TEXTILES.ORG
Innovations in digitally printed nonwovens.
By Janice Kleinschmidt
Bravo TV celebrity and maternity clothing designer Rosie Pope joined forces with Procter & Gamble to interpret summer 2011’s hottest trends for babies in a line of Pampers Limited Edition prints. Huggies introduced its own line of denim-look diapers. Both collections are a far cry from the ho-hum white diapers of yesteryear. More importantly, they illustrate innovations in digitally printed nonwovens.
“We have lots of examples of nonwovens in our conference room that people don’t believe when they see them, because the quality is very good,” says Benham Pourdeyhimi, director of the Nonwovens Cooperative Research Center at North Carolina State University’s College of Textiles. “The critical thing for direct digital printing is how the surface reacts with inks and how smooth that surface is so it looks like a film or paper, because that determines the resolution you get.”
“There’s an opportunity to get a smoother surface in a nonwoven because you are not making yarns, so essentially you have smaller fibers,” says Genevieve Garland, director of partnerships and innovation at NCSU.
As Pourdeyhimi explains it, nonwovens fall into the space between wovens and paper, so the trend has been to create more flexibility with higher resolution. The opportunity nonwovens present is the ability to control fiber size and, therefore, the density of the fabric. “We also have a very unlimited range of materials that we can pull from, so that gives you a portfolio of technology to create printable nonwovens—and that gives you the ability to define the surface,” he says. Functionality, such as antimicrobial properties, water repellency, breathability and UV protection, can be incorporated into the base material.
“You can engineer that fabric to be what you want it to be,” Pourdeyhimi says. “With typical wovens, you go through a secondary process to get the end result. In addition, with nonwovens, you don’t have fraying, so you can cut and shape the edges in any form. There are many different qualities nonwovens bring that we don’t have in wovens. There are many design factors we can bring in. You can texture the surface or emboss it. You can have materials that have a face that looks one way and a back that looks another.”
There’s also a weight savings. “Where you would use 6 ounces of woven, you might get away with 4 ounces in nonwoven,” Pourdeyhimi says.
Banner years
Freudenberg Nonwovens’ Evolon® has been around for about 10 years, but only entered the digital printing market within the last few years. “We always knew it printed beautifully,” says Terry O’Regan, business segment manager for the company headquartered in Weinheim, Germany. “Our fidelity is very good, almost a photo-like quality printing.”
Available in three weights (100, 130 and 170 grams), Evolon is used for banners, wall coverings, display stands and even artwork. “Most of the applications are using it to replace PVC, and most of that reason is environmental,” O’Regan says. “It has created a niche market in commercial banners for trade shows.”
Freudenberg offers Evolon with different finishes based on the types of inks customers use: PMI is for water-based inkjet or UV-cured inks, sublimation and laser printing. PMC is optimized for inkjet printing with solvent and eco-solvent inks. PMB is used for sublimation transfer printing and UV inks. Flame retardance can be added to any of them.
“I am not sure that there are any limitations compared to wovens,” O’Regan says. “The advantages are you don’t have a grain line, it doesn’t fray, it doesn’t have as much print-through, it’s lightweight and it’s very stable, so it doesn’t have to be backed to fit through a printer.” Because fewer edges need to be finished and frames to support them can be lighter, he adds, nonwovens offer a cost savings.
DuPont obtained five patents for spunlace technology from 1963 to 1970 and introduced it to the public in 1973. Then in 2009, the company introduced Tyvek® Vivia, a recyclable nonwoven particularly suited for UV-cured inkjet and screen printing.
“Most people, when they think of Tyvek, think of FedEx envelopes,” says Annette Kim, North America market manager for graphics. “With Vivia, now we are able to compete in the vinyl market.” A proprietary coating adds drapability, a velvety smooth texture and feel, thickness without added weight and better print quality than standard Tyvek because of its more uniform surface.
“We have specifically targeted the banner market, the large-format arena,” Kim says, noting that Vivia is available up to 116 inches wide. “We are positioning this product against anywhere from 13-ounce to 20-ounce vinyl. At 8.9 ounces per square yard, many times you are reducing the weight by more than half.”
Although it is not flame retardant or launderable, Vivia costs less than many woven textiles. Kim says the price is competitive with a good-quality vinyl.
Banner Creations Inc. of Minneapolis, Minn., uses nonwovens daily, primarily as liners, but also has been printing on nonwovens for about 20 years. “We are always looking for something new for our customer,” says Nora Norby, owner and president. “In the past, we did quite a few banners on Drop Screen [a nonwoven product of France-based Procédés Chénel International].” Now she uses Freudenberg’s Evolon and Lutradur® and Dupont’s Tyvek for dye-sublimation printing.
“Drop Screen changes their colors year to year, and one museum that we did a lot of banners for did not like the new colors,” she explains, adding that Drop Screen also incorporates Fiberglas, which can be a deterrent.
“The benefits for printed nonwovens is they offer a different look,” Norby says. Much like woven fabrics, she notes, costs vary considerably, ranging from $1 a yard to $25 a yard.
Finland-headquartered Ahlstrom Corp. offers nonwovens for aqueous- and solvent-based inkjet printers, featuring either a “fibrous aspect” (for light diffusion) or a “textile touch.” With high-print quality, dimensional stability, drapability, and fire-retardant substrates, they can be used for indoor banners, booths, exhibition panels and light-box displays. “All of the banner materials are made on a wet-laid nonwoven line, similar to paper. But unlike paper, which uses almost exclusively wood pulp, our process allows us the ability to use high levels of synthetic fibers, which provides dimensional stability, strength and a more textile feel,” says Douglas Benton, product development manager for Ahlstrom Nonwovens in Windsor Locks, Conn.
Technically speaking
“A nonwoven fabric isn’t that much different from a woven or knitted fabric, in my opinion,” says Rene Wolferink, application specialist for digital textiles at Stork Prints, a Netherlands-based manufacturer of printers and inks for digitally printing fabrics. “Just the way it is created is different. Some nonwovens are created because of simple technical aspects, such as dimensional stability in length and width, that may not be possible in a woven or knitted fabric. What makes a fabric printable or nonprintable is the type of fiber used.”
However, in cases where it is necessary to wash a fabric after printing and fixation, woven fabrics claim an advantage. “Some nonwovens are just fibers that are lightly bonded that could easily unbond in a washing cycle,” Wolferink notes.
Pourdeyhimi agrees that the need for launderability limits the choice of nonwovens. “Agitation and water in a washing machine disturb some of the bonding in chemically or thermally bonded nonwovens,” he explains. “Short fibers will come out.” The most durable nonwovens are spunlaced (see “Oh, what a tangled web we don’t weave”) with continuous filaments. “Evolon can be washed 200 times and it will not fall apart,” Pourdeyhimi says.
Ahlstrom’s nonwovens are not launderable, but are intended for use within 12 months and should be used in an environment without large temperature and humidity fluctuations. “They could last an indefinitely long time if they are handled well and do not see weather,” Benton says. “Rain, dirt, long-term exposure to UV rays, and excessive mechanical forces would be limiting factors.” They are certified as flame-retardant, and the company is developing new banner grades with needle-punch technology for outdoor use.
National Nonwovens of Easthampton, Mass., has been offering printable nonwovens for more than 10 years. “Digitally printed nonwovens are far superior in terms of print quality, giving you a consistent, smooth surface, enabling 3-D images, improved strength, edges that will not unravel and cost efficiency,” says Conrad D’Elia, director of research and technology development. “Our customers have made the transition to nonwovens because of consistency of the surface and the ability to create a 3-D image. The synthetic fibers allow the ink to stay on the surface, producing a superior image versus a woven where the fiber absorbs the ink.”
Creative thinking
For all their potential, nonwovens still claim only a small portion of industrial fabrics applications. Historically, they have been grounded in disposable products, such as diapers, wipes, medical gowns and face masks. “In the more traditional textile market, nonwovens are used for interfacings, interiors, carpet backings and batting or insulation, but they are making the transition to more outer fabrics,” Garland says, offering by way of example the growing use of reusable grocery bags made from nonwovens.
And since the disposables market is still a huge one for nonwovens manufacturers, they may not need or want to invest heavily in going after durable product markets. However, Garland notes, “People are working to make nonwovens more durable. They are discovering new applications and enhanced performance that was previously thought not possible for nonwovens.”
Meanwhile, nonwovens remain untested ground for many fabric graphics companies.
“People know what they know, and they don’t know what they don’t know,” Pourdeyhimi says, noting that those in traditional printing businesses are accustomed to working with certain fabrics. “If those work for them, they won’t be looking for a new solution.”
But businesses that want to expand their horizons may want to consider adding nonwovens to their repertoire.
“There’s no reason why you can’t use nonwovens in many applications,” Pourdeyhimi says. “Some of them can be used for seat covers, home furnishings, bedspreads, tablecloths. There’s a lot of potential.”
“Our first printable request was for banners, then printable rugs, and then, digitally, to be able to laminate the printable base on a canoe,” says Michalina Centofanti, vice president of National Nonwovens.
“Our customers’ markets are continually expanding based on the fact that they can produce such vivid images,” D’Elia notes. “The main trend we see is growth and open-minded ideas of where these products can be used or created.”