Dynasylan® SILBOND® Condensed is a ready source of silicic acid for many applications. Silicic acid is usually obtained by hydrolysis, or thermally by condensation at elevated temperatures. The resulting silicic acid bonds well to many inorganic substrates and can be deposited in-situ in a controlled manner. The surfaces of glass, metals, pigments, fillers, and synthetic fibers can be coated withy a very thin SiO2 layer in order to improve chemical and thermal stability, and mechanical properties.
Other applications are:
binders for fillers in inorganic zinc-rich paints or precision investment castings
crosslinkers in silicone rubber systems
drying agents in sealing compositions
Dynasylan® SILBOND® Condensed is an important starting material for sol-gel processes, where the additional use of alkylalokoxysilanes (e.g. Dynasylan® MTES) can give the siloxane network a slight organic character as a result of the incorporation of alkyl groups.
It is also possible to construct an inorganic/organic network by adding silanes containing organofunctional groups (e.g. aminopropyl groups) and polymerizing with organic precursors. This principle makes it possible to obtain highly scratch- and abrasion-resistant coatings.
Dynasylan® SILBOND® Condensed is immiscible with water, so hydrolysis requires the use of a co-solvent such as ethanol. Suitable catalysts are mineral acids or ammonia, or even acetic acid and amines.
Partial hydrolysis gives hydrolysates of Dynasylan® SILBOND® Condensed whose shelf-life depends on the amount of water and solvent used. The amount of water determines the activity of the hydrolysate. Activity and shelf-life are inversely proportional. The correct choice for the amount of water can give hydrolysates, which have a shelf-life of up to a year (from the time of manufacture).