Thinking About Ink

The history of ink began in China about 43 centuries ago, while the story of inkjet can be traced to an obscure patent issued in the UK in 1867. The wide-format inkjet systems that interest Big Picture readers began to emerge in the late ‘80s; since then, both the printheads and the inks that flow through them have evolved, expanded in capability, and permitted inkjet to address a multitude of new applications.

Today’s users are asking inkjet inks to do more and perform at a higher standard. In response, ink chemists are refining their processes, purifying their ingredients, and developing new formulations. Printheads impose their own requirements on the inks that pass through them. Typically, inkjet formulations need to have very low viscosities compared with inks used in analog processes such as screen printing and lithography, and pigmented inks must use more highly refined particles. With inks for piezo heads, preventing air infiltration improves shelf life and helps to ensure that the ink channels aren’t blocked during printing, causing jet-outs. Ink manufacturers are continuing to respond to the requirements and challenges presented by the technology while developing new solutions for growing market opportunities.

Those new applications, and the understandable desire that ink manufacturers have to address them with a variety of ink technologies (including water based, mild solvent based, strong solvent based, UV curable, and more), are driving a number of key trends in ink technology development today.

Players and Partnerships Emerge

One key trend is growth in the number of ink manufacturers formulating products for the inkjet market; at least six of the world’s 20 largest ink producers offer inkjet products, including Sun Chemical, Inx Digital, Fujifilm North America, SICPA, Wikoff Color, and Royal Dutch Van Son. As conventional print technology users begin to recognize the advantages of inkjet processing for developing prototype and sample products and for short to medium runs, they are adopting inkjet production methods and seeking inkjet ink and coating chemistries.

Because many of these companies do not have the inkjet expertise needed to integrate inkjet printing systems and formulate inkjet chemistry, they call on companies that do. Behind the products that many ink suppliers bring to market is the work of other companies with components and formulation expertise. Examples include the chemistries of BASF, the photo-initiators of Sartomer in UV-curable inks and coatings, and the dispersants and primer coatings of companies like Sensient, DuPont, and Lubrizol that are becoming key to the growth of digital textile printing. These behind-the-scenes suppliers of inkjet ink components and formulation expertise are also growing, driving further innovation as inkjet adoption expands.

Textiles on the Rise

Market analysts have been predicting that the digital printing market in North America would explode for more than two decades, but now it’s happening, and not just in the soft signage and direct-to-garment segments that are already established.

Last November at the ITMA show in Milan – by far the largest tradeshow for the textile manufacturing industry – pigmented inks were among the most talked-about product introductions. These new formulations provide softer hand, improved light- and wash-fastness, and wider color gamut than previously available formations.

ITMA pigmented ink launches included Kornit’s NeoPigment Pure process-color inks; the Velvet Jet line from Bordeaux Digital Print Inks, promoted as a universal ink set for all fabrics; MTex Solutions’ inks printing on the firm’s rebranded line of Mimaki printers using Ricoh Gen5 printheads; Durst’s Alpha Ink P, marketed for a wide variety of textiles; and a new line from MS Printing Solutions, designed to print pretreated fabrics through Kyocera KJ4B printheads. It has also been reported that Inx Digital is due to launch a pigmented aqueous ink for high-volume textile printing.

Dye Sublimation in Action

Both direct inkjet printing of textiles with disperse dyes and indirect transfer printing of textiles and other receptive substrates with related dye-sublimation inks continue to grow in many applications, including flexible signage and apparel. Dye-sub inkjet transfers also decorate nameplates, mugs, and promotional and personalized products. Among the product introductions at ITMA, Mimaki introduced fluorescent dye-sublimation colors for use on its dye-sub machines, including a new 10.5-foot printer using Panasonic printheads. And, recent months have seen three new Epson SureColor dye-sub printers featuring high-density black ink; the launch of Roland’s Oeko-certified Texart dye-sublimation inks and printer; EFI’s acquisition of UK dye developer Rialco (and hints that two entry-level machines can be expected this summer); and entry-level and high-speed models from Mutoh offering up to eight colors. Durst and partner Van Straaten have developed what is likely the world’s largest dye-sublimation machine at 16.4 feet; the printer uses water-based inks and was on display at FESPA 2016 in Amsterdam.

The massive potential of the dye-sublimation market is also evidenced by recent multimillion-dollar moves among international manufacturing giants. The 2015 merger of Kiian and J-Teck3 and their subsequent acquisition of Sawgrass Industrial created the world’s largest digital sublimation ink consortium, the JK Group – that consortium was quickly scooped up by the Dover Corporation. With over $7 billion in annual sales, Dover now controls a number of key inkjet technology providers, including Markem-Imaje for marking and coding inkjet and MS Printing Solutions for textile printing.

In Support of Sustainable Printing

Inkjet ink formulation is also becoming cleaner and greener, and the growth of alternate ink chemistries will be part of that trend. UV LED curing for the graphic arts, as well as for tag and label inkjet printing, will continue to grow. EFI Vutek and Jetrion, for example, have adopted UV-LED curing as their preferred solution to minimizing environmental and workplace exposure hazards. The advantages of LED curing are helping to drive its broader adoption – instant start/stop without shuttering, longer useful bulb life (up to 10 times longer than conventional mercury bulbs), low and efficient energy usage, focused peak irradiance with minimal energy waste, low-temperature operation that allows heat-sensitive materials such as polypropylene to be printed successfully, and removal of mercury disposal concerns.

Through our research at my company VCE Solutions, we estimate that LED curing has grown at about 30 percent per year for the past five years, and we see no sign that the pace will slow. Unlike mercury bulbs, which have multiple points of irradiance across the UV spectrum, UV LEDs peak at specific wavelengths and thereby require ink formulations with photo-initiators that perform at those points on the spectrum. As manufacturers of UV LEDs bring systems that are increasingly more focused and powerful to market, we may even see faster LED printers and fewer ones using nitrogen blanketing.

We will also likely see more UV-curable inks using evaporative solvents or water to reduce both viscosity and the thickness of the deposited, cured ink film. Durst demonstrated such a product at FESPA 2016 with its WT inks, described as reactive water-based technology that substitutes water for much of the monomer used in traditional UV inks to achieve a low enough viscosity for jetting.

Other ink companies, including Inx Digital, are formulating water-based and some solvent-based UV hybrid inks, some of which are being promoted as low-odor and low-migration solutions. We expect to see more ink companies using water or solvent to reduce the amount of monomers in their inks, particularly those that cause regulatory concerns.

We also expect latex technology to grow and advance. HP’s third-generation latex inks with its Optimizer primer are now used widely in signage and graphic arts color printing. Other OEMs have introduced models using latex inks, including Mimaki’s JV400LX and Ricoh’s Pro L4100 series, and third-party latex inks are now available from a number of suppliers including STS Inks and Bordeaux. While latex inks expose users and the environment to minimal hazard, making them particularly useful for environments where customers will be in close proximity to printers, they do require more heat (and energy) to evaporate the water and solvents and dry the prints.

Manufacturers of textile inks and processing systems are eliminating the pollution from fabric washing effluent in a number of ways. One is through further development of sublimation transfer printing, in part because it does not require post-print wash processing. Even direct inkjet printing of disperse dye does not typically demand post-print washing when used for indoor soft signage. A number of textile processing manufacturers have developed post-print washing systems for acid, reactive, and disperse dye-based inkjet fabric printing that recycle and minimize wash water and effluent.

Application Specialization

Finally, as printer OEMs continue to look for market opportunities beyond traditional wide-format uses in outdoor advertising and interior displays, ink technology will follow into new applications. Examples like the ceramic tile industry, which was entirely a screen printing application in 2000 when the Spanish company Kerajet introduced its first ceramic tile printer and is now about 60 percent inkjet, will encourage more development along these lines. Already, inkjet ink formulators have designed inks for flooring, metals, wood laminates, glass, and a host of plastics beyond the rigid and pressure-sensitive materials used for display and advertising purposes.

In addition to textiles, packaging is an increasingly eagerly sought after market by both machine and ink developers, as the current market share of inkjet remains low and the volume of products printed is extraordinarily high. Look for this to be among the most dominant themes at drupa 2016, the world’s largest printing exposition, to be held May 31 through June 10 in Düsseldorf, Germany.

Read more from our April 2016 “Inspired Interiors” issue.