| abstract |
The invention relates to a method for producing elastic, weather-resistant sheet-like structures by mixing a moisture-curing polyurethane binder, which is a prepolymer based on aromatic polyisocyanates and polyols, with rubber and / or elastomeric plastic granules and, if appropriate, further additives and auxiliaries, shaping and The mixture cures under the influence of moisture. The method is characterized in that the moisture-curing prepolymer. a) reacting tolylene diisocyanate with a polyol at an NCO / OH ratio of at least 1: 1 and, if excess tolylene diisocyanate monomers are still present after the reaction, removing them to below 1% of free tolylene diisocyanate, and b) subsequently reacting the reaction product Step a) with diphenylmethane diisocyanate and a polyol in quantities such that the prepolymer has 5-15% by weight of free NCO groups and contains less than 1% of free tolylene diisocyanate. |