of ink sets from solvent, to eco-solvent, latex, and UV.
Within all of the applications mentioned in this article, Mendelssohn says traditional signage is probably the oldest, dating back to the 1990s. “Inks used at that time had an extremely high solvent content and durability.”
“In the past inks were made with harsher organic solvents and then moved to mild solvents and now most of them are made with eco-solvents, which are safer for the environment and formulated to perform the same or better than inks made in the past using full solvents,” agrees James Schall, founder, Budget Inks.
Josh Hope, senior manager, 3D printers and engineering projects and Tommy Martin, product manager, textiles and apparel business development and marketing, Mimaki USA, Inc., explain that eco-solvent and solvent inks still present the most versatile opportunities for general graphics intended for indoor or outdoor use. “The introduction of expanded ink colors such as orange and light black combined with improvements in substrate compatibility create an increased demand.”
Durability in terms of wear and tear and fade resistance is important for any ink set used in traditional signage. Anderson and Conrad believe eco-solvent ink is primarily used in applications like banners, trade show graphics, and outdoor signs because of this.
“The color gamut on eco-solvent remains most encompassing to give better depth and color clarity to images printed for indoor and outdoor applications. The durability and color vibrancy of eco-solvent ink remains superior for installations where high traffic may be present or where detailed imaging is required,” they continue.
Latex is commonly considered for its “green” attributes in addition to substrate diversity. “Concerns about volatile organic compounds (VOCs) and related odors and potential health risks cause many to shift to either latex or eco-solvent ink. The signage market will continue to be anchored in a combination of both latex and UV based on sheet applicability across the largest variety of substrates,” shares Dan Johansen, marketing manager, wide format solutions, commercial and industrial printing business group, Ricoh USA, Inc.
Similar to latex, as pointed out by Johansen, UV-curable and UV LED ink offers limited VOCs and a wider range of printable substrates. Becky McConnell, product marketing manager, Fujifilm North America Corporation, Graphic Systems Division, sees traditional signage providers turning to UV printing to address the faster turnarounds demanded by brands and clients.
“UV inks of today are increasingly resistant to UV sunlight and in many cases go without additional lamination. UV-curable inks continue to evolve with formulations allowing for greater flexibility and adhesion to multiple substrates,” adds Mendelssohn.
The demand for UV ink used in the creation of traditional signage is based on “fast turnarounds and short run lengths due to versioning and smaller markets. The ability to print and immediately cure offers the benefit of getting to finishing and fulfillment as quickly and efficiently as possible,” explains McConnell.
Thinking ahead, Buettner sees the ingredients of the ink sets used in this market segment to migrate away from regulated toxins and chemicals.
Sticking To It
Pressure-sensitive applications include wallcoverings, vehicle wraps, floor graphics, and window graphics. UV and latex inks are used in this printing process, namely because they work well with thinner, somewhat more difficult substrates that make up the final product while still offering a quality appearance. Eco-solvent ink is also still used.
“For decals, stickers, and labels, supported film or paper features different shrinkage with a base material in most cases. UV LED ink with its low level of heat generation is ideal for this kind of application and starting to dominate the market,” suggests Kim.
Peter Saunders, business director – digital, Sun Chemical Corporation, shares that most of the inkjet inks the company sells today for pressure-sensitive applications are a wide spectrum of conventional UV-curable, but there is significant growth in UV LED.
UV and latex are used for the majority of pressure-sensitive based work according to Johansen because of their immediate finishing capability, options for ink flexibility, and large color gamut. “The biggest difference is the significant move away from solvent or even eco-solvent to UV or latex inks because of their quick dry capabilities as well as the ink technologies’ ability to support the best balance of color, substrate flexibility, and color longevity.”
Peterman addresses latex’s quick dry capabilities specifically. “The ink is cured as it exits the printer and can be finished or laminated immediately. Decals and stickers can be printed full bleed and contour cut without waiting for curing and outgassing, and won’t suffer from edge curl and shrinkage. The inks are much more scratch resistant as well.”
Other water-based technologies are slated to have an influence in this segment. Dr. Simon Daplyn, marketing manager, Sensient Imaging Technologies, shares that some water-based technologies are emerging. At Sensient in particular, the company is developing aqueous solutions for non-porous materials. “This technology limits VOCs and is able to form a thin film of ink, giving maximum color benefit.”
From printing directly to furniture or building supplies and promotional items like golf balls, pre-manufactured materials maintain a growing presence in digital print. Packaging applications like corrugated and flexible also hold a large stake.
UV flatbed digital printing positively impacts the promotional and awards production market. “The ability to add color and to mass customize objects enable promotional product printers to take on short run/custom color jobs that were not financially feasible using screenprinting methods or even possible using engravers,” share Hope and Martin.
“Because of UV ink’s ability to have both strong adhesion and flexibility, it expanded options for pre-manufactured materials and packaging materials. UV’s ability to be cut and finished, allowing for the inks to flex around the edges, makes it ideal for packaging and prototypes and short-run packaging production,” recommends Johansen.
For packaging production in particular, Lily Hunter, product manager, textiles and consumables, Roland DGA Corporation, points to faster curing times and white and gloss inks as specific benefits. Anderson and Conrad explain that UV LED provides the ability to print using clear varnish, which provides a raised surface look that mimics textures.
Although UV ink is considered somewhat safe, for packaging that is directly in contact with food, water-based ink sets are being studied closely. “In packaging materials, I think the systems are not yet mature, but it seems water-based inkjet inks will be the ink system of the future,” foresees Pedro J. Martinez, CEO, Afford Industrial.
“Specific to food packaging, many ink companies produce low migration UV and LED inks. However, as government regulations become stricter, ebeam inks will become the ink of choice. Using ebeam inks and ebeam curing, food packaging producers can eliminate risks associated with photo initiators, migration, and VOC emissions,” adds Rockow.
One other application in this category is those produced via thermoforming. Graphics can be printed digitally and then thermoformed into a sign or automotive part if the correct ink is used. Javier Mahmoud, VP of sales and marketing, CET Color, says the company may release a flexible UV ink because of the demand.
Ink vendors realize there are many applications that traditional print providers can now offer customers and want to offer a versatile ink set. Non-traditional print environments—like manufacturing facilities—also look for flexibility in ink. However, it is difficult to create a universal ink, so chemists continue to tweak and advance existing formulations based on applications.
“Choosing the right ink for the application is critical to accurate and consistent color managed printing,” stresses Salomon. Agfa invests significant time, energy, and research into establishing an ink product line that is consistent and reliable to meet customers’ printing needs.
Fujifilm constantly develops new and improved ink formulations for specific applications through various means of printing. The team works with user feedback and industry experts to anticipate the needs of the market to develop products that advance the industry, according to McConnell.
HP works closely with its customers to improve existing latex ink and understand what new directions they would like to take the technology.
At INX, ink formulation previously revolved around specific printheads and printers. “Now, due to the variety of applications in the market, we tend to develop to applications and then adjust as needed for specific printheads and printers,” shares Mendelssohn.
“Polymeric is unique in that it has the capabilities of turning customer requests into products in a relatively short period of time. Our chemists have full ownership of projects from beginning to end instead of going through a multitude of departments to finish an ink system. This shortens development time and gets product to market quicker,” say Hohenadel and Weber.
The substrates and requirements of ink performance are so different, admits Saunders, that Sun Chemical has separate research and development groups working on the needs of each application. “The common factor is that the inks all need to jet and function reliably, so the understanding we have gained of the influence of ink chemistry on the physics of inkjet printing is essential in all ink development.”
Striving for Efficiency
Textile based, traditional signage, pressure-sensitive based, and pre-manufactured and packaging materials are broad headings with hundreds of applications found in the scope of digital printing.
The ink sets vary but as advancements in chemistries progress there is an important theme across all of the applications. Whatever is printed, customers want finished products quickly. Ink sets must offer outgassing or drying capabilities that do not inhibit the production cycle in any way, while also providing a level of quality the customer is accustomed to.
Apr2018, Digital Output