Extrusion International 1-2022

50 Extrusion International 1/2022 SHEET EXTRUSION KraussMaffei promotes research project Within the frame of this project, KraussMaffei’s extru- sion division actually succeeded in matching the phenolic compound formulation and the process control in order to be able to extrude boards with low density, high me- chanical stability, low thermal conductivity and good fi re resistance on a co-rotating twin-screw extruder. “The ex- cellent fi re properties of the new thermoset foamboards are indeed something very special,” declares Andreas Madle, process engineer in the Process-Engineering De- velopment Division and project manager at KraussMaf- KraussMaffei Extrusion GmbH An der Breiten Wiese 3-5, 30625 Hannover, Germany www.kraussmaffei.com Cross-Linked Foam Boards Produced on ZE BluePower Extruder ZE 42 Blue Power twin-screw extruder optimally adapted to the process keeps crosslinking in the extruder under control In its capacity as one of six associated partners, KraussMaffei has promoted a joint cooperation project funded by the German Federal Ministry for Economic Affairs and Energy (BMWi). The common aimof the project partners was to develop a closed value- added chain for thermoset rigid phenolic foam – starting from the production, through planning, construction and operation up to material recycling. The highly innovative rigid foamproducts are ideal for the use as load- bearing insulating composite components in the building sector, e. g. for mounting solar modules or air-conditioning systems on roofs or for the installation of windows, railings or awnings to the building façade fei. Even without the addition of fl ame retardants, the newmaterial is extremely fl ame resistant and hence clas- si fi ed as fi re protection class B1. Optimally con fi gured twin-screw extruder keeps cross- linkage under control The ZE 42 BluePower twin-screw extruder available in KraussMaffei’s R&D center in Hannover was used for the production of the foam boards with a thickness of 50 mm. In terms of process-engineering characteristics, this extrud- er was precisely adapted to the requirements of the mate- rial processed. “The challengewas to keep the cross-linking process in the extruder under control and to avoid the for- mation of dead spots,” says Andreas Madle. This goal has been achieved through a low-shear screw geometry, mod- erate processing temperatures ranging between 100 and 120°C and the selection of a screw tip that is characterized by an extremely reduced free volume. The fi nal product is a thermoset foam with a density of about 800 kg/m 3 and a good thermal conductivity of 0.12 W/mK. “We are well aware of the fact that our foam is rather heavy compared to thermoplastic foam such as EPS, which can reach densi- ties of less than 30 kg/m 3 ,” states Andreas Madle and adds: “However, these two foam products are not really com- parable as their fi elds of application are completely differ- ent. In fact, the new foam is intended, among others, as an insulating material for loaded applications and the higher mechanical stability involved inevitably requires a higher density.” Furthermore, the process engineer is convinced that future research and development projects will allow the density of phenolic resin foam to be further reduced. The other cooperation partners involved in this project were Hexion GmbH (phenolic resins), Ejot Baubefestigun- gen GmbH (fastening solutions for the building industry), Schöck Bauteile GmbH (load-bearing insulating compo- nents) as well as Robert BoschGmbH (various products and consumer goods). The project has been coordinated by Chemnitz Technical University, Faculty of Mechanical Engi- neering, Chair in Plastics. Phenolic resin panels are particularly suitable for the stable fastening of photovoltaic systems Energy-ef fi cient phenolic rigid foampanels feature low density with highmechanical stability, low thermal conductivity and good fi re properties