MACHINERY | MIXERS
consumption, Marinello says. It has an output of 9,600kg/h, based on eight batches/h of dry blend. The cooler is engineered to receive up to 1,500 kg/ batch of CaCO3
filler.
Above: Entex sees its
continuous PRE mixing system for PVC as an effective alternative to batch mixers in volume production
control while a remote maintenance module allows troubleshooting by Mixaco service staff.
Powerful blending Promixon was promoting its XM turbo mixer, which the company considers to be “one of our most innovative and powerful systems, capable of blend- ing at any speed while maintaining a high level of performance and reducing usage problems.” Promixon says the XM turbo mixer “lasts longer, is more productive, and is less of a burden on finances.” The company says requirements from customers for faster intervention to tackle production prob- lems, as well as calls for changes or upgrades on production automation of production, have reached very high levels in recent years. “The accurately-studied automation system provided on our machines, united with a remote connection, helps our customers to reduce risks of non-compli- ant material due to human error and drastic reduction of machine downtimes, with prompt intervention in very short time by our specialists,” according to a company spokesperson. Company president Marco Marinello also spoke
of its successful bid for what he says was the biggest single mixing plant ever produced. The contract, for a US producer of luxury vinyl tiles, included an XBlend-MC/2500/8600 system comprising an XM-2500 high speed heating mixer and an XC-8600 horizontal cooler XC-8600. The unit was customised to variable filling level and to process a wide range of formulations, oriented to the reduction of mixing time and minimal energy
64 COMPOUNDING WORLD | November 2019
Continuous options Meanwhile, Entex Rust & Mitschke says its Planetary Roller Extruder (PRE) provides an interest- ing alternative to the traditional approach of making PVC compounds via discontinuous produc- tion of dry blends with hot and cold mixers. When used in a direct compounding configuration (see schematic) the continuously-running equipment has a higher investment cost, but as Thomas Birr, Head of Process Engineering at the company argues, this can be recovered by lower running cost (energy consumption is said to be much lower). In the Entex solution, raw PVC is dosed into the PRE with the stabiliser system added in parallel as a separate component. Diffusion of the liquid components into the PVC, which normally takes place in the discontinuous process in an internal mixer, takes place mechanically in the PRE through a combination of friction and pressure as the liquid components are rolled over the solid PVC. To some extent, the direct PVC compounding PRE mimics hot and cold mixing. The PRE compris- es two modules: the raw material is melted, dispersed and homogenised in the first before passing directly to the second, where temperature and pressure are significantly lower. Although this process is accompanied by some heating of the polymer, thermal damage is prevented by the short dwell time of the melt in the high temperature zone. “Examinations of the extrudate have shown that the thermal damage of the polymer in direct extrusion is usually even lower than in the tradi- tional dry blend method,” claims Birr. Entex says that total residence times in hot and cold mixers are several minutes, while in direct compounding can be under one minute. Entex has been proposing this mixing approach for some time, but Birr says interest has recently picked up, especially for greenfield operations. He estimates there are up to 20 PREs currently being used for PVC direct compounding around the world.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.coperion.com �
www.mti-mixer.de/en �
www.zeppelin-systems.com �
www.plasmec.it �
www.mixaco.com �
www.promixon.com �
www.entex.de
www.compoundingworld.com
PHOTO: ENTEX RUST & MITSCHKE
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