Progress to Sustainability on Stylish Soles

More and more often, people are saying "yes". Yes to traveling less by car and more by train and bicycle. Yes to more enjoyment and less CO₂ emissions through regional and seasonal food. Yes to less fast fashion and more sustainable t-shirts, jeans and sneakers.

Speaking of sneakers, do sustainable casual shoes even exist? Why yes, they do exist thanks to Continental. For example, from Monaco Ducks, a shoe manufacturer based in Munich. The founders have set a goal of offering 100 percent recyclable sneakers – and therefore, they inevitably spend a lot of time researching appropriate resources, materials and sources of origin. Some components are easier to specify than others: instead of animal leather, they use natural eco-leather; instead of conventional wool, they use recycled wool from production scraps; instead of synthetic fibers, they use vegan fibers made from wood. And of course, the big goal for the soles was to use a sustainable rubber compound as well. However, this is much more complex, because the soles have particularly high requirements: They have to be sustainable, but also robust, functional and durable. And in order to find the right mixture, the two founders contacted the material experts at Continental last year to develope a rubber mix that fits the stylish Monaco Ducks sneakers perfectly. Continental compound developer Michael Schwegmann reveals the details.

Sustainable shoe soles – no problem with the right know-how

Even if high fashion is not usually home turf for Michael Schwegmann and the Continental development team. They know just about everything about suitable rubber compounds. No wonder, because Continental has been gaining the necessary expertise for industrial material applications for over 150 years. Nevertheless, he and his team were able to apply their decades of experience to develop a sustainable rubber compound for the Monaco Ducks sneaker sole. "In our everyday development work, sustainable and CO₂-reduced materials, the guarantee of origin of raw materials and transparent supply chains play a prominent role," says Michael Schwegmann. "That's why the sustainable Monaco Ducks casual shoes also fit perfectly with Continental´s Sustainability Ambition of being climate neutral along the entire value chain by 2050 at the latest."

Reaching a smaller carbon footprint with trainers

Conventional sneakers still have a lot of room for improvement, especially when it comes to the soles. For one thing, it is virtually impossible to recycle the soles or even the entire shoe, because they consist of up to 30 different components that are firmly glued together. For another, their CO₂ footprint in production is quite high. But it is precisely in these areas that the use of innovative materials and new formulations are targeted. "The rubber compound for the sole of the Monaco Ducks sneaker is made from 90 percent sustainable raw materials," explains Michael Schwegmann. "This means the carbon footprint is 50 percent smaller compared to the original recipe.*" And what does this optimized mix look like? "For example, we use renewable natural rubber instead of synthetically produced rubber, bio-based instead of mineral oil-based softeners and silica from rice husk ash instead of synthetically produced silica," Michael Schwegmann explains.

The sustainable mix is key

More sustainability in rubber compounds is the premise which has been in place at Continental for a long time. Michael Schwegmann explains: "For several years now, we have been reviewing the lists of ingredients for our formulations, more than 2,000 and looking for alternatives that are as sustainable and environmentally compatible as possible." Together with the customers, the mixtures are then continuously developed further so that they continue to meet the high demands of the respective application on the material, even with changed raw materials. In this way, customers can also reduce their emissions, improve their CO₂ balance and become more sustainable. "And if the result is a stylish product like Monaco Ducks, that's just great.