At European Coatings Show 2015, Munich-based chemical group Wacker will unveil new silane-terminated polymers for the formulation of industrial adhesives and for sealing flat surfaces. Known as Geniosil XT, the new binder makes it possible to produce materials that are extremely tear-resistant and at the same time highly elastic. This combination of properties unlocks applications in automotive and mechanical engineering that were previously closed to silane-curing polymers. The European Coatings Show will be held in Nuremberg, Germany, from April 21 to 23.

Geniosil XT 50 and Geniosil XT 55 are based on silane-modified polyethers with a high density of crosslinkable silyl groups which cure to a tight-mesh network that is very strong but elastic. Adhesive layers and sealing membranes formulated with Geniosil XT possess high strength. However, Wacker says they are also highly ductile and will tear only when subjected to strong forces. Damaged material exhibits no tendency to tear propagation.

Geniosil XT thus represents the first technically equivalent alternative to conventional polyurethane-based systems. These new polymers are ideal for applications that repeatedly subject them to dynamic forces, such as vibrations in vehicles and washing machines. Up to now, applications of this kind were essentially the domain of isocyanate-curing polymer systems.

Furthermore, Geniosil XT’s low viscosity makes it easy to process at low temperatures. The binders can be formulated with and without plasticizers or fillers, and blends can be produced in any color. The compounds can be formulated for adhesion to many conventional substrates, such as metals, glass, cement, glazed tiles, wood, polycarbonate, and polymethyl methacrylate. Priming is unnecessary. As the polymers are also miscible with all other Geniosil silane-terminated polyethers, compounders can vary the properties over a wide range of formulations. Typical end products are industrial adhesives, liquid waterproofing systems, and coatings.

Geniosil XT 50 is an alpha-silane-terminated polymer and lends itself to the production of tin-free adhesives and crack-bridging liquid waterproofing systems. These can possess tensile strengths of up to 9 N/mm2 and tear strengths of up to 50 N/mm (measured in accordance with ASTM D 624 B-91). What is more, Geniosil XT 50 can be formulated without fillers to make transparent, tin-free end products that have good mechanical properties.

Geniosil XT 55 is a gamma-silane-terminated polyether. It can yield shear strengths of over 5 N/mm2 combined with elongation at break of around 700 percent, the exact values depending on the formulation. Such formulations are also notable for their high tear strength and high elastic recovery. The polymer is therefore ideal for the production of high strength, yet extremely flexible industrial adhesives of the kind used, for example, in direct glazing of windshields in the automotive industry.