Extrusion International 5-2017

21 Extrusion International 5/2017 Fig. 2: The 7 layer barrier foil which comes out of the extrusion machine runs directly into a multi cavity deep drawing and punching machine. The remaining punched frame and any bad parts produced are then fed directly into a cutting mill (in the background at the end of the machine) and fed back into the production line from there foil together with other plastics. At Greiner Packaging in Kremsmünster, Upper Austria, a 7 layer compound foil is used top produce coffee capsules. (See fact box “Multi layer foil for coffee capsules”) motan and Greiner Packaging have developed a sustainable production concept As the cups of the coffee capsules are produced from the compound foil by deep drawing and punching, more than 50 per cent of the film remains as a punched frame. As this quantity of waste could not have been disposed of logistically or economically due to the projected mass pro- duction, Greiner Packaging developed a concept for com- plete recycling of the punching waste during ongoing production together with the long term system partners, the German motan group, a manufacturer of peripheral systems, and Luger GmbH from Austria, as motan project planners and plant fitters and the extrusion technology supplier. For this purpose, the multi layer foil to be pro- duced must be adapted in such a way that up to 60 per cent of it can consist of the regrind of the original foil. The punched frame and waste parts are ejected directly from the deep-drawing machine and fed into a mill (Fig. 2). The regrind goes either into a storage silo or into BigBags and is fed from there to the extrusion plant, where it is made into a mixed polymer which provides the two main layers of the compound foil. Therefore, including the ad- dition of new material, 70 per cent of the total material throughput of the projected conveying and dosing unit is provided by the recycling circuit. The comparatively small material throughputs of the additional four extruders represent the remaining 30 per cent. These four extruders are arranged on two levels around the central “regrind extruder”, which is on the base level. It is flanked by the extruders for the central barrier layer and the adhesion promoter layers. The extruders for the two top layers are “on the first floor”. The material traps for the extruders underneath are on the second floor (Figs. 3 to 5). Compared to the complex dosing and mixing technolo- gy, the design of the pipeline system is simple and direct, with fixed piping to each material trap. There is no cou- pling station or intermediate material drying. Dosing precision lies in the detail As mentioned above, most of the material throughput is from the regrind layers, which are supplied via gravimetric dosing units and a downstreammixing system due to pos- sible fluctuations in the bulk density. Comment by Helmut Reckziegel, Head of Business Unit Capsules: “In this re- Fig. 3: A 5 aggregate extruder is used to produce the 7 layer barrier foil. The central extruder is responsible for 70 per cent of the foil in the form of the recycling percentage. It is flanked by the extruders for the barrier layer and the adhesion promoter layers. On a production level arranged above this, the extruders for the PP cover layers are arranged, which are connected to the feed block via vertical smelting lines (visible in the background) Fig. 4: The 7 layer foil machine is constructed in three functional levels on top of each other. On the lowest level (not visible here) there are three extruders (see Fig. 3), on level two there are two extruders for the cover layers, on the top level the dosing units to supply the extruders situated below