direct extrusion | machinery feature
leistritz and Kuhne used their recent direct Extrusion day to discuss and demonstrate the progress that they have made in integrated lines for pET film and sheet production
direct action for film and sheet
Leistritz and Kuhne are combining their expertise in compounding and film extrusion to offer lines for the direct extrusion of film and sheet. The two german companies discussed their latest developments and demonstrated a working line at their direct Extrusion day, which was held at leistritz’s factory in nuremberg, germany, in november 2011. cast films are typically produced using a single-
screw extruder. in the case of pET, the material needs to be pre-dried prior to processing. By using a twin- screw extruder with vacuum venting, it is possible to remove moisture during processing. This can eliminate the need for pre-drying the resin. direct extrusion also removes the need for a pelletizing step and the materials have one less heat and shear history, which improves the quality of the finished product.
Direct benefits Kuhne and leistritz highlighted a number of advantages of the direct extrusion route for producing pET film. From an environmental point of view, energy savings of 35% are claimed compared to using a single-screw, while a twin-screw can handle 100% recycled material and pET flakes. There are further advantages in terms of product quality, including very good optical properties of the finished film because of the excellent mixing perform- ance of a twin-screw and the shorter residence time in the extruder unit. less stress is placed on the material
www.compoundingworld.com February 2012 | compounding world 47
and processing can be carried out at lower tempera- tures, leading to less polymer degradation. Both Kuhne and leistritz also emphasized the
process flexibility provided by the direct extrusion route for different coextruded structures and for handling other materials in addition to virgin and recycled pET. it is also possible to process pET/pE reclaim blends or produce highly filled pp/pE sheets, for example containing mineral fillers or wood flour. other process benefits include the optimised film
feed to the roll stack, which increases cooling capacities and provides better ergonomics for operators.
Direct extrusion allows recycled PET to be
processed without
pre-drying The direct
extrusion line is demonstrated
at the Leistritz factory
s
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56