A Coat of Armor

Coating technologies sometimes seem like they can do it all, from the mundane to the smart technology applications that are opening up creative opportunities for package printers and consumer products companies alike. Whether it’s water-based, solvent-based, or UV/EB curing, coatings are helping companies save money and sell product—in anyone’s book, a pretty good combination of benefits.

Each of the coating technologies has an important role to play in package printing. INX International manufactures all three primary types—water, solvent, and energy cured—but Davant Davis, INX national accounts manager, aqueous solutions, throws his hat in the ring for water-based systems offering the best growth potential. His reasons include many practical considerations, such as inexpensive, least energy required, most environmentally friendly, and UV coatable and re-coatable.

Siegwerk Ink Packaging also offers all three primary coating technologies. Kent Shah, technical advisor, acknowledges the benefits that each can provide in packaging applications.

Water-based systems can be applied to meet different application needs, he says, such as gloss enhancement, high heat resistance, slip properties, or scratch resistance. “The water-based varnishes are primarily used for porous substrates with limited application for foil and films,” he notes.

Solvents provide a wide selection of resin choices, providing an opportunity to formulate coatings for paper, film, and foil packaging materials, he continues. “Additionally, these types of coatings can be formulated to provide numerous functionality for packaging applications, such as cold seal release, or water, oil, or other chemical resistance.”

For the energy-curable coatings, Shah says that the UV coatings market has experienced double-digit growth in recent years. However, it has not been adapted in food packaging due to potential odor and compliance issues. “For food packaging, EB coatings are much more suitable and will grow,” he predicts. In addition, EB varnishes are “especially suitable for outdoor applications for a variety of substrates, where it provides protection to ink for weatherability.”

Northwest Coatings LLC is a manufacturer of both water-based and UV/EB coatings, which Vice President and Technical Director, Stephen Lapin, PhD, says are both environmentally friendly technologies. “They offer very low levels of VOCs and do not require the use of thermal oxidizers to manage emissions. Water-based and UV/EB curable coatings are also safer to handle relative to solvent-based coatings.”

UV/EB coating technology has grown steadily in its use in packaging over the past 30 years, says Lapin, and is now in common use in label, multi-wall bag, and folding carton applications. However, he sees the largest growth possibilities for UV/EB coatings in flexible packaging.

“In the past, UV/EB coatings have only been used for a few limited flexible packaging applications. Flexible packaging converters are now discovering UV/EB coatings can offer many advantages, including superior protection of graphics, better heat resistance to allow for improved heat sealing, excellent high gloss appearance, controlled COF [coefficient of friction], and potential cost savings by replacing a laminated structure with a coating on a mono-web.”

UVitec focuses entirely on UV coatings, with the major advantages versus solvent and water being its instant cure and absence of VOCs, says Todd Dickenscheidt, formulations chemist for UVitec. In addition, “UV coatings also have significantly better protective properties than water-based coatings.”

Dickenscheidt also predicts the best growth potential for UV and water-based coatings. “This is due to the reduced VOCs and drying times associated with these coatings over solvent-based. UV coatings will continue to be the high end due to their greater durability, while the lower cost of water-based coatings will make them attractive for applications that do not require stronger product resistance.”

On the horizon

With developments that are well past the drawing-table stage, coating technologies will surely continue to enhance packaging functionality. Their use in surface printing applications is growing for virtually every application, says Shah.

“More and more specialty coatings are being used in providing barrier and government compliance to food,” he observes. “Some of the lamination applications are being replaced with EB coatings. It provides cost reduction as well as just-in-time delivery. Smart coatings are being formulated for anti-counterfeit measures.”

At Northwest Coatings, Lapin reports that one of the most exciting developments it has introduced is water-based and UV/EB-curable insect-resistant coatings. “These coatings have been shown to be highly effective in multi-wall bag and folding carton applications where product losses due to insect infestation can be significant,” he reports. “This technology is also more attractive compared to other measures used to control insect infestation in packaging.”

Both Dickenscheidt and Shah mention the importance of nanotechnology in future coating developments. Dickenscheidt says it will be used to develop smart coatings, while Shah reports that Siegwerk’s R&D “is heavily involved in developing coatings with nanotechnology for barrier applications.”

According to Lapin, although nanotechnolgy “is a popular buzz word, nano-sized materials have been used in coatings for many years. New nano-materials are being developed all the time, but they are just one part of equation when it comes to new coatings for packaging applications.”

Whatever the value-add provided by the use of coatings, the focus, as always, has to be on the customer, says Dickenscheidt. “Each printer must decide what capabilities will best serve their customers, and offer these capabilities to maximize the value of the coatings they will put on their packaging.” n