MATERIALS | WIRE AND CABLE
IMAGE: COPERION
Above: Coperion’s two-stage Kombiplast system is used for PVC and specialty cable compounds
suitable for buffer tubes. The company says being a global supplier to the
wire and cable industry means having both halogenated and halogen-free compound exper- tise. “We are often asked why the US industry has not switched from PVC to HFFR polyolefins on the scale that Europe has,” says Saggese. “We believe the answer is related to several factors that, combined, present considerable challenges to the adoption of halogen free solutions in the North American market. These challenges include a fundamental difference in how the two continents view fires and flame spread; the presence of the ‘Wet IR’ test in the UL44 North American standards; and, the historical expertise and equipment infrastructure in North America, which exposes the temperature sensitivity and run speeds of zero halogen containing compounds.”
Below: Upgrades to Coperion’s EGR pelletising system
enhance pellet quality and reduce fines, shown in the right image
Combined benefits German machinery maker Coperion developed its Kombiplast KP two-stage compounding system for production of PVC and specialty compounds such as those used in the cable sector. It combines a twin screw extruder from the company’s highest performing ZSK series with a single-screw ES-A discharge screw, which provides gentle pressure build-up for shear-sensitive products. The latest developments of the KP system are focused on maximising product quality and improving handling of the equipment. For exam- ple, the company recently modified the ES-A screw design to provide a more uniform and gentle flow and pressure build-up before the melt passes through the pelletiser die plate. The result is said to be very uniform and high quality pellets.
Coperion also recently developed a new knife rotor for its EGR eccentric pelletising system, which makes it possible to produce extremely low-dust PVC pellets for cable compounds. Rotating directly on the die plate and using knives made from a specially-developed alloy, the rotor allows particularly
smooth and gentle cutting of the polymer. “Due to these technical optimisations the knives
remain in particularly even contact with the die plate during operation,” says Maria Hölzel, Head of Team Engineering Plastics EP2 Process Technology at Coperion. “The result is very high cutting quality that forms the basis for achieving the desired substantial reduction of the proportion of fines in the pellets.” The EGR knife blade system has also been modified so that the knives can be pre-assembled outside of the system then simply inserted to avoid down time. The pre-assembly is matched to the respective die plate. Coperion says it is currently working on devel- opment of an alternative system for pressure build-up in production of demanding HFFR cable compounds. “The aim is to significantly minimise the time-consuming cleaning required by the units normally used. At the same time, the new system will ensure a very stable pressure build-up, espe- cially in the preparation of highly viscous, some- times very sticky formulations,” according to Hölzel.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.prysmiangroup.com �
www.avient.com �
www.adeka.co.jp/en/ �
www.lubrizol.com �
www.teknorapex.com �
www.hubermaterials.com �
www.alphagary.com �
https://viscospeed.com/en/ (Innospec) �
www.ipoolsrl.com �
www.sacoaei.com �
www.coperion.com �
www.hubermaterials.com
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COMPOUNDING WORLD | May 2022
www.compoundingworld.com
IMAGE: COPERION
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