<p>Aqueous coating composition comprising (1) at least one vinyl polymer having a Mw>=15 kDa and a Tg>=0° C. formed from (i) 0.1 to 20 wt % of vinyl monomer(s) containing acid functional groups and (ii) 0 to 0.49 wt % of vinyl monomer(s) containing a carbonyl functional group(s) and (2) 0.01 to 10 wt % of at least one polyhydrazine compound B where said composition provides a film coating of König hardness >=40 s.</p>
