A decade ago, Americans may not have imagined that injection molded car cups would supersede disposable paper for their trips home from the drive-through. Now thermoformers hope to change the market again, and their weapon to challenge injection molded polyethylene and polystyrene cups and containers is cheap, light, soft, flexible and yet durable — polypropylene.
Polar Plastics Inc. of Mooresville, N.C., has been thermoforming a range of PP beverage cups for a little more than two years, said Claude Jacques, vice president of manufacturing.
"The No. 1 reason is, the technology became available," Jacques said by telephone. "No. 2, there's a major saving. There's a big advantage there."
Analysts, processors and resin and equipment suppliers all say improvements to the polymer, lower cost and equipment innovations are creating new opportunities for companies that thermoform PP cups and food containers.
"Existing markets for PP are being expanded," said Donald Wark, senior principal with Harborside Research Group, a Salem, Mass., research firm.
"A major loser will be injection molded PP, because of the inherent lighter weight of thermoformed PP containers. And we can build a case on the fact that the production economics are better for thermoforming than injection molding."
Wark added that, over the long term, injection molded high density polyethylene also may lose out to thermoformed PP on the basis of price and performance.
Until recently, most North American thermoformers did not own equipment that could handle PP's tough processing parameters,.
But now that equipment is widely available, and PP has made visible gains in dairy and deli containers, single-use beverage cups and disposable and reusable food-storage containers, Wark said.
"Food-storage containers are a very good application for PP because the consumer doesn't require the perfect clarity of glass," said Robert Vanderselt, president and chief executive officer of Anchor Packaging Inc. in St. Louis.
"PP can withstand dishwasher temperatures ... and it's a reasonably low-cost [product] as well, so you can afford to throw it away."
For the past six years, Anchor has been forming containers and dome lids from PP on the 50-inch FM Servo series of equipment from Lyle Industries Inc. of Beaverton, Mich.
OMV USA Inc. in Genoa City, Wis., and International Thermoforming Systems Inc. of Yakima, Wash., are among the few other U.S. makers of the equipment needed to form PP.
ITS and OMV machinery have trim-in-place capabilities that companies have possessed for years in Europe, where the machinery makers say thermoformed PP containers are much more widely used. In contrast, U.S. thermoformers traditionally have used post-form trim presses.
"PP, because of the shrink factor, you can't pass it over to a trim press and trim it," said ITS Vice President James Naughton. "If you did that, you'd end up with a nonconcentric trim."
But trim-in-place capabilities don't always equal successful thermorforming of PP, said Gary Sowden, Lyle marketing director.
"It's not a real simple equation. I'm sure everybody's looked at it," Sowden said. "There are people who say if you're not trimming in place, you're not going to be thermoforming [PP]. I don't believe that at all."
Sowden said Lyle has been producing its PP forming machine with an off-line trim press since the mid-1980s.
ITS, known for the FT-series machines, supplies equipment for deli and dairy containers, single-serve portion cups and yogurt-cup makers like Winpak Portion Packaging Inc. of Bristol, Pa.
John Rose, Winpak's vice president of manufacturing, said his company has thermoformed PP single-serve cups, small salad-dressing containers, 4- and 6-ounce yogurt cups and other one-time use containers since 1998.
Rose said despite the problems associated with thermoforming PP, several factors led his firm to consider the material — and so far it has been a success.
PP is "definitely the material of choice" for hot-fill and freezer-to-microwave packaging, he said. Winpak also likes the potential for PP in multilayer applications, where its oxygen and moisture-barrier properties can extend shelf life.
OMV has developed a shuttle-mold thermoforming machine to deal with PP's high shrinkage rate.
"We get three-and-a-half times more cooling than we do with a conventional thermoformer, so by the time it completes the mold it has just about completed shrinkage," said OMV President Kent Johansson.
His company will debut the E 76, a new in-line extruder/thermoformer, at the June NPE show in Chicago. The machine will be producing 7-inch-deep PP car cups.
"Everybody is saying you cannot make a car cup in PP because it is too soft," Johansson said. "What we do with our system is create a linear orientation like when you do a PET bottle. When you do linear orientation, you get stiffness."
Not only is PP cheaper than polystyrene and PET, its properties are better for high-fat dairy products, according to Frank Nissel, president and CEO of extrusion equipment supplier Welex Inc. of Blue Bell, Pa.
"PS is not very good for high-fatty materials. You can put yogurt and cottage cheese [in PS], but not butter or margarine," Nissel said.
But another reason North American thermoformers had not always used PP is because the machinery for this material typically has fewer cavities and puts out fewer parts per hour than PS forming machinery.
"It's that kind of a problem that's held back all that PP market," Nissel said. "The established American thermoforming people are used to very large machines."
But Johansson said OMV's machinery is coming mighty close to meeting the output needs of U.S. thermoformers. Where PS machines typically run 130,000 cups per hour, he said his machines can run 100,000 cups.
"We have compensated by running the machine very fast," he said. "We're running 30 cycles of PP drinking cups on larger machines.
Johansson does not expect a rapid conversion to thermoformed PP packaging, because of the cost of replacing existing equipment.
"People are saying: `I have my conventional thermoformer, I'll pay a little more for the material,'|" he said.
Rose, however does see polypropylene taking off in the near future — it will just take a commitment on the part of thermoformers, suppliers and customers to make it work.
"We do need to have capacity to make that [conversion to PP] happen, and that's likely to happen over the next two years," he said.