By Jan H. Schut
For decades an incredible amount of inventiveness has been thrown at the challenge of trying to thermoform bottles. The idea was that making bottles out of thin sheet would save 20% to 50% in materials over extrusion blow molding with lower energy, higher output, and easy material and color changes—including barrier—just by changing a roll. Over the years probably a half dozen ingenious technologies were patented, built, announced, and some even exhibited at major trade shows, without ultimately making a commercial bottle.
The string of patents on thermoformed bottles makes fascinating reading. Some are from well-known names in packaging like Hartmut Klocke of the Klocke Group, who applied for a patent on “Thermoforming Packaging” of bottle-like containers in 1981 (German Pat. DE 8135111U1). Others are from relatively unknown inventors like Rudolf Holzleitner, principal of Hol-Pack Verpackungen, Piberbach, Austria (www.hol-pack.at), a processor of PC bottles.
Holzleitner’s patented technology (European Pat. # EP 2091829) resembles twin-sheet thermoforming, but for disposable bottles up to 1.25 liters. One side of the bottle is deep drawn, including the bottle spout. The other side could be flat or half round. Building bottles with unmatched halves opens wonderful design possibilities. The seam between halves could be vertical or horizontal, making two-colored bottles possible horizontally or vertically and even multi-chambered bottles or packs of detachable bottles. Holzleitner got some support from the Austria Wirtschaftsservice Technology and Innovation in Vienna, but not enough to launch the technology, so eventually he let it lapse.
Patents for thermoforming large bottles like Holzleitner’s are unusual. The target for most thermoformed bottle technology has been for single portion yogurt and juice drinks as an extension of form-fill-seal machinery. Erca Formseal S.A. in Cortaboeuf, France (www.oystar-group.com), part of Oystar Group in Germany, announced “Open Mold” thermoforming of bottles in 2003, showing it for the first time at the Emballage show in Paris (www.all4pack.fr) in 2010. The patented process (U.S. Pat. # 7585453) reportedly can make 6000-18,000 standard yogurt cups/hour or 9000-16,800 thermoformed bottles/hour with walls 0.7 mm thick for material savings of 20%. The patent describes “a plastic stretching device to reduce the plastic bottom web thickness in the unused thermoforming areas.” But the technology wasn’t in fact material efficient, Erca says, and isn’t being offered now, though research is still going on.
In 2008, a builder of thermoforming and form-fill-seal machines, Illig Maschinenbau GmbH in Heilbronn, Germany (www.illig.de), got into the market with Bottleform technology, which Illig demonstrated for the first time at Interpack in Dusseldorf, Germany (www.interpack.com) in 2011. A Bottleform BF 70 machine reportedly can make up to 25,000 x 200-ml bottles or cups/hour depending on shape and size, using sheet from 0.4 to 2 mm thick. Bottles can have steep undercuts for necks or even pedestal shapes. The technology can mold partially threaded necks, but the necks couldn’t withstand the torque of screw caps, Illig says, so bottles would be foil sealed and shrink-sleeve labeled. Illig’s process is now also called “Open Mold Forming” because it can thermoform standard cups as well as bottles.
Illig’s technology is a proprietary combination of vacuum forming, pressured sterile air, and plug assist with tooling undercuts to form necks. The BF 70 machine can have up to 20 cavities and use 68% of 26-inch-wide sheet for bottles or for cups. Depth of draw can be up to 5.7 inches with 2:1 draw ratio for bottles from 50 to 200 ml. The machines could be all stainless steel for use with clean, ultra clean or aseptic fillers for Federal Drug Administration approval on food filling lines. Illig’s “Open Mold” forming recently added punch-in-place bottle removal for greater accuracy of bottle lips. Illig hasn’t sold the technology commercially, but says it is in discussion with packaging companies both in Europe and in the U.S.
Against this backdrop of highly imaginative but ultimately not commercialized R&D, a small startup company in France actually patented, built, and sold machines for what are believed to be the first commercial thermoformed bottles. Agami Technologies in Trappes, France (www.agami-tech.fr), which started in 2009, developed patented film-to-bottle machinery called Roll ‘N Blow (European Pat. # EP 2321113), which doesn’t use tooling undercuts and reportedly saves 30%-50% in material over extrusion blow molding.
The process starts with thin sheet for thermoforming and slits it in the machine direction into strips. The strips are shaped around blow air pipes into cylinders and welded along the open seam to make tubes. Tubes are heated and blown into bottle cavities at low pressure (under 6 bars) and under 150 °C. Because Agami forms bottles from a continuous tube of sheet, not by deep drawing flat sheet, bottle height isn’t limited, and no undercuts are needed. The process can potentially use standard blow mold tooling if the size is right.
The technology is used commercially to make 50-300 ml bottles at 7000-20,000 bottles/hour depending on size and shape, but it could make up to 500 ml bottles, Serac says. Bottles can have foil lids or screw caps and are shrink labeled. The film can also be preprinted before it’s made into bottles.
Serac Group SAS in La Ferte Bernard, France (www.serac-group.com), a maker of filling and capping machines, initially bought 10% of Agami along with worldwide distributions rights to the machines, which Serac introduced at Interpack in 2011. Serac has sold five machines since, one with two cavities to a U.S. firm for R&D, two machines with four cavities for commercial production in Europe making portion yogurt bottles, and two machines with six cavities, which are being built for a European customer for full production of yogurt bottles. Bottles are made commercially from PS and PP sheet. They could presumably be made from HDPE and PLA sheet too, but these haven’t been tested yet. Six months ago Serac acquired 100% of Agami and plans to introduce the technology for the first time in the U.S. at NPE (www.npe.org) in Orlando, FL, next March.