DuPont in Germany has announced the launch of Surlyn, a highly transparent packaging polymer that provides a skin film to enable automated assembly of scratch-susceptible, three-dimensional components.
The result of a three-way collaboration between machinery producer Zappe Verpackungsmaschinen (Witten, Germany), the film producer jura-plast (Reichenschwand, Germany) and DuPont, Surlyn is said to provide savings in energy, materials and time.
Germany-based household appliance manufacturer Miele is already using the new Surlyn film to prevent high-gloss, thermoplastic bezels for washing machines from becoming scratched as they make their way through the fully automated assembly line to retail and, ultimately, to the end-user’s home. The tailored skin packaging process thus helps prevent rejects and the corresponding waste of raw material.
Beyond this, the use of Surlyn allows for significant savings in terms of energy and raw material in the skin film process when compared to converting polyethylene, which was the material used in an early development stage. The skin film itself, and its production residue, can be recycled in the PE waste stream.
Jürgen Müller, managing director of jura-plast, said: "The development of this film has resolved two issues: the special formulation of the base layer made from Surlyn ensures that there is no formation of air bubbles between the component surface and the film, which would otherwise spoil the high quality appearance of the bezel.
“Moreover, thanks to its combination with a modified adhesive resin from DuPont, adhesion between the component and the film is sufficiently high for the fully assembled washing machine door, weighing around 5kg, to be transported using vacuum grippers. Yet the consumer is still able to easily peel off the film without leaving any residue behind.”
Müller added that “substantial optical, mechanical and economic benefits” are gained thanks to the Surlyn based film weighing about one third less than an alternative polyethylene film.
Surlyn’s excellent thermoforming properties are of great advantage to the machinery producer. At Zappe, MD Ulrich Zappe explained: “Thanks to its chemical structure, Surlyn remains very melt-stable and tough even when heated. This is particularly important for three-dimensional components, as it enables very high draw ratios without the risk of the film tearing at the edges.
“Moreover, thanks to the good heat absorption of Surlyn, the film becomes stretchable after only 10 seconds of heating, compared to about 15 seconds required for polyethylene, when working with our SKVA-5050 3D skin-packaging machine.
“This means that we can save a reasonable amount of process energy and on top of that achieve very short cycle times.”
Zappe added: “This time-, material- and energy-saving technology is highly suitable for the protection of almost all three-dimensional moulded parts with susceptible surfaces – regardless of the substrate material.”
