Residue
The latest tests confirm a new breakthrough in the footwear sector by closing the life cycle of the waste and bringing to the market a new product that is much more sustainable and committed to the environment
The Footwear Technology Center of La Rioja, CTCR, and the CARTIF, the Technology Center from Valladolid have successfully completed the project to produce shoe soles from recycled polyurethane foam. The objective of this research that was also promoted along with the other partners of the consortium, the Riojan companies, Garmaryga and Caucho Ruiz-Alejos have been demonstrated, showing the viability of this type of recycled plastic for a more sustainable footwear. The obtained formula uses 40% of recycled polyol, resulting in soles that meet all the technical requirements and quality standards, the same as with virgin polyol, but with the added value of being recycled.
The systematics applied to reach the final goal has been based on different chemical processes - such as glycolysis - breaking the polymer chains to return to the initial monomer, a polyol. On the basis of this and by the incorporation of other additives, a new component is added to the formula to manufacture polyurethane foams for new soles.
Comfort, resistance, lightness, impermeability, are just some of the requirements of polyurethane, playing a fundamental role in the manufacturing of safety, sports, leisure footwear, etc. But also for shoes for street use, as it is increasingly common to find it in fashion footwear, with greater design demand. And this need is covered through the research results from the CTCR and CARTIF, confirming that the results are replicable for both professional footwear and fashion footwear, regardless of their functionality.
From this point of view, it is worth highlighting that in Spain approximately 102.8 million pairs of shoes are sold annually, which means that a similar figure will end up in urban landfills. Thus, with this project, manufacturers of footwear and components could contribute to reduce the environmental impact by recycling and not using conventional materials of slow degradation.
Currently, the parties involved in the project are studying the profitability of production in order to, in the future, obtain polyol through the industrial glycolysis process. The success of the project, at a technical and environmental level, offers a new way of re-use within the footwear sector, which so far has been inexistent. Moreover, it is a novel model for implementing the circular economy in favor of optimizing resources. The collaboration of polyurethane footwear manufacturers at regional level and the conclusions of the technical-economic feasibility study will mark the new challenges in order to obtain recycled polyol in the regional production area.
From the point of view of experts:
Marta Calvo, CTCR's Director of the Quality and Environment Department: "After completing the research through the industrial tests carried out in the companies of the consortium, a viable technological solution has been obtained for the successful re-use of the waste of polyurethane, which is a leftover of the industries dedicated to the injection of soles of footwear. This is a successful and clear example of the application of circular economy in the footwear sector ".
Alicia Aguado, researcher in the Area of Environmental Technology at CARTIF: "The obtaining of an optimum polyol through the chemical recycling of polyurethane foams present in the soles of footwear, has been a great challenge with a very positive and satisfactory result. Being able to recycle and give added value to a waste that currently ends in landfill, and above all, managing to produce a product of equal standing as the initial one, managing to complete close the life cycle of these wastes is a great success”.
Recycled Polyol Recycled soles Recycled soles
