Vinyltris(2-methoxyethoxy)silane (A-172)

Vinyltris(2-methoxyethoxy)silane (A-172) is a vinyl-functional organosilane coupling agent with methoxyethoxy leaving groups that hydrolyze in water far more slowly than methoxy or ethoxy groups, making it highly stable in aqueous sizing bath formulations. This hydrolytic stability makes A-172 the preferred vinyl silane for continuous glass fiber wet sizing operations where the silane solution must remain stable for extended periods.

A-172 provides the same vinyl coupling chemistry as A-151 and A-171 — the vinyl group undergoes radical copolymerization with unsaturated polyester (UPR) and vinyl ester (VER) resin matrices during cure — but with dramatically improved bath life. In production sizing baths, A-172 solutions at 0.2–0.5% can remain effective for 8–24 hours compared to 2–4 hours for A-171 methoxysilane solutions. This is critical in high-throughput continuous fiber drawing operations.

In polyolefin crosslinking applications, A-172 is used to graft silane onto polyethylene (PE) and polypropylene (PP) through peroxide-initiated melt grafting (the Sioplas or Monosil process). The grafted vinyl groups provide subsequent moisture-crosslinkable silane-PE cable insulation compounds. A-172 can also be used in aqueous emulsion-based glass fiber mat binders and in surface treatment of glass fiber mats for open-mold hand layup applications where long working times are needed.