TECHNOLOGY | THIN-WALL MOULDING


Above: Cups made with Bockatech’s EcoCore process start off with very thin walls and then expand with very fine foam as soon as the mould opens


potential licensees around the world are continu- ing (see also Injection World’s foam injection moulding feature, March 2019). Amaray is making its cups on a four-cavity


mould, built by FSG Tool & Die in Wales, which is a long-term collaborator with Bockatech. The next-generation moulds will have higher cavitation, possibly going up to eight including stack moulds. The process runs using PP with relatively high


melt strength, and which contains a chemical blowing agent (EcoCore is also developing a variant with a physical blowing agent). In 2018, Bockatech announced a strategic alliance on materials with Borealis, which is a leader in PP production and development. A similar strategic alliance with Verstraete, which provides PP in- mould labels, was announced at K2019. “The patented EcoCore


Right: Bockatech worked with Borealis to show cups were reuseable and recyclable


solution, in combination with Borealis grades BH381MO and Daploy WB140HMS [a high melt strength PP with long chain branching originally developed for foam extrusion], is an eco-friendly way to produce high-performance packaging that is reusable and recycla- ble,” said Borealis at the time. Foamed mouldings that use EcoCore require less material and have faster cycle times to reduce material costs, energy use and environmental impact. EcoCore runs on standard packaging grade injection moulding machines but requires investment in new moulds specially designed for the process. The trick with the process is in the opening of the mould immediately after injection. So, a part is originally moulded with a wall thickness of around 0.65-0.7mm, but when the mould opens, with the


A G E : B O C 20 INJECTION WORLD | March 2020


part still on the core (without the need for any core movements, unlike in the original version), this immediately increases in a highly controlled manner (partially due to the part’s external geom- etry) to over 2mm as the blowing agent does its work, with controlled expansion leading to production of a very fine cell structure. The result is a container that is light but very strong, and with excellent thermal insulation properties. Martin Blacher, in Marketing & Product Design, says EcoCore scores on several sustainability fronts. It uses less energy, less material, and less machine time than alternative processes. It can run on any high-end injection moulding machine set up for thin-wall packaging. “The innovative foaming technology produces skin-foam-skin walls in an instant,” says Blacher. “Cycle times for mouldings using EcoCore are the same as those made from solid plastic — up to 80% less than other foam core products. EcoCore mouldings also have a very high strength to weight ratio. Packaging produced with EcoCore is up to five times stiffer than solid mouldings of the same weight. Or, the amount of plastic required can be reduced by up to 70%.” Bockatech is aiming EcoCore at a variety of


packaging applications including beverages (e.g. take-out cups), food (e.g. noodle pots and micro- wave meals), industrial (e.g. pails, tubs and paint containers) and healthcare (e.g. medicine and sharps containers).


Injection moulding using a chemical blowing agent (which is the current practice for foaming) enables a minimum pre-foam wall thickness


of 0.65-0.70mm, which expands to around 2.1mm. Moulding with a nitrogen blowing agent is currently under develop- ment and will allow a minimum pre-foam wall thickness of 0.45-0.50mm, with a targeted final thick- ness of around 1.4mm.


CLICK ON THE LINKS FOR MORE INFORMATION: � https://stackteck.com � www.bmb-spa.com � https://trexel.com � www.kraussmaffei.com � www.arburg.com � www.sumitomo-shi-demag.eu � www.milacron.com � www.bockatech.com


www.injectionworld.com


IMAGE: BOCKATECH


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