Eco-friendly torsion plates
In the same way that Formula 1 racing cars serve as test beds for new automotive materials and technologies, so the sports shoe sector of the footwear industry has been instrumental in formulating new concepts in footwear design and construction.
Foremost among these has been the way outsoles and mid soles are constructed in order to cushion the foot on impact when running, which has led to a greater emphasis on the general aspects of comfort in everyday footwear. The popularity of athliesure footwear with its close links to sports shoes is plain to see everywhere and this must be to a large degree due to the comfort factor.
A more recent sports shoe development has been the introduction of carbon fibre torsion plates and bars into mid soles in order to increase lift off of the foot from the ground. This has proved to be so effective in improving an athlete’s running action that it is now widely used by all the major sports shoe brands. Doubtless it will eventually find its way into other types of footwear in the same way that cushion mid soles have done. Needless to say, it has also led to manufacturers trying out new ways to make these plates and bars in order to stay one jump ahead of the competition. The latest innovation has come from Coats Group in the form of Lattice Lite Eco.
Coats is a well known name in the footwear industry as a major supplier of sewing threads for shoe uppers. It is in fact the world’s largest producer of industrial sewing threads, with a history stretching back to the early 1760s. Over the years, its range of footwear products and materials has diversified to also include zippers, hook and loop fastenings and trims. It also supplies advanced materials to other industries and it is from this source that Lattice Lite Eco has emerged. This is a revolutionary fibre-laying technology that uses sustainable materials to create composite materials for high performance torsion plates that can be produced to individual manufacturers’ requirements.
The company says the technology employed enables yarns to be precisely positioned in the required place and in any direction so that the thickness, torsion, flexibility or rigidity of each section of a footplate can be specifically created to ensure they support every part of the foot. It also says that this helps address the constant challenge for developers of footwear to combine high performance with comfort. The lattice that is formed by this process is then pressed and moulded into the final footplate. This would appear to be a positive development as torsion plates cannot normally be individually tailored in this sort of way. How this all comes together is illustrated in Figure 1.
Furthermore, the company says that this also eliminates the need for additional resin steps such as prepeg (composite material made from ‘pre-impregnated’ fibres and a partially cured polymer matrix) or resin transfer moulding (closed-mould process for manufacturing high performance composite components in medium volumes), which speeds up the manufacturing process to around 120 seconds and reduces material waste down to 5% from over 30% for more traditional composite operations. It can use a range of eco-friendly materials including recycled carbon, recycled nylon or materials from natural resources such as basalt and flax.
The technology has been developed in the Coats EMEA Innovation Hub based in Bursa, Turkey, where Coats collaborates with business partners, brands, suppliers, universities and start-ups to develop pioneering new products. As well as footplates, the process can also be used in toe caps, torsion bars and heel counters to create components that are both lightweight and robust. Adrian Elliot, President, Apparel and Footwear Coats, says: “Coats Lattice Lite Eco technology is revolutionary and eco-friendly. It enhances performance on multiple levels: the consumer wearing the end product and our customer who is able to create components faster, optimise manufacturing and reduce waste.”
It never ceases to amaze what natural and/or recycled materials can now be used to produce high-tech and high performance products. As Figure 1 reveals, Lattice Lite Eco incorporates no less than five such materials: flax fibre, recycled carbon or basalt and recycled nylon or PA11 (high-performance plastic polyamide made from 100% renewable castor beans). Innovations such as this can only encourage us to hope that ever more footwear applications that are renewable and use recycled materials as the cost of using fossil fuels becomes ever more expensive and controversial.
Reels of Synergex fibre and moulded Lattice Lite torsion plates.
All Credits: Coats Group
