TEXTILES.ORG
Ink manufacturers strive to improve capabilities for printing on textiles.
By Janice Kleinschmidt
Look up the history of printing on Wikipedia and you’ll find a timeline that begins circa 200 with woodblock printing on textiles in China, followed by screen printing (1907), dye sublimation (1957), inkjet printing (1976) and ends with digital printing in 1993.
“Ends,” however, doesn’t mean advancements halted. Just last year, Sawgrass Technologies of Charleston, S.C., introduced a water-based pigment ink that binds—on a chemical level—to any type of precoated fabric without requiring steaming or washing and drying to fix the image. Mark Trimble, manager of product commercialization, calls pigment ink the hottest segment in textiles.
“I think that is the answer that people are looking for in textiles: that they can print a fabric using simple dry heat,” Trimble says. “People like easier printing. They don’t want to use water. They don’t want to steam an hour. They don’t want post-process waste.”
Also in 2009, Graphics One of Burbank, Calif., introduced its GO Salsa-TX printer that prints direct to fabric and paper for dye sublimation with water-based ink. The 64-inch printer integrates a Mutoh printer with a heat-process fixation system. “You get much better pop, much better color gamut and much better densities than with a solvent ink,” says Dan Barefoot, president.
On Oct. 27, 2009, Roland DGA Corp. of Irvine, Calif., introduced the world’s first inkjet printer/cutter developed exclusively for metallic silver ink. The ECO-SOL MAX ink previewed two weeks earlier at SGIA Expo, where it captured a DPI Product of the Year Award.
“You can print just the metallic silver ink by itself or combined with CMYK in a single pass,” says Robert Ozankan, senior product manager for Roland in the United States. The SOLJET PRO III XC-540MT printer comes with software that includes a library with 12 metallic colors and allows users to create custom metallics. The system also includes white ink.
“Generally, the challenge with white and silver is similar: the pigment particles that settle in the ink and the cartridges when it’s not printing,” Ozankan says. “We developed a new circulation system so it keeps flowing.” The metallic ink works best on fabrics with vinyl or acrylic coating or on Roland’s polyester-cotton blend glossy and satin canvas.
“In the solvent space, most advancements in the past years have been to increase ease of switchability and to decrease costs,” says Udi Nachmany, partnership and business development manager for HP Graphic Solutions Business. An HP upgrade allows users to switch from solvent inks to dye sublimation inks in less than 15 minutes.
“In the UV space, the main advancements in the past few years have been in increasing versatility and productivity,” Nachmany says. “This has happened in flatbed applications and in the billboard market, but is very relevant for textiles as well.”
According to Nachmany, the most meaningful advancements for Palo Alto, Calif.-based HP in recent years relate to latex technology. “It offers the advantage of enabling the same printer to be used for printing on a wide range of materials, for production of many other types of signage applications, without changing inks.”
Huntsman Textile Effects has introduced pigment inks with improved runability. Lyoperse GP comes in an eight-color set (CMYK, orange, red, green, and golden yellow) and can be used with or without pretreating the fabric. This quarter, the Basel, Switzerland-based company is launching Terasil Brite direct disperse inks “with the aim of offering polyester flag and banner printers a direct-print alternative to the sublimation process,” says Kevin Myers, global inkjet business manager. “When printed directly to polyester, it gives a much brighter shade than all other ink ranges, even without washing.” The ink comes in six colors and can be applied to polyester directly without a washing step. Huntsman also will launch an acid-dye-based cyan ink for the nylon flag market with six to eight times the outdoor light fastness of green/turquoise shades on the market.
Getting better
“About 10 years ago, the state of the art was what they called spray jet, which used these nozzles that came from the automotive paint industry, generally referred to as airbrush,” says Richard Severance, a chemist with 3M’s Commercial Graphics Division in St. Paul, Minn. “They were relatively low resolution and used for billboards, things viewed from quite a distance. Then we moved to the early-generation drop-on-demand, industrial-scale printers using Piezoelectric heads and solvent inks. The inks were primarily based on some combination with acetate solvents, what some call hard or aggressive solvents. That technology is still in use today. There’s much more sophistication in terms of the drop size and control over the drop, the number of nozzles assigned to any given color and the production of high-quality graphics; but the machines tend to be big and expensive. You find them primarily in large shops. They require industrial-type ventilation.
“Eight years ago, you started seeing the introduction of UV-curable ink printers, and a few years later, eco-solvents. As far as eco-solvents, there isn’t a real definition of what makes something an eco-solvent. What that term might mean is in the mind of the beholder. You would think it would mean they are more environmentally friendly, which may or may not be the case. They are easier to tolerate; they have a lower odor and are more pleasant to be around. Those mainly are in more of a mid-level price tier.
“High-output printers stay with the more aggressive solvents, I think primarily because of the faster drying; and it comes down to square footage per hour. The eco-solvents as a class are actually slower drying; that limits your output, and so it limits the market niche that they are appropriate for. But they’ve caught on, and any number of manufacturers offer eco-solvent printers in the $50,000 to $100,000 range.
“The UV printers came out about the same time, and the first ones on the market were large and expensive. They have advanced quite a bit over the years. The natural progression is better resolution and more nozzles per color. The price has come down. Some of the high-output printers are still very expensive, but you have seen some move toward more of a mid-tier $50,000 to $100,000 area. We’ve also seen developments in the UV light sources where any number of printers now have moved to LED UV lights. Along the same time came the development of high-output LEDs. The advantage of LEDs is a very long life in the tens of thousands of hours. They run cooler, allowing the printer to print on heat-sensitive substrates more easily.”
Next steps
“The next development could be on the ink side, although I believe from an ink standpoint we are in a very good position to meet the market demand in terms of fastness properties,” says Marco Torri, global sales manager for DuPont of Wilmington, Del. “What I believe is needed and is starting to happen is moving digital printing for textiles more from sample printing to production printing.” Faster printers will aid the adoption of digital textile printing.
Additionally, he notes, “the graphic market is becoming more and more interested in water-based ink and polyester material compared to last year, when everyone was focused on solvent ink. And pigment technology, which includes a binder, is probably the most versatile development. It allows you to print on a variety of fabric.”
“Graphics One is working with a pigment manufacturer,” Barefoot says. “What we are trying to do is to perfect a technology that allows you to print on fabric without a coating.” Graphics One, Barefoot explains, does business in Latin America, where coated fabrics must be imported, making them noncompetitive with fabrics made in Brazil and Colombia: “The long-term goal is to sell printers where you will be able to source the fabrics.”
Myers divides the future of digital textiles into two parts: the conversion of screen printing to digital applications, mainly in the apparel sector, driven by new machines and print head and ink development; and the development of simple dry-process printing of textiles on smaller machines in using pigment and disperse inks, driven by ease of process and demand for short runs and personalization of designs. “It gives business opportunities to entrepreneurial companies who wish to start digitally printing textiles without the need to have a huge processing plant to do so,” Myers says.
One thing is certain: Wikipedia’s printing timeline surely will expand.