Huntsman helps to create fully recyclable TPU foam

The new material has been designed as an alternative to EVA.

Chemical producer Huntsman has developed a new thermoplastic polyurethane (TPU), which is reportedly fully recyclable, ultraviolet (UV) protected and can be extruded into a film and then easily expanded into foamed sheets. The special grade of ‘IROGRAN’ TPU was developed by Huntsman in conjunction with the China-based Shincell New Material Company, which is using the material to create foam sheets that are then utilised for insole, midsole and forepart insert applications by a number of leading international brand owners.

Designed as an alternative to ethylene vinyl acetate (EVA), the new material is said to have high energy return properties and provide long-lasting cushioning performance. According to Huntsman, the TPU film can be easily expanded in a high-pressure vessel using gas-assisted technology and without the use of the additional chemicals typically needed for foaming or cross-linking. This makes the resulting expanded foam sheet, and any post-production scraps and final footwear components both light in weight and easy to later recycle.

Huntsman developed the grade of IROGRAN TPU after in-depth discussions with Shincell about how best to improve the production of expanded TPU sheets, which are growing in popularity across the footwear sector. From a manufacturing perspective, Shincell wanted a TPU grade that would increase its productivity, help to reduce waste and cut overall energy consumption. The company was looking for a material that was free from toxic or volatile chemicals and formaldehyde residues, and which could be expanded without the use of butane, fluoride and azodicarbonamide foaming agents. Additional requirements called for a comfortable, durable, long-lasting TPU system that would be suitable for use in high-performance sports footwear, would outperform EVA in terms of cushioning set properties, and be easily recyclable.

“Shincell came to us with a really clear vision and set of technical requirements,” said Yi Li, business development manager at Huntsman. “It was great to work together on this project and create such a novel material. We are sure news of its development will generate lots of interest from material specifiers in different parts of the footwear sector.”

Shincell is currently testing the new grade of IROGRAN® TPU for other consumer applications and is exploring the potential to use the material in the automotive industry. Other softer grades of the material are also expected to be in the development pipeline.

Publishing Data

This article was originally published on page 40 of the January 2022 issue of SATRA Bulletin.

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