Aluminium hydroxide (ATH), also known as aluminium trihydrate, is widely used as a halogen-free flame retardant in plastics, rubber, and wire and cable compounds. It can reduce flammability while offering smoke suppression and a relatively low environmental impact. Its performance, however, depends on factors such as particle size, loading level, compatibility with the polymer matrix, and processing conditions.

This guide explains how aluminium hydroxide works as a flame retardant, where it is commonly used, and what to consider when selecting an ATH grade. It also compares ATH with magnesium hydroxide (MDH) and introduces the relevant product specifications offered by KMT Industrial.

Table of Contents

  1. Introduction to Aluminium Hydroxide as a Flame Retardant
  2. What Is Aluminium Hydroxide (ATH)?
  3. How Does Aluminium Hydroxide Work as a Flame Retardant?
  4. Key Properties of Aluminium Hydroxide Flame Retardant
  5. Main Applications of ATH Flame Retardants
  6. Advantages and Limitations of Aluminium Hydroxide
  7. ATH vs. Magnesium Hydroxide: Key Differences
  8. Factors Affecting ATH Flame Retardant Performance
  9. KMT Industrial Aluminium Hydroxide Product
  10. How to Select the Right Aluminium Hydroxide Grade
  11. Conclusion and Recommendations

1. Introduction to Aluminium Hydroxide as a Flame Retardant

Aluminium hydroxide flame retardant, commonly known as ATH, is used in applications such as cable insulation and jacketing, rubber products, thermoset composites, selected thermoplastics, sealants, and building materials. Its suitability depends on the polymer matrix, processing temperature, required fire classification, filler loading, and final-product performance criteria.

KMT Industrial's aluminium hydroxide product page provides information about its ATH offering and product specifications. This guide explains how aluminium hydroxide functions as a flame retardant, where it is used, which properties matter during formulation, and how to evaluate a suitable grade for industrial applications.

Key Industry Considerations

  • ATH is an inorganic, halogen-free flame-retardant additive.
  • Its endothermic decomposition absorbs heat and releases water vapor.
  • Particle size, particle-size distribution, and surface treatment influence dispersion and compound properties.
  • ATH has a relatively low decomposition temperature compared with some other inorganic flame retardants, so processing temperature must be considered.
  • Finished-product fire performance depends on the complete formulation and applicable test method, not ATH alone.

2. What Is Aluminium Hydroxide (ATH)?

Aluminium hydroxide is an inorganic compound with the chemical formula Al(OH)₃. It is also commonly called aluminum hydroxide or aluminium trihydrate (ATH) in industrial and flame-retardant applications. The material is generally supplied as a white powder and can be incorporated into selected polymer systems as a functional filler and flame-retardant additive.

When heated to its decomposition range, ATH absorbs thermal energy and releases chemically bound water. This process helps cool the surrounding material and can dilute combustible gases close to the burning surface. The remaining aluminium oxide-containing residue can also contribute to a protective solid layer, depending on the formulation and burning conditions.

ATH is particularly relevant to applications that can accommodate its thermal decomposition characteristics. It is often used in unsaturated polyester and other thermoset composites, rubber products, selected thermoplastics, wire and cable compounds, and construction materials. The grade must be matched to the processing window and performance requirements of the intended application.

Unlike a reactive flame-retardant ingredient that chemically modifies the polymer, ATH generally functions as an additive dispersed within the material. Its effectiveness therefore depends on factors such as filler loading, particle distribution, dispersion quality, polymer compatibility, and the presence of other formulation ingredients.

2.1 Chemical and Physical Characteristics

The following table summarizes general reference characteristics of aluminium hydroxide. These are material-level descriptions, not a substitute for the technical data sheet of a specific commercial grade.

Property General Description Relevance to Flame-Retardant Applications
Chemical Formula Al(OH)₃ Identifies the inorganic hydroxide additive.
Molecular Weight Approximately 78.00 g/mol Useful for chemical and formulation calculations.
Appearance Typically a white powder Whiteness may matter in light-colored finished products.
Thermal Decomposition Typically occurs within an approximate range of 180–220°C, depending on material and test conditions Sets an important consideration for processing temperature and residence time.
Water Release Theoretical chemically bound water content is approximately 34.6% by mass Water vapor contributes to cooling and dilution of combustible gases.
Residue Aluminium oxide-containing solid residue May contribute to a protective barrier during combustion.
Solubility Low solubility in water under ordinary conditions Relevant to material handling and formulation design.

For procurement and production approval, request the current technical data sheet (TDS), safety data sheet (SDS), and batch-specific certificate of analysis (COA). Confirm the test methods and acceptance limits used for each specification before comparing products from different suppliers.

2.2 Why Is ATH Used in Polymer Formulations?

ATH combines several functions that can be useful in industrial compounds. It can act as a mineral filler while also contributing to flame retardancy through its endothermic decomposition. This makes it a candidate for formulations in which the manufacturer wants to combine filler performance, fire-related properties, and a halogen-free additive system.

  • Flame-retardant contribution: Absorbs heat and releases water vapor when it decomposes.
  • Halogen-free composition: ATH itself does not contain bromine or chlorine in its chemical formula.
  • Filler functionality: Can contribute to the physical properties and formulation economics of selected compounds.
  • Appearance: Its white color can be suitable for applications where a light-colored filler is preferred.
  • Formulation flexibility: Can be used with compatible polymers and, where appropriate, combined with other flame-retardant additives.

However, a formulation containing ATH is not automatically halogen-free, low-smoke, or compliant with a particular fire standard. These descriptions must be established through the complete formulation and finished-product testing.

Aluminium hydroxide ATH powder used as a halogen-free flame-retardant additive

3. How Does Aluminium Hydroxide Work as a Flame Retardant?

Aluminium hydroxide contributes to flame retardancy primarily through endothermic decomposition, water-vapor release, and the formation of an aluminium oxide-containing residue. These mechanisms can help reduce the temperature of the material exposed to fire and influence the transfer of heat and combustible gases. Their effectiveness depends on the polymer matrix, ATH concentration, particle dispersion, and the conditions of the fire test.

ATH is therefore not a universal fire-protection solution. It is a formulation component whose performance must be evaluated alongside the resin, other additives, processing conditions, and the requirements of the final product.

3.1 Endothermic Decomposition and Heat Absorption

Heat Absorption During Decomposition

When aluminium hydroxide is heated sufficiently, it decomposes and absorbs energy from its surroundings. A simplified representation of the reaction is:

2Al(OH)₃ + Heat → Al₂O₃ + 3H₂O ↑

The reaction absorbs heat while releasing water vapor. This can slow the temperature rise of the polymer and reduce the energy available to support combustion. The actual decomposition behavior depends on particle characteristics, heating rate, and test conditions.

The heat-absorption effect is one reason ATH is used in applications where the processing temperature remains compatible with the additive's thermal behavior. If the compound is exposed to excessive heat during manufacturing, premature decomposition may cause moisture-related defects, processing instability, or changes in the finished material.

3.2 Water Vapor Release and Gas Dilution

Water vapor released during ATH decomposition can dilute combustible gases close to the heated surface. It also contributes to the cooling effect associated with the decomposition reaction. These effects may reduce the conditions that support flame development in a suitable formulation.

How Water Vapor Contributes

  • Absorbs part of the thermal energy during the decomposition process.
  • Dilutes some combustible gases near the material surface.
  • Contributes to a reduction in the temperature of the heated polymer region.

The amount and timing of water release matter. A grade must be suitable for the polymer's processing window so that it remains stable during manufacturing and decomposes under the intended fire-exposure conditions.

3.3 Formation of an Aluminium Oxide Residue

After dehydration, ATH leaves an aluminium oxide-containing residue. In some polymer systems, this solid material can contribute to a barrier layer that influences heat transfer and the movement of volatile decomposition products. The extent of this effect depends on how the residue forms and remains within the burning material.

  • Barrier contribution: The solid residue may help limit heat and mass transfer.
  • Surface protection: The residue can contribute to the structure of the remaining solid layer.
  • Formulation dependence: Residue integrity varies with polymer chemistry, ATH loading, and other ingredients.

These mechanisms work together rather than independently. A well-designed formulation must provide suitable filler dispersion and sufficient additive content without compromising the mechanical properties and processing behavior required for the final product.

3.4 Smoke and Fire-Gas Considerations

ATH can contribute to smoke-performance objectives in selected formulations, but it should not be described as guaranteeing a specific smoke reduction or toxicity result. Smoke density, gas composition, and corrosivity depend on the complete material composition and combustion conditions.

For wire and cable applications, manufacturers should identify the relevant test requirements separately. Flame propagation, smoke density, and halogen-acid gas measurements address different performance characteristics. Passing one test does not establish compliance with all other requirements.

Important Testing Considerations

  • Use the applicable flame-propagation test for the product category and destination market.
  • Evaluate smoke density separately where required.
  • Check halogen-acid gas requirements independently when the product specification calls for them.
  • Test the actual compound or finished product rather than relying only on the additive's general properties.

4. Key Properties of Aluminium Hydroxide Flame Retardant (ATH)

The performance of ATH in a polymer compound is influenced by more than its chemical identity. Purity, particle size, particle-size distribution, moisture, whiteness, surface area, and surface treatment can all affect processing and final-product characteristics. Buyers should evaluate these properties together rather than selecting a grade based on a single specification.

4.1 Purity and Chemical Composition

ATH purity indicates the proportion of aluminium hydroxide in the product according to the supplier's specified test method. Impurities and minor constituents can influence color, electrical characteristics, processing behavior, and consistency. The acceptable purity level depends on the application and the required finished-product properties.

For higher-specification applications, buyers should review the stated Al(OH)₃ content alongside other parameters such as moisture, residue, and any controlled impurity limits. A high purity figure alone does not establish that a grade is suitable for every polymer system.

4.2 Particle Size and Particle-Size Distribution

Particle size is an important factor in filler dispersion and compound performance. Fine ATH particles may offer advantages in selected formulations, but the result depends on particle-size distribution, surface characteristics, mixing equipment, and polymer compatibility.

  • D50: The median particle size, with half of the measured particle population below this value and half above it under the specified measurement method.
  • Particle-size distribution: Describes the spread of particle sizes and provides more information than D50 alone.
  • Coarse particles: May affect surface finish, thin-wall applications, or local stress concentrations in some compounds.
  • Fine particles: May improve certain dispersion or surface characteristics but can also influence viscosity and processing behavior.

When comparing ATH grades, confirm whether particle size is measured by laser diffraction or another method. Results obtained using different test methods may not be directly comparable.

4.3 Moisture Content and Thermal Stability

Moisture control is important for powder handling and polymer compounding. Excess surface moisture may contribute to bubbles, voids, surface defects, or inconsistent processing in moisture-sensitive systems. Buyers should distinguish between free moisture measured in the product and the chemically bound water that is released when ATH decomposes at elevated temperatures.

Thermal stability is another key consideration. Since ATH decomposes at a lower temperature than magnesium hydroxide, the actual processing temperature and residence time must be reviewed carefully. The relevant limit should be confirmed using the supplier's product data and the manufacturer's own processing trials.

4.4 Whiteness, Oil Absorption, and Surface Area

Additional physical properties can help determine whether an ATH grade is suitable for a specific compound:

  • Whiteness: Important for white, light-colored, and color-sensitive products.
  • Oil absorption: Can provide an indication of how the powder interacts with liquid formulation components and may influence compound viscosity.
  • Specific surface area: Affects the interaction between filler particles and the polymer or other formulation ingredients.
  • pH: May be relevant to compatibility with selected additives and quality-control requirements.
  • Conductivity: Can be important in electrical and cable applications where electrical properties are specified.

The importance of each parameter varies by application. For example, electrical cable compounds may place greater emphasis on conductivity and moisture, while decorative or surface-sensitive products may place more emphasis on whiteness and particle-size distribution.

4.5 Surface Treatment and Polymer Compatibility

ATH can be supplied in uncoated or surface-treated forms, depending on the manufacturer's product range. Surface treatment may improve compatibility with selected polymer matrices, support dispersion, and influence the interaction between filler particles and the resin.

The effect is not identical across all polymers. A treatment suitable for one resin system may not provide the same benefit in another. Buyers should confirm the treatment chemistry and evaluate the grade under the intended compounding conditions.

ATH Grade Evaluation Checklist

  • Aluminium hydroxide content and impurity limits.
  • D50 and full particle-size distribution.
  • Moisture content and loss on ignition.
  • Whiteness, oil absorption, and specific surface area.
  • Surface-treatment type and polymer compatibility.
  • Processing temperature and performance in the target formulation.

5. Main Applications of Aluminium Hydroxide Flame Retardant

Aluminium hydroxide is used in several industries because it combines mineral-filler functionality with endothermic flame-retardant behavior. The appropriate grade and loading level depend on the polymer, processing window, product design, and fire-performance requirements.

5.1 Plastics and Thermoplastics

ATH can be incorporated into selected thermoplastic compounds where the processing conditions are compatible with its thermal decomposition behavior. Potential applications include plastic components, housings, profiles, and other molded or extruded products that require specific fire-related properties.

When used in thermoplastics, manufacturers should pay particular attention to melt temperature, residence time, filler dispersion, and mechanical-property retention. High mineral-filler loading can affect flow, impact strength, elongation, and surface finish. The formulation should therefore be optimized through controlled trials.

5.2 Rubber and Elastomer Compounds

ATH is used in selected rubber and elastomer formulations as a flame-retardant additive and mineral filler. It may be evaluated in products where fire performance, smoke characteristics, and mechanical properties need to be considered together.

For rubber applications, grade selection should account for the elastomer type, curing system, mixing temperature, filler loading, and required flexibility. Dispersion and compatibility are important because poorly distributed filler can affect compound uniformity and finished-product performance.

5.3 Wire and Cable Compounds

ATH is used in selected wire and cable formulations, including certain insulation and sheathing compounds. It can contribute to flame-retardant performance and may be incorporated into halogen-free compound designs. The choice between ATH, magnesium hydroxide, or a combination of additives depends on the cable's processing temperature, polymer system, and required fire classification.

  • Power cables: ATH may be considered for compatible insulation or jacket formulations where processing conditions allow.
  • Communication cables: Selected formulations can use ATH where smoke, flame, and mechanical requirements are met.
  • Building wires: The compound must be designed and tested against the applicable product and installation standards.
  • Industrial cables: Grade selection should consider operating temperature, flexibility, abrasion resistance, and electrical performance.

For cable manufacturers, electrical properties, moisture, dispersion, and extrusion stability are important evaluation criteria. A formulation should be assessed using the required cable-level tests rather than assuming compliance from the ATH content alone.

5.4 Thermoset Composites and Fiberglass-Reinforced Products

ATH is widely considered for selected thermoset composite systems, including unsaturated polyester and fiberglass-reinforced products. Potential applications include panels, molded components, electrical enclosures, and other composite products where fire-related performance and appearance are important.

In thermoset formulations, the filler can influence viscosity, wet-out, curing behavior, surface quality, and mechanical properties. Manufacturers should verify the compatibility of ATH with the resin and reinforcement system and check whether the selected loading level can be processed consistently.

5.5 Building Materials, Sealants, and Coatings

ATH may also be used in selected construction-related products, including sealants, adhesives, coatings, and other building materials. In these applications, it can serve as a mineral filler while contributing to the formulation's fire-performance objectives.

The relevant selection factors may include viscosity, settling behavior, adhesion, flexibility, surface finish, and compatibility with other ingredients. Fire-test requirements vary by product category, so the finished material must be assessed against the appropriate standard.

Application Selection Overview

Application Main Evaluation Factors
Thermoplastics Processing temperature, melt flow, dispersion, and mechanical properties
Rubber and elastomers Compatibility, flexibility, curing behavior, and filler dispersion
Wire and cable Thermal stability, extrusion behavior, electrical properties, and cable fire tests
Thermoset composites Resin compatibility, viscosity, wet-out, curing, and surface finish
Sealants and coatings Rheology, settling, adhesion, flexibility, and product-specific fire performance

These application categories are starting points for technical evaluation. They do not indicate that one ATH grade is suitable for every product within a category.

6. Advantages and Limitations of Aluminium Hydroxide

ATH offers several useful characteristics for manufacturers developing flame-retardant materials. However, its performance is influenced by formulation design and processing conditions. Understanding both its advantages and limitations helps buyers decide whether ATH is appropriate for a particular product.

6.1 Main Advantages

  • Halogen-free chemical composition: ATH itself contains no bromine or chlorine and can be used in halogen-free formulation designs.
  • Endothermic decomposition: It absorbs heat and releases water vapor when exposed to sufficient temperatures.
  • Multiple application possibilities: It can be evaluated in selected plastics, rubber, cable, composite, sealant, and coating systems.
  • Mineral-filler functionality: It can contribute to the filler content of a compound as well as its flame-retardant design.
  • White appearance: Its color can be useful in light-colored products and formulations where appearance matters.
  • Combination potential: It can be used with other compatible additives where formulation trials demonstrate a benefit.

6.2 Limitations and Formulation Challenges

  • Relatively low decomposition temperature: ATH may not be suitable for every high-temperature polymer-processing system. Processing conditions must be checked carefully.
  • High filler loading may be required: Some formulations need substantial ATH content to reach their target fire performance, which can affect flexibility, elongation, impact strength, and flow.
  • Dispersion requirements: Poor dispersion can lead to inconsistent properties and surface defects.
  • Moisture management: Surface moisture and storage conditions can affect powder handling and processing in moisture-sensitive systems.
  • Application-specific performance: ATH cannot guarantee a particular fire classification or smoke result without testing the complete formulation.

Important Formulation Note

A higher ATH loading does not automatically produce a better finished product. Manufacturers must balance fire performance with mechanical properties, processing stability, surface quality, and total compound cost. Final approval should be based on controlled formulation trials and the required product tests.

6.3 When Should Manufacturers Consider Another Flame Retardant?

If the polymer must be processed at temperatures above the practical thermal-stability range of the selected ATH grade, manufacturers may need to evaluate another flame-retardant system. Magnesium hydroxide is one option because it generally decomposes at a higher temperature than ATH. Other additives or synergistic systems may also be considered, depending on the required fire performance and regulatory conditions.

The decision should be based on the actual processing window and finished-product requirements rather than on a general assumption that one additive is always better than another.

7. ATH vs. Magnesium Hydroxide: Key Differences

Aluminium hydroxide (ATH) and magnesium hydroxide (MDH) are both inorganic, halogen-free flame-retardant additives. Both absorb heat and release water during thermal decomposition, but they differ in chemical composition, decomposition temperature, water content, and suitability for different processing conditions.

ATH is often considered for applications with processing temperatures compatible with its thermal behavior. MDH generally has a higher decomposition temperature, making it a candidate for selected higher-temperature polymer systems. The choice depends on the polymer, formulation, processing window, fire-test requirements, and material cost.

7.1 Technical Comparison

Comparison Factor Aluminium Hydroxide (ATH) Magnesium Hydroxide (MDH)
Chemical Formula Al(OH)₃ Mg(OH)₂
Typical Decomposition Range Approximately 180–220°C Approximately 330–340°C
Theoretical Water Content Approximately 34.6% by mass Approximately 30.9% by mass
Primary Decomposition Residue Aluminium oxide (Al₂O₃) Magnesium oxide (MgO)
Thermal Stability Suitable for compatible lower-temperature processing systems Generally suitable for selected higher-temperature processing systems
Typical Evaluation Areas Thermoset composites, selected plastics, rubber, and cable compounds Selected HFFR cable compounds, engineering plastics, and higher-temperature systems
Key Selection Consideration Processing temperature and filler-loading effects Grade cost, dispersion, and formulation optimization

The decomposition ranges shown are general reference values. Actual thermal behavior varies with grade characteristics, particle size, heating rate, atmosphere, and measurement method. Buyers should compare product-specific data rather than treating these figures as fixed processing limits.

7.2 Which Additive Should You Choose?

Practical Selection Guidance

  • Consider ATH when the processing temperature is compatible with the selected grade and the formulation benefits from its filler and flame-retardant characteristics.
  • Consider MDH when a higher thermal-stability window is important for the selected polymer and compounding process.
  • Evaluate ATH/MDH combinations when a formulation may benefit from balancing thermal behavior, cost, and other compound properties.
  • Test the complete formulation before making a production decision, especially when changing the additive type or loading level.

ATH and MDH should not be compared on decomposition temperature alone. Mechanical properties, dispersion, fire performance, processing efficiency, supply consistency, and total formulation cost all influence the final selection.

KMT Industrial material handling and loading operations

8. Formulation Factors That Influence ATH Performance

The performance of aluminium hydroxide depends on how it interacts with the polymer and the rest of the formulation. A technically suitable grade can still produce unsatisfactory results if it is poorly dispersed, used outside its processing window, or added at an unsuitable concentration.

8.1 Polymer Type and Compatibility

Different polymers have different thermal properties, melt behavior, chemical structures, and mechanical requirements. ATH should be evaluated in the actual resin system rather than selected based only on its general flame-retardant characteristics.

For thermoplastics, melt temperature and processing time are important. For rubber, mixing and curing conditions need to be considered. In thermoset composites, resin viscosity, filler wet-out, and curing behavior can affect the result.

8.2 ATH Loading Level

The amount of ATH in a compound can influence flame behavior, heat release, smoke characteristics, mechanical properties, and processing. Some formulations require relatively high mineral-filler content to achieve their target fire performance, but increasing the loading may also raise viscosity and reduce flexibility or elongation.

There is no single ATH loading level that is suitable for every polymer or application. The correct concentration must be established through formulation screening, with results assessed against the required fire tests and physical-property specifications.

8.3 Particle Size and Dispersion Quality

Particle size can affect filler distribution, viscosity, surface quality, and mechanical performance. The mixing process must provide adequate dispersion without causing excessive heat buildup or damaging the polymer. Buyers should review both D50 and the complete particle-size distribution when comparing candidate grades.

Dispersion quality should be evaluated using the actual production process. A powder that performs well in a laboratory mixer may behave differently in an industrial extruder, kneader, or compounding line.

8.4 Surface Treatment and Additive Compatibility

Surface treatment can change how ATH interacts with the polymer matrix. Depending on the coating chemistry, it may influence powder flow, filler wetting, dispersion, and interfacial properties. The benefit should be confirmed for the specific polymer and processing method.

Other ingredients, including coupling agents, processing aids, stabilizers, pigments, and additional flame retardants, may also affect compound performance. Changes to one ingredient can influence the behavior of the complete formulation.

8.5 Processing Temperature and Residence Time

ATH must remain sufficiently stable during the manufacturing process. Excessive processing temperature or prolonged residence time may cause premature decomposition and moisture release. This can affect surface appearance, compound consistency, and production stability.

Manufacturers should compare the actual material temperature—not only the equipment's set temperature—with the thermal characteristics of the selected grade. Screw design, shear heating, throughput, and material residence time should also be considered.

8.6 Fire-Test Requirements and Product Design

The required fire performance depends on the end product and its market. A cable, molded plastic component, composite panel, and sealant may be subject to different test methods. Sample thickness, product geometry, installation conditions, and test preparation can all affect the result.

Before selecting an ATH grade, identify the exact standard, test specimen, thickness, and acceptance criteria. This makes it easier to define a realistic formulation-development plan.

ATH Performance Evaluation Checklist

  • Confirm the polymer type and processing temperature.
  • Define the required fire and smoke test standards.
  • Compare ATH purity, D50, particle-size distribution, and moisture.
  • Evaluate uncoated and surface-treated grades where relevant.
  • Measure dispersion, viscosity, flow, and mechanical properties.
  • Test the finished compound or product under the required conditions.

9. KMT Industrial Aluminium Hydroxide Product

KMT Industrial supplies industrial mineral products, including aluminium hydroxide for applications that require controlled powder properties. When evaluating ATH for flame-retardant formulations, buyers should consider the product's chemical content, particle size, whiteness, moisture, and other specifications in relation to their own processing and performance requirements.

KMT Industrial's aluminium hydroxide product lists an A1 grade with defined technical parameters. These specifications can serve as a starting point for assessing whether the material is suitable for a particular application. Final suitability should be confirmed through a review of the current TDS and application testing.

9.1 KMT A1 Grade Technical Specifications

The following table summarizes the A1 grade specifications listed on KMT Industrial's product page. These are product-specific figures and should not be treated as universal specifications for all aluminium hydroxide flame retardants.

Parameter KMT A1 Grade Specification Potential Relevance
Al(OH)₃ Content ≥99.40% Indicates the specified aluminium hydroxide content.
D50 Particle Size 1.40–1.80 μm Provides a median particle-size reference for formulation screening.
Whiteness ≥95 Relevant to light-colored and appearance-sensitive products.
Processing Temperature <208°C A product-specific processing reference; confirm the test basis and actual application conditions.
Moisture ≤0.4% Relevant to powder handling and moisture-sensitive processing.
Oil Absorption ≤30 ml/100g Can help assess filler interaction with liquid formulation components.
pH ≤9 A quality-control parameter for formulation compatibility.
Conductivity ≤35 μS/cm May be relevant to applications with electrical-property requirements.
Loss on Ignition (LOI) 34.5±0.2% A reference for mass loss under the specified test conditions.
Specific Surface Area 3–5 m²/g Relevant to filler-polymer interaction and formulation behavior.
Surface Treatment Non-coated Provides an uncoated starting point for compatibility evaluation.

Specification note: Confirm the current product data sheet, test methods, and batch-specific COA with KMT Industrial before placing an order. The listed processing-temperature figure is a product specification reference, not a universal guarantee of processing suitability for every polymer or production line.

9.2 Evaluating KMT A1 Grade for Your Formulation

KMT A1 grade can be considered for preliminary screening where the specified purity, particle size, whiteness, and other product characteristics align with the buyer's requirements. Its non-coated status should also be considered when evaluating polymer compatibility and the potential need for a coupling agent or other formulation adjustment.

  • Purity requirements: Compare the stated Al(OH)₃ content with the application specification and any impurity limits.
  • Particle-size requirements: Check whether the D50 range and full particle-size distribution are appropriate for the target compound.
  • Moisture control: Review the moisture specification and confirm storage and handling requirements.
  • Processing compatibility: Compare the product's thermal characteristics with the actual material temperature and residence time.
  • Surface compatibility: Evaluate whether an uncoated grade provides sufficient dispersion in the selected polymer system.

For more information about the product, visit KMT Industrial's aluminium hydroxide page. Buyers can also contact the company to request current technical documentation and discuss application requirements.

9.3 Product Information and Supplier Communication

When requesting a quotation, provide the intended application, polymer type, required ATH content, target particle size, and processing conditions. If the material is being used in a regulated or safety-critical product, include the relevant test standards and technical acceptance criteria.

Contact KMT Industrial to discuss product specifications, sample availability, and purchasing requirements.

10. Practical Steps for Selecting an Aluminium Hydroxide Grade

Selecting an appropriate ATH grade requires a systematic review of the application, polymer system, processing conditions, and required fire performance. The following steps can help manufacturers compare products and reduce the risk of choosing a grade based on incomplete specifications.

10.1 Define the End Application and Polymer

Start by identifying the product being manufactured and the polymer or resin used. Cable compounds, rubber products, thermoplastics, thermoset composites, and coatings have different processing and performance requirements. The application determines which ATH properties should receive the greatest attention.

  • Identify the resin or elastomer type and its processing-temperature range.
  • Confirm whether the product is extruded, molded, calendered, cast, or coated.
  • Define the required flexibility, tensile strength, elongation, impact resistance, and surface finish.
  • Identify the fire, smoke, and other product-specific requirements.

10.2 Compare Technical Specifications

Review the technical data sheets of candidate ATH grades. Compare the test methods and units used by each supplier to ensure that the specifications are meaningfully comparable.

Specification What to Check Why It Matters
Chemical content Al(OH)₃ content and impurity limits Supports material consistency and specification compliance.
Particle size D50 and particle-size distribution Influences dispersion, flow, and surface properties.
Moisture Specified moisture content and test method Helps assess handling and moisture-sensitive processing risks.
Whiteness Whiteness value and measurement method Important for appearance-sensitive products.
Oil absorption Value and test method Can affect formulation viscosity and filler interaction.
Surface treatment Coated or uncoated; treatment chemistry where applicable Influences polymer compatibility and dispersion.
Thermal behavior Thermal analysis data and recommended processing conditions Helps assess compatibility with manufacturing temperatures.

10.3 Evaluate Loading Level and Total Formulation Cost

Do not compare ATH grades only by their price per kilogram. A more useful comparison considers the total cost of the finished compound, including filler loading, processing efficiency, scrap rate, and the effect on mechanical properties.

Use a controlled formulation study to evaluate several loading levels. Record the formulation basis clearly, such as weight percentage of the total compound, and avoid comparing results calculated on different bases. The target loading should be determined by the required fire performance and physical properties.

10.4 Check Processing Conditions

Review the actual processing temperature, residence time, mixing energy, equipment configuration, and material-feeding method. ATH should be stable under the selected manufacturing conditions. For extrusion and compounding, monitor torque, melt pressure, throughput, surface quality, and any signs of premature decomposition.

10.5 Conduct Laboratory and Production Trials

Before approving a grade for regular production, compare candidate products under the same formulation and processing conditions. Depending on the application, the evaluation may include:

  • Powder flow, moisture, and dispersion assessment.
  • Melt flow, compound viscosity, processing torque, and extrusion stability.
  • Tensile strength, elongation, impact strength, and aging performance.
  • Flame propagation, heat release, smoke density, or other required fire tests.
  • Finished-product appearance, dimensional stability, and electrical properties where applicable.

Only approve a grade after the test results meet the relevant product specifications. Laboratory plaques or small test specimens may help with initial screening, but they do not replace finished-product testing where the applicable standard requires it.

10.6 Confirm Supplier Documentation and Supply Capability

Technical suitability is only one part of supplier qualification. Buyers should also review documentation, batch consistency, production capacity, packaging, lead time, and the supplier's ability to support repeat orders.

Supplier Qualification Checklist

  • Current technical data sheet and safety data sheet.
  • Batch-specific certificate of analysis and agreed acceptance limits.
  • Verified purity, particle size, moisture, and surface-treatment information.
  • Relevant quality-management certificates and regulatory declarations, where applicable.
  • Sample availability and technical communication arrangements.
  • Packaging, minimum order quantity, production lead time, and delivery terms.

For product specifications or quotation inquiries, contact KMT Industrial with your application details and technical requirements.

11. Conclusion and Recommendations

Aluminium hydroxide flame retardant (ATH) is an important inorganic additive for manufacturers developing selected plastics, rubber, wire and cable compounds, thermoset composites, and construction-related materials. Its endothermic decomposition, water-vapor release, and aluminium oxide residue can contribute to flame-retardant performance when the additive is properly matched to the polymer and application.

The right ATH grade depends on several factors, including purity, particle size, moisture, surface treatment, processing temperature, filler loading, and polymer compatibility. Manufacturers should also consider the influence of ATH on viscosity, mechanical properties, surface finish, and production efficiency. No single grade or loading level is suitable for every formulation.

KMT Industrial's A1 aluminium hydroxide grade lists an Al(OH)₃ content of at least 99.40%, a D50 particle size of 1.40–1.80 μm, and other defined product specifications. These figures provide a starting point for technical evaluation, but buyers should confirm current documentation and conduct application-specific testing before production approval.

To explore product details, visit KMT Industrial's aluminium hydroxide product page. Contact the company to discuss technical specifications, sample availability, and supply requirements for your application.

Need Technical Support?

Contact KMT Industrial to discuss aluminium hydroxide specifications, product documentation, and your flame-retardant material requirements.

Website: www.kmtindustrial.com | Product: Aluminium Hydroxide