TPU — Thermoplastic Polyurethane
Thermoplastic Polyurethane
TPU (thermoplastic polyurethane) is a thermoplastic elastomer prized for its excellent abrasion resistance, flexibility and toughness. It is the reference for wear parts: seals, shoe soles, cable jacketing and protections exposed to friction.
- Mold temperature: 30-60°C
- Melt temperature: 190-230°C
- Shrinkage: 0.8-2.0%
- Density: 1.10-1.25
- Manufacturer grades: Elastollan 1185A (BASF), Desmopan 385 (Covestro), Estane 58277 (Lubrizol)
Processing
TPU is hygroscopic: drying of about 2 to 3 h at 80-110 °C is required before molding, otherwise moisture causes hydrolysis, bubbles and loss of mechanical properties. Run the melt between 190 and 230 °C with a mold regulated between 30 and 60 °C. Its softness and low viscosity demand good mold clamping to limit flash.
Advantages
- Excellent abrasion and wear resistance
- High flexibility and toughness, even at low temperature
- Good resistance to oils, greases and hydrocarbons
- Recyclable, tough elastomer for dynamic parts
Limitations
- Hygroscopic: drying at 80-110 °C required to avoid hydrolysis
- Hydrolysis-sensitive: moisture permanently degrades the material
- Moderate continuous service temperature
- Soft, low-viscosity material: prone to flash
Common injection molding defects
- Bubbles — Moisture flashing to vapor: dry TPU at 80-110 °C before molding
- Flash — Soft, low-viscosity material: lower pressure and improve mold clamping
- Weld lines — Cooled melt front: raise melt temperature and injection speed
Typical applications
Shoe soles, cables, seals, abrasion-resistant parts