Aldimine of the formula where A is either the radical of an amine after removal of n primary aliphatic amino groups and m HX groups, or together with R 7 is an (n+2)-valent hydrocarbon radical which has 3 to 20 carbon atoms and optionally contains at least one heteroatom; n is 1 or 2 or 3 or 4, and m is 0 or 1 or 2 or 3 or 4, with the proviso that m+n is 2 or 3 or 4 or 5; R 1 and R 2 are either each independently a monovalent hydrocarbon radical having 1 to 12 carbon atoms, or together are a divalent hydrocarbon radical having 4 to 12 carbon atoms which is part of an optionally substituted carbocyclic ring having 5 to 8 carbon atoms; R 3 is a hydrogen atom or an alkyl group or an arylalkyl group or an alkoxycarbonyl group; R 4 and R 5 are either each independently a monovalent aliphatic, cycloaliphatic or arylaliphatic radical which has 1 to 20 carbon atoms and is free of hydroxyl groups and optionally contains heteroatoms in the form of ether oxygen or tertiary amine nitrogen, or together are a divalent aliphatic radical which has 3 to 20 carbon atoms and is part of an optionally substituted heterocyclic ring having 5 to 8 ring atoms, this ring being free of hydroxyl groups and, as well as the nitrogen atom, optionally containing further heteroatoms in the form of ether oxygen or tertiary amine nitrogen; X is O or S or N-R 6 or N-R 7, where R 6 is either a monovalent hydrocarbon radical which has 1 to 20 carbon atoms and optionally has at least one carboxylic ester, nitrile, nitro, phosphonic ester, sulfone or sulfonic ester group, or a substituent of the formula where p is 0 or an integer from 1 to 10 000, and B is a (p+1)-valent hydrocarbon radical which optionally contains ether oxygen, tertiary amine nitrogen, hydroxyl groups, secondary amino groups or mercapto groups; and R 7 together with A is an (n+2)-valent hydrocarbon radical which has 3 to 20 carbon atoms and optionally contains at least one heteroatom; wherein the aldimine of the formula is nt one of the following compounds: and L-H = and A is either the radical of an amine after removal of n primary aliphatic amino groups and m HX groups, or together with R 7 is an (n+2)-valent hydrocarbon radical which has 3 to 20 carbon atoms and optionally contains at least one heteroatom; n is 1 or 2 or 3 or 4, and m is 0 or 1 or 2 or 3 or 4, with the proviso that m+n is 2 or 3 or 4 or 5; R 1 and R 2 are either each independently a monovalent hydrocarbon radical having 1 to 12 carbon atoms, or together are a divalent hydrocarbon radical having 4 to 12 carbon atoms which is part of an optionally substituted carbocyclic ring having 5 to 8 carbon atoms; R 3 is a hydrogen atom or an alkyl group or an arylalkyl group or an alkoxycarbonyl group; R 4 and R 5 are either each independently a monovalent aliphatic, cycloaliphatic or arylaliphatic radical which has 1 to 20 carbon atoms and is free of hydroxyl groups and optionally contains heteroatoms in the form of ether oxygen or tertiary amine nitrogen, each independently a monovalent aliphatic, cycloaliphatic or arylaliphatic radical which has 1 to 20 carbon atoms and is free of hydroxyl groups and optionally contains heteroatoms in the form of ether oxygen or tertiary amine nitrogen, or together are a divalent aliphatic radical which has 3 to 20 carbon atoms and is part of an optionally substituted heterocyclic ring having 5 to 8 ring atoms, this ring being free of hydroxyl groups and, as well as the nitrogen atom, optionally containing further heteroatoms in the form of ether oxygen or tertiary amine nitrogen; X is O or S or N-R 6 or N-R 7, where R 6 is either a monovalent hydrocarbon radical which has 1 to 20 carbon atoms and optionally has at least one carboxylic ester, nitrile, nitro, phosphonic ester, sulfone or sulfonic ester group, or a substituent of the formula where p is 0 or an integer from 1 to 10 000, and B is a (p+1)-valent hydrocarbon radical which optionally contains ether oxygen, tertiary amine nitrogen, hydroxyl groups, secondary amino groups or mercapto groups; and either a monovalent hydrocarbon radical which has 1 to 20 carbon atoms and optionally has at least one carboxylic ester, nitrile, nitro, phosphonic ester, sulfone or sulfonic ester group, or a substituent of the formula p is 0 or an integer from 1 to 10 000, and B is a (p+1)-valent hydrocarbon radical which optionally contains ether oxygen, tertiary amine nitrogen, hydroxyl groups, secondary amino groups or mercapto groups; and R 7 together with A is an (n+2)-valent hydrocarbon radical which has 3 to 20 carbon atoms and optionally contains at least one heteroatom; wherein the aldimine of the formula is nt one of the following compounds: and L-H = and