Technical prowess, flexible style

Two improved package materials, one for cup lidding, one for microwave wrapping, secured Technical Innovation awards in the Flexible Packaging Assn. competition. Printing and Environmental Achievement awards also went to new technologies.

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Pushing the envelope by making improvements on existing materials was the way two converters and their customers won Technical Achievement awards in the 2000 Flexible Packaging Assn. (Linthicum, MD) packaging competition. In fact, one improved material, a second-generation Wave Wrap™ from Phoenix Packaging (Maple Grove, MN), is so unique that its first customer is a food processor in Northern Ireland.

The other Technical award went to RJR Packaging (Winston-Salem, NC) (1) for its development of a new foil lidding material that improves seals when die-cut and sealed onto plastic cups of juices and drinks. Although its customers are not overseas, RJR’s material is first sent to another converter that prints and die-cuts the material into individual magazine-fed pieces.

Called Universal Coex Lidding, RJR begins with 1.5 mils of aluminum foil covered by a water-based acrylic top coating. This is laminated to a coextruded coating of 4# of ethylene acrylic acid and RJR’s proprietary sealant blend. This lamination typically replaces 1.5 mils of foil with a 3# solvent-based heat-seal coating.

In the case of the winning material, RJR supplies rollstock to Kraft Seal Corp. (Lake Forest, IL). There, it’s printed by flexo in three or four colors and die-cut into lids with pull tabs. Kraft Seal now supplies the lidding to Cal-Tex Citrus Juice, Houston, TX, for its Vita-Fresh juices, and to Gregory Packaging, Newark, NJ, packer of the SunCup brand, both for lidding of plastic cups of juice.

Secondary converters like Kraft Seal had been seeking lidstock that would offer more consistent seal integrity and resistance to abuse from temperatures and transportation. Some of these packages, says Matt Koschak of RJR, undergo a freezing step that allows the plastic cups to expand and form ice crystals that can puncture both the lidding and even good seals to create leakers.

Total conversion

“We’ve converted 100 percent to this new lidding material,” says Ron Peterson, vice president and general manager at Cal-Tex. “In our experience, it has eliminated leakers. While you can’t ever say 100 percent, we’ve had no complaints since we began to use the new lidding.”

Cal-Tex packs a variety of juices into 4-, 6-, and 8-oz cups and markets nationally to all 50 states, including Hawaii. So it was important that the integrity of the seal be maintained under a wide variety of environmental conditions. “Our packs were vulnerable to different issues, a long truck ride, high altitude or abusive handling at different locations,” Peterson reports. This material was tested under all sorts of conditions, he adds.

Also important to Cal-Tex was that it not require closer tolerances on sealing equipment. “If the temperature ranges or dwell time ranges had been too tight, we wouldn’t have made the change,” says Peterson. “We definitely wanted a material that would be more tolerant, because our machines don’t always maintain the temperatures and dwell times that are set.”

That was also true for Kraft Seal. “The beauty of this is that it does process the same in printing and die-cutting as the previous materials,” says company president, Joe Kraft. “We’re not put at a disadvantage; so that turns out to be an advantage to us.”

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