Two component powder coating composition with separated catalyst system

A two component powder coating composition AB comprising paint component A and paint component B, wherein the powder coating composition AB comprises

• a crosslinkable composition, formed by a crosslinkable donor component (i) and a crosslinkable acceptor component (ii) that are crosslinkable by a Real Michael Addition (RMA) reaction, wherein
• the donor component (i) has at least 2 acidic C—H donor groups in activated methylene or methine, and
• the acceptor component (ii) has at least 2 activated unsaturated acceptor groups C═C, which react with donor component (i) by Real Michael Addition (RMA) reaction via a catalyst system,
• the catalyst system comprising a catalyst precursor (P) and a catalyst activator (C), which are separated so that
• paint component A comprises the catalyst precursor (P);
• paint component B comprises the catalyst activator (C);
• wherein the catalyst precursor (P) is a weak base with a pKa of its protonated form of more than 2 units lower than that of the activated C—H groups in donor component (i);
• and the catalyst activator (C) can react with (P) at curing temperature Tcur, producing a strong base (CP);
• optionally a non-RMA reactive component (iii) different from the donor component (i), the acceptor component (ii), the catalyst precursor (P) and the catalyst activator (C), wherein the coating composition AB comprises a crystalline component CC, that is present in an amount from 1 to 50 wt %, preferably 2 to 40 wt % and more preferably from 4 to 30 wt % in view of the total weight of the catalyst system, the crosslinkable composition and if present the non-RMA reactive component (iii);
• whereby at least part of the donor component (i) and/or acceptor component (ii) and/or the non-RMA reactive component (iii) is the crystalline component CC;
• and
• wherein both paint components A and B comprise the donor component (i) and the acceptor component (ii).