Furthering Substrate Functionality

Like to fool around with the functionality of your films? Want to print that hard-to-adhere-to substrate with water-based inks to reduce VOCs? If you answered “yes” to either of these, then plasma treating may be a technology to investigate for your operation.

Metallizers have taken advantage of plasma treating's ability to “functionalize” substrates for some time, says Valmet General VP Tony Broomfield, Valmet Converting, Charlotte, NC (valmetconverting.com). “Only really since the late 1990s was the technology developed sufficiently that [it] could have an affect on the high-line-speed machines, like the aluminum metallizing machines used in packaging applications.”

In metallizing applications, the plasma treatment process takes place in a vacuum chamber, hence the description “vacuum plasma treatment.” It's used to improve the adhesion of the metal, usually aluminum, says Broomfield, to the polymer film. “It's also used to improve barrier. The barrier property improvement, in most cases, comes from the adhesion improvement,” he adds.

But some companies are taking the vacuum out of the process and putting plasma treatment into the “regular” atmosphere so the technology's benefits can “functionalize” substrates used in web converting applications.

“Atmospheric plasma treatment optimizes ink and coating adhesion, even lamination adhesion, by delivering gas chemistry to the surface of materials, therefore ‘functionalizing’ the surface of webs,” explains Rory Wolf, director of business development for Enercon Industries, Menomonee Falls, WI (enerconind.com).

But if you're wondering why you shouldn't just stick to the tried-and-true corona technology to treat your webs, then try to print on Teflon (DuPont's product known for its non-stick property) with an environmentally friendly water-based ink. I haven't tried it, but my sources indicate it probably won't work, or at least not very well.

But, reports Dr. Angelo Yializis, president of Sigma Technologies Intl., Tucson, AZ (sigma-technologies.com), with atmospheric plasma treatment, it will. “[It] allowed us to improve the functionality, or the adhesion of surface, so much that we actually put 60 dynes on Teflon and printed it with a water-based ink. And we got adhesion.”

Wolf does concede the investment in atmospheric plasma treating equipment is higher than for corona treatment systems, but says, in addition to its usefulness for difficult-to-treat materials, it provides “considerable” return on investment. “Most companies find the return is within a year, so that's what makes it attractive.”

With such swift ROI, and its additional environmental benefits, will plasma treating eventually replace corona? Suppliers seem to think “not necessarily.”

“It's my belief that no one technology really replaces another,” says Dr. Yializis. “These days, CDs are used considerably more than [cassette] tapes, but tapes are still there; they still serve a purpose. And corona is cheap, so there will always be some applications [that use it].”

So if you find yourself fooling around with your substrates, seeking more adhesion, plasma treatment may be worth a look.

According to the experts, there are few, if any, substrates the technology can't tackle, and in addition to creating superlative adhesion today, it's poised to create even more value in the future. At that point, I may be asking: “Want to improve barrier without lamination or coextrusion?” Or maybe, “Want to create a package that senses chemical contamination?”

Restrictions of time and space limit the number of companies, products, and trends that we can discuss in these reports. For additional information, see PFFC's features and departments each month, consult the June Buyers Guide, and check pffc-online.com

Enercon Corona Technology

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