Applying microwave energy to fabricate powder coatings with strong and stable metal shine

Metallic pigmented powder coating, composed of coating powders and metallic pigments, has been drawing more attention and occupying more market share with more stringent environmental pressure on traditional metallic solvent paint. To overcome the shortcomings of the thermal bonding method that aims at bonding the two incompatible ingredients, a self-designed microwave bonding device was first developed and tested in the present work. Taking advantage of the heating-selectivity of the microwave, a lower bonding temperature was obtained when compared to the thermal bonding method. Also, through the analysis of bonding rate and color difference, a higher bonding quality and enhanced color stability were found. More bondings between coating particles and Al flakes were clearly observed by SEM and EDS in the microwave-bonded samples. The microwave bonding is proved to be a feasible and efficient method and thus the bonding device has great potential to replace the present bonding machine.