RECYCLING | PVC
The PVC processing challenge
US compounding systems group Farrel Pomini says processing PVC can be a challenge as it is heat sensitive by nature, its processing temperature window is narrower than many polyolefins, and if exposed to extended residence time or overheat- ed will degrade quickly and release hydrochloride acid, which is toxic and highly corrosive to the processing equipment. “The degradation will affect the colour and mechanical properties of the product,” the company says. Processing recycled PVC is an even bigger challenge because of its unknown thermal history and the contaminant invariably carried by the recycled material.
Temperature control Farrel Pomini says its Compact Processor (CP) II series is designed with the Farrel Continuous Mixer (FCM) technology that maintains precise temperature control which results in lower temperature mixing and a wide processing window for
both rigid and flexible PVC. The precise temperature control also provides higher production rates and lower costs due to a reduced need for heat stabilisers. Its CP series, offered in six models and able to provide PVC compound- ing at nominal production rates from 170 to 3,000 kg/hr for rigid PVC, and rates from 250 to 4,700 kg/hr for flexible PVC, feature multiple tem- perature control zones and rotor cooling which allows for processing of PVC within its ideal temperature range and with less reliance on heat stabilisers. The units also feature energy-efficient atmospheric venting for removing air, volatiles, and moisture from the mixer. The FCM utilises a twin rotor design that compounds materials in a single step rather than a melt, add, mix, convey, repeat technology associated with twin-screw extruder technology, says the company. Mixing is achieved by repeated passage of the compound through
and longevity. It also concluded a mass flow analysis with German association member KRV to find out the potential non-collected volume, which can help to set the baseline for future pilot collec- tion, sorting, and recycling projects for end-of-life plastic pipes at national levels from 2025 onwards. PVC compounder Benvic has been improving its in-house recycling, an activity that it started in 2019. Investment in 2024 increased the capacity and capabilities, through integrating an automated sorting process which will allow better screening and assist its technology for producing more homogenous secondary raw materials. Incoming and outgoing measurement ensure that production is fully compliant and certified by customers with regard to the regulation of legacy additives, especially lead content. Benvic’s approach provides new solutions to its customers, reintroducing secondary raw materials to compounds. Testing and quality schemes allow QB34 certification upon demand. Recognising the complexity of post-consumer feedstocks, the Benvic strategy combines recycling and develop- ing technology blocks depending on end-use
32 PLASTICS RECYCLING WORLD | January/February 2025
the controlled shear region formed by the rotor tip and the inner housing walls, as well as the continuous splitting and recombination of the compound between the two rotors.
Good dispersion Large rotor tip to wall clearances and non-intermeshing rotors allow for processing of abrasive materials and contaminants without excessive wear to major machine components. The unit’s #15/7 rotor combination provides good dispersive mixing with excellent distributive mixing and yields decreased melt temperature with increased production rates. Farrel Pomini has presented several case studies in which various recycled PVC materials in the form of a clear film, Luxury Vinyl Tiles, window frame, vinyl siding or shredded carpet tile backing, and containing a high percentage of solids/fillers or mixed durometer materials could be pro- cessed into a homogenous compound. �
www.farrel-pomini.com
applications. Such technology blocks are also geared to optimise the whole life cycle assessment. It has integrated this expertise so that it is now part of the design phase, which leads to risk reduction. Benvic points to a third-year gold rating in the Ecovadis scheme as proof of its successful ap- proach.
Vinyl flooring The European Resilient Flooring Manufacturers’ Institute (ERFMI) is advancing projects relating to the recycling of PVC flooring and PVC from bulky urban waste. With the support of VinylPlus Italia, the group commissioned Phoenix RTO, a Padua, Italy-based optical instrument, and systems maker to design and build an industrial technology capable of separating PVC from other plastics in post-consumer waste. Phoenix RTO developed a handheld device that employs near-infrared (NIR) hyperspectral technol- ogy that reduced the percentage of impurities in the collected PVC from an average of 3% to less than 1%. In 2023, it was asked to conduct further studies on PVC recycling based on scanning
www.plasticsrecyclingworld.com
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