Method for Producing Polyurethane Foams or Hydrogels by Employing Diol Containing Formulations

A process for producing polyurethane foams or polyurethane hydrogels, in which compositions comprising

• A) isocyanate-functional prepolymers obtainable by the reaction of
• A1) low molecular weight diisocyanates of molar mass from 140 to 278 g/mol, with
• A2) polyalkylene oxides having an OH functionality of two or more,
• A3) more than 1% by weight C2 to C12 diols based on total amount of isocyanate-reactive components A2) to A4) wherein component A3) differs from component A2),
• A4) optionally further isocyanate-reactive components differing from A2) and A3);
• B) water in an amount of at least 2% by weight, based on the total weight of the composition;
• C) optionally polyisocyanates obtainable by reaction of at least two low molecular diisocyanates, the diisocyanates having a molar mass of 140 to 278 g/mol,
• D) optionally catalysts;
• E) optionally salts of weak acids, corresponding free acids of which have a pKA in water at 25° C. of ≥3.0 and ≤14.0;
• F) optionally surfactants
• G) optionally mono- or polyhydric alcohols or polyols;
• H) optionally hydrophilic polyisocyanates obtainable by reaction of
• H1) low molecular weight diisocyanates of molar mass from 140 to 278 g/mol and/or polyisocyanates preparable therefrom and having an average isocyanate-functionality of 2 to 6 with
• H2) monohydroxyfunctional polyalkylene oxides of OH number from 10 to 250 and of oxyethylene unit content from 50 to 100 mol %, based on total amount of the oxyalkylene groups present,
• are provided, optionally foamed and cured wherein the isocyanate containing components do not exceed a residual diisocyanate content of 8% by weight, based on the total weight of the polyurethane foam or hydrogel.