Process for producing molded polyurethane parts

In a process for producing molded polyurethane parts by reacting at least one polyol with an organic di- or polyisocyanate in the presence of catalysts and an internal release agent while molding the product, the improvement which comprises using as the internal release agent 0.5 to 10 weight percent, based on the weight of the reaction mixture, of a compound having the average formula:

• ##STR18## in which R.sup.1 may be the same or different and represents an alkyl radical with 1 to 18 carbon atoms or an aryl radical, at least 70% of the R.sup.1 radicals being methyl radicals;
• R.sup.2 is the same as R.sup.1 or represents one of the following radicals, ##STR19## in which R.sup.3 is a divalent hydrocarbon radical with 2 to 4 carbon atoms,
• R.sup.4, R.sup.5 are univalent hydrocarbon radicals or, taken together are part of a morpholine or a piperazine ring,
• R.sup.6 is a low molecular weight alkyl radical with 1 to 4 carbon atoms,
• R.sup.7 is a hydrogen, acyl or R.sup.6 radical,
• z=1 to 10
• n=1 to 20 and
• m=1 to 20,
• with the proviso that, in the average molecule, at least one R.sup.2 radical represents the ##STR20## x=20 to 300 and y=1 to 20.