Safety shoes are usually worn all day and every day. A common aspect of the safety shoe across models is the toe cap – that protective area at the front of a shoe made from metal or plastic to protect the toes. Usually, safety shoes are made using decades-old technology, which gives that recognizable clunky look. Even worse, they are often heavy and not particularly comfortable.
This was the focus for BIG, a company founded in 1983. ”We wanted to bring innovation to the safety shoe market“, says product developer Lothar Merk. ”Shouldn‘t shoes that protect us at work also provide optimum support for our feet and be comfortable?“ he adds to explain BIG’s fundamental aim. His colleague Magnus Kirschstein, head of marketing, adds, ”and beyond function, shouldn’t these shoes also be fashionable and reflect the individual style of the wearer?“ For safety shoes, this combination is not easy, and Merk, Kirschstein, and their colleagues are always on the lookout for the latest technologies and design ideas that they can integrate into Runnex safety shoes – BIG‘s brand name.
Merk stumbled across a promising new technology in early 2020. He wanted to use a lightweight, cushioning foam in the latest line of safety footwear to protect workers from daily wear and tear on their joints as much as athletes. ”Look at the factories! Workers need to walk miles, stand all day, climb scaffolding, and, and, and. They are athletes that perform at peak-level every day. But this performance isn’t done in sport shoes, they wear heavy safety shoes“, he explains. ”Shoes with cushioning foams provide an additional function. They provide support and comfort to the wearer by returning the impact energy normally absorbed by the shoe back to the wearer.“
Merk, a passionate recreational athlete, found what he was looking for while reading a magazine for runners. The magazine had published an overview of companies that produce materials for soles in sports shoes. Evonik was among them. The specialty chemicals company has been developing plastics for athletic shoes for about 50 years, always in close cooperation with customers and in tune with the latest trends and requirements of the sports industry. Without any prior knowledge of Evonik or having any contacts, Merk had to take a rather simple approach: ”I sent an email to info@evonik.com and that‘s how this partnership started!“
The product Merk was interested in comes from the Vestamid PEBA family. Polyether block amides, introduced to the market by Evonik more than 40 years ago, are characterized by excellent elasticity and good recovery behaviour. These are properties that leading sporting goods manufacturers value in sports shoes. They use them to manufacture midsoles, ski boot sleeves, heel parts, in other words, compact shoe components.
But now Evonik has equipped some types of material so that they can be foamed. A processor uses them to produce foam sheets of varying thickness and elasticity. The finished foam is light, durable, and resilient: Its rebound behaviour far exceeds the other soft foams previously used in shoes and it returns most of the absorbed energy back to the wearer. What’s more, its low weight ensures maximum comfort for the wearer.
That was exactly the performance profile Merk was looking for.
Kathrin Salwiczek is responsible for the material for flexible foams in the sports and leisure market at Evonik‘s high performance polymers business unit. She said: ”Our experience is based in using flexible foams made from Vestamid PEBA in sports shoes through our joint developments with customers. Adapting it for safety footwear was an exciting project. We were even able to exceed BIG‘s expectations for rebound resilience.“
The high performance of the plastic is due to the polyether segments in the polymer chain, which provide the high elasticity and good resilience. The activeBumper made from this foam provides a cushioning layer that remains elastic over lifespan of the safety shoe with no signs of material fatigue. The rebound effect, that is, the rebound elasticity of the foam, is 73%. That is said to be significantly higher than comparable products and ensures fatigue-free and joint-friendly work, all while increasing comfort.
Another property of PEBA foam is its low weight. It is up to 50% lighter than comparable expanded thermoplastic polyurethane (ETPU) foams. High resilience combined with the lower weight make every step noticeably easier, Evonik concludes.
