Polyurethane-urea elastomers prodn - by reacting a polyol, an aromatic diamine and an organic polyisocyanate in one step

摘要

Homogeneous polyurethane-urea reaction product is obtained by simultaneously reacting (a) a polyol having hydroxy functionality =2 and 40-100% pri. OH end grps. (b) an aromatic diamine having a reactivity equal to or less than that of methylene-bis(o-chloraniline) towards toluene-diisocyanate, and (c) an org. polyisocyanate; in presence of a catalyst comprising a tetra-substd. guanidine deriv. having formula (I) or an adduct of such deriv. and an org. isocyanate having functionality 1-3; in formula (I) R1,R2,R3 and R4 (same or different) are phenyl or 1-6C alkyls. One-step process is made possible by using this catalyst which establishes kinetic equilibrium between the hydroxylisocyanate reaction rate of the polyol and the faster amine-isocyanate reaction. Products are free of cloudiness, streaks and bubbles. Used for casting of film, coatings, castings.