Wacker, the Munich-based chemical company, will present first-ever hybrid polymers for structural adhesive bonds at the World Adhesive & Sealant Conference WAC2012. The novel polymers are based on the alpha-silane technology and are available as grades of the new Geniosil® XB product line. They cure on contact with atmospheric moisture to form thermosets, thus achieving the high Shore-D strength needed for structural adhesives. This provides adhesives manufacturers with an alternative to traditional binder materials. Adhesive binders based on Geniosil® XB pose no health risks, meet high technical requirements and offer manufacturers a wide range of formulation options. WAC2012 takes place in Paris from September 18 to 21.
The Geniosil® XB product line is a range of alpha-silane-terminated polyethers. The polymers are of low viscosity and feature a high density of crosslinkable silyl groups. This high silyl group density produces a close-meshed three-dimensional network on curing. Depending on the formulation, hardnesses are in the high Shore-D range – levels never before achieved with silane-terminated polyethers.
Their low viscosity makes the new hybrid polymers easy to handle and process. In particular, they can be formulated without using
plasticisers or solvents. Tin catalysts can now also be dispensed with – yet another advantage of using alpha-silane technology. Tin-free formulations eliminate incompatibilities with ester-based additives, thereby widening the formulation scope and enhancing the shelf life of the adhesive.
Adhesives formulators can modify the mechanical end properties and the adhesive strength in the formulation for precise adjustment in line with requirements. In terms of adhesive strength and flexibility, the cured adhesives are making advances into what used to be the exclusive domain of epoxy-based, isocyanate-curing systems. Depending on the substrate, adhesives formulated using Geniosil® XB can attain adhesive strengths of up to 15N/mm2. For instance, a glue dot one centimeter in diameter between two beech panels is able to carry loads of up to 120kg. Geniosil® XB is also suited for making waterproof wood adhesives that satisfy durability classes D1 through D4 (DIN EN 204).
The new binder technology makes structural adhesives especially easy to use. They cure without bubbling and gain strength quickly; they adhere to many commonly used materials such as wood, glass, metals and ceramics with no need for primers. Adhesives based on Geniosil® XB can be applied and processed just like conventional polyurethane-based products.
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A special supplement for WAC2012 is being produced by PPCJ in which a technical article on Geniosil will appear. This will be published with the August issue of PPCJ and distributed to delegates at WAC2012.