Celanese Introduces Bio-based Elastomer for Foamed Footwear

Celanese has introduced a bio-based Hytrel TPC RS40F2 copolyester elastomer which, when foamed, is suited for athletic footwear applications. Incorporating a minimum of 20% segregated bio-content, Hytrel TPC RS40F2 is foamed using a physical supercritical fluid (SCF) process to help support the sustainable development objectives of athletic footwear brand owners and manufacturers. The bio-content is verifiable via the C14 method.

Bio-based polymer elevates energy-return performance

Pristine white foamed bio-based Hytrel TPC RS40F2 is well-suited for midsole components of athletic footwear as it delivers lightweighting opportunities while elevating energy-return performance with the rebound and resilience associated with other Hytrel TPC grades. Hytrel TPC is widely used in various industries due to its advantages in lightweighting, heat insulation, sound absorption, and shock, moisture, and corrosion resistance. Hytrel TPC RS40F2 can also be colored to meet design needs while maintaining material properties.

“This new bio-based grade is part of our expanding Hytrel TPC ECO-B portfolio,” said Peter Wing, global marketing manager of consumer products. “It offers numerous benefits for athletic footwear brand owners and manufacturers that align not only with their sustainability ambitions but also their aspirations for elevating shoe performance. We are very excited about how we can enable athletic footwear designers to redefine the category, as well as the contributions this new foamed polymer can make across the value chain."

Related:Celanese Laser-focused on Sustainability

Hytrel TPC RS40F2 midsole foamed using an autoclave blocker. Cutting position was in liquid nitrogen. A JEOL EC-30000BU auto fine coater was used with 20 mA/60S. SEM method was high vacuum, 10 KV. Image courtesy of Celanese.

Physical SCF foaming, which is leading a process technology transformation, results in a unique cell structure with elevated properties and good skin compatibility. The process itself offers environmental benefits as there are no corrosive foaming agent residues to impair mechanical properties. Additionally, it generates low odor and emissions and exhibits no toxicity.

Environmentally friendly foaming

Traditional materials for insoles and midsoles have typically relied on chemical foaming agents that can generate volatile organic compounds (VOCs), which react with sunlight to form ground-level smog. This is an environmental concern. 

Celanese is collaborating with Xingxun Enterprise, an innovative processor, to produce world-class foamed polymer applications. Experts from both companies have worked together to successfully develop the processing of Hytrel TPC RS40F2 shoe soles using physical SCF foaming technology. This new foaming polymer enables Xingxun to deliver a lower carbon footprint solution to athletic footwear brand owners.

Additional benefits include: 

“Celanese's proprietary technology allows the bio-content of many of our ECO-B materials to be tailored, and we look forward to working with customers on their specific athletic footwear applications," said Wing.