Foamed polyurethane-forming composition, foamed polyurethane and process making the same

A process for producing rigid formed polyurethanes suitable for model materials, which comprises dispersing an inert gas with mechanical stirring into a foamed polyurethane-forming composition, containing substantially no blowing agent, comprising:

• (1) an organic polyisocyanate component,
• (2) a polyol component comprising about 5-50% by weight of a high molecular weight polyol (A1) having a hydroxyl number less than about 300 and about 50-95% by weight of a low molecular weight polyol selected from the group consisting of polyhydric alcohols containing 3-8 hydroxyl groups and alkylene oxide adducts of said polyhydric alcohols (A2) having a hydroxyl number of at least 300, and
• (3) at least 1 part by weight, per 100 parts by weight of the polyol component, of a neutral or basic compound selected from the group consisting of hydroxides, oxides and salts of metals falling within the groups II, III and IV of the periodic table;
• or a mixture, double salt or complex containing these compounds.