Why Is Aluminum Hydroxide the Go-To Flame Retardant?

Choosing a flame retardant is a critical decision. You need to balance performance, cost, and safety, and the wrong choice can lead to product failure or regulatory nightmares.

Aluminum hydroxide (ATH) is a top flame retardant because it is non-toxic, halogen-free, and highly effective. It works by releasing water vapor when heated, which cools the material, dilutes flammable gases, and suppresses smoke without creating toxic byproducts.

This simple, elegant mechanism is what makes ATH a cornerstone of modern fire safety. From my perspective managing production at our plant in Henan, I’ve seen its adoption grow dramatically across many industries. But to truly appreciate its value, you need to understand exactly how it works and what makes it different from other options.

Let’s break down the science behind it. Understanding these details will give you the confidence to select the perfect, safe, and effective flame retardant¹ for your products.

How does aluminum hydroxide stop fire?

You see "flame retardant" on a specification sheet, but what does that chemical actually do during a fire? It’s not magic, and without understanding the mechanism, you can’t be sure your material will perform as expected.

Aluminum hydroxide stops fire through endothermic decomposition. When heated above 200°C, it breaks down, absorbing a large amount of heat. It simultaneously releases harmless water vapor, which cools the material and displaces the oxygen needed for a fire to burn.

At our factory, we focus on perfecting the powder’s properties to maximize this three-in-one effect. It’s a powerful physical process, not a chemical one that creates toxins. Here’s how it works step-by-step when a plastic containing ATH is exposed to fire:

1. It Absorbs Heat: ATH’s primary function is to act as a heat sink. The chemical decomposition 2Al(OH)₃ → Al₂O₃ + 3H₂O is endothermic, meaning it requires a lot of energy. This process absorbs heat from the plastic, slowing its temperature rise and delaying ignition.
2. It Releases Water: For every kilogram of ATH, about 346 grams of water are bound within its crystal structure. During a fire, this is released as water vapor. This vapor dilutes the flammable gases that the decomposing plastic gives off, pushing them below the flammability limit.
3. It Forms a Protective Layer: After all the water is gone, what’s left is a layer of aluminum oxide (Al₂O₃), a hard, heat-resistant ceramic. This char layer acts as an insulating barrier on the plastic’s surface, shielding it from external heat and preventing oxygen from reaching the fuel source.

This multi-faceted approach is what makes ATH so reliable and effective.

What makes ATH better than other flame retardants?

The market is filled with different flame retardant chemicals. Choosing an older, cheaper option like a halogenated compound can introduce even bigger problems, like toxic smoke and environmental non-compliance, which can be devastating for a brand.

Compared to traditional halogenated flame retardants, aluminum hydroxide is superior because it’s non-toxic and environmentally friendly. It does not release corrosive or hazardous gases like dioxins during a fire. It is also an excellent smoke suppressant, a critical safety advantage.

This distinction is something I emphasize to all my customers, including buyers like Mr. Park who are focused on quality and safety. The move away from halogenated PBDs and PBDEs isn’t just a trend; it’s a global regulatory shift² driven by serious safety concerns. Here’s a direct comparison:

For any company looking to create a product that is safe for consumers and compliant with international standards like RoHS in Europe, ATH is the obvious choice. The fact that it reduces smoke density is a lifesaving benefit, giving people more time to evacuate during a fire. This is a powerful selling point that goes beyond the data sheet.

Are there different types of ATH for different applications?

You’ve decided you need aluminum hydroxide, but which one is right for your product? Using a generic, all-purpose grade for a specialized application can ruin your product’s strength, flexibility, or surface finish, wasting time and money.

Yes, there are many grades of aluminum hydroxide, which are defined by their particle size, purity, and surface treatment. Coarser grades are economical fillers, while fine, surface-treated grades are essential for high-performance applications like wire sheathing or thin plastic films.

As a manufacturer, this is where our expertise truly shines. We don’t just make one type of ATH. We engineer specific grades to solve specific customer problems. Getting this right is crucial for success.

Here’s what a buyer needs to consider:

• Particle Size (D50): This is the most important factor. A finer particle size⁴ (e.g., 1.5 microns) is needed for applications where the plastic is thin or needs good flexibility and a smooth surface, like in wire and cable insulation. A coarser particle (e.g., 15 microns) is more cost-effective and works well in thicker, rigid applications like cast polymers or electrical housing where surface finish is less critical.
• Purity and Whiteness: For products like solid surface countertops or brightly colored plastics, high purity and brilliant whiteness are essential to achieve the desired aesthetic.Contaminants can cause discoloration.
• Surface Treatment: This is a high-value feature. We coat the ATH particles with agents like silanes or stearic acids. This coating acts as a "bridge," helping the inorganic filler bond better with the organic plastic resin. The result is dramatically improved mechanical properties, like tensile strength and elongation, preventing the plastic from becoming brittle.

Conclusion

Aluminum hydroxide is a premier flame retardant because its three-in-one a mechanism is both highly effective and environmentally safe. With grades tailored for any application, it offers a reliable, future-proof solution.