In response to the growing concerns, the environmental impact has become a key strategic driver for Decathlon's performance in the past few years. The target of reducing by 20% the absolute CO2 emissions from 2021 to 2026, to reach 9,2 million tons CO2 eq. in 2026, has been fixed. Since the products manufacturing account for 80% of the Decathlon CO2 emissions, reviewing all the industrial processes to make them less impactful is now mandatory.

The footwear industry is no exception to that, and with all the processes needed to make a shoe (upper assembly and functionalization, sole injection and foaming, shoe assembly), the labor intensiveness and environmental impact are quite important. Moreover, Asian countries have taken 87,4 % of the manufacturing world share (2023 World Footwear Yearbook), thus rendering the Decathlon’s 80 million pairs of shoes production (2023) highly dependent on them and their inherent energetic mix and supply lead time.

During the past few years, a new process has emerged in the footwear industry to foam the soles, the supercritical fluid (SCF) injection foaming technology. Coming from the basic principle of mixing a gas and a melted polymer resin above a given pressure and temperature, the foam component is formed through a rapid depressurization allowing nucleation and cell growth within a molded material.

Herein, the reasons why the SCF injection process will change the footwear manufacturing industry will be presented. Moreover, the current faced challenges will be reviewed. All of that will be pictured with concrete examples of product development, going into technical detail about the key process parameters and the different thermoplastic elastomer (TPE) families.