Bekum: Tri-Extrusion and Retrofit Solutions Address PPWR Requirements in Extrusion Blow Moulding

Production examples – Extrusion Layer Graphic - (Graphic: Bekum).

The EU Packaging and Packaging Waste Regulation (PPWR) is increasing the pressure on plastic packaging manufacturers to adapt their production processes. Design for recycling, higher recycled-content targets and more efficient use of materials and energy are set to become increasingly important. In extrusion blow moulding, this is creating new technical challenges, particularly when it comes to processing post-consumer recyclate (PCR).

Compared with virgin resin, PCR can vary considerably in viscosity, melt flow rate, colour and contamination levels. These fluctuations can affect plasticising performance, melt flow and overall process stability. The challenge is therefore not simply to process recyclate, but to do so reliably while maintaining consistent product and packaging quality. This requires the extruder, extrusion head and process control system to be engineered as a coordinated unit.

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One way of increasing recycled content is tri-extrusion. In this configuration, three extruders feed different materials into a multilayer extrusion head. A typical structure uses defined materials for the inner and outer layers, with PCR forming the core. Virgin resin can therefore be used selectively where it is needed for surface quality, barrier properties or other functional requirements, while recycled material accounts for the largest possible share of the remaining structure.

Production examples – Tri-Extruded Canister Sample - (Photo: Bekum).

For canisters, bottles and technical hollow parts, this approach can reduce the use of virgin plastic without making overall product performance overly dependent on variations in the recyclate. The extrusion head is particularly important in multilayer applications, as it determines the distribution and stability of the individual material layers.

Production examples – Tri-Extrusion Head Type 3BKW55-3 with Vertical Extruder for new machines and upgrades on existing machines - (Photo: Bekum).

Bekum cites its 3BKW55-3 multilayer extrusion head as one example. Designed for tri-extrusion applications, the system uses two vertically arranged extruders. According to the company, this vertical layout makes it easier to integrate additional extrusion units where space is limited, which can also make the concept suitable for retrofitting existing machinery.

Bekum says that converting to multilayer production does not necessarily require investment in a new extrusion blow moulding machine. Depending on the machine type, existing extrusion equipment, available space, required throughput and application, mono-extrusion systems can be upgraded with additional extruders and a suitable multilayer head. This can, for example, enable PCR to be incorporated as a core layer.

Retrofitting is particularly relevant for machines whose mechanical and electrical infrastructure still provides sufficient capacity. The existing system must offer enough installation space, support the required throughput and allow the additional extrusion components to be integrated. Where these conditions are met, manufacturers can adapt their installed machinery to new material concepts and packaging requirements without replacing the entire production system.

Material efficiency is another area of growing importance. Bekum points to technologies such as its HiPEx extruder series, wall-thickness programming and multilayer concepts. These approaches are intended to place material only where specific properties such as strength, barrier performance or surface quality are required, allowing part structures to be designed more closely around their functional needs.

As PPWR requirements are phased in, flexibility is likely to become an increasingly important feature of extrusion blow moulding equipment. Tri-extrusion allows different material streams to be combined and can support higher PCR content in packaging. At the same time, retrofitting existing systems offers manufacturers an alternative to investing in entirely new machinery.

For both machine builders and processors, the interaction between extruders, multilayer heads, material handling and process control is therefore becoming a key factor in implementing new recyclate strategies and improving resource efficiency.

More information: www.bekum.com

Bekum Maschinenfabriken GmbH, Berlin, Germany

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