Study of the incorporation of smectite in powder coating

Abstract

The use of clays to formulate powder coating can improve physical properties, besides a final product with more sustainable characteristics due to the elimination of some additives, which may be substituted for the clay. We investigate the use of a modified smectite clay to formulate powder coating based on polyester resin. Four compositions of incorporated clay were evaluated (0, 4, 7, and 10 wt%). Powder coating were prepared in a twin-screw extruder at 105, °C, and characterized by XRD, FTIR and SEM. Tests of flexibility, adhesion and impact strength in accordance to ASTM standards were performed. Diffractograms of the samples showed the characteristic peak of the modified smectite in d(001), ~, 37°(2θ), indicating exfoliation of the clay. Micrographs by SEM showed the presence of lamellar structure for the clay-based powder coating. Mechanical assays were found for all analyzed coatings, indicating that sample containing 7% of clay presents the best performance.