Munich-based Wacker will be premiering its highly heat resistant Elastosil R plus 4350/55 solid silicone rubber at this year’s Fakuma.
Heat stabilizers enable the extrudable and addition-curing solid silicone to withstand temperatures of up to 300 °C for several days, without any substantial modifications to its elasticity or mechanical properties.
Even temporary peaks of up to 400 °C pose no problem. The new solid silicone is therefore suitable for components used in oven and stove doors or in engine compartments, for example, which are exposed to heat repeatedly or over lengthy periods.
The grade can be used to produce heat-resistant tubing and sealing profiles, such as for oven and stove doors and engine-compartment parts.
Optimum properties are achieved through adding Elastosil Aux Stabilizer H series heat stabilisers to the base rubber. The type of stabiliser and the amount used have a significant influence on the thermal properties of the cured rubber.
The 4350/55 grade can be easily extruded to make extremely heat-resistant tubing and sealing profiles that withstand temperatures of up to 300 °C for several days – and even temperatures of up to 400 °C for short periods – without any damage.
Heat tests at 200 °C and 300 °C, respectively, show that key mechanical properties such as Shore hardness and elongation at break change very little even after 2,000 hours, i.e. 80 days. In this way, manufacturer’s specifications for products such as the sealing profiles used in modern ovens are clearly exceeded.
After it has cured, the silicone achieves a Shore A hardness value of 55, making it suitable for manufacturing heat-resistant profile gaskets, such as for oven and stove doors or for engine-compartment parts.
The new rubber also features good resistance to superheated steam, enabling its use in seals can also be used in applications that require resistance to both heat and superheated steam.
“Carefully” post-cured grades comply with the requirements of the German Federal Institute for Risk Assessment (BfR) and the US Federal Drug Administration (FDA) for food contact, Wacker concluded.