Other Phosphorus-Containing Pigments

Iron Phosphide. Commercial iron phosphide anticorrosive pigments usually consist of Fe2P [12751-22-3], Mr 142.7, with traces of FeP and Si02. The pigment is a powder with a metallic gray color and contains 70 % Fe, 24 % P, 2.5 % Si, and 3.0 % Mn. The density is 6.53 g/cm3 and the mean particle size is ca. 3 5 pm. 

Property Commercial product 1 (Sicor SPO, BASF) [5.67] Commercial product 2 (Sicor NOP, BASF) [5.67] Commercial product 3 (Heucophos ZPZ, Heubach) [5.68] 

Iron phosphide anticorrosive pigments are recommended by manufacturers as replacement materials for zinc dust to reduce the price of zinc-rich paints [5.103]. For toxicological data, see Section 5.2.14. 

A trade name for iron phosphide is Ferrophos (Hooker Chemicals Plastics Corp., USA). 

Zinc Hydroxyphosphite. Commercial zinc hydroxyphosphite [64539-51-1] is a white, nontoxic pigment with basic character. 

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Ammonium polyphosphates, on the other hand, are relatively water insoluble, nonmelting solids with very high phosphorus contents (up to about 30%). There are several crystalline forms and the commercial products differ in molecular weights, particle sizes, solubilities, and so on. They are also widely used as components of intumescent paints and mastics where they function as the acid catalyst (i.e., by producing phosphoric acid upon decomposition). They are used in paints with pentaerythritol (or with a derivative of pentaerythritol) as the carbonific component and melamine as the spumific compound.22 In addition, the intumescent formulations typically contain resinous binders, pigments, and other fillers. These systems are highly efficient in flame-retarding hydroxy-lated polymers. 

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