StructureAmmonium polyphosphate
Formula
(NH4PO3)n
CAS No. 68333-79-9
EINECS/ ELINCS No. 269-789-9
Synonyms Polyphosphoric acids, ammonium salts

Ammonium polyphosphate

Ammonium Polyphosphate is an environment-friendly, non-toxic, halogen-free flame retardant, chemically Ammonium Polyphosphate is an organic salt of polyphosphoric acid and ammonia.

The chain length (n) of this polymeric compound can be linear or branched. Depending on the polymerization degree there are two main types of  Ammonium Polyphosphates (APPs):

 

APP Phase I – these are short, linear chain APP’s where n<100 are highly water soluble and less thermally stable, decomposing at temperatures above 150°C

The APP behaves as a flame retardant in an intumescent coating with the presence of other chemicals. 

 

Characteristics & Uses (Phase I)

  • KYLIN APP1 has a high phosphorous and nitrogen content, a high polymerization degree, low water solubility, good thermal stability and low toxicity.

    Uses: It is used to prepare a number of high-efficiency expanding flameproof coatings used in the construction industry, ships, trains, cables etc. Also suitable for the flameproof treatment of wood, plywood, fiberboard, paper, fibers…
  • KYLIN APP100 has a lower phosphorous and higher nitrogen content than KYLIN APP1, high water solubility and good compatibility with other flame retardants and auxiliary chemicals.

    Uses: It is used to prepare 20% Phosphorous/Nitrogen containing flame retardants, it can be used solely or in conjunction with other materials in the flameproof treatment for textiles, papers, fibers and woods. Special treatment can be used to prepare 50% high concentration flameproof formulations required for special applications
  • KYLIN APP111 has a lower phosphorous and higher nitrogen content than KYLIN APP1, very high water solubility (over 150 grams in 100ml of water at 25°C) and good compatibility with other flame retardants.

    Uses: It can be used solely or in conjunction with other materials in the flameproof treatment for textiles, papers, fibers and woods.

 

APP Phase II – these APPs have a high polymerization degree, where n>1000 and is branched (cross-linked), it also has higher thermal stability, decomposition starts around 300°C

The APP behaves as a flame retardant in an intumescent coating with the presence of other chemicals. When APP-II is exposed to fire or heat, it decomposes to polymeric phosphate acid and ammonia. The polyphosphoric acid reacts with hydroxyl groups in the formulation to form a nonstable phosphate ester. Following dehydration of the phosphate ester, a carbon foam is built up on the surface and acts as an insulation layer. Due to this mechanism the APP does not generate additional quantities of smoke.



Characteristics & Uses (Phase II)

  • KYLIN APP201 & KYLIN APP203 (modified with Silane) can be used in solvent and water based intumescent coatings, various types of systems such as rubber, PU foam, expandable fireproof coating etc. The APP is compatible with a variety of different resin types:



    Thermosetting resins – Polyester, epoxy (EP), polyurethane (PUR),.. The APP can also be used with ATH (Alumina trihydrate) which is a flame retardant filler allowing significant reductions in ATH to improve processability.



    Thermoplastic resins – Polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC),… here the APP exhibits good processability, good retention of mechanical properties and good electrical properties.

 

  • KYLIN APP203 exhibits the following feature compared to the untreated grade (KYLIN APP201):

    Reduced solubility in water

    Reduced viscosity in water

    Improved dispersibility and compatibility with polymers and resins

    Better powder fluidity

    Improved thermal expansion efficiency​


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