Plastics: with PRINCE recycling is more efficient and economical than rPET

Recycling plastic waste more efficiently and at a lower cost, in particular PET (polyethylene terephthalate), with benefits for the economy and environment.

This is the ambitious and highly relevant result of PRINCE. This is an innovative project of excellence among the 33 winners of the Call Hub Research and Innovation of Lombardy Region, and for this reason financed with over EUR 2.8 million of POR FESR 2014-2020 funds (out of a total project value of EUR 5.2 million).

The response to a specific need

The PRINCE project (acronym for PET – Re-polymerization Italian Network Compact Extrusion) pursued an objective in line with circular economy policies and with the adoption of the European strategy for plastics: that is, a major improvement in the process of recycling PET used for bottles (one of the most recycled types of plastic) thanks to a more efficient recovery on the recycled PET (rPET) market in the form of finished industrial products.

The demand for rPET has been increasing for some time. The trend is reinforced by the EU Sup (Single-use plastics) directive, with which the European Union has prohibited the sale of single-use plastics.

Specifically, according to the promoters of PRINCE, the market analysis of rPET and its future prospects indicates that most of the products will originate from non-clear flakes, which are more economical than the clear ones as well as available in larger quantities. Precisely those used by the PRINCE project.

Current technologies for recycling this particular material carry significant costs, even higher than for virgin polymer, and times that do not meet the demand for this secondary material.

In other words, to now a sufficient industrial capacity has not existed to guarantee - in Italy and in Europe - the production of volumes of rPET enough to meet demand. This is also due to the lack, upstream, of an efficient system of collection and selection of the different types of plastic, for example clear and non-clear plastics. These non-clear plastics essentially comprise most of rPET.

The innovation

To optimise the recycling process, the PRINCE project encompasses development of a pilot line that - by significantly reducing the limitations of the single-screw extrusion process related to the components of the reactive process between the oligomeric segments and the polymeric chains of rPET-  enables production of a multitude of finished industrial products, starting with non-clear rPET flakes obtained from bottles post-consumption.

The pilot line was installed and tested together with a variety of processing technologies (downstream), which allowed production, starting with rPET flakes from bottles, of five finished products: strapping for packaging, filaments for textiles, extruded products for construction, sheets, and containers for non-food liquids.

Among the benefits is a significant overall cost containment, especially due to energy savings: the partners of PRINCE have estimated a reduction of about 30% compared to conventional lines - and a more efficient management of water resources-air-production waste.

The partnership

PRINCE was set up through the alliance of a Research Organisation - the lead Istituto Italiano dei Plastici, specialising in system/product certification of the plastics supply chain, an inventor of innovative technologies in the processing of thermoplastic polymers, and six manufacturers of machinery and equipment for plastics.