Aluminum phosphite, CAS number 15099-32-8, chemical formula: Al2(HPO3)3·2H2O, is a phosphorus-based halogen-free environmentally friendly flame retardant. It can synergize with various phosphorus and nitrogen flame retardants and is used to retard PA and PBT materials. It also helps to slow down oxidation and discoloration during processing and fully complies with RoHS 2.0, REACH regulations, and other environmental regulations. It is a white to slightly yellow crystalline powder at room temperature; at high purity, it is pure white. Particle size and crystallinity affect its flowability. It is sparingly soluble in water and most organic solvents; soluble in strong acids and concentrated strong alkali solutions; it slowly hydrolyzes in humid environments; it has good thermal stability, with an industrial-grade thermal decomposition temperature of approximately 360℃. During heating, it first loses its water of crystallization, then decomposes to produce AlPO4, PH3, P4O6, etc.

I. Product Advantages

1. Halogen-free and environmentally friendly, with low smoke density;

2. Aluminum phosphite has good resistance to high-temperature oxidation, adaptable to a wide range of processing techniques and applications;

3. Low water solubility, good resistance to hydrolysis and precipitation.

II. Physical Properties

D50: 9~12μm

Phosphorus Content: 30~32%

Moisture Content≤0.5%

Whiteness≥97%

True Density g/cm3: 1.9±0.1

Bulk Density g/cm3: 0.4~0.6

pH Value: 4~6

Water Solubility g/100ml≤0.5

III. Application Areas

Can be used in combination with aluminum diethylphosphite, MPP, MCA, etc., suitable for thermoplastic resin materials such as PA and PBT.

IV. Processing Precautions

1. During processing, to achieve a suitable plasticizing effect, it is recommended to use a lower processing temperature to obtain better overall performance.

2. Fillers and colorants may adversely affect the flame retardant effect of aluminum phosphite, or even cause it to fail. Verification is required before using fillers and colorants.

V. Packaging/Storage

25kg/bag; Transport as general chemicals, store in a dry, cool place, avoid direct sunlight.

Phosphorus in aluminum phosphite can form phosphoric acid or polyphosphoric acid with strong dehydrating properties at high temperatures, catalyzing the rapid dehydration and carbonization of polymer substrate surfaces. This catalytic effect, synergistic with aluminum diethylphosphonate, generates a denser and more stable coke layer. Its protective effect is superior to that of a single flame retardant, more effectively blocking heat and oxygen, and preventing dripping. At high temperatures, aluminum phosphite releases phosphorus-containing free radicals (PO·). These free radicals, upon entering the gas phase, can capture high-energy free radicals (H· and OH·) in the combustion reaction, interrupting the chain reaction of combustion and achieving a "fire extinguishing" effect.