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06.05.2010 - Ecology through one-piece cap design
Two-piece caps, on the other hand, are manufactured in four operations: impact extrusion, cutting and folding of the tamper-proof band and insertion of the liner. Along with the required investment, this incurs the associated assembly costs and energy consumption. Moreover, the quantity of raw material (and the cost of raw material) is lower for one-piece caps than for two-piece ones.
And the recycling of pure HDPE is easier and more energy-efficient than the conditioning of multi-piece polypropylene caps with liners made of EVA.
Plastic caps for products hot-filled in PET bottles are at the moment almost all made from temperature-resistant polypropylene and are fitted with a separate liner. Corvaglia began the development of a one-piece cap in HDPE four years ago.
Using a newly-developed geometry the two-start 38mm cap, when it has been screwed onto the bottle, has sufficient pre-tension to form a perfect seal, which is actually reinforced by the distortion of the cap under vacuum. This solution for a one-piece HDPE cap allows considerable cost savings in comparison with the previous PP cap and separate liner. "Using the one-piece Corvaglia hot-fill cap it is possible to achieve cost savings of over 30 percent," said Romeo Corvaglia, managing director of Corvaglia Holding AG.
All of these innovative developments are possible only in close collaboration with the bottlers and sometimes even with the end customers, who also want to use their packing to achieve further savings in raw materials and energy and also, of course, on the cost side.
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