Every thermoset powder pairs a base resin with a crosslinker sized to its reactive groups: TGIC or HAA for carboxyl polyesters, blocked isocyanates for hydroxyl polyesters, and amines, anhydrides or phenolics for epoxies. The choice sets the cure temperature, how much overbake the film tolerates, whether anything gasses off and how the film weathers. Formulators also add catalysts to speed or slow that reaction.
Same resin, different crosslinker, so the new batch wants another 20 degrees to cure.
Also heard as
- curing agent
- hardener
Related terms
Thermoset powder
Coating powder that melts, flows and then chemically crosslinks in the oven, so it cannot be remelted.
TGIC
Triglycidyl isocyanurate, the classic crosslinker that cures carboxyl polyesters into weather-resistant films.
HAA
Hydroxyalkylamide, the TGIC-free crosslinker used to cure carboxyl polyester powders.
Gel time
How many seconds a powder takes at a set temperature to go from melted to a rubbery gel that no longer flows.