Abstract
Novel alkoxysilane-terminated polyurethanes (silylated polyurethanes) were synthesized from isocyanateterminated polyurethane and silane endcappers having alkoxysilyl group. The silane endcappers were also synthesized by the conjugate reaction of 3-aminopropyltrialkoxysilane with acrylate monomers. The viscosities of the obtained silylated polyurethanes were lower than that of silylated polyurethane derived from untreated 3-aminopropyltrialkoxysilane. The silylated polyurethanes were evaluated by the curing speeds and the bond strengths to four adherends. Shorter alkyl groups of starting acrylate monomers led to higher curing speed. The tensile shear bond strength and adherence depended on trialkoxysilane end-capping ratio. The effects of BF3-monoethylamine complex (BF3-MEA) and dibutyltin dimethoxide (DBTDM) on the curing speeds and thermal stabilities were examined. BF3-MEA was significantly superior to DBTDM in terms of both the catalytic effect to cure the silylated polyurethanes and the thermal stability of cured silylated polyurethanes. The obtained silylated polyurethanes are useful as base polymers of environmentally-friendly moisture-curable adhesives, and BF3-MEA is an effective curing catalyst for the silylated polyurethanes.
