Huntsman and Shincell Develop Recyclable TPU Foam

Huntsman has developed a new thermoplastic polyurethane (TPU) that is fully recyclable, UV-protected, can be extruded into a film and subsequently expanded easily into foamed layers. This special class of IROGRAN® TPU was developed by Huntsman in collaboration with Shincell New Material Company Ltd., and the material is now being used by some of the world's leading footwear brands to produce foam sheets for insole, midsole and forepart applications. Designed as an alternative to EVA, the new material has high energy return properties and provides long-lasting cushioning performance. The TPU film can be easily expanded in a high-pressure vessel using gas-injection technology and without the addition of extra chemicals typically required for foaming or cross-linking. This renders the resulting expanded foam sheet and post-production waste as well as final shoe components super-lightweight and easy to recycle. Huntsman developed the IROGRAN® TPU class with Shincell following in-depth discussions about how to best improve production of expanded TPU sheets, which are gaining popularity in the footwear sector. During a technical briefing, Shincell outlined several objectives. From a production standpoint, Shincell wanted a TPU grade that would increase productivity, reduce waste and lower overall energy consumption. Shincell wanted to specify a TPU free of toxic or volatile chemicals and formaldehyde residues; and expandable without the use of butane, fluorine and azodicarbonamide blowing agents. On the performance side, Shincell was looking for a TPU system suitable for use in high-performance sports shoes, outperforming EVA in terms of cushioning set properties, and recyclable, comfortable, durable and long-lasting. Dr Xiulei Jiang, founder of Shincell, stated: "As a business, we have focused on providing our customers with clean, environmentally friendly, high-performance, lightweight materials. When we decided to find a partner to help us improve the sustainability of our foam sheets, I knew the company to talk to was Huntsman. My relationship with Huntsman predates the creation of Shincell. Huntsman has consistently provided me with high-level support, and I knew that our strong working relationship and shared core values would bring this project to life quickly and efficiently. As always, Huntsman did not disappoint. The team delivered a very special product that met all our requirements. We see numerous new applications for this versatile, recyclable material both within shoes and beyond." For shoe applications, Shincell produces expanded foam sheets that its customers then cut to the shapes and sizes they require. Since this special class of IROGRAN® TPU is recyclable, Shincell can collect any excess or scrap material from customers for reuse. After collection, the waste is ground and reformulated. It can also be sold to other customers. Yi Li, Business Development Manager at Huntsman, stated: "Shincell came to us with a really clear vision and a set of technical requirements. It has been wonderful to work together on this project and to create such a unique material. Being expandable without the use of chemicals and easily recyclable is a game changer. We are confident that news of its development will generate considerable interest from material specifiers in different segments of the footwear sector." Shincell is currently testing the new IROGRAN® TPU class for other consumer applications and is investigating the potential of using the material in the automotive industry. Softer grades of the material are also in development.