MACHINERY | ALTERNATIVE EXTRUDERS
continued growth of recycled materials and other temperature sensitive materials, which are well suited to continuous mixers,” says Paul Lloyd, Business Unit Director. “Farrel continuous mixers excel at
processing highly filled and temperature sensitive materials. Our principle applica- tions include highly-filled compounds, white and black masterbatch, flame retardant compounds, PVC and flooring.
IMAGE: CPM EXTRUSION GROUP
Above: This rPET produc- tion line for food-grade resin uses a CPM RingEx- truder RE and has FDA and brand-owner approvals
Right: The good degassing performance of the
RingExtruder RE is related to its high surface/ volume ratio
extruders, which can be met using RingExtruder RE technology.” Chemical recycling is likely to require residence times beyond the limits of twin-screw extrusion machinery to become a commercial reality, he says. And scaling-up of reactive extrusion applications such as TPV and TPU polymerisation also becomes a challenge due to the decrease in surface/volume with larger diameter twin-screw extruders and the associated heat-transfer limitations. These applica- tions could be successfully accomplished with the RingExtruder RE but Dreiblatt thinks it will take some time for commercial acceptance of what is, at present, an unfamiliar technology. Improved energy efficiency may help win that acceptance. “While energy consumption in compounding is not a problem today, the ‘green’ revolution will demand reduced energy in the future. This will particularly impact resin producers with twin-screw production lines and high capaci- ties of more than 5 tonnes/h, more than the small-to-medium sized compounders, Dreiblatt says. “As the cost of electricity will most likely increase in the future, RingExtruder RE technology will become more viable for high capacity com- pounding simply due to the reduced energy cost.” He adds that CPM is currently increasing the torque density of the RingExtruder RE to allow higher production rates for a given machine size, which will further reduce operating costs.
Continuous demand
Demand for continuous mixing equipment is increasing due to the ongoing growth in key application market areas as well as the increased pressure on compounders to utilise the most efficient technologies, in particular with regard to energy, according to Farrel-Pomini. “In addition, today’s compounding challenges include the
20 COMPOUNDING WORLD | October 2020
www.compoundingworld.com
Many of the world’s leading flooring brands utilise Farrel Pomini equipment. Our activity level with processing biodegradable plastics and recycled materials has also increased significantly,” he says. The company’s continuous mixing technology is based on two counter-rotating, non-intermeshing rotors and a large free volume mixing chamber. The large mixing chamber is said to allow liberal material circulation and good distributive mixing, while the specialised rotor geometry enables efficient levels of shear and very good dispersive mixing. Other features include incorporation of a single large feed port that allows for introduction of high filler loadings and irregularly sized materials. Farrel Pomini says mixing intensity can be adjusted by making changes to rotor speed, working volume, thermal conditions and orifice position. In addition, the standard 6 L/D mixing unit ensures a short residence time and a low heat history for the polymer while still providing a high-quality homogeneous mixture at the exit of the processor. Modular components allow for easy maintenance and greater production time. The company says that it sees processing of
recycled materials and biodegradable plastics as a significant trend that will dominate the compound- ing industry as environmental concerns continue. “Continuous mixing technology is adiabatic in nature and does not impart additional heat or energy into the compound,” says Lloyd. “This is
IMAGE: CPM EXTRUSION GROUP
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