Process for the preparation of molded parts of polyurethane or polyurethane-polyurea employing monocyclic amidines

In a process for the preparation of molded parts of polyurethane-polyurea reacting an organic aromatic polyisocyanate, a polyol and a chain extender in the presence of a catalyst, optionally in the presence of blowing agents, auxiliaries and additives, the improvement comprising employing as catalyst a monocyclic amidine having the formula ##STR28## wherein R.sup.1 is hydrogen or R.sup.2 ;

• n represents a whole number from 3 to 12,
• R.sup.2 denotes a linear or branched alkyl radical with 1 to 20 carbon atoms, a linear or branched OH--, NH.sub.2 --, --NH-- and/or SH-group-containing alkyl radical having 1 to 20 carbon atoms, a cycloalkyl radical with 5 to 12 carbon atoms, in which one or more methylene groups may be substituted by --O--, --S--, --NH--, --CO-bridge members, a cycloalkyl radical with 5 to 12 carbon atoms substituted with linear or branched alkyl groups with 1 to 6 carbon atoms, a cyclohexyl radical, --OH--, --NH.sub.2 -- or --SH-- groups wherein one or more methylene groups can be substituted by --OH--, --S--, or --NH-members, an aromatic radical with 6 to 15 carbon atoms, an aromatic radical with 6 to 15 carbon atoms substituted with linear or branched alkyl groups with 1 to 6 carbon atoms, --OH--, --NH.sub.2 --, --NHCH.sub.3 --, --N(CH.sub.3).sub.2 -- or --SH-groups, an aralkyl radical having 7 to 11 carbon atoms wherein the radicals R.sup.1 and R.sup.2 are the same or different or wherein together form a ring with 4 to 12 carbon atoms in which one or more methylene groups may be substituted by --O--, --S--, --NH--, --CO-bridge members, and which optionally contain linear or branched alkyl radicals having 1 to 6 carbon atoms, or carboxylic acid ester groups in bonded form as substituents.