Coating, Flame Retardants

APP VP-201 / VP-201S Ammonium Polyphosphate Phase II Flame Retardant

APP VP-201 and VP-201S are halogen-free Ammonium Polyphosphate Phase II flame retardant additives engineered for intumescent and non-halogenated fire-retardant systems. They decompose under heat to form polyphosphoric acid and ammonia, producing a protective char layer that reduces ignition, smoke, and heat transfer. Both grades offer high thermal stability and very low solubility, supporting long-term performance in coatings, plastics, resins, wood protection, and fire-extinguishing compounds. VP-201S provides a finer particle size for improved dispersion and smoother coating finishes.

Attributes

Key Features and Benefits

Halogen-free formulation provides low toxicity and low smoke behaviour.
Thermal stability above 270 °C supports high-temperature resin and polymer processing.
Low water solubility allows stable performance in outdoor, marine, and moisture-sensitive applications.
Strong intumescent action forms a dense char layer for improved fire resistance.
Consistent particle size supports predictable dispersion and coating properties.
VP-201: 15–25 µm D50; VP-201S: <12 µm D50 for enhanced coating smoothness.
Broad polymer compatibility enables use across PP, PE, EVA, PU, epoxy, polyester, rubber, textiles, and composites.
Low viscosity in aqueous systems simplifies liquid intumescent coating formulation.

Specifications

Technical Highlights

Appearance: White powder.
CAS number: 68333-79-9.
Chemical formula: (NH₄PO₃)ₙ (n > 1000).
P₂O₅ content: VP-201 ≥71%, VP-201S ≥70%.
Total phosphorus: VP-201 ≥31%, VP-201S ≥30%.
Nitrogen content: VP-201 ≥14%, VP-201S ≥13.5%.
Decomposition temperature: >270 °C.
Solubility (10% aq, 25 °C): VP-201 <0.5%, VP-201S <0.7%.
pH (10% aq, 25 °C): 5.5–7.5.
Viscosity (10% aq, 25 °C): <20 mPa·s.
Moisture: <0.3%.
Particle size D50: VP-201 = 15–25 µm, VP-201S <12 µm.
Particle size D100: VP-201 <100 µm, VP-201S <40 µm.

Download Technical Data Sheet (TDS)

Practical industry uses

Applications

Intumescent coatings for steel structures, wood, buildings, marine vessels, and rail infrastructure.
Coatings for cables and wire harnesses.
Plastics and polymers including PP, PE, EVA, TPU, PU, epoxy resin, unsaturated polyester, and halogen-free cable compounds.
Injection-moulded and extruded flame-retardant plastics.
Wood protection and fire-retardant finishes.
Textile and fabric fire-retardant coatings.
Rubber fire-retardant formulations.
Fire-extinguishing powders for wildfire suppression, oil-field and industrial safety, mining emergencies.
Intumescent sealants and adhesives.
FR masterbatch systems and FRP composites requiring strong char development.