Powder coating composition

A powder coating composition comprising one or more crosslinkable components and a catalyst, wherein the one or more crosslinkable components are crosslinkable by Real Michael Addition (RMA) reaction, and the powder coating composition comprises

• a. a crosslinkable component A having at least 2 acidic C—H donor groups in activated methylene or methine,
• b. a crosslinkable component B having at least 2 activated unsaturated acceptor groups C═C, which react with component A by Real Michael Addition (RMA) to form a crosslinked network,
• c. a latent catalyst system C comprising a strong base or a precursor of a strong base to catalyze the RMA crosslinking reaction with a delay at a curing temperature of at least 80° C. and below 200° C.,
• wherein the catalyst system C is a latent catalyst system LCC having chemical latency comprising components that react at the curing temperature to initiate the reaction between crosslinkable components A and B with a delay, said latent catalytic system LCC comprising
• embodiment LCC2:
• a) a weak base C2 that is a Michael addition donor S2, and
• b) an activator C1 that is a Michael acceptor S1 comprising an activated unsaturated group C═C reactive with S2 at the curing temperature,
• c) optionally further comprising an acid C3 being an acid S3 of which the corresponding base also is a Michael addition donor, or a protonated S2,
• wherein
• in case S1 is an acrylate, S2 has a pKa of the conjugated acid below 8, wherein pKa is defined as the value in an aqueous environment, and
• in case S1 is a methacrylate, fumarate, itaconate or maleate, S2 has a pKa of the conjugated acid below 10.5, and
• wherein the powder coating composition has a curing profile, as determined by measuring the conversion of the unsaturated bonds C═C of component B as a function of time by FTIR, at a curing temperature chosen between 80, 90, 100 and 200, 150, 135 or 120° C., wherein the ratio of the time to go from 20% to 60% C═C conversion to the time to reach 20% conversion is less than 1, with the time to reach 60% conversion being less than 30, and with the time to reach 20% conversion at 100° C. is at least 1 minute.