There are several different kind of TPEs, thermoplastic elastomers, also known as TPR, thermoplastic rubber. The most common in outsole production is SBS, Styrene-butadiene-styrene, SEBS, Styrene-Ethylene/Butylene-Styrene and TPU, thermoplastic polyurethan. Normally when TPR is mentioned it refers to SBS. TPU is widely known under it´s correct name. EVA is also a thermoplastic elastomer but is handled in a separate article.

TPR

TPR, Thermoplastic rubber, or SBS, Styrene-butadiene-styrene, is a widely used material for outsole production.

  • Rubber look and feel
  • Relatively light
  • Good cold resistance
  • Low cost

Unit TPR outsole

TPU

TPU, Thermoplastic polyurethane, has similar use cases as TPR but has specific applications where it´s preferred though a higher price level. The advantages of TPU compared to TPR

  • Transparency level
  • Soft/elastic handfeel
  • Heat resistance
  • Oil/Chemical resistance

TPU outosle with welt and heel attached

Injection molding

This method is used to manufacture outsoles which later on will be assembled to the upper of the shoe. The same machinery can be used for both PVC and TPR without any considerable modifications. Read here on how the injection molding process works.

Injection molding for TPR and PVC

Direct Injection Process (DIP)

Unlike TPR, TPU can be used in the DIP process. Generally the same machinery can be used for both PVC and TPU without any considerable modifications. This process is used to directly mold and attach an outsole in one step. Read here on how the direct injection process works.

Direct Injection Process with machine workable with both TPU and PU

References

https://en.wikipedia.org/wiki/Thermoplastic_polyurethane

http://www.sespoly.com/products/tpr-thermoplastic-rubber/

https://www.morevafoam.com/knowledge-base/shoes-sole-classification-and-characteristics

https://howtoshoes.blogspot.se/2014/05/basic-of-shoes-bottom-parts.html

http://read.nxtbook.com/wiley/plasticsengineering/april2016/consultantscorner.html