Ammonium Polyphosphate(App) Manufacturer

As an Ammonium polyphosphate (APP) manufacturer in China, Zhejiang Xusen Flame Retardants Incorporated Company produces APP as one of the core single-substance families in our halogen-free flame retardant range. The substance is CAS 68333-79-9, molecular formula (NH4PO3)n, supplied as a white, odourless, non-toxic powder that decomposes without releasing corrosive gases. Our high-polymerization grades are built at a degree of polymerization of n≥1000, which is the structural basis for the low water solubility and thermal stability that formulators depend on in thermoplastic and thermoset systems.

Two APP families are available: the high-polymerization XS-APPII series and a surface-modified APP series. Between them they serve polyolefins, engineering plastics, adhesives, composite materials, cable compounds, coatings and textile backcoatings, and they are designed to work alongside char formers, nitrogen synergists and other halogen-free components rather than as a stand-alone answer.

APP Product Range and Where Each Family Fits

The range is kept deliberately narrow and technically distinct. The choice between an uncoated high-polymerization grade and a surface-modified grade is normally decided by the matrix, the processing temperature and the dispersion demand of the line, not by price alone.

Both families sit inside the wider Single-substance flame retardants range, which also covers MCA, organophosphorus and ATH chemistry for systems that need more than one active component.

How APP Works in a Burning Polymer

APP acts mainly in the condensed phase. On heating it decomposes into polyphosphoric acid, which promotes dehydration and carbonization at the surface of the organic substrate. The intumescent char that forms expands, covers the substrate and isolates it from air, cutting off the fuel and oxygen exchange that keeps a flame going.

A secondary gas-phase contribution comes from the non-combustible CO2 and NH3 released during decomposition, which dilute the oxygen available at the flame front and help the burning material self-extinguish. Because the chemistry is phosphorus-nitrogen based and halogen-free, burning APP-containing compounds generate less smoke and no halogen acid gases.

Application Fit by Matrix and Process

Polyolefins, cable compounds and TPE

In PP, PE and TPE systems APP works as the acid source of an intumescent package, usually with a char former and a blowing agent. Cable compounds and low-smoke zero-halogen jackets frequently combine APP with mineral fillers, and the balance between the two determines smoke density, elongation and the fire performance achieved. For PP-based work we also supply a composite flame retardant for PP where a pre-formulated system is easier to dose than separate components.

Engineering plastics — PA, PBT and other modified plastics

In polyamides and polyesters, APP is normally used as part of a phosphorus-nitrogen system rather than on its own. Nitrogen-rich synergists such as Melamine cyanurate (MCA) shift the acid-to-blowing-agent ratio and allow the required rating to be reached at a lower total additive load, which protects tensile strength and impact performance in connectors, housings and structural parts.

Coatings, adhesives, textiles and thermosets

APP for paint and coating applications is used in intumescent coatings where the acid source must disperse cleanly in the binder and remain stable through drying or curing. The same chemistry serves adhesives, PU insulation, epoxy resins, rubber, carpets and fabric coatings, where the requirement is usually a combination of flame retardancy, low smoke and compatibility with the carrier.

Specification Variables That Drive APP Performance

APP is not a single commodity. Two grades carrying the same CAS number can behave very differently on the same extrusion line, so the following variables are the ones that decide whether a formulation meets its rating and holds its mechanical properties.

• Degree of polymerization — higher values reduce water solubility and migration, which matters for humid, outdoor or long-service-life parts.
• Phosphorus and nitrogen content — sets the acid-source efficiency delivered per unit mass of additive.
• Water solubility and pH of the aqueous suspension — governs resistance to leaching and to hydrolysis during processing.
• Particle size distribution (D50, D97) and sieve residue — controls dispersion quality, filter pressure and surface defects.
• Moisture content — affects feeding stability and the risk of hydrolysis in high-temperature zones.
• Thermal decomposition onset and residue — must sit above the processing window of the matrix.
• Surface treatment type — uncoated, or modified for compatibility and lower viscosity.
• Bulk density and flowability — determines feeder behaviour, dust generation and housekeeping load.

Compounding and Line Integration

We support the compounding step as well as the material. APP is typically fed into a twin-screw extruder, often through a side feeder downstream of the polymer melt to limit thermal exposure and moisture pickup. Temperature profile, screw configuration and vacuum level all influence how much of the acid source reaches the finished pellet intact.

Where a masterbatch route suits the converter better, APP can be let down into a carrier resin matched to the final matrix so that dosing accuracy and dispersion improve at the machine. The points we work through with customers include:

• Feed zone placement and whether the selected grade needs pre-drying.
• Shear and temperature limits relative to the decomposition onset of the grade.
• Compatibility with the carrier resin, impact modifier and any glass or mineral reinforcement.
• Dispersion quality, plate-out and die build-up across a full production run.
• Target let-down ratio and the resulting flame-retardant loading in the finished part.

Manufacturing Base, Capacity and Quality Control

APP is produced at our two manufacturing bases in Jiashan, Zhejiang and Juancheng, Shandong, with a current annual production capacity of 12,000 tons that continues to expand. Both sites run our own production workshops and warehouses, equipped with complete production and quality inspection equipment.

Every step of the product formation process follows the ISO 9001-2015 quality management system. Our APP synthesis technology is developed in-house and is characterised by high stability, high viscosity, good dispersion, low water solubility and strong resistance to precipitation and migration, with a concentrated high-polymer molecular weight distribution.

• Zhejiang provincial-level scientific research laboratory.
• Joint laboratory with the Shanghai Institute of Chemistry dedicated to advanced flame-retardant materials.
• China's advanced light industry flame retardant engineering technology research centre, established with Beijing Technology and Business University, Shandong Haihuai Institute and Shandong Brothers.
• Invention and utility model patents, plus participation in the formulation of national and industry standards.

Compliance Evidence and Documentation

Our products comply with the requirements of the WEEE, RoHS and EUP directives, and APP is registered under REACH. An APP RoHS test report forms part of the compliance file, and the same documentation set is maintained across the halogen-free range.

Information We Use to Configure Your Solution

A grade recommendation is only as good as the process data behind it. We prepare the selection and the quotation from the following inputs, and the more precisely they are defined, the closer the first sample comes to the target.

Packaging, Delivery and Ongoing Support

Packaging format, pallet configuration and container loading are agreed against the order quantity, the grade and the destination. Because APP is sensitive to moisture in storage, the packaging barrier and the storage guidance are settled with the order so the material arrives in the condition the line expects.

Technical support continues after delivery. We work with customers on dispersion problems, plate-out, rating shortfalls and reformulation when a matrix or a standard changes, and the same APP chemistry can be supplied through a masterbatch route where a converter prefers a ready-to-dose pellet.

Frequently Asked Questions

What is the difference between high-polymerization APP and modified APP?

High-polymerization APP such as the XS-APPII series is uncoated crystalline ammonium polyphosphate with a degree of polymerization of n≥1000 and a concentrated molecular weight distribution, which delivers low water solubility and high thermal stability. Modified APP carries a surface treatment that improves compatibility with the target material and lowers both water solubility and viscosity, which helps in matrices where dispersion and interfacial bonding are the limiting factors.

Can APP be used on its own in polypropylene?

APP is an acid source, so in PP and PE it is normally combined with a char former and a blowing agent to build a working intumescent system. The loading and the ratio between components are set by the target rating, the filler balance and the mechanical properties the part has to keep. Where separate dosing is inconvenient, we can supply a pre-formulated composite system instead.

Is APP suitable for polyamide and polyester compounds?

Yes, as part of a phosphorus-nitrogen system. In PA6, PA66 and PBT, APP is paired with a nitrogen synergist such as melamine cyanurate so that the required rating is reached at a lower total additive load. This matters in glass-filled connectors and housings, where excessive loading degrades tensile strength and impact resistance.

Which compliance documents accompany APP?

APP complies with the WEEE, RoHS and EUP directives and is registered under REACH. A technical data sheet, a safety data sheet, an APP RoHS test report and the REACH registration status are issued with the supply, and the documentation set is aligned with the compliance requirements of the destination market.

What information do you need to quote an APP grade?

We need the polymer or binder system, the target flame-retardant standard and rating, the processing method and temperature profile, the intended additive loading, the filler and reinforcement package, the physical properties that must be retained, the service exposure conditions, the compliance market and the annual volume with delivery destination. With those inputs we can select the grade and prepare a quotation that reflects the real working point.

How is APP supplied and delivered?

Packaging format, pallet configuration and container loading are confirmed against the order quantity, the grade and the destination, with the moisture barrier agreed at the same time. Delivery scope is stated in the offer so that the receiving site knows exactly what arrives and how the material should be stored before use.