By Melissa Donovan
Digital UV inks offer elongation features designed to withstand the intense thermoforming process, while simultaneously maintaining durability and flexibility. Traditional practices of decorating vacuum-, pressure-, or drape-formed products—three common types of thermoforming—involve hand painting or screenprinting prior to thermoforming, or manually adhering printed vinyl after a piece is thermoformed. Digitally printed thermoforming applications offers advantages such as shorter runs, efficient prototypes, and increased customization.
Above: Featuring 1,000 percent elongation, Fujifilm Uvijet KV inks offer adhesion to a range of materials and excellent finishing properties such as bending, creasing, routing, and guillotining.
Direct to Digital
Manufacturers that provide thermoforming capabilities should be aware of the benefits UV digital printing offers. Primarily, the time saved in printing to the material prior to thermoforming is one of the most influential reasons to consider adding a UV digital printer or outsourcing to a print shop with the capability and know how.
“Digital UV promotes a much faster prototyping turnaround and offers the ability to provide shorter run lengths without sacrificing margin,” shares Josh Hope, senior manager, Mimaki USA, Inc.
In this space, according to Richard Hulme, global sales and product manager, Sun Chemical Corporation, digital print offers advantages commonly found in other sectors effected by digital, including personalization; one-off prints; and reduced lead time, waste, and stock holdings.
When not digitally decorated, a third-dimensional (3D) formed sign for example, may be hand decorated. This process could take days or weeks, says Mike Plier, ink business development director, EFI. “With digital direct-to-substrate printing that process can be done in hours, including the time and trials it takes to ensure a design is correctly aligned with a mold. Making test prints to try on a mold is also costly and time consuming with screenprinting, but again, it is something that can be done in minutes with a run of one piece on digital,” he continues.
Markets that Matter
Digital print’s relationship with thermoforming benefits traditional applications in this segment like signage and automotive parts, but it also transports these pieces into new arenas. Any market looking for a cost-effective way to manufacture 3D prototypes is a fit.
Heather Rockow, energy curable business development, Kao Collins Inc., lists several verticals poised to benefit from digitally decorated thermoformed products—sign makers, in-mold decoration part makers, toy manufacturers, helmet manufacturers, electronics manufacturers, and appliance manufacturers.
“No matter the market or customer, the benefit from digital’s relationship with thermoforming is effectively the ability to deliver prototypes quickly and easily and getting the process closer to the consumers,” admits Hulme.
Plier says EFI’s customers have created a number of items using digitally printed pieces that are then thermoformed. These include ATV fenders, custom marine and automotive parts, hunting blinds, car top carriers, and shower and bath enclosures.
“It is very good for any market that needs small lot/variable data printing with 3D signage since there is no need to prepare plates or screens. In addition, all of the printing artwork information can be stored via computer, saving space in their workplace as well,” adds Kenji Suzuki, director of research and development inkjet technology, INX International Ink Co.
The signage market is of particular interest to many vendors in the space. “The chance to make unique signs in full color gives an additional benefit to existing market applications,” says Pedro J. Martinez, CEO, Afford Industrial.
Jay Roberts, product manager, UV printers, Roland DGA Corporation, argues that most of the demand comes from sign and packaging manufacturers, but he’s also experienced interest from advertising agencies. These companies regularly explore new avenues for point of purchase displays and enjoy experimenting with unique and different print methods to diversify from the competition.
Performing Under Pressure
Digital UV ink used for thermoforming should feature elasticity, adhesion, and durability. The vacuum-, pressure-, and drape-forming process involves intense heat, pressure, and stretching. And after that, finishing tools are often used. The ink must be able to withstand all of these challenges and yield a high-quality print. In addition to physical characteristics, specialty options such as white or clear inks are also attractive for aesthetic reasons.
According Plier, UV thermoform-able ink systems, once cured, create a free film enabling the ink system to become malleable when thermoformed. These free-film properties are also the reason why inks withstand the forming process without cracking or loss of color densities for both first and second surface applications.
“The ability to create signs with heavy curves, bends, and bulges without cracking the ink is a huge advantage. With ordinary inks, cracking or elongating under the stretch can greatly distort and interrupt the graphic—negative effects that are very noticeable in signage text, especially when signs are backlit,” adds Roberts.
Whether used indoors or outdoors, an ink’s elongation properties should be 1,000 percent, recommends Kaz Kudo, associate marketing manager, Fujifilm North America Corporation, Graphic Systems Division. “This allows UV inks to stretch without cracking during the forming process of the printed piece while still providing strong and vibrant colors.”
If the ink does not feature a wide color gamut, cautions Plier, it will change during the heating, pressure, or stretching that occurs during the thermoforming process.
Post process should also be considered. “The ink has to successfully bond with the substrate and offer a good performance to shearing, milling, cutting, and bonding to top coatings as well,” suggests Villanueva.
Hulme believes in addition to adhesion, surface resistance, and long-term flexibility, a good backing white and highly lightfast pigments are necessary. “White is important in the case of clear signs, but it also needs to transmit a nice clean white when backlit. The highly lightfast pigments are important as thermoforming applications are often used outdoors in challenging conditions.”
“It may make sense to look for a digital UV ink that offers white and clear inks for the widest range of application and substrate options,” agrees Hope. Other aesthetically important considerations involve “fabricators checking the specific ink’s properties to ensure intricate textures of decorative fine prints can be retained even after molding and that raised areas of thickly applied ink and double/triple layer printing also stay intact without cracking.”
Open to Options
Several ink manufacturers craft specific chemistries of their products for thermoforming applications. Many ink sets are developed for use in a particular digital printer.
Afford suggests its 838 Series of UV -curable pigmented inks for use in thermoforming applications. The inks print on most plastics, vinyl, treated metals, and treated glass, all while offering good adhesion, scratch resistance, chemical resistance, flexibility, and elasticity. Elongation of up to 600 percent can be achieved.
EFI’s SuperDraw UV inks offer elongation, adhesion, and consistent post-draw opacity for thermoforming applications on PETG, acrylic, polycarbonate, polystyrene, and PVC. The ink is resistant to both heat forming and finishing, which results in no chipping or cracking. EFI SuperDraw UV is available in CMYK and white. It is recommended for use with the 64-inch EFI H1625-SD hybrid printer.
Fujifilm provides Uvijet KV inks, which are specifically designed for decorative print used in thermoforming. Featuring 1,000 percent elongation, the ink set offers adhesion to a range of materials and excellent finishing properties such as bending, creasing, routing, and guillotining. Uvijet KV is available in CMYK and white, with an anti-reflective low-satin finish. The ink is developed for Fujifilm Acuity Select and Acuity Select HS platforms.
Kao Collins’ inks used for thermoforming fall under its Ultra portfolio of UV-curable inks. They address both the graphic arts and industrial printing market.
Mimaki announced LUS-350 UV LED ink in 2016. The durable and flexible ink is specially created for the thermoforming market. When cured it is resistant to scratching and when heated it can stretch up to 350 percent. After molding it does not crack, making it ideal for printing to PETG, acrylic, polycarbonate, polystyrene, and PVC. The ink is available in CMYK and white for use on the Mimaki JFX200-2513 and UJF-7151 plus UV LED flatbed printers. A clear option is also available for the UJF-7151 plus.
In early 2012, Roland launched its ECO-UV S inks for packaging, in particular it found great success in printing on shrink wrap material. Thermoform producers noticed this and began using the product in their own processes. ECO-UV S stretches up to 220 percent with no peeling or cracking. This particular formulation is available in CMYK and white on the Roland VersaUV LEJ-640 hybrid UV LED flatbed printer and the VersaUV LEC series of UV printer/cutters.
Sun Chemical offers high adhesion with its Crystal UVG, which delivers elongation properties up to 250 percent. This can be increased even further depending on the application, with the chemistry capable of achieving elongation up to 500 percent. It provides ideal adhesion to vinyl, ABS, acrylic, polyester, polycarbonate, and polypropylene. Crystal UVG is designed for a variety of digital presses from a number of original equipment manufacturers.
Digital and Thermoforming
UV ink sets designed for use in printing to materials that will eventually undergo the thermoforming process are flexible, yet durable. With this winning combination, fabricators in many industries benefit from the advantages digital printing technologies present, including shorter turnaround times, less waste, decreased error, and increased options for unique one offs.
Mar2018, Industrial Print Magazine