Technology Focus: Aqueous, Latex, and Resin Printers
At one time, the only consideration when looking at digital printing with water-based inks was whether it was dye- or pigment-based. And those two choices just meant the print would fade in days or months, certainly not years. Fast forward to today and the choices when looking at water-based ink are much broader and diverse. When deciding what printer or ink technology, remember it’s all about application, application, application.
When it comes to proofing or engineering drawings, most of the choices are pigment-based, though there are still dye-based inks being used for some applications. Proofing printers in many cases will add gamut expanding inks such as orange, green, or violet to cover as much of the Pantone library as possible for color-accurate proofs. Epson proofing printers certainly make up a large share of the market, and some of its proofing printers can hit 99% of the Pantone library. You can also find solid water-based printers from Canon and HP. Outdoor durability is very limited (months in certain environments with lamination), but that isn’t what these printers are designed to do.
A Look at Latex
The largest offering in aqueous inks for outdoor applications is latex, and HP is a big presence with its latex printers. I talked with Thomas Giglio, North American Latex Business Lead, HP Graphics Solutions Business to find out more about its latex product line. While the standard in large-format printing has been a progression from solvent, to mild solvent, to eco-solvent and UV-curable, the HP Latex is a water-based ink with the same or better durability.
Water makes up 66% of the composition of these inks, so there are no hazardous air pollutants (HAPs), which results in odorless prints. Also, because heat is used to evaporate the water from the ink during printing, and then cures the resin co-polymer (latex), the prints are ready for laminating and/or finishing immediately, as opposed to waiting for the other ink technologies to outgas — a process that can take a minimum of six to 24 hours (depending on the amount of ink on the substrate).
Two applications that are a great fit for latex is interior décor and vehicle graphics. For interior décor, most customers want eco-friendly graphics without odors that have some sustainability characteristics (such as UL Greenguard Gold or Leed certification). HP latex prints on a variety of wall graphics materials and soft signage durable textiles with a thin layer of ink that allows the characteristics of the substrate to be preserved through the ink.
For vehicle graphics, latex ink offers excellent density and elongation for surfaces such as compound curves. Wrap companies prefer latex because there is no outgassing to delay production, and the stretchability of the inks. If you have an install crew in the field (or the shop for that matter) and a panel is damaged, it is easy to re-print another and substitute it in, as you can laminate immediately and use it right away. HP latex inks are part of the 3M MCS and Avery ICS warranty programs.
Giglio shared that the HP latex graphics are durable up to three years unlaminated, and with the appropriate lamination, the warranties from 3M and Avery are up to seven years. The printhead technology is thermal and user-replaceable — printheads are less than $200 each. The printhead is 1,200x1,200 dpi with a 10-11 picoliter droplet. Typically, a printhead will jet approximately six to seven liters of ink before replacement, but that depends on the environment and frequency of printing.
The printer also uses an optical media advance sensor (OMAS), which is essentially a camera located within the printing platen that takes pictures of the back of the media (reading the fibers of the backing paper) as it passes over the platen, and then adjusts the feed motors to adjust carriage deployment for over- or under-advancement of the media. The result is band-free printing.
And of course, if you are looking for a flatbed printer, HP has a latex printer that will fit that bill as well. This allows a PSP to grow its print offering without introducing a different ink technology into the mix, which can be a challenge when color matching. HP introduced its latex flatbed printer in 2018. A couple unique features are ink curing at a lower temperature and the introduction of the Latex Overcoat as its own channel, which can be turned off to offer maximum adhesion with lamination or post-coating. Another unique aspect of the latex flatbed is white ink that can be taken out when not in use — instantly — and replaced when needed for an “on-demand solution.”
Michael Maxwell, senior manager – Corporate Strategic Development with Mimaki USA, shared that the JV 400-160 LX is a 64" latex printer first developed in 2007. The JV 400 is the only latex printer offering orange and green expanded gamut inks, and was the first to introduce white, orange, and green inks into the latex market. The JV 400 is useful for posters, art, POP, advertising, and giclee. This is a cartridge-based printer and with the exception of white, which is a 220 ml cartridge, the other inks are available in 600 ml cartridges. The JV 400 uses two in-line piezo printheads with print resolutions of 600, 900, and 1,200 dpi.
A New Contender
A new player in the durable water-based outdoor ink arena is Epson, with its new resin ink printer. I talked with Matt McCausland, senior product manager, Epson America. The new resin is good for outdoor signage, indoor graphics, wall coverings, and vehicle wrap graphics. Ink adhesion for the resin-based printer occurs at a lower temperature, which allows for more substrates to run through the printer. The durability of the ink is comparable to solvent printers, as the pigment is very similar to what is in solvent printers. The Epson resin printer uses a pre-heater, platen heater (this heater pins the ink and starts the cure process), and then a post-cure heater.
The Epson resin printer uses the new Precision Core Micro TFP (thin film piezo) printhead. This printhead is 2.6", and can jet a 4.2 picoliter droplet for high quality prints. The printhead is 300 dpi tall for print resolutions of 600/1,200/2,400 dpi. This new printhead is meant to last for years, and is user-replaceable — a feature not found on most piezo printheads — and is relatively inexpensive at $695 when registered for the Epson Cloud Solution PORT software (especially considering that piezo printheads are not something the average user would ever replace without calling a technician.) Another new feature is the ability for this printhead to do an inkless nozzle check. The printhead checks the nozzles by sending a pulse to the piezo and then measuring the result of the pulse. If there is a blockage, the nozzle would get a different reading than a clear nozzle, and a cleaning would be recommended. The Epson resin printer comes with cyan, magenta, yellow, black, light cyan, light magenta, and an optimizer. Resin inks come in 1.5-liter ink bags. Lastly, the Epson is designed with a robust and precise feed system for print length consistency.
Knowing your specific application will help to guide you when selecting a printer. If your application would be well-served by one of the printers in the aqueous, durable aqueous, latex, and resin printer categories, then check out one of these offerings.
Ray Weiss, Director of Digital Print Programs for PRINTING United Alliance, joined the Association in 2014. He assists association members with technical information on digital printing as well as digital equipment, materials, and vendor referrals. He oversees training and certification workshops at PRINTING United Alliance along with the Association’s Digital Equipment Evaluation program. Ray is project manager for both the PDAA Certification program and PRINTING United Alliance's Digital Color Professional Certification program and is an instructor for the Color Management Boot Camps. Ray regularly contributes to the Association's Journal and won the 2016 Swormstedt Award for Best in Class writing in the Digital Printing category. Outside of work, Ray enjoys biking, international cuisine and spending time with his three fantastic grandkids.