Heat-curable compositions comprising low-temperature impact strength modifiers

A composition comprising:

• at least one epoxide adduct A having on average more than one epoxide group per molecule;
• at least one polymer B of the formula (I)
• in which:
• Y1 is an n-valent moiety derived from a linear or branched polyurethane prepolymer terminated with isocyanate groups by removal of the terminal isocyanate groups from the polyurethane prepolymer;
• Y2 is a moiety of an aliphatic, cycloaliphatic, aromatic or araliphatic epoxide containing a primary or secondary hydroxyl group after removal of the hydroxide and epoxide groups;
• n is 2, 3 or 4;
• m is 1, 2 or 3;
• and
• the at least one polymer B has at least one aromatic structural element, which is bound in the polyurethane prepolymer via urethane groups;
• wherein the Y1 moiety of the at least one polymer B simultaneously has at least structural elements of the formulae (IV) and (V)
• in which:
• p is 2, 3 or 4;
• q is 2, 3 or 4;
• X is S, O or NH;
• Ar1 is a p-valent, optionally substituted, aromatic moiety, wherein the aromatic moiety is directly bound to the urethane groups;
• Y3 is a q-valent moiety of an isocyanate-reactive polymer after removal of the terminal amino, thiol or hydroxyl groups;
• and
• * is the linkage point to the remainder of the polyurethane prepolymer,
• wherein the at least one polymer B is obtained from the reaction of a monohydroxyepoxide of the formula (II) and of a linear or branched polyurethane prepolymer terminated with isocyanate groups of the formula (III)
• wherein the polyurethane prepolymer of the formula (III) is obtained from the reaction of at least one polyisocyanate, at least one isocyanate-reactive polymer and at least one, optionally substituted, phenol selected from the group consisting of 1,4-dihydroxybenzene, 1,3-dihydroxybenzene, 1,2-dihydroxybenzene, 1,3-dihydroxytoluene, 3,5-dihydroxybenzoates, bis(4-hydroxyphenyl)methane (bisphenol F), bis(4-hydroxyphenyl) sulfone (bisphenol S), naphthoresorcinol, dihydroxynaphthalene, dihydroxy-anthraquinone, dihydroxybiphenyl, 3,3-bis(p-hydroxyphenyl)phthalides, 5,5-bis(4-hydroxyphenyl)hexahydro-4,7-methanoindane, phenolphthalein, fluorescein, 4,4′-[bis(hydroxyphenyl)-1,3-phenylenebis(1-methylethylidene)] (bisphenol M), 4,4′-[bis-(hydroxyphenyl)-1,4-phenylenebis(1-methylethylidene)] (bisphenol P), o,o-diallylbisphenol A, dicresols prepared by reacting cresols with diisopropylidenebenzene, phloroglucinol, gallic ester, cresol novolacs having an —OH functionality of from 2.0 to 3.5, and isomers thereof,
• at least one thixotropic agent C based on a urea derivative in a nondiffusing carrier material;
• and
• at least one curing agent D for epoxy resins, which is activated by elevated temperature.