Polyamide foams which inhibit the spread of fires for filling cavities in mining

A process for producing polyamide foams which do not propagate fire by mixing

• (i) a liquid isocyanate component which comprises at least one polyisocyanate and in which the molar ratio of aromatic isocyanate groups to the sum of aromatic and aliphatic isocyanate groups is at least 60 mol %
• with
• (ii) at least one liquid isocyanate-reactive component which comprises a reactive diluent, where the reactive diluent comprises
• (a) a chain-extending and/or crosslinking reactive diluent selected from the group consisting of aliphatic branched C24-66-polycarboxylic acids, alicyclic C24-66-polycarboxylic acids, partial esters of polycarboxylic acids having at least two unesterified carboxyl groups, and mixtures thereof and/or
• (b) a chain-terminating reactive diluent selected from the group consisting of aliphatic branched C24-66-monocarboxylic acids, alicyclic C24-66-monocarboxylic acids, partial esters of polycarboxylic acids having one unesterified carboxyl group, and mixtures thereof, and
• (iii) optionally a solid isocyanate-reactive component,
• where the liquid isocyanate-reactive component and/or the solid isocyanate-reactive component comprises an aromatic C8-18-polycarboxylic acid and/or an anhydride thereof;
• wherein the molar ratio of aromatic carboxyl groups to the sum of aromatic and aliphatic carboxyl groups in (ii) and (iii) is at least 10 mol %.