polyurethanes and polyesters are described which are the reaction products of an aromatic , aliphatic or cycloaliphatic diisocyanate , or of a diacid or diacid derivative respectively , with a diol containing a pendent uv - absorbing moiety , optionally also with one or more other diols or diamines . these uv - absorbing polycondensates can be applied to the surfaces of substrates by exhaustion methods or by spraying and act to protect polymers and dyes from degradation by uv radiation . they are therefore useful , either alone or in combination with other coating materials , for the treatment of wood , paper , textiles , leather or other surfaces which are exposed to degrading radiation .