Catalyst system for injection molding polyurethanes

Claim 1

A process for preparing polyurethane elastomers which comprises combining: a. at least one polyether diol, polyester diol or mixture thereof, at least one organic bifunctional extender selected to be a diamine, aminoalcohol or glycol having a rate of reactivity greater than the alkylene glycols and the hindered amines, and a catalytically effective amount of a catalyst system comprising per 100 parts of polymerization mixture, i. 0.2 parts of triethylenediamine ii. 0.6 parts of an organometallic catalyst selected to be a dialkyltin diazelate, phenyl mercuric propionate, or combination thereof, and iii. at least 0.8 parts of a basic amine catalyst selected to be N-methyldicyclohexyl amine, an N-alkylmorpholine, or a combination thereof; and b. a prepolymer resulting from the reaction of at least one polyether diol, polyester diol or mixture thereof with at least one organic diisocyanate in proportions such that the ratio NCO/OH is greater than about 2:1 in a mixing and injecting apparatus under a mixing screw speed in excess of 10,000 r.p.m., injecting the liquid mixture into a mold and curing the contents of the mold.