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Conagra pops up a winner

When brand managers and packaging engineers at Conagra saw an opportunity to delight the consumer and differentiate their microwave popcorn brand, they didn’t hesitate.

The package's tear-away film lid and outer folding carton.
The package's tear-away film lid and outer folding carton.

What do you get when you combine a special dry-bond adhesive, in-line laser scoring, clever problem-solving in the transport of large rolls of laminated material, and custom modification of a horizontal form/fill/seal machine so that it produces a unique venting feature in the finished package? At Omaha-based ConAgra Foods, you get an Orville Redenbacher’s Pop Up Bowl that is a significant improvement over the traditional paper microwave popcorn package. No wonder the package won the Highest Achievement Award in the 2012 FPA Awards competition.


The goal behind this packaging development was to come up with a package that would turn into a wide-mouth bowl as popping occurred. This eliminates the need to pour popcorn into a separate bowl. It also provides new usage occasions because consumers can now take the package on the go without worrying about what to do with their bowl when the popcorn is gone.


The Redenbacher brand has been a leader in the microwave popcorn category for years. For most of that time, ConAgra’s in-house converting operation in its Maple Grove, MN, facility has been the source of the microwave popcorn bag material. But to produce this new material—a unique combination of paper, polyester, susceptor patch, tear tape, and new adhesives all combined in an extraordinarily creative design—in the same plant on existing laminating equipment took some doing.


First, all adhesives had to be water-based because the plant didn’t have—and had no interest in applying for—the regulatory approval to handle the volatile organic compounds inherent in solvent-based adhesives. A dry-bond adhesive system from Henkel (www.henkelna.com) was crucial in overcoming the unique lamination challenges involved in getting the microwave susceptor patch into the complex lamination.


Second, the bag’s opening feature—a tear-away polyester film lid—is what allows the package to transform into a stable wide-mouth bowl after opening. To provide consistent removal of the film lid by the consumer, ConAgra used in-line laser scoring of the 90-ga polyester film. This reduces its tensile strength in precisely the desired locations and facilitates opening. In addition, a polyester-based pressure-sensitive tear tape was laid over the top of the laser score to provide consistent tracking of the tear, prevent zippering of the tear, and eliminate loose film edges after opening.


Third, consistent and safe venting of steam during microwave cooking was critical to the functionality of the package and to consumer safety. A unique and patent-pending system was created that involves punching a vent feature in the laminated structure during the package-forming process on the PSA horizontal form/fill/seal system. Adhesive around the venting feature is then sealed to prevent leaking of oil during transport until the package is used in the microwave oven. During cooking, pressure builds up and the adhesive seal releases to vent steam safely.


Two-up production
According to ConAgra’s David France, senior principal packaging engineer in Packaging Research, Quality, and Innovation, the converting process is a two-up process. “We make the rollstock for two packages of material side by side and then slit it at the end for rewind,” says France.


The laminating process begins with 90-ga polyester going through a two-side corona treatment that allows good bonds to develop between the polyester and the inks and adhesives that need to be applied. Next is in-line laser scoring of the polyester on a Preco system to achieve the easy-opening feature described above. A flexo print station follows, where the dry-bond adhesive is applied in register for subsequent placement of the four susceptor patches—two for each package. Infrared drying dries the adhesive until it’s just tacky enough for the susceptor patches to bond firmly. Vacumet provides the metallized susceptor patch material in the form of continuous strips, and the ConAgra system cuts individual patches from these strips.


Now the four polyester-based, pressure-sensitive tear tapes mentioned above are applied. These come from Payne. “They help give the consumer a nice, even removal of that polyester lid,” says France. “The polyester has a tendency to want to zipper, and its central tear resistance is not really great, so it doesn’t quite follow the laser score lines as evenly as we’d like if we don’t apply these tear tapes.”

LAST CHANCE TO SAVE! New Trends for Food at PACK EXPO Southeast
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LAST CHANCE TO SAVE! New Trends for Food at PACK EXPO Southeast