Making the sole stick without hazardous chemicals
Surface preparation of soling materials is a critical step in shoe manufacturing. As such, it is generally done by hand resulting in a time-consuming and labour-intensive process involving the use of hazardous chemicals. Elevated labour costs have forced much manufacturing to developing countries with lower wages and often less stringent safety regulations. European researchers initiated the ‘Intelligent and multifunctional rubber compounds/adhesives for the shoe industry’ (Innorubber) project to develop better bonding technology without the use of hazardous chemicals, simultaneously reducing costs and enhancing the competitive edge of European shoe manufacturers. Following a worldwide survey of the most common bonding systems used by shoe manufacturers, scientists chose materials to evaluate for potential modifications. Their goal was to develop so-called intelligent and multifunctional materials. Intelligent materials respond to changes in their environment in ‘smart’ ways much as a living organism does. For example, a change in pressure or temperature could result in a predictable change in shape or mechanical properties. Along these lines, investigators studied the pre-activation of bonding sites that could enhance bonding without the use of chemicals and without negative effects on the finished product. Intelligent bonding materials could potentially eliminate surface treatment and thus reduce production time and labour costs. They would also enable eliminating the use of hazardous materials and thus a substantial reduction of insurance rates. Taken together, Innorubber concepts could restore the competitive edge to European shoe manufacturers while protecting worker health.
