MODIFIED EPOXY RESIN

Compositions containing A) a liquid copolymer based on butadiene, a polar, ethylenically unsaturated comonomer and optionally a further ethylenically unsaturated comonomer, and B) a compound of the formula I in which m is 2 to 6, R is the m-valent radical, after removal of the terminal isocyanate, amino or hydroxyl groups, of an elastomeric prepolymer which is soluble or dispersible in epoxy resins, X is -O- or -NR - where R is hydrogen, C1-C6-alkyl or phenyl, Y is -O-, R is the radical of a monophenol or of an aliphatic or cycloaliphatic mercapto alcohol after removal of a hydroxyl group, or Y and R together are the radical of an aliphatic lactam which is linked to the carbonyl group via the nitrogen atom, with the proviso that at least one of the groups -X- and -Y-R contains a nitrogen atom, can be employed for rendering epoxy resins flexible.d