Evonik

Dynasylan SILBOND 40-HF

Ethyl polysilicates - higher flashpoint

Dynasylan SILBOND 40-HF is a clear, low-viscosity liquid with a minimum silica content of 40.0% (the Si content of Dynasylan SILBOND 40-HF is calculated as SiO2) and a flash point above 100° F (38° C), classifying it as a combustible liquid. This product is available to customers requiring a higher flashpoint than Dynasylan SILBOND 40.   

Key Features

Dynasylan SILBOND 40-HF is an ethyl polysilicate that is the partially hydrolyzed product of tetraethyl orthosilicate (TEOS). The partial hydrolysis of TEOS (Si[OEt]4) results in the conversion of ethoxy groups to hydroxyl groups forming silanols. Subsequent condensation of silanols will form siloxane bonds (-Si-O-Si-O-) and eventually cause the material to gel.    

Dynasylan SILBOND 40-HF is immiscible with water, therefore hydrolysis requires a cosolvent as a solubilizer. Mineral acids and ammonia are suitable as catalysts.          

Dynasylan SILBOND 40-HF or its hydrolysates are also the binder component for 1- and 2-pack inorganic zinc-rich coatings, for corrosion protection on steel, and for slurries used in precision investment castings.

Recommended Applications

Dynasylan SILBOND 40-HF is often used as an intermediate, which is further hydrolyzed to produce a binder that can be used for many applications. Several of these end-uses include inorganic zinc-rich primers, investment casting molds, cores and ceramic shapes, coatings, and thermal insulation.

Similar to Dynasylan SILBOND Condensed and Dynasylan SILBOND 40, Dynasylan SILBOND 40-HF is used to deposit silicic acid formed as a result of complete hydrolysis. The resulting silicic acid bonds well to many inorganic substrates, such as glass, ceramic, metal, fillers, pigments, and synthetic fibers. The deposition of a thin SiO2layer improves the chemical and thermal stability and mechanical properties.          

Other applications are:     

  • Binder, especially for inorganic zinc-rich coatings or precision investment castings     
  • Encapsulant for hydroxyl poor fillers to enhance adhesion with functional silanes     
  • Crosslinker component in cold-curing silicone rubber systems     
  • Hardening component in dentistry for impression materials and as a binder for embedding material        

Dynasylan SILBOND 40-HF is also used as starting material for sol-gel processes. It is usually used in conjunction with alkylsilanes (e.g. Dynasylan MTES) organofunctional silanes and/or organic precursors (e.g. organic resins) to form siloxane networks. This makes it possible to obtain highly scratch-, abrasion-, and chemical-resistant coatings.