On Print | Low Migration UV-Cure Inkjet Inks

Published: May 22, 2012, By Dene H. Taylor

At drupa, I focused on digital presses for packaging and especially for flexible packaging. HP Indigo and Xeikon, the leaders of toner technology in this area, have new machines with improved width and operating speed, so they are extending the range and increasing applications. You shall hear more about this later.

Recently I said that inkjet just wasn’t in this area because water-based inks have not performed at useful speeds on cost effective films, and UV-cure inks, which do print, have not met food safety standards [see On Print | Inkjet for Packaging]. Landa Corp. showed us a path forward for water-based inks [see Drupa Starts in Style: Landa Intros Web & Sheet Digital Presses] although there is substantial development before reliable commercialization.

At drupa, Agfa told us that it has low migration UV-cure inkjet inks for some food packaging applications. So now there is a second path forward, although it to needs development as there are no presses where the triad of ink/substrate/printer combination has been optimized. So it requires innovators willing to make the investment.

Adoption will not be easy—it has to be application by application because of the regulations governing the permitted accumulation of chemicals in foods. As foods vary greatly in their ability to absorb different chemicals, it becomes necessary to perform extensive combination-by-combination testing to get an approval. Fortunately there is a good portfolio of compounds with established limits from which the sophisticated formulator with the appropriate resources can choose.

There are two routes by which ink compounds can get to the package contents:

• migration through the packaging film
• off-setting from the ink layer to the backside of the film

The first depends on both the chemical and the film—for example polyester is a much better barrier than polyethylene. The second depends partly upon correct formulation as well as on complete cure of all the ink on all the film. This last need is clearly the full responsibility of the printer, so the undertaking is not trivial. But low migration inks for offset are in wide use, and the companies using them will be the most likely adopters, as they already have the controls and proven compliance.

As Agfa explained, almost any food-related application could be printed with UV inkjet, but because of the effort needed to meet the regulations, each must be addressed individually and with significant investment—and followed always with continued vigilance.