What TPR is
In footwear, TPR usually means a compound based on styrene block copolymers, most often SBS (styrene-butadiene-styrene), sometimes SEBS. These polymers have hard polystyrene end blocks and a soft rubbery middle block. At room temperature the hard blocks hold the material together like cross-links; when heated, they soften and the material flows. Compounds add oils, fillers such as calcium carbonate, and other polymers to set hardness, feel and cost.
How TPR outsoles are made
- Compounding — Polymer, oil, fillers and pigments are mixed and pelletised.
- Injection molding — Pellets are melted and injected into a cooled mold, either as a separate sole or directly onto the upper.
- Cooling and ejection — The part solidifies within seconds and is ejected, ready to use.
No vulcanization step is needed, which shortens cycle times and reduces energy use.
Runners and rejects can be reground and reused in production.
Grip: 4 / 8, Medium
TPR gives adequate traction on dry, everyday surfaces, but it usually grips less than vulcanized rubber, especially on wet, smooth floors. Softer, oil-extended grades improve grip somewhat, at the cost of wear. For footwear where slip resistance is critical, rubber is the safer choice.
Flex: 6 / 8, High
TPR is rubbery and bends well, so soles feel flexible and comfortable out of the box. Its main limitation is temperature: TPR softens as it warms and becomes stiffer in the cold, so flex and feel change more with the weather than a vulcanized rubber sole's would.
Abrasion: 4 / 8, Medium
Without chemical cross-links, TPR wears faster than vulcanized rubber, with higher volume loss in ISO 4649 testing. It can also deform or scuff from friction heat during hard use, such as dragging feet or braking. For everyday casual wear it lasts reasonably well; for high-mileage or heavy-duty use it does not.
Where TPR is used
- Casual and fashion footwear — sneakers, loafers and boots at accessible price points.
- Children's shoes — light, flexible, colorful soles for shoes that are outgrown quickly.
- Slippers and house shoes — soft, quiet soles for indoor use.
- Unit soles for high-volume production — fast, low-cost injection with consistent quality.
Designing with TPR
Choose TPR when cost, color freedom and fast production lead the brief and the shoe will not face heavy wear or critical slip risk. Choose vulcanized rubber when grip or longevity are part of the product promise.
- Use deeper, more open tread patterns to compensate for lower wet grip.
- Avoid TPR in hot-climate or high-friction uses where softening is a risk.
- Specify SEBS-based grades when UV and heat stability matter.
- Consider a rubber insert in the heel or forefoot to extend wear life.