New inks allow versatile printing
Ink manufacturers are delivering a variety of products to meet the increasing demand for textile printing.
By Holly O’Dell
Within the last 12 to 18 months alone, ink manufacturers have introduced a variety of dyes and pigments suitable for digital textile printing. The inks’ content and performance continue to improve thanks to companies’ ongoing commitment to R&D and evolving technology. New types of ink deliver unique opportunities for print shops to expand their markets and for end users to create a fabric-based product to help them stand out from the pack.
In creating its newest ink, called Sepiax, Graphics One in Burbank, Calif., listened to its customers’ desire for a green alternative. Sepiax is a pigment ink comprising about 70 percent water. “We have seen a lot more people who want to print on fabrics without eco-solvent or solvent inks,” explains Dan Barefoot, president of Graphics One. “That way, you do not have any issues with government agencies [related to environmental concerns] and you still get a beautiful image.”
Sepiax has been designed to print on nearly any substrate using printers on the market with pre-heaters. What’s more, the substrates—which, for textile printing, can range from vinyls to cottons—do not require a coating. Using this ink, end users are creating products for the interiors market, such as fabric wallpaper and custom upholstery fabrics, as well as flags and soft signage. In addition, Sepiax is warranted for outdoor use for up to three years.
The call for green was at the forefront when Palo Alto, Calif.-based HP introduced its HP Latex inks in late 2008. “We perceived that customers wanted to have the durability of a solvent ink on diverse materials, along with the environmental benefits of water-based inks,” says HP product manager Tomas Martin. “We listened to their needs and provided one ink that prints on a variety of materials with high quality and high productivity.” Furthermore, the inks produce odorless prints (aside from any odor from the substrate itself) and no special ventilation is required in the print shop.
The HP Latex inks, which work on the HP Designjet L25500 printer and HP Scitex LX600 and LX800 printers (the latter of which was introduced last year to work with porous textiles, such as unlined flags), are water-based inks compatible with coated and uncoated polyesters and are ideal for indoor textile end applications such as wall coverings, soft signage, event banners, architectural decorations for corporations and light boxes.
Versatility ranks as one of the major capabilities of the HP Latex Inks, according to Martin. “Another characteristic is that the medium is printed in one step,” he adds. “You don’t have to print it on a paper and transfer it to a textile [as you would for dye sublimation]. You print right on the fabric.” In addition, the textile is completely dry when it comes out of the HP Designjet L25500 printer or HP Scitex LX600 and LX800 printers, which are built with two heat zones for drying and curing.
Driving forces of development
Understanding clients’ needs is a highly influential factor in developing textile-compatible inks. “We produce inks based on customer demand but also by selecting market sectors where there is demand and potential for new and innovative solutions to offer value to OEMs and end users,” says Tim Phillips, marketing manager for Xennia Technology Ltd. in Letchworth, UK.
To that end, Xennia’s two most recent ink offerings address what’s been missing in the market. XenInx Amethyst is a water-based reactive dye ink that comprises CMYK with added spot colors to allow an extended color gamut, enabling production of vivid prints on cottons, wools or silks for end uses in fashion, furnishings and bed linens.
Textiles printed using XenInx Amethyst—like other reactive inks on the market—require a pre-treatment and need to undergo steaming to affix the ink to the fabric, followed by a comprehensive washing procedure to ensure the removal of unfixed dye.
Meanwhile, XenInx Moissanite is a pigmented UV-curable inkset specifically designed for outdoor applications, such as soft signage, flags and banners. When applied to a white textile, the inkset is printed and cured inline with no other processing requirements. “To print on a darker fabric, a pre-treatment is required to control the absorption of white ink to give the required opacity of the white background,” Phillips explains.
The inks differ from their predecessors in a few important ways. “They have been specifically designed for long-run industrial applications where color performance and reliability are key,” Phillips says. “They have been tested under the harshest conditions to ensure long-term print performance in the field.”
Some manufacturers continue to refine their development of water-based disperse/dye-sublimation inks because of polyester’s multipurpose nature. “A lot of polyester is being used in the market because it mimics so many other kinds of fabrics, whether it is satin, silk, matte sheens or glossy looks,” says Mike Compton, national sales manager for Mimaki USA Inc., Suwanee, Ga., which has developed the SB 200 series of disperse ink for its TX400-1800D series of printers. “People are moving away from printing on vinyl because it stays in the landfill forever, and many of today’s polyesters are recyclable or made from recycled items.” The printed polyester, particularly for flags and banners, can be used outdoors as long as it is heat fixed and washed to remove unreacted dye.
In addition to the disperse ink, Mimaki USA is in the process of developing reactive and acid dyes for its TX400-1800B printer. In October 2010, the company started shipping a new eco solvent-based silver ink. The ink, which was released primarily for packaging and labeling, works on certain fabrics (such as canvas-type materials) but does tend to produce metal flakes on the cloth.
Another factor driving new inks is the development of new printheads. DuPont™ Artistri®, for one, is expanding its base of disperse textile inks based on such changes. “Different kinds of printheads require different physical characteristics, such as viscosity and surface tension,” says Patrick Foley, global product manager for DuPont™ Artistri® textile inks. “These inks are adjusted and reformulated to work reliably on a Spectra printhead by forming drops properly and jetting reliably, while at the same time providing end-use performance, color and durability on fabric.”
With most disperse inks on the market today, the accepting textile still requires a coating or pre-treatment. “There are thousands of kinds of polyester fabrics out there, and they all act a little bit differently to inks,” Foley explains. “Some fibers are smooth on the outside, and when you put an aqueous drop in them, the ink tends to run down those fibers. Then there are other polyester fibers that are rougher, and the pre-treatment allows a nice finish from one color to another.”
Understanding ink compatibility
Despite the increased versatility of inks used for textile printing, not all of them are created equal—nor are the fabrics they work on. “There are multiple types of textile substrates, and each one interacts with the ink in a different manner,” says Nitin Goswamy, president of A.T Inks with U.S. offices in Charlotte, N.C., which is preparing to launch a line of solvent sublimation inks. For example, organic fibers behave differently from synthetic fibers—not to mention that many textiles are coated. “When you look at the possible number of combinations of textiles and coatings, it is very hard to formulate an ink that would be able to work well on all combinations.”
In order to achieve ideal results, Goswamy adds, it is crucial to use an ink that is optimized for a certain textile. When choosing inks and a printing system, print service providers should first consider what market they’d like to serve (e.g., soft signage, garment printing, flags and banners) and order the appropriate equipment and accessories from there.
Additional questions to ask the manufacturer or third-party seller may include:
- How much testing has been done with the printer and ink on the media/graphics applications I plan to produce?
- What is the warranty?
- What support resources are available?
- What is the total cost of print—not just of the ink or printer, but in terms of reliability, future maintenance, etc.?
With new inks on the market today for digital textile printing, print shops—and, in turn, their customers—have many choices for a host of applications. Inks will continue to become more versatile, from color gamut to eco-friendly content.
The future also holds even better performance characteristics. “The really exciting area is function materials for coatings,” Phillips notes. “Inks are being developed to coat layers, such as dirt repellent, water repellent, anti-microbial, textures, feels, mosquito repellent and so on.”
