Composition comprising a) at least one polyisocyanate P having aromatic isocyanate groups, and b) at least one dialdimine A of the formula, where X is the radical of a diamine DA with two primary amino groups after the removal of these two amino groups; and Y 1 and Y 2 are either each independently a monovalent hydrocarbon radical having 1 to 12 carbon atoms, or together are a divalent hydrocarbon radical which has 4 to 20 carbon atoms and is part of an optionally substituted carbocyclic ring having 5 to 8, preferably 6, carbon atoms; and Y 3 is a monovalent hydrocarbon radical which optionally has at least one heteroatom, especially oxygen in the form of ether, carbonyl or ester groups; with the proviso that at least one of the two primary amino groups of the diamine DA is an aliphatic amino group, and the two primary amino groups of the diamine DA differ from one another either in the number of hydrogen atoms on the carbon atoms (C α) in the α position to the particular amino group by at least one or in the number of hydrogen atoms on the carbon atoms (C β) in the β position to the particular amino group by at least two. a) at least one polyisocyanate P having aromatic isocyanate groups, and b) at least one dialdimine A of the formula, where X is the radical of a diamine DA with two primary amino groups after the removal of these two amino groups; and Y 1 and Y 2 are either each independently a monovalent hydrocarbon radical having 1 to 12 carbon atoms, or together are a divalent hydrocarbon radical which has 4 to 20 carbon atoms and is part of an optionally substituted carbocyclic ring having 5 to 8, preferably 6, carbon atoms; and Y 3 is a monovalent hydrocarbon radical which optionally has at least one heteroatom, especially oxygen in the form of ether, carbonyl or ester groups; with the proviso that at least one of the two primary amino groups of the diamine DA is an aliphatic amino group, and the two primary amino groups of the diamine DA differ from one another either in the number of hydrogen atoms on the carbon atoms (C α) in the α position to the particular amino group by at least one or in the number of hydrogen atoms on the carbon atoms (C β) in the β position to the particular amino group by at least two. where X is the radical of a diamine DA with two primary amino groups after the removal of these two amino groups; and Y 1 and Y 2 are either each independently a monovalent hydrocarbon radical having 1 to 12 carbon atoms, or together are a divalent hydrocarbon radical which has 4 to 20 carbon atoms and is part of an optionally substituted carbocyclic ring having 5 to 8, preferably 6, carbon atoms; and each independently a monovalent hydrocarbon radical having 1 to 12 carbon atoms, or together are a divalent hydrocarbon radical which has 4 to 20 carbon atoms and is part of an optionally substituted carbocyclic ring having 5 to 8, preferably 6, carbon atoms; and Y 3 is a monovalent hydrocarbon radical which optionally has at least one heteroatom, especially oxygen in the form of ether, carbonyl or ester groups; with the proviso that at least one of the two primary amino groups of the diamine DA is an aliphatic amino group, and the two primary amino groups of the diamine DA differ from one another either in the number of hydrogen atoms on the carbon atoms (C α) in the α position to the particular amino group by at least one or in the number of hydrogen atoms on the carbon atoms (C β) in the β position to the particular amino group by at least two. in the number of hydrogen atoms on the carbon atoms (C α) in the α position to the particular amino group by at least one or in the number of hydrogen atoms on the carbon atoms (C β) in the β position to the particular amino group by at least two.