In the labels and packaging space, low-migration inks offer several key benefits, and their usage continues to grow. This was a theme during TLMI’s inaugural printTHINK Summit, held in Chicago, IL, USA, from September 6-7.

The session involved presentations and a panel discussion from Tom Dupont, corporate R&D director at acpo; Tom Hammer, product manager at Flint Group; and Catherine Nielsen, partner at Keller & Heckman.

According to acpo’s Dupont, the flexible packaging market is expected to grow from $97.97 billion in 2016 to $125.66 billion by 2021, at an estimated CAGR of 5.11%. Flexible packages are often being used for food products, since, as Dupont notes, “labels have become the bag.” Low-migration inks are frequently used on flexible packaging, especially for foods.

A flexible package consists of a sealing web, which is on the inside of the package, and a laminating adhesive. Additionally, there is a print web and a barrier, as well as the ink that is used to spread the brand’s message.

“There are things that we can do as narrow web suppliers in this flexible packaging world that we can get started on immediately,” said Dupont. “Then we can grow and get into more specifications. With laminating adhesives, the adhesive has got to stick to something and that’s lost sometimes in the whole narrative about how we put two substances together.”

Nielsen presented the regulations and application requirements, a crucial aspect of low-migration inks. According to Nielsen, the system in place in North America has not undergone much change since 1958, and only slight modifications have occurred over the last decade. This stands in stark contrast to constant changes in the European Union.

The US Food and Drug Administration (FDA) must clear all printing ink components that could be defined as “food additives.” Section 201(s) of the Federal Food, Drug, and Cosmetic Act addresses indirect vs. direct contact. The inks must also meet the purity standard of 21 CFR 174.5 of the FDA’s Good Manufacturing Practices (GMP) regulation.

“Compliance is with all of us,” said Hammer. “We have to work together to provide proper components to the brand owner. The goal, obviously, is to protect human health, and the brand owner and their business.”

The FDA maintains a host of regulations for components of a label, including coatings, substrates and colorants for polymers.

As far as regulations for adhesives, Section 175.125 of 21 CFR 174.5 covers pressure sensitive adhesives for labels or tapes applied directly to food. This typically deals with meats and vegetables, and it states that adhesives must be separated from food by a functional barrier, or used so that the quantity of adhesive contacting food does not exceed limits of GMP.

Migration often depends on the concentration of an ink component, volatility, type and thickness of materials separating food from ink, the duration and temperature of exposure, and the type of food.

“Volatiles can transfer through the bag,” said Dupont. “We talk about the inks migrating in, well the volatiles can migrate out and start affecting the adhesive. You want the adhesive to overcompensate and withstand–not plasticize.”

According to Nielsen, “low migration does not equal no migration.” A migration determination can be based on 100% migration calculations, diffusion calculations that model testing conditions, extraction or migration testing, or self-determination. In the US, if an ink or adhesive component “may reasonably be expected to migrate to food,” options include a regulatory clearance under 21 CFR parts 170-179, a GRAS (generally recognized as safe) position based on listings, toxicity data or low exposure, a prior sanction, or the individual must file a TOR or Food Contact Notification to get clearance.

Hammer added that potential migrants include plasticizers from plastics or inks, solvents, washes and cleaning chemicals, oils and greases, and low molecular weight components from substrates and inks.

“Low migration inks are formulated that, if correctly applied and cured and with the right choice of packaging concept, the legal migration levels can be met,” explained Hammer.

There are no differences in the requirements regarding, UV cured, water-based, or solvent-based inks, as well as coatings or adhesives of any kind. Printing processes and the type of machine, printing speeds, the type of curing, and the packaging and labeling materials can ultimately have an effect on migration. Typically, Tenax (for dry foods) and 95% ethanol are often used to simulate migration tests.

There are challenges with these tests, though. “Migration is linked to high molecular weight of ingredients and the fact that UV ink is hard to get fully cured,” said Hammer. “Most UV formulations have an excess of photoinitiators to guarantee cure. Not all chemistry, such as photoinitiators and monomers, will fully react/polymerize.”

To date, the cost of low-migration inks has been significantly higher than the conventional options. Printers can also sometimes be resistant to change, as they don’t fully understand the risks associated with migration. The newer technology also often requires dedicated presses to low migration jobs and changeovers, as significant cleaning, time and money is necessary.

“The narrow web market is getting into more flexible packaging and food applications, so we’re going to be hearing more about low-migration,” said Hammer. This issue is not going away.”

“When the package is all said and done, the government is going to come,” Dupont added. “You either need to test it or analyze it to make sure that all the components work, and we don’t get in trouble.”