Aluminum hydroxide (ATH) is a white amorphous powder. It is an amphoteric hydroxide. Ultrafine aluminum hydroxide is stable at room temperature. It does not produce secondary pollution during combustion. It has high whiteness and excellent color properties.
Nano-sized ATH increases the limiting oxygen index of flame-retardant polymers. It improves flame retardancy. It enhances surface smoothness, mechanical strength, and electrical properties. It improves resistance to leakage current, arc resistance, and wear resistance.
ATH works well when compounded with other flame retardants. It is synergistic, non-volatile, non-toxic, and non-corrosive. It is abundant and low-cost. Therefore, it is widely used as an inorganic flame retardant.
Advantages of Aluminum Hydroxide Flame Retardants
Ultrafine aluminum hydroxide remains stable in its physical and kimia properties at room temperature, produces no secondary pollution during combustion, and offers high whiteness with excellent color performance. Nano-sized aluminum hydroxide not only increases the limiting oxygen index of polymers, improving flame retardancy, but also enhances polymer surface smoothness, mechanical, and electrical performance. It strengthens resistance to leakage current, arc resistance, and wear resistance. Moreover, aluminum hydroxide shows ideal synergistic effects when used in combination with other flame retardants. It is non-volatile, non-toxic, non-corrosive, abundant, and cost-effective, making it a widely applied inorganic flame retardant.
Preparation Methods of Ultrafine Aluminum Hydroxide Micro-Powders
Physical Method
The general preparation of aluminum hydroxide powder can be achieved through both physical and chemical methods. The physical method involves crushing ATH blocks or granules using kilang bolas, vibration mills, or kilang jets. The material is broken into finer particles by deformation and fracture, followed by surface modification to improve performance if needed. This process usually uses coarse aluminum hydroxide particles from alumina plants as raw material, which are then processed through pengilangan jet dispersion and klasifikasi udara to obtain ultrafine ATH. The physical method features low cost, high yield, and simple processing. However, the saiz Zarah distribution is relatively wide (typically 5–15 μm), particle morphology is irregular, and whiteness and purity depend on the raw ATH material. Thus, it is suitable for applications where requirements for purity, particle size, and morphology are not very strict.
Chemical Methods
- Seeding Method
The seeding method involves adding ultrafine ATH seeds into a prepared sodium aluminate solution to obtain finer and purer ATH powders. The quality of the seed crystals is a key factor influencing particle size distribution. - Sol–Gel Method
This method hydrolyzes aluminum compounds under controlled bath temperature, stirring speed, and pH conditions to form an ATH colloid, which is then converted into a gel. After drying and grinding, ultrafine ATH powders with smaller particle size are obtained. - Precipitation Method
Precipitation methods include direct precipitation dan homogeneous precipitation. Direct precipitation involves adding a precipitant into an aluminate solution under controlled conditions to produce high-purity ultrafine ATH. The mixing efficiency of the precipitant and solution is critical to the final product’s properties. Homogeneous precipitation differs from direct precipitation in that the precipitation rate is more gradual, leading to different powder characteristics. - Hydrothermal Method
In hydrothermal synthesis, raw materials react in an organic solvent medium at high temperature and pressure within a sealed reaction vessel to produce ATH powders. - Carbonation Method
The carbonation method introduces CO₂ into a sodium aluminate solution. By controlling reaction conditions, ultrafine ATH can be produced.
Bedak Epik
As a key flame retardant, ultrafine aluminum hydroxide is increasingly demanded in plastics, rubber, cables, coatings, and other industries. Achieving stable quality and ultrafine particle sizes requires advanced powder processing technology. Epic Powder, with over 20 years of experience in ultrafine grinding and classification, provides customized solutions using ball mills, jet mills, air classifiers, and surface modification equipment. With reliable technology and professional expertise, Epic Powder ensures the efficient and precise production of high-performance ATH micro-powders, helping customers maximize product value in the competitive flame-retardant market.