machinery feature | pVc compounding
pVc, such as contamination or leakage. Buss recommends the next-generation Buss Quantec hot-face pelletizing system fitted with a screenpack in the die plate. This system can be provided with pellet
cooling with either air or water. The die plate functions as a breaker plate, and the screen- pack can be easily changed by swinging out the pelletizer, simplifying the challenge of melt filtering at low pressure. For pVc formulations which do not require
melt filtering, the Buss pressure-optimized die plate allows rigid pVc and highly filled
coperion’s Kombiplast is a two-stage system combining twin-screw and single-screw extruders
pVc, which is more difficult to compound. The increased residence time of the 15 l/d Quantec enables improved mixing with controlled shear and optimal dispersion so you can avoid gels,” explains irish. wire and plenum cable grades that contain high
percentages of temperature-sensitive flame retardants are another challenging compounding application that can benefit from the 15 l/d. “compounding of these grades requires excellent dispersion, controlled temperature mixing and good vacuum degassing,” notes irish. Such compounds also contain undispersable
particles from the mineral-based flame retardant that must be filtered out of the melt either by the com- pounder or the processor. irish notes that screen- changers can cause problems with melt filtering of
flexible grades to be processed at low pressure and temperature. This version is also ideal for high viscosity cpVc grades.
Pushing PVC coperion considers pVc compounding a core market, and in the middle of last year it organised a team of engineers and salespeople focused solely on pVc. The team is concentrating on optimising the company’s Kombiplast technology, and has been working with customers to identify and incorporate improvements. The Kombiplast is a two-stage system, with a ZSK
co-rotating twin-screw extruder that feeds – at atmospheric pressure or under vacuum – into a single- screw extruder that builds up pressure for pelletizing. The two-stage machine provides a more gentle treatment of the material as well as more precise
1 mixer (hot or hot + cold) 2 Twin screw side feeder Zs-b 3 polymers (eVa/pe) 4 additives 5 Flame retardant fillers (aTh) 6 liquids 7 Vacuum unit 8 pellet cooler
set-up for pVc processing set-up for hFFr processing
The hybrid KombiplasT sysTem can be swiTched To run boTh pVc and hFFr compounds 46 compounding world | January 2012
www.compoundingworld.com
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