WACKER ELASTOSIL AUX G3242 20kg – Primer, Adhesion Promoter for Improving Silicone Adhesion to Surfaces

ELASTOSIL® AUX G 3242 is a solvent-based mixture of siloxanes and reactive silanes used as an adhesion primer for silicone rubbers. The product provides excellent adhesion to a wide range of substrates, such as metals, ceramics, glass and other polymeric materials, enabling effective bonding with subsequently vulcanized ELASTOSIL® R solid silicone elastomers of the HCR/HTV type cured with peroxides. After the solvents evaporate, a rigid silicone resin layer forms on the substrate surface under the influence of atmospheric humidity. This layer adheres firmly to a broad variety of materials and acts as an adhesion promoter for the silicone rubbers applied afterwards. The primer is colorless to yellowish, has a density of approximately 0.8 g/cm³, a solids content of 7 % and a low kinematic viscosity of about 5 mm²/s. Its solvent is a mixture of Isopar E and xylene. It can be applied directly or in diluted form using various methods such as coating, dipping, brushing or spraying, and can be further diluted with organic solvents if required. The primer layer should be as thin as possible, typically in the range of 1–10 µm, corresponding to a coating weight of 5–50 g/m². Prior to application, thorough cleaning of the surface is recommended. After application, the solvent should be allowed to evaporate at room temperature and moderate atmospheric humidity for at least 2 hours, after which the silicone rubber should be applied as soon as possible, and no later than within 2 days. In some cases, adhesion can be further improved by heating the primed substrate to 100–150 °C. The primer is a general-purpose product that is sensitive to moisture; therefore it should be stored in a tightly closed container and thoroughly mixed before use.