Technology platform: addition curing silicones
Nano and Silicone Technology
Addition curing silicones are one of the most important elastomers for manufacturing medical products, electrical insulators, potting resins, and mold making compounds.
They can be used at temperatures between -60°C and 200°C, specialties even beyond these limits. They are formulated without using plasticisers and without tin compounds. Their curing mechanism allows the vulcanization of unlimited layer thickness in one step. Volume shrinkage is virtually zero as no cleavage products are liberated.
Evonik Hanse offers a comprehensive range of products for making addition curing silicone formulations. We enable you to individually adapt your product properties like viscosity, potlife and shore hardness, according to the particular requirements of your application.
Our applications lab is available to support you in designing and optimizing your formulation.
Linear, vinyl functionalized polydimethylsiloxanes are used as base polymers. They build the elastomeric network of the silicone rubber by means of a platinum catalyzed polyaddition reaction. The vinyl groups occur in three different constellations:
POLYMER VS has two terminal vinyl groups per chain. It is available in a wide range of viscosities (50 – 165000 mPas).
POLYMER RV additionally has several pendant vinyl groups along the chain. It allows the formation of very close meshed networks.
POLYMER MV is a mono vinyl terminated polymer. It acts as a reactive plasticiser which is connected to the network by one chain end. This anchoring avoids migration effect.
Product listing "Base polymers"
The CATALYST 500 series of products are dilute solutions of highly reactive platinum complexes. They enable the actual crosslinking reaction between vinyl polymers and SiH crosslinkers. Furthermore, they act as accelerators depending on the chosen dosage.
Evonik Hanse offers two different complexes. The divinyl tetramethyl disiloxane platinum(0) complex and the methylvinyl cyclosiloxane platinum(0) complex. They are available as solutions in POLYMER VS, divinyl tetramethyl disiloxane (DVS) and methylvinyl cyclosiloxane (MVC).
Product listing "Catalysts"
MODIFIER 700 series are SiH-terminated polydimethylsiloxanes being used as plasticizers. Due to their difunctional structure their reaction with vinylterminated silicones (POLYMER VS) leads to a chain extension instead of a crosslinking.
Using a MODIFIER decreases the network density and thus decreases the hardness of the resulting elastomer.
Product listing "Chain extenders"
Compounds are preparations of POLYMER VS and reinforcing fillers. They are used for manufacturing formulations with maximized mechanical properties (tensile strength, elongation). Using these compounds circumvents the handling of dry, dust-forming fillers during the formulation process.
COMPOUND VS are dispersions of surface-treated fumed silica in POLYMER VS.
The VQM series contains no macroscopic fillers but a vinyl-functional silicone resin. Thus it allows for crystal clear products.
Product listing "Compounds"
Inhibitors are used for adjusting the potlife of addition silicones. Evonik offers two different categories:
INHIBITOR MVC and DVS are pure silicone based inhibitors which regulate the activity of the platinum catalyst. They are used when exceptionally long potlives or very small inhibitor dosages are required.
INHIBITOR 600 is a ready to use mixture of various alkinol and silicone based inhibitors in POLYMER VS. It is appropriate for medium to short potlives and allows a very precise dosing in the formulation process.
Product listing "Inhibitors"
Vinyl-functional silicones (POLYMER VS) are crosslinked by reactive silicones bearing SiH groups (dimethylsiloxane methylhydrogensiloxane copolymers).
The CROSSLINKER 100 series of products have only pendant SiH groups along the chain. Products of the CROSSLINKER 200 series have additional terminal SiH groups for higher reaction rates (shorter potlives). These products are available in several viscosities and SiH contents.
Product listing "SiH Crosslinkers"