Polyisocyanate/polyamine mixtures and their use for the production of polyurea coatings

A polyurea coating prepared from a coating composition which is free from polyols and comprises

• a) a polyisocyanate component,
• b) an aldimine corresponding to the formula
• X.sub.1 -[N.dbd.CHCH(R.sub.1)(R.sub.2)].sub.n
• and
• c) a compound containing aspartate groups and corresponding to the formula ##STR4## wherein X.sub.1 and X.sub.2 may be identical or different and represent 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,
• 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,
• 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
• n represents an integer with a value of at least 2,
• wherein components a), b) and c) are present in an amount sufficient to provide an equivalent ratio of isocyanate groups to aldimine groups and aspartate groups of 0.5:1 to 20:1 and wherein component c) is present in an amount sufficient to form a clear solution within 60 minutes of mixing components a), b) and c) at ambient temperature, provided that the amount of component c) is at least 5% by weight, based on the weight of components b) and c).

A coating composition which is free from polyols and comprises

• a) a polyisocyanate component,
• b) an aldimine corresponding to the formula:
• X.sub.1 -[N.dbd.CHCH(R.sub.1)(R.sub.2)].sub.n
• and
• c) a compound containing aspartate groups and corresponding to the formula ##STR5## wherein X.sub.1 and X.sub.2 may be identical or different and represent 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 hydrocarbon radicals containing 1 to 6 carbon atoms,
• R.sub.3 and R.sub.4 represent a methyl or ethyl group,
• R.sub.5 and R.sub.6 represent hydrogen and
• n is 2,
• wherein components a), b) and c) are present in an amount sufficient to provide an equivalent ratio of isocyanate groups to aldimine groups and aspartate groups of 0.5:1 to 20:1 and wherein component c) is present in an amount sufficient to form a clear solution within 60 minutes of mixing components a), b) and c), provided that the amount of component c) is at least 5% by weight, based on the weight of components b) and c).