Thermoplastic polyurethane (TPU) is any of a class of polyurethane plastics with many properties, including elasticity, transparency, and resistance to oil, grease and abrasion. Technically, they are thermoplastic elastomers consisting of linear segmented block copolymers composed of hard and soft segments.
TPU is a block copolymer consisting of alternating sequences of hard and soft segments or domains formed by the reaction of (1) diisocyanates with short-chain diols (so-called chain extenders) and (2) diisocyanates with long-chain diols. By varying the ratio, structure and/or molecular weight of the reaction compounds, an enormous variety of different TPU can be produced. This allows urethane chemists to fine-tune the polymer's structure to the desired final properties of the material. For example, a greater ratio of hard to soft segments will result in a more rigid TPU, while the reverse is also true.
TPU has many applications including automotive instrument panels, caster wheels, power tools, sporting goods, medical devices, drive belts, footwear, inflatable rafts, and a variety of extruded film, sheet and profile applications.[2][3] TPU is also a popular material found in outer cases of mobile electronic devices, such as mobile phones. It is also used to make keyboard protectors for laptops.
TPU is well known for its applications in wire and cable jacketing, hose and tube, in adhesive and textile coating applications, as an impact modifier of other polymers.[5]. Also used in performance films, for example transparent TPU is used in high demanding transparent film applications like high impact resistant glass structures (TPU glass lamination Films)
TPU is the thermoplastic elastomer used in FFD fused filament deposition 3D printing. The absence of warping and the fact no primer is needed, make it ideal for filament 3D printers when objects need to be flexible and elastic. The fact that TPU is a thermoplastic allows those filaments to be melted again by the 3D printer "extrusion" head, and then cooled back into the solid-elastic piece. TPU powders are also used for other 3D printing processes, like LASER Sintering (SLS TPU) and 3D inkjet printing (TPU powder bed). It's also possible to use in big equipments vertical injection or extrusion machines to directly print, without the intermediate step of filament extrusion or powder preparation, just choosing the adequate TPU granulates (pellets).