Heat-resistant cross-linked polymers and the use thereof as binders

Cross-linked polymers which are linked by ester and/or urethane groups and which optionally contain amide and/or imide groups and/or isocyanurate and/or hydantoin rings in co-condensed form or are mixed with the corresponding polymers, wherein said cross-linking component is derived from N,N',N"-tris-hydroxyalkyl triazolidine-3,5-diones corresponding to the following general formula:

• ##STR17## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each independently represents hydrogen, an optionally substituted aliphatic, cycloaliphatic or atomatic radical and X represents O or S.