People around the world want to make significant changes and embrace sustainability – a new mindset that also affects the fashion industry. But how can you make shoes that have been made with lots of plastic in recent decades more sustainable and eco-friendlier? Covestro is a world-leading supplier of high-quality polyurethane and teamed up with the Brazilian shoe manufacturer Calçados Beira Rio to put its best foot forward and create a solution.
In 2019, the technical teams of Beira Rio and Covestro met and decided to collaborate – it is the next logical step, considering that modern shoes are increasingly made of plastic materials. Plastics are not necessarily known to be sustainable, and one example of this is the abrasion of shoe soles: Because they're not truly recyclable, most of them end up in the trash. Fighting the odds, the new concept shoes show that a sustainable approach and a fashionable look are not mutually exclusive: "The project is an important step for the industry and us, because it shows that more sustainable solutions allow for increased design freedom and work well even in the fast-paced fashion industry by delivering the same or even a superior performance over current alternatives," says Dr. Frank Rothbarth, Trade Media Communications Manager at Covestro.
The collaboration resulted in elegant women’s pumps and comfortable casual shoes based on alternative raw materials such as plastic waste. They are put to good use in a circular economy, instead of being released into the atmosphere as waste gas. The inside lining of both shoe concepts is designed to deliver a great fit and comfortable footfall. This cushioning effect typically comes from a conventional soft foam. The concept shoes feature a new type of foam made of cardyon®, an innovative raw material that enables manufacturers to create soft footbeds. This precursor product contains up to twenty percent carbon dioxide and replaces some previously used fossil raw materials. Cardyon® makes this possible without compromising the favorable characteristics of conventionally produced foam.
Besides cardyon®, the outsoles of both shoe models contain thermoplastic polyurethane (TPU). Sixty percent of the carbon content is derived from biomass. "As a result, both products have a lower CO₂ footprint than fossil-based TPU and help close the carbon cycle," says Rothbarth. Recycled plastics also find a new useful life in the shoes. "Used polycarbonate products are shredded, cleaned, possibly mixed with new plastic and reused as recycled material," he adds. This adds lasting strength and durability to the insole and heel of the shoes.
Fashion accessory production primarily aims to benefit and please customers – also when it comes to sustainability. But Beira Rio wants to do more and strives to improve hygienic conditions in production. For its new concept shoes, the footwear manufacturer increasingly uses water-based raw materials, which emit significantly fewer volatile organic components than the solvent-based substances it used in the past. INSQIN® technology is based on water-based raw materials and was developed specifically for a more sustainable textile coating. This makes it ideal for the lining, upper material, and heel of the women's pumps. The company also used a more sustainable footwear adhesive. "Aqueous adhesives with the polyurethane dispersion Dispercoll® U provide the necessary strength in the upper and outer sole of both shoes,” explains Rothbarth.
Like all industries, the fashion sector must rethink its sustainability goals and targets. As demonstrated by Covestro, innovative ideas are a first step in the right direction. Covestro plans to take its newly acquired knowledge through its collaboration to enter new markets in the future. Says Rothbarth: "Our company wants to partner up with other clients and shoe manufacturers to create innovative concepts together, promote sustainable industry practices, and improve the value chain." Quite possibly, the concept shoes will inspire other manufacturers to follow in the company’s footsteps as they have shown that sustainability and fashion can go hand in hand.
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