Thus, examples of such catalysts include for group (i) such compounds as aluminum, zinc, iron and cobalt acetylacetonates; for group (ii) dicyandiamide; for group (iii) such compounds as 2-methylimidazole, 2-ethyl-4-methylimidazole and 1-cyanoethyl-2-propylimidazole; for group (iv) such compounds as benzyldimethylamine, and 1,2-diaminocyclohexane; for group (v) such compounds as trifluoromethanesu