Abstract: The present invention relates to a use of at least one homopolymer or copolymer which is obtainable by polymerizing ethylenically unsaturated monomers and which is composed of at least one structural unit (W0) or of at least two structural units (W1) and (W2) differing from one another, and also optionally of at least one other structural unit (W3) differing from (W0), (W1) and (W2), where each structural unit (W0) contains not only at least one functional group comprising at least one phosphorus atom, but also at least one functional group reactive towards an isocyanate group, each structural unit (W1) has at least one functional group having at least one phosphorus atom, each structural unit (W2) has at least one functional group reactive towards an isocyanate group, where none of the structural units (W2) comprises phosphorus atoms, and the homopolymer or copolymer contains, relative to the total quantity of the at least one structural unit (W0) within the main polymer chain of the homopolymer or copolymer