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    HomeProductsBasic & Fine ChemicalsInorganic ChemicalsAluminum Hydroxide CAS 21645-51-2
    • Aluminum Hydroxide CAS 21645-51-2

    Aluminum Hydroxide CAS 21645-51-2

    Aluminum Hydroxide (CAS 21645-51-2) is a functional inorganic filler serving as a halogen-free flame retardant and smoke suppressant in polymer composites and solid surface materials. Chemically identified as Alumina trihydrate or ATH, this white powder acts effectively to release chemically bound water molecules at elevated temperatures, thereby mitigating combustion in cable sheathing and engineering plastics. As a high-purity Aluminum trihydroxide, it ensures high whiteness and optimal dispersion within thermoset resin systems and construction coatings. We ensure bulk supply capabilities for this material, providing access to competitive factory pricing and customized specifications to meet specific particle size distribution needs. Full technical documentation, including MSDS, TDS, COA, is available to support compliance and safety protocols.

    • CAS: 21645-51-2
    • Synonyms: Alumina trihydrate, ATH, Hydrated alumina, Aluminum trihydroxide
    • Einecs: 244-492-7
    • Molecular Formula: Al(OH)3
    • Grade: Flame Retardant Grade (ATH), Industrial Grade, High Whiteness Filler Grade, Ultra-fine Grade
    • Package: 25kg/bag (paper-plastic composite), 500kg/1000kg Jumbo bags, or customized neutral packaging.
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    Product Description

    Aluminum Hydroxide (𝐴𝑙(𝑂𝐻)3) from Industrochem is a non-toxic, halogen-free, and environmentally friendly inorganic flame retardant. Our powder is produced through the Bayer process, followed by specialized grinding and classification to achieve specific surface areas and particle sizes.
    The primary advantage of our ATH powder lies in its thermal decomposition: at approximately 200°C, it undergoes an endothermic reaction, releasing water vapor to dilute combustible gases and forming a protective alumina layer on the material surface. This “three-in-one” function—flame retardancy, smoke suppression, and filling—makes it the most cost-effective solution for cables, rubber, and thermoset plastics. Additionally, our high-whiteness grades serve as premium fillers for artificial marble and solid surfaces, providing excellent translucency and mechanical strength.

    1 Physicochemical Properties
    2 Applications
    3 Storage Conditions
    4 Safety Precautions

    Physicochemical Properties

    PropertyStandard Grade (Typical)High Whiteness GradeUltra-Fine Grade
    Al(OH)3 Content≥ 99.6%≥ 99.8%≥ 99.9%
    Al2O3 Content≥ 65.1%≥ 65.2%≥ 65.3%
    Whiteness≥ 93%≥ 97%≥ 98%
    Moisture (H2O)≤ 0.2%≤ 0.15%≤ 0.2%
    SiO2 Content≤ 0.01%≤ 0.005%≤ 0.005%
    Fe2O3 Content≤ 0.01%≤ 0.008%≤ 0.002%
    Na2O Content≤ 0.2%≤ 0.15%≤ 0.1%
    Particle Size (D50)10 – 15 μm5 – 8 μm1 – 3 μm
    Oil Absorption22 – 26 ml/100g28 – 35 ml/100g40 – 50 ml/100g
    pH Value8.0 – 10.08.0 – 9.58.5 – 10.0

    Applications

    1. Flame Retardant Filler: The most widely used halogen-free flame retardant for PVC, PE, EVA, and epoxy resins. Ideal for wire and cable compounds, insulators, and conveyor belts.
    2. Artificial Marble & Solid Surfaces: High-whiteness ATH is the primary filler for acrylic and polyester resins, providing the “stone-like” appearance, fire resistance, and easy-to-clean properties.
    3. Glass & Ceramics: Used as a raw material to increase chemical resistance, thermal shock resistance, and mechanical strength in glass formulations and ceramic glazes.
    4. Paper Coating: Acts as a high-brightness pigment and flame-retardant coating in decorative and technical papers.
    5. Water Treatment: Serves as a raw material for the production of Polyaluminum Chloride (PAC) and Aluminum Sulfate coagulants.
    6. Catalyst Carrier: High-purity grades are used in the petrochemical industry as a substrate for various catalysts.

    Storage Conditions

    • Environment: Store in a cool, dry, and well-ventilated warehouse.
    • Moisture Control: Aluminum Hydroxide is prone to moisture absorption; ensure bags remain sealed. Do not store directly on concrete floors; use pallets.
    • Contamination Prevention: Keep away from strong acids and alkaline substances to maintain chemical purity.
    • Stacking: Limit stacking height to prevent caking of ultra-fine powders.

    Safety Precautions

    • Dust Protection: Although non-toxic, the powder is a nuisance dust. Wear an approved dust mask (N95/P2) and safety goggles during handling.
    • Skin Contact: May cause mild dryness or irritation. Wear protective gloves and wash hands after use.
    • Handling: Use local exhaust ventilation to minimize airborne dust concentrations.
    • Environmental: ATH is stable and non-hazardous to the environment, but large spills should be contained and vacuumed to prevent entering drainage systems.

    FAQ - Technical & Supply Chain

    • Q:

      What is the primary chemical function of Aluminum Hydroxide CAS 21645-51-2 in polymer matrices?

      A: Aluminum Hydroxide (CAS 21645-51-2), widely known as ATH, acts as an inorganic flame retardant filler that undergoes endothermic decomposition to release water vapor and dilute combustible gases.
    • Q:

      Can this ATH powder be utilized in the production of solid surface materials and artificial marble?

      A: Yes, this material is typically applied in solid surface manufacturing, providing high whiteness, translucency, and flame resistance essential for acrylic or polyester resin-based countertops.
    Documents

    Documents and Product Support

    For product review and sourcing evaluation, supporting documents can be coordinated according to the product type, inquiry stage, and order requirements.

    • COA for batch-based quality reference
    • TDS for key physical and chemical information
    • SDS / MSDS for handling, storage, and safety reference
    • Packing information for sample, trial, and bulk orders
    • Technical communication based on application and specification requirements
    Quotation

    Information to Confirm Before Quotation

    Clear sourcing information helps reduce specification mismatch and allows a more accurate quotation before sample or bulk order discussion.

    • Product name and CAS number
    • Application or intended end use
    • Required purity, grade, or specification
    • Sample quantity, trial order, or bulk demand
    • Preferred packing form or net weight
    • Destination country or port
    • Required documents or compliance expectations
    Storage & Handling

    Packaging, Storage, and Handling Notes

    Packaging form, storage conditions, shelf life, and shipment arrangements should be confirmed according to the product characteristics, package size, and destination requirements.

    Before order confirmation, buyers are advised to review the corresponding product documents and confirm whether any special storage, labeling, or handling requirements apply.

    Supply Support

    Sample, Bulk Order and Repeat Supply Support

    Support can be arranged for sample discussion, bulk supply planning, packaging confirmation, and routine sourcing communication based on the actual product and order requirements.

    For repeat-use formulations or long-term procurement plans, buyers may discuss specification consistency, packaging preferences, delivery expectations, and document coordination in advance.

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    Tags:

    Aluminum Compound Flame Retardant Additive Inorganic Hydroxide Mineral Filler

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