Polyurethanes prepared from polyisocyanate, polyol and phosphonopolyester oligomers

A polyurethane prepared by reacting in the presence of a suitable catalyst system a composition comprising

• (A) an organic compound containing a plurality of --NCO or --NCS groups;
• with
• (B) a mixture of
• (1) a polyol containing from about 2 to about 8 active hydrogen groups per molecule and an average active hydrogen equivalent weight of from about 30 to about 3000;
• and
• (2) an oligomer or mixture of oligomers containing hydroxyl groups having recurring units represented by the following general formula ##STR5## wherein each A is independently --O--, --S--, --S--S--, ##STR6## or a divalent hydrocarbon group having from 1 to about 8 carbon atoms;
• each Q is independently oxygen or sulfur;
• each R is independently a hydrocarbon group having from about 1 to about 10 carbon atoms;
• each R' is independently a --CH.dbd.CH.sub.2 group or a --CXH--CXH.sub.2 group, wherein X is chlorine or bromine;
• each Z is independently a terminal moiety;
• each m is independently zero or one;
• each m' independently has a value from 1 to about 5;
• each n independently has a value of 2, 3 or 4;
• and x has an average value of from 1 to about 10;
• and wherein components (1) and (2) are present in quantities such that from about 0 to about 95 percent of the active hydrogen atoms are contributed by component (1) and from about 5 to about 100 of the active hydrogen atoms are contributed by component (2) and wherein components (A) and (B) are present in quantities such that the ratio of --NCO and/or --NCS groups to active hydrogen groups is from about 0.85:1 to about 4:1.