Process for the production of compounds containing aspartate and aldimine groups

A process for preparing a compound containing aspartate and aldimine groups corresponding to the formula ##STR5## which comprises a) reacting 50 to 95 mole % of the primary amino groups present in a polyamine containing 2 to 6 primary amino groups with a maleic or fumaric acid ester corresponding to the formula

• R.sub.3 OOC--CR.sub.5 =CR.sub.6 --COOR.sub.4
• until at least 95 mole percent of the unsaturated groups have reacted and
• b) subsequently reacting the remaining primary amino groups with an aldehyde corresponding to the formula
• O=CHCH(R.sub.1)(R.sub.2)
• wherein
• X represents an organic group which has a valency of n and is inert towards isocyanate groups at a temperature of 100.degree. C. or less,
• R.sub.1 and R.sub.2 may be the same or different and represent optionally substituted hydrocarbon radicals, or R.sub.1 and R.sub.2 together with the .beta.-carbon atom form a cycloaliphatic or heterocyclic ring and
• R.sub.3 and R.sub.4 may be identical or different and represent organic groups which are inert towards isocyanate groups at a temperature of 100.degree. C. or less and
• R.sub.5 and R.sub.6 may be identical or different and represent hydrogen or organic groups which are inert towards isocyanate groups at a temperature of 100.degree. C. or less and
• a and b represent integers having a value of 1 to 5, provided that the sum of a and b is 2 to 6.