Powder coatings are applied as free-flowing, dry powder with no solvent or water present. This moisture needs to be removed during the drying/curing process to achieve this final coating.
Mineral fillers play an important role in powder coatings.
- They can be used to improve water spotting resistance on pre-coated steel profiles during transportation and storage when covered with a plastic sheet.
- As the majority of powder coatings are still sold by weight, mineral fillers with a high density are preferred.
- To have good abrasion resistance, minerals fillers with a high hardness up to 8.5 on Mohs scale can be used.
- Depending on the application, chemical resistance is important. This can be achieved by using inert mineral fillers, mineral fillers that can create a barrier inside the coating, and mineral fillers which act as a synergist when combined with typical anti-corrosive pigments, such as zinc phosphates.
- Mineral fillers play a role in achieving the required gloss level of the coating, being either high, neutral or low in gloss.
- For outdoor applications, UV resistance is important. The majority of the mineral fillers are not affected by UV radiation and therefore contribute to an improved performance in outdoor applications.
- Minerals fillers with good free-flowing properties are easier to dose in an extruder, allowing the residence time inside the extruder to be optimised, and therefore increasing output.