Munich-based chemical company Wacker has expanded its product range with a new liquid silicone rubber (LSR) for the production of automotive gaskets. MoUlded parts made from the new silicone are resistant to heat and coolant and exhibit low compression set even under permanent stress, says Wacker. Car radiators and cooling-system components can thus be reliably sealed.
Elastosil RT 728, as the new silicone grade is called, can be injection moulded or mechanically dispensed straight onto the part to be sealed. It has been chiefly developed for the production of fluid- and heat-resistant gaskets for the automotive industry. The liquid silicone is characterised by high coolant resistance.
Gaskets made from the new LSR are said to exhibit no more than 30% compression set after 1000 hours in coolant at a temperature of 105°C. After 1000 hours at 125°C, the permanent deformation is still less than 65% as soon as the stress is removed. The elastomer’s high resilience delivers constant contact pressure and optimum leak tightness in the seal groove. Moreover, even long-term stress has very little effect on the overall property profile of the LSR.
Vulcanisates of the new liquid silicone meet delivery specifications of leading car manufacturers concerning gaskets for use in engine cooling systems.
The new material supports cost-efficient series production of parts by injection moulding. However, the liquid silicone can also be applied by dispensing equipment straight onto the part to be sealed – automotive subcontractors use this method to produce two-component parts. By virtue of its shear-thinning properties, it can be applied by dispensing equipment and is self-adhesive. Automotive suppliers, such as Stuttgart-based MAHLE, uses the product to make radiator components.