POLYURETHANE ELASTIC ARTICLES

1. A process for the production of optionally cellular elastic mouldings having a water-impermeable surface layer from polyurethane-polyurea elastomers by reacting a reaction mixture of (A) organic polyisocyanates and (B) difunctional or higher polyoxyalkylene-polyols containing more than 50% of hydroxyethoxy terminal groups containing primary hydroxyl groups (based on the total number of hydroxyl-group-containing terminal groups present) and having a hydroxyl number of from 22 to 35, a total ethylene oxide content of from 12 to 22% by weight (based on the total quantity of alkylene oxide present) and an average molecular weight of from 3 000 to 12 000, (C) difunctional or higher polyoxyalkylene-polyols containing from 80 to 100% of hydroxypropoxy terminal groups containing secondary hydroxyl groups (based on the total quantity of terminal groups present), (D) catalysts and/or combinations of catalysts, including organotin compounds and/or tertiary amines, (E) amine chain extending agents which are miscible in any ratio with components (B) and (C) and, optionally, (F) blowing agents, surfactants and/or agents for increasing fluidity, this reaction mixture being directly processed as a system by the reaction injection moulding (RIM) technique and the reactants being used in quantities which correspond to an isocyanate index of from 70 to 130, characterized in that the polyols (C) used are those which contain oxyethylene segments in a quantity of from 15 to 60% by weight (based on the total quantity of alkylene oxide present) in the copolymerized block of the polyol and which have a hydroxyl number of from 22 to 35 and an average molecular weight of from 3 000 to 12 000 and in that the polyol component is a mixture of (B) and (C) in a ratio by weight of from 1 : 9 to 9 : 1.