Thermoplastic Polyurethane (TPU)-also known as thermoplastic polyurethane elastomer-is a linear block copolymer produced through the extrusion and compounding of diphenylmethane diisocyanate (MDI), oligomeric polyols, and 1,4-butanediol. Its molecular chains consist of alternating soft segments (formed by polyester or polyether polyols) and hard segments (formed by diisocyanates and chain extenders), which establish a reversible physical cross-linking network via hydrogen bonding. Manufacturing processes include the twin-screw continuous method (accounting for 78% of production) and the conveyor-bed continuous method; reaction temperatures typically range from 140°C to 250°C, and molding techniques encompass extrusion, injection molding, and others.
This material combines the elasticity of rubber with the processability of plastics. It features a Shore hardness range of 60A to 80D, a tensile strength of 20–60 MPa, and an elongation at break of 400–800%. Furthermore, it exhibits excellent oil resistance (with a volume expansion rate of less than 5%) and hydrolysis resistance (retaining over 85% of its original strength). Specifically, polyester-based TPU excels in heat and abrasion resistance, while polyether-based TPU offers superior hydrolysis resistance. Products made from this material are widely utilized in automotive seals (exhibiting a compression set of less than 30%), wire and cable sheathing, medical catheters (certified under ISO 10993), mobile phone cases, and school uniform fabrics. Notably, the TPU film incorporated into the 2025 winter uniforms for the Third Primary School of Jinshan in Inner Mongolia has been tested and verified to comply with the GB/T 31888-2015 standard. Eco-friendly TPU variants incorporate bio-based polyols at a substitution rate of 30%–45%, thereby reducing carbon emissions by 22%–35%; bio-based TPU mobile phone cases manufactured by enterprises in the Shenzhen region alone account for half of the country's total annual shipments.