| abstract |
In one aspect, this invention is a polyurethane sealant composition comprising (1) a urethane prepolymer having an isocyanate functionality of at least about 2.0 and a weight average molecular weight of at least about 2,000; and (2) a catalytic amount of (a) a substantially active hydrogen free glycol acid salt of a tertiary amine and an organo metallic compound, (b) a mixture of a substantially active hydrogen free glycol acid salt of a tertiary amine and an organo metallic compound and a second organometallic compound, or (c) a mixture of an organometallic compound with dimorpholinodialkyl ether or an dialkylmorpholinodialkyl ether. In another embodiment, the polyurethane sealant composition further comprises (A) a silane, or (B) an adduct of an isocyanate reactive silane and a polyisocyanate, (C) the reaction product of an isocyanate reactive silane or an adduct of an isocyanate reactive silane and a polyisocyanate with a polyisocyanate and an active hydrogen containing compound or a polyurethane prepolymer which has free isocyanate moieties; which reaction product has an average of at least one silane group and at least one isocyanate group per molecule. In another embodiment the invention is a method for bonding glass to a substrate which comprises contacting a sealant according to the invention with glass and another substrate with the sealant disposed between the glass and substrate and thereafter allowing the sealant to cure so as to bind the glass to the substrate. The sealant composition of the invention is useful in bonding glass substrates to metal plastic, fiberglass or composite substrates, which may or may not be painted. It has been discovered to give unexpectedly high lap shear strength when no primer compositions have previously been applied to the painted plastic, metal, fiberglass or composite substrate. |