Extrusion International USA 2-2022

55 Extrusion International 2/2022 PLASTIC PIPES temperature reduction of the melt. In the initial trials, Borealis’ HDPE HE3490 LS was used for a DN110 x 6.3 cable protection tube and foamed with nitrogen. After production of a non-foamed reference sample, the metered gas quantity was gradually increased, re- sulting in a weight reduction of up to 26 % for virgin material and approx. 15 % for recycled material – based on the entire pipe. The pipe produced in this way was subsequently tested in accordance with DIN 16876 and GA KSR 2010 (Switzerland) and was able to meet all re- quirements. Particular attention was paid to the ring stiffness and the drop test according to DIN EN 744. Based on these positive results, the test was repeated with a foamed inner layer made of recycled HDPE. This also showed good feasibility with a stable process. More sustainability through physically foamed cable conduits In view of the current supply situation for polymers and the ever increasing material prices, microcellular foam- ing of plastic pipes is a perfect way to save material and reduce the CO2 footprint for the pipes. In contrast to foaming with exothermic chemical blowing agents, no SVHC (substances of very high concern) listed additives are used and an accumulation of additives via regrind recycling is also avoided. Of course, this technology can also be used for other pipe systems. In the coming months, the joint tests of WEBER and Promix will be continued to foam further pipe variants, throughputs, and other polymers with this technology. Furthermore, they are working together on a solution for physically foamed PVC extrudates. Plastic pipes for protecting cables in the ground are available in a wide variety of diameters and wall thicknesses. One thing is the same in all cases: the cables inside the pipe are to be protected from environmental in fl uences and damage. To ensure this, appropriate standards must be met that clearly specify the properties of the conduit. Among other things, these standards specify the diameter/wall thickness ratio, which fi xes the amount of material per runningmeter of pipe. To save costs, recyclates or B-goods are often used, whose property pro fi le and processing characteristics are highly dependent on the batch PROMIX Solutions AG www.promix-solutions.com CO 2 Reduction and Cost Savings Through Physically Foamed Cable Protection Tubes Saving costs by using environmentally friendly gases Another approach to reducing costs and plastic con- sumption is to physically foam the pipes. Here, envi- ronmentally friendly gases such as carbon dioxide or nitrogen are injected into the plastic and mixed with it in the extruder. In the subsequent pipe extrusion pro- cess, these gases form a fi ne-pored foam that leads to weight reduction and thus to savings in plastic. Joint venture – working together for the best result In a joint project of the companies Hans Weber Maschinenfabrik and Promix Solutions, the feasibility, practicality and savings potential have now been de- termined. For this purpose, WEBER provided a grooved barrel extruder type NE7.40 for the foamed middle layer and a grooved barrel extruder type NE5.40 for the inner and outer layers. A WEBER PKM250 3-layer pipe head was used as the die. In addition, the downstream equip- ment available in the technical center of Hans Weber GmbH: Cooling section, haul-off and saw were used. Promix Solutions provided an N400 gas dosing station with adapted injector for precise metering of the nitro- gen and a P1 180 melt cooler for homogenization and Weber pipe extrusion line equipped with Promix physical foaming system Foamed cable protection tube is using 15 to 26% less raw material compared to conventional products. This saves costs and adds tomore sustainability