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BASF puts a spring in every step - more comfort is impossible in safety footwear!

The launch of Infinergy by BASF was the debut of the world’s first expanded thermoplastic polyurethane (E-TPU). Among others, it is being used in Adidas’ “Energy Boost” running shoes. Stitchkraft is the only distributor that offers safety boots and shoes with this technology (WELLMAXX) in Australia.  
BASF’s Infinergy closed-cell particle foam is said to show good resilience, high durability and abrasion and chemical resistance.
The latest addition to the BASF foam plastics family combined the company’s technological expertise in particle foams with its experience with thermoplastic polyurethanes. The result is the world’s first expanded thermoplastic polyurethane (E-TPU), which BASF is now marketing under the name Infinergy. Our supplier Elten baptised this revolutionary innovation WELLMAXX. The German safety footwear specialist developed the implementation of the sole in partnership with BASF and the first badge of safety shoes and boots went to market in 2017. 


Safety Footwear Out Of The Rocket Science Lab

Infinergy began with BASF’s existing Elastollan TPU, which was expanded at the company’s Ludwigshafen (Germany) headquarters, using a novel procedure. The process retains the benefits of TPU and adds the typical properties of foams. As a particle foam, Infinergy has a low bulk weight, with a density of approximately 110kg/m3, and a moulded part weight of between 200 and 320kg/m3 after processing on standard moulding machines. That places the new foam somewhere between expanded polystyrene (EPS) or polypropylene (EPP), which are generally lighter, and the heavier elastomeric PU foams.
In addition, the closed-cell structure means that Infinergy absorbs little water; less than 2% by volume in 24h. Moreover, t also possesses high breaking elongation (100 – 150%, depending on density), tensile strength (approximately 600kPa) and abrasion resistance, along with good chemical resistance.

The Safety Boot That Bounces Back!

Infinergy’s good recovery behaviour is due in part to the foam’s closed-cell structure. BASF says that it is the most elastic particle foam currently available. Tests under ISO 8307 (ball rebound test) and under DIN 53512 (using a pre-set pendulum hammer) show that the rebound height for E-TPU can be as much as 55%, which is significantly higher than other particle foams like EPS (less than 20%) and EPP (30%).

Under continuous load, Infinergy demonstrated retained resilience in a high-frequency fatigue test using dynamic loads at 5 cycles per second and a constant pressure of 250kPa. After 40,000 load cycles, the thickness of the test piece of E-TPU was approximately 37mm (starting figure: 40mm). The comparator expanded polyethylene (EPE) sample remained permanently compressed and the thickness of the test piece was reduced to about 9mm. This means that our safety boots & shoes fitted with the WELLMAXX sole return almost all the energy that is applied to it back in your step. The material remains highly elastic and soft over a wide temperature range. Dynamic mechanical analysis found that it remained soft, pliable and stretchy at temperatures of minus 20°C which we hardly get to in Australia. 


Where WELLMAXX Can Help Your Sore Feet

Infinergy can be used in any applications requiring a combination of low weight, high durability and good mechanical properties across a wide temperature range for indoor and outdoor safety footwear (leather & synthetic upper). It reaches its full potential on hard floors such as concrete, tiles or compressed soil. 


Boosting The Energy And Comfort Of Safety Footwear 

Our clients constantly talk of the need for “good cushioning”. In safety footwear as well as in running shoes, this is the function of the midsole: in just a few milliseconds, it absorbs the kinetic energy generated by the runner as the foot lands and returns some of it while the foot is pressed down. High elasticity and deformability in the material used will increase the efficiency of this process. In the past, runners had to choose between hard, elastic competition shoes or very soft training shoes with a lot of cushioning. 
During the testing phase, the forces and deformation that occur during running were simulated in order to calculate the wear and the energy return. The shoes were tested across a temperature range from -20 to +40°C. Tests in the biomechanics laboratory examined the stability of the footwear and the effect of the products under different environments. Compared with ethylene-vinyl acetate (EVA), WELLMAXX is said to show three times better temperature resistance in its deformation behaviour; less hardening in the cold and less softening at high temperatures. Its durability under cyclical dynamic loading is also said to be significantly better than established EVA cushioning systems.


Award Winning Safety Footwear 

WELLMAXX was probably one of the most successful market launches for safety boots and safety shoes (To mention the MADDOX at the forefront…) in recent years. As a result, Elten has been recognized by Plus X Award as the best & the most innovative safety footwear brand - three years running and still bouncing back!

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