Process for the manufacture of semi-crystalline powder coating

摘要

Manufacturing a powder coating composition involves: (i) melting a powder coating composition containing optionally saturated semi-crystalline polyester(s) or polyesterurethane(s) as a binder and other constituents for manufacturing powder coatings; atomizing the melt into droplets using acoustic forces of ultrasonic standing wave field; and allowing atomized droplets to cool to form solid free flowing semi-crystalline powder particles. Manufacturing a powder coating composition involves: (1) melting a powder coating composition containing at least one optionally saturated semi-crystalline polyester or polyesterurethane as a binder (a), optionally at least one optionally saturated compound (b) different from (a); at least one of which is reactable with the other resins present in (a), and other constituents for manufacturing powder coatings (c); (2) atomizing the resulting melt into droplets using acoustic forces of an ultrasonic standing wave field, made up of ultrasonic waves generated by two sonotrodes, facing each other and oscillating with the same amplitude at 60 - 140 mu m at a substantial identical frequency of at least 10 (preferably 20 - 50) kHz; and (3) allowing the atomized droplets to cool to form solid free flowing semi-crystalline powder particles. Independent claims are included for the following: (a) a clear lacquer powder composition (C1) comprising the powder coating composition and pigments, dyes and fillers; and (b) coating a metallic or non-metallic substrate involving: applying (C1) to the substrate by electrostatic or friction charging spray gun or fluidized bed; and curing the powder by heat and/or radiation.