“Thermoplastic elastomers (TPE) combine the properties of vulcanized rubber with the processing properties of thermoplastics,” says Kjell Fagerström, president of ELASTO Sweden which is part of the in the Swedish HEXPOL group. “TPE is a dynamic and powerful material with many different properties. They can be soft and jelly-like, hard and rigid, transparent or coloured. We have developed them so that they can be flame-retardant, adhesive, glossy, or matte, they even have qualities with the ability to expand in water.”
“The soft grip on your toothbrush may well be made from the TPE material Dryflex ®. The same goes for the various components in your car – maybe the splashguard or the materials on the surface of the accelerator pedal. After work, you are probably concerned that the material in your sports and leisure products can withstand a beating. TPE can be stretched, compressed, bent and used indoors and outdoors in all conditions. TPE is used in everything from ski boots, grips, ski poles, golf clubs, bicycle saddles, swimming fins to children’s boots and toys.”
“One thing that TPE materials have in common is that they are completely recyclable. It is possible to process in many ways, from injection moulding to extrusion. Shorter cycle times, lower energy consumption and less waste also contributes to the environmental benefits of TPE,” continues Fagerström.
“If you become ill, you will probably encounter TPE in the form of the material Mediprene ® available in a variety of medical devices such as tubing, catheters, inhalers and more,” says Fagerström.
TPE from renewable raw materials
In many industries there is an increasing interest in using renewable materials in various applications. Cork is one such material that is probably most associated with wine bottles, building materials and shoe soles. The material is peeled from the cork oak (Quercus suber) bark when the tree is 20-25 years old. Cork oak survive and form new bark that can be harvested again after about ten years. Trees live 150-200 years and deliver an average of 16 harvests during their lifetime.
Müller Kunststoffe, which is a company with the HEXPOL TPE Group, has developed a method to combine cork with thermoplastic materials. The products are called Lifocork ® and combine the low weight, durability and feel of a natural product with the process-ability of a plastic material. Lifocork ® is manufactured by a special process developed by Müller Kunststoffe, where the cork, in a cost and energy-efficient manner, gets combined with thermoplastic materials. The method is based on technology that is common in the TPE industry, such as injection moulding and extrusion.
Lifocork ® can be used in many different products and new opportunities are opening up almost every day. The material is lightweight, provides good grip, is comfortable to touch and is therefore excellent for tool handles, sporting equipment and other household items. Lifocork ® is also used for bowls, trays, toys, flowerpots and similar applications.
In a co-extrusion method, Lifocork® can adhere to TPE, polypropylene or polyethylene. This creates opportunities for sophisticated design solutions where smooth surfaces can become part of the product. By extrusion, for example, plates, belts, tapes and profiles are manufactured from Lifocork®. Foamed Lifocork® can be used as cushioning in orthopedic shoes.
Old tires and plastic waste gets new life
The EU Directive “End of Life of Vehicles” (ELV) intends to recycle as much material as possible from end of life vehicles. The automotive industry has implemented many measures to meet these requirements and has developed certain types of TPEs as a response to the increased demand for recyclable material. The automotive industry also strives to increasingly use recycled materials in new vehicles. ELASTO UK has developed a material that contains 65 to 80 percent recycled materials from plastic and rubber waste, by weight. The material, called Dryflex ® Post Consumer Waste, consists of recycled plastic (polypropylene) and rubber granules from used tires. Recycling is positive from an environmental perspective, but beyond that the material has several advantages compared with new ingredients. This includes superior properties for UV and weather resistance and sound attenuation.
Dryflex® has been tested and approved by Land Rover Materials Engineering Laboratories. Some examples of products are mudguards, side steps, stone chip protection and front lips – components that not only last the car’s lifetime, but that also can be recycled when the car is scrapped.
Read more about TPE at: ”Tailored elastomers contribute to sustainable development”.
The article was published in March 2013