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Ammonium Polyphosphate, APP, 68333-79-9

Ammonium Polyphosphate, APP, 68333-79-9

AMMONIUM POLYPHOSPHATE (APP)

1. CHEMICAL IDENTITY AND DEFINITION

Parameter Information
Chemical Name Ammonium Polyphosphate
Chemical Formula (NH₄PO₃)ₙ
Molecular Weight Variable (polymer, depends on chain length)
Appearance White powder or granules
CAS Number 68333-79-9
EC Number (EINECS) 269-789-9
Chemical Class Inorganic polyphosphate salt
Odor Odorless or faint ammonia-like odor
Physical State (20°C) Solid (powder or granules)
Color White to off-white

2. WHAT IS APP?

Ammonium Polyphosphate (APP) is an inorganic salt consisting of long-chain polyphosphate polymers with ammonium ions. It is widely used as a halogen-free, environmentally friendly flame retardant due to its ability to form a protective char layer when exposed to heat. The chain length varies depending on the production process and intended application.

3. PHYSICAL PROPERTIES

Property APP I (Short Chain) APP II (Long Chain)
Appearance White powder White powder or granules
Solubility in Water (20°C) High (> 50 g/100 mL) Low (< 1 g/100 mL)
Hygroscopicity High Low
Thermal Stability Lower (< 200°C decomposition) Higher (> 240°C decomposition)
pH (1% aqueous solution) ~5.0 - 6.0 ~5.5 - 6.5
Density (bulk) ~1.7 - 1.8 g/cm³ ~1.8 - 1.9 g/cm³
Particle Size Fine powder (D50 ~15-20 µm) Variable (powder to granular)
Melting Point Decomposes before melting Decomposes before melting

4. CHEMICAL PROPERTIES

Property Information
Chemical Formula (NH₄PO₃)ₙ
CAS Number 68333-79-9
EC Number (EINECS) 269-789-9
Chemical Class Inorganic polyphosphate salt
Molecular Weight Variable (n = 20 to > 1000)
Structure Linear chain of phosphate units with ammonium counterions
Phosphorus Content (P₂O₅) ~70 - 72%
Nitrogen Content ~12 - 14%
Decomposition Temperature > 240°C (APP II)
Solubility in Water Varies by type (low for APP II, high for APP I)
Solubility in Organic Solvents Insoluble
Stability Stable under normal storage conditions
Hygroscopicity APP II: Low; APP I: High

5. CHEMICAL STRUCTURE

        O        O        O        O
        ||       ||       ||       ||
   NH₄⁺ - O - P - O - P - O - P - O - P - O - NH₄⁺
              |        |        |        |
              O⁻       O⁻       O⁻       O⁻

(Ammonium Polyphosphate - Linear Chain Structure)

Chain Length Representation:

  • APP I (Short Chain): n < 100 units

  • APP II (Long Chain): n > 1000 units

6. COMPARISON OF APP TYPES: APP I vs APP II

Property APP I (Short Chain) APP II (Long Chain)
Chain Length Short (n < 100) Long (n > 1000)
Water Solubility High Low
Hygroscopicity High Low
Thermal Stability Lower (decomposes < 200°C) Higher (decomposes > 240°C)
Flame Retardancy Moderate High
Foaming Ability High Low
Preferred Application Fertilizers, water treatment Flame retardants, coatings
Processability Easier to process More challenging to process
Cost Lower Higher

7. MECHANISM OF ACTION (FLAME RETARDANT)

Step Description
1 APP is exposed to heat / fire
2 Thermal decomposition begins (> 240°C)
3 Ammonia (NH₃) and phosphoric acid (H₃PO₄) are released
4 Phosphoric acid reacts with organic materials (carbonization)
5 Protective char layer forms on material surface
6 Char layer acts as insulation: cuts off oxygen and heat transfer
7 Ammonia and water vapor dilute combustible gases
8 Combustion is slowed or completely prevented
9 Smoke emission is reduced significantly
10 Flame spread is minimized

8. FLAME RETARDANT MECHANISM - INTUMESCENT SYSTEM

Component Role
APP (Acid Source) Releases phosphoric acid upon heating, acts as dehydrating agent
Carbon Source (e.g., Pentaerythritol) Reacts with acid to form carbonaceous char
Blowing Agent (e.g., Melamine) Releases gas to expand char into foam structure
Result Swollen, insulating char layer that protects substrate

9. APPLICATIONS - PLASTICS AND POLYMERS

Material Application Description
Epoxy Resins Flame retardant additive for electrical and construction applications
Polyurethane (PU) Rigid and flexible foams; flame retardant modification
Polyester Resins Unsaturated polyester composites, automotive parts
Polyethylene (PE) Wire and cable insulation, packaging materials
Polypropylene (PP) Automotive components, appliances, textiles
Polyamide (PA/Nylon) Engineering plastics, electrical components
Acrylonitrile Butadiene Styrene (ABS) Electronics housings, automotive parts
Polycarbonate (PC) Electrical and electronic applications

10. APPLICATIONS - COATINGS AND CONSTRUCTION

Application Description
Intumescent Coatings Swelling fire-retardant paints for structural steel protection
Building Materials Fire-resistant panels, boards, and insulation materials
Fireproof Sealants Sealants for fire-rated joints and penetrations
Roofing Materials Fire-resistant roofing membranes and coatings
Cable Coatings Flame retardant coatings for electrical cables
Concrete Additives Fire resistance enhancement for concrete structures

11. APPLICATIONS - TEXTILES, PAPER AND WOOD

Application Description
Textile Treatment Flame retardant treatment for fabrics, curtains, upholstery
Technical Textiles Protective clothing, tent fabrics, industrial textiles
Paper Products Fire-resistant paper, cardboard, and packaging materials
Wood Treatment Impregnation for wood, plywood, and engineered wood products
Furniture Flame retardant applications in furniture manufacturing

12. APPLICATIONS - FERTILIZERS AND AGRICULTURE

Application Description
Slow-Release Fertilizers Controlled-release phosphorus source for agriculture
Liquid Fertilizers Water-soluble APP I in liquid fertilizer formulations
Granular Fertilizers Coated or blended with other nutrients for soil application
Foliar Sprays Phosphorus and nitrogen source for foliar application
Hydroponics Nutrient source for hydroponic growing systems
Soil Amendment Improves phosphorus availability in soils

13. APPLICATIONS - WATER TREATMENT AND INDUSTRY

Application Description
Metal Ion Binding Chelating agent for heavy metal ions in water treatment
Corrosion Inhibitor Protective additive in industrial water systems
Boiler Water Treatment Scale inhibition and corrosion protection
Cooling Water Systems Anti-scaling and anti-corrosion agent
Detergent Additives Builder and chelating agent in detergents
Adhesives and Sealants Flame retardant component in adhesive formulations

14. ADVANTAGES OF APP

Advantage Description
Halogen-Free No halogens (chlorine, bromine, fluorine, iodine)
Environmentally Friendly Low toxic byproduct emissions during combustion
Low Smoke Emission Significantly reduces smoke generation during fire
Non-Toxic Low acute toxicity to humans and animals
Synergistic Effects Can be combined with other flame retardants for enhanced performance
Cost-Effective Economically viable compared to other flame retardants
Versatile Applicable to wide range of polymers and materials
UV Resistant Good resistance to ultraviolet degradation
Thermal Stability Stable up to 240°C, suitable for processing at high temperatures
Sustainable Compatible with modern sustainability and green chemistry principles

15. SAFETY AND TOXICOLOGY

Parameter Value
Oral LD50 (Rat) > 10,000 mg/kg (estimated)
Dermal LD50 (Rabbit) > 5,000 mg/kg (estimated)
Inhalation LC50 (Rat) > 5 mg/L (estimated)
Skin Irritation May cause mild irritation
Eye Irritation May cause mechanical irritation
Skin Sensitization Not expected to be a sensitizer
Carcinogenicity Not classified as carcinogenic (IARC, NTP, OSHA)
Mutagenicity Not classified as mutagenic
Reproductive Toxicity No evidence of adverse effects
Environmental Toxicity Low aquatic toxicity (EC50 > 100 mg/L)
Bioaccumulation Not expected to bioaccumulate
Persistence Readily biodegradable

16. SIDE EFFECTS AND PRECAUTIONS

Condition Description
Dust Formation Inhalation of fine powder may cause respiratory irritation
Skin Contact May cause mild irritation; use protective gloves
Eye Contact May cause mechanical irritation; use safety goggles
Moisture Sensitivity APP I is highly hygroscopic; store in dry conditions
High Temperature Decomposes above 240°C releasing ammonia and phosphorus oxides
Incompatibilities Strong acids, strong oxidizing agents, strong bases
Worker Protection Use local exhaust ventilation; wear dust mask if dust is generated

17. HANDLING AND STORAGE

Parameter Information
Storage Temperature 15-25°C (cool, ambient temperature)
Storage Conditions Cool, dry, well-ventilated area
Relative Humidity < 50% for APP I; < 70% for APP II
Container Requirements Tightly closed, original packaging
Protect From Moisture, heat, strong acids, strong alkalis, strong oxidizing agents
Shelf Life 12-24 months (in unopened original packaging, dry conditions)
Handling Precautions Avoid dust generation; use local exhaust ventilation
Spill Cleanup Sweep or vacuum; avoid generating dust; dispose properly
Disposal In accordance with local, national, and international regulations

18. DECOMPOSITION AND BYPRODUCTS

Temperature Decomposition Products Hazard
> 240°C Ammonia (NH₃) and phosphoric acid (H₃PO₄) Irritant gases
> 300°C Phosphorus oxide (P₂O₅), water vapor Respiratory irritant
> 400°C Phosphorus oxides (P₂O₅, POₓ), ammonia Toxic, irritant
> 600°C Metal phosphates, residual carbon char Solid residue

Firefighting Recommendations:

  • Use water spray, foam, or dry powder extinguishers

  • Wear self-contained breathing apparatus (SCBA)

  • Avoid contact with decomposition products

  • Prevent runoff from entering waterways

19. PACKAGING OPTIONS

Packaging Type Quantity Material
Kraft Bag with PE Inner Liner 25 kg Kraft paper + PE
Plastic Bucket with Lid 20-25 kg HDPE
Aluminum Foil Bag 1-5 kg Laminated aluminum
Plastic Bag (Multi-layer) 25 kg HDPE/LDPE
Big-Bag (FIBC) 500 kg Polypropylene woven fabric
Big-Bag (FIBC) 1000 kg Polypropylene woven fabric
Drum (Fiber/Plastic) 50 kg Fiberboard or HDPE
Custom Packaging As per customer requirements Various materials

20. TRANSPORT INFORMATION

Parameter Information
UN Number Not regulated (not a hazardous material for transport)
Hazard Class Not applicable
Packing Group Not applicable
ADR/RID Not regulated
IMDG Code Not regulated
IATA (Air) Not regulated
Marine Pollutant No
Transport Temperature Ambient
Labeling Requirements None required for transport

21. REGULATORY STATUS

Region / Authority Status
European Union (REACH) Registered substance
USA (EPA TSCA) Listed on TSCA inventory
China (MEE) Approved for use in flame retardants
Japan (CSCL) Listed on CSCL inventory
South Korea (K-REACH) Registered substance
EFSA Approved for use in food contact materials (limited)
EU Classification Not classified as hazardous under CLP Regulation

22. QUALITY SPECIFICATIONS (TYPICAL APP II)

Parameter Specification
Appearance White powder or granules
P₂O₅ Content ≥ 70.0%
Nitrogen Content ≥ 12.0%
Solubility in Water ≤ 1.0%
pH (1% aqueous) 5.5 - 6.5
Moisture Content (H₂O) ≤ 0.5%
Particle Size (D50) 15 - 20 µm (powder grade)
Thermal Stability Stable up to 240°C
Degree of Polymerization > 1000 units
Insoluble in Water ≥ 99.5%

23. SUMMARY AND CRITICAL WARNINGS

Product Summary

Parameter Value
Product Ammonium Polyphosphate (APP)
CAS Number 68333-79-9
EC Number 269-789-9
Appearance White powder or granules
Chemical Class Inorganic polyphosphate
Primary Function Halogen-free flame retardant, fertilizer, water treatment
Phosphorus Content ~70 - 72% P₂O₅
Nitrogen Content ~12 - 14%

CRITICAL WARNINGS

1. APP I vs APP II Selection: Choose APP I (short chain) for fertilizers and water treatment applications due to high solubility. Choose APP II (long chain) for flame retardant applications due to low solubility and high thermal stability.

2. Thermal Stability: APP II remains stable up to 240°C; above this temperature, decomposition begins with release of ammonia and phosphoric acid.

3. Moisture Sensitivity: APP I is highly hygroscopic and must be stored in sealed containers with low humidity. APP II is less sensitive but should still be protected from moisture.

4. Halogen-Free: Contains no halogens; produces low toxic byproducts compared to halogenated flame retardants. Environmentally preferred.

5. Char Formation: The protective char layer is critical for flame retardant action; it insulates the material and cuts off oxygen supply.

6. Intumescent Systems: APP works best in combination with carbon sources (e.g., pentaerythritol) and blowing agents (e.g., melamine) for intumescent flame retardancy.

7. Application Versatility: Suitable for plastics (PP, PE, PA, PU, epoxy, polyester), coatings, textiles, paper, wood, fertilizers, and water treatment.

8. Environmental Benefits: Low toxicity, environmentally friendly, non-bioaccumulative, and complies with modern flame retardant regulations.

9. Decomposition Byproducts: At high temperatures (> 240°C), ammonia and phosphorus oxides are released; use appropriate ventilation and respiratory protection.

10. Occupational Safety: Use dust masks, safety goggles, and protective gloves when handling to avoid irritation from dust.

11. Regulatory Compliance: Ensure compliance with REACH, TSCA, and other regional regulations for the intended application.

12. Fire Protection: APP is not combustible but contributes to fire resistance of treated materials. It should not be used as a standalone fire suppressant.

13. Food Contact: Limited approval for food contact materials; check regional regulations before using in food packaging.

14. Storage Conditions: Store in a cool, dry place. Avoid exposure to moisture, acids, alkalis, and oxidizing agents.

15. Shelf Life: Up to 24 months in unopened, properly sealed packaging. Monitor for caking or moisture absorption over time.

IMPORTANT DISCLAIMER: This Technical Data Sheet (TDS) is for informational purposes only and is prepared based on available technical data. The user is responsible for determining the suitability of the product for their specific application and for complying with all local, national, and international regulations. For complete safety, storage, use, handling, disposal, and regulatory compliance information, refer to the official Safety Data Sheet (SDS/MSDS) provided by the manufacturer/supplier. This document is not a substitute for professional or medical advice.

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