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ATH (aluminium trihydrate, chemical formula Al(OH)3) is a side stream of aluminium production, characterised by:
- High purity
- High whiteness
- Relatively low density of 2.4g/cm3 compared to other mineral fillers, which are typically at 2.7g/cm3
- Medium Mohs hardness of 3
- Decomposition around 180°C, releasing water.
Non-flame retardant applications
[g/ 100 g]
Flame retardant applications
[g /100 g]
Production locations Portaflame SG, Portafill A
Portafill A and Portaflame SG are the brand names for Sibelco’s ATH products:
- Portafill A is used in applications, where flame retardancy is not required, such as powder coating applications.
- Portaflame SG is used in flame retardant applications, such as ETICS (External Thermal Insulation Composite Systems)/EIFS (External Insulation Finishing Systems).
- Dirt pick-up resistance: the presence of ATH improves the coating’s resistance to dirt (from the atmosphere, for example).
- Ease of tinting: due to the combination of refractive index, brightness and colour, paints with ATH provide excellent reproducible colour results when working with tinting systems.
- Sandability: due to its fairly low hardness of 3 on Mohs scale, a coating with ATH is still relatively easy to sand, making it perfect for achieving a high gloss finish.
- Chemical resistance: due to its inert nature, ATH provides good chemical resistance compared to conventional fillers.
- Abrasion resistance: due to its hardness of 3 on Mohs scale, ATH will increase the coating’s resistance to wear.
- Clarity: due to its fairly low refractive index, ATH becomes transparent when combined with certain binder systems.
- UV-curing compatibility: being transparent for UV radiation, ATH does not block the curing mechanism.
- Gloss control: with the availability of ultrafine ground ATH (Portafill A7) and a product with an optimised particle size distribution (Portafill A25/10), it is possible to apply coatings with a broad range of gloss levels.
- Increasing extruder output: the optimised particle size distribution of Portafill A25/10 provides better free-flowing properties. As a result, the material is easier to dose into the extruder, allowing the residence time inside the extruder to be optimised.
- UV resistance: being insensitive to UV radiation, ATH will reduce the coating’s degradation.
- Water spotting resistance: powder coatings formulated with ATH show less tendency for water spotting than similar coatings formulated with barium sulphate.
- Stain blocking and stain resistance: ATH acts as a supporting mineral filler in stain blocking and stain resistant coatings.