Extrusion International 6-2020

31 Extrusion International 6/2020 The requirements for thermoforming fi lms for food packaging are substan- tial: high barrier properties for a long shelf life of the packaged goods, seal- ability, printability, appealing surface properties and gloss. In addition, they should have the lowest fi lm thickness possible and possess good thermo- formability. Although cast fi lm extru- sion is an established manufacturing process for deep-draw thermoform- ing fi lms, clear advantages can be ob- tained with the Triple Bubble ® technol- ogy. Kuhne Anlagenbau has taken the fi rst step to demonstrate this through extensive tests on their 13-layer Triple Bubble ® system at their in-house R&D center. “We have succeeded in pro- ducing fi lms that, compared to 150 to 180 μ m thick cast fi lms, are only 80 μ m thick. This represents a dramatic thick- ness reduction of roughly 50%,” says Managing Director Jürgen Schiffmann, describing the fi rst big step on the path to more environmentally friendly ther- moforming fi lms. tures with EVOH and PA barrier layers. That is why Kuhne Anlagenbau has gone one step further and, together with a european fi lm manufacturer, has developed a 5-layer PP-based so- called “mono-material” fi lm. This en- vironmentally friendly fi lm consists of 95% PP with only 5% of foreign mate- rial and is therefore recyclable. The fi rst deep-drawing tests with the new, thin and recyclable fi lm at the fi lm manu- facturer were absolutely convincing. This fi lm has excellent machinability and leads to very uniform and stable packaging solutions. With these innovative fi lms, Kuhne An- lagenbaunotonlydemonstrates itsme- chanical engineering concepts, which are perfectly tailored to the market, but also its development skills. “Deep- drawing fi lms that are produced on our Triple Bubble ® lines represent a quantum leap in terms of thickness re- duction and recyclability”, summarizes Jürgen Schiffmann while inviting in- terested customers to further develop- ment cooperation and test runs in the R&D center in Sankt Augustin. Kuhne Anlagenbau GmbH Einsteinstr. 20, 53757 Sankt Augustin, Germany www.kuhne-ab.de BLOWN FILM Environmentally Friendly Deep-Drawing Films – Thin and Mono-Material Kuhne Anlagenbau GmbH, the blown fi lm system specialist from St. Augustin, Germany, has developed innovative deep- draw thermoforming fi lms for packaging food products such as bread, meat and cheese in collaboration with its customers. The highlight of these multi-layer fi lms, which are produced on Triple Bubble® blown fi lm lines, is their reduced thickness, which is up to 50% less than that of conventional cast fi lms, and their high barrier properties despite their mono-material composition. Thus, the improved property pro fi le of these fi lms offers clear advantages to comparable cast fi lms Not only does the signi fi cant reduc- tion in thickness speak in favor of these fi lms; another plus is their ideal machinability for deep draw thermo- forming. Triple Bubble ® fi lms ther- moform better than comparable cast fi lms, according to the initial feedback from customers who have already produced the fi lms for German food companies. Jürgen Schiffmann sees the reason for this in the manufactur- ing process: After the fi lm is abruptly quenched in the fi rst fi lm bubble, and thus has an extremely low degree of crystallinity, biaxial stretching takes place in the second bubble. This biaxi- al stretching improves the high barrier properties signi fi cantly. However, the relaxation and fi xation that the fi lm undergoes in the third fi lm bubble is decisive for deep-drawability. In addi- tion to the optimal deep-drawability, the fi lms score with a perfect thick- ness distribution in the fi nal packag- es. “Despite the overall reduced fi lm thickness, the corners and curves of the thermoformed packages are just as reliable as when using convention- al fi lms. However, thewall thicknesses of the packages, though signi fi cantly thinner, are more uniform,” the man- aging director emphasizes. The Triple Bubble ® fi lms for deep- drawing applications that are already in themarket are typically 9-layer struc-