A Familiar Hurdle

What can’t UV and EB (electron beam) inks do? They cure fast. They allow for high print quality. They’re nice to look at. And, they’re kind to Mother Nature. No wonder they are becoming common in the package-printing industry. According to Don Duncan, director of research, Wikoff Color Corporation, more than 90 percent of all EB inks and at least half of all UV inks are used in packaging.

“As it relates to UV offset inks, the newer ink technologies have a wider operating window, which allows UV offset printers to print using very high screens without having issues relative to water-balance. New UV offset inks are also being used for UV letterpress applications, which allows printers to satisfy both print technology needs while only having the inventory of one ink technology,” says Deanna Whelan, marketing manager, XSYS Print Solutions. “Specialty print techniques such as cold foils and holographic foils are used in conjunction with UV inks and the curing process on press; these effects provide new options for packaging designs and shelf appeal.”

Both UV and EB inks are mostly used in flexographic printing. “EB inks are very well-suited for the flexo printing process and work best in long-run applications where multiple cleanups are not necessary. UV inks can also be advantageous for long runs due to the fact that they require less maintenance than most conventional ink products,” says Ron Zessack, manager of energy-curable products, Environmental Inks and Coatings. “The use of UV/EB inks in flexo printing markets has been increasing at a steady pace and we anticipate this trend to continue with UV/EB becoming a larger part of our business and product mix.”

Not quite there yet. . .

It seems as though everything is “made in the shade” for UV/EB inks. But, one area in which these inks are having difficulty moving is direct food packaging. UV/EB inks are quite common in food packaging, that is non-direct food applications. Currently, the U.S. Food and Drug Administration (FDA) does not acknowledge UV/EB inks as acceptable for direct food contact, although it will consider approval for inks on a case-by-case basis.

“The FDA-compliance issue is two-fold: concern for very small migrations of ink components through the packaging material and into contact with the food/pharmaceutical product and subsequently altering the taste of the product. More importantly, the major concern is these small particulates becoming a health risk,” explains Robert Waddington, general manager, UVitec. He says the inks that are FDA-compliant for direct contact with food are water-based and are “manufactured with relatively benign components.”

Kurt Hudson, general manager of Water Ink Technologies, UV Division, says UV/EB inks are similar to the majority of solvent-based and water-based inks in that all or most of the components in the inks are not generally recognized as safe (GRAS) in FDA Title 21 codes. “UV/EB components are newer and fewer than solvent-based and water-based. Inclusion on a GRAS list may come in time for some UV/EB components, but our government works at a different pace than an industry created by a different set of priorities,” he explains.

According to Duncan, there are three instances in which printed inks are suitable for direct food contact. “One way is for all the components of the ink to be explicitly listed in the FDA section of CFR21 (or other sections of the CFR referenced within CFR21). There are no UV- (or EB-) curable raw materials (monomers, oligomers, or photoinitiators) listed there. So, that approach is out for UV/EB products.”

The second approach is to conduct extraction studies on the printed article to show that no more than 50 parts per billion (ppb) of any item not listed in CFR21 are present, he says. “The 50-ppb level is accepted as the limit for food migration issues being a concern. If any migration potential is less than 50 ppb, then essentially no migration occurs, and thus there is no food contamination, and thus the package (and the inks thereon) are safe for use,” Duncan explains. “This requires testing of a printed product. Depending on how conservative the customer is, it might require testing on a sample from every job. There are some clear EB coatings that are marketed for this approach, but it requires a partnership between the formulator and the coater to make sure the print job is fully cured to the level that was seen in the sample that was used for the original extraction study. This is a complicated approach, and has not seen wide acceptance in the marketplace.”

A third approach is to do the extraction studies and then submit a Food Contact Notification (FCN) to the FDA. “In the FCN, the formulator will basically say, ‘We tested this and it looks good to us. Is it OK to use these raw materials in basically this way without further testing?’” says Duncan, who is also co-chair of RadTech International’s Printing & Packaging Focus Group. “If the FDA says ‘yes,’ then that formulator is good to go. Since the approval information is limited to the submitter, every formulator would have to submit its own FCN.” But, he says methods two and three have significant up-front costs for testing, and the third approach has some FDA fees associated with FCN submission.

In the meantime, The RadTech Food Contact Notification Alliance has recently completed development of an acrylate toxicity profile and found nothing that would compromise safe use in food packaging. “Extraction studies completed under FDA-required protocols confirm that both UV- and EB-curing formulations can be designed, applied, and cured under conditions which assure that extractable monomer, oligomer, and photoinitiator levels will be at or below concentrations that can be considered safe for use in food packaging,” according to an FCN Alliance update on RadTech’s Web site. “Initial feedback from the FDA suggests that preliminary data submitted by the Alliance on acrylate monomer toxicity already may be sufficient to support food packaging safety claims for at least two of the monomers submitted for clearance under the FCN. The Alliance plans to conduct two additional toxicity tests to complete clearances for the remaining monomers under consideration.”

But, for now, water-based inks will continue to be the norm. And, those hoping for the approval of UV/EB inks in direct food packaging will just have to be patient. “The general and specific details of UV/EB formulation make acceptance of direct food contact a high hurdle indeed,” says Hudson. “Without having components generally recognized as safe by the FDA, conformance to zero levels of component tainting is the burden of the printer.”

Worth the debate?

While there are current applications where UV ink could be printed on the inside of a food package and thus, come into direct contact with food, there aren’t that many. In fact, the most common application for UV and EB printing is in food packaging, and the vast majority of UV and EB printing used there puts the ink and coating on the outside of the carton, where it can be seen and appreciated, and away from the food.

The UV and EB inks in the market now are completely suitable for this application, outside a functional barrier. To be fair, there are some applications for some UV products, particularly UV adhesives that could be in direct food contact and a consolidated Food Contact Notification could be a great help there. And, some printers and packaging companies would feel more comfortable with a product that they knew to be acceptable for direct food contact, even though they have no intention of printing UV/EB on the inside of packaging. Also, there are some paperboard fiber recyclers that would be happier with their feedstock using inks known to be suitable for direct food contact.

Personally, I’m not sure how big a market there is for direct food contact UV/EB products. There are, without question, some people who are vitally interested in the success of the RadTech approach. In the grand scheme, however, water-based inks for direct food are well known, readily available, and less expensive. Putting more expensive UV/EB products on the inside of a food package (and presumably on higher cost products where their direct food acceptance is proven) seems like a niche market to me.—Don Duncan, Wikoff Color Corp.