Production process of powder coatings
The different dry raw materials (resin, hardener, pigment, additive, filler) are weighed in exact quantity and put in a container. This container will be tumbled or mixed during a determined time so that the raw materials are well mixed. A rather homogeneous distribution is obtained. The container is brought to the extruder, after control on homogeneity.
In the extruder, ingredients are warmed up to a sort of paste, mixed and kneaded. On molecular scale resin and hardener will be mixed together. The pigments and additives will be dispersed in the weak mass.
The paste, leaving the extruder is immediately flattened between two cylinders and cooled down on a conveyer. At the end of the cooling conveyer, the continuous powder plate is broken down into little pieces (named “chips”) that will be caught up in containers.
The containers with “chips” go to the grinding machine. The chips are ground to a determined standard particle size by means of a centrifugal separator. Too small pieces are removed. Too big pieces finish in the grinding machine till they attain an acquired particle size.
When an optimum particle size is obtained, powder is placed in boxes (5,10,15,20,25 kg) or big-bags (about 450kg).