Process for the production of elastic shaped articles

A process for the production of optionally cellular, elastic, shaped articles having an impervious surface layer of polyurethane-polyurea elastomers by reacting a reaction mixture comprising:

• (A) an organic polyisocyanate;
• (B) an ethylene oxide-tipped difunctional or higher functional polyoxyalkylene polyol having a hydroxyl number of from about 22 to about 35 and a total ethylene oxide content of from about 12 to about 22% by weight, based on the total amount of alkylene oxide present in said ethylene oxide-tipped polyol;
• (C) a propylene oxide-tipped difunctional or higher functional polyoxyalkylene polyol containing oxyethylene segments in the internal block of the polyol in a quantity of from 15 to 60% by weight, based on the total amount of alkylene oxide present in said propylene oxide-tipped polyol, and having a hydroxyl number of from about 22 to about 35;
• (D) a catalyst;
• (E) an aromatic amine chain extender, said amine being miscible with components (B) and (C), in any proportion, and optionally;
• (F) blowing agents, surfactants and/or flow enhancing agents;
• said reaction mixture being processed as one-shot systems by the reaction injection molding technique (RIM process) and said reactants being used in quantities corresponding to an isocyanate index of from 70 to 130, further characterized in that (i) the polyols (B) and (C) are used in a weight ratio less than or equal to 5:1, and (ii) the composition and proportions of (B) and (C) are selected such that the total concentration of oxyethylene groups in the final polyurethane is from about 7 to about 14% by weight.