KraussMaffei Berstorff GmbH

KraussMaffei Berstorff extends its product portfolio by two extrusion concepts for plastics recycling

Compounding of used agricultural film, production scraps generated during sheet production as well as of fiber residues into top-quality compounds
– Single or double-stage extrusion process for customer-specific compounding applications
– High-quality waste material based compounds produced in a single heat
(Hannover, 12th June 2013) KraussMaffei Berstorff offers two new extrusion solutions for sorted plastics recycling. The new extrusion lines are designed for converting washed plastics waste with high residual moisture content to high quality reclaim or compounds in a single heat. Focus is placed on eco-friendly and economic single and double-stage processes with a twin-screw extruder as core component tailored to specific customer requirements.

Single-stage recycling concept for free-flowing and damp waste material
“The characteristic feature of the single-stage variant is the purely mechanical squeezing of the water from the plastics waste on the twin-screw extruder;” explains Martin Mack, Vice President Research and Development at KraussMaffei Berstorff in the USA. Free-flowing PE or PP agglomerates are washed and subsequently fed into the twin-screw extruder with a water content ranging between 5 and 20 percent. Even before the plastic material melts, most of the water is removed in axial direction by the pressure built up in the compression zone. The remaining moisture is released in the downstream zones equipped with atmospheric and vacuum degassing. The product hold-down device prevents the melt from rising into the degassing openings of the twin-screw extruder, so that the degassing process is not affected and the melt residence time is not increased. When substantially contaminated starting material is processed, the twin-screw extruder can be equipped with an additional melt filtering system installed upstream from the pelletizing unit. If the pellets produced are not intended for direct further processing or recycling, they can be subsequently refined in a separate compounding process.

UltraFeed system for improved feeding of light-weight recycled film and sheets
The optional package composed of an enlarged 6D feed opening and a special screw configuration with increased volume for light-weight shredder and film reclaim gives substantially higher output rates for materials with low apparent density.
The proven UltraFeed system provides additional potential to boost output rates. The suction insert installed in the special feed housing compresses light-weight film chips and increases the feeding capacity by up to 30 percent.

Double-stage recycling and compounding processes for non-free flowing waste material
KraussMaffei Berstorff offers a double-stage process for used agricultural film, production scrap like edge trims generated during sheet production as well as for fiber residues. This process comprises a special single-screw recycling extruder and a twin-screw compounding extruder. “Direct production of a high-quality compound in a single process is the main benefit of this solution,” explains Ralf J. Dahl, Head of the Twin-Screw Extruder Division at KraussMaffei Berstorff in Hannover.
In the single-screw recycling extruder with upstream cutter compactor, the material is prepared for the double-stage extrusion process. After having been broken down and dried by friction heat, the washed reclaim material with a moisture content of up to 10 percent is led from the cutter compactor to the single-screw extruder. Here, the material is plasticized, homogenized, degassed and filtered by means of a high-performance superfine melt filter.
A gear pump with constant pressure and volume ensures volumetric metering of the reclaimed and clean melt into the twin-screw extruder either from the top or from the side. The melt can be provided with various fillers and is then compounded.
The twin-screw extruder is also designed to incorporate virgin material in the form of pellets, which means that it can additionally be used as a pure compounding extruder.
The double-stage process benefits from the excellent compounding performance of the twin-screw extruder even with high filling degrees and offers a smart way of avoiding feeding problems with high-volume starting material as the material is already pre-dried and compacted in the cutter compactor/single-screw extruder combination. “Thanks to the central control system, this cost-effective compounding process produces top-quality compounds with high repeat accuracy,” Ralf Dahl explains.

High productivity
With the single-stage and the double-stage extrusion concepts for the conversion of damp plastics waste into high-grade final products, Krauss Maffei Berstorff offers optimum solutions for almost all compounding tasks with output rates of up to 4,000 kg/h. Both technically and economically mature processes can do without time and cost-intensive preparations like pre-drying or re-pelletizing. Compounding in a single heat ensures minor material degradation and excellent energy efficiency.

Trade press contact for the
KraussMaffei Berstorff brand (Hanover location)
Andreas Weseler
Phone: + 49 511 57 02 586
Fax: + 49 511 57 02 608
E-mail: Andreas Weseler@kraussmaffei.com