MUNICH-based chemical firm, Wacker Chemie AG, will be presenting a tin-free catalyst for condensation-curing silicone rubber grades at the upcoming K 2013 show in Düsseldorf, Germany this October.
According to the company’s press release, the ELASTOSIL Catalyst NEO, was tailored specifically for all of the base components of ELASTOSIL M mouldmaking compounds. Silicone rubbers catalysed with this product can be processed normally and possess the same mechanical properties as compounds cured with standard catalysts. Since its application is not subject to legal restrictions, ELASTOSIL Catalyst NEO represents a practical alternative to conventional, tin-based catalysts.
Under its ELASTOSIL M brand, Wacker markets a wide range of two-part silicone elastomers for mouldmaking and encapsulation applications.
The new catalyst enables industrial and commercial users to switch their mouldmaking and encapsulation processes over to completely tin-free systems. Free of organo-tin catalysts, it is not affected by EU restrictions dating from 2012 on mouldmaking compounds containing dibutyltin or dioctyltin. The EU regulation prohibits manufacturers from selling such products with more than 0.1 wt % tin to individuals and/or hobby users.
Used in relatively small proportions, the second component of room-temperature-curing silicone rubber consists of a curing agent and a catalyst that drives the crosslinking reaction at a rate appropriate to the application. The new catalyst is formulated to provide a sufficiently long pot life for making molds of large objects. At the same time, it ensures that compounds cure within 24 hours.
Because condensation-curing 2-part compounds cure at room temperature in the presence of humidity, no complex equipment is required to process them. Their primary application is making moulds of technical items, objects of art and archaeological artifacts, with the silicone rubber forming the negative mould of the object to be reproduced. Condensation-curing RTV-2 compounds can also be used for encapsulating electronic components and assemblies.