Two-component clear coat systems comprising polyaspartic acid ester

A process for producing a coating on a substrate comprising:

• i) applying a two-component coating composition to at least part of a substrate to be coated;
• and
• ii) curing the coating composition from step i),
• wherein the two-component coating composition comprises
• a) at least one polyaspartic ester-containing component A;
• b) at least one polyisocyanate component B;
• c) optionally one or more components C that are different from A and are reactive towards isocyanate groups;
• d) at least one water scavenger and/or hydrolysis stabilizer (component D1);
• and
• optionally other auxiliaries and additives (component D2),
• wherein component A comprises
• one or more polyaspartic esters of the general formula (I)
• in which
• X is an m-valent organic radical, optionally containing one or more heteroatoms, as can be obtained by removing the primary amino groups from a corresponding polyamine that has (cyclo) aliphatically or araliphatically attached primary amino groups and is in the molecular weight range from 60 to 6000 g/mol, and which may contain further functional groups that are reactive towards isocyanate groups and/or that are inert at temperatures of up to 100° C.,
• R1 and R2 are identical or different organic radicals each having 1 to 18 carbon atoms,
• m is an integer >1,
• and one or more polyaspartic esters having a primary amino group that are of the general formula (II)
• in which
• n is m-1,
• X and radicals R1 and R2 have the meanings defined above,
• wherein a proportion of compounds of the general formula (II) corresponds to ≥4% to ≤20% of a total area measured as area % in a gas chromatogram (GC), wherein the total area corresponds to a sum of the areas in the GC of compounds of the two general formulas (I) and (II) and is equal to 100% and wherein dialkyl fumarates are present in component A in amounts from ≥0.01% to ≤1.2% by weight based on a total weight of component A, and
• wherein the coating is a clear coat.