Bayer MaterialScience: New thermoplastic polyurethanes for laser sintering

July 2012 – Bayer MaterialScience and Solid Composites GmbH are partnering to develop thermoplastic polyurethane (TPU) powders for selective laser sintering. This innovative method for fabricating three-dimensional structures is based on the use of a laser beam to sinter powdered starting materials. The start-up company based in Voerde, on the Lower Rhine, will be awarded a brand license to market the new high-tech materials under the name Desmosint. This opens the door to numerous potential applications, for instance in the automotive industry, in sports goods, robotics or aerospace engineering. Solid Composites is a spin-off of the Fraunhofer Institute for Environmental, Safety and Energy Technology (UMSICHT).

“Solid Composites has made a name for itself as a creative developer and supplier of thermoplastic powders for laser sintering and electrostatic coating, among other things, and is therefore the partner of choice for us when it comes to successfully marketing our TPU innovation,” explains Jürgen Hättig, TPU marketing specialist at Bayer MaterialScience.

No molds necessary
Selective laser sintering is becoming a firmly established digital manufacturing method in the additive manufacturing of plastic parts. A part is made from a thermoplastic powder based on the part’s structural design data. Guided by CAD software, a laser fuses successive layers of a powder bed at selected points where the part is to emerge. In other words, the part “grows” layer by layer. “The method eliminates the use of molds, and that cuts costs considerably. Furthermore, in contrast to injection molding, even parts having complex geometries with cavities and undercuts can be rendered,” explains Marcus Rechberger, general manager of Solid Composites.

Material gap closed
Until now, primarily soft, elastic materials and rigid thermoplastics, such as polyamide, were commercially available for selective laser sintering. “Our TPU products, with their high toughness, elasticity and strength, have now closed the gap between these material classes. And that opens the door to good application opportunities,” Hättig says. The first representative of the new class of TPUs is Desmosint X 92 A-1. One of its advantages is that the space in which the TPU is processed layer by layer must be maintained at a temperature of only 80 °C, in contrast to polyamide, for instance, which is processed at slightly below its melting temperature. “Because heating the processing space generates most of the total energy cost, this method results in significant savings on energy. And our TPU has only a very low tendency to warp, meaning the sintering process runs very stably. Lastly, the non-sintered powder does not age inside the processing space and therefore can be used for the next job, an enormous cost advantage compared to the classical laser sintering material PA12,” Hättig explains.

Potential use even in high-volume production
Selective laser sintering typically offers great design freedom and is particularly suited to the additive manufacturing of short to extremely short runs, for instance in the production of components like housing parts, bellows and hoses for full-size and luxury sedans. When used with the TPU products, the method also is ideal for producing custom components, such as orthopedic shoe inlays, athletic shoes, helmets and prosthetic devices. “Beyond that, the technology may prove suitable in high-volume production, too, particularly in those cases where part geometries are very intricate and the cost of injection molds high. In these scenarios, the use of several sintering machines can be more cost efficient,” Rechberger explains. At the end of the part’s service life, the plastic is fully recyclable.

About Bayer MaterialScience:
With 2011 sales of EUR 10.8 billion, Bayer MaterialScience is among the world’s largest polymer companies. Business activities are focused on the manufacture of high-tech polymer materials and the development of innovative solutions for products used in many areas of daily life. The main segments served are the automotive, electrical and electronics, construction and the sports and leisure industries. At the end of 2011, Bayer MaterialScience had 30 production sites and employed approximately 14,800 people around the globe. Bayer MaterialScience is a Bayer Group company.

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Find more information at www.materialscience.bayer.com and www.solidcomposites.de.

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