Non-etherified reaction product of a cyclic urea and a multifunctional aldehyde

The invention relates to a coating composition comprising a reaction product UA of at least one multifunctional aldehyde A with at least one cyclic urea U， and a crosslinkable resin having at least one kind of functional groups selected from the group consisting of hydroxyl functional groups， acid functional groups， amide functional groups， amino functional groups， imino functional groups， mercaptan functional groups， phosphine functional groups， and carbamate functional groups， characterised in that the degree of etherification， measured as the ratio ??(13 O—R)/??(U) of the amount of substance n(—O—R) of alkoxy groups as substituents of the aldehyde carbon atoms of the multifunctional aldehyde chemically bound in the reaction product UA to the amount of substance ??(U) of cyclic urea U chemically bound in the reaction products， is less than 0.01 mol/mol， and to a process for the preparation of the reaction product UA.