a negative - working , radiation - sensitive mixture is provided which contains an organic polymeric binder and a substance which converts radiant energy into heat , wherein the polymeric binder essentially comprises units of the formula : in which r 1 is a hydrogen atom or a alkyl radical , x is a single bond or a - valent radical of a alkane , in which individual methylene groups may be replaced by hetero atoms , of a alkene or of an isocyclic or heterocyclic , saturated or unsaturated , mono - or polycyclic ring or ring system , n is from 40 to 80 mol %, m is from 15 to 30 mol %, p is from 1 to 10 mol % and q is an integer from 1 to 3 , where q is equal to 1 when x is a single bond , and the polymeric binder has an acid number of from 5 to 150 . a recording material comprising a substrate and a layer of this mixture , and a process for the production of a color proof are also provided .