EXOLIT AP 740

Exolit AP 740 is a non-halogenated additive flame retardant based on polymeric ammonium polyphosphate and designed to deliver efficient condensed-phase flame retardancy through phosphorus and nitrogen synergism.
Exolit AP 740 works primarily by promoting intumescence, meaning Exolit AP 740 helps form an expanded char foam layer under fire exposure that insulates the substrate and reduces heat transfer and oxygen access.
Exolit AP 740 is widely used in thermoset resin systems and intumescent coating formulations where low smoke development, improved fire performance, and robust processing behavior are required.

CAS Number: 68333-79-9 (ammonium polyphosphate; polymeric)
EC Number: 269-789-9 (commonly associated; polymeric APP listing)
Molecular Formula: (NH4PO3)n (polymeric; degree of polymerization dependent)
Molecular Weight: Variable (polymer)

Synonyms: Exolit AP 740, Exolit® AP 740, Ammonium Polyphosphate, Polymeric Ammonium Polyphosphate, APP Flame Retardant, APP Intumescent Flame Retardant, Phosphorus-Nitrogen Flame Retardant, Halogen-Free Flame Retardant APP, Ammonium Polyphosphate Powder, Intumescent Acid Donor, Polyphosphate Flame Retardant, Exolit AP Series APP, Exolit AP 740, EXOLIT AP 740, Exolit® AP 740, EXOLIT® AP 740, Exolit AP740, EXOLIT AP740, Exolit AP-740, EXOLIT AP-740, Exolit AP 740 (trade name), Exolit AP 740 flame retardant, Exolit AP 740 FR, Exolit AP 740 fire retardant (variant), Exolit AP 740 intumescent flame retardant (use context), Exolit AP 740 phosphorus flame retardant (use context), Exolit AP 740 ammonium polyphosphate (context), Exolit AP 740 APP (context), Exolit AP 740 (ammonium polyphosphate), Exolit AP 740 (APP), APP 740 (context), Ammonium Polyphosphate (Exolit AP 740) (context), Exolit AP 740 polymeric ammonium polyphosphate (context), Polymeric Ammonium Polyphosphate (Exolit AP 740) (context), Exolit AP 740 (phase II ammonium polyphosphate) (use context),

APPLICATIONS

Exolit AP 740 is used in intumescent coatings to promote rapid char formation and protect steel structures under fire exposure.
Exolit AP 740 is incorporated into waterborne intumescent coatings to provide phosphorus acid donor functionality in compatible binder systems.
Exolit AP 740 is used in solventborne intumescent coatings where intumescent expansion and char integrity are critical for fire protection.

Exolit AP 740 is used in unsaturated polyester (UPR) resins to improve flame retardancy of gelcoats and laminates.
Exolit AP 740 is incorporated into polyester gelcoats to reduce flame spread and support lower smoke density in composite applications.
Exolit AP 740 is used in fiberglass-reinforced polyester parts to improve fire behavior in transportation and building applications.

Exolit AP 740 is used in epoxy resins to enhance condensed-phase flame retardancy and improve char yield.
Exolit AP 740 is incorporated into epoxy gelcoats and protective coatings to support better fire performance on composites.
Exolit AP 740 is used in epoxy casting and laminating systems where halogen-free flame retardancy is required.

Exolit AP 740 is used in phenolic resin systems to reinforce char formation and improve heat insulation under fire.
Exolit AP 740 is incorporated into phenolic composites to support low smoke generation and improved fire resistance.
Exolit AP 740 is used in phenolic-based molding compounds where condensed-phase protection is preferred.

Exolit AP 740 is used in acrylic resin coatings to improve fire performance while maintaining coating processability.
Exolit AP 740 is incorporated into architectural and industrial coating systems where intumescent protection is targeted.
Exolit AP 740 is used in flame-retardant paint systems as part of complete intumescent packages with carbon sources and blowing agents.

Exolit AP 740 is used in fiber-reinforced plastics to improve flame retardancy of composite skins and surface layers.
Exolit AP 740 is incorporated into composite matrices to reduce dripping and improve self-protective char behavior.
Exolit AP 740 is used in sandwich panel skins where fire barriers and reduced heat release are required.

Exolit AP 740 is used in construction composites and panels to improve reaction-to-fire performance in compatible binder systems.
Exolit AP 740 is incorporated into mineral-filled resin systems to enhance char strength and reduce flame spread.
Exolit AP 740 is used in building materials where halogen-free flame retardancy and low smoke are priorities.

Exolit AP 740 is used in sealing and gap-filling compounds where intumescent expansion can improve fire blocking performance.
Exolit AP 740 is incorporated into firestop sealants to support swelling char formation under heat exposure.
Exolit AP 740 is used in cable penetration and joint firestop systems where inorganic char formation is desirable.

Exolit AP 740 is used in adhesive formulations where flame retardancy is required in bonded assemblies.
Exolit AP 740 is incorporated into structural adhesives for composite parts to support improved fire performance in selected systems.
Exolit AP 740 is used in laminating adhesives when char-forming behavior is needed under flame exposure.

Exolit AP 740 is used in specialty coatings for wood and plastics where intumescent protection improves fire behavior.
Exolit AP 740 is incorporated into protective coatings for interior building components to reduce flame spread risk.
Exolit AP 740 is used in decorative coatings where halogen-free flame retardancy is required with good visual finish.

Exolit AP 740 is used in formulation development as an APP base for intumescent systems combined with synergists such as pentaerythritol, melamine, and mineral flame retardants.
Exolit AP 740 is incorporated into optimized fire protection packages to balance expansion, char strength, durability, and processing.
Exolit AP 740 is valued because Exolit AP 740 provides effective halogen-free intumescent flame retardancy with robust char formation and low smoke contribution in many thermoset and coating systems.

DESCRIPTION

Exolit AP 740 is a polymeric ammonium polyphosphate flame retardant that functions mainly in the condensed phase by generating phosphoric species that promote dehydration and char formation.
Exolit AP 740 supports intumescence by helping form an expanded protective foam char layer that insulates and shields the underlying polymer or coating.
Exolit AP 740 typically appears as a white, free-flowing powder, and Exolit AP 740 is used as an additive flame retardant that is physically incorporated into the formulation.

Exolit AP 740 performance depends on the full intumescent formulation design, including binder selection, carbon source selection, blowing agent selection, pigment volume concentration, and curing conditions.
Exolit AP 740 can be used alone in some systems, but Exolit AP 740 is often combined with synergists to optimize expansion ratio, char cohesion, and durability.
Exolit AP 740 is generally selected for applications that require halogen-free flame retardancy and reduced smoke, but mechanical property impact and moisture sensitivity should be evaluated during formulation development.

Exolit AP 740 should be stored dry and protected from humidity to maintain flow and to avoid caking.
Exolit AP 740 dust can irritate eyes and respiratory tract, so dust control and appropriate PPE are recommended during handling.
Exolit AP 740 should be used according to supplier specifications and applicable regulations relevant to the target application and market.

PROPERTIES

Chemical Type: Polymeric ammonium polyphosphate (phosphorus-nitrogen flame retardant)
Appearance: White free-flowing powder (grade dependent)
Odor: Practically odorless
Phosphorus Content: 18.0–20.0% (w/w) (typical)
Nitrogen Content: 21.0–23.0% (w/w) (typical)
Density: Approx. 1.8 g/cm³ (typical)
Bulk Density: Approx. 0.6 g/cm³ (typical)
Solubility: Very low solubility in water; insoluble in most organic solvents (typical for polymeric APP)
Mode of Action: Condensed-phase char promotion and intumescence (phosphorus/nitrogen synergism)
Smoke Behavior: Often supports reduced smoke compared with many halogenated systems (system dependent)
Thermal Behavior: Decomposes under heat to form protective phosphate species and release nonflammable gases (system dependent)
Storage Temperature: 5–30°C, dry, tightly closed
Shelf Life: Typically 24 months in original sealed packaging (supplier dependent)

FIRST AID

Inhalation:
Move to fresh air if dust is inhaled.
Seek medical attention if respiratory irritation persists.
Avoid breathing dust during handling and powder transfer.

Skin Contact:
Wash with soap and water after contact.
Remove contaminated clothing and wash before reuse.
Seek medical advice if irritation develops or persists.

Eye Contact:
Rinse cautiously with water for several minutes.
Remove contact lenses if present and easy to do, then continue rinsing.
Seek medical attention if irritation persists.

Ingestion:
Rinse mouth with water.
Seek medical attention if discomfort occurs or if a significant amount is swallowed.
Never give anything by mouth to an unconscious person.

Note to Physicians:
Treat symptomatically.
No specific antidote is required.
Provide supportive care based on exposure route and symptoms.

HANDLING AND STORAGE

Handling:
Use appropriate PPE including gloves and safety glasses, and use dust protection as needed.
Avoid generating dust and avoid inhalation of fine powder.
Wash hands after handling and before eating, drinking, or smoking.

Ventilation:
Use local exhaust or general ventilation where dust may be generated.
Maintain good airflow during weighing, charging, and mixing operations.
Minimize airborne particulate accumulation in enclosed areas.

Storage:
Store in tightly closed containers in a cool, dry place away from moisture.
Protect from humidity to prevent caking and maintain free-flowing behavior.
Keep containers properly labeled and protected from contamination.

Spill and Leak Procedures:
Avoid dust generation and sweep or vacuum using equipment designed for fine powders.
Collect spilled material into suitable containers for disposal according to local regulations.
Clean residues with wet wiping if needed to reduce airborne dust.

Handling Precautions:
Optimize dispersion and wetting in resin systems to prevent agglomerates and to maintain consistent fire performance.
Validate fire performance with appropriate testing because intumescence depends strongly on binder system and package balance.
Rotate stock using FIFO practices to maintain consistent quality and predictable processing behavior.