Alumina Trihydrate FR Grade (Coarser)

This coarser alumina trihydrate (ATH) flame retardant grade features a median particle size of approximately 40–80 µm, designed specifically for applications where fast filler incorporation, minimal viscosity increase, and cost-effective bulk FR loading are the primary requirements over fine surface finish or high mechanical performance.

Coarser ATH allows faster wetting by resin systems due to its lower surface area, reducing the power and time required for mixing even at very high loadings (150–200 phr). This makes it the grade of choice for thick-section castings, artificial stone backing compounds, and bulk-filled resin systems where throughput and cost efficiency are paramount.

With its lower specific surface area (typically 0.5–1.5 m²/g), coarser ATH has a much lower viscosity impact per unit weight than fine grades, enabling formulators to achieve target FR performance at higher total loading without excessive viscosity penalty. However, at equivalent loading, coarser ATH provides somewhat lower mechanical properties than fine grades due to larger stress concentration sites. Typical applications include economical fire-resistant pultrusion compounds, thick cast artificial stone, and FR compound backing layers where surface finish requirements are relaxed.