Patent Title: USE OF THERMOPLASTIC POLYURETHANE POWDERS

 Number/Link: WO2015/197515 (German)

Applicant/Assignee: Covestro

Publication date: 30-12-2015

“Gist”: TPU with very specific melt properties can be used for selective laser sintering

Why it is interesting: Additive manufacturing and “3D printing” using TPU is not new and has been mentioned before in this blog, e.g. the use of TPU in for fused deposition modelling. Fused deposition modelling is a technique where molten thermoplastics are extruded. In powder-based techniques on the other hand, thin layers of thermoplastic powder are selectively ‘sintered’ together using lasers or IR beams.  Powder techniques like laser sintering are said to have economic advantages and allow for the production more complex shapes, but suffer from low mechanical properties and brittleness. According to this application, TPU powders with specific hardness and melt characteristics (as outlined in claim 1) allow for laser-sintered objects with improved mechanical properties. In the examples a TPU is prepared from a butanediol-adipic acid polyester diol, butanediol chain extender and 4,4’MDI.  The TPU, together with some ‘fumed’ silica flow-improvement additive, is then cryogenically grinded to an average particle size of less than 150 micron and subsequently used for laser sintering.

Tetrahedron made by SLS (© Wikimedia)