The adhesion promoter WACKER® Primer G 790 has proven indispensable in many industrial sectors and applications for the pretreatment of metallic and hard non-metallic substrates. It helps to achieve a strong and permanent adhesive bond to liquid silicone rubbers and other addition-curing silicone rubber compounds.
At K 2016, WACKER will launch a further development of the tried and tested adhesion promoter. WACKER® Primer G 790 toluene free has the same adhesion-promoting effect as its predecessor. It is also suitable for pretreating hard substrates such as aluminum, stainless steel, glass, epoxy resin and glass-fiber-reinforced plastic. However, the product differs in terms of the solvent composition. It contains no toluene or other aromatic compounds.
WACKER® Primer G 790 toluene free – a low-viscosity, yellowish solution – contains reactive silicone resins and organic silicates as adhesion-promoting active substances. A mixture of aliphatic hydro-carbons is used as a solvent. The solution is applied in extremely thin layers in a spraying or dipping process, or by brush on to the thoroughly cleaned substrates. Once the solvent has evaporated, the active substances crosslink under exposure to atmospheric moisture and form a silicone resin film that is chemically bonded to the substrate. A silicone rubber compound applied thereafter anchors itself to the film during its curing, resulting in a durable and stable metal, glass or plastic-silicone bond.
The possibility of forming a stable bond is essential when manufacturing two-component products. The substrate primed with the adhesion promoter can be used as the hard component in hard/soft combinations. It can therefore be inserted in the molding tool of an injection-molding machine, for example, and overmolded with a liquid silicone rubber. A sufficiently strong bond between silicone and the hard component can only be established after applying a prime coat.