Jul 2 2006
As design materials for ski boots, transparent grades of Desmopan® thermoplastic polyurethane (TPU) have set new trends and are being used by more and more manufacturers. Now, with the introduction of Desmopan® DP 9650DU, DP 9659DU, DP 9662DU and DP 9665DU, Bayer MaterialScience AG has succeeded in developing a new generation of these aromatic ether TPUs that offers even better performance. "The strength of the new grades lies in the significantly improved low-temperature flexibility and low-temperature impact strength. These features mean that ski boots can be made stronger and manufactured in thinner wall thicknesses, thus allowing greater design freedom. This is especially true for areas where two different TPU materials overlap," says Luigi Cermesoni, head of the Sports&Leisure TPU segment at Bayer MaterialScience. The new materials are already being used by well-known manufacturers such as Tecnica (in its Diablo model) and Nordica (in its Speedmachine model).
The market success of these transparent TPU grades can be traced back to the greater degree of freedom they allow in designing ski boots. For example, alternating between transparent and opaque colored areas produces varied contrasts. If decorated areas are oversprayed with transparent TPU, a 3D deep-gloss effect is produced, which makes the design stand out. The interesting and attractive technical features of a ski boot’s internal workings can be made clearly visible, allowing the manufacturer to communicate his design skills and technical expertise.
Furthermore, it was of key importance to developers at Bayer MaterialScience that the new Desmopan® grades should be efficient and cost-effective to process. As a result, compared to the first generation, these have improved free-flowing properties. This makes more complex parts geometry easier to produce and allows gentler processing at lower injection pressures. Crystallization has also been optimized. Compared to first-generation TPU grades, the melt solidifies even faster, which reduces cooling and cycle time, thus increasing productivity.
The new plasticizer-free and UV-stabilized TPU grades are available in hardnesses of 50 to 65 Shore D, enabling their use for both hard structural parts and, for example, soft shells and shafts. Desmopan® 9650DU and Desmopan® 9659DU are particularly suited to the trend for altogether softer ski boots.