New cushioning for shoe insoles developed with Vistamaxx PBE

Germany-based nora systems has developed a range of certified shoe components including shoe insole material.

Typical applications include artificial forefoot cushioning, soft sockets for people who have foot stumps, and diabetes-adapted foot bedding. They all need soft, resilient materials that provide additional relief for the foot or an ultra-soft top layer.

The key advantages of Vistamaxx PBE in Astro form 8 include excellent cushioning and damping performance; thermoforming for simple insole manufacturing; and new possibilities in automotive, furniture, medical engineering and sport .

Trends for softness and resilience

Because of medical conditions like diabetes or inflammation, orthopaedic shoemakers make custom insoles for people whose feet need specialised support. One of the most important properties of materials used in this application is cushioning. The ideal material is durable enough for everyday use, but pliable enough to offer sufficient comfort.

Insoles are traditionally made from closed-cell EVA foams. With an increasing need to add softness and flexibility to insoles, nora systems has developed a new material with improved properties compared to harder EVA-based foam.

Astro form 8, which is based on ExxonMobil Chemical’s Vistamaxx PBE, is a closed-cell foam offering a number of advantages versus EVA-based foam.

With a hardness of 8 Shore A, Astro form 8 is softer than EVA-based foam and it is durable and flexible. It also delivers good touch and haptic properties.

The material has excellent recovery capability, returning to its original shape after compression. It has also been skin tolerability tested and certified by the Fresenius Institute.

Processing benefits

Compared to SBS-based Astro med 10, Astro form 8 can also be thermoformed, making it easier for insole manufacturers to produce a custom-made insole and helping to speed up production.

“By using Vistamaxx PBE we created an even softer product, 8 Shore A versus 10 Shore A, reaching regions where we almost get below the applicability of the Shore A scale, while still maintaining excellent recovery and thermofomability,” says Dr Mario Kröger, head of product development, nora systems GmbH.

Due to the inherent adhesion of Vistamaxx PBE, Astro form 8 also has excellent bonding properties. This is an important benefit as insoles consist of several layers which are combined in a series of manufacturing steps. Target applications for Astro form 8 include:

  • cushioning layer for diabetes-adapted footbed (see picture)
  • cushioning in orthotics and prosthetics (such as forefoot replacement)
  • heel and forefoot cushioning
  • heel spur cavities for heel spur inserts
  • upper cushioning, such as for peroneal or ankle caps

Looking to the future

Orthotics and prosthetics will continue to be a primary business for nora systems, but it recognises the advantages of this new material and is keen to move into other markets.

“Right now Astro form 8 is used in orthopaedics but we are aiming for new applications which require excellent surface properties and very soft touch,” says Jürgen Schmitt, headof development for foams and thermoplastics, nora systems.

“A first example is bumper parts for cleaning robots which is in the test phase.”

Other markets that could potentially use the new material include sporting goods, furniture, medical engineering and automotive.


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