HDPE plastics from post-consumer flows

Recycling service provider Interzero has developed a process to significantly improve how HDPE plastics are reused. Its patented process allows the viscosity of the recycled material to be controlled; it consequently allows blow-moulded products to be manufactured using 100% light packaging material sourced from post-consumer flows. This material had previously only been suitable for use in extrusion processes.

A chemical modifier controls the viscosity of the recycled material during the mechanical recycling process, i.e. a special combination of additives modifies the flow properties of the recycled high-density polyethylene (HDPE) during processing in such a way that they become comparable with those of virgin plastics. This option allows a leap from the previous extrusion quality to a quality that's suitable for blow-moulding and that may be used to manufacture bottles. The effort required for re-sorting waste polyethylene lightweight packaging, such as the types of waste disposed of in yellow bins in Germany, is eliminated as is the need to add primary plastic that meets the so-called PCC (post consumer commercial) or PIR (post industrial) classifications.

The patented process was developed at Interzero's Centre of Excellence for Plastics Recycling in Maribor, Slovenia. This centre is the only research facility in the EU that possesses government accreditation in accordance with the ISO/IEC 17025:2017 laboratory standard and that has specialised in the development and analysis of recycled plastics. "We're able to draw on many years of experience and expertise in the development and analysis of plastics at this location," explains Markus Müller-Drexel, CEO at Interseroh+, which is Interzero's recycling alliance.

The laboratory has developed steadily in recent years and is now entering the market with an expanded range of services. Five laboratories that boast modern technical equipment that's used for assessing material qualities – from mechanical, thermal, chemical and rheological properties to migrations, sensor systems and colour – are also equipped with material-processing machines and an NIR separator for simulating the behaviour of packaging during sorting.

The new development delivers significant savings in virgin materials and thus in petroleum and CO2 emissions for Interzero and its customers. The energy saved during sorting also means that CO2 emissions are even further reduced. This means better utilisation of the capacities at sorting plants in the face of ever-increasing volumes of used packaging. Manufacturers are also able to keep the standard equipment that they use to make new recycled products using blow-moulding processes.

Slovenia-based Rupar Plastika is one of the first companies to take advantage of the new process. The company manufactures hollow plastic parts, including bottles and closures, for well-known manufacturers and employs a range of different plastic processing technologies, including extrusion blow-moulding, injection stretch blow moulding, injection blow moulding and injection moulding. "It's often necessary to adapt production lines to the use of new types of plastics. Interzero's new process means that such modifications are no longer required. That's both a huge time and cost benefit," says Rok Miklavčič, Head of Production and Sales at Rupar Plastika.