Aldimine of the formula where R 1 and R 2 are either each independently a monovalent hydrocarbon radical having 1 to 12 carbon atoms, or together a divalent hydrocarbon radical which has 4 to 12 carbon atoms and is part of an optionally substituted carbocyclic ring having 5 to 8, preferably 6, carbon atoms; R 3 is a hydrogen atom or an alkyl or arylalkyl group, especially having 1 to 12 carbon atoms; R 4 is either a hydrocarbon radical which has 1 to 30 carbon atoms and optionally has ether oxygen atoms, or a radical where R 5 is a hydrogen atom or is a hydrocarbon radical having 1 to 5 carbon atoms; A is either an (m+y)-valent hydrocarbon radical which has 2 to 20 carbon atoms and optionally has heteroatoms, or, if y is 1 and X is N-R 7, together with R 7, an (m+2)-valent hydrocarbon radical which has 3 to 20 carbon atoms and optionally contains at least one heteroatom, especially 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 heteroatoms, especially in the form of ether oxygen or tertiary amine nitrogen, and optionally active hydrogen in the form of hydroxyl groups, secondary amino groups or mercapto groups, and R 7 together with A is an (m+2)-valent hydrocarbon radical which has 3 to 20 carbon atoms and optionally contains at least one heteroatom, especially in the form of ether oxygen or tertiary amine nitrogen; and m is 1 or 2 or 3 or 4, and y is 1 or 2 or 3 or 4. R 1 and R 2 are either each independently a monovalent hydrocarbon radical having 1 to 12 carbon atoms, or together a divalent hydrocarbon radical which has 4 to 12 carbon atoms and is part of an optionally substituted carbocyclic ring having 5 to 8, preferably 6, carbon atoms; R 3 is a hydrogen atom or an alkyl or arylalkyl group, especially having 1 to 12 carbon atoms; R 4 is either a hydrocarbon radical which has 1 to 30 carbon atoms and optionally has ether oxygen atoms, or a radical where R 5 is a hydrogen atom or is a hydrocarbon radical having 1 to 5 carbon atoms; A is either an (m+y)-valent hydrocarbon radical which has 2 to 20 carbon atoms and optionally has heteroatoms, or, if y is 1 and X is N-R 7, together with R 7, an (m+2)-valent hydrocarbon radical which has 3 to 20 carbon atoms and optionally contains at least one heteroatom, especially 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 heteroatoms, especially in the form of ether oxygen or tertiary amine nitrogen, and optionally active hydrogen in the form of hydroxyl groups, secondary amino groups or mercapto groups, and R 7 together with A is an (m+2)-valent hydrocarbon radical which has 3 to 20 carbon atoms and optionally contains at least one heteroatom, especially in the form of ether oxygen or tertiary amine nitrogen; and 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 heteroatoms, especially in the form of ether oxygen or tertiary amine nitrogen, and optionally active hydrogen in the form of hydroxyl groups, secondary amino groups or mercapto groups, and p is 0 or an integer from 1 to 10 000, and B is a (p+1)-valent hydrocarbon radical which optionally contains heteroatoms, especially in the form of ether oxygen or tertiary amine nitrogen, and optionally active hydrogen in the form of hydroxyl groups, secondary amino groups or mercapto groups, and R 7 together with A is an (m+2)-valent hydrocarbon radical which has 3 to 20 carbon atoms and optionally contains at least one heteroatom, especially in the form of ether oxygen or tertiary amine nitrogen; and m is 1 or 2 or 3 or 4, and y is 1 or 2 or 3 or 4.