Silicone rubber is cured quickly by UV light
M omentive Performance Materials has launched a new platform of elastomer products that can be cured by simple exposure to UV light.
This UV-sensitive, platinum-catalysed system also enables curing to be accomplished at room temperature. Part geometries commonly produced by extrusion processing can be cured within significantly reduced times compared with conventional silicone elastomers.
UV-cure technology can help save energy and increase extrusion speeds while maintaining the physical properties of silicone elastomers. The UV exposure time for the curing process can be as short as 0.5 seconds, depending on the speed of the line and UV intensity. As the cure is initiated through UV radiation, the speed of cure is independent of the diameter and the cross-section of the extruded tube or profile. This enables high-speed extrusion to be carried out without the risk of under-curing.
Since curing occurs at room temperature, this new technology also has the potential for co-extrusion of silicones with temperature sensitive materials, such as polyolefins and thermoplastic elastomers.
'UV curing systems have been used in several industries for a number of years,' commented Holger Albrecht, Global Marketing Manager, Momentive.
'Now, for silicone extrusion we have developed a unique product and patented process technology. Together with our industry partners, we have introduced a new approach that does not require long heating tunnels. A small UV unit is sufficient for a high output in a small space. Based on this technology, the development of complex profiles and co-extrusion parts is now possible.' Federico Lo Cicero, President, POSA Spa, added: 'We at POSA have a history of innovation in silicone extrusion technology. These new Momentive materials will help us optimise our processing capabilities, and enable us to offer our customers a new range of compounds and re-engineered solutions.' Benchmark-supported test runs have shown that the new materials typically cure at a much higher speed for the equivalent mechanical properties, resistance to heat and other characteristics normally achieved with the traditional thermal systems. In addition, the UV system offers the processing advantages of extrusion without heat, as well as minimal shrinkage in the final part. The shapes of the extruded parts have shown an excel-