Polyhydroxyalkyl polycarbonamides for the production of flame-resistant polyurethane rigid foams and integral foams

In a process for the production of flame-resistant polyurethane rigid foams and/or polyurethane integral skin foams by the reaction of relatively high molecular weight compounds containing at least two isocyanate reactive hydrogen atoms with polyisocyanates and optionally chain lengthening agents having molecular weights of from 32 to 399, and optionally in the presence of catalysts and organic blowing agents, the improvement wherein the reaction mixture contains reactive flame-retarding agents, said agents being the poly-bis-(N,N-hydroxyalkyl)-amides of polybasic aliphatic or cycloaliphatic carboxylic acids corresponding to the following formula:

• ##STR24## wherein n represents an integer from 2 to 6;
• X is selected from the group consisting of a bond (when n=2), a n-valent alkane group optionally substituted with hydroxyl groups, and a C.sub.4 -C.sub.6 -cycloalkane group in which the ring may contain heteroatoms and A represents a straight chained or branched C.sub.2 -C.sub.6 -alkylene group optionally containing a hydroxyl group, said agents being used in quantities of from 11.5 to 50 parts by weight, based on 100 parts by weight of the relatively high molecular weight polyol.