By Melissa Donovan
Many textiles are printed with water-based ink but depending on the chemical configuration water-based ink is also utilized for printing to rigid or semi-rigid materials in the creation of packaging or industrial decoration applications. While UV-based ink is commonly favored in manufacturing settings, water-based ink sets are an alternative. They offer certain advantages depending on the manufacturer and intended use.
Above: Mimaki’s water-based inks are designed to suit specific fabric characteristics ensuring exceptional color reproduction on either natural or synthetic fibers for producing fashion textiles, performance sportswear, interior decor, flags, and banners.
Despite UV ink’s multitude of benefits, water-based ink is a strong competitor. This mature ink set is used in traditional printing techniques and also found success with digital printing technologies. In regards to manufacturers, those using digital printing turn to water-based ink for its lower cost and minimal odor, and to satisfy rising safety and health regulations, especially for applications involved with food.
According to Hamid Shirazi, Ph.D, aqueous inkjet ink product manager, Fujifilm Imaging Colorants (FFIC), characterized and safe chemicals—such as surfactants and viscosity modifiers—contributed to the first generation of inkjet water-based inks. However, no inkjet colorants were available, they were borrowed from other industries—food and textile.
“Later a range of novel colorants—dyes and pigment dispersions—were custom developed to overcome some of the shortfalls of the first generation colorants, such as poor water fastness, light fastness, ozone fastness, improved hue, and chroma. Many of these same colorants continue to be used for industrial applications today and more are in development,” continues Shirazi.
Thanks to these advancements, manufacturers adopting digital print consider water-based ink. Demand derives from industrial printing, textile, food, and pharmaceutical industries. “Water-based inks are doing well in traditional paper and paperboard markets. Corrugated, envelope, bags—carry out, and commercial and folding cartons are the providence of water inks,” explains Joe Kelly, VP technical director, INX International Ink Co.
“In textiles, much of the opportunity is driven by increased availability of specialty application fabrics designed for high fashion, performance apparel, and industrial textiles. With an increasing selection of fabrics new and emerging markets are open to this technology,” adds Tommy Martin, product manager, textile and apparel business development and marketing, Mimaki USA, Inc.
Cost makes this ink attractive. “When comparing water-based inks to UV inks, water-based inks are much more cost effective and support higher speeds. However, water-based ink is one of the most expensive liquids per ounce. Given the high demand for printing, there is a need for a low-cost print output,” shares Linda Meyers, press relations, Diversified Nano Solutions Corporation (DNSC).
Dev Sarma, research and development manager, InkJet, Inc., points out that UV inks also require additional equipment, like a curing lamp to cure a substrate, which can get expensive.
“Some UV inks have an unpleasant odor and can be sensitive to the skin whereas with water-based inks, those are not concerns. Also certain industries require water-based ink due to regulations,” adds Sarma.
Water-based inks offer advantages such as eco-friendliness, increasing substrate compatibility, and cost effectiveness.
Eco-friendliness is a major benefit. According to Sarma, water-based inks contain low volatile organic compounds (VOCs), meaning they do not feature the odor common with UV. Another “green” benefit is that the disposal of bottles and other waste is easier. “It is safe, odor free, and eco friendly. While UV inks are safe for the environment, they are more hazardous than water-based inks. Water-based ink contains polymers and tends to be safer than UV ink, which consists of monomers,” he continues.
Material compatibility is also changing for the better. “Technology has evolved so that water-based inks can be used for porous and non-porous materials. Previously, there were no binders, so manufacturers could not print on plastic with water-based ink, now they can,” says Sarma.
Cost is another benefit. “Water-based inks provide the lowest cost in terms of color density over unit area. They can be free of hazardous air pollutants with ultra-low VOCs, making for reduced regulatory involvement. Insurance costs are lower as well,” explains Kelly.
Production-level environments use water-based inks because of their cost effectiveness for larger volume jobs. “Water-based inks are commonly used in industries printing on many items requiring large volumes of ink. They are favorable because they sell for a lower cost than other inks and are compatible with applications that require higher print speeds,” shares Meyers.
Looking into Water
Water-based ink sets are available for industrial printing applications.
DNSC’s V- and E-Series water-based inks are low cost and provide high speed print output. Meyers says that in addition to being eco-friendly, these water-based inks are less hazardous to health. Both the V- and E-Series include CMYK, red, green, blue, and custom Pantone options, proving a water-fast ink set compatible with a variety of porous and non-porous substrates. The E-Series is a pigment-based inkjet ink, whereas the V-Series is a dye and dye/pigment hybrid inkjet ink.
FFIC scientists and engineers are key players in the development of the chemistry and purification science of water-based colorants. The company is active in supplying and manufacturing water-based colorants and fluids for all of the above-mentioned applications. Pro-Jet aqueous inkjet inks are custom designed for inkjet printing applications like laminates, flooring, product marking, packaging, and textiles.
InkJet sells water-based inks for high-speed printing presses for both coated and uncoated substrates. Its direct food contact ink is used to create images on foods specified by the U.S. Food and Drug Administration. This includes consumables such as cakes, cones, soft candies, white and brown eggshells, and vegetables, as well as packaging that may come in contact with food.
INX recently introduced its INXhrc High Renewable Content Water Inks, which offer real advantages of bio-sourced materials and reduced carbon emissions. This is also without the compromise of other print/application attributes, according to Kelly.
Kornit Digital’s NeoPigment direct to garment ink portfolio consists of high-density pigment ink engineered for sustainability. The ink set offers excellent light fastness with a color gamut of CMYK, green, red, and gray. In 2017, Kornit introduced pink and yellow neon ink to extend the portfolio’s color gamut.
Mimaki’s water-based inks are optimized for the Mimaki TX300P-1800 Series direct to textile printers. They are designed to suit specific fabric characteristics ensuring exceptional color reproduction on either natural or synthetic fibers for producing fashion textiles, performance sportswear, interior décor, flags, and banners.
Sensient Imaging Technologies offers SensiJet SX ink, ideal for both porous and non-porous surfaces, to offer adhesion without the use of any VOCs or substances causing concern in regulated applications. The ink manufacturer says solutions can be developed to satisfy the requirements of many applications, adjusting parameters such as adhesion, flexibility, de-lamination, or fastness.
Water-based inks aren’t without challenges. Some of the chemical compositions of the ink sets are limited, particularly in adhesion to a variety of materials.
“On non-absorbent substrates the challenge of water-based inks is to overcome the very high surface tension—water wants to bead rather than wet the low surface energy substrates. While progress has been really remarkable, for water-based inks to ever compete with solvent packaging inks on wide web, very high speed presses, there is much more to be done,” admits Kelly.
Meyers agrees that one of the biggest barriers to increased adoption of water-based inks for manufacturers is material variety. “Water-based inks require mostly porous, paper-based substrates, which limits applications for manufacturers,” she shares.
Besides substrate compatibility, the printing process for water-based ink is demanding. “The biggest challenges for manufacturers using water-based ink is the open time to the printhead—when you want to print after not printing a while, you won’t get the first few pixels. It also has a slower dry time and sometimes a heater is needed to help the ink dry faster. There can also be a limit to what printer is used because certain printheads are restrictive to solvent-based inks,” explains Sarma.
Another hurdle to overcome is meeting requirements of the applications in question. “For food packaging there is another level of safety requirements and mode of exposure that is of importance. Of course food safety is a very complicated matter. However, the food industry and regulatory authorities have well established guidelines for Good Manufacturing Practice and approved list of food compliant colorants and chemicals that have been tested and are appropriate for direct and indirect food applications,” advises Shirazi.
Just Add Water
Water-based ink is an alternative to UV ink sets used in manufacturing environments. It cost effective for large volumes, and gives off little to no VOCs, offering a cleaner, heathier option for applications where strict requirements are in place. The configuration of water-based ink may have a long way to go to reach adhesion levels of UV, but ink chemists are working diligently to achieve this milestone.
Apr2018, Industrial Print Magazine