What Is the Optimal Particle Size Range for Aluminum Hydroxide Used in Artificial Stone?

Aluminum hydroxide (ATH), as the core flame retardant filler and reinforcing component of artificial stones (especially quartz and solid surface materials), has a decisive impact on material properties due to its particle size distribution.

Ⅰ. The mechanism of action of aluminum hydroxide in artificial stone

·Flame retardant effect: Heat decomposition (starting temperature about 180-200 ℃) absorbs heat, releases water vapor to dilute oxygen concentration

·Packing function: Improve hardness, wear resistance, and dimensional stability

·Cost optimization: Partial substitution of resin to reduce raw material costs

·Aesthetic adjustment: affects the transparency and texture performance of the board

Ⅱ. ATH for artificial stone: Why is particle size so critical?

The ATH refractive index is highly matched with the resin, giving artificial stones a jade like texture, transparency, and flame retardant and smoke suppressing properties. Uncontrolled particle size can directly lead to:

-Coarse: rough surface, easy color bleeding, decreased strength, difficult polishing, and prone to edge breakage

-Too fine: high system viscosity, difficult mixing, decreased filling amount, increased cost, easy cracking

-Wide distribution: uneven appearance, stripes, pinholes, and fluctuations in mechanical properties

The optimal particle size is essentially the balance point between appearance, strength, processing, and cost, and it is also the watershed between high-end artificial stone and ordinary board.

Ⅲ. Global Best Particle Size Range (D50, Median Particle Size)

Based on the standards of high-end countertops, bathrooms, and decorative panels in Europe, America, the Middle East, and Southeast Asia, the golden particle size range of ATH for artificial stone is as follows:

1. Universal flagship level (preferred by global mainstream)

D50：8–15 μm

-Adaptation: Acrylic artificial stone, polyester solid surface material, kitchen countertop, bathroom cabinet, wall panel

-Advantages: delicate texture, uniform transparency, excellent strength, easy polishing, good stain resistance

-Process: Moderate viscosity, high filling amount, stable curing, high mass production yield

-Conclusion: The universal optimal range for global exports is 8-15 μ m, which is the first choice

2. High end transparency/jade like feel (high-end and luxury level)

D50: 5-10 μ m (narrow distribution)

-Adaptation: High end bathroom, transparent board, minimalist countertop, medical beauty/hotel space

-Advantages: High glossiness, strong jade like texture, porcelain like surface, zero pores

-Key points: Cooperate with high whiteness, low oil absorption, surface modification to prevent agglomeration

-Conclusion: Pursuing ultimate texture and transparency, 5-10 μ m is the optimal size

3. High strength/large board/engineering board (preferred for commercial and tooling)

D50：15–25 μm

-Adaptation: large boards, window sills, countertops, outdoor decorations, engineering batch

-Advantages: stronger bending/impact resistance, low shrinkage rate, less likely to deform, high processing efficiency

-Conclusion: Strength is prioritized, mass production is stable, and 15-25 μ m is optimal

4. Special compound grade (commonly used in high-end formulas)

Composite of fine powder 5-15 μ m and coarse powder 50-90 μ m

-Logic: Fine powder filling, coarse powder skeleton, achieving the highest filling amount, lowest viscosity, and optimal cost

-Effect: Dense board surface, high strength, uniform texture, and better flame retardancy

-Conclusion: International manufacturers have formulated standards that balance performance and cost

Summary

Aluminum hydroxide used for artificial stone does not have a unique particle size, but has an optimal range:

-General export preferred: D50 8-15 μ m

-High end transparent preferred: D50 5-10 μ m

-Preferred for engineering large boards: D50 15-25 μ m

-Preferred compound for enhancing efficiency: 5-15 μ m+50-90 μ m compound

By selecting the right particle size, we can consistently produce globally competitive artificial stones with high texture, strength, yield, and premium.