Polyurethanes made using bismuth thiocarbamate or thiocarbonate salts as catalysts

A process for preparing a polyisocyanate-based polymer, comprising forming a reaction mixture containing at least one polyisocyanate, at least one isocyanate-reactive compound having at least two isocyanate-reactive groups and at least one catalyst, and then curing the reaction mixture in the absence of a blowing agent or frothing to form the polyisocyanate-based polymer, wherein the catalyst includes a bismuth salt of a mono- or dithiocarbonate compound, wherein the polyisocyanate-based polymer is a non-cellular cast elastomer, the polyisocyanate is a prepolymer or quasi-prepolymer having an isocyanate content of 8 to 18% by weight and the isocyanate-reactive compound is a chain extender or mixture of a chain extender and at least one polyol having a hydroxyl equivalent weight of at least 250.