Abstract: Urea-modified bubble-free moldings based on polyisocyanate polyaddition products are made by reacting (a) an organic polyisocyanate with (b) a polyhydroxyl compound and/or polyepoxide in the presence of (c) a water chain extender in the form of an aqueous alkali aluminosilicate or an aqueous alkali-alkaline earth aluminosilicate of the zeolite type in a mold using cast resin technology. The reaction components are used in quantities such that the equivalent ratio of isocyanate to hydroxyl and/or epoxide groups is from 1.1:1 to 6.1. The chain extender is used in a quantity such that the amount of water is at least equivalent to the excess of isocyanate. These moldings may be made by a one-shot or a two-shot process. These moldings are characterized by better mechanical properties such as tensile strength and elongation than prior art moldings.

Abstract: The instant invention is directed to a process for the solvent-free production of solid polyurethane moldings wherein the polyisocyanate used is a polyisocyanate mixture containing from 10 to 80% by weight of 2,4'-diisocyanatodiphenylmethane.

Abstract: A shaped polyurethane product having improved arc-resistance, current leakage properties and dimensional stability which adapt it to be used as an electrical insulator is made by shaping a reactive mixture containingA. a polyisocyanate having only cycloaliphatic isocyanato groups,B. a polyisocyanate having only cycloaliphatic and aliphatic isocyanato groups, orC. a mixture of (a) or (b) with an aliphatic polyisocyanate, with a polyol mixture containingD. 5 to 30 percent by weight, based on the total weight of the polyol mixture of a polyol or polyol mixture having a molecular weight below about 1000 in which the hydroxyl groups are only cycloaliphatically or aliphatically bound and at least 50% thereof are cycloaliphatically bound; andE. 70 to 90 percent by weight of a polyol or polyol mixture having a molecular weight below 1000 in which the hydroxyl groups are substantially all aliphatically bound.