Dye-sublimation (dye-sub) is a growing market best known for textile applications. Soft signage for trade show displays, polyester flags and banners for advertising, as well as short-run production of athletic apparel are a few of the applications from which print service providers (PSP) profit. Additional value lies in the ability of dye-sub inks to work across a variety of coated materials, including ceramic, steel, polymer, and glass.
The science behind dye-sub ink allows it to adhere to a variety of substrates while still maintaining a high-quality appearance. Many PSPs discover the benefits of producing applications on more untraditional substrates.
It’s a Science
To understand the capabilities of dye-sub ink, one must first learn the science behind it. “It comes down to ink chemistry, dyes, and surfactants used to make the ink, which allows for it to transfer and permanently bond to synthetic polyester substrates,” notes Syd Northup, inkjet division manager, Gans Ink & Supply Co.
Terry T. Sickle, VP, Hilord Chemical Corporation, adds that, “by definition, sublimation is a process that uses energy to force the solid pigment through to a vapor phase. Within the vapor phase, the dye is able to penetrate synthetic fibers. On other substrates such as glass, the dye has an affinity for the coating on the substrate.”
Dye particles bond well with polyester and polyester-coated surfaces. “Hard surfaces coated with polyester allow the ink to integrate into the material. Because dye particles react only to the polymers or polyester, the higher the polyester content, the more vibrant the output,” explains Dan Barefoot, president, Graphics One, LLC (GO).
“Since the dye is absorbed onto any polyester coating, substrates that can resist the transfer temperature are able to be coated, and are therefore receptive to dye-sub inks,” further explains Pedro Martínez, CEO, Afford Industrial S.A. “The dyes stay within the coating, offering both scratch and chemical resistance.”
“The quality in textile printing comes from dye-sub ink’s ability to transfer directly into the fiber of the substrate. Unlike other digital printing methods, it is not sitting on the surface of the material, but rather adhering to the actual strands of the fiber,” adds Mike Wozny, product manager, EFI.
Christophe Bulliard, commercial director global ink group, Sensient Imaging Technologies, explains that sublimation dyes—a sub-class of disperse dyes—fix easily within any sort of polyester whether in the form of woven/non-woven textile or in coatings, and that the process is governed only by the application of heat. “The use of dry heat, which is not possible with disperse inks, makes it possible to place the printed paper in contact of any substrate made of or coated with polyester, such as glass and aluminum, and ensures the transfer, thus creating a vivid image,” he states.
Catalina Frank, product manager professional imaging, Epson, offers an in-depth look at the chemical process that allows this to happen. “The solid particles contained in the dye change into gas when heat and pressure are applied during the transfer process at the heat press. They molecularly bond with the polymers in the substrate, be it polyester fabric or a pre-coated substrate such as plastic, ceramic, or metal. Since this is not a surface treatment, but rather a dye process, it produces output with a high-quality look and feel.”
New and Improved
Improvements in hardware affect ink advancements and vice versa. Printheads, speed of the ink jetting, and ink lay down all allow for greater substrate versatility beyond fabric. Hardware manufacturers are taking a good look under the hood of dye-sub print engines.
“The latest advancements in high-speed digital production printing require specialty formulations in order to maintain the highest image quality and reliability. Running production at speeds of two to three linear yards per minute means uptime is paramount and consistency and quality of output must be maintained throughout the run,” advises John Ingraham, director, product development, Sawgrass Technologies.
As Martínez explains, “the adoption of new, higher throughput printheads by machine manufacturers puts more expectations on the inks. The inks must feed printheads that have more nozzles, which fire faster.” This obliges ink manufacturers to modify the formulations.
Paul Fedorys, business development, Van Son Ink Corporation, attributes changes and innovations to pressroom chemistry. “The first dye-sub inks flowed at only 4,000 drops per second from an individual ink nozzle. Newer formulations currently allow 48,000 drops per second per nozzle at 192 feet of substrate per minute, while each drop meniscuses with the next in a micro-second,” he states.
“The popularity of dye-sub digital printing can be attributed to improved inks compatible with more robust, faster industrial printheads that integrate with the printers. Faster drying, better dye fixation, and improved dot gain control alongside improved RIP software also contributes to the popularity,” agrees Ruth Zach, marketing communications, Bordeaux Digital PrintInk Ltd.
Paul McGovern, marketing and promotions manager, Mimaki USA, Inc., concurs. “The raw materials for dye-based sublimation ink formulations continue to improve, offering a greater viscosity range of inks and chemistry performance to jet out of various printhead manufacturers’ products. Today’s printheads are configured to jet different drop sizes, waveforms, and speeds to allow for higher production printing, and can handle other textile inks like acid dyes, reactive dyes, and water-based pigmented inks.”
All About the Ink
Dye-sub inks have a considerable influence on the image quality and long-term stability of the prints. Improvements in old products and additions of new ones mean that these ink sets can be used in traditional signage and industrial segments.
Afford continues to develop its dye-sub ink portfolio. Its current focus is on the line of dot definition. The company is looking to achieve higher intensities and reduce transfer temperature by the use of different dyes.
Bordeaux offers dye-sub inks for direct and transfer inkjet on polyester fibers. By selecting the raw materials, Bordeaux guarantees greater stability on the printed media, and batch-to-batch consistency, making for vivid images at high speeds.
EFI’s biggest enhancement to its dye-sub ink set is faster drying. The eight-color ink set for the VUTEk TX3250r printer produces bright colors across a range of applications, allowing users to switch from a high-speed, high-volume four-color banner to eight-color retail graphics that require an increased color saturation.
Epson’s UltraChrome DS inks are formulated to produce high-quality color images and deliver excellent light and wash fastness. They are designed specifically to work with Epson’s MicroPiezo TFP printhead. Epson developed inks specially formulated for the printing technology itself, minimizing downtime from system failure.
Gans Ink’s Pyrojet series of sublimation inks are ideal for direct-to-fabric to traditional sublimation paper printing. Designed for all Epson piezo printheads, Gans Ink provides a variety of black, fluorescent, and specialty inks.
GO NeoTack ink offers an enhanced tack feature of the ink, which increases the tacky nature of some dye-sub papers. This provides crisp details and fine lines. The super black creates a rich, deep black standard, while the composite neon capabilities increase the normal dye-sub color gamut 30 to 40 percent.
Hilord inks are built for high-speed printers with high-resolution output. They are ideal for PSPs with large volumes, or those needing to print rigid or alternative substrates at high resolution.
Marabu North America provides its TexaJet DX-SHE water-based sublimation ink system, suitable for both transfer and direct printing. The substrate range includes polyester and nylon blended fabrics that contain at least 60 percent polyester or polyester-coated materials.
Mimaki recently introduced the SB-53 and SB-300 line. These inks offer a greater range of color gamut and dye brightness with a darker black ink formulation to achieve the richness needed for fabric printing. Mimaki focuses on both paper transfer and direct printing applications that require a stable ink to settle on the various pre-coated textile materials.
PrinterEvolution provides dye-sub inks for its Evo33 DS printer. The ink is produced in an ISO 9001 facility with strict quality control. Newest enhancements to the ink set include orange and violet expansion inks, delivering color metric accuracy.
Sawgrass addresses the need for speed with its Rheological Modified Inks (RMI), available in SubliM K+ and SubliM Direct K+. The technology enables superior color quality in terms of high color concentrations, fast drying time, and sharp dot formation. RMI ensures superior runnability and reliability for maximum uptime.
Sensient’s ElvaJet range of high-performance inks are developed for users requiring high productivity and reproducibility. Higher dye concentration allows savings of up to 40 percent in the ink volume applied to reach the same color space. Due to the high concentration of colors, Sensient’s ElvaJet inks are most commonly used in four-color configuration, compared to what were previously eight colors. This feature allows users to speed up the printing process.
At FESPA 2013 Valloy Incorporation launched Universal Direct Sublimation Ink (UDS), a new direct textile ink that prints on natural fibers with the convenience of being able to use existing dye-sub transfer-printing solutions—inkjet printers and heat fixation machines.
“UDS is an aqueous ink using volatile disperse dye encapsulation,” explains Juan Kim, CEO, Valloy. “The encapsulation technology is an organic-inorganic hybrid with multi-layer capsules. It features a core-shell structure, and each layer has a different function. Nanotechnology is applied by a bottom-up method in which the particle diameter starts small.”
Van Son’s polymer technology is the center of its dye-sub ink formulations, which enable greater adhesion to all types of substrates. The ink works on both natural and synthetic fabrics. Should the requirement be for printing on non-porous substrates, a layer of synthetic coating is applied in advance and allows the sublimation ink to adhere to the surface.
Van Son’s strict adherence to pigment particle size, negative ionization, and filtration prevent ink setting up in oxygenated and non-oxygenated environments, which eliminate nozzle clogging. Additionally, Van Son is part of a relatively new application in the textile industry that uses film positive dye-based inks for heat transfer.