A polymer comprising the addition reaction product of a polyisocyanate
having a functionality of from 2 to 10 and a succinylpolyether having a
C.sub.6-30 -alk(en)yl group and at least one group which is capable of
reacting with the polyisocyanate and where the number of recurring
ethyleneoxy groups in the polyether is from 4 to 800.
