Not Just Hype, but Proven Practice: Twin-Screw Extrusion for Cast PP Films
Twin-screw extruders have long been the standard in the production of cast PET film – well-known, proven, and indispensable. What is less well known is that cast PP (CPP) production also benefits from this technology – through greater efficiency and sustainability.
Twin-screw extrusion enables melt rates of up to 3,000 kg/h and has been used successfully in the CPP sector since 1999. Nevertheless, only a few producers are aware of its capabilities and advantages. It’s worth taking a closer look.
Film manufacturers are under pressure: As calls for greater use of recycled materials grow louder, line efficiency often goes down. Those who have to process low-quality material or high percentages of recycled content quickly reach the limits of conventional single-screw extruders. When the recycled content reaches about 25 percent
- the process becomes unstable,
- the number of gels in the film increases,
- and melt quality declines, making further processing impossible.
Reifenhäuser’s twin-screw technology solves all these challenges in the processing of post-industrial recycled material in PP flat film production with one stroke.
“With our twin-screw extruders and the complete systems optimized for them, we took direct extrusion and inline compounding to a whole new level years ago,” explains Mark Schuster, Head of Product Management at Reifenhäuser Cast Sheet Coating.
The advantages of Reifenhäuser's twin-screw technology for CPP production:
- Increase throughput: Melting capacity of up to 3,000 kg/h.
- Up to 50% PP regrind processing: Edge strips and regrind from scrap rolls can be processed directly as fluff (shredded film).
- Approximately 50% less energy consumption: The efficient shearing and mixing action, along with the elimination of energy-intensive regranulation, significantly reduce operating costs.
- Minimize changeover times: Quick net width changes without deckling – wider edge strips can be processed directly using the twin-screw extruder.
- Reduce material costs: Direct compounding with demanding mineral fillers is possible.
Reifenhäuser has consistently perfected the twin-screw principle through years of development. Thanks to the excellent mixing action of the co-rotating twin-screw, the melt is purified directly during the process under precisely defined and reproducible parameters. This makes the technology particularly appealing to those who also operate BOPP lines – they can feed their self-produced BOPP-PIR directly back into the material cycle and process it into new cast PP film.
Are you interested in twin-screw technology for CPP production?
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