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Wacker’s headquarters in Munich, Germany

Wacker’s headquarters in Munich, Germany



Wacker develops new liquid silicone

Elastosil RT 728 can be injection moulded or mechanically dispensed straight onto the part to be sealed

August 2014

Munich-based chemical company Wacker is expanding its product range with a new liquid silicone rubber 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. 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.

Elastosil RT 728 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 Elastosil RT 728 exhibit no more than 30 per cent compression set after 1,000 hours in coolant at a temperature of 105°C. After 1,000 hours at 125°C, the permanent deformation is still less than 65 per cent as soon as the stress is removed. The elastomer’s high resilience delivers constant contact pressure and optimum leaktightness in the seal groove. Moreover, even long-term stress has very little effect on the overall property profile of the new product. Vulcanizates of the new liquid silicone meet delivery specifications of leading car manufacturers concerning gaskets for use in engine cooling systems.

Elastosil RT 728 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. It meets all the key requirements of this application. 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.

Earlier, Wacker developed a novel dispersible polymer powder for modifying cementitious and gypsum-based dry-mix mortars. Vinnapas 8620 E is based on a terpolymer of vinyl chloride, vinyl acetate and ethylene, and is ideal for the formulation of high-quality, low-emission tile adhesives. In the end product, the new dispersible polymer powder ensures a long open time and enhanced flexibility combined with excellent tensile adhesion strength, even after water or freeze/thaw conditions. With Vinnapas 8620 E in the formulation, it is thus even possible to reliably bond modern large-format or very thin tiles, and porcelain or natural-stone materials.

The new product is a dispersible polymer powder based on a novel vinyl chloride-vinyl acetate-ethylene-terpolymer for modifying modern cementitious and gypsum-based dry-mix mortars, particularly for tile adhesives. Vinnapas 8620 E ensures that tile adhesives adhere excellently to a broad range of different surfaces, including difficult ones such as fired tiles with high densities and natural-stone products – even after heat, water or freeze/thaw conditions. The dispersible polymer powder was specifically developed for the formulation of sophisticated tile adhesives of categories C2E or C2ES1 and C2ES2 as per EN 12004 that feature an extended open time and high flexibility. It thus offers users additional formulation reliability.

Wacker has upgraded its annual projection for Ebitda (earnings before interest, taxes, depreciation and amortisation). Ebitda for 2014 is now projected to be at least one third higher than last year’s €678.7 million ($914 million). Before this upgrade, Wacker had expected to surpass its 2013 Ebitda by at least 10 per cent. The upward revision is based on good business performance and strong demand, especially at Wacker Polysilicon, and success at reducing costs.




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