Wacker Chemie AG will present its first hybrid polymers for structural adhesive bonds at the World Adhesive & Sealant Conference WAC 2012, to be held from September 18-21 in Paris, France.
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, according to Wacker, levels never before achieved with silane-terminated polyethers.
Their low viscosity makes the new hybrid polymers easy to handle and process, which can be formulated without using plasticizers or solvents. Tin catalysts can now also be dispensed with. 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, Wacker notes adhesives formulated using Geniosil XB can attain adhesive strengths of up to 15N/mm2. For example, a glue dot 1cm 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 and adhere to many commonly used materials such as wood, glass, metals and ceramics with no need for primers, adds Wacker. Adhesives based on Geniosil XB can be applied and processed like conventional polyurethane-based products.