By Melissa Donovan
Part 1 of 2
Thermoforming is a process used by manufacturers to create anything from signage to automotive parts. Traditionally, a piece that involved a decorative graphic or color was either hand painted or screenprinted. However, there are digital ink sets optimized for printing to materials that will eventually undergo the thermoforming process.
These ink sets must be able to withstand high temperatures, elongate in some instances up to 200 or 300 percent, and avoid cracking or peeling under pressure. Several ink manufacturers have formulated UV ink sets in particular for this application.
Continuing Interest
A few year ago there seemed to be a big push to use UV ink sets designed specifically for substrates that would undergo the thermoforming process. Based on feedback from this article’s participants, this interest has plateaued instead of accelerated. However, those who initially inquired and subsequently used these products continue to do so.
At Fujifilm North America Corporation, there is not an overwhelming demand for UV thermoforming ink. “But users who invested in the technology through Fujifilm have been successful with their applications,” explains Ramona Serafino, associate product marketing manager, graphic systems division, Fujifilm.
Perhaps interest in UV ink for thermoforming capabilities dissipated because of the focus on directly printing to finished materials and thus eliminating the analog process of thermoforming. “The versatility of UV inks allows for digital printing directly onto materials making the process faster and more cost effective versus time consuming and more costly traditional methods,” comments Deborah Hutcheson, director of marketing, Agfa.
Today’s newest UV LED lamps allow for quick and error-free curing on various substrates and pre-manufactured objects. “The interest in LED curing was driven by the fact that they are a more efficient source of energy with less infrared heat generated. So they run more affordably and cooler than conventional UV lamps. The lower heat produced by LED allows thinner and more heat-sensitive materials to be printed without being effected by the curing process,” shares Terry Amerine, VP – sales and marketing, Polymeric Group.
Many of the UV ink configurations designed for thermoforming compatibility are for printers utilizing conventional UV mercury lamps. However, Amerine adds that the plastic used in thermoforming is designed to be “highly flexible at elevated temperatures” so whichever ink curing process is used, conventional or LED, the substrate is less susceptible to damage.
Michael Maxwell, senior manager, corporate strategic development, Mimaki USA, Inc., notes that thermoforming through a digital print process does benefit from LED curing technology. “The heat and intensity of traditional UV bulbs can scar or deform plastics to be thermoformed.”
Addressing Demand
For those using the product, there is a consistent demand for thermoforming ink in the digital space. The benefits of using digital printing versus screenprinting for this application continue to outweigh any challenges it presents.
“Digital printing/thermoforming offers a shorter setup time compared to screenprinting, provides higher quality with the potential for near-photographic images, and allows prototype work to be fast and economical,” says Serafino.
Common users of digital ink designed for thermoforming include high-production packaging manufacturers, point of purchase businesses, and sign shops, shares Kitt Jones, co-creation product manager, Roland DGA Corporation.
Maxwell says he’s experienced increased demand for thermoforming on a smaller scale, with applications such as Halloween masks and decorative pieces.
“Thermoforming with digital print technology is used by manufacturers handling a range of product substrates, including vinyl, ABS, acrylic, polyester, polycarbonate, and polypropylene. UV LED ink sets designed specifically for thermoforming are the mainstay of this segment,” says Phil Jackman, global product manager, digital, Sun Chemical.
Besides UV and even UV LED ink, other ink sets are also considered for use in the thermoforming process. Amerine sees an emergence of latex ink use as it offers key advantages in terms of flexibility and color gamut.
“UV ink is still the best choice for stretch and diversity, but we also see a need for other types of ink applications,” agrees Jones.
Recent Advancements
Important characteristics when considering a UV ink set that works well in the thermoforming process include the ink’s adhesion, elongation, and durability. As with any product, manufacturers continue to make advancements.
According to Jackman, there are five aspects to look for when considering UV ink sets used in thermoforming applications. A good backing white is important for clear substrates, especially if backlit. Highly lightfast pigments are recommended since many thermoforming applications are used outdoors in extreme conditions. Good adhesion is a must to perform well on challenging materials.
“Fourth is surface resistance, as the inks need to be stackable following printing. Inks must have the resistance to the heat in the forming process and be stackable after forming during the transportation process. The fifth aspect is long-term flexibility, which is needed to ensure the prints’ performance over time, especially in cases where the temperature is known to fluctuate,” continues Jackman.
Beyond ink, other advancements associated with the thermoforming process are in development. “We have actually been working more on functional coatings designed to go over the ink. The coatings provide enhanced performance in terms of durability, chemical resistance, and antimicrobial properties,” says Amerine.
Strutting Their Stuff
Digital ink developed to undergo the thermoforming process is still used. While interest may have peaked a few years back, it stands to reason that anyone continuing to leverage digital printing in lieu of analog technologies benefit.
The next article in this two-part series looks at available ink sets for thermoforming. IPM
Oct2020, Industrial Print Magazine