A novel injection molded plastic closure is adding a finishing and value-enhancing touch to that most traditional of beverage containers, the metal can.
When plastics companies think about beverage packaging, metal cans are usually viewed as a competitive threat. However, metal packaging can present an opportunity, with plastics capable of delivering innovative new features to even the most established packaging formats.
Ball Packaging Europe Holding GmbH & Co. KG has caused a real stir in the can industry with its development of a multi-component injection molded plastic closure that provides easy resealability for still and carbonated beverages.
The Ball Resealable End (BRE) took five years to develop and is the can industry's first resealable closure.
The first beverage company to adopt the technology was Coca-Cola Co., which is using the closure on a 500 mL (16.9 ounce) aluminum can for the Burn energy drink that it launched in 2008 in France.
Coke's market research revealed that consumers considered the resealable can to have more appeal than a standard design and that BRE helped Burn stand out from its competitors.
“The resealable end marks a major advance in beverage packaging and the French ... understood it: They all welcomed the innovation with enthusiasm,” said Vincent Bouin, marketing manager at Coca-Cola France.
The BRE is an aluminum can end into which a flat opening mechanism incorporating injection molded plastic parts is attached. The closure consists of an outer high density polyethylene cap, which engages a two-component polypropylene inner element containing a screw mechanism and a thermoplastic seal. A simple twist of a molded-in “wing” uncovers the drinking opening. The closure is retained with a PP locking ring.
All this means that the BRE can retain the classic beverage can shape and its associated ability to be stacked, which is a logistical advantage for transportation and retailing. As only a small amount of plastic is used, it does not significantly affect recycling of the can — an important benefit as standard beverage cans can easily be sorted and recycled using existing infrastructure.
The tamper-proof feature of a traditional ring-pull can also is retained, enabling consumers to easily verify that the seal has not been broken before the can's first opening.
The BRE closure concept was the brainchild of Antonio Perra at design firm 4Sight Innovation BV and its subsidiary Bound2B BV in Alkmaar, Netherlands, which developed the product with Ball Packaging Europe, the Ratingen, Germany-based subsidiary of Ball Co. of Broomfield, Colo.
Development of the BRE focused on satisfying a number of demanding user requirements. It had to be easy to open, while also eliminating leakage and safely retaining and managing internal pressure.
A special feature of the BRE cap design is that the twist-open movement releases the sealing valve before the can's opening is exposed, allowing any pressure inside to safely escape.
The production system for the closure was developed by Bound2B and Ball Packaging Europe, together with injection machine maker Ferromatik Milacron Maschinenbau GmbH of Malterdingen, Germany, mold maker Foboha GmbH Formenbau of Haslach, Germany, and Hekuma GmbH, the automation supplier from Eching, Germany.
BRE caps are manufactured on a 64-cavity-cube injection molding and assembly system that's designed to handle a line speed of 384 ends per minute — equivalent to an estimated annual capacity of around 150 million ends.
Dr Jšrg Dassow, director of marketing at Ferromatik Milacron, says the production cell uses a combination of single- and double-cube production technology on two molding machines in an integrated cell. Cube mold production technology uses four-faced molds mounted on a carrier inside the injection molding machine, which allows the mold to be indexed around the vertical axis between cycles to present four individual mold faces in sequence.
Different functions can be performed at each mold face on each machine cycle — molding, cooling, printing and label inserting, for example — with the option to stack two cube molds together to provide more flexibility for the production system designer.
The BRE production process uses a five-axis robot to feed blank aluminum end shells to a forming station where the metal can end blank is shaped. The metal insert is then placed in the first cube in a double-cube mold, where the PP locking ring is molded in place. At the same time, the inner plastic closure and sealing element is molded in two steps on a machine in a single-cube mold, where it is pressure tested. The inner closure is then transferred to the second cube in the double-cube system, where the final overmolding and assembly operation takes place.
Finished assembled parts are removed from the twin-cube machine, with the final step being application of an adhesive label that carries instructions and prevents the risk of contamination during the filling process.
In a November presentation at EPN's Plastics Caps & Closures conference in Brussels, Dassow said that making the closure using conventional molding technology would have required three machines and much more complex automation.
The BRE was awarded Can of the Year for 2008 by The Canmaker. John Nutting, the magazine's editorial director, said the can industry has been “waiting for years” to see the commercial application of a resealable lid on a drink can.
