Ammonium polyphosphate CAS 68333-79-9 APP

Product Overview

Ammonium polyphosphate (APP) is a phosphorus–nitrogen inorganic polymer — a white crystalline powder built from (NH₄PO₃)ₙ chains — and one of the most effective halogen-free flame retardants on the market. As the acid source of intumescent (expanding-char) flame-retardant systems, it protects steel structures, plastics, wood, textiles and coatings by building a heat-insulating carbon barrier on exposure to fire.

APP's appeal is its chemistry and its safety: phosphorus and nitrogen work synergistically to quench combustion, it is halogen-free (low smoke, low toxicity), nearly neutral, and thermally stable above 250 °C. From intumescent fire-protective coatings and polypropylene/polyethylene compounds to polyurethane, epoxy, rubber, fiberboard and dry-powder extinguishers, one polymer serves the entire fire-safety material chain.

A single polymer, four core value propositions:

Intumescent Flame Retardancy:

● the acid source of halogen-free intumescent (IFR) systems for polymers and coatings;

Fire-Protective Coatings:

● the active flame retardant of waterborne and solvent-borne intumescent coatings for steel and timber;

Polymer & Material Flame Retardancy:

● flame retardant for PP/PE, polyurethane, epoxy, rubber, wood, fiberboard and textiles;

Fire Extinguishing & Specialty:

● an effective dry-powder extinguishing agent and a slow-release nitrogen–phosphorus fertilizer.

Product Information (Quick Facts)

Chemistry & Types

APP is a linear ammonium salt of polyphosphoric acid. On heating, it first de-ammoniates and dehydrates to polyphosphoric acid — a powerful dehydrating agent — which then chars the carbon source and releases inert gases; the expanding char layer insulates the substrate and excludes oxygen. This is the classic three-part intumescent mechanism: APP is the acid source, a polyol (e.g. pentaerythritol) is the carbon source, and melamine provides the blowing gas.

Two commercial types dominate. Type Iis water-soluble and suited to clear intumescent coatings and water-based systems. Type II has very low water solubility , higher thermal stability and superior weather resistance — the standard for outdoor coatings, polymers and demanding applications.

Key Features & Benefits

● Halogen-free, low-smoke, low-toxicity: fire protection without halogen corrosivity or dense toxic smoke.

● Proven intumescent performance: builds dense, insulating char in IFR coatings and polymer systems.

● Water-resistant Type II: low solubility for outdoor coatings, polymers and humid service.

● Broad polymer compatibility: PP/PE, polyurethane, epoxy, rubber, wood, fiberboard and textiles.

● Nearly neutral and easy to compound: non-corrosive, dust-friendly additive for extrusion and coating lines.

● Multi-function value: flame retardant, extinguishing agent and slow-release fertilizer from one polymer.

Main Applications

Intumescent Flame Retardancy (Core Application)

APP is the backbone of modern intumescent fire protection:

● IFR formulations: combined with polyol (carbon source) and melamine (gas source) in intumescent systems;

● Thermoplastic polymers: flame-retardant loading in PP, PE and engineering compounds;

● Thermosets and elastomers: polyurethane, epoxy and rubber formulations;

● Char-forming performance: dense, insulating, cohesive char with low smoke in real-fire conditions.

Fire-Protective Coatings

● Steel structures: intumescent coatings expanding into thick insulating char under fire, protecting load-bearing steel;

● Timber and wood products: fire-retardant coating and impregnation for construction timber;

● Waterborne and solvent-borne systems: compatible with both coating technologies;

● Building and transport: passive fire protection for buildings, ships and vehicles.

Polymer & Material Flame Retardancy

● Plastics: flame-retardant additive for polypropylene, polyethylene and compounds;

● Wood, fiberboard and paper: fire-retardant treatment and impregnation;

● Textiles: flame-retardant coating and finishing (including melamine-treated Type II grades);

● Sealants and adhesives: fire-retardant additive in construction and industrial products.

Fire Extinguishing & Specialty Applications

● Dry-powder extinguishers: effective extinguishing agent for solid and liquid fires;

● Fertilizer: slow-release nitrogen–phosphorus nutrient for agriculture;

● Smoke suppression: char-promoting action reduces smoke generation in burning polymers;

● Specialty fire protection: fire-resistant composites, cables and insulation systems.

Packaging, Storage & Transport

Packaging (customizable):

● 25 kg multi-wall paper bag with PE liner, 25 kg fiber drum, or 500 kg – 1,000 kg FIBC;

Storage:

● Keep in a cool, dry, well-ventilated area away from direct sunlight and heat;

● Keep containers tightly closed to prevent moisture pick-up and caking (Type I is hygroscopic);

● Store away from strong oxidizers and incompatible materials;

● Recommended storage temperature 5 °C – 35 °C.

Why Choose Jinan Future Chemical Co., Ltd.?

● Factory-direct supply: own production capacity, transparent pricing, no middleman markup;

● Stable quality: strict internal control, every batch tested, COA with every shipment

● Flexible specifications: Type I / Type II, sample orders welcome;

● Export experience: familiar with sea/air shipping documentation for chemical commodities, complete paperwork support;

FAQ

Q1: What is ammonium polyphosphate (APP) used for?

APP is a halogen-free flame retardant and the acid source of intumescent (expanding-char) systems. It is used in fire-protective coatings for steel and timber, flame-retardant plastics (PP/PE, polyurethane, epoxy, rubber), wood, fiberboard and textiles, dry-powder fire extinguishers, and slow-release nitrogen–phosphorus fertilizers.

Q2: What is the difference between Type I and Type II APP?

Type I is a short-chain polymer that is water-soluble — suited to clear intumescent coatings and water-based systems. Type II is long-chain with very low water solubility and higher thermal stability, giving superior weather and humidity resistance — the standard for outdoor coatings, plastics and demanding applications. Choose Type I for soluble systems, Type II for durability.

Q3: How does APP work as a flame retardant?

On heating, APP de-ammoniates and dehydrates to polyphosphoric acid, a strong dehydrating agent that chars the carbon source (e.g. pentaerythritol), while ammonia and inert gases from the blowing agent (e.g. melamine) expand the char. The resulting intumescent carbon layer insulates the substrate from heat and excludes oxygen — the classic acid-source–carbon-source–gas-source mechanism.

Q4: Is APP safe to handle?

APP is halogen-free, nearly neutral, non-toxic and low-smoke — one of the safest flame retardants available — but the fine powder can irritate the eyes and respiratory tract, and dust can form explosive atmospheres in bulk handling. Use dust masks, gloves and goggles, avoid generating dust, and control ignition sources. It is an industrial chemical, not a food ingredient.